JP2581010Y2 - Fluoroplastic wrapped gasket - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to the improvement of a fluorine resin wrapped gasket in which the outer periphery of a core body as a cushioning material is covered with a fluorine resin film, and more specifically, to the use of fluorine at high temperature and high pressure. The present invention relates to a fluorine resin wrapped gasket that prevents the flow of a resin film.

Technical background of the invention This kind of fluororesin-wrapped gasket is, for example,
As shown in the figure, a joint sheet, asbestos, rubber, cork, or an annular core 2 which is a combination thereof is used as a cushioning material, and the outer periphery of the annular core 2 is made of a heat-resistant material such as a tetrafluoroethylene resin. It has a structure covered with a fluorine resin film 4 having excellent chemical properties. Therefore, this type of gasket is often used as a gasket to seal between flanges of piping, especially for highly aggressive chemical fluids,
Alternatively, it is widely used as a gasket for the food industry or pure water to avoid contamination.

However, when the fluororesin-coated gasket is used at a high pressure or a high temperature, the fluororesin film 4 covering the outer periphery of the annular core body 2 causes a flow (flow) in sequence due to the tightening pressure, and the gasket in use is not used. There is a possibility that the tightening pressure decreases and the sealing surface pressure becomes insufficient, which causes fluid leakage. In order to prevent this, when retightening is performed, the fluororesin film thinned by the flow may be broken.

In order to prevent this flow, various types of gaskets wrapped with fluororesin have been proposed.

For example, in the gasket described in Japanese Utility Model Publication No. 47-29856, a packing body is formed by laminating a joint sheet on both sides of an inorganic fiber plate made of an inorganic fiber such as asbestos with a rubber-based adhesive. There is known a gasket in which an annular wire mesh is disposed on both sides of the wire mesh, and a fluororesin jacket made of a fluororesin film such as PTFE is provided on the outside of the wire mesh.

Further, in Japanese Patent Application Laid-Open No. 55-72950, a thermosetting resin-impregnated glass cloth is laminated on both surfaces of at least one cushion material made of a heat-resistant felt mat or cloth to be integrated, and this integration is performed. A gasket wrapped with a fluororesin in which the formed core is covered with a PTFE jacket has also been proposed.

However, focusing on the minute portion at the interface with the core body of the fluororesin jacket, in any of the gaskets of the above proposals, flow may occur at the minute portion at this interface, and as a result, airtightness is maintained. The existing seal line was broken and leaked, so that high sealing performance could not be obtained stably.

As described above, even with the new proposal described above, the flow of the minute portion cannot be prevented, and the flow of the fluororesin jacket cannot be effectively prevented.

In addition, in the wrapping gasket proposed above, since the wire mesh is disposed on both sides of the packing body as the core body, the flexibility of the core body is lost, and the undulation (or “ It is difficult to absorb "distortion"), and there is a possibility that the sealing performance may be reduced. Also,
When the gasket is tightened, especially at high temperatures,
There is a possibility that the fluororesin jacket may be broken by the wire in the wire mesh. In particular, since the intersection of the gold wires bites into the fluororesin jacket, the jacket may be destroyed at this portion.

On the other hand, in the above proposal, the glass fiber is disposed in the core body. However, when the glass fiber reaches a temperature of 100 ° C. or more, the tensile strength decreases, and when the glass fiber is used for the gasket, the tightening surface pressure is reduced. Load laterally of the fiber,
The glass fiber which is weakened in strength and becomes brittle at high temperatures is broken, and as a result, stress relaxation is increased, the flow prevention effect is lost, and there is a possibility that the sealing performance is also lowered.

As described above, the new proposal described above not only cannot effectively prevent the flow, but also has a risk of reducing the sealing performance for various reasons.

The purpose of the present invention is to prevent the flow in the minute part of the fluororesin jacket effectively by firmly fixing the fluororesin jacket and the core over a minute part when using high temperature and high pressure, It is an object of the present invention to provide a fluororesin-wrapped gasket capable of preventing a decrease in sealing performance due to a reason and maintaining a sealing function for a long period of time.

SUMMARY OF THE INVENTION The fluororesin-wrapped gasket according to the present invention is a fluororesin-wrapped gasket obtained by fitting an annular core in an annular structure of a fluororesin jacket, wherein the annular core is used at a high temperature and a high pressure. And a powder layer made of a powder having a fine particle diameter capable of firmly fixing the fluororesin jacket and the fluororesin jacket is interposed between the fluororesin sheath and the annular core.

According to such a gasket wrapped with a fluororesin according to the present invention, since a powder layer made of a powder having a fine particle diameter is interposed between the fluororesin sheath and the annular core, the gasket can be used at a high temperature and a high pressure. The fluororesin jacket and the core body can be firmly fixed, especially even in a minute portion, whereby the flow in the minute portion in the fluororesin jacket can be effectively prevented.

In addition, since the flexibility of the gasket is not lost, the fluororesin jacket fits well on the flange surfaces, and the gap between the flange surfaces can be properly closed, and the flanges can be sealed well.

Therefore, a decrease in sealing performance can be effectively prevented, and the sealing function can be maintained for a long period of time.

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 is a sectional view of a main part of a gasket wrapped with a fluororesin according to an embodiment of the present invention.

The fluororesin-wrapped gasket 10 shown in FIG. 1 has an annular core 12 and a fluororesin jacket 14 having an annular groove 13 in which the core 12 is mounted.

The core 12 is made of an asbestos plate, a rubber plate, a cork plate, a joint sheet material, or the like.

The fluororesin jacket 14 is made of tetrafluoroethylene resin (PTF
E), ethylene tetrafluoride-perfluoroalkyl vinyl ether copolymer resin (PFA), ethylene tetrafluoride-propylene hexafluoride copolymer resin (FEP), ethylene tetrafluoride
It is composed of fluororesins such as propylene hexafluoride-perfluoroalkyl vinyl ether copolymer resin (EPE), ethylene tetrafluoride-ethylene copolymer resin (ETEE) and vinylidene fluoride resin (PVDF). , PFA
And the like. Although the fluororesin jacket 14 shown in FIG. 1 has the annular groove 13 whose outer periphery is open, the present invention is not limited to this, and the outer periphery may be closed.

A powder layer 16 made of powder having a small particle size is interposed between the fluororesin jacket 14 and the core 12. This powder layer
16, dipped powder dispersed in water or non-aqueous solution,
It is uniformly attached to the surface of the core body 12 by spraying, coating or the like. At this time, if necessary, a small amount of a thickener or an adhesive may be used.

The particle size of the powder is preferably 100 μm or less, particularly 1.0 μm.
Those having a size of μm or less are more preferable. The particle size does not need to be uniform, and may vary.

The thickness of the powder layer 16 is preferably 1 mm to 0.01 μm,
More preferably, it is 100 μm to 0.1 μm.

As a material of the powder, an inorganic powder (titanium oxide, talc, barium sulfate, calcium carbonate, clay, or the like) is preferable, and a resin powder such as a fluororesin may be used.

The shape of this powder may be various shapes such as columnar, needle-like, cubic, orthorhombic, such as potassium titanate and wollastonite, but scale-like, such as mica, is less effective. , Titanium oxide and barium sulfate are desirable. In addition, the greater the adhesiveness or the cohesiveness of the powder, the greater the fixing effect described later.

This powder layer 16 is interposed between the core 12 and the fluororesin jacket 14 and adheres to both interfaces, so that
When the high pressure is used, the core 12 and the fluororesin jacket 14 can be firmly fixed. As a result, the flow of the fluororesin jacket 14 can be prevented, and the sealing performance can be improved at high temperature and high pressure.

The following are conceivable factors for the fixation by the powder layer 16. Van der Waals force (sum of interactions between constituent atoms and molecules), electrostatic force, reaction of functional group on powder particle surface, physical anchor effect (fluorine resin on contact surface with powder) Plastic deformation), an increase in the area of the interface, and the like.

As described above, since the micro-order powder is interposed between the surface of the core body 12 and the fluororesin casing 14, the fluororesin casing and the core body are firmly secured over a minute portion when high temperature and high pressure are used. And the flow of minute portions of the fluororesin jacket can be effectively prevented.

In addition, since the flexibility of the gasket is not lost, the fluororesin jacket fits well on the flange surfaces, and the gap between the flange surfaces can be properly closed, and the flanges can be sealed well.

Therefore, a decrease in sealing performance can be effectively prevented, and the sealing function can be maintained for a long period of time.

The present invention is not limited to the above-described embodiment, and can be variously modified.

For example, as shown in FIG. 2, a cushion member 18 may be interposed between the core 12 and the fluororesin jacket 14. As the cushion material 18, a felt material made of asbestos, rock wool, glass fiber, carbonized fiber, or the like is used.
The thickness of the cushion material 18 is 50 to
It is preferably in the range of 300%.

In the case of this embodiment, powder is adhered to the cushion material 18, and the powder layer 16 is interposed between the fluororesin jacket 14 and the cushion material 18. Thereby, the fluororesin jacket 14 and the cushion member 18 can be firmly fixed at the time of using high temperature and high pressure. In this case, the powder does not adhere to the cushioning material by post-processing, but the powder appears on the surface of the cushioning material 18 by blending the powder with the cushioning material 18 such as a felt material. You may do it.

Further, in the present invention, as shown in FIG. 3, two annular cores 12a, 12a are used, and a metal cushion 2 is provided therebetween.
0 may be interposed. Metal cushion20
For example, a plate material obtained by processing a spring steel material, a cold-rolled steel material, a stainless steel material, or the like into a corrugated shape is used.

Also in this embodiment, a powder layer 16 is interposed between the fluororesin jacket 14 and the cushion material 18. Further, the cushion 20 imparts good elasticity to the core body 12a, so that the conformability of the gasket 10 to the flange surface or the like is further improved.

Effect of the present invention As described above, in the present invention, since the powder layer made of fine particle diameter powder is interposed between the fluororesin jacket and the annular core, the fluorine is used when high temperature and high pressure are used. The resin jacket and the core body can be firmly fixed, especially in a minute portion, and the occurrence of a flow in the minute portion in the fluororesin jacket can be effectively prevented. In addition to this, it is possible to prevent the deterioration of the sealing performance due to various reasons. Therefore, a decrease in sealing performance can be effectively prevented, and the sealing function can be maintained for a long period of time.

(Examples) Hereinafter, the present invention will be described based on more specific examples, but the present invention is not limited to these examples.

Example An experiment was conducted on the high-temperature cycle sealing performance of the gasket wrapped with fluororesin shown in FIG.

The outer diameter of this fluororesin-wrapped gasket was 159 mm, the inner diameter was 116 mm, and the overall thickness was 3.2 mm. Barium sulfate was used for the powder layer, and the thickness of the powder layer was about 1.0 μm.

As an experiment, the initial tightening stress σg = 250 kgf / cm ² , the sealing fluid: nitrogen gas, the airtightness limit when the pressure was increased by 5 kgf / cm ² at 200 ° C × 48 hr × 3 cycles, and the experiment of high-temperature cycle sealing performance Was done.

FIG. 6A shows an integrated type particle size distribution graph (weight basis) of the powder layer of the gasket according to this experiment. This gasket has 70% powder with a particle size of 0.3 μm or more, and 0.3 μm
30% of the powder had a particle size of not more than m. Further, the differential type particle size distribution graph (weight basis) of the powder layer is shown in FIG.
Shown in This graph shows the ratio of powder having another particle size when the ratio of powder having a particle size of 0.5 to 0.6 μm is taken as 100%.

 The results of this experiment are shown in FIG.

Comparative Example As a comparative example, an experiment was performed on the high-temperature cycle sealing performance under the same conditions as in the example, with respect to the hermetic limit of the same fluororesin-wrapped gasket as in the above example except that the powder layer was not provided. .

FIG. 5 shows the experimental results of this comparative example together with the experimental results of the example.

The experimental results of the evaluation Examples and Comparative Examples, while the air-tight pressure of the gasket according to the comparative example was approximately 20 kgf / cm ^2,
The gas-tight pressure of the gasket according to the example was approximately 30 kgf / cm ² . As described above, it was confirmed that the provision of the powder layer improved the hermetic pressure by approximately 10 kgf / cm ² and significantly improved the sealing performance.

[Brief description of the drawings]

FIG. 1 is a partial perspective view including a cross section of a main part of a fluororesin wrapped gasket according to one embodiment of the present invention, and FIGS. 2 and 3 are main parts of a fluororesin wrapped gasket according to another embodiment of the present invention. FIG. 4 is a cross-sectional view of a conventional fluororesin-wrapped gasket, FIG. 5 is a graph showing experimental results of sealing performance of the fluororesin-wrapped gasket according to the present invention, and FIGS. It is a graph which shows the particle size distribution of the powder layer of the fluororesin wrapping gasket which concerns on invention. 10: Fluororesin wrapped gasket 12: Core, 13 ... Annular groove 14 ... Fluororesin jacket, 16 ... Powder layer 18 ... Cushion material 20 ... Metal cushion

Claims (4)

(57) [Scope of request for utility model registration] 1. A fluorine resin-enclosed gasket comprising a ring-shaped core inserted into an annular groove of a fluorine-containing resin jacket, wherein the ring-shaped core and the fluorine-containing resin jacket are separated when used under high temperature and high pressure. A fluororesin-wrapped gasket, characterized in that a powder layer made of a powder having a fine particle diameter that can be firmly fixed is interposed between the fluororesin sheath and the annular core. 2. The gasket according to claim 1, wherein the powder has a particle size of 100 μm or less. 3. The gasket according to claim 1, wherein a cushion material is interposed between the annular core and the powder layer. 4. The gasket according to claim 1, wherein an annular metal cushion is interposed between the two annular cores.