JP2010169102A - Annular gasket and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an annular gasket having characteristics required according to a medium to be sealed, and having a firmly connected connection. <P>SOLUTION: The annular gasket 1A is annularly molded by overlapping two or more elastic members 20, 30 having different characteristics in the radial direction to seal the medium 10 to be sealed. Two or more string-like uncrosslinked elastic materials with different characteristics are disposed in parallel in the radial direction in the annular die, and then heated and crosslinked respectively. Both ends of the elastic material have a connected part 4 with the elastic materials integrally formed with each other and disposed in the side of the medium to be sealed by the crosslinking. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an annular gasket that is interposed on a joint surface between two members and used to seal a medium to be sealed, and a manufacturing method thereof, for example, an intake manifold and a cylinder head cover of an engine mounted on an automobile or the like The present invention relates to an annular gasket interposed between the joint surfaces of a mounting member such as a mating member and a mating member thereof, and a method for manufacturing the same.

  An annular gasket formed in accordance with the shape of the joining surface is interposed on the joining surface as described above, and by fastening the joining surfaces, the annular gasket is pinched to seal the medium to be sealed. Such an annular gasket is conventionally known to be made from only a single material, but in this case, since it depends on the characteristics of only a single material, it is not a material with resistance to the medium to be sealed. In such a case, there is a problem that the sealing performance is lowered due to deterioration of the gasket over time. Further, when an almighty material that can maintain a good sealing property regardless of the joining surface is used, there is a concern that the cost may increase.

Then, the following patent document 1 and the following patent document 2 are mentioned as what coated the outer peripheral surface of the gasket with the raw material according to a sealing object medium.
Patent Document 1 below describes a sealing material in which a core material made of either organic fiber or metal is covered with an elastic body. According to this, it is said that the permeability of carbon dioxide gas can be effectively reduced by covering the core having low carbon dioxide permeability with an elastic material. Further, here, it is described that both ends of a linear member serving as a core are heated and melted, and both ends are butted and joined to form an annular body.
Further, in Patent Document 2 below, a core material composed of a block copolymer of vinylidene fluoride / hexafluoropropylene copolymer and ethylene / tetrafluoroethylene copolymer is made from a fluororesin having a thickness of 0.1 to 50 μm. A sealing material made of fluororesin-coated rubber coated with an outer layer is described. According to this, since the core material is coated with a fluororesin excellent in heat resistance, oil resistance, etc., it is possible to provide a sealing material having excellent non-adhesiveness while maintaining the elasticity unique to rubber. It is supposed to be possible. In addition, here, it is described that the inner core and the outer layer are extruded simultaneously by two-layer extrusion molding, and this is bent and both ends are fused to form an annular body.

JP 2005-188710 A JP 2005-344038 A

However, in the case of the gasket formed by coating the core material as described above, there is a concern about the followability and tearing of the coated layer.
Further, the above is not applicable when, for example, one gasket has a side where oil resistance is required and a side where sag resistance is required. That is, in an annular gasket used for an intake system of an automobile engine, a fuel oil resistance is required on the side of the medium to be sealed exposed to the medium to be sealed, and a sag resistance is required on the side of the medium to be sealed that is not exposed to the medium to be sealed. As described above, the sealing characteristics required for one annular gasket may differ.

Therefore, it is conceivable to produce a gasket using materials having different characteristics depending on the medium to be sealed.
However, for example, when an annular gasket is produced using an unvulcanized rubber material, both ends of the unvulcanized rubber material are abutted and joined together to vulcanize the two together. However, it has been pointed out that joining of unvulcanized rubber materials having different characteristics makes the joints fragile.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an annular gasket having characteristics required in accordance with a medium to be sealed and having a firmly joined joint.

  An annular gasket according to the first aspect of the present invention is an annular gasket for sealing a medium to be sealed, which is formed by annularly molding two or more kinds of elastic materials having different characteristics in the radial direction, and having different characteristics. Two or more types of uncrosslinked string-like elastic material are placed in parallel in the radial direction in an annular mold, heated and cross-linked, and both ends of the elastic material are cross-linked The elastic material materials arranged on the side of the medium to be sealed are joined together in an integrated state.

In the present invention, as in the invention of claim 2, two or more kinds of the elastic material materials arranged in the mold may be combined in advance.
According to this, since it is only necessary to arrange the elastic material material that has been combined and integrated in advance at a predetermined position in the mold, manufacturing is facilitated.

Further, as in the invention of claim 3, the elastic material is composed of the two kinds of elastic materials, and is arranged on the sealing target medium side so that the other elastic material (on the anti-sealing target medium side) is surrounded. It is good also as what is united.
According to this, since the other elastic material is integrally surrounded by the elastic material arranged on the sealing target medium side, the elasticity arranged on the other (anti-sealing target medium side) on the sealing target medium side. The material does not appear, and the characteristics of the elastic material arranged on the sealing target medium side can be surely exhibited. That is, if the elastic material arranged on the other side is surrounded by the elastic material arranged on the other side, the elastic material that should be arranged on the other side by compression during molding Does not appear on the elastic material side arranged on the sealing target medium side. Therefore, for example, when gas sealability is required on the side of the medium to be sealed, an elastic material having gas sealability is provided on the side of the medium to be sealed, and the elastic material disposed on the side of the medium to be sealed is surrounded by this elastic material. By doing so, an elastic material having gas sealing properties is surely filled on the medium to be sealed, and a desired annular gasket can be produced. Further, by arranging an elastic material corresponding to the performance required for the annular gasket on the sealing target medium side or the anti-sealing target medium side, it is possible to improve the performance of the annular gasket.

Further, as in the invention of claim 4, the elastic material on the medium side to be sealed can be made of fluoro rubber (FKM), and the elastic material on the other side (anti-sealing medium side) can be made of silicone rubber (VMQ). .
According to this, since fluoro rubber is used as the elastic material on the medium side to be sealed, the side of the medium to be sealed is fuel oil-resistant, gas-sealable, refrigerant-resistant, acid-resistant, and low-temperature properties utilizing the characteristics of the fluororubber. An annular gasket having sag resistance can be configured. Since the silicone rubber is used as the other elastic material, an annular gasket having sag resistance can be configured.
In addition, fluororubber is a relatively expensive material, and an inexpensive silicone rubber is placed on the anti-sealable medium side, so that the entire annular gasket is made of only fluororubber. The cost can be reduced while maintaining the above.

As in the invention of claim 5, two or more types of uncrosslinked string-like elastic material having different characteristics are arranged in parallel in the radial direction in the mold, and the seal is formed at both ends of the elastic material. It is possible to manufacture an annular gasket integrally formed by causing the elastic material materials on the target medium side to face each other and heating and crosslinking in this state.
According to this, the above-mentioned annular gasket can be produced by a simple manufacturing method.

In the annular gasket according to the present invention, the joint where the both ends of the elastic material are joined is formed by heat compression molding in a state where the elastic materials arranged on the medium side to be sealed are joined together. Therefore, it is possible to strengthen the joint state of the joint portion that tends to be fragile. Therefore, it is possible to prevent the sealing performance from deteriorating from the joint portion and causing leakage.
Moreover, since it consists of 2 or more types of elastic materials from which a characteristic differs, the material suitable for each of the sealing object medium side and the anti-sealing object medium side can be selected.
Therefore, depending on how the materials are combined, a high-performance annular gasket can be formed, and if inexpensive materials are combined, the cost of the gasket can be reduced.

It is a schematic plan view which shows one Embodiment of the annular gasket of this invention. (A) is the XX arrow directional cross-sectional view in FIG. 1, (b) is the YY arrow directional cross-sectional view in FIG. It is sectional drawing which shows the example in which the same annular gasket was interposed between the joining surfaces. It is the schematic plan view which showed the modification of the annular gasket. It is the schematic plan view which showed another modification of the same annular gasket. The 2nd Embodiment of the same annular gasket is shown, (a) is a figure equivalent to the XX arrow directional cross-sectional view in FIG. 1, (b) is the YY arrow directional cross-sectional view in FIG. It is an equivalent figure. (A) (b) is sectional drawing which shows the manufacturing process of the annular gasket in 2nd Embodiment shown in FIG. The modification of 2nd Embodiment of the same annular gasket is shown, Fig.8 (a) is a figure equivalent to the XX arrow sectional drawing in FIG. 1, FIG.8 (b) is Y- in FIG. It is a figure equivalent to a Y line arrow sectional view.

  Embodiments of the present invention will be described below with reference to the drawings. 1 is a schematic plan view showing an embodiment of an annular gasket of the present invention, FIG. 2 (a) is a sectional view taken along line XX in FIG. 1, and FIG. 2 (b) is a line YY in FIG. 3 is a cross-sectional view showing an example in which the same annular gasket is interposed between joint surfaces, FIG. 4 is a schematic plan view showing a modified example of the annular gasket, and FIG. FIG. 6 shows a second embodiment of the annular gasket, and FIG. 6A corresponds to a cross-sectional view taken along line XX in FIG. FIGS. 6A and 6B are views corresponding to the cross-sectional view taken along the line YY in FIG. 1, and FIGS. 7A and 7B show the manufacturing process of the annular gasket in the second embodiment shown in FIG. Sectional drawing and FIG. 8 have shown the modification of 2nd Embodiment of the same annular gasket, Fig.8 (a) is the XX arrow in FIG. View corresponding to a cross-sectional view, FIG. 8 (b) is a view corresponding to Y-Y cross sectional view taken along line in FIG.

(First embodiment)
First, an annular gasket 1A according to a first embodiment of the present invention will be described with reference to FIGS.
The annular gasket 1A is formed by annularly molding two types of elastic materials 20 and 30 having different characteristics in a radial direction, and seals the medium 10 to be sealed.
The annular gasket 1 </ b> A is attached to a groove portion 7 formed in the cover member 5 in order to seal between the joint surfaces of the cover member 5 (attachment member) and the counterpart member 6 in the cylinder head cover in the automobile engine. The annular gasket 1A is clamped by fastening with the mating member 6 (see the white arrow d in FIG. 3), and the medium 10 to be sealed is sealed.
Here, the side exposed to the medium to be sealed 10 is the medium to be sealed 2, the side not exposed to the medium to be sealed 10 is the anti-sealing medium side 3, the elastic material disposed on the medium to be sealed 2 is 20, The elastic material arranged on the target medium side 3 will be described with reference numeral 30.

FIG. 2A is a cross-sectional view taken along the line XX in FIG. 1. As shown here, the elastic material 20 arranged on the sealing target medium side 2 of the annular gasket 1A and the anti-sealing target medium side 3 are shown. An elastic material having different characteristics from the elastic material 30 to be arranged is used. Note that an adhesive may be inserted between the two types of elastic materials 20 and 30 having different characteristics to firmly bond them together.
For example, if the elastic material 20 on the sealing target medium side 2 is made of fluoro rubber (FKM) and the elastic material 30 on the anti-sealing target medium side 3 is made of silicone rubber (VMQ), the sealing target medium side 2 is utilized taking advantage of the characteristics of the fluoro rubber. Can constitute an annular gasket 1 having fuel oil resistance, gas sealability, refrigerant resistance, acid resistance, low temperature resistance, and sag resistance. Moreover, since the silicone rubber is used for the anti-seal target medium side 3, an annular gasket 1A having sag resistance can be configured.

The combination of the elastic members 20 and 30 disposed on the sealing target medium side 2 and the anti-sealing target medium side 3 is not limited to the above-described combination, and a hydrogenated acrylonitrile butadiene rubber ( Any combination of H-NBR), acrylic rubber (ACM), nitrile rubber (NBR), ethylene propylene rubber (EPDM), ethylene acrylic rubber (AEM), fluorosilicone rubber (FVMQ), and the like can be used. Moreover, it is not limited to two types of elastic materials having different characteristics, but may be a ring formed by combining two or more types of elastic materials.
Here, the elastic materials 20 and 30 are not limited to the rubber material described above, and may be an elastic compound material or a synthetic resin material in which compressive fibers such as glass fibers and ceramic fibers are mixed.

2B is a cross-sectional view taken along line YY in FIG. 1. As shown here, the joint 4 where both ends of the elastic members 20 and 30 of the annular gasket 1 are joined is to be sealed. The elastic members 20 arranged on the medium side 2 are joined together.
Since the annular gasket 1A shown in FIG. 1 is in a state in which the elastic members 20 are joined together, both end portions to be the joint portions 4 are bent and extended to the anti-seal target medium side 3 so as to protrude.
Thus, since the joining part 4 is joined by the elastic materials 20 which consist of the same material, it can join integrally, without making a boundary in a joining part by vulcanization | cure.
Therefore, since the gasket is annular, the joint state of the joint portion 4 that tends to be brittle can be strengthened. Further, by setting the elastic members 20 arranged on the sealing target medium side 2 to each other, the elastic member 30 arranged on the anti-sealing target medium side 3 appears on the sealing target medium side 2 at the joining portion 4. There is no, and it can be set as a good sealing property.

Next, the manufacturing procedure of the annular gasket 1A will be described. Here, the case where fluorine rubber (FKM) and silicone rubber (VMQ) are used as the elastic members 20 and 30, respectively, will be described.
First, an unvulcanized fluororubber composition is extruded and injected in a string form from the inner peripheral side (sealing target medium side 2) in the cavity of a mold (not shown) formed in a predetermined annular shape. Although the shape of the mold is not illustrated, the cavity of the mold is on the anti-sealing target medium side so that both ends of the unvulcanized string-like fluororubber composition are extended to the anti-sealing target medium side 3 and joined. The part which protruded to 3 is formed, and it inject | pours so that unvulcanized fluororubber compositions may be joined in the cavity of this protruded part. Then, an unvulcanized silicone rubber composition is extruded and injected into the outer peripheral side (anti-seal target medium side 3) in a string shape. The silicone rubber composition may be injected along the outer peripheral side of the string-like fluororubber composition already injected into the cavity. If it carries out like this, an unvulcanized fluororubber composition and a silicone rubber composition can be arrange | positioned in an annular metal mold | die respectively in parallel with radial direction. At this time, if the injection amount of the string-like fluororubber composition and the silicone rubber composition is substantially the same, the medium to be sealed at the substantially center as shown in FIG. An annular gasket 1A having different constituent materials can be formed on the side 2 and the anti-sealing medium side 3.
And if the fluororubber composition arrange | positioned at the sealing object medium side 2 is joined, heating and pressurizing for a predetermined time, vulcanization-molding and demolding will obtain the annular gasket 1A shown in FIG. it can.

  In the annular gasket 1A shown in FIG. 1, the joint 4 protrudes toward the medium 3 to be sealed, but this protruding portion is unnecessary or obstructed depending on the place where the annular gasket 1A is interposed. In this case, a circular annular gasket can be obtained by cutting along the two-dot chain line L. Further, the injection amount of the elastic material (in the above example, the fluororubber composition and the silicone rubber composition) is not limited to the above, but the injection amount of the dominant material (the fluororubber composition in the above example) By adjusting the material distribution by increasing or decreasing the number, it can be adapted to the place where the annular gasket 1A is interposed. Furthermore, the order of injecting the elastic material into the mold cavity is not limited to the above, and the elastic material on the anti-sealing target medium side 3 may be injected into the mold first.

According to the above, the joining portion 4 can be firmly joined and integrated without using an adhesive by a simple manufacturing method, and between two types of rubber materials (a fluororubber composition and a silicone rubber composition). It can be firmly joined and integrated. Of course, an adhesive may be interposed between the two rubber materials so that the rubber materials can be joined more firmly.
Moreover, since the combination of two or more kinds of elastic materials is not limited as described above, the elastic material material disposed in the mold is not limited to the above example, and is made of synthetic resin materials. It may be a thing. Therefore, when a material that is difficult to be bonded by vulcanization or crosslinking is used by a combination of elastic materials, an adhesive may be interposed.
Two or more types of elastic material may be combined in advance.
According to this, since it is only necessary to arrange the elastic material material that has been combined and integrated in advance at a predetermined position in the mold, the manufacture becomes even easier.

FIG. 4 is a schematic plan view showing an annular gasket 1B which is a modification of the above-described annular gasket 1A.
The annular gasket 1 </ b> B shown here is different in that it includes a plurality of joints 4, and FIG. 4 shows an example in which two joints 4 are provided. The joining method and joining state of the joining part 4 are the same as those of the above-described annular gasket 1A.
According to this, even when a plurality of the joint portions 4 are provided, the joint portions 4 are firmly joined, so that it is possible to prevent the sealing performance from deteriorating from the portion of the joint portions 4 and causing leakage.
Since other structures and effects are the same as those of the annular gasket 1A, the description thereof is omitted.

FIG. 5 is a schematic plan view showing an annular gasket 1C which is still another modified example of the above-described annular gasket 1A.
The annular gasket 1C shown here is different in that the joint 4 does not protrude like the annular gasket 1A shown in FIG.
In this case, since the protruding portion is not formed, the joint 4 is formed by using the elastic material on the sealing target medium side 2 and the end of the elastic material on the anti-sealing target medium side 3 during molding. It arrange | positions so that it may cover, and it heat-press-molds in the state which joined the elastic material materials arrange | positioned at the sealing object medium side 2, and forms the annular gasket 1C.
Therefore, in this case, the anti-seal target medium is provided with a space S (see FIG. 5) so that the elastic material material on the seal target medium side 2 is disposed in the part to be the joint part 4 in the cavity of the mold. If the elastic material on the side 3 is placed first and then the elastic material on the medium to be sealed 2 is injected, the annular gasket 1C shown in FIG. 5 can be easily formed.
Even if the joining portion 4 does not necessarily protrude, if the end portion 30 a of the elastic material 30 on the anti-sealing target medium side 3 is covered with the elastic material 20 on the sealing target medium side 2 in the joining portion 4 in this manner, The bonding strength can be the same as that of the above-described annular gasket 1A. Therefore, without preparing a new mold having a protruding portion, it is possible to produce an annular gasket 1 </ b> C having a joint portion 4 joined with strength by using a conventional mold.
Since other structures and effects are the same as those of the annular gasket 1A, the description thereof is omitted.

(Second Embodiment)
Next, an annular gasket 1D according to a second embodiment of the present invention will be described with reference to FIGS. Portions common to the first embodiment are denoted by common reference numerals, and description of the common portions is omitted.
The annular gasket 1D uses two kinds of elastic materials, and is formed so that the elastic material 20 arranged on the medium side 2 to be sealed surrounds the elastic material 30 arranged on the medium side 3 to be sealed. It will be.
FIG. 6A is a view corresponding to the cross-sectional view taken along the line XX in FIG. 1, and as shown here, an elastic material 20 disposed on the medium to be sealed 2 side of the annular gasket 1D, and an anti-seal object An elastic material having a characteristic different from that of the elastic material 30 disposed on the medium side 3 is used. In the annular gasket 1D having a square cross section, the elastic material 30 is disposed at a corner of the medium side 3 to be sealed, and the elastic material 30 is sealed. The target medium side 2 is surrounded by an elastic material 20 disposed on the seal target medium side 2.
Therefore, the characteristic of the elastic material 20 arrange | positioned at the sealing object medium side 2 can be exhibited reliably.

For example, when a high gas sealing property is required for the sealing target medium side 2, fluorine rubber having a high gas sealing property is arranged as the elastic material 20 on the sealing target medium side 2, and the elastic material 30 on the anti-sealing target medium side 3. Is surrounded by the elastic material 20, most of the annular gasket 1D is made of fluororubber, so that it is possible to obtain an annular gasket 1D having a high gas sealing property by taking advantage of its characteristics.
In addition, fluororubber is a relatively expensive material. According to this, if an inexpensive elastic material is disposed on the anti-seal target medium side 3 as compared with the case where the entire annular gasket is made of only fluororubber, Cost reduction can be achieved.

As shown in FIG. 6 (b), the joint portion 4 is joined by the elastic members 20 made of the same material, so that the joint portion can be joined together without any boundary at the joint portion by vulcanization.
Therefore, since the gasket is annular, the joint state of the joint portion 4 that tends to be fragile can be strengthened as in the first embodiment.

7 (a) and 7 (b) are cross-sectional views showing the manufacturing process of the annular gasket 1D in the second embodiment shown in FIG.
In the figure, 100A is a lower mold, 100B is an upper mold, C is a cavity formed in the lower mold 100A, 200 is an uncrosslinked elastic material disposed on the medium 2 to be sealed, and 300 is an anti-seal The uncrosslinked elastic material material disposed on the target medium side 3 will be described as the elastic materials 20 and 30.
First, the uncrosslinked elastic material 300 is extruded and injected into the outer peripheral side (anti-sealing target medium side 3) in the cavity C of the lower mold 100A formed in a predetermined annular shape. At this time, the injection amount of the elastic material 300 to be injected is injected along the outer peripheral corner of the cavity C so as to be surrounded by the elastic material 200 to be injected later.
Next, uncrosslinked elastic material is extruded and injected into the inner peripheral side (sealing target medium side 2) in a string shape. After being compressed as shown in FIG. 7A, about 2/3 (FIG. 7B) is injected so as to become the elastic material 20 on the inner peripheral side, that is, the medium to be sealed 2. Although the shape of the cavity C of the entire lower mold 100A is not shown here, the cavity C is an anti-sealing target so that both ends of the uncrosslinked elastic material are extended to the anti-sealing target medium side 3 and joined. A protruding portion is formed on the medium side 3, and the uncrosslinked elastic material 200 is injected into the cavity C of the protruding portion so as to be joined.
Then, in a state where the elastic material materials 200 disposed on the medium side 2 to be sealed are bonded together at the bonding portion 4, heating and pressing are performed for a predetermined time to perform vulcanization molding and demolding to obtain an annular gasket 1D. it can.

Note that the annular gasket 1D also has the joint 4 projecting toward the anti-sealing medium side 3, but if this projecting portion is unnecessary or obstructs, it may be removed.
The order of injecting the elastic material into the cavity C of the lower mold 100A is not limited to the above.

Thus, even if the elastic material 30 arranged on the anti-sealing medium side 3 is surrounded by the elastic material 20 arranged on the medium side 2 to be sealed, it can be easily manufactured and formed in this way. If this is done, the elastic material 30 that should be disposed on the anti-seal target medium side 3 due to compression during molding does not appear on the elastic material 20 side disposed on the seal target medium side 2.
In addition, also in the annular gasket 1D of the second embodiment, the example provided with the plurality of joint portions 4 shown in the first embodiment (FIG. 4) and the example where the joint portions 4 do not protrude (FIG. 5) are applied. can do.

8 (a) and 8 (b) are views showing an annular gasket 1E which is a modification of the above-described annular gasket 1D.
The annular gasket 1E shown here is the above-mentioned in that the elastic material 30 disposed on the anti-seal target medium side 3 is surrounded by the elastic material 20 disposed on the seal target medium side 2 in a substantially U-shaped cross section. Different from the annular gasket 1D.
How the elastic material 20 arranged on the medium side 2 to be sealed surrounds the elastic material 30 arranged on the medium side 3 to be sealed is not limited to the illustrated example. What is necessary is just to be comprised so that the elastic materials 20 and 30 which have the characteristic desired in a suitable place according to the place where 1E is interposed may be arrange | positioned.
Since other structures and effects are the same as those of the annular gasket 1A, the description thereof is omitted.

  In addition, if the cyclic | annular gaskets 1A-1E are cyclic bodies provided with the junction part, the whole shape may be other shapes, such as a square, not only circular like a figure example. The cross-sectional shapes of the annular gaskets 1A to 1E are not limited to a square shape as shown in the drawings, and other shapes such as a circular shape can be adopted. Further, the joining method of the joining portion 4 is not limited to the joining method shown in the figure as long as the elastic members arranged on the medium 2 to be sealed can be joined together.

1 (1A to 1E) annular gasket 10 medium to be sealed 2 medium side to be sealed 20 (sealing medium side) elastic material 3 anti-sealing medium side 30 (anti-sealing medium side) elastic material 4 joint

Claims (5)

An annular gasket that seals a medium to be sealed, which is formed by annularly molding two or more kinds of elastic materials having different characteristics in a radial direction,
Two or more types of uncrosslinked string-like elastic material having different characteristics are respectively placed in parallel in the radial direction in an annular mold and heated to be crosslinked and molded.
Both ends of the elastic material are provided with joint portions joined in a state where the elastic materials arranged on the sealing target medium side are integrated by the cross-linking molding. . The annular gasket according to claim 1,
An annular gasket characterized in that two or more kinds of elastic material materials arranged in the mold are combined in advance. In the annular gasket according to claim 1 or 2,
Consists of two kinds of elastic materials,
An annular gasket characterized in that the other elastic material is surrounded by the elastic material arranged on the medium side to be sealed. The annular gasket according to claim 3,
An annular gasket characterized in that the elastic material on the medium side to be sealed is made of fluoro rubber, and the other elastic material is made of silicone rubber.   Two or more types of uncrosslinked string-like elastic material materials having different characteristics are arranged in parallel in the radial direction in the mold, and the elastic material materials on the sealing target medium side are disposed at both ends of the elastic material material. A method for producing an annular gasket, characterized in that the annular gasket is integrally formed by heating and cross-linking molding in this state.

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