JP2023123047A - Lubricant composition - Google Patents

Abstract

To provide a lubricant composition which can excel in extreme pressure performance based on seizure resistance and wear preventive properties and low-temperature fluidity, can have a high viscosity index and can improve fuel-saving performance and gear durability.SOLUTION: There is provided a lubricant composition which comprises a lubricant base oil containing a base oil (A): a specific mineral oil-based base oil and a base oil (B): a specific wax isomerized base oil, wherein the content of the base oil (A) in the lubricant base oil is 45 mass% or more, the content of the base oil (B) in the lubricant base oil is 10 mass% or more and the kinematic viscosity of the lubricant oil base oil at 100°C is 7.00 mm2/s or more.SELECTED DRAWING: None

Description

The present invention relates to lubricating oil compositions.

Lubricating oil compositions are used in various fields, and have been applied, for example, to applications such as internal combustion engines such as gasoline engines and diesel engines, and gear devices. Various types of lubricating oil compositions have heretofore been studied in order to exhibit performance suitable for these uses.

For example, Japanese National Publication of International Patent Application No. 2009-533497 (Patent Document 1) discloses a technique related to gear lubricating oil, and in Example 7 thereof, a mixture of two specific waxes is hydrogenated, isomerized, and dewaxed. 75W-90 grade lubricating oil composition comprising 39.9 wt. It is

However, the conventional lubricating oil composition as described in Patent Document 1 has high extreme pressure performance, high viscosity index, and excellent low temperature fluidity, and improves fuel saving performance and gear durability. It wasn't enough in terms of making it work.

In the SAE J306 Standard (automotive gear oils) viscosity standards before 2005, since there is no provision for kinematic viscosity (minimum viscosity) after shearing, lubricating oil compositions of grade 75W-85 or higher (e.g., gear oil composition), the base oil viscosity was set low to satisfy the low-temperature viscosity standard of 75 W (BF viscosity -40°C: 150,000 mPa·s or less). However, if the low-temperature viscosity standard of 75 W is satisfied by setting the base oil viscosity low, there is a concern that gear fatigue durability may be greatly reduced due to the low base oil viscosity. Therefore, conventional lubricating oil compositions of grade 75W-85 or higher (for example, gear oil compositions), which meet the low-temperature viscosity standard of 75W by setting the base oil viscosity low, are currently not fuel efficient. It is not applied to the intended large cargo and passenger cars. There are also gear oils in the market that use all synthetic oils (such as PAO) as the base oil, but from the viewpoint of cost and durability reliability, they are not popular.

Japanese Patent Publication No. 2009-533497

The present invention has been made in view of the above-mentioned problems of the prior art, and can be made excellent in extreme pressure performance based on seizure resistance and wear resistance, and low temperature fluidity. An object of the present invention is to provide a lubricating oil composition that can have a viscosity index and can improve fuel economy performance and gear durability.

The present inventors have made intensive studies to achieve the above object, and as a result, the lubricating oil composition is a lubricating base oil containing the following base oils (A) to (B) (base oil composition: mixed base oil ), the content of the base oil (A) in the lubricating base oil is 45% by mass or more, and the content of the base oil (B) in the lubricating base oil is 10 mass% or more, and the kinematic viscosity at 100 ° C. of the lubricating base oil is 7.00 mm ^/ s or more, so that the resulting lubricating oil composition has anti-seizure and anti-wear properties. It can be made excellent in extreme pressure performance and low temperature fluidity as a standard, and it can be made to have a high viscosity index, and it is possible to improve fuel saving performance and gear durability. and completed the present invention.

That is, the lubricating oil composition of the present invention comprises the following base oils (A) to (B):
(A) a mineral base oil having a kinematic viscosity at 100° C. of 10 to 40 mm ² /s and a sulfur content of 0.3 to 2.0% by mass;
(B) a wax isomerized base oil having a kinematic viscosity at 100°C of 1.5 to 3.0 mm ² /s, a viscosity index of 120 or more and a pour point of -30°C or less;
Containing a lubricating base oil containing
The content of the base oil (A) in the lubricating base oil is 45% by mass or more,
The content of the base oil (B) in the lubricating base oil is 10% by mass or more, and
The kinematic viscosity at 100° C. of the lubricating base oil is 7.00 mm ² /s or more,
It is characterized by In this specification, each group in the descriptions "content of the base oil (A) in the lubricating base oil" and "content of the base oil (B) in the lubricating base oil" The "content" of any oil is the mass ratio (mass-based content ratio) of each base oil calculated based on the total mass of the lubricating base oil (base oil composition) (total amount of lubricating base oil) means. Further, in this specification, with respect to the base oils (A) to (B), the "sulfur content" in each base oil is based on the total mass of the base oil, and the sulfur contained in the base oil ( S) mass ratio (mass ratio in terms of sulfur atom (unit: mass %)), and its value can be measured according to ASTM D4951. Furthermore, "kinematic viscosity at 100°C" as used herein means the kinematic viscosity at 100°C defined in JIS K 2283-2000. Further, the term "viscosity index" as used herein means a viscosity index measured according to JIS K 2283-2000. The term "pour point" as used herein means the pour point measured according to JIS K 2269-1987.

Further, in the lubricating oil composition of the present invention, the base oil (B) has a wax isomerism having a %C _P of 85 or more, a %C _N of 2 to 15, and a %C _A of 3 or less. It is preferably a modified base oil. Further, in the lubricating oil composition of the present invention, in accordance with JPI-5S-29-88, ultrasonic waves are applied under the conditions of frequency: 10 kHz, vibrator amplitude: 28 μm, and irradiation time: 10 hours. When performing an irradiation shear stability test and measuring and comparing the kinematic viscosity at 100 ° C. of the lubricating oil composition before and after the ultrasonic irradiation, the lubricating oil composition at 100 ° C. by the ultrasonic irradiation The kinematic viscosity reduction rate is preferably 10% or less. Furthermore, in the lubricating oil composition of the present invention, the Brookfield viscosity at -40°C of the lubricating oil composition is preferably 150,000 mPa·s or less. Moreover, in the lubricating oil composition of the present invention, it is preferable that the lubricating oil composition is a gear oil composition. The lubricating oil composition of the present invention may also conform to the viscosity grade 75W-85 of the SAE J306 Standard revised in 2019.

According to the present invention, it is possible to make it excellent in extreme pressure performance based on seizure resistance and wear resistance and low temperature fluidity, and to have a high viscosity index, resulting in fuel saving. It is possible to provide a lubricating oil composition capable of improving performance and gear durability.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail with reference to its preferred embodiments. In this specification, unless otherwise specified, the notation "X to Y" for numerical values X and Y means "X or more and Y or less". In addition, when a unit is attached only to the numerical value Y in such notation, the unit is applied to the numerical value X as well.

The lubricating oil composition of the present invention contains a lubricating base oil (base oil composition) containing the base oils (A) to (B), and the base oil (A) in the lubricating base oil The content of is 45% by mass or more, the content of the base oil (B) in the lubricating base oil is 10% by mass or more, and the kinematic viscosity at 100 ° C. of the lubricating base oil is 7 00 mm ² /s or more.

<Base oil (A)>
The base oil (A) contained in the lubricating base oil (base oil composition) has a kinematic viscosity at 100° C. of 10 to 40 mm ² /s and a sulfur content of 0.3 to 2.0% by mass. is a mineral base oil. By using such a mineral base oil, it is possible to improve the durability reliability (seizure resistance and wear resistance) of the lubricating base oil.

Such base oil (A) is a mineral base oil having a kinematic viscosity at 100° C. of 10 to 40 mm ² /s. By setting the kinematic viscosity value of the base oil (A) at 100 ° C. to 10 mm ² / s or more, compared to the case of less than 10 mm ² / s, the oil film formation performance at the lubrication point is higher, and the gear resistance is increased. It is possible ^to improve the pitting performance ^and the fatigue life of the bearing, and it is also possible to improve the seizure resistance. As a result, viscosity-temperature characteristics and low-temperature viscosity characteristics are further improved, and stirring loss at low temperatures can be reduced. The kinematic viscosity of the base oil (A) at 100° C. is 15 to 35 mm ² /s from the viewpoint of obtaining higher effects in terms of improving durability reliability due to oil film forming performance and improving fuel efficiency performance due to low temperature fluidity. (more preferably 25 to 35 mm ² /s).

The base oil (A) is a mineral base oil having a sulfur content (sulfur content) of 0.3 to 2.0% by mass. By setting the sulfur content to 0.3% by mass or more, it is possible to improve the seizure resistance and wear resistance, and improve the durability and reliability, compared to the case where the sulfur content is less than 0.3% by mass. Become. On the other hand, by setting the sulfur content to 2.0% by mass or less, it is possible to improve the oxidation stability compared to the case where the sulfur content exceeds 2.0% by mass. In addition, the sulfur content of the base oil (A) is 0.4 to 1.6% by mass (further preferably 0.5 to 1.5% by mass).

In addition, such a mineral oil-based base oil (base oil (A)) preferably has a kinematic viscosity at 40° C. of 70 to 700 mm ² /s, more preferably 150 to 600 mm ² /s, and more preferably 250 to 700 mm 2 /s. 500 mm ² /s is more preferred. When the kinematic viscosity at 40° C. is equal to or higher than the lower limit, the oil film formation property at the lubricated portion is further improved and the lubricity is improved as compared with the case where the kinematic viscosity is less than the lower limit. is possible, the evaporation loss of the lubricating oil composition tends to be further reduced, and the consumption of lubricating oil tends to be further reduced. There is a tendency that higher performance (effect) can be obtained in terms of low-temperature viscosity characteristics and fuel economy performance of the lubricating oil composition compared to the case of In the present specification, "kinematic viscosity at 40°C" means kinematic viscosity at 40°C defined in JIS K 2283-2000.

In addition, the mineral base oil (base oil (A)) has a pour point of −5° C. or less (more preferably −7.5° C. or less, still more preferably −10° C. or less, particularly preferably −12.5 ° C. or less). When such a pour point is equal to or less than the upper limit, it is possible to improve the low-temperature fluidity of the entire lubricating oil composition compared to when the upper limit is exceeded, and the low-temperature fluidity of the composition is improved. There is a tendency for higher effects to be obtained in terms of In addition, the lower limit of such pour point is not particularly limited, but from the viewpoint that it is possible to make the viscosity index higher, it is preferable that the pour point is -17.5 ° C. or higher. more preferred.

Further, the mineral base oil (base oil (A)) preferably has a viscosity index of 80 or more (more preferably 85 or more, still more preferably 90 or more, and particularly preferably 95 or more). By making the viscosity index equal to or higher than the lower limit, a higher effect can be obtained in terms of fuel saving performance.

Furthermore, the mineral base oil (base oil (A)) preferably has a flash point of 250°C or higher (more preferably 260°C or higher, still more preferably 280°C or higher, and particularly preferably 300°C or higher). In addition, setting the flash point to the above lower limit or higher tends to further improve the safety during use at high temperatures, compared to the case where the flash point is lower than the above lower limit. In the present invention, the "flash point" of the base oil means the flash point measured according to JIS K 2265-4-2007 (Cleveland Open Method).

As the mineral oil-based base oil (base oil (A)), a lubricating oil fraction obtained by atmospheric distillation and vacuum distillation of crude oil, solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic Mineral base oils such as paraffinic and naphthenic base oils, normal paraffins, and isoparaffins, which have been refined by dewaxing, hydrorefining, sulfuric acid washing, clay treatment, etc. alone or in combination of two or more, can be mentioned. As such a mineral oil-based base oil (base oil (A)), solvent refining processes such as furfural solvent extraction, solvent dewaxing and catalytic dewaxing are applied to the raw material oils (1) to (8) described below. It is preferable to use a base oil produced by performing one or more of a dewaxing process such as waxing and a hydrorefining process such as hydrofinishing.
[Raw material oil (1) to (8)]
(1) Distillates from atmospheric distillation of paraffinic base and/or mixed base crudes;
(2) Vacuum Distillate (WVGO) of atmospheric distillation residue of paraffinic base and/or mixed base crude oil;
(3) Waxes obtained by the lubricating oil dewaxing process and/or Fischer-Tropsch waxes produced by the GTL process or the like;
(4) Mild hydrocracked oil (MHC) of one or more mixed oils selected from (1) to (3) above;
(5) Mixed oil of two or more oils selected from (1) to (4) above;
(6) the deasphalted oil (DAO) of (1), (2), (3), (4) or (5);
(7) the mild hydrocracked oil (MHC) of (6) above;
(8) Mixed oil of two or more oils selected from (1) to (7) above.

As the mineral base oil (base oil (A)), a Group I base oil in the classification of base oils by API (American Petroleum Institute) can be suitably used (hereinafter referred to as a base oil by API). A group of oil classifications is simply referred to as an "API group"). API Group I base oils have a sulfur content of more than 0.03% by mass (>0.03% by mass), a saturate content of less than 90% by mass (<90% by mass), and a viscosity index of 80 to 120 is a mineral base oil of less than As the mineral base oil (base oil (A)), so-called bright stock (150BS, etc.) can be suitably used. The mineral base oil used as the base oil (A) may consist of one kind of mineral oil base oil, or may consist of a mixture of two or more kinds of mineral oil base oils. There may be.

<Base oil (B)>
The base oil (B) contained in the lubricating base oil (base oil composition) has a kinematic viscosity at 100° C. of 1.5 to 3.0 mm ² /s, a viscosity index of 120 or more, and a pour point is a wax isomerized base oil having a temperature of -30°C or lower. By using such a wax isomerized base oil, it becomes possible to improve low-temperature fluidity (fuel economy) and pitting performance (fatigue life) in gear bearings.

Such base oil (B) is a wax isomerized base oil having a kinematic viscosity at 100° C. of 1.5 to 3.0 mm ² /s. By setting the kinematic viscosity of the base oil (B) to 1.5 mm ² /s or more at 100 ° C., compared to the case of less than 1.5 mm ² /s, the oil film formation performance at the lubricated location is higher, It becomes possible to improve pitting resistance performance (fatigue life). On the other hand, by setting the kinematic viscosity of the base oil (B) at 100° C. to 3.0 mm ² /s or less, the traction coefficient of the base oil becomes lower than when it exceeds 3.0 mm ² /s, It is possible to improve fuel efficiency performance. In addition, the kinematic viscosity of the base oil (B) at 100° C. is 1.9 to 2.9 mm ² /s ( More preferably 2.0 to 2.8 mm ² /s).

Base oil (B) is a wax isomerized base oil having a viscosity index of 120 or more. By setting the viscosity index of the base oil (B) to 120 or more, it is possible to further improve the lubricating effect at low temperatures compared to the case where it is less than 120, and it is possible to improve the fuel saving performance. Become. More preferably, the viscosity index of the base oil (B) is 121 or higher (more preferably 123 or higher, particularly preferably 125 or higher). By setting the viscosity index to be equal to or higher than the lower limit, there is a tendency to obtain a higher effect in terms of fuel saving performance.

Further, the base oil (B) is a wax isomerized base oil having a pour point of −30° C. or lower. When the pour point of the base oil (B) is −30° C. or less, the low-temperature performance (fluidity at low temperatures and lubricating performance at low temperatures) is superior to that when the pour point exceeds −30° C. Become. The pour point of the base oil (B) is more preferably −31° C. or lower (more preferably −33° C. or lower, particularly preferably −35° C. or lower). When such a pour point is equal to or less than the upper limit, compared with the case where the upper limit is exceeded, it is possible to improve the low temperature fluidity of the entire lubricating oil composition, and the low temperature fluidity of the composition There is a tendency to obtain a higher effect in terms of improvement. Although the lower limit of the pour point is not particularly limited, the pour point is preferably −45° C. or higher from the viewpoint of increasing the viscosity index.

In addition, such a wax isomerized base oil (base oil (B)) has a kinematic viscosity at 40° C. of 3.0 to 15.0 mm ² /s (more preferably 5.0 to 10.0 mm ² /s ) is more preferred. When the kinematic viscosity at 40°C is equal to or higher than the lower limit, the oil film formability is further improved and the lubricity is more excellent than when the kinematic viscosity is lower than the lower limit. On the other hand, when it is below the above upper limit, the low-temperature fluidity is more excellent than when the above upper limit is exceeded, and the fluid resistance becomes smaller, so the rotation resistance becomes smaller. Fuel economy tends to be further improved.

Furthermore, the wax isomerized base oil (base oil (B)) preferably has a flash point of 175°C or higher (more preferably 180°C or higher, still more preferably 185°C or higher, and particularly preferably 190°C or higher). . In addition, setting the flash point to the above lower limit or higher tends to further improve the safety during use at high temperatures, compared to the case where the flash point is lower than the above lower limit.

In addition, from the viewpoint of oxidation stability, the wax isomerized base oil (base oil (B)) has a sulfur content (sulfur content) of 30 mass ppm or less (more preferably 20 mass ppm or less, more preferably 15 mass ppm or less, particularly preferably 10 mass ppm or less). When the sulfur content is equal to or less than the above upper limit, there is a tendency to obtain a higher effect in terms of improving the oxidation stability compared to when the above upper limit is exceeded.

The % C _P of the wax isomerized base oil (base oil (B)) is preferably 85 or more (more preferably 85 to 95, still more preferably 87 to 95, particularly preferably 90 to 95). By making the %C _P of the base oil (B) equal to or higher than the above lower limit, it becomes possible to improve the viscosity-temperature characteristics and further improve the fuel economy performance. Moreover, when an additive is blended in the lubricating base oil, the effect of the additive can be further enhanced. Moreover, when the %C _P of the base oil (B) is equal to or less than the above upper limit, it becomes possible to further increase the solubility of the additive.

The % C _N of the wax isomerized base oil (base oil (B)) is preferably 2 to 15 (more preferably 3 to 12, still more preferably 4 to 10, particularly preferably 5 to 9). When the % _CN of the base oil (B) is equal to or less than the above upper limit, it becomes possible to further improve the viscosity-temperature characteristics and to further improve the fuel economy performance. Moreover, when the % _CN of the base oil (B) is equal to or higher than the above lower limit, it becomes possible to further increase the solubility of the additive.

The % C _A of the wax isomerized base oil (base oil (B)) is preferably 3 or less (more preferably 2.5 to 0, still more preferably 2 to 0, particularly preferably 1 to 0). . By making the % _CA of the base oil (B) equal to or less than the above upper limit, it becomes possible to further improve the viscosity-temperature characteristics and further improve the fuel economy performance. In addition, by setting the % _CA of the base oil (B) to the above lower limit or more, the viscosity index can be increased, which improves fuel efficiency, and the flash point can be increased, which improves safety. can be obtained.

Moreover, it is more preferable that the wax isomerized base oil (base oil (B)) satisfy the above conditions in terms of % _CP, % _CN and % _CA at the same time. That is, the wax isomerized base oil (base oil (B)) satisfies the wax isomerization conditions that %C _P is 85 or more, %C _N is 2 to 15, and %C _A is 3 or less. A modified base oil is particularly preferred.

In the present specification, % C _P , % C _N and % C _A are the total number of paraffin carbon atoms and the number of paraffin carbon atoms determined by a method (ndM ring analysis) according to ASTM D 3238-85. , the percentage of naphthenic carbon number to total carbon number, and the percentage of aromatic carbon number to total carbon number.

The wax isomerized base oil (base oil (B)) is a base oil obtained by isomerizing wax such as petroleum wax and GTL (Gas to Liquid) wax (for example, Fischer-Tropsch synthetic oil). For example, wax obtained by the lubricating oil dewaxing process and / or Fischer-Tropsch wax produced by the GTL process or the like, these waxes such as mild hydrocracked oil (MHC) and deasphalted oil (EAO) are isomerized, The product is used as it is, or a lubricating oil fraction is recovered from it, and then subjected to dewaxing treatment such as solvent dewaxing or catalytic dewaxing, and then solvent refining treatment, or after solvent refining treatment, solvent Products manufactured by performing dewaxing treatments such as dewaxing and contact dewaxing can be used as appropriate. The wax isomerization method is not particularly limited, and any known method used in the field of lubricating oils can be used as appropriate.

As the wax isomerized base oil (base oil (B)), an API Group III base oil can be suitably used. The API Group III base oil has a sulfur content of 0.03% by mass or less, a saturate content of 90% by mass or more, and a viscosity index of 120 or more. The wax isomerized base oil used as the base oil (B) may consist of one type of wax isomerized base oil, or may consist of a mixture of two or more types of wax isomerized base oils. may be

<Lubricating base oil>
The lubricating base oil contained in the lubricating oil composition of the present invention includes the base oils (A) to (B). That is, the lubricating base oil is a base oil composition (mixed base oil) containing the base oil (A) and the base oil (B).

Such a lubricating base oil has a content of the base oil (A) in the lubricating base oil of 45% by mass or more (more preferably 48% by mass or more, further preferably 50% by mass or more). there has to be Thus, by setting the content of the base oil (A) in the lubricating base oil to 45% by mass or more, the seizure resistance is particularly excellent compared to the case of less than 45% by mass. , it becomes possible to further improve the extreme pressure performance. The upper limit of the content of the base oil (A) is not particularly limited. preferably 55% by mass or less.

The lubricating base oil has a content of the base oil (B) in the lubricating base oil of 10% by mass or more (more preferably 30% by mass or more, still more preferably 40% by mass or more, particularly preferably 45% by mass % or more). By setting the content of the base oil (B) in the lubricating base oil to 10% by mass or more, gear durability (e.g., bearing fatigue life, etc.) is improved compared to the case of less than 10% by mass. becomes possible. The upper limit of the content of the base oil (B) is not particularly limited. It is preferably not more than 48% by mass, more preferably not more than 48% by mass.

The lubricating base oil preferably consists essentially of the base oils (A) to (B), but within a range that does not impair the effects of the present invention, the base oils (A) to Other base oil components than (B) may be included. In addition, even when the lubricating base oil contains other base oil components other than the base oils (A) to (B), the content of such other base oil components is the total amount of the lubricating base oil It is preferably 40% by mass or less with respect to. In addition, when using other base oils, such other base oils are not particularly limited, and known base oils can be appropriately used.

Also, the lubricating base oil should have a kinematic viscosity at 100° C. of 7.00 mm ² /s or more. By setting the kinematic viscosity at 100 ° C. of the lubricating base oil to 7.00 mm ² / s or more, compared to the case of less than 7.00 mm ² / s, wear resistance and gear durability (e.g., bearing fatigue life, etc. ) can be further improved. When the kinematic viscosity at 100° C. is 7.00 mm ² /s or more, it can be said that the lubricating base oil has a high base oil viscosity. In addition, the kinematic viscosity at 100° C. of the lubricating base oil is 7.10 to 7.50 mm ² /s (more preferably 7.50 mm 2 /s), since a higher effect can be obtained in terms of further improving wear resistance. 20 to 7.50 mm ² /s).

Further, the lubricating base oil preferably has a kinematic viscosity of 40.0 to 50.0 mm ² /s (more preferably 43.0 to 46.0 mm ² /s) at 40°C. When the kinematic viscosity at 40° C. is equal to or higher than the lower limit, the oil film formation property at the lubricated portion is further improved and the lubricity is improved as compared with the case where the kinematic viscosity is less than the lower limit. is possible, the evaporation loss of the lubricating oil composition tends to be further reduced, and the consumption of lubricating oil tends to be further reduced. There is a tendency that higher performance (effect) can be obtained in terms of low-temperature viscosity characteristics and fuel economy performance of the lubricating oil composition compared to the case of

The lubricating base oil preferably has a viscosity index of 115 or more (more preferably 118 or more, still more preferably 120 or more, and particularly preferably 122 or more). By setting the viscosity index to be equal to or higher than the lower limit, there is a tendency to obtain a higher effect in terms of fuel saving performance.

In addition, the lubricating base oil has a sulfur content of 0.20 to 1.5% by mass (more preferably 0.22 to 1.0% by mass, more preferably 0.25 to 0.80% by mass) is preferred. By making the sulfur content in the lubricating base oil equal to or higher than the lower limit, there is a tendency to obtain a higher effect in terms of improving extreme pressure performance compared to the case where it is less than the lower limit. When the content is equal to or less than the above upper limit, there is a tendency to obtain a higher effect in terms of improving the oxidation stability compared to the case where the above upper limit is exceeded. The "mass-based sulfur content in the lubricating base oil" can be determined by measurement in accordance with ASTM D4951, for example, ASTM D4951 for each base oil to be contained in the lubricating base oil may be calculated from the amount of sulfur in each base oil to be contained and the content of each base oil.

<Lubricating oil composition>
The lubricating oil composition of the present invention contains the lubricating base oil (base oil composition: mixed base oil). In the lubricating oil composition of the present invention, the content of the lubricating base oil is not particularly limited. Fluidity (high viscosity index / BF viscosity), oxidation stability (thermal stability), safety (high flash point) because higher effects can be obtained, based on the total amount of the lubricating oil composition 70 mass % or more (more preferably 75 mass % or more, still more preferably 80 mass % or more, particularly preferably 85 mass % or more).

In addition, the lubricating oil composition of the present invention can contain additives as appropriate within a range that does not impair the effects of the present invention. Such additives are not particularly limited, and depending on the application of the lubricating oil composition, known additives that are used in the field of lubricating oils (e.g., JP-A-2016-3258, International Publication 2015 /056783, JP-A-2016-160312, JP-A-2003-155492, WO-2017/073748, JP-A-2020-76004, etc.) can be used as appropriate.

Examples of such additives include, but are not particularly limited to, viscosity index improvers, pour point depressants, so-called performance additives, and the like.

Such viscosity index improvers are not particularly limited, and known viscosity index improvers can be used as appropriate. As such a viscosity index improver, a poly(meth)acrylate viscosity index improver (viscosity index improver composed of poly(meth)acrylate) is preferable from the viewpoint of the effect of increasing the viscosity index and the improvement of shear stability. available for In this specification, "(meth)acrylate" means acrylate and/or methacrylate. Such a poly(meth)acrylate viscosity index improver may be a so-called non-dispersing type or a dispersing type. The poly(meth)acrylate used for the viscosity index improver has a weight average molecular weight of 10,000 to 100,000 (more preferably 20,000 to 80,000, more preferably 30,000 to 60,000). ) is preferred. When such a poly(meth)acrylate viscosity index improver is used, the content thereof is preferably 0.1 to 15.0% by mass, more preferably 0.1 to 10.0% by mass, more preferably 0.5 to 8.0% by mass, particularly preferably 1.0 to 7.0% by mass, most preferably 2.0 to 6.0% by mass .0% by mass.

As the viscosity index improver, at least one of copolymers of ethylene and α-olefins and hydrides thereof can be suitably used from the viewpoint of thickening property and shear stability. Such copolymers and their hydrides may be of the so-called non-dispersed type or of the dispersed type. Further, the copolymer and its hydride used for the viscosity index improver preferably have a number average molecular weight of 2,000 to 10,000. The "weight average molecular weight" and "number average molecular weight" of the component used as the viscosity index improver mean values obtained by gel permeation chromatography (GPC) (molecular weight obtained by standard polystyrene conversion). do.

Moreover, the said viscosity index improver may be utilized individually by 1 type, or in combination of 2 or more types. Further, the viscosity index improver may be a poly(meth)acrylate viscosity index improver and a copolymer of ethylene and α-olefin from the viewpoint of improving viscosity index, improving low-temperature fluidity, and further improving shear stability. It is more preferable to use it in combination with a viscosity index improver. When using such a viscosity index improver, the content thereof is preferably 0.1 to 15.0% by mass, more preferably 1.0 to 15.0% by mass, based on the total amount of the lubricating oil composition. It is 12.0% by mass, more preferably 2.0 to 10.0% by mass.

The pour point depressant is not particularly limited, and known pour point depressants can be used as appropriate. Examples include poly(meth)acrylates, alkylated aromatic compounds, ethylene-propylene copolymers, fumarate-vinyl acetate copolymers, Examples include ethylene-vinyl acetate copolymers. When the base oil contains an isomerized wax base oil, among such pour point depressants, poly(meth)acrylate pour point depressants (from poly(meth)acrylate A pour point depressant) is more preferred. The pour point depressants may be used singly or in combination of two or more. When using a pour point depressant, its content is 0.01 to 1.0% by mass based on the total amount of the lubricating oil composition (more preferably is preferably 0.03 to 0.6% by mass).

Moreover, the performance additive is not particularly limited, and a known one can be used as appropriate, and a so-called additive package (a mixture of a plurality of components) may be used. As the performance additive, commercially available products ("Anglamol series" manufactured by Lubrizol, "Hitec series" manufactured by Afton Chemical, etc.) may be appropriately used.

Such a performance additive preferably has a sulfur content of 15 to 35% by mass (more preferably 20 to 30% by mass) from the viewpoint of extreme pressure properties. In addition, from the viewpoint of oxidation stability, such a performance additive preferably has a boron content of 0.05 to 1.00% by mass (more preferably 0.05 to 0.50% by mass). . Furthermore, from the viewpoint of antiwear properties, such performance additives include those having a phosphorus content of 1.0 to 3.0% by mass (more preferably 1.2 to 2.0% by mass). more preferred.

In addition, from the viewpoint of extreme pressure properties (seizure resistance performance) and anti-wear properties, such performance additives have a sulfur content ratio (mass ratio: S/P ) is 10 to 20 (more preferably 12 to 18).

In addition, when using such a performance additive, the content may be appropriately set according to the purpose of use, etc., and is not particularly limited, but is 2.0 to 14.0% by mass. is preferred. Here, as one embodiment, for example, from the viewpoint of obtaining a lubricating oil composition of API GL standard "GL-4 certification", the content of the performance additive is based on the total amount of the lubricating oil composition is more preferably 2.0 to 7.0% by mass (more preferably 3.0 to 5.0% by mass). Further, as another embodiment, for example, from the viewpoint of obtaining a lubricating oil composition of API GL standard "GL-5 certification", the content of the performance additive is based on the total amount of the lubricating oil composition More preferably 4.0 to 14.0% by mass (more preferably 5.0 to 12.0% by mass).

In addition, the viscosity index improver, the pour point depressant, the performance additive, etc. were mentioned as examples, and the additives that can be suitably used in the lubricating oil composition of the present invention were described. Additives that can be used include, but are not limited to, ashless dispersants, metallic detergents, antioxidants, antiwear agents, metal deactivators, rubber swelling agents, friction modifiers, Known additives such as foaming agents, viscosity modifiers and diluent oils can also be used as appropriate. Moreover, such additives may be used singly or in combination of two or more depending on the application of the lubricating oil composition.

In addition, in the lubricating oil composition of the present invention, the mass-based sulfur content in the lubricating oil composition may be appropriately set according to the purpose of use, etc., and is not particularly limited. 0.50 to 3.50 mass % is preferable. Here, as one embodiment, for example, from the viewpoint of obtaining a "GL-4 certified" lubricating oil composition of the API GL standard, the sulfur content on a mass basis in the lubricating oil composition is set to 0.5. It is preferably 50 to 2.50% by mass (more preferably 0.70 to 2.00% by mass, still more preferably 0.80 to 1.50% by mass). Further, as another embodiment, for example, from the viewpoint of obtaining a lubricating oil composition of API GL standard "GL-5 certification", the mass-based sulfur content in the lubricating oil composition is 1.00 It is preferable to make it to 3.50% by mass (more preferably 1.50 to 3.40% by mass, still more preferably 1.80 to 3.30% by mass). By setting the sulfur content in such a lubricating oil composition within the above range, it is possible to further improve the seizure resistance. The mass-based sulfur content in the lubricating oil composition can be measured according to ASTM D4951.

In addition, in the lubricating oil composition of the present invention, the mass-based phosphorus content in the lubricating oil composition may be appropriately set according to the purpose of use, etc., and is not particularly limited. 02% by mass or more (more preferably 0.02 to 0.25% by mass). Here, as one embodiment, for example, from the viewpoint of obtaining a lubricating oil composition of API GL standard "GL-4 certification", the content of phosphorus on the mass basis in the lubricating oil composition is set to 0.5. 02 to 0.25% by mass (more preferably 0.02 to 0.10% by mass, still more preferably 0.03 to 0.08% by mass). Further, as another embodiment, for example, from the viewpoint of obtaining a lubricating oil composition of API GL standard "GL-5 certification", the content of phosphorus based on mass in the lubricating oil composition is 0.05 It is preferably 0.25% by mass, more preferably 0.08 to 0.20% by mass. By setting the phosphorus content in such a lubricating oil composition to the above lower limit or more, there is a tendency to obtain higher effects in terms of anti-seizure and anti-wear properties compared to the case of less than the above lower limit. . On the other hand, when the phosphorus content is less than or equal to the above upper limit, there is a tendency to obtain higher effects in terms of gear/bearing fatigue life (pitting life) and oxidation stability than when the above upper limit is exceeded. It is in. The mass-based phosphorus content in the lubricating oil composition can be measured according to ASTM D4951.

The lubricating oil composition of the present invention more preferably has a kinematic viscosity at 100° C. of 11.0 to 13.5 mm ² /s (more preferably 11.0 to 12.5 mm ² /s). In addition, the kinematic viscosity at 40° C. of the lubricating oil composition of the present invention is preferably 60 to 90 mm ² /s, more preferably 65 to 80 mm ² /s, still more preferably 65 to 75 mm ² /s. be. When these kinematic viscosities are equal to or less than the above upper limit, it is possible to further improve the fuel saving performance compared to when the above upper limit is exceeded. On the other hand, when these kinematic viscosities are equal to or higher than the lower limit, the oil film retention performance is improved, and wear resistance and the like can be further improved compared to the case where the kinematic viscosity is less than the lower limit. Become.

The lubricating oil composition of the present invention preferably has a viscosity index of 155 or more (more preferably 158 or more, still more preferably 160 or more). When the viscosity index is at least the lower limit, it is possible to further improve the viscosity-temperature characteristics and wear resistance of the lubricating oil composition as compared with the case where it is less than the lower limit, and it is possible to save fuel. Performance can be further improved.

As the lubricating oil composition of the present invention, in accordance with JPI-5S-29-88, frequency: 10 kHz, vibrator amplitude: 28 μm, and irradiation time: 10 hours. When a stability test is performed and the kinematic viscosity at 100 ° C. of the lubricating oil composition before and after the ultrasonic irradiation is measured and compared, the kinematic viscosity at 100 ° C. of the lubricating oil composition by the ultrasonic irradiation The rate of decrease is preferably 10% or less (more preferably 7.0% or less, still more preferably 6.0% or less). The "decreasing rate of kinematic viscosity of the lubricating oil composition at 100°C by ultrasonic irradiation" as used herein is calculated by the following formula (I):
[Reduction rate (unit: %)]={(ν ₀ −ν ₁ )/ν ₀ }×100 (I)
[In the formula, _ν0 indicates the kinematic viscosity at 100°C of the lubricating oil composition before ultrasonic irradiation, and _ν1 indicates the kinematic viscosity at 100°C of the lubricating oil composition after ultrasonic irradiation. ]
can be obtained by calculating In addition, when the rate of decrease of the kinematic viscosity at 100 ° C. of the lubricating oil composition by such ultrasonic irradiation is equal to or less than the upper limit, the extreme pressure performance is improved compared to the case where the upper limit is exceeded. And there is a tendency to obtain a higher effect in terms of improvement in gear/bearing fatigue life (pitting life).

In addition, the lubricating oil composition of the present invention has a Brookfield viscosity (BF viscosity) at -40 ° C. of 150,000 mPa s or less (more preferably 130,000 mPa s or less, more preferably 120,000 mPa s or less, Particularly preferably, it is 100,000 mPa·s or less). By setting the BF viscosity to the above upper limit or less, it is possible to further improve the low-temperature fluidity. Such Brookfield viscosity (BF viscosity) can be measured according to ASTM D2983.

Furthermore, the lubricating oil composition of the present invention has a pour point of −37.5° C. or less (more preferably −40.0° C. or less, still more preferably −42.5° C. or less, particularly preferably −45.0° C. or less). ) is preferred. When such a pour point is equal to or lower than the upper limit, it becomes possible to exhibit better viscosity characteristics over a range from low temperature to high temperature, and it becomes possible to obtain a lubricating oil composition that is more excellent in oxidation stability. .

The lubricating oil composition of the present invention preferably has a flash point of 200° C. or higher (more preferably 205° C. or higher, still more preferably 207° C. or higher, particularly preferably 210° C. or higher). In addition, setting the flash point to the above lower limit or higher tends to further improve the safety during use at high temperatures, compared to the case where the flash point is lower than the above lower limit.

The method for producing the lubricating oil composition of the present invention is not particularly limited, and each component to be contained is such that the lubricating oil composition of the present invention can be obtained (the above conditions are satisfied). may be prepared by appropriately selecting and mixing.

The lubricating oil composition of the present invention contains a lubricating base oil having a high base oil viscosity (kinematic viscosity at 100 ° C.), and has extreme pressure performance based on anti-seizure and anti-wear properties, and low-temperature fluidity. It can be made excellent in properties and has a high viscosity index, and it is possible to improve fuel efficiency performance and gear durability (fatigue life), so it is suitable for various applications. It is applicable. Among such uses, it is particularly preferable to use it as a gear oil (gear oil composition), for example, gear oil used in manual transmissions and final reduction gears of large freight and passenger cars, gear oil for EV etc. can be suitably used. Thus, the lubricating oil composition of the present invention is preferably used as a gear oil composition. When the lubricating oil composition of the present invention is used as a gear oil composition, for example, it must satisfy the level of extreme pressure properties and gear durability (fatigue life) required for gear oils for large cargo and passenger cars. In addition, it is possible to achieve excellent fuel economy, and it is also possible to achieve both fuel economy and gear durability (fatigue life).

EXAMPLES The present invention will be described in more detail below based on examples and comparative examples, but the present invention is not limited to the following examples.

(Ingredients used in each example, etc.)
First, the base oils and additives used in each example are shown below.

[Base oil used as the base oil (A) (“mineral base oil” according to the present invention)]
<Base oil (A-1)>
Solvent Refined Mineral Oil [API Group I, 150BS (Brightstock), Kinematic Viscosity at 40° C.: 474.9 mm ² /s, Kinematic Viscosity at 100° C.: 31.92 mm ² /s, Viscosity Index: 98, Sulfur in Base Oil content (sulfur content in base oil): 0.69% by mass, pour point: -10.0°C, flash point: 322°C]
<Base oil (A-2)>
Solvent Refined Mineral Oil [API Group I, 150BS (Brightstock), Kinematic Viscosity at 40°C: 467.4 mm ² /s, Kinematic Viscosity at 100°C: 31.29 mm ² /s, Viscosity Index: 97, Sulfur in Base Oil min: 0.48% by mass, pour point: -12.5°C, flash point: 319°C]
<Base oil (A-3)>
Solvent Refined Mineral Oil [API Group I, 150BS (Brightstock), Kinematic Viscosity at 40°C: 481.8 mm ² /s, Kinematic Viscosity at 100°C: 31.76 mm ² /s, Viscosity Index: 97, Sulfur in Base Oil min: 0.51% by mass, pour point: -10.0°C, flash point: 316°C].

[Base oil used as the base oil (B) (“wax isomerized base oil” according to the present invention)]
<Base oil (B-1)>
Wax isomerized base oil [API Group III, kinematic viscosity at 40°C: 9.072 mm ² /s, kinematic viscosity at 100°C: 2.621 mm ² /s, viscosity index: 127, sulfur content in base oil: 10 mass ppm, pour point: -37.5°C, flash point: 200°C, % C _P : 91.8, % C _N : 8.2, % C _A : 0].

[Base oil (C) for comparison: base oil not corresponding to the above base oils (A) to (B)]
<Base oil (C-1)>
Solvent refined mineral oil [API Group I, 80N (neutral), kinematic viscosity at 40°C: 13.45 mm ² /s, kinematic viscosity at 100°C: 3.185 mm ² /s, viscosity index: 99, sulfur content in base oil : 0.13% by mass, pour point: -15.0°C, flash point: 198°C]
<Base oil (C-2)>
Hydrorefined mineral oil [API Group II, kinematic viscosity at 40°C: 12.43 mm ² /s, kinematic viscosity at 100°C: 3.12 mm ² /s, viscosity index: 112, sulfur content in base oil: 10 mass ppm less than (<10 mass ppm), pour point: -25.0°C, flash point: 196°C]
<Base oil (C-3)>
Solvent refined mineral oil [API Group I, 500N (neutral), kinematic viscosity at 40°C: 93.31 mm ² /s, kinematic viscosity at 100°C: 10.63 mm ² /s, viscosity index: 96, sulfur content in base oil : 0.21% by mass, pour point: -12.5°C, flash point: 266°C]
<Base oil (C-4)>
Wax isomerized base oil [API Group III, kinematic viscosity at 40°C: 15.65 mm ² /s, kinematic viscosity at 100°C: 3.883 mm ² /s, viscosity index: 142, sulfur content in base oil: 4 mass ppm, pour point: −22.5° C., flash point: 224° C., % C _P : 92.5, % C _N : 7.5, % C _A : 0].

〔Additive〕
<Viscosity index improver (D-1)>
Copolymer of ethylene and α-olefin [manufactured by Mitsui Chemicals, trade name “HC2000”, number average molecular weight: 7400]
<Viscosity index improver (D-2)>
Poly(meth)acrylate [manufactured by Evonik, trade name “Viscoplex 12-151”, weight average molecular weight: 50,000]
<Performance additive (E-1)>
Additive package [manufactured by Lubrizol, trade name “Anglamol 6043Z”, phosphorus (P) content: 1.40% by mass, sulfur (S) content: 22.9% by mass, boron (B) content : 0.24% by mass, nitrogen content: 0.9% by mass, mass ratio of phosphorus and sulfur (S/P): 16.4]
<Performance additive (E-2)>
Additive package [manufactured by Afton Chemical, trade name “HiTEC 1536”, phosphorus (P) content: 1.90% by mass, sulfur (S) content: 26% by mass, boron (B) content: 0.09% by mass, nitrogen content: 0.55% by mass, mass ratio of phosphorus and sulfur (S/P): 13.7]
<Pour point depressant (F-1)>
Poly(meth)acrylate [manufactured by Sanyo Kasei, trade name “Aclube 132”].

(Examples 1-7 and Comparative Examples 1-6)
Lubricating oil compositions of Examples 1 to 7 and Comparative Examples 1 to 6 were prepared using the respective components described above so as to have the compositions shown in Tables 1 and 2. Regarding the item of "composition" in Tables 1 and 2, "-" indicates that the component is not used. In addition, in the "composition" item in Tables 1 and 2, "inmass%" represents the content (mass%) based on the mass of the total amount of the lubricating base oil (mixed base oil), and "mass%" is lubrication It represents the content (% by mass) on a mass basis with respect to the total amount of the oil composition. Furthermore, the sulfur contents in the compositions shown in Tables 1 and 2 are values measured according to ASTM D4951. In addition, the sulfur content in the lubricating base oil shown in Tables 1 and 2 is based on the sulfur content in each base oil (sulfur content in base oil: value measured according to ASTM D4951). This is the value calculated by

[Methods for evaluating properties of lubricating oil compositions obtained in Examples]
<Measurement of Brookfield viscosity (BF viscosity)>
The BF viscosity at -40 ° C. of the lubricating oil composition obtained in each example etc. is measured according to ASTM D2983 using a Brookfield viscosity constant temperature bath / Brookfield viscometer as a measuring device, temperature: -40 °C. The results obtained are shown in Tables 1-2. When the BF viscosity is 150,000 mPa·s or less, the condition of "SAE J306 Standard Viscosity Grade 75W" is satisfied, and it can be evaluated that the fluidity at low temperatures is at a high level.

<Shear stability test>
For each of the lubricating oil compositions obtained in each example etc., in accordance with the shear stability test in accordance with JPI-5S-29-88, using a vibrator, a frequency of 10 kHz and a vibration amplitude of 28 μm. Under the conditions, ultrasonic waves are irradiated for 10 hours, the kinematic viscosity at 100 ° C. of the lubricating oil composition after ultrasonic irradiation (kinematic viscosity after testing) is obtained, and then, based on the above calculation formula (I), ultrasonic irradiation The rate of decrease in kinematic viscosity at 100° C. of the lubricating oil composition was determined. The results obtained are shown in Tables 1-2. When the reduction rate of kinematic viscosity is 10% or less, it can be said that it is more stable against shearing by ultrasonic waves, and it can be evaluated that the shearing stability is excellent. In addition, the test conditions (10 hours) for the shear stability test in accordance with the above JPI-5S-29-88, and the test conditions (CEC L-45 Method C (20 hours)) has different conditions, but both tests are considered to be alternative tests, so the kinematic viscosity after the test obtained by the shear stability test is 11.0 mm ² / s or above, it is considered to pass the test specified in the 2019 revised SAE J306 Standard (automotive gear oils) minimum kinematic viscosity (100°C).

<Abrasion resistance test>
・Measurement of welding load (high-speed four-ball test)
For each of the lubricating oil compositions obtained in Examples and the like, the welding load (WL, unit: N) at a rotation speed of 1800 rpm was measured using a high-speed four-ball tester according to ASTM D2596. The results obtained are shown in Tables 1-2.
・Measurement of wear scar diameter (wear test)
For each of the lubricating oil compositions obtained in Examples, etc., a Shell four-ball test (ASTM D4172) was performed under the conditions of load: 392 N, rotation speed: 1200 rpm, temperature: 80 ° C., test time: 1 hour. The scar diameter (mm) was measured. The results obtained are shown in Tables 1-2.
- Evaluation of wear resistance For the lubricating oil composition, when the weld load is 2500 N or more (more preferably 3000 N or more) and the wear scar diameter is less than 0.60 mm, the wear resistance is excellent. (As for the welding load, the larger the value, the higher the wear resistance. On the other hand, the smaller the value of the wear scar diameter, the higher the wear resistance. Therefore, in the present application, it is evaluated that the wear resistance is excellent when both satisfy the above conditions).

<Falex seizure resistance test>
Using a Falex tester described in ASTM D3233, the seizure load (unit: N) was measured under the test conditions of temperature: 110° C. and number of revolutions: 290 rpm. The results obtained are shown in Tables 1-2. When such a seizure load is 4000 N or more, it can be evaluated that the seizure resistance (extreme pressure property between steels) is excellent.

<Unisteel Rolling Fatigue Test>
For each of the lubricating oil compositions obtained in Examples, etc., a Unisteel rolling fatigue test was performed in accordance with the British Petroleum Institute method: IP305 standard to evaluate the rolling fatigue life of the thrust needle bearing. For such evaluation, a Unisteel rolling fatigue tester conforming to IP305 standard was used, test piece: thrust needle bearing (TP), rotation speed: 1450 rpm, surface pressure: 1 GPa, and oil temperature: 120 ° C. test conditions. , by determining the time until either the rolling elements (rollers) or bearing washers suffer fatigue damage. It was determined that fatigue damage had occurred when the measured vibration acceleration of the test portion reached 1.5 m/s ² with a vibration accelerometer provided in the Unisteel rolling fatigue tester. Then, the test was repeated 10 times, and from the time to fatigue damage measured in each test, the fatigue life was calculated by Weibull plot as 50% life (bearing fatigue life L50: time when cumulative probability reaches 50%: 50% breakage probability). The results obtained are shown in Tables 1 and 2 (However, since Comparative Examples 1 to 4 were not conducted in relation to this test, they are indicated by "-" in Table 2). When the fatigue life (L50) is 1500 minutes or more, it can be evaluated that the gear durability (bearing fatigue life) is further improved (improved) by the lubricating oil composition.

<Measurement of pour point>
The pour point of each lubricating oil composition obtained in each example was measured according to JIS K 2269-1987. The results obtained are shown in Tables 1-2. When such a pour point is -40°C or lower, it can be evaluated that the low-temperature fluidity is at a high level. When the pour point is −40° C. or less and the BF viscosity is 150,000 mPa·s or less, it can be evaluated as being superior in terms of low-temperature fluidity.

<Measurement of flash point>
The flash point of each lubricating oil composition obtained in each example was measured according to JIS K 2265-4-2007 (Cleveland Open Method). The results obtained are shown in Tables 1-2. When the flash point is 200° C. or higher, it can be evaluated that the safety during use at high temperatures is higher.

<Evaluation of fuel efficiency>
For each of the lubricating oil compositions obtained in Examples, etc., the kinematic viscosity at 25 ° C., which is the soak and test start temperature in the WLTC mode fuel consumption test, was measured in accordance with JIS K 2283-2000. Fuel efficiency was evaluated from the value of kinematic viscosity at . The results obtained are shown in Tables 1-2. When the kinematic viscosity at 25° C. is 150 mm ² /s or less, the resistance (stirring loss) due to the stirring of the lubricating oil by rotating bodies such as gears is reduced at the start of the fuel consumption test, so it is considered to be excellent in fuel efficiency. can be evaluated.

As is clear from the results shown in Tables 1 and 2, all of the lubricating oil compositions obtained in Examples 1 to 7 contained lubricating base oils containing the base oils (A) to (B). wherein the content of the base oil (A) in the lubricating base oil is 45% by mass or more, and the content of the base oil (B) in the lubricating base oil is 10 % by mass or more, and the kinematic viscosity of the lubricating base oil at 100° C. is 7.00 mm ² /s or more. In all of the lubricating oil compositions obtained in Examples 1 to 7, the results of the wear resistance test (measurement results of the weld load and the wear scar diameter) showed that the weld load was 2500 N or more, and , It was confirmed that the wear scar diameter was less than 0.60 mm, and it was confirmed that the wear resistance was excellent. and excellent extreme pressure performance based on wear resistance.

Further, from the results shown in Tables 1 and 2, all of the lubricating oil compositions obtained in Examples 1 to 7 had a BF viscosity of 150,000 mPa s or less, and "SAE J306 Standard viscosity grade 75W , and has a high level of low-temperature fluidity based on BF viscosity. In addition, all of the lubricating oil compositions obtained in Examples 1 to 7 had a pour point of -40 ° C. or less, and even when the pour point was used as a standard, the low-temperature fluidity was at a high level. I found out. Thus, all of the lubricating oil compositions obtained in Examples 1 to 7 had a pour point of −40° C. or less and a BF viscosity of 150,000 mPa s or less. It turned out to be excellent. Furthermore, all of the lubricating oil compositions obtained in Examples 1 to 7 have a viscosity index of 155 or more, and have excellent extreme pressure performance and low temperature fluidity, while having a high viscosity index. I also found out that it is.

Furthermore, from the results shown in Tables 1 and 2, all the lubricating oil compositions obtained in Examples 1 to 7 had a fatigue life (L50) of 1500 minutes or more in the Unisteel rolling fatigue test, and the gear It was found that it is possible to improve the durability (fatigue life). Further, all of the lubricating oil compositions obtained in Examples 1 to 7 had kinematic viscosities at 25° C. of 150 mm ² /g or less, demonstrating excellent fuel economy. Considering that the kinematic viscosity value at 25° C. is 150 mm ² /g or less, and that the BF viscosity is 150,000 mPa s or less and the low-temperature fluidity is high, Examples 1 to It can be seen that the lubricating oil composition obtained in No. 7 has high fuel economy.

Further, as is clear from the results shown in Tables 1 and 2, all of the lubricating oil compositions obtained in Examples 1 to 7 had a kinematic viscosity at 100°C of 11.0 mm ² /s or more and 13.5 mm ² /s or less, satisfying the conditions of "SAE J306 Standard viscosity grade 85". All of the lubricating oil compositions obtained in Examples 1 to 7 also had a kinematic viscosity of 11.0 mm ² /s or more at 100° C. after being sheared by ultrasonic irradiation. From such results, it can be evaluated that all the lubricating oil compositions obtained in Examples 1 to 7 are compatible with the 2019 revised SAE J306 Standard viscosity grade 75W-85.

On the other hand, the lubricating oil described in Comparative Example 1 using the base oil (C-1) instead of the base oil (B) without using the wax isomerized base oil (base oil (B)) The composition had a BF viscosity exceeding 150,000 mPa·s and a pour point of −27.5° C., indicating insufficient low-temperature fluidity. In addition, the lubricating oil composition described in Comparative Example 1 had a wear scar diameter of 0.60 mm or more in a wear resistance test, and was not sufficient from the viewpoint of extreme pressure properties. Furthermore, the lubricating oil composition described in Comparative Example 1 did not have sufficient fuel economy. Also, the flash point of the lubricating oil composition described in Comparative Example 1 was less than 200°C.

In addition, the lubricating oil composition described in Comparative Example 2 using the base oil (C-2) instead of the base oil (B) without using the wax isomerized base oil (base oil (B)) , the BF viscosity exceeded 150,000 mPa·s, and the low-temperature fluidity was not sufficient. In addition, the lubricating oil composition described in Comparative Example 2 had a wear scar diameter of 0.60 mm or more in a wear resistance test, and was not sufficient from the viewpoint of extreme pressure properties. Furthermore, the lubricating oil composition described in Comparative Example 2 did not have sufficient fuel economy. The flash point of the lubricating oil composition described in Comparative Example 2 was also less than 200°C.

In addition, instead of the base oil (A), a base oil (C-3) made of a mineral oil (mineral oil-based base oil that does not fall under the base oil (A)) having a sulfur content of less than 0.3% by mass is used. The lubricating oil composition described in Comparative Example 3 has a BF viscosity exceeding 150,000 mPa s and a pour point of -32.5 ° C., and sufficient low temperature fluidity. It was nothing. In addition, the lubricating oil composition described in Comparative Example 3 had a welding load of less than 2500 N in the wear resistance test, and a seizure load of less than 4000 N in the Falex seizure resistance test. The extreme pressure performance based on prevention was not sufficient. Furthermore, the lubricating oil composition described in Comparative Example 3 did not have sufficient fuel economy.

Further, instead of the base oil (B), a kinematic viscosity at 100°C of 3.0 mm ² /s or more (3.883 mm ² /s) and a pour point of -30°C or higher (-22. The lubricating oil composition described in Comparative Example 4 using the base oil (C-4) made of a wax isomerized base oil (wax isomerized base oil that does not correspond to the base oil (B)) at 5 ° C.) , the BF viscosity exceeded 150,000 mPa·s, and the low-temperature fluidity was not sufficient. In addition, the lubricating oil composition described in Comparative Example 4 was confirmed to have a weld load of less than 2500 N and a wear scar diameter of 0.60 mm or more in a wear resistance test, and sufficient wear resistance. did not become something. Furthermore, the lubricating oil composition described in Comparative Example 4 had a seizure load of less than 4000 N in the Falex seizure resistance test, and the seizure resistance was not sufficient. Thus, the lubricating oil composition described in Comparative Example 4 did not have sufficient extreme pressure performance based on seizure resistance and wear resistance.

Further, even if the base oils (A) and (B) are contained, the kinematic viscosity at 100 ° C. of the lubricating base oil is less than 7.00 ^mm / s. Lubricating oil compositions according to Comparative Examples 5 and 6 All of the products (Comparative Examples 5 and 6 were obtained by changing the content ratio of the additive component) were confirmed to have a wear scar diameter of 0.60 mm or more in the wear resistance test, and the extreme pressure property was it wasn't good enough. In addition, both of the lubricating oil compositions described in Comparative Examples 5 and 6 had a fatigue life (L50) of less than 1500 minutes in the Unisteel rolling fatigue test, indicating that gear durability (fatigue life) could be improved. could not. In addition, the lubricating oil composition described in Comparative Example 5 had a kinematic viscosity reduction rate of 12.2% after shearing, and was not sufficient in terms of shear stability as well. The kinematic viscosity at 100° C. (kinematic viscosity after the test) of the lubricating oil composition described in Comparative Example 5 after ultrasonic irradiation was less than 11.0 mm ² /s. Furthermore, the lubricating oil composition described in Comparative Example 6 had a BF viscosity exceeding 150,000 mPa·s, indicating insufficient low-temperature fluidity. From the results of the lubricating oil compositions described in Comparative Examples 5 and 6, even if the base oils (A) and (B) were contained, the kinematic viscosity at 100 ° C. of the lubricating base oil was 7.00 mm ² / It has been confirmed that the desired characteristics cannot be obtained when it is less than s.

From these results, the lubricating oil compositions obtained in Examples 1 to 7 have extreme pressure performance based on seizure resistance and wear resistance, and low temperature fluidity (especially at low temperature based on BF viscosity It was confirmed that it has excellent fluidity) and a low viscosity index, and that it is possible to improve both fuel saving performance and gear durability. Furthermore, from the results of the lubricating oil compositions obtained in Examples 1 to 7, it is assumed that the lubricating oil composition contains the lubricating base oil containing the base oils (A) to (B). , the content of the base oil (A) in the lubricating base oil is 45% by mass or more, the content of the base oil (B) in the lubricating base oil is 10% by mass or more, and By setting the kinematic viscosity of the lubricating base oil to 7.00 mm ² /s or more at 100 ° C., the lubricating oil composition can be made compatible with the 2019 revised SAE J306 Standard viscosity grade 75W-85, It is possible to have a high level of extreme pressure properties and gear durability (fatigue life) that are required when used as gear oil for large cargo and passenger cars, and excellent fuel efficiency. is clear.

As described above, according to the present invention, it is possible to achieve excellent extreme pressure performance based on seizure resistance and wear resistance, low-temperature fluidity, and a high viscosity index. It is possible to provide a lubricating oil composition capable of improving fuel efficiency and gear durability. Such a lubricating oil composition of the present invention is particularly useful as a gear oil (composition for gear oil) and the like because of its properties.

Claims (5)

The following base oils (A) to (B):
(A) a mineral base oil having a kinematic viscosity at 100° C. of 10 to 40 mm ² /s and a sulfur content of 0.3 to 2.0% by mass;
(B) a wax isomerized base oil having a kinematic viscosity at 100°C of 1.5 to 3.0 mm ² /s, a viscosity index of 120 or more and a pour point of -30°C or less;
Containing a lubricating base oil containing
The content of the base oil (A) in the lubricating base oil is 45% by mass or more,
The content of the base oil (B) in the lubricating base oil is 10% by mass or more, and
The kinematic viscosity at 100° C. of the lubricating base oil is 7.00 mm ² /s or more,
A lubricating oil composition characterized by: The base oil (B) is a wax isomerized base oil having a % C _P of 85 or more, a % C _N of 2 to 15, and a % C _A of 3 or less. The lubricating oil composition according to . In accordance with JPI-5S-29-88, a shear stability test was performed by irradiating ultrasonic waves under the conditions of frequency: 10 kHz, oscillator amplitude: 28 μm, and irradiation time: 10 hours. When the kinematic viscosity at 100 ° C. of the lubricating oil composition before and after irradiation is measured and compared, the reduction rate of the kinematic viscosity at 100 ° C. of the lubricating oil composition due to the ultrasonic irradiation is 10% or less. A lubricating oil composition according to claim 1 or 2. The lubricating oil composition according to any one of claims 1 to 3, wherein the lubricating oil composition has a Brookfield viscosity at -40°C of 150,000 mPa·s or less. The lubricating oil composition according to any one of claims 1 to 4, characterized in that said lubricating oil composition is a gear oil composition.