Grease composition for constant velocity joints

Abstract

The present invention provides a grease composition for constant velocity joints comprising (a) a base oil, (b) a diurea-based thickener, (c) molybdenum dithiocarbamate, (d) molybdenum dithiophosphate, (e) a perbasic calcium sulfonate, and (f) a neutral zinc sulfonate. The composition of the present invention has excellent durability at high temperatures and vibration suppression.

Description

Technology Field

[0001] The present invention relates to a grease composition for constant velocity joints. Background Technology

[0002] In the automotive industry, FF vehicles are widely adopted for the purpose of vehicle environmental measures (CO2 reduction) and securing living space, and constant velocity joints (CVJ), which are indispensable for power transmission in FF vehicles, are widely used.

[0003] Among the types of CVJs, the plunging constant velocity joint performs complex rolling and sliding motions between internal parts to rotate at an angle. At this time, friction between internal parts generates axial sliding resistance, and if this resistance is large, it can cause vibration or noise.

[0004] With the recent increase in the power output of automobile engines, lubrication conditions within constant velocity joints are shifting toward higher surface pressure. As lubrication conditions become higher, wear tends to occur more easily within the constant velocity joint, which can lead to problems such as reduced durability (anti-flaking property) or worsening of vibration.

[0005] In addition, regarding related constant velocity joints, it has also been required to ensure durability at high temperatures.

[0006] As a grease with excellent vibration suppression performance, a grease for constant velocity joints is formed by combining molybdenum dithiocarbamate and molybdenum dithiophosphate additives with urea grease, or by mixing zinc dithiophosphate with these organic molybdenum compounds (see Patent Document 1), and a grease composition for constant velocity joints containing a base oil, a urea-based thickener, molybdenum dithiocarbamate, calcium sulfonate, and thiophosphate has been proposed (see Patent Document 2). Furthermore, as quietness is increasingly required recently, a grease composition for constant velocity joints is proposed that comprises a mixture of molybdenum dialkyldithiocarbamate, molybdenum dialkyldithiophosphate or molybdenum diaryl dithiophosphate, and ash-free dithiocarbamate or zinc dithiocarbamate, in addition to a grease composed of a base oil and a urea-based compound thickener (see Patent Document 3), a base oil, A composition for isokinetic joints containing a diurea-based thickener, molybdenum dialkyldithiocarbamate sulfide, zinc sulfonate, a sulfur-phosphorus-based extreme pressure agent, and vegetable oil has also been proposed (see Patent Document 4).

[0007] As a grease that also takes durability into account, a composition for constant velocity joints containing a base oil, a thickener, montan wax, zinc sulfonate, and molybdenum dialkyl dithiocarbamate has been proposed (see Patent Document 5).

[0008] As such, existing grease compositions for constant velocity joints have demonstrated excellent performance in vibration suppression and their durability at room temperature has been examined; however, on the other hand, it cannot be said that sufficient examination has been conducted regarding the issue of durability at high temperatures. Prior art literature

[0009] Japanese Public Patent No. Hei 5-79280, Japanese Published Patent No. Hei 11-172276, Japanese Published Patent No. 2009-235416, Japanese Published Patent No. 2011-37950, International Publication No. 2014 / 054797 The problem to be solved

[0010] Accordingly, the present invention aims to provide a grease composition having excellent durability and vibration suppression properties even at high temperatures. means of solving the problem

[0011] 1. (a) Giyu

[0012] (b) Diurea-based thickeners

[0013] (c) Molybdenum dithiocarbamate

[0014] (d) Molybdenum dithiophosphate

[0015] (e) Perbasic calcium sulfonate

[0016] (f) neutral zinc sulfonate

[0017] A grease composition for constant velocity joints comprising

[0018] 2. A grease composition according to claim 1, wherein the content of component (f) is 0.1 to 10 mass% based on the total mass of the composition.

[0019] 3. A grease composition according to claim 1 or 2, wherein the content of component (f) is 0.5 to 5 mass% based on the total mass of the composition.

[0020] 4. A grease composition according to any one of claims 1 to 3, wherein the content of component (f) is 0.8 to 3 mass% based on the total mass of the composition.

[0021] 5. A grease composition according to any one of claims 1 to 4, wherein the content of component (e) is 0.1 to 10 mass% based on the total mass of the composition.

[0022] 6. A grease composition according to any one of claims 1 to 5, wherein the content of component (e) is 0.2 to 5 mass% based on the total mass of the composition.

[0023] 7. A grease composition according to any one of claims 1 to 6, wherein the content of component (e) is 1.2 to 3.5 mass% based on the total mass of the composition.

[0024] 8. A grease composition as described in any one of claims 1 to 7, wherein component (b) is an aliphatic diurea-based thickener.

[0025] 9. A constant velocity joint containing the grease composition described in any one of claims 1 to 8. Effects of the invention

[0026] According to the present invention, a grease composition that has excellent durability even at high temperatures and is also excellent for suppressing vibration can be provided. Specific details for implementing the invention

[0027] (a) Giyu

[0028] The base oil that can be used in the composition of the present invention is not particularly limited, and mineral oil and / or synthetic oil may be used. Examples of synthetic oils include synthetic hydrocarbon oils such as polyα-olefins; phenyl ether oils such as pentaphenyl ether, tetraphenyl ether, monoalkyl tetraphenyl ether, dialkyl tetraphenyl ether, and alkyl diphenyl ether oils; alkylbenzene oils; ester oils such as monoester oils, diester oils, and aromatic ester oils; polyglycol oils; silicone oils; fluorine oils; ionic liquids, etc.

[0029] As the base oil of the present invention, it is preferable to use mineral oil for cost reasons. A base oil having mineral oil as the main component and mixed with synthetic oil may also be used.

[0030] When the base oil of the present invention is a mixture of mineral oil and synthetic oil, based on the total mass of the base oil, it is preferable that the mineral oil is 50 to 100 mass%, more preferable that it is 70 to 100 mass%, and even more preferable that it is 90 to 100 mass%.

[0031] The kinematic viscosity of the base oil of the present invention at 100°C is preferably 5 to 30 mm² / s, and more preferably 7 to 20 mm² / s. At less than 5 mm² / s, the durability tends to be insufficient because an oil film is not formed within the constant velocity joint, and at more than 30 mm² / s, the durability tends to decrease due to heat generation within the CVJ.

[0032] From the perspective of fluidity, the content of the base oil is preferably 50 to 100 mass% based on the total mass of the composition, more preferably 70 to 100 mass%, and even more preferably 80 to 100 mass%.

[0033] (b) Diurea-based thickeners

[0034] The diurea-based thickener that can be used in the present invention is represented by the following formula (1).

[0035] R 1 -NHCONH-R 2 -NHCONH-R 3 (1)

[0036] During the meal, R 2 is a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms, and R 2 As such, tolylene diisocyanate or diphenylmethane diisocyanate is preferred, and diphenylmethane diisocyanate is more preferred. R 1 and R 3 The groups may be identical or different and are straight-chain or branched alkyl groups having 6 to 30 carbon atoms, aryl groups having 6 or 7 carbon atoms, or cyclohexyl groups.

[0037] As the diurea compound of formula (1), R 1 and R 3 Aliphatic diurea compounds, all of which are alkyl groups having 6 to 30 carbon atoms, are preferred. Aliphatic diurea compounds can be obtained by reacting a diisocyanate with an aliphatic monoamine.

[0038] As a diurea compound of formula (1), R 1 and R3 A cycloaliphatic diurea compound is preferred in which one of the groups is an alkyl group having 6 to 30 carbon atoms and the other is a cyclohexyl group. Since the cycloaliphatic diurea compound is obtained by reacting a diisocyanate with a cycloaliphatic monoamine and an aliphatic monoamine, in practice, in addition to the cycloaliphatic diurea compound, it is a mixture containing an aliphatic diurea compound and a cycloaliphatic diurea compound.

[0039] R 1 and R 3 If either one is a cyclohexyl group, it is preferable that the other is a straight-chain alkyl group having 8 or 18 carbon atoms. In this case, the proportion of the cyclohexyl group to the total of the cyclohexyl group and the alkyl group is preferably 70 to 100 mol% from the perspective of fluidity, and more preferably 80 to 100 mol%.

[0040] As a thickener of the present invention, an aliphatic diurea compound is preferred in terms of durability.

[0041] In particular, among Equation (1), R 1 and R 3 Any one of them is an alkyl group having 8 to 30 carbon atoms, and R 2 A diurea compound that is diphenylmethane diisocyanate is preferred.

[0042] In particular, R in Equation (1) 1 and R 3 All are straight-chain alkyl groups having 8 or 18 carbon atoms, and R 2 A diurea compound that is diphenylmethane diisocyanate is preferred.

[0043] The viscosity of the grease composition of the present invention is preferably 250 to 400, more preferably 280 to 370, and even more preferably 310 to 340. Additionally, in this specification, the term "viscosity" refers to the viscosity of 60 times mixing. Viscosity can be measured according to JIS K 2220 7.

[0044] The content of the thickener is preferably 10 mass% or less based on the total mass of the composition, more preferably 5 to 10 mass%, and even more preferably 6 to 7 mass%, so that the viscosity of the grease composition can be set within the above range.

[0045] (c) Molybdenum dithiocarbamate (MoDTC)

[0046] Molybdenum dithiocarbamate that can be used in the present invention is a general term for organometallic load-bearing additives in which the metal group is molybdenum, and is generally widely used as an extreme pressure additive. A preferred example of molybdenum dithiocarbamate can be represented by the following formula (2).

[0047] [R 4 R 5 N-CS-S]2-Mo2O m S n (2)

[0048] During the meal, R 4 and R 5 The groups may be identical or different from each other and each independently represents a straight-chain or branched alkyl group having 1 to 24 carbon atoms, preferably 3 to 18, and m is 0 to 3, n is 4 to 1, and m+n=4.

[0049] Molybdenum dithiocarbamate exists in oil-soluble molybdenum dithiocarbamate (i.e., liquid at room temperature (about 25°C)) and non-oil-soluble molybdenum dithiocarbamate (i.e., solid at room temperature). Both can be used as the molybdenum dithiocarbamate of the present invention, but a combination of oil-soluble molybdenum dithiocarbamate and non-oil-soluble molybdenum dithiocarbamate is preferred because it provides excellent durability, suppression of heat generation and vibration within the CVJ.

[0050] The content of component (b) in the grease composition of the present invention is preferably 0.1 to 10 mass% based on the total mass of the composition for the purpose of vibration suppression, more preferably 0.5 to 5 mass%, and even more preferably 1 to 3 mass%. In addition, when including oil-soluble molybdenum dithiocarbamate and non-oil-soluble molybdenum dithiocarbamate, it is desirable to use the oil-soluble molybdenum dithiocarbamate and non-oil-soluble molybdenum dithiocarbamate in a mass ratio of preferably 4:6 to 10:0, more preferably 6:4 to 8:2, as this provides excellent vibration suppression.

[0051] (d) Molybdenum dithiophosphate (MoDTP)

[0052] Preferred examples of molybdenum dithiophosphate used in the present invention include those represented by the following formula (3).

[0053] [(R 6 O)(R 7 O)PS-S]2Mo2O m S n

[0054] (during food, R 6 and R 7 Each is independently an alkyl group having 1 to 24 carbon atoms or an aryl group having 6 to 30 carbon atoms, m is 0 to 3, n is 4 to 1, and m+n=4)

[0055] The content of component (d) in the grease composition of the present invention is preferably 0.1 mass% or more based on the total mass of the composition for durability, more preferably 0.1 to 5 mass%, and even more preferably 0.2 to 2 mass%.

[0056] (e) Perbasic calcium sulfonate

[0057] The perbasic calcium sulfonate used in the present invention is a calcium sulfonate having a basic value of 200 mgKOH / g or higher. From the perspective of durability, it is preferable that the basic value be 300 mgKOH / g or higher, and more preferable that it be 300 to 500 mgKOH / g. In addition, in the present invention, the basic value is a value measured in accordance with JIS K 2501.

[0058] As component (e), a calcium salt of a sulfonic acid having a lipophilic organic group may be used. Examples of such organic sulfonic acids include petroleum sulfonic acid obtained by the sulfonation of aromatic hydrocarbon components in lubricating oil fractions, and synthetic sulfonic acids such as dinonylnaphthalenesulfonic acid or heavy alkylbenzenesulfonic acid. As component (e), a calcium sulfonate that is superbasic due to calcium carbonate is preferred. In particular, an alkyl aromatic sulfonate containing calcium carbonate is preferred.

[0059] The content of component (e) in the grease composition of the present invention is preferably 0.1 to 10 mass% based on the total mass of the composition for durability, more preferably 0.2 to 5 mass%, and even more preferably 1.2 to 3.5 mass%.

[0060] (f) neutral zinc sulfonate

[0061] The neutral zinc sulfonate used in the present invention has a base value of 10 mg KOH / g or less.

[0062] The sulfonic acid constituting zinc sulfonate is the same as that described for component (e).

[0063] As a neutral zinc sulfonate, zinc dinonylnaphthalenesulfonate is preferred.

[0064] The neutral zinc sulfonate content in the grease composition of the present invention is preferably 0.1 to 10 mass% based on the total mass of the composition for durability, more preferably 0.5 to 5 mass%, and even more preferably 0.8 to 3 mass%.

[0065] It is desirable that the sum of component (e) and component (f) be 0.5 to 5 mass%, more preferably 1 to 3 mass%, based on the total mass of the composition, as this provides excellent heat resistance.

[0066] It is desirable that the mass ratio of component (e) and component (f) is (e):(f) = 9:1 to 1:9, as this provides excellent durability. It is more desirable that (e):(f) = 8:2 to 3:7, and even more desirable that (e):(f) = 7:3 to 4:6. In particular, it is desirable that the total of component (e) and component (f) is 1 to 3 mass% based on the total mass of the composition, and the mass ratio of component (e) and component (f) is (e):(f) = 7:3 to 4:6, as this provides excellent durability and heat resistance.

[0067] The grease composition of the present invention may include additives commonly used in grease as needed. The content of these additives is typically 0.1 to 5 mass%, preferably 0.5 to 3 mass%, based on the total amount of the grease composition.

[0068] Examples of such additives include, for instance, antioxidants such as amine-based, phenol-based, quinoline-based, sulfur-based, and zinc dithiophosphate; anti-corrosion agents such as zinc-based, carboxylic acid-based, carboxylate-based (especially dibasic salts such as sodium sebate, sodium azelaate, and sodium suberate), and amine-based; anti-wear agents such as sulfurized oils, sulfated olefins, phosphate esters, phosphite esters, and acidic phosphate esteramine salts; oily agents such as fatty acids, fatty acid esters, and phosphate esters; and solid lubricants such as graphite, polytetrafluoroethylene (PTFE), and zinc oxide.

[0069] It is desirable to include an antioxidant from the perspective of heat resistance.

[0070] As for the antioxidant, an amine-based antioxidant is preferred, and alkyldiphenylamine is more preferred. The content of the antioxidant is preferably 0.1 mass% or more based on the total mass of the composition, more preferably 0.1 to 2 mass%, and even more preferably 0.2 to 1 mass%.

[0071] As a composition of the present invention,

[0072] (a) Giyu

[0073] (b) Diurea-based thickeners

[0074] (c) Molybdenum dithiocarbamate

[0075] (d) Molybdenum dithiophosphate

[0076] (e) Perbasic calcium sulfonate

[0077] (f) neutral zinc sulfonate

[0078] (g) Antioxidant

[0079] It is desirable that it consists solely of.

[0080] At this time, based on the total mass of the composition, it is preferable that the content of each component is 80 to 100 mass% for (a), 6 to 7 mass% for (b), 1 to 3 mass% for (c), 0.2 to 2 mass% for (d), 0.5 to 3 mass% for (e), 0.8 to 3 mass% for (f), and 0.2 to 1 mass% for (g).

[0081] As a composition of the present invention, also,

[0082] (a) Giyu

[0083] (b) Aliphatic diuretic thickeners

[0084] (c) Molybdenum dithiocarbamate

[0085] (d) Molybdenum dithiophosphate

[0086] (e) Perbasic calcium sulfonates containing calcium carbonate with a base of 300 mgKOH / g or more

[0087] (f) neutral zinc sulfonate

[0088] (g) Amine-based antioxidant

[0089] It is desirable to include .

[0090] At this time, based on the total mass of the composition, it is preferable that the content of each component is 80 to 100 mass% for (a), 6 to 7 mass% for (b), 1 to 3 mass% for (c), 0.2 to 2 mass% for (d), 0.5 to 3 mass% for (e), 0.8 to 3 mass% for (f), and 0.2 to 1 mass% for (g).

[0091] As a composition of the present invention, also,

[0092] (a) Giyu

[0093] (b) Among the above formula (1), R 1 and R 3 Any one of them is a straight-chain alkyl group having 8 carbon atoms, and R 2 an aliphatic diurea-based thickener that is diphenylmethane diisocyanate

[0094] (c) A mixture of oil-soluble molybdenum dithiocarbamate and non-oil-soluble molybdenum dithiocarbamate

[0095] (d) Molybdenum dithiophosphate

[0096] (e) Calcium alkyl aromatic sulfonate containing calcium carbonate, with a base of 300–500 mgKOH / g

[0097] (f) Zinc dinonylnaphthalenesulfonate with a base of 10 mgKOH / g or less

[0098] (g) Alkyldiphenylamine

[0099] It is desirable to include.

[0100] At this time, based on the total mass of the composition, it is preferable that the content of each component is 80 to 100 mass% for (a), 6 to 7 mass% for (b), 1 to 3 mass% for (c), 0.2 to 2 mass% for (d), 0.5 to 3 mass% for (e), 0.8 to 3 mass% for (f), and 0.2 to 1 mass% for (g).

[0101] The grease composition of the present invention is applied to constant velocity joints. In particular, it is preferred to apply it to plunging-type constant velocity joints, especially tripod-type constant velocity joints and double offset-type constant velocity joints, and especially to inboard-side constant velocity joints, as this provides excellent durability and vibration suppression.

[0102] <Example>

[0103] [1] Preparation of grease compositions of Examples 1 to 7 and Comparative Examples 1 to 4

[0104] 1 mole of 4',4-diphenylmethane diisocyanate and 2 moles of octylamine were reacted in a base oil, heated and cooled, then additives were added in the proportions shown in Table 1 or Table 2, and kneaded with a 3-roll mill to prepare a grease composition with a mixing degree of 315. In addition, unless otherwise noted, the values ​​in Tables 1 and 2 represent mass% based on the total mass of the grease composition.

[0105] [2] Preparation of the grease composition of Comparative Example 5

[0106] According to the description of Example C4 of Patent No. 6470851, the grease composition of Comparative Example 5 was prepared.

[0107] In addition, the ingredients used in the preparation of the grease composition are as follows.

[0108] Giyu

[0109] · Mineral oil (kinematic viscosity at 100°C: 12.4 mm² / s)

[0110] · Mineral oil + Synthetic oil: Polyα-olefin (Kinetic viscosity at 100℃: 12.0 mm² / s)

[0111] <Additives>

[0112] · MoDTC (Insoluble): Molybdenum dithiocarbamate (ADEKA Sakuralube 600, manufactured by ADEKA)

[0113] · MoDTC (insoluble): Molybdenum dithiocarbamate (Molyvan A, manufactured by Vanderbilt, used in Comparative Example 5)

[0114] · MoDTC (Oil-soluble): Molybdenum dithiocarbamate (ADEKA Sakuralube 525, manufactured by ADEKA)

[0115] · MoDTP: Molybdenum Dithiophosphate (ADEKA Sakuralube 300, manufactured by ADEKA)

[0116] · MoDTP: Molybdenum dithiophosphate (manufactured by Molyvan L, Vanderbilt, used in Comparative Example 5)

[0117] ·Ca-sulfonate (perbasic): Calcium salt of an alkyl aromatic sulfonic acid (LUBRIZOL 5283C, manufactured by The Lubrizol Corporation, base value 375 mgKOH / g)

[0118] · Zn Sulfonate (Neutral): Zinc Dinonyl Naphthalene Sulfonate (NA-SUL ZS, manufactured by KING INDUSTRIES, base value 5 mgKOH / g)

[0119] · Antioxidant

[0120] [2] Durability evaluation

[0121] (1) SRV test (high load)

[0122] [Test Conditions]

[0123] Test speed: 11.9 mm / s (Frequency: 3.3 Hz, Stroke: 1.8 mm)

[0124] Test temperature: 90℃

[0125] Load: 5.5 GPa

[0126] Specimen: Ball (diameter 17.5 mm, SUJ-2) / Plate (SUJ-2, surface roughness Rz 0.5 µm)

[0127] [metewand]

[0128] ◎ (Pass): Coefficient of friction 0.08 or less

[0129] ○ (Pass): Coefficient of friction 0.08 or higher, 0.10 or lower

[0130] △ (Pass): Coefficient of friction greater than 0.10, 0.12 or less

[0131] × (Fail): Seizure or friction coefficient exceeding 0.12

[0132] (2) SRV test (low load)

[0133] [Test Conditions]

[0134] Test speed: 2.0 mm / s (Frequency: 3.3 Hz, Stroke: 0.3 mm)

[0135] Test temperature: 95℃

[0136] Load: 2.1GPa

[0137] Specimen: Ball (diameter 17.5 mm, SUJ-2) / Plate (SUJ-2, surface roughness Rz 5 µm)

[0138] [metewand]

[0139] ○ (Pass): Coefficient of friction 0.10 or less

[0140] △ (Pass): Coefficient of friction greater than 0.10, 0.14 or less

[0141] × (Fail): Seizing or friction coefficient of 0.14 or higher

[0142] [2] Vibration suppression evaluation

[0143] (1) TE77 exam

[0144] The TE77 tester is a vibration friction wear tester under sliding conditions. It has been reported that there is a relationship between vibration with a constant velocity joint as the source of vibration and the coefficient of friction under vibration conditions measured by the TE77 tester (Japanese Patent Publication No. 2010-065194). Accordingly, vibration suppression in a constant velocity joint was evaluated using the TE77 tester.

[0145] [Test Conditions]

[0146] Test speed: 16 mm / s (Frequency: 10 Hz, Stroke: 0.8 mm)

[0147] Test temperature: 40℃

[0148] Load: 1.2 GPa

[0149] Specimen: Ball (diameter 17.5 mm, SUJ-2) / Plate (SCM)

[0150] [metewand]

[0151] ○ (Pass): Coefficient of friction 0.07 or less

[0152] △ (Pass): Coefficient of friction greater than 0.07, 0.10 or less

[0153] × (Fail): Coefficient of friction exceeding 0.10

[0154] [Overall Evaluation]

[0155] ○ (Pass): Passed all of the above test results

[0156] × (Fail): One or more of the above test results are unsatisfactory

[0157] The results are shown in Table 1 and Table 2.

[0158] [Table 1]

[0159]

[0160] [Table 2]

[0161]

Claims

Claim 1 (a) base oil, (b) diurea-based thickener, (c) molybdenum dithiocarbamate, (d) molybdenum dithiophosphate, (e) perbasic calcium sulfonate, and (f) neutral zinc sulfonate, wherein component (c) comprises oil-soluble molybdenum dithiocarbamate which is liquid at 25°C and non-oil-soluble molybdenum dithiocarbamate which is solid at 25°C, wherein the mass ratio of the oil-soluble molybdenum dithiocarbamate to the non-oil-soluble molybdenum dithiocarbamate is oil-soluble molybdenum dithiocarbamate:non-oil-soluble molybdenum dithiocarbamate = 6:4 to 8:2, and the content of component (e) is 1.2 to 3.5 mass% based on the total mass of the composition, and component (e) and Grease composition for constant velocity joints, wherein the mass ratio of component (f) is (e):(f) = 7:3 to 1.1:1.

0. Claim 2 A grease composition according to claim 1, wherein the content of component (f) is 0.1 to 10 mass% based on the total mass of the composition. Claim 3 A grease composition according to claim 1 or 2, wherein the content of component (f) is 0.5 to 5 mass% based on the total mass of the composition. Claim 4 A grease composition according to claim 1 or 2, wherein the content of component (f) is 0.8 to 3 mass% based on the total mass of the composition. Claim 5 A grease composition according to claim 1 or 2, wherein component (b) is an aliphatic diurea-based thickener. Claim 6 A constant velocity joint containing the grease composition described in paragraph 1 or 2. Claim 7 delete Claim 8 delete Claim 9 delete

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