JP6855994B2 - Manufacturing method of film forming equipment, film forming system and plastic container - Google Patents

Description

The present application discloses an apparatus for forming a gas barrier carbon film on the inner surface of a plastic container.

As disclosed in Patent Documents 1 to 3, a technique for forming a gas barrier carbon film on the inner surface of a plastic container is known. Patent Document 1 discloses a technique for forming a gas barrier film on the inner surface of a plastic container using an external electrode having a flat bottom surface with respect to a plastic container having a flat bottom. The bottom is in direct contact with the bottom of the external electrode. Patent Document 2 discloses a technique for forming a gas barrier film on the inner surface of a plastic container having a concave space at the bottom. At the time of film formation, (1) whether a petal-shaped dielectric is brought into close contact with the bottom of the bottle. , (2) Petal-shaped conductors are installed with a gap from the bottom of the bottle. Patent Document 3 discloses a technique for forming a gas barrier film on the inner surface of a plastic container using an external electrode having a flat bottom surface with respect to a plastic container having a flat bottom. A dielectric member having a flat bottom surface is arranged between them, and the bottom portion of the plastic bottle and the bottom surface of the dielectric member are in direct contact with each other at the time of film formation.

Japanese Patent No. 3746725 Japanese Patent No. 4467989 Japanese Patent No. 5897998

According to the techniques disclosed in Patent Documents 1 to 3, a gas barrier carbon film can be uniformly formed on the inner surface of the plastic container to some extent. However, according to the new findings of the present inventors, when a gas barrier carbon film is formed on the inner surface of the plastic container by the technique disclosed in Patent Documents 1 to 3, the film is formed especially on the bottom of the plastic container. There is a problem that unevenness occurs and the color of the bottom is darker than that of the body of the plastic container. Further, in the case of Patent Document 2, it is necessary to produce a petal-shaped member made of a dielectric or a conductor matching the shape of the bottom of the bottle, and preparation and cost for producing the petal-shaped member according to the bottles having different bottom shapes. This required a large load on the commercial production of film-forming bottles.

The present application is an apparatus for forming a carbon film on the inner surface of the plastic container by generating plasma while supplying a raw material gas to the inside of the plastic container as one of means for solving the above-mentioned problems. A bottomed tubular external electrode having a bottom and a bottom, and a bottomed tubular dielectric member installed inside the external electrode and having a side and a bottom, the bottom of the dielectric member. The upper surface of the film discloses a film forming apparatus having a recess substantially in the center thereof.

The "plastic container" means a plastic container having a bottom and a mouth portion whose diameter is smaller than that of the body portion.
The "carbon film" may be any gas barrier film mainly composed of carbon, and may be any of a DLC film (diamond-like carbon film), an amorphous carbon film, and the like.
"The upper surface of the bottom portion of the dielectric member" means the inner surface of the bottom of the dielectric member.
The "recess" means a portion that is recessed downward. That is, the upper surface of the bottom portion of the dielectric member has a central portion recessed downward as compared with other portions.

In the film forming apparatus of the present disclosure, a fixing member made of a dielectric is provided substantially in the center of the upper surface of the bottom portion of the dielectric member, and the upper surface of the fixing member constitutes at least a part of the surface of the recess. It is preferable to have.

In the film forming apparatus of the present disclosure, the fixing member has a head on the dielectric member side and a screw portion on the external electrode side, and the dielectric member and the external electrode are provided via the fixing member. Are preferably fixed to each other.

In the film forming apparatus of the present disclosure, the fixing member is preferably made of a dielectric having a relative permittivity of 1.5 or more and 20 or less.

In the film forming apparatus of the present disclosure, the dielectric member is preferably made of a dielectric having a relative permittivity of 1.5 or more and 20 or less.

In the film forming apparatus of the present disclosure, the ratio of the area of the concave portion to the total area of the upper surface of the bottom portion of the dielectric member ((recessed area / total area) × 100%) is 0.2% in top view. It is preferably 10% or more and 10% or less.

The present application is a system in which a plastic container is installed inside the dielectric member of the film forming apparatus of the present disclosure to form a carbon film on the inner surface of the plastic container as one of means for solving the above problems. The present invention discloses a film forming system in which the distance between the lower surface of the center of the bottom of the plastic container and the surface of the concave portion of the bottom of the dielectric member is 3.0 mm or more and 25 mm or less.

The “surface of the recess” means the substantially horizontal bottom surface when the recess has a substantially horizontal bottom surface. On the other hand, when the recess does not have a substantially horizontal bottom surface and consists only of the side surface (for example, when the recess is not the bottom surface but the bottom point such as an inverted cone), it means the deepest part of the recess.

In the film forming system of the present disclosure, it is preferable that the diameter of the recess is 2% or more and 40% or less of the ground contact diameter of the plastic container in the top view.

In the present application, as one of the means for solving the above problems, a plastic container is installed inside the dielectric member of the film forming apparatus of the present disclosure, and a carbon film is formed on the inner surface of the plastic container to form a plastic. Disclosed is a method for manufacturing a container, wherein the distance between the lower surface of the bottom center of the plastic container and the surface of the concave portion of the bottom of the dielectric member is 3.0 mm or more and 25 mm or less. To do.

In the manufacturing method of the present disclosure, it is preferable that the diameter of the recess is 0.2% or more and 20% or less of the ground contact diameter of the plastic container in the top view.

According to the new findings of the present inventors, when a dielectric member is arranged inside the external electrode and a plastic container is arranged inside the dielectric member to perform plasma film formation of a carbon film, the dielectric material is formed. If the distance between the upper surface of the bottom of the member and the center of the bottom of the plastic container is too close, plasma concentrates in the center of the bottom of the plastic container, and as a result, the color of the carbon film becomes darker at the bottom of the plastic container. In particular, when the dielectric member is fixed to the external electrode using the fixing member, plasma tends to concentrate when the head of the fixing member protrudes from the upper surface of the bottom of the dielectric member. On the other hand, in the film forming apparatus and the like of the present disclosure, a recess is provided in the center of the upper surface of the bottom of the dielectric member, and a space is provided between the upper surface of the bottom of the dielectric member and the center of the bottom of the plastic container. ing. As a result, the concentration of plasma can be suppressed, and uneven film formation and color darkening at the bottom of the plastic container can be suppressed. Furthermore, since a high-quality film-forming bottle can be manufactured without manufacturing a custom-made member for each bottom shape of the container, there is no preparation period or cost for manufacturing such a member, and an external electrode, a dielectric member, etc. The number of work to assemble is also reduced, and the commercial production efficiency is greatly improved.

It is the schematic for demonstrating the structure of the film forming apparatus 100. It is the schematic for demonstrating the preferable size of the recess 22a. It is the schematic for demonstrating the preferable depth of the recess 22a. It is the schematic for demonstrating the structure of the film forming apparatus 200. It is the schematic for demonstrating the preferable form of the fixing member 30. Only the relationship between the fixing member 30 and the dielectric member 20 is shown in an enlarged manner, and other members are omitted. It is a schematic diagram for demonstrating the form in which the plastic container 1 is installed in the film forming apparatus 100 in the film forming system. The configuration around the upper part of the body and the mouth of the plastic container 1 is omitted. It is the schematic for demonstrating the preferable size of the recess 22a in a film forming system. It is a schematic diagram for demonstrating the preferable relationship between the ground contact diameter of a plastic container 1 and the diameter of a recess 22a in a film forming system. It is a figure for demonstrating the film formation condition which concerns on Comparative Example 1. It is a figure for demonstrating the film formation condition which concerns on Example 1. FIG.

1. 1. Film forming apparatus (first embodiment)
FIG. 1 schematically shows the configuration of the film forming apparatus 100. The film forming apparatus 100 is an apparatus for forming a carbon film on the inner surface of the plastic container 1 by generating plasma while supplying a raw material gas to the inside of the plastic container 1. The film forming apparatus 100 has a bottomed tubular external electrode 10 having a side portion 11 and a bottom portion 12, and a bottomed tubular dielectric having a bottomed tubular outer electrode 10 installed inside the external electrode 10 and having a side portion 21 and a bottom portion 22. It includes a body member 20 and. Here, one feature of the film forming apparatus 100 is that the upper surface of the bottom portion 22 of the dielectric member 20 has a recess 22a at a substantially center thereof.

1.1. The plastic container film forming apparatus 100 is an apparatus for forming a carbon film on the inner surface of the plastic container 1 by generating plasma while supplying a raw material gas to the inside of the plastic container 1. That is, the internal shape of the film forming apparatus 100 is determined according to the outer shape of the plastic container 1 to be film-formed. The plastic container 1 may be a plastic container having a bottom and a mouth.
The shape of the bottom of the plastic container 1 is not particularly limited. Various shapes can be adopted, such as those having a ground contact portion (legs) continuously or intermittently on the bottom surface, and those having a flat bottom surface (those without legs). In the film forming apparatus 100, since the recess 22a is provided at the bottom of the dielectric member 20 as described later, the bottom of the dielectric member 20 and the plastic container 1 are provided regardless of the shape of the bottom of the plastic container 1. A space can be provided between the center of the bottom and the center. Therefore, the concentration of plasma at the time of film formation can be suppressed, and the occurrence of excessive coloring at the bottom of the plastic container 10 can be suppressed.
The shape of the body of the plastic container 1 is also not particularly limited. Various shapes such as a circular, elliptical, and square (polygonal) cross-sectional shape of the body can be adopted. In particular, it is preferable that the cross-sectional shape of the body portion is circular.
The shape of the mouth portion of the plastic container 1 is not particularly limited, and the diameter may be reduced as compared with the body portion. In particular, the ratio of the inner diameter of the mouth to the inner diameter of the body (inner diameter of the mouth / inner diameter of the body) is preferably 0.35 or less, more preferably 0.30 or less, still more preferably 0.25 or less. The lower limit of the ratio (inner diameter of the mouth / inner diameter of the body) is preferably 0.15 or more, for example. In the case of the plastic container 1 having such an inner diameter ratio, the gas introduced into the container and the gas discharged from the inside of the container are formed by the chemical vapor deposition method on the inner surface of the container whose mouth has a smaller diameter than the body. The flow balance of the container is improved, and the thickness of the mouth, body, and bottom of the container tends to be uniform, which is an advantageous effect.
The volume of the plastic container 1 is also not particularly limited. For example, a plastic container having a volume of several tens of ml or more and 2 L or less, which is often used for general consumers, may be used, or a large plastic container of 3 L or more and 30 L or less, for example, for commercial use can be applied.
The material of the plastic container 1 is also not particularly limited. The plastic container 1 may be constructed of a general-purpose resin. Preferably, it is polyethylene terephthalate (PET) resin, polypropylene (PP) resin, cyclic polyolefin (CPO) resin or the like.

1.2. External electrode The external electrode 10 has a side portion 11 and a bottom portion 12, and has an internal shape corresponding to the plastic container 1 and the dielectric member 20. The structure and mechanism of the external electrode 10 made of a conductive material are known and are obvious to those skilled in the art. For example, the structure or mechanism as disclosed in Patent Documents 1 to 3 may be used.

1.3. Dielectric member By providing the dielectric member 20 between the external electrode 10 and the plastic container 1 in the film forming apparatus 100, abnormal discharge or the like during plasma film forming can be suppressed, and uneven film forming or the like can be suppressed. The film forming apparatus 100 is characterized by the structure of the bottom portion 22 of the dielectric member 20. That is, it is important that the dielectric member 20 is a bottomed tubular dielectric member having a side portion 21 and a bottom portion 22 and has a recess 22a substantially in the center of the upper surface of the bottom portion 22. In other words, the upper surface of the bottom portion 22 of the dielectric member 20 has a central portion recessed downward as compared with other portions. For example, as shown in FIG. 1, the upper surface of the bottom portion 22 of the dielectric member 20 has a recess 22a and a flat portion 22b.

The recess 22a may be formed by cutting a single plate-shaped dielectric from the dielectric member 22 to form a recess, or a plurality of dielectrics may be closely combined to form a recess. For example, a fixing member 30 made of a dielectric material described later and a plate-shaped dielectric material having a concave portion may be combined. In that case, the upper surface (top surface) of the fixing member 30 becomes the surface of the recess 22a.

The size of the recess 22a (the area ratio of the bottom portion 22 to the upper surface) is not particularly limited, but as shown in FIG. 2, the area of the entire upper surface of the bottom portion 22 of the dielectric member 20 (A) is as shown in FIG. The ratio ((a ₁ / A ₁ ) × 100%) of the area (a _{1 ) of the recess 22a to 1} = a ₁ + a ₂ ) is preferably 0.2% or more and 10% or less. The lower limit is more preferably 0.5% or more, further preferably 0.8% or more, and the upper limit is more preferably 8% or less, still more preferably 5% or less. By setting the size of the recess 22a within such a range, it is possible to further reduce the color unevenness of the carbon film at the bottom of the plastic container during film formation.

The shape of the recess 22a in a top view is not particularly limited. A shape substantially similar to the cross-sectional shape of the body of the plastic container 1 (horizontal cross-sectional shape of the side portion 21 of the dielectric member 20) is preferable. That is, when the cross-sectional shape of the body of the plastic container 1 is circular, it is preferable that the shape of the recess 22a in the top view is also circular. The diameter of the recess 22a in the top view (when the shape of the recess 22a in the top view is non-circular, the diameter when converted into a circle having the same area as the recess 22a) is preferably 3 mm or more and 30 mm or less. The lower limit is more preferably 5 mm or more, further preferably 8 mm or more, and the upper limit is more preferably 20 mm or less, still more preferably 15 mm or less. By setting the diameter of the recess 22a within such a range, it is possible to further reduce the color unevenness of the carbon film at the bottom of the plastic container during film formation.

The depth of the recess 22a (the distance from the reference height to the surface of the recess 22a with the flat surface 22b of the bottom 22 as the reference height) is not particularly limited.
As shown in FIG. 3, when viewed from the side, the distance L1 between the upper surface of the bottom portion 22 of the dielectric member 20 and the surface of the recess 22a is preferably 1 mm or more and 5 mm or less. The lower limit is more preferably 1.5 mm or more, and the upper limit is more preferably 3 mm or less. When the surface of the recess 22a is not substantially flat, it means the distance to the upper end of the deepest portion of the recess 22a.
By setting the depth of the recess 22a within such a range, it is possible to further reduce the color unevenness of the carbon film at the bottom of the plastic container during film formation.

The upper surface of the bottom portion 22 of the dielectric member 20 is preferably formed by a flat portion 22b except for the recess 22a. The lower surface of the bottom portion 22 of the dielectric member 20 corresponds to the shape of the upper surface of the bottom portion 12 of the external electrode 10.

The side portion 21 of the dielectric member 20 corresponds to the shape of the side portion 11 of the external electrode 10 (the shape of the body portion of the plastic container 1). That is, the shape may be such that the inner surface of the side portion 11 of the external electrode 10 and the outer surface of the side portion 21 of the dielectric member 20 substantially coincide with each other. The shape of the dielectric member 20 can be the same as the conventional one except for the shape of the bottom portion 22.

The thickness of the dielectric member 20 is not particularly limited. For example, the thickness of the bottom portion 22 (thickness of the flat portion 22b excluding the recess 22a) is preferably 1 mm or more and 20 mm or less. The lower limit is more preferably 3 mm or more, and the upper limit is more preferably 10 mm or less. Further, the thickness of the side portion 21 is preferably 1 mm or more and 20 mm or less. The lower limit is more preferably 3 mm or more, and the upper limit is more preferably 10 mm or less. By setting the thickness of the dielectric member 20 within such a range, it is possible to obtain sufficient strength in terms of processing, combination, repeated use, etc. of the dielectric member, and further reduce film formation unevenness during film formation. it can.

The dielectric member 20 is preferably made of a dielectric having a relative permittivity of 1.5 or more and 20 or less. The lower limit is more preferably 2 or more, and the upper limit is more preferably 10 or less. Specific examples of the dielectric material that can form the dielectric member 20 include fluororesins such as polytetrafluoroethylene, polychlorotrifluoroethylene, and polyvinylidene fluoride, polyetheretherketone, polyphenylene sulfide, polyetherimide, and polyallylate. Examples thereof include engineering plastic resins such as, and ceramics such as alumina and glass. In particular, the dielectric member 20 is preferably made of a fluororesin from the viewpoint of chemical resistance, and more preferably made of a polymer or copolymer having a polytetrafluoroethylene skeleton having high heat resistance and low friction. By using such a material for the dielectric member 20, it is possible to further reduce the color unevenness of the carbon film at the bottom of the plastic container during film formation.

1.4. Other Members Although it depends on the volume of the plastic container 1, the film forming apparatus 100 preferably includes an internal electrode that is inserted into the inside from the mouth of the plastic container 1. The internal electrode can also function as a supply means for supplying the raw material gas to the inside of the plastic container 1. The structure and mechanism of the internal electrode are known and are obvious to those skilled in the art. For example, the structure or mechanism as disclosed in Patent Documents 1 to 3 may be used. The film forming apparatus 100 can have the same configuration as the conventional film forming apparatus except for the structure of the bottom portion 22 of the dielectric member 20. The film forming apparatus 100 naturally includes a normal member as a member other than the above. Since the members required for plasma film formation are obvious to those skilled in the art (Patent Documents 1 to 3 and the like), further description will be omitted here.

As described above, in the film forming apparatus 100, the recess 22a is provided in the center of the upper surface of the bottom 22 of the dielectric member 20, and is between the upper surface of the bottom 22 of the dielectric member 20 and the center of the bottom of the plastic container 1. There is an interval in. As a result, it is possible to suppress the concentration of plasma during plasma film formation, and it is possible to suppress film formation unevenness and color darkening at the bottom of the plastic container 1.

2. Film forming apparatus (second embodiment)
FIG. 4 schematically shows the configuration of the film forming apparatus 200. In the film forming apparatus 200, the same members as those of the film forming apparatus 100 are designated by the same reference numerals. As shown in FIG. 4, in the film forming apparatus 200, a fixing member 30 made of a dielectric is provided substantially in the center of the upper surface of the bottom portion 22 of the dielectric member 20, and the upper surface (top surface) of the fixing member 30 is a recess 22a. It constitutes at least a part of the surface of the.

The fixing member 30 fixes the external electrode 10 and the dielectric member 20. Even without the fixing member 30, it is possible to fit and fix the dielectric member 20 inside the external electrode 10. However, considering the ease of assembling the device, the ease of positioning, the suppression of rattling, and the like, it is preferable to fix the external electrode 10 and the dielectric member 20 by the fixing member 30. In particular, as shown in FIG. 4, the fixing member 30 has a head on the dielectric member side and a screw portion on the external electrode side, and the dielectric member 20 and the external electrode 10 are connected to each other via the fixing member 30. It is preferable that they are fixed to each other.

As described above, the fixing member 30 constitutes at least a part of the surface of the recess 22a. In other words, as shown enlarged in FIG. 5, the upper end of the fixing member 30 exists at a position lower than the flat portion 22b of the bottom portion 22 of the dielectric member 20. If the head (screw head) of the fixing member 30 is too large, the head (screw head) protrudes from the bottom surface 22 of the dielectric member 20, and the recess 22a cannot be properly formed. From this point of view, the fixing member 30 is preferably a low-head screw, for example. Specifically, the thickness of the head (screw head) is preferably 1 mm or more and 5 mm or less, and the upper limit is more preferably 3 mm or less. On the other hand, the length of the screw portion of the fixing member 30 is not particularly limited. It may be appropriately determined according to the thickness of the dielectric member 20 and the like.

The fixing member 30 is preferably made of a dielectric having a relative permittivity of 1.5 or more and 20 or less. The lower limit is more preferably 2 or more, further preferably 3 or more, and the upper limit is more preferably 10 or less. The fixing member 30 may be made of the same material as the dielectric member 20, or may be made of a different material. In particular, the fixing member 30 is preferably made of a material having good machinability and high mechanical strength. Specific examples of the dielectric material that can form the fixing member 30 include engineering plastic resins such as polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polyetherimide (PEI), and polyarylate (PAR). .. In particular, the fixing member 30 is preferably made of PEEK resin from the viewpoint of high heat resistance, mechanical strength, and electrical insulation. As a result, the fixing member 30 exhibits the same function as the dielectric member 20, and sufficient mechanical strength can be ensured for the fixing member 30.

As described above, also in the film forming apparatus 200, the recess 22a including the fixing member 30 is provided in the center of the upper surface of the bottom 22 of the dielectric member 20, and the upper surface of the fixing member 30 and the center of the bottom of the plastic container 1 are formed. There is an interval between them. As a result, it is possible to suppress the concentration of plasma during plasma film formation, and it is possible to suppress film formation unevenness and color darkening at the bottom of the plastic container 1.

3. 3. Film formation system As described above, a carbon film can be formed as a gas barrier film on the inner surface of the plastic container 1 by using the film forming devices 100 and 200 of the present disclosure. Here, according to the findings of the present inventors, by setting the distance between the upper surface of the bottom 22 of the dielectric member 20 and the bottom of the plastic container 1 within a predetermined range, the film is formed at the bottom of the plastic container 1 at the time of film formation. It is possible to further suppress film unevenness and the like.

Specifically, as shown in FIG. 6, in a system in which a plastic container 1 is installed inside the film forming apparatus 100 and 200 dielectric member 20 of the present disclosure to form a carbon film on the inner surface of the plastic container 1. _{The distance (L 2} ) between the lower surface of the bottom center of the plastic container 1 and the surface of the recess 22a at the bottom of the dielectric member 20 is preferably 3.0 mm or more and 25 mm or less. The lower limit is more preferably 5 mm or more, and the upper limit is more preferably 20 mm or less.
The “surface of the recess 22a” refers to the substantially horizontal bottom surface when the recess 22a has a substantially horizontal bottom surface as shown in FIG. When the recess 22a does not have a substantially horizontal bottom surface, the deepest portion of the recess 22a is referred to as the “surface of the recess 22a”. When the top surface of the fixing member 30 is the bottom surface of the recess 22a (see FIG. 10), the top surface of the fixing member 30 is the “surface of the recess 22a”.

Further, the preferable size of the recess 22a can be specified with reference to the ground contact diameter of the bottom of the plastic container 1. For example, as shown in FIG. 7 (A), when the central portion of the bottom of the plastic container 1 is substantially horizontal, the recess 22a may be made to have a size obtained by projecting the substantially horizontal portion or a size smaller than that. As shown in 7 (B), when the bottom of the plastic container 1 is recessed toward the container contents in a bowl shape or a substantially conical shape, the size is the projected horizontal position of half the height of the recess or more. It is preferable to make the size small.
Specifically, in the film forming system when the plastic container 1 is a cylindrical bottle, as shown in FIG. 8, the diameter (D ₂ ) of the recess 22a is set to the ground contact diameter of the plastic container 1 in the top view. It is preferably 2% or more and 40% or less of (D _1). The lower limit is more preferably 5% or more, further preferably 10% or more, and the upper limit is more preferably 30% or less, still more preferably 20% or less.
The ground contact diameter of the plastic container 1 is a case where a circle is drawn so as to connect at least three points where the flat plate and the bottom of the plastic container 1 are in contact with each other when the plastic container 1 is erected on a flat plate. The diameter of the circle.

In the film forming system, various conditions such as the plasma output (W) of plasma chemical vapor deposition and the flow velocity (sccm) of the raw material gas are not particularly limited. Regardless of the conditions, a certain effect can be ensured by the recess 22a. Although it depends on the volume of the plastic container 1, for example, when the volume of the plastic container 1 is several tens of ml or more and 2 L or less, the high frequency plasma output is preferably 100 W or more and 2000 W or less, and the flow velocity of the raw material gas is several tens of sccm or more. It is preferably about 200 sccm or less. When the volume of the plastic container 1 is 2 L or more and 30 L or less, the high frequency plasma output is preferably about 2000 W or more and about 5000 W or less, and the flow velocity of the raw material gas is preferably about 200 sccm or more and about 500 sccm or less.
Further, according to a new finding of the present inventors, when the container has a shape in which the mouth portion has a smaller diameter than the body portion, the ratio (sccm / ml) of the flow velocity (sccm) of the raw material gas to the volume (ml). ) Is 0.10 or less, it is easier to suppress the above-mentioned uneven film formation, and the ratio of the inner diameter of the mouth to the inner diameter of the body (inner diameter of the mouth / inner diameter of the body) of the plastic container 1 is 0. In the case of 25 or less, if the ratio of the gas flow velocity to the volume (sccm / ml) is 0.08 or less, it is effective in suppressing the above-mentioned film formation unevenness.

The procedure for forming a film in a film forming system is known as disclosed in Patent Documents 1 to 3 and the like. The general procedure is as follows, for example.
(1) A dielectric member 20 is installed in the external electrode 10 and the plastic container 1 is inserted.
(2) Exhaust the gas in the system by an exhaust means or the like to reach a predetermined degree of vacuum.
(3) While supplying the raw material gas from the internal electrode or the like into the plastic container 1, high-frequency power is applied to the external electrode 10 to generate plasma between the external electrode and the internal electrode.
(4) A carbon film is formed by ionizing the raw material gas with the generated plasma, chemically reacting it, and depositing it on the inner surface of the plastic container 1. The carbon film formed in this case may be any gas barrier film, and may be any of various carbon films such as a DLC film and an amorphous carbon film.
The thickness of the carbon film is preferably in the range of 5 nm or more and 200 nm or less, the lower limit is preferably 10 nm or more, and the upper limit is more preferably 100 nm or less, which can be selected according to the gas barrier property, transparency and color.

4. Manufacturing Method of Plastic Container The technical concept of the present disclosure can also be expressed as a manufacturing method of a plastic container. That is, it is a method of manufacturing a plastic container by installing a plastic container 1 inside the dielectric members 20 of the film forming apparatus 100 and 200 of the present disclosure and forming a carbon film on the inner surface of the plastic container 1. This is a manufacturing method in which the distance between the lower surface of the bottom center of the plastic container 1 and the surface of the recess 22a of the bottom portion 22 of the dielectric member 20 is 3.0 mm or more and 25 mm or less. Also in the manufacturing method of the present disclosure, it is preferable that the diameter of the recess 22a is 0.2% or more and 20% or less of the ground contact diameter of the plastic container 1 in the top view. The preferable conditions in the manufacturing method are as described in the above-mentioned film forming system, and detailed description thereof will be omitted here.

As described above, also in the film forming system and the manufacturing method of the present disclosure, by using the dielectric member 20 having the recess 22a in the bottom portion 22, the space between the upper surface of the fixing member 30 and the center of the bottom portion of the plastic container 1 is separated. Provided. As a result, it is possible to suppress the concentration of plasma during plasma film formation, and it is possible to suppress film formation unevenness and color darkening at the bottom of the plastic container 1.

Hereinafter, the film forming apparatus and the like of the present disclosure will be described in more detail while showing examples.

1. 1. Film formation conditions (Comparative Example 1, Example 1)
A plastic container is loaded in a combination of an external electrode 10 and a dielectric member 20 as shown in FIG. 4 with a fixing screw 30, and the inside of the container also serves as a gas supply member at a height of half the total height of the container. Electrodes were arranged and a diamond-like carbon film was formed on the entire inside of the container by a high-frequency plasma chemical vapor deposition method.
Polytetrafluoroethylene (PTFE, relative permittivity 2.1) was used for the dielectric member 20. Polyetheretherketone (PEEK, relative permittivity 3.3) was used as the fixing screw.
As the plastic container, a container made of polyethylene terephthalate resin having a volume of 1 L, an inner diameter of the mouth of 29 mm, an inner diameter of the body of 106 mm, and an inner diameter of the mouth / inner diameter of the body of 0.27 was used. The bottom of the container is grounded with five legs with a grounding diameter (D ₁ ) of 63 mm, the center of the bottom has a substantially horizontal portion with a diameter of about 40 mm, and the flat portion (22b) of the bottom of the dielectric member is the center of the bottom of the container. The bottom height to the part was 5.6 mm.
Plasma chemical vapor deposition was carried out using acetylene as the raw material gas under the conditions of a gas flow rate of 95 sccm, a ratio of the gas flow rate (sccm) to the container volume (ml) of 0.091, a high frequency of 13.56 MHz, and a plasma output of 1600 W.
Other conditions are shown in Table 1.

In Comparative Example 1, the dielectric member and the external electrode were fixed by using a screw having a general shape having a head diameter of 9.5 mm and a head thickness of 6 mm as shown in FIG. In Comparative Example 1, the screw head protruded upward from the center of the bottom of the dielectric member, and no recess was formed.
On the other hand, in Example 1, the dielectric member and the external electrode were fixed by using a low-head screw having a head diameter of 9.5 mm and a head thickness of 1.5 mm as shown in FIG. As a result, in Example 1, a recess having a depth of about 1.5 mm is formed in the center of the bottom of the dielectric member. The ratio of the recessed area to the total bottom surface area of the dielectric member (recessed area / total area, a1 / A1) was 1.0%, and the ratio of the recessed diameter to the ground contact diameter of the container was 15.0%.

(Reference example 1)
As disclosed in Patent Document 2, at the time of film formation, polytetrafluoroethylene (PTFE, relative permittivity 2.1), which is a dielectric, is used to form a shape corresponding to the bottom shape (outer shape) of the container. Reference Example 1 was a case where a member was produced and brought into close contact with the bottom of the container. Other conditions were the same as in Example 1 and Comparative Example 1.

2. Evaluation result (bottom color)
Coloring due to the carbon film was visually confirmed on the plastic container after the film formation. As a result, in the plastic containers obtained under the conditions of Comparative Example 1 and Reference Example 1, the color of the bottom was darker than that of the body, and a thick carbon film was formed on the bottom.
In Comparative Example 1, it is considered that the screw head protruded from the bottom of the dielectric member during film formation and plasma was concentrated there, resulting in uneven film formation. In particular, the color at the center of the bottom surface was local. It was dark. In addition, 300 film formations were performed, and color unevenness occurred in 3 of them, and the probability of occurrence of defects was 1.0%, which significantly reduced the manufacturing yield.
In Reference Example 1, it is considered that the plasma was concentrated on the lower side of the container due to the dielectric material in close contact with the bottom of the bottle, which was considered to have caused uneven film formation, and the entire bottom surface was darker than the body.
On the other hand, in the plastic container obtained under the condition of Example 1, there is almost no film formation unevenness between the bottom and the body, the bottom and the body have substantially the same color, and even if 2000 films are formed. No color unevenness occurred, and the probability of defect occurrence was 0.0%. It is probable that the above-mentioned plasma concentration could be suppressed by retracting the screw head downward during film formation.

(Gas barrier property)
Using an OX-TRAN2 / 61 machine manufactured by MOCON, the adapter head for the device was attached to the opening of the plastic container before and after film formation, and the oxygen permeability per container (oxygen permeability per container) under the condition of 23 ° C. and 50% relative humidity ( cc / pkg / 24h · atm) was measured.
As a result, Example 1, Comparative Example 1, and Reference Example 1 were all 0.003 cc / pkg / 24 h · atm. Further, since the container before the film formation was 0.06 cc / pkg / 24 h · atm, the improvement rate of the oxygen permeability by the film formation was 20 times.

The film forming apparatus of the present disclosure can be suitably used when forming a gas barrier carbon film on the inner surface of a plastic container. The plastic container manufactured by using the film forming apparatus of the present disclosure has excellent gas barrier properties, does not allow carbon dioxide and flavor components to escape, and is unlikely to cause oxidation of the contents. Therefore, it can be used in all fields such as containers for storing beverages and foods and containers for medical use. Furthermore, it is not necessary to manufacture or assemble a custom-made member for each bottom shape of the container, which is very effective in reducing costs and improving production efficiency.

1 Plastic container 10 External electrode 11 Side 12 Bottom 20 Dielectric member 21 Side 22 Bottom 22a Recess 22b Flat part 30 Fixing member 100, 200 Film deposition equipment

Claims (10)

A device that generates plasma while supplying raw material gas to the inside of a plastic container to form a carbon film on the inner surface of the plastic container.
With a bottomed tubular external electrode with sides and bottom,
A bottomed tubular dielectric member installed inside the external electrode and having a side portion and a bottom portion.
With
The upper surface of the bottom portion of the dielectric member has a recess substantially in the center thereof.
Film forming equipment. A fixing member made of a dielectric is provided at substantially the center of the upper surface of the bottom of the dielectric member.
The upper surface of the fixing member constitutes at least a part of the surface of the recess.
The film forming apparatus according to claim 1. The fixing member has a head on the dielectric member side and a screw portion on the external electrode side.
The dielectric member and the external electrode are fixed to each other via the fixing member.
The film forming apparatus according to claim 2. The fixing member is made of a dielectric having a relative permittivity of 1.5 or more and 20 or less.
The film forming apparatus according to claim 2 or 3. The dielectric member is made of a dielectric having a relative permittivity of 1.5 or more and 20 or less.
The film forming apparatus according to any one of claims 1 to 4. In top view, the ratio of the area of the recess to the total area of the top surface of the bottom of the dielectric member ((recess area / total area) × 100%) is 0.2% or more and 10% or less.
The film forming apparatus according to any one of claims 1 to 5. A system in which a plastic container is installed inside the dielectric member of the film forming apparatus according to any one of claims 1 to 6 to form a carbon film on the inner surface of the plastic container.
The distance between the lower surface of the center of the bottom of the plastic container and the surface of the concave portion of the bottom of the dielectric member shall be 3.0 mm or more and 25 mm or less.
Film formation system. In top view, the diameter of the recess is set to 2% or more and 40% or less of the ground contact diameter of the plastic container.
The film forming system according to claim 7. A method for manufacturing a plastic container by installing a plastic container inside the dielectric member of the film forming apparatus according to any one of claims 1 to 6 and forming a carbon film on the inner surface of the plastic container. And
The distance between the lower surface of the center of the bottom of the plastic container and the surface of the concave portion of the bottom of the dielectric member shall be 3.0 mm or more and 25 mm or less.
Production method. In top view, the diameter of the recess is set to 0.2% or more and 20% or less of the ground contact diameter of the plastic container.
The manufacturing method according to claim 9.

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