Electric vehicle transmission lubricating oil composition and preparation method thereof

Abstract

This invention discloses an electric vehicle transmission lubricating oil composition and its preparation method. The electric vehicle transmission lubricating oil composition comprises the following components: (A) an ashless dispersant, accounting for 1.0% to 5.0% of the total mass of the composition; (B) a viscosity index improver, accounting for 0.5% to 5.0% of the total mass of the composition; (C) an antioxidant, accounting for 0.1% to 3.0% of the total mass of the composition; (D) a metal deactivator, accounting for 0.01% to 0.3% of the total mass of the composition; (E) a phosphate ester salt, accounting for 0.2% to 2.0% of the total mass of the composition; and (F) a base oil, constituting the main component of the composition. The electric vehicle transmission lubricating oil composition of this invention possesses both low viscosity, excellent copper corrosion resistance, and high anti-wear and load-bearing properties.

Description

Technical Field

[0001] This invention relates to the field of lubricating oils, and in particular to a lubricating oil composition for electric vehicle transmissions and its preparation method. Background Technology

[0002] Unlike traditional gasoline-powered vehicles, electric vehicles use electric motors instead of engines, thus placing new demands on the performance of their lubricating oils. The technological development requirements of electric vehicles—smaller, lighter, and lower energy consumption—have led to a trend towards integrated design of their motors and transmission systems. This means that the motor and reducer share a single lubrication system, a development trend for electric vehicle lubricating oils. Simultaneously, to improve the transmission efficiency of electric vehicles, lower viscosity oils are required. Currently, most electric vehicles on the market use a single-speed reduction structure, with the motor directly driving the transmission. The maximum speed of the motor can reach over 20,000 rpm, and this high input speed places stringent requirements on the wear resistance and load-bearing capacity of the transmission. Furthermore, the motor structure contains a large number of copper components, thus requiring electric vehicle lubricating oils to have excellent copper corrosion resistance.

[0003] Low-viscosity oils typically form a thinner oil film during use, which is detrimental to their anti-wear and load-bearing properties. Therefore, improving these properties requires the use of high-performance extreme pressure anti-wear agents. However, in formulated oils, extreme pressure anti-wear agents and corrosion inhibitors compete for adsorption on metal surfaces. In particular, extreme pressure anti-wear agents with high sulfur content can cause severe corrosion to copper components.

[0004] CN111808658A discloses a lubricating oil composition containing phosphite and thiadiazole compounds, which improves the sintering resistance and fatigue resistance of electric motors and transmissions, but does not investigate the effect of additives on copper corrosion resistance.

[0005] CN108218835A discloses a method for preparing a sulfur-nitrogen heterocyclic extreme pressure anti-wear agent and its application in transmission fluid for new energy vehicles. This extreme pressure anti-wear agent has a low dosage and good extreme pressure anti-wear performance, which reduces the cost of transmission fluid. However, the introduction of sulfur into this extreme pressure anti-wear agent causes significant corrosion to copper components.

[0006] The above literature has improved the extreme pressure anti-wear performance of low-viscosity oils by introducing phosphorus-based, sulfur-based, or sulfur-nitrogen-based extreme pressure anti-wear agents, but it is difficult to simultaneously ensure the oil's resistance to copper corrosion. Therefore, how to achieve a balanced approach to low viscosity, excellent copper corrosion resistance, and anti-wear load-bearing performance is the key to the development of electric vehicle oils. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention proposes an electric vehicle transmission lubricant composition and its preparation method that combines low viscosity, excellent copper corrosion resistance, and anti-wear and load-bearing performance.

[0008] The electric vehicle transmission lubricant composition of the present invention comprises the following components:

[0009] (A) Ash-free dispersant, accounting for 1.0% to 5.0% of the total mass of the composition;

[0010] (B) Viscosity index improver, accounting for 0.5% to 5.0% of the total mass of the composition;

[0011] (C) Antioxidant, comprising 0.1% to 3.0% of the total mass of the composition;

[0012] (D) Metal deactivator, accounting for 0.01% to 0.3% of the total mass of the composition;

[0013] (E) Phosphate salt, comprising 0.2% to 2.0% of the total mass of the composition;

[0014] (F) Base oil, which constitutes the main component of the composition;

[0015] The phosphate salt comprises at least one of the structural units shown in formula (1), and formulas (2), (3) and (4).

[0016] R1 and R2 are each independently selected from hydrogen, hydrocarbon group, substituted hydrocarbon group or heteroalkyl group;

[0017] Wherein, X1 is selected from nitrogen or methine, R and R' are each independently selected from hydrogen or C1-C4 hydrocarbon groups; R3, R4 and R5 are each independently selected from C1-C5 hydrocarbon groups, and r1 and r2 are each independently 0 or 1.

[0018] Among them, R6, R7 and R8 are each independently selected from C1-C5 hydrocarbon groups, and r3 and r4 are each independently 0 or 1;

[0019] Wherein, R” is selected from hydrogen or C1-C4 hydrocarbon groups, R9, R 10 and R 11 Each r5 and r6 is independently selected from C1-C5 hydrocarbon groups, and each r5 and r6 is independently 0 or 1.

[0020] According to the present invention, the method for preparing the phosphate salt includes:

[0021] An acidic phosphate ester having the structure shown in formula (5) is brought into contact with a nitrogen-containing organic compound having a bicyclic structure to react with the phosphate salt.

[0022] R1 and R2 are each independently selected from hydrogen, hydrocarbon group, substituted hydrocarbon group or heteroalkyl group;

[0023] The nitrogen-containing organic compound has at least one of the structures shown in formula (6), formula (7) and formula (8).

[0024] Wherein, X1 is selected from nitrogen or methine, R and R' are each independently selected from hydrogen or C1-C4 hydrocarbon groups; R3, R4 and R5 are each independently selected from C1-C5 hydrocarbon groups, and r1 and r2 are each independently 0 or 1.

[0025] Among them, R6, R7 and R8 are each independently selected from C1-C5 hydrocarbon groups, and r3 and r4 are each independently 0 or 1;

[0026] Wherein, R” is selected from hydrogen or C1-C4 hydrocarbon groups, R9, R 10 and R 11 Each r5 and r6 is independently selected from C1-C5 hydrocarbon groups, and each r5 and r6 is independently 0 or 1.

[0027] According to the present invention, the phosphate salt contains no metal elements, is not prone to ash generation, and exhibits significant anti-wear properties at relatively small dosages, effectively improving the anti-wear performance and load-carrying capacity of lubricating oils. Furthermore, when used as an anti-wear additive for lubricating oils, the phosphate salt exhibits excellent anti-wear properties while exhibiting low metal corrosivity.

[0028] According to the present invention, the ashless dispersant may be selected from polyisobutylene succinimide and / or boronized polyisobutylene succinimide, for example, one or more of monoisobutylene succinimide, diisobutylene succinimide, high molecular weight polyisobutylene succinimide and boronized diisobutylene succinimide may be selected, and common commercial brands include T151, T154, T161, T154B, etc.

[0029] According to the present invention, the viscosity index improver can be selected from polymethacrylate and / or polyisobutylene, and common commercial brands include Viscoplex 8-219, TK-Chem6350, Viscoplex 8-310, PIB1400, etc., preferably with a kinematic viscosity of 500-1500 mmHg at 100°C. 2 / s of polymethyl methacrylate and / or polyisobutylene with a number average molecular weight of 1000 to 3400.

[0030] According to the present invention, the antioxidant may be selected from one or more of alkylated diphenylamine, N-phenyl-α-naphthylamine, shielding phenol and phenolic ester, for example, one or more of dibutyldiphenylamine, dioctyldiphenylamine, butyl / octyldiphenylamine, bis(dodecyl)diphenylamine, bis(pentyl)diphenylamine, 2,6-di-tert-butyl-p-cresol and 2,6-di-tert-butyl-4-hydroxyphenylpropionate, common commercial brands include T534, T531, T501, etc.

[0031] According to the present invention, the metal deactivator is selected from one or more of alkylaminomethylenetriazole, triazole dialkylamine formaldehyde condensate, thiadiazole polysulfide and thiadiazole alkyl thiol hydrogen peroxide condensate, and common commercial brands include T551, T552, T553, T571, T561, etc.

[0032] According to the present invention, the base oil may be selected from one or more of API Group I, II, III, IV and V base oils, for example, one or more of Group I base oils, Group II hydrotreated base oils, Group III hydrotreated base oils, polyalphaolefins, alkylbenzenes and alkylnaphthalenes, preferably one or more of Group I base oils, Group II hydrotreated base oils, Group III hydrotreated base oils and polyalphaolefins, and more preferably a kinematic viscosity of 1 to 10 mm at 100°C. 2 The base oil is further preferably selected to have a kinematic viscosity of 3-6 mm at 100°C. 2 / s of base oil.

[0033] The method for preparing the electric vehicle transmission lubricating oil composition of the present invention includes the step of mixing various additives and base oils therein.

[0034] The electric vehicle transmission lubricant composition of the present invention has the advantages of low viscosity, excellent copper corrosion resistance and high anti-wear and load-bearing properties. Detailed Implementation

[0035] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0036] The present invention will be further described in detail below with reference to embodiments. However, the present invention is not limited thereto. Unless otherwise stated, all proportions and quantities are calculated by mass.

[0037] A first aspect of the present invention provides a phosphate salt comprising at least one of the structural units shown in formula (1) and formulas (2), (3) and (4).

[0038] R1 and R2 are each independently selected from hydrogen, hydrocarbon group, substituted hydrocarbon group or heteroalkyl group;

[0039] Wherein, X1 is selected from nitrogen or methine, R and R' are each independently selected from hydrogen or C1-C4 hydrocarbon groups; R3, R4 and R5 are each independently selected from C1-C5 hydrocarbon groups, and r1 and r2 are each independently 0 or 1.

[0040] Among them, R6, R7 and R8 are each independently selected from C1-C5 hydrocarbon groups, and r3 and r4 are each independently 0 or 1;

[0041] Wherein, R” is selected from hydrogen or C1-C4 hydrocarbon groups, R9, R 10 and R 11 Each r5 and r6 is independently selected from C1-C5 hydrocarbon groups, and each r5 and r6 is independently 0 or 1.

[0042] In existing technologies, the use of phosphate ester amine salts as anti-wear additives in lubricating oils typically requires high dosages. Through continuous research, the inventors of this invention have discovered that phosphate ester organic base salts with a nitrogen-containing bicyclic structure can exhibit significant anti-wear properties at relatively low dosage levels, effectively improving the anti-wear performance and load-carrying capacity of lubricating oils. These phosphate ester salts are free of metal elements, do not easily generate ash, and exhibit excellent anti-wear properties while exhibiting low metal corrosivity, representing a significant advancement compared to existing phosphate ester amine salt compounds.

[0043] In this 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.

[0044] Wherein, "hydrocarbon group" has the meaning conventionally known in the art, including but not limited to straight-chain or branched alkyl, straight-chain or branched alkenyl, straight-chain or branched alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, or combinations thereof. Preferably, the hydrocarbon group is a C1-C20 hydrocarbon group, including but not limited to C1-C20 straight-chain or branched alkyl, C2-C20 straight-chain or branched alkenyl, C2-C20 straight-chain or branched alkynyl, C3-C20 cycloalkyl, C3-C20 cycloalkenyl, C3-C20 cycloalkynyl, C6-C20 aryl, or combinations thereof.

[0045] In this invention, the term "substituted hydrocarbon group" refers to a group obtained by directly replacing one or more hydrogen atoms in a hydrocarbon molecule with a substituent, wherein the substituent includes, but is not limited to, at least one of fluorine atom, chlorine atom, bromine atom, hydroxyl group, mercapto group, alkoxy group and alkyl thio group.

[0046] In this invention, "heteroalkyl" refers to a group obtained by directly replacing one or more carbon atoms within the alkyl molecule structure (excluding the ends of the main chain or any side chains in the alkyl molecule structure) with heteroatoms. It is understood that, from a structural stability perspective, when multiple heteroatoms are present, these heteroatoms do not directly bond to each other. Although the number of carbon atoms in the alkyl group is reduced due to the substitution of carbon atoms with heteroatoms in this invention, for the sake of simplicity, the number of carbon atoms in the alkyl group that has been replaced is still used to refer to the number of carbon atoms in the heteroalkyl group.

[0047] For example, C4 straight-chain alkyl groups, such as (The group indicated by the arrow is at the end of the main chain) Direct substitution with a substituent group -O- will yield -CH2-O-CH2-CH3 or -CH2-CH2-O-CH3, referred to as a C4 straight-chain heteroalkyl group. Alternatively, a C4 branched alkyl group, such as... (The group indicated by the arrow in the formula is not inside the molecular structure, but at the end of the main chain and side chain.) The methine group in ( ) being directly replaced by a substituent group -N< will yield This is referred to as a C4 branched heteroalkyl group. According to the present invention, the heteroalkyl group includes, but is not limited to, straight-chain or branched heteroalkyl groups of C3-C20, preferably straight-chain or branched heteroalkyl groups of C3-C10.

[0048] 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.

[0049] According to the present invention, preferably, R1 and R2 are each independently selected from C4-C18 hydrocarbon groups, C4-C18 hydroxy-substituted hydrocarbon groups, or C3-C20 heteroalkyl groups, 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.

[0050] 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 in this case, the N and C atoms 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 in this case, the N and X1 on both sides of R5 in formula (2) are directly connected. The meanings of r3, r4, r5 and r6 in formulas (3) and (4) are the same as those of r1 and r2, and will not be repeated here.

[0051] In this invention, the anti-wear performance of lubricating oil can be improved as long as the phosphate salt contains phosphate groups and a nitrogen-containing bicyclic structure. The anti-wear performance and metal corrosion resistance can be further optimized by controlling the size (carbon number) of the bicyclic structure. For example, the size of the bicyclic structure in formula (2) can be controlled by adjusting the main chain carbon number of groups R3, R4, and R5. Similarly, in the structures shown in formulas (3) and (4), the size of the bicyclic structure in formula (2) can be controlled by adjusting groups R6, R7, R8, R9, and R1, respectively. 10 and R 11 The number of carbon atoms in the main chain of the group can control the size of the bicyclic structure in formulas (2) and (3).

[0052] According to the present invention, preferably, in formulas (2)-(4), R3, R6, and R9 are each independently -(CH2). a , where a is selected from 2-5.

[0053] According to the present invention, preferably, R4, R7, R 10 Each is independently -(CH2) b - where b is 1-2.

[0054] According to the present invention, preferably, R5, R8, R 11 Each is independently -(CH2) c , where c is 1-3.

[0055] By selecting the ring number and stereostructure of the nitrogen-containing organic compounds mentioned above, it is possible to control the alkalinity of such compounds and their dispersibility in base oils, and to select nitrogen-containing organic compounds with sufficiently stable chemical properties according to the usage environment.

[0056] According to the present invention, the phosphate salt can exist, be manufactured or used in the form of a single (pure) compound, or in the form of a mixture of two or more of them (in any proportion), without affecting the realization of the effects of the present invention.

[0057] 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 method known in the art.

[0058] A second aspect of the present invention provides a method for preparing the phosphate salt, the method comprising:

[0059] An acidic phosphate ester having the structure shown in formula (5) is brought into contact with a nitrogen-containing organic compound having a bicyclic structure to react with the phosphate salt.

[0060] R1 and R2 are each independently selected from hydrogen, hydrocarbon group, substituted hydrocarbon group or heteroalkyl group;

[0061] The nitrogen-containing organic compound has at least one of the structures shown in formula (6), formula (7) and formula (8).

[0062] Wherein, X1 is selected from nitrogen or methine, R and R' are each independently selected from hydrogen or C1-C4 hydrocarbon groups; R3, R4 and R5 are each independently selected from C1-C5 hydrocarbon groups, and r1 and r2 are each independently 0 or 1.

[0063] Among them, R6, R7 and R8 are each independently selected from C1-C5 hydrocarbon groups, and r3 and r4 are each independently 0 or 1;

[0064] Wherein, R” is selected from hydrogen or C1-C4 hydrocarbon groups, R9, R 10 and R 11 Each r5 and r6 is independently selected from C1-C5 hydrocarbon groups, and each r5 and r6 is independently 0 or 1.

[0065] In this invention, the acidic phosphate ester can be a commercially available product or manufactured using methods conventionally known in the art; there are no particular limitations on this. Furthermore, only one type of acidic phosphate ester can be used, or two or more can be used in combination, as long as the structure shown in formula (5) is satisfied.

[0066] According to the present invention, preferably, in formula (5), R1 and R2 are not both hydrogen.

[0067] Preferably, R1 and R2 are each independently selected from C4-C18 hydrocarbon groups, C4-C18 hydroxy-substituted hydrocarbon groups, or C3-C20 heteroalkyl groups.

[0068] 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.

[0069] 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.

[0070] According to the present invention, the acidic phosphate esters include, but are 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), monohexyl phosphate (CAS: 3900-04-7), and dihexyl 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, Mono-n-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), mono-n-decyl phosphate (CAS: 3921-30-0), di-n-decyl phosphate (CAS: 7795-87-1) At least one of the following compounds, or isomers of the above compounds: monolauryl phosphate, dilauryl phosphate, monomyristyl phosphate, dimyristyl phosphate, mono(hexadecyl) phosphate, di(hexadecyl) phosphate, monostearyl phosphate, distearate 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.

[0071] The present invention does not particularly limit the source of the nitrogen-containing organic compound with the bicyclic structure. Commercially available products can be used directly, or it can be manufactured by methods conventionally known in the art. The nitrogen-containing organic compound can be used alone, or two or more can be used in combination, as long as it satisfies at least one of the structures shown in formulas (6), (7) and (8).

[0072] According to the present invention, preferably, in formulas (6)-(8), R3, R6, and R9 are each independently -(CH2). a , where a is selected from 2-5.

[0073] Preferably, R4, R7, R 10 Each is independently -(CH2) b - where b is 1-2.

[0074] Preferably, R5, R8, R 11 Each is independently -(CH2) c , where c is 1-3.

[0075] According to the present invention, the nitrogen-containing organic compounds include, but are not limited to, 1,4-diazabicyclo[2.2.2]octane (CAS: 280-57-9), 1-diazabicyclo[2.2.2]octane (quinine ring, 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 (abbreviated as DBU, CAS: 6674-22-2), and any mixture of the above compounds in any proportion.

[0076] In this invention, preferably, the molar ratio of the acidic phosphate ester to the nitrogen-containing organic compound is 1:0.1-10, more preferably 1:0.4-5, and more preferably 1:0.5-2.

[0077] The present invention provides a wide range of reaction temperatures for the reaction of the phosphate salt. Preferably, the reaction temperature is 0-200℃, more preferably 20-150℃, and even more preferably 60-120℃. The present invention does not have any particular requirements for the reaction time. In order to ensure a complete reaction, the reaction time is preferably 0.1-24h, more preferably 0.5-12h, and even more preferably 1-5h.

[0078] The present invention does not have any particular limitation on the reaction pressure and atmosphere for the reaction of the phosphate salt, and can be carried out under normal pressure and air conditions.

[0079] According to the present invention, the phosphate salt reaction can be carried out in the presence of a solvent or not, and the reaction can be achieved either way. Preferably, the phosphate salt reaction is carried out in the presence of a solvent. For example, acidic phosphate and nitrogen-containing organic matter are added to a reactor containing a solvent for contact, or acidic phosphate and nitrogen-containing organic matter are dissolved separately in a solvent, and then both are added to the reactor to carry out the phosphate salt reaction. The present invention does not have special requirements for the reactor, as long as the reaction conditions can be controlled within the above-mentioned range. Conventional reaction apparatus in the art can be used in the present invention.

[0080] The present invention does not have any special requirements for the specific operating conditions for adding the above-mentioned reactants to the reactor. Conventional operating methods in the art can be used. Preferably, the reactants are slowly added to the reactor in batches or dropwise, and the temperature is controlled within the above-mentioned reaction temperature range.

[0081] This invention does not impose any special restrictions on the order in which the reactants are added; they can be added in any order.

[0082] 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; and the C3-C10 amides include, but are not limited to, at least one of dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

[0083] According to the present invention, preferably, the mass ratio of the total mass of the acidic phosphate ester and the nitrogen-containing organic compound to the mass of the solvent is 1:0.5-10, more preferably 1:0.5-5, and more preferably 1:0.8-3.

[0084] According to the present invention, only one solvent may be used, or a combination of two or more solvents may be used. Preferably, the preparation method further includes recovering the solvent after the reaction and reusing it in the same reaction. For example, the solvent can be recovered by vacuum distillation.

[0085] According to the present invention, in the method for preparing the phosphate salt, the reaction product obtained can be a single phosphate salt or a mixture containing multiple phosphate salts. These reaction products are all intended for the present invention, and the phosphate salts all have at least one of the structural units shown in formula (1), and formulas (2), (3) and (4). The difference in their specific 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.

[0086] Therefore, in this invention, the product obtained from the reaction of the phosphate salt can be purified, or it can be left unpurified. To further improve the performance of the phosphate salt, preferably, the preparation method further includes purifying the product obtained from the reaction of the phosphate salt. Through this purification, a phosphate salt with a specific structure is separated from the product obtained from the reaction of the phosphate salt.

[0087] The purification can be carried out using any conventional purification or separation method in the art, and the present invention does not have any particular limitation in this regard. For example, column chromatography or preparative chromatography can be used to purify the reaction product.

[0088] The present invention will be described in detail below through embodiments.

[0089] Unless otherwise specified, all raw materials used in the following examples and comparative examples are commercially available.

[0090] Example 1

[0091] In a 250 mL three-necked flask equipped with a magnetic stirrer, thermometer, condenser, and 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 dissolved by stirring at room temperature. 25.02 g (100.00 mmol) of diphenyl phosphate was dissolved in 49.09 g of 1,2-dimethoxyethane and slowly added dropwise to the three-necked flask. The temperature was raised to 85 °C and refluxed for 4.5 hours, maintaining the temperature between 80-85 °C. After the reaction, the solvent was removed by vacuum distillation, yielding 30.48 g of a white waxy product. This product was designated S1. The structure of the product was characterized by chromatography-mass spectrometry, and the molecular weight of the main product was determined to be 350.12. The structure of the main product in S1 is shown in the following formula:

[0092]

[0093] Example 2

[0094] In a 250 mL three-necked flask equipped with a magnetic stirrer, thermometer, condenser, and 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 at room temperature to dissolve. 32.21 g (99.90 mmol) of di(2-ethylhexyl) phosphate was slowly added dropwise to the flask, and the temperature was raised to 85 °C. The mixture was then refluxed at 80-85 °C for 4 hours. After the reaction, the solvent was removed by vacuum distillation, yielding 37.32 g of a white waxy product. This product was designated S2. The structure of the product was characterized by chromatography-mass spectrometry, and the molecular weight of the main product was determined to be 434.38. The structure of the main product in S2 is shown in the following formula:

[0095]

[0096] Example 3

[0097] In a 250 mL three-necked flask equipped with a magnetic stirrer, thermometer, condenser, and dropping funnel, 5.61 g (50.13 mmol) of 1,4-diazabicyclo[2.2.2]octane and 45.52 g of 1,2-dimethoxyethane were added and rapidly stirred at room temperature to dissolve. 21.04 g (100.01 mmol) of di-n-butyl phosphate was slowly added dropwise to the flask, and the temperature was raised to 85 °C. The mixture was then refluxed at 80-85 °C for 4 hours. After the reaction, the solvent was removed by vacuum distillation, yielding 26.06 g of a pale yellow, clear, transparent oily liquid product. This product was designated S3. The structure of the product was characterized by chromatography-mass spectrometry, and the molecular weight of the main product was determined to be 321.99. The structure of the main product in S3 is shown in the following formula:

[0098]

[0099] Example 4

[0100] In a 250 mL three-necked flask equipped with a magnetic stirrer, thermometer, condenser, and dropping funnel, 12.50 g (49.96 mmol) of diphenyl phosphate and 25.36 g of 1,2-dimethoxyethane were added and rapidly stirred at room temperature to dissolve. 3.84 g (25.22 mmol) of 1,8-diazabicyclo[5.4.0]undec-7-ene was slowly added dropwise to the flask. The temperature was raised to 95 °C, and the mixture was refluxed at 85-90 °C for 4.5 hours. After the reaction, the solvent was removed by vacuum distillation, yielding 16.14 g of a pale yellow, clear, transparent viscous product. This product was designated S4. The structure of the product was characterized by chromatography-mass spectrometry, and the molecular weight of the main product was determined to be 402.89. The structure of the main product in S4 is shown in the following formula:

[0101]

[0102] Example 5

[0103] In a 250 mL three-necked flask equipped with a magnetic stirrer, thermometer, condenser, and dropping funnel, 16.17 g (50.15 mmol) of di(2-ethylhexyl) phosphate and 19.92 g of petroleum ether (60-90 °C) were added and dissolved by stirring at room temperature. 3.81 g (25.03 mmol) of 1,8-diazabicyclo[5.4.0]undec-7-ene was slowly added dropwise to the flask, and the temperature was raised to 85 °C. The mixture was then refluxed at 65-75 °C for 4 hours. After the reaction, the solvent was removed by vacuum distillation, yielding 19.92 g of a pale yellow, clear, transparent oily liquid product. This product was designated S5. The structure of the product was characterized by chromatography-mass spectrometry, and the molecular weight of the main product was determined to be 474.56. The structure of the main product in S5 is shown in the following formula:

[0104]

[0105] Comparative Example 1: Diphenyl Phosphate Laurylamine Salt Anti-wear Agent

[0106] The raw materials used were commercially available diphenyl phosphate and laurylamine. Diphenyl phosphate was dissolved in 1,2-dimethoxyethane at a mass ratio of 1:2. Laurylamine was dissolved in petroleum ether at 60-90°C at a mass ratio of 1:1. The laurylamine solution was slowly added dropwise to the diphenyl phosphate solution with stirring, maintaining a molar ratio of 1:1 between diphenyl phosphate and laurylamine. The mixture was heated to 85°C and refluxed at 70-80°C for 4 hours. After the reaction was complete, the solvent was evaporated to obtain the product, denoted as DS1, whose main component was diphenyl phosphate laurylamine salt, with the structure shown below:

[0107]

[0108] Comparative Example 2: Di(2-ethylhexyl) phosphate di-n-hexylamine salt anti-wear agent

[0109] The raw materials used were commercially available di(2-ethylhexyl) phosphate and di-n-hexylamine. Di(2-ethylhexyl) phosphate was dissolved in petroleum ether at 60-90℃, with a mass ratio of di(2-ethylhexyl) phosphate to petroleum ether at 60-90℃ of 1:1. Di-n-hexylamine was slowly added dropwise to the di(2-ethylhexyl) phosphate solution with stirring, with a molar ratio of di(2-ethylhexyl) phosphate to di-n-hexylamine of 1:1. The mixture was heated to 85℃ and refluxed at 75-80℃ for 4 hours. After the reaction was complete, the solvent was evaporated to obtain the product, denoted as DS2, whose main component was the di-n-hexylamine salt of di(2-ethylhexyl) phosphate, with the structure shown below:

[0110]

[0111] Comparative Example 3: Di-n-butyl phosphate di-n-hexylamine salt anti-wear agent

[0112] The raw materials used were commercially available di-n-butyl phosphate and di-n-hexylamine. Di-n-butyl phosphate was dissolved in petroleum ether at 60-90℃, with a mass ratio of di-n-butyl phosphate to petroleum ether of 1:1. Di-n-hexylamine was slowly added dropwise to the di-n-butyl phosphate solution with stirring, maintaining a molar ratio of di-n-butyl phosphate to di-n-hexylamine of 1:1. The mixture was heated to 85℃ and refluxed at 75-80℃ for 4 hours. After the reaction was complete, the solvent was evaporated to obtain the product, denoted as DS3, whose main component was di-n-butyl phosphate di-n-hexylamine salt, with the structure shown below:

[0113]

[0114] Comparative Example 4 uses BASF's Irgalube 349.

[0115] Examples I-1 to I-5 and Comparative Examples DI-1 to DI-4 of electric vehicle transmission lubricant compositions

[0116] According to the formulations in Table 1, Examples I-1 to I-5 and Comparative Examples DI-1 to DI-4 of electric vehicle transmission lubricating oil compositions were prepared respectively. The main additives and base oils used were sourced from the following sources:

[0117] Diisobutylene succinimide T154A, dispersibility SDT≥55, produced by Yangzi Petrochemical Company;

[0118] Viscoplex 8-310, a non-dispersible PMA viscosity index improver, has a kinematic viscosity of 1250 mmHg at 100°C. 2 / s, manufactured by Evonik Degussa;

[0119] Amine-type antioxidant T534, nitrogen content >3.0%, kinematic viscosity 10.0 mm at 100°C. 2 / s, produced by Beijing Xingpu Fine Chemical Technology Development Co., Ltd.;

[0120] Phenolic antioxidant T512, kinematic viscosity at 100℃: 7.0 mm. 2 / s, produced by Beijing Xingpu Fine Chemical Technology Development Co., Ltd.;

[0121] Benzotriazole derivative T551, kinematic viscosity at 100°C, 12.5 mm. 2 / s, produced by Zibo Huihua Petroleum Additives Company;

[0122] Irgalube 349, viscosity at 40°C is 2200 mPa·s, BASF.

[0123] Group III hydrotreated base oil, kinematic viscosity at 100°C 4.45 mm. 2 / s, viscosity index 125, produced by Maoming Petrochemical.

[0124] Table 1 Lubricating Oil Compositions for Electric Vehicle Transmissions

[0125]

[0126] The kinematic viscosity, load-bearing capacity, and copper corrosion test performance of the above-mentioned electric vehicle transmission lubricant compositions were evaluated in both the examples and comparative examples.

[0127] The main experimental methods are as follows:

[0128] The method for determining kinematic viscosity is the standard method of GB / T 265;

[0129] Four-ball wear and extreme pressure tests shall be conducted using the standard method of GB / T 3142.

[0130] The Falex extreme pressure performance test adopts the SH / T 0187 standard method;

[0131] FZG gear test, A10 / 16.6R / 90℃, using the ISO 14635-2 standard method;

[0132] The copper corrosion test was conducted using the standard method of GB / T 5096, with test conditions of 150℃ and 192h.

[0133] The measurement results are shown in Table 2.

[0134] Table 2 Evaluation Test Results of Electric Vehicle Transmission Lubricating Oil

[0135]

[0136] The above test results show that the lubricating oil composition of the present invention can meet the requirements of low viscosity oil, while having high load-bearing capacity and excellent copper corrosion resistance.

[0137] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A transmission lubricant composition for electric vehicles, comprising the following components: (A) Ash-free dispersant, accounting for 1.0% to 5.0% of the total mass of the composition; (B) Viscosity index improver, accounting for 0.5% to 5.0% of the total mass of the composition; (C) Antioxidant, comprising 0.1% to 3.0% of the total mass of the composition; (D) Metal deactivator, accounting for 0.01% to 0.3% of the total mass of the composition; (E) Phosphate salt, comprising 0.2% to 2.0% of the total mass of the composition; (F) Base oil, which constitutes the main component of the composition; The phosphate salt comprises at least one of the structural units shown in formula (1) and formulas (3) and (4). in, R1 and R2 are each independently selected from hydrocarbon groups; Among them, R6, R7 and R8 are each independently selected from C1-C5 hydrocarbon groups, r3 is 0 and r4 is 1; Wherein, R” is selected from hydrogen or C1-C4 hydrocarbon groups, R9, R 10 and R 11 Each is independently selected from C1-C5 hydrocarbon groups, with r5 and r6 both being 1.

2. The lubricating oil composition according to claim 1, characterized in that, R1 and R2 are each independently selected from C4-C18 hydrocarbon groups.

3. The 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, cyclohexyl, phenyl, benzyl, methylphenyl, or dimethylphenyl.

4. The lubricating oil composition according to claim 1, characterized in that, In equations (3)-(4), R6 and R9 are each independently -(CH2). a -, where a is selected from 2-5; And / or, R7, R 10 Each is independently -(CH2) b - where b is 1-2; And / or, R8, R 11 Each is independently -(CH2) c - where c is 1-3.

5. The lubricating oil composition according to claim 1, characterized in that, The method for preparing the phosphate salt includes: An acidic phosphate ester having the structure shown in formula (5) is brought into contact with a nitrogen-containing organic compound having a bicyclic structure to react with the phosphate salt. R1 and R2 are each independently selected from hydrocarbon groups; The nitrogen-containing organic compound has at least one of the structures shown in formula (7) and formula (8). Among them, R6, R7 and R8 are each independently selected from C1-C5 hydrocarbon groups, r3 is 0 and r4 is 1; Wherein, R” is selected from hydrogen or C1-C4 hydrocarbon groups, R9, R 10 and R 11 Each is independently selected from C1-C5 hydrocarbon groups, with r5 and r6 both being 1.

6. The lubricating oil composition according to claim 5, characterized in that, In formula (5), R1 and R2 are each independently selected from C4-C18 hydrocarbon groups.

7. The lubricating oil composition according to claim 6, 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, cyclohexyl, phenyl, benzyl, methylphenyl, or dimethylphenyl.

8. The lubricating oil composition according to claim 5, characterized in that, In equations (7)-(8), R6 and R9 are each independently -(CH2). a -, where a is selected from 2-5; And / or, R7, R 10 Each is independently -(CH2) b - where b is 1-2; And / or, R8, R 11 Each is independently -(CH2) c - where c is 1-3.

9. The lubricating oil composition according to claim 5, characterized in that, The molar ratio of the acidic phosphate ester to the nitrogen-containing organic matter is 1:0.1-10; the reaction conditions for the phosphate ester salt include: a reaction temperature of 0-200℃ and a reaction time of 0.1-24h.

10. The lubricating oil composition according to claim 5, characterized in that, The molar ratio of the acidic phosphate ester to the nitrogen-containing organic matter is 1:0.4-5; the reaction conditions for the phosphate ester salt include: a reaction temperature of 20-150℃ and a reaction time of 0.5-12h.

11. The lubricating oil composition according to claim 5, characterized in that, The molar ratio of the acidic phosphate ester to the nitrogen-containing organic matter is 1:0.5-2; the reaction conditions for the phosphate ester salt include: a reaction temperature of 60-120℃ and a reaction time of 1-5h.

12. The lubricating oil composition according to any one of claims 1-11, characterized in that, The ashless dispersant is selected from polyisobutylene succinimide and / or boronized polyisobutylene succinimide; the viscosity index improver is selected from polymethacrylate and / or polyisobutylene; the antioxidant is selected from one or more of alkylated diphenylamine, N-phenyl-α-naphthylamine, shielding phenol and phenolic esters; the metal deactivator is selected from one or more of alkylaminomethylenetriazole, benzotriazole dialkylamine formaldehyde condensate, thiadiazole polysulfide and thiadiazole alkyl mercaptan hydrogen peroxide condensate; the base oil is selected from one or more of API Group I, II, III, IV and V base oils.

13. A method for preparing the electric vehicle transmission lubricating oil composition according to any one of claims 1 to 12, comprising the step of mixing various additives and base oils therein.

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