JPH08165488A - Grease composition for constant-velocity joint - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a grease composition for constant velocity joints having excellent anti-flaking performance and heat resistance. [Constitution] (a) Base oil, (b) Diurea compound represented by the following formula: R ¹ NH-CO-NH-C ₆ H ₄ -p-CH ₂ -C ₆ H ₄ -p-NH-CO- NHR ² (wherein R ¹ and R ² are the same or different and have 6 carbon atoms)
Or 7 is an aryl group or a cyclohexyl group), (c) molybdenum disulfide, and (d) a sulfur content of 15 to 3
A grease composition for a constant velocity joint, comprising a metal-free extreme pressure additive having a phosphorus content of 5% by weight and a phosphorus content of 0.5 to 3% by weight.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grease composition for constant velocity joints, and more particularly to a grease composition for plunging type constant velocity ball joints or fixed type constant velocity ball joints. An extremely high surface pressure is generated in the lubricated constant velocity joint portion, and the joint portion is subjected to 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 capable of lubricating such a constant velocity joint, effectively reducing wear of the joint, and effectively preventing flaking of a 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. The double offset type constant velocity joints and cross groove type constant velocity joints used as plunging type constant velocity ball joints, and the bar field joints used as fixed type constant velocity ball joints are all 6 It has a structure that transmits torque with a ball. In these constant velocity joints, the complex reciprocating motion of rolling and sliding under high surface pressure during rotation repeatedly applies stress to the ball and the metal surface in contact with the ball, and the 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. Further, it is also 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 present inventors have found that a grease comprising a specific combination of a base oil, a diurea compound, molybdenum disulfide and a metal-free extreme pressure additive exhibits desirable lubricating properties such as a low coefficient of friction and low wear. In addition to the finding, in an endurance performance test using an actual constant velocity joint, it was confirmed that unlike conventional greases for constant velocity joints, the occurrence of the flaking phenomenon could be prevented, and the present invention was completed. It was

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) Diurea compound represented by the following formula: R ¹ NH-CO-NH-C ₆ H ₄ -p-CH ₂ -C ₆ H ₄ -p-NH-CO-NHR ² ( In the formula, R ¹ and R ² are the same or different aryl groups having 6 or 7 carbon atoms or cyclohexyl groups), (c) molybdenum disulfide, and (d) sulfur content 15 to
A metal-free extreme pressure additive with 35% by weight and a phosphorus content of 0.5-3% by weight.

The base oil of the component (A) used in the present invention is a commonly used lubricating oil such as mineral oil, ester synthetic oil, ether synthetic oil, hydrocarbon synthetic oil or a mixture thereof. Oils are included, but are not limited to. In the diurea compound acting as a thickener (component (B)), the aryl group 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 mol%. Is. The diurea compound is obtained by reacting an aromatic amine such as aniline or p-toluidine, cyclohexylamine, or a mixture thereof with a diisocyanate compound.

The diurea grease composition of the present invention using this diurea compound has a difference in the micelle structure of the thickener as compared with diurea grease using an aliphatic amine and lithium soap grease, and the harsh lubrication conditions It has a micellar structure that is stable even under low shear and high surface pressure. In addition to acting as a thickener, it adheres to the metal surface and prevents metal-to-metal contact and wear. Further, the diurea grease composition of the present invention is also excellent in heat resistance. Next, 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 and reduces friction, and is effective in preventing joint seizure. Known as the Fisher method, molybdenum disulfide with various particle sizes is known as Fisher Sub-sieve sizer.
Those having an average particle diameter of 0.25 to 10 μm, particularly those having an average particle diameter of 0.55 to 0.85 μm are suitable.

Next, the component (D) used in the present invention,
The sulfur-phosphorus extreme pressure additive containing no metal has a sulfur component of 15 to 35% by weight, a phosphorus component of 0.5 to 3% by weight, and a balance of the component ratio of the sulfur component and the phosphorus component,
It exhibits excellent anti-wear and anti-seizure properties. Therefore, if the sulfur component is more than the above range, the joint is likely to be corroded, and if the phosphorus component is more than the above range, the wear of the joint increases, the wear preventing effect cannot be obtained, and if both are less than the above range,
The intended effect of the present invention cannot be obtained. Organic molybdenum compounds, organic zinc compounds, organic lead compounds, vegetable fats and oils are widely used as extreme pressure additives and oiliness agents. But,
The grease composition of the present invention comprises (A) a base oil, (B) a specific diurea compound, (C) molybdenum disulfide, and (D) a metal-free sulfur-phosphorus extreme pressure additive mixed in a specific ratio. Therefore, adding these extreme pressure additives and oiliness agents to the grease composition of the present invention,
The desired effect of the present invention may be impaired. However, the grease composition for constant velocity joints of the present invention may contain an antioxidant, a rust preventive, and an anticorrosive in addition to the above components.

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: 67 to 94% by weight, (B) component diurea compound: 5 to 25% by weight, (C) component molybdenum disulfide: 1 to 5% by weight, (D) component metal Sulfur-phosphorus extreme pressure additive not containing: 0.1 to 3% by weight is contained. The grease composition for constant velocity joints of the present invention is more preferably based on the total weight of the grease composition: (A) component base oil: 74 to 88% by weight, (B) component diurea compound: 1
0 to 20% by weight, (C) component molybdenum disulfide: 2 to 4
%, Sulfur-phosphorus extreme pressure additive (D), which does not contain metal: 0.3 to 2% by weight. If the content of the component (B) is less than 5% by weight, the thickening effect is reduced and it becomes difficult to form a grease. If it is more than 25% by weight, the obtained composition becomes too hard and the desired effect is obtained. It gets harder. If the content of the component (C) is less than 1% by weight and the content of the component (D) 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,
Even if the content of the component (D) is more than 3% by weight, the effect is not increased, and the antiflaking effect is rather the opposite effect.

[0010]

EXAMPLES Next, the present invention will be described with reference to Examples and Comparative Examples. [Examples 1 to 3, Comparative Examples 1 and 2] 2050 g of base oil in a container
And diphenylmethane-4,4'-diisocyanate 50
6 g were taken and the mixture was heated to 70-80 ° C. In a separate container, 2050 g of base oil and 281.5 g of cyclohexylamine,
Aniline (112.5 g) was taken, heated to 70 to 80 ° C., and added to the above container. The mixture is allowed to react for 30 minutes with good agitation, then heated to 160 ° C. with agitation,
After cooling, base urea grease was obtained. To this base grease, the additives having the composition shown in Table 1 were added, and the base oil was appropriately added, and the resulting mixture was adjusted to a consistency No. 1 grade with a three-stage roll mill.

Comparative Example 3 440 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 ℃, add to the previous container, while stirring well,
Let react for minutes. Then, with stirring, the temperature was raised to 160 ° C., and after cooling, a base aliphatic amine urea grease was obtained. To this base grease, the additives having the composition shown in Table 1 were added, and the base oil was appropriately added, and the resulting mixture was adjusted to a consistency No. 1 grade with a three-stage roll mill. [Comparative Example 4] To 500 g of base oil, 100 g of 12-hydroxystearic acid was added, heated to 80 ° C, 28 g of 50% lithium hydroxide aqueous solution was added with stirring, a saponification reaction was performed for 30 minutes, and then heated to 210 ° C. did. After the heat treatment, cool to 160 ° C., add 386 g of base oil,
It was cooled to 100 ° C. or lower with stirring to obtain a base lithium grease. To this base grease, the additives having the composition shown in Table 1 were added, and the base oil was appropriately added, and the resulting mixture was adjusted to a consistency No. 1 grade with a three-stage roll mill.

In each of the above Examples and Comparative Examples, the following base oils were used as grease. Type of base oil Mineral oil Viscosity 40 ° C. 156.6 mm ² / s 100 ° C. 14.4 mm ² / s Viscosity index 88 In addition, a commercially available molybdenum disulfide-containing lithium grease was used as the grease of Comparative Example 5, and commercially available molybdenum disulfide was mixed with sulfur. −
A lithium grease containing a phosphorus-based extreme pressure agent and a lead salt of naphthenic acid was used as the grease of Comparative Example 6.

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 90 minutes Test temperature 80 ℃ Measurement item Maximum coefficient of friction Average wear scar diameter of ball

<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 250 rpm Torque 1275 N ・ m Joint angle 6 ° Operating time 100 hours Joint type Barfield joint Cross groove joint Measurement item Flaking of joint parts after operation

[0015]

As described above, the grease composition for constant velocity joints of the present invention comprises (A) a base oil, (B) a specific diurea compound, (C) molybdenum disulfide, and (D) a metal. By blending a specific amount of the sulfur-phosphorus extreme pressure agent containing no sulfur, as shown in the results of Examples and Comparative Examples shown in Table 1, an excellent anti-wearing effect and anti-flaking effect are exhibited.

[0016]

[Table 1] Examples Comparative examples 1 2 3 1 2 3 4 5 ^* 6 ^** Compound base grease 1) 96.5 96.5 96.5 97.0 97.0 − − − − 2) − − − − − 96.5 − − − 3) − − − − − − 96.5 − − Additive 4) 3.0 − − − − − − − − 5) − 3.0 − 3.0 − 3.0 3.0 − − 6) − − 3.0 − − − − − − 7) 0.5 0.5 0.5 − 0.5 0.5 0.5 − − Evaluation test Consistency 60W 321 322 324 318 327 319 325 283 280 Drop point (° C) 260 <260 <260 <260 <260 <242 191 200 190 SRV test 8) 0.07 0.06 0.07 0.08 0.20 0.15 0.16 0.07 0.19 9 ) 0.66 0.60 0.64 0.73 0.77 0.86 1.21 0.65 1.41 Endurance test 10) ○ ○ ○ ○ × × × × × × 11) ○ ○ ○ × × × × ○ ×

1) In the formula, diurea grease using a diurea compound in which R ¹ and R ² are a mixture of phenyl group and cyclohexyl group 2) aliphatic amine diurea grease 3) lithium grease 4) molybdenum disulfide (trade name: Molysulfide CLIMAX M
OLYBDENUM COMPANY average particle size 3.5 μm) 5) Molybdenum disulfide (trade name: Molysulfide CLIMAX M
OLYBDENUM COMPANY average particle size 0.7μm) 6) Molybdenum disulfide (Product name: Molysulfide CLIMAX M
OLYBDENUM COMPANY average particle size 0.45μm) 7) Metal-free sulfur-phosphorus extreme pressure agent (trade name: Angl
amo199 Lubrizol) 8) Maximum coefficient of friction 9) Average ball wear scar diameter after test (mm) 10) Tabletop durability test: Barfield joint 11) Tabletop durability test: Cross groove joint (flaking occurred: ×) , None: ○) ^* Commercial molybdenum disulfide-containing grease ^** Commercial molybdenum disulfide, sulfur-phosphorus extreme pressure agent-containing grease

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C10N 10:12 20:06 Z 30:06 40:04 50:10 (72) Inventor Yasushi Hatakeyama Kanagawa Fujisawa-shi, Tsujido Shindai 1-1 of 4 Kyodo Yushi Co., Ltd. inside the Tsujido factory

Claims (9)

[Claims] 1. A (a) base oil, (b) a diurea compound represented by the following formula: R ¹ NH-CO-NH-C ₆ H ₄ -p-CH ₂ -C ₆ H ₄ -p-NH- CO-NHR ² (wherein R ¹ and R ² are the same or different aryl groups having 6 or 7 carbon atoms or a cyclohexyl group), (c) molybdenum disulfide, and (d) a sulfur content of 15 to
A grease composition for a constant velocity joint, which comprises a metal-free extreme pressure additive having a phosphorus content of 35% by weight and a phosphorus content of 0.5 to 3% by weight. 2. The total composition has a diurea compound content of 5 to 25% by weight, a molybdenum disulfide content of 1 to 5% by weight, and a metal-free extreme pressure agent content of 0.1 to 10. 3% by weight
The grease composition for constant velocity joints according to claim 1. 3. The total composition has a diurea compound content of 10 to 20% by weight and a molybdenum disulfide content of 2 to 4.
The grease composition for a constant velocity joint according to claim 2, wherein the content of the extreme pressure agent containing no metal and the extreme pressure agent containing no metal is 0.3 to 2% by weight. 4. The grease composition for constant velocity joints according to claim 1, wherein the molybdenum disulfide has an average particle size of 0.25 to 10 μm measured by a Fischer sieve meter. 5. The grease composition for a constant velocity joint according to claim 1, wherein the molybdenum disulfide has an average particle size of 0.55 to 0.85 μm measured by a Fischer sieve meter. 6. The grease composition for a constant velocity joint according to claim 1, wherein the constant velocity joint is a plunging type ball joint. 7. The grease composition for a constant velocity joint according to claim 1, wherein the constant velocity joint is a fixed ball joint. 8. The grease composition for a constant velocity joint according to claim 5, wherein the constant velocity joint is a plunging type ball joint. 9. The grease composition for a constant velocity joint according to claim 5, wherein the constant velocity joint is a fixed ball joint.