Cutting fluid for metal processing and preparation method thereof

Abstract

The invention relates to the technical field of cutting fluid, in particular to cutting fluid for metal processing and a preparation method of the cutting fluid. The cutting fluid for metal processing comprises water, a modified surfactant, hydrogel, an anti-rust agent, an antibacterial agent and a pH regulator, and during preparation, the anti-rust agent and the pH regulator react, and then the hydrogel, the modified surfactant and the antibacterial agent are added to form cross-linked hydrogel; the modified surfactant can form nano-micelles in an aqueous solution, is terminated by aldehyde groups and reacts with hydrogel to form imine bond cross-linking points, so that the anti-rust performance, corrosion resistance, antibacterial performance and the like of the cutting fluid at a low pH value are improved, deterioration of the cutting fluid is effectively reduced, and the service life of the cutting fluid is prolonged; in addition, lamellar graphene oxide is introduced into the hydrogel and is grafted with a polymer, so that the cooling performance, the anti-rust performance, the corrosion resistance and the lubricating performance of the cutting fluid are further improved.

Description

Technical Field

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

[0002] During the metal cutting process, as an important auxiliary material, cutting fluid has multiple functions such as cooling, lubricating, rust-proofing, and cleaning. The pH value of cutting fluid generally ranges between 8 - 10. If the pH value is too high, it will irritate human skin, causing skin allergies to operators, and also reducing the lubricating performance of the cutting fluid; if the pH value is small, it is easy to breed bacteria, causing the cutting fluid to deteriorate and stink, and also affecting the lubricating performance, rust-proofing performance, etc. of the cutting fluid. Therefore, the change of the pH value of cutting fluid during the cutting process has a great impact on both the service life of the cutting fluid and the quality of the machined workpiece.

[0003] However, the phenomenon of the pH value of cutting fluid often decreasing during use is mainly due to: 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, causing the pH value to decrease, but also accelerate the reproduction speed of microorganisms. Microorganisms will consume alkaline components, causing the pH value to decrease; Second, during the metal cutting process, impurities such as metal chips will be generated, and these impurities may react with the components in the cutting fluid, causing the pH value of the cutting fluid to decrease; Third, water hardness and equipment operation factors will also cause the pH value of the cutting fluid to decrease.

[0004] The decrease in the pH value of the cutting fluid will further exacerbate the growth of microorganisms, causing the cutting fluid to deteriorate and stink, shortening the service life of the cutting fluid, reducing the lubricating performance of the cutting fluid. Moreover, after the pH value decreases, it will also accelerate the corrosion speed of the processing equipment, causing the workpiece and the tool to rust, and reducing the service life and production efficiency of the machined workpiece.

[0005] In order to reduce the impact of the decrease in the pH value of the cutting fluid on the cutting process, the most common method is to regularly detect and timely supplement the pH value regulator to keep the pH value of the cutting fluid within a suitable range. However, although this approach can alleviate the problem of pH decrease to a certain extent, there are still deficiencies such as complex operation, high cost, and unstable effect. Therefore, it is of great practical significance to develop a cutting fluid that will not cause the cutting fluid to deteriorate or its performance to decrease when the pH value is low, and will not have a great impact on the workpiece and the processing equipment. Summary of the Invention

[0006] In order to enable the cutting fluid to still maintain good lubricating, rust-proofing, antibacterial and other properties when the pH value decreases, the present application provides a cutting fluid for metal processing and a preparation method thereof.

[0007] A cutting fluid for metal processing, comprising components in the following parts by weight: water 280 - 600 parts, modified surfactant 10 - 16 parts, hydrogel 10 - 24 parts, rust inhibitor 2 - 5 parts, antibacterial agent 2 - 5 parts, pH regulator 4 - 10 parts; the hydrogel is at least one of carboxymethyl chitosan and polyethyleneimine; the preparation method of the modified surfactant includes the following steps: S1: React polyether with 4-toluenesulfonyl chloride under nitrogen protection to obtain an intermediate; S2: React the intermediate with aldehyde under nitrogen protection to obtain the product.

[0008] In the above technical solution, the modified surfactant is an aldehyde-terminated poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock polymer, the hydrogel contains amino groups, and the aldehyde groups of the modified surfactant react with the amino groups in the hydrogel to form imine bonds, causing the hydrogel to crosslink to form a crosslinked hydrogel. The network structure of the crosslinked hydrogel entraps the rust inhibitor, antibacterial agent, and pH regulator, so that the rust inhibitor, antibacterial agent, and pH regulator are slowly released.

[0009] This crosslinked 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, and the rust inhibitor and antibacterial agent are entrapped in the crosslinked hydrogel and released very slowly. When the cutting fluid is in use and the pH continuously decreases, the amino groups in the cutting fluid are protonated, and the intramolecular electrostatic repulsion and enhanced hydrophilicity cause the gel to rapidly swell. At the same time, the imine bond also decomposes, destroying the crosslinking points in the hydrogel, and then rapidly releasing the rust inhibitor, antibacterial agent, and pH regulator. The rust inhibitor can form a protective film on the metal surface, isolating the metal from corrosive media such as moisture, oxygen, acid-base substances, etc. in the cutting fluid, thus effectively preventing metal corrosion. The antibacterial agent is beneficial to preventing bacterial growth and improving the antibacterial performance of the cutting fluid. The pH regulator can promote the reformation of the broken imine bond, so that not only can the reduction rate of the pH value of the cutting fluid be effectively reduced, improving the service life and lubrication, rust prevention and other properties of the cutting fluid, but also the addition amount and addition frequency of the rust inhibitor, antibacterial agent, and pH regulator can be reduced, improving production efficiency.

[0010] Due to the formation of imine bonds between the aldehyde groups at both ends of the modified surfactant and the amino groups in the hydrogel, and the formation of cavities in the middle hydrophobic part, the modified surfactant can form nano - micelles in aqueous solution. This nano - micelle structure can not only be used to load rust inhibitors and antibacterial agents, improving the compatibility of antibacterial agents and rust inhibitors in cutting fluids, but also form a nano - lubricating film at the cutting interface, reducing the friction and wear between the tool and the workpiece, and improving the lubrication performance of the cutting fluid. In addition, the nano - micelles can penetrate into the micro - gaps on the surface of the workpiece, 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. Moreover, the nano - micelles have a high thermal conductivity coefficient, which can effectively conduct the heat generated during the cutting process, thereby reducing the cutting temperature and preventing the deformation of the workpiece and the tool, which may affect the machining quality.

[0011] Preferably, it includes at least one of the following technical features: A1) The rust inhibitor is dodecanedioic acid or sebacic acid; A2) The pH regulator is one or more of triethanolamine, diethanolamine, monoethanolamine, and isopropanolamine.

[0012] Preferably, the pH value of the cutting fluid for metal processing is 8 - 10.

[0013] In the above - mentioned technical solution, the dibasic carboxylic acid in the rust inhibitor reacts with the alkanolamine in the pH regulator, which can improve the rust - proof performance of the cutting fluid. The pH regulator adjusts the pH value of the cutting fluid for metal processing between 8 - 10, more preferably between 8 - 9. If the pH value is too high, it will irritate the human skin, causing skin allergies to the operator, and also reducing the lubrication performance of the cutting fluid. If the pH value is too small, bacteria are likely to grow, causing the cutting fluid to deteriorate and emit an odor. Therefore, the pH value of the cutting fluid for metal processing at the initial use is not the higher the better.

[0014] Preferably, it includes at least one of the following technical features: B1) In step S1, the polyether is one or more of polyether P - 123, polyether F - 108, and polyether F - 68; B2) In step S1, the mass ratio of the polyether to 4 - toluenesulfonyl chloride is 10:(0.3 - 0.5).

[0015] In the above technical solution, the polyether is a triblock nonionic surfactant and does not ionize ions in water. Therefore, it is less affected by water quality and electrolytes and has high stability. Moreover, the polyether has a long hydrophilic segment and a long hydrophobic segment, which makes it easier to adsorb on the metal surface to form a denser protective film, thus effectively preventing the metal from being oxidized or corroded. In addition, the long molecular chain segment can be dynamically adjusted during the cutting process to adapt to different cutting conditions. The long hydrophobic chain segment can form a more solid lubricating film between the tool and the workpiece, thus significantly reducing the friction coefficient, reducing tool wear, and lowering the surface roughness of the workpiece. Furthermore, the polyether has stronger penetration and dispersion capabilities. The hydrophilic and hydrophobic chain segments in its molecular structure work together to make dirt more easily emulsified and dispersed in the cutting fluid, showing better cleaning and decontamination effects, and being able to more effectively wash off dirt such as metal chips and sand grains from the workpiece surface.

[0016] Preferably, it includes 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).

[0017] In the above technical solution, the role of the aldehyde is to react with the intermediate and cap with an aldehyde group. The aldehyde group can react with the amino group in the hydrogel to form an imine bond crosslinking point, improving the crosslinking density of the hydrogel.

[0018] Preferably, the hydrogel is modified by a method including the following steps: Dissolve the hydrogel in water, add an aqueous solution of graphene oxide for reaction, and then perform freeze-drying and grinding.

[0019] With the above technical solution, the epoxy groups on the surface of graphene oxide react with the amino groups in the hydrogel, grafting the hydrogel onto the surface of graphene oxide. First, after graphene oxide is grafted with the hydrogel, graphene oxide can be better dispersed and has higher stability, providing a better lubricating effect during the cutting process, reducing the friction and wear between the tool and the workpiece, thereby reducing the surface roughness of the workpiece and improving the workpiece quality. Second, the sheet-like graphene oxide has good thermal conductivity. During the cutting process, graphene oxide can quickly absorb and carry away the heat generated in the cutting area, effectively reducing the cutting temperature, reducing the 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 the machining accuracy and efficiency. In addition, the surface of graphene oxide has many polar groups and a large specific surface area, which is easy to adsorb on the surface of the tool or workpiece, effectively reducing the contact between the corrosive medium and it, thereby effectively improving the rust prevention and corrosion resistance of the cutting fluid. Finally, graphene oxide can improve the strength of the hydrogel, and the mutual slip between the sheets can also reduce stress concentration, thereby improving the service life and load-bearing capacity of the cutting fluid.

[0020] Preferably, the mass ratio of the hydrogel to graphene oxide is 100:(4 - 16).

[0021] More preferably, the graphene oxide is modified by a method including the following steps: Ultrasonically disperse graphene oxide in a solvent, add triethanolamine unsaturated acid, protect with nitrogen, add an initiator to react, cool after the reaction, precipitate with methanol, dissolve the precipitate, and then perform centrifugal separation and vacuum drying.

[0022] With the above technical solution, the double bond in triethanolamine unsaturated acid undergoes an addition reaction with the double bond on the surface of graphene oxide, grafting the triethanolamine unsaturated acid polymer chain onto the surface of graphene oxide. The grafting density is high, the grafting uniformity is good, and the grafted triethanolamine unsaturated acid has a long alkyl chain, which can be regarded as a polymer brush, and can form a dense lubricating film during the cutting process, avoiding direct contact between the tool and the workpiece, thereby reducing the friction and wear between the tool and the workpiece and improving the lubricating performance of the cutting fluid. In addition, the hydrophobic and dense long chains can prevent microorganisms and corrosive media from approaching the surface of the workpiece or the tool, thereby improving the rust prevention performance, corrosion resistance and antibacterial performance of the cutting fluid and slowing down the deterioration of the cutting fluid.

[0023] Preferably, it includes at least one of the following technical features: D1) The triethanolamine unsaturated acid is one or more of triethanolamine oleate, triethanolamine linoleate and triethanolamine linolenate; D2) The mass ratio of the graphene oxide to the triethanolamine unsaturated acid is 1:(20 - 50).

[0024] In the above technical solution, the long alkyl chain in triethanolamine unsaturated acid has no branches and is hydrophobic, which can reduce friction. The nitrogen atom with a relatively large electronegativity can adsorb more molecules and enhance the strength of the lubricating film. Additionally, in some specific embodiments, the mass ratio of graphene oxide to triethanolamine unsaturated acid is 1:20, 1:25, 1:30, 1:40, 1:50. Among them, when the mass ratio of graphene oxide to triethanolamine unsaturated acid is 1:40, the experimental effect is better.

[0025] A preparation method of a cutting fluid for metal processing includes the following steps: Heat and react the rust inhibitor and the pH regulator, add water and hydrogel after cooling, stir evenly, add the modified surfactant and the antibacterial agent, and mix evenly at 2 - 6 °C.

[0026] Adopting the above technical solution, on the one hand, the hydrogel reacts with the modified surfactant to form a crosslinked hydrogel with imine bonds as crosslinking points, embedding the rust inhibitor, antibacterial agent, etc. in the crosslinked network structure to achieve the slow release of the rust inhibitor, antibacterial agent, etc. On the second hand, the imine bond has pH-responsive characteristics. When the pH value of the cutting fluid is low, the imine bond crosslinking points are destroyed, and the rust inhibitor, antibacterial agent, etc. in the crosslinked hydrogel network are released, inhibiting the corrosion of the metal surface and the growth of bacteria and other microorganisms, slowing down the reduction rate of the pH value of the cutting fluid, and improving the rust prevention performance and antibacterial performance of the cutting fluid, thereby increasing the service life of the cutting fluid.

[0027] The above technical solution of the present application has at least the following beneficial effects: 1. In the present application, a crosslinked hydrogel with imine bonds as crosslinking points is formed between the modified surfactant and the hydrogel to embed the rust inhibitor, antibacterial agent, pH regulator, etc. When the pH of the cutting fluid is low, the crosslinking points are destroyed, realizing the release of the rust inhibitor, antibacterial agent, pH regulator, etc., reducing the reduction rate of the pH of the cutting fluid, reducing the addition amount and addition frequency of the pH regulator, and improving the rust prevention performance, antibacterial performance and service life of the cutting fluid, etc.; 2. In the present application, by introducing graphene oxide into the hydrogel, the lubricating performance, cooling performance, rust prevention performance, corrosion resistance performance, etc. of the cutting fluid are improved; 3. In the present application, by grafting triethanolamine unsaturated acid onto graphene oxide, the lubricating performance, rust prevention performance, corrosion resistance performance, etc. of the cutting fluid are further improved. Description of the Drawings

[0028] Figure 1 It is a curve showing the change of the degradation rate of the crosslinked hydrogel in the cutting fluid for metal processing in Example 1 with the storage time; Figure 2It is the microscopic morphology of the hydrogel in Example 2 and Example 3. Detailed implementation mode

[0029] The following further elaborates on this application in conjunction with examples.

[0030] The raw materials of the examples and comparative examples of this application are all ordinary commercially available except as otherwise specified.

[0031] Example 1 The cutting fluid for metal processing in this example 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; The preparation method of the modified surfactant in this example includes the following steps: S1: Weigh 10 g of polyether F-68, add 120 mL of dichloromethane, place it in an ice-salt bath and stir evenly, add 1.2 g of triethylamine, and introduce nitrogen protection. Slowly add 20 mL of dichloromethane solution containing 0.3 g of benzenesulfonyl chloride, react at room temperature for 24 h. After the reaction, add 200 mL of deionized water, extract with dichloromethane, and wash the organic phase with saturated sodium chloride solution. Rotate and evaporate to concentrate the organic phase, add the organic phase to ice ether for precipitation, filtration, and vacuum drying to obtain an intermediate; 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. Under nitrogen protection, stir and react at 80 °C for 12 h. Add 200 mL of deionized water, extract with dichloromethane, and wash the organic phase with saturated sodium chloride solution. Rotate and evaporate to concentrate the organic phase, precipitate the organic phase with ice ether, filter, and vacuum dry to obtain the product; The hydrogel in this example is carboxymethyl chitosan; The preparation method of the cutting fluid for metal processing in this example includes the following steps: Weigh 2 g of dodecanedioic acid and 4 g of triethanolamine, react at 90 °C for 30 min. After cooling, 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 quickly mix evenly at 2 °C to obtain the product.

[0032] Example 2 The cutting fluid for metal processing in this example is composed of the following components in parts by weight: 600 parts of water, 16 parts of modified surfactant, 24 parts of hydrogel, 5 parts of sebacic acid, 5 parts of hydroxyethyl hexahydro-s-triazine, and 10 parts of diethanolamine; the hydrogel is polyethyleneimine; The preparation method of the modified surfactant in this example includes the following steps: S1: Weigh 10 g of polyether F-108, add 120 mL of dichloromethane, place it in an ice-salt bath and stir evenly. Add 1.2 g of triethylamine, and introduce nitrogen for protection. Slowly add 20 mL of a dichloromethane solution containing 0.5 g of benzenesulfonyl chloride. React at room temperature for 12 h. After the reaction is completed, add 150 mL of deionized water, extract with dichloromethane, and wash the organic phase with saturated sodium chloride solution. Rotate and evaporate to concentrate the organic phase. Add the organic phase to ice-cold diethyl ether for precipitation, filtration, and vacuum drying to obtain the intermediate; 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. Under nitrogen protection, stir and react at 100 °C for 6 h. Add 150 mL of deionized water, extract with dichloromethane, and wash the organic phase with saturated sodium chloride solution. Rotate and evaporate to concentrate the organic phase. Precipitate the organic phase with ice-cold diethyl ether, filter, and vacuum dry to obtain the product; The preparation method of the hydrogel in this example includes the following steps: Weigh 5 g of polyethyleneimine, dissolve it in 100 g of water, mix evenly, add 10 g of a 2% graphene oxide aqueous solution by mass fraction, stir evenly, react at 60 °C for 8 h, store at -20 °C for 24 h, and then perform freeze-drying and grinding to obtain the product; The preparation method of the cutting fluid for metal processing in this example includes the following steps: Weigh 5 g of sebacic acid and 10 g of diethanolamine, react at 90 °C for 60 min. After cooling, add 20 g of polyethyleneimine and 650 g of water, stir at room temperature for 6 h, add 20 g of modified surfactant and 5 g of hydroxyethyl hexahydro-s-triazine, and quickly mix evenly at 6 °C to obtain the product.

[0033] Example 3 The cutting fluid for metal processing in this example 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; The preparation method of the said modified surfactant includes the following steps: S1: Weigh 10 g of polyether P-123, add 120 mL of dichloromethane, place it in an ice-salt bath and stir evenly. Add 1.2 g of triethylamine, and introduce nitrogen for protection. Slowly add 20 mL of a dichloromethane solution containing 0.4 g of benzenesulfonyl chloride. React at room temperature for 10 h. After the reaction is completed, add 150 mL of deionized water, extract with dichloromethane, and wash the organic phase with saturated sodium chloride solution. Rotate and evaporate to concentrate the organic phase. Add the organic phase to ice-cold diethyl ether for precipitation, filtration, and vacuum drying to obtain the intermediate; 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. Under nitrogen protection, react with stirring at 95 °C for 8 h. Add 150 mL of deionized water, extract with dichloromethane, and wash the organic phase with saturated sodium chloride solution. Rotavaporize and concentrate the organic phase, precipitate the organic phase with ice ether, filter, and dry in vacuum to obtain the product; The preparation method of the hydrogel in this example includes the following steps: Weigh 2 g of carboxymethyl chitosan and 3 g of polyethyleneimine, dissolve them in 100 g of water, mix evenly, add 40 g of an aqueous solution of graphene oxide with a mass fraction of 2%, stir evenly, react at 80 °C for 4 h, freeze at -20 °C for 24 h, and then perform freeze-drying and grinding to obtain the product; In this example, the graphene oxide is modified by a method including the following steps: Weigh 1 g of graphene oxide and 200 mL of N,N-dimethylformamide, ultrasonically disperse for 1 h, add 40 g of triethanolamine oleate with stirring, introduce nitrogen for 20 min, add 0.5 g of azobisisobutyronitrile, react at 65 °C for 24 h, after cooling, precipitate with methanol, dissolve the precipitate with N,N-dimethylformamide, perform centrifugal separation and vacuum drying to obtain the product; The preparation method of the cutting fluid for metal processing in this example includes the following steps: Weigh 4 g of sebacic acid and 7 g of isopropanolamine, react at 90 °C for 45 min, after cooling, add 15 g of hydrogel and 440 g of water, stir at room temperature for 6 h, add 15 g of modified surfactant and 3 g of hydroxyethyl hexahydro-s-triazine, and mix evenly quickly at 4 °C to obtain the product.

[0034] Comparative Example 1 The cutting fluid for metal processing in 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; The hydrogel in this comparative example is carboxymethyl chitosan; The preparation method of the cutting fluid for metal processing in this comparative example includes the following steps: Weigh 2 g of dodecanedioic acid and 4 g of triethanolamine, react at 90 °C for 30 min, after cooling, add 10 g of carboxymethyl chitosan and 280 g of water, stir at room temperature for 6 h, add 10 g of polyether F-68 and 2 g of hydroxyethyl hexahydro-s-triazine, and mix evenly to obtain the product.

[0035] Performance detection test 1. Degradation test of crosslinked hydrogel In this experiment, the degradation rate of the crosslinked hydrogel formed in the cutting fluid for metal processing in Example 1 under different pH conditions was used to characterize the degree of imine bond destruction. The greater the degradation rate, the more imine bonds were destroyed. Weigh 10 mL of the cutting fluid for metal processing in Example 1 and place 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. When 0 days, 1 day, 3 days, 5 days, 7 days, 15 days, and 30 days have passed, remove the solution, dry the moisture, weigh it, and calculate the degradation rate of the crosslinked hydrogel in the cutting fluid = W0 - W t / W t × 100%. In the formula, W0 is the mass after drying the moisture when the cutting fluid is not placed in the phosphate buffer solution; W t is the mass after drying the moisture when the cutting fluid is placed in the phosphate buffer solution for the t-th day. The change curve of the degradation rate of the crosslinked hydrogel in the cutting fluid with the placement time is as Figure 1 shown.

[0036] 2. Rust prevention, corrosion resistance, and lubricity tests Refer to the standard GB / T6144-2010 "Synthetic Cutting Fluid" for rust prevention and corrosion resistance tests; use a Reichert friction and wear testing machine to test the wear scar area of the test column and the weight loss of the test column to evaluate lubricity. The results are shown in Table 1.

[0037] Table 1 Performance of the cutting fluids for metal processing in Examples 1 - 3 and Comparative Example 1 3. Scanning electron microscopy observation Observe the microscopic morphology of the hydrogels prepared through Example 2 and Example 3 by scanning electron microscopy, as Figure 2 shown.

[0038] Result analysis It can be seen from Figure 1 that as the pH of the cutting fluid for metal processing decreases, the degradation rate of the crosslinked hydrogel increases significantly. This is because when the pH is low, the imine bond breaks, the crosslinking points of the crosslinked hydrogel are destroyed, and the crosslinked hydrogel degrades.

[0039] Comparing the data of the examples and comparative examples in Table 1, it can be seen that the rust prevention performance, anti-corrosion performance and lubrication performance of the cutting fluid for metal processing in the examples are better. This may be because during the use of the cutting fluid, the cross-linked hydrogel can release rust inhibitors, antibacterial agents, etc. at a lower pH, which can effectively reduce the rusting, corrosion of tools, workpieces, etc. and the 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 weight loss and wear scar area of the cutting fluid are smaller, indicating that the wear resistance and lubrication performance of the cutting fluid are better. When unsaturated acid triethanolamine is grafted onto the surface of graphene oxide, the wear resistance and lubrication performance are further improved.

[0040] From Figure 2 it can be seen that the lamellar graphene oxide was successfully introduced into the hydrogel in Example 2, and the long-chain polymer was successfully grafted onto the hydrogel in Example 3. The introduction of graphene oxide and long-chain polymer is beneficial to improving the lubrication performance of the cutting fluid.

[0041] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A cutting fluid for metal processing, characterized in that, It comprises components in the following parts by weight: 280 - 600 parts of water, 10 - 16 parts of modified surfactant, 10 - 24 parts of hydrogel, 2 - 5 parts of rust inhibitor, 2 - 5 parts of antibacterial agent, and 4 - 10 parts of pH regulator; the hydrogel is at least one of carboxymethyl chitosan and polyethyleneimine; the preparation method of the modified surfactant comprises the following steps: S1: React polyether with 4 - toluenesulfonyl chloride under nitrogen protection to obtain an intermediate; S2: React the intermediate with aldehyde under nitrogen protection to obtain the product.

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

3. The cutting fluid for metal processing according to claim 1, characterized in that, The pH value of the cutting fluid for metal processing is 8 - 10.

4. The cutting fluid for metal processing according to claim 1, characterized in that, It includes at least one of the following technical features: B1) In step S1, the polyether is one or more of polyether P - 123, polyether F - 108, and polyether F - 68; B2) In step S1, the mass ratio of the polyether to 4 - toluenesulfonyl chloride is 10:(0.3 - 0.5).

5. The cutting fluid for metal processing according to claim 1, characterized in that, It includes 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).

6. The cutting fluid for metal processing according to claim 1, characterized in that, The hydrogel is modified by a method comprising the following steps: Dissolve the hydrogel in water, add an aqueous solution of graphene oxide for reaction, and then perform freeze - drying and grinding to obtain the product.

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

8. The cutting fluid for metal processing according to claim 6, wherein, The graphene oxide is modified by a method comprising the following steps: Ultrasonically disperse graphene oxide in a solvent, add unsaturated acid triethanolamine, protect with nitrogen, add an initiator for reaction, cool after the reaction, precipitate with methanol, dissolve the precipitate, and then perform centrifugal separation and vacuum drying to obtain the product.

9. The cutting fluid for metal processing according to claim 8, characterized in that, It includes 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 graphene oxide to unsaturated acid triethanolamine is 1:(20 - 50).

10. A preparation method of a cutting fluid for metal processing according to any one of claims 1-9, characterized in that, It comprises the following steps: Heat - react the rust inhibitor and the pH regulator, cool, add water and the hydrogel, stir evenly, add the modified surfactant and the antibacterial agent, and mix evenly at 2 - 6°C to obtain the product.

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