WO2020213504A1

WO2020213504A1 - Hydraulic oil for hydraulic device and hydraulic device that uses said hydraulic oil for hydraulic device

Info

Publication number: WO2020213504A1
Application number: PCT/JP2020/015893
Authority: WO
Inventors: 一等杉本; 竜壮芦沢; 拓小野寺; 佳恵酒井; 弘晃橘
Original assignee: 日立オートモティブシステムズ株式会社
Priority date: 2019-04-19
Filing date: 2020-04-08
Publication date: 2020-10-22
Also published as: JP7261074B2; JP2020176224A

Abstract

The purpose of the present invention is to provide a hydraulic oil for a hydraulic device, e.g., an automotive shock absorber, the hydraulic oil allowing the individual components to stably present for the long term and reducing fluctuation in the friction coefficient during long-term use. The hydraulic oil for a hydraulic device according to the present invention comprises: a base oil; at least one selected from the group consisting of phosphite ester compounds and phosphate ester compounds; a primary amine compound; and a compound having a glycidyl group or epoxy group, and is characterized in that the content of the at least one selected from the group consisting of phosphite ester compounds and phosphate ester compounds exceeds 0.1 mass% with reference to the total of the base oil and the at least one selected from the group consisting of phosphite ester compounds and phosphate ester compounds, the molar ratio of the primary amine compound to the at least one selected from the group consisting of phosphite ester compounds and phosphate ester compounds is 30% to 500%, and the molar ratio of the compound having a glycidyl group or epoxy group to the at least one selected from the group consisting of phosphite ester compounds and phosphate ester compounds, is 10% to 500%.

Description

Hydraulic system using hydraulic oil for hydraulic system and its hydraulic oil for hydraulic system

The present invention relates to a hydraulic oil for a hydraulic system and a hydraulic system using the hydraulic oil for the hydraulic system.

In a hydraulic system equipped with a piston rod, an oil seal, and hydraulic oil, the oil seal is arranged so as to be in constant contact with the piston rod, and plays a role of preventing the hydraulic oil from flowing out from the inside of the hydraulic system.

Since the oil seal is made of a rubber-based material, the contact surface with the piston rod surface made of metal has a large coefficient of friction. Therefore, when the piston rod reciprocates in the hydraulic system, a large frictional force is generated between the oil seal and the piston rod.

If the frictional force generated between the oil seal and the piston rod is too large, the piston rod will not move smoothly. In particular, in an automobile shock absorber (shock absorber), a large frictional force is applied to the oil seal from a direction perpendicular to the reciprocating direction of the piston rod due to the movement of the vehicle body such as turning and acceleration / deceleration. The environment is prone to occur.
Therefore, in an automobile to which an automobile shock absorber having a large coefficient of friction between the oil seal and the piston rod is applied, the vibration caused by the unevenness of the road surface is transmitted to the passenger without being sufficiently damped, resulting in an uncomfortable ride. There is.

Attempts have been made to appropriately reduce the frictional force between the oil seal and the piston rod by adding additives to the hydraulic oil of the shock absorber for automobiles in order to improve the riding comfort.

For example, Patent Document 1 discloses a lubricating oil composition that exhibits a friction reducing effect by blending a specific sulfur-containing compound and a specific polar group-containing compound in the base oil. As the polar group-containing compound, a compound having at least one polar group selected from an amino group, an amide group and a hydroxyl group and an alkyl group having 3 to 24 carbon atoms is disclosed. Further, Patent Document 1 discloses that a substance containing a phosphoric acid ester compound and a phosphite ester compound can be added as an abrasion resistant agent or an extreme pressure agent.

International Publication No. 2011/068137

As described in Patent Document 1, the coefficient of friction between the oil seal and the piston rod is arbitrarily reduced by the phosphate ester compound and the phosphite ester compound blended in the hydraulic oil of the shock absorber for automobiles, and the ride comfort is achieved. Can be adjusted. The coefficient of friction described above is adjusted to be slightly higher when, for example, steerability is important, and lower when riding comfort is important. However, although the phosphoric acid ester compound and the phosphite ester compound are excellent in the ability to adjust the coefficient of friction, they are easily deactivated due to aged deterioration. In general, the hydraulic oil contained in an automobile shock absorber continues to be used from the time of automobile manufacturing to the time of automobile disposal without being replaced even once. The average age of automobiles is increasing year by year, and according to a survey by the Automobile Inspection & Registration Information Association, it has reached about 14 years as of 2017. Therefore, when a conventional hydraulic oil for a shock absorber containing a phosphoric acid ester compound or a phosphite ester compound is used for an automobile shock absorber, the phosphoric acid ester compound or phosphite ester compound or phosphite ester is deteriorated over time due to such long-term use. As a result of the inactivation of the acid ester compound, the friction coefficient increases as compared with the initial use, and the riding comfort deteriorates. Therefore, especially in a hydraulic device such as an automobile shock absorber, it is desired to reduce the fluctuation of the friction coefficient between the oil seal and the piston rod due to long-term use.

In view of the above-mentioned conventional situation, the present invention uses a hydraulic oil for a hydraulic device such as a shock absorber for automobiles in which each component is stably present for a long period of time and the fluctuation of the friction coefficient due to long-term use is small, and the hydraulic oil thereof. It is an object of the present invention to provide a hydraulic system.

In order to solve the above problems, the hydraulic oil for a hydraulic device of the present invention includes a base oil, at least one selected from the group consisting of a phosphite ester compound and a phosphate ester compound, a primary amine compound, and a glycidyl group or. The content of at least one selected from the group consisting of the phosphite ester compound and the phosphate ester compound, which includes a compound having an epoxy group, is the base oil and the phosphite ester compound and the phosphate ester compound. More than 0.1% by mass with respect to the total of at least one selected from the group consisting of, and the molar amount of the primary amine compound with respect to at least one selected from the group consisting of the phosphite ester compound and the phosphate ester compound. The ratio is 30% or more and 500% or less, and the molar ratio of the compound having a glycidyl group or an epoxy group to at least one selected from the group consisting of the phosphite ester compound and the phosphoric acid ester compound is 10% or more and 500%. It is characterized by the following.

Further, the present invention is a hydraulic device including the above-mentioned hydraulic oil for a hydraulic device.
This specification includes the disclosure content of Japanese Patent Application No. 2019-080229, which is the basis of the priority of the present application.

According to the present invention, a hydraulic oil for a hydraulic system in which each component exists stably for a long period of time and the coefficient of friction generated between the oil seal and the piston rod can be maintained for a long period of time, and a hydraulic system using the hydraulic oil for the hydraulic system. Can be provided.
Issues, configurations and effects other than those described above will be clarified by the description of the following embodiments.

It is sectional drawing of the shock absorber for automobile which concerns on one Embodiment of this invention. It is the schematic of the reciprocating friction tester used for estimating the frictional force between an oil seal and a piston rod.

Hereinafter, the present invention will be described in detail based on the embodiments.
The hydraulic fluid for a hydraulic device according to an embodiment of the present invention includes (A) a base oil, (B) at least one selected from the group consisting of a phosphite ester compound and a phosphate ester compound, and (C) first grade. The content of at least one selected from the group consisting of the phosphite ester compound and the phosphate ester compound, which comprises an amine compound and (D) a compound having a glycidyl group or an epoxy group, is the base oil and the above. It is more than 0.1% by mass based on the total of at least one selected from the group consisting of the phosphite ester compound and the phosphoric acid ester compound, and is selected from the group consisting of the sulphate ester compound and the phosphoric acid ester compound. The molar ratio of the primary amine compound to at least one of the compounds is 30% or more and 500% or less, and the glycidyl group or epoxy group is added to at least one selected from the group consisting of the phosphite ester compound and the phosphate ester compound. The molar ratio of the compound is 10% or more and 500% or less.

As the base oil of the above (A), any material can be selected from the mineral oil-based and / or synthetic oil-based base oils conventionally used as hydraulic oils for hydraulic systems. Examples of the mineral oil-based base oil include paraffin-based mineral oil and naphthenic mineral oil.

Examples of synthetic oil-based base oils include polybutene, polypropylene, polyα-olefin, polyol ester, fatty acid monoester, aromatic monoester, fatty acid diester, aliphatic polybasic acid ester, aromatic polybasic acid ester, and polyol polyester. , Esters such as phosphoric acid esters, polyalkylene glycols, polyphenyl ethers, polyglycols, alkylbenzenes, synthetic naphthenes, ionic liquids and the like.

Among these base oils, as the base oil in the present embodiment, paraffin-based mineral oil, naphthen-based mineral oil, poly-α-olefin, polyphenyl ether, alkylbenzene, synthetic naphthen, silicone, polyalkylene glycol and the like are preferable. Any one of these base oils may be used alone, or two or more thereof may be used in combination.

The preferred kinematic viscosity of the base oil varies depending on the hydraulic system to which the hydraulic oil for the hydraulic system is applied. For example, when the hydraulic system is an automobile shock absorber, the kinematic viscosity at 40 ° C. (from the viewpoint of fluidity in a low temperature state) The test based on ISO3448: 1992) is preferably in the range of 8 mm ² / s (cSt) or more and 17 mm ² / s (cSt) or less.

As the material of the above (B), at least one selected from the group consisting of a phosphite ester compound and a phosphoric acid ester compound is used. In both the phosphoric acid ester compound and the phosphite ester compound, the phosphate group and / or the phosphite group releases protons by the catalytic action of the metal exposed on the surface of the piston rod and is adsorbed on the surface of the piston rod to be stable. Form an esterified film. The thickness of the formed adsorption film depends on the length of the alkyl group of the phosphate ester compound and the phosphite ester compound. By changing the length of the alkyl group, the thickness of the adsorption membrane can be controlled, and the coefficient of friction generated between the piston rod and the oil seal can be arbitrarily adjusted.

The phosphite ester compound used as the material of the above (B) preferably has a structure represented by the following formula (1). In the formula (1), one of R ₁ and R ₂ is hydrogen or a hydrocarbon group having 3 or more and 30 or less carbon atoms, and the other is a hydrocarbon group having 3 or more and 30 or less carbon atoms. From the viewpoint of solubility, it is more preferable that the number of carbon atoms is 3 or more and 18 or less. These hydrocarbon groups may be alkyl groups which are saturated hydrocarbon groups, or unsaturated hydrocarbon groups such as alkenyl groups. One may be a saturated hydrocarbon group and the other may be an unsaturated hydrocarbon group.

Further, the phosphoric acid ester compound used as the material of the above (B) preferably has a structure represented by the following formula (2). In formula (2), R ₃ and R _4, one is hydrogen or a hydrocarbon group having 3 to 30 carbon atoms, the other is a hydrocarbon group having 3 to 30 carbon atoms. The above carbon number is more preferably 3 or more and 18 or less. These hydrocarbon groups may be alkyl groups which are saturated hydrocarbon groups, or unsaturated hydrocarbon groups such as alkenyl groups. One may be a saturated hydrocarbon group and the other may be an unsaturated hydrocarbon group.

Examples of the saturated hydrocarbon group in the above phosphite ester compound and phosphoric acid ester compound include alkyl groups such as diethylhexyl group, lauryl group, myristyl group, cetyl group and stearyl group. Further, examples of the unsaturated hydrocarbon group include an oleyl group and the like. R ₁ , R ₂ , R ₃ and R ₄ may all be the same hydrocarbon group or may be different hydrocarbon groups. Alternatively, some of R ₁ , R ₂ , R ₃ and R ₄ may be the same hydrocarbon group, and the others may be composed of different hydrocarbon groups. As the phosphite ester compound and / or the phosphoric acid ester compound used as the material of (B), any one of them may be used alone, or a plurality of kinds of the phosphite ester compound and / or the phosphoric acid ester compound may be used. It may be mixed and used.

Specific examples of the phosphite ester compound used as the material of (B) include diethylhexyl hydrogen phosphite, dilauryl hydrogen phosphite, distearyl hydrogen phosphite, dioleyl hydrogen phosphite and the like.
In particular, Georail hydrogen phosphite is preferably used. Examples of the phosphoric acid ester compound used as the material of (B) include ethylhexyl acid phosphate, lauryl acid phosphate, stearyl acid phosphate, and oleyl acid phosphate.

The blending amount of the material (B) is more preferably 0.3% by mass or more and 5.0% by mass or less with respect to the total of the base oil of (A) and the material of (B). The material (B) exerts its effect when it is blended in an amount of more than 0.1% by mass, and exerts a sufficient effect when it is blended in an amount of 0.3% by mass or more. Further, the same effect is exhibited even if the blending amount exceeds 5.0% by mass, but the blending amount is preferably 5.0% by mass or less from the viewpoint of maintaining good solubility in the base oil. ..

As the primary amine compound used as the material of (C), any compound in which one of the hydrogen atoms of ammonia is replaced with a hydrocarbon group or an aromatic group can be applied. Preferably, a compound represented by the following formula (3) is used as the primary amine compound. In formula (3), _{R 5} is a saturated or unsaturated hydrocarbon group having 12 to 30 carbon atoms. However, from the viewpoint of ensuring good solubility in the base oil, the carbon number of these hydrocarbon groups is more preferably 12 or more and 22 or less. Examples of such saturated hydrocarbon groups include alkyl groups such as dodecyl group, myristyl group, cetyl group and stearyl group. Further, examples of the unsaturated hydrocarbon group include an alkenyl group such as an oleyl group and an elsyl group.

The phosphite ester compound and the phosphoric acid ester compound, which are the materials of the above (B), produce an acidic phosphoric acid ester compound due to deterioration due to long-term use. Since such an acidic phosphoric acid ester compound has high reactivity and attacks the phosphite ester compound and the phosphoric acid ester compound of the above (B), the deterioration of the material of (B) progresses in a chain reaction. The primary amine compound (C) prevents the chain deterioration reaction of the material (B) by capturing the acidic phosphoric acid ester compound, and maintains the coefficient of friction between the oil seal and the piston rod for a long period of time. enable.

Specific examples of the material of (C) above include dodecylamine, palmitylamine, palmitrailamine, oleylamine and the like. Oleylamine is particularly preferably used.

Regarding the blending amount of the primary amine compound which is the material of (C), the molar ratio of the primary amine compound to the material of (B) is 30% or more and 500% or less, preferably 50% or more and 300% or less. The effect is exhibited when the molar ratio of the primary amine compound (C) is 30% or more, and a sufficient effect is exhibited when the compound is blended in the range of 50% or more and 300% or less. The same effect is exhibited even if the molar ratio exceeds 300%, but the excessively blended primary amine compound does not sufficiently dissolve in the base oil and has an adverse effect of inhibiting the surface adsorption of the phosphite ester compound. Therefore, the molar ratio is more preferably 300% or less.

Any compound can be used as the compound having a glycidyl group or an epoxy group as the material of (D), and in particular, the glycidyl ether represented by the following formula (4) is preferably used. In the formula (4), R ₆ is a saturated or unsaturated hydrocarbon group having 3 to 30 carbon atoms. However, from the viewpoint of ensuring good solubility in the base oil, the carbon number of these hydrocarbon groups is more preferably 8 or more and 22 or less. Examples of such a hydrocarbon group include alkyl groups such as lauryl group, myristyl group, cetyl group and stearyl group.
Moreover, as an unsaturated hydrocarbon group, an alkenyl group such as an oleyl group and an elsyl group can be mentioned.

Specific examples of the material of (D) above include butyl glycidyl ether, octyl glycidyl ether, stearyl glycidyl ether and the like. Particularly preferred is octylglycidyl ether.

As described above, the primary amine compound, which is the material of (C), traps the acidic phosphoric acid ester compound to cause a chain deterioration reaction of the phosphite ester compound and / or the phosphoric acid ester compound of (B). Preventing (B) allows the ability to regulate friction between the oil seal and the piston rod to be maintained for extended periods of time. However, at the same time, the primary amine compound of (C) has aggression against the phosphite ester compound and / or the phosphate ester compound of (B). Therefore, in the hydraulic equipment for hydraulic equipment in which only (B) a phosphite ester compound and / or a phosphoric acid ester compound and (C) a primary amine compound are mixed with (A) base oil, it is possible to use it for a long period of time. The effect of (B) the subphosphate compound and / or the phosphate compound is deactivated by the attack by the (C) primary amine compound, and the frictional force is increased. Here, by blending the above-mentioned compound having a glycidyl group or an epoxy group, which is the material of (D), with the hydraulic oil for a hydraulic device, the decomposition reaction of the above-mentioned (B) phosphite ester compound or phosphoric acid ester compound. Can be suppressed. As a result, the acidic phosphoric acid ester compound generated by the deterioration of the (B) phosphite ester compound and / or the phosphoric acid ester compound is captured by the primary amine compound of (C), thereby suppressing the chain deterioration reaction while suppressing the chain deterioration reaction. (C) Decomposition of (B) phosphite ester compound and / or phosphoric acid ester compound due to attack by primary amine compound is also suppressed at the same time, and the friction coefficient generated between the oil seal and the piston rod is kept unchanged for a long period of time. be able to.

Regarding the blending amount of the compound having a glycidyl group or an epoxy group which is the material of (D), the molar ratio of the compound having a glycidyl group or an epoxy group to the material of (B) is 10% or more and 500% or less, preferably. It is 50% or more and 300% or less. The effect is exhibited when the molar ratio of the compound having the glycidyl group or the epoxy group of (D) is 10% or more, and a sufficient effect is exhibited when the compound is blended in an amount of 50% or more. Further, the same effect is exhibited even if the molar ratio exceeds 300%, but the molar ratio is preferably 300% or less from the viewpoint of maintaining good solubility in the base oil.

Further, the hydraulic oil for the hydraulic system according to the present embodiment can further contain a secondary amide compound represented by the following formula (5), if necessary. In the formula (5), R ₇ and R ₈ are each independently saturated or unsaturated hydrocarbon group having 8 or more and 24 or less carbon atoms. However, from the viewpoint of ensuring good solubility in the base oil, the carbon number of these hydrocarbon groups is more preferably 12 or more and 22 or less. Examples of such saturated hydrocarbon groups include alkyl groups such as dodecyl group, myristyl group, cetyl group and stearyl group. Further, examples of the unsaturated hydrocarbon group include an alkenyl group such as an oleyl group and an elsyl group.

Specific examples of the above secondary amide compound include N-stearyl oleic acid amide, N-stearyl erucic acid amide, N-cetyl oleic acid amide, N-cetyl erucic acid amide, N-myristyl oleic acid amide, and N-. Examples thereof include myristyl ercylic acid amide, N-dodecyl oleic acid amide, and N-dodecyl ercylic acid amide.

Regarding the blending amount of the secondary amide compound, the total amount of the base oil of (A), at least one selected from the group consisting of the phosphite ester compound of (B) and the phosphoric acid ester, and the secondary amide compound , 0.01% by mass or more and 2.0% by mass or less is preferable.

Additives may be appropriately added to the hydraulic oil for the hydraulic system according to the present embodiment as long as the effect is not impaired. Specific additives include wear inhibitors, oiliness improvers, antioxidants, ashless dispersants, metal dispersants, viscosity index improvers, pour point depressants, metal defoamers, and rust preventives. , And antifoaming agents and the like.

Among these, the hydraulic oil for the hydraulic system according to the present embodiment is selected from the group consisting of antioxidants, ashless dispersants, metal dispersants, viscosity index improvers, rust preventives, and defoamers. It is preferable to contain at least one additive to be added.

Examples of the anti-wear agent include zinc dithiophosphate and its derivatives, sulfur compounds and their derivatives, molybdenum disulfide and its derivatives, and the like.

Examples of the oiliness improver include fatty alcohols and derivatives thereof, fatty acid esters and derivatives thereof, fatty acids and derivatives thereof, amine compounds and derivatives thereof, and the like.

Examples of the antioxidant include amine-based antioxidants and their derivatives, phenol-based antioxidants and their derivatives, sulfur-based antioxidants and their derivatives, carbamate-based antioxidants and their derivatives, and the like.

Examples of the ashless dispersant include succinic acid imide and its derivatives, benzylamine and its derivatives, esters and its derivatives, and the like.

Examples of the metal-based dispersant include calcium salicylate and its derivatives, calcium phenate and its derivatives, calcium sulfonate and its derivatives, potassium borate and its derivatives, and the like.

Examples of the viscosity index improver include polymethacrylate and its derivatives, polyisobutylene and its derivatives, olefin copolymers and their derivatives, and the like.

Examples of the pour point lowering agent include polymethacrylate and its derivative, polybutene and its derivative, polyalkylstyrene and its derivative, and the like.

Examples of the metal inactivating agent include benzotriazole and its derivatives, thiadiazole and its derivatives, and the like.

Examples of the rust preventive include imidazole and its derivatives, benzotriazole and its derivatives, thiadiazole and its derivatives, and the like.

Examples of the defoaming agent include silicone-based defoaming agents and their derivatives, polyacrylate-based defoaming agents and their derivatives, and the like.

It is preferable that the total amount of these various additives is less than 30% by mass of the total hydraulic oil for the hydraulic system.

Next, the configuration of the hydraulic system using the hydraulic oil for the hydraulic system according to the present embodiment will be described with reference to the drawings. Here, as the hydraulic system, a double-cylinder type shock absorber for automobiles will be described as an example.

FIG. 1 is a cross-sectional view of an automobile shock absorber 100 according to an embodiment of the present invention. The shock absorber 100 for automobiles is a double-cylinder type, and has a cylindrical outer cylinder 11 having a bottom, and a cylinder 1 composed of an inner cylinder 12 provided coaxially with the outer cylinder 11 inside the outer cylinder 11. It includes a piston rod 2 that can move relative to the cylinder 1. The hydraulic oil 3 for the hydraulic system is injected into the inside of the inner cylinder 12 and the space between the inner cylinder 12 and the outer cylinder 11.

Regarding the piston rod 2, the piston 4 is fixed to one end side of the piston rod 2 inserted into the inner cylinder 12, and the other end is arranged so as to protrude from the cylinder 1. The outer peripheral portion of the piston 4 comes into contact with the inner surface of the inner cylinder 12. A bottom valve 5 is fixed to the lower end of the inner cylinder 12, and a bush 6 is fixed to the upper end of the inner cylinder 12. A through hole is provided in the center of the bush 6, and the piston rod 2 is inserted into the through hole. An oil seal 7 is fixed to the upper part of the outer cylinder 11, and the inside of the outer cylinder 11 is sealed via the oil seal 7. The piston rod 2 is slidable with the oil seal 7, whereby the oil seal 7 prevents the hydraulic oil 3 for the hydraulic system from leaking to the outside of the cylinder 1 through the gap between the piston rod 2 and the bush 6. .. If necessary, chrome plating can be applied to at least a part of the surface of the piston rod 2. By providing chrome plating, wear can be prevented and the stability of sealing performance can be improved.

As shown in FIG. 1, in the automobile shock absorber 100, the piston 4 separates the inside of the inner cylinder 12 into the oil chamber A and the oil chamber B. Further, the bottom valve 5 separates the space between the inner cylinder 12 and the outer cylinder 11 from the oil chamber A. The piston 4 is provided with a damping force generating mechanism 8 provided with a valve. In the damping force generation mechanism 8, when the piston rod 2 moves to the extension side (the piston rod 2 moves upward in FIG. 1), the valve opens and the cross-sectional area between the oil chamber A and the oil chamber B is small. A predetermined damping force is generated by forming a flow path and limiting the flow of the hydraulic oil 3 for the hydraulic system. The bottom valve 5 is provided with a damping force generating mechanism 9. The damping force generation mechanism 9 is composed of a flow path having a small cross-sectional area formed on the bottom valve 5. When the piston rod 2 moves to the contraction side (the piston rod 2 moves downward in FIG. 1), the hydraulic oil 3 for the hydraulic system in the oil chamber A flows into the reservoir chamber C through a flow path having a small cross-sectional area. By doing so, a damping force is generated.

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

(1) Accelerated aging test An accelerated aging test was conducted to reproduce the deterioration of hydraulic oil for hydraulic systems due to aging.
A hydraulic oil for a hydraulic system having various compounding compositions shown in Examples or Comparative Examples described later was sealed in a pressure vessel, and an accelerated deterioration test was carried out for 120 hours in a constant temperature bath maintained at 120 ° C. In general, it is known that when the outside air temperature rises by 10 ° C., the deterioration of the material progresses twice as fast. Therefore, a 120-hour accelerated deterioration test at 120 ° C. can reproduce a deterioration state of about 14 years at 20 ° C. The hydraulic oil for the hydraulic system after the accelerated deterioration test was subjected to a reciprocating friction test described later, and the friction coefficients before and after the deterioration test were compared.

(2) Reciprocating friction test: In order to estimate the frictional force generated between the oil seal and the piston rod in the hydraulic system, a reciprocating friction tester is used to test hydraulic oil for hydraulic systems with various compounding compositions. It was. As the reciprocating dynamic friction tester, the Bowden tester HEIDON-14D type of Shinto Kagaku Co., Ltd. was used. FIG. 2 shows an outline of a test method using this reciprocating dynamic friction tester. The reciprocating friction tester 200 moves relative to the first test tool 22 on the reciprocating table 21, the first test tool 22 placed on the table 21, and the first test tool 22. It has a second test tool 23 that can be arranged, and a load application unit 24 that applies a load to the first test tool 22 via the second test tool 23. The first test tool 22 is fixed to the table 21, and the second test tool 23 is fixed to the load applying portion 24.

The first test tool 22 was made of chrome-plated carbon steel plate, which is the same material as the piston rod, and the second test tool 23 was made of nitrile butadiene rubber, which is the same material as the oil seal. A hydraulic oil 30 for a hydraulic system is interposed between the first test tool 22 and the second test tool 23, and the table 21 is reciprocated in this state to bring the first test tool 22 and the second test tool 23 together. The dynamic friction between them was measured. As the hydraulic oil 30 for the hydraulic system, those having various compounding compositions shown in Tables 1 and 2 are sequentially used, and the first test tool 22 and the second test tool when the respective hydraulic oils for the hydraulic system are used. The coefficient of dynamic friction with 23 was measured. In Tables 1 and 2, at least one selected from the group consisting of a phosphite ester compound and a phosphoric acid ester compound is referred to as a "phosphate ester compound", and a compound having a glycidyl group or an epoxy group is referred to as "". It is described as "epoxy compound". In Tables 1 and 2, "phosphate ester compound (1)" is a phosphite ester compound having the structure of diorail hydrogen phosphite in the formula (1), and "phosphate ester compound (2)" is , Dilauryl Hydrogenphosphite. The above test results corresponded to the frictional force between the piston rod and the oil seal, and the hydraulic oil for the hydraulic system having the above various compounding compositions was evaluated.

The conditions of the reciprocating dynamic friction test are as follows.
Test machine name used: Bowden tester HEIDON-14D type 1st test tool material: Chrome-plated carbon steel plate 2nd test tool material: Nitrile butadiene rubber [Test conditions] Test temperature: 60 ° C. Applied load of load application part: 20N Table operating amplitude: 10 mm Table speed: 2 mm / sec

Tables 1 and 2 show the results of measuring the friction coefficient before and after the accelerated deterioration test at a test temperature of 60 ° C. for hydraulic fluids having various compositions. As is clear from the test results for Examples 1 to 13 shown in Tables 1 and 2, the fluctuation of the coefficient of friction after the accelerated deterioration test measured by the reciprocating dynamic friction test is the same for all hydraulic fluids for hydraulic systems. Compared with the friction coefficient before the accelerated deterioration test, it is within about 0.03. Further, the value obtained by dividing the friction coefficient after the accelerated deterioration test by the friction coefficient before the accelerated deterioration test (friction coefficient ratio) is a value close to 1 (range of 0.89 to 1.28) in all the examples. there were. That is, the fluctuation of the friction coefficient due to the accelerated deterioration test is extremely small. From these results, the automobile shock absorbers using the hydraulic oil for the hydraulic system of Examples 1 to 13 have a coefficient of friction between the piston rod and the oil seal for about 14 years, which is the average usage period of the passenger car. It was suggested that it could be maintained almost constant.

On the other hand, the hydraulic oil for the hydraulic system of Comparative Example 1 has a composition of only the base oil, and does not contain any of the phosphate ester compound, the primary amine compound and the epoxy compound. The test results for Comparative Example 1 showed that the friction coefficient before the accelerated deterioration test was 0.729 and the friction coefficient after the accelerated deterioration test was 0.723, and the friction coefficient ratio before and after the accelerated deterioration test was as small as 0.99. However, on the other hand, the coefficient of friction between the piston rod and the oil seal is high. Therefore, when the hydraulic oil for the hydraulic system of Comparative Example 1 was used for the shock absorber for an automobile, the piston rod did not move smoothly, so that a rugged feeling was transmitted to the rider, suggesting that the ride quality was inferior.

The hydraulic oil for the hydraulic device of Comparative Example 2 contains a phosphite ester compound in the base oil, but the amount is as small as 0.1% by mass with respect to the total of the base oil and the phosphite ester compound. Is. Therefore, the friction coefficient before the accelerated deterioration test was 0.164, while the friction coefficient after the accelerated deterioration test was 0.493, which was significantly increased. Therefore, it was suggested that when the hydraulic oil for the hydraulic system of Comparative Example 2 was used for the shock absorber for automobiles, the riding comfort deteriorated after about 14 years, which is the average usage period of the passenger car.

In the hydraulic device for hydraulic equipment of Comparative Example 3, a phosphorate ester compound and an epoxy compound are blended in the base oil, but the blending amount (molar ratio) of the primary amine compound is higher than that of the phosphite ester compound. It is as small as 20%. The test results for Comparative Example 3 are that the friction coefficient before the accelerated deterioration test is 0.111, the friction coefficient after the accelerated deterioration test is 0.412, and the friction coefficient ratio before and after the accelerated deterioration test is 3.71. , The coefficient of friction increased significantly after the accelerated deterioration test. This is because the amount of the primary amine compound blended is insufficient, and the deterioration progresses in a chain reaction due to the decomposition products of the phosphite ester compound. Therefore, it was suggested that when the hydraulic oil for the hydraulic system of Comparative Example 3 was used for the shock absorber for automobiles, the riding comfort deteriorated after being used for about 14 years, which is the average usage period of the passenger car.

In the hydraulic device for hydraulic equipment of Comparative Example 4, a phosphite ester compound and a primary amine compound are blended in the base oil, and an epoxy compound is further blended in a molar ratio of 5% with respect to the phosphite ester compound. .. The test results for Comparative Example 4 were that the coefficient of dynamic friction before the accelerated deterioration test was 0.107, the coefficient of dynamic friction after the accelerated deterioration test was 0.298, and the coefficient of friction before and after the accelerated deterioration test was 2.79. , The coefficient of friction increased significantly after the accelerated deterioration test. This is because the amount of the epoxy compound compounded is insufficient, so that the decomposition reaction of the phosphite ester by the primary amine compound could not be sufficiently suppressed. Therefore, it was suggested that when the hydraulic oil for the hydraulic system of Comparative Example 4 was used for the shock absorber for automobiles, the riding comfort deteriorated after about 14 years, which is the average usage period of the passenger car.

As described above, when the hydraulic oil for the hydraulic system according to the embodiment of the present invention is used for the hydraulic system, the coefficient of dynamic friction generated between the oil seal and the piston rod is appropriately reduced, and the average of passenger cars is reduced. The coefficient of friction can be kept almost constant for about 14 years, which is a typical usage period.

(2) Sensory test using an automobile equipped with a shock absorber for automobiles An accelerated deterioration test was conducted at 120 ° C. for 120 hours on hydraulic oils for hydraulic systems having two types of compounding compositions according to Example 1 and Comparative Example 1. , An automobile shock absorber filled with hydraulic oil before and after the test was prepared. A car equipped with this car shock absorber was moved, and a sensory test was conducted on its riding comfort. Specifically, two testers who perform sensory tests board a car equipped with a shock absorber for automobiles filled with hydraulic oil for hydraulic equipment before and after the accelerated deterioration test, and vibration caused by unevenness of the road surface is generated. The degree of transmission was evaluated on a scale of 5 points. The higher the evaluation score (the higher the number), the better the ride quality. The average score of the evaluation scores of the two examiners was used as the final evaluation score. The results are shown in Table 3.

As shown in Table 3, the automobile equipped with the automobile shock absorber filled with the hydraulic oil for the hydraulic system according to the first embodiment is equipped with the automobile shock absorber filled with the hydraulic oil for the hydraulic device shown in Comparative Example 1. It was found that the ride quality was superior to that of automobiles even after the accelerated deterioration test. It is presumed that this result is because the friction coefficient is kept low even after the accelerated deterioration test in Example 1.

In addition, even in an automobile equipped with a shock absorber for an automobile using the hydraulic oil for the hydraulic system of Examples other than Example 1, before and after the accelerated deterioration test as in the case of using the hydraulic oil for the hydraulic system of Example 1. The result is that the fluctuation of the riding comfort is small. Further, even in an automobile equipped with an automobile shock absorber using the hydraulic oil for the hydraulic system of the comparative example other than Comparative Example 1, before and after the accelerated deterioration test as in the case of using the hydraulic oil for the hydraulic system of Comparative Example 1. The result is that the ride quality fluctuates greatly.

As described above, according to the present invention, it is possible to provide a hydraulic oil for a hydraulic system in which the friction coefficient between the oil seal and the piston rod is reduced over a long period of time and the fluctuation of the friction coefficient is small. Further, it is possible to provide a hydraulic device using the hydraulic oil for the hydraulic device. An automobile equipped with an automobile shock absorber using the hydraulic oil according to the present invention can reduce the degree to which vibration caused by unevenness of the road surface is transmitted to the passenger for a long period of time, and can maintain a good riding comfort.

The present invention is not limited to the embodiments described above. Specific constituent materials, parts, and the like may be changed without changing the gist of the present invention. Further, if the components of the present invention are included, it is possible to add a known technique or replace it with a known technique.

1 ... Cylinder, 2 ... Piston rod, 3 ... Hydraulic oil for hydraulic system, 4 ... Piston, 5 ... Bottom valve, 6 ... Bush, 7 ... Oil seal, 8, 9 ... Damping force generation mechanism, 11 ... Outer cylinder, 12 ... Inner cylinder, 21 ... Table, 22 ... 1st test tool, 23 ... 2nd test tool, 24 ... Load application part, 30 ... Hydraulic system hydraulic oil, 100 ... Automotive shock absorber, 200 ... Reciprocating dynamic friction tester All publications, patents and patent applications cited herein shall be incorporated herein by reference as is.

Claims

Base oil and
At least one selected from the group consisting of phosphite ester compounds and phosphoric acid ester compounds,
With primary amine compounds
Containing compounds having a glycidyl group or an epoxy group,
The content of at least one selected from the group consisting of the phosphite ester compound and the phosphoric acid ester compound is at least one selected from the group consisting of the base oil and the phosphite ester compound and the phosphoric acid ester compound. It is more than 0.1% by mass with respect to the total.
The molar ratio of the primary amine compound to at least one selected from the group consisting of the phosphite ester compound and the phosphoric acid ester compound is 30% or more and 500% or less.
A hydraulic oil for a hydraulic device, wherein the molar ratio of the compound having a glycidyl group or an epoxy group to at least one selected from the group consisting of the phosphite ester compound and the phosphoric acid ester compound is 10% or more and 500% or less.
The phosphite ester compound has the formula (1).

(In the formula (1), one of R 1 and R 2 is hydrogen or a saturated or unsaturated hydrocarbon group having 3 or more and 30 or less carbon atoms, and the other is a saturated or unsaturated hydrocarbon having 3 or more and 30 or less carbon atoms. It is represented by)
The phosphoric acid ester compound is represented by the formula (2).

(In formula (2), R 3 and R 4, one is a saturated or unsaturated hydrocarbon group having hydrogen or having 3 to 30 carbon atoms and the other is saturated or unsaturated hydrocarbons having 3 to 30 carbon atoms The hydraulic fluid for a hydraulic device according to claim 1, which is represented by ().
The primary amine compound is represented by the formula (3).

(In the formula (3), R 5 is a saturated or unsaturated hydrocarbon group having 12 to 30 carbon atoms.) Represented by the hydraulic oil hydraulic device according to claim 1.
The compound having a glycidyl group or an epoxy group is the formula (4).

The hydraulic oil for a hydraulic system according to claim 1, wherein R 6 is a saturated or unsaturated hydrocarbon group having 3 to 30 carbon atoms in the formula (4).
The content of at least one selected from the group consisting of the phosphite ester compound and the phosphate ester compound is at least one selected from the group consisting of the base oil and the phosphite ester compound and the phosphate ester compound. The hydraulic oil for a hydraulic device according to claim 1, which is 0.3% by mass or more and 5.0% by mass or less with respect to the total.
Equation (5)

(In the formula (5), R 7 and R 8 are each independently saturated or unsaturated hydrocarbon group having 8 or more and 24 or less carbon atoms), further comprising a secondary amide compound. The hydraulic oil for a hydraulic device according to 1.
The content of the secondary amide compound is 0.01 with respect to the total of the base oil, at least one selected from the group consisting of the phosphite ester compound and the phosphate ester compound, and the secondary amide compound. The hydraulic oil for a hydraulic device according to claim 6, which is equal to or more than% by mass and not more than 2.0% by mass.
The hydraulic oil for a hydraulic system according to claim 1, wherein at least one selected from the group consisting of the phosphite ester compound and the phosphoric acid ester compound is diorail hydrogen phosphite.
The hydraulic oil for a hydraulic system according to claim 1, wherein the primary amine compound is oleylamine.
The hydraulic oil for a hydraulic system according to claim 1, wherein the compound having a glycidyl group or an epoxy group is octylglycidyl ether.
A hydraulic device including the hydraulic oil for the hydraulic device according to claim 1.
Cylinder and
A piston rod that can move relative to the cylinder,
An oil seal fixed to the cylinder and sliding with the piston rod,
The hydraulic system according to claim 11, further comprising the hydraulic oil for the hydraulic system according to claim 1, which is injected into the cylinder.
The hydraulic device according to claim 12, wherein at least a part of the surface of the piston rod is chrome-plated.
The hydraulic device according to claim 12, which is a shock absorber for automobiles.