JP2017178974A - Lubricating oil composition for hydraulic actuator comprising electronically controlled equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricating oil composition for a hydraulic actuator, which is given electrical conductivity for preventing generation of noise adversely affecting a device having a hydraulic circuit comprising an electronically controlled equipment of a valve system and which is excellent in safety.SOLUTION: The lubricating oil composition for a hydraulic actuator is provided that employs hydrocarbon-based base oil and contains superbasic calcium salicylate of 30 to 300 ppm as calcium content based on total amount of the composition and non-dispersible polymethacrylate having a weight average molecular weight of 5,000 to 200,000 of 0.07 to 2.0 mass% based on total amount of the composition as net amount in the base oil. Electrical conductivity of the composition at 25°C is 200 pS/m or more, flash point is 240°C or more, pour point is -40°C or less and friction coefficient of a micro clutch at 140°C is 0.08 or more. The lubricating oil composition can be given electrical conductivity for preventing generation of noise adversely affecting electronic control by being used in a machine comprising electronically controlled equipment.SELECTED DRAWING: None

Description

  The present invention relates to a lubricating oil composition for a hydraulic actuator having electrical conductivity that does not 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 a long time (Non-patent Document 1) that when such a liquid is fed through a pipe or the like, static electricity is generated (referred to as flow electrification).
The electric charge generated at this time is carried to the storage tank together with the liquid, and a spark is generated by charging and discharging inside or around the tank container, which may ignite the liquid. In order to prevent the occurrence of sparks by suppressing the accumulation of static electricity against such a phenomenon, for example, STADIS- containing dinonylnaphthyl sulfonic acid, which increases electrical conductivity (conductivity, electric conductivity), as an active ingredient It is known to add 450 (manufactured by DuPont).

  Furthermore, in recent years, the risk of generating static electricity due to oil feeding at a higher speed is increasing due to the higher performance of hydraulic devices. Sparks generated by an electrical phenomenon generated at the interface between a solid and oil such as a storage tank become noise, causing a problem of causing malfunction or failure to a control device including electronic components.

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 functions to lubricate sliding portions.
Recent hydraulic equipment has been reduced in size and increased in output, and the operating pressure has been increased from about 14 to 20 MPa, for example, to 30 MPa or more at present, and the oil feeding speed is also increased. Therefore, the possibility of occurrence of fluid charging is further increased.
Since these hydraulic systems are usually equipped with electronically controlled valve systems, it is desirable to take measures to prevent spark noise and to have a high flash point from the standpoint of safety when stored. Moreover, when using for lubrication of a wet brake, it is calculated | required that it has a moderate friction coefficient so that there may be no braking failure.

In order to improve the conductivity of the lubricating oil composition, those having a strong polar group and a suitable size of lipophilic group in the molecule, such as organometallic compounds, succinic acid derivatives or amine derivatives, and aromatic azo compounds A combination of compounds that is contained in a base oil is known. In this product, volume resistivity of 1 × 10 ¹⁰ Ω · cm or less is judged to be acceptable, but this is equivalent to 10 pS / m or more in the S-Siemens notation, and the occurrence of sparks due to fluid charging is ensured. It was still not enough to prevent it. In addition, since the aromatic azo compound is an essential component, the lubricating oil is red, and it is difficult to determine the deterioration of the lubricating oil by visual observation on site, and the braking characteristics are not taken into consideration. (Patent Document 1)

JP 2001-234187 A

Aichi Institute of Technology Research Report B Technical Papers 14, 1-6, “Liquid Capillary Flow Charging” March 31, 1979

  The present invention provides conductivity to prevent the generation of noise that adversely affects electronic control devices such as electronically controlling a valve system, and is excellent in braking characteristics of a wet brake that is electronically controlled. It is an object of the present invention to provide a lubricating oil composition for a hydraulic actuator having excellent properties.

  In the present invention, a hydrocarbon base oil is used as a base oil, and an overbased calcium salicylate is used as a calcium content in the base oil, and the weight-average molecular weight is 5,000 to 200,000 with respect to the total amount of the composition. This is a composition containing 0.07 to 2.0% by mass based on the total amount of the non-dispersed polymethacrylate as a net amount. The conductivity at 25 ° C. of this composition 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 microclutch test method at 140 ° C. The lubricating oil composition is used for a hydraulically operated machine provided with an electronic control device having a friction coefficient of 0.08 or more.

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

  The lubricating oil composition of the present invention can be made highly conductive, has a low pour point, has a low flow charge, can prevent ignition associated with static charge, and has a high flash point. It can be used safely and safely, it prevents the occurrence of noise that adversely affects electronic control equipment such as electronically controlling the valve system, and it has excellent braking characteristics for electronically controlled wet brakes. It can be set as the lubricating oil composition for motives.

In the present invention, a hydrocarbon base oil is used as the base oil.
This hydrocarbon base oil is a base oil belonging to Group 1, Group 2, Group 3, and Group 4 in the API (American Petroleum Institute, American Petroleum Institute) base oil category. It is a mixture.

The Group 1 base oil can be obtained, for example, by applying a suitable combination of solvent purification, hydrorefining, dewaxing and other purification means to a lubricating oil fraction obtained by atmospheric distillation of crude oil. And paraffinic mineral oils.
The Group 1 base oil used here has a kinematic viscosity at 100 ° C. (measured according to ASTM D445, JIS K2283, the same shall apply hereinafter) of ² to 15 mm ² / s, preferably 4 to 15 mm ² / s, 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. Further, 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. The% CA according to ASTM D3238 is 5 or less, preferably 4 or less, more preferably 3.4 or less, and the% CP is 60 or more, preferably 63 or more, more preferably 66 or more.

As Group 2 base oils, for example, paraffinic oils obtained by appropriately combining refining means such as hydrocracking and dewaxing for lubricating oil fractions obtained by atmospheric distillation of crude oil Mention may be made of mineral oil. Group 2 base oils refined by hydrorefining methods such as the Gulf Company method have 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 mass% (300 ppm), preferably less than 0.02 mass% (200 ppm), and more preferably less than 0.001 mass% (10 ppm). The total nitrogen content is also less than 10 ppm, preferably less than 1 ppm. Furthermore, an aniline point (measured according to ASTM D611, JIS K2256) is 80 to 150 ° C, preferably 100 to 135 ° C.

In addition, paraffinic mineral oil produced by advanced hydrorefining and ISODEWAX that converts and dewaxes wax produced in the dewaxing process into isoparaffin for the lubricating oil fraction obtained by atmospheric distillation of crude oil A base oil refined by a process and a base oil refined by a mobile WAX isomerization process can also be suitably 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 still more preferably 6 to 11 mm ² / s. The total sulfur content is 0 to 0.03 mass% (0 to 300 ppm), preferably less than 0.01 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 Liquid) base oil synthesized by the Fischer-Tropsch method, which is a natural gas liquid fuel technology, has extremely low sulfur and aromatic content compared to mineral oil base oil refined from crude oil. Since the composition ratio is extremely high, the oxidation stability is excellent and the evaporation loss is very small. Therefore, 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 usually 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 2. 9 mm ² / s.
In general, 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 a GTL base oil corresponds to an API group 3 base oil, and SHELL XHVI (registered trademark) can be given as an example of a product.

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

Examples of the hydrocarbon-based synthetic oil include polyolefins having a kinematic viscosity at 100 ° C. of ² to 12 mm ² / s, oligomers of ethylene and alpha olefins, alkylbenzenes, alkylnaphthalenes, alkyldiphenylalkanes, and mixtures thereof. Can do.

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

  Group 5 base oils include oxygenated esters, ether base oils, and other synthetic oils, but these oils have high density, which increases the absolute viscosity when used as a lubricating oil composition. When used as an oil, it causes pressure loss, and from the viewpoint of energy saving, it is preferable to avoid using Group 5 base oils as base oils of the present invention.

In the above hydrocarbon base oils, base oils having a kinematic viscosity at 100 ° C. of 2 mm ² / s or less are generally low in molecular weight. Therefore, the base oil flash point (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 lubrication of bearings and hydraulic operation.
When the kinematic viscosity at 100 ° C. is 15 mm ² / s or more, the low temperature viscosity (measured by ASTM D5293 and ASTM D4684) of the lubricating oil composition increases, which is not preferable for high-speed bearings and hydraulic fluids.
On the other hand, when% CA is larger than 5 or% CP is smaller than 60, the solubility and polarity of the base oil are improved, but the thermal / oxidation stability may be lowered, which may be undesirable. If the sulfur content is more than 0.7% by mass, the heat and oxidation stability of the final composition, such as bearing oil and hydraulic fluid, will decrease, and this is an undesirable phenomenon in the corrosiveness to non-ferrous metals such as copper and aluminum alloys. Can be seen.

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

Overbased metal salicylate is added to the base oil. This overbased metal salicylate is known as a metal detergent and has a metal element content of 1% or more by weight, preferably 10% or less, more preferably 8% or less. It is.
Examples of the metal of the overbased metal salicylate include sodium and potassium for alkali metals, and calcium and magnesium for alkaline earth metals. Of these, calcium and magnesium are preferable, and calcium is particularly preferable.
The content of this overbased salicylate is not particularly limited, but is preferably 30 ppm or more, more preferably 50 ppm or more, and still more preferably 70 ppm or more in terms of calcium based on the total amount of the composition. On the other hand, the upper limit is preferably 300 ppm or less, more preferably 250 ppm or less, and even more preferably 200 ppm or less.
When the content is less than 30 ppm, the required electrical conductivity may not be obtained. When the content exceeds 300 ppm, the friction coefficient characteristics deteriorate, and in the case of a wet brake, there is a risk of causing braking failure. is there.

  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 these, those having 10 to 25 carbon atoms in the alkyl group are preferable, and more preferably 10 to 20 in view of improving conductivity and coefficient of friction.

  The above-described overbased salt refers to a metal salicylate having a base number of 150 mgKOH / g or more. This base number is determined according to JIS K2501 “Petroleum products and lubricants—neutralization number test method”. It means the base number by the perchloric acid method measured according to the potentiometric titration method.

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

  The molecular weight of the poly (meth) acrylate is selected in consideration of shear stability. Specifically, for example, in the case of non-dispersed polymethacrylate, the weight average molecular weight is usually 5,000 to 200,000, preferably 10,000 to 50,000, more preferably 30,000 to 40. 1,000. The poly (meth) acrylate can contain one or two or more arbitrarily selected ones having different molecular weights in any amount.

  Examples of the non-dispersed poly (meth) acrylate include a polymer, copolymer or hydride of one or more monomers selected from compounds represented by the following general formula (1). 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 representing R ¹² include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, and undecyl. Group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group and the like can be exemplified, and these alkyl groups may be linear or branched.

  Preferable examples of the monomer of the general formula (1) component are 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, methylstyrene. , Maleic anhydride and mixtures thereof.

The poly (meth) acrylate is usually provided after being diluted to form a solution. In that state, the content in the lubricating oil composition is generally 0.1 based on the total amount of the composition. The upper limit is 10% by mass or less, preferably 8% by mass or less, and more preferably 5% by mass or less. 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 the conductivity, while when it exceeds 10% by mass, the shear stability may be inferior.
Said content is 0.07-2.0 mass% as net amount of poly (meth) acrylate.

A phosphorus compound can be further added to the lubricating oil composition, thereby further improving the wear resistance. Examples of such phosphorus compounds include zinc dithiophosphate and zinc phosphate.
These phosphorus compounds are blended 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. It 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, the conductivity is low, so if the amount of phosphorus exceeds 0.08% by mass, the conductivity may be adversely affected. If the amount of phosphorus is less than 0.01% by mass, the wear resistance will be low. It may not be maintained.

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

  In addition to the above-described components, various additives can be appropriately used as necessary in the lubricating oil composition of the present invention in order to further improve performance. These additives include ashless friction modifiers (eg monoglycerides), pour point depressants, antioxidants, extreme pressure agents, oil improvers, metal deactivators, antiwear agents, antifoaming agents, viscosity index. Examples include improvers, detergent dispersants, rust inhibitors, antifoaming agents, and other known lubricating oil additives.

As described above, the lubricating oil composition has a conductivity (conductivity) at 25 ° C. (room temperature) of 200 pS / m or more. In this case, if it is less than 200 pS / m, the ability to ground the accumulation of static electricity generated by the flow charge becomes low, and troubles caused by static electricity cannot be effectively prevented.
Further, as described above, the flash point of this lubricating oil composition is 240 ° C. or higher, more preferably 250 ° C. or higher, so that it can be handled safely and the pour point is −40 ° C. or lower. It can sufficiently withstand use on the ground.

The viscosity of the 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. Moreover, kinematic viscosity in 40 degreeC is 10-100 mm < ² > / s, Preferably it is 15-100 mm < ² > / s, More preferably, it is 22-100 mm < ² > / s, More preferably, it is 41-75 mm < ² > / s.
The viscosity grade of the lubricating oil composition may be VG46 to VG68, which is particularly convenient when used as a hydraulic fluid.

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated concretely, this invention is not limited at all by this.
In order to produce Examples and Comparative Examples, the following materials were prepared.

Base oil 1: 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. is 49.5 mm ² / s, viscosity index is 103) Base oil 2: GTL (kinematic viscosity 40 ° C is 44.0 mm ² / s, viscosity index 143) is 40% by mass, group 1 base oil according to API classification (Base material 3: GTL (dynamic viscosity 40 ° C. is 44.0 mm ² / s), blended at 60% by mass (kinematic viscosity 40 ° C. is 49.5 mm ² / s, viscosity index is 103) Hydrocarbon base oil blend product in which 30% by mass of viscosity index 143) and 70% by mass of group 1 base oil according to API classification (kinematic viscosity 40 ° C. 49.5 mm ² / s, viscosity index 103)

Overbased Ca salicylate: M7121 (manufactured by Infinium) (property; base number is 255 mgKOH / g, Ca content is 8%)
Neutral Ca sulfonate: NaSul729 (manufactured by King Industry) (property; base number is 0, Ca content is 2.1%)
Overbased Ca sulfonate: Oloa247E (manufactured by Oronite) (property; base number is 330 mgKOH / g, Ca content is 12.75%)

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

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 using JIS K7252-1 "Plastics-Determination of average molecular weight and molecular weight distribution of polymer by size exclusion chromatography-Part 1: General rules".
・ Measurement device: SIL20AHT manufactured by Shimadzu Corporation
-Column used: Shodex LF604 x 2-Measurement temperature: 40 ° C

The following examples and comparative examples were prepared.
Example 1
To 99.75% by mass of the base oil 1, 0.05% by mass of overbased Ca salicylate and 0.20% by mass of PMA1 were added and mixed well to obtain the lubricating oil composition of Example 1. .
(Examples 2 to 12)
Other than the compositions described in Tables 1 and 2, the lubricating oil compositions of Examples 2 to 12 were obtained in the same manner as in Example 1.

(Comparative Examples 1-15)
Other than the compositions described in Tables 3 to 5, the lubricating oil compositions of Comparative Examples 1 to 15 were obtained in the same manner as in Example 1.

[Examination]
In order to know the properties and performance of the above examples and comparative examples, the following tests were conducted as appropriate.
(Ca content in oil)
Petroleum Society Standard JPI-5S-38-03 Lubricating Oil-Additive Element Test Method-The amount of Ca contained in the lubricating oil composition was measured by inductively coupled plasma optical emission spectrometry and displayed in ppm.
(Kinematic viscosity: 40 ° C kinematic viscosity)
Based on JIS K2283, 40 degreeC kinematic viscosity (mm < ² > / s) was measured.
In the examples and comparative examples, both were within the range of (46.0 ± 10%) mm ² / s.
(Polymer amount)
It calculated about the polymer amount by PMA contained in a lubricating oil composition, and displayed with the mass%.

(Electrical conductivity test)
The electrical conductivity was measured by the conductivity test method described in 18 of JIS K2276 Petroleum product-aviation fuel oil test method.
Since the measurement value is affected if the sample temperature is not stable, the sample is left standing in a temperature-controlled room maintained at 25 ° C. for 12 hours or more, and then US-based Electronics Inc., USA. It measured using the electric conductivity meter Model 1152 by a company.
The measured value was expressed in S Siemens notation.
Evaluation criteria: 200 pS / m or more: Pass (○)
Less than 200 pS / m ... Fail (×)

(Micro clutch test)
The micro-clutch test was performed using a friction test method with a micro-clutch tester described in JCMAS (Japanese Construction Machinery Construction Association Standard) P047 Hydraulic Hydraulic Fluids for Construction Machinery-Friction Characteristics Test Method. Measured.
Evaluation criteria: Friction coefficient of 0.08 or more: Pass (○)
Friction coefficient less than 0.08 ... Fail (×)

(Measure flash point)
The flash point was measured 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 JISK2265-4, and the average value was obtained by rounding off one decimal place. .
Evaluation criteria: flash point of 240 ° C. or higher.
Those with a flash point of less than 240 ° C ... Fail (×)
(Measure 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 ° C ... Fail (x)

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

(Discussion)
In Examples 1 to 5, the base oil 1 contains overbased Ca salicylate and PMA1, and all passed in electrical conductivity, friction coefficient of microclutch, flash point, and pour point. Good results have been obtained.
In Example 2, the amount of PMA1 added is 10 times that in Example 1, and the electrical conductivity is further improved compared to Example 1. In Example 3, the amount of overbased Ca salicylate added was doubled compared to Example 1, and the electrical conductivity was improved compared to Example 1, and those in Examples 4 and 5 were In addition, the amount of PMA1 added is 5 times and 10 times that of Example 3, and the electrical conductivity is further improved.

In Examples 6 and 7, the base oil 1 contains overbased Ca salicylate and PMA2, and all passed in electrical conductivity, friction coefficient of microclutch, flash point, and pour point. Good results have been obtained. In Example 6, the electrical conductivity is improved as compared with Example 3 due to the difference in PMA used. When the amount of PMA2 added is increased as in Example 7, a more preferable result is obtained than in Example 4.
In Examples 8 and 9, PMA3 was used, and an intermediate electrical conductivity between Examples 3 and 4 and Examples 6 and 7 was obtained, but good results.

  In Example 10, the amount of overbased Ca salicylate was increased as compared to Example 3, which improved the electrical conductivity. In Example 11, the base oil 2 was used with respect to the base oil 1 of Example 4, and it can be seen that the same preferable results as in Example 4 were obtained. Moreover, Example 12 uses the base oil 3 with respect to the base oil 1 of Example 4, and although a flash point is a little low, this preferable result substantially the same as Example 4 is obtained. I understand.

On the other hand, Comparative Example 1 is composed of base oil 1, Comparative Example 2 is the base oil 1 with only PMA1, Comparative Example 3 with only PMA2, and Comparative Example 4 with only PMA3. These are not preferable because they have almost no electrical conductivity.
In Comparative Example 5, only the neutral Ca sulfonate is added to the base oil 1, and the electrical conductivity is low and the pour point is high, which is not preferable. In Comparative Example 7, only the overbased Ca sulfonate was added to the base oil 1 and the electrical conductivity was improved as compared with Comparative Example 5. However, the pour point was high and it was not yet passed. In Comparative Example 6, PMA1 is added to Comparative Example 7, and the pour point is passed, but the electrical conductivity is lowered, which is not preferable.
In Comparative Examples 1 to 7, the electrical conductivity or pour point did not pass, so the microclutch test was not performed.

  In Comparative Example 8, the amount of overbased Ca salicylate was increased and added to the base oil 1, and the electrical conductivity passed, but the microclutch friction coefficient and pour point failed. . Comparative Examples 9 and 10 were added to Comparative Example 8 by changing the amount of PMA1, and when the amount of overbased Ca salicylate is large, the friction coefficient of the microclutch is not passed even if PMA is added, which is preferable. The result is not obtained.

In Comparative Examples 11 to 13, an overbased Ca salicylate was added to the base oil 1 in the same amount as in the Examples, but since PMA was not included, the fluids in Comparative Examples 11 and 12 In the comparative example 13, it is rejected by electrical conductivity and a pour point.
In Comparative Examples 14 and 15, base oil 3 and base oil 2 were used instead of base oil 1 in Comparative Example 11, and the electrical conductivity, the friction coefficient of the micro clutch, and the flash point passed, In Example 14, the pour point is unacceptable, and in Comparative Example 15, the pour point is also unacceptable, indicating that a preferable result is not obtained.

Claims (5)

  A composition comprising a hydrocarbon base oil, an overbased calcium salicylate as a calcium content, a non-dispersed polymethacrylate having a weight average molecular weight of 5,000 to 200,000 and a net amount of 30 to 300 ppm relative to the total amount of the composition A composition containing 0.07 to 2.0% by mass relative to the total amount, 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 −40. A lubricating oil composition for a hydraulic actuator provided with an electronic control device characterized in that the coefficient of friction at 140 ° C. or lower and a microclutch test method is 0.08 or higher.   The said hydrocarbon base oil contains a gas liquid (GTL) base oil, The lubricating oil composition for hydraulic actuators which arranged the electronic control apparatus of Claim 1 characterized by the above-mentioned.   The lubricating oil composition for a hydraulic operating machine provided with the electronic control device according to claim 2, wherein the hydrocarbon base oil contains 40% by mass or more of a gas triliquid (GTL) base oil.   The lubricating oil composition for a hydraulic actuator provided with the electronic control device according to any one of claims 1 to 3, wherein the viscosity grade of the composition is VG 46 to 68. Furthermore, zinc dialkyldithiophosphate is contained in an amount of 100 to 1000 ppm based on the total amount of the phosphorus as a phosphorus amount, and the kinematic viscosity at 40 ° C. of the composition is 10 to 100 mm ² / s. A lubricating oil composition for a hydraulic actuator provided with the electronic control device according to any one of the above.