JPH1036537A - Discharge plasma treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of stable discharge plasma treatment designed to generate uniform discharge plasma under a pressure close to the atmospheric pressure irrespective of ambient gas in conducting the treatment. SOLUTION: A solid dielectric 6 with a dielectric constant of >=10 at an ambient temperature of 25 deg.C is set up on at least one facing surface of a pair of electrodes 4, 5 standing against each other, a base material is placed between one party of the electrodes (e.g. electrode 4) and the solid dielectric 6 or between the solid dielectrics 6, and the surface of the base material 7 is treated under a pressure close to the atmospheric pressure with the discharge plasma generated by applying pulsed electric field between the pair of electrodes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge plasma processing method under a pressure near atmospheric pressure.

[0002]

2. Description of the Related Art Conventionally, a method of generating a glow discharge plasma under a low pressure condition to perform surface modification has been put to practical use. However, treatment under low-pressure conditions is industrially disadvantageous, and is therefore applied only to expensive treated products such as electronic components. For this reason, a method of generating discharge plasma under a pressure near the atmospheric pressure has been proposed. For example, a method of performing treatment in a helium gas atmosphere is disclosed in JP-A-2-48626, and a method of performing treatment in an atmosphere containing argon gas, acetone gas and / or helium gas is disclosed in JP-A-4-74525. Have been.

However, all of the above methods generate plasma in a gas atmosphere containing helium gas or ketones, and the gas atmosphere is limited. Helium gas is industrially disadvantageous because it is expensive, and when an organic compound is contained, the organic compound itself often reacts with the object to be treated, so that the desired surface modification treatment cannot be performed. is there.

[0004]

SUMMARY OF THE INVENTION In view of the above problems, the present invention generates a uniform discharge plasma under a pressure near the atmospheric pressure regardless of the gas atmosphere at the time of processing, and stably performs the discharge plasma processing. Provide a way to do it.

[0005]

According to the discharge plasma processing method of the present invention, a solid dielectric is provided on at least one of the opposed surfaces of a pair of opposed electrodes, and one of the electrodes is connected to the solid dielectric or the solid dielectric. A substrate is placed between the electrodes, and a process is performed using a discharge plasma generated by applying a pulsed electric field between the pair of electrodes under a pressure near the atmospheric pressure.

The above-mentioned pressure near the atmospheric pressure is defined as 100 to 8
Refers to a pressure of 00 Torr. The pressure is preferably in the range of 700 to 780 Torr, which facilitates pressure adjustment and makes the apparatus simple.

It is known that under a pressure near the atmospheric pressure, a plasma discharge state is not stably maintained except for the above-mentioned specific gases such as helium gas and ketones, and an instantaneous transition to an arc discharge state occurs. By applying a pulsed electric field, it is considered that a cycle in which the discharge is stopped before the transition to the arc discharge and the discharge is started again is realized.

Under pressures near atmospheric pressure, for the first time, the method of applying a pulsed electric field of the present invention
It is possible to stably generate discharge plasma even in an atmosphere that does not contain a gas component such as helium gas, ketones, or the like, which changes from a plasma discharge state to an arc discharge state for a long time.

[0009] According to the method of the present invention, it is also possible to generate discharge plasma in air. The plasma treatment under the known low pressure condition, as well as the plasma treatment under the atmospheric pressure condition to contain the specific gas, it was essential to perform the treatment in a closed container shielded from the outside air, According to the discharge plasma processing method, processing in an open system becomes possible.

Furthermore, since a high-density plasma state can be realized by the method of applying a pulsed electric field, it has great significance in performing an industrial process such as continuous processing.

FIG. 1 shows an example of a pulse voltage waveform. The waveforms (a) and (b) are impulse waveforms, the waveform (c) is a pulse waveform, and the waveform (d) is a modulation waveform. Although FIG. 1 shows a case where the voltage application is repeated positive and negative, a pulse of a type that applies a voltage to either the positive or negative polarity side may be used. FIG. 2 shows a block diagram of a power supply when such a pulse voltage is applied.

Although the pulse voltage waveform in the present invention is not limited to the above-mentioned waveforms, the shorter the rise time of the pulse, the more efficiently the ionization of the gas during the generation of the plasma. Since the rise time is determined by the power supply to be used, a power supply having a rise time as short as possible is selected.

Further, the modulation may be performed using pulses having different pulse waveforms, rise times, and frequencies. Such modulation is effective in performing high-speed continuous surface treatment.
Also, a higher pulse frequency and a shorter pulse width are suitable for high-speed continuous surface treatment.

The above discharge is performed by applying a voltage.
The magnitude of the voltage is determined as appropriate, but is preferably in a range where the electric field strength is 1 to 40 kV / cm when applied to the electrode. If it is less than 1 kV / cm, it takes too much time for the treatment, and if it exceeds 40 kV / cm, arc discharge occurs. In applying the voltage, a direct current may be superimposed.

[0015] The plasma generation method of the present invention is performed in an apparatus having a pair of opposing electrodes, and a solid dielectric placed on at least one of the opposing surfaces of the electrodes. The portion where plasma is generated is between the solid dielectric and the electrode when a solid dielectric is installed on one of the electrodes, and between the solid dielectrics when the solid dielectric is installed on both of the electrodes. Space.

Examples of the electrodes include those made of simple metals such as copper and aluminum, alloys such as stainless steel and brass, and intermetallic compounds. It is preferable that the counter electrode has a structure in which the distance between the counter electrodes is substantially constant in order to avoid occurrence of arc discharge due to electric field concentration. Examples of an electrode structure that satisfies this condition include a parallel plate type, a cylindrical opposed plate type, a spherical opposed plate type, a hyperboloid opposed plate type, and a coaxial cylindrical structure.

The solid dielectric is provided on one or both of the opposing surfaces of the electrode. At this time, the electrode on the side on which the solid dielectric is placed is in close contact with the electrode, and the opposing surface of the contacting electrode is completely covered. This is because if there is a portion where the electrodes directly face each other without being covered by the solid dielectric, an arc discharge occurs therefrom.

Examples of the solid dielectric include plastics such as polytetrafluoroethylene and polyethylene terephthalate, glass, metal oxides such as silicon dioxide, aluminum oxide, zirconium dioxide and titanium dioxide, and double oxides such as barium titanate. No. In particular, according to the solid dielectric having a relative dielectric constant of 10 or more, high-density discharge plasma can be generated even at a low voltage.

The discharge plasma treatment method according to the first aspect of the present invention has been made in view of this point, and has a dielectric constant of 10 or more (25 or more) on at least one opposing surface of a pair of opposing electrodes.
C) environment, a substrate is placed between one electrode and the solid dielectric or between the solid dielectrics, and a pulse is applied between the pair of electrodes under a pressure near atmospheric pressure. The method is characterized in that the substrate surface is treated with discharge plasma generated by applying a converted electric field.

When the relative dielectric constant is 10 or more, a high-density discharge plasma can be generated at a low voltage, and surface treatment and high-speed front and back treatment can be performed in a short time. It becomes difficult to perform such a surface treatment.
Although the upper limit of the relative permittivity is not particularly limited, about 18,500 of actual materials are known. Particularly preferably, the dielectric constant is 10 to 100. Examples of such a solid dielectric include metal oxides such as zirconium dioxide and titanium dioxide, and double oxides such as barium titanate.

The titanate compound is known as a ferroelectric substance. In the case of TiO ₂ alone, the relative permittivity differs depending on the crystal structure, and the relative permittivity is about 80 in the rutile type crystal structure.
In the case of a compound of TiO ₂ and at least one selected from oxides of metals such as Ba, Sr, Pb, Ca, Mg, and Zr, the relative dielectric constant is about 2,000 to 18,500. The relative dielectric constant can be changed depending on purity and crystallinity.

On the other hand, in the case of TiO ₂ alone, the composition changes drastically under the heating environment. For example, when heated in a reducing atmosphere, the use environment is restricted due to the occurrence of oxygen deficiency, and the ordinary film forming method is Specific resistance is 10 ⁴ Ω · c
Since the film has a thickness of about m, it is easy to shift to arc discharge by applying a voltage, and care must be taken. Therefore preferable to use contain a Al ₂ O ₃ than TiO ₂ alone is good, titanium oxide 5 to 50 wt%, aluminum oxide 50 to 95 wt%
Are more preferable because they are thermally stable.

The discharge plasma processing method according to the second aspect of the present invention has been made in view of this point. In the discharge plasma processing method, a solid dielectric is provided on at least one of the opposing surfaces of a pair of electrodes facing each other. Discharge generated by applying a pulsed electric field between the pair of electrodes under a pressure near atmospheric pressure by disposing a base material between the electrodes and the solid dielectric or between the solid dielectrics. A discharge plasma treatment method for treating a substrate surface with plasma, wherein the solid dielectric comprises 5 to 50% by weight of titanium oxide and 5 to 50% by weight of aluminum oxide.
0 to 95% by weight, and the coating thickness is 10 to 1,0
It is characterized by being a metal oxide film having a thickness of 00 μm.

The metal oxide film having such a composition range is as follows:
It is thermally stable, has a relative dielectric constant of about 10 to 14, and a specific resistance of about 10 ^10, and does not generate arc discharge. If the proportion of aluminum oxide is less than 50% by weight, arc discharge is likely to occur, and if it exceeds 95% by weight, the relative dielectric constant becomes about 7 and a high applied voltage is required to generate discharge plasma.

Further, the discharge plasma processing method of the third aspect of the present invention
A solid dielectric is provided on at least one of the opposing surfaces of the pair of electrodes facing each other, and a substrate is placed between one of the electrodes and the solid dielectric or the solid dielectric, and under a pressure near atmospheric pressure,
A discharge plasma treatment method for treating a substrate surface with a discharge plasma generated by applying a pulsed electric field between the pair of electrodes, wherein the solid dielectric contains zirconium oxide, and has a coating thickness. Is 10-1,
It is a metal oxide film having a thickness of 000 μm.

When zirconium oxide alone is used, it has a relative dielectric constant of about 12, which is advantageous for generating discharge plasma at a low voltage. Usually, zirconium oxide is yttrium oxide (Y ₂ O ₃ ), calcium carbonate (Ca)
30% by weight of CO ₃ ), magnesium oxide (MgO), etc.
, The expansion and shrinkage due to the crystal transformation are prevented and stabilized, but such additives may be added. The relative dielectric constant is determined by the type of the additive and the crystallinity of the metal oxide, and it is preferable that at least 70% by weight be zirconium oxide. For example, a zirconium oxide film to which yttrium oxide is added in an amount of 4 to 20% by weight is preferable because its relative dielectric constant is about 8 to 16.

The shape of the solid dielectric may be a sheet or a film, but preferably has a thickness of 0.01 to 4 mm. If the thickness is too large, a high voltage is required to generate the induced discharge plasma. If the thickness is too small, dielectric breakdown occurs when a voltage is applied, and arc discharge occurs. The solid dielectric may be used in the form of a film on a conductor such as carbon steel or directly on an electrode. In this case, the thickness of the coating is
If the thickness is too thin, discharge plasma is easily generated, but if it is too thin, arc discharge occurs, and if it is too thick, dielectric loss increases, discharge plasma hardly occurs, and it becomes high temperature or cracks occur in the coating, It is preferably between 10 and 1,000 μm, more preferably between 50 and 700 μm. A metal oxide film having a uniform thickness is preferable because the resulting discharge plasma becomes uniform.

The distance between the electrodes is determined by the thickness of the solid dielectric,
It is determined in consideration of the magnitude of the applied voltage, the purpose of utilizing the plasma, and the like, and is preferably 1 to 50 mm.
If it is less than 1 mm, it is not enough to place the electrodes at intervals. If it exceeds 50 mm, it is difficult to generate uniform discharge plasma.

The discharge plasma generated by the method of the present invention can be applied to various fields. Examples include surface modification using the reaction between the species excited by the discharge plasma and the substrate surface, decomposition and removal of nitrogen oxides by generating discharge plasma in the presence of nitrogen oxides, and light sources. Can be used.

Hereinafter, a method of treating the surface of a base material by a discharge plasma treatment method will be described in detail. The discharge plasma treatment method of the present invention has a pair of opposed electrodes, and in a device in which a solid dielectric is provided on at least one of the opposed surfaces of the electrodes, when a solid dielectric is provided on one of the electrodes, When a solid dielectric is installed in the space between the solid dielectric and the electrode, or in both of the above electrodes, the base material is installed in the space between the solid dielectrics, and the surface of the base material is treated by discharge plasma generated in the space. Is what you do.

Examples of the substrate to be subjected to the surface treatment of the present invention include plastics such as polyethylene, polypropylene, polystyrene, polycarbonate, polyethylene terephthalate, polytetrafluoroethylene, and acrylic resin, glass, ceramic, and metal. Examples of the shape of the substrate include a plate shape and a film shape, but are not particularly limited thereto. According to the discharge plasma treatment method of the present invention, it is possible to easily cope with treatment of substrates having various shapes.

In the surface treatment, a gas existing in the discharge plasma generation space (hereinafter, referred to as a processing gas)
Any processing is possible by selecting.

By using a fluorine-containing compound gas as the above-mentioned processing gas, a fluorine-containing group can be formed on the substrate surface to lower the surface energy and obtain a water-repellent surface.

Examples of the fluorine-containing compound include carbon tetrafluoride (CF ₄ ), carbon hexafluoride (C ₂ F ₆ ), propylene hexafluoride (CF ₃ CFCF ₂ ), and cyclobutane octafluoride (C ₄ F ₈ ) Fluorine-carbon compounds such as monochloride
Halogen, such as fluorocarbon (CClF ₃₎ - carbon compound,
6 fluoride such as sulfur hexafluoride (SF ₆₎ - sulfur compounds and the like. From the viewpoint of safety, it is preferable to use carbon tetrafluoride, carbon hexafluoride, propylene hexafluoride, and cyclobutane 8-fluoride which do not generate hydrogen fluoride which is a harmful gas.

A hydrophilic functional group such as a carbonyl group, a hydroxyl group or an amino group is formed on the surface of a substrate by using a compound containing an oxygen element, a compound containing a nitrogen element, or a compound containing a sulfur element as a processing gas as described below. As a result, the surface energy can be increased, and a hydrophilic surface can be obtained.

Examples of the oxygen element-containing compound include oxygen,
Oxygen elements such as ozone, water (steam), carbon monoxide, carbon dioxide, nitric oxide, nitrogen dioxide, alcohols such as methanol and ethanol, ketones such as acetone and methyl ethyl ketone, and aldehydes such as methanal and ethanal. And the like. These may be used alone or in combination of two or more. Further, the oxygen element-containing compound and hydrogen may be mixed and used. Further, the oxygen-containing compound and a gas of a hydrocarbon compound such as methane and ethane may be mixed and used. Addition of the fluorine element-containing compound at 50% by volume or less to the oxygen element-containing compound promotes hydrophilicity. As the fluorine element-containing compound, the same compounds as those exemplified above may be used.

As the nitrogen-containing compound, nitrogen,
Ammonia and the like. The nitrogen element-containing compound and hydrogen may be used as a mixture.

Examples of the sulfur-containing compound include sulfur dioxide and sulfur trioxide. Further, sulfuric acid can be vaporized and used. These may be used alone or in combination of two or more.

Further, by performing the treatment in an atmosphere of a monomer having a hydrophilic group and a polymerizable unsaturated bond in the molecule,
A hydrophilic polymer film can also be deposited. As the hydrophilic group, a hydroxyl group, a sulfonic acid group, a sulfonate group,
Examples include a hydrophilic group such as a primary, secondary, or tertiary amino group, an amide group, a quaternary ammonium base, a carboxylic acid group, and a carboxylic acid group. Further, even when a monomer having a polyethylene glycol chain is used, a hydrophilic polymer film can be similarly deposited.

The above monomers include acrylic acid, methacrylic acid, acrylamide, methacrylamide, N, N
-Dimethylacrylamide, sodium acrylate, sodium methacrylate, potassium acrylate, potassium methacrylate, sodium styrenesulfonate, allyl alcohol, allylamine, polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, and the like. These monomers are
Used alone or as a mixture.

Since the above-mentioned hydrophilic monomer is generally a solid, it is used by dissolving it in a solvent and evaporating it by a means such as reduced pressure. Examples of the solvent include organic solvents such as methanol, ethanol, and acetone, water, and mixtures thereof.

Further, using a processing gas such as a metal-hydrogen compound, a metal-halogen compound, or a metal alcoholate of a metal such as Si, Ti, or Sn, SiO ₂ , TiO ₂ , Sn
By forming a thin film of a metal oxide such as O ₂ , electrical and optical functions can be given to the substrate surface.

From the viewpoint of economy and safety, it is preferable to carry out the treatment in an atmosphere in which the above-mentioned treatment gas is diluted with an inert gas. Examples of the inert gas include rare gases such as helium gas, neon gas, argon gas, and xenon gas, and nitrogen gas. These alone are 2
Mixtures of more than one species may be used. Conventionally, at a pressure close to the atmospheric pressure, processing has been performed in the presence of helium gas. However, according to the discharge plasma processing method of the present invention 6,
Stable surface treatment in argon gas or nitrogen gas, which is less expensive than helium gas, is possible and has great industrial advantages.

FIG. 3 shows an example of an apparatus for performing the discharge plasma processing method of the present invention. In this device, the lower electrode 5
The solid dielectric 6 is provided on the upper surface, and discharge plasma is generated in the space 3 between the solid dielectric 6 and the upper electrode 4. The container 2 includes a gas introduction pipe 8, a gas exhaust port 10, and a gas exhaust port 1.
The processing gas is supplied from the gas introduction pipe 8 to the discharge plasma generation space 3. In the present invention, since the portion in contact with the generated discharge plasma is processed, the upper surface of the substrate 7 is processed in the example of FIG. If it is desired to treat both surfaces of the base material, the base material may be set up in the discharge plasma generation space 3.

It is preferable that the processing gas is uniformly supplied to the plasma generation space. When processing in a mixed gas of a processing gas and an inert gas, since the inert gas is lighter than the processing gas, a device must be devised to avoid non-uniformity during supply. In particular, when treating a substrate having a large area, care must be taken since the substrate tends to be uneven. In the example shown in the apparatus of FIG. 3, a gas introduction tube 8 is connected to the electrode 4 having a porous structure, and a processing gas is supplied to the plasma generation space 3 from above the substrate through the hole of the electrode 4. The inert gas is separately supplied through an inert gas introduction pipe 9.

In order for the reaction gas to be uniformly diffused and supplied to the plasma generation space 3 and to increase its use efficiency, the second solid dielectric material 15 selected from the above-mentioned solid dielectric materials is used.
There is a method of covering the plasma generation space 3 (see FIG. 5). Since the processing gas only needs to be supplied to the enclosed space 3, the supply amount of the gas can be reduced, and the uniformity can be further improved. The structure is not limited to such a structure as long as the gas can be supplied uniformly, and a means such as stirring or blowing the gas at a high speed may be used.

The material of the container 2 includes, for example, resin and glass, but is not particularly limited. Metals such as stainless steel and aluminum can also be used as long as they have a structure insulated from the electrodes.

The discharge plasma treatment of the present invention may be carried out by heating or cooling the substrate, but is sufficiently possible at room temperature. The time required for the discharge plasma treatment is the applied voltage,
It is appropriately determined in consideration of the type of the processing gas, the ratio in the mixed gas, and the like.

Further, utilizing the fact that the surface of the base material is activated by the discharge plasma treatment, a hydrophilic monomer can be reacted using this as a reaction starting point. Invention 4
The discharge plasma processing method of the present invention has been made in view of this point, a solid dielectric is provided on at least one of the opposing surfaces of a pair of electrodes facing each other, and one of the electrodes and the solid dielectric or the solid dielectric A first step of disposing a base material between them and treating the base material surface with a discharge plasma generated by applying a pulsed electric field between the pair of electrodes under a pressure near the atmospheric pressure; And a second step of immersing the substrate in a hydrophilic monomer solution and heating.

In the first step, the discharge plasma generated by maintaining the argon gas and / or the nitrogen gas or the mixed gas of the argon gas and / or the nitrogen gas and the oxygen-containing gas at a pressure near the atmospheric pressure is used. Thus, a radical layer or a peroxide layer is formed on the substrate surface to activate the substrate surface.

An argon gas and / or a nitrogen gas;
It is preferable to use a mixed gas with an oxygen-containing gas because the formation of a radical layer and an oxide layer is facilitated. Examples of the oxygen-containing gas include oxygen, ozone, carbon monoxide,
Gases such as carbon dioxide, nitric oxide and nitrogen dioxide are mentioned, and these may be used alone or in combination of two or more.

When the above-mentioned mixed gas is used, activation is promoted by using a fluorine-containing gas (described above) at a volume ratio of 50% or less with respect to the oxygen-containing gas. In the second step, the surface-activated substrate obtained in the first step is immersed in a hydrophilic monomer liquid and heated to react the hydrophilic monomer at active points on the substrate surface. Let it.

The hydrophilic monomer includes, as a hydrophilic group, a hydroxyl group, a sulfonic acid or a sulfonate group,
Those having a secondary or tertiary amino group, an amide group, a quaternary ammonium group, a carboxylic acid group or a carboxylic acid group, a polyethylene glycol chain, or the like, or vinyl acetate or acrylic acid, whose polymer becomes hydrophilic by a chemical reaction after polymerization Esters and the like.

Specific examples of the hydrophilic monomer include:
(Meth) acrylic acid, (meth) acrylamide, propionamide, sodium (meth) acrylate, potassium acrylate, sodium styrenesulfonate, methyl acrylate, polyethylene glycol di (meth) acrylate, 2-hydroxyethyl methacrylate,
Examples thereof include 2-hydroxymethyl acrylate, and these may be used alone or in combination of two or more.

The above hydrophilic monomer is dissolved in a solvent and used as a solution. As the solvent, an organic solvent such as methanol, ethanol, acetone or the like or water is used. The monomer concentration in the solution is not particularly limited, but the thinner the reaction time, the longer the time required for the reaction becomes longer, and the thicker the unreacted monomer remains in the solvent in large quantities. Is preferably 5 to 30% by weight, depending on the type of the monomer.

The reaction is promoted by activating the surface in the first step, immersing the substrate in the hydrophilic monomer solution and heating. The heating temperature at the time of the reaction is preferably as high as possible, since the reaction is accelerated. However, since it has an adverse effect on the substrate, it is preferable to heat the substrate at a temperature equal to or lower than the heat resistant temperature of the substrate. When the monomer or the homopolymer is physically adsorbed, the immersion time in the hydrophilic monomer solution can be removed by washing with water or an organic solvent if necessary.

A functional layer can also be formed on a substrate by generating plasma while a monomer exhibiting properties such as hydrophilicity and water repellency is adhered to the surface of the substrate. The discharge plasma treatment method of the fifth aspect of the present invention has been made in view of this point. A solid dielectric is provided on at least one of the opposing surfaces of a pair of electrodes facing each other, and one of the electrodes and the solid dielectric or the solid dielectric are disposed. A discharge in which a substrate is disposed between solid dielectrics and a surface of the substrate is treated by a discharge plasma generated by applying a pulsed electric field between the pair of electrodes under a pressure near the atmospheric pressure. A plasma processing method, wherein the processing is performed in a state where a radical reactive monomer is attached to the surface of the substrate.

In the first step of the fifth invention, a radical-reactive monomer is attached to the surface of the substrate. In the present invention 5, the radical-reactive monomer refers to a monomer having a site capable of generating a radical upon contact with plasma, for example, an unsaturated bond such as a double bond or a triple bond, a peroxide, Those containing one or more bonds and the like are preferably used.

Examples of such radically reactive monomers include (meth) acrylic acid, (meth) acrylamide, sodium (meth) acrylate, potassium acrylate, methyl (meth) acrylate, and ethyl (meth) acrylate. , (Meth) acrylonitrile, vinyl acetate, styrene, pentadecafluoroethyl acrylate, trifluorochloroethylene, trifluoroethyl methacrylate and the like, and these may be used alone or in combination of two or more.

In the case of performing a water-repellent treatment, the radical-reactive monomer is particularly preferably a hydrophobic monomer having an unsaturated bond and capable of forming a thick water-repellent layer by a polymerization reaction. However, it does not have to be hydrophobic,
For example, even when a hydrophilic monomer is used, the monomer is fluorinated by performing plasma treatment in a fluorine-containing atmosphere, so that a water-repellent layer can be formed on the substrate surface.

The radical-reactive monomer may be used as it is, or may be used after being dissolved in a solvent. As the solvent, an organic solvent having a high solubility of the radical-reactive monomer can be used. However, it is preferable to use an organic solvent having a low boiling point and easy drying such as methanol, ethanol, and acetone. If the surface of the substrate is significantly damaged by these solvents, water may be used.

The method for adhering the above-mentioned radical-reactive monomer to the substrate is not particularly limited. For example, when a liquid monomer or a monomer solution is used, the substrate is immersed in a liquid, a brush or the like is used. A method of applying to the surface, a method of spraying with a spray or the like, and the like can be given. When the radical reactive monomer is attached to the substrate surface using a monomer solution or a liquid monomer, the solvent attached to the substrate may be dried by a known method, if necessary. When a solid monomer powder is used, it may be sprayed on the surface of the base material using a sieve or the like.

In the second step of the present invention 5, the substrate on which the radical-reactive monomer is adhered in the first step is subjected to a water-repellent treatment or a hydrophilic treatment by the discharge plasma generated by the above-mentioned method to repel the substrate. A water treatment layer and a hydrophilic treatment layer are formed.
When performing a water-repellent treatment, for example, according to the method described above, for example,
By performing the discharge plasma treatment in an atmosphere containing a fluorine-containing gas, a layer having a fluorine-containing water-repellent polar group is formed.

When the hydrophilic treatment is performed, for example, argon gas and / or nitrogen gas, or
By performing discharge plasma treatment in an atmosphere of a mixed gas of the gas and the oxygen-containing gas or a mixed gas of a gas composed of nitrogen and hydrogen, a layer having a hydrophilic polar group containing oxygen and / or nitrogen is formed. It is formed.

The use of a mixed gas with an oxygen-containing gas is preferred because the formation of a radical layer and an oxide layer is facilitated. Examples of the oxygen-containing gas include gases such as oxygen, ozone, water vapor, carbon monoxide, carbon dioxide, nitrogen monoxide, and nitrogen dioxide, and these may be used alone or in combination of two or more. Is also good. When the above-mentioned mixed gas is used, the use of a fluorine-containing gas (described above) having a volume ratio of 50% or less with respect to the oxygen-containing gas further promotes hydrophilization. Examples of the gas composed of nitrogen and hydrogen include, in addition to ammonia gas, nitrogen gas or a mixed gas of ammonia gas and hydrogen gas.

When a mixed gas of the above-mentioned nitrogen gas or ammonia gas and hydrogen gas is used, its composition is appropriately determined depending on the type of the substrate to be treated and the plasma treatment conditions. The value of N / (N + H) is preferably 1/4 or more, more preferably 1/2 to 1. Here, in the gas composed of nitrogen and hydrogen, N represents the number of nitrogen atoms, and H represents the number of hydrogen atoms.

[0067]

【Example】

Example 1 In the apparatus of FIG. 3 (made of Pyrex glass, capacity: 5 L), the upper electrode 4 [stainless steel (SUS
304), size: 80 mm x 80 mm, diameter 1 mm
Are arranged at intervals of 10 mm) and the lower electrode 5 (made of stainless steel (SUS304), size: 80 mm × 80 mm), on a lower electrode in a space with a distance of 6 mm between the electrodes, is made of TiO having a rutile crystal structure as a solid dielectric. ₂ sintered body (thickness: 2m
m, diameter: 120 mm, relative dielectric constant of about 70)
And a polyethylene terephthalate (PET) base material (manufactured by Toray, "Lumirror T5")
0 ", size: 100 mm x 100 mm, thickness: 50μ
m).

The inside of the apparatus was evacuated with an oil rotary pump until the pressure became 1 Torr. Next, nitrogen gas is introduced into the inert gas introduction pipe 9.
And introduced until the inside of the apparatus reaches 760 Torr. A discharge plasma is generated by applying a pulsed electric field having the waveform, peak value, frequency, and pulse width shown in Table 1 between the upper electrode 4 and the lower electrode 5 for 15 seconds, and this is brought into contact with a PET base material. A processed product was obtained. The generated plasma was in a uniform (emission) state.

Example 2 As a solid dielectric, carbon steel (SS41, size: 140 mm × 140 mm, thickness:
Titanium oxide 1 on one side of plasma
Using a metal oxide film (relative dielectric constant of about 14) of 3% by weight and aluminum oxide of 87% by weight and having a thickness of 500 μm, the lower metal electrode 5 is formed so that the coating surface faces the upper electrode 4. And the waveform, peak value, frequency, and the like shown in Table 1 between the upper electrode 4 and the lower electrode 5.
A surface-treated product was obtained in the same manner as in Example 1, except that a pulsed electric field having a pulse width was applied for 15 seconds to generate discharge plasma. The generated plasma was in a uniform (emission) state.

Example 3 As a solid dielectric, carbon steel (SS41, size: 140 mm × 140 mm, thickness:
10 mm) on one side by plasma spraying, 8% by weight of Y ₂ O
_A film (relative dielectric constant: 16) formed with a thickness of 500 μm on ZrO containing ₃ was used.
% CF ₄ gas 30 sccm, the total flow rate of argon gas 2970 sccm from the inert gas inlet pipe 9 is 1,000 sccc
m, the upper electrode 4 and the lower electrode 5
In the same manner as in Example 1 except that a pulsed electric field having a waveform, a peak value, a frequency, and a pulse width shown in Table 1 was applied for 15 seconds to generate a discharge plasma, a contact angle of 11 was obtained.
A surface treated product having three degrees of water repellency was obtained. The generated plasma was in a uniform (emission) state.

[Embodiment 4] In Embodiment 3, as shown in FIG. 5, a second solid dielectric 15 is provided between the upper electrode 4 and the solid dielectric 6 (the base material is already provided). Diameter 80m
A cylindrical body made of polytetrafluoroethylene having a size of mx 75 mm in inside diameter x 5 mm in height was inserted, and a total flow rate of 10 sccm of 3% CF ₄ gas and 100 sccm of argon gas was 1
Example 1 was the same as Example 1 except that 10 sccm was introduced and a pulsed electric field having the waveform, peak value, frequency, and pulse width shown in Table 1 was applied between the lower electrodes 5 for 15 seconds to generate discharge plasma. Similarly, a water-repellent surface-treated product having a contact angle of 114 degrees was obtained. The generated plasma was in a uniform (emission) state.

Comparative Example As a solid dielectric, instead of a pulsed electric field, a peak value of 9.0 kV and a frequency of 15.
A processed product was obtained in the same manner as in Example 1, except that discharge was performed using an AC voltage having a sin waveform of 0 kHz. A non-uniform discharge state where many streamers were observed was confirmed.

<Evaluation of Contact Angle> A 2 μl water drop was dropped on the surface to be treated of each of the processed products of Examples 1 to 4 and Comparative Example, and a contact angle measuring device (trade name: CA-X150, manufactured by Kyowa Interface Science Co., Ltd.) was used. To measure the static contact angle. Table 1 shows the results. The treated products of Examples 1 to 4 under a nitrogen atmosphere showed a substantially constant low or high contact angle on the entire surface of the base material, and it was confirmed that a favorable hydrophilic treatment or water-repellent treatment was performed. On the other hand, the processed product of the comparative example in which an uneven discharge state was confirmed was 40 to 60.
The degree was within the range, and uniform processing was not performed.

[0074]

[Table 1]

Example 5 (Step 1) Argon gas was introduced from the inert gas introduction pipe 9 to atmospheric pressure, the flow rate was adjusted to 1005 sccm of argon gas, and a wave was applied between the upper electrode 4 and the lower electrode 5. High price4.
A surface treatment of the PET substrate was performed in the same manner as in Example 1 except that a pulsed electric field having a frequency of 5 kV, a frequency of 3.5 kHz, and a pulse width of 160 μs was applied and the discharge plasma treatment was performed for 15 seconds.

(Step 2) PET surface-treated in step 1
The substrate was immersed in a degassed 10% by weight aqueous solution of sodium styrenesulfonate, and reacted at 50 ° C. for 2 hours. After the reaction is completed, perform washing with hot water and ultrasonic washing with water,
A surface-treated product having a hydrophilicity with a contact angle of 33 degrees was obtained.

Embodiment 6 (Step 1) After introducing 50 sccm of oxygen gas from the gas introduction pipe 8 and 50 sccm of nitrogen gas from the inert gas introduction pipe 9 to atmospheric pressure, the space between the upper electrode 4 and the lower electrode 5 is Peak value 8.5 kV, frequency 7.5 kHz, pulse width 100 μs
The surface treatment of the PET substrate was performed in the same manner as in Example 1 except that the pulsed electric field was applied and the discharge plasma treatment was performed for 15 seconds.

(Step 2) The PET substrate treated in step 1 was immersed in a degassed 10% by weight aqueous solution of acrylamide, and reacted at 70 ° C. for 4 hours. After the completion of the reaction, washing with hot water and ultrasonic washing with water were performed to obtain a hydrophilic surface-treated product having a contact angle of 35 degrees.

[Embodiment 7] 100 mm long x 100 mm wide
× A 50 μm-thick polyethylene film (manufactured by Sumiishi Packaging Co., Ltd., product number “11 ° F”, contact angle 91 °) and a corona discharge treatment device (Kasuga Electric Co., model “HFSS-103”)
And a voltage of 30 kV was applied to perform corona discharge treatment for 15 seconds. Next, an aqueous solution of 10% by weight of acrylamide was sprayed on the obtained film, and allowed to dry at room temperature.

In the same manner as in Example 5, the above substrate was placed so that the surface sprayed with the acrylamide aqueous solution was opposed to the upper electrode 4, and the substrate was treated with discharge plasma in an argon gas atmosphere for 20 seconds. After the treatment, the treated product was washed with water to obtain a hydrophilic surface-treated product having a contact angle of 34 degrees.

Example 8 100 mm × 100 mm
× A 50 μm-thick polyethylene film (manufactured by Sumiishi Packaging Co., Ltd., product number “11 ° F”, contact angle 91 °) and a corona discharge treatment device (Kasuga Electric Co., model “HFSS-103”)
And a voltage of 30 kV was applied to perform corona discharge treatment for 15 seconds. Next, an aqueous solution of 10% by weight of acrylamide was sprayed on the obtained film, and allowed to dry at room temperature.

In the same manner as in Example 6, the above substrate was placed so that the surface sprayed with the acrylamide aqueous solution was opposed to the upper electrode 4, and was treated for 20 seconds by discharge plasma in a mixed gas atmosphere of oxygen and nitrogen. did. After the treatment, the treated product was washed with water to obtain a hydrophilic surface-treated product having a contact angle of 31 °.

[Embodiment 9] 100 mm long x 100 mm wide
× A 50 μm-thick polyethylene film (manufactured by Sumiishi Packaging Co., Ltd., product number “11 ° F”, contact angle 91 °) and a corona discharge treatment device (Kasuga Electric Co., model “HFSS-103”)
And a voltage of 30 kV was applied to perform corona discharge treatment for 15 seconds. Next, a methanol solution of 10% by weight of methyl methacrylate was sprayed on the obtained film, and allowed to dry at room temperature.

In the same manner as in Example 3, the surface on which the methanol solution of methyl methacrylate was sprayed was
And treated for 20 seconds by discharge plasma in a mixed gas atmosphere of CF ₄ and argon gas. After the treatment, the treated product is washed with water and has a contact angle of 1
A surface-treated product having a water repellency of 11 degrees was obtained.

[0085]

According to the method of applying a pulsed electric field as in the present invention, a stable and uniform discharge plasma can be generated under a pressure near the atmospheric pressure regardless of the gas atmosphere. I can do it. Furthermore, since the plasma discharge state can be realized at a high density, high-level processing can be performed in a short time, which is of great significance in performing industrial processes such as high-speed continuous processing.

Further, since the gas atmosphere is not limited, and stable discharge plasma can be generated in the air, the processing can be performed in an open system. Therefore, the field to which the discharge plasma processing can be applied is greatly expanded.

In the first aspect of the present invention, since the solid dielectric having a relative dielectric constant of 10 or more can generate a high-density discharge plasma at a low voltage, the surface treatment and the high-speed surface treatment can be performed in a short time. Can be.

As in the present invention 2 and 3, the solid dielectric is a specific metal oxide film, and the thickness of the metal oxide film is 10 to 1,000 μm, so that the solid dielectric is thermally Is stable, the relative dielectric constant becomes about 10 to 14, and no arc discharge occurs.

As in the present invention 4, the reaction is promoted by immersing the substrate having the activated surface in the first step in a hydrophilic monomer solution and heating the same, whereby a surface-treated product having hydrophilicity can be obtained. .

As in the present invention 5, by subjecting the surface of the substrate to which the monomer is adhered to the discharge plasma treatment, it is possible to obtain a surface-treated product having a good water-repellent treatment or a hydrophilic treatment layer formed thereon.

As in the present invention 6, by generating discharge plasma in an atmosphere composed of argon gas and / or nitrogen gas, stable surface treatment can be performed in a gas which is less expensive than helium gas. It has great industrial advantages.

[Brief description of the drawings]

FIG. 1 is a voltage waveform diagram showing an example of a pulsed electric field.

FIG. 2 is a block diagram of a power supply that generates a pulsed electric field.

FIG. 3 shows an example of the discharge plasma processing apparatus of the present invention.

FIG. 4 shows another example of the discharge plasma processing apparatus of the present invention.

FIG. 5 shows another example of the discharge plasma processing apparatus of the present invention.

[Explanation of symbols]

 1-1 DC power supply 1-2 AC power supply 2 Pyrex glass container 3 Discharge plasma generation space 4 Upper electrode 5 Lower electrode 6 Solid dielectric 7 Base material 8 Gas inlet tube 9 Inert gas inlet tube 10 Gas outlet 11 Exhaust outlet 12-1 Take-up roll 12-2 Take-up roll 13 Film introduction tube 14 Film outlet 15 Second solid dielectric

Claims (6)

[Claims] 1. A solid dielectric having a relative permittivity of 10 or more (under an environment of 25 ° C.) is provided on at least one of opposing surfaces of a pair of opposing electrodes, and one of the electrodes is connected to the solid dielectric or the solid dielectric. A substrate is disposed between the bodies, and the surface of the substrate is treated by a discharge plasma generated by applying a pulsed electric field between the pair of electrodes under a pressure near the atmospheric pressure. Discharge plasma processing method. 2. A solid dielectric is provided on at least one opposing surface of a pair of opposing electrodes, and a base material is disposed between one of the electrodes and the solid dielectric or between the solid dielectrics. A discharge plasma generated by applying a pulsed electric field between the pair of electrodes under the pressure described above, wherein the solid dielectric is made of titanium oxide 5. -50% by weight and 50-95% by weight of aluminum oxide.
A discharge plasma treatment method comprising a metal oxide film having a thickness of 0 to 1,000 μm. 3. A solid dielectric is provided on at least one of the opposed surfaces of a pair of opposed electrodes, and a base material is disposed between one of the electrodes and the solid dielectric or between the solid dielectrics. A discharge plasma treatment method for treating a substrate surface with a discharge plasma generated by applying a pulsed electric field between the pair of electrodes under a pressure of, wherein the solid dielectric comprises zirconium oxide. A discharge plasma treatment method comprising a metal oxide film containing a metal oxide film having a thickness of 10 to 1,000 μm. 4. A solid dielectric is provided on at least one opposing surface of a pair of opposing electrodes, and a base material is disposed between one of the electrodes and the solid dielectric or between the solid dielectrics. A first step of treating the substrate surface with a discharge plasma generated by applying a pulsed electric field between the pair of electrodes under a pressure of, and immersing the substrate in a hydrophilic monomer solution And a heating step. 5. A solid dielectric is provided on at least one opposing surface of a pair of opposing electrodes, and a base material is disposed between one of the electrodes and the solid dielectric or between the solid dielectrics. A discharge plasma treatment method for treating a substrate surface with a discharge plasma generated by applying a pulsed electric field between the pair of electrodes under a pressure of A discharge plasma treatment method, wherein the treatment is performed in a state in which is adhered. 6. The discharge plasma processing method according to claim 1, wherein the discharge plasma is generated in an atmosphere composed of an argon gas and / or a nitrogen gas.