JP2019035047A - Mineral oil-based base oil and lubricant composition - Google Patents

Abstract

To provide a mineral oil-based base oil having a high flash point while having low viscosity and a lubricant composition capable of enhancing fuel-saving performance by further lowering viscosity, while having a high flash point.SOLUTION: A mineral oil-based base oil of the present invention has a kinematic viscosity of 4.0 mm/s or more and less than 6.0 mm/s at 40°C, has a kinematic viscosity of more than 1.5 mmand less than 2.0 mmat 100°C, and has a flash point of not lower than 140°C.SELECTED DRAWING: None

Description

  The present invention relates to a mineral oil base oil and a lubricating oil composition using the mineral oil base oil.

In recent years, lubricating oil compositions used as drive system oils such as automatic transmission oil (ATF), continuously variable transmission oil (CVTF), shock absorber oil (SAF), engine oil, hydraulic fluid, etc. Accordingly, various characteristics are required.
Since the characteristics of the lubricating oil composition are often greatly affected by the properties of the base oil used, the development of a base oil that can produce a lubricating oil composition that can exhibit the required characteristics is also widespread. Has been done.

For example, Patent Document 1 discloses that the flash point is 170 ° C. or higher, the kinematic viscosity at 40 ° C. is 9.0 to 14.0 mm ² / s, the viscosity index is 100 or more, and the 5 vol% distillation temperature in the distillation test is 310 ° C. As described above, hydrocarbon-based lubricating base oils having a pour point of −30 ° C. or less and an aromatic content (% C _A ) of 0.1 or less are described.
According to the description in Patent Document 1, since the lubricating base oil maintains a conventional viscosity and has a high flash point, the lubricating oil composition used at high temperatures such as power steering oil and transmission oil for automobiles. It is said that it is suitable for a thing.

JP 2004-182931 A

By the way, in recent years, a lubricating oil composition used as a drive system oil has been required to improve fuel-saving performance by further reducing viscosity while maintaining a high flash point and good safety.
The lubricating base oil described in Patent Document 1 is a high viscosity base oil having a kinematic viscosity at 40 ° C. of 9.0 mm ² / s or more, so that the fuel consumption performance is improved by reducing the viscosity of the lubricating oil composition. It is hard to say that it is a suitable base oil.
A general mineral base oil as described in Patent Document 1 tends to lower the flash point when the kinematic viscosity is lowered to lower the viscosity.
Therefore, a mineral base oil having a high flash point is demanded while the viscosity is lowered.

  The present invention provides a mineral base oil having a high flash point while having a low viscosity, and a lubricating oil capable of further improving fuel-saving performance by further reducing the viscosity while having a high flash point. An object is to provide a composition.

The present inventor has found that a mineral base oil having a flash point of not less than a predetermined value can be solved by adjusting the kinematic viscosity at 40 ° C. and 100 ° C. to a predetermined range and lowering the viscosity. Completed the invention. That is, the present invention provides the following [1] to [2].
[1] is less than the 4.0 mm ² / s or more kinematic viscosity 6.0 mm ² / s at 40 ° C., a kinematic viscosity of greater than 1.5 mm ² / s at 100 ° C., was less than 2.0 mm ² / s And
A mineral base oil having a flash point of 140 ° C. or higher.
[2] A lubricating oil composition comprising the mineral base oil according to [1] above.

  The mineral base oil of the present invention can have a high flash point while having a low viscosity. Therefore, the lubricating oil composition containing the mineral oil-based base oil of the present invention can be improved in fuel saving performance by further reducing the viscosity while having a high flash point.

[Properties of the mineral base oil of the present invention]
The mineral base oil of the present invention satisfies the following requirements (I) and (II).
Requirement (I): The kinematic viscosity at 40 ° C. is 4.0 mm ² / s or more and less than 6.0 mm ² / s, the kinematic viscosity at 100 ° C. exceeds 1.5 mm ² / s, and 2.0 mm ² / s. Is less than.
-Requirement (II): Flash point is 140 ° C or higher.
In this specification, the kinematic viscosity at 40 ° C. or 100 ° C. means a value measured in accordance with JIS K2283: 2000, and the flash point is in accordance with JIS K2265-4. ) Means the value measured by the method.

Generally, as the properties of mineral oil base oil, the lower the viscosity, the lower the flash point.
On the other hand, the mineral oil base oil of the present invention is a mineral oil system having a flash point adjusted to 140 ° C. or higher as defined in requirement (II) while being reduced in viscosity as defined in requirement (I). Base oil.
Therefore, by using the mineral base oil of the present invention, it is easy to obtain a lubricating oil composition that has a low flash point and has improved fuel economy when used as a drive system oil while having a high flash point. Can be manufactured.
Further, the mineral base oil of the present invention has a relatively small difference between the kinematic viscosity at 40 ° C. and the kinematic viscosity at 100 ° C. as defined in the requirement (I), and the temperature dependency of the viscosity is low. Therefore, by using the mineral oil base oil of the present invention, a lubricating oil composition having a small viscosity change due to temperature can be produced.

Kinematic viscosity at 40 ° C. of mineral base oil of the present invention _{(V 40)} is at 4.0 mm ² / s or more, preferably 4.2 mm ² / s or more, more preferably 4.3 mm ² / s or more , more preferably 4.4 mm ² / s or more, even more preferably 5.0 mm ² / s or more.
The kinematic viscosity _{(V 40)} is less than 6.0 mm ² / s, preferably 5.95 mm ² / s or less, more preferably 5.9 mm ² / s or less, more preferably 5.8 mm ² / s or less.

The mineral base oil of the present invention has a kinematic viscosity (V ₁₀₀ ) at 100 ° C. of more than 1.5 mm ² / s, preferably 1.6 mm ² / s or more, more preferably 1.7 mm ² / s or more. More preferably, it is 1.75 mm < ² > / s or more, More preferably, it is 1.8 mm < ² > / s or more.
The kinematic viscosity _{(V 100)} is less than 2.0 mm ² / s, preferably 1.95 mm ² / s or less, more preferably 1.90 mm ² / s or less, more preferably 1.88 mm ² / s or less.
The mineral base oil of the present invention is a mineral oil whose viscosity index measured according to JIS K2283: 2000 cannot be calculated.

  The flash point of the mineral base oil of the present invention is 140 ° C. or higher, preferably 142 ° C. or higher, more preferably 144 ° C. or higher, still more preferably 146 ° C. or higher, still more preferably 150 ° C. or higher. In addition, it is usually 180 ° C. or lower.

The 10 vol% distillation temperature of the mineral base oil measured according to the gas chromatographic distillation test method of JIS K2254 of the mineral base oil of one aspect of the present invention is preferably 250 ° C or higher, more preferably Is at least 255 ° C, more preferably at least 280 ° C, even more preferably at least 285 ° C, and usually at most 305 ° C.
In addition, the 90 vol% distillation temperature of the mineral base oil measured according to the gas chromatographic distillation test method of JIS K2254 of the mineral base oil of one aspect of the present invention is preferably 320 ° C or higher. Preferably it is 330 degreeC or more, More preferably, it is 340 degreeC or more, More preferably, it is 350 degreeC or more, and it is 365 degrees C or less normally.

The aniline point of the mineral base oil of one embodiment of the present invention is preferably 70 ° C or higher, more preferably 80 ° C or higher, still more preferably 85 ° C or higher, still more preferably 90 ° C or higher, particularly preferably 92 ° C or higher. Moreover, it is 110 degrees C or less normally.
Mineral oil base oils having an aniline point of 70 ° C. or higher tend to have a high paraffin content and a low aromatic content and are likely to have a high flash point.
In addition, in this specification, an aniline point means the value measured based on JISK2256 (U-shaped pipe method).

The density at 15 ℃ aspect mineral base oil of the present invention, preferably 0.860 g / cm ³ or less, more preferably 0.850 g / cm ³ or less, more preferably 0.840 g / cm ³ or less, More preferably, it is 0.830 g / cm ³ or less, particularly preferably 0.827 g / cm ³ or less, and usually 0.800 g / cm ³ or more.
If the mineral base oil having a density of 0.860 g / cm ³ or less while satisfying the requirements (I) and (II), the mineral base oil having a lower temperature dependency of viscosity and a higher flash point is obtained. can do.
In the present specification, the density at 15 ° C. is a value measured in accordance with JIS K2249.

The paraffin content (% C _P ) of the mineral base oil of one embodiment of the present invention is preferably 60 to 80, more preferably 62 to 77, still more preferably 63 to 75, and still more preferably 65 to 72. .

The naphthene content (% C _N ) of the mineral base oil of one embodiment of the present invention is preferably 20 to 40, more preferably 23 to 38, still more preferably 26 to 36, and still more preferably 28 to 35. .

The aromatic content (% C _A ) of the mineral base oil of one embodiment of the present invention is preferably less than 2.0, more preferably less than 1.5, and still more preferably less than 1.2.

In this specification, the paraffin content (% C _P ), the naphthene content (% C _N ), and the aromatic content (% C _A ) are measured by ASTM D-3238 ring analysis (ndM method). The ratio (percentage) of the paraffin content, naphthene content, and aromatic content.

The mineral oil base oil of one embodiment of the present invention preferably further satisfies the following requirement (III).
Requirement (III): Complex viscosity between two points of −10 ° C. and −25 ° C. measured under the conditions of an angular velocity of 6.3 rad / s and a strain of 0.1 to 100% using a rotary rheometer. The temperature gradient Δ | η * | (hereinafter, also simply referred to as “complex viscosity temperature gradient Δ | η * |”) is 60 Pa · s / ° C. or less.
In addition, when the mineral base oil of 1 aspect of this invention is a mixed oil which combined 2 or more types of mineral oil, the said mixed oil should just satisfy said requirements (III).

The “strain amount” described in the requirement (III) is a value that is appropriately set in accordance with the temperature in the range of 0.1 to 100%.
In addition, the above-mentioned “temperature gradient Δ | η * | of the complex viscosity” indicates that the value of the complex viscosity η * at −10 ° C. and the value of the complex viscosity η * at −25 ° C. are independently or − Measured while continuously changing the temperature from 10 ° C to -25 ° C or from -25 ° C to -10 ° C, and when the value was placed on the coordinate plane of temperature-complex viscosity, two points of -10 ° C and -25 ° C It is a value showing the amount of change per unit of complex viscosity (absolute value of slope). More specifically, it means a value calculated from the following calculation formula (f1).
Calculation formula (f1): temperature gradient Δ | η * | = | ([complex viscosity η * at −25 ° C.] − [Complex viscosity η *] at −10 ° C.) / (− 25 − (− 10) )) ｜
That is, the “temperature gradient Δ | η * | of complex viscosity” defined in the requirement (III) indicates the change over time with the temperature lowered as the low temperature characteristic of the mineral oil.

By the way, since mineral oil contains a wax component, when the temperature of the mineral oil is gradually lowered, the wax component in the mineral oil precipitates to form a gel-like structure. The wax content varies depending on the structure of paraffin or the like. Since the gel-like structure of the wax is easily broken, the viscosity of the mineral oil is changed by a mechanical action. Conventionally, the low-temperature viscosity characteristic parameters used in the past did not take into account the precipitation of such a wax component.
On the other hand, the “temperature gradient Δ | η * | of complex viscosity” prescribed in requirement (III) takes into account the precipitation rate of the wax contained in mineral oil and accurately evaluates the low-temperature viscosity characteristics of mineral oil. It is a possible index.

Mineral oil base oil that satisfies requirement (III) has a complex viscosity temperature gradient Δ | η * | of 60 Pa · s / ° C or less and is adjusted so as not to increase the precipitation rate of the wax component. It is difficult to cause an increase in the viscosity and the temperature dependency of the viscosity is lower while the viscosity is lower.
Therefore, by using the mineral oil base oil, it is possible to produce a lubricating oil composition that is excellent in fuel saving performance and has a smaller viscosity change due to temperature.

From the above viewpoint, the temperature gradient Δ | η * | of the complex viscosity specified in the requirement (III) is preferably 30 Pa · s / ° C. or less, more preferably 5 Pa · s / ° C. or less, and still more preferably 1.0 Pa. · S / ° C or less, more preferably 0.1 Pa · s / ° C or less, still more preferably 0.01 Pa · s / ° C or less, particularly preferably 0.0050 Pa · s / ° C or less.
Further, the temperature gradient Δ | η * | of the complex viscosity specified in the requirement (III) is preferably 0.0001 Pa · s / ° C. or more, more preferably 0.0005 Pa · s / ° C. or more, and further preferably 0.0010 Pa. · S / ° C or more, more preferably 0.0018 Pa · s / ° C or more.

<Preparation Example of Mineral Oil Base Oil of the Present Invention>
The mineral base oil of the present invention that satisfies the above requirements (I) to (III) is related to the selection of the raw material oil used as the raw material of the mineral oil base oil and the method for producing the mineral oil base oil using the raw material oil. It can prepare easily by considering the matter shown below suitably. That is, the mineral base oil of the present invention is preferably a mineral oil obtained by subjecting the following raw material oil to the following purification treatment.
In addition, the following matters are examples of the preparation method, and the preparation can also be performed by considering other matters.

[Selection of raw oil]
The raw material for the mineral base oil of the present invention is referred to as raw material oil. Examples of the raw oil include atmospheric residual oil obtained by atmospheric distillation of crude oil such as paraffinic mineral oil, intermediate mineral oil, and naphthenic mineral oil; distillate oil obtained by vacuum distillation of the atmospheric residual oil And the like.
These feedstock oils may be used alone or in combination of two or more.

  From the viewpoint of preparing a mineral oil base oil having a low flash viscosity as defined in the requirement (I) but having a low viscosity dependency due to temperature and having a high flash point as defined in the requirement (II). The oil preferably contains a bottom fraction obtained by hydrocracking heavy gas oil.

The kinematic viscosity of the raw material oil at 40 ° C. is preferably 6.0 to 25.0 mm ² / s, more preferably 8.0 to 22.0 mm ² / s, and still more preferably 10.0 to 20.0 mm ^2. / S, more preferably 12.0 to 18.0 mm ² / s.
The kinematic viscosity of the raw material oil at 100 ° C. is preferably 2.0 to 6.0 mm ² / s, more preferably 2.3 to 5.5 mm ² / s, still more preferably 2.5 to 5.0 mm ^2. / S, more preferably 3.0 to 4.8 mm ² / s.
The viscosity index of the raw material oil is preferably 100 or more, more preferably 110 or more, still more preferably 120 or more, and still more preferably 130 or more.

  The flash point of the raw material oil is preferably 140 to 280 ° C, more preferably 140 to 250 ° C, and still more preferably 140 to 220 ° C.

The 10% by volume distillation temperature of the raw material oil measured according to the gas chromatographic distillation test method of JIS K2254 is preferably 270 ° C. or higher, more preferably 285 ° C. or higher, still more preferably 300 ° C. or higher, and even more. Preferably it is 320 degreeC or more, and is 400 degrees C or less normally.
The 90% by volume distillation temperature of the raw material oil measured according to the gas chromatographic distillation test method is preferably 370 ° C. or higher, more preferably 385 ° C. or higher, more preferably 400 ° C. or higher, and still more. Preferably it is 420 degreeC or more, Most preferably, it is 440 degreeC or more, and is 600 degrees C or less normally.

The mass average molecular weight (Mw) of the raw material oil is preferably 150 to 500, more preferably 180 to 450, and still more preferably 200 to 400.
In addition, in this specification, the mass mean molecular weight (Mw) of raw material oil means the value measured based on ASTM D2502.

The mineral base oil of the present invention can be obtained by taking out a low-viscosity fraction by distillation after performing a refining treatment as shown below, while using such a raw material oil having a relatively high kinematic viscosity. it can.
By subjecting the above-mentioned raw material oil to a refining treatment under specific conditions, a mineral oil base oil having a high flash point can be prepared even for a low-viscosity fraction.

[Method for producing mineral base oil of the present invention]
The mineral base oil of one embodiment of the present invention is preferably obtained by subjecting the above-mentioned raw material oil to a purification treatment. In addition, it is preferable that the kind of refinement | purification process and refinement | purification conditions are set suitably according to the kind of feedstock to be used.

The purification treatment preferably includes one or more treatments selected from solvent removal, solvent extraction, solvent dewaxing, catalytic dewaxing, hydroisomerization dewaxing, and hydrofinishing, and at least hydroisomerization. More preferably, a dewaxing treatment is included, and at least a hydroisomerization dewaxing treatment and a hydrofinishing treatment are more preferably included.
Hereinafter, “hydroisomerization dewaxing treatment” and “hydrofinishing treatment” will be described.

(Hydroisomerization dewaxing treatment)
As described above, the hydroisomerization dewaxing process is a purification process performed for the purpose of isomerization in which a linear paraffin contained in a raw material oil is converted into a branched-chain isoparaffin.
In addition, the aromatic isomerization and dewaxing treatment can open the aromatic component to form a paraffin component, or remove impurities such as a sulfur component and a nitrogen component.
By this hydroisomerization treatment, the ratio of branched-chain isoparaffins increases, viscosity dependency due to temperature is low, and a mineral base oil having a high flash point can be prepared.
That is, even if a low-viscosity fraction is taken out during distillation, a high flash point can be obtained, so that a mineral base oil that satisfies the requirements (I) to (II) can be obtained.

  In addition, the presence of linear paraffin in the raw material oil is one of the factors that increase the value of the temperature gradient Δ | η * | Therefore, in this treatment, it is preferable to isomerize linear paraffin into branched isoparaffin and adjust the value of the temperature gradient Δ | η * | of the complex viscosity to be low.

The hydroisomerization dewaxing treatment is preferably performed in the presence of a hydroisomerization dewaxing catalyst.
Examples of the hydroisomerization dewaxing catalyst include a carrier such as silica aluminophosphate (SAPO) and zeolite, nickel (Ni) and tungsten (W), nickel (Ni) and molybdenum (Mo), and cobalt (Co). And a catalyst carrying a metal oxide of a composite metal material such as molybdenum (Mo) or a noble metal such as platinum (Pt) or lead (Pb).

  The hydrogen partial pressure in the hydroisomerization dewaxing treatment is preferably 2.0 to 30 MPa, more preferably 2.5 to 27 MPa, from the viewpoint of a mineral oil base oil that satisfies the requirements (I) to (III). More preferably, it is 3.0-25 MPa, More preferably, it is 3.5-22 MPa.

The reaction temperature in the hydroisomerization dewaxing treatment is higher than the reaction temperature in the general hydroisomerization dewaxing treatment from the viewpoint of a mineral base oil satisfying the requirements (I) to (III). It is preferably set, specifically, preferably 250 to 400 ° C, more preferably 275 to 380 ° C, still more preferably 280 to 370 ° C, and still more preferably 285 to 360 ° C.
Since the reaction temperature is high, isomerization of linear paraffin to branched isoparaffin can be promoted, and in particular, preparation of a mineral oil-based base oil that satisfies the requirements (II) and (III) is facilitated. .

In addition, the liquid hourly space velocity (LHSV) in the hydroisomerization dewaxing treatment is preferably 5.0 hr ⁻¹ or less, more preferably from the viewpoint of a mineral oil base oil that satisfies the requirements (I) to (III). Is 3.0 hr ⁻¹ or less, more preferably 2.0 hr ⁻¹ or less, and even more preferably 1.5 hr ⁻¹ or less.
Further, from the viewpoint of improving productivity, LHSV in the hydroisomerization dewaxing treatment is preferably 0.1 hr ⁻¹ or more, more preferably 0.2 hr ⁻¹ or more.

The feed rate of the hydrogen gas in the hydroisomerization dewaxing process, the raw material Oil 1 kiloliter supplied, preferably 100 to 2000 nm ^3, more preferably 200 to 1500 nm ^3, more preferably at 250～1000Nm ³ is there.

(Hydrogen finishing)
The hydrofinishing treatment is a purification treatment performed for the purpose of complete saturation of aromatic components contained in the raw material oil and removal of impurities such as sulfur and nitrogen.

The hydrofinishing treatment is preferably performed in the presence of a hydrogenation catalyst.
As a hydrogenation catalyst, for example, a composite material of silica and alumina, an amorphous material such as alumina, or a crystalline carrier such as zeolite, nickel (Ni) and tungsten (W), nickel (Ni) and molybdenum (Mo), Examples thereof include a metal oxide of a composite metal material such as cobalt (Co) and molybdenum (Mo), and a catalyst supporting a noble metal such as platinum (Pt) or lead (Pb).

  The hydrogen partial pressure in the hydrofinishing treatment is preferably set higher than the pressure in a general hydrotreatment from the viewpoint of a mineral oil base oil that satisfies the requirements (II) and (III), Specifically, it is preferably 16 MPa or more, more preferably 17 MPa or more, still more preferably 18 MPa or more, and preferably 30 MPa or less, more preferably 22 MPa or less.

  The reaction temperature in the hydrofinishing treatment is preferably 200 to 400 ° C, more preferably 250 to 350 ° C, and still more preferably 280 to 330, from the viewpoint of a mineral oil base oil that satisfies the requirements (II) and (III). ° C.

The liquid hourly space velocity (LHSV) in the hydrofinishing treatment is preferably 5.0 hr ⁻¹ or less, more preferably 2.0 hr ⁻ , from the viewpoint of a mineral base oil satisfying the requirements (II) and (III). ¹ or less, more preferably not more 1.0 hr ^-1 or less, from the viewpoint of productivity, preferably 0.1 hr ^-1 or more, more preferably 0.2 hr ^-1 or more, more preferably 0.3 hr ^-1 That's it.

The supply ratio of hydrogen gas in the hydrofinishing treatment is preferably 100 to 2000 Nm ³ , more preferably 200 to 100 liters per 1 liter of oil to be supplied (refined oil subjected to hydroisomerization dewaxing treatment). 1500 Nm ³ , more preferably 250 to 1100 Nm ³ .

(Post-processing)
After completion of the above-described refining treatment, the obtained refined oil is appropriately subjected to distillation under reduced pressure or simple distillation, and by collecting a fraction whose kinematic viscosity at 40 ° C. falls within the range specified in the requirement (I), The mineral base oil of the present invention can be obtained. That is, the mineral base oil of the present invention, which is a recovered fraction, has a high flash point while being reduced in viscosity as defined in requirement (I).
The distillation conditions (pressure, temperature, time, etc.) are adjusted as appropriate so that the kinematic viscosity of the resulting mineral base oil at 40 ° C. and 100 ° C. is within the range specified in requirement (I). Is done.

[Lubricating oil composition]
The lubricating oil composition of the present invention contains the mineral oil base oil of the present invention described above, but may contain a synthetic oil together with the mineral oil base oil.

Examples of the synthetic oil include an α-olefin homopolymer or an α-olefin copolymer (for example, an α-olefin copolymer having 8 to 14 carbon atoms such as an ethylene-α-olefin copolymer). Poly α-olefins; isoparaffins; polyol esters, dibasic acid esters (for example, ditridecyl glutarate), tribasic acid esters (for example, 2-ethylhexyl trimellitic acid), phosphoric acid esters, etc .; polyphenyl ether Synthetic oils obtained by isomerizing wax (GTL wax) produced by the Fischer-Tropsch method or the like.
These synthetic oils may be used alone or in combination of two or more.

  In the lubricating oil composition of one aspect of the present invention, the content of the synthetic oil is preferably 0 to 30 mass with respect to 100 mass parts of the total amount of the mineral oil base oil of the present invention contained in the lubricating oil composition. Parts, more preferably 0 to 20 parts by mass, still more preferably 0 to 10 parts by mass, and still more preferably 0 to 5 parts by mass.

  The content of the mineral base oil of the present invention contained in the lubricating oil composition of one embodiment of the present invention is usually 60% by mass or more, preferably based on the total amount (100% by mass) of the lubricating oil composition. 70% by mass or more, more preferably 80% by mass or more, still more preferably 85% by mass or more, still more preferably 90% by mass or more, and usually 100% by mass or less, more preferably 99.99% by mass or less, still more preferably. Is 99 mass% or less.

In addition, the lubricating oil composition of the present invention may further contain a generally used additive for lubricating oil as necessary, as long as the effects of the present invention are not impaired.
Examples of such lubricant additives include pour point depressants, viscosity index improvers, metal detergents, dispersants, antiwear agents, extreme pressure agents, antioxidants, antifoaming agents, and friction modifiers. , Rust preventives, metal deactivators and the like.
As the lubricant additive, a commercially available additive package containing a plurality of additives may be used.
Moreover, you may use the compound (For example, the compound which has a function as an antiwear agent and an extreme pressure agent) which has two or more functions as said additive.
Furthermore, each additive for lubricating oil may be used alone or in combination of two or more.

  Each content of these lubricating oil additives can be appropriately adjusted according to the type of the additive within a range not impairing the effects of the present invention, but the total amount of the lubricating oil composition (100% by mass). ) On the basis, it is usually 0.001 to 15% by mass, preferably 0.005 to 10% by mass, and more preferably 0.01 to 8% by mass.

<Use of lubricating oil composition>
Since the lubricating oil composition of the present invention contains the mineral base oil of the present invention described above, it has a high flash point and excellent fuel economy performance.
Therefore, the lubricating oil composition of the present invention is, for example, a drive system oil such as an automatic transmission oil (ATF), a continuously variable transmission oil (CVTF), a shock absorber oil (SAF), a power steering oil, and an electric motor cooling oil. Engine oil, hydraulic fluid, turbine oil, compressor oil, machine tool lubricant, cutting oil, gear oil, fluid bearing oil, rolling bearing oil, and the like.
In particular, in recent years, electric vehicles and hybrid vehicles have been required to be smaller and lighter by packaging a transmission and an electric motor. In addition to the performance required for transmission oil, there is a need for cooling oil for the electric motor. Therefore, there is a need for a lubricating oil composition that also has a cooling property.
Since the lubricating oil composition of the present invention has a low viscosity, it also has cooling performance and is suitable for use in such electric vehicles and hybrid vehicles.

That is, this invention can also provide the usage method of the lubricating oil composition of following (1).
(1) A lubricating oil composition containing the mineral oil base oil of the present invention is converted into a power transmission device (automatic transmission, continuously variable transmission, shock absorber, power steering, electric motor, etc.), engine, hydraulic actuator, turbine, A method of using a lubricating oil composition used for lubrication of any one of a compressor, a machine tool, a cutting machine, a gear, a fluid bearing, and a rolling bearing.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples. In addition, the measuring method or evaluation method of various physical properties is as follows.

(1) Kinematic viscosity at 40 ° C. and 100 ° C., viscosity index Measured and calculated according to JIS K2283: 2000.
(2) Flash point Measured by the Cleveland open method (COC) method in accordance with JIS K2265-4.
(3) Aromatic content (% C _A ), naphthene content (% C _N ), paraffin content (% C _P )
Measured by ASTM D-3238 ring analysis (ndM method).
(4) Density at 15 ° C. Measured according to JIS K2249.
(5) Refractive index at 20 ° C. Measured according to JIS K0062.
(6) 10 volume% distillation temperature, 90 volume% distillation temperature It measured based on the gas chromatographic distillation test method of JISK2254.
(7) Aniline point Measured according to JIS K2256 (U-tube method).
(8) Mass average molecular weight (Mw)
Measured according to ASTM D2502.

(9) Temperature gradient Δ | η * | of the complex viscosity between two points of −25 ° C. and −10 ° C.
Using a rheometer “Physica MCR 301” manufactured by Anton Paar, the following procedure was used.
First, a mineral oil base oil to be measured was inserted into a cone plate (diameter 50 mm, inclination angle 1 °) adjusted to a measurement temperature of −25 ° C. or −10 ° C., and held at the same temperature for 10 minutes. At this time, attention was paid not to give distortion to the inserted solution.
Then, at a measurement temperature of −25 ° C. or −10 ° C., vibration was performed under the conditions of a value appropriately set according to the measurement temperature within an angular velocity of 6.3 rad / s and a strain amount of 0.1 to 100%. In the mode, the complex viscosity η * at −25 ° C. or −10 ° C. was measured.
Based on the calculation formula (f1), “temperature gradient Δ | η * | of complex viscosity” was calculated from the value of complex viscosity η * at −25 ° C. and −10 ° C.

Example 1
(1) Properties of feedstock The feedstock (I) having various properties described in Table 1 was used.
The feedstock oil (I) includes a bottom fraction obtained by hydrocracking heavy gas oil with a hydrocracking apparatus.

(2) Production of mineral oil-based base oil (1) After dewaxing the raw material oil (I) shown in Table 1, using a platinum-zeolite-based catalyst (a catalyst in which platinum is supported on zeolite as a carrier), Hydroisomerization under the conditions of a reaction temperature of 287 ° C., a hydrogen partial pressure of 4 MPa, a supply amount ratio of hydrogen to the feedstock (I) [hydrogen / feedstock (I)] of 422 Nm ^{3 /} kL, LHSV 1.1 hr ⁻¹ A dewaxing treatment was performed to obtain a refined oil (i).
Next, the obtained refined oil (i) was subjected to reaction using a nickel / tungsten-alumina catalyst (a catalyst in which nickel and tungsten are supported on alumina as a support), a reaction temperature of 290 ° C., a hydrogen partial pressure of 18.5 MPa, hydrogen and Hydrofinishing treatment was performed under the conditions of the supply ratio [hydrogen / refined oil (i)] to refined oil (i) of 1000 Nm ^{3 /} kL, LHSV 0.6 hr ⁻¹ to obtain refined oil (i-1). It was.
Then, the refined oil (i-1), distillation under reduced pressure, kinematic viscosity 4.0 mm ² / s or more 6.0 mm ² / in the range of less than s fractions were collected at 40 ° C., and further single distillation A mineral oil base oil (1) was obtained.
Various properties of the mineral base oil (1) are shown in Table 2.

From Table 2, the mineral oil base oil (1) produced in Example 1 has a low flash point and a high flash point of 140 ° C. or higher.
Therefore, it is considered that the lubricating oil composition using this mineral oil-based base oil (1) can be improved in fuel saving performance by further reducing the viscosity while having a high flash point.

Claims (9)

Less than kinematic viscosity of 4.0 mm ² / s or more 6.0 mm ² / s at 40 ° C., a kinematic viscosity at 100 ° C. is a beyond less than ^{2.0mm 2 / s 1.5mm 2 / s} , and,
A mineral base oil having a flash point of 140 ° C. or higher.   Temperature gradient Δ | η * of the complex viscosity between two points of −10 ° C. and −25 ° C. measured under the conditions of an angular velocity of 6.3 rad / s and a strain of 0.1 to 100% using a rotary rheometer. The mineral oil base oil according to claim 1, wherein | is 60 Pa · s / ° C. or less. The raw material oil of the mineral oil base oil has a kinematic viscosity at 40 ° C. of 6.0 to 25.0 mm ² / s, and the kinematic viscosity of the raw material oil at 100 ° C. is 2.0 to 6.0 mm ² / s. The mineral base oil according to claim 1 or 2.   Measured according to the gas chromatographic distillation test method of JIS K2254, the 10% by volume distillation temperature of the feedstock is 270 ° C. or higher, and the 90% by volume distillation temperature of the feedstock is 370 ° C. or higher. The mineral oil base oil according to claim 3.   The mineral oil base oil according to claim 3 or 4, wherein the feedstock oil includes a bottom fraction obtained by hydrocracking heavy gas oil.   The mineral base oil according to any one of claims 3 to 5, wherein the raw oil is obtained through hydroisomerization dewaxing treatment. The mineral base oil according to any one of claims 1 to 6, wherein the aromatic content (% C _A ) is less than 2.0.   A lubricating oil composition comprising the mineral base oil according to any one of claims 1 to 7.   9. The drive system oil, engine oil, hydraulic fluid, turbine oil, compressor oil, machine tool lubricant, cutting oil, gear oil, fluid bearing oil, and rolling bearing oil are used as claimed in claim 8. Lubricating oil composition.