JPH06220475A - Gear oil composition - Google Patents

Abstract

(57) [Summary] [Purpose] In addition to high extreme pressure and wear resistance equivalent to or better than conventional gear oils containing SP-based extreme pressure agents, gears with excellent oxidation stability and fuel efficiency. Provide oil. [Structure] At least one selected from mineral oil and synthetic oil is used as a base oil, and (A) an alkali metal borate hydrate having a boron content of 0.07 to 1.5% by weight (hereinafter,%), ( B) 0.1 to 10% of at least one organic molybdenum compound represented by the formula (1) is contained. [Chemical 1] Further, together with the above-mentioned components (A) and (B), as component (C), (1) phosphoric acid ester, phosphorous acid ester, amine salts thereof, and (2) hydrocarbon sulfide represented by the formula (2) 1.0 to 10% of one or more kinds selected from the following: a sulfurized oil and fat, which is a reaction product of (3) oil and fat and sulfur. [Chemical 2]

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile or industrial gear oil composition used in automobiles or industrial machines, and more specifically, to extreme pressure resistance, abrasion resistance, oxidation stability,
The present invention relates to an economical molybdenum-containing gear oil composition having improved fuel economy.

[0002]

2. Description of the Related Art Since automobile gears are exposed to high-speed rotation and high-load use environment, the gear oil used for them is
It is required to have excellent extreme pressure and wear resistance. By the way, API service classification is applied to the quality grade of the gear oil for automobiles. For example, GL-3 or GL-4 class gear oil is used in a manual transmission, and G is used in a final reduction gear that has a higher load than a manual transmission.
L-5 class gear oil is used.

Further, industrial gear oils used for bearings and gears of industrial machines include a first type for relatively light loads and a second type for relatively medium and high loads. The extreme pressure property of the second type industrial gear oil corresponds to about GL-3 in API service classification of automobile gear oil. Gear oils used for bearings and gears of these industrial machines are also required to have improved wear resistance and extreme pressure due to the recent increase in size of industrial machines and high-speed, high-load operation. Further, for the purpose of energy saving, the friction loss has been reduced by blending a friction modifier.

At present, these automotive or industrial gear oils contain a sulfur-based additive for enhancing extreme pressure property and a phosphorus-based additive for enhancing abrasion resistance (that is, sulfur-phosphorus). The mainstream is a system extreme pressure agent (hereinafter referred to as "SP type extreme pressure agent") (that is, SP type gear oil). Typically as this sulfur-based additive,
Sulfurized olefins, sulfides, sulfurized fats and oils are typically used as phosphorus-based additives such as phosphoric acid esters and amine salts thereof.

Generally, in order to obtain high extreme pressure, this SP
Since it is dealt with by increasing the compounding amount of the system extreme pressure agent, the compounding of the SP system extreme pressure agent is indispensable for the gear oil requiring high extreme pressure property of GL-4 class or higher. On the other hand, in a manual transmission that has a lower load than the final reduction gear, SP
Zinc dialkyldithiophosphate, which has excellent heat resistance, is used in place of the base extreme pressure agent (hereinafter referred to as "DT
A gear oil in which this metal salt is described as "M-DTP" using the element symbol M of the corresponding metal) and a metal detergent is also used.

[0006]

In recent years, with the diversification of user needs and the development of high-speed transportation networks, the demand for high performance and high speed of automobiles has been rapidly increasing. In order to meet this demand, engine output has been increased, gear parts have been shielded due to improved aerodynamic characteristics, and gear unit units have been downsized for weight reduction. Under these circumstances, the load on the automobile gear tends to increase, and along with this, the amount of heat generated by stirring resistance and friction also increases, causing the temperature of the gear oil to rise.

[0007] Therefore, it has become an important subject that the gear oil has heat resistance as well as extreme pressure resistance and wear resistance. The gear oil using the above-mentioned SP extreme pressure agent has excellent extreme pressure properties and wear resistance, but on the other hand, it easily oxidizes and deteriorates under high temperature conditions to generate sludge, which causes seizure and increase in wear. In addition, it has a problem of causing corrosion and wear of the metal surface. Therefore, the service limit temperature of SP gear oil is 120 at most.
It is set to 130 ° C.

Further, Zn-DTP has both wear resistance and antioxidation property. On the other hand, those having higher wear resistance have lower extreme pressure properties, and those having higher extreme pressure properties are more likely to promote corrosion wear. I have a problem. Moreover, when used at high temperatures, there is a drawback that sludge is easily generated.

As described above, in the conventional gear oil, the extreme pressure property and the wear resistance / oxidation stability are contradictory performances, and it is extremely difficult to achieve both of these performances at the same time. Further, from the viewpoint of energy saving and resource saving, there is a strong demand for improvement in fuel efficiency, and as a gear oil,
This is dealt with by reducing the stirring resistance by lowering the viscosity and reducing the friction resistance by adding a friction modifier. However, lowering the viscosity and adding a friction modifier have the demerits of adversely affecting extreme pressure resistance, wear resistance, and oxidation stability, so it is currently difficult to achieve both gear oil performance and fuel economy. Is.

The present invention solves various problems of the conventional countermeasures as described above, and has high oxidation resistance and wear resistance equal to or higher than that of SP gear oil, and excellent oxidation stability, An object is to provide a gear oil composition having fuel economy.

[0011]

Means for Solving the Problems As a result of repeated studies to achieve the above object, the present inventors have found that (1) mineral oil or synthetic oil-based lubricating oil which is a base material is alkali metal borate water. A composition obtained by blending a solvate and at least one organic molybdenum compound can improve all of extreme pressure resistance, abrasion resistance, and oxidation stability by the interaction thereof, and also has a friction resistance. Since it can be suppressed to a low level, it is also effective for fuel saving. (2) With this composition,
Further, by adding an SP-based extreme pressure agent that has been conventionally used, it is possible to obtain higher extreme pressure properties and heat resistance, and it is suitable as a gear oil for automobiles required to have higher extreme pressure properties and heat resistance. The present invention has been completed and the present invention has been completed.

That is, the gear oil composition of the present invention comprises at least one selected from mineral oils and synthetic oils as a base oil, to which an alkali metal borate hydrate is added as a component (A). And 0.07 to 1.5% by weight, and 0.1 to 10% by weight of at least one organic molybdenum compound represented by the general formula of Chemical formula 3 as the component (B). .

[0013]

[Chemical 3]

The gear oil composition of the present invention comprises, in addition to the above-mentioned components (A) and (B), as component (C), (1) phosphoric acid ester, phosphorous acid ester and amines thereof. A salt, a hydrocarbon sulfide represented by the general formula (2) 4,

[Chemical 4] (3) One or more selected from the group consisting of sulfurized fats and oils, which is a reaction product of fats and oils and sulfur, is also contained in an amount of 1.0 to 10% by weight.

The gear oil composition of the present invention will be described in detail. One preferred embodiment thereof is a mineral oil or a purified product thereof (collectively referred to as "mineral oil") having a viscosity at 100 ° C. of about 1 to 50 cSt. Viscosity at 100 ℃ is about 1
.About.50 cSt synthetic oil and at least one base material selected from the group consisting of 0.07 to 50 parts by weight of the component (A).
1.5% by weight, preferably about 0.3-0.8% by weight,
The component (B) is 0.1 to 10% by weight, preferably about 0.
It is a mixture of 5 to 3% by weight. In addition to these components (A) and (B), the component (C) is 1.0
It is a mixture of 10 to 10% by weight.

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

That is, an aqueous solution prepared by dissolving potassium hydroxide and boric acid so that the atomic ratio of boron / potassium is 2.5 to 4.5 is prepared by using a neutral alkaline earth metal sulfonate or succinimide system. It is possible to use a fine particle dispersion of potassium borate hydrate obtained by adding water to an oil solution containing an ashless dispersant and stirring vigorously to make a water-in-oil emulsion, and dehydrating the emulsion.

Further, 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. The carbonation reaction in this case may be carried out in the presence of an ashless dispersant such as succinimide.

The alkali metal borate hydrate in the gear oil composition of the present invention is more preferably produced by using the ashless dispersant such as neutral calcium sulfonate or succinimide according to the former production method as a starting material. Examples thereof include potassium borate and sodium borate dispersions. The alkali metal borate hydrate obtained by these methods can be represented by the formula of Chemical formula 5, for example.

[0020]

Embedded image _{K 2 O · 3B 2 O 3} · 3.2H 2 O Na 2 O · B 2 O 3 · 2.0H 2 O

Since the alkali metal borate hydrate used in the present invention is obtained in a state of being suspended in an ashless type dispersant or the like as described above, the amount of the suspension to be blended is It changes depending on the concentration. For example, when a suspension containing an alkali metal borate hydrate at a concentration of 7.6% by weight as boron is used, the suspension is about 1 to 20 with respect to the base oil.
Wt% will be added.

As the organic molybdenum compound as the component (B), known compounds which have been used conventionally can be used. In the structural formula shown in Chemical formula 3, the alkyl group of R ^{1 to} R ⁴ may be saturated or unsaturated, may be linear or branched, and is preferably propyl, butyl, pentyl, isopentyl, hexyl, 2 -Ethylhexyl,
Mo-DTP having 3 to 12 carbon atoms such as nonyl and lauryl
However, the interaction with the alkali metal borate hydrate of the component (A) is the largest, and is preferably used.

It is known that a molybdenum salt of dialkyldithiocarboxylic acid (hereinafter referred to as "Mo-DTC") also has a friction reducing effect as an additive for engine oil (JP-A-3-269094). (See), but this M
In the gear oil prepared by blending o-DTC as the component (B) with the component (A) in the base material, the above-mentioned Mo-D
The synergistic effect with the component (A) as in the case of using TP as the component (B) does not occur, and it is not possible to obtain the effect of improving the extreme pressure property, the wear resistance, and the oxidation stability and at the same time suppressing the friction resistance to a low level. .

The organic molybdenum compound having the structural formula of Chemical formula 3 includes, for example, one having the structural formula as shown in Chemical formula 6.

[0025]

[Chemical 6]

As specific examples of the organic molybdenum compound having the structural formula of Chemical formula 3, molybdenum sulfide diethyldithiophosphate, molybdenum dipropyldithiophosphate sulfide, molybdenum dibutyldithiophosphate sulfide, molybdenum dibenzyldithiophosphate sulfide, molybdenum dihexyldithiophosphate sulfide, Molybdenum sulfide dioctyl dithiophosphate, molybdenum sulfide didecyl dithiophosphate, molybdenum sulfide molybdenum didodecyl dithiophosphate, molybdenum sulfide molybdenum di (butylphenyl) dithiophosphate, molybdenum sulfide molybdenum di (nonylphenyl) dithiophosphate, molybdenum sulfide molybdenum dithiophosphate, oxymolybdenum dipropyl dithiophosphate dioxyphosphate, Oxymolybdenum dibutyl dithiophosphate Oxide, sulfurized oxymolybdenum dibenzyl dithiophosphate, sulfurized oxymolybdenum dihexyl dithiophosphate, sulfurized oxymolybdenum dioctyl dithiophosphate, sulfurized oxymolybdenum didecyl dithiophosphate, sulfurized oxymolybdenum didodecyl dithiophosphate, sulfurized oxymolybdenum di (butylphenyl) dithiophosphate, sulfurized oxy Examples thereof include molybdenum di (nonylphenyl) dithiophosphate.

Further, the phosphoric acid ester or phosphite ester of (1) in the component (C) may be any of mono-, di-, and triesters, and the alcohol residue thereof has 4 to 30 carbon atoms. Alkyl groups having 6 to 30 carbon atoms, such as butyl, octyl, lauryl, stearyl, oleyl groups, etc., such as phenyl groups, and alkyl substituted aryl groups having 7 to 30 carbon atoms, such as methylphenyl, octyl Examples thereof include a phenyl group. Examples of specific compounds include tributyl phosphate, monooleyl phosphate, dioctyl phosphate, dioleyl phosphite,
Examples thereof include diphenyl phosphite and tricresyl phosphate. Examples of these amine salts include stearyl amine salts, oleyl amine salts, and coconut amine salts.

Further, as the hydrocarbon sulfide represented by the general formula of Chemical formula 4 in (2) of the component (C), R ⁵ is a monovalent hydrocarbon group such as an alkyl group or an alkenyl group. Such a linear or branched, saturated or unsaturated aliphatic hydrocarbon group having 2 to 20 carbon atoms, or 6 to 26 carbon atoms
R ⁶ is a divalent hydrocarbon group, for example, a linear or branched saturated or unsaturated aliphatic hydrocarbon group having 2 to 20 carbon atoms, or 6 carbon atoms.
And those represented by the aromatic hydrocarbon groups of ~ 26.

Specific examples of the monovalent hydrocarbon group represented by R ⁵ include ethyl group, propyl group, butyl group, nonyl group, dodecyl group, propenyl group, butenyl group, phenyl group, tolyl group and hexylphenyl. Group, benzyl group and the like. Specific examples of the monovalent hydrocarbon group represented by R ⁶ include ethylene group, propylene group, butylene group and phenylene group.

A typical example of the hydrocarbon sulfide represented by the general formula (4) is represented by sulfided olefin, and R ⁵ -S _x -R ⁵ when x is 2 or more and n is 0. Is a polysulfide compound.

Specific examples of these hydrocarbon sulfides include diisobutyl disulfide, dioctyl polysulfide, ditertiary nonyl polysulfide, ditertiary butyl polysulfide, dibenzyl polysulfide and the like; and olefins such as polyisobutylene and terpenes. Sulfurized olefins sulfurized with sulfides such as sulfur; and reaction products of isobutylene and sulfur, which are presumed to have the chemical formula (7).

[0032]

[Chemical 7]

Further, the sulfurized fats and oils (3) in the component (C) is a reaction product of fats and oils and sulfur, and examples of the fats and oils include lard, beef tallow, whale oil, palm oil, coconut oil, rapeseed oil and the like. Animal and vegetable oils and fats. The reaction product is not a single chemical structure but a mixture of various compounds, and the chemical structure itself is not clear.

If the amount of each of the above-mentioned components (A) and (B) is too small, the synergistic effect of these components (A) and (B) will not sufficiently appear. The corresponding synergistic effect cannot be expected to improve, but rather the cost increases, which is a disadvantage.

The compounding amount of the component (C) added to these may be appropriately selected within the above-mentioned range (1.0 to 10% by weight) depending on the target extreme pressure property. That is,
A gear oil used for industrial gear oils, etc., which does not require the addition of the component (C) if it has a certain degree of extreme pressure property, and is a gear oil used for a differential gear of an automobile, When a considerably high extreme pressure property is required, the component (C) needs to be blended, and the blending degree is often high depending on the use conditions, and extremely high extreme pressure property is required. If you do not need, you can reduce it.

In the gear oil composition of the present invention, in addition to the above-mentioned components (A), (B) and (C), well-known additives that are usually used, such as metal, are used depending on the purpose. A mold detergent, an ashless dispersant, an antiwear agent, a friction modifier, an antioxidant, a corrosion inhibitor, a viscosity index improver, a pour point depressant, an antifoaming agent and the like are added.

Alkaline earth metal sulfonates, alkaline earth metal phenates and the like are used as the above metal type detergents, and alkenyl succinimides, alkenyl succinic acid esters, long chain fatty acids and polyamines are used as the ashless type dispersant. Amides (amino amide type), Zn-DTP and the like as antiwear agents, and friction modifiers,
Fatty acids, organic molybdenum compounds other than the component (B), etc., antioxidants such as Zn-DTP, amine antioxidants, phenolic antioxidants, etc., corrosion inhibitors such as benzotriazole, alkenyl succinate. Acid esters and the like, viscosity index improvers such as polymethacrylate and olefin copolymers, pour point depressants such as polymethacrylate, and defoamers such as
Silicon compounds, ester-based defoaming agents and the like can be mentioned, respectively.

[0039]

【Example】

Examples 1-5, Comparative Examples 1-4 Gear oil compositions of the present invention having the compositions shown in Tables 1-2 (Example 1
5 to 5) and a gear oil composition for comparison of compositions shown in Table 3 (Comparative Examples 1-2) and a commercially available SP-based gear oil (Comparative Examples 3-4).
The following test was conducted on the. Oxidation stability was evaluated by the lubricating oil oxidation stability test method for internal combustion engines (JIS K 251).
According to 4), it was performed at 150 ° C. for 48 hours. For the abrasion resistance test, a shell four-ball abrasion tester was used, and the rotation speed was 1
The test was performed for 30 minutes under the conditions of 800 rpm and a load of 40 kg, and the diameter of the wear mark of the test steel ball was evaluated. The extreme pressure test was conducted with an IAE gear tester at an oil temperature of 110 ° C and a rotation speed of 6
It was evaluated at 000 rpm. The friction reducing effect is obtained by using a Falex Block-on-Ring friction & wear tester according to ASTM D-2981 and an oil temperature of 80 ° C.
The friction coefficient (μ) was measured under the conditions of a rotation speed of 1000 rpm and a load of 100 pounds. The above results are shown in Tables 4-6.

As is clear from Tables 4 to 6, the gear oil compositions of the present invention (Examples 1 to 5) are the comparative gear oil compositions (Comparative Examples 1 and 2) and the commercially available SP type gear oils ( Comparative Example 3
It can be seen that the oxidation stability is extremely good while maintaining the extreme pressure property and the wear resistance equal to or higher than those of (4) to (4).
Further, it can be seen that the gear oil compositions (Examples 1 to 5) of the present invention do not show deterioration in extreme pressure property and wear resistance even when the viscosity is reduced.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

[Table 3]

[0044]

[Table 4]

[0045]

[Table 5]

[0046]

[Table 6]

[0047]

As described above in detail, according to the gear oil composition of the present invention, the mutual interaction between the alkali metal borate hydrate as the component (A) and the organic molybdenum compound as the component (B) is established. By the action (synergistic effect), it is possible to improve both the extreme pressure property, which has heretofore been difficult, and the wear resistance and the oxidation stability, in a well-balanced manner. This can prevent gear troubles for a long time,
Long drainage can contribute to labor saving in maintenance. Further, when the viscosity is lowered, the boundary lubrication region increases at high temperature, but seizure is caused by the synergistic effect of the components (A) and (B) and the wear reduction effect of the organic molybdenum compound of the component (B). It is possible to suppress wear and friction, and to contribute to improvement of fuel efficiency in both reduction of stirring resistance and reduction of friction resistance. Also,
By blending the component (C) in addition to the components (A) and (B), higher extreme pressure can be obtained, and at the same time, abrasion resistance and oxidation stability can be improved.

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Claims (2)

[Claims] 1. A base oil comprising at least one selected from mineral oils and synthetic oils, to which an alkali metal borate hydrate as a component (A) is added in an amount of 0.07 to 1.5% by weight in terms of boron content. %, As a component (B), 0.1 to 10% by weight of at least one organic molybdenum compound represented by the general formula of Chemical formula 1 is contained. [Chemical 1] 2. The gear oil composition according to claim 1, wherein, as the component (C), (1) a phosphoric acid ester, a phosphorous acid ester, an amine salt thereof, or (2) is represented by the general formula: Hydrocarbon sulfide, (3) A gear oil composition comprising 1.0 to 10% by weight of at least one selected from the group consisting of sulfurized fats and oils, which are reaction products of fats and oils and sulfur.