WO2013062008A1

WO2013062008A1 - Lubrication oil composition

Info

Publication number: WO2013062008A1
Application number: PCT/JP2012/077480
Authority: WO
Inventors: 芳隆田本; 坪内　俊之
Original assignee: 出光興産株式会社
Priority date: 2011-10-28
Filing date: 2012-10-24
Publication date: 2013-05-02
Also published as: EP2772525A1; CN103930529A; US20140256607A1; IN2014CN03016A; MX2014004207A; JPWO2013062008A1; EP2772525A4

Abstract

Provided is a lubrication oil composition having an extremely high viscosity index and, at the same time, a low traction coefficient, which is a fluid friction coefficient in an elastohydrodynamic lubrication region, wherein the lubrication oil composition has excellent energy and fuel efficiency. The lubrication oil composition is characterized in containing the following components (A) and (B). (A) A low-viscosity synthesized oil, which is a compound having an ether bond in the molecule and a kinetic viscosity at 40°C of less than 10 mm²/s, the ratio between the number of oxygen atoms and carbon atoms constituting the compound (the O/C ratio) and the kinetic viscosity (mm²/s) of the compound at 40°C satisfying the following equation (1). Kinetic viscosity at 40°C ≤ 12 - [(O/C ratio) × 30] (1) (B) A high-viscosity synthesized oil, which is a hydrocarbon-based synthesized oil having a kinetic viscosity at 100°C of no less than 40 mm²/s, and which comprises one or more materials selected from α-olefin oligomers, hydrides of α-olefin oligomers, and ethylene-propylene copolymerization oligomers.

Description

Lubricating oil composition

The present invention relates to a lubricating oil composition, and more particularly to a lubricating oil composition having a high viscosity index and a low fluid friction coefficient in an elastohydrodynamic lubrication region, which is excellent in energy saving and fuel saving.

The original purpose of the lubricating oil is to reduce friction by an oil film formed on the sliding portion. Therefore, in order to form a strong oil film, it is advantageous that the lubricating oil has a high viscosity. However, the power required for the agitation and refueling of the lubricating oil results in a large energy loss, preventing improvement in energy saving and fuel saving. In recent years, therefore, the viscosity of lubricating oil has been reduced to reduce power loss.
However, when the viscosity of the lubricating oil is excessively reduced, it becomes difficult to form an oil film at the sliding portion at a high temperature, which may increase friction and cause abnormal wear.
Therefore, it is required to lower the viscosity in the normal temperature range while maintaining a high viscosity at a high temperature. This indicates that a change in the viscosity of the lubricating oil with respect to a change in temperature is extremely reduced, that is, a lubricating oil having an extremely high viscosity index (high VI) is necessary.

On the other hand, many mechanical devices use rolling bearings that support rotational motion and gears that transmit power as mechanical elements. The lubrication part of these rolling bearings and gears is in an elastohydrodynamic lubrication state, and the coefficient of friction there is called the traction coefficient. Therefore, in order to reduce the friction loss in the mechanical device in such a lubrication state, the traction of the lubricating oil (reduction of the traction coefficient) is required.
However, it is not easy to lower the traction coefficient. In particular, it is not easy to lower the traction coefficient at the same time while extremely increasing the viscosity index.

Conventionally, for example, Patent Document 1 discloses a technique for solving the problem of increasing the viscosity index and simultaneously reducing the traction coefficient.
Patent Document 1 discloses a method of adding a traction reducer as a method of lowering the traction coefficient of a lubricating oil composition containing a base stock having a viscosity of greater than 3 cSt at 100 ° C., that is, a traction coefficient, As traction reducers, monobasic acid esters and the like are described (see Patent Document 1, Claims 1 and 4). Also described is a lubricating oil composition having an increased viscosity index and a reduced traction coefficient.
However, the effect of reducing the traction coefficient of the lubricating oil composition described in Patent Document 1 is not always sufficient, and it is necessary to increase the traction coefficient, that is, the effect of reducing the traction coefficient.

Special table 2008-530268

The present invention provides a lubricating oil composition having an extremely high viscosity index and a low traction coefficient, which is a fluid friction coefficient in an elastohydrodynamic lubricating region, and excellent in energy saving and fuel saving. It is the purpose.

As a result of intensive studies to achieve the above object, the present inventors can achieve the above object effectively by blending a specific low viscosity synthetic oil having an ether bond and a specific high viscosity synthetic oil. I found. The present invention has been completed based on such findings.

That is, the present invention
1. A lubricating oil composition comprising the following component (A) and component (B):
(A) A compound having an ether bond in the molecule and having a kinematic viscosity at 40 ° C. of less than 10 mm ² / s, the ratio of the number of oxygen atoms and the number of carbon atoms constituting the compound (O / C ratio) and the compound The kinematic viscosity (mm ² / s) at 40 ° C. of the following formula (1)
Kinematic viscosity at 40 ° C. ≦ 12-[(O / C ratio) × 30] (1)
Low viscosity synthetic oil that satisfies
(B) A hydrocarbon-based synthetic oil having a kinematic viscosity at 100 ° C. of 40 mm ² / s or more, which is selected from α-olefin oligomers, α-olefin oligomer hydrides, and ethylene-propylene copolymer oligomers, or Two or more high viscosity synthetic oils.
2. The lubricating oil composition according to claim 1, wherein the component (A) is one or more compounds selected from the following (a-1) to (a-3).
(A-1) Dialkyl ether of di (or tri) ethylene glycol (however, the two alkyl groups of the dialkyl ether may be the same or different.)
(A-2) di (or tri) ethylene glycol in which one end is an alkyl ether and the other end is an alkyl ester (a-3) an alkoxyalkyl ester of a saturated or unsaturated fatty acid; The lubricating oil composition according to 1 or 2 above, wherein the component (B) is an α-olefin oligomer having a kinematic viscosity at 100 ° C. of 100 to 150 mm ² / s and / or a hydride of the α-olefin oligomer,
4). The lubricating oil composition according to any one of 1 to 3 above, wherein the component (B) is an α-olefin oligomer obtained using a metallocene catalyst and / or a hydride of the α-olefin oligomer,
5. Furthermore, any one of the above 1 to 4, further comprising as component (C) one or more lubricating oil additives selected from antioxidants, extreme pressure agents or antiwear agents, dispersants and metallic detergents A lubricating oil composition according to claim 1,
Is to provide.

According to the present invention, there is provided a lubricating oil composition having an extremely high viscosity index and a low traction coefficient, which is a fluid friction coefficient in an elastohydrodynamic lubricating region, and excellent in energy saving and fuel saving. be able to. Therefore, it is possible to provide a lubricating oil composition excellent in energy saving and fuel saving, in particular, capable of reducing power loss of a mechanical device having a rolling bearing and a gear.

The lubricating oil composition of the present invention contains (A) a low viscosity synthetic oil and (B) a high viscosity synthetic oil.

[(Component A) low viscosity synthetic oil]
The low-viscosity synthetic oil that is the component A of the present invention is required to be a compound having an ether bond in the molecule. The compound having an ether bond in the molecule may have at least one ether bond in the molecule and may have two or more. The number of preferred ether bonds in the molecule is 1 to 6, more preferably 1 to 4, and still more preferably 3 to 4.
Moreover, the compound which has an ether bond in the molecule | numerator of this invention should just have an ether bond, and also may have other bonds, for example, an ester bond.

The low viscosity synthetic oil of component A is required to be a compound having a kinematic viscosity at 40 ° C. of less than 10 mm ² / s. This is because the component A is used together with the high-viscosity synthetic oil (component B) in the lubricating oil composition, so that the kinematic viscosity of the composition is reduced to achieve energy saving and fuel saving. Therefore, the kinematic viscosity at 40 ° C. is preferably 9 mm ² / s or less, more preferably 8 mm ² / s or less, and further preferably 5 mm ² / s or less.
The lower limit of the kinematic viscosity at 40 ° C. of component A is not particularly limited, but is preferably 1 mm ² / s or more from the viewpoint of preventing evaporation loss of the lubricating oil composition, and 1.5 mm ² / S or more is more preferable.

The compound having an ether bond in the molecule of component A further comprises the ratio of the number of oxygen atoms and the number of carbon atoms constituting the compound (O / C ratio) and the kinematic viscosity at 40 ° C. of the compound (mm ² / s). ) And the following formula (1)
Kinematic viscosity at 40 ° C. ≦ 12-[(O / C ratio) × 30] (1)
It must be a low-viscosity synthetic oil that satisfies
A compound having an ether bond with an O / C ratio adjusted so as to satisfy the above formula (1) can exhibit good solubility and a low viscosity and a good viscosity index. In addition, in order to make the said effect more favorable, it is preferable to make the upper limit of the right side of said Formula (1) into 8.5.

Any component A can be used as the component A used in the present invention as long as it satisfies the above requirements. However, it is shown in the following (a-1) to (a-3) because it is easily available. It is preferable to use one or more compounds.
(A-1) Dialkyl ether of di (or tri) ethylene glycol (However, the two alkyl groups of the dialkyl ether may be the same or different.)
(A-2) di (or tri) ethylene glycol in which one end is an alkyl ether and the other end is an alkyl ester (a-3) an alkoxyalkyl ester of a saturated or unsaturated fatty acid (a-1) ) To (a-3), the alkyl ether, alkyl ester and alkoxyalkyl ester, and the number of carbon atoms of the fatty acid are selected so as to satisfy the definition of the kinematic viscosity at 40 ° C. and the above formula (1) of each compound. That's fine.
For example, examples of the alkyl ether include ethyl ether, propyl ether, butyl ether, hexyl ether, and hexyl butyl ether. Examples of these ether groups include monoether, diether, and triether. Of these, dibutyl ether is preferred. Examples of the alkyl ester include decanoic acid ester, octanoic acid ester, and nonanoic acid ester, and among them, octanoic acid ester is preferable. Examples of the alkoxyalkyl ester of a saturated or unsaturated fatty acid include palmitoleic acid butoxyethyl ester, oleic acid butoxyethyl ester, elaidic acid butoxyethyl ester, and among them, oleic acid butoxyethyl ester is preferable.

The A component can be used alone or in combination of two or more compounds having the corresponding ether bond. The content of the component A is preferably 20 to 90% by mass, more preferably 30 to 80% by mass, and particularly preferably 50 to 80% by mass based on the total amount of the A component and the B component described later. If content of A component is 20 mass% or more, the reduction effect of a traction coefficient will be recognized and the viscosity of a composition can be reduced simultaneously. On the other hand, if it is 90 mass% or less, a stable composition with good solubility can be obtained.
The low viscosity synthetic oil of component A preferably has a kinematic viscosity at 100 ° C. of a lower limit of 0.5 mm ² / s or more, more preferably 0.7 mm ² / s or more, and an upper limit of 3 preferably .0mm at ² / s or less, more preferably at most 2.0 mm ² / s, more preferably not more than 1.5 mm ² / s. By setting the 100 ° C. kinematic viscosity of the component A in such a range, it is possible to easily achieve both high viscosity index and low viscosity.

[(B component) high viscosity synthetic oil]
In the present invention, a hydrocarbon-based synthetic oil having a kinematic viscosity at 100 ° C. of 40 mm ² / s or more is used as the B component.
When the kinematic viscosity at 100 ° C. is less than 40 mm ² / s, a lubricating composition having a sufficient viscosity index may not be obtained. Therefore, the kinematic viscosity at 100 ° C. of the B component is preferably 50 mm ² / s or more, more preferably 80 mm ² / s or more, and further preferably 100 mm ² / s or more.
The upper limit of the kinematic viscosity at 100 ° C. is not particularly limited, but is preferably 150 mm ² / s or less and more preferably 130 mm ² / s or less from the viewpoint of preventing a decrease in shear stability. .
For these reasons, the B component preferably has a kinematic viscosity at 100 ° C. of 100 to 150 mm ² / s, and more preferably 100 to 130 mm ² / s.

In the present invention, the hydrocarbon-based high-viscosity synthetic oil (component B) having the above-mentioned kinematic viscosity is selected from α-olefin oligomers, α-olefin oligomer hydrides, and ethylene-propylene copolymer oligomers, Two or more kinds can be used. Among these, α-olefin oligomers and / or hydrides of α-olefin oligomers are preferable from the viewpoint of suppressing increase in viscosity at low temperatures.
The raw material for the α-olefin oligomer or the hydride of the α-olefin oligomer may be either linear or branched, and may be 1-octene, 1-nonene, 1-decene, One kind of α-olefin having 8 to 12 carbon atoms selected from -undecene and 1-dodecene can be used alone or in combination of two or more kinds.
Among these, α-olefin oligomers obtained using 1-decene as a raw material and / or hydrides of the α-olefin oligomers are preferably used.

A variety of polymerization (oligomerization) catalysts can be used for the polymerization of the α-olefin. Examples thereof include metallocene catalysts and so-called nonmetallocene catalysts such as boron trifluoride (BF ₃ ) and Ziegler catalysts.
Among these, α-olefin oligomers obtained using a metallocene catalyst and hydrogenated α-olefin oligomers obtained by further hydrogenation thereof are more preferable in view of high viscosity index.

As the metallocene catalyst, a complex having a conjugated carbon 5-membered ring containing a Group 4 element of the periodic table, that is, a metallocene complex and an oxygen-containing organoaluminum compound can be used in combination.
As the Group 4 element of the periodic table in the metallocene complex, titanium, zirconium and hafnium are used, and zirconium is particularly preferable. As the complex having a conjugated carbon 5-membered ring, a complex having a substituted or unsubstituted cyclopentadienyl ligand is generally used.
Examples of suitable metallocene complexes include bis (n-octadecylcyclopentadienyl) zirconium dichloride, bis (trimethylsilylcyclopentadienyl) zirconium dichloride, bis (tetrahydroindenyl) zirconium dichloride, bis [(t-butyldimethylsilyl ) Cyclopentadienyl] zirconium dichloride, bis (di-t-butylcyclopentadienyl) zirconium dichloride, (ethylidene-bisindenyl) zirconium dichloride, biscyclopentadienylzirconium dichloride, ethylidenebis (tetrahydroindenyl) zirconium dichloride and And bis [3,3 (2-methyl-benzindenyl)] dimethylsilanediylzirconium dichloride. These may be used individually by 1 type and may be used in combination of 2 or more type.

On the other hand, examples of the oxygen-containing organoaluminum compound include methylalumoxane, ethylalumoxane, and isobutylalumoxane. These may be used individually by 1 type and may be used in combination of 2 or more type.

The ethylene-propylene copolymer oligomer that can be used as the component B is not particularly limited, but a copolymer having an ethylene content of 10 to 90 mol%, preferably 20 to 80 mol% is usually used. Such a copolymer oligomer has a high viscosity index and good shear stability.

The content of the B component is preferably 80 to 10% by mass, more preferably 70 to 20% by mass, and particularly preferably 50 to 20% by mass based on the total amount of the A component and the B component. If the content of the B component is 10% by mass or more, a lubricating oil having a high viscosity index can be obtained, and if it is 80% by mass or less, a stable composition having good solubility can be obtained.
The total amount of the A component and the B component is preferably 70% by mass or more, more preferably 80% by mass or more, and further preferably 90% by mass or more in the lubricating oil composition.

[(C component) lubricating oil additive]
In the lubricating oil composition of the present invention, a lubricating oil additive can be further added as a C component to the composition containing the A component and the B component.
(C) Component lubricating oil additive includes (c-1) antioxidant, (c-2) extreme pressure agent or antiwear agent, (c-3) dispersant, and (c-4) metal system A detergent etc. are mentioned, It is preferable to mix | blend 1 type, or 2 or more types of lubricating oil additives chosen from these.

Examples of the antioxidant (c-1) include amine-based antioxidants, phenol-based antioxidants, and sulfur-based antioxidants.
Examples of amine-based antioxidants include dialkyl (alkyl group having 1 to 20 carbon atoms) diphenylamine, phenyl, such as 4,4′-dibutyldiphenylamine, 4,4′-dioctyldiphenylamine, and 4,4′-dinonyldiphenylamine. And naphthylamines such as -α-naphthylamine, octylphenyl-α-naphthylamine, and nonylphenyl-α-naphthylamine.

Examples of the phenolic antioxidant include monophenolic antioxidants such as 2,6-di-tert-butyl-4-methylphenol and 2,6-di-tert-butyl-4-ethylphenol, Examples thereof include diphenol antioxidants such as 4′-methylenebis (2,6-di-tert-butylphenol) and 2,2′-methylenebis (4-ethyl-6-tert-butylphenol).

Examples of the sulfur-based antioxidant include phenothiazine, pentaerythritol-tetrakis- (3-laurylthiopropionate), bis (3,5-tert-butyl-4-hydroxybenzyl) sulfide, thiodiethylenebis (3- (3,5-di-tert-butyl-4-hydroxyphenyl)) propionate, 2,6-di-tert-butyl-4- (4,6-bis (octylthio) -1,3,5-triazine-2 -Methylamino) phenol and the like.

These antioxidants may be used alone or in combination of two or more. The blending amount is usually selected in the range of 0.01 to 10% by mass, preferably 0.03 to 5% by mass, based on the total amount of the lubricating oil composition.

Examples of the extreme pressure agent or anti-wear agent of (c-2) include sulfur-based extreme pressure agents, phosphorus-based anti-wear agents, SP-based extreme pressure agents, zinc hydrocarbyl dithiophosphate, and thiazole-based extreme pressure agents. It is done.
Examples of sulfur-based extreme pressure agents include sulfurized fats and oils, sulfurized fatty acids, sulfurized esters, sulfurized olefins, dihydrocarbyl polysulfides, thiadiazole compounds, alkylthiocarbamoyl compounds, thiocarbamate compounds, thioterpene compounds, and dialkylthiodipropionate compounds. .
Examples of the phosphorus-based antiwear agent include phosphate esters such as phosphate esters, acid phosphate esters, phosphite esters, and acid phosphite esters, and amine salts of these phosphate esters.

The SP extreme pressure agent may be one containing sulfur and phosphorus in one compound, such as a thiophosphate such as triphenylthiophosphate and lauryl trithiophosphite. You may mix and use an extreme pressure agent. When a sulfur-based extreme pressure agent and a phosphorus-based extreme pressure agent are mixed, as the sulfur-based extreme pressure agent and the phosphorus-based extreme pressure agent, those exemplified for the sulfur-based extreme pressure agent and the phosphorus-based antiwear agent are respectively used. That's fine.

In addition, as zinc dihydrocarbyl dithiophosphate (ZnDTP), the hydrocarbyl group is a linear or branched alkyl group having 1 to 24 carbon atoms, or a linear or branched alkenyl group having 3 to 24 carbon atoms. A cycloalkyl group having 5 to 13 carbon atoms or a linear or branched alkylcycloalkyl group, an aryl group having 6 to 18 carbon atoms, or a linear or branched alkylaryl group, and 7 to 7 carbon atoms Any of 19 arylalkyl groups and the like may be used. The alkyl group or alkenyl group may be any of primary, secondary, and tertiary.

Examples of 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, 3,6-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-octyldithio) -1,2,3-thiadiazole 4,5-bis n- nonyldithio) -1,2,3-thiadiazole, 4,5-bis (1,1,3,3-tetramethylbutyl dithio) -1,2,3-thiadiazole, and the like.
One of these extreme pressure agents or antiwear agents may be used alone, or two or more thereof may be used in combination. The blending amount is usually selected in the range of 0.01 to 10% by mass, preferably 0.05 to 5% by mass, based on the total amount of the lubricating oil composition.

Examples of the dispersant (c-3) include imide dispersants, amide dispersants, and ester dispersants.
Specific examples include alkenyl group-substituted alkenyl succinimides having an average molecular weight of 1000 to 3500 and borides thereof, benzylamines, alkylpolyamines, and alkenyl succinates.
One of these dispersants may be used alone, or two or more thereof may be used in combination. The blending amount is usually selected in the range of 0.05 to 10% by mass, preferably 0.1 to 5% by mass, based on the total amount of the lubricating oil composition.

Examples of the metal detergent (c-4) include alkaline earth metal sulfonates such as Ca, Mg and Ba, alkaline earth metal phenates, alkaline earth metal salicylates, alkaline earth metal phosphonates and the like. These may be neutral, basic, or overbased.
These metal detergents may be used alone or in combination of two or more. The blending amount is usually selected in the range of 0.05 to 30% by mass, preferably 0.1 to 10% by mass, based on the total amount of the lubricating oil composition.

As the lubricating oil additive, in addition to the above, an oil agent, a rust inhibitor, a metal deactivator, a corrosion inhibitor, a pour point depressant, an antifoaming agent, and the like can be appropriately blended.

The total amount of the lubricating oil additive in the present invention is usually 1 to 20 parts by mass with respect to 100 parts by mass of the total amount of the component A and the component B. Preferably, it is 3 to 15 parts by mass.

[Other ingredients]
The lubricating oil composition of the present invention can contain a lubricating base oil as a component other than those described above, as long as the object of the present invention is not adversely affected.
Examples of the lubricating base oil include mineral oils having a kinematic viscosity at 100 ° C. of 10 mm ² / s or less, and synthetic oils such as α-olefin oligomers, polybutenes, and polyol esters. The blending amount is preferably in the range of 30% by mass or less based on the lubricating oil composition.

[Lubricating oil composition]
As described above, the lubricating oil composition of the present invention is a composition containing an A component, a B component, and, if necessary, a C component. The lubricating oil composition should have a viscosity index of 220 or more. Preferably, it is 240 or more, more preferably 260 or more. If the viscosity index is 220 or more, formation of an oil film at the sliding portion can be facilitated at high temperatures while achieving energy saving and fuel saving.
Further, the lubricating oil composition of the present invention preferably has a traction coefficient of 0.025 or less, and more preferably 0.020 or less. When the traction coefficient is 0.025 or less, the effect of reducing the fluid friction coefficient in the elastic fluid lubrication region is sufficiently exhibited.
Incidentally, the traction coefficient is a value measured by the valuation method described below.

Further, the kinematic viscosity of the lubricating oil composition of the present invention is not particularly limited, and may be appropriately selected depending on the use and use conditions of the lubricating oil composition.
For example, when the lubricating oil composition is a transmission oil for automobiles, the kinematic viscosity at 40 ° C. is preferably 25 mm ² / g or less, and the kinematic viscosity at 100 ° C. is preferably 6 mm ² / g or more.

The lubricating oil composition of the present invention is a lubricating oil that reduces power loss of a mechanical device having rolling bearings and gears as machine elements and contributes to energy and fuel savings. Industrial bearing oils, industrial gear oils, automobiles It is suitably used for gear oil for automobiles, transmission oil for automobiles, and the like.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
[Examples 1 to 12 and Comparative Examples 1 to 11]
A lubricating oil composition having the composition shown in Table 2 was prepared using the base material shown in Table 1, and the viscosity index, kinematic viscosity, solubility, and traction coefficient were measured. The lubricating oil composition was prepared by stirring and mixing the base material used in the composition at 60 ° C. for 30 minutes.
In addition, the additive used for the Example of Table 2 and the comparative example is a package of the compound shown in the content column of the additive of Table 1, and all are the packages of the same additive.
Moreover, the symbol of the base material shown in Table 1 and used in Table 2 indicates the classification as follows.
ET: Compound having an ether bond ETS: Compound having an ether bond and an ester bond ES: Compound having an ester bond PAO: α-olefin oligomer HV-PAO: High viscosity α-olefin oligomer EPO: Ethylene-propylene copolymer oligomer PB: Polybutene

Moreover, the property and performance of the lubricating oil composition were measured by the following methods.
<Method for measuring properties of lubricating oil composition>
(1) Kinematic viscosity Measured according to JIS K2283.
(2) Viscosity index Measured according to JIS K2283.
<Evaluation method of performance of lubricating oil composition>
(3) Solubility of lubricating oil composition After leaving the lubricating oil composition obtained by the above preparation method at room temperature for 8 hours, the appearance of the lubricating oil composition is visually observed to cause precipitation of insoluble matter. The presence or absence was confirmed.
The case where there was no precipitation of insoluble matter and good solubility was indicated as “OK”, and the case where precipitation of insoluble matter was observed and poor solubility was indicated as “NG”.

(4) Traction coefficient The traction coefficient was measured with the following tester and measurement conditions.
Testing machine: Mini Traction Machine (manufactured by PCS Instruments)
Measurement condition:
Ball: Diameter 19.05 mm, AISI 52100 bearing steel Disc: Diameter 50 mm, AISI 52100 bearing steel Rolling speed: 4.0 m / s
Load: 45N
Oil temperature: 40 ° C
Slip rate: 10%

Table 2 shows the following.
The lubricating oil composition containing the low-viscosity synthetic oil and the high-viscosity synthetic oil of the present invention has an extremely high viscosity index of 220 or more and an extremely small traction coefficient of 0.024 or less. Furthermore, these compositions have good solubility and are stable compositions (Examples 1 to 12).
In contrast, the low-viscosity synthetic oil is a compound having an ether bond that does not satisfy the formula (1), Comparative Examples 1 to 3, and the low-viscosity synthetic oil has a kinematic viscosity (40 ° C.) of 10 mm ² / s or more In Comparative Examples 3 and 7, or Comparative Examples 4 to 10 where the low-viscosity synthetic oil is not a compound having an ether bond, and Comparative Example 11 where the high-viscosity synthetic oil is not a compound defined by the present invention, a stable composition cannot be obtained. None of the objects of the present invention can be achieved, such as a large traction coefficient.

According to the present invention, there is provided a lubricating oil composition having an extremely high viscosity index and a low traction coefficient, which is a fluid friction coefficient in an elastohydrodynamic lubricating region, and excellent in energy saving and fuel saving. be able to. Therefore, in particular, it is excellent in energy saving and fuel saving that can reduce the power loss of a mechanical device having a rolling bearing and gears, and includes various kinds of industrial bearing oils, industrial gear oils, automotive gear oils, automotive shift base oils, and the like. It can be effectively used as a lubricating oil composition.

Claims

A lubricating oil composition comprising the following component (A) and component (B):
(A) a compound having an ether bond in the molecule and having a kinematic viscosity at 40 ° C. of less than 10 mm 2 / s, the ratio of the number of oxygen atoms and the number of carbon atoms constituting the compound (O / C ratio) and the compound The kinematic viscosity (mm 2 / s) at 40 ° C. of the following formula (1)
Kinematic viscosity at 40 ° C. ≦ 12-[(O / C ratio) × 30] (1)
Low viscosity synthetic oil that satisfies
(B) A hydrocarbon-based synthetic oil having a kinematic viscosity at 100 ° C. of 40 mm 2 / s or more, which is selected from α-olefin oligomers, α-olefin oligomer hydrides, and ethylene-propylene copolymer oligomers, or Two or more high viscosity synthetic oils.
The lubricating oil composition according to claim 1, wherein the component (A) is one or more compounds selected from the following (a-1) to (a-3).
(A-1) Dialkyl ether of di (or tri) ethylene glycol (however, the two alkyl groups of the dialkyl ether may be the same or different.)
(A-2) di (or tri) ethylene glycol in which one end is an alkyl ether and the other end is an alkyl ester (a-3) an alkoxyalkyl ester of a saturated or unsaturated fatty acid
The lubricating oil composition according to claim 1 or 2, wherein the component (B) is an α-olefin oligomer having a kinematic viscosity at 100 ° C of 100 to 150 mm 2 / s and / or a hydride of the α-olefin oligomer.
The lubricating oil composition according to any one of claims 1 to 3, wherein the component (B) is an α-olefin oligomer obtained using a metallocene catalyst and / or a hydride of the α-olefin oligomer.
The component (C) further comprises one or more lubricating oil additives selected from an antioxidant, an extreme pressure agent or an antiwear agent, a dispersant, and a metal detergent. A lubricating oil composition according to claim 1.