JP2017101151A - Lubricant composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricant composition satisfying performance required for a non-stage transmission oil corresponding to fuel saving (low viscosity) and capable of suppressing belt noise specific to the non-stage transmission generated without being caused by high and low of intermetallic friction.SOLUTION: There is provided a lubricant composition containing a base oil, (A) thiadiazole of 0.3 mass% or more based on total amount of the composition, (B) a sulfur additive containing phosphor of 0.05 mass% or more based on total amount of the composition and (C) a boron-containing ashless dispersant of 50 mass.ppm in terms of boron element based on total amount of the composition and having sulfur content of the composition of 0.3 mass% or more in terms of sulfur element and phosphorus content of 0.2 mass% or less in terms of phosphor element.SELECTED DRAWING: None

Description

  The present invention relates to a lubricating oil composition, preferably a lubricating oil composition suitable for a continuously variable transmission, particularly a metal belt type continuously variable transmission.

Recent automatic transmissions and continuously variable transmissions are desired to be lighter and smaller, and with the increase in the output of the combined engine, improvement in power transmission capability is being pursued. The purpose of reducing the weight and size is to improve the fuel consumption of a vehicle to be mounted.
In particular, in the case of a metal belt type continuously variable transmission, if the friction coefficient between the belt and the pulley can be improved, the size can be reduced, so that the lubricating oil used there has a characteristic of maintaining a high coefficient of friction between metals. Things are preferred.
Furthermore, the fuel consumption reduction by these lubricating oil is also calculated | required. Specifically, it contributes to the improvement of fuel consumption by reducing the agitation resistance by lowering the viscosity of the lubricating oil and reducing the power loss by reducing the viscous resistance during idling of the wet clutch pack or at the time of fluid lubrication.

  As conventional transmission fluids, friction modifiers, metal detergents, ashless dispersants, anti-wear agents are used to maintain the friction characteristics of the lock-up clutch and maintain the initial anti-shudder performance for a long period of time. Etc. have been proposed (for example, see Patent Documents 1 to 7).

  For example, Patent Document 1 includes a specific calcium salicylate and SP-based extreme pressure agent, a specific amount of a specific succinimide and a boron-containing ashless dispersant, excellent anti-shudder life, and excellent fatigue life. A lubricating oil composition for a transmission having performance has a high intermetal friction coefficient, in which an organic acid metal salt having a specific structure, an antiwear agent, and a boron-containing succinimide are blended as essential components in Patent Document 2. Is a lubricant composition for continuously variable transmissions that achieves both anti-shudder properties and slip control mechanisms. Patent Document 3 contains calcium salicylate, phosphorus-based antiwear agent, friction modifier, and dispersion type viscosity index improver. A lubricating oil composition for a continuously variable transmission that is compatible with a high coefficient of friction between metals and anti-shudder for a slip control mechanism and can be used for a long period of time is disclosed in Patent Document 4. Is a lubricating oil composition with excellent anti-shudder performance and long anti-shudder life, comprising a dithiocarbamate compound, a condensate of a branched chain fatty acid having 8 to 30 carbon atoms and an amine, and an amine-based antioxidant. In Patent Document 5, the anti-shudder life performance of the slip lockup device, in which calcium sulfonate and phosphites, and a sarcosine derivative or a reaction product of a carboxylic acid and an amine are blended, is included. An automatic transmission oil composition having a long life performance with respect to a belt-type CVT device is disclosed in Patent Document 6, which includes a specific amount of a specific alkaline earth metal sulfonate. It has excellent oxidation stability for use as well as anti-shudder performance and long-term use. Automatic transmission fluid composition having long-term durability is disclosed to be. Further, Patent Document 7 discloses an automatic transmission oil having excellent anti-shudder properties and a constant transmission torque capacity, which includes specific amounts of calcium salicylate and magnesium salicylate, specific friction modifiers, and boric acid-modified succinimide. ing.

JP 2003-113391 A JP 2001-323292 A JP 2000-355695 A Japanese Patent Application Laid-Open No. 11-50077 Japanese Patent Laid-Open No. 10-306292 Japanese Patent Laid-Open No. 10-25487 JP 2000-63869 A

  However, when the viscosity is lowered, the oil film in the lubrication part becomes thin, and wear and seizure are likely to occur. That is, the extreme pressure property and the wear resistance decrease due to the decrease in the oil film thickness as the contradictory performance of lowering the viscosity. In the continuously variable transmission oil, it is necessary to improve the belt capacity (coefficient of friction between metals) in order to improve the transmission efficiency, but this also leads to a decrease in extreme pressure and wear resistance.

  As a result of intensive research on the above problems, the present inventors have found that a lubricating oil containing a specific amount of thiadiazole and a phosphorus-containing sulfur-based additive and having a sulfur and phosphorus content of the composition in a specific range is continuously variable. The machine's belt capacity, that is, the high friction coefficient between metals, extreme pressure and wear resistance, and by adding a specific amount of boron compound, the metal / metal dynamic friction coefficient can be set high, and the metal generated during rapid acceleration. The present inventors have found that it is suitable for suppressing the noise of the belt and have completed the present invention.

  That is, the present invention comprises a base oil, (A) thiadiazole, 0.3% by mass or more based on the total amount of the composition, (B) a sulfur-based additive containing phosphorus, 0.05% by mass or more, based on the total amount of the composition, And (C) a boron-containing ashless dispersant based on the total amount of the composition, containing 50 mass ppm or more in terms of boron element, the sulfur content of the composition being 0.3 mass% or more in terms of sulfur element, and the phosphorus content being elemental phosphorus It is a lubricating oil composition characterized by being 0.2% by mass or less in terms of conversion.

  The lubricating oil composition of the present invention satisfies the performance required for continuously variable transmission oils corresponding to fuel saving (low viscosity), and at the same time, is generated without causing high or low coefficient of friction between metals. Specific belt noise can be suppressed.

  Hereinafter, the present invention will be described in detail.

  The lubricating oil composition of the present invention contains a mineral base oil and / or a synthetic base oil as a base oil.

  As mineral base oil, solvent degreasing, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrodewaxing of lubricating oil fractions obtained by atmospheric and vacuum distillation of crude oil Examples thereof include paraffinic or naphthenic mineral oil base oils obtained by applying one or two or more kinds of purification means such as sulfuric acid washing and clay treatment as appropriate.

  Synthetic oils include, for example, poly α-olefins (ethylene-propylene copolymer, polybutene, 1-octene oligomer, 1-decene oligomer, and hydrides thereof), alkylbenzene, alkylnaphthalene, monoester (butyl stearate). Octyl laurate), diester (ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-2-ethylhexyl sepacate, etc.), polyester (trimellitic acid ester, etc.), polyol ester (tri Methylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol-2-ethylhexanoate, pentaerythritol pelargonate), polyoxyalkylene glycol Obtained from synthetic waxes such as polyphenyl ether, dialkyl diphenyl ether, phosphate esters (tricresyl phosphate, etc.), fluorine-containing compounds (perfluoropolyether, fluorinated polyolefins, etc.), silicone oil, FT reaction and / or petroleum refining process High-performance hydrocarbon base oil obtained by isomerization and hydrogenation of the resulting wax (preferably slack wax obtained in the solvent dewaxing step), and obtained by hydrogenating naturally-occurring unsaturated hydrocarbons such as terpenes Examples include hydrocarbon base oils.

  As the base oil according to the present invention, the above base oils may be used alone or in combination of two or more.

The kinematic viscosity of the lubricating base oil used in the present invention is not particularly limited, but the kinematic viscosity at 100 ° C. is preferably 1.5 to 10 mm ² / s, more preferably 2.0 to 7.0 mm ² /. It is desirable to adjust to s, particularly preferably 2.5 to 4.5 mm ² / s. When the kinematic viscosity at 100 ° C. of the lubricating base oil exceeds 10 mm ² / s, the low-temperature viscosity characteristics deteriorate, whereas when the kinematic viscosity is less than 1.5 mm ² / s, the oil film at the lubrication point Since the formation is insufficient, the lubricity is inferior, and the evaporation loss of the lubricating base oil is increased, which is not preferable.

  The viscosity index of the lubricating base oil used is not particularly limited, but is preferably 100 or more, more preferably 120 or more, still more preferably 130 or more, particularly preferably 135 or more, and usually 200 or less. , Preferably 180 or less, more preferably 160 or less. By setting the viscosity index to 100 or more, it is possible to obtain a composition exhibiting favorable viscosity characteristics from a low temperature to a high temperature. On the other hand, if the viscosity index is too high, the viscosity at low temperatures tends to increase, which is not preferable.

  Further, the sulfur content of the lubricating base oil used in the present invention is not particularly limited, but is preferably 0.1% by mass or less, more preferably 0.05% by mass or less, and 0.01% by mass. % Or less, more preferably 0.005% by mass or less, and most preferably substantially 0. A composition superior in oxidation stability can be obtained by reducing the sulfur content of the lubricating base oil.

  Since the base oil used in the present invention is preferably a base material containing no sulfur, a raw material containing 50% by mass or more of a wax such as hydrocracked mineral base oil, petroleum-based or Fischer-Tropsch synthetic oil is isomerized. Particularly preferred are wax isomerized base oils and synthetic oil base oils such as poly α-olefins.

  The lubricating oil composition of the present invention contains thiadiazole as the component (A).

  Examples of the thiadiazole compound include 1,3,4-thiadiazole represented by the following general formula (1), 1,2,4-thiadiazole compound represented by the following general formula (2), and the following general formula (3). 1,4,5-thiadiazole compound represented by the following.

In formulas (1) to (3), R ^{1 to} R ⁶ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, and each of a, b, c, d, e, and f may be the same or different and each represents an integer of 0 to 8.

  Examples of the hydrocarbon group include an alkyl group, a cycloalkyl group, an aryl group, an alkylcycloalkyl group, an alkylaryl group, a cycloalkylalkyl group, and an arylalkyl group. These include all isomers and structural isomers if there are isomers and structural isomers.

  More specifically, the hydrocarbon group having 1 to 20 carbon atoms is methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group. , Dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group; cyclopentyl group, cyclohexyl group, cycloheptyl group; phenyl group, naphthyl group;

  Specific examples of such thiadiazole compounds include 2,5-bis (n-hexyldithio) -1,3,4-thiadiazole, 2,5-bis (n-octyldithio) -1,3,4-thiadiazole. 2,5-bis (n-nonyldithio) -1,3,4-thiadiazole, 2,5-bis (1,1,3,3-tetramethylbutyldithio) -1,3,4-thiadiazole, 3, 5-bis (n-hexyldithio) -1,2,4-thiadiazole, 3,5-bis (n-octyldithio) -1,2,4-thiadiazole, 3,5-bis (n-nonyldithio) -1 , 2,4-thiadiazole, 3,5-bis (1,1,3,3-tetramethylbutyldithio) -1,2,4-thiadiazole, 4,5-bis (n-hexyldithio) -1,2 , 3-thiadiazole, 4 5-bis (n-octyldithio) -1,2,3-thiadiazole, 4,5-bis (n-nonyldithio) -1,2,3-thiadiazole, 4,5-bis (1,1,3,3) Preferred examples include -tetramethylbutyldithio) -1,2,3-thiadiazole and mixtures thereof.

  The content of the component (A) is 0.3% by mass or more, preferably 0.5% by mass or more, more preferably 0.7% by mass or more, and further preferably 1% by mass or more, based on the total amount of the composition. . Moreover, it is preferable that it is 5 mass% or less, and 3 mass% or less is more preferable. If it is less than 0.3% by mass, the effect of improving the coefficient of friction between metals is not sufficient, and if it exceeds 5% by mass, problems such as clogging of the wet clutch occur.

  The lubricating oil of the present invention contains a sulfur-based additive containing phosphorus as the component (B).

The sulfur-based additive containing phosphorus is not particularly limited as long as it is a sulfur-based compound that is sufficiently dissolved in the lubricating base oil and contains phosphorus in the molecule.
Examples of such compounds include thiophosphoric acid, thiophosphoric acid esters, thiophosphorous acid, thiophosphorous acid esters and salts thereof, zinc dithiophosphate, molybdenum dithiophosphate, and the like.

  Among these compounds, thiophosphates are preferable, and thiophosphates having a carboxy group at the terminal represented by the following general formula (4) are particularly preferable.

In formula (4), R ₁ is a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, R ₂ is a hydrocarbon group having 1 to 20 carbon atoms, and R ₃ is a divalent hydrocarbon group having 1 to 8 carbon atoms. Indicates.

Number of carbon atoms in the hydrocarbon group of R ₁ and _{R 2} are 1 to 20, preferably 1-12, more preferably 1-8.

Examples of the hydrocarbon group for R ₁ and R ₂ include an alkyl group, a cycloalkyl group, an alkylcycloalkyl group, an aryl group, and an alkylaryl group. More specifically, n-butyl group, isobutyl group, tert-butyl group, cyclopentyl group, cyclohexyl group, methylcyclopentyl group, phenyl group, benzyl group, tolyl group (cresyl group), xylenyl group and the like can be mentioned. The hydrocarbon group may be saturated or unsaturated, and may be linear or branched. Among these, a saturated hydrocarbon group is preferable and an alkyl group is particularly preferable.

The carbon number of the divalent hydrocarbon group of R ₃ is 1 to 8, preferably 2 to 6, and more preferably 2 to 4.
Examples of the hydrocarbon group for R ₃ include an alkylene group, a cycloalkylene group, and an alkylcycloalkylene group. More specific examples include a methylene group and an ethylene group. The hydrocarbon group may be saturated or unsaturated, and may be linear or branched. Among these, a saturated hydrocarbon group is preferable, and an alkylene group is particularly preferable.

  (B) Content of a component is 0.05 mass% or more on a composition whole quantity basis, 0.2 mass% or more is preferable and 0.5 mass% or more is more preferable. Moreover, it is preferable that it is 5 mass% or less, 3 mass% or less is more preferable, 2 mass% or less is more preferable, and 1 mass% or less is especially preferable. If it is less than 0.05% by mass, the seizure prevention performance of the gear is insufficient, and if it exceeds 5% by mass, the judder prevention performance of the wet clutch is adversely affected.

  The lubricating oil of the present invention contains a boron-containing ashless dispersant as the component (C).

  (C) Examples of the boron-containing ashless dispersant include modified products obtained by modifying an ashless dispersant with a boron compound.

Examples of the ashless dispersant include nitrogen-containing compounds or derivatives thereof having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule.
The alkyl group or alkenyl group may be linear or branched, but preferred are olefin oligomers such as propylene, 1-butene, isobutylene, α-olefins derived from ethylene, and ethylene and propylene. Examples include branched alkyl groups and branched alkenyl groups derived from co-oligomers.
The number of carbon atoms of the alkyl group or alkenyl group is arbitrary, but it is preferably 40 to 400, more preferably 60 to 350. When the carbon number of the alkyl group or alkenyl group is less than 40, the solubility of the compound in the lubricating base oil may be reduced. On the other hand, when the carbon number exceeds 400, the low temperature fluidity of the lubricating oil composition may be low. Each of them is not preferable because it may deteriorate.

As the above-mentioned nitrogen-containing compound or derivative thereof, more specific examples include:
(A) Succinimide having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule, or a derivative thereof,
(B) benzylamine having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule, or a derivative thereof,
(C) Polyamine having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule, or a derivative thereof.

  Examples of the succinimide of the group (a) include compounds represented by the following general formula (5) or (6).

In the general formula (5), R ¹ represents an alkyl group or alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350, and p represents an integer of 1 to 5, preferably 2 to 4.
In the general formula (6), R ² and R ³ individually represent an alkyl group or an alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350, and q is 0 to 4, preferably 1 to 3. Indicates an integer.

  As the succinimide, a so-called monotype succinimide such as the general formula (5) in which succinic anhydride is added to one end of the polyamine during imidation, and a general formula in which succinic anhydride is added to both ends of the polyamine are used. There are so-called bis-type succinimides such as (6), but in the present invention, both monotype and bis-type succinimides modified with boron compounds can be used, A mixture of a modified product and a bis-type modified product may be used.

Examples of the benzylamine of the group (b) include compounds represented by the general formula (7).

In the general formula (7), R ⁴ represents an alkyl group or alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms, and r represents an integer of 1 to 5, preferably 2 to 4.

  This benzylamine can be produced by any method. For example, a polyolefin such as propylene oligomer, polybutene, ethylene-α-olefin copolymer is reacted with phenol to form alkylphenol, and then polyamine such as formaldehyde and diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, etc. Can be reacted by Mannich reaction to obtain benzylamine represented by the general formula (7).

Examples of the polyamine of the group (c) include compounds represented by the general formula (8).

In the general formula (8), R ⁵ represents an alkyl group or alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms, and s represents an integer of 1 to 5, preferably 2 to 4.

  This polyamine can also be produced by an arbitrary method. For example, after chlorinating a polyolefin such as a propylene oligomer, polybutene, or an ethylene-α-olefin copolymer, ammonia, ethylenediamine, diethylenetriamine, triethylenetetramine, tetra A polyamine represented by the general formula (8) can be obtained by reacting a polyamine such as ethylenepentamine or pentaethylenehexamine.

  The derivatives of nitrogen-containing compounds include those having 2 to 30 carbon atoms such as monocarboxylic acids having 2 to 30 carbon atoms (fatty acids, etc.), oxalic acid, phthalic acid, trimellitic acid, and pyromellitic acid. The above-mentioned polycarboxylic acid is allowed to act to neutralize or partially amid the remaining amino group and / or imino group, so that a sulfur compound acts on a so-called carboxylic acid-modified compound or a nitrogen-containing compound as described above. A modified sulfur-modified compound.

  The boron compound and the modification method with the boron compound are not limited at all, and any compound and method can be adopted. As an example, a boron compound such as boric acid, borate or boric acid ester is allowed to act on the above nitrogen-containing compounds or derivatives thereof, and amino groups remaining in the nitrogen-containing compounds or derivatives thereof and / or Alternatively, there is a method in which a part or all of the imino group is neutralized or amidated.

  Here, boric acid includes orthoboric acid, metaboric acid, tetraboric acid and the like. The borate includes an alkali metal salt, an alkaline earth metal salt, or an ammonium salt of boric acid, and more specifically, for example, lithium metaborate, lithium tetraborate, lithium pentaborate, persulfate. Lithium borate such as lithium borate; sodium borate such as sodium metaborate, sodium diborate, sodium tetraborate, sodium pentaborate, sodium hexaborate, sodium octaborate; potassium metaborate, tetraborate Potassium borates such as potassium, potassium pentaborate, potassium hexaborate and potassium octaborate; boron such as calcium metaborate, calcium diborate, tricalcium tetraborate, pentacalcium tetraborate and calcium hexaborate Acid calcium; magnesium metaborate, magnesium diborate, trimagnesium tetraborate, pentatetraborate Magnesium, magnesium borate and magnesium hexaborate acid; and ammonium metaborate, ammonium tetraborate, ammonium pentaborate, ammonium borate and ammonium eight borate. Examples of the boric acid ester include esters of boric acid and preferably an alkyl alcohol having 1 to 6 carbon atoms. More specifically, for example, monomethyl borate, dimethyl borate, trimethyl borate, boric acid. Examples include monoethyl, diethyl borate, triethyl borate, monopropyl borate, dipropyl borate, tripropyl borate, monobutyl borate, dibutyl borate, tributyl borate and the like.

  (C) The content of the boron-containing ashless dispersant is 50 mass ppm or more, preferably 100 mass ppm or more, and more preferably 300 mass ppm or more, in terms of the total amount of the composition, in terms of boron element. Moreover, it is preferable that it is 1500 mass ppm or less, and 1000 mass ppm or less is more preferable.

  The lubricating oil of the present invention preferably contains a boron-containing compound other than the above-described (C) boron-containing ashless dispersant as the component (D).

  Examples of boron-containing compounds other than the boron-containing ashless dispersant include (D-1) boric acid esters, (D-2) alkali metal borates or hydrates thereof. Other examples include metal detergents containing a boric acid metal salt. In the present invention, the compound is more preferable.

(D-1) Boric acid esters include esters of boric acid and preferably alkyl alcohols such as monoalkyl borate, dialkyl borate, and trialkyl borate.
Examples of the alkyl group include alkyl groups having 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms. Specifically, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group. Group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, and other alkyl groups (these alkyl groups may be linear or branched) Is mentioned.

(D-2) Examples of the alkali metal borate or hydrate thereof include KB ₃ O ₅ .nH ₂ O and NaB ₃ O ₅ .nH ₂ O (n is 0 to 3, preferably 0 to 1). An example of which is potassium borate or a hydrate thereof or sodium borate or a hydrate represented by a composition formula such as an integer).
These alkali metal borates or hydrates thereof, for example, boric acid and hydroxide so that the atomic ratio of boron to alkali metal (boron / alkali metal) is in the range of 2.0 to 4.5. Dissolve potassium or sodium hydroxide in water and disperse this solution in an oily solution containing neutral alkaline earth metal sulfonate or succinimide-based ashless dispersant and react to obtain a fine particle dispersion. be able to.

  As a commercial item of alkali metal borate hydrate, for example, potassium borate hydrate dispersion OLOA 9750 (boron concentration 6.8% by weight) sold from Oronite Japan KK, or potassium borate hydrate Examples thereof include an object dispersion liquid OLOA 312 (boron concentration of 6.9% by weight).

When the component (D) is contained, the content is preferably 10 ppm by mass or more, more preferably 50 ppm by mass or more, and further preferably 100 ppm by mass or more in terms of the total amount of the composition and in terms of boron element. Moreover, 1000 mass ppm or less is preferable, and 500 mass ppm or less is more preferable.
In addition, the total content of the component (C) and the component (D) is 50 mass ppm or more, preferably 100 mass ppm or more, and more preferably 300 mass ppm or more, in terms of the total amount of the composition and in terms of boron element. Moreover, it is preferable that it is 1500 mass ppm or less, and 1000 mass ppm or less is more preferable.

  The lubricating oil composition of the present invention preferably contains at least one of a metallic detergent, a viscosity index improver, and a friction modifier.

  As the metal detergent, for example, alkali metal or alkaline earth metal sulfonates, phenates, salicylates, naphthenates and the like can be used alone or in combination of two or more. Examples of the alkali metal include sodium and potassium, and examples of the alkaline earth metal include calcium and magnesium. In addition, calcium or magnesium sulfonates, phenates, and salicylates are preferably used as specific metal detergents. Of these, calcium sulfonate is preferable.

  The total base number of the metal detergent is preferably 0 to 600 mgKOH / g, more preferably 200 mgKOH / g or more, further preferably 300 mgKOH / g or more, and particularly preferably 400 mgKOH / g or more. Moreover, Preferably it is 600 mgKOH / g or less. Above 600 mg KOH / g, the stability of the composition is inhibited.

  The content of the metallic detergent is preferably 0.001% by mass or more and 0.01% by mass or more in terms of alkali metal or alkaline earth metal element based on the total amount of the lubricating oil composition. More preferably, it is more preferably 0.1% by mass or more. Moreover, it is preferable that it is 2 mass% or less, and it is more preferable that it is 0.5 mass% or less. If it is less than 0.001% by mass, the noise prevention performance is not sufficient, and if it exceeds 2% by mass, the friction coefficient between metals decreases.

  As the viscosity index improver, for example, a so-called non-dispersion type viscosity index improver such as a copolymer of one or more monomers selected from various methacrylic esters or a hydrogenated product thereof, or further a nitrogen compound is included. Examples include so-called dispersed viscosity index improvers obtained by copolymerizing various methacrylic esters. Specific examples of the other viscosity index improvers include non-dispersed or dispersed ethylene-α-olefin copolymers (examples of α-olefin include propylene, 1-butene, 1-pentene, etc.) and hydrogen thereof. Compound, polyisobutylene and hydrogenated product thereof, styrene-diene hydrogenated copolymer, styrene-maleic anhydride copolymer and polyalkylstyrene.

  The molecular weight of the viscosity index improver is preferably selected in consideration of shear stability. Specifically, the average molecular weight of the viscosity index improver is, for example, in the case of dispersed and non-dispersed polymethacrylates having a weight average molecular weight of 5,000 to 150,000, preferably 5,000 to 35,000. However, in the case of polyisobutylene or a hydride thereof, a weight average molecular weight of 800 to 5,000, preferably 1,000 to 4,000 is a weight in the case of an ethylene-α-olefin copolymer or a hydride thereof. An average molecular weight of 800 to 150,000, preferably 3,000 to 12,000 is desirable.

  In the present invention, the weight average molecular weight means that two columns of GHSHR-M (7.8 mm ID × 30 cm) manufactured by Tosoh Corporation are used in series in a 150-C ALC / GPC apparatus manufactured by Waters, and tetrahydrofuran is used as a solvent. The weight average molecular weight in terms of standard polystyrene measured using a differential refractometer (RI) detector under the conditions of a temperature of 23 ° C., a flow rate of 1 mL / min, a sample concentration of 1% by mass, and a sample injection amount of 75 μL.

  In the present invention, one or two or more compounds arbitrarily selected from these viscosity index improvers can be contained in any amount, but the content thereof is usually a lubricating oil composition. It is desirable that it is 0.1-40 mass% on an object basis.

  Examples of friction modifiers include ashless friction modifiers. Examples of the ashless friction modifier include compounds having 6 to 50 carbon atoms and having at least one heteroatom selected from an oxygen atom and a nitrogen atom in the molecule. As a further specific example of the ashless friction modifier, at least one alkyl group or alkenyl group having 6 to 30 carbon atoms, particularly a linear or branched alkyl group or alkenyl group having 6 to 30 carbon atoms in the molecule. Examples thereof include amine compounds, fatty acid esters, fatty acid amides, fatty acids, aliphatic alcohols, aliphatic ethers, urea compounds, and hydrazide compounds.

  Among these, an aliphatic amide compound is preferable, and an aliphatic amide compound represented by the following general formula (9) or (10) is particularly preferable.

In the general formula (9), R ₁ is an alkyl group or alkenyl group having 10 to 30 carbon atoms, and is a linear group or a linear group having one methyl group as a substituent. R ₂ and R ₃ each independently represent hydrogen or an alkyl group having 1 to 3 carbon atoms, and particularly preferably hydrogen. R ₄ is an alkylene group having 1 to ₄ carbon atoms, and an alkylene group having 2 carbon atoms is particularly preferable. R ₅ and R ₆ each independently represent hydrogen or an alkyl group having 1 to 3 carbon atoms, with hydrogen being particularly preferred. R ₇ is hydrogen or an alkyl group or alkenyl group having 1 to 30 carbon atoms, and is preferably a linear alkyl group or alkenyl group having 10 to 30 carbon atoms. K is 0-6, preferably 1-4, m is 0-2, n, p and r each represents an integer of 0-1.

R ₁ and R ₇ each have 10 or more carbon atoms, preferably 12 or more, more preferably 16 or more, and still more preferably 18 or more. On the other hand, the carbon number of R ₁ and R ₇ is 30 or less, preferably 26 or less, and more preferably 24 or less. R ₁ and R ₇ are preferably linear alkyl groups or alkenyl groups, but more preferably linear alkyl groups or alkenyl groups having a methyl group at the α-position of the carbonyl group. R ₁ and R ₇ are preferably the same as each other.
By making the carbon number of R ₁ and R ₇ 10 or more, the belt noise prevention property can be improved. On the other hand, if the number of carbon atoms exceeds 30, the viscosity characteristics at low temperatures of the composition deteriorate, which is not preferable.

  k is preferably 2 or more, and preferably 4 or less. m is preferably 0 or 1, and most preferably 0. Further, p is preferably 1, and r is preferably 0. By doing so, a high belt noise prevention property can be exhibited.

  The aliphatic amide compound represented by the general formula (9) is preferably a fatty acid diamide, and particularly preferably a fatty acid polyamine diamide (for example, polyalkylene polyamine diisostearic acid amide).

In the general formula (10), R ₁ and R ₂ are each independently an alkyl group or an alkenyl group having 10 to 30 carbon atoms, and are a linear group or a linear group having one methyl group as a substituent. m represents an integer of 3 to 30. X individually represents hydrogen, R ₃ —CO—, or R ₄ —CO—NH— (CH ₂ ) _n —. Here, R ₃ and R ₄ are each independently an alkyl group or alkenyl group having 10 to 30 carbon atoms, and n is an integer of 1 to 3.

R ₁ and R ₂ each have 10 or more carbon atoms, preferably 12 or more, more preferably 14 or more, and still more preferably 16 or more. On the other hand, the carbon number of R ₁ and R ₂ is 30 or less, preferably 26 or less, and more preferably 24 or less. R ₁ and R ₂ are preferably a linear alkyl group or an alkenyl group, but more preferably a linear alkyl group or alkenyl group having a methyl group at the α-position of the carbonyl group.
By making the carbon number of R ₁ and R ₂ 10 or more, the belt noise prevention property can be improved. On the other hand, if the number of carbon atoms exceeds 30, the viscosity characteristics at low temperatures of the composition deteriorate, which is not preferable.

  m is an integer of 3 to 30, preferably 3 to 20, and more preferably 3 to 10. By doing so, a high belt noise prevention property can be exhibited.

X represents a hydrogen atom, R ₃ —CO—, or R ₄ —CO—NH— (CH ₂ ) _n —. Here, R ₃ and R ₄ are each independently an alkyl group or an alkenyl group, and the carbon number thereof is 10 to 30, preferably 12 to 26, more preferably 14 to 24, and still more preferably 16 to 22. N is an integer of 1 to 3, preferably 2.

X in the structural unit —NX— (CH ₂ ) ₂ — in the formula (10) may be the same as or different from each other. Of the m structural units, at least one X is preferably R ₃ —CO— or R ₄ —CO—NH— (CH ₂ ) _n —.

When the compound includes both R ₃ and R ₄ or includes a plurality of R ₃ or R ₄ , these R ₃ and R ₄ are a plurality of R _{3 s} , a plurality of R _{4 s} , a plurality of R _{4 s} , or a combination of R ₃ and R ₄ . In any case, they may be the same or different.

  The content of the friction modifier is preferably 0.5% by mass or more, more preferably 1% by mass or more, and further preferably 1.2% by mass or more based on the total amount of the composition. On the other hand, it is preferably 3% by mass or less, more preferably 2% by mass or less, and further preferably 1.5% by mass or less. If it is less than 0.5% by mass, the effect of preventing noise is not sufficient, and if it exceeds 3% by mass, the torque capacity of the clutch is insufficient.

  In the lubricating oil composition of the present invention, a known lubricating oil additive may be blended alone or in combination of several kinds as necessary for the purpose of further enhancing the performance within a range not impairing the performance of the present invention. . Examples of such lubricating oil additives include viscosity modifiers, rust inhibitors, demulsifiers, metal deactivators, ashless dispersants, antioxidants, corrosion inhibitors, antifoaming agents, and colorants. It is done.

The viscosity modifier is a viscosity modifier other than a copolymer of an α-olefin and an ester monomer having a polymerizable unsaturated bond. Examples of the viscosity modifier include a non-dispersed or dispersed poly (meth) acrylate viscosity modifier and a styrene-maleic anhydride copolymer viscosity modifier. Among these, the viscosity modifier is preferably a non-dispersed or dispersed poly (meth) acrylate viscosity modifier, and more preferably a non-dispersed or dispersed polymethacrylate viscosity modifier. Other examples of the viscosity modifier include a non-dispersed or dispersed ethylene-α-olefin copolymer or a hydride thereof, polyisobutylene or a hydride thereof, a styrene-diene hydrogenated copolymer, and a polyalkylstyrene. be able to.
In the present invention, a poly (meth) acrylate-based viscosity modifier is preferred from the viewpoint that low temperature viscosity characteristics and viscosity temperature characteristics need to be good.
Further, from the viewpoint of the shear stability of the composition, the weight average molecular weight is preferably 50,000 or less, and preferably 30,000 or less. From the viewpoint of the thickening effect, 5000 or more is preferable.
The weight average molecular weight means that two columns of Tosoh GMHHR-M (7.8 mm ID × 30 cm) are used in series in a Waters 150-C ALC / GPC apparatus, tetrahydrofuran is used as a solvent, and a temperature of 23 It means the weight average molecular weight in terms of standard polystyrene measured using a differential refractometer (RI) detector under the conditions of ° C., flow rate of 1 mL / min, sample concentration of 1 mass%, and sample injection volume of 75 μL.

  Examples of the rust preventive include alkenyl succinic acid ester and polyhydric alcohol ester.

  Examples of the demulsifier include polyalkylene glycol nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and polyoxyethylene alkyl naphthyl ether.

  Examples of the metal deactivator include imidazoline, pyrimidine derivatives, benzotriazole or derivatives thereof.

  Examples of the ashless dispersant include nitrogen-containing compounds that do not contain boron, such as succinimide, benzylamine, and polyamine, and their derivatives, which are exemplified in the description of the component (C).

  Examples of the antioxidant include ashless antioxidants such as phenols and amines, and metal antioxidants such as copper and molybdenum. Specifically, for example, as a phenol-based ashless antioxidant, 4,4′-methylenebis (2,6-di-tert-butylphenol), 4,4′-bis (2,6-di-tert- Butylphenol) and the like are amine-based ashless antioxidants such as phenyl-α-naphthylamine, alkylphenyl-α-naphthylamine, dialkyldiphenylamine, and diphenylamine.

  Examples of the corrosion inhibitor include benzotriazole, tolyltriazole, and imidazole compounds.

As the defoaming agent, for example, 100,000 mm kinematic viscosity at 25 ° C. is 1000 mm ² / s or more ² / s or less silicone oil, alkenylsuccinic acid derivatives, esters of polyhydroxy aliphatic alcohols and long-chain fatty acids, methyl salicylate And esters of o-hydroxybenzyl alcohol and the like.

  The content of these other additives may be 0.01 to 20% by mass based on the total amount of the lubricating oil composition.

  The sulfur content of the lubricating oil composition of the present invention is 0.3% by mass or more, preferably 0.35% by mass or more in terms of elemental sulfur. Moreover, it is preferable that it is 3 mass% or less, and 2 mass% or less is more preferable. If it is less than 0.3% by mass, the effect of preventing wear and improving the friction coefficient between metals is not sufficient. If it exceeds 3 mass%, the judder prevention performance of the clutch will be insufficient.

  The phosphorus content of the lubricating oil composition of the present invention is 0.2% by mass or less, preferably 0.15% by mass or less, in terms of phosphorus element. Moreover, it is preferable that it is 0.03 mass% or more, and 0.05 mass% or more is more preferable. If it is less than 0.03% by mass, the effect of preventing wear or shudder is not sufficient, and if it exceeds 0.2% by mass, the compatibility with the sealing material is insufficient.

The use of the lubricating oil composition of the present invention is not limited and can be used widely. However, it can be preferably used for a continuously variable transmission, particularly a metal belt type continuously variable transmission.
This is because the lubricating oil composition of the present invention contains a specific amount of thiadiazole and a phosphorus-containing sulfur-based additive, and the content of sulfur and phosphorus in the composition is within the specific range described above. The belt capacity of the continuously variable transmission, that is, the high metal-to-metal friction coefficient, extreme pressure, and wear resistance can be compatible, and by adding a specific amount of boron compound, the metal / metal dynamic friction coefficient can be set high. This is because the noise of the metal belt generated during sudden acceleration can be suppressed.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

(Examples 1-15 and Comparative Examples 1-5)
Lubricating oil compositions having the compositions shown in Table 1 were prepared. The addition amount (% by mass) of each additive is based on the total amount of the composition. The properties of each lubricating oil composition were evaluated and listed in Table 1.

Claims (6)

  Base oil, (A) thiadiazole 0.3% by mass or more based on total composition, (B) sulfur-based additive containing phosphorus 0.05% by mass or more based on total composition, and (C) containing boron An ashless dispersant is contained in an amount of 50 mass ppm or more in terms of boron element in terms of the total amount of the composition, the sulfur content of the composition is 0.3 mass% or more in terms of sulfur element, and the phosphorus content is 0.2 mass in terms of phosphorus element. % Lubricating oil composition characterized by being less than or equal to%.   The lubricating oil composition according to claim 1, wherein the base oil comprises a base oil selected from a hydrorefined base oil, a wax isomerized base oil and a poly α-olefin. (B) The lubricating oil composition according to claim 1, wherein the sulfur-containing additive containing phosphorus is a thiophosphate ester having a carboxy group at a terminal represented by the following general formula (4): .

(In the formula (4), R ₁ is a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, R ₂ is a hydrocarbon group having 1 to 20 carbon atoms, and R ₃ is a divalent hydrocarbon having 1 to 8 carbon atoms. Group.)   (D) Lubricating oil composition in any one of Claims 1-3 containing boric acid ester and / or alkali metal borate or its hydrate.   The lubricating oil composition according to any one of claims 1 to 4, further comprising at least one additive selected from a metallic detergent, a viscosity index improver, and a friction modifier.   The lubricating oil composition according to any one of claims 1 to 5, wherein the lubricating oil composition is for a continuously variable transmission.