Method for preparing nano-carbon and secondary doped polyaniline composite solvent-free coating

Abstract

The present invention provides a method for preparing a nano-carbon and secondary doped polyaniline composite solvent-free coating, relating to the technical field of polyaniline composite materials. A method for secondary doping of polyaniline is adopted to prepare a composite material of graphene, carbon nanotubes and secondary doped polyaniline, thereby solving the problems of agglomeration and dispersion of polyaniline and having excellent corrosion inhibition performance. The product morphology is more uniform and the nanofibers are more unified. Specifically, the product morphology is improved by controlling the ratio of graphene to aniline and the ratio of carbon nanotubes to aniline. The carbon nanotubes wrapped by polyaniline are neatly arranged on the surface of the graphene with uniform size and a fiber length of more than 800 nm. The agglomeration problem of the graphene and carbon nanotubes themselves is avoided, and various properties of the product are effectively improved. The product is applied to a solvent-free epoxy coating to obtain a solvent-free epoxy coating with excellent comprehensive performance.

Description

Technical Field

[0001] The invention relates to the technical field of polyaniline composite materials, in particular to a method for preparing a nano-carbon and secondary doped polyaniline composite solvent-free coating. Background Art

[0002] Currently, most research on anti-corrosion coatings, both domestically and internationally, focuses on reducing VOC emissions through water-based coatings. However, the overall anti-corrosion performance of water-based coatings is inferior to that of oil-based coatings. Water has a high surface tension, and contaminants in the coating system can cause craters in the coating. Furthermore, the evaporation of water as a solvent increases the likelihood of coating defects.

[0003] Solvent-free epoxy coatings eliminate the need for organic volatile solvents as a dispersion medium during their manufacture and application. This reduces air pollution from organic volatile solvents and the likelihood of coating defects. Furthermore, their excellent wet adhesion ensures durability in harsh corrosive environments. Furthermore, a single coat of solvent-free epoxy coating can achieve a higher effective film thickness, significantly reducing the number of application coats and lowering construction costs. Therefore, solvent-free coatings offer significant advantages and broad application prospects in the corrosion protection field.

[0004] However, solvent-free epoxy coatings have high viscosity and difficult construction due to their lack of solvents. This study explored the performance comparison of coatings made by mixing different epoxy resins and curing agents. The approach involved selecting the epoxy resin and curing agent, and then selecting pigments and fillers to achieve a coating with not only good physical properties but also excellent corrosion resistance.

[0005] Polyaniline (PAI), a conductive polymer made from the monomer aniline, is easy to synthesize, chemically stable, and possesses diverse structures. It is widely used, particularly in metal corrosion protection. However, PAI's application also faces urgent challenges, such as poor dispersibility and film tightness, which severely impact its corrosion resistance.

[0006] Carbon nanotubes and graphene are currently hot topics in the research of nanocarbon materials. Carbon nanotubes have excellent electrical conductivity, mechanical strength and toughness; graphene has excellent mechanical, optical, thermal and barrier properties. Carbon nanotubes and graphene have been widely used in capacitor materials, energy storage, seawater desalination, solar cells, and also have broad application prospects in the field of corrosion protection. Studies have shown that adding carbon-based materials to polyaniline can improve its electrical conductivity, while also improving its electrochemical and mechanical properties. The field has always hoped to prepare new materials with excellent corrosion resistance by compounding carbon nanotubes or graphene with secondary doped polyaniline, but conventional compounding methods cannot avoid the self-agglomeration of carbon nanotubes and graphene. The effect of the resulting composite material is worse than that of the product prepared by polyaniline and carbon nanotubes or graphene separately, and it cannot achieve the purpose of enhancing its corrosion resistance. Summary of the Invention

[0007] The present invention provides a method for preparing a solvent-free coating composited with nano-carbon and secondary doped polyaniline. The method adopts a secondary doping method of polyaniline to prepare a graphene and carbon nanotube composite material based on the secondary doped polyaniline. The composite material is used in the solvent-free coating to achieve the effect of 1+1+1>3, thereby solving the agglomeration and dispersion problems of the polyaniline and avoiding the self-agglomeration problem of the carbon nanotubes and graphene, thereby obtaining a solvent-free epoxy coating with excellent comprehensive performance.

[0008] The present invention provides a method for preparing a nano-carbon and secondary doped polyaniline composite solvent-free coating, comprising:

[0009] Adding a reactive diluent in a mass percentage of 6% to 8% to the epoxy resin, and uniformly dispersing the mixture at a rotation speed of 1200 to 1600 r / min for 3 to 8 minutes to prepare an epoxy resin mixture;

[0010] According to the mass ratio of filler to anti-rust filler of 1:1, the mass ratio of ceramic powder to barium sulfate of 2:1, and the mass ratio of micaceous iron oxide to calcium exchanged SiO2 of 3:1, ceramic powder, barium sulfate, micaceous iron oxide and calcium exchanged SiO2 are added to the epoxy resin mixture in sequence, and after adding the dispersant, the speed is adjusted to 2000-2600r / min and stirring is continued for 3-8 minutes;

[0011] The composite material of graphene, carbon nanotubes and secondary doped polyaniline is added to a mixture at a ratio of 0.1% to 3%, and finally 1% to 2% of an additive is added. The mixture is stirred for 1 hour to be uniformly dispersed, and then ground three times with a three-roll grinder to obtain a fineness of less than 40 μm. After cooling, a nano-carbon and secondary doped polyaniline composite solvent-free coating is prepared. The composite material of graphene, carbon nanotubes and secondary doped polyaniline is prepared by secondary doping and compounding aniline, graphene and carbon nanotubes at a mass ratio of 15 to 25:1:15 to 25 through polyaniline.

[0012] Optionally, the composite material of graphene, carbon nanotubes and secondary doped polyaniline is prepared by the following method:

[0013] (1) Taking two equal volumes of 1 mol / L doping acid solutions, respectively adding aniline-graphene mixture and ammonium persulfate, wherein the molar ratio of the aniline-graphene mixture to the ammonium persulfate is 0.8:1, and uniformly mixing the two with a magnetic stirrer for 1 to 2 hours, placing them at room temperature and allowing them to stand for 20 to 26 hours, and washing the obtained product with ethanol and deionized water to neutrality, and drying and grinding to obtain a primary doped polyaniline-graphene composite material; wherein the mass ratio of aniline to graphene in the aniline-graphene mixture is 15 to 25:1;

[0014] (2) adding excess ammonia water to the primary doped polyaniline-graphene composite material for dedoping, stirring with a magnetic stirrer for 1 to 2 hours, standing at room temperature for 20 to 26 hours, washing the obtained product with ethanol and deionized water until neutral, and finally drying and grinding to obtain an intrinsic polyaniline-graphene composite material;

[0015] (3) taking two equal volumes of 1 mol / L doped acid solutions, adding aniline-carbon nanotube mixture and ammonium persulfate respectively, wherein the molar ratio of aniline-carbon nanotube mixture to ammonium persulfate is 0.8:1, and uniformly mixing the two with a magnetic stirrer for 1 to 2 hours, placing them at room temperature and allowing them to stand for 20 to 26 hours, washing the obtained product with ethanol and deionized water until neutral, drying and grinding to obtain a primary doped polyaniline-carbon nanotube composite material; wherein the mass ratio of aniline to carbon nanotubes in the aniline-carbon nanotube mixture is 15 to 25:1;

[0016] (4) adding excess ammonia water to the primary doped polyaniline-carbon nanotube composite material for dedoping, stirring with a magnetic stirrer for 1 to 2 hours, standing at room temperature for 20 to 26 hours, washing the obtained product with ethanol and deionized water until neutral, and finally drying and grinding to obtain an intrinsic polyaniline-carbon nanotube composite material;

[0017] (5) The intrinsic polyaniline-graphene composite material and the intrinsic polyaniline-carbon nanotube composite material were added to a 1 mol / L doped acid solution in a mass ratio of 1:1, mixed and stirred, and allowed to stand for 20 to 26 hours. They were then filtered and washed with ethanol and deionized water in turn until neutral, and finally dried and ground to obtain a composite material of graphene, carbon nanotubes and secondary doped polyaniline.

[0018] Optionally, the mass ratio of aniline to graphene in the aniline-graphene mixture is equal to the mass ratio of aniline to carbon nanotubes in the aniline-carbon nanotube mixture, wherein the mass ratio of aniline to graphene in the aniline-graphene mixture is 18 to 22:1, and the mass ratio of aniline to carbon nanotubes in the aniline-carbon nanotube mixture is 18 to 22:1.

[0019] Optionally, the mass ratio of aniline to graphene in the aniline-graphene mixture is 20:1, and the mass ratio of aniline to carbon nanotubes in the aniline-carbon nanotube mixture is 20:1.

[0020] Optionally, the composite material of graphene, carbon nanotubes and secondary doped polyaniline is added to the mixture at a ratio of 0.1% to 3% by weight:

[0021] The composite material of graphene, carbon nanotube and secondary doped polyaniline is added into the mixture in a ratio of 1% to 3%.

[0022] Optionally, the composite material of graphene, carbon nanotubes and secondary doped polyaniline is added to the mixture at a ratio of 0.1% to 3% by weight:

[0023] The composite material of graphene, carbon nanotube and secondary doped polyaniline is added into the mixed material in a ratio of 1% to 2%.

[0024] Optionally, the composite material of graphene, carbon nanotubes and secondary doped polyaniline is added to the mixture at a ratio of 0.1% to 3% by weight:

[0025] The composite material of graphene, carbon nanotube and secondary doped polyaniline is added into the mixture in a ratio of 0.5% to 1%.

[0026] Optionally, the corrosion inhibition efficiency of the prepared composite material of graphene, carbon nanotubes and secondary doped polyaniline is greater than 80%, and the impedance value of the prepared composite material of graphene, carbon nanotubes and secondary doped polyaniline is greater than 1800Ω*cm2.

[0027] Optionally, the fiber length of the prepared composite material of graphene, carbon nanotubes and secondary doped polyaniline is greater than 800 nm.

[0028] Optionally, the fiber length of the prepared composite material of graphene, carbon nanotubes and secondary doped polyaniline is greater than 850 nm.

[0029] The present invention has the following beneficial technical effects:

[0030] The present invention provides a method for preparing a nano-carbon and secondary doped polyaniline composite solvent-free coating, wherein an intrinsic polyaniline-graphene composite material and an intrinsic polyaniline-carbon nanotube composite material are respectively added to a 1 mol / L doping acid solution in a mass ratio of 1:1, and a polyaniline secondary doping method is adopted to prepare a composite material of graphene, carbon nanotubes and secondary doped polyaniline, thereby solving the agglomeration and dispersion problems of polyaniline and having excellent corrosion inhibition performance; the composite material product of the graphene, carbon nanotubes and secondary doped polyaniline after secondary mixing and doping has more uniform morphology and more uniform nanofibers. Among them, by controlling the ratio of graphene to aniline and the ratio of carbon nanotubes to aniline, the product morphology is improved, and the carbon nanotubes wrapped with polyaniline are neatly arranged on the graphene surface with uniform size and a fiber length of more than 800nm; a composite material of graphene, carbon nanotubes and secondary doped polyaniline is prepared by a secondary doping method of polyaniline, which avoids the agglomeration problem of the graphene and carbon nanotubes themselves and effectively improves the various performances of the product. The performance is better than that of the product obtained by single doping or secondary doping of graphene or carbon nanotubes alone. When applied to solvent-free epoxy coatings, a solvent-free epoxy coating with excellent comprehensive performance is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 Impedance spectra of coatings prepared at different mass ratios of composite materials of graphene, carbon nanotubes and secondary doped polyaniline according to an embodiment of the present invention after immersion for 24 hours;

[0033] Figure 2 Impedance spectra of coatings prepared from composite materials of graphene, carbon nanotubes and secondary doped polyaniline at different mass ratios according to an embodiment of the present invention after immersion for 168 hours;

[0034] Figure 3 Impedance spectra of coatings prepared at different mass ratios of composite materials of graphene, carbon nanotubes and secondary doped polyaniline according to an embodiment of the present invention, which were immersed for 360 hours;

[0035] Figure 4 Impedance spectra of coatings prepared at different mass ratios of composite materials of graphene, carbon nanotubes and secondary doped polyaniline according to an embodiment of the present invention, which were immersed for 720 hours;

[0036] Figure 5Impedance spectra of coatings prepared at different mass ratios of composite materials of graphene, carbon nanotubes and secondary doped polyaniline according to an embodiment of the present invention after immersion for 1800 hours;

[0037] Figure 6 This is an equivalent circuit diagram of the impedance spectrum of the coating prepared in an embodiment of the present invention;

[0038] Figure 7 Schematic diagram of the change in resistance of a coating layer prepared at different mass ratios of a composite material of graphene, carbon nanotubes, and secondary doped polyaniline according to an embodiment of the present invention over time;

[0039] Figure 8 Schematic diagram of 72-hour salt spray test results of coatings prepared at different mass ratios of composite materials of graphene, carbon nanotubes and secondary doped polyaniline according to an embodiment of the present invention;

[0040] Figure 9 Schematic diagram of 360-hour salt spray test results of coatings prepared at different mass ratios of composite materials of graphene, carbon nanotubes and secondary doped polyaniline according to an embodiment of the present invention;

[0041] Figure 10 Schematic diagram of 1000-hour salt spray test results of coatings prepared at different mass ratios of composite materials of graphene, carbon nanotubes and secondary doped polyaniline according to an embodiment of the present invention;

[0042] Figure 11 Schematic diagram of metallographic images of coatings prepared at different mass ratios of the composite materials of graphene, carbon nanotubes and secondary doped polyaniline according to an embodiment of the present invention;

[0043] Figure 12 Impedance spectra of coatings prepared from composite materials of graphene, carbon nanotubes and secondary doped polyaniline according to an embodiment of the present invention and pigments with different mass ratios, which were immersed for 24 hours;

[0044] Figure 13 Impedance spectra of coatings prepared from composite materials of graphene, carbon nanotubes and secondary doped polyaniline according to an embodiment of the present invention and pigments with different mass ratios after immersion for 168 hours;

[0045] Figure 14 Impedance spectra of coatings prepared from composite materials of graphene, carbon nanotubes and secondary doped polyaniline according to an embodiment of the present invention and pigments with different mass ratios immersed for 360 hours;

[0046] Figure 15 Impedance spectra of coatings prepared from composite materials of graphene, carbon nanotubes and secondary doped polyaniline according to an embodiment of the present invention and pigments with different mass ratios, immersed for 720 hours;

[0047] Figure 16 Impedance spectra of coatings prepared from a composite material of graphene, carbon nanotubes, and secondary doped polyaniline according to an embodiment of the present invention and pigments with different mass ratios after immersion for 1800 hours;

[0048] Figure 17 Schematic diagram of the change in resistance over time of a coating prepared from a composite material of graphene, carbon nanotubes, and secondary doped polyaniline according to an embodiment of the present invention and pigments with different mass ratios;

[0049] Figure 18 Schematic diagram of the results of a 72-hour salt spray test on a coating prepared from a composite material of graphene, carbon nanotubes, and secondary doped polyaniline according to an embodiment of the present invention and pigments with different mass ratios;

[0050] Figure 19 Schematic diagram of the results of a 360-hour salt spray test on a coating prepared from a composite material of graphene, carbon nanotubes, and secondary doped polyaniline according to an embodiment of the present invention and pigments with different mass ratios;

[0051] Figure 20 Schematic diagram of the results of a 720-hour salt spray test on a coating prepared from a composite material of graphene, carbon nanotubes, and secondary doped polyaniline according to an embodiment of the present invention and pigments with different mass ratios;

[0052] Figure 21 Schematic diagram of metallographic images of coatings prepared from a composite material of graphene, carbon nanotubes, and secondary doped polyaniline according to an embodiment of the present invention and pigments with different mass ratios. DETAILED DESCRIPTION

[0053] 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.

[0054] The present invention provides a method for preparing a nano-carbon and secondary doped polyaniline composite solvent-free coating, comprising:

[0055] The active diluent is added into the epoxy resin at a mass percentage of 6% to 8%, and uniformly dispersed for 3 to 8 minutes at a rotation speed of 1200 to 1600 r / min to prepare an epoxy resin mixture; wherein styrenated phenol can be used as the active diluent.

[0056] Ceramic powder, barium sulfate, micaceous iron oxide and calcium-exchanged SiO2 are added to the epoxy resin mixture in the ratio of 1:1 in mass of filling filler to anti-rust filler, 2:1 in mass of ceramic powder to barium sulfate, and 3:1 in mass of micaceous iron oxide to calcium-exchanged SiO2. After adding the dispersant, the speed is adjusted to 2000-2600 r / min and stirring is continued for 3-8 minutes. The dispersant can be BYK-9076.

[0057] A composite material of graphene, carbon nanotubes, and secondary doped polyaniline is added to a mixture at a ratio of 0.1% to 3%, and finally 1% to 2% of an additive is added. The mixture is stirred for 1 hour to uniformly disperse, and then ground three times with a three-roll mill to a fineness of less than 40 μm. After cooling, a solvent-free composite coating of nanocarbon and secondary doped polyaniline is prepared. The composite material of graphene, carbon nanotubes, and secondary doped polyaniline is prepared by secondary doping polyaniline with aniline, graphene, and carbon nanotubes in a mass ratio of 15 to 25:1:15 to 25. BYK-SILCLEAN 3701 can be used as a leveling agent, 8240 CI is used as a phenolic epoxy resin, and LITE 2009 is used as a phenalkamine curing agent.

[0058] The composite material of graphene, carbon nanotubes and secondary doped polyaniline used in the embodiment of the present invention is prepared by the following method:

[0059] (1) Taking two equal volumes of 1 mol / L doping acid solutions, respectively adding aniline-graphene mixture and ammonium persulfate, wherein the molar ratio of the aniline-graphene mixture to the ammonium persulfate is 0.8:1, and uniformly mixing the two with a magnetic stirrer for 1 to 2 hours, placing them at room temperature and allowing them to stand for 20 to 26 hours, and washing the obtained product with ethanol and deionized water to neutrality, and drying and grinding to obtain a primary doped polyaniline-graphene composite material; wherein the mass ratio of aniline to graphene in the aniline-graphene mixture is 15 to 25:1;

[0060] (2) adding excess ammonia water to the primary doped polyaniline-graphene composite material for dedoping, stirring with a magnetic stirrer for 1 to 2 hours, standing at room temperature for 20 to 26 hours, washing the obtained product with ethanol and deionized water until neutral, and finally drying and grinding to obtain an intrinsic polyaniline-graphene composite material;

[0061] (3) taking two equal volumes of 1 mol / L doped acid solutions, adding aniline-carbon nanotube mixture and ammonium persulfate respectively, wherein the molar ratio of aniline-carbon nanotube mixture to ammonium persulfate is 0.8:1, and uniformly mixing the two with a magnetic stirrer for 1 to 2 hours, placing them at room temperature and allowing them to stand for 20 to 26 hours, washing the obtained product with ethanol and deionized water until neutral, drying and grinding to obtain a primary doped polyaniline-carbon nanotube composite material; wherein the mass ratio of aniline to carbon nanotubes in the aniline-carbon nanotube mixture is 15 to 25:1;

[0062] (4) adding excess ammonia water to the primary doped polyaniline-carbon nanotube composite material for dedoping, stirring with a magnetic stirrer for 1 to 2 hours, standing at room temperature for 20 to 26 hours, washing the obtained product with ethanol and deionized water until neutral, and finally drying and grinding to obtain an intrinsic polyaniline-carbon nanotube composite material;

[0063] (5) The intrinsic polyaniline-graphene composite material and the intrinsic polyaniline-carbon nanotube composite material were added to a 1 mol / L doped acid solution in a mass ratio of 1:1, mixed and stirred, and allowed to stand for 20 to 26 hours. They were then filtered and washed with ethanol and deionized water in turn until neutral, and finally dried and ground to obtain a composite material of graphene, carbon nanotubes and secondary doped polyaniline.

[0064] Furthermore, the mass ratio of aniline to graphene in the aniline-graphene mixture is equal to the mass ratio of aniline to carbon nanotubes in the aniline-carbon nanotube mixture. Preferably, the mass ratio of aniline to graphene in the aniline-graphene mixture is 18 to 22:1, and the mass ratio of aniline to carbon nanotubes in the aniline-carbon nanotube mixture is 18 to 22:1. By controlling the ratio of graphene to aniline and the ratio of carbon nanotubes to aniline within this range, the product morphology is improved, with polyaniline-coated carbon nanotubes neatly arranged on the graphene surface, achieving uniform size and fiber length exceeding 800 nm.

[0065] Optionally, the mass ratio of aniline to graphene in the aniline-graphene mixture is 20:1, and the mass ratio of aniline to carbon nanotubes in the aniline-carbon nanotube mixture is 20:1.

[0066] Optionally, the doping acid solution is one of an inorganic acid solution, an organic acid solution and a composite acid, and the molar concentration ratio of the inorganic acid to the organic acid in the composite acid is 1:1 to 1:6.

[0067] The doping acid solution used in the embodiments of the present invention is one of an inorganic acid solution, an organic acid solution, and a composite acid. The molar concentration ratio of the inorganic acid to the organic acid in the composite acid is between 1:1 and 1:6. Organic acids include, but are not limited to, formic acid, acetic acid, propionic acid, butyric acid, octanoic acid, adipic acid, oxalic acid, malonic acid, succinic acid, tartaric acid, benzoic acid, phenylacetic acid, perchloric acid, sulfuric acid, phosphoric acid, hydrochloric acid, and molybdic acid, or a mixture thereof. Preferably, the embodiments of the present invention use a tartaric acid solution. Furthermore, the preparation method of the embodiments of the present invention may also use a composite acid formed by combining an organic acid and an inorganic acid. The composite acid used in the embodiments of the present invention is primarily a mixture of an inorganic acid and an organic acid. The inorganic acids primarily include perchloric acid, sulfuric acid, phosphoric acid, hydrochloric acid, nitric acid, and molybdic acid. The organic acids primarily include acetic acid, oxalic acid, citric acid, tartaric acid, tannic acid, p-toluenesulfonic acid, phytic acid, and tannic acid. The composite acid has a molar concentration ratio of the inorganic acid to the organic acid between 1:1 and 1:6.

[0068] The composite material of graphene, carbon nanotubes, and secondary doped polyaniline prepared using the preparation method of the embodiment of the present invention has a corrosion inhibition efficiency greater than 78%, an impedance value greater than 1500Ω*cm2, and a fiber length greater than 800nm. The composite material of graphene, carbon nanotubes, and secondary doped polyaniline prepared using the optimal ratio can have a corrosion inhibition efficiency greater than 80%, an impedance value greater than 1800Ω*cm2, and a fiber length greater than 850nm.

[0069] In the graphene, carbon nanotubes and secondary doped polyaniline composite material used in the embodiment of the present invention, CNTs1:15RGO1:5 represents that the mass ratio of aniline to carbon nanotubes in the aniline-carbon nanotube mixture is 20:1, and the mass ratio of aniline CNTs to graphene RGO in the aniline-graphene mixture is 20:1.

[0070] Table 1 Polarization curve fitting results

[0071]

[0072] Table 1 is the fitting results of its polarization curve. When the mass ratio of carbon nanotubes (CNTs) to aniline (ANI) is controlled at 1:15 and the ratio of graphene (RGO) to aniline (ANI) is changed, the corrosion current will gradually decrease as the amount of RGO decreases. When the ratio of RGO to ANI is 1:20, the corrosion current reaches the minimum. At this time, the corrosion resistance of the product reaches the best, and the corrosion inhibition efficiency reaches 78.68%. When the amount of RGO is further reduced, the corrosion current begins to increase gradually. This is because the morphology of the product changes after adding different amounts of RGO. When the ratio of RGO to ANI is 1:25, the RGO content is low and cannot play a good template role. The agglomeration phenomenon of polyaniline is not changed, and the corrosion current is relatively high. When the amount of RGO is gradually increased, RGO begins to play a barrier role and provides a good template for polyaniline, allowing the CNTs-wrapped PANI to grow evenly on RGO. The specific surface area is maximized, the electrode interaction is sufficient, and the passivation effect of PANI is greatly exerted.

[0073] (1) The composite materials of graphene, carbon nanotubes and secondary doped polyaniline prepared by the secondary doping method have more uniform morphology and more uniform nanofibers. The product morphology is best when the ratio of RGO to ANI is 1:20 and the ratio of CNTs to ANT is 1:20. PANI wraps CNTs and arranges them neatly on the graphene surface with uniform size. The fiber length reaches 850nm.

[0074] (2) Through the analysis of Tafel curve and electrochemical impedance diagram, it can be concluded that polyaniline with different ratios has a certain anti-corrosion effect on metals. When the ratio of RGO to ANI is 1:20 and the ratio of CNTs to ANI is 1:20, the anti-corrosion effect of the composite material of graphene, carbon nanotubes and secondary doped polyaniline prepared by the polyaniline secondary doping method is significantly better than that of products with other ratios. The corrosion current is the lowest, the corrosion inhibition efficiency reaches 81.79%, and the impedance value is 1893.6Ω.

[0075] (3) The use of polyaniline secondary doping to prepare composite materials of graphene, carbon nanotubes, and secondary doped polyaniline can avoid the agglomeration of nanomaterials and effectively improve the various properties of the product, which is better than either single doping or secondary doping of the same composite material alone. This is a breakthrough in preparing composite materials of graphene / carbon nanotubes simultaneously with polyaniline, and the product performance is significantly lower than the composite products of graphene alone or carbon nanotubes alone with polyaniline.

[0076] Preferably, in the coating prepared in the embodiment of the present invention, the composite material of graphene, carbon nanotubes and secondary doped polyaniline is added to the mixture at a ratio of 1% to 3%. This not only improves the anti-corrosion performance of the coating through the anti-pitting and passivation effects of the polyaniline composite material, but also takes into account that the density of the coating will not be destroyed.

[0077] Preferably, in the coating prepared in the embodiment of the present invention, the composite material of graphene, carbon nanotubes and secondary doped polyaniline is added to the mixture at a ratio of 1% to 2%. At this ratio, the anti-corrosion performance of the coating is enhanced, and perhaps because the coating effect is better, it takes a longer time to observe the difference in the salt spray test.

[0078] Preferably, in the coating prepared in the embodiment of the present invention, the composite material of graphene, carbon nanotubes and secondary doped polyaniline is added to the mixture at a ratio of 0.5% to 1%, and the coating prepared therefrom has the most excellent pitting corrosion resistance.

[0079] In the coating prepared in the embodiment of the present invention, the mass ratio of the film-forming substance to the pigment is 6:4, the mass ratio of the filling filler to the rust-proof filler is 1:1, the mass ratio of the ceramic powder to the barium sulfate is 2:1, the mass ratio of the mica iron oxide to the calcium-exchanged SiO2 is 3:1, the mass percentage of the composite material of graphene and carbon nanotubes and secondary doped polyaniline is 1%, the mass percentage of the active diluent is 6% to 8%, and the mass backup ratio of the additive is 1% to 2%.

[0080] In order to ensure that the coating prepared by the coating of the embodiment of the present invention is fully adhered to the surface substrate, it is necessary to degrease and dust the Q235 iron plate (150mm×75mm) and polish it with 400-mesh sandpaper before applying the coating. The surface is cleaned with ethanol and then dried for use. The coating prepared by the embodiment of the present invention and the curing agent are mixed in a mass ratio of 1:2.5 to 3.5, and applied to the treated substrate surface by brushing, roller coating, etc. The coating thickness is 630±30μm. Dry it at room temperature for 7 days. After it is completely cured, basic physical tests, AC impedance tests, and neutral salt spray tests can be carried out.

[0081] Table 2 Basic physical properties of coatings of composite materials of graphene, carbon nanotubes and secondary doped polyaniline with different addition amounts

[0082]

[0083] Table 2 shows the basic physical properties of coatings prepared by adding different ratios of composites of graphene, carbon nanotubes, and secondary-doped polyaniline to solvent-free epoxy coatings. Compared to coatings containing pigments and fillers, these basic physical properties did not significantly change. As the volume concentration of pigments and fillers increased with the addition of different ratios of the composites, the viscosity of the coating gradually increased. When 3% of the composite of graphene, carbon nanotubes, and secondary-doped polyaniline was added, the viscosity of the coating reached 9985 mPa·s, making application more difficult. Comparing the wear resistance, impact resistance, and hardness tests with those without addition, it was found that the physical strength of the composite material containing graphene, carbon nanotubes, and secondary doped polyaniline decreased slightly with increasing addition levels. This is because the introduction of the prepared polyaniline composite material changes the integrity and density of the coating surface. Polyaniline, graphene, and carbon nanotubes are all nanoscale composite materials with very large specific surface areas. The filler oil absorption value also increases, which acts as a thickener and improves thixotropic properties. Adding just 3% can significantly affect the viscosity of the coating system. Furthermore, the direct addition and blending of the nanoscale graphene, carbon nanotubes, and secondary doped polyaniline composite material results in some uneven dispersion and agglomeration, resulting in a fineness of approximately 40 microns after grinding. In summary, with increasing addition levels of the composite material containing graphene, carbon nanotubes, and secondary doped polyaniline, the basic physical properties of the coating decrease slightly, but still maintain high values.

[0084] Table 3 Impedance fitting results of coatings with different addition amounts of graphene, carbon nanotubes and secondary doped polyaniline composites

[0085]

[0086] Figures 1 to 5 The Nyquist and Bode plots of the coatings prepared by adding different masses of composite materials of graphene, carbon nanotubes and secondary doped polyaniline to the solvent-free epoxy coating were drawn after being immersed in 3.5% NaCl solution for 24h, 168h, 360h, 720h and 1800h. As can be seen from the figure, after adding the composite materials of graphene, carbon nanotubes and secondary doped polyaniline, all the impedance arc radii have increased, proving that the addition amount of the composite materials of graphene, carbon nanotubes and secondary doped polyaniline has a relatively large impact on the corrosion resistance of the coating. Figure 1 -a, it can be seen that at the initial stage of immersion, the impedance values ​​of all coatings are higher than 1011Ω·cm2, and the barrier ability of the coatings is relatively strong. Figure 1-A shows that although composite materials of graphene, carbon nanotubes, and secondary doped polyaniline are widely used in the field of corrosion protection, and their excellent pitting resistance can be well utilized in coating protection, the more graphene, carbon nanotubes, and secondary doped polyaniline composite materials added, the better they are. The best addition amounts are 0.5% and 1%, while the smallest impedance arc is achieved at 3%. This is because a small amount of the composite material of graphene, carbon nanotubes, and secondary doped polyaniline can be relatively evenly dispersed within the coating, reacting with the metal to produce a dense passivation film, thereby exerting its pitting resistance. However, excessive addition may lead to uneven distribution within the coating. The composite material of graphene, carbon nanotubes, and secondary doped polyaniline will re-agglomerate within the coating, destroying the original dense network of the coating. Corrosive media can penetrate into the coating through these defective areas, thereby changing the overall corrosion resistance of the coating. This also explains that when the addition amount of the composite material of graphene, carbon nanotubes and secondary doped polyaniline exceeds 1%, the impedance value of the coating is smaller than that without adding polyaniline.

[0087] from Figure 5 -E shows that after 1800 hours of immersion, the impedance arc still has only one time constant, and the corrosive medium has not completely penetrated into the coating. Therefore, the impedance spectrum equivalent circuit diagram is as follows Figure 6 As shown in the figure, Rs represents the internal resistance of the solution, Qc represents the coating capacitance, and Rp represents the coating resistance. Furthermore, a comparison shows that when the addition amount of the composite material of graphene, carbon nanotubes, and secondary doped polyaniline is 1%, the coating has the largest impedance arc and the highest Bode plot, indicating the best shielding effect and more significant protection for the metal substrate.

[0088] Table 3 shows the results of impedance fitting. After comparison, it can be found that after 1800 hours of immersion, the impedance value of the sample with an addition of 1% can be maintained at 5.557×1010Ω·cm 2 , which is higher than the coating sample without adding graphene and carbon nanotubes and secondary doped polyaniline composite material 3.47×1010Ω·cm 2 , proving that the appropriate addition of graphene and carbon nanotubes to composite materials of secondary doped polyaniline can improve the anti-corrosion performance of the coating and provide better protection for metals.

[0089] like Figure 7 As shown in the figure, the coating prepared by adding a solvent-free coating of a composite material of graphene, carbon nanotubes and secondary doped polyaniline was immersed in a 3.5% NaCl solution for 1800 hours, and an AC impedance test was performed. The corresponding equivalent circuit model was used to fit the EIS. The immersion time was used as the horizontal axis, and the resistance value of the fitted coating was used as the vertical axis. The resistance change of the coating prepared by different compound pigments and fillers over time was plotted, as shown in the figure. Figure 7 shown.

[0090] from Figure 7 It can be seen that as the immersion time increases, the impedance values ​​of all coatings gradually decrease. At the beginning of the immersion, the impedance values ​​of all coatings are higher than 1011Ω·cm 2 After a long period of immersion, the impedance value gradually slowed down after 800 hours. After immersion for 1800 hours, the impedance value of all coatings can still be maintained at 1010Ω·cm 2 The above results in a good anti-corrosion effect. Furthermore, compared to a composite material without graphene, carbon nanotubes, and secondary doped polyaniline, it was found that when the amount of the composite material containing graphene, carbon nanotubes, and secondary doped polyaniline was less than 2%, the composite material had a positive effect on the anti-corrosion effect of the coating. Appropriate addition of the composite material of graphene, carbon nanotubes, and secondary doped polyaniline can effectively prevent agglomeration in the coating, without destroying the original dense structure of the coating surface. Furthermore, a dense passivation layer is formed on the metal surface. The presence of graphene can extend the diffusion path of water molecules and corrosive media to the metal surface, thereby increasing the shielding effect of the coating. When the amount of the graphene, carbon nanotube, and secondary-doped polyaniline composite material added exceeds 2%, it can be clearly seen that its impedance value is consistently lower than that of the composite material without graphene, carbon nanotube, and secondary-doped polyaniline. This is because the excessive addition of the graphene, carbon nanotube, and secondary-doped polyaniline composite material prevents it from being evenly dispersed in the coating, resulting in some agglomeration. Furthermore, the addition of too much graphene, carbon nanotube, and secondary-doped polyaniline composite material destroys the coating's compactness, making it easier for water molecules and corrosive media to penetrate the coating. Although the excessive graphene, carbon nanotube, and secondary-doped polyaniline composite material can form a passivation layer on the metal surface, providing a certain shielding effect for the metal, it is only the coating's last line of defense and does not work well with the coating on the metal substrate.

[0091] like Figures 8 to 10The following are photos of coatings prepared with different addition amounts of the composite material of graphene, carbon nanotubes and secondary doped polyaniline after 72h, 360h and 1000h of salt spray test. It can be found that at 72h, the sample with a 3% addition amount of the composite material of graphene, carbon nanotubes and secondary doped polyaniline showed blistering. This is because the excessive addition amount of the composite material of graphene, carbon nanotubes and secondary doped polyaniline resulted in uneven dispersion and agglomeration inside the coating, thereby destroying the density of the coating and making it easier for the corrosive medium to penetrate into the coating and produce blistering. 2% of the samples showed slight corrosion changes at the scratches. After 360h, it was found that all coatings had only a small amount of rust at the scratches, and no other phenomena occurred. Because the coatings did not differ much after one month of salt spray test and were all relatively corrosion resistant, the salt spray time was extended to 1000h. Figure 9 As can be seen in the figure, after 1000 hours of testing, the coating still showed relatively little corrosion in the scratched area, and the scratched area still showed no change in the exposed metallic luster. This is because the composite material of graphene, carbon nanotubes and secondary doped polyaniline and the passivation layer on the metal surface played a shielding role. Due to the extremely high adhesion of the coating, it is impossible to peel off the coating. It can be speculated that the metal inside is tightly adhered to the coating and no rust has occurred. In summary, all coatings can still be tightly adhered to the surface of the metal substrate after 1000 hours of salt spray testing. The addition of the composite material of graphene, carbon nanotubes and secondary doped polyaniline greatly enhances the corrosion resistance of the coating. And perhaps because the coating is more effective, it will take longer to observe the difference in the salt spray test.

[0092] Figure 11 Metallographic images of coatings prepared at varying addition levels of the graphene / carbon nanotube / secondary doped polyaniline composite material after 1800 hours of immersion. Magnified 400x, the images show a moderate change in the coating's density with increasing addition levels of the composite material. At a 3% addition level, a distinct heterogeneous structure is evident within the resulting film. With increasing addition levels, the heterogeneous structure transforms from a scattered, dotted structure to a flaky morphology. This indicates that increasing the addition level of the composite material decreases the coating's compatibility and uniformity, altering the film's structure and density, leading to reduced barrier and corrosion resistance. At a 0.1% addition level, the coating exhibits virtually no change. Therefore, the appropriate addition amount of the composite material of graphene, carbon nanotubes and secondary doped polyaniline can not only improve the corrosion resistance of the coating through the anti-pitting and passivation effects of the polyaniline composite material, but also needs to take into account not destroying the density of the coating.

[0093] The four pigments and fillers selected in the embodiment of the present invention are barium sulfate, ceramic powder, mica iron oxide, and calcium exchanged SiO2, among which barium sulfate and ceramic powder are used as fillers, and mica iron oxide and calcium exchanged SiO2 are used as functional fillers. The ratio of film-forming material to pigments and fillers, the ratio of fillers to rust-proof fillers, the ratio of barium sulfate to ceramic powder, and the ratio of mica iron oxide to calcium exchanged SiO2 are selected to design a four-factor three-level L9 (34) orthogonal experiment, as shown in Table 4.

[0094] Table 4 Formulation orthogonal experiment table

[0095]

[0096] Preparation method: First, add the active diluent to the epoxy resin in an appropriate proportion and disperse evenly at 1500 rpm for 5 minutes. Then, add the four pigments and fillers to the mixture in the corresponding proportions, add the dispersant, adjust the speed to 2500 rpm and continue stirring for 5 minutes. Finally, add the additives and stir for 1 hour to evenly disperse them. Grind the mixture three times using a three-roll mill to a fineness of less than 40 μm. After cooling, bucket it. Component A is now ready.

[0097] To ensure that the coating adheres fully to the surface substrate, a Q235 iron plate (150mm×75mm) must be degreased, dusted, and polished with 400-grit sandpaper before application. The surface must then be cleaned with ethanol and dried for later use. Component A and curing agent are mixed evenly in a mass ratio of 1:2.5-3.5 and applied to the treated substrate surface by brushing or roller coating. The coating thickness should be 630±30μm. Dry at room temperature for 7 days until fully cured before conducting basic physical tests, AC impedance tests, and neutral salt spray tests.

[0098] Table 5 Basic physical properties of compound pigment and filler coating

[0099]

[0100] Table 5 shows the basic physical properties of the composite pigment-filler coatings. It can be seen that the composite coatings all exhibit excellent physical properties. This is because the pigments and fillers used are all above 1000 mesh, and the fineness of the coatings is controlled to within 40μm after repeated grinding, resulting in a smoother and denser coating surface after brush application. The solids content of the coatings remains above 98%, meeting low VOC emission standards, and the thickness is controlled within 600±30μm, ensuring that any differences in coating performance are not due to differences in film thickness. The adhesion of the coatings remains above 12 MPa across the board. There are differences in the three physical properties of the coatings: wear resistance, impact resistance, and hardness. Samples 3, 6, and 9 show that the wear resistance of the coatings gradually improves with increasing filler content. The impact height is also the highest at each pigment-to-binder ratio, and the abrasion loss of sample 6 is kept below 10 mg. The viscosity of the nine samples varies greatly, which is closely related to the ratio of film-forming substances to pigments and fillers. When the ratio of film-forming substances to pigments and fillers is 6:4, the viscosity of the coating reaches about 9500mPa·s, while when the ratio of film-forming substances to pigments and fillers is 8:2, the viscosity of the coating is only about 7000mPa·s. Most of the components in the coating are still mainly flowing resins. And under the same pigment-to-base ratio, it can be seen that the viscosity of samples 3, 5, and 7 is also higher in their respective gradients. This is because as the proportion of ceramic powder increases, the oil absorption value of ceramic powder is much greater than that of the other three pigments and fillers, reaching 75g / 100g, requiring more film-forming substances to disperse, thereby increasing the viscosity of the coating. In summary, the samples after compounding all exhibit relatively excellent physical properties.

[0101] Table 6 Impedance fitting results of composite pigment and filler coating

[0102]

[0103] Table 7 Range analysis results

[0104]

[0105]

[0106] Figures 12 to 16 The Nyquist and Bode plots of the composite pigment and filler coatings with different proportions were measured after being immersed in 3.5% NaCl solution for 24h, 168h, 360h, 720h, and 1800h. Table 6 shows the impedance results of the composite pigment and filler obtained by ZsimpleWin software fitting. It can be seen from the figure that all samples have complete impedance arcs, and Figure 12-A shows that the impedance arc radius is relatively large, and the 12-a Bode diagram shows that at the beginning of immersion, the impedance values ​​of all samples are much higher than 1010Ω·cm 2 , which can provide good protection for the metal substrate. As shown in Table 6, at the beginning of immersion, the impedance value of sample No. 4 has reached 16.535×1010Ω·cm 2 , which is greater than the impedance value of the sample prepared by a single pigment filler. This may be due to the synergistic effect of micaceous iron oxide and calcium exchanged SiO2. The continuous accumulation of the lamellar structure of micaceous iron oxide and the reaction of calcium exchanged SiO2 with the corrosive medium in the corrosive environment make the free calcium ions react with the metal substrate to form a metal passivation film. The synergistic effect of the two makes the metal surface have layers of protection, and it is extremely difficult for the corrosive medium to penetrate into the coating.

[0107] After comparison, it can be seen that with the increase of immersion time, the impedance arc radius corresponding to all coatings is decreasing, and the Bode diagram also decreases. After immersion for 1800h, the impedance of sample No. 4 can still be maintained at 3.47×1010Ω·cm 2 The coating is still not penetrated and still maintains good shielding performance. This is because the content of micaceous iron oxide in this formula is the highest. Micaceous iron oxide has a good shielding effect. The wave plate particles in micaceous iron oxide overlap and accumulate layer by layer, thereby hindering the diffusion of moisture and corrosive media, extending the time for corrosive media to penetrate the coating, and achieving a long-term anti-corrosion effect. The resistance of sample No. 8 has dropped to 2.12×109Ω·cm 2 This is because the resin content is too high and the anti-rust filler is too low. Compared with sample No. 4, water molecules are relatively easy to penetrate into the coating and contact the metal to form micro-batteries. Although the impedance arc radius has decreased after a long period of immersion, the coating still maintains 109Ω·cm 2 The above experiments show that after long-term immersion, the impedance of all coatings did not drop below 106 and fail. All composite coatings had good anti-corrosion effects, and the impedance of the coating with the best ratio remained above 1010, thus achieving a long-term and effective anti-corrosion effect.

[0108] The range analysis results in Table 7 show that the order of influence of the factors in the orthogonal experiment on the AC impedance fitting results is epoxy resin / pigment filler > filler / anti-rust filler > ceramic powder / barium sulfate > micaceous iron oxide / calcium-exchanged SiO2. When the film-forming material:filler ratio is 6:4; filler:anti-rust filler ratio is 1:1; ceramic powder:barium sulfate ratio is 2:1; and micaceous iron oxide:calcium-exchanged SiO2 ratio is 3:1, the coating not only exhibits excellent physical properties but also provides long-term corrosion protection.

[0109] like Figure 17As shown in the figure, the coating prepared by compound pigments and fillers was immersed in 3.5% NaCl solution for 1800 hours, and the AC impedance test was performed. The corresponding equivalent circuit model was used to fit the EIS, with the immersion time as the horizontal axis and the resistance value of the fitted coating as the vertical axis, to plot the change of the resistance of the coating prepared by different compound pigments and fillers over time. Figure 17 It can be seen that the resistance of the coating decreases with the extension of the immersion time, and its impedance value decreases very quickly at the beginning of the immersion. It can also be clearly seen that the impedance values ​​of samples 7, 8, and 9 at the beginning of the immersion are significantly lower than those of other coatings. This is because the coatings corresponding to these three samples contain a large proportion of film-forming substances and too few pigments and fillers, which makes it impossible to form a dense protective film and is easily penetrated by corrosive media. As the immersion time increases, it can be seen that at around 400h, the impedance value of the coating decreases relatively slowly, and the coating system gradually stabilizes. The coating maintains a good anti-corrosion effect for a long time. This is because the calcium exchange SiO2 in all coatings plays a role. As the corrosive medium penetrates, its free calcium ions react with the metal to passivate, forming a dense protective film on the metal surface that provides good protection for the metal substrate. Generally speaking, when the impedance value of the coating is greater than 108Ω·cm 2 The coating has a good anti-corrosion effect. When the impedance value of the coating is less than 106Ω·cm 2 When the coating is completely ineffective, the corrosive medium has completely penetrated the coating. As can be seen from the figure, all coatings still maintain a temperature above 109 after immersion for 1800 hours, indicating that the coating still has a good anti-corrosion effect.

[0110] Figures 18 to 20 The pictures of the sample panels painted with compound pigments and fillers were taken after 72 hours, 360 hours, and 720 hours in the salt spray test chamber. Because the anti-rust filler used is mica iron oxide, the sample panels are dark red and have a certain covering power on the metal substrate. By comparing, it can be found that the corrosion conditions of the 9 samples are very different. Figure 20As can be seen from the figure, after 72 hours of salt spray testing, the first 6 samples did not change much, while samples 7, 8, and 9 began to show corrosion at the scratches. This is because the ratio of film-forming material to pigments and fillers in these three samples is 8:2, and the main component is resin, which does not provide good rust prevention for the metal substrate. After 360 hours, it can be seen that sample No. 3 has bubbling, sample No. 6 has rust in the scratch area, and samples 7, 8, and 9 have more serious corrosion. The remaining samples still have no changes, and the corrosion resistance of the coating remains at a very high level. In the pictures taken at 720 hours, it can be seen that the last three samples have shown very serious corrosion, and sample No. 8 has bubbled and caused the coating to bulge, proving that the amount of pigments and fillers added plays a significant role in the rust prevention ability of the coating. When compared at the same gradient (for example, 1, 2, 3 or 4, 5, 6), when the ratio of film-forming material to pigment is fixed, and the ratio of functional filler to anti-rust filler is 1:1, the coating can achieve the best anti-corrosion effect. And when comparing the three samples 4, 5, and 6, it can be found that sample No. 4 is the most complete, and is basically consistent with the picture just put into the salt spray test chamber, which provides long-term protection for the metal substrate, which is consistent with the AC impedance test results.

[0111] Figure 21 The metallographic photographs of the composite pigment-filled coating were taken after 1800 hours of immersion, with a magnification of 400 times. It can be seen that compared with the single pigment-filled coating, all coatings have a dense coating of micaceous iron oxide and calcium-exchanged SiO2. The first six pictures are not much different. The layers of coating are stacked very densely, making it difficult for corrosive media to penetrate. Especially in the fourth picture, there is no crack on the coating surface. The last three pictures show the appearance of heterogeneous structure on the coating surface. This is because the pigment-filled coating accounts for a small proportion in the coating formula, and the main component of the coating is still resin. After long-term immersion, the coating is penetrated by water molecules and corrosive media, leaving traces, and cannot provide long-term protection for the metal. The results are consistent with the salt spray test.

[0112] The present invention provides a method for preparing a nano-carbon and secondary doped polyaniline composite solvent-free coating, wherein an intrinsic polyaniline-graphene composite material and an intrinsic polyaniline-carbon nanotube composite material are respectively added to a 1 mol / L doping acid solution in a mass ratio of 1:1, and a polyaniline secondary doping method is adopted to prepare a composite material of graphene, carbon nanotubes and secondary doped polyaniline, thereby solving the agglomeration and dispersion problems of polyaniline and having excellent corrosion inhibition performance; the composite material product of the graphene, carbon nanotubes and secondary doped polyaniline after secondary mixing and doping has more uniform morphology and more uniform nanofibers. Among them, by controlling the ratio of graphene to aniline and the ratio of carbon nanotubes to aniline, the product morphology is improved, and the carbon nanotubes wrapped with polyaniline are neatly arranged on the graphene surface with uniform size and a fiber length of more than 800nm; a composite material of graphene, carbon nanotubes and secondary doped polyaniline is prepared by a secondary doping method of polyaniline, which avoids the agglomeration problem of the graphene and carbon nanotubes themselves and effectively improves the various performances of the product. The performance is better than that of the product obtained by single doping or secondary doping of graphene or carbon nanotubes alone. When applied to solvent-free epoxy coatings, a solvent-free epoxy coating with excellent comprehensive performance is obtained.

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a nanocarbon and secondary doped polyaniline composite solvent-free coating, characterized in that: The method comprises: Adding a reactive diluent in a mass percentage of 6% to 8% to the epoxy resin, and uniformly dispersing the mixture at a rotation speed of 1200 to 1600 r / min for 3 to 8 minutes to prepare an epoxy resin mixture; Add ceramic powder, barium sulfate, micaceous iron oxide and calcium exchanged SiO2 to the epoxy resin mixture in the following order: the mass ratio of filler to anti-rust filler is 1:1, the mass ratio of ceramic powder to barium sulfate is 2:1, and the mass ratio of micaceous iron oxide to calcium exchanged SiO2 is 3:

1. After adding the dispersant, adjust the speed to 2000-2600 r / min and continue stirring for 3-8 minutes; The composite material of graphene, carbon nanotubes and secondary doped polyaniline is added to the mixture at a ratio of 0.1% to 3%, and finally 1% to 2% of additives are added. After stirring for 1 hour to make it uniformly dispersed, it is ground three times with a three-roll grinder to make its fineness less than 40μm. After cooling, a nanocarbon and secondary doped polyaniline composite solvent-free coating is prepared. The composite material of graphene, carbon nanotubes and secondary doped polyaniline is prepared by the following method: (1) Take two equal volumes of 1 mol / L doped acid solution and add aniline-graphene mixture and ammonium persulfate respectively, wherein the molar ratio of aniline-graphene mixture to ammonium persulfate is 0.8:1, and mix the two evenly with a magnetic stirrer for 1-2 h. Place them at room temperature and let them stand for 20-26 h. The obtained product is washed with ethanol and deionized water to neutrality, and then dried and ground to obtain a primary doped polyaniline-graphene composite material; wherein the mass ratio of aniline to graphene in the aniline-graphene mixture is 15-25:1; (2) Adding excess ammonia water to the primary doped polyaniline-graphene composite material for dedoping, stirring with a magnetic stirrer for 1-2 h, and standing at room temperature for 20-26 h. The obtained product is washed with ethanol and deionized water until neutral, and finally dried and ground to obtain the intrinsic polyaniline-graphene composite material; (3) Take two equal volumes of 1 mol / L doped acid solution and add aniline-carbon nanotube mixture and ammonium persulfate respectively, wherein the molar ratio of aniline-carbon nanotube mixture to ammonium persulfate is 0.8:1, and mix the two evenly with a magnetic stirrer for 1-2 h. Place them at room temperature and let them stand for 20-26 h. The obtained product is washed with ethanol and deionized water to neutrality, and then dried and ground to obtain a primary doped polyaniline-carbon nanotube composite material; wherein the mass ratio of aniline to carbon nanotubes in the aniline-carbon nanotube mixture is 15-25:1; (4) Adding excess ammonia water to the primary doped polyaniline-carbon nanotube composite material for dedoping, stirring with a magnetic stirrer for 1-2 h, and standing at room temperature for 20-26 h. The obtained product is washed with ethanol and deionized water until neutral, and finally dried and ground to obtain the intrinsic polyaniline-carbon nanotube composite material; (5) The intrinsic polyaniline-graphene composite material and the intrinsic polyaniline-carbon nanotube composite material were added to a 1 mol / L doped acid solution in a mass ratio of 1:1, mixed and stirred, and allowed to stand for 20 to 26 h. They were then filtered and washed with ethanol and deionized water in sequence until neutral. Finally, they were dried and ground to obtain a composite material of graphene, carbon nanotubes and secondary doped polyaniline, wherein the mass ratio of aniline to graphene in the aniline-graphene mixture was equal to the mass ratio of aniline to carbon nanotubes in the aniline-carbon nanotube mixture.

2. The method according to claim 1, characterized in that The mass ratio of aniline to graphene in the aniline-graphene mixture is 18-22:1, and the mass ratio of aniline to carbon nanotubes in the aniline-carbon nanotube mixture is 18-22:

1.

3. The method according to claim 1, characterized in that The mass ratio of aniline to graphene in the aniline-graphene mixture is 20:1, and the mass ratio of aniline to carbon nanotubes in the aniline-carbon nanotube mixture is 20:

1.

4. The method according to claim 1, wherein The composite material of graphene, carbon nanotubes and secondary doped polyaniline is added to the mixture at a ratio of 0.1% to 3% as follows: The composite material of graphene, carbon nanotubes and secondary doped polyaniline is added to the mixture at a ratio of 1% to 3%.

5. The method according to claim 1, wherein The composite material of graphene, carbon nanotubes and secondary doped polyaniline is added to the mixture at a ratio of 0.1% to 3% as follows: The composite material of graphene, carbon nanotubes and secondary doped polyaniline is added to the mixture at a ratio of 1% to 2%.

6. The method according to claim 1, wherein The composite material of graphene, carbon nanotubes and secondary doped polyaniline is added to the mixture at a ratio of 0.1% to 3% as follows: The composite material of graphene, carbon nanotubes and secondary doped polyaniline is added to the mixture at a ratio of 0.5% to 1%.

7. The method according to claim 1, characterized in that The corrosion inhibition efficiency of the prepared composite material of graphene, carbon nanotubes and secondary doped polyaniline is greater than 80%, and the impedance value of the prepared composite material of graphene, carbon nanotubes and secondary doped polyaniline is greater than 1800 Ω*cm2.

8. The method according to claim 1, characterized in that The fiber length of the prepared composite material of graphene, carbon nanotube and secondary doped polyaniline is greater than 800nm.

9. The method according to claim 1, characterized in that The fiber length of the prepared composite material of graphene, carbon nanotube and secondary doped polyaniline is greater than 850nm.

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