Environment-friendly antibacterial water-soluble cooling liquid and preparation method thereof

Abstract

The invention relates to environment-friendly antibacterial water-soluble cooling liquid and a preparation method thereof, and belongs to the technical field of cooling liquid. Comprising the following raw materials in percentage by weight: 30%-50% of environment-friendly composite oil, 6%-8% of dicyclohexylamine, 4%-5% of a surfactant, 3%-5% of a modified graphene nanofluid, 2.5%-3.5% of ethylene glycol butyl ether, 1%-2% of a pH adjusting stabilizer, 0.8%-1.2% of alcohol ether carboxylic acid, 0.4%-0.6% of dodecanedioic acid, 0.2%-0.4% of benzotriazole, 0.1%-0.3% of an organic silicon defoaming agent and the balance of deionized water. The formula and the preparation process of the cooling liquid have the characteristics of being green and environment-friendly, and the prepared cooling liquid has good antibacterial activity.

Description

Technical Field

[0001] The present invention belongs to the technical field of coolant, and relates to an environmentally friendly antibacterial water-soluble coolant and a preparation method thereof. Background Art

[0002] During the metal cutting process, the coolant plays a crucial role. It can not only cool the cutting tool and the workpiece being processed, reduce the cutting heat, but also provide necessary lubrication, reduce the cutting force and friction, thereby prolonging the metal life and improving the machining surface quality. However, traditional coolants often contain harmful components such as boron and chlorine, which may cause environmental pollution during use and are also not conducive to the health of operators. In addition, some coolants are prone to bacterial growth during use, resulting in the deterioration and odor of the cutting fluid, which not only affects the machining effect but may also cause corrosion to the equipment and workpieces. Therefore, it is particularly important to develop a cutting fluid that is both environmentally friendly and has antibacterial properties. Summary of the Invention

[0003] The purpose of the present invention is to provide an environmentally friendly antibacterial water-soluble coolant and a preparation method thereof, which have the characteristics of environmental friendliness and good antibacterial properties.

[0004] The purpose of the present invention can be achieved by the following technical solutions:

[0005] An environmentally friendly antibacterial water-soluble coolant, the formula of the water-soluble coolant is as follows, by weight percentage, 30% - 50% of environmentally friendly composite oil, 6% - 8% of dicyclohexylamine, 4% - 5% of surfactant, 3% - 5% of modified graphene nanofluid, 2.5% - 3.5% of ethylene glycol monobutyl ether, 1% - 2% of pH adjustment stabilizer, 0.8% - 1.2% of alcohol ether carboxylic acid, 0.4% - 0.6% of dodecanedioic acid, 0.2% - 0.4% of benzotriazole, 0.1% - 0.3% of organosilicon defoamer, and the balance is deionized water.

[0006] Among them, the preparation method of the environmentally friendly composite oil is as follows:

[0007] S1-1: Place a mixture of 20 - 30 parts by weight of castor oil and tall oil at a temperature of 40 - 50 °C and stir at a speed of 600 - 700 r / min for 30 min. Add 30 parts by weight of naphthenic base oil, raise the speed to 800 - 900 r / min and continue to stir at 40 - 50 °C for 30 min to obtain a mixed oil.

[0008] S1-2: Add 3 - 5 parts by weight of vanillyl alcohol to 50 - 60 parts by weight of absolute ethanol, ultrasonicate for 30 min, add 0.5 part by weight of emulsifier, continue ultrasonication for 10 min, then add the mixed oil, and stir at a speed of 750 - 850 r / min at 60 °C for 1 h to obtain the environmentally friendly composite oil.

[0009] As a preferred technical solution of the present invention, the preparation method of the modified graphene nanofluid is as follows:

[0010] S2-1: Place graphene oxide in a ball mill and ball mill for 1.5 h. The ball milling is carried out under the protection of high-purity nitrogen. Subsequently, add 10-15 parts by weight of the ball-milled graphene oxide to 100 parts by weight of absolute ethanol, ultrasonicate at 60-70 °C for 2-3 h, with an ultrasonic power of 8-10 kW, and then centrifuge in a high-speed centrifuge for 10-20 min to obtain solution A;

[0011] S2-2: Add 5-10 parts by weight of polyethylene glycol to solution A, stir at a speed of 650-750 r / min at 45-55 °C for 1-2 h, then add phosphate ester, raise the temperature to 80 °C and stir at a speed of 600-700 r / min for 1.5 h to obtain the modified graphene nanofluid.

[0012] As a preferred technical solution of the present invention, the pH adjustment stabilizer is a mixture of triethanolamine and AMP95 special amine in a mass ratio of 1:(1-2).

[0013] As a preferred technical solution of the present invention, the surfactant is one or both of fatty alcohol polyoxyethylene ether and sodium fatty alcohol polyoxyethylene ether sulfate.

[0014] As a preferred technical solution of the present invention, in the mixture of castor oil and tall oil in S1-1, the mass ratio of castor oil to tall oil is mixed at (1-3):1.

[0015] As a preferred technical solution of the present invention, the emulsifier in S1-2 is OP-10.

[0016] As a preferred technical solution of the present invention, the ball milling speed in S2-1 is 200-300 r / min.

[0017] As a preferred technical solution of the present invention, the speed of the high-speed centrifuge in S2-1 is set at 8000-10000 r / min.

[0018] As a preferred technical solution of the present invention, the addition amount of the phosphate ester in S2-2 is 3%-5% of the mass of solution A.

[0019] A preparation method of an environmentally friendly antibacterial water-soluble coolant, the specific steps of the preparation method are as follows:

[0020] Mix the environmentally friendly composite oil, dicyclohexylamine, surfactant, modified graphene nanofluid, ethylene glycol monobutyl ether, pH adjustment stabilizer, alcohol ether carboxylic acid, dodecanedioic acid, benzotriazole, silicone defoamer and deionized water according to the formula ratio, homogenize at 40 - 50 °C for 1 - 2 h, and then let it stand at room temperature for 8 - 12 h to obtain the environmentally friendly antibacterial water-soluble coolant.

[0021] Castor oil, as a non-edible vegetable oil that is not prone to oxidative acidification in the air, has fewer unsaturated bonds in its molecular structure. Therefore, it has good antioxidant properties, enabling it to resist the erosion of oxygen in the air, with good storage stability, thus extending the service life of the coolant. Castor oil also has excellent lubricity and fluidity and can be used as an ideal lubricating oil and protective oil. At the same time, ricinoleic acid contained in castor oil has antibacterial properties and can effectively inhibit the growth of bacteria, preventing the coolant from being contaminated during use. The natural acidic components contained in tall oil can form a protective film inside the cooling system, effectively preventing the corrosion and rust of metal components. Naphthenic base oil, with its good thermal stability and chemical stability, provides protection for the coolant in high-temperature and oxidation environments, further ensuring the durability and reliability of the coolant. In addition, the addition of vanillin not only adds an aroma to the coolant but also synergistically acts with castor oil to enhance the antibacterial properties of the coolant. Absolute ethanol, as a solvent, not only promotes the uniform mixing and dispersion of each component but also, due to its good volatility, helps to improve the cooling effect of the coolant. In addition, ethanol can also play a certain antibacterial role in the coolant. Emulsifier OP-10 ensures the stable combination of the oil phase and the water phase through its unique emulsification effect, making the coolant maintain good water solubility and stability.

[0022] The environmentally friendly composite oil has excellent lubricating properties. The lubricity of castor oil and tall oil and the stability of naphthenic base oil jointly ensure that the coolant can effectively reduce friction and wear during the circulation process, protecting all components of the cooling system. The antibacterial and antioxidant properties of vanillin and castor oil, as well as the stability of the environmentally friendly composite oil system, help to inhibit the growth of bacteria and other microorganisms, preventing the coolant from being contaminated and deteriorating during use. The combined action of emulsifier OP-10 and naphthenic base oil ensures the stability of the coolant in high-temperature and high-pressure environments for a long time, enabling it to continuously and effectively play the role of cooling and lubrication. Castor oil, tall oil, and absolute ethanol all have good biodegradability, which can reduce environmental pollution. At the same time, the entire coolant formula also meets environmental protection requirements, helping to reduce the pressure of industrial wastewater treatment.

[0023] Graphene nanofluids have high thermal conductivity and thermal diffusivity, and can absorb heat more effectively and release it into the environment, which helps to improve the thermal conversion efficiency of the coolant. Therefore, the good thermal conductivity of graphene nanofluids enables them to more effectively reduce the temperature when used as a component of the coolant. Compared with traditional coolants, graphene nanofluids also have the advantages of environmental protection and sustainability when used as coolant components. Graphene nanofluids have a lower impact on the environment and conform to the concept of green chemistry. In addition, graphene itself has good antibacterial properties. The nanoscale structure and unique physicochemical properties of graphene enable it to effectively inhibit the growth and reproduction of bacteria, which helps to improve the antibacterial effect of the coolant. To further optimize the performance of graphene nanofluids in the coolant, polyethylene glycol is added as a dispersant. Polyethylene glycol can significantly improve the dispersibility of graphene oxide in the solution, ensuring the uniform distribution of graphene nanofluids in the coolant, thereby improving its thermal conduction efficiency. In addition, the addition of phosphate esters further enhances the stability of graphene nanofluids. Phosphate esters are adsorbed on the surface or inside of graphene oxide through physical or chemical actions, acting as surfactants or stabilizers to effectively prevent the agglomeration of modified graphene nanofluids. At the same time, phosphate esters also have the effect of rust prevention and corrosion inhibition, and can provide additional protection for metal materials in water-soluble coolants, extending the service life of equipment.

[0024] Advantages of the present invention:

[0025] (1) Using castor oil blended with tall oil and naphthenic base oil as the main components of the environmentally friendly composite oil, castor oil has good antioxidant, lubricating and antibacterial properties, effectively extending the service life of the coolant and preventing contamination during use; the protective film formed by tall oil and the stability of naphthenic base oil further ensure that the metal components of the cooling system are protected from corrosion and rust, while improving the durability and reliability of the coolant. The addition of vanillyl alcohol further promotes the antibacterial properties of castor oil. Emulsifier OP-10 ensures the stable combination of the oil phase and the water phase, promoting the storage stability of the coolant.

[0026] (2) Utilizing the high thermal conductivity and thermal diffusivity of graphene nanofluids to significantly improve the thermal conversion efficiency of the coolant and achieve rapid cooling; compared with traditional coolants, graphene nanofluids are more environmentally friendly and sustainable, conforming to the concept of green chemistry; at the same time, the antibacterial properties of graphene effectively inhibit bacterial growth and improve the antibacterial effect. Adding polyethylene glycol as a dispersant ensures the uniform distribution of graphene nanofluids and further improves the thermal conduction efficiency. The addition of phosphate esters enhances the stability, preventing the agglomeration of graphene nanofluids, and phosphate esters can also promote the rust prevention and corrosion inhibition functions of the coolant.

[0027] (3) Mix the environmentally friendly composite oil, modified graphene nanofluid and the remaining additives in a certain proportion to prepare a water-soluble coolant. Compared with traditional coolants, a large number of green and environmentally friendly materials are used in the formulation and material modification process of the present invention, ensuring the ecological friendliness of the entire production and use cycle. The prepared water-soluble coolant exhibits the basic properties of high-efficiency cooling and lubrication, and also has good antibacterial effects. Detailed implementation manners

[0028] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following, in combination with embodiments, details the specific implementation manners, structures, features and their effects according to the present invention as follows.

[0029] In the embodiments and comparative examples of the present invention:

[0030] Castor oil: Purchased from Changsha West Chemical Industry Co., Ltd.

[0031] Tall oil: Purchased from Shanghai Baoyang Baoxin Biotechnology Co., Ltd.

[0032] Naphthenic base oil: Purchased from Shanghai Baoyang Baoxin Biotechnology Co., Ltd.

[0033] Vanillyl alcohol: Purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd.

[0034] Emulsifier OP-10: Purchased from Pande (Shanghai) International Trading Co., Ltd.

[0035] Graphene oxide: Purchased from Anhui Kerun Nano Technology Co., Ltd.

[0036] Polyethylene glycol: Purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0037] Phosphate ester: Purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd.

[0038] Dicyclohexylamine: Purchased from Huansheng Meisen Pharmaceutical Technology (Shandong) Co., Ltd.

[0039] Fatty alcohol polyoxyethylene ether: Purchased from Shandong Xinheng Chemical Co., Ltd.

[0040] Ethylene glycol monobutyl ether: Purchased from Jinan Chuangshi Chemical Industry Co., Ltd.

[0041] Triethanolamine: Purchased from Shandong Bond Chemical Co., Ltd.

[0042] Alcohol ether carboxylic acid: Purchased from Shanghai Jiadel Chemical Technology Co., Ltd.

[0043] Dodecanedioic acid: Purchased from Hangzhou Shi'an Chemical Co., Ltd.

[0044] Benzotriazole: Purchased from Nantong BOTAO Chemical Industry Co., Ltd.

[0045] Silicone defoamer: purchased from Jinan Longcheng Silicone Co., Ltd.

[0046] Example 1

[0047] An environmentally friendly antibacterial water-soluble coolant, the formula 1 of the water-soluble coolant is as follows, by weight percentage, 40% of environmentally friendly composite oil, 7% of dicyclohexylamine, 4.5% of fatty alcohol polyoxyethylene ether, 4% of modified graphene nanofluid, 3% of ethylene glycol monobutyl ether, 0.6% of triethanolamine, 0.9% of AMP95 special amine, 1% of alcohol ether carboxylic acid, 0.5% of dodecanedioic acid, 0.3% of benzotriazole, 0.2% of silicone defoamer, and the balance is deionized water.

[0048] Among them, the preparation method of the environmentally friendly composite oil is as follows.

[0049] S1-1: Put a mixture of 25 parts by weight of castor oil and tall oil, and the mass ratio of castor oil to tall oil in the mixture is 2:1, at a temperature of 45°C and stir at a speed of 650 r / min for 30 min, add 30 parts by weight of naphthenic base oil, raise the speed to 850 r / min and continue to stir at 45°C for 30 min to obtain a mixed oil.

[0050] S1-2: Add 4 parts by weight of vanillyl alcohol to 55 parts by weight of absolute ethanol, ultrasonicate for 30 min, add 0.5 part by weight of emulsifier OP-10, continue ultrasonication for 10 min, then add the mixed oil, and stir at a speed of 800 r / min at 60°C for 1 h to obtain the environmentally friendly composite oil.

[0051] As a preferred technical solution of the present invention, the preparation method of the modified graphene nanofluid is as follows.

[0052] S2-1: Put graphene oxide in a ball mill and ball mill for 1.5 h, the ball mill speed is 250 r / min, the ball milling is carried out under the protection of high-purity nitrogen, then add 12 parts by weight of the ball-milled graphene oxide to 100 parts by weight of absolute ethanol, ultrasonicate at 65°C for 2.5 h, the ultrasonic power is 9 kW, and then place it in a high-speed centrifuge and centrifuge for 15 min, the high-speed centrifuge speed is set to 9000 r / min to obtain solution A.

[0053] S2-2: Add 8 parts by weight of polyethylene glycol to solution A, stir at a speed of 700 r / min at 50°C for 1.5 h, then add phosphate ester, and the addition amount of phosphate ester is 4% of the mass of solution A, raise the temperature to 80°C and stir at a speed of 650 r / min for 1.5 h to obtain the modified graphene nanofluid.

[0054] A preparation method of an environmentally friendly antibacterial water-soluble coolant, the specific steps of the preparation method are as follows.

[0055] Mix the environmentally friendly composite oil, dicyclohexylamine, fatty alcohol polyoxyethylene ether, modified graphene nanofluid, ethylene glycol monobutyl ether, triethanolamine, AMP95 special amine, alcohol ether carboxylic acid, dodecanedioic acid, benzotriazole, silicone defoamer and deionized water according to the ratio of Formula 1, homogenize at 45°C for 1.5 h, and then let it stand at room temperature for 10 h to obtain the environmentally friendly antibacterial water-soluble coolant.

[0056] Example 1

[0057] An environmentally friendly antibacterial water-soluble coolant, and the formula 2 of the water-soluble coolant is as follows, by weight percentage: 30% of environmentally friendly composite oil, 6% of dicyclohexylamine, 4% of fatty alcohol polyoxyethylene ether, 3% of modified graphene nanofluid, 2.5% of ethylene glycol monobutyl ether, 0.5% of triethanolamine, 0.5% of AMP95 special amine, 0.8% of alcohol ether carboxylic acid, 0.4% of dodecanedioic acid, 0.2% of benzotriazole, 0.1% of silicone defoamer, and the balance is deionized water.

[0058] Among them, the preparation method of the environmentally friendly composite oil is as follows.

[0059] S1-1: Place a mixture of 20 parts by weight of castor oil and tall oil, with the mass ratio of castor oil to tall oil in the mixture being 1:1, at a temperature of 40°C and stir at a speed of 600 r / min for 30 min. Add 30 parts by weight of naphthenic base oil, raise the speed to 800 r / min and continue to stir at 40°C for 30 min to obtain a mixed oil.

[0060] S1-2: Add 3 parts by weight of vanillyl alcohol to 50 parts by weight of absolute ethanol, ultrasonicate for 30 min, add 0.5 part by weight of emulsifier OP-10, continue to ultrasonicate for 10 min, then add the mixed oil, and stir at a speed of 750 r / min at 60°C for 1 h to obtain the environmentally friendly composite oil.

[0061] As a preferred technical solution of the present invention, the preparation method of the modified graphene nanofluid is as follows.

[0062] S2-1: Place graphene oxide in a ball mill and ball mill for 1.5 h at a ball mill speed of 200 r / min. The ball milling is carried out under the protection of high-purity nitrogen. Then add 10 parts by weight of the ball-milled graphene oxide to 100 parts by weight of absolute ethanol, ultrasonicate at 60°C for 2 h, with an ultrasonic power of 8 kW, and then place it in a high-speed centrifuge and centrifuge for 10 min. The speed of the high-speed centrifuge is set at 8000 r / min to obtain solution A.

[0063] S2-2: Add 5 parts by weight of polyethylene glycol to Solution A, stir at a speed of 650 r / min at 45 °C for 1 h, then add phosphate ester. The addition amount of phosphate ester is 3% of the mass of Solution A. Raise the temperature to 80 °C and stir at a speed of 600 r / min for 1.5 h to obtain the modified graphene nanofluid.

[0064] A preparation method of an environmentally friendly antibacterial water-soluble coolant. The specific steps of the preparation method are as follows.

[0065] Mix environmentally friendly composite oil, dicyclohexylamine, fatty alcohol polyoxyethylene ether, modified graphene nanofluid, ethylene glycol monobutyl ether, triethanolamine, AMP95 special amine, alcohol ether carboxylic acid, dodecanedioic acid, benzotriazole, silicone defoamer and deionized water according to the ratio of Formula 2, homogenize at 40 °C for 1 h, and then let it stand at room temperature for 8 h to obtain the environmentally friendly antibacterial water-soluble coolant.

[0066] Example 3

[0067] An environmentally friendly antibacterial water-soluble coolant. The formula 3 of the water-soluble coolant is as follows. By weight percentage, environmentally friendly composite oil is 50%, dicyclohexylamine is 8%, fatty alcohol polyoxyethylene ether is 5%, modified graphene nanofluid is 5%, ethylene glycol monobutyl ether is 3.5%, triethanolamine is 1%, AMP95 special amine is 1%, alcohol ether carboxylic acid is 1.2%, dodecanedioic acid is 0.6%, benzotriazole is 0.4%, silicone defoamer is 0.3%, and the balance is deionized water.

[0068] Among them, the preparation method of the environmentally friendly composite oil is as follows.

[0069] S1-1: Place a mixture of 30 parts by weight of castor oil and tall oil, where the mass ratio of castor oil to tall oil in the mixture is 3:1, at a temperature of 50 °C and stir at a speed of 700 r / min for 30 min. Add 30 parts by weight of naphthenic base oil, raise the speed to 900 r / min and continue to stir at 50 °C for 30 min to obtain a mixed oil.

[0070] S1-2: Add 5 parts by weight of vanillyl alcohol to 60 parts by weight of absolute ethanol, ultrasonicate for 30 min, add 0.5 part by weight of emulsifier OP-10, continue to ultrasonicate for 10 min, then add the mixed oil, and stir at a speed of 850 r / min at 60 °C for 1 h to obtain the environmentally friendly composite oil.

[0071] As a preferred technical solution of the present invention, the preparation method of the modified graphene nanofluid is as follows.

[0072] S2-1: Place the graphene oxide in a ball mill and mill it for 1.5 h at a rotation speed of 300 r / min. The ball milling is carried out under the protection of high-purity nitrogen. Subsequently, add 15 parts by weight of the milled graphene oxide to 100 parts by weight of absolute ethanol, ultrasonicate it at 70 °C for 3 h with an ultrasonic power of 10 kW, and then centrifuge it in a high-speed centrifuge for 20 min with the rotation speed of the high-speed centrifuge set at 10,000 r / min to obtain solution A;

[0073] S2-2: Add 10 parts by weight of polyethylene glycol to solution A, stir it at a rotation speed of 750 r / min at 55 °C for 2 h, and then add phosphate ester. The addition amount of the phosphate ester is 5% of the mass of solution A. Raise the temperature to 80 °C and stir it at a rotation speed of 700 r / min for 1.5 h to obtain the modified graphene nanofluid.

[0074] A preparation method of an environmentally friendly antibacterial water-soluble coolant, the specific steps of the preparation method are as follows,

[0075] Mix the environmentally friendly composite oil, dicyclohexylamine, fatty alcohol polyoxyethylene ether, modified graphene nanofluid, ethylene glycol monobutyl ether, triethanolamine, AMP95 special amine, alcohol ether carboxylic acid, dodecanedioic acid, benzotriazole, organosilicon defoamer and deionized water according to the ratio of formulation 3, homogenize it at 50 °C for 2 h, and then place it at room temperature and let it stand for 12 h to obtain the environmentally friendly antibacterial water-soluble coolant.

[0076] Comparative example 1

[0077] In the preparation of the environmentally friendly composite oil, castor oil is not added, and the remaining steps are the same as those in Example 1.

[0078] Comparative example 2

[0079] In the preparation of the environmentally friendly composite oil, vanillyl alcohol is not added, and the remaining steps are the same as those in Example 1.

[0080] Comparative example 3

[0081] The modified graphene nanofluid is not added, and the remaining steps are the same as those in Example 1.

[0082] Performance test

[0083] Refer to the GB 15979-2002 standard to measure the antibacterial performance of the water-soluble coolants prepared in the examples and comparative examples. Escherichia coli and Staphylococcus aureus are used as indicator bacteria, and the initial bacterial concentration is 1×10 6 cfu / mL. The culture conditions for Escherichia coli are constant temperature culture at 37 °C for 16 h, and the culture conditions for Staphylococcus aureus are constant temperature culture at 37 °C for 24 h.

[0084] The experimental data are sorted out in the following table,

[0085]

[0086] As can be seen from the data of the examples and comparative examples, the coolant prepared by the present invention has good antibacterial properties.

[0087] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the above-disclosed technical content within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. An environmentally friendly antibacterial water-soluble coolant, characterized in that: The formula of the water-soluble coolant is as follows: by weight percentage, 30% to 50% of environmentally friendly composite oil, 6% to 8% of dicyclohexylamine, 4% to 5% of surfactant, 3% to 5% of modified graphene nanofluid, 2.5% to 3.5% of ethylene glycol butyl ether, 1% to 2% of pH regulating stabilizer, 0.8% to 1.2% of alcohol ether carboxylic acid, 0.4% to 0.6% of dodecane dibasic acid, 0.2% to 0.4% of benzotriazole, 0.1% to 0.3% of organosilicon defoamer, and the balance of deionized water. The preparation method of the environmentally friendly composite oil is as follows: S1-1: a mixture of 20 to 30 parts by weight of castor oil and tall oil is stirred at 40 to 50° C. and 600 to 700 r / min for 30 min, 30 parts by weight of cyclohexane base oil is added, the speed is increased to 800 to 900 r / min, and stirring is continued at 40 to 50° C. for 30 min to obtain a mixed oil; S1-2: Add 3 to 5 parts by weight of vanillin alcohol to 50 to 60 parts by weight of anhydrous ethanol, ultrasonicate for 30 minutes, add 0.5 parts by weight of emulsifier, continue ultrasonicate for 10 minutes, then add mixed oil, stir at 60°C and 750 to 850 r / min for 1 hour to obtain the environmentally friendly composite oil.

2. The environmentally friendly antibacterial water-soluble coolant according to claim 1, characterized in that: The preparation method of the modified graphene nanofluid is as follows: S2-1: The graphene oxide is placed in a ball mill for 1.5 hours, and the ball milling is carried out under the protection of high-purity nitrogen. Then, 10 to 15 parts by weight of the ball-milled graphene oxide are added to 100 parts by weight of anhydrous ethanol, and ultrasonicated at 60 to 70° C. for 2 to 3 hours with an ultrasonic power of 8 to 10 kW. The solution is then placed in a high-speed centrifuge for centrifugation for 10 to 20 minutes to obtain a solution A. S2-2: Add 5 to 10 parts by weight of polyethylene glycol to solution A, stir at 45 to 55° C. and 650 to 750 r / min for 1 to 2 hours, then add phosphate, raise the temperature to 80° C. and stir at 600 to 700 r / min for 1.5 hours to obtain the modified graphene nanofluid.

3. The environmentally friendly antibacterial water-soluble coolant according to claim 1, characterized in that: The pH regulating stabilizer is a mixture of triethanolamine and AMP95 special amine in a mass ratio of 1: (1-2).

4. The environmentally friendly antibacterial water-soluble coolant according to claim 1, characterized in that: The surfactant is one or both of fatty alcohol polyoxyethylene ether and fatty alcohol polyoxyethylene ether sodium sulfate.

5. The environmentally friendly antibacterial water-soluble coolant according to claim 1, characterized in that: The mixture of castor oil and tall oil in S1-1 is mixed in a mass ratio of (1-3):1 between castor oil and tall oil.

6. The environmentally friendly antibacterial water-soluble coolant according to claim 1, characterized in that: The emulsifier in the S1-2 is OP-10.

7. The environmentally friendly antibacterial water-soluble coolant according to claim 2, characterized in that: The ball milling speed in S2-1 is 200-300 r / min.

8. The environmentally friendly antibacterial water-soluble coolant according to claim 2, characterized in that: The speed of the high-speed centrifuge in S2-1 is set to 8000-10000 r / min.

9. The environmentally friendly antibacterial water-soluble coolant according to claim 2, characterized in that: The amount of phosphate added in S2-2 is 3% to 5% of the mass of solution A.

10. A method for preparing the environmentally friendly antibacterial water-soluble coolant according to any one of claims 1 to 9, characterized in that: The specific steps of the preparation method are as follows: Environmentally friendly composite oil, dicyclohexylamine, surfactant, modified graphene nanofluid, ethylene glycol butyl ether, pH adjusting stabilizer, alcohol ether carboxylic acid, dodecane dibasic acid, benzotriazole, silicone defoamer and deionized water are mixed according to the formula ratio, homogenized at 40-50° C. for 1-2 hours, and then placed at room temperature for 8-12 hours to obtain the environmentally friendly antibacterial water-soluble coolant.

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