KR101605797B1 - Rubber Composition of Oil Seal for Power steering System - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary oil seal composition for a power steering apparatus and a rotary oil seal for a power steering apparatus manufactured using the same. The rotating oil seal composition of the power steering apparatus comprises 100 parts by weight of hydrogenated acrylonitrile-butadiene rubber; 40 to 60 parts by weight of FEF carbon black; 10 to 30 parts by weight of SRF carbon black; And 4 to 8 parts by weight of a crosslinking agent. According to the oil seal composition for rotation of the power steering apparatus of the present invention and the oil seal for rotation of the power steering apparatus manufactured using the oil seal composition of the present invention, it is possible to prevent the occurrence of friction joints even in long-term use while maintaining the heat resistance, oil resistance, . The use of the oil seal composition for rotation of the power steering apparatus of the present invention reduces the modulus, thereby lowering the force (tightening force) by which the oil seal presses the shaft and also reducing the surface smoothness so that oil or grease remains on the surface of the material To prevent the dry friction between the seal and the shaft, thereby preventing occurrence of frictional engagement even during long-term use.

Power steering, rotary, oil seal, composition, carbon black, FEF, SRF

Description

Technical Field [0001] The present invention relates to an oil seal composition for a power steering apparatus,

The present invention relates to a rotary oil seal composition for a power steering apparatus, and more particularly, to a rotary oil seal composition for a power steering apparatus capable of reducing the tightening force of the oil seal on the shaft and preventing dry friction between the seal and the shaft by reducing the modulus, To an oil seal composition for rotation of a power steering apparatus, and to an oil seal for rotation of a power steering apparatus manufactured using the oil seal composition.

Power Steering Oil Seal is mounted on a steering system that changes the rotational motion to a linear motion by the force of hydraulic pressure when the driver rotates the steering wheel and transfers it to the tire. do. More specifically, a steering gear, that is, a power steering gear (not shown) mounted in a power steering gear, plays a role of controlling the steering force of the driver according to the driving condition, The power steering gear) to the outside of the cylinder tube.

In order to manufacture such a power steering oil seal, carbon black is added to the rubber in order to improve the physical properties of the oil seal including strength and the like. The carbon black to be added for manufacturing the oil seal is FEF carbon black, which is obtained by using FEF carbon black because it can obtain a smooth surface, has excellent physical reinforcing effect and excellent workability (dispersibility).

However, when the FEF carbon black is used, the stiffness and modulus of the seal are excessively high due to the high stiffness and modulus of the seal, so that the lubricant film between the seal and the shaft is broken during operation, thereby generating dry friction, There was a problem.

In order to solve the problems of the prior art as described above, the present invention reduces the tightening force of the seal on the shaft by reducing the modulus while maintaining the heat resistance, oil resistance and low temperature and prevents the friction between the seal and the shaft, And to provide an oil seal composition for rotary use of a power steering apparatus that can prevent the above problems.

Another object of the present invention is to provide a rotary oil seal for a power steering apparatus manufactured using the above composition.

In order to accomplish the above object, the present invention provides a rubber composition comprising 100 parts by weight of a hydrogenated acrylonitrile-butadiene rubber; 40 to 60 parts by weight of FEF carbon black; 10 to 30 parts by weight of SRF carbon black; And 4 to 8 parts by weight of a crosslinking agent.

As the crosslinking agent, an organic peroxide can be used, and a representative example of the organic peroxide is dicumylperoxide.

The FEF carbon black has a particle diameter of 40 to 48 mu m, and the SRF carbon black has a particle diameter of 70 to 90 mu m.

The rotary oil seal composition of the power steering apparatus may further include a crosslinking auxiliary agent. As the crosslinking aid, for example, zinc oxide or stearic acid may be used.

The rotary oil seal composition of the power steering apparatus may further comprise an antioxidant. As the antioxidant, for example, poly-2,2,4-trimethyl-1,2-dihydroquinoline or 2,6-t-butyl-4-methylphenol may be used.

The rotary oil seal composition of the power steering apparatus may further include a plasticizer. As the plasticizer, for example, dioctyl phthalate or dioctyl adipate may be used.

The present invention also provides a rotary oil seal for a power steering apparatus manufactured using the rotary oil seal composition of the power steering apparatus.

According to the oil seal composition for rotation of the power steering apparatus of the present invention and the oil seal for rotation of the power steering apparatus manufactured using the oil seal composition of the present invention, it is possible to prevent the occurrence of friction joints even in long-term use while maintaining the heat resistance, oil resistance, .

The use of the oil seal composition for rotation of the power steering apparatus of the present invention reduces the modulus of the seal to lower the force (tightening force) of the shaft against the shaft and also causes the oil or grease to remain on the surface of the material To prevent the dry friction between the seal and the shaft, thereby preventing occurrence of frictional engagement even during long-term use.

The inventors of the present invention have made efforts to solve such a conventional problem (in order to improve the noise characteristic generated when sliding the seal and the shaft), and as a result, it has been found that a part of the carbon black, FEF, The modulus is reduced by maintaining the heat resistance, oil resistance, and low temperature properties of the material as it is produced by changing to SRF which is larger in particle size, less hysteresis and dynamic characteristic and is mainly used in tire manufacturing, The friction force is not generated by lowering the pressing force of the shaft (tightening force), and since the surface smoothness is lowered and the oil or grease remains on the surface of the material, drying friction between the seal surface and the shaft does not occur, It is confirmed that friction joining does not occur even when used, thereby completing the present invention It was.

Hereinafter, the present invention will be described in more detail. The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary meanings and should be construed in accordance with the technical meanings and concepts of the present invention.

The present invention relates to a hydrogenated acrylonitrile-butadiene rubber resin composition for use in manufacturing a rotary oil seal for use in a power steering system comprising 40 to 60 parts by weight of hydrogenated acrylonitrile-butadiene rubber and FEF carbon black, SRF carbon black 10 to 30 parts by weight reduces the modulus of the conventional oil seal while maintaining the characteristics such as heat resistance, oil resistance and cold resistance of the conventional oil seal, thereby lowering the force (tightening force) . In addition, by lowering the surface smoothness (surface modification, increasing surface roughness), oil or grease is allowed to remain on the surface of the material having increased surface roughness, so that the dry friction between the seal surface and the shaft does not occur, No friction coupling occurs.

As the rubber in the composition of the present invention, a hydrogenated nitrile rubber (H-NBR) excellent in heat resistance and oil resistance is used. Hydrogenated nitrile rubbers have improved heat resistance by hydrogenating double bonds existing in nitrile rubber (NBR), which is excellent in oil resistance. The smaller the acrylonitrile contained in the rubber, the better the low temperature. The higher the content of acrylonitrile, Heat resistance increases.

The carbon black used in the present invention is an FEF carbon black having a particle size of 40 to 48 μm and excellent in reinforcement and surface smoothness, and SRF carbon black having a hysteresis (hysteresis) and a good dynamic characteristic with a particle diameter of 70 to 90 μm Thereby increasing the strength of the rubber, improving the abrasion resistance, and adjusting the modulus of the rubber.

The carbon black preferably contains 40 to 60 parts by weight of FEF carbon black and 10 to 30 parts by weight of SRF carbon black with respect to 100 parts by weight of the hydrogenated acrylonitrile-butadiene rubber.

If the amount of FEF carbon black used exceeds 60 parts by weight, the modulus of the rubber is increased to increase the tightening force of the seal, so that abnormal noise due to interference with the shaft is generated. If the amount is less than 40 parts by weight, there is a high possibility of a leak.

When the amount of the SRF carbon black is less than 10 parts by weight, the surface smoothness modifying effect is deteriorated and the dynamic characteristics and the like are hardly exhibited. When the amount is more than 30 parts by weight, the rubber reinforcing effect is lowered.

The crosslinking agent used in the composition of the present invention is used to make crosslinking between polymer chains when the compounded rubber is heated to an appropriate temperature. Since the rubber composition of the present invention has a substantially saturated polymer structure, organic peroxides are used instead of sulfur as a crosslinking agent.

An example of an organic peroxide that can be used in the present invention is dicumyl peroxide. Unlike sulfur, dicumyl peroxide decomposes at the crosslinking temperature to form free radicals (R.). These free radicals pull hydrogen atoms from the polymer chain (PH) to form RH and form polymer radicals (P.). Adjacent polymer radicals bind to each other to form a carbon-carbon bridge (P-P) between the polymers.

The cross-linking agent is preferably contained in an amount of 4 to 8 parts by weight based on 100 parts by weight of the hydrogenated acrylonitrile-butadiene rubber. If the content of the crosslinking agent exceeds 8 parts by weight, crosslinking will occur. If the amount of the crosslinking agent is less than 4 parts by weight, uncrosslinking will occur, which may cause oil leakage in the power steering oil due to deterioration of physical properties and it is difficult to properly function the power steering apparatus.

The composition of the present invention may contain a certain amount of crosslinking aid to assist the role of the crosslinking agent. The crosslinking aid may be any of those usually used for organic peroxide crosslinking, including, for example, zinc oxide, stearic acid, and the like.

The crosslinking aid may be included in an amount of 1 to 6 parts by weight based on 100 parts by weight of the hydrogenated acrylonitrile-butadiene rubber.

In addition, the rubber composition of the present invention may contain an antioxidant.

The antioxidant is not limited to a specific one, and for example, poly-2,2,4-trimethyl-1,2-dihydroquinoline or 2,6-t-butyl-4-methylphenol can be used.

The hydrogenated acrylonitrile-butadiene rubber resin composition of the present invention may contain the plasticizer in an amount of 3 to 10 parts by weight per 100 parts by weight of the hydrogenated acrylonitrile-butadiene rubber in order to improve cold resistance, flowability and workability of the rubber have. As the plasticizer, dioctyl phthalate or dioctyl adipate can be used. If the amount is less than 3 parts by weight, the effect of improving the cold resistance, flowability and workability of the rubber is insignificant. If the amount is more than 10 parts by weight, An excessive amount of plasticizer can be extracted into the oil, which makes it unsuitable for use in power steering.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be within the scope of the appended claims.

Examples and Comparative Examples

According to the composition and contents in Table 1 below, a rotary oil seal composition for a power steering system was prepared.

1) H-NBR: ZETPOL 1020, Zeon

2) carbon black FEF: N550, particle size 40 to 48 탆,

3) carbon black SRF: N770, particle diameter 70 to 90 탆,

4) DOP: dioctyl phthalate, aekyung emulsification

5) ZnO: zinc oxide, sambo zinc

6) St-acid: Stearic acid, peace keeping industry

7) RD: POLYMERIZED 2,2,4-TRIMETHYL-1,2- DIHYDROQUINOLINE, Peace Drug

8) DCP: dicumyl peroxide, Shin Kwang Chemical

The hardness, the tensile strength, the elongation, the heat resistance, the oil resistance, the long force, the frictional force, and the joint characteristics were measured by the following method and the results are shown in Table 2 below Respectively.

Test Methods

1. Hardness: In accordance with clause 7 of KS M6518

2. Tensile strength: According to 5 of KS M6518

3. Elongation: According to 5 of KS standard KS M6518

4. Heat resistance: According to 8 of KS M6518

5. Oil resistance: According to clause 13 of KS M6518

6. Long force: The force to tighten the jig (shaft outer diameter) of the seal after 15 seconds after the seal is attached to the jig having the same size (outer diameter) as the shaft is measured by a load cell connected to the measuring jig. Read through.

7. Friction test: The static friction coefficient and the coefficient of dynamic friction applied to the specimen when moving 25 mm at a rate of 50 mm / min after applying a load of 100 g

8. Seam characteristics: After the seal is mounted on the shaft, it is measured at a pressure of 6.5 bar and a rotation angle of ± 540 ° at 45 ° C at 80 ° C.

(No lubrication test is conducted without lubricant between the seal and shaft. Grease lubrication test is performed after applying a small amount of grease to the neck portion of the seal.)

As shown in Table 2, it can be seen that the present invention exhibits a low modulus of 50% and a modulus of 100% in a state where the heat resistance and the oil resistance remain the same as in the prior art. This is also directly related to the tightening force of the seal, and it can be seen that the tightening force of the seal of the present invention is lower than that of the prior art. The low tightening force of the seal lowers the friction with the shaft, so no noise is generated during the seal operation. In the evaluation of the occurrence of joints performed in the non-lubricated state, the seals produced by the conventional techniques produced noises in one hour, but the seals produced by the present invention did not generate seams even after 100 hours passed.

In addition, the present invention shows a somewhat higher value of static frictional force and dynamic frictional force than the conventional technique. It is considered that the surface smoothness is somewhat lowered by using the SRF having a slightly larger diameter and reducing the amount of FEF having a good surface smoothness. It is considered that this surface modifying effect (increase in roughness) appears to be advantageous to the occurrence of joint by reducing the contact area because the surface has a rather roughness rather than being too smooth. In addition, it is considered that the increase of the surface roughness will cause the grease or the oil to stay on the surface continuously, thereby delaying the time of occurrence of the dry friction, and it is confirmed that the present invention does not cause the occurrence of the joint even after 150 hours of grease lubrication there was.

Claims (12)

Hydrogenated acrylonitrile-butadiene rubber 100 parts by weight; 40 to 60 parts by weight of FEF carbon black; 10 to 30 parts by weight of SRF carbon black; And 4 to 8 parts by weight of a crosslinking agent, The FEF carbon black has a particle diameter of 40 to 48 탆, Wherein the SRF carbon black has a particle diameter of 70 to 90 占 퐉. The method according to claim 1, Wherein the cross-linking agent is an organic peroxide. 3. The method of claim 2, Wherein the organic peroxide is dicumyl peroxide. ≪ RTI ID = 0.0 > 15. < / RTI > delete delete The method according to claim 1, And a crosslinking auxiliary agent. ≪ Desc / Clms Page number 24 > The method according to claim 6, Wherein the crosslinking aid is zinc oxide or stearic acid. The method according to claim 1, Wherein the lubricating oil composition further comprises an antioxidant. 9. The method of claim 8, Wherein the antioxidant is poly-2,2,4-trimethyl-1,2-dihydroquinoline or 2,6-t-butyl-4-methylphenol. The method according to claim 1, Wherein the lubricating oil composition further comprises a plasticizer. 11. The method of claim 10, Wherein the plasticizer is dioctyl phthalate or dioctyl adipate. A rotary oil seal for a power steering system manufactured using the rotary oil seal composition of the power steering apparatus according to any one of claims 1 to 3 and 6 to 11.