JP2003292984A - Lubricant composition for rolling bearing and method for producing rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricant composition for a rolling bearing increasing the temperature and speed, reducing the dusting and prolonging the life without adversely affecting various characteristics of a rolling bearing. <P>SOLUTION: The lubricant composition for the rolling bearing comprises an ester oil having 10-500 mm<SP>2</SP>/s viscosity at 40°C and containing at least one of a diester oil or a polyol ester oil in an amount of ≥20 wt.% based on the total amount of a base oil and 0.05-10 wt.% of an antioxidant, 2-20 wt.% of a rust preventive and 0.5-10 wt.% of an oiliness agent. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing used for a hard disk drive (HDD), a video tape recorder (VTR), a digital audio tape recorder (DAT), a laser beam printer (LBP), etc., and particularly an oil plating. The present invention relates to a lubricant composition suitably applied for use. The present invention also relates to a method of manufacturing a rolling bearing using the lubricant composition.

[0002]

2. Description of the Related Art The computer-related industry has a short history of technological innovation in spite of its short history as compared with other industrial fields. In particular, one HDD model has a short existing period, and new models (high accuracy and compactness) have been introduced one after another by introducing new technology. With these, HD
Rolling bearings used in information equipment such as D are also subject to severe operating conditions such as high temperature use and high speed rotation of the outer ring, and at the same time, low torque, low jitter, long life and the like are desired.

[0003]

However, the conventional rolling bearings used in VTRs, HDDs, DATs, LBPs, etc. are lubricated by a grease-filled lubrication system, or the bearing raceways are lubricated with lubricating oil. However, none of them has a sufficient effect on low torque, low jitter, long life, etc. For example, in rolling bearings used in information equipment such as HDDs, grease lubrication is the mainstream, but the lubrication mode is not uniform due to uneven grease filling, and torque fluctuations are also present. Sometimes it helps.

Generally, in the grease lubrication as described above, there is a problem that the rotating torque becomes large due to the agitation resistance of the grease, and the grease scatters from the rolling bearing to pollute the use environment. Such a large torque or contamination of the operating environment causes VTR, HDD, DAT, L
It has a great adverse effect on the operation of BP and the like. For example, HDD
However, this is not preferable because it may lead to head damage or read / write errors. Therefore, although a small amount of grease is used to deal with the problem, problems such as insufficient lubrication action and deterioration of lubrication durability may occur in some cases. In addition, the lubricity is also improved by applying lubricating oil to the bearing raceway surface or the like for the initial lubrication regardless of the enclosed grease. However, even in this case, there is a problem that it is not possible to sufficiently deal with an HDD or the like which is used particularly in a severe environment of high temperature and high speed rotation.

On the other hand, it has been attempted to solve the above problems by applying lubricating oil to the bearing raceway surface without using any grease. For example, JP-A-5-149
In No. 343, lubricating oil (poly α-olefin oil, polyol ester oil, polyphenyl ether oil, silicone oil, fluorine oil, etc.) is applied to the inner and outer ring raceways, rolling elements, and cage surfaces to keep it cool. It proposes that the abnormal noise in can be prevented. However, no knowledge of acoustic characteristics under high temperature and high speed rotation has been obtained. Similarly, Japanese Patent Application Laid-Open No. 64-46011 discloses a rotary support device coated with lubricating oil, but the amount of lubricating oil cannot always be secured sufficiently, and it may be sufficient depending on the state of use. It is possible that durability cannot be ensured.

Therefore, the present invention has been made to solve the problems of the conventional grease-lubricated rolling bearing as described above and further the rolling bearing coated with lubricating oil, which adversely affects various characteristics of the bearing. , High temperature, high speed, low dust generation,
Using a lubricant composition for rolling bearings that can achieve a long life, and a rolling bearing that uses the above-mentioned lubricant for a rolling bearing, has good lubrication performance, high temperature, high speed, low dust generation, and long life. It is an object to provide a method of manufacturing a bearing.

[0007]

The above object of the present invention is to achieve the above object.
The viscosity at 40 ° C. is 10 to 500 mm ² / s, and the ester oil containing at least one of diester oil and polyol ester oil is contained in an amount of 20% by weight or more based on the total amount of the base oil.
A lubricant composition for rolling bearings, characterized in that it comprises 5 to 10% by weight of antioxidant, 2 to 20% by weight of rust inhibitor, and 0.5 to 10% by weight of oiliness agent.

A similar object is to immerse the assembled rolling bearing in the above-mentioned lubricant composition for rolling bearing of the present invention,
Centrifugal deoiling is carried out after pulling up, and the rolling bearing lubricant film is formed at least on the inner and outer ring raceway surfaces and on the surfaces of the rolling elements with a film thickness of 0.03 to 20 μm. It is also achieved by the method.

[0009]

The lubricant composition for rolling bearings of the present invention is particularly suitable for oil plaining of rolling bearings. The oil plating is usually formed as a thin film having a thickness of several tens of μm or less on the inner and outer ring raceways and the surface of rolling elements. In such a thin film, especially at high temperature and high speed rotation, the base oil constituting the lubricant composition is easily oxidized and deteriorated by thermal decomposition. Therefore, in the present invention, while increasing the heat resistance by containing a diester oil or a polyol ester oil in the ester oil as the base oil, while also ensuring the lubricity by specifying the viscosity thereof, further specific antioxidant and rust By adding a stopper, oxidation of the base oil due to thermal decomposition is suppressed and rust on the oil-coated surface is prevented.
Further, a rolling bearing plated with such a lubricant composition functions well even under use conditions of high temperature and high speed rotation, and has excellent durability.

The rolling bearing lubricant composition of the present invention and the method for producing the rolling bearing will be described in detail below.

The base oil used in the rolling bearing lubricant composition of the present invention contains an ester oil as an essential component. The ester oil is not particularly limited, but it is a diester oil obtained by the reaction of a dibasic acid and a branched alcohol, an aromatic ester oil obtained by the reaction of an aromatic tribasic acid and a branched alcohol, a polyhydric alcohol and a monobasic alcohol. A hindered ester oil obtained from the reaction of an acid is preferably used. Considering heat resistance (use conditions under high temperature and high speed), it is selected from aromatic ester oils and hindered ester oils, and it is particularly preferable to use them alone or in combination.

As diester oil, dioctyl adipate (DOA), diisobutyl adipate (DIB)
A), dibutyl adipate (DBA), dioctyl azelate (DOZ), dibutyl sebacate (DBS), dioctyl sebacate (DOS), methyl acetyl ricinoleate (MAR-N), etc. are mentioned.

Examples of aromatic ester oils include trioctyl trimellitate (TOTM), tridecyl trimellitate and tetraoctyl pyromellitate.

Examples of the hindered ester oil include those obtained by appropriately reacting the following polyhydric alcohols and monobasic acids. The monobasic acid reacted with the polyhydric alcohol may be used alone or in combination. Further, it may be used as a complex ester which is an oligoester of a polyhydric alcohol and a mixed fatty acid of dibasic acid / monobasic acid. Examples of the polyhydric alcohol include trimethylolpropane (TMP), pentaerythritol (PE), dipentaerythritol (DPE), neopentyl glycol (NPG), 2-methyl-2-propyl-1,3-propanediol (MPPD). Etc. The monobasic acids, mainly monovalent fatty acid C ₄ -C ₁₈ are used.
Specifically, for example, acetic acid, valeric acid, caproic acid, caprylic acid, enanthic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, mistyric acid, palmitic acid, beef fatty acid, threaric acid, caproic acid, undecylenic acid, Examples thereof include linderic acid, tudzuic acid, fizeteric acid, myristoleic acid, palmitoleic acid, petroselinic acid, oleic acid, elaidic acid, asclepic acid, vaccenic acid, sorbic acid, linoleic acid, linolenic acid, sabinic acid and ricinoleic acid.

The above ester oil contains at least 20% by weight of the total amount of the base oil, and in consideration of acoustic characteristics, pentaerythritol ester or dipentaerythritol ester alone or in a mixture of 40% by weight or more is contained in the ester oil. Is desirable. If the ester oil content is less than 20% by weight, high temperature / high speed durability cannot be sufficiently obtained. Moreover, the upper limit is not particularly limited.

The rolling bearing lubricant composition of the present invention comprises:
In addition to ester oil, synthetic hydrocarbon oil and ether oil may be added as a base oil component. Examples of synthetic hydrocarbon oils include poly-α-olefin oils and cooligomer synthetic oils of α-olefin and ethylene. Examples of ether oil include C such as diphenyl, triphenyl, and tetraphenyl.
Of ₁₂ -C ₂₀ (di) alkyl chains are derived include phenyl ether oil. Especially considering high temperature and high speed durability,
(Di) alkyl polyphenyl ether oils are preferred. The blending ratio of these is within 80% by weight from the above-mentioned regulation of the amount of ester oil.

The base oil has a kinematic viscosity of 40 mm at 10 mm ² /
s or more is required, and if it is less than 10 mm ² / s, the film-forming property during rotation is not sufficient and the acoustic characteristics are poor. Although the upper limit is not specified in particular, if the viscosity is too high, it is not preferable in handling and the torque is affected. Considering the viscosity grade of general bearing oil, the upper limit of the base oil viscosity is 500 mm ² / s.
Is.

As the rust preventive used in the lubricant composition for rolling bearings of the present invention, organic sulfonic acid metal salts or esters having good rust preventive properties are preferable. As the organic sulfonate, for example, dinonylnaphthalene sulfonic acid and heavy alkylbenzene sulfonic acid are used, and its metal salt includes calcium sulfonate, barium sulfonate, sodium sulfonate and the like.
Among the esters, sorbitan derivatives include sorbitan monolaurate, sorbitan trilaurate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, and sorbitan trioleate as partial esters of polybasic carboxylic acids and polyhydric alcohols. Examples of the alkyl ester type include polyoxyethylene laurate, polyoxyethylene oleate, and polyoxyethylene stearate.

For these rust preventives, organic sulfonic acid metal salts and esters can be used alone or as a mixture. The content of the rust preventive agent is 2% by weight or more based on the total amount of the lubricant composition. If the content of the rust inhibitor is less than 2% by weight, an effective rust preventive effect cannot be obtained. On the other hand, even if it is added in an amount of 20% by weight or more, the rust preventive effect corresponding to the increase in the added amount cannot be expected, which leads to a cost increase. Therefore, the content of the rust preventive agent is 2 to
20% by weight is preferred.

The oiliness agent used in the lubricant composition for rolling bearings of the present invention includes oleic acid as a higher fatty acid,
Examples of higher alcohols such as stearic acid include lauryl alcohol and oleyl alcohol, stearylamine and cetylamine for amines, and tricresyl phosphate for phosphate esters. The oiliness agent can further improve the lubricating performance such as abrasion resistance, and the above substances are used alone or as a mixture. The content of the oiliness agent is 0.5% by weight or more. If the content is less than 0.5% by weight, the wear reducing effect cannot be obtained. Further, even if it is added in an amount of 10% by weight or more, the effect corresponding to the increase in the addition amount cannot be expected, which leads to a cost increase. In consideration of acoustic characteristics and cost, the content of the oily agent is preferably 0.5 to 10% by weight. Further, 1 to 5% by weight is preferable.

The antioxidant used in the rolling bearing lubricant composition of the present invention is a mixture of a nitrogen-containing compound type antioxidant and a phenol type antioxidant. Examples of the nitrogen-containing compound type antioxidants include phenyl α-naphthylamine, diphenylamine, phenylenediamine, oleylamidoamine, and phenothiazine. Examples of phenolic antioxidants include p-tert-butyl-phenyl salicylate, 2,6-di-tert-butyl-p-phenylphenol, and 2,2′-methylenebis (4-methyl-6).
-Tert-butylphenol), 2,2'-methylenebis (4-methyl-6-tert-octylphenol), 4,4'-butylidenebis-6-tert-butyl-m-cresol), tetrakis [methylene-3-
(3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate] methane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert)
-Butyl-4-hydroxybenzyl) benzene, n-octadecyl-β- (4'-hydroxy-3 ', 5'-di-tert-butylphenyl) propionate, 2-n
-Octyl thio-4,6-di (4'-hydroxy-
3 ', 5'-di-tert-butyl) phenoxy-1,
3,5-triazine, 4,4'-thiobis- [6-te
rt-Butyl-m-cresol], 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, and other hindered phenols.

The content of these antioxidants is 0.05% by weight or more. If this content is less than 0.05% by weight, the antioxidant effect of the lubricating oil is reduced and sufficient lubricity cannot be maintained. Further, even if it is added in an amount of 10% by weight or more, the antioxidant effect of the lubricating oil cannot be expected in accordance with the increase of the addition amount, which leads to a cost increase. Therefore, in consideration of acoustic characteristics and cost, the content rate of the antioxidant is 0.
05 to 10% by weight is preferable. Further, 0.1 to 10% by weight is preferable. Further, the mixing ratio of the nitrogen-containing compound-based antioxidant and the phenol-based antioxidant is preferably 1: 9 to 9: 1. By setting this ratio, the antioxidant effect of the lubricating oil is improved and -It is possible to improve the acoustic characteristics due to high speed rotation. In addition, only one of the nitrogen-containing compound type antioxidant or the phenol type antioxidant,
No improvement in acoustic characteristics can be obtained.

The lubricant composition for rolling bearings of the present invention contains the above-mentioned substances as essential components, but contains an extreme pressure agent, a viscosity index improver, an antiwear agent, etc. within a range that does not impair the effect. Good.

In order to produce a rolling bearing by using the above-mentioned lubricant composition for rolling bearing, it is necessary to adopt a method capable of controlling the film thickness, and the following treatment is carried out.

First, the assembled rolling bearing is dipped in the above rolling bearing lubricant composition and pulled up. Then, centrifugal deoiling is carried out after the pulling up, whereby a film of the rolling bearing lubricant is formed in a predetermined film thickness on the inner and outer ring raceway surfaces, the rolling elements and the surface of the cage. Here, the rotation speed and time in centrifugal deoiling are adjusted so that the film thickness of the film of the lubricant composition for rolling bearings is 0.03 to 20 μm.
The thickness of the film of the lubricant composition for rolling bearings is 0.03 μm
If it is less than the above range, a portion where the lubricating oil does not exist partially occurs and durability becomes insufficient. On the other hand, when the film thickness exceeds 20 μm, the film of the lubricant composition for rolling bearings becomes a resistance to increase the rotational torque and increase the amount of dust generation. A particularly preferable film thickness is 1 to 10 μm.

[0026]

EXAMPLES The present invention will be clarified by the following examples and comparative examples. [Examples 1 to 22 and Comparative Examples 1 to 12] The components and amounts of the rolling bearing lubricant compositions used in Examples and Comparative Examples are as shown in Table 1. In addition, in [] in the table,
The content [wt%] in the entire lubricant composition is shown.
Therefore, the total of the numerical values in [] is 100. The viscosity of the base oil at 40 ° C. is also shown.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

[Table 3]

[0030]

[Table 4]

[0031]

[Table 5]

[0032]

[Table 6]

Then, the lubricant compositions of Examples and Comparative Examples were applied to the following bearings to prepare test pieces. ○ Type of bearing used Single-row deep groove ball bearing, non-contact rubber seal (V type), nominal number 695, dimensions are 5 mm inner diameter × 13 mm outer diameter × 4 mm width ○ Method of applying lubricant composition to bearing and film thickness Preparation method The bearing was dipped in a lubricant composition, and then pulled up and air was blown to drain the liquid to remove excess lubricant composition.
Furthermore, the lubricant composition remaining on the bearing was removed by a centrifugal separator. The film thickness was adjusted by adjusting the magnitude of the centrifugal force generated by the centrifugal separator and the duration of rotation. The film thickness of the lubricant composition formed on each subject is also shown in Table 1.

<Test Details> Various characteristic tests for the following items were conducted. (1) Bearing acoustic test Bearing rotation speed: 7,200 rpm (outer ring rotation) Axial load: 2 kgf Atmospheric temperature: 70 ° C. (judgment standard) Acoustic measurement of the bearing was performed using an Anderon meter, and a lubricant composition was applied. The bearing Anderon value immediately after (the initial Anderon value) and the bearing Anderon value after 5000 hours of rotation were compared to determine the acoustic characteristics. The value increased from the initial Anderon value is shown in Table 1 by the following symbols, and 2.5 or less was regarded as a pass. ☆: 0.5 or less Pass ◎: 0.6 to 1.0 Pass ○: 1.1 to 2.5 Pass △: 2.6 to 5.0 Fail ×: 5.1 or more Fail

(2) Anticorrosion test bearing: Atmosphere of inner ring and outer ring with nominal number 695: 20 ° C x 90% RH (3 hours) and 50 ° C x
The cycle of 90% RH (3 hours) is alternately repeated. Leave time: 7 days (criteria) Generation of rust was confirmed on the inner and outer rings with a microscope. The results are shown in Table 1 with the following symbols, and rust-free was passed. ○: No rust Pass △: Several points of rust failed ×: Many rust failed

(3) Measurement of dust generation amount The bearing was rotated at 7,200 rpm (outer ring rotation) in a sealed container, and the number of dust generated at that time was measured by an out particle counter to obtain the dust generation amount. . The amount of dust generated is
Particle size 0.1 present in 0.1 cf (cubic feet)
It was performed by counting the number of dust particles having a particle size of μm or more, and the dust generation amount of 150 particles or less after one hour passed was regarded as a pass. The measurement results are shown numerically in Table 1.

From the above test results, it was confirmed that the rolling bearings to which the lubricant compositions shown in the examples were applied had excellent characteristics in all of acoustic characteristics, rust preventiveness and dust generation amount. On the other hand, as in Comparative Examples, those not containing the component specified in the present invention or those in which the amount of the component is out of the range of the present invention have any of the acoustic characteristics, anticorrosiveness, and dust generation characteristics. It is inferior in characteristics.

[0038]

As described above, in the lubricant composition for rolling bearings of the present invention, the ester oil as the base oil contains the diester oil or the polyol ester oil to enhance the heat resistance and to regulate its viscosity. By adding a specific antioxidant and rust preventive while ensuring lubricity, oxidation of the base oil due to thermal decomposition is suppressed and rust on the oil-coated surface is prevented. . Therefore,
It is suitable as a lubricating oil for oil plating of bearings, and can solve the problem that the base oil constituting the lubricant composition has been conventionally oxidized and deteriorated by thermal decomposition, especially at high temperature and high speed rotation. In addition, a rolling bearing plated with such a lubricant composition has low dust generation, high rust resistance, while sufficiently securing the bearing acoustic performance even at high temperature and high speed rotation.
It is possible to realize low dust generation and long life.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C10M 129/40 C10M 129/40 129/76 129/76 133/06 133/06 133/12 133/12 135 / 10 135/10 137/04 137/04 F16C 33/32 F16C 33/32 33/34 33/34 33/64 33/64 33/66 33/66 Z // C10N 10:04 C10N 10:04 20: 02 20:02 30:06 30:06 30:08 30:08 40:02 40:02 (72) Inventor Atsushi Yokouchi 1-5-50, Shinmei Kugenuma, Kugenuma, Fujisawa-shi, Kanagawa (72) Invention Michiharu Naka, 1-5-50, Shinmei Kugenuma, Fujisawa-shi, Kanagawa F-Term (reference), NSK Ltd. EB09 EB10 FA01 LA03 LA04 PA01

Claims (5)

[Claims] 1. The viscosity at 40 ° C. is 10 to 500 mm ² /
s, an ester oil containing at least one diester oil or polyol ester oil is contained in an amount of 20% by weight or more based on the total amount of the base oil, and 0.05-10% by weight of an antioxidant, 2-20
A rolling bearing lubricant composition comprising a rust inhibitor in an amount of 0.5% by weight and an oiliness agent in an amount of 0.5 to 10% by weight. 2. The lubricant composition for a rolling bearing according to claim 1, wherein the ester oil contains 40 wt% or more of pentaerythritol ester or dipentaerythritol ester alone or in a mixture in the ester oil. 3. The rolling agent according to claim 1, wherein the antioxidant is a mixture of nitrogen-containing compound type antioxidant: phenol type antioxidant = 1: 9 to 9: 1. Bearing lubricant composition. 4. A rolling bearing assembled in the lubricant composition for a rolling bearing according to claim 1 is dipped, centrifugally deoiled after pulling up, and at least inner and outer ring raceways and A method for producing a rolling bearing, comprising forming a film of the lubricant composition for a rolling bearing on the surface of a rolling element to a film thickness of 0.03 to 20 μm. 5. The method of manufacturing a rolling bearing according to claim 4, wherein the film thickness of the coating composition of the lubricant composition for rolling bearings is 0.03 to 10 μm.