JPH083087B2 - Gasket for high temperature - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high temperature gasket used for equipment operating at high temperature such as a piping connection for a high temperature fluid and a fuel cell.

[0002]

2. Description of the Related Art As a gasket of this type, an asbestos joint sheet gasket has hitherto been generally known. However, this asbestos joint sheet gasket has a use temperature limit of 500 ° C. at most, and at higher temperatures than that. The predetermined sealing performance cannot be exhibited.

Therefore, there has already been proposed a high-temperature gasket which raises the limit of the operating temperature and exhibits excellent sealing performance even at a high temperature of about 1000.degree.
The proposed high-temperature gasket is a glass-based fiber or glass-based powder as an inorganic fiber, and an inorganic powder,
It is formed into a sheet by mixing with an organic binder.

[0004]

However, in the conventional high temperature gasket having the above-described composition, the inorganic fibers such as glass fiber effectively work to maintain the shape of the gasket, but the temperature is lowered from the high temperature to cure. When this happens, warpage or voids are generated, and as a result, contact surface leakage or permeation leakage occurs and it is not possible to completely prevent this, and repetitive use between high temperature and room temperature significantly reduces sealing performance. There was a problem such as.

The present invention has been made in order to solve the above-mentioned problems, and has excellent sealing properties at high temperatures, and does not cause minute leakage even after repeated use, and has stable sealing performance. It is an object of the present invention to provide a high temperature gasket that can be exerted.

[0006]

In order to achieve the above-mentioned object, the gasket for high temperature according to the present invention has an inorganic fiber having heat resistance exceeding a set use temperature as a fiber base material and a set use temperature as an inorganic filler. An inorganic powder having heat resistance exceeding the above range, an inorganic softening agent having a softening point lower than the set operating temperature, and an organic binder are blended.

In the above high temperature gasket, the inorganic fiber is 1 to 30 wt% and the inorganic powder is 0 to 70 w.
It is preferable that t%, the inorganic substance is 20 to 80 wt%, and the bulk density is 1.0 g / cm ³ or more.

[0008]

In the high temperature gasket having the above construction, each compounding material plays the following role. Inorganic fibers contribute to maintaining the shape of the gasket,
If this inorganic fiber is not contained, the retention of the inorganic filler and the inorganic softening material is completely lost. From this meaning,
Inorganic fiber is 1 to 30 wt%, preferably 5 to 20 wt%
It is better to set to%. If it exceeds 30 wt%, the initial density of the gasket does not increase and there is a risk of permeation leakage.

The inorganic powder as the inorganic filler is to reduce the voids of the gasket, enhance the gasket strength at high temperature, and contribute to the improvement of load resistance against tightening and pressure resistance against sealing fluid. In addition, the stability of heat resistance improves durability. The preferable blending amount of this inorganic powder is 0 to 70 wt%, and when it exceeds 70 wt%, the amount of the softening material decreases and it becomes difficult to prevent minute leakage. In addition, the inorganic substance as the inorganic softening material improves adhesion to the gasket seat surface by softening,
It serves to fill the voids, thereby preventing the occurrence of minute leaks. If the blending amount of this inorganic substance is less than 20 wt%, it becomes difficult to prevent minute leakage, and if it exceeds 80 wt%, the gasket will be eluted. Therefore, the compounding amount of the inorganic substance is 2
The range of 0 to 80 wt% is preferable, and it is desirable to appropriately set the compounding amount of each of the inorganic substance and the inorganic powder from the above range according to the set operating temperature.

The organic binder has a function of retaining the shape of the gasket at the initial room temperature. Since this is thermally decomposed and disappears with heating, the compounding amount thereof is preferably as small as possible, and 10 wt% or less is suitable.

[0011]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples. A sheet having the composition shown in FIG. 2 was prepared by a papermaking method. Here, the alumina fibers as the inorganic fibers are sapphire alumina fibers (manufactured by Isolite Industrial Co., Ltd.), the inorganic powder as the inorganic filler is Alumina powder A-420 (manufactured by Showa Denko), and the inorganic substances as the inorganic softening materials are , Glass powder GA-1 (manufactured by Nippon Electric Glass Co., Ltd.) were used, and hemp pulp and Sumika Flex 900 (manufactured by Sumitomo Chemical Co., Ltd.) were used together as the organic binder.

A sealing test was performed on the sample gasket prepared from the above-mentioned composition using the sealing test apparatus shown in FIG. This is because the sample gasket M is sandwiched between the upper and lower flanges 2 and 3 in the electric furnace 1 and the inside 4 of the machine and the pressure tank 5 are connected by a pressurizing pipe 6, and N ₂ gas is introduced into the pressure tank 5. For example, it is a method of closing the valve 7 after filling with 9.8 KPa, pressurizing the inside of the machine 4, and measuring the decrease in the pressure in the pressure tank 5 with the pressure gauge 8.
The conditions of this sealing test are shown in FIG. 3, and the test results are shown in FIG.

As is clear from the test results shown in FIG. 4, in Examples 1 and 2, the morphology of the gasket can be maintained by the reinforcing effect of the inorganic fiber and the inorganic filler, and the inorganic soft material Due to the softening, the gasket can be brought into close contact with the seating surface, and the dust voids can be filled so that minute leakage is almost eliminated. On the other hand, in Comparative Example 1, a gap is left in the gasket to cause leakage, and in Comparative Example 2, the shape of the gasket cannot be maintained and the gasket is eluted.

Further, as the inorganic softening material, it is necessary to use a glass powder having a softening point lower than the set operating temperature of the gas fluid to be used, and it is usually about 100 ° C. higher than the set operating temperature.
Those having a low softening point are preferred. Further, when the gas fluid used has a higher pressure or when the tightening surface pressure can be increased, it is preferable to increase the mixing ratio of the inorganic fiber and the inorganic filler from the viewpoint of gasket durability. On the other hand, when the tightening surface pressure cannot be high, it is necessary to increase the compounding ratio of the inorganic softening material.

FIG. 5 is a table showing a guideline of materials suitable for each set operating temperature. The material shown in FIG. 5 is selected, the set operating temperature is set to 600 ° C., and the composition shown in FIG. Was formed by the papermaking method. Alumina / silica fibers as inorganic fibers are HUC-100SF (manufactured by Toshiba Monoflux), talc powders as inorganic fillers are talc MS (manufactured by Nippon Talc), and 490 ° C softening point glass powders as inorganic softening materials. Is glass powder GA-8
(Manufactured by Nippon Electric Glass) was used. When a sealing test was carried out on the sample gasket prepared with such a composition under the same conditions as in the above-mentioned examples, almost the same results as above could be obtained.

Further, a sheet having the composition shown in FIG. 7 was prepared by a papermaking method with the set operating temperature being 800 ° C.
Alumina / silica fibers as inorganic fibers are HUC-
100SF (manufactured by Toshiba Monoflux), silica powder as an inorganic filler is MK silica (manufactured by Kyoritsu Kiln Raw Materials),
As the 700 ° C. softening point glass powder as the inorganic softening material, glass powder GA-11 (manufactured by Nippon Electric Glass) was used. Also in the sealing test of the sample gasket prepared with such a composition, almost the same result as the above was obtained.

Further, a sheet having the composition shown in FIG. 8 was prepared by a papermaking method with the set operating temperature being 1000.degree. Alumina fiber as the inorganic fiber is Sapphire alumina fiber (manufactured by Isolite Industries), and alumina powder as the inorganic filler is alumina powder A-420.
(Showa Denko) and 930 ° C. softening point glass powder as an inorganic softening material were glass powder GA-33 (Nippon Electric Glass). Also in the sealing test of the sample gasket prepared with such a composition, the result showing excellent sealing performance was obtained.

Furthermore, a sheet having the composition shown in FIG. 9 was prepared by a papermaking method, with the set operating temperature being 1200 ° C. Alumina fiber as the inorganic fiber is Sapphire alumina fiber (manufactured by Isolite Industries), and alumina powder as the inorganic filler is alumina powder A-420.
(Manufactured by Showa Denko) was used. Also in the sealing test of the sample gasket prepared with such a composition, the result that the sealing performance was sufficiently maintained could be obtained.

[0019]

As described above, according to the present invention, the shape is maintained by using the inorganic fiber having the heat resistance exceeding the set use temperature as the fiber base material, while the heat resistance exceeding the set use temperature is used as the inorganic filler. By using the inorganic powder having the property, the strength at high temperature can be increased and a high sealing property at high temperature can be secured. Moreover, by using an inorganic material having a softening point lower than the set use temperature as the inorganic softening material, the voids such as the inorganic fibers are filled with the softened inorganic material even when used at a relatively low temperature. Therefore, it is possible to reliably prevent the occurrence of minute leakage and provide a gasket having an extremely high sealing performance.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a sealing test device used to compare the sealing performance of a high temperature gasket according to an example of the present invention with a comparative example.

FIG. 2 is a chart showing the formulations of Examples and Comparative Examples of sample gaskets having a set use temperature of 700 ° C.

FIG. 3 is a chart showing a sealing test condition of a sample gasket with the composition of FIG.

4 is a chart showing the results of a sealing test of a sample gasket having the composition of FIG.

FIG. 5 is a table showing a guideline of materials used for each set operating temperature.

FIG. 6 is a chart showing the formulations of Examples and Comparative Examples of sample gaskets having a set use temperature of 600 ° C.

FIG. 7 is a table showing the formulations of examples and comparative examples of sample gaskets having a set use temperature of 800 ° C.

FIG. 8 is a chart showing the composition of an example and a comparative example of a sample gasket having a set use temperature of 1000 ° C.

FIG. 9 is a table showing the formulations of Examples and Comparative Examples of sample gaskets having a set operating temperature of 1200 ° C.

[Explanation of symbols]

 1 Electric furnace 2, 3 Flange 5 Pressure tank 8 Pressure gauge

Claims (2)

[Claims] 1. An inorganic fiber having a heat resistance exceeding a set use temperature as a fiber base material, an inorganic powder having a heat resistance exceeding the set use temperature as an inorganic filler, and a softening agent having a heat resistance lower than the set use temperature as an inorganic softening agent. A high-temperature gasket comprising an inorganic material having dots and an organic binder. 2. The inorganic fiber is 1 to 30 wt%, the inorganic powder is 0 to 70 wt%, the inorganic material is 20 to 80 wt%, and the bulk density is set to 1.0 g / cm ³ or more. 1. High temperature gasket.