JP2007186578A - Grease composition and roll bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grease composition and roll bearing, being equipped with a heat resistance capable of enduring the use under a severe high temperature environment over 180°C, also excellent in lubricating performance and load resistance, and especially suitable for an electric equipment and engine auxiliary machine, etc., of an automobile. <P>SOLUTION: This grease composition uses ether oil as base oil and an urea compound as a thickening agent, and also contains 0.1-10 mass% of at least 1 kinds of thiophenols and hindered amines as an antioxidant based on the total amount of the bas oil, or 0.1-10 mass% of at least 1 kinds of thiophenols and phosphorous acid esters based on the total amount of the base oil. The roll bearing obtained by sealing-in the grease composition is also provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is, for example, an electrical component for automobiles, an alternator that is an engine auxiliary machine, an intermediate pulley, an electromagnetic clutch for a car air conditioner, and the like, and a grease composition that is suitable for parts used at high temperatures and high speeds. It is related with the rolling bearing suitable for.

  Due to the spread of FF vehicles aimed at reducing the size and weight of automobiles, and due to the demand for expanding the living space, the engine room space has been reduced, and the above-mentioned electrical components and engine accessories have been reduced in size and weight. Further progress is being made, and higher performance and higher output are increasingly required for the components incorporated in the system. However, a reduction in output is unavoidable due to miniaturization, and for example, an alternator and an electromagnetic clutch for a car air conditioner compensate for the reduction in output by increasing the speed, and accordingly, the intermediate pulley is also increased in speed. Furthermore, since the engine room is being sealed due to a demand for improvement in quietness and the high temperature in the engine room is promoted, these parts are also required to withstand high temperatures.

  In addition, electric parts and engine auxiliary machines are required to be smaller and lighter and to be rotated at higher speeds. On the other hand, demands for resource saving and energy saving are high, and maintenance-free is also demanded. For this reason, rolling bearings to be incorporated are also required to have reliability and durability in addition to heat resistance. Specifically, it may be used in an environment where the bearing temperature exceeds 180 ° C., and in order to withstand such a high temperature environment, the present applicant also encloses a grease composition previously blended with a clay mineral. (For example, refer patent documents 1-3). In addition, as a grease composition considering heat resistance, a mixed oil of a polyol ester oil and an alkylphenyl ether oil is used as a base oil, and a dialkyldithiocarbamate compound and a hindered phenol compound are added as an antioxidant. A thing is also known (for example, refer patent document 4).

JP 2002-250353 A JP 2003-42166 A JP 2004-2696 A JP-A-8-188790

  Although the clay mineral greases and synthetic oil greases listed above are excellent in heat resistance, there is room for improvement in lubricity and load resistance. Therefore, the present invention has heat resistance that can withstand use even in a severe high temperature environment exceeding 180 ° C., and also has excellent lubrication performance and load resistance, and is particularly suitable for the above-described automotive electrical parts, engine auxiliary machines, and the like. An object of the present invention is to provide a grease composition and a rolling bearing.

In order to achieve the above object, the present invention provides the following grease composition and rolling bearing.
(1) An ether oil is used as a base oil, a urea compound is used as a thickener, and at least one of thiophenols and hindered amines as an antioxidant is 0.1 to 10% by mass of the total amount of the base oil, or thio A grease composition characterized by containing at least one of phenols and phosphites in an amount of 0.1 to 10% by mass based on the total amount of the base oil.
(2) As an antioxidant, both thiophenols and hindered amines are 0.1 to 10% by mass of the total amount of the base oil, or both thiophenols and phosphites are each 0.1% of the total amount of the base oil. The grease composition as described in (1) above, containing 1 to 10% by mass.
(3) A rolling bearing comprising the grease composition as described in (1) or (2) above.

  The grease composition of the present invention has a higher antioxidation performance and a higher heat resistance by a combination of ether oil and a specific antioxidant, and is usually obtained only by adding an antioxidant. Unusable wear resistance and load resistance are also added.

  In addition, the rolling bearing of the present invention has excellent heat resistance, wear resistance and load resistance due to the inclusion of the above grease composition, and can be used at high temperatures and high speeds such as automotive electrical parts and engine accessories. Can be suitably used for applications used in

  Hereinafter, the present invention will be described in detail.

In the grease composition of the present invention, ether oil is used as the base oil. Especially, since it is excellent in heat resistance, it is preferable to use alkyl diphenyl ether and polyphenyl ether individually or in mixture, respectively. Alkyldiphenyl ether is used as a base oil for grease around automobile engines and electrical equipment, and polyphenyl ether seems to be used in automotive ceramic turbines, turbo engines, cogeneration engines, jet engines, etc. Moreover, both are lubricating oils that are extremely excellent in heat resistance. The base oil desirably has a low viscosity in consideration of high-speed applications, and preferably has a kinematic viscosity at 40 ° C. of 15 to 100 mm ² / s.

  Moreover, although a urea compound is used as the thickener, a diurea compound having excellent heat resistance is preferred in view of durability at high temperatures. The blending amount of the thickener is not limited as long as it can form a gel structure with the base oil, but is preferably 5 to 30% by mass of the total amount of the grease composition. Further, the blending degree of the grease composition is preferably 200 to 350.

An antioxidant is added to the base oil, and it is added in any of the following forms (i) to (v).
(I) 0.1-10% by mass of thiophenols based on the total amount of base oil
(Ii) 0.1 to 10% by mass of hindered amines based on the total amount of base oil
(Iii) 0.1-10 mass% of phosphites with respect to the total amount of base oil
(Iv) 0.1-10% by mass of thiophenols based on the total amount of base oil and 0.1-10% by mass of hindered amines based on the total amount of base oil
(V) 0.1-10% by mass of thiophenols based on the total amount of base oil and 0.1-10% by mass of phosphites based on the total amount of base oil

  Thiophenols have a sulfur atom and a phenol group in the molecule, capture peroxy radicals to stop the chain reaction of oxidation (also called primary antioxidant function), and react with peroxides to prevent non-oxidation. It also has a function of generating free radicals and inactive substances (also called a secondary antioxidant function), and both functions exhibit particularly excellent antioxidant performance. In addition, thiophenols contribute to improvement of lubricity, wear resistance, and load resistance because sulfur atoms protect the surface of the lubrication site. As thiophenols, for example, 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] can be preferably used.

  The hindered amines have the above-described primary antioxidant function, and exhibit excellent antioxidant performance even when used alone. Examples of hindered amines include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate represented by the following formula (1), and bis (1,2,2,6, represented by the following formula (2). 6-pentamethyl-4-piperidyl) sebacate, tetraxy (2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate represented by the following formula (3), 4) decanedioic acid bis (2,2,6,6-tetramethyl-1 (octyloxy) -4-piperidinyl ester represented by the formula, 1,1-dimethylhydroxyperoxide, etc. can be preferably used. Since hindered amines also have light resistance (light resistance), deterioration of the grease composition due to ultraviolet rays or the like can be suppressed.

  Phosphites have the secondary antioxidant function described above, and exhibit excellent antioxidant performance even when used alone. Phosphites include tris (nonyl phenyl) phosphite, tris (mixed mono- and di-nonylphenyl) phosphite, diphenyl mono (2-ethylhexyl) phosphite, triisodecyl phosphite, diphenyl iso Decyl phosphite, tetraphenyltetra (tridecyl) pentaerythritol tetraphosphite and the like can be suitably used.

  The addition amount of thiophenols, hindered amines and phosphites is 0.1 to 10% by mass, more preferably 0.3 to 2% by mass, based on the total amount of the base oil. If the addition amount is less than 0.1% by mass, the desired effect cannot be sufficiently obtained, and if the addition amount exceeds 10% by mass, not only the effect is saturated, but also the thermal stability becomes inferior, which is practical. Not.

  Hindered amines and phosphites may be used alone, but hindered amines have only a primary antioxidant function, and phosphites have only a secondary antioxidant function. Therefore, both use together with thiophenols to have both a primary antioxidant function and a secondary antioxidant function, resulting in superior antioxidant performance and wear resistance due to thiophenols. And load resistance is also added.

  The grease composition of the present invention may contain various additives in addition to the above-mentioned blend depending on the purpose. For example, a rust inhibitor and an antiwear agent can be added so that it may become 1-10 mass% of the grease composition whole quantity.

  There is no restriction on the method of preparing the grease composition. For example, a diurea compound is synthesized in ether oil to which a predetermined amount of an antioxidant is added, and other additives are added as necessary to kneaders or roll mills. Can be stirred. At this time, heating is also effective.

  The present invention also provides a rolling bearing in which the above grease composition is enclosed. There are no restrictions on the structure and type of rolling bearings, but the above-mentioned grease composition has a good balance of heat resistance, wear resistance and load resistance, so rolling bearings used in high temperature and high speed environments are suitable. is there. For example, rolling bearings incorporated in electrical components of automobiles, alternators and intermediate pulleys that are engine auxiliary machines, electromagnetic clutches for car air conditioners, and the like can be exemplified.

(Test-1: Examples 1-6, Comparative Examples 1-6)
As shown in Table 1, a test grease was prepared by blending a base oil, a thickener and an additive. In addition, “LB68” (68 mm ² / s @ 40 ° C.) manufactured by Matsumura Oil Research Co., Ltd. is used as the alkyl diphenyl ether of the base oil, and “S-3103” (tetraphenyl ether) manufactured by Matsumura Oil Research Co., Ltd. is used as the polyphenyl ether. , 120 mm ² / s @ 40 ° C.) “Unistar H-481R” (64 mm ² / s @ 40 ° C.) manufactured by Nippon Oil & Fats Co., Ltd. as a hindered ester, manufactured by ExxonMobil Co., Ltd. as PAO (poly α-olefin oil) “Spectracin 10” (66 mm ² / s @ 40 ° C.) and Shin Nippon Oil Co., Ltd. turbine oil (68 mm ² / s @ 40 ° C.) were used as mineral oils, respectively. Further, “Adeka Stub A-57” manufactured by Asahi Denka Co., Ltd. as the hindered amine of the antioxidant, and 2,2-thio-diethylenebis [3- (3,5-di-) manufactured by Ciba Specialty Chemicals Co., Ltd. as the thiophenol. Tert-butyl-4-hydroxyphenyl) propionate], 2,5-di-tert-butyl-4-made by Tokyo Chemical Industry Co., Ltd. as PAN (phenyl-α-naphthylamine), and Nippon Kasei Co., Ltd. as phenol. Methylphenol was used for each.

Each test grease was subjected to the following (1) heat resistance test, (2) wear resistance test, and (3) seizure life test.
(1) Heat resistance test About 10 g of the test grease was placed in a petri dish, placed in a constant temperature bath at 200 ° C. and allowed to stand for 300 hours. After standing, the evaporation amount and total acid value of the test grease were measured. The results are shown in Table 1.
(2) Abrasion resistance test A test grease is applied on a mirror-finished flat plate, and a bearing steel ball having a diameter of 10 mm is placed thereon. At an ambient temperature of 80 ° C., an amplitude of 0.7 mm and a vibration frequency of 10 Hz are applied while applying a load of 59 N. After rocking for 10 minutes, the trace diameter of the flat plate due to wear was measured. The test was performed 3 times, and the average value was obtained. The results are shown in Table 1.
(3) Seizure life test Test grease is sealed in a ball bearing with heat-resistant rubber seal “6305 (outer diameter 62 mm, inner diameter 25 mm, width 17 mm)” manufactured by NSK Ltd. so as to be 30% of the space volume. A test bearing was prepared. When the test bearing is continuously rotated under the conditions of an outer ring temperature of 180 ° C., a radial load of 98 N, an axial load of 98 N, and an inner ring rotational speed of 15000 min ⁻¹ , a seizure life occurs when a temperature rise and a torque rise (motor current value) occur. And time until that time was measured. The test was performed 3 times, and the average value was obtained. The results are shown in Table 1 as relative values with the result of Comparative Example 1 being 1.

  As shown in Table 1, according to the present invention, the test grease of the example in which ether oil was used as the base oil and at least one of thiophenol and hindered amine was added as the antioxidant was compared with the test grease of the comparative example. The amount of evaporation is small and the heat resistance is excellent, and the wear resistance is also excellent. The seizure life is substantially extended from two to three times. Moreover, the more excellent result was obtained by using together thiophenol and a hindered amine as antioxidant like Example 1,2.

(Test-2: Examples 7-12, Comparative Examples 7-12)
As shown in Table 2, a test grease was prepared by blending base oil, thickener and additives. The same base oil and other antioxidants as those used in Test-1 were used except for the tris (nonyl phenyl) phosphite manufactured by Asahi Denka Co., Ltd. as an antioxidant phosphite.

  Each test grease was subjected to (1) heat resistance test, (2) wear resistance test, and (3) seizure life test in the same manner as in test-1. The results are shown in Table 2.

  As shown in Table 2, the results are substantially the same as in Test-1, and according to the present invention, ether oil is used as the base oil, and at least one of thiophenol and phosphite, preferably both, is added as the antioxidant. It turns out that it comes to be excellent in heat resistance, abrasion resistance, and seizure resistance.

Claims (3)

  Ether oil as a base oil, urea compound as a thickener, and as an antioxidant, at least one of thiophenols and hindered amines is 0.1 to 10% by mass of the total amount of the base oil, or thiophenols and A grease composition comprising at least one phosphite ester in an amount of 0.1 to 10% by mass based on the total amount of the base oil.   As an antioxidant, both thiophenols and hindered amines are 0.1 to 10% by mass of the total amount of the base oil, or both thiophenols and phosphites are 0.1 to 10% of the total amount of the base oil. 2. The grease composition according to claim 1, wherein the grease composition is contained by mass%.   A rolling bearing comprising the grease composition according to claim 1 or 2 enclosed therein.