KR101953265B1 - Rubber composite for bearing seal - Google Patents

Abstract

An object of the present invention is to provide a rubber composition for bearing seals, which is excellent in low temperature and capable of improving nis sealing properties. Accordingly, the rubber composition for bearing seals according to a preferred embodiment of the present invention is a nitrile butadiene rubber (NBR). , Nitrile Butadiene Rubber), a nitrile content of 18 to 23 parts by weight, an inorganic filler having a particle size of 1 to 5 μm, 20 to 60 parts by weight relative to 100 parts by weight of the polymer, and 100 parts by weight of the polymer Organic filler having from 30 to 70 parts by weight.

Description

Rubber composition for bearing seals {Rubber composite for bearing seal}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition for bearing seals, and more particularly, to a rubber composition for bearing seals which improves the low temperature of a bearing seal used in a vehicle or the like.

A bearing is a device that transmits or moves a force in various types of movements such as rotation, reciprocation, side pressure, angular swing operation by using self-lubricating property or sliding property of a vibrating body under a load and power of a vehicle.

An example of the bearing may include an inner ring, an outer ring, and a plurality of balls. In this case, the inner ring is engaged to move integrally with the rod. The outer ring is fixed to a frame that is radially opposed to the inner ring. A plurality of balls are inserted in the circumferential direction so as to make a rolling contact between the inner ring and the outer ring. Through this, a bearing supports the rod by allowing relative movement between the outer ring and the inner ring by the rolling contact of the ball.

The bearing includes a bearing seal. The bearing seal functions to prevent oil leakage, external dust intrusion, and the rod lubricating surface.

Lubricating oil is filled between the outer ring and the inner ring so that the rolling resistance of the ball is minimized, and a bearing seal is installed to seal the oil to prevent leakage of the lubricant and foreign matters into the lubricant. That is, the bearing seal serves to prevent external dust and needle intrusion, and to protect the rod lubrication surface.

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

In general, the damage of the bearing for the vehicle is due to the poor lubrication between the rolling element and the track during the service life, most of which is caused by the sealing problem of the bearing seal (Bearing Seal). The low temperature, heat resistance and durability standards of bearing seals are becoming more demanding. In order to solve this problem, the Republic of Korea Patent Publication No. 10-2012-0040845 (Patent Document 1) and the like has been known a technique for improving the heat resistance, but the development is poor for the technology having excellent durability in low temperature environment. In particular, recently, as a car is operating in an extreme region, a problem of water leakage occurs even under a low temperature environment of -40 ° C or less, and thus it is necessary to secure sealing property.

Republic of Korea Patent Publication 10-2012-0040845

The present invention has been made to solve various problems including the above problems, and an object of the present invention is to provide a rubber composition for bearing seals that is excellent in low temperature and capable of improving nisu sealing property.

Therefore, the rubber composition for bearing seals according to the preferred embodiment of the present invention is made of nitrile butadiene rubber (NBR), a polymer having a nitrile content of 18 to 23 parts by weight, and a particle diameter of 0.1 to 10 μm. An inorganic filler having 20 to 60 parts by weight relative to 100 parts by weight of the polymer, and an organic filler having 30 to 70 parts by weight relative to 100 parts by weight of the polymer.

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

In addition, phenylene diamines (Phenylene diamines) and 2,2,4-trimethyl-1,2-dihydrocuinorin (2,2,4-Trimethyl-1,2-dihydroquinoline), containing 100 weight of the polymer It may further include an anti-aging agent having 5 to 10 parts by weight relative to the part.

In addition, zinc oxide and stearic acid may be included, and a crosslinking aid having 7 to 11 parts by weight based on 100 parts by weight of the polymer may be further included.

In addition, it is made of a diester-based, and may further include a plasticizer having 10 to 20 parts by weight based on 100 parts by weight of the polymer.

According to the present invention, low temperature was secured by changing the content of the raw material rubber nitrile, and nitricity was secured in a low temperature environment by controlling the particle diameter of the inorganic filler.

EMBODIMENT OF THE INVENTION Hereinafter, the preferable Example of the rubber composition of the bearing seal of this invention is described in detail.

As described above, the bearing transmits or moves the force in various movement forms such as rotation, reciprocation, side pressure, angular swing operation by using the self-lubricating property or the sliding property of the vibrating body under the load and power of the vehicle. It is a device, the bearing seal is included in the bearing, and serves to prevent oil leakage, external dust intrusion, rod lubrication surface.

A rubber composition for bearing seals according to a preferred embodiment of the present invention comprises a polymer, a filler, an anti-aging agent, a plasticizer, and a crosslinking agent.

The polymer consists of nitrile butadiene rubber (NBR). The nitrile butadiene rubber has good oil resistance, abrasion resistance, and aging resistance, and functions to prevent leakage of oil, intrusion of external dust, and protection of the lubricating surface of the rod.

In this case, the nitrile content has 18 to 23 parts by weight relative to 100 parts by weight of the polymer. Nitrile content in conventional nitrile butadiene rubbers typically has more than 28 wt%. By the way, the content of nitrile of 28 wt% or more may not ensure low temperature at a low temperature of −40 ° C. or lower. Therefore, in the present invention, by lowering the nitrile content to 18wt% to 23wt% by weight, it can have excellent low temperature at a low temperature of -40 ℃ or less.

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

Fillers are intended to improve the adhesion of the polymer while improving processability and reinforcement. Fillers in the present invention include organic fillers and inorganic fillers. The organic filler has 30 to 70 parts by weight relative to 100 parts by weight of the polymer. The organic filler improves mechanical properties. In this case, when the organic filler is more than 70 parts by weight, the mechanical properties are too high, resulting in a large rotation torque of the bearing.

The inorganic filler has 20 to 60 parts by weight relative to 100 parts by weight of the polymer. The inorganic filler is mixed with the organic filler to control the mechanical properties of the rubber. In addition, in this case, the inorganic filler prevents wear resistance deterioration caused by the low nitrile content of the polymer, and prevents or minimizes the infiltration of nisu.

To this end, the inorganic filler preferably has a particle diameter of 0.1 ㎛ to 10 ㎛. When the particle diameter of the inorganic filler exceeds 10 µm, the number of nibs is generated through the voids when the rubber is worn, but the number of the seals is deteriorated as the voids become wider. When the inorganic filler is less than 0.1 μm, there is a problem that the mechanical properties are weakened, the sealing property is lowered, and the torque is increased.

This is because when the wear due to the contact with the counterpart, the voids are formed as the size of the filler and the number of the water generated in the space, the inorganic filler provided in the present invention by adjusting the particle diameter of 0.1 to 10 ㎛, it is possible to prevent the infiltration At the same time, the sealing property can be improved.

The inorganic filler includes talc based, titanium based and silica based. The inorganic filler is a synthetic silica (Synthetic amorphous silica), hydrous silica (hydrous silica), calcium carbonate (activate colloidal calcium carbonate), kaolinite (Hydrated aluminum silicate, kaolin), diatomite (diatomite), titanium dioxide (titanium dioxide), It may be made of at least one of wollastonite and hydrous silica magnesium silicate.
The crosslinking agent functions to crosslink the monomers constituting the polymer when the kneaded rubber is heated to an appropriate temperature. The crosslinking agent may apply 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.

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Antioxidants serve to prevent aging of organic polymeric materials. Antioxidants are also called antioxidants because they often have the same effect as antioxidants. Antioxidants act to stop the chain reaction, which is automatically oxidized by oxygen, a major factor in aging.

In the present invention, it may be composed of phenylene diamines and 2,2,4-trimethyl-1,2-dihydrocuinoline (2,2,4-Trimethyl-1,2-dihydroquinoline) as an anti-aging agent. In this case, the anti-aging agent preferably has 5 to 10 parts by weight based on 100 parts by weight of the polymer.

Crosslinking aids are intended to increase the crosslinking speed of the polymer while preventing side chain reactions to increase the crosslinking density. The crosslinking aid may include zinc oxide and stearic acid. In addition, the crosslinking aid may include a silane coupling additive (Silane Coupling Agent).

In this case, the silane coupling additive means that one end has an organic functional group (Organic Functional Group) and the other has a methoxy group or an ethoxy group. Silane is basically polymerized by condensation reaction with water at room temperature. The ethoxy group at one end is hydrolyzed by water and ethanol is dropped and becomes Si-OH group. The Si-OH group is unstable to bond with Si-O-Si, which is a Siloxane bond, and the silane is crosslinked and gelated. The content of the crosslinking aid may have 7 to 11 parts by weight based on 100 parts by weight of the polymer.

Plasticizers serve to soften the polymer. For example, the plasticizer is a simple description of a long string of string-like molecules, the harder the pull between each other. In this case, when the plasticizer is inserted between the molecules, the direct pulling force between the plastic molecules is weakened, which causes the plastic to bend well. It is therefore advantageous for the plasticizer to be well mixed, i.e., blendable, with the polymer.

In the present invention, the plasticizer is made of diester, 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 (hereinafter, referred to as "example" for convenience) according to the embodiment of the present invention as described above, the rubber composition of the conventional bearing seal (hereinafter referred to as "comparative example" for convenience) various By testing and comparing with each other, the above effects are explained more clearly.

Table 1 is a table comparing the components of the Examples and Comparative Examples applied to the various tests.

Ingredients (parts by weight) Comparative example Example Polymer
NBR ¹⁾ 100 0 NBR ²⁾ 0 100 Anti-aging 3C ³⁾ 3 3 TMQ ⁴⁾ 4 4 Crosslinking aid ZnO ⁵⁾ 10 10 Stearic Acid ⁶⁾ One One Crosslinking agent Sulfur ⁷⁾ 0.6 0.6 Filler N550 ⁸⁾ 40 40 Graphite 20 20 Inorganic Filler 50㎛ 10 0 Inorganic Filler 3㎛ 0 30 Plasticizer Diester 5 10 1) NBR: Nitrile 33% NBR, Lanxess
2) NBR: Nitrile 20% NBR, Lanxess
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., Ltd.

Table 2 is a table showing the basic physical properties test, low temperature test and low temperature durability test results, the hardness of the above Examples and Comparative Examples, 100% modulus, tensile strength, elongation, low temperature and low temperature durability comparison.

In this case, in the low temperature recovery test, the deformation recovery property in the low temperature range was tested, and the TR-10 cold resistance test was performed. TR-10 refers to a test for measuring the temperature at which 10% recovery of 50% of the strain applied in advance and satisfies the specification of ASTM D1329.

In addition, the basic physical property test satisfies the standard of ASTM D471, respectively.

The basic physical properties showed that both the comparative example and the example satisfied the reference values. That is, the hardness is the same as 78 Shore A, 100% modulus is 69 Kgf / cm ² Example It appeared higher than the comparative example. On the other hand, the tensile strength and elongation, but the comparative example is superior to the example, the difference was not large.

On the other hand, in the low temperature recovery test, it can be seen that the Example recovers at a temperature lower than -47 ° C and -27 ° C of the comparative example when recovering 10%. Through this, it can be seen that the Example has a higher recovery rate than the comparative example even at a lower temperature.

In addition, in the case of low temperature endurance test, the Example was passed in the cycle durability performance, but in the Comparative Example was rejected.

Item Comparative example Example Related Standard Basic property % Elongation 284 221 ASTM D471 Shore A 78 78 Tensile strength (kgf / cm ² ) 198 144 100% Modulus (kgf / cm ² ) 58 69 Low temperature TR-10 (℃) -27 -47 ASTM D1329 Low temperature endurance Cycle durability fail pass

As described above, although described with reference to the preferred embodiment of the present invention, those skilled in the art various modifications and variations of the present invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Claims (5)

A polymer composed of nitrile butadiene rubber (NBR) and having a nitrile content of 18 wt% to 23 wt%;
An inorganic filler having a particle diameter of 0.1 to 5 µm, 20 to 60 parts by weight with respect to 100 parts by weight of the polymer, and at least one of talc and titanium;
Carbon black having 40 parts by weight relative to 100 parts by weight of the polymer; And
Graphite filler having 20 parts by weight relative to 100 parts by weight of the polymer;
Rubber composition for a bearing seal, characterized in that comprising a. delete The method of claim 1,
Phenylene diamines and 2,2,4-trimethyl-1,2-dihydrocuinoline (2,2,4-Trimethyl-1,2-dihydroquinoline), containing 100 parts by weight of the polymer Rubber composition for a bearing seal, characterized in that it further comprises an anti-aging agent having from 5 to 10 parts by weight. The method of claim 1,
Zinc oxide, stearic acid (Stearic Acid), and the rubber composition for a bearing seal, characterized in that it further comprises a crosslinking aid having 7 to 11 parts by weight based on 100 parts by weight of the polymer. The method of claim 1,
It is made of a diester system, the rubber composition for a bearing seal, characterized in that it further comprises a plasticizer having 10 to 20 parts by weight based on 100 parts by weight of the polymer.