Lubricating oil composition and application thereof

Abstract

The invention discloses a lubricating oil composition and its application. In the present invention, the lubricating oil composition includes a composite antioxidant, a dispersant, an anti-wear agent, an acrylate anti-foaming agent, a manual transmission oil composite agent meeting the requirements of API MT-1, a residual base oil and a viscosity index improver; wherein the composite antioxidant is a mixture of sulfide octyl-N-phenyl-α-naphthylamine, thio-organic amine, 4-methylene-(4-diphenylamine)-2,6-di-tert-butylphenol; the anti-wear agent includes sulfide dibutylene carboxylic acid octyl ester and 2,5-dimercapto-1,3,4-thiadiazolidinyl carboxylate, and also includes butyl hexyl phosphate dodecanumium salt or dibutyl phosphate octadecylamine salt. The lubricating oil composition has good thermal oxidation stability and rubber compatibility, especially excellent anti-pitting performance, can effectively reduce the gear and bearing damage caused by fatigue wear of the vehicle under long-term alternating stress load, and provides long-term protection for the input shaft, intermediate shaft, output shaft and gear set of the manual transmission.

Description

Technical Field

[0001] The present invention belongs to a lubricating oil composition in the technical field of lubricating oils and lubricating oil additives, and particularly relates to a lubricating oil composition for a manual transmission and its application. Background Art

[0002] Due to characteristics such as high mechanical reliability, simple structure, and good power performance, MT manual transmissions account for 90% of the market share of reduction gearboxes for domestic heavy commercial vehicles. Approximately 57% of commercial vehicle transmissions are manual transmissions. In fact, long life has become a key technology and an important manifestation of the development trend of high-performance transmissions. Against this background, new requirements such as durability are also put forward for the lubricating oil used in them.

[0003] A manual transmission mainly consists of gears and shafts, and generates speed change and torque conversion through different gear combinations. To ensure that the gear structure is not worn during the meshing process and the torque transmission is stable during the gear synchronization process, the oil product needs to have excellent antioxidant performance and wear resistance. Especially for heavy-duty transmission gears, under long-term operating conditions, pitting, as a fatigue form related to lubrication, is one of the main failure forms of gears. With the development of commercial vehicle technology, the lubrication conditions of its transmission parts are more demanding than in the past. For example, the aerodynamic design of the whole vehicle reduces the air flow velocity around the rear axle and the transmission, which can effectively improve fuel efficiency, but at the same time increases the working temperature of the heavy-duty truck transmission by 25 - 30 °C, posing higher requirements for the lubricating oil in terms of antioxidant performance, pitting resistance performance, and rubber compatibility. If the lubricating oil cannot meet the working conditions requirements, there will be adverse consequences such as damage to the vehicle transmission and oil leakage from the transmission oil seal.

[0004] CN116925832A discloses a manual transmission oil additive composition and its application. The oil product blended with additives such as cyclohexanecarboxylic acid alkyl ester polysulfide and high-molecular succinimide with an aromatic amine group has good synchronizer durability, thermal oxidation stability, corrosion resistance performance, and friction characteristics, but does not mention the oil change cycle of the oil product. CN 1961063 B reports a lubricating oil composition for a manual transmission, which uses zinc dialkyldithiophosphate, magnesium sulfonate, alkyl phosphite, etc., and has excellent gear fork anti-annealing performance and speed change performance, without mentioning the thermal oxidation stability and pitting resistance performance of the oil product. CN112080333 A discloses a long-life manual transmission oil composition. The oil product blended with molybdenum dialkyldithiophosphorodithioate, type III hydrotreated base oil, polyalphaolefin synthetic base oil, etc. has an oil change cycle of up to 5 million kilometers, but does not mention the pitting resistance performance and rubber compatibility of the oil product. Summary of the Invention

[0005] To solve the problems and meet the requirements in the background art, the present invention has systematically studied the base oil, additives and their interaction relationships in the lubricating oil composition, and focused on the thermal oxidation stability, pitting resistance and rubber compatibility of the composition. The present invention provides a lubricating oil composition with good thermal oxidation stability and rubber compatibility, especially excellent pitting resistance, which can provide effective lubrication and long-term protection for the input shaft, intermediate shaft, output shaft and gear set of a manual transmission. The composition of the present invention has a relatively low cost and is particularly suitable for lubricating the manual transmission (MT) or the automated manual transmission (AMT) of heavy-duty trucks. The oil change interval of the lubricating oil can reach 600,000 kilometers. With the rapid development of the commercial vehicle industry, there is a huge demand for corresponding transmission oils, and it has broad prospects for popularization and application.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] I. A lubricating oil composition

[0008] Based on 100 parts by weight, the lubricating oil composition comprises the following components in parts by weight:

[0009] 0.2 - 2.0 parts of a compound antioxidant, 2.0 - 4.5 parts of a dispersant, 0.2 - 2.5 parts of an anti-wear agent, 0.001 - 0.02 parts of an acrylate anti-foaming agent, 1.5 - 5.0 parts of a compound agent for manual transmission oil meeting the API MT-1 requirement, and the balance being base oil and viscosity index improver;

[0010] The compound antioxidant is a mixture of sulfurized octyl-N-phenyl-α-naphthylamine, thio-organic amine, and 4-methylidene-(4-diphenylamine)-2,6-di-tert-butylphenol;

[0011] The anti-wear agent includes octyl sulfidized dibutenoate and 2,5-dimercapto-1,3,4-thiadiazole alkyl carboxylate, and the anti-wear agent also includes dodecyl ammonium butylhexyl phosphate or octadecylamine dibutyl phosphate.

[0012] Further, based on 100 parts by weight, the lubricating oil composition comprises the following components in parts by weight:

[0013] 0.32 - 1.5 parts of a compound antioxidant, 2.0 - 4.0 parts of a dispersant, 0.65 - 2.5 parts of an anti-wear agent, 0.001 - 0.01 parts of an acrylate anti-foaming agent, 1.5 - 4.55 parts of a compound agent for manual transmission oil meeting the API MT-1 requirement, and the balance being base oil and viscosity index improver.

[0014] In the compound antioxidant, the mass ratio of sulfurized octyl-N-phenyl-α-naphthylamine to 4-methylidene-(4-diphenylamine)-2,6-di-tert-butylphenol is (0.1~0.2):0.5, and the mass of the thio-organic amine accounts for 0.2~0.4% of the total mass of the lubricating oil composition.

[0015] Further, the thio-organic amine is preferably dioctylamine disulfide.

[0016] In the anti-wear agent, the mass of sulfurized octyl butenedioate accounts for 0.1~0.5% of the total mass of the lubricating oil composition; the mass ratio of 2,5-dimercapto-1,3,4-thiadiazole alkyl carboxylate to dodecyl ammonium butylhexyl phosphate or octadecylamine dibutyl phosphate is (0.5~1):1.

[0017] Further, the sulfurized octyl butenedioate is preferably dioctyl butenedioate disulfide.

[0018] Further, the 2,5-dimercapto-1,3,4-thiadiazole alkyl carboxylate is preferably 2,5-dimercapto-1,3,4-thiadiazole 2-ethylhexanoate.

[0019] The dispersant is bis / polyisobutylene succinimide.

[0020] In the compound additive for manual transmission oil meeting the API MT-1 requirements, the sulfur content in the compound additive for manual transmission oil is not less than 0.1 wt%, the phosphorus content in the compound additive for manual transmission oil is not less than 0.05 wt%, and the nitrogen content in the compound additive for manual transmission oil is not less than 0.03 wt%.

[0021] The base oil is a mixture of poly-α-olefin (PAO) with a kinematic viscosity at 100 °C of 4~10 mm 2 / s, alkylnaphthalene AN base oil and API Group II 150BS mineral base oil, wherein the mass of the alkylnaphthalene AN base oil is 10% of the total mass of the lubricating oil composition;

[0022] The viscosity index improver is a PMA viscosity index improver.

[0023] Under the test conditions of 300 hours for the L-60-1 oxidation stability of the lubricating oil composition, the viscosity of the composition at 100 °C increases by less than 30%, the sludge score is greater than 9.5, and the varnish score is greater than 9.4.

[0024] The test time of the FZG pitting test of the lubricating oil composition reaches at least 450 hours.

[0025] The test time of the FE-8 pitting test (300 rpm, 80 kN, 100 °C) of the lubricating oil composition can even reach 750 hours.

[0026] II. Application of a Lubricating Oil Composition

[0027] The described lubricating oil composition is suitable for lubricating heavy-duty truck manual transmissions (MT) or automated manual transmissions (AMT).

[0028] Furthermore, the oil change interval of the described lubricating oil composition can reach 600,000 kilometers.

[0029] Compared with the prior art, the described lubricating oil composition proposed by the present invention has the following beneficial effects:

[0030] 1) The present invention uses a compound of sulfurized octyl-N-phenyl-α-naphthylamine, thio-organic amine, and 4-methylidene-(4-diphenylamine)-2,6-di-tert-butylphenol. Under long-term conditions, it can effectively inhibit the increase in oil viscosity and the formation of paint films, and effectively improve the thermal oxidation stability of the oil.

[0031] 2) The anti-wear agent in the present invention includes octyl 2,5-dimercapto-1,3,4-thiadiazole carboxylate, and also includes at least one of dodecyl ammonium butylhexyl phosphate and octadecylamine dibutyl phosphate. This combination of anti-wear agents can significantly improve the pitting resistance of the oil while maintaining good load-carrying capacity of the oil, and can effectively reduce the damage of gears and bearings caused by fatigue wear under long-term alternating stress loads of vehicles, providing long-term protection for the input shaft, intermediate shaft, output shaft, and gear set of the manual transmission.

[0032] 3) The base oil system used in the present invention is compounded with different additives to ensure good rubber compatibility of the oil, which can effectively extend the oil change interval of the oil. It is particularly suitable for heavy-duty truck manual transmissions (MT) or automated manual transmissions (AMT), and the oil change interval of the lubricating oil can reach 600,000 kilometers. Specific Embodiments

[0033] The following provides a detailed description of the embodiments of the present invention. These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and processes are given. However, the protection scope of the present invention is not limited to the following embodiments. For the experimental methods without specific conditions noted in the following embodiments, they are generally carried out under conventional conditions.

[0034] In the following examples, sulfurized octyl-N-phenyl-α-naphthylamine is from V407 of Vanderbilt, 4-methylenebis(2,6-di-tert-butylphenol) is from Ethanox 4799 produced by SI Company, bis / polyisobutenyl succinimide is from RHY158 of PetroChina Lubricant Company, 2-ethylhexyl 2,5-dimercapto-1,3,4-thiadiazole is from V871 of Vanderbilt, acrylate-type antifoaming agent is from H2030 produced by Afton Chemical Corporation or PC1344 produced by Allnex Zhenxin Company, and the API MT-1 required manual transmission oil compound is H349 compound produced by Afton Chemical Corporation or V4164 compound produced by PetroChina Lubricant Company. API Group I HVIS150BS base oil, alkylnaphthalene base oils AN5 and AN10 are from ExxonMobil, and PAO4, PAO6, PAO8, and PAO10 base oils are from PetroChina Lubricant Company. The PMA viscosity index improver is V0-120 produced by Evonik Industries AG.

[0035] For the FZG gear pitting, a C / PT type gear is used as the test piece, which is mainly used to evaluate the destructive damage of the gear starting from the tooth root due to fatigue wear under the long-term alternating stress load on the gear surface by the gear oil. The FE8 bearing test mainly evaluates the working ability of the lubricating oil to protect the bearing life on the bearing surface.

[0036] Example 1

[0037] A lubricating oil composition (I) comprises: 0.2 wt% of sulfurized octyl-N-phenyl-α-naphthylamine, 0.3 wt% of dithiocaprylamine, 1.0 wt% of 4-methylenebis(2,6-di-tert-butylphenol) (compound antioxidant), 2.0 wt% of bis / polyisobutenyl succinimide (dispersant), 0.5 wt% of octyl dithiodibutenoate, 1.0% of 2-ethylhexyl 2,5-dimercapto-1,3,4-thiadiazole, 1.0 wt% of dodecylammonium butylhexyl phosphate (antiwear agent), 0.01 wt% of antifoaming agent (acrylate-type antifoaming agent), 1.5 wt% of the API MT-1 required manual transmission oil compound, 74.99 wt% of PAO10, 5.0 wt% of HVIS150BS, 10.0 wt% of alkylnaphthalene base oil AN5, and 2.5 wt% of PMA viscosity index improver. The sum of the above components is 100 wt%.

[0038] Comparative Example 1: Except that the composite antioxidant is replaced by 1.5 wt% of sulfonated octyl-N-phenyl-α-naphthylamine, the rest is the same as composition (I). Comparative Example 2: Except that the composite antioxidant is replaced by 1.5 wt% of 4-methylene-(4-diphenylamine)-2,6-di-tert-butylphenol, the rest is the same as composition (I). Comparative Example 3: Except that the composite antioxidant is replaced by 0.5 wt% of sulfonated octyl-N-phenyl-α-naphthylamine and 1.0 wt% of 4-methylene-(4-diphenylamine)-2,6-di-tert-butylphenol, the rest is the same as composition (I).

[0039] Table 1 is the test results of Example 1 and Comparative Examples 1, 2 and 3.

[0040]

[0041] The results in Table 1 show that (1) Compared with Comparative Examples 1, 2, and 3, Composition I exhibits excellent antioxidant properties, indicating that the use of a certain proportion of octyl-N-phenyl-α-naphthylamine sulfide, thio-organic amine, and 4-methylene-(4-diphenylamine)-2,6-di-tert-butylphenol mixed has a good synergistic effect, can effectively inhibit the viscosity growth of oil products and the formation of paint films under long-term conditions, and also has good copper corrosion resistance and wear resistance. (2) Compared with Comparative Examples 1 and 2, the use of octyl-N-phenyl-α-naphthylamine sulfide or 4-methylene-(4-diphenylamine)-2,6-di-tert-butylphenol alone in Composition I will not be conducive to controlling the viscosity growth of oil products. (3) Compared with Comparative Example 3, the use of disulfide n-octylamine in Composition I is conducive to improving the anti-wear performance of oil products.

[0042] Example 2

[0043] A lubricating oil composition (II) includes: 0.034 wt% of octyl-N-phenyl-α-naphthylamine sulfide, 0.2 wt% of n-octyl disulfide, 0.086 wt% of 4-methylene-(4-diphenylamine)-2,6-di-tert-butylphenol (composite antioxidant), 4.0 wt% of bis / polyisobutylene succinimide (dispersant), 0.1 wt% of octyl disulfide butene carboxylate, 0.5% of 2,5-dimercapto-1,3,4-thiadiazole 2-ethylhexanoate, 1.0 wt% of dibutyl phosphate octadecylamine salt (antiwear agent), 0.001 wt% of antifoaming agent (acrylate type antifoaming agent), 2.85 wt% of API-compliant Manual transmission oil compound required by MT-1, 75.729wt% PAO8, 2.0wt% HVIS150BS, 10.0wt% alkyl naphthalene base oil AN12, 3.5wt% PMA viscosity index improver. The sum of the above components is 100wt%.

[0044] Comparative Example 4: Except that the anti-wear agent was replaced by 1.6 wt% of octyl dithiobutenoate, the rest was the same as Composition (II). Comparative Example 5: Except that the anti-wear agent was replaced by 0.1 wt% of octyl dithiobutenoate and 1.5% of 2-ethylhexyl 2,5-dimercapto-1,3,4-thiadiazole, the rest was the same as Composition (II).

[0045] Table 2 shows the test results of Example 2, Comparative Example 4, and Comparative Example 5

[0046]

[0047] The results in Table 2 show that compared with Comparative Example 4 and Comparative Example 5, Composition (II) exhibits excellent pitting resistance and load-carrying capacity, indicating that the compounding of octyl dithiobutenoate, alkyl carboxylate of 2,5-dimercapto-1,3,4-thiadiazole, and octadecylamine salt of dibutyl phosphate can significantly improve the FZG pitting resistance and FE-8 pitting resistance of the oil while maintaining good load-carrying capacity of the composition. Under the condition of long-term alternating stress load, it can well protect the gear set and bearings inside the vehicle gearbox, and the above single-component anti-wear agents used alone cannot achieve this effect.

[0048] Example 3

[0049] A lubricating oil composition (III) comprises: 0.1 wt% of sulfurized octyl-N-phenyl-α-naphthylamine, 0.4 wt% of dithiooctylamine, 0.4 wt% of 4-methylidene-(4-diphenylamine)-2,6-di-tert-butylphenol (compound antioxidant), 3.0 wt% of bis / polyisobutylene succinimide (dispersant), 0.3 wt% of octyl dithiobutenoate, 0.6% of 2-ethylhexyl 2,5-dimercapto-1,3,4-thiadiazole, 0.6 wt% of octadecylamine salt of dibutyl phosphate (anti-wear agent), 0.005 wt% of anti-foaming agent (acrylate type anti-foaming agent), 4.55 wt% of a manual transmission oil compound meeting API MT-1 requirements, 64.545 wt% of PAO4, 7.0 wt% of HVIS150BS, 10.0 wt% of alkylnaphthalene base oil AN5, and 8.5 wt% of PMA viscosity index improver. The sum of the above components is 100 wt%.

[0050] Comparative Example 6: Except that 64.545 wt% of PAO4, 7.0 wt% of HVIS150BS, 10.0 wt% of alkyl naphthalene base oil AN5, and 8.5 wt% of PMA viscosity index improver were replaced by 69.545 wt% of PAO4, 7.0 wt% of HVIS150BS, 5.0 wt% of alkyl naphthalene base oil AN5, and 8.5 wt% of PMA viscosity index improver, the rest was the same as Composition (III). Comparative Example 7: Except that 64.545 wt% of PAO4, 7.0 wt% of HVIS150BS, 10.0 wt% of alkyl naphthalene base oil AN5, and 8.5 wt% of PMA viscosity index improver were replaced by 74.545 wt% of PAO4, 7.0 wt% of HVIS150BS, and 8.5 wt% of PMA viscosity index improver, the rest was the same as Composition (III). Comparative Example 8: Except that 64.545 wt% of PAO4, 7.0 wt% of HVIS150BS, 10.0 wt% of alkyl naphthalene base oil AN5, and 8.5 wt% of PMA viscosity index improver were replaced by 59.545 wt% of PAO4, 7.0 wt% of HVIS150BS, 15.0 wt% of alkyl naphthalene base oil AN5, and 8.5 wt% of PMA viscosity index improver, the rest was the same as Composition (III).

[0051] Table 3 shows the test results of Example 3 and Comparative Examples 6 and 7

[0052]

[0053] As can be seen from Table 3, the base oil system used in Composition (III) is compounded with different additives, ensuring that the oil product has good rubber compatibility and anti-foam performance, and can effectively extend the oil change cycle of the oil product. If the alkyl naphthalene base oil is not added or the addition amount is less than 10%, the anti-foam performance of the oil product is poor, and the rubber compatibility test of the oil product cannot be passed, resulting in oil leakage during actual use and shortening the oil change cycle of the oil product.

[0054] Example 4

[0055] A lubricating oil composition (IV) comprises: 0.15 wt% of sulfurized octyl-N-phenyl-α-naphthylamine, 0.2 wt% of dithiocaprylamine, 0.5 wt% of 4-methylidene-(4-diphenylamine)-2,6-di-tert-butylphenol (compound antioxidant), 2.4 wt% of bis / polyisobutylene succinimide (dispersant), 0.2 wt% of octyl dithiobutenoate, 0.5% of 2-ethylhexyl 2,5-dimercapto-1,3,4-thiadiazole, 1.0 wt% of dodecyl ammonium butylhexyl phosphate (antiwear agent), 0.01 wt% of antifoaming agent (acrylate-type antifoaming agent), 2.55 wt% of a manual transmission oil compound meeting API MT-1 requirements, 71.99 wt% of PAO6, 5.0 wt% of HVIS150BS, 10.0 wt% of alkylnaphthalene base oil AN5, and 5.5 wt% of PMA viscosity index improver. The sum of the above components is 100 wt%.

[0056] Table 4 shows the evaluation results of the composition (IV) of Example 4

[0057]

[0058] The results show that for the L-60-1 oxidation stability of the lubricating oil composition (IV) under the test conditions of 300 hours, the viscosity of the composition at 100 °C increases by 10.71%, the sludge score is greater than 9.8, and the varnish score is 9.6. The test time of its FE-8 pitting test (300 rpm, 80 kN, 100 °C) can reach 755 hours, and the FE-8 pitting test time reaches 478 hours. It has passed the compatibility test with three sealing materials. It shows that the above lubricating oil composition has good thermal oxidation stability and rubber compatibility, especially excellent pitting resistance, and can effectively reduce the damage of gears and bearings caused by fatigue wear under long-term alternating stress loads of vehicles, and can provide long-term protection for the input shaft, intermediate shaft, output shaft and gear set of the manual transmission. The composition of the present invention is particularly suitable for lubricating the manual transmission of heavy-duty trucks, and the oil change period of the lubricating oil can reach 600,000 kilometers.

[0059] Certainly, the present invention can also have many other embodiments. Those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations should all fall within the protection scope of the claims of the present invention.

Claims

1. A lubricating oil composition, characterized in that: The lubricating oil composition comprises the following components in parts by weight based on 100 parts by weight: 0.2-2.0 parts of composite antioxidant, 2.0-4.5 parts of dispersant, 0.2-2.5 parts of anti-wear agent, 0.001-0.02 parts of acrylate anti-foaming agent, 1.5-5.0 parts of manual transmission oil compound that meets API MT-1 requirements, and the balance is base oil and viscosity index improver; The composite antioxidant is a mixture of octyl sulfide-N-phenyl-α-naphthylamine, thio-organic amine, and 4-methylene-(4-diphenylamine)-2,6-di-tert-butylphenol; The anti-wear agent includes sulphurized dibutylene carboxylate octyl ester and 2,5-dimercapto-1,3,4-thiadiazolidinyl carboxylate, and the anti-wear agent also includes butyl hexyl phosphate lauryl ammonium salt or dibutyl phosphate octadecylamine salt; In the composite antioxidant, the mass ratio of octyl sulfide-N-phenyl-α-naphthylamine to 4-methylene-(4-diphenylamine)-2,6-di-tert-butylphenol is (0.1-0.2):0.5, and the mass of the thio-organic amine accounts for 0.2-0.4% of the total mass of the lubricating oil composition; In the anti-wear agent, the mass of sulphurized dibutylene carboxylate accounts for 0.1-0.5% of the total mass of the lubricating oil composition; the mass ratio of 2,5-dimercapto-1,3,4-thiadiazolidinyl carboxylate to butyl hexyl phosphate dodecanedammonium salt or dibutyl phosphate octadecylamine salt is (0.5-1):1; The base oil has a kinematic viscosity of 4 to 10 mm at 100°C. 2 / s a mixture of polyalphaolefin, alkylnaphthalene AN base oil and API I Group 150BS mineral base oil, wherein the mass of the alkylnaphthalene AN base oil is 10% of the total mass of the lubricating oil composition; The viscosity index improver is a PMA viscosity index improver; The L-60-1 oxidation stability of the lubricating oil composition is tested for 300 hours, and the viscosity of the composition at 100° C. increases by less than 30%, the sludge score is greater than 9.5, and the varnish score is greater than 9.

4.

2. A lubricating oil composition according to claim 1, characterized in that: The lubricating oil composition comprises the following components in parts by weight based on 100 parts by weight: 0.32-1.5 parts of composite antioxidant, 2.0-4.0 parts of dispersant, 0.65-2.5 parts of anti-wear agent, 0.001-0.01 parts of acrylate anti-foaming agent, 1.5-4.55 parts of manual transmission oil compound that meets the requirements of API MT-1, and the balance is base oil and viscosity index improver.

3. The lubricating oil composition according to claim 1 or 2, characterized in that: The dispersant is bis / polyisobutylene succinimide.

4. The lubricating oil composition according to claim 1 or 2, characterized in that: In the manual transmission oil compound that meets the API MT-1 requirements, the sulfur content is not less than 0.1wt% in the manual transmission oil compound, the phosphorus content is not less than 0.05wt% in the manual transmission oil compound, and the nitrogen content is not less than 0.03wt% in the manual transmission oil compound.

5. The lubricating oil composition according to claim 1, characterized in that: The test time of the lubricating oil composition in the FE-8 pitting test is at least 750 hours, and the test time of the FZG pitting test is at least 450 hours.

6. The use of the lubricating oil composition according to claim 1, characterized in that: The lubricating oil composition is suitable for lubricating a manual transmission or an automatic manual transmission of a heavy-duty truck.

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