JP2005105238A - Grease composition for automotive electrical equipment and auxiliary machine and rolling bearing filled with the grease composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grease composition having excellent anti-seizing properties, even at a high temperature of approximately 180°C, without making an unusual sound at an extremely low temperature of -40°C, further having an excellent corrosion-resisting performance, and especially suitable for parts of electrical equipment, an engine auxiliary machine, etc., and to provide a rolling bearing. <P>SOLUTION: This grease composition for the automotive electrical equipment and auxiliary machine contains a base oil which contains an aromatic ester oil in an amount of ≥30 mass% based on the total amount of the base oil, and further contains a diurea compound which acts as a thickening agent and is expressed by general formula: R8-NHCONH-R9-NHCONH-R10 (R9 is a 6-15C aromatic hydrocarbon residue; and R8 and R10 are identical to or different from each other, and are each an aliphatic hydrocarbon residue, an alicyclic hydrocarbon residue or a condensed ring) in an amount of 5-35 wt% based on the total amount of the grease compound. Further, the rolling bearing which is filled with the grease composition is provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is used under high temperature, high speed, high load and severe vibration conditions such as an automobile electrical component, an alternator and intermediate pulley as an engine auxiliary machine, an electromagnetic clutch for a car air conditioner, etc., and further -40 ° C. The present invention relates to a grease composition used for parts that require fluidity at extremely low temperatures, and a rolling bearing in which the grease composition is enclosed.

  Due to the spread of FF (front engine front drive) vehicles aimed at reducing the size and weight of automobiles, and due to the desire to expand the living space, the engine room space has been reduced. Machines are becoming smaller and lighter, and there is an increasing demand for higher performance and higher output for each component. 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.

  Various proposals have been made to improve the seizure life at high temperatures, and greases containing a urea compound as a thickener in a base oil containing trimellitic ester oil are widely used (for example, Patent Document 1, Patent Document 2, and Patent Document 3). In addition, in rolling bearings used for these applications, it is necessary to take measures against a peeling phenomenon accompanied by a change in the structure of the transfer surface. For example, a method of adding a metal passivator such as nitrous acid has been proposed. . (See Patent Document 4 and Patent Document 5)

Japanese Patent Publication No. 7-45677 Japanese Patent No. 3290010 Japanese Patent No. 3330755 JP 2002-195277 A JP 2003-13973 A

  Automobiles are used in various countries around the world, and their usage environments are diverse. The required characteristics are also varied accordingly. For example, in cold regions, there is a high demand for noise generation due to insufficient fluidity of the lubricant when starting the engine, and in the rainforest area and areas close to the ocean, the humidity and salinity in the atmosphere are high, so there is a demand for rust prevention. Is expensive.

  However, no grease that can sufficiently cope with such various demands has been obtained yet. Therefore, the present invention does not generate abnormal noise even at an extremely low temperature of −40 ° C., has excellent seizure resistance even at a high temperature close to 180 ° C., and is excellent in peeling resistance and further rust prevention performance. In particular, it is an object of the present invention to provide a grease composition and a rolling bearing suitable for the above-described electrical components and engine accessories.

  As a result of diligent studies to solve the above problems, the present inventors have found that diurea compounds having an alicyclic hydrocarbon group can be combined with a base oil containing an aromatic ester oil from a very low temperature. It has been found that excellent lubrication performance is exhibited over a wide temperature range up to a high temperature, no abnormal noise is generated at low temperatures, and the seizure performance of the bearing can be greatly improved, and the present invention has been completed.

That is, the present invention provides a base oil containing 30% by mass or more of an aromatic ester oil based on the total amount of the base oil and a diurea compound represented by the following general formula as a thickener in an amount of 5 to 35% by mass based on the total amount of the grease composition. Provided is a grease composition for an automotive electrical accessory, characterized by containing.
R8-NHCONH-R9-NHCONH-R10
(In the formula, R9 is an aromatic hydrocarbon group having 6 to 15 carbon atoms, and R8 and R10 are an aliphatic hydrocarbon group, an alicyclic hydrocarbon group or a condensed ring, which may be the same as or different from each other. .)

  Further, the present invention provides the above grease composition for automotive electrical equipment, which contains at least one of carbon black and carbon nanotubes as conductive powder for imparting conductivity. Furthermore, as a rust inhibitor, a total of two or more selected from a rust inhibitor made of carboxylic acid or carboxylate, an ester rust inhibitor, and an amine rust inhibitor is 0.2 relative to the total amount of the grease composition. It is preferable to contain 10 to 10% by mass, and 0.1 to 9.9% by mass by itself, thereby providing sufficient rust prevention. Moreover, these rust preventive agents do not have an adverse effect on the environment.

  In addition, the present invention is characterized in that a plurality of rolling elements are rotatably held by a cage between an inner ring and an outer ring, and the above-mentioned grease composition for automotive electrical equipment is enclosed. Provide rolling bearings.

  According to the present invention, there is no abnormal noise even at an extremely low temperature of −40 ° C., and it has excellent seizure resistance even at a high temperature close to 180 ° C., and further has excellent peeling resistance and rust prevention performance. An auxiliary grease composition is provided. Further, according to the present invention, a rolling bearing suitable for an electrical component, an engine accessory, or the like is provided.

  Hereinafter, the grease composition for automobile electrical accessory of the present invention (hereinafter simply referred to as “grease composition”) and the rolling bearing will be described in detail.

(Grease composition)
[Base oil]
In the grease composition of the present invention, the base oil contains an aromatic ester oil. Among aromatic ester oils, trimellitic acid ester oil represented by the following formula (I) is preferable.

  In formula (I), R1, R2, and R3 are saturated or unsaturated linear or branched hydrocarbon groups, which may be the same as or different from each other. Moreover, it is preferable that carbon number is 6-10.

  Pyromellitic acid ester oils represented by the following formulas (II) and (III) are also preferred as aromatic ester oils.

  In the formulas (II) and (III), R4, R5, R6 and R7 are saturated or unsaturated linear or branched hydrocarbon groups which may be the same as or different from each other. Moreover, it is preferable that carbon number is 6-10.

  Conventionally, polyphenyl ether oil, silicone oil, fluorine oil, and the like are known as lubricating oils having excellent heat resistance. However, all of these lubricating oils are very expensive, and silicone oil and fluorine oil generally have a problem of poor lubricity. On the other hand, the aromatic ester oil has the advantages of being relatively inexpensive and having excellent heat resistance, oxidation resistance, wear resistance, and the like. In particular, trimellitic ester oil and pyromellitic ester oil represented by formulas (I) to (III) and having a hydrocarbon group having 6 to 10 carbon atoms have a low pour point and a high viscosity index. It is suitable for automotive electrical equipment that requires a wide operating temperature from extremely low to high temperatures. In particular, trimellitic ester oil is preferred because of its low pour point.

  Such trimellitic acid ester oil and pyromellitic acid ester oil having a hydrocarbon group having 6 to 10 carbon atoms are also available from the market, and “Trimex T-08” manufactured by Kao Corporation as trimellitic acid ester oil. , “Trimex N-08”, “Adeka Prover T-45”, “Adeka Prover T-90”, “Adeka Prover PT-50” manufactured by Asahi Denka Co., Ltd. “EMKARATE 8130”, “ Examples of pyromellitic acid ester oils such as “EMKARATE 9130” include “Adeka Prover LX-1891” and “Adeka Prover LX-1892” manufactured by Asahi Denka Co., Ltd.

  The content of the aromatic ester oil is preferably 30% by mass or more of the total amount of the base oil. When the content of the aromatic ester oil is less than 30% by mass, seizure at high temperatures is likely to occur, and furthermore, the wear resistance is not sufficiently exhibited. Examples of the lubricating oil that can be used in combination include mineral oil, fluorine oil, silicone oil, synthetic hydrocarbon oil, ether oil, ester oil other than aromatic ester oil, and glycol oil. Among these, those having a low pour point and excellent heat resistance and oxidation resistance are preferred, and synthetic hydrocarbon oils, ether oils and ester oils are preferred. Specifically, poly-α-olefin oils as synthetic hydrocarbon oils, alkyl diphenyl ethers, alkyl triphenyl ethers, etc. as ether oils, diester oils, neopentyl type polyol ester oils and complex ester oils thereof as ester oils, etc. Each can be mentioned. These may be used alone or in appropriate combination. Above all, in addition to low-frequency fluidity considering abnormal noise generation at extremely low temperatures, considering the improvement in lubrication performance and seizure life under high temperature, high speed, high load and vibration, conditions such as pentaerythritol ester oil The combined use with polyol ester oil, poly-α-olefin oil or alkyldiphenyl ether oil is preferred.

The base oil preferably has a kinematic viscosity at 40 ° C. of 30 to 150 mm ² / s, and more preferably 40 to 130 mm ² / s in view of low temperature fluidity. Most preferably, it is 40-100 mm < ² > / s.

[Thickener]
In the base oil, a diurea compound represented by the following formula (IV) is blended as a thickener.
R8-NHCONH-R9-HNOCHN-R10 (IV)

  In the formula (IV), R9 is an aromatic hydrocarbon group having 6 to 15 carbon atoms, and R8 and R10 are hydrocarbon groups or condensed ring hydrocarbon groups, which may be the same as or different from each other. In R8 and R10, the hydrocarbon group may be either an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and the condensed ring hydrocarbon group preferably has 9 to 19 carbon atoms. R8 and R10 preferably have at least an alicyclic hydrocarbon group or an aliphatic hydrocarbon group. A diurea compound having an alicyclic hydrocarbon group is superior in heat resistance as compared to a diurea compound having an aliphatic hydrocarbon group. Compared to a diurea compound having an alicyclic hydrocarbon group, a diurea compound having an aliphatic hydrocarbon group has an advantage that the grease has excellent fluidity when used as a thickener. In addition, the diurea compound having an alicyclic hydrocarbon group or an aliphatic hydrocarbon group has a larger surface area per unit volume due to the difference in fiber shape compared to the diurea compound having an aromatic hydrocarbon group. High thickening effect. Therefore, when compared at the same consistency, diurea compounds having aliphatic hydrocarbon groups or alicyclic hydrocarbon groups are used in a smaller amount than diurea compounds having aromatic hydrocarbon groups. The seizure resistance can be improved.

  In the diurea compound represented by the formula (IV), the monoamine having R8 or R10 in the skeleton is reacted at a ratio of 2 mol in total with 1 mol of diisocyanate having R9 in the skeleton in the base oil. Is obtained.

  As the diisocyanate having R9 in the skeleton, diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, biphenylene diisocyanate, dimethyldiphenylene diisocyanate, or alkyl-substituted products thereof can be suitably used.

As monoamines having a hydrocarbon group in the skeleton as R8 or R10, aniline, cyclohexylamine, octylamine, toluidine, dodecylaniline, octadecylamine, hexylamine, heptylamine, nonylamine, ethylhexylamine, decylamine, undecylamine, dodecyl Amine, tetradecylamine, pentadecylamine, nonadecylamine, eicodecylamine, oleylamine, linoleylamine, linolenylamine, methylcyclohexylamine, ethylcyclohexylamine, dimethylcyclohexylamine, diethylcyclohexylamine, butylcyclohexylamine, propylcyclohexylamine, amylcyclohexyl Amine, cyclooctylamine, benzylamine, benzhydryl Min, phenethylamine, methyl benzylamine, biphenyl amine, phenyl isopropylamine, can be suitably used phenylhexylamine like.

  Examples of the monoamine having a condensed ring hydrocarbon group as R8 or R10 include indene-based amine compounds such as aminoindene, amineindane, and amino-1-methyleneindene, aminonaphthalene (naphthylamine), aminomethylnaphthalene, aminoethylnaphthalene, Aminodimethylnaphthalene, aminocadalene, aminovinylnaphthalene, aminophenylnaphthalene, aminobenzylnaphthalene, aminodinaphthylamine, aminobinaphthyl, amino-1,2-dihydronaphthalene, amino-1,4-dihydronaphthalene, aminotetrahydronaphthalene, aminooctarine Naphthalene-based amine compounds such as aminopentalene, aminoazulene, aminoheptalene, etc., condensed bicyclic amine compounds, aminofluorene, amino-9-phenyl Aminofluorene amine compounds such as fluorene, aminoanthracene, aminomethylanthracene, aminodimethylanthracene, aminophenylanthracene, anthracene amine compounds such as amino-9,10-dihydroanthracene, aminophenanthrene, amino-1,7-dimethylphenanthrene Phenanthrene-based amine compounds such as aminoretene, aminobiphenylene, amino-s-indacene, amino-as-indacene, aminoacenaphthylene, aminoacenaphthene, amiophenalene and other condensed tricyclic amine compounds, aminonaphthacene, aminochrysene, Aminopyrene, aminotriphenylene, aminobenzoanthracene, aminoaceanthrylene, aminoaceanthrene, aminoacephenanthrylene, aminoacephe Condensed tetracyclic amine compounds such as enthrene, aminofluoranthene, aminopreaden, condensed pentacyclic amine compounds such as aminopentacene, aminopentaphene, aminopicene, aminoperylene, aminodibenzoanthracene, aminobenzopyrene, aminocholanthrene, Examples thereof include condensed polycyclic (six or more rings) amine compounds such as aminocoronene, aminopyrantolen, aminoviolanthrene, aminoisoviolanthrene and aminoovalene.

  The diurea compound represented by the formula (IV) may be used alone or in combination, and is blended in an amount of 5 to 35% by mass based on the total amount of the grease composition. When the blending amount is less than 5% by mass, it is difficult to maintain the grease state, and when it exceeds 35% by mass, the grease is hardened and a sufficient lubricating effect cannot be exhibited. In consideration of the ability to withstand higher temperatures, higher speeds, higher loads, and higher vibration conditions, the blending amount is preferably set to 10 to 30% by mass in consideration of softening of grease due to higher temperatures and higher shear and a lubricating effect.

  The blending degree of the grease composition is preferably 220 to 340. In order to obtain such a blending degree with the blending amount of the diurea compound represented by the above formula (IV), in the diurea compound represented by the formula (IV), The molar ratio of the alicyclic hydrocarbon group or the aliphatic hydrocarbon group is 100 mol, and the total amount of the alicyclic hydrocarbon group or the aliphatic hydrocarbon group is 20 mol% or more of the total amount combined with the aliphatic hydrocarbon group or the aliphatic hydrocarbon group and the aromatic hydrocarbon group. It is desirable to do.

[Conductive powder]
In order to remove the potential difference between the inner and outer rings of the bearing and prevent the peeling phenomenon, it is preferable to add conductive powder. The conductive powder is not particularly limited, but carbon powder such as carbon black or carbon nanotube can be suitably used in consideration of maintaining conductivity up to a high temperature and not deteriorating the lubricity of grease. Carbon black preferably has an average particle size of 5 μm or less, and more preferably 2 μm or less. Most preferably, an average particle diameter of 10 to 300 nm is used. Such carbon black is also available from the market, and examples thereof include Ketjen Black EC and Ketjen Black EC600JD manufactured by Lion Akzo. Carbon nanotubes having a diameter of 15 nm or less and a length of 5 μm or less, including C60 and C70 fullerenes, can be suitably used. Preferably, those having a diameter of 10 nm or less and a length of 2 μm or less are used. Such carbon nanotubes can also be obtained from the market, and examples thereof include carbon nanofiber VGCF manufactured by Showa Denko KK.

  The amount of the conductive powder added to the grease composition is preferably 0.5 to 5% by mass of the total amount of the grease composition. If the addition amount is 0.5% by mass or less, the addition effect cannot be obtained, and if it exceeds 5% by mass, the fluidity of the grease is affected. Further, if the average particle diameter or length exceeds 2 μm, the acoustic performance of the bearing may be affected.

[Rust preventive]
Since a bearing for automobile electrical equipment, which is an application of the present invention, requires high rust prevention, it is preferable to add a rust inhibitor. Among the rust preventives, rust preventives composed of carboxylic acids and carboxylates with little environmental burden, ester rust preventives, and amine rust preventives are preferable. These are used in a mixture of two or more in order to exhibit sufficient rust prevention performance, and the total content of the grease composition is 0.2 to 10% by mass, and individual rust prevention An agent is 0.1-9.9 mass%. Since seizure resistance improves as the amount of base oil increases, the rust preventive agent is preferably 0.2 to 6% by mass in total, and 0.1 to 5.9% by mass alone.

Although there is no restriction | limiting in the rust preventive agent which consists of carboxylic acid and carboxylate, an ester type rust preventive agent, and an amine type rust preventive agent, A preferable example is shown below. As carboxylic acid and carboxylate, monocarboxylic acid such as stearic acid, dicarboxylic acid such as alkyl or alkenyl succinic acid and its derivatives, naphthenic acid, abietic acid, lanolin fatty acid or calcium of alkenyl succinic acid, barium, magnesium, aluminum, Examples of the metal salt include zinc and lead. Among them, alkenyl succinic acid and zinc naphthenate are preferable. Examples of ester-based rust preventives include carboxylic acid partial esters of polyhydric alcohols such as sorbitan monooleate, sorbitan trioleate, pentaerythritol monooleate and succinic acid half ester, among others sorbitan monooleate and succinic acid. Acid half esters are preferred. As the amine-based rust inhibitor, alkoxyphenylamine, a partial amide of dibasic carboxylic acid, and the like are suitable.

[Other additives]
In order to further improve the performance of the grease composition, other additives can be further contained as necessary. Other additives include amines, phenols, sulfurs, zinc dithiophosphates, zinc dithiocarbamates, etc., extreme pressure agents such as phosphorus, zinc dithiophosphates, organic molybdenums, fatty acids, animal and vegetable oils, etc. Examples thereof include oiliness improvers, benzotriazole metal deactivators, and the like, which can be added alone or in combination of two or more. The addition amount of these additives is not particularly limited as long as the intended purpose of the present invention can be achieved, and is appropriately set.

(Rolling bearing)
The present invention also relates to a rolling bearing in which the above grease composition is enclosed. Although there is no restriction | limiting in the kind of rolling bearing, a structure, and a structure, For example, the double row angular contact ball bearing 10 shown in FIG. 1 can be illustrated. The illustrated double-row angular ball bearing 10 includes a double-row outer ring raceway 17, 17 provided on the inner peripheral surface of the outer ring 15 and an inner ring raceway 18, 18 provided on each outer peripheral surface of the inner ring 16, 16. A plurality of rolling elements (balls) 19, 19 are provided so as to be able to roll by a plurality, so that relative rotation between the outer ring 15 and the inner rings 16, 16 can be performed freely. The outer ring 15 and the inner rings 18, 18 are sealed with the sealing device 1. The sealing device 1 is formed by integrally molding a metal slinger 2 and a sealing material 3 made of an elastic material. The slinger 2 includes an outer diameter side cylindrical portion 5 that can be fitted and fixed to the inner peripheral surface of the end portion of the outer ring 15, and an inner ring portion 6 that is bent radially inward from the axial inner end edge of the outer diameter side cylindrical portion 5. A first member having an approximately L-shaped cross section and having an annular shape as a whole, an inner diameter side cylindrical portion 8 that can be fitted and fixed to the outer peripheral surface of the outer end of the inner ring 16, and an axis of the inner diameter side cylindrical portion 8 A second member having an L-shaped cross section and an annular shape as a whole, including an outer annular portion 9 bent outward in the diameter direction from the outer edge in the direction. The seal material 3 includes three seal lips 3 a, 3 b, and 3 c on the outer side, the middle side, and the inner side, and the tip end edge of the outer seal lip 3 a located on the outermost side is the outer ring portion 9 that constitutes the slinger 2. The inner edges of the intermediate seal lip 3b and the inner seal lip 3c, which are the remaining two seal lips, are slidably brought into contact with the inner surface over the entire periphery, and the outer peripheral surface of the inner diameter side cylindrical portion 8 constituting the slinger 2 Slidably in contact with each other to achieve high sealing performance.

  The grease composition is enclosed in a space formed by the outer ring 15, the inner rings 16, 16, the balls 19 and the sealing device 1. Although there is no restriction | limiting in the amount of enclosure, It is preferable to occupy 25-45 volume% of the said space.

  The rolling bearing of the present invention is filled with the above grease composition, so it operates well under conditions of high temperature, high speed, high load, and severe vibration, and also generates abnormal noise even at an extremely low temperature of -40 ° C. Therefore, it is suitable for use as an automotive electrical accessory.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is further demonstrated, this invention is not restrict | limited at all by this.

[Examples 1-8, Comparative Examples 1-2]
(Preparation of test grease)
Test greases were prepared with the formulations shown in Table 1. At that time, half of the base oil was placed in the first container, and cyclohexylamine was added and dissolved therein. In addition, half of the base oil was placed in the second container, and diphenylmethane-4,4-diisocyanate was added and dissolved therein. Then, the contents of the first container were added to the second container, and the mixture was stirred and reacted while being heated to about 70 ° C. Thereafter, the temperature was raised to 160 ° C. to finish the reaction, and after cooling, a rust inhibitor and an antioxidant were added, passed through a roll mill, and defoamed to obtain a test grease. The total amount of the rust inhibitor was 2% by mass, and the kind and the amount of the antioxidant were common.

  Using the test grease prepared as described above, the following (1) seizure test-I, (2) low-temperature abnormal noise test-I, (3) high-temperature consistency change test, and (4) rust prevention test were performed. . The results are also shown in Table 1.

(1) Seizure test-I
A test bearing was prepared by enclosing 1 g of test grease in a double row angular contact ball bearing (see FIG. 1) with a contact rubber seal having an inner diameter of 35 mm, an outer diameter of 52 mm, and a width of 20 mm. Then, it was continuously rotated under the conditions of an outer ring rotational speed of 10000 min ⁻¹ , a bearing temperature of 170 ° C., and a radial load of 1960 N, and when the bearing outer ring temperature rose by 15 ° C., it was regarded as seizure, and the test was completed. The results are shown as relative values with the seizure life of Comparative Example 3 as 1.

(2) Low temperature abnormal noise test-I
A test bearing was prepared by enclosing 3.5 g of test grease in a single row deep groove ball bearing with a contact rubber seal having an inner diameter of φ25 mm, an outer diameter of φ62 mm, and a width of 17 mm. Then performed -30 ° C., the operation of rotating at 3600 min ^-1 5 seconds after rotating 5 seconds inner ring at a rotation speed 1800 min ^-1 under the conditions of axial load 980 N 5 times repeated, confirming the presence or absence of the occurrence of abnormal noise did. The case where abnormal noise was generated was regarded as rejected.

(3) High-temperature consistency change test The test grease was applied in a 3 mm thick film on an iron plate and allowed to stand in a 170 ° C environment for 240 hours. The mixture penetration was measured after standing and compared with the blend penetration before standing. The case where the change of the penetration degree exceeded ± 100 was regarded as unacceptable.

(4) Rust prevention test 2.7 g of test grease is sealed in a single row deep groove ball bearing having an inner diameter of 17 mm, an outer diameter of 47 mm, and a width of 14 mm, and 0.3 mL of 0.1% sodium chloride aqueous solution is injected into the bearing. A test bearing was prepared with a non-contact seal attached. The test bearing was rotated to spread the test grease and sodium chloride aqueous solution inside the bearing, and then left in an environment of 60 ° C. and 70% RH for 3 days. After leaving, the test bearing was disassembled, and the inner ring raceway surface was observed to confirm the presence or absence of rust. The case where rust was generated was regarded as rejected.

  As shown in Table 1, according to the present invention, the test greases of the examples containing the base oil containing the aromatic ester oil and the diurea compound represented by the general formula (IV) as the thickener were mixed at a high temperature. There is little change in consistency and excellent high-temperature durability. Further, by enclosing the test grease of the example, it is possible to improve the seizure life of the bearing, to suppress the generation of abnormal noise at a low temperature, and to improve rust prevention. However, as in Example 8, even when a base oil containing an aromatic ester oil is used and a diurea compound having an aliphatic hydrocarbon group is used as a thickener, if the base oil viscosity is high, abnormal noise is generated at a low temperature. To occur. Moreover, even if it uses the base oil containing an aromatic ester oil like the comparative example 1, when it uses the triurea compound which has an aromatic hydrocarbon group for a thickener, it will become inferior to high temperature durability, and also rust prevention Since the agent is succinic acid half ester alone, the rust prevention performance is also lowered.

(Verification of Aromatic Ester Oil Content-I)
A test grease was prepared using a base oil in which the blending ratio of trimellitic acid ester oil and pentaerythritol ester oil was changed according to the blending of the test grease of Example 7. And said (1) image sticking test-I was done using the test grease.

  FIG. 2 is a graph showing the relationship between the content of trimellitic ester oil and the seizure life. The seizure life is shown as a relative value with respect to the case of pentaerythritol ester oil alone (100%). As shown in the figure, it is found that the seizure life is particularly improved by containing 30% by mass or more of trimellitic acid ester oil.

(Verification of thickener blending amount-I)
According to the formulation of the test grease of Example 5, test greases were prepared by changing the blending amount of the thickener. And said (1) image sticking test-I was done using the test grease.

  FIG. 3 is a graph showing the relationship between the blending amount of the thickener and the seizure life. The seizure life is shown as a relative value with respect to Comparative Example 3. As shown in the figure, it can be seen that the seizure life is improved by blending the thickener in an amount of 5 to 35 mass%, particularly 10 to 30 mass%.

(Relationship between pour point of base oil and generation of low-temperature abnormal noise -I)
Base oils with different pour points are prepared using a pentaerythritol ester having a pour point of −55 ° C. and a pyromellitic acid ester having a pour point of −20 ° C., and each base oil is blended with a diurea compound having an alicyclic hydrocarbon group. A test grease was prepared. The blending amount of the diurea compound is constant and the blending consistency No. Adjusted to 2. And said (2) low temperature abnormal noise test-I was done using test grease.

  FIG. 4 shows the relationship between the pour point of the base oil and the generation of abnormal noise. It can be seen that no abnormal noise is generated when the pour point of the base oil is −30 ° C. or lower.

[Examples 9-15, Comparative Examples 3-5]
(Preparation of test grease)
Test greases were prepared with the formulations shown in Table 2. At that time, half of the base oil was placed in the first container, and cyclohexylamine was added and dissolved therein. In addition, half of the base oil was placed in the second container, and diphenylmethane-4,4-diisocyanate was added and dissolved therein. Then, the contents of the first container were added to the second container, and the mixture was stirred and reacted while being heated to about 70 ° C. Thereafter, the temperature was raised to 160 ° C. to complete the reaction, and after cooling, a rust inhibitor, an antioxidant and carbon black were added, passed through a roll mill, and defoamed to obtain a test grease. In addition, the kind and compounding quantity of antioxidant were made common.

  Using the test grease prepared as described above, the following (1) seizure test-II, (2) low-temperature abnormal noise test-II, and (5) peeling resistance test were performed. Moreover, the same (3) high-temperature consistency change test and (4) rust prevention test were performed as described above. The results are also shown in Table 2.

(1) Seizure test-II
A test bearing was prepared by enclosing 1 g of test grease in a double row angular contact ball bearing (see FIG. 1) with a contact rubber seal having an inner diameter of 35 mm, an outer diameter of 52 mm, and a width of 20 mm. Then, it was continuously rotated under the conditions of an outer ring rotational speed of 13000 min ⁻¹ , a bearing temperature of 130 ° C., and a radial load of 1560 N, and when the bearing outer ring temperature rose by 15 ° C., it was regarded as seizure, and the test was completed. The time taken until seizure was set as 1000 hours or more.

(2) Low-temperature abnormal noise test-II
A test bearing was prepared by enclosing 3.5 g of test grease in a single row deep groove ball bearing with a contact rubber seal having an inner diameter of φ25 mm, an outer diameter of φ62 mm, and a width of 17 mm. Then, the inner ring was rotated at 2600 min ⁻¹ for 30 seconds under the conditions of −30 ° C. and an axial load of 9800 N, and the presence or absence of abnormal noise was confirmed. The case where abnormal noise was generated was regarded as rejected.

(5) Peel resistance test A single-row deep groove ball bearing with an inner diameter of φ17 mm, outer diameter of φ47 mm, and width of 14 mm is filled with 2.5 g of test grease to form a test bearing. This test bearing is incorporated into the alternator of the actual engine and is at room temperature When the engine is repeatedly rotated continuously at 1000 to 6000 min ⁻¹ (bearing speed 2400 to 13300 min ⁻¹ ) with a pulley load of 1560 N, the vibration value at that time is measured, and the vibration value exceeds 5 times the initial value It was assumed that peeling occurred. The test was performed 10 times, and the number of times of peeling was determined in less than 500 hours of rotation.

  As shown in Table 2, according to the present invention, the test grease of the example containing the base oil containing the aromatic ester oil and the diurea compound represented by the general formula (IV) as the thickener was mixed at high temperature. There is little change in consistency and excellent high-temperature durability. In addition, by enclosing the test grease of the example, it is possible to improve the seizure life of the bearing, to suppress the generation of abnormal noise at a low temperature, and to improve rust prevention. Furthermore, peeling resistance improves also by containing electroconductive powder. On the other hand, as in Comparative Example 3, a test grease containing an excessive amount of conductive powder adversely affects the acoustic characteristics, and abnormal noise is generated at a low temperature. Further, as in Comparative Example 4, even when a base oil containing an aromatic ester oil is used, if a triurea compound having an aromatic hydrocarbon group is used as a thickener, the high temperature durability becomes inferior, and further rust prevention is achieved. Since the agent is succinic acid half ester alone, the rust prevention performance is also lowered. Moreover, in Comparative Example 4 and Comparative Example 5, since the conductive powder is not contained, the peel resistance is also inferior.

(Verification of aromatic ester oil content-II)
A test grease was prepared using a base oil in which the blending ratio of trimellitic ester oil and poly α-olefin oil was changed in accordance with the blending of the test grease of Example 15. And said (1) image sticking test-II was done using test grease.

  FIG. 5 is a graph showing the relationship between the content of trimellitic ester oil and the seizure life. The seizure life is shown as a relative value relative to the case of poly α-olefin oil alone (100%). As shown in the figure, it is found that the seizure life is particularly improved by containing 30% by mass or more of trimellitic acid ester oil.

(Verification of thickener blending amount-II)
According to the blending of the test grease of Example 11, test greases were prepared by changing the blending amount of the thickener. And said (1) image sticking test-II was done using test grease.

  FIG. 6 is a graph showing the relationship between the blending amount of the thickener and the seizure life. The seizure life is shown as a relative value with respect to Comparative Example 5. As shown in the figure, it can be seen that the seizure life is improved by blending the thickener in an amount of 5 to 35 mass%, particularly 10 to 30 mass%.

(Relationship between pour point of base oil and generation of low-temperature noise-II)
Base oils with different pour points are prepared using a pentaerythritol ester having a pour point of −55 ° C. and a pyromellitic acid ester having a pour point of −20 ° C., and each base oil is blended with a diurea compound having an alicyclic hydrocarbon group. A test grease was prepared. The blending amount of the diurea compound is constant and the blending consistency No. Adjusted to 2. And said (2) low temperature abnormal noise test-II was done using test grease.

  FIG. 7 shows the relationship between the pour point of the base oil and the generation of abnormal noise. It can be seen that no abnormal noise is generated when the pour point of the base oil is −30 ° C. or lower.

(Verification of carbon black content)
Test greases were prepared by changing the amount of carbon black added according to the formulation of the test grease of Example 9. And said (5) peeling resistance test was done using the test grease, and the peeling occurrence probability was calculated by the following formula.
Peeling occurrence probability (%) = [number of peeling occurrence / number of tests (= 10)] × 100

  FIG. 8 shows the relationship between the amount of carbon black added and the probability of delamination. It can be seen that the delamination can be suppressed by adding 0.5% by mass or more of carbon black.

(Verification of carbon black particle size)
In accordance with the formulation of the test grease of Example 9, carbon black having a particle size of 34 nm to 6 μm was added (however, the amount added was constant at 5 mass%) to prepare a test grease. Then, the test grease was sealed in a single row deep groove ball bearing having an inner diameter of 17 mm, an outer diameter of 47 mm, and a width of 14 mm so as to occupy 35% of the space volume to produce a test bearing. The test bearing was rotated at an inner ring rotational speed of 1800 min ⁻¹ with an axial load of 49 N in a room temperature atmosphere, and an Anderon value (1800 to 10000 Hz) was measured for 120 seconds from the start of rotation. If the Anderon value during this period is 2.5 or less, it is practically acceptable.

  FIG. 9 shows the relationship between the particle size of the carbon black and the Anderon value. It can be seen that by using carbon black having a particle size of 5 μm or less, it is possible to impart peeling resistance while maintaining acoustic characteristics.

It is sectional drawing which shows the double row angular contact ball bearing which is one Embodiment of the rolling bearing of this invention. It is a graph which shows the result of verification-I of content of aromatic ester oil. It is a graph which shows the result of verification -I of a thickener compounding quantity. It is a graph which shows the relationship -I of the pour point of base oil, and low temperature abnormal noise generation | occurrence | production. It is a graph which shows the result of verification-II of content of aromatic ester oil. It is a graph which shows the result of verification -II of a thickener compounding quantity. It is a graph which shows the relationship of the pour point of base oil, and low temperature abnormal noise generation | occurrence | production-II. It is a graph which shows the relationship between carbon black addition amount and a peeling generation | occurrence | production probability. It is a fluff showing the relationship between the carbon black particle diameter and the Anderon value.

Explanation of symbols

10 Double-row angular contact ball bearing 15 Outer ring 16 Inner ring 17 Outer ring raceway 18 Inner ring raceway 19 Rolling element (ball)

Claims (7)

A base oil containing 30% by mass or more of an aromatic ester oil based on the total amount of the base oil, and a diurea compound represented by the following general formula as a thickener is contained in an amount of 5 to 35% by mass based on the total amount of the grease composition. A grease composition for automotive electrical equipment.
R8-NHCONH-R9-NHCONH-R10
(In the formula, R9 is an aromatic hydrocarbon group having 6 to 15 carbon atoms, and R8 and R10 are an aliphatic hydrocarbon group, an alicyclic hydrocarbon group or a condensed ring, which may be the same as or different from each other. .)   2. The grease composition for automotive electrical equipment according to claim 1, wherein the aromatic ester oil is at least one of trimellitic acid ester oil and pyromellitic acid ester oil.   The grease composition for automotive electrical equipment according to claim 2, wherein the derived hydrocarbon group in trimellitic acid ester oil and pyromellitic acid ester oil is a hydrocarbon group having 6 to 10 carbon atoms.   The grease composition for automotive electrical equipment according to any one of claims 1 to 3, wherein the conductive powder contains at least one of carbon black and carbon nanotubes.   A total of two or more selected from a rust inhibitor made of carboxylic acid or a carboxylate salt, an ester rust inhibitor, and an amine rust inhibitor, based on the total amount of the grease composition, and alone It contains in 0.1-9.9 mass% in any one of Claims 1-4, The grease composition for motor vehicle auxiliary equipment of any one of Claims 1-4 characterized by the above-mentioned.   A plurality of rolling elements are rotatably held by a cage between the inner ring and the outer ring, and the grease composition for automotive electrical equipment according to any one of claims 1 to 5 is enclosed. Characteristic rolling bearing.   7. A rolling bearing according to claim 6, further comprising a contact type rubber seal.

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