Self-repairing anticorrosive coating and preparation method thereof

Abstract

The application relates to the field of intelligent anticorrosive coatings for metal surfaces, and discloses a self-repairing anticorrosive coating and a preparation method thereof, which comprises the following steps: (1) mixing self-healing microcapsules, rust conversion microcapsules and epoxy resin; (2) mixing the material obtained in the step (1), an adhesion promoter, a toughening agent, a leveling agent and an anti-settling agent, and then standing to obtain an epoxy resin mixture; (3) mixing the epoxy resin mixture and a curing agent, and then standing to obtain the self-repairing anticorrosive coating; wherein the core of the self-healing microcapsule is graphene oxide modified isocyanate; the core of the rust conversion microcapsule is a composite rust conversion agent; and the composite rust conversion agent is obtained by compounding a penetrating rust conversion agent and a stable rust conversion agent. The self-repairing anticorrosive coating can repair the coating body and the base metal, is beneficial to improving the protection effect and service life of the coating, and has better healing effect and corrosion resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of intelligent anticorrosive coatings for metal surfaces, and in particular to a self-repairing anticorrosive coating and a preparation method thereof. BACKGROUND

[0002] Coating protection technology is an important means to delay the corrosion problem of petroleum refining production and storage and transportation devices. The dense coating covering the surface of the equipment can effectively prevent the direct contact of corrosive medium and the base metal, and produce good barrier shielding effect. Compared with new alloy technology, electrochemical protection method, and inhibitor injection method, coating protection technology has the advantages of high corrosion resistance, convenient coating, and low cost.

[0003] However, defects (bubbles, pores, stress concentration, scratch damage, etc.) inevitably exist in the coating, which mainly come from the preparation and actual service process. In order to reduce the potential risk hidden danger brought by the defects to the material, it is usually necessary to take regular maintenance, surface repair and other ways for secondary treatment of the coating, which not only leads to the increase of cost, environmental pollution and waste of materials, but also the repair effect of the coating is difficult to meet the original performance requirements. Today, the coating self-repairing technology referring to the principle of bionics has become a focus in the field of material corrosion and protection, and is expected to become an effective way to solve the defect problem of polymer resin coating. Among them, the microcapsule external aid type self-repairing coating can actively respond to the stimulus of external damage, release the repair material through the capsule core seepage in the local area and form a healing protective layer, and has the characteristics of strong universal applicability and easy operation, and is mainly applied to special coatings used in some high-precision industries in complex and harsh environments which are difficult to maintain.

[0004] At present, researchers have proposed many microcapsule preparation methods for damage healing and their application cases in self-repairing coatings. For example, patent CN 111087845B discloses a microcapsule composed of a polyurethane capsule wall and natural plant oil, which can repair the coating at the defect position according to the change of pH when it is used as a filler and mixed into the coating; patent CN 102728288B discloses a self-repairing microcapsule with a capsule wall of plasma surface modified carbon material modified urea-formaldehyde resin and a capsule core of isocyanate derivative, which improves the toughness and anti-stirring ability of the microcapsule.

[0005] However, the related research still has the following problems: (1) the healing substance formed at the damage position of the microcapsule type self-repairing coating has poor barrier performance itself, which weakens the corrosion resistance and service life of the repaired coating; (2) the healing period of the coating defect is long, and during this period, local corrosion may occur at the exposed metal at the damaged position, and the loose rust at this position will cause the adhesion between the healing substance and the substrate to decrease, resulting in peeling and metal re-rusting during service. SUMMARY

[0006] The present application aims to overcome the problems of insufficient corrosion resistance after self-healing of the coating and the phenomenon of re-rust of the base metal at the damage site affecting the adhesion of the coating in the existing self-repairing anticorrosive coating, and provides a self-repairing anticorrosive coating and a preparation method thereof, which can perform dual repair on the coating body and the base metal and has better healing effect and corrosion resistance.

[0007] To achieve the above-mentioned purpose, the present application provides a preparation method of a self-repairing anticorrosive coating, which comprises the following steps:

[0008] (1) mixing self-healing microcapsules, rust conversion microcapsules and epoxy resin;

[0009] (2) mixing the material obtained in step (1), an adhesion promoter, a toughening agent, a leveling agent and an anti-settling agent and then standing to obtain an epoxy resin mixture;

[0010] (3) mixing the epoxy resin mixture and a curing agent and then standing to obtain a self-repairing anticorrosive coating;

[0011] Preferably, the weight ratio of the self-healing microcapsules, the rust conversion microcapsules, the epoxy resin, the curing agent, the adhesion promoter, the toughening agent, the leveling agent and the anti-settling agent is 6-13:5-11:50:20-30:0.5-1.5:4-8:0.5-1.5:0.1-0.8.

[0012] Preferably, in step (1), the mixing conditions include mixing at a stirring speed of 400-600 r / min for 30-60 min.

[0013] Preferably, in step (2), the mixing conditions include mixing at a stirring speed of 800-1200 r / min for 30-60 min.

[0014] Preferably, in step (2), the standing time is 48-72 h.

[0015] Preferably, in step (3), the mixing conditions include mixing at a stirring speed of 600-1000 r / min for 30-50 min.

[0016] Preferably, in step (3), the standing time is 48-72 h.

[0017] Preferably, in step (3), the mixing conditions include mixing at a stirring speed of 600-1000 r / min for 30-50 min.

[0018] Preferably, in step (3), the standing time is 48-72 h.

[0019] Preferably, the standing time in step (3) is 4-8h.

[0020] Preferably, the epoxy resin is selected from one or two or more of bisphenol A type epoxy resin E-33, bisphenol A type epoxy resin E-35, bisphenol A type epoxy resin E-42, bisphenol A type epoxy resin E-44, bisphenol A type epoxy resin E-51, bisphenol A type epoxy resin E-55, bisphenol F type epoxy resin DER-351, bisphenol F type epoxy resin DER-352, bisphenol F type epoxy resin DER-356, glycidyl ester type epoxy resin, phenolic epoxy resin EPN-1138, phenolic epoxy resin EPN-1179, phenolic epoxy resin EPN-1183, phenolic epoxy resin DEN-431 and phenolic epoxy resin DEN-438.

[0021] Preferably, the adhesion promoter is selected from one or two or more of BYK-4509, BYK-4510, BYK-4511 and BYK-4512.

[0022] Preferably, the toughening agent is selected from one or two or more of F-100, F-201 and F-202.

[0023] Preferably, the leveling agent is selected from one or two or more of BYK-397, ECO-3758 and ECO-3880.

[0024] Preferably, the anti-settling agent is selected from one or two or more of fumed silica UG-SP15G, fumed silica R972, fumed silica HT-822 and fumed silica HT-900.

[0025] Preferably, the curing agent is selected from one or two or more of diethylene triamine, triethylene tetramine, N,N-dimethylaminopropylamine, 3-diethylaminopropylamine and hydroxyethyl ethylenediamine.

[0026] Preferably, the preparation method of the self-healing microcapsule comprises:

[0027] S1: mixing graphene oxide and isocyanate in a weight ratio of 1:49-99, and then performing ultrasonic dispersion to obtain graphene oxide modified isocyanate capsule core;

[0028] S2: mixing urea, resorcinol, ammonium chloride, water, emulsifier A solution, co-emulsifier A and graphene oxide modified isocyanate capsule core;

[0029] S3: adjusting the pH value of the emulsion obtained in step S2 to 3-4, then adding dropwise a formaldehyde solution, then performing ultrasonic dispersion, and finally performing reaction under stirring conditions;

[0030] S4: washing and vacuum drying the material obtained in step S3.

[0031] Preferably, in step S1, the number of layers of the graphene oxide is 1-20 layers, and the size of the microsheet is 5-25 μm.

[0032] Preferably, the isocyanate is selected from one or two or more of hexamethylene diisocyanate, hexamethylene diisocyanate trimer, isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, L-lysine diisocyanate, norbornane dimethylene isocyanate, xylylene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate.

[0033] Preferably, in step S1, the time of ultrasonic dispersion is 10-20 min.

[0034] Preferably, the weight ratio of the urea, the resorcinol, the ammonium chloride, the water, the emulsifier A solution, the co-emulsifier A, the graphene oxide modified isocyanate capsule core, and the formaldehyde solution is 4-8: 1: 0.5-2: 150-400: 10-25: 1-4: 7-24: 8-30.

[0035] Preferably, the concentration of the emulsifier A solution is 2-5 wt%.

[0036] Preferably, the emulsifier A is selected from sodium dodecyl benzene sulfonate and / or sodium dodecyl sulfate.

[0037] Preferably, the co-emulsifier A is selected from one or two or more of n-butanol, propylene glycol, and glycerol.

[0038] Preferably, the concentration of the formaldehyde solution is 35-40 wt%.

[0039] Preferably, the process of step S2 comprises: mixing the urea, the resorcinol, the ammonium chloride, and the water to obtain a mixed solution; then mixing the mixed solution, the emulsifier A solution, and the co-emulsifier A under stirring for 30-60 min, and then adding the graphene oxide modified isocyanate capsule core dropwise, and continuing to mix for 45-60 min after the graphene oxide modified isocyanate capsule core is added dropwise.

[0040] Preferably, the stirring speed is 400-600 r / min.

[0041] Preferably, in step S3, the ultrasonic dispersion conditions comprise: a temperature of 0-5 ℃, a time of 15-40 min, and an ultrasonic power of 20-35 kHz.

[0042] Preferably, the stirring speed in step S3 is 650-900 r / min.

[0043] Preferably, the reaction conditions include: increasing the temperature to 50-70℃ at a temperature increasing speed of 0.5-2℃ / min for 3-5 h.

[0044] Preferably, the method for preparing the rust conversion microcapsule comprises:

[0045] (a) dispersively grinding the penetrating rust conversion agent and the stable rust conversion agent at a weight ratio of 5-9:1 to obtain a composite rust conversion agent core;

[0046] (b) mixing urea, resorcinol, ammonium chloride, water, an emulsifier B solution, a co-emulsifier B, and the composite rust conversion agent core;

[0047] (c) adjusting the pH value of the emulsion obtained in step (b) to 3-4, then adding dropwise a formaldehyde solution, followed by ultrasonic dispersion, and finally reacting under stirring;

[0048] (d) washing and vacuum drying the material obtained in step (c).

[0049] Preferably, in step (a), the penetrating rust conversion agent is selected from one or more than two of linseed oil, dehydrated rust-proof oil, oxidized fish oil, and rust-proof paraffin oil.

[0050] Preferably, the stable rust conversion agent is selected from one or more than two of aluminum tripolyphosphate, aluminum dihydrogen tripolyphosphate, zinc phosphate, zinc oxide, and zinc chromate.

[0051] Preferably, in step (a), the dispersively grinding conditions include dispersively grinding at a rotation speed of 2000-4000 r / min for 30-60 min.

[0052] Preferably, the weight ratio of the urea, resorcinol, ammonium chloride, water, emulsifier B solution, co-emulsifier B, composite rust conversion agent core, and formaldehyde solution is 4-8:1:0.5-2:150-400:15-40:1-4:6-15:8-30.

[0053] Preferably, the concentration of the emulsifier B solution is 2-5 wt%.

[0054] Preferably, the emulsifier B is selected from sodium dodecyl benzene sulfonate and / or sodium dodecyl sulfate.

[0055] Preferably, the co-emulsifier B is selected from one or more than two of n-butanol, propylene glycol, and glycerol.

[0056] Preferably, the concentration of the formaldehyde solution is 35-40wt%.

[0057] Preferably, the process of step (b) comprises: mixing urea, resorcinol, ammonium chloride and water to obtain a mixed solution; then mixing the mixed solution, the emulsifier B solution and the co-emulsifier B under stirring for 30-60min, followed by dropwise adding the composite rust conversion agent capsule core, and continuing to mix for 45-60min after the dropwise adding of the composite rust conversion agent capsule core is completed.

[0058] Preferably, the stirring speed is 400-600r / min.

[0059] Preferably, in step (c), the ultrasonic dispersion conditions comprise: a temperature of 0-5℃, a time of 15-40min, and an ultrasonic power of 20-35kHz.

[0060] Preferably, in step (c), the stirring speed is 1000-2000r / min.

[0061] Preferably, the reaction conditions comprise: increasing the temperature to 50-70℃ at a temperature increasing speed of 0.5-2℃ / min and reacting for 3-5h.

[0062] The second aspect of the present application provides a self-repairing anticorrosive coating obtained by the above-mentioned method for preparing the self-repairing anticorrosive coating.

[0063] The self-repairing anticorrosive coating obtained by the present application can repair the coating body and the base metal, which is beneficial to improve the protective effect and service life of the coating, increase the reliability of the self-repairing coating, and has better healing effect and corrosion resistance. BRIEF DESCRIPTION OF DRAWINGS

[0064] Figure 1 is a scanning electron microscope image of the self-healing microcapsule prepared in Example 1;

[0065] Figure 2 is a scanning electron microscope image of the rust conversion microcapsule prepared in Example 2;

[0066] Figure 3 is a scanning electron microscope image of the rust conversion microcapsule prepared in Example 2 after being crushed by extrusion;

[0067] Figure 4 is an infrared spectrum of the self-healing microcapsule prepared in Example 3 and after being crushed by extrusion;

[0068] Figure 5 is an electrochemical impedance spectrum Nyquist diagram of the test example 3 after scratch immersion corrosion for 480h;

[0069] Figure 6is a schematic diagram of the corrosion resistance mechanism when the scratch immersion corrosion of Test Example 3 is 480h;

[0070] Figure 7 is an optical micro-morphology when the scratch immersion corrosion of Test Example 5 is 480h. DETAILED DESCRIPTION

[0071] The specific embodiments of the present application are described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and explanatory in nature and are not intended to limit the application.

[0072] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and any values are understood to be approximate values. The exact values are understood to be within the range of values. Any numerical value, however, can be expressed as approximately or approximately.

[0073] The first aspect of the present application provides a preparation method of a self-repairing anticorrosive coating, the preparation method comprising the following steps:

[0074] (1) mixing self-healing microcapsules, rust conversion microcapsules and epoxy resin;

[0075] (2) mixing the material obtained in step (1), adhesion promoter, toughening agent, leveling agent and anti-settling agent, and then standing to obtain an epoxy resin mixture;

[0076] (3) mixing the epoxy resin mixture and the curing agent, and then standing to obtain a self-repairing anticorrosive coating;

[0077] The core of the self-healing microcapsule is graphene oxide modified isocyanate;

[0078] The core of the rust conversion microcapsule is a composite rust conversion agent;

[0079] The composite rust conversion agent is obtained by compounding a penetration type rust conversion agent and a stable type rust conversion agent.

[0080] In a preferred case, the weight ratio of the self-healing microcapsules, the rust conversion microcapsules, the epoxy resin, the curing agent, the adhesion promoter, the toughening agent, the leveling agent and the anti-settling agent is 6-13:5-11:50:20-30:0.5-1.5:4-8:0.5-1.5:0.1-0.8.

[0081] In a preferred embodiment, in step (1), the mixing condition comprises mixing at a stirring speed of 400-600 r / min for 30-60 min, and more preferably, the mixing condition comprises mixing at a stirring speed of 450-600 r / min for 30-50 min. Specifically, the stirring speed can be 450 r / min, 500 r / min, 550 r / min or 600 r / min, and the mixing time can be 30 min, 35 min, 40 min, 45 min or 50 min.

[0082] In a preferred embodiment, in step (2), the mixing condition comprises mixing at a stirring speed of 800-1200 r / min for 30-60 min, and more preferably, the mixing condition comprises mixing at a stirring speed of 800-1000 r / min for 40-60 min. In a specific embodiment, the stirring speed can be 800 r / min, 850 r / min, 900 r / min, 950 r / min or 1000 r / min, and the mixing time can be 40 min, 45 min, 50 min, 55 min or 60 min.

[0083] In step (2) of the present application, the purpose of standing is to defoam, and by controlling the standing time, a better defoaming effect can be achieved. Therefore, in a preferred embodiment, in step (2), the standing time is 48-72 h. In a specific embodiment, the standing time can be 48 h, 52 h, 56 h, 60 h, 64 h, 68 h or 72 h.

[0084] In a preferred embodiment, in step (3), the mixing condition comprises mixing at a stirring speed of 600-1000 r / min for 30-50 min, and more preferably, the mixing condition comprises mixing at a stirring speed of 600-800 r / min for 35-45 min. In a specific embodiment, the stirring speed can be 600 r / min, 650 r / min, 700 r / min, 750 r / min or 800 r / min, and the mixing time can be 35 min, 37 min, 39 min, 41 min, 43 min or 45 min.

[0085] In step (3) of the present application, again the purpose of standing is to defoam, and by controlling the standing time, a better defoaming effect can be achieved. Therefore, in a preferred embodiment, in step (3), the standing time is 4-8 h. Specifically, the standing time can be 4 h, 5 h, 6 h, 7 h or 8 h.

[0086] In a preferred embodiment, the epoxy resin in step (1) of the present application is selected from one or more of bisphenol A type epoxy resin E-33, bisphenol A type epoxy resin E-35, bisphenol A type epoxy resin E-42, bisphenol A type epoxy resin E-44, bisphenol A type epoxy resin E-51, bisphenol A type epoxy resin E-55, bisphenol F type epoxy resin DER-351, bisphenol F type epoxy resin DER-352, bisphenol F type epoxy resin DER-356, glycidyl ester type epoxy resin, phenolic epoxy resin EPN-1138, phenolic epoxy resin EPN-1179, phenolic epoxy resin EPN-1183, phenolic epoxy resin DEN-431, and phenolic epoxy resin DEN-438.

[0087] In a preferred embodiment, the adhesion promoter in step (2) of the present application is selected from one or more of BYK-4509, BYK-4510, BYK-4511, and BYK-4512.

[0088] In a preferred embodiment, the toughening agent in step (2) of the present application is selected from one or more of F-100, F-201, and F-202.

[0089] In a preferred embodiment, the leveling agent in step (2) of the present application is selected from one or more of BYK-397, ECO-3758, and ECO-3880.

[0090] In a preferred embodiment, the anti-settling agent in step (2) of the present application is selected from one or more of fumed silica UG-SP15G, fumed silica R972, fumed silica HT-822, and fumed silica HT-900.

[0091] In a preferred embodiment, the curing agent in step (3) of the present application is selected from one or more of diethylene triamine, triethylene tetramine, N,N-dimethyl aminopropylamine, 3-diethyl aminopropylamine, and hydroxyethyl ethylenediamine.

[0092] In the present application, the self-healing microcapsule is synthesized by interfacial polymerization, and comprises a capsule wall and a capsule core, which are urea-formaldehyde resin and graphene oxide modified isocyanate, respectively. The preparation method of the self-healing microcapsule comprises:

[0093] S1: mixing graphene oxide and isocyanate in a weight ratio of 1:49-99, and then performing ultrasonic dispersion to obtain graphene oxide modified isocyanate capsule core;

[0094] S2: mixing urea, resorcinol, ammonium chloride, water, emulsifier A solution, co-emulsifier A, and graphene oxide modified isocyanate capsule core;

[0095] S3: adjusting the pH value of the emulsion obtained in step S2 to 3-4, then adding a formaldehyde solution, followed by ultrasonic dispersion, and finally reacting under stirring;

[0096] S4: washing and vacuum drying the material obtained in step S3.

[0097] In step S1 of the present application, the number of layers of the graphene oxide is 1-20 layers, and the size of the microsheet is 5-25 μm. The graphene oxide can be prepared by the Hummers method, the improved Hummers method, the Brodie method, the Staudenmaier method, or can be directly used as a commercially available product.

[0098] The graphene oxide in the present application has excellent barrier properties of the sheet layer, and its surface is grafted with abundant oxygen-containing functional groups, which can be uniformly dispersed in isocyanate. The use of graphene oxide to modify the isocyanate repair agent can improve the barrier ability of the damaged position of the coating after repair and the overall durability of the coating.

[0099] In a preferred case, in step S1, the isocyanate is selected from one or two or more of hexamethylene diisocyanate, hexamethylene diisocyanate trimer, isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, L-lysine diisocyanate, norbornane dimethylene isocyanate, xylylene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate.

[0100] In a specific embodiment of the present application, in step S1, the weight ratio of graphene oxide to isocyanate can be 1:49, 1:59, 1:69, 1:79, 1:89, or 1:99.

[0101] Preferably, in step S1, the ultrasonic dispersion time is 10-20 min, and further preferably 15-20 min. In a specific embodiment, the ultrasonic dispersion time can be 15 min, 16 min, 17 min, 18 min, 19 min, or 20 min.

[0102] Preferably, the weight ratio of the urea, resorcinol, ammonium chloride, water, emulsifier A solution, co-emulsifier A, graphene oxide modified isocyanate core, and formaldehyde solution is 4-8:1:0.5-2:150-400:10-25:1-4:7-24:8-30.

[0103] In step S2 of the present application, if the emulsifier A raw material is directly added, a large number of bubbles are easily generated during the addition process, which is not conducive to the stability of the system. Therefore, the emulsifier A is first prepared into an emulsifier A solution with a certain concentration, and then added, thereby avoiding the generation of a large number of bubbles.

[0104] Therefore, in the preferred case, the concentration of the emulsifier A solution in step S2 is 2-5wt%. Specifically, it can be 2wt%, 3wt%, 4wt% or 5wt%.

[0105] Preferably, in step S2, the emulsifier A is selected from sodium dodecyl benzene sulfonate and / or sodium dodecyl sulfate.

[0106] Preferably, in step S2, the co-emulsifier A is selected from one or more than two of n-butanol, propylene glycol and glycerol.

[0107] Preferably, the process of step S2 comprises: mixing urea, resorcinol, ammonium chloride and water to obtain a mixed solution; then mixing the mixed solution, the emulsifier A solution and the co-emulsifier A under stirring for 30-60min, followed by dropwise adding the graphene oxide modified isocyanate capsule core, and continuing to mix for 45-60min after the dropwise adding of the graphene oxide modified isocyanate capsule core is completed.

[0108] Further preferably, in step S2, the mixed solution, the emulsifier A solution and the co-emulsifier A are mixed under stirring for 45-55min, followed by dropwise adding the graphene oxide modified isocyanate capsule core, and continuing to mix for 45-50min after the dropwise adding of the graphene oxide modified isocyanate capsule core is completed.

[0109] In a specific embodiment, in step S2, the mixed solution, the emulsifier A solution and the co-emulsifier A are mixed for a time of 45min, 46min, 47min, 48min, 49min, 50min, 51min, 52min, 53min, 54min or 55min, and the graphene oxide modified isocyanate capsule core is continued to be mixed for a time of 45min, 46min, 47min, 48min, 49min or 50min after the dropwise adding of the graphene oxide modified isocyanate capsule core is completed.

[0110] In step S2, in order to keep the mixed system uniform and stable and prevent demulsification caused by change of rotation speed, the stirring speed is controlled to be the same during the mixing of the mixed solution, the emulsifier A solution and the co-emulsifier A, the dropwise adding of the graphene oxide modified isocyanate capsule core and the continued mixing after the dropwise adding is completed.

[0111] In step S2, in order to make the graphene oxide modified isocyanate capsule core mix more uniformly and at the same time avoid polymerization reaction of the graphene oxide modified isocyanate capsule core with water during rapid addition, preferably, the dropwise adding time of the graphene oxide modified isocyanate capsule core is controlled to be 0.5-1h, and the dropwise adding speed is uniform.

[0112] Preferably, in step S2, the stirring speed is 400-600 r / min, further preferably 500-600 r / min. Specifically, the stirring speed can be 500 r / min, 525 r / min, 550 r / min or 600 r / min.

[0113] In step S3 of the present application, the pH value of the emulsion obtained in step S2 can be adjusted to 3, 3.1, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9 or 4.

[0114] In step S3 of the present application, the pH value of the emulsion obtained in step S2 can be adjusted using a pH adjusting agent commonly used in the art, which is not particularly limited as long as it can adjust the pH value of the emulsion obtained in step S2 to 3-4.

[0115] In step S3 of the present application, in order to achieve better results, after adjusting the pH value of the emulsion obtained in step S2 to 3-4, an antifoaming agent can be added to eliminate bubbles in the system, and then the formaldehyde solution is added dropwise.

[0116] The selection and amount of the antifoaming agent are not particularly limited as long as it can eliminate bubbles in the system.

[0117] Preferably, in step S3, the concentration of the formaldehyde solution is 35-40 wt%. Specifically, it can be 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt% or 40 wt%.

[0118] In step S3 of the present application, in order to avoid rapid polymerization of the capsule wall caused by the addition of the formaldehyde solution in a short time, and to obtain self-healing microcapsules with good core coating, the dropwise addition time of the formaldehyde solution is controlled to be 0.5-1 h, and the dropwise addition speed is uniform.

[0119] Preferably, in step S3, the ultrasonic dispersion conditions include a temperature of 0-5℃, a time of 15-40 min, and an ultrasonic power of 20-35 kHz. Specifically, the ultrasonic dispersion temperature can be 0℃, 1℃, 2℃, 3℃, 4℃ or 5℃, the ultrasonic dispersion time can be 15 min, 20 min, 25 min, 30 min, 35 min or 40 min, and the ultrasonic power can be 20 kHz, 25 kHz, 30 kHz or 35 kHz.

[0120] Preferably, in step S3, the stirring speed is 650-900 r / min, further preferably 700-800 r / min. Specifically, the stirring speed can be 700 r / min, 725 r / min, 750 r / min or 800 r / min.

[0121] Preferably, in step S3, the reaction conditions include: warming up to 50-70℃ at a warming rate of 0.5-2℃ / min for 3-5h.

[0122] In step S4 of the present application, the specific operation of the washing includes: mixing the material obtained in step S3 with ethanol, then performing suction filtration, and then washing the solid obtained by suction filtration with petroleum ether.

[0123] In step S4, the purpose of using ethanol and petroleum ether is that the self-healing microcapsules obtained in step S3 may be mutually adhered, and the use of ethanol and petroleum ether can improve the dispersibility of the microcapsules in the system, facilitating the subsequent obtaining of microcapsule powder.

[0124] In the present application, the rust conversion microcapsules are prepared by an interfacial polymerization method, and the rust conversion microcapsules include a capsule wall and a capsule core, and the capsule wall and the capsule core are urea-formaldehyde resin and a composite rust conversion agent, respectively. The preparation method of the rust conversion microcapsules includes:

[0125] (a) dispersing and grinding a penetrating rust conversion agent and a stable rust conversion agent at a weight ratio of 5-9:1 to obtain a composite rust conversion agent capsule core;

[0126] (b) mixing urea, resorcinol, ammonium chloride, water, a solution of emulsifier B, a co-emulsifier B, and the composite rust conversion agent capsule core;

[0127] (c) adjusting the pH value of the emulsion obtained in step (b) to 3-4, then adding a formaldehyde solution dropwise, then performing ultrasonic dispersion, and finally performing a reaction under stirring;

[0128] (d) washing and vacuum drying the material obtained in step (c).

[0129] Preferably, in step (a), the penetrating rust conversion agent is selected from one or more than two of linseed oil, dehydrated rust-proof oil, oxidized fish oil, and rust-proof paraffin oil.

[0130] Preferably, in step (a), the stable rust conversion agent is selected from one or more than two of aluminum tripolyphosphate, aluminum dihydrogen tripolyphosphate, zinc phosphate, zinc oxide, and zinc chromate.

[0131] In a preferred case, in step (a), the weight ratio of the penetrating rust conversion agent to the stable rust conversion agent is 6-8:1. Specifically, it can be 6:1, 7:1, or 8:1.

[0132] The composite rust conversion agent in the application has the advantages of both penetrating rust conversion agent and stable conversion agent, can quickly penetrate into the interior of metal rust, convert it into a dense inert iron-based heteropoly acid complex protective layer, produce strong adhesion effect, prevent the spread of local corrosion, and further enhance the corrosion resistance and substrate adhesion of the repaired coating.

[0133] Preferably, in step (a), the dispersion grinding conditions include: dispersion grinding at a speed of 2000-4000 r / min for 30-60 min, and further preferably, the dispersion grinding conditions include: dispersion grinding at a speed of 2000-3300 r / min for 45-60 min. Specifically, the speed can be 2000 r / min, 2200 r / min, 2400 r / min, 2600 r / min, 2800 r / min, 3000 r / min, 3200 r / min or 3300 r / min, and the time can be 45 min, 48 min, 51 min, 54 min, 57 min or 60 min.

[0134] Preferably, the weight ratio of the urea, resorcinol, ammonium chloride, water, emulsifier B solution, co-emulsifier B, composite rust conversion agent core and formaldehyde solution is 4-8:1:0.5-2:150-400:15-40:1-4:6-15:8-30.

[0135] Also in step (b) of the application, if the emulsifier B raw material is directly added, a large amount of bubbles is easily generated during the addition process, which is not conducive to the stability of the system, therefore, the emulsifier B is first prepared into an emulsifier B solution with a certain concentration, and then added, to avoid the generation of a large amount of bubbles.

[0136] Therefore, in the preferred case, in step (b), the concentration of the emulsifier B solution is 2-5 wt%. Specifically, it can be 2 wt%, 3 wt%, 4 wt% or 5 wt%.

[0137] Preferably, in step (b), the emulsifier B is selected from sodium dodecyl benzene sulfonate and / or sodium dodecyl sulfate.

[0138] Preferably, in step (b), the co-emulsifier B is selected from one or more than two of n-butanol, propylene glycol and glycerol.

[0139] Preferably, the process of step (b) includes: mixing urea, resorcinol, ammonium chloride and water to obtain a mixed solution; then mixing the mixed solution, the emulsifier B solution and the co-emulsifier B under stirring for 30-60 min, and then adding the composite rust conversion agent core dropwise, and continuing to mix for 45-60 min after the addition of the composite rust conversion agent core is completed.

[0140] Further preferably, in step (b), the mixed solution, the emulsifier B solution and the co-emulsifier B are mixed for 45-60 min under stirring. Specifically, the mixing time can be 45 min, 48 min, 51 min, 54 min, 57 min or 60 min.

[0141] In a specific embodiment, in step (b), after the completion of the dropping of the composite rust conversion agent capsule core, the mixing time can be 45 min, 48 min, 51 min, 54 min, 57 min or 60 min.

[0142] In step (b), in order to maintain the uniformity and stability of the mixed system and prevent demulsification caused by the change of the rotating speed, the stirring speed is controlled to be the same during the mixing of the mixed solution, the emulsifier B solution and the co-emulsifier B, the dropping of the composite rust conversion agent capsule core and the continued mixing after the completion of the dropping.

[0143] In step (b), in order to make the composite rust conversion agent capsule core mix more uniformly, in a preferred case, the dropping time of the composite rust conversion agent capsule core is controlled to be 0.5-1 h and the dropping speed is uniform.

[0144] Preferably, in step (b), the stirring speed is 400-600 r / min. Further preferably, the stirring speed is 550-600 r / min. Specifically, the stirring speed can be 550 r / min, 560 r / min, 570 r / min, 580 r / min, 590 r / min or 600 r / min.

[0145] In step (c) of the present application, the pH value of the emulsion obtained in step (b) can be adjusted to 3, 3.1, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9 or 4.

[0146] In step (c) of the present application, the pH value of the emulsion obtained in step (b) can be adjusted by using a pH adjusting agent commonly used in the art, and there is no special requirement for the pH adjusting agent as long as it can adjust the pH value of the emulsion obtained in step (b) to 3-4.

[0147] In step (c) of the present application, in order to achieve better results, after the pH value of the emulsion obtained in step (b) is adjusted to 3-4, an antifoaming agent can be added to eliminate the bubbles in the system, and then the formaldehyde solution is added dropwise.

[0148] There is no special requirement for the selection and amount of the antifoaming agent as long as it can eliminate the bubbles in the system.

[0149] Preferably, in step (c), the concentration of the formaldehyde solution is 35-40 wt%. Specifically, it can be 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt% or 40 wt%.

[0150] In step (c) of the present application, in order to avoid the rapid polymerization of the capsule wall caused by the addition of the formaldehyde solution in a short time, so as to obtain the tarnish-resistant microcapsules with good core coating, the dropping time of the formaldehyde solution is controlled to be 0.5-1 h, and the dropping speed is uniform.

[0151] Preferably, in step (c), the ultrasonic dispersion conditions include: the temperature is 0-5℃, the time is 15-40 min, and the ultrasonic power is 20-35 kHz. Specifically, the ultrasonic dispersion temperature can be 0℃, 1℃, 2℃, 3℃, 4℃ or 5℃, the ultrasonic dispersion time can be 15 min, 20 min, 25 min, 30 min, 35 min or 40 min, and the ultrasonic power can be 20 kHz, 25 kHz, 30 kHz or 35 kHz.

[0152] Preferably, in step (c), the stirring speed is 1000-2000 r / min, and further preferably 1000-1400 r / min. Specifically, the stirring speed can be 1000 r / min, 1100 r / min, 1200 r / min, 1300 r / min or 1400 r / min.

[0153] Preferably, in step (c), the reaction conditions include: heating to 50-70℃ at a heating rate of 0.5-2℃ / min for 3-5 h.

[0154] In step (d) of the present application, the specific operation of the washing includes: mixing the material obtained in step (c) with ethanol, then performing suction filtration, and then washing the solid obtained by suction filtration with petroleum ether.

[0155] In step (d), ethanol and petroleum ether are used because the material obtained in step (c) may have mutual adhesion phenomenon, and the use of ethanol and petroleum ether can improve the dispersibility of the microcapsules in the system, facilitating the subsequent obtaining of the microcapsule powder.

[0156] The second aspect of the present application provides a self-repairing anticorrosive coating prepared by the above-mentioned method.

[0157] Compared with the prior art, the present application has the following beneficial effects:

[0158] (1) In order to solve the problem of insufficient barrier performance after the damage healing of the self-repairing coating, the self-repairing anticorrosive coating with rust conversion function provided by the application contains self-healing microcapsules with urea-formaldehyde resin capsule walls encapsulating graphene oxide modified isocyanate capsule cores. When the coating is damaged by scratches, stress cracking and the like, the capsule core material released by the broken capsule walls can react with water to generate polyurethane repair products to fill the damaged part, thereby producing a local healing effect. Meanwhile, the uniformly dispersed graphene oxide nanoparticles in the repair products can prolong the penetration path of the corrosion medium, thereby synergistically improving the barrier performance and enhancing the corrosion resistance of the repaired coating.

[0159] (2) The self-repairing anticorrosive coating with rust conversion function provided by the application contains rust conversion microcapsules, and the capsule core of the rust conversion microcapsules is a composite rust conversion agent, which has the advantages of both penetration type rust conversion agents and stable type rust conversion agents. The rust conversion agent can penetrate into the interior of metal rust, isolate the further invasion of water, oxygen and other media, and convert the generated corrosion products into a stable inert adhesion layer, which is conducive to delaying the local corrosion during the in-situ healing process of the coating, and can also improve the bonding force between the healing material and the metal substrate, thereby improving the stability of the repaired coating. The self-repairing anticorrosive coating with rust conversion function can be used as an external anticorrosive coating for steel storage tanks, pipelines and other petroleum refining equipment.

[0160] The self-repairing anticorrosive coating with rust conversion function provided by the application is mainly applied to the external surface protection and safeguard of petroleum refining production and storage and transportation devices. By adding self-healing microcapsules and rust conversion microcapsules to the coating resin matrix, the coating can generate high-barrier healing products and inert protective layers at the damaged position when the coating is damaged by external damage and stress cracking, thereby endowing the coating with the functions of in-situ repair of defects and damage and conversion of base metal rust, achieving double self-repair of the coating resin body and base metal rust, and the repaired coating still has good corrosion resistance. Not only does the self-repairing anticorrosive coating with rust conversion function inhibit and delay the corrosion process of the base metal, but also can effectively repair the coating, thereby effectively prolonging the service life and durability of the repaired coating, improving the reliability and durability of the anticorrosive measures, prolonging the inspection and maintenance period and service life of the equipment, and having strong application prospects.

[0161] The application will be described in detail below through examples, but the protection scope of the application is not limited thereto.

[0162] The room temperature described below refers to 25℃.

[0163] Example 1

[0164] (1) 2 g of graphene oxide (GX-pGO, number of layers of sheet 1-10, size of flake 5-20 μm, Gaoene Technology) was mixed with 98 g of isophorone diisocyanate (Aldrich Reagent) in a beaker container, and then ultrasonic dispersion was performed at room temperature for 15 min using a cell ultrasonic disrupter (JY992-IIN, Ningbo Xinzhij), to obtain a graphene oxide modified isocyanate capsule core;

[0165] (2) 8 g of urea (National Reagent), 1.5 g of resorcinol (National Reagent) and 1.5 g of ammonium chloride (National Reagent) were sequentially mixed and dissolved in 500 g of deionized water in a three-necked flask, to obtain a mixed solution; then the mixed solution, 32 g of a 3 wt% sodium dodecylbenzenesulfonate (Aldrich Reagent) solution and 5 g of n-butanol (National Reagent) were stirred and mixed at a stirring speed of 500 r / min for 45 min, and then 26 g of the graphene oxide modified isocyanate capsule core was added dropwise (the dropwise addition time of the graphene oxide modified isocyanate capsule core was controlled to be 0.5 h, and the dropwise addition speed was uniform); after the graphene oxide modified isocyanate capsule core was added dropwise, stirring and mixing were continued for 45 min;

[0166] (3) The pH value of the emulsion obtained in step (2) was adjusted to 3.5 using a 0.05 mol / L hydrochloric acid (National Reagent) solution, 1 drop of 1-octanol (National Reagent) was added to eliminate bubbles in the system, and then 40 g of a 37 wt% formaldehyde (National Reagent) solution was added dropwise (the dropwise addition time of the formaldehyde solution was controlled to be 1 h, and the dropwise addition speed was uniform); followed by ultrasonic dispersion (temperature 0°C, ultrasonic power 20 kHz, time 30 min), and then transferred to an oil bath pot, and heated to 60°C at a heating rate of 1°C / min under stirring at a stirring speed of 750 r / min, and reacted for 4 h;

[0167] (4) The material obtained in step (3) was mixed with ethanol (National Reagent), and then subjected to suction filtration, followed by washing the solid obtained by suction filtration with petroleum ether (National Reagent, boiling point 90-120°C), and finally vacuum drying, to obtain self-healing microcapsules A1;

[0168] (5) 4 g of zinc phosphate (National Reagent) and 32 g of dehydrated rust preventive oil (FK2020D, Dongguan Hans) were placed in a dispersion mill (SWZX-0.5, Shihai Industry), and dispersed and ground at a rotation speed of 2600 r / min for 60 min, to obtain a composite rust conversion agent capsule core;

[0169] (6) In a three-mouth flask, 8 g of urea, 1.5 g of resorcinol and 1.5 g of ammonium chloride were sequentially mixed and dissolved in 500 g of deionized water to obtain a mixed solution; then the obtained mixed solution, 55 g of a 3 wt% sodium dodecylbenzenesulfonate solution and 6 g of n-butanol were stirred and mixed at a stirring speed of 550 r / min for 45 min, and then 22 g of the composite rust conversion agent capsule core was added dropwise (the dropwise adding time of the composite rust conversion agent capsule core was controlled to be 0.5 h, and the dropwise adding speed was uniform); after the dropwise adding of the composite rust conversion agent capsule core was completed, stirring and mixing was continued for 45 min;

[0170] (7) The pH value of the emulsion obtained in step (6) was adjusted to 3.5 by using a 0.05 mol / L hydrochloric acid solution, 1 drop of 1-octanol was added to eliminate bubbles in the system, and then 40 g of a 37 wt% formaldehyde solution was added dropwise (the dropwise adding time of the formaldehyde solution was controlled to be 1 h, and the dropwise adding speed was uniform); then ultrasonic dispersion was performed (the temperature was 0°C, the ultrasonic power was 20 kHz, and the time was 30 min); then it was transferred to an oil bath pot, and heated to 60°C at a heating speed of 1°C / min under the condition that the stirring speed was 1200 r / min, and reacted for 4.5 h;

[0171] (8) The material obtained in step (7) was mixed with ethanol, and then suction filtration was performed; then the obtained solid was washed with petroleum ether, and finally vacuum drying was performed to prepare rust conversion microcapsule A1;

[0172] (9) 8 g of self-healing microcapsule A1 and 6 g of rust conversion microcapsule A1 were added to 50 g of bisphenol A type epoxy resin E-51 (Nanya), and stirring and mixing were performed at a stirring speed of 450 r / min for 30 min by using a paint stirrer (FML-SY550, Famely Technology);

[0173] (10) 0.5 g of adhesion promoter BYK-4509 (Bik), 5 g of toughening agent F-201 (Dow Chemical), 0.5 g of leveling agent BYK-397 (Bik) and 0.5 g of anti-settling agent fumed silica R972 (Degussa) were sequentially added to the material obtained in step (9), and stirring and mixing were performed at a stirring speed of 800 r / min for 60 min, and then standing for 72 h to defoam, to obtain an epoxy resin mixture;

[0174] (11) The epoxy resin mixture and 26.5 g of curing agent triethylenetetramine (Huntsman) were stirred and mixed at a stirring speed of 650 r / min for 45 min, and then standing for 6 h to obtain self-repairing anticorrosive coating A1.

[0175] Example 2

[0176] (1) 1 g of graphene oxide (GX-pGO, layer number of 1-10, microchip size of 5-20 μm, Gaoene Technology) was mixed with 99 g of toluene diisocyanate (National Reagent) in a beaker container, and then ultrasonic dispersion was performed at room temperature for 20 min using a cell ultrasonic disruptor (JY992-IIN, Ningbo Xinzhi), to obtain an isocyanate capsule core modified with graphene oxide;

[0177] (2) 20 g of urea (National Reagent), 3 g of resorcinol (National Reagent) and 3 g of ammonium chloride (National Reagent) were sequentially mixed and dissolved in 800 g of deionized water in a three-necked flask, to obtain a mixed solution; then, the mixed solution, 56 g of a 3 wt% sodium dodecylbenzenesulfonate (Aidrich Reagent) solution and 5 g of propylene glycol (National Reagent) were stirred and mixed at a stirring speed of 550 r / min for 50 min, and then 40 g of the graphene oxide modified isocyanate capsule core was added dropwise (the dropwise addition time of the graphene oxide modified isocyanate capsule core was controlled to be 1 h, and the dropwise addition speed was uniform); after the dropwise addition of the graphene oxide modified isocyanate capsule core was completed, stirring and mixing were continued for 50 min;

[0178] (3) The pH value of the emulsion obtained in step (2) was adjusted to 3.5 using a 0.05 mol / L hydrochloric acid (National Reagent) solution, 1 drop of 1-octanol (National Reagent) was added to eliminate bubbles in the system, and then 60 g of a 37 wt% formaldehyde (National Reagent) solution was added dropwise (the dropwise addition time of the formaldehyde solution was controlled to be 1 h, and the dropwise addition speed was uniform); followed by ultrasonic dispersion (temperature of 1 ℃, ultrasonic power of 25 kHz, and time of 30 min); then, it was transferred to an oil bath pot, and heated to 60 ℃ at a heating rate of 1 ℃ / min under stirring at a stirring speed of 800 r / min, and reacted for 4.5 h;

[0179] (4) The material obtained in step (3) was mixed with ethanol (National Reagent), and then subjected to suction filtration, followed by washing the obtained solid with petroleum ether (National Reagent, boiling point of 90-120 ℃), and finally vacuum drying, to obtain self-healing microcapsule A2;

[0180] (5) 4 g of zinc phosphate (National Reagent) and 24 g of flaxseed oil (Wengjiang Reagent) were placed in a dispersion grinder (SWZX-0.5, Shihai Industry), and dispersed and ground at a rotation speed of 3000 r / min for 45 min, to obtain a composite rust conversion agent capsule core;

[0181] (6) In a three-mouth flask, 20 g of urea, 3 g of resorcinol and 3 g of ammonium chloride were sequentially mixed and dissolved in 800 g of deionized water to obtain a mixed solution; then the obtained mixed solution, 70 g of a 3 wt% sodium dodecylbenzenesulfonate solution and 6 g of propylene glycol were stirred and mixed at a stirring speed of 600 r / min for 50 min, and then 28 g of the composite rust conversion agent capsule core was added dropwise (the dropwise adding time of the composite rust conversion agent capsule core was controlled to be 0.5 h, and the dropwise adding speed was uniform); after the dropwise adding of the composite rust conversion agent capsule core was completed, stirring and mixing was continued for 50 min;

[0182] (7) The pH value of the emulsion obtained in step (6) was adjusted to 3.5 by using a 0.05 mol / L hydrochloric acid solution, 1 drop of 1-octanol was added to eliminate bubbles in the system, and then 60 g of a 37 wt% formaldehyde solution was added dropwise (the dropwise adding time of the formaldehyde solution was controlled to be 1 h, and the dropwise adding speed was uniform); then ultrasonic dispersion was performed (the temperature was 1 ℃, the ultrasonic power was 25 kHz, and the time was 30 min); then it was transferred to an oil bath pot, and heated to 60 ℃ at a heating speed of 1 ℃ / min under the condition that the stirring speed was 1400 r / min, and reacted for 4.5 h;

[0183] (8) The material obtained in step (7) was mixed with ethanol, then suction filtration was performed, then the solid obtained by suction filtration was washed with petroleum ether, and finally vacuum drying was performed to prepare rust conversion microcapsule A2;

[0184] (9) 6 g of self-healing microcapsule A2 and 5 g of rust conversion microcapsule A2 were added to 50 g of bisphenol A type epoxy resin E-44 (Nanya), and a paint stirrer (FML-SY550, Famly Technology) was used to stir and mix at a stirring speed of 500 r / min for 50 min;

[0185] (10) 0.5 g of adhesion promoter BYK-4511 (BIC), 5 g of toughening agent F-201 (Dow Chemical), 0.5 g of leveling agent ECO-3880 (Aikewo) and 0.5 g of anti-settling agent fumed silica R972 (Degussa) were sequentially added to the material obtained in step (9), and stirring and mixing was performed at a stirring speed of 1000 r / min for 60 min, and then standing for 72 h to defoam, to obtain an epoxy resin mixture;

[0186] (11) The epoxy resin mixture and 20 g of curing agent triethylenetetramine (Huntsman) were stirred and mixed at a stirring speed of 650 r / min for 45 min, and then standing for 6 h to obtain a self-repairing anticorrosive coating A2.

[0187] Example 3

[0188] (1) 2 g of graphene oxide (SE1231, the number of layers of the sheet is 5-15, the size of the flake is 5-10 μm, Changzhou Sixth Element) and 98 g of hexamethylene diisocyanate (National Reagent) were mixed in a beaker container, and then ultrasonic dispersion was performed at room temperature for 20 min by using a cell ultrasonic disrupter (JY992-IIN, Ningbo Xinzhi) to obtain a graphene oxide modified isocyanate capsule core;

[0189] (2) 10 g of urea (National Reagent), 2 g of resorcinol (National Reagent) and 2 g of ammonium chloride (National Reagent) were sequentially mixed and dissolved in 650 g of deionized water in a three-necked flask to obtain a mixed solution; then the mixed solution, 30 g of a 3wt% sodium dodecyl sulfate (Maikelin Reagent) solution and 5 g of n-butanol (National Reagent) were stirred and mixed at a stirring speed of 550 r / min for 45 min, and then 28 g of the graphene oxide modified isocyanate capsule core was added dropwise (the dropwise adding time of the graphene oxide modified isocyanate capsule core was controlled to be 0.5 h, and the dropwise adding speed was uniform), and after the graphene oxide modified isocyanate capsule core was completely added dropwise, stirring and mixing were continued for 45 min;

[0190] (3) The pH value of the emulsion obtained in step (2) was adjusted to 4 by using a 0.05 mol / L hydrochloric acid (National Reagent) solution, 2 drops of 1-octanol (National Reagent) were added to eliminate bubbles in the system, and then 45 g of a 37wt% formaldehyde (National Reagent) solution was added dropwise (the dropwise adding time of the formaldehyde solution was controlled to be 1 h, and the dropwise adding speed was uniform), followed by ultrasonic dispersion (the temperature was 0°C, the ultrasonic power was 30 kHz, and the time was 35 min), and then the system was transferred to an oil bath pot, and was heated to 60°C at a heating speed of 1°C / min under stirring at a stirring speed of 700 r / min, and was reacted for 4 h;

[0191] (4) The material obtained in step (3) was mixed with ethanol (National Reagent), and then was subjected to suction filtration, and then the solid obtained by suction filtration was washed with petroleum ether (National Reagent, the boiling point is 90-120°C), and finally was vacuum dried to obtain self-healing microcapsule A3;

[0192] (5) 6 g of aluminum tripolyphosphate (National Reagent) and 36 g of flaxseed oil (Wengjiang Reagent) were placed in a dispersion grinder (SWZX-0.5, Shihai Industry), and were dispersed and ground at a rotation speed of 3300 r / min for 60 min to obtain a composite rust conversion agent capsule core;

[0193] (6) In a three-neck flask, 10 g of urea, 2 g of resorcinol and 2 g of ammonium chloride were sequentially mixed and dissolved in 650 g of deionized water to obtain a mixed solution; then the obtained mixed solution, 55 g of a 3 wt% sodium dodecyl sulfate solution and 5 g of n-butanol were stirred and mixed at a stirring speed of 550 r / min for 60 min, and then 24 g of the composite rust conversion agent capsule core was added dropwise (the dropwise adding time of the composite rust conversion agent capsule core was controlled to be 0.5 h, and the dropwise adding speed was uniform); after the dropwise adding of the composite rust conversion agent capsule core was completed, stirring and mixing was continued for 60 min;

[0194] (7) The pH value of the emulsion obtained in step (6) was adjusted to 4 by using a 0.05 mol / L hydrochloric acid solution, 2 drops of 1-octanol were added to eliminate bubbles in the system, and then 45 g of a 37 wt% formaldehyde solution was added dropwise (the dropwise adding time of the formaldehyde solution was controlled to be 1 h, and the dropwise adding speed was uniform); then ultrasonic dispersion was performed (the temperature was 0°C, the ultrasonic power was 30 kHz, and the time was 35 min); then it was transferred to an oil bath pot, and heated to 60°C at a heating speed of 1°C / min under the condition that the stirring speed was 1000 r / min, and reacted for 4 h;

[0195] (8) The material obtained in step (7) was mixed with ethanol, then suction filtration was performed, then the obtained solid was washed with petroleum ether, and finally vacuum drying was performed to prepare rust conversion microcapsule A3;

[0196] (9) 7 g of self-healing microcapsule A3 and 10 g of rust conversion microcapsule A3 were added to 50 g of bisphenol F type epoxy resin DER-356 (Dow Chemical), and a paint stirrer (FML-SY550, Famly Technology) was used to stir and mix at a stirring speed of 600 r / min for 50 min;

[0197] (10) 1 g of adhesion promoter BYK-4512 (BYK), 6 g of toughening agent F-100 (Dow Chemical), 1 g of leveling agent ECO-3758 (Aekytech) and 0.5 g of anti-settling agent fumed silica HT-822 (Huating) were sequentially added to the material obtained in step (9), and stirring and mixing was performed at a stirring speed of 800 r / min for 60 min, and then standing for 48 h to defoam, to obtain an epoxy resin mixture;

[0198] (11) The epoxy resin mixture and 20.5 g of curing agent N,N-dimethylaminopropylamine (BASF) were stirred and mixed at a stirring speed of 800 r / min for 45 min, and then standing for 6 h to obtain a self-repairing anticorrosive coating A3.

[0199] Example 4

[0200] (1) 1 g of graphene oxide (SE1231, number of layers of sheet 5-15, size of flake 5-10 μm, Changzhou Sixth Element) was mixed with 79 g of hexamethylene diisocyanate trimer (Aladdin reagent) in a beaker container, and then ultrasonic dispersion was performed at room temperature for 15 min using a cell ultrasonic disrupter (JY992-IIN, Ningbo Xinzhi) to obtain a graphene oxide modified isocyanate capsule core;

[0201] (2) 25 g of urea (National Reagent), 4 g of resorcinol (National Reagent) and 2 g of ammonium chloride (National Reagent) were sequentially mixed and dissolved in 700 g of deionized water in a three-necked flask to obtain a mixed solution; then, the mixed solution, 50 g of a 3 wt% sodium dodecyl sulfate (Macklin reagent) solution and 6 g of glycerol (Aladdin reagent) were stirred and mixed at a stirring speed of 600 r / min for 55 min, and then 28 g of the graphene oxide modified isocyanate capsule core was added dropwise (the dropwise addition time of the graphene oxide modified isocyanate capsule core was controlled to be 0.5 h, and the dropwise addition speed was uniform); after the dropwise addition of the graphene oxide modified isocyanate capsule core was completed, stirring and mixing were continued for 50 min;

[0202] (3) The pH value of the emulsion obtained in step (2) was adjusted to 3.5 using a 0.05 mol / L hydrochloric acid (National Reagent) solution, 2 drops of 1-octanol (National Reagent) were added to eliminate bubbles in the system, and then 38 g of a 37 wt% formaldehyde (National Reagent) solution was added dropwise (the dropwise addition time of the formaldehyde solution was controlled to be 0.5 h, and the dropwise addition speed was uniform); followed by ultrasonic dispersion (temperature 0°C, ultrasonic power 35 kHz, time 30 min), and then transferred to an oil bath pot, and heated to 60°C at a heating rate of 1°C / min under stirring at a stirring speed of 800 r / min for 3.5 h;

[0203] (4) The material obtained in step (3) was mixed with ethanol (National Reagent), and then suction filtration was performed, followed by washing the solid obtained by suction filtration with petroleum ether (National Reagent, boiling point 90-120°C), and finally vacuum drying to prepare self-healing microcapsule A4;

[0204] (5) 6 g of zinc oxide (National Reagent) and 36 g of flaxseed oil (Wengjiang Reagent) were placed in a dispersion mill (SWZX-0.5, Shihai Industry), and dispersed and ground at a rotation speed of 2000 r / min for 60 min to obtain a composite rust conversion agent capsule core;

[0205] (6) In a three-necked flask, 25 g of urea, 4 g of resorcinol and 2 g of ammonium chloride were sequentially mixed and dissolved in 800 g of deionized water to obtain a mixed solution; then the obtained mixed solution, 70 g of a 3 wt% sodium dodecylbenzenesulfonate solution and 5 g of glycerol were stirred and mixed at a stirring speed of 600 r / min for 50 min, and then 30 g of the composite rust conversion agent capsule core was added dropwise (the dropwise adding time of the composite rust conversion agent capsule core was controlled to be 1 h, and the dropwise adding speed was uniform); after the dropwise adding of the composite rust conversion agent capsule core was completed, stirring and mixing was continued for 50 min;

[0206] (7) The pH value of the emulsion obtained in step (6) was adjusted to 3.5 by using a 0.05 mol / L hydrochloric acid solution, 2 drops of 1-octanol were added to eliminate bubbles in the system, and then 38 g of a 37 wt% formaldehyde solution was added dropwise (the dropwise adding time of the formaldehyde solution was controlled to be 0.5 h, and the dropwise adding speed was uniform); then ultrasonic dispersion was performed (the temperature was 0°C, the ultrasonic power was 35 kHz, and the time was 30 min); then it was transferred to an oil bath pot, and heated to 60°C at a heating speed of 1°C / min under the condition that the stirring speed was 1000 r / min, and reacted for 5 h;

[0207] (8) The material obtained in step (7) was mixed with ethanol, then suction filtration was performed, then the solid obtained by suction filtration was washed with petroleum ether, and finally vacuum drying was performed to prepare rust conversion microcapsule A4;

[0208] (9) 13 g of self-healing microcapsule A4 and 9 g of rust conversion microcapsule A4 were added to 50 g of phenolic epoxy resin EPN-1179 (Huntsman), and a paint stirrer (FML-SY550, Famly Technology) was used to stir and mix at a stirring speed of 500 r / min for 50 min;

[0209] (10) 1 g of adhesion promoter BYK-4511 (BYK), 5 g of toughening agent F-201 (Dow Chemical), 1.5 g of leveling agent ECO-3758 (Eccocell) and 0.5 g of anti-settling agent fumed silica R972 (De Gussa) were sequentially added to the material obtained in step (9), and stirring and mixing was performed at a stirring speed of 1000 r / min for 60 min, and then standing for 72 h to defoam, to obtain an epoxy resin mixture;

[0210] (11) The epoxy resin mixture and 30 g of curing agent hydroxyethyl ethylenediamine (BASF) were stirred and mixed at a stirring speed of 600 r / min for 35 min, and then standing for 6 h to obtain a self-repairing anticorrosive coating A4.

[0211] Comparative Example 1

[0212] The method of Example 1 was followed, except that self-healing microcapsule A1 and rust conversion microcapsule A1 were not used, to prepare self-repairing anticorrosive coating D1, and the preparation method was as follows:

[0213] (1) 50 g of bisphenol A type epoxy resin E-51 (Nanya) was stirred at a stirring speed of 450 r / min for 30 min using a paint stirrer (FML-SY550, Famly Technology);

[0214] (2) 0.5 g of adhesion promoter BYK-4509 (BYK), 5 g of toughening agent F-201 (Dow Chemical), 0.5 g of leveling agent BYK-397 (BYK), and 0.5 g of anti-settling agent fumed silica R972 (De Gussa) were sequentially added to the material obtained in step (1), and stirred and mixed at a stirring speed of 800 r / min for 60 min, and then left to stand for 72 h to defoam, to obtain an epoxy resin mixture;

[0215] (3) The epoxy resin mixture and 26.5 g of curing agent triethylenetetramine (Huntsman) were stirred and mixed at a stirring speed of 650 r / min for 45 min, and then left to stand for 6 h, to obtain self-repairing anticorrosive coating D1.

[0216] Comparative Example 2

[0217] The method of Example 1 was followed, except that rust conversion microcapsule A1 was not used, to prepare self-repairing anticorrosive coating D2, and the preparation method was as follows:

[0218] (1) 8 g of self-healing microcapsule A1 was added to 50 g of bisphenol A type epoxy resin E-51 (Nanya), and stirred and mixed at a stirring speed of 450 r / min for 30 min using a paint stirrer (FML-SY550, Famly Technology);

[0219] (2) 0.5 g of adhesion promoter BYK-4509 (BYK), 5 g of toughening agent F-201 (Dow Chemical), 0.5 g of leveling agent BYK-397 (BYK), and 0.5 g of anti-settling agent fumed silica R972 (De Gussa) were sequentially added to the material obtained in step (1), and stirred and mixed at a stirring speed of 800 r / min for 60 min, and then left to stand for 72 h to defoam, to obtain an epoxy resin mixture;

[0220] (3) The epoxy resin mixture and 26.5 g of curing agent triethylenetetramine (Huntsman) were stirred and mixed at a stirring speed of 650 r / min for 45 min, and then left to stand for 6 h, to obtain self-repairing anticorrosive coating D2.

[0221] Comparative Example 3

[0222] The method of Example 1 was followed, except that in step (1), no graphene oxide was added, i.e., the core of the self-healing microcapsules obtained was isophorone diisocyanate, to prepare a self-repairing anticorrosive coating D3, the preparation method being:

[0223] (1) 98 g of isophorone diisocyanate (Aldrin reagent) was placed in a beaker container, and then ultrasonic dispersion was performed at room temperature for 15 min using a cell ultrasonic disruptor (JY992-IIN, Ningbo Xinzhi), to obtain isophorone diisocyanate core;

[0224] (2) 8 g of urea (National Reagent), 1.5 g of resorcinol (National Reagent) and 1.5 g of ammonium chloride (National Reagent) were sequentially mixed and dissolved in 500 g of deionized water in a three-necked flask, to obtain a mixed solution; then the obtained mixed solution, 32 g of a 3 wt% sodium dodecylbenzenesulfonate (Aldrin reagent) solution and 5 g of n-butanol (National Reagent) were stirred and mixed at a stirring speed of 500 r / min for 45 min, and then 26 g of isophorone diisocyanate core was added dropwise (the dropwise addition time of isophorone diisocyanate core was controlled to be 0.5 h, and the dropwise addition speed was uniform); after the dropwise addition of isophorone diisocyanate core was completed, stirring and mixing were continued for 45 min;

[0225] (3) The pH value of the emulsion obtained in step (2) was adjusted to 3.5 using a 0.05 mol / L hydrochloric acid (National Reagent) solution, 1 drop of 1-octanol (National Reagent) was added to eliminate bubbles in the system, and then 40 g of a 37 wt% formaldehyde (National Reagent) solution was added dropwise (the dropwise addition time of the formaldehyde solution was controlled to be 1 h, and the dropwise addition speed was uniform); followed by ultrasonic dispersion (temperature: 0°C, ultrasonic power: 20 kHz, time: 30 min), and then transferred to an oil bath pot, and heated to 60°C at a heating rate of 1°C / min under stirring at a stirring speed of 750 r / min, and reacted for 4 h;

[0226] (4) The material obtained in step (3) was mixed with ethanol (National Reagent), and then subjected to suction filtration, followed by washing the obtained solid with petroleum ether (National Reagent, boiling point: 90-120°C), and finally vacuum drying, to obtain self-healing microcapsules D1;

[0227] (5) 8 g of self-healing microcapsules D1 and 6 g of rust conversion microcapsules A1 were added to 50 g of bisphenol A type epoxy resin E-51 (Nanya), and stirred and mixed at a stirring speed of 450 r / min for 30 min using a paint stirrer (FML-SY550, Famly Technology);

[0228] (6) sequentially adding 0.5 g of adhesion promoter BYK-4509 (BYK), 5 g of toughening agent F-201 (Dow Chemical), 0.5 g of leveling agent BYK-397 (BYK), and 0.5 g of anti-settling agent fumed silica R972 (Degussa) to the material obtained in step (5), stirring and mixing at a stirring speed of 800 r / min for 60 min, and then standing for 72 h to defoam, to obtain an epoxy resin mixture;

[0229] (7) stirring and mixing the epoxy resin mixture and 26.5 g of curing agent triethylenetetramine (Huntsman) at a stirring speed of 650 r / min for 45 min, and then standing for 6 h, to obtain a self-repairing anticorrosive coating D3.

[0230] Comparative Example 4

[0231] The method of Example 1 was followed, except that no zinc phosphate was added, i.e., the core of the rust-converting microcapsules was dehydrated rust-preventive oil, to obtain a self-repairing anticorrosive coating D4, prepared by the following method:

[0232] (1) placing 32 g of dehydrated rust-preventive oil (FK2020D, Dongguan Hans) into a dispersion mill (SWZX-0.5, Shiheng Industry), and dispersing and grinding at a rotation speed of 2600 r / min for 60 min, to obtain a dehydrated rust-preventive oil core;

[0233] (2) sequentially mixing and dissolving 8 g of urea (National Reagent), 1.5 g of resorcinol (National Reagent), and 1.5 g of ammonium chloride (National Reagent) in 500 g of deionized water in a three-necked flask, to obtain a mixed solution; then stirring and mixing the obtained mixed solution, 55 g of a 3 wt% sodium dodecylbenzenesulfonate (Aidrich Reagent) solution, and 6 g of n-butanol (National Reagent) at a stirring speed of 550 r / min for 45 min, and then adding dropwise 22 g of the dehydrated rust-preventive oil core (controlling the dropwise addition time of the dehydrated rust-preventive oil core to be 0.5 h, and the dropwise addition speed to be uniform), and continuing stirring and mixing for 45 min after the dropwise addition of the dehydrated rust-preventive oil core was completed;

[0234] (3) adjusting the pH value of the emulsion obtained in step (2) to 3.5 with 0.05 mol / L hydrochloric acid (National Reagent) solution, adding 1 drop of 1-octanol (National Reagent) to eliminate bubbles in the system, and then adding dropwise 40 g of a 37 wt% formaldehyde (National Reagent) solution (controlling the dropwise addition time of the formaldehyde solution to be 1 h, and the dropwise addition speed to be uniform), followed by ultrasonic dispersion (temperature 0°C, ultrasonic power 20 kHz, time 30 min), and then transferring to an oil bath, and stirring and mixing at a stirring speed of 1200 r / min, and a temperature increasing speed of 1°C / min, to 60°C for 4.5 h;

[0235] (4) The material obtained in step (3) is mixed with ethanol (Guoyao reagent), then filtered, and then the solid obtained by filtration is washed with petroleum ether (Guoyao reagent, boiling point is 90-120℃). Finally, it is vacuum dried to prepare rust-transfer microcapsules D1.

[0236] (5) Add 8g of self-healing microcapsules A1 and 6g of rust-transforming microcapsules D1 to 50g of bisphenol A type epoxy resin E-51 (Nanya), and mix for 30min at a stirring speed of 450r / min using a paint mixer (FML-SY550, Famli Technology).

[0237] (6) Add 0.5g of adhesion promoter BYK-4509 (BYK), 5g of toughening agent F-201 (Dow Chemical), 0.5g of leveling agent BYK-397 (BYK), and 0.5g of anti-settling agent fumed silica R972 (Degussa) to the material obtained in step (5) in sequence. Stir and mix at a stirring speed of 800r / min for 60min, and then let stand for 72h to defoam, to obtain epoxy resin mixture;

[0238] (7) Mix the epoxy resin mixture and 26.5g of curing agent triethylenetetramine (Hunsmann) at a stirring speed of 650r / min for 45min, and then let it stand for 6h to obtain self-healing anti-corrosion coating D4.

[0239] Test Example 1

[0240] The morphology of the self-healing microcapsule A1 from Example 1 and the rust-transforming microcapsule A2 from Example 2, as well as the morphology of the rust-transforming microcapsule A2 after compression and breakage, were observed using a scanning electron microscope (S3400, Hitachi, Japan). The results are shown below. Figures 1-3 As shown;

[0241] according to Figures 1-3 It can be seen that the self-healing microcapsule A1 has a regular spherical structure with a rough and dense surface. According to observation and statistics, the average particle size of the microcapsule is 146 μm.

[0242] The surface of the rust-transforming microcapsules A2 is relatively smooth, and the average particle size is about 77 μm.

[0243] Based on the morphology of the rust-transforming microcapsule A2 after compression and crushing, it can be seen that the rust-transforming microcapsule A2 has a typical "core-shell" structure with a capsule wall thickness of about 6 μm.

[0244] Test Example 2

[0245] The FTIR spectra of the self-healing microcapsule A3 from Example 3 and the self-healing microcapsule A3 after extrusion and crushing were detected using an infrared spectrometer (Frontier, PerkinElmer). Figure 4 ;

[0246] According to Figure 4 There are microcapsules in 3326 cm -1 , 1625 cm -1 , 1580 cm -1 The infrared absorption peaks at 2253 cm -1 , 3425 cm -1 and 1180 cm -1 appeared after the microcapsules were crushed to form a mixture of the core and the wall of the capsule, and the -NCO characteristic peak of hexamethylene diisocyanate, and the -OH stretching vibration peak and C-O-C vibration absorption peak of graphene oxide, which proved that the hexamethylene diisocyanate and graphene oxide were successfully encapsulated inside the urea-formaldehyde resin capsule wall of the self-healing microcapsule A3.

[0247] Test Example 3

[0248] The self-repairing anticorrosive coating A1 obtained in Example 1, the self-repairing anticorrosive coating D1 obtained in Comparative Example 1, the self-repairing anticorrosive coating D2 obtained in Comparative Example 2, and the self-repairing anticorrosive coating D3 obtained in Comparative Example 3 were respectively coated on the Q235 carbon steel sheet (Shengxin Technology, Shandong) with surface polishing and rust removal, and the coating thickness was the same. Then, the coating was cured at room temperature for 7 days. Then, a through scratch with a width of 100 μm was prepared on the surface of each coating by hand knife, and the four scratch coating samples were immersed in a 3.5 wt% NaCl solution for corrosion for 480 h. A three-electrode test system was established with the scratch coating sample after immersion corrosion as the working electrode, the Ag / AgCl electrode as the reference electrode, and the platinum metal as the auxiliary electrode. The electrochemical impedance spectrum of the scratch coating sample after immersion corrosion was tested, and the experimental results are shown in Figure 5

[0249] The Figure 5 measured data was fitted according to the method described in "Introduction to Electrochemical Impedance Spectroscopy" (Cao Chunan, Zhang Jianqing, 2016). The equivalent circuit was R s (Q c (R c (R ct Q ct ))).Among them, R c characterizes the barrier ability of the coating part after scratch healing to the corrosion medium, and R ct characterizes the shielding performance of the material on the surface of the carbon steel substrate at the scratch to the corrosion medium. The fitting results are shown in Table 1.

[0250] Table 1

[0251] Name [R c / Ω·cm 2 ]]> [R ct / Ω·cm 2 ]]> Self-repairing anticorrosive coating A1 5.74 x 10 6 ]] 6.21 x 10 5 ]]> Self-repairing anticorrosive coating D1 2.84 x 10 4 ]]> 9.25 x 10 3 ]]> Self-repairing anticorrosive coating D2 3.23 x 10 6 ]]> 2.26 x 10 4 ]]> Self-repairing anticorrosive coating D3 4.47 x 10 5 ]]> 4.83 x 10 5 ]]>

[0252] According toFigure 5 As can be seen from the results of self-repairing anticorrosive coating A1 and self-repairing anticorrosive coating D1 in Table 1, when the self-healing microcapsules and the red rust conversion microcapsules are incorporated into the coating, the overall corrosion intensity of the scratch coating during immersion in the corrosion medium is significantly reduced, and the corrosion resistance of the coating is improved. The corrosion resistance principle of the coating after scratch repair can be described as follows: the scratch position of the coating of Comparative Example 1 provides a channel for the penetration of the corrosion medium, and the loose corrosion products generated on the surface of the base metal are difficult to play a barrier role, so the overall corrosion degree is large; the self-healing microcapsules and the red rust conversion microcapsules in the coating of Example 1 can release graphene oxide modified isocyanate capsule cores and composite rust conversion agent capsule cores at the scratch position, respectively, to locally form polyurethane repair materials and inert protective layers with good barrier effect, thereby enhancing the medium shielding performance of the coating after scratch repair. Figure 6

[0253] As can be seen from the comparison of the experimental results of self-repairing anticorrosive coating A1 and self-repairing anticorrosive coating D2, the red rust conversion microcapsules in the coating can induce the formation of an inert protective layer on the surface of the base metal at the scratch position, thereby weakening the intensity of local corrosion.

[0254] As can be seen from the comparison of the experimental results of self-repairing anticorrosive coating A1 and self-repairing anticorrosive coating D3, after the incorporation of graphene oxide, the uniformly dispersed sheet-shaped graphene oxide filler in the healing product can prolong the diffusion and penetration path of the corrosive medium to the substrate, thereby improving the barrier performance of the coating after scratch repair.

[0255] Test Example 4

[0256] Self-repairing anticorrosive coating A1 obtained in Example 1, self-repairing anticorrosive coating A2 obtained in Example 2, self-repairing anticorrosive coating A3 obtained in Example 3, self-repairing anticorrosive coating A4 obtained in Example 4, self-repairing anticorrosive coating D1 obtained in Comparative Example 1, self-repairing anticorrosive coating D2 obtained in Comparative Example 2, self-repairing anticorrosive coating D3 obtained in Comparative Example 3, and self-repairing anticorrosive coating D4 obtained in Comparative Example 4 were respectively coated on Q235 carbon steel sheets (Shandong Shengxin Technology) with the surface polished and rusted, and the coating thickness was the same. Then, the coating was cured at room temperature for 7 days. Then, a through scratch with a width of 100 μm was prepared on the surface of each coating with a hand tool, and the four scratch coating samples were immersed in a 3.5 wt% NaCl solution for corrosion for 480 h.

[0257] According to the adhesion test method specified in the national standard GB / T 5210-2006 “Color Paint and Varnish Pull-off Method Adhesion Test”, the adhesion of self-repairing anticorrosive coating A1, self-repairing anticorrosive coating A2, self-repairing anticorrosive coating A3, self-repairing anticorrosive coating A4, self-repairing anticorrosive coating D1, self-repairing anticorrosive coating D2, self-repairing anticorrosive coating D3, and self-repairing anticorrosive coating D4 after immersion corrosion was tested, and the results are shown in Table 2.​

[0258] Table 2

[0259] Name Adhesion / MPa Self-repairing anticorrosive coating A1 6.35 Self-repairing anticorrosive coating A2 6.21 Self-repairing anticorrosive coating A3 6.49 Self-repairing anticorrosive coating A4 6.36 Self-repairing anticorrosive coating D1 4.13 Self-repairing anticorrosive coating D2 5.07 Self-repairing anticorrosive coating D3 6.02 Self-repairing anticorrosive coating D4 5.41

[0260] According to the results of Table 2, it can be seen that the addition of the rust conversion microcapsule in the coating can increase the adhesion of the coating after repair, and the reason is that the complex rust conversion agent in the rust conversion microcapsule can react with the rust at the scratch to form a high-adhesion substance, thereby preventing the coating from peeling off and other failure conditions during long-term immersion. In addition, compared with a single penetration-type rust conversion agent, the use of a complex rust conversion agent can further enhance the adhesion of the coating after repair and improve the mechanical properties of the coating.

[0261] Test Example 5

[0262] The self-repairing anticorrosive coating A1 obtained in Example 1 and the self-repairing anticorrosive coating D2 obtained in Comparative Example 2 were respectively coated on Q235 carbon steel sheets (Shandong Shengxin Technology) with rust removed by surface grinding, and the coating thickness was the same. Then, the coatings were cured at room temperature for 7 days. Then, a hand knife was used to prepare through scratches with a width of 100 μm on the surface of each coating, and the four scratch coating samples were immersed in a 3.5 wt% NaCl solution for corrosion for 480 h.

[0263] The surface optical micro-morphology of the self-repairing anticorrosive coatings A1 and D2 after immersion corrosion was observed by using a projection microscope (MXB-2500, Japan Haoshixing), as shown in FIG. 2. Figure 7

[0264] According to Figure 7 It can be seen that the self-repairing anticorrosive coating developed in the present application can be self-healed by the graphene-modified isocyanate in the self-healing microcapsule flowing into the scratch and polymerizing with the corrosion solution to form polyurethane substances to effectively fill the scratch damage site, so that the coating can be self-healed in this process. The rust conversion microcapsule in the coating contains a complex rust conversion agent, which can be hydrolyzed into phosphate ions at the initial stage of immersion and react with the loose rust on the surface of the base metal to form Fe[Zn3(PO4)2(RCOO)4]3, Fe-Zn-P2O5 and other iron-based heteropoly acid complexes, which can prevent the spread of metal corrosion and prevent the occurrence of the base metal rusting phenomenon under the repair layer as described in Comparative Example 2.

[0265] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as disclosed in the present application and fall within the protection scope of the present application.​

Claims

1. A method for preparing a self-repairing anticorrosive coating, characterized by, The preparation method comprises the following steps: (1) mixing self-healing microcapsules, rust conversion microcapsules and epoxy resin; (2) mixing the material obtained in step (1), adhesion promoter, toughening agent, leveling agent and anti-settling agent, and then standing to obtain an epoxy resin mixture; (3) mixing the epoxy resin mixture and a curing agent, and then standing to obtain a self-repairing anticorrosive coating; The core of the self-healing microcapsule is graphene oxide modified isocyanate; The core of the rust conversion microcapsule is a composite rust conversion agent; The composite rust conversion agent is obtained by compounding a permeable rust conversion agent and a stable rust conversion agent.

2. The method for preparing a self-repairing anticorrosive coating according to claim 1, characterized in that, The weight ratio of the self-healing microcapsules, the rust conversion microcapsules, the epoxy resin, the curing agent, the adhesion promoter, the toughening agent, the leveling agent and the anti-settling agent is 6-13:5-11:50:20-30:0.5-1.5:4-8:0.5-1.5:0.1-0.

8.

3. The method for preparing a self-repairing anticorrosive coating according to claim 1 or 2, characterized in that, In step (1), the mixing conditions include mixing at a stirring speed of 400-600 r / min for 30-60 min.

4. The method for preparing a self-repairing anticorrosive coating according to claim 1 or 2, characterized in that, In step (2), the mixing conditions include mixing at a stirring speed of 800-1200 r / min for 30-60 min.

5. The method for preparing a self-repairing anticorrosive coating according to claim 1 or 2, characterized in that, In step (2), the standing time is 48-72 h.

6. The method for preparing a self-repairing anticorrosive coating according to claim 1 or 2, characterized in that, In step (3), the mixing conditions include mixing at a stirring speed of 600-1000 r / min for 30-50 min.

7. The method of preparing a self-repairing anticorrosive coating according to claim 1 or 2, characterized in that, In step (3), the standing time is 4-8 h.

8. The method of claim 1, wherein the self-repairing anticorrosive coating is prepared by the steps of: The epoxy resin is selected from one or two or more of bisphenol A type epoxy resin E-33, bisphenol A type epoxy resin E-35, bisphenol A type epoxy resin E-42, bisphenol A type epoxy resin E-44, bisphenol A type epoxy resin E-51, bisphenol A type epoxy resin E-55, bisphenol F type epoxy resin DER-351, bisphenol F type epoxy resin DER-352, bisphenol F type epoxy resin DER-356, glycidyl ester type epoxy resin, phenolic epoxy resin EPN-1138, phenolic epoxy resin EPN-1179, phenolic epoxy resin EPN-1183, phenolic epoxy resin DEN-431 and phenolic epoxy resin DEN-438.

9. The method of claim 1 or 8, wherein the self-repairing anticorrosive coating is prepared by the steps of: The adhesion promoter is selected from one or two or more of BYK-4509, BYK-4510, BYK-4511 and BYK-4512.

10. The method of preparing a self-repairing anticorrosive coating according to claim 1 or 8, characterized in that, The toughening agent is selected from one or two or more of F-100, F-201 and F-202.

11. The method of preparing a self-repairing anticorrosive coating according to claim 1 or 8, characterized in that, The leveling agent is selected from one or two or more of BYK-397, ECO-3758 and ECO-3880.

12. The method of preparing a self-repairing anticorrosive coating according to claim 1 or 8, characterized in that, The anti-settling agent is selected from one or two or more of fumed silica UG-SP15G, fumed silica R972, fumed silica HT-822 and fumed silica HT-900.

13. The method of claim 1 or 8, wherein the self-repairing anticorrosive coating is prepared by the steps of: The curing agent is selected from one or two or more of diethylene triamine, triethylene tetramine, N,N-dimethyl aminopropylamine, 3-diethyl aminopropylamine and hydroxyethyl ethylenediamine.

14. The method for preparing the self-healing anti-corrosion coating according to claim 1, characterized in that, The preparation method of the self-healing microcapsule comprises: S1: mixing graphene oxide and isocyanate in a weight ratio of 1:49-99, and then performing ultrasonic dispersion to obtain graphene oxide modified isocyanate capsule core; S2: mixing urea, resorcinol, ammonium chloride, water, emulsifier A solution, co-emulsifier A, and graphene oxide modified isocyanate capsule core; S3: adjusting the pH value of the emulsion obtained in step S2 to 3-4, then adding dropwise formaldehyde solution, followed by ultrasonic dispersion, and finally performing reaction under stirring; S4: washing and vacuum drying the material obtained in step S3.

15. The method of claim 14, wherein the self-healing anticorrosive coating is prepared by a process comprising: In step S1, the number of layers of the graphene oxide sheet is 1-20 layers, and the size of the microsheet is 5-25 μm.

16. The method of preparing a self-repairing anticorrosive coating according to claim 14 or 15, characterized in that, In step S1, the isocyanate is selected from one or two or more of hexamethylene diisocyanate, hexamethylene diisocyanate trimer, isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, L-lysine diisocyanate, norbornane dimethylene isocyanate, phenylene dimethylene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate.

17. The method of claim 14, wherein the self-healing anticorrosive coating is prepared by a process comprising: In step S1, the ultrasonic dispersion time is 10-20 min.

18. The method of claim 14, wherein the self-healing anticorrosive coating is prepared by a process comprising: The weight ratio of the urea, resorcinol, ammonium chloride, water, emulsifier A solution, co-emulsifier A, graphene oxide modified isocyanate capsule core, and formaldehyde solution is 4-8:1:0.5-2:150-400:10-25:1-4:7-24:8-30.

19. The method of preparing a self-repairing anticorrosive coating according to claim 14 or 18, characterized in that, The concentration of the emulsifier A solution is 2-5 wt%.

20. The method of claim 14 or 18, wherein the self-repairing anticorrosive coating is prepared by the steps of: The emulsifier A is selected from sodium dodecylbenzenesulfonate and / or sodium dodecyl sulfate.

21. The method of preparing a self-repairing anticorrosive coating according to claim 14 or 18, characterized in that, The co-emulsifier A is selected from one or two or more of n-butanol, propylene glycol, and glycerol.

22. The method of claim 14 or 18, wherein the self-repairing anticorrosive coating is prepared by the steps of: The concentration of the formaldehyde solution is 35-40 wt%.

23. The method of preparing a self-repairing anticorrosive coating according to claim 14 or 15, characterized in that, The process of step S2 includes: mixing urea, resorcinol, ammonium chloride, and water to obtain a mixed solution; then mixing the mixed solution, emulsifier A solution, and co-emulsifier A under stirring for 30-60 min, followed by dropwise addition of graphene oxide modified isocyanate capsule core, and continuing to mix for 45-60 min after the dropwise addition of graphene oxide modified isocyanate capsule core is completed.

24. The method of claim 23, wherein the self-healing anticorrosive coating is prepared by a method comprising: The stirring speed is 400-600 r / min.

25. The method for preparing the self-healing anti-corrosion coating according to claim 14, characterized in that, In step S3, the ultrasonic dispersion conditions include a temperature of 0-5℃, a time of 15-40 min, and an ultrasonic power of 20-35 kHz.

26. The method of claim 14, wherein the self-healing anticorrosive coating is prepared by a method comprising: In step S3, the stirring speed is 650-900 r / min.

27. The method of preparing a self-repairing anticorrosive coating according to claim 14 or 26, characterized in that, In step S3, the reaction conditions include heating to 50-70℃ at a heating rate of 0.5-2℃ / min and reacting for 3-5 h.

28. The method for preparing the self-healing anti-corrosion coating according to claim 1, characterized in that, The preparation method of the rust conversion microcapsule includes: (a) dispersing and grinding a permeable rust conversion agent and a stable rust conversion agent in a weight ratio of 5-9:1 to obtain a composite rust conversion agent capsule core; (b) mixing urea, resorcinol, ammonium chloride, water, emulsifier B solution, co-emulsifier B, and composite rust conversion agent capsule core; (c) adjusting the pH value of the emulsion obtained in step (b) to 3-4, then adding dropwise a formaldehyde solution, followed by ultrasonic dispersion, and finally reacting under stirring; (d) washing and vacuum drying the material obtained in step (c).

29. The method of claim 28, wherein the self-healing anticorrosive coating is prepared by a process comprising: In step (a), the penetrating rust conversion agent is selected from one or more than two of linseed oil, dehydrated rust preventive oil, oxidized fish oil and rust preventive paraffin oil.

30. The method of preparing a self-repairing anticorrosive coating according to claim 28 or 29, characterized in that, In step (a), the stable rust conversion agent is selected from one or more than two of aluminum tripolyphosphate, aluminum dihydrogen tripolyphosphate, zinc phosphate, zinc oxide and zinc chromate.

31. The method of claim 28, wherein the self-healing anticorrosive coating is prepared by, In step (a), the dispersion grinding conditions include: dispersion grinding at a rotation speed of 2000-4000 r / min for 30-60 min.

32. The method of preparing a self-repairing anticorrosive coating according to claim 28, characterized in that, The weight ratio of the urea, resorcinol, ammonium chloride, water, emulsifier B solution, co-emulsifier B, composite rust conversion agent core and formaldehyde solution is 4-8:1:0.5-2:150-400:15-40:1-4:6-15:8-30.

33. The method of preparing a self-repairing anticorrosive coating according to claim 28 or 32, characterized in that, The concentration of the emulsifier B solution is 2-5 wt%.

34. The method of preparing a self-repairing anticorrosive coating according to claim 28 or 32, characterized in that, The emulsifier B is selected from sodium dodecyl benzene sulfonate and / or sodium dodecyl sulfate.

35. The method of preparing a self-repairing anticorrosive coating according to claim 28 or 32, characterized in that, The co-emulsifier B is selected from one or more than two of n-butanol, propylene glycol and glycerol.

36. The method of preparing a self-repairing anticorrosive coating according to claim 28 or 32, characterized in that, The concentration of the formaldehyde solution is 35-40 wt%.

37. The method of preparing a self-repairing anticorrosive coating according to claim 28 or 32, characterized in that, The process of step (b) includes: mixing urea, resorcinol, ammonium chloride and water to obtain a mixed solution; then mixing the mixed solution, emulsifier B solution and co-emulsifier B under stirring for 30-60 min, followed by dropwise addition of the composite rust conversion agent core, and continuing to mix for 45-60 min after the dropwise addition of the composite rust conversion agent core is completed.

38. The method of preparing a self-repairing anticorrosive coating according to claim 37, characterized in that, The stirring speed is 400-600 r / min.

39. The method of preparing a self-repairing anticorrosive coating according to claim 28, characterized in that, In step (c), the ultrasonic dispersion conditions include: a temperature of 0-5℃, a time of 15-40 min and an ultrasonic power of 20-35 kHz.

40. The method of claim 28, wherein the self-healing anticorrosive coating is prepared by, In step (c), the stirring speed is 1000-2000 r / min.

41. The method of preparing a self-repairing anticorrosive coating according to claim 28 or 40, characterized in that, In step (c), the reaction conditions include: heating to 50-70℃ at a heating rate of 0.5-2℃ / min and reacting for 3-5 h.

42. The self-repairing anticorrosive coating prepared by the method of any one of claims 1-41.

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