JPH059313A - Method for sealing holes of fluororesin film - Google Patents

Abstract

PURPOSE:To impart high sealability to a fluororesin film and enable the film to be used as a sealing material even under severe conditions. CONSTITUTION:A tetrafluoroethylene film 13 is irradiated with high speed oxygen atoms 11 generated from an atomic oxygen generator I to seal the small holes of the film 13 by the oxidative reaction of the atomic oxygen 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluororesin film sealing method for making a fluororesin film a sealing material suitable for use under severe conditions.

[0002]

2. Description of the Related Art A film made of PTFE (polytetrafluoroethylene), which is a fluororesin, has excellent properties such as chemical resistance, heat resistance (continuous use at 260 ° C.), water repellency, and insulation properties, and is therefore widely used. Is used in a variety of ways. On the other hand, although the above-mentioned PTFE is a thermoplastic resin having a melting point of 327 ° C., it has a high melt viscosity of 10 ¹¹ to 10 ¹² poises, so that when it is made into a film, it cannot be melt-extruded, which is a conventional method for producing a film. Therefore, a manufacturing method is adopted in which a fine powder of PTFE is compressed once, heated to a temperature equal to or higher than the melting point to form a molded product in which PTFE particles are fused, and further cut into a film. ..

[0003]

However, in the case of the PTFE film produced by the above production method, it is extremely advantageous if it can be used as a sealing material under severe conditions because of the above-mentioned excellent characteristics. PTFE
Problems such as weak cohesive strength between the fine particles, and voids between the fine particles that cause small holes (voids) as shown in the photograph of FIG. 4 taken at a magnification of 5000 times when processed into a film. In particular, although it can be used as a gas permeable film due to the small pores described in the above item, on the other hand, it is not suitable for use as a sealing material because of its poor airtightness.

Therefore, the present invention intends to provide a method of sealing a fluororesin film, which enhances the airtightness of the above-mentioned PTFE film and makes a sealing material suitable for use under severe conditions. It is what

[0005]

In order to solve the above-mentioned problems, the present invention irradiates a film made of polytetrafluoroethylene with atomic oxygen at a flow rate of 10 Km / sec or less to atomize the small holes in the film. A method for sealing a fluororesin film is characterized in that the pores are sealed by an oxidation reaction with oxygen.

[0006]

[Function] A film made of polytetrafluoroethylene,
When atomic oxygen is irradiated at a flow rate of 10 Km / sec or less, the small holes in the film are blocked by the oxidation reaction by atomic oxygen.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of an atomic oxygen generator I used for carrying out the method for sealing a fluororesin film according to the present invention, which is evacuated by an exhaust device 1 comprising an oil rotary pump, a mechanical booster pump or the like. An arc jet 4 adapted to be driven by a DC constant current power source 3 is installed in the vacuum chamber 2 thus configured, and an argon gas cylinder 7 is attached to the arc jet 4 via a gas controller 5 and an opening / closing valve 6. The oxygen cylinder 10 is connected through the gas controller 8 and the on-off valve 9, and the direct current arc is discharged by the direct current constant power source 3 using the argon gas from the argon gas cylinder 7 as a carrier gas. In the argon plasma generated by the discharge,
By adding oxygen from the oxygen cylinder 10 at a flow rate of about 3 to 5% with respect to the flow rate of the carrier gas, the oxygen is dissociated so that atomic oxygen 11 in a clean state can be generated from the arc jet 4. , And the atomic oxygen 1
1 is irradiated toward the PTFE film 13 set on the sample holder 12 in the vacuum chamber 2. In FIG. 1, 14 is a heat sink for cooling exhaust gas, and 15 is a vacuum gauge.

When the fluorine resin film is modified using the atomic oxygen generator I so as to have a function as a sealing material, the PTFE film 13 is held in the sample holder 12 in the vacuum chamber 2, and While evacuating the inside of the vacuum chamber 2 by the exhaust device 1, the beam of atomic oxygen 11 generated from the arc jet 4 is irradiated on the surface of the PTFE film 13 at a flow rate of 10 km / sec or less for a required time. PTF as needed
By cooling the back surface of the E-made film 13,
The small holes of the FE film 13 are sealed.

As an example, the flow rate of argon gas is 2 l / mi.
n, oxygen flow rate 62 cc / min, arc jet discharge voltage 20 V, arc jet discharge current 45 A, atmospheric pressure (vacuum degree) 0.06 Torr, film cooling water -2
The rate of collision of atomic oxygen 11 with the PTFE film 13 was 1 km / sec at the position of the sample holder 12 40 cm downstream of the arc jet 4 at 0.5 l / min at 0 ° C.
When it was carried out for 30 minutes under the conditions of the above, due to the interaction between the oxidation reaction by atomic oxygen 11 and the collision of argon ions and electrons in the argon plasma, as shown in the photograph of FIG. Film 13
The small holes in the above state were sealed, and when the operation was continued for another 30 minutes from such a state, the small holes were completely disappeared as shown in the photograph of FIG. 3 taken at a magnification of 5000 times. Therefore, the airtightness of the PTFE film 13 could be achieved. In the above, the irradiation rate of atomic oxygen 11 on the PTFE film 13 was 10 km / sec.
Although it is described below, this is because if the flow rate of the atomic oxygen 11 blown out from the arc jet 4 reaches the surface of the PTFE film 13, the small holes of the PTFE film 13 can be sealed by an oxidation reaction. 10 km / sec
In the above, the small holes are expanded to the contrary, and even if they are oxidized at all, even the oxidized places are scraped and taken.

In the present invention, as described above, the material has physical properties such that small holes are formed in the manufacturing process and it has gas permeability, so that it has excellent properties such as heat resistance (-268 to 260 ° C.). Film made of PTFE that does not have high airtightness
By irradiating 3 with atomic oxygen 11, a small hole can be sealed and high airtightness can be provided. Since the PTFE film 13 that has been subjected to such a sealing treatment maintains the excellent properties of PTFE such as heat resistance and chemical resistance, for example, as a sealing material under high pressure, high vacuum, high temperature atmosphere, etc., Alternatively, it can be used as a sealing material for a portion where gas tightness is required and airtightness is required.

The present invention is not limited to the above embodiment, and the atomic oxygen generator I is not only the one shown in FIG. 1 but also a device utilizing a microwave discharge system and a high frequency discharge (RF). It is needless to say that a device utilizing the system may be adopted, and various changes may be made without departing from the scope of the present invention.

[0013]

As described above, according to the sealing treatment method for a fluororesin film of the present invention, a polytetrafluoroethylene film having small pores originally has an atomic oxygen content of 10 Km / sec or less. By irradiating at a high speed, the small holes are sealed by the oxidation reaction of atomic oxygen, so that the airtightness can be added while maintaining the physical properties of the film, and therefore the film after the treatment can be added. It has an excellent effect that it can be used as a sealing material under severe conditions.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of an atomic oxygen generator used for carrying out a method for sealing a fluororesin film according to the present invention.

FIG. 2 is a photograph showing the grain structure of a film after being irradiated with atomic oxygen for 30 minutes by the sealing treatment method of the present invention.

FIG. 3 is a photograph showing the grain structure of a film after being irradiated with atomic oxygen for 60 minutes by the sealing treatment method of the present invention.

FIG. 4 is a photograph showing the fiber structure of PTFE.

[Explanation of symbols]

 I Atomic oxygen generator 2 Vacuum chamber 4 Arc jet 10 Oxygen cylinder 11 Atomic oxygen 13 PTFE film

Claims (1)

Claims: 1. A film made of polytetrafluoroethylene is irradiated with atomic oxygen at a flow rate of 10 Km / sec or less, and the small holes in the film are sealed by an oxidation reaction by atomic oxygen. A method for sealing a fluororesin film, which is characterized.