Cutting fluid for metal processing and preparation method thereof

Abstract

The present application relates to the technical field of cutting fluids, and in particular to a metalworking cutting fluid and a preparation method thereof. The metalworking cutting fluid of the present application comprises water, a modified surfactant, a hydrogel, a rust inhibitor, an antibacterial agent and a pH regulator. During preparation, the rust inhibitor and the pH regulator are first reacted, and then the hydrogel, the modified surfactant and the antibacterial agent are added to form a cross-linked hydrogel; the modified surfactant can form nanomicelles in an aqueous solution, and has an aldehyde end-capping, reacts with the hydrogel to form imine bond crosslinking points, improves the rust prevention, corrosion resistance and antibacterial properties of the cutting fluid at low pH values, effectively reduces the deterioration of the cutting fluid, and increases the service life of the cutting fluid; in addition, a layer of graphene oxide is introduced into the hydrogel and a polymer is grafted, which further improves the cooling performance, rust prevention, corrosion resistance and lubrication performance of the cutting fluid.

Description

Technical Field

[0001] The present application relates to the technical field of cutting fluids, and in particular to a cutting fluid for metal processing and a preparation method thereof. Background Art

[0002] In the metal cutting process, cutting fluid, as an important auxiliary material, has multiple functions such as cooling, lubrication, rust prevention and cleaning. The pH value of cutting fluid is generally between 8-10. If the pH value is too high, it will irritate human skin, cause skin allergies of the operator, and reduce the lubrication performance of the cutting fluid; if the pH value is too low, it is easy to breed bacteria, causing the cutting fluid to deteriorate and stink, and also affecting the lubrication and rust prevention properties of the cutting fluid. Therefore, the change of the pH value of the cutting fluid during the cutting process has a great impact on the service life of the cutting fluid and the quality of the processed workpiece.

[0003] However, the pH value of cutting fluid often decreases during use. This is mainly because: first, the cutting fluid is often in a high temperature and high humidity environment during use. This environment will not only accelerate the chemical reaction of the components in the cutting fluid and lower the pH value, but also speed up the reproduction of microorganisms. Microorganisms will consume alkaline components and lower the pH value; second, impurities such as metal chips will be produced in the metal cutting process. These impurities may react with the components in the cutting fluid and lower the pH value of the cutting fluid; third, water hardness and equipment operation factors will also lower the pH value of the cutting fluid.

[0004] A decrease in the pH value of the cutting fluid will further aggravate the growth of microorganisms, causing the cutting fluid to deteriorate and stink, shortening the service life of the cutting fluid and reducing the lubricating properties of the cutting fluid. Moreover, a decrease in the pH value will also accelerate the corrosion rate of the processing equipment, causing the workpiece and cutting tools to rust, reducing the service life of the processed workpiece and production efficiency.

[0005] In order to reduce the impact of the reduced pH value of the cutting fluid on the cutting process, the most common method is to regularly test and promptly add pH regulators to keep the pH value of the cutting fluid within the appropriate range. However, although this approach can alleviate the problem of reduced pH to a certain extent, it still has disadvantages such as complex operation, high cost, and unstable effect. Therefore, it is of great practical significance to develop a cutting fluid that can prevent the cutting fluid from deteriorating or reducing its performance at a low pH value, and will not have a significant impact on the workpiece and processing equipment. Summary of the Invention

[0006] In order to ensure that the cutting fluid maintains good lubrication, rust prevention, antibacterial and other properties when the pH value is reduced, the present application provides a cutting fluid for metal processing and a preparation method thereof.

[0007] A cutting fluid for metalworking, comprising the following components in parts by weight: 280-600 parts of water, 10-16 parts of a modified surfactant, 10-24 parts of a hydrogel, 2-5 parts of a rust inhibitor, 2-5 parts of an antibacterial agent, and 4-10 parts of a pH regulator; the hydrogel is at least one of carboxymethyl chitosan and polyethyleneimine; and a method for preparing the modified surfactant comprises the following steps:

[0008] S1: reacting the polyether with 4-toluenesulfonyl chloride under nitrogen protection to obtain an intermediate;

[0009] S2: react the intermediate with aldehyde under nitrogen protection to obtain the product.

[0010] In the above technical solution, the modified surfactant is an aldehyde-terminated polyethylene oxide-polypropylene oxide-polyethylene oxide triblock polymer, and the hydrogel contains amino groups. The aldehyde groups of the modified surfactant react with the amino groups in the hydrogel to form imine bonds, causing the hydrogel to cross-link to form a cross-linked hydrogel. The network structure of the cross-linked hydrogel encapsulates the rust inhibitor, antibacterial agent and pH adjuster, thereby slowly releasing the rust inhibitor, antibacterial agent and pH adjuster.

[0011] The cross-linked hydrogel can absorb and store a large amount of heat, effectively reducing the cutting temperature and reducing the deformation or damage of the workpiece and tool due to overheating; moreover, under alkaline conditions, the imine bond is relatively stable, the rust inhibitor and antibacterial agent are embedded in the cross-linked hydrogel, and the release rate is very slow. When the cutting fluid is in use, the pH continues to decrease, the amino groups in the cutting fluid are protonated, and the intramolecular electrostatic repulsion and enhanced hydrophilicity cause the gel to expand rapidly. At the same time, the imine bond will also decompose, causing the cross-linking points in the hydrogel to be destroyed, thereby quickly releasing the rust inhibitor, antibacterial agent and pH adjuster. Rust-saving agents and rust inhibitors can form a protective film on the metal surface, isolating the metal from corrosive media such as moisture, oxygen, acid and alkali substances in the cutting fluid, thereby effectively preventing metal corrosion. Antibacterial agents are beneficial to preventing bacterial growth and improving the antibacterial properties of the cutting fluid. pH regulators can promote the reformation of broken imine bonds, thereby not only effectively reducing the rate of decrease of the pH value of the cutting fluid, improving the service life of the cutting fluid and its lubrication, rust prevention and other properties, but also reducing the amount and frequency of addition of rust inhibitors, antibacterial agents and pH regulators, thereby improving production efficiency.

[0012] Because the aldehyde groups at both ends of the modified surfactant form an imine bond with the amino group in the hydrogel, and the hydrophobic part in the middle forms a cavity, the modified surfactant can form nanomicelles in an aqueous solution. This nanomicelle structure can not only be used to load rust inhibitors and antibacterial agents, thereby improving the compatibility of antibacterial agents and rust inhibitors in cutting fluids, but also form a nanolubricating film at the cutting interface, thereby reducing the friction and wear between the tool and the workpiece, and improving the lubrication performance of the cutting fluid. In addition, the nanomicelles can penetrate into the tiny gaps on the surface of the workpiece, thereby reducing the direct contact area between the tool and the workpiece, further reducing the wear rate, and improving the lubrication performance of the cutting fluid. In addition, the nanomicelles have a high thermal conductivity and can effectively conduct the heat generated during the cutting process, thereby reducing the cutting temperature, preventing the workpiece and tool from deforming, and affecting the processing quality.

[0013] Preferably, it includes at least one of the following technical features:

[0014] A1) the rust inhibitor is dodecanedioic acid or sebacic acid;

[0015] A2) The pH adjuster is one or more of triethanolamine, diethanolamine, monoethanolamine and isopropanolamine.

[0016] Preferably, the pH value of the metalworking cutting fluid is 8-10.

[0017] In the above technical solution, the dicarboxylic acid in the rust inhibitor reacts with the alcoholamine in the pH adjuster to improve the rust-proofing properties of the cutting fluid. The pH adjuster adjusts the pH of the metalworking cutting fluid to between 8 and 10, more preferably between 8 and 9. A high pH value can irritate human skin, causing allergies and reduced lubricity. A low pH value can easily breed bacteria, causing the cutting fluid to deteriorate and become smelly. Therefore, a higher pH value is not necessarily better for metalworking cutting fluids during initial use.

[0018] Preferably, it includes at least one of the following technical features:

[0019] B1) In step S1, the polyether is one or more of polyether P-123, polyether F-108 and polyether F-68;

[0020] B2) In step S1, the mass ratio of the polyether to 4-toluenesulfonyl chloride is 10:(0.3-0.5).

[0021] In the above technical solution, the polyether is a triblock nonionic surfactant, which does not ionize into ions in water, and is therefore less affected by water quality and electrolytes and has higher stability. Moreover, the polyether has longer hydrophilic and hydrophobic segments, which make it easier to adsorb on the metal surface to form a denser protective film, thereby effectively preventing the metal from being oxidized or corroded. In addition, the longer molecular chain segments can be dynamically adjusted during the cutting process to adapt to different cutting conditions, and the longer hydrophobic segments can form a stronger lubricating film between the tool and the workpiece, thereby significantly reducing the friction coefficient, reducing tool wear, and reducing the surface roughness of the workpiece. In addition, the polyether has stronger penetration and dispersion capabilities, and the hydrophilic and hydrophobic segments in its molecular structure work synergistically to make dirt easier to emulsify and disperse in the cutting fluid, making it perform better in cleaning and decontamination, and can more effectively clean metal debris, sand particles and other dirt from the workpiece surface.

[0022] Preferably, it includes at least one of the following technical features:

[0023] C1) In step S2, the aldehyde is one or more of acetaldehyde, benzaldehyde, cinnamaldehyde, salicylaldehyde and citral;

[0024] C2) In step S2, the mass ratio of the intermediate to the aldehyde is 10:(0.5-2).

[0025] In the above technical solution, the role of aldehyde is to react with the intermediate and end-cap with aldehyde groups. The aldehyde groups can react with the amino groups in the hydrogel to form imine bond cross-linking points, thereby increasing the cross-linking density of the hydrogel.

[0026] Preferably, the hydrogel is modified by a method comprising the following steps:

[0027] The hydrogel is dissolved in water, and a graphene oxide aqueous solution is added to react, followed by freeze drying and grinding.

[0028] Using the above technical solution, the epoxy groups on the surface of graphene oxide react with the amino groups in the hydrogel to graft the hydrogel onto the surface of graphene oxide. First, after the graphene oxide is grafted onto the hydrogel, the graphene oxide can be better dispersed and more stable, providing better lubrication during the cutting process, reducing friction and wear between the tool and the workpiece, thereby reducing the surface roughness of the workpiece and improving the quality of the workpiece. Second, the graphene oxide flakes have good thermal conductivity. During the cutting process, the graphene oxide can quickly absorb and carry away the heat generated in the cutting area, effectively reducing the cutting temperature and reducing thermal deformation and wear caused by overheating, thereby improving the cooling performance of the cutting fluid, extending the service life of the tool, and improving processing accuracy and efficiency. In addition, the graphene oxide surface has a large number of polar groups and a large specific surface area, which makes it easy to adsorb on the surface of the tool or workpiece, effectively reducing the contact of corrosive media with them, thereby effectively improving the rust prevention and corrosion resistance of the cutting fluid. Finally, the graphene oxide can increase the strength of the hydrogel, and the mutual slip between the flakes can also reduce stress concentration, thereby increasing the service life of the cutting fluid and the load it can withstand.

[0029] Preferably, the mass ratio of the hydrogel to graphene oxide is 100:(4-16).

[0030] Further preferably, the graphene oxide is modified by a method comprising the following steps:

[0031] The graphene oxide is ultrasonically dispersed in a solvent, unsaturated acid triethanolamine is added, nitrogen is passed through, an initiator is added to react, the reaction is cooled after the reaction, and methanol is used for precipitation. After the precipitate is dissolved, it is centrifuged and vacuum dried.

[0032] By adopting the above technical solution, the double bonds in the unsaturated acid triethanolamine react with the double bonds on the surface of the graphene oxide to graft the unsaturated acid triethanolamine polymer chains onto the surface of the graphene oxide. The grafting density is high and the grafting uniformity is good. The grafted unsaturated acid triethanolamine has a long alkyl chain and can be regarded as a polymer brush. It can form a dense lubricating film during the cutting process, avoid direct contact between the tool and the workpiece, thereby reducing friction and wear between the tool and the workpiece, and improving the lubrication performance of the cutting fluid. In addition, the hydrophobic and dense long chains can prevent microorganisms and corrosive media from approaching the workpiece or the tool surface, thereby improving the rust prevention, corrosion resistance and antibacterial properties of the cutting fluid and slowing down the deterioration of the cutting fluid.

[0033] Preferably, it includes at least one of the following technical features:

[0034] D1) the unsaturated acid triethanolamine is one or more of oleic acid triethanolamine, linoleic acid triethanolamine and linolenic acid triethanolamine;

[0035] D2) The mass ratio of the graphene oxide to the unsaturated acid triethanolamine is 1:(20-50).

[0036] In the above technical solution, the longer alkyl chains in the unsaturated triethanolamine are free of branches and are hydrophobic, reducing friction. The more electronegative nitrogen atoms can adsorb more molecules, enhancing the strength of the lubricating film. Furthermore, in some specific embodiments, the mass ratio of graphene oxide to unsaturated triethanolamine is 1:20, 1:25, 1:30, 1:40, or 1:50. A mass ratio of 1:40 achieves the best experimental results.

[0037] A method for preparing a cutting fluid for metal processing comprises the following steps:

[0038] Heat the rust inhibitor and pH regulator to react, add water and hydrogel after cooling, stir evenly, add modified surfactant and antibacterial agent, mix evenly at 2-6°C.

[0039] Using the above technical solution, on the one hand, the hydrogel reacts with the modified surfactant to form a cross-linked hydrogel with imine bonds as cross-linking points, embedding the rust inhibitor, antibacterial agent, etc. in the cross-linked network structure, thereby realizing the slow release of the rust inhibitor, antibacterial agent, etc.; on the other hand, the imine bond has a pH response characteristic. When the pH value of the cutting fluid is low, the imine bond cross-linking point is destroyed, and the rust inhibitor, antibacterial agent, etc. in the cross-linked hydrogel network is released, inhibiting the corrosion of the metal surface and the growth of microorganisms such as bacteria, slowing down the rate of decrease of the pH value of the cutting fluid, and improving the rust prevention and antibacterial properties of the cutting fluid, thereby increasing the service life of the cutting fluid.

[0040] The above technical solution of the present application has at least the following beneficial effects:

[0041] 1. This application forms a cross-linked hydrogel with imine bonds as cross-linking points between the modified surfactant and the hydrogel to encapsulate rust inhibitors, antibacterial agents, and pH regulators. When the pH of the cutting fluid is low, the cross-linking points are destroyed, thereby releasing the rust inhibitors, antibacterial agents, and pH regulators, reducing the pH reduction rate of the cutting fluid, reducing the amount and frequency of addition of the pH regulator, and improving the rust prevention and antibacterial properties and service life of the cutting fluid.

[0042] 2. This application improves the lubrication, cooling, rust prevention, and corrosion resistance of cutting fluids by introducing graphene oxide into hydrogels;

[0043] 3. This application further improves the lubrication, rust prevention, and corrosion resistance of the cutting fluid by grafting unsaturated acid triethanolamine onto graphene oxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 1 is a curve showing the degradation rate of the cross-linked hydrogel in the metalworking cutting fluid of Example 1 versus the storage time;

[0045] Figure 2 This is the microscopic morphology of the hydrogel in Example 2 and Example 3. DETAILED DESCRIPTION

[0046] The present application is further described in detail below with reference to the embodiments.

[0047] Unless otherwise specified, the raw materials used in the examples and comparative examples of the present application are all commercially available.

[0048] Example 1

[0049] The metalworking cutting fluid of this embodiment is composed of the following components in parts by weight: 280 parts of water, 10 parts of modified surfactant, 10 parts of hydrogel, 2 parts of dodecanedioic acid, 2 parts of hydroxyethyl hexahydro-s-triazine, and 4 parts of triethanolamine;

[0050] The preparation method of the modified surfactant in this embodiment comprises the following steps:

[0051] S1: Weigh 10 g of polyether F-68, add 120 mL of dichloromethane, place in an ice-salt bath and stir evenly, add 1.2 g of triethylamine, and pass nitrogen protection, slowly add 20 mL of dichloromethane solution containing 0.3 g of phenylmethanesulfonyl chloride, and react at room temperature for 24 h. After the reaction is completed, add 200 mL of deionized water, extract with dichloromethane, and wash the organic phase with saturated sodium chloride solution. Concentrate the organic phase by rotary evaporation, add the organic phase to ice ether for precipitation, filter, and vacuum dry to obtain an intermediate;

[0052] S2: Weigh 10 g of the above intermediate, add 0.5 g of acetaldehyde, 1 g of sodium carbonate, and 100 mL of N,N-dimethylformamide, and react at 80°C for 12 h with stirring under nitrogen protection. Add 200 mL of deionized water, extract with dichloromethane, and wash the organic phase with saturated sodium chloride solution. Concentrate the organic phase by rotary evaporation, precipitate the organic phase with glacial ether, filter, and dry in vacuo;

[0053] In this embodiment, the hydrogel is carboxymethyl chitosan;

[0054] The preparation method of the metalworking cutting fluid of this embodiment comprises the following steps:

[0055] Weigh 2 g of dodecanedioic acid and 4 g of triethanolamine, react at 90°C for 30 min, cool, add 10 g of carboxymethyl chitosan and 280 g of water, stir at room temperature for 6 h, add 10 g of modified surfactant and 2 g of hydroxyethyl hexahydro-s-triazine, and mix quickly at 2°C until uniform.

[0056] Example 2

[0057] The metalworking cutting fluid of this embodiment is composed of the following components by weight: 600 parts of water, 16 parts of a modified surfactant, 24 parts of a hydrogel, 5 parts of sebacic acid, 5 parts of hydroxyethyl hexahydro-s-triazine, and 10 parts of diethanolamine; the hydrogel is polyethyleneimine;

[0058] The preparation method of the modified surfactant in this embodiment comprises the following steps:

[0059] S1: Weigh 10 g of polyether F-108, add 120 mL of dichloromethane, place in an ice-salt bath and stir evenly, add 1.2 g of triethylamine, and pass nitrogen protection, slowly add 20 mL of dichloromethane solution containing 0.5 g of phenylmethanesulfonyl chloride, and react at room temperature for 12 h. After the reaction, add 150 mL of deionized water, extract with dichloromethane, and wash the organic phase with saturated sodium chloride solution. Concentrate the organic phase by rotary evaporation, add the organic phase to ice ether for precipitation, filter, and vacuum dry to obtain the intermediate;

[0060] S2: Weigh 10 g of the above intermediate, add 1 g of benzaldehyde, 1.5 g of sodium carbonate, and 100 mL of N,N-dimethylformamide, and react at 100°C for 6 h with stirring under nitrogen protection. Add 150 mL of deionized water, extract with dichloromethane, and wash the organic phase with saturated sodium chloride solution. Concentrate the organic phase by rotary evaporation, precipitate the organic phase with glacial ether, filter, and dry in vacuo;

[0061] The method for preparing the hydrogel in this embodiment comprises the following steps:

[0062] Weigh 5 g of polyethyleneimine, dissolve it in 100 g of water, mix well, add 10 g of a 2% by mass graphene oxide aqueous solution, stir well, react at 60 ° C for 8 h, freeze at -20 ° C for 24 h, freeze-dry, and grind.

[0063] The preparation method of the metalworking cutting fluid of this embodiment comprises the following steps:

[0064] Weigh 5g of sebacic acid and 10g of diethanolamine, react at 90°C for 60min, cool, add 20g of polyethyleneimine and 650g of water, stir at room temperature for 6h, add 20g of modified surfactant and 5g of hydroxyethylhexahydro-s-triazine, and mix quickly at 6°C until uniform.

[0065] Example 3

[0066] The metalworking cutting fluid of this embodiment is composed of the following components in parts by weight: 440 parts of water, 15 parts of modified surfactant, 15 parts of hydrogel, 4 parts of sebacic acid, 3 parts of hydroxyethyl hexahydro-s-triazine, and 7 parts of isopropanolamine;

[0067] The preparation method of the modified surfactant comprises the following steps:

[0068] S1: Weigh 10 g of polyether P-123, add 120 mL of dichloromethane, place in an ice-salt bath and stir evenly, add 1.2 g of triethylamine, and pass nitrogen protection, slowly add 20 mL of dichloromethane solution containing 0.4 g of phenylmethanesulfonyl chloride, and react at room temperature for 10 h. After the reaction, add 150 mL of deionized water, extract with dichloromethane, and wash the organic phase with saturated sodium chloride solution. Concentrate the organic phase by rotary evaporation, add the organic phase to ice ether for precipitation, filter, and vacuum dry to obtain the intermediate;

[0069] S2: Weigh 10 g of the above intermediate, add 2 g of salicylaldehyde, 1.5 g of sodium carbonate, and 100 mL of N,N-dimethylformamide, and react at 95°C for 8 h with stirring under nitrogen protection. Add 150 mL of deionized water, extract with dichloromethane, and wash the organic phase with saturated sodium chloride solution. Concentrate the organic phase by rotary evaporation, precipitate the organic phase with glacial ether, filter, and dry in vacuo;

[0070] The method for preparing the hydrogel in this embodiment comprises the following steps:

[0071] Weigh 2g of carboxymethyl chitosan and 3g of polyethyleneimine, dissolve them in 100g of water, mix well, add 40g of 2% graphene oxide aqueous solution, stir well, react at 80°C for 4h, freeze at -20°C for 24h, freeze-dry and grind;

[0072] In this embodiment, graphene oxide is modified using a method comprising the following steps:

[0073] Weigh 1 g of graphene oxide and 200 mL of N,N-dimethylformamide, ultrasonically disperse for 1 h, add 40 g of triethanolamine oleate while stirring, introduce nitrogen for 20 min, add 0.5 g of azobisisobutyronitrile, react at 65°C for 24 h, cool, precipitate with methanol, dissolve the precipitate with N,N-dimethylformamide, centrifuge, and vacuum dry.

[0074] The preparation method of the metalworking cutting fluid of this embodiment comprises the following steps:

[0075] Weigh 4g of sebacic acid and 7g of isopropanolamine, react at 90°C for 45min, cool, add 15g of hydrogel and 440g of water, stir at room temperature for 6h, add 15g of modified surfactant and 3g of hydroxyethylhexahydro-s-triazine, and mix quickly at 4°C until uniform.

[0076] Comparative Example 1

[0077] The metalworking cutting fluid of this comparative example is composed of the following components in parts by weight: 280 parts of water, 10 parts of polyether F-68, 10 parts of hydrogel, 2 parts of dodecanedioic acid, 2 parts of hydroxyethyl hexahydro-s-triazine, and 4 parts of triethanolamine;

[0078] In this comparative example, the hydrogel is carboxymethyl chitosan;

[0079] The preparation method of the metalworking cutting fluid of this comparative example comprises the following steps:

[0080] Weigh 2g of dodecanedioic acid and 4g of triethanolamine, react at 90°C for 30min, cool, add 10g of carboxymethyl chitosan and 280g of water, stir at room temperature for 6h, add 10g of polyether F-68 and 2g of hydroxyethyl hexahydro-s-triazine, mix well, and it is done.

[0081] Performance testing

[0082] 1. Degradation test of cross-linked hydrogel

[0083] This experiment characterizes the degree of destruction of the imine bond by the degradation rate of the cross-linked hydrogel formed in the metalworking cutting fluid of Example 1 under different pH conditions. The greater the degradation rate, the more the imine bond is destroyed. Weigh 10 mL of the metalworking cutting fluid of Example 1 and put it into 50 mL of phosphate buffer solution with pH = 8 and phosphate buffer solution with pH = 6.8 respectively. Keep the temperature at 25°C. After 0 days, 1 day, 3 days, 5 days, 7 days, 15 days and 30 days, remove the solution and wipe off the water. Weigh and calculate the degradation rate of the cross-linked hydrogel in the cutting fluid = W0-W t / W t ×100%, where W0 is the mass of the cutting fluid after wiping off the water when no phosphate buffer solution is added; W t is the mass of the cutting fluid after being dried in phosphate buffer on the tth day. The degradation rate of the cross-linked hydrogel in the cutting fluid changes with the placement time as shown in Figure 1 shown.

[0084] 2. Rust resistance, corrosion resistance and lubricity test

[0085] Rust resistance and corrosion resistance were tested in accordance with the standard GB / T6144-2010 “Synthetic Cutting Fluids.” The lubricity was evaluated by measuring the wear spot area and weight loss of the test column using a Reichert friction and wear tester. The results are shown in Table 1.

[0086] Table 1 Properties of the metalworking cutting fluids of Examples 1-3 and Comparative Example 1

[0087]

[0088] 3. Scanning electron microscopy observation

[0089] The micromorphology of the hydrogels prepared in Example 2 and Example 3 was observed by scanning electron microscopy. Figure 2 shown.

[0090] Result Analysis

[0091] from Figure 1 It can be seen that as the pH of the cutting fluid for metal processing decreases, the degradation rate of the cross-linked hydrogel increases significantly. This is because when the pH is low, the imine bond breaks, the cross-linking points of the cross-linked hydrogel are destroyed, and the cross-linked hydrogel degrades.

[0092] Comparing the data of the examples and the comparative examples in Table 1, it can be seen that the metal processing cutting fluid of the examples has better anti-rust performance, anti-corrosion performance and lubrication performance. This may be because during the use of the cutting fluid, the cross-linked hydrogel can release rust inhibitors, antibacterial agents, etc. when the pH is low, which can effectively reduce rust and corrosion of tools, workpieces, etc. and deterioration of the cutting fluid; Comparing the data of Examples 1-3 in Table 1, it can be seen that when graphene oxide is added to the hydrogel, the wear loss and wear spot area of the cutting fluid are smaller, indicating that the wear resistance and lubrication performance of the cutting fluid are better; when the unsaturated acid triethanolamine is grafted onto the surface of the graphene oxide, the wear resistance and lubrication performance are further improved.

[0093] from Figure 2 It can be seen that the hydrogel in Example 2 successfully introduced the graphene oxide sheet, and the hydrogel in Example 3 successfully grafted the long-chain polymer. The introduction of graphene oxide and long-chain polymer is beneficial to improving the lubrication performance of the cutting fluid.

[0094] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A cutting fluid for metal processing, characterized in that: The invention comprises the following components in parts by weight: 280-600 parts of water, 10-16 parts of a modified surfactant, 10-24 parts of a hydrogel, 2-5 parts of a rust inhibitor, 2-5 parts of an antibacterial agent, and 4-10 parts of a pH regulator; the hydrogel is at least one of carboxymethyl chitosan and polyethyleneimine; and the preparation method of the modified surfactant comprises the following steps: S1: reacting a polyether with 4-toluenesulfonyl chloride under nitrogen protection to obtain an intermediate; the polyether is one or more of polyether P-123, polyether F-108, and polyether F-68; and the mass ratio of the polyether to 4-toluenesulfonyl chloride is 10:(0.3-0.5); S2: react the intermediate with aldehyde under nitrogen protection to obtain the product.

2. The metalworking cutting fluid according to claim 1, characterized in that: Include at least one of the following technical features: A1) the rust inhibitor is dodecanedioic acid or sebacic acid; A2) The pH adjuster is one or more of triethanolamine, diethanolamine, monoethanolamine and isopropanolamine.

3. The metalworking cutting fluid according to claim 1, wherein: The pH value of the metalworking cutting fluid is 8-10.

4. The metalworking cutting fluid according to claim 1, wherein: Include at least one of the following technical features: C1) In step S2, the aldehyde is one or more of acetaldehyde, benzaldehyde, cinnamaldehyde, salicylaldehyde and citral; C2) In step S2, the mass ratio of the intermediate to the aldehyde is 10:(0.5-2).

5. The metalworking cutting fluid according to claim 1, characterized in that: The hydrogel is modified by a method comprising the following steps: The hydrogel is dissolved in water, and a graphene oxide aqueous solution is added to react, followed by freeze drying and grinding.

6. The metalworking cutting fluid according to claim 5, characterized in that: The mass ratio of the hydrogel to graphene oxide is 100:(4-16).

7. The metalworking cutting fluid according to claim 5, characterized in that: The graphene oxide is modified by a method comprising the following steps: The graphene oxide is ultrasonically dispersed in a solvent, unsaturated acid triethanolamine is added, nitrogen is passed through, an initiator is added to react, the reaction is cooled after the reaction, and methanol is used for precipitation. After the precipitate is dissolved, it is centrifuged and vacuum dried.

8. The metalworking cutting fluid according to claim 7, characterized in that: Include at least one of the following technical features: D1) the unsaturated acid triethanolamine is one or more of oleic acid triethanolamine, linoleic acid triethanolamine and linolenic acid triethanolamine; D2) The mass ratio of the graphene oxide to the unsaturated acid triethanolamine is 1:(20-50).

9. A method for preparing a metalworking cutting fluid according to any one of claims 1 to 8, characterized in that: The steps include: Heat the rust inhibitor and pH regulator to react, add water and hydrogel after cooling, stir evenly, add modified surfactant and antibacterial agent, mix evenly at 2-6°C.

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