Composite lubricating oil and preparation method thereof

Abstract

The invention provides compound lubricating oil and a preparation method thereof, and relates to the technical field of lubricating oil. The composite lubricating oil comprises the following raw material components in percentage by weight: 90-95% of base oil, 0.5-1.5% of nano aluminum oxide, 0.2-1% of nano silicon dioxide and 2-10% of an organic functional additive, the nano aluminum oxide and the nano silicon dioxide are independently subjected to surface treatment by adopting a polyether silane coupling agent. The polyether chain segments are chemically bonded on the surfaces of the nano aluminum oxide and the nano silicon dioxide, so that the compatibility of the nano aluminum oxide and the nano silicon dioxide with the base oil is improved, and the nano aluminum oxide and the nano silicon dioxide can play a better role.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of lubricating oil, and relates to a composite lubricating oil and a preparation method thereof. BACKGROUND

[0002] Nanometer aluminum oxide and nanometer silicon dioxide are commonly used nanometer functional additives in lubricating oil. Nanometer aluminum oxide has the characteristics of high hardness, high temperature resistance, and good heat conduction, and mainly plays the roles of "anti-wear strengthening", "high temperature stability", and rapid heat conduction in lubricating oil. Nanometer silicon dioxide can fill the micro-pits on the friction surface, reduce the surface roughness, and assist in reducing friction and wear. However, the unmodified nanometer aluminum oxide and nanometer silicon dioxide have poor compatibility with the base oil of lubricating oil, are prone to agglomeration and failure, and even cause more adverse consequences, such as aggravating wear. Therefore, the surface treatment of nanometer aluminum oxide and nanometer silicon dioxide is very important in lubricating oil, which not only needs to have good compatibility with the base oil, but also needs to have good high temperature resistance, good oxidation stability, good hydrolysis resistance, and good load resistance, so as to adapt to the working environment of lubricating oil. The prior art generally uses silane coupling agent or titanate coupling agent as a surface treatment agent to treat the surface of nanometer aluminum oxide and / or nanometer silicon dioxide, so as to improve the compatibility of nanometer aluminum oxide and / or nanometer silicon dioxide with the base oil.

[0003] However, in view of the compatibility of the organic structure on the silane coupling agent or the titanate coupling agent with the base oil and the effect on the dispersion of nanometer aluminum oxide and / or nanometer silicon dioxide, the applicant believes that the surface treatment technology of nanometer aluminum oxide and nanometer silicon dioxide still needs to be further optimized. SUMMARY

[0004] In order to solve the above technical problems, the present application provides a composite lubricating oil and a preparation method thereof.

[0005] The technical scheme of the present application is as follows:

[0006] A composite lubricating oil, the raw material components are 90-95% base oil, 0.5-1.5% nanometer aluminum oxide, 0.2-1% nanometer silicon dioxide, and 2-10% organic functional additive, by weight of 100%;

[0007] The nanometer aluminum oxide and the nanometer silicon dioxide are independently surface treated by a polyether silane coupling agent;

[0008] The structural formula of the polyether silane coupling agent is shown in the following formula (1),

[0009] R 1 -Z-(CH2)3R 2 x Si(OR 3 ) 3-x (1)

[0010] wherein R 1 selected from C1-C12 alkyl, R 2 and R 3 individually selected from C1-C4 alkyl, Z represents a polyether segment, x = 0-1.

[0011] Preferably, the polyether segment consists of at least one of a polyethylene glycol segment, a polypropylene glycol segment, and a polytetrahydrofuran ether glycol segment.

[0012] The molar content of the polyethylene glycol segment in the polyether segment is not more than 20%.

[0013] Preferably, the molar content of the polytetrahydrofuran ether glycol segment in the polyether segment is not less than 50%.

[0014] Preferably, the number average molecular weight of the polyether segment is 100-1000.

[0015] Preferably, the average particle size of the nano-aluminum is set as a, the average particle size of the nano-silica is set as b, then:

[0016] a = 10-100 nm, b = 10-50 nm, b = (0.15-0.5)a.

[0017] More preferably, the values of a and b satisfy: b = (0.25-0.5)a.

[0018] Preferably, the organic functional additive is selected from one or a combination of two or more of an antioxidant, an extreme pressure anti-wear agent, a dispersant, a rust inhibitor, an antifoaming agent, and a pour point depressant.

[0019] More preferably, the weight percentage of the antioxidant in the raw material component is 0.5-1%;

[0020] The weight percentage of the extreme pressure anti-wear agent in the raw material component is 1.5-3%;

[0021] The weight percentage of the dispersant in the raw material component is 0.5-2%;

[0022] The weight percentage of the rust inhibitor in the raw material component is 0.1-0.5%;

[0023] The weight percentage of the antifoaming agent in the raw material component is 0.001-0.01%;

[0024] The weight percentage of the pour point depressant in the raw material component is 0.5-1.5%.

[0025] More preferably, the dispersant is selected from a polyether fatty acid ester.

[0026] The structural formula of the polyether fatty acid ester is shown in the following formula (2),

[0027] R 4 -COO(CH2CH2O) y (CH2CH3CHO) z R 5 (2)

[0028] wherein R 4 is a C6-C24 alkyl group, R 5 is selected from H or methyl, y≥0, z≥0, 3≤y+z≤12.

[0029] A preparation method of the composite lubricating oil described in any one of the above embodiments, the base oil is heated to 80-120℃, the nano-alumina and the nano-silica are added, ultrasonic dispersion is uniform, the organic functional additive is continuously added, stirring dispersion is uniform, and the temperature is reduced to not more than 40℃, and the composite lubricating oil is obtained.

[0030] The beneficial effects of the present application are:

[0031] (1) The polyether silane coupling agent is used for surface treatment of the nano-alumina and the nano-silica respectively, the polyether chain segments introduced on the surfaces of the nano-alumina and the nano-silica have good compatibility with the base oil of the lubricating oil, so that the nano-alumina and the nano-silica can be well dispersed in the base oil, and the polyether chain segments have the characteristics of hydrolysis resistance, high temperature resistance, and good load resistance, which are suitable for the working environment of the lubricating oil.

[0032] (2) The average particle size of the nano-alumina and the nano-silica is within a certain range, which can play the effects of wear resistance strengthening, temperature resistance improvement, and heat conduction of the nano-alumina, and the effects of lubrication improvement and friction reduction of the nano-silica, and the "softer" nano-silica can be well filled in the gap between the "harder" nano-alumina particles, which can play a buffering role when the nano-alumina is subjected to pressure, and synergistically play the effects, thereby further improving the performance of the composite lubricating oil.

[0033] (3) The polyether fatty acid ester with certain amphiphilicity is used as a dispersant, so that the surface-treated nano-alumina and nano-silica can be suitable for different polarity base oils, and the lubricating oil formula is more flexible. In addition, even if the polyether chain segments grafted on the surfaces of the nano-alumina and the nano-silica are broken and / or fall off after long-term work, the broken polyether still has certain amphiphilicity, and the broken polyether and the polyether fatty acid ester can synergistically play the role of the dispersant, and still maintain the good dispersibility of the nano-alumina and the nano-silica in the lubricating oil. DETAILED DESCRIPTION

[0034] The technical solution of the present invention will be further explained and described below through specific embodiments.

[0035] On the one hand, the present invention proposes a composite lubricating oil, wherein the raw material components, by weight, include: 90-95% base oil, 0.5-1.5% nano alumina, 0.2-1% nano silica and 2-10% organic functional additives;

[0036] Nano-alumina and nano-silica are individually surface-treated using polyether silane coupling agents;

[0037] The structural formula of the above-mentioned polyether silane coupling agent is shown in formula (1) below.

[0038] R 1 -Z-(CH2)3R 2 x Si(OR 3 ) 3-x (1)

[0039] Among them, R 1 Selected from C1-C12 alkyl groups, R 2 and R 3 The individual components are selected from C1-C4 alkyl groups, Z represents the polyether segment, and x = 0-1.

[0040] This invention utilizes a polyether silane coupling agent to chemically bond the organic structure -(CH2)3-ZR onto the surfaces of nano-alumina and nano-silica. 1 This improved the compatibility of nano-alumina and nano-silica with base oils, and achieved good dispersibility of nano-alumina and nano-silica in base oils.

[0041] For the above-mentioned polyether silane coupling agent, it can be made from alkenyl polyether CH2=CHCH2-ZR 1 With hydrogen-containing silanes HR 2 x Si(OR 3 ) 3-x It is obtained by hydrosilylation reaction. Specifically, one preparation method is as follows: an alkenyl polyether and a hydrosilane are added to a reaction vessel in a molar ratio of 1:1-1.2, the temperature is raised to 80°C, a hydrosilylation catalyst (such as Karstedt catalyst, the amount is 10-50 ppm based on Pt) is added, and the reaction is kept at 130-140°C until the terminal alkenyl group disappears (which can be detected by FT-IR), and unreacted hydrosilane (if present) is removed to obtain the polyether silane coupling agent.

[0042] There are no particular limitations on the surface treatment process of nano-alumina and nano-silica using polyether silane coupling agents; existing technologies can be referenced. Taking the surface treatment of nano-alumina as an example, one method is as follows: Disperse 1-10 parts by weight of nano-alumina into 100 parts by weight of a mixed solvent composed of anhydrous ethanol and water in a volume ratio of 7:3-9:1, adjust the pH to 3-5, add a polyether silane coupling agent (the weight of the polyether silane coupling agent can be 5%-20% of the weight of the nano-alumina), stir at room temperature for 1-2 hours, heat to micro-reflux, continue the reaction for 2-5 hours, cool down, collect the solid particles, wash 2-3 times with anhydrous ethanol, and dry at 50-70℃ to obtain polyether-treated nano-alumina.

[0043] In some embodiments, the polyether segment is composed of at least one of the following: polyethylene glycol segment EO (-CH2CH2O-), polypropylene glycol segment PO (-CH2CH3CHO-), and polytetrahydrofuran ether glycol segment TO (-CH2CH2CH2CH2O-).

[0044] The molar content of polyethylene glycol (EO) segments in the polyether segments does not exceed 20%.

[0045] The water content of lubricating oil gradually increases during operation. Among EO, PO, and TO, the polarity decreases in that order. EO has higher polarity, better hydrophilicity, but slightly lower heat resistance. The molar content of EO in the polyether segment should not exceed 20%, which can improve the heat resistance, stability, and water incompatibility of the polyether segment. For example, the molar content of EO in the polyether segment can be any value from 20%, 15%, 10%, 5%, 0, etc., or any value in between, without particular restrictions.

[0046] In some embodiments, the molar content of the polytetrahydrofuran ether diol (TO) segment in the polyether segment is not less than 50%. TO has good heat resistance, stability, and hydrophobicity. Further, the molar content of TO in the polyether segment does not exceed 80%, for example, it can be any value or any value between 50%, 55%, 60%, 65%, 70%, 75%, 80%, etc., without particular limitation. Further, the polyether segment is composed of two or three of EO, PO, and TO, which can constitute a polyether segment with a certain degree of amphiphilicity, suitable for base oils of different polarities. Therefore, in this invention, there are no particular limitations on the base oil; it can be a synthetic base oil (such as polyalphaolefin oil, ester oil) and / or a mineral base oil.

[0047] In some embodiments, the number average molecular weight of the polyether segments is 100-1000. For example, the number average molecular weight can be any value or any value between 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, etc., without any particular limitation.

[0048] In some embodiments, the average particle size of nano-alumina is set as a, and the average particle size of nano-silica is set as b, then:

[0049] a = 10-100nm, b = 10-50nm, b = (0.15-0.5)a. For example, b = 0.15a, or b = 0.2a, or b = 0.25a, ​​or b = 0.3a, or b = 0.35a, or b = 0.4a, or b = 0.45a, or b = 0.5a, etc. For example, if a is 60nm, b can be 10nm, 15nm, 20nm, 30nm, etc.

[0050] The "harder" nano-alumina provides anti-wear, anti-pressure, and high-temperature resistance, while the "softer" nano-silica provides lubrication. By setting the particle size of the two nanomaterials within the aforementioned range, the "softer" nano-silica can also buffer the "harder" nano-alumina, working synergistically to further enhance the performance of the composite lubricant.

[0051] Furthermore, the values ​​of a and b satisfy: b = (0.25 - 0.5)a.

[0052] The "harder" nano-alumina provides anti-wear, anti-pressure, and high-temperature resistance, while the "softer" nano-silica provides lubrication. By setting the particle size of the two nanomaterials within the aforementioned range, the "softer" nano-silica can also buffer the "harder" nano-alumina, working synergistically to further improve the performance of the composite lubricant, especially its anti-wear properties.

[0053] In some embodiments, the organic functional additive is selected from one or a combination of two or more of antioxidants, extreme pressure anti-wear agents, dispersants, rust inhibitors, defoamers, and pour point depressants.

[0054] Furthermore, the antioxidant accounts for 0.5-1% of the weight of the raw material components; for example, the antioxidant can be zinc thiophosphoric acid alkylphenol salt, zinc primary and secondary thiophosphoric acid alkyl salt, zinc dialkyl dithiophosphate, 2,6-di-tert-butyl mixed phenol, 2,6-di-tert-butyl-p-cresol, zinc sulfide carbamate, etc., and the weight percentage can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, etc.

[0055] The extreme pressure anti-wear agent accounts for 1.5-3% of the raw material composition by weight; for example, the extreme pressure anti-wear agent can be zinc dialkyl dithiophosphate, triglyceride sulfide, phosphate ester, etc., and the weight percentage can be 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, etc.

[0056] The dispersant accounts for 0.5-2% of the raw material components by weight; for example, the dispersant can be a succinimide dispersant, such as polyisobutylene succinimide, polyisobutylene bis(succinimide) and boronized polyisobutylene succinimide, etc., and the weight percentage can be 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, etc.

[0057] The rust inhibitor accounts for 0.1-0.5% of the raw material components by weight; for example, the rust inhibitor can be barium sulfonate, potassium sulfonate, sodium sulfonate, zinc epoxy, potassium ricinoleate, dodecenyl succinic acid, etc., and the weight percentage can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, etc.

[0058] The defoamer accounts for 0.001-0.01% of the raw material components by weight; for example, the defoamer can be dimethyl silicone oil, and the weight percentage can be 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, etc.

[0059] The pour point depressant accounts for 0.5-1.5% of the raw material composition by weight. For example, the pour point depressant can be alkyl naphthalene, polymethyl methacrylate, polyalphaolefin, etc., and the weight percentage can be 0.5%, 0.8%, 1%, 1.2%, 1.5%, etc.

[0060] Furthermore, the dispersant is selected from polyether fatty acid esters;

[0061] The structural formula of the above polyether fatty acid ester is shown in formula (2) below.

[0062] R 4 -COO(CH2CH2O) y (CH2CH3CHO) z R 5 (2)

[0063] Among them, R 4 It is a C6-C24 alkyl group, R 5 Selected from H or methyl, y≥0, z≥0, 3≤y+z≤12.

[0064] Antioxidants, extreme pressure anti-wear agents, and rust inhibitors are all polar compounds, or even highly polar compounds or organic salts. They have poor compatibility with low-polarity base oils (such as mineral oils), or may have density differences, leading to incompatibility or separation. Polyether fatty acid esters have good amphiphilicity and can effectively disperse the polar raw material components in composite lubricating oils, improving the uniformity and stability of the mixed raw material components.

[0065] Furthermore, in the polyether fatty acid ester shown in formula (2) above, R 4 It is a C8-C18 alkyl group, y = 0. That is, the polyether fatty acid ester shown in the above formula (2) does not contain EO, which can improve the heat resistance, hydrolysis resistance and other properties.

[0066] On the other hand, the present invention also proposes a method for preparing the composite lubricating oil described in any of the above embodiments, wherein the base oil is heated to 80-120°C, nano-alumina and nano-silica are added, ultrasonically dispersed evenly, organic functional additives are added, stirred and dispersed evenly, and the temperature is lowered to no more than 40°C to obtain the composite lubricating oil.

[0067] Base oils generally have a high viscosity. Heating them to 80-120℃ during lubricant preparation can reduce their viscosity, which is beneficial for rapid and uniform blending of the base oil with other raw material components.

[0068] The technical solutions of the present invention will be further described and illustrated below with reference to various embodiments and comparative examples. Unless otherwise specified, the parts mentioned in the following embodiments and comparative examples are parts by weight.

[0069] Polyether silane coupling agent 1: (CH3O)3Si(CH2)3O(EO) 2.6 (PO) 10.4 CH3;

[0070] Polyether silane coupling agent 2: (CH3O)3Si(CH2)3O(EO) 3.1 (PO) 15.8 CH3;

[0071] Polyether silane coupling agent 3: (CH3O)3Si(CH2)3O(EO) 2.1 (TO) 13.7 H;

[0072] Preparation Examples 1-3: Preparation of Surface-Treated Nano-Alumina

[0073] Preparation Example 1

[0074] Three parts of nano-alumina with an average particle size of 60 nm were dispersed in 100 parts of a mixed solvent composed of anhydrous ethanol and water in a volume ratio of 9:1. The pH was adjusted to 4-4.5 with hydrochloric acid, and 0.6 parts of polyether silane coupling agent 1 were added. The mixture was stirred at room temperature for 1 h, heated to a micro-reflux state, and reacted for another 3 h. The mixture was then cooled, the solid particles were collected, and washed three times with anhydrous ethanol. The mixture was dried overnight at 60 °C to obtain polyether-surface-treated nano-alumina, denoted as A-1.

[0075] Preparation Example 2

[0076] The difference between this preparation example and Preparation Example 1 is that in Preparation Example 1, the average particle size of the nano-alumina was adjusted to 50 nm, and polyether silane coupling agent 1 was adjusted to an equal weight of polyether silane coupling agent 2. The remaining steps remained unchanged, and polyether-surface-treated nano-alumina was obtained, denoted as A-2.

[0077] Preparation Example 3

[0078] The difference between this preparation example and Preparation Example 1 is that in Preparation Example 1, polyether silane coupling agent 1 was replaced with an equal weight of polyether silane coupling agent 3. The remaining steps remained unchanged, resulting in polyether-surface-treated nano-alumina, denoted as A-3.

[0079] Preparation Examples 4-7: Preparation of Surface-Treated Nano-Silica

[0080] Preparation Example 4

[0081] Five parts of nano-alumina with an average particle size of 28 nm were dispersed in 100 parts of a mixed solvent composed of anhydrous ethanol and water in a volume ratio of 9:1. The pH was adjusted to 4-4.5 with hydrochloric acid, and 1.5 parts of polyether silane coupling agent 1 were added. The mixture was stirred at room temperature for 1 h, heated to a micro-reflux state, and reacted for another 3 h. The mixture was then cooled, the solid particles were collected, and washed three times with anhydrous ethanol. The mixture was dried overnight at 60 °C to obtain polyether-surface-treated nano-silica, denoted as S-1.

[0082] Preparation Example 5

[0083] The difference between this preparation example and Preparation Example 4 is that in Preparation Example 4, the average particle size of the nano-silica was adjusted to 10 nm, and the polyether silane coupling agent 1 was adjusted to an equal weight of polyether silane coupling agent 2. The remaining steps remained unchanged, and polyether-surface-treated nano-silica was obtained, denoted as S-2.

[0084] Preparation Example 6

[0085] The difference between this preparation example and Preparation Example 4 is that in Preparation Example 4, the average particle size of the nano-silica was adjusted to 20 nm, and the polyether silane coupling agent 1 was adjusted to an equal weight of polyether silane coupling agent 3. The remaining steps remained unchanged, and polyether-surface-treated nano-silica was obtained, denoted as S-3.

[0086] Preparation Example 7

[0087] The difference between this preparation example and Preparation Example 4 is that in Preparation Example 4, the average particle size of the nano-silica was adjusted to 35 nm. The remaining steps remained unchanged, resulting in polyether-treated nano-silica, denoted as S-4.

[0088] Example 1

[0089] The compound lubricating oil, by 100% by weight, comprises: 1% nano-alumina A-1 from Preparation Example 1, 0.8% nano-silica S-1 from Preparation Example 4, 0.6% antioxidant 2,6-di-tert-butyl phenol mixture, 2% extreme pressure anti-wear agent zinc dialkyl dithiophosphate, 1.2% dispersant polyisobutylene succinimide, 0.2% rust inhibitor zinc epoxy, 0.005% defoamer dimethyl silicone oil, 0.7% pour point depressant polymethyl methacrylate, and the balance being base oil (composed of 150SN mineral oil and trimethylolpropane oleate in a weight ratio of 2:1).

[0090] Heat the base oil to 90°C, add nano alumina and nano silica in sequence, ultrasonically disperse for 20 minutes, add each organic functional additive at a stirring speed of 800 rpm, increase the stirring speed to 1500 rpm, continue stirring and dispersing for 30 minutes, and cool down to 30°C to obtain the composite lubricating oil.

[0091] Example 2

[0092] The difference between this embodiment and Example 1 is that in Example 1, the nano-silica S-1 of Preparation Example 4 was replaced with an equal weight of nano-silica S-2 of Preparation Example 5. The remaining steps remained unchanged.

[0093] Example 3

[0094] The difference between this embodiment and Example 1 is that in Example 1, the nano-silica S-1 of Preparation Example 4 was replaced with an equal weight of nano-silica S-3 of Preparation Example 6. The remaining steps remained unchanged.

[0095] Example 4

[0096] The difference between this embodiment and Example 1 is that in Example 1, the nano-silica S-1 of Preparation Example 4 was replaced with an equal weight of nano-silica S-4 of Preparation Example 7. The remaining steps remained unchanged.

[0097] Example 5

[0098] The difference between this embodiment and Example 1 is that in Example 1, the nano-alumina A-1 of Preparation Example 1 is replaced with an equal weight of nano-alumina A-2 of Preparation Example 2. The remaining steps remain unchanged.

[0099] Example 6

[0100] The difference between this embodiment and Example 5 is that in Example 5, the nano-silica S-1 of Preparation Example 4 is replaced with an equal weight of nano-silica S-2 of Preparation Example 5. The remaining steps remain unchanged.

[0101] Example 7

[0102] The difference between this embodiment and Example 5 is that in Example 5, the nano-silica S-1 of Preparation Example 4 is replaced with an equal weight of nano-silica S-3 of Preparation Example 6. The remaining steps remain unchanged.

[0103] Example 8

[0104] The difference between this embodiment and Example 5 is that in Example 5, the nano-silica S-1 of Preparation Example 4 is replaced with an equal weight of nano-silica S-4 of Preparation Example 7. The remaining steps remain unchanged.

[0105] Comparative Example 1

[0106] The difference between this comparative example and Example 1 is that in Example 1, the nano-alumina A-1 used in Preparation Example 1 was replaced with nano-alumina (average particle size 60 nm) treated with KH-560 silane coupling agent. The remaining steps remained unchanged.

[0107] Nano-alumina treated with KH-560 silane coupling agent was surface-treated with KH-560 according to the method of Preparation Example 1.

[0108] Comparative Example 2

[0109] The difference between this comparative example and Example 1 is that in Example 1, the nano-silica S-1 used in Preparation Example 4 was replaced with nano-silica (average particle size 28 nm) treated with dodecyltrimethoxysilane. The remaining steps remained unchanged.

[0110] Dodecyltrimethoxysilane-treated nano-silica was prepared by surface treatment of nano-silica with dodecyltrimethoxysilane according to the method of Preparation Example 4.

[0111] Example 9

[0112] The compound lubricating oil, by 100% weight, comprises: 0.8% nano-alumina A-3 of Preparation Example 3, 0.5% nano-silica S-1 of Preparation Example 4, 0.8% antioxidant 2,6-di-tert-butyl-p-cresol, 2.2% extreme pressure anti-wear agent zinc dialkyl dithiophosphate, 1% dispersant polyisobutylene succinimide, 0.2% rust inhibitor zinc epoxy, 0.008% defoamer dimethyl silicone oil, 1% pour point depressant polymethyl methacrylate, and the balance being base oil (150SN mineral oil).

[0113] Example 10

[0114] The difference between this embodiment and Embodiment 9 is that in Embodiment 9, the dispersant polyisobutylene succinimide is replaced with an equal weight of polyether fatty acid ester n-C8H. 17 (CH2CH3CHO) 4.1 CH3. The remaining steps remain unchanged.

[0115] Example 11

[0116] The difference between this embodiment and Embodiment 9 is that in Embodiment 9, the base oil was replaced by an equal weight of trimethylolpropane oleate instead of 150SN mineral oil. The remaining steps remain unchanged.

[0117] Example 12

[0118] The difference between this embodiment and Embodiment 11 is that in Embodiment 11, the dispersant polyisobutylene succinimide is replaced with an equal weight of polyether fatty acid ester nC. 12 H 25 (CH2CH3CHO) 5.8 CH3. The remaining steps remain unchanged.

[0119] Performance testing

[0120] Centrifugal stability: Take 20ml of the composite lubricating oil to be tested and centrifuge at 5000rpm for 10min. Observe whether precipitation occurs. If precipitation occurs, filter the precipitate with filter paper, wash with anhydrous ethanol, dry and weigh, and measure the sedimentation rate. No precipitation or sedimentation rate less than 0.1% is excellent and marked with "√"; sedimentation rate of 0.1-0.5% is acceptable and marked with "△"; sedimentation rate exceeding 0.5% or stratification is unacceptable and marked with "×".

[0121] Accelerate storage stability: Take 20ml of the composite lubricating oil to be tested into a transparent glass bottle, seal it, and place it in a 40℃ environment for 6 months. Observe whether any abnormalities such as stratification, sedimentation, or discoloration occur. If any abnormalities occur, it is unqualified and marked with "×"; if no abnormalities occur, it is qualified and marked with "√".

[0122] Load performance test: The sintering load P was tested according to the method of GB / T 3142-2019. D Value. P D The higher the value, the better the wear resistance.

[0123] The results are shown in Table 1 below.

[0124] Table 1

[0125] centrifuge stability accelerated storage stability P D value / N example 1 √ √ 5217 example 2 √ √ 4822 example 3 √ √ 5660 example 4 √ √ 4075 example 5 √ √ 3853 example 6 √ √ 4778 example 7 √ √ 5265 example 8 √ √ 3471 comparative example 1 × × / comparative example 2 × × / example 9 △ × 4784 example 10 √ √ 5267 example 11 √ √ 5478 example 12 √ √ 6083

[0126] Therefore, as shown in Table 1 above, compared with Comparative Examples 1 and 2, the composite lubricating oil of the present invention exhibits better centrifugal stability and heating storage stability, indicating that the compatibility of each raw material component is good, and the dispersion is uniform and stable. Comparative Examples 1-8 show that the particle sizes of nano-alumina and nano-silica are within a certain range, resulting in a higher sintering load for the composite lubricating oil. Comparative Examples 9-12 show that using polyether fatty acid esters as dispersants, compared with existing succinimide dispersants, is suitable for base oils of different polarities and also results in a higher sintering load.

[0127] As described above, the basic principles, main features, and advantages of the present invention have been shown and described. Those skilled in the art should understand that the present invention is not limited to the above embodiments, which are merely preferred embodiments and should not be construed as limiting the scope of the invention. All equivalent changes and modifications made in accordance with the scope of the patent and the description should still fall within the scope of the present invention. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A compounded lubricating oil characterized by, The raw material components comprise, by weight of 100%, 90-95% base oil, 0.5-1.5% nano-alumina, 0.2-1% nano-silica, and 2-10% organic functional additives; The nano-alumina and the nano-silica are independently surface treated with a polyether silane coupling agent; The polyether silane coupling agent has a structural formula as shown in the following formula (1), R 1 -Z-(CH2)3R 2 x Si(OR 3 ) 3-x (1) wherein R 1 is selected from C1-C12 alkyl, R 2 and R 3 is independently selected from C1-C4 alkyl, Z represents a polyether segment, x = 0-1.

2. The complex lubricating oil according to claim 1, characterized in that, The polyether chain segment consists of at least one of a polyethylene glycol chain segment, a polypropylene glycol chain segment, and a polytetrahydrofuran ether glycol chain segment; The molar content of the polyethylene glycol chain segment in the polyether chain segment is not more than 20%.

3. The complex lubricating oil according to claim 1, characterized in that, The molar content of the polytetrahydrofuran ether glycol chain segment in the polyether chain segment is not less than 50%.

4. The complex lubricating oil according to claim 1, wherein The number average molecular weight of the polyether chain segment is 100-1000.

5. The complex lubricating oil according to claim 1, wherein The average particle size of the nano-alumina is a, the average particle size of the nano-silica is b, then: a=10-100nm, b=10-50nm, b=(0.15-0.5)a.

6. The complex lubricating oil according to claim 5, characterized in that, The values of a and b satisfy: b=(0.25-0.5)a.

7. The complex lubricating oil of claim 1, wherein The organic functional additives are selected from one or a combination of two or more of an antioxidant, an extreme pressure anti-wear agent, a dispersant, a rust inhibitor, a defoaming agent, and a pour point depressant.

8. The complex lubricating oil according to claim 7, characterized in that, The weight percentage of the antioxidant in the raw material components is 0.5-1%; The weight percentage of the extreme pressure anti-wear agent in the raw material components is 1.5-3%; The weight percentage of the dispersant in the raw material components is 0.5-2%; The weight percentage of the rust inhibitor in the raw material components is 0.1-0.5%; The weight percentage of the defoaming agent in the raw material components is 0.001-0.01%; The weight percentage of the pour point depressant in the raw material components is 0.5-1.5%.

9. The complex lubricating oil according to claim 7, wherein The dispersant is selected from a polyether fatty acid ester; The polyether fatty acid ester has a structural formula as shown in the following formula (2), R 4 -COO(CH2CH2O) y (CH2CH3CHO) z R 5 (2) wherein R 4 is C6-C24alkyl, R 5 is selected from H or methyl, y > 0, z > 0, 3 < y + z < 12.

10. A process for the preparation of a complex lubricating oil as claimed in any one of claims 1 to 9, characterised in that, The base oil is heated to 80-120℃, the nano-alumina and the nano-silica are added and uniformly dispersed by ultrasonic, and then the organic functional additives are continuously added and uniformly dispersed by stirring, and the temperature is reduced to not more than 40℃, thereby obtaining the composite lubricating oil.