JP2002239376A - Surface treatment apparatus and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface treatment apparatus and a surface treatment method which can resist to dielectric breakdown even when a ferroelectric material such as titanium oxide or barium titanate is used, can realize at atmospheric pressure a composite barrier discharge generating a plasma of a high energy density, and can realize the highly efficient surface modification of a substrate. SOLUTION: In an apparatus that modifies the surface of a substrate held between the first and second electrodes provided with opposed first and second flat electrodes 22 and 23, a dielectric member 24A interposed between the electrodes 22 and 23, and a means that generates a barrier discharge by applying a high voltage between the electrodes 22 and 23 at atmospheric pressure, the member 24A comprises a first material comprising a dielectric and a second material which is lower than the dielectric in mechanical strengths and lower than it in permittivity and has an average permittivity of at least 30 along the direction of surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface modification apparatus and a surface modification method for imparting hydrophobicity to the surface of an object to be treated by a plasma discharge treatment method.

[0002]

2. Description of the Related Art Hydrophobizing technology is an important technology from the viewpoint of waterproofing and antifouling, and a method of wet coating fluorine or silicone is generally known as a hydrophobizing method.

On the other hand, a method of introducing a fluorine-containing group into a substrate surface by plasma discharge to make the substrate water-repellent is also known. For example, JP-A-9-194616, JP-A-9-24
No. 9756 discloses a method in which a ferroelectric substance such as barium titanate is inserted between metal electrodes to generate a discharge, thereby modifying the surface of a base material. Hydrophobic treatment by plasma discharge is to introduce the vaporized fluorine-containing compound into the plasma and react it on the surface of the material to be treated.
A fluorine-containing group is introduced.

[0004] While most of the water-repellent treatments by the wet method only deposit fluorine or silicon on the substrate surface,
In the plasma discharge treatment, a chemical bond is formed between the base material body and the base material surface, so that a hydrophobized product having excellent durability can be obtained. In addition, since the plasma discharge method is a dry process, it does not require a solvent, has a small load on the environment, and further imparts hydrophobicity to internal fibers even for objects having an internal structure such as cloth. It is possible.

[0005]

As described above, the hydrophobic treatment by the plasma discharge treatment is useful. However, depending on the material of the base material, a treatment time of several minutes is required to obtain sufficient hydrophobicity. However, there is a problem that productivity is lacking. That is, in order to perform the hydrophobic treatment of a large area in a short time by the plasma discharge processing method, it is necessary to increase the size of the plasma processing apparatus,
Alternatively, it is necessary to use a ferroelectric material as a dielectric material, but there is a problem that the increase in the size of the apparatus is inferior to wet processing because equipment costs and processing costs increase.

On the other hand, the use of a ferroelectric substance having a high relative dielectric constant as a dielectric material allows the substrate to be subjected to a hydrophobic treatment in a lower applied voltage and in a shorter time. It is difficult to withstand use.

[0007] For example, conventionally, a titanium oxide, a ferroelectric material such as barium titanate is used as a dielectric, a glow discharge plasma as a processing gas such as CF ₄ by discharge treatment using at atmospheric pressure non-treated Attempts have been made to impart hydrophobicity to the surface. However, since the mechanical strength is generally lower in a ferroelectric material, when only a ferroelectric material such as barium titanate is used as described above, the dielectric material is dielectrically broken down. It is difficult to endure.

The present invention solves the above-mentioned problems, and makes it difficult to cause dielectric breakdown even when a ferroelectric material such as titanium oxide or barium titanate is used and to generate a composite barrier discharge having a high energy density of generated plasma. It is an object of the present invention to provide a surface treatment apparatus and a surface treatment method that can be realized under atmospheric pressure and that achieve high efficiency of surface modification of a substrate.

[0009]

According to a first aspect of the present invention, there is provided a first and second flat plate-shaped electrodes facing each other, and a first electrode and a second electrode provided between the first and second electrodes. And a potential difference applying means for applying a potential difference between the first and second electrodes, and applying a high voltage between the first and second electrodes under atmospheric pressure. In a device for modifying the surface of the object to be processed held between the first and second electrodes by generating a barrier discharge, the dielectric member includes a first base material made of a dielectric, A surface modification comprising a second substrate having a mechanical strength relatively smaller than that of the dielectric but a relatively large dielectric constant, and having an average dielectric constant in the plane direction of 30 or more. In the device.

According to a second aspect of the present invention, in the first aspect, the second substrate is selected from titanium oxide or a metal titanate compound such as barium titanate, calcium titanate, and strontium titanate. A surface reforming apparatus characterized in that:

According to a third aspect of the present invention, in the first or second aspect, the first substrate is selected from the group consisting of magnesium oxide, aluminum oxide, glass, and zirconia. In the surface modification device.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the dielectric member is formed by dispersing the second base material in the first base material. Characteristic surface modification equipment.

According to a fifth aspect of the present invention, in any one of the first to third aspects, the dielectric member is obtained by partially coating the member made of the first base material with the second base material. A surface reforming apparatus characterized in that:

According to a sixth aspect of the present invention, a flat plate-shaped first electrode and a second electrode facing each other and a dielectric member interposed between the first and second electrodes are used. An object to be processed is held between the first and second electrodes, and the first and second electrodes are held.
A method in which a high voltage is applied between the electrodes under atmospheric pressure to generate a barrier discharge, thereby modifying the surface of the object to be processed, wherein the first member made of a dielectric is used as the dielectric member And a second base material having a mechanical strength relatively lower than that of the dielectric but a relatively high dielectric constant, and having an average dielectric constant of 30 or more in the plane direction. The surface modification method is characterized by generating

According to a seventh aspect of the present invention, in the sixth aspect, the second substrate is a metal titanate compound such as titanium oxide or barium titanate, calcium titanate, strontium titanate or the like. The characteristic surface modification method.

According to an eighth aspect of the present invention, in the sixth or seventh aspect, the first substrate is selected from the group consisting of magnesium oxide, aluminum oxide, glass and zirconia. In the reforming method.

A ninth aspect of the present invention is the surface modification method according to any one of the sixth to eighth aspects, wherein the second base material is dispersed in the first base material. It is in.

According to a tenth aspect of the present invention, in any one of the sixth to ninth aspects, the second substrate is partially coated on a member made of the first substrate. In the surface modification method.

According to the method of the present invention, the mechanical strength is, for example,
A first base material made of a dielectric material having a relatively high bending strength of about 100 Mpa or more, and a mechanical strength is relatively low,
By using a composite dielectric member in which a dielectric material having a dielectric constant relatively higher than that of the first base material, that is, a second base material made of a so-called ferroelectric material is used, dielectric breakdown is less likely to occur and plasma generated is less likely to occur. A composite barrier discharge having a high energy density can be realized.

Here, the composite barrier discharge means a minute discharge column.
Form a lightning discharge column on a conventional barrier discharge
Glow discharge area
10 ^-4-10^-1A / cm²To maintain barrier discharge mode
In the composite barrier discharge, the body of the plasma
Product and high energy.

In the surface fluorination reaction by plasma treatment under atmospheric pressure, if the relative dielectric constant of the dielectric is less than 10,
The etching reaction of the surface occurs earlier than the decomposition of fluorine gas, and the surface is not hydrophobized, but the surface is hydrophilized,
Several minutes of plasma discharge treatment time are required until hydrophobicity of the surface is observed. However, when a dielectric having a relative dielectric constant of 30 or more is used, the surface is not hydrophilized, and the surface is hydrophobized in a few seconds. Therefore, in the present invention, in order to realize a good composite barrier discharge, it is preferable that the average dielectric constant in the plane direction of the dielectric member is 30 or more.

The first base material used in the present invention has a relatively low dielectric constant but a relatively high mechanical strength than the second base material, for example, a bending strength of about 150 Mpa or more.
Preferably, it is a dielectric material of 200 MPa or more, and examples thereof include magnesium oxide, aluminum oxide, and glass.

The second base material is not limited as long as it is a dielectric material having a ferroelectric constant as much as possible. Particularly preferred materials are ferroelectric materials such as titanium oxide, barium titanate, calcium titanate and titanium. And metal titanate compounds such as strontium acid.

The average dielectric constant in the plane direction of the dielectric member obtained by combining the first base material and the second base material is 30 or more, preferably 5 or more.
It is good to be 0 or more, more preferably 100 or more. Further, the mechanical strength is 150 MPa or more, preferably 200 MPa or more in bending strength. If the bending strength of the dielectric member is less than the above range, dielectric breakdown occurs at the time of plasma discharge, and the desired good composite barrier discharge cannot be obtained.

The first and second substrates may be combined in a form in which fine particles of the second substrate are dispersed as a binder in the first substrate, or the first substrate is dispersed. To partially coat the second substrate, and the like, but the first and second
It is sufficient that both of the base materials are exposed on the surface of the dielectric member, and the present invention is not necessarily limited to these forms. It is preferable to mix the first base material at a ratio of 5% to 40% and the second base material at a ratio of 60% to 95%, but the most preferable ratio is the first base material. 5% to 20%, and the second base material is 80% to 95%.

In the present invention, by using such a composite dielectric material, a composite barrier discharge in which a barrier discharge and a concentrated discharge are combined under atmospheric pressure can be formed, and the discharge starting voltage can be reduced. This has the effect of preventing the dielectric breakdown of the material.

That is, in the present invention, under atmospheric pressure, several tens of k
A composite barrier discharge can be formed with an applied voltage of several kV at a frequency of about Hz, and surface treatment can be performed with high efficiency and in a short time.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on embodiments, but the present invention is not limited to these embodiments.

[First Embodiment] FIG. 1 is a schematic view of a plasma reactor according to the present embodiment. FIG. 2 is a perspective view of the dielectric member.

As shown in these drawings, the surface treatment apparatus according to the present embodiment has a plasma discharge treatment apparatus 20 inside a reaction treatment vessel 10 having a gas introduction pipe 11 and a gas discharge pipe 12. It is. The plasma discharge processing apparatus 20 is a metal plate-type electrode 22 that is a first electrode in a reaction vessel 21 and a second electrode disposed to face the metal plate-type electrode 22 at a predetermined interval. It comprises a metal plate electrode 23, a dielectric member 24A arranged to cover the surface of the metal plate electrode 23, and a power supply unit 25 for applying a voltage between the metal plate electrodes 22 and 23. I do. A discharge space 26 is formed between the metal plate electrode 22 and the dielectric member 24, and the workpiece 30 is placed on the dielectric member 24.

The material of the reaction vessel 21 is not particularly limited as long as it is insulated from the electrodes 22 and 23. For example, Pyrex (registered trademark) glass, acrylic, ceramic, etc. Is mentioned.

Here, the dielectric member 24A is, for example, as shown in FIG.
As shown in the figure, the first base material 41A is attached to the second base material 42A.
In which dielectric fine particles are dispersed. In this case, the second base material 42A is exposed on the surface in a dispersed state.

When such a dielectric member 24A is used, since the second base material 42A is dispersed as fine particles as a binder in the first base material 41A, discharge columns having high energy are mixed during the discharge. It is possible to realize a complex barrier discharge in a form, and to realize high efficiency of surface modification of a substrate.

Further, since the mechanical strength is secured by the first base material 41A, dielectric breakdown does not occur in the dielectric member even when the discharge is repeatedly performed.

When the dielectric member 24A of this embodiment is used, since the average dielectric constant is high while having a predetermined mechanical strength, discharge can be performed at a low driving voltage, and the surface treatment time can be shortened. .

[Second Embodiment] FIG. 3 shows another embodiment of the present invention.

The dielectric member 24B of this embodiment is obtained by partially coating the surface of a first base material 41B with a second base material 42B. Even in such an embodiment, the same effects as those of the first embodiment can be obtained.

That is, since the first base material 41A is partially coated with the second base material 42B, two types of base materials are exposed on the surface of the dielectric member, and as a result, a good composite barrier discharge is realized. Becomes possible. The mechanical strength is the first
Of the base material 41B.

[0039]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

Example 1 Using an apparatus having a flat electrode structure as shown in FIG. 1, fine particles of calcium titanate having an average particle size of about 10 μm were contained in 20 parts by weight of a magnesium oxide dielectric having an average particle size of about 1 μm. The ceramic was fired from 80 parts by weight. The average dielectric constant of this ceramic is 100
Met.

This was used as a dielectric member 24A, and a polyethylene terephthalate film was used as an object to be treated, and the surface of the polyethylene terephthalate substrate was hydrophobized by composite barrier discharge under the following conditions.

The conditions for the surface treatment of the substrate according to this example are shown below.・ Gas composition: CF ₄ / He (5/95) (confinement system) ・ Distance between electrode and workpiece: 1 mm ・ Frequency during processing: 55 kHz ・ Pressure during processing: 760 Torr (atmospheric pressure) ・ Dielectric member: oxidation Magnesium / calcium titanate (20/80) ・ Object to be treated: polyethylene terephthalate (PET) film ・ Irradiation time: 10 seconds to 3 minutes

When the surface treatment of the base material was performed under the above conditions, the dielectric member did not cause dielectric breakdown,
Moreover, the hydrophobicity of the obtained to-be-processed object was also favorable. The result is shown in FIG.

Example 2 Using the same apparatus as in Example 1, a dielectric member 16 was obtained in which the surface of magnesium oxide was partially coated with calcium titanate as a ferroelectric material. The average dielectric constant of this ceramic was 36.3.

A surface treatment was performed under the same conditions as in Example 1 except that this dielectric member 16 was used.

In this example, as in Example 1, the calcium titanate did not cause dielectric breakdown, and the object to be treated had good hydrophobicity. This result is shown in FIG.
Shown in

[Comparative Example 1] The same apparatus as in Example 1 was used, and surface treatment was performed under the same conditions as in Example 1 using alumina (relative dielectric constant: 10) as a dielectric. It took a considerable time for the hydrophilization to proceed and for the hydrophobic treatment to be realized.

[Comparative Example 2] Using the same apparatus as in Example 1 and using zirconia (dielectric constant: 33) as a dielectric, surface treatment was performed under the same conditions as in Example 1. However, dielectric breakdown occurred within several repetitions, and good hydrophobic treatment could not be performed thereafter.

[0049]

As described above, according to the present invention,
Since a ferroelectric material is dispersed or partially coated on the dielectric surface with high mechanical strength, when a high voltage is applied under atmospheric pressure, the ferroelectric material does not cause dielectric breakdown, and the energy of the generated plasma A high-density composite barrier discharge can be realized, and the efficiency of the surface modification of the base material can be increased.

[Brief description of the drawings]

FIG. 1 is a schematic view of a parallel plate type plasma reactor.

FIG. 2 is a dispersion diagram of a dielectric electrode in which ferroelectric particles are dispersed and deposited on the surface.

FIG. 3 is a surface view of a dielectric electrode having a surface partially coated with a ferroelectric material.

FIG. 4 is a graph showing the results of Examples and Comparative Examples.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Reaction processing container 11 Gas introduction pipe 12 Gas exhaust pipe 20 Plasma processing apparatus 21 Reaction vessel 22 Metal plate type electrode 23 Metal plate type electrode 24A, 24B Dielectric member 25 Power supply unit 26 Discharge unit 30 Discharge object

Continued on the front page F-term (reference) 4G031 AA03 AA04 AA05 AA06 AA11 AA12 AA29 BA09 CA08 4G075 AA30 BA05 CA15 CA47 DA02 DA05 EC21 FB04 FC15

Claims (10)

[Claims] A first electrode and a second electrode which are opposed to each other and have a flat plate shape;
Electrodes, a dielectric member interposed between the first and second electrodes, and a potential difference applying means for applying a potential difference between the first and second electrodes. A device for modifying the surface of the object held between the first and second electrodes by applying a high voltage under atmospheric pressure between the electrodes to generate a barrier discharge; The dielectric member is composed of a first base material made of a dielectric, and a second base material having a mechanical strength relatively smaller than that of the dielectric but a relatively large dielectric constant, and is averaged in a plane direction. A surface modifying apparatus having a dielectric constant of 30 or more. 2. The method according to claim 1, wherein the second base material is
A surface reforming device characterized by being selected from titanium oxide or a metal titanate compound such as barium titanate, calcium titanate, and strontium titanate. 3. The method according to claim 1, wherein the first substrate is made of magnesium oxide, aluminum oxide, glass,
And a zirconia group. 4. The surface reforming apparatus according to claim 1, wherein the dielectric member is formed by dispersing the second base material in the first base material. 5. The dielectric member according to claim 1, wherein the dielectric member is obtained by partially coating the member made of the first base material with the second base material. Surface modification equipment. 6. A flat plate-shaped first electrode and a second plate which face each other.
And a dielectric member interposed between the first and second electrodes, and holding the object to be processed between the first and second electrodes, By applying a high voltage between the electrodes under atmospheric pressure to generate a barrier discharge, in the method of modifying the surface of the object to be processed, the dielectric member may include a first substrate made of a dielectric material. A composite barrier discharge is formed by using a second base material having a mechanical strength relatively smaller than that of the dielectric but a relatively large dielectric constant and having an average dielectric constant of 30 or more in a plane direction. A surface modification method characterized by causing the surface modification. 7. The method according to claim 6, wherein the second base material is
A surface modification method characterized by using a metal titanate compound such as titanium oxide or barium titanate, calcium titanate, or strontium titanate. 8. The method according to claim 6, wherein the first substrate is made of magnesium oxide, aluminum oxide, glass,
A surface modification device selected from compounds such as zirconia. 9. The method according to claim 6, wherein the second base material is dispersed in the first base material. 10. The surface modification method according to claim 6, wherein the second substrate is partially coated on a member made of the first substrate.