JP2022046346A - Plasma processing apparatus and processing method thereof - Google Patents

Abstract

To provide a method and an apparatus for processing a long sheet, particularly a polymer film surface, with direct plate electrode type barrier discharge scheme atmospheric pressure plasma.SOLUTION: A plasma processing apparatus with a pair of electrodes consisting of a plate-type electrode coated with a dielectric and a metal endless belt forming a parallel gap is used to continuously process, with plasma, a long sheet in a state in which a metal endless belt and the long sheet are in close contact with each other by carrying the long sheet on the metal endless belt, and charging the long sheet on the metal endless belt.SELECTED DRAWING: Figure 1

Description

The present invention relates to a plasma processing apparatus and a processing method for continuously processing a long sheet at atmospheric pressure.

There are inductively coupled coils, microwaves, and barrier discharge electrodes in the method of atmospheric pressure plasma, but atmospheric pressure plasma devices using wide barrier discharge electrodes with a relatively small heat load and a simple structure are widely used. .. The barrier discharge includes a remote type in which plasma generated in the facing electrode gap or an active species generated by the plasma is supplied to the surface to be treated by an air flow, and a direct method in which an object to be treated is placed in the facing electrode gap to treat the surface. There is.

When the long sheet is treated with atmospheric pressure barrier discharge plasma, the treatment is performed while holding the long sheet on the facing roller for the purpose of cooling the long sheet, suppressing wrinkles, maintaining a gap with the plasma electrode, and the like. However, it is difficult to evenly maintain the gap between the plasma electrodes in the transport direction of the long sheet with respect to the curved surface of the facing roller. Therefore, the remote method is often selected as the atmospheric pressure plasma device. However. Compared with the direct method, the remote method has a problem that the processing effect has to be low because the probability that the generated plasma or active species reaches the surface of the object to be processed is low. On the other hand, even in the direct method, there is a method of arranging the electrode shape as an elongated shape such as a wire, a pipe, or a bar in an opposed roll shape, but there is a problem that the processing effect is insufficient because the discharge space is limited.

In Patent Document 1, "a counter electrode composed of a flat plate electrode and a roll electrode facing the flat plate electrode is used, and a conductive layer is provided in a discharge plasma generated by applying an electric field between the flat plate electrode and the roll electrode. In the processing method in which the object to be processed is arranged and plasma processing is performed, the plate electrode is set to the electric field application side, and the object to be processed having a conductive layer between the plate electrode and the roll electrode is brought into contact with the roll electrode. Plasma treatment method characterized by arranging the conductive layer so as to be on the flat plate electrode side and grounding the conductive layer of the object to be treated. A counter electrode composed of a flat plate electrode and a roll electrode facing the flat plate electrode. In a processing method in which an object to be processed having a conductive layer is placed in a discharge plasma generated by applying an electric field between the flat plate electrode and the roll electrode to perform plasma treatment, the flat plate electrode is applied with an electric field. On the side, the object to be treated having a conductive layer between the flat plate electrode and the roll electrode is arranged in a state of being in contact with the roll electrode and so that the conductive layer is on the flat plate electrode side, and the object to be processed is arranged. A plasma treatment method characterized by grounding a conductive layer is disclosed. However, a plate-shaped object to be treated is also used as a counter electrode to form a discharge gap, and a long insulating sheet is provided. When applied to such cases, there is a problem that discharge occurs even on the back surface.

Further, in paragraph [0103] of Patent Document 2, "the base material 1 is conveyed between the applied electrodes 2a and 2b and the ground electrode 5 for holding the base material by a conveying means such as a belt conveyor (not shown). However, it is not disclosed that the belt also serves as an electrode, and the plasma electrode is also a remote method.

2004-207146 Gazette 2004-76076 Gazette

The inventor of the present application treats an electrically insulating long sheet with a direct plate electrode type barrier discharge type atmospheric pressure plasma without causing problems such as thermal deformation, wrinkles, and back surface treatment of the long sheet. We have diligently examined the method and equipment to be used. As a result, the plate-type barrier discharge electrode and the metal endless belt are used as a pair of electrodes, and the long sheet is conveyed on the metal endless belt with the long sheet, and the long sheet is charged on the metal endless belt. It has been found that the problem can be solved by continuously performing plasma treatment on the long sheet in a state where the metal endless belt and the long sheet are in close contact with each other.

An object of the present invention has been made in view of this point, and an object thereof is to provide a method and an apparatus for treating a long sheet, particularly a polymer film surface, with a direct type plate electrode type barrier discharge type atmospheric pressure plasma.

The plasma processing apparatus according to the present invention can generate plasma in an atmospheric pressure atmosphere by using a plate-type electrode coated with a dielectric and a metal endless belt forming a parallel gap as a pair of electrodes. When the driving voltage of the atmospheric pressure plasma is a frequency of 30 kHz to 13.56 MHz, it is easy to generate a uniform plasma. Expectations for discharging are not particularly limited to air, nitrogen, argon, carbon dioxide, hydrogen steam, and a mixed gas using any of these, but if a non-depositible or non-polymerizable gas is used, electrode contamination and particle generation will occur. It is good because it can be suppressed. The waveform may be a sine wave, but a rectangular wave may be used because the plasma is more stable. The metal endless belt may be grounded, or a voltage having the opposite polarity to that of the plate type electrode may be applied. When a voltage is applied to the metal endless belt, power may be supplied directly to the metal endless belt via a brush, or power may be supplied to the roller holding the metal endless belt. Ceramics are preferable as the dielectric covering the plate type electrode from the viewpoint of heat resistance. The ceramics may be bonded to a metal electrode plate or sprayed. As the type of ceramics, alumina-based ceramics are preferable because they have high insulation resistance and mechanical strength. Further, if necessary, it is preferable to use a material having a high relative permittivity such as titanium oxide because it is easy to generate plasma. If the thickness of the dielectric is in the range of 0.2 mm to 1.5 mm, it may be easy to achieve both the withstand voltage and the ease of discharge. Further, a dielectric film may be applied to the outer surface of the metal endless belt with a resin or the like. It is also possible to arrange two or more plate type electrodes for one metal endless belt. Further, if the width of the metal endless belt is wider than the width of the plate type electrode, it is preferable to avoid discharge due to electrolytic concentration at the metal endless belt edge.

The plasma processing apparatus according to the present invention can be provided with a charged electrode facing a metal endless belt on the upstream side of a plate-type electrode coated with a dielectric. In this case, it is preferable to set the metal endless belt to the ground potential because it is easier to control the amount of ions generated by the charged electrode and the amount of the generated ions supplied. Charging electrode The charging electrode is not particularly limited to a wire, a blade, a needle electrode array, or the like, but the needle electrode array may be stable and easy to operate. It is preferable that the voltage applied to the charging electrode is direct current because it is easier to ensure the uniformity of the charging amount in the transport direction when processing while transporting the long sheet. Further, the polarity applied to the charged electrode is not particularly limited, but it may be good because the discharge is easily stabilized when a positive voltage is applied. The distance between the charged electrode and the metal endless belt is preferably about 20 mm to 50 mm. The amount of charge can be adjusted by adjusting the applied voltage.

The plasma processing method according to the present invention uses a plasma processing apparatus in which a metal endless belt forming a parallel gap with a plate-type electrode coated with a dielectric is used as a pair of electrodes, and a long sheet is placed on the metal endless belt. By charging the long sheet on the metal endless belt, the long sheet is continuously plasma-treated with the metal endless belt and the long sheet in close contact with each other. be able to. In order to bring the long sheet into close contact with the metal endless belt, only the Coulomb force generated by charging the long sheet may be used, but the long sheet is metal endless using a nip roller or the like on the upstream side. It may be charged after being brought into close contact with the bell.

According to the present invention, when treating a long sheet, particularly the surface of a polymer film with a direct type plate electrode type barrier discharge type atmospheric pressure plasma, a large area of discharge space can be secured, and wrinkles, thermal deformation, and the back surface of the polymer film can be secured. Problems such as processing can be avoided. In particular, since a sufficient processing space can be secured in the transport direction, it is easy to realize a sufficient processing effect even in high-speed transport.

It is a figure which showed schematically the plasma processing method in one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments. Further, it can be appropriately changed as long as it does not deviate from the range in which the effect of the present invention is exhibited.

FIG. 1 is a diagram schematically showing a plasma processing method according to an embodiment of the present invention. As shown in FIG. 1, the metal endless belt 11 is held by a grounded holding roller 12, and tension is applied by the tension roller 13. One of the holding rollers 12 is a driving roller. The material of the metal belt is not particularly limited, but it is preferable to use a stainless steel belt in terms of corrosion resistance, mechanical strength, heat resistance and the like. Further, if the metal endless belt 11 is a seamless type without a seam, the long sheet 31 is less likely to have uneven processing or wrinkles. The tension of the metal endless belt 11 is preferably set high so that bending and vibration are unlikely to occur, and is preferably in the range of about 200 N / m to 500 N / m.

A plate-type barrier discharge type atmospheric pressure plasma device 3 is installed facing the metal endless belt 11. Alumina is sprayed on the plate electrode 21 with a thickness of 1 mm. The plate electrode 21 is connected to a high-frequency high-voltage power supply 23 and generates plasma 24 in the form of a long sheet. The plasma generation part is covered with a chamber 25, and a mixed gas 26 of nitrogen gas and dry air is supplied from a cylinder. Further, an exhaust device 27 is installed in the chamber 25 in order to exhaust harmful gas such as ozone generated by the plasma 24.

The long sheet 31 is nipated by the holding roller 12 and the nip roller 4 via the metal endless belt 11. As a result, the air between the long sheet 31 and the metal endless belt 11 is largely eliminated. However, in the straight portion of the metal endless belt 11, the tension of the long sheet 31 cannot apply a surface pressure close to the metal endless belt 11, so that air invades from both ends as it is. Therefore, the surface of the long sheet 31 is charged by the charging electrode 51, and the surface is brought into close contact with the reverse charge induced in the metal endless belt 11 by the Coulomb force. The charging electrode 51 is connected to a DC high voltage power supply and a positive voltage is applied. The applied voltage is preferably in the range of 7 kV to 15 kV. As a result, it is possible to suppress the generation of electric discharge between the long sheet 31 and the metal endless belt 11 even when passing through the 24 parts of the plasma. Further, the electric charge applied by the charging electrode 51 is eliminated by the plasma 24.

Next, the above-described embodiment will be described in more detail with reference to Examples and Comparative Examples.
(Examples 1 to 13, Comparative Examples 1 to 12) Next, the above-described embodiments will be described in more detail with reference to Table 1 with reference to Examples and Comparative Examples.
[Common conditions]

In the examples and comparative examples, the liquid crystal polymer film was used as the long sheet 31. As the plasma processing apparatus, the one having the configuration shown in FIG. 1 was used. The sheet width is 100 mm and the length is 30 m. The liquid crystal polymer film 10 used was manufactured by Kuraray Co., Ltd., and had a product number "Vecstar CTS 50 N", a thickness of 50 μm, and a width of 100 mm. The material of the metal endless belt was SUS306L, the thickness was 0.1 mm, the width was 150 mm, the circumference was 200 cm, the length of the flat portion was 80 cm, and the tension was 300 N / m. The tension of the long sheet 31 was set to 200 N / m, and the transport speed was changed in the range of 1 to 20 m / min. Two electrode plates 21 having a width of 120 mm and a length of 100 mm in the transport direction were used side by side in the transport direction. Therefore, the discharge area is 240 cm ² . The gap with the metal endless belt 11 was set to 2 mm. As the discharge gas, a mixed gas of nitrogen 45 L / min having a purity of 5 N and clean air 5 L / min having a purity of 5 N stall −50 ° was used. The plasma generation power was 1 kW. The pressure of the nip roller 4 was only the weight of the roller itself. An HD-R manufactured by Simco was used for the charging electrode, and CM5-30 was used for the DC high voltage power supply.

The treated state of the treated liquid crystal polymer film was evaluated by the contact angle with pure water. For the contact angle, the amount of water droplets was 0.2 mL, and the average value measured at 5 points was used. Wrinkles and deformation were also visually evaluated. The presence or absence of electric discharge on the back surface was determined by spraying water on the back surface of the liquid crystal polymer film with a hand spray and determining the degree of adhesion thereof.
[Example 1]
A process of 5 m was performed with a charging voltage of 10 kV and a transport speed of 5 m / min. The contact angle was 12.3 °. The contact angle of the untreated liquid crystal polymer film was 94.3 °. No particular abnormality was found in the appearance.

[Example 2]
A process of 5 m was performed with a charging voltage of 10 kV and a transport speed of 10 m / min. The contact angle was 38.8 °. No particular abnormality was found in the appearance. No discharge was observed on the back surface.

[Example 3]
A process of 5 m was performed with a charging voltage of 10 kV and a transport speed of 20 m / min. The contact angle was 62.6 °. No particular abnormality was found in the appearance. No discharge was observed on the back surface.

[Comparative Example 1]
The processing was performed at 5 m with a charging voltage of 0 kV and a transport speed of 5 m / min. The contact angle was 13.1 °. As for the appearance, both ends in the film width direction were slightly shrunk. In addition, it was determined that the water droplets were easily wetted within a range of about 5 mm from the end of the back surface, and that an electric discharge was generated.

[Comparative Example 2]
The processing was performed at 5 m with a charging voltage of 0 kV and a transport speed of 10 m / min. The contact angle was 39.2 °. No particular abnormality was found in the appearance. However, it was also determined that the water droplets were easily wet within a range of about 2 cm from the end of the back surface, and that an electric discharge was generated.

[Comparative Example 3]
The processing was performed at 5 m with a charging voltage of 0 kV and a transport speed of 20 m / min. The contact angle was 72.4 °. No particular abnormality was found in the appearance. No discharge was observed on the back surface. However, it was also determined that there was a streak-like wettable portion along the transport direction on the entire back surface, and that discharge was generated.

Although the present invention has been described above in terms of preferred embodiments, such a description is not a limitation, and of course, various modifications can be made.

11 Metal endless belt
12 Holding roller First roller
13 Tension roller 2 Plate type barrier discharge type atmospheric pressure plasma device 21 Electrode plate 22 Dielectric coating 23 High voltage high voltage power supply 24 Plasma 25 Chamber 26 Mixed gas 27 Exhaust device 31 Long sheet 4 Nip roller 5 Charging device 51 Charging electrode 52 DC high voltage Power supply

Claims (3)

A plasma processing apparatus characterized in that a plate-type electrode coated with a dielectric and a metal endless belt forming a parallel gap are used as a pair of electrodes to generate plasma in an atmospheric pressure atmosphere. The plasma processing apparatus according to claim 1, further comprising a charged electrode facing a metal endless belt on the upstream side of a plate-type electrode coated with a dielectric. Using a plasma processing device using a metal endless belt forming a parallel gap with a plate-type electrode coated with a dielectric as a pair of electrodes, a long sheet is accompanied and conveyed on the metal endless belt, and the metal is conveyed. A plasma processing method characterized by continuously plasma-treating the long sheet in a state where the metal endless belt and the long sheet are in close contact with each other by charging the long sheet on the endless belt made of metal. ..

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