JP2538509B2 - Sheet-like gasket for fluid sealing - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid seal used for sealing an internal fluid in various industrial fluid devices such as pipe connecting portions such as pipe joints, valves and pumps. The present invention relates to a sheet-shaped gasket for a car.

[0002]

2. Description of the Related Art As a sheet-like gasket for sealing fluids of this type, generally, asbestos beater sheets containing white asbestos and a rubber latex binder as main components, and a vulcanizing agent in addition, and asbestos are used. An asbestos joint sheet is known, which is composed of a main component, and a rubber as a binder for asbestos, and a rubber chemical such as a vulcanizing agent.
Since these sheet-shaped gaskets containing asbestos as a main component are harmful to the human body and pose a problem of environmental pollution, their use is being limited, and the development of gaskets that do not use asbestos is urgently needed. There is.

As a sheet-like gasket for fluid sealing which does not use such asbestos, conventionally, a fiber base material such as aramid fiber or rock / slag fiber, an inorganic filler such as talc or kaolin, rubber, or a rubber chemical is used. There is known a gasket formed by uniformly dispersing a binder composed of (1) and then forming it into a sheet.

[0004]

However, the conventional fluid-sealing sheet-like gasket having the above-described composition has a state in which it is strongly fastened to the pipe connection portion or the flange portion of various fluid devices via bolts or the like. At this time, when the operating temperature condition becomes 200 ° C to 300 ° C,
The softening of the rubber as the binding material progresses rapidly, and the tightening force decreases.As a result, the tightening force required to maintain good sealing performance cannot be maintained, and the internal fluid decreases as the sealing performance decreases. However, there are problems such as leakage of oil and damage to the gasket itself due to the internal pressure of the sealing fluid.

The present invention has been made in order to solve the above problems, and suppresses the reduction of the tightening force due to the softening of the rubber as the binder due to the use under the high temperature condition and the high temperature and high pressure condition. However, it is an object of the present invention to provide a sheet-like gasket for fluid sealing which can ensure stable sealing performance for a long period of time without causing leakage or damage.

[0006]

To achieve the above object, a sheet gasket for fluid sealing according to the present invention comprises:
Organic fibers such as aramid fiber, phenol resin fiber, aromatic polyester fiber, aromatic polyimide fiber and /
Alternatively, 5 to 20 wt.% Of a fiber base material composed of inorganic fibers such as rock slag fiber, alumina-silicate fiber, alumina fiber, quartz glass fiber, carbon fiber and metal fiber.
%, 40 to 70 wt% of an inorganic filler made of an inorganic powder selected from kaolin, clay, talc, silica, mica, vermiculite, and an alkaline earth metal, and 5 to 20 wt% of acid-treated unexpanded graphite. %, And a binder made of rubber and rubber chemicals.

[0007]

In the sheet-like gasket for fluid sealing having the above construction, each compounding material plays the following role. The fibrous base material forms a uniform mesh structure inside the sheet and is adhered by rubber as a binding material to support mechanical strength such as supporting tensile strength and compression load on the sheet to prevent expansion during compression. It is to be given.
Therefore, the compounding amount is preferably 5 to 20 wt%, and when it exceeds 20 wt%, the amount of fibers is large and the voids become too large, resulting in increased leakage, and when it is less than 5 wt%, the mechanical strength is reduced. Becomes weaker, and the tightening force cuts the gasket, resulting in poor handleability. As the organic fiber in this fiber base material, at least one kind is selected from organic fibers such as aramid fiber, phenol resin fiber, aromatic polyester fiber, aromatic polyimide fiber, and aromatic polybenzimidazole fiber.

On the other hand, the inorganic fibers in the fiber base material are improved in heating strength, particularly in preventing thermal deformation (thermal creep) at the time of initial heating, in improving resilience by the fiber filler, and during drying after papermaking, for example. It contributes to the prevention of shrinkage. Therefore, the compounding amount thereof is preferably 5 to 20 wt%, and when it exceeds 20 wt%, the amount of fibers is large and the voids become too large, leakage increases, and the tightening resistance load at which the fibers break during tightening is increased. Decreased, 5 wt%
If it is less than the above range, the strength during heating is not sufficient and the shrinkage during drying after papermaking becomes large. Examples of the inorganic fiber include rock slag fiber, alumina-silicate fiber, alumina fiber, zirconia fiber, ceramic fiber such as rock wool, quartz glass fiber, glass fiber such as high silicate glass fiber, carbon fiber, phosphate fiber, metal fiber. At least one kind is selected from inorganic fibers such as.

The inorganic filler functions as a filling material,
It not only improves the sealing property to a certain level, but also contributes to the improvement of tightening load and heat resistance. Therefore, the compounding amount thereof is preferably 40 to 70 wt%, and when it exceeds 70 wt% from the relationship of the compounding amount with other materials, the amount of the inorganic filler is too much and the strength is apt to be lowered, and it is less than 40 wt%. Then, the tightening load when mounting the gasket is likely to decrease, and in an extreme case, the gasket may be cut and leakage may increase, and the stress may be greatly relaxed during heating. As the inorganic filler, one or more kinds of kaolin, clay, talc , silica, mica , vermiculite, etc., and mainly silicon and aluminum, magnesium, iron, alkaline earth metal, alkali metal Inorganic powders such as hydrous silicate mineral powders can be used.

The rubber as a binder serves as a binder for the above fibrous material and contributes to the improvement of the sealing property. The compounding amount thereof is preferably 5 to 20 wt%, and 20 wt%.
%, The heat resistance is lowered, thermal creep and stress relaxation are increased, and if it is less than 5 wt%, a gap is left and leakage is likely to occur, and the reinforcing effect is insufficient and the handleability is deteriorated. . As this rubber, natural rubber,
Styrene-butadiene-copolymer rubber, ethylene vinyl acetate acrylate copolymer, methacrylic acid ester copolymer, acrylonitrile-butadiene-copolymer rubber, acrylic rubber, silicone rubber, fluororubber or other synthetic or natural rubber latex And one or more solid rubbers are used.

The rubber chemicals include vulcanizing agents, vulcanization accelerators,
A vulcanization aid, a dispersant, an antiaging agent, a plasticizer, a pigment and the like are selected and used according to purposes such as heat resistance, oil resistance, acid resistance and color tone. The blending amount is preferably 1 to 5 wt%.

The acid-treated unexpanded graphite has the function of suppressing the decrease in the stress residual rate, which expands when used at high temperatures and decreases due to softening of the rubber, and also has the function of preventing blow-through damage of the gasket. As the compounding amount,
5 to 20 wt% is preferable, and if it is less than 5 wt%, the stress residual rate is largely lowered, and if it exceeds 20 wt%, the role of retaining the shape of the gasket is lost. As the acid for treating the unexpanded graphite, it is preferable to use sulfuric acid or nitric acid. When treated with sulfuric acid, expansion starts at about 250 ° C., and when treated with nitric acid, about 150 ° C. Expansion begins in the heating zone, which is cooler than sulfuric acid.

Further, the bulk density of the sheet gasket for fluid sealing, which is composed of the above-mentioned respective materials, is preferably set to 0.8 to 1.9 g / cm ³ . If the bulk density is less than 0.8 g / cm ³ , the porosity is large, and there is a risk of fluid permeation leakage. If the bulk density is more than 1.9 g / cm ³ , the flexibility is lost and the compatibility is poor. Deteriorate. The sheet-like gasket for fluid sealing of the present invention can be applied, for example, as a sheet-like gasket for a core of a metal jacket gasket, and can be effectively applied as long as it handles a fluid.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a main part of a sheet gasket for fluid sealing according to the present invention. In FIG.
Is an organic fiber such as aramid fiber, phenol resin fiber, aromatic polyester fiber, aromatic polyimide fiber and / or rock slag fiber, alumina-silicate fiber, alumina fiber, quartz glass fiber, carbon fiber, inorganic fiber such as metal fiber A fibrous base material 11 made of kaolin, clay, talc, silica, mica, vermiculite, an inorganic filler made of an alkaline earth metal inorganic powder,
Unexpanded graphite 12 acid-treated with sulfuric acid or nitric acid
Then, a binder such as natural rubber and a rubber chemical such as a vulcanizing agent are uniformly dispersed and mixed, and then molded into a sheet to produce a sheet gasket 13 for fluid sealing.

Hereinafter, examples of the present invention will be specifically described in comparison with comparative examples. Sample gaskets made of the compounding materials and compounding amounts (wt%) shown in Table 1 were prepared by the paper-making method, and in Example 1, Example 2 and Comparative Example, the bulk density was 1.7 g / cm ³ , and the thickness was 1. A 5 mm sheet-shaped gasket was obtained. Here, the aramid fiber has a fiber diameter or particle size of 0.1 to 20 μm and a fiber length of 0.1 to 1
0 mm, the rock slag fiber has a fiber diameter or particle size of 1 to 50 μm, the fiber length is 1 to 20 mm, and the kaolin mineral has a fiber diameter or particle size of 0.1 to 10 μm.
As unexpanded graphite, fiber diameter or particle diameter is 0.1-5 m
m was used.

[0016]

[Table 1]

A leak test was conducted on each sample gasket prepared from the above-mentioned blended material and blended amount by using the steam test apparatus shown in FIG. In this test, the sample gasket M is clamped between the upper and lower pressure vessels 2 and 3 and the surface pressure is 2
3 by sandwiching it with 5.5 MPa (260 kgf / cm ² ).
It is put into the electric furnace 1 at 00 ° C x 20 hours and the temperature is set to 300.
℃, saturated vapor pressure 8.59MPa (87.6kgf / cm
Under the harsh conditions of ² ), pressure vessels 2, 3 before and after the test
The leak amount was calculated by measuring the weight of the test sample, and the test results are shown in Table 2.

[0018]

[Table 2]

Further, FIG. 3 shows the outline of a stress relaxation test for measuring the stress relaxation at high temperature for each of the above sample gaskets. In this test, a surface pressure of 9.8MP was applied to a sample gasket M via a pair of upper and lower quartz rods 4 and 5 and a load cell 6.
a (100 kgf / cm ² ) under load, hold for 2 hours at room temperature, and then use an electric furnace 7 for 1 hour up to 300 ° C.
The temperature was raised at r and held for 20 hours, and the decrease in the tightening surface pressure at that time was measured. The test results are shown in Table 3.

[0020]

[Table 3]

In the above steam test, the gasket is supported mainly by the frictional force between the gasket seat surface and the gasket against the internal pressure of 300 ° C. saturated steam pressure of 8.59 MPa, and the test results shown in Table 2 are shown. As is clear from the above, in the comparative example, since the frictional force decreases due to the decrease in tightening force, the internal pressure cannot be supported, and the gasket is blown and damaged. On the other hand, in Example 1 and Example 2, since the frictional force for supporting the internal pressure remains, the blowout damage of the gasket does not occur.

Further, in the stress relaxation test, in the case of the comparative example, as is clear from the test results of Table 3, 200
When the temperature is raised from ℃ to 300 ℃, the residual stress (%) decreases due to the softening of the rubber. On the other hand, in the cases of Example 1 and Example 2, the acid-treated unexpanded graphite expands to suppress the decrease in the stress residual rate. Therefore, in Examples 1 and 2, a high stress residual rate is exhibited, and it is possible to sufficiently suppress the deterioration of the sealing property due to the stress relaxation at high temperature.

[0023]

As described above, according to the present invention, a fiber base material that imparts mechanical strength and heating strength to a sheet, such as supporting tensile strength and compressive load to prevent expansion during compression, An inorganic filler made of inorganic powder that functions as a filling material to improve the sealing performance to a certain level and contributes to the improvement of tightening load and heat resistance, and acid treatment that expands the graphite layer due to heating and expands the graphite layer.
By blending the unexpanded graphite with a specific amount in a range that does not cause a role decrease due to each of the materials,
It is possible to prevent the tightening force from decreasing due to the softening of the rubber as a binder when used under high temperature conditions, and even if the sealing fluid has a high pressure, the internal pressure of the gasket may cause blowout damage to the gasket itself. Therefore, even under high temperature and high pressure conditions, it is possible to maintain good sealing performance stably for a long period of time without causing leakage of the internal fluid.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a main part of a sheet-like gasket for fluid sealing according to the present invention.

FIG. 2 is a schematic configuration diagram showing a steam test apparatus for a leak test between the sample gaskets of Examples 1 and 2 of the present invention and a comparative example.

FIG. 3 is a schematic configuration diagram showing a test apparatus for a stress relaxation test of the sample gaskets of Examples 1 and 2 of the present invention and a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric furnace 2,3 Pressure vessel 4,5 Quartz rod 6 Load cell 10 Fiber substrate 11 Inorganic filler such as kaolin mineral 12 Acid-treated unexpanded graphite

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Satoshi Tanimura, Satoshi Tanimura 2-66-3 Nagatanocho, Fukuchiyama City, Kyoto Prefecture, Japan Fukuchiyama Factory, Japan Pillar Industry Co., Ltd. (56) Reference JP-A-7-18249 (JP, A) ) JP-A-5-295351 (JP, A) JP-A-59-68387 (JP, A)

Claims (1)

(57) [Claims] 1. Organic fiber such as aramid fiber, phenol resin fiber, aromatic polyester fiber, aromatic polyimide fiber and / or rock slag fiber, alumina-
5 to 20 wt% of the fiber base material made of inorganic fibers such as silicate fibers, alumina fibers, quartz glass fibers, carbon fibers, and metal fibers, and kaolin, clay, talc, silica, mica, vermiculite,
40 to 70 wt% of an inorganic filler made of an inorganic powder selected from alkaline earth metals, 5 to 20 wt% of an acid-treated unexpanded graphite, and a binder made of rubber and a rubber chemical are blended. A sheet-like gasket for fluid sealing, comprising: