An epoxy coating maintenance agent, its preparation method and application

Abstract

The application provides an epoxy coating maintenance agent and a preparation method and application thereof, and the maintenance agent comprises water, a compatibilizer, an organic corrosion inhibitor, a coating activator, ethanol, gamma-aminopropyl triethoxysilane, methyltrimethoxysilane, a catalyst and nano silicon dioxide. The epoxy coating maintenance agent utilizes the synergistic effect of MTMS and APS, the silanol groups of the co-hydrolysis condensation product of the two condense with the coating defect surface, and the amino groups of APS react with the coating residual groups, and meanwhile, the synergistic effect is fully exerted by compounding with the compatibilizer, the organic corrosion inhibitor, the coating activator and the nano silicon dioxide, the epoxy coating maintenance agent can penetrate into the deep coating defects, activate the coating defect surface groups, create a firm and dense "organic-inorganic hybrid silicon-oxygen network" on the coating defect surface and inside, and thus realize deep repair and long-acting maintenance of the epoxy coating.

Description

Technical Field

[0001] This invention belongs to the field of coating composition technology, and in particular relates to an epoxy coating maintenance agent, its preparation method and application. Background Technology

[0002] Epoxy coatings, due to their excellent adhesion, chemical corrosion resistance, mechanical strength, and abrasion resistance, have become one of the most critical protective coatings in industrial and civil fields. They are widely used in key infrastructure and industrial facilities such as bridges, ports, petrochemical pipelines, storage tanks, factory floors, ships, and offshore platforms, playing a vital role in isolating corrosive media, extending the lifespan of the substrate, and ensuring structural safety.

[0003] However, in actual operation, a common and increasingly prominent contradiction is the "emphasis on coating application and neglect of maintenance." Many projects invest heavily in surface treatment and coating application during the construction phase, but lack a systematic and scientific coating maintenance management system throughout the decades-long operation cycle. Coatings are exposed to complex environmental stresses such as ultraviolet radiation, temperature and humidity cycles, chemical corrosion, mechanical wear, impact, and microorganisms for extended periods, inevitably leading to defects such as aging, chalking, cracking, blistering, peeling, and pinholes. If these initial minor defects are not detected and repaired in time, they become rapid channels for the intrusion of moisture, oxygen, and corrosive ions, resulting in hidden corrosion of the substrate. The volume expansion of corrosion products further exacerbates coating peeling, forming a vicious cycle of "accelerated defect propagation—substrate corrosion—accelerated coating failure," ultimately causing the coating's protective function to be lost prematurely.

[0004] To improve the service life of epoxy coatings, existing technologies typically add self-healing components to the epoxy coating. For example, Chinese invention patent CN114133836A discloses a microcapsule-type self-healing fusion-bonded epoxy coating and its preparation method, which adds epoxy resin microcapsules and amine curing agent microcapsules to the base component fusion-bonded epoxy powder, allowing the epoxy coating to self-repair when damaged. Chinese invention patent CN120082265A discloses a high-strength, high-toughness, low-temperature seawater self-healing epoxy coating, its preparation method, and its application. This involves a modified epoxy adaptive network material prepared by reacting epoxy resin, polyol, diisocyanate, and monomers containing dynamic chemical bonds, and a modified Ti3C2T modified with dopamine and a modifier containing four-fold hydrogen bond motifs. x Modified Ti3C2T obtained from MXene x Two-dimensional nanosheets undergo an ordered interfacial cross-linking reaction to produce a high-strength, high-toughness, self-healing epoxy coating for low-temperature seawater environments. While this method can improve the epoxy coating's damage resistance, self-healing ability, and extend its service life to some extent, it significantly increases production costs. Furthermore, the repair effect of the epoxy coating decreases as the self-healing components are depleted.

[0005] Therefore, there is an urgent need to develop a high-efficiency epoxy coating maintenance agent that provides deep repair, long-term maintenance, good results, simple construction, and low cost. Summary of the Invention

[0006] In view of this, the present invention aims to provide an epoxy coating maintenance agent, its preparation method and application, in order to solve the current problems of lack of maintenance methods and materials for epoxy coatings.

[0007] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0008] In a first aspect, the present invention provides an epoxy coating maintenance agent, wherein the maintenance agent comprises, by weight parts: 1200 parts water, 15 to 100 parts compatibilizer, 15 to 100 parts organic corrosion inhibitor, 15 to 100 parts coating activator, 400 parts ethanol, 15 to 100 parts γ-aminopropyltriethoxysilane, 15 to 100 parts methyltrimethoxysilane, 0.01 to 0.2 parts catalyst, and 15 to 100 parts nano-silica.

[0009] Furthermore, the compatibilizer includes diisopropyl di(triethanolamine)titanate.

[0010] Furthermore, the organic corrosion inhibitor includes one or more of hexadecylamine, diethylaminoethanol, and imidazoline quaternary ammonium salt.

[0011] Furthermore, the coating activator includes one or more of industrial-grade N-methylpyrrolidone (NMP), industrial-grade dimethyl sulfoxide (DMSO), and industrial-grade propylene glycol.

[0012] Furthermore, the ethanol meets the requirements of "Industrial Ethanol" (GB / T 6820-2016).

[0013] Furthermore, the γ-aminopropyltriethoxysilane meets the requirements of "Aminosilane Coupling Agents" (HG / T 4892-2016).

[0014] Furthermore, the methyltrimethoxysilane meets the requirements of "Methyltrimethoxysilane for Industrial Use" (GB / T 35501-2017).

[0015] Further, the catalyst comprises industrial-grade hydrochloric acid; preferably, the concentration of the hydrochloric acid is 30% to 45%, for example, it can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%; more preferably 37%.

[0016] Furthermore, the nano-silica particles have a diameter of 10~500nm and a pH of 7~8.

[0017] After a period of use, epoxy coatings will develop defects at the molecular, micron, or even nano level inside or on their surface. This requires the curing agent to not only penetrate and compensate for molecular-level defects, but also to fill in micron- or nano-level defects, while also repairing chalking and improving discoloration.

[0018] In the epoxy coating maintenance agent of the present invention, the coating activator is well compatible with the maintenance agent system. After the epoxy coating maintenance agent is applied to the epoxy coating, it can also quickly penetrate into the defects of the epoxy coating, so that the epoxy coating surface and defects are in an activated state, creating good conditions for other components to fully penetrate, react and block.

[0019] Methyltrimethoxysilane (MTMS) and γ-aminopropyltriethoxysilane (APS) have a synergistic effect. Their co-hydrolysis condensation products are rich in silanol groups (-SiOH), which can undergo condensation reactions with the defective surface of epoxy coatings. Furthermore, the amino group (-NH2) provided by APS can chemically react with the residual epoxy or carboxyl groups in the epoxy coating, forming strongly anchored, robust, and dense "organic-inorganic hybrid siloxane" active particles on the surface of the old coating and inside the micro-defects. While bridging the micro-defects of the coating, MTMS provides hydrophobic methyl groups (-CH3), which endow the new network with excellent hydrophobicity and can effectively block water penetration.

[0020] The hydrolysis products of the compatibilizer have excellent compatibility with epoxy resin and can spread rapidly on the surface of epoxy coating defects. At the same time, the compatibilizer (diisopropyl di(triethanolamine)titanate) can also undergo partial hydrolysis and polycondensation with the co-hydrolysis condensation products of MTMS and APS to form nano-sized active prepolymers, which promotes good penetration of the co-hydrolyzed nano-sized particles and fully repairs micro defects.

[0021] Nano-silica and the above prepolymer form active filler aggregates in the range of hundreds of nanometers, which can perfectly repair micron-level defects and build a strong physical barrier to effectively block the intrusion of corrosive media such as water, chloride ions, and oxygen.

[0022] Meanwhile, the organic corrosion inhibitor in the epoxy coating maintenance agent of this invention can accumulate at the defects of the epoxy coating. Even if a small amount of corrosive medium penetrates, it can penetrate along with the corrosive medium and form a protective film on the surface of the carbon steel substrate, providing additional chemical protection and achieving a dual maintenance effect of "physical + chemical".

[0023] The epoxy coating maintenance agent of the present invention is an aqueous liquid system, the viscosity of which can be adjusted by adding water. It can be applied by brushing, rolling or spraying without complicated equipment. It is particularly suitable for online maintenance of in-service equipment without large-scale production shutdown.

[0024] Compared to the costly "re-recoating" process required by existing technologies after complete coating failure, the epoxy coating maintenance agent of this invention allows for regular or early preventative maintenance. This extends the service life of the coating by several times at a very low cost (approximately 1%-10% of the cost of recoating), minimizing the total life-cycle cost of the asset. Simultaneously, by proactively repairing micro-defects and preventing their expansion into macro-failure, it fundamentally eliminates substrate corrosion, structural safety hazards, and potential environmental leakage risks caused by coating failure, ensuring operational safety and production continuity.

[0025] In a second aspect, the present invention provides a method for preparing the epoxy coating maintenance agent as described in the first aspect, the method comprising the following steps:

[0026] S1. Stir the ethanol and catalyst evenly to obtain a mixed solution;

[0027] S2. Add methyltrimethoxysilane, γ-aminopropyltriethoxysilane and compatibilizer sequentially to the mixed solution obtained in step S1, heat the reaction and then cool down to obtain the reaction product.

[0028] S3. Add organic corrosion inhibitor, coating activator and nano silica to the reaction product obtained in step S2 in sequence, stir evenly, then add water and stir evenly to obtain the epoxy coating maintenance agent.

[0029] Furthermore, in step S1, ethanol, as an inert polar solvent, first disperses the catalyst to form a homogeneous catalytic system, which can avoid the reaction runaway caused by excessively high local concentration of catalyst, and provide a stable reaction medium for the subsequent hydrolysis and condensation of silane coupling agent, ensuring uniform catalytic efficiency.

[0030] Furthermore, in step S1, the stirring temperature is 25~30℃ and the stirring speed is 50~80rpm.

[0031] Furthermore, in step S1, the stirring time is 5-10 minutes.

[0032] Further, in step S2, methyltrimethoxysilane is first added as the film-forming main agent. It has a moderate hydrolysis rate and mild activity, and preferentially undergoes hydrolysis condensation to form a linear polysiloxane backbone, laying the foundation for the film-forming framework and basic weather resistance of the maintenance agent. Then, γ-aminopropyltriethoxysilane is added. It contains active amino groups, is highly basic, and has a high tendency to self-polymerize. Adding it later can avoid premature self-polymerization and excessive reaction with the catalyst. After the main silane forms a prepolymer, it is added to ensure precise graft copolymerization, improve the adhesion and crosslinking density with the epoxy coating, and provide rust prevention and surface activation functions. After the silane reacts, the polarity of the system changes. Finally, a compatibilizer is added to adjust the compatibility of the organic / inorganic phases, prevent phase separation and stratification, and ensure that the reaction product is uniform and transparent. Warm-promoted hydrolysis condensation and cooling to terminate the reaction stabilize the prepolymer structure and avoid excessive crosslinking and gelation.

[0033] Furthermore, in step S2, the reaction temperature is 35~38℃, the reaction time is 8~12h, and the temperature after cooling is 25~30℃.

[0034] Furthermore, in step S2, the addition rate of methyltrimethoxysilane, γ-aminopropyltriethoxysilane, and compatibilizer is 20~30 L / h.

[0035] Thirdly, the present invention provides a method for maintaining an epoxy coating, which uses the epoxy coating maintenance agent as described in the first aspect, the method comprising the step of applying the epoxy coating maintenance agent to the surface of the epoxy coating.

[0036] Fourthly, the present invention provides the application of the epoxy coating maintenance agent according to the first aspect in improving the durability of epoxy coatings;

[0037] Preferably, the application includes at least one of the following:

[0038] (1) Application in improving the anti-bubbling properties of epoxy coatings;

[0039] (2) Application in improving the corrosion resistance of epoxy coatings;

[0040] (4) Application in improving the crack resistance of epoxy coatings;

[0041] (5) Application in improving the anti-peeling properties of epoxy coatings;

[0042] (6) Application in improving the corrosion resistance of epoxy coatings;

[0043] (7) Application in improving the adhesion of epoxy coatings.

[0044] Compared with existing technologies, the epoxy coating maintenance agent, its preparation method, and its application described in this invention have the following advantages:

[0045] (1) The epoxy coating maintenance agent of the present invention utilizes the synergistic effect of MTMS and APS. The silanol group of the co-hydrolysis condensation product of the two condenses with the surface of the coating defect, and the amino group of APS reacts with the residual group of the coating. At the same time, by compounding with compatibilizer, organic corrosion inhibitor, coating activator and nano silica, the synergistic effect is fully utilized, which can penetrate into the depth of the coating defect, activate the group on the surface of the coating defect, and create a strong and dense "organic-inorganic hybrid silicon-oxygen network" on the surface and inside of the coating defect, thereby achieving deep repair and long-term maintenance of epoxy coating.

[0046] (2) This invention creatively proposes an epoxy coating maintenance method that replaces recoating with curing. The epoxy coating curing agent can extend the service life of the epoxy coating at extremely low cost, actively repair micro-defects in the epoxy coating, and meet the requirements of safe and continuous production.

[0047] (3) The epoxy coating maintenance agent of the present invention improves the compatibility with epoxy resin by adding compatibilizer, so that the maintenance agent can be quickly spread on the surface of epoxy coating defects. At the same time, the compatibilizer can also partially hydrolyze and condense with the co-hydrolysis condensation products of MTMS and APS, promoting the good penetration of the co-hydrolyzed nano-sized particles and fully repairing the micro defects.

[0048] (4) The epoxy coating maintenance agent of the present invention can accumulate at the defects of the epoxy coating by adding organic corrosion inhibitors, and penetrate into the depth of the defects along with the corrosive medium to form a protective film on the substrate surface, providing additional chemical protection and achieving a dual maintenance effect of "physical + chemical". Detailed Implementation

[0049] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0050] The present invention will be described in detail below with reference to the embodiments. Unless otherwise specified, the raw materials used in the following embodiments are all commercially available products; among them, water must meet the "Standards for Drinking Water Quality" (GB5749), diisopropyl di(triethanolamine)titanate has a purity of not less than 99%, N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), propylene glycol, hexadecylamine, diethylaminoethanol, and imidazoline quaternary ammonium salt are all industrial grade, ethanol must meet the "Industrial Ethanol" (GB / T 6820-2016), γ-aminopropyltriethoxysilane must meet the "Aminosilane Coupling Agents" (HG / T 4892-2016), methyltrimethoxysilane must meet the "Industrial Methyltrimethoxysilane" (GB / T 35501-2017), hydrochloric acid is industrial grade hydrochloric acid with a mass concentration of 37%, and nano-silica has an average particle size of 10~500 nm and a pH value of 7~8.

[0051] Example 1

[0052] Weigh out the following components by weight: 1200 parts water, 15 parts diisopropyl di(triethanolamine)titanate, 15 parts hexadecylamine, 15 parts N-methylpyrrolidone, 400 parts ethanol, 15 parts γ-aminopropyltriethoxysilane, 15 parts methyltrimethoxysilane, 0.01 parts hydrochloric acid, and 15 parts nano-silica.

[0053] Ethanol was added to a dispersion tank at 25°C and stirred at 50 rpm. Hydrochloric acid was added and stirred for 5 min until homogeneous. Methyltrimethoxysilane was slowly added at a rate of 20 L / h and stirred until homogeneous. γ-aminopropyltriethoxysilane was slowly added at a rate of 20 L / h and stirred until homogeneous. Diisopropyl di(triethanolamine)titanate was slowly added at a rate of 20 L / h and stirred until homogeneous. The temperature was raised to 35°C and reacted for 8 h. The temperature was lowered to 25°C, and hexadecylamine, N-methylpyrrolidone, and nano-silica were added sequentially and stirred for 30 min. Finally, water was added and dispersed until homogeneous to obtain the epoxy coating maintenance agent.

[0054] Example 2

[0055] Weigh out the following components by weight: 1200 parts water, 100 parts diisopropyl di(triethanolamine)titanate, 100 parts diethylaminoethanol, 100 parts dimethyl sulfoxide, 400 parts ethanol, 100 parts γ-aminopropyltriethoxysilane, 100 parts methyltrimethoxysilane, 0.2 parts hydrochloric acid, and 100 parts nano-silica.

[0056] Ethanol was added to a dispersion tank at 30°C and stirred at 80 rpm. Hydrochloric acid was added and stirred for 10 min until homogeneous. Methyltrimethoxysilane was slowly added at 30 L / h and stirred until homogeneous. γ-aminopropyltriethoxysilane was slowly added at 30 L / h and stirred until homogeneous. Diisopropyl di(triethanolamine)titanate was slowly added at 30 L / h and stirred until homogeneous. The temperature was raised to 38°C and reacted for 12 h. The temperature was lowered to 30°C, and diethylaminoethanol, dimethyl sulfoxide, and nano-silica were added sequentially and stirred for 30 min. Finally, water was added and dispersed until homogeneous to obtain the epoxy coating maintenance agent.

[0057] Example 3

[0058] Weigh out the following components by weight: 1200 parts water, 50 parts diisopropyl di(triethanolamine)titanate, 50 parts imidazoline quaternary ammonium salt, 50 parts propylene glycol, 400 parts ethanol, 50 parts γ-aminopropyltriethoxysilane, 50 parts methyltrimethoxysilane, 0.08 parts hydrochloric acid, and 50 parts nano silica.

[0059] Ethanol was added to a dispersion tank at 26°C and stirred at 60 rpm. Hydrochloric acid was added and stirred for 60 min until homogeneous. Methyltrimethoxysilane was slowly added at a rate of 25 L / h and stirred until homogeneous. γ-aminopropyltriethoxysilane was slowly added at a rate of 25 L / h and stirred until homogeneous. Diisopropyl di(triethanolamine)titanate was slowly added at a rate of 25 L / h and stirred until homogeneous. The temperature was raised to 36°C and reacted for 9 h. The temperature was lowered to 26°C, and imidazoline quaternary ammonium salt, propylene glycol, and nano silica were added sequentially and stirred for 30 min. Finally, water was added and dispersed until homogeneous to obtain the epoxy coating maintenance agent.

[0060] Example 4

[0061] Weigh out the following components by weight: 1200 parts water, 80 parts diisopropyl di(triethanolamine)titanate, 25 parts hexadecylamine, 25 parts diethylaminoethanol, 25 parts imidazoline quaternary ammonium salt, 50 parts N-methylpyrrolidone, 25 parts dimethyl sulfoxide, 25 parts propylene glycol, 400 parts ethanol, 50 parts γ-aminopropyltriethoxysilane, 15 parts methyltrimethoxysilane, 0.1 parts hydrochloric acid, and 75 parts nano-silica.

[0062] Ethanol was added to a dispersion tank at 28°C and stirred at 70 rpm. Hydrochloric acid was added and stirred for 8 minutes until homogeneous. Methyltrimethoxysilane was slowly added at a rate of 22 L / h and stirred until homogeneous. γ-aminopropyltriethoxysilane was slowly added at a rate of 22 L / h and stirred until homogeneous. Diisopropyl di(triethanolamine)titanate was slowly added at a rate of 22 L / h and stirred until homogeneous. The temperature was raised to 35-38°C and reacted for 10 hours. The temperature was then lowered to 28°C, and hexadecylamine, diethylaminoethanol, imidazoline quaternary ammonium salt, N-methylpyrrolidone, dimethyl sulfoxide, propylene glycol, and nano-silica were added sequentially and stirred for 30 minutes. Finally, water was added and dispersed until homogeneous to obtain the epoxy coating maintenance agent.

[0063] Example 5

[0064] Weigh out the following components by weight: 1200 parts water, 50 parts diisopropyl di(triethanolamine)titanate, 75 parts hexadecylamine, 25 parts diethylaminoethanol, 15 parts N-methylpyrrolidone, 25 parts dimethyl sulfoxide, 400 parts ethanol, 25 parts γ-aminopropyltriethoxysilane, 25 parts methyltrimethoxysilane, 0.05 parts hydrochloric acid, and 25 parts nano-silica.

[0065] Ethanol was added to a dispersion tank at 24°C and stirred at 50 rpm. Hydrochloric acid was added and stirred for 6 minutes until homogeneous. Methyltrimethoxysilane was slowly added at a rate of 29 L / h and stirred until homogeneous. γ-aminopropyltriethoxysilane was slowly added at a rate of 29 L / h and stirred until homogeneous. Diisopropyl di(triethanolamine)titanate was slowly added at a rate of 29 L / h and stirred until homogeneous. The temperature was raised to 38°C and reacted for 10 hours. The temperature was lowered to 28°C, and hexadecylamine, diethylaminoethanol, N-methylpyrrolidone, dimethyl sulfoxide, and nano-silica were added sequentially and stirred for 30 minutes. Finally, water was added and dispersed until homogeneous to obtain the epoxy coating maintenance agent.

[0066] Example 6

[0067] Weigh out the following components by weight: 1200 parts water, 75 parts diisopropyl di(triethanolamine)titanate, 75 parts diethylaminoethanol, 25 parts imidazoline quaternary ammonium salt, 25 parts dimethyl sulfoxide, 75 parts propylene glycol, 400 parts ethanol, 15 parts γ-aminopropyltriethoxysilane, 15 parts methyltrimethoxysilane, 0.08 parts hydrochloric acid, and 25 parts nano-silica.

[0068] Ethanol was added to a dispersion tank at 25°C and stirred at 80 rpm. Hydrochloric acid was added and stirred for 5 minutes until homogeneous. Methyltrimethoxysilane was slowly added at a rate of 30 L / h and stirred until homogeneous. γ-aminopropyltriethoxysilane was slowly added at a rate of 30 L / h and stirred until homogeneous. Diisopropyl di(triethanolamine)titanate was slowly added at a rate of 30 L / h and stirred until homogeneous. The temperature was raised to 35°C and reacted for 12 hours. The temperature was lowered to 25°C, and diethylaminoethyl, imidazoline quaternary ammonium salt, dimethyl sulfoxide, propylene glycol, and nano-silica were added sequentially and stirred for 30 minutes. Finally, water was added and dispersed until homogeneous to obtain the epoxy coating maintenance agent.

[0069] Example 7

[0070] Weigh out the following components by weight: 1200 parts water, 25 parts diisopropyl di(triethanolamine)titanate, 25 parts hexadecylamine, 50 parts imidazoline quaternary ammonium salt, 50 parts N-methylpyrrolidone, 25 parts dimethyl sulfoxide, 25 parts propylene glycol, 400 parts ethanol, 15 parts γ-aminopropyltriethoxysilane, 75 parts methyltrimethoxysilane, 0.08 parts hydrochloric acid, and 70 parts nano-silica.

[0071] Ethanol was added to a dispersion tank at 30°C and stirred at 70 rpm. Hydrochloric acid was added and stirred for 60 min until homogeneous. Methyltrimethoxysilane was slowly added at 30 L / h and stirred until homogeneous. γ-aminopropyltriethoxysilane was slowly added at 20 L / h and stirred until homogeneous. Diisopropyl di(triethanolamine)titanate was slowly added at 30 L / h and stirred until homogeneous. The temperature was raised to 38°C and reacted for 9 h. The temperature was lowered to 25°C, and hexadecylamine, imidazoline quaternary ammonium salt, N-methylpyrrolidone, dimethyl sulfoxide, propylene glycol, and nano-silica were added sequentially and stirred for 30 min. Finally, water was added and dispersed until homogeneous to obtain the epoxy coating maintenance agent.

[0072] Example 8

[0073] Weigh out the following components by weight: 1200 parts water, 15 parts diisopropyl di(triethanolamine)titanate, 15 parts imidazoline quaternary ammonium salt, 25 parts dimethyl sulfoxide, 25 parts propylene glycol, 400 parts ethanol, 50 parts γ-aminopropyltriethoxysilane, 100 parts methyltrimethoxysilane, 0.15 parts hydrochloric acid, and 80 parts nano silica.

[0074] Ethanol was added to a dispersion tank at 22°C and stirred at 60 rpm. Hydrochloric acid was added and stirred for 10 min until homogeneous. Methyltrimethoxysilane was slowly added at a rate of 22 L / h and stirred until homogeneous. γ-aminopropyltriethoxysilane was slowly added at a rate of 22 L / h and stirred until homogeneous. Diisopropyl di(triethanolamine)titanate was slowly added at a rate of 22 L / h and stirred until homogeneous. The temperature was raised to 37°C and reacted for 11 h. The temperature was lowered to 27°C, and imidazoline quaternary ammonium salt, dimethyl sulfoxide, propylene glycol, and nano-silica were added sequentially and stirred for 30 min. Finally, water was added and dispersed until homogeneous to obtain the epoxy coating maintenance agent.

[0075] Table 1 Raw material ratios for Examples 1-8

[0076]

[0077] Comparative Example 1 (reduced amount of compatibilizer added)

[0078] The following ingredients are weighed by weight: 1200 parts water, 1 part diisopropyl di(triethanolamine)titanate, 100 parts diethylaminoethanol, 100 parts dimethyl sulfoxide, 400 parts ethanol, 100 parts γ-aminopropyltriethoxysilane, 100 parts methyltrimethoxysilane, 0.2 parts hydrochloric acid, and 100 parts nano-silica.

[0079] Ethanol was added to a dispersion tank at 25°C and stirred at 50 rpm. Hydrochloric acid was added and stirred for 10 min until homogeneous. Methyltrimethoxysilane was slowly added at a rate of 20 L / h and stirred until homogeneous. γ-aminopropyltriethoxysilane was slowly added at a rate of 20 L / h and stirred until homogeneous. Diisopropyl di(triethanolamine)titanate was slowly added at a rate of 20 L / h and stirred until homogeneous. The temperature was raised to 38°C and reacted for 12 h. The temperature was lowered to 25°C, and diethylaminoethanol, dimethyl sulfoxide, and nano-silica were added sequentially and stirred for 30 min. Finally, water was added and dispersed until homogeneous to obtain the epoxy coating maintenance agent.

[0080] Comparative Example 2 (using inorganic corrosion inhibitors instead of organic corrosion inhibitors)

[0081] Weigh out the following components by weight: 1200 parts water, 50 parts diisopropyl di(triethanolamine)titanate, 50 parts sodium nitrite (inorganic corrosion inhibitor), 50 parts propylene glycol, 400 parts ethanol, 50 parts γ-aminopropyltriethoxysilane, 50 parts methyltrimethoxysilane, 0.08 parts hydrochloric acid, and 50 parts nano-silica.

[0082] Ethanol was added to a dispersion tank at 30°C and stirred at 80 rpm. Hydrochloric acid was added and stirred for 10 min until homogeneous. Methyltrimethoxysilane was slowly added at 30 L / h and stirred until homogeneous. γ-aminopropyltriethoxysilane was slowly added at 30 L / h and stirred until homogeneous. Diisopropyl di(triethanolamine)titanate was slowly added at 30 L / h and stirred until homogeneous. The temperature was raised to 38°C and reacted for 12 h. The temperature was lowered to 30°C, and sodium nitrite, propylene glycol, and nano-silica were added sequentially and stirred for 30 min. Finally, water was added and dispersed until homogeneous to obtain the epoxy coating maintenance agent.

[0083] Comparative Example 3 (without activator)

[0084] Weigh out the following components by weight: 1200 parts water, 80 parts diisopropyl di(triethanolamine)titanate, 25 parts hexadecylamine, 25 parts diethylaminoethanol, 25 parts imidazoline quaternary ammonium salt, 400 parts ethanol, 50 parts γ-aminopropyltriethoxysilane, 15 parts methyltrimethoxysilane, 0.1 parts hydrochloric acid, and 75 parts nano-silica.

[0085] Ethanol was added to a dispersion tank at 28°C and stirred at 70 rpm. Hydrochloric acid was added and stirred for 7 min until homogeneous. Methyltrimethoxysilane was slowly added at a rate of 25 L / h and stirred until homogeneous. γ-aminopropyltriethoxysilane was slowly added at a rate of 25 L / h and stirred until homogeneous. Diisopropyl di(triethanolamine)titanate was slowly added at a rate of 25 L / h and stirred until homogeneous. The temperature was raised to 38°C and reacted for 9 h. The temperature was then lowered to 28°C, and hexadecylamine, diethylaminoethanol, imidazoline quaternary ammonium salt, and nano-silica were added sequentially and stirred for 30 min. Finally, water was added and dispersed until homogeneous to obtain the epoxy coating maintenance agent.

[0086] Comparative Example 4 (Reaction temperature too high)

[0087] Weigh out the following components by weight: 1200 parts water, 50 parts diisopropyl di(triethanolamine)titanate, 25 parts diethylaminoethanol, 25 parts imidazoline quaternary ammonium salt, 15 parts N-methylpyrrolidone, 25 parts dimethyl sulfoxide, 400 parts ethanol, 50 parts γ-aminopropyltriethoxysilane, 15 parts methyltrimethoxysilane, 0.1 parts hydrochloric acid, and 75 parts nano-silica.

[0088] Ethanol was added to a dispersion tank at 50°C and stirred at 50 rpm. Hydrochloric acid was added and stirred for 6 minutes until homogeneous. Methyltrimethoxysilane was slowly added at a rate of 27 L / h and stirred until homogeneous. γ-aminopropyltriethoxysilane was slowly added at a rate of 27 L / h and stirred until homogeneous. Diisopropyl di(triethanolamine)titanate was slowly added at a rate of 27 L / h and stirred until homogeneous. The temperature was raised to 60°C and reacted for 8 hours. The temperature was then lowered to 25°C, and hexadecylamine, diethylaminoethanol, N-methylpyrrolidone, dimethyl sulfoxide, and nano-silica were added sequentially and stirred for 30 minutes. Finally, water was added and dispersed until homogeneous to obtain the epoxy coating maintenance agent.

[0089] Comparative Example 5 (compared to Example 6, without the addition of methyltrimethoxysilane)

[0090] Weigh out the following components by weight: 1200 parts water, 75 parts diisopropyl di(triethanolamine)titanate, 75 parts diethylaminoethanol, 25 parts imidazoline quaternary ammonium salt, 25 parts dimethyl sulfoxide, 75 parts propylene glycol, 400 parts ethanol, 30 parts γ-aminopropyltriethoxysilane, 0.08 parts hydrochloric acid, and 25 parts nano-silica.

[0091] Ethanol was added to a dispersion tank at 25°C and stirred at 80 rpm. Hydrochloric acid was added and stirred for 5 min until homogeneous. γ-aminopropyltriethoxysilane was slowly added at a rate of 30 L / h and stirred until homogeneous. Diisopropyl di(triethanolamine)titanate was slowly added at a rate of 230 L / h and stirred until homogeneous. The temperature was raised to 35°C and reacted for 12 h. The temperature was lowered to 25°C and diethylaminoethyl, imidazoline quaternary ammonium salt, dimethyl sulfoxide, propylene glycol, and nano silica were added sequentially and stirred for 30 min. Finally, water was added and dispersed until homogeneous to obtain the epoxy coating maintenance agent.

[0092] Comparative Example 6 (without the addition of γ-aminopropyltriethoxysilane compared to Example 6)

[0093] Weigh out the following components by weight: 1200 parts water, 75 parts diisopropyl di(triethanolamine)titanate, 75 parts diethylaminoethanol, 25 parts imidazoline quaternary ammonium salt, 25 parts dimethyl sulfoxide, 75 parts propylene glycol, 400 parts ethanol, 30 parts methyltrimethoxysilane, 0.08 parts hydrochloric acid, and 25 parts nano silica.

[0094] Ethanol was added to a dispersion tank at 25°C and stirred at 80 rpm. Hydrochloric acid was added and stirred for 5 min until homogeneous. Methyltrimethoxysilane was slowly added at 30 L / h and stirred until homogeneous. Diisopropyl di(triethanolamine)titanate was slowly added at 30 L / h and stirred until homogeneous. The temperature was raised to 35°C and reacted for 12 h. The temperature was lowered to 25°C and diethylaminoethyl, imidazoline quaternary ammonium salt, dimethyl sulfoxide, propylene glycol, and nano silica were added sequentially and stirred for 30 min. Finally, water was added and dispersed until homogeneous to obtain the epoxy coating maintenance agent.

[0095] Table 2 Raw material ratios for Comparative Examples 1-6

[0096]

[0097] Performance test examples

[0098] A sample was prepared according to the C4.06 matching system in "Table C.4—Coating systems for carbon steel at corrosion level C4" of ISO 12944-5-2017, "Protective coating systems for steel structures—Part 5: Protective coating systems" (ISO 12944-5-2017). The steel plate material and dimensions met the requirements of "General methods for preparing paint films" (GB 1727-92). The primer was epoxy iron oxide red primer, the intermediate coat was epoxy micaceous iron oxide intermediate coat, and the topcoat was epoxy topcoat, with a total thickness of 240 μm. After the sample was prepared, it was artificially accelerated aging according to ISO 12944-9-2017, "Protective coating systems for steel structures—Part 9: Protective coating systems for marine structures and related structures—Laboratory performance testing methods" (ISO 12944-9-2017), undergoing 1680 hours of cyclic aging (72 hours). UV / condensation, 72h salt spray test, 24h low temperature (-20±2)℃ exposure constitute one cycle, for a total of 10 cycles). After aging, the sample (set as the original sample) is coated with epoxy coating maintenance agent, and then a 720℃ salt spray test is carried out according to "Corrosion protection of steel structures by paint and varnish protective coating systems - Part 6: Laboratory performance test methods" (ISO 12944-6-2017).

[0099] During the experiment, the original sample without epoxy coating maintenance agent was used as the control group. It was then subjected to salt spray test together with the sample coated with the epoxy coating maintenance agent prepared in Examples 1-8 and the comparative sample coated with the epoxy coating maintenance agent prepared in Comparative Examples 1-6. Performance tests were then conducted. The test items were carried out in accordance with the items specified in ISO 12944-6-2017 "6.4 Evaluation after artificial aging test for a specified time". The test results are shown in Table 3.

[0100] Table 3 Performance test results for each group

[0101]

[0102] As shown in Table 3, compared with the original samples in the control group that were not coated with epoxy coating protectant, the overall performance of the epoxy coating was significantly improved after applying epoxy coating protectant in Examples 1-8. The anti-foaming performance was improved by 2 levels, the anti-corrosion performance was improved by 2 levels, the rust at the scribing point was significantly narrowed by 0.3-0.4 mm, and the adhesion was significantly improved (for example, the adhesion in Example 6 reached 13.5 MPa). This indicates that the epoxy coating protectant has a significant maintenance and repair effect on the aged epoxy coating and can extend the service life of the epoxy coating.

[0103] The performance test results of Comparative Example 1 show that, compared with Examples 1-8, when the compatibilizer is insufficient, the wettability of the defects decreases, the penetration of the curing agent and the sealing effect on the defects weaken, and during the artificial aging process, moisture and corrosive media are more likely to invade along the incompletely sealed defects and accumulate at the interface, resulting in a small amount of bubbling. At the same time, the adhesion is also significantly reduced.

[0104] The performance test results of Comparative Example 2 show that, compared with Examples 1-8, when the inorganic corrosion inhibitor sodium nitrite is used to replace the organic corrosion inhibitor, more obvious blistering and rusting occur. At the same time, the rust width at the scribing is relatively wide, and the adhesion decreases after aging. This is because the inorganic corrosion inhibitor dissolves in the salt spray droplets on the coating surface and cannot fully penetrate into the surface and interior of the coating defects. Furthermore, it cannot form a stable and effective corrosion inhibitor film on the substrate surface, resulting in a weakening of the synergistic effect of the components and an inability to effectively maintain the coating.

[0105] The performance test results of Comparative Example 3 show that, compared with Examples 1-8, when the amount of activator added is insufficient or absent, obvious floating rust appears after artificial aging. This is because the epoxy coating surface and defects cannot be effectively activated, the wetting, penetration and anchoring effect of the maintenance agent is significantly reduced, the silane hybrid network and nano silica cannot seal and repair the micro defects of the coating, and the organic corrosion inhibitor cannot penetrate to the substrate surface to form a protective film. Therefore, the epoxy coating cannot be fully maintained, and the repair and maintenance effect of micro defects is weakened.

[0106] The performance test results of Comparative Example 4 show that, compared with Examples 1-8, when the preparation conditions of the epoxy coating maintenance agent are changed (such as increasing the reaction temperature), it will lead to problems such as excessive reaction, excessive cross-linking, and excessively large particles. As a result, the epoxy coating maintenance agent system becomes slightly turbid, and the penetration and sealing effect on nano-sized defects is significantly reduced. Specifically, the coating exhibits problems such as blistering, corrosion, and significantly reduced adhesion after artificial aging.

[0107] The performance test results of Comparative Examples 5 and 6 show that, compared to Example 6, when methyltrimethoxysilane or γ-aminopropyltriethoxysilane was not added, slight blistering and significant corrosion occurred after artificial aging, the corrosion width at the scribing points increased, and the adhesion was significantly reduced. This is because methyltrimethoxysilane and γ-aminopropyltriethoxysilane are among the core monomers for constructing the silane hybrid network. Their synergistic effect forms strongly anchored, robust, and dense "organic-inorganic hybrid siloxane" active particles on the surface of the old coating and within micro-defects. While bridging micro-defects in the coating, they also effectively block moisture penetration. The absence of either one prevents the maintenance agent from forming a continuous and dense siloxane cross-linked structure on the coating defects and substrate surface, reducing the bonding strength with the coating and failing to effectively block moisture penetration, thus failing to fully exert the maintenance effect on the epoxy coating.

[0108] In summary, the epoxy coating maintenance agent of this invention, when sprayed onto the surface of the epoxy coating, can penetrate deep into the coating defects, creating a robust and dense "organic-inorganic hybrid silicon-oxygen network" on and inside the coating defects, thereby achieving deep repair and long-term maintenance of the epoxy coating.

[0109] The embodiments described above are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

Claims

1. An epoxy coating maintenance agent, characterized in that, The maintenance agent comprises, by weight parts: 1200 parts water, 15-100 parts compatibilizer, 15-100 parts organic corrosion inhibitor, 15-100 parts coating activator, 400 parts ethanol, 15-100 parts γ-aminopropyltriethoxysilane, 15-100 parts methyltrimethoxysilane, 0.01-0.2 parts catalyst, and 15-100 parts nano silica. The compatibilizer includes diisopropyl di(triethanolamine)titanate, and the coating activator includes one or more of N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), and propylene glycol.

2. The epoxy coating maintenance agent according to claim 1, characterized in that: The organic corrosion inhibitor includes one or more of hexadecylamine, diethylaminoethanol, and imidazoline quaternary ammonium salt.

3. The epoxy coating maintenance agent according to claim 1, characterized in that: The catalyst includes hydrochloric acid.

4. The method for preparing the epoxy coating maintenance agent according to any one of claims 1-3, characterized in that, The preparation method includes the following steps: S1. Stir the ethanol and catalyst evenly to obtain a mixed solution; S2. Add methyltrimethoxysilane, γ-aminopropyltriethoxysilane and compatibilizer sequentially to the mixed solution obtained in step S1, heat the reaction and then cool down to obtain the reaction product. S3. Add organic corrosion inhibitor, coating activator and nano silica to the reaction product obtained in step S2 in sequence, stir evenly, then add water and stir evenly to obtain the epoxy coating maintenance agent.

5. The preparation method according to claim 4, characterized in that, In step S2, the reaction temperature is 35~38℃, the reaction time is 8~12h, and the temperature after cooling is 25~30℃.

6. A method for maintaining an epoxy coating, comprising applying an epoxy coating maintenance agent as described in any one of claims 1-3, wherein the method includes the step of applying the epoxy coating maintenance agent to the surface of the epoxy coating.

7. The use of the epoxy coating maintenance agent according to any one of claims 1-3 in improving the durability of epoxy coatings.

8. The application according to claim 7, characterized in that: The application includes at least one of the following: (1) Application in improving the anti-bubbling properties of epoxy coatings; (2) Application in improving the corrosion resistance of epoxy coatings; (4) Application in improving the crack resistance of epoxy coatings; (5) Application in improving the anti-peeling properties of epoxy coatings; (6) Application in improving the corrosion resistance of epoxy coatings; (7) Application in improving the adhesion of epoxy coatings.

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