JPH08134270A - Sealing rubber material - Google Patents

Abstract

PURPOSE: To obtain a sealing rubber material which has good mechanical characteristics and does not cause breakage, such as biting, even when no reinforcing member is provided and which has good sealing properties and a high reliability. CONSTITUTION: The material is obtd. by cross-linking a compsn. comprising a hydrogenated NBR pref. in an amt. of 100 pts.wt., a metal salt of an ethylenically unsatd. carboxylic acid pref. in an amt. of 10-40 pts.wt. and an org. peroxide pref. in an amt. of 4-6 pts.wt. Examples of the peroxide are dicumyl peroxide and 1,3-bis(t-butylperoxyisopropyl)benzene. A suitable metal salt of an ethylenically unsatd. carboxylic acid is zinc dimethacrylate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved rubber material suitable as a seal or packing material.

[0002]

2. Description of the Related Art Generally, oil from joints and sliding parts,
In a sealing material that seals a fluid such as water or air so as not to leak, it is considered that it is very important to have high rubber elasticity in order to maintain good sealing performance. Conventionally, synthetic rubber or natural rubber such as butyl rubber, styrene-butadiene rubber (SBR), and chloroprene rubber (CR) has been used as the rubber material for such a seal. In particular, silicone rubber, chloroprene rubber (C) are used for seals and packing materials such as O-rings used in high hydraulic devices such as hydraulic motors, hydraulic pumps, hydraulic cylinders, and hydraulic valves.
R), nitrile rubber (NBR) and other heat resistant rubber materials having excellent oil resistance are used.

[0003]

However, in such a conventional sealing material, since the strength is not sufficient and it is easily deformed, when the pressure of the fluid becomes high, it is squeezed out from the gap (biting) and broken. Alternatively, there is a problem such as breakage and deterioration of sealing performance. Therefore, particularly in the case of the O-ring, a backup ring made of resin or the like is arranged for reinforcement on at least the low pressure side of the seal material to prevent damage due to the biting of the seal material.

However, in such a method, since an expensive backup ring is used, not only the cost is increased, but also the work of assembling the sealing material and the reinforcing material is troublesome and time-consuming.

The present invention has been made in view of the above points, and it does not cause breakage such as biting even if a reinforcing material such as a backup ring is not provided, and the sealing performance is good and the reliability is high. An object is to provide a high rubber material for sealing.

[0006]

The rubber material for a seal of the present invention is characterized in that hydrogenated NBR is blended with a metal salt of an unsaturated ethylenic carboxylic acid and an organic peroxide, respectively, and is crosslinked. To do.

Further, in such a rubber material for sealing, the metal salt of unsaturated ethylenic carboxylic acid and the organic peroxide are mixed in an amount of 100 parts by weight of hydrogenated NBR.
It is characterized by 10 to 40 parts by weight and 4 to 6 parts by weight, respectively.

Further, it is characterized in that 10 to 30 parts of carbon black and 4 to 6 of organic peroxide are added to 100 parts of the rubber material for sealing.

The hydrogenated NBR used in the present invention is N
By adding hydrogen to the double bond contained in BR (butadiene acrylonitrile rubber) and making it difficult for the recombination reaction of sulfur to occur, it is possible to prevent the rubber elasticity from decreasing with time, which is an advantage of NBR. The heat resistance is improved while maintaining. In the present invention, it is desirable to use one having a hydrogenation rate of 80% or more, and as a commercially available product of such hydrogenated NBR, Zettopol or the like can be used.

In the present invention, the metal salt of unsaturated ethylenic carboxylic acid is preferably a metal salt of di (meth) acrylic acid, such as zinc dimethacrylate or aluminum dimethacrylate. .

Further, as the organic peroxide (organic peroxide) used as a crosslinking agent for the hydrogenated NBR, dicumyl peroxide and 2,5-dimethyl-2,5-di (t-butylperoxy) are used. Hexane, 2,5-dimethyl -2,5-
Di (t-butylperoxy) hexyne-3,1,3-bis (t-butylperoxyisopropyl) benzene, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,
4-dichlorobenzoyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, t-
Butyl peroxybenzoate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane and the like can be mentioned.

In the present invention, the hydrogenated NBR described above is used.
When 100 to 40 parts by weight of unsaturated ethylenic carboxylic acid metal salt and 4 to 6 parts by weight of organic peroxide are mixed, respectively, sufficient rubber elasticity is required as a sealing material. High strength can be obtained without losing. That is, the blending amount of the organic peroxide is
When the amount is less than 4 parts by weight per 100 parts by weight of R, the crosslinking reaction of hydrogenated NBR does not sufficiently occur, resulting in low rubber elasticity and poor sealing property and adhesiveness. When the compounding amount is more than 6 parts by weight, the mechanical properties are deteriorated, and in any case, it cannot be put to practical use as a sealing material. Similarly, the amount of unsaturated ethylenic carboxylic acid metal salt compounded is 10 per 100 parts by weight of hydrogenated NBR.
When the amount is less than 40 parts by weight, the rubber elasticity is low and the sealing property is deteriorated. On the contrary, when the amount is more than 40 parts by weight, the mechanical properties are deteriorated, which is not preferable.

The rubber material for sealing of the present invention is obtained by adding 10 to 60 parts by weight of carbon black per 100 parts by weight of hydrogenated NBR and a filler such as zinc white to the mixture of the above components. Is obtained by crosslinking by heating.
In addition to these basic formulations, softeners, plasticizers,
Additives such as anti-aging agents and processing aids may be added within a range that does not impair the effects of the present invention.

[0014]

In the rubber material of the present invention, hydrogenated NBR is used.
In addition, a predetermined proportion of organic peroxide is blended as a cross-linking agent, and unsaturated ethylenic carboxylic acid metal salt is blended and cross-linked at an appropriate proportion, resulting in good rubber elasticity, heat resistance and oil resistance. And has high mechanical strength. Therefore, when such a rubber material is used as a seal or packing material for an O-ring or the like, good sealing can be achieved without causing the seal material to stick out or be caught without using a reinforcing material such as a backup ring. Performance is demonstrated, and the work at the time of assembling can be simplified and the cost can be reduced.

[0015]

EXAMPLES Examples will be described below, but the present invention is not limited to these examples.

Examples 1 to 4 A rubber composition obtained by mixing the components of the composition shown in Table 1 was molded into a sheet by a conventional method and then heat-crosslinked to produce a sealing material (sample). did. Next, the normal condition and heat aging test (150 ° C × 7
Hardness (JIS A) after heating, tensile strength (kg / cm
² ), elongation (%), and 100% tensile modulus (kg / cm ² ) were measured. The measurement results are shown in the lower column of Table 1.

[0017]

[Table 1] From this table, the peroxide cross-linked products of hydrogenated NBR obtained in the examples have good rubber elasticity and high mechanical strength, and these properties are not so much after the heat aging test. It was found that the heat resistance did not decrease and the heat resistance was excellent.

The rubber compositions obtained in the examples are molded and crosslinked by a conventional method using a mold having a predetermined shape, and O
Rings were manufactured. Next, when the obtained O-ring was actually used as a refueling type piston seal, protrusion and biting did not occur without using a backup ring, and the sealing performance was good. Further, even after the piston was operated for a long period of time, neither cracking nor abrasion occurred, nor did it swell with oil.

[0019]

As is apparent from the above examples, the rubber material of the present invention has good rubber elasticity, high mechanical strength, and excellent heat resistance and oil resistance. . Therefore, when such a rubber material is used as a seal or packing material for an O-ring or the like, the sealing material does not squeeze out or get caught without using a reinforcing material such as a backup ring. The sealability is demonstrated, and the work at the time of assembling can be simplified and the cost can be reduced.

[0020]

Claims (2)

[Claims] 1. A rubber material for sealing, comprising a hydrogenated nitrile rubber and a metal salt of an unsaturated ethylenic carboxylic acid and an organic peroxide, respectively, which are cross-linked and cross-linked. 2. An unsaturated ethylenic carboxylic acid metal salt and an organic peroxide are blended in an amount of 100 parts by weight of hydrogenated nitrile rubber.
The rubber material for sealing according to claim 1, which is 10 to 40 parts by weight and 4 to 6 parts by weight with respect to parts by weight, respectively.