JP3208126B2 - Gasket made of porous fluorine resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing member for a joint portion of various pipes such as a sanitary pipe in a production plant for medicines, foods, drinking waters, etc. and an opening / closing portion of various containers for accommodating chemicals, solvents and the like. The present invention relates to a porous fluororesin gasket to be used.

[0002]

2. Description of the Related Art For example, as a gasket for sealing a joint portion (between ferrules) of a sanitary pipe, there is generally a rubber annular gasket made of silicon rubber or the like or an annular gasket made of PTFE (PTFE). However, those made of rubber tend to elute the plasticizer during long-term use, and are difficult to apply to sanitary piping that requires a high degree of cleanliness. In the case of sanitary piping,
The frequency of performing the steam sterilization process is high, but when such a process is performed, the gasket is used under high-temperature conditions, so that the gasket is easily deteriorated, and there is a problem in durability. In particular, in the case of cutting due to deterioration, leakage occurs and the predetermined sealing function cannot be exhibited. On the other hand, those made of PTFE do not suffer from the above-mentioned problems due to the characteristics of PTFE, but are inferior in flexibility, adaptability, restoring property, etc. because they are hard. Therefore, in order to exert a predetermined sealing function, an extremely large tightening torque is required, frequent retightening work is required, and it is difficult to recover the sealing function by retightening.

[0003] In recent years, as a solution to the problem of such a silicon rubber gasket or PTFE gasket, for example, as disclosed in Japanese Patent Application Laid-Open No. Hei 5-99343, porous PTFE, that is, a porous PTFE gasket, is used. A gasket made of porous fluororesin using PTFE as a constituent material has been proposed).

[0004] Since such a porous fluororesin gasket is made of porous PTFE, which is a soft material, the PTFE inherently has excellent durability, cleanliness, chemical resistance and the like. While having the characteristics described above, it has excellent flexibility, conformability, resilience, etc., which cannot be obtained with a normal PTFE gasket, and can be suitably used even under severe sealing conditions in sanitary piping. Things.

[0005]

However, such a gasket made of only porous PTFE (hereinafter referred to as "conventional gasket") is made of a material (porous PTF).
Due to the nature of E), it is easily deformed, so that it is extremely difficult to handle, and it is not easy to mount the sanitary pipe to the joint. For example, when attaching a conventional gasket between ferrules or pipe flanges of a sanitary pipe, the end of the gasket may be held by hand, but if the gasket end is not carefully held, the end may be There is a risk of local deformation. As described above, the conventional gasket is easily deformed by applying only a small force, so that it is necessary to handle the gasket with care. Further, the inner peripheral surface of the pipe and the inner peripheral surface of the gasket are not flush with each other, and a step is generated, which causes a liquid pool which is regarded as a problem in sanitary piping and the like. Therefore, it is a fact that the loading and unloading work of the gasket to the pipe joint or the like cannot be efficiently and quickly performed.

Further, the conventional gasket is formed by punching and pressure-forming a sheet-like material made porous of PTFE by stretching, and therefore cannot be formed into a complicated shape.
Therefore, the conventional gasket may not be able to be mounted depending on the shape of the gasket mounting surface, and its use is greatly limited.

[0007] Conventional gaskets are made of porous P.
Since the sealed fluid is a porous body made of TFE, regardless of whether the sealed fluid is a liquid or a gas, depending on the sealing conditions, the sealed fluid permeates from the gasket portion directly in contact with the sealed fluid. , So-called permeation leakage may occur. Also, once the sealed fluid permeates into the gasket, it cannot be removed. For example, in a chemical plant that manufactures multiple types of chemicals, it is necessary to replace the gasket every time a different chemical is manufactured. There is annoyance. In order to prevent such leakage, it is conceivable to increase the molding density of the gasket. However, there is a limit to increasing the molding density, and it is impossible to reliably prevent the leakage. Further, if the molding density is increased more than necessary, the original properties (flexibility, etc.) of porous PTFE will be impaired, and the significance of using porous PTFE as a constituent material will be lost. As described above, in the conventional gasket including only the porous PTFE, permeation and leakage of the sealed fluid into the gasket are fatal defects in terms of the material. In fact, their use is greatly restricted.

The present invention provides a gasket made of a porous fluororesin that can solve the above-mentioned problems without losing the characteristics and significance of using a porous fluororesin such as porous PTFE as a constituent material. It is intended to do so.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a ferrule.
In the gasket made of porous fluororesin that seals between (5a, 5b) , in order to achieve the above object, in particular, a porous gasket is used.
Gasket body (22) made of porous fluorine resin and fluorine
Non-porous fluororesin molding (23) molded with resin
It is to propose that you configure the Ranaru ones.
The non-porous fluororesin molded body is formed by solidifying a part of a gasket body made of a porous fluororesin (for example, a part directly in contact with a sealed fluid) by solidification or pressure solidification. Excludes quality.

In such a gasket made of porous fluororesin, the gasket body (22) has a flat annular plate.
The fluororesin molded body (23) has a shape
Cylindrical positioning that can be fitted to the outer periphery of the ferrule (5a)
Engagement portion (23a) and a ring protruding inward from one end edge thereof
L-shaped toroidal body consisting of an L-shaped connecting portion (23b)
And an annular recess formed in the inner periphery of the connecting portion (23b).
Fits the outer periphery of the gasket body (22) to the part (23c)
With the gasket body (22) concentric
And the inner periphery of the connecting portion (23b).
On both sides on the end side, the opposite side of the ferrule (5a, 5b)
An annular recess capable of engaging the formed annular recess (6a, 6b)
The ridges (23d, 23e) are integrally formed, and
(23b) Thickness of inner and outer peripheral end portions Ti, To and intermediate portion
The tightening pressure of the gasket body (22) is
When the upper limit of the positive range is reached,
At least one of the intermediate portions is a ferrule (5a, 5b)
Between the ferrules (5a, 5b)
It is set to block access.

[0011]

As the porous fluororesin constituting the gasket main body, an optimal one is selected according to the use conditions and the like. Usually, PTFE (polytetrafluoroethylene) or PFA (perfluoroalkoxyfluororesin) is used. (Porous PTFE or porous P)
FA) is used.

The fluororesin material constituting the fluororesin molding is selected according to the sealing conditions, application and manufacturing method of the gasket, but is generally superior in mechanical strength to the porous fluororesin material. Preferably, one is used.
Specifically, PCTFE (ethylene trifluoride chloride resin),
FEP (TFE-HFP copolymer ((ethylene tetrafluoride-
Hexafluoropropylene copolymer)), PFA (fluoroalkoxyethylene resin), ETFE, ECTFE, PVDF
(Vinylidene fluoride resin), VDF-HFP copolymer (vinylidene fluoride-propylene hexafluoride copolymer), VDF-
HFP-TFE copolymer (vinylidene fluoride-propylene hexafluoride-ethylene tetrafluoride copolymer), CTFE-VDF
It is possible to use a copolymer (ethylene trifluoride chloride-vinylidene fluoride copolymer), a TFE-PP copolymer (ethylene tetrafluoride-propylene copolymer), a vinylidene fluoride-based fluoro rubber, or the like. Preferred .

The gasket of the present invention is obtained by, for example, obtaining a gasket body made of a porous fluororesin by the same method as that known in the art, and disposing this gasket body in an injection mold having a predetermined shape. After melting and injecting a fluororesin material having a lower melting point than that of the constituent material (PTFE or PFA) in a gap formed with the gasket main body formed inside, the solidified resin is cooled and solidified to form a shape corresponding to the above gap. It can be obtained by integrally connecting the fluororesin molded body to the gasket main body. When the gasket is obtained by such a manufacturing method, the molding (injection molding) of the fluororesin molded body and the strong connection of the fluororesin molded body to the gasket main body, which is a porous fluororesin molded body, can be performed simultaneously. In order to perform this process, a fluorine resin material having a melting point lower than that of PTFE or PFA (for example, the melting point of PTFE is 330 ° C.) as a constituent material of the gasket body should be used as a material of the fluorine resin molded body. is necessary. Specifically, for example, when the gasket body is made of porous PTFE, the above-mentioned PCTFE, FEP, PF
A, ETFE, ECTFE, PVDF, VDF-HFP
Copolymer, VDF-HFP-TFE copolymer, CTFE
-VDF copolymer, TFE-PP copolymer or vinylidene fluoride-based fluoro rubber is used.

The gasket of the present invention can be manufactured by separately manufacturing a gasket main body and a fluororesin molded body, and then densely fitting a part of the gasket main body in a recess formed in the fluororesin molded body. It can also be obtained by fitting. In the case of such a manufacturing method, the constituent material of the gasket main body (P
There is no limitation that it is necessary to use a fluororesin material having a lower melting point than TFE or PFA), and a gasket according to the sealing conditions and application can be arbitrarily used. However, even in the case of such a manufacturing method, it is preferable to use a fluororesin material (for example, the one described above) which is superior in mechanical strength to the porous fluororesin material. In this manufacturing method, it is also possible to form a concave portion in the soft gasket main body and fit a part of the fluororesin molded body into the concave portion. It is also possible to integrate the separately manufactured gasket main body and the fluororesin molded body using an adhesive, but in such a case, contamination of the sealed fluid due to elution of the adhesive component does not occur. It is preferable to select a suitable adhesive.

[0016]

FIG. 1 is a block diagram showing an embodiment of the present invention.
Specifically described with reference to to 5.

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

The porous fluororesin gasket 21 according to the present invention in the embodiment of this is prevented with excessive tightening of the gasket body, the end face outer peripheral portion of and one of the ferrule 5b can improving the durability or the like The shape of the fluororesin molded body 23 is devised so that it can be attached to the sanitary pipes 4a and 4b provided with the annular projections 5c.

[0033] That is, the gasket 21, as shown in FIGS. 1 and 2, the gasket body 22 is a sealing function part, made of fluorine resin molded body 23 is a non-sealing function portion that is not directly involved in the sealing function. Incidentally, Sani Tali pipe 4a to which the gasket 21 is fitted, the joint structure 4b (ferrule 5a, 5b of the shape and the clamping means (clamping band 7), etc.) is as shown in FIG. 5, off
The sanitary pipes 4a,
The annular recesses 6a and 6b concentric with 4b are formed.
You. On the outer peripheral portion of the end face of one ferrule 5b,
As described above, the annular projection 5c is provided. Also clamp
The band 7 is composed of two or three arc-shaped segments connected in a ring.
7a ...
And tighten the connecting screw between the segments 7a
By reducing the shape of the ferrules 5a and 5
b can be tightened.

The gasket body 22, FIGS. 1, 2 and
3 As shown in (A), porous PTFE or porous PFA
In the shape of a flat annular plate. The thickness T of the gasket body 22 is uniformly set, an inner diameter, Sa Bryde pipes 4a, 4b of the ferrule 5a,
5b, the pipe 4
They are set so as to match the inner diameters of a and 4b.

As shown in FIGS. 1 and 2 , the fluororesin molded body 23 has an L-shaped cross section composed of a cylindrical positioning engaging portion 23a and an annular connecting portion 23b protruding inward from one end edge thereof. It is an annular body, and is integrally connected to the gasket main body 22 concentrically with the outer peripheral portion of the gasket main body 22 fitted in an annular concave portion 23c formed in the inner peripheral portion of the connecting portion 23b. is there. In addition, the annular concave portions 6a, 5b of the ferrules 5a, 5b are provided on both surfaces on the inner peripheral end side of the connecting portion 23b.
Annular protrusions 23d and 23e that can be engaged with 6b are integrally formed. An annular step 23f that can engage with the annular projection 5c of the ferrule 5b is provided on the outer peripheral end of the connecting portion 23b.
Are formed. The inner diameter of the positioning engaging portion 23a is being matched to the outer diameter of the gasket main body 22 so as be fitted to the outer periphery of the ferrule 5a. The thicknesses Ti, To, and Tc of the inner peripheral end portion where the protruding ridges 23d and 23e are formed, the outer peripheral end portion where the annular step portion 23f is formed, and the intermediate portion thereof are determined by making the gasket 21 correspond to the ferrules 5a and 5b. In the case where the gasket main body 22 is sandwiched between the gasket main body 22 and the gasket main body 22 so that the gasket main body 22 is not excessively tightened beyond the appropriate pressure range.
(Elastic force, restoring force) and thickness T. That is, when the tightening pressure of the gasket main body 22 reaches the upper limit value (maximum tightening pressure) of the appropriate range, at least one of the inner and outer peripheral end portions and the intermediate portion is made of the ferrules 5a and 5b. To prevent further approach of the ferrules 5a and 5b. Of course, Ti and To are gasket body 22
In the state where the tightening pressure is the lower limit of the appropriate range (minimum tightening pressure), the ridges 23d and 23e
a, 6b or the annular step 23f is not detached from the annular projection 5c.

[0036] Such a configuration such vinegar gasket 21, as shown in FIG. 3
It can be manufactured by the procedure shown in FIG. First, the known
In the same manner as for a porous PTFE gasket,
The gasket main body 22 having the above-mentioned shape is obtained from the G-shaped material (FIG.
3 (A)). In addition, as the sheet material, for example, P
Crystal orientation treatment of TFE or PFA material by pressure roll
After that, using a rubber-coated pinch roll,
(For example, when PTFE material is used, 327
At a stretching ratio of 110 to 300%.
A porosity of 40 to 86% is used. And
This gasket main body 22 is formed into an injection mold 2a having a predetermined shape.
2b. That is, the injection mold 2a, into the inside 2b, and the cavity 2c having a shape matching the gasket 21 is formed by placing the gasket body 22 in the cavity 2c, outside the cavity surface and the gasket main body 22 to form voids 2d shape that matches the fluorine resin molded body 23 between the surface (FIG. 3 (B)). Furthermore, this gap 2d, melting fluorine resin material 3, after injection, cools the fluorine resin molded body 23 is injected into the void 2d, solidify (Fig. 3 (C)). The fluororesin material 3 has a lower melting point than PTFE or PFA and is harder (mechanical strength) than porous PTFE or PFA.
PCTFE or the like is selected in accordance with the sealing conditions, the function of the fluororesin molded body 23, and the like. example
If the gasket body 22 is made of porous PTFE,
In this case, the sealing conditions and the fluorine resin
PCTFE, FEP, P
FA, ETFE, ECTFE, PVDF, VDF-HF
P copolymer, VDF-HFP-TFE copolymer, CTF
E-VDF copolymer, TFE-PP copolymer or fluorine fluoride
Nilidene-based fluorine rubber or the like is used.

At the time of such injection molding, a fluorine resin material
3 has a lower melting point than the constituent material of the gasket body 22
In order to use this, the molten fluororesin material 3 is
The gasket body 22 is also made of fluororesin
No damage is caused by the heat of 3. But gas
A portion of the body 22 facing the space 2d, ie, a fluorine resin
In the porous portion directly touching the material 3, the porous portion
Depends on the molding pressure and temperature change due to the injection of the fluororesin material 3.
Deformed and firmly bonded to the solidified fluororesin
Will be. That is, the pores of the porous portion
The material 3 penetrates and solidifies, so-called anchor effect
Is exerted, and the gasket body 22 and the fluorine resin solidified material
The contact portion with the fluororesin molded body 23 is meshed in an uneven shape.
It will be firmly connected in the state. Therefore, above
According to the method, the gasket main body 22 and the fluororesin molding
Solid connection with the body 23 without using adhesive
The obtained gasket 21 can be obtained. Further, gas <br/> gasket 21, since a portion of the gasket main body 22 is of the form that fits into the recess 23c formed in the fluorine resin molded body 23, and forming the fluorine resin molded body 23 It can also be manufactured by separately connecting the gasket body 22. That is, as shown in FIG. 4 , the fluororesin molded body 23 is manufactured independently by injection molding or the like, and the gasket main body 2 is inserted into the recess 23c of the fluororesin molded body 23.
The outer periphery of the second member is closely fitted. The fitting of the gasket main body 22 into the concave portion 23c is performed by the gasket main body 2.
At the time of the heat treatment 2, the outer peripheral portion is pressed into the concave portion 23c with an appropriate roll. By doing so, the fitting connection between the two bodies 22 and 23 can be strengthened without using an adhesive. According to this manufacturing method, the gasket 21 formed by integrally connecting the gasket main body 22 made of a different material and the fluororesin molded body 23 can be easily manufactured. Moreover, as in the case of the manufacturing method shown in FIG. 3 , the two bodies 22, 23 can be firmly connected together without using any adhesive or the like.
The gasket 21 having a high degree of cleanness can be easily manufactured. Further, unlike the case of the manufacturing method shown in FIG. 3, there is no limitation that a fluororesin having a lower melting point than that of the material of the gasket main body 22 is used as a constituent material of the fluororesin molded body 23, and sealing conditions and the like are taken into consideration. Can be arbitrarily selected. For example, the fluororesin molded body 23 may be made of the same material (PTFE or PFA) as the gasket body 22.

[0038] In Thus, gasket 21, as shown in FIG. 5, sanitary pipes 4a, ferrule 5a formed at an end portion of 4b, by previously is interposed in a proper clamping pressure state between 5b, sanitary piping 4a, but the joint portion of the 4b is intended to seal, mounted in the gasket 21 to such joint portion, holding the gasket 21 ferrule 5a, in a predetermined position that is the pipe 4a, the 4b concentric position between 5b In this state, the ferrules 5a and 5b are tightened by the clamp band 7.

[0039] At this time, the projection 23d of the gasket 21,
23e is engaged with the annular concave portions 6a and 6b,
Proper position of ferrules 5a, 5b (sanitary pipes 4a,
4b) can be accurately positioned. The positioning by the ridges 23d and 23e is performed because the ridges 23d and 23e are hard portions forming a part of the fluorinated resin molded body 23.
Can be accurately and easily performed in combination with the fact that it has a cylindrical positioning engagement portion 23a having a size that can be fitted to one ferrule 5a. By the way, on
The positioning by the ridge described above is
This is being done, but with conventional gaskets,
Until the ferrule is tightened by the clamp band.
The gasket should be kept in the proper position
Difficult, anyway, clamping work by clamp band
There is a risk that the ridge will be displaced from the annular recess during operation. like this
If the ferrule is tightened with misalignment,
Ridge is pinched between flat surfaces where there is no
The tightening surface pressure of the entire gasket becomes uneven.
Therefore, a good sealing function is not exhibited. Also, temporarily,
Even if the sealing function is achieved, the inner circumferential surface of
A step is generated between the inner peripheral surface of the socket and a liquid pool is generated,
It becomes impossible to maintain the purity of the sealed fluid. But,
The gasket 21 is provided on the outer peripheral portion of the gasket main body 22.
A cylindrical member having a size that can be fitted to one ferrule 5a
Since it has the positioning engagement portion 23a,
The positioning engagement portion 23a is engaged with the outer peripheral portion of the ferrule 5a.
The protrusions 23d and 23e are not
a, 6b
Can be. Therefore, the state ferrule 5a by the clamp band 7, which 5b tighten the gasket 21 of the ferrule 5a, can be carried out in a state of being securely held in proper position between 5b, the gasket body 22 is tightened evenly and properly Can be mounted very easily. In addition, since a part of the hard fluororesin molded body 23 (excluding the positioning engagement part 23a) is sandwiched between the ferrules 5a and 5b together with the gasket body 22, the thicknesses Ti, To and Tc are set as described above. With such a setting, there is no possibility that the gasket main body 22 is excessively tightened, and an appropriate tightening operation can be easily performed without requiring special skills. Further, a portion for positioning the gasket 21 (the ridges 23d, 2d).
3e) are all constituted by a part of the hard fluororesin molded body 23, so that the fluororesin molded body 2
In combination with the fact that a part of the gasket 3 takes on the clamping force of the ferrules 5a and 5b, even when the gasket 21 is repeatedly attached and detached or retightened, the gasket 21 can sufficiently withstand this, greatly reducing the number of times of use. Can be increased .

The gasket 21 is made of a porous fluorine resin.
The gasket body 2 is attached to the outer periphery of the gasket body 22 made of
Fluororesin moldings that are rigid and high-strength annular bodies as compared to 2.
23 are integrally connected to each other.
Gasket main body 22 is reinforced by the presence of resin molded body 23
The strength and durability of the gasket as a whole
Conventional gasket composed only of silicone resin (porous PTFE)
This is a significant improvement over the cost. Therefore,
When setting between ferrules 5a and 5b
And unless you treat the gasket 21 very roughly,
Is not deformed or damaged. Because of this,
The engagement of the positioning engagement portion 23a with the ferrule 5a causes
Quickly and easily perform the proper positioning of the skewers 21.
Combined with the sanitary piping 4a,
Efficient and easy installation of gasket to 4b joint
And the gasket 21 can be
Can be mounted accurately.

Also, the ferrules 5a and 5b were tightened.
In this case, the gasket main body 22 made of porous fluororesin is used.
Is pinched, but is located outside the ferrules 5a and 5b.
The positioning engagement portion 23a is not pressed. Thus, the gas
Having a fluorine resin molded body 23 harder than the
Despite the presence of the gas,
This is a part that does not participate in the sealing function of the
The function is exclusively provided by the gasket body 22 made of porous fluororesin.
Flexibility, familiarity, and resilience
Such as porous fluororesin gasket
Good sealing function.
You. Further, the fluororesin molded body 23 is made of a fluorine resin having excellent chemical resistance and the like.
It is composed of a molded article of fluororesin
The connection between the molded body 23 and the gasket main body 22 is made by injection molding.
This is performed by physically connecting the unevenness due to the anchor effect, and the adhesive
Are not used, the fluororesin molded body 23
No problem such as elution of impurities from the adhesive
No.

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

As is clear from the above description, in the gasket made of the porous fluororesin of the present invention, a part or a plurality of the gaskets are formed of a nonporous fluororesin molded body. Accordingly, the fluororesin molded body can function as a reinforcing material, and the handleability and durability of the gasket can be greatly improved. In addition, since the fluororesin molded body has almost no shape limitation such as a gasket main body made of porous fluororesin, various shapes and the like of the fluororesin molded body can be variously adjusted. It can be mounted on piping joints and the like that have a shape and structure, and can be used for a wide range of applications. Further, since the portion made of the fluororesin molding is non-porous, the portion that may cause permeation leakage (the portion that directly contacts the sealed fluid, etc.) is made of the non-porous fluororesin molding. By doing so, it is possible to reliably prevent permeation leakage, which is a fatal defect in a porous fluororesin gasket.

[Brief description of the drawings]

FIG. 1 is a front view showing a gasket according to the present invention .

FIG. 2 is a vertical sectional side view taken along the line VI-VI of FIG.

3 is a vertical sectional side view showing a manufacturing step of the gasket.

FIG. 4 is a view showing a method of manufacturing the gas shown in FIG .
Longitudinal side showing a part of the manufacturing process when obtaining a socket
FIG.

[Fig. 5] The gasket is attached to the joint of the sanitary pipe.
It is a vertical side view which shows the state which was set.

[Description of Signs ] 2a, 2b: Injection mold, 2c: Cavity, 2d: Empty
Gap, 3 ... fluororesin material, 4a, 4b ... sanitary pipe, 5
a, 5b: ferrule, 6a, 6b: annular recess, 7: h
Lamp band, 21 ... Gasket, 22 ... Gasket book
Body, 23: fluororesin molded body, 23a: positioning engagement portion,
23c: concave portion, 23b: connecting portion, 23d, 23e: protrusion
Article.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-121599 (JP, A) JP-A-10-281291 (JP, A) JP-A 8-233109 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) F16J 15/06-15/12 B32B 5/18 B32B 27/30 C09K 3/10

Claims (3)

(57) [Claims] 1. A seal is provided between ferrules (5a, 5b).
A gasket body made of porous fluororesin, a gasket body (22) made of porous fluororesin, and a nonporous fluororesin molded article (23) made of fluororesin.
The gasket body (22) has a flat annular plate shape.
And the fluororesin molded body (23) is made of one ferrule (5a).
Cylindrical positioning engagement portion (23a) that can be fitted to the outer peripheral portion of the cylinder
And an annular connecting portion (23) protruding inward from one end edge thereof.
b) an annular body having an L-shaped cross section,
In the annular concave portion (23c) formed in the inner peripheral portion of (23b)
With the outer periphery of the gasket body (22) fitted,
Concentric with the gasket body (22) and integrally connected
Are as hereinbefore, on both sides of the inner peripheral end side of the connecting portion (23b), the ferrule
An annular recess (6a, 5b) formed on the facing surface of (5a, 5b).
6b) can be engaged with one of the annular ridges (23d, 23e).
And the thicknesses Ti, To and To of the inner and outer peripheral end portions of the connecting portion (23b).
The thickness Tc of the intermediate portion is determined by tightening the gasket body (22).
When the pressure reaches the upper limit of the appropriate range,
And at least one of the intermediate portions is a ferrule (5a,
5b), the ferrule (5a, 5b)
A gasket made of a porous fluororesin, which is set so as to prevent the above approach . 2. The gasket made of a porous fluororesin according to claim 1 , wherein the porous fluororesin is porous PTFE or porous PFA. 3. A non-porous fluororesin molded article comprising:
At least PCTFE, FEP, PFA, ETFE, E
CTFE, PVDF, VDF-HFP copolymer, VDF
-HFP-TFE copolymer, CTFE-VDF copolymers, wherein the TFE-PP copolymer and a fluorine resin selected from vinylidene fluoride fluorine rubber is used, according to claim 1 or claim Item 4. A gasket made of a porous fluororesin according to Item 2 .