JPH07258674A - Gear oil composition for automobile - Google Patents

Abstract

PURPOSE:To obtain a gear oil composition for automobiles capable of commonly lubricating a manual transmission and LSD-mounted reduction gear improved in extreme-pressure property, abrasion resistance, synchronous characteristics, oxidation stability and LSD performance. CONSTITUTION:This gear oil composition for automobile contains one or more kinds of oils selected from mineral oils and synthetic oils and used as base oils, (A) 5-15wt.% of a sulfur-phosphorus-based extreme-pressure agent, (B) 0.5-10wt.% of an alkali metal borate hydrate and (C) 0.1-5wt.% of an alkaline earth metal type cleaning and dispersing agent or these components and (D) 0.05-5wt.% of one or more kinds of compound selected from saturated or unsaturated 7-30C aliphatic carboxylic acids or aromatic carboxylic acids, esters of these carboxylic acids and raction products of these carboxylic acids and organic amines.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear oil composition for automobiles, and more particularly, to a manual transmission having improved extreme pressure, wear resistance, synchro characteristics, oxidation stability, and LSD performance, and final deceleration with LSD installed. The present invention relates to a so-called dual-purpose gear oil composition for automobiles, which can be commonly lubricated.

[0002]

2. Description of the Related Art Since automobile gears are used under high speed and high load conditions, the gear oil used for them has anti-seizure property,
It must have excellent wear resistance.

Therefore, the conventional gear oil contains a sulfur-based additive such as a sulfurized olefin-based additive for enhancing the seizure-preventing property, and a phosphoric acid ester or a phosphoric acid ester for enhancing the anti-wear property. Gear oil to which a phosphorus-based additive such as an amine salt of is added (that is, sulfur-phosphorus <<
It may be described as "SP type">> Gear oil containing an extreme pressure agent) has been used.

For example, a manual transmission uses a multigrade gear oil containing a mild sulfur-phosphorus extreme pressure agent and having an extreme pressure level of GL-3 to GL-4, while a final reduction gear has a high grade. Since extreme pressure is required, highly active sulfur-
Gear oils containing a phosphorus-based extreme pressure agent and having an extreme pressure level of GL-5 or higher are used.

On the other hand, the gear oil used for a mechanical LSD gear using a friction clutch (hereinafter, referred to as "LSD gear oil") has a high reduction speed because a final reduction gear is incorporated in the LSD gear. Needs pressure,
In order to suppress abnormal vibration and noise due to stick slip in the friction plate, excellent friction characteristics are required. Therefore, LSD gear oil contains GL-5
The above sulfur-phosphorus extreme pressure agent and the friction modifier are blended.

As described above, the gear oils used for the manual transmission and the final reduction gear (including those mounted on the mechanical LSD gear) have different required performances. Final reduction gear oil is used for machine oil and final reduction gear, and LSD gear oil is used for LSD gear.

In recent years, the proportion of high-speed operation has increased due to the development of expressways and the rapid increase in demand for high-speed transportation such as courier service. Also, the gear section is shielded from the viewpoint of high engine output and aerodynamic characteristics, and fuel consumption is improved. Due to downsizing of the gear unit and the like from the viewpoint of improvement, the gear oil temperature of the manual transmission and the final reduction gear has been remarkably increased.

[0008]

From such a background,
Conventionally used sulfur-phosphorus extreme pressure agents cause problems such as oil deterioration due to insufficient heat resistance, metal corrosion, sludge formation, and problems such as gear tooth surface wear and seizure. .

Further, when these gear oil compositions are used, the synchronizer ring and the gear cone portion in the synchromesh mechanism have a reduced friction coefficient or abnormal wear, fail to synchronize, increase the shift force, and eventually shift the gear. There is a problem such as not being able to.

In order to improve the shift operability, various lubricating oil compositions have been proposed (JP-A-62-192).
No. 495, No. 63-61090, No. 63-61091.
No. However, these compositions
Since P is an essential component, there is a drawback that the copper alloy is easily corroded at high temperature or sludge is easily generated.

Further, with the recent increase in the number of RV vehicles (leisure vehicles), mechanical LSD gears using friction plates have been receiving attention again. In this RV vehicle, the usage conditions are severe, and the oil temperature tends to rise particularly. Therefore, the SP additive added to gear oil and the friction modifier (FM) added for the purpose of imparting LSD performance deteriorate due to exposure to high temperatures, and sludge is generated in the oil. This may cause gear damage, and even the FM that initially shows good LSD performance loses its effect as it is used, causing troubles such as abnormal vibration and abnormal noise due to stick-slip in the friction plate. Is occurring.

As described above, the manual transmission, the final reduction gear, the L
The required performance of the gear oil used for SD is different, and the gear oil is used properly according to the place of use.

On the other hand, recently, there is a strong demand for maintenance-free and rationalization of oil management, and a single type of gear oil that can be lubricated is desired. However, at present, there is no gear oil having all the performances on the market, and it is strongly desired to develop a dual-purpose oil.

The present invention has been made in order to meet such a demand, and has excellent extreme pressure resistance, wear resistance, synchro characteristics, oxidation stability, and LSD performance, and therefore a manual transmission and an LSD mounting end. An object of the present invention is to provide a gear oil composition for automobiles, which can be lubricated in common with a speed reducer.

[0015]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that the sulfur-phosphorus extreme pressure agent as the component (A) and the component (B) as described below. A composition in which the alkali metal borate hydrate of, and an alkaline earth metal-type detergent dispersant as the component (C) are blended,
Due to the interaction of these compounding agents, heat resistance, wear resistance,
The present invention has been found to have excellent seizure resistance, corrosion resistance, and shift operability, and that the addition of a friction modifier as the component (D) together with these components (A) to (C) improves the LSD performance. Has been completed.

That is, according to the present invention, (A) a sulfur-phosphorus extreme pressure agent is added to a base oil composed of mineral oil and / or synthetic oil.
15% by weight, (B) alkali metal borate hydrate 0.5
10 to 10% by weight and (C) 0.1 to 5% by weight of an alkaline earth metal type detergent dispersant, or (D) saturated or added in addition to these (A) to (C). One or more selected from unsaturated carboxylic acids having 7 to 30 carbon atoms or aromatic carboxylic acids, esters of these carboxylic acids, and reaction products of these carboxylic acids and organic amines, 0.05 to 5% by weight, The gist is an automotive gear oil composition characterized by being blended.

The gear oil composition of the present invention comprising the above components has the performance to be provided as a manual transmission oil, that is,
(1) The synchronizer ring and the gear cone portion have a high friction coefficient, (2) the friction coefficient is maintained for a long period of time, (3) the heat resistance is excellent, that is, the performance that the final reduction gear oil should have, that is, , (1) Extreme pressure resistance and abrasion resistance, (2) Excellent heat resistance, that is, the performance that should be provided as LSD gear oil, that is, (1) Excellent stick-slip resistance, (2) (1) Of the manual transmission (front diff, front diff, which is excellent in the extreme pressure resistance and wear resistance, and (4) excellent in heat resistance.
It is possible to lubricate both the four-wheel drive manual transmission with the integrated center differential) and the final reduction gear with the LSD.

The gear oil composition of the present invention will be described in more detail. One preferred embodiment thereof is a mineral lubricating oil having a viscosity at 100 ° C. of about 1 to 50 cSt or a purified product thereof (collectively, [mineral oil]). , And 10
One or more lubricants selected from synthetic lubricants having a viscosity of about 1 to 50 cSt at 0 ° C. (referred to as “synthetic oil”) are used as the base material, and the component (A) is added to ~ 1
5% by weight, preferably about 6-9% by weight, component (B) 0.5-10% by weight, preferably about 2-5% by weight,
0.1 to 5% by weight of component (C), preferably about 0.5 to
It is a mixture of 3% by weight. Or these (A) ~
In addition to the component (C), 0.05 to 5 parts by weight of the component (D),
It is preferably blended at a ratio of about 0.1 to 3% by weight.

If the amount of the component (A) is too small, the gear performance (extreme pressure property) will deteriorate. If too much, this effect is saturated and is economically disadvantageous. If the amount of component (B) is too small, the effects of thermal stability and oxidative stability will be weakened, and it will be prone to deterioration and the synchro performance will be reduced. If too much, these effects are saturated and economically disadvantageous. If the amount of component (C) is too small, the coefficient of friction between the synchronizer ring and the gear cone portion will not increase, and if it is too large, extreme pressure properties and wear resistance will decrease. If the component (D) is too small, when used in the LSD-mounted final reduction gear, there is no friction reducing effect, and abnormal vibration or noise occurs. If the amount is too large, not only the extreme pressure property is lowered and the additive is separated and precipitated, but also the defoaming property and the oxidation stability are adversely affected.

As the above-mentioned component (A), one containing sulfur and phosphorus in one compound (this compound may be referred to as "sulfur-phosphorus extreme pressure agent") may be used. A so-called sulfur-based extreme pressure agent containing either one of them and a phosphorus-based extreme pressure agent may be mixed and used.

As the sulfur-based extreme pressure agent, a hydrocarbon sulfide represented by the general formula of Chemical formula 1, a terpene sulfide, a sulfurized fat and oil which is a reaction product of fat and sulfur, and the like are used.

[0022]

Embedded image R ¹ -S _x- (R ² -S _x ) _n -R ¹

In the general formula of Chemical formula ¹ , R ¹ is a monovalent hydrocarbon group and R ² is a divalent hydrocarbon group. x is an integer of 1 or more, preferably 1 to 8, and each x in the repeating unit may be the same or different. n is 0
Alternatively, it is an integer of 1 or more.

In the hydrocarbon sulfide represented by the general formula of Chemical formula ¹ , R ¹ is a linear or branched saturated or unsaturated aliphatic hydrocarbon group having 2 to 20 carbon atoms (for example, an alkyl group or an alkenyl group). Group), an aromatic hydrocarbon group having 6 to 26 carbon atoms, and specifically, an ethyl group, a propyl group, a butyl group, a nonyl group, a dodecyl group, a propenyl group,
Examples thereof include butenyl group, benzyl group, phenyl group, tolyl group, hexylphenyl group and the like.

R ² is a linear or branched saturated or unsaturated aliphatic hydrocarbon group having 2 to 20 carbon atoms, and 6 carbon atoms.
To 26 aromatic hydrocarbon groups, and specific examples thereof include an ethylene group, a propylene group, a butylene group, and a phenylene group.

Typical examples of the hydrocarbon sulfide represented by the general formula of Chemical formula 1 are sulfur olefin and general formula R ¹ -S.
_x -R ¹ (x is an integer of 2 or more) is a polysulfide compound represented by the. Specifically, diisobutyl disulfide, dioctyl polysulfide, ditersharinonyl polysulfide, ditertiary butyl polysulfide, ditertiary benzyl polysulfide, and sulfurized olefins obtained by sulfurizing olefins such as polyisobutylene and terpenes with sulfur and other sulfiding agents. And so on.

Sulfurized fats and oils, which are reaction products of fats and oils, use animal and vegetable fats and oils such as lard, beef fat, whale oil, palm oil, coconut oil and rapeseed oil as fats and oils.
This reaction product is not a single chemical structure but a mixture of various compounds, and the chemical structure itself is not clear.

As the phosphorus-based extreme pressure agent or the sulfur-phosphorus-based extreme pressure agent, the phosphoric acid ester, phosphorous acid ester, thiophosphoric acid ester, diotilic acid ester, and the like represented by the general formula of Chemical formula 2 are used. To be

[0029]

Embedded image (R ³ ) _a H _3-a X ₃ PX _b

In the general formula of Chemical formula 2, R ³ is a monovalent hydrocarbon group, and X is an oxygen atom or a sulfur atom. a is 1,
In 2 or 3, b is 0 or 1.

As the group R ³ , a linear or branched saturated or unsaturated aliphatic hydrocarbon group having 5 to 20 carbon atoms (for example, an alkyl group or an alkenyl group), an aromatic group having 6 to 26 carbon atoms Examples thereof include a hydrocarbon group and a cycloalkyl group.

Specific examples of the ester compound represented by the above chemical formula 2 include monooctyl phosphate, dioctyl phosphate, trioctyl phosphate, dioctyl phosphite, trioctyl phosphite, dioctyl thiophosphate, trioctyl thiophosphate and phosphorus. Didecyl acid, Didecyl phosphite, Didodecyl phosphate, Tridodecyl phosphate, Didodecyl phosphite, Tridodecyl phosphite, Tridecyl thiophosphate, Trihexadecyl phosphate, Trihexadecyl phosphite, Trihexadecyl thiophosphate, Phosphorus Trioctadecenyl acid, trioctadecenyl phosphite, trioctadecenyl thiophosphate, tri (octylphenyl) phosphate, tri (octylphenyl) phosphite, tri (octylphenyl) thiophosphate, phosphorus Acid tri (octylcyclohexyl), trithiodithiophosphate Le and the like.

Further, as the phosphorus-based extreme pressure agent, it is also possible to use an acidic phosphoric acid ester, an acidic phosphorous acid ester, an acidic thiophosphoric acid ester, an alkylamine salt of an acidic dithiophosphoric acid ester, or the like represented by the general formula of Chemical formula 2. it can.

Specific examples of these amine salts include butyl acid phosphate, 2-ethylhexyl acid phosphate, octyl acid phosphate, lauryl acid phosphate, oleyl acid phosphate and tolyl acid phosphate as the acidic ester.

Alkylamines for neutralizing these are represented by the general formula NR ⁴ R ⁵ R ⁶ (in the formula, R ⁴ , R ⁵ and R
⁶ is a monovalent hydrocarbon group or a hydrogen atom, at least one of which is a hydrocarbon group), and specific examples of these compounds include dibutylamine, octylamine, dioctylamine, laurylamine and dilauryl. Amine,
Examples include coconut amine and tallow amine.

The alkali metal borate hydrate which is the component (B) can be produced by the method disclosed in, for example, Japanese Patent Publication No. 53-9763 and US Pat. No. 3,929,650. .

That is, an aqueous solution of potassium hydroxide and boric acid is treated with a neutral alkaline earth metal sulfonate or succinimide ashless type so that the atomic ratio of boron / potassium is 2.5 to 4.5. A fine particle dispersion of potassium borate hydrate obtained by adding water to an oil solution containing a dispersant and stirring vigorously to form a water-in-oil emulsion, and dehydrating the emulsion can be used.

As another production method, an alkali metal or alkaline earth metal neutral sulfonate is carbonated in the presence of an alkali metal hydroxide to obtain a superbasic sulfonate, which is reacted with boric acid. It is also possible to use the resulting fine particle dispersion of alkali metal borate. In this case, the carbonation reaction may be carried out in the presence of an ashless dispersant such as succinimide.

The alkali metal borate hydrate which is the component (B) is more preferably potassium borate produced using an ashless dispersant such as neutral calcium sulfonate and succinimide as a starting material. Or a sodium borate dispersion may be mentioned. Alkali metal borate hydrates obtained by these methods are described, for example, by the formula K
₂ O ・ 3B ₂ O ₃・ 3.2H ₂ O or Na ₂ O ・ B
It is represented by ₂ O ₃ · 2.0H ₂ O.

As the alkaline earth metal type detergent-dispersant which is the component (C), known ones generally used in engine oils can be used. That is, sulfonate, phenate, salicylate, phosphonate, etc.,
It is in the form of a metal salt with alkaline earth metals such as calcium, magnesium and barium. Furthermore, a superbasic detergent dispersant containing an excessive amount of these hydroxides or carbonates of alkaline earth metals can also be used.

Further, the component (D) is (1) a saturated or unsaturated aliphatic carboxylic acid having 7 to 30 carbon atoms or an aromatic carboxylic acid, (2) an ester of the carboxylic acid of the above (1), (3) ) One or more selected from the reaction product of the above-mentioned (1) carboxylic acid and organic amine.

In the above (1), examples of the aliphatic carboxylic acid include epulinic acid, stearic acid, oleic acid, linoleic acid and erucic acid, and examples of the aromatic carboxylic acid include benzoic acid and salicylic acid. And so on.

Examples of the carboxylic acid ester (2) include esters of the above-mentioned aliphatic carboxylic acids or aromatic carboxylic acids with monohydric alcohols. Examples of the monohydric alcohol include butyl, octyl, lauryl, stearyl, and oleyl alcohol. Specific compounds include oleyl caprate, octyl palmitate, amyl stearate, lauryl oleate, and lauryl linoleate.

Further, examples of the carboxylic acid ester of (2) include monodiesters of the above-mentioned aliphatic carboxylic acids and divalent to hexavalent alcohols. Specific examples of these polyhydric alcohols are glycol glycerin, trimethylolpropane, pentaerythritol, etc.,
Specific examples of monodiesters are sorbitan monolaurate, sorbitan dilaurate, sorbitan monooleate, sorbitan dioleate, sorbitan monostearate, sorbitan distearate and the like.

Further, as the reaction product of the carboxylic acid and the organic amine in the above (3), the above-mentioned aliphatic carboxylic acid or aromatic carboxylic acid, monoethanolamine, monopropanolamine, diethanolamine, dipropanolamine , Diisopropanolamine, alkanolamines such as triethanol, diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, tetrapropylenepentamine, hexabutyleneheptaamine, hexaethyleneheptaamine, heptaethyleneoctaamine and other polymethylenepolyamines The reaction product of

In the gear oil composition of the present invention, the above (A)
In addition to the three components of (C) or the four components of these three components and (D), known additives such as an ashless dispersant, an antiwear agent, and Friction modifiers, antioxidants, corrosion inhibitors, viscosity index improvers, pour point depressants, defoamers and the like can be added.

Examples of the ashless dispersant include alkenyl succinimide, alkenyl succinic acid ester, amide of long chain fatty acid and polyamine (aminoamide type), and the like.
ZnDTP and the like as antiwear agents, organic molybdenum compounds and the like as friction modifiers, amine-based and phenol-based antioxidants and the like as antioxidants, and benzotriazole, alkenyl succinic acid esters and the like as corrosion inhibitors However, examples of the viscosity index improver include polymethacrylate and olefin copolymer, examples of the pour point depressant include polymethacrylate, and examples of the defoaming agent include silicon compound and ester defoaming agent.

[0048]

【Example】

Examples 1 to 6 and Comparative Examples 1 to 7 Paraffin-based lubricating base oil (500 neutral) was blended with various additives shown in Tables 3 to 6 at the ratios shown in Tables 3 to 6 to compare the present invention and the comparison. The gear oil compositions of Example 1 were prepared, and the following performance tests were performed on these gear oil compositions and the commercially available gear oils shown in Table 7. The results are shown in Tables 3-7.

[Synchronization characteristic evaluation test] First, a synchronizer ring and a gear cone are set on a table, and the rotation speed of the gear cone is maintained at 1200 rpm by a motor. Then, the synchronizer ring is pressed with a load of 40 kgf. Then remove the load on the synchronizer ring and disconnect the synchronizer ring from the gear cone. This pattern consisting of pressing and disconnecting the synchronizer ring is repeated 10,000 cycles.

In this repetition, the torque generated when the synchronizer ring was pressed was measured to determine the friction coefficient. This friction coefficient is 100 cycles and 10
000 cycles were compared to evaluate the friction coefficient. That is, those having a high friction coefficient and being able to maintain this high friction coefficient even after the endurance were made to have excellent synchro characteristics.

[Extreme Pressure Test] IAE under the conditions shown in Table 1.
A gear test was conducted. The IAE gear test was performed according to IP166 / 68 of the IP (British Petroleum Institute) method to measure the seizure limit load.

[0052]

[Table 1]

[Oxidation stability test] In accordance with the lubricating oil stability test method for internal combustion engines (JIS K 2514), 150
It was carried out under the conditions of 48 ° C for 48 hours. The evaluation was performed by increasing the total acid value and the presence or absence of sludge.

[LSD Performance Evaluation Test] New and deteriorated oils of the gear oil compositions of the present invention and the comparative one (according to the lubricating oil oxidation stability test for internal combustion engine, forced deterioration is performed at 150 ° C. for 24 hours. What is the LSD performance test?
A low speed sliding friction test was conducted according to the following procedure.

That is, a predetermined number of friction plates and friction discs used in the LSD are fixed on the friction plates and rotatable on the friction discs. The friction coefficient was determined by detecting the torque when the friction disc was rotated under the conditions shown in Table 2 while sliding the friction plate surface while applying a constant load with air pressure.

[0056]

[Table 2]

In the evaluation of the LSD performance, it can be said that the LSD performance is good if the friction coefficient does not increase at 5 to 1 rpm. Further, if the friction coefficient (μ) of the deteriorated oil does not increase at 5 to 1 rpm, it means that the maintainability of the LSD performance is good. Therefore, the evaluation of the LSD performance was performed at a slip speed of 1
The friction coefficient μ1 at the time of rpm and the friction coefficient μ10 at the sliding speed of 10 rpm were used as the ratio, and those having a value of μ1 / μ10 smaller than 1.00 were considered to have excellent LSD performance.

Note that * 1 to * 4 in Tables 3 to 7 have the following meanings. * 1: SP type package type additive (S = 22.9% by weight, P = 1.4% by weight), * 2: Potassium borate dispersed in oil with an ashless type dispersant (boron Content of 7.6% by weight), * 3: succinimide ashless dispersant, * 4: polymethacrylate (weight average molecular weight 40,000),

[0059]

[Table 3]

[0060]

[Table 4]

[0061]

[Table 5]

[0062]

[Table 6]

[0063]

[Table 7]

As is clear from Tables 3 to 7, the gear oil compositions of the present invention (Examples 1 to 3) are the comparative gear oil compositions (Comparative Examples 1 to 3) and the commercially available SP type gear oils ( As compared with Comparative Example 6), it can be seen that while maintaining the same or higher extreme pressure properties, the oxidation stability is good and the synchro characteristics are also excellent. Further, the gear oil composition of the present invention (Examples 4 to
6) is superior in oxidation stability while maintaining the extreme pressure property equal to or higher than that of the comparative gear oil composition (Comparative Examples 4 to 5) and the commercially available LSD gear oil (Comparative Example 7), and the synchro characteristic. It can be seen that the LSD performance is also very good.

[0065]

As described in detail above, according to the gear oil composition of the present invention, the sulfur-phosphorus extreme pressure agent as the component (A) and the alkali metal salt borate as the component (B). Japanese food,
By the synergistic effect with the alkaline earth metal type detergent-dispersant as the component (C), both extreme pressure property and oxidation stability, which have hitherto been difficult, can be made compatible and the synchro characteristic can be improved. Thereby, it is possible to provide gear oil that can lubricate the manual transmission and the final reduction gear in common, contribute to longer drainage, and contribute to labor saving by simplifying inventory management.

In addition to the above components (A) to (C),
By blending the component (D), excellent LSD performance can be maintained for a long period of time, and the final reduction gear equipped with the LSD can be favorably used. This makes it possible to lubricate all gear parts used in automobiles, which is effective in inventory management.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C10M 133: 06 129: 95) C10N 10:02 10:04 10:06 30:06 30:10 40 : 04 (72) Inventor Yukio Okano 1134-2 Gongendo, Satte City, Saitama Cosmo Research Institute Co., Ltd. (72) Inventor Satoshi Masuda 1134-2 Gongendo, Satte City, Saitama Cosmo Co., Ltd. (72) Inventor Ikuo Fukuhara, 134-2 Gongendo, Satte City, Saitama Cosmo Research Institute, Ltd. Research and Development Center

Claims (2)

[Claims] 1. A base oil comprising at least one selected from mineral oils and synthetic oils, to which (A) a sulfur-phosphorus extreme pressure agent 5 is added.
˜15% by weight, (B) alkali metal borate hydrate 0.
An automotive gear oil composition comprising 5 to 10% by weight and (C) an alkaline earth metal type detergent-dispersant of 0.1 to 5% by weight. 2. A base oil comprising at least one selected from mineral oils and synthetic oils, and (A) sulfur-phosphorus extreme pressure agent 5
˜15% by weight, (B) alkali metal borate hydrate 0.
5 to 10% by weight, (C) 0.1 to 5% by weight of an alkaline earth metal type detergent-dispersant, and (D) a saturated or unsaturated C 7 to C 30 aliphatic or aromatic carboxylic acid, One or more selected from esters of these carboxylic acids and reaction products of these carboxylic acids with organic amines.
An automotive gear oil composition, characterized in that it comprises from 05 to 5% by weight.