KR20180111085A - Rubber composite for bearing seal - Google Patents

Abstract

An object of the present invention is to provide a rubber composition for a bearing seal which is excellent in low temperature and can improve sealing properties of Nishi water. Therefore, the rubber composition for the bearing seal according to the preferred embodiment of the present invention comprises: a polymer composed of nitrile butadiene rubber (NBR) having a nitrile content of 18 to 23 parts by weight; an inorganic filler having a particle diameter of 1 to 5 μm and 20 to 60 parts by weight based on 100 parts by weight of the polymer; and an organic filler having 30 to 70 parts by weight based on 100 parts by weight of the polymer.

Description

Technical Field [0001] The present invention relates to a rubber composition for a bearing seal,

The present invention relates to a rubber composition for a bearing seal, and more particularly, to a rubber composition for a bearing seal that improves the low temperature of a bearing seal used in a vehicle or the like.

The bearing is a device that transmits or moves the force in various forms of motion such as rotation, reciprocating, side pressure, and angular oscillation operation by utilizing the slipperiness of the vibrating body or self-lubricating under the load and power of the vehicle.

Examples of the bearing include an inner ring, an outer ring, and a plurality of balls. In this case, the inner ring is coupled to move integrally with the rod. And the outer ring is fixed to the frame which faces the inner ring in the radial direction. A plurality of balls are inserted in the circumferential direction so as to be in rolling contact between the inner and outer rings. Through this, the bearing supports the rod by allowing the ball to make a relative motion between the outer ring and the inner ring by rolling contact of the ball.

The bearing includes a bearing seal. The bearing seal functions to prevent leakage of oil, prevent external dust penetration, and protect the load lubrication surface.

A bearing seal is provided between the outer ring and the inner ring to fill the lubricating oil so that the rolling resistance of the ball is minimized and to seal the lubricating oil and to prevent foreign matter from entering the lubricating oil. In other words, the bearing seal protects against external dust and Nishikawa intrusion, and the lubrication surface of the rod.

Normally, the bearing seal mainly uses nitrile butadiene rubber (NBR).

Generally, the damage of the vehicle bearing is caused by the defective lubrication between the rolling elements and the track during use, and most of the defective lubrication is caused by the sealing property of the bearing seals. The standards of low temperature resistance, heat resistance and durability of bearing seals are becoming more demanding. In order to solve such a problem, Korean Patent Laid-Open Publication No. 10-2012-0040845 (Patent Document 1) discloses a technique for improving the heat resistance. However, development of a technique having excellent durability in a low temperature environment is poor. Especially in recent years, as the automobile is operated in an extreme region, the problem of Nishi water occurs even under a low temperature environment of -40 ° C or less, and it is necessary to secure the sealing property.

Korean Patent Publication No. 10-2012-0040845

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a rubber composition for a bearing seal which is excellent in low temperature and can improve sealing performance.

Accordingly, the rubber composition for a bearing seal according to a preferred embodiment of the present invention comprises a polymer composed of NBR (Nitrile Butadiene Rubber) having a nitrile content of 18 to 23 parts by weight and a rubber composition having a particle diameter of 0.1 to 10 탆, An inorganic filler having 20 to 60 parts by weight based on 100 parts by weight of the polymer, and an organic filler having 30 to 70 parts by weight based on 100 parts by weight of the polymer.

In this case, the inorganic filler may include talc, titanium, and silica.

Also included are Phenylene diamines and 2,2,4-Trimethyl-1,2-dihydroquinoline, wherein 100 weight percent of the polymer And 5 to 10 parts by weight based on 100 parts by weight of the antioxidant.

Also, it may further include a crosslinking aid having 7 to 11 parts by weight based on 100 parts by weight of the polymer, including zinc oxide (Zinc oxide) and stearic acid (Stearic Acid).

Further, it may further include a plasticizer having a diester system and having 10 to 20 parts by weight based on 100 parts by weight of the polymer.

According to the present invention, the low temperature property is secured by changing the content of the raw rubber nitrile, and the kneading property of the inorganic filler is controlled by controlling the particle size of the inorganic filler.

Hereinafter, a preferred embodiment of the rubber composition of the bearing seal of the present invention will be described in detail.

As described above, a bearing is a bearing that transmits or receives a force in various forms of motion, such as rotation, reciprocating, side pressure, and angular oscillation, And the bearing seal is included in the bearing and functions to prevent leakage of oil, prevention of intrusion of external dust, and protection of the lubrication surface of the rod.

The rubber composition for a bearing seal according to a preferred embodiment of the present invention comprises a polymer, a filler, an antioxidant, a plasticizer, and a cross-linking agent.

The polymer is made of nitrile butadiene rubber (NBR). The nitrile-butadiene rubber is excellent in oil resistance, abrasion resistance and aging resistance, and functions to prevent leakage of oil, to prevent entry of dust outside, and to protect the lubrication surface of the rod.

In this case, the nitrile content is 18 to 23 parts by weight based on 100 parts by weight of the polymer. The nitrile content in the conventional nitrile-butadiene rubber typically has 28 wt% or more. However, with the content of the nitrile of 28 wt% or more, low temperature can not be secured at a low temperature of -40 캜 or lower. Therefore, in the case of the present invention, by lowering the nitrile content to 18 wt% to 23 wt% by weight, excellent low temperature can be obtained at a low temperature of -40 ° C or lower.

On the other hand, as the nitrile content of the polymer becomes 18 wt% to 23 wt%, the abrasion resistance may deteriorate. In order to solve this problem, the present invention uses an organic filler and a filler having an inorganic filler with a small particle diameter.

The filler is intended to improve the adhesiveness of the polymer while improving workability and reinforcement. In the present invention, the filler includes an organic filler and an inorganic filler. The organic filler has 30 to 70 parts by weight based on 100 parts by weight of the polymer. The organic filler improves mechanical properties. In this case, when the amount of the organic filler is more than 70 parts by weight, the mechanical properties become too high, resulting in a large torque of the bearing.

The inorganic filler has 20 to 60 parts by weight based on 100 parts by weight of the polymer. The inorganic filler can be mixed with the organic filler to control the mechanical properties of the rubber. In this case, the inorganic filler prevents deterioration of abrasion resistance caused by lowering the nitrile content of the polymer, and prevents or minimizes the intrusion of Nishikawa.

For this purpose, it is preferable that the inorganic filler has a particle diameter of 0.1 탆 to 10 탆. When the particle size of the inorganic filler exceeds 10 占 퐉, kneading occurs through the voids at the time of abrasion of the rubber, and the void becomes wider, thereby deteriorating the sealing performance of the nipple. When the inorganic filler is less than 0.1 탆, the mechanical properties are excessively high and the sealing property is deteriorated and the torque is increased.

This is because voids are generated in the space by the size of the filler when the abrasion occurs due to contact with the mating part, so that the inorganic filler provided in the present invention can prevent intrusion of Nishikawa by adjusting the particle diameter to 0.1 to 10 mu m And at the same time, the sealing property can be improved.

The inorganic filler includes talc, titanium, and silica. The inorganic filler may be selected from the group consisting of synthetic amorphous silica, hydrous silica, activated colloidal calcium carbonate, hydrated aluminum silicate, kaolin, diatomite, titanium dioxide, And may be made of at least one material selected from wallatinite and hydrous silica magnesium silicate.

The crosslinking agent functions to cross-link the monomers constituting the polymer when the kneaded rubber is heated to an appropriate temperature. The crosslinking agent may be sulfur. In this case, the content of the crosslinking agent may be 0.5 to 2 parts by weight based on 100 parts by weight of the polymer.

Antioxidants prevent aging of organic polymeric materials. Antioxidants are often referred to as antioxidants because they often have the same action as antioxidants. Antioxidants act to stop the chain reaction, which is autoxidized by oxygen, a major factor in the aging process.

In the present invention, antioxidants may be composed of phenyl diamines and 2,2,4-trimethyl-1,2-dihydroquinoline. In this case, the antioxidant preferably has 5 to 10 parts by weight based on 100 parts by weight of the polymer.

The crosslinking aids are intended to increase the crosslinking speed of the polymer while preventing side chain reactions to increase the crosslinking density. As the crosslinking aid, zinc oxide (Zinc oxide), stearic acid (Stearic Acid) may be included. In addition, the crosslinking aids may include a silane coupling agent.

In this case, the silane coupling additive means an organic functional group at one end and a methoxy group or ethoxy group at the other end. Silane is basically polymerized by causing condensation reaction at room temperature by water. The ethoxy group at one end is hydrolyzed by water to lower the ethanol and become the Si-OH group. This Si-OH group becomes unstable and bonds with the siloxane bond Si-O-Si, and the silane is crosslinked to gel. The content of the crosslinking aid may be 7 to 11 parts by weight based on 100 parts by weight of the polymer.

The plasticizer serves to soften the polymer. For example, the action of a plasticizer is briefly explained as follows. Plastics are formed by gathering molecules such as long strings. The stronger the attraction force between molecules becomes, the harder it becomes. In this case, when a plasticizer intercalates between molecules, the direct pulling force between the plastic molecules weakens and bends well. Therefore, it is advantageous that the plasticizer has a property of mixing well with the polymer, that is, a blendability.

In the present invention, it is a diester based plasticizer and may have 10 to 20 parts by weight based on 100 parts by weight of the polymer.

Hereinafter, the properties of the rubber composition according to the embodiment of the present invention (hereinafter referred to as " the embodiment " for the sake of convenience) will be referred to as the rubber composition of the conventional bearing seal By testing and comparing them, the above effect will be explained more clearly.

Table 1 shows the comparison between the constituent components of Examples and Comparative Examples applied to the various tests.

Components (parts by weight) Comparative Example Example Polymer
NBR ¹⁾ 100 0 NBR ²⁾ 0 100 Antioxidant 3C ³⁾ 3 3 TMQ ⁴⁾ 4 4 Crosslinking auxiliary ZnO ⁵⁾ 10 10 Stearic Acid ⁶⁾ One One Cross-linking agent Sulfur ⁷⁾ 0.6 0.6 Filler N550 ⁸⁾ 40 40 Graphite 20 20 Inorganic filler 50 탆 10 0 Inorganic filler 3 ㎛ 0 30 Plasticizer Diester 5 10 1) NBR: Nitrile 33% NBR, Lenxess
2) NBR: Nitrile 20% NBR, Lenxess
3) 3C: Phenylene diamines, Kumho Petrochemical
4) TMQ: 2,2,4-Trimethyl-1,2-dihydroquinoline, FLEXSYS
5) ZnO: Zinc oxide, SBC
6) Stearic Acid: Stearic acid, NATOLEO
7) Sulfur: Hwang, Miwon Corporation
8) N550: FEF, DONGYANG STEEL CHEMICAL CO.

Table 2 shows the hardness, 100% modulus, tensile strength, elongation, low temperature and low temperature durability of the above Examples and Comparative Examples as a result of the basic physical property test, the low temperature property test and the low temperature endurance test.

In this case, the low-temperature recovery test was conducted to test the resistance to deformation recovery in the low-temperature region, and the cold resistance test of TR-10 was conducted. TR-10 is a test for measuring the temperature at which 50% of deformation was restored 10% beforehand, and satisfied the standard of ASTM D1329.

In addition, the basic physical property tests satisfied the specifications of ASTM D471, respectively.

The basic physical properties of the comparative example and the example were found to satisfy the standard values. That is, the hardness is the same as 78 Shore A, and the 100% modulus is 69 Kgf / cm ² Which is higher than the comparative example. On the other hand, the tensile strength and elongation were superior to those of the comparative example, but the difference was not large.

On the other hand, in the low-temperature recovery test, it can be seen that the temperature at the time of recovery of 10% in the example is recovered at -47 캜 and at a lower temperature of -27 캜 in the comparative example. As a result, it can be seen that the recovery rate of the Examples is lower than that of Comparative Example even at a lower temperature.

In the case of the low-temperature endurance test, the examples were judged to be acceptable in the cycle endurance performance, while the comparative examples were rejected.

Item Comparative Example Example Related Standards Basic Properties Elongation (%) 284 221 ASTM D471 Hardness (Shore A) 78 78 Tensile strength (kgf / cm ² ) 198 144 100% Modulus (kgf / cm ² ) 58 69 Low temperature TR-10 (占 폚) -27 -47 ASTM D1329 Low temperature endurance Cycle duration fail pass

Although the present invention has been described with reference to the preferred embodiments thereof, 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 and scope of the invention as defined in the following claims. It can be understood that

Claims (5)

A polymer consisting of nitrile butadiene rubber (NBR) having a nitrile content of 18 wt% to 23 wt%;
An inorganic filler having a particle diameter of 1 to 5 占 퐉 and 20 to 60 parts by weight based on 100 parts by weight of the polymer; And
An organic filler having 30 to 70 parts by weight based on 100 parts by weight of the polymer;
And a rubber composition for a bearing seal. The method according to claim 1,
Wherein the inorganic filler comprises talc, titanium, and silica. The method according to claim 1,
Phenylene diamines and 2,2,4-trimethyl-1,2-dihydroquinoline are contained in 100 parts by weight of the polymer. Wherein the antioxidant further comprises 5 to 10 parts by weight of the antioxidant. The method according to claim 1,
Wherein the rubber composition further comprises a crosslinking aid having 7 to 11 parts by weight based on 100 parts by weight of the polymer, the composition including zinc oxide (Zinc oxide) and stearic acid (Stearic Acid). The method according to claim 1,
Diester based on 100 parts by weight of the polymer, and a plasticizer having 10 to 20 parts by weight based on 100 parts by weight of the polymer.