KR20180077347A - Rubber composite for a shock absorber oil seal - Google Patents

Abstract

The present invention provides a rubber composition for a shock absorber sealing member having excellent wear resistance. The rubber composition for the shock absorber sealing member includes a polymer, a filler, a crosslinking agent, an anti-aging agent, a plasticizer and a crosslinking accelerator. The polymer is acrylonitrile-butadiene rubber (NBR), 50-150 parts by weight of the filler are included with respect of 100 parts by weight of the polymer, and the filler includes 5-15 parts by weight of silicon carbide with respect of 100 parts by weight of the polymer.

Description

Technical Field [0001] The present invention relates to a rubber composition for a shock absorber sealing member,

The present invention relates to a rubber composition for a shock absorber sealing member, and more particularly to a rubber composition for a shock absorber sealing member which is installed on a cylinder tube of a shock absorber of a vehicle and prevents oil or gas from flowing out of the cylinder tube. .

Generally, a shock absorber is installed between an axle of a vehicle and a vehicle body, and absorbs vibrations and shocks that the axle receives from the road surface when the vehicle is traveling, thereby improving ride comfort.

The shock absorber roughly includes a cylinder tube and a piston rod. The cylinder tube contains oil or gas. The piston rod moves in and out of the cylinder tube. The piston is installed at an end of the piston rod to move up and down within the cylinder tube.

In the shock absorber, when the spring oscillates due to a difference in the road surface while the vehicle is traveling on an irregular road surface, the piston of the shock absorber is received by the vibration of the spring to move up and down with respect to the cylinder tube. At this time, as the piston moves up and down, oil or gas in the cylinder tube moves up and down through the orifice of the piston valve to apply a resistance pressure to the piston, thereby damping the vibration of the spring.

In order to continuously perform the above action, the shock absorber needs to keep the oil pressure or the gas pressure in the cylinder tube constant. To this end, a sealing member is provided between the cylinder tube and the piston. The sealing member is provided in contact with the piston in a state of being fixed to the cylinder tube so that oil or gas in the cylinder tube is not leaked between the piston and the cylinder tube even if the piston moves up and down with respect to the cylinder tube.

The shock absorber sealing member typically includes a metal reinforcement ring, a spring, and a body portion. In this case, after the main body portion of the rubber material forming the seal lip is integrally formed in the metal reinforcing ring, a spring is inserted so as to apply an appropriate tightening force to the lip portion of the main body portion.

The polymer of the rubber composition constituting the main body usually uses an acrylonitrile rubber composition.

However, it is necessary to maintain durability even in an environment with poor road conditions due to overseas export. When the vehicle is driven in an environment with poor road conditions, the cleanliness in the shock absorber is not good, and the metal chips and foreign matter are invaded into the shock absorber by the penetration of the shock absorber, There is a problem.

Patent Publication No. 10-2011-0051317

SUMMARY OF THE INVENTION It is an object of the present invention to provide a shock absorber sealing member having improved abrasion resistance and scratch resistance and excellent sealing performance.

Accordingly, the present invention provides a rubber composition for a shock absorber sealing member comprising a polymer, a filler, a crosslinking agent, an antioxidant, a plasticizer and a crosslinking aid, wherein the polymer is acrylonitrile-butadiene rubber (NBR) And 50 to 150 parts by weight with respect to 100 parts by weight of the polymer, wherein the filler comprises silicon carbide having 5 to 15 parts by weight with respect to 100 parts by weight of the polymer, and a rubber composition for a shock absorber sealing member .

The nitrile content of the NBR rubber is 18 wt% to 23 wt%.

In addition, the antioxidant may include phenylene diamines having 1 to 5 parts by weight based on 100 parts by weight of the polymer.

The antioxidant may include N-phenyl-N'-isopropyl-P-phenylenediamine and polymerized 2,2,4-trimethyl-1,2-dihydroquinoline resin. can do.

According to the present invention having the above-described constitution, by satisfying the wear resistance and the scratch resistance, the noise of the vehicle can be reduced even in a severe surrounding environment, and the ride comfort and the running stability are excellent

1 is a view showing an example of a shock absorber to which a rubber composition for a sealing member of a shock absorber according to an embodiment of the present invention is applied.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing an example of a typical automotive suspension device.

A vehicle shock absorber 10 includes a cylinder tube 11, a piston rod 12, a piston valve 13, a separation piston 14, a rod guide 12, (16).

The piston rod 12 is inserted into the cylinder tube 11 and the other end extends outwardly through the upper end of the cylinder tube 11.

The piston valve 13 is provided under the piston rod 12 to divide the inside of the cylinder tube 11 into an upper rebound chamber 17a and a lower compression chamber 17b . A flow path 13a for oil flow between the tension chamber 17a and the compression chamber 17b is formed in the body of the piston valve 13. [

The separation piston 14 is located inside the cylinder tube 11 to partition the upper compression chamber 17b and the lower gas chamber 18.

A rod guide 16 is provided for slidingly supporting the piston rod 12 at the upper end of the separating piston 14 and the cylinder tube 11.

The operation of the shock absorber 10 having the above structure is such that when an impact is inputted from the road surface as the vehicle travels, the piston rod 12 reciprocates upward and downward, The oil moves between the upper tension chamber 17a and the lower compression chamber 17b through the formed flow path 13a to generate a damping force to mitigate the input shock.

In this case, the sealing member 100 of the shock absorber is formed between the piston rod 12 and the cylinder tube 11 so as to prevent foreign substances from being introduced from the outside, and to prevent the internal oil from flowing out to the outside. The sealing member 100 of the shock absorber may be formed of a plurality of members or may be integrally formed according to the manufacturer's intention.

The rubber composition for a shock absorber sealing member according to a preferred embodiment of the present invention comprises a polymer, a filler, a crosslinking agent, a plasticizer, and a crosslinking aid.

The polymer includes acrylonitrile butadiene rubber produced by emulsion copolymerization of acrylonitrile and butadiene.

Acrylonitrile-butadiene rubber is also called NBR rubber, which is a terpolymer of acrylonitrile and butadiene. The acrylonitrile-butadiene rubber has different properties depending on the content of acrylonitrile. The higher the content of acrylonitrile, the higher the resistance to oil (oil resistance), but the elasticity of the rubber and the low compression permanent shrinkage deteriorate.

According to the present invention, acrylonitrile butadiene rubber having a nitrile content of 18 to 23% is included. If the nitrile content exceeds 23%, the finished sealing member deteriorates the low-temperature sealing property at -40, and if the nitrile content is less than 18%, the finished sealing member drops the oil resistance to an appropriate level or less.

The plasticizer serves to soften the polymer. In general, the plasticizer is an organic material which is added to a thermoplastic such as vinyl chloride and vinyl acetate to increase the thermoplasticity, thereby facilitating molding at a high temperature, and plays a role similar to a softener which gives flexibility.

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.

According to this embodiment, the plasticizer may be a diester. The diester is a diester type lubricating oil obtained as a reaction product of an organic acid and an alcohol. Suitable diester molecular structures exhibit properties such as high bookstore index, high flash point, low pour point, good lubricity, and the like, as compared to petroleum with similar viscosities.

When a diester is applied, the low temperature property is excellent and the oil resistance is improved.

In this case, the content of the diester is preferably 10 to 30 parts by weight based on 100 parts by weight of the polymer. When the content is less than 10 phr, the low-temperature recovery property deteriorates. When the content exceeds 30 phr, the oil resistance is deteriorated.

The crosslinking agent functions to cross-link the monomers constituting the polymer. The crosslinking agent may include sulfur. In this case, the crosslinking agent may have 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. In this case, as the crosslinking aid, stearic acid and zinc oxide (zinc oxide) may be contained, and the content thereof may be 5 phr to 10 phr.

The filler is intended to improve the adhesiveness of the polymer while improving workability and reinforcement. According to this embodiment, the filler includes FEF, graphite, and silicon carbide powder, and may have 50 to 150 parts by weight based on 100 parts by weight of the polymer.

Silicon carbide (SiC) is a compound produced by the reaction of silicon (Si) with carbon (C), and has properties of high hardness and high strength, and is generally used in bulletproof materials, brake discs, heaters and the like.

According to the present invention, silicon carbide powder is used as a filler of a shock absorber sealing member. Through this, the abrasion resistance can be remarkably improved, and the occurrence of the scratches can be prevented or minimized even if the foreign matter intrudes into the sealing member.

In this case, the silicon carbide powder may occupy 5 to 15 parts by weight per 100 parts by weight of the polymer. This is because when the weight part is smaller than 5 parts by weight, the wear resistance effect deteriorates, and when it is larger than 15 parts by weight, the dispersibility and the elasticity are deteriorated.

The rubber composition for a shock absorber sealing member according to an embodiment of the present invention may further include an anti-aging agent. 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. According to this embodiment, the antioxidant may comprise phenyl diamine.

In this case, as the anti-aging agent, N-phenyl-N'-isopropyl-P-phenylenediamine and polymerized 2,2,4-trimethyl- 1,2-dihydroquinoline resin, and the content thereof is preferably 5 to 10 parts by weight based on 100 parts by weight of the polymer.

The rubber composition according to a preferred embodiment of the present invention improves the low temperature property by including the acrylonitrile-butadiene rubber having a polymer content of 18% to 23%, and improves the abrasion resistance by including silicon carbide as a filler.

As a result, the low temperature property is improved and the durability of the vehicle is also improved due to the harsh environment of the vehicle.

Hereinafter, results of various tests for the properties of the rubber composition according to the embodiment of the present invention (hereinafter, referred to as "Examples for the sake of simplicity") will be described below. Table 1 is a table comparing the constituent components of the examples applied to the various tests.

Components (parts by weight) Comparative Example Example Polymer NBR1 ¹⁾ 100 0 NBR2 ²⁾ 0 100 Filler N550 ³⁾ 80 80 Graphite AO ⁴⁾ 20 20 Silicon carbide 0 10 Antioxidant 3C ⁵⁾ 2 2 CD ⁶⁾ 2 2 TMQ ⁷⁾ 0 2 Crosslinking auxiliary ZnO ⁸⁾ 5 5 Stearic Acid ⁹⁾ 2 2 Cross-linking agent Sulfur ¹⁰⁾ 0.6 0.6 Plasticizer TP-95 ¹¹⁾ 0 20 RS-107 ¹²⁾ 15 0 1) NBR1: acrylonitrile-butadiene having a nitrile content of 23%, JSR Co., Ltd.
2) NBR2: acrylonitrile-butadiene having a nitrile content of 19%, Nippon Zeon Co., Ltd.
3) N550: FEF, DONGYANG STEEL CHEMICAL CO.
4) Graphite AO: - (C) n-, Nippon Electric Carbon Co., Ltd.
5) 3C: N-Phenyl-N'-Isopropyl-P-Phenylendiamine, Kumho Monsanto
6) CD: 4,4'-dimethylbenzyl diphenylamine,
7) TMQ: Polymerized 2,2,4-Trimethyl-1,2-Dihydroquinoline resin, Taian Flying Chemical
8) ZnO: zinc oxide (Zinc oxide), Sambo
9) Stearic Acid: Stearic acid,
10) Sulfur: Hwang, Miwon Corporation
11) TP-95: Diester system, ROHM & HAAS
12) RS-700: Polyether ester, ADK Corp.

Table 2 shows the test results of hardness, 100% modulus, tensile strength, elongation and wear loss ratio, and is a comparative table showing the physical properties of the above Examples and Comparative Examples.

In this case, the basic physical properties satisfy the specification of ASTM D471.

If the, embodiment, as shown in Table 2, the hardness, 100% modulus, and each has a tensile strength of 85, 119 as kgf / cm ² and 168 kgf / cm ^2, and Comparative Examples 81, 88 kgf / cm ^2, And 153 kgf / cm < ^{2 &} gt ;. Therefore, the examples are shown in the comparative examples ^. It can be seen that the mechanical properties are excellent.

Further, in the case of the wear loss rate, the ratio of the embodiment is only 3.2%, compared with 3.9% in the comparative example. That is, it can be seen that the wear loss of the example is 18% or less as compared with the comparative example. That is, it can be seen that the use of silicon carbide as the filler in the case of the embodiment leads to an excellent wear loss rate.

On the other hand, the elongation was 218% and 209%, respectively, indicating that there was no significant difference between the comparative example and the example.

As a result, according to the present invention, it is found that the wear resistance is improved and the mechanical properties are similar to or better than those of the comparative example.

Item Comparative Example Example Related Standards Basic Properties Hardness (Shore A) 81 85 ASTM D471 100% modulus (kgf / cm ² ) 88 119 Tensile strength (kgf / cm ² ) 153 168 Elongation (%) 218 209 Abrasion resistance
(Taber) Wear loss rate (%) 3.9 3.2

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

10: Monotube type shock absorber 11: Cylinder tube
12: Piston rod 13: Piston valve
13a: Oil passage 14: Separation piston
15: O-ring 16: Road guide
17a: tension chamber 17b: compression chamber
18: gas chamber 100: sealing member of a shock absorber

Claims (4)

A rubber composition for a shock absorber sealing member comprising a polymer, a filler, a crosslinking agent, an antioxidant, a plasticizer and a crosslinking aid,
The polymer is an acrylonitrile-butadiene rubber (NBR)
The filler has 50 to 150 parts by weight based on 100 parts by weight of the polymer,
Wherein the filler comprises silicon carbide powder having 5 to 15 parts by weight based on 100 parts by weight of the polymer. The method according to claim 1,
Wherein the nitrile content of the acrylonitrile-butadiene rubber is 18 wt% to 23 wt%. The method according to claim 1,
Wherein the antioxidant comprises phenylene diamines having 1 to 5 parts by weight based on 100 parts by weight of the polymer. The method of claim 3,
The anti-aging agent includes N-phenyl-N'-isopropyl-P-phenylenediamine and Polymerized 2,2,4-trimethyl-1,2-dihydroquinoline resin And a rubber composition for a shock absorber sealing member.

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