JP2000328084A - Gear oil composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gear oil composition for a car which shows excellence in oxidation stability at a high temperature, copper corrosion resistance, an extreme pressure property, abrasion resistance and a synchronizing property and is usable both for a manual speed change gear and a final reduction gear. SOLUTION: A base oil having kinematic viscosity of 2 to 80 mm2s at 100 deg.C contains, as essential components, (A) 0.1 to 10 wt.% of not less than one of dialkyl trisulfides represented by formula I, formula I: R1-S-S-S-R1 (wherein R1 is a hydrocarbon group) (B) 0.1 to 5 wt.% of not less than one of dithiophosphoric esters represented by general formula II formula II: (R2O)2P(=S) SR3 (wherein R2 and R3 are each a group independently selected from hydrocarbon groups) and (C) 0.1 to 5 wt.% of not less than one of phosphorus compounds selected from an acidic phosphate, a phosphite and an alkylamine salt thereof represented by formula III. formula III: (R4O)nP(=O)(OH)3-n (wherein R4 is a hydrocarbon group; and n is 1, 2 or 3).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a gear oil composition and, more particularly, to excellent oxidation stability at high temperatures (150 ° C. or higher), copper corrosion resistance at high temperatures (150 ° C. or higher), extreme pressure resistance, and the like.
The present invention relates to a dual-purpose gear oil composition for automobiles having abrasion resistance, pitting resistance, and synchro properties, and capable of lubricating a manual transmission and a final reduction gear.

[0002]

2. Description of the Related Art Since gears for automobiles are used under high-speed and high-load conditions, gear oils used for them must be excellent in anti-seizure properties and abrasion resistance. Therefore, in order to enhance anti-seizure properties, sulfurized olefins,
There is a gear oil to which a sulfur-based additive represented by a sulfurized oil or the like is added. Further, there is a gear oil (sulfur-phosphorus gear oil) to which a phosphorus-based additive such as a phosphoric acid ester or an amine salt of a phosphoric acid ester is added to enhance anti-wear properties, and a gear oil to which zinc alkyldithiophosphate is added. . The manual transmission has an extreme pressure level containing a mild sulfur-phosphorus extreme pressure agent or zinc alkyldithiophosphate API.
GL-3 or GL-4 gear oil is used, and the final reduction gear is required to have high extreme pressure.
Gear oil of API GL-5 or higher containing a phosphorus-based extreme pressure agent is used. Therefore, since the required performances of the gear oils used for the manual transmission and the final reduction gear are different from each other, the manual transmission oil is used for the manual transmission and the final reduction gear oil is used for the final reduction gear. However, there is a strong demand in the market for maintenance-free and simplified oil management, and a dual-purpose oil that can lubricate a manual transmission and a final reduction gear with one type of gear oil has been desired.

[0003] Gear oil compositions that can be lubricated for both a manual transmission and a final reduction gear have been known.
Preprints of the Automotive Engineering Society Academic Lecture, 1992, Volume 2, 9
No. 24, p. 65, a sulfur-phosphorus extreme pressure agent,
A composition combining an antioxidant and a detergent, a sulfur-phosphorus extreme pressure agent described in JP-A-9-132790, a composition combining an alkali metal borate hydrate and a zinc alkyldithiophosphate, and JP-A-10-
No. 3,169,872 discloses a composition in which a sulfur compound such as hydrogen sulfide, terpene or sulfur oil is combined with an acidic phosphoric acid ester and an amine salt thereof.

In recent years, the ratio of high-speed operation has increased due to the development of expressways, the expansion of courier services nationwide, and the rapid increase in demand for high-speed transportation, and the gear unit has been required to increase engine output and improve aerodynamic characteristics. Due to downsizing of gears, gear oil temperatures of manual transmissions and final reduction gears have been significantly increased. The conventional gear oil composition which can be lubricated for both a manual transmission and a final reduction gear has insufficient stability at high temperatures (150 ° C. or more) of the sulfur compound used, and decomposes at high temperatures to lubricate. Significantly reduce the oxidative stability of the oil composition,
Problems such as corrosion and sludge formation on metals, particularly copper, occur, and as a result, wear and seizure of gear tooth surfaces are promoted. Further, in the manual transmission, the synchronizer ring and the gear cone portion of the synchromesh mechanism cause a reduction in friction coefficient or abnormal wear, causing failure in synchronization, an increase in shift force, and an inability to shift if forced. Sometimes.

[0005]

In view of the above background, an object of the present invention is to provide excellent oxidation stability at high temperatures (150 ° C. or higher), copper corrosion resistance, extreme pressure resistance, abrasion resistance, and synchro properties. Another object of the present invention is to provide a gear oil composition for automobiles, which has lubrication and can lubricate a manual transmission and a final reduction gear in common.

[0006]

Means for Solving the Problems As a result of repeated studies to solve the above problems, the present inventors have found that dialkyl trisulfide, dithiophosphate, acid phosphate and its alkylamine salt are added to a specific base oil. Further, by combining an alkenyl succinimide derivative as needed, a high temperature (150 ° C. or higher) can be obtained while having the same extreme pressure property and abrasion resistance as compared with the case where a conventional sulfur-phosphorus extreme pressure agent is used. It has been found that the oxidation stability and copper corrosion resistance of (1) are significantly improved. Furthermore, it has been found that by using this combination, good synchro characteristics can be obtained.

That is, a first aspect of the present invention is to provide a base oil having a kinematic viscosity at 100 ° C. of from ² to 80 mm ² s ^-1 by the general formula (A):

Embedded image R ¹ —S—S—S—R ¹ ... (1) One or two represented by the formula (1) wherein R ¹ is a hydrocarbon group.
0.1 to 10% by weight of at least one kind of dialkyl trisulfide based on the total amount of the composition, (B) a general formula:

(R ² O) ₂ P (= S) SR ³ (2) (R ² and R ³ are each independently selected from the group consisting of hydrocarbon groups) One or two
More than one kind of dithiophosphate ester is used in an amount of 0.1% based on the total amount of the composition.
1 to 5% by weight, (C) general formula:

Embedded image (R ⁴ O) _n P (＝ O) (OH) _3-n (3) (R ⁴ is a hydrocarbon group, and n is 1, 2 or 3) One or two or more phosphorus compounds selected from acidic phosphate esters, phosphite esters and alkylamine salts thereof as an essential component in an amount of 0.1 to 5% by weight based on the total amount of the composition. The present invention relates to a characteristic gear oil composition.

A second aspect of the present invention is the gear oil composition according to claim 1, further comprising (D) alkenyl succinimide or a derivative thereof in an amount of 0.1 to 5% by weight based on the total amount of the composition. About things.

The gear oil composition of the present invention comprising the above-mentioned components has the properties to be provided as a manual transmission oil, that is, excellent oxidation stability at high temperatures (150 ° C. or higher) and high temperature (150 ° C. or higher). It has excellent copper corrosion resistance, excellent extreme pressure resistance, abrasion resistance, and excellent pitting resistance, has an appropriate kinetic friction coefficient between the synchronizer ring and the gear cone part, and has a kinetic friction coefficient between the synchronizer ring and the gear cone part. Performance to be maintained over a long period of time and the performance to be provided as the final reduction gear oil, that is, excellent in extreme pressure, abrasion resistance, excellent pitting resistance, excellent oxidation stability, copper corrosion resistance It has characteristics such as excellent performance, and has the characteristic that the manual transmission and the final reduction gear can be commonly lubricated.

The base oil used in the present invention is a solvent refined base oil,
A single or a mixture of a hydrogenated base oil or a highly hydrocracked base oil. Specifically, 60 neutral oil, 100 neutral oil by solvent refining or hydrogen refining,
150 neutral oil, 300 neutral oil, 500
Neutral oils and low pour point base oils having improved low temperature fluidity by removing wax from these base oils. In addition, as a highly hydrocracked base oil, raw wax (slack wax) separated by solvent dewaxing is used as a raw material, which is hydrocracked (catalyzed cracking) in the presence of a catalyst to convert linear paraffin into branched paraffin. Viscosity index of 130 or more (typically 1)
45 to 155), or hydrogen and carbon monoxide obtained by a gasification process (partial oxidation) of natural gas (such as methane) as raw materials to form heavy linear paraffins by Fischer-Tropsch polymerization, Viscosity index 1 obtained by subjecting this to the same catalytic cracking isomerization as described above.
Lubricating base oils having 30 or more (typically 145 to 155) are included.

The base oil used in the present invention has a kinematic viscosity at 100 ° C. of ² to 80 mm ² s ⁻¹ , preferably 4 to 5 mm.
0 mm ² s ⁻¹ . Here, if the kinematic viscosity at 100 ° C. is less than 2 mm ² s ⁻¹ , the lubricating property is reduced and the seizure resistance is inferior. If the kinematic viscosity is 80 mm ² s ⁻¹ or more, the resistance due to the viscosity increases and the transmission efficiency of the gear decreases. Not desirable from a viewpoint.

The viscosity index of the base oil used in the present invention is 75 or more, preferably 80 or more. Viscosity index 7
If it is less than 5, it is not preferable as the base oil of the gear oil composition for automobiles of the present invention because of poor startability at low temperatures and poor lubricity due to a decrease in viscosity at high temperatures.

As the base oil of the present invention, mineral oil, hydrocarbon-based synthetic base oil, alkylbenzene, alkylnaphthalene, ethylene-propylene copolymer polymer, fatty acid ester-based synthetic oil, aromatic oil It can be used regardless of the type of ester-based synthetic oil,
A mixture of two or more of these can be used. Further, a mixture of the above-described mineral oil and the above-described synthetic oil at an appropriate ratio may be used.

The component (A) in the present invention has the following general formula (1)

Embedded image R ¹ —S—S—S—R ¹ (1) is a dialkyl trisulfide represented by the formula (1) wherein R ¹ is a hydrocarbon group. 0.1 to 10% by weight, preferably 0.5 to 10% by weight based on the total amount
It is 7% by weight, more preferably 1 to 5% by weight.

R ¹ is a hydrocarbon group, preferably a linear or branched saturated or unsaturated aliphatic hydrocarbon group having 2 to 20 carbon atoms, such as an alkyl group or an alkenyl group, and an aromatic group having 6 to 26 carbon atoms. Group, for example, ethyl group, 1-propyl group, 2-propyl group, n-butyl group, t-butyl group, 2-ethylhexyl group, nonyl group, dodecyl group, propenyl group , Butenyl, benzyl, phenyl, hexylphenyl and the like.

The component (B) in the present invention has the following general formula (2)

Embedded image (R ² O) ₂ P (= S) SR ³ (2) (wherein, R ² and R ³ are each independently selected from the group consisting of hydrocarbon groups) Wherein the amount of the dithiophosphate is 0.1 to 5% by weight, preferably 0.2 to 2.5% by weight, more preferably 0.3 to 1% based on the total amount of the composition. is there.

R ² and R ³ are a hydrocarbon group, preferably a straight-chain or branched saturated or unsaturated aliphatic hydrocarbon group having 2 to 20 carbon atoms, for example, an alkyl group;
Examples thereof include an alkenyl group, a cycloalkyl group, a cycloalkenyl group, an aromatic hydrocarbon group having 6 to 26 carbon atoms, and specifically, an ethyl group, a 1-propyl group, a 2-propyl group, an n-butyl group, -Butyl group, 2-ethylhexyl group, nonyl group, dodecyl group, propenyl group, butenyl group, cyclopentadienyl group, benzyl group, phenyl group, hexylphenyl group and the like.

The component (C) in the present invention has the following general formula (3)

Embedded image (R ⁴ O) _n P (＝ O) (OH) _3-n (3) (wherein R ⁴ is a hydrocarbon group, and n is 1, 2 or 3)
Which is an acidic phosphoric acid ester, a phosphite, and an alkylamine salt thereof, in an amount of 0.1 to 5% by weight, preferably 0.1 to 5% by weight, based on the total amount of the composition.
It is 5 to 4% by weight, more preferably 1 to 3% by weight.

R ⁴ is a hydrocarbon group, preferably a linear or branched saturated or unsaturated aliphatic hydrocarbon group having 4 to 20 carbon atoms, that is, an alkyl group or an alkenyl group.
Cycloalkyl group, cycloalkenyl group, 6 to 2 carbon atoms
And 6 aromatic hydrocarbon groups. Specific examples of these ester compounds include, for example, monobutyl phosphate, dibutyl phosphate, tributyl phosphate, monooctyl phosphate, dioctyl phosphate, trioctyl phosphate, dioctyl phosphite, trioctyl phosphite, and mono ( 2-
Ethylhexyl), di (2-ethylhexyl) phosphate,
Tri (2-ethylhexyl) phosphate, di (2-ethyl phosphite)
Ethylhexyl), tri (2-ethylhexyl) phosphite, didecyl phosphate, didecyl phosphite, didodecyl phosphate, tridodecyl phosphate, didodecyl phosphite, tridodecyl phosphite, tridecyl thiophosphate, trihexadecyl phosphate, Trihexadecyl phosphite, trioctadecyl phosphate, trioctadecyl phosphite, tri (octylphenyl) phosphate, tri (octylcyclohexyl) phosphate and the like can be mentioned.

The alkylamine for neutralizing these is represented by the following general formula (4)

Embedded image NR ⁵ R ⁶ R ⁷ (4) (wherein, R ⁵ , R ⁶ , and R ⁷ are each independently selected from the group consisting of a hydrocarbon group and a hydrogen atom;
At least one of them is a hydrocarbon group. ). Specific examples of these compounds include dibutylamine, octylamine, dioctylamine, laurylamine, dilaurylamine, oleylamine, dioleylamine, coconutamine, tallowamine, and the like.

The alkenyl succinimide or a derivative thereof as the component (D) in the present invention is not particularly limited, and various ones which can be used as ashless dispersants for lubricating oils can be used. Specific examples of the alkenyl succinimide or a derivative thereof include, for example, a polyolefin having a molecular weight of 300 to 3,000 such as polybutene, which is reacted with maleic anhydride to obtain monoalkenyl succinic acid, and then ethylenediamine, diethylenetriamine, dipropylenetriamine, triethylene Tetramine, imidized using a polyamine such as tetraethylenepentamine, and various alkenyl succinimides such as monoamide, diimide, and triimide, or an imide obtained by reacting an aromatic polycarboxylic acid with the obtained imide. Nos. 7-213, and JP-B-42-8014, which are partially amidated amino groups of, for example, those obtained by reacting polybutene having a molecular weight of 900 with maleic anhydride and then imidizing with tetraethylenepentamine. Gazette JP-A-51-52831, JP-Sho 51-13
No. 0408, a boron compound derivative of an alkenyl succinimide, an organic phosphonate derivative or the like, or an alkenyl succinimide obtained by reacting an alkenyl succinimide with an aldehyde, ketone, carboxylic acid, sulfonic acid, alkylene oxide, sulfur or the like And the like. Preferred among these alkenyl succinimides or derivatives thereof are alkenyl succinic monoimides obtained by reacting polybutene having a molecular weight of 600 to 1,000 with maleic anhydride and then imidizing with tetraethylenepentamine. These alkenyl succinimides or derivatives thereof may be used alone or in combination of two or more. The addition amount is 0.1 to 5% by weight, preferably 0.2 to 4% by weight, more preferably 0.5 to 3% by weight based on the total amount of the composition.

The base oil of the present invention contains the above-mentioned mineral oil or synthetic oil as a main component. However, in order to actually use it as a gear oil, it is preferable to add known base oils to this base oil as necessary. Agents can be used. Examples of these additives include friction modifiers such as molybdenum dithiophosphate, molybdenum disulfide, aliphatic amines, higher alcohols, higher fatty acids, fatty acid esters, sarcosine esters, and fatty acid amides, petroleum sulfonates, alkylbenzene sulfonates, and dialkylnaphthalenes. Rust inhibitors such as sulfonates, metal deactivators such as benzotriazole and benzothiadiazole, metal detergents such as alkaline earth metal sulfonates, alkaline earth metal phenates, alkaline earth metal salicylates, alkaline earth metal phosphonates, and silicones , A viscosity index improver such as polymethacrylate, polyisobutylene, and polystyrene, a pour point depressant, and other various additives can be used alone or in combination of two or more. The content of the friction modifier is usually 0.01 to 5% by weight, the content of the rust inhibitor is usually 0.1 to 10% by weight, and the content of the metal deactivator is usually 0.001 to 5% by weight. %, The content of the viscosity index improver is usually 0.1 to 20% by weight, the content of the defoamer is usually 0.00001 to 0.1% by weight, and the content of the other additives is usually It is 0.01 to 10% by weight (all based on the total amount of the composition).

The gear oil composition of the present invention can be preferably used as a combined gear oil capable of lubricating a manual transmission and a final reduction gear.

[0024]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.

Examples and Comparative Examples Table 1 shows the compositions of the gear oil compositions used in the examples, and Table 2 shows the compositions of the gear oil compositions used in the comparative examples. Table 3 shows the performance evaluation results of the gear oil compositions used in the examples, and Table 4 shows the evaluation results of the gear oil compositions used in the comparative examples. The viscosity and performance of these gear oil compositions were evaluated by the following tests and performance evaluation tests.

(Kinematic viscosity at 100 ° C.) JIS K
It was measured by the test method specified in 2283.

(Oxidation stability test) JIS K 2514
The test was carried out under the conditions of a test oil temperature of 150 ° C., a test time of 96 hours and a test time of 192 hours in accordance with the method of oxidizing stability test for lubricating oil for internal combustion engines (ISOT) specified in 3.1. Evaluation,
The change rate of the kinematic viscosity at 100 ° C., the total acid value change rate, and the pentane-insoluble content of the test oil after the test were measured.

(Copper plate corrosion test) JIS K 2513
The test was performed under the conditions of a test oil temperature of 150 ° C. and a test time of 3 hours in accordance with the test method specified in the above.

(Extreme pressure test) In accordance with the test method for shell 4 ball extreme pressure specified in ASTM D2783, the test was carried out under the conditions of an initial oil temperature of 24 ° C, a shaft rotation speed of 1800 rpm, and a test time of 10 seconds. The initial seizure load and the fusion load were measured.

(Abrasion resistance test) ASTM D 4172
Initial oil temperature 80 ° C., shaft rotation speed 1800 rpm, load 40 kg, according to the shell 4 ball wear resistance test method specified in
f, The test was performed under the conditions of a test time of 60 minutes. For the evaluation, the diameter of the wear mark formed on the test ball after the test was measured.

(Pitching resistance test) In accordance with the uni-steel bearing rolling fatigue test method specified in IP305,
Test oil temperature 120 ° C, rotation speed 1500 rpm, load 100
The test was carried out at 0 kgf using NSK5110 bearings (six balls). Evaluation iterates 10 times the test was conducted determined by calculation L ₁₀ and L ₅₀ in the Weibull plot.

(Synchro characteristic test) JP-A-9-1327
Evaluation was made by the following method described in JP-A-90. The synchronizer ring and the gear cone are set on a table, and the rotation speed of the gear cone is maintained at 1200 rpm by a motor. Next, the synchronizer ring is pressed with a load of 40 kgf. Thereafter, the load on the synchronizer ring is removed, and the synchronizer ring is separated from the gear cone. This pattern consisting of pressing and separating the synchronizer ring is repeated for 10,000 cycles. In this repetition, the torque generated when the synchronizer ring was pressed was measured to determine the dynamic friction coefficient. This dynamic friction coefficient is calculated as 100 cycles and 1
0000 cycles, and evaluated based on the level of friction coefficient. That is, those having a high friction coefficient and capable of maintaining this friction coefficient even with durability were regarded as having excellent synchronization characteristics.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

[Table 3]

[0036]

[Table 4]

The gear oil composition of the present invention (Examples 1, 2,
3 and 4) are evaluations of oxidative stability at 150 ° C., in which the increase in viscosity, change in total acid value, and pentane-insoluble matter are determined by conventional gear oil compositions (Comparative Examples 1, 2, 3, 4, 5, 6 ), Which indicates that the oxidation stability at this temperature is excellent. In addition, a copper plate corrosion test at a high temperature (150 ° C.) shows that the corrosiveness to copper is significantly reduced. On the other hand, the extreme pressure test and the abrasion resistance test show that the gear oil composition has abrasion resistance and pitting resistance equal to or higher than that of the conventional gear oil composition. Further, from the evaluation of the synchro characteristics, it can be seen that the dynamic friction coefficient between the synchro cone and the synchro ring shows a higher value even after 10,000 cycles than the conventional one.

[0038]

According to the present invention, excellent oxidation stability at high temperature (150 ° C. or more), copper corrosion resistance at high temperature (150 ° C. or more),
A gear oil composition having extreme pressure resistance, abrasion resistance, pitting resistance and synchro properties could be provided.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C10M 137: 08 133: 16) C10N 20:02 30:00 30:06 30:08 30:10 30:12 40:04 (72) Inventor Tetsuro Wakizono 2-3-2 Daiba, Minato-ku, Tokyo Inside Showa Shell Sekiyu KK (72) Inventor Takashi Hashimoto 3-1-1 Hinodai, Hino-shi, Tokyo F-term ( Reference) 4H104 BF03C BG12C BH02C BH03C BH05C BH06C DA02A EA02A LA03 LA04 LA05 LA06 LA20 PA02

Claims (2)

[Claims] 1. A kinematic viscosity at 100 ° C. of 2 to 80 mm.
The base oil is ² s ^-1, (A) the general formula: represented by [Chemical formula 1] ^{R 1 -S-S-S-} R 1 ...... (1) (R 1 is a hydrocarbon group) One or two
0.1 to 10% by weight of at least one kind of dialkyl trisulfide based on the total amount of the composition, (B) a general formula: (R ² O) ₂ P (= S) SR ³ (2) (R) ² and R ³ are each independently selected from the group consisting of hydrocarbon groups)
More than one kind of dithiophosphate ester is used in an amount of 0.1% based on the total amount of the composition.
1 to 5% by weight, (C) a general formula: (R ⁴ O) _n P (＝ O) (OH) _3-n (3) (R ⁴ is a hydrocarbon group, and n is 1, 2 or 3), wherein one or more phosphorus compounds selected from acidic phosphates, phosphites and alkylamine salts thereof are used in an amount of 0.1 to 2% based on the total amount of the composition. A gear oil composition comprising 5% by weight as an essential component. 2. The gear oil composition according to claim 1, further comprising (D) alkenyl succinimide or a derivative thereof in an amount of 0.1 to 5% by weight based on the total amount of the composition.