JPS62285972A - Heat-resistant sealing material - Google Patents

Abstract

PURPOSE:To obtain a heat-resistant sealing material capable of exhibiting a good sealing performance stably over a long period of time even under high- temperature conditions, by impregnating a sealing material substrate composed of a heat-resistant fiber such as a sheet, a rope, a (non)woven fabric, etc. with a heat-resistant sinterable binder. CONSTITUTION:A sealing material substrate composed of a heat-resistant fiber such as alumina fiber, silicon carbide whisker, etc., such as a sheet, a rope, a woven fabric, a nonwoven fabric, etc., is impregnated with a heat-resistant sinterable binder. If desired, the impregnated product is heated to sinter it. Examples of the binder are those obtd. by mixing glass frit such as aluminum phosphate frit, sodium borosilicate frit, etc. with a powder of titanium oxide, alumina or zirconia and dispersing, the mixture in water or further adding an organopolysiloxane thereto. The heat-resistant sealing material is suitable for use as a packing for the valve of high-temperature gas pipe.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a sealing material that exhibits good sealing properties even at high temperatures of 500° C. or higher.

[Prior art] Sealing materials used for backings or gaskets of valves, cocks, flanges, etc. in piping and equipment that handle high-temperature fluids such as high-temperature gases and high-temperature liquids exhibit excellent heat resistance even in high-temperature environments. This is required, and various proposals have been made so far.

Typical heat-resistant sealing materials include (1) polyester resin, phenol resin, and epoxy resin.

Thermosetting resin such as urea resin, glass self-fiber, asbestos fiber,
(2) The above-mentioned heat-resistant fiber is impregnated with a highly heat-resistant fluorinated ethylene resin, (3)
Examples include those made of heat-resistant rubber such as polyacrylic rubber, fluorine rubber, and silicone rubber, and (4) those made of asbestos or other inorganic materials.

[Problems to be Solved by the Invention] However, among the above-mentioned heat-resistant sealing materials, those in which heat-resistant fibers are impregnated with the thermosetting resin mentioned in (1) have a heat resistance temperature of 260° C. or lower; (2), which uses polyfluoroethylene resin, has a temperature of about 260°C, and even when used intermittently, it is at most 300°C, and (3), which uses acrylic rubber, has a temperature of about 170°C, fluorine rubber, which has a temperature of 200 tons, and silicon For rubber, the limit is about 250 tons. Also(
The upper limit for asbestos seals (4) is about 450 tons, and if it exceeds this, there is a problem that crystal water will be lost and it will become brittle. Other inorganic materials, although good in heat resistance, have poor sealing effectiveness. There was a problem.

In this way, known heat-resistant sealing materials have a low heat resistance temperature, and no matter how devised they are, the limit is about 500 tons, and if they are used beyond their respective allowable heat resistance temperatures, the physical properties of the sealing material may deteriorate due to embrittlement or deterioration. When polished, in some cases it may decompose and generate harmful gases, making it unable to function as a seal and causing fluid leaks and accidents.

Therefore, the present invention aims to provide a heat-resistant sealing material that can solve the above-mentioned problems, especially a heat-resistant sealing material that can exhibit good sealing performance even at high temperatures of 500°C or higher. .

[Means for Solving the Problems] The heat-resistant sealing material of the present invention that can solve the above-mentioned problems is a sheet made of heat-resistant fibers.

The main structure is that a sealing material base material such as rope, woven fabric, non-woven fabric, etc. is impregnated with a heat-resistant sintering type binder, and the heat-resistant sintering agent is applied in advance to the sealing part. Also provided by the present invention are those that are heated and sintered prior to application. In the following description, the former may be referred to as a soft sealing material, and the latter may be referred to as a hard sealing material to distinguish them.

[Operations] First, in the soft sealing material of the present invention, a heat-resistant sintered binder is added to a sealing material base material (hereinafter also simply referred to as a sheet, etc.) such as a sheet 10 made of heat-resistant fiber, woven fabric, or non-woven fabric. Impregnated with and used as a sealant for high temperatures. In this sealing material, when the binder is in an unsintered state, the elasticity of the fibers themselves and the elasticity exerted by the form of the processed product are not lost, making it easy to process small seals, punching, and complex shapes. Furthermore, once use begins, the sintered binder progresses in sintering due to the high heat of the usage environment, maintaining a high level of sealing effect, resulting in particularly good sealing performance in fields where sealing pressure is high. In addition, by heating in advance, when the sintered binder is sintered, it becomes a hard sealing material, making it easy to handle large-sized processed products and suitable for applications in sectors where the sealing pressure is not so high.

The heat-resistant fibers used in the present invention include alumina, alumina-silica, zirconia, boron 1 silicon carbide, carbon stainless steel, carbon, glass, polyimide, or asbestos 1
Examples include fibers made of slag wool, whiskers such as silicon carbide whiskers, silicon nitride whiskers, potassium titanate whiskers, barium titanate whiskers, and rock wool, and sheets processed using these alone or in combination of two or three types. , rope, woven or non-woven fabric and impregnated with a sintered binder.

The sintered binder of the present invention is described in (8) and (8) below.
Examples include things like.

(A) Glass frits, such as lead cauli frit, borosilicate frit, titanium frit, lead lithium frit,
A mixture of one or more solid powders selected from strontium frit, magnesia frit, zircon frit, etc., silicate lime, alumina, zirconia, silicon carbide, silicon nitride, aluminum nitride, boron nitride, and other ceramic materials is added to water. These may contain heat-resistant additives or heat-resistant powders such as talc, silica, mica powder, comb, graphite, titanium oxide, chromium oxide, iron oxide, etc. For example, when heated to 400° C. or higher, ceramic materials (especially glass frit) are melted and turned into ceramics.

(B) This is the component (A) mixed with organopolysiloxane and dispersed in a solvent.
When heated to 0° C., the organic groups of the organopolysiloxane decompose and leave, and together with the melting of the ceramic material (particularly the glass frit), the organopolysiloxane compatibilizes and integrates with the polysilochitin skeleton to form a ceramic.

In both (8) and (8), it is desirable to combine ceramic materials with different melting points. The reason for this is that the sealing effect in the unsintered state is further improved by the melting viscosity of each material having a different melting point. Examples of the organopolysiloxane include methyl silicone, phenylmethyl silicone, and a copolymer of vinyl phenyl siloxane and phenyl methyl siloxane.

In both (A) and (B), when blending the sintered binder, consideration should be given to obtaining the required film properties in the unsintered state. Weight%, heat-resistant pigment 5-75% by weight, solvent 10-15% by weight, organopolysiloxane 5-40%
Preferably, it is expressed as % by weight. In addition, in (B), the physical properties of the unsintered film are strengthened by the organopolysiloxane's own function as a binder, so sealing materials using this material exhibit excellent sealing properties even at low temperatures, and can be used from low to high temperatures. It can be used over a wide range of areas.

As a method of impregnation, dipping, knife coating, roll coating, spray coating, etc. can be used, but the impregnation means is not limited to the present invention. The elasticity can also be adjusted by changing the impregnation rate of the sintered binder into the sheet made of heat-resistant fibers, but the general impregnation rate is preferably 5 to 80%. If only the surface layer is impregnated, the elasticity of the unimpregnated fibers in the center will be utilized, resulting in better sealing properties.

After a sheet or the like is impregnated with a sintered binder and dried to remove volatile substances as described above, it is processed into a predetermined shape or thickness and used as a soft sealing material. In this case, heat is applied during actual use, and the sintered binder is sintered and turned into ceramic as described above. Also, 400 yen in advance
The sintered binder may be sintered by heat treatment at ~500°C and used as a hard sealing material.

[Example] (Example 1) A sintered binder was obtained by dispersing the blends (A) and (B) having the compositions shown in Table 1 for 30 minutes in a shaker. A sheet and a rope of alumina-silica fiber (heat resistant temperature: 1260° C.) were dipped in the agent, and after being impregnated, they were pulled up and air-dried for 30 minutes. Thereafter, drying was performed at 120° C. for 1 hour to obtain the desired backing. Cut this material to the specified size and fix it as a sealing material for the piping flange.
It was used by passing exhaust gas at ℃. During this process, this backing was made of ceramic, and later JJ? 10 in FA
No abnormality occurred even during constant use at 00°C. (A
) and (B) formulations gave similar results.

Especially those containing CB) are at low temperatures (when the sintered binder is not sintered)
The sealing performance was good over a range of temperatures from 10 to 100% (sintered type binder sintered).

(Example 2) After being wrapped and impregnated in the same sinter type binder used in Example 1, it was pulled up and air-dried for 30 minutes. Then 120℃,
After drying for 1 hour, pressing was performed at a temperature of 250°C to obtain a sheet with a thickness of 1 mm. This was cut to a predetermined size, heat treated at 400 to 500°C, fixed as a gasket in a place where a temperature of 800°C was applied, and when tested, it withstood use without any abnormality. Similar results were obtained for both formulations (A) and (B).

[Effects of the Invention] As described above, the heat-resistant sealing material of the present invention can withstand high temperatures of 500° C. or higher and can stably exhibit good sealing properties over a long period of time.

Claims (2)

[Claims] (1) A heat-resistant sealing material, characterized in that it is made by impregnating a heat-resistant sintered binder into a sealing material base material such as a sheet, rope, woven fabric, or non-woven fabric made of heat-resistant fibers. (2) Impregnating a heat-resistant sintered binder into a sealing material base material such as a sheet, rope, woven fabric, or non-woven fabric made of heat-resistant fibers;
A heat-resistant sealing material characterized in that a heat-resistant sintered binder is sintered by heating.