JPH11222530A - Production of fluororesin-coated metallic wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing a metallic wire having a fluororesin coating having excellent adhesiveness by subjecting the fluororesin coating to atmospheric plasma treatment uniformly at good efficiency without fail. SOLUTION: There is provided a process for producing a fluororesin-coated metallic wire having good adhesiveness, which process comprises; helically winding a first electrode 2a around the external surface of a tubular dielectric 1; introducing an atmospheric inert gas into the cavity of the dielectric; decreasing the oxygen concentration of the atmosphere to 500 ppm or below; leading a fluororesin-coated metallic wire 3 into the cavity of the dielectric; adopting the core wire 4 of the fluororesin-coated metallic wire 3 as a second electrode; generating a glow discharge plasma at atmospheric pressure; and subjecting the external surface of the wire 3 to plasma treatment to improve its adhesiveness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a metal wire having a fluororesin coating having excellent adhesiveness.

[0002]

2. Description of the Related Art Fluororesins are used in various fields because of their excellent heat resistance, chemical resistance, electrical insulation, and the like. Metal wires coated with fluororesins (hereinafter, metal rods are included) Is also used in various fields due to such properties of the coated fluororesin. But,
On the other hand, since the fluororesin is non-adhesive, when another material is laminated on the outer surface of the fluororesin-coated metal wire, the fluororesin layer on the outer surface is usually subjected to a surface treatment in advance. ing. Various methods are known for such surface treatment, but all have problems.

[0003] For example, Japanese Patent Laid-Open No. 5-106053 discloses that a low-pressure glow plasma is generated inside a tubular body.
A method for treating the inner surface of a tubular body is described. Similarly, Japanese Patent Application Laid-Open No. 5-202481 describes a method for treating the inner surface of a tubular body by generating glow plasma inside the tubular body under atmospheric pressure. Although methods are described, none of them can treat the outer surface of the tubular body.

Therefore, Japanese Patent Application Laid-Open No. 6-226810 describes a method in which the outer surface of a fluororesin tubular body is subjected to a plasma treatment under atmospheric pressure to enhance its adhesiveness.
In this method, the electrodes in the plasma processing apparatus appear to be plate-shaped, and therefore, the distance between the electrodes and the tubular body is not constant, and it is difficult to uniformly treat the outer surface of the tubular body.

In particular, in the case of a metal wire coated with a fluororesin, a fluororesin layer on the outer surface of the metal wire having a fluororesin coating with improved adhesion is efficiently and reliably and uniformly treated by a plasma treatment. The production method is not known.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and in particular, it has been proposed to efficiently and surely and uniformly form a fluororesin layer on the outer surface of a fluororesin-coated metal wire. An object of the present invention is to provide a method for producing a metal wire having a fluororesin coating excellent in adhesiveness by plasma treatment.

[0007]

According to the method of the present invention for producing a fluororesin-coated metal wire having excellent adhesiveness, a first electrode is spirally wound around the outer surface of a tubular dielectric, and the tubular electrode is laid. An inert gas at atmospheric pressure is introduced into the body, the oxygen concentration in the atmosphere is adjusted to 500 ppm or less, and a fluororesin-coated metal wire is guided inside the tubular dielectric. 2 electrodes,
A glow discharge plasma is generated under atmospheric pressure, and the outer surface of the fluororesin-coated metal wire is treated with a plasma to enhance the adhesiveness.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the method according to the present invention, for example, a tubular body made of plastic, glass, or the like is used as the tubular dielectric, and as shown in FIG. The first electrode 2a is spirally wound around the surface and laid. As the first electrode, a foil or metal wire made of copper, aluminum, stainless steel or the like is used. As will be described later, the second electrode 2b is the core wire 4 of the fluororesin-coated metal wire 3 which is subjected to atmospheric pressure plasma treatment inside such a tubular dielectric.

One of the first and second electrodes is a high-voltage electrode, and the other electrode is a ground electrode.
Either may be a high-voltage electrode or any may be a ground electrode. The high-voltage electrode is usually connected to an AC power supply 5 in a commercial frequency range of 50 Hz to 10 kHz.

When the frequency of the power supply is lower than 50 Hz,
It is difficult to maintain the discharge, and when the frequency exceeds 10 kHz, the heat generation becomes remarkable, and the transition to the local discharge is apt to occur. Becomes On the other hand, the high frequency voltage is preferably in the range of 1 kV to 15 kV. When the high frequency voltage is lower than 1 kV, no plasma discharge is obtained,
On the other hand, when it is higher than 15 kV, it is easy to shift to arc discharge, and the discharge cannot be controlled.

In the present invention, the pitch p of the first electrode 2a is not particularly limited, but as shown in FIG. During this process, a weak discharge portion 7 is formed in the coated fluororesin layer 6, and the discharge portion 8 other than the weak discharge portion obtains an improvement in surface activity and a cleaning effect, and an effect of increasing a chemical reaction in the weak discharge portion. Usually 5 to 2
A range of 0 mm is preferred.

Further, in the present invention, the distance L between the electrodes, that is, the first electrode 2a on the outer surface of the tubular dielectric 1 and the second electrode 2b composed of the core wire 4 of the fluororesin-coated metal wire 3 are formed. The distance between them is usually in the range of about 1 to 10 mm in consideration of the strength of the plasma treatment on the fluororesin coating. Therefore, according to the present invention, by appropriately selecting the tube diameter of the tubular dielectric according to the diameter of the core wire of the fluororesin-coated metal wire, the first electrode and the core wire of the fluororesin-coated metal wire can be separated. During this time, the coated fluororesin layer of the metal wire can be efficiently subjected to atmospheric pressure plasma treatment.

In the method according to the present invention, the interior of the tubular dielectric is placed in an atmosphere of an inert gas at atmospheric pressure, and the oxygen concentration is adjusted to 500 ppm or less, preferably 300 ppm or less, particularly preferably 100 ppm or less. Plumbers are generated, and the fluororesin layer covering the metal wires is subjected to plumbum treatment to increase the adhesiveness. When the oxygen concentration is higher than 500 ppm, adhesion cannot be imparted to the coated fluororesin even by performing the plasma treatment.

In the present invention, a gas such as nitrogen, carbon dioxide, helium, or argon is used as the inert gas. Nitrogen gas is the most advantageous in view of the processing effect and economy. Further, a hydrocarbon gas, an alcohol gas, or a polymerizable monomer gas may be added to the inert gas. Examples of the hydrocarbon gas include toluene, and examples of the alcohol gas include methanol gas.
It is not limited to these. As described above, when a hydrocarbon gas or an alcohol gas is added to the inert gas, the fluorine component on the treated surface of the fluororesin tubular body or the rod-shaped body is reduced, and the organic groups derived from the hydrocarbon or the alcohol are increased. Is further improved.

According to the present invention, the fluororesin coated on the metal body is not particularly limited, but specific examples include, for example, polytetrafluoroethylene (PTF).
E), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PF
A), tetrafluoroethylene-ethylene copolymer (E
TFE), polychlorotrifluoroethylene (PCTF
E), chlorotrifluoroethylene-ethylene copolymer (ECTFE), polyvinylidene fluoride (PVDF),
Examples thereof include polyvinyl fluoride (PVF) and a tetrafluoroethylene-vinylidene fluoride copolymer.
Usually, a molten fluororesin that can be extrusion coated is preferred.

According to the present invention, not only can the fluororesin-coated metal wire be processed in a batch manner, but also by running it in a tubular dielectric, it can be processed continuously.

[0017]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited by these examples.

[0018] Length 300mm, outer diameter 20mm, wall thickness 1m
5m width on the outer surface of the central part of the glass tube
An aluminum foil having a thickness of 0.05 mm and a length of 400 mm was spirally wound at a pitch of 7 mm to form a high-voltage electrode. Separately, a PFA tape having a width of 15 mm is spirally wound around a copper wire having an outer diameter of 10 mm so as to wrap it by 1 to 2 mm to form a PFA-coated copper wire. The core of the wire was used as a ground electrode.

When nitrogen gas was introduced into the glass tube at a rate of 1 L / min from a nitrogen gas inlet provided at one end of the glass tube, the oxygen concentration in the glass tube after 10 minutes was 50 pp.
m.

Then, while running the PFA-coated copper wire in the glass tube at a speed of 1 m / min, a high-frequency AC power source having a frequency of 5 kHz and a voltage of 6 kV was applied to the high-voltage electrode.
The outer surface of the PFA-coated copper wire, that is, the PFA resin layer was subjected to an atmospheric pressure plasma treatment. PFA treated in this way
The PFA tape wound around the coated copper wire was rewound to obtain a tape-shaped sample, and the adhesion of the treated surface was measured.

That is, an epoxy resin adhesive (Bond E set manufactured by Konishi Co., Ltd.) was applied to the surface of a stainless steel plate, and the treated surface of the tape-shaped sample was stuck thereon.
The composition was cured by heating at 0 ° C. for 2 hours. Remove 1 mm on both sides of the tape-shaped sample from which the adhesive has protruded, and use a universal tensile tester with a sample width of 8 mm to remove 180 ° peel force (tensile speed: 20 mm).
0 mm / min). Table 1 shows the results.

Example 2 A PFA resin for coating a copper wire in the same manner as in Example 1 except that toluene gas was added at a rate of 0.5 L / min as a hydrocarbon gas together with nitrogen gas. The layers were subjected to atmospheric pressure plasma treatment. With respect to the fluororesin tape thus obtained, the adhesive strength of the treated surface was measured in the same manner as in Example 1. Table 1 shows the results.

Example 3 This PTFE resin layer was subjected to an atmospheric pressure plasma treatment in the same manner as in Example 1 except that a PTFE tape was wound around a copper wire. About the fluororesin tape obtained in this way,
The adhesive strength of the treated surface was measured in the same manner as in Example 1.
Table 1 shows the results.

Example 4 This FEP resin layer was subjected to an atmospheric pressure plasma treatment in the same manner as in Example 1 except that an FEP tape was wound around a copper rod. With respect to the fluororesin tape thus obtained, the adhesive strength of the treated surface was measured in the same manner as in Example 1. Table 1 shows the results.

Comparative Examples 1 to 3 The same procedure as in Example 1 was repeated except that air was introduced into the glass tube instead of the inert gas, and PFA, PTFE, or FEP tape was wound around the copper wire. Was subjected to an atmospheric pressure plasma treatment. With respect to each of the fluororesin tapes thus obtained, the adhesive strength of the treated surface was measured in the same manner as in Example 1. Table 1 shows the results.

[0026]

[Table 1]

Example 4 A copper wire having an outer diameter of 1.4 mm and the outer surface of which was coated with 0.4 mm thick PFA was subjected to atmospheric pressure plasma treatment in the same manner as in Example 2. The fluororesin-coated copper wire treated in this way was
The pieces were cut to a length of 0 cm, bound together, and impregnated with a coil varnish. This was subjected to a thermal shock test, and no change was observed in the fluororesin-coated copper wire.

Comparative Example 4 A copper wire coated with PFA was treated in the same manner as in Example 4 except that the atmosphere for the atmospheric pressure plasma treatment was air. Coated copper wire treated in this way is 20 cm
The pieces were cut into lengths, bound together, and impregnated with a coil varnish. When this was subjected to a thermal shock test, it was observed that varnish was peeled off from the fluororesin-coated copper wire.

[0029]

As described above, according to the method of the present invention, the first electrode is spirally wound around the outer surface of the tubular dielectric and laid, and the inert gas at atmospheric pressure is placed inside the tubular dielectric. At the same time, the oxygen concentration in the atmosphere was set to 500 ppm or less, a fluororesin-coated metal wire was guided inside the tubular dielectric, and a core wire of the fluororesin-coated metal wire was used as a second electrode, and glow discharge was performed under atmospheric pressure. Generate prabuma,
The outer surface of the fluororesin-coated metal wire is treated with prabuma,
The adhesiveness is enhanced to obtain a metal wire having a fluororesin coating excellent in adhesiveness.

Therefore, according to the method of the present invention, it is possible to efficiently and reliably increase the adhesiveness of the fluororesin coating of the metal wire, and to obtain a fluororesin-coated metal wire having excellent adhesiveness. Furthermore, according to the present invention, since the tubular dielectric is used, even under atmospheric pressure, the discharge does not involve sparks such as corona discharge and is glow-shaped, so that the fluorine resin coating can be efficiently treated. Thus, a fluororesin-coated metal wire having high productivity and excellent adhesiveness can be obtained.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing a main part of a manufacturing method according to the present invention.

FIG. 2 is a schematic view showing a plasma treatment of a fluororesin-coated metal wire in the manufacturing method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Tubular dielectric, 2a ... 1st electrode, 2b ... 2nd electrode, 3 ... Fluororesin coated metal wire, 4 ... Fluororesin coated metal wire core wire, 5 ... Power supply, 6 ... Fluororesin coated metal wire Coated fluororesin layer.

Claims (3)

[Claims] A first electrode is spirally wound around the outer surface of a tubular dielectric and laid. An inert gas at atmospheric pressure is introduced into the tubular dielectric, and the oxygen concentration of the atmosphere is reduced to 50%.
0 ppm or less, a fluororesin-coated metal wire is guided inside the tubular dielectric, a core wire of the fluororesin-coated metal wire is used as a second electrode, and a glow discharge plasma is generated under atmospheric pressure to produce the fluororesin. A method for producing a fluororesin-coated metal wire having excellent adhesiveness, comprising subjecting an outer surface of the coated metal wire to a plasma treatment. 2. The method according to claim 1, wherein the fluororesin is a polytetrafluoroethylene, a tetrafluoroethylene-hexafluoropropylene copolymer or a tetrafluoroethylene-perfluoroalkylvinyl ether copolymer. 3. The method according to claim 1, wherein the inert gas is nitrogen gas.