A lubricating oil filter material and a method for making the same

Abstract

The application discloses a lubricating oil filtering material and a preparation method thereof, and belongs to the technical field of filtering materials. The lubricating oil filtering material comprises, from outside to inside, a coarse filtering layer, a dehydration layer and a fine filtering layer. The coarse filtering layer is made of polyester fiber filter cloth with a pore size of 5-100 mu m. The fine filtering layer is made of glass fiber filter paper with a precision of 0.5-20 mu m. The dehydration layer comprises a water-absorbing nanofiber membrane layer and a water-absorbing polyurethane layer attached to the surface of the nanofiber membrane layer. The composite nanofiber membrane layer is obtained by mixing and reacting acrylic acid-acrylamide copolymer, citric acid modified polyvinyl alcohol and crosslinking agent glutaraldehyde, and then spinning. The water-absorbing polyurethane layer is obtained by reacting shell-core structure ion exchange resin, isocyanate monomer, polyethylene glycol and tris(3-hydroxypropyl)amine, and then compounding with an antioxidant. The acrylic acid-acrylamide copolymer is obtained by copolymerizing acrylic acid, acrylamide and 2-bromoethyl acrylate.

Description

Technical Field

[0001] This invention relates to a lubricating oil filter material and its preparation method. Background Technology

[0002] Lubricating oil plays a vital role in industrial production and the operation of machinery. It reduces friction between equipment parts, lowers wear, dissipates heat, and prevents corrosion, thereby ensuring the normal operation of equipment and extending its service life. However, in actual use, lubricating oil inevitably becomes contaminated. The main contaminants include solid particles and moisture, which can seriously affect the performance of the lubricating oil and the normal operation of the equipment.

[0003] For solid particulate matter removal, there are relatively many types of filter materials available on the market, commonly including PP / PE filter bags, corrugated glass fiber filter cartridges, and plant fiber filter cartridges. These filter materials are effective in removing mechanical impurities and can effectively intercept solid particles in lubricating oil, maintaining its cleanliness to a certain extent. However, they have a significant limitation: they only have the single function of removing mechanical impurities and cannot treat moisture in lubricating oil.

[0004] Existing methods for purifying and dehydrating lubricating oil mainly include vacuum dehydration and coalescence separation dehydration. Vacuum dehydration is inefficient, time-consuming, and energy-intensive. While coalescence separation dehydration can achieve some degree of dehydration, its removal precision is limited, it is ineffective at removing tiny water droplets, and its contaminant holding capacity is extremely poor, leading to easy clogging of the filter material and frequent replacement. More importantly, both of these dehydration methods require heating the oil. Repeated heating promotes further oxidation of the oil, accelerates its deterioration, reduces its lifespan, and increases equipment operating costs and maintenance complexity.

[0005] In practical equipment applications, it is often necessary to remove both water from lubricating oil and mechanical impurities. To achieve these two functions, it is usually necessary to combine different functional units, that is, to combine the dehydration device and the device for removing mechanical impurities together. However, this combination of functional units increases the space occupied by the equipment, makes the equipment structure more complex, increases the difficulty of installation and maintenance, and also increases the manufacturing cost and floor space required for the equipment.

[0006] In conclusion, there is an urgent need in the market for a lubricating oil filter material that can effectively remove solid particles from lubricating oil and efficiently remove moisture. Summary of the Invention

[0007] The purpose of this invention is to provide a lubricating oil filter material and its preparation method to solve the technical problems mentioned in the background section.

[0008] The technical solution to achieve the objective of this invention is:

[0009] In a first aspect, the present invention discloses a lubricating oil filter material, which has three functions: efficient dehydration, removal of acidic oxides and efficient retention of fine solid particles, comprising, from the outside to the inside, a coarse filter layer, a dehydration layer and a fine filter layer; the dehydration layer comprises a water-absorbing nanofiber membrane layer and a water-absorbing polyurethane layer attached to the surface of the nanofiber membrane layer.

[0010] The lubricating oil filter material of the present invention comprises, from the outside to the inside, a coarse filter layer, a dehydration layer, and a fine filter layer. The dehydration layer includes a water-absorbing nanofiber membrane layer and a water-absorbing polyurethane layer attached to the surface of the nanofiber membrane layer, which increases the water absorption of the dehydration layer. The lubricating oil can be dehydrated at room temperature. During the filtration of lubricating oil, it first passes through the coarse filter layer to intercept large solid particles, then passes through the dehydration layer for dehydration, and finally passes through the fine filter layer to intercept and filter the remaining small solid particles in the dehydrated lubricating oil. Thus, by using only the lubricating oil filter material prepared by the present invention to filter lubricating oil, solid particles in the lubricating oil can be effectively removed and water in the lubricating oil can be efficiently removed.

[0011] Furthermore, the coarse filter layer is made of polyester fiber filter cloth with a pore size of 5 to 100 μm to intercept large solid particles.

[0012] Furthermore, the absorbent nanofiber membrane is obtained by mixing and spinning acrylic acid, acrylamide, ethyl bromide 2-acrylate, citric acid-modified polyvinyl alcohol, and the crosslinking agent glutaraldehyde. By modifying polyvinyl alcohol with citric acid, a branched structure with citric acid as the branching center and polyvinyl alcohol as the branch chain is formed. At the same time, acrylic acid, acrylamide, and ethyl bromide 2-acrylate are introduced to polymerize and form an interpenetrating network structure of absorbent nanofiber membrane. This not only increases the water absorption of the absorbent nanofiber membrane but also effectively enhances its water resistance.

[0013] Furthermore, the water-absorbing polyurethane layer is obtained by reacting a core-shell structured ion exchange resin, isocyanate monomer, polyethylene glycol, and tris(3-hydroxypropyl)amine with an antioxidant. The amino groups on the surface of the core-shell structured ion exchange resin, the hydroxyl groups on polyethylene glycol and tris(3-hydroxypropyl)amine react with the hydroxyl groups on the isocyanate monomer to form a branched structure of water-absorbing polyurethane with the core-shell structured ion exchange resin and tris(3-hydroxypropyl)amine as branching centers and polyethylene glycol urethane as branched chains. This branched structure is introduced into the cavity, ensuring good water absorption while further enhancing the water-absorbing polyurethane's properties. The process effectively filters solid particulate impurities in lubricating oil and improves the water resistance of the water-absorbing polyurethane layer. Furthermore, the introduction of a core-shell structured ion exchange resin creates a micro-nano protrusion hydrophilic structure on the surface of the water-absorbing polyurethane layer. When the dehydrated layer comes into contact with undehydrated lubricating oil, water is trapped within this micro-nano protrusion hydrophilic structure, forming a water film on the surface of the dehydrated layer. Utilizing the immiscibility of oil and water, the oil phase and water phase in the lubricating oil are separated, achieving dehydration and leaving no residue of the oil phase in the dehydrated layer. The introduction of antioxidants ensures that the lubricating oil is not easily oxidized during the filtration process.

[0014] The core-shell structured ion exchange resin is prepared by first using emulsion polymerization to prepare polystyrene microspheres, then sulfonating the polystyrene microspheres, followed by hydrolysis of tetraethyl silicate on the surface of the sulfonated polystyrene microspheres to form a silica layer. Subsequently, it is modified with 1,2-bis(trimethoxysilyl)ethane, triethoxy-3-(2-imidazol-1-linyl)propane, and 3-aminopropyltriethoxysilane. The surfactant cetyltrimethylammonium bromide is further removed by solvent extraction to form a mesoporous silica shell, resulting in a core-shell structured ion exchange resin. Modifying the sulfonated polystyrene microspheres coated with a silica layer by hydrolyzing triethoxy-3-(2-imidazol-1-linyl)propane, 3-aminopropyltriethoxysilane, and 1,2-bis(trimethoxysilyl)ethane effectively improves the hydrophilicity and dispersibility of the sulfonated polystyrene microspheres in the water-absorbing polyurethane layer.

[0015] Furthermore, the fine filter layer uses glass fiber filter paper with a precision of 0.5 to 20 μm; it further filters the dehydrated lubricating oil to intercept small solid particles remaining in the dehydrated lubricating oil.

[0016] Furthermore, the lubricating oil filter material can also be used for the filtration and purification of gasoline, diesel, and other organic liquid substances.

[0017] In a second aspect, a method for preparing a lubricating oil filter material as described in the first aspect is characterized by comprising the following preparation steps:

[0018] S1. Immerse the water-absorbing nanofiber membrane in water-absorbing polyurethane for 4-6 minutes, then lift it vertically and bake it in an oven at 60°C for 23-25 ​​hours. Place it in a sealed environment for 2 days to obtain a dehydrated layer. In this step, a water-absorbing polyurethane layer is formed on the surface of the water-absorbing nanofiber membrane. At the same time, the imidazole and tertiary amine in the polyurethane layer react with the bromoethane in the water-absorbing nanofiber membrane, consuming the hydrophobic bromoethane and forming hydrophilic imidazole salt and quaternary ammonium salt, which endow the dehydrated layer with good antibacterial properties and further enhance the water absorption of the dehydrated layer. Meanwhile, the water-absorbing polyurethane layer is firmly attached to the surface of the water-absorbing nanofiber membrane, which enhances the water resistance of the dehydrated layer.

[0019] S3. Stack the coarse filter layer, the dehydration layer obtained in step S1, and the fine filter layer in sequence from the outside to the inside, and then fold them into a continuous W shape to obtain the lubricating oil filter material.

[0020] Furthermore, the preparation steps of the water-absorbing nanofiber membrane are as follows:

[0021] A1. Mix 2 parts by mass of polyvinyl alcohol with 20 parts by mass of deionized water, heat to 88-92°C under stirring, and after the polyvinyl alcohol is completely dissolved in the deionized water, cool to the reaction temperature of 58-62°C. Then, add 18-20 parts by mass of 0.8-0.9 g / mL citric acid aqueous solution at a rate of 1 drop / s. After the addition is completed, keep warm for 3 hours, then stop stirring, add anhydrous ethanol as a precipitant to precipitate the product from the solution, filter, and then extract with anhydrous ethanol in a Soxhlet extractor for 11.5-12.5 hours. Dry under vacuum at 28-32°C to obtain citric acid modified polyvinyl alcohol. Mix 1 part by mass of citric acid modified polyvinyl alcohol with 9 parts by mass of deionized water, stir and heat to 90-95°C, and continue stirring until the citric acid modified polyvinyl alcohol is dissolved to obtain a 10% citric acid modified polyvinyl alcohol aqueous solution.

[0022] A2. Neutralize 3 parts by mass of acrylic acid with 20% sodium hydroxide solution in an ice-water bath, then add 1-1.5 parts by mass of acrylamide at room temperature and mix thoroughly. Next, add 0.07-0.09 parts by mass of emulsifier and stir to disperse evenly. Then add 0.1-0.3 parts by mass of ethyl bromide 2-acrylate and continue stirring to disperse evenly. Then add 7-8 parts by mass of 10% citric acid modified polyvinyl alcohol aqueous solution, 0.02-0.04 parts by mass of potassium persulfate initiator and 23-24 parts by mass of deionized water. Stir at 90 rpm for 25-35 min under nitrogen atmosphere and at 38-42℃. Then raise the temperature to 68-72℃ and continue stirring for 55-65 min. Then raise the temperature to 78-82℃ and stir at 130-140 rpm for 25-35 min. After the reaction is completed, keep stirring and cool down to 58-62℃. Add 0.18-0.20 parts by mass of 25% glutaraldehyde aqueous solution to obtain spinning solution.

[0023] A3. After ultrasonically treating the spinning solution for 25-30 minutes with an ultrasonic cleaner to remove bubbles, place it in an electrostatic spinning machine and spin it using tin foil as a collecting screen. After spinning, treat it at 155-160℃ for 28-32 minutes, and immediately place it in a vacuum preservation container to obtain a water-absorbing nanofiber membrane.

[0024] Furthermore, the preparation steps of the water-absorbing polyurethane layer are as follows:

[0025] Five parts by weight of polyethylene glycol, 1.2-1.3 parts by weight of tris(3-hydroxypropyl)amine, and 50-55 parts by weight of N,N-dimethylacetamide were mixed and then heated to 58-62°C and stirred for 55-65 min. Then, 0.3-0.8 parts by weight of shell-core structured ion exchange resin were added and ultrasonically dispersed for 55-65 min. Next, 14-18 parts by weight of isophorone diisocyanate and 0.0002-0.0004 parts by weight of dibutyltin dilaurate catalyst were added, and the mixture was heated to 78-82°C and stirred for 4.5-5.5 h. Then, the mixture was cooled to 38-42°C, and 10-20% of N,N-dimethylacetamide aqueous solution was added. The reaction was continued for 23-25 ​​h. After cooling to room temperature, 0.02-0.04 parts by weight of antioxidant were added to obtain a water-absorbing polyurethane layer with a solid content of 20-40%.

[0026] Furthermore, the preparation steps of the core-shell structured ion exchange resin are as follows:

[0027] (1) Dissolve 0.55-0.65 parts by weight of polyvinylpyrrolidone in 50 parts by weight of deionized water, then add 5.90-5.92 parts by weight of styrene, heat to 74-76°C, and maintain under nitrogen atmosphere for 8-12 minutes. Finally, add an initiator solution obtained by dissolving 0.14-0.16 parts by weight of potassium persulfate in 20 parts by weight of water, react for 23-25 ​​hours, centrifuge and wash 2-4 times with deionized water and anhydrous ethanol, and dry in a freeze dryer to obtain polystyrene microspheres;

[0028] (2) Under nitrogen protection, stirring and reflux, 0.15-0.25 parts by mass of polystyrene microspheres were slowly added to a mixed solution obtained by mixing 265-266 parts by mass of dichloromethane and 17-18 parts by mass of chlorosulfonic acid. Then, the sulfonation reaction was carried out at 55-65°C for 5-7 hours. After washing with deionized water until the pH was neutral, the microspheres were centrifuged and washed 2-4 times with anhydrous ethanol. Then, the microspheres were dried overnight in a freeze dryer to obtain sulfonated polystyrene microspheres.

[0029] (3) Take 0.2 parts by weight of sulfonated polystyrene microspheres, 60 parts by weight of deionized water, 15-16 parts by weight of anhydrous ethanol, 0.15-0.25 parts by weight of hexadecyl dimethyl ammonium bromide, and 0.65-0.69 parts by weight of 10% ammonia water, sonicate for 13-17 minutes, then heat to 48-52°C and stir continuously for 25-35 minutes. Then add 0.4-0.6 parts by weight of tetraethyl silicate and stir for 1.5-2.5 hours. After that, add 2.3-2.4 parts by weight of an ethanol solution containing 0.07-0.09 parts by weight of hexadecyl dimethyl ammonium bromide and 0.18-0.20 parts by weight of 10% ammonia water, stir for 0.4-0.6 hours, and then add 0.2-0.3 parts by weight of ethanol solution. 1,2-bis(trimethoxysilyl)ethane was dissolved in 1.5–1.7 parts by weight of anhydrous ethanol. After stirring for 4–6 min, 0.07–0.09 parts by weight of triethoxy-3-(2-imidazol-1-linyl)propane and 0.076–0.080 parts by weight of 3-aminopropyltriethoxysilane were added. The mixture was reacted at 45–55 °C for 1–2 h. Finally, the temperature was raised to 78–82 °C and the mixture was reacted for 55–65 min. The mixture was purified by centrifugation with anhydrous ethanol and deionized water 4–6 times. The resulting microspheres were then uniformly dispersed in 79–80 parts by weight of acetone and reacted at 70 °C for 11–13 h. After repeated centrifugation and washing with deionized water and anhydrous ethanol 5–7 times, a core-shell structured ion exchange resin was obtained.

[0030] By adopting the above technical solution, the present invention has the following beneficial effects:

[0031] (1) The lubricating oil filter material of the present invention comprises, from the outside to the inside, a coarse filter layer, a dehydration layer, and a fine filter layer. The dehydration layer includes a water-absorbing nanofiber membrane layer and a water-absorbing polyurethane layer attached to the surface of the nanofiber membrane layer, which increases the water absorption of the dehydration layer. The lubricating oil can be dehydrated at room temperature. When filtering the lubricating oil, it first passes through the coarse filter layer to intercept large solid particles, then passes through the dehydration layer for dehydration, and finally passes through the fine filter layer to intercept and filter the small solid particles remaining in the dehydrated lubricating oil. Thus, by using the lubricating oil filter material prepared by the present invention to filter the lubricating oil, solid particles in the lubricating oil can be effectively removed and water in the lubricating oil can be efficiently removed.

[0032] (2) The coarse filter layer of the present invention uses polyester fiber filter cloth with a pore size of 5 to 100 μm to intercept large solid particles.

[0033] (3) The water-absorbing nanofiber membrane of the present invention is obtained by mixing and spinning acrylic acid, acrylamide, ethyl bromide of 2-acrylate, citric acid-modified polyvinyl alcohol, and crosslinking agent glutaraldehyde. Citric acid-modified polyvinyl alcohol is used to form a branched structure with citric acid as the branching center and polyvinyl alcohol as the branch chain. At the same time, acrylic acid, acrylamide, and ethyl bromide of 2-acrylate are introduced to form an interpenetrating network structure of water-absorbing nanofiber membrane. While increasing the water absorption of the water-absorbing nanofiber membrane, the water resistance of the water-absorbing nanofiber membrane is effectively enhanced.

[0034] (4) The water-absorbing polyurethane layer of the present invention is obtained by reacting a core-shell structured ion exchange resin, isocyanate monomer, polyethylene glycol, and tris(3-hydroxypropyl)amine with an antioxidant. The hydroxyl groups on the amino groups, polyethylene glycol, and tris(3-hydroxypropyl)amine on the surface of the core-shell structured ion exchange resin react with the hydroxyl groups on the isocyanate monomer to form a branched structure of water-absorbing polyurethane with the core-shell structured ion exchange resin and tris(3-hydroxypropyl)amine as branching centers and polyethylene glycol urethane as branched chains. This structure is introduced into the cavity, which, while ensuring the water-absorbing polyurethane has good water absorption, can further filter solid particulate impurities in the lubricating oil and effectively improve the water resistance of the water-absorbing polyurethane layer. Furthermore, the introduction of the core-shell structured ion exchange resin into the water-absorbing polyurethane layer... The ester layer introduces adsorption sites to adsorb soluble paint films. Through the sulfonic acid groups in the core-shell structured ion exchange resin, hydrogen ion exchange removes metal cations and alkaline contaminants carried in the lubricating oil, as well as soluble paint films and precursors containing metal cations. Furthermore, the core-shell structured ion exchange resin creates a micro-nano protrusion hydrophilic structure on the surface of the water-absorbing polyurethane layer. When the dehydrated layer comes into contact with undehydrated lubricating oil, water is trapped within this micro-nano protrusion hydrophilic structure, forming a water film on the surface of the dehydrated layer. Utilizing the immiscibility of oil and water, the oil phase and water phase in the lubricating oil are separated, achieving dehydration and leaving no residue of the oil phase in the dehydrated layer. The introduction of antioxidants ensures that the lubricating oil is not easily oxidized during the filtration process.

[0035] (5) The shell-core structure ion exchange resin of the present invention is prepared by first using emulsion polymerization to prepare polystyrene microspheres, then sulfonating the polystyrene microspheres, and then using tetraethyl silicate to hydrolyze the surface of the sulfonated polystyrene microspheres to form a silica layer. Then, it is modified with 1,2-bistrimethoxysilyl ethane, triethoxy-3-(2-imidazol-1-linyl)propylsilane, and 3-aminopropyltriethoxysilane. The surfactant cetyltrimethylammonium bromide in the reaction process is further removed by solvent extraction to form a mesoporous silica shell layer, thus obtaining a shell-core structure ion exchange resin. The silica layer formed by the hydrolysis of triethoxy-3-(2-imidazol-1-linyl)propylsilane, 3-aminopropyltriethoxysilane, and 1,2-bistrimethoxysilyl ethane can effectively improve the hydrophilicity and dispersibility of the sulfonated polystyrene microspheres in the water-absorbing polyurethane layer.

[0036] (6) The fine filter layer of the present invention uses glass fiber filter paper with a precision of 0.5 to 20 μm; it further filters the dehydrated lubricating oil to intercept the small solid particles remaining in the dehydrated lubricating oil.

[0037] (7) In the preparation of the dehydration layer of the present invention, the water-absorbing nanofiber membrane layer is immersed in water-absorbing polyurethane to form a water-absorbing polyurethane layer on the surface of the water-absorbing nanofiber membrane layer. At the same time, the imidazole and tertiary amine in the polyurethane layer react with the bromoethane in the water-absorbing nanofiber membrane layer, consuming the hydrophobic bromoethane and forming hydrophilic imidazole salt and quaternary ammonium salt, which endow the dehydration layer with good antibacterial properties and further enhance the water absorption of the dehydration layer. Meanwhile, the water-absorbing polyurethane layer is firmly attached to the surface of the water-absorbing nanofiber membrane layer, which enhances the good water resistance of the dehydration layer. Furthermore, the introduction of imidazole salt and quaternary ammonium salt adsorbs anionic pollutants such as sulfate, chloride, organic acid anions and other acidic pollutants, and removes acidic oxides and organic acids carried in the oxidized and deteriorated lubricating oil.

[0038] (8) The lubricating oil filter material prepared by the present invention can also be used for the filtration and purification of gasoline, diesel and other organic liquid substances. Attached Figure Description

[0039] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0040] Figure 1 This is a schematic diagram of the structure of the lubricating oil filter material of the present invention.

[0041] The labels in the attached diagram are: coarse filter layer 1, dewatering layer 2, and fine filter layer 3. Detailed Implementation

[0042] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0044] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0045] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0046] In the description of the embodiments of the present invention, it should be understood that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of the present invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0047] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances. The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and should not be used to limit the scope of protection of the present invention.

[0048] The coarse filter layer 1 is made of polyester fiber filter cloth with a pore size of 5 to 100 μm;

[0049] The fine filter layer 3 uses glass fiber filter paper with a precision of 0.5 to 20 μm;

[0050] Polyvinyl alcohol: Type 17-88 polyvinyl alcohol is used;

[0051] The antioxidant used is antioxidant 1010.

[0052] (Example 1)

[0053] See Figure 1 A lubricating oil filter material, comprising, from the outside to the inside, a coarse filter layer 1, a dehydration layer 2, and a fine filter layer 3.

[0054] A method for preparing a lubricating oil filter material includes the following preparation steps:

[0055] S1. The water-absorbing nanofiber membrane layer is immersed in water-absorbing polyurethane for 5 minutes and then lifted vertically. It is then dried in an oven at 60°C for 23 hours and placed in a sealed environment for 2 days to obtain the dehydration layer 2.

[0056] S3. The coarse filter layer 1, the dehydration layer 2 obtained in step S1, and the fine filter layer 3 are stacked sequentially from the outside to the inside, and then folded into a continuous W shape to obtain the lubricating oil filter material.

[0057] The preparation steps of the water-absorbing nanofiber membrane are as follows:

[0058] A1. Mix 2 parts by mass of polyvinyl alcohol with 20 parts by mass of deionized water, heat to 88°C under stirring, and after the polyvinyl alcohol is completely dissolved in the deionized water, cool to the reaction temperature of 58°C. Then, add 18 parts by mass of 0.8 g / mL citric acid aqueous solution at a rate of 1 drop / s. After the addition is completed, keep warm for 3 hours, then stop stirring, add anhydrous ethanol as a precipitant to precipitate the product from the solution, filter, and then extract with anhydrous ethanol in a Soxhlet extractor for 11.5 hours. Dry under vacuum at 28°C to obtain citric acid modified polyvinyl alcohol. Mix 1 part by mass of citric acid modified polyvinyl alcohol with 9 parts by mass of deionized water, stir and heat to 90°C, continue stirring until the citric acid modified polyvinyl alcohol dissolves to obtain a 10% citric acid modified polyvinyl alcohol aqueous solution.

[0059] A2. Neutralize 3 parts by mass of acrylic acid with 20% sodium hydroxide solution in an ice-water bath, then add 1 part by mass of acrylamide at room temperature and mix well. Then add 0.07 parts by mass of emulsifier OP-10 and stir to disperse evenly. Next, add 0.1 parts by mass of ethyl bromide 2-acrylate and continue stirring to disperse evenly. Then add 7 parts by mass of 10% citric acid modified polyvinyl alcohol aqueous solution, 0.02 parts by mass of initiator potassium persulfate and 23 parts by mass of deionized water. Stir at 90 rpm for 25 min under nitrogen atmosphere and at 38°C. Then raise the temperature to 68°C and continue stirring for 55 min. Then raise the temperature to 78°C and stir at 130 rpm for 25 min. After the reaction is completed, keep stirring and cool down to 58°C. Add 0.18 parts by mass of 25% glutaraldehyde aqueous solution to obtain spinning solution.

[0060] A3. After ultrasonic treatment of the spinning solution for 25 minutes in an ultrasonic cleaner to remove bubbles, it was placed in an electrospinning machine and spun using tin foil as a collecting screen. After spinning, it was treated at 155℃ for 28 minutes and immediately placed in a vacuum preservation container for vacuum preservation to obtain a 0.18 mm thick water-absorbing nanofiber membrane layer.

[0061] The preparation steps of the water-absorbing polyurethane layer are as follows: 5 parts by mass of polyethylene glycol, 1.2 parts by mass of tris(3-hydroxypropyl)amine, and 50 parts by mass of N,N-dimethylacetamide are mixed, then heated to 58°C and stirred for 55 min. Then, 0.3 parts by mass of shell-core structured ion exchange resin are added and ultrasonically dispersed for 55 min. Next, 14 parts by mass of isophorone diisocyanate and 0.0002 parts by mass of catalyst dibutyltin dilaurate are added. The temperature is raised to 78°C and stirred for 4.5 h. Then, the temperature is lowered to 38°C, and 10% N,N-dimethylacetamide aqueous solution is added. The reaction continues for 23 h. After cooling to room temperature, 0.02 parts by mass of antioxidant is added and stirred to disperse evenly, resulting in a water-absorbing polyurethane layer with a solid content of 30%.

[0062] The preparation steps of the core-shell structured ion exchange resin are as follows:

[0063] (1) Dissolve 0.55 parts by mass of polyvinylpyrrolidone with an average molecular weight of 29,000 in 50 parts by mass of deionized water, then add 5.90 parts by mass of styrene, heat to 74°C and maintain under nitrogen atmosphere for 8 min, finally add initiator solution obtained by dissolving 0.14 parts by mass of potassium persulfate in 20 parts by mass of water, react for 23 h, centrifuge and wash twice with deionized water and anhydrous ethanol, and dry in a freeze dryer to obtain polystyrene microspheres;

[0064] (2) Under nitrogen protection, stirring and reflux, 0.15 parts by mass of polystyrene microspheres were slowly added to a mixed solution obtained by mixing 265 parts by mass of dichloromethane and 17 parts by mass of chlorosulfonic acid. Then, the sulfonation reaction was carried out at 55°C for 5 hours. After washing with deionized water until the pH was neutral, the microspheres were centrifuged and washed twice with anhydrous ethanol. Then, they were dried overnight in a freeze dryer to obtain sulfonated polystyrene microspheres.

[0065] (3) Take 0.2 parts by weight of sulfonated polystyrene microspheres, 60 parts by weight of deionized water, 15 parts by weight of anhydrous ethanol, 0.15 parts by weight of hexadecyl dimethyl ammonium bromide, and 0.65 parts by weight of 10% ammonia water, sonicate for 13 min, heat to 48°C, and stir continuously for 25 min. Then add 0.4 parts by weight of tetraethyl silicate and stir for 1.5 h. After that, add 2.3 parts by weight of ethanol solution containing 0.07 parts by weight of hexadecyl dimethyl ammonium bromide and 0.18 parts by weight of 10% ammonia water, stir for 0.4 h, and then add 0.2 parts by weight of 1,2- Di(trimethoxysilyl)ethane was dissolved in 1.5 parts by mass of anhydrous ethanol. After stirring for 4 min, 0.07 parts by mass of triethoxy-3-(2-imidazol-1-linyl)propanesilane and 0.076 parts by mass of 3-aminopropyltriethoxysilane were added. The mixture was reacted at 45 °C for 1 h. Finally, the temperature was raised to 78 °C and the mixture was reacted for 55 min. The mixture was purified by centrifugation with anhydrous ethanol and deionized water 4 times. The resulting microspheres were then uniformly dispersed in 79 parts by mass of acetone and reacted at 70 °C for 11 h. After repeated centrifugation and washing with deionized water and anhydrous ethanol 5 times, a core-shell structured ion exchange resin was obtained.

[0066] (Example 2)

[0067] See Figure 1 A lubricating oil filter material, comprising, from the outside to the inside, a coarse filter layer 1, a dehydration layer 2, and a fine filter layer 3.

[0068] A method for preparing a lubricating oil filter material includes the following preparation steps:

[0069] S1. The water-absorbing nanofiber membrane layer is immersed in water-absorbing polyurethane for 5 minutes and then lifted vertically. It is then dried in an oven at 60°C for 24 hours and placed in a sealed environment for 2 days to obtain the dehydration layer 2.

[0070] S3. The coarse filter layer 1, the dehydration layer 2 obtained in step S1, and the fine filter layer 3 are stacked sequentially from the outside to the inside, and then folded into a continuous W shape to obtain the lubricating oil filter material.

[0071] The preparation steps of the water-absorbing nanofiber membrane are as follows:

[0072] A1. Mix 2 parts by mass of polyvinyl alcohol with 20 parts by mass of deionized water, heat to 90°C under stirring, and after the polyvinyl alcohol is completely dissolved in the deionized water, cool to the reaction temperature of 60°C. Then, add 19 parts by mass of 0.875 g / mL citric acid aqueous solution at a rate of 1 drop / s. After the addition is completed, keep warm for 3 hours, then stop stirring, add anhydrous ethanol as a precipitant to precipitate the product from the solution, filter, and then extract with anhydrous ethanol in a Soxhlet extractor for 12 hours. Dry under vacuum at 30°C to obtain citric acid modified polyvinyl alcohol. Mix 1 part by mass of citric acid modified polyvinyl alcohol with 9 parts by mass of deionized water, stir and heat to 93°C, continue stirring until the citric acid modified polyvinyl alcohol dissolves to obtain a 10% citric acid modified polyvinyl alcohol aqueous solution.

[0073] A2. Neutralize 3 parts by mass of acrylic acid with 20% sodium hydroxide solution in an ice-water bath, then add 1.3 parts by mass of acrylamide at room temperature and mix well. Then add 0.08 parts by mass of emulsifier OP-10 and stir to disperse evenly. Next, add 0.2 parts by mass of ethyl bromide 2-acrylate and continue stirring to disperse evenly. Then add 7.5 parts by mass of 10% citric acid modified polyvinyl alcohol aqueous solution, 0.03 parts by mass of initiator potassium persulfate and 23.5 parts by mass of deionized water. Stir at 90 rpm for 30 min under nitrogen atmosphere and at 40°C. Then raise the temperature to 70°C and continue stirring for 60 min. Then raise the temperature to 80°C and stir at 135 rpm for 30 min. After the reaction is completed, keep stirring and cool down to 60°C. Add 0.19 parts by mass of 25% glutaraldehyde aqueous solution to obtain spinning solution.

[0074] A3. After ultrasonic treatment of the spinning solution for 30 minutes in an ultrasonic cleaner to remove bubbles, it was placed in an electrospinning machine and spun using tin foil as a collecting screen. After spinning, it was treated at 160℃ for 30 minutes and immediately placed in a vacuum preservation container for vacuum preservation to obtain a 0.19 mm thick water-absorbing nanofiber membrane layer.

[0075] The preparation steps of the water-absorbing polyurethane layer are as follows: 5 parts by mass of polyethylene glycol, 1.25 parts by mass of tris(3-hydroxypropyl)amine, and 52.5 parts by mass of N,N-dimethylacetamide are mixed, then heated to 60°C and stirred for 60 min. Then, 0.5 parts by mass of shell-core structured ion exchange resin are added, and the mixture is ultrasonically dispersed for 60 min. Next, 16 parts by mass of isophorone diisocyanate and 0.0003 parts by mass of catalyst dibutyltin dilaurate are added. The mixture is heated to 80°C and stirred for 5 h. Then, the temperature is lowered to 40°C, and 15% N,N-dimethylacetamide aqueous solution is added. The reaction continues for 24 h. After cooling to room temperature, 0.03 parts by mass of antioxidant is added, and the mixture is stirred and dispersed evenly to obtain a water-absorbing polyurethane layer with a solid content of 30%.

[0076] The preparation steps of the core-shell structured ion exchange resin are as follows:

[0077] (1) Dissolve 0.6 parts by mass of polyvinylpyrrolidone with an average molecular weight of 29,000 in 50 parts by mass of deionized water, then add 5.91 parts by mass of styrene, heat to 75°C and maintain under nitrogen atmosphere for 10 min, finally add initiator solution obtained by dissolving 0.15 parts by mass of potassium persulfate in 20 parts by mass of water, react for 24 h, centrifuge and wash 3 times with deionized water and anhydrous ethanol, and dry in a freeze dryer to obtain polystyrene microspheres;

[0078] (2) Under nitrogen protection, stirring and reflux, 0.2 parts by mass of polystyrene microspheres were slowly added to a mixed solution obtained by mixing 265.52 parts by mass of dichloromethane and 17.53 parts by mass of chlorosulfonic acid. Then, the sulfonation reaction was carried out at 60°C for 6 hours. After washing with deionized water until the pH was neutral, the microspheres were centrifuged and washed three times with anhydrous ethanol. Then, the microspheres were dried overnight in a freeze dryer to obtain sulfonated polystyrene microspheres.

[0079] (3) Take 0.2 parts by weight of sulfonated polystyrene microspheres, 60 parts by weight of deionized water, 15.78 parts by weight of anhydrous ethanol, 0.2 parts by weight of hexadecyl dimethyl ammonium bromide, and 0.67 parts by weight of 10% ammonia water, sonicate for 15 min, heat to 50°C, and stir continuously for 30 min. Then add 0.5 parts by weight of tetraethyl silicate and stir for 2 h. After that, add 2.37 parts by weight of ethanol solution containing 0.08 parts by weight of hexadecyl dimethyl ammonium bromide and 0.19 parts by weight of 10% ammonia water, stir for 0.5 h, and then add 0.25 parts by weight of 1,2-bis(trimethyl)methacrylate. Oxysilyl ethane was dissolved in 1.58 parts by mass of anhydrous ethanol. After stirring for 5 min, 0.08 parts by mass of triethoxy-3-(2-imidazol-1-linyl)propane and 0.078 parts by mass of 3-aminopropyltriethoxysilane were added. The mixture was reacted at 50 °C for 1.5 h, and then the temperature was raised to 80 °C for 1 h. The mixture was purified by centrifugation five times with anhydrous ethanol and deionized water. The resulting microspheres were then uniformly dispersed in 79.1 parts by mass of acetone and reacted at 70 °C for 12 h. After repeated centrifugation and washing with deionized water and anhydrous ethanol six times, the mixture was stirred and mixed evenly to obtain a core-shell structured ion exchange resin.

[0080] (Example 3)

[0081] See Figure 1 A lubricating oil filter material, comprising, from the outside to the inside, a coarse filter layer 1, a dehydration layer 2, and a fine filter layer 3.

[0082] A method for preparing a lubricating oil filter material includes the following preparation steps:

[0083] S1. The water-absorbing nanofiber membrane layer is immersed in water-absorbing polyurethane for 5 minutes and then lifted vertically. It is then dried in an oven at 60°C for 25 hours and placed in a sealed environment for 2 days to obtain the dehydration layer 2.

[0084] S3. The coarse filter layer 1, the dehydration layer 2 obtained in step S1, and the fine filter layer 3 are stacked sequentially from the outside to the inside, and then folded into a continuous W shape to obtain the lubricating oil filter material.

[0085] The preparation steps of the water-absorbing nanofiber membrane are as follows:

[0086] A1. Mix 2 parts by mass of polyvinyl alcohol with 20 parts by mass of deionized water, heat to 92°C under stirring, and after the polyvinyl alcohol is completely dissolved in the deionized water, cool to the reaction temperature of 62°C. Then, add 20 parts by mass of 0.9 g / mL citric acid aqueous solution at a rate of 1 drop / s. After the addition is completed, keep warm for 3 hours, then stop stirring, add anhydrous ethanol as a precipitant to precipitate the product from the solution, filter, and then extract with anhydrous ethanol in a Soxhlet extractor for 12.5 hours. Dry under vacuum at 32°C to obtain citric acid modified polyvinyl alcohol. Mix 1 part by mass of citric acid modified polyvinyl alcohol with 9 parts by mass of deionized water, stir and heat to 95°C, continue stirring until the citric acid modified polyvinyl alcohol is dissolved to obtain a 10% citric acid modified polyvinyl alcohol aqueous solution.

[0087] A2. Neutralize 3 parts by mass of acrylic acid with 20% sodium hydroxide solution in an ice-water bath, then add 1.5 parts by mass of acrylamide at room temperature and mix well. Then add 0.09 parts by mass of emulsifier OP-10 and stir to disperse evenly. Next, add 0.3 parts by mass of ethyl bromide 2-acrylate and continue stirring to disperse evenly. Then add 8 parts by mass of 10% citric acid modified polyvinyl alcohol aqueous solution, 0.04 parts by mass of initiator potassium persulfate and 24 parts by mass of deionized water. Stir at 90 rpm for 35 min under nitrogen atmosphere and at 42°C. Then raise the temperature to 72°C and continue stirring for 65 min. Then raise the temperature to 82°C and stir at 140 rpm for 35 min. After the reaction is completed, keep stirring and cool down to 62°C. Add 0.20 parts by mass of 25% glutaraldehyde aqueous solution to obtain spinning solution.

[0088] A3. After ultrasonic treatment of the spinning solution for 30 minutes in an ultrasonic cleaner to remove bubbles, it was placed in an electrospinning machine and spun using tin foil as a collecting screen. After spinning, it was treated at 160℃ for 32 minutes and immediately placed in a vacuum preservation container for vacuum preservation to obtain a 0.22 mm thick water-absorbing nanofiber membrane layer.

[0089] The preparation steps of the water-absorbing polyurethane layer are as follows: 5 parts by mass of polyethylene glycol, 1.3 parts by mass of tris(3-hydroxypropyl)amine, and 55 parts by mass of N,N-dimethylacetamide are mixed, then heated to 62°C and stirred for 65 min. Then, 0.8 parts by mass of shell-core structured ion exchange resin are added and ultrasonically dispersed for 65 min. Next, 18 parts by mass of isophorone diisocyanate and 0.0004 parts by mass of catalyst dibutyltin dilaurate are added. The temperature is raised to 82°C and stirred for 5.5 h. Then, the temperature is lowered to 42°C, and 20% N,N-dimethylacetamide aqueous solution is added. The reaction continues for 25 h. After cooling to room temperature, 0.04 parts by mass of antioxidant is added and stirred to disperse evenly, resulting in a water-absorbing polyurethane layer with a solid content of 30%.

[0090] The preparation steps of the core-shell structured ion exchange resin are as follows:

[0091] (1) Dissolve 0.65 parts by mass of polyvinylpyrrolidone with an average molecular weight of 29,000 in 50 parts by mass of deionized water, then add 5.92 parts by mass of styrene, heat to 76°C and maintain under nitrogen atmosphere for 12 min, finally add initiator solution obtained by dissolving 0.16 parts by mass of potassium persulfate in 20 parts by mass of water, react for 25 h, centrifuge and wash 4 times with deionized water and anhydrous ethanol, and dry in a freeze dryer to obtain polystyrene microspheres;

[0092] (2) Under nitrogen protection, stirring and reflux, 0.25 parts by mass of polystyrene microspheres were slowly added to a mixed solution obtained by mixing 266 parts by mass of dichloromethane and 18 parts by mass of chlorosulfonic acid. Then, the sulfonation reaction was carried out at 65°C for 7 hours. After washing with deionized water until the pH was neutral, the microspheres were centrifuged and washed 4 times with anhydrous ethanol. Then, the microspheres were dried overnight in a freeze dryer to obtain sulfonated polystyrene microspheres.

[0093] (3) 0.2 parts by weight of sulfonated polystyrene microspheres, 60 parts by weight of deionized water, 16 parts by weight of anhydrous ethanol, 0.25 parts by weight of hexadecyl dimethyl ammonium bromide, and 0.69 parts by weight of 10% ammonia water were ultrasonically vibrated for 17 min, then heated to 52°C and stirred continuously for 35 min. Then, 0.6 parts by weight of tetraethyl silicate were added and the mixture was stirred for 2.5 h. Afterward, 2.4 parts by weight of an ethanol solution containing 0.09 parts by weight of hexadecyl dimethyl ammonium bromide and 0.20 parts by weight of 10% ammonia water were added, and the mixture was stirred for 0.6 h. Finally, 0.3 parts by weight of 1,2- A solution of bis(trimethoxysilyl)ethane was dissolved in 1.7 parts by mass of anhydrous ethanol. After stirring for 6 min, 0.09 parts by mass of triethoxy-3-(2-imidazol-1-linyl)propane and 0.080 parts by mass of 3-aminopropyltriethoxysilane were added. The mixture was reacted at 55 °C for 2 h. Finally, the temperature was raised to 82 °C and the mixture was reacted for 65 min. The mixture was purified by centrifugation with anhydrous ethanol and deionized water 6 times. The resulting microspheres were then uniformly dispersed in 80 parts by mass of acetone and reacted at 70 °C for 13 h. After repeated centrifugation and washing with deionized water and anhydrous ethanol 7 times, a core-shell structured ion exchange resin was obtained.

[0094] (Comparative Example 1)

[0095] The difference between Comparative Example 1 and Example 2 is that the dehydration layer is made of only a water-absorbing nanofiber membrane layer, rather than a combination of a water-absorbing nanofiber membrane layer and a water-absorbing polyurethane layer attached to the surface of the nanofiber membrane layer. The other components and steps are the same as in Example 2.

[0096] (Comparative Example 2)

[0097] The difference between Comparative Example 2 and Example 2 is that the water-absorbing nanofiber membrane is obtained by mixing and spinning acrylic acid, acrylamide, ethyl bromide 2-acrylate, polyvinyl alcohol, and crosslinking agent glutaraldehyde. The remaining components and steps are the same as in Example 2.

[0098] (Comparative Example 3)

[0099] The difference between Comparative Example 3 and Example 2 is that the water-absorbing polyurethane layer is obtained by reacting sulfonated polystyrene microspheres, isocyanate monomers, polyethylene glycol, tris(3-hydroxypropyl)amine and an antioxidant. The remaining components and steps are the same as in Example 2.

[0100] (Comparative Example 4)

[0101] The difference between Comparative Example 4 and Example 2 is that the water-absorbing polyurethane layer is obtained by reacting isocyanate monomer, polyethylene glycol, tris(3-hydroxypropyl)amine and then compounding it with an antioxidant. The remaining components and steps are the same as in Example 2.

[0102] (Comparative Example 5)

[0103] The difference between Comparative Example 5 and Example 2 is that the water-absorbing polyurethane layer is obtained by reacting a core-shell structured ion exchange resin, isocyanate monomer, and polyethylene glycol with an antioxidant. The remaining components and steps are the same as in Example 2.

[0104] (Example of the effect)

[0105] Oil-water separation efficiency: Hexane and water were mixed in a 1:1 volume ratio, with the water dyed methylene blue and the hexane dyed oil red O. Two identical glass instruments with flange base openings on one side were placed together. 1 g of the dehydration layer prepared in the examples and comparative examples was placed between the flange bases of the two glass instruments, and the two glass instruments with flange base openings and the dehydration layer were fixed together with clamps. 40 mL of the oil-water mixture was poured into the glass instrument from above. The mass of the filtered hexane was recorded as C1. Oil-water separation efficiency = C1 / mass of the filtered oil-water mixture.

[0106] Water absorption capacity test: The dehydration layer prepared in Examples 1-3 and Comparative Examples 1-5 of the present invention was weighed and recorded as m0. It was then immersed in 1000 times its mass of deionized water. After the adsorption was saturated, it was taken out and weighed, and the mass was recorded as m1. Water absorption capacity C0 = (m1-m0) / m0.

[0107] Breakthrough force and water resistance test: Take two identical glass instruments with flange base openings on one side, place them with the base openings joined together, then place the dehydration layer in the middle of the flange bases of the two glass instruments, and fix the two glass instruments with flange base openings and the dehydration layer together with clamps; slowly pour n-hexane into the upper glass tube; record the height of n-hexane at the top when n-hexane flows from the upper glass tube into the lower glass tube, which is the maximum n-hexane height that the polyurethane hydrogel oil-water separation membrane can withstand; calculate the breakthrough pressure using the following formula: breakthrough pressure p = ρgh; where ρ is the density of n-hexane, g is the gravitational acceleration, and h is the maximum n-hexane height; immerse the dehydration layer in water for 7 days, then remove it and measure the breakthrough force.

[0108] Acid removal capacity: Take two identical glass instruments with flange base openings on one side, place them together, and then make filter elements from 1g of the lubricating oil filter material prepared in the examples and comparative examples. Install the filter elements into the filter and circulate and filter 40mL of 46# waste ashless anti-wear lubricating oil with an acid value of 1.51mg potassium hydroxide / g three times. Measure the acid value of the filtered waste ashless anti-wear lubricating oil according to GB / T7304-2014.

[0109] Table 1 below shows the performance data of the dehydration layers obtained in Examples 1-3 and Comparative Examples 1-5 of this invention:

[0110] Table 1

[0111]

[0112]

[0113] As shown in Table 1 above, the dehydration layers prepared in Examples 1 to 3 have good water absorption, high oil-water separation efficiency, and good resistance to water and removal of acidic substances.

[0114] The difference between Comparative Example 1 and Example 2 is that the dehydration layer only uses a water-absorbing nanofiber membrane layer, instead of being a combination of a water-absorbing nanofiber membrane layer and a water-absorbing polyurethane layer attached to the surface of the nanofiber membrane layer. The resulting dehydration layer has poor water absorption, low oil-water separation efficiency, and poor water resistance and acid removal ability.

[0115] The difference between Comparative Example 2 and Example 2 is that the water-absorbing nanofiber membrane is obtained by mixing and spinning acrylic acid, acrylamide, ethyl bromide 2-acrylate, polyvinyl alcohol, and crosslinking agent glutaraldehyde, without modifying polyvinyl alcohol with citric acid. As a result, the water absorption and water resistance of the dehydrating layer are weaker.

[0116] The difference between Comparative Example 3 and Example 2 is that the water-absorbing polyurethane layer is obtained by reacting sulfonated polystyrene microspheres, isocyanate monomers, polyethylene glycol, tris(3-hydroxypropyl)amine and an antioxidant. The sulfonated polystyrene microspheres were not modified, resulting in a dehydrating layer with weaker water absorption, water resistance, and acid removal ability.

[0117] The difference between Comparative Example 4 and Example 2 is that the water-absorbing polyurethane layer is obtained by reacting isocyanate monomer, polyethylene glycol, tris(3-hydroxypropyl)amine and then compounding it with an antioxidant. No core-shell structure ion exchange resin was added. The resulting dehydration layer has weaker water absorption, water resistance and acid removal ability.

[0118] The difference between Comparative Example 5 and Example 2 is that the water-absorbing polyurethane layer is obtained by reacting a core-shell structure ion exchange resin, isocyanate monomer, polyethylene glycol and an antioxidant, without adding tri(3-hydroxypropyl)amine for the reaction. The resulting dehydrating layer has weaker water absorption, water resistance and acid removal ability.

[0119] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A lubricating oil filtration material, characterized by, From outside to inside, it includes coarse filter layer (1), dehydration layer (2), fine filter layer (3) in turn; the dehydration layer includes water absorption nanofiber membrane layer and water absorption polyurethane layer attached to the surface of the nanofiber membrane layer; The water absorption polyurethane layer is obtained by compounding the antioxidant with the reaction product of the shell-core structure ion exchange resin, isocyanate monomer, polyethylene glycol and tris(3-hydroxypropyl)amine; The shell-core structure ion exchange resin is prepared by first adopting emulsion polymerization to prepare polystyrene microspheres, then sulfonating the polystyrene microspheres, then using tetraethyl silicate to perform hydrolysis reaction on the surface of the sulfonated polystyrene microspheres to form a silica layer, then using 1,2-bistrimethoxysilylethane, triethoxy-3-(2-imidazol-1-yl)propane silane and 3-aminopropyl triethoxysilane for modification, and further using solvent extraction method to remove the surfactant cetyltrimethylammonium bromide in the reaction process to form a mesoporous silica shell layer, thereby obtaining the shell-core structure ion exchange resin.

2. The lubricating oil filtration material of claim 1, wherein, The coarse filter layer (1) adopts polyester fiber filter cloth with a pore size of 5-100 mu m; the fine filter layer (3) adopts glass fiber filter paper with a precision of 0.5-20 mu m.

3. The lubricating oil filtration material of claim 1, wherein, The water absorption nanofiber membrane layer is obtained by mixing reaction of acrylic acid, acrylamide, 2-bromoethyl acrylate, citric acid modified polyvinyl alcohol and crosslinking agent glutaraldehyde and spinning.

4. The lubricating oil filtration material of claim 1, wherein, The lubricating oil filtering material can also be used for filtering and purifying gasoline, diesel oil and other organic liquid substances.

5. A method of preparing a lubricating oil filter material as claimed in any one of claims 1 to 4, characterised in that, The preparation steps include: S1. Soak the water absorption nanofiber membrane layer in the water absorption polyurethane for 4-6 min, then vertically pull up, then bake in an oven at 60 DEG C for 23-25 h, and then place in a sealed environment for 2 days to obtain the dehydration layer (2); S3. Stack the coarse filter layer (1), the dehydration layer (2) prepared in step S1 and the fine filter layer (3) in turn from outside to inside, then fold into a continuous W shape to obtain the lubricating oil filtering material.

6. The method of making a lubricating oil filtration material according to claim 5, wherein, The preparation steps of the water absorption nanofiber membrane layer are as follows: A1. Mix 2 parts by mass of polyvinyl alcohol with 20 parts by mass of deionized water, heat to 88-92 DEG C under stirring, then cool to a reaction temperature of 58-62 DEG C, then add 18-20 parts by mass of 0.8-0.9 g / mL citric acid aqueous solution at a rate of 1 drop / s, keep warm for 3 h after the addition is completed, then stop stirring, add anhydrous ethanol as a settling agent to precipitate the product from the solution, then perform suction filtration, then extract with anhydrous ethanol in a Soxhlet extractor for 11.5-12.5 h, and then dry under vacuum at 28-32 DEG C to obtain citric acid modified polyvinyl alcohol; mix 1 part by mass of citric acid modified polyvinyl alcohol with 9 parts by mass of deionized water, stir and heat to 90-95 DEG C, continue to stir until the citric acid modified polyvinyl alcohol is dissolved to obtain a 10% citric acid modified polyvinyl alcohol aqueous solution; A2. In an ice water bath, 3 parts by mass of acrylic acid is neutralized with a 20% sodium hydroxide solution, 1-1.5 parts by mass of acrylamide is added at room temperature, and mixed uniformly, then 0.07-0.09 parts by mass of an emulsifier is added and stirred to disperse uniformly, followed by the addition of 0.1-0.3 parts by mass of 2-bromoethyl acrylate, and continued stirring and dispersion, then 7-8 parts by mass of a 10% citric acid modified polyvinyl alcohol aqueous solution, 0.02-0.04 parts by mass of an initiator potassium persulfate, and 23-24 parts by mass of deionized water are added, and stirred at 90 rpm for 25-35 min under a nitrogen atmosphere and at 38-42°C, then the temperature is raised to 68-72°C, and continued stirring for 55-65 min, then the temperature is raised to 78-82°C, and stirred at 130-140 rpm for 25-35 min, after the reaction is completed, the stirring is maintained and the temperature is lowered to 58-62°C, 0.18-0.20 parts by mass of a 25% glutaraldehyde aqueous solution is added, and a spinning solution is obtained; A3. The spinning solution is de-aerated by ultrasonic treatment for 25-30 min using an ultrasonic cleaner, and then spun into a nanofiber membrane layer using a static spinning machine with tin foil as a collection screen, and the nanofiber membrane layer is treated at 155-160°C for 28-32 min after spinning, immediately placed in a vacuum preservation barrel to preserve under vacuum, and a water-absorbing nanofiber membrane layer is obtained.

7. The method of making a lubricating oil filtration material of claim 5, wherein, The preparation steps of the water-absorbing polyurethane layer are as follows: 5 parts by mass of polyethylene glycol, 1.2-1.3 parts by mass of tris(3-hydroxypropyl)amine, and 50-55 parts by mass of N,N-dimethylacetamide are mixed, and then the temperature is raised to 58-62°C and stirred for 55-65 min, then 0.3-0.8 parts by mass of a core-shell structure ion exchange resin is added and ultrasonically dispersed for 55-65 min, then 14-18 parts by mass of isophorone diisocyanate and 0.0002-0.0004 parts by mass of a catalyst dibutyltin dilaurate are added, the temperature is raised to 78-82°C, and stirred for 4.5-5.5 h, then the temperature is lowered to 38-42°C, 10-20% N,N-dimethylacetamide aqueous solution is added, and the reaction is continued for 23-25 h, then the temperature is lowered to room temperature, and 0.02-0.04 parts by mass of an antioxidant is added, and a water-absorbing polyurethane layer with a solid content of 20-40% is obtained.

8. The method of making a lubricating oil filtration material according to claim 7, wherein, The preparation steps of the core-shell structure ion exchange resin are as follows: (1) 0.55-0.65 parts by mass of polyvinylpyrrolidone is dissolved in 50 parts by mass of deionized water, 5.90-5.92 parts by mass of styrene is added, heated to 74-76°C, and maintained under a nitrogen atmosphere for 8-12 min, and finally an initiator solution obtained by dissolving 0.14-0.16 parts by mass of potassium persulfate in 20 parts by mass of water is added, and the reaction is continued for 23-25 h, centrifugal washing is performed 2-4 times with deionized water and anhydrous ethanol, and drying is performed in a freeze dryer, and polystyrene microspheres are obtained; (2) under the conditions of nitrogen protection, stirring and reflux condensation, 0.15-0.25 mass parts of polystyrene microspheres are slowly added into a mixed solution obtained by mixing 265-266 mass parts of dichloromethane and 17-18 mass parts of chlorosulfonic acid, and then a sulfonation reaction is carried out at 55-65℃ for 5-7h, and then washed with deionized water until the pH is neutral, followed by centrifugation and washing with anhydrous ethanol for 2-4 times, and then dried in a freeze dryer overnight to obtain sulfonated polystyrene microspheres; (3) 0.2 mass parts of sulfonated polystyrene microspheres, 60 mass parts of deionized water, 15-16 mass parts of anhydrous ethanol, 0.15-0.25 mass parts of cetyl dimethyl ammonium bromide, 0.65-0.69 mass parts of 10% ammonia water, are ultrasonically oscillated for 13-17 min, and then heated to 48-52℃, and continuously stirred for 25-35 min, and then 0.4-0.6 mass parts of tetraethyl silicate is added and stirred for 1.5-2.5h, and then 2.3-2.4 mass parts of an ethanol solution containing 0.07-0.09 mass parts of cetyl dimethyl ammonium bromide and 0.18-0.20 mass parts of 10% ammonia water is added, and stirred for 0.4-0.6h, and then a solution of 0.2-0.3 mass parts of 1,2-bistrimethoxysilyl ethane in 1.5-1.7 mass parts of anhydrous ethanol is added, and stirred for 4-6 min, and then 0.07-0.09 mass parts of triethoxy-3-(2-imidazole-1-yl) propane silane and 0.076-0.080 mass parts of 3-aminopropyl triethoxysilane are added, and reacted at 45-55℃ for 1-2h, and finally the temperature is raised to 78-82℃ and reacted for 55-65 min, and then purified by centrifugation with anhydrous ethanol and deionized water for 4-6 times, and then the obtained microspheres are uniformly dispersed in 79-80 mass parts of acetone, and reacted at 70℃ for 11-13h, and then washed repeatedly by centrifugation with deionized water and anhydrous ethanol for 5-7 times to obtain a core-shell structure ion exchange resin.

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