JPH10199697A - Surface treatment device by atmospheric pressure plasma - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate need of a a vacuum condition forming device at all, achieve compactness and low cost of a whole body of a device, and generate stable glow discharge plasma to correctly and easily perform specified surface treatment regardless of the size or form of a subject to be treated. SOLUTION: A discharge generating electrode 1 connected to a high frequency power source 3, and a cylindrically formed pair electrodes 5 having a nozzle- shaped gas exist 6 at a tip are doubly disposed in and out to form a whole body of a device in a touch-like form, and inner and outer circumferential surfaces of both electrodes 1, 5 are covered in tightly stuck form with inorganic insulation 8, 9. In addition, gas including at least helium gas or hydrogen is introduced to a circular discharge space 12 formed between both electrodes under atmospheric pressure or a pressure close to the atmospheric pressure, and a high frequency voltage is applied to the discharge generating electrode 1. Abnormal discharge such as spark or arc discharge is not generated, but stable glow discharge plasma is generated in a discharge space 12, and gas including chemically active excitation seed generated by the plasma is irradiated toward the surface of a subject 13 to be treated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of applying a coating or coating to a resin such as polyethylene, polypropylene, or PTFE (polytetrafluoroethylene) to make the surface water-repellent hydrophilic. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment apparatus using atmospheric pressure plasma, which is used when performing surface treatment such as reforming or cleaning organic substances attached to the surface of glass, ceramics, metal, semiconductor, and the like.

[0002]

2. Description of the Related Art As a surface treatment apparatus of this type, generally known in the prior art, as shown in FIG. 2, a vacuum vessel (bell jar) 21 to which an exhaust system 20 is connected is located at a vertical position. Discharge generating electrode 24 via insulators 22 and 23
And the counter electrode 25 are placed in opposition to each other, and the exhaust system 20 is operated to evacuate the vacuum vessel 21 to introduce a discharge gas containing at least oxygen into the vacuum space.
A low-pressure glow discharge plasma is generated by applying a high-frequency voltage to the discharge generating electrode 24 from the high-frequency power supply 26 through the matching unit 27, and the vacuum vessel 21 is generated by a gas containing a chemically active excited species generated by the plasma.
To be processed (substrate) 2 installed and held on counter electrode 25 inside
8 surface.

[0003]

However, the conventional general surface treatment apparatus using a low-pressure glow discharge plasma having the above-described structure requires a vacuum vessel 21 and a vacuum condition forming apparatus such as an exhaust system. Because the whole is large and its installation is fixed, it is difficult to use large-area workpieces or surface-treated workpieces with severe irregularities due to equipment capacity and space. However, there is a problem that not only is there a limit naturally, but also the equipment cost becomes high.

Further, in order to simplify such an apparatus for forming vacuum conditions, for example, as disclosed in Japanese Patent Publication No. 6-72308, a discharge generating electrode disposed at a vertical position in a reaction vessel is used. A solid dielectric is coated on each surface of the counter electrode, a rare gas and a monomer gas are introduced into the reaction vessel, and the substrate surface is treated by plasma excitation at atmospheric pressure. Although a surface treatment apparatus using atmospheric pressure plasma has been proposed, such a surface treatment apparatus using atmospheric pressure plasma does not require an exhaust system as a vacuum condition forming apparatus, but uses a bell jar instead of a vacuum vessel. In addition, since the object to be processed (substrate) is installed in the bell jar, the size of the entire apparatus and the size and form of the object to be surface treated can be controlled. Is is that the problem has not been any resolution.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and can reduce the size and cost of the entire apparatus by eliminating the need for a vacuum condition forming apparatus at all. An object of the present invention is to provide a surface treatment apparatus using atmospheric pressure plasma that can easily and efficiently perform a predetermined surface treatment regardless of the size and form of an object to be treated by generating plasma.

[0006]

In order to achieve the above object, a surface treatment apparatus using atmospheric pressure plasma according to the present invention applies a high frequency voltage to a discharge generating electrode, a counter electrode, and the discharge generating electrode. A high-frequency power supply for introducing and passing a gas containing at least helium or hydrogen into a discharge space formed between the discharge generating electrode and the counter electrode under atmospheric pressure or near atmospheric pressure, and A glow discharge plasma is generated in a discharge space between the electrodes by applying a high-frequency voltage from a power source to a discharge generation electrode, and a gas containing a chemically active excited species generated by the plasma is generated on the surface of the workpiece. A surface treatment apparatus by atmospheric pressure plasma configured to irradiate the counter electrode surrounding the discharge generating electrode, and at the tip thereof While being formed in a cylindrical shape having a chiral outlet, the outer peripheral surface of the discharge generating electrode and the inner peripheral surface of the cylindrical counter electrode are tightly covered with an inorganic insulator such as glass or ceramic. It is a feature.

According to the present invention having the above structure, only the discharge generating electrode and the counter electrode are of a torch shape having a concentric inner / outer double structure, and the inner and outer peripheral surfaces of the two electrodes facing each other are formed of an inorganic insulator. A gas containing at least helium or hydrogen is introduced at atmospheric pressure or near atmospheric pressure, and a high-frequency voltage is applied to the discharge generating electrode. By applying the voltage, a stable glow discharge plasma is generated even at atmospheric pressure without generating a loss associated with the occurrence of abnormal discharge such as spark or arc discharge both inside and outside, and chemically active plasma generated by this plasma is generated. It is possible to efficiently treat the surface of the object by irradiating a gas flow containing ions and excited species to the object disposed at an external position remote from the nozzle-shaped outlet. In addition, since the entire device is small and lightweight and has a torch shape that can be easily moved without using any vacuum condition forming device or surrounding cover body, it can be used for large workpieces and surfaces that are difficult to move. Even if the object to be processed is irregularly shaped and has severe irregularities, the predetermined surface treatment can be easily and appropriately performed by the movement of the surface treatment device.

In the surface treatment apparatus using the atmospheric pressure plasma which operates as described above, when the discharge generating electrode is provided with a cooling means, the surface is continuously provided for a long time. When performing the treatment, it is possible to efficiently perform a predetermined surface treatment by preventing overheating of the discharge generating electrode, and as described in claim 3, the high-frequency power supply and the discharge generating electrode In the case where the matching device is integrally incorporated in between, the applicability when the surface treatment device is mounted on a robot and used is very excellent.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a main part of a surface treatment apparatus using atmospheric pressure plasma according to the present invention. In FIG. 1, reference numeral 1 denotes an electrode for generating discharge, which is connected to a high-frequency power source 3 via a matching unit 2 and , A cooling system 4 for circulating cooling water therein is connected.

Reference numeral 5 denotes a counter electrode formed concentrically around the discharge generating electrode 1 and having a bottomed cylindrical shape having a nozzle-like gas outlet 6 at its tip. The discharge electrode 1 and the counter electrode 5 are electrically isolated from each other through an insulator 7 and are grounded to ground. The inner and outer discharge generating electrodes 1 and the counter electrode 5 have a concentric inner / outer double torch shape. Present. Then, these discharge generating electrodes 1
And an inner peripheral surface of the counter electrode 5 are tightly covered with inorganic insulators 8, 9 such as glass or ceramic, respectively, and an annular discharge space formed between the inner and outer inorganic insulators 8, 9 is provided. 12 is a supply system 10 for helium gas or hydrogen and oxygen and a supply system 11 for a diluent gas such as argon.
Are connected to each other.

The matching device 2 is integrated with the discharge generating electrode 1 and the counter electrode 5 and is electrically connected to the high-frequency power source 3 via a flexible tube such as a coaxial cable. ing. The discharge generating electrode 1 and the counter electrode 5 are both made of a conductive metal material such as an aluminum pipe, a copper pipe, and a stainless steel pipe.

Next, the operation of the surface treatment apparatus using the atmospheric pressure plasma configured as described above will be described.
At atmospheric pressure or near atmospheric pressure, helium gas and oxygen from the supply system 10 and, if necessary, diluent gas from the supply system 11 are also transferred to the annular discharge space 12 between the discharge generating electrode 1 and the counter electrode 5. Then, the atmosphere in the discharge space 12 and the vicinity of the object 13 is replaced with an oxygen atmosphere containing helium gas. In this state, the matching device 2 is
The high frequency voltage (10 KH
z to 500 MHz), a glow discharge plasma is generated in the discharge space 12 under atmospheric pressure, and ions generated by the glow discharge plasma are generated.
By irradiating a reactive gas stream containing a chemically active excited species such as a radical from the nozzle-shaped outlet 6 toward the surface of the processing target 13, the organic substance attached to the surface of the processing target 13 is washed or modified. Perform surface treatment such as quality. In particular, when the object to be treated 13 is a resin product such as polyethylene or polypropylene, and a paint is applied or printed on the surface, chemicals such as ions and radicals generated by glow discharge plasma are used. By irradiating the surface of the resin product with a reactive gas stream containing highly active excited species, the water repellency of the surface is modified to hydrophilic, and the coating and ink adhesion and adhesion to the resin product are significantly improved. can do.

In the surface treatment apparatus operating as described above, only the discharge generating electrode 1 and the counter electrode 5 are concentrically arranged in a torch shape having an inner / outer double structure, and the two electrodes 1 and 5 are opposed to each other. The inner and outer peripheral surfaces are covered with inorganic insulators 8 and 9 so that abnormal discharges such as sparks and arc discharges occur near the inner and outer periphery even at atmospheric pressure or near atmospheric pressure. Without letting
A stable glow discharge plasma can be generated in the discharge space between the two electrodes, and the surface of the processing target 13 can be efficiently processed by the gas flow containing the excited species having high reaction activity without any loss. Is a torch-shaped compact device, and is easy to move. Therefore, even a large workpiece 13 which is difficult to move, not only a flat plate-shaped workpiece but also severe irregularities on the surface. It is possible to appropriately and easily realize a predetermined surface treatment on an object to be processed having an irregularly shaped surface.

In particular, when the cooling system 4 for circulating cooling water is connected to the discharge generating electrode 1, continuous treatment is performed by preventing overheating of the discharge generating electrode 1 when surface treatment is continuously performed for a long time. Can improve processing efficiency. Further, when the matching device 2 is integrally incorporated, it is effective when the surface treatment device is mounted on a robot and used, and the use form of the device, that is, applicability can be expanded.

[0015]

As described above, according to the present invention, a glow discharge plasma which is stable under atmospheric pressure or a pressure close to atmospheric pressure without generating a loss due to abnormal discharge such as spark or arc discharge is produced. It is possible to efficiently treat the surface by irradiating a gas flow containing a chemically active excited species generated by this plasma to a workpiece placed at a position away from the nozzle-like outlet, which can be generated. Is more expensive than conventional surface treatment equipment using low-pressure glow discharge plasma, which is expensive and requires a large-scale vacuum vessel or exhaust system for forming vacuum conditions, and a cover body that surrounds the outer periphery of the counter electrode. Is not necessary at all, and not only can the entire device be significantly reduced in size and weight and cost, and the installation space can be significantly reduced, but also the entire device can be transported in the form of a torch. Then, for an object to be processed that is too large to move, it is possible to perform surface treatment while the object to be processed is left in its place, or to an object to be processed having an irregularly shaped surface with severe irregularities. On the other hand, the size and form of the object to be treated are restricted so that the surface treatment device side can be moved along the surface shape of the object to be treated and the surface can be appropriately and easily treated. In addition, there is an effect that the applicability can be significantly expanded.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a surface treatment apparatus using atmospheric pressure plasma according to the present invention.

FIG. 2 is a cross-sectional view showing an example of a surface treatment apparatus using a low-pressure glow discharge plasma generally used in the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Discharge generation electrode 2 Matching device 3 High frequency power supply 4 Cooling system (cooling means) 5 Counter electrode 6 Nozzle gas outlet 8, 9 Inorganic insulator 12 Discharge space 13 Workpiece

Claims (3)

[Claims] 1. A discharge generating electrode, a counter electrode, and a high-frequency power source for applying a high-frequency voltage to the discharge generating electrode, wherein a gas containing at least helium or hydrogen is supplied between the discharge generating electrode and the counter electrode. Glow discharge plasma is introduced into the discharge space between the electrodes by applying a high-frequency voltage from the high-frequency power source to the discharge generation electrode while introducing and passing the same under the atmospheric pressure or a pressure close to the atmospheric pressure into the discharge space formed therebetween. A surface treatment apparatus using atmospheric pressure plasma configured to generate and irradiate the surface of the object to be treated with a gas containing a chemically active excited species generated by the plasma, comprising: Surrounding the periphery of the discharge generating electrode, and being formed in a cylindrical shape having a nozzle-shaped outlet at its tip, the outer peripheral surface of the discharge generating electrode and the cylindrical shape A surface treatment apparatus using atmospheric pressure plasma, wherein an inner peripheral surface of a counter electrode is closely covered with an inorganic insulator such as glass or ceramic. 2. The surface treatment apparatus using atmospheric pressure plasma according to claim 1, wherein said discharge generating electrode is provided with cooling means. 3. The surface treatment apparatus using atmospheric pressure plasma according to claim 1, wherein a matching device is integrally incorporated between the high-frequency power supply and the discharge generating electrode.