Graphene-based anticorrosive coating and preparation method thereof

Abstract

The application discloses a graphene-based anticorrosive paint and a preparation method thereof, and relates to the technical field of paints.The graphene-based anticorrosive paint is prepared by the following steps: reacting dimethyl dimethoxysilane, functionalized dimethoxysiloxane and 3-aminopropyl dimethoxymethyl silane to obtain a functionalized siloxane oligomer; reacting castor oil and epichlorohydrin to obtain modified castor oil; hydrothermally reacting graphene oxide and cerous nitrate to obtain pre-modified graphene; reacting sodium lignosulfonate, formaldehyde and tetraethylenepentamine and coating the pre-modified graphene to obtain modified graphene; and uniformly mixing epoxy resin, the modified castor oil, the functionalized siloxane oligomer, the modified graphene, isophorone diamine and acetone to obtain the graphene-based anticorrosive paint.The graphene-based anticorrosive paint prepared by the application has excellent flame-retardant, anticorrosive and self-repairing properties.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coating technology, in particular to a graphene-based anticorrosive coating and a preparation method thereof. BACKGROUND

[0002] Corrosion, as a common phenomenon, widely exists in industrial production and daily life, involving many fields such as infrastructure transportation, energy equipment, production and manufacturing, and public utilities. The economic loss caused by corrosion each year is very huge, and the problems caused by metal corrosion cannot be ignored. Metal corrosion refers to the phenomenon that metal materials are damaged by chemical or electrochemical action with the surrounding medium (sea water, atmosphere, acid, alkali, etc.) under physical, mechanical or biological factors. There are four main metal corrosion protection technologies, namely, designing corrosion-resistant alloy, electrochemical protection, corrosion inhibitor protection and organic coating protection. Among them, the organic coating technology is widely used in the field of corrosion protection due to its simple preparation, low cost and outstanding effect.

[0003] However, organic coatings are prone to defects such as micropores and cracks during curing and use, and H2O, O2, Cl - Corrosive media penetrate the metal substrate through defects, accelerating the corrosion of the damaged part, thereby greatly shortening the service life of the coating. Therefore, the development of self-repairing anticorrosive coating technology is particularly important. After the coating surface is damaged, the damaged part is repaired by physical or chemical change, prolonging the service life of the coating and greatly reducing the cost of metal corrosion protection. SUMMARY

[0004] The present application relates to the field of coating technology, in particular to a graphene-based anticorrosive coating and a preparation method thereof.

[0005] In order to solve the above technical problems, the present application provides the following technical scheme:

[0006] A graphene-based anticorrosive coating is prepared by reacting dimethyldimethoxysilane, functionalized dimethoxysiloxane and 3-aminopropyl dimethoxymethylsilane to obtain a functionalized siloxane oligomer; reacting sodium lignosulfonate, formaldehyde and tetraethylenepentamine and coating on pre-modified graphene to obtain modified graphene; and uniformly mixing epoxy resin, modified castor oil, functionalized siloxane oligomer, modified graphene, isophorone diamine and acetone to obtain the graphene-based anticorrosive coating.

[0007] The functionalized dimethoxysiloxane is prepared by reacting 3-glycidyl ether oxypropyl dimethoxymethylsilane and 4-amino-2,2,6,6-tetramethylpiperidine-1-oxide.

[0008] The modified castor oil is prepared by reacting castor oil and epichlorohydrin.

[0009] The pre-modified graphene is prepared by hydrothermal reaction of graphene oxide and cerium nitrate.

[0010] The preparation method of the graphene-based anticorrosive coating comprises the following preparation steps:

[0011] (1) uniformly mix dimethyl dimethoxysilane, functionalized dimethoxysiloxane and 3-aminopropyl dimethoxymethyl silane at a molar ratio of 1:(0.5-0.6):(0.3-0.4), then add barium hydroxide with a mass of 0.03-0.05 times that of the dimethyl dimethoxysilane, and stir at 200-300 r / min at 78-82°C for 5-6 h under nitrogen protection, and dry at 56-60°C for 4-6 h under vacuum to obtain a functionalized siloxane oligomer;

[0012] (2) uniformly mix castor oil, epichlorohydrin and toluene, and stir at 200-300 r / min at 30-40°C for 20-30 min, then add triethylamine with a mass of 0.03-0.05 times that of the castor oil, heat to 55-65°C, and continue to stir for 3-4 h, wash with an equal volume of toluene and deionized water for 3-5 times, take the organic phase, and dry at 50-60°C for 7-8 h under vacuum to obtain modified castor oil;

[0013] (3) uniformly mix pre-modified graphene, sodium lignosulfonate and deionized water, add tetraethylenepentamine with a mass of 2-2.2 times that of the sodium lignosulfonate, and add a formaldehyde aqueous solution with a mass of 0.8-1 times that of the sodium lignosulfonate, and stir at 200-300 r / min at 88-92°C for 7-8 h, filter, wash with anhydrous ethanol and deionized water for 3-5 times each, and dry at 60-70°C for 8-9 h under vacuum to obtain modified graphene;

[0014] (4) take epoxy resin 24-26 parts, modified castor oil 18-20 parts, functionalized siloxane oligomer 10-12 parts, modified graphene 2-3 parts, isophorone diamine 6-8 parts and acetone 20-22 parts by mass fraction; uniformly mix the epoxy resin, modified castor oil, functionalized siloxane oligomer, modified graphene, isophorone diamine and acetone to obtain a graphene-based anticorrosive coating.

[0015] As optimization, the preparation method of the functionalized dimethoxysiloxane in step (1) is: 3-glycidyl ether oxypropyl dimethoxymethyl silane, 4-amino-2, 2, 6, 6-tetramethyl piperidine-1-oxide are added into 8-10 times of the mass of 3-glycidyl ether oxypropyl dimethoxymethyl silane of tetrahydrofuran at 58-62 DEG C, and stirred at 200-300 r / min for 3-4 h, and dried at 58-62 DEG C under vacuum condition for 7-8 h to obtain the functionalized dimethoxysiloxane.

[0016] As optimization, the mass ratio of castor oil, epichlorohydrin and toluene in step (2) is 1:(0.4-0.6):(8-10).

[0017] As optimization, the preparation method of the pre-modified graphene in step (3) is: cerium nitrate, polyvinylpyrrolidone, deionized water and anhydrous ethanol are uniformly mixed, and then the mixture is stirred at 10-30 DEG C and 200-300 r / min for 50-60 min, 4-5 times of the mass of the graphene oxide is added, and the mixture is continuously stirred at 200-300 r / min for 2-3 h, and then the mixture is placed in a high-pressure reaction kettle and stirred at 118-122 DEG C and 200-300 r / min for 22-24 h, and then the mixture is filtered, washed with anhydrous ethanol and deionized water for 3-5 times, and dried at 70-80 DEG C under vacuum condition for 8-9 h to obtain the pre-modified graphene.

[0018] As optimization, the type of the polyvinylpyrrolidone is PVP-K30.

[0019] As optimization, the mass ratio of the cerium nitrate, polyvinylpyrrolidone, deionized water and anhydrous ethanol is 1:(1.2-1.4):(90-100):(260-280).

[0020] As optimization, the mass ratio of the pre-modified graphene, sodium lignosulfonate and deionized water in step (3) is 1:(3-4):(200-220).

[0021] As optimization, the mass fraction of the formaldehyde aqueous solution in step (3) is 37%.

[0022] As optimization, the type of the epoxy resin in step (4) is E51.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] The application is in the preparation of graphene-based anticorrosive coating, 3-glycidyl ether oxypropyl dimethoxymethyl silane and 4-amino-2,2,6,6-tetramethylpiperidine-1-oxide are reacted to prepare functional dimethoxysiloxane; dimethyldimethoxysilane, functional dimethoxysiloxane and 3-aminopropyl dimethoxymethyl silane are reacted to prepare functional siloxane oligomer; castor oil and epichlorohydrin are reacted to prepare modified castor oil; graphene oxide and cerium nitrate are hydrothermally reacted to prepare pre-modified graphene; sodium lignosulfonate, formaldehyde and tetraethylenepentamine are reacted and coated on the pre-modified graphene to prepare modified graphene; epoxy resin, modified castor oil, functional siloxane oligomer, modified graphene, isophorone diamine and acetone are uniformly mixed to prepare graphene-based anticorrosive coating.

[0025] First, 3-glycidyl ether oxypropyl dimethoxymethyl silane and 4-amino-2,2,6,6-tetramethylpiperidine-1-oxide are reacted to prepare functional dimethoxysiloxane; dimethyldimethoxysilane, functional dimethoxysiloxane and 3-aminopropyl dimethoxymethyl silane are reacted to prepare functional siloxane oligomer; amino and nitroxyl radical are introduced on the side chain of the functional siloxane oligomer molecule, the nitroxyl radical reacts with the carbon-carbon double bond on the modified castor oil to form an alkoxy amine bond; the alkoxy amine bond is a thermally reversible bond that can be broken again to form growing chain active radicals and nitroxyl stable radicals at high temperature, and when the system temperature returns to room temperature, the growing chain active radicals and nitroxyl stable radicals combine to form an alkoxy amine bond again, the introduction of the alkoxy amine bond with thermal reversible reaction characteristics into the graphene-based anticorrosive coating can break and recombine the alkoxy amine bond through heating after the coating is damaged, realizing the repair of the graphene-based anticorrosive coating, and endowing the graphene-based anticorrosive coating with self-repairing performance, and the reaction mechanism is as follows:

[0026] The amino group introduced on the siloxane oligomer can react with the epoxy group to participate in the curing process of the coating, introducing Si-O-Si in the coating and improving the flame retardant performance of the graphene-based anticorrosive coating.

[0027] Secondly, the castor oil, epoxy chloropropane reaction is prepared modified castor oil; the epoxy group is introduced on the modified castor oil, so that the modified castor oil can participate in the curing process of the coating, the carbon-carbon double bond on the castor oil can react with the nitroxide radical on the functionalized siloxane oligomer to generate an alkoxyamine bond, the alkoxyamine bond is a thermally reversible bond, which can be broken again to generate growing chain active radicals and nitroxide stable radicals at high temperature, and when the system temperature returns to normal temperature, the growing chain active radicals and nitroxide stable radicals combine to generate the alkoxyamine bond again, the alkoxyamine bond with the property of thermal reversible reaction is introduced into the graphene-based anticorrosive coating, so that the alkoxyamine bond can be broken and recombined by heating after the coating is damaged, the graphene-based anticorrosive coating is repaired, and the graphene-based anticorrosive coating is endowed with the self-repairing performance.

[0028] Finally, the pre-modified graphene is prepared by hydrothermal reaction of graphene oxide and cerium nitrate, and cerium oxide is loaded on the pre-modified graphene. When the corrosion medium penetrates into the coating, the free cerium ions generated by the cerium oxide react with OH - Form insoluble oxide deposits on the metal surface, hinder the redox reaction in the deposition area, inhibit the cathode reaction rate, and thus improve the corrosion resistance of the coating; the modified graphene is prepared by reacting sodium lignosulfonate, formaldehyde and tetraethylenepentamine and coating on the pre-modified graphene; the sulfonyl and phenolic hydroxyl groups contained in the sodium lignosulfonate and the amino groups contained in the tetraethylenepentamine can be complexed with the surface of the metal substrate, thereby enhancing the adhesion between the coating and the metal substrate and playing a good barrier effect and corrosion protection effect. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0030] The type of epoxy resin used in the examples and comparative examples is E51.

[0031] Example 1:

[0032] A preparation method of a graphene-based anticorrosive coating, the preparation method of the graphene-based anticorrosive coating comprises the following preparation steps:

[0033] (1) 3-glycidyloxypropyldimethoxymethylsilane, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxide were added into 8 times of 3-glycidyloxypropyldimethoxymethylsilane in tetrahydrofuran at a molar ratio of 1:1, and stirred at 58°C and 200 r / min for 4 h. Then, the functional dimethoxysiloxane was prepared by drying at 58°C under vacuum for 8 h. Dimethyldimethoxysilane, functional dimethoxysiloxane, and 3-aminopropyldimethoxymethylsilane were mixed uniformly at a molar ratio of 1:0.5:0.3. Then, 0.03 times of barium hydroxide based on the mass of dimethyldimethoxysilane was added, and the mixture was stirred at 78°C and 200 r / min for 6 h under nitrogen protection. Finally, the functional siloxane oligomer was prepared by drying at 56°C under vacuum for 6 h.

[0034] (2) Castor oil, epichlorohydrin, and toluene were mixed uniformly at a mass ratio of 1:0.4:8, and stirred at 30°C and 200 r / min for 30 min. Then, 0.03 times of triethylamine based on the mass of castor oil was added, and the temperature was raised to 55°C. The mixture was continuously stirred for 4 h. The organic phase was obtained by washing with an equal volume of toluene and deionized water three times, and drying at 50°C under vacuum for 8 h to obtain the modified castor oil.

[0035] (3) Cerium nitrate, polyvinylpyrrolidone, deionized water, and anhydrous ethanol were mixed uniformly at a mass ratio of 1:1.2:90:260, and stirred at 10°C and 200 r / min for 60 min. Then, 4 times of graphene oxide based on the mass of cerium nitrate was added, and the mixture was continuously stirred for 3 h. The pre-modified graphene was prepared by stirring at 118°C and 200 r / min for 24 h in a high-pressure reaction kettle, filtering, washing with anhydrous ethanol and deionized water three times each, and drying at 70°C under vacuum for 9 h. The pre-modified graphene, sodium lignosulfonate, and deionized water were mixed uniformly at a mass ratio of 1:3:200. Then, 2 times of tetraethylenepentamine based on the mass of sodium lignosulfonate was added, and 0.8 times of 37% formaldehyde aqueous solution based on the mass of sodium lignosulfonate was added. The mixture was stirred at 88°C and 200 r / min for 8 h. The modified graphene was obtained by filtering, washing with anhydrous ethanol and deionized water three times each, and drying at 60°C under vacuum for 9 h.

[0036] (4) Epoxy resin 24 parts, modified castor oil 18 parts, functional siloxane oligomer 10 parts, modified graphene 2 parts, isophorone diamine 6 parts, and acetone 20 parts were mixed uniformly to obtain the graphene-based anticorrosive coating.

[0037] Example 2:

[0038] The application discloses a preparation method of a graphene-based anticorrosive coating.

[0039] (1) 3-glycidyloxypropyldimethoxymethylsilane and 4-amino-2,2,6,6-tetramethylpiperidine-1-oxide are added into tetrahydrofuran with a mass of 9 times that of the 3-glycidyloxypropyldimethoxymethylsilane at a molar ratio of 1:1, and then stirred at 60 DEG C and 250 r / min for 3.5 h, and dried at 60 DEG C under vacuum for 7.5 h to obtain a functionalized dimethoxysiloxane; dimethyldimethoxysilane, the functionalized dimethoxysiloxane and 3-aminopropyldimethoxymethylsilane are uniformly mixed at a molar ratio of 1:0.55:0.35, and then barium hydroxide with a mass of 0.04 times that of the dimethyldimethoxysilane is added, and then stirred at 80 DEG C and 250 r / min for 5.5 h under nitrogen protection, and dried at 58 DEG C under vacuum for 5 h to obtain a functionalized siloxane oligomer;

[0040] (2) castor oil, epichlorohydrin and toluene are uniformly mixed at a mass ratio of 1:0.5:9, and then stirred at 35 DEG C and 250 r / min for 25 min, and then triethylamine with a mass of 0.04 times that of the castor oil is added, and then the temperature is increased to 60 DEG C, and then stirring is continued for 3.5 h, and then the mixture is washed with a mixture of toluene and deionized water with equal volume for 4 times, and then the organic phase is taken out, and then dried in a drying box under vacuum at 55 DEG C for 7.5 h to obtain modified castor oil;

[0041] (3) cerium nitrate, polyvinylpyrrolidone, deionized water and anhydrous ethanol are uniformly mixed at a mass ratio of 1:1.3:95:270, and then stirred at 20 DEG C and 250 r / min for 55 min, and then graphene oxide with a mass of 4.5 times that of the cerium nitrate is added, and then stirring is continued for 2.5 h, and then the mixture is placed in a high-pressure reaction kettle, and then stirred at 120 DEG C and 250 r / min for 23 h, and then filtered, and then washed with anhydrous ethanol and deionized water for 4 times respectively, and then dried at 75 DEG C under vacuum for 8.5 h to obtain pre-modified graphene; the pre-modified graphene, sodium lignosulfonate and deionized water are uniformly mixed at a mass ratio of 1:3.5:210, and then tetraethylenepentamine with a mass of 2.1 times that of the sodium lignosulfonate is added, and then a formaldehyde aqueous solution with a mass fraction of 37% with a mass of 0.9 times that of the sodium lignosulfonate is added, and then stirred at 90 DEG C and 250 r / min for 7.5 h, and then filtered, and then washed with anhydrous ethanol and deionized water for 4 times respectively, and then dried at 65 DEG C under vacuum for 8.5 h to obtain modified graphene;

[0042] (4) by mass fraction, take 25 parts of epoxy resin, 19 parts of modified castor oil, 11 parts of functionalized siloxane oligomer, 2.5 parts of modified graphene, 7 parts of isophorone diamine, 21 parts of acetone; the epoxy resin, modified castor oil, functionalized siloxane oligomer, modified graphene, isophorone diamine, acetone are mixed uniformly to prepare graphene-based anticorrosive coating.

[0043] Example 3:

[0044] A preparation method of a graphene-based anticorrosive coating, the preparation method of the graphene-based anticorrosive coating comprises the following preparation steps:

[0045] (1) 3-glycidyl ether oxypropyl dimethoxymethyl silane, 4-amino-2,2,6,6-tetramethyl piperidine-1-oxide are added to 10 times the mass of 3-glycidyl ether oxypropyl dimethoxymethyl silane in tetrahydrofuran at a molar ratio of 1:1, stirred at 62℃, 300r / min for 3h, dried at 62℃ under vacuum for 7h to obtain functionalized dimethoxysiloxane; dimethyldimethoxysilane, functionalized dimethoxysiloxane, 3-aminopropyl dimethoxymethyl silane are mixed uniformly at a molar ratio of 1:0.6:0.4, then 0.05 times the mass of dimethyldimethoxysilane is added to barium hydroxide, stirred at 82℃ under nitrogen protection, 300r / min for 5h, dried at 60℃ under vacuum for 4h to obtain functionalized siloxane oligomer;

[0046] (2) the castor oil, epichlorohydrin, toluene are mixed uniformly at a mass ratio of 1:0.6:10, stirred at 40℃, 300r / min for 20min, 0.05 times the mass of triethylamine is added to castor oil, heated to 65℃, continue to stir for 3h, washed with equal volume of toluene and deionized water for 5 times, take the organic phase, place in a drying oven, dried at 60℃ under vacuum for 7h to obtain modified castor oil;

[0047] (3) cerium nitrate, polyvinylpyrrolidone, deionized water, anhydrous ethanol were mixed uniformly according to the mass ratio of 1:1.4:100:280, stirred at 30℃ and 300r / min for 50min, 5 times the mass of cerium nitrate of graphene oxide was added, and stirring was continued for 2h, and then it was placed in a high-pressure reaction kettle and stirred at 122℃ and 300r / min for 22h, filtered, washed with anhydrous ethanol and deionized water for 5 times respectively, and dried at 80℃ under vacuum condition for 8h to obtain pre-modified graphene; the pre-modified graphene, sodium lignosulfonate and deionized water were mixed uniformly according to the mass ratio of 1:4:220, 2.2 times the mass of sodium lignosulfonate of tetraethylenepentamine was added, 1 times the mass of sodium lignosulfonate of 37% mass fraction formaldehyde aqueous solution was added, and stirring was carried out at 92℃ and 300r / min for 7h, then it was filtered, washed with anhydrous ethanol and deionized water for 5 times respectively, and dried at 70℃ under vacuum condition for 8h to obtain modified graphene;

[0048] (4) epoxy resin 26 parts, modified castor oil 20 parts, functionalized siloxane oligomer 12 parts, modified graphene 3 parts, isophorone diamine 8 parts, and acetone 22 parts were weighed according to the mass fraction; the epoxy resin, modified castor oil, functionalized siloxane oligomer, modified graphene, isophorone diamine and acetone were mixed uniformly to obtain a graphene-based anticorrosive coating.

[0049] Comparative Example 1:

[0050] The preparation method of the graphene-based anticorrosive coating of Comparative Example 1 is different from that of Example 2 in that step (1) is modified as follows: dimethyl dimethoxy silane and 3-aminopropyl dimethoxy methyl silane were mixed uniformly according to the molar ratio of 1.55:0.35, 0.04 times the mass of barium hydroxide of dimethyl dimethoxy silane was added, stirring was carried out at 80℃ and 250r / min for 5.5h under nitrogen protection, and drying was carried out at 58℃ under vacuum condition for 5h to obtain a functionalized siloxane oligomer. The remaining steps are the same as those of Example 2.

[0051] Comparative Example 2:

[0052] The preparation method of the graphene-based anticorrosive coating of Comparative Example 2 is different from that of Example 2 in that step (1) is not performed, and step (4) is modified as follows: epoxy resin 25 parts, modified castor oil 19 parts, modified graphene 2.5 parts, isophorone diamine 18 parts, and acetone 21 parts were weighed according to the mass fraction; the epoxy resin, modified castor oil, modified graphene, isophorone diamine and acetone were mixed uniformly to obtain a graphene-based anticorrosive coating. The remaining steps are the same as those of Example 2.

[0053] Comparative Example 3:

[0054] The preparation method of the graphene-based anticorrosive coating of Comparative Example 3 is different from that of Example 2 in that step (2) is not performed, and step (4) is modified as follows: 44 parts by mass of epoxy resin, 11 parts by mass of functionalized siloxane oligomer, 2.5 parts by mass of modified graphene, 7 parts by mass of isophorone diamine, and 21 parts by mass of acetone are weighed, and then mixed uniformly to prepare the graphene-based anticorrosive coating. The remaining steps are the same as those of Example 2.

[0055] Comparative Example 4:

[0056] The preparation method of the graphene-based anticorrosive coating of Comparative Example 4 is different from that of Example 2 only in step (3), which is modified as follows: cerium nitrate, polyvinylpyrrolidone, deionized water, and anhydrous ethanol are uniformly mixed at a mass ratio of 1:1.3:95:270, stirred at 20℃ and 250r / min for 55min, 4.5 times the mass of cerium nitrate of graphene oxide is added, and stirring is continued for 2.5h, placed in a high-pressure reaction kettle, stirred at 120℃ and 250r / min for 23h, filtered, washed with anhydrous ethanol and deionized water for 4 times respectively, and dried at 75℃ under vacuum conditions for 8.5h to prepare the modified graphene. The remaining steps are the same as those of Example 2.

[0057] Comparative Example 5:

[0058] The preparation method of the graphene-based anticorrosive coating of Comparative Example 5 is different from that of Example 2 only in step (3), which is modified as follows: graphene oxide, sodium lignosulfonate, and deionized water are uniformly mixed at a mass ratio of 1:3.5:210, 2.1 times the mass of sodium lignosulfonate of tetraethylenepentamine is added, 0.9 times the mass of sodium lignosulfonate of a 37% mass fraction formaldehyde aqueous solution is added, stirred at 90℃ and 250r / min for 7.5h, filtered, washed with anhydrous ethanol and deionized water for 4 times respectively, and dried at 65℃ under vacuum conditions for 8.5h to prepare the modified graphene.

[0059] Test Example 1

[0060] Test of self-repairing performance

[0061] Test method: The examples and comparative examples are poured into a polytetrafluoroethylene mold, heated at 150℃ for 20min, cooled to 60℃, heated for 30min, cooled to room temperature, and left to stand for 10h, demolded and taken out, prepared into a standard sample bar according to GB / T1040-92, and tested for tensile strength M. A 20mm-long and 3mm-deep crack is drawn in the middle of the standard sample bar, heated at 125℃ for 20min, cooled to room temperature, and left to stand for 5h to obtain a repaired sample, which is tested for tensile strength N, and the self-repairing rate of the examples and comparative examples is calculated; self-repairing rate=(N / M)×100%. The results are shown in Table 1.

[0062] Table 1

[0063] Self-repair rate (%) Self-repair rate (%) Example 1 94.67 Comparative Example 1 71.33 Example 2 95.18 Comparative Example 2 70.58 Example 3 95.04 Comparative Example 3 69.24 Comparative Example 4 94.38 Comparative Example 5 94.51

[0064] From the comparison of the experimental data of Examples 1-3 and Comparative Examples 1-5 in Table 1, it can be found that the graphene-based anticorrosive coating prepared by the present application has good self-repairing performance.

[0065] By comparison, the self-repairing rate of Examples 1-3 is greater than that of Comparative Examples 1-2, which indicates that the functionalized dimethoxysiloxane is prepared by reacting 3-glycidyloxypropyldimethoxymethylsilane and 4-amino-2,2,6,6-tetramethylpiperidine-1-oxide; the functionalized siloxane oligomer is prepared by reacting dimethyldimethoxysilane, the functionalized dimethoxysiloxane and 3-aminopropyldimethoxymethylsilane; the nitroxyl radical is introduced on the side chain of the functionalized siloxane oligomer, and the nitroxyl radical reacts with the carbon-carbon double bond on the modified castor oil to form an alkoxyamine bond; the alkoxyamine bond is a thermally reversible bond, which can be re-broken to generate growing chain active radicals and nitroxyl stable radicals at high temperature, and when the system temperature returns to room temperature, the growing chain active radicals and the nitroxyl stable radicals combine to form the alkoxyamine bond again. The introduction of the alkoxyamine bond with the thermal reversible reaction characteristic into the graphene-based anticorrosive coating can recombine the alkoxyamine bond by heating after the coating is damaged, so as to repair the graphene-based anticorrosive coating and endow the graphene-based anticorrosive coating with the self-repairing performance.

[0066] By comparison, the self-repairing rate of Examples 1-3 is greater than that of Comparative Example 3, which indicates that the modified castor oil is prepared by reacting castor oil and epichlorohydrin; the epoxy group is introduced on the modified castor oil, so that the modified castor oil can participate in the curing process of the coating, and the carbon-carbon double bond on the castor oil can react with the nitroxyl radical on the functionalized siloxane oligomer to form an alkoxyamine bond. The alkoxyamine bond is a thermally reversible bond, which can be re-broken to generate growing chain active radicals and nitroxyl stable radicals at high temperature, and when the system temperature returns to room temperature, the growing chain active radicals and the nitroxyl stable radicals combine to form the alkoxyamine bond again. The introduction of the alkoxyamine bond with the thermal reversible reaction characteristic into the graphene-based anticorrosive coating can recombine the alkoxyamine bond by heating after the coating is damaged, so as to repair the graphene-based anticorrosive coating and endow the graphene-based anticorrosive coating with the self-repairing performance.

[0067] Test Example 2

[0068] Test of anticorrosive performance

[0069] Test method: test according to GB / T1771 standard. The examples and comparative examples are uniformly coated on tinplate, and then heated at 150℃ for 20 min, cooled to 60℃, heated for 30 min, cooled to room temperature, and then left to stand for 10 h. A salt spray test chamber is started and 5% by mass sodium chloride aqueous solution is added into the chamber. After 24 h, the test plate is taken out of the chamber, washed with water, and then corrosion, rusting and damage are observed and recorded. The results are shown in Table 2.

[0070] Table 2

[0071] Salt spray resistance Salt spray resistance Example 1 No abnormality in paint film Comparative Example 1 No abnormality in paint film Example 2 No abnormality in paint film Comparative Example 2 No abnormality in paint film Example 3 No abnormality in paint film Comparative Example 3 No abnormality in paint film Comparative Example 4 Bubbling and cracking in paint film Comparative Example 5 Bubbling and cracking in paint film

[0072] It can be found from the experimental data of Examples 1-3 and Comparative Examples 1-5 in Table 2 that the graphene-based anticorrosive coating prepared in the application has good anticorrosive performance.

[0073] By comparison, the paint film of Examples 1-3 is intact, while the paint film of Comparative Example 4 shows bubbling and cracking, indicating that the modified graphene is prepared by reacting sodium lignosulfonate, formaldehyde and tetraethylenepentamine and coating on the pre-modified graphene. The sulfuryl group and phenolic hydroxyl group contained in sodium lignosulfonate, and the amino group contained in tetraethylenepentamine can complex with the surface of metal substrate, enhancing the adhesion between the coating and the metal substrate, and playing a good barrier effect and anticorrosive effect.

[0074] By comparison, the paint film of Examples 1-3 is intact, while the paint film of Comparative Example 5 shows bubbling and cracking, indicating that the pre-modified graphene is prepared by hydrothermal reaction of graphene oxide and cerium nitrate, and cerium oxide is loaded on the pre-modified graphene. When the corrosion medium penetrates into the coating, the free cerium ions generated by the cerium oxide combine with OH - Form insoluble oxides and deposit on the metal surface, hindering the redox reaction in the deposition area, inhibiting the cathodic reaction rate, thereby improving the corrosion resistance of the coating.

[0075] Test Example 3

[0076] Test of flame retardant performance

[0077] Test method: pour the examples and comparative examples into a polytetrafluoroethylene mold, heat at 150℃ for 20 min, cool to 60℃, heat for 30 min, cool to room temperature, stand for 10 h, demold and take out, prepare standard samples according to GB / T2048, and test the limiting oxygen index of the examples and comparative examples. The results are shown in Table 3.

[0078] Table 3

[0079] Limiting oxygen index (%) Limiting oxygen index (%) Example 1 29.89 Comparative Example 1 29.71 Example 2 30.04 Comparative Example 2 23.68 Example 3 29.95 Comparative Example 3 29.47 Comparative Example 4 29.62 Comparative Example 5 29.38

[0080] From the experimental data of examples 1-3 and comparative examples 1-5 in table 3, it can be found that the graphene-based anticorrosive coating prepared by the present application has good flame retardant performance.

[0081] By comparison, the limiting oxygen index of examples 1-3 is greater than that of comparative example 2, which indicates that the functional siloxane oligomer is prepared by reacting dimethyldimethoxysilane, functional dimethoxysiloxane and 3-aminopropyl dimethoxymethyl silane; the amino group is introduced on the side chain of the functional siloxane oligomer, the amino group introduced on the functional siloxane oligomer can react with the epoxy group, so it can participate in the curing process of the coating, the Si-O-Si bond is introduced in the coating, and the flame retardant performance of the graphene-based anticorrosive coating is improved.

[0082] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application, and it should be understood that the above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application, and any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method of preparing a graphene-based anticorrosive coating, characterized by, The preparation method of the graphene-based anticorrosive coating comprises the following preparation steps: (1) uniformly mix dimethyl dimethoxysilane, functionalized dimethoxysiloxane and 3-aminopropyl dimethoxymethyl silane according to a molar ratio of 1:(0.5-0.6):(0.3-0.4), then add 0.03-0.05 times the mass of dimethyl dimethoxysilane of barium hydroxide, and stir at 200-300 r / min at 78-82 DEG C for 5-6 h under nitrogen protection, and dry at 56-60 DEG C for 4-6 h under vacuum to obtain a functionalized siloxane oligomer; (2) uniformly mix castor oil, epichlorohydrin and toluene, stir at 200-300 r / min at 30-40 DEG C for 20-30 min, add 0.03-0.05 times the mass of castor oil of triethylamine, heat to 55-65 DEG C, and continue to stir for 3-4 h, wash 3-5 times with an equal volume of toluene and deionized water, take the organic phase, and dry at 50-60 DEG C for 7-8 h under vacuum in a drying box to obtain modified castor oil; (3) uniformly mix pre-modified graphene, sodium lignosulfonate and deionized water, add 2-2.2 times the mass of sodium lignosulfonate of tetraethylenepentamine, add 0.8-1 times the mass of sodium lignosulfonate of formaldehyde aqueous solution, and stir at 200-300 r / min at 88-92 DEG C for 7-8 h, filter, wash 3-5 times with anhydrous ethanol and deionized water, and dry at 60-70 DEG C for 8-9 h under vacuum to obtain modified graphene; (4) according to mass fraction, take 24-26 parts of epoxy resin, 18-20 parts of modified castor oil, 10-12 parts of functionalized siloxane oligomer, 2-3 parts of modified graphene, 6-8 parts of isophorone diamine and 20-22 parts of acetone, uniformly mix the epoxy resin, modified castor oil, functionalized siloxane oligomer, modified graphene, isophorone diamine and acetone to obtain a graphene-based anticorrosive coating; The preparation method of the functionalized dimethoxysiloxane in step (1) is as follows: add 4-amino-2,2,6,6-tetramethylpiperidine-1-oxide to 8-10 times the mass of 3-glycidyl ether oxypropyl dimethoxymethyl silane of tetrahydrofuran according to a molar ratio of 1:1, stir at 200-300 r / min at 58-62 DEG C for 3-4 h, and dry at 58-62 DEG C for 7-8 h under vacuum to obtain the functionalized dimethoxysiloxane. The preparation method of the pre-modified graphene in step (3) is as follows: mixing cerium nitrate, polyvinylpyrrolidone, deionized water and anhydrous ethanol uniformly, stirring at 10-30℃ and 200-300r / min for 50-60min, adding graphene oxide with 4-5 times the mass of cerium nitrate, continuing to stir for 2-3h, placing in a high-pressure reaction kettle, stirring at 118-122℃ and 200-300r / min for 22-24h, filtering, washing with anhydrous ethanol and deionized water for 3-5 times respectively, drying at 70-80℃ under vacuum for 8-9h, and obtaining the pre-modified graphene.

2. The method for preparing a graphene-based anti-corrosion coating according to claim 1, characterized in that, The mass ratio of castor oil, epichlorohydrin and toluene in step (2) is 1:(0.4-0.6):(8-10).

3. The method for preparing a graphene-based anti-corrosion coating according to claim 1, characterized in that... The type of the polyvinylpyrrolidone is PVP-K30.

4. The method for preparing a graphene-based anti-corrosion coating according to claim 1, characterized in that, The mass ratio of cerium nitrate, polyvinylpyrrolidone, deionized water and anhydrous ethanol is 1:(1.2-1.4):(90-100):(260-280).

5. The method for preparing a graphene-based anti-corrosion coating according to claim 1, characterized in that, The mass ratio of the pre-modified graphene, sodium lignosulfonate and deionized water in step (3) is 1:(3-4):(200-220).

6. The method for preparing a graphene-based anti-corrosion coating according to claim 1, characterized in that, The mass fraction of the formaldehyde aqueous solution in step (3) is 37%.

7. The method for preparing a graphene-based anti-corrosion coating according to claim 1, characterized in that, The type of the epoxy resin in step (4) is E51. 8.A graphene-based anticorrosive paint prepared by the preparation method of the graphene-based anticorrosive paint according to any one of claims 1-7.

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