JPH09194871A - Grease composition for constant-velocity joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grease composition excellent in antiflaking performances and heat resistance. SOLUTION: This composition comprises a base oil, a urea-based thickener, molybdenum disulfide, and at least one member selected from the group consisting of calcium salts of oxidized waxes, calcium salts of petroleum sulfonic acids, calcium salts of alkyl aromatic sulfonic acids, calcium salicylate, calcium phenate, overbased calcium salts of oxidized waxes, overbased calcium salts of petroleum sulfonic acids, overbased calcium salts of alkyl aromatic sulfonic acids, overbased calcium salicylates, and overbased calcium phenates.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a grease composition for a constant velocity joint, and more particularly to a grease composition for a plunging type constant velocity ball joint or a fixed type constant velocity ball joint. The lubricating condition of the constant velocity joint is extremely high surface pressure, and as a result, a peeling phenomenon, that is, flaking of the joint due to occurrence of abnormal wear or metal fatigue is likely to occur. The present invention relates to a grease composition for a constant velocity joint that can lubricate such a constant velocity joint, effectively reduce the wear of the joint, and effectively prevent the occurrence of flaking in the lubricated portion. is there.

[0002]

2. Description of the Related Art Conventionally, lubricating greases used in such constant velocity joints include lithium-based extreme pressure grease containing molybdenum disulfide, molybdenum disulfide and sulfur-phosphorus extreme pressure agents, and naphthenic acid. The lithium-based extreme pressure grease containing the lead salt of However, these greases for constant velocity joints are not always satisfactory under the severe operating conditions that occur in recent high-performance automobiles. Double offset constant velocity joints and cross groove constant velocity joints used as plunging constant velocity ball joints, and bar field joints used as fixed constant velocity ball joints, etc. Has a structure that transmits torque with a ball. In these constant velocity joints, the ball and the metal surface in contact with the ball are repeatedly subjected to stress by the reciprocating motion of the rolling and sliding under a high surface pressure during rotation, and a flaking phenomenon due to metal fatigue is likely to occur. In recent years, the output of engines has been increased, and the weight of automobiles has been reduced to improve fuel efficiency.The size of joints has also been reduced, resulting in a relatively high surface pressure, and the conventional grease has been able to sufficiently prevent the flaking phenomenon. Can not.
In addition, it has become necessary to improve the heat resistance of grease.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a novel grease composition for a constant velocity joint having excellent anti-flaking performance and heat resistance performance.

[0004]

SUMMARY OF THE INVENTION The present inventors have developed a grease composition which optimizes wear of a constant velocity joint, prevents flaking of the joint due to abnormal wear and metal fatigue, and has excellent heat resistance. Therefore, various studies were conducted.
The performance evaluation of grease used under the lubrication conditions involving the complicated rolling sliding reciprocating motion under the high surface pressure as described above, focusing on the sliding motion, was carried out with the SRV (Schwingung Reibung u).
nd Verschleiss) A vibration friction wear tester known as a tester was used to examine the lubrication characteristics (friction coefficient, wear) of various extreme pressure additives, solid lubricants or combinations of each additive. As a result, the present inventors have found that a grease composition comprising a base oil, a urea thickener, molybdenum disulfide, and a specific combination selected from a calcium salt and an overbased calcium salt, and further a specific sulfur- A grease composition containing a phosphorus-based extreme pressure agent or molybdenum dithiocarbamate was found to exhibit desirable lubrication characteristics such as low friction coefficient and low wear, and further in a durability performance test using an actual constant velocity joint, It was confirmed that unlike conventional greases for constant velocity joints, the occurrence of flaking can be prevented, and the present invention has been completed.

The above object of the present invention can be effectively achieved by a grease composition for a constant velocity joint containing the following components. (a) base oil, (b) urea-based thickener, (c) molybdenum disulfide, and (d) calcium salt of oxidized wax, calcium salt of petroleum sulfonic acid, calcium salt of alkylaromatic sulfonic acid, salicylate Calcium salt, phenate calcium salt, oxidized wax overbased calcium salt, petroleum sulfonic acid overbased calcium salt, alkyl aromatic sulfonic acid overbased calcium salt, salicylate overbased calcium salt, and phenate A grease composition for a constant velocity joint, containing at least one selected from the group consisting of overbased calcium salts. A preferred embodiment of the present invention is, in addition to the above components (a) to (d),
(e) A grease composition for constant velocity joints containing a sulfur-phosphorus extreme pressure agent selected from a metal-free sulfur-phosphorus extreme pressure agent and molybdenum dithiophosphate. Another preferred embodiment of the present invention is (a) to (d) above.
A grease composition for a constant velocity joint, which contains (f) molybdenum dithiocarbamate in addition to the components.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As the base oil of the component (a) used in the present invention, commonly used lubricating oils such as mineral oil, ester synthetic oil, ether synthetic oil and hydrocarbon synthetic oil are used. Or a mixed oil thereof, but is not limited thereto. Examples of the urea-based thickener used in the present invention include, but are not particularly limited to, diurea compounds and polyurea compounds. The diurea compound is obtained, for example, by reacting a diisocyanate with a monoamine. Examples of the diisocyanate include phenylene diisocyanate, diphenyl diisocyanate, phenyl diisocyanate, diphenylmethane diisocyanate, octadecane diisocyanate, decane diisocyanate, and hexane diisocyanate.As the monoamine, octylamine, dodecylamine, hexadecylamine, octadecylamine, oleylamine Aniline, p-toluidine, cyclohexylamine and the like can be mentioned. The polyurea compound is obtained, for example, by reacting a diisocyanate with a diamine.
Examples of the diisocyanate include those similar to those used for producing a diurea compound, and examples of the diamine include ethylenediamine, propanediamine, butanediamine, hexanediamine, octanediamine, phenylenediamine, tolylenediamine, and xylenediamine. Can be A particularly preferred urea thickener is a diurea compound obtained by reacting an aromatic amine such as aniline and p-toluidine, cyclohexylamine, or a mixture thereof with a diisocyanate compound, and an aryl group in the diurea compound. Preferably has 6 or 7 carbon atoms and the ratio of the aryl group to the cyclohexyl group in the diurea compound is 100 to 0%.

Next, molybdenum disulfide, which is the component (c) used in the present invention, is generally widely used as an extreme pressure additive. As the lubrication mechanism, it is known that the lubrication mechanism has a laminar lattice structure, easily shears into a thin layer by a sliding motion, and lowers the friction coefficient. It is also effective in preventing burns on the joint.

The component (d) used in the present invention, which is a calcium salt or an overbased calcium salt, is known as a metal-based detergent-dispersant and a rust preventive used for lubricating oils such as engine oils. Calcium salt of oxidized wax, calcium salt of petroleum sulfonic acid obtained by sulfonation of aromatic hydrocarbon component in lubricating oil fraction, calcium salt of synthetic sulfonic acid such as dinonylnaphthalene sulfonic acid and alkylbenzene sulfonic acid, salicylate Calcium salt, phenate calcium salt, oxidized wax overbased calcium salt, petroleum sulfonic acid overbased calcium salt, alkyl aromatic sulfonic acid overbased calcium salt, salicylate overbased calcium salt, and phenate The overbased calcium salt of.

The component (e) used in the present invention, which is preferable as the metal-free sulfur-phosphorus extreme pressure agent, has a sulfur content of 15 to 35% by weight and a phosphorus content of 0.5 to 3% by weight. Therefore, by adjusting the ratio of the sulfur component and the phosphorus component, it is possible to exhibit excellent antiwear property and anti-burn property. If the sulfur component is more than the above range, the joint is likely to corrode, and if the phosphorus component is more than the above range, the effect of preventing the joint from being worn cannot be obtained. On the other hand, if both are less than the above range, it becomes difficult to achieve the desired wear prevention performance and burn-in prevention performance. As the component (e) used in the present invention, molybdenum dithiophosphate can also be used. Preferred examples of such molybdenum dithiophosphate include:
Examples include those represented by the following formula.

[0010]

Embedded image

(In the formula, R ¹ , R ² , R ³ and R ⁴ are each independently a primary or secondary alkyl group having 1 to 24 carbon atoms, preferably 3 to 20 carbon atoms, or 6 to 6 carbon atoms. It represents 30, preferably 8 to 18 aryl groups.)

Preferred examples of molybdenum dithiocarbamate which is the component (f) used in the present invention include those represented by the following formula.

Embedded image

(Wherein R ⁵ and R ⁶ are each independently
It represents an alkyl group having 1 to 24 carbon atoms, preferably 3 to 18, m is 0 to 3, n is 4 to 1, and m + n = 4. In addition to the above components, the grease composition for constant velocity joints of the present invention may contain an antioxidant, a rust preventive, an anticorrosive, and the like.

The grease composition for constant velocity joints of the present invention preferably contains, based on the total weight of the grease composition,
(a) Component base oil: 55.0-98.0% by weight, (b) Component urea thickener: 1-25% by weight, (c) Component molybdenum disulfide: 0.5-5% by weight %, (D) Calcium salt or overbased calcium salt: 0.5 to 15% by weight. The grease composition for constant velocity joints of the present invention,
More preferably, with respect to the total weight of the grease composition,
(a) Component base oil: 52.0-97.9% by weight, (b) Component urea thickener: 1-25% by weight, (c) Component molybdenum disulfide: 0.5-5% by weight %, (D) Calcium salt or overbased calcium salt: 0.5 to 15% by weight, (e)
Ingredient sulfur-phosphorus extreme pressure additive: 0.1 to 3% by weight is contained.

The other grease composition for constant velocity joints of the present invention is preferably a base oil of component (a): 50.0-97.9% by weight, (b) based on the total weight of the grease composition. )
Component urea thickener: 1 to 25% by weight, (c) Component molybdenum disulfide: 0.5 to 5% by weight, (d) Calcium salt or overbased calcium salt: 0.5 to 15% by weight ,
(f) Component molybdenum dithiocarbamate: 0.1 to 5% by weight is contained. The other grease composition for constant velocity joints of the present invention is more preferably a base oil of component (a): 63.0 to 91.5% by weight, and component (b) relative to the total weight of the grease composition. Urea thickener of 5: 20% by weight, (c) component molybdenum disulfide: 2-4% by weight, (d)
Calcium salt or overbased calcium salt: 1 to 10% by weight, (f) component molybdenum dithiocarbamate: 0.5 to
It contains 3% by weight.

When the content of the component (b) is less than 1% by weight, the thickening effect is reduced and it becomes difficult to form a grease.
If it is more than 5% by weight, the resulting composition becomes too hard,
It is difficult to obtain the desired effect. The content of the component (c) is less than 0.5% by weight, the content of the calcium salt or the overbased calcium salt of the component (d) is less than 0.5% by weight, and the content of the component (e) is 0.1. When the content of the component (f) is less than 0.1% by weight, it is difficult to obtain the desired effect, while the content of the component (c) is more than 5% by weight, ( d) When the content of the calcium salt or the overbased calcium salt of the component is more than 15% by weight, the content of the (e) component is more than 5% by weight, and the content of the (f) component is more than 5% by weight. Also,
There is no increase in effect, and in anti-flaking effect,
Rather, it is the opposite effect.

[0017]

EXAMPLES Next, the present invention will be described with reference to Examples and Comparative Examples. [Examples 1 to 11, Comparative Examples 1 and 2] Base oil 410 was added to a container.
0 g and 1012 g of diphenylmethane-4,4'-diisocyanate were taken and the mixture was heated to 70-80 ° C.
In a separate container, 4100 g of base oil and cyclohexylamine 563
g, 225 g of aniline and heated to 70-80 ° C.
Added to previous container. The mixture was allowed to react for 30 minutes with good stirring, and then the temperature was raised to 160 ° C. with stirring and allowed to cool to obtain a base urea grease. To this base grease, additives were added in the composition shown in Table 1, base oil was appropriately added, and the resulting mixture was subjected to three-stage roll milling using a three-stage roll mill.
The consistency was adjusted to No. 1 grade.

[Examples 12 and 13] Base oil 440 was added to a container.
g and diphenylmethane-4,4'-diisocyanate 5
8.9g was taken and the mixture was heated to 70-80 ° C. In a separate container, take 440 g of base oil and 61.1 g of octylamine,
After heating to 70 to 80 ° C., the mixture was added to the above container and reacted for 30 minutes while stirring well. Then, while stirring, 16
After raising the temperature to 0 ° C. and allowing to cool, a base aliphatic amine urea grease was obtained. Additives were added to this base grease in the composition shown in Table 1, and a base oil was added as appropriate. The resulting mixture was adjusted to a consistency No. 1 grade using a three-roll mill.

In each of the above Examples and Comparative Examples, the following base oils were used for grease. Type of base oil Mineral oil Viscosity 40 ° C 130 mm ² / s 100 ° C 14 mm ² / s Viscosity index 106 In addition, compare commercially available molybdenum disulfide with lithium grease containing sulfur-phosphorus extreme pressure agent and naphthenic acid lead salt. Example 3
Grease.

The physical properties of these greases were evaluated by the following test methods, and the obtained results are also shown in Table 1. <Consistency> According to ISO 2137 <Drop point> According to ISO 2176 <SRV test> Test piece Ball diameter 10 mm (SUJ-2) Cylindrical plate Diameter 24 mm × 7.85 mm (SUJ-2) Evaluation conditions Load 300 N Frequency 15 Hz Amplitude 1000 μm Time 10 minutes Test temperature 150 ℃ Measurement item Maximum friction coefficient Average wear scar diameter of ball Maximum wear depth of plate

<Actual joint bench endurance test> Under the following conditions, an actual joint bench endurance test was performed to evaluate whether flaking or the like occurred. Test conditions Rotation speed 200 rpm Torque 785 N · m Joint angle 7 ゜ Operating time 100 hours Joint type Bar field joint Cross groove joint Measurement item Whether or not flaking occurs at each joint after operation

[0022]

As described above, the grease composition for a constant velocity joint of the present invention comprises (a) a base oil, (b) a urea thickener, (c) molybdenum disulfide, and (d) an oxidation agent. Wax calcium salt, petroleum sulfonic acid calcium salt, alkyl aromatic sulfonic acid calcium salt, salicylate calcium salt, phenate calcium salt, oxidized wax overbased calcium salt, petroleum sulfonic acid overbased calcium salt, Alkyl aromatic sulfonic acid overbased calcium salt, salicylate overbased calcium salt,
And at least one selected from the group consisting of overbased calcium salts of phenates, and optionally (e) a sulfur-phosphorus-based pole selected from a metal-free sulfur-phosphorus extreme pressure agent and molybdenum dithiophosphate. Pressure agent, or
(f) By blending a specific amount of molybdenum dithiocarbamate, as shown in the results of Examples and Comparative Examples shown in Table 1, excellent anti-wearing and anti-flaking effects are exhibited.

[0023]

[Table 1] Table 1 Example 1 2 3 4 5 6 7 8 9 9 Compound base grease 1) 94.0 94.0 94.0 94.0 94.0 92.0 94.0 94.5 94.5 2) − − − − − − − − − Additive 3) 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 4) 3.0 − − − − − − 2.0 2.0 5) − 3.0 − − − − − − − 6) − − 3.0 − − − − − − 7) − − − 3.0 − − − − − 8) − − − − 3.0 5.0 − − − 9) − − − − − − 3.0 − − 10) − − − − − − − 0.5 − 11) − − − − − − − − 0.5 12) − − − − − − − − − 13) − − − − − − − − − Evaluation test consistency 60W 329 333 331 334 328 329 332 333 336 Dropping point (° C) 260 <260 <260 <260 <260 <260 <260 <260 <260 <SRV test 14) 0.06 0.06 0.07 0.06 0.07 0.06 0.07 0.07 0.06 15) 0.45 0.46 0.46 0.47 0.46 0.44 0.47 0.45 0.46 16) 0.3 0.3 0.3 0.2 0.3 0.3 0.4 0.3 0.3 Durability test 17) ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ 18) ○ ○ ○ ○ ○ ○ ○ ○

[0024]

[Table 2] Table 1 (continued) Example Comparison Example 10 11 12 13 1 2 3 ^* Compound base grease 1) 93.5 93.0 − − 97.0 97.0 2) − − 94.0 93.0 − − Additive 3) 3.0 3.0 3.0 3.0 3.0 − 4) − − − − − − 5) − − − − − − 6) − − − − − − 7) − − − − − − 8) 3.0 3.0 3.0 3.0 − 3.0 9) − − − − − − 10) − − − − − − 11) − − − − − − 12) 0.5 − − − − − 13) − 1.0 − 1.0 − − Evaluation test consistency 60W 324 328 322 324 315 332 280 Drop point (° C) 260 <260 <236 242 260 <260 <190 SRV test 14) 0.06 0.06 0.08 0.07 0.13 0.12 0.20 15) 0.47 0.46 0.49 0.47 0.51 0.54 0.53 16) 0.4 0.3 0.5 0.4 3.0 1.8 3.0 Durability test 17) ○ ○ ○ ○ × × × 18) ○ ○ ○ ○ × × ×

1) Diurea grease using a diurea compound in which cyclohexylamine and aniline are mixed as a monoamine 2) Diurea grease using a diurea compound in which octylamine is used as a monoamine 3) Molybdenum disulfide (trade name: Molysulfide CLIMAX M
OLYBDENUM COMPANY average particle size 0.7 μm) 4) Oxidized wax calcium salt (Product name: Alox 165 Alo)
x Corporation) 5) Petroleum sulfonate calcium salt (trade name: Thulhol
Ca-45 Matsumura Petroleum Institute Co., Ltd.) 6) Calcium salicylate (Product name: OSCA423 Osca Chemical Co., Ltd.) 7) Calcium phenate (Product name: OLOA 218A Oronite Japan Co., Ltd.) 8) Overbased salt Calcium sulfonate (trade name: Lubr
izol 5283 Nippon Lubrizol) 9) Overbased salt calcium sulfonate (trade name: Bryt
on C-400C Witco Corporation) 10) Sulfur-phosphorus extreme pressure agent (trade name: Mobilad G-305, Mobil Chemical Co.) 11) Molybdenum dithiophosphate (trade name: Molyva
n L RTVanderbilt) 12) Molybdenum dithiocarbamate (Product name: Molyvan
A RT Vanderbilt) 13) Molybdenum dithiocarbamate (Product name: Molyvan
822 RTVanderbilt) 14) Maximum friction coefficient 15) Average ball wear mark diameter after test (mm) 16) Maximum plate wear depth after test (μm) 17) Tabletop durability test: Barfield joint 18) Tabletop Durability test: Cross groove joint (flaking occurrence: ×, nothing: ○) ^* Commercial molybdenum disulfide, sulfur-phosphorus extreme pressure agent, lead naphthenate-containing grease

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C10M 115: 10 117: 08 115: 04 137: 10) C10N 10:04 10:12 30:06 40:04 50 :Ten

Claims (6)

[Claims] (1) a base oil, (b) a urea thickener,
(c) Molybdenum disulfide, and (d) Calcium salt of oxidized wax, calcium salt of petroleum sulfonic acid, calcium salt of alkylaromatic sulfonic acid, calcium salt of salicylate, calcium salt of phenate, overbased calcium of oxidized wax. At least one selected from the group consisting of salt, overbased calcium salt of petroleum sulfonic acid, overbased calcium salt of alkylaromatic sulfonic acid, overbased calcium salt of salicylate, and overbased calcium salt of phenate A grease composition for constant velocity joints, which comprises: 2. The constant velocity joint according to claim 1, further comprising (e) a sulfur-phosphorus extreme pressure agent selected from a metal-free sulfur-phosphorus extreme pressure agent and molybdenum dithiophosphate. Grease composition. 3. The grease composition for constant velocity joints according to claim 1, further comprising (f) molybdenum dithiocarbamate. 4. The total composition has a urea thickener content of 1 to 25% by weight and a molybdenum disulfide content of 0.
The grease composition for constant velocity joints according to claim 1, wherein the content of the calcium salt or the overbased calcium salt is 5 to 5% by weight, and the content thereof is 0.5 to 15% by weight. 5. The total composition has a urea thickener content of 1 to 25% by weight and a molybdenum disulfide content of 0.
The content of the calcium salt or the overbased calcium salt is 0.5 to 15% by weight, and the content of the sulfur-phosphorus extreme pressure agent is 0.1 to 3% by weight. The grease composition for constant velocity joints described. 6. The total composition has a urea-based thickener content of 1 to 25% by weight and a molybdenum disulfide content of 0.
The constant velocity according to claim 3, wherein the content of the calcium salt or the overbased calcium salt is 5 to 5% by weight, and the content of molybdenum dithiocarbamate is 0.1 to 5% by weight. Grease composition for joints.