JP7089899B2 - Lubricating oil composition, manufacturing method of lubricating oil composition and drive system equipment - Google Patents

Description

The present invention relates to a lubricating oil composition, a method for producing a lubricating oil composition, and drive system equipment.

Lubricating oil compositions used in various applications such as shock absorbers, transmissions, drive system devices such as power steering, engines, and hydraulic operation are required to have characteristics according to each application. The characteristics of the lubricating oil composition are often greatly affected by the properties of the base oil used, the types of additives, etc., and in order to produce a lubricating oil composition capable of exhibiting the required characteristics, the base oil and the lubricating oil composition are produced. The development of additives and the development of these formulations are widely carried out.

For example, shock absorbers are used as drive train devices for automobiles such as four-wheeled vehicles and two-wheeled vehicles, and are also used in a wide range of fields such as earthquake-resistant mechanisms of houses. The lubricating oil composition used for the shock absorber is filled in the shock absorber and causes fluid resistance when the piston expands and contracts. In the case of an automobile shock absorber, vibration transmitted from the road surface to the vehicle body, and in the case of a residential shock absorber Along with the ability to dampen vibrations caused by earthquakes, the ability to lubricate sliding points inside the shock absorber is required.
In the case of a shock absorber for automobiles, the lubrication points include the rod-bush section, the rod-oil seal section, the inner tube-piston band section, etc., and by optimizing the friction characteristics at these points, the ride quality of the car In addition to controlling the friction and wear of parts, durability can be obtained. For example, Patent Document 1 discloses a shock absorber oil composition using a hydrogenated modified mineral oil or a synthetic oil as a base oil and using a specific amount of a viscosity index improver such as a high molecular weight poly (meth) acrylate. Has been done.

Japanese Unexamined Patent Publication No. 2005-314609

By the way, if glass fiber is blended in the piston band as a reinforcing material, there may be a problem that the durability of the shock absorber is lowered due to the blending of the glass fiber. The decrease in durability is caused by the increase in the amount of wear due to the wear marks generated in the sliding direction on the inner tube in contact with the piston band containing the glass fiber, and the widening of the gap between the inner tube and the piston band. It occurs when the performance deteriorates and as a result the performance of the shock absorber is impaired. The decrease in durability becomes remarkable when the wear resistance of the lubricating oil composition used for the shock absorber is insufficient. That is, in order to improve the durability of the shock absorber, it is important to improve the wear resistance of the lubricating oil composition and suppress the occurrence of wear marks on the inner tube. Further, as the performance of automobiles is improved and the operating conditions are becoming harsher year by year, the lubricating oil composition is required to have higher oxidative stability in addition to wear resistance.

The present invention has been made in view of the above circumstances, and is a lubricating oil composition having excellent wear resistance and oxidation stability, a method for producing the lubricating oil composition, and a drive system device using the lubricating oil composition. The purpose is to provide.

As a result of diligent studies in view of the above problems, the present inventors have found that the above problems can be solved by the following inventions. That is, the present invention provides a lubricating oil composition having the following constitution, a method for producing the lubricating oil composition, and a drive system device using the lubricating oil composition.

1. 1. A lubricating oil composition containing a base oil, a phosphorus compound represented by the following general formula (1), and zinc dithiophosphate.

（一般式（１）中、Ｒ^１１は炭化水素基、Ｒ^１２及びＲ^１３は各々独立に水素原子又は炭化水素基を示し、Ｒ^１２及びＲ^１３の少なくとも一方は炭化水素基である。）
２．基油と、上記一般式（１）で表されるリン化合物と、ジチオリン酸亜鉛とを配合する潤滑油組成物の製造方法。
３．基油と、上記一般式（１）で表されるリン化合物と、ジチオリン酸亜鉛とを含む潤滑油組成物を用いた駆動系機器。

(In the general formula (1), R ¹¹ represents a hydrocarbon group, R ¹² and R ¹³ each independently represent a hydrogen atom or a hydrocarbon group, and at least one of R ¹² and R ¹³ is a hydrocarbon group.)
2. 2. A method for producing a lubricating oil composition, which comprises a base oil, a phosphorus compound represented by the above general formula (1), and zinc dithiophosphate.
3. 3. A drive system device using a lubricating oil composition containing a base oil, a phosphorus compound represented by the above general formula (1), and zinc dithiophosphate.

According to the present invention, it is possible to provide a lubricating oil composition having excellent wear resistance and oxidative stability, a method for producing the lubricating oil composition, and a drive system device using the lubricating oil composition.

Hereinafter, embodiments of the present invention (hereinafter, may be simply referred to as “the present embodiment”) will be described. In addition, in this specification, the numerical values relating to "greater than or equal to", "less than or equal to" and "..." relating to the description of the numerical range are numerical values that can be arbitrarily combined.

[Lubricating oil composition]
The lubricating oil composition of the present embodiment contains a phosphorus compound represented by the following general formula (1) and zinc dithiophosphate. Hereinafter, each component that can be contained in the lubricating oil composition of the present embodiment will be specifically described.

（一般式（１）中、Ｒ^１１は炭化水素基、Ｒ^１２及びＲ^１３は各々独立に水素原子又は炭化水素基を示し、Ｒ^１２及びＲ^１３の少なくとも一方は炭化水素基である。）

(In the general formula (1), R ¹¹ represents a hydrocarbon group, R ¹² and R ¹³ each independently represent a hydrogen atom or a hydrocarbon group, and at least one of R ¹² and R ¹³ is a hydrocarbon group.)

(Phosphorus compound)
The lubricating oil composition of the present embodiment is required to contain a phosphorus compound represented by the following general formula (1) (hereinafter, may be simply referred to as "phosphorus compound"). If the lubricating oil composition of the present embodiment does not contain the phosphorus compound, the wear resistance is particularly lowered, so that excellent wear resistance and oxidative stability cannot be obtained at the same time. So far, for the purpose of improving wear resistance, a phosphate ester and a phosphite ester (both have a structure in which all the hydrocarbon groups contained in the molecule and the phosphorus atom are bonded via an oxygen atom. Abrasion resistant agents such as (esters with) have been widely used, but when these abrasion resistant agents are combined with zinc dithiophosphate, the abrasion resistance may be improved but the oxidation stability may be lowered. There was a bilateral reciprocal relationship with oxidative stability. In addition, these wear resistant agents may react with zinc dithiophosphate to cause precipitation, which may cause a problem in terms of mixing stability. The lubricating oil composition of the present embodiment is excellent as a result because by combining a specific phosphorus compound and zinc dithiophosphate, precipitation does not occur and wear resistance is improved while maintaining oxidative stability. It has made it possible to achieve both wear resistance and oxidation stability.

In the general formula (1), R ¹¹ represents a hydrocarbon group, R ¹² and R ¹³ each independently represent a hydrogen atom or a hydrocarbon group, and at least one of R ¹² and R ¹³ is a hydrocarbon group.

The hydrocarbon group of R ¹¹ is not particularly limited as long as it is a monovalent hydrocarbon group, and for example, an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group and the like are preferably mentioned from the viewpoint of improving wear resistance. Alkyl groups and alkenyl groups are more preferable, and alkyl groups are even more preferable. When these monovalent hydrocarbon groups are alkyl groups or alkenyl groups, they may be linear or branched, and the cycloalkyl groups and aryl groups are polycyclic groups such as decalyl groups and naphthyl groups. It may be a group. Further, these monovalent hydrocarbon groups have a substituent containing an oxygen atom and / or a nitrogen atom such as a hydroxyl group, a carboxy group, an amino group, an amide group, a nitro group and a cyano group, and a nitrogen atom and oxygen. It may be partially substituted with an atom, a halogen atom or the like, and when the monovalent hydrocarbon group is a cycloalkyl group or an aryl group, it further has a substituent such as an alkyl group or an alkenyl group. May be good.

From the viewpoint of improving wear resistance, the number of carbon atoms of the hydrocarbon group of R ¹¹ is preferably 1 or more, more preferably 2 or more, still more preferably 4 or more when the monovalent hydrocarbon group is an alkyl group. The upper limit is preferably 24 or less, more preferably 22 or less, still more preferably 20 or less, and when the monovalent hydrocarbon is an alkenyl group, it is preferably 2 or more, more preferably 3 or more, still more preferably 4 or more. The upper limit is preferably 24 or less, more preferably 22 or less, and further preferably 20 or less. When the monovalent hydrocarbon is a cycloalkyl group, the carbon number is preferably 5 or more and 20 or less, and when the monovalent hydrocarbon is an aryl group, the carbon number is preferably 6 or more and 20 or less.

At least one of R ¹² and R ¹³ is required to be a hydrocarbon group. When both R ¹² and R ¹³ are hydrogen atoms, it becomes difficult to obtain excellent wear resistance. From the viewpoint of obtaining better wear resistance, it is preferable that both R ¹² and R ¹³ are hydrocarbon groups.
The hydrocarbon groups of R ¹² and R ¹³ are not particularly limited as long as they are monovalent hydrocarbon groups, and the above-exemplified hydrocarbon groups of R ¹¹ are preferably mentioned. When both R ¹² and R ¹³ are hydrocarbon groups, R ¹² and R ¹³ may be the same or different, but are preferably the same from the viewpoint of improving wear resistance.

Further, from the viewpoint of improving wear resistance, the number of carbon atoms of the hydrocarbon groups of R ¹² and R ¹³ is preferably 1 or more, more preferably 2 or more when the monovalent hydrocarbon group is an alkyl group. The upper limit is preferably 12 or less, more preferably 8 or less, still more preferably 6 or less. When the monovalent hydrocarbon is an alkenyl group, it is preferably 2 or more, and the upper limit is preferably 12 or less, more preferably 8 or less, still more preferably 4 or less. When the monovalent hydrocarbon is a cycloalkyl group, the carbon number is preferably 5 or more and 20 or less, and when the monovalent hydrocarbon is an aryl group, the carbon number is preferably 6 or more and 20 or less.

The content of the phosphorus compound based on the total amount of the composition is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, still more preferably, from the viewpoint of more efficiently improving wear resistance and oxidation stability. Is 0.3% by mass or more, and the upper limit is preferably 3% by mass or less, more preferably 2% by mass or less, and further preferably 1% by mass or less.

(Zinc dithiophosphate)
The lubricating oil composition of the present embodiment is required to contain zinc dithiophosphate. If the lubricating oil composition of the present embodiment does not contain zinc dithiophosphate, the oxidative stability is particularly lowered, so that excellent wear resistance and oxidative stability cannot be obtained at the same time. As the zinc dithiophosphate used in the lubricating oil composition of the present embodiment, those represented by the following general formula (2) are preferably mentioned.

In the general formula (2), R ²¹ to R ²⁴ each independently represent a hydrocarbon group. The hydrocarbon group is not particularly limited as long as it is a monovalent hydrocarbon group. For example, an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group and the like are preferably mentioned from the viewpoint of improving oxidative stability. A group and an aryl group are more preferable, and an alkyl group is further preferable. That is, as the zinc dithiophosphate used in the present embodiment, zinc dialkyldithiophosphate and zinc diaryldithiophosphate are more preferable, and zinc dialkyldithiophosphate is even more preferable.

The alkyl group and alkenyl group of R ²¹ to R ²⁴ may be linear or branched, but from the viewpoint of obtaining better oxidative stability, primary and secondary ones are preferable. Among them, a primary alkyl group and a secondary alkyl group are preferable, and a primary alkyl group is more preferable. Zinc dialkyldithiophosphate is preferable, and primary zinc dialkyldithiophosphate is more preferable.
The cycloalkyl group and aryl group of R ²¹ to R ²⁴ may be a polycyclic group such as a decalyl group or a naphthyl group.
Further, these monovalent hydrocarbon groups may have a substituent exemplified as a substituent that can be possessed by R ¹¹ to R ¹³ , and are substituted with a nitrogen atom, an oxygen atom, a halogen atom or the like. It may be a thing.

From the viewpoint of improving oxidative stability, the number of carbon atoms of the hydrocarbon groups of R ²¹ to R ²⁴ is preferably 1 or more, more preferably 2 or more, still more preferably 2 or more when the monovalent hydrocarbon group is an alkyl group. It is 3 or more, and the upper limit is preferably 24 or less, more preferably 18 or less, still more preferably 12 or less, and when the monovalent hydrocarbon is an alkenyl group, it is preferably 2 or more, more preferably 3 or more. The upper limit is preferably 24 or less, more preferably 18 or less, still more preferably 12 or less. When the monovalent hydrocarbon is a cycloalkyl group, the number of carbon atoms is preferably 5 or more, and the upper limit is preferably 20 or less. When the monovalent hydrocarbon is an aryl group, the number of carbon atoms is preferably 6 or more. The upper limit is preferably 20 or less.

The content of zinc dithiophosphate based on the total amount of the composition is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, still more preferably 0. 3% by mass or more. Further, from the viewpoint of further improving the wear resistance, the upper limit is preferably 3% by mass or less, more preferably 2% by mass or less, still more preferably 1% by mass or less.

(Base oil)
The base oil contained in the lubricating oil composition of the present embodiment may be either mineral oil or synthetic oil.
As the mineral oil, the atmospheric pressure residual oil obtained by atmospheric distillation of paraffin-based, naphthen-based, and intermediate-based crude oil; the distillate obtained by vacuum distillation of the atmospheric residual oil; the distillate. Mineral oil refined by performing one or more treatments such as solvent desorption, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, etc., for example, light neutral oil, medium neutral. Examples thereof include oil, heavy neutral oil, bright stock, and mineral oil obtained by isomerizing a wax (GTL wax) produced by the Fisher-Tropsch method or the like.
The mineral oil may be classified into any of groups 1, 2, and 3 in the base oil category of API (American Petroleum Institute), but sludge formation can be further suppressed, and viscosity characteristics and oxidation can be achieved. From the viewpoint of obtaining stability against deterioration and the like, those classified into groups 2 and 3 are preferable.

Examples of the synthetic oil include poly-α-olefins such as polybutene, ethylene-α-olefin copolymer, α-olefin homopolymer or copolymer; various types such as polyol ester, dibasic acid ester and phosphoric acid ester. Examples thereof include ester oils; various ethers such as polyphenyl ethers; polyglycols; alkylbenzenes; alkylnaphthalene and the like.

In the present embodiment, the base oil may be at least one kind of mineral oil, at least one kind of synthetic oil, or a mixed oil in which at least one kind of mineral oil and at least one kind of synthetic oil are mixed. In the present embodiment, mineral oil is preferable from the viewpoints of low cost, better viscosity characteristics, resistance to evaporation, and fuel saving performance due to low viscosity.

The viscosity of the base oil is not particularly limited, but from the viewpoint of preventing seizure at high temperatures, the kinematic viscosity at 40 ° C. is preferably 3 mm ² / s or more, more preferably 5 mm ² / s or more, and 7 mm ² / s or more. Is more preferable. Further, from the viewpoint of ensuring low temperature fluidity, 35 mm ² / s or less is preferable, 25 mm ² / s or less is more preferable, and 20 mm ² / s or less is further preferable. From the same viewpoint, the kinematic viscosity of the base oil at 100 ° C. is preferably 1 mm ² / s or more, more preferably 1.5 mm ² / s or more, still more preferably 2 mm ² / s or more. The upper limit is preferably 15 mm ² / s or less, more preferably 10 mm ² / s or less, and even more preferably 5 mm ² / s or less.
The viscosity index of the base oil is preferably 85 or more, more preferably 90 or more, and even more preferably 100 or more. In the present specification, the kinematic viscosity and the viscosity index are values measured using a glass capillary viscometer according to JIS K 2283: 2000. When the kinematic viscosity and the viscosity index of the base oil are within the above ranges, the lubricating oil composition has a more appropriate viscosity, and the wear resistance and the oxidation stability are improved.

The content of the base oil based on the total amount of the composition is preferably 60% by mass or more, more preferably 60% by mass or more, from the viewpoint of having a more appropriate viscosity as a lubricating oil composition and improving wear resistance and oxidation stability. It is 70% by mass or more, more preferably 85% by mass or more. The upper limit is preferably 99.9% by mass or less, more preferably 99% by mass or less, and further preferably 98% by mass or less.

(Other additives)
The lubricating oil composition of the present embodiment contains the above-mentioned base oil, a phosphorus compound, and zinc dithiophosphate, and may be composed of a base oil, a phosphorus compound, and zinc dithiophosphate, or a group. In addition to oils, phosphorus compounds, and zinc dithiophosphate, for example, other additions such as viscosity index improvers, dispersants, antioxidants, extreme pressure agents, metal inactivating agents, defoamers, friction reducing agents, and oily agents. It may contain an agent. These other additives can be used alone or in combination of two or more.
The total content of these other additives may be appropriately determined as desired and is not particularly limited, but considering the effect of adding the other additives, it is preferably 0.10 mass based on the total amount of the composition. % Or more, more preferably 0.20% by mass or more, still more preferably 0.30% by mass or more, and the upper limit is preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less. be.

As the viscosity index improver, for example, the mass average molecular weight (Mw) is preferably 500 to 1,000,000, more preferably 5,000 to 800,000, still more preferably 10,000 to 700,000. Polymethacrylates such as type polymethacrylates and dispersed polymethacrylates; the mass average molecular weight (Mw) is preferably 800 to 300,000, more preferably 10,000 to 200,000, still more preferably 20,000 to 150,000. Olefin-based copolymers (eg, ethylene-propylene copolymers, etc.), dispersed olefin-based copolymers, styrene-based copolymers (eg, styrene-diene copolymers, styrene-isoprene copolymers, etc.), etc. Polymers; and the like.

Examples of the dispersant include boron-free succinic acid imides, boron-containing succinic acid imides, benzylamines, boron-containing benzylamines, succinic acid esters, fatty acids, and monovalent or divalent succinic acid. Examples thereof include ashless dispersants such as carboxylic acid amides.

Examples of the antioxidant include amine-based antioxidants such as diphenylamine-based antioxidants and naphthylamine-based antioxidants; monophenol-based antioxidants, diphenol-based antioxidants, hindered phenol-based antioxidants, and the like. Examples include a phenol-based antioxidant; a molybdenum-based antioxidant such as a molybdenum amine complex formed by reacting molybdenum trioxide and / or molybdic acid with an amine compound; and the like.

Extreme pressure agents include sulfur-based extreme pressure agents such as sulfide oils and fats, sulfide fatty acids, sulfide esters, sulfide olefins, dihydrocarbylpolysulfide, thiadiazol compounds, alkylthiocarbamoyl compounds, and thiocarbamate compounds; zinc dialkylthiocarbamate (Zn-DTC). , Sulfur-nitrogen extreme pressure agent such as dialkylthiocarbamic acid molybdenum (Mo-DTC); sulfur-phosphorus extreme pressure agent such as dialkyldithiophosphate molybdenum (Mo-DTP); and the like.

Examples of the metal inactivating agent include benzotriazole-based, tolyltriazole-based, thiadiazol-based, and imidazole-based compounds, and examples of the defoaming agent include silicone-based defoaming agents such as silicone oil and fluorosilicone oil. Examples thereof include ether-based defoaming agents such as fluoroalkyl ethers, and examples of the friction reducing agent include aliphatic alcohols, fatty acids, fatty acid esters, aliphatic amines, aliphatic amine salts, and aliphatic amides, and oil-based agents. Examples thereof include glycerol esters such as glycerol monooleate and glycerol dioleate.

(Various physical characteristics of lubricating oil composition)
The kinematic viscosity of the lubricating oil composition of the present embodiment at 40 ° C. is preferably 5 mm ² / s or more and 35 mm ² / s or less, more preferably 7 mm, from the viewpoint of preventing seizure at high temperature and ensuring low temperature fluidity. It is ² / s or more and 25 mm ² / s or less, more preferably 9 mm ² / s or more and 15 mm ² / s or less. From the same viewpoint as this, the kinematic viscosity of the lubricating oil composition of the present embodiment at 100 ° C. is preferably 0.5 mm ² / s or more and 15 mm ² / s or less, and more preferably 1 mm ² / s or more and 10 mm ² / s. Below, it is more preferably 1.5 mm ² / s or more and 5 mm ² / s or less. The viscosity index of the lubricating oil composition of the present embodiment is preferably 85 or more, more preferably 90 or more, and further preferably 100 or more.

Regarding the phosphorus atom content of the lubricating oil composition of the present embodiment, the total phosphorus atom content contained in the composition is P ₀ (mass%), and the phosphorus atom content derived from the phosphorus compound is P ₁ (mass%). ), The ratio P ₁ / P ₀ of the phosphorus atom content derived from the phosphorus compound to the total phosphorus atom content is preferably 50 from the viewpoint of more efficiently improving wear resistance and oxidation stability. % Or less, more preferably 45% or less, still more preferably 40% or less, particularly preferably 35% or less, and the lower limit is preferably as small as possible from the viewpoint of cost, but it is usually used from the viewpoint of the effect of using the phosphorus compound. It is 1% or more, preferably 5% or more.

(Use of lubricating oil composition)
Since the lubricating oil composition of the present embodiment is excellent in wear resistance and oxidation stability, for example, it is used for drive system equipment such as shock absorbers, transmissions and power steering, for engines, for hydraulic operation, and for turbines. , For compressors, machine tools, cutting, gears, fluid bearings, rolling bearings, etc. Among them, considering the characteristics of excellent wear resistance and oxidative stability, it is preferably used for drive system equipment, and shock absorbers, especially automobile shock absorbers such as four-wheeled vehicles and two-wheeled vehicles, particularly four-wheeled vehicle shock absorbers. It is more preferable to be used in.
Further, from the viewpoint of effectively utilizing particularly excellent wear resistance, the above-mentioned equipment can be suitably used for equipment having a member containing glass fiber as a reinforcing material, for example, glass fiber is blended as a reinforcing material. It is suitably used for shock absorbers that have a piston band as a member and require lubrication between the inner tube and the piston band, especially for automobile shock absorbers such as four-wheeled vehicles and two-wheeled vehicles, and especially for four-wheeled vehicle shock absorbers. Will be.

[Manufacturing method of lubricating oil composition]
The method for producing a lubricating oil composition of the present embodiment is characterized by blending a base oil, a phosphorus compound represented by the following general formula (1), and zinc dithiophosphate.

（一般式（１）中、Ｒ^１１は炭化水素基、Ｒ^１２及びＲ^１３は各々独立に水素原子又は炭化水素基を示し、Ｒ^１２及びＲ^１３の少なくとも一方は炭化水素基である。）

(In the general formula (1), R ¹¹ represents a hydrocarbon group, R ¹² and R ¹³ each independently represent a hydrogen atom or a hydrocarbon group, and at least one of R ¹² and R ¹³ is a hydrocarbon group.)

In the method for producing the lubricating oil composition of the present embodiment, the base oil, the phosphorus compound, and zinc dithiophosphate are the same as those described as those contained in the lubricating oil composition of the present embodiment, and their contents are the same. , The content is the same as that described as the content in the lubricating oil composition of the present embodiment. Further, in the method for producing the lubricating oil composition of the present embodiment, components other than the base oil, the phosphorus compound and zinc dithiophosphate, for example, other additives described as components that can be contained in the lubricating oil composition of the present embodiment are blended. You may.

When producing a lubricating oil composition, the phosphorus compound and zinc dithiophosphate are added to the base oil from the viewpoint of obtaining a lubricating oil composition having more stable properties in the blending of the base oil, the phosphorus compound and zinc dithiophosphate. Is preferable. From the same viewpoint as this, when other additives are added, it is preferable to sequentially add various additives used as other additives to a mixture of a base oil, a phosphorus compound and zinc dithiophosphate.

[Drive system equipment]
The drive system device of the present embodiment is characterized by using a lubricating oil composition containing a base oil, a phosphorus compound represented by the following general formula (1), and zinc dithiophosphate.

（一般式（１）中、Ｒ^１１は炭化水素基、Ｒ^１２及びＲ^１３は各々独立に水素原子又は炭化水素基を示し、Ｒ^１２及びＲ^１３の少なくとも一方は炭化水素基である。）

(In the general formula (1), R ¹¹ represents a hydrocarbon group, R ¹² and R ¹³ each independently represent a hydrogen atom or a hydrocarbon group, and at least one of R ¹² and R ¹³ is a hydrocarbon group.)

The base oil, phosphorus compound, and zinc dithiophosphate contained in the lubricating oil composition used for the drive system equipment of the present embodiment are the same as those described as those contained in the lubricating oil composition of the present embodiment, and these are the same. The content of the above is the same as that described as the content in the lubricating oil composition of the present embodiment. Further, in the lubricating oil composition used for the driving system equipment of the present embodiment, components other than the base oil, the phosphorus compound and zinc dithiophosphate, for example, other components described as components that can be contained in the lubricating oil composition of the present embodiment are added. The agent may be blended.

Drivetrain equipment mainly includes shock absorbers, transmissions, power steering and the like. From the viewpoint of effectively utilizing the particularly excellent wear resistance of the lubricating oil composition used in the drive system device of the present embodiment, a device having a member containing glass fiber as a reinforcing material is preferable. For example, a shock absorber having a piston band containing glass fiber as a reinforcing material and requiring lubrication between the inner tube and the piston band, especially a shock absorber for automobiles such as four-wheeled vehicles and two-wheeled vehicles, particularly four. A shock absorber for a wheel wheel is preferable.

Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

The properties and performance of the lubricating oil composition were measured and evaluated by the following methods.
(1) Dynamic viscosity The kinematic viscosity at 40 ° C and 100 ° C was measured according to JIS K 2283: 2000.
(2) Viscosity index (VI)
Measured according to JIS K 2283: 2000.
(3) Appearance Evaluation Visually observe the appearance of the lubricating oil compositions of Examples and Comparative Examples in which each component shown in Table 1 was mixed at 60 ° C. and then stored at room temperature (20 ° C.) for 1 day. It was confirmed and the presence or absence of precipitation was evaluated. Those in which precipitation occurs have low mixing stability and cannot withstand use as a lubricating oil composition.
(4) Evaluation of Wear Resistance For the lubricating oil compositions of Examples and Comparative Examples obtained by mixing the components shown in Table 1, a ball-on-disk type reciprocating friction tester (Bowden-Leben). Using the formula), a friction test was performed with a load of 29.4 N, a temperature of 100 ° C., a slip speed of 50 mm / s, a stroke of 10 mm, and a time of 30 minutes, and the wear mark width on the disk was measured. The ball is a glass ball (diameter 12 mm), and the disc is made of the material SPCC-SB. It can be said that the smaller the wear mark width, the better the wear resistance.
(5) Evaluation of Oxidation Stability The lubricating oil compositions of Examples and Comparative Examples obtained by mixing the components shown in Table 1 were subjected to an ISOT test based on JIS K2514-1: 2013. A copper plate and an iron plate were added to the lubricating oil composition as catalysts, the sample was deteriorated at a test temperature of 120 ° C., a test time of 24 hours, and a stirring speed of 1300 rpm, and then the amount of copper elution was measured. It can be said that the smaller the elution amount of copper, the better the oxidative stability.

(Preparation of Lubricating Oil Compositions of Examples 1 and 2 and Comparative Examples 1 to 5)
A lubricating oil composition was prepared by blending according to the blending formula shown in Table 1 below. Table 1 shows the evaluation results of each property and performance measured by the above method for each of the obtained lubricating oil compositions.

The details of each component shown in Table 1 used in this example are as follows.
-Base oil 1: 60N hydrorefined oil (40 ° C. kinematic viscosity: 7.83 mm ² / s, 100 ° C. kinematic viscosity: 2.22 mm ² / s, viscosity index: 83)
-Base oil 2: 70N hydrorefined oil (40 ° C. kinematic viscosity: 9.92 mm ² / s, 100 ° C. kinematic viscosity: 2.71 mm ² / s, viscosity index: 114)
-Phosphorus compound 1: Diethylstearylphosphonate (in the general formula ^{( 1} ), R11 is a stearyl group and ^R12 and R13 are ethyl groups).
-Phosphorus compound 2: Monooleyl acid phosphate-Phosphorus compound 3: Tricredyl phosphite-Zinc dithiophosphate 1: Primary dialkyl Zinc dithiophosphate (primary alkyl groups having 3, 4 and 6 carbon atoms in the molecule) A mixture of those having at least one alkyl group)
Zinc dithiophosphate 2: Primary dialkyl Zinc dithiophosphate (a mixture of molecules having at least one alkyl group of 8 and 10 carbon atoms)
-Fatty acid amide: A reaction product of isostearic acid and tetraethylenepentamine.
-Viscosity index improver 1: Polymethacrylate (Mw: 140,000)
-Viscosity index improver 2: Polymethacrylate (Mw: 550,000)
-Other additives: Phenolic antioxidants, metal deactivating agents (thiadiazole, etc.), silicone defoamers

From the results shown in Table 1, the lubricating oil compositions of the present embodiment are excellent in mixing stability without causing precipitation, and have an excellent wear mark width of 0.55 mm or less, preferably 0.53 mm or less. It was confirmed that the copper has excellent wear resistance and the elution amount of copper is 10% by mass or less, preferably 5% by mass or less, and has excellent oxidative stability.
On the other hand, the lubricating oil compositions of Comparative Examples 1 and 2 containing no phosphorus compound represented by the general formula (1) have wear scar widths of 0.64 mm and 0.61 mm and have excellent wear resistance. It couldn't be said. The lubricating oil composition of Comparative Example 3 contained oleyl acid phosphate and tricresyl phosphite in place of the phosphorus compound represented by the general formula (1) and did not contain zinc dithiophosphate, and was worn. The trace width was 0.52 mm, which was excellent in wear resistance, but the elution amount of copper was 105 mass ppm, which was extremely inferior in oxidative stability. The lubricating oil composition of Comparative Example 4 contains oleyl acid phosphate instead of the phosphorus compound represented by the general formula (1), but precipitation occurs due to the reaction between oleyl acid phosphate and zinc dithiophosphate. Therefore, it could not be used as a lubricating oil composition (therefore, wear resistance and oxidation stability were not evaluated). Further, the lubricating oil composition of Comparative Example 5 did not contain zinc dithiophosphate, and the elution amount of copper was 2% by mass or less, which was excellent in oxidative stability, but the wear scar width. Was 0.57 mm, which was not excellent in wear resistance.

Claims (14)

A lubricating oil composition for a shock absorber containing a base oil, a phosphorus compound represented by the following general formula (1), and zinc dithiophosphate.

(In the general formula (1), R ¹¹ represents a hydrocarbon group, R ¹² and R ¹³ each independently represent a hydrogen atom or a hydrocarbon group, and at least one of R ¹² and R ¹³ is a hydrocarbon group.) In the general formula (1), R ¹¹ is an alkyl group having 1 or more and 24 or less carbon atoms or an alkenyl group having 2 or more and 24 or less carbon atoms, and R ¹² and R ¹³ are independently alkyl groups having 1 or more and 12 or less carbon atoms. The lubricating oil composition according to claim 1, which is a group or an alkenyl group having 2 or more and 12 or less carbon atoms. The lubricating oil composition according to claim 1 or 2, wherein the content of the phosphorus compound based on the total amount of the composition is 0.01% by mass or more and 3% by mass or less. The lubricating oil composition according to any one of claims 1 to 3, wherein the zinc dithiophosphate is zinc dialkyl dithiophosphate. The lubricating oil composition according to claim 4, wherein the zinc dialkyldithiophosphate is a primary zinc dialkyldithiophosphate. The lubricating oil composition according to claim 4 or 5, wherein the zinc primary dialkyl dithiophosphate has a primary alkyl group having 1 or more and 24 or less carbon atoms. The lubricating oil composition according to any one of claims 1 to 6, wherein the content of the zinc dithiophosphate based on the total amount of the composition is 0.01% by mass or more and 3% by mass or less. Any of claims 1 to 7, wherein the ratio P ₁ / P ₀ of the phosphorus atom content P ₁ (mass%) derived from the phosphorus compound to the total phosphorus atom content P ₀ (mass%) is 50% or less. The lubricating oil composition according to item 1. The lubricating oil composition according to any one of claims 1 to 8, wherein the 40 ° C. kinematic viscosity is 5 mm ² / s or more and 35 mm ² / s or less. The lubricating oil composition according to any one of claims 1 to 9, which has a viscosity index of 85 or more. The lubricating oil composition according to any one of claims 1 to 10, further comprising a glycerol ester as an oily agent. A method for producing a lubricating oil composition for a shock absorber, which comprises a base oil, a phosphorus compound represented by the following general formula (1), and zinc dithiophosphate.

(In the general formula (1), R ¹¹ represents a hydrocarbon group, R ¹² and R ¹³ each independently represent a hydrogen atom or a hydrocarbon group, and at least one of R ¹² and R ¹³ is a hydrocarbon group.) A shock absorber using a lubricating oil composition for a shock absorber, which comprises a base oil, a phosphorus compound represented by the following general formula (1), and zinc dithiophosphate .

(In the general formula (1), R ¹¹ represents a hydrocarbon group, R ¹² and R ¹³ each independently represent a hydrogen atom or a hydrocarbon group, and at least one of R ¹² and R ¹³ is a hydrocarbon group.) 13. The shock absorber according to claim 13, which is for automobiles.