JP2007070734A - Plastic container coated with diamond-like carbon film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plastic container suitable as a container for oxygen-sensitive drinks or sparkling drinks, and a manufacturing apparatus capable of manufacturing such the plastic container. <P>SOLUTION: A DLC (diamond-like carbon) film having a thickness of 50-400 Å is formed on an inner surface of the plastic container. The DLC film can be formed using the manufacturing apparatus comprising an outer electrode located outside the plastic container 5, an inner electrode 11 located inside the plastic container 5, a pipe 12 through which a raw material gas of a carbon source is supplied to the depressurized plastic container and a high-frequency oscillator 9 for applying voltage between the outer electrode and the inner electrodes after the raw material gas is supplied to generate a plasma for forming a hard carbon film on the inner wall of the plastic container. The outer electrode has a bottom electrode 4 located along the bottom of the plastic container and a body electrode 3 located along a body of the plastic container. The upper edge of the bottom electrode is positioned below half the height of the plastic container. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus for producing a carbon film coated plastic container that can be used as a container for oxygen-sensitive beer, sparkling wine, wine, high fruit juice beverages, and the like.

  In general, plastic containers are widely used as filling containers in various fields such as foods and pharmaceuticals because they are easy to mold, lightweight, and low in cost.

  However, plastics, as is well known, have the property of permeating low molecular gases such as oxygen and carbon dioxide and the property of sorbing low molecular organic compounds. For this reason, a plastic container receives various restrictions about the use object and usage form compared with a glass container.

  For example, when a plastic container is used as a filled container for carbonated beverages such as beer or wine or wine, oxygen permeates the plastic and oxidizes the beverage over time, or carbon dioxide in the carbonated beverage permeates the plastic. The carbonated beverage may be exhausted because it is released to the outside of the container. Therefore, the plastic container is not suitable as a filling container for beverages that dislike oxidation or carbonated beverages.

  In addition, when a plastic container is used as a filling container for a beverage having a fragrance component such as orange juice, a fragrance component (for example, limonene of orange juice) which is a low molecular organic compound contained in the beverage is sorbed onto the plastic. Therefore, the balance of the composition of the aroma component of the beverage is lost, and the quality of the beverage is deteriorated. Therefore, the plastic container is not suitable as a filling container for beverages having aroma components.

  On the other hand, in recent years, especially the recycling of resources has been called out, and the collection of used containers has become a problem. When plastic containers are used as returnable containers, unlike glass containers, when plastic containers are left in the environment during collection, various low molecular organic compounds such as mold odors are sorbed on the plastics. End up. For this reason, conventionally, there have been limited examples in which plastic containers are used as returnable containers.

However, as described above, the plastic container has characteristics such as ease of molding, light weight, and low cost, so the plastic container can be used as a filling container for carbonated beverages and beverages having aroma components, and the purity. It is very convenient if it can be used as a filling container for a substance that is required, and as a returnable container.
JP-A-8-53117

As a container that can meet such demands, JP-A-8-53117 discloses a DLC (Diamond Like Carbon, hereinafter referred to as “Diamond Like Carbon”) film on the inner wall surface of a plastic container. A formed container and an apparatus for manufacturing such a container are disclosed. The DLC film is a hard carbon film called an i-carbon film or a hydrogenated amorphous carbon film (aC: H), which is an amorphous carbon film mainly composed of SP ³ bonds, and is very hard and insulating. It has excellent refraction properties and a high refractive index. By forming such a DLC film on the inner wall surface of a plastic container, a container that can be used as a returnable container can be obtained.

  An object of the present invention is to provide a DLC film-coated plastic container suitable as a container for oxygen-sensitive beverages and sparkling beverages, a manufacturing apparatus capable of manufacturing the same, and a manufacturing method thereof.

  An apparatus for manufacturing a DLC film-coated plastic container according to the present invention includes an outer electrode disposed outside a plastic container (5), an inner electrode (11) disposed inside the plastic container (5), and the plastic. A vacuum means for depressurizing the inside of the container (5), a gas supply means (12 or the like) for supplying a raw material gas of a carbon source into the plastic container (5) decompressed by the vacuum means, and the gas supply means ( 12), a DLC film is formed on the inner wall surface of the plastic container (5) by generating a plasma by applying a voltage between the outer electrode and the inner electrode (11). A first power source (4) disposed along a bottom of the plastic container (5), and the plastic container. And an upper end of the first electrode (4) is positioned below a central position of the upper and lower ends of the plastic container (5). The first electrode (4) and the second electrode (3) are capacitively coupled, and the output of the power supply device (8, 9) is the first electrode (4). ) Only.

  In this invention, since the outer electrode is divided into the first electrode (4) and the second electrode (3), it is possible to supply electric power suitable for each part.

  In the apparatus for manufacturing a DLC film-coated plastic container according to the present invention, the power supply device (8, 9) supplies lower power to the second electrode (3) than the first electrode (4) by capacitive coupling. Including the case of applying.

  In the present invention, the power supply device (8, 9) applies lower power to the second electrode (3) than the first electrode (4) by capacitive coupling, so the entire container (5) A DLC film having an appropriate thickness can be formed.

  In the apparatus for manufacturing a DLC film-coated plastic container according to the present invention, the outer electrode is provided above the second electrode (3) and is arranged along the shoulder (5) of the plastic container. The first electrode (4), the second electrode (3), and the third electrode (2) are capacitively coupled to each other at the upper and lower sides, and the power source The output of the device (8, 9) is preferably connected only to the first electrode (4).

  An apparatus for manufacturing a DLC film-coated plastic container according to the present invention includes an outer electrode disposed outside a plastic container (5), an inner electrode (11) disposed inside the plastic container (5), and the plastic. A vacuum means for depressurizing the inside of the container (5), a gas supply means (12 etc.) for supplying a raw material gas of a carbon source into the plastic container (5) depressurized by the vacuum means, and the gas supply means After supplying the source gas, a power supply device (8) that forms a DLC film on the inner wall surface of the plastic container (5) by generating a plasma by applying a voltage between the outer electrode and the inner electrode (11). 9), and the outer electrode includes a first electrode (4) disposed along the bottom of the plastic container (5) and a body of the plastic container (5). And a third electrode (2) disposed along the shoulder of the plastic container (5), and the first electrode (4). ), The second electrode (3), and the third electrode (2) are capacitively coupled to each other at the top and bottom, and the output of the power supply device (8, 9) is the first electrode ( 4) It is characterized by being connected only to.

  In this invention, since the outer electrode is divided into the first electrode (4), the second electrode (3), and the third electrode (2), it is possible to supply electric power suitable for each part. it can.

  In the apparatus for manufacturing a DLC film-coated plastic container according to the present invention, the power supply device (8, 9) supplies lower power to the second electrode (3) than the first electrode (4) by capacitive coupling. Including the case of applying.

  In the present invention, the power supply device (8, 9) applies lower power to the second electrode (3) than the first electrode (4) by capacitive coupling, so the entire container (5) A DLC film having an appropriate thickness can be formed.

  The DLC film-coated plastic container manufacturing apparatus according to the present invention further includes an outer electrode disposed outside the plastic container, an inner electrode disposed inside the plastic container, and a vacuum means for decompressing the plastic container. A gas supply means for supplying a source gas of a carbon source to the inside of the plastic container depressurized by the vacuum means, and a voltage between the outer electrode and the inner electrode after the supply of the source gas by the gas supply means. And generating a plasma to form a DLC film on the inner wall surface of the plastic container, and the outer electrode includes a first electrode disposed along the bottom of the plastic container, A second electrode disposed on the first electrode; and two or more electrodes disposed on the second electrode. , Each electrode is the outer electrode is respectively capacitively coupled with the upper and lower each other, and wherein the output of the power supply is connected only to the first electrode.

  In the method of manufacturing a DLC film-coated plastic container according to the present invention, the upper end of the first electrode constituting a part of the outer electrode is positioned below the central position of the upper and lower ends of the plastic container along the bottom of the plastic container. The first electrode is disposed outside the plastic container, and the second electrode constituting a part of the outer electrode is disposed outside the plastic container along the body of the plastic container. The first electrode and the second electrode are capacitively coupled, an inner electrode is disposed inside the plastic container, the inside of the plastic container is evacuated, and a carbon source material gas is placed inside the plastic container. By supplying and supplying power by connecting the output of the power supply device only to the first electrode, a voltage is applied between the first electrode, the second electrode, and the inner electrode. Is generated, characterized in that to form a DLC film on the inner wall surface of said plastic container.

  The method for manufacturing a DLC film-coated plastic container according to the present invention includes a case where lower power than that of the first electrode is applied to the second electrode by capacitive coupling.

  In the method of manufacturing a DLC film-coated plastic container according to the present invention, the first electrode constituting a part of the outer electrode is disposed outside the plastic container along the bottom of the plastic container, and the body of the plastic container is disposed. A second electrode constituting a part of the outer electrode along the shoulder of the plastic container and a third electrode constituting a part of the outer electrode along the shoulder of the plastic container. The first electrode, the second electrode, and the third electrode are capacitively coupled to each other at the upper and lower sides, an inner electrode is disposed inside the plastic container, and the inside of the plastic container is evacuated. After that, the raw material gas of the carbon source is supplied to the inside of the plastic container, and the first electrode and the second electrode are supplied by connecting the output of the power supply device only to the first electrode and supplying power. The To pole third electrode, and by applying a voltage to generate a plasma between said electrodes, characterized in that to form a DLC film on the inner wall surface of said plastic container.

  In the method of manufacturing a DLC film-coated plastic container according to the present invention, a first electrode constituting a part of the outer electrode is disposed outside the plastic container along the bottom of the plastic container, and the outer side of the plastic container is aligned. A second electrode constituting a part of the outer electrode is arranged on the upper part of the first electrode, and a part of the outer electrode is arranged on the upper part of the second electrode along the outside of the plastic container. The above electrodes are arranged, and the electrodes as the outer electrodes are capacitively coupled to each other on the upper and lower sides, the inner electrode is arranged inside the plastic container, the inside of the plastic container is evacuated, and then inside the plastic container A source gas of a carbon source is supplied, and an output of a power supply device is connected only to the first electrode to supply electric power, thereby providing an upper portion of the first electrode, the second electrode, and the second electrode. Arranged Serial 2 or more electrodes, and by applying a voltage to generate a plasma between said electrodes, characterized in that to form a DLC film on the inner wall surface of said plastic container.

  The method for manufacturing a DLC film-coated plastic container according to the present invention includes a case in which lower power than the first electrode is applied to an outer electrode other than the first electrode by capacitive coupling.

A DLC film-coated plastic container according to the present invention is a gas barrier plastic container having a DLC film formed on an inner wall surface, wherein the DLC film has a thickness of 50 to 400 mm and a density of 1.2 to 1.59 g / cm. It is characterized by being in the range of ³ . The DLC film-coated plastic container according to the present invention is a gas barrier plastic container in which a diamond-like carbon film is formed on the inner wall surface, and the diamond-like carbon film has a thickness of 50 to 400 mm and a density of 1.2. It may be in the range of ˜1.48 g / cm ³ .

  Furthermore, in the DLC film-coated plastic container according to the present invention, the hydrogen content of the DLC film is preferably in the range of 16 to 52 hydrogen atom%.

  In this invention, since the film thickness of the DLC film is in the range of 50 to 400 mm, it is possible to prevent the decrease in transparency due to the coloring of the DLC film while effectively reducing the oxygen permeability. Further, since the occurrence of cracks in the DLC film due to compressive stress is prevented, the oxygen barrier property can be prevented from being lowered, and the deposition time required for forming the DLC film is shortened, so that productivity is improved.

A DLC film-coated plastic container according to the present invention is a gas barrier plastic container having a DLC film formed on an inner wall surface, wherein the DLC film has a thickness of 232 to 432 mm and a density of 1.39 to 1.46 g / cm. It is characterized by being in the range of ³ .

A DLC film-coated plastic container according to the present invention is a gas barrier plastic container having a DLC film formed on an inner wall surface, and the DLC film thickness at the bottom of the gas barrier plastic container is 215 to 304 mm and the density is 1 It is characterized by being in the range of .48 to 1.59 g / cm ³ .

  The DLC film-coated plastic container according to the present invention is manufactured using the DLC film-coated plastic container manufacturing apparatus according to the present invention.

  In order to facilitate understanding of the present invention, reference numerals in the accompanying drawings are appended in parentheses, but the present invention is not limited to the illustrated embodiment.

  According to the first aspect of the invention, since the outer electrode is divided into the first electrode and the second electrode, it is possible to supply electric power suitable for each part.

  According to the fourth aspect of the invention, since the outer electrode is divided into the first electrode, the second electrode, and the third electrode, it is possible to supply electric power suitable for each part.

  According to the DLC film-coated plastic container of the present invention, since the film thickness of the DLC film is in the range of 50 to 400 mm, the transparency is reduced due to the coloring of the DLC film while effectively reducing the oxygen permeability. Can be prevented. Further, since the occurrence of cracks in the DLC film due to compressive stress is prevented, the oxygen barrier property can be prevented from being lowered, and the deposition time required for forming the DLC film is shortened, so that productivity is improved.

  Hereinafter, with reference to FIGS. 1-9, embodiment of the manufacturing apparatus of the DLC film | membrane and carbon film coating plastic container by this invention is described.

  FIG. 1 is a diagram showing an electrode configuration and the like of this apparatus. As shown in FIG. 1, this apparatus includes a base 1, a shoulder electrode 2 and a body electrode 3 attached to the base 1, and a bottom electrode 4 that is detachable from the body electrode 3. Prepare. As shown in FIG. 1, the shoulder electrode 2, the body electrode 3, and the bottom electrode 4 each have an inner wall surface that conforms to the outer shape of the plastic container 5, and the shoulder electrode 2 is the shoulder part of the plastic container 5. The body electrode 3 is disposed along the body of the plastic container 5, and the bottom electrode 4 is disposed along the bottom of the plastic container 5. The shoulder electrode 2, the trunk electrode 3, and the bottom electrode 4 constitute an outer electrode of the present apparatus.

  When the bottom electrode 4 is attached to the body electrode 3, the base 1, the shoulder electrode 2, the body electrode 3 and the bottom electrode 4 are in a state of being airtightly attached to each other. It functions as a vacuum chamber provided with a storage unit 10 for storage.

  As shown in FIG. 1, an insulator 6 is interposed between the shoulder electrode 2 and the body electrode 3 so that the shoulder electrode 2 and the body electrode 3 are electrically insulated from each other. An O-ring 7 is interposed between the body electrode 3 and the bottom electrode 4, and a slight gap is formed between the bottom electrode 4 and the body electrode 3 when the bottom electrode 4 is attached. The Thus, the two electrodes are electrically insulated from each other while ensuring the airtightness between the bottom electrode 4 and the body electrode 3.

  The storage unit 10 is provided with an internal electrode 11, and the internal electrode 11 is inserted into the plastic container 5 stored in the storage unit 10. The inner electrode 11 is electrically connected to the ground potential.

  The inner electrode 11 is formed in a hollow shape (cylindrical shape), and one blowing hole (not shown) for communicating the inside and outside of the inner electrode 11 is formed at the lower end thereof. Instead of providing the blowout hole at the lower end, a plurality of blowout holes (not shown) penetrating the inside and outside of the inner electrode 11 in the radial direction may be formed. A pipe 12 communicating with the inside of the inner electrode 11 is connected to the inner electrode 11, and the raw material gas fed into the inner electrode 11 through the pipe 12 is sent to the plastic container 5 through the blowout hole. It is configured so that it can be discharged into the inside. The pipe 12 is made of metal and has conductivity, and as shown in FIG. 1, the inner electrode 11 is connected to the ground potential using the pipe 12. Further, the inner electrode 11 is supported by a pipe line 12.

  As shown in FIG. 1, the output of a high-frequency oscillator 9 is connected to the bottom electrode 4 via a matching unit 8. The high frequency oscillator 9 generates a high frequency voltage with respect to the ground potential, whereby a high frequency voltage is applied between the inner electrode 11 and the bottom electrode 4.

  Next, a procedure for forming a DLC (Diamond Like Carbon) film on the inner wall surface of the plastic container 5 using this apparatus will be described.

  The plastic container 5 is set so that the bottom thereof is in contact with the inner surface of the bottom electrode 4, and the plastic container 5 is accommodated in the accommodating part 10 by raising the bottom electrode 4. At this time, the inner electrode 11 provided in the storage unit 10 is inserted into the plastic container 5 through the opening (upper end opening) of the plastic container 5.

  When the bottom electrode 4 rises to a predetermined position and the storage unit 10 is sealed, the outer periphery of the plastic container 5 is in contact with the shoulder electrode 2, the body electrode 3, and the inner surfaces of the bottom electrode 4. Next, the air in the storage unit 10 is exhausted through the exhaust port 1 </ b> A of the base 1 by a vacuum device (not shown). After the pressure in the storage unit 10 is reduced until the required degree of vacuum is reached, a raw material gas (for example, a carbon source gas such as aliphatic hydrocarbons or aromatic hydrocarbons) sent through the pipe 12 is supplied. Then, it is introduced into the plastic container 5 from the blowing hole of the inner electrode 11.

  After the concentration of the raw material gas reaches a predetermined value, a high frequency voltage is applied between the inner electrode 11 and the outer electrode by operating the high frequency oscillator 9, and plasma is generated in the plastic container 5. As a result, a DLC film is formed on the inner wall surface of the plastic container 5.

  That is, the DLC film is formed on the inner wall surface of the plastic container 5 by the plasma CVD method, and electrons accumulate on the inner wall surface of the outer electrode that is insulated by the plasma generated between the outer electrode and the inner electrode 11. Thus, a predetermined potential drop occurs.

  As a result, hydrocarbon carbon and hydrogen, which are source gases present in the plasma, are each ionized positively, and randomly collide with the inner wall surface of the plastic container 5 extending along the inner wall surface of the outer electrode. A hard carbon film made of extremely dense DLC is formed on the inner wall surface of the plastic container 5 by bonding between atoms, bonding between carbon atoms and hydrogen atoms, and separation of the hydrogen atoms once bonded (sputtering effect).

  As described above, the output terminal of the high-frequency oscillator 9 is connected to only the bottom electrode 4 via the matching unit 8. Further, a gap is formed between the bottom electrode 4 and the body electrode 3, and the bottom electrode 4 and the body electrode 3 are electrically insulated from each other. Further, an insulator 6 is interposed between the trunk electrode 3 and the shoulder electrode 2, and the trunk electrode 3 and the shoulder electrode 2 are electrically insulated from each other. Therefore, the high frequency power applied to the trunk electrode 3 and the shoulder electrode 2 is smaller than the high frequency power applied to the bottom electrode 4. However, since the bottom electrode 4 and the body electrode 3 and between the body electrode 3 and the shoulder electrode 2 are capacitively coupled through the respective gaps, the body electrode 3 and the shoulder electrode A certain amount of high-frequency power is also applied to 2.

  In general, the bottom of a plastic container such as a bottle has a complicated shape, and it is difficult to form a DLC film with a sufficient thickness. In addition, since the bottom portion is insufficiently stretched in production, the gas barrier property of the plastic itself is lowered at the bottom portion. For this reason, even after the DLC film is formed, the gas barrier property at the bottom of the container tends to be low.

  According to an experiment by the inventors of the present invention, when a plastic bottle is used as a plastic container and the same high frequency power is applied to the entire outer electrode corresponding to the shoulder electrode 2, the trunk electrode 3, and the bottom electrode 4, The DLC film was thickly coated from the mouth part of the plastic bottle to the shoulder part, the body part was thinner than this, and the thickness of the bottom part was extremely thin. In this case, as described above, since the gas barrier property of the plastic itself is low at the bottom, the gas barrier property of the entire bottle is greatly reduced. If an attempt is made to obtain a sufficient thickness, it takes 20 to 30 seconds as the time required for coating, which increases the production cost. Further, the DLC film is easily peeled off at the portion where the DLC film is formed thick, and when the coating time is increased or the high-frequency power is increased, the bottle is often deformed, which is a practical problem. As the high frequency power to be applied, about 400 to 500 W was appropriate power.

  Further, the adhesion of the DLC film to the inner wall surface of the container was insufficient, and the DLC film was not dense enough.

  Therefore, when uniform high frequency power is applied to the entire outer electrode, the gas barrier property can be improved only about 2 to 6 times that of the original plastic bottle.

  On the other hand, according to the manufacturing apparatus of the above embodiment, since a high frequency power larger than that of the trunk and shoulder can be applied to the bottom of the plastic container, a DLC film having a uniform thickness is formed on the entire bottle. Further, it is possible to form a thicker DLC film at the bottom where the gas barrier property of the plastic itself is low. Therefore, the gas barrier property as the whole container can be improved effectively. In the above embodiment, the applied power can be increased to 1200 to 1400 W, and thus the manufacturing cost can be reduced by shortening the coating time.

  Further, in the above-described embodiment, sufficient high-frequency power can be applied to the bottom while suppressing high-frequency power at the mouth and shoulder of the container. Therefore, the plastic container is dense and suppresses deformation of the plastic container. A DLC film having good adhesion to the inner wall surface can be obtained.

  In the above embodiment, the shoulder electrode 2, the body electrode 3 and the bottom electrode 4 are configured to be completely insulated in terms of direct current, but the electrodes are connected to each other by a resistive or capacitive element or the like. You may make it do. In short, it is only necessary to be able to apply a high-frequency power having a required magnitude according to each part of the container. For example, the shoulder electrode 2, the trunk electrode 3, and the bottom electrode 4 are separately provided. A plurality of high-frequency oscillators may be prepared so that high-frequency power is applied to them, or the output of a single high-frequency oscillator may be connected to each electrode via a plurality of matching devices.

  Although the case where the outer electrode is divided into three parts is illustrated in the above embodiment, the outer electrode may be divided into two parts, or may be divided into four or more parts.

  In the above embodiment, a container having a shape that makes it difficult to form a DLC film on the bottom has been described. However, by adjusting the distribution of high-frequency power to be applied according to the shape of the container, a good DLC can be obtained throughout the container. A film can be formed.

  According to the manufacturing apparatus of the present invention, a plastic container suitable as a returnable container can be manufactured. However, the plastic container manufactured by the present apparatus can be used for one-way use (not collected but disposable by filling the contents once. (Use).

Example 1
Next, conditions and evaluation results when a DLC film is formed on the inner wall surface of a 500 ml PET bottle using the above apparatus will be described.

  FIG. 2 shows the plasma CVD conditions and the dimensions of the PET bottle, and FIG. 3 shows a bottle evaluation method in which a DLC film is formed on the inner wall surface. FIG. 4 shows film forming conditions and evaluation results when toluene is used as the source gas, and FIG. 5 shows film forming conditions and evaluation results when acetylene is used as the source gas.

  In the table of “Plastic bottle dimensions” in FIG. 2B, “bottom / shoulder + body + bottom” is the ratio of the portion where the bottom electrode 4 is opposed to the total height of the bottle, that is, “ The value obtained by dividing “the length from the bottom of the bottle to the upper end of the bottom electrode 4” by “the height of the bottle (the length from the bottom of the bottle to the upper end)” is shown as a percentage.

  In the table of “Plastic bottle dimensions”, the columns “700 ml PET bottle” and “500 ml PP (polypropylene) bottle” have the same dimensions and bottoms as the 500 ml PET bottle for each type of bottle prepared as an experiment target. The part of the electrode is shown. 4 and 5 show only film forming conditions and evaluation results in a 500 ml PET bottle.

  In “(7) Discharge method of external electrode” in FIG. 2A, “1 overall” means that the shoulder electrode 2, the trunk electrode 3 and the bottom electrode 4 are electrically short-circuited, and these electrodes are simultaneously the same. The case where the high frequency power of is applied is shown. “Two body / bottom” electrically short-circuits the body electrode 3 and the bottom electrode 4 while the shoulder electrode 2 is insulated from the body electrode 3 with respect to the body electrode 3 and the bottom electrode 4. The case where the same high frequency power is applied simultaneously is shown. “3 bottom” is a method corresponding to the present invention, and shows a case where high frequency power is applied only to the bottom electrode 4 in a state where the shoulder electrode 2, the body electrode 3 and the bottom electrode 4 are electrically insulated from each other. . These discharge methods are described in the “Discharge method” column shown in FIGS.

  In “(1) Evaluation by appearance” and “(2) Deformation of container” in FIG. 3, “◯” represents the best state, and “×” represents the worst state. These evaluation results are described in predetermined columns of the tables shown in FIGS.

-Example 2-
Next, with reference to FIG. 6, conditions and evaluation results when a DLC film thinner than Example 1 is formed on the inner wall surface of a 500 ml PET bottle by the above apparatus will be described. In the second embodiment, the film thickness of the DLC film to be formed is reduced by setting the plasma time to a relatively short time.

  The plasma conditions of Experiment Nos. 1 to 6 will be described below. Acetylene was used as the source gas, and a method of applying high frequency power to the bottom electrode 4 was used as a discharge method. That is, high-frequency power was applied only to the bottom electrode 4 in a state where the shoulder electrode 2, the body electrode 3 and the bottom electrode 4 were electrically insulated from each other. The high frequency power is 1300 W, the degree of vacuum is 0.05 torr (6.66 Pa), and the gas flow rate is 31 cc / min. Note that Experiment No. 1 is a PET bottle on which no DLC film is formed.

  FIG. 6 shows the plasma time, the film thickness of the DLC film, and the oxygen permeability of Experiment Nos. 1-6. Fig.7 (a) and FIG.7 (b) have shown the shape of PET bottle.

  The height of the PET bottle 100 shown in FIG. 7, that is, the length A from the bottom to the upper end of the PET bottle 100 is 207 mm. The dimensions of other parts shown in FIG. 7 are B = 68.5 mm, C = 35.4 mm, D = 88 mm, E = 2 mm, F = 22.43 mm, G = 24.94 mm, H = 33 mm, J = 67. 0.7 mm, K = 26.16 mm, L = 66.5 mm, M = 21.4 mm, and N = 46 mm. The thickness of the wall surface of the PET bottle 100 is 0.4 mm.

  In the numerical value in the column of the film thickness in FIG. 6, the film thickness of the DLC film at the shoulder, trunk, and bottom of the PET bottle 100 is measured, and the film thickness of the DLC film is between the minimum value and the maximum value. It is shown as a range.

  As shown in FIG. 6, in the PET bottle of Experiment No. 1 in which no DLC film is formed, the oxygen permeability is 0.033 ml / day / container, whereas a DLC film having a film thickness of 50 to 75 mm is formed. In the PET bottle of Experiment No. 2, the oxygen permeability per container (PET bottle) is 0.008 ml / day. Thus, by forming a thin DLC film of about 50 to 75 mm, the oxygen permeability can be reduced to about 1/4. In addition, as shown in FIG. 6, in the PET bottles of experiment numbers 3 to 6 having a larger DLC film thickness, the oxygen permeability is further reduced. Thus, by forming a DLC film having a relatively small thickness of about 50 to 400 mm, the oxygen permeability can be effectively reduced.

  When the thin DLC film is formed on the inner wall surface of the PET bottle as in Experiment Nos. 2 to 6, there are the following advantages. First of all, the DLC film is colored slightly yellow. As the film thickness increases, the color gradually becomes black and the transparency of the container decreases. However, the transparency of the container can be improved by setting the thickness of the DLC film thin. In addition, when the film thickness of the DLC film increases, a large compressive stress acts on the DLC film and cracks occur in the DLC film, resulting in a problem that the oxygen barrier property deteriorates. However, the DLC film should be formed thin as described above. Thus, such a problem can be avoided. Furthermore, when the film thickness is set to be thin, the deposition time necessary for forming the film thickness is shortened, so that productivity is improved.

  The oxygen permeability shown in FIG. 6 was measured under the conditions of 22 ° C. and 60% RH using an Oxtran manufactured by Modern Control. The film thickness of the DLC film was measured using a tentacle type alpha-step500 stylus step meter.

-Example 3-
Hereinafter, the density of the DLC film formed on the inner wall surface of a 500 ml PET bottle using the above apparatus will be described with reference to FIG.

  The plasma conditions in the PET bottles with the experiment numbers 7 to 10 will be described below. Acetylene was used as the source gas, and a method of applying high frequency power to the bottom electrode 4 was used as a discharge method. That is, high-frequency power was applied only to the bottom electrode 4 in a state where the shoulder electrode 2, the body electrode 3 and the bottom electrode 4 were electrically insulated from each other. The degree of vacuum is 0.05 torr (6.66 Pa), the gas flow rate is 31 cc / min, and the plasma time is 8 seconds.

  FIG. 8 shows the density measurement results. In the “discharge method” column in FIG. 8, “whole” means that the shoulder electrode 2, the body electrode 3 and the bottom electrode 4 are electrically short-circuited and the same high-frequency power is simultaneously applied to these electrodes. Shown (experiment numbers 7 and 8). “Bottom” indicates that high-frequency power is applied only to the bottom electrode 4 in a state where the shoulder electrode 2, the body electrode 3 and the bottom electrode 4 are electrically insulated from each other (experiment numbers 9 and 10).

  The column of “high frequency applied voltage” indicates the high frequency power applied in each experiment number. FIG. 8 shows the thickness of the DLC film, the volume of the DLC film, the weight of the DLC film, and the density of the DLC film for the shoulder, trunk and bottom of the PET bottle of each experiment number. This corresponds to the display of “shoulder”, “torso”, and “bottom” in the “container part” column.

  In addition, the oxygen permeability shown in FIG. 8 was measured on the conditions of 22 degreeC and 60% RH using Oxtran made from Modern Control. The film thickness of the DLC film was measured with a stylus type step meter of Alpha-step 500 of Tenchol. The surface area of the PET bottle was calculated by CAD from the drawing of the PET bottle.

  In measuring the weight of the DLC film, the PET bottle 100 was divided into a shoulder, a trunk and a bottom. Next, each of these parts was immersed in a 4% NaOH aqueous solution in a beaker and reacted at room temperature for about 10-12 hours to peel off the DLC film. This solution was filtered through a polytetrafluoroethylene-made millipore filter (pore size: 0.5 μm), dried at 105 ° C., and the weight was measured together with the millipore filter. The weight of the peeled DLC film was determined by subtracting the weight of the Millipore filter before being used for filtration from this weight. In addition, since the NaOH solution has residues as impurities, the blank value of the NaOH solution was also obtained to correct the weight of the DLC film.

  The density of the DLC film was calculated from the following formula (1).

(Expression 1) Density = weight / (surface area × thickness) (1)

As shown in FIG. 8, the density of the DLC film was not clearly different depending on the discharge method, the magnitude of the high frequency applied power, or the site of the PET bottle, but the density range of the DLC film was 1.2 to It was 2.3 g / cm ³ .

Example 4
Hereinafter, the hydrogen content of the DLC film formed on the inner wall surface of a 500 ml PET bottle using the above apparatus will be described with reference to FIG.

  In Experiment Nos. 11 and 12, a glass substrate (length: 23 mm, width: 19 mm, thickness: 0.5 mm) was attached to a predetermined region of each of the shoulder, the trunk, and the bottom. Since PET contains hydrogen and causes an error in the measurement of the hydrogen content, a glass substrate is used. The glass substrate is attached via a metal plug attached to the outer electrode.

  In FIG. 7, the symbol “P” represents the upper region provided on the shoulder, the symbol “Q” represents the middle region provided on the trunk, and the symbol “R” represents the lower region provided on the bottom. . The lower end of the upper region P is 125 mm upward from the bottom of the PET bottle, and the upper end of the upper region P is 144 mm upward from the bottom of the PET bottle. The lower end of the middle region Q is 65 mm upward from the bottom of the PET bottle, and the upper end of the middle region Q is 84 mm upward from the bottom of the PET bottle. The lower end of the lower region R is 11 mm upward from the bottom of the PET bottle, and the upper end of the lower region R is 30 mm upward from the bottom of the PET bottle.

  As the plasma conditions, in both experiment numbers 11 and 12, acetylene was used as a source gas, and both were bottom discharges, that is, the bottom part in the state where the shoulder electrode 2, the trunk electrode 3 and the bottom electrode 4 were electrically insulated from each other. High frequency power is applied only to the electrode 4. The degree of vacuum is 0.05 torr (6.66 Pa), and the gas flow rate is 31 cc / min. In Experiment No. 11, the high frequency applied power is 800 W, and in Experiment No. 12, the high frequency applied power is 1200 W.

  In FIG. 9, the hydrogen content of the DLC film formed on the glass substrate provided in the upper region P, the middle region Q, and the lower region R in each PET bottle is shown. The indicated “upper”, “middle”, and “lower” indications represent the upper region P, the middle region Q, and the lower region R, respectively.

  As shown in FIG. 8, since the density of the DLC film varies between 1.22 and 2.30, the density of the DLC film is 1.2, 1.8, and 2.3, respectively. The hydrogen content is measured.

  For measurement of the hydrogen content, Shimadzu IBA-9900EREA (elastic recoil detection analysis; elastic recoil detection method) was used to measure the hydrogen concentration% (ratio of the number of hydrogen atoms) in the DLC film.

  As shown in FIG. 9, the hydrogen content increases when the high frequency applied power is large (experiment number 12). There is also a tendency for the hydrogen content to decrease slightly with increasing density.

  In the above embodiment, plasma is generated by applying high frequency power to form the DLC film, but the method of forming the DLC film is not limited to the method of the above embodiment. For example, the DLC film may be formed by generating plasma by microwave discharge.

  The DLC film of the present invention can also be applied to plastic containers made of materials other than PET or PP. Moreover, it can also be used for uses other than a container.

  In this specification, the “carbon film-coated plastic container” means a plastic container in which a DLC film is formed.

The figure which shows one Embodiment of the manufacturing apparatus by this invention. It is a figure which shows the conditions of plasma CVD, the dimension of a plastic bottle, etc., (a) is a figure which shows the conditions of plasma CVD, (b) is a figure which shows the dimension of a plastic bottle. The figure which shows the evaluation method of the 500 ml PET bottle in which the DLC film was formed. The figure which shows the evaluation result of the 500 ml PET bottle which formed DLC film using toluene as source gas. The figure which shows the evaluation result of the 500 ml PET bottle which formed the DLC film | membrane using acetylene as source gas. The figure which shows the film-forming conditions, film thickness, and oxygen permeability of the DLC film in the bottles of experiment numbers 1-6. It is a figure which shows the shape of a PET bottle, (a) is a front view, (b) is the bottom view seen from the BB line direction in (a). The figure which shows the film-forming conditions, density, etc. of the DLC film in the bottles of experiment numbers 7-10. The figure which shows the film-forming conditions, hydrogen content, etc. of the DLC film in the bottles of the experiment numbers 11 and 12.

Explanation of symbols

2 Shoulder electrode 3 Body electrode 4 Bottom electrode 5 Plastic container 8 Matching device 9 High frequency oscillator 11 Inner electrode 12 Pipe line 100 PET bottle

Claims (17)

  An outer electrode arranged outside the plastic container, an inner electrode arranged inside the plastic container, a vacuum means for depressurizing the inside of the plastic container, and carbon inside the plastic container depressurized by the vacuum means A gas supply means for supplying a source gas of the source; and after supply of the source gas by the gas supply means, a voltage is applied between the outer electrode and the inner electrode to generate plasma, thereby generating an inside of the plastic container. A power supply device that forms a diamond-like carbon film on the wall surface, and the outer electrode is disposed along the first electrode disposed along the bottom of the plastic container and along the trunk of the plastic container. A second electrode, and an upper end of the first electrode is positioned below a center position of the upper and lower ends of the plastic container. And the first electrode and the second electrode are capacitively coupled, and the output of the power supply device is connected only to the first electrode. Equipment for manufacturing diamond-like carbon film-coated plastic containers.   The said power supply device applies the electric power lower than the said 1st electrode to the said 2nd electrode by capacitive coupling, The manufacturing apparatus of the diamond-like carbon film coating plastic container of Claim 1 characterized by the above-mentioned.   The outer electrode includes a third electrode provided above the second electrode and disposed along a shoulder of the plastic container, and includes the first electrode, the second electrode, and the third electrode. 3. The diamond-like carbon film according to claim 1, wherein upper and lower electrodes are capacitively coupled to each other and an output of the power supply device is connected only to the first electrode. 4. Manufacturing equipment for coated plastic containers.   An outer electrode arranged outside the plastic container, an inner electrode arranged inside the plastic container, a vacuum means for depressurizing the inside of the plastic container, and carbon inside the plastic container depressurized by the vacuum means A gas supply means for supplying a source gas of the source; and after supply of the source gas by the gas supply means, a voltage is applied between the outer electrode and the inner electrode to generate plasma, thereby generating an inside of the plastic container. A power supply device that forms a diamond-like carbon film on the wall surface, and the outer electrode is disposed along the first electrode disposed along the bottom of the plastic container and along the trunk of the plastic container. A second electrode and a third electrode disposed along a shoulder of the plastic container, and the first electrode The diamond-like carbon, wherein the second electrode and the third electrode are capacitively coupled to each other at the top and bottom, and the output of the power supply device is connected only to the first electrode Film coating plastic container manufacturing equipment.   The said power supply device applies the electric power lower than the said 1st electrode to the said 2nd electrode by capacitive coupling, The manufacturing apparatus of the diamond-like carbon film coating plastic container of Claim 4 characterized by the above-mentioned.   An outer electrode arranged outside the plastic container, an inner electrode arranged inside the plastic container, a vacuum means for depressurizing the inside of the plastic container, and carbon inside the plastic container depressurized by the vacuum means A gas supply means for supplying a source gas of the source; and after supply of the source gas by the gas supply means, a voltage is applied between the outer electrode and the inner electrode to generate plasma, thereby generating an inside of the plastic container. A power supply device for forming a diamond-like carbon film on a wall surface, wherein the outer electrode includes a first electrode disposed along a bottom portion of the plastic container, and a first electrode disposed on an upper portion of the first electrode. 2 electrodes, and two or more electrodes disposed on top of the second electrode, and each of the electrodes that are the outer electrodes is above and below each other Has been amount bond and the power supply output apparatus for producing diamond-like carbon film coating plastic containers, characterized in that is connected only to the first electrode of.   The first electrode is placed outside the plastic container so that the upper end of the first electrode constituting a part of the outer electrode is positioned below the center position of the upper and lower ends of the plastic container along the bottom of the plastic container. A second electrode constituting a part of the outer electrode along the body portion of the plastic container is disposed outside the plastic container, and the first electrode and the second electrode are capacitive The inner electrode is disposed inside the plastic container, the inside of the plastic container is evacuated, and then the raw material gas of the carbon source is supplied to the inner side of the plastic container. Is connected to the first electrode, the second electrode, and the inner electrode to generate a plasma by applying a voltage to the inner wall of the plastic container. Diamond-like carbon film production method of coating plastic containers, characterized in that to form a Bon film.   8. The method for producing a diamond-like carbon film-coated plastic container according to claim 7, wherein a lower power than that of the first electrode is applied to the second electrode by capacitive coupling.   A first electrode that constitutes a part of the outer electrode along the bottom of the plastic container is disposed outside the plastic container, and a second electrode that constitutes a part of the outer electrode along the trunk of the plastic container Is disposed outside the plastic container, and a third electrode constituting a part of the outer electrode is disposed outside the plastic container along the shoulder of the plastic container, and the first electrode and the second electrode are disposed on the outside of the plastic container. And the third electrode are capacitively coupled to each other at the upper and lower sides, an inner electrode is disposed inside the plastic container, the interior of the plastic container is evacuated, and then a carbon source material gas is disposed inside the plastic container Between the first electrode, the second electrode and the third electrode, and the inner electrode by supplying power by connecting the output of the power supply device only to the first electrode. Apply voltage to the To generate Ma, diamond-like carbon film production method of coating plastic containers, characterized in that to form a diamond-like carbon film on the inner wall surface of said plastic container.   A first electrode constituting a part of the outer electrode along the bottom of the plastic container is disposed outside the plastic container, and a part of the outer electrode is disposed on the first electrode along the outer side of the plastic container. Each electrode that is an external electrode, and two or more electrodes that constitute a part of the external electrode are disposed on an upper portion of the second electrode along the outside of the plastic container. , The inner electrode is arranged inside the plastic container, the inside of the plastic container is evacuated, and then the carbon source material gas is supplied to the inside of the plastic container, and the first electrode The first electrode, the second electrode, the two or more electrodes disposed above the second electrode, and the inner electrode by connecting the output of the power supply device only to supply power Apply a voltage between the plasma Raises, diamond-like carbon film production method of coating plastic containers, characterized in that to form a diamond-like carbon film on the inner wall surface of said plastic container.   11. The method for producing a diamond-like carbon film-coated plastic container according to claim 9 or 10, wherein a lower power than that of the first electrode is applied to an outer electrode other than the first electrode by capacitive coupling. A gas barrier plastic container having a diamond-like carbon film formed on an inner wall surface, wherein the diamond-like carbon film has a thickness of 50 to 400 mm and a density of 1.2 to 1.59 g / cm ^3. Characteristic diamond-like carbon film coated plastic container. A gas barrier plastic container having a diamond-like carbon film formed on an inner wall surface, wherein the diamond-like carbon film has a thickness of 50 to 400 mm and a density of 1.2 to 1.48 g / cm ^3. Characteristic diamond-like carbon film coated plastic container.   The diamond-like carbon film-coated plastic container according to claim 12 or 13, wherein the diamond-like carbon film has a hydrogen content in the range of 16 to 52 hydrogen atom%. A gas barrier plastic container having a diamond-like carbon film formed on an inner wall surface, wherein the diamond-like carbon film has a thickness of 232 to 432 mm and a density of 1.39 to 1.46 g / cm ^3. Characteristic diamond-like carbon film coated plastic container. A gas barrier plastic container having a diamond-like carbon film formed on an inner wall surface, wherein the diamond-like carbon film at the bottom of the gas barrier plastic container has a thickness of 215 to 304 mm and a density of 1.48 to 1.59 g / A diamond-like carbon film coated plastic container characterized by being in the range of cm ³ .   A diamond-like carbon film-coated plastic container manufactured by using the diamond-like carbon film-coated plastic container manufacturing apparatus according to claim 1, 2, 3, 4, 5, or 6.

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