A corrosion resistant coating for electrical steel parts and a method for producing the same

Abstract

The present application relates to the field of coating, disclose a kind of electric power iron accessory corrosion-resistant coating and its preparation method, the coating includes: water-based epoxy resin, modified composite filler, spherical zinc powder, curing agent, auxiliary agent;Modified composite filler is made by grafting amino on the surface of composite filler by m-phenylenediamine, and loading benzotriazole on the surface of polyaniline modified composite filler;Composite filler is made by composite by electrostatic interaction using amino-nano titanium dioxide and graphene oxide;Curing agent is made by silicon-hydrogen addition after the reaction of 4-propyleneoxy-2-hydroxybenzophenone and 4,4'-diacyl dichloride diphenyl ether with silicon-containing curing intermediate;Silicon-containing curing intermediate is made by substitution after the addition of DOPO and thiourea with 2-chloro-5-(prop-1-en-2-yl) thiophene and reaction with 1,1,3,3-tetramethyldisiloxane, the coating prepared by the present application has good mechanical strength, salt fog resistance, moisture resistance, ultraviolet aging resistance and flame retardant effect.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, specifically relating to a corrosion-resistant coating for power railway accessories and its preparation method. Background Technology

[0002] Power line accessories are an indispensable and important component of power systems. They are mainly used to support, fix, and connect power lines and cables, ensuring the stability and safety of power transmission. In protective coating systems, zinc-rich coatings are widely used in power line accessories due to their unique "sacrificial anode protecting cathode" electrochemical protection mechanism, where zinc powder in the coating preferentially undergoes a corrosion reaction to protect the base metal. However, long-term application practice has revealed significant limitations of zinc-rich coatings: to ensure that zinc powder can form a continuous conductive path and play an effective protective role, its addition amount in the coating is relatively high, resulting in high coating costs. In addition, to ensure long-term corrosion protection, the coating thickness needs to be increased, but this can easily lead to cracking and other problems.

[0003] Epoxy resin is a thermosetting polymer with two or more epoxy groups. It typically relies on its own epoxy groups to undergo cross-linking reactions with various curing agents to form a network structure. It also possesses excellent mechanical, thermal, and anti-corrosion properties, making it widely used in corrosion-resistant coatings. Waterborne epoxy anti-corrosion coatings have gained significant attention compared to solvent-based epoxy coatings due to their environmental friendliness. However, during the cross-linking reaction with curing agents, micropores easily form on the epoxy resin coating surface. These pores severely affect the epoxy resin's ability to block media, leading to corrosion. Therefore, inorganic nanofillers are often added to fill the epoxy resin and improve its performance. However, inorganic nanofillers are often difficult to disperse in the base material, thus affecting mechanical properties. Furthermore, existing epoxy resin coatings have shortcomings in outdoor UV aging resistance and flame retardancy, and their mechanical strength and corrosion resistance need further improvement for wider application. Summary of the Invention

[0004] To address the shortcomings mentioned in the background art, the present invention aims to provide a corrosion-resistant coating for power railway accessories and its preparation method. By adding modified composite fillers and curing agents, the prepared coating has high pencil hardness, good impact resistance, and also possesses good salt spray resistance, damp heat resistance, UV aging resistance, and flame retardant effect.

[0005] The objective of this invention can be achieved through the following technical solutions: A corrosion-resistant coating for power railway accessories comprises the following raw materials in parts by weight: 40-65 parts of water-based epoxy resin, 6-15 parts of modified composite filler, 10-20 parts of spherical zinc powder, 5-12 parts of curing agent, 0.3-0.8 parts of wetting agent, 0.3-0.5 parts of defoamer, 0.2-0.6 parts of leveling agent, and 0.2-0.6 parts of dispersant; The modified composite filler is prepared by grafting m-phenylenediamine onto the surface of the composite filler to form an aminated composite filler, and then by grafting polyaniline onto the surface of the aminated composite filler using an in-situ copolymerization method to prepare a polyaniline-modified composite filler. Subsequently, the corrosion inhibitor benzotriazole is loaded onto the surface of the polyaniline-modified composite filler. The composite filler is prepared by electrostatically combining γ-aminopropyltriethoxysilane-modified aminated nano-titanium dioxide with graphene oxide. The curing agent is prepared by nucleophilic substitution reaction of 4-propenoxy-2-hydroxybenzophenone with 4,4'-diacyl chloride diphenyl ether, followed by hydrosilylation reaction of the resulting double-bonded benzophenone intermediate with a silicon-containing curing intermediate; the silicon-containing curing intermediate is prepared by direct addition reaction of DOPO with thiourea to prepare a mercapto curing intermediate, followed by nucleophilic substitution reaction of 2-chloro-5-(prop-1-en-2-yl)thiophene with the mercapto curing intermediate, and then hydrosilylation reaction of the resulting double-bonded curing intermediate with 1,1,3,3-tetramethyldisiloxane.

[0006] Preferably, the wetting agent is polydimethylsiloxane; the defoamer is fatty alcohol polyoxyethylene ether or alkylphenol polyoxyethylene ether; the leveling agent is sodium polyacrylate; and the dispersant is BYK-190 or BYK-191.

[0007] Preferably, the preparation method of the modified composite filler includes the following steps: A. Take γ-aminopropyltriethoxysilane, ethanol and deionized water into a reactor, stir and mix them, then add nano-titanium dioxide, and stir at 65~70℃ for 1.5~2h. After the reaction is completed, filter, wash and dry to prepare aminated nano-titanium dioxide. B. Take aminated nano-titanium dioxide and ultrasonically disperse it in deionized water, then add the suspension of graphene oxide and deionized water, and stir at 55~70℃ for 1.5~2h. After stirring, centrifuge, wash and dry to prepare composite filler. C. Take the composite filler and m-phenylenediamine and ultrasonically disperse them in deionized water, then add sodium nitrite, place in an ice-water bath and stir for 4-8 hours. After the reaction is completed, wash, filter and dry to prepare the aminated composite filler. D. Take the aminated composite filler and aniline and ultrasonically disperse them in deionized water, then slowly add ammonium persulfate, place in an ice-water bath and stir for 4-5 hours. After the reaction is completed, wash, filter and dry to prepare polyaniline modified composite filler. E. Take benzotriazole and deionized water in a reactor and heat to 40~45℃ to obtain benzotriazole aqueous solution. Then, add polyaniline modified composite filler under continuous stirring and apply vacuum for 20~24h using a vacuum pump. After filtration, washing and drying, the modified composite filler is prepared.

[0008] Preferably, in step C, the mass ratio of the composite filler, m-phenylenediamine, and sodium nitrite is 1:0.7~1.1:0.5~0.7.

[0009] Preferably, in step D, the addition ratio of aminated composite filler, aniline and ammonium persulfate is 0.8~1.1g:2~4mL:7~7.5g; and in step E, the addition ratio of benzotriazole, deionized water and polyaniline modified composite filler is 1g:20~30mL:1.2~1.6g.

[0010] Preferably, the method for preparing the curing agent includes the following steps: I. Place DOPO, thiourea and deionized water in a reactor and reflux at 85~95℃ for 4~8h. After the reaction is completed, let it stand for 0.5~1h. The precipitated product is washed and dried to prepare a mercapto-cured intermediate. II. In an argon-purged reactor, the mercapto-cured intermediate was dissolved in 1,3-dimethyl-2-imidazolinone, and potassium carbonate and toluene were added and stirred. The mixture was heated to 155-160°C and the evaporated toluene was collected. After the toluene was removed, the temperature was lowered to 115-120°C, and then a mixed solution of 2-chloro-5-(prop-1-en-2-yl)thiophene and 1,3-dimethyl-2-imidazolinone was added. The reaction was carried out for 10-12 hours. After the reaction was completed, the mixture was poured into ice water and allowed to stand until the product solidified. The product was then filtered, washed, and recrystallized to obtain the double bond-cured intermediate. III. Take the double bond group solidified intermediate, the cassiterite catalyst and toluene in a reactor, heat to 55~65℃, slowly add 1,1,3,3-tetramethyldisiloxane, stir the reaction for 8~12h, remove unreacted material by rotary evaporation after the reaction is completed, and separate by column chromatography to prepare the silicon-containing solidified intermediate; IV. Take 4-propenoxy-2-hydroxybenzophenone, tetrahydrofuran and triethylamine in a reactor, introduce nitrogen gas, and add 4,4'-diacyl chloride diphenyl ether when the system temperature reaches 0℃ in an ice-water bath. After reacting for 0.5~1.5h, raise the temperature to room temperature and react for 1.5~2.5h. After the reaction is completed, extract, rotary evaporate and column chromatography are used to separate the intermediates to obtain the double-bonded benzophenone group. V. Take the double-bonded benzophenone intermediate, the silicon-containing curing intermediate, toluene and the cassiterite catalyst into a reactor, stir and heat to 55~65℃ and react for 10~12h. After the reaction is completed, remove the unreacted material by rotary evaporation and separate by column chromatography to prepare the curing agent.

[0011] Preferably, in step I, the molar ratio of DOPO to thiourea is 1:1 to 1.2; and in step II, the molar ratio of the mercapto-cured intermediate to 2-chloro-5-(prop-1-en-2-yl)thiophene is 1 to 1.3:1.

[0012] Preferably, in step III, the molar ratio of the double-bonded curing intermediate to 1,1,3,3-tetramethyldisiloxane is 1 to 1.1:1.

[0013] Preferably, in step IV, the molar ratio of 4-propenoxy-2-hydroxybenzophenone and 4,4'-diacyl chloride diphenyl ether is 2~2.2:1; and in step V, the molar ratio of the double-bonded benzophenone intermediate and the silicon-containing curing intermediate is 1:2~2.2.

[0014] The preparation method of the corrosion-resistant coating for power railway accessories as described above includes the following steps: weighing each raw material according to the weight parts, mixing water-based epoxy resin and dispersant evenly, then adding modified composite filler, spherical zinc powder, wetting agent and leveling agent and stirring evenly, then adding curing agent and defoamer and stirring evenly to prepare the corrosion-resistant coating for power railway accessories.

[0015] The beneficial effects of this invention are: This invention utilizes γ-aminopropyltriethoxysilane-modified aminated nano-titanium dioxide and carboxyl groups in graphene oxide structure to electrostatically composite, encapsulating graphene oxide on the surface of the aminated nano-titanium dioxide to prepare a core-shell structured composite filler. Then, amino groups are grafted onto the surface of the composite filler using m-phenylenediamine, and polyaniline is grafted onto the surface of the aminated composite filler using an in-situ copolymerization method. Subsequently, the corrosion inhibitor benzotriazole is loaded onto the surface of the polyaniline-modified composite filler to prepare a modified composite filler, reducing the amount of zinc powder required. The nano-titanium dioxide possesses photocatalytic antibacterial and ultraviolet shielding effects, while graphene oxide exhibits excellent mechanical reinforcement and barrier properties. Encapsulating graphene oxide on the surface of the amino-modified nano-titanium dioxide solves the dispersion problem of graphene oxide in the coating and provides good mechanical properties. Furthermore, the modified composite filler prepared by this invention simultaneously possesses the shielding effect of graphene oxide, the passivation effect of polyaniline, and the corrosion inhibition effect of benzotriazole, exhibiting excellent anti-corrosion performance.

[0016] This invention utilizes the direct addition reaction between the PH bond in DOPO and the C=S bond in the thiourea structure to prepare a thiol-cured intermediate. Then, a nucleophilic substitution reaction is performed between 2-chloro-5-(prop-1-en-2-yl)thiophene and the thiol-cured intermediate to prepare a double-bonded cured intermediate. Furthermore, a hydrosilylation reaction is conducted between the double-bonded cured intermediate and a single-terminal silane-hydrogen bond in 1,1,3,3-tetramethyldisiloxane to prepare a silicon-containing cured intermediate. Simultaneously, this invention utilizes the nucleophilic substitution reaction between 4-propenoxy-2-hydroxybenzophenone and 4,4'-diacylchlorodiphenyl ether to prepare... A benzophenone-based intermediate is double-bonded, and then the double-bonded benzophenone-based intermediate undergoes a hydrosilylation reaction with the remaining silane bonds in a silicon-containing curing intermediate to prepare a curing agent containing four amino groups. This curing agent participates in the epoxy resin curing reaction to form a highly cross-linked three-dimensional network structure, enhancing the density of the coating, and introducing phosphorus-silicon-sulfur elements for synergistic flame retardancy. At the same time, the introduction of benzophenone structure and thioester groups into the curing agent structure can act as a UV absorber to increase the UV resistance of the coating. In addition, the introduction of silicon-oxygen bonds with high heat resistance and water resistance is beneficial to enhancing the coating's resistance to damp heat. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1: A method for preparing a modified composite filler includes the following steps: A. Take 20 mL of γ-aminopropyltriethoxysilane, 120 mL of ethanol and 60 mL of deionized water into a reactor, stir and mix, then add 8 g of nano titanium dioxide, place at 70 °C and stir for 1.5 h. After the reaction is completed, filter, wash and dry to prepare aminated nano titanium dioxide. B. Take 1g of aminated nano-titanium dioxide and ultrasonically disperse it in 50mL of deionized water. Then add 0.2g of graphene oxide and 25mL of deionized water suspension, and stir at 60℃ for 2h. After stirring, centrifuge, wash and dry to prepare composite filler. C. Take 1g of composite filler and 0.8g of m-phenylenediamine and ultrasonically disperse them in 250mL of deionized water. Then add 0.6g of sodium nitrite and stir in an ice-water bath for 6h. After the reaction is completed, wash, filter and dry to prepare the aminated composite filler. D. Take 1g of aminated composite filler and 3mL of aniline and ultrasonically disperse them in 250mL of deionized water. Then slowly add 7.2g of ammonium persulfate and stir in an ice-water bath for 5h. After the reaction is completed, wash, filter and dry to prepare polyaniline modified composite filler. E. Take 4g of benzotriazole and 100mL of deionized water in a reactor, heat to 40℃ to obtain an aqueous solution of benzotriazole, then add 6g of polyaniline-modified composite filler under continuous stirring, and apply vacuum for 24h using a vacuum pump. After filtration, washing and drying, the modified composite filler is prepared.

[0019] Example 2: A method for preparing a curing agent includes the following steps: I. Take 21.6g DOPO, 7.6g thiourea and 70mL deionized water into a reactor, place it at 95℃ and reflux for 8h, let it stand for 0.5h after the reaction is completed, wash and dry the precipitated product to prepare the mercapto-cured intermediate; II. In an argon-purged reactor, 64.3 g of the mercapto-cured intermediate was dissolved in 180 mL of 1,3-dimethyl-2-imidazolinone, and 32 g of potassium carbonate and 150 mL of toluene were added and stirred. The mixture was heated to 160 °C and the evaporated toluene was collected. After the toluene was removed, the temperature was lowered to 120 °C, and then a mixed solution of 28.6 g of 2-chloro-5-(prop-1-en-2-yl)thiophene and 60 mL of 1,3-dimethyl-2-imidazolinone was added. The mixture was reacted for 12 h. After the reaction was completed, the mixture was poured into 1 L of ice water and allowed to stand until the product solidified. The product was then filtered, washed, and recrystallized to obtain the double bond-cured intermediate. III. Take 20.8 g of double bond-based solidified intermediate, 0.4 g of caster catalyst (Pt 2Wt%, xylene as solvent) and 100 mL of toluene in a reactor, heat to 60 °C, slowly add 6.7 g of 1,1,3,3-tetramethyldisiloxane, stir and react for 10 h, remove unreacted material by rotary evaporation after the reaction is completed, and separate by column chromatography to prepare silicon-containing solidified intermediate; IV. Take 12.7g of 4-propenoxy-2-hydroxybenzophenone, 80mL of tetrahydrofuran and 5.1g of triethylamine into a reactor, purge with nitrogen, and heat in an ice-water bath until the system temperature reaches 0℃. Then add 7.4g of 4,4'-diacyl chloride diphenyl ether and react for 1h. Then raise the temperature to room temperature and react for 2h. After the reaction is completed, extract, rotary evaporate and column chromatography are used to separate the intermediates to obtain the double-bonded benzophenone group. V. Take 14.6g of double-bonded benzophenone intermediate, 21.9g of silicon-containing curing intermediate, 120mL of toluene and 0.6g of caster catalyst (Pt 2Wt%, xylene as solvent) in a reactor, stir and heat to 60℃ and react for 12h. After the reaction is completed, remove unreacted material by rotary evaporation and separate by column chromatography to prepare curing agent.

[0020] Example 3 A corrosion-resistant coating for power railway accessories, comprising the following raw materials in parts by weight: 44 parts of water-based epoxy resin, 6.3 parts of the modified composite filler prepared in Example 1, 12 parts of spherical zinc powder, 5.5 parts of the curing agent prepared in Example 2, 0.3 parts of wetting agent polydimethylsiloxane, 0.3 parts of defoamer fatty alcohol polyoxyethylene ether, 0.2 parts of leveling agent sodium polyacrylate, and 0.2 parts of dispersant BYK-190.

[0021] The preparation method of the above-mentioned corrosion-resistant coating for power railway accessories includes the following steps: weighing each raw material according to the weight parts, mixing water-based epoxy resin and dispersant evenly, then adding modified composite filler, spherical zinc powder, wetting agent and leveling agent and stirring evenly, then adding curing agent and defoamer and stirring evenly to prepare the corrosion-resistant coating for power railway accessories.

[0022] Example 4 A corrosion-resistant coating for power railway accessories, comprising the following raw materials in parts by weight: 56 parts of water-based epoxy resin, 10.2 parts of modified composite filler prepared in Example 1, 16.1 parts of spherical zinc powder, 8.7 parts of curing agent prepared in Example 2, 0.5 parts of wetting agent polydimethylsiloxane, 0.4 parts of defoamer alkylphenol polyoxyethylene ether, 0.4 parts of leveling agent sodium polyacrylate, and 0.3 parts of dispersant BYK-191.

[0023] The preparation method of the corrosion-resistant coating for the above-mentioned power iron accessories is the same as that in Example 3.

[0024] Example 5 A corrosion-resistant coating for power railway accessories, comprising the following raw materials in parts by weight: 63 parts of water-based epoxy resin, 14.5 parts of modified composite filler prepared in Example 1, 19.8 parts of spherical zinc powder, 11.4 parts of curing agent prepared in Example 2, 0.6 parts of wetting agent polydimethylsiloxane, 0.5 parts of defoamer fatty alcohol polyoxyethylene ether, 0.5 parts of leveling agent sodium polyacrylate, and 0.5 parts of dispersant BYK-190.

[0025] The preparation method of the corrosion-resistant coating for the above-mentioned power iron accessories is the same as that in Example 3.

[0026] Comparative Example 1: A corrosion-resistant coating for power railway accessories, comprising the following raw materials in parts by weight: 63 parts of waterborne epoxy resin, 14.5 parts of polyaniline-modified composite filler prepared in Example 1, 19.8 parts of spherical zinc powder, 11.4 parts of curing agent prepared in Example 2, 0.6 parts of wetting agent polydimethylsiloxane, 0.5 parts of defoamer fatty alcohol polyoxyethylene ether, 0.5 parts of leveling agent sodium polyacrylate, and 0.5 parts of dispersant BYK-190.

[0027] The preparation method of the corrosion-resistant coating for the above-mentioned power iron accessories is the same as that in Example 3.

[0028] Comparative Example 2: A corrosion-resistant coating for power railway accessories, comprising the following raw materials in parts by weight: 63 parts of waterborne epoxy resin, 14.5 parts of the composite filler prepared in Example 1, 19.8 parts of spherical zinc powder, 11.4 parts of the curing agent prepared in Example 2, 0.6 parts of wetting agent polydimethylsiloxane, 0.5 parts of defoamer fatty alcohol polyoxyethylene ether, 0.5 parts of leveling agent sodium polyacrylate, and 0.5 parts of dispersant BYK-190.

[0029] The preparation method of the corrosion-resistant coating for the above-mentioned power iron accessories is the same as that in Example 3.

[0030] Comparative Example 3: A corrosion-resistant coating for power railway accessories, comprising the following raw materials in parts by weight: 63 parts of waterborne epoxy resin, 12.1 parts of nano-titanium dioxide, 4 parts of graphene oxide (Example 2), 19.8 parts of spherical zinc powder, 11.4 parts of curing agent prepared in Example 2, 0.6 parts of wetting agent polydimethylsiloxane, 0.5 parts of defoamer fatty alcohol polyoxyethylene ether, 0.5 parts of leveling agent sodium polyacrylate, and 0.5 parts of dispersant BYK-190.

[0031] The preparation method of the corrosion-resistant coating for the above-mentioned power iron accessories is the same as that in Example 3.

[0032] Comparative Example 4: A corrosion-resistant coating for power railway accessories, comprising the following raw materials in parts by weight: 63 parts of waterborne epoxy resin, 14.5 parts of the modified composite filler prepared in Example 1, 19.8 parts of spherical zinc powder, 11.4 parts of the silicon-containing curing intermediate prepared in Example 2, 0.6 parts of wetting agent polydimethylsiloxane, 0.5 parts of defoamer fatty alcohol polyoxyethylene ether, 0.5 parts of leveling agent sodium polyacrylate, and 0.5 parts of dispersant BYK-190.

[0033] The preparation method of the corrosion-resistant coating for the above-mentioned power iron accessories is the same as that in Example 3.

[0034] Comparative Example 5: A corrosion-resistant coating for power railway accessories, comprising the following raw materials in parts by weight: 63 parts of waterborne epoxy resin, 14.5 parts of the modified composite filler prepared in Example 1, 19.8 parts of spherical zinc powder, 11.4 parts of m-phenylenediamine, 0.6 parts of wetting agent polydimethylsiloxane, 0.5 parts of defoamer fatty alcohol polyoxyethylene ether, 0.5 parts of leveling agent sodium polyacrylate, and 0.5 parts of dispersant BYK-190.

[0035] The preparation method of the corrosion-resistant coating for the above-mentioned power iron accessories is the same as that in Example 3.

[0036] Performance testing The corrosion-resistant coatings prepared in Examples 3-5 and Comparative Examples 1-5 were subjected to performance tests. The test samples were 3mm thick sandblasted steel plates that had undergone pretreatment, with the film thickness controlled between 200 and 240 μm. After the test samples were coated, they were cured at 23℃ and (50±5)% relative humidity for 7 days. The impact resistance of the coatings was tested according to GB / T 1732-2020; the pencil hardness of the coatings was tested according to GB / T 6739-2022; the salt spray resistance of the coatings was tested according to GB / T 10125-2021; and the damp heat resistance of the coatings was tested according to GB / T 1740-2007. The UV aging resistance of the coatings was tested using a QUV ultraviolet aging test chamber, and the aging rating of the coatings was based on GB / T From 1766 to 2008, the gloss of the coating was measured using a gloss meter. The gloss loss rate was evaluated as grade 0 to 5, where grade 0 had a gloss loss rate of 1 to 3%, grade 1 had a gloss loss rate of 4 to 15%, grade 2 had a gloss loss rate of 16 to 30%, grade 3 had a gloss loss rate of 31 to 50%, grade 4 had a gloss loss rate of 51 to 80%, and grade 5 had a gloss loss rate of >80%. The data results are shown in Table 1.

[0037] Table 1 Sample performance test results As shown in Table 1, the coated pencils prepared in Examples 3-5 of this invention have high hardness, good impact resistance, and also possess good salt spray resistance, damp heat resistance, UV aging resistance, and flame retardant effect. In Comparative Example 1, the modified composite filler was replaced with an equal amount of polyaniline-modified composite filler. In Comparative Example 2, no modification treatment was performed on the composite filler. The measured salt spray resistance in Comparative Examples 1-2 was lower than that in Examples 3-5, with Comparative Example 2 showing a more significant decrease. This is because the passivation effect of polyaniline and the corrosion inhibition effect of benzotriazole can synergistically exert excellent anti-corrosion performance. In Comparative Example 3, nano-titanium dioxide and graphene oxide were simply mixed. The measured pencil hardness, impact strength, and salt spray resistance were significantly lower than those in Examples 3-5. This is because the agglomeration of nanoparticles leads to a decrease in mechanical properties. Furthermore, the core-shell structure of the composite filler is beneficial for absorbing and buffering energy, thereby improving the impact resistance of the coating. Additionally, the poor dispersibility of graphene oxide and the lack of... The passivation effect of polyaniline and the corrosion inhibition effect of benzotriazole significantly reduced the anti-corrosion performance. In Comparative Example 4, the curing agent was replaced with an equal amount of silicon-containing curing intermediate, and in Comparative Example 5, the curing agent was replaced with an equal amount of m-phenylenediamine. The measured gloss loss rate of Comparative Examples 4-5 was higher than that of Examples 3-5, and the measured gloss loss rate of Comparative Example 5 was slightly higher than that of Comparative Example 4. This is because the benzophenone structure and thioester group introduced into the curing agent structure can improve the UV aging resistance of the coating to a certain extent. In addition, the measured damp heat resistance and limiting oxygen index of Comparative Example 5 were lower than those of Examples 3-5. This is because the introduction of high heat resistance and water resistance silicon-oxygen bonds is beneficial to improving the damp heat resistance of the coating. At the same time, the lack of phosphorus-silicon-sulfur synergistic flame retardant elements led to a decrease in flame retardant performance.

[0038] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0039] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A corrosion-resistant coating for power railway accessories, characterized in that, The raw materials include the following parts by weight: 40-65 parts of waterborne epoxy resin, 6-15 parts of modified composite filler, 10-20 parts of spherical zinc powder, 5-12 parts of curing agent, 0.3-0.8 parts of wetting agent, 0.3-0.5 parts of defoamer, 0.2-0.6 parts of leveling agent, and 0.2-0.6 parts of dispersant; The preparation method of the modified composite filler includes the following steps: A. Take γ-aminopropyltriethoxysilane, ethanol and deionized water into a reactor, stir and mix them, then add nano-titanium dioxide, and stir at 65~70℃ for 1.5~2h. After the reaction is completed, filter, wash and dry to prepare aminated nano-titanium dioxide. B. Take aminated nano-titanium dioxide and ultrasonically disperse it in deionized water, then add the suspension of graphene oxide and deionized water, and stir at 55~70℃ for 1.5~2h. After stirring, centrifuge, wash and dry to prepare composite filler. C. Take the composite filler and m-phenylenediamine and ultrasonically disperse them in deionized water, then add sodium nitrite, place in an ice-water bath and stir for 4-8 hours. After the reaction is completed, wash, filter and dry to prepare the aminated composite filler. D. Take the aminated composite filler and aniline and ultrasonically disperse them in deionized water, then slowly add ammonium persulfate, place in an ice-water bath and stir for 4-5 hours. After the reaction is completed, wash, filter and dry to prepare polyaniline modified composite filler. E. Take benzotriazole and deionized water in a reactor and heat to 40~45℃ to obtain benzotriazole aqueous solution. Then, add polyaniline modified composite filler under continuous stirring and apply vacuum for 20~24h using a vacuum pump. After filtration, washing and drying, the modified composite filler is prepared. The preparation method of the curing agent includes the following steps: I. Place DOPO, thiourea and deionized water in a reactor and reflux at 85~95℃ for 4~8h. After the reaction is completed, let it stand for 0.5~1h. The precipitated product is washed and dried to prepare a mercapto-cured intermediate. II. In an argon-purged reactor, the mercapto-cured intermediate was dissolved in 1,3-dimethyl-2-imidazolinone, and potassium carbonate and toluene were added and stirred. The mixture was heated to 155-160°C and the evaporated toluene was collected. After the toluene was removed, the temperature was lowered to 115-120°C, and then a mixed solution of 2-chloro-5-(prop-1-en-2-yl)thiophene and 1,3-dimethyl-2-imidazolinone was added. The reaction was carried out for 10-12 hours. After the reaction was completed, the mixture was poured into ice water and allowed to stand until the product solidified. The product was then filtered, washed, and recrystallized to obtain the double bond-cured intermediate. III. Take the double bond group solidified intermediate, the cassiterite catalyst and toluene in a reactor, heat to 55~65℃, slowly add 1,1,3,3-tetramethyldisiloxane, stir the reaction for 8~12h, remove unreacted material by rotary evaporation after the reaction is completed, and separate by column chromatography to prepare the silicon-containing solidified intermediate; IV. Take 4-propenoxy-2-hydroxybenzophenone, tetrahydrofuran and triethylamine in a reactor, introduce nitrogen gas, and add 4,4'-diacyl chloride diphenyl ether when the system temperature reaches 0℃ in an ice-water bath. After reacting for 0.5~1.5h, raise the temperature to room temperature and react for 1.5~2.5h. After the reaction is completed, extract, rotary evaporate and column chromatography are used to separate the intermediates to obtain the double-bonded benzophenone group. V. Take the double-bonded benzophenone intermediate, the silicon-containing curing intermediate, toluene and the cassiterite catalyst into a reactor, stir and heat to 55~65℃ and react for 10~12h. After the reaction is completed, remove the unreacted material by rotary evaporation and separate by column chromatography to prepare the curing agent.

2. The corrosion-resistant coating for power railway accessories according to claim 1, characterized in that, The wetting agent is polydimethylsiloxane; the defoamer is fatty alcohol polyoxyethylene ether or alkylphenol polyoxyethylene ether; the leveling agent is sodium polyacrylate; and the dispersant is BYK-190 or BYK-191.

3. The corrosion-resistant coating for power railway accessories according to claim 1, characterized in that, In step C, the mass ratio of the composite filler, m-phenylenediamine, and sodium nitrite is 1:0.7~1.1:0.5~0.

7.

4. The corrosion-resistant coating for power railway accessories according to claim 1, characterized in that, In step D, the addition ratio of aminated composite filler, aniline and ammonium persulfate is 0.8~1.1g: 2~4mL: 7~7.5g; in step E, the addition ratio of benzotriazole, deionized water and polyaniline modified composite filler is 1g: 20~30mL: 1.2~1.6g.

5. The corrosion-resistant coating for power railway accessories according to claim 1, characterized in that, In step I, the molar ratio of DOPO to thiourea is 1:1 to 1.2; in step II, the molar ratio of the mercapto-cured intermediate to 2-chloro-5-(prop-1-en-2-yl)thiophene is 1 to 1.3:

1.

6. The corrosion-resistant coating for power railway accessories according to claim 1, characterized in that, In step III, the molar ratio of the double-bonded curing intermediate to 1,1,3,3-tetramethyldisiloxane is 1~1.1:

1.

7. The corrosion-resistant coating for power railway accessories according to claim 1, characterized in that, In step IV, the molar ratio of 4-propenoxy-2-hydroxybenzophenone to 4,4'-diacyl chloride diphenyl ether is 2~2.2:1; in step V, the molar ratio of the double-bonded benzophenone intermediate to the silicon-containing curing intermediate is 1:2~2.

2.

8. A method for preparing a corrosion-resistant coating for power railway accessories according to any one of claims 1 to 7, characterized in that, The process includes the following steps: weighing each raw material according to the weight proportions, mixing the water-based epoxy resin and dispersant evenly, then adding the modified composite filler, spherical zinc powder, wetting agent and leveling agent and stirring evenly, followed by adding the curing agent and defoamer and stirring evenly to prepare a corrosion-resistant coating for power iron accessories.

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