JP6718273B2 - Lubricating oil composition for hydraulic actuator equipped with electronic control device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a lubricating oil composition for a hydraulic actuator having conductivity so as not to cause malfunction or failure in an electronic control device such as an electronic control valve system.

Petroleum, such as general lubricating oil, is a liquid with good insulating properties, whose main component is hydrocarbon. It has been known for quite some time that static electricity is generated when such a liquid is sent through a pipe or the like (referred to as flow electrification) (Non-Patent Document 1).
The electric charges generated at this time are carried to the storage tank together with the liquid, and are charged and discharged inside or around the tank container to generate sparks, which may ignite the liquid. For such a phenomenon, in order to suppress the accumulation of static electricity and prevent the generation of sparks, for example, STADIS-containing dinonylnaphthylsulfonic acid as an active ingredient which enhances electric conductivity (conductivity, electric conductivity). It is known to add 450 (manufactured by DuPont) or the like.

Further, in recent years, due to the high performance of hydraulic devices, there is an increasing risk that static electricity will be generated due to higher speed oil supply. A spark generated by an electric phenomenon generated at an interface between a solid and oil such as a storage tank becomes noise, which causes a problem that a control device including electronic parts malfunctions or fails.

In particular, hydraulic fluid is a power transmission fluid used for operations such as power transmission, force control, and buffering in hydraulic systems such as hydraulic equipment and devices, and also fulfills the function of lubricating sliding parts.
Recent hydraulic equipment is becoming smaller and higher in output, and accordingly, the working pressure has been increased from 14 to 20 MPa in the past to 30 MPa or more, and the oil feeding speed is high. Therefore, there is a higher possibility that flow electrification will occur.
Since these hydraulic systems are usually equipped with electronically controlled valve systems, it is desirable to take measures to prevent spark noise and to use oil with a high flash point from the safety aspect of storage. Further, when it is used for lubrication of a wet brake, it is required to have an appropriate friction coefficient so as to prevent braking failure.

In order to improve the conductivity of the lubricating oil composition, those having a strong polar group and a lipophilic group of a suitable size in the molecule such as an organometallic compound, a succinic acid derivative or an amine derivative, and an aromatic azo It is known that a combination of compounds is contained in a base oil. However, since the aromatic azo compound is an essential component, the lubricating oil has a red color, which makes it difficult to visually determine the deterioration of the lubricating oil on site, and considers the conductivity and braking characteristics. not. (Patent Document 1)

JP 2001-234187 A

Aichi Institute of Technology Research Report B Specialized Proceedings 14, 1-6, "Liquid Capillary Flow Charging" March 31, 1979

INDUSTRIAL APPLICABILITY The present invention provides conductivity in order to prevent noise that adversely affects electronic control equipment such as electronically controlling a valve system, has excellent braking characteristics of an electronically controlled wet brake, and is safe. It is intended to provide a lubricating oil composition having excellent properties for a hydraulic actuator.

The present invention uses a hydrocarbon base oil as a base oil, and the base oil has an overbased calcium salicylate as a calcium content of 30 to 100 ppm with respect to the total amount of the composition, and a weight average molecular weight of 5,000 to 20. It is a composition containing 0.07 to 2.0 mass% of the total amount of the composition as a net amount of non-dispersed polymethacrylate. The electrical conductivity of this composition at 25° C. is 200 pS/m or more (S-Siemens notation), the flash point is 240° C. or more, the pour point is −40° C. or less, and the micro clutch test method at 140° C. Has a friction coefficient of 0.08 or more, and is a lubricating oil composition for use in a hydraulically operated machine provided with an electronic control device that does not contain an ashless friction modifier and an azo compound .

The base oil may contain GTL (gas liquid) base oil, preferably 40% by mass or more.
The lubricating oil composition further contains zinc dialkyldithiophosphate in an amount of 100 to 1000 ppm as a phosphorus amount based on the total amount of the composition, and the kinematic viscosity of the composition at 40° C. is 10 to 100 mm ² /s. Good to do.

The lubricating oil composition of the present invention is capable of increasing conductivity, has a low pour point, can prevent ignition due to static charge due to low flow charge, and has a high flash point. It can be used safely and safely, and it prevents the generation of noise that adversely affects electronic control equipment such as electronically controlling the valve system, and also has excellent hydraulic characteristics for the braking characteristics of electronically controlled wet brakes. It may be a lubricating oil composition for motives.

In the present invention, a hydrocarbon base oil is used as the base oil.
The hydrocarbon base oil is a base oil belonging to Group 1, Group 2, Group 3, and Group 4 in the API (American Petroleum Institute) base oil category, and these may be used alone or as appropriate. It is a mixture.

The Group 1 base oil is obtained, for example, by applying a suitable combination of refining means such as solvent refining, hydrorefining and dewaxing to a lubricating oil fraction obtained by distilling crude oil under atmospheric pressure. The paraffinic mineral oils mentioned may be mentioned.
The Group 1 base oil used here has a kinematic viscosity at 100° C. (measured by ASTM D445, JIS K2283; the same applies hereinafter) of ² to 15 mm ² /s, preferably 4 to 15 mm ² /s, and more preferably is of 6~11mm ² / s, viscosity index (as measured by ASTM D2270, JIS K2283. hereinafter the same.) 90 to 120, preferably 95-120, more preferably 95-110. The sulfur content is 0.03 to 0.7% by mass, preferably 0.3 to 0.7% by mass, and more preferably 0.4 to 0.7% by mass. %CA according to ASTM D3238 is 5 or less, preferably 4 or less, more preferably 3.4 or less, and %CP is 60 or more, preferably 63 or more, more preferably 66 or more.

The Group 2 base oil is, for example, a paraffinic base oil obtained by applying a suitable combination of refining means such as hydrocracking and dewaxing to a lubricating oil fraction obtained by distilling crude oil under atmospheric pressure. Mineral oil may be mentioned. The Group 2 base oil refined by the hydrorefining method such as the Gulf Company method has a total sulfur content of less than 10 ppm and an aroma content of 5% or less, and can be suitably used.
The viscosity of the base oil is not particularly limited, but the viscosity index is preferably 100 to 120. The kinematic viscosity at 100° C. is ² to 15 mm ² /s, preferably 4 to 15 mm ² /s, more preferably 6 to 11 mm ² /s. The total sulfur content is less than 0.03% by mass (300 ppm), preferably less than 0.02% by mass (200 ppm), and more preferably less than 0.001% by mass (10 ppm). The total nitrogen content should also be less than 10 ppm, preferably less than 1 ppm. Further, the aniline point (measured by ASTM D611, JIS K2256) of 80 to 150° C., preferably 100 to 135° C., may be used.

In addition, for lubricating oil fractions obtained by distilling crude oil under atmospheric pressure, ISODEWAX is used for converting and dewaxing paraffinic mineral oil produced by advanced hydrorefining and wax produced in the dewaxing process into isoparaffin. A base oil refined by the process and a base oil refined by the Mobile WAX isomerization process can also be preferably used.
These base oils correspond to API Group 2 and Group 3 base oils. The viscosity is not particularly limited, but the viscosity index is 100 to 160, preferably 100 to 145. The kinematic viscosity at 100° C. is preferably ² to 15 mm ² /s, more preferably 4 to 15 mm ² /s, and further preferably 6 to 11 mm ² /s. The total sulfur content is 0 to 0.03% by mass (0 to 300 ppm), preferably less than 0.01% by mass (100 ppm). The total nitrogen content is also less than 10 ppm, preferably less than 1 ppm, and the aniline point is 80 to 150°C, preferably 100 to 135°C.

GTL (gas liquid) base oil synthesized by the Fischer-Tropsch method of converting natural gas into liquid fuel has extremely low sulfur content and aromatic content compared with mineral oil base oil refined from crude oil, and paraffin. Since the composition ratio is extremely high, the oxidation stability is excellent, and the evaporation loss is also very small, so that it can be suitably used as the base oil in the present invention.
The viscosity property of this GTL base oil is not particularly limited, but generally, the viscosity index is 100 to 180, more preferably 100 to 150, and the kinematic viscosity at 100° C. is ² to 12 mm ² /s, more preferably 2 to. 9 mm ² /s.
Further, usually, the total sulfur content is less than 0.03 mass% (300 ppm), more preferably less than 10 ppm, and the total nitrogen content is less than 1 ppm. Such GTL base oil corresponds to API Group 3 base oil, and SHELL XHVI (registered trademark) can be mentioned as an example of the product.

This GTL base oil can be used as the whole base oil or as a part of the base oil. When it is used as a part, when it is used in an amount of 30% by mass or more, preferably 40% by mass or more, and more preferably 50% by mass or more of the total amount of the base oil, the performance of the lubricating oil composition is more preferable. can do.

Examples of the hydrocarbon-based synthetic oil include polyolefin having a kinematic viscosity of ² to 12 mm ² /s at 100° C., oligomers of ethylene and alpha olefin, alkylbenzene, alkylnaphthalene, alkyldiphenylalkane, and the like, and mixtures thereof. You can

The above-mentioned polyolefin includes polymers of various olefins or hydrides thereof. Any olefin may be used, and examples thereof include ethylene, propylene, butene, and α-olefins having 5 or more carbon atoms. In the production of polyolefin, one type of the above olefins may be used alone, or two or more types may be used in combination.
In particular, polyolefin called polyalphaolefin (PAO) having a kinematic viscosity at 100° C. of ² to 12 mm ² /s, polybutene, and the like are suitable, and this is a base oil belonging to Group 4. The polyalphaolefin may be a mixture of two or more kinds of synthetic oils.

Group 5 base oils include oxygen-containing esters, ether base oils, and other synthetic oils, but their high densities increase the absolute viscosity when used as a lubricating oil composition, which results in hydraulic operation. When used as oil, it causes pressure loss, and from the viewpoint of energy saving, it is preferable to avoid using the Group 5 base oil as the base oil of the present invention.

Of the above hydrocarbon-based base oils, the base oil having a kinematic viscosity at 100° C. of 2 mm ² /s or less has a small molecular weight, and therefore the flash point of the base oil is generally measured by the JIS K2265-4 COC method. ) Is low at 150° C. or lower, and NOACK (measured by ASTM D5800) is high, resulting in a large evaporation loss, which is not preferable for long-term bearing or lubrication of hydraulic operation.
When the kinematic viscosity at 100° C. is 15 mm ² /s or more, the low temperature viscosity of the lubricating oil composition (measured by ASTM D5293, ASTM D4684) becomes high, which is not preferable for high speed rotating bearings and hydraulic fluids.
When %CA is larger than 5 or %CP is smaller than 60, solubility and polarity of the base oil are improved, but heat/oxidation stability is deteriorated, which may not be preferable. When the sulfur content is more than 0.7% by mass, the thermal and oxidative stability of the final composition of the bearing oil or hydraulic fluid is reduced, and the corrosiveness against copper or aluminum alloy such as non-ferrous metal is not preferable. Will be seen.

Although the content of the base oil in the present lubricating oil composition is not particularly limited, it is in the range of 50 to 99% by mass, preferably 60 to 99% by mass, more preferably 70 to 99% by mass, based on the total amount of the lubricating oil composition. Good to use in.

Overbased metal salicylate is added to the base oil. This overbased metal salicylate is known as a metal-based detergent-dispersant, and the content of the metal element is 1% or more by weight, preferably 10% or less, more preferably 8% or less. Is.
Examples of the metal of the overbased metal salicylate include sodium and potassium as an alkali metal, and calcium and magnesium as an alkaline earth metal. Among them, calcium and magnesium are preferable, and calcium is particularly preferable.
The content of the overbased salicylate is not particularly limited, but in terms of the total amount of the composition, the amount of calcium is preferably 30 ppm or more, more preferably 50 ppm or more, and further preferably 70 ppm or more. On the other hand, the upper limit is preferably 100 ppm or less.
If the above content is less than 30 ppm, the required electric conductivity may not be obtained, and if it exceeds 100 ppm, the friction coefficient characteristics deteriorate, and in the case of a wet brake, braking failure may occur. There is.

The structure of the overbased metal salicylate is not particularly limited, but a metal salt of salicylic acid having an alkyl group having 1 to 30 carbon atoms is preferably used. Among them, those having 10 to 25 carbon atoms in the alkyl group are preferable, and those having 10 to 20 carbon atoms are more preferable from the viewpoint of improving conductivity and friction coefficient.

The above-mentioned overbased salt means a salt having a base number of metal salicylate of 150 mgKOH/g or more. This base number is determined according to JIS K2501 "Petroleum products and lubricating oils-Neutralization number test method". It means a base number measured by the perchloric acid method according to a potentiometric titration method.

Poly(meth)acrylate is added to the base oil. This poly(meth)acrylate is known as a viscosity index improver, and is, for example, a polymer or copolymer of one or more monomers selected from various (meth)acrylic acid esters or its water. Examples include so-called non-dispersion type poly(meth)acrylates such as additives.

The molecular weight of this poly(meth)acrylate is selected in consideration of shear stability. Specifically, the weight average molecular weight thereof is usually 5,000 to 200,000, preferably 10,000 to 50,000, and more preferably 30,000 to 40 in the case of non-dispersion type polymethacrylate. It is 1,000. The poly(meth)acrylate may contain one kind or two or more kinds having different molecular weights selected arbitrarily in an arbitrary amount.

Examples of the non-dispersion type poly(meth)acrylate include a polymer or copolymer of one or more monomers selected from the compounds represented by the following general formula (1), or a hydride thereof. it can.

In the general formula (1), R ¹¹ represents a hydrogen atom or a methyl group, and R ¹² represents an alkyl group having 1 to 18 carbon atoms. Specific examples of the alkyl group having 1 to 18 carbon atoms, which represents R ¹² , include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group and undecyl group. Examples thereof include a group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group and an octadecyl group, and these alkyl groups may be linear or branched.

Preferable examples of the monomer of the general formula (1) include specifically alkyl acrylates having 1 to 18 carbon atoms, alkyl methacrylates having 1 to 18 carbon atoms, olefins having 2 to 20 carbon atoms, styrene and methylstyrene. , Maleic anhydride and mixtures thereof.

The above-mentioned poly(meth)acrylate is usually provided in a diluted form to obtain a solution, and the content of the poly(meth)acrylate in the lubricating oil composition in that state is generally 0.1 based on the total amount of the composition. It is at least mass% and the upper limit is at most 10 mass%, preferably at most 8 mass%, more preferably at most 5 mass%. When the content is less than 0.1% by mass based on the total amount of the composition, it is difficult to obtain the effect of improving conductivity, while when it exceeds 10% by mass, the shear stability may be poor.
The above content is 0.07 to 2.0 mass% as the net amount of poly(meth)acrylate.

A phosphorus compound can be further added to the lubricating oil composition, which can further improve the wear resistance. Examples of such phosphorus compounds include zinc dithiophosphate and zinc phosphate.
These phosphorus compounds are added in an amount of about 0.01 to 0.10% by mass (100 to 1000 ppm) with respect to 100 parts by mass of the base oil, and the amount of phosphorus is preferably 0.1 based on the total amount of the lubricating oil. They can be used alone or in combination in the range of 01% (100 ppm) to 0.08% (800 ppm), more preferably 0.01 to 0.04% by mass.
In the case of zinc dithiophosphate, since the conductivity is low, if the phosphorus content is more than 0.08% by mass, the conductivity may be adversely affected, and if the phosphorus content is less than 0.01% by mass, the wear resistance will be poor. Sometimes it can't be maintained.

Examples of the above zinc dithiophosphate generally include zinc dialkyldithiophosphate, zinc diaryldithiophosphate, zinc arylalkyldithiophosphate and the like. As the hydrocarbon group, for example, the alkyl group may be a primary or secondary alkyl group having 3 to 12 carbon atoms, and the aryl group may be a phenyl group or a phenyl group substituted with an alkyl group having 1 to 18 carbon atoms. And an alkylaryl group.
Among these zinc dithiophosphates, zinc dialkyldithiophosphate having a primary alkyl group is preferable, and the alkyl group has 3 to 12 carbon atoms, and preferably 3 to 8 carbon atoms.

In the lubricating oil composition of the present invention, in order to further improve the performance in addition to the above-mentioned components, various additives can be appropriately used if necessary. As such additives, pour point depressants, antioxidants, extreme pressure agents, oiliness agents, metal deactivators, antiwear agents, antifoaming agents, viscosity index improvers, detergent dispersants, rust inhibitors, Examples thereof include antifoaming agents and other known lubricating oil additives.

As described above, the present lubricating oil composition has an electrical conductivity (electrical conductivity) of 200 pS/m or more at 25° C. (room temperature). In this case, if it is less than 200 pS/m, the ability to ground the accumulation of static electricity generated by flow electrification becomes low, and it becomes impossible to effectively prevent troubles caused by static electricity.
Further, since the flash point of this lubricating oil composition is set to 240° C. or higher, more preferably 250° C. or higher, it can be handled safely and the pour point is set to −40° C. or lower. It can sufficiently withstand use in the ground.

The viscosity of the present lubricating oil composition is not particularly limited, but the kinematic viscosity at 100° C. is preferably ² to 15 mm ² /s, preferably 4 to 15 mm ² /s, and more preferably 6 to 11 mm ² /s. The kinematic viscosity at 40° C. is 10 to 100 mm ² /s, preferably 15 to 100 mm ² /s, more preferably 22 to 100 mm ² /s, and further preferably 41 to 75 mm ² /s.
The viscosity grade of this lubricating oil composition may be VG46 to VG68, which is particularly convenient when used as a hydraulic fluid.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
The following materials were prepared in order to manufacture Examples and Comparative Examples.

Base oil 1: GTL (kinematic viscosity 40° C. 44.0 mm ² /s, viscosity index 143) and Group 1 base oil according to API classification (kinematic viscosity 40° C. 49.5 mm ² /s, viscosity index 103) Hydrocarbon-based base oil blended with 50% by mass of base oil 2: 40% by mass of GTL (kinematic viscosity 40° C. is 44.0 mm ² /s, viscosity index 143) and Group 1 base oil according to API classification (Kinematic viscosity 40° C. 49.5 mm ² /s, viscosity index 103) 60% by mass of a hydrocarbon-based base oil blended product Base oil 3: GTL (kinematic viscosity 40° C. 44.0 mm ² /s, Hydrocarbon base oil blend product in which 30 mass% of viscosity index 143) and 70 mass% of Group 1 base oil according to API classification (kinematic viscosity 40° C. 49.5 mm ² /s, viscosity index 103) were mixed.

Overbased Ca salicylate: M7121 (manufactured by Infinium Co., Ltd.) (property; base number 255 mgKOH/g, Ca amount 8%)
Neutral Ca Sulfonate: NaSul729 (manufactured by King Industries) (Property; Base number is 0, Ca content is 2.1%)
Overbased Ca Sulfonate: Oloa247E (manufactured by Oronite Co., Ltd.) (property; base number 330 mgKOH/g, Ca amount 12.75%)

PMA1: non-dispersion type polymethacrylate; Viscoplex 8-200 (manufactured by Evonik) (property; polymer concentration 72.5%, weight average molecular weight 33,000)
PMA2: non-dispersion type polymethacrylate; Aclube V815 (manufactured by Sanyo Kasei Co., Ltd.) (property; polymer concentration 60 to 70%, weight average molecular weight 20,000)
PMA3: non-dispersion type polymethacrylate; Aclube 504 (manufactured by Sanyo Kasei Co., Ltd.) (property; polymer concentration 35-45%, weight average molecular weight 180,000)

The weight average molecular weights of PMA1 to PMA3 are measured under the following measurement conditions.
・Measurement method: GPC (gel permeation chromatography)
The weight average molecular weight was calculated according to JIS K7252-1 "Plastics-Determination of average molecular weight and molecular weight distribution of polymer by size exclusion chromatography-Part 1: General rules".
・Measuring device: Shimadzu SIL20AHT
・Column used: Shodex LF604×2 ・Measuring temperature: 40°C

The following examples and comparative examples were produced.
(Example 1)
To 99.75 mass% of the above base oil 1, 0.05 mass% of overbased Ca salicylate and 0.20 mass% of PMA1 were added and mixed well to obtain a lubricating oil composition of Example 1. ..
(Examples 2 to 12)
Lubricating oil compositions of Examples 2 to 12 were obtained in the same manner as in Example 1 except that the compositions shown in Table 1 and Table 2 were used.

(Comparative Examples 1 to 15)
Lubricating oil compositions of Comparative Examples 1 to 15 were obtained in the same manner as in Example 1 except that the compositions shown in Tables 3 to 5 were used.

[Tests, etc.]
The following tests and the like were appropriately conducted in order to know the properties and performances of the above-mentioned Examples and Comparative Examples.
(Amount of Ca in oil)
Japan Petroleum Institute standard JPI-5S-38-03 Lubricating oil-Testing method for added elements-Ca amount contained in the lubricating oil composition was measured by inductively coupled plasma optical emission spectroscopy and expressed in ppm.
(Kinematic viscosity: 40°C kinematic viscosity)
The kinematic viscosity at 40° C. (mm ² /s) was measured based on JIS K2283.
In each of the example and the comparative example, it was set within the range of (46.0±10%) mm ² /s.
(Amount of polymer)
The amount of polymer due to PMA contained in the lubricating oil composition was calculated and expressed as% by mass.

(Electrical conductivity test)
The electrical conductivity was measured by the electrical conductivity test method described in 18 of JIS K2276 Petroleum Products-Aviation Fuel Oil Test Method.
Since the measured value will be affected if the sample temperature is not stable, the sample is left to stand in a thermostatic chamber kept at 25° C. for 12 hours or more, and then the sample is transferred from Emcee Electronics Inc. It measured using the electric conductivity meter Model 1152 made by the company.
The measured values are expressed in S-Siemens notation.
Evaluation criteria: Thing of 200 pS/m or more...Pass (○)
Less than 200 pS/m: Fail (x)

(Micro clutch test)
The micro-clutch test was carried out by using the friction test method with the micro-clutch tester described in JCMAS (Japan Construction Machinery Construction Association Standard) P047 Construction Machine Hydraulic Fluid-Friction Characteristic Test Method to determine the friction coefficient value at 140°C. Measured.
Evaluation criteria: A friction coefficient of 0.08 or more: Pass (○)
Coefficient of friction less than 0.08... Fail (x)

(Measurement of flash point)
The flash point was obtained by repeating the measurement three times for each sample of the example and the comparative example by the COC method/Cleveland open type automatic flash point measuring device according to JIS K2265-4, and calculating the average value by rounding to one decimal place. ..
Evaluation criteria: Flash point of 240°C or higher...Pass (○)
Those with a flash point of less than 240°C... Fail (x)
(Measurement of pour point)
The pour point was measured based on JIS K2269.
Evaluation criteria: Pour point of −40° C. or lower... Pass (○)
Pour point higher than -40℃・・・Failure (×)

(result)
The results of each of the above tests are shown in Tables 1-5.

(Discussion)
In Examples 1 to 5, base oil 1 was made to contain overbased Ca salicylate and PMA1, and all of them passed the electric conductivity, the friction coefficient of the micro clutch, the flash point, and the pour point. Good results have been obtained.
In Example 2, the amount of PMA1 added was 10 times that in Example 1, and the electrical conductivity was even better than in Example 1. In Example 3, the amount of the overbased Ca salicylate added was doubled as compared with Example 1, and the electric conductivity was improved as compared with Example 1, and in Examples 4 and 5, The amount of PMA1 added was 5 times or 10 times that of Example 3, and the electrical conductivity was further improved.

In Examples 6 and 7, the base oil 1 was made to contain the overbased Ca salicylate and PMA2, and all passed the electrical conductivity, the friction coefficient of the micro clutch, the flash point, and the pour point. Good results have been obtained. In Example 6, the electric conductivity was improved as compared with Example 3 due to the difference in PMA used, and when the amount of PMA2 added was increased as in Example 7, more preferable results were obtained than in Example 4.
In Examples 8 and 9, PMA3 was used, and the intermediate electric conductivity between Examples 3 and 4 and Examples 6 and 7 was obtained, but the results are good.

In Example 10, the amount of overbased Ca salicylate was increased as compared with Example 3, and thereby the electric conductivity was improved. In Example 11, the base oil 2 was used for the base oil 1 of Example 4, and it can be seen that the same preferable result as in Example 4 was obtained. In addition, Example 12 uses Base Oil 3 for Base Oil 1 of Example 4 and has a slightly lower flash point, but it is possible to obtain the same preferable result as in Example 4. I understand.

On the other hand, Comparative Example 1 was composed of Base Oil 1, Comparative Example 2 was prepared by adding only PMA1 to Base Oil 1, Comparative Example 3 was prepared by adding PMA2 only, and Comparative Example 4 was prepared by adding only PMA3. However, all of them have almost no electrical conductivity, which is not preferable.
Comparative Example 5 is a base oil 1 to which only neutral Ca sulfonate is added, and is not preferable because it has low electric conductivity and high pour point. Comparative Example 7 was prepared by adding only overbased Ca sulfonate to Base Oil 1, and the electric conductivity was improved as compared with Comparative Example 5, but the pour point was high and it has not yet passed. Comparative Example 6 is obtained by adding PMA1 to Comparative Example 7, and the pour point is acceptable, but the electrical conductivity is lowered, which is not preferable.
In addition, in Comparative Examples 1 to 7, since the electrical conductivity or the pour point did not pass, the micro clutch test was not performed.

In Comparative Example 8, the amount of overbased Ca salicylate was increased and added to the base oil 1, and although the electrical conductivity passed, the friction coefficient of the micro clutch and the pour point failed. .. Comparative Examples 9 and 10 are the same as Comparative Example 8 except that the amount of PMA1 was changed, and when the amount of overbased Ca salicylate was large, the friction coefficient of the micro clutch did not pass even if PMA was added, which is preferable. No results have been obtained.

In Comparative Examples 11 to 13, the overbased Ca salicylate was added to the base oil 1 in the same amount as in the Example, but since PMA was not contained, Comparative Examples 11 and 12 flowed. In the point of Comparative Example 13, the electrical conductivity and the pour point are unacceptable.
In Comparative Examples 14 and 15, the base oil 3 and the base oil 2 were used in place of the base oil 1 of the comparative example 11, and the electrical conductivity, the friction coefficient of the micro clutch, and the flash point passed, but In Example 14, the pour point was unacceptable, and in Comparative Example 15, the pour point was also unacceptable, and it can be seen that favorable results were not obtained.

Claims (5)

Hydrocarbon base oil, overbased calcium salicylate as a calcium content of 30 to 100 ppm with respect to the total amount of the composition, and a non-dispersed polymethacrylate having a weight average molecular weight of 5,000 to 200,000 as a net amount. A composition containing 0.07 to 2.0% by mass based on the total amount of the substances, wherein the composition has an electrical conductivity at 25° C. of 200 pS/m or more, a flash point of 240° C. or more, and a pour point of −. A hydraulic actuator equipped with an electronically controlled device, which has a friction coefficient (micro-clutch test method) at 40°C or less and 140°C of 0.08 or more and does not contain an ashless friction modifier and an azo compound. Lubricating oil composition. The lubricating oil composition for hydraulic actuators having an electronic control device according to claim 1, wherein the hydrocarbon-based base oil includes a gas to liquid (GTL) base oil. The lubricating oil composition for hydraulic actuators according to claim 2, wherein the hydrocarbon base oil contains 40 mass% or more of gas liquid (GTL) base oil. The viscosity grade of the composition is VG46-68, The lubricating oil composition for hydraulic actuators with the electronic control device according to any one of claims 1-3. Furthermore, zinc dialkyldithiophosphate is contained as a phosphorus content in an amount of 100 to 1000 ppm with respect to the total amount of the composition, and the kinematic viscosity of the composition at 40° C. is 10 to 100 mm ² /s. A lubricating oil composition for a hydraulic actuator, comprising the electronic control device according to any one of 1.