Gearbox lubricating oil composition

Abstract

The invention discloses a gearbox lubricating oil composition. The gearbox lubricating oil composition comprises base oil and additives, wherein the additives comprise at least one ester polysulfide, at least one succinimide dispersant, at least one calcium-containing metal detergent and at least one high-alkalinity zinc dialkyl dithiophosphate. The lubricating oil composition provided by the invention can effectively improve the wear resistance of gearbox lubricating oil, and also can significantly reduce the traction coefficient of an oil product.

Description

Technical Field

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

[0002] In modern vehicle transmissions, in addition to using multi-plate friction clutches in the clutch and brake units, conical friction synchronizers are also widely used in the transmission system. The synchronizer has become an important component of the transmission. Its function is to make the gears with different rotational speeds mesh with each other after reaching "synchronization" through a friction contact process between the synchronizing ring and the cone during gear shifting, avoiding the impact between gears during the shifting process and achieving smooth shifting operation. The performance of the synchronizer depends not only on the strength, hardness, and anti-wear ability of the synchronizing ring and the cone themselves, but also on the transmission oil used, which will directly affect the smoothness of the shifting operation and the service life of the synchronizer. For transmission lubricating oils, on the one hand, it is required to have good anti-wear performance to reduce the wear of the synchronizing ring and ensure that the synchronizer can work continuously throughout its service life. On the other hand, with the rapid development of the automotive industry, energy conservation and consumption reduction have attracted more and more attention. Transmission lubricating oils are also required to have a low traction coefficient, thereby reducing the operating resistance of the friction components of the transmission, improving the energy transfer efficiency of the transmission, and improving the fuel economy of the oil.

[0003] Patent CN1961063A discloses a lubricating oil composition for a manual transmission, using a formulation system such as magnesium sulfonate, zinc dialkyldithiophosphate, sulfur-containing extreme pressure additive, and alkyl phosphite, which can simultaneously meet the anti-retreat annealing performance of gear forks and the shifting performance. Since the kinematic viscosity of the oil at 40 °C is relatively low, at 25 - 30 mm 2 / s, it can also achieve fuel savings for vehicles, but does not mention the anti-wear performance of the oil. Patent CN111909758A discloses a transmission oil composition for improving wear protection, using a mixture of phosphite and phosphate ester, thioester compound, zinc dialkyldithiophosphate compound, molybdenum-containing compound, etc., which can be used to control and reduce the wear of manual transmission oil, but does not mention the traction coefficient and fuel economy of the oil.

[0004] The traction coefficient of the lubricating oil is directly related to the energy transfer efficiency of the transmission components. A lower traction coefficient can improve the energy transfer efficiency of the transmission components and improve the fuel economy of the oil. Currently, there is no relevant report on the research of transmission lubricating oils with a low traction coefficient. Summary of the Invention

[0005] To solve the problems and meet the requirements in the background art, the present invention provides a gearbox lubricating oil composition. The lubricating oil composition contains a certain amount of base oil and additives. The additives include esters polysulfides with specific contents and specific structures, specific succinimide dispersants, specific metal detergents, and specific zinc dialkyldithiophosphates, etc. The lubricating oil composition has good anti-wear performance and a low traction coefficient, can improve the transmission efficiency of the gearbox, has good fuel economy, and is suitable for lubricating vehicle gearboxes or industrial gearboxes.

[0006] The technical solution of the present invention is as follows:

[0007] The gearbox lubricating oil composition proposed by the present invention contains a base oil and additives, and the additives contain the following components:

[0008] (A) At least one esters polysulfide;

[0009] (B) At least one succinimide dispersant;

[0010] (C) At least one calcium-containing metal detergent;

[0011] (D) At least one overbased zinc dialkyldithiophosphate anti-wear agent;

[0012] The structural formula of the esters polysulfide is as follows:

[0013]

[0014] Wherein, n is 1 to 4; R1 and R2 may be the same or different, and are alkyl groups having 12 to 18 carbon atoms;

[0015] The structural formula of the succinimide dispersant is as follows:

[0016]

[0017] Wherein, PIB is polyisobutene, with a molecular weight of 2500 to 4000; n is a positive integer not equal to zero, and R3 is a hydroxyl group or an aromatic group.

[0018] The calcium-containing metal detergent includes one or more of calcium alkylbenzene sulfonate with a base number of 400 - 500 mg KOH / g, calcium alkyl salicylate with a base number of 200 - 350 mg KOH / g, and calcium sulfonated alkylphenol with a base number of 200 - 350 mg KOH / g.

[0019] In the lubricating oil composition, based on 100 parts by weight, the content of the ester polysulfide is 0.55 to 1.0 part, the content of the succinimide dispersant is 0.5 to 5.0 parts, the content of the calcium metal detergent is 0.95 to 2.4 parts, and the content of the overbased zinc dialkyldithiophosphate is 0.4 to 1.0 part.

[0020] The additives of the lubricating oil composition further include the following components:

[0021] (E) a phosphite phosphorus-containing antiwear agent;

[0022] (F) an antioxidant.

[0023] In the lubricating oil composition, based on 100 parts by weight, the content of the phosphite phosphorus-containing antiwear agent is 0.1 - 0.8 part, and the content of the antioxidant is 0.2 - 0.4 part.

[0024] The overbased zinc dialkyldithiophosphate includes one or more of zinc diisooctyldithiophosphate, zinc didecyldithiophosphate, and zinc isopropylisooctyldithiophosphate with a base number greater than 21 mg KOH / g.

[0025] The phosphite phosphorus-containing antiwear agent includes monoalkyl phosphite, preferably tetradecyl phosphite, hexadecyl phosphite, octadecyl phosphite, and eicosyl phosphite, where the alkyl can be straight-chain or branched-chain.

[0026] The antioxidant is a mixture of sulfurized octyl-N-phenyl-α-naphthylamine and thio-organic amine.

[0027] In the ASTM D4172 four-ball wear test of the transmission lubricating oil composition, the average wear scar diameter after 1 hour of testing is 0.25 mm or less, and the average wear scar diameter after 2 hours of testing is 0.30 mm or less.

[0028] In the friction and wear test on an ASTM D6452 SRV testing machine, the average wear scar diameter of the transmission lubricating oil composition after 2 hours of testing is 0.40 mm or less.

[0029] The above transmission lubricating oil composition is characterized in that in the ASTM D4172 four-ball wear test, the average wear scar diameter of the above lubricating oil composition after 1 hour of testing is 0.25 mm or less, and the average wear scar diameter after 2 hours of testing is 0.30 mm or less. In the friction and wear test on an ASTM D6452 SRV testing machine, the average wear scar diameter of the above lubricating oil composition after 2 hours of testing is 0.40 mm or less.

[0030] When the transmission lubricating oil composition is tested by MTM, a load of 1.0 GPa is applied between the friction material disc and the steel disc, and a sliding-rolling ratio (SRR) of 30% is maintained. At 40 °C and 60 °C, the traction coefficient of the oil can be reduced by more than 30%.

[0031] The lubricating oil composition can effectively improve the anti-wear performance of the transmission lubricating oil and has a low traction coefficient.

[0032] Compared with the prior art, the lubricating oil composition of the present invention has the following beneficial effects:

[0033] 1) The present invention uses a compound additive package formed by compounding a certain proportion of ester polysulfides, zinc dialkyldithiophosphate with high base number, etc. The additive package and the base oil form a transmission lubricating oil composition, and this lubricating oil composition can significantly improve the anti-wear performance of the oil;

[0034] 2) The transmission lubricating oil composition composed of an additive formula such as ester polysulfides, succinimide dispersant, calcium-containing metal detergent, zinc dialkyldithiophosphate with high base number and the base oil can effectively reduce the traction coefficient of the oil by effectively exerting the synergistic effect of each component, thereby improving the energy transfer efficiency of transmission components and the fuel economy of the oil. Detailed Description of the Invention

[0035] The following is 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 usually carried out under conventional conditions.

[0036] Four-ball machine test: The average wear scar diameter of the oil is measured according to ASTM D4172 "Test Method for Wear Resistance of Lubricating Oils (Four-Ball Machine Method)". The test conditions are: load 392 N, time 1 h or 2 h, temperature 75 °C, speed 1200 r / min. SRV friction and wear test: The wear scar diameter of the oil is measured according to ASTM D6452 "SRV Test Method for Friction and Wear of Extreme Pressure Lubricating Oils". The test conditions are: load 200 N, frequency 50 HZ, time 2 h, temperature 80 °C, stroke 1 mm. MTM traction machine test: At the contact point, the sliding-rolling ratio (SRR) of 30% is maintained by adjusting the surface speeds of the ball and the disc, a pressure of 1.0 GPa is applied between the friction material disc and the steel disc, and the traction coefficient of the oil is measured at 40 °C and 60 °C.

[0037] In the following examples and comparative examples, typical ester polysulfides are derived from the sulfur-containing agents L03 and L04 produced by Lubrizol. The succinimide dispersant can be prepared by the method of Patent CN1169464A. The overbased zinc dialkyldithiophosphate can be prepared by the method of Patent CN118994233A. The calcium-containing metal detergent is the calcium alkylbenzene sulfonate additive RHY107R or the calcium salicylate additive RHY109 of PetroChina Lubricant Company or the calcium sulfonated alkylphenol OLOA219 produced by Chevron. The antioxidant is V407 produced by Vanderbilt Company of the United States. The phosphite-containing phosphorus antiwear agent is derived from LP2704 or ZR87 additive of PetroChina Lubricant Company. The API Group I HVIH2, HVIP6 base oils, API Group III VHVI4, VHVI6, VHVI8 base oils, and API Group IV PAO2, PAO4, PAO10 base oils are from PetroChina Lubricant Company. The base oil contains one or more combinations of API Group I, II, III, and IV groups. The kinematic viscosity of the combined base oil at 100 °C is approximately 4 cSt - 12 cSt.

[0038] Example 1

[0039] A transmission lubricating oil composition (I) comprises: 0.55 wt% of an ester polysulfide (Component A, n is 3, and both R1 and R2 are straight-chain alkyl groups of C18), 2.0 wt% of succinimide (Component B, R3 is a hydroxyl group), 0.95 wt% of calcium alkylbenzene sulfonate (Component C), 0.8 wt% of zinc diisooctyldithiophosphate with a base number greater than 21 mg KOH / g (Component D), 0.4 wt% of an antioxidant (Component E), 0.4 wt% of octadecyl phosphite (Component F), and the balance is a base oil with a kinematic viscosity of approximately 5 cSt at 100 °C. The sum of the above components is 100 wt%.

[0040] Comparative Example 1: Without Component (A), Component (C) is replaced by 1.30 wt% of calcium alkylbenzene sulfonate, and Component (D) is replaced by 1.0 wt% of zinc diisooctyldithiophosphate with a base number greater than 21 mg KOH / g, and the rest is the same as Composition (I).

[0041] Comparative Example 2: Without Component (D), Component (A) is replaced by 1.0 wt% of an ester polysulfide, and Component (F) is replaced by 0.75 wt% of octadecyl phosphite (Component F), and the rest is the same as Composition (I).

[0042] Comparative Example 3: Without Components (A), (B), (C), (D), (E), and (F), 5.1 wt% of the commercially available Afton gear oil compound Hitec 355 is used, and the base oil is the same as Composition (I).

[0043] Table 1 shows the test results of Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3.

[0044]

[0045] The following points can be obtained from the test results in Table 1:

[0046] (1) Compared with Comparative Examples 1 and 2, Composition I exhibits excellent anti-wear performance and a lower traction coefficient, indicating that the use of additives such as ester polysulfides, succinimide dispersants, calcium-containing metal detergents, and overbased zinc dialkyldithiophosphates has good synergistic effects.

[0047] (2) Compared with Comparative Example 1, at the same phosphorus content in the composition, without using ester polysulfides, the anti-wear performance of the composition containing only succinimide dispersant, calcium-containing metal detergent, and overbased zinc dialkyldithiophosphate decreases to a certain extent, and the traction coefficients are relatively high.

[0048] (3) Compared with Comparative Example 2, without using zinc diisooctyldithiophosphate, the anti-wear performance of the composition decreases significantly, and the traction coefficient also increases significantly. This means that if overbased zinc dialkyldithiophosphate or ester polysulfides are not used, the synergistic effects of each additive are not obvious, affecting the overall performance of the oil product.

[0049] (4) Compared with Comparative Example 3, with the same additive dosage, Composition I can effectively reduce the traction coefficient. Compared with the commercial product, at 40 °C and 60 °C, the traction coefficients of MTM decrease by 35.8% and 36.1% respectively.

[0050] Example 2

[0051] A transmission lubricating oil composition (II) comprises: 1.0 wt% of an ester polysulfide (Component A, n = 2, R1 and R2 are straight-chain alkyl groups of C12), 5.0 wt% of succinimide (Component B, R3 is a hydroxyl group), 2.4 wt% of calcium salicylate (Component C), 0.4 wt% of zinc diisooctyldithiophosphate with a base number greater than 21 mg KOH / g (Component D), and the balance is a base oil with a kinematic viscosity of about 6 cSt at 100 °C. The sum of the above components is 100 wt%.

[0052] Comparative Example 4: Component (A) is replaced by 1.1 wt% of an ester polysulfide with the same structure, and Component (D) is replaced by 0.3 wt% of zinc didodecyldithiophosphate with a base number greater than 21 mg KOH / g, and the rest is the same as Composition (II).

[0053] Comparative Example 5: Component (B) was replaced by succinimide with the same structure at 5.1 wt%, and component (D) was replaced by zinc dialkyldithiophosphate with a base number greater than 21 mg KOH / g at 0.3 wt%. The rest was the same as Composition (II).

[0054] Comparative Example 6: Component (C) was replaced by calcium salicylate with the same structure at 2.5 wt%, and component (D) was replaced by zinc dialkyldithiophosphate with a base number greater than 21 mg KOH / g at 0.3 wt%. The rest was the same as Composition (II).

[0055] Comparative Example 7: Component (A) was replaced by ester polysulfide with the same structure at 0.9 wt%, and component (D) was replaced by zinc dialkyldithiophosphate with a base number greater than 21 mg KOH / g at 0.5 wt%. The rest was the same as Composition (II).

[0056] Comparative Example 8: Components (A), (B), (C), and (D) were not included, and 8.8 wt% of commercially available CNPC transmission oil compound RHY 4165B was used. The base oil was the same as Composition (II).

[0057] Table 2 shows the test results of Example 2 and Comparative Examples 4, 5, 6, 7, and 8

[0058]

[0059]

[0060] The following points can be obtained from the test results in Table 2:

[0061] (1) Although Example 2 does not contain phosphite phosphorus-containing antiwear agents and antioxidants, but contains at least four components mentioned in the present invention, the composition also exhibits certain antiwear performance and a low traction coefficient.

[0062] (2) Comparative Example 4 with a relatively large content of component (A), Comparative Example 5 with a relatively large content of component (B), and Comparative Example 6 with an excessive content of component (C) all have poor antiwear performance and a high traction coefficient. In Comparative Example 7, since it contains at least four components mentioned in the present invention and all are within the disclosed mass ranges, the composition exhibits acceptable antiwear performance and a low traction coefficient.

[0063] (3) Compared with Comparative Example 8, under the condition that the additive dosage remains unchanged, Composition II can effectively reduce the traction coefficient. Compared with the commercially available product, at 40 °C and 60 °C, the traction coefficients of MTM decreased by 30.6% and 31% respectively.

[0064] Example 3

[0065] A gearbox lubricating oil composition (III) comprises: 0.55 wt% of an ester polysulfide (component A, n is 4, R1 and R2 are straight-chain alkyl groups of C16), 0.5 wt% of succinimide ((component B, R3 is a hydroxyl group)), 0.95 wt% of calcium sulfonated alkylphenol (component C), 0.9 wt% of zinc isopropyl isooctyl dithiophosphate with a base number greater than 21 mg KOH / g (component D), and the balance is a base oil with a kinematic viscosity of about 12 cSt at 100 °C. The sum of the above components is 100 wt%.

[0066] Comparative Example 9: Component (A) was replaced by 0.50 wt% of an ester polysulfide with the same structure, and component (D) was replaced by 0.95 wt% of zinc didodecyl dithiophosphate with a base number greater than 21 mg KOH / g, and the rest was the same as composition (II).

[0067] Comparative Example 10: Component (B) was replaced by 0.45 wt% of succinimide with the same structure, and component (D) was replaced by 0.95 wt% of zinc didodecyl dithiophosphate with a base number greater than 21 mg KOH / g, and the rest was the same as composition (II).

[0068] Comparative Example 11: Component (C) was replaced by 0.90 wt% of calcium sulfonated alkylphenol with the same structure, and component (D) was replaced by 0.95 wt% of zinc didodecyl dithiophosphate with a base number greater than 21 mg KOH / g, and the rest was the same as composition (II).

[0069] Table 3 shows the test results of Example 3 and Comparative Examples 9, 10, and 11

[0070]

[0071] The following points can be obtained from the test results in Table 3:

[0072] (1) Although Example 3 does not contain a phosphite phosphorus-containing anti-wear agent and an antioxidant, it contains at least four components mentioned in the present invention, and the composition exhibits acceptable anti-wear performance and a low traction coefficient.

[0073] (2) There are obvious differences in anti-wear performance and traction coefficient between Comparative Example 9 with a lower content of component (A), Comparative Example 10 with a lower content of component (B), and Comparative Example 11 with an excessively low content of component (C) and the composition (III) of Example 3.

[0074] (3) The traction coefficient of composition (III) has decreased significantly compared with the comparative examples.

[0075] Example 4

[0076] A gearbox lubricating oil composition (IV) comprises: 0.85 wt% of an ester polysulfide (component A, n is 1, R1 and R2 are straight-chain alkyl groups with 14 carbon atoms), 3.15 wt% of succinimide (component B), 1.0 wt% of calcium alkylbenzene sulfonate (component C), 1.0 wt% of zinc diisooctyl dithiophosphate with a base number greater than 21 mg KOH / g (component D), 0.2 wt% of an antioxidant (component E), 0.8 wt% of eicosyl phosphite (component F), and the balance is a base oil with a kinematic viscosity of approximately 8 cSt at 100 °C. The sum of the above components is 100 wt%.

[0077] Comparative Example 12: A gearbox lubricating oil composition (V) comprises: 7.0 wt% of a commercially available Hitec 3080 gearbox oil compound from Afton Chemical Corporation, and the balance is a base oil with a kinematic viscosity of approximately 8 cSt at 100 °C. The sum of the above components is 100 wt%.

[0078] Table 4 shows the evaluation results of the composition (IV) of Example 4 and Comparative Example 12

[0079]

[0080] The results show that in the ASTM D4172 four-ball wear test, the average wear scar diameter of the lubricating oil composition (IV) is 0.22 mm after 1 hour of testing and 0.27 mm after 2 hours of testing. In the ASTM D6452 SRV tribometer friction and wear test, the average wear scar diameter is 0.31 mm after 2 hours of testing. In the MTM test, compared with commercially available products, the traction coefficient of the oil product of the composition decreases by more than 30%. It shows that the above lubricating oil composition can provide anti-wear protection for the gear set in a manual gearbox, and at the same time has a lower traction coefficient and good fuel economy. The composition can be applied to the lubrication of vehicle manual gearboxes.

[0081] Of course, 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 transmission lubricating oil composition, characterized in that, The transmission lubricating oil composition comprises a base oil and additives, and the additives comprise the following components: (A) At least one ester polysulfide; (B) At least one succinimide dispersant; (C) At least one calcium-containing metal detergent; (D) At least one overbased zinc dialkyldithiophosphate antiwear agent; The structural formula of the ester polysulfide is as follows: Wherein, n is 1 to 4; R1 and R2 are alkyl groups having 12 to 18 carbon atoms; The structural formula of the succinimide dispersant is as follows: Wherein, R3 is a hydroxyl group or an aromatic group.

2. The gearbox lubricating oil composition according to claim 1, characterized in that, The calcium-containing metal detergent comprises one or more of calcium alkylbenzenesulfonate with a base number of 400-500 mg KOH / g, calcium alkylsalicylate with a base number of 200-350 mg KOH / g, and calcium sulfonated alkylphenol with a base number of 200-350 mg KOH / g.

3. The transmission lubricating oil composition according to claim 1, characterized in that, Based on 100 parts by weight of the transmission lubricating oil composition, the content of the ester polysulfide is 0.55 to 1.0 part, the content of the succinimide dispersant is 0.5 to 5.0 parts, the content of the calcium-containing metal detergent is 0.95 to 2.4 parts, and the content of the overbased zinc dialkyldithiophosphate is 0.4 to 1.0 part.

4. A gearbox lubricating oil composition according to claim 1, characterized in that, The additives of the transmission lubricating oil composition further comprise the following components: (E) Phosphite phosphorus-containing antiwear agent; (F) Antioxidant.

5. A gearbox lubricating oil composition according to claim 4, characterized in that Based on 100 parts by weight of the transmission lubricating oil composition, the content of the phosphite phosphorus-containing antiwear agent is 0.1-0.8 part, and the content of the antioxidant is 0.2-0.4 part.

6. The gearbox lubricating oil composition according to claim 1, wherein The overbased zinc dialkyldithiophosphate antiwear agent comprises one or more of zinc diisooctyldithiophosphate with a base number greater than 21 mg KOH / g, zinc didecyldithiophosphate, and zinc isopropylisooctyldithiophosphate.

7. A gearbox lubricating oil composition according to claim 4, characterized in that, The phosphite phosphorus-containing antiwear agent comprises a monoalkyl phosphite, and the antioxidant is a mixture of sulfurized octyl-N-phenyl-α-naphthylamine and thio-organic amine.

8. A gearbox lubricating oil composition according to claim 1, characterized in that, In the ASTM D4172 four-ball wear test, the average wear scar diameter of the transmission lubricating oil composition tested for 1 hour is 0.25 mm or less, and the average wear scar diameter tested for 2 hours is 0.30 mm or less.

9. The gearbox lubricating oil composition according to claim 1, wherein, In the friction and wear test of the ASTM D6452 SRV testing machine, the average wear scar diameter of the transmission lubricating oil composition tested for 2 hours is 0.40 mm or less.

10. A gearbox lubricating oil composition according to claim 1, characterized in that, The lubricating oil composition can effectively improve the antiwear performance of the transmission lubricating oil and significantly reduce the traction coefficient of the oil product.

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