JP3320598B2 - Grease composition for constant velocity joints - Google Patents

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 extreme pressure grease containing molybdenum disulfide, molybdenum disulfide and sulfur-phosphorus extreme pressure agent, and naphthenic acid. And lithium-based extreme pressure greases containing a lead salt. 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 lubrication characteristic (friction coefficient, abrasion) by various extreme pressure additives, solid lubricants or a combination of each additive was examined using a vibration friction wear tester known as a tester. As a result, the present inventors have developed a grease composition comprising a base oil, a urea-based thickener, molybdenum disulfide, and a specific combination selected from a calcium salt and an overbased calcium salt, and a specific sulfur- A grease composition containing a phosphorus-based extreme pressure agent or molybdenum dithiocarbamate has been found to exhibit desirable lubricating properties such as a low coefficient of friction and low wear.Moreover, in a durability test using an actual constant velocity joint, It has been confirmed that unlike the conventional grease for constant velocity joints, the occurrence of the flaking phenomenon 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 thickener, (c) molybdenum disulfide, and (d) calcium salt of oxidized wax, calcium salt of petroleum sulfonic acid, calcium salt of alkyl aromatic 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, comprising at least one member selected from the group consisting of overbased calcium salts. A preferred embodiment of the present invention, in addition to the above components (a) to (d),
(e) A grease composition for a constant velocity joint 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 the above (a) to (d)
A grease composition for constant velocity joints containing (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 Particularly preferred urea thickeners are aniline, aromatic amines such as p-toluidine, cyclohexylamine, or a mixture thereof, and a diurea compound obtained by reaction with a diisocyanate compound, and an aryl group in the diurea compound. Has 6 or 7 carbon atoms, and the ratio of the aryl group to the cyclohexyl group in the diurea compound is preferably 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 seizure of the joint.

The calcium salt or overbased calcium salt which is the component (d) used in the present invention is known as a metal-based detergent / dispersant or rust inhibitor used in 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 dinonylnaphthalenesulfonic acid and alkylbenzenesulfonic acid, salicylate , Calcium salts of phenates, overbased calcium salts of oxidized waxes, overbased calcium salts of petroleum sulfonic acids, overbased calcium salts of alkyl aromatic sulfonic acids, overbased calcium salts of salicylates, and phenates Overbased calcium salts.

The preferred metal-free sulfur-phosphorus extreme pressure agent which is the component (e) used in the present invention has a sulfur content of 15 to 35% by weight and a phosphorus content of 0.5 to 3% by weight. By adjusting the ratio of the sulfur component to the phosphorus component, excellent anti-wear performance and anti-seizure performance can be exhibited. 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. If both are less than the above ranges, the intended anti-abrasion performance and anti-seizure performance can be sufficiently exhibited, and it becomes difficult. As the component (e) used in the present invention, molybdenum dithiophosphate can also be used. Preferred examples of such molybdenum dithiophosphate include:
What is represented by the following formula is mentioned.

[0010]

Embedded image

Wherein 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, 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:
Represents an alkyl group having 1 to 24 carbon atoms, preferably 3 to 18 carbon atoms, m is 0 to 3, n is 4 to 1, and m + n = 4. The grease composition for a constant velocity joint of the present invention can contain an antioxidant, a rust inhibitor, an anticorrosive, and the like in addition to the above components.

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

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

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

[0017]

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 in 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 reacted for 30 minutes with good stirring, and then heated 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
Take 8.9 g and heat the mixture 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-mentioned container, and reacted for 30 minutes while stirring well. Then, with stirring,
The temperature was raised to 0 ° C., and after standing 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 the above Examples and Comparative Examples, the following grease base oils were used. 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 properties of these greases were evaluated by the following test methods, and the obtained results are shown in Table 1. <Consistency> According to ISO 2137 <Drop point> According to ISO 2176 <SRV test> Test piece Ball diameter 10mm (SUJ-2) Cylindrical plate diameter 24mm x 7.85mm (SUJ-2) Evaluation condition Load 300 N Frequency 15 Hz Amplitude 1000μm Time 10 minutes Test temperature 150 ° C Measurement item Maximum coefficient of friction Average wear scar diameter of ball Maximum wear depth of plate

<Actual Endurance Test on Actual Joint> An endurance test on the actual joint was carried out under the following conditions to evaluate the occurrence of flaking and the like. 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-based thickener, (c) molybdenum disulfide, and (d) oxidized oil. 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, Overbased calcium salts of alkyl aromatic sulfonic acids, overbased calcium salts of salicylates,
And at least one selected from the group consisting of overbased calcium salts of phenates and, if necessary, (e) a sulfur-phosphorus-based electrode selected from a metal-free sulfur-phosphorus-based extreme pressure agent and molybdenum dithiophosphate. Pressure agent, or
(f) By blending a specific amount of molybdenum dithiocarbamate, excellent anti-abrasion and anti-flaking effects are obtained, as can be seen from the results of Examples and Comparative Examples shown in Table 1.

[0023]

[Table 1] Table 1 Example 1 2 3 4 5 6 7 8 9 Combination 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 329 333 331 334 328 329 332 333 333 Drop point (℃) 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 Endurance test 17) ○ ○ ○ ○ ○ ○ ○ ○ ○ 18) ○ ○ ○ ○ ○ ○ ○ ○

[0024]

TABLE 2 TABLE 1 (Continued) implementation example comparisons Example 10 11 12 13 1 2 3 ^* formulation base grease 1) 93.5 93.0 - - 97.0 97.0 2) - - 94.0 93.0 - - Additives 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 (℃) 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 Endurance test 17) ○ ○ ○ ○ × × × 18) ○ ○ ○ ○ × × ×

1) Diurea grease using a diurea compound using cyclohexylamine and aniline as a monoamine 2) Diurea grease using a diurea compound using octylamine 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 calcium sulfonate (trade name: Sulfol)
6) Calcium salicylate (trade name: OSCA423, manufactured by Oska Chemical Co., Ltd.) 7) Calcium phenate (trade name: OLOA 218A, manufactured by Olonite Japan Co., Ltd.) 8) Overbased salt Calcium sulfonate (trade name: Lubr
izol 5283 Nippon Lubrizol) 9) Overbased salt calcium sulfonate (Bryt)
on C-400C Witco Corporation) 10) Sulfur-phosphorus extreme pressure agent (trade name: Mobilad G-305 Mobile Chemical Co.) 11) Molybdenum dithiophosphate (trade name: Molyva)
n L RTVanderbilt) 12) Molybdenum dithiocarbamate (trade name: Molyvan
13) Molybdenum dithiocarbamate (trade name: Molyvan)
822 RTVanderbilt) 14) Maximum friction coefficient 15) Average wear scar diameter after test (mm) 16) Plate maximum wear depth after test (μm) 17) Bench endurance test: Barfield joint 18) Bench Endurance test: Cross-groove joint (with flaking occurrence: x, no: ○) ^* Commercially available molybdenum disulfide, sulfur-phosphorus extreme pressure agent, grease containing lead naphthenate

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI C10M 129: 10 C10M 129: 10 129: 54 129: 54 135: 10 135: 10 159: 06 159: 06 159: 20) 159: 20) C10N 10:04 C10N 10:04 10:12 10:12 30:06 30:06 40:02 40:02 50:10 50:10 (56) References JP-A-4-304300 (JP, A) JP-A-6-57283 (JP, A) JP-A-4-279698 (JP, A) JP-A-6-184583 (JP, A) JP-A-3-31394 (JP, A) JP-A-5-9489 (JP, A) JP-A-4-328198 (JP, A) JP-A-6-57284 (JP, A) JP-A 8-120289 (JP, A) JP-A-2-20597 (JP, A) ( 58) Field surveyed (Int.Cl. ⁷ , DB name) C10M 169/00-169/06 C10M 115/08 C10M 125/22 C10M 129/10-129/14 C10M 129/54 C10M 135/10 C10M 143 / 18 C10M 159/06 C10M 159/20-159/24 C10N 10:04 C10N 10:12 C10N 30:06 C10N 40:02 C10N 50:10 F16D 3/20

Claims (6)

(57) [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 alkyl aromatic sulfonic acid, calcium salt of salicylate, calcium salt of phenate, overbased calcium of oxidized wax At least one selected from the group consisting of a salt, an overbased calcium salt of petroleum sulfonic acid, an overbased calcium salt of an alkyl aromatic sulfonic acid, an overbased calcium salt of salicylate, and an overbased calcium salt of phenate A grease composition for constant velocity joints, comprising: 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 a constant velocity joint according to claim 1, further comprising (f) molybdenum dithiocarbamate. 4. The composition according to claim 1, wherein the content of the urea thickener is 1 to 25% by weight and the content of molybdenum disulfide is 0.1% by weight.
The grease composition for a constant velocity joint according to claim 1, wherein the content of the calcium salt or the overbased calcium salt is 0.5 to 15% by weight, 5 to 5% by weight. 5. A urea thickener content of 1 to 25% by weight and a molybdenum disulfide content of 0.1% by weight in the whole composition.
3-5% by weight, the content of calcium salt or overbased calcium salt is 0.5-15% by weight, and the content of sulfur-phosphorus extreme pressure agent is 0.1-3% by weight. The grease composition for a constant velocity joint according to the above. 6. The total composition has a urea thickener content of 1 to 25% by weight and a molybdenum disulfide content of 0.1% by weight.
The constant velocity according to claim 3, wherein the content of the calcium salt or the overbased calcium salt is 0.5 to 15% by weight, and the content of the molybdenum dithiocarbamate is 0.1 to 5% by weight. Grease composition for joints.