JP2006299332A - Plasma cvd film deposition apparatus, and method of manufacturing plastic container having barrier property - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress generation of plasma in a gap space (1) without preparing any external electrode for each container having different shape and (2) without providing any pressure difference control mechanism between an inner space and an outer space of the container even by any system of the induction-coupling type plasma or the microwave plasma when performing the film deposition on an inner wall surface of a plastic container. <P>SOLUTION: The plasma CVD film deposition apparatus comprises a vacuum chamber to store a plastic container, a spacer consisting of an insulator arranged in a gap space held between an inner wall surface of the vacuum chamber and an outer wall surface of the plastic container, a raw material gas feed pipe which is attachably/detachably arranged inside the plastic container to feed the raw material gas into the plastic container, an exhaust means to exhaust the gas inside the vacuum chamber, and a plasma generation means to convert the raw material gas fed inside the plastic container into plasma. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a plasma CVD (chemical vapor deposition) film forming apparatus for forming a gas barrier film on an inner wall surface of a plastic container and a method for producing a barrier plastic container.

  The plastic container easily absorbs odors and has a gas barrier property that is inferior to that of bottles and cans, so it has been difficult to use it for carbonated beverages such as beer and sparkling liquor. Accordingly, a method and apparatus for coating a hard carbon film (such as diamond-like carbon (DLC)) have been disclosed in order to solve the problems of sorption and gas barrier properties in plastic containers. Among them, for example, an external electrode having an internal space that is almost similar to the outer shape of the target container, and an internal electrode that is inserted into the inside of the container from the mouth of the container and also serves as a source gas introduction pipe, An apparatus for coating a wall surface with a hard carbon film is disclosed (for example, see Patent Document 1 or 2). In such an apparatus, a high frequency voltage is applied to the external electrode in a state where acetylene gas is supplied as a source gas into the container. At this time, the source gas is turned into plasma by the high-frequency power generated between both electrodes, and the ions in the generated plasma are attracted by the high-frequency potential difference (self-bias) of the external electrode and collide with the inner wall of the container to form a film. Is done.

  There is also a technique of an apparatus for forming a DLC thin film on the surface of a plastic container using inductively coupled plasma (see, for example, Patent Document 3). In general, when inductively coupled plasma is used, the plasma density is higher by one digit or more than the capacitively coupled plasma density, so that there is an advantage that the deposition rate of the thin film is improved and the film formation time can be shortened.

  There is also a technique for forming a thin film on a wall surface of a container by supplying a raw material gas into a space inside or outside the container and supplying a microwave to the raw material gas (see, for example, Patent Document 4).

Japanese Patent No. 2788412 Japanese Patent No. 3072269 WO 03 / 016149A1 Special table 2002-509845 gazette

  However, in the technique described in Patent Document 1 or 2, since an external electrode having an internal space that is substantially similar to the outer shape of the target container must be formed, a plurality of external electrodes corresponding to each shape of the container This has led to an increase in the cost of the film forming apparatus.

  On the other hand, in the technique described in Patent Document 3 or 4, it is not necessary to form an external electrode having an internal space that is substantially similar to the outer shape of the target container. However, when film formation is performed on a small container using a large chamber so that the largest container among the desired containers can be accommodated, a gap space is formed between the inner wall surface of the chamber and the outer wall surface of the container. Is done. For example, when film formation is performed on the inner wall surface of a container, plasma is generated in the gap space, and unintended film formation or plasma etching is performed on the outer wall surface of the container. May not be done on the wall.

  In the technique of Patent Document 4, in order to prevent such unintended plasma generation, a pressure difference is provided between the internal space and the external space of the container to suppress unintended plasma generation. For example, when forming a film on the inner wall surface of the container, the inside of the container should be 0.01 to 0.5 mbar (1 to 50 Pa), the outside of the container should be 50 mbar (5000 Pa), and the outside should be at a relatively high pressure. This suppresses plasma generation.

However, when a pressure difference is provided between the internal space and the external space of the container, if the pressure difference is 10 ⁴ Pa or more, the plastic container is recessed, so that no more pressure difference can be provided. In addition, a perfect seal between the internal space and the external space is required at the mouth of the container. Furthermore, different pressure controls are required, which complicates the film forming apparatus.

  Accordingly, the object of the present invention is to (1) eliminate the need to prepare an external electrode for each container having a different shape when forming a film on the inner wall surface of a plastic container, and (2) inductively coupled plasma or microwave plasma. In any of these methods, a plasma CVD film forming apparatus and a barrier plastic that can suppress the generation of plasma in the gap space without providing a pressure difference control mechanism between the internal space and the external space of the container It is to provide a method for manufacturing a container.

  The inventors of the present invention have found that the generation of plasma in the gap space can be extremely suppressed in the container by occupying the gap space with a spacer (discharge prevention material) made of an insulator, and completed the present invention. That is, the plasma CVD film-forming apparatus according to the present invention comprises a vacuum chamber that houses a plastic container, and an insulator disposed in a gap space sandwiched between the inner wall surface of the vacuum chamber and the outer wall surface of the plastic container. A spacer, a material gas supply pipe for supplying a raw material gas to the plastic container, removably disposed inside the plastic container, an exhaust means for exhausting the internal gas of the vacuum chamber, and an inside of the plastic container Plasma generating means for converting the supplied source gas into plasma.

  In the plasma CVD film forming apparatus according to the present invention, it is preferable that the plastic container is disposed so that a bottom of the plastic container and an inner bottom of the vacuum chamber are in contact with each other. When the bottom of the container and the inner bottom of the vacuum chamber are brought into contact with each other, the portion becomes an opening of the insulator, which can be easily formed. Further, when the plasma is generated by microwave plasma, the microwave can be supplied from the bottom of the container through the opening of the insulator.

  In the plasma CVD film forming apparatus according to the present invention, the plasma generating means has a conductor spirally wound along the side wall of the vacuum chamber and a high-frequency power source for applying high-frequency power to the conductor. And the case where the said source gas is made into plasma by the inductive coupling system is included.

  In the plasma CVD film forming apparatus according to the present invention, the plasma generating means includes a case where the source gas is turned into plasma by supplying a microwave to the source gas.

  In the plasma CVD film forming apparatus according to the present invention, it is preferable that the spacer is formed so as to be divisible by the longitudinally divided surface of the plastic container. Even when the shape of the container is, for example, a shape constricted at the trunk, the spacers can be arranged without gaps.

  In the plasma CVD film forming apparatus according to the present invention, the spacer is preferably made of a resin having a heat resistance with a continuous use temperature of 100 ° C. or higher and a water absorption of 0.30% or less. Except for suppressing the generation of plasma in the gap space, it is possible to suppress the spacer from participating in the reaction system.

  In the plasma CVD film forming apparatus according to the present invention, the spacer is formed from at least one of fluororesin, silicon resin, polyimide, polyamideimide, polyphenylene sulfide, polymethylpentene, cyclic olefin copolymer, or polyether ether ketone. It is preferable that

  In the plasma CVD film forming apparatus according to the present invention, the spacer has a maximum gap between the wall surface of the spacer and the inner wall surface of the vacuum chamber or a maximum gap between the wall surface of the spacer and the outer wall surface of the plastic container of 20 mm or less. It is preferable to have a shape.

  The manufacturing method of the barrier plastic container according to the present invention includes a spacer made of an insulator for occupying a gap between a plastic container and an inner wall surface of the vacuum chamber and an outer wall surface of the plastic container. A step of evacuating the internal gas of the vacuum chamber, a step of supplying a raw material gas into the plastic container, and generating a raw material gas plasma only in the internal space of the plastic container, Forming a gas barrier thin film on the inner wall surface of the plastic container.

  In the method for manufacturing a barrier plastic container according to the present invention, it is preferable that the plastic container is disposed in the vacuum chamber so that the bottom of the plastic container and the inner bottom of the vacuum chamber are in contact with each other. The container and the spacer can be easily mounted in the vacuum chamber.

  In the method for producing a barrier plastic container according to the present invention, it is preferable that the source gas is plasmatized by an inductive coupling method or plasmatized by a microwave.

In the method for producing a barrier plastic container according to the present invention, it is preferable to form a carbon film, a silicon-containing carbon film, or a SiO _x film as the gas barrier thin film.

  In the present invention, when forming a film on the inner wall surface of a plastic container, it is not necessary to prepare an external electrode for each container having a different shape, and the container can be formed by any method of inductively coupled plasma or microwave plasma. It is possible to suppress the generation of plasma in the gap space without providing a pressure difference control mechanism between the internal space and the external space.

  Hereinafter, the present invention will be described in detail with reference to embodiments, but the present invention is not construed as being limited to these descriptions. A plasma CVD film forming apparatus according to this embodiment will be described with reference to FIGS. In addition, the same code | symbol was attached | subjected to the common site | part and components.

(First embodiment: CVD film forming apparatus using inductively coupled plasma)
FIG. 1 is a schematic configuration diagram showing an embodiment of a plasma CVD film forming apparatus according to the present embodiment. 1, the vacuum chamber 5 is a schematic cross-sectional view in the vertical direction of the container. As shown in FIG. 1, a plasma CVD film forming apparatus 100 according to this embodiment includes a vacuum chamber 5 that houses a plastic container 7, and a gap space that is sandwiched between an inner wall surface of the vacuum chamber 5 and an outer wall surface of the plastic container 7. 10, a spacer 20 made of an insulator, a raw material gas supply pipe 9 which is disposed in the plastic container 7 so as to be insertable / removable, and which supplies a raw material gas to the plastic container 7, and an internal gas of the vacuum chamber 5 is exhausted. And a plasma generating means for converting the raw material gas supplied into the plastic container 7 into plasma.

  The plasma generating means according to the first embodiment includes a conductor 21 spirally wound along the side wall of the container housing part 1 formed of an insulator, and a high-frequency power source 13 that applies high-frequency power to the conductor 21. And a plasma CVD film forming apparatus that converts the source gas into plasma by an inductive coupling method.

  The vacuum chamber 5 has an opening 6 for taking in and out the plastic container 7, and the container accommodating part 1 that completely accommodates the plastic container 7 from the bottom to the mouth and the peripheral end of the opening 6 are fixed in an airtight state. And a lid 3 disposed on the fixed portion 2 and supporting the source gas supply pipe 9. In the vacuum chamber 5, these members are assembled and hermetically sealed.

  The fixing portion 2 has a circular hole that penetrates with an inner diameter that is slightly larger than the inner diameter of the internal space of the container housing portion 1, and the annular recess 4 according to the shape of the peripheral end of the opening 6 of the container housing portion 1. The lower fixing portion 2a provided with the upper fixing portion 2b that sandwiches the peripheral end of the opening 6 of the container housing portion 1 together with the lower fixing portion 2a. A resin seal member 8 having airtightness and cushioning properties is disposed at a contact portion between the lower fixing portion 2a and the peripheral end of the opening 6.

  On the inner surface side of the lid 3, a first circular recess 23 having a diameter substantially the same as that of the circular hole of the fixing portion 2 and a second circular recess 24 having a small diameter are provided by the bottom of the first circular recess 23. An exhaust passage 31 is provided inside the lid 3, and one end of the exhaust passage 31 opens at the side surface of the second circular recess 24. The other end of the exhaust passage 31 is connected to the exhaust means 19.

  The internal space of the container housing portion 1, the space formed by the circular hole of the fixed portion 2, the space formed by the first circular concave portion 23, and the space formed by the second circular concave portion 24 form the internal space 22 of the vacuum chamber 5. Will be formed.

  The container housing portion 1 is formed of an insulator, for example, quartz glass or ceramics such as alumina, in order to be electrically insulated from the high-frequency power flowing through the conductor 21. The fixing portion 2 and the lid portion 3 may be formed of a conductive material or an insulating material. Since it preferably has rigidity, it is preferably formed of a metal such as stainless steel or an alloy.

  The conductor 21 is preferably formed of a highly conductive metal such as copper or an alloy, and the cross-sectional shape of the conductor 21 may be any of a circle, an ellipse, and a rectangle. The number of turns of the conductor 21 is appropriately determined depending on the height of the container housing 1 and the inner diameter thereof. A high frequency power source 13 is connected to one end of the conductor 21 via the matching box 12. The other end of the conductor 21 is grounded.

  The conductor 21 may be wound spirally along the side wall of the container housing portion 1, and may be wound on the outer wall side or the inner wall side of the container housing portion 1. Or you may arrange | position inside the container accommodating part 1. FIG. As shown in FIG. 1, when the cross-sectional shape of the conductor 21 is circular, the conductor 21 is wound spirally to form a coil.

  The spacer 20 is configured to be divided by a lower spacer 20b and an upper spacer 20a. FIG. 2 is an example of the shape of a spacer for a square plastic container, (a) is a longitudinal sectional view of the upper spacer, (b) is a view of the upper spacer as viewed from below (direction A), and (c) is a lower spacer. A longitudinal sectional view, (d) shows a view of the lower spacer as viewed from below (B direction). 3 is an example of the shape of a spacer for a round plastic container, (a) is a longitudinal sectional view of the upper spacer, (b) is a view of the upper spacer as viewed from below (C direction), and (c) is a lower portion. The vertical cross-sectional view of the spacer, (d) shows a view of the lower spacer as viewed from below (D direction). 2 or 3 shows a case where the internal space 22 of the vacuum chamber 5 has a cylindrical shape. However, regardless of the shape of the internal space 22, the shape of the spacer can be changed as shown in FIG. As described above, the gap space 10 sandwiched between the inner wall surface of the vacuum chamber 5 and the outer wall surface of the plastic container 7 can be almost occupied by the spacer. Without the spacer 20, the maximum gap d between the spacer wall surface and the inner wall surface of the vacuum chamber or the maximum gap d between the spacer wall surface and the outer wall surface of the plastic container is larger than the mean free path λ of ionization of the source gas molecules. In many cases, plasma is generated because impact ionization occurs in the gap space 10. Then, the DLC film is not formed on the inner wall surface of the plastic container 7. In order to prevent this, the spacer 20 is inserted so that d is approximately 3λ or less. Thereby, it is possible to easily suppress the generation of plasma outside the container without providing a mechanism for controlling the pressure difference inside and outside the container inside the vacuum chamber 5. In addition, the upper spacer 20a is provided with a recess so that the gas remaining in the gap space 10 is easily exhausted, and a gas flow path 32 is formed. FIG. 2 or FIG. 3 shows a shape corresponding to a barrel-shaped plastic container having no waist in the body, but in a plastic container having a neck in the body, the upper spacer 20a and the lower spacer 20b are respectively made of plastic containers. It may be formed so as to be divisible by 7 vertical dividing surfaces (not shown). 2 or 3 shows an example in which the upper spacer 20a and the lower spacer 20b are divided into two, but it may be divided into three or more.

  The through hole 26 provided in the upper spacer 20 a forms a part of a flow path for exhausting internal gas from the mouth of the plastic container 7. The lower spacer 20b is formed so as to be substantially in contact with the wall surface of the shoulder portion from the trunk portion of the plastic container 7 to prevent plasma generation. In addition, an opening 28 is provided in the lower part of the lower spacer 20b, and the opening 28 can be disposed so that the bottom of the plastic container 7 and the inner bottom of the vacuum chamber 5 are in contact with each other as shown in FIG. . Here, when a plurality of types of plastic containers 7 having different capacities and shapes are formed by the same CVD film forming apparatus, the height of the container varies depending on the type of the container. However, if the bottom of the plastic container 7 and the inner bottom of the vacuum chamber 5 are in contact with each other, the position of the bottom of the plastic container 7 can always be constant regardless of the height of the plastic container 7, Therefore, the relative positional relationship with the conductor 21 can be made constant. Moreover, since the plastic container 7 can be inserted from the opening 28 of the lower spacer 20b, mounting becomes easy.

  The spacer 20 is formed of an insulator, but is preferably formed of a resin having a heat resistance with a continuous use temperature of 100 ° C. or higher and a water absorption of 0.30% or less. You may form with a quartz glass body. The spacer 20 may be either a foam or a dense body, but is preferably a dense body from the viewpoint of making it difficult to release moisture during decompression. An insulator refers to a material having a sufficiently small electrical conductivity or thermal conductivity, and the electrical insulator is considered synonymous with a dielectric. Since energy is lost as heat when an AC electric field is applied to a dielectric, a material with a low dielectric loss coefficient is selected when selecting a dielectric material. Specifically, it is preferably formed from at least one of fluororesin, silicon resin, polyimide, polyamideimide, polyphenylene sulfide, polymethylpentene, cyclic olefin copolymer or polyether ether ketone. Polymethylpentene and the cyclic olefin copolymer are transparent resins, and visual observation of plasma emission in the gap space becomes easy. The spacer 20 may be formed of a combination of a plurality of resins. For example, the upper spacer may be formed of a fluororesin and the lower spacer may be formed of polyimide. Here, a fluororesin having a small dielectric constant and dielectric loss coefficient is selected. For example, PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), ETFE (tetrafluoroethylene-ethylene copolymer), There are ECTFE (chlorotrifluoroethylene-ethylene copolymer) and PFEP (tetrafluoroethylene-hexafluoropropylene copolymer). Although the workability is inferior, the spacer may be formed of ceramics.

  It is preferable to form the spacer 20 so that the maximum gap between the wall surface of the spacer 20 and the inner wall surface of the vacuum chamber 5 or the maximum gap between the wall surface of the spacer 20 and the outer wall surface of the plastic container 7 is 20 mm or less. The maximum gap is appropriately adjusted according to the pressure in the vacuum chamber 5. The guidelines are as follows. Under the condition that the pressure in the vacuum chamber 5 is 6.7 Pa or more, the generation of plasma can be suppressed by setting the maximum interval to 20 mm or less. Furthermore, plasma generation can be suppressed by setting the maximum interval to 10 mm or less under the condition where the pressure in the vacuum chamber 5 is 13.3 Pa or more. Under the condition where the pressure in the vacuum chamber 5 is 26.6 Pa or more, the generation of plasma can be suppressed by setting the maximum interval to 5 mm or less. FIG. 5 shows the relationship between the maximum gap and the upper limit pressure of the vacuum chamber that does not discharge in the gap space. It is preferable to form the film at a pressure equal to or lower than the upper limit pressure corresponding to the maximum gap.

  A source gas is supplied to the source gas supply pipe 9 from a source gas supply means 14 including a source gas generation source 16 and a mass flow controller 15. That is, one end of the pipe 29 is connected to one end of the source gas supply pipe 9, and the other side of the pipe 29 is connected to one side of the mass flow controller 15 via the vacuum valve 30. The other side of the mass flow controller 15 is connected to the source gas generation source 16 via a pipe. The source gas generation source 21 generates hydrocarbon gas such as acetylene. On the other hand, the tip of the source gas supply pipe 9 is disposed inside the container so as to be detachable from the mouth of the plastic container 7, and is provided with a blowout port 9a. The source gas generated by the source gas generation source 16 can be blown into the plastic container 7 through the source gas supply pipe 9.

The gas barrier film in the present invention refers to a thin film that suppresses oxygen permeability, such as a DLC (diamond-like carbon) film, a Si-containing DLC film, a SiO _x film, an alumina film, or an AlN film. As the source gas generated from the source gas generating source 16, a volatile gas containing the constituent elements of the thin film is selected. As the raw material gas for forming the gas barrier thin film, a publicly known volatile raw material gas can be used.

  As the source gas, for example, when a DLC film is formed, aliphatic hydrocarbons, aromatic hydrocarbons, oxygen-containing hydrocarbons, nitrogen-containing hydrocarbons, etc. that are gaseous or liquid at room temperature are used. In particular, benzene, toluene, o-xylene, m-xylene, p-xylene, cyclohexane and the like having 6 or more carbon atoms are desirable. When used for food containers, aliphatic hydrocarbons from the viewpoint of hygiene, especially ethylene hydrocarbons such as ethylene, propylene or butylene, or acetylene hydrocarbons such as acetylene, arylene or 1-butyne Is preferred. These raw materials may be used alone, or may be used as a mixed gas of two or more. Further, these gases may be diluted with a rare gas such as argon or helium. In addition, when a silicon-containing DLC film is formed, a Si-containing hydrocarbon gas is used.

The DLC film referred to in the present invention is a film called i-carbon film or hydrogenated amorphous carbon film (aC: H), and includes a hard carbon film. The DLC film is an amorphous carbon film and also has SP ³ bonds. A hydrocarbon gas such as acetylene gas is used as a source gas for forming the DLC film, and a Si-containing hydrocarbon gas is used as a source gas for forming the Si-containing DLC film. By forming such a DLC film on the inner wall surface of a plastic container, a container that can be used one-way and returnably as a container for carbonated beverages, sparkling beverages, and the like is obtained.

In addition, when a silicon-containing DLC film is formed, a Si-containing hydrocarbon gas is used. Examples of silicified hydrocarbon gas or silicic acid gas include silicon tetrachloride, silane (SiH ₄ ), hexamethyldisilane, vinyltrimethylsilane, methylsilane, dimethylsilane, trimethylsilane, diethylsilane, propylsilane, phenylsilane, and methyltriethoxysilane. , Vinyltriethoxysilane, vinyltrimethoxysilane, tetramethoxysilane, tetraethoxysilane, phenyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane and other organic silane compounds, octamethylcyclotetrasiloxane, 1,1,3 , 3-tetramethyldisiloxane, organic siloxane compounds such as hexamethyldisiloxane (HMDSO) are used. In addition to these materials, aminosilane, silazane and the like are also used.

In the case of forming a SiO _x film (silicon oxide film), for example, a mixed gas of silane and oxygen or a mixed gas of HMDSO and oxygen is used as a source gas.

  The exhaust means 19 includes a vacuum pump 18, a vacuum valve 17, and an exhaust duct (not shown), and exhausts the gas released from the mouth of the plastic container 7 from the vacuum chamber 5 through the through hole 26 and the exhaust passage 31. Is. The other end of the pipe connected to one end of the exhaust passage 31 is connected to the vacuum pump 18 via the vacuum valve 17. The vacuum pump 18 is further connected to an exhaust duct (not shown).

  The high frequency power supply 13 is connected to one end side of the conductor 21 via the matching box 12 and supplies a high frequency to the conductor 21. A matching box 12 is connected to the output side of the high frequency power supply 13, and the high frequency power supply 13 and the matching box 12 constitute a high frequency supply means 11. The high frequency power supply 13 is grounded. The high-frequency power source 13 supplies high-frequency power to the conductor 21 wound along the side wall of the container housing portion 1, whereby inductively coupled plasma (high-frequency) is generated in the spiral enclosed space of the conductor 21. ICP) occurs. In the space occupied by the spacer 20, plasma generation is suppressed, and source gas plasma is generated only in the internal space of the plastic container 7. At this time, plasma having a density one digit higher than that of capacitively coupled plasma is generated. The plasma source gas forms a CVD thin film on the inner wall surface of the container. The frequency of the high-frequency power source is 100 kHz to 100 MHz, and for example, an industrial frequency of 13.56 MHz is used.

  The container according to the present invention includes a container that is used with a lid, a stopper, or a seal, or a container that is used without being used. The size of the opening is determined according to the contents. The plastic container includes a plastic container having a predetermined thickness having moderate rigidity and a plastic container formed by a sheet material having no rigidity. The shape of the cross section with respect to the axis of the container may be round or square. Further, the waist may have a constriction, and the container may have a handle. Examples of the filling material of the plastic container according to the present invention include carbonated beverages, fruit juice beverages, and soft drinks. Moreover, either a returnable container or a one-way container may be used.

  Resin used when molding the plastic container 7 of the present invention is polyethylene terephthalate resin (PET), polybutylene terephthalate resin, polyethylene naphthalate resin, polyethylene resin, polypropylene resin (PP), cycloolefin copolymer resin (COC, cyclic) Olefin copolymer), ionomer resin, poly-4-methylpentene-1 resin, polymethyl methacrylate resin, polystyrene resin, ethylene-vinyl alcohol copolymer resin, acrylonitrile resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyamide resin , Polyamideimide resin, polyacetal resin, polycarbonate resin, polysulfone resin, or tetrafluoroethylene resin, acrylonitrile-styrene resin, acrylonitrile-butadiene-styrene resin It can be exemplified. Among these, PET is particularly preferable.

  In the CVD film forming apparatus 100, the case where the conductor as a coil is one continuous body has been shown, but this is divided into a state in which a plurality of conductors are wound in a tandem relationship. It is good also as supplying high frequency electric power to.

(Second embodiment: CVD film forming apparatus using microwave plasma)
FIG. 4 is a schematic configuration diagram showing a second embodiment of the plasma CVD film forming apparatus according to the present embodiment. Also in FIG. 4, the vacuum chamber 5 is a schematic sectional view in the vertical direction of the container. The plasma CVD film forming apparatus 200 shown in FIG. 4 is a CVD film forming apparatus that converts the source gas in the plastic container 7 into plasma by supplying microwaves. Only differences from the plasma CVD film forming apparatus 100 shown in FIG. 1 will be described.

  In the plasma CVD film forming apparatus 200, the conductor 21 and the high-frequency supply means 11 in FIG. 1 are not provided, but a metal cover 36 that covers the container housing portion 1 and confines microwaves is provided, and an opening provided in the cover 36 is provided. The tuner 33 is connected, and the microwave generator 34 is connected to the tuner 33. A power source (not shown) is connected to the microwave generator 34. The tuner 33 is adjusted so that the source gas is turned into plasma without reflection of microwaves. The frequency of the microwave is, for example, 1 to 30 GHz, and an industrial frequency of 2.45 GHz is used.

  When the microwave is supplied from the microwave generator 34, the microwave propagates in the space 35, the microwave is supplied from the lower part of the container housing portion 1 into the plastic container 7, and the microwave plasma is generated inside the plastic container 7. Will occur. At this time, since the spacer 20 is not disposed between the bottom of the plastic container 7 and the bottom of the internal space 22 of the vacuum chamber, the microwave can enter the container without being affected by the spacer 20. Since the gap space 10 is occupied by the spacer 20, the generation of plasma is suppressed, and the source gas-based plasma is generated only in the internal space of the plastic container 7. The plasma source gas forms a CVD thin film on the inner wall surface of the container.

(Film Forming Method in Apparatus of First Embodiment)
Next, a procedure for forming a DLC film on the inner wall surface of the plastic container 7 using the plasma CVD film forming apparatus (first embodiment) using inductively coupled plasma according to the present embodiment will be described with reference to FIG. To do. The plastic container 7 is a round 500 ml PET bottle. The wall thickness of the container wall is about 0.3 mm.

(Attaching the container to the plasma CVD deposition system)
First, a vent (not shown) is opened to open the vacuum chamber 5 to the atmosphere. After separating the lower fixing portion 2a from the upper fixing portion 2b, the plastic container 7 and the spacer 20 are accommodated in the container accommodating portion 1, and the lower fixing portion 2a is brought into close contact with the upper fixing portion 2b again. Thereby, the plastic container 7 is accommodated in the vacuum chamber 5, and the gap space 10 sandwiched between the inner wall surface of the vacuum chamber 5 and the outer wall surface of the plastic container 7 is occupied by the spacer 20. At this time, the raw material gas supply pipe 9 is inserted from the opening of the plastic container 7.

(Decompression operation)
Next, after closing the vent, the vacuum pump 18 is operated and the vacuum valve 17 is opened, whereby the air in the vacuum chamber 5 is exhausted through the exhaust passage 31. Then, the pressure in the vacuum chamber 5 is reduced until a necessary pressure, for example, 4 Pa is reached. This is because if the degree of vacuum exceeding 4 Pa is sufficient, the container has too many impurities.

(Introduction of raw material gas)
Thereafter, the raw material gas (for example, acetylene gas) sent from the raw material gas generation source 16 with the flow rate controlled by the mass flow controller 15 is introduced into the plastic container 7 from the outlet 9 a at the tip of the raw material gas supply pipe 9. . The supply amount of the source gas is preferably 20 to 200 sccm. The concentration of the source gas becomes constant, and is stabilized at a predetermined film formation pressure, for example, 7 to 27 Pa, by controlling the balance between the gas flow rate and the exhaust capacity.

(Plasma CVD film formation)
By operating the high-frequency power source 13, high-frequency power is applied to the conductor 21 spirally wound along the side wall of the container housing portion 1 through the matching box 12, and the source gas plasma is induced in the plastic container 7. Generate in a combined manner. At this time, matching is performed by the matching box 12 so that the maximum power is supplied to the plasma. As a result, a DLC film is formed on the inner wall surface of the plastic container 7. In addition, the output (for example, 13.56 MHz) of the high frequency power supply 13 is approximately 200 to 3000 W.

  That is, the DLC film is formed on the inner wall surface of the plastic container 7 by a plasma CVD method. Since inductively coupled plasma can generate a plasma density that is one digit higher than that of capacitively coupled plasma, the deposition rate is increased and the deposition time is as short as a few seconds. Here, since the gap space 10 sandwiched between the inner wall surface of the vacuum chamber 5 and the outer wall surface of the plastic container 7 is occupied by the spacer 20, the generation of plasma in the gap space 10 is suppressed.

(Finish film formation)
The high frequency output from the high frequency power supply 13 is stopped, and the supply of the raw material gas is stopped. Thereafter, the acetylene gas in the vacuum chamber 5 is exhausted by the vacuum pump 18. Thereafter, the vacuum valve 17 is closed and the vacuum pump 18 is stopped. Thereafter, the DLC film is formed in the next plastic container by opening the vent (not shown), opening the vacuum chamber 5 to the atmosphere, and repeating the film forming method described above. The film thickness of the DLC film is formed so as to be 10 to 80 nm in the body portion.

(Film Forming Method in Apparatus of Second Embodiment)
In the case of using the film forming apparatus of the first embodiment as to the film forming procedure when the CVD film forming apparatus using the microwave plasma according to the present embodiment shown in FIG. 4 (film forming apparatus of the second embodiment) is used. The same procedure as the film forming procedure is taken. That is, the process of attaching the container to the plasma CVD film forming apparatus, the pressure reducing operation process, the source gas introducing process, the plasma CVD film forming process, and the film forming end process are sequentially performed. Here, the pressure required in the vacuum chamber 5 in the decompression operation step is, for example, reached to 4 Pa. The predetermined film formation pressure in the source gas introduction step is stabilized at 7 to 27 Pa, for example. The microwave output in the plasma film forming process is approximately 200 to 1000 W, the frequency is 2.45 GHz, and the tuner 33 is adjusted so that the source gas is turned into plasma without reflection of the microwave. In the plasma film forming step, the source gas is turned into plasma by microwaves, and a DLC film is formed. Here, since the gap space 10 sandwiched between the inner wall surface of the vacuum chamber 5 and the outer wall surface of the plastic container 7 is occupied by the spacer 20, the generation of plasma in the gap space 10 is suppressed. In the film forming end step, as in the case of the CVD film forming apparatus of the first embodiment, after the vacuum chamber is opened to the atmosphere, the plastic container 7 is taken out. The DLC film is formed to have a thickness of 10 to 80 nm.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail, showing an Example, this invention is limited to description of an Example and is not interpreted.

Example 1
A DLC thin film was formed on the inner wall surface of a square 500 ml PET container using the CVD film forming apparatus according to the first embodiment shown in FIG. Table 1 shows the dimensions of various containers having a capacity of 280 to 15000 ml. In the example, the inner diameter of the inner space of the container housing portion was 110 mm and the height was 400 mm so that all the containers shown in Table 1 could be housed in the same container housing portion 1. The type of "Heat-resistant" is a heat-resistant bottle that can be hot-filled, "Pressure-resistant" is a pressure-resistant bottle that can be filled with carbonated beverages, and "Aseptic" can be aseptically filled Aseptic filling bottle. As shown in FIG. 1, the spacer 20 has an upper spacer 20a disposed on the shoulder of the container and a lower spacer 20b disposed on the trunk. At this time, the maximum gap that could not be occupied by the spacer in the gap space was 5 mm. Film formation was performed with the pressure inside the container being 6.7 Pa and the pressure inside the vacuum chamber and outside the container being 6.7 Pa. Evaluation was performed as follows. First, a black PET bottle was prepared. The outer surface of the PET bottle was painted with a black oil marker. Using the black bottle, the state of discharge inside and outside the bottle was observed with the naked eye. The spacer 20 was made of transparent polymethylpentene. When only the inside of the bottle was discharged, the leakage of light to the outside was partially blocked by the black bottle, so that the outline of the bottle could be clearly identified. When the inside and outside of the bottle were discharged, the outline of the bottle was blurred and blurred. With this method, the presence or absence of discharge in the space on the outer surface of the container in the vacuum chamber, that is, the remaining gap space that could not be occupied by the spacer 20 was evaluated. The case where there was a discharge was evaluated as x, and the case where there was no discharge was evaluated as ◯. The conditions and evaluation results are summarized in Table 2. In Example 1, no discharge occurred in the gap space. Note that the amount of high-frequency power supplied was adjusted so that the film thickness of the DLC film was 30 nm when the film formation time was 1 second. The plastic container thus manufactured had an oxygen permeability equivalent to that of the carbon film coated plastic container described in JP-A-8-53117.

(Example 2 to Example 9)
Using the CVD film forming apparatus according to the first embodiment shown in FIG. 1, a DLC film was formed according to the conditions shown in Table 2 as in Example 1. Spacers were prepared according to the shape and capacity of the container. The supply amount of the high frequency power was adjusted so that the film thickness of the DLC film was 30 nm when the film formation time was 1 second. In all of Examples 2 to 9, no discharge occurred in the gap space.

(Comparative Examples 1 to 3)
Using the CVD film forming apparatus according to the first embodiment shown in FIG. 1, a DLC film was formed according to the conditions shown in Table 2 without arranging spacers. The supply amount of the high frequency power was adjusted so that the film thickness of the DLC film was 30 nm when the film formation time was 1 second. In Comparative Examples 1 to 3, the pressure was changed, but in all cases, discharge occurred in the gap space. Therefore, it was found that a spacer was necessary.

(Example 10, Example 11)
A DLC film was formed according to the conditions shown in Table 2 using the CVD film forming apparatus according to the second embodiment shown in FIG. Note that the supply amount of the microwave was adjusted so that the film thickness of the DLC film was 30 nm when the film formation time was 1 second. In both Example 10 and Example 11, no discharge occurred in the gap space. The plastic container thus manufactured had an oxygen permeability equivalent to that of the carbon film coated plastic container described in JP-A-8-53117.

(Comparative Example 4 and Comparative Example 5)
Using the CVD film forming apparatus according to the second embodiment shown in FIG. 4, a DLC film was formed according to the conditions shown in Table 2 without arranging spacers. The supply amount of the microwave was adjusted so that the film thickness of the DLC film was 30 nm when the film formation time was 1 second. In Comparative Example 4 and Comparative Example 5, the pressure was changed, but in both cases, discharge occurred in the gap space. Therefore, it was found that a spacer was necessary.

(Reference Example 1)
A DLC film was formed in the same manner as in Example 5 except that the pressure was changed to 26.6 Pa using the CVD film forming apparatus according to the first embodiment shown in FIG. The condition that the maximum space of the gap space is 10 mm is the same as that in Example 5, but discharge was generated in the gap space because the pressure was high. Therefore, it was suggested that the maximum interval should be reduced when forming a film with the pressure increased.

(Reference Example 2)
A DLC film was formed in the same manner as in Example 6 except that the pressure was set to 13.3 Pa using the CVD film forming apparatus according to the first embodiment shown in FIG. The condition that the maximum gap space is 20 mm is the same as in Example 6, but discharge was generated in the gap space because the pressure was high. Therefore, it was suggested that the maximum interval should be reduced when forming a film with the pressure increased.

(Reference Example 3)
A DLC film was formed in the same manner as in Example 6 except that the pressure was set to 26.6 Pa using the CVD film forming apparatus according to the first embodiment shown in FIG. The condition that the maximum gap space is 20 mm is the same as in Example 6, but discharge was generated in the gap space because the pressure was high. Therefore, it was suggested that the maximum interval should be reduced when forming a film with the pressure increased.

  From Reference Examples 1 to 3 and Examples 5 and 6, the following can be understood. Under the condition where the pressure in the vacuum chamber 5 is 6.7 Pa or more, plasma generation can be suppressed by setting at least the maximum interval to 20 mm. Furthermore, plasma generation can be suppressed by setting the maximum interval to 10 mm or less under the condition where the pressure in the vacuum chamber 5 is 13.3 Pa or more. When the pressure in the vacuum chamber 5 is 26.6 Pa or more, the generation of plasma can be suppressed by setting the maximum interval to 5 mm or less. The results are summarized in FIG.

  Referring to Examples 1 to 11, when a film is formed on the inner wall surface of a plastic container, the same CVD film forming apparatus can be used for each container having a different shape except for a spacer. It can be seen that any method of wave plasma can suppress the generation of plasma in the gap space without providing a pressure difference control mechanism between the internal space and the external space of the container.

It is a schematic block diagram which shows one form of the inductively coupled plasma type CVD film-forming apparatus which concerns on this embodiment. It is an example of the shape of a spacer for a square plastic container, (a) is a longitudinal sectional view of the upper spacer, (b) is a view of the upper spacer as viewed from the A direction, (c) is a longitudinal sectional view of the lower spacer, (d ) Shows a view of the lower spacer as seen from the B direction. It is a shape example of a spacer for a round plastic container, (a) is a longitudinal sectional view of the upper spacer, (b) is a view of the upper spacer viewed from the C direction, (c) is a longitudinal sectional view of the lower spacer, (d ) Shows a view of the lower spacer as viewed from the D direction. It is a schematic block diagram which shows one form of the CVD film-forming apparatus of the microwave plasma system which concerns on this embodiment. It is a graph which shows the relationship between the largest clearance gap and the upper limit pressure of the vacuum chamber which does not discharge in clearance gap space.

Explanation of symbols

1, container housing part 2, fixing part 2a, lower fixing part 2b, upper fixing part 3, lid 4, recess 5, vacuum chamber 6, opening 7 of container housing part, plastic container 8, resin sealing member 9, raw material Gas supply pipe 9a, outlet 10, gap space 11, high frequency supply means 12, matching box 13, high frequency power supply 14, raw material gas supply means 15, mass flow controller 16, raw material gas generation sources 17 and 30, vacuum valve 18, vacuum pump 19, exhaust means 20, spacer 20a, upper spacer 20b, lower spacer 21, conductor 22, vacuum chamber internal space 23, first circular recess 24, second circular recess 26, through hole 28, opening 29, piping 31, Exhaust passage 32, gas flow path 33, tuner 34, microwave generator 35, space 36, cover 100, 200, plasma CVD process Equipment

Claims (12)

A vacuum chamber containing a plastic container;
A spacer made of an insulator disposed in a gap space sandwiched between an inner wall surface of the vacuum chamber and an outer wall surface of the plastic container;
A source gas supply pipe that is detachably disposed in the plastic container and supplies a source gas to the plastic container;
Exhaust means for exhausting the internal gas of the vacuum chamber;
Plasma generating means for converting the source gas supplied into the plastic container into plasma;
A plasma CVD film forming apparatus comprising:   The plasma CVD film forming apparatus according to claim 1, wherein the plastic container is disposed so that a bottom of the plastic container and an inner bottom of the vacuum chamber are in contact with each other. The plasma generating means includes a conductor spirally wound along a side wall of the vacuum chamber, and a high frequency power source for applying high frequency power to the conductor,
3. The plasma CVD film forming apparatus according to claim 1, wherein the source gas is turned into plasma by an inductive coupling method.   3. The plasma CVD film forming apparatus according to claim 1, wherein the plasma generation unit converts the source gas into plasma by supplying a microwave to the source gas. 4.   5. The plasma CVD film forming apparatus according to claim 1, wherein the spacer is formed so as to be dividable along a vertically divided surface of the plastic container.   6. The spacer according to claim 1, 2, 3, 4 or 5, wherein the spacer has a heat resistance with a continuous use temperature of 100 ° C or higher and a water absorption rate of 0.30% or less. Plasma CVD film forming equipment.   The spacer is formed of at least one of fluororesin, silicon resin, polyimide, polyamideimide, polyphenylene sulfide, polymethylpentene, cyclic olefin copolymer, or polyetheretherketone. The plasma CVD film-forming apparatus of description.   The spacer has a shape in which a maximum gap between the wall surface of the spacer and the inner wall surface of the vacuum chamber or a maximum gap between the wall surface of the spacer and the outer wall surface of the plastic container is 20 mm or less. The plasma CVD film forming apparatus according to 1, 2, 3, 4, 5, 6 or 7. Storing a plastic container and a spacer made of an insulator for occupying a gap space sandwiched between an inner wall surface of the vacuum chamber and an outer wall surface of the plastic container in a vacuum chamber;
Exhausting the internal gas of the vacuum chamber;
Supplying a raw material gas into the plastic container;
Generating a source gas-based plasma only in the internal space of the plastic container, and forming a gas barrier thin film on the inner wall surface of the plastic container;
A method for producing a barrier plastic container, comprising:   The method for producing a barrier plastic container according to claim 9, wherein the plastic container is arranged in the vacuum chamber so that a bottom of the plastic container and an inner bottom of the vacuum chamber are in contact with each other.   The method for producing a barrier plastic container according to claim 9 or 10, wherein the source gas is plasmatized by an inductive coupling method or plasmatized by a microwave. The method for producing a barrier plastic container according to claim 9, 10 or 11, wherein a carbon film, a silicon-containing carbon film or a SiO _x film is formed as the gas barrier thin film.

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