JP3665052B2 - Method for producing gas permeation preventive membrane coated plastic container - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a gas-permeable prevention film-coated plastic container.
[0002]
[Prior art]
Plastic containers, such as PET bottles, are coated with a carbon film such as DLC (Diamond Like Carbon) on the inner surface to prevent the permeation of oxygen from the outside and the penetration of carbon dioxide from the inside (for example, carbonated drinking water). Attempts have been made to produce a plastic container coated with a gas permeation prevention film.
[0003]
As a method of coating a carbon film on the inner surface of such a plastic container, methods using high-frequency plasma are disclosed in Japanese Patent Application Laid-Open No. 8-53116 and Japanese Patent No. 2788412 (Japanese Patent Application Laid-Open No. 8-53117). Japanese Patent Application Laid-Open No. 9-272567 discloses a method of coating a film with a carbon film using high-frequency plasma as an applied method. Japanese Patent No. 3072269 (Japanese Patent Laid-Open No. 10-226884) discloses a carbon film coating method corresponding to a specially shaped container, while Japanese Patent No. 3115252 (Japanese Patent Laid-Open No. 10-258825) includes a plurality of mass production techniques. A method for simultaneously coating a container is disclosed. References disclosing the technology for coating carbon films on plastic containers include “K. Takemoto, et al, Proceedings of ADC / FCT '99, p285”, “E. Shimamura et al, 10th years IAPRI World Conference 1997. , p251 ”.
[0004]
Incidentally, a carbon film coating apparatus having the following structure is used for coating a carbon film on a plastic container by high-frequency plasma CVD. That is, this apparatus is composed of a cylindrical main body and a cap portion attached to the upper end of the main body, and has an inner shape substantially in line with the outer shape of a plastic container, for example, a plastic bottle, and also serves as a vacuum container, A gas exhaust pipe communicated with the external electrode, an internal electrode serving also as a gas supply inserted into the external electrode through the exhaust pipe, a roughing exhaust pump communicated with the exhaust pipe, the exhaust pipe, A roughing exhaust valve interposed between the roughing exhaust pump, a film forming gas exhaust pump communicated with the exhaust pipe, and a component interposed between the exhaust pipe and the film forming gas exhaust pump. A film gas exhaust valve, a film forming gas supply source for supplying a film forming gas, for example, acetylene gas, to the internal electrode, and the gas supply source between the internal electrode and the source gas supply source. It includes a mass flow controller and the deposition gas supply valve which are sequentially interposed, and a high frequency power source connected to said external electrodes.
[0005]
The carbon film forming process by such a carbon film coating apparatus is shown in FIG. 4 for roughing exhaust valve, film forming gas exhaust valve, film forming gas supply valve opening / closing, mass flow flow rate, actual gas inflow amount and high frequency power supply This will be described with reference to an on / off timing chart.
[0006]
First, a plastic container, for example, a PET bottle is accommodated in the external electrode. By operating the roughing exhaust pump and opening the roughing exhaust valve, the gas in the PET bottle stored in the external electrode is exhausted through the exhaust pipe. After the roughing exhaust pump is operated, the inside of the PET bottle reaches a vacuum level lower than the film forming pressure, and then the roughing exhaust pump is stopped and the roughing exhaust valve is closed. Here, the “attainment vacuum degree” is determined by a carbon film coating apparatus equipped with the roughing exhaust pump.
[0007]
Next, after opening the film formation gas supply valve and controlling the flow rate of the mass flow controller, a film formation gas (for example, acetylene) is supplied from the film formation gas supply source to the internal electrode through the mass flow controller and the film formation gas supply valve, A film forming gas is introduced into the PET bottle from the internal electrode portion located in the PET bottle. At this time, since the pressure in the PET bottle rises, the film forming gas exhaust pump is operated, and the film forming exhaust valve is opened, thereby exhausting the gas in the PET bottle through the exhaust pipe to evacuate the inside of the PET bottle. Maintain film deposition pressure. At the same time, plasma is generated between the external electrode and the grounded internal electrode, that is, in the PET bottle, by turning on the high-frequency power source and supplying high-frequency power to the external electrode. The film forming gas (for example, acetylene) is dissociated or further ionized by the plasma to generate a film forming species for forming a carbon film, and this film forming species is deposited on the inner surface of the PET bottle. Form. After the carbon film is formed to a predetermined thickness, the supply of high-frequency power is stopped, the deposition gas supply valve is closed, the deposition gas exhaust pump is stopped, the deposition gas exhaust valve is closed, Then, rare gas, air, or the like is supplied into the external electrode (pet bottle), and the space is returned to atmospheric pressure. Thereafter, the PET bottle is removed from the external electrode.
[0008]
[Problems to be solved by the invention]
According to the above-described method, a carbon film (gas permeation prevention film) having a high barrier property (for example, 10 times or more of a PET bottle) is coated in order to sufficiently rough the vacuum to an ultimate vacuum (0.01 Torr or less). It becomes possible to manufacture plastic bottles.
[0009]
However, it takes a very long time from the start of evacuation to the start of film formation by sufficiently roughing up to the ultimate vacuum, resulting in a longer film formation time, and when applied to mass production machines, especially rotary machines, production It causes a decline in sex.
[0010]
Further, when the flow rate control of the film forming gas (for example, acetylene) is performed by the mass flow controller, it takes time for the actual gas inflow amount of acetylene supplied to the PET bottle to be stabilized as shown in FIG. This also increases the time from the start of exhaust to the start of film formation.
[0011]
An object of the present invention is to provide a method capable of mass-producing a gas permeation prevention film-coated plastic container in which a plastic film inner surface is coated with a gas permeation prevention film such as a carbon film having a high barrier property.
[0012]
[Means for Solving the Problems]
The method for producing a plastic container covered with a gas permeation prevention film according to the present invention includes a step of exhausting a gas in a plastic container as a processing object, and an orifice buffer from the upstream side into the plastic container while continuing the gas exhaust. Supplying a raw material gas through a pipe having an orifice member and a valve, and continuing the gas exhaust, generating plasma in the plastic container to dissociate the raw material gas to dispose the inner surface of the plastic container A method for producing a gas permeation preventive film-coated plastic container comprising a step of forming a gas permeation preventive film on
The raw material gas is supplied into the plastic container by using the high-pressure raw material gas generated mainly in the orifice buffer section between the orifice member and the valve by opening the valve, and the supply time is supplied to the plastic by the gas exhaust. The gas pressure in the container is set in a range of 6 Torr or less to a film forming pressure.
[0013]
In the method for manufacturing a gas-permeable anti-film-coated plastic container according to the present invention, the volume of the orifice buffer portion of the orifice member and the orifice back pressure are controlled, whereby the amount of high-pressure source gas generated in the orifice buffer portion of the orifice member is reduced. It is preferable to adjust.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0015]
FIG. 1 is a schematic cross-sectional view showing a gas permeation prevention film coating apparatus used in the production of a gas permeation prevention film coated plastic container according to the present invention.
[0016]
This gas permeation preventive membrane coating apparatus includes an external electrode 1 having an inner shape substantially in line with the outer shape of a plastic container, for example, a PET bottle, and also serving as a vacuum container. The external electrode 1 includes an upper external electrode 1a and a lower external electrode 1b, and has a structure that can be divided vertically. The spacer 2 made of a dielectric material is interposed at least between the mouth and shoulder of the container and the external electrode 1 when the plastic container is accommodated in the external electrode 1.
[0017]
The gas exhaust pipe 3 is mounted on the upper external electrode 1a of the external electrode 1 so as to communicate with the opening. A rod-shaped internal electrode 4 also serving as a gas supply is inserted into the external electrode 1 and the spacer 2 through the gas exhaust pipe 3. The internal electrode 4 is electrically insulated from the external electrode 1 and the gas exhaust pipe 2 and is grounded.
[0018]
The roughing exhaust pump 5 is connected to the gas exhaust pipe 3 through a pipe 6 and a branch pipe 7a. The roughing exhaust valve 8 is interposed in the branch pipe 7a. The film forming gas exhaust pump 9 is connected to the gas exhaust pipe 3 through the pipe 6 and the branch pipe 7b. The film forming gas exhaust valve 10 is interposed in the branch pipe 7b. The capacity type pressure gauge 11 is attached to the gas exhaust pipe 3.
[0019]
A film forming gas supply source, for example, an acetylene cylinder 12 is connected to the upper end of the internal electrode 4 through a pipe 13. The orifice back pressure adjusting regulator 14, the filter 15, the orifice member 16, and the film forming gas supply valve 17 are sequentially interposed in the pipe 13 from the acetylene cylinder 11 side (upstream side). The orifice member 16 includes a casing 18 having an opening to which the pipe 13 is connected vertically and an orifice 19 disposed in the casing 18. The space of the casing 18 on the downstream side of the orifice 19 functions as the orifice buffer unit 20. A high frequency power source (not shown) is connected to the upper external electrode 1 a of the external electrode 1.
[0020]
Next, using the gas permeation prevention film coating apparatus shown in FIG. 1, the roughing exhaust valve, the film forming gas exhaust valve, and the film forming gas supply valve shown in FIG. 2 are opened and closed, and the amount of gas flowing into the chamber (pet bottle). Production of a gas permeation preventive film-coated plastic container (gas permeation preventive film-coated PET bottle) by forming a carbon film will be described with reference to a timing chart of turning on and off the high-frequency power source.
[0021]
First, the lower external electrode 1b is lowered to open the bottom of the upper external electrode 1a, a plastic container (for example, plastic bottle B) is inserted from the bottom of the upper external electrode 1a, and the lower external electrode 1b is connected to the upper external electrode 1a. The plastic bottle B is accommodated in the external electrode 1 and the spacer 2 by being attached to the bottom portion.
[0022]
Next, by operating the roughing exhaust pump 5 and opening the roughing exhaust valve 7, the gas in the plastic bottle B stored in the external electrode 1 and the spacer 2 is supplied to the gas exhaust pipe 3, pipe 6 and branch pipe 7a. Exhaust through. When the roughing exhaust pump 45 is actuated, the gas pressure in the PET bottle B reaches a film forming pressure (for example, 0.1 to 5 Torr), for example, a film forming pressure from 6 Torr or less. As shown, the roughing exhaust pump 5 is stopped and the roughing exhaust valve 8 is closed. Immediately after the closing operation of the roughing exhaust valve 8, the film forming gas supply valve 17 provided in the pipe 13 is opened, and acetylene is supplied from the acetylene cylinder 12 to the internal electrode 4 through the pipe 13, and from the lower end thereof Supply into plastic bottle B. At this time, the orifice back pressure adjusting regulator 14 interposed in the pipe 13 is set to a constant back pressure in advance, and then the film forming gas supply valve 17 is opened, so that the pipe 13 on the downstream side of the regulator 14 is connected. Since acetylene mainly retained in the orifice buffer portion 20 of the inserted orifice member 16 is instantaneously discharged, a large amount of acetylene is supplied into the PET bottle B at a high pressure. The film forming gas supply valve 17 is opened at the same time as the film forming exhaust valve 10 is opened, and the gas in the PET bottle B is supplied to the gas exhaust pipe 3, the pipe 6 and the branch pipe by the film forming gas exhaust pump 9 which is actuated in advance. Exhaust through 7b.
[0023]
In the operation of the film forming gas exhaust pump 9 and the supply of the acetylene, when the gas in the plastic bottle B is sufficiently replaced, the high frequency power is turned on and the high frequency power is applied to the external electrode 1, Plasma is generated between the external electrode 1 and the grounded internal electrode 4, that is, in the plastic bottle B. The acetylene is dissociated or further ionized by the plasma to generate a film forming species for forming a carbon film, and this film forming species is deposited on the inner surface of the PET bottle B to form a carbon film. After the carbon film is formed to a predetermined thickness, the supply of high-frequency power is stopped, the film formation gas supply valve 17 is closed, the film formation gas exhaust pump 9 is stopped, and the film formation gas exhaust valve 10 is closed. At the same time, nitrogen, rare gas, air, or the like is supplied into the PET bottle B, and the space is returned to atmospheric pressure. Thereafter, the plastic bottle B is removed from the external electrode 1.
[0024]
In addition to acetylene, for example, alkanes such as methane, ethane, propane, butane, pentane, and hexane; alkenes such as ethylene, propylene, butene, pentene, and butadiene; benzene, toluene, xylene, and indene Aromatic hydrocarbons such as naphthalene and phenanthrene; cycloparaffins such as cyclopropane and cyclohexane; cycloolefins such as cyclopentene and cyclohexene; and oxygen-containing hydrocarbons such as methyl alcohol and ethyl alcohol.
[0025]
As described above, according to the embodiment of the present invention, when the gas pressure in the plastic container (for example, PET bottle B) reaches the range of the film formation pressure (for example, 0.1 to 5 Torr) from 6 Torr or less, the film is formed. By supplying a gas (for example, acetylene gas) into the plastic bottle B through the pipe 13, the film formation is started from the start of exhaust as compared with the conventional method in which the film forming gas is supplied when the ultimate vacuum shown in FIG. 4 is reached. Time to start can be shortened.
[0026]
In addition, when the film forming gas is supplied, the orifice back pressure adjusting regulator 14 provided in the pipe 13 is set to a constant back pressure in advance, and then the film forming gas supply valve 17 is opened, and the downstream side of the regulator 14 is opened. The acetylene mainly retained in the orifice buffer portion 20 of the orifice member 16 interposed in the pipe 13 is instantaneously discharged, and a large amount of acetylene is supplied into the plastic bottle B at a high pressure. The gas can be replaced.
[0027]
Further, when the acetylene mainly retained in the orifice buffer section 20 of the orifice member 16 is instantaneously discharged and a large amount of acetylene is supplied into the PET bottle B at a high pressure, as shown in FIG. The gas flow into the bottle is stabilized in a short time. Specifically, when the diameter of the orifice 18 of the orifice member 16 is set to 100 μm in order to set the acetylene flow rate to 60 sccm, the acetylene gas inflow amount is stabilized in an extremely short time of 0.5 seconds or less as shown in FIG. . In this way, the time from the start of exhaust to the start of film formation can also be shortened by stabilizing the gas inflow amount in a short time.
[0028]
Therefore, when applied to a mass production machine, particularly a rotary machine, the production efficiency of a gas permeation prevention film-coated plastic container (for example, a gas permeation prevention film-coated PET bottle) can be improved. Moreover, since the gas in the PET bottle B can be replaced with acetylene in a short time, a PET bottle coated with a carbon film (gas permeation prevention film) having a high barrier property (for example, 10 times or more that of a PET bottle) is manufactured. Is possible.
[0029]
In addition, since the orifice member is about one digit cheaper than the mass flow controller, it has an advantage that a low-cost apparatus can be realized.
[0030]
By controlling the volume of the orifice buffer portion of the orifice member and the orifice back pressure by the regulator for adjusting the orifice back pressure, an appropriate amount of high-pressure raw material gas is supplied from the orifice buffer portion of the orifice member into the plastic container (pet bottle). Thus, the time from the start of exhaust to the start of film formation can be further shortened, and a carbon film (gas permeation preventive film) having higher barrier properties can be coated on the inner surface of the PET bottle.
[0031]
(Example 1)
Using the gas permeation preventive film coating apparatus shown in FIG. 1 described above, the roughing exhaust valve, the film forming gas exhaust valve, the film forming gas supply valve shown in FIG. 2 are opened and closed, the amount of gas flowing into the chamber (pet bottle), and the high frequency power source. In the embodiment in which a carbon film is formed according to the on / off timing chart of the above and the gas permeation prevention film-coated PET bottle is manufactured, when the gas pressure in the PET bottle B reaches the film forming pressure, An orifice buffer of the orifice member 16 interposed in the pipe 13 on the downstream side of the regulator 14 by opening the film forming gas supply valve 17 after setting the mounted regulator 14 for adjusting the orifice back pressure to a predetermined back pressure in advance. The acetylene mainly retained in the unit 20 is instantaneously discharged and a large amount of acetylene is supplied into the PET bottle B at a high pressure. By applying wave power to the external electrode 1, plasma is generated between the external electrode 1 and the grounded internal electrode 4, that is, in the PET bottle B, and deposited on the inner surface of the PET bottle B to form a carbon film A gas permeation-preventing membrane-coated PET bottle was produced by forming
[0032]
The barrier properties of the obtained PET bottles coated with gas permeation preventive membranes were examined. As a result, the carbon film was formed according to the timing chart of rough exhausting exhaust valve, film forming gas exhaust valve, film forming gas supply valve opening / closing, mass flow flow rate and high frequency power source on / off shown in FIG. It was confirmed that it has a high oxygen barrier property comparable to conventional gas permeation prevention film-coated PET bottles.
[0033]
In addition, the method of the present invention was able to shorten the time from the start of evacuation to the start of film formation by 5 seconds compared to the conventional method.
[0034]
In the present invention, the supply start time of acetylene is set to the time when the gas pressure in the PET bottle reaches the film formation pressure (for example, 0.1 to 5 Torr) from 6 Torr or less, so that the inside of the PET bottle (deposition chamber) ) Or explosion in the acetylene gas supply system can be avoided.
[0035]
That is, the explosion range of acetylene is 2.5% to 82% at atmospheric pressure (760 Torr).
[0036]
First, the explosion when acetylene flows into the film formation chamber in the air exhaust will be considered. The explosion limit when acetylene is mixed in the air is 2.5%, and the acetylene partial pressure at this time is 19 Torr. Therefore, even if the air is at atmospheric pressure, if the partial pressure at the time of supply of acetylene is 19 Torr or less, no explosion occurs in the chamber.
[0037]
Next, let us consider the explosion when the atmosphere flows backward from the deposition chamber side to the acetylene supply line. The explosion limit when air is mixed in acetylene is 82% acetylene, and the partial pressure of air at this time is 8%. Therefore, when the acetylene supply line is set to 1 atm, if the pressure is 8% or less, that is, 61 Torr or less, the air does not explode even if the air flows backward.
[0038]
In the first and second embodiments of the present invention, when the acetylene supply amount is set to a flow rate at which the film formation pressure (for example, 0.1 to 5 Torr) is obtained in a steady state, the mass flow rate is obtained by the following equation.
[0039]
Q = (p · V) /0.76
Here, Q: Mass flow rate (sccm), for example, 130 sccm,
P: Film forming pressure (Torr), for example, 0.1 Torr,
V: Exhaust speed (L / min) determined by the exhaust pump and the exhaust line, for example, 1000 L / min.
[0040]
In this case, since the film forming pressure is lower than 19 Torr which is the explosion limit, no explosion occurs even when acetylene is flowed at this flow rate during atmospheric suction.
On the other hand, in consideration of the case where the atmosphere flows back to the acetylene supply line, the mass flow rate is started to flow after the atmospheric pressure becomes 61 Torr or less. Actually, by setting the safety factor to 10 and 6 Torr as the upper limit of safety, it is possible to avoid the occurrence of an explosion even when the atmosphere flows backward to the acetylene supply line.
[0041]
【The invention's effect】
As described above in detail, according to the present invention, there is provided a method capable of mass-producing a gas permeable film-coated plastic container having a gas barrier film such as a carbon film having a high barrier property on the inner surface of the plastic container. can do.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing a gas permeation prevention film coating apparatus used for manufacturing a gas permeation prevention film coated plastic container according to an embodiment of the present invention.
FIG. 2 shows the rough exhaust valve, film formation gas exhaust valve, film formation gas supply valve opening / closing, gas flow rate into the chamber, and high frequency power supply in the manufacture of the gas permeation prevention film-coated plastic container according to the embodiment of the present invention. ON / OFF timing diagram.
FIG. 3 is a characteristic diagram showing the relationship between time and flow rate when acetylene is supplied from an orifice member having an orifice diameter of 100 μm.
FIG. 4 is a timing diagram of opening / closing of a roughing exhaust valve, a film forming gas exhaust valve, a film forming gas supply valve, a mass flow rate, and on / off of a high-frequency power source in manufacturing a conventional gas permeation prevention film-coated plastic container.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... External electrode, 3 ... Gas exhaust pipe, 4 ... Internal electrode, 5 ... Roughing exhaust pump, 9 ... Film-forming gas exhaust pump, 12 ... Acetylene cylinder, 14 ... Regulator for orifice back pressure adjustment, 16 ... Orifice member, 17: Deposition gas supply valve, 20: Orifice buffer, B: PET bottle.

Claims (2)

The process of exhausting the gas in the plastic container, which is the object to be processed, and continuing the gas exhaust, the raw material gas is supplied from the upstream side into the plastic container through a pipe having an orifice member having an orifice buffer part and a valve. A gas permeation preventive film coating comprising a step of supplying, and a step of generating a plasma in the plastic container to dissociate the source gas to form a gas permeation preventive film on the inner surface of the plastic container while continuing the gas exhaust A method of manufacturing a plastic container,
The raw material gas is supplied into the plastic container by using the high-pressure raw material gas generated mainly in the orifice buffer section between the orifice member and the valve by opening the valve, and the supply time is supplied to the plastic by the gas exhaust. A method for producing a plastic container coated with a gas permeation-preventing film, wherein the gas pressure in the container is set in a range from 6 Torr or less to a film forming pressure. 2. The gas permeation preventive membrane according to claim 1, wherein the amount of high-pressure raw material gas generated in the orifice buffer portion of the orifice member is adjusted by controlling the volume of the orifice buffer portion of the orifice member and the orifice back pressure. A method for producing a coated plastic container.

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