Surfactant, preparation method and industrial cleaning agent

Abstract

The invention relates to the technical field of industrial cleaning, and discloses a surfactant and a preparation method thereof, and an industrial cleaning agent, the surfactant comprises the following components by weight: 10-60 parts of nonionic polyoxyethylene fatty alcohol ether, 10-60 parts of anionic polyoxyethylene fatty alcohol ether sulfate, 5-40 parts of a modified alkyl polyglycoside solution, 2-14 parts of an auxiliary agent, and 10-40 parts of water; the modified alkyl polyglucoside solution is obtained by carrying out etherification reaction on alkyl polyglucoside and halogenated acetate containing a carboxymethyl functional group under an alkaline condition. According to the invention, the gelation problem during high-concentration compounding can be avoided, and the stability and cleaning performance of the system are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of industrial cleaning technology, and in particular to a surfactant, its preparation method, and an industrial cleaning agent. Background Technology

[0002] Industrial cleaning agents are widely used in metal processing, machinery manufacturing, electronic components, and precision instruments to remove grease, particulate matter, and inorganic dirt from surfaces. With increasingly stringent environmental regulations and rising demands for cleaning efficiency in industrial production, the market is placing greater challenges on the performance of industrial cleaning agents.

[0003] Existing industrial cleaning agents often employ a compound system of nonionic and anionic surfactants. However, in high-hardness water, these systems are easily affected by calcium and magnesium ions, leading to reduced detergency and precipitation. Meanwhile, while conventional alkyl polysaccharides (APGs) are environmentally friendly, their hydrophilicity, alkali resistance, and resistance to redeposition of dirt are weak, limiting their application in cleaning heavy oil stains. Furthermore, traditional processes are prone to "gelation" when preparing high-concentration compound systems, resulting in a sudden increase in system viscosity, difficulty in uniform mixing, and often leading to products with poor low-temperature stability and easy stratification during long-term storage. These shortcomings fail to meet the demands of modern industry for efficient and stable cleaning agents. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a surfactant, its preparation method, and an industrial cleaning agent that can avoid the gelation problem when compounded at high concentrations, and significantly improve the stability and cleaning performance of the system.

[0005] The present invention solves the above-mentioned technical problems through the following technical means:

[0006] In a first aspect, the present invention provides a surfactant comprising the following components in parts by weight:

[0007] The mixture comprises 10-60 parts of nonionic polyoxyethylene fatty alcohol ether, 10-60 parts of anionic polyoxyethylene fatty alcohol ether sulfate, 5-40 parts of modified alkyl polysaccharide solution, 2-14 parts of additives, and 10-40 parts of water; the modified alkyl polysaccharide solution is obtained by modifying alkyl polysaccharides with haloacetic acid salts containing carboxylmethyl functional groups.

[0008] Preferably, the hydrophobic group of the nonionic polyoxyethylene fatty alcohol ether is derived from C. 10 ~C 14 Fatty alcohols, with an average number of ethylene oxide additions of 3 to 9, are terminally hydroxyl groups; the hydrophobic group of the anionic polyoxyethylene fatty alcohol ether sulfate originates from C. 10 ~C 14 Fatty alcohols have sulfates that are alkali metal salts or ammonium salts.

[0009] This invention involves compounding nonionic polyoxyethylene fatty alcohol ethers, anionic polyoxyethylene fatty alcohol ether sulfates, and carboxymethylated alkyl polysaccharides in a specific ratio, combined with a segmented dissolution and controlled feeding process, to form a tightly structured, uniformly distributed ternary composite micelle at the molecular level. The nonionic component provides flexible interface regulation and rapid wetting, the anionic component provides strong decontamination and anti-redeposition capabilities, while the carboxymethylated alkyl polysaccharides significantly enhance the system's hydrophilicity and hard water resistance through carboxyl hydration and complexation, and help stabilize the mixed micelle structure of nonionic polyoxyethylene fatty alcohol ethers / anionic polyoxyethylene fatty alcohol ether sulfates. The small-particle-size composite micelles formed through process control possess excellent interfacial stability, oil swelling capacity, and dynamic structure retention ability, thereby constructing a highly stable and synergistically enhanced surfactant system.

[0010] Preferably, the modified alkyl polysaccharide solution is prepared by: etherifying the alkyl polysaccharide with a haloacetate containing a carboxylmethyl functional group in water for 2-8 hours in the presence of an alkaline catalyst, at a reaction temperature of 40-80°C, with a reaction system pH of 10-13, and after the reaction is completed, cooling the solution to 30-50°C and adjusting the pH to 6.5-8.5 to obtain the modified alkyl polysaccharide solution.

[0011] Preferably, the molar ratio of the alkyl polysaccharide to the haloacetate containing a carboxymethyl functional group is 1:(0.5-1.0), the haloacetate containing a carboxymethyl functional group is sodium chloroacetate or potassium chloroacetate, and the alkaline catalyst is sodium hydroxide or potassium hydroxide, the amount of which is added is 0.5-5.0 wt% of the mass of the alkyl polysaccharide.

[0012] Under alkaline conditions, nucleophilic reactions can occur at the terminal ends or sugar rings of alkyl polysaccharides (APGs), where the hydroxyl groups are partially deprotonated by an alkaline catalyst to form a stronger nucleophilic center. When a haloacetate containing a carboxymethyl functional group (such as sodium chloroacetate or potassium chloroacetate) is added, the active hydroxyl group of APG undergoes nucleophilic substitution of the α-carbon atom in the haloacetate via an SN2 mechanism, replacing the chloride ion and introducing –CH2–COO into the APG molecule. - Carboxymethyl side chain. Controlling the reaction temperature between 40 and 80°C promotes ether bond formation and avoids side reactions; an alkaline environment of pH 10 to 13 ensures the APG hydroxyl group is in a more activated state, improving etherification efficiency. After the reaction, adjusting the system pH to 6.5 to 8.5 ensures the product remains stable in solution and inhibits excessive hydrolysis. Maintaining a molar ratio of alkyl polysaccharide to haloacetate of 1:(0.5 to 1.0) and an alkaline catalyst content of 0.5 to 5.0 wt% effectively balances the amount of functional group introduction, resulting in a moderate degree of modification and a structurally stable, hydrophilic, and non-gelling carboxymethylated alkyl polysaccharide solution.

[0013] Preferably, the additive includes one or more of the following components: a water-soluble organic solvent, a dispersant, and a preservative; the water-soluble organic solvent is one or both of ethanol and isopropanol, the dispersant is sodium polyacrylate, and the preservative is phenoxyethanol.

[0014] Secondly, the present invention provides a method for preparing a surfactant, wherein the method comprises:

[0015] S1. At 40–70°C, nonionic polyoxyethylene fatty alcohol ether, modified alkyl polysaccharide solution and water in the first part are mixed and stirred under shear conditions to obtain premix I;

[0016] S2. Mix the anionic polyoxyethylene fatty alcohol ether sulfate with the second part of water, stir and dissolve at 25-50℃, and adjust the pH to 6.5-8.5 to obtain pre-solution II;

[0017] S3. At 20–40°C, under shear conditions, presolution II is added to premixed solution I, while maintaining the pH at 6.5–8.5 during the addition process to obtain a surfactant concentrate;

[0018] S4. Add the additive and remaining water to the concentrate, and mature it at 20-35°C to obtain the surfactant.

[0019] Preferably, the shearing conditions in step S1 are a rotation speed of 1000-3000 rpm and a stirring time of 10-60 min; the shearing conditions in step S3 are a rotation speed of 1000-3000 rpm, the addition rate of the pre-solution II is controlled at 5-10% / min of the total addition amount, the addition time is 10-90 min, and the maturation time in step S4 is 24-48 h.

[0020] Preferably, in step S1, the first portion of water is 30-50% of the total water volume of the formula, and in step S2, the second portion of water is 30-40% of the total water volume of the formula.

[0021] The preparation method of this invention regulates the self-assembly behavior of three surfactants in the aqueous phase through segmented water addition, stepwise pre-dissolution, and controlled phase combination, thereby forming a composite micelle with a uniform structure. In step S1, the nonionic surfactant and modified alkyl polysaccharide are mixed at 40–70°C under strong shear force. The water content of the first part accounts for 30–50% of the total water volume. At this point, the system viscosity is low and the interfacial tension is reduced, which is conducive to the uniform dispersion of the two at the microscale and the formation of a stable "flexible interfacial core". In step S2, the anionic AES is dissolved independently in the second part of water (30–40%), and the pH is controlled at 6.5–8.5. This avoids the hydrolysis of the sulfate ester bond of AES under slightly acidic conditions and prevents excessive ionization with carboxymethylated APG under highly alkaline conditions, which would lead to turbidity, thus forming a stable pre-solution II. In step S3, presolution II is added to premixed solution I at a controlled rate of 5–10% / min, while maintaining the pH at 6.5–8.5. This allows AES molecules to gradually enter the A / C interfacial structure, enabling the three components to form a dense ternary composite micelle through hydrophobic interactions, hydrogen bonding, and electrostatic regulation. The final S4 curing step is carried out at 20–35°C to further stabilize the molecular arrangement of the system, homogenize the micelle size, and improve solubility and transparency. Through the synergistic control of shear strength, feeding rate, and the staged proportion of water, the system avoids salting out or gelation caused by excessively high local concentrations, ensuring that the final product has a stable interfacial structure and excellent solution stability.

[0022] Thirdly, the present invention provides an industrial cleaning agent comprising the above-mentioned surfactant.

[0023] Preferably, it also includes alkaline detergent builders, complexing agents, and rust inhibitors.

[0024] More preferably, the industrial cleaning agent comprises 10-30 parts of surfactant, 2-10 parts of alkaline detergent, 2-10 parts of complexing agent, and 1-5 parts of rust inhibitor.

[0025] The beneficial effects of this invention are:

[0026] (1) The ternary composite micelles obtained in this invention remain highly clear and non-stratified under hard water conditions. During the cleaning process, the swelling, peeling and emulsification of oil stains are significantly enhanced, and the dirt is not easy to redeposit. The system has moderate foam and is easy to rinse, making it suitable for industrial cleaning. It has good solubility and transparency over a wide temperature range. Furthermore, the introduction of carboxymethylated APG further improves the overall compatibility, safety and environmental friendliness.

[0027] (2) This invention not only improves the interfacial activity and system compatibility of APG, but also significantly enhances the comprehensive application performance of the surfactant in cleaning, hard water conditions, and over a wide temperature range. By introducing a carboxymethyl side chain, the hydrophilicity of the alkyl polysaccharide molecule is significantly improved, the intermolecular hydration ability is enhanced, and a more stable interfacial layer structure is formed in solution. The presence of the carboxyl group not only improves the solubility and low-temperature stability of APG, but also endows it with a certain complexing ability, which can react with Ca in hard water. 2+ Mg 2+ Coordination occurs, significantly improving the system's resistance to hard water and avoiding turbidity or precipitation that easily occurs when conventional APGs are mixed with anionic surfactants. Furthermore, moderate carboxymethylation reduces the aggregation tendency of APGs, making them more easily oriented at the oil-water interface and forming a denser, more stable composite micelle structure with nonionic / anionic surfactants, thereby enhancing emulsification, dispersion, and anti-redeposition properties.

[0028] (3) The ternary system of the present invention can achieve highly uniform dispersion and ordered self-assembly, significantly improving the structural stability and cleaning performance of the product. First, the high-temperature shear premixing of S1 ensures that the nonionic polyoxyethylene fatty alcohol ether and the modified alkyl polysaccharide solution (APG) form a stable interfacial core, making the subsequent introduction of anionic polyoxyethylene fatty alcohol ether sulfate (AES) smoother and avoiding the turbidity or stratification problems caused by direct collision between AES and APG in the traditional process. Second, the independent dissolution of AES and the neutral to slightly alkaline pH control maintain its good activity and prevent hydrolysis, while reducing the charge change of the system and enhancing compatibility. The controlled slow addition method can significantly reduce the salting out caused by the sudden increase in local ion concentration, making the composite micelles smaller and the structure more compact, thereby improving the emulsification, penetration and detergency. The final low-temperature curing step improves the transparency of the system, further stabilizes the micelle structure, and enhances the product's resistance to ion interference under hard water conditions. This invention achieves high stability, high homogeneity and high interfacial activity in the system, giving the surfactant superior solubility, hard water resistance, cleaning effect and safety in use. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0030] The anionic polyoxyethylene fatty alcohol ether sulfate in Examples 1-3 is anionic polyoxyethylene fatty alcohol ether sulfate sodium sulfate.

[0031] Example 1

[0032] A method for preparing a surfactant includes:

[0033] S1. At 40℃, 10kg of nonionic polyoxyethylene fatty alcohol ether, 5kg of modified alkyl polysaccharide solution and 3kg of water are mixed and stirred at 1000rpm for 60min to obtain premix I.

[0034] S2. Mix 10 kg of anionic polyoxyethylene fatty alcohol ether sulfate with 3 kg of water, stir and dissolve at 25 °C, and adjust the pH to 6.5 to obtain pre-solution II;

[0035] S3. At 20℃ and 1000 rpm, presolution II is added to premixed solution I at a rate of 5% / min of the total amount added. The pH is maintained at 6.5 during the addition process and the addition time is 10 min to obtain surfactant concentrate.

[0036] S4. Add 2 kg of additive and 4 kg of water to the concentrate and mature at 20°C for 24 h to obtain the surfactant.

[0037] The additives include 1 kg of ethanol and 1 kg of sodium polyacrylate.

[0038] The modified alkyl polysaccharide solution is prepared as follows: 20 kg of alkyl polysaccharide is etherified with 10 kg of sodium chloroacetate or potassium chloroacetate in 30.1 L of water in the presence of 0.1-1 kg of sodium hydroxide or potassium hydroxide for 8 h. The reaction temperature is 40 °C and the pH of the reaction system is 10. After the reaction is completed, the solution is cooled to 30 °C and the pH is adjusted to 6.5 to obtain 60 kg of modified alkyl polysaccharide solution.

[0039] Example 2

[0040] A method for preparing a surfactant includes:

[0041] S1. At 55℃, 35kg of nonionic polyoxyethylene fatty alcohol ether, 22.5kg of modified alkyl polysaccharide solution and 10kg of water are mixed and stirred at 2000rpm for 35min to obtain premix I;

[0042] S2. Mix 35 kg of anionic polyoxyethylene fatty alcohol ether sulfate with 8 kg of water, stir and dissolve at 38 °C, and adjust the pH to 7.5 to obtain pre-solution II;

[0043] S3. At 30℃ and 2000 rpm, presolution II is added to premixed solution I at an addition rate of 7.5% / min of the total addition amount. The pH is maintained at 7.5 during the addition process, and the addition time is 50 min to obtain surfactant concentrate.

[0044] S4. Add 8 kg of additive and 7 kg of water to the concentrate and mature at 28°C for 36 h to obtain the surfactant.

[0045] The additives include 3 kg of ethanol, 3 kg of sodium polyacrylate, and 2 kg of phenoxyethanol.

[0046] The modified alkyl polysaccharide solution was prepared by reacting 20 kg of alkyl polysaccharide with 15 kg of sodium chloroacetate or potassium chloroacetate in 35.55 L of water for 5 h in the presence of 0.55 kg of sodium hydroxide or potassium hydroxide. The reaction temperature was 60 °C and the pH of the reaction system was 12. After the reaction was completed, the solution was cooled to 40 °C and the pH was adjusted to 7.5 to obtain 71 kg of modified alkyl polysaccharide solution.

[0047] Example 3

[0048] A method for preparing a surfactant includes:

[0049] S1. At 70℃, 60kg of nonionic polyoxyethylene fatty alcohol ether, 40kg of modified alkyl polysaccharide solution and 10kg of water are mixed and stirred at 3000rpm for 10min to obtain premix I.

[0050] S2. Mix 60 kg of anionic polyoxyethylene fatty alcohol ether sulfate with 8 kg of water, stir and dissolve at 50 °C, and adjust the pH to 8.5 to obtain pre-solution II;

[0051] S3. At 40℃ and 3000 rpm, presolution II is added to premixed solution I at an addition rate of 10% / min of the total addition amount. The pH is maintained at 8.5 during the addition process, and the addition time is 90 min to obtain surfactant concentrate.

[0052] S4. Add 14 kg of additive and 7 kg of water to the concentrate, and mature at 35°C for 48 h to obtain the surfactant.

[0053] The additives include 6 kg of ethanol and 4 kg of sodium polyacrylate.

[0054] The modified alkyl polysaccharide solution was prepared by reacting 20 kg of alkyl polysaccharide with 20 kg of sodium chloroacetate or potassium chloroacetate in 41 kg of water for 2 h in the presence of 1 kg of sodium hydroxide or potassium hydroxide. The reaction temperature was 80 °C and the pH of the reaction system was 13. After the reaction was completed, the solution was cooled to 50 °C and the pH was adjusted to 8.5 to obtain 82 kg of modified alkyl polysaccharide solution.

[0055] Comparative Example 1

[0056] The formulation was the same as in Example 2. All components were added to the same container at once and stirred at 40°C for 60 minutes. No stepwise premixing (S1 / S2) or controlled feeding was performed, and the pH and moisture content during the feeding process were not controlled. The sample of Comparative Example 1 was obtained by directly cooling to room temperature.

[0057] Comparative Example 2

[0058] The difference from Example 2 is that the "modified alkyl polysaccharide solution" was replaced with the "ordinary alkyl polysaccharide solution", while the rest remained the same.

[0059] Comparative Example 3

[0060] The difference from Example 2 is that steps S2 and S3 do not involve precise pH control.

[0061] Comparative Example 4

[0062] The difference from Example 2 is that the modified alkyl polysaccharide solution was removed.

[0063] To verify the material properties of Examples 1-3 and Comparative Examples 1-4, the following tests were conducted using the following methods:

[0064] (1) Interfacial tension test

[0065] The equilibrium interfacial tension of the sample (1 wt% aqueous solution) was determined at 25±0.5℃ according to GB / T 5549-2019 "Determination of surface tension".

[0066] (2) Emulsifying power test

[0067] According to the provisions of QB / T 5186-2017 "Determination of Emulsifying Properties of Surfactants", the height of the emulsion layer and its stability at 30 min and 60 min after mixing the sample (1wt% solution) with the standard oil (such as mineral oil) at 25℃ were determined by graduated cylinder method.

[0068] (3) Hard water stability test

[0069] According to the hard water stability test procedure in GB / T34684-2017 "Surfactant Stability Test Method", the sample (1wt% solution) was prepared using simulated hard water (CaCO3 300–500 mg / L), and its turbidity, precipitation and stratification were observed after standing at 25℃ for 24 h.

[0070] (4) Foam performance test

[0071] The initial foam height and 5-minute foam retention height of the sample were determined according to GB / T 7462-2023 "Determination of foaming power of surfactants - Modified Ross-Miles method".

[0072] Performance data is shown in Table 1.

[0073] Table 1

[0074]

[0075] As shown in the table, the samples in Examples 1-3 were all transparent or microemulsion liquids, without stratification or precipitation, and the system appearance was stable. Regarding interfacial tension, Example 2 was lower than the samples in Comparative Examples 1-3, indicating that the surfactant system of this invention has a stronger ability to reduce interfacial tension at the oil-water interface, which is beneficial for oil wetting and diffusion. Regarding emulsifying power, Example 2 was higher than Comparative Examples 1-4, indicating that the ternary composite micelles constructed in this invention have a stronger ability to coat and disperse oil. Regarding hard water stability, Example 2 was lower than Comparative Examples 1-4, which exhibited salting out and micelle destruction. The foam height of Examples 1-3 of this invention was moderate, and the 5-minute retention rate was low, meeting the requirements of industrial cleaning for "easy rinsing and no excessive residual foam." The foam stability of Example 2 was much lower than that of Comparative Example 1 because the formed composite micelles are macromolecular aggregates with an antifoaming effect. Comparative Examples 3 and 4 had high foam retention rates, which were not conducive to foam control during cleaning.

[0076] The surfactants prepared in Examples 1-3 and Comparative Examples 1-4 were formulated into industrial cleaning agents. The original components of the industrial cleaning agents are as follows: 20 kg of surfactant, 6 kg of alkaline detergent (sodium carbonate), 6 kg of complexing agent (sodium tripolyphosphate), and 3 kg of rust inhibitor (sodium molybdate).

[0077] The performance of the prepared industrial cleaning agent was tested according to JB / T4323.2-2019 "Test Methods for Water-based Metal Cleaning Agents".

[0078] The performance results are shown in Table 2.

[0079]

[0080] As shown in Table 2, the cleaning agents formulated using the surfactant system of this invention in Examples 1-3 all exhibited excellent cleaning performance and metal compatibility under specified conditions. Among them, the static immersion cleaning rate and spray cleaning rate of Example 2 were higher than those of Comparative Examples 1-4. Examples 1-3 all achieved a grade of 0 in the HT200 cast iron rust prevention test, with no rust spots. The corrosion rate of 45 steel was significantly lower than that of Comparative Examples 1-4. This was because Comparative Example 3 did not control the pH, which led to the hydrolysis of AES and the generation of corrosive byproducts, resulting in a higher corrosion rate in Comparative Example 3. At the same time, Examples 1-3 had a lower foam retention height and no turbidity or sedimentation in hard water. This indicates that by introducing modified alkyl polysaccharides and a ternary compound structure, this invention effectively improves the rust prevention, corrosion resistance, and hard water stability of water-based metal cleaning agents while ensuring high detergency.

[0081] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention. Technical aspects, shapes, and structures not described in detail in this invention are all well-known technologies.

Claims

1. A surfactant, characterized in that, The components include the following parts by weight: The mixture comprises 10-60 parts of nonionic polyoxyethylene fatty alcohol ether, 10-60 parts of anionic polyoxyethylene fatty alcohol ether sulfate, 5-40 parts of modified alkyl polysaccharide solution, 2-14 parts of additives, and 10-40 parts of water; wherein the modified alkyl polysaccharide solution is obtained by modifying alkyl polysaccharides with haloacetates containing carboxymethyl functional groups.

2. The surfactant according to claim 1, characterized in that, The hydrophobic group of the nonionic polyoxyethylene fatty alcohol ether originates from C. 10 ~C 14 Fatty alcohols, with an average number of ethylene oxide additions of 3 to 9, are terminally hydroxyl groups; the hydrophobic group of the anionic polyoxyethylene fatty alcohol ether sulfate originates from C. 10 ~C 14 Fatty alcohols have sulfates that are alkali metal salts or ammonium salts.

3. A surfactant according to claim 1, characterized in that, The modified alkyl polysaccharide solution is prepared by: etherifying the alkyl polysaccharide with a haloacetate containing a carboxylmethyl functional group in water for 2-8 hours in the presence of an alkaline catalyst, at a reaction temperature of 40-80℃ and a pH of 10-13. After the reaction, the solution is cooled to 30-50℃ and the pH is adjusted to 6.5-8.5 to obtain the modified alkyl polysaccharide solution.

4. A surfactant according to claim 3, characterized in that, The molar ratio of the alkyl polysaccharide to the haloacetate containing a carboxyl functional group is 1:(0.5-1.0), the haloacetate containing a carboxyl functional group is sodium chloroacetate or potassium chloroacetate, and the alkaline catalyst is sodium hydroxide or potassium hydroxide, the amount of which is added is 0.5-5.0 wt% of the mass of the alkyl polysaccharide.

5. A surfactant according to claim 1, characterized in that, The additive includes one or more of the following components: water-soluble organic solvent, dispersant, and preservative; the water-soluble organic solvent is one or both of ethanol and isopropanol, the dispersant is sodium polyacrylate, and the preservative is phenoxyethanol.

6. A method for preparing a surfactant, for preparing the surfactant according to any one of claims 1-5, characterized in that, The preparation method includes: S1. At 40–70°C, nonionic polyoxyethylene fatty alcohol ether, modified alkyl polysaccharide solution and water in the first part are mixed and stirred under shear conditions to obtain premix I; S2. Mix the anionic polyoxyethylene fatty alcohol ether sulfate with the second part of water, stir and dissolve at 25-50℃, and adjust the pH to 6.5-8.5 to obtain pre-solution II; S3. At 20–40°C, under shear conditions, presolution II is added to premixed solution I, while maintaining the pH at 6.5–8.5 during the addition process to obtain a surfactant concentrate; S4. Add the additive and remaining water to the concentrate, and mature it at 20-35°C to obtain the surfactant.

7. The method for preparing a surfactant according to claim 6, characterized in that, The shearing conditions in step S1 are a rotation speed of 1000-3000 rpm and a stirring time of 10-60 min; the shearing conditions in step S3 are a rotation speed of 1000-3000 rpm, the addition rate of the pre-solution II is controlled at 5-10% / min of the total addition amount, and the addition time is 10-90 min; the maturation time in step S4 is 24-48 h.

8. The method for preparing a surfactant according to claim 6, characterized in that, In step S1, the first portion of water is 30-50% of the total water volume of the formula, and in step S2, the second portion of water is 30-40% of the total water volume of the formula.

9. An industrial cleaning agent, characterized in that, It includes the surfactant described in any one of claims 1-5.

10. An industrial cleaning agent according to claim 9, characterized in that, It also includes alkaline detergent builders, complexing agents, and rust inhibitors.

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