JP2005112955A - Grease composition and rolling apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grease composition which has excellent grease fluidity under conditions especially at high temperatures and at high speeds, has a long life even at high temperatures and is useful for a rolling apparatus or the like. <P>SOLUTION: The grease composition containing a base oil and a urea compound as a thickener, is characterized in that a nonpolar wax, a polar wax or a metallic soap is made to contain in an amount of 0.5-20 % by mass relative to the total amount of the grease composition. The rolling apparatus encloses the above grease composition. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a grease composition used for rolling devices and the like, and in particular, rotating parts and sleeves of equipment used at high temperature and high speed such as automotive electrical parts such as alternators and electromagnetic clutches, and automobile engine accessories such as idler pulleys. The present invention relates to a grease composition suitably used in a rolling device such as a rolling bearing used for a moving part, and a rolling device formed by sealing the grease composition.

  Automobiles are forced to reduce the engine room space due to demands for smaller size and lighter living space, and further miniaturization of electrical components and engine accessories has been promoted. In addition, since the sealing of the engine room is progressed due to a demand for improvement in quietness and the high temperature in the engine room is promoted, it is also important that each of the above components can withstand high temperatures. For example, the bearings used in these electrical applications have been conventionally used at a bearing temperature of 130 to 150 ° C., but recently, bearings that can withstand high temperatures of 160 to 200 ° C. are required. Therefore, grease with higher heat resistance is required at a high temperature of 160 ° C. or higher.

  Japanese Patent 2764724, Japanese Patent Laid-Open No. 5-98280, and Japanese Patent 3337593 (in order, Patent Documents 1, 2 and 3) are mainly alkyldiphenyl ether oil as a base oil and terminal as a thickener. However, grease compositions using urea compounds mainly composed of aromatic hydrocarbon groups are seized early under high temperature and high speed conditions due to insufficient fluidity at high temperatures.

Also, a grease composition disclosed in Japanese Patent No. 2979274 (Patent Document 4) using a urea compound mainly composed of alkyldiphenyl ether oil as a base oil and terminally composed of a cyclohexyl group as a thickener is used at a high temperature. Due to softening, there are many leaks and seizure occurs early.
Japanese Patent No. 2764724 Japanese Patent Laid-Open No. 5-98280 Japanese Patent No. 3337593 Japanese Patent No. 2979274

  The problem to be solved by the present invention is a problem of the above-described conventional technology.

  Therefore, an object of the present invention is to provide a grease composition that has excellent grease fluidity particularly under high temperature and high speed conditions, has a long life even under high temperature, and is useful for a rolling device or the like.

  In order to solve the above-mentioned problems, the present invention provides a grease composition having the following configuration. That is, according to the present invention, in a grease composition containing a base oil and a urea compound as a thickener, nonpolar wax, polar wax or metal soap is contained in an amount of 0.5 to 20% by mass in the total amount of the grease composition. A grease composition is provided.

  The present invention also provides a rolling device in which the grease composition is enclosed.

  Since the grease composition of the present invention has the above-described configuration, the degree of curing is low even at high temperatures, and particularly has excellent grease fluidity under high temperature and high speed conditions. There is an effect that it is useful for the above. Moreover, since the rolling device of this invention consists of the structure formed by enclosing the said grease composition, there exists an effect that high temperature durability and peelability improve.

[Grease composition]
Hereinafter, the grease composition of the present invention will be described in detail based on preferred embodiments thereof.

  As described above, the grease composition of the present invention contains a base oil and a diurea compound as a thickener, and contains a nonpolar wax, a polar wax or a metal soap in an amount of 0.5 to 20% by mass based on the total amount of the grease composition. It was made to be characterized.

  The grease composition of the present invention contains at least one nonpolar wax, polar wax or metal soap.

  Non-polar wax is a wax that does not have a polar group in the wax component. It is a petroleum wax extracted during petroleum refining, Fischer-Tropsch wax synthesized by reacting carbon monoxide and hydrogen, polymerization of ethylene, or heat of polyethylene. There are polyethylene waxes produced by decomposition, and in particular, polyolefin wax is preferably used because it is excellent in lubricity and can be obtained at low cost. More preferably, polyethylene wax is used.

  The polar wax is a wax having a polar group in the wax component. In particular, the polar group is adsorbed on the surface of the application target of the grease composition, thereby improving lubricity. Wax is preferred. Montan wax includes montanic acid wax obtained from lignite or lignite, fatty acid ester, fatty acid amide, ketone / amines and other solid substances at normal temperature, and montanic acid alkali metal salt wax, oxidized wax obtained by oxidizing wax, amide wax Preferably, a metal montanate salt wax is used, and an alkali metal montanate salt wax is more preferably used.

  Moreover, as a metal soap, lithium soap can be used conveniently. In particular, 12-hydroxy lithium stearate or lithium stearate is preferable.

  The nonpolar wax, polar wax and metal soap used in the present invention each show good results, but preferably nonpolar wax and polar wax, nonpolar wax and metal soap, or three The effect is further enhanced by blending at the same time.

  In the grease composition of the present invention, the total content of nonpolar wax, polar wax and metal soap is 0.5 to 20% by weight, preferably 0.5 to 15% by weight, more preferably 1 -10% by weight. If it is less than 0.5% by weight, the effect is not exhibited, and if it exceeds 20% by weight, the grease composition is excessively cured and a sufficient lubricating effect cannot be exhibited.

  The base oil used in the grease composition of the present invention is not particularly limited, but a synthetic oil is preferable in consideration of use in a high-speed rolling bearing at a high temperature.

  As the synthetic oil, fluorine oil, silicon oil, ester oil, ether oil, synthetic hydrocarbon oil and the like can be used.

  Among the synthetic oils, it is preferable to contain an ester oil, particularly an aromatic ester oil, especially an alkyl ester of trimellitic acid or pyromellitic acid as a base oil component. In this case, the alkyl group is an alkyl group having 4 to 18 carbon atoms, specifically, butyl group, pentyl group, hexyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group. Tetradecyl group, hexadecyl group, heptadecyl group, octadecyl group and the like. These alkyl groups may be linear or branched.

  Moreover, as ester oil, polyol ester can also be used suitably, for example, pentaerythritol ester oil, specifically, trimethylolpropane caprylate, pentaerythritol-2-ethylhexanoate, etc. are mentioned.

  Furthermore, ether oil can also be preferably used as a synthetic oil. Examples of the ether oil include polyphenyl ether oil, diphenyl ether oil, and polyvinyl ether oil, and dialkyl diphenyl ether represented by the following general formula (I) or (II) is preferable.

なお、式（Ｉ）及び（II）中のＲ_５及びＲ_６は、同一又は異なる基であり、好ましくは炭素数８〜２０、さらに好ましくは炭素数１２〜１４の直鎖アルキル基である。

Incidentally, _{R 5} and _{R 6} in the formula (I) and (II) are identical or different radicals, preferably from 8 to 20 carbon atoms, more preferably a linear alkyl group having 12 to 14 carbon atoms.

  Of the synthetic hydrocarbon oils, poly-alpha olefin oils can be suitably used.

  Moreover, you may mix above-described oil as needed. For example, it is possible to mix one or more of aromatic ester oil, alkyl diphenyl ether oil, pentaerythritol oil, and polyalphaolefin oil. In that case, it is preferable that aromatic ester oil is contained as an essential component from a heat resistant durability viewpoint. Preferably, the mixing ratio is less than 100 parts by weight of other oils relative to 100 parts by weight of the aromatic ester oil, that is, the amount of the aromatic ester oil exceeds 50% by weight in the total amount of the base oil. When the aromatic ester oil is 50% by weight or less, the oxidation stability at high temperature is inferior and early seizure is likely to occur.

The base oil preferably has a kinematic viscosity at 40 ° C. of 30 to 200 mm ² / s. When the kinematic viscosity at 40 ° C. exceeds 200 mm ² / s, when the grease composition is used in a rolling device, the torque of the rolling device increases excessively, which is not preferable. Further, the fluidity at low temperature becomes insufficient, and there is a possibility that abnormal noise may be generated when the rolling device is started at a low temperature. If the kinematic viscosity at 40 ° C. of the base oil is less than 30 mm ² / s, it is not appropriate due to evaporation loss and lubricity problems. That is, if the viscosity of the base oil is too low, it becomes difficult to form a lubricating oil film sufficient to avoid metal contact between the raceway surface and the rolling element at high temperatures, for example, during rotation of the bearing. In order to make it difficult for such problems to occur, the kinematic viscosity at 40 ° C. of both is preferably 30 to 200 mm ² / s. However, since the grease composition of the present invention contains a wax (the aforementioned nonpolar wax or polar wax), it can form a stronger oil film than the base oil alone, so that the base oil viscosity is relatively low. It may be lower, more preferably 30 to 150 mm ² / s, and most preferably 30 to 90 mm ² / s.

  The urea compound as a thickener used in the grease composition of the present invention can be a diurea, triurea, tetraurea or higher polyurea compound. In particular, diurea represented by the following general formula (III) is preferable.

一般式（III）中、Ｒ_１、Ｒ_１は炭化水素基を表し、同一でも異なっていてもよい。また、Ｒ_１において炭化水素基は脂肪族炭化水素基、脂環式炭化水素基、芳香族炭化水素基の何れでもよい。Ｒ_１において、好ましい炭素数は、６〜２０である。Ｒ_２は炭素数が好ましくは６〜１５の芳香族炭化水素基を示す。

In general formula (III), R ₁ and R ₁ represent a hydrocarbon group, which may be the same or different. In R ₁ , the hydrocarbon group may be an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, or an aromatic hydrocarbon group. In R ₁ , a preferable carbon number is 6-20. R ₂ preferably represents an aromatic hydrocarbon group having 6 to 15 carbon atoms.

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

As the diisocyanate containing R ₂ in the skeleton, diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, biphenylene diisocyanate, dimethyl diphenylene diisocyanate, or alkyl-substituted products thereof can be suitably used.

The monoamine containing R ₁ or R ₁ in the backbone, with a monoamine containing a hydrocarbon group (. Excluding condensed ring hydrocarbon group) in the backbone as R ₁ or R _1, fused ring hydrocarbon as R ₁ or R ₁ Broadly divided into monoamines containing hydrogen groups in the skeleton.

Here, as monoamines containing a hydrocarbon group in the skeleton as R ₁ or R ₁ , aniline, cyclohexylamine, octylamine, toluidine, dodecylaniline, octadecylamine, hexylamine, heptylamine, nonylamine, ethylexylamine, decylamine , Undecylamine, dodecylamine, tetradecylamine, pentadecylamine, nonadecylamine, eicodecylamine, oleylamine, linoleylamine, linolenylamine, methylcyclohexylamine, ethylcyclohexylamine, dimethylcyclohexylamine, diethylcyclohexylamine, butylcyclohexylamine, Propylcyclohexylamine, amylcyclohexylamine, cyclooctylamine, benzylamine, benzhi Riruamin, phenethylamine, methyl benzylamine, biphenyl amine, phenyl isopropylamine, can be suitably used phenylhexylamine like.

On the other hand, as monoamines containing a condensed ring hydrocarbon group in the skeleton as R ₁ or R ₁ , for example, indene-based amine compounds such as aminoindene, aminoindane, amino-1-methyleneindene, aminonaphthalene (naphthylamine), aminomethyl, etc. Naphthalene, aminoethylnaphthalene, aminodimethylnaphthalene, aminocadalene, aminovinylnaphthalene, aminophenylnaphthalene, aminobenzylnaphthalene, aminodinaphthylamine, aminobinaphthyl, amino-1,2-dihydronaphthalene, amino-1,4-dihydronaphthalene, amino Naphthalene-based amino compounds such as tetrahydronaphthalene and aminooctalene, condensed bicyclic amine compounds such as aminopentalene, aminoazulene and aminoheptalene, aminofluorene, Aminofluorene-based amine compounds such as mino-9-phenylfluorene, aminoanthracene, aminomethylanthracene, aminodimethylanthracene, aminophenylanthracene, anthracene-based amine compounds such as amino-9,10-dihydroanthracene, aminophenanthrene, amino- Phenanthreneamine compounds such as 1,7-dimethylphenanthrene and aminoretene; condensed tricyclic amine compounds such as aminobiphenylene, amino-s-indacene, amino-as-indacene, aminoacenaphthylene, aminoacenaphthene and aminophenalene; Aminonaphthacene, aminochrysene, aminopyrene, aminotriphenylene, aminobenzoanthracene, aminoaceanthrylene, aminoaceanthrene, aminoacephena Condensed tetracyclic amine compounds such as N-tolylene, aminoacephenanthrene, aminofluoranthene, and aminopreadenene, and condensed pentacycles such as aminopentacene, aminopentaphene, aminopicene, aminoperylene, aminodibenzoanthracene, aminobenzopyrene, and aminocholanthrene Condensed polycyclic (six or more ring) amine compounds such as a series amine compound, amino coronene, amino pyranthrene, amino violanthrene, aminoisoviolanthrene and amino ovalen are preferably used.

  The grease composition of the present invention preferably has a miscibility of 220 to 385. When the penetration is less than 220, when applied to a rolling device, the grease composition is too hard, and the torque performance of the rolling device filled with the grease composition may be reduced. On the other hand, if the penetration is over 385, the amount of grease composition leaking from the rolling device may increase.

  In the grease composition of the present invention, there is no particular limitation as long as the above-mentioned blending degree can be obtained, but the content of the thickener is preferably 5 to 30% by weight of the whole grease composition. If it is less than 5% by weight, it is difficult to maintain the grease state, and if it is more than 30% by weight, the grease composition is too hard to exhibit sufficient lubricity. However, in consideration of the penetration of the grease composition and the rolling device filled with this grease, the content of the thickener is more preferably 10 to 25% by weight of the whole composition.

  Furthermore, in order to further improve various performances of the grease composition of the present invention, various additives may be mixed as desired. Examples of such additives include antioxidants, rust inhibitors, extreme pressure agents, oil agents, metal deactivators, and the like.

  Here, as the antioxidant, a commonly used antioxidant can be used. For example, an amine such as phenyl-1-naphthylamine, a phenol such as 2,6-di-tert-dibutylphenol, an antioxidant such as sulfur or zinc dithiophosphate can be used.

  Antirust agents include organic sulfonates such as alkali metals and alkaline earth metals, alkyls such as alkyl and alkenyl succinic acid esters, alkenyl succinic acid derivatives and partial esters of polyhydric alcohols such as sorbitan monooleate. Rust can be used.

  As the extreme pressure agent, an extreme pressure agent such as phosphorus-based, zinc dithiophosphate, or organic molybdenum can be used.

  Oiliness agents such as fatty acids and animal and vegetable oils can be used as the oiliness agent.

  As the metal deactivator, a metal deactivator such as benzotriazole can be used.

  The above-mentioned additives that can be used in the grease composition of the present invention 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.

  The grease composition of the present invention is not particularly limited in its application and can be applied to various devices, but is preferably applied to a rolling device. Examples of rolling devices to which the grease composition of the present invention can be applied include rolling bearings, ball screws, linear guide devices, linear motion bearings, and the like.

  Specifically, for example, when the rolling device is a rolling bearing, the grease composition of the present invention is enclosed in a space in the inner ring and the outer ring, and in addition, when the rolling device is a ball screw, the screw shaft and In the case of a nut, also in the case of a linear guide device, the guide rail and the slider are sealed.

(Rolling device)
Next, the rolling device of the present invention will be described in detail.

  The rolling device of the present invention is characterized in that the above-described grease composition is enclosed. Since the rolling device of the present invention has such a configuration, it has improved high-temperature durability and peelability.

  Embodiments of a rolling device according to the present invention will be described with reference to the drawings.

  FIG. 1 is a longitudinal sectional view showing the structure of a double-row angular ball bearing 10 which is an embodiment of a rolling device according to the present invention.

  The double-row angular contact ball bearing 10 of the present embodiment includes a double-row outer ring raceway 17, 17 provided on the inner peripheral surface of the outer ring 15 and an inner ring raceway 18, 18 provided on each outer peripheral surface of the inner ring 16, 16. A plurality of rolling elements (balls) 19, 19 are provided on the outer ring 15 and the inner rings 16, 16 so as to freely rotate. Further, the space between the outer ring 15 and the inner rings 16, 16 is sealed with a sealing device 1.

  The sealing device 1 is formed by integrally molding a metal slinger 2 and a sealing material 3 made of an elastic material. The slinger 2 includes an outer diameter side cylindrical portion 5 that can be fitted and fixed to the inner peripheral surface of the end portion of the outer ring 15, and an inner ring portion 6 that is bent radially inward from the axial inner end edge of the outer diameter side cylindrical portion 5. A first member having an approximately L-shaped cross section and having an annular shape as a whole, an inner diameter side cylindrical portion 8 that can be fitted and fixed to the outer peripheral surface of the outer end of the inner ring 16, and an axis of the inner diameter side cylindrical portion 8 A second member having an L-shaped cross section and an annular shape as a whole, including an outer annular portion 9 bent outward in the diameter direction from the outer edge in the direction.

  The seal material 3 includes three seal lips 3 a, 3 b, and 3 c on the outer side, the middle side, and the inner side, and the outer edge of the outer seal lip 3 a located on the outermost side is an outer ring that forms the slinger 2. The inner edge of the inner diameter side cylindrical portion 8 constituting the slinger 2 is slidably contacted with the inner surface of the portion 9 over the entire circumference, and the remaining two seal lips, ie, the intermediate seal lip 3b and the inner edge of the inner seal lip 3c Exhibits high sealing performance by sliding over the surface.

  The grease composition is enclosed in a space formed by the outer ring 15, the inner rings 16, 16, the balls 19 and the sealing device 1. Although there is no restriction | limiting in the sealing amount of a grease composition, It is preferable to occupy 25-45 volume% of the said space.

  The present invention can be applied not only to rolling bearings but also to various other types of rolling devices. For example, a ball screw, a linear guide device, a linear motion bearing, or the like.

  The rolling device of the present invention provided with the above-described grease composition has excellent lubricity and a long life even at high temperatures. Therefore, automotive electrical components such as alternators and electromagnetic clutches, and automotive engine supplements such as idler pulleys. Like a machine, it can be suitably used for rotating parts and sliding parts of equipment used under high temperature and high speed conditions.

  Hereinafter, the present invention will be described more specifically with reference to examples and test examples of the present invention. However, the present invention is not limited to the examples.

  The structures of the grease compositions of Examples 1 to 29 and Comparative Examples 1 to 3 are as shown in Tables 1 to 5. Each grease composition includes, as additives, 1.0% by weight of an amine-based antioxidant, 1.0% by weight of zinc naphthenate-based rust inhibitor, and 0.5% by weight of the entire grease composition. It contains a sorbitan monooleate rust inhibitor and 0.05% by weight of a benzotriazole metal deactivator.

  For each of the grease compositions of Examples 1 to 29 and Comparative Examples 1 to 3, the following seizure test, low temperature abnormal noise test, rust prevention test, rapid acceleration / deceleration test, and high temperature consistency measurement were performed.

[About seizure test]
A test bearing was prepared by enclosing 1 g of each grease composition in a double-row angular contact ball bearing (see FIG. 1) with a contact rubber seal having an inner diameter of 35 mm, an outer diameter of 52 mm, and a width of 20 mm. And it was made to rotate at the rotational speed of outer ring rotation 10000min- ^{1 on} condition of bearing temperature 180 degreeC and radial load 1960N, and time until seizure occurred and the temperature of an outer ring rose to 190 degreeC or more was made into the lifetime. The results are shown as relative values with the seizure life of Comparative Example 1 as 1.0.

  FIG. 2 shows the change in seizure life when the addition amount of the montanic acid partly saponified ester wax as the additive wax is changed in the composition of Example 1. The lifetime was evaluated by relative values in the same manner as above.

[Low temperature abnormal noise test]
A test bearing was prepared by enclosing 3.5 g of each grease composition in a single row deep groove ball bearing with a contact rubber seal having an inner diameter of φ25 mm, an outer diameter of φ62 mm, and a width of 17 mm. Then, after rotating the inner ring under conditions of −30 ° C. and an axial load of 980 N, an operation of rotating for 5 seconds at 3600 min ⁻¹ was repeated 5 times to confirm whether or not abnormal noise was generated. The case where abnormal noise was generated was regarded as rejected.

[Rust prevention test]
2.7 g of each grease composition was sealed in a single row deep groove ball bearing having an inner diameter of 17 mm, an outer diameter of 47 mm, and a width of 14 mm, and after running-in (rotating) for 30 seconds at a rotation speed of 1800 min ⁻¹ , 0.5 ml of salt water of wt% was injected and run ^- in again for 30 seconds at a rotational speed of 1800 min ⁻¹ . Next, the ball bearing was left for 48 hours in a constant temperature and humidity chamber adjusted to 80 ° C. and 100% RH, and then the ball bearing was disassembled and the rust generated on the raceway surface was observed with the naked eye. And it evaluated to the following ranks.
# 7: No generation of rust # 6: Slightly rusted rust # 5: Spot-like rust with a diameter of 0.3 mm or less # 4: Rust with a diameter of 1.0 mm or less # 3: 5.0 mm or less in diameter Rust # 2: Rust with a diameter of 10.0 mm or less # 1: Rust occurs on almost the entire raceway surface Note that # 7 to # 5 have good rust prevention properties, and # 4 to # 1 have poor rust prevention properties It was.

[Rapid acceleration / deceleration test]
The peeling life was evaluated by rapidly accelerating and decelerating a bearing incorporated in an alternator using an engine. That is, 2.36 g of each grease composition is enclosed in a single row deep groove ball bearing (inner diameter φ17 mm, outer diameter φ47 mm, width 14 mm) and incorporated in an alternator, and engine speed 1000 to 6000 min ⁻¹ (bearing speed 2400 to 14400 min ^{− 1} ) Repeatedly, the bearing was continuously rotated under the condition of a pulley load of 1560 N in a room temperature atmosphere, and the test was conducted with a target of 500 hours. The test was terminated when the bearing outer ring raceway was separated and vibrations occurred. A result is shown by the time until peeling occurs.

[High temperature consistency measurement]
In order to confirm that the grease did not harden at a high temperature, each grease composition was put in a consistency measuring cup, heated at 160 ° C. for 24 hours, and then taken out to measure the consistency.

  The results of the above tests are shown in Tables 1 to 5 together with the compositions.

The symbols in the compositions shown in Tables 1 to 5 are as follows.
1) The numbers in the “Thickener” column indicate the ratio of each urea to the total urea, the numbers in the “Base oil type” column indicate the ratio of each base oil to the total base oil, The numbers in the columns of “Amount of Agent”, “Amount of Base Oil”, and “Wax Type (Including Metal Soap)” indicate the ratio to the entire grease composition. In the examples where the amount of base oil is not shown in the table, the amount of base oil is the amount obtained by excluding other components other than the base oil from the total amount of the grease composition.
2) Diurea formed by the reaction of 4'4-diphenylmethane diisocyanate and p-toluidine 3) Diurea formed by the reaction of 4'4-diphenylmethane diisocyanate and cyclohexylamine 4) of 4'4-diphenylmethane diisocyanate and stearylamine Diurea produced by reaction 5) Aromatic ester oil: Kinematic viscosity at 40 ° C. 50 mm ² / s
6) Dialkyl diphenyl ether oil: Kinematic viscosity at 40 ° C. 100 mm ² / s
7) Pentaerythritol ester oil: Kinematic viscosity at 40 ° C. 70 mm ² / s
8) Poly α-olefin oil: kinematic viscosity at 40 ° C. 47 mm ² / s
9) Montanic acid wax (Drip point: 85 ° C)
10) Montanic acid partially saponified ester wax (Drip point: 103 ° C)
11) Calcium montanate (drop point: 147 ° C)
12) Montanic acid sodium salt (Drip point: 170 ° C)
13) Polyethylene wax (Drip point: 120 ° C)
14) Polypropylene wax (Drip point: 150 ° C)
From the above test results, the following is clear.

  The grease compositions of Examples 1 to 15, 21, 22, 25, 26, and 29 showed good baking life, whereas Comparative Examples 2 and 3 did not contain an aromatic ester (AE). The seizure resistance at high temperatures was poor.

  The grease compositions of Examples 1 to 29 showed good rust prevention properties. Therefore, the grease compositions of Examples 1 to 29 can also be suitably used for bearings that are used in harsh environments that easily come into contact with rainwater or the like and easily generate rust.

  Further, the grease compositions of Examples 1 to 29 which are nonpolar wax, polar wax or metal soap additive according to the present invention have almost no change in consistency, while Comparative Example 1 which is an additive-free product thereof. The grease composition of ˜3 has a reduced consistency and is harder. From this, it can be said that grease hardening can be suppressed at high temperature by adding nonpolar wax, polar wax or metal soap.

  The present invention has a low degree of curing even at high temperatures, has excellent grease fluidity especially under high temperature and high speed conditions, has a long life even under high temperatures, and is useful for rolling devices, etc. As a rolling device with improved durability and peeling resistance, it has industrial applicability.

FIG. 1 is a longitudinal sectional view showing a structure of a double row angular contact ball bearing which is an embodiment of a rolling device in which the grease composition of the present invention is enclosed. FIG. 2 is a graph showing the relationship of the seizure life ratio with respect to the added amount of wax contained in the grease composition of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Double row angular contact ball bearing, 15 ... Outer ring, 16 ... Inner ring, 17 ... Outer ring raceway, 18 ... Inner ring raceway, 19 ... Rolling element (ball), 1 ... Seal device, 2 ... Slinger, 3 ... Seal material, 3a ... Outer seal lip, 3b ... Intermediate seal lip, 3c ... Inner seal lip, 5 ... Outer diameter side cylindrical part, 6 ... Inner ring part, 8 ... Inner diameter side cylindrical part, 9 ... Outer ring part

Claims (5)

  A grease composition comprising a urea compound as a base oil and a thickener, wherein the non-polar wax, polar wax or metal soap is contained in an amount of 0.5 to 20% by mass in the total amount of the grease composition. Stuff.   The grease composition according to claim 1, wherein the nonpolar wax is a polyolefin wax.   The grease composition according to claim 1 or 2, wherein the polar wax is a montan wax.   The grease composition according to claim 1, wherein the urea compound is diurea.   A rolling device comprising the grease composition according to any one of claims 1 to 4.

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