JP4854983B2 - Plasma CVD film forming apparatus and method for manufacturing plastic container having gas barrier property - Google Patents

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 plastic container having gas barrier properties.

  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.

  Further, in a plasma CVD film forming apparatus using inductively coupled plasma, there is a technique for uniformly forming a film on the inner surface of a structure (see, for example, Patent Document 4).

Japanese Patent No. 2788412 Japanese Patent No. 3072269 WO 03 / 016149A1 Japanese Patent Laid-Open No. 2004-127739

  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 techniques described in Patent Document 3 and Patent Document 4, it is not necessary to form an external electrode having an internal space substantially similar to the outer shape of the target container. That is, a large chamber may be used so that the largest container among the desired containers can be accommodated. However, the container often has a vertically long shape, and it is not easy to generate plasma uniformly in the vertically long shape. Therefore, the technique described in Patent Document 4 is an apparatus that can make the electron density uniform in the longitudinal direction of the container by supplying high-frequency waves to two circular coils arranged in a column in parallel connection.

  However, since containers differ not only in height but also in diameter when the capacity is different, the positional relationship between the coil and the wall surface of the container varies depending on the capacity. In the case of inductively coupled plasma, the electric field generated by the coil includes not only the electric field induced by Faraday's law of electromagnetic induction, but also the quasi-electrostatic field (electric field according to the electrostatic field) created by the charge on the coil surface. This electric field includes electric field lines of a quasi-electrostatic field perpendicular to the wall surface of the plastic container. Conventional apparatuses using inductively coupled plasma including the apparatus of Patent Document 4 use a round coil. When a round coil is used, the electric field lines of the quasi-electrostatic field are concentrated toward the central axis of the round coil and are formed so as to surround the central axis of the round coil. Accordingly, when viewed in the container height direction, the parallel lines of electric field lines of the quasi-electrostatic field are poor, and it is difficult to form a uniform film quality in the container height direction.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a plasma CVD film forming apparatus capable of forming a film having a uniform film quality in a container height direction with respect to containers having different capacities without exchanging chambers. . Another object of the present invention is to provide a method for producing a plastic container having gas barrier properties in which uniform film quality is formed in the container height direction for containers of different capacities.

The inventors of the present invention have made a ribbon-shaped coil having a rectangular cross section instead of a round coil along the wall surface of the vacuum chamber , with the ribbon-shaped coil in the width direction surface facing the side wall surface of the vacuum chamber. By wrapping in a spiral shape, the electric field lines of the quasi-electrostatic field generated when high frequency power is supplied to the ribbon coil are formed close to the normal direction with respect to the surface in the width direction of the ribbon coil. The headline and the present invention were completed. That is, a plasma CVD film forming apparatus according to the present invention includes a vacuum chamber that accommodates a plastic container, a ribbon-shaped coil having a rectangular cross section wound spirally along the side wall of the vacuum chamber, and the plastic A raw material gas supply pipe that is detachably disposed inside the container and supplies a raw material gas to the plastic container, an exhaust means for exhausting the internal gas of the vacuum chamber, and a high frequency that applies high frequency power to the ribbon coil and supplying means, possess, and wherein the width direction of the surface of the ribbon-like coil and the side wall surface of the vacuum chamber is facing.

  In the plasma CVD film forming apparatus according to the present invention, the ribbon-shaped coil preferably has a length that is at least three times as wide as the thickness. The concentration of the electric field lines of the quasi-electrostatic field can be prevented, and the electric field lines of the quasi-electrostatic field can be formed closer to the normal direction with respect to the surface of the ribbon coil.

In the plasma CVD film forming apparatus according to the present invention, when the width of the ribbon-shaped coil is W, the number of turns is N, and the height of the internal space of the vacuum chamber is H, the coating represented by Formula 1 The rate C is preferably 10 to 30%.
(Formula 1) C (%) = W × N / H × 100
The concentration of the electric field lines of the quasi-electrostatic field can be prevented, and the electric field lines of the quasi-electrostatic field can be formed closer to the normal direction with respect to the surface of the ribbon coil.

  In the plasma CVD film-forming apparatus according to the present invention, the number of turns of the ribbon-like coil is preferably 4 or more and 8 or less. If the number of turns is large, the impedance applied to the ribbon-shaped coil increases and the voltage increases, so that abnormal discharge is likely to occur or no discharge occurs.

  In the plasma CVD film forming apparatus according to the present invention, a plurality of the vacuum chambers in which the ribbon-like coils are spirally wound are arranged, and each ribbon-like coil is connected in parallel to the high-frequency supply means Is included. A plurality of chambers can be used to form a film in a plurality of containers at the same time.

According to the method of manufacturing a plastic container having gas barrier properties according to the present invention, a ribbon-shaped coil having a rectangular cross-section is formed along a side wall of the vacuum chamber and a side surface of the vacuum chamber along the side wall of the vacuum chamber. The plastic container is housed in the vacuum chamber so that the plastic container is substantially parallel to the winding axis of the ribbon-like coil , and the ribbon container is substantially parallel to the winding axis of the ribbon-like coil. Evacuating the internal gas of the vacuum chamber, supplying a raw material gas into the plastic container, supplying high-frequency power to the ribbon-like coil to plasma the raw material gas, Forming a gas barrier thin film on the inner wall surface of the container.

In the method for manufacturing a plastic container having gas barrier properties according to the present invention, when high-frequency power is supplied to the ribbon-shaped coil, the electric field lines of the quasi-electrostatic field are parallel to the transverse cross-sectional direction of the axis of the plastic container. Preferably it is generated.

In the method for producing a plastic container having gas barrier properties 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.

  The plasma CVD film forming apparatus according to the present invention can form a film having a uniform film quality in the container height direction for containers of different capacities without exchanging the chamber. The method for producing a plastic container having gas barrier properties according to the present invention can produce a container in which a film having a uniform film quality is formed in the container height direction for containers of different capacities.

  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.

  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 the present embodiment includes a vacuum chamber 5 that houses a plastic container 7, and a ribbon-shaped coil 21 that is spirally wound along the side wall of the vacuum chamber 5. The raw material gas supply pipe 9 for supplying the raw material gas to the plastic container 7, the exhaust means 19 for exhausting the internal gas of the vacuum chamber 5, and the ribbon coil 21 are provided with high frequency power. And a high-frequency supply means 11 for applying. That is, the plasma CVD film forming apparatus 100 is a plasma CVD film forming apparatus that converts a source gas into plasma by a high frequency ICP 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 ribbon-shaped coil 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 ribbon-shaped coil 21 may be wound spirally along the side wall of the container housing portion 1, and may be wound on the outer wall side of the container housing portion 1 or disposed on the inner wall side. Or you may arrange | position inside the container accommodating part 1. FIG. Here, it is preferable that the main surface of the ribbon-shaped coil 21 and the outer wall surface of the container housing portion 1 are wound so as to face each other. A high frequency power supply 13 is connected to one end of the ribbon coil 21 via a matching box 12. The other end of the ribbon coil 21 is grounded. The ribbon-like coil 21 is preferably made of a highly conductive metal such as copper or an alloy, and the cross-sectional shape of the ribbon-like coil 21 is rectangular as shown in FIG. The ribbon-shaped coil 21 may be hollow as a cylinder. When the ribbon-like coil 21 has a circular cross-sectional shape, that is, when the ribbon-like coil 21 is replaced with a normal round coil, the electric field lines of the quasi-electrostatic field concentrate on the central axis of the round coil, and the quasi-electrostatic field lines are quasi The uniformity of the electrostatic field is lost. Therefore, the ribbon-shaped coil 21 has a length that is at least three times as wide as the thickness so that electric field lines of a quasi-electrostatic field are formed in the normal direction of the surface of the ribbon-shaped coil 21. It is preferable. When the length is less than 3 times, the electric field lines of the quasi-electrostatic field tend to concentrate toward the central axis like a normal round coil. Further, the number of turns of the ribbon-shaped coil 21 is appropriately determined depending on the height of the container housing portion 1 and the inner diameter thereof, but the number of turns of the ribbon-shaped coil 21 is preferably 4 or more and 8 or less. If it is less than 4 turns, it is difficult to ensure the uniformity of the film quality. If it exceeds 8 turns, the impedance applied to the ribbon-like coil 21 rises and the voltage rises, so that abnormal discharge is likely to occur or no discharge occurs. Furthermore, when the width of the ribbon-shaped coil 21 is W, the number of turns is N, and the height of the internal space 22 of the vacuum chamber 5 is H, the coverage C represented by Equation 1 is 10 to 30%. Preferably there is. If the coverage C is less than 10%, it is difficult to ensure the uniformity of the film quality. If the coverage C is more than 30%, the gap between the ribbon coils becomes narrow, and abnormal discharge tends to occur between the gaps between the ribbon coils. is there.
(Formula 1) C (%) = W × N / H × 100

  Note that an insulating spacer (not shown) made of a heat-resistant resin such as a fluororesin may be disposed so as to occupy the gap space on the outer surface side of the plastic container 7 in the internal space 22 of the vacuum chamber 5. Generation of discharge in the gap space can be suppressed.

  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 16 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. Silicified hydrocarbon gas or silicic acid gas includes silicon tetrachloride, silane (SiH ₄ ), hexamethyldisilane, vinyltrimethylsilane, methylsilane, dimethylsilane, trimethylsilane, diethylsilane, propylsilane, phenylsilane, 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). The exhaust means 19 exhausts the gas discharged from the mouth of the plastic container 7 from the vacuum chamber 5 through the exhaust passage 31. . 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 ribbon coil 21 via the matching box 12 and supplies high frequency to the ribbon coil 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 a ribbon-shaped coil 21 spirally wound along the side wall of the container housing portion 1, and thereby, in a space surrounded by a spiral formed by the ribbon-shaped coil 21. Inductively coupled plasma (high frequency ICP) is generated. 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 according to the present embodiment, the case where the ribbon-shaped coil is one continuous body is shown, but a state in which a plurality of ribbon-shaped coils are spirally wound in a tandem relationship. The high frequency power may be supplied to each ribbon coil.

  The CVD film forming apparatus according to this embodiment may be a plurality of simultaneous film forming apparatuses as shown in FIG. FIG. 2 is a schematic diagram showing an embodiment of a CVD film forming apparatus capable of simultaneously forming a plurality of films according to this embodiment. FIG. 2 is a diagram in which some members are omitted. The CVD film forming apparatus 200 includes a plurality of vacuum chambers 5b, 5c, 5d equivalent to the vacuum chamber 5a in which the ribbon-like coil 21a is spirally wound, and one end of each ribbon-like coil 21a, 21b, 21c, 21d. Are connected in parallel to the high-frequency supply means 11. The other end of each ribbon coil 21a, 21b, 21c, 21d is grounded via each variable capacitor 28a, 28b, 28c, 28d. Each variable capacitor 28a, 28b, 28c, 28d adjusts the distribution of high-frequency power in order to generate uniform source gas plasma in each vacuum chamber 5a, 5b, 5c, 5d. In the CVD film forming apparatus 200, a gas barrier thin film can be formed on the inner wall surfaces of the plastic containers 7a, 7b, 7c, 7d simultaneously in the vacuum chambers 5a, 5b, 5c, 5d.

  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 according to the present embodiment will be described with reference to FIG. 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 part 2a from the upper fixing part 2b, the plastic container 7 is accommodated in the container accommodating part 1, and the lower fixing part 2a is brought into close contact with the upper fixing part 2b again. Thereby, the plastic container 7 is accommodated in the vacuum chamber 5 so that the axis of the plastic container 7 is substantially parallel to the winding axis of the ribbon-like coil 21 wound spirally along the side wall of the vacuum chamber 5. Is done. 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 ribbon coil 21 spirally wound along the side wall of the container housing portion 1 through the matching box 12, and the source gas plasma is generated in the plastic container 7. generate. 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 2 seconds or less. Further, a quasi-static electric field (quasi-electrostatic field) is generated between the plasma and the coil due to the charge on the coil surface. By supplying the high frequency power to the ribbon coil 21 instead of the round coil, the electric field lines 33 of the quasi-electrostatic field are kept parallel over the height direction of the plastic container wall as shown in FIG. However, it is realized to generate. FIG. 3 is a conceptual diagram showing the electric field lines of the quasi-electrostatic field and the state of the quasi-electrostatic field when high-frequency power is supplied. When (a) is a ribbon coil, (b) is a round coil. When used. Reference numeral 35 represents the generated plasma. FIG. 3 is a diagram in which some members are omitted. In the CVD film forming apparatus shown in FIG. 3A, when the electric force lines 33 of the quasi-electrostatic field are generated while maintaining parallelism with respect to the horizontal direction, the direction normal to the surface of the ribbon coil 21. The quasi-electrostatic field 34 caused by the charge on the surface of the ribbon coil 21 can be made uniform in the container height direction. Therefore, a DLC film having a uniform film quality can be formed on the inner wall surface of the plastic container 7. On the other hand, in the conventional film forming apparatus using a round coil shown in FIG. 3B, the electric field lines 33 of the quasi-electrostatic field are formed toward the central axis of the round coil 32. Cannot be generated parallel to And the quasi-electrostatic field 34 resulting from the electric charge of the surface of the round coil 32 will become non-uniform | heterogenous with respect to the container height direction. Therefore, a DLC film having a sufficiently uniform film quality cannot be formed on the inner wall surface of the plastic container 7.

(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.

  The CVD film forming apparatus 200 can also form a uniform DLC film on the inner wall surface of the plastic container 7 through the same process.

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

The apparatus used in the examples was the CVD film forming apparatus 100 shown in FIG. 1 or the CVD film forming apparatus 200 shown in FIG. Table 1 shows the dimensions of various containers having a capacity of 280 to 1500 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. In Table 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 a carbonated beverage, and “sterile” is aseptically filled. Aseptic filling bottle capable.

In the following examples, acetylene gas was used as a source gas, and a DLC thin film was formed on the inner wall surface of a PET container. The pressure in the vacuum chamber during film formation was 13.3 Pa.

Example 1
A CVD film forming apparatus 100 was used. The PET container used was a round shape of 280 ml. The ribbon coil was made of copper, the number of turns was 4, the width was 10 mm, and the thickness was 1 mm. At this time, the coverage C obtained by Equation 1 was 10%. A high frequency of 13.56 MHz was supplied to the ribbon coil at 600 W. The film formation time was 1 second. At this time, the thickness of the DLC thin film was 60 nm. The results are shown in Table 2.

Evaluation was performed as follows. Table 2 summarizes the evaluation results.
(Oxygen gas permeability)
The measurement was performed under the conditions of 22 ° C. and 60% RH using an Oxtran manufactured by Modern Control. After the start of measurement, the value of oxygen gas permeability was read when it became stable after 7 days.
(Film thickness)
It measured with the stylus type level difference meter of tenchol alpha-step500.
(Film quality uniformity)
Evaluation of the uniformity of the film quality was judged by the value of oxygen gas permeability. When the oxygen gas permeability is 0.005 cc / day / container or less, the film quality uniformity is excellent, and when it exceeds 0.005 cc / day / container and 0.014 cc / day / container or less, the film quality uniformity In the case of slightly inferior, Δ, and in the case of 0.014 cc / day / container over, the uniformity of the film quality was inferior, and was evaluated as x. Here, the film quality homogeneity is not the film thickness uniformity but the film quality uniformity. Film quality depends on composition and density.

(Examples 2 to 11) In Examples 2 to 11, films were formed under the conditions shown in Table 2, respectively. The results are shown in Table 2.

(Example 21, Example 22) In Example 21 and Example 22, films were formed under the conditions shown in Table 2 using the CVD film forming apparatus 200 of FIG. The results are shown in Table 2.

(Example 31, Example 32) For Example 31 and Example 32, the CVD film forming apparatus 200 of FIG. 1 was used, the high frequency frequency was changed to 400 kHz, and the conditions shown in Table 2 were used. Film formation was performed. The results are shown in Table 2.

Comparative Examples 1 to 4 For each PET container having a capacity of 280 ml, 350 ml, 500 ml, and 1000 ml, the oxygen gas permeability was measured as a control without performing film formation. The results are shown in Table 2.

(Comparative Example 5 to Comparative Example 10) In Comparative Examples 5 to 10, films were formed under the conditions shown in Table 2 using the CVD film forming apparatus 300 in FIG. High frequency supply means (not shown) is connected to the round coil 32. The results are shown in Table 2.

According to Examples 1 to 11, a DLC thin film is formed on the inner wall surface of a container having a bottle capacity of 280 ml to 1000 ml without replacing the components of the film forming apparatus for each container type using one kind of vacuum chamber. Can be formed with a thickness of 60 nm. The oxygen gas permeability was 0.002 to 0.004 cc / day / container. Therefore, a DLC thin film having a uniform film quality could be formed on the entire inner wall surface of the container. When compared with the controls of Comparative Examples 1 to 4, it can be seen that the oxygen gas permeability was reduced to about 1/8 to 1/15.

According to Example 21 and Example 22, DLC thin films having substantially the same film thickness could be simultaneously formed on the inner wall surfaces of the four PET containers. The oxygen gas permeability was 0.002 to 0.004 cc / day / container. Therefore, a DLC thin film having a uniform film quality could be formed on the entire inner wall surface in any container. Compared with the control of Comparative Example 3, it can be seen that the oxygen gas permeability was reduced to 1/10.

According to Example 31 and Example 32, the DLC thin film could be similarly formed on the inner wall surface of the container even when the frequency of the high frequency was 400 kHz. When the film formation time was 1.5 seconds, the film thickness was 30 nm, and the film formation rate was small compared to Examples 1 to 11 and Examples 21 and 22. The oxygen gas permeability was 0.004 cc / day / container (Example 31) and 0.003 cc / day / container (Example 32). Therefore, a DLC thin film having a uniform film quality could be formed on the entire inner wall surface of the container. It can be seen that the oxygen gas permeability decreased to 2/10 to 1/10 compared to the control (Comparative Example 3).

  In Comparative Example 5, the oxygen gas permeability was 0.018 cc / day / container. This is probably because the round coil was used, and the coverage was as small as 3.6%, and it was not possible to form a film with a uniform film quality in the container height direction. In Comparative Example 8, Comparative Example 9, and Comparative Example 10, as in Comparative Example 5, the coverages were as small as 8%, 6%, and 6%, respectively, and the oxygen gas permeability was 0.010 cc / day / container, 0 0.008 cc / day / container and 0.014 cc / day / container. It is considered that, as in Comparative Example 5, it was impossible to form a film with a uniform film quality in the container height direction.

  Since Comparative Example 6 did not discharge, a DLC film-coated PET container could not be obtained. Although the covering rate was 10% by setting the number of turns to 10, it is considered that the impedance applied to the round coil increased and no discharge occurred.

  In Comparative Example 7, the coverage was 10% by setting the number of turns to 10 and discharging was performed semi-forcedly with a high frequency power of 1200 W. However, the oxygen gas permeability was 0.009 cc / day / container and a uniform film quality could not be formed. This is probably because abnormal discharge occurred.

It is a schematic block diagram which shows one form of the plasma CVD film-forming apparatus which concerns on this embodiment. It is the schematic which shows one form of the CVD film-forming apparatus which can form into multiple films simultaneously concerning this embodiment. It is the conceptual diagram which showed the mode of the electric force line of the quasi-electrostatic field at the time of high frequency electric power supply, and the state of a quasi-electrostatic field, (a) when a ribbon coil is used, (b) when a round coil is used. Show.

Explanation of symbols

1, container housing part 2, fixing part 2a, lower fixing part 2b, upper fixing part 3, lid 4, recesses 5, 5a, 5b, 5c, 5d, vacuum chamber 6, openings 7, 7a, 7b of container housing part 7c, 7d, plastic container 8, resin sealing member 9, raw material gas supply pipe 9a, outlet 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 Sources 17 and 30, vacuum valve 18, vacuum pump 19, exhaust means 21, 21 a, 21 b, 21 c and 21 d, ribbon-like coil 22, vacuum chamber inner space 23, first circular recess 24, second circular recess 28 a, 28b, 28c, 28d, variable capacitor 29, piping 31, exhaust passage 32, round coil 33, quasi-electrostatic electric field lines 34, quasi-electrostatic field 35, plus 100,200, plasma CVD film-forming apparatus 300, a plasma CVD film forming apparatus (Comparative Example)

Claims (8)

A vacuum chamber containing a plastic container;
A ribbon-shaped coil having a rectangular cross-sectional shape wound spirally along the side wall of the vacuum chamber;
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;
High-frequency supply means for applying high-frequency power to the ribbon-shaped coil;
Have a, and a plasma CVD film forming apparatus, wherein the width direction of the surface of the ribbon-like coil and the side wall surface of the vacuum chamber is facing.   The plasma CVD film forming apparatus according to claim 1, wherein the ribbon-like coil has a length that is at least three times as wide as the thickness. When the width of the ribbon-shaped coil is W, the number of turns is N, and the height of the internal space of the vacuum chamber is H, the coverage C represented by Equation 1 is 10 to 30%. The plasma CVD film-forming apparatus according to claim 1 or 2, characterized in that:
(Formula 1) C (%) = W × N / H × 100   4. The plasma CVD film forming apparatus according to claim 1, wherein the number of windings of the ribbon-shaped coil is 4 or more and 8 or less.   A plurality of the vacuum chambers in which the ribbon-like coils are spirally wound are arranged, and each ribbon-like coil is connected in parallel to the high-frequency supply means. Or the plasma CVD film-forming apparatus of 4. A ribbon-shaped coil having a rectangular cross-sectional shape is spirally wound along the side wall of the vacuum chamber in a state where the surface in the width direction of the ribbon-shaped coil faces the side wall surface of the vacuum chamber , Storing the plastic container in the vacuum chamber such that the axis of the plastic container is substantially parallel to the winding axis of the ribbon-shaped coil;
Exhausting the internal gas of the vacuum chamber;
Supplying a raw material gas into the plastic container;
Supplying high-frequency power to the ribbon-shaped coil, converting the source gas into plasma, and forming a gas barrier thin film on the inner wall surface of the plastic container;
A method for producing a plastic container having gas barrier properties, comprising: The gas barrier property according to claim 6 , wherein when high-frequency power is supplied to the ribbon-like coil, electric lines of force of a quasi-electrostatic field are generated in parallel to the transverse cross-sectional direction of the axis of the plastic container. A method for producing a plastic container. The method for producing a plastic container having gas barrier properties according to claim 6 or 7, 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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