JP2546796B2 - Lubricating oil composition for power transmission - Google Patents

Description

TECHNICAL FIELD The present invention relates to a power transmission lubricating oil composition, and more particularly to a power transmission lubricating oil composition having an excellent traction coefficient and excellent friction characteristics of a wet clutch. .

[Problems to be Solved by Conventional Techniques and Inventions] In recent years, traction drives (friction drive devices by rolling contact) have been adopted as continuously variable transmissions for automobiles, continuously variable transmissions for industry, and the like. As a fluid used for such a traction drive, one having a high traction coefficient and a high power transmission efficiency is required.

Incidentally, the traction drive mechanism often includes a clutch mechanism (wet clutch mechanism) in the same system. Therefore, there is a demand for a lubricating oil having excellent performance as a traction oil and excellent friction characteristics of a wet clutch.
The term "friction characteristics" as used herein refers to the ratio of the coefficient of static friction to the coefficient of dynamic friction, and it is required that this ratio be small and that changes with temperature and time be small.

However, although the conventional traction oil has a high traction coefficient and excellent power transmission efficiency, the friction characteristics of the wet clutch are insufficient, so that the shift shock caused by the clutch operation is large and the riding comfort of an automobile is poor. is there.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above conventional problems and to provide a power transmission lubricating oil composition having excellent friction characteristics of a wet clutch while maintaining the performance required for traction oil. .

[Means for Solving Problems] That is, the present invention relates to (A) a base oil containing a condensed hydrocarbon of a condensed ring and / or a non-condensed ring as a main component,
(B) Alkenyl group-substituted succinic acid ester having 6 to 30 carbon atoms and / or 6 to 30 carbon atoms based on the total amount of the composition
0.05 to 5% by weight of alkyl group-substituted succinate,
(C) 0-5% by weight of polyhydric alcohol fatty acid ester
And (D) zinc dithiophosphate and the general formula [IV] Or general formula [V] (In the general formulas [IV] and [V], R ¹⁷ , R ¹⁸ and R ^{19 each} represent a hydrogen atom, an alkyl group having 4 to 30 carbon atoms, an aryl group or an alkyl-substituted aryl group. , R ¹⁷ , R ¹⁸ and R ¹⁹ may be the same as or different from each other.
The present invention provides a lubricating oil composition for power transmission, which is blended in an amount of -10% by weight.

In the present invention, a base oil containing a condensed ring and / or a non-condensed ring saturated hydrocarbon as a main component is used as the component (A). As such a saturated hydrocarbon, various ones may be mentioned, but a saturated hydrocarbon having a cyclohexyl group and / or a decalyl group, and having 10 to 40 carbon atoms is particularly preferable. Specific examples of the saturated hydrocarbon having a cyclohexyl group and / or a decalyl group include the following.

That is, for example, the expression 2-methyl-2,4-dicyclohexylbutane represented by the formula: 1-decalyl-1-cyclohexylethane represented by the formula: 2-methyl-2,4-dicyclohexylpentane represented by the formula: (In the formula, R ⁷ represents an alkyl group having 10 to 30 carbon atoms). Specifically, isododecylcyclohexane,
Isopentadecyl cyclohexane etc. can be mentioned.

In addition, the condensed ring and / or non-condensed ring saturated hydrocarbon which is the component (A) in the present invention may further include the following.

That is, the expression 1,2-di (dimethylcyclohexyl) propane represented by the formula 2,3-di (methylcyclohexyl) -2- represented by
Methyl butane, formula 1,2-di (methylcyclohexyl) -2-
Methyl propane, formula 2,4-dicyclohexylpentane represented by the formula: Cyclohexylmethyldecalin represented by the formula and 1- (methyldecalyl) -1-cyclohexylethane represented by the formula: and 1- (dimethyldecalyl) -1-cyclohexylethane represented by the formula: 2-decalyl-2-cyclohexylpropane represented by the formula: Cyclohexylmethylperhydrofluorene represented by the formula: 1-perhydrofluorenyl-1-cyclohexylethane represented by the formula: Cyclohexylmethylperhydroacenaphthene represented by the formula: 1,1,2-tricyclohexylethane represented by the formula Bisdecalin represented by 2,4,6-tricyclohexyl-2-methylhexane represented by the formula 2- (2-decalyl) -2,4,6-trimethylnonane represented by the formula: 1,1-didecalylethane represented by the formula Tercyclohexyl represented by 1,1,3-trimethyl-3-cyclohexylhydrindane represented by the formula: 2-methyl-1,2-didecalyl propane and the like can be mentioned, and these can be used alone or in combination of two or more kinds.

The component (A) in the present invention is a base oil containing the above-mentioned condensed ring and / or non-condensed ring saturated hydrocarbon as a main component, and in addition to this, mineral oil, especially naphthenic mineral oil and polybutene at a ratio of 50% or less, It may contain a synthetic oil such as alkylbenzene.

In the present invention, an alkenyl group-substituted succinic acid ester having 6 to 30 carbon atoms and / or an alkyl group substituted succinic acid ester having 6 to 30 carbon atoms is used as the component (B).
The alkenyl group-substituted succinic acid ester (hereinafter referred to as alkenyl succinic acid ester) or the alkyl group-substituted succinic acid ester (hereinafter referred to as alkyl succinic acid ester) is represented by the following general formula [I]. Is.

In the above formula [I], in the alkenyl succinic acid ester, R ⁸ is an alkenyl group having 6 to 30 carbon atoms, and in the alkyl succinic acid ester, R ⁸ is an alkyl group having 6 to 30 carbon atoms.

In the above formula [I], R ⁹ and R ¹⁰ represent hydrogen or an alkyl group having 1 to 20 carbon atoms. Wherein R ⁹ and R ¹⁰ may be the same or different but, R ⁹ and R
Excluded if both of ¹⁰ are hydrogen.

Specific examples of alkenyl succinic acid ester and alkyl succinic acid ester include octadecenyl succinic acid monomethyl ester, octadecenyl succinic acid dimethyl ester, octadecenyl succinic acid monoethyl ester,
Octadecenyl succinic acid diethyl ester, octadecenyl succinic acid monolauryl ester, dodecyl succinic acid monolauryl ester, dodecyl succinic acid dilauryl ester, hexadecyl succinic acid monomethyl ester, hexadecyl succinic acid dimethyl ester, hexadecyl succinic acid Acid monoethyl ester, hexadecyl succinic acid diethyl ester, octadecyl succinic acid monomethyl ester, octadecyl succinic acid dimethyl ester, octadecyl succinic acid monoethyl ester, octadecyl succinic acid diethyl ester, alkenyl succinic acid and propylene of propylene oligomer having an average carbon number of 18 Examples thereof include a reaction product with glycol, a reaction product with polybutenyl succinic acid of polybutene having an average molecular weight of 400, and propylene glycol.

In the present invention, either or both of the alkenyl succinic acid ester and the alkyl succinic acid ester are added as the component (B), but the addition amount varies depending on the properties of the intended lubricating oil composition and cannot be uniquely determined. . But usually 0.05-5.0% by weight, preferably
It is 0.1 to 3.0% by weight. If the addition amount is less than 0.05% by weight, a sufficient effect cannot be obtained, and if it exceeds 5.0% by weight, the oxidation stability is deteriorated, which is not preferable.

Next, in the present invention, a fatty acid ester of a polyhydric alcohol is used as the component (C). Here, examples of the polyhydric alcohol include ethylene glycol, glycerin, trimethylolpropane, pentaesterite, and sorbit, and glycerin is particularly preferable. The fatty acids include those having 8 to 30 carbon atoms, and may be saturated or unsaturated. Specific examples of fatty acids include pelargonic acid,
Lauric acid, palmitic acid, stearic acid, behenic acid,
Examples include undecylenic acid, oleic acid, linoleic acid, and linolenic acid. Examples of more preferable esters include oleic acid monoglyceride, oleic acid diglyceride,
Partial esters of polyhydric alcohols such as stearic acid monoglyceride and stearic acid diglyceride can be mentioned.

The amount of the component (C) added is 0 to 5% by weight, preferably
It is 0.005 to 3% by weight. When further improvement is required for the lubricating oil composition of the present invention, it is necessary to add the component (C). However, if added in excess of 5% by weight,
It is not preferable because the oxidative stability deteriorates.

Further, in the present invention, as the component (D), an antiwear agent composed of zinc dithiophosphate and the phosphoric acid ester represented by the general formula [IV] or the general formula [V] is used.

Zinc dithiophosphate has the general formula [In the formula, R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are the first having 3 to 30 carbon atoms.
A primary alkyl group, a secondary alkyl group having 3 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an alkyl group-substituted aryl group. However, R ¹¹ , R ¹² , R ¹³ and R ¹⁴ may be the same or different. ] Is represented.

There are various zinc dithiophosphates represented by the above general formula [II], from those in which all the substituents of R ^{11 to} R ^{14 in} the formula are the same to those in which they are different from each other. Used as a mixture of two or more kinds. Usually, two or more zinc dithiophosphates having the same substituents for R ^{11 to} R ¹⁴ are mixed and used. However, they can be used alone, or zinc dithiophosphates in which R ^{11 to} R ¹⁴ are different substituents are independently used, or these and zinc dithiophosphates in which R ^{11 to} R ¹⁴ are all the same are appropriately mixed. It is also possible to use. However,
In any case, it is preferable that 1/3 (weight) or more of zinc dithiophosphate having a primary alkyl group having 3 to 30 carbon atoms is present in all zinc dithiophosphates used, particularly 1/2
It is preferable that these exist.

Thus, by using one having 1/3 or more of zinc dithiophosphate having a primary alkyl group having 3 to 30 carbon atoms, relative to the total amount of R ^{11 to} R ¹⁴ in all zinc dithiophosphate, The wear resistance and load bearing capacity are further improved, the fatigue life is extended, and the durability is further improved.

As such a zinc dithiophosphate, a commercially available one may be used, for example, a product of Nippon Lubrizol Co.
Lubrizol 1097 (where R ^{11 to} R ¹⁴ are mainly composed of primary octyl groups) and 1395 (where R ^{11 to} R ¹⁴ are mainly composed of primary butyl groups and amyl groups); Caronite chemistry OLOA 267 (where R ^{11 to} R ¹⁴ are primarily hexyl groups); Nippon Cooper's Hitec E 682 (R ^{11 to} R ^14
14 having a primary hexyl group as a main component); Amoco Chemical's Amoco 198 (R ^{11 to} R ¹⁴ having a primary butyl group and an amyl group as main components), etc., alone or The mixture is appropriately mixed and used, and the substituents R ^{11 to} R ¹⁴ are preferably the first group.
The proportion of zinc dithiophosphate which is a primary alkyl group may be adjusted to 1/3 or more, particularly preferably 1/2 or more.

Specific examples of the phosphoric acid esters include triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, tri (isopropylphenyl) phosphate, butyl acid phosphate, 2-ethylhexyl acid phosphate, lauryl acid phosphate, oleyl acid phosphate, stearyl. Acid phosphate, dibutyl hydrogen phosphite,
Examples thereof include phosphoric acid esters or phosphorous acid esters such as dioctyl hydrogen phosphite, dilauryl hydrogen phosphite, dioleyl hydrogen phosphite, and distearyl hydrogen phosphite.

The component (D) of the present invention as described above is blended in a proportion of 0.1 to 10% by weight, preferably 0.5 to 5% by weight, based on the total amount of the composition. Here, if the blending ratio of the component (D) is less than 0.1% by weight, the abrasion resistance is lowered, which is not preferable.
On the other hand, if it exceeds 10% by weight, corrosion will increase,
It is not preferable because the stability becomes worse.

The lubricating oil composition for power transmission of the present invention has the above (A) to
(D) component, but if necessary, a rust preventive agent,
In addition to antioxidants, pour point depressants, viscosity index improvers, etc., additives such as defoaming agents, oiliness agents, corrosion inhibitors, fatigue life improvers and the like can be added as appropriate.

Here, various rust preventive agents can be mentioned. For example, calcium sulfonate, barium sulfonate, sodium sulfonate, etc., alkyl or alkenyl succinic acid, its derivatives, tri-n-butylamine, n-octylamine, tri-n-octylamine, cyclohexylamine and other alkylamines and 6 carbon atoms. ~ 20 fatty acids, aromatic carboxylic acids, 2 to 20 carbon atoms
The above-mentioned alkylamine salts or ammonium salts of carboxylic acids such as dibasic acids, and condensates of the above-mentioned various carboxylic acids with amines. Among these, it is preferable to use calcium sulfonate or barium sulfonate.

As an antioxidant, 2,6-ditertiary butyl-
Examples thereof include phenolic antioxidants such as p-cresol and 4,4′-methylenebis (2,6-ditertiarybutylphenol) and amine antioxidants such as dioctyldiphenylamine.

Further, as the pour point depressant or the viscosity index improver, polymethacrylate may be mentioned, and those having a number average molecular weight of 10,000 to 100,000 are particularly preferable. In addition, olefin copolymers such as engine / propylene copolymers and styrene / propylene copolymers can be used.

[Examples] Examples of the present invention will be shown below, but the present invention is not limited thereto unless the scope of the present invention is exceeded.

Preparation example (preparation of base oil) 1000 g of tetralin and concentrated sulfuric acid 3 in a 3 l glass flask.
00 g was put and the temperature in the flask was cooled to 0 ° C. in an ice bath. Next, 400 g of styrene was slowly added dropwise to this over 3 hours while stirring, and the reaction was completed by stirring for 1 hour. After that, stop stirring and let stand to separate the oil layer,
The oil layer was washed three times with 500 cc of 1N aqueous sodium hydroxide solution and 500 cc of saturated saline solution, respectively, and then dried over anhydrous sodium sulfate. Subsequently, unreacted tetralin is distilled off by distillation, and then vacuum distillation is performed to obtain a boiling point of 135
About 148 ° C / 0.17mmHg fraction 750g was obtained. As a result of analyzing this fraction, it was confirmed to be a mixture of 1- (1-tetralyl) -1-phenylethane and 1- (2-tetralyl) -1-phenylethane.

Next, put 500 cc of the above fraction into the 1 autoclave,
Further, 50 g of 5% ruthenium-carbon catalyst was added, and hydrogenation treatment was carried out for 4 hours under the conditions of hydrogen pressure of 20 kg / cm ² and reaction temperature of 120 ° C. After cooling, the reaction solution was passed through to separate the catalyst. After stripping the light fraction from the liquid,
It was confirmed by analysis that the hydrogenation rate was 99.9% or more, and that this was a mixture of 1- (1-decalyl) -1-cyclohexylethane and 1- (2-decalyl) -1-cyclohexylethane. . The specific gravity of the obtained mixture was 0.94 (15/4 ° C), the kinematic viscosity was 4.9 cSt (100 ° C), the refractive index ▲ n ²⁰ _D ▼ was 1.5048, and the cis ratio was 88.
%.

Examples 1 to 3 and Comparative Example 1 A lubricating oil composition was prepared by adding the components shown in Table 1 to the base oil (component A) obtained in Preparation Example at a predetermined ratio. Various tests were conducted. The results are shown in Table 1. The test method is as follows.

Test Method SAE No. 2 Friction Test Using a SAE No. 2 tester manufactured by Greening Company (USA), the friction characteristics were evaluated under the following experimental conditions.

[Experimental conditions] Disc: Paper disc for domestic automatic transmission (2
Plates: Steel plates for domestic automatic transmission (4) Motor rotation speed: 3000 rpm Piston pressing pressure: 3 kg / cm ² Oil temperature: 110 ° C The dynamic friction coefficient at a rotation speed of 1200 rpm under experimental conditions of μ ₁₂₀₀ , measured as the static friction coefficient mu ₀ when stopping, the μ ₀ / μ ₁₂₀₀ issued a total. However, the value after 500 cycles is shown.

Traction coefficient: 2 Cylinder type rolling friction tester was used. That is,
A cylinder A having a curvature (diameter 52 mm, radius of curvature 10 mm) and a cylinder B having a flat surface (diameter 52 mm) are brought into contact with each other at 7000 gf, and the cylinder A slips at a constant speed (1500 rpm) and the cylinder B is accelerated from 1500 rpm. The traction coefficient generated between both cylinders at a rate of 5% was measured to determine the traction coefficient.

Here, the material of the two cylinders is bearing steel SUJ-2, the surface is buffed with alumina (0.03μ), the surface roughness is R _max 0.1μ or less, and the Hertz contact pressure is 112kgf.
It was / mm ² . The sample oil was measured while being kept at 100 ° C by controlling the temperature.

Comparative Example 2 Commercially available traction drive lubricating oil (main component: α-
Various tests were conducted on a dimer of methylstyrene). The results are shown in Table 1.

[Effect of the Invention] The lubricating oil composition of the present invention has a high traction coefficient and a high power transmission rate.

Moreover, the lubricating oil composition of the present invention has excellent friction characteristics of a wet clutch. That is, the ratio between the static friction coefficient and the dynamic friction coefficient is small.

Therefore, the lubricating oil composition of the present invention can be effectively used as a lubricating oil for a traction drive having a wet clutch mechanism.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C10M 137: 04 139: 00) C10N 30:06 40:04 (56) Reference JP-A-62- 10194 (JP, A) JP-A-59-25890 (JP, A) JP-B-49-45769 (JP, B1) JP-B-47-49284 (JP, B1) PETROTECH, 7 [5] (1984) P. 426-429

Claims (1)

(57) [Claims] 1. A base oil comprising (A) a saturated and / or non-condensed ring saturated hydrocarbon as a main component, and (B) an alkenyl group-substituted amber having 6 to 30 carbon atoms based on the total amount of the composition. An acid ester and / or an alkyl group-substituted succinic acid ester having 6 to 30 carbon atoms in an amount of 0.05 to 5% by weight, (C) a polyhydric alcohol fatty acid ester in an amount of 0 to 5% by weight, and (D) zinc dithiophosphate; (IV) Or general formula [V] (In the general formulas [IV] and [V], R ¹⁷ , R ¹⁸ and R ^{19 each} represent a hydrogen atom, an alkyl group having 4 to 30 carbon atoms, an aryl group or an alkyl-substituted aryl group. , R ¹⁷ , R ¹⁸ and R ¹⁹ may be the same as or different from each other.
A lubricating oil composition for power transmission, which is blended in an amount of 10% by weight.