KR100828176B1 - Grease composition having high durability and low friction force for constant velocity joints - Google Patents

Abstract

A grease composition for constant velocity joints having excellent durability and low-friction is provided to promote long-term durability and low-friction while improving an extreme pressure property and anti-wear property of the constant velocity joint. A grease composition for constant velocity joints having excellent durability and low-friction by a urea type thickener includes: a base oil selected from a paraffin-mineral oil and naphthene-mineral oil; the urea grease thickener; molybdenum dialkyldithiocarbamate; vegetable modified molybdenum anti-wear agents; zinc dialkyldithio-phosphate; calcium sulfurnates; amide wax; diphenylamine; and calcium salts.

Description

Grease Composition having high durability and Low friction force for Constant Velocity Joints}

The present invention relates to a grease composition for constant velocity joints having excellent durability and low friction, and more particularly, using a mixture of paraffinic mineral oil and naphthenic mineral oil refined with base oil, and for reducing urea-based grease thickener, anti-wear agent and friction. Dialkyl dithio carbamate, vegetable oil-modified molybdenum anti-wear agent, zinc dialkyl dithio phosphate, calcium sulfonate and amide wax, diphenylamine, calcium salt are mixed in a certain component ratio, the extreme pressure and abrasion resistance equivalent to or more than conventional A grease composition for constant velocity joints having excellent long-term durability and low friction while maintaining physical properties.

The constant velocity joint is a very important part of the car. It is connected between the car engine and the wheel by a drive shaft, and the wheel acts to transmit the driving force of the engine to the wheel at a constant speed even when the angle changes as the wheel moves forward, backward, left, and right.

Recently, automobiles have been developed with the trend of lighter weight, smaller size, and higher output. As a result, automotive constant velocity joints have become smaller and require longer life and low noise. Therefore, greases used in automobile constant velocity joints should be excellent in friction reduction to reduce vibration and noise and long-term durability for long-term use over 10 years.

Generally, low friction of grease requires low friction of grease and good shear stability is required for long term use of grease. Low friction requires low coefficient of friction and abrasion, and shear stability is important for other physical properties. Stability and miscibility should be excellent. In addition, constant velocity joints are exposed to the outside, so the mixing of water is expected, so the resistance to water should be excellent.

In the constant velocity joint grease composition, the base oil occupies about 70 to 90% by weight, so the base oil plays a lubricating role, but in order to grease the grease for a long time, the grease must maintain a semi-solid state as a grease for a long time. At this time, the substance which maintains the semi-solid state as grease is a thickener. If the thickener does not maintain a semi-solid state, the semi-solid state of the grease is changed into a liquid form, and finally, the oil is easily leaked and the adhesion is degraded, thereby reducing the lubricating performance, which eventually causes inoperability.

In addition, the grease used in the constant velocity joint of the automobile needs friction reduction to reduce vibration and noise, and when the friction force drops, the wear inside the constant velocity joint becomes severe and abnormal vibration and noise may be generated to shorten the life of the automobile.

However, in the past, greases for automobile constant velocity joints have been developed mainly for extreme pressure resistance and abrasion resistance [Korea Patent Registration No. 0541148]. They did not consider long-term durability and low friction, which caused shortening of lifespan.

Overall, greases for automotive constant velocity joints are preferably accompanied by extreme long term durability and low friction as well as extreme pressure and wear resistance.

Accordingly, the present inventors have made efforts to improve the problem of shortening the lifespan of greases for automobile constant velocity joints, which are developed to improve physical properties such as extreme pressure resistance and wear resistance. As a result, a mixture of paraffinic mineral oil and naphthenic mineral oil refined with base oil is used, and a molybdenum dialkyldithiocarbamate, vegetable oil-modified molybdenum antiwear agent, and zinc dialkyldithiophosphate are used for reducing urea grease thickener, antiwear agent and friction. , Calcium sulfonate and amide wax are selected, and diphenylamine and calcium salt are mixed in a certain component ratio to maintain physical properties such as extreme pressure and abrasion resistance that are equivalent to those of the prior art, and at the same time, excellent durability and low friction. It was found that the present invention was completed.

Accordingly, an object of the present invention is to provide a grease composition for automobile constant velocity joints excellent in long-term durability and low friction.

The present invention is 1) a base oil selected from paraffinic mineral oil and naphthenic mineral oil, 2) urea grease thickener represented by the following formula (1), 3) molybdenum dialkyldithiocarbamate, 4) vegetable oil modified molybdenum antiwear agent, 5) zinc It is characterized by a grease composition for automobile constant velocity joints containing dialkyldithiophosphate, 6) calcium sulfonate, 7) amide wax, 8) diphenylamine, and 9) calcium salt.

In said Formula (1), R <_1> and R <_2> represents a C6-C7 aromatic hydrocarbon, a cyclohexyl group, or a C6-C20 aliphatic hydrocarbon, respectively or simultaneously.

Hereinafter, the present invention will be described in detail.

The present invention relates to a constant velocity joint grease composition having long-term durability and low friction for extending the service life of an automobile while maintaining physical properties such as extreme pressure and abrasion resistance that are equivalent to those of the prior art.

Looking at the grease composition for automobile constant velocity joint according to the present invention in more detail.

The base oil is a refined mineral oil, using a base oil selected from purified paraffinic mineral oil and naphthenic mineral oil having a kinematic viscosity of 8 to 25 cSt at 100 ℃, 90 to 250 cSt at 40 ℃, preferably 100 ℃ It is preferable to use a base oil having a kinematic viscosity at 10 to 20 cSt and a kinematic viscosity at 40 ° C. to 110 to 190 cSt.

The thickener used for improving durability uses a urea thickener represented by Chemical Formula 1. The urea thickener may be prepared by reacting 1 equivalent of diisocyanate with 2 equivalents of alkyl, cyclo or arylamine in the presence of a lubricant base oil. In this case, it is preferable to use 4,4-methylenebis (phenylisocyanate) as the diisocyanate, and as the amine, an aromatic amine or cyclohexylamine having 6 to 7 carbon atoms, or an aliphatic amine having 6 to 20 carbon atoms is used. It is preferable.

The use amount of the urea-based thickener is 5 to 25% by weight based on the total composition, when the amount is less than 5% by weight, the LED is thin and there is a problem that durability is poor, when it exceeds 25% by weight is led and lubricity And low temperature deteriorates.

The present invention uses molybdenum dialkyldithiocarbamate, vegetable oil-modified molybdenum antiwear agent, zinc dialkyldithiophosphate, calcium sulfonate, amide wax as an additive component for improving physical properties, in particular, preventing abrasion and reducing friction. do.

The molybdenum dialkyldithiocarbamate is 1.0 to 10.0% by weight, the vegetable oil-modified molybdenum anti-wear agent is 0.2 to 5.0% by weight, zinc dialkyldithiophosphate 0.5 to 5% by weight, calcium sulfonate 1.0 to 10.0% by weight and amide 0.1 to 5.0% by weight of the system wax is used.

Grease for automobile constant velocity joints manufactured as described above has an SRV friction coefficient of 0.01 to 0.07 (ASTM D 5707), abrasion wear of 50 µm or less (load 43 kgf · m, rotation speed 570 rpm, joint angle 5 degrees, 3 hours). ), Roll stability (ASTM D 1831) is from +10 to +50, and miscibility stability (ASTM D 217) ranges from +10 to +60, while maintaining physical properties such as extreme pressure and abrasion resistance that are equivalent to those of the prior art. Long-term durability and low friction are improved, which is excellent for extending the life of the car.

Hereinafter, the present invention will be described in detail through the following examples, but the present invention is not limited thereto.

Example 1

1 mole of 4,4-methylenebis (phenylisocyanate), 1.2 mole of cycloamine and 0.8 mole of stearylamine were reacted at 1400 g of base oil having 8 to 12 cSt at 100 ° C., and an additive was added to uniformly disperse the grease. .

Example 2

1 mole of 4,4-methylenebis (phenylisocyanate), 0.8 mole of cycloamine, and 1.2 mole of stearylamine were reacted at 1400 g of base oil having 8 to 12 cSt at 100 ° C., and an additive was added to uniformly disperse the grease. .

Example 3

1 mole of 4,4-methylenebis (phenylisocyanate), 0.8 mole of cycloamine, and 1.2 mole of stearylamine were reacted at 1400 g of base oil having 10 to 20 cSt at 100 ° C., and an additive was added to uniformly disperse the grease. .

Example 4

1 mole of 4,4-methylenebis (phenylisocyanate), 1.0 mole of cycloamine, 0.6 mole of stearylamine, and 0.4 mole of octylamine were reacted at 1400 g of base oil having 8 to 12 cSt at 100 ° C., whereby an additive was added and uniformly dispersed. To prepare grease.

The compositions of the greases of Examples 1 to 4 are briefly summarized in Table 1 below.

Classification (% by weight) Example 1 Example 2 Example 3 Example 4 Base oil Mineral oil 78 82 76 80 Viscosity (100 ° C. CSt) 10 10 17 10 Urea-based thickener 10.7 10.0 9.7 8.0 Ester oil 2.0 2.0 5.0 5.0 Diphenylamine 1.0 0.5 1.0 1.0 Calcium salt 0.5 0.5 0.5 0.5 Molybdenum dialkyldithiocarbamate 2.0 2.5 2.5 2.0 Zinc Dialkyl Dithio Phosphate 1.5 2.0 1.5 2.5 Calcium Sulfonate 2.0 - 2.0 1.0 Amide Wax 1.0 1.0 1.0 0.5 Molybdenum sulfide 0.5 - 1.0 0.5 Vegetable oil modified molybdenum - - 1.5 1.5 Molybdenum Complex 1.0 - 2,5-dimercapto-1,3,4-thiadiazole compound 0.5 -

Experimental Example 1

In order to compare the shear stability of the greases prepared in Examples 1 to 4, miscibility was performed.

The miscibility test is performed according to the method of ASTM D 217, which is a test for measuring the degree of grease dilution according to mechanical use for a long time. It is a test to measure the lead at 25 ℃. The smaller the difference, the better the stability of the mixing, that is, the shear stability.

division Example 1 Example 2 Example 1 Example 2 Mixed war 310 305 320 320 Miscibility 360 370 390 380

Experimental Example 2

Roll stability was performed to measure the shear stability of the greases prepared in Examples 1 to 4.

The shear stability test was carried out according to ASTM D 1831, the roll stability was filled with about 50 g of the sample in the cylinder and operated for 2 hours at 165 rpm at room temperature and then measured the lead. Specifically, it shows the degree of dilution of grease that lubricates when two objects come into contact with each other. The smaller the difference, the better the roll stability, that is, the mechanical shear stability.

division Example 1 Example 2 Example 1 Example 2 Pretest 310 305 320 320 Led after test 340 340 355 350

Experimental Example 3

SRV test was performed to measure the friction coefficient of the greases prepared in Examples 1 to 4.

The SRV Test is performed in ASTM D 5707. The test conditions are measured at 50 Hz, Stroke 1.0 mm, 200 N load, 200 N, temperature 80 ° C., and 60 minutes of time. do.

division Example 1 Example 2 Example 1 Example 2 Coefficient of friction 0.065 0.060 0.050 0.055

Experimental Example 4

In order to measure the generated axial force (Generated Axial Force) of the grease prepared in Examples 1 to 4 was carried out through a simulator tester. The condition of the simulator tester is load torque 300 Nm, rotational speed 150 rpm, joint angle 6 °, 9 °, 12 °, and measurement time is measured for 5 minutes and the average value is obtained.

As a result, it was confirmed that the axial force was excellent when using the grease for the constant velocity joint.

Experimental Example 5

Abrasion tests were carried out to measure the amount of wear of the greases prepared in Examples 1 to 4 above. The test conditions were 43 kgf · m load, rotation speed is 570 rpm, joint angle is 5 °, time is measured for three hours after the wear amount is measured.

As a result, it was confirmed that the wear amount was 50 µm or less.

As described above, the present invention has developed a constant velocity joint grease excellent in durability and low friction as well as improving the extreme pressure and wear resistance of the conventional constant velocity joint by using a urea thickener having excellent durability and low friction. .

Claims (4)

1) a base oil selected from paraffinic mineral oil and naphthenic mineral oil, 2) a urea-based grease thickener represented by the following formula (1), 3) molybdenum dialkyldithiocarbamate, 4) vegetable oil modified molybdenum anti-wear agent, 5) zincdialkyldithiophosphate, 6) calcium sulfonate, 7) amide wax 8) diphenylamine, and 9) Grease composition for automobile constant velocity joints comprising calcium salt: [Formula 1]

In said Formula (1), R <_1> and R <_2> represents a C6-C7 aromatic hydrocarbon, a cyclohexyl group, or a C6-C20 aliphatic hydrocarbon, respectively or simultaneously. According to claim 1, based on the total weight of the grease composition 1) based on the base oil, 2) 5 to 25% by weight of urea grease thickener, 3) 1.0 to 10.0% by weight of molybdenum dialkyldithiocarbamate, 4) vegetable oil Modified Molybdenum Abrasion Resistant 0.2 to 5.0 wt%, 5) Zinc Dialkyldithiophosphate 0.5 to 5 wt%, 6) Calcium Sulfonate 1.0 to 10.0 wt%, 7) Amide Wax 0.1 to 5.0 wt%, 8) Diphenyl A grease composition for automobile constant velocity joints comprising 0.1 to 3.0% by weight of amine and 9 to 10% by weight of calcium salt. The grease composition according to claim 1, wherein the base oil has a kinematic viscosity of 8 to 25 cSt at 100 ° C and a kinematic viscosity of 90 to 250 cSt at 40 ° C, respectively. The frictional coefficient of SRV is 0.01 to 0.07 (ASTM D 5707), the wear amount is 50 µm or less (load 43 kgf · m, rotation speed 570 rpm, joint angle 5 degrees, 3 hours), roll stability ( ASTM D 1831) is +10 ~ +50, and the miscibility stability (ASTM D 217) is +10 ~ +60 grease composition, characterized in that.