Metal cleaning agent and method for preparing the same

Abstract

The application belongs to the technical field of industrial metal cleaning, and discloses a metal cleaning agent and a preparation method thereof.The metal cleaning agent comprises the following components in percentage by weight: non-ion complex surfactant 15-25%, anion surfactant 3-8%, multi-metal complex corrosion inhibitor 1-5%, chelating agent 3-8%, penetrating agent 1-4%, and water 50-77%; the non-ion complex surfactant comprises isomeric decanol polyoxyethylene ether, isomeric tridecanol polyoxyethylene ether and fatty acid methyl ester ethoxylate; the multi-metal complex corrosion inhibitor comprises benzotriazole, silicate, gluconate and phytic acid.The metal cleaning agent provided by the application can realize low-temperature and high-efficiency decontamination for various metals, has no corrosion damage, is stable with low foam, and has no residue on the surface of the metal after cleaning.

Description

Technical Field

[0001] This invention belongs to the field of industrial metal cleaning technology, specifically relating to a metal cleaning agent and its preparation method. Background Technology

[0002] During the cutting, stamping, rolling, and welding processes, metal workpieces inevitably accumulate oil stains such as cutting fluid, lubricating oil, rust-preventive oil, and mold release agents, as well as impurities such as metal chips, oxide films, and dust. These deposits directly affect the processing quality of subsequent processes such as coating, electroplating, welding, and passivation, and may even reduce the service life of metal workpieces and the product qualification rate. Therefore, metal surface cleaning is an indispensable key process in industrial production.

[0003] At present, industrial metal cleaning mainly uses two types of cleaning agents: solvent-based cleaning agents and traditional water-based alkaline cleaning agents. With the improvement of environmental protection requirements and the increase in demand for multi-metal co-line cleaning, the existing technology has many insurmountable defects, as follows: (1) The environmental protection and safety hazards of solvent-based cleaning agents are prominent: Traditional solvent-based cleaning agents mostly use volatile organic solvents such as trichloroethylene, dichloromethane, gasoline, and kerosene. Although they have strong cleaning ability, they are flammable and explosive. During the volatilization process, they release a large amount of volatile organic compounds (VOCs), which seriously pollute the atmospheric environment and have strong irritant effects on the respiratory tract and skin of operators. Long-term exposure may pose a carcinogenic risk. At the same time, this type of cleaning agent is difficult to biodegrade, and the waste liquid treatment is difficult and costly. It no longer meets the national policy requirements for green and environmentally friendly production and is gradually being restricted. (2) Low efficiency of traditional water-based cleaning agents at low temperatures: Conventional water-based metal cleaning agents are mostly strongly alkaline formulas, which rely on high temperature (50-80℃) heating to improve the cleaning ability. Under low temperature (20-40℃) conditions, the surfactant activity is low, the wetting, penetration and emulsification ability is greatly reduced, and it is impossible to effectively remove stubborn oil stains and heavy impurities. It is necessary to extend the cleaning time or increase the cleaning frequency, which leads to a significant increase in energy consumption and a decrease in production efficiency, and cannot meet the needs of continuous and efficient cleaning of automated production lines. (3) Poor compatibility with multiple metals and easy to cause metal corrosion: Most cleaning agents are designed to be compatible with a single metal. They have a certain cleaning effect on ferrous metals such as carbon steel and stainless steel, but they are extremely corrosive to non-ferrous metals such as aluminum alloys, copper alloys and zinc alloys. They are prone to problems such as whitening, oxidation and pitting of aluminum alloys, discoloration and rusting of copper alloys, and corrosion and peeling of zinc alloys. Some cleaning agents with added single corrosion inhibitors can only alleviate the corrosion of a single metal and cannot achieve comprehensive protection when cleaning multiple metal materials simultaneously, which limits the promotion of multi-metal co-line cleaning process. (4) Environmental performance is not up to standard and the residue problem is serious: Traditional water-based cleaning agents generally contain phosphates, silicates, sodium nitrites, borates and other components. Phosphates will cause eutrophication of water bodies, sodium nitrites are carcinogenic, and borates are difficult to biodegrade and do not meet environmental emission standards. At the same time, some cleaning agents leave a large amount of residue on the metal surface after cleaning, requiring multiple rinsing, which consumes a lot of water. Moreover, the residue will affect the bonding force of subsequent processes, resulting in problems such as coating peeling and uneven electroplating. (5) Large amount of foam and poor compatibility: Conventional cleaning agents are prone to generating a large amount of foam during spraying and ultrasonic cleaning. Foam overflow will cause cleaning fluid loss, equipment failure and affect the continuity of cleaning operations. Although adding defoamers can alleviate this, defoamers will reduce the stability of the cleaning fluid and the defoaming effect is poor at low temperatures, making it unsuitable for various cleaning processes such as high-pressure spraying and ultrasonic cleaning.

[0004] In summary, existing metal cleaning agents cannot simultaneously meet the comprehensive performance requirements of low-temperature high efficiency, multi-metal compatibility, environmental friendliness, low foaming, and easy rinsing, making them unsuitable for the current development trend of green, high-efficiency, and multi-material co-line cleaning in industrial production. Therefore, developing a new type of cleaning agent that can quickly remove contaminants at low temperatures, is non-corrosive to multiple metals, leaves no residue, and is compatible with various cleaning processes has become an urgent technical challenge to be solved in the field of industrial cleaning. Summary of the Invention

[0005] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a metal cleaning agent and its preparation method. The cleaning agent provided by this invention can quickly and efficiently remove contaminants at low temperatures of 20-40℃, is non-corrosive to various metals such as carbon steel, stainless steel, aluminum alloy, copper alloy, and zinc alloy, and is free of phosphorus, nitrogen, nitrite, and VOCs. It is also easily biodegradable, low-foaming, and easy to rinse.

[0006] This invention provides a metal cleaning agent.

[0007] Specifically, a metal cleaning agent comprises the following components by weight percentage: Nonionic composite surfactants: 15%-25% Anionic surfactants: 3%-8% Multi-metal composite corrosion inhibitor: 1%-5% Chelating agents: 3%-8% Penetrant: 1%-4% Water: 50%-77%; The nonionic composite surfactant includes isomeric decayl alcohol polyoxyethylene ether, isomeric tridecyl alcohol polyoxyethylene ether, and fatty acid methyl ester ethoxylate; the multimetal composite corrosion inhibitor includes benzotriazole, silicate, gluconate, and phytic acid.

[0008] In some embodiments of the present invention, the metal cleaning agent comprises, by weight percentage, the following components: Nonionic composite surfactants: 15%-23% Anionic surfactants: 3%-8% Multi-metal composite corrosion inhibitor: 2%-5% Chelating agents: 4%-7% Penetrant: 1%-3% Water: 54%-75%.

[0009] In some embodiments of the present invention, in the nonionic composite surfactant, the mass ratio of the isomeric decayl alcohol polyoxyethylene ether to the isomeric tridecyl alcohol polyoxyethylene ether and the fatty acid methyl ester ethoxylate is (3-6):(1.5-3):1; preferably, the mass ratio of the isomeric decayl alcohol polyoxyethylene ether to the isomeric tridecyl alcohol polyoxyethylene ether and the fatty acid methyl ester ethoxylate is (3-5):(1.5-2.5):1. The nonionic surfactant composite system at this ratio exhibits excellent low-temperature wettability, penetration, and emulsifying and detergency capabilities. Its cloud point is suitable for the low-temperature range of 20-40℃, and it exhibits high surface activity at low temperatures. It can quickly penetrate the interface between oil and metal surfaces, emulsifying and dispersing stubborn oil stains. Furthermore, it does not contain recalcitrant components such as alkylphenol polyoxyethylene ether (APEO), is readily biodegradable, and its low-foaming properties make it suitable for spray and ultrasonic cleaning.

[0010] In some embodiments of the present invention, in the multi-metal composite corrosion inhibitor, the mass ratio of benzotriazole to the silicate, the gluconate, and the phytic acid is (1.2-3.0):(0.8-1.5):(0.8-1.5):(2.0-4.0). Preferably, the mass ratio of benzotriazole to the silicate, the gluconate, and the phytic acid is (1.5-2.5):(0.8-1.2):(0.8-1.2):(2.5-3.5). Benzotriazole has excellent corrosion inhibition effects on copper alloys and zinc alloys, and can form a dense protective film on the metal surface; silicates (such as sodium salts) and gluconates (such as sodium salts) provide passivation protection for carbon steel and stainless steel; phytic acid has a synergistic corrosion inhibition effect on multiple metals, and can also chelate metal ions to prevent secondary deposition, achieving comprehensive non-corrosion protection for multi-metal materials. By controlling the ratio of benzotriazole to silicate, gluconate, and phytic acid, the corrosion inhibition and passivation effects can be further improved.

[0011] In some embodiments of the present invention, the anionic surfactant includes one or a mixture of two of fatty acid methyl ester sulfonates (such as sodium salts) and lauroyl sarcosinates (such as sodium salts). This type of surfactant is environmentally friendly and works synergistically with nonionic surfactants to improve low-temperature detergency, while reducing the surface tension of the cleaning solution, enhancing oil dispersion, and exhibiting strong resistance to hard water. It does not precipitate with calcium and magnesium ions in water, ensuring the stability of the cleaning solution.

[0012] In some embodiments of the present invention, the chelating agent includes at least one of ethylenediamine di-o-phenylacetate (such as sodium salt) and glutamate diacetate (such as tetrasodium glutamate diacetate). This type of chelating agent is a green and biodegradable chelating agent, free of phosphorus and nitrogen, which can effectively chelate metal ions such as calcium, magnesium, and iron in water, preventing scale and impurities from depositing on metal surfaces, improving the detergency and rinsing performance of cleaning solutions, avoiding cleaning residues, and fully complying with environmental emission standards.

[0013] In some embodiments of the present invention, the penetrant includes at least one of polyether-modified siloxane and isooctanol succinate sulfonate. The penetrant exhibits excellent low-temperature penetration performance, which can rapidly reduce the amount of foam in the cleaning agent system provided by the present invention, preventing foam overflow during spraying and ultrasonic cleaning, while simultaneously enhancing the penetrating cleaning ability of the cleaning liquid to small gaps and blind holes, ensuring cleaning uniformity.

[0014] In some embodiments of the present invention, the water is deionized water, preferably deionized water with a resistivity ≥18MΩ·cm, to avoid impurities in tap water affecting the stability and cleaning effect of the cleaning solution and to prevent secondary pollution of the metal surface.

[0015] In some embodiments of the present invention, the metal cleaning agent further includes a pH adjuster; the pH adjuster accounts for 1%-2% by weight.

[0016] In some embodiments of the present invention, the pH adjuster is selected from citric acid and / or triethanolamine.

[0017] In some embodiments of the present invention, the metal cleaning agent has a pH value of 7.5-8.5, is weakly alkaline, avoids the corrosion of non-ferrous metals by strong alkalinity, and ensures low-temperature cleaning effect, making it suitable for cleaning multiple metal materials.

[0018] This invention provides a method for preparing a metal cleaning agent.

[0019] Specifically, a method for preparing a metal cleaning agent includes the following steps: A nonionic composite surfactant and anionic surfactant are mixed to obtain a mixed surfactant solution; a multi-metal composite corrosion inhibitor and a chelating agent are added to the mixed surfactant solution and mixed to obtain a mixed base solution; then, some water is added to the mixed base solution for dilution; finally, a pH adjuster, a low-foaming penetrant and the remaining water are added to obtain a metal cleaning agent.

[0020] In some embodiments of the present invention, the mass of the portion of water accounts for 80%-95% of the total water volume, and the mass of the remaining water accounts for 5%-20% of the total water volume.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The metal cleaning agent provided by the present invention, through the synergistic compounding of nonionic composite surfactant and anionic surfactant, can quickly activate surface activity under low temperature conditions of 20-40℃. It has excellent wetting, penetration and emulsification capabilities, and can quickly remove heavy oil stains, oxide scale and impurities from metal surfaces. The cleaning time is shortened by more than 40% compared with traditional high temperature cleaning agents. No heating is required, saving a lot of heat energy, reducing production energy consumption, and adapting to automated continuous cleaning production lines to improve production efficiency. The compounded metal corrosion inhibitor can form a uniform and dense composite protective film on the metal surface according to the different corrosion characteristics of ferrous and non-ferrous metals. It is non-corrosive, non-discoloring and non-pitting to various metals such as carbon steel, stainless steel, aluminum alloy, copper alloy and zinc alloy, realizing multi-metal material co-line cleaning, broadening the application range of the cleaning agent and solving the limitation of traditional cleaning agents that are only suitable for a single metal. By adding a low-foaming penetrant, the cleaning agent produces very little foam during high-pressure spraying and ultrasonic cleaning, eliminating foam overflow and preventing cleaning fluid loss and equipment malfunction. The cleaning fluid exhibits excellent stability, remaining unchanged without stratification, sedimentation, or deterioration after six months of storage at room temperature. It also demonstrates strong resistance to hard water and is suitable for various water quality conditions. Furthermore, the metal cleaning agent provided by this invention is free of phosphorus, nitrogen, nitrite, APEO, and volatile organic solvents. All components are readily biodegradable, preventing eutrophication and air pollution. Wastewater treatment is simple and compliant with national environmental protection policies. No residue remains on the metal surface after cleaning, eliminating the need for multiple rinsing cycles and reducing water consumption by over 30%, thus preventing residual substances from affecting the quality of subsequent processes. The preparation process of this metal cleaning agent is simple and low-cost: the preparation process does not require high temperature and pressure, can be completed at room temperature and pressure, is easy to operate, has low energy consumption, and uses commercially available conventional environmentally friendly raw materials, resulting in low procurement costs. It is suitable for large-scale industrial production, combining economic and environmental benefits.

[0022] (2) The metal cleaning agent provided by this invention can achieve low-temperature and efficient cleaning of various metals without corrosion damage, and is low-foaming and stable, leaving no residue on the metal surface after cleaning. It is especially suitable for cleaning oil stains, oxide scale, dust and processing residues on the surface of workpieces made of various metal materials such as carbon steel, stainless steel, aluminum alloy, copper alloy and zinc alloy, and can be widely used in precision cleaning processes in industries such as machinery manufacturing, aerospace, automotive parts, and electronic hardware. Detailed Implementation

[0023] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0024] The surfactants and penetrants used in this invention are all commercially available standardized industrial raw materials. The key components are consistently sourced from the following commercially available manufacturers: isomeric decayl alcohol polyoxyethylene ether is Zhejiang Jingguang Industrial Co., Ltd. E-1007; isomeric tridecyl alcohol polyoxyethylene ether is Zhejiang Jingguang Industrial Co., Ltd. E-1306; fatty acid methyl ester ethoxylate is Zhongqing Daily Chemical Co., Ltd. FMEE-24-10; low-foaming penetrant polyether modified siloxane is Evonik TEGOPREN 6924; and the alkylphenol polyoxyethylene ether used in the comparative examples is NP-10 (nonylphenol polyoxyethylene ether, from Zhejiang Huangma Technology). Unless otherwise specified, other raw materials, reagents, or apparatus can be obtained from conventional commercial sources or through existing known methods. Those skilled in the art can reproduce all embodiments and comparative products of this invention without difference based on the formulation and process parameters of this invention.

[0025] Example 1 This embodiment provides a low-temperature, high-efficiency, environmentally friendly, multi-metal compatible metal cleaning agent, which is composed of the following components by weight percentage: Nonionic composite surfactant (isomeric decayl alcohol polyoxyethylene ether: isomeric tridecayl alcohol polyoxyethylene ether: fatty acid methyl ester ethoxylate = 3:1.5:1): 18% Sodium methyl ester sulfonate of fatty acids: 5% Multimetallic composite corrosion inhibitor (benzotriazole: sodium silicate: sodium gluconate: phytic acid = 1.5:0.8:0.8:2.5): 3% Sodium ethylenediamine di-o-phenylacetate: 5% Polyether-modified siloxane (low-foaming penetrant): 2% Citric acid: 0.5% Triethanolamine: 1% Deionized water: Balance.

[0026] The preparation method of this metal cleaning agent is as follows: Weigh out the nonionic composite surfactant and sodium fatty acid methyl ester sulfonate, place them in a 32℃ stirring container, and stir at 350 r / min for 18 min until well mixed; then add the multi-metal composite corrosion inhibitor and sodium ethylenediamine di-o-phenylacetate, and stir at 32℃ and 450 r / min for 22 min until completely dissolved; add 90% of the total amount of deionized water and stir to dilute; add citric acid and triethanolamine in batches, stir at 350 r / min for 12 min, monitor online and adjust the pH to 8.0; then add polyether modified siloxane, stir evenly, add the remaining 10% of deionized water, and stir at 250 r / min at room temperature for 28 min to obtain the finished cleaning agent.

[0027] Example 2 This embodiment provides a low-temperature, high-efficiency, environmentally friendly, multi-metal compatible metal cleaning agent, which is composed of the following components by weight percentage: Nonionic composite surfactant (isodecyl alcohol polyoxyethylene ether: isodecyl alcohol polyoxyethylene ether: fatty acid methyl ester ethoxylate = 4:2:1): 22% Sodium lauroyl sarcosinate: 6% Multi-metal composite corrosion inhibitor (benzotriazole: sodium silicate: sodium gluconate: phytic acid = 2:1:1:3): 4% Tetrasodium glutamate diacetate: 6% Sodium isooctanol succinate sulfonate: 2.5% Triethanolamine: 1.8% Deionized water: Balance.

[0028] The preparation method of this metal cleaning agent is as follows: Weigh out the nonionic composite surfactant and sodium lauroyl sarcosinate, place them in a 34℃ stirring container, and stir at 380 rpm for 16 min to mix thoroughly. Then add the multi-metal composite corrosion inhibitor and tetrasodium glutamate diacetate, and stir at 34℃ and 480 rpm for 20 min to completely dissolve and obtain a mixed base solution. Add 90% of the total amount of deionized water to the mixed base solution and stir to dilute. Add triethanolamine in batches, stir at 380 rpm for 14 min, monitor online and adjust the pH to 8.2. Then add sodium isooctanol succinate sulfonate and stir evenly. Finally, add the remaining 10% of deionized water, stir at 280 rpm at room temperature for 26 min, and fine-tune the system concentration to obtain the finished cleaning agent.

[0029] Example 3 This embodiment provides a low-temperature, high-efficiency, environmentally friendly, multi-metal compatible metal cleaning agent, which is composed of the following components by weight percentage: Nonionic composite surfactant (isomeric decayl alcohol polyoxyethylene ether: isomeric tridecayl alcohol polyoxyethylene ether: fatty acid methyl ester ethoxylate = 5:2.5:1): 16% Anionic surfactant (sodium fatty acid methyl ester sulfonate: sodium lauroyl sarcosinate = 1:1): 4% Multi-metal composite corrosion inhibitor (benzotriazole: sodium silicate: sodium gluconate: phytic acid = 2.5:1.2:1.2:3.5): 2.5% Chelating agent (sodium ethylenediamine di-o-phenylacetate: tetrasodium glutamate diacetate = 1:1): 4.5% Polyether-modified siloxane (low-foaming penetrant): 1.5% Citric acid: 1.2% Deionized water: Balance.

[0030] The preparation method of this metal cleaning agent is as follows: Weigh out the nonionic composite surfactant and the compounded anionic surfactant, place them in a 30℃ stirring container, and stir at 320 rpm for 20 min to mix thoroughly. Then add the multi-metal composite corrosion inhibitor and the mixed chelating agent, and stir at 30℃ and 420 rpm for 25 min until completely dissolved to obtain a mixed base solution. Add 90% of the total amount of deionized water to the mixed base solution and stir to dilute. Add citric acid in batches, stir at 320 rpm for 15 min, monitor online and adjust the pH to 7.8. Then add polyether-modified siloxane and stir evenly. Finally, add the remaining 10% of deionized water, stir at 220 rpm at room temperature for 30 min, and fine-tune the system concentration to obtain the finished cleaning agent. Comparative Example 1 Uses commercially available water-based metal cleaning agents containing phosphates and sodium nitrite, pH=11, strongly alkaline, requires heating to 60℃ for use, and is only suitable for cleaning carbon steel.

[0031] Comparative Example 2 Commercially available solvent-based metal cleaning agents were selected. The main component is trichloroethylene, which is highly volatile, contains VOCs, and has no corrosion inhibitors.

[0032] Comparative Example 3 The difference between this comparative example and Example 1 is that it does not contain a multi-metal composite corrosion inhibitor and uses deionized water instead. The remaining components and preparation methods are the same as in Example 1.

[0033] Comparative Example 4 The difference between this comparative example and Example 1 is that the nonionic composite surfactant is replaced with conventional alkylphenol polyoxyethylene ether, while the remaining components and preparation methods are the same as in Example 1.

[0034] Comparative Example 5 The difference between this comparative example and Example 1 is that the composition of the nonionic composite surfactant is: isomeric decayl alcohol polyoxyethylene ether: isomeric tridecyl alcohol polyoxyethylene ether: fatty acid methyl ester ethoxylate = 1:1:1, and the remaining components and preparation methods are the same as in Example 1.

[0035] Comparative Example 6 The difference between this comparative example and Example 1 is that the composition of the nonionic composite surfactant is: isomeric deca-ol polyoxyethylene ether: fatty acid methyl ester ethoxylate = 1:1, and the remaining components and preparation methods are the same as in Example 1.

[0036] Comparative Example 7 The difference between this comparative example and Example 1 is that the multi-metal composite corrosion inhibitor (benzotriazole: sodium silicate: sodium gluconate = 1:1:1) is used, while the other components and preparation methods are the same as in Example 1.

[0037] Comparative Example 8 The difference between this comparative example and Example 1 is that the multi-metal composite corrosion inhibitor (sodium silicate: sodium gluconate: phytic acid = 2:2:3) is used, while the other components and preparation methods are the same as in Example 1.

[0038] Comparative Example 9 The difference between this comparative example and Example 1 is that the metal cleaning agent, by weight percentage, consists of the following components: Nonionic composite surfactant (isomeric decayl alcohol polyoxyethylene ether: isomeric tridecayl alcohol polyoxyethylene ether: fatty acid methyl ester ethoxylate = 3:1.5:1): 12% Sodium methyl ester sulfonate of fatty acids: 10% Multimetallic composite corrosion inhibitor (benzotriazole: sodium silicate: sodium gluconate: phytic acid = 1.5:0.8:0.8:2.5): 1% Sodium ethylenediamine di-o-phenylacetate: 5% Polyether-modified siloxane (low-foaming penetrant): 5% Citric acid: 0.5% Triethanolamine: 1% Deionized water: Balance.

[0039] The preparation method of this metal cleaning agent is the same as in Example 1.

[0040] Product effectiveness test The metal cleaning agents prepared in the above embodiments and comparative examples were tested for effectiveness. The test items and specific test methods are as follows: (1) Stability test during room temperature storage Accurately measure 100 mL of each metal cleaning agent to be tested and place it in a 100 mL stoppered graduated cylinder. Store the sample in a constant temperature and light-protected environment at 25℃±2℃ for 30 days. Observe the appearance of the sample on the 7th, 14th, 21st and 30th days and record whether the sample shows phenomena such as layering, turbidity, precipitation, exudation, discoloration, or odor. The storage stability is determined by the final state after 30 days: no layering, no turbidity, and no precipitation are considered stable; slight turbidity and a small amount of flocculent matter are considered relatively stable; severe layering and precipitation are considered unstable.

[0041] (2) Corrosion rating test of carbon steel Referring to the corrosion test method in QB / T 2117-1995 "General Water-Based Metal Cleaning Agents", the full immersion corrosion method was adopted: the 45# carbon steel standard test piece was polished stepwise with 400# and 800# sandpaper, degreased with anhydrous ethanol, dried with cold air, and weighed; the test piece was completely immersed in a 5% concentration of the metal cleaning agent to be tested, and continuously immersed at a constant temperature of 30℃ for 24 hours; the test piece was taken out, rinsed with deionized water and anhydrous ethanol, dehydrated, dried with cold air, and the corrosion state of the test piece surface was observed by visual inspection combined with stereomicroscope, and the corrosion level was determined with reference to Table 1.

[0042] Table 1 Corrosion Levels

[0043] (3) Corrosion test of aluminum alloy and copper alloy The constant-temperature immersion method was adopted: 6061 aluminum alloy and H62 copper alloy standard test pieces were sanded, degreased with anhydrous ethanol, dried, and weighed. They were then completely immersed in a 5% concentration of the metal cleaning agent to be tested and immersed at a constant temperature of 30℃ for 12 hours. The test pieces were then removed, rinsed with deionized water, and dried with cold air. The surface corrosion was then observed visually and under a microscope: Aluminum alloy: focus on observing whether whitening, oxidation spots, pitting, powdering, peeling, etc., appeared on the surface; Copper alloy: focus on observing whether oxidation discoloration, blackening, verdigris, rust spots, loss of metallic luster, etc., appeared on the surface.

[0044] (4) Foam volume test The graduated cylinder oscillation method was used: 50 mL of the diluted working solution (concentration 5%) of the metal cleaning agent to be tested was measured at room temperature and placed in a 100 mL graduated cylinder with a stopper. The cylinder was oscillated vigorously up and down 30 times (oscillation frequency 1 time / s). After oscillation, the cylinder was allowed to stand for 1 minute immediately, and the height of the foam layer on the liquid surface was accurately recorded. The foam height was classified into grades: foam height ≤ 5 mm was very little, foam height 5-20 mm was a small amount, foam height ≥ 20 mm was a large amount, and no foam was recorded as none.

[0045] (5) Residual status test Before testing, a unified cleaning process was performed. The cleaning process conditions were as follows: The working solution is prepared by diluting 5 wt% cleaning agent with 95 wt% deionized water with resistivity ≥18 MΩ·cm. Cleaning method: Ultrasonic cleaning, ultrasonic power 300W, ultrasonic frequency 40kHz; Cleaning temperature: constant 30℃; Cleaning time: 5 minutes for ultrasonic cleaning of the workpiece; Cleaning samples: 45# carbon steel, 6061 aluminum alloy, H62 copper alloy standard test pieces (size 50mm×25mm×2mm); Rinsing process: After cleaning, rinse with room temperature deionized water for 2 minutes, and hang to air dry naturally vertically (room temperature 25℃, in a well-ventilated and dark environment).

[0046] Judgment Method: After uniform cleaning, a combination of visual observation, wiping verification, and water film continuity test is used for judgment. Specific steps are as follows: After standard cleaning and rinsing with pure water, each metal sample is air-dried. First, visually observe the surface of the sample for any hazy residual film, white precipitates, or sticky stains. Then, gently wipe the surface of the sample with clean, non-toxic filter paper and observe whether the filter paper is stained with residual stains. Finally, spray deionized water onto the surface of the sample and observe whether the water film is continuous, uniform, without pinholes or breaks. Overall Judgment Results: No Residue: No residual film or precipitate on the surface, no stains on the filter paper, and a continuous and intact water film; Slight Residue: Slightly hazy surface, slightly discontinuous water film, and no obvious stains on the filter paper; Small Residue: Slight white spots are visible on the surface, and the filter paper is stained with a small amount of stains; Large Residue: Obvious residual film and white spots cover the surface, the filter paper is stained with a large amount of stains, and the water film is completely broken.

[0047] (6) The biodegradation rate was tested in accordance with GB / T 15818-2018 standard; (7) The decontamination rate at 30℃ is tested according to the standard QB / T 2117-1995 for general water-based metal detergents.

[0048] The test results are shown in Tables 2 and 3.

[0049] Table 2 Test results of Examples 1-3 and Comparative Examples 1-3

[0050] Table 3 shows the test results of Comparative Examples 4-9.

[0051] Test results show that the metal cleaning agents provided in Examples 1-3 of this invention have a low-temperature decontamination rate of over 98.5%, and are non-corrosive to various metals (carbon steel, aluminum alloy, copper alloy), produce very little foam, have a biodegradation rate of over 90%, are stable, and leave no residue after cleaning. Their effects are far superior to those of the comparative examples, and can better meet the needs of low-temperature environmentally friendly cleaning of multi-metals in industry.

[0052] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are 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. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A metal cleaning agent, characterized in that, By weight percentage, it includes the following components: Nonionic composite surfactants: 15%-25% Anionic surfactants: 3%-8% Multi-metal composite corrosion inhibitor: 1%-5% Chelating agents: 3%-8% Penetrant: 1%-4% Water: 50%-77%; The nonionic composite surfactant includes isomeric decayl alcohol polyoxyethylene ether, isomeric tridecyl alcohol polyoxyethylene ether, and fatty acid methyl ester ethoxylate; the multimetal composite corrosion inhibitor includes benzotriazole, silicate, gluconate, and phytic acid.

2. The metal cleaning agent according to claim 1, characterized in that, By weight percentage, it includes the following components: Nonionic composite surfactants: 15%-23% Anionic surfactants: 3%-8% Multi-metal composite corrosion inhibitor: 2%-5% Chelating agents: 4%-7% Penetrant: 1%-3% Water: 54%-75%.

3. The metal cleaning agent according to claim 1 or 2, characterized in that, In the nonionic composite surfactant, the mass ratio of the isomeric decayl alcohol polyoxyethylene ether to the isomeric tridecyl alcohol polyoxyethylene ether and the fatty acid methyl ester ethoxylate is (3-6):(1.5-3):

1.

4. The metal cleaning agent according to claim 3, characterized in that, The mass ratio of the isomeric decayl alcohol polyoxyethylene ether to the isomeric tridecyl alcohol polyoxyethylene ether and the fatty acid methyl ester ethoxylate is (3-5):(1.5-2.5):

1.

5. The metal cleaning agent according to claim 1 or 2, characterized in that, In the multi-metal composite corrosion inhibitor, the mass ratio of benzotriazole to silicate, gluconate and phytic acid is (1.2-3.0):(0.8-1.5):(0.8-1.5):(2.0-4.0).

6. The metal cleaning agent according to claim 1 or 2, characterized in that, The anionic surfactant includes one or a mixture of two of fatty acid methyl ester sulfonate and lauroyl sarcosine salt.

7. The metal cleaning agent according to claim 1 or 2, characterized in that, The chelating agent includes at least one of ethylenediamine di-o-phenylacetate and glutamic acid diacetate.

8. The metal cleaning agent according to claim 1 or 2, characterized in that, The penetrant includes at least one of polyether-modified siloxane and isooctyl succinate sulfonate.

9. The metal cleaning agent according to claim 1 or 2, characterized in that, The metal cleaning agent also includes a pH adjuster; the pH adjuster accounts for 1%-2% by weight.

10. The method for preparing the metal cleaning agent according to claim 9, characterized in that, Includes the following steps: A nonionic composite surfactant and anionic surfactant are mixed to obtain a mixed surfactant solution; a multi-metal composite corrosion inhibitor and a chelating agent are added to the mixed surfactant solution and mixed to obtain a mixed base solution; a low-foaming penetrant and a pH adjuster are then added to the mixed base solution, and finally water is added to obtain a metal cleaning agent.

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