Grease composition and constant velocity joint encapsulating the same

Abstract

To provide a grease composition having excellent seizure resistance.SOLUTION: A grease composition comprises (a) a diurea-based thickener, (b) a base oil, (c) an overbased calcium sulfonate, and (d) disodium sebacate, wherein a content of the component (c) is 1.5 to 3.5 mass% based on a total mass of the composition, and a content of the component (d) is 0.2 to 1 mass% based on the total mass of the composition.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a grease composition that can be suitably used for constant velocity joints, particularly for outboard constant velocity joints. [Background technology]

[0002] As part of efforts to reduce CO2 emissions and contribute to the environment, front-wheel drive (FF) vehicles are becoming increasingly popular due to their lightweight design and increased interior space. Constant velocity joints (hereafter sometimes referred to as "CVJs") are widely used in FF vehicles to transmit the torque from the engine, motor, and other powertrain units to the tires. In recent years, with the promotion of a decarbonized society, the automotive industry has been working to reduce CO2 emissions and improve fuel efficiency and power consumption. These efforts have necessitated the ability to accommodate high load capacity through compact and lightweight vehicles. Because CVJs rotate at an angle, the components inside the joint undergo complex rolling and sliding motions. The outboard CVJ, in particular, has a large steering angle, which increases the rolling and sliding distance within the CVJ and significantly increases the maximum load per ball. Furthermore, as CVJs become smaller and lighter, all of the components within the CVJ become smaller, requiring grease with even higher load-bearing capacity. Insufficient load-bearing capacity can lead to flaking due to minute seizures caused by metal contact, resulting in noise and other problems. While structural improvements to the CVJ itself have been made to address these issues, cost remains a significant challenge, creating a demand for greases with higher load-bearing capacity. Therefore, greases containing additives with high load-bearing capacity are needed for smaller, higher-capacity CVJs. Various grease compositions have been proposed as greases capable of preventing the occurrence of flaking in CVJs. For example, Patent Document 1 proposes a grease composition containing a base oil, a urea-based thickener, molybdenum disulfide, and a specific calcium salt. Patent Document 2 proposes a grease composition for constant velocity joints containing a base oil, a urea-based thickener, molybdenum disulfide, a specific calcium salt, a metal-free sulfur-phosphorus-based extreme pressure agent, and molybdenum dithiocarbamate. Patent Document 3 proposes a grease composition for constant velocity joints containing a base oil selected from the group consisting of mineral oil, ether-based synthetic oil, ester-based synthetic oil, hydrocarbon-based synthetic oil, and a mixture of two or more of these oils, and a diurea-based thickener represented by the following formula: R 4 -NH-CO-NH-C6H4-p-CH2-C6H4-p-NH-CO-NHR 5 (R 4 and R 5 is an alkyl group having 8 carbon atoms), molybdenum disulfide, molybdenum sulfide dialkyldithiocarbamate represented by the following formula, (R 6 R 7 N-CS-S)2-Mo2OmSn (In the formula, R 6 , R 7 each independently represents an alkyl group having 1 to 24 carbon atoms, m is 0 to 3, n is 4 to 1, and m+n=4. A composition for constant velocity joints has been proposed, which contains at least one calcium salt selected from the group consisting of calcium salts of petroleum sulfonic acids and overbased calcium salts of petroleum sulfonic acids, 1.5 to 10 mass% of a sulfur-phosphorus extreme pressure agent based on the composition, and vegetable oil. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-194871 [Patent Document 2] Japanese Patent Application Publication No. 9-324189 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-96949 Summary of the Invention [Problem to be solved by the invention]

[0004] Thus, the flaking resistance life of grease compositions for CVJs to date has been investigated using bench tests and SRV tests under low loads. However, it cannot be said that sufficient research has been conducted into the anti-seizure properties that can withstand the extremely high loads that accompany the trend toward smaller, higher-capacity engines. Therefore, an object of the present invention is to provide a grease composition that has excellent anti-seizure properties, taking into consideration the trend toward smaller and higher-capacity CVJs. [Means for solving the problem]

[0005] According to the present invention, the following grease is provided. 1.(a) Diurea-based thickeners, (b) base oil; (c) 0.1 to 10% by weight, based on the total weight of the composition, of an overbased calcium sulfonate, and (d) 0.01 to 5% by mass of disodium sebacate, based on the total mass of the composition; A grease composition comprising: 2. The grease composition according to 1 above, wherein the base number of component (c) is 200 to 500 mgKOH / g. 3. The grease composition according to 1 or 2 above, wherein component (a) is a diurea compound represented by the following formula (1): R 1 -NHCONH-R 2 -NHCONH-R 3 (1) (In the formula, R 1 and R 3 may be the same or different and are an alkyl group having 8 to 18 carbon atoms, an aryl group having 6 carbon atoms, or a cyclohexyl group. 2 is a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms. 4. The grease composition according to any one of 1 to 3 above, further comprising at least one member selected from the group consisting of component (e-1) oil-insoluble molybdenum dialkyldithiocarbamate (MoDTC) and component (e-2) oil-soluble molybdenum dialkyldithiocarbamate (MoDTC). 5. The grease composition according to 4 above, containing component (e-1) and component (e-2). 6. The grease composition according to any one of 1 to 5 above, which does not contain a neutral zinc sulfonate. 7. The grease composition according to any one of 1 to 6 above, which is for use in a constant velocity joint. 8. The grease composition according to any one of 1 to 7 above, which is for use in an outboard constant velocity joint. 9. A constant velocity joint filled with the grease composition according to any one of 1 to 8 above. [Effects of the Invention]

[0006] The present invention provides a grease composition with extremely high seizure resistance. Without being bound by any theory, it is believed that the grease composition of the present invention forms a strong additive film, preventing contact between metal base materials, and is also capable of quickly forming a dense oxide film even if metal contact occurs and a new surface is created due to wear. DETAILED DESCRIPTION OF THE INVENTION

[0007] (a) Diurea-based thickener The thickener of the present invention is a diurea-based thickener, which is easily softened quickly by shearing, allowing the grease to be supplied sufficiently to the sliding parts within the CVJ. The thickener of the present invention is preferably a diurea compound represented by the following formula (1). R 1 -NHCONH-R 2 -NHCONH-R 3 (1) (In the formula, R 1 and R 3may be the same or different and are an alkyl group having 8 to 18 carbon atoms, an aryl group having 6 carbon atoms, or a cyclohexyl group. 2 is a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms. The diurea compound is obtained by reacting a diisocyanate component with a monoamine component. Examples of diisocyanates include diphenylmethane diisocyanate, octadecane diisocyanate, decane diisocyanate, hexane diisocyanate, toluene diisocyanate, etc. Examples of monoamines include octylamine, dodecylamine, hexadecylamine, stearylamine, oleylamine, aniline, p-toluidine, cyclohexylamine, etc., and mixtures thereof.

[0008] Of the diurea compounds represented by formula (1), a diurea compound selected from the group consisting of an aliphatic diurea compound, an aromatic diurea compound, an alicyclic diurea compound, an alicyclic aromatic diurea compound, and an alicyclic aliphatic diurea compound is preferably used as the diurea-based thickener of the present invention. Among these, the alicyclic aromatic diurea compound uses a mixture of cyclohexylamine and an aromatic amine as the raw amine, and therefore the diurea compound obtained by the reaction is a mixture of an alicyclic diurea compound, an aromatic diurea compound, and an alicyclic aromatic diurea compound. In other words, the alicyclic aromatic diurea compound is a mixture of diurea compounds represented by the following formulas (1-1), (1-2), and (1-3). R 1 -NHCONH-R 2 -NHCONH-R 1 (1-1) R 1 -NHCONH-R 2 -NHCONH-R 3 (1-2) R 3 -NHCONH-R 2 -NHCONH-R 3 (1-3) In the formula, R 1 is a cyclohexyl group, and R 3is an aryl group having 6 carbon atoms, and R 2 is as defined above. R 1 and R 3 The molar ratio of R 1 :R 3 The ratio is preferably 60:40 to 80:20, and more preferably 65:35 to 75:25.

[0009] Similarly, since a mixture of cyclohexylamine and an aliphatic amine is used as the raw amine for the alicyclic aliphatic diurea compound, the diurea compound obtained by the reaction is a mixture of an alicyclic diurea compound, an aliphatic diurea compound, and an alicyclic aliphatic diurea compound. In other words, the alicyclic aliphatic diurea compound is a mixture of diurea compounds represented by the following formulas (1-1), (1-2), and (1-3). R 1 -NHCONH-R 2 -NHCONH-R 1 (1-1) R 1 -NHCONH-R 2 -NHCONH-R 3 (1-2) R 3 -NHCONH-R 2 -NHCONH-R 3 (1-3) In the formula, R 1 is a cyclohexyl group, and R 3 is an alkyl group having 8 to 18 carbon atoms, and R 2 is as defined above. R 1 and R 3 The molar ratio of R 1 :R 3 The ratio is preferably 70:30 to 95:5, and more preferably 75:25 to 93:7.

[0010] When two alkylamines are used as raw amines, the diurea compounds obtained by the reaction are also a mixture, that is, a mixture of diurea compounds represented by the following formulas (1-1), (1-2), and (1-3). R 1 -NHCONH-R 2-NHCONH-R 1 (1-1) R 1 -NHCONH-R 2 -NHCONH-R 3 (1-2) R 3 -NHCONH-R 2 -NHCONH-R 3 (1-3) In the formula, R 1 is an alkyl group having 8 to 18 carbon atoms, and R 3 is another alkyl group having 8 to 18 carbon atoms, and R 2 is as defined above. R 1 and R 3 The molar ratio of R 1 :R 3 The ratio is preferably 70:30 to 30:70, and more preferably 60:40 to 40:60.

[0011] As the thickener of the present invention, alicyclic aromatic diurea compounds, alicyclic aliphatic diurea compounds, and aliphatic diurea compounds are more preferred. especially, In formulas (1-1) and (1-2), R 1 is a cyclohexyl group, and in formulas (1-2) and (1-3), R 3 is an alicyclic aromatic diurea compound in which In formulas (1-1) and (1-2), R 1 is a cyclohexyl group, and in formulas (1-2) and (1-3), R 3 is a phenyl group, and R 1 :R 3 = 7:3 (molar ratio), or In formulas (1-1) and (1-2), R 1 is a cyclohexyl group, and in formulas (1-2) and (1-3), R 3 is an alicyclic aliphatic diurea compound in which In formulas (1-1) and (1-2), R 1 is a cyclohexyl group, and in formulas (1-2) and (1-3), R 3 is an alkyl group having 18 carbon atoms, and R1 :R 3 = 8:2 (molar ratio), or In formula (1), R 1 and R 3 are aliphatic diurea compounds in which each of them is an alkyl group having 8 carbon atoms, or In formulas (1-1) and (1-2), R 1 is an alkyl group having 8 or 18 carbon atoms, and in formulas (1-2) and (1-3), R 3 are the same or different alkyl groups having 8 or 18 carbon atoms, or In formulas (1-1) and (1-2), R 1 is an alkyl group having 8 carbon atoms, and in formulas (1-2) and (1-3), R 3 is an aliphatic diurea compound in which the alkyl group has 18 carbon atoms; or In formulas (1-1) and (1-2), R 1 is an alkyl group having 8 carbon atoms, and in formulas (1-2) and (1-3), R 3 is an alkyl group having 18 carbon atoms, and R 1 :R 3 It is preferable that the aliphatic diurea compound has a molar ratio of 5:5.

[0012] Among them, In formulas (1-1) and (1-2), R 1 is a cyclohexyl group, and in formulas (1-2) and (1-3), R 3 is a phenyl group, and R 1 :R 3 = 7:3 (molar ratio), or In formulas (1-1) and (1-2), R 1 is a cyclohexyl group, and in formulas (1-2) and (1-3), R 3 is an alkyl group having 18 carbon atoms, and R 1 :R 3 = 8:2 (molar ratio), or In formula (1), R 1 and R 3are aliphatic diurea compounds in which each of them is an alkyl group having 8 carbon atoms, or In formulas (1-1) and (1-2), R 1 is an alkyl group having 8 carbon atoms, and in formulas (1-2) and (1-3), R 3 is an alkyl group having 18 carbon atoms, and R 1 :R 3 It is preferable that the aliphatic diurea compound has a molar ratio of 5:5. In particular, In formulas (1-1) and (1-2), R 1 is a cyclohexyl group, and in formulas (1-2) and (1-3), R 3 is a phenyl group, and R 1 :R 3 An alicyclic aromatic diurea compound in which the molar ratio is 7:3 is preferred.

[0013] From the viewpoint of ease of filling the lubricated parts with the grease, the content of the diurea thickener is preferably 3 to 20 mass%, more preferably 4 to 18 mass%, and even more preferably 5 to 16 mass%, based on the total mass of the composition. By including the thickener in such a range, the hardness becomes such that the grease can easily flow within the lubricated parts (a consistency of 300 to 380), ensuring that the grease can flow into the lubricated parts immediately after the start of use. In this specification, the term "consistency" refers to the 60-stroke worked consistency measured according to JIS K 2220 7.

[0014] (b) Base oil The type of base oil used in the present invention is not particularly limited, and may be either a mineral oil or a synthetic oil. As the mineral oil, paraffinic mineral oil and naphthenic mineral oil may be used either alone or in combination. Examples of synthetic oils include synthetic hydrocarbon oils such as polyalphaolefins and polybutenes, ether-based synthetic oils such as alkyldiphenyl ethers, ester oils, silicone oils, and fluorinated oils. Synthetic oils may be so-called biomass oils, which are produced using biological resources derived from animals and plants as raw materials. For example, biomass ester oils synthesized from various fatty acids and alcohols derived from vegetable oils, and biomass hydrocarbon oils derived from vegetable oils such as palm oil, corn oil, and soybean oil can also be used. The base oil may be used alone or in combination of two or more. Among these, mineral oils are preferred from the standpoint of cost, and paraffinic mineral oils are particularly preferred because they are easily available.

[0015] The kinematic viscosity of the base oil of the present invention at 100°C is 6mm, from the viewpoint of ensuring the oil film thickness of the base oil in the lubricated parts and further preventing metal contact to improve durability. 2 / s or more is preferable, and 8 mm 2 / s or more is more preferable. The higher the kinematic viscosity at 100°C, the better, as this ensures a thick oil film of the base oil in the lubricating parts of the CVJ and prevents metal contact, improving durability. However, the viscosity at low temperatures increases, so the kinematic viscosity at 100°C should be 20mm 2 / s or less is preferable, and 16 mm 2 In this specification, the kinematic viscosity is measured in accordance with JIS K 2283. The base oil of the present invention has a kinematic viscosity at 100°C of 8 to 16 mm 2 Paraffinic mineral oils of / s are especially preferred. From the viewpoint of ease of filling the lubricated parts with the grease, the content of the base oil is preferably 60 to 95 mass%, more preferably 65 to 94 mass%, and even more preferably 70 to 92 mass% based on the total mass of the composition. By including the base oil in such a range, the consistency becomes 300 to 380, which is a hardness that makes it easy to fill the lubricated parts.

[0016] (c) Overbased calcium sulfonate Examples of the overbased calcium sulfonate used in the present invention include overbased calcium salts of alkyl aromatic sulfonic acids, overbased calcium salts of petroleum sulfonic acids, overbased calcium salts of oxidized waxes, and combinations thereof. Of these, overbased calcium salts of alkyl aromatic sulfonic acids are preferred. The overbased calcium sulfonate is not particularly limited in terms of base number, as long as it is overbased, and the base number measured in accordance with JIS K 2501 is, for example, 200 to 500 mgKOH / g, preferably 230 to 470 mgKOH / g, and more preferably 250 to 450 mgKOH / g. Note that the overbased calcium sulfonate may be used in combination with a calcium sulfonate other than the overbased calcium sulfonate (e.g., a neutral calcium sulfonate), so long as the total base number is within the above range. The content of the overbased calcium sulfonate is 0.1 to 10 mass%, preferably 0.5 to 5 mass%, and more preferably 1.5 to 3.5 mass%, based on the total mass of the composition. By including the overbased calcium sulfonate in this range, sufficient extreme pressure performance can be obtained.

[0017] (d) Disodium sebacate Disodium sebacate that can be used in the present invention can be represented by the following general formula (4). NaOOC-R 12 -COONa (4) (R in the formula 12 represents a saturated hydrocarbon group having 8 carbon atoms. Disodium sebacate may be synthesized by a known method or may be a commercially available product. The content of disodium sebacate is 0.01 to 5 mass%, more preferably 0.1 to 2 mass%, and even more preferably 0.2 to 1 mass%, based on the total mass of the composition. By including disodium sebacate in such a range, sufficient extreme pressure properties can be obtained.

[0018] In addition to the above components, the grease composition of the present invention may further contain at least one member selected from the group consisting of (e-1) oil-insoluble molybdenum dialkyldithiocarbamates (MoDTC) and (e-2) oil-soluble molybdenum dialkyldithiocarbamates (MoDTC). The oil-insoluble MoDTC is preferably one represented by the following formula (2). [R 13 2N-CS-S]2-Mo2O m1 S n1 (2) (In the formula, R 13 is a primary or secondary alkyl group having 1 to 4 carbon atoms, preferably a primary or secondary alkyl group having 2 to 4 carbon atoms, m1 is 0 to 3, n1 is 1 to 4, and m1+n1=4. The oil-soluble MoDTC is preferably one represented by the following formula (3). [R 14 2N-CS-S]2-Mo2O m2 S n2 (3) (In the formula, R 14 is a primary or secondary alkyl group having 5 to 24 carbon atoms, m2 is 0 to 3, n2 is 1 to 4, and m2+n2=4. From the viewpoint of low friction, the content of the oil-insoluble MoDTC is preferably 0.01 to 10 mass %, more preferably 0.1 to 5 mass %, and even more preferably 0.3 to 3 mass %, based on the total mass of the composition. From the viewpoint of low friction, the content of the oil-soluble MoDTC is preferably 0.01 to 10 mass %, more preferably 0.1 to 5 mass %, and even more preferably 0.5 to 3 mass %, based on the total mass of the composition.

[0019] In addition to the above components, the grease composition of the present invention may further contain additives that are commonly used in grease compositions, such as molybdenum disulfide, solid lubricants other than those described in (d) and (e-1), extreme pressure additives, antioxidants, rust inhibitors, oiliness agents, etc. Examples of solid lubricants include inorganic substances such as soil graphite, flaky graphite, carbon black, boron nitride, potassium borate, and calcium carbonate, and organic substances such as melamine cyanurate, polytetrafluoroethylene, copper salts and iron salts of dithiocarbamic acid, stearic acid, and calcium salts, aluminum salts, sodium salts, and lithium salts of sebacic acid. Examples of extreme pressure additives include phosphate esters such as triphenyl phosphate, triphenylthiophosphate, triaryl phosphate, tricresyl phosphate, zinc dialkyldithiophosphate, and other organic acid salts such as zinc salts and copper salts of naphthenic acid and zinc salts of dithiocarbamic acid, azole compounds such as benzotriazole and dialkylmercaptothiadiazole, fatty acids obtained by decomposing and modifying fats and oils obtained from animals and plants, mono- and diglycerides, polyhydric alcohols such as glycerin, alkyd resins, hardened oils, chlorinated fats and oils, sulfurized fats and oils, and sulfurized esters. Examples of antioxidants include amine-based and phenol-based antioxidants. Examples of the rust inhibitor include sulfonates such as sodium sulfonate and lithium sulfonate, carboxylic acids such as succinic acid, half esters and diesters of succinic acid, and amines such as diphenylamine compounds. Examples of oily agents include fats and oils obtained from animals and plants, such as beef tallow, lard, fish oil, castor oil, palm oil, soybean oil, and rapeseed oil; esters such as trimethylolpropane oleate ester, pentaerythritol stearate ester, dioctyl sebacate, dioctyl adipate, dioctyl phthalate, and dibutyl phthalate; higher alcohols such as cetyl alcohol, stearyl alcohol, and oleyl alcohol; glycerin; and glycerides obtained by reacting glycerin with alcohol. Preferably, the optional additive does not include neutral zinc sulfonate. The content of such optional additives is, for example, 0.01 to 10 mass %, preferably 0.1 to 5 mass %, based on the total mass of the composition.

[0020] The grease composition of the present invention is preferably used in constant velocity joints, and more preferably in outboard constant velocity joints. The lubrication pattern of outboard joints is point contact, where the balls come into contact with the rolling surfaces of the inner and outer rings, and requires higher extreme pressure resistance than the lubrication pattern of inboard joints, which is mainly line contact. Constant velocity joints are made of metal.

[0021] The grease composition of the present invention includes: (a) Diurea-based thickeners, in the formulas (1-1) and (1-2), R 1 is a cyclohexyl group, and in formulas (1-2) and (1-3), R 3 is a phenyl group, and R 1 :R 3 an alicyclic aromatic diurea compound having a molar ratio of 1:2; (b) As a base oil, a kinematic viscosity at 100°C of 8 to 16 mm 2 / s paraffinic mineral oil, (c) 1.5 to 3.5% by weight, based on the total weight of the composition, of an overbased calcium sulfonate having an acidity of 250 to 450 mg KOH / g; (d) disodium sebacate in an amount of 0.2 to 1% by mass based on the total mass of the composition; A grease composition comprising: is particularly preferred. It is preferable that the grease composition further contains (e-1) an oil-insoluble MoDTC in an amount of 0.3 to 3 mass % based on the total mass of the composition, and (e-2) an oil-soluble MoDTC in an amount of 0.5 to 3 mass % based on the total mass of the composition. It is particularly preferred that any of the above grease compositions be used for constant velocity joints, and even more particularly preferred that any of the above grease compositions be used for outboard constant velocity joints. [Example]

[0022] The following components were used to prepare the grease compositions of the Examples and Comparative Examples. <Thickener> (a) Thickener Alicyclic aromatic diurea: reaction product of 1 mole of 4,4'-diphenylmethane diisocyanate and 2 moles of raw amine (cyclohexylamine:aniline = 7:3 (molar ratio)) Aliphatic diurea A: reaction product of 1 mole of 4,4'-diphenylmethane diisocyanate with 2 moles of raw amine (octylamine:octadecylamine = 5:5 (molar ratio)) Aliphatic diurea B: reaction product of 1 mole of 4,4'-diphenylmethane diisocyanate with 2 moles of raw amine (octylamine) Alicyclic aliphatic diurea: reaction product of 1 mole of 4,4'-diphenylmethane diisocyanate with 2 moles of raw amine (cyclohexylamine:stearylamine = 8:2 (molar ratio))

[0023] <Base oil> (b) Paraffinic mineral oil (500 neutral oil, kinematic viscosity at 100°C = 11 mm 2 / s) <Additives> (c) Calcium sulfonate (overbased): calcium salt of alkyl aromatic sulfonic acid (LUBRIZOL 5283C, manufactured by The Lubrizol Corporation, base number 350-400 mg KOH / g) (d) Sebacic acid sodium salt (e-1) MoDTC (oil-insoluble): molybdenum dithiocarbamate (ADEKA Sakuralube 600, manufactured by ADEKA) (e-2) MoDTC (oil-soluble): Molybdenum dithiocarbamate (ADEKA Sakuralube 525, manufactured by ADEKA) (f) Ca sulfonate (neutral): calcium salt of alkyl aromatic sulfonic acid (Alox2292B, manufactured by LUBLIZOL, base number 0 to 10 mg KOH / g) (g) Zn sulfonate (neutral): zinc salt of alkyl aromatic sulfonic acid (Na-sul Zs, manufactured by KING, base value 0-10 mg KOH / g)

[0024] <Preparation of grease composition> In the base oil, the raw material of the thickener was reacted, the temperature was raised, and after cooling, it was milled with a three-roll mill to obtain a base grease. An additive was added to the base grease to obtain the grease compositions of the examples and comparative examples.

[0025] <Test method> <Consistency> The consistency was unified to the NLGI No.1 grade (310 - 340). The consistency was measured according to JISK2220. <SRV test> · SRV test under high load According to the method specified in ASTM D5706, the seizure resistance was evaluated by measuring the load at which seizure occurred. [Test conditions] Ball: Material SUJ2 steel, shape diameter 10 mm Plate: Material AISI52100 steel, roughness Ra = 0.28 μm Load: 50 N, 100 N, and then increasing by 100 N after 200 N Amplitude: 1 mm Frequency: 50 Hz Test temperature: 80 °C Speed: 100 mm / s Time: 2 minutes for each test load (increasing the load every 2 minutes) [Evaluation criteria] 〇 (Pass): The load at which seizure occurs is 1500 N or more × (Fail): The load at which seizure occurs is less than 1500 N

[0026]

Table 1

Claims

1. (a) a diurea-based thickener, (b) a base oil; (c) 0.1 to 10% by weight, based on the total weight of the composition, of an overbased calcium sulfonate, and (d) 0.01 to 5% by weight of disodium sebacate, based on the total weight of the composition; A grease composition comprising:

2. 2. The grease composition according to claim 1, wherein the base number of component (c) is 200 to 500 mg KOH / g.

3. 2. The grease composition according to claim 1, wherein component (a) is a diurea compound represented by the following formula (1): R 1 -NHGNH-R 2 -NHGNH-R 3 (1) (In the formula, R 1 and R 3 may be the same or different and are an alkyl group having 8 to 18 carbon atoms, an aryl group having 6 carbon atoms, or a cyclohexyl group. 2 is a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms.

4. The grease composition according to claim 1, further comprising at least one member selected from the group consisting of component (e-1) oil-insoluble molybdenum dialkyldithiocarbamate (MoDTC) and component (e-2) oil-soluble molybdenum dialkyldithiocarbamate (MoDTC).

5. The grease composition according to claim 4, comprising component (e-1) and component (e-2).

6. 2. The grease composition of claim 1, which is free of neutral zinc sulfonates.

7. The grease composition according to claim 1, which is for use in a constant velocity joint.

8. 2. The grease composition according to claim 1, which is for use in an outboard constant velocity joint.

9. A constant velocity joint filled with the grease composition according to any one of claims 1 to 8.

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