JPS6035762B2 - Materials for conductive seals - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stretched conductive sealing material that has both sealing properties and conductivity, and more particularly relates to a stretched conductive sealing material that has both sealing properties and conductivity. This invention relates to a conductive sealing material that is used as a sealing material and a conductive treatment material for connecting parts between metal pipes, pull boxes, joint boxes, etc.

Conventionally, metal tubes for storing electric wires were connected to each other by applying a sealant mainly composed of Komyotan, Kintan, Suzutan, etc. onto the threaded part of the outer circumferential surface of the terminal end of each metal tube, or After winding an insulating sealing tape as described in the above publication and butting the ends of each metal pipe against each other, a metal cylindrical coupling with a threaded inner circumferential surface is fitted with iron, and then the sealing agent or insulating material is applied. This was done by passing copper wires over metal tubes that were insulated with seal tape, and fixing the copper wires with metal bands to perform conductive treatment.

However, the work of attaching copper wires and metal bands in the above-mentioned conductive treatment method is extremely troublesome and requires a lot of manpower and time. This difficulty will be further compounded.

The present invention relates to a conductive sealing material that solves all the drawbacks of the conventional conductive treatment methods described above, and the present invention relates to a film made of a mixture of unfired polytetrafluoroethylene (PTFE) and a conductive substance. It is a stretched molded product with a surface resistance of 1×1 ohm or less and a specific gravity of 0.5 to 2.7.

In the present invention, the surface resistance of the conductive sealing material is 1×1.
If it is more than 100 ohms, it is not preferable because the effect of conductive treatment when used for conductive treatment of various connection parts is small.

Furthermore, if the specific gravity is less than 0.5, the effect of the conductive treatment will be small as mentioned above, and if you try to obtain one with a specific gravity of 2.7 or more, you will have to mix a large amount of conductive substance, which will affect the moldability during manufacturing. Either method is undesirable because it becomes extremely bad and it is virtually impossible to obtain the desired conductive sealing material.

In the present invention, the conductive material mixed with unsintered PTFE includes carbon, graphite, steel, iron, silver,
One or more metals such as lead, zinc, tin, aluminum, alloys, metal oxides, etc. are used.

These conductive substances are often used in the form of powder, but they can also be used in the form of chips, fibers, etc. In addition, in the present invention, the conductive material has a surface area of about 2
It is particularly preferable to use a powder having a particle size of 0 to 500 m/m, since it is possible to obtain a conductive sealing material with a particularly excellent conductive treatment effect, and also to have good moldability during production. The particle diameter of the conductive substance having a surface area within the above range varies somewhat depending on the type of the conductive substance, but is usually about 0.01 to 150.
It is on the order of microns. When obtaining the conductive sealing material of the present invention, the amount of the conductive substance mixed with unfired PTFE is as follows:
Although it varies depending on the specific gravity, shape, surface area, etc. of the conductive material, it is usually about 2 to 75 parts by weight based on the weight of unsintered PTFEIO.

The conductive sealing material of the present invention includes, for example, PTFE powder,
Conductive substances and naphtha, liquid paraffin, xylene,
A liquid lubricant such as toluene is mixed in a predetermined ratio, this mixture is compressed and preformed, and then extruded, rolled, etc., and formed into a predetermined shape such as a film, tube, or rod. PTFE is removed and then stretched in at least one direction at a temperature below the melting point of PTFE.

At the time of stretching, care must be taken to ensure that the specific gravity does not fall below 0.5 depending on the stretching ratio.

If the specific gravity is less than 0.5, the surface resistance of the resulting conductive sealing material will increase, which is not preferable. Note that the stretching ratio in this case varies depending on the specific gravity before stretching, the stretching direction, etc., but is usually about 10 to 300%. In addition,
In the conductive sealing material of the present invention, various additives such as pigments for coloring, abrasion resistance improvement,
Asbestos powder, glass powder, etc. can also be mixed in to prevent low-temperature flow.

The conductive sealing material of the present invention is used by being rolled onto a predetermined portion while being stretched by applying a tensile force, and when wound in this manner, the sealing materials adhere to each other due to the self-adhesive property of unsintered PTFE. It is something.

Since this sealing material is stretched, it has a high mechanical strength, and has the advantage that it is not accidentally cut due to tensile force during use, and is excellent in workability. Furthermore, the surface of the sealing material becomes rough due to the stretching, and when it is wound, it does not slip, resulting in good workability and good adhesion between the sealing materials. Furthermore, in the present invention, after the above-mentioned stretching, the stretched state is maintained, in other words, the length in the stretching direction is regulated and heat treated to fix the stretched state,
A conductive sealing material with high mechanical strength and excellent dimensional stability can be obtained.

This heat treatment is performed at a temperature above the working temperature of the sealing material and at a temperature above the PT.
It is carried out at a temperature below the melting point of FE. Further, the conductive sealing material of the present invention can be used with a conductive adhesive layer provided on at least one side thereof, if desired.

In this case, the conductive adhesive layer can be provided on one or both surfaces of the sealing material, or on a portion thereof. Since the conductive sealing material of the present invention has both sealing properties and conductivity, it is possible to perform sealing and conductive treatment on various connection parts that require conductive treatment by simply wrapping or wrapping them. The manpower and time required for construction can be greatly reduced.

In addition, since it is stretched, it has high mechanical strength and will not break due to stretching during use, allowing for reliable sealing work. Furthermore, it has characteristics such as excellent weather resistance, chemical resistance, and heat resistance, can sufficiently exhibit its functions for a long period of time, and is easy to manufacture. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but these are not intended to limit the present invention.

In addition, all "parts" in the examples indicate "parts by weight." Example 1 10 pieces of PTFE powder (trade name: Teflon 6J, manufactured by Mitsui Fluorochemical Co., Ltd.) were uniformly mixed with 5 parts of carbon powder with a surface area of 105 cm and an average particle size of 0.03 microns by a wet blending method. Furthermore, liquid lubricant liquid paraffin is mixed uniformly in three parts, and this mixture is heated to a pressure of 20 kg.
/ After compression preforming, this is extruded to a diameter of 1
It is made into a round bar shape and then rolled into metal.

A film-like product of 0.1 willow with a thickness of 0.1 is obtained. /Then, this film-like material is soaked in trichloroethylene for 5 minutes to remove the liquid lubricant.

Tensile strength of film with liquid lubricant removed UIS-K
-6885) is 115k9/ground in the long direction,
The width direction was 3.2k9/m, and the specific gravity was 1.46. Thereafter, this film was stretched in the length direction and/or width direction (stretching temperature: 2500), and the specific gravity was varied to obtain conductive sealing materials of sample numbers 1 to 3.

Table 1 shows the results obtained by measuring the tensile strength of these sealing materials in the stretching direction.

In addition, the surface resistance was measured using a resistance meter (Digital MIN manufactured by Takeda Riken).
I-MULTIMETER), and the results shown in Table 1 were obtained. In addition, when measuring, the sample piece has a width of 1
3 skin, length 100 side, distance between electrodes is 5
It was set as 0 skin. *Next, in order to confirm the sealing performance when these conductive sealing materials are used for connections that require conductive treatment, the above sealing materials (width 13 side ) is wrapped in one half-wrap layer, and a steel plug socket is further tightened over the sealing material, and a gas inlet is provided in one of the plug sockets.
Nitrogen gas was injected through the inlet at a pressure of 5k9/m, and the presence or absence of gas leakage was confirmed using a gas leak detector. The results are also shown.

Furthermore, in order to confirm the conductive treatment effect of the conductive sealing material, the results of measuring the resistance between the sockets are shown.

For comparison, data for sealing materials (sample numbers 4 to 6) obtained by stretching the above-mentioned long film-like material so that its specific gravity becomes 0.5 or less are also shown.

Table 1 In the above Table 1, the "0" mark indicates that the film was stretched in the direction indicated in the column, and the "1" mark indicates that the film was not stretched.

Example 2 Same PTFE powder 100 as used in Example 1
Copper powder with a surface area of 38 m/m and a particle size of 43 mounds
The anchor portion and the liquid lubricant naphtha No. 1 No. 2 anchor portion were mixed uniformly, and this mixture was pressed into a mold in the same manner as in Example 1, and then heated at 120°C.
Heat for 3 minutes to remove the liquid lubricant and obtain a long round rod with a diameter of 4 skins (specific gravity: 2.66).

Next, this round bar-shaped object was stretched in the length direction at a stretching ratio of 50% to obtain a long round rod-shaped conductive sealing material. This conductive sealing material has a specific gravity of 2.42, a tensile strength in all directions of up to 170 kg/c, a surface resistance of 3.0xl ohm, and a resistance between flanges of 1.5 ohm, and may cause gas leakage. There wasn't.

In addition, when confirming the sealing property and the conductive treatment effect, the sealing material was assembled as a gasket into a steel flange having a diameter of 5 mm, and measurements were taken. As is clear from the above Examples and Comparative Examples, the conductive sealing material of the present invention:
It has low surface resistance and high mechanical strength, and when used in connections that require conductive treatment, it can exhibit excellent sealing properties and conductive treatment effects, and it is resistant to stretching during use. The force should be applied to avoid any inconvenience such as breakage.

Claims (1)

[Scope of Claims] 1. A stretched molded product such as a film made of a mixture of unfired polytetrafluoroethylene and a conductive substance, with a surface resistance of 1×10^6 ohm or less and a specific gravity. Conductive sealing material with a value of 0.5 to 2.7. 2. The conductive sealing material according to claim 1, which is provided with a conductive adhesive layer on at least one side.