JP2001172658A - Lubricating oil composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricating oil composition having excellent wear resistance and capable of improving the easiness and reliability of designing a sintered oil-impregnated bearing used for a spindle motor or the like and having a long life. SOLUTION: The lubricating oil composition is characterized in that aluminum oxide having a center particle diameter of 10 nm to 1 μm is blended in a base oil in an amount of 0.01 to 10% by weight. Additives such as a rust agent, a metal deactivator, and a dispersant can be blended, and physical properties such as low evaporation properties are further improved. This lubricating oil composition is suitable for bearings of a spindle motor having a slide bearing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sintered oil-impregnated bearing having a self-lubricating function by impregnating a porous body made of sintered metal or the like with lubricating oil (including lubricating grease), and a bearing surface. The present invention relates to a lubricating oil composition suitable for a dynamic pressure type porous oil-impregnated bearing in which a sliding surface of a rotating shaft is levitated and supported by a lubricating oil film formed by a dynamic pressure effect of a dynamic pressure groove provided in a laser beam printer (LBP). Models that require high rotational accuracy at high speeds, such as polygon scanner motors and spindle motors for magnetic disk drive devices (HDD),
Suitable for devices driven at high speed under the condition that a large unbalance load is applied by loading a disk, such as a spindle motor for an optical disk device such as DVD-ROM, DVD-RAM or a magneto-optical disk device such as MO. It relates to a lubricating oil composition.

[0002]

2. Description of the Related Art In such small spindle motors related to information equipment, further improvement in rotational performance and reduction in cost are required, and as a means therefor, lubricating oil having excellent lubricating properties is required. ing. Synthetic oils are used to improve the thermal stability of lubricating oils, and various organometallic antiwear agents are used to improve the wear resistance. At present, nothing that satisfies is satisfied. In particular, organometallic antiwear agents such as organozinc and organomolybdenum are not preferred because they can hinder thermal stability.

It is common practice to mix lubricating oils with solid lubricants such as molybdenum disulfide and graphite and fine ceramics such as boron nitride to improve the lubricating performance (see, for example, JP-A-5-125380). Gazette, Tribology Data Book: Published by Techno System Co., Ltd.), which is not enough to achieve higher abrasion resistance, and among them, there is a problem of coloring in black.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lubricating oil composition capable of enhancing lubricating properties of industrially used lubricating oil and extending the life of a bearing.

[0005]

The present invention provides a base oil containing aluminum oxide having a center particle size of 10 nm to 1 μm in an amount of 0.01 to 1 μm.
It is a lubricating oil composition characterized by being blended at 0% by weight. Further, the present invention provides the above lubricating oil composition comprising a base oil and one or more additives selected from the group consisting of an antioxidant, a rust inhibitor, a metal deactivator, and a dispersant. It is. Further, the lubricating oil composition of the present invention is to be impregnated or applied to the slide bearing in a spindle motor provided with the slide bearing.

First, the aluminum oxide used in the present invention is obtained by oxidation of aluminum, ignition of aluminum hydroxide,
Heating of aluminum chloride hydrate and aluminum nitrate (1
(80 to 200 ° C.), and any commercially available product may be used as it is or after classification. Aluminum oxide includes α, β, and γ types, and α-type is the most excellent in terms of wear resistance. Also,
Aluminum oxide needs to have a central particle diameter of 1 μm or less and 10 nm or more, and preferably has a central particle diameter of 0.1 to 0.3 μm. The smaller the center particle size, the better the dispersibility is, but there is a problem in handling (dispersion into the atmosphere), so it is advantageous to set the center particle size to 0.1 μm or more. Also, 90% or more of the aluminum oxide is 10%.
It is preferably in the range of nm to 1 μm. The addition amount of aluminum oxide to the base oil is 0.01 to 10% by weight.
And preferably 0.1 to 2% by weight. If it is less than 0.1% by weight, the effect of abrasion resistance cannot be obtained, and if it exceeds 10% by weight, long-term storage cannot be performed.

As the base oil used in the present invention, a non-aqueous base oil such as a hydrocarbon lubricating oil can be used. It is common to use polar water or the like as a dispersion solvent, and aluminum oxide dispersed in water is widely known as an abrasive. However, in the present invention, a lubricant is prepared by dispersing aluminum oxide in a hydrocarbon-based lubricating oil. As the hydrocarbon-based lubricating oil, mineral oil, poly-α-olefin hydride, ethylene-α-olefin copolymer hydride, ester, alkyl diphenyl ether, and the like can be used. Those classified as oils are preferred.

[0008] The lubricating oil composition of the present invention may contain various additives usually added to lubricating oils, in addition to the above-mentioned aluminum oxide. Preferably, an antioxidant,
It is preferable to mix one or more additives selected from the group consisting of a rust inhibitor, a metal deactivator, and a dispersant.

As the rust preventive, known rust preventives such as a carboxylic acid ester and a zinc salt of an organic sulfonic acid can be used. The carboxylic acid ester is not particularly limited as long as it is a carboxylic acid ester known as a rust preventive, but is preferably an ester of an aliphatic carboxylic acid having an amino group. This carboxylic acid ester exhibits sufficient rust prevention without inhibiting the wear resistance of the lubricating oil. As the carboxylic acid ester to be used, for example, aminosuccinic acid esters and derivatives thereof are suitable. As the organic zinc salt of sulfonic acid, zinc salt of dinonylnaphthalenesulfonic acid is preferable. Normally, mineral oil is used as a carrier for the rust preventive agent, but since a large amount of sludge is generated and lubrication performance is deteriorated, a carrier using a poly-α-olefin as a carrier is preferable. Suitable commercial products include, for example, NA-SUL ZS / PAO manufactured by King Industries.
The amount of the rust inhibitor added to the base oil is 0.01 to 3% by weight,
Preferably it is 0.01 to 0.1% by weight. If the amount of the rust inhibitor is less than 0.01% by weight, there is no rust prevention effect and
Exceeding the weight percent is not preferred because turbidity occurs and quality is poor.

As the metal deactivator, benzotriazole and its derivatives are typical, but there are also imidazoline and pyridine derivatives. Many of these compounds are effective at least in compounds having an N—C—N bond, and have an effect of forming an inert film on the metal surface and an antioxidant effect. Other than these, there are compounds having an N—C—S bond, but from the viewpoint of solubility in base oil and volatility,
Benzotriazole derivatives are effective. The mixing ratio of the metal deactivator is preferably in the range of 0.03 to 5% by weight based on the base oil.

As the antioxidant, one or more antioxidants selected from the group consisting of phenolic, amine or sulfur-based antioxidants which act as peroxide decomposing agents acting as free radical chain reaction terminators. The agents can be used alone or as a mixture. Suitable antioxidants include amine-based agents, phenol-based agents, or a combination of both. Examples of phenolic antioxidants include 2,6-di-t
-Butylphenol, 4,4′-methylenebis (2,6
-Di-t-butylphenol), 2,6-di-t-butyl-4-ethylphenol, 2,6-di-t-4-n-
Butylphenol. From the viewpoint of evaporation characteristics and compatibility with the base oil, 4,4′-methylenebis (2,6-
Di-t-butylphenol) is preferred. Examples of the amine-based antioxidant include dioctyldiphenylamine and phenyl-α-naphthylamine. Dioctyl diphenylamine is preferred from the viewpoint of evaporation characteristics and compatibility with the base oil. In consideration of the solubility in the base oil, the compounding amount of the amine-based antioxidant is 0.1 to 10% by weight and the phenol-based antioxidant is 0.1 to 10% by weight based on the base oil. preferable. When used alone, the amine-based antioxidant is preferably 0.1 to 10% by weight.

As the dispersant, a silane coupling agent and a polymer dispersant can be used. Preferred are polymeric dispersants, and among them, dispersants having a polyoxyalkylene group and an acid anhydride group are preferred. Suitable commercial products include
For example, Maria Rim AKM-0531 manufactured by NOF Corporation is suitable.

The lubricating oil composition of the present invention may contain a pour point depressant, if necessary, as long as the object of the present invention is not impaired.
Other additives such as a metal detergent, an oil agent, a surfactant, an antifoaming agent, a friction modifier, and a thickener can be blended according to the application.

Although the lubricating oil composition of the present invention can be used for various applications, it is suitable for a slide bearing used in a small spindle motor for information equipment. By impregnating or applying the lubricating oil composition to the slide bearing of the spindle motor, the motor life can be prolonged.

[0015]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. Abbreviations of the components used in the examples and comparative examples are as follows. In addition, the compounding ratio is shown in% by weight. PAO4: Poly-α-olefin hydride (Olonite Japan: Synfluid 401) POE: Polyol ester (HATCO: Hat)
col2928) MM: Polymeric dispersant (Mariarim AKM- manufactured by NOF Corporation)
0531) α-Al: α-aluminum oxide (Sumitomo Chemical Co., Ltd .: Sumicorundum AA-03; central particle size 0.32 μm, purity>
L57: dioctyldiphenylamine Zn: zinc dinonylnaphthalenesulfonate (rust inhibitor) BTA: metal deactivator (benzotriazole derivative) KE: carboxylate ester BN: boron nitride (Mitsui Chemicals: MBN) -250)

Examples 1-7, Comparative Examples 1-4 The lubricating oil compositions (hereinafter referred to as lubricating oils) of Examples 1-3 and Comparative Examples 1-4 were prepared by blending the components in the proportions shown in Table 1. It was adjusted. In addition, “Bal” in Table 1 indicates that the whole is 100, and the rest other than the numerical value is the same. ASTM D for these lubricants
The evaluation was performed using the tester described in 3233. The test conditions were a rotation speed of 290 rpm and a load of 300
The test was carried out in a test time of 15 minutes, and the test items were measured for wear (mg) of the test piece and torque during the test.
The test piece used was specified by ASTM D3233. Table 2 shows the results.

[0017]

[Table 1]

[0018]

[Table 2]

As shown in Examples and Comparative Examples, by adding aluminum oxide, wear characteristics higher than that of boron nitride known as an antiwear agent can be obtained. Furthermore, even if the amount of addition was reduced, the same wear resistance was obtained, and the torque could be reduced. The significance of the present invention that aluminum oxide used for an abrasive is found to be usable as an antiwear agent is significant.

[0020]

The lubricating oil composition of the present invention can suppress the amount of abrasion and improve the abrasion resistance. Therefore, good characteristics can be obtained even with a very simple structure such as a sintered oil-impregnated bearing used for a spindle motor and the like, and the simplicity and reliability of the design of the sintered oil-impregnated bearing and its mounting device are improved. be able to. Further, by adding a viscosity index improver, a metal deactivator, an antioxidant, and the like to the lubricating oil composition of the present invention, various properties such as thermal stability and rust prevention performance, particularly the evaporation amount, are further improved. Can be done. Further, the aluminum oxide used in the present invention does not impair properties such as thermal stability of the base oil.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) C10N 30:04 C10N 30:04 30:10 30:10 30:12 30:12 30:14 30:14 40 : 02 40:02 (72) Inventor Yoshihiko Ojo 7-21-11 Nishigotanda, Shinagawa-ku, Tokyo Nippon Steel Chemical Co., Ltd. (72) Inventor Masamichi Hayakawa 10801 Haramura, Suwa-gun, Nagano Prefecture 2 Stock Association (72) Inventor Yasuyoshi Tsuno 10801, Haramura, Suwa-gun, Nagano 2 Futam (reference) 4H104 AA13A AA13C BA07A BA08A BB08A BB31A CA01A DA02A EA08A EA08C EB07 EB09 EB10 EB11 FA03 LA03 LA04 LA06 PA01 PA04

Claims (4)

[Claims] 1. A lubricating oil composition comprising a base oil containing 0.01 to 10% by weight of aluminum oxide having a center particle size of 10 nm to 1 μm. 2. The lubricating oil according to claim 1, wherein one or more additives selected from the group consisting of an antioxidant, a rust inhibitor, a metal deactivator and a dispersant are blended with the base oil. Composition. 3. The lubricating oil composition according to claim 1, wherein the base oil is a hydrocarbon base oil. 4. The lubricating oil composition according to claim 1, wherein said lubricating oil composition is impregnated or applied to said sliding bearing in a spindle motor provided with the sliding bearing.