JPH0917551A - Corona discharge treating method - Google Patents

Abstract

PURPOSE: To prevent breakage of an insulator caused by temperature rise due to corona discharge and easily adjust the shape of an electrode by using a tubular conductive member serving as an external electrode and making coolant flow in the tube. CONSTITUTION: An external electrode 1 is formed in such a way that in order to uniformly treating the whole resin surface, a straight stainless steel pipe 3 which acts as an conductor of the external electrode 1 is covered with an insulator 2 made of silicone rubber having flexibility, and adjusted in a coil shape so as to fit to the shape of a resin hose for an inner tube for conducting corona discharge. A conductor of a steel wire 6 is arranged in the center. Therefore, the shape of the electrode is previously adjusted in order to conduct uniform discharge.

Description

Detailed Description of the Invention

[0001]

[Industrial application] In order to obtain a product such as a laminated body or laminated pipe by adhering resin and other materials such as rubber such as electric wires and rubber hoses, the surface of the resin is continuously subjected to corona surface treatment. Regarding the method.

[0002]

2. Description of the Related Art Conventionally, for example, in the production of a laminated rubber hose having a resin layer on the inner side and an inner tube layer made of a rubber layer on the outer side, before laminating the outer rubber layer,
Corona discharge treatment is applied to the surface of the resin layer to improve the adhesiveness with the rubber layer.

At this time, a mandrel for manufacturing a hose having conductivity inside is used as an internal electrode, and one external electrode is formed by laminating or covering a part or the whole of a conductor with a hard insulator such as alumina or ceramic. Alternatively, corona discharge treatment has been performed using a laminate or coating of a flexible insulator such as a resin material or a rubber material.

[0004]

If the external electrode is not covered with an insulator, the resin layer which is the object to be processed is relatively thin, and pinholes, scratches, foreign substances, film thickness deviations, etc. may occur in the resin layer. In some cases, a local electric spark is generated, uniform treatment cannot be performed, and the resin of the object to be treated may be damaged by the spark. For this reason, it is preferable to cover the external electrodes with an insulator for stable treatment, but as described above, the conductors used for the external electrodes are laminated or covered with an insulator having flexibility. When the resin is used, the insulator has followability even when it is desired to change the shape of the conductor. Therefore, after laminating or coating, the shape of the insulator is straight, coiled, etc. However, there is a case that the heat resistance, high voltage resistance (dielectric breakdown characteristics), ozone resistance, etc. of the insulator are poor, but at this time, heat generated by discharge or ozone This has the drawback of causing early destruction of the insulator due to the occurrence of

On the other hand, when a conductor laminated or covered with a hard insulator such as alumina or ceramic is used, it is possible to prevent destruction caused by heat generation due to discharge or generation of ozone, while a circular shape such as a hose is used. In this case, the conductor cannot be adjusted to a shape suitable for discharging, so that it may be difficult to perform uniform discharge processing. At this time, the hard insulator may reach a very high temperature, so that the object to be processed may be damaged by heat.

The present invention has been made in view of the above circumstances, and it is possible to adjust the shape of the external electrode so as to follow the conductor even when the insulator is laminated or covered, and the discharge is achieved. It is an object of the present invention to provide a corona discharge method capable of suppressing the destruction of the insulator caused by the heat generation due to the heat generation.

[0007]

In a laminated rubber hose having an inner tube layer made of a resin layer on the inner side and a rubber layer on the outer side of the inner tube layer, on the mandrel for producing a hose having a conductor inside, the inner oil of the hose is In the external electrode for subjecting the surface of the layer to corona discharge treatment to improve the adhesion with the outer peripheral rubber, (1) the conductor of the external electrode is laminated with an insulator having flexibility (flexibility) Alternatively, (2) the corona discharge treatment method is characterized in that the conductor of the external electrode is tubular and the cooling medium is allowed to flow in the tubular.

Regarding the mandrel for manufacturing a hose which plays the role of the internal electrode, the conductor inside the mandrel is not particularly limited as long as it has conductivity, but copper wire, stainless wire, iron wire. Conductors such as are preferably used. In this case, this internal electrode is preferably a ground electrode. Further, of the mandrel, the portion other than the conductor is preferably light and flexible in terms of handling. Specifically, synthetic resins such as silicone resins and polyurethane resins, insulators such as rubbers such as NBR, and rubbers containing carbon black and having some conductivity can be used.

The corona discharge treatment is already widely used industrially, and the conditions generally used in the present invention can be adopted. However, in order to generate corona discharge, a high frequency high voltage is applied. It is necessary that the three elements, that is, the presence of the discharge gap and the electrode covered with at least one insulating layer, be satisfied. Of these, the frequency is 10
-100 kHz is preferable. If the frequency is 10 kHz or less, the efficiency of discharge is reduced, and particularly at 10 kHz or less, it is difficult to maintain stable discharge. Also, the frequency is 100k
When the frequency exceeds Hz, the material to be processed is more likely to be damaged by heat. As voltage, 5-50k
A peak voltage of V is preferred. If it is less than this, electric discharge is hard to occur or becomes unstable, and if it is more than this, there is a risk of damaging the object to be processed such as making holes. Any voltage waveform such as a sine wave, a triangular wave, and a rectangular wave may be used.

The discharge gap is preferably 0.5 to 20 mm. If the porosity becomes narrower than this, the electrode and the object to be processed will come into contact with each other due to fluctuations in thickness of the object to be processed or vibration
Since discharge does not occur at the contact portion, effective treatment may not be possible, and if the gap is larger than this, stable discharge cannot be generated. Further, it is desirable that the width of the discharge gap, that is, the distance between the electrode and the object to be treated, is substantially constant at each position of the electrode in order to generate a uniform discharge.
It can be appropriately adjusted according to the actual shape of the electrode or the object to be treated and the treatment effect. Also, air is usually present in this void, but for the purpose of stabilizing the discharge or enhancing the treatment effect, it is replaced with a gas such as oxygen, nitrogen, or argon, or the vapor of a low-molecular compound is mixed. It can be done.

Finally, regarding the electrode coated with at least one layer of an insulator, the external electrode of the present invention comprises a conductor and a flexible insulator covering the conductor. If the resin to be treated is an insulator, corona discharge can occur even if the external electrodes are not covered with an insulator,
For the reasons described above, it is desirable that the external electrode is also covered with the insulator.

The hose member resin to be subjected to corona discharge is not particularly limited as long as it has thermoplasticity such as homopolymer, blend polymer or copolymer.

On the other hand, as the flexible (flexible) insulator laminated or coated on the conductor of the external electrode according to the present invention, a resin material such as fluororesin, fluororubber, silicone resin, silicone rubber or the like can be used. Examples thereof include rubber materials, but the material is not limited to these as long as they can follow the conductor of the external electrode when the conductor is deformed.

Further, as the conductor of the tubular external electrode, a tubular conductor such as a copper pipe, a stainless pipe, and an iron pipe is used, but the conductor is not limited to these. Further, as the cooling medium flown in the tube,
A liquid such as water, oil or liquid nitrogen, or a gas such as air capable of heat exchange is used.

[0015]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples. FIG. 1 is a schematic perspective view showing a corona discharge treatment apparatus showing the present invention. Example 1 That is, in the external electrode 1 shown in FIG. 1, in order to uniformly process the entire resin surface, the linear stainless steel pipe 3 which is a conductor of the external electrode 1 has flexibility (flexibility). After coating the silicon rubber insulator 2 that it has, it was adjusted into a coil shape in accordance with the shape of the inner tube resin hose 4 for performing corona discharge. The mandrel 5 serving as an internal electrode has a diameter of 10 mm, is made of carbon-containing EPDM rubber vulcanizate, and has a linear 1.
A 5 mm iron wire 6 provided with a conductor was used.

As the hose member resin 4 to be subjected to corona discharge, a polyamide resin having a thickness of 100 μm was extrusion-coated on the mandrel. Further, as the high frequency generator 7, "model ET type 1.5" manufactured by VETAPHON was used, the corona output was set to 910 W, and the mandrel was set at a speed of 14 m / min. And moved for discharge treatment.

Details of the external electrode of the resin for hose member to be subjected to corona discharge of the present invention, that is, a coolant is flown through the tubular conductor, and the tubular conductor is subjected to various flexibility (flexibility). ) Of the present invention laminated and covered with an insulator having a) and the conventional linear conductor alone, each material, size, type of insulator, size, type of cooling medium,
(1) Damaged state of insulator after changing to coil shape, discharge possibility, external electrode temperature, 20,000 mm, 200,000 mm An experiment was conducted on the damage condition of the. These details are as shown in Table 1 (Examples 1 to 8) and Table 2 (Comparative Examples 1 to 4).

[0018]

[Table 1]

[Table 2]

For the sake of caution, the evaluation methods for the items shown in Tables 1 and 2 are as follows. (1) First, the state of damage to the insulator was visually observed after the electrodes were adjusted to have a coil shape before discharge. (2) Next, the initial discharge state was visually observed to determine whether discharge was possible. (3) Subsequently, the state of damage of the external electrode after 20,000 mm treatment and 200,000 mm treatment was observed.

[0020]

As described in detail above, the gist of the present invention is, for example, a laminated rubber hose having an inner tube layer made of a resin layer on the inner side and a rubber layer on the outer side, and having a conductor inside. On a mandrel for manufacturing a hose, an outer electrode for performing corona discharge treatment to improve the adhesion of the inner fat layer of the hose to the outer peripheral rubber, in which the conductive member that is the outer electrode is tubular By flowing a cooling medium through the pipe, the temperature of the insulator does not rise even if a flexible insulator is used, unlike the conventional case, so that damage does not occur, and compared with the conventional case. Then, the shape of the electrode can be adjusted in advance so that the discharge can be performed uniformly.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a corona discharge treatment device showing the present invention.

[Explanation of symbols]

 1 Coiled External Electrode 2 Insulator Having Flexibility 3 Tubular External Electrode Conductor 4 Hose Member Resin 5 Mandrel 6 Conductor Inside Mandrel 7 High Frequency Generator for Corona Power Supply

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinji Saito 1-10-16 Kamisuimotocho, Kodaira-shi, Tokyo

Claims (2)

[Claims] 1. In an external electrode for continuously performing corona discharge treatment on a long resin surface, (1) a conductor of the external electrode is laminated or covered with an insulator having flexibility,
(2) A corona discharge treatment method characterized in that the conductor of the external electrode has a tubular shape, and a cooling medium is flown into the tube. 2. In a laminated rubber hose having an inner tube layer made of a resin layer on the inner side and a rubber layer on the outer side, a corona discharge is applied to the surface of the inner oil layer of the hose on a hose manufacturing mandrel having a conductor inside. In the external electrode for performing the treatment, (1) the conductor of the external electrode is laminated or covered with an insulator having flexibility, and (2) the conductor of the external electrode has a tubular shape, The corona discharge treatment method according to claim 1, wherein a cooling medium is flown in the tube.