JP2002180078A - Lubricating oil for sintered metal bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lubricating oil for sintered metal bearing having excellent abrasion resistance and maintaining a low coefficient of friction for a long period of time. SOLUTION: This lubricating oil for a sintered metal bearing is obtained by mixing a base oil with one or more kinds selected from (A) 0.05-5.0 mass % of an acid phosphate, (B) 0.05-5.0 mass % of an amine salt of acid phosphate and (C) 0.05-5.0 mass % of a phosphite. The lubricating oil may further contain one or more kinds selected from (D) 0.05-2.0 mass % of an alkylated diphenylamine, (E) 0.05-2.0 mass % of an alkylated phenyl-α-naphthylamine and (F) 0.05-2.0 mass % of a hindered phenol and further one or more kinds selected from (G) 0.001-0.05 mass % of benzotriazole and 0.001-0.05 mass % of its derivative and (H) 0.01-0.3 mass % an alkylsuccinic acid derivative.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricating oil for a sintered metal bearing, and more particularly to a lubricating oil for a sintered metal bearing having excellent wear resistance and a friction reducing effect.

[0002]

2. Description of the Related Art Conventionally, carbon steel,
Nickel chrome steel, nickel chrome molybdenum steel, manganese steel, manganese chrome steel, aluminum chrome molybdenum steel, high carbon chrome steel, stainless steel, etc .; copper, brass, bronze, phosphor bronze, high strength brass, aluminum bronze, lead bronze, phosphorus Copper, magnesium copper, beryllium copper, etc .; sintered metals such as pure iron, iron-copper, iron-carbon, iron-
Carbon-copper, iron-carbon-copper-nickel, iron-carbon (copper infiltration), iron-nickel, iron-carbon-nickel, austenitic stainless steel, martensitic stainless steel, bronze, etc. Various lubricating oils have been used for lubricating bearings using these, depending on the application.

[0003]

By the way, despite the fact that selecting a lubricating oil suitable for the metal material used for the bearing improves the life of the bearing, the complexity of the selecting operation makes the general-purpose bearing oil difficult. Sometimes used. Also, bearing oils, especially lubricating oils used for sintered metal bearings, lubricate bearings with a very thin oil film thickness, which locally increases the temperature and shortens the oil life. And
One of the important performances is that heat due to friction is hardly generated. In particular, bearings used for precision machinery are often used in a maintenance-free manner due to their characteristics, and are required to maintain a friction reducing effect for a long period of time.

The present invention is a lubricating oil used for a sintered metal bearing in the above-mentioned circumstances, but can be used irrespective of the type of the sintered metal, and has a wear resistance and a friction reducing effect. It is an object of the present invention to provide a lubricating oil for a sintered metal bearing which has excellent characteristics and can maintain these characteristics for a long period of time.

[0005]

The lubricating oil for sintered metal bearings of the present invention uses mineral oil or synthetic oil as a base oil, and the base oil comprises [1] (A) acid. 0.05 to 5.0% by mass of phosphate, 0.05 to 5.0% by mass of (B) amine salt of acid phosphate, and 0.05 to 5.0% by mass of (C) phosphite In addition to [2] [1], (D) alkylated diphenylamine 0.05 to 2.0.
0% by mass, (E) 0.05 to 2.0% by mass of alkylated phenyl-α-naphthylamine, and (F) 0.05 to 2.0% by mass of hindered phenols. And (3) [1] or [2], and (G) at least one selected from 0.001 to 0.05% by mass of benzotriazole or 0.001 to 0.05% by mass of a derivative thereof; (H) The alkyl succinic acid derivative may contain 0.01 to 0.3% by mass. Sintered metal bearings have the property of being soft and susceptible to corrosion due to their material. For this reason, it is extremely difficult to select an anti-wear agent for the lubricating oil used for the sintered metal bearing. (A) the acid phosphate of the above [1],
By using (B) an amine salt of acid phosphate and (C) phosphite, the present inventors succeeded in obtaining abrasion characteristics, particularly excellent friction reducing effect.

The base oil used for the lubricating oil for sintered metal bearings of the present invention is mineral oil or synthetic oil. The kind of the mineral oil or the synthetic oil is not particularly limited, but the kinematic viscosity at 40 ° C. is 3 to 500 mm ² / s, preferably 4 to 250 mm ² / s.
mm ² / s, more preferably 5 to 150 mm ² / s, particularly preferably 6~100mm ² / s. If the kinematic viscosity at 40 ° C. is less than 3 mm ² / s, an appropriate oil film may not be obtained, and if it exceeds 500 mm ² / s, the resistance torque when the shaft rotates becomes excessive.

The mineral oil having the above kinematic viscosity includes paraffinic mineral oil, naphthenic mineral oil, and intermediate mineral oil obtained by refining such as solvent refining and hydrorefining. Synthetic oils include hydrocarbon synthetic oils; monoesters, diesters, polyol esters (trimethylolpropane, pentaerythritol, dipentaerythritol, neopentyldiol ester, complex ester), polyglycol esters, glycerin esters, aromatic esters, etc. Ester oils; ether oils such as alkylated diphenyl ethers, alkylated triphenyl ethers, alkylated tetraphenyl ethers, and alkylated polyphenyl ethers; various silicone oils; and various fluorine oils. As a specific example,
Examples of the hydrocarbon synthetic oil include poly-α-olefin, polybutene, ethylene-α-olefin oligomer, and the like. Monoesters include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid,
Ricinoleic acid, linoleic acid, linolenic acid, arachidonic acid, icosapentaenoic acid, erucic acid, docosahexaenoic acid, lignoceric acid, and methanol, ethanol,
Monoesters composed of monohydric alcohols such as propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol and the like can be mentioned. Diesters include malonic acid, methyl malonic acid, succinic acid,
Methyl succinic acid, dimethyl malonic acid, ethyl malonic acid,
Glutanic acid, adipic acid, dimethylsuccinic acid, pimelic acid, tetramethylsuccinic acid, suberic acid, azelaic acid, sebacic acid, brasilic acid, etc., methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol And diesters composed of dibasic acids of the same or different monohydric alcohols such as decanol, undecanol, dodecanol, dodecanol, tridecanol, tetradecanol and pentadecanol. As polyol esters, trimethylolethane, trimethylolpropane, pentaerythritol and caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, ricinoleic acid, linoleic acid, linolenic acid, Polyol esters composed of arachidonic acid, icosapentaenoic acid, erucic acid, docosahexaenoic acid, and lignoceric acid. Polyglycol esters include polyglycol, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, ricinoleic acid, linoleic acid, linolenic acid, arachidonic acid, icosapentaenoic acid, elca acid,
Glycol esters composed of docosahexaenoic acid and lignoceric acid. Examples of glycerin esters include mono-fatty acid glycerin, di-fatty acid glycerin, and tri-fatty acid glycerin, and the fatty acids include caprylic acid,
Capric, lauric, myristic, palmitic, palmitoleic, stearic, oleic, ricinoleic, linoleic, linolenic, arachidonic,
Icosapentaenoic acid, erucic acid, docosahexaenoic acid,
Lignoceric acid. The polyphenyl ether may have no alkyl group or may have a linear or branched alkyl group. Specific examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n
-Pentyl, isopentyl, neopentyl, tert-
Pentyl, 2-methylbutyl, n-hexyl, isohexyl, 3-methylpentyl, ethylbutyl, n-heptyl, 2-methylhexyl, n-octyl, 2-ethylhexyl, 3-methylheptyl, n-nonyl, methyloctyl, ethylheptyl n-decyl, n-undecyl,
n-dodecyl, n-tetradecyl and the like. The above base oils may be used alone, or two or more kinds may be used in combination, or a mineral oil and a synthetic oil may be used in combination.

[0008] The acid phosphate of the component (A) blended in the above base oil has a structure represented by the following formula 1.

[0009]

Formula 1

In the above formula 1, R1 represents a hydrocarbon group having 4 or more carbon atoms, and a is 1 or 2. Specific examples of R1 include a linear or branched saturated or unsaturated aliphatic hydrocarbon group having 4 to 20 carbon atoms, that is, an alkyl group or an alkenyl group, an aromatic hydrocarbon group having 4 to 20 carbon atoms, And cycloalkyl groups. If the number of carbon atoms is less than 4 or more than 20, the intended performance (extreme pressure performance or low friction coefficient) may not be obtained. A preferred range of carbon number is 6-18, and a more preferred range is 8-12. Specific examples of the acid phosphate of the component (A) include, for example, 2-ethylhexyl acid phosphate, isodecyl acid phosphate, lauryl acid phosphate, tridecyl acid phosphate, stearyl acid phosphate, isostearyl acid phosphate, oleyl acid phosphate and diyl acid phosphate. (2-ethylhexyl) phosphate and the like. These acid phosphates may be used alone or in combination of two or more.

The mixing ratio of the component (A) is 0.05 to 5% by mass, preferably 0.1 to 3% by mass, more preferably 0.3 to 2% by mass, and particularly preferably 0.5 to 1. 5% by mass. If the compounding ratio is less than 0.05% by mass, it is difficult to realize sufficient extreme pressure performance and a low friction coefficient, and even if it exceeds 5% by mass, the effect is saturated, which is economically disadvantageous.

The amine salt of the acid phosphate of the component (B) may be an alkylamine formed by neutralizing the acid phosphate of the component (A), and examples thereof include an alkylamine having a structure represented by the following formula 2. .

[0013]

Formula 2

In the above formula 2, R2, R3 and R4 are monovalent hydrocarbon groups or hydrogen atoms, at least one of which is a hydrocarbon group. Specific examples of such alkylamines include dibutylamine, octylamine, dioctylamine, laurylamine, dilaurylamine, oleylamine, coconutamine, tallowamine, and the like.
The above amine salts may be used alone or in combination of two or more.

The compounding ratio of the amine salt component of the acid phosphate (B) is 0.05 to 5% by mass,
Preferably 0.1 to 3% by mass, more preferably 0.3 to 3% by mass.
It is 2% by mass, particularly preferably 0.5 to 1.5% by mass. If the compounding ratio is less than 0.05% by mass, it is difficult to realize sufficient extreme pressure performance and a low friction coefficient, and if it exceeds 5% by mass, the effect is saturated, which is economically disadvantageous.

The phosphite of the component (C) has a structure represented by the following formula 3.

[0017]

Formula 3

In the above formula 3, R5 is a linear or branched alkyl group having 1 to 20, preferably 8 to 18 carbon atoms. Specific examples of R5 include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, ter
t-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, 2-methylbutyl, n-hexyl, isohexyl, 3-methylpentyl, ethylbutyl, n-heptyl, 2-methylhexyl, n-octyl, isooctyl, tert- Octyl, 2-ethylhexyl, 3-methylheptyl, n-nonyl, isononyl, 1-methyloctyl, ethylheptyl, n-decyl, 1-methylnonyl, n-undecyl, 1,1-dimethylnonyl, n-dodecyl, isododecyl, n-tridecyl, isotridecyl, n-tetradecyl, isotetradecyl, n-pentadecyl, isopentadecyl, n-hexadecyl, isohexadecyl, n-heptadecyl, isoheptadecyl, n-octadecyl, isooctadecyl, n-nonadecyl, iso Nadeshiru and the like.

Specific examples of the phosphite include tris (2-ethylhexyl-3-mercaptopropionate) phosphite, triphenyl phosphite, trioctadecyl phosphite, tristearyl phosphite, triisooctyl phosphite, and tris ( Nonalkylphenyl) phosphite, tricresylphosphite, diphenylisodecylphosphite and the like; trialkyl phosphites; dialkyl phosphites; monoalkyl phosphites. These phosphites may be used alone or in combination of two or more.

The compounding ratio of the phosphite as the component (C) is 0.05 to 5% by mass, preferably 0.1 to 3% by mass, more preferably 0.3 to 2% by mass, and particularly preferably 0.5 to 2% by mass. １．５1.5% by mass. If the compounding ratio is less than 0.05% by mass, it is difficult to realize sufficient extreme pressure performance and a low friction coefficient, and if it exceeds 5% by mass, the effect is saturated, which is economically disadvantageous.

The alkylated diphenylamine of the component (D) has a structure represented by the following formula 4.

[0022]

Formula 4

In the above formula 4, R6 and R7 may be the same or different and each represent a hydrogen atom or a carbon atom having 1 to 16, preferably 3 carbon atoms.
To 9 straight-chain or branched-chain alkyl groups, more preferably a hydrogen atom or a straight-chain or branched-chain alkyl group having 4 or 8 carbon atoms. If the alkyl group has more than 16 carbon atoms, the solubility in oil may decrease. Specific examples of the linear or branched alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, and 2-methylbutyl N-hexyl, isohexyl, 3-methylpentyl, ethylbutyl, n-heptyl, 2-methylhexyl, n-octyl, 2-ethylhexyl, 3-methylheptyl, n-nonyl, methyloctyl, ethylheptyl, n-decyl, n -Undecyl, n-dodecyl, n-
And tetradecyl. Preferable specific examples of the alkylated diphenylamine include diphenylamine, butyldiphenylamine, octyldiphenylamine, dibutyldiphenylamine, octylbutyldiphenylamine, and dioctyldiphenylamine.
These alkylated diphenylamines may be used alone or in combination of two or more.

The proportion of the alkylated diphenylamine of the component (D) is 0.05 to 2.0% by mass, preferably 0.1 to 1.5% by mass, more preferably 0.1 to 1.0% by mass.
% By mass. If the compounding ratio is less than 0.05% by mass, a sufficient antioxidant ability may not be obtained, and if it exceeds 2.0% by mass, the effect is saturated, and it is economically disadvantageous.

The alkylated phenyl-α-naphthylamine of the component (E) has a structure represented by the following formula 5.

[0026]

Formula 5

In the above formula 5, R8 is a linear or branched alkyl group having 1 to 16, preferably 4 to 8 carbon atoms.
Specific examples of R8 include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert.
-Butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, 2-methylbutyl, n-hexyl, isohexyl, 3-methylpentyl, ethylbutyl, n-heptyl, 2-methylhexyl, n-octyl, isooctyl, tert-octyl , 2-ethylhexyl, 3-methylheptyl, n-nonyl, isononyl, 1-methyloctyl, ethylheptyl, n-decyl, 1-methylnonyl, n-undecyl, 1,1-dimethylnonyl, n-dodecyl, n-tetradecyl And the like. Specific examples of the alkylated phenyl-α-naphthylamine include n-pentylated phenyl-α-naphthylamine, 2-methylbutylated phenyl-α-naphthylamine, 2-ethylhexylated phenyl-α-naphthylamine, and n-octylated phenyl-α. -Naphthylamine, n-nonylated phenyl-α-naphthylamine, 1-
Methyloctylated phenyl-α-naphthylamine, n-
Examples include undecylated phenyl-α-naphthylamine and n-dodecylated phenyl-α-naphthylamine. These alkylated phenyl-α-naphthylamines may be used alone or in combination of two or more.

The mixing ratio of the alkylated phenyl-α-naphthylamine of the component (E) is 0.05 to 2.0% by mass,
Preferably 0.1 to 1.5% by mass, more preferably 0.1 to 1.5% by mass.
1 to 1.0% by mass. If the amount is less than 0.05% by mass, a sufficient antioxidant ability may not be obtained, and if the amount exceeds 2.0% by mass, the effect is saturated, which is economically disadvantageous.

The hindered phenols of the component (F)
It has a structure represented by the following formulas 6 to 8.

[0030]

Formula 6 Equation 7 Equation 8

R9, R10, R1 in the above formulas 6 to 8
2, R13 may be the same or different and are a hydrogen atom or a linear or branched alkyl group having 1 to 12 carbon atoms, preferably a hydrogen atom or a linear or branched chain having 4 to 8 carbon atoms. Is an alkyl group. R11 has 1 to 1 carbon atoms
5, preferably 1-4 methylene groups. R14, R
15 may be the same or different and is a hydrogen atom or a linear or branched alkyl group having 1 to 12 carbon atoms, preferably a hydrogen atom or a linear or branched alkyl group having 4 to 8 carbon atoms. Group. n is 1 to 5, preferably 1 to
4 is an integer. R16 to R18 may be the same or different and are a hydrogen atom or a linear or branched alkyl group having 1 to 12 carbon atoms, preferably a hydrogen atom or a linear or branched chain having 4 to 8 carbon atoms. Is an alkyl group. Hindered phenols may be used alone or 2
A combination of more than one species may be used.

The mixing ratio of the component (F) is 0.05 to 2.
0 mass%, preferably 0.1 to 1.5 mass%, more preferably 0.1 to 1.0 mass%. 0.0
If the amount is less than 5% by mass, a sufficient antioxidant ability may not be obtained, and if the amount exceeds 2.0% by mass, the effect is saturated, which is economically disadvantageous.

The benzotriazole and the derivative thereof as the component (G) are derivatives obtained by reacting a benzotriazole having a structure represented by the following formula 9 with a water-soluble amine, a fatty acid ester and the like. Benzotriazole and its derivatives may be used alone or in combination of two or more.

[0034]

Formula 9

The compounding ratio of benzotriazole and its derivative is 0.001 to 0.05% by mass, preferably 0.0
03-0.02% by mass. If the compounding ratio is less than 0.001% by mass, sufficient metal corrosion inhibitory property may not be obtained, and if it exceeds 0.05% by mass, the effect is saturated, and it is economically disadvantageous.

Examples of the alkyl succinic acid derivatives of the component (H) include alkyl succinic amides and alkyl succinic acid esters. Preferred alkyl succinic acid derivatives are represented by the following formulas 10 and 11. Has a structure.

[0037]

Formula 10 Equation 11

In the above formulas 10, 11, R19, R21, R2
2 is an alkyl or alkenyl group having 6 to 18 carbon atoms, and R20 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. R19 is preferably a compound having 10 to 14 carbon atoms.
And particularly preferably dodecenyl or dodecadienyl. Preferred R21 and R22 are
It is an alkyl group or an alkenyl group having 8 to 16 carbon atoms. Specific examples of R19, R21, and R22 include hexyl, octyl, nonyl, decyl, undecyl, dodecyl, tetradecyl, heptadecyl, octadecyl, hexenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tetradecenyl, heptadecenyl, octadenyl, octadenyl, and octenylenyl. , Nonadienyl, decadienyl, undecadienyl, dodecadienyl, tetradecadienyl, heptadecadienyl, octadecadienyl and the like. Specific examples of R20 include n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, 2-methylbutyl and the like. Alkyl succinic acid derivatives are
It may be used singly or in combination of two or more, but is preferably a combination of two or more, and more preferably a combination of a partial ester of alkenyl succinic acid and an alkyl succinamide. .

The mixing ratio of the component (H) is from 0.01 to 0.1.
It is 3% by mass, preferably 0.03 to 0.1% by mass, and more preferably 0.03 to 0.07% by mass. If the compounding ratio is less than 0.01% by mass, a sufficient metal corrosion inhibitory property may not be obtained, and if it exceeds 0.3% by mass, the effect is saturated and it is economically disadvantageous.

The lubricating oil for sintered metal bearings of the present invention can be produced by blending each of the above components with a base oil, mineral oil or synthetic oil. The method of mixing (mixing method and addition method) of each component to the base oil is not particularly limited, and can be performed by various methods, and the mixing order and the addition order can be performed by various methods. For example, each component may be sequentially added to the base oil, or each component may be mixed in advance and this mixture may be added to the base oil.

[0041]

EXAMPLES In Examples and Comparative Examples, base oils (A) to
(H) The component was blended to prepare a lubricating oil for a sintered metal bearing, and the abrasion resistance and friction coefficient of each lubricating oil were evaluated. In each of the examples and comparative examples, the base oil and each component used for preparing the lubricating oil are as follows.

(Base oil) A highly refined paraffinic mineral oil, which is obtained by solvent extraction of a vacuum distillation distillate with furfural, dewaxing with methyl ethyl ketone, and further hydrotreating mineral oil and synthetic oil with poly-α- An olefin was used. The kinematic viscosity at 40 ° C. is in the range of 10 to 30 mm ² / s.

(Component A) Acid phosphate: R1
_But straight or acid phosphate (B component) of the branched acid phosphate amine salt of -C _{8 H 17:} the acid phosphate of oleylamine salt (C component) phosphite: R5, R6 are, -C ₁₂ H
₂₅ linear or branched phosphites (D component) alkylated diphenylamine: R7, R8
Is a mixture of any combination of a hydrogen atom, —C ₄ H ₉ , and —C ₈ H ₁₇ linear or branched (E component) alkylated phenyl-α-naphthylamine:
Straight or branched chain (F component) hindered phenols R9 is _-C 8 _{H 17:} R10, at R11 is tert- butyl group, R12 is a hydrogen atom 2,6-di -tert- butylphenol (G component ) Benzotriazole and derivatives thereof: benzotriazole represented by formula 9 (Component H) alkyl succinic acid derivative: In formula 10,
R18 is an alkyl group having 12 carbon atoms, and R19 is an alkyl group having 5 carbon atoms.
Alkyl succinic acid derivatives which are alkyl groups

(Evaluation method) Evaluation of abrasion resistance <Shell four ball test>: ASTM D2
The wear scar diameter was measured using the test device No. 783 under the following conditions. Evaluation of friction coefficient <SRV> The friction coefficient after 60 minutes was measured under the following conditions using an SRV friction and wear tester manufactured by optimol. Evaluation of thermal stability <Sludge test method> JIS K25
The test was based on the thermal stability test established in No. 40. Evaluation of corrosion stability to metal The corrosion stability to metal was evaluated according to the degree of discoloration of the copper plate, according to the method established in JIS K 2513. The degree of discoloration is evaluated in 12 steps from 1a to 4c, and 1a shows the result with the least degree of discoloration (best corrosion stability) and 4c with the most degree of discoloration (worst corrosion stability). . Evaluation of rust prevention The rust prevention was evaluated in accordance with the method defined in JIS K 2510, and the rust prevention was evaluated by the degree of rust. The degree of rust was evaluated based on “no rust” and “rusted”, and in the case of “rusted”, evaluation was made on three levels: slight, medium, and advanced.

Examples 1 to 8 and Comparative Examples 1 and 2 Base oils and A to H components were blended in the proportions (% by mass) shown in the upper row of Tables 1 and 2 to provide lubrication for sintered metal bearings in comparison with the present invention. Oils were prepared, and various performances of the respective lubricating oils were evaluated.

[0046]

[Table 1-1]

[0047]

[Table 1-2]

[0048]

[Table 1, 3]

[0049]

[Table 2]

[0050]

Industrial Applicability As described above, the present invention relates to a lubricating oil suitable for use in a bearing made of a sintered metal, and is not only excellent in wear resistance and friction reducing effect, but also
A low coefficient of friction can be maintained for a long time. As a result, the bearing made of sintered metal can be lubricated with a very thin oil film thickness, and the oil life can be prolonged even when the temperature locally rises.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C10M 133/38 C10M 133/38 137/02 137/02 137/04 137/04 137/08 137/08 / / C10N 30:06 C10N 30:06 30:08 30:08 40:02 40:02 F term (reference) 4H104 BB05C BB35C BE07C BE11C BE26C BH02C BH03C BH05C DA02A EB02 LA03 LA04 PA01

Claims (3)

[Claims] 1. A base oil comprising (A) 0.05 to 5.0% by mass of an acid phosphate, (B) 0.05 to 5.0% by mass of an amine salt of an acid phosphate, and (C) 0.05 of a phosphite A lubricating oil for sintered metal bearings containing at least one member selected from the group consisting of -5.0 mass%. 2. An alkylated diphenylamine (D) 0.05 to 2.0% by mass, an alkylated phenyl-α-naphthylamine (E) 0.05 to 2.0% by mass, (F)
The lubricating oil for a sintered metal bearing according to claim 1, wherein the lubricating oil contains at least one selected from 0.05 to 2.0 mass% of hindered phenols. (G) benzotriazole 0.0
01-0.05% by mass, its derivative 0.001-0.0
The lubricating oil for a sintered metal bearing according to claim 1 or 2, comprising at least one selected from 5% by mass and (H) an alkyl succinic acid derivative in an amount of 0.01 to 0.3% by mass.