JP3899286B2 - Sheet gasket - Google Patents

Description

【００３０】
表１に示す実験結果からも明らかなように、本発明の実施例品は、従来品４に比べて材料費及び加工費の低減により製品のコストダウンを図ることが可能であり、また、従来品１，２に比べて漏れ量の減少を図ることが可能であり、さらに、従来品２に比べて加圧成形時のずれがなくて全体のシール性能の著しい向上が図り得ることが確認できた。
【００３１】
なお、上記実施例では、円環状形のシートガスケットについて説明したが、四角環状形であってもよい。また、シート状基材の材料として、上記実施例では、膨張黒鉛や多孔質ＰＴＦＥを用いたが、これ以外に、ビータシート、ジョイントシートまたは抄造ペーパーような層状の内部構造を有する材料であればよい。
【００３２】
さらに、シートガスケットにおける高気密層に、例えば油や樹脂等の不浸透性物質を充填することにより、高密度層内の微少な隙間も不浸透性物質で塞いで流体の微少漏れも確実に防止し、シートガスケット全体のシール性能を一層高めることができる。
【００３３】
【発明の効果】
以上のように、本発明によれば、二種類の素材シートを各別に作製準備する必要がなく、内外方向に所定幅を有する一種類のシート状基材（素材シート）を作製し、その内外方向の中間部に傾斜スリットを形成した上で肉厚を揃えるために加圧成形すればよいので、材料費及び加工費の低減により製品のコストダウンを図ることができるとともに、スリットがシート状基材の厚み方向を横断してシート状基材が内外方向で複数個に分割されるような形態のものであっても、シート状基材表面に対して直角な溝や隙間を形成して内外方向で複数個のシート状基材に分割する従来品に比べて、分割シート状基材の継ぎ部分の強度低下がなく、ガスケット全体に亘って均一な強度を確保することができる。それでいて、内外方向の中間部分には基材表面に対して傾斜するスリットが形成されているので、加圧成形時の内外径方向への寸法変化を傾斜面のすべりで吸収するとともに、傾斜面に大きな加圧力を付与して高密度層を確実に形成してシート状基材の内部構造層を経て外部に至る浸透漏れの発生を著しく減少し、ガスケット全体としてのシール性能を十分に確保することができるという効果を奏する。
【００３４】
特に、厚み方向を横断して形成されるスリットの断面形状を＞形または略Ｘ形とする場合は、内外方向に分割されたシート状基材の内外端部分同士を互いに嵌合状態に保持して加圧成形することが可能で、内外の分割シート状基材の位置ずれがなく、両者を確実に一体化してガスケット本来のシール性能を一層高めることができる。
【図面の簡単な説明】
【図１】本発明の第１実施例によるシートガスケットの加圧成形前の平面図である。
【図２】図２は図１のＡ−Ａ線に沿った断面構造を示す要部の拡大斜視図である。
【図３】加圧成形後の要部の拡大縦断面図である。
【図４】第１実施例の変形断面構造の一つを示す要部の拡大斜視図である。
【図５】第１実施例の変形断面構造の他の一つを示す要部の拡大斜視図である。
【図６】本発明の第２実施例によるシートガスケットの断面構造を示す要部の拡大斜視図である。
【図７】本発明の第３実施例によるシートガスケットの要部の拡大縦断面図である。
【図８】本発明の第４実施例によるシートガスケットの要部の拡大縦断面図である。
【図９】従来品３のシートガスケットの加圧成形前の断面構造を示す要部の拡大斜視図である。
【図１０】従来品４のシートガスケットの加圧成形前の断面構造を示す要部の拡大斜視図である。
【図１１】従来品４のシートガスケットの加圧成形後の断面構造を示す要部の拡大縦断面図である。
【符号の説明】
１ シート状基材
１Ａ，１Ｂ 分割シート状基材部
２ スリット
３Ａ，３Ｂ，４ 高気密層
５ シートガスケツト[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet gasket used as a sealing material for various pipes, joints of pressure vessels, joints of fluid equipment, and the like, and in particular, leakage of fluids that are likely to cause osmotic leakage such as gas-based fluids. The present invention relates to a sheet gasket used for prevention.
[0002]
[Prior art]
Conventionally known sheet gaskets of this type include the following.
(1) A joint sheet gasket (hereinafter referred to as a conventional product 1) in which rubber and a filler are integrated into a sheet by a papermaking method or a hot roll method.
(2) As disclosed in Japanese Utility Model Application Publication No. 29097, Taisho 15th, the annular sheet-like base material has an annular shape at a right angle to the surface of the sheet-like base material. A sheet gasket (hereinafter referred to as conventional product 2) formed by providing a groove having a shape and filling the groove with an impervious substance.
(3) As disclosed in Japanese Patent Application Laid-Open No. 7-19342 and as shown in FIG. 9, annular divided sheet-like base materials 21 and 22 having different diameters are arranged concentrically inside and outside in the same plane, An impervious substance 24 such as a rubber-based or resin-based sealant or a resin adhesive is filled in a gap 23 perpendicular to the surface formed between the inner and outer peripheral surfaces of the two divided sheet-like base materials 21 and 22. A sheet gasket obtained by integrating both divided sheet-like base materials 21 and 22 (hereinafter referred to as conventional product 3).
(4) A layered internal structure such as expanded graphite or porous polytetrafluoroethylene (hereinafter referred to as porous PTFE) as disclosed in JP-A-7-217743 and as shown in FIG. The sheet-like base materials 21 and 22 that are formed of a material having an inner and outer direction and are partially overlapped with each other in the inner end portion 22A and the outer end portion 21A and the inner end portion 22A that are adjacent to each other in the inner and outer directions. By press-molding so that the entire wall thickness including the portion is substantially uniform, as shown clearly in FIG. A sheet gasket formed with the layer 25A (hereinafter referred to as a conventional product 4).
[0003]
[Problems to be solved by the invention]
Among the conventional sheet gaskets described above, the conventional product 1 can be used by applying a high tightening surface pressure, so that leakage from the contact surface can be suppressed or prevented. Therefore, even if it is used with a high clamping surface pressure applied, it is impossible to prevent the occurrence of permeation leakage to the outside through the layered structure.
[0004]
On the other hand, the conventional products 2 and 3 have an impervious substance in an intermediate portion in the inner and outer directions of the sheet-like base material, and the conventional product 4 has a high-density layer in the middle portion of the sheet-like base material. Compared with the product 1, it is possible to remarkably reduce the permeation leakage of the fluid passing through the layered internal structure and reaching the outer periphery of the base material. On the other hand, in the case of the conventional products 2 and 3, the inside and outside of the sheet-like base material Since grooves and gaps perpendicular to the surface are formed in the middle part of the direction, the strength of the joint part of the inner and outer sheet-like base material parts divided across the grooves and gaps decreases, and the entire sheet gasket In addition to not being able to ensure a uniform strength over time, the dimensions of the grooves and gaps are likely to expand with the dimensional change in the inner and outer diameter directions during pressure molding to equalize the wall thickness. The tightening surface pressure in the middle part will decrease and the leakage prevention performance will decrease. To easily impaired original sealing performance gasket sheet substrate portion of the inside and outside are easily separated from each other.
[0005]
Further, in the case of the conventional product 4, since it is necessary to prepare and prepare two kinds of material sheets, the inner and outer divided sheet-like base materials 21 and 22, each having an overlapping portion, the material cost and the processing cost are increased. The problem remains that the product cost is likely to rise.
[0006]
The present invention has been made in view of the above circumstances, and it is intended to reduce the product cost by using only one type of material sheet, and to ensure a uniform strength throughout the whole while significantly reducing the penetration leakage. An object of the present invention is to provide a sheet gasket capable of exhibiting high sealing performance.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a sheet gasket according to the present invention is formed on the surface of a sheet-like base material at an intermediate portion in the inner and outer directions of the sheet-like base material formed in an annular shape from a material having a layered internal structure. On the other hand, a slit inclined at about 30 to 50 ° is formed, and the whole sheet-like substrate including this inclined slit portion is pressure-formed so as to have a substantially uniform thickness, and a high airtight layer is formed in the intermediate portion. It is characterized by forming.
[0008]
As the slit in the sheet-like base material of the sheet gasket having the above configuration, a part of the base material remains connected without crossing the thickness direction of the sheet-like base material, and the high airtight layer is formed in the thickness direction of the gasket at the time of pressure molding. Even if it is formed to a depth that crosses the substrate, it is formed across the thickness direction of the sheet-like base material as in claim 2, and the inside and outside directions are divided by the transverse slit. You may make it a split sheet-like base material be integrated via a high airtight layer by making the inclined surfaces of a some split sheet-like base material mutually closely press-mold.
[0009]
The slit formed across the thickness direction of the sheet-like base material may be linear, and in particular, as in claim 3, the cross-sectional shape is> or substantially X-shaped. It is preferable that
[0010]
In addition, the highly airtight layer in the sheet gasket having the above-described configuration may be formed by increasing at least one of the orientation state and density of the material by pressure molding as described in claim 4. Most preferably, it should be formed in a high density and highly oriented state.
[0011]
Further, as a material for forming the sheet-like base material in the sheet gasket having the above-described configuration, as selected in claim 5, the material selected from expanded graphite, porous PTFE, beater sheet, joint sheet, or paper-made paper Is used.
[0012]
Furthermore, it is desirable that the highly airtight layer in the sheet gasket having the above-described configuration is filled with an impervious substance such as oil or resin as described in claim 6.
[0013]
According to the present invention having the above-described configuration requirements, the entire shape including the inclined slit portion formed in the intermediate portion in the inner and outer directions of the sheet-like base material is pressure-formed so as to have a substantially uniform thickness. Since a highly airtight layer that is inclined with respect to the substrate surface is formed at the intermediate portion in the inner and outer directions, the inclined slits cross the thickness direction of the sheet substrate and the sheet substrate is divided into a plurality in the inner and outer directions. Even in the form of being divided, compared to conventional products 2 and 3 that form grooves and gaps perpendicular to the substrate surface and divide into a plurality of sheet-like substrates in the inner and outer directions, It is possible to ensure a uniform strength over the entire gasket without lowering the strength of the joint portion of the divided sheet-like base material. Moreover, since one kind of sheet-like base material (material sheet) having a predetermined width in the inner and outer directions may be produced and an inclined slit may be formed in the middle part thereof, it is necessary to prepare and prepare two kinds of material sheets separately. Compared to a certain conventional product 3, material costs and processing costs can be reduced, and the cost of the product (sheet gasket) can be significantly reduced. Nevertheless, the internal structure of the sheet-like base material is formed by absorbing the dimensional change in the inner and outer diameter directions during pressure molding by slipping of the inclined surface and applying a large pressing force to the inclined surface to reliably form a high-density layer. It is possible to remarkably reduce the occurrence of permeation leakage to the outside through the layers and improve the sealing performance of the entire gasket.
[0014]
In particular, when the cross-sectional shape of the transverse slit is> or substantially X-shaped, the inner and outer end portions of the sheet-like base material divided in the inner and outer directions can be press-molded while being held in a fitted state. This is possible, and there is no positional deviation between the inner and outer divided sheet-like base materials, and both can be reliably integrated to further enhance the original sealing performance of the gasket.
[0015]
In addition, when filling an impermeable material such as oil or resin into a high-density layer, a minute gap in the high-density layer can be blocked with an impermeable material, and a minute fluid leak can be reliably prevented. .
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a plan view of a sheet gasket according to a first embodiment of the present invention before pressure molding, and FIG. 2 is an enlarged perspective view of a main part showing a cross-sectional structure taken along line AA of FIG.
[0017]
The sheet gasket 5 is formed by pressing a material having a layered internal structure such as expanded graphite or porous PTFE on an intermediate portion in the inner and outer directions of one kind of sheet-like base material 1 formed in an annular shape. As shown in FIG. 2, by forming the slit 2 having a cross-sectional shape of> shape over the entire circumference across the thickness direction of the sheet-like substrate 1, the annular sheet-like substrate 1. Is divided into two sheet-like base material portions 1A and 1B in the inner and outer directions, and the outer peripheral end portion 1a and the inner peripheral end portion 1b of the two divided sheet-like base material portions 1A and 1B are fitted to each other, The two divided sheet-like base portions 1A and 1B are integrated and formed by pressure-molding so that the entire inclined wall surfaces 1a1 and 1b1 are in close contact with each other and have a substantially uniform thickness. Has been.
[0018]
The sheet gasket 5 according to the first embodiment is formed by using one type of sheet-like base material 1 formed in an annular shape, forming a slit 2 in an intermediate portion in the inner and outer directions, and then performing pressure molding. It can be manufactured, and the cost of the product (sheet gasket) can be significantly reduced by reducing the material cost and the processing cost. And after press molding, as clearly shown in FIG. 3, high-density and highly-oriented air-tight layers 3A and 3B are formed over the entire inner and outer directions of both front and back surfaces of both divided sheet-like substrate portions 1A and 1B. In addition, a high-density, high-orientation highly airtight layer 4 inclined in a cross-sectional shape> shape with respect to the front and back surfaces of the sheet-like substrate 1 is formed in the middle portion in the inner and outer directions of the sheet-like substrate 1. ing.
[0019]
Therefore, for example, by interposing on the joint flange surface of the pipe and tightening to a high surface pressure via a bolt or the like, the high-density, highly-oriented airtight layers 3A, 3B of the sheet-like substrate 1 (1A, 1B) are used. Is in close contact with the joint flange surface to prevent contact surface leakage, while penetrating leakage extending radially outward through the layered internal structure of the sheet-like substrate 1 is formed in the intermediate portion in the inner and outer directions. The high airtight layer 4 is cut off. In addition, the fluid blocked by the highly airtight layer 4 having a cross-sectional shape of> is guided to the front surface or the back surface side of the sheet-like base material 1 along the highly airtight layer 4 and is in a state of contact surface leakage. Since the airtight layers 3A and 3B are present in this portion as described above, contact surface leakage does not occur due to changes from permeation leakage, and the sheet gasket 5 as a whole exhibits very high sealing performance. Can do.
[0020]
In addition, in the said 1st Example, it shows by what formed the cross-sectional shape> shape slit 2 and the high airtight layer 4 so that the vertex X may be located on the center part C of the thickness direction of the sheet-like base material 1. However, as shown in FIG. 4 or FIG. 5, the> -shaped slit 2 and the apex X of the highly airtight layer 4 are formed so as to be biased to one of the front side or the back side in the thickness direction of the sheet-like substrate 1. Also good. Moreover, it is desirable to set the inclination angle θ of the slit 2 with respect to the surface of the sheet-like substrate 1 to about 30 to 50 °. When the inclination angle θ is less than 30 °, slit processing is difficult, and when it exceeds 50 °, the opposing surfaces of the slits 2 do not adhere to each other at the time of pressure molding, and the bonding force between them is weak so that they are easily separated.
[0021]
FIG. 6 is an enlarged vertical perspective view of the main part of the seat gasket according to the second embodiment of the present invention. In the sheet gasket 5 according to the second embodiment, the cross-sectional shape of the slit 2 formed over the entire circumference of the sheet-like base material 1 across the thickness direction of the sheet-like base material 1 at the intermediate portion in the inner and outer directions. The second embodiment is different from the first embodiment in that it is formed in a substantially X shape, and the other configurations are the same as those in the first embodiment. Therefore, the corresponding parts are denoted by the same reference numerals, and detailed descriptions thereof are omitted. .
[0022]
Similarly to the sheet gasket according to the first embodiment, the sheet gasket 5 according to the second embodiment uses a single sheet-like base material 1 formed in an annular shape, and has a substantially X-shaped intermediate portion in the inner and outer directions. After forming the slit 2 in the shape, it can be manufactured by pressure molding, and the cost of the product (sheet gasket) can be significantly reduced by reducing the material cost and the processing cost. Then, high-density and highly-oriented air-tight layers 3A and 3B are formed over the entire inner and outer directions of the front and back double-sided portions of both divided sheet-like base materials 1A and 1B by pressure molding. A substantially X-shaped high-density, high-orientation highly airtight layer 4 is formed in the middle portion in the direction along the transverse slit 2 having a substantially X-shaped cross section. In addition to being excellent in prevention performance, it is also possible to prevent the permeated fluid from being guided to the front or back side of the sheet-like base material 1 and converted to contact surface leakage. The sealing performance can be further enhanced.
[0023]
FIG. 7 is an enlarged longitudinal sectional view of the main part of the seat gasket according to the third embodiment of the present invention. In the sheet gasket 5 according to the third embodiment, a linear slit 2 inclined with respect to the surface of the sheet-like base material 1 is provided in the middle portion in the inner and outer directions of the sheet-like base material 1 in the thickness direction of the sheet base material 1. The second embodiment is different from the first embodiment in that it is formed so as to cross, and the other configuration is the same as that of the first embodiment. Therefore, the same reference numerals are given to the corresponding portions, and detailed description thereof is omitted.
[0024]
Similarly to the sheet gaskets according to the first and second embodiments, the sheet gasket 5 according to the third embodiment uses one kind of sheet-like base material 1 and has a substantially X-shaped slit 2 at an intermediate portion in the inner and outer directions. Can be manufactured by pressure molding, reducing material costs and processing costs, and significantly reducing the cost of products (sheet gaskets), and inclining linearly in the inner and outer directions Since the high-density, highly-oriented high hermetic layer 4 is formed, sufficient permeation leakage prevention performance can be exhibited.
[0025]
FIG. 8 is an enlarged longitudinal sectional view of a main part of a sheet gasket according to a fourth embodiment of the present invention. In the sheet gasket 5 according to the fourth embodiment, the sheet is formed at an intermediate portion in the inner and outer directions of the sheet-like substrate 1. The second embodiment is different from the first embodiment in that a slit 2 having a substantially C-shaped cross section is formed which remains part of the substrate 1 connected without crossing the thickness direction of the substrate 1. Since it is the same as that of an example, the same code | symbol is attached | subjected to a corresponding part and those detailed description is abbreviate | omitted.
[0026]
In the case of the sheet gasket 5 according to the fourth embodiment, the entire sheet including the slit 2 portion having a substantially C-shaped cross section is pressure-formed so as to have a uniform thickness, so that the sheet is formed in the intermediate portion in the inner and outer directions. A highly hermetic layer having a substantially cross-sectional shape that crosses continuously in the thickness direction of the gasket 5 is formed, and it is possible to exhibit substantially the same permeation leakage prevention performance as in the first embodiment. is there.
[0027]
Any one of the above-described sheet gaskets of the first to fourth embodiments of the present invention may be prepared by forming one kind of sheet-like base material 1 and forming an inclined slit 2 in the middle thereof, followed by pressure molding, Compared to the conventional product 3, which requires two types of material sheets to be prepared separately, the material cost and processing cost can be reduced, and the cost of the product (sheet gasket) can be significantly reduced. Compared to the conventional products 2 and 3 in which grooves and gaps perpendicular to each other are formed and divided into a plurality of sheet-like substrates in the inner and outer directions, there is no reduction in strength of the joint portions of the divided sheet-like substrates 1A and 1B, It is possible to ensure a uniform strength over the entire gasket 5. Nevertheless, the dimensional change in the inner and outer diameter directions during pressure molding is absorbed by the slip of the inclined surface, and a large pressure is applied to the inclined surface, so that the high-density layer 4 is reliably formed. The occurrence of permeation leakage to the outside through the internal structure layer of the material 1 can be significantly reduced, and the sealing performance of the entire gasket 5 can be enhanced.
[0028]
Incidentally, the present inventors, among the embodiments of the present invention, the leakage amount and the division at the time of pressurization for the seat gaskets of the first embodiment and the second embodiment and the seat gaskets of the conventional products 1, 2, 4 respectively. Experiments were conducted to confirm the presence or absence of displacement of the sheet-like substrate parts 1A and 1B, and the results shown in Table 1 were obtained.
[0029]
[Table 1]

[0030]
As is apparent from the experimental results shown in Table 1, the product according to the embodiment of the present invention can reduce the cost of the product by reducing the material cost and the processing cost as compared with the conventional product 4, and the conventional product can be reduced. It is possible to reduce the amount of leakage compared to products 1 and 2, and it can be confirmed that there is no shift during pressure molding compared to conventional product 2 and the overall sealing performance can be significantly improved. It was.
[0031]
In the above embodiment, an annular seat gasket has been described. However, a square annular shape may be used. Moreover, in the said Example, although the expanded graphite and porous PTFE were used as a material of a sheet-like base material, if it is a material which has a layered internal structure like a beater sheet, a joint sheet, or papermaking paper other than this, Good.
[0032]
Furthermore, by filling the airtight layer of the seat gasket with an impervious material such as oil or resin, the minute gaps in the high-density layer are closed with the impervious material, and the fluid is surely prevented from leaking. In addition, the sealing performance of the entire sheet gasket can be further enhanced.
[0033]
【The invention's effect】
As described above, according to the present invention, it is not necessary to prepare and prepare two kinds of material sheets separately, and one kind of sheet-like base material (material sheet) having a predetermined width in the inner and outer directions is produced. Since it is sufficient to form an inclined slit in the middle of the direction and then press-molding to make the thickness uniform, the cost of the product can be reduced by reducing the material cost and processing cost, and the slit is Even if the sheet-like base material is divided into a plurality of parts in the inner and outer directions across the thickness direction of the material, grooves and gaps perpendicular to the surface of the sheet-like base material are formed to form an inner and outer surface. Compared to a conventional product that is divided into a plurality of sheet-like base materials in the direction, the strength of the joint portion of the divided sheet-like base materials is not reduced, and uniform strength can be ensured over the entire gasket. Still, since the slits that are inclined with respect to the substrate surface are formed in the intermediate portion in the inner and outer directions, the dimensional change in the inner and outer diameter directions during pressure molding is absorbed by the slip of the inclined surface, and the inclined surface Giving a large pressing force to reliably form a high-density layer, significantly reducing the occurrence of permeation leakage to the outside through the internal structure layer of the sheet-like substrate, and ensuring sufficient sealing performance as a whole gasket There is an effect that can be.
[0034]
In particular, when the cross-sectional shape of the slit formed across the thickness direction is> or substantially X-shaped, the inner and outer end portions of the sheet-like base material divided in the inner and outer directions are held in a fitted state. Thus, the inner and outer divided sheet-like base materials are not misaligned, and the two can be reliably integrated to further enhance the original sealing performance of the gasket.
[Brief description of the drawings]
FIG. 1 is a plan view of a sheet gasket according to a first embodiment of the present invention before pressure molding.
FIG. 2 is an enlarged perspective view of a main part showing a cross-sectional structure along the line AA in FIG. 1;
FIG. 3 is an enlarged longitudinal sectional view of a main part after pressure molding.
FIG. 4 is an enlarged perspective view of a main part showing one of the modified sectional structures of the first embodiment.
FIG. 5 is an enlarged perspective view of an essential part showing another one of the modified sectional structure of the first embodiment.
FIG. 6 is an enlarged perspective view of a main part showing a cross-sectional structure of a seat gasket according to a second embodiment of the present invention.
FIG. 7 is an enlarged longitudinal sectional view of a main part of a seat gasket according to a third embodiment of the present invention.
FIG. 8 is an enlarged longitudinal sectional view of a main part of a seat gasket according to a fourth embodiment of the present invention.
FIG. 9 is an enlarged perspective view of a main part showing a cross-sectional structure of a conventional product 3 before pressure molding of a sheet gasket.
FIG. 10 is an enlarged perspective view of a main part showing a cross-sectional structure of the conventional product 4 before the pressure molding of the sheet gasket.
FIG. 11 is an enlarged longitudinal sectional view of a main part showing a sectional structure after pressure forming of a sheet gasket of a conventional product 4;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sheet-like base material 1A, 1B Division | segmentation sheet-like base-material part 2 Slit 3A, 3B, 4 High airtight layer 5 Sheet gasket

Claims (6)

A slit inclined at about 30 to 50 ° with respect to the surface of the sheet-like base material is formed in an intermediate portion in the inner and outer directions of the sheet-like base material formed in an annular shape from a material having a layered internal structure. A sheet gasket characterized in that a highly airtight layer is formed in the intermediate portion by pressure forming the entire sheet-like substrate including the inclined slit portion so as to have a substantially uniform thickness.   The slit is formed across the thickness direction of the sheet-like base material, and pressure forming is performed by bringing the inclined surfaces of the plurality of divided sheet-like base materials into close contact with each other in the inner and outer directions divided by the transverse slit. The sheet gasket according to claim 1, wherein the divided sheet-like base material is integrated through a highly airtight layer.   The sheet gasket according to claim 2, wherein a slit that crosses the thickness direction of the sheet-like substrate is formed to have a cross-sectional shape> shape or a substantially X-shape.   The sheet gasket according to any one of claims 1 to 3, wherein the highly airtight layer is formed by increasing at least one of an orientation state and a density of a material.   The sheet according to any one of claims 1 to 4, wherein the material forming the sheet-like base material is selected from expanded graphite, porous polytetrafluoroethylene, a beater sheet, a joint sheet, and paper-made paper. gasket.   The sheet gasket according to any one of claims 1 to 5, wherein the highly airtight layer is filled with an impermeable substance.

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