JPH02266165A - Heat resisting gasket - Google Patents

Abstract

PURPOSE:To secure such a heat resisting gasket that maintains the extent of required sealability even being left behind in high temperature for hours by containing ceramic grains in a nonwoven fabric sheet consisting of a ceramic fiber in an unevenly dispersed state. CONSTITUTION:It is such one that installed each ceramic fiber sheet 1 at both sides of a metal base 2, and the ceramic fiber sheets 1 are composed of those having ceramic grains 12 contained in a nonwoven fabric sheet consisting of ceramic fibers 11 in an unevenly dispersed state. The ceramic fiber sheets 1 are installed in turning a high content side of the ceramic grains 12 to the inside. Each of the ceramic fiber sheets is the smaller in content of the ceramic grains on an outer layer, the better in the viewpoint of sealability on a contact surface with a sealed body. On the other hand, the inside is the higher in the ceramic grain content, the larger in a degree of decrement of porosity in a tightening state of installing a gasket, thus it is desirable in the viewpoint of improvement in the sealability based on this constitution.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is made by providing a ceramic fiber sheet containing unevenly distributed ceramic particles on a metal substrate, which has excellent sealing properties and is suitable for use in exhaust systems of internal combustion engines such as engines. The present invention relates to a suitable heat-resistant gasket.

BACKGROUND ART Conventionally, heat-resistant gaskets made of asbestos have been known. However, as it has been pointed out that asbestos is harmful to the human body, the provision of asbestos-free, heat-resistant gaskets has become an important issue.

Asbestos-based gaskets are applied, for example, to exhaust manifolds in internal combustion engines such as engines. In automobile engines, exhaust gas reaches temperatures of 600 to 1000°C. Therefore, gaskets used in such exhaust manifolds are required to have heat resistance to maintain the required sealing performance even when exposed to such high temperatures for long periods of time.

Means for Solving the Problems The present invention uses a non-woven sheet made of ceramic fibers containing ceramic particles unevenly distributed.
This overcomes the above problems.

That is, the present invention provides a ceramic fiber sheet in which ceramic particles are unevenly distributed in a non-woven sheet made of ceramic fibers such that one side has a low content or no ceramic particles and the other side has a high content. The present invention provides a heat-resistant gasket characterized in that it is provided on both sides of a metal substrate with the high-content side facing inside.

By using functional ceramic fibers and ceramic particles,
A gasket having the necessary heat resistance can be obtained.

Further, by forming ceramic fibers into a nonwoven sheet, it is possible to form a ceramic fiber sheet in which the content of ceramic particles is unevenly distributed in the thickness direction. and,
By using a bendable sheet and providing it on a metal substrate with the side with a high content of ceramic particles inside, it is possible to achieve a ceramic fiber-rich surface (good contact surface sealing performance against the object to be sealed, and a ceramic fiber-rich surface). Improved sealing properties are achieved due to the reduction in porosity due to the inclusion of particles.

Example An example of the structure of the heat-resistant gasket of the present invention is shown in the figure.

This has a ceramic fiber sheet 1 provided on both sides of a metal substrate 2, and the ceramic fiber sheet 1 is made of a nonwoven sheet made of ceramic fibers 11 containing ceramic particles]2 unevenly distributed therein. The ceramic fiber sheets 1 on both sides of the metal substrate 2 are provided with the side with a higher content of ceramic particles 12 facing inside.

In the present invention, the smaller the content of ceramic particles in the surface layer of the ceramic fiber sheet, the more preferable it is from the viewpoint of sealability of the contact surface with respect to the object to be sealed. Therefore, it is preferable that the surface layer does not contain ceramic particles. On the other hand, in the interior, contrary to the above, the higher the content of ceramic particles, the greater the reduction in porosity in the tightened state with the cassette attached, which is preferable in terms of improving sealing performance.

The ceramic fiber sheet is formed by applying a known nonwoven fabric forming method, such as spreading a liquid in which ceramic fibers and ceramic particles are dispersed on a slippery table such as felt and removing the dispersion medium. It can be done by In that case, a state of uneven distribution of ceramic particles is formed based on the property of ceramic particles that settle more easily than ceramic fibers.

Any suitable ceramic fiber may be used depending on the intended use of the cassette. In the case of the exhaust system of the above-mentioned automobile engine, one having a heat resistance of 600° C. or higher is used. Typical examples include alumina fibers, silica fibers, alumina-silica fibers, zirconia fibers, glass fibers, rock wool, silicon carbide fibers, silicon nitride fibers, tunorsium silicate fibers, and potassium titanate fibers. Among them, alumina and silica fibers,
Zirconia fibers, glass fibers, etc. are preferably used. In addition, one or more types of non-glass fibers such as alumina/silica fibers, zirconia fibers, and alumina fibers,
It is preferable to use one kind or a combination of two or more kinds of glass fibers. In that case, the appropriate amount of glass fiber to be used is 10 to 100 parts by weight per 100 parts by weight of non-glass fibers. The ceramic fiber used has a thickness of 0.1 to 50u.
m, especially 1 to 30 um.

A length of 1 to 1.50 mm, especially 5 to 100 mm is suitable.

Appropriate ceramic particles may also be used. Generally, a material made of the above-mentioned ceramic fiber forming material is used. The amount of ceramic particles used may be determined as appropriate depending on the intended use of the gasket to be formed. Typically, 5 to 200 parts by weight per 100 parts by weight of ceramic fibers are used. The diameter of the ceramic particles to be used depends on the thickness of the cassette to be formed, but in general, it is suitably 0.1 to 0.5 mm, particularly 0.1 to 0.5 mm. In the present invention, ceramic particles (shot) produced as a by-product when forming ceramic fibers by a melt-spinning method can also be used. Conventionally, such shot was removed from the ceramic fiber mass as an impurity, but in the present invention, the shot-containing ceramic fiber mass can be directly used in the above-described nonwoven fabric forming method to form the desired ceramic fiber sheet. Therefore, shot, which has hitherto been removed as a harmful substance, can be effectively utilized as a useful ingredient, and its practical significance is particularly great.

When forming the ceramic fiber sheet, an inorganic binder, an organic binder, an organic polymer fiber, etc. may be used in combination, if necessary.

The inorganic binder is more effective in increasing heat resistance in sheet form, imparting good form retention, and improving durability against exhaust gas flow and the like. The inorganic binder used may be essentially inorganic, or may be organic in an uncured or semi-cured state;
It may be inorganic at the stage where it substantially acts as a binder. Examples of inorganic binders that can be used include various ceramicized silicones and silica-based solutions. Ceramized silicon includes, for example, CE
LA400 (product name, manufactured by Kansai Paint Co., Ltd.), AY4
9-208 (trade name, manufactured by Toshi Silicone Co., Ltd.), and silica-based solutions such as (Sumiceram PN2010, trade name,
manufactured by Asahi Chemical Industry Co., Ltd.). The amount of the inorganic binder used is preferably 300 parts by weight or less, particularly 30 to 200 parts by weight, per 1.00 parts by weight of the ceramic fibers. In addition,
The inorganic binder may be applied by pre-mixing with each component and spreading the mixture to form a sheet, or by forming a sheet using other ingredients and then applying the inorganic binder to this sheet. It may be applied by coating or impregnating.

Organic binders and organic polymer fibers are more effective in improving the form retention and flexibility of the formed sheet at room temperature, thereby improving handling properties. However, it is usually undesirable to use a large amount because it may burn out at high temperatures during practical use, which may cause a reduction in sealing performance. The amount of organic binder used is generally 10% by weight or less, especially 7% by weight or less, based on the total amount of the formed sheet. The amount of organic polymer fibers used is generally 1 to 30 parts by weight per 100 parts by weight of ceramic fibers, preferably 10% by weight or less, particularly 8% by weight or less, based on the total amount of the formed sheet. Note that it is more preferable to suppress the total amount of the organic binder and organic polymer fibers to 10% by weight or less based on the total amount of the formed sheet.

Examples of organic binders that can be used include NBR emulsion, acrylic emulsion, and polyvinyl alcohol aqueous solution. Examples of organic polymer fibers include synthetic fibers such as aromatic polyamide fibers, aromatic polyester fibers, phenol resin fibers, and carbon fibers, and natural fibers such as kraft pulp. The thickness of the fiber is 0.1 to 10 hm, especially 1 to 50 um, and the length is 0.1 to 10 hm.
A range of 1 to 30 mm, especially 0.5 to 10 mm, is suitable.

The ceramic fiber sheet to be used preferably has a basis weight of 0.90 kg/J or more from the viewpoint of sealing performance.

The thickness is appropriately determined depending on the intended use of the gasket to be formed. Generally, those having a thickness of 0.5 to 1.5 mm are used.

In addition to the above ingredients, the ceramic fiber sheet also contains
It may contain 5 to 50% by weight of inorganic fillers such as unexpanded vermiculite, expanded vermiculite, talc, clay, and mica.

As the metal substrate serving as the reinforcing material, a known material such as an iron plate may be used. In the embodiment, hooks 21 for locking are provided on both sides.
Although the metal substrate 2 having a hook is used, a metal substrate without a hook may be used. In this case, the ceramic fiber sheet is fixed to the metal substrate using an adhesive or the like.

By the way, the thickness is 1. , 9 um N average length 70 m
33 parts (parts by weight, same below)
, 27 parts of glass fiber (FES13, manufactured by Fuji Fiber Glass Co., Ltd.) with a thickness of 1.1.71 m% and an average length of 13 mm, 30 parts of alumina/silica shot with a particle size of 50 to 500 um,
5 parts of kraft pulp with a thickness of 50 J'm and an average length of 2 mm, expanded vermiculite (Hilcon S) with an average particle size of about 0.5 mm.
#80, manufactured by Hiruishi Kagaku Kogyo Co., Ltd.), 40 parts of a 5% by weight alum aqueous solution, and 5 parts of NBR emulsion (solid content) was spread on felt, and alumina-silica shot was applied in the thickness direction A sheet made of unevenly distributed ceramic fibers was obtained, which was pre-pressed at room temperature and then compressed with a roll to an average thickness of 1 mm.

A ceramic fiber sheet with a basis weight of 1 kg/Ilv was obtained.

When the ceramic fiber sheet is divided into three equal parts: a surface layer, a back layer, and an intermediate layer between them, the content of alumina/silicone shot in the ceramic fiber sheet is 5% by weight in the surface layer, 20% by weight in the intermediate layer, and 45% by weight in the back layer. %Met.

Next, the ceramic fiber sheets described above were applied to both sides of a steel plate with a thickness of 0.2 mm and hooks on both sides, with the high shot content side facing inside, and then a silica emulsion (Hamaceracon, (manufactured by Yokohama Rubber Co., Ltd.) to impregnate each portion with approximately 20 parts (solid content) to obtain a heat-resistant gasket in the form of a sujiru vest.

As a result of investigating the sealing properties of the heat-resistant gaskets mentioned above, 1.
It was 0 cc/min.

On the other hand, the sealing performance of a comparative gasket obtained according to the above example using 63 parts of alumina-silica fiber without adding alumina-silica shot was 7.
It was 0 cc/min.

In addition, in the sealing test, a donut-shaped gasket with an outer diameter of 90mm and an inner diameter of 74+mm was loaded with 300 kg/kg from both sides.
Tighten through a stainless steel flange at a pressure of cnt, heat the stainless steel flange together at 600℃ for 22 hours, cool it to room temperature, and blow air into the space inside the flange to reduce the internal pressure to 0.5 kg/cn? This was done by measuring the amount of air leakage from the mating surfaces of the flanges while holding the

Effects of the Invention The heat-resistant gasket of the present invention has excellent heat resistance because it is made of ceramic, and has excellent sealing performance because it contains ceramic particles, and also has excellent sealing performance at the interface with the object to be sealed due to its uneven distribution. It is also excellent.

[Brief explanation of drawings]

The figure is a sectional view of the embodiment. 1: Ceramic fiber sheet 11: Ceramic fiber 12: Ceramic particles 2 Metal substrate 21: Hook Patent applicant: Nippon Line Co., Ltd. Same day ago Mitsubishi Cable Industries Co., Ltd.

Claims (1)

[Claims] 1. A non-woven sheet made of ceramic fibers contains ceramic particles unevenly distributed so that one side has a low content or no ceramic particles and the other side has a high content. A heat-resistant gasket characterized by being provided on both sides of a metal substrate with the volume side facing inside.