JP2011052048A - Grease composition and roller bearing encapsulating the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grease composition having fluidity even at low temperature while enhancing lubricating performance at high temperature and/or to provide a roller bearing suitably used at from high temperature to low temperature, especially a roller bearing for engine assist in a car such as an automobile. <P>SOLUTION: In the grease composition including a base oil and a thickener, an alkyl diphenyl ether oil containing an oil formed by mixing a linear chain ether oil wherein a linear alkyl chain is bonded to diphenyl ether in a branched ether oil wherein a hydrocarbon group is added to an α-position of an alkyl chain bonded to diphenyl ether at a prescribed rate or a poly-α-olefin oil and having 60 to 110 mm<SP>2</SP>/s kinematic viscosity at 40°C is used as the base oil, and a predetermined diurea compound of 5 to 40 mass% is contained as the thickener. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a grease composition and a rolling bearing in which the grease composition is enclosed, and in particular, grease suitable for lubrication of rotating parts and sliding parts of equipment used at high temperatures and high speeds such as automotive electrical parts and auxiliary machine parts. The present invention relates to a rolling bearing that can be suitably used for a composition and a rotating part.

  In recent years, particularly in passenger cars, the engine room space has been reduced due to demands for smaller and lighter automobiles and larger living spaces, and further reductions in the size and weight of engine accessories disposed in the engine room have been promoted. In addition, the engine room is being sealed due to a demand for improvement in quietness, and the temperature in the engine room becomes higher. Therefore, each component in the engine room is required to withstand high temperatures. For example, a rolling bearing of an engine auxiliary machine, which is one of components arranged in an engine room, has been used at a temperature of 130 to 150 ° C. until now, but can withstand a high temperature of 160 to 180 ° C. in recent years. There is a need for such rolling bearings.

  Furthermore, with the global expansion of vehicle models by vehicle manufacturers, there is an increasing demand for various parts that can withstand various specifications such as tropical and cold regions. The low temperature characteristics, that is, the smooth rotation of the rolling bearing at a low temperature of the bearing, that is, the securing of the low temperature fluidity of the grease composition to be enclosed has also been required at the same time.

  As a prior art, there is JP-A-11-181465. This is to achieve improved heat resistance by blending a grease composition with a base oil in which at least one of mineral oil or synthetic oil and fluorine oil are mixed, and a thickener made of a urea compound. However, the fluidity aspect of grease at low temperatures has not been studied.

JP 11-191465 A

  An object of the present invention is to provide a grease composition having fluidity even at low temperatures while improving lubrication performance at high temperatures, and / or a rolling bearing that can be suitably used from high temperatures to low temperatures, In particular, it is to provide a rolling bearing for an engine accessory in a vehicle such as an automobile.

In order to solve the above problems, a first invention is a grease composition comprising a base oil and a thickener, and has the following composition.

In the general formulas (I) and (II), R1 and R2 may be the same or different and each represents an alkyl chain having 10 to 20 carbon atoms.
In the general formulas (III) and (IV), R3 and R4 may be the same or different and each represents an alkyl chain having 7 to 20 carbon atoms. The number of carbon atoms is preferably 8 to 20, more preferably 12 to 14, and a linear structure is more preferable.
In general formula (V), R5 represents hydrogen or an alkyl group. Preferably it is C3-C8 and it is preferable that it is a linear structure.

That is, the base oil in the grease composition of the first invention is an oil represented by the general formula (I) in which a hydrocarbon group is added to the α-position of the alkyl chain bonded to diphenyl ether (hereinafter referred to as a branched ether oil). And an oil represented by the above general formula (II) in which a linear alkyl chain is bonded to diphenyl ether (hereinafter referred to as a linear ether oil) in a weight ratio of 5:95 to 95: 5, The alkyl diphenyl ether oil represented by the general formulas (III) and (IV) or the polyalphaolefin oil represented by the general formula (V) is mixed at a weight ratio of 20:80 to 80:20, The kinematic viscosity of the base oil at 40 ° C. is 60 to 110 mm ² / s.

  Further, the thickener in the grease composition of the first invention is a mixture of diurea compounds represented by the following general formulas (6) to (8), and 5 to 40 relative to the total amount of the grease composition. It is contained in the range of% by weight.

  In the general formulas (5) to (8), R2 represents an aromatic ring-containing hydrocarbon group having 7 to 12 carbon atoms, R2 represents a divalent aromatic ring-containing hydrocarbon group having 6 to 15 carbon atoms, and R3 represents It represents a cyclohexyl group or an alkylcyclohexyl group having 7 to 12 carbon atoms, and the value of [number of moles of R1 / (number of moles of R1 + number of moles of R3)] in the mixture is 0.5 to 1.0.

  According to the grease composition of the first aspect of the invention, in particular, it is possible to use a base oil having a relatively low viscosity without impairing the heat resistance of the grease composition, Since a thickener that is not easily affected by the above is used, a grease composition that can be used stably from a high temperature to a low temperature can be obtained.

In the base oil of the grease composition of the first invention, if the kinematic viscosity at 40 ° C. exceeds 110 mm ² / s, the stirring resistance of the base oil tends to increase when encapsulated in the rolling bearing.・ It is not preferable because the rotational torque increases excessively. In addition, the fluidity of the grease composition at low temperatures becomes insufficient, and abnormal noise may occur when starting the rolling bearing at low temperatures. However, if the kinematic viscosity of the base oil is less than 60 mm ² / s at 40 ° C., it is not appropriate because of problems such as evaporation loss at high temperatures and securing the thickness of the oil film. That is, for example, in the case of a rolling bearing, if the viscosity of the base oil is too low, it may be difficult to form a lubricating oil film sufficient to avoid metal contact between the raceway surface and the rolling element during rotation of the bearing at a high temperature. . In order to make these problems less likely to occur, the kinematic viscosity of the base oil at 40 ° C. is preferably 70 to 100 mm ² / s.

  The grease composition of the second invention is characterized in that the penetration degree is 230 to 330 in the grease composition of the first invention. Preferably, the penetration is in the range of 250-300. When the blending degree is less than 230, a sufficient lubricating effect cannot be expected.

  In order to further improve various performances of the grease composition, various additives may be mixed as desired. 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 alkyls and alkenyl succinates, alkenyl succinate derivatives, partial esters of polyhydric alcohols such as sorbitan monooleate, and the like. 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. These additives may be used alone or in combination 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. Moreover, the manufacturing method of a grease composition is not specifically limited.

  A third invention is a rolling bearing in which the first or second grease composition is encapsulated, and the rolling bearing in which such a grease composition is encapsulated has excellent lubricity and a long life even at high temperatures. Therefore, it can be suitably used for rotating parts of equipment used under high-temperature and high-speed conditions such as automobile engine accessory parts such as alternators, electromagnetic clutches and idler pulleys. Furthermore, the rolling bearing encapsulating the grease composition of the present invention exhibits excellent performance even at low temperatures.

  The grease composition of the first or second invention is not limited to the above and can be applied to various rolling devices, sliding devices, rolling portions, sliding portions, and the like. For example, in addition to rolling bearings, it can be suitably used for ball screws, linear guide devices, linear motion bearings, and the like.

  According to the present invention, a grease composition having stable performance from a high temperature to a low temperature can be obtained. In addition, when the grease composition is enclosed in a rolling bearing, a rolling bearing having stable performance from high temperature to low temperature can be obtained.

It is a longitudinal cross-sectional view which shows the structure of the ball bearing which is one Embodiment of the rolling bearing which concerns on this invention. It is sectional drawing which shows the structure of the bearing life test machine which evaluates the seizure property of a grease composition.

  This embodiment shows an example of the present invention, and the present invention is not limited to the embodiment. For example, the types of base oil and thickener are not limited to those described above, and various additives may be added to the grease composition G. In this embodiment, a deep groove ball bearing has been described as an example of a rolling device including a rolling bearing. However, the present invention can be applied to various types of rolling bearings. For example, radial rolling bearings such as angular contact ball bearings, self-aligning ball bearings, cylindrical roller bearings, tapered roller bearings, needle roller bearings, and self-aligning roller bearings, and thrust-type bearings such as thrust ball bearings and thrust roller bearings It is a rolling bearing. Further, the present invention can be applied not only to rolling bearings but also to various other types of rolling devices. For example, ball screw, linear guide device, linear motion bearing, etc.

  Grease compositions as examples and comparative examples were prepared by a predetermined method. The grease compositions of Examples 1 to 5 are as shown in Table 1, and the grease compositions of Comparative Examples 1 to 4 are as shown in Table 2. A thickener composed of a diurea compound, a base oil composed of a synthetic oil, Contains. As an additive, any of the grease compositions includes 2% by weight of an amine-based antioxidant, 1% by weight of a calcium sulfonate-based rust inhibitor, and 0.05% by weight of benzotriazole. And a metal deactivator.

  In addition, the numerical value described in the column of the kind of thickener and the kind of base oil has shown the quantity ratio (weight%) of each component in the whole thickener and base oil.

[Dynamic torque test at -40 ° C]
In the torque test at -40 ° C, grease is sealed in a deep groove ball bearing with an outer diameter of 62 mm, an inner diameter of 25 mm, and a width of 17 mm with a space volume of 30%. The outer ring temperature is -40 ° C, the radial load is 98 N, and the axial load is 98 N. , is rotated at a inner ring rotation speed 3000 min ^-1, the rotational torque was measured 5 minutes after start of rotation was dynamic torque. At this time, the dynamic torque in Comparative Example 1 was set to 1, and the dynamic torques of other Examples and Comparative Examples were shown in the form of ratios thereto.

[Baking life at 200 ° C]
A deep groove ball bearing with a metal shield having an inner diameter of 8 mm, an outer diameter of 22 mm, and a width of 7 mm is filled with the grease compositions of Examples 1 to 5 and Comparative Examples 1 to 4 so as to occupy 50% of the bearing space volume, and is shown in FIG. The seizure life was measured with such a bearing life tester based on ASTM D 1741. In the test, the inner ring was rotated at a rotational speed of 3000 mim ⁻¹ under conditions of a bearing temperature of 200 ° C. and an axial load of 98 N (other conditions conformed to ASTM D1741), and the temperature of the outer ring became 210 ° C. or more due to heat generation of the bearing. The time until is the seizure life. Relative comparison was performed with the seizure time of Comparative Example 1 as 1.

  The test results are as shown in Tables 1 and 2. The rolling bearings encapsulating the grease compositions of Examples 1 to 5 have a low torque at −40 ° C. and a long seizure life at 200 ° C., whereas the grease compositions of Comparative Examples 1 to 4 At least one of the low temperature torque and the seizure life at 200 ° C. is inferior in the rolling bearing encapsulating the.

  The grease composition of the present invention can be used as a grease composition suitable for lubrication of rolling parts or sliding parts in rolling devices such as rolling bearings or various mechanical devices. In addition, the rolling bearing in which the grease composition of the present invention is enclosed can be suitably used particularly from a high temperature to a low temperature as a rotation support member of an electrical component such as an automobile or an engine accessory.

1 Ball Bearing 10 Inner Ring 11 Outer Ring 13 Ball G Grease Composition

Claims (3)

In a grease composition comprising a base oil and a thickener,

[However, in the general formulas (I) and (II), R1 and R2 may be the same or different and each represents an alkyl chain having 10 to 20 carbon atoms.]
A mixture of the ether oil represented by the general formula (I) and the ether oil represented by the general formula (II) in a weight ratio of 5:95 to 95: 5;

[In the general formulas (III) and (IV), R3 and R4 may be the same or different and each represents an alkyl chain having 7 to 20 carbon atoms. ]
The ether oil represented by the general formula (III) or the general formula (IV), the ether oil represented by the general formula (V) or the poly-α-olefin is mixed at a weight ratio of 5:95 to 95: 5. A base oil having a kinematic viscosity at 40 ° C. of 60 to 110 mm ² / s,

[In General Formulas (5) to (8), R2 represents an aromatic ring-containing hydrocarbon group having 7 to 12 carbon atoms, R2 represents a divalent aromatic ring-containing hydrocarbon group having 6 to 15 carbon atoms, and R3 Represents a cyclohexyl group or an alkylcyclohexyl group having 7 to 12 carbon atoms, and the value of [number of moles of R1 / (number of moles of R1 + number of moles of R3)] in the mixture is 0.5 to 1.0. ]
A grease composition comprising a mixture of diurea compounds represented by the general formulas (5) to (8) as a thickener in an amount of 5 to 40% by mass based on the total amount of the grease composition.   The grease composition according to claim 1, wherein the grease composition has a penetration degree of 230 to 330.   A rolling bearing comprising the grease composition according to claim 1 enclosed therein.

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