JP2019147919A - Lubricant composition - Google Patents

Abstract

To provide a lubricant composition that can maintain a high coefficient of friction between metals in a boundary lubrication area, and can keep the coefficient of the friction between the metals low in an area with a high rotation and a mild lubrication condition.SOLUTION: The lubricant composition comprises a lubricating base oil, a friction modifier having a specific structure, and an antiwear agent having a specific structure, wherein a content of the antiwear agent is 50 to 950 mass ppm in terms of phosphorus elements based on a total amount of the lubricant composition.SELECTED DRAWING: None

Description

  The present invention relates to a lubricating oil composition.

  Lubricating oil (transmission lubricating oil) for transmitting power from the engine to the transmission is used in transmissions such as automatic transmissions and continuously variable transmissions. A friction modifier is blended with the lubricating oil for the transmission in order to adjust its friction characteristics. For example, fatty acid amides are known as friction modifiers (see Patent Document 1 below).

JP 2014-177608 A

  The transmission has belts, pulleys, bearings, oil pumps, etc. as components, and the lubrication area varies depending on the components. Therefore, the transmission lubricant used for these components is different for each component. Different performance is required. For example, in a belt and a pulley, it is required to maintain a high coefficient of friction between metals in a boundary lubrication region for power transmission. On the other hand, in order to achieve fuel saving, it is required to keep the coefficient of friction between metals low in a region where the lubrication conditions are mild, such as a bearing or oil pump that operates at high speed. However, it cannot be said that the conventional transmission lubricants are always satisfied with these required characteristics.

  The present invention has been made in view of such circumstances, and maintains a high coefficient of friction between metals in the boundary lubrication region, while keeping the coefficient of friction between metals low in a region where the lubrication condition is high at high speed. It is an object of the present invention to provide a lubricating oil composition that can be used.

  The present invention is at least one selected from the group consisting of a lubricating base oil, a friction modifier represented by the following general formula (1), the following general formula (2-1) and the following general formula (2-2). A lubricating oil composition comprising: a seed antiwear agent, wherein the content of the antiwear agent is 50 to 950 mass ppm in terms of phosphorus element based on the total amount of the lubricating oil composition.

［式（１）中、Ｒは炭素数３〜３０の炭化水素基を示し、Ｒ’は水素原子又は下記一般式（１’）で表される基を示し、ｎは１〜３の整数を示す。

（式（１’）中、ｍは１〜３の整数を示す。）］

[In the formula (1), R represents a hydrocarbon group having 3 to 30 carbon atoms, R ′ represents a hydrogen atom or a group represented by the following general formula (1 ′), and n represents an integer of 1 to 3. Show.

(In Formula (1 ′), m represents an integer of 1 to 3)]

［式（２−１）中、Ｒ^１及びＲ^２はそれぞれ独立に、水素原子又は炭素数４〜２０の炭化水素基を示す。］

[In Formula (2-1), R ¹ and R ² each independently represent a hydrogen atom or a hydrocarbon group having 4 to 20 carbon atoms. ]

［式（２−２）中、Ｒ^３は水素原子、硫黄を含んでいてもよい炭素数４〜２０の炭化水素基又は芳香族基を示し、Ｒ^４は硫黄を含んでいてもよい炭素数４〜２０の炭化水素基又は芳香族基を示す。］

[In Formula (2-2), R ³ represents a hydrogen atom or a hydrocarbon group or aromatic group having 4 to 20 carbon atoms which may contain sulfur, and R ⁴ represents a carbon number which may contain sulfur. 4-20 hydrocarbon groups or aromatic groups are shown. ]

  According to the present invention, it is possible to provide a lubricating oil composition that can maintain a high coefficient of friction between metals in a boundary lubrication region, and can keep the coefficient of friction between metals low in a region where the lubrication condition is high at a high rotation speed. it can.

  The lubricating oil composition according to this embodiment includes a lubricating base oil, a friction modifier, and an antiwear agent. Hereinafter, each component will be described in detail.

[Lubricant base oil]
The lubricating base oil used in the present embodiment is not particularly limited, and any of mineral oil and synthetic oil can be used.

  As mineral oils, lubricating oil fractions obtained by atmospheric distillation and vacuum distillation of crude oil are removed from solvents, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing, clay. Examples thereof include paraffinic and naphthenic mineral oils, normal paraffins, isoparaffins, and the like, which are purified by combining purification treatments such as treatment alone or in combination of two or more.

  As the synthetic oil, various conventionally known oils can be used. For example, poly α-olefin (including α-olefin copolymer), polybutene, polyol ester, dibasic acid ester, phosphate ester, polyphenyl ether, alkylbenzene, alkylnaphthalene, polyoxyalkylene glycol, neopentyl glycol, silicone Oil, trimethylolpropane, pentaerythritol, hindered ester, and the like can be used.

  These lubricating base oils can be used singly or in combination of two or more, and may be used in combination of mineral oil and synthetic oil. As the lubricating base oil, a hydrocarbon base oil is preferably used from the viewpoint of exhibiting the effects of the present invention at a higher level. When using an ester base oil as the lubricating base oil, the content of the ester base oil is 30% by mass based on the total amount of the lubricating base oil from the viewpoint of exhibiting the effects of the present invention at a higher level. The following are preferable and 10 mass% or less is more preferable.

The kinematic viscosity of the lubricating base oil can be appropriately selected according to the use and purpose of the lubricating oil composition. For example, when the lubricating oil composition according to the present embodiment is used as a drive system lubricating oil, the upper limit value of the kinematic viscosity at 100 ° C. of the lubricating base oil is preferably 30 mm ² / s or less, more preferably 20 mm ² / s. Hereinafter, it is more preferably 10 mm ² / s or less. On the other hand, the lower limit value of the kinematic viscosity at 100 ° C. of the lubricating base oil is not particularly limited, and is, for example, 1 mm ² / s or more, 2 mm ² / s or more, or 3 mm ² / s or more. When the kinematic viscosity at 100 ° C. is in the above range, the friction at the sliding portion of the transmission can be sufficiently reduced and the low temperature characteristics are also improved. On the other hand, if the kinematic viscosity at 100 ° C. exceeds 30 mm ² / s, the fuel efficiency deteriorates and the low-temperature viscosity tends to be too high. Further, if the kinematic viscosity at 100 ° C. is less than 1 mm ² / s, the amount of wear increases in the sliding portion of the automatic transmission, the lubrication performance may be reduced, and the evaporability increases and the amount of lubricating oil consumption increases. There is a risk.

  The kinematic viscosity in the present invention means a kinematic viscosity measured according to JIS K2283: 2000.

  In addition, the physical properties such as the viscosity index and the NOACK evaporation amount of the lubricating base oil used in the present embodiment can be appropriately set according to the use of the lubricating oil composition.

  The content of the lubricating base oil may be, for example, 50% by mass or more, 70% by mass or more, or 90% by mass or more based on the total amount of the lubricating oil composition.

[Friction modifier]
The friction modifier used in this embodiment is represented by the following general formula (1).

  In the formula (1), R represents a hydrocarbon group having 3 to 30 carbon atoms. The hydrocarbon group represented by R is preferably a linear alkyl group, a branched alkyl group, a linear alkenyl group or a branched alkenyl group, more preferably a linear alkyl group or a linear alkenyl group, A straight chain alkenyl group is preferable. The carbon number of the hydrocarbon group represented by R is preferably 6 to 24, more preferably 8 to 20, and still more preferably 10 to 18. Examples of the hydrocarbon group having 3 to 30 carbon atoms represented by R include a stearyl group, an isostearyl group, and an oleyl group. Among these, from the viewpoint of further improving the friction characteristics of the lubricating oil composition, R Is preferably an isostearyl group or an oleyl group.

  In formula (1), R ′ represents a hydrogen atom or a group represented by the following general formula (1 ′), preferably a group represented by the following general formula (1 ′).

  In the formula (1 ′), m represents an integer of 1 to 3. m preferably represents an integer of 1 to 2, and more preferably 2.

  In formula (1), n shows the integer of 1-3. n preferably represents an integer of 1 to 2, and more preferably 2.

  Examples of the friction modifier represented by the formula (1) described above include compounds represented by the following formulas (1a) to (1h).

  In the lubricating oil composition, the friction modifier represented by the general formula (1) may be used alone or in combination of two or more.

  The content of the friction modifier represented by the formula (1) is preferably 0.01% by mass or more, based on the total amount of the lubricating oil composition, from the viewpoint of sufficiently ensuring the friction characteristics of the lubricating oil composition. Preferably it is 0.1 mass% or more, More preferably, it is 0.3 mass% or more. The content of the lubricating oil composition is the total amount of the lubricating oil composition from the viewpoint of more effectively maintaining the intermetallic friction coefficient in the boundary lubrication region while maintaining the effect of reducing the intermetallic friction coefficient low in the high rotation and mild lubrication region. Is preferably 5% by mass or less, more preferably 1% by mass or less, still more preferably 0.8% by mass or less, and particularly preferably 0.5% by mass or less. In addition, when using 2 or more types of friction modifiers represented by Formula (1) in combination, the total of these content should just be in the said numerical range.

[Antiwear]
The lubricating oil composition according to the present embodiment includes at least one wear inhibitor selected from the group consisting of the following general formula (2-1) and a general formula (2-2) described later.

In formula (2-1), R ¹ and R ² each independently represent a hydrogen atom or a hydrocarbon group having 4 to 20 carbon atoms. The hydrocarbon group having 4 to 20 carbon atoms represented by R ¹ and R ² is preferably an alkyl group having 4 to 20 carbon atoms. Examples of the hydrocarbon group having 4 to 20 carbon atoms represented by R ¹ and R ² include a butyl group.

  Examples of the antiwear agent represented by the formula (2-1) include phosphoric acid and alkyl acid phosphates having 4 to 20 carbon atoms. Among them, the friction characteristics of the lubricating oil composition are more effectively exhibited. Furthermore, from the viewpoint of sufficiently securing the capacity of the lockup clutch, it is preferably at least one selected from the group consisting of phosphoric acid and dibutyl phosphate.

In Formula (2-2), R ³ represents a hydrogen atom or a hydrocarbon group having 4 to 20 carbon atoms or an aromatic group that may contain sulfur. Examples of the hydrocarbon group R ³ may 4 to 20 carbon atoms also include sulfur represented by, for example, 3-thiopentyl group. Examples of the aromatic group represented by R ³ include a phenyl group.

In formula (2-2), R ⁴ represents a hydrocarbon group having 4 to 20 carbon atoms or an aromatic group which may contain sulfur. Examples of the hydrocarbon group having 4 to 20 carbon atoms which may contain sulfur represented by R ⁴ , an aromatic group, and preferred embodiments thereof include the same as those described for R ³ above.

The antiwear agent represented by formula (2-2) exhibits the friction characteristics of the lubricating oil composition more effectively, and further from the viewpoint of sufficiently securing the capacity of the lockup clutch, R ³ is a hydrogen atom or an aromatic group, preferably R ⁴ is a hydrocarbon group or an aromatic group which may having 4 to 20 carbon atoms also contain sulfur, R ³ is a hydrogen atom and R ⁴ is contains sulfur More preferably, it is a hydrocarbon group having 4 to 20 carbon atoms, or R ³ and R ⁴ are both aromatic groups.

  Examples of the antiwear agent represented by the formula (2-2) include diphenyl hydrogen phosphite and 3-thiopentyl hydrogen phosphite.

  In the lubricating oil composition, the antiwear agents represented by General Formula (2-1) and General Formula (2-2) may be used singly or in combination of two or more.

  The content of the antiwear agent described above is 50 to 950 mass ppm in terms of phosphorus element, based on the total amount of the lubricating oil composition. When the content of the antiwear agent is within the above range, the friction characteristics of the lubricating oil composition can be exhibited more effectively, and the capacity of the lockup clutch can be sufficiently secured. On the other hand, if the content of the anti-wear agent is less than 50 ppm by mass based on the total amount of the lubricating oil composition, the desired anti-wear effect may not be obtained. Due to the inhibitory effect of the agent, there is a possibility that the effect of the friction characteristics by the friction modifier described above cannot be sufficiently obtained. From such a viewpoint, the content of the antiwear agent is preferably 100 mass ppm or more, more preferably 300 mass ppm or more, and further preferably 500 mass ppm or more in terms of phosphorus element, based on the total amount of the lubricating oil composition. Preferably, it is 900 mass ppm or less, More preferably, it is 800 mass ppm or less, More preferably, it is 700 mass ppm or less. In addition, when using the said antiwear agent in combination of 2 or more types, the sum total of these content should just be in the said numerical range.

[Other additives]
The lubricating oil composition according to the present embodiment may further contain an optional additive in addition to the friction modifier and the wear inhibitor as necessary for the purpose of further improving the performance.

  As the additive, for example, an additive that can be added to a lubricating oil composition used in a transmission can be used without particular limitation. Examples of the additive include a viscosity index improver, an ashless dispersant and / or a friction modifier other than the friction modifier represented by the general formula (1), the general formula (2-1), and the general formula (2). -2), antiwear agents other than the antiwear agent, metal detergents, extreme pressure agents, antioxidants, antifoaming agents, and the like. These additives can be used individually by 1 type or in combination of 2 or more types.

  Examples of the viscosity index improver include non-dispersed or dispersed viscosity index improvers. Specifically, non-dispersed or dispersed poly (meth) acrylates, non-dispersed or dispersed ethylene-α-olefin copolymers or hydrides thereof, polyisobutylene or hydrides thereof, styrene-diene hydrogenation copolymers. Examples thereof include a polymer, a styrene-maleic anhydride ester copolymer, a poly (meth) acrylate-styrene copolymer, a poly (meth) acrylate-olefin copolymer, and a polyalkylstyrene. The weight average molecular weight of these viscosity index improvers is not particularly limited, and is usually 10,000 to 1,000,000. The content of the viscosity index improver is not particularly limited, but is usually 0.5 to 35% by mass based on the total amount of the lubricating oil composition.

  Ashless dispersants and / or friction modifiers other than the friction modifier represented by the general formula (1) include amine compounds, imide compounds, fatty acid esters, fatty acid amides, fatty acids, aliphatic alcohols, aliphatic ethers, molybdenum dithiols. Examples thereof include organic molybdenum compounds such as phosphate (MoDTP) and molybdenum dithiocarbamate (MoDTC), graphite, molybdenum disulfide, antimony sulfide, boron compounds, polytetrafluoroethylene, and the like. The content of the ashless dispersant and / or the friction modifier is not particularly limited, but is usually 0.1 to 10% by mass, 0.5 to 8% by mass, or 1 to 7% by mass based on the total amount of the lubricating oil composition. %.

  Examples of the antiwear agent other than the antiwear agent represented by the general formula (2-1) and the general formula (2-2) include a sulfur-based antiwear agent. Examples of the sulfur-based antiwear agent include sulfur-containing compounds such as disulfides, sulfurized fats and oils, sulfurized esters, dithiocarbamates, and zinc dithiocarbamates. The content of these antiwear agents is not particularly limited, but is usually 0.01 to 10% by mass based on the total amount of the lubricating oil composition.

  Examples of metal detergents include calcium sulfonate, magnesium sulfonate, barium sulfonate, calcium salicylate, magnesium salicylate, calcium phenate, barium phenate, and other normal salts, basic salts, and overbased salts. Can be mentioned. The content of the metal detergent is not particularly limited, but is usually 0.1 to 10% by mass based on the total amount of the lubricating oil composition. Moreover, when using a calcium-type detergent as a metal-type detergent, content of a calcium-type detergent is 10-1500 mass ppm, 100-1300 mass ppm in conversion of a calcium element on the basis of the lubricating oil composition whole quantity, or It may be 200 to 800 ppm by mass.

  Examples of extreme pressure agents include thiadiazole, polysulfide, sulfurized olefin, and the like. The extreme pressure agent content is not particularly limited, but is usually 0.01 to 10% by mass based on the total amount of the lubricating oil composition. Further, for example, when a sulfur-based extreme pressure agent such as thiadiazole is used as the extreme pressure agent, the content of the sulfur-based extreme pressure agent is 1 to 1500 ppm by mass in terms of sulfur element, based on the total amount of the lubricating oil composition. It may be -1000 mass ppm, 100-800 mass ppm, or 300-600 mass ppm.

  Examples of the antioxidant include phenol-based, amine-based, copper-based, and molybdenum-based antioxidants. Specifically, amine-based antioxidants such as alkylated diphenylamine, phenyl-α-naphthylamine, alkylated-α-naphthylamine, 2,6-di-t-butyl-4-methylphenol, 4,4′-methylenebis And hindered phenol antioxidants such as (2,6-di-t-butylphenol). The content of the antioxidant is not particularly limited, but is usually 0.05 to 5% by mass based on the total amount of the lubricating oil composition.

  As the antifoaming agent, any compound usually used as an antifoaming agent for lubricating oil can be used, and examples thereof include silicones such as dimethyl silicone and fluorosilicone. One or two or more compounds arbitrarily selected from these can be blended in any amount.

  The lubricating oil composition according to the present embodiment can maintain a high coefficient of friction between metals in the boundary lubrication region, and can keep the coefficient of friction between metals low in a region where the lubrication condition is high at a high rotation speed. Fuel consumption can be achieved while increasing the capacity. Furthermore, the lubricating oil composition according to the present embodiment can ensure the torque capacity of the lockup clutch (LC) (friction characteristics of the paper material). Therefore, it is suitable as a lubricating oil composition for transmissions such as automatic transmissions and continuously variable transmissions (particularly belt type continuously variable transmissions). Moreover, it can also be used as lubricating oil for construction machines, agricultural machines, manual transmissions, motorcycle gasoline engines, diesel engines, gas engines, shock absorbers, etc., equipped with transmissions having wet clutches and wet brakes.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example and a comparative example, the following Examples are not intended to limit this invention.

[Examples 1 to 18, Comparative Examples 1 to 8]
Lubricating oil compositions having the compositions shown in Tables 1 to 6 were prepared using the base oils and additives shown below. In Tables 1 to 6, the content of each component indicates the content ratio based on the total amount of the lubricating oil composition.

(Base oil)
A: Hydrocracked mineral oil (kinematic viscosity at 100 ° C .: 3.3 mm ² / s)

(Friction modifier)
B1: Compound represented by the following formula (1a).

B2: Compound represented by the following formula (1b).

B3: A compound represented by the following formula (1c).

B4: Compound represented by the following formula (1d).

B5: A compound represented by the following formula (1e).

B6: Compound represented by the following formula (1f).

B7: A compound represented by the following formula (1 g).

B8: Compound represented by the following formula (1h).

B9: A compound represented by the following formula (1i).

B10: Compound represented by the following formula (1j).

B11: Compound represented by the following formula (1k).

B12: a compound represented by the following formula (1l), in which each R is independently a C ₁₂ H ₂₅ group or a C ₁₄ H ₂₉ group (mixture: cocoamine).

B13: A compound represented by the following formula (1m).

(Antiwear agent)
C1: Dibutyl phosphate (phosphorus element content: 15.5% by mass)
C2: Diphenyl hydrogen phosphite (phosphorus element content: 13.2% by mass)
C3: phosphoric acid (phosphorus element content: 30.0% by mass)
C4: 3-thiopentyl hydrogen phosphite (phosphorus element content: 8.4% by mass)
C5: Tetracosyl acid phosphate (phosphorus element content: 5.3 mass%)

(Ashless dispersant)
D: Boron-containing polybutenyl succinimide

(Metal-based detergent)
E: Calcium sulfonate (calcium element content: 11.4% by mass, base number: 300 mgKOH / g)

(Extreme pressure agent)
F: Thiadiazole (Sulfur element content: 36% by mass)

(Antioxidant)
G: Phenolic antioxidant

(Viscosity index improver)
H: Polymethacrylate (weight average molecular weight: 35000)

(Defoamer)
I: Polydimethylsiloxane

[Evaluation test of lubricating oil composition]
(Coefficient of friction between metals)
Using a block-on-ring tester (LFW-1) described in ASTM D 2174, the friction coefficient (μ) of the lubricating oil composition was measured under the following conditions to evaluate the friction coefficient of the lubricating oil composition.
Test piece (ring) :: Falex S-10 Test Ring (SAE 4620 Steel)
Test piece (block): Falex H-60 Test Block (SAE01 Steel)
Oil temperature: 80 ° C
Load: 400N

  The test is carried out for 20 minutes at a peripheral speed (sliding speed) of 1 m / s, and then the friction coefficient at the sliding speed of 0.1 m / s (friction coefficient in the boundary lubrication region: μ1) and the sliding speed. The friction coefficient at 5 m / s (friction coefficient at high rotation: μ2) was measured, and the value of μ2 / μ1 was calculated. The results are shown in Tables 1-6. The lower the μ2 / μ1 value, the higher the friction coefficient between metals in the boundary lubrication region, and the lower the friction coefficient between metals in the region where the lubrication conditions are high and the rotation speed is mild. It can be said.

(Torque capacity)
The torque capacities of the lubricating oil compositions prepared in Examples 1 to 18 described above are based on JASO M349: 2010 in terms of the μ-V characteristics of the lubricating oil composition at 80 ° C. using a low speed slip test device (LVFA). The friction coefficient μ (μ0.06) at the sliding speed of 0.06 m / s in the μ-V characteristic was calculated.

  Μ2 / μ0.06 was calculated from the obtained value of μ0.06 and the value of μ2 obtained by the measurement of the intermetal friction coefficient. The results are shown in Tables 7-9. It can be said that the smaller the value of μ2 / μ0.06, the greater the torque capacity of the lock-up clutch, and the better the fuel economy and LC performance (friction characteristics of the paper material).

Claims (1)

At least one type of wear prevention selected from the group consisting of a lubricating base oil, a friction modifier represented by the following general formula (1), the following general formula (2-1) and the following general formula (2-2) An agent,
Lubricating oil composition whose content of said antiwear agent is 50-950 mass ppm in conversion of phosphorus element on the basis of lubricating oil composition whole quantity.

[In the formula (1), R represents a hydrocarbon group having 3 to 30 carbon atoms, R ′ represents a hydrogen atom or a group represented by the following general formula (1 ′), and n represents an integer of 1 to 3. Show.

(In Formula (1 ′), m represents an integer of 1 to 3)]

[In Formula (2-1), R ¹ and R ² each independently represent a hydrogen atom or a hydrocarbon group having 4 to 20 carbon atoms. ]

[In Formula (2-2), R ³ represents a hydrogen atom or a hydrocarbon group or aromatic group having 4 to 20 carbon atoms which may contain sulfur, and R ⁴ represents a carbon number which may contain sulfur. 4-20 hydrocarbon groups or aromatic groups are shown. ]