JP2000328085A - Lubricating grease composition for constant velocity joints - Google Patents

Abstract

(57) [Problem] To provide a novel grease composition for a constant velocity joint which can exhibit an excellent friction and wear reduction effect without using molybdenum sulfide dialkyldithiocarbamate. A grease comprising a base oil and a urea-based thickener comprises (A) an organic molybdenum complex of 0.1 to 10%.
% By weight, (B) sulfurized olefin, sulfur-phosphorus extreme pressure agent,
At least one additive comprising sulfur selected from the group consisting of ashless dithiocarbamate, polysulfide, thiadiazole, and zinc dithiocarbamate;
-5% by weight and (C) 0.1-5% by weight of at least one additive comprising phosphorus selected from the group consisting of molybdenum dithiophosphate, zinc dithiophosphate and triphenylphosphorothionate. A grease composition for a constant velocity joint.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a constant velocity joint for an automobile.
ts (hereinafter abbreviated as CVJ).

[0002]

2. Description of the Related Art The temperature of a joint tends to increase due to an increase in the output of an automobile engine, a reduction in the size and weight of a CVJ, and an increase in mounting angle. In addition, since the plunging joint rotates in the CVJ while transmitting torque, a sliding resistance is generated in the axial direction, and this is a source of vibration and noise of the vehicle. To solve this problem, CVJ
Although structural measures have been studied, the use of low-friction grease is effective in reducing frictional resistance.

Conventionally, extreme pressure lithium soap grease containing molybdenum disulfide, sulfurized fats and oils, sulfided olefins, lead compounds and the like has been widely used for CVJ. Recently, the use of urea grease to which molybdenum sulfide dialkyldithiocarbamate excellent in frictional properties has been added has been increasing.

[0004] As these representative technologies, Japanese Patent Publication No. 4-3
No. 4590 discloses that urea grease contains at least one sulfur-phosphorus extreme pressure selected from sulfurized molybdenum dialkyldithiocarbamate, sulfurized oil and fat, sulfurized olefin, tricresyl phosphate, trialkylthiophosphate and zinc dialkyldithiophosphate. A grease composition for a constant velocity joint of an automobile, which contains an additive as an essential component, is disclosed.

Other techniques relating to urea grease are disclosed in Japanese Patent Publication No. 5-79280 and Japanese Patent Publication No. 8-23034.
JP-A-4-178499, JP-A-4-30430
0, JP-A-4-328198, JP-A-6-5728
3, JP-A-6-57284, JP-A-6-10087
8, JP-A-6-184585, JP-A-7-1970
No. 72, JP-A-8-41485, JP-A-9-1948
No. 71, JP-A-9-324190, JP-A-10-18
No. 3161, JP-A-10-273691, JP-A-10-237691
-273692, USP4,840,740, US
P5,160,645 and USP5,449,47
No. 1 and the like. Each of these techniques can be said to be a technique in which friction and wear are reduced by adding molybdenum sulfide dialkyldithiocarbamate to urea grease and further adding other additives such as zinc dithiophosphate together.

[0006] CVJ manufacturers strongly demand grease manufacturers to reduce the cost of grease.
On the other hand, in order to improve the vibration characteristics of CVJ, there is a need for a high-performance grease that is effective in further reducing friction.

However, since molybdenum sulfide dialkyldithiocarbamate, which has an effect of reducing friction and wear, is expensive, it has been difficult to reduce the cost of grease using this additive. On the other hand, even if the above-mentioned molybdenum sulfide dialkyldithiocarbamate is used, it is difficult to escape from the level described in each of the above-mentioned patent specifications, and this technique is considered to be almost at its limit.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a novel grease composition for a constant velocity joint which can exhibit an excellent friction and wear reducing effect without using molybdenum sulfide dialkyldithiocarbamate. It is in.

[0009]

The present inventors have developed ASTM D5707, SRV (Schwingung Reibun Ung) standardized as a test method for evaluating the friction and wear characteristics of grease for constant velocity joints.
d Verschleiss) A grease composition of various compositions was prepared and tested using a testing machine to find a novel lubricating grease composition for constant velocity joints that exhibited a friction and wear reduction effect superior to conventional greases. Successful.

That is, the present invention relates to a grease comprising a base oil and a urea thickener, (A) 0.1 to 10% by weight of an organic molybdenum complex, (B) sulfurized olefin, sulfur-phosphorus extreme pressure agent, ashless 0.1 to 5% by weight of at least one additive containing sulfur selected from the group consisting of dithiocarbamates, polysulfides, thiadiazoles and zinc dithiocarbamate; and (C) molybdenum dithiophosphate, zinc dithiophosphate and triphenyl A grease composition for a constant velocity joint, comprising 0.1 to 5% by weight of at least one additive containing phosphorus selected from the group consisting of phosphorothionates.

As the lubricating base oil used in the present invention, mineral oils and synthetic oils such as ester oils, ether oils, hydrocarbon oils and the like or mixed oils thereof can be used.

As the urea-based thickener, any urea compound can be used, and examples thereof include mono, di, tri, and tetraurea. Further, various thickeners containing a urea compound such as a urea / urethane compound and a urea / imide compound can be used.

The organic molybdenum complex as the component (A) of the present invention can be an organic molybdenum complex described in Japanese Patent Publication No. 5-66435. This organic molybdenum complex can be produced by reacting (a) a fatty oil having 8 to 24 carbon atoms, (b) diethanolamine and (c) a molybdenum source, the main components of which are represented by the following general formula:

Embedded image And general formula (2)

Embedded image [R in the general formulas (1) and (2) represents a fatty oil residue].

Fatty oils are glyceryl esters of higher fatty acids having 8 to 24 carbon atoms. As such esters, those commonly known as vegetable oils or animal oils can be used, and specific examples include oils derived from palm, corn, cottonseed, linseed, peanut, soybean and sunflower seeds. Can be. Similarly, beasts (cow,
Animal fat oils such as sheep) oil can be used.

The source of molybdenum is an oxygenated molybdenum compound which can react with the reaction product of fatty oil and diethanolamine to form an ester type molybdenum complex. Molybdenum sources include, among others, ammonium molybdate, molybdenum oxide and mixtures thereof.

The component (A) used in the present invention accounts for 0.1 to 10% by weight, preferably 0.5 to 5% by weight, based on the total urea grease. When the amount is less than 0.1% by weight, the effect of reducing friction is insufficient, and when the amount is less than 10% by weight.
There is no further increase in the effect beyond.

The component (B) used in the present invention is a sulfur-containing additive selected from the group consisting of sulfurized olefins, sulfur-phosphorus extreme pressure agents, ashless dithiocarbamates, polysulfides, thiadiazoles and zinc dithiocarbamates. Agent. The amount of the urea grease used alone or in the form of a mixture thereof is 0.1 to
It is 5% by weight, preferably 0.5 to 2% by weight. 0.1
If it is less than 5% by weight, the effect of reducing friction is insufficient, and if it exceeds 5% by weight, the effect is not further increased.

The component (C) used in the present invention is a phosphorus-containing additive selected from the group consisting of molybdenum dithiophosphate, zinc dithiophosphate, and triphenylphosphorothionate. The amount used is 0.1 to 5% by weight, preferably 0.5 to 2% by weight, based on the urea grease, alone or in the form of a mixture. If the amount is less than 0.1% by weight, the effect of reducing friction is insufficient, and if it exceeds 5% by weight, the effect is not further increased.

The composition of the present invention may contain various known additives such as an antioxidant, a rust inhibitor, an extreme pressure agent / antiwear agent, an oiliness improver, and a thickener.

[0020]

EXAMPLES The present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

The additives shown in Tables 1 and 2 were added to the base grease, and the mixture was treated with a three-roll mill to obtain greases of Examples and Comparative Examples. The composition and properties of the base grease are as follows. The base oil used was a purified mineral oil having a viscosity at 100 ° C. of about 11 mm ² / S.

I. Diurea grease In 5400 g of base oil, 1 mol of 4,4'-diphenylmethane diisocyanate (295.1 g) is reacted with 2 mol of octylamine (304.9 g), and the resulting urea compound is uniformly dispersed and treated. Consistency (25
C., 60 W): 301, grease having properties of drop point:> 270.degree. The content of urea compound is 10% by weight
It is.

II. Tetraurea grease 2 mol of 4,4'-diphenylmethane diisocyanate (514.67 g) and 1 mol of octylamine (132.99 g), 1 mol of laurylamine (190.54 g) and 1 mol of ethylenediamine in 5100 g of base oil (61.80 g), and the resulting urea compound is uniformly dispersed and treated to obtain a consistency (25 ° C., 60
W): 308, grease having properties of dropping point: 254 ° C. were obtained. The content of the urea compound was adjusted to 15% by weight.

III. Lithium soap grease Lithium 12-hydroxystearate (150 g) is dissolved in 1350 g of base oil, uniformly dispersed and treated, and the consistency (25 ° C., 60 W): 275, dropping point 199 ° C.
A grease having the following properties was obtained. The content of lithium soap is 10% by weight.

The grease compositions shown in Tables 1 and 2 were subjected to an SRV test by a method according to ASTM D5707, and the degree of friction and wear was confirmed. Test conditions Test piece: Standard pole Diameter 10 mm (Material DIN 100Cr6) Standard plate Diameter 24 x thickness 7.85 mm (Material DIN 100Cr6) Load / time Run-in at 50 N for 30 seconds, 200 N for 30 minutes Frequency 50 Hz Test temperature 50 ° C. Coefficient of friction Average coefficient of friction for the last 15 seconds at the end of the test

In the table, 1) to 10) are as follows. 1) Mo-Complex (Molybdenum Complex) is MOLYVAN855 (Vanderbilt)
Company name, product name). 2) Sulfurized olefins are available from Anglamol 33 (L
ubrizol, trade name). 3) Sulfur-phosphorus system is available from Anglamol 99M (L
ubrizol, trade name). 4) Ashless dithiocarbamate is Vanlube 7
723 (trade name, manufactured by Vanderbilt). 5) Polysulfide is TPS32 (France e)
lf ATOCHEM (trade name). 6) Thiadiazole is available from Vanlube 829 (V
anderbilt (trade name). 7) Zn-DTC (zinc dithiocarbamate)
Vanlube Az (trade name, manufactured by Vanderbilt). 8) Mo-DTP (molybdenum dithiophosphate) was obtained from Sakuralube 300 (manufactured by Asahi Denka Co., Ltd.)
(Product name). 9) Zn-DTP (zinc dithiophosphate)
Is a product name of Lubrizol Co., Ltd.). 10) TPPT (triphenylphosphorothionate)
Is IRGALUBETTPPT (CIBA-GEIGY
Company name, product name).

[0027]

[Table 1]

[0028]

[Table 2]

<Evaluation> Examples 1 to 8 show results excellent in abrasion resistance and friction coefficient. On the other hand, Comparative Examples 1 to
10 is an organic molybdenum complex as the component (A) alone, a combination of the component (A) and the specific sulfur-containing additive as the component (B), and a combination of the component (A) and the component (C). The SRV test was performed on a grease using a combination with a limited phosphorus-containing additive. Comparative Example 11 corresponds to Example 7, except that the base uses lithium soap grease. As a result, it can be seen that lithium soap grease has a large wear resistance and a high friction coefficient, and has no effect of reducing friction and wear.

[0030]

According to the present invention, a lubricating grease composition for a constant velocity joint having an excellent coefficient of friction and abrasion resistance can be obtained. In particular, according to the present invention, ASTM D570
7 has a coefficient of friction of 0.075 or less, preferably 0.
070 or less, and a lubricating grease composition for constant velocity joints having an average wear scar diameter (mm) of the ball of 0.50 or less, preferably 0.45 or less can be obtained.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C10N 10:04 10:12 30:06 40:04 50:10 (72) Inventor Ryuichi Masumori Tokyo Showa Shell Sekiyu K.K., F-term (reference) 2-3-2 Daiba, Minato-ku, Tokyo 4H104 AA13R BB17R BB35C BE04R BE11C BE13B BG02C BG07C BG10C BG11C BG17C BG19C BH06C BH07C BH12C CE14B DA02 FA02 PA02

Claims (1)

[Claims] 1. A grease comprising a base oil and a urea thickener, wherein (A) an organic molybdenum complex of 0.1 to 10
% By weight (B) at least one additive containing sulfur selected from the group consisting of sulfurized olefins, sulfur-phosphorus extreme pressure agents, ashless dithiocarbamates, polysulfides, thiadiazoles, and zinc dithiocarbamate 5% by weight and (C) 0.1-5% by weight of at least one additive comprising phosphorus selected from the group consisting of molybdenum dithiophosphate, zinc dithiophosphate and triphenylphosphorothionate. Characteristic grease composition for constant velocity joints.