Liquid high-efficiency environment-friendly metal degreasing agent and preparation method thereof

Abstract

A highly efficient and environmentally friendly liquid metal degreasing agent and its preparation method are disclosed, belonging to the field of metal surface treatment technology. This degreasing agent is composed of a pH adjuster (a mixture of aminosulfonic acid and citric acid), a composite surfactant (a mixture of nonionic and anionic surfactants), a phosphorus-free chelating agent, a composite corrosion inhibitor, a defoamer, a detergent builder, and deionized water in specific weight proportions. The preparation method involves sequentially dissolving and mixing each component. This invention achieves highly efficient synergistic degreasing and rust removal under weakly acidic conditions. At room temperature, it provides excellent cleaning and corrosion protection for various metal substrates such as steel, aluminum alloys, and galvanized sheets. It is free of strong acids, phosphates, and heavy metals, making it environmentally friendly, safe, low-foaming, and stable. It is particularly suitable for automated spray production lines, comprehensively solving the problem of simultaneously achieving effective cleaning, substrate protection, and environmental protection requirements in existing technologies.

Description

Technical Field

[0001] A highly efficient and environmentally friendly liquid metal degreasing agent and its preparation method are disclosed, belonging to the field of metal surface treatment technology. Background Technology

[0002] In industries such as metal processing, coating, and electroplating, pretreatment of metal substrates to remove oil, rust, and scale is a crucial step in ensuring the final quality and performance of products. Degreasing agents, as the core chemicals in this process, directly determine the cleaning effect, production efficiency, environmental compliance, and overall cost.

[0003] Traditional metal degreasing agents have evolved through technological advancements, primarily from alkaline degreasing agents to solvent-based degreasing agents and finally to water-based degreasing agents. Alkaline degreasing agents rely on strong alkalis and additives such as silicates and phosphates. While effective at saponifying animal and vegetable oils, they have limited cleaning power for mineral oils and are prone to scale formation in hard water conditions, making rinsing difficult. Their high alkalinity also poses a risk of corrosion to amphoteric metals such as aluminum and zinc. Solvent-based degreasing agents (such as chlorinated hydrocarbons and gasoline) have strong oil-dissolving power, but they present safety and environmental challenges due to high emissions of volatile organic compounds (VOCs), high toxicity, and flammability / explosiveness, leading to increasingly limited applications. Currently, water-based composite degreasing agents, primarily acidic or weakly acidic, have become the mainstream development direction in the market due to their safe operation and high efficiency.

[0004] However, existing technologies, especially commercially available acidic and environmentally friendly water-based degreasers, still face a series of mutually restrictive technical bottlenecks in the pursuit of high performance and environmental compatibility. They fail to adequately meet the comprehensive needs of modern industry for "high efficiency, environmental friendliness, gentleness, and economy," specifically manifested in the following ways: 1. Poor environmental performance: Most products use volatile strong acids such as hydrochloric acid and hydrofluoric acid, and add toxic additives such as phosphates and chromates. The phosphorus-containing and heavy metal-containing waste liquids can easily cause environmental pollution and do not meet environmental emission requirements.

[0005] 2. Poor synergy between degreasing and rust removal: The strong acid system has a weak emulsification ability for heavy oil stains, often resulting in "rust removal without oil removal, and incomplete oil removal", requiring multiple steps for processing, resulting in low production efficiency.

[0006] 3. Insufficient substrate protection can easily lead to corrosion damage: Traditional acidic degreasing agents have high acidity and simple corrosion inhibition systems, which can easily cause problems such as over-corrosion, pitting, discoloration, and hydrogen embrittlement on sensitive metals such as aluminum alloys, galvanized sheets, and copper, affecting the precision and appearance of the workpiece.

[0007] 4. Insufficient stability and applicability: Some products produce high levels of foam and are not suitable for spray lines; the working fluid is easily contaminated by metal ions and becomes ineffective, resulting in a short service life; the cleaning efficiency decreases significantly under low temperature conditions, requiring heating and resulting in high energy consumption.

[0008] 5. High difficulty in waste liquid treatment: Strong acid, phosphorus-containing, and heavy metal-containing waste liquids require complex neutralization and precipitation treatment, which is costly and can easily cause secondary pollution.

[0009] Existing environmentally friendly acidic degreasing agents still suffer from problems such as low degreasing efficiency, poor corrosion inhibition, weak low-temperature performance, and poor foam control, making it difficult to simultaneously meet the comprehensive requirements of high efficiency, environmental protection, low corrosion, and low foam stability. Summary of the Invention

[0010] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a liquid high-efficiency and environmentally friendly metal degreasing agent and its preparation method that can efficiently and synergistically remove various oil stains and rust at room temperature, is safe and non-corrosive to various metal substrates, does not contain harmful substances, is low-foaming and stable, and is suitable for various cleaning processes such as spraying.

[0011] The technical solution adopted by the present invention to solve its technical problem is: a liquid high-efficiency and environmentally friendly metal degreasing agent, characterized in that it is composed of the following components in parts by weight: 10-20 parts of acid-base regulator; 8-15 parts of composite surfactant; 3-6 parts of chelating agent; 1-3 parts of corrosion inhibitor; 0.5-1.5 parts of defoamer; 2-4 parts of detergent builder; and 50-65 parts of deionized water.

[0012] This formulation system achieves a perfect balance of degreasing, rust removal, corrosion inhibition, defoaming, and environmental performance through the scientific ratio and synergistic effect of its components. Specifically, 10-20 parts of an acid-base regulator provide a moderate and stable acidic environment, effectively dissolving metal oxides while preventing excessive corrosion of the substrate by strong acids. 8-15 parts of a composite surfactant ensure excellent penetration, emulsification, and oil dispersion capabilities. 3-6 parts of a chelating agent effectively complexes metal ions dissolved during cleaning, preventing secondary deposition and extending the working fluid's lifespan. 1-3 parts of a corrosion inhibitor form a protective film on the metal surface, effectively protecting various metals in an acidic environment. 0.5-1.5 parts of a defoamer ensure low-foaming characteristics in the spraying process. 2-4 parts of a detergent enhance cleaning effectiveness and improve rinsing properties. Using 50-65 parts of deionized water as the medium ensures full dissolution and stable dispersion of all components, ultimately resulting in a highly efficient, environmentally friendly, low-corrosion, and highly adaptable integrated pretreatment product.

[0013] Specifically, the acid-base regulator is a compound of aminosulfonic acid and an organic acid. Using a compound of aminosulfonic acid and an organic acid as an acid-base regulator has significant advantages compared to using a single strong acid (such as hydrochloric acid or sulfuric acid). Aminosulfonic acid has moderate acidity, a strong ability to dissolve rust products, and the resulting salts have high solubility and are less prone to precipitation. The addition of the organic acid further adjusts and stabilizes the pH value of the system, and its chelating effect helps dissolve and disperse metal ions. The combination of the two produces a synergistic effect, making the acidity of the system milder and more stable, ensuring rust removal speed while significantly reducing the risk of corrosion to the metal substrate, and avoiding the safety and environmental problems associated with using volatile strong acids.

[0014] Preferably, the organic acid is citric acid; the mass ratio of aminosulfonic acid to citric acid is 2-4:1. Citric acid is preferred as the organic acid component because of its excellent chelating properties and safe and environmentally friendly characteristics. At this ratio, aminosulfonic acid provides the main rust-removing power, quickly dissolving the oxide scale; citric acid acts as a buffer and auxiliary chelating agent, stabilizing the pH of the working solution, preventing excessively high local acidity, and effectively chelating free Fe in the solution. 3+ Ca 2+ Mg 2+ Plasma prevents the formation of insoluble soap scum or secondary deposition on the workpiece surface, thereby improving the thoroughness of rust removal while further protecting the substrate and extending the service life of the degreaser.

[0015] Specifically, the composite surfactant includes nonionic and anionic surfactants. The strategy of combining nonionic and anionic surfactants fully leverages their synergistic effect in the degreasing process. Nonionic surfactants maintain good activity at low temperatures, exhibiting good cleaning effects on mineral oils and animal and vegetable oils with low foaming. Anionic surfactants possess excellent wetting, dispersing, and anti-redeposition properties, stably dispersing the removed oil particles in the solution and preventing their re-adhesion. The combined effect at both the oil-water and metal-solution interfaces significantly reduces interfacial tension, making the degreasing process faster and more thorough, achieving highly efficient integrated removal of complex oil contaminants.

[0016] Preferably, the mass ratio of the nonionic surfactant to the anionic surfactant is 2-5:1. Within this range, the nonionic surfactant dominates, ensuring excellent emulsifying and degreasing capabilities and good low-temperature performance, while maintaining low foaming properties, meeting the requirements of spray cleaning processes. The addition of an appropriate amount of anionic surfactant enhances the wetting speed and dispersion stability of the formulation, compensating for the shortcomings of nonionic surfactants in hard water resistance and anti-fouling redeposition. This preferred ratio achieves an optimal balance between high efficiency, low foaming, and stability in the composite surfactant system, making it suitable for various cleaning methods from immersion to spraying.

[0017] More preferably, the nonionic surfactant is a compound of isotretinoin polyoxyethylene polyoxypropylene ether and alkyl glycoside, and the anionic surfactant is sodium dodecylbenzenesulfonate. Isotretinoin polyoxyethylene polyoxypropylene ether is a low-foaming, high-penetration nonionic surfactant. Its unique branched structure and block polyether chain endow it with excellent wetting, penetrating, and emulsifying abilities for mineral oils. Alkyl glycoside (APG) is a naturally derived, green nonionic surfactant with good biodegradability, gentleness on the skin, strong emulsifying power for animal and vegetable oils, and can produce good synergistic effects with nonionic / anionic surfactants to improve overall degreasing efficiency. The preferred anionic surfactant is sodium dodecylbenzenesulfonate (LAS), which is an inexpensive, highly efficient, and strong degreasing anionic surfactant that can effectively disperse solid dirt and stripped oil. The specific combination of the three, at the stated ratio, achieves a balance between efficient degreasing, excellent low-temperature stability, low-foaming characteristics, and good environmental compatibility.

[0018] Preferably, the chelating agent is a compound of sodium gluconate and hydroxyethylidene diphosphonic acid (HEDP) in a mass ratio of 1 to 2:1. Sodium gluconate is a polyhydroxycarboxylate with excellent chelating ability for alkaline earth metal ions such as calcium and magnesium, and it is also biodegradable. HEDP is an organophosphonic acid corrosion and scale inhibitor with extremely strong chelating ability for various metal ions such as iron, calcium, copper, and zinc. When combined, their effects are complementary: sodium gluconate focuses on chelating hard water ions to prevent scale buildup; HEDP effectively blocks heavy metal ions such as iron and zinc dissolved from the workpiece. This phosphorus-free or low-phosphorus (HEDP contains phosphorus but is an environmentally friendly organophosphorus) chelating system not only stabilizes the working fluid and prevents performance degradation and workpiece surface "dust" caused by metal ion contamination, but also significantly reduces the difficulty of wastewater treatment and the eutrophication impact on the environment.

[0019] Preferably, the corrosion inhibitor is a compound of imidazoline corrosion inhibitor and lignin sulfonate, with a mass ratio of 1 to 3:1. Imidazolyl corrosion inhibitors are highly efficient adsorption film-type corrosion inhibitors; the polar groups in their molecules can be tightly adsorbed onto the metal surface to form a monomolecular protective film, effectively inhibiting H₂ corrosion.+ This process inhibits the discharge corrosion of metals, preventing hydrogen embrittlement and excessive corrosion. Lignosulfonate is a natural polymer compound that, in addition to its dispersing properties, can form a protective film on metal surfaces and exhibits good corrosion inhibition effects on amphoteric metals such as aluminum and zinc. By combining the two in a mass ratio of 1 to 3:1, imidazoline acts as the primary corrosion inhibitor, providing strong cathodic inhibition, while lignosulfonate serves as an auxiliary corrosion inhibitor and dispersant. This broadens the corrosion inhibition spectrum, allowing the degreaser to be safely used on various metals such as carbon steel, alloy steel, aluminum alloys, and galvanized sheets, achieving "one agent for multiple uses" and avoiding the hassle of changing degreasers due to different metal materials.

[0020] Preferably, the defoamer is a polyether-modified siloxane defoamer. This type of defoamer combines the water solubility of the polyether segment with the low surface tension of the organosilicon segment, allowing it to spread rapidly in acidic aqueous systems, disrupting the elasticity of the foam film and thus achieving efficient and long-lasting defoaming and foam suppression effects. This ensures that the degreaser maintains a low-foaming state throughout the process of vigorous mechanical stirring or spray cleaning.

[0021] Preferably, the cleaning aid is a compound of urea and a phosphate-free cleaning aid. Urea acts not only as a pH buffer but also, more importantly, due to its excellent penetration and hydration capabilities, helps the degreasing solution quickly penetrate to the interface between oil and metal, loosening and breaking down stubborn oil stains, particularly beneficial for removing viscous contaminants such as polishing paste and stretching oil. The phosphate-free cleaning aid replaces traditional phosphates, primarily functioning to disperse dirt particles, soften water, and provide a certain alkaline reserve to maintain pH stability during the cleaning process. This compound cleaning aid system enhances the cleaning effect while completely eliminating the introduction of phosphorus, achieving "phosphate-free" production from the source, significantly reducing the burden on wastewater treatment and the risk of eutrophication of water bodies.

[0022] The pH value of the aforementioned liquid high-efficiency and environmentally friendly metal degreasing agent is 1.5~3.0. The formulation of this invention stabilizes the pH within this optimized range through the synergistic effect of its components. At this pH, sufficient dissolution kinetics for common rusts are ensured, while the preferred non-phosphorus corrosion inhibitor system exerts its best protective efficacy. Simultaneously, acid mist emission is minimized, improving the working environment and achieving a balance between efficient cleaning and safe operation.

[0023] A method for preparing the above-mentioned liquid high-efficiency and environmentally friendly metal degreasing agent, characterized by comprising the following steps: (1) Weigh each raw material according to the proportions; (2) Add deionized water to the reactor and stir for 5-10 minutes; (3) Add acid-base regulator and stir until completely dissolved; (4) Add chelating agent and washing aid, and stir for 10-15 minutes; (5) Add the composite surfactant and stir for 20-25 minutes until homogeneous; (6) Finally, add corrosion inhibitor and defoamer, stir for 10 min to 15 min to obtain the finished product.

[0024] This preparation method is simple, operates under mild conditions, and is easy to industrialize. First, most of the deionized water is added and initial stirring is provided to create a medium for subsequent dissolution. An acid-base regulator is added first to quickly establish an acidic environment, which is beneficial for the dissolution and stability of subsequent components. Then, chelating agents and detergent builders are added to ensure complete dissolution in the acidic medium and to provide initial integration and buffering effects. After the acidic system and additives are established, a composite surfactant, which is relatively sensitive to pH and ionic strength, is added. Prolonged stirring ensures its full dispersion and the formation of a stable micelle structure. Finally, corrosion inhibitors and defoamers are added to prevent potential performance degradation under strong acid or high shear conditions, ensuring their functionality is fully preserved in the final product. The entire process can be carried out at room temperature or low temperature, requiring no heating, making it energy-efficient and environmentally friendly. By controlling the stirring time at each step, complete dissolution and sufficient reaction of all components are ensured, resulting in a homogeneous, stable, and reliable liquid degreasing agent product.

[0025] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention provides a mild yet highly efficient acidic environment through the compounding of aminosulfonic acid and citric acid, achieves powerful degreasing through the compounding of nonionic and anionic surfactants in a specific ratio, and utilizes a phosphorus-free chelating agent and a composite corrosion inhibitor system, thereby achieving a highly efficient synergistic effect of degreasing and rust removal. Its beneficial effects include: this degreasing agent can thoroughly clean various oil stains and rust in one step at room temperature, significantly improving efficiency and reducing energy consumption; it also provides excellent corrosion protection for various metal substrates such as steel, aluminum alloys, and galvanized sheets, avoiding the risks of over-corrosion and hydrogen embrittlement; the formula does not contain strong acids, phosphates, heavy metals, or other toxic and harmful substances, ensuring environmental protection and safety from the source; its low-foaming and stable characteristics are particularly suitable for automated spray production lines, and the working fluid has a long lifespan, comprehensively solving the industry problem of balancing cleaning effect, substrate protection, environmental requirements, and process adaptability in existing technologies. Detailed Implementation

[0026] The present invention will be further described below with reference to specific embodiments, wherein Embodiment 1 is the preferred embodiment of the present invention, and the process conditions in the other embodiments are the same as those in Embodiment 1 unless otherwise specified. Example 1

[0027] The specific composition, by weight, is as follows: A compound of aminosulfonic acid and citric acid is used as an acid-base regulator, with a total amount of 15 parts, of which aminosulfonic acid accounts for 11.25 parts and citric acid for 3.75 parts, with a mass ratio of 3:1; the total amount of the composite surfactant is 12 parts, composed of 8.6 parts nonionic surfactant and 3.4 parts anionic surfactant, with a mass ratio of approximately 2.5:1, of which the nonionic surfactant consists of 6 parts isomeric tridecyl alcohol polyoxyethylene polyoxypropylene ether and 2.6 parts alkyl glycoside, and the anionic surfactant... The surfactant consists of 3.4 parts sodium dodecylbenzenesulfonate; the total amount of chelating agent is 5 parts, which is a mixture of equal mass of sodium gluconate and hydroxyethylidene diphosphonic acid in a 1:1 mass ratio; the total amount of corrosion inhibitor is 2.5 parts, which is a mixture of 1.7 parts imidazoline corrosion inhibitor and 0.8 parts lignin sulfonate in a mass ratio of approximately 2:1; the defoamer is 1.0 part polyether-modified siloxane defoamer; the total amount of detergent builder is 3 parts, which is a mixture of 2 parts urea and 1 part phosphate-free detergent builder sodium polyacrylate; the remainder is deionized water, with a total amount of 60.9 parts.

[0028] The preparation method includes the following steps: First, accurately weigh each raw material according to the above proportions at room temperature. Then, add all deionized water to a reactor equipped with a stirrer and temperature control device, and stir at 200 r / min to 300 r / min for 5 minutes to ensure uniform mixing. While continuously stirring, slowly add the weighed aminosulfonic acid and citric acid, controlling the material temperature during the addition process to not exceed 40°C. After the addition is complete, continue stirring until the solids are completely dissolved, forming a clear acidic solution. Then, while maintaining stirring, add sodium gluconate, HEDP, urea, and sodium polyacrylate sequentially, maintaining the stirring speed at 200 r / min to 300 r / min and stirring continuously for 15 minutes to ensure that each component is fully dissolved and mixed. Next, while stirring, slowly add isotridecyl alcohol polyoxyethylene polyoxypropylene ether, alkyl glycoside, and sodium dodecylbenzene sulfonate. After the addition is complete, increase the stirring speed to 300 r / min to 40 r / min and stir vigorously for 25 minutes until a homogeneous, transparent, and non-layered solution system is formed. Finally, while stirring, add the imidazoline corrosion inhibitor, lignin sulfonate, and polyether-modified siloxane defoamer. Adjust the stirring speed back to 200-300 rpm and continue stirring for 15 minutes to ensure all components are evenly dispersed. Stop stirring. The resulting product has a pH of 2.2. After filtration, it can be packaged to obtain the finished liquid high-efficiency and environmentally friendly metal degreasing agent. Example 2

[0029] The specific composition, by weight, is as follows: A compound of aminosulfonic acid and citric acid is used as an acid-base regulator, with a total amount of 10 parts, of which aminosulfonic acid accounts for 6.67 parts and citric acid for 3.33 parts, with a mass ratio of 2:1; the total amount of the composite surfactant is 8 parts, composed of 5.33 parts nonionic surfactant and 2.67 parts anionic surfactant, with a mass ratio of 2:1, of which the nonionic surfactant consists of 4 parts isomeric tridecyl alcohol polyoxyethylene polyoxypropylene ether and 1.33 parts alkyl glycoside, and the anionic surfactant is... 2.67 parts sodium dodecylbenzenesulfonate; the total amount of chelating agent is 3 parts, which is a mixture of 1.5 parts sodium gluconate and 1.5 parts hydroxyethylidene diphosphonic acid in a 1:1 mass ratio; the total amount of corrosion inhibitor is 1 part, which is a mixture of 0.67 parts imidazoline corrosion inhibitor and 0.33 parts lignin sulfonate in a mass ratio of approximately 2:1; the defoamer is 0.5 parts polyether-modified siloxane defoamer; the total amount of detergent is 2 parts, which is a mixture of 1.3 parts urea and 0.7 parts phosphate-free detergent sodium polyacrylate; the remainder is deionized water, with a total amount of 74.5 parts.

[0030] The preparation method includes the following steps: At room temperature, all deionized water is added to the reactor and stirred at 250 r / min for 5 min; then, aminosulfonic acid and citric acid are slowly added, controlling the temperature not to exceed 40℃, and stirred until completely dissolved; then, sodium gluconate, HEDP, urea and sodium polyacrylate are added sequentially, maintaining the stirring speed at 250 r / min and stirring for 10 min; then, isotridecyl alcohol polyoxyethylene polyoxypropylene ether, alkyl glycoside and sodium dodecylbenzene sulfonate are slowly added, and after the addition is complete, the stirring speed is increased to 350 r / min and stirred vigorously for 20 min; finally, imidazoline corrosion inhibitor, lignin sulfonate and defoamer are added, the stirring speed is adjusted back to 250 r / min, and stirring is continued for 10 min. After mixing evenly, a finished product with a pH value of about 1.8 is obtained. Example 3

[0031] The specific composition, by weight, is as follows: A compound of aminosulfonic acid and citric acid is used as an acid-base regulator, with a total amount of 20 parts, of which aminosulfonic acid accounts for 16 parts and citric acid for 4 parts, with a mass ratio of 4:1; the total amount of the composite surfactant is 15 parts, composed of 12.5 parts of nonionic surfactant and 2.5 parts of anionic surfactant, with a mass ratio of 5:1, of which the nonionic surfactant consists of 9 parts of isomeric tridecyl alcohol polyoxyethylene polyoxypropylene ether and 3.5 parts of alkyl glycoside, and the anionic surfactant... The total amount of the following components is as follows: 2.5 parts sodium dodecylbenzenesulfonate; 6 parts chelating agent, which is a mixture of 2 parts sodium gluconate and 4 parts hydroxyethylidene diphosphonic acid in a 1:2 mass ratio; 3 parts corrosion inhibitor, which is a mixture of 1.5 parts imidazoline corrosion inhibitor and 1.5 parts lignosulfonate in a 1:1 mass ratio; 1.5 parts polyether-modified siloxane defoamer; 4 parts detergent builder, which is a mixture of 2.7 parts urea and 1.3 parts phosphate-free detergent builder sodium polyacrylate; and the remainder is deionized water, totaling 49.5 parts.

[0032] The preparation method includes the following steps: At room temperature, all deionized water is added to the reactor and stirred at 300 r / min for 10 min; then, aminosulfonic acid and citric acid are slowly added, controlling the temperature to not exceed 40℃, and stirred until completely dissolved; then, sodium gluconate, HEDP, urea and sodium polyacrylate are added sequentially, maintaining the stirring speed at 300 r / min and stirring for 15 min; then, isotridecyl alcohol polyoxyethylene polyoxypropylene ether, alkyl glycoside and sodium dodecylbenzene sulfonate are slowly added, and after the addition is complete, the stirring speed is increased to 400 r / min and stirred vigorously for 25 min; finally, imidazoline corrosion inhibitor, lignin sulfonate and defoamer are added, the stirring speed is adjusted back to 300 r / min, and stirring is continued for 15 min. After mixing evenly, a finished product with a pH value of about 2.5 is obtained. Example 4

[0033] The specific composition, by weight, is as follows: A compound of aminosulfonic acid and citric acid is used as an acid-base regulator, with a total amount of 12 parts, of which aminosulfonic acid accounts for 8.57 parts and citric acid for 3.43 parts, with a mass ratio of approximately 2.5:1; the total amount of the composite surfactant is 10 parts, composed of 7.5 parts nonionic surfactant and 2.5 parts anionic surfactant, with a mass ratio of 3:1, of which the nonionic surfactant consists of 5 parts isomeric tridecyl alcohol polyoxyethylene polyoxypropylene ether and 2.5 parts alkyl glycoside, and the anionic surfactant... The surfactant consists of 2.5 parts sodium dodecylbenzenesulfonate; the total amount of chelating agent is 4 parts, which is a mixture of 2.67 parts sodium gluconate and 1.33 parts hydroxyethylidene diphosphonic acid in a 2:1 mass ratio; the total amount of corrosion inhibitor is 2 parts, which is a mixture of 1 part imidazoline corrosion inhibitor and 1 part lignin sulfonate in a 1:1 mass ratio; the defoamer is 1.0 part polyether-modified siloxane defoamer; the total amount of detergent is 3 parts, which is a mixture of 2 parts urea and 1 part phosphate-free detergent sodium polyacrylate; the remainder is deionized water, amounting to 67.5 parts.

[0034] The preparation method includes the following steps: At room temperature, all deionized water is added to the reactor and stirred at 200 r / min for 8 min; then, aminosulfonic acid and citric acid are slowly added, controlling the temperature to not exceed 40℃, and stirred until completely dissolved; then, sodium gluconate, HEDP, urea and sodium polyacrylate are added sequentially, maintaining the stirring speed at 200 r / min and stirring for 12 min; then, isotridecyl alcohol polyoxyethylene polyoxypropylene ether, alkyl glycoside and sodium dodecylbenzene sulfonate are slowly added, and after the addition is complete, the stirring speed is increased to 300 r / min and stirred vigorously for 22 min; finally, imidazoline corrosion inhibitor, lignin sulfonate and defoamer are added, the stirring speed is adjusted back to 200 r / min, and stirring is continued for 12 min. After mixing evenly, a finished product with a pH value of about 2.0 is obtained. Example 5

[0035] The specific composition, by weight, is as follows: Acid-base regulator composed of sulfamic acid and citric acid, totaling 18 parts, of which sulfamic acid comprises 13.5 parts and citric acid 4.5 parts, with a mass ratio of 3:1; A composite surfactant, totaling 13 parts, is composed of 9.75 parts nonionic surfactant and 3.25 parts anionic surfactant, with a mass ratio of 3:1, of which the nonionic surfactant comprises 8 parts isomeric tridecyl alcohol polyoxyethylene polyoxypropylene ether and 1.75 parts alkyl glycoside, and the anionic surfactant comprises 3.2 parts... 5 parts sodium dodecylbenzenesulfonate; 5.5 parts chelating agent, a mixture of 2.75 parts sodium gluconate and 2.75 parts hydroxyethylidene diphosphonic acid in a 1:1 mass ratio; 1.5 parts corrosion inhibitor, a mixture of 1.0 part imidazoline corrosion inhibitor and 0.5 parts lignin sulfonate in a 2:1 mass ratio; 0.8 parts polyether-modified siloxane defoamer; 3.5 parts detergent builder, a mixture of 2.3 parts urea and 1.2 parts phosphate-free detergent builder sodium polyacrylate; the remainder is deionized water, totaling 57.45 parts.

[0036] The preparation method includes the following steps: At room temperature, all deionized water is added to the reactor and stirred at 280 r / min for 6 min; then, aminosulfonic acid and citric acid are slowly added, controlling the temperature to not exceed 40℃, and stirred until completely dissolved; then, sodium gluconate, HEDP, urea and sodium polyacrylate are added sequentially, maintaining the stirring speed at 280 r / min and stirring for 13 min; then, isotridecyl alcohol polyoxyethylene polyoxypropylene ether, alkyl glycoside and sodium dodecylbenzene sulfonate are slowly added, and after the addition is complete, the stirring speed is increased to 380 r / min and stirred vigorously for 23 min; finally, imidazoline corrosion inhibitor, lignin sulfonate and defoamer are added, the stirring speed is adjusted back to 280 r / min, and stirring is continued for 13 min. After mixing evenly, a finished product with a pH value of approximately 2.3 is obtained. Example 6

[0037] The specific composition, by weight, is as follows: the acid-base regulator is a compound of 13 parts aminosulfonic acid and 4.33 parts citric acid, with a total weight of 17.33 parts and a mass ratio of 3:1; the total amount of the composite surfactant is 14 parts, of which the mass ratio of nonionic surfactant (10 parts) to anionic surfactant (4 parts) is 2.5:1. Here, the nonionic surfactant is composed of 5 parts isomeric tridecyl alcohol polyoxyethylene polyoxypropylene ether and 5 parts alkyl glycoside to enhance the emulsifying power of animal and vegetable oils. The anionic surfactant is 4 parts sodium dodecylbenzenesulfonate; the chelating agent is 3 parts, which is a mixture of 2 parts sodium gluconate and 1 part hydroxyethylidene diphosphonic acid in a 2:1 mass ratio; the corrosion inhibitor is 2.2 parts, of which 1.47 parts are imidazoline corrosion inhibitor and 0.73 parts are lignin sulfonate in a mass ratio of approximately 2:1; the defoamer is a polyether-modified siloxane defoamer, with a dosage of 1.2 parts; the detergent builder is 3.5 parts, which is a mixture of 2.5 parts urea and 1 part sodium polyacrylate; and deionized water is added to a total of 100 parts.

[0038] The preparation process strictly follows the optimized process: First, at room temperature, metered deionized water is added to the reactor and stirred at 250 rpm for 8 minutes as initial mixing. Then, sulfamic acid and citric acid are slowly added while stirring, controlling the material temperature to never exceed 40°C. After addition, stirring continues until completely dissolved. Next, sodium gluconate, HEDP, urea, and sodium polyacrylate are added sequentially, maintaining a stirring speed of 200-300 rpm for 12 minutes. Then, isotridecyl alcohol polyoxyethylene polyoxypropylene ether, alkyl glycoside, and sodium dodecylbenzene sulfonate are slowly added. After addition, the stirring speed is increased to 350 rpm and vigorously stirred for 22 minutes to ensure sufficient dispersion of the surfactant and the formation of uniform micelles. Finally, imidazoline corrosion inhibitors, lignin sulfonate, and defoamers are added, the stirring speed is adjusted back to 250 rpm, and stirring continues for 12 minutes to ensure uniform mixing of all components, resulting in a finished product with a pH of approximately 2.1. Example 7

[0039] The specific composition by weight is as follows: The total amount of acid-base regulator is 19 parts, of which 15.2 parts are aminosulfonic acid and 3.8 parts are citric acid, with a mass ratio of 4:1; the total amount of composite surfactant is 9 parts, of which nonionic surfactant (6 parts) and anionic surfactant (3 parts) are compounded in a 2:1 ratio, wherein the nonionic component is 4 parts isotridecyl alcohol polyoxyethylene polyoxypropylene ether and 2 parts are alkyl glycosides, and the anionic component is 3 parts sodium dodecylbenzenesulfonate; the amount of chelating agent is 6 parts as specified in the upper limit of the claims, and it is compounded with sodium gluconate and HEDP in a mass ratio of 1:2, i.e., 2 parts sodium gluconate and 2 parts HEDP. 4 parts to enhance the blocking of heavy metal ions; 2.8 parts of corrosion inhibitor, compounded with imidazoline corrosion inhibitor and lignosulfonate at a mass ratio of 1.5:1, namely 1.68 parts and 1.12 parts respectively; 1.4 parts of defoamer, polyether modified siloxane defoamer; 2.2 parts of detergent builder, composed of 1.5 parts of urea and 0.7 parts of sodium polyacrylate; and 55.6 parts of deionized water.

[0040] The preparation process is as follows: Deionized water is added to a reaction vessel at room temperature and stirred at 220 rpm for 6 minutes. Then, sulfamic acid and citric acid are slowly added while stirring, with the dissolution temperature strictly controlled below 40°C. After complete dissolution, sodium gluconate, HEDP, urea, and sodium polyacrylate are added, and stirring is continued at 220 rpm for 10 minutes. Next, all surfactant components are added, and the stirring speed is increased to 380 rpm for 25 minutes of thorough homogenization. Finally, corrosion inhibitors and defoamers are added, the stirring speed is reduced to 220 rpm, and stirring is continued for another 10 minutes, ultimately obtaining a degreasing agent product with a pH of approximately 1.7. Example 8

[0041] The specific composition by weight is as follows: 16 parts of acid-base regulator, composed of 12 parts of aminosulfonic acid and 4 parts of citric acid in a 3:1 mass ratio; 11 parts of composite surfactant, of which nonionic surfactant accounts for a very high proportion, with a nonionic:anionic ratio of 5:1, i.e., 9.17 parts of nonionic surfactant (6.5 parts of isomeric tridecyl alcohol polyoxyethylene polyoxypropylene ether and 2.67 parts of alkyl glycoside), and only 1.83 parts of anionic surfactant sodium dodecylbenzene sulfonate; 4.5 parts of chelating agent, each taking 2.25 parts of sodium gluconate and HEDP in a 1:1 mass ratio; 2 parts of corrosion inhibitor, compounded with imidazoline corrosion inhibitor and lignosulfonate in a 3:1 mass ratio, namely 1.5 parts and 0.5 parts respectively; 1.1 parts of defoamer, polyether-modified siloxane defoamer; 3.8 parts of detergent builder, 2.5 parts of urea and 1.3 parts of sodium polyacrylate; and 58.5 parts of deionized water.

[0042] The preparation process is as follows: At room temperature, deionized water is added to the reactor and stirred at 280 rpm for 7 minutes. Then, sulfamic acid and citric acid are added, and the system temperature is controlled to not exceed 40°C, stirring until clear. Next, sodium gluconate, HEDP, urea, and sodium polyacrylate are added, maintaining a stirring speed of 280 rpm for 14 minutes. Then, a surfactant mixture is added while stirring. Immediately after addition, the stirring speed is significantly increased to 400 rpm and maintained at this high speed for 25 minutes. This is a crucial step to ensure complete dissolution of the high-content nonionic surfactant and system homogeneity. Finally, corrosion inhibitors and defoamers are added, the stirring speed is reduced back to 280 rpm, and stirring continues for 14 minutes. The resulting product has a pH of approximately 2.4. This product is particularly suitable for high-pressure spraying processes with extremely stringent foam requirements. Example 9

[0043] The specific composition, by weight, is as follows: 14 parts acid-base regulator, comprising 9.33 parts aminosulfonic acid and 4.67 parts citric acid, in a mass ratio of 2:1; 13 parts total composite surfactant, comprising 5.5 parts isomeric tridecyl alcohol polyoxyethylene polyoxypropylene ether and 3.5 parts alkyl glycoside, totaling 9 parts, in a mass ratio of 2.25:1 to anionic surfactant (4 parts sodium dodecylbenzenesulfonate); and 5.5 parts chelating agent, composed of 3.67 parts glucose... Sodium gluconate is compounded with 1.83 parts of HEDP at a mass ratio of 2:1; the corrosion inhibitor is 1.5 parts, and is compounded with imidazoline corrosion inhibitor and lignosulfonate at a mass ratio of 1:1 (0.75 parts each); the defoamer is 0.9 parts of polyether modified siloxane defoamer; the detergent is used in an amount of 4 parts as specified in the upper limit of the claims, and urea and sodium polyacrylate are compounded at a mass ratio of 3:1, i.e., 3 parts of urea and 1 part of sodium polyacrylate, to enhance penetration and dispersion; deionized water is 60.1 parts.

[0044] The preparation process is as follows: At room temperature, deionized water is first added to the reactor and stirred at 200 rpm for 10 minutes. Then, sulfamic acid and citric acid are added while stirring, ensuring the temperature rise during dissolution does not exceed 40°C. After complete dissolution, sodium gluconate, HEDP, urea, and sodium polyacrylate are added, and stirred at 200 rpm for 15 minutes. Next, all surfactants are added, and the stirring speed is increased to 300 rpm for 20 minutes. Finally, corrosion inhibitors and defoamers are added, and the stirring speed is maintained at 200 rpm for another 15 minutes, ultimately yielding a degreasing agent product with a pH of approximately 2.0.

[0045] Comparative Example 1 This comparative example is a metal degreasing agent with strong acid and phosphorus-containing additives as its core components. Its specific composition, by weight, is as follows: 15 parts hydrochloric acid (approximately 10% by mass) and 5 parts phosphoric acid are used as the main acid-base regulator and rust-removing agent; 8 parts of a composite surfactant are used, consisting of 5 parts fatty alcohol polyoxyethylene ether (AEO-9) and 3 parts sodium dodecylbenzenesulfonate; 8 parts of sodium tripolyphosphate are used as a chelating agent and detergent builder; the corrosion inhibitor is a compound of 1.5 parts hexamethylenetetramine (urotropine) and 0.5 parts sodium chromate; 0.5 parts of an organosilicon defoamer are used; the remainder is deionized water, brought to a total of 100 parts.

[0046] The preparation method is as follows: Deionized water is added to the reaction vessel, and hydrochloric acid and phosphoric acid are slowly added under strong stirring and external cooling conditions. Then, sodium tripolyphosphate, surfactant, corrosion inhibitor and defoamer are added in sequence and stirred until uniform. The pH value of the obtained product is lower than 1.0.

[0047] Comparative Example 2 This comparative example is a weakly acidic degreasing agent. Its specific composition by weight is as follows: Acid-base regulator is a compound of 8 parts citric acid and 3 parts tartaric acid; the total amount of composite surfactant is 10 parts, entirely composed of nonionic surfactant alkylphenol polyoxyethylene ether (OP-10) and fatty acid methyl ester ethoxylate (FMEE) in a 1:1 ratio, with no anionic surfactant added; chelating agent is 4 parts sodium gluconate; corrosion inhibitor is only 1.5 parts benzotriazole (BTA), mainly targeting copper and copper alloys; defoamer is 1 part mineral oil defoamer; detergent builder is 2 parts sodium citrate; deionized water is added to bring the total to 100 parts.

[0048] The preparation method is as follows: Deionized water is added to a reaction vessel, and citric acid, tartaric acid, sodium gluconate and sodium citrate are added under stirring. After dissolution, surfactant is added, and finally BTA and defoamer are added. The mixture is stirred evenly, and the pH value of the resulting product is about 3.5.

[0049] To verify the technical effectiveness of the liquid high-efficiency and environmentally friendly metal degreasing agent described in this invention, the products obtained in Examples 1-9 and Comparative Examples 1-2 were evaluated for performance according to the following unified test methods and conditions.

[0050] Test samples: Examples 1-9, Comparative Examples 1-2.

[0051] Test substrates: standard cold-rolled steel sheet (SPCC, 50mm×100mm×1mm), aluminum alloy sheet (6061, 50mm×100mm×1mm), galvanized steel sheet (GI, 50mm×100mm×0.8mm).

[0052] Working solution preparation: Prepare each sample into a 5% (v / v) aqueous solution. The test temperature is uniformly set to room temperature (25±20℃), and the test time is uniformly set to 5 minutes (10 minutes for rust removal rate test).

[0053] Key performance testing methods: Degreasing rate: Measured by weight. A standard steel sheet of known weight was uniformly coated with commercially available rust-preventive oil, weighed again, immersed in the working solution and mechanically agitated for 5 minutes, then rinsed, dried, and weighed. Degreasing rate = (weight of removed oil / initial weight of oil) × 100%. Each sample was measured three times, and the average value was taken.

[0054] Rust removal rate: The rust area comparison method was used. A standard rusted steel plate with uniform surface rust was selected, immersed in the working solution for 10 minutes, then removed, rinsed, and dried. The change in rust area before and after treatment was calculated using image analysis software. Rust removal rate = (rust area before treatment - rust area after treatment) / rust area before treatment × 100%.

[0055] Corrosion rate: The weight loss method was used. Polished, precisely weighed standard steel, aluminum, and galvanized sheets were completely immersed in the working solution for 2 hours. After removal, they were cleaned according to national standard (GB / T 10124-1988) to remove corrosion products, dried, and weighed. The weight loss per unit area per unit time was calculated, in g / (m²). 2 ·h).

[0056] Foaming performance: Modified using the Roche foaming method. Measure 500 mL of working solution into a 1000 mL graduated cylinder and stir at a constant stirring speed for 1 min. Immediately after stirring, record the foam height (initial foam height). After standing for 5 min, record the foam height again (5 min foam height). Unit: mm.

[0057] Working fluid lifespan (stability): Prepare 5L of 5% working fluid for continuous use. After treating each batch of oily and rusty workpieces, add a small amount of the original fluid to maintain the fluid level. The endpoint is defined as the solution becoming significantly turbid, precipitating, or the degreasing rate decreasing to below 80% of the initial value. Record the total cumulative treated working area (m²). 2 / L).

[0058] pH value: The pH value of the 5% working solution is measured directly using a precision pH meter.

[0059] The performance test results are shown in Table 1. Table 1 Key Performance Test Data .

[0060] In Table 1, "complete corrosion" indicates that the surface of the test piece has undergone severe and comprehensive corrosion, making it impossible to accurately measure the rate; "coating peeling" indicates that the zinc plating layer has been completely destroyed.

[0061] The working fluid life is a relative value obtained from simulated accelerated testing; a higher value indicates better stability and a longer service life.

[0062] As shown in the table above, Examples 1-9 of this invention exhibit excellent synergistic effects of high degreasing rate (≥98.0%) and high rust removal rate (≥96.0%), while showing extremely low corrosion rates on various metal substrates, fully demonstrating a balance between high efficiency and low corrosion. All examples show low foaming and rapid defoaming, long working fluid life, and stable pH values ​​within the optimized range of 1.5-3.0, fully achieving the invention's objectives. Comparative Example 1: Although the rust removal rate is extremely high, the degreasing rate is low, and the corrosiveness to metals (especially aluminum and galvanized sheets) is extremely severe. It produces a lot of foam that is difficult to eliminate, the working fluid is prone to failure, and its environmental performance is poor (containing phosphorus and chromium). Comparative Example 2: Environmental performance is somewhat improved, but the rust removal ability is severely insufficient, the corrosion rate on aluminum alloys is relatively high, and the foaming performance is poor, reflecting the compromises and imbalances in performance of ordinary environmentally friendly products on the market.

[0063] In summary, the performance verification data fully demonstrate that the liquid high-efficiency and environmentally friendly metal degreasing agent and its preparation method provided by the present invention comprehensively solve a series of problems pointed out in the background technology, such as the imbalance between degreasing and rust removal efficiency, substrate corrosion, excessive foaming, short lifespan, and lack of environmental protection, and are significantly superior to the existing technology.

Claims

1. A liquid, highly efficient, and environmentally friendly metal degreasing agent, characterized in that, It is composed of the following components in parts by weight: 10-20 parts acid-base regulator; 8-15 parts compound surfactant; 3-6 parts chelating agent; 1-3 parts corrosion inhibitor; 0.5-1.5 parts defoamer; 2-4 parts detergent builder; and 50-65 parts deionized water.

2. The liquid high-efficiency and environmentally friendly metal degreasing agent according to claim 1, characterized in that: The acid-base regulator is a compound of aminosulfonic acid and organic acid.

3. The liquid high-efficiency and environmentally friendly metal degreasing agent according to claim 2, characterized in that: The organic acid is citric acid; the mass ratio of aminosulfonic acid to citric acid is 2~4:

1.

4. The liquid high-efficiency and environmentally friendly metal degreasing agent according to claim 1, characterized in that: The composite surfactant includes nonionic surfactants and anionic surfactants.

5. The liquid high-efficiency and environmentally friendly metal degreasing agent according to claim 4, characterized in that: The mass ratio of the nonionic surfactant to the anionic surfactant is 2~5:

1.

6. The liquid high-efficiency and environmentally friendly metal degreasing agent according to claim 5, characterized in that: The nonionic surfactant is a compound of isotridecyl alcohol polyoxyethylene polyoxypropylene ether and alkyl glycoside, and the anionic surfactant is sodium dodecylbenzenesulfonate.

7. The liquid high-efficiency and environmentally friendly metal degreasing agent according to claim 1, characterized in that: The chelating agent is a compound of sodium gluconate and hydroxyethylidene diphosphonic acid, with a mass ratio of 1 to 2:1; the corrosion inhibitor is a compound of imidazoline corrosion inhibitor and lignin sulfonate, with a mass ratio of 1 to 3:

1.

8. The liquid high-efficiency and environmentally friendly metal degreasing agent according to claim 1, characterized in that: The defoamer is a polyether-modified siloxane defoamer; the detergent builder is a compound of urea and a phosphate-free detergent builder.

9. The liquid high-efficiency and environmentally friendly metal degreasing agent according to claim 1, characterized in that: Its pH value is 1.5~3.

0.

10. A method for preparing a liquid, highly efficient, and environmentally friendly metal degreasing agent as described in any one of claims 1 to 9, characterized in that, Includes the following steps: (1) Weigh each raw material according to the proportions; (2) Add deionized water to the reactor and stir for 5-10 minutes; (3) Add acid-base regulator and stir until completely dissolved; (4) Add chelating agent and washing aid, and stir for 10-15 minutes; (5) Add the composite surfactant and stir for 20-25 minutes until homogeneous; (6) Finally, add corrosion inhibitor and defoamer, stir for 10 min to 15 min to obtain the finished product.