JPH0688085A - Grease composition for rotating machine bearing - Google Patents

Abstract

PURPOSE:To provide a grease composition for a rotating machine bearing very excellent in that it exhibits long life at high temperature and even in high-speed high-temperature test. CONSTITUTION:The composition is obtained by mixing 100 pts.wt. base oil composed mainly of an alkyldiphenyl ether oil with 2-34 pts.wt. thickening agent comprising a diurea compound represented by the general formula R1- NHCONH-R2-NHCONH-R3 (where R2 is a tolylene, diphenylmethane or dimethylbiphenylene group; and R1 and R3 are each 6-18C linear saturated alkyl, cycloalkyl or an aromatic hydrocarbon group, provided that the linear saturated alkyl accounts for 25-45mol% of the total of R1 and R3, the cycloalkyl 50-70mol%, and the aryl 5-25mol%).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mainly used for bearings of various rotating devices related to railway vehicles traveling at high speed, and maintains good lubrication performance, and also lubricates the bearing under high temperature and high speed conditions. The present invention relates to a lubricating grease composition which has a significantly extended life and is free from adverse effects such as poor lubrication due to high-speed rotation and has superior performance.

[0002]

2. Description of the Related Art Bearings for Shinkansen-related rotating machines, which are typical of high-speed railways, include bearings for main electric motors, bearings for blower motors, bearings for generators,
Although there are bearings for axles and the like, as the lubricants for these bearings, a grease based on a mineral oil and a lubricating oil have been mainly used as a thickener based on a lithium soap group.

[0003]

In recent years, the French high-speed railway TGV has set a new world record for high-speed running performance.
Inspired by the fact that we are updating one after another, JR companies in Japan are also studying ways to speed up the Shinkansen.
The result was that we could proceed at a fast pace.

In order to accelerate the speed of the vehicle, the first important point is how much the weight of the vehicle body can be reduced. For this reason, in a system such as oil lubrication that requires a large oil slump. Naturally, there is a limit, and there is an urgent need for a grease lubrication system that does not require such a device. Secondly, it is essential to further stabilize the vehicle body in order to promote high-speed driving, and for that purpose, consideration will be given to making the height of the vehicle body lower. .
The most wrinkle is to reduce the diameter of the wheel, and as a result, studies are underway to develop smaller bearings for axles. Now, the speed of the bearings is increasing due to the further increase in speed and the reduction in axle diameter.
No, it will result in an increase.

With the rapid development for such speeding up, the lubricant used in the bearing of the rotating machine part is the conventional lithium soap as a thickener and mineral oil. In addition to inferior heat resistance, shearing stability, high-speed lubricity, etc., the bearing-based type has many problems such as short bearing lubrication life and large bearing heat generation. Lubricant can't do enough.

In addition to these problems, in many Shinkansen vehicles, attempts are being made at many places to make the inspection cycle of the vehicle body portion longer. Due to the rapid progress of technological innovation, various equipments such as electric motors used in Shinkansen vehicles have
Shinkansen vehicles have reached the end of their service life, and it is said that the technical level has reached the point where it is completely unnecessary to replace or repair these devices while driving. However, the lubricants used in these devices have not reached this level, so the main focus of vehicle inspection during driving is the lubricating grease used to lubricate the bearings. Only the work of checking and replacing the lubricating oil is left behind.

[0007] The work of replacing the lubricant is becoming a so-called 3K work which is very disliked by workers, because it is accompanied by oil stains. for that reason,
Currently, inspections are conducted every 300,000 km, but this is 45
Studies are underway to gradually extend the inspection cycle to every 900,000, 1.35 million Km. To that end, conventional greases based on mineral oil have a short bearing lubricating life and cannot sufficiently meet such requirements.

The lubricating grease of the present invention exhibits excellent lubricating properties even under conditions of high temperature and high speed, and has a bearing lubricating life which is superior to that of the conventional one, and which has an excellent lubricating grease composition with long life. To provide.

[0009]

Means for Solving the Problems The grease for bearings of high-speed rotating machines according to the present invention has an essential condition that an alkyl diphenyl ether oil is used as a main component of a base oil portion.
The thickener contains a diurea compound represented by the following general formula in an amount of 2 to 40 parts by weight with respect to 100 parts by weight of a base oil, and relates to a grease composition. R1 -NHCONH-R2-NHCONH-R3 In the above formula, R2 represents a tolylene group, a diphenylmethane group or a dimethylbiphenylene group. R1 and R3 in the formula are straight-chain saturated alkyl groups having 6 to 18 carbon atoms,
It represents a cycloalkyl group and an aromatic hydrocarbon group. The proportions thereof are such that the linear saturated alkyl group is in the range of 25 to 45 mol%, the cycloalkyl group is in the range of 50 to 70 mol%, and the aryl group is in the range of 5 to 25 mol%.

The amines used in these reactions are n-propylamine, isopropylamine, n-butylamine, isobutylamine, s-butylamine, n-pentylamine, 3-methylbutylamine, n-heptylamine, n-octylamine. , 2-ethylhexylamine,
n-tetradecylamine, n-hexadecylamine, n
-Octadecylamine, aniline, 4-biphenylamine, p-phenetidine, p-anisidine, p-dodecylaniline, cyclopentylamine, cyclohexylamine, dihydroabietylamine, 3,5,5-trimethylhexylamine, euleramine, n-dodecylamine Etc.

Isocyanates used for these reactions include 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 3,3'-dimethyl-4,4 'biphenylene diisocyanate. , Hexamethylene diisocyanate and the like.

The alkyl diphenyl ether oil, which is an essential component of the present invention, is synthesized by addition reaction of 1 mol of diphenyl ether and 1 to 3 mol of α-olefin having 10 to 22 carbon atoms by a usual Friedel-Crafts reaction. . That is, a specified amount of diphenyl ether and aluminum chloride are put into a reaction vessel and heated and stirred at 80 to 90 ° C. to dissolve the aluminum chloride. Then, a prescribed amount of α-olefin is added dropwise to carry out the addition reaction. The reaction temperature is 80 to 120 ° C. After completion of dropping, aging and stirring are performed for a certain period of time, and then water is added to decompose aluminum chloride. After that, washing with a 5% aqueous solution of sodium carbonate and water was repeated several times, and finally, fractionation was performed by distillation.

The properties of the alkyl diphenyl ether oil thus obtained differ depending on the number of carbon atoms and the number of moles of the α-olefin used. Also, in terms of appearance, there is a difference in the hue from the colorless to brown transparent liquid. The main characteristics of the alkyl diphenyl ether oil are as follows.

1) Alkyl diphenyl ether oil has excellent physical properties as a lubricating oil, that is, a high viscosity index, a low pour point, and a high pour point, by appropriately adjusting the number of side chain carbon atoms and the number of added moles of the α-olefin used. A material having flammability and appropriate viscosity and specific gravity characteristics is obtained. Therefore, it is possible to select the one having the characteristics according to the application. 2) Alkyl diphenyl ether oil has excellent heat resistance and has a characteristic that sludge is not generated even when left at 170 ° C. for 30 days or more under high temperature. 3) Alkyl diphenyl ether oil has excellent oxidative stability as compared with conventional petroleum-based and synthetic lubricating oils. 4) Alkyl diphenyl ether oil has almost the same lubricity as petroleum-based lubricating oil, and various additives can be freely used. 5) Alkyl diphenyl ether oil has excellent electrical characteristics, especially a large dielectric constant, and is excellent in vacuum characteristics.

In the present invention, the alkyl diphenyl ether oil having such excellent properties occupies a major part of the base oil component, and the thickener has good lubricating properties under the condition of high speed rotation. By using a diurea compound that exhibits a long life even at high temperatures and combining them, an excellent lubricating grease having a long life even under the condition of high-speed rotation and at a high temperature was obtained. .

Thus, in order to obtain a lubricating grease having a long life under high-speed rotation conditions, it is necessary to contain 50% or more of alkyl diphenyl ether oil, but a base that can be mixed with this and used. Examples of the oil include mineral oils, animal and vegetable oils, various diesters, tetraesters and pentaerythritol esters, poly α-olefins, silicone oils, fluorine oils and the like.

To obtain the lubricating grease of the present invention, 3
A solution of seed amines in a base oil is placed in a solution of diisocyanate in the base oil and these are vigorously stirred to accelerate the reaction. Then, after heating and stirring are continued up to a temperature of 170 ° C., the maximum heating temperature is maintained for a certain period of time, and then the heating is stopped. After that, it is left to cool to room temperature, but 1
Necessary additives are added in the vicinity of 00 ° C., and processing such as dissolution and mixing is performed. It can be easily obtained by a general production method in which it is left to cool to room temperature and then finished with a three-stage roll mill.

[0018]

The alkyl diphenyl ether oil, which constitutes the main part of the present invention, has a very small evaporation loss under high temperature conditions and is also excellent in oxidative stability, and also has little sludge formation and lubricating performance. Also has excellent characteristics in terms of. For this reason, the grease composition of the present invention, which is intended to constitute the major part of the base oil, is the alkyl diphenyl ether oil, which has excellent properties in many aspects, and has been widely used in the past. Compared with conventional greases that have used conventional mineral oils, various esters, poly-α-olefin oils, etc. as the main components of the base oil, they have remarkably long life characteristics under high temperature conditions.

However, if only the base oil retains the heat resistance, long-life performance as grease and good lubrication characteristics at high speed cannot be obtained, and the combination with the thickener is an important issue. Becomes For example, when lithium 12-hydroxystearate, which has been widely used as a thickener in the past, is used as a thickener, even if an alkyldiphenyl ether oil is used as the base oil, the grease will not be removed at high temperatures. However, the grease will change to a fluid state, which will cause it to be washed away from the lubricated part, and the heat resistance performance of the grease will be poor, so long-life performance cannot be exhibited.

Organized bentonite has been widely used as a heat-resistant thickening agent, but when it is used in combination with an alkyl diphenyl ether oil, on the contrary, it hardens at high temperature. As a result, this causes poor lubrication, which makes it impossible to exhibit long-life performance. The thickener component proposed by the present invention is a diurea compound obtained by reacting three kinds of amines having different structures with diisocyanate, but a grease using a urea compound other than the present invention as a thickener is It has a long life, but it does not give good results in lubrication under high speed rotation.

With respect to the lubrication mechanism under high speed rotation of the bearing, there are many unknowns, but theoretical elucidation has not been possible.
The properties of the components that make up the thickener appear to play an important role in exerting these functions. In the grease, these thickener components have a three-dimensional network structure in the base oil, retain the oil by their capillary force, and have a semi-solid state at room temperature. Such a structure changes variously as the temperature rises, and the bonding state also changes remarkably. This situation is
It can be grasped by checking the transition temperature, which indicates the change of the crystalline state, by differential thermal analysis. This transition temperature is greatly related to the constituents of the thickener, but is slightly changed depending on the type and concentration of the coexisting base oil. The grease filled in the bearing rises in temperature due to repeated disconnection and metal contact under the conditions of load and high-speed rotation. Repeating cycles such as extremely low temperatures.

The urea grease other than the present invention causes a large change in the entire structural surface while continuing such recycling, which causes a phenomenon such as oil separation and curing, which is a cause. This results in the worst situation of poor lubrication.

The composition of the thickener component of the present invention is characterized in that three kinds of amines having different structures are constituted in an optimum ratio and they are reacted with isocyanate to form a diurea compound. . Of these three amines, the part formed by the compound of linear aliphatic amine and isocyanate has the property of being easily dissolved in the base oil and has inferior heat resistance. When the temperature rises, it dissolves easily or melts into the base oil, and they flow into the bearing rolling surface, forming a strong lubricating film on the surface. This property exerts the performance of maintaining good lubricity under the condition of high speed rotation. However, if this alone is used, grease will be washed out from the bearing and a very good result cannot be obtained in terms of lubrication performance.However, in order to prevent this, an aromatic amine with good performance in terms of heat resistance is used. In combination, the diurea compound formed by the reaction of this with isocyanate exerts the performance of softening runoff and heat resistance, corrects the defects of the aliphatic amine component, and retains the heat resistance of grease. Becomes Cycloalkyl group-based amine which is another component, and the portion constituted by the diurea compound produced by the reaction with isocyanate, for the purpose of fusing the constituent components of aliphatic and aromatic,
It is a combination of them and has a role of maintaining good performance as a lubricating grease.

Based on such a concept, the constitution of the thickener portion forming the lubricating grease of the present invention is such that three amines are individually bonded to diisocyanate,
Two different amines, such as those having a structure in which they are bonded to diisocyanate, are mixed and coexist in the system forming the thickener part.
As a desirable form, it is necessary to study the compounding aspect and the production method so that the compounds in which two different amines are bonded to the diisocyanate are present in the system as much as possible. As a result of diligent studies, the inventors have succeeded in finding the optimum blending ratio and the production method in the present invention, and have an excellent lubricating grease composition capable of achieving good lubrication performance at high speed and long life. Is a successful one.

[0025]

The present invention will be specifically described by the following examples and comparative examples. In each of the examples and comparative examples, grease was manufactured based on the compounding components shown in Tables 1 to 3, and the physical properties and performances were evaluated by the methods described below. Mixing consistency ... According to JIS-K-2220. Drop point: According to JIS-K-2220. Bearing lubrication life test ... According to ASTM-D-1741.
However, the test temperature was 150 ° C. NTN CRC type grease life tester ... ASTM-D
According to -3336-75, however, the test temperature was 150 ° C.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

Examples I to VII and Comparative Examples 1 to 12 Half the amount of the base oil shown in Table 1 and the total amount of the isocyanate were placed in a reaction vessel and heated to 50 to 60 ° C. Then, in a separate container, the three and two amines were taken in the remaining half amount of the base oil and dissolved by heating at 70 to 80 ° C., this solution was carefully added into the reaction container, and these were vigorously stirred to carry out the reaction. Promote. In this reaction, the temperature of the reaction product rises because of the exothermic reaction, but in this state, stirring, pipe circulation and the like are performed for a sufficient reaction and uniform dispersion. While the pipe circulation continues intermittently, the temperature is raised after this,
After holding at 180 ° C. for about 1 hour, it was cooled. After cooling to room temperature, it was finished with a three-stage roll mill to obtain the target grease.

The properties of various raw materials shown in Examples and Comparative Examples are as follows. Alkyl diphenyl ether oil-Kinematic viscosity <40 ° C> -67cst-Flash point-
--250 ° C Paraffin mineral oil-Kinematic viscosity <40 ° C ---- 67.2cst-Flash point-
--240 ° C. Pentaerythritol ester-Kinematic viscosity <40 ° C .---- 27.8 cst-Flash point-
--270 ° C poly-α-olefin oil-Kinematic viscosity <40 ° C>-33.0cst-Flash point-
--244 ° C

As shown in the examples, the grease of the present invention was 2 times in the lubrication life test at 150 ° C.
In a CRC type grease life test, which has a long life of 000 hours or more and evaluates high-speed lubrication performance, it also showed a long life of 2,000 hours or more at 150 ° C. Further, even if the paraffinic mineral oil is mixed in the base oil in an amount of 25 to 50%, the one using the thickener of the present invention has a relatively long life of 1800 hours and 1600 hours in the lubrication life test at 150 ° C. Showing the time.

Comparative Examples 1 to 3 show examples in which a base oil other than alkyl diphenyl ether oil was used as the base oil, and Comparative Examples 4 to 6 used alkyl diphenyl ether oil as the base oil, and As the thickener component, although three kinds of amines are combined, an example is shown in which the compounding ratio thereof is out of the range claimed by the present invention. In each case, the result of the lubrication life test showed a short value. Further, Comparative Examples 7 to 12 show examples of a type in which a thickener is combined with one or two amines, and a urea type lubricating grease which is currently commercially available. In either case, the result of the life test showed a short life, and it can be said that the superiority of the lubricating grease of the present invention was proved here as well.

[0033]

The lubricating grease composition of the present invention comprises, as a base oil, an alkyldiphenyl ether oil as an essential component, and as a thickener component, three amines in combination within a specific range. It was prepared using a manufacturing method that forms a compound in the desired form upon reaction with an isocyanate.

As is clear from the above description, the lubricating grease of the present invention thus prepared exhibits a long life at high temperatures and exhibits a long life even in a high speed / high temperature life test. The excellent effect was obtained.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication location C10N 30:08 40:02 50:10 (72) Inventor Yasuyuki Tsuji 2523 Harajima, Kumana City, Mie Prefecture 1

Claims (1)

[Claims] 1. An alkyldiphenyl ether oil is used as a main component of a base oil portion, and a thickener is represented by the following general formula R1-NHCONH-R2-NHCONH-R3 (R2 in the above formula is a tolylene group or a diphenylmethane group). Or a dimethylbiphenylene group, R1 and R3 each represent a linear saturated alkyl group having 6 to 18 carbon atoms, a cycloalkyl group and an aromatic hydrocarbon group, the proportion of which is linear saturated alkyl. 25-45 mol% of groups,
50-70 mol% of cycloalkyl groups and 5 of aryl groups
Is comprised within the range of ˜25 mol%. ] The diurea compound represented by these is mix | blended with 2-34 weight part with respect to 100 weight part of base oils, The grease composition for rotary machine bearings characterized by the above-mentioned.