JP2001280504A - Rubber gasket structure and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber gasket structure for a diaphragm type electrolytic bath which is superior in sealability, heat resistance and durability. SOLUTION: This rubber gasket structure A comprises a frame-like gasket 4, and a frame-like fluororesin member 6, stuck integrally to the inner circumferential face of the gasket 4 in vulcanization molding of the rubber gasket 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gasket structure used for preventing fluid leakage in a wide range of fields such as piping and equipment, and particularly to a large-sized gasket suitable for a diaphragm type electrolytic cell. The present invention relates to an improvement in a rubber gasket structure and a manufacturing method thereof.

[0002]

2. Description of the Related Art A general diaphragm type electrolytic cell is shown in FIG. In the drawing, a diaphragm type electrolytic cell is composed of a plate 1 and a diaphragm 2
And a frame-shaped rubber gasket 4 is disposed between each electrode 3 and the plate 1 or the diaphragm 2. An anode compartment is defined.

A frame-shaped rubber gasket 4 used in the above-mentioned diaphragm type electrolytic cell plays an important role for sealing an internal fluid (electrolyte solution) and insulating between electrodes, and a frame as shown in FIG. A molded product having a rectangular shape and a rectangular cross section is often used.

The rubber gasket 4 is generally formed by cross-linking and molding a rubber compound mainly composed of rubber and carbon black. The rubber used is ethylene propylene rubber (EPM or EPDM).
And acrylonitrile butadiene rubber (NBR) are properly used depending on the type and temperature of the electrolytic solution.

[0005]

However, in recent diaphragm type electrolytic cells, the fluid temperature has been increased in order to improve the decomposition efficiency, and the gasket replacement time has been extended in order to reduce the maintenance cost. Gaskets tend to be more demanding, but the current mainstream EPDM rubber gaskets suffer from problems such as surface degradation due to internal fluids and leakage due to erosion, and higher heat resistance.・ It is considered difficult to improve durability.

Recently, in order to improve the chemical resistance and heat resistance of the gasket, as shown in FIG. 8, the frame-shaped gasket 4 is formed into a U-shape with a fluororesin tape 5 from the inner peripheral surface to the upper and lower surfaces. A coated gasket has been proposed, but this gasket is not molded integrally with the fluororesin tape, so the gasket is easily displaced during use. Problems may occur.

In the case where the both ends of the fluororesin tape are welded and then deformed to produce a fluororesin-coated portion,
It takes time and effort to smooth the welded portion, and there is also a problem that the production cost is increased due to the necessity of deformation of the fluororesin tape and adhesion of the fluororesin tape and the rubber gasket.

The present invention has been made to solve the above-mentioned problems, and has as its object to provide a rubber gasket structure having excellent sealing properties, heat resistance and durability as a frame-shaped rubber gasket for a diaphragm type electrolytic cell. And

[0009]

In order to achieve the above object, a rubber gasket structure according to the present invention has a frame-shaped rubber gasket, which is in contact with the inner peripheral surface and is integrally bonded at the time of vulcanization molding of the rubber gasket. The gist of the invention is that it is composed of a frame-shaped fluororesin member.

In the method of manufacturing a rubber gasket structure according to the present invention, an unvulcanized rubber material and a frame-shaped fluororesin member are placed in a mold, and the rubber material is vulcanized to form a frame-shaped rubber gasket. In addition, the gist is that the frame-shaped fluororesin member is integrally adhered to the inner peripheral surface thereof.

[0011]

Preferred embodiments of the present invention will be described below in detail with reference to the drawings. 1 and 2, A denotes a gasket structure, 4 denotes a frame-shaped rubber gasket forming the gasket structure, and 6 denotes an inner portion of the frame-shaped rubber gasket 4 extending from the upper surface of the inner peripheral portion to the lower surface of the inner peripheral portion. It is a frame-shaped fluororesin member integrally adhered to the peripheral surface by a method described later.

FIG. 5 shows an example of a method of manufacturing the gasket structure. In the figure, 7 is a press molding die, 6 is a fluororesin member molded in a frame shape in advance, and 4 ′ is an unvulcanized rubber material. After filling the unvulcanized rubber material 4 ′ into the voids left between the mold-like fluororesin member and the mold 7, vulcanization is performed by a hot press, so that FIGS. As shown in the figure, a frame-shaped fluororesin member 6 is formed on the inner peripheral surface of the frame-shaped rubber gasket 4.
Are integrally bonded to each other to obtain a gasket structure.

[0013] The type of fluororesin used in the present invention is not particularly limited. For example, polytetrafluoroethylene (PTFE), tetrafluoroethylene.
Perfluoroalkyl vinyl ether copolymer (PF
A), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), polyvinylidene fluoride (PVDF), ethylene / tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE) and the like. it can.

The type of the rubber used in the present invention is not particularly limited, and is appropriately selected according to the conditions of use. For example, ethylene propylene rubber (E
PM, EPDM), acrylonitrile butadiene rubber (NBR), hydrogenated acrylonitrile butadiene rubber (HNBR), fluoro rubber (FKM), etc. can be used. Is also possible.

Further, the crosslinking agent and the reinforcing filler compounded in the rubber are not particularly limited, and a known sulfur or peroxide-based crosslinking agent may be used as the crosslinking agent. Silica can be used in addition to carbon black, and other additives conventionally used for this type of gasket may be blended.

FIGS. 3 and 4 show another embodiment of the present invention. In order to increase the area of the bonding surface between the frame-shaped fluororesin member 6 and the rubber gasket 4, the outer peripheral surface of the frame-shaped fluororesin member 6 is made uneven. By performing the processing described above, the integrated adhesive strength between the resin and the rubber is improved, and a gasket having better handleability and durability can be obtained. The shape of this outer peripheral surface processing can be any shape in consideration of workability and adhesiveness,
There is no problem as long as it is a shape that can be formed, such as a waveform or a key, in addition to a triangle shape as shown in FIG. 3 or a square shape as shown in FIG.
Also, these shapes are not only machined later,
When a molded body of fluororesin is molded by a molding method, it can be manufactured by a method such as molding into such a shape.

As a method of manufacturing the rubber gasket structure,
First, a fluororesin sheet cut to a predetermined size is welded, or the outer peripheral portion of a rectangular frame-shaped fluororesin molded body obtained by punching from the sheet is cut with a lathe or the like to form a frame-shaped fluororesin member. As shown in FIG. 5, the unvulcanized rubber material 4 ′ is placed in a mold 7 together with the frame-shaped fluororesin member 6, and molded by a hot press or the like to form the frame-shaped fluororesin member 1. A body-shaped rubber gasket structure can be easily obtained. If necessary, the gasket structure may be subjected to secondary crosslinking using an oven.

Further, the surface of the frame-shaped fluororesin member to be bonded to rubber is preferably subjected to an appropriate surface treatment. For example, a complex compound solution obtained by adding sodium metal to a tetrahydrofuran solution of naphthalene can be used. Thereby, the adhesion between the frame-shaped fluororesin member 6 and the rubber gasket 4 can be further improved.

Further, an adhesive, for example, a commercially available vulcanizing adhesive for rubber containing a silane coupling agent or the like can be applied in advance to the surface of the frame-shaped fluororesin member to be bonded to the rubber gasket. It is also possible to use both an adhesive and an adhesive.

[0020]

Hereinafter, embodiments of the present invention will be described in detail.
The present invention is not limited to this embodiment.

Example 1 A 3 mm-thick polytetrafluoroethylene (hereinafter PTF)
E) The outer circumference of the sheet is 2440 mm long and 124 wide.
0 mm, the inner peripheral side is punched into a frame shape of 2420 mm in length × 1220 mm in width and 10 mm in width, and the outer peripheral surface to be cross-linked with PTFE rubber is surface-treated with a complex compound solution formed by adding sodium metal to a tetrahydrofuran solution of naphthalene, Rubber gasket structure integrated with frame-shaped fluororesin member by performing cross-linking molding with unvulcanized rubber material in a frame-shaped mold having a length of 2500 mm x width 1300 mm on the outer side and a length of 2420 mm x width 1220 mm on the inner side and width of 40 mm. I got

Example 2 Using a frame-shaped PTFE molded member having a cross-section processed as shown in FIG. 3, a frame-shaped rubber resin member-integrated rubber gasket structure was obtained in the same manner as in Example 1.

Example 3 Using a frame-shaped PTFE molded member having a cross section processed as shown in FIG. 4, a frame-shaped rubber resin member-integrated rubber gasket structure was obtained in the same manner as in Example 1.

Comparative Example 1 A rubber alone was vulcanized and molded using the same mold as in Example 1 to obtain a frame-shaped rubber gasket.

In the above-mentioned embodiment, the frame-shaped fluororesin member is formed by stamping out a PTFE sheet.
It is also possible to use a tape obtained by butt-welding several tapes, or a pre-formed PTFE sheet can be used.

The samples of Examples 1 to 3 and Comparative Example 1 were measured for compression set by a method according to JIS K6301. Also, set in the electrolytic cell of the actual machine and
The test operation was performed for 0 hours, and deterioration and erosion of the gasket were visually determined. Table 1 shows the test results. The evaluation of the deterioration and erosion of the gasket was performed according to the criteria shown in Table 2.

[0027]

[Table 1]

[Table 2]

As can be seen from Table 1, all of Examples 1 to 3 have no gasket surface deterioration or erosion, have a small compression set, and have good characteristics as a gasket as compared with Comparative Example 1.

Although the rubber gasket for a diaphragm type electrolytic cell has been mainly described above with reference to the present invention, the rubber gasket structure of the present invention is not limited to this, and it is needless to say that other various sealing materials, especially high temperature Needless to say, it can be suitably used as a sealing material that is exposed to under or under chemicals.

[0030]

As described above, according to the present invention, a rubber gasket structure suitable for use in a diaphragm type electrolyzer without rubber deterioration or erosion even when used at high temperatures or under chemicals. can get.

[Brief description of the drawings]

FIG. 1 is a perspective view of a rubber gasket structure showing one embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of a rubber gasket structure.

FIG. 3 is an enlarged sectional view of a main part of a rubber gasket structure according to another embodiment of the present invention.

FIG. 4 is an enlarged sectional view of a main part of a rubber gasket structure according to another embodiment of the present invention.

FIG. 5 is an explanatory view showing a production example of a rubber gasket structure.

FIG. 6 is a cross-sectional view of a conventional diaphragm type electrolytic cell.

FIG. 7 is a perspective view showing a combined state of a rubber gasket and an electrode.

FIG. 8 is a sectional view of a main part showing a conventional fluororesin-coated rubber gasket.

[Explanation of symbols]

 A gasket structure 1 plate 2 diaphragm 3 electrode 4 rubber gasket 4 'unvulcanized rubber material 5 fluororesin tape 6 frame-shaped fluororesin member 7 mold

Claims (4)

[Claims] 1. A rubber gasket structure comprising: a frame-shaped rubber gasket; and a frame-shaped fluororesin member integrally bonded to an inner peripheral surface of the rubber gasket during vulcanization molding of the rubber gasket. . 2. The rubber gasket structure according to claim 1, wherein the bonding surface of the frame-shaped fluororesin member has an uneven shape. 3. An unvulcanized rubber material and a frame-shaped fluororesin member are placed in a mold, and a vulcanization treatment of the rubber material is performed to form a frame-shaped rubber gasket, and the frame-shaped rubber gasket is formed on an inner peripheral surface thereof. A method for manufacturing a rubber gasket structure, wherein a fluororesin member is integrally bonded. 4. The method for manufacturing a rubber gasket structure according to claim 3, wherein the frame-shaped fluororesin member has an irregular outer peripheral surface.