KR101423490B1 - Rubber composite for piston seal - Google Patents

Abstract

The present invention provides a low friction and low abrasion resistance NBR rubber composition for a piston seal with improved wear resistance and resistance to abrasion. The low friction and low abrasion resistance NBR rubber composition for a piston seal of the present invention comprises a polymer composed of acrylonitrile butadiene (NBR) and 2 to 10 parts by weight based on 100 parts by weight of the polymer, And 4 to 20 parts by weight based on 100 parts by weight of the polymer, and a filler for abrasion wear comprising an inorganic pigment containing a metal compound as a main component.

Description

[0001] RUBBER COMPOSITE FOR PISTON SEAL [0002] BACKGROUND OF THE INVENTION [0003]

The present invention relates to a low friction and low abrasion resistance NBR rubber composition for a piston seal, and more particularly, to a low friction and low abrasion resistance NBR rubber composition for a piston seal which is mounted on an end of a piston in a cylinder and prevents hydraulic pressure from leaking out of the cylinder. will be.

The forklake used in the construction site adjusts the front mounted shovel and moves the soil.

Raising and lowering the shovel and adjusting the angle of the shovel is accomplished by adjusting the hydraulic cylinder. In this case, the pressure of the fluid in the hydraulic cylinder is converted into the motion of the piston.

The piston seal is attached to the end of the piston in the hydraulic cylinder and functions to prevent the hydraulic pressure from leaking out of the cylinder. Therefore, when there is a problem with the piston seal, the hydraulic pressure leaks and the force is not sufficiently transmitted to the shovel.

Typically, the piston seal is typically comprised of an acryonitrile butadiene (NBR) rubber composition.

However, since the piston seal moves in close contact with the inside of the cylinder during the reciprocating motion, a large amount of frictional force is generated and a large energy is required to operate the piston. Therefore, in order to improve fuel economy, it is necessary to have a smaller frictional force.

The cylinder in contact with the piston seal is a metal material. As a result, the piston seal, which is a rubber material, wears due to long-time reciprocation, and therefore, it is necessary that the piston seal has excellent abrasion resistance. Generally, in order to improve the abrasion resistance of the NBR oil seal, a reinforcing filler such as graphite, potassium titanate or the like is added in addition to the conventional carbon black. The graphite or potassium titanate improves the lubricity of the rubber. Accordingly, the friction with the shaft is small, and the slip property is improved, thereby improving the abrasion resistance.

However, the recent improvement of the fuel efficiency of the vehicle and the longevity of the parts are continuously required, so that the technique of applying the ordinary reinforcing filler has a limitation.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an NBR rubber composition for a piston seal with improved friction resistance and wear resistance.

 Accordingly, the low friction and low abrasion resistance NBR rubber composition for a piston seal according to a preferred embodiment of the present invention comprises a polymer composed of acrylonitrile butadiene (NBR) and 2 to 10 parts by weight based on 100 parts by weight of the polymer, An abrasion-resistant filler made of carbon fiber, and an abrasion-resistant filler consisting of an inorganic pigment having a metal compound as a main component in an amount of 4 to 20 parts by weight based on 100 parts by weight of the polymer.

In this case, the present invention may further include a main filler consisting of carbon black having 80 to 120 parts by weight based on 100 parts by weight of the polymer.

In this case, the inorganic pigment may contain iron oxide as a main component.

According to the present invention having the above-described constitution, the abrasion performance of the rubber is improved by using an inorganic pigment containing a metal compound as a main component as a filler. Further, carbon fiber is used as a filler to improve the friction performance of the rubber. As a result, the durability of the entire oil seal is improved.

Hereinafter, preferred embodiments of the low friction and low abrasion resistance NBR rubber composition for a piston seal of the present invention having improved abrasion resistance will be described in detail.

The low friction and low abrasion resistance NBR rubber composition for a piston seal according to a preferred embodiment of the present invention comprises a polymer composed of acrylonitrile butadiene (NBR), a wear resistant filler, and a friction resistant filler.

The polymer is an acrylonitrile butadiene rubber (NBR) produced by emulsion copolymerization of acrylonitrile and butadiene.

Acrylonitrile butadiene rubber is a copolymer of acrylonitrile and butadiene. The acrylonitrile-butadiene rubber has different properties depending on the content of acrylonitrile.

In the present invention, the content of acrylonitrile may be 15 to 45 wt%. When the content is less than 15 wt%, the oil resistance is deteriorated. If the content is more than 45 wt%, the rubber elasticity and low-temperature flexibility may be lower than appropriate levels.

 The filler for abrasion resistance is composed of an inorganic pigment containing a metal compound as a main component. The pigment is generally used for coloring the rubber synthetic resin by being mixed with a rubber synthetic resin. The pigment is usually used in an amount of 1 to 3 parts by weight relative to 100 parts by weight of the polymer. An inorganic pigment containing a metal compound as a main component is produced by using a metal compound such as zinc, titanium, lead, iron, copper, or chromium as a raw material and usually has a function of coloring the rubber.

Conventionally, a reinforcing filler is used to improve physical properties (abrasion resistance, tensile strength, etc.) of vulcanized rubber blended with rubber. According to the present invention, the reinforcing filler is not used or minimally used, and addition of an inorganic pigment improves the mechanical abrasion resistance of the rubber itself, and also serves as an increasing function.

In this case, the inorganic pigment is preferably added in an amount of 4 to 40 parts by weight based on 100 parts by weight of the polymer. If the weight part is less than 4 parts by weight, the inorganic pigment does not have sufficient abrasiveness and the weight part is more than 40 parts by weight , The elasticity is weakened because of being too hard, and there is a side effect that the inside of the relative cylinder is scratched.

In this case, it is more preferable that the inorganic pigment contains iron oxide as a main component. The iron oxide is usually added as a red pigment in an amount of 1 to 3 parts by weight to the rubber to give a red color. In the present invention, an iron oxide component having 4 to 20 parts by weight as a wear resistant filler is added to improve the abrasion resistance of the rubber . In this case, the iron oxide may be iron trioxide (Fe ₂ O ₃ ).

The wear resistance of the rubber itself can be improved by using an inorganic pigment as a filler.

On the other hand, the filler for friction resistance included in the present invention is made of carbon fiber. When the carbon fiber is mixed with the polymer, the carbon fiber becomes a filler shape, and a portion protruding slightly toward the outside is formed. As a result, the portion of the piston seal contacting the cylinder becomes the filler portion of the carbon fiber. Accordingly, the area in contact with the cylinder becomes small. Therefore, it does not stick well to the cylinder.

Also, carbon fiber has less elasticity than NBR rubber. Therefore, slip occurs well during sliding movement relative to the cylinder. Accordingly, the piston seal is excellent in wear resistance.

On the other hand, carbon black can be used as the main filler. The main filler means a substance to be added to the polymer in order to improve the overall properties such as strength and durability, or to be added for the purpose of increasing the amount, increasing the amount, and reducing the cost of the product. It functions to improve tensile strength and elongation which are difficult to improve with fillers.

In this case, the main filler may be Seast GSO product of TOKAI CARBON. The carbon black may be 80 to 120 parts by weight based on 100 parts by weight of the polymer.

According to the present invention, the wear resistance and the frictional resistance of the finished piston seal are improved by adding carbon fiber to the wear resistant filler and adding an inorganic pigment as the filler for friction resistance.

Hereinafter, the rubber composition according to the embodiment of the present invention (hereinafter referred to as "the embodiment" for convenience) will be referred to as a rubber composition of a conventional piston seal (hereinafter referred to as "comparative example" 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.

In the case of the embodiment, no reinforcing filler was used. Instead, iron oxide was used as a wear-resistant filler, and carbon fiber was used as a friction-resistant filler.

Components (parts by weight) Comparative Example Example Polymer NBR ^{1 )} 100 100 Primary filler Seast GSO ^{2 )} 70 100 HTC # 20 ³⁾ 90 0 My Friction Filler DONACARBO S-2404 ⁴⁾ 0 4 Wear filler for abrasion Bayferrox 140M ^{5 )} 0 6 Vulcanizing agent Vulcar ^{6 )} 3 3 Crosslinking auxiliary Stearic Acid ^{7 )} 2 2 ZnO KS-2 ⁸⁾ 5 5 Crosslinking accelerator DM-10 ⁹⁾ 3 3 Plasticizer DOZ ^{10 )} 30 30 Antioxidant KUMANOX 3C ^{11 )} 6 6 Processing aid HIKOTACK C-90 ¹²⁾ 3 3 1) NBR: Acrylonitrile-Butadiene Rubber (synthetic rubber), JSR N250S, JSR
2) Seast GSO: - (C) n-, TOKAI Carbon
3) HTC # 20: - (C) n-, Nippon Kayakan Co.,
4) DONACARBO S-2404: - (C) n-, OSAKA GAS CHEMICAL
5) Bayferrox 140M: Iron Oxide (Fe ₂ O ₃ ), Bayer
6) Vulcar: Poly Susphide, TOYO CHEMICAL
7) Stearic Acid: Stearic Acid, NATOLEO
8) ZnO KS-2: Zinc oxide,
9) TBT-P: Tetramethyl-Thiuram Disulfide, KAWAGUCHI CHEMICAL
10) DOZ: di-2-ethylhexyl Azelate, 三建 化工
11) KUMANOX 3C: N-Phenyl-N'-Isopropyl-P-Phenylendiamine,
12) HIKOTACK C-90: Cumarone Resin, Kolon Oil Painting

Table 2 is a table comparing the results of the abrasion resistance test and the abrasion resistance test.

In this case, the abrasion resistance test was carried out by the Taber abrasion test (the abrasion rate was measured after 1000 revolutions at a rotation speed of 70 rev / min), and the abrasion degree was measured and satisfied the KS M ISO 5470-1_2007.

The friction resistance test was carried out under the conditions of a load of 100 g, a moving speed of 50 mm / min, and a measurement distance of 25 mm, and the kinematic friction coefficient was measured, satisfying KS M ISO 15113_2007.

As a result, the hardness of the example was 83 Shore A, which was the same as the comparative example. The tensile strength was 178 Kgf / cm ² , 153 Kgf / cm ² Respectively.

Further, in the abrasion resistance test, it is found that the abrasion rate of the examples is 1.3%, which is significantly lower than 1.9% of the comparative example.

In the abrasion resistance test, the coefficient of dynamic friction was 1.5 in the case of the example, 2.0 in the case of the comparative example, and the friction coefficient was small in the case of the example.

Item Comparative Example Example Related Standards Abrasion test Wear rate (%) 1.9 1.3 KS M ISO 5470-1_2007 Friction test Coefficient of friction 2.0 1.5 KS M ISO 15113_2007 Tensile test Tensile strength (Kgf / cm ² ) 153 178 KS M 6518_2001 Hardness (points) 83 83 Elongation (%) 110 130

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 (4)

A polymer composed of acrylonitrile butadiene (NBR);
2 to 10 parts by weight based on 100 parts by weight of the polymer, an anti-friction filler consisting of carbon fiber; And
A filler for abrasion wear comprising an inorganic pigment having iron oxide as a main component and 4 to 20 parts by weight based on 100 parts by weight of the polymer;
And a low friction and low abrasion resistance NBR rubber composition for a piston seal. The method according to claim 1,
A main filler composed of carbon black having 80 to 120 parts by weight based on 100 parts by weight of the polymer;
Wherein the low friction and low abrasion resistance NBR rubber composition for a piston seal further comprises a thermoplastic elastomer. delete 3. The method according to any one of claims 1 to 2,
Wherein the piston seal is interposed between a piston piston mounted in a hydraulic cylinder for adjusting a shovel mounted on the front side of the forklra and the inside of the cylinder.