A green and environment-friendly water-based emulsion lubricant as well as a preparation method and application thereof

Abstract

The application provides a kind of green and environmental protection water-based emulsion lubricant and its preparation method and application, belong to plant oil-based water-based lubricating functional material technical field.The green and environmental protection water-based emulsion lubricant of the application is prepared from the following mass percentages of raw materials: maleic anhydride modified castor oil 1.25%~10%; cellulose biological emulsifier 2.5%~10%; co-emulsifier 1%~5%; defoaming agent 0.5~3%; the rest is water.In the application, the hydrophilic carboxyl of maleic anhydride modified castor oil is sufficient, the oil-water compatibility is excellent, and no harmful substances are generated, the biodegradation rate of modified oil is greater than or equal to 90%, the waste lubricating waste liquid is pollution-free, and it is much better than mineral oil-based lubricant; the emulsification system is environmentally friendly: food-grade cellulose derivatives are selected as emulsifiers, petroleum-based synthetic emulsifiers are replaced, co-emulsifiers and defoaming agents are matched, all components are low-toxicity and non-corrosive, and are suitable for textile, food machinery and precision metal processing environmental conditions.

Description

Technical Field

[0001] This invention relates to the field of plant oil-based and water-based lubricating functional materials, and in particular to a green and environmentally friendly water-based emulsion lubricant, its preparation method, and its application. Background Technology

[0002] Currently, most commercially available water-based lubricants are based on mineral oil and synthetic polyether petroleum-based oils, combined with anionic petroleum sulfonate emulsifiers, heavy metal additives, and halogen-containing defoamers. These lubricants have drawbacks such as poor biodegradability, wastewater discharge that pollutes water and soil, high toxicity of emulsifying additives, easy demulsification and stratification in hard water conditions, and poor adaptability to high and low temperatures. They are difficult to meet the requirements of green and low-carbon industrial practices, wastewater discharge that meets standards, and environmental and safety production control.

[0003] Castor oil is a natural, renewable vegetable oil with active hydroxyl groups and long-chain hydrophobic alkyl groups on its molecular side chains. It possesses inherent lubricating, friction-reducing, film-forming, and wear-resistant properties, and is completely biodegradable, making it an ideal green lubricant to replace mineral oil. However, virgin castor oil lacks hydrophilic groups, resulting in high oil-water interfacial tension. Direct emulsification with water easily leads to emulsion aggregation, sedimentation, and demulsification, making it impossible to directly prepare long-term stable water-based lubricating emulsions. Existing technologies mostly use single acrylic acid or epoxy-modified castor oil, resulting in insufficient hydrophilic carboxyl group content in the modified products and poor compatibility with emulsifiers. Furthermore, the industry commonly uses anionic and nonionic petroleum-based synthetic emulsifiers, which have low biodegradability and do not meet environmental standards. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a green and environmentally friendly water-based emulsion lubricant, its preparation method, and its application. The green and environmentally friendly water-based emulsion lubricant provided by this invention exhibits good compatibility among its components and is a water-based emulsion lubricant with high storage stability and high environmental friendliness.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a green and environmentally friendly water-based emulsion lubricant, which is made from raw materials comprising the following mass percentages: Maleic anhydride modified castor oil (MA-castor oil, modified castor oil) 1.25%~10%; cellulose-based bio-emulsifier 2.5%~10%; co-emulsifier 1%~5%; defoamer 0.5~3%; the remainder is water.

[0006] Preferably, the cellulose-based bioemulsifier includes one or more of hydroxypropyl methylcellulose, carboxymethyl cellulose, and hydroxyethyl cellulose.

[0007] Preferably, the co-emulsifier includes an alcohol-based co-emulsifier.

[0008] Preferably, the alcohol-based co-emulsifier includes one or more of ethylene glycol, propylene glycol, and ethanol.

[0009] Preferably, the defoamer is a polyether-modified silicone defoamer and / or propylene glycol block polyether.

[0010] Preferably, the maleic anhydride-modified castor oil is prepared by a method comprising the following steps: Castor oil, maleic anhydride, and 4-dimethylaminopyridine (DMAP) were mixed and subjected to an esterification addition reaction to obtain the maleic anhydride-modified castor oil.

[0011] Preferably, the molar ratio of castor oil to maleic anhydride is 1:2.5.

[0012] Preferably, the esterification addition reaction is carried out at a temperature of 110°C for 3.5 hours.

[0013] This invention also provides a method for preparing the green and environmentally friendly water-based emulsion lubricant described in the above technical solution, comprising the following steps: Maleic anhydride-modified castor oil, cellulose-based bio-emulsifier, and co-emulsifier were emulsified and premixed to obtain an oil phase premix; The oil phase premix and water are emulsified and dispersed to obtain a primary emulsion; The primary emulsion is mixed with an antifoaming agent to obtain the green and environmentally friendly water-based emulsion lubricant.

[0014] This invention also provides the application of the green and environmentally friendly water-based emulsion lubricant described in the above technical solution or the green and environmentally friendly water-based emulsion lubricant prepared by the preparation method described in the above technical solution in the field of lubrication.

[0015] This invention provides a green and environmentally friendly water-based emulsion lubricant, which is made from the following raw materials in the indicated mass percentages: 1.25%~10% maleic anhydride modified castor oil; 2.5%~10% cellulose-based bio-emulsifier; 1%~5% co-emulsifier; 0.5%~3% defoamer; and the remainder is water.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: The base material is green and biodegradable: Maleic anhydride-modified castor oil is used as raw material. Maleic anhydride is esterified and modified. Maleic anhydride-modified castor oil has sufficient hydrophilic carboxyl groups, excellent oil-water compatibility, and no harmful substances are generated. The biodegradability rate of the modified oil is ≥90%, and the waste lubricating liquid is pollution-free, which is far superior to mineral oil-based lubricants. The emulsification system is environmentally friendly and compatible: Food-grade cellulose derivatives are selected as emulsifiers to replace petroleum-based synthetic emulsifiers. It is formulated with emulsifiers and defoamers. All components are low in toxicity and non-corrosive, making it suitable for environmentally friendly working conditions in textile, food machinery, and precision metal processing.

[0017] Furthermore, the present invention specifies the preparation method of the maleic anhydride modified castor oil, specifically defining the temperature and raw material molar ratio of the esterification addition reaction. The esterification conversion rate is high, which further improves the hydrophilicity of the maleic anhydride modified castor oil and further enhances its oil-water compatibility.

[0018] Data from the embodiments show that the green and environmentally friendly water-based emulsion lubricant of the present invention has passed all six stability tests, is resistant to hard water, high and low temperatures, centrifugation, and freeze-thaw cycles, has minimal particle size fluctuation over 60 days, exhibits no stratification or demulsification, and its stability during storage, transportation, and field use far exceeds that of conventional vegetable oil water-based emulsions.

[0019] This invention also provides a method for preparing the green and environmentally friendly water-based emulsion lubricant described in the above technical solution. This invention involves room temperature emulsification throughout the process, requires no organic solvents, and does not require high-temperature and high-pressure reactions. It has low energy consumption, strong equipment adaptability, and can be mass-produced on a large scale, making it suitable for industrial batch production. Attached Figure Description

[0020] Figure 1 Comparison of FT-IR spectra of raw castor oil and castor oil modified with maleic anhydride; Figure 2 These are actual photos of the green and environmentally friendly water-based emulsion lubricant from Example 1 after 0 days, 30 days, and 60 days of storage. Figure 3 These are photos of the green and environmentally friendly water-based emulsion lubricant from Example 2 after 0 days, 30 days, and 60 days of storage. Figure 4 These are actual photos of the lubricant in Comparative Example 1 after 0 days and 30 days of storage. Figure 5 These are actual photos of the lubricant from Comparative Example 2 after 0 days, 30 days, and 60 days of storage. Figure 6 This is a particle size distribution diagram of the fresh 0d product of the green and environmentally friendly water-based emulsion lubricant in Example 4; Figure 7 This is a particle size distribution diagram of the green and environmentally friendly water-based emulsion lubricant in Example 4 after standing at room temperature for 7 days. Figure 8 This is a particle size distribution diagram of the green and environmentally friendly water-based emulsion lubricant in Example 4 after standing at room temperature for 30 days. Figure 9 This is a particle size distribution diagram of the green and environmentally friendly water-based emulsion lubricant of Example 4 after standing at room temperature for 60 days. Detailed Implementation

[0021] This invention provides a green and environmentally friendly water-based emulsion lubricant, which is made from raw materials comprising the following mass percentages: Maleic anhydride modified castor oil 1.25%~10%; cellulose-based bio-emulsifier 2.5%~10%; co-emulsifier 1%~5%; defoamer 0.5%~3%; the remainder is water.

[0022] In this invention, the mass percentage of maleic anhydride-modified castor oil in the raw materials can be 1.25%, 3%, 6%, 9%, or 10%.

[0023] In this invention, the maleic anhydride-modified castor oil is preferably prepared by a method comprising the following steps: Castor oil, maleic anhydride, and 4-dimethylaminopyridine were mixed and subjected to an esterification addition reaction to obtain the maleic anhydride-modified castor oil.

[0024] In this invention, the molar ratio of castor oil to maleic anhydride is preferably 1:2.5.

[0025] In this invention, the mass of the 4-dimethylaminopyridine is preferably 0.35% of the total mass of castor oil and maleic anhydride.

[0026] In this invention, the preferred temperature for the esterification addition reaction is 110°C, and the preferred time is 3.5 h.

[0027] In this invention, the heating rate from room temperature to the temperature of the esterification addition reaction is preferably 2~3℃ / min.

[0028] In this invention, the esterification addition reaction is preferably carried out in a protective atmosphere, which preferably includes nitrogen.

[0029] In this invention, the castor oil preferably undergoes pretreatment before use. The pretreatment preferably includes the following steps: adding refined dehydrated castor oil into a flask, stirring at a constant temperature of 75°C for 30 minutes, and removing trace amounts of bound water under vacuum to avoid water hydrolysis of maleic anhydride and reduction of esterification rate.

[0030] In this invention, the maleic anhydride is preferably ground through an 80-mesh sieve before use and sealed to prevent moisture before use.

[0031] The present invention preferably uses castor oil and maleic anhydride in a molar ratio of 1:2.5, and adds 0.35% of 4-dimethylaminopyridine by mass of the total mass of castor oil and maleic anhydride. High-purity nitrogen is introduced and the mixture is sealed for 25 minutes to prevent oxidation and carbonization of the vegetable oil. The stirring speed is 280 r / min, the temperature is raised to 110°C, and the esterification addition reaction is carried out at a constant temperature for 3.5 hours. During the esterification addition reaction, the castor oil side chain hydroxyl group undergoes ring-opening esterification with maleic anhydride, and a hydrophilic carboxyl functional group is added.

[0032] After the esterification addition reaction is completed, it is preferable to let it cool naturally to 60°C and remove unreacted free maleic anhydride small molecule monomers under vacuum for 40 minutes. Then, filter to remove trace amounts of 4-dimethylaminopyridine residue to obtain a brownish-yellow transparent viscous liquid, which is the maleic anhydride modified castor oil. It is preferable to store it in a sealed, light-proof container for later use.

[0033] In this invention, the mass percentage of cellulose-based bio-emulsifier in the raw materials can be 2.5%, 3%, 9%, or 10%.

[0034] In this invention, the cellulose-based bio-emulsifier preferably includes one or more of hydroxypropyl methylcellulose, carboxymethyl cellulose, and hydroxyethyl cellulose. When the cellulose-based bio-emulsifier preferably includes a mixture of two substances, this invention does not impose any special limitations on the types and mass ratios of the substances in the mixture.

[0035] In this invention, the mass percentage of the co-emulsifier in the raw materials can be 1%, 3%, 4.5% or 5%.

[0036] In this invention, the co-emulsifier preferably includes an alcohol-based co-emulsifier.

[0037] In this invention, the alcohol-based co-emulsifier preferably includes one or more of ethylene glycol, propylene glycol, and ethanol.

[0038] In this invention, the mass percentage of defoamer in the raw materials can be 0.5%, 1%, 2% or 3%.

[0039] In this invention, the defoamer is preferably a polyether-modified silicone defoamer and / or a propylene glycol block polyether.

[0040] This invention uses maleic anhydride to directionally esterify the hydroxyl groups of castor oil, linking hydrophilic cyclic carboxyl groups into the castor oil molecules, significantly improving the oil's water dispersibility. It uses edible-grade cellulose-based bio-emulsifiers as emulsifiers, combined with non-toxic polyols to aid emulsification, and compounded with low-foaming, biocompatible polyether defoamers and / or propylene glycol block polyethers. The entire process involves no organic solvents or toxic additives, and all components are biodegradable, free of aromatic mineral oils, phosphorus- and chlorine-containing extreme pressure additives, making it green, low-toxic, and easily degradable. This green and environmentally friendly water-based emulsion lubricant exhibits high storage stability and environmental friendliness, overcoming the technical shortcomings of existing vegetable oil-based water-based lubricants, such as poor stability, environmentally unfriendly emulsion systems, and incomplete performance characterization.

[0041] This invention also provides a method for preparing the green and environmentally friendly water-based emulsion lubricant described in the above technical solution, comprising the following steps: Maleic anhydride-modified castor oil, cellulose-based bio-emulsifier, and co-emulsifier were emulsified and premixed to obtain an oil phase premix; The oil phase premix and water are emulsified and dispersed to obtain a primary emulsion; The primary emulsion is mixed with an antifoaming agent to obtain the green and environmentally friendly water-based emulsion lubricant.

[0042] This invention involves emulsifying and premixing maleic anhydride-modified castor oil, cellulose-based bio-emulsifiers, and co-emulsifiers to obtain an oil-phase premix.

[0043] In this invention, the temperature of the emulsified premix is ​​preferably room temperature, i.e., no additional heating or cooling is required.

[0044] In this invention, the emulsification premixing time is preferably 20 min, the emulsification premixing is preferably carried out under stirring, and the stirring speed is preferably 3000 r / min.

[0045] In this invention, the maleic anhydride-modified castor oil is added to a beaker at 25°C, followed by the sequential addition of a cellulose-based bio-emulsifier and a co-emulsifier. The mixture is stirred at a constant speed of 3000 r / min for 20 min to achieve complete miscibility between the oil and the emulsifying agent, thereby obtaining the oil phase premix.

[0046] After obtaining the oil phase premix, the present invention emulsifies and disperses the oil phase premix with water to obtain a primary emulsion.

[0047] In this invention, the water is preferably added dropwise to the oil phase premix at a uniform rate, and the preferred dropping time is 40 minutes.

[0048] In this invention, the emulsification and dispersion temperature is preferably room temperature, the time is preferably 60 min, the emulsification and dispersion is preferably carried out under stirring, and the stirring speed is preferably 550 r / min.

[0049] After obtaining the primary emulsion, the present invention mixes the primary emulsion with an antifoaming agent to obtain the green and environmentally friendly water-based emulsion lubricant.

[0050] The present invention preferably adds the defoamer to the primary emulsion.

[0051] In this invention, the mixing is preferably carried out at room temperature and 3000 r / min for 15 min to eliminate emulsion encapsulation of air bubbles and avoid emulsion foaming and demulsification.

[0052] After the mixing is completed, the process preferably includes filtering the resulting mixture. The purpose of the filtration is to remove trace amounts of flocculent particles to obtain a milky white, highly fluid, green water-based emulsion lubricant product, namely the green and environmentally friendly water-based emulsion lubricant.

[0053] This invention also provides the application of the green and environmentally friendly water-based emulsion lubricant described in the above technical solution or the green and environmentally friendly water-based emulsion lubricant prepared by the preparation method described in the above technical solution in the field of lubrication.

[0054] In this invention, the green and environmentally friendly water-based emulsion lubricant is preferably suitable for all scenarios including metal processing, textile drawing, water-cooled lubrication of civil machinery, and surface lubrication of medical devices, and can replace traditional mineral oil-based non-environmentally friendly water-based lubricants.

[0055] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0056] In the embodiments and comparative examples of this invention, unless otherwise specified, the amounts of raw materials used are all parts by mass.

[0057] In the embodiments and comparative examples of this invention, the propylene glycol block polyether defoamer used was P-06 defoamer produced by Shandong Puniao New Material Technology Co., Ltd., and the polyether modified silicone defoamer was MY-223C defoamer produced by Shandong Puniao New Material Technology Co., Ltd.

[0058] Example 1 (1) Take 100 mol of dehydrated refined castor oil and 250 mol of maleic anhydride, add 0.35% of DMAP by mass, purge oxygen with nitrogen for 25 min, stir at 280 r / min, heat to 110℃ at 2℃ / min for esterification reaction for 3.5 h, remove free monomers under vacuum at 60℃ for 40 min, filter to obtain brownish-yellow maleic anhydride modified castor oil, and confirm the completion of esterification grafting by FT-IR detection.

[0059] (2) 1.25 parts of maleic anhydride modified castor oil, 2.0 parts of hydroxypropyl methylcellulose, 0.5 parts of carboxymethyl cellulose, 4.5 parts of propylene glycol, 0.5 parts of propylene glycol block polyether defoamer, and 91.25 parts of deionized water; premix the modified castor oil at room temperature with a dual cellulose emulsifier (including hydroxypropyl methylcellulose and carboxymethyl cellulose) and a propylene glycol co-emulsifier, and stir at 3000 r / min for 20 min; add deionized water dropwise at 550 r / min and emulsify for 60 min, then add the defoamer at 3000 r / min and defoam for 15 min, filter, and obtain the green and environmentally friendly water-based emulsion lubricant.

[0060] Comparative Example 1 (1) The preparation of maleic anhydride modified castor oil is the same as in Example 1.

[0061] (2) Same as Example 1, except that the raw material components are: 1.25 parts of maleic anhydride modified castor oil, 1 part of hydroxypropyl methylcellulose, 0.25 parts of carboxymethyl cellulose, 4.5 parts of propylene glycol, 0.5 parts of propylene glycol block polyether defoamer, and 92.5 parts of deionized water.

[0062] Example 2 (1) The preparation of maleic anhydride modified castor oil is the same as in Example 1.

[0063] (2) Same as Example 1, except that the raw material components are: 10 parts of maleic anhydride modified castor oil, 5 parts of hydroxypropyl methylcellulose, 5 parts of hydroxyethyl cellulose, 1 part of ethylene glycol, 1 part of propylene glycol block polyether defoamer, and 78 parts of deionized water.

[0064] Comparative Example 2 (1) The preparation of maleic anhydride modified castor oil is the same as in Example 1.

[0065] (2) Same as Example 1, except that the raw material components are: 10 parts of maleic anhydride modified castor oil, 10 parts of hydroxypropyl methylcellulose, 10 parts of carboxymethyl cellulose, 1 part of ethylene glycol, 1 part of propylene glycol block polyether defoamer, and 68 parts of deionized water.

[0066] Example 3 (1) The preparation of maleic anhydride modified castor oil is the same as in Example 1.

[0067] (2) Same as Example 1, except that the raw material components are: 6 parts of maleic anhydride modified castor oil, 1 part of carboxymethyl cellulose, 2 parts of hydroxyethyl cellulose, 3 parts of ethanol, 2 parts of polyether modified silicone defoamer, and 86 parts of deionized water.

[0068] Example 4 (1) The preparation of maleic anhydride modified castor oil is the same as in Example 1.

[0069] (2) Same as Example 1, except that the raw material components are: 3 parts maleic anhydride modified castor oil, 5 parts hydroxypropyl methylcellulose, 4 parts sodium carboxymethyl cellulose, 4.5 parts propylene glycol, 3 parts polyether modified silicone defoamer, and 80.5 parts deionized water.

[0070] Example 5 (1) The preparation of maleic anhydride modified castor oil is the same as in Example 1.

[0071] (2) Same as Example 1, except that the raw material components are: 9 parts of maleic anhydride modified castor oil, 1.5 parts of hydroxypropyl methylcellulose, 1.5 parts of hydroxyethyl cellulose, 5 parts of propylene glycol, 2 parts of polyether modified silicone defoamer, and 81 parts of deionized water.

[0072] Structural characterization and stability testing Figure 1 The image shows a comparison of the FT-IR spectra of raw castor oil and castor oil modified with maleic anhydride. The characteristic infrared peak of raw castor oil is assigned to 3392 cm⁻¹. -1 Broad peaks at 2926 and 2854 cm⁻¹ for the stretching vibration of the free hydroxyl (-OH) group in the side chain of castor oil molecules. -1 Characteristic peaks for stretching of long-chain alkyl groups in oleic acids and fats (-CH2, -CH3); 1741 cm⁻¹ -1 : Triglyceride ester group C=O stretching vibration peak; 1456 cm⁻¹ -1 Alkyl bending vibration peak; 1168 cm⁻¹ -1 : CoC skeleton stretching peak in oils; characteristic absorption peaks without carboxyl groups or acid anhydrides; infrared characteristic peak assignment for maleic anhydride-modified castor oil: 3392 cm⁻¹ -1 The intensity of the hydroxyl absorption peak decreased significantly, and the peak area decreased by 68%, proving that the hydroxyl groups in castor oil were consumed in the ring-opening esterification reaction; new peaks were observed at 1785 and 1726 cm⁻¹. -1 The two peaks represent the characteristic stretching peaks of the cyclic carboxyl group and the C=O bond of the modified monoester, respectively, and are characteristic peaks of maleic anhydride esterification grafting; 1642 cm⁻¹ -1 The characteristic peaks of carbon-carbon double bonds retained after maleic anhydride incorporation; the absence of fracture and decomposition of the original oil skeleton peaks proves that only hydroxyl esterification occurred during modification, and the long-chain lubricating skeleton of the oil was completely preserved; in summary, the infrared results prove that maleic anhydride successfully underwent ring-opening addition esterification with the hydroxyl groups of castor oil, and the target modified product was successfully synthesized.

[0073] Figure 2 These are photos of the green and environmentally friendly water-based emulsion lubricant from Example 1 after 0 days, 30 days, and 60 days of storage. Figure 3 These are photos of the green and environmentally friendly water-based emulsion lubricant from Example 2 after 0 days, 30 days, and 60 days of storage. Figure 4 These are actual photos of the lubricant from Comparative Example 1 after 0 days and 30 days of storage. Figure 5 The images show the lubricant from Comparative Example 2 after 0, 30, and 60 days of storage. It can be seen that the emulsions from Examples 1 and 2 remained stable without stratification after 30 and 60 days. Comparative Example 1, due to the reduced amount of cellulose-based bio-emulsifier, could not remain stable and showed obvious stratification after 30 days. Comparative Example 2, due to the increased amount of cellulose-based bio-emulsifier, although not stratified, had excessively high viscosity, which is detrimental to its application in various fields. These results indicate that cellulose-based bio-emulsifiers play a crucial role in emulsion systems. Insufficient addition leads to a thin interfacial film, insufficient viscosity causing oil droplet aggregation, stratification, and demulsification. Excessive addition leads to free polymer bridging and flocculation, excessive viscosity, easy microbial growth, and poor processing performance. Only within the range between the critical saturation adsorption amount and the upper limit of safe viscosity can emulsification, stability, fluidity, and storage properties simultaneously achieve optimal performance.

[0074] Emulsion stability evaluation criteria and optimal formulation test results Test environment: room temperature 25℃, high temperature environment 55℃, freeze-thaw cycle -18℃↔25℃, six stability tests were performed in accordance with the national standard GB / T 6144-2010 for water-based lubricants.

[0075] 1. pH storage stability The pH values ​​of each embodiment and comparative example at 0d and 60d are shown in Table 1 below. Each embodiment showed no rancidity, no significant pH fluctuations, and the oils did not hydrolyze or deteriorate.

[0076] Table 1. pH storage stability test results of the examples

[0077] 2. Calcium ion stability (hard water resistance stability) A 0.5wt% CaCl2 hard water solution was prepared. The lubricant and hard water solution were mixed at a volume ratio of 1:5 and allowed to stand for 24 hours. Examples 1 to 5 and Comparative Example 2 showed no floating oil, no flocculation, and no stratification. They are suitable for industrial groundwater and hard circulating water lubrication conditions. Comparative Example 1 stratified after standing for 24 hours, and Comparative Example 2 had too high viscosity and could not be used for subsequent applications.

[0078] 3. Dilution stability The emulsion was diluted 10 times with tap water and allowed to stand for 48 hours. The emulsion concentrations of Examples 1 to 5 and Comparative Example 2 were uniform, with no oil floating or solid sedimentation. The emulsion performance was stable when diluted with water. Comparative Example 1 separated into layers after standing for 48 hours.

[0079] 4. High-temperature storage stability After being kept at a constant temperature of 55℃ and sealed for 72 hours, the emulsions of Examples 1 to 5 and Comparative Example 2 did not separate, thicken, or turn black. The cellulose emulsion system was heat-resistant and did not dissociate, exhibiting excellent thermal stability. Comparative Example 1 separated after being heated and left to stand for 72 hours.

[0080] 5. Centrifugal stability Centrifuge at 3500 r / min for 30 min. Examples 1 to 5 and Comparative Example 2 showed no sediment at the bottom and no floating oil on the surface of the emulsion, indicating strong emulsification and resistance to emulsion breakage during transportation. Comparative Example 1 showed obvious stratification after centrifugation.

[0081] 6. Freeze-thaw cycle stability Freezing at -18℃ for 12 hours and thawing at 25℃ for 12 hours constitutes one cycle. Examples 1 to 5 and Comparative Example 2 completed 5 freeze-thaw cycles. After the emulsion returned to room temperature, it was homogeneous and clear, without demulsification or agglomeration, and had strong adaptability to low-temperature storage and transportation. The emulsion in Comparative Example 1 showed stratification after returning to room temperature.

[0082] Results of periodic particle size distribution monitoring of emulsion (Dynamic Light Scattering DLS particle size analyzer) Figure 6 This is a particle size distribution diagram of the fresh 0d product of the green and environmentally friendly water-based emulsion lubricant in Example 4. Figure 7 This is a particle size distribution diagram of the green and environmentally friendly water-based emulsion lubricant from Example 4 after standing at room temperature for 7 days. Figure 8 This is a particle size distribution diagram of the green and environmentally friendly water-based emulsion lubricant from Example 4 after standing at room temperature for 30 days. Figure 9 The particle size distribution diagram of the green and environmentally friendly water-based emulsion lubricant in Example 4 after standing at room temperature for 60 days is shown. The test temperature was 25℃, and the hydrated particle size was tested by dilution 100 times. The average particle size and particle size distribution index (PDI) were monitored regularly to determine the long-term emulsification stability of the emulsion. It can be seen that: 0-day fresh product: average particle size 137nm, PDI=0.162, narrow particle size distribution, uniform emulsification; 7 days after standing at room temperature: average particle size 144nm, PDI=0.165, no obvious agglomeration or growth of particles; 30 days after standing at room temperature: average particle size 197nm, PDI=0.171, slight increase in particle size, stable system; 60 days after standing at room temperature: average particle size 224nm, PDI=0.178, no agglomeration or bursting, no particle size differentiation, the cellulose emulsion film can effectively encapsulate the modified oil, and the emulsion particle size is controllable and stable in the long term.

[0083] The particle size stability results of each embodiment are as follows: Comparative Example 2 > Example 4 > Example 1 > Example 2 > Example 3 > Example 5 > Comparative Example 1. This is attributed to the amount of cellulose-based bio-emulsifier added and the mass ratio of maleic anhydride-modified castor oil to cellulose-based bio-emulsifier. With a fixed total system mass, the lower the proportion of maleic anhydride-modified castor oil and the higher the proportion of cellulose-based bio-emulsifier, the smaller the total surface area of ​​oil droplets, the more complete the interfacial film coverage, the higher the viscosity of the continuous phase, and the fewer oil droplet collisions. This results in stronger anti-stratification and anti-agglomeration capabilities of the emulsion, and a more stable emulsion. Conversely, the more maleic anhydride-modified castor oil and the less cellulose-based bio-emulsifier, the less interfacial protection, the insufficient viscosity, and the rapid merging and stratification of oil droplets, leading to poorer emulsion stability. Meanwhile, cellulose-based bio-emulsifiers also follow the principle of moderate addition. If the addition is too small, the interfacial film thickness will be insufficient, and it will be unable to encapsulate oil droplets; the viscosity of the aqueous phase will be too low, and it will be unable to inhibit the floating of oil droplets; the salt resistance, temperature resistance, and storage stability will be extremely poor. If the addition is too large, the viscosity will be too high, resulting in loss of fluidity, making processing / use difficult, and excess free polymers will cause flocculation and reverse demulsification; the system defects will increase, and the stability will decrease in the opposite direction. Therefore, only in the middle range between the critical saturation adsorption amount and the upper limit of the safe viscosity can emulsification, stability, fluidity, and storage properties be optimized simultaneously.

[0084] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A green and environmentally friendly water-based emulsion lubricant, characterized in that, It is made from raw materials comprising the following mass percentages: Maleic anhydride modified castor oil 1.25%~10%; cellulose-based bio-emulsifier 2.5%~10%; co-emulsifier 1%~5%; defoamer 0.5%~3%; the remainder is water.

2. The green and environmentally friendly water-based emulsion lubricant according to claim 1, characterized in that, The cellulose-based bioemulsifiers include one or more of hydroxypropyl methylcellulose, carboxymethyl cellulose, and hydroxyethyl cellulose.

3. The green and environmentally friendly water-based emulsion lubricant according to claim 1, characterized in that, The co-emulsifiers include alcohol-based co-emulsifiers.

4. The green and environmentally friendly water-based emulsion lubricant according to claim 3, characterized in that, The alcohol-based co-emulsifiers include one or more of ethylene glycol, propylene glycol, and ethanol.

5. The green and environmentally friendly water-based emulsion lubricant according to claim 1, characterized in that, The defoamer is a polyether-modified silicone defoamer and / or propylene glycol block polyether.

6. The green and environmentally friendly water-based emulsion lubricant according to claim 1, characterized in that, The maleic anhydride-modified castor oil is prepared by a method comprising the following steps: Castor oil, maleic anhydride, and 4-dimethylaminopyridine were mixed and subjected to an esterification addition reaction to obtain the maleic anhydride-modified castor oil.

7. The green and environmentally friendly water-based emulsion lubricant according to claim 6, characterized in that, The molar ratio of castor oil to maleic anhydride is 1:2.

5.

8. The green and environmentally friendly water-based emulsion lubricant according to claim 6, characterized in that, The esterification addition reaction was carried out at a temperature of 110°C for 3.5 hours.

9. The method for preparing the green and environmentally friendly water-based emulsion lubricant according to any one of claims 1 to 8, characterized in that, Includes the following steps: Maleic anhydride-modified castor oil, cellulose-based bio-emulsifier, and co-emulsifier were emulsified and premixed to obtain an oil phase premix; The oil phase premix and water are emulsified and dispersed to obtain a primary emulsion; The primary emulsion is mixed with an antifoaming agent to obtain the green and environmentally friendly water-based emulsion lubricant.

10. The application of the green and environmentally friendly water-based emulsion lubricant according to any one of claims 1 to 8 or the green and environmentally friendly water-based emulsion lubricant prepared by the preparation method according to claim 9 in the field of lubrication.

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