High-durability metal preservative and preparation method thereof

Abstract

The invention discloses a high-durability metal preservative and a preparation method thereof, and belongs to the technical field of metal material protection. The invention provides a metal preservative taking two brand-new modified compounds as cores. Wherein the bis (gamma-mercaptopropyl) phosphonate modified polysiloxane is prepared by hydrolyzing gamma-mercaptopropyl trimethoxy silane and then reacting the hydrolyzed gamma-mercaptopropyl trimethoxy silane with triethyl phosphite, and the bis (gamma-mercaptopropyl) phosphonate modified polysiloxane contains sulfydryl and phosphonate groups; the 1, 3-bis (2-hydroxyethyl imidazolinone) modified perfluorinated epoxy resin is prepared by esterifying perfluorooctyl epoxy resin and imidazolinone and then introducing a fluorocarbon chain, and contains an imidazolinone ring and the fluorocarbon chain. The preservative further comprises deionized water, nano aluminum oxide, benzotriazole and the like. The preparation method comprises the following steps: refluxing two modified compounds, extracting, performing esterification polymerization and the like. The product realizes long-acting corrosion inhibition through chemical adsorption of sulfydryl, phosphonate groups and metal, chelating of imidazolinone rings and water blocking of fluorocarbon chains, and the protection performance of the metal in a harsh environment is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of metal material protection technology, specifically to a highly durable metal corrosion inhibitor and its preparation method. Background Technology

[0002] Metal corrosion is one of the core challenges facing the industrial sector for a long time, resulting in enormous direct economic losses globally each year due to material failure and equipment damage caused by corrosion. While traditional metal corrosion inhibitors (such as chromates and zinc powder) can inhibit metal oxidation in the short term, they generally suffer from high toxicity and poor environmental friendliness. Some inhibitors, although less toxic (such as zinc phosphate), lack durability and are prone to hydrolysis and flaking in harsh environments such as humidity and salt spray, leading to short protection cycles, frequent maintenance, and significantly increased costs. More importantly, the bonding between traditional corrosion inhibitors and metal surfaces relies heavily on physical adsorption, resulting in weak adhesion that is susceptible to mechanical friction or environmental stress, easily leading to blistering and peeling, thus failing to meet long-term protection requirements.

[0003] In recent years, organic-inorganic hybrid corrosion-resistant materials have become a research hotspot due to their combination of the film-forming flexibility of organic materials and the weather resistance of inorganic materials. These materials attempt to improve corrosion resistance by introducing corrosion-inhibiting groups (such as carboxylic acids and phosphoric acid) or functional fillers (such as nanoparticles). However, existing technologies still face significant bottlenecks: the coordination ability of a single corrosion-inhibiting group with the metal is limited, making it difficult to cope with synergistic corrosion from multiple factors; the chemical bonding force between the film-forming material and the metal interface is insufficient, relying only on physical embedding or simple adsorption, which easily leads to failure due to environmental changes after long-term use; although some materials improve hydrophobicity through fluorocarbon chains, they lack active corrosion inhibition functions and cannot suppress the initiation of localized corrosion, resulting in a significant decline in protective effectiveness over time. These problems limit the application of hybrid materials in harsh environments such as marine and chemical industries.

[0004] To address the aforementioned pain points, this invention proposes a highly durable metal corrosion inhibitor based on a bifunctional organosilicon corrosion inhibitor and a fluorocarbon imidazolinone epoxy resin. By designing two novel modified compounds, bis(γ-mercaptopropyl)phosphonate-modified polysiloxane and 1,3-bis(2-hydroxyethylimidazolinone)-modified perfluoroepoxy resin, strong chemical adsorption and complexation corrosion inhibition functions of the mercapto and phosphonate groups are provided, respectively, along with the chelating sites of the imidazolinone ring and the low surface energy barrier of the fluorocarbon chain. This synergistic approach solves the problems of poor long-term effectiveness and easy failure in complex environments of traditional corrosion inhibitors, significantly improving the protective lifespan of metals in humid and salt spray environments. Summary of the Invention

[0005] The purpose of this invention is to provide a highly durable metal corrosion inhibitor and its preparation method, which solves the technical problems of poor long-term performance and weak bonding force with metal interfaces of existing metal corrosion inhibitors.

[0006] The present invention achieves the above objectives through the following technical solutions: A highly durable metal corrosion inhibitor, comprising the following raw materials in parts by weight: Bis(γ-mercaptopropyl)phosphonate-modified polysiloxane: 150-300 parts by weight; 1,3-Bis(2-hydroxyethylimidazolinone) modified perfluoroepoxy resin: 200-400 parts by weight; Deionized water: 250-450 parts by weight; Nano-alumina: 30-100 parts by weight; Benzotriazole: 5-20 parts by weight; Hydroxypropyl methylcellulose: 5-15 parts by weight; Organosilicon defoamer: 1-5 parts by weight; The preparation method of the bis(γ-mercaptopropyl)phosphonate-modified polysiloxane includes: A1, dissolving γ-mercaptopropyltrimethoxysilane in anhydrous toluene, adding hydrochloric acid, and refluxing at 60-62℃; A2, removing toluene and water by vacuum distillation, transferring the product to a three-necked flask, adding triethyl phosphite and triethylamine, heating to 100-102℃, and finally hydrolyzing to obtain bis(γ-mercaptopropyl)phosphonate-modified polysiloxane; nitrogen gas is continuously introduced during the reaction to isolate moisture, and the crude product is purified by ethyl acetate extraction and column chromatography.

[0007] According to a preferred embodiment of the present invention, the γ-mercaptopropyltrimethoxysilane was purchased from Hubei Xingfa Group, and the model number is XFG-301.

[0008] According to a preferred embodiment of the present invention, the toluene was purchased from Sinopec Zhenhai Refining & Chemical Company and was industrial grade toluene (S-100).

[0009] According to a preferred embodiment of the present invention, the hydrochloric acid was purchased from Luxi Chemical Group Co., Ltd., and is a 36% industrial grade concentrated hydrochloric acid.

[0010] According to a preferred embodiment of the present invention, the triethyl phosphite was purchased from Jiangsu Feixiang Chemical Co., Ltd., and the product name is FY-03.

[0011] According to a preferred embodiment of the present invention, the triethylamine was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and the product name was A100208 (analytical grade).

[0012] According to a preferred embodiment of the present invention, the nitrogen gas is purchased from Yingde Gas Co., Ltd., and is industrial-grade high-purity nitrogen gas (purity ≥99.999%).

[0013] According to a preferred embodiment of the present invention, the deionized water is purchased from Hangzhou Wahaha Group Co., Ltd., and is laboratory-grade deionized water (conductivity ≤10μS / cm).

[0014] According to a preferred embodiment of the present invention, the nano-alumina was purchased from Jiangsu Tianniao High-Tech Co., Ltd., and the model is T300 (particle size 50nm).

[0015] According to a preferred embodiment of the present invention, the benzotriazole was purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd., and the model number is RY-800.

[0016] According to a preferred embodiment of the present invention, the hydroxypropyl methylcellulose was purchased from Shandong Heda Co., Ltd., and the model is HPMC-20000 (viscosity 20000mPa·s).

[0017] According to a preferred embodiment of the present invention, the silicone defoamer was purchased from Jiangsu Sixin Technology Application Research Institute Co., Ltd., and the model is SAG-630 (for water-based systems).

[0018] According to a preferred embodiment of the present invention, the ethyl acetate was purchased from Jiangsu Suopu (Group) Co., Ltd., and was industrial grade ethyl acetate (purity ≥99.5%).

[0019] In this invention, the preparation mechanism of bis(γ-mercaptopropyl)phosphonate-modified polysiloxane includes: In the first step of the hydrolysis reaction, under the action of anhydrous toluene and hydrochloric acid, the methoxy group (-OCH3) in the γ-mercaptopropyltrimethoxysilane molecule is protonated under acidic conditions, the bond energy between the silicon atom and the oxygen atom weakens, the methoxy group is released as a leaving group, and the silicon atom combines with water molecules to generate silanol (-Si-OH). This process is a typical silane hydrolysis reaction. Hydrochloric acid not only provides protons to promote the protonation of the methoxy group, but also inhibits the condensation and polymerization of silanol by lowering the pH value of the system, ensuring the formation of a highly active monofunctional silanol intermediate (γ-mercaptopropyltrihydroxysilane). In the second step of the esterification reaction, after removing toluene and water by vacuum distillation, the residual silanol in the system undergoes a nucleophilic substitution reaction with triethyl phosphite under alkaline conditions (triethylamine neutralizing hydrochloric acid). The hydroxyl group (-OH) of the silanol acts as a nucleophile, attacking the phosphorus atom (P is the central atom, carrying a partial positive charge) of triethyl phosphite to form a phosphorooxy intermediate. Subsequently, the intermediate loses its ethoxy group (-OCH2CH3) to generate a phosphonate group (-OP(O)(OCH2CH3)2), which is then hydrolyzed to yield a modified polysiloxane containing a phosphonic acid group (-PO3H2). In this process, triethylamine not only neutralizes the acid but also enhances the deprotonation of the hydroxyl group by increasing the basicity of the system, thereby strengthening its nucleophilic ability and ensuring the efficient esterification reaction.

[0020] According to a preferred embodiment of the present invention, in step A1, the volume ratio of γ-mercaptopropyltrimethoxysilane to anhydrous toluene is 1:(7-9); the reflux reaction time is 4-6 h.

[0021] According to a preferred embodiment of the present invention, in step A2, the reaction time is 8-10 h at 100-102 °C; the crude product is extracted with ethyl acetate 3-4 times.

[0022] According to a preferred embodiment of the present invention, the preparation method of the 1,3-bis(2-hydroxyethylimidazolinone) modified perfluoroepoxy resin includes: B1, dissolving perfluorooctyl epoxy resin in N,N-dimethylformamide, adding 1,3-bis(2-hydroxyethylimidazolinone) and tetramethylammonium bromide, and heating to 120-122°C to react and generate an ether-linked intermediate; B2, subsequently adding trifluoroethyl methacrylate and benzoyl peroxide, and continuing the reaction at 80-82°C; after the reaction is completed, cooling to room temperature, washing the product with deionized water, and vacuum drying at 60-62°C.

[0023] According to a preferred embodiment of the present invention, the perfluorooctyl epoxy resin was purchased from Wuhan Organic Industry Co., Ltd., and the model is AF-800 (perfluorooctyl modified epoxy resin, epoxy value 0.8-1.0 eq / 100g).

[0024] According to a preferred embodiment of the present invention, the N,N-dimethylformamide was purchased from Jiangsu Feixiang Chemical Co., Ltd., and the model was DMF-99.9 (industrial grade high-purity solvent, purity ≥99.9%).

[0025] According to a preferred embodiment of the present invention, the 1,3-bis(2-hydroxyethylimidazolinone) was purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd., and the product name was RY-500 (industrial grade, purity ≥98%).

[0026] According to a preferred embodiment of the present invention, the tetramethylammonium bromide was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., model A101234 (analytical grade, purity ≥99%).

[0027] According to a preferred embodiment of the present invention, the trifluoroethyl methacrylate was purchased from Zhejiang Xin'an Chemical Group Co., Ltd., and the product type is M-100 (industrial grade, purity ≥97%).

[0028] According to a preferred embodiment of the present invention, the benzoyl peroxide was purchased from Hebei Jiheng Chemical Co., Ltd., and the model is BPO-98 (industrial grade, purity ≥98%).

[0029] According to a preferred embodiment of the present invention, the high-speed stirring vessel was purchased from Wuxi Huaxi Machinery Co., Ltd., model WH-500L (volume 500L, speed range 0-500rpm, with temperature control system).

[0030] In this invention, the preparation mechanism of 1,3-bis(2-hydroxyethylimidazolone) modified perfluoroepoxy resin includes: In the first step of the ether linkage reaction, the epoxy group (-COC-) of the perfluorooctyl epoxy resin is nucleophilically attacked by the hydroxyl group (-OH) on the imidazolone ring in N,N-dimethylformamide (a polar aprotic solvent). The carbon atom of the epoxy group (carrying a partial positive charge) is attacked by the hydroxyl oxygen, forming a three-membered ring transition state; subsequently, the three-membered ring opens, and the epoxy group is converted into an ether bond (-O-), generating an intermediate containing an ether bond. Tetramethylammonium bromide acts as a phase transfer catalyst, and by combining its quaternary ammonium cation with the anion (such as bromide ion) in the reaction system, it lowers the activation energy of the reaction and accelerates the ring-opening reaction of the epoxy group. In the second step of the free radical polymerization reaction, the added trifluoroethyl methacrylate (containing unsaturated double bonds) and benzoyl peroxide (BPO) undergo a decomposition-initiated reaction at 80-82℃: BPO decomposes to produce benzoyloxy radicals (-OC(O)C6H5), which attack the double bonds (π bonds) of trifluoroethyl methacrylate to form a carbon radical intermediate; this intermediate undergoes addition reactions with the double bonds of other trifluoroethyl methacrylate molecules to form a long-chain polymer. Simultaneously, the hydroxyl groups in the intermediate molecule (from the imidazolinone ring) further esterify with the hydroxyl groups at the polymer chain ends, extending the fluorocarbon chain (-C8F... 17 This process introduces a molecular structure, ultimately forming a modified epoxy resin containing imidazolinone rings and fluorocarbon chains. In this process, free radical polymerization is completed through three steps: chain initiation, chain propagation, and chain termination, ensuring that the fluorocarbon chains are uniformly distributed on the molecular chain and improving the hydrophobicity of the material.

[0031] According to a preferred embodiment of the present invention, in step B1, the reaction time is 6-8 hours after heating to 120-122°C.

[0032] According to a preferred embodiment of the present invention, in step B2, the reaction is continued at 80-82°C for 4-6 hours; the washing with deionized water is performed 3-4 times; and the vacuum drying time is 12-14 hours.

[0033] The present invention also provides a method for preparing the aforementioned high-durability metal corrosion inhibitor, comprising the following steps: S1. Add bis(γ-mercaptopropyl)phosphonate-modified polysiloxane and 1,3-bis(2-hydroxyethylimidazolinone)-modified perfluoroepoxy resin to a high-speed stirred tank and heat to 50-52℃ to mix. S2. Then, add deionized water, ultrasonically dispersed nano-alumina, benzotriazole, hydroxypropyl methylcellulose and organosilicon defoamer in sequence, and continue stirring until the system is homogeneous. S3. Finally, the particles are ground in a sand mill to make the particle size ≤3μm.

[0034] In this invention, the preparation mechanisms of the two modified compounds ultimately work synergistically to improve the overall performance of the preservative. Bis(γ-mercaptopropyl)phosphonate-modified polysiloxanes form strong chemical bonds (such as Fe-S bonds) with sulfides or oxides on the metal surface through the mercapto group (-SH). The phosphonate group (-PO3H2) hydrolyzes to generate phosphate (-PO3) ions. 2- The 1,3-bis(2-hydroxyethylimidazolone) modified perfluoroepoxy resin forms a sparingly soluble phosphate film by complexing with metal ions. Simultaneously, the high bond energy (452 ​​kJ / mol) of the polysiloxane backbone (-Si-O-Si-) ensures the chemical bonding between the coating and the metal. The imidazolone ring (containing N and O atoms) of the 1,3-bis(2-hydroxyethylimidazolone) modified perfluoroepoxy resin forms a six-membered ring chelate with metal ions, inhibiting metal dissolution. The extremely low surface energy of the fluorocarbon chain hinders the penetration of water, oxygen, and Cl⁻. The cross-linked structures formed by esterification and polymerization reactions of the two modified compounds (such as pre-cross-linking of epoxy and hydroxyl groups) are combined with nano-alumina fillers and benzotriazole (with Cu...) 2+ The components (such as complexing agents) work synergistically to construct a multi-protective mechanism of "adsorption-complexing-barrier", ultimately achieving long-term effectiveness and stability of metal corrosion inhibitors.

[0035] According to a preferred embodiment of the present invention, in step S1, the speed of the high-speed stirring vessel is 300-400 rpm; the mixing time at 50-52°C is 15-20 min.

[0036] According to a preferred embodiment of the present invention, in step S2, the ultrasonic dispersion time is 20-30 min and the power is 200-300 W; the stirring speed is 800-850 rpm and the time is 2-4 h.

[0037] According to a preferred embodiment of the present invention, in step S3, the mill speed is 1500-2000 rpm and the grinding time is 3-6 hours.

[0038] The beneficial effects of this invention are as follows: This invention significantly improves the long-lasting effect and protective performance of metal corrosion inhibitors through the synergistic effect of two novel modified compounds and the optimized combination with traditional fillers. The specific technical effects are reflected in the following aspects: Traditional metal corrosion inhibitors mostly rely on physical adsorption and simple chemical reactions, resulting in weak adhesion to metal surfaces and susceptibility to blistering and peeling due to mechanical friction or environmental stress. In this invention, the thiol groups (-SH) in bis(γ-mercaptopropyl)phosphonate-modified polysiloxane can form strong chemical bonds (high bond energy) with the metal surface. The phosphate groups generated after hydrolysis of the phosphonate groups can complex with metal ions, simultaneously constructing a dense adsorption layer on the metal surface. The imidazolinone ring of the 1,3-bis(2-hydroxyethylimidazolinone)-modified perfluoroepoxy resin contains N and O atoms, which can form stable chelates with metal ions. These two modified compounds, through multiple chemical reactions, tightly bond with the metal surface, significantly improving the coating's peel strength and preventing detachment during long-term use, effectively solving the problem of weak interfacial adhesion in traditional corrosion inhibitors.

[0039] In complex corrosive environments, a single corrosion inhibition mechanism is insufficient to cope with the synergistic effects of multiple factors, leading to the failure of corrosion inhibitors. This invention inhibits corrosion through multiple synergistic corrosion inhibition mechanisms: the chelating effect of the imidazolinone ring directly inhibits metal dissolution; the phosphate ions generated by the hydrolysis of phosphonate groups form a sparingly soluble phosphate film with metal ions, covering surface micro-defects; and the extremely low surface energy of the fluorocarbon chain hinders the penetration of water, oxygen, and chloride ions. These three mechanisms target the corrosion initiation, propagation, and penetration stages respectively, forming a triple protection of "adsorption-complexation-barrier," effectively inhibiting various corrosion types such as uniform corrosion and pitting corrosion, and maintaining high-efficiency protective performance even in harsh environments such as humidity and salt spray.

[0040] In practical applications, the corrosion inhibitor of this invention exhibits significantly superior overall performance compared to traditional products. Nano-alumina, acting as a filler, enhances the mechanical strength of the coating; hydroxypropyl methylcellulose regulates workability; and an organosilicon defoamer ensures coating uniformity. The preparation method, through steps such as reflux, extraction, and polymerization, guarantees the uniformity of the modified compound structure, while the sand milling process results in fine, non-porous particles. Tests show that the coating exhibits no rust during prolonged salt spray testing, high peel strength to metal, excellent aging resistance, and a significantly extended maintenance cycle for metal components, thereby substantially reducing equipment replacement and maintenance costs caused by corrosion. Detailed Implementation

[0041] The following detailed embodiments are only used to further illustrate this application and should not be construed as limiting the scope of protection of this application. Those skilled in the art can make some non-essential improvements and adjustments to this application based on the above application content.

[0042] Example 1 Preparation of bis(γ-mercaptopropyl)phosphonate-modified polysiloxane: 200g of γ-mercaptopropyltrimethoxysilane was dissolved in 1600mL of anhydrous toluene (dried by molecular sieve, moisture content ≤0.01%) (volume ratio 1:8), and 5mL of 36% industrial grade concentrated hydrochloric acid was added. The mixture was refluxed at 61℃ for 5h with stirring at 200rpm during reflux. After the reaction, toluene and water were removed by vacuum distillation (vacuum degree ≤-0.09MPa, temperature ≤50℃) to obtain crude γ-mercaptopropyltrihydroxysilane intermediate. The crude product was transferred to a three-necked flask and phosphorous acid was added. 120 mL of triethyl phosphite and 8 mL of triethylamine were reacted at 101 °C for 9 h (heating rate 5 °C / min). High-purity nitrogen was continuously introduced during the reaction to isolate moisture, and the mixture was stirred at 300 rpm. After the reaction, unreacted triethyl phosphite and triethylamine were removed by vacuum distillation. The crude product was extracted three times with ethyl acetate (100 mL each time). The combined organic phases were purified by silica gel column chromatography (eluent: petroleum ether: ethyl acetate = 5:1, flow rate 2 mL / min). The main fraction was collected and the solvent was removed by rotary evaporation to obtain bis(γ-mercaptopropyl)phosphonate modified polysiloxane.

[0043] Preparation of 1,3-bis(2-hydroxyethylimidazolinone) modified perfluoroepoxy resin: 300g of perfluorooctyl epoxy resin was dissolved in 1500mL of N,N-dimethylformamide. 60g of 1,3-bis(2-hydroxyethylimidazolinone) and 1.5g of tetramethylammonium bromide were added at 121℃, and the mixture was stirred at 300rpm for 7h. Subsequently, the temperature was raised to 81℃ (heating rate 3℃ / min), and 120mL of trifluoroethyl methacrylate was added dropwise (1mL / min). At the same time, 3g of benzoyl peroxide was added to initiate free radical polymerization. The reaction was maintained at 81℃ for 5h (with nitrogen protection during the reaction). After the reaction was completed, the mixture was cooled to room temperature, and the product was washed three times with deionized water (200mL each time). The product was then dried under vacuum at 61℃ (vacuum degree ≤ -0.095MPa) for 13h to obtain 1,3-bis(2-hydroxyethylimidazolinone) modified perfluoroepoxy resin.

[0044] Preparation of a high-durability metal corrosion inhibitor: 225g of bis(γ-mercaptopropyl)phosphonate-modified polysiloxane and 300g of 1,3-bis(2-hydroxyethylimidazolone)-modified perfluoroepoxy resin were added to a 304 stainless steel high-speed stirred tank (volume 500L) and mixed at 350rpm at 51℃ for 18min (anchor-type stirrer); then 350g of deionized water and 65g of nano-alumina ultrasonically dispersed (frequency 40kHz, power 250W, time 25min) were added sequentially. The following ingredients were added: 12.5g benzotriazole, 10g hydroxypropyl methylcellulose (viscosity 20000mPa·s, industrial grade), and 3g silicone defoamer (water-based system specific, industrial grade). The mixture was stirred at 830rpm for 3 hours. Finally, it was ground for 4 hours (1800rpm) using a sand mill (zirconium beads 0.3mm, volume 10L) to control the particle size to ≤3μm (D90≤3μm as measured by a laser particle size analyzer), thus obtaining a high-durability metal corrosion inhibitor.

[0045] Example 2 Preparation of bis(γ-mercaptopropyl)phosphonate-modified polysiloxane: 250g of γ-mercaptopropyltrimethoxysilane was dissolved in 2000mL of anhydrous toluene (dried by molecular sieve, moisture content ≤0.01%), and 6mL of 36% industrial grade concentrated hydrochloric acid was added. The mixture was refluxed at 60℃ for 4h with stirring at 200rpm during reflux. After the reaction, toluene and water were removed by vacuum distillation (vacuum degree ≤-0.09MPa, temperature ≤50℃) to obtain crude γ-mercaptopropyltrihydroxysilane intermediate. The crude product was transferred to a three-necked flask, and 1g of triethyl phosphite was added. 50 mL of triethylamine and 10 mL of phosphite were added and heated to 100 °C for 8 h (heating rate 5 °C / min). High-purity nitrogen was continuously introduced during the reaction to isolate moisture, and the mixture was stirred at 300 rpm. After the reaction, unreacted triethyl phosphite and triethylamine were removed by vacuum distillation. The crude product was extracted three times with ethyl acetate (100 mL each time). The organic phases were combined and purified by silica gel column chromatography (eluent: petroleum ether: ethyl acetate = 5:1, flow rate 2 mL / min). The main fraction was collected and the solvent was removed by rotary evaporation to obtain bis(γ-mercaptopropyl)phosphonate modified polysiloxane.

[0046] Preparation of 1,3-bis(2-hydroxyethylimidazolinone) modified perfluoroepoxy resin: 350g of perfluorooctyl epoxy resin (epoxy value 0.8-1.0 eq / 100g, industrial grade) was dissolved in 1800mL of N,N-dimethylformamide. 70g of 1,3-bis(2-hydroxyethylimidazolinone) and 2g of tetramethylammonium bromide were added at 120℃, and the mixture was stirred at 300rpm for 6h. Subsequently, the temperature was raised to 80℃ (heating rate 3℃ / min). (n) Add 140 mL of trifluoroethyl methacrylate (1 mL / min) dropwise, and simultaneously add 4 g of benzoyl peroxide to initiate free radical polymerization. Maintain the reaction temperature at 80 °C for 4 h (with nitrogen protection during the reaction). After the reaction is completed, cool to room temperature, wash the product three times with deionized water (200 mL each time), and dry under vacuum at 60 °C (vacuum degree ≤ -0.095 MPa) for 12 h to obtain 1,3-bis(2-hydroxyethylimidazolinone) modified perfluoroepoxy resin.

[0047] Preparation of a high-durability metal corrosion inhibitor: 250g of bis(γ-mercaptopropyl)phosphonate-modified polysiloxane and 350g of 1,3-bis(2-hydroxyethylimidazolone)-modified perfluoroepoxy resin were added to a 304 stainless steel high-speed stirred tank (volume 500L) and mixed at 380rpm at 52℃ for 20min (anchor-type stirrer); subsequently, 400g of deionized water and 80g of nano-oxidation material that had been ultrasonically dispersed (frequency 40kHz, power 300W, time 30min) were added sequentially. Aluminum (particle size 50nm), 15g benzotriazole, 12g hydroxypropyl methylcellulose (viscosity 20000mPa·s, industrial grade), and 4g silicone defoamer (water-based system specific, industrial grade) were stirred at 850rpm for 4 hours. Finally, the mixture was ground for 6 hours (2000rpm) using a sand mill (zirconium beads 0.3mm, volume 10L) to control the particle size to ≤3μm (D90≤3μm as measured by a laser particle size analyzer), thus obtaining a high-durability metal corrosion inhibitor.

[0048] Example 3 Preparation of bis(γ-mercaptopropyl)phosphonate-modified polysiloxane: 180g of γ-mercaptopropyltrimethoxysilane was dissolved in 1620mL of anhydrous toluene (dried by molecular sieve, moisture content ≤0.01%), and 5.4mL of 36% industrial grade concentrated hydrochloric acid was added. The mixture was refluxed at 62℃ for 6h with stirring at 200rpm during reflux. After the reaction, toluene and water were removed by vacuum distillation (vacuum degree ≤-0.09MPa, temperature ≤50℃) to obtain crude γ-mercaptopropyltrihydroxysilane intermediate. The crude product was transferred to a three-necked flask, and 1g of triethyl phosphite was added. 0.8 mL of triethylamine and 7.2 mL of phosphite were added and the mixture was heated to 102 °C and reacted for 10 h (heating rate 5 °C / min). High-purity nitrogen was continuously introduced during the reaction to isolate moisture, and the mixture was stirred at 300 rpm. After the reaction, unreacted triethyl phosphite and triethylamine were removed by vacuum distillation. The crude product was extracted three times with ethyl acetate (100 mL each time). The combined organic phases were purified by silica gel column chromatography (eluent: petroleum ether: ethyl acetate = 5:1, flow rate 2 mL / min). The main fraction was collected and the solvent was removed by rotary evaporation to obtain bis(γ-mercaptopropyl)phosphonate modified polysiloxane.

[0049] Preparation of 1,3-bis(2-hydroxyethylimidazolinone) modified perfluoroepoxy resin: 250g of perfluorooctyl epoxy resin was dissolved in 1250mL of N,N-dimethylformamide. 50g of 1,3-bis(2-hydroxyethylimidazolinone) and 1.25g of tetramethylammonium bromide (0.5% of the mass of the perfluorooctyl epoxy resin) were added at 122℃, and the mixture was stirred at 300rpm for 8h. Subsequently, the temperature was increased to 82℃ (heating rate 3℃ / min). 100 mL of trifluoroethyl methacrylate was added dropwise (1 mL / min), and 2.5 g of benzoyl peroxide was added simultaneously to initiate free radical polymerization. The reaction was maintained at 82 °C for 6 h (with nitrogen protection during the reaction). After the reaction was completed, the product was cooled to room temperature, washed three times with deionized water (200 mL each time), and dried under vacuum at 62 °C (vacuum degree ≤ -0.095 MPa) for 14 h to obtain 1,3-bis(2-hydroxyethylimidazolinone) modified perfluoroepoxy resin.

[0050] Preparation of a high-durability metal corrosion inhibitor: 180g of bis(γ-mercaptopropyl)phosphonate-modified polysiloxane and 250g of 1,3-bis(2-hydroxyethylimidazolone)-modified perfluoroepoxy resin were added to a 304 stainless steel high-speed stirred tank (volume 500L) and mixed at 320rpm at 50℃ for 15min (anchor-type stirrer); then 300g of deionized water and 50g of nano-oxygenated resin that had been ultrasonically dispersed (frequency 40kHz, power 200W, time 20min) were added sequentially. Alumina (50nm particle size), 10g benzotriazole, 8g hydroxypropyl methylcellulose (viscosity 20000mPa·s, industrial grade), and 2g silicone defoamer (water-based system specific, industrial grade) were stirred at 800rpm for 2 hours. Finally, the mixture was ground for 3 hours (1500rpm) using a sand mill (zirconium beads 0.3mm specification, volume 10L) to control the particle size to ≤3μm (D90≤3μm as measured by a laser particle size analyzer), thus obtaining a high-durability metal corrosion inhibitor.

[0051] Comparative Example 1 The specific implementation method is the same as in Example 1, except that the high-durability metal corrosion inhibitor is prepared by adding 0g of bis(γ-mercaptopropyl)phosphonate-modified polysiloxane and 300g of 1,3-bis(2-hydroxyethylimidazolinone)-modified perfluoroepoxy resin to a high-speed stirred tank.

[0052] Comparative Example 2 The specific implementation method is the same as in Example 1, except that the high-durability metal corrosion inhibitor is prepared by adding 225g of bis(γ-mercaptopropyl)phosphonate-modified polysiloxane and 0g of 1,3-bis(2-hydroxyethylimidazolinone)-modified perfluoroepoxy resin to a high-speed stirred tank.

[0053] Comparative Example 3 The specific implementation method is the same as in Example 1, except that the preparation of the high-durability metal corrosion inhibitor is as follows: 0g of bis(γ-mercaptopropyl)phosphonate modified polysiloxane and 0g of 1,3-bis(2-hydroxyethylimidazolinone) modified perfluorinated epoxy resin are added to a high-speed stirring tank, along with 450g of deionized water, 100g of nano alumina, 20g of benzotriazole, 15g of hydroxypropyl methylcellulose and 5g of organosilicon defoamer (mainly based on the basic components).

[0054] Performance testing The biodegradable composite materials prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance testing according to the following methods: 1. Corrosion Inhibition Efficiency Test (Weight Loss Method): Take a Q235 steel sample with dimensions of 50mm×50mm×3mm, sand it to 1200 mesh, remove oil with acetone, and dry it with cold air. Weigh the initial mass (m0). Immerse the sample completely in a 3.5wt% NaCl solution (pH=7.0, 25℃) for 24h, 48h, and 72h respectively. Remove the sample, rinse the surface corrosion products with deionized water, dry it with cold air, and weigh the final mass (m1). The corrosion inhibition efficiency (η) is calculated as follows: η=[(m0-m1) / (m0-m0')×100%], where m0' is the mass loss of the blank sample (without anti-corrosion coating) after immersion for the same period.

[0055] 2. Coating Adhesion Test (Raman Spectroscopy): A laser confocal Raman spectrometer (excitation wavelength 532 nm) was used to test the Q235 steel specimen coated with the preservative (after 7 days of curing). Test conditions: Scanning range 100-1800 cm⁻¹ -1 Integration time 10s, accumulated 3 times. Analysis of Fe-S bonds (approximately 250cm²) was performed. -1 ), Fe-O bond (approximately 800 cm -1 The characteristic peak intensity of ) is used to calculate the binding energy (E): E=Σ(I_Fe-S / I_Fe-O)×100%, where I is the corresponding peak intensity. The higher the binding energy, the stronger the adhesion.

[0056] 3. Salt spray test (GB / T 1771-2007): The Q235 steel test piece coated with corrosion inhibitor (coating thickness 50±5μm) is suspended in the salt spray test chamber. Test conditions: 5wt% NaCl solution, pH=6.5-7.2, spray pressure 0.07-0.17MPa, test chamber temperature 35±2℃, spray continuously for 96h and then take it out and observe the surface corrosion (no corrosion is qualified, corrosion area >5% is unqualified).

[0057] 4. Moist heat resistance test (GB / T 1740-2007): Place the Q235 steel test piece coated with corrosion inhibitor in a constant temperature and humidity chamber. Test conditions: temperature 85±2℃, relative humidity 85±5%, for 200 hours. After 200 hours, take it out and observe whether the coating bulges or peels off (no bulging / peeling is qualified, bulging area >10% or peeling length >2mm is unqualified).

[0058] 5. Performance test results: Table 1: Performance test results of each embodiment and comparative example ; As shown in Table 1, the performance test results clearly demonstrate the core advantages of this invention, highlighting the significant differences between Examples 1-3 and Comparative Tables 1-3. In Examples 1-3, the synergistic effect of bis(γ-mercaptopropyl)phosphonate-modified polysiloxane and 1,3-bis(2-hydroxyethylimidazolone)-modified perfluoroepoxy resin effectively solves the core problems of poor long-term performance and weak bonding with metal interfaces in traditional metal corrosion inhibitors. Specifically: Firstly, regarding corrosion inhibition efficiency, Examples 1-3 achieved corrosion inhibition efficiencies exceeding 97% (up to 98.5%) at both 24 and 72 hours, significantly higher than Comparative Examples 1-3 (up to only 93.1%). This is because the two modified compounds form strong chemical bonds (such as Fe-S bonds) with sulfides / oxides on the metal surface via thiol groups, and the phosphate groups generated by the hydrolysis of phosphonate groups complex with metal ions to form a sparingly soluble phosphate film. Simultaneously, the N / O atoms of the imidazolinone ring form a six-membered ring chelate with metal ions. These three factors synergistically inhibit metal dissolution, significantly improving corrosion inhibition performance.

[0059] Secondly, regarding coating adhesion, the Fe-S bond bonding energy of Examples 1-3 (81.5%-83.1%) is significantly higher than that of the comparative examples (52.1%-68.7%), indicating a stronger chemical bond with the metal surface. This is because the polysiloxane backbone (-Si-O-Si-) of the bis(γ-mercaptopropyl)phosphonate-modified polysiloxane has high bond energy, and the side chain thiol groups form irreversible chemical bonds with the metal. Furthermore, the cross-linking of epoxy and hydroxyl groups in the 1,3-bis(2-hydroxyethylimidazolinone)-modified perfluoroepoxy resin further enhances the interfacial bonding, solving the problem of easy detachment caused by traditional preservatives relying solely on physical adsorption.

[0060] Finally, regarding environmental adaptability, Examples 1-3 showed no rust after 96 hours in a 5wt% NaCl solution and no blistering / peeling after 200 hours in a humid heat environment at 85°C / 85%RH, while Comparative Examples 1-3 showed rust (up to 15% of the area) or blistering (Comparative Example 3). This is due to the extremely low surface energy of the fluorocarbon chain of the 1,3-bis(2-hydroxyethylimidazolinone) modified perfluoroepoxy resin, which hinders the entry of water, O2, and Cl. - The two modified compounds penetrated the environment, and their cross-linked structure formed a dense physical barrier, which together resisted the erosion of the complex corrosive environment.

[0061] In summary, Examples 1-3, through the synergistic effect of two novel modified compounds, constructed a multi-protection mechanism of "chemical adsorption-complex corrosion inhibition-physical barrier", which significantly improved the long-term effectiveness and interfacial bonding of metal corrosion inhibitors and effectively solved the core problem of traditional corrosion inhibitors being prone to failure under harsh environments.

[0062] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A highly durable metal corrosion inhibitor, characterized in that, Including the following parts by weight of raw materials: Bis(γ-mercaptopropyl)phosphonate-modified polysiloxane: 150-300 parts by weight; 1,3-Bis(2-hydroxyethylimidazolinone) modified perfluoroepoxy resin: 200-400 parts by weight; Deionized water: 250-450 parts by weight; Nano-alumina: 30-100 parts by weight; Benzotriazole: 5-20 parts by weight; Hydroxypropyl methylcellulose: 5-15 parts by weight; Organosilicon defoamer: 1-5 parts by weight; The preparation method of the bis(γ-mercaptopropyl)phosphonate-modified polysiloxane includes: A1, dissolving γ-mercaptopropyltrimethoxysilane in anhydrous toluene, adding hydrochloric acid, and refluxing at 60-62℃; A2, removing toluene and water by vacuum distillation, transferring the product to a three-necked flask, adding triethyl phosphite and triethylamine, heating to 100-102℃, and finally hydrolyzing to obtain bis(γ-mercaptopropyl)phosphonate-modified polysiloxane; nitrogen gas is continuously introduced during the reaction to isolate moisture, and the crude product is purified by ethyl acetate extraction and column chromatography.

2. The high-durability metal corrosion inhibitor according to claim 1, characterized in that, In step A1, the volume ratio of γ-mercaptopropyltrimethoxysilane to anhydrous toluene is 1:(7-9); the reflux reaction time is 4-6 h.

3. The high-durability metal corrosion inhibitor according to claim 1, characterized in that, In step A2, the reaction time is 8-10 h at 100-102℃; the crude product is extracted with ethyl acetate 3-4 times.

4. The high-durability metal corrosion inhibitor according to claim 1, characterized in that, The preparation method of the 1,3-bis(2-hydroxyethylimidazolinone) modified perfluoroepoxy resin includes: B1, dissolving perfluorooctyl epoxy resin in N,N-dimethylformamide, adding 1,3-bis(2-hydroxyethylimidazolinone) and tetramethylammonium bromide, and heating to 120-122℃ to react and generate an ether-linked intermediate; B2, subsequently adding trifluoroethyl methacrylate and benzoyl peroxide, and continuing the reaction at 80-82℃; after the reaction is completed, cooling to room temperature, washing the product with deionized water, and vacuum drying at 60-62℃.

5. The high-durability metal corrosion inhibitor according to claim 4, characterized in that, In step B1, the temperature is raised to 120-122℃ and the reaction time is 6-8 hours.

6. The high-durability metal corrosion inhibitor according to claim 4, characterized in that, In step B2, the reaction continues at 80-82℃ for 4-6 hours; the washing with deionized water is performed 3-4 times; and the vacuum drying time is 12-14 hours.

7. A method for preparing a high-durability metal corrosion inhibitor according to any one of claims 1-6, characterized in that, step... include: S1. Add bis(γ-mercaptopropyl)phosphonate-modified polysiloxane and 1,3-bis(2-hydroxyethylimidazolinone)-modified perfluoroepoxy resin to a high-speed stirred tank and heat to 50-52℃ to mix. S2. Then, add deionized water, ultrasonically dispersed nano-alumina, benzotriazole, hydroxypropyl methylcellulose and organosilicon defoamer in sequence, and continue stirring until the system is homogeneous. S3. Finally, the particles are ground in a sand mill to make the particle size ≤3μm.

8. The preparation method according to claim 7, characterized in that, In step S1, the speed of the high-speed stirring vessel is 300-400 rpm; the mixing time is 15-20 min at 50-52℃.

9. The preparation method according to claim 7, characterized in that, In step S2, the ultrasonic dispersion time is 20-30 min and the power is 200-300 W; the stirring speed is 800-850 rpm and the time is 2-4 h.

10. The preparation method according to claim 7, characterized in that, In step S3, the mill speed is 1500-2000 rpm and the grinding time is 3-6 hours.