Hydraulic operating oil

Abstract

To provide a hydraulic operating oil with excellent functionality.SOLUTION: A hydraulic operating oil in an aspect of the present invention comprises one or more base oils selected from the group consisting of Group 2 base oils, Group 3 base oils, and GTL base oils, 2,6-di-tert-butylphenol, tris(2,4-di-tert-butylphenyl) phosphite and an amine antioxidant.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] Hydraulic equipment is used in various fields such as the construction and civil engineering fields because it can produce a large output even though it is a simple and small device.

[0003] Hydraulic equipment generally includes hydraulic actuators such as hydraulic motors and hydraulic cylinders, and the hydraulic actuators such as the hydraulic motor and hydraulic cylinders are operated by hydraulic oil pressurized by driving a hydraulic pump using an engine or the like.

[0004] As a hydraulic oil for use in such hydraulic equipment, Patent Document 1 proposes a hydraulic oil containing a base oil, an amine-based antioxidant, a phenol-based antioxidant, a phosphoric acid ester, and a fatty acid amide or a polyhydric alcohol ester. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-111277 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the lubricating oil disclosed in Patent Document 1 sometimes does not have sufficient performance as a hydraulic oil (for example, thermal stability, oxidation stability, sludge inhibition, etc.).

[0007] Therefore, an object of the present invention is to provide a hydraulic oil having excellent performance. [Means for solving the problem]

[0008] The present inventors have conducted extensive research and found that the above problems can be solved by a composition containing a specific component.

[0009] One aspect of the present invention comprises One or more base oils selected from the group consisting of Group 2 base oils, Group 3 base oils, and GTL base oils; 2,6-di-tert-butylphenol, Tris(2,4-di-tert-butylphenyl) phosphite, An amine-based antioxidant; A hydraulic fluid comprising:

[0010] The amine-based antioxidant is preferably a diphenylamine-based antioxidant. The content of the amine-based antioxidant relative to the total amount of the hydraulic oil is preferably 0.05 to 0.50% by mass. The content of the 2,6-di-tert-butylphenol relative to the total amount of the hydraulic oil is preferably 0.30 to 2.00 mass %. The content of the tris(2,4-di-tert-butylphenyl)phosphite relative to the total amount of the hydraulic oil is preferably 0.30 to 2.00 mass %. Effect of the Invention

[0011] According to the present invention, a hydraulic oil having excellent performance can be provided. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, when an upper limit value and a lower limit value are separately described, it is deemed that a numerical range combining any upper limit value and any lower limit value is substantially disclosed.

[0013] The composition, production method, applications, etc. of the composition will be specifically explained below, but the present invention is not limited thereto.

[0014] <<Composition>> The hydraulic fluid according to the present disclosure preferably comprises a base oil, 2,6-di-tert-butylphenol, tris(2,4-di-tert-butylphenyl)phosphite, and an amine antioxidant. The base oil preferably contains at least one or more base oils selected from the group consisting of Group 2 base oils, Group 3 base oils, and GTL base oils, and more preferably contains at least one or more base oils selected from the group consisting of Group 3 base oils and GTL base oils. Hydraulic fluids according to the present disclosure may also contain other components.

[0015] Each component will be described below.

[0016] <Base oil> Group 2 base oils generally have a viscosity index of 80 or greater but less than 120, a sulfur content of 0.03 mass percent or less and a saturates content of 90 volume percent or greater. Group 2 base oils include paraffinic mineral oils produced by applying an appropriate combination of refining procedures such as hydrocracking and dewaxing to the lubricating oil fraction obtained by atmospheric distillation of crude oil.

[0017] Group 3 base oils generally have a viscosity index of 120 or greater, a sulfur content of 0.03 mass percent or less and a saturates content of 90 volume percent or more. Group 3 base oils include paraffinic mineral oils produced by advanced hydrorefining of lubricating oil fractions obtained by atmospheric distillation of crude oil, base oils refined by the ISODEWAX process, which converts and dewaxes the wax produced in the wax and dewaxing process into isoparaffins, and base oils refined by the MobilWAX isomerization process.

[0018] GTL base oil is a base oil synthesized using the Fischer-Tropsch process, a technology for converting natural gas into liquid fuel, and has extremely low sulfur and aromatic contents and an extremely high proportion of paraffins.

[0019] GTL (Gas to Liquid) base oils generally fall under Group 2 base oils and Group 3 base oils. In this disclosure, a base oil that is both Group 3 base oil and GTL base oil is treated as a component that falls under both, and a base oil that is both Group 2 base oil and GTL base oil is treated as a component that falls under both.

[0020] The 100°C kinematic viscosity of the base oil is not particularly limited, but may be, for example, 2.0 to 15.0 mm 2 / s, or 2.5 to 13.0 mm 2 / s is preferred.

[0021] The kinematic viscosity of the base oil at 40°C is not particularly limited, but may be, for example, 22.0 to 100 mm 2 / s, 30.0~100mm 2 / s, or 32.0 to 68.0 mm 2 / s is preferred.

[0022] The total amount of Group 2 base oil, Group 3 base oil, and GTL base oil is preferably at least 50 mass%, at least 60 mass%, at least 70 mass%, at least 80 mass%, at least 90 mass%, or at least 95 mass%, when the total amount of the hydraulic oil is 100 mass%.

[0023] In addition, the total amount of Group 2 base oil, Group 3 base oil, and GTL base oil (preferably the total amount of Group 3 base oil and GTL base oil, more preferably the amount of GTL base oil) is preferably 50 mass% or more, 60 mass% or more, 70 mass% or more, 80 mass% or more, 90 mass% or more, 95 mass% or more, or 99 mass% or more, when the total amount of base oils in the hydraulic oil is 100 mass%.

[0024] <2,6-di-tert-butylphenol> 2,6-Di-tert-butylphenol is a compound having the following structure:

[0025] [ka]

[0026] The content of 2,6-di-tert-butylphenol in the hydraulic oil is preferably 0.10 mass% or more, 0.20 mass% or more, or 0.30 mass% or more, and is preferably 5.00 mass% or less, 4.00 mass% or less, or 2.00 mass% or less, when the total amount of the hydraulic oil is 100 mass%.

[0027] <Tris(2,4-di-tert-butylphenyl) phosphite> Tris(2,4-di-tert-butylphenyl) phosphite is the compound having the following structure:

[0028] [ka]

[0029] The content of tris(2,4-di-tert-butylphenyl)phosphite in the hydraulic oil is preferably 0.10 mass% or more, 0.20 mass% or more, or 0.30 mass% or more, and is preferably 5.00 mass% or less, 4.00 mass% or less, or 2.00 mass% or less, when the total amount of the hydraulic oil is 100 mass%.

[0030] <Amine-based antioxidants> The amine-based antioxidant is not particularly limited, but examples thereof include aromatic amine-based antioxidants and hindered amine-based antioxidants.

[0031] The amine-based antioxidant is preferably an aromatic amine-based antioxidant.

[0032] Examples of the aromatic amine antioxidants include diphenylamine antioxidants (such as alkyldiphenylamines) and naphthylamine antioxidants (such as alkylnaphthylamines, phenyl-α-naphthylamines, phenyl-β-naphthylamines, and alkylphenyl-α-naphthylamines).

[0033] When the aromatic amine antioxidant has an alkyl group, the number of carbon atoms of the alkyl group can be 1 or more, 2 or more, or 4 or more, and can be 30 or less, 20 or less, 15 or less, or 10 or less. When the aromatic amine antioxidant has an alkyl group, the number of alkyl groups in one molecule is not particularly limited, and may be 1, 2, or 3 or more. When the aromatic amine antioxidant has multiple alkyl groups in one molecule, the number of carbon atoms of each alkyl group may be the same or different.

[0034] The aromatic amine-based antioxidant is preferably a diphenylamine-based antioxidant.

[0035] Examples of the hindered amine antioxidant include tetrakis(2,2,6,6-tetramethyl-4-piperidyl)1,2,3,4-butanetetracarboxylate, (2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, and decanedioic acid bis(2,2,6,6-tetramethyl-1(octyloxy)-4-piperidinyl ester).

[0036] It was found that by using one or more base oils selected from the group consisting of Group 2 base oils, Group 3 base oils, and GTL base oils as the base oil, and by using 2,6-di-tert-butylphenol, tris(2,4-di-tert-butylphenyl) phosphite, and an amine-based antioxidant in combination, the thermal stability / oxidation stability is improved and the generation of sludge is suppressed, making it suitable for use as a hydraulic oil.

[0037] The content of the amine-based antioxidant in the hydraulic oil is preferably 0.01 mass % or more, 0.02 mass % or more, or 0.05 mass % or more, and is preferably 1.00 mass % or less, 0.50 mass % or less, 0.20 mass % or less, or 0.10 mass % or less, when the total amount of the hydraulic oil is 100 mass %.

[0038] The ratio of the content of the amine antioxidant to the content of 2,6-di-tert-butylphenol in the hydraulic oil [content of the amine antioxidant / content of 2,6-di-tert-butylphenol] is preferably 0.010 or more, 0.015 or more, 0.020 or more, or 0.025 or more, and is preferably 1.000 or less, 0.800 or less, 0.600 or less, or 0.500 or less. By setting such a ratio, it is possible to improve the thermal stability / oxidation stability and suppress the generation of sludge in a well-balanced manner.

[0039] The ratio of the content of the amine-based antioxidant to the content of tris(2,4-di-tert-butylphenyl) phosphite in the hydraulic oil [content of amine-based antioxidant / content of tris(2,4-di-tert-butylphenyl) phosphite] is preferably 0.010 or more, 0.015 or more, 0.020 or more, or 0.025 or more, and is preferably 3.000 or less, 2.000 or less, 1.500 or less, 1.200 or less, or 1.000 or less. It is presumed that such a ratio allows the phosphorus-based antioxidant to adequately exert the effect of extending the life of the phenol-based and amine-based antioxidants, and allows for a well-balanced improvement in thermal stability / oxidative stability and the inhibition of sludge generation.

[0040] <Other ingredients> The hydraulic oil according to the present disclosure may contain other components, such as known additives, for example, viscosity index improvers, rust inhibitors, copper deactivators, antiwear agents, extreme pressure agents, dispersants, metal detergents, friction modifiers, corrosion inhibitors, demulsifiers, pour point depressants, and antifoaming agents.

[0041] The content of other components in the hydraulic oil is not particularly limited and may be appropriately adjusted depending on the physical properties required for the hydraulic oil, and may be, for example, 0.10 mass% or more, 0.50 mass% or more, or 1.00 mass% or more, and 20.00 mass% or less, 10.00 mass% or less, or 5.00 mass% or less, when the total amount of the hydraulic oil is 100 mass%. The hydraulic oil need not contain other components.

[0042] In addition, when the hydraulic oil contains other antioxidants as components other than 2,6-di-tert-butylphenol, tris(2,4-di-tert-butylphenyl) phosphite, and the amine-based antioxidant, the content of the other antioxidants is preferably 0.10 mass% or less, 0.05 mass% or less, 0.02 mass% or less, 0.01 mass% or less, or 0.00 mass% when the total amount of the hydraulic oil is 100 mass%.

[0043] In other words, the ratio of the content of antioxidants other than amine-based antioxidants to the content of amine-based antioxidants in the hydraulic oil [content of antioxidants other than amine-based antioxidants / content of amine-based antioxidants] is preferably 0.50 or less, 0.20 or less, 0.10 or less, 0.05 or less, or 0.01 or less.

[0044] <<Manufacturing method>> The hydraulic oil according to the present disclosure can be produced according to a known method, and the components may be mixed appropriately, and the order of mixing is not particularly limited. The additives contained in the hydraulic oil according to the present disclosure may be added to the base oil as a package product in which multiple types are mixed.

[0045] <<Applications>> The hydraulic oil according to the present disclosure exhibits excellent thermal stability / oxidation stability and is less likely to produce sludge, and therefore, by applying the hydraulic oil according to the present disclosure to a hydraulic device, it is possible to improve the long-term reliability.

[0046] The hydraulic devices to which the hydraulic working fluid according to the present disclosure can be applied are not particularly limited, and examples thereof include construction machines, general industrial machines, generators, and the like.

[0047] Note that the hydraulic working fluid according to the present disclosure can also be used as a normal lubricating oil composition. In other words, the hydraulic working fluid according to the present disclosure can be applied to uses other than hydraulic working fluids (for example, machine oil, turbine oil, compressor oil, gear oil, sliding surface oil, bearing oil, calibration oil, etc.).

Examples

[0048] <<Preparation of Composition>> Each component in the ratios shown in Tables 1 and 2 was mixed with the base oil to obtain the compositions according to each example and each comparative example. The numerical values (%) shown in the table indicate the content (% by mass) of each component when the total amount of the composition is 100% by mass, and the balance is all base oil.

[0049] <Raw Materials> ·GTL base oil (GTL base oil with a kinematic viscosity at 40°C of about 44 mm 2 / s) ·Group 2 base oil (a mixed base oil of 60 parts by mass of a Group 2 base oil with a kinematic viscosity at 40°C of about 30 mm 2 / s and 40 parts by mass of a Group 2 base oil with a kinematic viscosity at 40°C of about 100 mm 2 / s) ·2,6-Di-tert-butylphenol ·Tris(2,4-di-tert-butylphenyl) phosphite ·Amine-based antioxidant (diphenylamine-based antioxidant) ·Phenolic antioxidant (manufactured by BASF Japan, IRGANOX L135, a hindered phenolic antioxidant)

[0050] <<Evaluation>> <ISOT Life Evaluation> For the compositions according to each example and each comparative example, the ISOT life was evaluated according to the evaluation method shown below. The evaluation results are shown in Tables 1 and 2.

[0051] The testing machine and testing method complied with JIS K2514. A catalyst (Cu and Fe plates) was immersed in a sample at 150°C, and the kinematic viscosity at 40°C was measured at regular intervals during the test. The time when the kinematic viscosity at 40°C increased rapidly was measured as the lifespan. When the lifespan in the ISOT lifespan evaluation is 1000 hours or more (preferably 1200 hours or more), it is judged to have very excellent stability.

[0052] <Sludge generation> The sludge generation in the composition after the above-mentioned ISOT lifespan evaluation was confirmed. In the table, the amount of sludge generated in the composition after evaluation was visually confirmed by the level of turbidity of the lubricating oil. Those with little or no turbidity were evaluated as "-", and those with a lot of turbidity after evaluation were evaluated as "much".

[0053]

Table 1

[0054]

Table 2

[0055] <RBOT test> Furthermore, based on the RBOT test method, stability evaluations from a different perspective than the ISOT lifespan evaluation were conducted for Example 1 and Comparative Examples 4 and 6. Also, in this test, Comparative Example 8 in which tris(2,4-di-tert-butylphenyl) phosphite was added to the composition of Comparative Example 6 was prepared and stability evaluation was carried out. The evaluation results are shown in Table 3. (Evaluation method) In accordance with the rotary bomb lubricating oil oxidation stability test (RBOT) specified in JIS K 2514 3.3, the oxidation lifespan at 150°C was measured. When the oxidation lifespan in the RBOT test is 800 minutes or more, it can be judged to have excellent stability.

[0056]

Table 3

[0057] These results show that a composition obtained by combining a specified base oil, 2,6-di-tert-butylphenol, tris(2,4-di-tert-butylphenyl) phosphite, and an amine-based antioxidant exhibits excellent stability (long oxidation life) even in the RBTO test.

Claims

1. One or more base oils selected from the group consisting of Group 2 base oils, Group 3 base oils, and GTL base oils; 2,6-di-tert-butylphenol, tris(2,4-di-tert-butylphenyl) phosphite, An amine-based antioxidant; Hydraulic fluid comprising:

2. 2. The hydraulic fluid of claim 1, wherein the amine-based antioxidant is a diphenylamine-based antioxidant.

3. 3. The hydraulic oil according to claim 1, wherein the content of the amine-based antioxidant is 0.05 to 0.50 mass % based on the total amount of the hydraulic oil.

4. 3. The hydraulic oil according to claim 1, wherein the content of the 2,6-di-tert-butylphenol relative to the total amount of the hydraulic oil is 0.30 to 2.00 mass %.

5. 3. The hydraulic oil according to claim 1, wherein the content of the tris(2,4-di-tert-butylphenyl)phosphite is 0.30 to 2.00 mass% based on the total amount of the hydraulic oil.

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