Metal cutting fluid with excellent anti-rust performance

Abstract

The invention relates to the field of metal cutting fluid, in particular to metal cutting fluid with excellent anti-rust performance. The metal cutting fluid comprises the following components in parts by weight: 30-45 parts of base oil, 10-22 parts of a composite corrosion inhibitor, 3-7 parts of an extreme pressure lubricant, 5-10 parts of a surfactant, 8-12 parts of a pH regulator, 0.5-2 parts of a hard water resistant agent, 0.5-1.5 parts of a preservative, 0.1-0.5 part of a defoaming agent and 20-30 parts of deionized water. A plurality of corrosion inhibitors are used in the prepared metal cutting fluid to jointly form a composite corrosion inhibitor, an excellent anti-rust performance system is constructed among the corrosion inhibitor groups through a synergistic effect, compact and firm protective films can be formed on the surfaces of a plurality of metals such as cast iron, steel, aluminum alloy and copper alloy at the same time, erosion of water and oxygen is effectively blocked, and the metal cutting fluid has good corrosion resistance and corrosion resistance. And comprehensive protection on various metal materials is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of metal cutting fluid, in particular to a metal cutting fluid with excellent rust prevention performance. BACKGROUND

[0002] As an important process medium in the machining process, the main functions of metal cutting fluid include lubrication, cooling, cleaning and rust prevention. In the prior art, water-based cutting fluid is widely used due to its excellent cooling performance and environmental protection characteristics, but its rust prevention performance often fails to meet the requirements of modern precision machining. The cutting fluid products on the market have obvious deficiencies in rust prevention performance, especially in high humidity, high hardness water quality or multi-metal material collinear machining environment.

[0003] The cutting fluid in the prior art mainly faces the following problems: first, a single corrosion inhibitor is often only effective for a specific metal, and it is difficult to provide comprehensive protection for iron-based alloys, aluminum alloys, copper alloys and other metal materials. For example, it is found that fatty acid type corrosion inhibitors have significant rust prevention effect on steel materials, but when the pH value exceeds 9.0, they will cause obvious corrosion to aluminum alloys. Secondly, the hardness of water has a significant impact on the rust prevention performance of cutting fluid. When the hardness of water exceeds 318.81 ppm, the rust prevention performance of most corrosion inhibitors will decrease sharply. In addition, toxic substances such as nitrite and formaldehyde releasing agents in traditional cutting fluids pose environmental and health risks, while alternative environmentally friendly corrosion inhibitors often have insufficient rust prevention effect.

[0004] In the patent literature, CN120718706A discloses a water-based cutting fluid using glycol as the main component, which mentions rust prevention performance but does not solve the problem of multi-metal compatibility. CN120775637A uses tris(2-carboxyethyl) phosphine oxide as a rust inhibitor, emphasizing the extreme pressure effect and bactericidal performance, but it lacks protection for aluminum alloys under high pH conditions. CN119505990A provides a special cutting fluid for copper part machining, using a special antioxidant combination, but its application range is limited to copper materials, lacking universality.

[0005] In summary, there is an urgent need in the field to develop a new type of metal cutting fluid that can provide comprehensive and excellent rust protection for various metal materials without sacrificing environmental protection and safety, while adapting to different water quality conditions and machining environments. SUMMARY

[0006] In view of the problems in the prior art, the purpose of the present application is to provide a metal cutting fluid with excellent rust prevention performance.

[0007] The purpose of the present application is achieved by the following technical solution: In a first aspect, the present application provides a metal cutting fluid with excellent rust prevention performance, comprising, by weight fraction: 30-45 parts of base oil, 10-22 parts of composite corrosion inhibitor, 3-7 parts of extreme pressure lubricant, 5-10 parts of surfactant, 8-12 parts of pH regulator, 0.5-2 parts of anti-hard water agent, 0.5-1.5 parts of preservative, 0.1-0.5 parts of defoamer, and 20-30 parts of deionized water.

[0008] Preferably, the base oil is a mixture of naphthenic base oil and castor oil, and the weight ratio of naphthenic base oil to castor oil is 25-35:5-10.

[0009] More preferably, the naphthenic base oil is at least one of naphthenic base oil N4010, naphthenic base oil N4006, naphthenic base oil N4016, naphthenic base oil A1004, naphthenic base oil K6A, and naphthenic base oil K10A.

[0010] More preferably, the purity of the castor oil is USP grade.

[0011] Preferably, the composite corrosion inhibitor is a mixture of sodium petroleum sulfonate, enhanced corrosion inhibitor, triethanolamine borate, and benzotriazole, and the weight ratio of sodium petroleum sulfonate, modified corrosion inhibitor, triethanolamine borate, and benzotriazole is 3-8:5-8:2-5:0.1-0.5.

[0012] More preferably, the molecular weight of the sodium petroleum sulfonate (T702) is 450-600.

[0013] Preferably, the extreme pressure lubricant is a mixture of molybdenum dialkyldithiocarbamate (MoDTC) and oleic acid, and the weight ratio of molybdenum dialkyldithiocarbamate to oleic acid is 1-3:2-4.

[0014] Preferably, the molybdenum dialkyldithiocarbamate is molybdenum dibutyldithiocarbamate.

[0015] Preferably, the surfactant is a mixture of fatty alcohol polyoxyethylene ether and alkanolamide, and the weight ratio of fatty alcohol polyoxyethylene ether to alkanolamide is 3-6:2-4.

[0016] More preferably, the fatty alcohol polyoxyethylene ether is at least one of AEO-9, AEO-10, AEO-15, and AEO-20.

[0017] More preferably, the alkanolamide is at least one of lauryl alcoholamide, myristyl alcoholamide, and cetyl alcoholamide.

[0018] Preferably, the pH regulator is triethanolamine.

[0019] Preferably, the anti-hard water agent is tetrasodium ethylenediaminetetraacetate (EDTA-4Na).

[0020] Preferably, the preservative is isothiazolinone.

[0021] Preferably, the defoaming agent is an organic silicon defoaming agent, specifically at least one of AFE-1247, AFE-1267, AF-8014, and AFE-3168.

[0022] Preferably, the preparation method of the enhanced corrosion inhibitor comprises: S1, weigh 4, 4'-diamino diphenyl sulfone and N, N-dimethylformamide, mix under the protection of nitrogen, stir at 55-65℃ until completely dissolved, then cool to 40℃, add phthalic anhydride, continue to stir at room temperature for 10-15h, after the reaction is completed, aftertreatment is carried out to obtain the amide acid intermediate; S2, mix the amide acid intermediate and N, N-dimethylformamide, stir and heat to 70-90℃ to completely dissolve, add 4-aminobenzenesulfonamide, then add N, N'-dicyclohexyl carbodiimide and 4-dimethylaminopyridine, heat the reaction system to 100-120℃, reflux under the protection of nitrogen and stirring for 20-30h, after the reaction is completed, aftertreatment is carried out to obtain the product, the enhanced corrosion inhibitor.

[0023] Preferably, the mass ratio of 4, 4'-diamino diphenyl sulfone and phthalic anhydride is 2.48:2.96-3.7.

[0024] Preferably, the mass ratio of the amide acid intermediate and 4-aminobenzenesulfonamide is 1:1.72-2.58.

[0025] Preferably, the mass ratio of N, N'-dicyclohexyl carbodiimide, 4-dimethylaminopyridine and 4-aminobenzenesulfonamide is 2.06-2.47:0.12-0.2:1.72-2.58.

[0026] In a second aspect, the present application provides a preparation method of a metal cutting fluid with excellent rust prevention performance, comprising the following steps: Step 1, mix the anti-hard water agent, the surfactant and the deionized water into a container, stir uniformly at 60-65℃, then add the composite corrosion inhibitor again, stir again to form the water phase; Step 2, take the base oil into another container, heat to 45-55℃, then add the extreme pressure lubricant until all components are uniformly mixed to form the oil phase; Step 3, the oil phase prepared in step 2 is slowly added into the water phase of step 1 at a speed of 30-50 mL / min and a temperature of 50-60℃, and then shearing emulsification is carried out at a shearing speed of 2000-3000 rpm for 30-45 min to obtain an emulsion; Step 4, the stirring speed is reduced to 500-600 rpm, and then the pH regulator, the preservative and the defoaming agent are sequentially added into the emulsion, and the stirring is continuously carried out to uniformly mix all the components; Step 5, the heating is stopped, and the emulsion is naturally cooled to room temperature, and then impurities are removed through a 200-mesh filter screen to obtain a transparent to translucent emulsion, i.e., a metal cutting fluid.

[0027] The present application has the following beneficial effects: 1. The metal cutting fluid prepared in the present application uses multiple corrosion inhibitors to form a composite corrosion inhibitor, and the corrosion inhibitor groups are combined to form an excellent rust prevention system through synergistic effect, so that a dense and firm protective film can be formed on the surfaces of cast iron, steel, aluminum alloy and copper alloy, etc., to effectively prevent the erosion of water and oxygen, and to comprehensively protect various metal materials, thereby solving the problem of narrow protection range of single corrosion inhibitor in the prior art.

[0028] 2. The formula of the present application discards toxic and harmful substances such as nitrite, phenol and formaldehyde release, and the selected base oil, corrosion inhibitor and functional additive all meet the environmental protection requirements. At the same time, the cutting fluid of the present application has excellent rust prevention performance, good lubricity and extreme pressure and wear resistance, can effectively reduce tool wear, improve the surface processing quality of workpieces, and fully exert the inherent advantages of high cooling efficiency of water-based cutting fluid.

[0029] 3. In the composite corrosion inhibitor used in the present application, the sodium petroleum sulfonate has strong lipophilicity on one end and gold affinity on the other end, and can be adsorbed on the metal surface to form a hydrophobic monomolecular oriented film; the rigid aromatic skeleton in the enhanced corrosion inhibitor can be laid on the metal surface, and also contains multiple polar functional groups, which can form a firm coordination bond with the metal surface; triethanolamine borate can stabilize the pH value by acting together with triethanolamine in the system, and can also form a complex with metal ions to play a dynamic repair role; benzotriazole is a special corrosion inhibitor for copper and copper alloy, which makes up for the protection ability for copper alloy parts.

[0030] 4、Enhanced corrosion inhibitor first through 4,4'-diamino diphenyl sulfone and phthalic anhydride anhydride and primary amine ring-opening acylation reaction, forming both ends with linear molecules with active carboxyl; then with 4-aminobenzenesulfonamide carboxyl and primary amine dehydration condensation reaction, introducing the anti-rust function of sulfonamide group. Among them, the diphenyl sulfone skeleton provides thermal stability and chemical stability, its rigid planar structure helps the molecule to arrange closely on the metal surface; double phthalimide has excellent physical adsorption capacity, adsorbed on the metal surface to provide a basic barrier; sulfonamide group forms a coordination bond with the metal surface through N, O atoms and empty orbitals, producing strong and firm chemical adsorption. DETAILED DESCRIPTION

[0031] The technical solutions of the present application are described below through specific examples. It should be understood that the one or more method steps mentioned in the present application do not exclude the existence of other method steps before and after the combination steps or the insertion of other method steps between the explicitly mentioned steps; it should also be understood that these examples are only used to illustrate the present application and not to limit the scope of the present application. Moreover, unless otherwise stated, the numbering of each method step is only a convenient tool to identify each method step, and is not a limitation on the arrangement order or the scope of the present application that can be implemented. The change or adjustment of the relative relationship is also considered as the scope of the present application that can be implemented without substantial changes in technical content.

[0032] In order to better understand the above technical solutions, the exemplary embodiments of the present application are described in more detail below. Although exemplary embodiments of the present application are shown, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present application and to convey the scope of the present application to those skilled in the art.

[0033] The present application is further described below in conjunction with the following examples.

[0034] Example 1 A metal cutting fluid with excellent rust prevention performance, according to the weight fraction, includes: 38 parts of base oil, 16 parts of composite corrosion inhibitor, 5 parts of extreme pressure lubricant, 7 parts of surfactant, 10 parts of pH regulator, 1.6 parts of anti-hard water agent, 1 part of preservative, 0.3 part of defoamer and 25 parts of deionized water.

[0035] Among them, the base oil is a mixture of naphthenic oil and castor oil, and the weight ratio of naphthenic oil and castor oil is 30:8. The naphthenic oil is naphthenic oil N4010; the purity of the castor oil is USP grade.

[0036] The composite corrosion inhibitor is a mixture of petroleum sulfonic acid sodium (T702, molecular weight is 550), enhanced corrosion inhibitor, triethanolamine borate and benzotriazole, and the weight ratio of petroleum sulfonic acid sodium, modified corrosion inhibitor, triethanolamine borate and benzotriazole is 5:6:3:0.2.

[0037] The extreme pressure lubricant is a mixture of molybdenum dibutyl dithiocarbamate and oleic acid, and the weight ratio of molybdenum dibutyl dithiocarbamate and oleic acid is 2:3.

[0038] The surfactant is a mixture of fatty alcohol polyoxyethylene ether AEO-10 and lauryl alcohol amide, and the weight ratio of fatty alcohol polyoxyethylene ether AEO-10 and lauryl alcohol amide is 5:3.

[0039] The pH regulator is triethanolamine; the anti-hard water agent is ethylenediaminetetraacetic acid tetrasodium (EDTA-4Na); the preservative is isothiazolinone; and the defoaming agent is an organic silicon defoaming agent, specifically AFE-1247.

[0040] The preparation method of the enhanced corrosion inhibitor comprises the following steps: S1, 2.48g of 4,4'-diamino diphenyl sulfone and 20mL of N,N-dimethylformamide (DMF) are weighed into a three-necked flask, the three-necked flask is placed in an oil bath, the temperature is set to 60℃ under the protection of nitrogen, and stirring is performed until the diamine is completely dissolved, then the temperature is lowered to 40℃, 3.16g of phthalic anhydride is gradually added in multiple times within 2h, the system temperature is controlled to be ≤50℃, after the addition is completed, the oil bath is removed, and the reaction is continued to stir at room temperature for 12h, the reaction system will gradually become thick, and a large amount of white solid is generated, the reaction liquid is slowly poured into a beaker containing 30mL of ice water mixture and 2mL of concentrated hydrochloric acid, and stirring is performed until no white precipitate is generated, filtration is performed, the filter cake is washed with deionized water until the washing liquid is neutral, the wet filter cake is transferred to a watch glass, and drying is performed in a 60℃ vacuum drying box for 12h to obtain a white powder, which is an amide acid intermediate; S2, take the 1 g amide acid intermediate and 20 mL N, N- dimethylformamide (DMF) mixed to a three-necked flask, stirring and heating to 80℃ to make it completely dissolved, add 2.13 g 4-aminobenzenesulfonamide stirring uniform, then again add 2.23 g condensing agent N, N'-dicyclohexyl carbodiimide (DCC) and 0.16 g catalyst 4-dimethylamino pyridine (DMAP), the reaction system is warmed to 110℃, under nitrogen protection and mechanical stirring reflux reaction 25 h, in the process, DCC and intermediate carboxyl reaction generates active ester, then with amino benzenesulfonamide amino condensation, while amide acid cyclization dehydration to form imide ring, after the reaction, the reaction liquid is cooled to room temperature, first by suction filtration to remove the solid, the filtrate is slowly poured into 20 mL ice ethanol / water (1:1) mixed solution under vigorous stirring, at this time there will be light yellow flocculent solid precipitate, suction filtration, the filter cake is washed with cold ethanol 3 times to completely remove the residual DMF, by-product and unreacted raw materials, the light yellow solid obtained in 60℃ vacuum drying oven is continuously dried for 24 hours, to obtain light yellow to yellow brown final product enhanced corrosion inhibitor.

[0041] The preparation method of the metal cutting fluid with excellent rust prevention performance includes the following steps: Step 1, mix the hard water inhibitor, surfactant and deionized water into a container, stir uniformly at 60℃, then add the composite corrosion inhibitor, stir again to form the water phase; Step 2, take the base oil into another container, heat to 50℃, then add the extreme pressure lubricant until all components are uniformly mixed to form the oil phase; Step 3, slowly add the oil phase prepared in step 2 to the water phase of step 1, the speed is controlled at 40 mL / min and the temperature is controlled at 55℃, after adding, perform shear emulsification, the shear speed is 2500 rpm and the shear time is 35 in to obtain the emulsion; Step 4, reduce the stirring speed to 550 rpm, then sequentially add the pH regulator, preservative and defoaming agent into the emulsion, continuously stir to mix all components uniformly; Step 5, stop heating and naturally cool to room temperature, remove the impurities through a 200 mesh filter screen to obtain the transparent to translucent emulsion, that is, the metal cutting fluid.

[0042] Example 2 A metal cutting fluid with excellent rust prevention performance, according to weight fraction, includes: 30 parts of base oil, 10 parts of composite corrosion inhibitor, 3 parts of extreme pressure lubricant, 5 parts of surfactant, 8 parts of pH regulator, 0.5 parts of hard water inhibitor, 0.5 parts of preservative, 0.1 parts of defoaming agent and 20 parts of deionized water.

[0043] The base oil is a mixture of naphthenic oil and castor oil, and the weight ratio of naphthenic oil to castor oil is 25:5. The naphthenic oil is naphthenic oil N4006; and the purity of the castor oil is USP grade.

[0044] The composite corrosion inhibitor is a mixture of sodium petroleum sulfonate (T702, molecular weight 550), enhanced corrosion inhibitor (prepared by the same method as in Example 1), triethanolamine borate, and benzotriazole, and the weight ratio of sodium petroleum sulfonate, modified corrosion inhibitor, triethanolamine borate, and benzotriazole is 3:5:2:0.1.

[0045] The extreme pressure lubricant is a mixture of molybdenum dibutyl dithiocarbamate and oleic acid, and the weight ratio of molybdenum dibutyl dithiocarbamate to oleic acid is 1:2.

[0046] The surfactant is a mixture of fatty alcohol polyoxyethylene ether and alkanolamide, and the weight ratio of fatty alcohol polyoxyethylene ether to alkanolamide is 3:2. The fatty alcohol polyoxyethylene ether is AEO-9; and the alkanolamide is tetradecyl alkanolamide.

[0047] The pH regulator is triethanolamine; the anti-hard water agent is ethylenediaminetetraacetic acid tetrasodium (EDTA-4Na); the preservative is isothiazolinone; and the defoaming agent is an organic silicon defoaming agent, specifically AFE-1267.

[0048] The preparation method of the metal cutting fluid with excellent rust prevention performance comprises the following steps: Step 1: Mix the anti-hard water agent, surfactant, and deionized water into a container, stir uniformly at 60°C, then add the composite corrosion inhibitor, and stir again to form an aqueous phase; Step 2: Take the base oil into another container, heat to 45°C, then add the extreme pressure lubricant, and mix all components uniformly to form an oil phase; Step 3: Slowly add the oil phase prepared in Step 2 to the aqueous phase of Step 1 at a speed of 30 mL / min and a temperature of 50-60°C, then perform shear emulsification at a shear speed of 2000 rpm for 30 min to obtain an emulsion; Step 4: Reduce the stirring speed to 500 rpm, then sequentially add the pH regulator, preservative, and defoaming agent to the emulsion, and continuously stir to mix all components uniformly; Step 5: Stop heating, naturally cool to room temperature, remove impurities through a 200-mesh filter screen, and obtain a transparent to translucent emulsion, i.e., a metal cutting fluid.

[0049] Example 3 A metal cutting fluid with excellent rust prevention performance, according to weight fractions, comprises: 45 parts of base oil, 22 parts of composite corrosion inhibitor, 7 parts of extreme pressure lubricant, 10 parts of surfactant, 12 parts of pH regulator, 2 parts of anti-hard water agent, 1.5 parts of preservative, 0.5 parts of defoamer and 30 parts of deionized water.

[0050] The base oil is a mixture of naphthenic oil and castor oil, and the weight ratio of naphthenic oil to castor oil is 35:10. The naphthenic oil is naphthenic oil N4016, and the purity of the castor oil is USP grade.

[0051] The composite corrosion inhibitor is a mixture of sodium petroleum sulfonate (T702, molecular weight 450-600), enhanced corrosion inhibitor (prepared by the same method as in Example 1), triethanolamine borate and benzotriazole, and the weight ratio of sodium petroleum sulfonate, modified corrosion inhibitor, triethanolamine borate and benzotriazole is 8:8:5:0.5.

[0052] The extreme pressure lubricant is a mixture of molybdenum dibutyl dithiocarbamate and oleic acid, and the weight ratio of molybdenum dibutyl dithiocarbamate to oleic acid is 3:4.

[0053] The surfactant is a mixture of fatty alcohol polyoxyethylene ether and alkanolamide, and the weight ratio of fatty alcohol polyoxyethylene ether to alkanolamide is 6:4. The fatty alcohol polyoxyethylene ether is AEO-15. The alkanolamide is hexadecanol amide.

[0054] The pH regulator is triethanolamine; the anti-hard water agent is ethylenediaminetetraacetic acid tetrasodium (EDTA-4Na); the preservative is isothiazolinone; and the defoamer is an organic silicon defoamer, specifically AFE-3168.

[0055] The preparation method of the metal cutting fluid with excellent rust prevention performance comprises the following steps: Step 1: Mix the anti-hard water agent, surfactant and deionized water into a container, stir uniformly at 65°C, then add the composite corrosion inhibitor, and stir again to form an aqueous phase; Step 2: Take the base oil into another container, heat to 55°C, then add the extreme pressure lubricant, and mix all the components uniformly to form an oil phase; Step 3: Slowly add the oil phase prepared in Step 2 to the aqueous phase of Step 1 at a speed of 50 mL / min and a temperature of 60°C, and then perform shear emulsification at a shear speed of 3000 rpm for 45 min to obtain an emulsion; Step 4: Reduce the stirring speed to 600 rpm, then sequentially add the pH regulator, preservative and defoamer to the emulsion, and continuously stir to mix all the components uniformly; Step 5, stop heating, naturally cool to room temperature, remove impurities through a 200 mesh filter screen to obtain a transparent to translucent emulsion, i.e. metal cutting fluid.

[0056] Example 4 A metal cutting fluid with excellent rust prevention performance, which is only different from Example 1 in that the preparation method of the enhanced corrosion inhibitor is different.

[0057] The preparation method of the enhanced corrosion inhibitor comprises: S1, weigh 2.48g of 4,4'-diamino diphenyl sulfone and 20mL of N,N-dimethylformamide (DMF) into a three-necked flask, then place the three-necked flask in an oil bath, set the temperature to 65℃ under the protection of nitrogen, stir until the diamine is completely dissolved, then cool to 40℃, gradually add 3.7g of phthalic anhydride in multiple times within 2h, control the system temperature ≤50℃, after the addition is completed, remove the oil bath, continue to stir at room temperature for 15h, the reaction system will gradually thicken, and a large amount of white solid will be generated, slowly pour the reaction liquid into a beaker containing 30mL of ice water mixture and 2mL of concentrated hydrochloric acid, stir vigorously until no more white precipitate is generated, filter, wash the filter cake with deionized water until the washing liquid is neutral, transfer the wet filter cake to a watch glass, dry in a 70℃ vacuum drying oven for 12h to obtain a white powder, i.e. amide acid intermediate; S2, mix 1g of the amide acid intermediate obtained in S1 and 20mL of N,N-dimethylformamide (DMF) into a three-necked flask, stir and heat to 70-90℃ to completely dissolve, add 2.58g of 4-aminobenzenesulfonamide, stir uniformly, then add 2.47g of condensing agent N,N'-dicyclohexyl carbodiimide (DCC) and 0.2g of catalyst 4-dimethylaminopyridine (DMAP) again, raise the reaction system to 120℃, reflux for 30h under the protection of nitrogen and mechanical stirring, in this process, DCC reacts with the carboxyl group of the intermediate to generate active ester, which then condenses with the amino group of aminobenzenesulfonamide, while the amide acid ring is cyclized and dehydrated to form an imide ring, after the reaction is completed, cool the reaction liquid to room temperature, first remove the solid by filtration, slowly pour the filtrate into a mixture of 20mL of ice ethanol / water (1:1) under vigorous stirring, at this time, light yellow flocculent solid will precipitate, filter, wash the filter cake with cold ethanol 3 times to completely remove residual DMF, byproducts and unreacted raw materials, continuously dry the light yellow to yellow brown final product, i.e. enhanced corrosion inhibitor, in a 70℃ vacuum drying oven for 24h.

[0058] Example 5 A metal cutting fluid with excellent rust prevention performance, which is only different from Example 1 in that the preparation method of the enhanced corrosion inhibitor is different.

[0059] The preparation method of the enhanced corrosion inhibitor comprises: S1, 2.48 g of 4,4'-diamino diphenyl sulfone and 20 mL of N,N-dimethylformamide (DMF) were weighed into a three-necked flask, and the three-necked flask was placed in an oil bath, under the protection of nitrogen, the temperature was set to 55°C, and stirring was performed until the diamine was completely dissolved, then the temperature was lowered to 40°C, 2.96 g of phthalic anhydride was gradually added in multiple times within 2 h, the temperature of the system was controlled to be ≤50°C, after the addition was completed, the oil bath was removed, and the reaction was continued to stir at room temperature for 10 h, the reaction system gradually became thick, and a large amount of white solid was generated, the reaction liquid was slowly poured into a beaker containing 30 mL of ice water mixture and 2 mL of concentrated hydrochloric acid, and stirring was performed until no more white precipitate was generated, filtration was performed, the filter cake was washed with deionized water until the washing liquid was neutral, the wet filter cake was transferred to a watch glass, and drying was performed in a vacuum drying oven at 60-70°C for 12 h to obtain a white powder, which was an amide acid intermediate; S2, 1 g of the amide acid intermediate obtained in S1 and 20 mL of N,N-dimethylformamide (DMF) were mixed into a three-necked flask, stirring was performed and heating was performed to 70°C until complete dissolution, 1.72 g of 4-aminobenzenesulfonamide was added and uniformly stirred, then 2.06 g of a condensing agent N,N'-dicyclohexyl carbodiimide (DCC) and 0.12 g of a catalyst 4-dimethylaminopyridine (DMAP) were added again, the reaction system was warmed to 100°C, and refluxing was performed under the protection of nitrogen and mechanical stirring for 20 h, in this process, DCC reacted with the carboxyl group of the intermediate to generate an active ester, and then the active ester reacted with the amino group of the aminobenzenesulfonamide to condense, while the amide acid was cyclized and dehydrated to form an imide ring, after the reaction was completed, the reaction liquid was cooled to room temperature, first, solid was removed through filtration, the filtrate was slowly poured into a mixture of 20 mL of ice ethanol / water (1:1) under vigorous stirring, at this time, light yellow flocculent solid was precipitated, filtration was performed, the filter cake was washed with cold ethanol for 3 times to completely remove residual DMF, byproducts and unreacted raw materials, and the light yellow solid obtained was continuously dried in a vacuum drying oven at 60°C for 24 hours to obtain a light yellow to yellow brown final product, which was an enhanced corrosion inhibitor.

[0060] Comparative Example 1 A metal cutting fluid, which is only different from Example 1 in that the enhanced corrosion inhibitor is not added.

[0061] Comparative Example 2 A metal cutting fluid, which is only different from Example 1 in that the enhanced corrosion inhibitor is replaced by an amide acid intermediate (which is prepared in the same way as S1 of Example 1).

[0062] Comparative Example 3 A metal cutting fluid, which is only different from Example 1 in that the enhanced corrosion inhibitor is replaced by 4-aminobenzenesulfonamide.

[0063] Experimental detection The performance of the metal cutting fluid prepared in Example 1, Comparative Examples 1-3 was detected and compared, including rust prevention performance, stability and extreme pressure lubricity, wherein the rust prevention performance included cast iron chip filter paper method, cast iron single piece, aluminum alloy and copper alloy detection, the detection standard was GB / T 6144-2010; the stability included hard water stability and high temperature stability, the detection standard was GB / T 6144-2010; the extreme pressure lubricity detection included maximum non-galling load, the reference standard was GB / T 3142-2019.

[0064] The results are shown in Table 1:

[0065] As shown in Table 1, Example 1 performed excellently in the rust prevention tests of cast iron, aluminum alloy and copper alloy, which proved that its formula could form an effective protective film on different metal surfaces. In contrast, Comparative Example 1 (without adding enhanced corrosion inhibitor) and Comparative Example 3 (using only 4-aminobenzenesulfonamide) had the worst protective effect, and Comparative Example 2 (using amide acid intermediate) was better than Comparative Examples 1 and 3, but not as good as Example 1, indicating that the enhanced corrosion inhibitor is the core of the entire rust prevention system. In addition, Example 1 also showed excellent extreme pressure lubricity, which is beneficial to protect the tool and workpiece; at the same time, it also has the best stability in hard water and high temperature conditions, indicating that the emulsion system in Example 1 has excellent compatibility.

[0066] In the description of the present specification, the description referring to the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms should not be understood as necessarily referring to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in the present specification.

[0067] Although the embodiments of the present application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. A metal cutting fluid with excellent rust-preventive properties, characterized in that, Calculated by weight, including: 30-45 parts base oil, 10-22 parts compound corrosion inhibitor, 3-7 parts extreme pressure lubricant, 5-10 parts surfactant, 8-12 parts pH adjuster, 0.5-2 parts anti-hard water agent, 0.5-1.5 parts corrosion inhibitor, 0.1-0.5 parts defoamer, and 20-30 parts deionized water; The composite corrosion inhibitor is a mixture of sodium petroleum sulfonate, a modified corrosion inhibitor, triethanolamine borate, and benzotriazole, wherein the weight ratio of sodium petroleum sulfonate, modified corrosion inhibitor, triethanolamine borate, and benzotriazole is 3-8:5-8:2-5:0.1-0.

5.

2. The metal cutting fluid with excellent rust-preventive properties according to claim 1, characterized in that, The base oil is a mixture of naphthenic oil and castor oil, with a weight ratio of naphthenic oil to castor oil of 25-35:5-10.

3. The metal cutting fluid with excellent rust-preventive properties according to claim 1, characterized in that, The extreme pressure lubricant is a mixture of molybdenum dialkyldithiocarbamate and oleic acid, with a weight ratio of molybdenum dialkyldithiocarbamate to oleic acid of 1-3:2-4.

4. The metal cutting fluid with excellent rust-preventive properties according to claim 1, characterized in that, The surfactant is a mixture of fatty alcohol polyoxyethylene ether and alkanolamide, with a weight ratio of fatty alcohol polyoxyethylene ether to alkanolamide of 3-6:2-4; wherein the fatty alcohol polyoxyethylene ether is at least one of AEO-9, AEO-10, AEO-15, and AEO-20; and the alkanolamide is at least one of dodecyl alcoholamide, tetradecyl alcoholamide, and hexadecyl alcoholamide.

5. A metal cutting fluid with excellent rust-preventive properties according to claim 1, characterized in that, The pH adjuster is triethanolamine; the water hardening agent is tetrasodium ethylenediaminetetraacetate; and the preservative is isothiazolinone.

6. A metal cutting fluid with excellent rust-preventive properties according to claim 1, characterized in that, The defoamer is an organosilicon defoamer, specifically at least one of AFE-1247, AFE-1267, AF-8014, and AFE-3168.

7. A metal cutting fluid with excellent rust-preventive properties according to claim 1, characterized in that, The preparation method of the enhanced corrosion inhibitor includes: S1. Weigh 4,4'-diaminodiphenyl sulfone and N,N-dimethylformamide and mix them. Under nitrogen protection, stir at 55-65℃ until completely dissolved, then cool to 40℃, add phthalic anhydride, and continue stirring at room temperature for 10-15 hours. After the reaction is completed, after post-treatment, the amic acid intermediate is obtained. S2. Mix the ammonium acid intermediate and N,N-dimethylformamide, stir and heat to 70-90℃ to completely dissolve it, add 4-aminobenzenesulfonamide, then add N,N'-dicyclohexylcarbodiimide and 4-dimethylaminopyridine, heat the reaction system to 100-120℃, and reflux under nitrogen protection and stirring for 20-30 hours. After the reaction is completed, after post-treatment, the product enhanced corrosion inhibitor is obtained.

8. A metal cutting fluid with excellent rust-preventive properties according to claim 7, characterized in that, The mass ratio of 4,4'-diaminodiphenyl sulfone to phthalic anhydride is 2.48:2.96-3.7; the mass ratio of amyl acid intermediate to 4-aminobenzenesulfonamide is 1:1.72-2.

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9. A metal cutting fluid with excellent rust-preventive properties according to claim 7, characterized in that, The mass ratio of N,N'-dicyclohexylcarbodiimide, 4-dimethylaminopyridine, and 4-aminobenzenesulfonamide is 2.06-2.47:0.12-0.2:1.72-2.

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10. A method for preparing a metal cutting fluid with excellent rust-preventing properties as described in claim 1, characterized in that, Includes the following steps: Step 1: Mix the anti-hard water agent, surfactant and deionized water into a container, stir evenly at 60-65℃, then add the composite corrosion inhibitor, stir thoroughly again to form an aqueous phase; Step 2: Take the base oil into another container, heat it to 45-55℃, and then add the extreme pressure lubricant until all components are evenly mixed to form an oil phase; Step 3: Slowly add the oil phase obtained in Step 2 to the aqueous phase in Step 1 at a rate of 30-50 mL / min and a temperature of 50-60℃. After addition, perform shear emulsification at a shear rate of 2000-3000 rpm for 30-45 min to obtain the emulsion. Step 4: Reduce the stirring speed to 500-600 rpm, then add the pH adjuster, preservative and defoamer to the emulsion in sequence, and continue stirring to mix all components evenly. Step 5: Stop heating, allow to cool naturally to room temperature, and pass through a 200-mesh filter to remove impurities, resulting in a transparent to semi-transparent emulsion, i.e., metal cutting fluid.

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