Hydraulic pressure actuating oil composition

Abstract

To provide the hydraulic pressure actuating oil composition that has excellent wear resistance and sludge generation suppressing effect even when used under a high pressure condition, and has also excellent brake performance and clutch performance.SOLUTION: The hydraulic oil composition comprises a base oil (A), an antioxidant (B) containing an amine antioxidant (B1) and a phenolic antioxidant (B2), and a succinimide compound (C), wherein the hydraulic oil composition satisfies a following requirement (I) and is used for hydraulic equipment having an operating pressure of 30 MPa or more, and the hydraulic equipment has at least one of a wet brake and a wet clutch, and is selected from construction machines, general industrial machines, and generators. The requirement (I) is a coefficient of static friction (μs) after 1000 cycles of 0.100 to 0.162 which is measured according to a test of No. 2 of SAE described in JCMAS P.047: 2004.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to hydraulic fluid compositions. [Background technology]

[0002] Hydraulic equipment installed in construction machinery such as hydraulic excavators, cranes, wheel loaders, and bulldozers is required to operate under high pressure, high temperature, high speed, and heavy load. For this reason, hydraulic oil compositions used in hydraulic equipment for construction machines are required to have wear resistance and oxidation stability that do not impair the performance of the hydraulic equipment even when used for long periods of time under high pressure, high temperature, high speed, and high load conditions. In particular, hydraulic oil compositions used in hydraulic equipment with operating pressures of 30 MPa or more are prone to early deterioration in oxidation stability and lubricating performance, and are prone to problems such as sludge generation and operational malfunctions.

[0003] For example, Patent Document 1 discloses a hydraulic oil composition for use in hydraulic equipment such as construction machinery with an operating pressure of 30 MPa or more, the hydraulic oil composition comprising a polyolefin having a specified kinetic viscosity, an amine-based antioxidant, a phenol-based antioxidant, and a phosphoric acid ester in specified ratios. Patent Document 1 discloses that the hydraulic oil composition has excellent oxidation stability and lubricating performance under high pressure, effectively prevents early deterioration and sludge generation that accompany high pressure, and can be used for a long period of time. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5503066 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, for example, hydraulic equipment mounted on construction machinery may be equipped with wet brakes and wet clutches used in hydraulic motors for traveling and hydraulic motors for turning, etc. Generally, the hydraulic oil used for the hydraulic equipment is also used for lubrication of these. Therefore, hydraulic oils used in hydraulic equipment equipped with wet brakes and wet clutches are required to have not only the above-mentioned performance as hydraulic oils, but also the lubricating performance for the wet brakes and wet clutches. In other words, hydraulic oils used in construction machinery equipped with wet brakes or wet clutches are required to have a reduced coefficient of friction in order to ensure smooth movement of hydraulic cylinders, etc., at start-up and immediately before stopping. On the other hand, the hydraulic oil is also required to have a suitably high coefficient of friction so as not to impair the braking and clutch performance of the wet brakes and wet clutches. Incidentally, in Patent Document 1, no consideration is given to the braking performance or clutch performance.

[0006] An object of the present invention is to provide a hydraulic oil composition which is excellent in wear resistance and sludge generation inhibition effect even when used under high pressure conditions, and which also has excellent brake and clutch performance. [Means for solving the problem]

[0007] The present inventors have investigated whether the static friction coefficient (μ s The present inventors have found that a hydraulic oil composition in which the above-mentioned viscosity is adjusted so that the viscosity of the hydraulic fluid falls within a specified range can solve the above problems, and have completed the present invention.

[0008] That is, the present invention provides the following [1]. [1] A composition comprising a base oil (A), an antioxidant (B) containing an amine-based antioxidant (B1) and a phenol-based antioxidant (B2), and a succinimide-based compound (C), The following requirement (I) is met, A hydraulic oil composition for use in hydraulic equipment having at least one of a wet brake and a wet clutch, and having an operating pressure of 30 MPa or more, selected from construction machinery, general industrial machinery, and generators. Requirement (I): The static friction coefficient (μ s ) is 0.100 to 0.162. Effect of the Invention

[0009] The hydraulic oil composition of the present invention is excellent in wear resistance and sludge generation inhibition effect even when used under high pressure conditions, and also has excellent braking performance and clutch performance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hydraulic Oil Composition The hydraulic oil composition of the present invention contains a base oil (A), an antioxidant (B) containing an amine-based antioxidant (B1) and a phenol-based antioxidant (B2), and a succinimide-based compound (C). The hydraulic oil composition of one embodiment of the present invention preferably contains a phosphorus-based anti-wear agent (D), and may contain other additives that do not fall under the categories of components (B) to (D) as long as the effects of the present invention are not impaired.

[0011] In the hydraulic oil composition of one embodiment of the present invention, the total content of components (A), (B), and (C) is, based on the total amount (100 mass%) of the hydraulic oil composition, preferably 60 mass% or more, more preferably 65 mass% or more, even more preferably 70 mass% or more, and still more preferably 75 mass% or more, and is usually 100 mass% or less, preferably 99.0 mass% or less, and more preferably 98.0 mass% or less.

[0012] In the hydraulic oil composition of one embodiment of the present invention, the total content of components (A), (B), (C), and (D) is, based on the total amount (100 mass%) of the hydraulic oil composition, preferably 60 mass% or more, more preferably 65 mass% or more, more preferably 70 mass% or more, even more preferably 75 mass% or more, and still more preferably 80 mass% or more, and is usually 100 mass% or less, preferably 99.5 mass% or less, and more preferably 99.0 mass% or less.

[0013] The hydraulic oil composition of the present invention is for use in hydraulic equipment having at least one of a wet brake and a wet clutch, selected from construction machinery, general industrial machinery, and generators, and having an operating pressure of 30 MPa or more, and satisfies the following requirement (I). Requirement (I): The static friction coefficient (μ s ) is 0.100 to 0.162.

[0014] As described above, hydraulic oil compositions used in hydraulic equipment equipped with wet brakes and wet clutches are required to have the performance required for hydraulic oils as well as the lubricating performance for the wet brakes and wet clutches in construction machinery and the like. In other words, requirement (I) is a provision for making a hydraulic oil composition that not only satisfies the performance required of a hydraulic oil, but also has excellent braking performance and clutch performance when used with wet brakes and wet clutches in construction machinery and the like. The static friction coefficient (μ s ) is less than 0.100, the brake performance and clutch performance, particularly in construction machinery, will be poor, and there is concern about a deterioration in responsiveness when stopping. On the other hand, the static friction coefficient (μ s ) exceeds 0.162, there is concern that the braking performance of construction machinery, etc. may deteriorate, which may lead to early wear of wet clutches.

[0015] The static friction coefficient (μ sFrom the viewpoint of improving the braking performance and clutch performance, the refractive index is preferably 0.105 or more, more preferably 0.110 or more, and even more preferably 0.115 or more, and from the viewpoint of improving the braking performance and preventing early wear, the refractive index is preferably 0.158 or less, more preferably 0.156 or less, and even more preferably 0.153 or less.

[0016] The hydraulic oil composition of the present invention contains a succinimide compound (C) together with an antioxidant (B) containing an amine-based antioxidant (B1) and a phenol-based antioxidant (B2), and further, by adjusting the type and content of component (C), the static friction coefficient (μ s ) has been adjusted to satisfy the above requirement (I). In addition, the static friction coefficient (μ s ) value also varies depending on the type and content of base oil (A) and other additives. In other words, the above requirement (I) satisfied by the hydraulic oil composition of the present invention can be said to be a regulation for the type and content of each component contained in the hydraulic oil composition. The specific method for preparing a hydraulic oil composition that satisfies the above requirement (I) is as described below for each component.

[0017] <Base oil (A)> The base oil (A) contained in the hydraulic oil composition of the present invention may be a mineral oil, a synthetic oil, or a mixed oil of two or more types selected from mineral oils and synthetic oils.

[0018] Examples of mineral oils include atmospheric residual oils obtained by atmospheric distillation of crude oils such as paraffinic crude oil, intermediate base crude oil, and naphthenic crude oil; distillate oils obtained by vacuum distillation of these atmospheric residual oils; mineral oils obtained by subjecting the distillate oils to one or more refining processes such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrorefining; and mineral oils obtained by isomerizing wax produced by the Fischer-Tropsch process or the like (GTL wax (Gas To Liquids WAX)). These mineral oils may be used alone or in combination of two or more kinds.

[0019] Among these, the mineral oil used in one embodiment of the present invention preferably includes mineral oils classified as Group 2 or Group 3 in the American Petroleum Institute (API) base oil category, and mineral oils obtained by isomerizing GTL wax.

[0020] The paraffin content (%C P ) is preferably 60 or more, more preferably 65 or more, even more preferably 70 or more, and is usually 95 or less. The naphthene content of the mineral oil (%C N ) is preferably 40 or less, more preferably 35 or less, even more preferably 30 or less, even more preferably 20 or less, still more preferably 10 or less, and is usually 5 or more. Aromatic content of the mineral oil (%C A ) is preferably less than 1.0, more preferably less than 0.5, even more preferably less than 0.1, and still more preferably less than 0.01. The paraffin content of mineral oil (%C P ), naphthene content (%C N ), and aromatic content (%C A The values ​​of ) refer to the proportions (percentages) of paraffins, naphthenes, and aromatics as measured by ASTM D-3238 ring analysis (ndM method).

[0021] Examples of synthetic oils include poly-α-olefins such as α-olefin homopolymers or α-olefin copolymers (e.g., α-olefin copolymers having 8 to 14 carbon atoms, such as ethylene-α-olefin copolymers); isoparaffin; various esters such as polyol esters and dibasic acid esters; various ethers such as polyphenyl ether; polyalkylene glycols; alkylbenzenes; and alkylnaphthalenes. Among these, the synthetic oil used in one embodiment of the present invention preferably contains one or more synthetic oils selected from poly-α-olefins, various esters, and polyalkylene glycols.

[0022] The kinematic viscosity of the base oil (A) at 40° C. is preferably 10 to 150 mm 2 / s, more preferably 12 to 120 mm 2 / s, more preferably 15 to 100 mm 2 / s, and even more preferably 20 to 80 mm 2 / s.

[0023] The viscosity index of the base oil (A) is preferably 80 or more, more preferably 90 or more, even more preferably 100 or more, and even more preferably 110 or more.

[0024] In this specification, the terms "kinematic viscosity" and "viscosity index" refer to values ​​measured in accordance with JIS K 2283. In addition, when the base oil (A) is a mixed oil consisting of two or more kinds of mineral oils, the mixed oil preferably has a kinematic viscosity and a viscosity index within the above range. Furthermore, the weighted average value calculated from the kinematic viscosity or viscosity index of each mineral oil constituting the mixed oil and the content ratio of each mineral oil can be regarded as the above-mentioned "value of the kinematic viscosity and viscosity index of the mixed oil".

[0025] In the hydraulic oil composition of one embodiment of the present invention, the content of base oil (A) is, based on the total amount (100 mass%) of the hydraulic oil composition, preferably 55 mass% or more, more preferably 60 mass% or more, even more preferably 65 mass% or more, still more preferably 70 mass% or more, particularly preferably 75 mass% or more, and is preferably 99.0 mass% or less, more preferably 98.5 mass% or less, and even more preferably 98.0 mass% or less.

[0026] <Antioxidant (B)> The antioxidant (B) contained in the hydraulic oil composition of the present invention includes an amine-based antioxidant (B1) and a phenol-based antioxidant (B2). By using the amine-based antioxidant (B1) and the phenol-based antioxidant (B2) in combination as the antioxidant (B), a hydraulic oil composition having a high sludge generation suppression effect when used in hydraulic equipment with a working pressure of 30 MPa or more can be obtained. In addition, by combining with component (C), the static friction coefficient (μ s ) can be easily adjusted to the range specified by requirement (I) above.

[0027] The amine-based antioxidant (B1) is preferably an aromatic amine compound, and more preferably at least one selected from diphenylamine compounds and naphthylamine compounds.

[0028] Examples of the diphenylamine compounds include monoalkyldiphenylamine compounds having one alkyl group having 1 to 30 carbon atoms (preferably 4 to 30, more preferably 8 to 30), such as monooctyldiphenylamine and monononyldiphenylamine; 4,4'-dibutyldiphenylamine, 4,4'-dipentyldiphenylamine, 4,4'-dihexyldiphenylamine, 4,4'-diheptyldiphenylamine, 4,4'-dioctyldiphenylamine, and 4,4'-dinonyldiphenylamine. dialkyldiphenylamine compounds having two alkyl groups having 1 to 30 carbon atoms (preferably 4 to 30, more preferably 8 to 30), such as tetrabutyldiphenylamine, tetrahexyldiphenylamine, tetraoctyldiphenylamine, tetranonyldiphenylamine, etc.; polyalkyldiphenylamine compounds having three or more alkyl groups having 1 to 30 carbon atoms (preferably 4 to 30, more preferably 8 to 30), such as tetrabutyldiphenylamine, tetrahexyldiphenylamine, tetraoctyldiphenylamine, tetranonyldiphenylamine, etc.; 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, etc.

[0029] Examples of naphthylamine compounds include phenyl-1-naphthylamine, butylphenyl-1-naphthylamine, pentylphenyl-1-naphthylamine, hexylphenyl-1-naphthylamine, heptylphenyl-1-naphthylamine, octylphenyl-1-naphthylamine, nonylphenyl-1-naphthylamine, decylphenyl-1-naphthylamine, and dodecylphenyl-1-naphthylamine.

[0030] Examples of the phenol-based antioxidant (B2) include monophenol-based antioxidants such as 2,6-di-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, isooctyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate; diphenol-based antioxidants such as 4,4'-methylenebis(2,6-di-t-butylphenol) and 2,2'-methylenebis(4-ethyl-6-t-butylphenol); hindered phenol-based antioxidants; and the like.

[0031] In one embodiment of the present invention, a hydraulic oil composition which has a high effect of suppressing sludge generation when used in hydraulic equipment having an operating pressure of 30 MPa or more and which satisfies the above-mentioned requirement (I) is provided, so that the content ratio of component (B1) to component (B2) [(B1) / (B2)], in mass ratio, is preferably 1 / 6 or more and less than 1 / 2, more preferably 1 / 5 or more and 1 / 2.3 or less, and even more preferably 1 / 4 or more and 1 / 2.5 or less.

[0032] From the above viewpoints, the content of component (B1) in the hydraulic oil composition of one embodiment of the present invention is, based on the total amount (100 mass%) of the hydraulic oil composition, preferably 0.01 to 1.0 mass%, more preferably 0.05 to 0.85 mass%, even more preferably 0.10 to 0.60 mass%, and still more preferably 0.19 to 0.45 mass%.

[0033] From the above viewpoints, the content of component (B2) in the hydraulic oil composition of one embodiment of the present invention is preferably 0.025 to 6.0 mass%, more preferably 0.10 to 5.0 mass%, even more preferably 0.20 to 4.0 mass%, and still more preferably 0.40 to 2.0 mass%, based on the total amount (100 mass%) of the hydraulic oil composition.

[0034] The antioxidant (B) used in one embodiment of the present invention may contain antioxidants other than the components (B1) and (B2). From the above viewpoint, however, it is preferable that the content of such antioxidants is as small as possible. Specifically, the total content of components (B1) and (B2) is preferably 70 to 100 mass%, more preferably 80 to 100 mass%, even more preferably 90 to 100 mass%, and still more preferably 95 to 100 mass%, based on the total amount (100 mass%) of component (B) contained in the hydraulic oil composition.

[0035] From the above viewpoints, the content of component (B) in the hydraulic oil composition of one embodiment of the present invention is, based on the total amount (100 mass%) of the hydraulic oil composition, preferably 0.035 to 7.0 mass%, more preferably 0.15 to 6.0 mass%, even more preferably 0.30 to 5.0 mass%, and still more preferably 0.59 to 3.0 mass%.

[0036] <Succinimide compounds (C)> The hydraulic oil composition of the present invention contains a succinimide compound (C). The hydraulic oil composition of the present invention is adjusted to satisfy the above requirement (I) by containing a succinimide compound (C) together with an antioxidant (B) containing an amine-based antioxidant (B1) and a phenol-based antioxidant (B2).

[0037] The succinimide compound (C) used in one embodiment of the present invention is preferably one or more selected from the alkenyl succinimide (C1) and the boronated alkenyl succinimide (C2), and more preferably contains at least the alkenyl succinimide (C1).

[0038] The alkenyl succinimide (C1) may be an alkenyl succinic acid monoimide represented by the following general formula (c-1) or an alkenyl succinic acid bisimide represented by the following general formula (c-2).

[0039] [ka]

[0040] In the above general formulas (c-1) and (c-2), R A , R A1 and R A2 are each independently an alkenyl group having a weight average molecular weight (Mw) of 500 to 3,000 (preferably 700 to 3,000, more preferably 1,000 to 2,500). R B , R B1 and R B2 each independently represents an alkylene group having 2 to 5 carbon atoms. R C is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or -(AO) n A is a group represented by —H (wherein A is an alkylene group having 2 to 4 carbon atoms, and n is an integer of 1 to 10). x1 is an integer of 1 to 10, preferably an integer of 2 to 5, and more preferably 3 or 4. x2 is an integer of 0 to 10, preferably an integer of 1 to 4, and more preferably 2 or 3.

[0041] R A , R A1 and R A2 Examples of the alkenyl group that can be selected for include a polybutenyl group, a polyisobutenyl group, an ethylene-propylene copolymer, and the like. Among these, a polybutenyl group or a polyisobutenyl group is preferred.

[0042] The boronated alkenyl succinimide (C2) may be a boron-modified alkenyl succinimide represented by the above general formula (c-1) or (c-2). The ratio [B / N] of boron atoms to nitrogen atoms constituting the boronated alkenyl succinimide (C2) is preferably 0.01 to 0.6, more preferably 0.05 to 0.5, and even more preferably 0.1 to 0.4.

[0043] In the hydraulic oil composition of one embodiment of the present invention, from the viewpoint of providing a hydraulic oil composition that satisfies the above-mentioned requirement (I), the content of component (C) relative to 100 parts by mass of the total amount of components (B1) and (B2) is preferably 1.0 to 20.0 parts by mass, more preferably 5.0 to 18.0 parts by mass, and even more preferably 12.0 to 17.0 parts by mass.

[0044] In the hydraulic oil composition of one embodiment of the present invention, from the viewpoint of providing a hydraulic oil composition that satisfies the above-mentioned requirement (I), the content of component (C) is preferably 0.01 to 1.0 mass%, more preferably 0.07 to 0.90 mass%, even more preferably 0.09 to 0.80 mass%, and still more preferably 0.10 to 0.60 mass%, based on the total amount (100 mass%) of the hydraulic oil composition.

[0045] From the above viewpoints, the content of component (C) calculated as nitrogen atoms is preferably 1 to 120 ppm by mass, more preferably 5 to 100 ppm by mass, even more preferably 7 to 90 ppm by mass, and even more preferably 10 to 70 ppm by mass, based on the total amount (100% by mass) of the hydraulic oil composition. In this specification, the nitrogen atom content refers to a value measured in accordance with JIS K2609.

[0046] When the hydraulic oil composition according to one embodiment of the present invention contains a boronated alkenyl succinimide (C2) as component (C), the content of component (C) calculated as boron atoms is preferably 1 to 300 ppm by mass, more preferably 3 to 200 ppm by mass, and even more preferably 5 to 100 ppm by mass, based on the total amount (100 mass%) of the hydraulic oil composition. In this specification, the content of boron atoms means a value measured in accordance with JPI-5S-38-03.

[0047] The hydraulic oil composition of one embodiment of the present invention may further contain other ashless dispersants that do not fall under component (C), provided the effects of the present invention are not impaired. Examples of such other ashless dispersants include benzylamines, boron-containing benzylamines, succinic acid esters, fatty acids, and mono- or di-carboxylic acid amides such as succinic acid.

[0048] However, in the hydraulic oil composition of one embodiment of the present invention, from the viewpoint of obtaining a hydraulic oil composition that satisfies the above-mentioned requirement (I), it is preferable that the content of other ashless dispersants that do not fall under component (C) is as small as possible. Specifically, the content of the other ashless dispersant is preferably less than 10 parts by mass, more preferably less than 5 parts by mass, even more preferably less than 1 part by mass, and even more preferably less than 0.01 parts by mass, based on 100 parts by mass of the total amount of component (C) contained in the hydraulic oil composition.

[0049] <Phosphorus-based anti-wear agent (D)> From the viewpoint of further improving wear resistance, the hydraulic oil composition of one embodiment of the present invention preferably further contains a phosphorus-based wear inhibitor (D). The phosphorus-based antiwear agent (D) is preferably at least one selected from phosphoric acid esters and amine salts of phosphoric acid esters. Examples of the phosphoric acid ester include neutral phosphoric acid esters such as aryl phosphate, alkyl phosphate, alkenyl phosphate, and alkylaryl phosphate; acidic phosphoric acid esters such as monoaryl acid phosphate, diaryl acid phosphate, monoalkyl acid phosphate, dialkyl acid phosphate, monoalkenyl acid phosphate, and dialkenyl acid phosphate; phosphite esters such as aryl hydrogen phosphite, alkyl hydrogen phosphite, aryl phosphite, alkyl phosphite, alkenyl phosphite, and aryl alkyl phosphite; and acidic phosphite esters such as monoalkyl acid phosphite, dialkyl acid phosphite, monoalkenyl acid phosphite, and dialkenyl acid phosphite. These phosphate esters may be used alone or in combination of two or more kinds.

[0050] The amine constituting the amine salt of the phosphoric acid ester is preferably a compound represented by the following general formula (di): The amine may be used alone or in combination of two or more kinds. [ka]

[0051] In the general formula (di), q represents an integer of 1 to 3, and is preferably 1. R d each independently represents an alkyl group having 6 to 18 carbon atoms, an alkenyl group having 6 to 18 carbon atoms, an aryl group having 6 to 18 ring carbon atoms, an arylalkyl group having 7 to 18 carbon atoms, or a hydroxyalkyl group having 6 to 18 carbon atoms, and preferably an alkyl group having 6 to 18 carbon atoms. In addition, R d If there are multiple R d may be the same as each other or different from each other.

[0052] In the hydraulic oil composition of one embodiment of the present invention, from the viewpoint of further improving the wear resistance, load bearing property, and scoring resistance, component (D) preferably contains a compound (D1) selected from acidic phosphate esters (D11) and amine salts of acidic phosphate esters (D12), and more preferably contains a neutral phosphate ester (D2) together with compound (D1).

[0053] The acidic phosphoric acid ester (D11) is preferably a compound represented by the following general formula (d1-1) or a compound represented by the following general formula (d1-2). [ka]

[0054] In the general formulae (d1-1) and (d1-2), R a and R b are each independently an alkyl group having 1 to 12 carbon atoms (3 to 10, more preferably 3 to 8, and even more preferably 3 to 6). R a and R b may be the same or different from each other.

[0055] As the amine salt of an acidic phosphoric acid ester (D12), an amine salt of a compound represented by the above-mentioned general formula (d1-1) or an amine salt of a compound represented by the above-mentioned general formula (d1-2) is preferable. The amine constituting component (D12) is preferably a compound represented by the above general formula (di).

[0056] As the neutral phosphate ester (D2), a compound represented by the following general formula (d2-1) is preferable, and a compound represented by the following general formula (d2-2) is more preferable. [ka]

[0057] In the general formula (d2-1), R 1 ~R 3are each independently an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 18 ring carbon atoms substituted with an alkyl group having 1 to 12 carbon atoms.

[0058] In addition, in the general formula (d2-2), R 11 ~R 13 each independently represents an alkyl group having 1 to 12 carbon atoms. p1 to p3 each independently represents an integer of 1 to 5, preferably an integer of 1 or 2, and more preferably 1.

[0059] From the viewpoint of further improving the wear resistance, load bearing property, and scoring resistance, the compound (D1) is preferably an amine salt of an acidic phosphoric acid ester (D12). For this reason, it is more preferable to contain a neutral phosphate ester (D2) together with the component (D12).

[0060] In the hydraulic oil composition of one embodiment of the present invention, when component (D) contains both component (D1) and component (D2), the content ratio of component (D1) to component (D2) [(D1) / (D2)] is, in terms of mass ratio, 0.001 to 2.000, more preferably 0.005 to 1.000, even more preferably 0.007 to 0.500, and still more preferably 0.010 to 0.100, from the viewpoint of further improving wear resistance, load bearing property, and scoring resistance.

[0061] In the hydraulic oil composition of one embodiment of the present invention, the total content of components (D1) and (D2) is preferably 70 to 100 mass%, more preferably 80 to 100 mass%, even more preferably 90 to 100 mass%, and still more preferably 95 to 100 mass%, based on the total amount (100 mass%) of component (D) contained in the hydraulic oil composition.

[0062] In the hydraulic oil composition of one embodiment of the present invention, the content of component (D) is preferably 0.1 to 2.0 mass%, more preferably 0.2 to 1.2 mass%, even more preferably 0.3 to 1.0 mass%, and still more preferably 0.5 to 0.9 mass%, based on the total amount (100 mass%) of the hydraulic oil composition.

[0063] <Other additives> The hydraulic oil composition of one embodiment of the present invention may contain other hydraulic oil additives other than the above components (B) to (D) to the extent that the effects of the present invention are not impaired. Other hydraulic fluid additives include, for example, viscosity index improvers, pour point depressants, extreme pressure agents, rust inhibitors, metal deactivators, demulsifiers, antifoam agents, and the like. These hydraulic oil additives may be used alone or in combination of two or more kinds.

[0064] The content of each of these hydraulic oil additives can be appropriately adjusted within a range that does not impair the effects of the present invention, but is usually 0.001 to 15 mass%, preferably 0.005 to 10 mass%, and more preferably 0.01 to 8 mass%, based on the total amount (100 mass%) of the hydraulic oil composition.

[0065] In this specification, additives such as viscosity index improvers and antifoaming agents may be blended with other components in the form of a solution in which they are diluted and dissolved in a part of the above-mentioned base oil (A), taking into consideration handling properties and solubility in the base oil (A). In such a case, in this specification, the above-mentioned contents of additives such as antifoaming agents and viscosity index improvers refer to the contents calculated as active ingredients (resin content) excluding diluent oil.

[0066] In the hydraulic oil composition of one embodiment of the present invention, the content of phosphorus atoms is preferably 100 to 1000 ppm by mass, more preferably 250 to 900 ppm by mass, even more preferably 350 to 800 ppm by mass, and still more preferably 450 to 750 ppm by mass, based on the total amount (100 mass%) of the hydraulic oil composition. In this specification, the phosphorus atom content means a value measured in accordance with JPI-5S-38-03.

[0067] Furthermore, in the hydraulic oil composition of one embodiment of the present invention, from the viewpoint of providing a hydraulic oil composition that has a high effect of suppressing sludge generation when used in hydraulic equipment having an operating pressure of 30 MPa or more, the content of zinc dithiophosphate (ZnDTP) is preferably as small as possible, and it is more preferable that the composition is substantially free of zinc dithiophosphate (ZnDTP). Specifically, in the hydraulic oil composition of one embodiment of the present invention, the content of zinc atoms is preferably less than 100 ppm by mass, more preferably less than 10 ppm by mass, even more preferably less than 5 ppm by mass, and even more preferably less than 1 ppm by mass, based on the total amount (100 mass%) of the hydraulic oil composition. In this specification, the zinc atom content refers to a value measured in accordance with JPI-5S-38-03.

[0068] From the same viewpoint as above, the content of the sulfur atom-containing compound is also preferably as small as possible, and it is more preferable that the composition does not substantially contain any sulfur atom-containing compound. Specifically, in the hydraulic oil composition of one embodiment of the present invention, the content of sulfur atoms is preferably less than 200 ppm by mass, more preferably less than 150 ppm by mass, and even more preferably less than 100 ppm by mass, based on the total amount (100 mass%) of the hydraulic oil composition. In this specification, the content of sulfur atoms means a value measured in accordance with JIS K2541-6:2013.

[0069] [Various properties of hydraulic oil composition] The kinematic viscosity at 40°C of the hydraulic oil composition of one embodiment of the present invention is preferably 10 to 100 mm 2 / s, more preferably 13 to 75 mm 2 / s, more preferably 25 to 55 mm 2 / s.

[0070] The viscosity index of the hydraulic oil composition of one embodiment of the present invention is preferably 100 or more, more preferably 110 or more, and even more preferably 120 or more.

[0071] For the hydraulic oil composition of one embodiment of the present invention, the amount of sludge generated when a high-pressure piston pump test is carried out for 500 hours in accordance with JCMAS P045 under the conditions described in the Examples described later is preferably less than 5.0 mg / 100 ml, more preferably less than 3.0 mg / 100 ml, even more preferably less than 2.0 mg / 100 ml, still more preferably less than 1.0 mg / 100 ml, and particularly preferably less than 0.5 mg / 100 ml. In this specification, details of the high-pressure piston pump test and the method for measuring the amount of sludge are as described in the Examples section below.

[0072] With respect to the hydraulic oil composition of one embodiment of the present invention, the amount of wear of the vanes and the cam ring when a base pump (manufactured by Vickers, product name "V-104C") is operated for 100 hours, as measured in accordance with ASTM D2882 under the conditions described in the Examples described later, is preferably less than 30 mg, more preferably less than 25 mg, even more preferably less than 22 mg, and still more preferably less than 10 mg.

[0073] The hydraulic oil composition of one embodiment of the present invention has a friction coefficient measured in accordance with JASO-M314-88 of preferably 0.160 or less, more preferably 0.150 or less, even more preferably 0.140 or less, and still more preferably 0.120 or less. The friction coefficient is a value measured based on the method described in the examples.

[0074] The hydraulic oil composition of one embodiment of the present invention preferably has a weld load (WL) measured in accordance with ASTM D2783 of 1300N or more, more preferably 1500N or more, and even more preferably 1800N or more. The welding load (WL) refers to a value measured based on the method described in the Examples.

[0075] [Uses of hydraulic oil composition] The hydraulic oil composition of the present invention is excellent in wear resistance and sludge generation inhibition effect even when used under high pressure conditions, and also has excellent brake performance and clutch performance in construction machines and the like. Therefore, the hydraulic oil composition of the present invention can be suitably used in hydraulic equipment having at least one of a wet brake and a wet clutch, and having an operating pressure of 30 MPa or more, selected from construction machinery, general industrial machinery, and generators.

[0076] Examples of the above-mentioned construction machinery include cranes such as mobile cranes, fixed cranes, and derricks; excavating machinery such as hydraulic excavators, mini excavators, and wheeled hydraulic excavators; leveling machinery such as bulldozers; loading machinery such as wheel loaders; transport machinery such as off-road transport vehicles; compaction machinery such as vibrating rollers; demolition machinery such as breakers; foundation work machinery such as pile drivers and earth augers; concrete and asphalt machinery such as concrete pump trucks; aerial work vehicles, paving machinery, shields, tunneling machines, snow removal machines, etc. Examples of the general industrial machinery include vehicles, machine tools, gear devices, transport devices, air conditioning equipment, and mining equipment.

[0077] That is, the present invention can also provide a hydraulic device as shown in (1) below, and a method for using the hydraulic oil composition as shown in (2) below. (1) A hydraulic device using a hydraulic oil composition comprising a base oil (A), an antioxidant (B) containing an amine-based antioxidant (B1) and a phenol-based antioxidant (B2), and a succinimide-based compound (C), and satisfying the requirement (I), A hydraulic device having at least one of a wet brake and a wet clutch, selected from construction machinery, general industrial machinery, and generators, and having an operating pressure of 30 MPa or more. (2) A method for using a hydraulic oil composition comprising a base oil (A), an antioxidant (B) containing an amine-based antioxidant (B1) and a phenol-based antioxidant (B2), and a hydraulic equipment having an operating pressure of 30 MPa or more, the hydraulic equipment being selected from construction machinery, general industrial machinery, and generators and having at least one of a wet brake and a wet clutch. The preferred embodiments of the hydraulic oil composition defined in (1) and (2) above are as described above. EXAMPLES

[0078] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. The various properties of the components used in the examples and comparative examples and the hydraulic oil compositions obtained were measured according to the methods described below.

[0079] <Kinematic viscosity, viscosity index> Measurements and calculations were made in accordance with JIS K 2283:2000. <Content of phosphorus atoms and zinc atoms> Measurements were performed in accordance with JPI-5S-38-03. <Sulfur atom content> Measurements were performed in accordance with JIS K2541-6:2013. <Nitrogen atom content> Measurements were performed in accordance with JIS K2609.

[0080] Examples 1-2, Comparative Examples 1-2 The base oils and various additives shown below were added in the amounts shown in Table 1 and thoroughly mixed to prepare hydraulic oil compositions. Details of the mineral oils and various additives used in the examples and comparative examples are as follows.

[0081] <Base oil> "100N mineral oil": Mineral oil classified as Group III in the API category, kinematic viscosity at 40°C = 20.44 mm 2 / s, viscosity index=122, %C P =73.5, %C N =26.5, %C A =0.0. "150N mineral oil": Mineral oil classified as Group II in the API category, kinematic viscosity at 40°C = 30.60 mm 2 / s, viscosity index=104, %C P =67.1, %C N =32.9, %C A=0.0. "500N mineral oil": Mineral oil classified as Group II in the API category, 40℃ kinematic viscosity = 90.51mm 2 / s, viscosity index=107, %C P =72.0, %C N =28.0, %C A =0.0

[0082] <Antioxidants> - "Amine antioxidants": alkylated diphenylamines. · "Phenolic antioxidant": 2,6-di-t-butyl-4-methylphenol. <Ashless friction modifier> "Succinimide": Polybutenyl succinic acid bisimide having a polybutenyl group with a number average molecular weight (Mn) of 1000, nitrogen atom content = 1.15 mass%. <Anti-wear agent> "Amine salt of acidic phosphate ester" · “Neutral phosphate ester”: tricresyl phosphate. "ZnDTP": Zinc dithiophosphate <Other additives> · “Rust inhibitor”: Sorbitan monooleate. · "Metal deactivators": Benzotriazoles. - Viscosity index improver: Polymethacrylate with a weight-average molecular weight of 37,000. - Pour point depressant: Polymethacrylate with a weight average molecular weight of 69,000. - "Antifoaming agent": Silicone-based antifoaming agent.

[0083] For the hydraulic oil compositions prepared in the Examples and Comparative Examples, the 40° C. kinematic viscosity and viscosity index, as well as the contents of phosphorus atoms, sulfur atoms, and zinc atoms were measured. The results are shown in Table 1. The following measurements were carried out using the hydraulic oil compositions prepared in the Examples and Comparative Examples as sample oils. The results of these measurements are also shown in Table 1.

[0084] (1) Static friction coefficient (μ s ) Based on the SAENo.2 test described in JCMAS P 047:2004, the static friction coefficient (μ s ) was measured.

[0085] (2) High-pressure piston pump test In accordance with JCMAS P045, the sample oil was introduced into the hydraulic circuit of a high-pressure piston pump test device (pump: BOSCH-REXROTH A2F10), and a high-pressure piston pump test was performed for 500 hours under the conditions of a pump pressure of 35.0 MPa, a sample oil temperature of 80°C, and an air blowing rate of 1.0 L / h. Then, in accordance with JIS B 9931, the amount of sludge (unit: mg / 100 ml) generated in the sample oil after the test was measured.

[0086] (3) Pump wear test Using a vane pump (manufactured by Vickers, product name "V-104C"), the wear amount (unit: mg) of the vane and cam ring was measured after 100 hours of operation in accordance with ASTM D2882 under the conditions of pump pressure 13.8 MPa, oil temperature 66°C, rotation speed 1200 rpm, sample oil amount 60 L, and flow rate 25 L / min.

[0087] (4) Sota-type pendulum test The friction coefficient was measured at an oil temperature of 60°C using a Soda pendulum tester (type II) in accordance with the "Soda pendulum test" specified in JASO-M314-88.

[0088] (5) Shell 4-ball EP test In accordance with ASTM D2783, the weld load (WL) was measured using a four-ball tester at a rotation speed of 1,800 rpm and a temperature of 25° C. The larger the weld load (WL) value, the more excellent the load resistance.

[0089] (6) FZG scoring test In accordance with ASTM D5182-97, an A-type gear was used, and the load was increased stepwise in accordance with the regulations under the conditions of a sample oil temperature of 90°C, a rotation speed of 1450 rpm, and an operating time of 15 minutes, and the load stage at which scoring occurred was determined. The higher the value of the stage, the better the resistance to scoring.

[0090] [Table 1]

[0091] The hydraulic oil compositions prepared in Examples 1 and 2 had a static friction coefficient (μ s ) is in a moderate range, it is believed to have excellent brake and clutch performance. In addition, even when used under high pressure conditions of 30 MPa, it has excellent sludge generation suppression effect and good wear resistance. On the other hand, the hydraulic oil compositions prepared in Comparative Examples 1 and 2 had a low static friction coefficient (μ s ) is high, there is concern that this could lead to a deterioration in braking performance and early wear and tear on the wet clutch.

Claims

1. The present invention relates to a composition comprising a base oil (A), an antioxidant (B) containing an amine-based antioxidant (B1) and a phenol-based antioxidant (B2), and a succinimide-based compound (C), The following requirement (I) is satisfied: A hydraulic oil composition for use in hydraulic equipment having at least one of a wet brake and a wet clutch, and having an operating pressure of 30 MPa or more, selected from construction machinery, general industrial machinery, and generators. Requirement (I): The static friction coefficient (μ ｓ ) is 0.100 to 0.

162.

2. 2. The hydraulic oil composition according to claim 1, wherein the content of zinc atoms is less than 100 ppm by mass, based on the total amount of the hydraulic oil composition.

3. 3. The hydraulic oil composition according to claim 1, wherein the content of component (C) is 1.0 to 20.0 parts by mass based on 100 parts by mass of the total amount of components (B1) and (B2).

4. The hydraulic oil composition according to any one of claims 1 to 3, wherein the content ratio of component (B1) to component (B2) [(B1) / (B2)], in terms of mass ratio, is 1 / 6 or more and less than 1 / 2.

5. The hydraulic oil composition according to any one of claims 1 to 4, wherein the content of component (B1) is 0.01 to 1.0 mass% based on the total amount of the hydraulic oil composition.

6. The hydraulic oil composition according to any one of claims 1 to 5, wherein the content of component (B2) is 0.025 to 6.0 mass% based on the total amount of the hydraulic oil composition.

7. The hydraulic oil composition according to any one of claims 1 to 6, wherein the content of component (C) is 0.01 to 1.0 mass% based on the total amount of the hydraulic oil composition.

8. The hydraulic oil composition according to any one of claims 1 to 7, further comprising a phosphorus-based antiwear agent (D).

9. 9. The hydraulic oil composition according to claim 8, wherein component (D) contains a compound (D1) selected from acid phosphate esters (D11) and amine salts of acid phosphate esters (D12).

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