WO2018186283A1 - Hydraulic device and hydraulic oil composition - Google Patents

Abstract

Provided is a hydraulic device comprising: an oil storage unit storing a hydraulic oil composition; a pressure feed unit that pressure-feeds the hydraulic oil composition; a control unit that controls the oil pressure, direction of flow, or flow rate of the hydraulic oil composition that has been pressure-fed; and a conversion unit that converts the controlled hydraulic oil composition oil pressure into mechanical power. The hydraulic oil composition contains: a lubricant base oil; an antioxidant including a phenol-based antioxidant; and a lubricant oil additive including at least one type selected from the group consisting of an organic molybdenum compound and a sulfur compound including sulfur as a constituent element thereof and not including molybdenum or phosphorus.

Description

Hydraulic device and hydraulic fluid composition

The present invention relates to a hydraulic device and a hydraulic fluid composition.

The hydraulic device is a device that transmits energy of an engine or the like as oil (hydraulic hydraulic oil) pressure, and is used in industrial machines such as iron making machines and construction machines. The hydraulic device includes, for example, a hydraulic pump, a control valve, a hydraulic cylinder, and the like. Since these components have sliding portions, the hydraulic fluid also plays a role as a lubricant for the sliding portions. Therefore, the hydraulic fluid is required to have characteristics as a lubricant such as lubricity and heat / antioxidation properties.

Hydraulic oil generally contains a lubricating base oil and an additive selected according to the required characteristics as described above. Examples of the additive include zinc-based antioxidants (zinc-based antiwear agents) such as zinc dithiophosphate. For example, Patent Document 1 discloses a hydraulic fluid composition containing a predetermined amount of zinc dithiophosphate.

JP 2000-219889 A

However, since zinc-based antioxidants can cause sludge, hydraulic fluids that do not contain zinc-based antioxidants have recently been required.

On the other hand, according to the study by the present inventors, when a hydraulic fluid containing no zinc-based antioxidant is used, lower carboxylic acids such as formic acid and acetic acid are likely to be generated with the deterioration of the hydraulic fluid. It has been found that rusting may occur in the oil filter that purifies the hydraulic fluid, the oil tank that stores the hydraulic fluid, and the like due to evaporation of the lower carboxylic acid.

An object of the present invention is to provide a hydraulic fluid composition capable of suppressing the generation of lower carboxylic acid, and a hydraulic device using the hydraulic fluid composition.

The present invention controls an oil storage unit in which a hydraulic fluid composition is stored, a pressure feeding unit that pumps the hydraulic fluid composition, and a hydraulic pressure, a flow direction, or a flow rate of the fed hydraulic fluid composition. A hydraulic device comprising: a control unit; and a conversion unit that converts the hydraulic pressure of the controlled hydraulic fluid composition into mechanical power, the hydraulic fluid composition comprising a lubricating base oil, a phenol-based oxidation It contains at least one selected from the group consisting of an antioxidant containing an antioxidant, an organic molybdenum compound, and a sulfur compound containing sulfur as a constituent element and not containing molybdenum and phosphorus (hereinafter also simply referred to as “sulfur compound”). And a lubricating oil additive.

The content of the organic molybdenum compound may be 50 mass ppm or less in terms of molybdenum element based on the total amount of the hydraulic fluid composition.

The organic molybdenum compound may be at least one selected from the group consisting of molybdenum dithiocarbamate and molybdenum dithiophosphate.

The sulfur compound may be at least one selected from the group consisting of sulfurized esters and sulfurized olefins.

Lubricating oil additive may contain both an organic molybdenum compound and a sulfur compound. That is, the hydraulic fluid composition may contain a lubricating oil additive that includes both an organic molybdenum compound and a sulfur compound.

The hydraulic fluid composition may further contain an ashless dispersant. Moreover, the hydraulic fluid composition may further contain a metallic detergent. Further, the hydraulic fluid composition may further contain an extreme pressure agent containing sulfur and phosphorus as constituent atoms and not containing molybdenum and zinc (hereinafter, also simply referred to as “sulfur-phosphorus extreme pressure agent”). Good.

The present invention also provides the above hydraulic fluid composition.

The present invention may further relate to the use (application) of the above composition as a hydraulic oil and the use (application) for the production of hydraulic oil.

According to the present invention, it is possible to provide a hydraulic fluid composition capable of suppressing the generation of lower carboxylic acid, and a hydraulic device using the hydraulic fluid composition. Moreover, the hydraulic fluid composition according to some embodiments is excellent in terms of reducing the amount of sludge. Furthermore, the hydraulic fluid composition according to some embodiments is excellent in terms of seizure resistance.

It is a figure which shows the hydraulic device which concerns on one Embodiment.

Hereinafter, embodiments of the present invention will be described in detail.

FIG. 1 is a diagram illustrating a hydraulic apparatus according to an embodiment. As shown in FIG. 1, a hydraulic device 1 according to an embodiment includes an oil storage unit 2 in which a hydraulic fluid composition is stored, a pumping unit 3 that pumps the hydraulic fluid composition, and a hydraulic fluid composition. A filtration unit 4 for purifying the fluid by filtration, a control unit 5 for controlling the hydraulic pressure, flow direction or flow rate of the hydraulic fluid composition, and a conversion unit 6 for converting the hydraulic pressure of the hydraulic fluid composition into mechanical power. Is provided with a hydraulic circuit.

The oil storage unit 2 includes, for example, a first oil tank 2A, a second oil tank 2B, and a third oil tank 2C. These oil tanks may be the same oil tank or may be separate oil tanks.

The pumping unit 3 is driven by, for example, an electric motor 7 and pumps a hydraulic fluid composition from the first oil tank 2A to generate hydraulic pressure. The pressure feeding unit 3 may be a hydraulic pump. Examples of the hydraulic pump include a gear pump, a screw pump, a vane pump, and a plunger pump. The hydraulic pressure generated by the pumping unit 3 is, for example, 5 to 50 MPa.

The filtration unit 4 includes, for example, a first filter 4A and a second filter 4B. The first filter 4A is provided between the first oil tank 2A and the pumping unit 3, and filters out foreign matters such as rust in the hydraulic fluid composition pumped from the first oil tank 2A. To remove.

The control unit 5 controls the hydraulic pressure, the direction of flow, or the flow rate of the hydraulic fluid composition pumped by the pumping unit 3. The control unit 5 includes, for example, a pressure control valve 8 that controls the hydraulic pressure, a direction control valve 9 that controls the direction of flow, and a flow control valve 10 that controls the flow rate.

For example, the pressure control valve 8 adjusts the hydraulic pressure generated by the pressure feeding unit 3 or, when the pressure measured by the pressure gauge 11 exceeds a certain level, a part of the hydraulic fluid composition is supplied to the second oil tank Escape to 2B. The pressure control valve 8 may be a relief valve, a pressure reducing valve, an unloader valve, a sequence valve, a counter balance valve, or the like.

The direction control valve 9 is composed of, for example, an electromagnetic switching valve 12 and a check valve 13. The electromagnetic switching valve 12 is connected to a first flow path 14 and a second flow path 15 that form a flow path to the conversion unit 6 and the third oil tank 2C. For example, a flow rate control valve 10 and a check valve 13 are provided in the first flow path 14. The second flow path 15 is in direct communication with the conversion unit 6, for example. The third oil tank 2C is connected to the electromagnetic switching valve 12 through, for example, the second filter 4B.

The electromagnetic switching valve 12 can switch the flow path to the conversion section 6 of the hydraulic fluid composition pumped from the pumping section 3 to either the first flow path 14 or the second flow path 15. Yes. For example, the hydraulic fluid composition sent from the electromagnetic switching valve 12 to the first flow path 14 returns to the electromagnetic switching valve 12 from the second flow path 15 via the conversion unit 6, and the second filter After foreign matter such as rust is filtered in 4B, it is sent to the third oil tank 2C. The direction control valve 9 may be configured by a switching valve such as a manual type or a mechanical type instead of the electromagnetic switching valve 12. The check valve 13 is provided in the first flow path 14, and prevents the backflow by flowing the hydraulic fluid composition in only one direction.

The flow control valve 10 may be, for example, a throttle valve, a flow adjustment valve, or the like. These valves may have a built-in deceleration valve. The conversion unit 6 converts the hydraulic pressure into power according to the flow rate controlled by the flow rate control valve 10, for example. The conversion unit 6 may be a hydraulic cylinder, a hydraulic motor, or the like. When the flow rate control valve 10 controls the flow rate of the hydraulic fluid composition, the moving speed of the hydraulic cylinder, the hydraulic motor, etc. (converter 6) can be adjusted. The hydraulic cylinder may be a single acting type, a double acting type, a special type, or the like. The hydraulic motor may be a gear motor, a vane motor, a plunger motor, or the like.

Next, the hydraulic fluid composition used in the hydraulic device will be described. The hydraulic fluid composition is at least selected from the group consisting of a lubricating base oil, an antioxidant containing a phenolic antioxidant, an organic molybdenum compound and a sulfur compound containing sulfur as a constituent element and not containing molybdenum and phosphorus. And a lubricating oil additive including one kind.

The hydraulic fluid composition contains a lubricating base oil. The lubricating base oil is, for example, mineral oil, synthetic oil, or a mixture of both. As mineral oils, lubricating oil fractions obtained by atmospheric distillation and vacuum distillation of crude oil are removed from solvents, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing, clay. Examples thereof include paraffinic and naphthenic mineral oils, normal paraffins, isoparaffins, and the like, which are purified by combining purification treatments such as treatment alone or in combination of two or more. These mineral oils may be used alone or in combination of two or more at any ratio.

Preferred base oils include the following base oils.
(1) Distilled oil obtained by atmospheric distillation of paraffin-based crude oil and / or mixed-base crude oil (2) Vacuum-distilled distilled oil (WVGO) of atmospheric distillation residue oil of paraffin-based crude oil and / or mixed-base crude oil )
(3) Wax obtained by lubricating oil dewaxing step and / or Fischer-Tropsch wax produced by GTL process or the like (4) One or more mixed oils selected from the above (1) to (3) Mild hydrocracking oil (MHC)
(5) Mixed oil of two or more oils selected from the above (1) to (4) (6) Detachment of (1), (2), (3), (4) or (5) Oil (DAO)
(7) Mild hydrocracking treatment oil (MHC) of (6) above
(8) A mixed oil of two or more kinds of oils selected from the above (1) to (7) is used as a raw oil, and this raw oil and / or a lubricating oil fraction recovered from this raw oil is usually used. Oil obtained by refining by the refining method and recovering the lubricating oil fraction

Here, as a normal refining method, a refining method used in base oil production can be arbitrarily adopted. Examples of normal purification methods include the following purification methods.
(A) Hydrorefining, such as hydrocracking, hydrofinishing, etc. (b) Solvent refining, such as furfural solvent extraction (c) Dewaxing, such as solvent dewaxing, catalytic dewaxing, etc. (d) White clay with acid clay, activated clay, etc. Purification (e) Chemical (acid or alkali) purification such as sulfuric acid washing, caustic soda washing, etc. These purifications may be carried out in any order by one or two or more arbitrary combinations.

Examples of synthetic oils include esters, ethers, hydrocarbon oils, and the like. These synthetic oils may be used alone or in combination of two or more at any ratio.

The ester may be, for example, an ester of a fatty acid (monobasic acid) and an alcohol or an ester of a polybasic acid and an alcohol.

The fatty acid may be a saturated fatty acid or an unsaturated fatty acid. The fatty acid may be, for example, a fatty acid having 2 to 24 carbon atoms. The fatty acid may be linear or branched. Examples of polybasic acids include dibasic acids and tribasic acids. The polybasic acid may or may not have an unsaturated bond. The polybasic acid may have 2 to 16 carbon atoms, for example. The dibasic acid may be linear or branched.

The alcohol may be a monohydric alcohol or a polyhydric alcohol. The carbon number of the monohydric alcohol may be, for example, 1 to 24, 1 to 12, or 1 to 8. The monohydric alcohol may be linear or branched. The number of hydroxyl groups possessed by the polyhydric alcohol (polyol) may be, for example, 2 to 10 or 2 to 6.

Examples of the ether include polyoxyalkylene glycol, dialkyl diphenyl ether, polyphenyl ether and the like.

Examples of the hydrocarbon oil include poly-α-olefin or a hydride thereof, isobutene oligomer or a hydride thereof, isoparaffin, alkylbenzene, alkylnaphthalene and the like.

The kinematic viscosity at 40 ° C. of the lubricating base oil may be 10 mm ² / s or more, 20 mm ² / s or more, or 30 mm ² / s or more. The kinematic viscosity at 40 ° C. of the lubricating base oil may be 150 mm ² / s or less, 100 mm ² / s or less, or 50 mm ² / s or less. The viscosity index of the lubricating base oil may be 80 or higher or 100 or higher. The kinematic viscosity and the viscosity index in the present invention mean a kinematic viscosity and a viscosity index measured according to JIS K2283, respectively.

The sulfur content of the lubricating base oil may be 10000 ppm by mass or less, 100 ppm by mass or less, or 1 ppm by mass or less. The sulfur content in the present invention is measured according to ASTM D4951 “Standard Test Method for Determining of Additive Elements in Lubricating Oils by Inductively Coupled APS”.

The content of the lubricating base oil may be, for example, 50% by mass or more, 70% by mass or more, or 90% by mass or more based on the total amount of the lubricating oil composition.

The hydraulic fluid composition contains an antioxidant containing a phenolic antioxidant. As a phenolic antioxidant, the compound represented by following formula (1) is mentioned, for example.

In the formula (1), R ¹ and R ² may be the same or different and each represents a linear or branched alkyl group having 1 to 4 carbon atoms, and R ³ represents a hydrogen atom, 1 carbon atom 4 to 4 linear or branched alkyl groups, a group represented by the following formula (2), or a group represented by the following formula (3).

In the formula (2), R ⁴ represents an alkylene group having 1 to 6 carbon atoms, and R ⁵ represents an alkyl group or alkenyl group having 1 to 24 carbon atoms.

　式（３）中、Ｒ^６は炭素数１～６のアルキレン基を示し、Ｒ^７は炭素数１～４のアルキル基を示し、Ｒ^８は水素原子又は炭素数１～４のアルキル基を示し、ｐは０又は１を示す。

In formula (3), R ⁶ represents an alkylene group having 1 to 6 carbon atoms, R ⁷ represents an alkyl group having 1 to 4 carbon atoms, and R ⁸ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. , P represents 0 or 1.

Specifically, R ¹ may be a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, etc. From an excellent viewpoint, it may be a tert-butyl group. R ² may be a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, etc., from the viewpoint of excellent thermal and oxidation stability. , A methyl group or a tert-butyl group.

When R ² is an alkyl group having 1 to 4 carbon atoms, R ³ may be a linear or branched alkyl group having 1 to 4 carbon atoms. R ³ may be, for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, etc., from the viewpoint of excellent oxidation stability. May be a methyl group or an ethyl group.

When R ¹ and R ² are linear or branched alkyl groups having 1 to 4 carbon atoms, the compound represented by the formula (1) is, for example, 2,6-di-tert-butyl-p-cresol ( DBPC), 2,6-di-tert-butyl-4-ethylphenol, 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-p-cresol (DBPC) It may be.

The phenolic antioxidant may be one of the above phenolic antioxidants or a mixture of two or more.

The content of the phenolic antioxidant may be 0.01% by mass or more, 0.1% by mass or more, or 0.3% by mass or more based on the total amount of the hydraulic fluid composition. The content of the phenolic antioxidant may be 2.0% by mass or less, 1.5% by mass or less, or 1.0% by mass or less based on the total amount of the hydraulic fluid composition.

The antioxidant may further contain an antioxidant other than the phenolic antioxidant. Examples of the antioxidant other than the phenol-based antioxidant include amine-based antioxidants and zinc-based antioxidants.

Examples of the amine antioxidant include (p, p ′)-alkylated diphenylamine represented by the following formula (A), alkylated phenyl-α-naphthylamine represented by the following formula (B), and the like. . One of these amine-based antioxidants may be used alone, or two or more thereof may be used in combination at any ratio.

In the formula (A), R ^A1 and R ^A2 each independently represents an alkyl group having 1 to 20 carbon atoms. The alkyl group as R ^A1 and R ^A2 may have 3 to 12 or 4 to 8 carbon atoms. R ^A1 and R ^A2 may be the same as or different from each other.

In formula (B), R ^B1 represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. The alkyl group as R ^B1 may have 6 to 20 or 8 to 18 carbon atoms.

The content of the amine-based antioxidant may be, for example, 0.01 to 2.0% by mass based on the total amount of the hydraulic fluid composition.

Examples of the zinc-based antioxidant include zinc dialkyldithiophosphate (ZnDTP). Zinc dialkyldithiophosphate (ZnDTP) is a component that can act as a zinc-based antiwear agent. The content of the zinc-based antioxidant is 5% by mass or less, 1% by mass or less, 0.5% by mass or less, 0.1% by mass or less based on the total amount of the hydraulic fluid composition from the viewpoint of reducing the amount of sludge. Or 0.01% by mass or less. It is preferable that the antioxidant does not contain a zinc-based antioxidant from the viewpoint of further reducing the amount of sludge.

The hydraulic fluid composition contains an organic molybdenum compound and a lubricating oil additive containing at least one selected from the group consisting of a sulfur compound containing sulfur as a constituent element and not containing molybdenum and phosphorus. The lubricating oil additive may contain both an organomolybdenum compound and a sulfur compound. That is, the hydraulic fluid composition may contain a lubricating oil additive that includes both an organic molybdenum compound and a sulfur compound. When the lubricating oil additive contains both the organic molybdenum compound and the sulfur compound, the generation of the lower carboxylic acid tends to be further suppressed.

Examples of the organic molybdenum compound include an organic molybdenum compound containing sulfur as a constituent element (a sulfur-containing organic molybdenum compound) and an organic molybdenum compound not containing sulfur as a constituent element.

The organic molybdenum compound containing sulfur as a constituent element is, for example, molybdenum dithiocarbamate (MoDTC), molybdenum dithiophosphate, or the like, and may be molybdenum dithiocarbamate (MoDTC).

Examples of molybdenum dithiocarbamate include a compound represented by the following formula (4).

In formula (4), R ⁹ , R ¹⁰ , R ¹¹ , and R ¹² each independently represent a hydrocarbon group, and X ¹ , X ² , X ³ , and X ⁴ are each independently a sulfur atom or Represents an oxygen atom. The hydrocarbon group represented by R ⁹ , R ¹⁰ , R ¹¹ , or R ¹² is an alkyl group having 2 to 24 carbon atoms or 4 to 13 carbon atoms, or 6 to 24 carbon atoms or 10 to 15 carbon atoms. It may be an (alkyl) aryl group.

Examples of the alkyl group represented by R ⁹ , R ¹⁰ , R ¹¹ , or R ¹² include an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, and an undecyl group. , Dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group and the like. These alkyl groups may be a primary alkyl group, a secondary alkyl group, or a tertiary alkyl group, and may be linear or branched.

Examples of the (alkyl) aryl group represented by R ⁹ , R ¹⁰ , R ¹¹ , or R ¹² include a phenyl group, a tolyl group, an ethylphenyl group, a propylphenyl group, a butylphenyl group, a pentylphenyl group, a hexylphenyl group, Examples include octylphenyl group, nonylphenyl group, decylphenyl group, undecylphenyl group, dodecylphenyl group, and the like. The alkyl group in the alkylaryl group may be a primary alkyl group, a secondary alkyl group, or a tertiary alkyl group, and may be linear or branched. These alkylaryl groups include all substituted isomers in which the substitution position of the alkyl group is different from that of the aryl group.

As molybdenum dithiophosphate, the compound represented by following formula (5) is mentioned, for example.

In the formula (5), R ¹³ , R ¹⁴ , R ¹⁵ , and R ¹⁶ each independently represent a hydrocarbon group, and X ⁵ , X ⁶ , X ⁷ , and X ⁸ are each independently a sulfur atom or Represents an oxygen atom. The hydrocarbon group represented by R ¹³ , R ¹⁴ , R ¹⁵ , or R ¹⁶ is an alkyl group having 2 to 30 carbon atoms, 5 to 18 carbon atoms, or 5 to 12 carbon atoms, or 6 to 18 carbon atoms. Or an (alkyl) aryl group having 10 to 15 carbon atoms. Specific examples of the alkyl group and (alkyl) aryl group represented by R ¹³ , R ¹⁴ , R ¹⁵ , or R ¹⁶ include an alkyl group represented by R ⁹ , R ¹⁰ , R ¹¹ , or R ¹² and (alkyl ) The same as the specific examples of the aryl group.

The organic molybdenum compound that does not contain sulfur as a constituent element may be, for example, an organic molybdenum compound that contains nitrogen as a constituent element and does not contain sulfur. Examples of the organic molybdenum compound containing nitrogen as a constituent element and not containing sulfur include compounds represented by the following formula (6).

In formula (6), R ¹⁷ and R ¹⁸ each independently represent a monovalent hydrocarbon group, and the monovalent hydrocarbon group may be an alkyl group. The alkyl group represented by R ¹⁷ and R ¹⁸ may have 6 to 18 or 10 to 15 carbon atoms. The alkyl group may be linear or branched.

The content of the organic molybdenum compound may be 1 mass ppm or more, 5 mass ppm or more, or 10 mass ppm or more, 200 mass ppm or less, 100 mass in terms of molybdenum element, based on the total amount of the hydraulic fluid composition. It may be ppm or less, or 50 mass ppm or less.

The organomolybdenum compound may be one of the above organomolybdenum compounds or a mixture of two or more.

Examples of the sulfur compound containing sulfur as a constituent element and not containing molybdenum and phosphorus include sulfurized esters, sulfurized olefins, thiadiazole, dithiocarbamate not containing molybdenum as a constituent element, and the like.

Sulfurized esters are, for example, so-called sulfurized fats and oils obtained by reacting animal and vegetable fats and oils such as beef tallow, pork tallow, fish fat, rapeseed oil and soybean oil by any method, unsaturated fatty acid esters obtained by reacting unsaturated fatty acids with alcohols. What was sulfurized by arbitrary methods, and what sulfided the mixture of animal and vegetable fats and oils and unsaturated fatty acid ester by arbitrary methods are mentioned. The unsaturated fatty acid may be oleic acid, linoleic acid, or the like, or may be an unsaturated fatty acid extracted from the animal or vegetable oil. The sulfurized ester may be sulfurized methyl oleate.

The sulfurized ester may have a cross-linked structure formed by sulfur atoms. The number of sulfur atoms forming the crosslinked structure (number of crosslinking) may be 1 or more, 2 or more, or 3 or more, and may be 10 or less, 8 or less, 5 or less, 4 or less, or 3 or less. .

Examples of the sulfurized olefin include a compound represented by the following formula (7).
R ¹⁹ -S _Y -R ²⁰ (7)

In formula (7), R ¹⁹ and R ²⁰ each independently represent a monovalent hydrocarbon group, and may be an alkyl group or an aryl group. The alkyl group may be linear, branched or cyclic. The carbon number of the monovalent hydrocarbon group or alkyl group represented by R ¹⁹ and R ²⁰ may be 1-20. The number of carbon atoms of the aryl group represented by R ¹⁹ and R ²⁰ may be 6-20. Y represents an integer of 1 to 8, and may be 1 to 6 or 1 to 3.

Examples of the thiadiazole include a 1,3,4-thiadiazole compound represented by the following formula (8), a 1,2,4-thiadiazole compound represented by the following formula (9), and the following formula (10). 1,2,3-thiadiazole compounds.

In the formula, R ²¹ , R ²² , R ²³ , R ²⁴ , R ²⁵ , and R ²⁶ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, and a, b, c, d, e , And f each independently represents an integer of 0-8.

Specific examples of such thiadiazole compounds include 2,5-bis (n-hexyldithio) -1,3,4-thiadiazole, 2,5-bis (n-octyldithio) -1,3,4-thiadiazole 2,5-bis (n-nonyldithio) -1,3,4-thiadiazole, 2,5-bis (1,1,3,3-tetramethylbutyldithio) -1,3,4-thiadiazole, 3, 5-bis (n-hexyldithio) -1,2,4-thiadiazole, 3,5-bis (n-octyldithio) -1,2,4-thiadiazole, 3,5-bis (n-nonyldithio) -1 , 2,4-thiadiazole, 3,5-bis (1,1,3,3-tetramethylbutyldithio) -1,2,4-thiadiazole, 4,5-bis (n-hexyldithio) -1,2 , 3-thiadiazole, , 5-bis (n-octyldithio) -1,2,3-thiadiazole, 4,5-bis (n-nonyldithio) -1,2,3-thiadiazole, 4,5-bis (1,1,3, 3-tetramethylbutyldithio) -1,2,3-thiadiazole.

Examples of the dithiocarbamate that does not contain molybdenum as a constituent element include 4,4-methylenebis (dibutyldithiocarbamate).

The sulfur compound may be one of the above sulfur compounds or a mixture of two or more.

The content of the sulfur compound may be 10 mass ppm or more, 50 mass ppm or more, or 100 mass ppm or more, 500 mass ppm or less, 300 mass ppm in terms of sulfur element, based on the total amount of the hydraulic fluid composition. Or 250 ppm by mass or less. The content of the sulfur compound means the content in terms of sulfur element measured by ICP elemental analysis.

The hydraulic fluid composition may further contain an ashless dispersant. When the hydraulic fluid composition contains an ashless dispersant, the amount of sludge tends to be reduced.

Examples of the ashless dispersant include nitrogen-containing compounds such as succinimide having an alkenyl group or alkyl group derived from polyolefin, benzylamine, polyamine, and Mannich base, and these nitrogen-containing compounds such as boric acid and borate. Examples thereof include boron-modified nitrogen-containing compounds (boron-based ashless dispersant) such as boron-modified succinimide modified with a boron compound. The ashless dispersant may be a succinimide having an alkenyl group or an alkyl group.

The content of the ashless dispersant may be 0.01% by mass or more, 0.1% by mass or more, or 0.2% by mass or more based on the total amount of the hydraulic fluid composition, and may be 5% by mass or less. It may be less than or equal to 2% by weight.

The hydraulic fluid composition may further contain a metallic detergent. When the hydraulic fluid composition contains a metal detergent, the generation of lower carboxylic acid tends to be further suppressed. Moreover, the hydraulic fluid composition may contain a metallic detergent together with the above ashless dispersant. When the hydraulic fluid composition contains a metal detergent together with the above-described ashless dispersant, the amount of sludge tends to be further reduced while the generation of lower carboxylic acid is further suppressed.

Examples of the metal detergent include neutral salts such as sulfonates, phenates, and salicylates of alkali metals or alkaline earth metals, and neutral salts such as alkali metal or alkaline earth metal base (water of alkali metal or alkaline earth metal). A basic salt or neutral salt obtained by heating an oxide, oxide, etc.) in the presence of water, and alkali metal or alkaline earth metal water in the presence of carbon dioxide gas or boric acid or borate. The overbased salt obtained by making it react with bases, such as an oxide, is mentioned. From the viewpoint of suppressing evaporation of the lower carboxylic acid by neutralizing the lower carboxylic acid, the metal detergent is a basic salt or an overbased salt such as an alkali metal or alkaline earth metal sulfonate, phenate or salicylate. It may be. Examples of the alkali metal include sodium and potassium. Examples of the alkaline earth metal include magnesium, calcium, and barium. The alkali metal or alkaline earth metal may be magnesium or calcium, and may be calcium.

The content of the metal detergent is 10 mass ppm or more, 50 mass ppm or more, or 100 mass ppm or more in terms of metal element (alkali metal element or alkaline earth metal element) based on the total amount of the hydraulic fluid composition. It may be 1000 mass ppm or less, 800 mass ppm or less, or 600 mass ppm or less. “Content of metal detergent” means content in terms of metal element measured by ICP elemental analysis.

The hydraulic fluid composition may further contain an extreme pressure agent (sulfur-phosphorus extreme pressure agent) containing sulfur and phosphorus as constituent atoms and not containing molybdenum and zinc. The sulfur-phosphorus extreme pressure agent may be an extreme pressure agent containing sulfur and phosphorus as constituent atoms and no metal. The sulfur-phosphorus extreme pressure agent may be used together with the above-described ashless dispersant and metal detergent. Use of a sulfur-phosphorus extreme pressure agent together with an ashless dispersant and a metal detergent tends to improve the seizure resistance of the hydraulic fluid composition. Examples of sulfur-phosphorus extreme pressure agents include thiophosphites (thiophosphites), dithiophosphites (dithiophosphites), trithiophosphites (trithiophosphites), and thiophosphoric acid. Examples include esters (thiophosphates), dithiophosphates (dithiophosphates), trithiophosphates (trithiophosphates), amine salts thereof, derivatives thereof, and the like. Examples of such commercially available sulfur-phosphorus extreme pressure agents include IRGALUBE (registered trademark) 353 (manufactured by BASF).

The content of the sulfur-phosphorus extreme pressure agent may be, for example, 0.001 to 1% by mass based on the total amount of the hydraulic fluid composition. The content of the sulfur-phosphorus extreme pressure agent is 0.005% by mass or more, 0.01% by mass or more, 0.03% by mass or more, 0.05% by mass or more, or from the viewpoint of seizure resistance. It may be 08% by mass or more, 0.3% by mass or less, 0.2% by mass or less, or 0.15% by mass or less.

The hydraulic fluid composition may further contain an extreme pressure agent containing phosphorus as a constituent atom and not containing molybdenum, zinc, and sulfur (hereinafter also simply referred to as “phosphorus extreme pressure agent”). The phosphorus-based extreme pressure agent may be an extreme pressure agent containing phosphorus as a constituent atom and not containing metal and sulfur. Examples of phosphorus extreme pressure agents include phosphites (phosphites), phosphate esters (neutral phosphate esters (phosphates), acidic phosphate esters, etc.), amine salts thereof, derivatives thereof, etc. Is mentioned. The content of the phosphorus extreme pressure agent may be, for example, 0.01 to 5% by mass based on the total amount of the hydraulic fluid composition.

The hydraulic fluid composition may further contain a metal deactivator other than the above thiadiazole. Examples of such metal deactivators include benzotriazole and imidazole compounds. The benzotriazole-based metal deactivator may be, for example, N, N-bis (2-ethylhexyl)-(4 or 5) -methyl-1H-benzotriazole-1-methylamine. The content of the metal deactivator may be, for example, 0.001 to 1% by mass based on the total amount of the hydraulic fluid composition.

The hydraulic fluid composition can further contain any commonly used additive depending on the purpose. Examples of such additives include pour point depressants, rust inhibitors, viscosity index improvers, antifoaming agents, demulsifiers, and oil agents. These additives may be used alone or in a mixture of two or more. When these additives are used, the respective contents may be 0.01 to 20% by mass based on the total amount of the hydraulic fluid composition.

The kinematic viscosity at 40 ° C. of the hydraulic fluid composition may be 20 mm ² / s or more, 30 mm ² / s or more, 40 mm ² / s or more, or 45 mm ² / s or more from the viewpoint of durability of the hydraulic system. . The kinematic viscosity at 40 ° C. of the hydraulic fluid composition may be 80 mm ² / s or less, 70 mm ² / s or less, 60 mm ² / s or less, or 50 mm ² / s or less from the viewpoint of reducing friction.

Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to the examples.

In Examples and Comparative Examples, using the base oils and additives shown below, the compositions shown in Table 1, Table 2, Table 3, and Table 4 ("mass%" based on the total amount of the hydraulic fluid composition) ) Was prepared.

＜金属不活性化剤＞
　Ｆ１：Ｎ，Ｎ－ビス（２－エチルヘキシル）－（４又は５）－メチル－１Ｈ－ベンゾトリアゾール－１－メチルアミン（ＩＲＧＡＭＥＴ（登録商標）３９、ＢＡＳＦ社製）
＜無灰分散剤＞
　Ｇ１：コハク酸イミド（Ｈｉｔｅｃ６３８、アフトンケミカルジャパン社製）
＜金属系清浄剤＞
　Ｈ１：過塩基性カルシウムフェネート（カルシウム含有量：５．５質量％）（ＯＬＯＡ　２１８ＡＪ、シェブロンオロナイト社製）
　Ｈ２：中性カルシウムスルホネート（カルシウム含有量：２．４質量％）（ＯＬＯＡ　２４６Ｂ、シェブロンオロナイト社製） (Base oil)
Base oil: highly refined base oil (total aromatic content: 0.3 mass%, sulfur content: 0 mass ppm, 40 ° C. kinematic viscosity: 36 mm ² / s, viscosity index: 129)
(Additive)
<Antioxidant>
A1: 2,6-di-tert-butyl-p-cresol (H-BHT, manufactured by Honshu Chemical Industry Co., Ltd.)
A2: Monobutylphenyl monooctylphenylamine (IRGANOX (registered trademark) L57, manufactured by BASF)
<Organic molybdenum compounds>
B1: Molybdenum dithiocarbamate (molybdenum content: 10% by mass) (Sakura Lube 515, manufactured by ADEKA Corporation)
B2: Molybdenum dithiophosphate (Molybdenum content: 9.7% by mass) (Sakura Lube 300, manufactured by ADEKA Corporation)
<Sulfur compounds>
C1: Sulfurized methyl oleate (sulfur atom cross-linking number = 1 to 3, sulfur content: 11% by mass) (DAILUBE GS-230S, manufactured by DIC Corporation)
C2: Methyl sulfide oleate (sulfur atom cross-linking number = 4 to 7, sulfur content: 21% by mass) (DAILUBE GS-235, manufactured by DIC Corporation)
<Phosphorus extreme pressure agent>
D1: tricresyl phosphate (TCP, manufactured by Daihachi Chemical Industry Co., Ltd.)
<Sulfur-phosphorus extreme pressure agent>
E1: Dithiophosphate represented by the following formula (IRGALUBE (registered trademark) 353, manufactured by BASF)

<Metal deactivator>
F1: N, N-bis (2-ethylhexyl)-(4 or 5) -methyl-1H-benzotriazole-1-methylamine (IRGAMET (registered trademark) 39, manufactured by BASF)
<Ashless dispersant>
G1: Succinimide (Hitec638, manufactured by Afton Chemical Japan)
<Metal-based detergent>
H1: Overbased calcium phenate (calcium content: 5.5% by mass) (OLOA 218AJ, manufactured by Chevron Oronite)
H2: neutral calcium sulfonate (calcium content: 2.4% by mass) (OLOA 246B, manufactured by Chevron Oronite)

In Tables 1 to 4, “Mo element equivalent value” means the content of B1 and B2 in terms of molybdenum element, and “S element equivalent value” means the content of C1 and C2 in terms of sulfur element. "Ca element equivalent value" means the content of H1 and H2 in terms of calcium element. The units of “Mo element equivalent value”, “S element equivalent value”, and “Ca element equivalent value” are all “mass ppm”.

(Measurement of lower carboxylic acid concentration)
The hydraulic fluid compositions of Examples 1 to 12 and Comparative Examples 1 to 4 were subjected to a high pressure piston pump test in accordance with JCMAS P045 of the Japan Construction Machinery Construction Association Standard. Specifically, using a hydraulic circuit (hydraulic device) equipped with a slanted shaft type piston pump, the hydraulic fluid composition 13L, the pump pressure 35 MPa, the pump rotation speed 1,500 min ⁻¹ , and the tank oil temperature 80 ° C. is 200. A time cycling test was performed. Thereafter, the concentration of lower carboxylic acid (mass ppm) in the air layer in the oil tank was measured according to No. Measurements were made using 81 detector tubes. The results are shown in Tables 1 to 4.

(Measurement of impurities)
The hydraulic fluid compositions of Examples 1 to 12 were subjected to a high pressure piston pump test in the same manner as the measurement of the lower carboxylic acid concentration, and then the amount of impurities (mg) in 100 mL of the hydraulic fluid composition was measured. The results are shown in Table 1, Table 3, and Table 4.

(Evaluation of SRV seizure)
For each of the hydraulic fluid compositions of Examples 6 to 12, the seizure load (N) was measured in accordance with ASTM D 7421. The seizure load was a load (N) at the time when seizure occurred and the friction coefficient increased greatly under the friction conditions of a temperature of 120 ° C., a frequency of 50 Hz, and an amplitude of 2.0 mm. In this evaluation, the larger the load value, the better the seizure resistance. The results are shown in Tables 3 and 4.

The hydraulic fluid compositions of Examples 1 to 5 had a lower carboxylic acid concentration than the hydraulic fluid compositions of Comparative Examples 1 to 4. From these results, it was confirmed that the hydraulic fluid composition of the present invention can suppress the generation of lower carboxylic acid. It was also found that the hydraulic fluid compositions of the present invention containing the ashless dispersants of Examples 6 and 7 were excellent in terms of reducing the amount of sludge. Further, the hydraulic fluid composition of the present invention containing the ashless dispersant and the metallic detergent of Examples 11 and 12 was found to be extremely excellent in terms of generation of lower carboxylic acid and reduction in sludge amount. did. It was found that the hydraulic fluid composition of the present invention of Example 12 was also excellent in terms of seizure resistance.

DESCRIPTION OF SYMBOLS 1 ... Hydraulic device, 2 ... Oil storage part, 3 ... Pressure feeding part, 5 ... Control part, 6 ... Conversion part.

Claims (16)

An oil reservoir in which a hydraulic fluid composition is stored;
A pumping unit for pumping the hydraulic fluid composition;
A control unit for controlling the hydraulic pressure, the direction of flow, or the flow rate of the pumped hydraulic fluid composition;
A converter that converts the hydraulic pressure of the controlled hydraulic fluid composition into mechanical power,
The hydraulic fluid composition is selected from the group consisting of a lubricating base oil, an antioxidant containing a phenolic antioxidant, an organic molybdenum compound, and a sulfur compound containing sulfur as a constituent element and not containing molybdenum and phosphorus. And a lubricating oil additive comprising at least one kind. The hydraulic device according to claim 1, wherein the content of the organic molybdenum compound is 50 mass ppm or less in terms of molybdenum element, based on the total amount of the hydraulic fluid composition. The hydraulic apparatus according to claim 1 or 2, wherein the organic molybdenum compound is at least one selected from the group consisting of molybdenum dithiocarbamate and molybdenum dithiophosphate. The hydraulic apparatus according to any one of claims 1 to 3, wherein the sulfur compound is at least one selected from the group consisting of sulfurized esters and sulfurized olefins. The hydraulic device according to any one of claims 1 to 4, wherein the lubricating oil additive includes both the organic molybdenum compound and the sulfur compound. The hydraulic apparatus according to any one of claims 1 to 5, wherein the hydraulic fluid composition further contains an ashless dispersant. The hydraulic apparatus according to any one of claims 1 to 6, wherein the hydraulic fluid composition further contains a metallic detergent. The hydraulic apparatus according to any one of claims 1 to 7, wherein the hydraulic fluid composition further contains an extreme pressure agent containing sulfur and phosphorus as constituent atoms and not containing molybdenum and zinc. Lubricating base oil,
Antioxidants including phenolic antioxidants;
A hydraulic fluid composition comprising an organic molybdenum compound and a lubricating oil additive containing at least one selected from the group consisting of sulfur compounds containing sulfur as a constituent element and not containing molybdenum and phosphorus. The hydraulic fluid composition according to claim 9, wherein the content of the organic molybdenum compound is 50 mass ppm or less in terms of molybdenum element, based on the total amount of the hydraulic fluid composition. The hydraulic fluid composition according to claim 9 or 10, wherein the organic molybdenum compound is at least one selected from the group consisting of molybdenum dithiocarbamate and molybdenum dithiophosphate. The hydraulic fluid composition according to any one of claims 9 to 11, wherein the sulfur compound is at least one selected from the group consisting of sulfurized esters and sulfurized olefins. The hydraulic fluid composition according to any one of claims 9 to 12, wherein the lubricating oil additive contains both the organic molybdenum compound and the sulfur compound. The hydraulic fluid composition according to any one of claims 9 to 13, further comprising an ashless dispersant. The hydraulic fluid composition according to any one of claims 9 to 14, further comprising a metal-based detergent. The hydraulic fluid composition according to any one of claims 9 to 15, further comprising an extreme pressure agent containing sulfur and phosphorus as constituent atoms and not containing molybdenum and zinc.

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