JP2003201495A - Grease composition and rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grease composition imparting an excellent seize resistance under high temperatures close to 200°C, and to provide a rolling bearing sealing the grease. <P>SOLUTION: The grease composition exhibits a worked penetration of 185-355 after keeping at 180°C and preferably contains a specific diurea compound as a thickener, and the ball bearing sealed with the grease composition. <P>COPYRIGHT: (C)2003,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 and a grease composition enclosed in the rolling bearing, and particularly to high temperature components such as electric components of automobiles, alternators and intermediate pulleys for engine accessories, and electromagnetic clutches for car air conditioners. The present invention relates to a rolling bearing which can be suitably used under high-speed and high-load conditions and has an excellent high-temperature seizure life, and a grease composition enclosed in the rolling bearing.

[0002]

Rolling bearings are generally used for electric components of automobiles, alternators and intermediate pulleys as engine accessories, electromagnetic clutches for car air conditioners, etc., and grease is mainly used for lubrication thereof.

On the other hand, automobiles are forced to reduce the engine room space due to the spread of FF vehicles for the purpose of downsizing and weight reduction, and further due to the demand for expansion of the migration space. As the size and weight of the machine are further advanced, higher performance and higher output are required for each of the above parts. However, downsizing is inevitable due to downsizing, and for example, in electromagnetic alternators and car air-conditioning electromagnetic clutches, increasing the speed compensates for the decrease in the output. Become. Further, due to the demand for quietness improvement, the sealing of the engine room is promoted, and the temperature rise in the engine room is promoted. Therefore, it is also necessary for each of the above parts to withstand high temperature. Recently, the operating temperature tends to be particularly high. For example, in the case of an alternator, the heat generated inside the alternator is cooled by the cooling water of the radiator, so the bearing temperature may reach 160 to 200 ° C.

As a countermeasure against such high speed and high temperature, it is widely practiced to change the composition of the thickener of grease.
For example, JP-A-9-3466 discloses a grease composition in which a base oil such as a dialkyldiphenyl ether, an ester-based synthetic oil, or a poly-α-olefin is mixed with a mixture of a diurea compound having a specific molecular structure as a thickener. Further, Japanese Patent Publication No. 5-24958 discloses a grease composition containing a diurea compound obtained by reacting a mixed amine of alkylphenylamine and cyclohexylamine with a diisocyanate compound as a thickener. There is. However, rolling bearings containing a grease composition containing these diurea compounds as thickeners have good seizure resistance under high-speed conditions.
At a high temperature of 60 ° C. or higher, seizure resistance is insufficient and it is difficult to use.

Further, the conventional urea type grease has a common problem that the grease is hardened and sometimes the thickener is broken and softened. That is, the urea-based grease is characterized in that it cures when the temperature decreases after being exposed to a high temperature (thermosetting property). In addition, a urea compound having low heat resistance softens because urea starts to decompose. In an actual automobile, the bearing has a high temperature when it is in operation, and it has a normal temperature when it is stopped. Therefore, if grease with a large thermosetting property is filled in, the fluidity may be insufficient due to hardening of the grease when restarting, and seizure may occur. . Further, when the grease softens, grease leakage easily occurs, so that the grease in the bearing becomes insufficient and seizure occurs. As described above, the change in consistency of grease with time has a significant influence on the seizure performance of the bearing.

[0006]

As described above, in the conventional urea type grease, the consistency change with time is large under the use environment of 160 to 200 ° C., and seizure resistance is not sufficient. It cannot meet high-speed and high-temperature.

Therefore, the present invention has been made in consideration of the above circumstances.
An object of the present invention is to provide a grease composition capable of imparting excellent seizure resistance even at a high temperature close to 0 ° C, and a rolling bearing in which the grease is enclosed.

[0008]

In order to solve the above problems, the present invention provides a grease composition characterized by having a work penetration of 185 to 355 when left at 180 ° C., and A rolling bearing containing the grease composition is provided. In particular, it is preferable to use a specific diurea compound described later as a thickener.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

In the present invention, the structure of the rolling bearing itself is not limited, and for example, a ball bearing shown in a sectional view in FIG. 1 can be exemplified. The illustrated ball bearing 1 has an inner ring 10
A plurality of balls 13 are rotatably held via a cage 12 between the outer ring 11 and the outer ring 11, and a bearing space S is filled with a grease composition described later and sealed by a seal 14. ing.

[Mixture Penetration] The grease composition is 18
Mixing consistency is 180-355 when left at 0 ℃
Must be If the mixing consistency is less than 180, the grease composition is too hard to obtain sufficient fluidity. On the other hand, when it exceeds 355, the grease composition is remarkably softened to cause grease leakage.

[Base Oil] The base oil to be used is not particularly limited, and any oil usually used as a base oil for lubricating oil can be used. Preferably, in order to avoid noise generation at low temperature startup due to insufficient low temperature fluidity and seizure due to insufficient oil film formed at high temperature, the kinematic viscosity at 40 ° C. is preferably 10 to 400 mm ² / sec, more preferably Is 20 to 250 mm ² / sec, more preferably 40 to 150 m
A base oil of m ² / sec is desirable.

Specific examples include mineral oil-based, synthetic oil-based or natural oil-based lubricating oils. As the mineral oil-based lubricating oil, it is preferable to use one obtained by appropriately combining mineral oil under reduced pressure distillation, oil agent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, sulfuric acid washing, clay refining, hydrorefining, etc. it can. The synthetic oil-based lubricating base oil, hydrocarbon-based oil,
Aromatic oils, ester oils, ether oils and the like can be mentioned. As the hydrocarbon-based oil, normal paraffin,
Isoparaffin, polybutene, polyisobutylene, 1-
Examples thereof include decene oligomers, poly-α-olefins such as 1-decene and ethylene cooligomers, and hydrides thereof. Examples of the aromatic oil include alkylbenzene such as monoalkylbenzene and dialkylbenzene, and alkylnaphthalene such as monoalkylnaphthalene, dialkylnaphthalene and polyalkylnaphthalene. Examples of the ester oil include dibutyl sebacate, di-2-ethylhexyl sebacate, dioctyl adipate, diisodecyl adipate,
Ditridecyl adipate, ditridecyl glutarate,
Diester oils such as methyl acetylsinolate, aromatic ester oils such as trioctyl trimellitate, tridecyl trimellitate, tetraoctyl pyromellitate, trimethylol propane caprylate, trimethylol propane pelargonate, penta Examples include polyol ester oils such as erythritol-2-ethylhexanoate and pentaerythritol belargonate, and complex ester oils that are oligoesters of polyhydric alcohols and mixed fatty acids of dibasic acid / monobasic acid. . Examples of the ether-based oil include polyethylene glycol, polypropylene glycol, polyethylene glycol monoether, polyglycol such as polypropylene glycol monoether, monoalkyl triphenyl ether, alkyl diphenyl ether, dialkyl diphenyl ether, pentaphenyl ether, tetraphenyl ether, monoalkyl. Examples thereof include phenyl ether oils such as tetraphenyl ether and dialkyl tetraphenyl ether. Other synthetic lubricating base oils include tricresyl phosphate, silicone oils, perfluoroalkyl ethers and the like. The natural oil-based lubricating base oil, beef tallow, lard, soybean oil, rapeseed oil, rice bran oil, coconut oil,
Examples include fats and oils such as palm oil and palm kernel oil, and hydrides thereof. These base oils can be used alone or as a mixture, and are adjusted to the preferable kinematic viscosity described above.

[Thickener] If the workability of the grease composition when left at 180 ° C. is 185 to 355, there is no particular limitation, but it is represented by the following general formulas (1) to (3). It is preferable to use a mixture of diurea compounds.

[0015]

[Chemical 3]

In the formula, R ₁ represents an aromatic ring-containing hydrocarbon group having 7 to 12 carbon atoms, R ₂ represents a divalent aromatic ring-containing hydrocarbon group having 6 to 15 carbon atoms, and R ₃ represents A cyclohexyl group or an alkylcyclohexyl group having 7 to 12 carbon atoms is shown. Specific examples of R ₁ include a toluyl group, a xylyl group, a β-phensyl group, a t-butylphenyl group, a dodecylphenyl group, a benzyl group and a methylbenzyl group. Further, examples of R ₂ include the groups exemplified below.

[0017]

[Chemical 4]

Examples of R ₃ include cyclohexyl group, methylcyclohexyl group, dimethylcyclohexyl group, ethylcyclohexyl group, diethylcyclohexyl group, propylcyclohexyl group, isopropylcyclohexyl group, 1-methyl-3-propylcyclohexyl group, butylcyclohexyl group. , A pentylcyclohexyl group, a pentylmethylcyclohexyl group, a hexylcyclohexyl group, and the like, and a cyclohexyl group or an alkylcyclohexyl group having 7 to 8 carbon atoms, such as a methylcyclohexyl group and an ethylcyclohexyl group, are particularly preferable.

[0019] In a mixture of diurea compounds described above, the value of [R ₁ moles / (number of moles + R ₈ of R _1)], it is 0 to 0.50. If this value exceeds 0.50, the fluidity becomes low and the bearing may seize.

Further, as a thickener, the following general formula (4)
A diurea compound represented by the following general formula (5) and a diurea compound represented by the general formula (4): a diurea compound represented by the general formula (5) = 0.1 ~
You may mix | blend in the ratio of 0.9: 0.9-0.1.

[0021]

[Chemical 5]

In the formula, R ₄ and R ₅ are aromatic ring-containing hydrocarbon groups having 7 to 12 carbon atoms, cyclohexyl groups or alkylcyclohexyl groups having 7 to 12 carbon atoms, and 8 to 2 carbon atoms.
The straight-chain alkyl group of 0 is shown, and they may be the same or different. Specific examples of the aromatic ring-containing hydrocarbon group having 7 to 12 carbon atoms, cyclohexyl group or alkylcyclohexyl group having 7 to 12 carbon atoms are the same as R ₁ and R _{3 in} the general formulas (1) to (3). Is.

The content of these diurea compounds is as follows:
NLGI No. 1-No.
3 to 10 to 35 mass of the total amount of the grease composition
It is desirable to set it to%.

[Additives] The grease composition may contain known additives, if necessary, in order to enhance the excellent performance. Examples of the additive include gelling agents such as metallic soap, benton, and silica gel; amine-based, phenol-based, sulfur-based, zinc dithiophosphate, and other antioxidants; chlorine-based, sulfur-based, phosphorus-based, zinc dithiophosphate, Extreme pressure agents such as organic molybdenum; Oily agents such as fatty acids and animal and vegetable oils; Rust inhibitors such as petroleum sulfonate, dinonylnaphthalene sulfonate, sorbitan ester; Metal deactivators such as benzotriazole and sodium nitrite; Polymethacrylate, Examples thereof include viscosity index improvers such as polyisobutylene and polystyrene, and these may be added alone or in combination of two or more. At this time, the addition amount of additives and the like is not particularly limited as long as the desired object of the present invention can be achieved, but usually 20% by mass or less can be contained in the grease composition.

[Production Method] There are no particular restrictions on the method of preparing the grease composition. However, it is generally obtained by reacting a thickener in a base oil. The manufacturing conditions such as heating temperature and stirring / mixing time are appropriately set depending on the base oil, thickener, additive, etc. used.

After the additives are added, it is necessary to stir them sufficiently to uniformly disperse them. When performing this treatment, heating is also effective.

[0027]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

(Preparation of Test Grease A) Half of synthetic hydrocarbon oil (PAO) was placed in the first container, and cyclohexylamine (cyclohexyl group: R ₁ ) and p-toluidine (p-toluyl group: R ₃ ) were put therein. ), The number of moles of R ₁ /
The value of (the number of moles of R ₁ + the number of moles of R ₃ ) is changed so as to be 0 to 1.0, and the mixture is heated to 70 to 80 ° C. Half of the synthetic hydrocarbon oil (PAO) and diphenylmethane diisocyanate were placed in the second container, heated to 70 to 80 ° C., added to the first container and stirred. Although the temperature of the reaction product rises due to the heat of reaction, stirring is continued in this state for about 30 minutes to sufficiently carry out the reaction, and then the temperature is raised to 170-
It was kept at 180 ° C. for 30 minutes and cooled. Then, add an antioxidant and pass through a roll mill to test grease A.
Got Each test grease A was adjusted so that the initial workability was NLGI No.2.

(Preparation of Test Grease B) Half of the amount of dialkyl phenyl ether oil and p-toluidine are put in the first container and heated to 70-80 ° C. A second container was charged with half of the basic dialkyldiphenyl ether oil and tolylene diisocyanate and heated to 70 to 80 ° C.
It was added to the container and stirred. Although the temperature of the reaction product rises due to the heat of reaction, stirring was continued in this state for about 30 minutes to carry out the reaction sufficiently, then the temperature was raised, and the temperature was maintained at 170 to 180 ° C. for 30 minutes and cooled. Then, an antioxidant was added and the mixture was passed through a roll mill to obtain a grease containing the diurea compound represented by the general formula (4).

In a first container, a half amount of dialkyl phenyl ether oil and p-toluidine were put, and 70 to 80
Warm to ℃. Half the amount of dialkyldiphenyl ether oil and diphenylmethane diisocyanate were put in the second container, heated to 70 to 80 ° C., added to the first container and stirred. Although the temperature of the reaction product rises due to the heat of reaction. Stirring is continued in this state for about 30 minutes, and after the reaction is sufficiently performed, the temperature is raised and the temperature is maintained at 170 to 180 ° C for 30 minutes
Cooled. Then, an antioxidant was added and the mixture was passed through a roll mill to obtain a grease containing the diurea compound represented by the general formula (5).

Then, the grease and the grease were mixed by changing the ratio such that the grease: grease = 0 to 1.0: 1.0 to 0, and the mixture was passed through a roll mill to obtain a test grease B. Each test grease B was adjusted so that the initial workability was NLGI No.2.

[0032]

[Table 1]

[0033] Using the above test greases A, performs grease consistency check test and seizure life test shown below, the worked penetration for R ₁ in moles / (R ₁ molar number + number of moles of R ₃₎ And the relationship between seizure resistance was investigated. The results are shown in Figure 2. Also, using the test grease B, the general formula
The relationship between the mixing consistency and the seizure resistance with respect to the ratio of the diurea compound represented by (4) to the diurea compound represented by the general formula (5) was investigated. The results are shown in Fig. 3.

(Grease consistency confirmation test) φ30 mm
Put each test grease in a petri dish of 240 and 240 at 180 ℃
The mixing consistency after standing for a time was measured.

(Seizure Life Test) Inner Diameter φ17 mm, Outer Diameter φ
2.3g of each test grease was filled in a deep groove ball bearing with a contact rubber seal of 52mm and a width of 16mm (see Fig. 1), and the bearing was continuously rotated under the conditions of inner ring rotation speed 20000min ^-1 , bearing temperature 170 ° C and radial load 98N. It was The test was terminated when seizure occurred and the temperature of the bearing outer ring rose to 180 ° C. or higher. The test was conducted in four cases each. Average time 1000
Passed more than time.

As shown in FIG. 2, the number of moles of R ₁ /
Grease having a value of (the number of moles of R ₁ + the number of moles of R ₈ ) in the range of 0 to 0.50 has the mixing consistency in the range of 185 to 355, and the rolling bearing in which this grease is encapsulated has seizure resistance. It can be seen that it has excellent properties. Further, as shown in FIG. 3, the diurea compound represented by the general formula (4) and the general formula '
The grease containing the diurea compound represented by (5) at a ratio of the diurea compound represented by the general formula (4) in the range of 0.1 to 0.9 has a workability of 185 to 355.
It can also be seen that the rolling bearing containing this grease is also excellent in seizure resistance.

[0037]

Industrial Applicability As described above, the grease of the present invention has a mixing consistency of 185 to 355 when left to stand at 180 ° C., and preferably the grease of the present invention containing a specific diurea compound as a thickener is conventionally used. The seizure resistance is significantly improved compared to the grease of No. 1, and rolling encapsulating this grease also has excellent seizure resistance.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a rolling bearing of the present invention.

FIG. 2 is a graph showing the relationship between the number of moles of R ₁ / (the number of moles of R ₁ + the number of moles of R ₃ ) in the grease, and the miscibility and seizure resistance obtained in the examples.

FIG. 3 is a general formula for grease obtained in the example.
3 is a graph showing the relationship between the proportion of each diurea compound represented by (4) and the general formula (5), and the miscibility and seizure resistance.

[Explanation of symbols]

1 ball bearing 10 inner ring 11 outer ring 12 cage 13 balls 14 seal

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C10N 40:02 C10N 40:02 50:10 50:10

Claims (4)

[Claims] 1. A grease composition having a work penetration of 185 to 355 when left at 180 ° C. 2. As a thickener, the following general formulas (1) to (3)
The grease composition according to claim 1, containing a mixture of the diurea compounds represented by: [Chemical 1] (In the formula, R ₁ represents an aromatic ring-containing hydrocarbon group having 7 to 12 carbon atoms, R ₂ represents a divalent aromatic ring-containing hydrocarbon group having 6 to 15 carbon atoms, and R ₃ represents a cyclohexyl group or a carbon group. Number 7 ~
Indicates 12 alkyl cyclohexyl group, and the value of [R ₁ moles / (number of moles + R ₈ of R _1)] in the mixture is 0 to 0.50. ) 3. As a thickener, a diurea compound represented by the following general formula (4) and a diurea compound represented by the following general formula (5) are added. : Diurea compound represented by the general formula (5) = 0.1
The grease composition according to claim 1, wherein the grease composition is contained in a ratio of 0.9: 0.9 to 0.1. [Chemical 2] (In the formula, R ₄ and R ₅ represent an aromatic ring-containing hydrocarbon group having 7 to 12 carbon atoms, a cyclohexyl group or an alkylcyclohexyl group having 7 to 12 carbon atoms, and a linear alkyl group having 8 to 20 carbon atoms. , May be the same or different groups.) 4. A plurality of rolling elements are rotatably held by a cage between an inner ring and an outer ring, and the grease composition according to any one of claims 1 to 3 is enclosed. Characteristic rolling bearing.