JP4709412B2 - Grease composition for high-speed cleaner bearings - Google Patents
Grease composition for high-speed cleaner bearings Download PDFInfo
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- JP4709412B2 JP4709412B2 JP2001109634A JP2001109634A JP4709412B2 JP 4709412 B2 JP4709412 B2 JP 4709412B2 JP 2001109634 A JP2001109634 A JP 2001109634A JP 2001109634 A JP2001109634 A JP 2001109634A JP 4709412 B2 JP4709412 B2 JP 4709412B2
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- Prior art keywords
- grease composition
- mass
- bearing
- cleaner
- speed
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Description
【0001】
【発明の属する技術分野】
本発明は、高速クリーナー軸受用グリース組成物、特に5万rpm以上で回転する高速クリーナー軸受用グリース組成物に関するものである。
【0002】
【従来の技術】
従来、5万rpm以下の回転で用いられるクリーナー用軸受では、回転数が低いためトルクや寿命に対し問題となることはなかった。しかし、クリーナーの高効率化のために吸引力を上げる必要から、回転数が5万rpmあるいは6万rpmと向上してきた。同時に省エネルギーの観点から消費電力低減のため低トルクであることも要求され、さらには製品の寿命の延長も要求されるようになってきた。このような用途に使用される高速クリーナー軸受への様々な要求に対し、従来のグリース組成物では回転トルクが上昇したり、グリース組成物が遠心力下で飛散漏洩し、軸受寿命が短くなるなどの問題を抱えていた。
【0003】
【発明が解決しようとする課題】
本発明の目的は、高速クリーナー軸受用グリース組成物、特に5万rpm以上で回転する高速クリーナー軸受用グリース組成物を提供することである。
本発明の他の目的は、5万rpm以上の高速クリーナー軸受に用いられるグリース組成物であって、回転トルクが低く、グリース組成物の漏洩量が少なく、軸受寿命が長いグリース組成物を提供することである。
【0004】
【課題を解決するための手段】
本発明は、40℃における動粘度が50〜70mm2/sであり、かつ炭素原子数28〜32の炭化水素分子を3〜6質量%含有する合成炭化水素油の基油と増ちょう剤を含むことを特徴とする高速クリーナー軸受用グリース組成物を提供するものである。
【0005】
【発明の実施の形態】
本発明は、基油として、40℃における動粘度が50〜70mm2/sである合成炭化水素油を使用する。合成炭化水素油の動粘度が50mm2/s未満では、5万rpm以上の回転数においてグリース組成物が飛散、漏洩し、軸受寿命が短くなってしまい、また、70mm2/sを越えると、軸受の回転トルクが上昇し、エネルギーロスが生じるという点で好ましくない。
本発明に使用する合成炭化水素油は、炭素原子数28〜32の炭化水素分子を3〜6質量%含有するものである。炭素原子数28〜32の炭化水素分子の含有量が3質量%未満では、回転数が高くなるとトルクが高くなり、特に5万rpm以上では極めて高くなる。また炭素原子数28〜32の炭化水素分子の含有量が6質量%を越えると、グリース組成物の漏洩量が多くなり、軸受寿命が短くなる。
【0006】
本発明に使用する合成炭化水素油は、炭素原子数48以上の炭化水素分子を70質量%以上含有するものが好ましい。本発明に使用する合成炭化水素油の主成分は炭素原子数48以上の炭化水素分子であり、合成炭化水素油中の含有量は70〜85質量%である。
本発明に使用する合成炭化水素油は、市販の各種ポリαオレフィン(PAO)を上記の条件を満足するように適宜混合することにより調製できる。
本発明のグリース組成物中、上記合成炭化水素油の含有量は、好ましくは75〜95質量%、さらに好ましくは80〜90質量%である。
【0007】
本発明のグリース組成物に使用される増ちょう剤は、ウレア系増ちょう剤であることが好ましく、特に1分子中に2個のウレア結合を有するジウレア化合物が好ましい。ジウレア化合物のうち、末端基が脂肪族又は脂環式であるジウレア化合物が好適である。
本発明のグリース組成物中、増ちょう剤は目的とするグリース組成物のちょう度に合わせて使用されるが、その含有量は通常8〜18質量%程度である。
【0008】
本発明のグリース組成物には、一般的にグリース組成物に配合される、酸化防止剤、極圧剤、防錆剤、腐食防止剤、油性剤等を含有させてもよい。
酸化防止剤としては、フェノール系や芳香族アミン系の化合物が挙げられる。例えば、2,6-ジ-t-ブチル-4-メチルフェノールなどのフェノール系酸化防止剤;p、p'-ジオクチルジフェニルアミンなどのアミン系酸化防止剤等があげられる。これらの酸化防止剤は、それぞれ単独で又は2種以上を混合して用いることができる。本発明のグリース組成物中、これらの酸化防止剤の量は0.5〜5質量%が適当である。
本発明のグリース組成物は従来公知の方法により製造することができる。
【0009】
【実施例及び比較例】
増ちょう剤として脂環−脂肪族混合のジウレア化合物(ジフェニルメタン4,4´−ジイソシアネート5モル、シクロヘキシルアミン3モル、ステアリルアミン7モルのモル比で反応させたジウレア化合物)14質量%、アミン系酸化防止剤2.5質量%、スルホン酸系及びエステル系防錆剤2.0質量%、粘度調整のための粘度向上剤(ブチル系ポリマー)を適量、残部が表1に示す組成の合成炭化水素油、を使用して、グリース組成物を調製した。グリース組成物のちょう度は比較例2のグリース組成物を210とした他はすべて230とした。グリース組成物の特性を以下の試験方法により測定し評価した。
【0010】
トルク試験方法
軸受(呼び番号608)にグリース組成物を130mg充填し、アキシャル方向に3.9kgfの与圧を与え、内輪を60000rpmで回転させたとき、外輪を静止させる荷重を測定し、トルクとする。
漏洩量試験方法
軸受(呼び番号608)にグリース組成物を130mg充填し、アキシャル方向に3.9kgfの与圧を与え、140℃×20000rpm×150時間連続回転させる。試験後測定した軸受の重量減を、グリース組成物漏洩量として算出する。
寿命試験方法
軸受(呼び番号608)にグリース組成物を130mg充填し、アキシャル方向に3.9kgfの与圧を与え、室温×60000rpmで連続回転させる。試験中過負荷によりモーター電流値が設定値を越えた時間を、このグリース組成物の潤滑寿命時間とする。
結果を表1に示す。
【0011】
【表1】
【0012】
表1に示すように、基油として、40℃における動粘度が50〜70mm2/sであり、かつ炭素原子数28〜32の炭化水素分子を3〜6質量%含有する合成炭化水素油を用いた実施例1及び2のグリース組成物では、高速回転においてもトルクが低く、グリース組成物の漏洩量も少なく、軸受寿命は長い。
これに対して、基油として、炭素原子数28〜32の炭化水素分子を14質量%含有し、その動粘度が50mm2/s未満である合成炭化水素油を用いた比較例1のグリース組成物では、高速回転におけるトルクは低いものの、グリース組成物の漏洩量が多く、軸受寿命が短い。比較例1において、ちょう度を210と硬くした比較例2のグリース組成物では、高速回転におけるトルクは低いものの、グリース組成物の漏洩量が多く、軸受寿命が短い。
【0013】
比較例1又は2と同じ基油において、ブチル系ポリマーを添加して40℃の動粘度を50mm2/sに上げた比較例3のグリース組成物では、高速回転におけるトルクは低いものの、グリース組成物の漏洩量が多く、軸受寿命が短い。
炭素原子数28〜32の炭化水素分子を7質量%含有し、その動粘度が50mm2/s未満の合成炭化水素油を用いた比較例4のグリース組成物では、高速回転におけるトルクは低いものの、グリース組成物の漏洩量が多く、軸受寿命が短い。
炭素原子数28〜32の炭化水素分子を4質量%含有しているが、その動粘度が50mm2/s未満の合成炭化水素油を用いた比較例5のグリース組成物では、高速回転におけるトルクは低いものの、グリース組成物の漏洩量が多く、軸受寿命が短い。
動粘度が50〜70mm2/sであるが、炭素原子数28〜32の炭化水素分子の含有量が4質量%未満の合成炭化水素油を用いた比較例6及び7のグリース組成物では、グリース組成物の漏洩量が少なく、軸受寿命も長いが、高速回転におけるトルクが高い。
【0014】
以上の結果は、高速回転においてもトルクが低く、グリース組成物の漏洩量が少なく、軸受寿命が長いグリース組成物を製造するためには、基油として、40℃における動粘度が50〜70mm2/sであり、かつ炭素原子数28〜32の炭化水素分子を3〜6質量%含有する合成炭化水素油を用いることが必要であることを示している。
【0015】
【発明の効果】
本発明のグリース組成物は、軸受に用いられた場合に、回転トルクが低く、グリース組成物の漏洩量が少なく、軸受寿命が長いという効果を奏する。特に5万rpm以上で回転するクリーナーの軸受に用いられた場合に、その効果は特に顕著である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a grease composition for a high-speed cleaner bearing, and more particularly to a grease composition for a high-speed cleaner bearing that rotates at 50,000 rpm or more.
[0002]
[Prior art]
Conventionally, a cleaner bearing used at a rotation speed of 50,000 rpm or less has no problem with respect to torque and life due to a low rotation speed. However, the rotational speed has been improved to 50,000 rpm or 60,000 rpm because it is necessary to increase the suction force in order to increase the efficiency of the cleaner. At the same time, from the viewpoint of energy saving, low torque is also required to reduce power consumption, and further extension of product life has been required. In response to various requirements for high-speed cleaner bearings used in such applications, conventional grease compositions increase rotational torque, or grease compositions scatter and leak under centrifugal force, shortening bearing life, etc. Had a problem with.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to provide a grease composition for a high-speed cleaner bearing, particularly a grease composition for a high-speed cleaner bearing that rotates at 50,000 rpm or more.
Another object of the present invention is to provide a grease composition used for a high-speed cleaner bearing of 50,000 rpm or more, which has a low rotational torque, a small amount of leakage of the grease composition, and a long bearing life. That is.
[0004]
[Means for Solving the Problems]
The present invention relates to a base oil and a thickener of a synthetic hydrocarbon oil having a kinematic viscosity at 40 ° C. of 50 to 70 mm 2 / s and containing 3 to 6% by mass of a hydrocarbon molecule having 28 to 32 carbon atoms. The present invention provides a grease composition for high-speed cleaner bearings.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, a synthetic hydrocarbon oil having a kinematic viscosity at 40 ° C. of 50 to 70 mm 2 / s is used as the base oil. When the kinematic viscosity of the synthetic hydrocarbon oil is less than 50 mm 2 / s, the grease composition scatters and leaks at a rotational speed of 50,000 rpm or more, shortening the bearing life, and when exceeding 70 mm 2 / s, This is not preferable in that the rotational torque of the bearing increases and energy loss occurs.
The synthetic hydrocarbon oil used in the present invention contains 3 to 6% by mass of hydrocarbon molecules having 28 to 32 carbon atoms. When the content of hydrocarbon molecules having 28 to 32 carbon atoms is less than 3% by mass, the torque increases as the rotational speed increases, and particularly increases at 50,000 rpm or higher. On the other hand, when the content of hydrocarbon molecules having 28 to 32 carbon atoms exceeds 6% by mass, the leakage amount of the grease composition increases and the bearing life is shortened.
[0006]
The synthetic hydrocarbon oil used in the present invention preferably contains 70% by mass or more of hydrocarbon molecules having 48 or more carbon atoms. The main component of the synthetic hydrocarbon oil used in the present invention is a hydrocarbon molecule having 48 or more carbon atoms, and the content in the synthetic hydrocarbon oil is 70 to 85% by mass.
The synthetic hydrocarbon oil used in the present invention can be prepared by appropriately mixing various commercially available poly α-olefins (PAO) so as to satisfy the above conditions.
In the grease composition of the present invention, the content of the synthetic hydrocarbon oil is preferably 75 to 95% by mass, more preferably 80 to 90% by mass.
[0007]
The thickener used in the grease composition of the present invention is preferably a urea-based thickener, and particularly preferably a diurea compound having two urea bonds in one molecule. Of the diurea compounds, diurea compounds whose terminal groups are aliphatic or alicyclic are preferred.
In the grease composition of the present invention, the thickener is used according to the consistency of the intended grease composition, but the content thereof is usually about 8 to 18% by mass.
[0008]
The grease composition of the present invention may contain an antioxidant, an extreme pressure agent, a rust inhibitor, a corrosion inhibitor, an oily agent and the like that are generally blended in the grease composition.
Antioxidants include phenolic and aromatic amine compounds. Examples thereof include phenolic antioxidants such as 2,6-di-t-butyl-4-methylphenol; amine antioxidants such as p, p′-dioctyldiphenylamine and the like. These antioxidants can be used alone or in admixture of two or more. In the grease composition of the present invention, the amount of these antioxidants is suitably 0.5 to 5% by mass.
The grease composition of the present invention can be produced by a conventionally known method.
[0009]
[Examples and Comparative Examples]
As a thickener, 14% by mass of an alicyclic-aliphatic mixed diurea compound (diurea compound reacted at a molar ratio of 5 mol of diphenylmethane 4,4'-diisocyanate, 3 mol of cyclohexylamine and 7 mol of stearylamine), amine-based oxidation 2.5% by mass of an inhibitor, 2.0% by mass of a sulfonic acid-based and ester-based rust preventive, an appropriate amount of a viscosity improver (butyl-based polymer) for adjusting viscosity, and the balance is a synthetic hydrocarbon having the composition shown in Table 1. A grease composition was prepared using oil. The consistency of the grease composition was 230 except that the grease composition of Comparative Example 2 was 210. The properties of the grease composition were measured and evaluated by the following test methods.
[0010]
Torque test method A bearing (nominal number 608) was filled with 130 mg of the grease composition, a pressure of 3.9 kgf was applied in the axial direction, and when the inner ring was rotated at 60000 rpm, the load that caused the outer ring to stop was measured. To do.
Leakage amount test method A bearing (nominal number 608) is filled with 130 mg of the grease composition, a pressure of 3.9 kgf is applied in the axial direction, and the bearing is continuously rotated at 140 ° C. × 20000 rpm × 150 hours. The weight loss of the bearing measured after the test is calculated as the grease composition leakage amount.
Life test method A bearing (nominal number 608) is filled with 130 mg of the grease composition, a pressure of 3.9 kgf is applied in the axial direction, and the bearing is continuously rotated at room temperature × 60000 rpm. The time during which the motor current value exceeds the set value due to overload during the test is defined as the lubrication life time of the grease composition.
The results are shown in Table 1.
[0011]
[Table 1]
[0012]
As shown in Table 1, as a base oil, a synthetic hydrocarbon oil having a kinematic viscosity at 40 ° C. of 50 to 70 mm 2 / s and containing 3 to 6% by mass of a hydrocarbon molecule having 28 to 32 carbon atoms is used. In the grease compositions of Examples 1 and 2 used, the torque is low even at high speed rotation, the leakage amount of the grease composition is small, and the bearing life is long.
In contrast, the grease composition of Comparative Example 1 using a synthetic hydrocarbon oil containing 14% by mass of hydrocarbon molecules having 28 to 32 carbon atoms and having a kinematic viscosity of less than 50 mm 2 / s as the base oil. Although the torque at high speed rotation is low, the amount of leakage of the grease composition is large and the bearing life is short. In Comparative Example 1, the grease composition of Comparative Example 2 with a consistency of 210, which is hard, has a low torque at high speed rotation, but has a large amount of leakage of the grease composition and a short bearing life.
[0013]
In the same base oil as in Comparative Example 1 or 2, in the grease composition of Comparative Example 3 in which a butyl polymer was added and the kinematic viscosity at 40 ° C. was increased to 50 mm 2 / s, although the torque at high speed rotation was low, the grease composition Large amount of material leakage and short bearing life.
In the grease composition of Comparative Example 4 using a synthetic hydrocarbon oil containing 7% by mass of hydrocarbon molecules having 28 to 32 carbon atoms and having a kinematic viscosity of less than 50 mm 2 / s, the torque at high speed rotation is low. The amount of leakage of the grease composition is large and the bearing life is short.
In the grease composition of Comparative Example 5 using a synthetic hydrocarbon oil containing 4% by mass of hydrocarbon molecules having 28 to 32 carbon atoms and having a kinematic viscosity of less than 50 mm 2 / s, torque at high speed rotation Is low, but the leakage amount of the grease composition is large and the bearing life is short.
In the grease compositions of Comparative Examples 6 and 7 using a synthetic hydrocarbon oil having a kinematic viscosity of 50 to 70 mm 2 / s but a hydrocarbon molecule content of 28 to 32 carbon atoms of less than 4% by mass, The amount of leakage of the grease composition is small and the bearing life is long, but the torque at high speed rotation is high.
[0014]
The above results show that a kinematic viscosity at 40 ° C. is 50 to 70 mm 2 as a base oil in order to produce a grease composition having a low torque even at high speed rotation, a small amount of leakage of the grease composition, and a long bearing life. / S and it is necessary to use a synthetic hydrocarbon oil containing 3 to 6% by mass of hydrocarbon molecules having 28 to 32 carbon atoms.
[0015]
【The invention's effect】
When used in a bearing, the grease composition of the present invention has an effect that the rotational torque is low, the amount of leakage of the grease composition is small, and the bearing life is long. The effect is particularly remarkable when used for a cleaner bearing rotating at 50,000 rpm or more.
Claims (4)
Priority Applications (1)
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JP2001109634A JP4709412B2 (en) | 2001-04-09 | 2001-04-09 | Grease composition for high-speed cleaner bearings |
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JP2001109634A JP4709412B2 (en) | 2001-04-09 | 2001-04-09 | Grease composition for high-speed cleaner bearings |
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JP2002309278A JP2002309278A (en) | 2002-10-23 |
JP4709412B2 true JP4709412B2 (en) | 2011-06-22 |
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JP2001109634A Expired - Lifetime JP4709412B2 (en) | 2001-04-09 | 2001-04-09 | Grease composition for high-speed cleaner bearings |
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JP2000120700A (en) * | 1998-10-16 | 2000-04-25 | Nsk Ltd | Ball bearing for motor of electric vacuum cleaner |
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