JP2000257718A - Porous fluororesin gasket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a porous fluororesin gasket superior in handling characteristic and durability. SOLUTION: A gasket 11 comprises a gasket main body 12 made of a porous fluororesin and a non-porous fluororesin molding 13 connected thereto. A porous PTFE or a porous PFA is used as a constituent material for the gasket main body 12. The fluororesin molding 13 is obtained by injection molding and PCTFE, FEP, PFA, ETFE, ECTFE, PVDF, VDF-HFP copolymer, VDF- HFP-TFE copolymer, CTFE-VDF copolymer, TFE-PP copolymer, or vinylidene fluoride rubber or the like is used as a constituent material thereof.

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 the ferrules of a sanitary pipe or between pipe flanges, the end of the gasket may be held by hand, but if the gasket end is not carefully held,
The end may be locally deformed. in this way,
Conventional gaskets are easily deformed by the application of only a small force, and therefore must be handled 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 provides a gasket made of a porous fluororesin, in order to achieve the above object.
In particular, it is proposed that a part or a plurality of parts be formed of a nonporous fluororesin molded body. In the nonporous fluororesin molded body referred to herein, a portion (for example, a portion directly in contact with a sealed fluid) of a portion (hereinafter, referred to as a "gasket body") formed of a porous fluororesin is melt-solidified or added. It does not include those made non-porous by compaction.

In such a gasket made of a porous fluororesin, if it is necessary to reliably prevent permeation leakage due to the sealing conditions and application, a part or a part thereof involved in the sealing function is removed. It is preferable to use an ineffective fluorine resin molded body. In particular, it is preferable that the portion directly in contact with the sealed fluid is formed of a fluororesin molded body. For example, when the gasket has an annular plate shape, it is preferable that at least one of the inner peripheral portion and the outer peripheral portion is formed of a fluororesin molded body.

Further, in addition to the above-mentioned part or a part related to the sealing function being constituted by a fluororesin molding, or the part relating to the sealing function not being constituted by a fluororesin molding, The handling of the gasket can be improved by forming a part or a part of the part that does not participate in the sealing function with a fluororesin molded body.

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. preferable. When a plurality of parts are formed of a fluororesin molded body, all the fluororesin molded bodies are made of the same fluororesin material in accordance with the functions required for the parts formed of the fluororesin molded bodies. Even if it comprises, each fluororesin molded object or several fluororesin molded objects may be comprised with a fluororesin material different from another fluororesin molded object.

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.
19 will be specifically described.

FIGS. 1 to 4 show a first embodiment. A gasket made of a porous fluororesin (hereinafter referred to as "first gasket 11") according to the present invention in this embodiment is a sanitary. It is used as a gasket for piping and is made of porous fluororesin (porous PTFE or porous PF).
The gasket main body 12 constituted by A) and the non-porous fluororesin molded body 13 constituting a portion of the first gasket 11 which does not participate in the sealing function.

As shown in FIGS. 1, 2 and 3A, the gasket main body 12 has concentric annular ridges 12a, 1
2b is formed into an annular plate shape in which an annular groove 12c is formed on the outer peripheral surface while bulging the gasket 1b.
1 is a part that exhibits a sealing function. The inner diameter of the gasket body 12 matches the inner diameter of the sanitary pipes 4a, 4b when the first gasket 11 is properly mounted on the joints of the sanitary pipes 4a, 4b described later, and the outer diameter of the gasket body 12 is a ferrule described later. It is set so as to substantially match the outer diameter of 5a, 5b.

As shown in FIGS. 1 and 2, the fluororesin molded body 13 has an L-shaped cross section comprising a cylindrical positioning engaging portion 13a and an annular connecting portion 13b projecting inward from one end edge thereof. An annular body, which is concentric with the gasket main body 12, and the connecting portion 13b is formed in the annular groove 12 of the gasket main body 12.
In a state fitted to c, it is integrally connected to the outer peripheral portion of the gasket main body 12. The inner diameter of the positioning engagement portion 13a matches the outer diameter of the gasket main body 12, and can be fitted to the outer peripheral portion of one ferrule 5a. Further, the positioning engagement portion 13a is provided in the gasket main body 1.
2, perpendicular to the surface on which the ridge 12a is formed,
The amount of protrusion H from the surface is adjusted by fitting the ferrule 5a to the outer peripheral portion of the ferrule 5a.
1 is set to such an extent that 1 can be held. In this example, the protrusion amount (projection amount) h of the ridge 12a is set to be slightly larger.

The first gasket 11 having such a configuration is
For example, it can be manufactured as follows.

First, the gasket main body 12 is obtained by the same method as a known porous PTFE gasket. That is, a gasket main body 12 having the above-mentioned shape is obtained by press-molding an annular base material from a sheet material made of porous PTFE or porous PFA using a mold (FIG. 3A). As the sheet material, for example, after a PTFE material or a PFA material is subjected to crystal orientation treatment by a pressure roll, a rubber-coated pinch roll is used to apply a suitable temperature condition (for example, less than 327 ° C. when a PTFE material is used). )), A material having a porosity of 40 to 86% obtained by stretching at a stretching ratio of 110 to 300% is used.

Next, the gasket body 1 thus obtained
2 are arranged in injection molds 1a and 1b having a predetermined shape. That is, the first gasket 1 is provided in the injection molds 1a and 1b.
1 is formed, and a cavity 1c having a shape corresponding to 1 is formed.
By arranging the gasket main body 12 in the cavity 1c, a gap 1d (including the annular groove 12c of the gasket main body 12) between the cavity surface and the outer surface of the gasket main body 12 has a shape conforming to the fluororesin molded body 13. Is formed (FIG. 3B). Then, the fluorine resin material 3 is formed in the gap 1d by an injection ram or the like in the same manner as in normal injection molding.
Is melted and injected, and the fluororesin material 3 injected into the gap 1d is cooled and solidified (FIG. 3C). Such a void 1
By solidifying the fluororesin material 3 in d, the fluororesin molded body 13 integrally connected to the gasket main body 12 is formed, and the first gasket 11 described above is obtained. The fluororesin material 3 has a lower melting point than PTFE or PFA which is a constituent material of the gasket main body 12 and is harder than porous fluororesin material (porous PTFE material or porous PFA material), that is, excellent in mechanical strength. Is used. For example, when the gasket body 12 is made of porous PTFE, the fluororesin material 3 may be PCTFE, FEP, PEP, depending on the sealing conditions, the function of the fluororesin molded body 13, and the like.
FA, ETFE, ECTFE, PVDF, VDF-HF
P copolymer, VDF-HFP-TFE copolymer, CTF
E-VDF copolymer, TFE-PP copolymer, vinylidene fluoride-based fluororubber and the like are used.

At the time of such injection molding, since a material having a melting point lower than that of the constituent material of the gasket body 12 is used as the fluorine resin material 3, the molten fluorine resin material 3 is filled with the void 1d.
The gasket main body 12 is not damaged by the heat of the fluororesin material 3 even when the injection is performed. However, in the portion of the gasket main body 12 facing the gap 1d, that is, the porous portion directly touching the fluororesin material 3, the porous portion is deformed by the molding pressure or temperature change due to the injection of the fluororesin material 3, and the fluororesin material is deformed. This will result in a strong physical bond with the solidified material. That is, the fluororesin material 3 penetrates into the pores of the porous portion and solidifies, so-called anchoring effect is exerted, and the gasket body 12 and the contact portion (gasket) between the fluororesin molded body 13 which is the fluororesin solidified material Body 12
(The portion where the annular groove 12c is fitted to the connecting portion 13b of the fluororesin molded body 13 and the contact portion between the outer peripheral surface of the gasket main body 12 and the inner peripheral surface of the positioning engagement portion 13a of the fluororesin molded body 13) are uneven. It will be firmly connected in the state of meshing with. Therefore, according to the above-described method, it is possible to obtain the first gasket 11 in which the gasket main body 12 and the fluororesin molded body 13 are firmly connected without using an adhesive or the like.

As shown in FIG. 4, the first gasket 11 is interposed between the ferrules 5a and 5b formed at the ends of the sanitary pipes 4a and 4b in a proper clamping state, so that the first gasket 11 can be sanitized. This seals the joints of the pipes 4a and 4b.

The mounting of the first gasket 11 to the joint portion is performed by holding the first gasket 11 at a predetermined position between the ferrules 5a and 5b, that is, at a position concentric with the pipes 4a and 4b. Is clamped by a clamp band 7. In general, the clamp band 7 has a two- or three-segment structure composed of two or three arc-shaped segments 7a... Connected in a ring shape, and tightens a connection screw between the segments 7a, 7a to form a ring shape. Is reduced in diameter, so that the ferrules 5a and 5b can be tightened.

The ferrules 5a, 5b are provided with annular recesses 6 concentric with the sanitary pipes 4a, 4b.
a, 6b are formed. Therefore, the protrusions 12a, 12b of the first gasket 11 are engaged with the annular recesses 6a, 6b, so that the ferrules 5a, 5b can be accurately positioned at appropriate positions (positions concentric with the sanitary pipes 4a, 4b). It can be carried out. Such ridges 12a, 1
Positioning by the conventional gasket is also performed in the conventional gasket. However, in the conventional gasket, it is difficult to hold the gasket at the above-described proper position until the ferrule is tightened by the clamp band. There is a possibility that the ridge may be displaced from the annular concave portion during the tightening operation by the band. If the ferrule is tightened in a state where such a deviation has occurred, the ridge portion will be pinched between the flat surfaces where there is no annular concave portion, and the tightening surface pressure of the entire gasket becomes non-uniform,
Good sealing function is not exhibited. Further, even if the sealing function is exerted, a step is generated between the inner peripheral surface of the pipe and the inner peripheral surface of the gasket to generate a liquid pool, and it becomes impossible to maintain the purity of the sealed fluid.

However, the first gasket 11 has a cylindrical positioning engagement portion 13a on the outer peripheral portion of the gasket main body 12, which is large enough to fit into one ferrule 5a. By engaging the portion 13a with the outer peripheral portion of the ferrule 5a, the ridge 12
a and 12b can be reliably held at appropriate positions where they are engaged with the annular concave portions 6a and 6b. Therefore, the ferrules 5a and 5b can be tightened by the clamp band 7 while the first gasket 11 is securely held at an appropriate position between the ferrules 5a and 5b. Therefore, the first gasket 11 can be mounted in a state where the gasket main body 12 is uniformly and properly tightened, and the operation can be performed extremely easily.

The first gasket 11 is formed by integrally forming a fluororesin molded body 13 which is a rigid and high-strength annular body as compared with the gasket main body 12 on the outer peripheral portion of a gasket main body 12 made of porous fluororesin. The gasket main body 1 is reinforced by the presence of the fluororesin molding 13 because it is connected, and the strength and durability of the entire gasket are made of a conventional gasket made of only porous fluororesin (porous PTFE). It is greatly improved as compared with. Therefore, during the setting work between the ferrules 5a and 5b, etc., unless the gasket 11 is
It does not deform or break. For this reason, the positioning of the first gasket 11 can be performed quickly and easily by the engagement of the positioning engagement portion 23a with the ferrule 5a, so that the sanitary pipes 4a and 4b can be connected to the joints. The gasket mounting operation can be performed efficiently and easily, and the gasket 11
Can be accurately attached to a predetermined position.

When the ferrules 5a and 5b are tightened, the gasket main body 12 made of porous fluororesin is used.
Is pressed, but the positioning engagement portion 12a located outside the ferrules 5a and 5b is not pressed. Also, the connecting portion 23
b is located between the ferrules 5a and 5b, and is thinner than the gasket main body 1;
Does not affect the pinch pressure. As described above, although the first gasket 11 has the fluororesin molded body 23 that is harder than the gasket main body 12a, the fluororesin molded body 23 is a portion that is not involved in the sealing function of the gasket 11. Since the sealing function is provided solely by the gasket body 12 made of porous fluororesin, flexibility and
A good sealing function can be exhibited without impairing the original characteristics of the porous fluororesin gasket such as adaptability and restoring property. Further, the fluororesin molded body 23 is made of a fluororesin molded body having excellent chemical resistance and the like, and the connection between the fluororesin molded body 23 and the gasket main body 12 is caused by physical irregularities due to the anchoring effect of injection molding. Since the connection is performed and an adhesive or the like is not used, there is no problem that impurities are eluted from the fluororesin molded body 23 or the adhesive or the like.

Incidentally, the present invention is not limited to the above-described first embodiment, and can be appropriately improved and changed without departing from the basic principle of the present invention.

The gasket body made of a porous fluororesin (porous PTFE or porous PFA) is obtained by punching a sheet material as described above and press-molding the same.
Due to such a manufacturing method, it is inevitable to use a relatively simple shape. However, for a fluororesin molded body obtained by injection molding or the like, the shape or the like can be arbitrarily designed, and a complicated shape can be obtained. It is also possible. Therefore, according to the present invention, by devising the shape of the fluororesin molded body, the connection position to the gasket main body, and the like, FIG.
As shown in FIGS. 19 to 19, gaskets of various shapes and functions can be easily provided according to the sealing conditions and the structure (shape and structure of the ferrule, piping flange, etc.) of the gasket mounting device.

FIGS. 5 to 9 show a second embodiment. A gasket made of a porous fluororesin (hereinafter referred to as "second gasket 21") according to the present invention in this embodiment is a gasket. A sanitary pipe 4a, which can prevent excessive tightening of the main body, improve durability and the like, and has an annular projection 5c provided on an outer peripheral portion of an end face of one ferrule 5b.
The shape of the fluororesin molded body 23 has been devised so that it can be mounted on 4b.

That is, as shown in FIGS. 5 and 6, the second gasket 21 comprises a gasket main body 22 which is a sealing function part, and a fluororesin molded body 23 which is a non-seal function part which is not directly involved in the sealing function. . The joint structure (shape of ferrules 5a, 5b and fastening means (clamp band 7), etc.) of the sanitary pipes 4a, 4b to which the gasket 21 is attached is the same as that of FIG. Are the same as those shown in FIG.

The gasket main body 22 is made of porous PTFE or porous PFA as shown in FIGS.
In the shape of a flat annular plate. The thickness T of the gasket main body 22 is set to be uniform, and the inner diameter of the gasket main body 22 is the same as that of the first gasket 11, when the pipe 4a is clamped at an appropriate pressure between the ferrules 5a, 5b of the sanitary pipes 4a, 4b. , 4b.

As shown in FIGS. 5 and 6, 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 projecting inward from one end edge thereof. It is an annular body, and is integrally connected to the gasket 22 concentrically with the gasket 22 in a state where the outer peripheral portion of the gasket main body 22 is fitted in the annular concave portion 23c formed in the inner peripheral portion of the connecting portion 23b. . Also, the annular concave portions 6a, 6b of the ferrules 5a, 5b are provided on both surfaces on the inner peripheral end side of the connecting portion 23b.
Are formed integrally with each other. An annular step 23f that can engage with the annular projection 5c of the ferrule 5b is formed at the outer peripheral end of the connecting portion 23b. The inner diameter of the positioning engagement portion 23a is:
As with the first gasket 11, the outer diameter of the gasket main body 22 matches the outer diameter of the gasket main body 22, and can be fitted to the outer peripheral portion of the ferrule 5a. In addition, the ridges 23d, 2
The thickness T of the inner peripheral end portion where 3e is formed, the outer peripheral end portion where the annular step portion 23f is formed, and the intermediate portion thereof
i, To, and Tc attach the gasket 21 to the ferrule 5
In order to prevent the gasket main body 22 from being excessively tightened beyond the range of the appropriate pressure when the gasket main body 22 is sandwiched between a and 5b, the gasket main body 22 has a property (elastic force, restoring force) and a thickness T depending on the thickness T. Is set. That is,
When the tightening pressure of the gasket main body 22 reaches the upper limit of the appropriate range (maximum tightening pressure), at least one of the inner and outer peripheral end portions and the intermediate portion is sandwiched between the ferrules 5a and 5b. The ferrules 5a and 5b are set so as to be pressed to prevent the ferrules 5a and 5b from approaching further. Of course,
Ti and To can be obtained even when the tightening pressure of the gasket main body 22 is at the lower limit of the appropriate range (minimum tightening pressure).
The protrusions 23d and 23e are set so as not to come off from the annular concave portions 6a and 6b, or the annular step 23f does not come off from the annular protrusion 5c.

The second gasket 21 having such a configuration is
It can be manufactured by the same method as the first gasket 11. First, the gasket main body 22 having the above shape is obtained by the same method as that of the gasket main body 12 (FIG. 7A). Then, the gasket main body 22 is inserted into the injection mold 2 having a predetermined shape.
a, 2b. That is, the injection molds 2a, 2b
A cavity 2c having a shape conforming to the second gasket 21 is formed therein. By disposing the gasket main body 22 in the cavity 2c, a fluorine resin is formed between the cavity surface and the outer surface of the gasket main body 22. A gap 2d having a shape matching the molded body 23 is formed (FIG. 7).
(B)). Further, after the fluorine resin material 3 is melted and injected into the space 2d, the fluorine resin molded body 23 injected into the space 2d is cooled and solidified (FIG. 7C). The fluororesin material 3 is made of PTFE or P
A material having a melting point lower than that of FA and having a higher hardness (mechanical strength) than porous PTFE or porous PFA is used, and PCTFE or the like is selected according to sealing conditions, the function of the fluororesin molded body 23, and the like.

The second gasket 21 has a recess 2 in which a part of the gasket main body 22 is formed in the fluororesin molded body 23.
3c, it can also be manufactured by separately forming the fluorine resin molded body 23 and connecting the gasket main body 22. That is, as shown in FIG. 8, the fluororesin molded body 23 is manufactured independently by injection molding or the like, and the outer peripheral portion of the gasket main body 22 is closely fitted into the concave portion 23c of the fluororesin molded body 23. The gasket main body 22 is fitted into the concave portion 23c by pressing the outer peripheral portion of the gasket main body 22 into the concave portion 23c with an appropriate roll during the heat treatment. 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.
The gasket 21 having a high degree of cleanliness can be easily manufactured because the gasket 23 can be strongly and integrally connected without using any adhesive or the like. Also,
Unlike the case of the manufacturing method shown in FIG. 7, there is no limitation that a fluororesin having a melting point lower than that of the material of the gasket main body 22 is used as a constituent material of the fluororesin molded body 23, and it is optional in consideration of sealing conditions and the like. Can be selected. For example, the fluororesin molded body 23 may be made of the same material (PTFE or PFA) as the gasket body 22.

As shown in FIG. 9, the second gasket 21 is interposed between the ferrules 5a and 5b formed at the ends of the sanitary pipes 4a and 4b in an appropriate clamping state, so that the sanitary The second gasket 21 is mounted on the joints of the pipes 4a and 4b by sealing the gasket 21 with the ferrules 5.
This is performed by tightening the ferrules 5a and 5b with the clamp band 7 while holding the ferrules 5a and 5b at a predetermined position between the a and 5b, that is, at a position concentric with the pipes 4a and 4b.

At this time, the ridge 23 of the second gasket 21
d, 23e are engaged with the annular recesses 6a, 6b, so that the ferrules 5a, 5b can be properly positioned (the sanitary pipe 4).
(a position concentric with a, 4b) can be accurately performed. The positioning by the ridges 23d and 23e is performed because the ridges 23d and 23e are hard portions forming a part of the fluororesin molded body 23, and therefore, the fluororesin molded body 2 is used.
This can be performed accurately and easily, in combination with the fact that 3 has a cylindrical positioning engagement portion 23a having a size that can be fitted to one ferrule 5a. Therefore, the ferrules 5a and 5b can be tightened by the clamp band 7 while the second gasket 21 is securely held at an appropriate position between the ferrules 5a and 5b.
The gasket main body 22 can be mounted extremely easily in a uniformly and properly tightened state. In addition, a part of the hard fluororesin molded body 23 (a part except the positioning engagement part 23a) is formed together with the gasket body 22 by the ferrule 5
a, 5b, the thickness Ti, T
By setting o and Tc as described above, there is no possibility that the gasket main body 22 is excessively tightened, and proper tightening work can be easily performed without requiring special skills. Further, since the portions (projections 23d, 23e, etc.) for positioning the gasket 21 are all constituted by a part of the hard fluororesin molded body 23, as described above, one part of the fluororesin molded body 23 is formed. In addition to the fact that the part bears 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, and the number of uses can be greatly increased. Can be. Of course, the above-described operation and effect achieved in the first gasket 11 can be similarly achieved in the second gasket 21.

FIG. 10 shows a third embodiment, in which a gasket made of a porous fluororesin (hereinafter referred to as "third gasket 31") according to the present invention is a ferrule 5a. , 5b, the shape of the fluororesin molded body and the positions of the ridges have been devised so that they can be mounted on the sanitary pipes 4a, 4b provided with the annular projections 5c, 5d and the annular recesses 6a, 6b on the outer periphery of the opposing surfaces of the. Things.

That is, in the third gasket 31, FIG.
As shown in FIG. 0, the connecting portion 33b of the fluororesin molded body 33 has a stepped shape in which the annular projections 5c and 5d can engage, and the ridge 32
a and 32b are formed on the outer peripheral portion of the gasket main body 32. In addition, the fluororesin molded body 33 is used for the first gasket 11.
As described in the above, the gasket is not connected in a state of being deeply immersed in the outer peripheral portion of the gasket main body 12 (the connecting portion 13b is fitted into the annular concave portion 12c), and only the end (inner peripheral end) of the connecting portion 33 is gasket. It is connected to the outer peripheral end of the main body 32. Therefore, in order to increase the connection strength between the gasket main body 32 and the fluororesin molded body 33, for example, as shown in FIG. It is preferred that the joint area be made as large as possible. This applies to the fourth and fifth gaskets 41 and 51 described later. As described above, by changing the shape of the fluororesin molded body 33, a ferrule having a special shape can be obtained.
It can be applied to piping flanges. The structure, the manufacturing method, and the manner of attachment to the joint portion of the third gasket 31 are the same as those of the first gasket 11 except for the points described above.

FIGS. 11 and 12 show a fourth embodiment, in which a gasket made of a porous fluororesin of the present invention (hereinafter referred to as a "fourth gasket 4") is used.
1 ") are the first to third gaskets 11, 21, 3
Instead of the annular fluororesin moldings 13, 23, 33 as in 1, a tongue-shaped fluororesin molding 43 is integrally connected to the outer periphery of a gasket body 42 which is a flat annular plate. The fluorine resin molded body 43 is
Is projected between the pipe flanges when the pipe is pressed between the pipe flanges. Except for this point, the configuration of the fourth gasket 41 is the first or third gasket 11,3.
Same as 1. The molding of the fluororesin molded body 43 and the connection to the gasket main body 42 are also performed by the same method (injection molding) as that of the first or third gasket 11, 31. Although the fourth gasket 41 does not have the positioning function as the first to third gaskets 11, 21 and 31, the gasket main body 42 is held between the pipe flanges by holding the fluororesin molded body 43 by hand. And the first to third gaskets 11, 21, 31
Similarly to the above, the gasket mounting operation can be performed accurately and easily. Even in a conventional gasket made of only porous PTFE, a portion corresponding to the above-mentioned fluororesin molded body 43 can be formed. However, it is difficult to position the gasket by holding such a portion by hand. Due to the strength of the part, it is difficult to cause local deformation.

FIGS. 13 to 15 show a fifth embodiment. A gasket made of a porous fluororesin (hereinafter referred to as a "fifth gasket 51") according to the present invention in this embodiment is shown in FIG. , Bolts 8a... And nuts 8b... Are annular gaskets to be loaded between the pipe flanges 9a and 9b. The gasket main body 52 is a flat annular plate and an annular plate integrally connected to the outer periphery thereof. And a certain fluorine resin molded body 53. The fluororesin molding 53 is molded by the same method (injection molding) as the first gasket 11 and is integrally connected to the outer periphery of the gasket main body 52.
It is slightly thinner. That is, the thickness of the fluororesin molding 53 is set so as to substantially match the thickness when the gasket body 52 is properly compressed by fastening the pipe flanges 9a and 9b, and the fluorine between the pipe flanges 9a and 9b. It is devised so that the resin molding 53 does not cause inconvenience such as insufficient tightening surface pressure of the gasket main body 52 due to the interposition of the resin molding 53. Further, bolt insertion holes 53a are formed in the fluororesin molded body 53, and the bolts 8a are inserted into the bolt insertion holes 53a, so that the fifth gasket 51 is connected to the pipe flanges 9a, 9b as shown in FIG. It is devised to be positioned at an appropriate position concentric with the above. Therefore, the nut 8b screwed to each bolt 8a is tightened in a state where the fluororesin molded body 53 is inserted and supported in each bolt 8a, so that the fifth gasket 51 is concentrically sandwiched between the pipe flanges 8a and 8b. As a result, the gasket mounting operation can be performed efficiently and properly. Moreover, since the bolt insertion holes 53a are formed in the hard fluororesin molded body 53, the soft porous fluororesin portion (porous P
Unlike the conventional gasket formed in the TFE portion), there is no possibility that the bolt insertion hole portion will be damaged during the positioning operation by inserting the bolts 8a. Also,
In the fifth gasket 51, the fluororesin molded body 53 is a part involved in the sealing function, that is, a part sandwiched between the pipe flanges 8a and 8b, but as described above, the fluororesin molded body 53 is connected to the gasket main body 52. By making the thickness slightly thinner, the presence of the fluororesin molding 53 does not hinder the sealing function of the gasket main body 52.

FIGS. 16 and 17 show a sixth embodiment. The gasket made of porous fluororesin according to the present invention (hereinafter referred to as "sixth gasket 61") according to the sixth embodiment is shown in FIG. The annular gasket main body 62 is divided into a small-diameter portion 62a and a large-diameter portion 62b, and the two portions 62a and 62b are integrally connected by a thinner annular fluororesin molding 63. By the way, in a gasket loaded between a mouth of a container for storing a chemical, a solvent, and the like and a lid screwed thereto, as in the first to fifth gaskets 11, 21, 31, 41, and 51, as shown in FIG. When the fluororesin moldings 13, 23, 33, 43, 53 projecting from the outer peripheral portions of the gasket bodies 12, 22, 32, 42, 52 are provided, the presence of the fluororesin molded bodies 13, 20, 33, 43, 43, 53 can be determined by the attachment and detachment of the lid to the container opening and the gasket. However, such a problem does not occur if the gasket 61 is configured like the sixth gasket 61.
In addition, the strength and durability of the entire gasket including the gasket main body 62 are improved due to the presence of the fluororesin molded body 63. Of course, depending on the shape of the gasket-loaded portion and the sealing conditions, it may be preferable that the small-diameter portion 62a be formed in a disk shape instead of an annular shape. Like the sixth gasket 61, in the gasket according to the present invention, a portion (gasket main body 62) composed of a porous fluororesin (porous PTFE or porous PFA) is divided into a plurality of portions 62a, 6a.
2b, the parts 62a and 62b can be connected by one or more fluororesin molded bodies 63. In this case, if the fluororesin molded body 63 is a part involved in the sealing function, it is necessary to make the porous fluororesin part thinner in consideration of the compression amount of the part.

The gasket of the present invention may be configured so as to be able to reliably prevent permeation leakage from the gasket main body, which is a porous portion, by a fluororesin molded body as illustrated in FIGS. it can.

For example, the gasket according to the present invention in the seventh embodiment shown in FIGS.
In the first gasket 11, a portion of the first gasket 11 that directly contacts the sealed fluid flowing through the sanitary pipes 4a, 4b, that is, an inner peripheral portion of the gasket 71 is formed of the fluororesin molded body 73, and the gasket main body 12 is formed. It is devised so as to surely prevent the leakage of water from the air. That is, in the seventh gasket 71, FIG.
As shown in the figure, an annular fluororesin molded body 73 is integrally connected to the inner peripheral portion of the gasket main body 12. The fluororesin molded body 73 is extremely thin so as not to hinder the flexibility of the gasket main body 12, and is formed by the above-described injection molding similarly to the fluororesin molded body 13 connected to the outer peripheral portion of the gasket main body 12. Can be formed. The connection between the fluororesin molded body 73 and the inner peripheral portion of the gasket main body 12 can be made strong by the anchoring effect by injection molding. Of course, the formation of the fluororesin molded body 73 can also be performed by a method such as coating. The configuration of the seventh gasket 71 is the same as that of the first gasket 11, except that the thin annular fluororesin molded body 73 is provided.

If the surface layer of the inner peripheral portion of the gasket is made of the fluororesin molded body 73, the gasket main body 12 is made of a porous material (porous PTFE or porous PTFE) because the portion 73 is non-porous. Even if the gasket is made of porous PFA), the leakage from the inner periphery of the gasket is effectively prevented by the fluororesin molding 73. The fluororesin molded body 73 constituting the inner peripheral surface layer of the gasket 71 is harder than the gasket main body 12, but is extremely thin and is only a very small part directly touched by the sealed fluid. Therefore, depending on the presence of the fluororesin molded body 73, the original characteristics (flexibility, adaptability, restorability, etc.) of the porous fluororesin as a whole gasket are not impaired at all.

The effect of preventing permeation leakage due to such a film-like fluororesin molded body 73 is shown in FIG.
By making the shape as 0 or as shown in FIG. 21, it will be more effective. That is, in the structure shown in FIG. 20, the fluororesin molded body 73 is formed so as to have a middle-to-high cross-sectional shape with a thick central portion. In this way, when the gasket 71 is compressed in the thickness direction (pressed by the ferrules 4a and 4b), the fluororesin molding 7
3 is easily deformed as compared with the central thick portion, the presence of the fluororesin molded body 73 is
Thus, adverse effects on the elastic properties (flexibility, conformability, etc.) of No. 2 can be sufficiently eliminated. Also, the fluororesin molded body 7
By setting the cross-sectional shape of the gasket main body 3 to the above-described middle-high shape, the joining area between the gasket main body 12 and the fluororesin molded body 73 is increased, and the connection strength between the two bodies 12, 73 when the part 73 is formed by injection molding. Can be further enhanced. In FIG. 21, the fluororesin molded body 73 has a U-shaped cross section which covers the inner peripheral surface of the gasket main body 12 and both side surfaces connected thereto. By making the fluororesin molded body 73 into such a shape, it is possible to more effectively prevent the leakage of permeation,
The connection strength between the fluorine resin molded body 73 and the gasket main body 12 can be further increased by the same manufacturing method (injection molding) as that of the first gasket 11. Of course, the gasket body 12
Under a sealing condition in which the outer peripheral portion of the substrate directly contacts the fluid to be sealed, a thin fluororesin molded body is connected to the outer peripheral portion.

The gasket body may have a different thickness as described above or a shape separated into a plurality of portions depending on the sealing conditions and the like, and may have a mixture of dense and dense portions (portions having different porosity). You can keep.

[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 first gasket.

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

FIG. 3 is a longitudinal sectional side view showing a manufacturing process of a first gasket.

FIG. 4 is a longitudinal sectional side view showing a state in which a first gasket is attached to a joint of a sanitary pipe.

FIG. 5 is a front view showing a second gasket.

FIG. 6 is a vertical sectional side view taken along the line VI-VI of FIG. 5;

FIG. 7 is a longitudinal sectional side view showing a manufacturing process of a second gasket.

8 is a vertical sectional side view showing a part of a manufacturing process when a second gasket is obtained by a method different from the manufacturing method shown in FIG. 7;

FIG. 9 is a longitudinal sectional side view showing a state in which a second gasket is attached to a joint of a sanitary pipe.

FIG. 10 is a longitudinal sectional side view of a partially cutaway showing a third gasket.

FIG. 11 is a half-cut front view showing a fourth gasket.

FIG. 12 is a longitudinal sectional side view of a main part taken along line XII-XII in FIG. 11;

FIG. 13 is a half front view showing a fifth gasket.

FIG. 14 is a longitudinal sectional side view of a main part taken along line XIV-XIV in FIG. 13;

FIG. 15 is a longitudinal sectional side view showing a state in which a fifth gasket is attached to a joint of a sanitary pipe.

FIG. 16 is a front view showing a sixth gasket.

FIG. 17 is a cross-sectional plan view of a main part along the line XVII-XVII in FIG. 16;

FIG. 18 is a vertical sectional side view showing a seventh gasket.

FIG. 19 is a longitudinal sectional side view showing a state in which a seventh gasket is attached to a joint of a sanitary pipe.

FIG. 20 is a vertical sectional side view showing a modification of the seventh gasket.

FIG. 21 is a vertical sectional side view showing another modification of the seventh gasket.

[Explanation of symbols]

1a, 1b, 2a, 2b: injection mold, 1c, 2c: cavity, 1d, 2d: void, 3: fluorine resin material, 4a,
5a: sanitary piping, 5a, 5b: ferrule, 8a,
8b: bolt, 9a, 9b: pipe flange, 11: first
Gasket (gasket made of porous fluororesin), 12,
22, 32, 42, 52, 62 ... gasket body, 12
a, 12b, 23d, 23e ... ridge, 12c, 23c ...
Recessed portions, 13, 23, 33, 43, 53, 63, 73 ... fluororesin molded bodies, 13a, 23a ... positioning engagement portions, 21
… Second gasket (gasket made of porous fluororesin),
31: third gasket (gasket made of porous fluororesin), 41: fourth gasket (gasket made of porous fluororesin), 51: fifth gasket (gasket made of porous fluororesin), 61: sixth gasket (Gasket made of porous fluororesin), 62: gasket main body, 62a: small diameter portion, 62b: large diameter portion, 71: seventh gasket (gasket made of porous fluororesin).

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[Procedure amendment]

[Submission date] December 20, 1999 (1999.12.
20)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

[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.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction contents]

[0009]

SUMMARY OF THE INVENTION The present invention provides a gasket made of a porous fluororesin, in order to achieve the above object.
In particular, the gasket body made of porous fluororesin
To connect non-porous fluororesin moldings molded with polyester resin
In this way, it is proposed that one or more parts are formed of a nonporous fluororesin molded body. Fluorine resin molding of the non-porous mentioned here, part of the porous fluorine resin configured gasket present (e.g., the portion in direct contact with the sealed fluid) by melting and solidifying or pressurized圧固the Non-porous materials are not included.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J040 AA01 AA12 BA01 EA16 FA07 FA08 HA15 4F100 AK17A AK17B AK18A AK18B AK19A AN02A BA02 DJ00B GB90 4H017 AA04 AB12 AC16 AD01 AE02

Claims (7)

[Claims] 1. A gasket made of a porous fluororesin, wherein a part or a plurality of parts are constituted by a nonporous fluororesin molded body. 2. The gasket made of a porous fluororesin according to claim 1, wherein a part of the gasket related to a sealing function is made of a non-porous fluororesin molded body. . 3. The porous fluororesin according to claim 1, wherein a portion of the gasket that directly contacts the sealed fluid is made of a nonporous fluororesin molded body. Gasket. 4. A gasket having an annular plate shape,
4. The porous fluorine according to claim 1, wherein an inner peripheral portion, an outer peripheral portion, or an inner and outer peripheral portion of the gasket is formed of a non-porous fluororesin molded body. Gasket made of resin. 5. The gasket according to claim 1, wherein a part or a part of the gasket that does not participate in the sealing function is made of a non-porous fluororesin molded body. A gasket made of the porous fluororesin according to claim 4. 6. The porous fluorine resin according to claim 1, wherein the porous fluorine resin is porous PTFE or porous PFA. Gasket made of resin. 7. As a constituent material of a nonporous fluororesin molding,
At least PCTFE, FEP, PFA, ETFE, E
CTFE, PVDF, VDF-HFP copolymer, VDF
2. A fluororesin selected from the group consisting of -HFP-TFE copolymer, CTFE-VDF copolymer, TFE-PP copolymer and vinylidene fluoride-based fluororubber is used. The gasket made of a porous fluororesin according to claim 2, claim 3, claim 4, claim 5, or claim 6.