JP2004067940A - Grease composition and rotary bearing enclosing it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary bearing suitable for using under a high temperature, high speed, high load and high vibration, which has an excellent burn-in life and suppresses generation of a foreign sound at a low temperature, and to provide a grease composition suitable for the rotary bearing. <P>SOLUTION: The grease composition comprises a base oil containing an alkyl substituted diphenyl sulfide and a polyurea compound as a thickening agent, and the rotary bearing is prepared by enclosing the grease composition therein. <P>COPYRIGHT: (C)2004,JPO

Description

【００１１】
式中、Ｒ^１及びＲ^２は炭素数１０〜２０の炭化水素基であり、Ｒ^１及びＲ^２は互いに同一であっても異なるものであってもよい。また、ｍ、ｎは、１≦（ｍ＋ｎ）≦４を満たす０以上の整数を示す。特に、一般式（Ｉ）においてＲ^１及びＲ^２が炭素数１２または１４の炭化水素基であるジフェニルスルフィドのアルキル置換体が好ましい。
【００１２】
耐熱性に優れた基油としてポリフェニルエーテル、シリコーン油、フッ素油等が知られているが、ポリフェニレンエーテル油、フッ素油は非常に高価であり、シリコーン油は一般に潤滑性が悪いという欠点を有する。これに対し、本発明で用いるジフェニルスルフィドのアルキル置換体は、安価でありながらも耐熱性、潤滑性に優れ、更には耐酸化性、耐摩耗性にも優れるという利点を有する。
【００１３】
ジフェニルスルフィドのアルキル置換体は、単独で基油を構成することができるが、基油全量の３０質量％以上、好ましくは４０質量％以上を占めるように他の潤滑油と混合してもよい。ジフェニルスルフィドのアルキル置換体の含有量が基油全量の３０質量％未満になると、耐熱性、潤滑性、耐酸化性、耐摩耗性といった特性が十分に発現しなくなるおそれがある。
【００１４】
混合に使用する潤滑油としては、耐熱性及び耐酸化性に優れた潤滑油が好ましく、具体的には合成炭化水素油、エーテル油、エステル油が好適である。尚、合成炭化水素油としてはポリα−オレフィン油等を例示でき、エーテル油としてはジアルキルジフェニルエーテル油、アルキルトリフェニルエーテル油、アルキルテトラフェニルエーテル等を例示でき、エステル油としてはジエステル油、ネオペンチル型ポリオールエステル油またはこれらのコンプレックスエステル油、芳香族エステル油等を例示できる。これらの潤滑油は、単独でもよく、複数種を組み合わせて使用してもよい。また、高温、高速、高荷重及び高振動下での潤滑性能及び焼付き寿命の向上、更には極低温での異音発生の抑制を考慮すると、エステル油、特にペンタエリスリトールエステルやジペンタエリスリトールエステル等のポリオールエステル油、芳香族エステル油及び合成炭化水素油が好ましい。
【００１５】
上記の如く構成される基油は、低温での軸受起動トルクを低減させる上で、４０℃における動粘度で２０〜２００ｍｍ^２／ｓ、特に４０〜１５０ｍｍ^２／ｓであることが好ましく、他の潤滑油との組み合わせによりこの動粘度範囲に調整する。
【００１６】
一方、増ちょう剤として用いられるポリウレア化合物としては、ジウレア、トリウレア、テトラウレアあるいはそれ以上のポリウレア化合物が使用できるが、特に下記一般式（ＩＩ）で表されるジウレア化合物が好ましい。
Ｒ^３−ＮＨＣＯＮＨ−Ｒ^４−ＨＮＯＣＨＮ−Ｒ^５　・・・（ＩＩ）
【００１７】
式中、Ｒ^４は炭素数６〜１５の芳香族系炭化水素基を表し、Ｒ^３、Ｒ^５は炭化水素基または縮合炭化水素基を表し、同一でも異なっていてもよい。また、Ｒ^３、Ｒ^５において、炭化水素基は脂肪族炭化水素基、芳香族炭化水素基の何れでもよく、縮合炭化水素基の炭素数は好ましくは９〜１９である。
【００１８】
上記一般式（ＩＩ）で表されるジウレア化合物は、基油中で、Ｒ^４を骨格中に含むジイソシネート１モルに対し、Ｒ^３またはＲ^５を骨格中に含むモノアミンを合計で２モルの割合で反応させることにより得られる。
【００１９】
Ｒ^４を骨格中に含むジイソシネートとしては、ジフェニルメタンジイソアネート、トリレンジイソシアネート、キシリレンジイソシアネート、ビフェニレンジイソシアネート、ジメチルジフェニレンジイソシアネート、あるいはこれらのアルキル置換体等を好適に使用できる。
【００２０】
Ｒ^３またはＲ^５として炭化水素基を骨格中に含むモノアミンとしては、アニリン、シクロヘキシルアミン、オクチルアミン、トルイジン、ドデシルアニリン、オクタデシルアミン、ヘキシルアミン、ヘプチルアミン、ノニルアミン、エチルヘキシルアミン、デシルアミン、ウンデシルアミン、ドデシルアミン、テトラデシルアミン、ペンタデシルアミン、ノナデシルアミン、エイコデシルアミン、オレイルアミン、リノレイルアミン、リノレニルアミン、メチルシクロヘキシルアミン、エチルシクロヘキシルアミン、ジメチルシクロヘキシルアミン、ジエチルシクロヘキシルアミン、ブチルシクロヘキシルアミン、プロピルシクロヘキシルアミン、アミルシクロヘキシルアミン、シクロオクチルアミン、ベンジルアミン、ベンズヒドリルアミン、フェネチルアミン、メチルベンジルアミン、ビフェニルアミン、フェニルイソプロピルアミン、フェニルヘキシルアミン等を好適に使用できる。
【００２１】
Ｒ^３またはＲ^５として縮合炭化水素基を骨格中に含むモノアミンとしては、アミノインデン、アミノインダン、アミノ−１−メチレンインデン等のインデン系アミン化合物、アミノナフタレン（ナフチルアミン）、アミノメチルナフタレン、アミノエチルナフタレン、アミノジメチルナフタレン、アミノカダレン、アミノビニルナフタレン、アミノフェニルナフタレン、アミノベンジルナフタレン、アミノジナフチルアミン、アミノビナフチル、アミノ−１，２−ジヒドロナフタレン、アミノ−１，４−ジヒドロナフタレン、アミノテトラヒドロナフタレン、アミノオクタリン等のナフタレン系アミノ化合物、アミノペンタレン、アミノアズレン、アミノヘプタレン等の縮合二環系アミン化合物、アミノフルオレン、アミノ−９−フェニルフルオレン等のアミノフルオレン系アミン化合物、アミノアントラセン、アミノメチルアントラセン、アミノジメチルアントラセン、アミノフェニルアントラセン、アミノ−９，１０−ジヒドロアントラセン等のアントラセン系アミン化合物、アミノフェナントレン、アミノ−１，７−ジメチルフェナントレン、アミノレテン等のフェナントレン系アミン化合物、アミノビフェニレン、アミノ−ｓ−インダセン、アミノ−ａｓ−インダセン、アミノアセナフチレン、アミノアセナナフテン、アミノフェナレン等の縮合三環系アミン化合物、アミノナフタセン、アミノクリセン、アミノピレン、アミノトリフェニレン、アミノベンゾアントラセン、アミノアセントリレン、アミノアセアントレン、アミノアセフェナントリレン、アミノアセフェナントレン、アミノフルオランテン、アミノプレアデン等の縮合四環系アミン化合物、アミノペンタセン、アミノペンタフェン、アミノピセン、アミノペリレン、アミノジベンゾアントラセン、アミノベンゾピレン、アミノコラントレン等の縮合五環系アミン化合物、アミノコロネン、アミノピラントレン、アミノビオラントレン、アミノイソビオラントレン、アミノオバレン等の縮合多環系（六環以上）アミン化合物等が好適に用いられる。
【００２２】
上記ポリウレア化合物からなる増ちょう剤は、グリース組成物全量の５〜４０質量％となるように配合される。配合量が５質量％未満ではグリース状態を維持するのが困難となり、４０質量％を超える場合にはグリースが硬化し過ぎて十分な潤滑効果を発揮することができなくなる。より高温、高速、高荷重及び高振動下での使用を可能にすることを考慮すると、高温、高せん断によるグリースの軟化、また潤滑効果を勘案し、増ちょう剤の配合量は１０〜３０質量％とすることが好ましい。
【００２３】
また、本発明のグリース組成物においては、その各種性能を更に向上させるために、所望により種々の添加剤を添加してもよい。添加剤としては、制限されるものではないが、アミン系、フェノール系、硫黄系、ジチオリン酸亜鉛、ジチオカルバミン酸亜鉛等の酸化防止剤、スルフォン酸金属塩、エステル系、アミン系、ナフテン酸金属塩、コハク酸誘導体等の防錆剤、リン系、ジチオリン酸亜鉛、有機モリブデン等の極圧剤、脂肪酸、動植物油等の油性向上剤、ベンゾトリアゾール等の金属不活性剤等を単独で、もしくは適宜組み合わせて用いることができる。尚、これら添加剤の添加量は、本発明の目的を損なわない範囲であれば特に制限されるものではない。
【００２４】
また、本発明のグリース組成物の混和ちょう度は、ＮＬＧＩ　Ｎｏ．１〜Ｎｏ．３が好ましい。
【００２５】
（転がり軸受）
本発明はまた、上記のグリース組成物を封入した転がり軸受を提供する。但し、転がり軸受は、例えば図１に示すような玉軸受１を例示することができる。即ち、内輪１０と外輪１１との間に、保持器１２を介して複数の転動体である玉１３を転動自在に保持し、更に内輪１０、外輪１１及び玉１３で形成される軸受空間Ｓに上記のグリース組成物（図示せず）を所定量封入し、シール１４で封止して構成される。
【００２６】
本発明の転がり軸受は、封入したグリース組成物が上記の如く高温、高速、高荷重及び高振動下でも良好な潤滑効果を発揮するため、特に自動車の電装部品、エアコン補機であるオルタネータや中間プーリ、カーエアコン用電磁クラッチ等での使用に好適である。
【００２７】
【実施例】
以下、実施例及び比較例を挙げて本発明を更に説明するが、本発明はこれにより何ら制限されるものではない。
【００２８】
（実施例１〜７、比較例１〜３）
表１に示す如く基油に増ちょう剤を配合し、試験グリースを調製した。尚、各試験グリースとも増ちょう剤の配合量は一定とし、更に一定量の酸化防止剤及び防錆剤を添加してある。また、実施例における試験グリースの調製方法の一例を示すと以下のとおりである。
【００２９】
即ち、ジフェニルメタン−４，４−ジイソシアネートを、基油であるジフェニルスルフィドのアルキル置換体に溶解させた後、７０℃程度に加熱しながら、同一の基油にステアリルアミンを溶解したものと、同一の基油にシクロヘキシルアミンを溶解したものとを加え、攪拌して反応させ、その後１３０℃まで加熱して反応を修了させ、酸化防止剤及び防錆剤を所定量加え、ミル処理及び脱泡処理を行うことで、試験グリースを得た。
【００３０】
そして、各試験グリースを下記に示す（１）焼付き試験、（２）低温異音試験及び（３）蒸発減量試験に供した。
【００３１】
（１）焼付き試験
図１に示す構造を有し、内径φ２５ｍｍ、外径φ６２ｍｍ、幅１７ｍｍの接触ゴムシール付き深溝玉軸受に、軸受空間（Ｓ）の３０容積％を占めるように試験グリースを封入して試験軸受を作製した。試験は、図２に示す試験装置を用いて行った。図示される試験装置は、回転用シャフト２０を一対の支持用軸受２２，２２で支持し、その中間部に試験軸受２１を装着し、更に全体を所定温度に維持できるように恒温容器（図示せず）に収容する構成となっている。試験は、シャフト２０を回転させて試験軸受２１を内輪回転速度１００００ｍｉｎ^−１、軸受外輪温度１８０℃、ラジアル荷重１４７０Ｎ、アキシアル荷重９８Ｎの条件で連続回転させ、焼付きが生じて軸受外輪温度が１９５℃以上に上昇したとき、及び回転トルクが急上昇した場合に試験を終了し、それまでの時間を測定した。試験は各４例行い、比較例１の試験グリースを封入した試験軸受の焼付き時間を１とした相対値にて結果を表１に併記した。
【００３２】
（２）低温異音試験
上記焼付き試験で用いたものと同一の試験軸受を作製し、同一の試験装置を用いて内輪回転速度１８００ｍｉｎ^−１、軸受外輪温度−２０℃、アキシアル荷重９８Ｎの条件で試験軸受を連続回転させ、異音の発生の有無を確認した。結果を表１に併記した。
【００３３】
（３）蒸発減量試験
試験グリースを１５ｍｇ採取し、熱重量分析（ＴＧＡ）により、１６０℃で１２時間保持したときの減量を測定した。結果を表１に併記した。
【００３４】
【表１】

【００３５】
表１から明らかなように、本発明に従い、ジフェニルスルフィドのアルキル置換体を含有する基油に、ポリウレア化合物を増ちょう剤として配合したグリース組成物は、軸受の焼付き寿命を向上させ、低温での異音を発生することも無く，基油の蒸発量も少なく潤滑性能を長期にわたり維持できることがわかる。これに対し、基油がジフェニルスルフィドのアルキル置換体を含有しない比較例１の試験グリースでは、焼付き寿命及び基油の蒸発が多く、軸受の耐久性を向上させる効果は少ない。また、増ちょう剤がポリウレア化合物ではない比較例２の試験グリースでは、基油の蒸発量がやや多く、焼付き寿命が特に悪くなっている。また、基油及び増ちょう剤とも本発明を満足しない比較例３の試験グリースでは、焼付き寿命も短く、低温での異音も発生し、更には基油の蒸発も多く、総合的な潤滑性能に劣っている。
【００３６】
【発明の効果】
以上説明したように、本発明のグリース組成物を封入することにより、軸受の焼付き寿命を向上させ、低温での異音の発生を抑えることができ、特に高温、高速、高荷重及び高振動下での使用に好適な転がり軸受が得られる。
【図面の簡単な説明】
【図１】本発明の転がり軸受の一実施形態を示す断面図である。
【図２】実施例において、付き寿命試験及び低温異音試験に用いた試験装置を示す概略断面図である。
【符号の説明】
１　玉軸受
１０　内輪
１１　外輪
１２　保持器
１３　玉
１４　シール[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is particularly suitable for use under high temperature, high speed, high load and high vibration, such as electric components of automobiles, alternators and intermediate pulleys as auxiliary equipment of air conditioners, electromagnetic clutches for car air conditioners, etc., and excellent seizure. The present invention relates to a rolling bearing having a long life and suppressing generation of abnormal noise at low temperatures, and a grease composition suitable for the rolling bearing.
[0002]
[Prior art]
Rolling bearings are generally used in electrical components of automobiles, alternators and intermediate pulleys as auxiliary equipment of air conditioners, electromagnetic clutches for car air conditioners, and the like, and a grease composition is sealed for lubrication.
[0003]
On the other hand, the spread of FF (Front Engine Front Drive) vehicles for the purpose of reducing the size and weight of automobiles, and the demand for more interior space has necessitated a reduction in the volume of the engine room. This has spurred the miniaturization and weight reduction of engine accessories. In addition, these components are also required to have high performance and high output.
[0004]
However, output reduction due to miniaturization is inevitable.For example, in the case of alternators and electromagnetic clutches for car air conditioners, the increase in output speed is compensated for by the increase in output speed. As the temperature inside the engine room becomes high, the rolling bearings used for these components are also required to have high-temperature durability. Furthermore, the sealing of the engine room is also progressing to improve quietness, and the temperature of the engine room is promoted, so the rolling bearings used for these parts need to have higher durability at higher temperatures. It is becoming.
[0005]
Also, in cold regions, when the engine is started, abnormal noise may be generated due to insufficient fluidity of the lubricant, and it is also required that no abnormal noise is generated at this low temperature. Lubricity in a wide temperature range up to high temperatures is required.
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and is suitable for use under high temperature, high speed, high load and high vibration, has an excellent seizure life, and is capable of generating abnormal noise at low temperature. An object of the present invention is to provide a reduced rolling bearing and a grease composition suitable for the rolling bearing.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a grease composition characterized in that a polyurea compound is compounded as a thickener in a base oil containing an alkyl-substituted diphenyl sulfide, and a grease composition between an inner ring and an outer ring. The present invention provides a rolling bearing characterized in that a plurality of rolling elements are rotatably held therein and the grease composition is sealed therein.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
[0009]
(Grease composition)
The base oil of the grease composition of the present invention contains an alkyl-substituted diphenyl sulfide. As the alkyl-substituted diphenyl sulfide, those represented by the following general formula (I) are preferable.
[0010]
Embedded image

[0011]
In the formula, R ¹ and R ² are a hydrocarbon group having 10 to 20 carbon atoms, and R ¹ and R ² may be the same or different from each other. M and n each represent an integer of 0 or more that satisfies 1 ≦ (m + n) ≦ 4. In particular, an alkyl-substituted diphenylsulfide in which R ¹ and R ² in the general formula (I) are a hydrocarbon group having 12 or 14 carbon atoms is preferable.
[0012]
Polyphenyl ether, silicone oil, fluorine oil and the like are known as base oils having excellent heat resistance, but polyphenylene ether oil and fluorine oil are very expensive, and silicone oil generally has the disadvantage of poor lubricity. . On the other hand, the alkyl-substituted diphenyl sulfide used in the present invention has the advantage of being excellent in heat resistance and lubricity, and also excellent in oxidation resistance and wear resistance, while being inexpensive.
[0013]
The alkyl-substituted diphenyl sulfide can independently constitute a base oil, but may be mixed with another lubricating oil so as to account for 30% by mass or more, preferably 40% by mass or more of the total amount of the base oil. When the content of the alkyl-substituted diphenylsulfide is less than 30% by mass of the total amount of the base oil, properties such as heat resistance, lubricity, oxidation resistance, and abrasion resistance may not be sufficiently exhibited.
[0014]
As the lubricating oil used for mixing, a lubricating oil having excellent heat resistance and oxidation resistance is preferable, and specifically, synthetic hydrocarbon oil, ether oil, and ester oil are preferable. Examples of the synthetic hydrocarbon oils include poly-α-olefin oils and the like. Examples of the ether oils include dialkyl diphenyl ether oils, alkyl triphenyl ether oils, and alkyl tetraphenyl ethers. The ester oils include diester oils and neopentyl type oils. Examples thereof include polyol ester oils, complex ester oils thereof, and aromatic ester oils. These lubricating oils may be used alone or in combination of two or more. Considering the improvement of lubrication performance and seizure life under high temperature, high speed, high load and high vibration, and suppression of abnormal sound generation at cryogenic temperature, ester oils, especially pentaerythritol ester and dipentaerythritol ester And the like, polyol ester oils, aromatic ester oils and synthetic hydrocarbon oils.
[0015]
The base oil composed as described above is, in reducing the bearing starting torque at low temperature, 20 to 200 mm ² / s at a kinematic viscosity at 40 ° C., particularly preferably from 40~150mm ² / s, other It is adjusted to this kinematic viscosity range by combination with a lubricating oil.
[0016]
On the other hand, as the polyurea compound used as a thickener, diurea, triurea, tetraurea or a polyurea compound having a higher molecular weight can be used, and a diurea compound represented by the following general formula (II) is particularly preferable.
R ³ —NHCONH—R ⁴ —HNOCHN—R ⁵ (II)
[0017]
In the formula, R ⁴ represents an aromatic hydrocarbon group having 6 to 15 carbon atoms, and R ³ and R ⁵ represent a hydrocarbon group or a condensed hydrocarbon group, which may be the same or different. In R ³ and R ⁵ , the hydrocarbon group may be any of an aliphatic hydrocarbon group and an aromatic hydrocarbon group, and the condensed hydrocarbon group preferably has 9 to 19 carbon atoms.
[0018]
The diurea compound represented by the general formula (II) has a ratio of a total of 2 mols of monoamine containing R ³ or R ⁵ in the skeleton to 1 mol of diisocyanate containing R ⁴ in the skeleton in the base oil. By reacting with
[0019]
As the diisocyanate containing R ⁴ in the skeleton, diphenylmethane diisoanate, tolylene diisocyanate, xylylene diisocyanate, biphenylene diisocyanate, dimethyl diphenylene diisocyanate, or an alkyl-substituted product thereof can be preferably used.
[0020]
Monoamines containing a hydrocarbon group in the skeleton as R ³ or R ⁵ 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, Amylcyclohexylamine, cyclooctylamine, benzylamine, benzhydrylurea Emissions, phenethylamine, methyl benzylamine, biphenyl amine, phenyl isopropylamine, can be suitably used phenylhexylamine like.
[0021]
Examples of the monoamine containing a condensed hydrocarbon group in the skeleton as R ³ or R ⁵ include indene-based amine compounds such as aminoindene, aminoindane, amino-1-methyleneindene, aminonaphthalene (naphthylamine), aminomethylnaphthalene, aminoethyl Naphthalene, aminodimethylnaphthalene, aminocadalene, aminovinylnaphthalene, aminophenylnaphthalene, aminobenzylnaphthalene, aminodinaphthylamine, aminobinaphthyl, amino-1,2-dihydronaphthalene, amino-1,4-dihydronaphthalene, aminotetrahydronaphthalene, amino Naphthalene amino compounds such as octalin, condensed bicyclic amine compounds such as aminopentalene, aminoazulene and aminoheptalene, aminofluorene, amino-9-phenyl Aminofluorene amine compounds such as fluorene, aminoanthracene, aminomethylanthracene, aminodimethylanthracene, aminophenylanthracene, anthracene amine compounds such as amino-9,10-dihydroanthracene, aminophenanthrene, amino-1,7-dimethylphenanthrene Phenanthrene amine compounds such as aminoretene, aminobiphenylene, amino-s-indacene, amino-as-indacene, aminoacenaphthylene, aminoacenaphthene, condensed tricyclic amine compounds such as aminophenalene, aminonaphthacene, amino Chrysene, aminopyrene, aminotriphenylene, aminobenzoanthracene, aminoascentrylene, aminoaceantrene, aminoacephenanthrylene, aminoacefena Condensed tetracyclic amine compounds such as nthrene, aminofluoranthene and aminopreaden; condensed pentacyclic amine compounds such as aminopentacene, aminopentaphene, aminopicene, aminoperylene, aminodibenzoanthracene, aminobenzopyrene and aminocholanthrene; Condensed polycyclic (six or more ring) amine compounds such as aminocoronene, aminopyranthrene, aminobiolanthrene, aminoisobiolanthrene, and aminoovalene are preferably used.
[0022]
The thickener comprising the polyurea compound is blended so as to be 5 to 40% by mass of the total amount of the grease composition. If the amount is less than 5% by mass, it is difficult to maintain the grease state. If the amount exceeds 40% by mass, the grease hardens excessively and cannot exert a sufficient lubricating effect. Considering that it can be used under high temperature, high speed, high load and high vibration, considering the softening of grease by high temperature and high shear, and the lubrication effect, the compounding amount of the thickener is 10 to 30 mass % Is preferable.
[0023]
Further, in the grease composition of the present invention, various additives may be added as required in order to further improve various performances thereof. Examples of the additive include, but are not limited to, amine-based, phenol-based, sulfur-based, antioxidants such as zinc dithiophosphate, zinc dithiocarbamate, metal sulfonates, esters, amines, and metal naphthenates. Rust inhibitors such as succinic acid derivatives, phosphorus-based, extreme pressure agents such as zinc dithiophosphate, organic molybdenum, fatty acids, oiliness improvers such as animal and vegetable oils, metal deactivators such as benzotriazole, etc., alone or appropriately. They can be used in combination. The amounts of these additives are not particularly limited as long as the objects of the present invention are not impaired.
[0024]
Further, the penetration consistency of the grease composition of the present invention is determined by NLGI No. 1 to No. 3 is preferred.
[0025]
(Rolling bearing)
The present invention also provides a rolling bearing enclosing the above grease composition. However, as the rolling bearing, for example, a ball bearing 1 as shown in FIG. 1 can be exemplified. That is, a plurality of balls 13 as rolling elements are rotatably held between the inner ring 10 and the outer ring 11 via the retainer 12, and a bearing space S formed by the inner ring 10, the outer ring 11, and the balls 13. , A predetermined amount of the above-described grease composition (not shown) is sealed therein and sealed with a seal 14.
[0026]
The rolling bearing of the present invention has a good lubricating effect even under high temperature, high speed, high load and high vibration as described above. It is suitable for use in pulleys, electromagnetic clutches for car air conditioners, and the like.
[0027]
【Example】
Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
[0028]
(Examples 1 to 7, Comparative Examples 1 to 3)
A test grease was prepared by mixing a thickener with a base oil as shown in Table 1. In each test grease, the compounding amount of the thickener was fixed, and a certain amount of an antioxidant and a rust inhibitor were added. An example of a method for preparing a test grease in the examples is as follows.
[0029]
That is, after dissolving diphenylmethane-4,4-diisocyanate in an alkyl-substituted diphenylsulfide as a base oil, the same as that obtained by dissolving stearylamine in the same base oil while heating to about 70 ° C. Add a solution of cyclohexylamine in the base oil, stir and react, then heat to 130 ° C to complete the reaction, add a predetermined amount of antioxidant and rust inhibitor, mill and defoam. By doing so, a test grease was obtained.
[0030]
Each test grease was subjected to the following (1) seizure test, (2) low temperature abnormal noise test, and (3) evaporative loss test.
[0031]
(1) Seizure test A test grease is filled in a deep groove ball bearing with a contact rubber seal with the structure shown in Fig. 1 having an inner diameter of 25 mm, an outer diameter of 62 mm, and a width of 17 mm so as to occupy 30% by volume of the bearing space (S). Thus, a test bearing was manufactured. The test was performed using the test device shown in FIG. The illustrated test apparatus supports a rotating shaft 20 with a pair of supporting bearings 22, 22, mounts a test bearing 21 in an intermediate portion thereof, and further maintains a constant temperature vessel (not shown) so that the whole can be maintained at a predetermined temperature. ). In the test, the shaft 20 was rotated, and the test bearing 21 was continuously rotated under the conditions of an inner ring rotation speed of 10000 min ^-1 , a bearing outer ring temperature of 180 ° C., a radial load of 1470 N, and an axial load of 98 N. The test was terminated when the temperature rose to ℃ or more, and when the rotational torque sharply increased, and the time until that was measured. The test was performed for each of four cases, and the results are also shown in Table 1 in terms of relative values with the seizure time of the test bearing in which the test grease of Comparative Example 1 was encapsulated as 1.
[0032]
(2) Low-temperature abnormal noise test The same test bearings as those used in the above-mentioned seizure test were prepared, and the same test equipment was used under the conditions of an inner ring rotation speed of 1800 min- ¹ , a bearing outer ring temperature of -20 ° C, and an axial load of 98N. Then, the test bearing was continuously rotated to confirm the occurrence of abnormal noise. The results are shown in Table 1.
[0033]
(3) Evaporation Weight Loss Test 15 mg of test grease was sampled, and the weight loss when held at 160 ° C. for 12 hours was measured by thermogravimetric analysis (TGA). The results are shown in Table 1.
[0034]
[Table 1]

[0035]
As is clear from Table 1, according to the present invention, a grease composition in which a polyurea compound is added as a thickener to a base oil containing an alkyl-substituted diphenyl sulfide improves the seizure life of the bearing, It can be seen that no abnormal noise is generated, the amount of base oil evaporated is small, and the lubrication performance can be maintained for a long time. On the other hand, in the test grease of Comparative Example 1 in which the base oil does not contain an alkyl-substituted diphenyl sulfide, the seizing life and the evaporation of the base oil are large, and the effect of improving the durability of the bearing is small. Further, in the test grease of Comparative Example 2 in which the thickener was not a polyurea compound, the amount of evaporation of the base oil was slightly large, and the seizure life was particularly poor. The test grease of Comparative Example 3 in which neither the base oil nor the thickener satisfies the present invention has a short seizure life, generates abnormal noise at low temperatures, further evaporates the base oil, and provides comprehensive lubrication. Poor performance.
[0036]
【The invention's effect】
As described above, by enclosing the grease composition of the present invention, it is possible to improve the seizure life of the bearing and suppress the generation of abnormal noise at low temperatures, particularly at high temperatures, high speeds, high loads and high vibrations. A rolling bearing suitable for use below is obtained.
[Brief description of the drawings]
FIG. 1 is a sectional view showing one embodiment of a rolling bearing of the present invention.
FIG. 2 is a schematic cross-sectional view showing a test apparatus used for an endurance life test and a low-temperature abnormal noise test in Examples.
[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 base oil containing an alkyl-substituted diphenyl sulfide and a polyurea compound as a thickener. An alkyl-substituted diphenyl sulfide is contained in an amount of 30% by mass or more based on the total amount of the base oil, and a thickener comprising a polyurea compound is contained in an amount of 5 to 40% by mass based on the total amount of the grease composition. Item 3. The grease composition according to Item 1. A rolling bearing comprising a plurality of rolling elements rotatably held between an inner ring and an outer ring, wherein the grease composition according to claim 1 or 2 is sealed therein.

Images