Emulsion cutting fluid taking plant extract as bactericide and preparation method thereof

Abstract

The invention discloses an emulsified cutting fluid using a plant extract as a bactericide. The emulsified cutting fluid is prepared from the following raw materials in parts by weight: 15-28 parts of base oil 1, 25-28 parts of base oil 2, 8-16 parts of an oil-soluble antirust agent, 10-19 parts of an emulsifier, 0.0-0.6 part of an antioxidant, 2-4 parts of an emulsion stabilizer and 3-5 parts of the plant extract bactericide, the base oil 1 is 150SN or transformer oil, the base oil 2 is naphthenic mineral oil, and the plant extract bactericide is a mixture of malus hupehensis extract, wolf thorn extract and melia azedarach extract. The special plant extract bactericide can effectively inhibit bacteria, fungi and anaerobic bacteria, has a broad-spectrum bactericidal effect, has good compatibility and emulsification stability, does not produce layering, turbidity and foam, does not destroy the uniformity and lubrication performance of the cutting fluid, can significantly reduce the skin irritation risk when workers contact the cutting fluid, and has a good application prospect. And the biodegradability is good, the biodegradability is easy to decompose by microorganisms in the natural environment, and the goal of'zero emission 'is favorably realized.

Description

Technical Field

[0001] This invention relates to an industrial processing fluid, specifically to an emulsified cutting fluid using plant extracts as bactericides and its preparation method. Background Technology

[0002] Metalworking fluids are highly susceptible to bacterial, fungal, and yeast growth during use, leading to foul odors, deterioration, and even equipment corrosion. Choosing the right bactericide is crucial for extending the lifespan of cutting fluids. Traditional bactericides are mostly organic synthetic chemicals, which, while pursuing high-efficiency and broad-spectrum sterilization, often come with negative impacts on the environment, equipment, and human health. Many traditional bactericides contain formaldehyde-releasing groups or organic halogens, exhibiting significant toxicity and irritation. Some bactericides (such as triazines) may release formaldehyde, irritating the skin and causing allergies in workers. Chlorine- or phosphorus-containing bactericides may pollute water bodies, and long-term use of a single bactericide may lead to microbial resistance, rendering the bactericide ineffective. Furthermore, some components are highly volatile, potentially causing respiratory irritation, and waste disposal is costly. In addition, the addition of traditional bactericides is often a double-edged sword, sacrificing other key performance characteristics in the pursuit of bacterial elimination. For example, some bactericides can disrupt the alkalinity balance of cutting fluids, causing a drop in pH and leading to corrosion problems. High concentrations of bactericides may cause oil-water separation in cutting fluids, disrupting the emulsion state. Compatible bactericides may directly corrode the surface of machine tools or workpieces, and so on.

[0003] Therefore, it is necessary to address the issues of cutting fluid contamination and environmental impact, as well as its compatibility with bactericides. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide an emulsified cutting fluid with plant extracts as bactericides and its preparation method. The emulsified cutting fluid has a long-lasting effect, can effectively avoid the problem of high-temperature spoilage and deterioration, and is mild, non-irritating, and environmentally friendly.

[0005] This invention discloses an emulsified cutting fluid using plant extracts as bactericides. The emulsion raw materials comprise the following components by weight: 15-28 parts of base 1, 25-28 parts of base oil 2, 8-16 parts of oil-soluble rust inhibitor, 10-19 parts of emulsifier, 0.0-0.6 parts of antioxidant, 2-4 parts of emulsion stabilizer, and 3-5 parts of plant extract bactericide. The base 1 is 150SN or transformer oil, the base oil 2 is a naphthenic mineral, and the plant extract bactericide is a mixture of extracts from Malus halliana, hornwort, and neem.

[0006] Furthermore, according to claim 1, the plant-based bactericide for metalworking fluid is characterized in that: the emulsion raw material comprises the following components by weight: 20 parts base 1, 26 parts base oil 2, 12 parts oil-soluble rust inhibitor, 15 parts emulsifier, 0.2 parts antioxidant, 3 parts emulsion stabilizer, and 4 parts plant extract bactericide.

[0007] Furthermore, by mass ratio, the extracts of *Malus hupehensis*, *Hypericum perforatum*, and *Melia azedarach* are 1:2-4:2-4.

[0008] Furthermore, the *Malus hupehensis* extract is an extract of the old leaves of *Malus hupehensis*, and the *Melia azedarach* extract is an extract of the bark of the *Melia azedarach*.

[0009] Furthermore, the preparation of the plant extracts includes the following steps: drying and pulverizing the extracts of Malus hupehensis, hornwort, and chinaberry, then adding them to the extraction solution for extraction at room temperature, filtering and taking the supernatant, adjusting its pH value to alkaline, and obtaining Malus hupehensis extract, hornwort extract, and chinaberry extract respectively.

[0010] Furthermore, the extract is one or a mixture of two or more of the following: ethanol, glycerol, ethanolamine, diethylene glycol butyl ether, ethylene glycol butyl ether, diethanol n-butyl ether, and triethanol monobutyl ether.

[0011] Furthermore, the oil-soluble rust inhibitor is one or a mixture of two or more of the following: medium-alkalinity calcium sulfonate, fatty acid oleic acid ester, synthetic petroleum sulfonate sodium, RC4295, T746, and T706.

[0012] Furthermore, the emulsifier is one or a mixture of two or more of the following: petroleum sulfonic acid T702, sodium heavy alkylbenzene sulfonate, sodium fatty acid soap, potassium fatty acid soap, fatty acid amine salt, fatty acid amide, sorbitol oleate, and Pingpingjia O-10.

[0013] Furthermore, the antioxidant is T501, and the emulsifying stabilizer is one or a mixture of two or more of the following: 20% potassium hydroxide, 20% sodium hydroxide, ammonia, ethanolamine, methanol, ethanol, glycerol, ethylene glycol butyl ether, diethylene glycol butyl ether, and ethylene glycol ether.

[0014] This invention also discloses a method for preparing an emulsified cutting fluid using plant extracts as bactericides, comprising the following steps: mixing base oil 1 and base oil 2 and heating to a temperature of 120-140°C, adding an oil-soluble rust inhibitor and stirring to dehydrate, then cooling to 70-90°C and adding an emulsifier and stirring until fully dissolved, then cooling to 50-60°C and adding an antioxidant and stirring evenly, finally adding an emulsion stabilizer and stirring evenly, then cooling to 20-40°C and adding a plant extract bactericide.

[0015] The beneficial effects of this invention are as follows: The emulsified cutting fluid with plant extracts as bactericides and its preparation method of this invention use specific plant extract bactericides, which can effectively inhibit bacteria, fungi and anaerobic bacteria, have a broad-spectrum bactericidal effect, and have good compatibility. It has good emulsification stability, does not produce stratification, turbidity and foam, and does not damage the uniformity and lubrication performance of the cutting fluid. At the same time, it can significantly reduce the risk of skin irritation when workers come into contact with it, and has good biodegradability. It is easily decomposed by microorganisms in the natural environment, which helps to achieve the goal of "zero emissions". Detailed Implementation

[0016] To better understand the present invention, the following embodiments are further illustrations of the present invention, but the content of the present invention is not limited to the following embodiments.

[0017] Unless otherwise specified, the experimental methods used in the embodiments are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0018] This embodiment describes an emulsified cutting fluid using plant extracts as a bactericide. The emulsion raw materials, by weight, include the following components: 15-28 parts base 1, 25-28 parts base oil 2, 8-16 parts oil-soluble rust inhibitor, 10-19 parts emulsifier, 0.0-0.6 parts antioxidant, 2-4 parts emulsion stabilizer, and 3-5 parts plant extract bactericide. Base 1 is 150SN or transformer oil, base oil 2 is a naphthenic mineral, and the plant extract bactericide is a mixture of extracts from *Malus spectabilis*, *Hypericum perforatum*, and *Melia azedarach*. Base oil 2 readily combines with surfactants to form a stable emulsion, ensuring uniform dispersion of the cutting fluid in water and preventing demulsification. Base oil 2 also acts as a blending component, enhancing the overall service life of the cutting fluid system. This process prevents oil oxidation and deterioration. Using two base oils in combination effectively balances the oil's low-temperature fluidity and antioxidant stability. The neem extract, primarily containing azadirachtin and terpenes, possesses strong insecticidal and antibacterial properties. As a broad-spectrum bactericide, it effectively inhibits common putrefactive bacteria such as *Pseudomonas aeruginosa*. The *Malus hupehensis* extract, containing flavonoids and phenolic acids, disrupts bacterial cell membrane permeability. As a broad-spectrum adjuvant, it works synergistically with *Hylocereus undatus* extract and neem extract, primarily targeting Gram-positive bacteria (such as *Staphylococcus aureus*). *Hylocereus undatus* extract, mainly containing polysaccharides, saponins, and organic acids, provides long-lasting biological stability and directly inhibits bacteria. Synergistically, it works with *Malus hupehensis* extract and neem extract to prevent fungal (mold) colonization in the coolant. The core advantage of introducing *Malus hupehensis* extract, *Hylocereus undatus* extract, and neem extract into the cutting fluid lies in overcoming microbial resistance. Single bactericides can easily lead to the development of resistance genes in microorganisms, while mixed use can "encircle and suppress" microorganisms through different targets, with broad-spectrum effects due to the simultaneous attack on bacterial cell walls, membranes, and metabolic pathways. In the emulsified cutting fluid of this invention, because the extract contains alcohol and alcohol ether complex components, their hydrophilic and lipophilic groups work synergistically with emulsifiers to enhance the solution of the base oil in the emulsified cutting fluid being difficult to dissolve in water and difficult to balance. The alcohol and alcohol ethers, through the intermolecular forces of hydrogen bonds, promote the phase balance and moisture stability of the aqueous and oil phases of the emulsion, effectively inhibiting the stratification of the emulsified cutting fluid during long-term storage and the separation of oil and soap in the working fluid mixed with water. At the same time, it reduces the dependence of the emulsion on co-emulsifiers, coupling agents, and chelating additives, and can reduce or even avoid the use of co-emulsifiers and chelates in the emulsion formulation.

[0019] Furthermore, the plant extract bactericide used in this invention dissolves well in the base oil of the cutting fluid, and the base oil prevents the heat-sensitive components in the plant extract from decomposing and failing under high-temperature processing conditions. The plant extract bactericide, possessing natural surfactant properties, helps the base oil better adsorb onto the metal surface to form a protective film. Moreover, the plant extract bactericide does not react with oil-soluble rust inhibitors to form precipitation. The combination of the plant extract bactericide and the oil-soluble rust inhibitor achieves both "environmental friendliness" and "long-lasting protection" through the broad-spectrum antibacterial properties of the plant components and the metal interface protection capability of the oil-soluble rust inhibitor. The oil film formed by the oil-soluble rust inhibitor acts as a physical barrier, helping the plant extract bactericide maintain emulsion stability. In this invention, the emulsifier is not merely a medium for mixing oil and water, but a crucial "bridge" determining the effectiveness of the plant bactericide components. The synergistic effect of the two, with the emulsifier forming a gel... The plant extracts, using a bundle or microcapsule structure, encapsulate and uniformly disperse unstable plant-based bactericides in the aqueous phase, preventing sedimentation or floating. Simultaneously, they guide the plant-based bactericides to adsorb onto the bacterial cell membrane surface, improving contact efficiency. Meanwhile, the emulsifier disrupts the hydrophobic layer of the microbial cell membrane, facilitating the entry of the plant-based bactericides into the cell and producing a synergistic antibacterial effect. Furthermore, the plant-based bactericides and emulsifiers work together. The plant extracts of this invention possess both moisturizing and anti-inflammatory properties, not only killing bacteria but also repairing micro-damage to metal surfaces caused by friction, achieving dual protection of "corrosion prevention + rust prevention." In addition, the plant extracts provide abundant phenolic hydroxyl groups, directly capturing oxygen free radicals and forming an "antioxidant network" with synthetic antioxidants, covering the lipid-soluble and water-soluble interfaces, protecting emulsified oil droplets from oxidative degradation, and maintaining the stability of the working fluid. In this invention, because the plant extracts have antioxidant functions, they can replace or partially replace antioxidants.

[0020] In a preferred embodiment, the emulsion raw material comprises the following components by weight: 20 parts base 1, 26 parts base oil 2, 12 parts oil-soluble rust inhibitor, 15 parts emulsifier, 0.2 parts antioxidant, 3 parts emulsion stabilizer, and 4 parts plant extract bactericide.

[0021] Based on the interaction of extracts from *Malus hupehensis*, *Hypericum perforatum*, and *Melia azedarach* in metalworking fluids, a preferred mass ratio is *Malus hupehensis* extract: *Hypericum perforatum* extract: *Melia azedarach* extract = 1:2.5:2.5; the bactericide in this embodiment exhibits the best effect in metalworking fluids. Furthermore, it is preferred that the *Malus hupehensis* extract is an extract from the old leaves of *Malus hupehensis*, and the *Melia azedarach* extract is an extract from the bark of *Melia azedarach*.

[0022] Preferably, the oil-soluble rust inhibitor is one or a mixture of two or more of the following: medium-alkalinity calcium sulfonate, fatty acid oleate, synthetic petroleum sulfonate sodium, RC4295, T746, and T706; the emulsifier is one or a mixture of two or more of the following: petroleum sulfonate T702, sodium heavy alkylbenzene sulfonate, sodium fatty acid soap, potassium fatty acid soap, fatty acid amine salt, fatty acid amide, sorbitan oleate, and Pingpingjia O-10; the antioxidant is T501; and the emulsion stabilizer is one or a mixture of two or more of the following: 20% potassium hydroxide, 20% sodium hydroxide, ammonia, ethanolamine, methanol, ethanol, glycerol, ethylene glycol butyl ether, diethylene glycol butyl ether, and ethylene glycol ether. Medium-alkalinity calcium sulfonate (usually referring to synthetic calcium sulfonate with a total alkalinity (TBN) between 150 and 1250 mgKOH / g) is an important metal detergent and surfactant. It falls in the middle range between "low alkalinity" and "high alkalinity". RC4295, or Additin® RC4295, is a high-performance oil-soluble rust inhibitor produced by LANXESS Rhein Chemie. T746 is a classic oil-soluble, ashless rust inhibitor, chemically named dodecenylsuccinic acid. T706's core chemical component is benzotriazole (BTA), a highly efficient, low-toxicity corrosion inhibitor for copper and copper alloys, and also exhibits good rust prevention properties for ferrous metals (such as steel). Sodium petroleum sulfonate (T702) is a highly efficient additive widely used in metal processing. It is not only an excellent emulsifier but also possesses outstanding rust prevention (corrosion inhibition) properties due to its unique molecular structure. Emulsifier O-10, chemically named Cetyl Stearyl Alcohol Polyoxyethylene Ether, is a widely used nonionic surfactant. It is a product formed by the condensation of fatty alcohols and ethylene oxide.

[0023] In this embodiment, the preparation of the plant extracts includes the following steps: The extracts of *Malus hupehensis*, *Hypericum perforatum*, and *Melia azedarach* are dried, pulverized, and then extracted separately with an extraction solution at room temperature. After filtration, the supernatant is collected, and its pH is adjusted to alkaline to obtain *Malus hupehensis* extract, *Hypericum perforatum* extract, and *Melia azedarach* extract, respectively. Extraction is superior to decoction. Decoction is difficult to destroy the hard plant tissues, and prolonged high-temperature heating may damage heat-sensitive components. Extraction significantly improves efficiency and retains components. The extraction solution is one or a mixture of two or more of ethanol, glycerol, ethanolamine, diethylene glycol butyl ether, ethylene glycol butyl ether, diethanol n-butyl ether, and triethanol monobutyl ether.

[0024] This embodiment also discloses a method for preparing an emulsified cutting fluid using plant extracts as a bactericide, comprising the following steps: mixing base oil 1 and base oil 2 and heating to 120-140℃, adding an oil-soluble rust inhibitor and stirring to dehydrate, then cooling to 70-90℃ and adding an emulsifier and stirring until fully dissolved, then cooling to 50-60℃ and adding an antioxidant and stirring evenly, finally adding an emulsion stabilizer and stirring evenly, then cooling to 20-40℃ and adding the plant extract bactericide. The preparation method is simple and easy to operate.

[0025] Example 1

[0026] This embodiment of the emulsified cutting fluid using plant extracts as bactericides comprises the following components by weight: 15 parts base 1, 25 parts base oil 2, 8 parts oil-soluble rust inhibitor, 10 parts emulsifier, 0.01 parts antioxidant (T501), 2 parts emulsion stabilizer, and 3 parts plant extract bactericide. Base 1 is 150SN or transformer oil, base oil 2 is a naphthenic mineral, and the plant extract bactericide is a mixture of extracts from *Malus hupehensis*, *Hypericum perforatum*, and *Melia azedarach*. The mass ratio of *Malus hupehensis* extract to *Hypericum perforatum* extract to *Melia azedarach* extract is 1:2:2.

[0027] In this embodiment, the oil-soluble rust inhibitor is medium-alkalinity calcium sulfonate. Replacing the medium-alkalinity calcium sulfonate in this embodiment with one of fatty acid oleic acid ester, synthetic petroleum sulfonate sodium, RC4295, T746, or T706, or with a mixture of medium-alkalinity calcium sulfonate and fatty acid oleic acid ester, synthetic petroleum sulfonate sodium, RC4295, T746, or T706, can achieve the purpose of this invention.

[0028] In this embodiment, the emulsifier is petroleum sulfonic acid T702. Replacing petroleum sulfonic acid T702 in this embodiment with one of sodium heavy alkylbenzene sulfonate, sodium fatty acid soap, potassium fatty acid soap, fatty acid amine salt, fatty acid amide, sorbitol oleate, or Pingpingjia O-10, or a mixture of petroleum sulfonic acid T702 and sodium heavy alkylbenzene sulfonate, sodium fatty acid soap, potassium fatty acid soap, fatty acid amine salt, fatty acid amide, sorbitol oleate, and Pingpingjia O-10, can achieve the purpose of this invention.

[0029] In this embodiment, the emulsifying stabilizer is 20% potassium hydroxide. Replacing the 20% potassium hydroxide in this embodiment with one of the following: 20% sodium hydroxide, ammonia, ethanolamine, methanol, ethanol, glycerol, ethylene glycol butyl ether, diethylene glycol butyl ether, or ethylene glycol ether, or a mixture of 20% potassium hydroxide and 20% sodium hydroxide, ammonia, ethanolamine, methanol, ethanol, glycerol, ethylene glycol butyl ether, diethylene glycol butyl ether, or ethylene glycol ether, can achieve the purpose of this invention.

[0030] Preparation method of plant extract bactericide: The extracts of *Malus hupehensis*, *Hypericum perforatum*, and *Melia azedarach* were dried, pulverized, and sieved using a 0.8 mm sieve. 30% of the base solution (water) was added to the reaction vessel according to a set weight percentage. The temperature was kept constant at 40°C. Then, the plant powder was added and thoroughly soaked, followed by stirring. The temperature was then lowered to 25°C. While stirring, the extraction liquid (ethanol:ethylene glycol butyl ether: diethylene glycol butyl ether = 5:0.5:1 by mass percentage) was sprayed in. The remaining 70% of the base solution (water) was then added. After filtration, pressure filtration, three sedimentation processes, and centrifugation to remove impurities, the supernatant was used to adjust the pH to 8 with 20% potassium hydroxide. This yielded the extracts of *Malus hupehensis*, *Hypericum perforatum*, and *Melia azedarach*. The filtration, pressure filtration, three sedimentation processes, and centrifugation used in this embodiment and the following embodiments are conventional techniques and will not be described in detail here.

[0031] The preparation method of emulsified cutting fluid includes the following steps: mixing base oil 1 and base oil 2 and heating to 120°C, adding oil-soluble rust inhibitor and stirring to dehydrate, then cooling to 70°C and adding emulsifier and stirring until fully dissolved, then cooling to 50°C and adding antioxidant and stirring evenly, finally adding emulsifying stabilizer and stirring evenly, then cooling to 20°C and adding plant extract bactericide.

[0032] Example 2

[0033] This embodiment of the emulsified cutting fluid using plant extracts as bactericides comprises the following components by weight: 28 parts base 1, 28 parts base oil 2, 16 parts oil-soluble rust inhibitor, 19 parts emulsifier, 0.6 parts antioxidant (T501), 4 parts emulsion stabilizer, and 5 parts plant extract bactericide. Base 1 is 150SN or transformer oil, base oil 2 is a naphthenic mineral, and the plant extract bactericide is a mixture of *Malus spectabilis* extract, *Hypericum esculentum* extract, and *Melia azedarach* extract. The mass ratio of *Malus spectabilis* extract: *Hypericum esculentum* extract: *Melia azedarach* extract = 1:4:4.

[0034] In this embodiment, the oil-soluble rust inhibitor is synthetic petroleum sulfonate sodium. Replacing the synthetic petroleum sulfonate sodium in this embodiment with one of fatty acid oleate, medium-alkalinity calcium sulfonate, RC4295, T746, and T706, or with a mixture of fatty acid oleate, medium-alkalinity calcium sulfonate, synthetic petroleum sulfonate sodium, RC4295, T746, and T706, can achieve the purpose of this invention.

[0035] In this embodiment, the emulsifier is sodium alkylbenzene sulfonate. Replacing the sodium alkylbenzene sulfonate in this embodiment with one of petroleum sulfonic acid T702, sodium fatty acid soap, potassium fatty acid soap, fatty acid amine salt, fatty acid amide, sorbitol oleate, or Pingpingjia O-10, or with a mixture of sodium alkylbenzene sulfonate and petroleum sulfonic acid T702, sodium fatty acid soap, potassium fatty acid soap, fatty acid amine salt, fatty acid amide, sorbitol oleate, and Pingpingjia O-10, can achieve the purpose of this invention.

[0036] In this embodiment, the emulsifying stabilizer is 20% sodium hydroxide. Replacing the 20% sodium hydroxide in this embodiment with one of the following: 20% potassium hydroxide, ammonia, ethanolamine, methanol, ethanol, glycerol, ethylene glycol butyl ether, diethylene glycol butyl ether, or ethylene glycol ether, or a mixture of 20% sodium hydroxide and 20% potassium hydroxide, ammonia, ethanolamine, methanol, ethanol, glycerol, ethylene glycol butyl ether, diethylene glycol butyl ether, or ethylene glycol ether, can achieve the objective of this invention.

[0037] Preparation method of plant extract bactericide: The extracts of *Malus hupehensis*, *Hypericum perforatum*, and *Melia azedarach* were dried, pulverized, and sieved using a 0.8 mm sieve. 30% of the base solution (water) was added to the reaction vessel according to the set weight percentage. The temperature was kept constant at 40°C. Then, the plant powder was added and thoroughly soaked and stirred. The temperature was then lowered to 30°C. While stirring, the extraction liquid (ethanol:ethylene glycol butyl ether: diethylene glycol butyl ether = 5:0.5:1 by mass percentage) was sprayed in. Then, the remaining 70% of the base solution (water) was added. After filtration, pressure filtration, three sedimentation processes, and centrifugation to remove impurities, the supernatant was taken and the pH was adjusted to 9 using 20% ​​potassium hydroxide. Extracts of *Malus hupehensis*, *Hypericum perforatum*, and *Melia azedarach* were obtained respectively.

[0038] The preparation method of emulsified cutting fluid includes the following steps: mixing base oil 1 and base oil 2 and heating to a temperature of 140°C, adding an oil-soluble rust inhibitor and stirring to dehydrate, then cooling to 90°C and adding an emulsifier and stirring until fully dissolved, then cooling to 60°C and adding an antioxidant and stirring evenly, finally adding an emulsifying stabilizer and stirring evenly, then cooling to 40°C and adding a plant extract bactericide.

[0039] Example 3

[0040] This embodiment of the emulsified cutting fluid using plant extracts as bactericides comprises the following components by weight: 158 parts base 1, 28 parts base oil 2, 8 parts oil-soluble rust inhibitor, 19 parts emulsifier, 0.05 parts antioxidant (T501), 4 parts emulsion stabilizer, and 3 parts plant extract bactericide. Base 1 is 150SN or transformer oil, base oil 2 is a naphthenic mineral, and the plant extract bactericide is a mixture of *Malus spectabilis* extract, *Hypericum perforatum* extract, and *Melia azedarach* extract. The mass ratio of *Malus spectabilis* extract: *Hypericum perforatum* extract: *Melia azedarach* extract = 1:2.5:3.

[0041] In this embodiment, the oil-soluble rust inhibitor is synthetic petroleum sulfonate sodium. Replacing the synthetic petroleum sulfonate sodium in this embodiment with one of fatty acid oleate, medium-alkalinity calcium sulfonate, RC4295, T746, and T706, or with a mixture of synthetic petroleum sulfonate sodium and fatty acid oleate, medium-alkalinity calcium sulfonate, RC4295, T746, and T706, can achieve the purpose of this invention.

[0042] In this embodiment, the emulsifier is sodium fatty acid soap. Replacing the sodium fatty acid soap in this embodiment with one of sodium alkylbenzene sulfonate, petroleum sulfonate T702, potassium fatty acid soap, fatty acid amine salt, fatty acid amide, sorbitol oleate, or Pingpingjia O-10, or a mixture of sodium fatty acid soap and sodium alkylbenzene sulfonate, petroleum sulfonate T702, potassium fatty acid soap, fatty acid amine salt, fatty acid amide, sorbitol oleate, and Pingpingjia O-10, can achieve the purpose of this invention.

[0043] In this embodiment, the emulsifying stabilizer is ammonia. Replacing the ammonia in this embodiment with one of the following: 20% sodium hydroxide, 20% potassium hydroxide, ethanolamine, methanol, ethanol, glycerol, ethylene glycol butyl ether, diethylene glycol butyl ether, or ethylene glycol ether, or a mixture of ammonia and 20% sodium hydroxide, 20% potassium hydroxide, ethanolamine, methanol, ethanol, glycerol, ethylene glycol butyl ether, diethylene glycol butyl ether, or ethylene glycol ether, can achieve the purpose of this invention.

[0044] Preparation method of plant extract bactericide: The extracts of *Malus hupehensis*, *Hypericum perforatum*, and *Melia azedarach* were dried, pulverized, and sieved using a 0.8 mm sieve. 30% of the base solution (water) was added to the reaction vessel according to the set weight percentage. The temperature was kept constant at 40℃. Then, the plant powder was added and thoroughly soaked and stirred. The temperature was then lowered to 28℃. While stirring, the extraction liquid (ethanol:ethylene glycol butyl ether: diethylene glycol butyl ether = 5:0.5:1 by mass percentage) was sprayed in. Then, the remaining 70% of the base solution (water) was added. After filtration, pressure filtration, three sedimentation processes, and centrifugation to remove impurities, the supernatant was taken and the pH was adjusted to 9.5 using 20% ​​potassium hydroxide. Extracts of *Malus hupehensis*, *Hypericum perforatum*, and *Melia azedarach* were obtained respectively.

[0045] The preparation method of emulsified cutting fluid includes the following steps: mixing base oil 1 and base oil 2 and heating to 130°C, adding oil-soluble rust inhibitor and stirring to dehydrate, then cooling to 78°C and adding emulsifier and stirring until fully dissolved, then cooling to 55°C and adding antioxidant and stirring evenly, finally adding emulsifying stabilizer and stirring evenly, then cooling to 28°C and adding plant extract bactericide.

[0046] Example 4

[0047] This embodiment of the emulsified cutting fluid using plant extracts as bactericides comprises the following components by weight: 28 parts base 1, 26 parts base oil 2, 14 parts oil-soluble rust inhibitor, 12 parts emulsifier, 0.3 parts antioxidant (T501), 3 parts emulsion stabilizer, and 3 parts plant extract bactericide. Base 1 is 150SN or transformer oil, base oil 2 is a naphthenic mineral, and the plant extract bactericide is a mixture of *Malus spectabilis* extract, *Hypericum perforatum* extract, and *Melia azedarach* extract. The mass ratio of *Malus spectabilis* extract: *Hypericum perforatum* extract: *Melia azedarach* extract = 1:3:2.

[0048] In this embodiment, the oil-soluble rust inhibitor is RC4295. Replacing RC4295 in this embodiment with one of fatty acid oleic acid ester, synthetic petroleum sulfonate sodium, medium-alkalinity calcium sulfonate, T746, or T706, or a mixture of RC4295 and fatty acid oleic acid ester, synthetic petroleum sulfonate sodium, medium-alkalinity calcium sulfonate, T746, or T706, can achieve the purpose of this invention.

[0049] In this embodiment, the emulsifier is a fatty acid amine salt. Replacing the fatty acid amine salt in this embodiment with one of sodium alkylbenzene sulfonate, sodium fatty acid soap, potassium fatty acid soap, petroleum sulfonate T702, fatty acid amide, sorbitol oleate, or Pingpingjia O-10, or a mixture of fatty acid amine salt and sodium alkylbenzene sulfonate, sodium fatty acid soap, potassium fatty acid soap, petroleum sulfonate T702, fatty acid amide, sorbitol oleate, and Pingpingjia O-10, can achieve the purpose of this invention.

[0050] In this embodiment, the emulsifying stabilizer is ethanolamine. Replacing the ethanolamine in this embodiment with one of the following: 20% sodium hydroxide, ammonia, 20% potassium hydroxide, methanol, ethanol, glycerol, ethylene glycol butyl ether, diethylene glycol butyl ether, or ethylene glycol ether, or with a mixture of ethanolamine and 20% sodium hydroxide, ammonia, 20% potassium hydroxide, methanol, ethanol, glycerol, ethylene glycol butyl ether, diethylene glycol butyl ether, or ethylene glycol ether, can achieve the objective of this invention.

[0051] Preparation method of plant extract bactericide: The extracts of *Malus hupehensis*, *Hypericum perforatum*, and *Melia azedarach* were dried, pulverized, and sieved using a 0.8 mm sieve. 30% of the base solution (water) was added to the reaction vessel according to the set weight percentage. The temperature was kept constant at 40℃. Then, the plant powder was added and thoroughly soaked and stirred. The temperature was then lowered to 28℃. While stirring, the extraction liquid (ethanol:ethylene glycol butyl ether: diethylene glycol butyl ether = 5:0.5:1 by mass percentage) was sprayed in. Then, the remaining 70% of the base solution (water) was added. After filtration, pressure filtration, three sedimentation processes, and centrifugation to remove impurities, the supernatant was taken and the pH was adjusted to 9.5 using 20% ​​potassium hydroxide. Extracts of *Malus hupehensis*, *Hypericum perforatum*, and *Melia azedarach* were obtained respectively.

[0052] The preparation method of emulsified cutting fluid includes the following steps: mixing base oil 1 and base oil 2 and heating to 135°C, adding oil-soluble rust inhibitor and stirring to dehydrate, then cooling to 85°C and adding emulsifier and stirring until fully dissolved, then cooling to 555°C and adding antioxidant and stirring evenly, finally adding emulsifying stabilizer and stirring evenly, then cooling to 25°C and adding plant extract bactericide.

[0053] Example 5

[0054] This embodiment of the emulsified cutting fluid using plant extracts as bactericides comprises the following components by weight: 20 parts base 1, 28 parts base oil 2, 12 parts oil-soluble rust inhibitor, 15 parts emulsifier, 0.35 parts antioxidant (T501), 2 parts emulsion stabilizer, and 4 parts plant extract bactericide. Base 1 is 150SN or transformer oil, base oil 2 is a naphthenic mineral, and the plant extract bactericide is a mixture of *Malus spectabilis* extract, *Hypericum perforatum* extract, and *Melia azedarach* extract. The mass ratio of *Malus spectabilis* extract: *Hypericum perforatum* extract: *Melia azedarach* extract = 1:2.5:2.5.

[0055] In this embodiment, the oil-soluble rust inhibitor is T706. Replacing T706 in this embodiment with one of fatty acid oleic acid ester, synthetic petroleum sulfonate sodium, RC4295, T746, or medium-alkalinity calcium sulfonate, or with a mixture of T706 and fatty acid oleic acid ester, synthetic petroleum sulfonate sodium, RC4295, T746, or medium-alkalinity calcium sulfonate, can achieve the purpose of this invention.

[0056] In this embodiment, the emulsifier is a fatty acid amide. Replacing the fatty acid amide in this embodiment with one of sodium alkylbenzene sulfonate, sodium fatty acid soap, potassium fatty acid soap, fatty acid amine salt, petroleum sulfonate T702, sorbitol oleate, or Pingpingjia O-10, or a mixture of fatty acid amide and sodium alkylbenzene sulfonate, sodium fatty acid soap, potassium fatty acid soap, fatty acid amine salt, petroleum sulfonate T702, sorbitol oleate, and Pingpingjia O-10, can achieve the purpose of this invention.

[0057] In this embodiment, the emulsifying stabilizer is diethylene glycol butyl ether. Replacing the diethylene glycol butyl ether in this embodiment with one of the following: 20% sodium hydroxide, ammonia, ethanolamine, methanol, ethanol, glycerol, ethylene glycol butyl ether, 20% potassium hydroxide, or ethylene glycol ether, or with a mixture of diethylene glycol butyl ether and 20% sodium hydroxide, ammonia, ethanolamine, methanol, ethanol, glycerol, ethylene glycol butyl ether, 20% potassium hydroxide, or ethylene glycol ether, can achieve the objective of this invention.

[0058] Preparation method of plant extract bactericide: The extracts of *Malus hupehensis*, *Hypericum perforatum*, and *Melia azedarach* were dried, pulverized, and sieved using a 0.8 mm sieve. 30% of the base solution (water) was added to the reaction vessel according to the set weight percentage. The temperature was kept constant at 40℃. Then, the plant powder was added and thoroughly soaked and stirred. The temperature was then lowered to 28℃. While stirring, the extraction liquid (ethanol:ethylene glycol butyl ether: diethylene glycol butyl ether = 5:0.5:1 by mass percentage) was sprayed in. Then, the remaining 70% of the base solution (water) was added. After filtration, pressure filtration, three sedimentation processes, and centrifugation to remove impurities, the supernatant was taken and the pH was adjusted to 8.5 using 20% ​​potassium hydroxide. Extracts of *Malus hupehensis*, *Hypericum perforatum*, and *Melia azedarach* were obtained respectively.

[0059] The preparation method of emulsified cutting fluid includes the following steps: mixing base oil 1 and base oil 2 and heating to 125°C, adding oil-soluble rust inhibitor and stirring to dehydrate, then cooling to 80°C and adding emulsifier and stirring until fully dissolved, then cooling to 55°C and adding antioxidant and stirring evenly, finally adding emulsifying stabilizer and stirring evenly, then cooling to 30°C and adding plant extract bactericide.

[0060] Example 6

[0061] This embodiment of the emulsified cutting fluid using plant extracts as bactericides comprises the following components by weight: 20 parts base 1, 26 parts base oil 2, 12 parts oil-soluble rust inhibitor, 15 parts emulsifier, 0.2 parts antioxidant, 3 parts emulsion stabilizer, and 4 parts plant extract bactericide. Base 1 is 150SN or transformer oil, base oil 2 is a naphthenic mineral, and the plant extract bactericide is a mixture of extracts from *Malus spectabilis*, *Hypericum esculentum*, and *Melia azedarach*. The mass ratio of *Malus spectabilis* extract: *Hypericum esculentum* extract: *Melia azedarach* extract = 1:2.5:2.5.

[0062] In this embodiment, the oil-soluble rust inhibitor is medium-alkalinity calcium sulfonate. Replacing the medium-alkalinity calcium sulfonate in this embodiment with one of fatty acid oleic acid ester, synthetic petroleum sulfonate sodium, RC4295, T746, or T706, or with a mixture of medium-alkalinity calcium sulfonate and fatty acid oleic acid ester, synthetic petroleum sulfonate sodium, RC4295, T746, or T706, can achieve the purpose of this invention.

[0063] In this embodiment, the emulsifier is sorbitol oleate. Replacing the sorbitol oleate in this embodiment with one of sodium alkylbenzene sulfonate, sodium fatty acid soap, potassium fatty acid soap, fatty acid amine salt, fatty acid amide, petroleum sulfonic acid T702, or a mixture of sorbitol oleate and ...

[0064] In this embodiment, the emulsifying stabilizer is ethylene glycol ether. Replacing the ethylene glycol ether in this embodiment with one of the following: 20% sodium hydroxide, ammonia, ethanolamine, methanol, ethanol, glycerol, ethylene glycol butyl ether, diethylene glycol butyl ether, or 20% potassium hydroxide, or with a mixture of ethylene glycol ether and 20% sodium hydroxide, ammonia, ethanolamine, methanol, ethanol, glycerol, ethylene glycol butyl ether, diethylene glycol butyl ether, or 20% potassium hydroxide, can achieve the objective of this invention.

[0065] Preparation method of plant extract bactericide: The extracts of *Malus hupehensis*, *Hypericum perforatum*, and *Melia azedarach* were dried, pulverized, and sieved using a 0.8 mm sieve. 30% of the base solution (water) was added to the reaction vessel according to the set weight percentage. The temperature was kept constant at 40°C. Then, the plant powder was added and thoroughly soaked and stirred. The temperature was then lowered to 29°C. While stirring, the extraction liquid (ethanol:ethylene glycol butyl ether: diethylene glycol butyl ether = 5:0.5:1 by mass percentage) was sprayed in. Then, the remaining 70% of the base solution (water) was added. After filtration, pressure filtration, three sedimentation processes, and centrifugation to remove impurities, the supernatant was taken and the pH was adjusted to 8 using 20% ​​potassium hydroxide. Extracts of *Malus hupehensis*, *Hypericum perforatum*, and *Melia azedarach* were obtained respectively.

[0066] The preparation method of emulsified cutting fluid includes the following steps: mixing base oil 1 and base oil 2 and heating to 130°C, adding oil-soluble rust inhibitor and stirring to dehydrate, then cooling to 80°C and adding emulsifier and stirring until fully dissolved, then cooling to 55°C and adding antioxidant and stirring evenly, finally adding emulsifying stabilizer and stirring evenly, then cooling to 30°C and adding plant extract bactericide.

[0067] The cutting fluid of Example 1 was subjected to performance testing, and the test results are as follows:

[0068] In the above embodiments, the effects of embodiments 2-6 are all better than those of embodiment 1.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An emulsified cutting fluid using plant extracts as a bactericide, characterized in that: The emulsion raw material comprises the following components by weight: 15-28 parts base 1, 25-28 parts base oil 2, 8-16 parts oil-soluble rust inhibitor, 10-19 parts emulsifier, 0.0-0.6 parts antioxidant, 2-4 parts emulsion stabilizer, and 3-5 parts plant extract bactericide; wherein base 1 is 150SN or transformer oil, base oil 2 is naphthenic mineral oil, and the plant extract bactericide is a mixture of extracts from Malus hupehensis, hornwort, and neem trees.

2. The plant-based bactericide for metalworking fluids according to claim 1, characterized in that: The emulsion raw materials include the following components by weight: 20 parts base 1, 26 parts base oil 2, 12 parts oil-soluble rust inhibitor, 15 parts emulsifier, 0.2 parts antioxidant, 3 parts emulsion stabilizer, and 4 parts plant extract bactericide.

3. The emulsified cutting fluid using plant extracts as bactericides according to claim 1, characterized in that: By mass ratio, the extracts of Malus hupehensis, hornwort, and neem trees are 1:2-4:2-4.

4. The plant-based bactericide for metalworking fluids according to claim 3, characterized in that: The extract from *Malus hupehensis* is an extract from the old leaves of *Malus hupehensis*, and the extract from *Melia azedarach* is an extract from the bark of *Melia azedarach*.

5. The plant-based bactericide for metalworking fluids according to claim 1, characterized in that: The preparation of the plant extracts includes the following steps: drying and pulverizing the extracts of Malus hupehensis, hornwort, and chinaberry, then adding them to the extraction solution for extraction at room temperature, filtering, taking the supernatant, adjusting its pH to alkaline, and obtaining Malus hupehensis extract, hornwort extract, and chinaberry extract respectively.

6. The plant-based bactericide for metalworking fluids according to claim 5, characterized in that: The extract is one or a mixture of two or more of the following: ethanol, glycerol, ethanolamine, diethylene glycol butyl ether, ethylene glycol butyl ether, diethanol n-butyl ether, and triethanol monobutyl ether.

7. The emulsified cutting fluid using plant extracts as bactericides according to claim 1, characterized in that: The oil-soluble rust inhibitor is one or a mixture of two or more of the following: medium-alkalinity calcium sulfonate, fatty acid oleic acid ester, synthetic petroleum sulfonate sodium, RC4295, T746, and T706.

8. The emulsified cutting fluid using plant extracts as bactericides according to claim 1, characterized in that: The emulsifier is one or a mixture of two or more of the following: petroleum sulfonic acid T702, sodium heavy alkylbenzene sulfonate, sodium fatty acid soap, potassium fatty acid soap, fatty acid amine salt, fatty acid amide, sorbitol oleate, and Pingpingjia O-10.

9. The emulsified cutting fluid using plant extracts as bactericides according to claim 1, characterized in that: The antioxidant is T501, and the emulsifying stabilizer is one or a mixture of two or more of the following: 20% potassium hydroxide, 20% sodium hydroxide, ammonia, ethanolamine, methanol, ethanol, glycerol, ethylene glycol butyl ether, diethylene glycol butyl ether, and ethylene glycol ether.

10. The method for preparing the emulsified cutting fluid using plant extracts as bactericides according to claim 1, characterized in that: The process includes the following steps: Mix base oil 1 and base oil 2 and heat to 120-140℃, then add oil-soluble rust inhibitor and stir to dehydrate. Then cool to 70-90℃ and add emulsifier and stir until fully dissolved. Then cool to 50-60℃ and add antioxidant and stir evenly. Finally, add emulsion stabilizer and stir evenly. Then cool to 20-40℃ and add plant extract bactericide.

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