WO2002049925A1

WO2002049925A1 - Apparatus for manufacturing dlc-film-coated plastic container, method of manufacturing the same, and method for cleaning inner electrode

Info

Publication number: WO2002049925A1
Application number: PCT/JP2000/009100
Authority: WO
Inventors: Kenichi Hama; Tsuyoshi Kage; Takumi Kobayashi; Tomoyuki Araki
Original assignee: Mitsubishi Shoji Plastics Corporation; Youtec Co., Ltd.
Priority date: 2000-12-21
Filing date: 2000-12-21
Publication date: 2002-06-27
Also published as: AU2001222223A1

Abstract

An apparatus for manufacturing a DLC-film-coated plastic container in which foreign matters adhering to an inner electrode can be removed by cleaning without decomposing the apparatus, a method of manufacturing the same, and a method for cleaning the inner electrode are disclosed. The apparatus (100) is characterized by having an output change-over mechanism (30) capable of connecting an inner electrode (9) to the earth and connecting an outer electrode (3) to a matching box (14) during the formation of a DLC film, and connecting the inner electrode (9) the matching box (14) and connecting the outer electrode (3) to the earth during the cleaning of the inner electrode.

Description

Specification

DLC film-coated plastic container manufacturing device, its manufacturing method, and internal electrode cleaning method

The present invention relates to an apparatus for manufacturing a DLC film coating plastic container provided with a mechanism for removing foreign substances adhering to the surface of an internal electrode at the time of forming a DLC film, a method for manufacturing the same, and a method for cleaning an internal electrode. Background art

As a container for carbonated drinks and high juice drinks, etc., CVD (Chemical Vapor Deposition) is used to deposit a DLC (diamond-like force) film on the inner surface of plastic containers for the purpose of improving gas barrier properties, etc. Japanese Patent Application Laid-Open No. 8-53117 discloses an evaporation apparatus using a plasma CVD method, particularly a plasma CVD method. Also, Japanese Patent Application Laid-Open No. 10-258885 discloses a manufacturing apparatus and a manufacturing method for mass-producing a DLC film-coated plastic container. Furthermore, Japanese Patent Application Laid-Open No. 10-228684 describes a manufacturing apparatus and a manufacturing method capable of coating a DLC film on a container having a protruding object protruding outward from an outer surface. Is disclosed.

The DLC film is a film called an i-carbon film or a hydrogenated amorphous carbon film (a-C: H), and includes a hard carbon film. The DLC film is an amorphous carbon film, and has SP ³ bonds and SP ² bonds.

The apparatus for manufacturing a DLC film-coated plastic container disclosed in Japanese Patent Application Laid-Open No. 8-5311 / 17 has a vacuum chamber, and this vacuum chamber has an external electrode. A space is formed inside this external electrode This space is for storing plastic bottles (PET bottles), which are plastic containers to be coated. The external electrodes are connected to a matching box (impedance matching device), and the matching box is connected to a high-frequency power supply (RF power supply) via a coaxial cable.

An internal electrode is inserted into the space inside the external electrode, and the tip of the internal electrode is a space inside the external electrode and is arranged inside a socket accommodated in the external electrode. The internal electrode has a hollow tubular shape. A gas outlet is provided at the tip of the internal electrode. The base end of the internal electrode is connected to gas introduction means.

The internal electrode is grounded. The space inside the external electrode is open to the atmosphere via a vacuum valve. The space inside the external electrode is connected to a vacuum pump.

Next, a method for forming a DLC film inside a container using the above-described CVD film forming apparatus will be described.

First, a pet bottle is stored in a chamber that is open to the atmosphere. Then, by closing the air release vacuum valve and operating the vacuum pump, the inside of the vacuum chamber including the inside of the pet bottle is evacuated, and the space in the external electrode is evacuated.

Next, the hydrocarbon gas whose flow rate is controlled by using the gas introducing means is blown out from the gas blow-out port through the internal electrode at the ground potential. As a result, hydrocarbon gas is introduced into the pet bottle. Then, the inside of the vacuum chamber and the inside of the head are kept at a pressure suitable for DLC film formation by controlling the gas flow rate and the balance of the exhaust capacity.

After that, the RF output is supplied to the external electrodes from the high frequency power supply via the matching box. As a result, plasma is generated between the external electrode and the internal electrode. At this time, the matching box is matched to the impedance of the external electrode and the internal electrode by the inductance L and the capacitance C. As a result, hydrocarbon-based Plasma is generated, and a DLC film is formed inside the bottle. Next, the output from the high-frequency power supply is stopped, and the supply of the source gas is stopped. Thereafter, the hydrocarbon gas in the vacuum chamber and the pet bottle is exhausted by a vacuum pump. After that, the vacuum chamber is opened to the atmosphere to open the inside of the vacuum chamber to the atmosphere, and the above-described film forming method is repeated to form a DLC film in a plurality of pet bottles. Disclosure of the invention

By the way, in the above-mentioned conventional apparatus for manufacturing a DLC film-coated plastic container, when a DLC film is formed on the inner surface of a PET bottle, the outer surface and inner surface of the internal electrode are also film-like foreign substances containing carbon as a main component (hereinafter, referred to as a foreign material). , "Foreign matter adhering to the internal electrode." For this reason, as the deposition of the DLC film in a plurality of PET bottles is repeated, the thickness of the foreign matter attached to the internal electrode gradually increases. If the film thickness becomes a certain thickness, for example, about 5 m, it will peel off from the internal electrodes. The peeled foreign matter falls into the pet bottle, and as a result, the foreign matter that has fallen in the pet pot forms a portion in the pet pot where a film is not formed, thereby deteriorating the gas barrier property and resulting in a defective product. .

On the other hand, the following methods can be considered to prevent the foreign substances adhering to the internal electrodes from falling into the PET bottle. In other words, before the foreign substances attached to the internal electrodes are peeled off, and after the DLC film has been formed in a certain number of the petroleum, the manufacturing apparatus of the DLC film-coated plastic container is disassembled and disassembled. In this method, the electrode is removed, and the outer surface and inner surface of the internal electrode to which foreign matter is attached are cleaned by a file using an operator. By cleaning the outer and inner surfaces of the internal electrode in this way, it should be possible to prevent foreign substances from falling into the PET bottle.

Using such a method, the internal electrode adheres to the inside of the PET bottle. It is possible to prevent the foreign matter from peeling off. However, this leads to a decrease in the operating rate of the DLC film deposition system in the plastic container.

An object of the present invention is to prevent the thin film adhered to the internal electrode from peeling into the container and to remove foreign substances adhered to the internal electrode without disassembling and cleaning the apparatus, thereby reducing the operation rate. Low DLC film coating plastic container manufacturing device, especially DLC film coating plastic container manufacturing device with cleaning mechanism for removing foreign substances adhering to internal electrodes by plasma discharge, and method of manufacturing the same Another object of the present invention is to provide a method for cleaning an internal electrode.

Further, an object of the present invention is to obtain a sufficient cleaning effect by a cleaning gas by applying a self-bias voltage to the internal electrodes in removing foreign substances attached to the internal electrodes by plasma discharge.

Further, an object of the present invention is to provide a device in which a plurality of combinations of external electrodes and internal electrodes are installed in parallel, and in the case where a plurality of cleanings are performed simultaneously, high-frequency output is concentrated in one or two chambers and discharge is performed only in those chambers. The problem is that a sufficient cleaning effect by the cleaning gas can be obtained in all the champers without causing a phenomenon that the discharge occurs and the other chambers do not discharge. By evenly cleaning, multiple cleanings are performed simultaneously, and it is not necessary to clean one internal electrode at a time, and the purpose is to save cleaning time. By effectively performing these cleanings, it is possible to prevent the thin film adhering to the internal electrodes from peeling into the container and to clean foreign substances adhering to the internal electrodes without disassembling and cleaning the device. As a result, the objective of providing a device with less decrease in the operating rate can be achieved.

The container according to the present invention includes a container used with a lid, a stopper, or a seal, or a container used in an open state without using them. The size of the opening is determined according to the contents. Plastic container Include a plastic container having an appropriate rigidity and a predetermined thickness, and a plastic container formed of a non-rigid sheet material. Also includes a container lid.

Examples of the filling of the plastic container according to the present invention include beverages such as carbonated beverages, fruit beverages, and soft drinks, as well as pharmaceuticals, agricultural chemicals, and dry foods that dislike moisture absorption. In order to solve the above-mentioned problems, a manufacturing apparatus for a DLC film-coated plastic container according to the present invention is an apparatus for forming a DLC film inside a plastic container,

External electrodes arranged so as to surround the vicinity of the outside of the plastic container;

An internal electrode arranged inside the plastic container,

Source gas introduction means for introducing a source gas into the plastic container;

Cleaning gas introducing means for introducing a cleaning gas into the inside of the external electrode for introducing a cleaning gas for removing foreign matter attached to the internal electrode;

When forming the DLC film, the connection between the internal electrode and the ground and the connection between the external electrode and a matching box for impedance matching of the high-frequency load are performed.When the internal electrode is cleaned, the internal electrode is connected to the ground. An output switching mechanism that can be switched mutually so as to be able to connect to the matching box and to connect the external electrode to the ground; and • a high-frequency power supply connected to the matching pox;

It is characterized by having.

It is preferable that the output switching mechanism of the present invention is capable of simultaneously switching the plurality of connections at the time of switching between DLC film formation and internal electrode cleaning.

Further, the DLC film-coated plastic container according to the present invention is manufactured. The manufacturing method is as follows: an internal electrode connected to the ground is arranged inside a plastic container; an external electrode is arranged so as to surround the vicinity of the outside of the plastic container; a raw material gas is supplied into the plastic container; A DLC film forming step of forming a DLC film on the inner surface of the plastic container by generating a plasma of the raw material gas between the internal electrode and the external electrode by supplying a high frequency output to the internal electrode and the external electrode. Multiple times,

In the DLC film forming step, the internal electrode is connected to the ground and the external electrode is connected to a matching box for impedance matching of a high-frequency load. After performing an output switching step of connecting the box and the external electrode and the ground,

A cleaning gas is supplied to the inside of the external electrode from which the plastic container has been removed, a high-frequency output is supplied to the internal electrode, and a plasma is generated between the internal electrode and the external electrode by the assing to generate a plasma by the cleaning gas. A cleaning step for removing foreign matter attached to the internal electrode is performed.

Further, in the internal electrode cleaning method according to the present invention, a grounding is connected to an external electrode which can be arranged so as to surround the vicinity of the outside of the plastic container, and a cleaning gas is provided inside the external electrode with the plastic container removed. And supplying a high-frequency output to an internal electrode disposed inside the external electrode, and attaching to the surface of the internal electrode by asking to generate a plasma by the cleaning gas between the internal electrode and the external electrode. The method is characterized in that foreign matter that has been removed is removed.

In the present invention, since a method of supplying a high-frequency output to the internal electrode instead of the external electrode is employed, stable plasma can be maintained. Also, when multiple chambers are arranged and discharged simultaneously, it is possible to easily supply power to each chamber evenly by installing and adjusting a variable capacitor in each chamber. As a result, power was concentrated in some chambers and only one or two chambers were needed. It does not mean that it does not discharge. Also, in the discharged chamber, the phenomenon that the internal electrodes glow red due to the concentration of power does not occur. The reason that the plasma is stable and that the power supply to the chamber can be equalized is that high-frequency output is supplied to the internal electrode and the external electrode is set to the ground potential. In the device of the present invention, the area of the inner surface of the external electrode is much larger than the outer surface of the internal electrode. In general, in a capacitively coupled high-frequency discharge, the area of the electrode on the high-frequency supply side (usually called the force electrode) is opposite to the area of the electrode (usually called the anode electrode) that is dropped to ground potential. The self-bias voltage generated at the cathode is greatly affected by the size. That is, a negative self-bias voltage is generated at the electrode having a relatively smaller area. Therefore, in the apparatus of the present invention, the anode electrode (external electrode) is larger than the cathode electrode (internal electrode) and a negative self-bias is applied, so that a stable plasma can be generated. It has become. In addition, this enables stable discharge in all chambers even when cleaning a plurality of chambers at the same time.

On the other hand, when the DLC film of the present invention was formed, a stable discharge was obtained despite the fact that the internal electrode was grounded and a high-frequency output was supplied to the external electrode. The reason is that the PET bottle, which is the object of film formation, covers the entire surface of the cathode electrode (the inner surface of the external electrode), and thus it is considered that stable plasma is generated by DC insulation.

In the apparatus for manufacturing a DLC film-coated plastic container according to the present invention, the manufacturing method thereof, and the internal electrode cleaning method, the cleaning gas is oxygen gas, fluorine-based gas, a mixed gas of oxygen gas and rare gas, oxygen gas. It is preferably one gas selected from the group consisting of a mixed gas of fluorine gas and fluorine gas, a mixed gas of fluorine gas and rare gas, and a mixed gas of oxygen gas, fluorine gas and rare gas. Where Examples of the nitrogen-based gas include CH ₂ F ₂ , CF ₄ , and SiF ₆ , and rare gases include argon, helium, krypton, and xenon.

As the raw material gas, hydrocarbon gas and Si-containing hydrocarbon gas are preferable. Particularly, acetylene, propylene, and ethylene are preferred.

Alternatively, a plurality of combinations of external electrodes and internal electrodes may be installed in parallel, and a DLC film may be formed inside a plurality of plastic containers at once. According to the present invention, since a high-frequency output is supplied to the upper electrode and the outer electrode is grounded, a self-bias is applied to the inner electrode, and a sufficient cleaning effect by the cleaning gas is obtained. That is, since the area of the internal electrode was smaller than the area of the external electrode, the self-bias voltage of the internal electrode became negative, and efficient cleaning was performed.

In addition, even when a plurality of combinations of external electrodes and internal electrodes are cleaned at the same time by using a device in which a plurality of combinations of the external electrodes and the internal electrodes are installed in parallel, the distribution of the high-frequency output is equal among the electrodes, and the power is concentrated in one or two chambers. There was no phenomenon that discharge occurred only in that chamber and no discharge occurred in other chambers. There was no chamber where the power to be distributed to each electrode was concentrated and discharged, and there was no heating of the internal electrodes and glowing. Therefore, it is easy to perform multiple cleanings at the same time, and there is no need to clean one internal electrode at a time, saving cleaning time.

Therefore, the foreign matter adhered to the internal electrode can be effectively cleaned, so that the foreign matter was prevented from peeling off into the container, and a decrease in the operation rate of the apparatus could be suppressed.

In addition, cleaning gases such as oxygen gas, fluorine gas, mixed gas of oxygen gas and rare gas, mixed gas of oxygen gas and fluorine gas, mixed gas of fluorine gas and rare gas, and mixed gas of oxygen gas and fluorine gas More effective cleaning was possible by using a mixed gas of a rare gas. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a configuration diagram schematically showing a DLC film forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing the configuration of the output switching mechanism 30 during film formation. FIG. 3 is a diagram showing the configuration of the output switching mechanism 30 during internal electrode cleaning.

The meanings of the symbols shown in FIGS. 1 to 6 are as follows. 1 Lower external electrode, 2 Upper external electrode, 3 External electrode, 4 Insulating material, 5 Lid, 6 Vacuum chamber, 7 Pet bottle, 8 Ring, 9 Internal electrode, 9a Gas outlet, 10, 11, 12,13,23 piping, 14 matching box, 15 high frequency power supply, 16,17,18,24 vacuum valve, 19,25 muff outlet controller, 20 source gas source, 21 vacuum pump, 26 cleaning gas supply source, 27 Leak gas (air) supply source, 28 Vacuum gauge, 29 Exhaust duct, 30 Output switching mechanism, 31 Wiring to external electrode, 32 Wiring to internal electrode, 33 Wiring to matching box, 34 Wiring to ground, 37 relay, 41 source gas introduction means, 42 cleaning gas introduction means, 100 DLC membrane coating plastic container manufacturing equipment. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described with reference to FIG. An apparatus for manufacturing a DLC film-coated plastic container according to an embodiment of the present invention is an apparatus for forming a DLC film or a Si-containing DLC film inside a container or the like by using a plasma CVD method. The present invention is not limited to the embodiments described below, and can be appropriately modified within the range in which the effects of the present invention are exhibited.

FIG. 1 is a configuration diagram schematically showing an apparatus 100 for manufacturing a DLC film-coated plastic container according to an embodiment of the present invention.

The apparatus 100 for manufacturing a DLC film-coated plastic container according to the present invention includes an external electrode 3, an internal electrode 9, a source gas introducing means 41, A matching box 14, a high-frequency power supply 15, a cleaning gas introducing means 42 for introducing a cleaning gas for removing foreign substances attached to the internal electrode 9 into the inside of the external electrode 3, and an internal electrode for forming a DLC film. An output switching mechanism 30 is provided which can switch between connection to the ground and connection between the external electrode and the matching box to connection between the internal electrode and the matching box and connection between the external electrode and the ground during internal electrode cleaning. .

The external electrode 3 forms a vacuum chamber 6 together with the conductive lid 5 and the insulating member 4. An insulating member 4 is disposed below the lid 5, and an external electrode portion 3 is disposed below the insulating member 4. The external electrode 3 is composed of an upper external electrode 2 and a lower external electrode 1, and is configured such that the upper part of the lower external electrode 1 is detachably attached to the lower part of the upper external electrode 2 via an O-ring 8. . The external electrode 3 is insulated from the lid 5 by the insulating member 4.

In this embodiment, the external electrode 3 is divided into a lower external electrode 1 and an upper external electrode 2, but in order to make the thickness of the DLC film uniform, the external electrode is, for example, a bottom electrode. , Divided into three or more, such as a torso electrode and a shoulder electrode, and each electrode is electrically insulated with a Teflon sheet or polyimide film while ensuring sealing properties with a ring, etc. You may.

A space is formed inside the external electrode 3 for accommodating a plastic container to be coated, for example, a PET bottle 7 molded of polyethylene terephthalate resin. It is. The space inside the external electrode 3 is formed to be slightly larger than the outer shape of the socket 7 accommodated therein. The insulating member 4 and the lid 5 are provided with openings that connect to the space inside the external electrode 3. Further, a space is provided inside the lid portion 5, and this space is connected to the space inside the external electrode 3 via the opening. The space inside the external electrode 3 is the upper external electrode 2 It is hermetically sealed from the outside by a ring 8 arranged between the lower electrode 1 and the lower electrode.

The lower outer electrode 1 of the outer electrode 3 is grounded via an output switching mechanism 30 or connected to a matching box 14, and the matching box 14 is connected to a high frequency power supply 15 via a coaxial cable. Have been.

The internal electrode 9 is arranged inside the external electrode section 3 and inside the pet bottle 7. That is, the internal electrode 9 is inserted into the space inside the external electrode 3 from the upper part of the lid 5 through the space in the lid 5 and the opening of the lid 5 and the insulating member 4. That is, the base end of the internal electrode 9 is arranged above the lid 5, and the tip 9 a of the internal electrode 9 is arranged in the space inside the external electrode 3 and inside the PET bottle 7 housed inside the external electrode 3. Is placed. The internal electrode 9 has a hollow tubular shape. At the tip of the internal electrode 9, a gas outlet 9a is provided.

The source gas introducing means 41 introduces the source gas supplied from the source gas source 20 into the PET bottle 7. That is, one end of the pipe 10 is connected to the base end of the internal electrode 9, the other side of the pipe 10 is connected to one side of the pipe 11, and the other side of the pipe 11 is connected via the vacuum valve 16. It is connected to one side of the masochist controller 19. The other side of the mass flow controller 19 is connected to a source gas generation source 20. The source gas generating source 20 generates a hydrocarbon gas such as acetylene.

The cleaning gas introducing means 42 supplies the cleaning gas supplied from the cleaning gas supply source 26 to the inside of the external electrode 3. That is, one side of the pipe 23 is connected to the pipe 10, and the other side of the pipe 23 is connected to one side of the mass flow controller 25 via the vacuum valve 24. The other side of the mass flow controller 25 is connected to a cleaning gas supply source 26 such as an oxygen cylinder. Have been. The cleaning gas supply source 26, the mass flow controller 125, the vacuum valve 24 and the like function as a cleaning mechanism. The internal electrode 9 is grounded via an output switching mechanism 30, or is connected to a matching box 14, and the matching box 14 is connected to a high frequency power supply 15 via a coaxial cable.

The output switching mechanism 30 will be described with reference to FIGS. FIG. 2 shows the configuration of the output switching mechanism 30 during film formation, and FIG. 3 shows the configuration of the output switching mechanism 30 during internal electrode cleaning. That is, the connection combinations of the wiring 32 to the internal electrode 9, the wiring 31 to the external electrode 3, the wiring 33 to the matching box 14, and the wiring 34 to the ground can be switched by the relay 37. I have. During film formation, the wiring 32 to the internal electrode is connected to the wiring 34 to the ground via the relay 37, and the wiring 31 to the external electrode 3 is connected to the wiring 33 to the matching box 14 (FIG. 2). When cleaning the internal electrode, the wiring 32 to the internal electrode 9 via the relay 37 is connected to the wiring 33 to the matching box 14, and the wiring 31 to the external electrode 3 is connected to the wiring 34 to the ground (Fig. 3).

The space inside the lid is connected to one side of a pipe 12, and the other side of the pipe 12 is opened to the atmosphere via a vacuum valve 17. The space in the lid is connected to one side of a pipe 13, and the other side of the pipe 13 is connected to a vacuum pump 21 via a vacuum valve 18. This vacuum pump 21 is connected to an exhaust duct 29. A vacuum gauge 28 is installed in the pipe 13. Next, a method for forming a DLC film inside a container using the DLC film-coated plastic container manufacturing apparatus 100 shown in FIG. 1 will be described.

First, the vacuum valve 17 is opened to open the inside of the vacuum chamber 16 to the atmosphere. As a result, air passes through the pipe 12 and the space inside the lid 5 and the external electrodes 3 Then, the inside of the vacuum chamber is brought to atmospheric pressure. Next, the lower external electrode 1 is detached from the upper external electrode 2, and a pet bottle 7 is inserted into the space inside the upper external electrode 2 and installed. At this time, the internal electrode 9 is in a state of being inserted into the pet bottle 7. Next, the lower external electrode 1 is attached to the lower part of the upper external electrode 2, and the external electrode 3 is sealed by the ring 8.

Then, after closing the vacuum valve 17, the vacuum valve 18 is opened and the vacuum pump 21 is operated. As a result, the inside of the vacuum chamber (the space in the external electrode 3 and the lid, the space in 5) including the inside of the PET bottle 7 is exhausted through the pipe 13, and the inside of the external electrode 3 is evacuated. At this time, the pressure in the vacuum chamber 16 is a pressure sufficiently lower than that at the time of film formation, for example, 5.0 × 10 ″ ³ to 1.0xlO — ¹ Torr.

Next, the vacuum valve 16 is opened, acetylene gas is generated in the source gas source 20, and the flow rate of the acetylene gas is controlled by the mass flow port controller 19, and the pipe 10 and the output switching mechanism are controlled via the pipe 11. The gas is blown out from the gas blowout port 9a through the internal electrode 9 which is set to the ground potential by 30. As a result, acetylene gas is introduced into the pet bottle 7. Then, the pressure inside the vacuum chamber 16 and the inside of the pet bottle 7 are kept at a pressure suitable for DLC film formation, for example, about 0.05 to 0.50 Torr, by the balance between the controlled gas flow rate and the exhaust capacity.

Thereafter, an RF output (for example, 13.56 MHz) is supplied from the high-frequency power supply 15 via the matching box 14 connected to the external electrode 3 by the output switching mechanism 30. The high frequency output can be, for example, 300-3000W. As a result, plasma occurs between the external electrode 3 and the internal electrode 9. At this time, the matching box 14 matches the impedance of the external electrode and the internal electrode with the inductance L and the capacitance C. As a result, acetylene-based plasma is generated in the PET bottle 7, and a DLC film is formed inside the PET bottle 7. Filmed. The film formation time at this time is as short as about several seconds.

Next, the HF output from the RF power supply 15 is stopped, the vacuum pulp 16 is closed, and the supply of the source gas is stopped. Thereafter, the vacuum valve 18 is opened, and the acetylene gas in the vacuum chamber 1 and the PET bottle Ί is exhausted by the vacuum pump 21. Then, the vacuum valve 18 is closed. Degree of vacuum in the vacuum chamber within a time this is, for example, ^{5 X 10- 3 ~ 5 X 10-} 2 Torr. Thereafter, the vacuum valve 17 is opened to open the inside of the vacuum chamber 16 to the atmosphere, and the above-described film forming method is repeated, whereby a DLC film is formed in a plurality of sockets.

After a predetermined number of film-forming steps (for example, 10 times) by the method described above, foreign substances adhering to the surface of the internal electrode 9 are removed by asking using a cleaning mechanism. Thereafter, the process of forming the DLC film in the pet bottle by the method described above is restarted.

Next, a specific method of the above-described asshing will be described. After removing the pet bottle 7 from the vacuum chamber 6, the lower external electrode 1 is attached to the upper external electrode 2 in a state where the pet bottle is not stored, and the inside of the external electrode 3 is hermetically sealed by the 0 ring 8. As a result, the space in the external electrode 3 is in a state where nothing is inserted.

Next, by operating the vacuum pump 21, the inside of the vacuum chamber 6 (the space in the external electrode and the space in the lid) is evacuated, and the inside of the vacuum chamber 6 is evacuated. Next, the vacuum valve 24 is opened, and the flow rate of the cleaning gas, for example, oxygen gas supplied from the cleaning gas supply source 26 is controlled by the mass flow controller 25. Then, the oxygen gas whose flow rate is controlled is blown out from the gas blowout port 9a through the internal electrodes 9 connected to the matching box 14 by the pipes 23, 10 and the output switching mechanism 30. As a result, oxygen gas is introduced into the vacuum chamber. The inside of the vacuum chamber 6 is maintained at a pressure suitable for assuring, for example, 0.1 to 10 O Torr by a balance between the controlled oxygen gas flow rate and the exhaust capacity. High frequency output is, for example, 100 to 3000 W.

Thereafter, an RF output is supplied from an RF power supply 15 via a matching box 14 connected to the internal electrode 9 by an output switching mechanism 30. As a result, plasma is generated between the external electrode 3 and the internal electrode 9 grounded by the output switching mechanism 30, and oxygen gas plasma is generated. At this time, the foreign matter adhering to the internal electrode is a film composed of carbon, hydrogen, and the like, and is decomposed and removed from the internal electrode surface by an oxidation reaction using oxygen plasma. If the hydrocarbon film is represented by C nH m in the chemical formula, the oxidation reaction proceeds according to formula 1.

C nH m + (n + m / 4) 0 ₂ → n CO ₂ + (m / 2) H ₂₀ (Equation 1)

Next, the RF output from the RF power supply 15 is stopped, and the supply of the cleaning gas is stopped by closing the vacuum valve 24. Next, the vacuum valve 18 is opened, and O ₂ , CO ₂ , and H ₂ O in the vacuum chamber 16 are evacuated by the vacuum pump 21.

In the present invention, since a high-frequency output was supplied to the internal electrode 9 and the external electrode 3 was grounded, a self-bias was applied to the internal electrode, and a sufficient cleaning effect by oxygen plasma was obtained. That is, since the area of the internal electrode is small with respect to the area of the external electrode, the self-bias voltage of the internal electrode becomes negative, and efficient oxygen cleaning is performed.

In addition, even when cleaning is performed simultaneously on a plurality of combinations of external electrodes and internal electrodes, the distribution of high-frequency output is equal between the electrodes, and power is concentrated in one or two chambers. There was no phenomenon that discharge occurred only in the chamber and no discharge occurred in the other chambers. Since there was no chamber that discharged the power to be distributed to each electrode in a concentrated manner, the internal electrodes did not heat up and glowed red. This makes it easy to perform multiple cleanings at the same time, eliminating the need to clean one internal electrode at a time and saving cleaning time.

According to the above embodiment, the DLC film-coated plastic container Oxygen gas cleaning is performed after a DLC film is formed a predetermined number of times by disposing a cleaning mechanism in the container manufacturing equipment to prevent foreign substances from adhering to the internal electrodes and coming off in the bottle. be able to. Therefore, unlike the conventional DLC film-coated plastic container manufacturing apparatus, the DLC film that has fallen into the bottle does not cause the bottle to become defective.

In addition, since an oxygen gas cleaning mechanism is installed in the DLC film-coated plastic container manufacturing equipment, it adhered to the internal electrodes without disassembling the equipment as in the conventional DLC film-coated plastic container manufacturing equipment. The DLC film can be removed by assing. Therefore, in the conventional DLC film-coated plastic container manufacturing equipment, it took one day to clean the internal electrodes, but the time required for the cleaning can be greatly reduced. As a result of a specific experiment, foreign substances adhering to the surface of the internal electrode could be peeled off cleanly by performing oxygen gas cleaning for the same time as DLC film formation after performing DLC film formation 10 times.

In the above embodiment, oxygen is used as the cleaning gas, but the cleaning gas is not limited to oxygen gas, and any other gas having a cleaning action may be used. For example, fluorine gas, mixed gas of oxygen gas and rare gas, mixed gas of oxygen gas and fluorine gas, mixed gas of fluorine gas and rare gas, oxygen gas, fluorine gas and rare gas And the like. Here, examples of the fluorine-based gas include, for example, CH ₂ F ₂ , CF ₄ , and SiF _6, and examples of the rare gas include argon, helium, krypton, and xenon.

That is, by using the cleaning gas exemplified above, it is possible to effectively ashes foreign substances attached to the internal electrodes.

In addition, the present invention is not limited to the above-described embodiment, and may be implemented with various modifications. It is possible to For example, the source gas source is not limited to a hydrocarbon gas source, and various sources can be used. For example, a Si-containing hydrocarbon gas or the like can be used. Further, in the present embodiment, a pet bottle for beverage is used as a container for forming a thin film inside, but a container used for other purposes may be used.

In this embodiment, a DLC film or a Si-containing DLC film is described as a thin film to be formed. However, when forming another thin film in a container, the DLC film coating plastic according to the present invention is used. It is also possible to use container manufacturing.

Claims

The scope of the claims

In an apparatus that forms a DLC (diamond-like force) film inside a plastic container,

An internal electrode arranged inside the plastic container,

A cleaning gas introducing means for introducing a cleaning gas into the inside of the external electrode for removing a foreign substance attached to the internal electrode by asking;

When forming the DLC film, the connection between the internal electrode and the ground and the connection between the external electrode and a matching box for impedance matching of the high-frequency load are performed.When the internal electrode is cleaned, the internal electrode is connected to the ground. An output switching mechanism that is mutually switchable so that connection with the matching box and connection between the external electrode and the ground can be performed;

A high-frequency power supply connected to the matching box;

An apparatus for producing a DLC film-coated plastic container, comprising:

The cleaning gas includes oxygen gas, fluorine gas, mixed gas of oxygen gas and rare gas, mixed gas of oxygen gas and fluorine gas, mixed gas of fluorine gas and rare gas, and mixed gas of oxygen gas and fluorine gas. 2. The apparatus for producing a DLC film-coated plastic container according to claim 1, wherein the gas is one gas selected from the group consisting of a mixed gas of a rare gas.

An internal electrode connected to the ground is arranged inside the plastic container, an external electrode is arranged so as to surround the outside of the plastic container, a raw material gas is supplied into the plastic container, and a high frequency is applied to the external electrode. Supplying a power, and generating plasma by the raw material gas between the internal electrode and the external electrode to form a DLC film on the inner surface of the plastic container once or more than once in a DLC film forming process Do,

In the DLC film forming step, the internal electrode is connected to the ground, and the external electrode is connected to a matching box for impedance matching of a high-frequency load. After performing an output switching process of connecting the box and the external electrode and the ground,

A cleaning gas is supplied to the inside of the external electrode from which the plastic container is removed, a high-frequency output is supplied to the internal electrode, and an ashes for generating a plasma by the cleaning gas between the internal electrode and the external electrode. A method for producing a DLC film-coated plastic container, comprising: performing a cleaning step of removing foreign substances adhered to the internal electrode by the method.

4. The cleaning gas is oxygen gas, fluorine gas, mixed gas of oxygen gas and rare gas, mixed gas of oxygen gas and fluorine gas, mixed gas of fluorine gas and rare gas, oxygen gas and fluorine gas. 4. The method for producing a DLC film-coated plastic container according to claim 3, wherein the gas is one gas selected from the group consisting of a mixed gas of a gas and a rare gas.

5. Grounding is connected to an external electrode that can be arranged so as to surround the vicinity of the outside of the plastic container, and a cleaning gas is supplied to the inside of the external electrode with the plastic container removed. A high-frequency output gas is supplied to an internal electrode disposed inside, and foreign matter adhered to the surface of the internal electrode is removed by asking for generating a plasma by the cleaning gas between the internal electrode and the external electrode. Characteristic internal electrode cleaning method.

6. The cleaning gas includes oxygen gas, fluorine gas, mixed gas of oxygen gas and rare gas, mixed gas of oxygen gas and fluorine gas, and fluorine gas. 6. The internal electrode cleaning method according to claim 5, wherein the gas is one selected from the group consisting of a mixed gas of an elemental gas and a rare gas, and a mixed gas of an oxygen gas, a fluorine-based gas, and a rare gas.