Four-stroke unmanned aerial vehicle engine lubricating oil composition and preparation method thereof

Abstract

The invention provides a four-stroke unmanned aerial vehicle engine lubricating oil composition. The four-stroke unmanned aerial vehicle engine lubricating oil composition comprises phosphate salt, polyisobutylene succinimide, sulfonate, alkyl diphenylamine, a hydrogenated styrene-isoprene copolymer and a main amount of lubricating oil base oil. Wherein the structure of the phosphate salt is shown in the specification. The four-stroke unmanned aerial vehicle engine lubricating oil composition provided by the invention has excellent wear resistance and oxidation resistance.

Description

Technical Field

[0001] The present invention relates to a lubricating oil composition, and particularly to a lubricating oil composition for a four-stroke UAV engine and a preparation method thereof. Background Art

[0002] Unmanned aerial vehicles (UAVs) are a new type of aircraft that can be remotely controlled to perform various tasks such as aerial photography, mapping, transportation, strike, and rescue without a pilot on board, and have a wide range of applications in various industries and fields. Medium and large UAVs are commonly powered by aviation piston engines, which are mainly divided into two categories: four-stroke and two-stroke. A four-stroke engine's working cycle includes four processes: intake, compression, combustion and power stroke, and exhaust. A two-stroke engine combines intake and exhaust, shortening the working cycle by half and enabling power improvement, but the engine has greater heat dissipation problems. Relatively speaking, the four-stroke engine is more perfect. An intuitive difference between two-stroke and four-stroke aviation piston engines is the lubricating oil usage method. In a two-stroke engine, the lubricating oil is added to the fuel in a certain proportion and enters the combustion chamber together, while the engine oil in a four-stroke engine is recycled. However, different from gasoline engine oils in passenger cars, the engine oil in a four-stroke UAV also plays a role in lubricating the transmission. To increase the protection of gears and reduce wear, an anti-wear agent needs to be added to the oil product to improve its performance.

[0003] Some molecules containing phosphorus atoms are widely used as additives in lubricating oils due to their excellent anti-wear properties. For example, sulfur-free and metal-free molecules such as phosphate esters, phosphite esters, and amine salts of phosphate esters have advantages such as good anti-wear performance, low metal corrosion, low ash content, and low odor as anti-wear components. Although the amine salts of phosphate esters anti-wear agents disclosed in the prior art can improve the anti-wear effect of lubricating oils, their dosage is generally high, making it difficult for the product to meet the increasingly strict phosphorus element content limit. At the same time, high-concentration acidic phosphate esters may also affect the performance of other additives.

[0004] Therefore, under the existing technical conditions, there is still a need for a lubricating oil composition for a four-stroke UAV engine, which not only needs to meet the increasingly stringent requirements of the product for anti-wear performance, but also needs to have more excellent antioxidant performance to extend the service life of the product. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a lubricating oil composition for a four-stroke UAV engine and a preparation method thereof.

[0006] The lubricating oil composition for a four-stroke UAV engine of the present invention comprises:

[0007] (A) Phosphate salt, accounting for 0.05% to 10% (preferably 0.2% to 5%) of the total mass of the composition;

[0008] (B) Polyisobutylene succinimide, accounting for 1% to 30% (preferably 3% to 20%) of the total mass of the composition;

[0009] (C) Sulfonate, accounting for 0.2% to 10% (preferably 2% to 8%) of the total mass of the composition;

[0010] (D) Alkyldiphenylamine, accounting for 0.05% to 5% (preferably 0.1% to 4%) of the total mass of the composition;

[0011] (E) Hydrogenated styrene-isoprene copolymer, accounting for 0.1% to 3% (preferably 0.2% to 1.5%) of the total mass of the composition;

[0012] (F) A major amount of lubricating oil base oil;

[0013] Wherein the phosphate salt includes a structural unit shown in formula (1), and at least one of the structural units shown in formula (2), formula (3) and formula (4),

[0014] Wherein, R1 and R2 are each independently selected from hydrogen, hydrocarbon group, substituted hydrocarbon group or heteroalkyl group;

[0015] Wherein, X1 is selected from nitrogen or methylene, R and R’ are each independently selected from hydrogen or a C1-C4 hydrocarbon group; R3, R4 and R5 are each independently selected from a C1-C5 hydrocarbon group, and r1 and r2 are each independently 0 or 1;

[0016] Wherein, R6, R7 and R8 are each independently selected from a C1-C5 hydrocarbon group, and r3 and r4 are each independently 0 or 1;

[0017] Wherein, R” is selected from hydrogen or a C1-C4 hydrocarbon group, R9, R 10 and R 11 are each independently selected from a C1-C5 hydrocarbon group, and r5 and r6 are each independently 0 or 1.

[0018] According to the present invention, the preparation method of the phosphate salt includes:

[0019] Contacting an acidic phosphate having a structure shown in formula (5) with a nitrogen-containing organic compound having a bicyclic structure to carry out a phosphate salt formation reaction;

[0020] Wherein, R1 and R2 are each independently selected from hydrogen, hydrocarbon group, substituted hydrocarbon group or heteroalkyl group;

[0021] Wherein, the nitrogen-containing organic compound has at least one of the structures shown in formula (6), formula (7) and formula (8),

[0022] Wherein, X1 is selected from nitrogen or methylene, R and R' are each independently selected from hydrogen or a C1-C4 hydrocarbyl group; R3, R4 and R5 are each independently selected from a C1-C5 hydrocarbyl group, and r1 and r2 are each independently 0 or 1;

[0023] Wherein, R6, R7 and R8 are each independently selected from a C1-C5 hydrocarbyl group, and r3 and r4 are each independently 0 or 1;

[0024] Wherein, R” is selected from hydrogen or a C1-C4 hydrocarbyl group, R9, R 10 and R 11 are each independently selected from a C1-C5 hydrocarbyl group, and r5 and r6 are each independently 0 or 1.

[0025] According to the present invention, the phosphate salt does not contain metal elements, is not prone to generate ash, shows remarkable anti-wear property at a relatively small dosage, and can effectively improve the anti-wear property and load-carrying capacity of the lubricating oil. In addition, when the phosphate salt is used as an anti-wear additive for lubricating oil, it has a relatively low metal corrosion while showing excellent anti-wear property.

[0026] According to the present invention, the component (B) is polyisobutylene succinimide, preferably polyisobutylene succinimide with a number-average molecular weight of 1000-4000 for the polyisobutylene group, such as T151, T161 produced by Sinopec Yangzi Petrochemical Co., Ltd., T151, T161 produced by Wuxi Southern Petroleum Additive Co., Ltd., T151, T161 produced by Jinzhou Kangtai Lubricant Additive Co., Ltd., T151, T161 produced by Xinxiang Ruifeng New Materials Co., Ltd., etc.

[0027] According to the present invention, the component (C) is sulfonate, preferably sulfonate with a base number of 20-450 mgKOH / g, and one or more of low-base-number sulfonate, medium-base-number sulfonate and high-base-number sulfonate can be selected, preferably high-base-number sulfonate. The sulfonate can be T101, T104, T106B produced by Wuxi Southern Petroleum Additive Co., Ltd., BD C020, T104, T106 produced by Jinzhou Kangtai Lubricant Additive Co., Ltd., RF1104, RF1105, RF1106 of Xinxiang Ruifeng New Materials Co., Ltd., etc.

[0028] According to the present invention, the component (D) is alkyl diphenylamine, preferably wherein the alkyl group is C 4～10The alkyl diphenylamine of straight-chain or branched-chain alkyl can be T534 produced by Xinxiang Ruifeng New Materials Co., Ltd., IRGANOX L-06 and IRGANOX L-57 produced by BASF Germany, VANLUBE SS, VANLUBE 961 and VANLUBE 81 produced by Vanderbilt USA, p-diisooctyl diphenylamine RC7001 produced by Rhein Chemie Germany, etc.

[0029] According to the present invention, the component (E) is a hydrogenated styrene-isoprene copolymer, preferably a hydrogenated styrene-isoprene copolymer with a number-average molecular weight of 600,000 to 6 million, and SEPSYH-4030 produced by Sinopec Baling Petrochemical Co., Ltd., SV260 produced by Infineum, etc. can be selected.

[0030] According to the present invention, the component (F) is a lubricating oil base oil, preferably a mineral base oil and / or a synthetic base oil. The mineral base oil includes liquid paraffin oil, hydrorefined mineral lubricating oil, etc., and is usually divided into Group I, Group II, and Group III base oils; the synthetic lubricating oil includes polymerized hydrocarbon oil, alkylbenzene and its derivatives, ester oil, Fischer-Tropsch synthetic hydrocarbon oil, etc. The lubricating oil base oil can be a mixture of a mineral base oil and a synthetic base oil. For example, a mixture of a Group III hydrotreated base oil, a polyol ester base oil, and a polyalphaolefin base oil can be selected, and the mass ratio among the three can be 1:0.5-2:3-10.

[0031] The present invention also provides a preparation method of a four-stroke UAV engine lubricating oil composition, including the step of mixing the additives and the lubricating oil base oil in the aforementioned lubricating oil composition. The temperature of the mixing is preferably 40-90°C, and the mixing time is preferably 1-6 h.

[0032] The four-stroke UAV engine lubricating oil composition of the present invention has excellent anti-wear performance and antioxidant performance. Detailed Embodiments

[0033] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and a single point value, and between single point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0034] The present invention will be further described in detail below in conjunction with embodiments. However, the present invention is not limited thereto. Unless otherwise specified, all ratios and parts are calculated by mass.

[0035] In the first aspect of the present invention, a phosphate salt is provided. The phosphate salt includes a structural unit represented by formula (1), and at least one of the structural units represented by formula (2), formula (3), and formula (4).

[0036] Wherein, R1 and R2 are each independently selected from hydrogen, hydrocarbon group, substituted hydrocarbon group or heteroalkyl group;

[0037] Wherein, X1 is selected from nitrogen or methine, R and R’ are each independently selected from hydrogen or C1-C4 hydrocarbon group; R3, R4 and R5 are each independently selected from C1-C5 hydrocarbon group, and r1 and r2 are each independently 0 or 1;

[0038] Wherein, R6, R7 and R8 are each independently selected from C1-C5 hydrocarbon group, and r3 and r4 are each independently 0 or 1;

[0039] Wherein, R” is selected from hydrogen or C1-C4 hydrocarbon group, R9, R 10 and R 11 are each independently selected from C1-C5 hydrocarbon group, and r5 and r6 are each independently 0 or 1.

[0040] In the prior art, phosphate amine salts usually require a relatively high dosage when used as lubricating oil anti-wear additives. Through continuous research, the inventors of the present invention found that phosphate organic base salts with a nitrogen-containing bicyclic structure can show significant anti-wear properties at a relatively low dosage level, and can effectively improve the anti-wear performance and load-carrying capacity of lubricating oils. This phosphate salt does not contain metal elements, is not prone to generating ash, and at the same time has low metal corrosion while showing excellent anti-wear performance, and has outstanding progress compared with the phosphate amine salt compounds in the prior art.

[0041] In the present invention, R1 and R2 are each independently selected from hydrogen, hydrocarbon group, substituted hydrocarbon group or heteroalkyl group. Preferably, R1 and R2 are not both hydrogen at the same time.

[0042] Wherein, the “hydrocarbon group” has the meaning conventionally known in the art, including but not limited to straight-chain or branched-chain alkyl group, straight-chain or branched-chain alkenyl group, straight-chain or branched-chain alkynyl group, cycloalkyl group, cycloalkenyl group, cycloalkynyl group, aryl group or a combined group thereof. Preferably, the hydrocarbon group is a C1-C20 hydrocarbon group, including but not limited to straight-chain or branched-chain alkyl groups of C1-C20, straight-chain or branched-chain alkenyl groups of C2-C20, straight-chain or branched-chain alkynyl groups of C2-C20, cycloalkyl groups of C3-C20, cycloalkenyl groups of C3-C20, cycloalkynyl groups of C3-C20, aryl groups of C6-C20 or a combined group thereof.

[0043] In the present invention, the "substituted hydrocarbon group" refers to a group obtained by directly substituting one or more hydrogens in a hydrocarbon group molecule with substituents, and the substituents include but are not limited to at least one of a fluorine atom, a chlorine atom, a bromine atom, a hydroxyl group, a mercapto group, an alkoxy group, and an alkylthio group.

[0044] In the present invention, the "heteroalkyl group" refers to a group obtained by directly substituting one or more carbon atoms inside the alkyl group structure (excluding the ends of the main chain or any side chain in the alkyl group structure). It can be understood that from the perspective of structural stability, when there are multiple heteroatoms, these heteroatoms are not directly bonded to each other. In the present invention, although the number of carbon atoms in the alkyl group decreases due to the substitution of carbon atoms by heteroatoms, for the sake of simplicity in expression, the number of carbon atoms in the alkyl group before the substitution is still used to refer to the number of carbon atoms in the heteroalkyl group.

[0045] For example, a C4 straight-chain alkyl group such as (the group indicated by the arrow is at the end of the main chain) being directly substituted by a substitution group -O- will obtain -CH2-O-CH2-CH3 or -CH2-CH2-O-CH3, which is called a C4 straight-chain heteroalkyl group. Or, a C4 branched-chain alkyl group such as (the group indicated by the arrow is not inside the molecular structure but at the ends of the main chain and the side chain) where the methylene group is directly substituted by a substitution group -N< will obtain which is called a C4 branched-chain heteroalkyl group. According to the present invention, the heteroalkyl group includes but is not limited to a C3-C20 straight-chain or branched-chain heteroalkyl group, preferably a C3-C10 straight-chain or branched-chain heteroalkyl group.

[0046] Preferably, the heteroatom in the heteroalkyl group is at least one of O, N, and S, preferably O and / or S, and further preferably S.

[0047] According to the present invention, preferably, R1 and R2 each independently selected from a C4-C18 hydrocarbon group, a C4-C18 hydroxy-substituted hydrocarbon group, or a C3-C20 heteroalkyl group, including but not limited to n-butyl, isobutyl, tert-butyl, n-hexyl, 2-ethylhexyl, n-octyl, 1-methylheptyl, 3,5,5-trimethylhexyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl, 9-octadecenyl, 9,12-octadecadienyl, 12-hydroxy-9-octadecenyl, cyclohexyl, phenyl, methylphenyl, or dimethylphenyl.

[0048] According to the present invention, in formula (2), r1 and r2 are each independently 0 or 1. It can be understood that when r1 is 0, it means that the R4 group does not exist, and at this time, the N atom and the C atom on both sides of R4 in formula (2) are directly connected. Similarly, when r2 is 0, it means that the R5 group does not exist, and at this time, the N and X1 on both sides of R5 in formula (2) are directly connected. The meanings of r3, r4, r5 and r6 in formula (3) and formula (4) are the same as those of r1 and r2, and will not be elaborated here.

[0049] In the present invention, as long as the phosphate salt has a phosphate group and a nitrogen-containing bicyclic structure, the anti-wear performance of the lubricating oil can be improved, and the anti-wear performance and metal corrosion resistance can be further optimized by controlling the size (number of carbon atoms) of the bicyclic ring. For example, by adjusting the number of main chain carbon atoms of the R3, R4 and R5 groups in formula (2), the size of the bicyclic structure in formula (2) can be controlled. Similarly, in the structures shown in formula (3) and formula (4), by adjusting the number of main chain carbon atoms of R6, R7 and R8 and R9, R 10 and R 11 groups respectively, the size of the bicyclic structure in formula (2) and formula (3) can be controlled.

[0050] According to the present invention, preferably, in formula (2) - formula (4), R3, R6, R9 are each independently -(CH2) a -, where a is selected from 2 - 5.

[0051] According to the present invention, preferably, R4, R7, R 10 are each independently -(CH2) b -, where b is 1 - 2.

[0052] According to the present invention, preferably, R5, R8, R 11 are each independently -(CH2) c -, where c is 1 - 3.

[0053] Through the above-mentioned preferred number of rings and three-dimensional structure of the nitrogen-containing organic matter, the basicity of such compounds and the dispersibility in the base oil can be controlled, and nitrogen-containing organic matter with sufficiently stable chemical properties can also be selected according to the use environment.

[0054] According to the present invention, the phosphate salt can exist, be manufactured or used in the form of a single (pure) compound, or can exist, be manufactured or used in the form of a mixture of two or more of them (in any proportion), which does not affect the realization of the effects of the present invention.

[0055] According to the present invention, there is no particular limitation on the preparation method of the phosphate salt, and it can be prepared by any known method in the art.

[0056] The second aspect of the present invention provides a method for preparing the phosphate salt, which method comprises:

[0057] Contacting an acidic phosphate having the structure shown in formula (5) with a nitrogen-containing organic compound having a bicyclic structure to carry out a reaction for forming the phosphate salt;

[0058] wherein, R1 and R2 are each independently selected from hydrogen, a hydrocarbon group, a substituted hydrocarbon group or a heteroalkyl group;

[0059] wherein, the nitrogen-containing organic compound has at least one of the structures shown in formula (6), formula (7) and formula (8),

[0060] wherein, X1 is selected from nitrogen or methine, R and R' are each independently selected from hydrogen or a C1-C4 hydrocarbon group; R3, R4 and R5 are each independently selected from a C1-C5 hydrocarbon group, and r1 and r2 are each independently 0 or 1;

[0061] wherein, R6, R7 and R8 are each independently selected from a C1-C5 hydrocarbon group, and r3 and r4 are each independently 0 or 1;

[0062] wherein, R” is selected from hydrogen or a C1-C4 hydrocarbon group, R9, R 10 and R 11 are each independently selected from a C1-C5 hydrocarbon group, and r5 and r6 are each independently 0 or 1.

[0063] In the present invention, the acidic phosphate can directly use commercially available products or can be manufactured by methods conventionally known in the art, and the present invention has no particular limitation thereto. Additionally, the acidic phosphate can use only one kind or can use a combination of two or more kinds, as long as the structure shown in formula (5) is satisfied.

[0064] According to the present invention, preferably, in formula (5), R1 and R2 are not simultaneously hydrogen.

[0065] Preferably, R1 and R2 are each independently selected from a C4-C18 hydrocarbon group, a C4-C18 hydroxy-substituted hydrocarbon group or a C3-C20 heteroalkyl group.

[0066] Preferably, the heteroatom in the heteroalkyl group is at least one of O, N and S, preferably O and / or S, and more preferably S.

[0067] Preferably, R1 and R2 are each independently selected from n-butyl, isobutyl, tert-butyl, n-hexyl, 2-ethylhexyl, n-octyl, 1-methylheptyl, 3,5,5-trimethylhexyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl, 9-octadecenyl, 9,12-octadecadienyl, 12-hydroxy-9-octadecenyl, cyclohexyl, phenyl, methylphenyl or dimethylphenyl.

[0068] According to the present invention, the acidic phosphate ester includes but is not limited to monobutyl phosphate (CAS: 1623-15-0), dibutyl phosphate (CAS: 107-66-4), monoisobutyl phosphate (CAS: 2466-73-1), diisobutyl phosphate (CAS: 6303-30-6), monotert-butyl phosphate (CAS: 2382-75-4), ditert-butyl phosphate (CAS: 33494-81-4), monon-hexyl phosphate (CAS: 3900-04-7), di-n-hexyl phosphate (CAS: 3900-13-8), monophenyl phosphate (CAS: 701-64-4), diphenyl phosphate (CAS: 838-85-7), benzyl phosphate (CAS: 1623-07-0), dibenzyl phosphate (CAS: 1623-08-1), mono(methylphenyl) phosphate, di(methylphenyl) phosphate, monon-octyl phosphate (CAS: 3991-73-9), di-n-octyl phosphate (CAS: 3115-39-7), mono(2-ethylhexyl) phosphate (CAS: 1070-03-7), di(2-ethylhexyl) phosphate (CAS: 298-07-7), mono(1-methylheptyl) phosphate (CAS: 10353-73-8), di(1-methylheptyl) phosphate (CAS: 77076-28-9), mono(3,5,5-trimethylhexyl) phosphate (CAS: 85006-34-4), di(3,5,5-trimethylhexyl) phosphate (CAS: 7153-98-2), monon-decyl phosphate (CAS: 3921-30-0), di-n-decyl phosphate (CAS: 7795-87-1), monolauryl phosphate, dilauryl phosphate, myristyl phosphate, dimyristyl phosphate, mono(hexadecyl) phosphate, di(hexadecyl) phosphate, monostearyl phosphate, distearyl phosphate, mono(9-octadecenyl) phosphate, di(9-octadecenyl) phosphate, mono(9,12-octadecadienyl) phosphate, di(9,12-octadecadienyl) phosphate, mono(12-hydroxy-9-octadecenyl) phosphate and di(12-hydroxy-9-octadecenyl) phosphate, or isomers of the above compounds.

[0069] The present invention does not particularly limit the source of the nitrogen-containing organic compound having a bicyclic structure. A commercially available product can be directly used, or it can be manufactured by a method conventionally known in the art. The nitrogen-containing organic compound can be used alone, or two or more of them can be used in combination, as long as at least one of the structures shown in Formula (6), Formula (7) and Formula (8) is satisfied.

[0070] According to the present invention, preferably, in Formula (6)-Formula (8), R3, R6, and R9 are each independently -(CH2) a -, where a is selected from 2-5.

[0071] Preferably, R4, R7, R 10 are each independently -(CH2) b -, where b is 1-2.

[0072] Preferably, R5, R8, R 11 are each independently -(CH2) c -, where c is 1-3.

[0073] According to the present invention, the nitrogen-containing organic compound includes but is not limited to 1,4-diazabicyclo[2.2.2]octane (CAS: 280-57-9), 1-azabicyclo[2.2.2]octane (quinuclidine, CAS: 100-76-5), 1,5-diazabicyclo[4.3.0]-5-nonene (CAS: 3001-72-7), 1,8-diazabicyclo[5.4.0]undec-7-ene (abbreviation: DBU, CAS: 6674-22-2), and any proportion mixture of the above compounds.

[0074] In the present invention, preferably, the molar ratio of the amount of the acidic phosphate ester to the nitrogen-containing organic compound is 1:0.1-10, preferably 1:0.4-5, and more preferably 1:0.5-2.

[0075] The present invention has a relatively wide selection range for the reaction temperature at which the phosphate salt reacts. Preferably, the reaction temperature is 0-200°C, preferably 20-150°C, and further preferably 60-120°C; the present invention does not have special requirements for the reaction time. To ensure sufficient reaction, preferably, the reaction time is 0.1-24 h, preferably 0.5-12 h, and further preferably 1-5 h.

[0076] The present invention does not particularly limit the reaction pressure and atmosphere for the reaction of the phosphate salt, and the reaction can be carried out under normal pressure and air conditions.

[0077] According to the present invention, the reaction of the phosphate salt can be carried out in the presence of a solvent or without the presence of a solvent, and the reaction can be achieved in both cases. Preferably, the reaction of the phosphate salt is carried out in the presence of a solvent. For example, an acidic phosphate and a nitrogen-containing organic compound are added to a reactor containing a solvent for contact, or the acidic phosphate and the nitrogen-containing organic compound are separately dissolved in a solvent, and then the two are added to the reactor for the reaction of the phosphate salt to occur. The present invention has no particular requirements for the reactor, as long as the reaction conditions can be controlled within the above range, and conventional reaction devices in the art can be applied to the present invention.

[0078] The present invention has no particular requirements for the specific operating conditions for adding the above reactants to the reactor, and conventional operating methods in the art can be adopted. Preferably, the reactants are slowly added in batches or dropwise to the reactor, and the temperature is controlled within the above reaction temperature range.

[0079] The present invention also has no special limitation on the addition order of each reaction raw material, and they can be added in any order.

[0080] Preferably, the solvent is selected from at least one of C6-C10 alkanes, C6-C20 aromatic hydrocarbons, C5-C10 aliphatic ethers, C2-C20 halogenated hydrocarbons, and C3-C10 amides. The C6-C10 alkanes include but are not limited to at least one of n-hexane, cyclohexane, and petroleum ether; the C6-C20 aromatic hydrocarbons include but are not limited to at least one of benzene, toluene, xylene, and cumene; the C2-C20 halogenated hydrocarbons include but are not limited to at least one of dichloromethane, carbon tetrachloride, chlorobenzene, and 1,2-dichlorobenzene; the C5-C10 aliphatic ethers include but are not limited to at least one of methyl tert-butyl ether, 1,2-dimethoxyethane, ethylene glycol diethyl ether, and 1,4-dioxane; the C3-C10 amides include but are not limited to at least one of dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

[0081] According to the present invention, preferably, the mass ratio of the total mass of the acidic phosphate and the nitrogen-containing organic compound to the mass of the solvent is 1:0.5-10, preferably 1:0.5-5, and more preferably 1:0.8-3.

[0082] According to the present invention, only one type of solvent can be used, or a combination of two or more types can be adopted. Preferably, the preparation method further includes recovering the reaction solvent and recycling it to the same reaction. For example, the solvent can be recovered by vacuum distillation.

[0083] According to the present invention, in the preparation method of the phosphate salt, the obtained reaction product can be a single phosphate salt or a mixture containing multiple phosphate salts. These reaction products are all expected in the present invention. The phosphate salts all have the structural unit shown in formula (1) and at least one of the structural units shown in formula (2), formula (3), and formula (4). The difference in their specific existence forms does not affect the realization of the effects of the present invention. Therefore, in the context of this specification, these reaction products are collectively referred to as the phosphate salts of the present invention without distinction.

[0084] Therefore, in the present invention, the product obtained by reacting the phosphate salt can be purified or not. In order to further improve the performance of the phosphate salt, preferably, the preparation method further includes: purifying the product obtained by reacting the phosphate salt. A phosphate salt with a specific structure is separated from the product obtained by reacting the phosphate salt through the purification.

[0085] The purification can adopt any conventional purification or separation method in the art, and the present invention has no special limitation thereon. For example, column chromatography or preparative chromatography and other methods can be used to purify the reaction product.

[0086] The present invention will be described in detail below through examples.

[0087] In the following examples and comparative examples, unless otherwise specified, the raw materials used are all commercially available.

[0088] Example 1

[0089] In a 250 mL three-necked flask equipped with a magnetic stirrer, a thermometer, a condenser, and a dropping funnel, 5.59 g (49.84 mmol) of 1,4-diazabicyclo[2.2.2]octane and 44.15 g of 1,2-dimethoxyethane were added and rapidly stirred and dissolved at room temperature; 25.02 g (100.00 mmol) of diphenyl phosphate was dissolved in 49.09 g of 1,2-dimethoxyethane and slowly dropped into the three-necked flask; the temperature was raised to 85 °C, and the temperature was controlled to reflux at 80 - 85 °C for 4.5 hours. After the reaction was completed, the solvent was distilled off under reduced pressure to obtain 30.48 g of a white waxy product. The product was designated as S1. The structure of the product was characterized by gas chromatography-mass spectrometry, and the molecular weight of the main product was measured to be 350.12. According to the analysis, the structure of the main product in S1 is shown in the following formula:

[0090]

[0091] Example 2

[0092] In a 250 mL three-necked flask equipped with a magnetic stirrer, a thermometer, a condenser, and a dropping funnel, 5.60 g (49.92 mmol) of 1,4-diazabicyclo[2.2.2]octane and 46.02 g of 1,2-dimethoxyethane were added and rapidly stirred and dissolved at room temperature. 32.21 g (99.90 mmol) of bis(2-ethylhexyl) phosphate was slowly dropped into the three-necked flask, and the temperature was raised to 85 °C. The temperature was controlled between 80 - 85 °C and refluxed for 4 hours. After the reaction was completed, the solvent was removed by distillation under reduced pressure, and 37.32 g of a white waxy product was obtained. The product was designated as S2. The structure of the product was characterized by gas chromatography-mass spectrometry. The molecular weight of the main product was measured to be 434.38. According to the analysis, the structure of the main product in S2 is shown in the following formula:

[0093]

[0094] The main additives and base oil sources used in the following lubricating oil compositions are as follows:

[0095] T323, amino thioester, Jinzhou Kangtai Lubricant Additive Co., Ltd.;

[0096] T307, ammonium salt of thio-phosphoric acid diester, Jinzhou Kangtai Lubricant Additive Co., Ltd.;

[0097] T161, high molecular weight polyisobutylene succinimide dispersant, Sinopec Yangzi Petrochemical Co., Ltd.;

[0098] T106B, overbased calcium sulfonate detergent, Wuxi Nanfang Petroleum Additive Co., Ltd.;

[0099] T534, octyl butyl diphenylamine antioxidant, Xinxiang Ruifeng New Materials Co., Ltd.;

[0100] SEPS YH-4030, hydrogenated styrene-isoprene copolymer viscosity index improver, Sinopec Baling Petrochemical Co., Ltd.;

[0101] RJ-1650, neopentyl polyol ester base oil, Shandong Ruijie New Materials Co., Ltd.;

[0102] III-4 hydrotreated base oil, PAO4 synthetic base oil, Sinopec Maoming Petrochemical Company.

[0103] Examples 3 - 6 and Comparative Examples 1 - 5 of the lubricating oil composition for four-stroke UAV engines

[0104] Amino thioester (grade T323) and ammonium salt of thio-phosphoric acid diester (grade T307) produced by Jinzhou Kangtai Lubricant Additive Co., Ltd. were selected as the contrast agents, and Examples 3-6 and Comparative Examples 1-4 of the lubricating oil composition for four-stroke UAV engines were prepared according to the formulation shown in Table 1. Comparative Example 5 was a commercially available lubricating oil for four-stroke UAV engines.

[0105] Table 1 Formulation of the lubricating oil composition for four-stroke UAV engines

[0106]

[0107]

[0108] Using the lubricating oil compositions of the above examples and comparative examples as experimental samples, the anti-wear performance and antioxidant performance were evaluated respectively.

[0109] The performance evaluation was carried out according to the following method.

[0110] (1) Anti-wear performance

[0111] The high-frequency reciprocating friction test (HFRR) was carried out on the test samples. The test conditions were: load 1000 g, frequency 20 Hz, temperature 100 °C, reciprocating stroke 1 mm, and test time 60 min. The wear scar diameter (unit: μm) was recorded. The smaller the wear scar diameter, the better the anti-wear performance of the test sample.

[0112] (2) Thermal oxidation stability

[0113] The thermal oxidation stability of the test samples was evaluated by the pressure differential scanning calorimetry test (PDSC), which was expressed by the oxidation induction period (unit: min) of the test samples. The conditions of the PDSC test were: temperature 200 °C, oxygen pressure 3.5 MPa, and oxygen flow rate 100 mL / min. The longer the oxidation induction period, the better the thermal oxidation stability of the test sample.

[0114] The evaluation results are shown in Table 2.

[0115] Table 2 Performance evaluation results

[0116]

[0117]

[0118] As can be seen from Table 2, the lubricating oil composition for four-stroke UAV engines of the present invention has excellent anti-wear performance and antioxidant performance.

Claims

1. Four-stroke UAV engine lubricating oil composition, comprising: (A) Phosphate salt, accounting for 0.05% - 10% of the total mass of the composition; (B) Polyisobutylene succinimide, accounting for 1% - 30% of the total mass of the composition; (C) Sulfonate, accounting for 0.2% - 10% of the total mass of the composition; (D) Alkyl diphenylamine, accounting for 0.05% - 5% of the total mass of the composition; (E) Hydrogenated styrene-isoprene copolymer, accounting for 0.1% - 3% of the total mass of the composition; (F) A major amount of lubricating oil base oil; Wherein the phosphate salt includes a structural unit shown in formula (1), and at least one of the structural units shown in formula (2), formula (3) and formula (4), Wherein, R1 and R2 are each independently selected from hydrogen, hydrocarbon group, substituted hydrocarbon group or heteroalkyl group; Wherein, X1 is selected from nitrogen or methylene, R and R' are each independently selected from hydrogen or a C1-C4 hydrocarbon group; R3, R4 and R5 are each independently selected from a C1-C5 hydrocarbon group, and r1 and r2 are each independently 0 or 1; Wherein, R6, R7 and R8 are each independently selected from C1-C5 hydrocarbon groups, and r3 and r4 are each independently 0 or 1; Among them, R” is selected from hydrogen or a C1-C4 hydrocarbon group, and R9, R 10 and R 11 are each independently selected from C1-C5 hydrocarbon groups, and r5 and r6 are each independently 0 or 1.

2. The four-stroke UAV engine lubricating oil composition according to claim 1, characterized in that, In formula (1), R1 and R2 are not both hydrogen at the same time; Preferably, R1 and R2 are each independently selected from a C4-C18 hydrocarbon group, a C4-C18 hydroxy-substituted hydrocarbon group or a C3-C20 heteroalkyl group; Preferably, the heteroatom in the heteroalkyl group is at least one of O, N and S, preferably O and / or S, and more preferably S.

3. The four-stroke UAV engine lubricating oil composition according to claim 2, characterized in that R1 and R2 are each independently selected from n-butyl, isobutyl, tert-butyl, n-hexyl, 2-ethylhexyl, n-octyl, 1-methylheptyl, 3,5,5-trimethylhexyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl, 9-octadecenyl, 9,12-octadecadienyl, 12-hydroxy-9-octadecenyl, cyclohexyl, phenyl, benzyl, methylphenyl or dimethylphenyl.

4. The four-stroke UAV engine lubricating oil composition according to claim 1, characterized in that In formulas (2)-(4), R3, R6, and R9 are each independently -(CH2) a -, where a is selected from 2-5; and / or, R4, R7, R 10 each independently is -(CH2) b -, where b is 1 - 2; and / or, R5, R8, R 11 each independently is -(CH2) c -, where c is 1 - 3.

5. The four-stroke drone engine lubricating oil composition according to claim 1, characterized in that, The preparation method of the phosphate salt includes: Contacting an acidic phosphate having a structure shown in formula (5) with a nitrogen-containing organic compound having a bicyclic structure to carry out a phosphate salt formation reaction; Wherein, R1 and R2 are each independently selected from hydrogen, a hydrocarbon group, a substituted hydrocarbon group or a heteroalkyl group; Wherein the nitrogen-containing organic compound has at least one of the structures shown in formula (6), formula (7) and formula (8), Wherein, X1 is selected from nitrogen or methylene, R and R' are each independently selected from hydrogen or a C1-C4 hydrocarbon group; R3, R4 and R5 are each independently selected from a C1-C5 hydrocarbon group, and r1 and r2 are each independently 0 or 1; Wherein, R6, R7 and R8 are each independently selected from C1-C5 hydrocarbyl groups, and r3 and r4 are each independently 0 or 1; Among them, R” is selected from hydrogen or a C1-C4 hydrocarbon group, R9, R 10 and R 11 are each independently selected from C1-C5 hydrocarbon groups, and r5 and r6 are each independently 0 or 1.

6. The four-stroke UAV engine lubricating oil composition according to claim 5, characterized in that, In formula (5), R1 and R2 are not both hydrogen at the same time; Preferably, R1 and R2 are each independently selected from a C4-C18 hydrocarbon group, a C4-C18 hydroxy-substituted hydrocarbon group or a C3-C20 heteroalkyl group; Preferably, the heteroatom in the heteroalkyl group is at least one of O, N and S, preferably O and / or S, and more preferably S; Preferably, R1 and R2 are each independently selected from n-butyl, isobutyl, tert-butyl, n-hexyl, 2-ethylhexyl, n-octyl, 1-methylheptyl, 3,5,5-trimethylhexyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl, 9-octadecenyl, 9,12-octadecadienyl, 12-hydroxy-9-octadecenyl, cyclohexyl, phenyl, benzyl, methylphenyl or dimethylphenyl.

7. The four-stroke UAV engine lubricating oil composition according to claim 5, characterized in that, In Formula (6) - Formula (8), R3, R6, and R9 are each independently -(CH2) a -, where a is selected from 2 - 5; and / or, R4, R7, R 10 each independently is -(CH2) b -, where b is 1 - 2; and / or, R5, R8, R 11 each independently is -(CH2) c -, where c is 1 - 3.

8. The four-stroke UAV engine lubricating oil composition according to claim 5, characterized in that, The molar ratio of the acidic phosphate to the nitrogen-containing organic compound is 1:0.1 - 10, preferably 1:0.4 - 5, and more preferably 1:0.5 - 2; Preferably, the conditions for the phosphate salt formation reaction include: the reaction temperature is 0 - 200 °C, preferably 20 - 150 °C, more preferably 60 - 120 °C, and the reaction time is 0.1 - 24 h, preferably 0.5 - 12 h, more preferably 1 - 5 h.

9. The four-stroke UAV engine lubricating oil composition according to any one of claims 1-8, characterized in that The number-average molecular weight of the polyisobutylene group in the polyisobutylene succinimide is 1,000 to 4,000; the sulfonate is selected from sulfonates with a base number of 20 to 450 mg KOH / g; the alkyl in the alkyl diphenylamine is a C 4～10 linear or branched alkyl; the hydrogenated styrene-isoprene copolymer is selected from hydrogenated styrene-isoprene copolymers with a number-average molecular weight of 60,000 to 600,000; the lubricating oil base oil is selected from mineral base oils and / or synthetic base oils.

10. The preparation method of the four-stroke UAV engine lubricating oil composition according to any one of claims 1 to 9, comprising the step of mixing various additives and lubricating oil base oil therein.

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