JPH09324189A - Grease composition for constant velocity joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a grease composition for a constant velocity joint comprising a base oil, a specific thickener, an extreme-pressure additive, a calcium salt, an extreme-pressure agent and a molybdenum dithiocarbamate and excellent in properties for preventing a flaking and a wearing and thermal stability. SOLUTION: This grease composition for a constant velocity joint comprises (A) a base oil, (B) a urea-based thickener, (C) molybdenum disulfide, (D) a calcium salt such as calcium (over based) salts of an oxidized wax, a petroleum sulfonic acid, an alkyl aromatic sulfonic acid, salicylate and phenate, (E) a sulfur-phosphorus-based extreme-pressure agent containing no metal and (F) a molybdenum dithiocarbamate such as a compound of the formula (R<1> R<2> N-CS- S)2 Mo2 OmSn [R<1> and R<2> are each a 1-24C alkyl, especially a 3-18C alkyl; (m) is 0-3 and (n) is 1-4 with the proviso that (m)+(n) is 4] and preferably contains 1-25wt.% component B, 0.5-5wt.% component C, 0.5-15wt.% component D, 0.1-3wt.% component E and 0.1-5wt.% component F.

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. Extremely high surface pressure is generated in the lubricated constant velocity joint part, and the joint part
It receives a complicated rolling and sliding action. As a result, abnormal wear and metal fatigue occur, causing a peeling phenomenon, that is, flaking of the joint. 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 extreme pressure greases containing molybdenum disulfide and using lithium soap as a thickener, and molybdenum disulfide containing sulfur-phosphorus-based grease. Examples of extreme pressure grease include lithium soap as a thickener by adding an extreme pressure agent or a lead salt of naphthenic acid. However, these constant velocity joint greases are not always satisfactory under the severe working conditions generated in recent high-performance automobiles. Recently, the number of four-wheel drive (FF type) automobiles has been rapidly increasing. The constant velocity joints used in these automobiles must be as light and small as possible. 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. Due to the higher output of engines in recent years, the surface pressure is higher than that of conventional engines, the weight of automobiles is reduced to improve fuel efficiency, and the size of joints is becoming smaller. For this reason, the surface pressure becomes relatively high, and the conventional grease cannot sufficiently prevent the flaking phenomenon. In addition, it has become necessary to improve the heat resistance of grease.

[0003]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a novel grease composition for constant velocity joints, which has excellent anti-flaking performance and heat resistance.

[0004]

The present inventors have optimized the wear of constant velocity joints to solve the problem of joint flaking due to abnormal wear and metal fatigue, and provide a grease composition having excellent heat resistance. Various studies were conducted to develop it. Performance evaluation of grease used under the lubrication condition with complicated rolling and sliding reciprocating motion under high surface pressure as described above,
SRV (Schwingung) known as a vibration friction wear tester
Reibung und Verschleiss) testing machine 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 inventors have found that base oils, urea thickeners, molybdenum disulfide, calcium salts or overbased calcium salts of specific compounds, metal-free sulfur-phosphorus extreme pressure agents, and molybdenum dithiocarbamate. It has been found that the grease consisting of the following shows desirable lubrication characteristics such as low friction coefficient and low wear.In addition, in the durability performance test using an actual constant velocity joint, unlike the conventional constant velocity joint grease, After confirming that the occurrence of the king phenomenon can be prevented, the present invention has been completed.

The above object of the present invention can be effectively achieved by a grease composition for constant velocity joints comprising the following components. (a) Base oil, (b) Urea thickener, (c) Molybdenum disulfide, (d) Calcium salt of oxidized wax, calcium salt of petroleum sulfonic acid, calcium salt of alkylaromatic sulfonic acid, calcium salicylate 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 overbased calcium salt. At least one calcium salt selected from the group consisting of basic calcium salts, (e) a metal-free sulfur-phosphorus extreme pressure agent, and (f) molybdenum dithiocarbamate.

[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 thickener as the component (b) used in the present invention include, but are not 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 the reaction of diisocyanate and 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%.

Molybdenum disulfide, which is the component (c) used in the present invention, is generally widely used as an extreme pressure additive, and since its lubrication mechanism has a layered lattice structure, it forms a thin layer under sliding motion. It easily shears, reduces friction, and is effective in preventing seizure of joints. Molybdenum disulfide having various particle diameters is known, and an average particle diameter by Fisher Sub-sieve sizer known as the Fischer method is 0.25 to 10 μm, especially
Those having an average particle size of 0.55 to 0.85 μm are suitable.

The calcium salt or the overbased calcium salt, which is the component (d) used in the present invention, is known as a metal-based detergent-dispersant and a rust preventive used for lubricating oil such as engine oil, 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 sufficiently exert the desired wear prevention performance and seizure prevention performance.

Preferred examples of molybdenum dithiocarbamate which is the component (f) used in the present invention include those represented by the following formula. (R ¹ R ² N-CS-S) ₂ Mo ₂ OmSn (In the formula, R ¹ and R ² each independently have 1 to 2 carbon atoms.
4, preferably 3 to 18 alkyl groups, m is 0 to
3, n is 4-1 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: 52 to 97.8% by weight, (b) component urea-based thickener: 1 to 25% by weight, (c) component molybdenum disulfide: 0.5 to 5% by weight, (d) Calcium salt or overbased calcium salt as component: 0.5 to 15% by weight, (e) metal-free sulfur-phosphorus extreme pressure agent: 0.1 to 3% by weight, (f) Ingredient molybdenum dithiocarbamate: 0.1-
It contains 5% 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. When the content is more than 25% by weight, the obtained composition becomes too hard and the desired effect is obtained. It gets harder. The content of component (c) is less than 0.5% by weight, and the content of component (d) is 0.5.
If the content is less than 0.1% by weight, the content of the component (e) is less than 0.1% by weight, or the content of the component (f) is less than 0.1% by weight, it is difficult to obtain the desired effect. c) The content of ingredients is 5
When the content of the component (d) is more than 15% by weight, the content of the component (e) is more than 3% by weight, or the content of the component (f) is more than 5% by weight. The effect is not increased, and the anti-flaking effect is rather the opposite effect.

[0013]

EXAMPLES Next, the present invention will be described with reference to Examples and Comparative Examples. [Examples 1 to 9 and Comparative Examples 1 to 3] 4100 g of base oil in a container
And diphenylmethane-4,4'-diisocyanate 10
12 g were taken and the mixture was heated to 70-80 ° C. In a separate container, 4100 g of base oil and 563 g of cyclohexylamine,
225 g of aniline was taken, heated to 70 to 80 ° C., and added to the above 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. 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.

Example 10 440 g of base oil and 58.9 g of diphenylmethane-4,4'-diisocyanate were placed in a container, 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, and add 70-80
After heating to 0 ° C, add to the previous container and stir well.
Allowed to react for minutes. Thereafter, while stirring, the temperature was raised to 160 ° 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, as the base oil of grease,
A mineral oil having the following properties was used. Viscosity 40 ° C. 157 mm ² / s 100 ° C. 14 mm ² / s Viscosity index 88 Further, a commercially available lithium grease containing a sulfur-phosphorus extreme pressure agent and a lead salt of naphthenic acid in molybdenum disulfide is used as Comparative Example 4
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 500 N Frequency 15 Hz Amplitude 3000 μm Time 10 minutes Test temperature 25 ℃ Measurement item Maximum friction coefficient Ball average wear scar diameter after test (mm) Maximum plate wear depth after test (μm)

<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 1000 rpm Torque 392 N ・ m Joint angle 8 ° Operating time 100 hours Joint type Barfield joint Cross groove joint Measurement item Flaking of joint parts after operation

[0017]

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 by blending at least one calcium salt selected from the group consisting of overbased calcium salts of phenates, (e) a metal-free sulfur-phosphorus extreme pressure agent, and (f) molybdenum dithiocarbamate, As can be seen from the results of the examples and comparative examples shown in Table 1, the excellent effects of preventing wear and flaking are exhibited.

[0018]

[Table 1] Table 1 Example 1 2 3 4 5 1) Diurea grease 94.0 94.0 93.5 93.5 94.0 2) Diurea grease − − − − − 3) Molybdenum disulfide 3.0 3.0 3.0 3.0 3.0 4) Oxide wax Ca 2.0 − − − − 5) Petroleum sulfonate Ca − 2.0 − − − 6) Naphthalene sulfonate Ca − − 2.0 − − 7) Calcium salicylate − − − 2.0 − 8) Calcium phenate − − − − 2.0 9) Calcium sulfonate − − − − − 10) Calcium sulfonate − − − − − 11) Sulfur-phosphorus extreme pressure agent 0.5 0.5 0.5 0.5 0.5 12) MDC 0.5 0.5 − − 0.5 13) MDC − − 1.0 1.0 − 14) Consistency 60w 321 327 335 326 329 15) Drop point (℃) 260 <260 <260 <260 <260 < 16) SRV test maximum friction coefficient 0.06 0.06 0.06 0.06 0.06 17) Ball average wear scar diameter (mm) 0.62 0.63 0.59 0.61 0.61 18) Plate maximum wear Depth (μm) 0.4 0.4 0.4 0.4 0.4 19) Durability test on bench ○ ○ ○ ○ ○ 20) Endurance test on bench ○ ○ ○ ○ ○

[0019]

[Table 2] (continued) Example 6 7 8 9 10 1) Diurea grease 94.0 93.5 94.0 92.5 − 2) Diurea grease − − − − 93.5 3) Molybdenum disulfide 3.0 3.0 3.0 3.0 3.0 4) Oxide wax Ca − − − − − 5) Petroleum sulfonate Ca − − − − − 6) Naphthalene sulfonate Ca − − 2.0 2.0 2.0 7) Calcium salicylate − − − − − 8) Calcium phenate − − − − − 9) Calcium sulfonate 2.0 − − − − 10) Calcium sulfonate − 2.0 − − − 11) Sulfur-phosphorus extreme pressure agent 0.5 0.5 0.5 0.5 0.5 12) MDC 0.5 − − − − 13) MDC − 1.0 0.5 2.0 1.0 14) Consistency 60w 332 325 328 324 317 15) Dropping point (℃) 260 <260 <260 <260 <260 < 16) SRV test maximum friction coefficient 0.06 0.06 0.06 0.06 0.06 17) Ball average wear scar diameter (mm) 0.60 0.60 0.61 0.61 0.62 18) Plate maximum wear depth (μm) 0.4 0.4 0.4 0.4 0.4 19) Bench durability test ○ ○ ○ ○ 20) Bench endurance test ○ ○ ○ ○ ○

[0020]

[Table 3] Comparative example 1 2 3 4 1) Diurea grease 97.0 98.0 98.0 2) Diurea grease − − − 3) Molybdenum disulfide 3.0 − − 4) Oxidized wax Ca − − − 5) Petroleum sulfonate Ca − − − 6) Naphthalene sulfonic acid Ca − 2.0 − 7) Calcium salicylate − − − 8) Calcium phenate − − − 9) Calcium sulfonate − − 2.0 10) Calcium sulfonate − − − 11) Sulfur-phosphorus extreme pressure agent − − − 12) MDC − − − 13) MDC − − − 14) Consistency 60w 324 321 321 280 15) Drop point (° C) 260 <260 <260 <190 16) SRV test maximum friction coefficient 0.15 <0.09 0.15 <0.15 <17 ) Ball average wear scar diameter (mm) Not measurable 0.63 Not measurable Not measurable 18) Maximum plate wear depth (μm) Not measurable 0.6 Not measurable Not measurable 19) Bench top durability test × × × × 20) Bench top durability test × × × ×

1) Diurea grease using a diurea compound using a mixture of cyclohexylamine and aniline as a monoamine 2) Diurea grease using a diurea compound using an 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 sulfonate calcium salt (trade name: Thulhol
Ca-45 Matsumura Petroleum Institute Co., Ltd.) 6) Calcium salt of dinonylnaphthalene sulfonate (Product name: NA-SUL 729 KING INDUSTRIES) 7) Calcium salicylate (Product name: OSCA423 Osca Chemical Co., Ltd.) 8) Calcium phenate (product name: OLOA 218A Oronite Japan Co., Ltd.) 9) Overbased calcium sulfonate (product name: Lubr
izol 5283 Lubrizol Japan 10) Overbased calcium sulfonate (trade name: Bryt
on C-400C Witco Corporation) 11) Sulfur-phosphorus extreme pressure agent (trade name: Anglamol 99, Lubrizol Japan) 12) MDC: molybdenum dithiocarbamate (trade name: Molyvan A RT Vanderbilt) 13 ) MDC: Molybdenum dithiocarbamate (Product name: Molyvan 822 RT Vanderbilt) 14) Consistency 60W 15) Drop point (° C) 16) Maximum friction coefficient 17) Ball average wear scar diameter after test (mm) 18) After test Plate maximum wear depth (μm) 19) Benchtop durability test: Barfield joint 20) Benchtop durability test: Cross groove joint (with flaking: ×, No: ○) ^* Commercially available molybdenum disulfide, sulfur − Grease containing phosphorus-based extreme pressure agent and lead naphthenate

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Claims (4)

[Claims] (1) a base oil, (b) a urea thickener,
(c) Molybdenum disulfide, (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 salt of oxidized wax. At least one selected from the group consisting of 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 a phenate. A grease composition for a constant velocity joint, comprising a calcium salt, (e) a metal-free sulfur-phosphorus extreme pressure agent, and (f) molybdenum dithiocarbamate. 2. The total composition has a urea thickener content of 1 to 25% by weight and a molybdenum disulfide content of 0.
5 to 5% by weight, the content of calcium salt or overbased calcium salt is 0.5 to 15% by weight, the content of sulfur-phosphorus extreme pressure agent is 0.1 to 3% by weight, the content of molybdenum dithiocarbamate The grease composition for constant velocity joints according to claim 1, wherein the amount is 0.1 to 5% by weight. 3. The grease composition for a constant velocity joint according to claim 1, wherein the sulfur-phosphorus extreme pressure agent containing no metal has a sulfur content of 15 to 35% by weight and a phosphorus content of 0.5 to 3% by weight. Stuff. 4. The grease composition for a constant velocity joint according to claim 2, wherein the sulfur-phosphorus extreme pressure agent containing no metal has a sulfur content of 15 to 35% by weight and a phosphorus content of 0.5 to 3% by weight. Stuff.