JP2001031045A - Dlc film, plastic container, and manufacturing apparatus for carbon film-coated plastic container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plastic container suitable for a container for drinks sensitive to oxygen or for sparkling drinks and a manufacturing apparatus capable of manufacturing such a plastic container. SOLUTION: A DLC film whose thickness is 50 to 400 Å is formed on an inner wall face of a plastic container. The DLC film can be formed by using a manufacturing apparatus comprising an outer electrode arranged outside the plastic container 5, an inner electrode 11 arranged inside the plastic container 5, a pipe passage 12 for feeding material gas in a carbon source into the inside of the decompressed plastic container 5, and a high-frequency oscillator 9 for forming a rigid carbon film on the inner wall face of the plastic container 5 by allowing a plasma to be generated by applying a voltage to a space between the outer electrode and the inner electrode 11 after feeding the material gas. The outer electrode comprises a bottom-part electrode 4 to be arranged along a bottom of the plastic container 5 and a body-part electrode 3 to be arranged along a body of the plastic container 5, and an upper end of the bottom-part electrode 4 is positioned lower than a central position between an upper and a lower ends of the plastic container 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing a carbon film-coated plastic container which can be used as a container for oxygen-sensitive beer, low-malt beer, wine, high juice drinks and the like.

[0002]

2. Description of the Related Art In general, plastic containers are widely used as filling containers in various fields such as foods and pharmaceuticals because of their ease of molding, light weight and low cost. I have.

However, as is well known, plastic has a property of transmitting low molecular gas such as oxygen and carbon dioxide and a property of sorbing low molecular organic compounds. For this reason, the plastic container is subject to various restrictions on its use object and use form as compared with a glass container or the like.

For example, when a plastic container is used as a filling container for carbonated beverages such as beer and wine, etc.,
Oxygen permeates the plastic to oxidize the beverage over time, or carbon dioxide gas in the carbonated beverage permeates the plastic and is released to the outside of the container, so that the carbonated beverage is lost. Therefore, the plastic container is not suitable as a container for filling a beverage that does not like oxidation or a carbonated beverage.

When a plastic container is used as a container for filling 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 added to the plastic. Because of the sorption, the composition of the aroma components of the beverage is unbalanced, and the quality of the beverage deteriorates. Therefore, the plastic container is not suitable as a container for filling a beverage having an aroma component.

[0006] On the other hand, in recent years, especially, recycling of resources has been called out, and the collection of used containers has become a problem. When a plastic container is used as a returnable container, unlike a glass container, if the plastic container is left in the environment at the time of collection, various low-molecular organic compounds such as mold odor are sorbed on the plastic during that time. Would. For this reason, in the related art, examples of using a plastic container as a returnable container have been limited.

However, as described above, the plastic container has characteristics such as ease of molding, light weight, and low cost, so that the plastic container is used as a filling container for carbonated beverages and beverages having aroma components. It would be very convenient if it could be used as a container for filling substances requiring purity and also as a returnable container.

[0008]

Japanese Patent Application Laid-Open No. 8-53117 discloses a container which can meet such a demand.
n) A container with a membrane and a device for producing such a container are disclosed. The DLC film is a hard carbon film also 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 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 production apparatus capable of producing a carbon film-coated plastic container suitable as a container for oxygen-sensitive beverages and sparkling beverages.

[0010]

According to the first aspect of the present invention, an outer electrode disposed outside a plastic container (5) and an inner electrode (11) disposed inside a plastic container (5) are provided. Vacuum means for reducing the pressure in the plastic container (5), gas supply means (12 or the like) for supplying a carbon source gas to the inside of the plastic container (5) reduced in pressure by the vacuum means, and gas supply means (12). After the supply of the raw material gas by the above method, a voltage is applied between the outer electrode and the inner electrode (11) to generate plasma, thereby forming a hard carbon film on the inner wall surface of the plastic container (5) (8). , 9), wherein the outer electrode comprises a first electrode (4) arranged along the bottom of the plastic container (5);
A second electrode (3) arranged along the body of the plastic container, and the upper end of the first electrode (4) is positioned lower than the center of the upper and lower ends of the plastic container (5). It is characterized by being able to.

In the present invention, the outer electrode is connected to the first electrode (4).
And the second electrode (3), so that appropriate power can be supplied to each part.

According to a second aspect of the present invention, in the apparatus for manufacturing a carbon film-coated plastic container according to the first aspect, the power supply device (8, 9) includes a second electrode connected to the first electrode (4).
A higher power is applied than the electrode (3).

According to the present invention, since a higher power is applied to the first electrode (4) than to the second electrode (3), the container (5)
A hard carbon film having an appropriate thickness can be formed over the entire surface.

According to a third aspect of the present invention, in the apparatus for manufacturing a carbon film-coated plastic container according to the first or second aspect, the outer electrode is provided above the second electrode (3). And 5) a third electrode (2) arranged along the shoulder.

According to a fourth aspect of the present invention, there is provided an outer electrode disposed outside a plastic container (5), an inner electrode (11) disposed inside the plastic container (5), and a plastic container (5). Vacuum means for depressurizing the inside, gas supply means (12 or the like) for supplying a raw material gas of a carbon source to the inside of the plastic container (5) decompressed by the vacuum means, and source gas by the gas supply means (12 or the like) After the supply, a power supply device (8, 9) for forming a hard carbon film on the inner wall surface of the plastic container (5) by applying a voltage between the outer electrode and the inner electrode (11) to generate plasma. A first electrode (4) arranged along the bottom of the plastic container (5), and a second electrode (3) arranged along the body of the plastic container (5). ,
Third placed along the shoulder of the plastic container (5)
(2).

According to the present invention, the outer electrode is connected to the first electrode (4).
, The second electrode (3), and the third electrode (2), so that appropriate power can be supplied to each part.

According to a fifth aspect of the present invention, in the apparatus for manufacturing a carbon film-coated plastic container according to the fourth aspect, the power supply device (8, 9) includes a second electrode connected to the first electrode (4).
A higher power is applied than the electrode (3).

In the present invention, since a higher power is applied to the first electrode (4) than to the second electrode (3), the container (5)
A hard carbon film having an appropriate thickness can be formed over the entire surface.

According to a sixth aspect of the present invention, there is provided a DLC film formed on a surface of a plastic, wherein the DLC film has a thickness of 50 to 40.
It is characterized by being in the range of 0 °.

In the present invention, the thickness of the DLC film is 50 to 4
Since it is within the range of 00 °, it is possible to prevent a decrease in transparency due to coloring of the DLC film while effectively reducing the oxygen permeability. In addition, the generation of cracks in the DLC film due to the compressive stress can be prevented, so that the oxygen barrier property can be prevented from lowering, and the deposition time required for forming the DLC film is shortened, so that productivity is improved.

According to a seventh aspect of the present invention, in the DLC film according to the sixth aspect, the hydrogen content is 16 to 52 hydrogen atom%.
In the range.

The invention according to claim 8 is a DLC film formed on a surface of a plastic, wherein the DLC film has a hydrogen content of 16 to 16.
It is characterized by being in the range of 52 atomic% of hydrogen.

According to a ninth aspect of the present invention, in the DLC film according to any one of the sixth to eighth aspects, the density of the DLC film is in a range of 1.2 to 2.3 g / cm ^3. Features.

According to a tenth aspect of the present invention, there is provided a plastic container in which a DLC film is formed on an inner surface of a plastic, wherein the thickness of the DLC film is in a range of 50 to 400 °.

In the present invention, the thickness of the DLC film is 50 to 4
Since it is within the range of 00 °, it is possible to prevent a decrease in transparency due to coloring of the DLC film while effectively reducing the oxygen permeability. In addition, the generation of cracks in the DLC film due to the compressive stress can be prevented, so that the oxygen barrier property can be prevented from lowering, and the deposition time required for forming the DLC film is shortened, so that productivity is improved.

According to an eleventh aspect of the present invention, in the plastic container according to the tenth aspect, the hydrogen content of the DLC film is in a range of 16 to 52 hydrogen atom%.

According to a twelfth aspect of the present invention, there is provided a plastic container in which a DLC film is formed on an inner surface of a plastic, wherein the hydrogen content of the DLC film is in a range of 16 to 52 hydrogen atom%.

The invention according to claim 13 is the invention according to claim 10
13. The plastic container according to any one of the above items 12, wherein the density of the DLC film is in a range of 1.2 to 2.3 g / cm ³ .

Incidentally, 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.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an apparatus for producing a DLC film and a carbon film-coated plastic container according to the present invention will be described with reference to FIGS.

FIG. 1 is a diagram showing an electrode configuration and the like of the present apparatus. As shown in FIG. 1, the present apparatus includes a base 1, a shoulder electrode 2 and a body electrode 3 attached to the base 1, and a bottom electrode 4 detachably attached to the body electrode 3. Prepare. As shown in FIG. 1, each of the shoulder electrode 2, the body electrode 3, and the bottom electrode 4 has an inner wall surface having a shape conforming to the outer shape of the plastic container 5. The body electrode 3 is arranged on the body of the plastic container 5, and the bottom electrode 4 is arranged along the bottom of the plastic container 5. The shoulder electrode 2, the body electrode 3 and the bottom electrode 4 constitute the outer electrodes of the device.

When the bottom electrode 4 is mounted on the body electrode 3, the base 1, the shoulder electrode 2, the body electrode 3 and the bottom electrode 4 are airtightly attached to each other. It functions as a vacuum chamber including a storage section 10 for storing the container 5.

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

The housing 10 is provided with an inner electrode 11, and the inner electrode 11 is inserted into the plastic container 5 housed in the housing 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 a lower end thereof is formed with one blowout hole (not shown) for communicating the inside and the outside of the inner electrode 11. In addition, instead of providing a blowing hole at the lower end, a plurality of blowing holes (not shown) penetrating the inside and outside of the inner electrode 11 in a radial direction.
May be formed. The inner electrode 11 is connected to a conduit 12 communicating with the inside of the inner electrode 11, and the raw material gas sent into the inner electrode 11 through the conduit 12 is supplied to the plastic container 5 through the blowing hole. It is configured to be released into The conduit 12 is made of metal and has conductivity, and as shown in FIG.
1 is connected to the ground potential. Also, the inner electrode 11
Are supported by a conduit 12.

As shown in FIG. 1, an output terminal 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 between the ground electrode and the high-frequency oscillator 9, whereby a high-frequency voltage is applied between the inner electrode 11 and the bottom electrode 4.

Next, the plastic container 5
A procedure for forming a DLC (Diamond Like Carbon) film on the inner wall surface of the above 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 stored in the storage section 10 by raising the bottom electrode 4. At this time, the inner electrode 1 provided in the housing 10
1 is inserted into the inside of the plastic container 5 through the opening (opening at the upper end) of the plastic container 5.

When the bottom electrode 4 is raised to a predetermined position and the storage section 10 is sealed, the outer periphery of the plastic container 5 comes into contact with the shoulder electrode 2, the body electrode 3 and the inner surface of the bottom electrode 4. . Next, the air in the storage unit 10 is exhausted through the exhaust port 1A 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, the raw material gas (for example, a carbon source gas such as an aliphatic hydrocarbon or an aromatic hydrocarbon) sent through the pipe 12 is used. Is introduced into the plastic container 5 from the outlet 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. Thereby, 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 is formed on the inner wall surface of the outer electrode which is insulated by the plasma generated between the outer electrode and the inner electrode 11. The electrons accumulate, causing a predetermined potential drop.

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

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. In addition, 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 body electrode 3 and the shoulder electrode 2, and the body electrode 3 and the shoulder electrode 2 are electrically insulated from each other. Therefore, the high-frequency power applied to the body 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 the body electrode 3 and the shoulder electrode 2 are capacitively coupled through the respective gaps, the body electrode 3 and the shoulder electrode 3 are coupled. 2, a certain amount of high-frequency power is applied.

Generally, 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 is insufficiently stretched in manufacturing, the gas barrier property of the plastic itself is low at the bottom. Therefore, 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 inventor of the present invention, a plastic bottle was used as a plastic container, and the same high-frequency power was applied to the entire outer electrodes corresponding to the shoulder electrode 2, the body electrode 3 and the bottom electrode 4. In the case, the DLC film was thickly coated from the mouth of the plastic bottle to the shoulder, the body was thinner, and the thickness of the bottom was extremely thin. In this case, as described above, the gas barrier property of the plastic itself is low at the bottom, so that the gas barrier property of the entire bottle is greatly reduced. If a sufficient thickness is to be obtained, the time required for coating is required to be 20 to 30 seconds, which increases the manufacturing cost. Further, in the portion where the DLC film is thickly formed, the DLC film is liable to peel off, and if the coating time is prolonged 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 a uniform high-frequency power was applied to the entire outer electrode, the gas barrier property could 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-described embodiment, a high-frequency power larger than that of the body or shoulder can be applied to the bottom of the plastic container. It is possible to form a film, and it is also 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 properties of the entire container can be effectively improved. In the above embodiment, the applied power can be increased to 1200 to 1400 W, and therefore, the manufacturing cost can be reduced by shortening the coating time.

Further, in the above embodiment, since a sufficient high-frequency power can be applied to the bottom portion while suppressing the high-frequency power at the mouth portion and the shoulder portion of the container, the plastic container can be densely formed while suppressing deformation. A DLC film having good adhesion to the inner wall surface of the plastic container 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 each electrode is made of a resistive or capacitive element or the like. May be connected to each other. In short, it is sufficient that high-frequency power of a required size can be applied to each part of the container. For example, each of the shoulder electrode 2, the body electrode 3, and the bottom electrode 4 is separately provided. A plurality of high-frequency oscillators may be prepared so as to apply high-frequency power to the power supply, or the output of a single high-frequency oscillator may be connected to each electrode via a plurality of matching devices.

In the above embodiment, the case where the outer electrode is divided into three parts is exemplified. However, the outer electrode may be divided into two parts, or may be divided into four or more parts.

Further, in the above embodiment, the container having a shape in which the DLC film is hardly formed on the bottom is described. However, by adjusting the distribution of the applied high-frequency power according to the shape of the container, the entire container can be adjusted. A good DLC 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 (the content is filled once without being collected). For disposable use).

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

FIG. 2 shows the conditions of plasma CVD and PET.
FIG. 3 shows a dimensional shape of the bottle and the like, and FIG. 3 shows a method of evaluating the bottle having the DLC film formed on the inner wall surface. FIG. 4 shows the film formation conditions and evaluation results when toluene was used as the source gas, and FIG. 5 shows the film formation conditions and evaluation results when acetylene was used as the source gas.

In the table of “dimensions of plastic bottle” in FIG. 2B, “bottom / shoulder + body + bottom” means the ratio of the portion where the bottom electrode 4 faces to the height of the entire bottle, That is, a 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 to the upper end of the bottle)” is shown as a percentage.

In the table of “Dimensions of plastic bottle”,
"700ml PET bottle" and "500ml PP
(Polypropylene) bottle ”column contains 500 bottles for each type of bottle prepared as an experimental object.
The dimensions and the location of the bottom electrode are shown similar to a ml PET bottle. 4 and 5 show 500 ml PE
Only the film formation conditions and evaluation results for the T bottle are shown.

In “(7) Discharge method of external electrode” in FIG. 2A, “whole” means that the shoulder electrode 2, the body electrode 3 and the bottom electrode 4 are electrically short-circuited and these electrodes are connected. The case where the same high frequency power is applied at the same time is shown. "Body
“Bottom” means that the body electrode 3 and the bottom electrode 4 are electrically short-circuited, and the shoulder electrode 2 is insulated from the body electrode 3, and the same high-frequency is applied to the body electrode 3 and the bottom electrode 4 simultaneously. This shows a case where power is applied. "Bottom"
This 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 column of “discharge method” shown in FIGS.

In the evaluation of “(1) Evaluation by appearance” and “(2) Deformation of container” in FIG. 3, “」 ”indicates the best condition, and“ X ”indicates the worst condition. .
These evaluation results are described in predetermined columns of the tables shown in FIGS. 4 and 5, respectively.

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

Regarding the plasma conditions of Experiment Nos. 1 to 6,
It is described below. Acetylene was used as a source gas, and a method of applying high-frequency power to the bottom electrode 4 was used as a discharging 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. 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. Experiment number 1 is D
This is a PET bottle on which no LC film is formed.

FIG. 6 shows the plasma times of Experiment Nos. 1 to 6, D
The thickness of the LC film and the oxygen permeability are shown. FIG.
(A) and FIG.7 (b) have shown the shape of the PET bottle.

The height A 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 the other parts shown in FIG.
B = 68.5 mm, C = 35.4 mm, D = 88 mm,
E = 2mm, F = 22.43mm, G = 24.94m
m, H = 33 mm, J = 67.7 mm, K = 26.16
mm, L = 66.5 mm, M = 21.4 mm, N = 46
mm. The wall thickness of PET bottle 100 is 0.4
mm.

In FIG. 6, the numerical values in the column of film thickness indicate PET values.
DLC at shoulder, body, and bottom of bottle 100
The thickness of the film was measured, and the range between the minimum value and the maximum value was shown as the range of the thickness of the DLC film.

As shown in FIG. 6, in the PET bottle of Experiment No. 1 in which the DLC film was not formed, the oxygen permeability was 0.033 ml / day / container, whereas the oxygen permeability was 0.033 ml / day / container.
In the PET bottle of Experiment No. 2 in which the DLC film of ~ 75 ° was formed, the oxygen permeability per container (PET bottle) was 0.008 ml / day. Thus, 50-75Å
Oxygen permeability can be reduced to about 1/4 by forming a DLC film as thin as possible. In addition, as shown in FIG.
In the PET bottle of No. 6, the oxygen permeability is further reduced. By forming the DLC film having a relatively small thickness of about 50 to 400 °, the oxygen permeability can be effectively reduced.

When a thin DLC film is formed on the inner wall surface of a PET bottle as in Experiment Nos. 2 to 6, there are the following advantages. First, the DLC film is colored slightly yellow, and as the film thickness increases, the color gradually becomes black,
The container becomes less transparent. However, by setting the thickness of the DLC film to be thin, the transparency of the container can be improved. Also, when the thickness of the DLC film increases, the DL
A large compressive stress acts on the C film to cause cracks in the DLC film, resulting in a problem that the oxygen barrier property is deteriorated. However, such a problem can be avoided by forming the DLC film thin as described above. Further, when the film thickness is set to be thin, the vapor deposition time required for forming the film thickness is shortened, so that the productivity is improved.

The oxygen permeability shown in FIG.
The measurement was performed at 22 ° C. and 60% RH using Oxtran manufactured by trol. DLC film thickness is Tenchol company alpha
The measurement was carried out using a stylus type step meter of -step 500.

Example 3 Hereinafter, with reference to FIG. 8, the density of a DLC film formed on the inner wall surface of a 500 ml PET bottle by using the above apparatus will be described.

The plasma conditions in the PET bottles of Experiment Nos. 7 to 10 will be described below. Acetylene was used as a source gas, and a method of applying high-frequency power to the bottom electrode 4 was used as a discharging 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 measurement results of the density. In the column of "discharge method" in FIG. 8, "whole" means that the shoulder electrode 2, the body electrode 3 and the bottom electrode 4 were electrically short-circuited and the same high-frequency power was applied to these electrodes simultaneously. (Experiment numbers 7 and 8). "Bottom" indicates that 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 (Experiment Nos. 9 and 10).

The column of “high-frequency applied voltage” indicates the high-frequency power applied in each experiment number. In FIG. 8, the thickness of the DLC film, the volume of the DLC film, and the DLC for the shoulder, trunk, and bottom of the PET bottle of each experiment number
The weight of the membrane and the density of the DLC membrane are shown, and the part of the PET bottle corresponds to the indication of “shoulder”, “body”, and “bottom” in the column of “part of container”.

The oxygen permeability shown in FIG.
The measurement was performed at 22 ° C. and 60% RH using Oxtran manufactured by trol. DLC film thickness is Tenchol company alpha
The measurement was carried out with a stylus type step meter of -step 500. The surface area of the PET bottle was calculated by CAD from the drawing of the PET bottle.

In the measurement of the weight of the DLC film, PET was used.
The bottle 100 was divided into three parts, a shoulder, a body and a bottom. Next, these parts are immersed in a 4% aqueous solution of NaOH in a beaker and reacted at room temperature for about 10 to 12 hours.
The film was peeled off. This solution was filtered through a polytetrafluoroethylene-made Millipore filter (pore size: 0.5 μm), dried at 105 ° C., and weighed together with the Millipore filter. By subtracting the weight of the Millipore filter before use for filtration from this weight, the weight of the peeled DLC film was obtained. Further, since the NaOH solution has a residue as an impurity, the blank value of the NaOH solution was also obtained, and the weight of the DLC film was corrected.

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

[0075]

## EQU1 ## Density = weight / (surface area × thickness) Equation (1)

As shown in FIG. 8, there was no apparent difference in the density of the DLC film depending on the discharge method, the magnitude of the high-frequency applied power, or the position of the PET bottle.
The range of the density of the C film was 1.2 to 2.3 g / cm ³ .

Example 4 Hereinafter, with reference to FIG. 9, the hydrogen content of a DLC film formed on the inner wall surface of a 500 ml PET bottle using the above apparatus will be described.

In Experiment Nos. 11 and 12, a glass substrate (length: 23 mm, width: 19 mm, thickness: 0.5 mm) was placed on each of the predetermined regions of the shoulder, the trunk, and the bottom.
Was attached. 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, reference symbol “P” denotes an upper region provided on a shoulder portion, reference symbol “Q” denotes a middle region provided on a body portion, and reference symbol “R” denotes a lower region provided on a bottom portion. , Respectively. The lower end of the upper region P is 125 mm above the bottom of the PET bottle, and the upper end of the upper region P is 144 mm above the bottom of the PET bottle. The lower end of the middle region Q is 65 mm above the bottom of the PET bottle, and the upper end of the middle region Q is 84 mm above the bottom of the PET bottle. The lower end of the lower region R is located 1 upward from the bottom of the PET bottle.
1 mm, the upper end of the lower region R is located 30 mm above the bottom of the PET bottle.

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

FIG. 9 shows 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. The indications of “upper”, “middle”, and “lower” described in “region” 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 densities of the DLC film are 1.2, 1.8, and 2.3, respectively. The hydrogen content was measured for each site.

For measuring the hydrogen content, Shimadzu IBA-990 was used.
The hydrogen concentration% (ratio of the number of hydrogen atoms) in the DLC film was measured by using 0 EREA (elastic recoil detection analysis).

As shown in FIG. 9, the hydrogen content increases when the high frequency applied power is large (Experiment No. 12). Also,
There is a tendency for the hydrogen content to decrease slightly with increasing density.

In the above embodiment, the DLC film is formed by generating plasma by applying high frequency power, 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 be applied to a plastic container made of a material other than PET or PP.
Moreover, it can also be used for uses other than containers.

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

[0088]

According to the first aspect of the present 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 present 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. Can be.

According to the sixth aspect of the present invention, since the thickness of the DLC film is in the range of 50 to 400 °, the transparency caused by the coloring of the DLC film is reduced while effectively reducing the oxygen permeability. Drop can be prevented. In addition, D due to compressive stress
Since the occurrence of cracks in the LC film is prevented, a decrease in oxygen barrier properties can be prevented, and the deposition time required for forming the DLC film is shortened, so that productivity is improved.

According to the tenth aspect, the DLC
Since the thickness of the film is in the range of 50 to 400 °, it is possible to effectively reduce the oxygen permeability and to prevent a decrease in transparency due to coloring of the DLC film. In addition, the generation of cracks in the DLC film due to the compressive stress can be prevented, so that the oxygen barrier property can be prevented from lowering, and the deposition time required for forming the DLC film is shortened, so that productivity is improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a manufacturing apparatus according to the present invention.

2A and 2B are diagrams illustrating conditions of plasma CVD, dimensions of a plastic bottle, and the like. FIG. 2A is a diagram illustrating conditions of plasma CVD, and FIG. 2B is a diagram illustrating dimensions of a plastic bottle.

FIG. 3 is a view showing a method for evaluating a 500 ml PET bottle on which a DLC film is formed.

FIG. 4 is a view showing evaluation results of a 500 ml PET bottle on which a DLC film is formed using toluene as a raw material gas.

FIG. 5 is a diagram showing evaluation results of a 500 ml PET bottle on which a DLC film is formed using acetylene as a source gas.

FIG. 6 is a view showing film formation conditions, film thickness, and oxygen permeability of DLC films in bottles of Experiment Nos. 1 to 6.

7A and 7B are diagrams showing the shape of a PET bottle, wherein FIG. 7A is a front view, and FIG. 7B is a bottom view as seen from the direction of line BB in FIG.

FIG. 8 is a view showing the conditions for forming a DLC film, the density, and the like in the bottles of Experiment Nos. 7 to 10.

FIG. 9: DL in bottles of experiment numbers 11 and 12
FIG. 4 is a view showing film forming conditions, hydrogen content, and the like of a C film.

[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 Pipeline 100 PET bottle

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[Procedure amendment]

[Submission Date] October 25, 1999 (1999.10.
25)

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[Document name to be amended] Drawing

[Correction target item name] Fig. 8

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[Procedure amendment]

[Submission date] December 28, 1999 (1999.12.
28)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

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[Claims]

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigeki Mori 4-5-15 Ueno, Iwatsuki City, Saitama Prefecture Within the Technology Division of Hokkai Seikan Co., Ltd. (72) Inventor Yuji 4-5-15 Ueno, Iwatsuki City, Saitama Prefecture (72) Inventor Tsuyoshi Kamo 1-2-27 Nishigotanda, Shinagawa-ku, Tokyo F-term (reference) 3M033 AA02 BA13 BA16 BA18 BB08 CA16 DA02 DA08 DB01 DD05 EA04 EA05 EA10 FA04 GA02

Claims (13)

[Claims] 1. An outer electrode disposed outside a plastic container, an inner electrode disposed inside the plastic container, a vacuum means for depressurizing the inside of the plastic container, and the plastic depressurized by the vacuum means. A gas supply unit that supplies a source gas of a carbon source to the inside of the container; and after the supply of the source gas by the gas supply unit, a voltage is applied between the outer electrode and the inner electrode to generate plasma. A power supply device for forming a hard carbon film on an inner wall surface of the plastic container, wherein the outer electrode is provided along a first electrode disposed along a bottom portion of the plastic container, and along a body portion of the plastic container. And an upper end of the first electrode is located below a central position of upper and lower ends of the plastic container. Carbon film coated plastic container manufacturing apparatus characterized by being kicked. 2. The apparatus according to claim 1, wherein the power supply device applies higher power to the first electrode than to the second electrode. 3. The method according to claim 1, wherein the outer electrode includes a third electrode provided above the second electrode and arranged along a shoulder of the plastic container. An apparatus for producing a carbon film-coated plastic container according to the above. 4. An outer electrode disposed outside a plastic container, an inner electrode disposed inside the plastic container, a vacuum means for reducing the pressure in the plastic container, and the plastic reduced in pressure by the vacuum means. A gas supply unit that supplies a source gas of a carbon source to the inside of the container; and after the supply of the source gas by the gas supply unit, a voltage is applied between the outer electrode and the inner electrode to generate plasma. A power supply device for forming a hard carbon film on an inner wall surface of the plastic container, wherein the outer electrode is provided along a first electrode disposed along a bottom portion of the plastic container, and along a body portion of the plastic container. And a third electrode disposed along a shoulder of the plastic container. Packaging plastic container manufacturing device. 5. The apparatus according to claim 4, wherein the power supply device applies a higher power to the first electrode than to the second electrode. 6. DLC formed on the surface of plastic
A film having a thickness in the range of 50 to 400 °
LC membrane. 7. The DLC film according to claim 6, wherein the hydrogen content of the DLC film is in a range of 16 to 52 atomic%. 8. DLC formed on the surface of plastic
A DLC film, wherein the hydrogen content is in the range of -atomic% hydrogen. 9. The DLC film having a density of 1.2 to 2.3 g.
DLC film according to any one of claims 6-8, characterized in that the range of / cm ^3. 10. A plastic container having a DLC film formed on an inner wall surface, wherein the thickness of the DLC film is in the range of 50 to 400 °. 11. The DLC film having a hydrogen content of 16 to 52.
The plastic container according to claim 10, wherein the content is in the range of atomic% of hydrogen. 12. A plastic container having a DLC film formed on an inner wall surface thereof, wherein the hydrogen content of the DLC film is in a range of 16 to 52 atomic% by hydrogen. 13. The DLC film having a density of 1.2 to 2.3.
g / cm ^3.
13. The plastic container according to any one of 12 above.