JPH1129783A - Hydraulic fluid composition for shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a hydraulic oil compsn. for a snubber which possesses good abrasion resistance and friction properties (low coefficient of friction) and is excellent in prevention of corrosion or dissolution of metallic materials, such as copper and iron. SOLUTION: This hydraulic oil compsn. for a snubber comprises: a lube base oil; and, incorporated into the lube base oil, based on the total wt. of the compsn., 0.01 to 2.0 wt.% benzotriazole or deriv. thereof (A) and 0.001 to 2.0 wt.% thiadiazole deriv. (B), the wt. ratio of the component (A) to the component (B) being (2.5:1) to (10:1).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a hydraulic oil composition for a shock absorber. More specifically, it has good wear resistance and low coefficient of friction, especially for corrosion and corrosion of metallic materials such as copper and iron.
The present invention relates to a hydraulic fluid composition for a shock absorber excellent in dissolution prevention properties.

[0002]

2. Description of the Related Art In general, hydraulic shock absorbers (buffers) are used to absorb vibrations in a vehicle body suspension (suspension device) in an automobile.
The structure of the shock absorber is basically a cylindrical structure using the flow resistance of oil, and usually a hydraulic piston having a small hole in a piston is used. In the shock absorber having this cylindrical structure, oil passes through the hole according to the up and down of the piston, and the resistance at that time is proportional to the speed of the piston. For this reason, a guide bush, which also serves as a guide, is provided in the sliding portion between the cylinder and the piston rod to prevent mutual wear, and the whole is sealed to prevent oil leakage. Various types of shock absorbers, such as a double-tube type and a gas-filled type, are known in addition to the above-mentioned cylindrical structure.

In the case of the shock absorber having such a structure, a large number of combined frictions occur between the piston rod and the guide bush, between the piston rod and the seal, and between the piston and the cylinder, as described above. In addition, in the case of automobiles, it is necessary to reduce the vibration to the automobile under severe driving conditions to ensure ride comfort and steering stability, and therefore, for hydraulic oil used for shock absorbers,
There is a demand for good wear resistance and durability, and good friction characteristics.

In automobiles, similar shock absorbers are also used in engine support devices, bumper shock absorbers, door checkers, and the like. Also, in an aircraft, a hydraulic shock absorber for absorbing impact during takeoff and landing is arranged. The same performance as described above is required for the hydraulic oil used in these shock absorbers.

[0005] Conventionally, as a hydraulic fluid for a shock absorber having good wear resistance, durability and friction characteristics, zinc dithiophosphate (Zn-DTP) in a lubricating base oil has been used as an oily agent such as a long-chain fatty acid. Hydraulic hydraulic oil composition for buffer added together with detergent dispersant (Japanese Patent Application Laid-Open No. 55-165996), and fluid composition for buffer containing lubricant base oil containing boron-containing detergent dispersant and phosphate ester JP-A-2-44879), a hydraulic oil composition for a buffer containing a phosphate ester or the like and an alkanolamine in a lubricating base oil (Japanese Patent Application Laid-Open No. HEI 5 (1993) -205).
JP-A-255683), a hydraulic fluid composition for a shock absorber in which a phosphate ester or the like and an aliphatic polyamine are blended in a lubricating base oil (JP-A-7-224293), and a phosphate ester or the like in the lubricating base oil. Hydraulic hydraulic oil composition for a shock absorber containing an aliphatic polyamine and an aliphatic monoamine
No. 258,673). Also,
Although different from the hydraulic fluid for shock absorbers, a fluid composition for active suspension in which a phosphite, an aliphatic amine, a thiadiazole and a benzotriazole are blended with a lubricating base oil has been proposed (Japanese Patent Application Laid-Open No. 8-165483).

However, in the case of shock absorbers, especially automobile shock absorbers, a guide bush mounted inside thereof is generally made of a copper alloy coated with Teflon, and the back metal is also plated with copper. In many cases, a hydraulic oil for a shock absorber having high stability against copper is desired from the viewpoint of corrosion, dissolution, and the like. On the other hand, it is also required that iron, which is a material of main components such as an outer cylinder, an inner cylinder, a cylinder, a piston, and a piston rod, of the shock absorber does not cause problems such as corrosion and melting. .

However, in the conventionally proposed hydraulic fluid for a shock absorber, for example, a hydraulic fluid in which Zn-DTP and an oil agent such as a long chain fatty acid are added, the oil agent such as a long chain fatty acid used Have the disadvantage of corroding the bearing material and promoting wear. In addition, hydraulic fluids for shock absorbers using highly polar additives such as phosphate esters react with copper to damage the guide bush, or react with iron in the presence of moisture to reduce the performance of the hydraulic fluid itself. This has the disadvantage that the performance against corrosion or dissolution of copper or iron is not always sufficient, for example, due to problems such as impairment.

For this reason, the hydraulic fluid for a shock absorber has good wear resistance and friction characteristics (low friction coefficient),
Further, there is a strong demand for the development of a hydraulic oil for a shock absorber excellent in corrosion and dissolution prevention of metal materials such as copper and iron.

[0009]

SUMMARY OF THE INVENTION In view of the above-mentioned developments, it is an object of the present invention to provide good wear resistance and friction characteristics (low friction coefficient), and furthermore, to improve the performance of metallic materials such as copper and iron. An object of the present invention is to provide a hydraulic oil composition for a shock absorber having excellent corrosion and dissolution prevention properties.

The present inventors have conducted intensive studies in order to solve the above-mentioned problems of the prior art, and as a result, a specific amount of each of benzotriazole or a derivative thereof and a thiadiazole derivative has been blended into a lubricating base oil, and By setting the blending ratio of benzotriazole or its derivative and thiadiazole derivative within a specific range, it has good abrasion resistance and friction characteristics (low friction coefficient) required as a hydraulic fluid for shock absorbers, and furthermore, copper and iron It has been found that a hydraulic oil composition for a shock absorber excellent in corrosion and dissolution prevention of metal materials such as the above can be obtained. The present invention has been completed based on these findings.

[0011]

According to the present invention, (A) 0.01 to 2.0% by weight, based on the total weight of the composition, of benzotriazole and (B) thiadiazole are added to a lubricating base oil. Derivatives 0.001 to 2.0% by weight are blended, respectively, and the blending ratio [(A) / (B)] of the components (A) and (B) is 2.5 to 10 (weight ratio). A hydraulic fluid composition for a shock absorber is provided.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a hydraulic oil composition for a shock absorber having good wear resistance and friction characteristics (low friction coefficient) and excellent corrosion and dissolution prevention of metallic materials such as copper and iron. It relates to things, but as a preferred embodiment,
The following are included:

[0013] Based on the total weight of the composition,
(A) Benzotriazole or a derivative thereof 0.01 to
2.0% by weight and (B) thiadiazole derivative 0.00
1 to 2.0% by weight, and the mixing ratio of the component (A) to the component (B) [(A) / (B)] is 2.5.
A hydraulic fluid composition for a shock absorber characterized by being in the range of from 5 to 5 (weight ratio). (A) benzotriazole or a derivative thereof in an amount of 0.01 to 2.0% by weight based on the total weight of the composition in the lubricating base oil;
(B) thiadiazole derivative 0.001 to 2.0% by weight
And (C) at least one compound selected from the group consisting of phosphate esters, phosphite esters and phosphate amine salts in an amount of 0.1 to 5.0% by weight, respectively. (B) The hydraulic fluid composition for a shock absorber, wherein the mixing ratio [(A) / (B)] with the component is in the range of 2.5 to 10 (weight ratio). The compounding ratio of the component (A) and the component (B) [(A) /
(B)] is in the range of 2.5 to 5 (weight ratio). (A) The hydraulic fluid composition for a shock absorber according to any one of the above (1) to (4), wherein the amount of the component is 0.05 to 0.3% by weight. (B) The hydraulic fluid composition for a shock absorber according to any one of the above (1) to (4), wherein the amount of the component (B) is 0.01 to 0.05% by weight. (C) The hydraulic fluid composition for a shock absorber according to the above, wherein the compounding amount of the component is 0.2 to 3.0% by weight. The components (A), (B) and (C)
The components are blended in specific amounts, respectively, and the components (A) and (B)
The compounding ratio [(A) / (B)] of the components is in the range of 2.5 to 10 (weight ratio). , A viscosity index improver, a pour point depressant, a rust inhibitor, an antifoaming agent and at least one additive component selected from the group of additive components required for the hydraulic fluid composition for shock absorbers. Hydraulic fluid composition for shock absorber.

Hereinafter, the present invention will be described in detail. (1) Lubricating base oil The base oil of the hydraulic fluid composition for a shock absorber of the present invention is not particularly limited, and various conventionally known mineral oils and synthetic oils can be used. As a mineral oil, a solvent-refined raffinate obtained by treating a lubricating oil raw material derived from atmospheric or reduced pressure distillation of crude oil with an aromatic extraction solvent such as phenol, furfural and N-methylpyrrolidone, and hydrotreating the lubricating oil raw material A hydrotreated oil obtained by contacting with hydrogen under hydrotreating conditions in the presence of a catalyst for use, an isomerized oil obtained by contacting wax with hydrogen under isomeric conditions in the presence of a catalyst for isomerization, Alternatively, a lubricating oil fraction obtained by combining a solvent refining step, a hydrotreating step, an isomerization step and the like can be mentioned. In any of the production methods, the steps such as the dewaxing step, the hydrofinishing step, and the clay treatment step can be arbitrarily adopted by a conventional method.
Specific examples of mineral oils include, for example, light neutral oil,
Medium neutral oil, heavy neutral oil, bright stock and the like. Examples of the synthetic oil include poly-α-olefin (α-olefin oligomer), polybutene, alkylbenzene, polyol ester, dibasic acid ester, and silicone oil. These base oils can be used alone or in combination of two or more, and mineral oil and synthetic oil may be used in combination. The base oil has a kinematic viscosity at 100 ° C. of usually 1.0.
内²⁰ mm ² / s are used.
Those having a range of 5 to 15 mm ² / s are preferred.

(2) Benzotriazole or benzotriazole derivative (A) In the hydraulic fluid composition for a shock absorber of the present invention, the benzotriazole or benzotriazole derivative used as the component (A) has the following general formula [I] and It is represented by [II]. The general formula [I] is a benzotriazole or an alkylated benzotriazole, and the general formula [II] is a benzotriazole derivative. Specific examples of the benzotriazole derivative include, for example, REO manufactured by Ciba-Geigy.
MET39, REOMET42, REOMET SBT
75 and RC4901 manufactured by Line Hem Inc. Preferred examples thereof include benzotriazole, alkylated benzotriazole, and REOMET39 manufactured by Ciba-Geigy.

The amount of component (A) is 0.01 to 2.0% by weight, preferably 0.05 to 2.0% by weight, based on the total weight of the composition.
0.3% by weight. If the amount is too large, problems such as an increase in friction coefficient and frictional force and an increase in wear occur. On the other hand, if the amount is too small, the reaction between a phosphorus compound such as a phosphoric ester or a phosphite and copper cannot be prevented, and copper corrosion or copper dissolution occurs.

The general formula [I]

Embedded image (However, R ¹ is a hydrogen atom or a hydrocarbon group having 1 to 18 carbon atoms, and is preferably a saturated or unsaturated alkyl group having 1 to 4 as the hydrocarbon group.)

General formula [II]

Embedded image (However, R ¹ and R ² are a hydrogen atom or a hydrocarbon group having 1 to 18 carbon atoms.
18 saturated or unsaturated alkyl groups. )

(3) Thiadiazole derivative (B) In the hydraulic fluid composition for a shock absorber of the present invention, the thiadiazole derivative used as the component (B) is represented by the following general formula [III]. Specific examples of thiadiazole derivatives include, for example, 1,3,4-thiadiazole polysulfide, 2,5-bis (n-dodecyldithio) -1,
3,4-thiadiazole, 2,5-bis (octyldithio) -1,3,4-thiadiazole, 2,5-bis (N, N-diethyldithiocarbamyl) -1,3,4-
Thiadiazole and the like. Preferred specific examples thereof include 1,3,4-thiadiazole polysulfides.

Component (B) is added in an amount of 0.001 to 2.0% by weight, preferably 0.01 to 2.0% by weight, based on the total weight of the composition.
0.05% by weight. If the amount is too large, problems such as an increase in friction coefficient and friction force, an increase in wear, and corrosion occur. On the other hand, if the amount is too small, the reaction between a phosphorus compound such as a phosphoric ester or a phosphite and copper cannot be prevented, and copper corrosion or copper dissolution occurs.

Formula [III]

Embedded image (However, the X and Y groups are (S) _n -R ³ or a hydrogen atom, and may be the same or different. N is 0 to 7)
Is an integer. R ³ is a hydrocarbon group having 1 to 18 carbon atoms, and the hydrocarbon group is preferably a saturated or unsaturated alkyl group having 1 to 18 carbon atoms. In addition, the blending ratio of the benzotriazole or the derivative (BT) of the component (A) and the thiadiazole derivative (TD) of the component (B) is an essential condition of the present invention [(A) / (B),
[BT / TD] is in the range of 2.5 to 10 (weight ratio). The preferred range of the mixing ratio is 2.5 to
5 If the compounding ratio is too large or too small, problems such as an increase in the coefficient of friction and frictional force, an increase in abrasion, and corrosion will occur.

(4) Phosphate, Phosphite and Phosphate Amine Salts (C) In the present invention, by further blending the following component (C), a favorable hydraulic oil composition for a shock absorber can be obtained. It will be. Component (C) is at least one compound selected from the group consisting of phosphate esters, phosphite esters and phosphate amine salts. Examples of the phosphate and the phosphite include those represented by the following general formula.

O = P (OR ⁴ ) (OR ⁵ ) (OR ⁶ ) O = P (OH) (OR ⁴ ) (OR ⁵ ) O = P (OH) ₂ (OR ⁴ ) P (OR ⁴ ) (OR ⁵ ) (OR ⁶ ) P (OH) (OR ⁴ ) (OR ⁵ ) P (OH) ₂ (OR ⁴ ) (where R ⁴ , R ⁵ and R ^{6 each} have 4 or more carbon atoms, preferably 4 to 20 carbon atoms) And a saturated or unsaturated alkyl group, aryl group or alkyl-substituted aryl group, which may be the same or different.) Specific examples of the phosphate ester and the phosphite ester include dibutyl acid phosphate, -Ethylhexyl acid phosphate, lauryl acid phosphate, oleyl acid phosphate, dioleyl acid phosphate, dibutyl hydrogen phosphite,
Dilaryl hydrogen phosphite, distearyl hydrogen phosphite, dioleyl hydrogen phosphite, diphenyl hydrogen phosphite and the like can be mentioned.

The phosphate amine salt used in the present invention is a reaction product of a phosphate or phosphite with an amine compound. Examples of the amine compound include a primary or secondary amine comprising a saturated or unsaturated alkyl group having 10 to 20 carbon atoms. Specific examples include oleylamine salt of di-2-ethylhexyl acid phosphate [reaction product of (C ₈ H ₁₇ O) ₂ P (OH) O and (C ₁₈ H ₃₅ ) NH ₂ ], oleylamine of n-butyl acid phosphate Salts, 2-ethylhexylamine salt of oleyl acid phosphate, and the like.

These phosphate compounds can be used alone or in combination of two or more. The mixing ratio of the phosphate compound is
Usually 0.1 to 5.0% by weight, preferably 0.2 to 3.0% by weight, more preferably 0.3 to 3.0% by weight based on the total amount of the composition.
2.0% by weight.

Within the range of the compounding ratio, 0.01 to 2.0% by weight of the benzotriazole or benzotriazole derivative (BT) of the component (A) used in the present invention;
(B) thiadiazole derivative (TD) of component 0.001
２．０2.0% by weight, and the mixing ratio [(A) / (B), BT / TD] of component (A) (BT) and component (B) (TD) is 2. When it is in the specific range of 5 to 10 (weight ratio), it has good wear resistance and friction characteristics, and can exhibit excellent corrosion and dissolution prevention of metal materials such as copper and iron.

(5) Other Additives Other additives may be added to the hydraulic fluid composition for a shock absorber of the present invention, if necessary, such as a friction modifier and an antiwear agent, as long as the object of the present invention is not impaired. In addition, an antioxidant, an ashless detergent / dispersant, a metal detergent, a viscosity index improver, a pour point depressant, a rust inhibitor, an antifoaming agent, and the like can be appropriately added.

Examples of the friction modifier include fatty acids (such as oleic acid and stearic acid), higher alcohols (such as oleyl alcohol), fatty acid esters, oils and fats, polyhydric alcohol esters, sorbitan esters, and aliphatic amines. These are usually from 0.05 to 3.0.
Used in percentages by weight.

Examples of the antiwear agent include metal dithiophosphates (Zn, Pb, Sb, Mo, etc.), metal dithiocarbamates (Zn, Mo, etc.) metal naphthenates (Pb, etc.), and fatty acid metal salts (Pb, etc.) ), Sulfurized fats and oils, sulfur compounds, boron compounds, and the like.
Usually, it is used in a proportion of 0.05 to 3.0% by weight.

Examples of the antioxidant include amine antioxidants such as alkylated diphenylamine, phenyl-α-naphthylamine and alkylated phenyl-α-naphthylamine, 2,6-di-t-butylphenol, 4,4′-methylenebis -Phenolic antioxidants such as-(2,6-ditert-butylphenol); phosphorus-based antioxidants such as phosphite; and sulfur-based antioxidants such as dilauryl-3,3'-thiodipropionate. Can be
These are usually used at a ratio of 0.05 to 2.0% by weight.

Examples of the ashless detergent / dispersant include succinimide-based, succinic amide-based, benzylamine-based and succinate-based detergents, and a boron-containing ashless detergent-dispersant can also be used. These are usually used at a ratio of 0.5 to 7.0% by weight.

Examples of the metal detergent include Ca-sulfonate, Mg-sulfonate, Ba-sulfonate and Ca-sulfonate.
Phenate, Mg-phenate, Ba-phenate, C
There are a-salicylate, Mg-salicylate, Ba-salicylate and the like, which are usually used at a ratio of 0.1 to 5.0% by weight.

Examples of the viscosity index improver include polymethacrylates, polyisobutylenes, ethylene-propylene copolymers, polyalkylstyrenes, styrene-butadiene hydrogenated copolymers, and styrene-maleic anhydride copolymers. And usually 0.5 to 35% by weight
Used in proportions.

Examples of the rust preventive include carboxylic acid, carboxylate, sulfonate, amine, alkenylsuccinic acid and partial esters thereof, and the like can be appropriately added.

Examples of the antifoaming agent include dimethylpolysiloxane and polyacrylate, which can be added as appropriate.

[0036]

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. The methods for measuring various physical properties of copper solubility, iron solubility, friction coefficient, and wear resistance in the examples are as follows.

(1) Solubility of Copper 200 ml of sample oil was placed in a 500 ml beaker, and two copper plates (25 × 50 mm) were immersed in the beaker and allowed to stand in a 100 ° C. constant temperature bath. After 200 hours, determine the amount of copper dissolved in the sample oil by J
It was measured by the ICP method of IS K0116. It is considered that a copper content of the sample oil of 20 ppm or less is desirable as an evaluation standard of copper solubility.

(2) Iron solubility 200 ml of sample oil was placed in a 500 ml beaker,
Six steel plates (26 × 121.1 mm) to be used as a catalyst in the SK2514 lubricating oil oxidation stability test method were immersed,
After standing at room temperature for 50 days, the amount of iron dissolved in
It was measured by the ICP method of IS K0116. It is considered that the iron content in the sample oil is preferably 20 ppm or less as an evaluation standard of iron solubility.

(3) Coefficient of friction Using a Bowden tester, the coefficient of friction of the sample oil was measured using a nitrile rubber (A217) plate and chrome plated pins. The test conditions are room temperature, a load of 3 kgf, a sliding speed of 3.3 mm / s, and a sliding distance of 20 mm. It is considered that a friction coefficient of the sample oil of 0.10 or less is desirable as an evaluation standard.

(4) Antiwear Property The wear resistance of the sample oil was evaluated by a shell-type four-ball test method according to ASTM D4172. The test conditions were a temperature of 120 ° C., a test time of 30 minutes, and a rotation speed of 1800 r.
pm and a load of 60 kgf. It is considered that a wear scar diameter of 0.70 mm or less is desirable as a criterion for evaluating the wear resistance of the sample oil.

Example A highly refined mineral oil having a kinematic viscosity at 100 ° C. of 2.6 mm ² / s was used as a lubricating base oil, and each of the components shown in Tables 1 and 2 was added to prepare each test oil. did. The components used are as follows.

(1) Component (A), BT: benzotriazole derivative (2) Component (B), TD-1: 2,5-bis (octyldithio) -1,3,4-thiadiazole TD-2: 2 , 5-Bis (nonyldithio) -1,3,4
- thiadiazole TD-3: 2,5-dimercapto-1,3,4-derivatives of thiadiazole, in the general formula [III], the group X (S) is ₁ ~ ₆ -R ^3, R ³ is the number of carbon atoms 1 to 24 alkyl or aralkyl groups. The group Y is a hydrogen atom. (3) Phosphate: oleyl acid phosphate (4) Phosphite: dioleyl hydrogen phosphite (5) Other additives: alkenyl succinimide
25% by weight, 0.3% by weight of phenolic antioxidant,
1.5% by weight of a polymethacrylate-based viscosity index improver,
0.5% by weight of sorbitan ester, 5ppm of silicone defoamer The mixing ratio of each additive component in Tables 1 and 2 is% by weight based on the total amount of the composition, and the balance is base oil. Copper solubility, iron solubility, friction coefficient, and wear resistance of the obtained hydraulic fluid composition for a shock absorber were measured and evaluated. The results are shown in Tables 1 and 2.

[0043]

[Table 1]

[0044]

[Table 2]

Examples 1 to 8 In Example 1, the content of the benzotriazole derivative (BT) was 0.15% by weight, and the content of the thiadiazole derivative (TD) was 0 as the hydraulic fluid composition for a shock absorber. 0.06% by weight, BT / TD compounding ratio of 2.5, phosphate compounding amount of 0.1% by weight, phosphite compounding amount of 1.1% by weight and compounding amounts of other additives Is 2.55% by weight. Similarly, in Examples 2 to 8, hydraulic fluid compositions for shock absorbers were prepared at the ratios shown in Table 1. In each of Examples 1 to 8, the components (A) and (B) are mixed in a specific amount, and the ratio of the component (A) to the component (B) is in a specific range of 2.5 to 10. as a result,
The copper solubility and the iron solubility were good in Examples 1 to 8, and neither copper nor iron was detected in the test oil, or even if it was detected, it was as small as 5 ppm and was 20 ppm or less. The coefficients of friction of Examples 1 to 8 were good, and the values were all 0.09 to
0.10, which was 0.10 or less. The anti-wear property is 0.58 to 0.60 mm for both wear marks and 0.70
mm or less. In any of the examples, it was found that high quality hydraulic oil for shock absorbers could be obtained.

Comparative Examples 1 to 7 Lubricating base oil components and various additive components shown in Table 2 were blended in the proportions shown in the same table to prepare hydraulic working oil compositions for shock absorbers. Comparative Example 1 is a case where neither the component (A) nor the component (B) is blended. As a result, although the coefficient of friction and the anti-wear property are good, copper and iron are detected in the test oil, Copper solubility and iron solubility are very poor. Comparative Examples 2 and 3 are cases in which either the component (A) or the component (B) is not blended. As a result, as in Comparative Example 1, although the friction coefficient and abrasion resistance are good, the test oil There is detection of copper and iron, and copper solubility and iron solubility are very poor. In Comparative Example 4, the components (A) and (B) were mixed in specific amounts, but the ratio (BT / TD) of the components (A) and (B) was out of the specific range of 2.5 to 10 (125). )
Is the case. As a result, poor results were obtained in all four performances of copper solubility, iron solubility, friction coefficient, and wear prevention. Comparative Example 5 also contains specific amounts of the components (A) and (B) as in Comparative Example 4, but the ratio (BT / TD) of the components (A) and (B) is 2.5 to 10. Outside the specified range (0.
1). In the same manner as in Comparative Example 4, poor results were obtained in all of the four properties of copper solubility, iron solubility, friction coefficient, and abrasion prevention. Particularly, copper solubility is poor. Comparative Example 6
Means that the ratio (BT / TD) of component (A) to component (B) is 2.
It is within the specific range of 5 to 10 (2.5), but the amount of the component (A) and the component (B) is very small and is lower than the lower limit. Although the coefficient of friction and wear resistance are good, the solubility of copper and iron is poor. Comparative Example 7 contains specific amounts of the components (A) and (B) as in Comparative Examples 4 and 5.
The ratio (BT / TD) of the component (A) to the component (B) is 2.5 to
This is the case where the value is out of the specific range of 10 (1). Copper solubility,
Although the coefficient of friction and wear resistance are good, iron solubility is poor.

When the components (A) and (B) are used in combination and are mixed in a specific amount, and the ratio of the component (A) to the component (B) is within a specific range of 2.5 to 10, the high A high quality hydraulic fluid for shock absorber is obtained. That is, it has been found that the combination of the components (A) and (B) in a limited addition range is effective not only in preventing corrosion and dissolution of copper but also in preventing corrosion and dissolution of iron. , The resulting friction coefficient, friction force,
It is presumed that excellent hydraulic fluid far superior to the conventional hydraulic fluid can be obtained without impairing the main performance such as anti-wear properties for the following reasons.

The component (A), benzotriazole or a derivative thereof, protects most of the metal surface but cannot completely protect it.
The thiadiazole derivative as the component (B) works effectively. In this case, for protection of the metal surface, these (A)
Since the molecular structure of the component and the component (B) is involved, the effect is greatest when added in a certain ratio. Therefore, since the component (A) and the component (B) protect the metal surface with the minimum necessary amount of addition, adverse effects on other additives are minimized, and as a result, all the main performances can be satisfied. It is.

[0049]

The hydraulic fluid composition for a shock absorber according to the present invention comprises:
The aforementioned components (A) and (B) are blended in specific amounts with the lubricating base oil, and the blending ratio of the components (A) and (B) [(A) / (B)] is 2.5 to 10 (weight ratio), having good wear resistance and friction characteristics (low friction coefficient) required as hydraulic fluid for shock absorbers,
Has excellent performance in preventing corrosion and dissolution of metal materials such as copper and iron.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C10N 30:12 30:14 40:08 (72) Inventor Hiroshi Ohashi 1-3-1 Nishitsurugaoka, Oimachi, Iruma-gun, Saitama Inside the Tonen Research Laboratory (72) Naoto Otsuka Inventor 1-3-1 Nishitsurugaoka, Oi-machi, Iruma-gun, Saitama Prefecture Inside the Tonen Research Laboratory (72) Koji Takemitsu Nishi-Tsurugaoka, Oi-machi, Iruma-gun, Saitama 1-3-1 in Tonen Co., Ltd. (72) Inventor Yoshitaka Nakatani 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Koichi Kurono 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto Inside the car company

Claims (1)

[Claims] Claims 1. A lubricating base oil comprising, based on the total weight of a composition,
(A) Benzotriazole or a derivative thereof 0.01 to
2.0% by weight and (B) thiadiazole derivative 0.00
1 to 2.0% by weight, and the mixing ratio of the component (A) to the component (B) [(A) / (B)] is 2.5.
A hydraulic oil composition for a shock absorber characterized by being in the range of 10 to 10 (weight ratio).