JP2002129181A - Hydraulic oil composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic oil composition high in sludge resistance and excellent in frictional characteristic. SOLUTION: The composition is based on one or more oils selected from the group consisting of mineral oil, fatty oil, and synthetic oil, and contains (A) 0.01-5 mass% of a phenolic oxidation inhibitor and/or an aminic oxidation inhibitor, (B) 0.01-10 mass% of a phosphorus compound and/or a sulfur compound, and (C) 0.001-5 mass% of a compound by formula (1) described below, but does not contain zinc dithiophosphate practically. The formula (1) is R1- CH2COOH [wherein, R1 is an alkyl group having 7-29 carbons, an alkenyl group having 7-29 carbons, or a group described by formula (2): R2-C6H4O- (wherein, R2 is an alkyl group having 1-20 carbons or a hydrogen)].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hydraulic fluid composition, and more particularly to a hydraulic fluid composition having good sludge resistance and excellent friction characteristics.

[0002]

2. Description of the Related Art In a hydraulic circuit, a sliding portion such as metal-metal or metal-rubber (resin) exists in a pump, a control valve, a hydraulic cylinder, and the like. The hydraulic oil used in such a hydraulic circuit is required to have good friction characteristics such as wear resistance and seizure resistance. Further, from the viewpoint of energy saving in recent years, it has been required to improve the performance of the hydraulic working oil by reducing the resistance in the sliding portion, thereby reducing the loss energy and suppressing the rise in the oil temperature. Conventionally, zinc dithiophosphate (ZnDTP) has been added to improve friction characteristics. However, ZnDTP not only has insufficient friction characteristics, but also tends to become sludge when used under severe conditions. May enter the sliding surface and increase the sliding resistance. In addition, in order to reduce the cost of maintenance of the hydraulic circuit, a hydraulic oil that can be used for a long period of time is required, and it is necessary that the hydraulic oil has good friction characteristics and that its excellent effects can be maintained for a long period of time. Have been. However, no hydraulic oil has been obtained which is excellent in both sludge resistance and friction characteristics and can maintain the excellent friction characteristics for a long period of time.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a hydraulic oil composition which has excellent sludge resistance and friction characteristics, and does not show any deterioration in friction characteristics even after long-term use.

[0004]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the object of the present invention can be effectively achieved by using a specific compound as an additive in a base oil. Is completed. That is, the hydraulic fluid composition of the present invention comprises, as a base oil, at least one selected from mineral oils, fats and oils, and (A) a phenolic antioxidant and / or an amine antioxidant. 01
-5% by mass, (B) 0.01-10% by mass of a phosphorus compound and / or a sulfur-based compound, and (C) 0.001-5% by mass of a compound represented by the following general formula (1). And a hydraulic oil composition substantially free of zinc dithiophosphate. R ¹ —CH ₂ COOH (1) (wherein, R ¹ is an alkyl group having 7 to 29 carbon atoms,
To 29-alkenyl groups or groups represented by general formula (2). R ² —C ₆ H ₄ O— (2) (wherein, R ² represents an alkyl group having 1 to 20 carbon atoms or hydrogen).

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. In the hydraulic fluid composition of the present invention, at least one selected from mineral oil, fat and oil and synthetic oil is used as a base oil. Here, as for the mineral oil, the lubricating oil fraction obtained by atmospheric distillation and vacuum distillation of the crude oil, solvent removal,
Paraffin or naphthene obtained by appropriately combining one or more purification means such as solvent extraction, hydrocracking, solvent dewaxing, contact dewaxing, hydrorefining, sulfuric acid washing, and clay treatment. Mineral oil. Examples of oils and fats include beef tallow, lard, sunflower oil, soybean oil, rapeseed oil, rice bran oil, coconut oil, palm oil, palm kernel oil, and hydrogenated products thereof.

As synthetic oils, for example, poly-α-
Olefins (ethylene-propylene copolymer, polybutene, 1-octene oligomer, 1-decene oligomer,
And hydrides thereof), alkylbenzene, alkylnaphthalene, monoester (butyl stearate,
Octyl laurate), diester (ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-2-
Ethylhexyl sepacate, etc.), polyester (Trimellitic acid ester, etc.), polyol ester (Trimethylolpropane caprylate, Trimethylolpropaneperargonate, Pentaerythritol-2-ethylhexanoate, Pentaerythritol pelargonate, etc.), polyoxyalkylene Glycols, polyphenyl ethers, dialkyl diphenyl ethers, phosphate esters (tricresyl phosphate, etc.), fluorinated compounds (perfluoropolyethers, fluorinated polyolefins, etc.), silicone oils and the like can be exemplified. As the base oil of the hydraulic fluid composition of the present invention, the above-described base oils may be used alone or in combination of two or more.

[0007] The kinematic viscosity of these base oils is not particularly limited, and is arbitrary. However, from the viewpoints of excellent friction characteristics, cooling properties (heat removal properties), and little friction loss due to stirring resistance.
Usually, the kinematic viscosity at 40 ° C. is preferably 10 to 10,
000 mm ² / s, more preferably 20 to 1,000 m
m ² / s. The viscosity index is also optional, but usually from 80 to 500, more preferably 100, from the viewpoint of suppressing oil film reduction at high temperatures.
~ 300. Further, the pour point is also arbitrary, but usually, the pour point is preferably −5 ° C. or lower, more preferably −15 ° C. or lower from the viewpoint of pump startability in winter.

[0008] (A) in the hydraulic oil composition of the present invention
The component is (A-1) a phenolic antioxidant and / or (A-2) an amine antioxidant.

As the phenolic antioxidant (A-1), any alkylphenolic compound used as an antioxidant for lubricating oils can be used, and is not particularly limited. One or more alkylphenol compounds selected from the compounds represented by the general formula (3) or (4) are preferred.

[0010]

Embedded image In the formula (3), R ⁴ represents an alkyl group having 1 to 4 carbon atoms, R ⁵ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ⁶ represents a hydrogen atom and 1 to 4 carbon atoms. An alkyl group, a group represented by the following general formula (i) or the following general formula (ii)
Represents a group represented by

[0011]

Embedded image In the formula (i), R ⁷ represents an alkylene group having 1 to 6 carbon atoms, and R ⁸ represents an alkyl group or an alkenyl group having 1 to 24 carbon atoms.

[0012]

Embedded image In the above formula (ii), R ⁹ represents an alkylene group having 1 to 6 carbon atoms, R ¹⁰ represents an alkyl group having 1 to 4 carbon atoms, and R ¹¹
Represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and n represents an integer of 0 or 1.

[0013]

Embedded image In the above formula (4), R ¹² and R ¹⁶ are each independently:
R ¹³ and R ¹⁷ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; R ¹⁴ and R ¹⁵ each independently represent a C 1 -C 4 alkyl group; ~
And Y represents an alkylene group having 1 to 18 carbon atoms or a group represented by the following general formula (iii). —R ¹⁸ —S—R ¹⁹ — (iii) In the formula (iii), R ¹⁸ and R ¹⁹ each independently represent an alkylene group having 1 to 6 carbon atoms.

In the general formula (3), R ⁴ has 1 to 1 carbon atoms.
4 represents an alkyl group. Specific examples of such an alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and an s group.
Examples thereof include an ec-butyl group and a tert-butyl group, and a tert-butyl group is preferable from the viewpoint of more excellent sludge resistance. R ⁵ is a hydrogen atom or a carbon number 1 to
4 represents an alkyl group. Specific examples of such an alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and an s group.
An ec-butyl group and a tert-butyl group are exemplified.
Among them, a hydrogen atom, a methyl group or a tert-butyl group is preferred from the viewpoint of more excellent sludge resistance.

In the general formula (3), R ⁶ is a hydrogen atom,
An alkyl group having 1 to 4 carbon atoms, a group represented by the above formula (i) or a group represented by the above formula (ii) is shown. As the alkyl group having 1 to 4 carbon atoms represented by R ⁶ , specifically, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-
Butyl group, isobutyl group, sec-butyl group, tert
-Butyl group and the like, and a methyl group or an ethyl group is preferable from the viewpoint of more excellent sludge resistance.

When R ⁶ in the general formula (3) is a group represented by the formula (i), the alkylene group having 1 to 6 carbon atoms represented by R ⁷ in the formula (i) is a straight-chain alkylene group. And may be branched, for example, methylene, methylmethylene, ethylene (dimethylene), ethylmethylene, propylene (methylethylene), trimethylene, straight or branched Butylene group, linear or branched pentylene group, linear or branched hexylene group, and the like.
As R ⁷ , among them, a compound represented by the general formula (3) can be produced in a small number of reaction steps,
More preferably, the alkylene group is a methylene group, a methylmethylene group, an ethylene group (dimethylene group) or the like.

On the other hand, carbon number 1 represented by R ⁸ in the formula (i)
The alkyl group or alkenyl group may be linear or branched, and specifically, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group , Nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, henycosyl group, docosyl group, tricosyl group, tetracosyl group, etc. Alkyl groups (these alkyl groups may be straight-chain or branched); vinyl, propenyl, isopropenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl,
Undecenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group, hexadecenyl group,
An alkenyl group such as a heptadecenyl group, an octadecenyl group, an octadecadienyl group, a nonadecenyl group, an icosenyl group, a henicocenyl group, a docosenyl group, a tricosenyl group, a tetracosenyl group (these alkenyl groups may be linear or branched; The position of the double bond is also arbitrary.)
And the like. As R ⁸ , among these, an alkyl group having 4 to 18 carbon atoms, for example, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, from the viewpoint of excellent solubility in a base oil. , Decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, alkyl group such as octadecyl group (these alkyl groups may be linear or branched), A straight-chain or branched alkyl group having 6 to 12 carbon atoms is more preferable, and a branched alkyl group having 6 to 12 carbon atoms is particularly preferable.

Among the phenol compounds represented by the general formula (3), when R ⁶ is a group represented by the formula (i), R ^{7 in the} formula (i) is a compound having 1 to 1 carbon atoms. a 2 alkylene group, more preferably those wherein R ⁸ is linear or branched alkyl group having 6 to 12 carbon atoms, R ⁷ in formula (i) an alkylene group having 1 to 2 carbon atoms , R ⁸
Is particularly preferably a branched alkyl group having 6 to 12 carbon atoms. When R ⁶ in the general formula (3) is a group represented by the formula (ii), R ⁹ in the formula (ii) represents an alkylene group having 1 to 6 carbon atoms. The alkylene group may be linear or branched, and specific examples include various alkylene groups exemplified above for R ⁷ . As R ⁹ , among these, an alkylene group having 1 to 3 carbon atoms can be produced because the compound of the general formula (3) can be produced in a small number of reaction steps and its raw material is easily available.
Specifically, for example, a methylene group, a methylmethylene group, an ethylene group (dimethylene group), an ethylmethylene group, a propylene group (methylethylene group), a trimethylene group, and the like are more preferable.

Further, R ¹⁰ in the formula (ii) has 1 to 4 carbon atoms.
Represents an alkyl group. Specifically, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group,
Examples thereof include an isobutyl group, a sec-butyl group, and a tert-butyl group.
A t-butyl group is preferred. Examples of R ¹¹ include a hydrogen atom and an alkyl group having 1 to 4 carbon atoms as described above, and a hydrogen atom, a methyl group, or a tert-butyl group is preferable from the viewpoint of excellent sludge resistance. (Ii) In the formula, n represents an integer of 0 or 1. When n is 0, a biphenyl structure in which two benzene rings are directly bonded is formed.

In the general formula (3), as described above, R ⁶
Is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, and the above formula (i)
Or a group represented by the above formula (ii), and among these, an alkyl group having 1 to 4 carbon atoms or a group represented by the above formula (ii) is preferable, and a methyl group , An ethyl group, or a group represented by the above formula (ii), wherein R ⁹ is an alkylene group having 1 to 3 carbon atoms;
More preferably, ¹⁰ is a tert-butyl group, R ¹¹ is a hydrogen atom, a methyl group or a tert-butyl group, and n is an integer of 0 or 1.

As the compound represented by the general formula (3),
As described above, various compounds are included. Among these, preferred compounds are listed as compounds in which R ⁶ is an alkyl group having 1 to 4 carbon atoms, such as 2,6-di-tert-.
Butyl-p-cresol, 2,6-di-tert-butyl-4-ethylphenol and the like; when R ⁶ is a group represented by the general formula (i), (3-methyl-5)
-Tert-butyl-4-hydroxyphenyl) acetic acid n
-Hexyl, (3-methyl-5-tert-butyl-4
-Hydroxyphenyl) isohexyl acetate, (3-methyl-5-tert-butyl-4-hydroxyphenyl)
N-heptyl acetate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) isoheptyl acetate, (3
-Methyl-5-tert-butyl-4-hydroxyphenyl) acetic acid n-octyl, (3-methyl-5-tert)
-Butyl-4-hydroxyphenyl) acetic acid isooctyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetic acid 2-ethylhexyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetic acid n -Nonyl, (3-methyl-5-tert-butyl-
4-Hydroxyphenyl) isononyl acetate, (3-methyl-5-tert-butyl-4-hydroxyphenyl)
N-decyl acetate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) isodecyl acetate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) n-undecyl acetate, (3-methyl- 5-tert
-Butyl-4-hydroxyphenyl) isoundecyl acetate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate n-dodecyl, (3-methyl-5-
tert-butyl-4-hydroxyphenyl) isododecyl acetate, (3-methyl-5-tert-butyl-4-)
N-hexyl (hydroxyphenyl) propionate, (3
Isohexyl-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl-5-
n-heptyl tert-butyl-4-hydroxyphenyl) propionate, isoheptyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) ) N-octyl propionate, (3-methyl-5-tert-butyl-4-hydroxyphenyl)
Isooctyl propionate, (3-methyl-5-ter
t-butyl-4-hydroxyphenyl) propionic acid 2
-Ethylhexyl, n-nonyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, isononyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl- N-decyl 5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl-5-tert-
Isodecyl (butyl-4-hydroxyphenyl) propionate, n-undecyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3-
Isoundecyl methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl-5
n-dodecyl tert-butyl-4-hydroxyphenyl) propionate, isododecyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3,5-di-tert-butyl-4-hydroxyphenyl) ) N-hexyl acetate, (3,5-di-tert)
-Butyl-4-hydroxyphenyl) acetic acid isohexyl, (3,5-di-tert-butyl-4-hydroxyphenyl) acetic acid n-heptyl, (3,5-di-tert)
-Butyl-4-hydroxyphenyl) acetate isoheptyl, (3,5-di-tert-butyl-4-hydroxyphenyl) acetate n-octyl, (3,5-di-tert)
-Butyl-4-hydroxyphenyl) acetic acid isooctyl, (3,5-di-tert-butyl-4-hydroxyphenyl) acetic acid 2-ethylhexyl, (3,5-di-t
n-nonyl tert-butyl-4-hydroxyphenyl) acetate, isononyl (3,5-di-tert-butyl-4-hydroxyphenyl) acetate, (3,5-di-tert)
-Butyl-4-hydroxyphenyl) n-decyl acetate;
Isodecyl (3,5-di-tert-butyl-4-hydroxyphenyl) acetate, n-undecyl (3,5-di-tert-butyl-4-hydroxyphenyl) acetate,
(3,5-di-tert-butyl-4-hydroxyphenyl) isoundecyl acetate, (3,5-di-tert-butyl)
Butyl-4-hydroxyphenyl) n-dodecyl acetate;
Isododecyl (3,5-di-tert-butyl-4-hydroxyphenyl) acetate, n-hexyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, (3,5-di-tert- Isohexyl butyl-4-hydroxyphenyl) propionate, n-heptyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, (3,5-di-tert-butyl-4-hydroxyphenyl) propion Isoheptyl acid, n-octyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, (3,5-di-
tert-butyl-4-hydroxyphenyl) isooctyl propionate, (3,5-di-tert-butyl-
2-ethylhexyl 4-hydroxyphenyl) propionate, n-nonyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, (3,5-di-
tert-butyl-4-hydroxyphenyl) isononyl propionate, (3,5-di-tert-butyl-4)
-Hydroxyphenyl) n-decyl propionate,
(3,5-di-tert-butyl-4-hydroxyphenyl) isodecyl propionate, (3,5-di-tert-butyl)
t-butyl-4-hydroxyphenyl) propionic acid n
-Undecyl, (3,5-di-tert-butyl-4-
(Hydroxyphenyl) isoundecyl propionate,
(3,5-di-tert-butyl-4-hydroxyphenyl) n-dodecyl propionate, (3,5-di-te
rt-butyl-4-hydroxyphenyl) isododecyl propionate and the like; as a compound when R ⁶ is a group represented by the formula (ii), bis (3,5-di-tert-butyl-4-hydroxyphenyl) , Bis (3,5-di-
tert-butyl-4-hydroxyphenyl) methane,
1,1-bis (3,5-di-tert-butyl-4-hydroxyphenyl) ethane, 1,2-bis (3,5-di-tert-butyl-4-hydroxyphenyl) ethane, 1,1- Bis (3,5-di-tert-butyl-4
-Hydroxyphenyl) propane, 1,2-bis (3,
5-di-tert-butyl-4-hydroxyphenyl)
Propane, 1,3-bis (3,5-di-tert-butyl-4-hydroxyphenyl) propane, 2,2-bis (3,5-di-tert-butyl-4-hydroxyphenyl) propane and the like; and These mixtures and the like can be mentioned.

On the other hand, in the above general formula (4), R ¹²
And R ¹⁶ each independently represent an alkyl group having 1 to 4 carbon atoms. Specifically, it shows 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., both of which are more excellent in sludge resistance. tert
Preferably it is a -butyl group. R ¹³ and R ¹⁷ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Examples of such an alkyl group include the groups described above. Among these, a hydrogen atom, a methyl group, or a tert-butyl group is preferably individually selected from the viewpoint of more excellent sludge resistance. In the general formula (4), the alkylene group having 1 to 6 carbon atoms represented by R ¹⁴ and R ¹⁵ may be linear or branched. Examples include the various alkylene groups described above for ⁷ . R ¹⁴ and R
^{As No. 15} , carbon compounds having 1 to 2 carbon atoms can be produced individually in that the compound represented by the general formula (4) can be produced in a small number of reaction steps and the raw materials thereof can be easily obtained.
And more specifically, for example, a methylene group, a methylmethylene group, an ethylene group (dimethylene group) and the like are more preferable.

In the general formula (4), Y represents an alkylene group having 1 to 18 carbon atoms or a group represented by the above formula (iii). Specific examples of the alkylene group having 1 to 18 carbon atoms represented by Y include methylene, methylmethylene, ethylene (dimethylene), ethylmethylene, propylene (methylethylene), trimethylene, and butylene. Group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group, decylene group, undecylene group, dodecylene group, tridecylene group, tetradecylene group, pentadecylene group, hexadecylene group, heptadecylene group, octadecylene group, etc. Linear or branched), but from the viewpoint of easy availability of raw materials, an alkylene group having 1 to 6 carbon atoms,
Specifically, for example, methylene group, methylmethylene group, ethylene group (dimethylene group), ethylmethylene group, propylene group (methylethylene group), trimethylene group, butylene group, pentylene group, hexylene group and the like (these alkylene groups are Straight-chain or branched).
C2-C6 linear alkylene such as ethylene group (dimethylene group), trimethylene group, linear butylene group (tetramethylene group), linear pentylene group (pentamethylene group), linear hexylene group (hexamethylene group) Groups are particularly preferred.

Among the alkylphenols represented by the general formula (4), particularly preferred as the compound when Y is an alkylene group having 1 to 18 carbon atoms is a compound represented by the following formula (5). .

Embedded image

Further, when Y in the general formula (4) is a group represented by the formula (iii), R in the formula (iii)
An alkylene group having 1 to 6 carbon atoms represented by ¹⁸ and R ¹⁹ is
It may be straight-chain or branched, and specifically includes, individually, various alkylene groups as described above for R ⁷ . As R ¹⁸ and R ¹⁹ , among them, raw materials for producing the compound of the general formula (4) are easily available, and therefore, each independently represents an alkylene group having 1 to 3 carbon atoms, specifically, for example, More preferably, it is a methylene group, a methylmethylene group, an ethylene group (dimethylene group), an ethylmethylene group, a propylene group (methylethylene group), a trimethylene group, or the like.

Among the alkylphenols represented by the general formula (4), when Y is a group represented by the formula (iii), a particularly preferable compound is a compound represented by the following formula (6). is there.

Embedded image As described above, in the general formula (4), Y has 1 to 1 carbon atoms.
Y represents an alkylene group represented by general formula (iii) or a group represented by general formula (iii). Y is preferably a group represented by general formula (iii) because of excellent sludge resistance.

On the other hand, as the amine antioxidant (A-2), any aromatic amine compound used as an antioxidant for lubricating oils can be used, and is not particularly limited. One or more aromatic amines selected from phenyl-α-naphthylamines represented by the following general formula (7) and p, p′-dialkyldiphenylamine represented by the following general formula (8) Are preferred.

[0028]

Embedded image In the formula (7), R ²⁰ represents a hydrogen atom or an alkyl group having 1 to 16 carbon atoms.

[0029]

Embedded image In the formula (8), R ²¹ and R ²² each independently represent an alkyl group having 1 to 16 carbon atoms.

In the above formula (7), R ²⁰ represents a hydrogen atom or a linear or branched alkyl group having 1 to 16 carbon atoms. If the carbon number of R ²⁰ exceeds 16, the proportion of the functional group in the molecule becomes small, and the sludge resistance may be reduced. Specific examples of the alkyl group for R ²⁰ include a methyl group, 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, an undecyl group, a dodecyl group, Tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, etc. (these alkyl groups may be linear or branched)
Is mentioned.

Among the compounds represented by the general formula (7), R
^{When 20} is an alkyl group, a branched alkyl group having 8 to 16 carbon atoms is preferable from the viewpoint of excellent solubility of the oxidation product of itself in the base oil, and further, an oligomer of an olefin having 3 or 4 carbon atoms is preferable. A derived C8-16 branched alkyl group is more preferred. Specific examples of the olefin having 3 or 4 carbon atoms include propylene, 1
-Butene, 2-butene and isobutylene, but propylene or isobutylene is preferred because of its excellent solubility of the oxidation product of itself in the base oil. Further, when R ²⁰ is an alkyl group, a branched octyl group derived from a dimer of isobutylene and a trimer of propylene are preferred because of the superior solubility of the oxidation product of itself in the base oil. A branched nonyl group, a branched dodecyl group derived from a trimer of isobutylene, a branched dodecyl group derived from a tetramer of propylene, or a branched pentadecyl group derived from a pentamer of propylene. More preferred is a branched octyl group derived from a dimer of isobutylene, a branched dodecyl group derived from a trimer of isobutylene, or a branched dodecyl group derived from a tetramer of propylene. As described above, R ²⁰
May be a hydrogen atom or an alkyl group,
It is preferably a hydrogen atom from the viewpoint of antioxidant ability, and is preferably an alkyl group from the viewpoint of solubility of its own oxidation product.

In the aromatic amine represented by the formula (7), R
^As the compound in which ²⁰ is an alkyl group, commercially available phenyl-α-naphthylamines may be used. Further, phenyl-α-naphthylamine and a halogenated alkyl compound having 1 to 16 carbon atoms, an olefin having 2 to 16 carbon atoms, or an olefin oligomer having 2 to 16 carbon atoms and phenyl-α-naphthylamine using a Friedel-Crafts catalyst. By reacting, it can be easily synthesized. In this case, the Friedel Crafts catalyst includes:
Specifically, for example, metal halides such as aluminum chloride, zinc chloride and iron chloride; acid catalysts such as sulfuric acid, phosphoric acid, phosphorus pentoxide, boron fluoride, acid clay, activated clay and the like can be used.

On the other hand, in the above formula (8) representing p, p'-dialkyldiphenylamine, R ²¹ and R ²² each independently represent an alkyl group having 1 to 16 carbon atoms. When one or both of R ²¹ and R ²² is a hydrogen atom, it may itself settle as sludge by oxidation, while
When the number of carbon atoms exceeds 16, the proportion of the functional group in the molecule becomes small, and the sludge resistance may be reduced. As R ²¹ and R ²² , specifically, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, undecyl, dodecyl, tridecyl Group, tetradecyl group, pentadecyl group, hexadecyl group and the like (these alkyl groups may be linear or branched). Among them, R ²¹ and R ²² each have 3 to 3 carbon atoms because of their excellent solubility of oxidation products of the base oil itself.
A branched alkyl group having 16 carbon atoms is preferable, and a branched alkyl group having 3 to 16 carbon atoms derived from an olefin having 3 or 4 carbon atoms or an oligomer thereof is more preferable. Specific examples of the olefin having 3 or 4 carbon atoms include propylene, 1-butene, 2-butene, isobutylene, and the like, and are excellent in solubility of an oxidation product of itself in a lubricating base oil. From the viewpoint, propylene or isobutylene is preferred.

Further, R ²¹ and R ²² are preferably isopropyl group derived from propylene, tert-butyl group derived from isobutylene, A branched hexyl group derived from a propylene dimer, a branched octyl group derived from an isobutylene dimer, a branched nonyl group derived from a propylene trimer, a derivative derived from an isobutylene trimer. Even more preferred are branched dodecyl groups, branched dodecyl groups derived from propylene tetramers or branched pentadecyl groups derived from propylene pentamers, and tert-butyl groups derived from isobutylene, A branched hexyl group derived from a dimer, a branched octyl group derived from a dimer of isobutylene, A branched nonyl group derived from dimer,
Most preferred is a branched dodecyl group derived from a trimer of isobutylene or a tetramer of propylene.

As the p, p'-dialkyldiphenylamine represented by the formula (8), a commercially available product may be used.
Similarly to the phenyl-α-naphthylamine represented by the formula (7), diphenylamine and a halogenated alkyl compound having 1 to 16 carbon atoms, an olefin having 2 to 16 carbon atoms, an olefin having 2 to 16 carbon atoms, or an olefin having these The compound can be easily synthesized by reacting the oligomer with diphenylamine using a Friedel-Crafts catalyst. As the Friedel-Crafts catalyst at this time, specifically, for example, metal halides and acidic catalysts listed in the synthesis of phenyl-α-naphthylamine are used.

As a matter of course, as the component (A) of the present invention, one compound selected from phenolic antioxidants and amine antioxidants may be used alone. A mixture of two or more compounds selected from the above at an arbitrary mixing ratio may be used, but a phenolic antioxidant and an amine antioxidant are used in combination because they are more excellent in sludge resistance. Is preferred.

(A) in the hydraulic oil composition of the present invention
Although the content of the component is arbitrary, the upper limit is preferably 5% by mass, more preferably 3% by mass, still more preferably 1% by mass, and most preferably 0.5% by mass, based on the total amount of the composition.
% By mass. If the content exceeds 5% by mass, no further improvement in the effect of suppressing sludge corresponding to the content is observed, and the solubility in the base oil decreases, which is not preferable. On the other hand, the lower limit of the content of the component (A) is preferably 0.01% by mass, more preferably 0.02% by mass, and still more preferably 0.05% by mass, based on the total amount of the composition.
Most preferably, it is 0.1% by mass. When the content of the component (A) is less than 0.01% by mass, the effect of adding the component is not seen, and the sludge resistance of the hydraulic oil may be deteriorated.

(B) in the hydraulic oil composition of the present invention
The component is a phosphorus compound and / or a sulfur compound. As the phosphorus compound in the present invention, specifically,
Phosphoric acid esters such as phosphoric acid monoester, phosphoric acid diester, phosphoric acid triester; phosphorous acid monoester,
Phosphites such as phosphite diester and phosphite triester; salts of these phosphites and phosphites; and mixtures thereof. The above-mentioned phosphates and phosphites are usually
A hydrocarbon group having 2 to 30, preferably 3 to 20 carbon atoms
(Monoester), two (diester) or three (triester).

As the hydrocarbon group having 2 to 30 carbon atoms, specifically, for example, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group Group, dodecyl group,
Alkyl groups such as tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group and octadecyl group (the alkyl groups may be linear or branched); butenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl Alkenyl groups such as group, nonenyl group, decenyl group, undecenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group, hexadecenyl group, heptadecenyl group and octadecenyl group (these alkenyl groups may be linear or branched; The position of the double bond is also arbitrary); cyclopentyl group,
5-7 carbon atoms such as cyclohexyl group and cycloheptyl group
A cycloalkyl group of methylcyclopentyl, dimethylcyclopentyl, methylethylcyclopentyl,
Diethylcyclopentyl group, methylcyclohexyl group,
C6-C6 such as dimethylcyclohexyl, methylethylcyclohexyl, diethylcyclohexyl, methylcycloheptyl, dimethylcycloheptyl, methylethylcycloheptyl, diethylcycloheptyl, etc.
11 alkylcycloalkyl groups (the substitution position of an alkyl group with a cycloalkyl group is also arbitrary); a phenyl group,
Aryl groups such as naphthyl group: tolyl group, xylyl group, ethylphenyl group, propylphenyl group, butylphenyl group, pentylphenyl group, hexylphenyl group, heptylphenyl group, octylphenyl group, nonylphenyl group, decylphenyl group, C7-C18 alkylaryl groups such as decylphenyl group and dodecylphenyl group (the alkyl group may be linear or branched, and the position of substitution on the aryl group is arbitrary); benzyl group, phenyl group An arylalkyl group having 7 to 12 carbon atoms such as an ethyl group, a phenylpropyl group, a phenylbutyl group, a phenylpentyl group, and a phenylhexyl group (the alkyl groups may be linear or branched); .

Specific examples of preferred compounds as component (B) include, for example, monopropyl phosphate, monobutyl phosphate, monopentyl phosphate, monohexyl phosphate, monoheptyl phosphate, and the like.
Monoalkyl phosphates such as monooctyl phosphate (the alkyl group may be linear or branched); Mono (alkyl) aryl phosphates such as monophenyl phosphate and monocresyl phosphate; dipropyl phosphate, dibutyl phosphate Dialkyl phosphates such as dipentyl phosphate, dihexyl phosphate, dipeptyl phosphate and dioctyl phosphate (the alkyl group may be linear or branched);
Di (alkyl) aryl phosphates such as diphenyl phosphate and dicresyl phosphate; trialkyl phosphates such as tripropyl phosphate, tributyl phosphate, tripentyl phosphate, trihexyl phosphate, tripeptyl phosphate and trioctyl phosphate (alkyl groups) May be linear or branched); tri (alkyl) aryl phosphates such as triphenyl phosphate and tricresyl phosphate; monopropyl phosphite, monobutyl phosphite, monopentyl phosphite, monohexyl phosphite Phosphite monoalkyl esters such as monophenyl phosphite, monooctyl phosphite, etc. (the alkyl group may be linear or branched); monophenyl phosphite, monocrete Phosphorous acid mono (alkyl) aryl esters such as Ruhosufaito; dipropyl phosphite, dibutyl phosphite, dipentyl phosphite,
Dialkyl phosphites such as dihexyl phosphite, dipeptyl phosphite and dioctyl phosphite (the alkyl group may be linear or branched); diphosphites such as diphenyl phosphite and dicresyl phosphite Alkyl) aryl esters; trialkyl phosphites such as tripropyl phosphite, tributyl phosphite, tripentyl phosphite, trihexyl phosphite, tripeptyl phosphite, and trioctyl phosphite; Triphenyl phosphite, tricresyl phosphite and the like; tri (alkyl) aryl phosphites; and mixtures thereof.

Examples of the salts of the above-mentioned phosphates and phosphites include phosphate monoesters, phosphate diesters, phosphite monoesters, phosphite diesters, and the like. Or a salt obtained by reacting a nitrogen-containing compound such as an amine compound containing only a hydrocarbon group having 1 to 8 carbon atoms or a hydroxyl group-containing hydrocarbon group in a molecule to neutralize a part or all of the remaining acidic hydrogen, etc. Is mentioned.

Specific examples of the nitrogen-containing compound include ammonia; monomethylamine, monoethylamine, monopropylamine, monobutylamine, monopentylamine, monohexylamine, monoheptylamine, monooctylamine, dimethylamine, and the like. Methylethylamine, diethylamine, methylpropylamine, ethylpropylamine, dipropylamine, methylbutylamine, ethylbutylamine, propylbutylamine,
Alkylamines such as dibutylamine, dipentylamine, dihexylamine, diheptylamine and dioctylamine (the alkyl group may be linear or branched); monomethanolamine, monoethanolamine, monopropanolamine, monobutanolamine, Monopentanolamine, monohexanolamine, monoheptanolamine, monooctanolamine, monononanolamine, dimethanolamine, methanolethanolamine, diethanolamine, methanolpropanolamine, ethanolpropanolamine, dipropanolamine, methanolbutanolamine, ethanolbutanol Amine, propanol butanolamine, dibutanolamine, dipentanolamine, dihexanolamine, diheptano Amines, alkanolamines such as di-octanol amine (alkanol group may be and straight-chain or branched); and mixtures thereof.

As the phosphorus compound, a compound selected from phosphoric esters, phosphites, and salts thereof is used. From the viewpoint of excellence, it is more preferable to use a compound selected from phosphate esters and salts of phosphate esters. Further, the sulfur-based compound used as the component (B) of the present invention includes:
Specific examples include dihydrocarbyl polysulfide, sulfurized esters (including sulfurized fats and oils), and sulfurized mineral oils.

As the component (B) of the present invention, a phosphorus compound and / or a sulfur compound is used, but a phosphorus compound is preferably used because of its better sludge resistance. Further, in the present invention, a mixture in which two or more compounds selected from the above-mentioned phosphorus compounds and sulfur compounds are mixed at an arbitrary ratio may be used.

(B) in the hydraulic oil composition of the present invention
The upper limit of the content of the component is 10% by mass based on the total amount of the composition.
, Preferably 5% by mass, more preferably 3% by mass, and most preferably 1% by mass. Even if the content of the component (B) exceeds 10% by mass, no further improvement in the frictional properties commensurate with the content is observed, and the sludge resistance is lowered, which is not preferable. On the other hand, the lower limit of the content of the component (B) is 0.01% by mass, preferably 0.05% by mass, more preferably 0.1% by mass based on the total amount of the composition.
It is. When the content of the component (B) is less than 0.01% by mass, the effect of adding the component is not observed, and the frictional characteristics of the hydraulic oil composition may be deteriorated.

The component (C) of the present invention is a compound represented by the following general formula (1). R ¹ —CH ₂ COOH (1) (wherein, R ¹ is an alkyl group having 7 to 29 carbon atoms,
To 29-alkenyl groups or groups represented by general formula (2). R ² —C ₆ H ₄ O— (2) (wherein, R ² represents an alkyl group having 1 to 20 carbon atoms or hydrogen).

In the general formula (1), R ¹ represents an alkyl group having 7 to 29 carbon atoms, an alkenyl group having 7 to 29 carbon atoms or a group represented by the general formula (2). The alkyl group represented by R ¹ needs to have 7 to 29 carbon atoms. From the viewpoint of solubility in a base oil, it is necessary that the carbon number is 7 or more, and it is preferable that the carbon number is 9 or more. Further, from the viewpoint of storage stability and the like, it is necessary that the number of carbon atoms be 29 or less, preferably 22 or less, and more preferably 19 or less. As such an alkyl group, specifically, for example, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group,
Hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group and the like (the alkyl group may be linear or branched).

The alkenyl group represented by R ¹ needs to have 7 to 29 carbon atoms. From the viewpoint of solubility in a base oil, it is necessary that the carbon number is 7 or more, and it is preferable that the carbon number is 9 or more. Further, from the viewpoint of storage stability and the like, it is necessary that the number of carbon atoms be 29 or less, preferably 22 or less, and more preferably 19 or less. As such an alkenyl group, specifically, for example, a heptenyl group, an octenyl group, a nonenyl group, a decenyl group, an undecenyl group, a dodecenyl group, a tridecenyl group, a tetradecenyl group, a pentadecenyl group, a hexadecenyl group, a heptadecenyl group, an octadecenyl group, Nonadecenyl group and the like (these alkenyl groups may be linear or branched).

In the general formula (2), R ² represents an alkyl group having 1 to 20 carbon atoms or hydrogen. The alkyl group represented by R ² needs to have 20 or less carbon atoms, preferably has 19 or less carbon atoms, and more preferably has 15 or less carbon atoms from the viewpoint of storage stability and the like. Also,
It is preferably at least 3 carbon atoms, more preferably at least 5 carbon atoms from the viewpoint of solubility in a base oil. In the case where R ² is an alkyl group, the position of substitution is arbitrary, but it is preferably in the para or meta position, more preferably in the para position, from the viewpoint of improving the frictional characteristics. In the general formula (1), as described above, even if R ¹ is an alkyl group having 7 to 29 carbon atoms or an alkenyl group having 7 to 29 carbon atoms, it is represented by the general formula (2). The group may be a group, but is preferably a group represented by the general formula (2) from the viewpoint of more excellent friction characteristics.

In the hydraulic oil composition of the present invention,
The content of the component (C) is optional, but if it is added in a large amount, the sludge resistance may decrease. Therefore, the content is preferably 5% by mass or less based on the total amount of the composition, and is preferably 1% by mass. % Or less, more preferably 0.5% or less.
Even more preferably, it is not more than mass%. On the other hand, it is preferably 0.001% by mass or more, more preferably 0.003% by mass or more, and more preferably 0.005% by mass or more based on the total amount of the composition, from the viewpoint of sufficiently exhibiting the effect of improving the friction characteristics. Even more preferably, it is not less than mass%.

The hydraulic oil composition of the present invention contains the above components (A) to (C) in the base oil and substantially does not contain zinc dithiophosphate (ZnDTP). When ZnDTP is contained, not only the sludge resistance is lowered but also the effect of improving the frictional characteristics is not seen, which is not preferable. In addition, it means that ZnD is not substantially contained.
It is less than the amount at which the effect of adding TP does not appear, and is not particularly limited to a numerical value.
The content of P is 0.001% by mass or less based on the total amount of the composition.

In the present invention, as described above, the lubricating base oil contains a specific amount of each of the component (A), the component (B) and the component (C), so that the lubricating base oil has excellent sludge resistance and friction characteristics. Although a Zn-based hydraulic fluid composition can be obtained, for the purpose of further improving its performance, a rust inhibitor, a metal deactivator, a viscosity index improver, a pour point depressant, Various additives represented by foaming agents and the like may be contained alone or in combination of several kinds.

Specific examples of the rust inhibitor include metal soaps such as fatty acid metal salts, lanolin fatty acid metal salts, and oxidized wax metal salts; polyhydric alcohol partial esters such as sorbitan fatty acid esters; and lanolin fatty acid esters. Esters; sulfonates such as calcium sulfonate and barium sulfonate; oxidized wax; amines; phosphoric acid; In the present invention, one or two or more compounds arbitrarily selected from these rust inhibitors can be contained in an arbitrary amount. It is desirably 0.01 to 1% by mass based on the total amount of the substance.

Specific examples of the metal deactivator include benzotriazole compounds, thiadiazole compounds, imidazole compounds and the like. In the present invention, one or two or more compounds arbitrarily selected from these metal deactivators can be contained in an arbitrary amount. It is preferably 0.001 to 1% by mass based on the total amount of the oil composition. Specific examples of the viscosity index improver include a copolymer of one or more monomers selected from various methacrylates or a hydrogenated product thereof, and an ethylene-α-olefin copolymer (as α-olefin). Can be exemplified by propylene, 1-butene, 1-pentene, etc.) or its hydride, polyisobutylene or its hydrogenated product, hydrogenated styrene-diene copolymer, and so-called non-dispersion type viscosities such as polyalkylstyrene. An index improver and the like can be exemplified. In the present invention, one or two or more compounds arbitrarily selected from these viscosity index improvers can be contained in an optional amount. 0.01 to 10 based on the total amount of the composition
Desirably, it is mass%.

Specific examples of the pour point depressant include copolymers of one or more monomers selected from various acrylates and methacrylates, and hydrogenated products thereof. In the present invention, one or two or more compounds arbitrarily selected from these pour point depressants can be contained in an arbitrary amount. It is desirable that the content is 0.01 to 5% by mass based on the total amount of the composition. Specific examples of the antifoaming agent include silicones such as dimethyl silicone and fluorosilicone. In the present invention, one or two or more compounds arbitrarily selected from these defoaming agents can be contained in an arbitrary amount. It is desirably 0.001 to 0.05% by mass based on the total amount of the substance.

The hydraulic fluid composition of the present invention is particularly preferably used as a hydraulic fluid used in hydraulic equipment such as injection molding machines, machine tools, construction machines, and steelmaking equipment. For example, it shows good performance as a hydraulic oil for hydraulic equipment such as industrial robots and hydraulic elevators.

[0057]

EXAMPLES Hereinafter, the content of the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

[Examples 1 to 3 and Comparative Examples 1 to 7] The hydraulic oil compositions according to the present invention were prepared according to the compositions shown in Table 1 (Examples 1 to 3). Further, compositions for comparison were prepared according to the compositions shown in Table 2 (Comparative Examples 1 to 7). The components used in the examples and comparative examples are as follows. Base oil hydrorefined paraffinic mineral oil (kinematic viscosity 46 mm ² / s (@ 40 ° C.), viscosity index 102, pour point -12.5 ° C.) (A) Component A1: 2,6-di-tert-butyl-p -Cresol A2: 4-butyl-4'-octyldiphenylamine (B) component B1: tricresyl phosphate B2: dioctyl phosphate (C) component C1: oleic acid C2: nonylphenoxyacetic acid

The compositions of these Examples and Comparative Examples were evaluated for sludge resistance and friction characteristics by the following test methods. The results are shown in Tables 1 and 2. Sludge resistance: Thermal stability test In accordance with the “Lubricant thermal stability test method” specified in JIS K 2540, sample oil was placed in a 50 ml beaker.
5 g of each sample was collected, copper and iron catalysts were put therein, left in a thermostat at 140 ° C. for 480 hours, and the amount of sludge in the sample oil was measured. The amount of sludge generated was determined by n-
It was determined by diluting with hexane, filtering through a 0.8 μm membrane filter, and measuring the weight of the collected matter.
For copper and iron catalysts, turbine oil oxidation stability test (JI
8 volumes of the catalyst used for the S.K.
5 cm) was used. Friction characteristics: Ball-on-disk friction test Using an SRV tester manufactured by Optimol, 1/2 inch SUJ2 steel ball and SUJ2 disk (φ10 mm)
The coefficient of friction between them was measured. The test conditions were a load of 200N,
The amplitude was 1.5 mm and the frequency was 50 Hz. Test start 15
The friction coefficient after one minute was measured.

[0060]

[Table 1]

[0061]

[Table 2]

Tables 1 and 2 show that the hydraulic oil compositions of the present invention (Examples 1 to 3) are superior to the compositions of Comparative Examples 1 to 7 in that they are significantly superior in sludge resistance and friction characteristics. It can be seen that it has excellent performance.

[0063]

The hydraulic fluid composition of the present invention has excellent friction characteristics, so that it can effectively reduce the resistance of sliding parts in a hydraulic system and has excellent sludge resistance. Therefore, troubles such as filter clogging due to sludge generation can be avoided.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) C10M 133/12 C10M 133/12 135/06 135/06 135/22 135/22 135/26 135/26 135 / 28 135/28 137/02 137/02 137/04 137/04 137/08 137/08 // C10N 30:04 C10N 30:04 30:10 30:10 40:08 40:08 (72) Inventor Yoshinobu Kikuchi 8 Chidori-cho, Naka-ku, Yokohama-shi, Kanagawa Prefecture Nishiishi Mitsui Co., Ltd. Lubricants Department Lubricants Research Laboratory F-term (reference) 4H104 BB05C BB17C BB19C BB35C BE07C BG04C BG12C BG14C BG15C BH02C BH03C BH05C DA02A DA06A

Claims (1)

[Claims] 1. A base oil comprising at least one selected from mineral oils, fats and oils and synthetic oils, wherein (A) 0.01 to 5% by mass of a phenolic antioxidant and / or an amine antioxidant, B) Phosphorus compound and / or sulfur compound is added in an amount of 0.
And (C) 0.001% by mass of the compound represented by the following general formula (1).
A hydraulic oil composition comprising about 5% by mass and substantially no zinc dithiophosphate. R ¹ —CH ₂ COOH (1) (wherein, R ¹ is an alkyl group having 7 to 29 carbon atoms,
To 29-alkenyl groups or groups represented by general formula (2). R ² —C ₆ H ₄ O— (2) (wherein, R ² represents an alkyl group having 1 to 20 carbon atoms or hydrogen).