WO2011099207A1 - Lubricating oil composition - Google Patents

Abstract

Disclosed is a lubricating oil composition that is characterized by comprising a mixture of (A) in the range of 5 mass% to 70 mass%, based on the total amount of the composition, of a lubricant base oil in which the sulfur content is no more than 0.03 mass%, based on the total amount of the composition, and the kinematic viscosity at 100°C is in the range of 0.5 mm²/s to 1.5 mm²/s, and (B) in the range of 15 mass% to 30 mass%, based on the total amount of the composition, of a poly-α-olefin in which the kinematic viscosity at 100°C is at least 150 mm²/s.

Description

Lubricating oil composition

The present invention relates to a lubricating oil composition.

In recent years, against the background of the global carbon dioxide emission problem and the increase in global energy demand, there has been an increasing demand for fuel saving in automobiles. Among them, transmissions, which are parts of automobiles, are required to contribute to fuel saving more than ever before.
For example, one way to save fuel in transmissions is to reduce the viscosity of the lubricating oil. However, the reduced viscosity of the lubricating oil reduces the oil film retention at high temperatures, causing seizures and fatigue. Problems such as a reduction in life may occur.

Patent Document 1 reports that a lubricating oil composition capable of maintaining the speed change characteristics for a long period of time is blended and optimized with various additives. However, since the invention described in Patent Document 1 is not intended to save fuel, the kinematic viscosity is high, and the fatigue life when the viscosity is reduced has not been studied.
On the other hand, the viscosity index of about 150 to 250 is currently used in the market, but in order to further reduce fuel consumption, the viscosity on the low temperature side is maintained from the viewpoint of low temperature startability while maintaining the high temperature side viscosity. A so-called high viscosity index that lowers the viscosity of the resin is desired.
For example, the lubricating oil composition disclosed in Patent Document 2 uses polymethacrylate (PMA) as a viscosity index improver to improve the viscosity index. In addition, the lubricating oil compositions disclosed in Patent Document 3 and Patent Document 4 use a high-viscosity synthetic oil (poly-α-olefin: PAO) to improve viscosity characteristics and to further improve fatigue life. Copolymer (OCP) is blended.

JP 2001-262176 A JP 2006-117852 A JP 2008-208220 A JP 2008-208221 A

However, in order to increase the viscosity at high temperatures, the addition of a viscosity index improver is effective, but the viscosity decrease during shearing (decrease in shear stability) is large, and wear and fatigue associated with a decrease in oil film forming ability The problem is concerned. Further, improvement in fatigue life and increase in the viscosity index are in a reciprocal relationship, and Patent Document 2 has a problem that although the viscosity index is improved, the oil film retention is poor. Moreover, in patent documents 3 and 4, the viscosity index more than the viscosity index which PAO has by the mixing | blending of OCP is not obtained, and high viscosity index increase is not examined. That is, a technique for improving the viscosity index while having a sufficient fatigue life has not been realized and studied.

Accordingly, an object of the present invention is to provide a lubricating oil composition that maintains the required shear stability, has excellent low-temperature viscosity characteristics, has high fuel efficiency, and can maintain a fatigue life. It is in.

As a result of intensive studies to solve such problems, the present inventor has found that the above problems can be solved by combining specific base oils and additives as follows. It came to complete.

That is, the present invention provides the following lubricating oil composition.
(1) A lubricating oil composition (A) for a lubricating oil having a sulfur content of 0.03% by mass or less and a kinematic viscosity at 100 ° C. of 0.5 mm ² / s to 1.5 mm ² / s. The base oil is 5% by mass or more and 70% by mass or less based on the total amount of the composition, and (B) the poly-α-olefin having a kinematic viscosity at 100 ° C. of 150 mm ² / s or more is 15% by mass or more and 30% by mass based on the total amount of the composition. % Or less, and a lubricating oil composition comprising:

(2) The above lubricating oil composition, further comprising a silicone oil having a kinematic viscosity at 100 ° C. of 0.5 mm ² / s to 4 mm ² / s. .

(3) The above lubricating oil composition, further comprising a polymethacrylate having a mass average molecular weight (Mw) of 100,000 or more.

(4) The lubricating oil composition described above, further comprising a poly-α-olefin having a kinematic viscosity at 100 ° C. of 1.5 mm ² / s to 2.5 mm ² / s. A lubricating oil composition.

(5) The above-described lubricating oil composition, wherein the kinematic viscosity at 100 ° C. of the component (A) is 0.7 mm ² / s to 1.3 mm ² / s, and the component (B) at 100 ° C. A polymethacrylate having a kinematic viscosity of 150 mm ² / s to 400 mm ² / s and a mass average molecular weight of 300,000 or more is 0.1% by mass to 5.0% by mass based on the total amount of the composition, and a kinematic viscosity at 100 ° C. Characterized by being blended with a poly-α-olefin having a weight ratio of 1.7 mm ² / s to 2.1 mm ² / s in an amount of 0.1% by weight to 60% by weight based on the total amount of the composition. Oil composition.

(6) The lubricating oil composition described above, wherein the lubricating oil composition is used for a transmission.

According to the present invention, it is possible to provide a lubricating oil composition that maintains shear stability as before and that is excellent in low-temperature viscosity characteristics. Moreover, when this lubricating oil composition is used as a lubricating oil for a transmission or the like, fuel efficiency is high and a fatigue life can be maintained.

The lubricating oil composition of the present invention is characterized by blending the aforementioned components. Details will be described below.

[Component (A)]
In the lubricating oil composition of the present invention, the component (A) has a sulfur content of 0.03% by mass or less, and a kinematic viscosity at 100 ° C. of 0.5 mm ² / s to 1.5 mm ² / s, more preferably. Is formed by blending a base oil for lubricating oil of 0.7 mm ² / s to 1.3 mm ² / s in an amount of 5% by mass to 70% by mass based on the total amount of the composition.
(A) When the sulfur content in a component exceeds 0.03 mass%, oxidation stability will worsen.
If the kinematic viscosity at 100 ° C. is smaller than 0.5 mm ² / s, the evaporating property is significantly increased, and there is a possibility that the amount of lubricating oil consumption increases. Moreover, when the kinematic viscosity at 100 ° C. is larger than 1.5 mm ² / s, the viscosity index decreases.
Further, when the blending amount is less than 5% by mass, the viscosity index decreases, and when it exceeds 70% by mass, the viscosity of the lubricating oil composition decreases, and wear of mechanical parts increases when used for a transmission. Because there is a fear, it is not preferable.

As the base oil used in component (A), both mineral oil and synthetic oil can be used, but mineral oil is preferred because a lower viscosity base material can be used.
The mineral oil is not particularly limited as long as it is generally used as a base oil for transmission lubricants. For example, a lubricating oil fraction obtained by subjecting crude oil to atmospheric distillation and reduced pressure distillation is subjected to solvent removal. A paraffin type or a naphthene type that is appropriately combined with refining treatment such as solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing, or clay treatment can be suitably used.

As the component (A), a mineral oil or a synthetic oil having a kinematic viscosity at 100 ° C. within the above range may be used alone, or two or more selected from these may be used in an arbitrary ratio. You may mix and use.

[(B) component]
The lubricating oil composition of the present invention comprises, as component (B), a poly-α-olefin having a kinematic viscosity at 100 ° C. of 150 mm ² / s or higher, more preferably 150 mm ² / s or higher and 400 mm ² / s or lower. 15 mass% or more and 30 mass% or less are mix | blended on the basis.
When the kinematic viscosity at 100 ° C. is lower than 150 mm ² / s, the viscosity index is lowered, and when used for a transmission, there is a possibility that the wear of machine parts may increase.
When the blending amount is less than 15% by mass, the viscosity of the finished oil is lowered, and when used for a transmission, there is a possibility that wear of machine parts may increase, which is not preferable. Moreover, when there are more compounding quantities than 30 mass%, a viscosity raises and the problem that a friction loss increases may arise.

The lubricating oil composition of the present invention is a lubricating oil composition having excellent low-temperature viscosity characteristics while maintaining shear stability as before by blending the aforementioned component (A) and component (B). Can provide.

[Other ingredients]
The lubricating oil composition of the present invention can be further improved in its low-temperature viscosity characteristics by further blending the following components with the aforementioned components (A) and (B).
In the case of blending silicone oil, it is preferable to use one having a kinematic viscosity at 100 ° C. of 0.5 mm ² / s to 4 mm ² / s. If the kinematic viscosity at 100 ° C. is smaller than 0.5 mm ² / s, the flash point of the lubricating oil composition may be significantly reduced. If it is larger than 4 mm ² / s, the viscosity index may be lowered. This is undesirable.
A preferable blending amount of the silicone oil is 5% by mass or more and 50% by mass or less based on the total amount of the composition. Conventionally, silicone oil has a high viscosity index, but has a problem in solubility. In the lubricating oil composition of the present invention, the viscosity index can be improved without causing problems in solubility by blending each component in the aforementioned blending amount. However, when it is more than 50% by mass, the solubility is lowered and the silicone oil may be separated or precipitated.

In addition, it is preferable that the lubricating oil composition of the present invention further contains a polymethacrylate having a mass average molecular weight of 100,000 or more. Polymethacrylate is blended for the purpose of improving the viscosity index, but if the mass average molecular weight is less than 100,000, the ability to improve the viscosity index may be insufficient. A preferable blending amount of the polymethacrylate is 0.1% by mass or more and 5.0% by mass or less based on the total amount of the composition. When it is less than 0.1% by mass, the viscosity index improving ability is insufficient, and when it is more than 5.0% by mass, the shear stability of the lubricating oil composition may be lowered.

The lubricating oil composition of the present invention further has a kinematic viscosity at 100 ° C. of 1.5 mm ² / s to 2.5 mm ² / s, more preferably 1.7 mm ² / s to 2.1 mm ² / s. It is preferable to blend the poly-α-olefin.
If the kinematic viscosity at 100 ° C. is smaller than 1.5 mm ² / s, there may be a problem that the evaporability becomes higher. If it is larger than 2.5 mm ² / s, the viscosity of the lubricating oil composition becomes higher and the friction is increased. Loss may increase.
The blending amount of this PAO is preferably 0.1% by weight or more and 60% by weight or less based on the total amount of the composition, and particularly when blending more than 60% by weight, the viscosity index of the lubricating oil composition may be lowered. There is.

[Other additives]
The lubricating oil composition of the present invention may further contain other additives such as detergents, ashless dispersants, antiwear agents, friction modifiers, anti-proofing agents as necessary, as long as the effects of the present invention are not impaired. You may mix | blend a rusting agent, a metal deactivator, an antifoamer, antioxidant, a coloring agent, etc.

As detergents, neutral metal sulfonate, neutral metal phenate, neutral metal salicylate, neutral metal phosphonate, basic sulfonate, basic phenate, basic salicylate, overbased sulfonate, overbased salicylate, overbased Examples thereof include metal detergents such as phosphonates. A preferable blending amount is about 0.01% by mass or more and 10% by mass or less based on the total amount of the composition.
Examples of the ashless dispersant include succinimides, boron-containing succinimides, benzylamines, boron-containing benzylamines, succinic esters, monovalent or divalent typified by fatty acids or succinic acid. Examples thereof include amides of carboxylic acids. A preferable blending amount of the ashless dispersant is about 0.1% by mass or more and 20% by mass or less based on the total amount of the composition.

Examples of the antiwear agent include sulfur type antiwear agents such as thiophosphate metal salts (Zn, Pb, Sb, etc.) and thiocarbamic acid metal salts (Zn, etc.), phosphate esters (tricresyl phosphate), and the like. And phosphorus-based antiwear agents. A preferable blending amount of the antiwear agent is about 0.05% by mass or more and 5% by mass or less based on the total amount of the composition.
Examples of the friction modifier include polyhydric alcohol partial esters such as neopentyl glycol monolaurate, trimethylolpropane monolaurate, and glycerin monooleate (oleic acid monoglyceride). A preferable blending amount of the friction modifier is about 0.05% by mass or more and 4% by mass or less based on the composition.

Examples of the rust inhibitor include fatty acid, alkenyl succinic acid half ester, fatty acid soap, alkyl sulfonate, polyhydric alcohol fatty acid ester, fatty acid amide, oxidized paraffin, alkyl polyoxyethylene ether, and the like. A preferable blending amount of the rust inhibitor is about 0.01% by mass or more and 3% by mass or less based on the total amount of the composition.
Examples of the metal deactivator include benzotriazole, benzotriazole derivatives, triazole, triazole derivatives, imidazole, imidazole derivatives, thiadiazole, and the like, and these are used alone or in combination of two or more. A preferable blending amount of the metal deactivator is about 0.01% by mass or more and 5% by mass or less based on the total amount of the composition.

As the antifoaming agent, for example, a silicone compound, an ester compound, or the like is used alone or in combination of two or more. A preferable blending amount of the antifoaming agent is about 0.05% by mass or more and 5% by mass or less based on the total amount of the composition.
As the antioxidant, hindered phenol-based or amine-based, zinc alkyldithiophosphate (ZnDTP) or the like is preferably used. As the phenol type, bisphenol type and ester group-containing phenol type are particularly suitable. As the amine system, a dialkyldiphenylamine system or a naphthylamine system is suitable. A preferable blending amount of the antioxidant is about 0.05% by mass or more and 7% by mass or less.

The lubricating oil composition of the present invention formed by blending the above components maintains the viscosity at high temperature and the viscosity after shearing at the low temperature by satisfying the above-mentioned components, blending amount, and viscosity. Viscosity can be greatly reduced. Therefore, when used as a lubricating oil composition for a transmission, the fuel consumption is high and the fatigue life can be maintained, and the durability and reliability of the machine are not impaired.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
[Examples 1 to 5, Comparative Examples 1 to 5]
The lubricating oil composition was prepared with the composition shown in Table 1, and the kinematic viscosity at 100 ° C. and −40 ° C. and the viscosity after shearing of the prepared composition were measured by the following methods.
In addition, the components described in Table 1 are as follows.
Mineral oil-1: Mineral oil mineral oil having a sulfur content of 0.03% by mass or less, a kinematic viscosity at 100 ° C. of 1.0 mm ² / s, and a kinematic viscosity at 40 ° C. of 2.6 mm ² / s-2: a sulfur content of 0.1. 03 wt kinematic viscosity% at 100 ° C. or less is 6.5mm ² / s, 40 kinematic viscosity at ° C. of 37 mm ² / s mineral oil PAO-1: 100 kinematic viscosity at ° C. of 300 mm ² / s PAO
PAO-2: PAO having a kinematic viscosity at 100 ° C. of 1.8 mm ² / s
PAO-3: PAO having a kinematic viscosity at 100 ° C. of 100 mm ² / s
Ester: Butoxyethyl ester oleate with a kinematic viscosity of 3.4 mm ² / s at 100 ° C. 1: Polydimethylsiloxane silicone with a kinematic viscosity of 0.9 mm ² / s at 100 ° C. 2: Kinematic viscosity at 100 ° C. of 3. 4 mm ² / s polydimethylsiloxane PMA-1: polymethacrylate PMA-2 having a weight average molecular weight of 500,000: polymethacrylate having a weight average molecular weight of 20,000 Other additives: detergent (Ca sulfonate, etc.), dispersant (succinimide, etc.) , Extreme pressure additives and antiwear agents (sulfides, phosphate compounds, phosphorus sulfide compounds, etc.), antifoaming agents, copper deactivators, etc.

[Viscosity index]
The measurement was performed according to JIS K2283.
[Kinematic viscosity at 100 ° C and -40 ° C]
The measurement was performed according to JIS K2283.

[Kinematic viscosity before and after shearing]
According to JASO M-347, the kinematic viscosity at 140 ° C. before and after the 30-hour test was measured.

〔Evaluation results〕
From Table 1, it can be seen that in all of the examples of the present invention, the kinematic viscosity at −40 ° C. is significantly reduced while sufficiently maintaining the kinematic viscosity at 100 ° C. and the kinematic viscosity after shearing.
Further, from Examples 2 and 3, it can be seen that the kinematic viscosity at −40 ° C. is greatly reduced by the addition of silicone.
In addition, the selection and blending amount of mineral oil and PAO having different viscosities, and the blending amount of PMA are the first to satisfy the components and blending amounts of the present invention by comparing Examples 4 and 5 with Comparative Examples 2 to 5. It can be seen that the intended effect of the present application is achieved (kinematic viscosity at high temperature and kinematic viscosity after shearing are maintained, and kinematic viscosity at low temperature is greatly reduced). Further, from Comparative Examples 3 and 4, although the viscosity index is improved by blending polymethacrylate, the viscosity after shearing is lowered, so there is a concern that the wear resistance and the fatigue life may be reduced.

The present invention can be used as a lubricating oil composition, and in particular, can be suitably used as a transmission lubricating oil.

Claims (6)

A lubricating oil composition comprising:
(A) 5% by mass of a base oil for a lubricating oil having a sulfur content of 0.03% by mass or less and a kinematic viscosity at 100 ° C. of 0.5 mm ² / s to 1.5 mm ² / s based on the total amount of the composition. More than 70 mass%,
(B) A lubricating oil composition comprising 15% by mass or more and 30% by mass or less of poly-α-olefin having a kinematic viscosity at 100 ° C. of 150 mm ² / s or more based on the total amount of the composition. . The lubricating oil composition according to claim 1,
The lubricating oil composition characterized in that the kinematic viscosity at 100 ° C. is blended with the following silicone oil 0.5 mm ² / s or more ^{4 mm} 2 / s. The lubricating oil composition according to claim 1 or 2, wherein
Further, a lubricating oil composition comprising a polymethacrylate having a mass average molecular weight of 100,000 or more. The lubricating oil composition according to any one of claims 1 to 3, wherein
Further, a lubricating oil composition comprising a poly-α-olefin having a kinematic viscosity at 100 ° C. of 1.5 mm ² / s to 2.5 mm ² / s. The lubricating oil composition according to claim 1,
The kinematic viscosity at 100 ° C. of the component (A) is 0.7 mm ² / s to 1.3 mm ² / s,
The kinematic viscosity at 100 ° C. of the component (B) is 150 mm ² / s or more and 400 mm ² / s or less,
Furthermore, 0.1 mass% or more and 5.0 mass% or less of polymethacrylate having a mass average molecular weight of 300,000 or more based on the total amount of the composition,
A poly-α-olefin having a kinematic viscosity at 100 ° C. of 1.7 mm ² / s to 2.1 mm ² / s is blended with 0.1% by mass or more and 60% by mass or less based on the total amount of the composition. A lubricating oil composition. The lubricating oil composition according to any one of claims 1 to 5, wherein
A lubricating oil composition characterized by being used for a transmission.