JPH04253796A - High-temperature-durable grease composition - Google Patents

Abstract

PURPOSE:To obtain a grease compsn. having durability and long life under a high-temp. and high-speed condition as a filling grease for a bearing used for electric parts of automobiles and auxiliary machinery. CONSTITUTION:An alkyl tetraphenyl ether oil such as a monoalkyl tetraphenyl ether or a dialkyl tetraphenyl ether or a pentaphenyl ether oil is compounded with 2-40wt.% diurea compd. prepd. by reacting a diisocyanate such as 4,4'- diphenylmethane diisocyanate and tolylene diisocyanate with a monoamine such as aniline, cyclohexylamine, stearylamine, cetylamine or laurylamine.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-temperature durable grease composition for lubricating bearings for alternators, electromagnetic clutches, idler pulleys, and other electrical components or auxiliary equipment for automobiles under high-temperature conditions.

0002

[Background Art] In recent years, electrical components for automobiles and their auxiliary equipment have been improved to become smaller and lighter, and demand for luxury products has also increased, making it necessary to improve quietness when using these components. As a result, the interior of the engine room tends to be sealed. As a result, the inside of the engine room has become even hotter, and the electrical components and auxiliary equipment used there have become increasingly required to withstand high temperatures.

The bearings used in the above-described automotive electrical components and auxiliary equipment are sealed bearings filled with grease, and the lifespan of such bearings is determined by the durability of the grease. For this reason, it became necessary to develop a grease with higher temperature and longer life, but conventionally widely used greases that use metallic soap as a thickener, i.e., a combination of thickener and base oil, are based on polyurea and mineral oil. , polyurea-ester-based, or polyurea-poly-α-olefin-based greases have a problem in that they do not extend bearing life in terms of oxidation stability, thermal stability, and volatility.

[0004] Furthermore, in order to improve the oxidation stability, thermal stability and volatility of grease, formula (2)

[0005]

[Case 2]

[0006] (In the formula, R is a straight chain alkyl group), which uses an alkyldiphenyl ether oil as a base oil and a diurea compound as a thickener (JP-A-1-2590)
No. 97) is also known, but the consistency of the grease is excessive, and sufficiently satisfactory results cannot be obtained in terms of liquefaction temperature (dropping point) and high-temperature durability in actual machine tests. Therefore, such conventional greases have not been fully satisfactory as greases for bearings that rotate at high speeds under high temperature conditions.

[0007]

[Problems to be Solved by the Invention] As stated above, in the conventional technology, there is no grease with sufficiently satisfactory oxidation stability, thermal stability, and volatility, and it is necessary to use grease for bearings used in recent electrical components and auxiliary equipment. The challenge was to create a long-life grease that would be durable under high-temperature, high-speed rotation conditions.

[0008]

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a base oil containing an alkyl tetraphenyl ether oil or a pentaphenyl ether oil as a main component, and a thickener of the formula (1).

[0009]

[Chemical formula 3]

(In the formula, R1 is an aromatic hydrocarbon group having 7 to 13 carbon atoms, R2 and R3 are a cyclohexyl group,
2 to 40% by weight of a diurea compound represented by an aromatic hydrocarbon group or an alkyl group having 8 to 20 carbon atoms, in which at least one of R2 or R3 is a cyclohexyl group or an aromatic hydrocarbon group, was blended. The details will be described below.

The alkyl tetraphenyl ether oil used in the present invention has the formula (3)

0012

[C4]

Monoalkyl tetraphenyl ether represented by (wherein R is a linear alkyl group having 12 to 18 carbon atoms) or formula (4)

[0014]

[C5]

Examples include dialkyl tetraphenyl ethers represented by the formula (wherein R is a straight-chain alkyl group having 12 to 18 carbon atoms). All of these have different structures in terms of the number of aromatic rings than the alkyldiphenyl ether oil shown by the above formula (2).

Further, pentaphenyl ether oil has the formula (
5)

[0017]

[C6]

It is shown as follows.

Next, the diurea compound represented by the formula (1) used as a thickener in the present invention is obtained by the reaction of a diisocyanate and a monoamine, and after the reaction, the diurea compound represented by R1 in the formula (1) is Examples include aromatic isocyanates such as 4,4'-diphenylmethane diisocyanate and tolylene diisocyanate. In formula (1), R2, R3
Examples of monoamines include aniline, cyclohexylamine, stearylamine, cetylamine, and laurylamine. The amount of such a diurea compound added to the base oil is 2 to 40% by weight. This is because grease obtained by adding a small amount of diurea compound, less than 2% by weight, becomes a liquid with poor viscosity;
This is because if the amount exceeds 100%, it becomes solid and the properties of the grease for sealing in a bearing are unsuitable.

[0020]

[Operation] The heat-resistant grease composition of the present invention has a base oil containing an alkyl tetraphenyl ether oil or a pentaphenyl ether oil having 4 to 5 aromatic rings as a main component, so it is different from conventional base oils. It has better oxidation stability and thermal stability than mineral oil, synthetic oil such as poly-α-olefin oil, diester oil, polyol ester oil, and alkyldiphenyl ether oil, and also has less volatilization at high temperatures. Also,
As a thickener added to such base oils, diurea compounds are used, which have better thermal stability, oxidation stability, and adhesion than metal soaps such as lithium soap and sodium soap, so they are heat resistant. , it has a long life at high temperatures.

[0021]

【Example】

Examples 1 to 3 In a solution in which 1 mol of 4,4'-diphenylmethane diisocyanate was dissolved in half of the base oil shown in Table 1,
After adding a solution of 2 mol of the monoamine shown in the remaining half of the base oil with stirring,
Stirring was continued for 0 minutes to allow reaction, resulting in a grease-like consistency. Add 0.5g of antioxidant to the grease and add 100g of antioxidant.
Stir for 10 minutes at ~120°C. Thereafter, the consistency, dropping point and high temperature durability tests of the grease homogenized with three rolls were conducted, and the results are shown in Table 1.

[0022] Consistency: JIS K2220 5.
3. Dropping point: The temperature (°C) at which the grease begins to melt and drop under its own weight, according to the Grease Dropping Point Test Method JIS K22.
20 Measured according to 5.4.

High temperature durability test: Bearing 6204 was filled with grease, iron non-contact seals were installed on both sides, this was attached to the bearing operating device, the ambient temperature was maintained at 180°C, radial load was 67N, axial load was The inner ring rotates at a speed of 10,000 revolutions per minute under the condition of 67N, and the grease inside the bearing deteriorates, causing the bearing rotational torque to become excessive, and the input current of the electric motor that drives the rotation of this main shaft to exceed the limiting current. The time until the motor stops due to excess is defined as the service life.

[0024]

[Table 1]

Comparative Examples 1 to 8 The same tests as in Examples 1 to 3 were conducted on commercially available greases with known base oils and thickeners, and the results are shown in Table 2.

[0026]

[Table 2]

As is clear from the test results in Tables 1 and 2, alkyl tetraphenyl ether oil or pentaphenyl ether oil was used as the base oil, and a diurea compound obtained by the reaction of diisocyanate and monoamine was used as the thickener. The greases used in Examples 1 to 3 had a consistency of 20.
3 to 225, and the consistency of Comparative Examples 1 to 8 (230
-280), and the dropping point is also 286-28
The grease showed a high value of 8°C and was found to be heat resistant and stable in properties at high temperatures. Further, in the high temperature durability test, Comparative Examples 1 to 8 only lasted for 16 to 405 hours, whereas the examples showed excellent durability of 423 to 714 hours.

[0028]

[Effects] As explained above, the high temperature durable grease composition of the present invention has a base oil and a thickener that have oxidative stability and
It is made of a material with excellent thermal stability, and as a grease sealed in bearings that rotate at high speed under high-temperature conditions, it exhibits extremely stable properties in terms of consistency and dropping point, and is used industrially as a grease that is durable at high temperatures. It can be said that the utility value is extremely high.

Claims (1)

[Claims] Claim 1: A base oil containing alkyl tetraphenyl ether oil or pentaphenyl ether oil as a main component, as a thickener of the formula (1) [Chemical formula 1] (wherein, R1 is an aromatic group having 7 to 13 carbon atoms) hydrocarbon group,
R2 and R3 represent a cyclohexyl group, an aromatic hydrocarbon group, or an alkyl group having 8 to 20 carbon atoms, and at least one of R2 or R3 is a cyclohexyl group or an aromatic hydrocarbon group).
A high temperature durable grease composition containing 0% by weight.