JPS6220971A - Sealing material - Google Patents

Abstract

PURPOSE:To seal liquid or gaseous chemicals by covering an elastic layer with a chemicals-resisting layer together with covering the chemicals-resisting layer with a fine-fiber-structured porous layer made of tetra-fluoroethylene resin. CONSTITUTION:The sealing material is made up of a three-layered structure: an elastic body layer 1, a core part 1, a plastic layer 2, an intermediate layer, and a PTFE-made porous layer 3, the outer most layer. It is most appropriate to form the elastic layer 1 by using rubber material such as nitrile rubber, natural rubber, or silicone rubber. The plastic layer 2, which covers the elastic body 1, is formed by means of PE, PP, FEP, etc. In addition, the outermost PTFE-made porous layer 3 is made up of fine-fiber-structure formed by nodes, which are connected with each other by fibers. The mean diameter and porosity of the porous layer 3 is set at 0.1-10mum and 30-95%, respectively.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a sealing material, and more specifically, to a sealing material that covers an elastic layer with multiple layers, and which is particularly resistant to four chemicals. Regarding.

<Conventional technology> Conventionally, as a sealing material used as a hatch packing for a chemical tanker, etc., as shown in FIG. The rubber layer (10) is covered with a braid (11) of resin (PTFE) thread, or as shown in Figure 3, the rubber layer (10) is covered with a braid (12) of polypropylene (PP) thread. It is provided that the outer periphery of the braid (12) is covered with a braid (11) of PTFE yarn impregnated with oil.

<Problems to be Solved by the Invention> However, although all of the above sealing materials may exhibit a certain degree of chemical resistance, even though they are impregnated with oil, liquid or gaseous chemicals may Braiding of PTFE yarn (
11) It was easy to penetrate into the interior through the stitches, making it difficult to exhibit complete chemical resistance. Therefore, in extreme cases, the internal rubber layer (10) may deteriorate due to chemicals and lose its function as a sealing material. Furthermore, the braided PTFE yarn (11) has problems in that it has poor elasticity, poor adhesion to the sealing surface, and is easily damaged.

This invention was made in view of the above-mentioned problems, and aims to provide a sealing material that prevents chemicals from penetrating inside, exhibits good chemical resistance, and is resistant to damage. .

Means for Solving Problems> To achieve the above object, the sealing material of the present invention covers the periphery of the elastic layer with a chemical-resistant plastic layer, and also covers the outer periphery of the plastic layer. , minute consisting of nodules connected to each other by fibers! It is covered with a porous PTFE layer having an IN structure.

However, the above-mentioned PTFE porous material layer preferably has an average pore diameter of 0.1 to 10 μm and a porosity of 30 to 95%, and the plastic layer preferably has a crosslinked PE, PP, or Fluoroalkoxyethylene (PFA)
), tetrafluoroethylene/hexafluoropropylene (FEP)
It is conceivable to construct it with a shrinkable tube made of any of the following.

Effect> According to the above-mentioned sealing material, the PTFE porous layer has a fine fibrous structure, and since P'rFE itself has water repellency, the chemical solution does not penetrate the pores of the PTFE porous layer. Therefore, the PTFE porous layer can prevent the chemical solution from penetrating inside. Further, the plastic layer can prevent gaseous chemicals that can permeate the PTFE porous body from entering the interior.

In particular, the average pore diameter of the PTFE porous layer is 0.1 to 10#.
By setting I to a small value, penetration of the chemical solution can be more completely prevented, and by setting the porosity to 30 to 95%, good elasticity can be imparted to the porous body. . Furthermore, when the plastic layer is composed of a crosslinked shrink tube made of PE, PP, PFA, or FEP, the plastic layer itself can exhibit excellent chemical resistance, and
It is also suitable for manufacturing.

<Example> Embodiments will be described in detail below with reference to the accompanying drawings showing embodiments.

FIG. 1 is a sectional view showing the sealing material of the present invention. The above sealing material includes an elastic layer (1) as a core, a plastic layer (2) as an intermediate layer, and a PT as an outermost layer.
It is formed into a three-layer structure including an FE porous material layer (3).

The elastic layer (1) is best formed from a rubber material such as nitrile rubber, natural rubber, styrene-butadiene rubber, silicone rubber, etc. In addition, it can also be formed from an elastomer such as perbrene or urethane. . In addition, the plastic*(2) covering the periphery of the elastic layer (1)
] is preferably made of PE, PP, PFA, FEP, etc. from the viewpoint of chemical resistance, and in particular, it is preferable from the viewpoint of manufacturing and quality to be made of a shrink tube made of the above-mentioned radiation-crosslinked plastic. .

Furthermore, as the outermost PTFE porous layer (3),
It is composed of a fine fibrous structure consisting of nodules connected to each other by fibers, and its average pore size is 0.1 to 10/2.
It is preferable to set ffi and porosity to 30 to 95%, respectively. Such a P T F E porous material layer (
In order to produce 3), the method described in Japanese Patent Publication No. 42-13560 can basically be used.

That is, first, a PTFE unsintered powder mixed with a liquid lubricant is molded by extrusion, rolling, etc., and the liquid lubricant is removed from the molded product by means such as extraction and heating evaporation, or is left unremoved. , stretching the molded product in at least one axial direction. Then, by heating to a sintering temperature of about 321° C. or higher while preventing heat shrinkage and sintering and fixing the stretched structure, a porous PTFE body with improved strength can be obtained.

Note that the heat shrinkage-prevented state includes not only a state in which shrinkage is completely prevented, but also a state in which some shrinkage is allowed. The PTFE porous material obtained in this way has a microstructure consisting of very thin fibers and nodules connected to each other by the fibers, and the fiber diameter and length, the size of the nodules, Since their number can be changed depending on the stretching and sintering conditions, the pore diameter and porosity of the porous body can be set freely. The porous body having the above-mentioned microstructure has particularly excellent mechanical strength and is suitable as the sealing material of the present invention.

With the above configuration, since the porous PTFE body FB (3) has water repellency and has a fine fiber structure, it is possible to prevent the chemical solution from permeating the porous PTFE body layer (3). In addition, in Plastic I (2), PT
Gaseous chemicals that have permeated the FE porous layer (3) can be prevented from further invading the interior.

Therefore, the elastic layer (1) of the core can be reliably protected from chemicals.

In particular, the porous PTFE layer (3) with an average pore size of 0.1 to 10μ can more completely prevent the penetration of chemical solutions, and the porous PTFE layer (3) with a porosity of 30 to 95%
E The porous body layer (3) can have appropriate elasticity at a predetermined thickness, and as a result, the adhesion with the sealing surface can be further improved, and it is a suitable layer that is less likely to be damaged. Become.

Note that the sealing material of this invention is not limited to the above-mentioned embodiments; for example, the cross-sectional shape may be implemented in various shapes depending on the application, and the gist of this invention may be modified. Various design changes can be made within the scope.

<Effects of the Invention> As described above, according to the sealing material of the present invention, PTF
The E porous layer blocks liquid chemicals, and the Plus Deck layer blocks gaseous chemicals that have passed through the PTFE porous layer, reliably protecting the deep elastic layer from chemicals. Moreover, it has the unique effect of having a suitable elasticity, excellent adhesion to the sealing surface, and being resistant to damage.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the sealing material of the present invention, and FIGS. 2 and 3 are cross-sectional views showing conventional sealing materials. (1)...Elastic layer (a...Plastic layer (3)...PTFE porous layer Patent applicant Sumitomo Electric Industries, Ltd. Figure 1

Claims (1)

[Claims] 1. The periphery of the elastic layer is covered with a chemical-resistant plastic layer, and the outer periphery of the plastic layer is covered with a polytetrafluoride fine fiber structure consisting of nodules interconnected by fibers. A sealing material characterized by being covered with an ethylene resin porous layer. 2. The average pore diameter of the polytetrafluoroethylene resin porous layer is 0.
The sealing material according to claim 1, which has a porosity of 1 to 10 μm and a porosity of 30 to 95%. 3. The sealing material according to claim 1, wherein the plastic layer is a shrinkable tube made of crosslinked polyethylene, polypropylene, perfluoroalkoxyethylene, tetrafluoroethylene, or hexafluoropropylene.