Environment-friendly stainless steel cleaning agent and preparation method thereof

Abstract

This invention discloses an environmentally friendly stainless steel cleaning agent and its preparation method, belonging to the field of fine chemical technology. The cleaning agent is a homogeneous and transparent liquid, comprising 30-60 parts of a eutectic solvent, 10-25 parts of a composite surfactant, 5-15 parts of a pH-responsive microcapsule corrosion inhibitor, 5-12 parts of a chelating detergent, and deionized water. The eutectic solvent is prepared by combining a hydrogen bond donor and a hydrogen bond acceptor in a molar ratio of 1:1 to 4:1. The pH-responsive microcapsule corrosion inhibitor has a pH-sensitive polymer as the capsule wall and the corrosion inhibitor as the core, with a particle size of 0.5-5 micrometers. It remains intact at a storage state of pH 9.0-11.0 and ruptures and releases its contents during the cleaning process when the micro-areas on the stainless steel surface acidify to 6.5-7.5. The chelating detergent is tetrasodium glutamate diacetate or tetrasodium iminodisuccinate. This invention achieves a balance between efficient cleaning and on-demand rust prevention through the synergistic effect of these three components, exhibiting excellent cleaning performance, extremely low corrosion rate, and good environmental friendliness.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical technology, specifically relating to an environmentally friendly stainless steel cleaning agent and its preparation method. Background Technology

[0002] Stainless steel is widely used in kitchen equipment, medical devices, and industrial manufacturing. Its surface is easily contaminated with oil, oxides, and other pollutants, requiring regular cleaning. Existing cleaning agents are mainly divided into two categories: solvent-based and water-based. Solvent-based cleaning agents remove oil quickly but contain volatile organic compounds, which are flammable, explosive, and environmentally unfriendly. Traditional water-based cleaning agents often rely on strong alkalis, strong acids, or high-concentration surfactants, which can easily corrode or discolor stainless steel and are difficult to rinse.

[0003] Regarding corrosion inhibition technology, existing cleaning agents typically add corrosion inhibitors such as benzotriazoles directly in free form, causing them to be consumed prematurely during storage and the initial cleaning phase. This makes it difficult to provide targeted protection during the micro-corrosion-sensitive stage of the stainless steel surface during cleaning. Although some studies have used microencapsulated corrosion inhibitors, existing microcapsules are mostly designed to rupture under alkaline or neutral conditions, making it impossible to remain inert during storage and accurately match the micro-acidification period of the stainless steel surface during cleaning.

[0004] Furthermore, the synergistic effect of the components in existing cleaning agents is generally insufficient, and the detergency and protective functions lack effective coupling in time and space. Conventional chelating detergent builders such as EDTA have poor biodegradability, and although low eutectic solvents have potential in disrupting the oil-stain interface, they have not yet been systematically integrated with pH-responsive microencapsulated corrosion inhibitors and biodegradable chelating agents. Summary of the Invention

[0005] To address the technical deficiencies in the background technology, this invention proposes an environmentally friendly stainless steel cleaning agent and its preparation method, which solves the aforementioned technical problems and meets practical needs. The specific technical solution is as follows: An environmentally friendly stainless steel cleaning agent, wherein the cleaning agent is a homogeneous and transparent liquid, comprising the following components by weight: 30-60 parts of eutectic solvent, 10-25 parts of composite surfactant, 5-15 parts of pH-responsive microcapsule corrosion inhibitor, 5-12 parts of chelating detergent, and the balance being deionized water. The eutectic solvent is prepared by heating and stirring a hydrogen bond donor and a hydrogen bond acceptor in a molar ratio of 1:1 to 4:1. The pH-responsive microcapsule corrosion inhibitor is a microcapsule structure prepared with a pH-sensitive polymer as the capsule wall and a benzotriazole compound or a mercaptobenzothiazole compound as the core. The microcapsule maintains the integrity of the capsule wall when the initial pH value of the cleaning solution is 9.0-11.0 to inhibit the release of the corrosion inhibitor. During the cleaning process, when the pH value of the micro-area on the stainless steel surface decreases to 6.5-7.5, the capsule wall swells or ruptures to release the corrosion inhibitor. The pH-sensitive polymer is at least one of polyacrylic acid, chitosan, or acrylic acid-methacrylic acid copolymer, and the particle size of the pH-responsive microcapsule corrosion inhibitor is 0.5-5 micrometers; The chelating detergent is tetrasodium glutamate diacetate or tetrasodium iminodisuccinate. The eutectic solvent, pH-responsive microcapsule corrosion inhibitor, and chelating detergent builder form a synergistic system. The eutectic solvent disrupts the oil stain interface structure through a hydrogen bond network, and the chelating detergent builder complexes metal ions to enhance detergency. The pH-responsive microcapsule corrosion inhibitor releases its active ingredient only during the cleaning process to inhibit corrosion. The pH-responsive microcapsule corrosion inhibitor remains inert during storage. The release condition of the pH-responsive microcapsule corrosion inhibitor is: the active ingredient is released when the synergistic effect of the eutectic solvent and the chelating cleaning aid causes the micro-area of ​​the stainless steel surface to acidify to 6.5-7.5.

[0006] As a further technical solution of the present invention, the hydrogen bond donor is selected from one or more of urea, ethylene glycol, glycerol, citric acid, malic acid or oxalic acid, and the hydrogen bond acceptor is selected from one or more of choline chloride, betaine or tetrabutylammonium bromide.

[0007] As a further technical solution of the present invention, the composite surfactant is composed of a nonionic surfactant and an anionic surfactant in a weight ratio of 3:1 to 5:1, wherein the nonionic surfactant is an alkyl glycoside and / or fatty alcohol polyoxyethylene ether, and the anionic surfactant is... Sodium alkenyl sulfonate and / or sodium cocoyl methyl taurate.

[0008] As a further technical solution of the present invention, the core is one or more of benzotriazole, methylbenzotriazole or 2-mercaptobenzothiazole.

[0009] As a further technical solution of the present invention, the surface tension of the cleaning agent at 25°C is 25-35 mN / m, and the corrosion rate of the cleaning agent on 304 or 316L stainless steel substrate after immersion at 50°C for 4 hours is less than 0.01 mm / a.

[0010] As a further technical solution of the present invention, the mass ratio of the eutectic solvent to the chelating detergent is 3:1 to 10:1, and the molar ratio of hydrogen bond donor to hydrogen bond acceptor in the eutectic solvent is 2:1 to 3:1.

[0011] A method for preparing an environmentally friendly stainless steel cleaning agent based on any one of the above-mentioned methods, characterized by comprising the following steps: S001: Preparation of eutectic solvent: Mix hydrogen bond donor and hydrogen bond acceptor at a preset molar ratio, heat and stir at 60-100℃ for 1-4 hours until a homogeneous and transparent eutectic solvent is formed, and cool for later use. S002: Preparation of pH-responsive microcapsule corrosion inhibitors: pH-sensitive polymers are dissolved in organic solvents or aqueous phases as wall material solutions, and corrosion inhibitor cores are mixed with the wall material solutions. pH-responsive microcapsule corrosion inhibitors with a particle size range of 0.5-5 micrometers are prepared by emulsification solvent evaporation method or spray drying method. S003: Mixing and homogenization: Mix the eutectic solvent obtained in step S001 with deionized water, stir at 30-50℃, then add the composite surfactant and chelated detergent in sequence, continue stirring until completely dissolved to form a mixture, and adjust the pH to 9.0-10.5. S004: Introducing a sustained-release system: The pH-responsive microcapsule corrosion inhibitor obtained in step S002 is added to the mixture obtained in step S003, and stirred and dispersed at a speed of 300-800 rpm for 10-30 minutes until the microcapsules are uniformly suspended to obtain the environmentally friendly stainless steel cleaning agent.

[0012] As a further technical solution of the present invention, in step S002, a pH-responsive microcapsule corrosion inhibitor is prepared by an emulsification solvent evaporation method. The specific operation is as follows: the pH-sensitive polymer and the corrosion inhibitor core are dissolved together in dichloromethane or ethyl acetate as the oil phase, the oil phase is added to the aqueous phase containing the emulsifier, and high-speed shear emulsification is performed to form an oil-in-water emulsion. The organic solvent is evaporated by stirring, and the microcapsules are obtained after washing and drying.

[0013] As a further technical solution of the present invention, in step S003, the pH adjuster is one or more of citric acid, triethanolamine or potassium hydroxide, and the adjusted pH value enables the pH-responsive microcapsule corrosion inhibitor to maintain the integrity of the capsule wall in the storage state.

[0014] The beneficial effects of this invention are as follows: It achieves precise, on-demand release of the corrosion inhibitor: Utilizing pH-responsive microcapsule corrosion inhibitors, the capsule walls remain intact and the inhibitor remains inert during storage, releasing only during the cleaning process. This achieves precise spatiotemporal control of the rust-preventive effect, avoiding ineffective consumption of the inhibitor and its impact on cleaning efficiency. The synergistic effect of the eutectic solvent and chelating cleaning aid effectively destroys the oil stain structure and enhances detergency, while simultaneously creating a micro-acidification environment that triggers the release of the corrosion inhibitor. The resulting cleaning agent has a surface tension as low as 25-35 mN / m, with a corrosion rate of less than 0.01 mm / a for 304 or 316L stainless steel, exhibiting both excellent detergency and ultra-low corrosivity. All raw materials used are environmentally friendly, biodegradable, and low-toxicity, avoiding the use of traditional strong alkalis, strong acids, and phosphorus-containing additives, while also reducing the ineffective release of the corrosion inhibitor, meeting the requirements of green chemistry development. Attached Figure Description

[0015] Figure 1 This is a process flow diagram of an embodiment of the present invention. Detailed Implementation

[0016] The embodiments of the present invention will be described below with reference to the accompanying drawings and related examples. The embodiments of the present invention are not limited to the following examples, and the present invention relates to the relevant necessary components in this technical field, which should be regarded as well-known technology in this technical field and can be known and mastered by those skilled in this technical field.

[0017] Example 1

[0018] This embodiment provides an environmentally friendly stainless steel cleaning agent and its preparation method.

[0019] The preparation method of the cleaning agent in this embodiment includes the following steps: S001: Preparation of Eutectic Solvents Choline chloride and urea were accurately weighed at a molar ratio of 1:2. The weighed choline chloride and urea were placed in a three-necked flask equipped with a stirrer and thermometer, and heated in a constant-temperature water bath at 80°C with continuous stirring at 300 rpm. During heating and stirring, the mixture gradually changed from a solid mixture to a colorless, transparent, homogeneous liquid. After stirring continuously for 2 hours, heating was stopped, and the liquid was allowed to cool to room temperature to obtain a homogeneous, transparent eutectic solvent, which was sealed and stored for later use.

[0020] S002: Preparation of pH-responsive microcapsule corrosion inhibitors In this embodiment, microcapsules with polyacrylic acid (PAA) as the wall material and benzotriazole (BTA) as the core were prepared by emulsification solvent evaporation method.

[0021] Oil phase preparation: Weigh 5 g of polyacrylic acid and 3 g of benzotriazole, dissolve them together in 50 mL of dichloromethane, and sonicate for 5 minutes until completely dissolved to form a clear oil phase solution.

[0022] Aqueous phase preparation: Dissolve 1 gram of polyvinyl alcohol (emulsifier) ​​in 200 ml of deionized water, heat to 50°C and stir until completely dissolved, then cool to room temperature to obtain the aqueous phase.

[0023] Emulsification: Under the action of a high-speed shear emulsifier (8000 rpm), the oil phase is slowly added dropwise to the water phase, and shear emulsification is continued for 10 minutes to form a stable oil-in-water (O / W) emulsion.

[0024] Solvent evaporation and curing: The emulsion was transferred to a round-bottom flask and stirred continuously at 400 rpm for 4 hours at room temperature to allow the dichloromethane to fully evaporate. As the organic solvent evaporated, the wall material PAA precipitated at the oil-water interface, encapsulating the core BTA to form microcapsules.

[0025] Post-processing: The solidified microcapsule suspension was centrifuged (5000 rpm, 10 minutes), the supernatant was discarded, and the precipitate was washed three times with deionized water to remove unencapsulated drug and residual emulsifier. The washed microcapsules were then dried in a vacuum drying oven at 40°C for 12 hours to obtain a white powdery pH-responsive microcapsule corrosion inhibitor with a particle size distribution between 0.5 and 5 micrometers.

[0026] S003: Mixing and Homogenization Mix 45 parts of the eutectic solvent obtained in step S001 with 30 parts of deionized water, place the mixture in a reaction vessel, heat to 40°C, and start stirring (400 rpm). After the mixture is homogeneous, add 18 parts of the composite surfactant (i.e., alkyl glycosides and...) that have been pre-mixed in a 4:1 weight ratio. Add 8 parts of sodium alkenyl sulfonate and 8 parts of tetrasodium glutamate diacetate, a chelating detergent. Continue stirring for 20 minutes to ensure all components are completely dissolved and a homogeneous mixture is formed. Then, adjust the pH of the mixture to 10.0 using a 30% potassium hydroxide solution. At this point, the detergent is a homogeneous and transparent liquid.

[0027] S004: Introducing a sustained-release system Ten portions of the pH-responsive microcapsule corrosion inhibitor obtained in step S002 were slowly added to the mixture obtained in step S003. The mixture was stirred and dispersed at 500 rpm for 20 minutes. The microcapsules were observed to be uniformly suspended in the system without any precipitation or aggregation, thus obtaining the environmentally friendly stainless steel cleaning agent described in Example 1.

[0028] Example 2

[0029] The difference between this embodiment and Example 1 lies in the composition of the eutectic solvent and the proportion of the composite surfactant, which aims to verify the compatibility of different DES and surfactant systems.

[0030] The cleaning agent components in this embodiment are as follows: the eutectic solvent is choline chloride-ethylene glycol (molar ratio 1:3), with a dosage of 50 parts; the composite surfactant is fatty alcohol polyoxyethylene ether (AEO-9) and sodium cocoyl methyl taurate compounded at a weight ratio of 5:1, with a dosage of 20 parts; the pH-responsive microcapsule corrosion inhibitor is chitosan wall material encapsulating methylbenzotriazole, with a dosage of 8 parts; the chelating detergent is tetrasodium iminodisuccinate, with a dosage of 6 parts; and deionized water is added to bring the total to 100 parts.

[0031] Preparation method: In step S001, choline chloride and ethylene glycol are mixed at a molar ratio of 1:3 and heated and stirred at 70°C for 1.5 hours to obtain uniform and transparent DES.

[0032] In step S002, chitosan was used as the wall material. Chitosan was dissolved in a 1% aqueous acetic acid solution as the aqueous phase (wall material solution), and methylbenzotriazole was dissolved in ethyl acetate as the oil phase (capsule core solution). A water-in-oil emulsion was formed by high-speed shear emulsification, followed by microcapsule preparation via spray drying. Spray drying conditions: inlet air temperature 120℃, outlet air temperature 65℃, feed rate 10 mL / min, yielding microcapsules with a particle size of 1-4 micrometers.

[0033] In step S003, adjust the pH to 9.5.

[0034] In step S004, the stirring and dispersion conditions are 600 rpm for 15 minutes to obtain the cleaning agent of Example 2.

[0035] Example 3

[0036] The difference between this embodiment and Embodiment 1 lies in the wall material and core of the pH-responsive microcapsule corrosion inhibitor, as well as the different ratios of the eutectic solvent and the chelating detergent, which aims to optimize the release performance and synergistic detergency of the corrosion inhibitor.

[0037] The cleaning agent components in this embodiment are: a eutectic solvent of betaine-citric acid (molar ratio 1:2) in an amount of 55 parts; and a composite surfactant of alkyl glycosides and... Sodium alkenyl sulfonate is compounded at a weight ratio of 3:1, with a dosage of 15 parts; pH-responsive microcapsule corrosion inhibitor is 2-mercaptobenzothiazole encapsulated in acrylic-methacrylic acid copolymer wall material, with a dosage of 12 parts; chelating detergent is tetrasodium glutamate diacetate, with a dosage of 5 parts; deionized water is added to bring the total to 100 parts.

[0038] Preparation method: In step S001, betaine and citric acid are mixed in a 1:2 molar ratio and heated and stirred at 90°C for 3 hours to obtain a uniform and transparent DES.

[0039] In step S002, acrylic acid-methacrylic acid copolymer (molar ratio 70:30) was used as the wall material, and 2-mercaptobenzothiazole was used as the core. The preparation method was the same as the emulsification solvent evaporation method in Example 1, except that ethyl acetate was used instead of dichloromethane as the solvent. Microcapsules with an average particle size of 2.2 micrometers were obtained.

[0040] In step S003, adjust the pH to 9.8.

[0041] In step S004, the stirring and dispersion conditions are 400 rpm for 25 minutes to obtain the cleaning agent of Example 3.

[0042] Example 4

[0043] The difference between this embodiment and Example 1 lies in the molar ratio of hydrogen bond donors to hydrogen bond acceptors and the total amount of composite surfactant in the eutectic solvent, aiming to investigate the effect of different DES polarities on the cleaning effect.

[0044] The cleaning agent components of this embodiment are as follows: the eutectic solvent is tetrabutylammonium bromide-glycerol (molar ratio 1:4), with a dosage of 40 parts; the composite surfactant is fatty alcohol polyoxyethylene ether and sodium cocoyl methyl taurate compounded in a weight ratio of 4:1, with a dosage of 22 parts; the pH-responsive microcapsule corrosion inhibitor is the same as in Example 1 (polyacrylic acid wall material encapsulated with benzotriazole), with a dosage of 14 parts; the chelating detergent is tetrasodium iminodisuccinate, with a dosage of 10 parts; and deionized water is added to make up to 100 parts.

[0045] Preparation method: In step S001, tetrabutylammonium bromide and glycerol are mixed at a molar ratio of 1:4 and heated and stirred at 100°C for 4 hours to obtain uniform and transparent DES.

[0046] In step S002, the same applies as in Example 1.

[0047] In step S003, adjust the pH to 10.5.

[0048] In step S004, the stirring and dispersion conditions are 700 rpm for 10 minutes to obtain the cleaning agent of Example 4.

[0049] Comparative Example 1 This comparative example provides a cleaning agent without pH-responsive microcapsule corrosion inhibitors to compare and verify the corrosion inhibition effect and pH-responsive release characteristics of microcapsule corrosion inhibitors. Its composition is basically the same as in Example 1, except that pH-responsive microcapsule corrosion inhibitors are not added; instead, an equal amount of deionized water is used.

[0050] Comparative Example 2 This comparative example provides a cleaning agent without eutectic solvents to compare and verify the synergistic cleaning effect of DES. Its composition is basically the same as that of Example 1, except that no eutectic solvent is added, and instead an equal amount of deionized water is used.

[0051] Comparative Example 3 This comparative example provides a cleaning agent containing a non-microencapsulated free benzotriazole corrosion inhibitor to compare and verify the improvement of microencapsulation on the storage stability and on-demand release characteristics of the corrosion inhibitor. Its composition is basically the same as in Example 1, except that 10 parts of pH-responsive microencapsulated corrosion inhibitor are replaced with 0.8 parts of free benzotriazole (equivalent to the effective content in the core of the microcapsule) and 9.2 parts of deionized water to maintain a consistent total amount of active ingredients in the corrosion inhibitor.

[0052] Performance testing and effect evaluation To verify the various properties of the environmentally friendly stainless steel cleaning agent provided by the present invention, a series of tests were conducted on the cleaning agent samples of Examples 1-4 and Comparative Examples 1-3 above. All test results are summarized in Table 2.

[0053] 1. Basic physicochemical properties test Appearance stability: The appearance of the sample was observed at 25℃, and its stability was observed after being placed in constant temperature ovens at -5℃ and 50℃ for 48 hours respectively.

[0054] Surface tension: The surface tension of the cleaning agent was determined at 25°C using the platinum plate method.

[0055] pH value: The pH value of the cleaning agent concentrate was measured using a pH meter at 25°C.

[0056] 2. Detergent removal ability test 304 stainless steel plates were used as test substrates, with artificial oil stains (composed of 5% vegetable oil, 5% mineral oil, 3% dust, and 87% industrial petroleum jelly) applied to the surface. The coated stainless steel plates were aged at room temperature for 24 hours. The test pieces were immersed in the cleaning agents (diluted to 5% working solution) of Examples 1-4 and Comparative Examples 1-3, respectively, and cleaned at 50°C for 10 minutes. They were then removed, rinsed with deionized water, dried, and weighed to calculate the removal rate. Removal rate = (Weight of oil stains before cleaning - Weight of residual oil stains after cleaning) / Weight of oil stains before cleaning × 100%.

[0057] 3. Corrosion performance test Following GB / T 10124-1988 "Metallic Materials - Laboratory Uniform Corrosion Immersion Test Method", corrosion rate tests were conducted using 304 stainless steel specimens. The specimens were completely immersed in the undiluted cleaning agents of Examples 1-4 and Comparative Examples 1-3, and continuously immersed in a 50°C constant temperature water bath for 4 hours. After the test, the specimens were removed, corrosion products were cleaned, dried, weighed, and the corrosion rate was calculated.

[0058] 4. Corrosion inhibitor release behavior test To verify the pH response characteristics of the microcapsules, the cleaning agents of each example and comparative example were diluted with deionized water to 10 times their volume, and the pH values ​​were adjusted to 10.0 and 7.0, respectively. After standing for 1 hour, the concentration of benzotriazole substances in the solution was determined by high-performance liquid chromatography (HPLC) to calculate the release rate. Release rate = (corrosion inhibitor content in solution / total corrosion inhibitor in system) × 100%.

[0059] Test Results Summary

[0060] Results Analysis The test results show that: 1. Appearance and stability: All examples maintained a uniform, transparent and stable state under normal temperature and high and low temperature conditions, while Comparative Example 3 showed precipitation or stratification under extreme conditions, indicating that microencapsulation significantly improved the storage stability of the corrosion inhibitor in the alkaline cleaning system.

[0061] 2. Surface Tension and Detergent Power: The surface tensions of Examples 1 to 4 were all between 25 and 35 mN / m, exhibiting excellent wetting properties. Their detergency on 304 stainless steel was all above 96%, significantly better than Comparative Example 2 (82.4%) which did not contain DES. This demonstrates the crucial role of the synergistic effect of the eutectic solvent and the chelating detergent in disrupting the interface structure of oil stains and enhancing detergency.

[0062] 3. Corrosion Performance: The corrosion rates of 304 stainless steel in Examples 1 to 4 were all below 0.005 mm / a, far exceeding the expected target. Comparative Example 1 (without corrosion inhibitor) showed a corrosion rate as high as 0.13 mm / a, indicating that the cleaning agent had a significant corrosive effect on stainless steel even without corrosion inhibitor. Comparative Example 3 (with free corrosion inhibitor) had a corrosion rate of 0.014 mm / a, higher than the examples, indicating that the free corrosion inhibitor was partially deactivated in a strongly alkaline environment, resulting in a decreased protective effect.

[0063] 4. Corrosion Inhibitor Release Behavior: Examples 1 to 4 showed extremely low release rates (<1%) under storage conditions at pH=10.0, but significantly increased release rates (>85%) in the cleaning microenvironment at pH=7.0, achieving precise on-demand release. The free corrosion inhibitor in Comparative Example 3 was completely released under all pH conditions, exhibiting no intelligent response characteristics.

[0064] In summary, this invention constructs an environmentally friendly cleaning system using a biodegradable eutectic solvent, a chelating detergent, and a composite surfactant. It also utilizes a pH-responsive microcapsule corrosion inhibitor to achieve an intelligent controlled-release mechanism where the inhibitor remains inert during storage and is released on demand as the pH level decreases in the micro-regions during cleaning. Furthermore, the eutectic solvent, pH-responsive microcapsule corrosion inhibitor, and chelating detergent form a synergistic system, significantly enhancing detergency while precisely controlling corrosion behavior. Ultimately, this achieves a balance between high-efficiency cleaning and low corrosion, resulting in a cleaning agent with comprehensive properties such as low surface tension, strong wetting and penetration, and extremely low corrosion rate on stainless steel substrates.

[0065] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An environmentally friendly stainless steel cleaning agent, characterized in that, The cleaning agent is a homogeneous and transparent liquid, comprising the following components by weight: 30-60 parts of eutectic solvent, 10-25 parts of composite surfactant, 5-15 parts of pH-responsive microcapsule corrosion inhibitor, 5-12 parts of chelating detergent, and the balance being deionized water. The eutectic solvent is prepared by heating and stirring a hydrogen bond donor and a hydrogen bond acceptor in a molar ratio of 1:1 to 4:

1. The pH-responsive microcapsule corrosion inhibitor is a microcapsule structure prepared with a pH-sensitive polymer as the capsule wall and a benzotriazole compound or a mercaptobenzothiazole compound as the core. The microcapsule maintains the integrity of the capsule wall when the initial pH value of the cleaning solution is 9.0-11.0 to inhibit the release of the corrosion inhibitor. During the cleaning process, when the pH value of the micro-area on the stainless steel surface decreases to 6.5-7.5, the capsule wall swells or ruptures to release the corrosion inhibitor. The pH-sensitive polymer is at least one of polyacrylic acid, chitosan, or acrylic acid-methacrylic acid copolymer, and the particle size of the pH-responsive microcapsule corrosion inhibitor is 0.5-5 micrometers; The chelating detergent is tetrasodium glutamate diacetate or tetrasodium iminodisuccinate. The eutectic solvent, pH-responsive microcapsule corrosion inhibitor, and chelating detergent builder form a synergistic system. The eutectic solvent disrupts the oil stain interface structure through a hydrogen bond network, and the chelating detergent builder complexes metal ions to enhance detergency. The pH-responsive microcapsule corrosion inhibitor releases its active ingredient only during the cleaning process to inhibit corrosion. The pH-responsive microcapsule corrosion inhibitor remains inert during storage. The release condition of the pH-responsive microcapsule corrosion inhibitor is: the active ingredient is released when the synergistic effect of the eutectic solvent and the chelating cleaning aid causes the micro-area of ​​the stainless steel surface to acidify to 6.5-7.

5.

2. The environmentally friendly stainless steel cleaning agent according to claim 1, characterized in that, The hydrogen bond donor is selected from one or more of urea, ethylene glycol, glycerol, citric acid, malic acid, or oxalic acid, and the hydrogen bond acceptor is selected from one or more of choline chloride, betaine, or tetrabutylammonium bromide.

3. The environmentally friendly stainless steel cleaning agent according to claim 1, characterized in that, The composite surfactant is formulated by compounding a nonionic surfactant and an anionic surfactant in a weight ratio of 3:1 to 5:

1. The nonionic surfactant is an alkyl glycoside and / or fatty alcohol polyoxyethylene ether, and the anionic surfactant is... Sodium alkenyl sulfonate and / or sodium cocoyl methyl taurate.

4. The environmentally friendly stainless steel cleaning agent according to claim 1, characterized in that, The core is one or more of benzotriazole, methylbenzotriazole or 2-mercaptobenzothiazole.

5. The environmentally friendly stainless steel cleaning agent according to claim 1, characterized in that, The surface tension of the cleaning agent at 25°C is 25-35 mN / m, and the corrosion rate of the cleaning agent on 304 or 316L stainless steel substrates after immersion at 50°C for 4 hours is less than 0.01 mm / a.

6. The environmentally friendly stainless steel cleaning agent according to claim 1, characterized in that, The mass ratio of the eutectic solvent to the chelating detergent is 3:1 to 10:1, and the molar ratio of hydrogen bond donor to hydrogen bond acceptor in the eutectic solvent is 2:1 to 3:

1.

7. A method for preparing an environmentally friendly stainless steel cleaning agent according to any one of claims 1-6, characterized in that, Includes the following steps: S001: Preparation of eutectic solvent: Mix hydrogen bond donor and hydrogen bond acceptor at a preset molar ratio, heat and stir at 60-100℃ for 1-4 hours until a homogeneous and transparent eutectic solvent is formed, and cool for later use. S002: Preparation of pH-responsive microcapsule corrosion inhibitors: pH-sensitive polymers are dissolved in organic solvents or aqueous phases as wall material solutions, and corrosion inhibitor cores are mixed with the wall material solutions. pH-responsive microcapsule corrosion inhibitors with a particle size range of 0.5-5 micrometers are prepared by emulsification solvent evaporation method or spray drying method. S003: Mixing and homogenization: Mix the eutectic solvent obtained in step S001 with deionized water, stir at 30-50℃, then add the composite surfactant and chelated detergent in sequence, continue stirring until completely dissolved to form a mixture, and adjust the pH to 9.0-10.

5. S004: Introducing a sustained-release system: The pH-responsive microcapsule corrosion inhibitor obtained in step S002 is added to the mixture obtained in step S003, and stirred and dispersed at a speed of 300-800 rpm for 10-30 minutes until the microcapsules are uniformly suspended to obtain the environmentally friendly stainless steel cleaning agent.

8. The preparation method according to claim 7, characterized in that, In step S002, pH-responsive microcapsule corrosion inhibitors are prepared using an emulsification solvent evaporation method. Specifically, the pH-sensitive polymer and the corrosion inhibitor core are dissolved together in dichloromethane or ethyl acetate as the oil phase. The oil phase is added to an aqueous phase containing an emulsifier, and high-speed shear emulsification is performed to form an oil-in-water emulsion. The organic solvent is then evaporated by stirring. After washing and drying, microcapsules are obtained.

9. The preparation method according to claim 7, characterized in that, In step S003, the pH adjuster is one or more of citric acid, triethanolamine, or potassium hydroxide. The adjusted pH value ensures that the pH-responsive microcapsule corrosion inhibitor maintains the integrity of the capsule wall during storage.

Images