JPH05140576A - Grease composition for bearing encapsulation - Google Patents

Abstract

PURPOSE:To obtain the subject grease composition capable of suppressing the abnormally high temperature development in bearing startup at low temperatures while retaining its high-temperature durability by incorporating a specific alicyclic diurea compound as consistency enhancer in a base oil comprising a poly-alpha- olefin oil and alkyldiphenyl ether oil. CONSTITUTION:The objective grease composition is obtained by incorporating (A) a base oil comprising a poly-alpha-olefin oil and an alkyldiphenyl ether oil at the weight ratio of (0.5 to 0.9):(0.1 to 0.5) with (B) as consistency enhancer, 5-40wt.% of an alicyclic diurea compound produced by reaction of a diisocyanate of the formula (R1 is 7-13C aromatic hydrocarbon; R2 and R3 are each cyclohexyl or 8-20C alkyl) (e.g. 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate with a monoamine such as cyclohexylamine, stearylamine, cetylamine or laurylamine. A rustproof agent is pref. added to this composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grease composition for lubricating electric components such as idler pulleys and tension pulleys for automobiles or bearings for auxiliary machinery.

[0002]

2. Description of the Related Art Generally, many electric components for automobiles and accessories are used in a high temperature engine room.
Further, along with the demand for higher performance of parts, longer life under high temperature use conditions has been required.

The bearings used in the above-mentioned electric components for automobiles and auxiliary machinery are sealed bearings filled with grease, and the life of such bearings is determined by the durability of the grease. Therefore, the grease that has been conventionally used for such electrical components and bearings for auxiliary equipment is selected to have good high temperature durability, and its composition is, for example, mineral oil as a base oil, synthetic hydrocarbon, polyol ester oil, Polyphenyl ether oil, silicone oil, and fluorine oil were used, and lithium soap, lithium complex, polyurea, and fluorine resin were used as thickeners.

[0004]

However, if the grease having high temperature durability is sealed in the sealed bearing, abnormal noise (hereinafter referred to as cold noise) is generated at the time of starting at low temperature in cold regions, There is a problem that it is not possible to maintain quietness.

Further, since water such as muddy water easily enters the inside of the bearing for automobiles, it is necessary to consider the rust preventive property inside the bearing.

Therefore, according to the present invention, while maintaining high temperature durability (long life), generation of abnormal noise during cold is suppressed and the quietness of the sealed bearing is maintained over a wide temperature range from high temperature to low temperature. The challenge is to use grease that also considers the rust prevention of bearings.

[0007]

In order to solve the above-mentioned problems, the present invention provides a poly-α-olefin oil and an alkyldiphenyl ether oil in a weight ratio of 0.5-0.9: 0.1-0.5. An alicyclic diurea compound represented by the following formula as a thickener was added to the blended base oil in an amount of 5 to 40% by weight.

[0008]

[Chemical 2]

Further, a rust preventive agent may be added to the bearing-filling grease. The details will be described below.

The poly-α-olefin oil used in this invention is
It has a structure in which an α-olefin is low-polymerized and hydrogen is added to the terminal double bond, and examples thereof include those represented by the following formula.

[0011]

[Chemical 3]

The alkyl diphenyl ether oil used in the present invention contains 1 mol of diphenyl ether and 1 carbon atom.
It is obtained by an addition reaction of 1 to 3 mol of an α-olefin of 0 to 22, but its properties differ depending on the number of carbon atoms of the α-olefin and the number of mols used. The blending weight ratio of the poly alpha olefin oil and the alkyl diphenyl ether oil in the base oil of this invention is 0.5 to 0.9: 0.1 to 0.5.
Is. This is because if the amount of poly-α-olefin oil in the base oil is less than the above range, the performance at low temperature is poor, and if it exceeds the above range, heat resistance cannot be sufficiently obtained, which is not preferable.

Next, the alicyclic diurea compound represented by the above formula (2) used as a thickener in the present invention is obtained by the reaction of diisocyanate and monoamine. Examples of the diisocyanate forming R ₁ include 4,4′-diphenylmethane diisocyanate and tolylene diisocyanate. In the formula of Chemical formula ₂ , cyclohexylamine, stearylamine, cetylamine, laurylamine and the like can be mentioned as monoamines forming R ₂ and R ₃ .
The amount of such an alicyclic diurea compound added to the base oil is 5 to 40% by weight. Because the grease obtained by adding a small amount of diurea compound of less than 5% by weight is
This is because it becomes a liquid with a low viscosity, and becomes solid when it exceeds 40% by weight, which makes it unsuitable for the properties of the grease for bearing encapsulation.

Next, as the rust preventive agent used in the present invention, barium sulfonate is preferred. The amount added is preferably about 0.1 to 5% by weight because it is efficient.

[0015]

The grease composition for bearing encapsulation of the present invention is excellent in both low temperature property and heat resistance because the base oil is a mixed oil in which alkyl diphenyl ether oil and poly α-olefin oil are blended in a predetermined ratio. Becomes Further, as a thickener to be added to such a base oil, an alicyclic diurea compound, which is superior in thermal stability, oxidative stability and adhesiveness to metal soaps such as lithium soap and sodium soap, is used. Therefore, it has heat resistance and high life at high temperature. Also. The barium sulfonate is added to the above composition to provide remarkable rust prevention.

[0016]

【Example】

[Examples 1 and 2] A base oil composed of a mixed oil of a poly-α-olefin oil and an alkyl diphenyl ether oil was prepared at a blending ratio shown in Table 1, and 1 mol of 4,4'-diphenylmethane diisocyanate was prepared as shown in Table 1. 2% monoamine (cyclohexylamine) is dissolved in the remaining half amount of the base oil, and the mixture is added with stirring, and then the mixture is reacted at 100 to 120 ° C. for 30 minutes with stirring to react the oil. A cyclic diurea compound was incorporated into the base oil. Phenothiazine (0.5% by weight) as an antioxidant was added thereto, and the mixture was further stirred at 100 to 120 ° C for 10 minutes. After cooling, 3% by weight of rust preventive barium sulfonate was added and mixed, and homogenized with a three-roll mill to obtain a grease. The grease was tested for consistency, dropping point and high temperature durability, and the results are also shown in Table 1.

Consistency: Measured according to JIS K2220 5.3.

Drop point: The temperature at which the grease melts and begins to fall by its own weight (° C) is the grease drop point test method JIS
It was measured according to K2220 5.4.

High temperature durability test: Bearing 6204 was filled with grease, iron non-contact type seals were provided on both sides, and this was installed in a bearing operating device, the ambient temperature was kept at 180 ° C., radial load 67 N, axial load. Under the condition of 67 N, the inner ring was rotated at a speed of 10,000 rpm and the grease in the bearing was deteriorated, so that the rotation torque of the bearing became excessive, and the input current of the electric motor driving the rotation of the main shaft changed the limiting current to the limiting current. The life time was defined as the time until the motor stopped after exceeding the limit.

Abnormal measurement during cold: Grease is sealed in the bearing 6203, rubber contact seals are provided on both sides, the bearing is set in the housing, and it is put in a low temperature tank at -40 ° C. to cool sufficiently. After that, attach it to a bearing device installed at room temperature, and rotate the inner ring at a speed of 2000 revolutions per minute under the condition of an axial load of 1.96N, and check for the occurrence of abnormal sound (audible noise during cold) due to hearing. It was

Rust test: According to the rust test method of ASTM D 1743, the bearing 6302 was filled with 1.6 to 1.9 g of sample grease and then sealed with a rubber, and the axial load was set to 39.2 N. Plus 1800 per minute
It was run-in for 1 minute by rotation. Next, add 3% saline to 0.
After injecting into the 5ml bearing, apply an axial load of 3 again.
9.2 N was added and the rotation was performed at 1800 rpm for 3 minutes. After placing this bearing in a desiccator and leaving it at 40 ° C. for 100 hours, the rusting condition was examined. Regarding the rusting condition, the inner ring race was divided into 22 equal parts in the circumferential direction and the outer ring race was divided into 30 equal parts in the circumferential direction, and the rusted sections were counted. The average of n = 4 times was taken as the rust score.

[0022]

[Table 1]

[Comparative Examples 1 to 3] A grease containing a base oil as a sole component of a poly-α-olefin oil and an alicyclic diurea compound as a thickener was used as Comparative Example 1, and a base oil as a sole component of an alkyl diphenyl ether oil. A grease using a urea compound other than an alicyclic group was used as Comparative Example 2, and a mixture of an alkyl diphenyl ether oil (80%) and a poly-α-olefin (20%) in a proportion exceeding the above-mentioned predetermined mixing ratio was used as a base oil and thickened. Comparative Example 3 in which a grease using a urea compound other than an alicyclic group is used as an agent
As a result, the same test as in Example 1 was performed, and the results are shown in Table 1.

As is clear from the test results in Table 1, Comparative Examples 1 to 3 in which the poly-α-olefin oil and the alkyl diphenyl ether oil were not blended within the predetermined range, and the urea compound other than the alicyclic group was used as the thickener. Comparative Examples 2 and 3, which employ No. 3, are inferior in either high temperature durability or abnormal noise during cold. On the other hand, in Examples 1 and 2 in which the base oil composition was set to the predetermined mixing ratio and the alicyclic diurea compound was used as the thickener, the high temperature durability was excellent, no abnormal noise was generated during cold, and the barium sulfonate was used. The rust prevention effect was remarkable.

[0025]

[Effect] Since the grease composition for enclosing a bearing according to the present invention is configured as described above, while maintaining sufficient high temperature durability, generation of abnormal noise during cold is suppressed, and a wide temperature range from high temperature to low temperature is achieved. Therefore, the quietness of the sealed bearing can be maintained.
Moreover, since the rust preventive property is remarkably exhibited, it can be said that it can greatly contribute to the extension of the life of the bearing itself and the industrial utility value is extremely high.

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Claims (2)

[Claims] 1. A base oil prepared by blending a poly-α-olefin oil and an alkyldiphenyl ether oil in a weight ratio of 0.5 to 0.9: 0.1 to 0.5, and a fat represented by the following formula as a thickener. A grease composition for bearing encapsulation, which comprises 5 to 40% by weight of a cyclic diurea compound. [Chemical 1] 2. A grease composition for bearing encapsulation, which is obtained by adding a rust preventive agent to the grease for bearing encapsulation according to claim 1.