JP2005132900A - Grease composition and roller bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grease composition excellent in producing quietness, longevity of acoustic level and low torque in particular, and a roller bearing using the same. <P>SOLUTION: The grease composition contains a thickening agent consisting of a metal soap or a polyurea compound and a base oil containing a specific alkyl naphthalene. The roller bearing, in which a plurality of rolling elements are held free-rotatably between the inner ring and the outer ring, is charged with the above grease composition. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a grease composition and a rolling bearing, and more particularly to a grease composition suitable for a bearing that requires quietness, long acoustic life, and low torque, such as electrical information equipment and a fan motor, and a rolling in which the grease is sealed. Related to bearings.

  In electrical information equipment, industrial machinery motors, fan motors, etc., comfort, power saving, and high durability are pursued. For this reason, grease-sealed rolling bearings used in the motor parts of these devices are required to have better quietness, lower torque, and longer acoustic life. These required performances are said to deteriorate as the deterioration of the lubricant accelerates. Among them, the increase in the base oil viscosity and the generation of deteriorated products due to the oxidative degradation of the grease base oil greatly affect the acoustic performance and torque performance, and are regarded as issues when satisfying the required performance.

  Conventionally, mineral oil-based grease has been widely used for rolling bearings used in these devices. However, although mineral oil-based grease is inexpensive, it has a problem that it is inferior in sound durability performance compared with synthetic oil-based grease. In addition, synthetic oil-based greases based on silicone oil, fluorine oil, and polyphenyl ether oil that are excellent in oxidation resistance are also used (see, for example, Patent Document 1). However, these base oils are expensive and not universal.

JP 2002-221231 A

  The present invention has been made in view of such circumstances, and an object thereof is to provide a grease composition that is inexpensive, quiet, has a long acoustic life and low torque, and a rolling bearing in which the grease composition is enclosed. To do.

In order to achieve the above object, the present invention provides the following grease composition and rolling bearing.
(1) A grease composition comprising a thickener comprising a metal soap or a polyurea compound and a base oil containing an alkylnaphthalene represented by the general formula (I).

_{(R 1} is a saturated alkyl of linear or branched of _C 12 _{-C 20} carbon chain _length, R 2, _{R 3} is a saturated straight chain or branched of _C 12 _{-C 20} carbon chain length It is alkyl or hydrogen, and R _{1 to} R ₃ may be the same or different from each other.)
(2) The thickener is contained in an amount of 5 to 40% by weight based on the total amount of the grease composition, and the alkylnaphthalene represented by the general formula (I) is contained in an amount of 30% or more based on the total amount of the base oil. The grease composition as described in (1) above, which is characterized by
(3) A rolling bearing in which a plurality of rolling elements are rotatably held between an inner ring and an outer ring and a grease composition is enclosed, and the grease composition described in (1) or (2) is enclosed. A rolling bearing characterized by that.

  According to the present invention, the use of an alkylnaphthalene having excellent oxidation resistance as a base oil provides a grease composition that is inexpensive but quiet, has a long acoustic life, and low torque. Further, by encapsulating this grease composition, a rolling bearing suitable for electrical information equipment, fan motors, etc. is provided with quietness, long acoustic life and low torque.

  Hereinafter, the present invention will be described in detail.

(Grease composition)
The grease composition of the present invention uses a base oil containing an alkylnaphthalene represented by the following general formula (I).

(I) wherein, _{R 1} is a saturated alkyl of linear or branched of _C 12 _{-C 20} carbon chain _length, R 2, _{R 3} is straight-chain carbon chain length is _C 12 _{-C 20} Or it is branched saturated alkyl or hydrogen, and R _{1 to} R ₃ may be the same or different. In particular, any one or two of R _{1 to} R ₃ is preferably monoalkylnaphthalene or dialkylnaphthalene substituted with a hydrocarbon group having 16 and 18 carbon atoms.

  The alkylnaphthalene can be used in combination with other lubricating oils as necessary. For example, when it is necessary to reduce the bearing starting torque at a low temperature, the flow point at the low temperature can be improved by lowering the pour point of the base oil by mixing and using another synthetic oil. However, the alkylnaphthalene is preferably contained in an amount of 30% by mass or more based on the total amount of the base oil in order to bring out its excellent oxidation resistance.

  As the lubricating oil that can be mixed and used, those having excellent heat resistance and oxidation resistance are preferable, and synthetic hydrocarbon oil, ether oil, and ester oil are preferable. Specifically, poly-α-olefin oil or the like is used as the synthetic hydrocarbon oil, dialkyl diphenyl ether oil, alkyl triphenyl ether oil, alkyl tetraphenyl ether oil or the like is used as the ether oil, and diester oil or neopentyl is used as the ester oil. Type polyol ester oils, or complex ester oils and aromatic ester oils thereof can be used. These lubricating oils may be used alone or in combination with the above-mentioned alkylnaphthalene. In particular, heat resistance for improving lubrication performance in the temperature range of about -30 ° C to 130 ° C, especially when electrical information equipment and industrial machinery motors are used, and low temperature fluidity taking into account the generation of unusual noise at particularly low temperatures Then, it is particularly preferable to use a mixture with a polyol ester oil, an aromatic ester oil, or a synthetic hydrocarbon oil.

The kinematic viscosity of the base oil is preferably 20 to 120 mm ² / s at 40 ° C. in consideration of the low temperature fluidity. Considering the rotational torque performance, it is more preferably 20 to 70 mm ² / s at 40 ° C.

  In the grease composition of the present invention, a polyurea compound is used because it has heat resistance as a thickener, is inexpensive, and has good acoustic characteristics. As the polyurea compound, diurea, triurea, tetraurea or higher polyurea compounds can be used, and diurea represented by the following general formula (II) is particularly preferable.

In formula (II), R ₅ represents an aromatic hydrocarbon group having 6 to 15 carbon atoms, and R ₄ and R ₆ represent a hydrocarbon group or a condensed hydrocarbon group, which may be the same or different. In R ₄ and R ₆ , the hydrocarbon group may be either an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and the condensed hydrocarbon group preferably has 9 to 19 carbon atoms.

The diurea represented by the general formula (II) is a ratio of 2 moles of monoamines containing R ₄ or R ₆ in the skeleton to 1 mole of diisocyanate containing R ₅ in the skeleton in the base oil. It is obtained by reacting with

As the diisocyanate containing R ₅ in the skeleton, diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, biphenylene diisocyanate, dimethyldiphenylene diisocyanate, or alkyl substituted products thereof can be suitably used.

Monoamines containing a hydrocarbon group in the skeleton as R ₄ or R ₆ include aniline, cyclohexylamine, octylamine, toluidine, dodecylaniline, octadecylamine, hexylamine, heptylamine, nonylamine, ethylhexylamine, decylamine, undecylamine, Dodecylamine, tetradecylamine, pentadecylamine, nonadecylamine, eicodecylamine, oleylamine, linoleylamine, linolenylamine, methylcyclohexylamine, ethylcyclohexylamine, dimethylcyclohexylamine, diethylcyclohexylamine, butylcyclohexylamine, propylcyclohexylamine, amyl Cyclohexylamine, cyclooctylamine, benzylamine, benzhydrylami , Phenethylamine, methyl benzylamine, biphenyl amine, phenyl isopropylamine, can be suitably used phenylhexylamine like.

Further, as monoamines containing a condensed ring hydrocarbon group in the skeleton as R ₄ or R ₆ , for example, indene amine compounds such as aminoindene, aminoindane, and amino-1-methyleneindene, aminonaphthalene (naphthylamine), aminomethylnaphthalene , Aminoethylnaphthalene, aminodimethylnaphthalene, aminocadalene, aminovinylnaphthalene, aminophenylnaphthalene, aminobenzylnaphthalene, aminodinaphthylamine, aminobinaphthyl, amino-1,2-dihydronaphthalene, amino-1,4-dihydronaphthalene, aminotetrahydro Naphthalene-based amino compounds such as naphthalene and aminooctalin, condensed bicyclic amine compounds such as aminopentalene, aminoazulene and aminoheptalene, aminofluorene, amino- -Aminofluorene-based amine compounds such as phenylfluorene, aminoanthracene, aminomethylanthracene, aminodimethylanthracene, aminophenylanthracene, anthracene-based amine compounds such as amino-9,10-dihydroanthracene, aminophenanthrene, amino-1,7 Phenanthreneamine compounds such as dimethylphenanthrene and aminoretene, condensed bicyclic amine compounds such as aminobiphenylene, amino-s-indacene, amino-as-indacene, aminoacenaphthylene, aminoacenaphthene and aminophenalene, aminonaphthacene , Aminochrysene, aminopyrene, aminotriphenylene, aminobenzoanthracene, aminoaceanthrylene, aminoaceanthrene, aminoacephenanthrylene, amino Condensed tetracyclic amine compounds such as noacephenanthrene, aminofluoranthene and aminopreaden, condensed pentacyclic amines such as aminopentacene, aminopentaphene, aminopicene, aminoperylene, aminodibenzoanthracene, aminobenzopyrene and aminocholanthrene A compound, a condensed polycyclic (six or more ring) amine compound such as aminocoronene, aminopyrantolen, aminoviolanthrene, aminoisoviolanthrene, and aminoobalene are preferably used.

  Metal soap can also be used as a thickener. As the metal soap, an alkali metal salt synthesized from an alkali metal or alkaline earth metal hydroxide and a higher fatty acid having 10 or more carbon atoms or a higher hydroxy fatty acid having 10 or more hydroxyl groups and one or more hydroxyl groups, and Alkaline earth metal salts are preferable, and lithium soap, calcium soap, sodium soap, aluminum soap and the like are mentioned. In particular, lithium stearate and / or lithium 12-hydroxystearate synthesized from lithium hydroxide and higher fatty acid is used. preferable.

  The thickener is contained in an amount of 5 to 40% by mass based on the total amount of the grease composition. If the amount of the thickener is less than 5% by mass, it is difficult to maintain the grease state, and if it exceeds 40% by mass, the grease composition is hardened so that a sufficient lubricating effect cannot be exhibited, and the rotational torque is also reduced. Rise. Considering acoustic durability performance and rotational torque performance, the amount of thickener is preferably 7 to 20% by mass of the total amount of the grease composition.

  Furthermore, in the grease composition of the present invention, various additives may be mixed as desired in order to further improve various performances. Additives are not limited, but for example, amine-based, phenol-based, sulfur-based, zinc dithiophosphate, zinc dithiocarbamate and other antioxidants, sulfonic acid metal salts, ester-based, amine-based, naphthenic acid metal salts, succinic acid Conventionally used in grease compositions, such as rust preventives such as derivatives, extreme pressure agents such as phosphorus, zinc dithiophosphate and organic molybdenum, oil improvers such as fatty acids and animal and vegetable oils, metal deactivators such as benzotriazole These additives can be used alone or in admixture of two or more. In addition, the addition amount of these additives will not be specifically limited if it is a grade which does not impair the objective of this invention.

(Rolling bearing)
The present invention also relates to a rolling bearing in which the above grease composition is enclosed. There is no limitation on the structure and configuration of the rolling bearing itself, and for example, a ball bearing 1 shown in a sectional view in FIG. 1 can be exemplified. This ball bearing 1 holds a plurality of balls 13 rotatably between an inner ring 10 and an outer ring 11 via a cage 12, and further in the bearing space S formed by the inner ring 10, the outer ring 11 and the balls 13. The grease composition (not shown) was filled and sealed with a seal 14. The filling amount of the grease composition may be the same as the conventional one.

  The rolling bearing of the present invention is suitable for electrical information equipment, fan motors, etc. because of its quietness, long acoustic life and low torque due to the properties of the above-mentioned grease composition.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not restrict | limited by these Examples.

(Preparation of grease)
A test grease was prepared according to the following formulation with the formulation shown in Table 1. The additive composition of the grease to be tested was all the same.
<Production Example I—Thickener is Diurea>
Half of the required amount of base oil was placed in the first container, and diphenylmethane-4,4-diisocyanate was added and dissolved therein. Also, half the required amount of the same base oil was placed in the second container, and octylamine was added and dissolved therein. And the content of the 2nd container was inject | poured into the 1st container, and it was made to react, stirring at about 70 degreeC. Thereafter, the reaction was terminated by heating to 130 ° C., an antioxidant and a rust inhibitor were added, and milling and defoaming were performed to obtain a grease composition.
<Production Example II-Thickener is metal soap>
Lithium stearate was added to the base oil, the temperature was raised to 210 ° C. with stirring, and after complete melting, the mixture was quenched in a container on a cooled flat plate. Thereafter, an antioxidant and a rust inhibitor were added, and milling and defoaming were performed to obtain a grease composition.

The test grease was subjected to various evaluations shown below.
(Sound endurance test)
Test bearing: Single-row deep groove ball bearing (Nippon Seiko Co., Ltd. designation number “608”: inner diameter 8 mm, outer diameter 22 mm, width 7 mm)
・ Rotation speed: 3000 min ^-1
・ Axial load: 29.4N
・ Bearing temperature: 100 ℃
・ Grease filling amount: 25% of bearing space volume
The test bearing was continuously rotated under the above conditions, and the sound of the bearing was measured using an Anderon meter at regular intervals. The rotation time required for the test bearing of Comparative Example 1 to rise by 5 Anderon from the initial Anderon value was taken as 1, and the relative value was taken as the acoustic life. The results are also shown in Table 1.

(Torque test)
Test bearing: Single-row deep groove ball bearing (Nippon Seiko Co., Ltd. designation number “608”: inner diameter 8 mm, outer diameter 22 mm, width 7 mm)
・ Rotation speed: 1800 min ^-1
・ Axial load: 29.4N
・ Bearing temperature: 25 ℃
The test bearing was continuously rotated under the above conditions, and the rotational torque after 3 minutes was measured. The rotational torque value of the test bearing of Comparative Example 1 was set to 1, and the relative value was obtained. The results are also shown in Table 1.

  As shown in Table 1, it can be seen that the test bearings of the examples according to the present invention are remarkably excellent in acoustic life and have low torque.

It is sectional drawing which shows an example (ball bearing) of the rolling bearing of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ball bearing 10 Inner ring 11 Outer ring 12 Cage 13 Ball 14 Seal

Claims (3)

A grease composition comprising a thickener comprising a metal soap or a polyurea compound and a base oil containing an alkylnaphthalene represented by the general formula (I).

_{(R 1} is a saturated alkyl of linear or branched of _C 12 _{-C 20} carbon chain _length, R 2, _{R 3} is a saturated straight chain or branched of _C 12 _{-C 20} carbon chain length It is alkyl or hydrogen, and R _{1 to} R ₃ may be the same or different from each other.) The thickener is contained in an amount of 5 to 40% by weight based on the total amount of the grease composition, and the alkylnaphthalene represented by the general formula (I) is contained in an amount of 30% or more based on the total amount of the base oil. The grease composition according to claim 1. A rolling bearing comprising a plurality of rolling elements held between an inner ring and an outer ring so as to freely roll and enclosing the grease composition, wherein the grease composition according to claim 1 or 2 is enclosed. bearing.

Images