A biomimetic amphoteric surfactant, its preparation method and application

Abstract

The application relates to the technical field of fine chemicals, in particular to a biomimetic amphoteric surfactant as well as a preparation method and application thereof; the preparation method of the biomimetic amphoteric surfactant comprises the following steps: reacting a fatty amine polyoxyethylene ether with a halogenated hydrocarbon to obtain a benzyl quaternary ammonium salt intermediate; cooling the benzyl quaternary ammonium salt intermediate, then adding phosphorus pentoxide to react; after the addition is completed, water is added, the reaction is continuously carried out, and the biomimetic amphoteric surfactant is obtained; the biomimetic amphoteric surfactant simultaneously integrates three characteristics of phosphate anion, polyether non-ion and benzyl quaternary ammonium salt cation, effectively solves the industry problem that traditional phosphates and cationic settling agents are incompatible, and is applied to metal processing fluid, can realize stable compounding with cationic settling agents while retaining excellent extreme pressure lubricity and hard water resistance, and can replace traditional extreme pressure agents such as environmentally-unfriendly chlorinated paraffin.

Description

Technical Field

[0001] This application relates to the technical field of fine chemicals, and in particular to a biomimetic amphoteric surfactant, its preparation method, and its application. Background Technology

[0002] Metalworking fluids are key process fluids in modern manufacturing, with core functions including cooling, lubrication, cleaning, rust prevention, and the settling and separation of machining debris. To meet these functions, formulations typically require a combination of additives, including: anionic phosphate surfactants that provide extreme pressure anti-wear and cleaning capabilities; nonionic surfactants that provide emulsification, wetting, and hard water resistance; and cationic polymer flocculants that promote the flocculation and sedimentation of impurities.

[0003] However, a strong electrostatic interaction exists between traditional anionic phosphate esters and cationic flocculants, leading to turbidity, precipitation, and even demulsification in the formulation system, severely limiting the performance and stability of the formulation. This fundamental incompatibility forces formulation design into a dilemma: first, abandoning highly efficient phosphate ester extreme pressure agents and instead using chlorinated paraffins or sulfurized oils with unpleasant odors and unstable performance, which pose higher environmental and toxic risks; second, sacrificing the system's cleaning and maintenance capabilities, resulting in a shortened processing fluid life. Furthermore, traditional phosphate ester surfactants are quite sensitive to hard water ions and often have poor environmental degradation properties.

[0004] Phospholipids, such as phosphatidylcholine, are basic amphipathic molecules that make up cell membranes. Their structure simultaneously contains hydrophobic long chains, hydrophilic phosphate anionic groups, and choline quaternary ammonium salt cationic groups. This unique "anionic-cationic" internal salt structure allows them to exist stably in complex ionic environments and exhibits excellent biocompatibility and degradability.

[0005] While existing technologies involve the synthesis of phosphorus-containing surfactants, most products are single anionic or nonionic types, failing to address compatibility issues with cationic auxiliaries. A few studies have attempted to synthesize amphoteric phosphates, but these methods suffer from complex synthetic routes, high costs, or uncontrollable product structures, making them unsuitable for industrial production and large-scale applications. For example, directly using solid choline for phosphorylation presents problems such as poor solubility, heterogeneous reactions, numerous byproducts, and low selectivity for the target product.

[0006] Therefore, finding a novel surfactant that is well compatible with cationic components while also possessing excellent lubrication, extreme pressure properties, and hard water resistance has become a pressing technical challenge in the field of metalworking fluids. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this application provides a biomimetic amphoteric surfactant, its preparation method, and its application; specifically, it relates to an amphoteric surfactant based on a biomimetic phospholipid structure that possesses anionic, nonionic, and cationic properties, and its preparation method.

[0008] This application provides a biomimetic amphoteric surfactant with a simple synthetic route, mild conditions, controllable product structure, and excellent performance.

[0009] This application further relates to the application of this biomimetic amphoteric surfactant as a high-performance multifunctional additive in water-based metalworking fluids (such as cutting fluids, grinding fluids, and rolling fluids), and is particularly suitable for complex formulation systems that need to simultaneously meet requirements such as extreme pressure lubrication, compatibility with cationic flocculants, hard water stability, and environmental friendliness.

[0010] In a first aspect, this application provides a method for preparing a biomimetic amphoteric surfactant, employing the following technical solution: A method for preparing a biomimetic amphoteric surfactant includes the following steps: (1) Aliphatic amine polyoxyethylene ether is reacted with a haloalkanes to obtain a benzyl quaternary ammonium salt intermediate; (2) After cooling the benzyl quaternary ammonium salt intermediate, phosphorus pentoxide is added to carry out the reaction; (3) Heat up, add water, and continue the reaction to obtain a biomimetic amphoteric surfactant.

[0011] By adopting the above technical solution, this application quaternizes fatty amine polyoxyethylene ether with halogenated hydrocarbons to form a benzyl quaternary ammonium salt intermediate with nonionic segments, and then phosphorylates it with phosphorus pentoxide to obtain a biomimetic amphoteric surfactant, which is a mixture containing phosphate monoester salt and phosphate diester salt; the molar ratio of phosphate monoester salt to phosphate diester salt in the mixture is 3:7 to 7:3.

[0012] Preferably, in step (1), the fatty amine polyoxyethylene ether is prepared by reacting a straight-chain or branched fatty amine with 8-18 carbon atoms with ethylene oxide via an addition reaction; wherein the number of additions of ethylene oxide is 5-20.

[0013] Preferably, the haloalkane in step (1) is benzyl chloride.

[0014] Preferably, the reaction temperature in step (1) is 100-120°C and the reaction time is 4-6 hours.

[0015] Preferably, the temperature of the benzyl quaternary ammonium salt intermediate after cooling in step (2) is 0-25℃.

[0016] Preferably, in step (2), during the reaction of adding phosphorus pentoxide, the temperature of the reaction system is controlled to be below 40°C.

[0017] Preferably, in step (3), the temperature after heating is 60-100℃.

[0018] Preferably, in step (3), the reaction continues for 2-4 hours.

[0019] Preferably, in step (1), the equivalence ratio of amino group to haloalkanes is 1:(0.95-1.05). Preferably, in step (2), the molar ratio of phosphorus pentoxide to benzyl quaternary ammonium salt intermediate is (0.4-0.65):1.

[0020] Preferably, the molar ratio of phosphorus pentoxide in step (2) to water in step (3) is 1:(0.95-1.05).

[0021] In one specific feasible implementation, a method for preparing a biomimetic amphoteric surfactant includes the following steps: Step 1: Quaternization reaction of fatty amine polyoxyethylene ether intermediate A fatty amine polyoxyethylene ether is prepared by reacting straight-chain or branched fatty amines with 8-18 carbon atoms with ethylene oxide in an addition reaction, wherein the addition number of ethylene oxide is 5-20.

[0022] Add 0.95-1.05 equivalents of haloalkanes to fatty amine polyoxyethylene ethers and reflux at 100-120°C for 4-6 hours to obtain benzyl quaternary ammonium salt intermediates.

[0023] Preferably, the haloalkane is benzyl chloride.

[0024] Preferably, the equivalence ratio of amino group to haloalkanes is 1:1.

[0025] Step 2: Controlled phosphorylation reaction of quaternary ammonium salt intermediate The benzyl quaternary ammonium salt intermediate obtained in step one is cooled to 0-25℃, and phosphorus pentoxide is added to it in batches and slowly. The total amount of phosphorus pentoxide added is the key to controlling the ratio of phosphate monoester to phosphate diester in the final product (i.e., biomimetic amphoteric surfactant). The molar ratio of the total amount of phosphorus pentoxide added to the benzyl quaternary ammonium salt intermediate is (0.4-0.65):1.

[0026] The addition of phosphorus pentoxide must be slow, and the reaction temperature must be kept below 40°C to prevent violent exothermic reactions that could lead to local overheating, polyether chain degradation, or product charring.

[0027] After phosphorus pentoxide is added, the reaction system is gradually heated to 60-100℃, water is added, and the reaction continues at this temperature for 2-4 hours to obtain the final product.

[0028] Preferably, the molar ratio of phosphorus pentoxide to water is 1:(0.95-1.05).

[0029] More preferably, the molar ratio of phosphorus pentoxide to water is 1:1.

[0030] By adopting the above technical solution, this application uses fatty amine polyoxyethylene ether as a starting agent, introduces a cationic center through benzyl quaternization, and then carries out a controlled phosphorylation reaction with phosphorus pentoxide. This route cleverly solves the problems of raw material miscibility and reaction homogeneity. Furthermore, by precisely controlling the amount of phosphorus pentoxide added, a biomimetic amphoteric surfactant, namely a mixture containing monophosphate and diester, can be obtained. The product prepared does not contain triphosphate.

[0031] The final product molecule simultaneously integrates: Anionic centers: provided by phosphate mono / diester groups, which endow the product with excellent extreme pressure anti-wear properties, rust prevention and cleaning and emulsifying ability for oil stains.

[0032] Nonionic segments: provided by ethylene oxide (EO) chains, giving the product excellent resistance to hard water, solubilization ability and environmental temperature adaptability.

[0033] The cation center is provided by a benzyl quaternary ammonium salt group, which is stably linked to the molecular skeleton by chemical bonds. This group can effectively shield the negative charge of phosphate ions, fundamentally solving the electrostatic incompatibility problem with added cationic flocculants, and also bringing certain antibacterial properties.

[0034] The biomimetic amphoteric surfactant prepared in this application not only solves the problem of incompatibility of existing formulations, but its modular structure also allows for precise control of the hydrophilic-lipophilic balance (HLB) and application performance of the product by adjusting the hydrophobic chain length, EO chain length and the degree of phosphorylation, thereby meeting the needs of different metal processing scenarios from light load to heavy load and from rough processing to fine processing.

[0035] Secondly, this application provides a biomimetic amphoteric surfactant, employing the following technical solution: A biomimetic amphoteric surfactant, wherein the biomimetic amphoteric surfactant is prepared by the above method.

[0036] Thirdly, this application provides an application of a biomimetic amphoteric surfactant in the preparation of water-based metalworking fluids, employing the following technical solution: Application of a biomimetic amphoteric surfactant in the preparation of water-based metalworking fluids.

[0037] Preferably, the amount of biomimetic amphoteric surfactant added is 1%-10.0% of the total mass of the metalworking fluid.

[0038] By adopting the above technical solution, biomimetic amphoteric surfactants are applied to metalworking fluids, and the resulting metalworking fluids have good lubricity, defoaming properties, sedimentation properties, and rust prevention properties; while retaining excellent extreme pressure lubricity and hard water resistance, they can achieve stable compounding with cationic sedimentation agents.

[0039] In one specific feasible implementation, the biomimetic amphoteric surfactant of this application is used as a multifunctional additive in metalworking fluids.

[0040] The biomimetic amphoteric surfactant prepared in this application is added at an amount of 1.0% to 10.0% of the total formulation mass and compounded with other additives such as rust inhibitors, lubricants, defoamers, bactericides and cationic flocculants (such as polydiallyldimethylammonium chloride) to prepare a high-performance water-based metalworking fluid.

[0041] This metalworking fluid has the following outstanding advantages: Excellent formulation compatibility: The pre-placed cationic center within the biomimetic amphoteric surfactant molecule effectively neutralizes the negative charge of phosphate, enabling it to coexist stably with added cationic flocculants without precipitation or stratification during long-term storage.

[0042] Excellent extreme pressure lubrication properties: Phosphate groups can decompose and react with the metal surface under high temperature and pressure of friction pair to form a chemical protective film of iron phosphate, providing excellent extreme pressure anti-wear and friction reduction performance.

[0043] Strong resistance to hard water: The hydrophilic polyoxyethylene ether (EO) segments in the molecule make it insensitive to polyvalent metal ions such as calcium and magnesium, and it still maintains stable performance under hard water conditions.

[0044] Good biodegradability and environmental friendliness: Compared with chlorinated paraffins and sulfurized oils, the structure of the product of this application is closer to that of natural substances, and it is expected to have better environmental compatibility and biodegradability.

[0045] Multifunctional integration: A single additive can simultaneously provide multiple functions such as lubrication, emulsification, cleaning, and sedimentation assistance, simplifying the formulation system.

[0046] In summary, this application includes at least one of the following beneficial technical effects: This application uses fatty amine polyoxyethylene ether to quaternize via halogenated hydrocarbons to form a benzyl quaternary ammonium salt intermediate with nonionic segments, which is then phosphorylated with phosphorus pentoxide to obtain a biomimetic amphoteric surfactant. The biomimetic amphoteric surfactant prepared in this application integrates the characteristics of phosphate ester anionic, polyether nonionic, and benzyl quaternary ammonium salt cationic surfactants, effectively solving the industry problem of incompatibility between traditional phosphate esters and cationic flocculants. When the biomimetic amphoteric surfactant is applied to metalworking fluid, the prepared metalworking fluid has good lubricity, defoaming, sedimentation and rust prevention properties, while achieving stable compounding with cationic flocculants. The synthetic route of this application is simple, the conditions are mild, and the product structure is tunable, which has important industrial application value. Detailed Implementation

[0047] The technical solutions of this application are further illustrated by specific embodiments below. These specific embodiments do not represent a limitation on the scope of protection of this application. Any non-essential modifications and adjustments made by others based on the concept of this application still fall within the scope of protection of this application.

[0048] All raw materials involved in this application are commercially available products, among which, Tricarboxylic acid, purchased from BASF L190 PLUS; Sebacic acid, purchased from Shandong Kaisai Biotechnology Co., Ltd.; Triethanolamine, phosphate ester, and blank sample (pure water) were all purchased from BASF Yangtze. Dihydroxyethylcyclohexylamine, CAS: 4500-29-2; 22# naphthenic base oil, purchased from Karamay Refinery; Genifol 6062, Nanjing Shangqin New Materials Technology Co., Ltd.; Chlorinated paraffin, Shandong Xinheng Chemical Co., Ltd.; Trimethylolpropane oleate, Shandong Ruijie New Materials Co., Ltd.; BIT-20 fungicide, Itofuku Biotechnology (Shanghai) Co., Ltd.; Busan 77 settling agent, Buckman; 1247 defoamer, Dow Corning; Tallowamine, CAS No. 61790-33-8; The present application will be further described in detail below with reference to embodiments and comparative examples.

[0049] Preparation Example 1:

[0050] The preparation method of laurylamine polyoxyethylene (9) ether is as follows: Add 185g of laurylamine to the reactor, evacuate, and purge with nitrogen three times; raise the temperature to 100℃, add 396g of ethylene oxide to the reactor in multiple portions, and control the reaction temperature of the reaction system to be below 110℃; after the ethylene oxide has been completely introduced, continue the reaction and aging for 1 hour to obtain laurylamine polyoxyethylene (9) ether.

[0051] Preparation Example 2:

[0052] The preparation method of tallow amine polyoxyethylene (15) ether is as follows: Add 269.5g of tallow amine to the reactor, evacuate, and purge with nitrogen three times; raise the temperature to 100℃, add 660g of ethylene oxide to the reactor in multiple portions, and control the reaction temperature of the reaction system to be below 110℃; after the ethylene oxide has been completely introduced, continue the reaction and aging for 1 hour; and obtain tallow amine polyoxyethylene (15) ether.

[0053] Preparation Example 3:

[0054] The preparation method of isooctylamine polyoxyethylene (7) ether is as follows: 129g of isooctylamine was added to the reactor, the vacuum was drawn, and nitrogen was introduced to replace it 3 times; the temperature was raised to 100℃, and 308g of ethylene oxide was added to the reactor in multiple portions, controlling the reaction temperature of the reaction system to be below 110℃; after the ethylene oxide was completely introduced, the reaction was continued for aging for 1 hour to obtain isooctylamine polyoxyethylene (7) ether.

[0055] Example 1:

[0056] 1. Quaternization reaction of fatty amine polyoxyethylene ether intermediates In a 500 mL four-necked flask equipped with a stirrer, thermometer, and reflux condenser, add 0.1 mol laurylamine polyoxyethylene (9) ether; start stirring and add 0.1 mol benzyl chloride (the equivalence ratio of amino to benzyl chloride is 1:1); heat the reaction system to 110 °C and stir and reflux at this temperature for 5 hours; after the reaction is completed, a pale yellow to amber viscous liquid is obtained, which is the benzyl quaternary ammonium salt intermediate, which can be used directly in the next step of the reaction without purification.

[0057] Laurethamine polyoxyethylene (9) ether was prepared by Preparation Example 1.

[0058] 2. Controlled phosphorylation reaction of quaternary ammonium salt intermediates The flask containing the benzyl quaternary ammonium salt intermediate was placed in an ice-water bath and cooled to 10°C with stirring. Under vigorous stirring and effective cooling, 0.05 mol of phosphorus pentoxide powder (molar ratio of phosphorus pentoxide to benzyl quaternary ammonium salt intermediate was 0.5:1) was added very slowly in batches using a solid feeder. The feeding rate was controlled to maintain the reaction system temperature at 35°C throughout the process, which took approximately 1.5 hours.

[0059] After the addition of materials is complete, remove the ice-water bath and gradually heat the reaction system to 70°C with stirring. Maintain the temperature at 70°C and slowly add 0.05 mol of deionized water dropwise through a constant-pressure dropping funnel. The water addition process is exothermic, so the dropping rate needs to be controlled to maintain a stable temperature.

[0060] After adding water, the mixture was kept at 70°C with stirring for 3 hours. After the reaction was complete, a brownish-red viscous liquid product was obtained, which is the biomimetic amphoteric surfactant.

[0061] Example 2:

[0062] 1. Quaternization reaction of fatty amine polyoxyethylene ether intermediates In the reaction vessel, 0.2 mol of tallow amine polyoxyethylene (15) ether was added; stirring was started and 0.2 mol of benzyl chloride (the equivalent ratio of amino to benzyl chloride was 1:1) was added; the reaction system was heated to 100°C and stirred and refluxed at this temperature for 6 hours. After the reaction was completed, benzyl quaternary ammonium salt intermediate was obtained.

[0063] The tallow amine polyoxyethylene (15) ether was prepared by Preparation Example 2.

[0064] 2. Controlled phosphorylation reaction of quaternary ammonium salt intermediates The flask containing the benzyl quaternary ammonium salt intermediate was placed in an ice-water bath and cooled to 0°C with stirring. Under vigorous stirring and ice-water bath cooling, 0.13 mol of phosphorus pentoxide (molar ratio of phosphorus pentoxide to benzyl quaternary ammonium salt intermediate was 0.65:1) was slowly added in batches; the temperature of the reaction system was maintained at 38°C throughout the process, and the entire addition process took about 1 hour.

[0065] After the addition of the feed is complete, the reaction system is heated to 60°C, and 0.13 mol of deionized water is slowly added. The reaction is then continued at 60°C for 4 hours. After the reaction is complete, a dark brown viscous product is obtained, which is the biomimetic amphoteric surfactant.

[0066] Example 3:

[0067] 1. Quaternization reaction of fatty amine polyoxyethylene ether intermediates In the reaction flask, 0.15 mol of isooctamine polyoxyethylene (7) ether was added, and stirring was started. 0.15 mol of benzyl chloride (the equivalent ratio of amino to benzyl chloride was 1:1) was added. The reaction system was heated to 120°C and stirred under reflux for 4.5 hours. After the reaction was completed, benzyl quaternary ammonium salt intermediate was obtained.

[0068] The isooctylamine polyoxyethylene (7) ether was prepared by Preparation Example 3.

[0069] 2. Controlled phosphorylation reaction of quaternary ammonium salt intermediates The flask containing the benzyl quaternary ammonium salt intermediate was placed in an ice-water bath and cooled to 25°C with stirring. Under stirring and cold water circulation cooling, 0.06 mol of phosphorus pentoxide (molar ratio of phosphorus pentoxide to benzyl quaternary ammonium salt intermediate was 0.4:1) was slowly added in batches; the temperature of the reaction system was maintained at 30°C throughout the process, and the entire feeding process took about 2 hours.

[0070] After the addition of the materials is complete, the reaction system is heated to 80°C and 0.06 mol of deionized water is added quickly. The reaction is then carried out at 80°C for 2 hours. After the reaction is complete, a reddish-brown viscous liquid is obtained, which is the biomimetic amphoteric surfactant.

[0071] Application performance testing:

[0072] The biomimetic amphoteric surfactants prepared in the above embodiments were added to the metalworking fluid in the following proportions to prepare the metalworking fluid, as shown in Table 1.

[0073] Table 1. Composition of Metalworking Fluid Raw Materials

[0074]

[0075] The performance of the metalworking fluid prepared by the above formula was tested. The testing methods and results are as follows: 1. PB Lubrication Test: The test was conducted according to GB / T 3142-2019 "Determination of Carrying Capacity of Lubricants - Four-Ball Method"; Testing machine: Four-ball friction tester; testing conditions: 10s, 1450rpm, room temperature.

[0076] The higher the Pb grade in the test results, the better its lubricity.

[0077] 2. Tapping lubrication test (tapping torque value): Test machine: TTT-Microtap tapping torque machine, 1500rpm, hole depth 12mm, cutter M4F, 7075 aluminum alloy sheet.

[0078] The smaller the tapping torque value in the test results, the better its lubrication.

[0079] 3. Foam test method (cyclic bubbling method): Testing instrument: Guangdong Platinum Metalworking Fluid Stability Tester, model: BSV-11; Test method: (1) Add 10% of the metalworking fluid sample to the test plan and stir until the reaction is uniform; (2) Dilute 50ml of each solution with tap water (water hardness 125ppm) at a ratio of 5% and pour into a 100ml stoppered graduated cylinder; (3) Shake the stoppered graduated cylinder up and down 60 times at a frequency of 120 times / min, and record the foam height and defoaming time after letting it stand.

[0080] 4. Settlement test method Pour 1g of iron powder into 50ml of test solution, immediately tighten the stopper of the graduated cylinder, place it in a constant temperature shaker, and shake horizontally for 30s (frequency 250 times / min, amplitude 25mm) to ensure that the iron powder and test solution are fully mixed (no obvious agglomeration can be observed with the naked eye). After shaking, quickly fix the graduated cylinder vertically to the support and start timing immediately until the sedimentation interface stabilizes at the bottom of the graduated cylinder, and observe the sedimentation time.

[0081] 5. The results of the iron filings corrosion resistance test (rust prevention experiment) are as follows: The test was conducted according to IP287, "Determination of rust prevention properties of water-soluble metalworking fluids - Iron filings / filter paper method": Test method: Add the metalworking fluid sample to the test solution at a ratio of 10%, stir and react evenly to obtain the test sample; Dilute each sample with tap water at a ratio of 5% (water hardness 125ppm) and test them using the iron filings rust prevention test method (IP287). Result determination: No rust spots: Level 0; Several rust spots: Level 1; Ten or more rust spots: Level 2; Dozens of rust spots: Level 3; Severe corrosion: Level 4 Table 2 Application Test Results

[0082] As shown in Table 2, the biomimetic amphoteric surfactants prepared using the methods of Examples 1-3, when added to the metalworking fluid as extreme pressure agents, produce metalworking fluids with good lubricity, defoaming properties, sedimentation properties, and rust prevention properties. This indicates that the metalworking fluids prepared using the biomimetic amphoteric surfactants of this application as raw materials can achieve stable compounding with cationic sedimentation agents while retaining excellent extreme pressure lubricity and hard water resistance.

[0083] In Comparative Example 1, the additive prepared from phosphate ester was added to the metalworking fluid as an extreme pressure agent. The additive prepared was incompatible with the flocculant. This was because the added phosphate ester was incompatible with the anion and cation and could not be used simultaneously with the flocculant Busan 77.

[0084] Based on the test results of Examples 1-3 and Comparative Example 2, it can be seen that the metalworking fluid prepared using the biomimetic amphoteric surfactant of this application as raw material effectively improves the lubricity of the metalworking fluid.

[0085] In Comparative Example 3, the additive prepared from chlorinated paraffin was added to the metalworking fluid as an extreme pressure agent. Although chlorinated paraffin is compatible with the flocculant Busan 77 and the prepared metalworking fluid has lubrication and defoaming properties, chlorinated paraffin releases a large amount of chloride ions in water, which is corrosive to metals and has poor corrosion performance.

[0086] The technical features of the above-described embodiments and examples can be combined in any suitable manner. For the sake of brevity, not all possible combinations of the technical features in the above-described embodiments and examples are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0087] The embodiments described above are merely illustrative of several implementation methods of this application, intended to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Furthermore, it should be understood that after reading the above teachings of this application, those skilled in the art can make various alterations or modifications to this application, and the equivalent forms obtained also fall within the scope of protection of this application. It should also be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing a biomimetic amphoteric surfactant, characterized in that: Includes the following steps: (1) Aliphatic amine polyoxyethylene ether is reacted with a haloalkanes to obtain a benzyl quaternary ammonium salt intermediate; (2) After cooling the benzyl quaternary ammonium salt intermediate, phosphorus pentoxide is added to carry out the reaction; (3) Heat up, add water, and continue the reaction to obtain a biomimetic amphoteric surfactant.

2. The method for preparing a biomimetic amphoteric surfactant according to claim 1, characterized in that: In step (1), the fatty amine polyoxyethylene ether is prepared by reacting a straight-chain or branched fatty amine with 8-18 carbon atoms with ethylene oxide in an addition reaction; wherein the number of additions of ethylene oxide is 5-20.

3. The method for preparing a biomimetic amphoteric surfactant according to claim 1, characterized in that: In step (1), the halogenated hydrocarbon is benzyl chloride.

4. The method for preparing a biomimetic amphoteric surfactant according to claim 1, characterized in that: The reaction temperature in step (1) is 100-120℃, and the reaction time is 4-6 hours.

5. The method for preparing a biomimetic amphoteric surfactant according to claim 1, characterized in that: The temperature of the benzyl quaternary ammonium salt intermediate after cooling in step (2) is 0-25℃; In step (2), during the reaction of adding phosphorus pentoxide, the temperature of the reaction system is controlled to be below 40°C.

6. The method for preparing a biomimetic amphoteric surfactant according to claim 1, characterized in that: In step (3), the temperature after heating is 60-100℃; In step (3), the reaction continues for 2-4 hours.

7. The method for preparing a biomimetic amphoteric surfactant according to claim 1, characterized in that: In step (1), the equivalence ratio of amino group to haloalkanes is 1:(0.95-1.05). In step (2), the molar ratio of phosphorus pentoxide to benzyl quaternary ammonium salt intermediate is (0.4-0.65):1; The molar ratio of phosphorus pentoxide in step (2) to water in step (3) is 1:(0.95-1.05).

8. A biomimetic amphoteric surfactant, characterized in that: The biomimetic amphoteric surfactant is prepared by the method described in any one of claims 1-7.

9. The application of the biomimetic amphoteric surfactant prepared by the method of any one of claims 1-7, or the biomimetic amphoteric surfactant of claim 8, in the preparation of metalworking fluids.

10. The application according to claim 9, characterized in that: The amount of the biomimetic amphoteric surfactant added is 1%-10% of the total mass of the metalworking fluid.

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