KR20110067236A - Apparatus and method for preparing dlc coating on the inner surface of plastic container - Google Patents

Abstract

PURPOSE: An apparatus and a method for the DLC coating a plastic container are provided to prevent a low molecular organic compound from being absorbed to a plastic container. CONSTITUTION: An apparatus for the DLC coating a plastic container comprises a vacuum dielectric closing unit(110), a vacuum pumping unit(120), spiral RF antennas(130), an RF power supply source(140), a slot type bias electrode(150), a pulse power device(160), a conductive electrode(170), and a gas supply device(180). The vacuum dielectric closing unit has an inner wall and a dimension corresponding to the outline of a plastic container(1). The vacuum pumping unit makes the inside the vacuum dielectric closing unit into a vacuum pressure state. The spiral RF antennas are arranged around the vacuum dielectric closing unit. The RF power supply unit is connected to the RF antennas through a matching network(141). The slot type bias electrode is installed along the circumference of RF currents induced by the RF antennas. The pulse power device applies repetitive voltage pulses to the bias electrode.

Description

Apparatus and method for preparing DLC coating on the inner surface of plastic container}

The present invention relates to an apparatus for low temperature plasma processing such as deposition, etching, and cleaning, and more particularly, to a barrier DLC (Diamond-Like-Carbon; diamond-like) on an inner wall of a plastic container by ICP-PI3D. Carbon), i.e., an apparatus and method for forming a coating layer of hydrogenated amorphous carbon (? -C: H), wherein ICP represents Iductively Coupled Plasma, and PI3D represents plasma immersion ion implantation and Plasma Immersion Ion Implantation and Deposition.

As is well known, plastics are materials which have a small weight compared to other materials such as glass, are easy to mold, unbreakable and inexpensive. For this reason, plastic containers are widely used as a packaging means in the food industry and the medical field.

However, plastics are known to adsorb low-molecular organic compounds, reducing the purity of the contents, accumulating odors, and permeability to oxygen and carbon dioxide. And the use of materials in containers for fragrance beverages such as juices. In particular, since it is difficult to remove the remaining odor, the plastic container cannot be used as a recoverable container. In addition, when distributing alcoholic beverages such as beer or carbonated beverages in a plastic container such as PET, there is a problem that the gaseous components including carbon dioxide inside the plastic container are gradually discharged to the outside of the container. This happens. Therefore, in the case of liquor, there is a problem in that it is expensive to use a plastic container and mainly use aluminum or a bottle.

To address these drawbacks, a hard carbon coating layer formed using Plasma Enhanced Chemical Vapor Deposition (PECVD) technology has been applied as a barrier layer on the surface of plastic containers. One example is disclosed in Japanese Patent Application Laid-Open No. 02-70059, wherein the plastic container is disposed in a chamber between two coaxial electrodes, a grounded inner electrode and an RF-powered outer electrode, and a capacitively coupled hydrocarbon plasma is When produced between the electrodes, a DLC film is formed on the inner and outer walls of the vessel. Effective ion implantation necessary to produce a hard carbon film is achieved by creating a negative self bias at the container surface. Although good quality test tools such as beakers can be fabricated, the apparatus and method described above have limited productivity due to the low plasma density and the relatively large size of the vacuum chamber compared to the vessel itself. Also, the DLC coating layer deposited on the outer wall of the container is inevitably damaged during the process of using the container.

The same drawbacks occur in an apparatus and method for forming a barrier DLC coating layer on the outer wall surface of a plastic container disclosed in US Pat. No. 6,854,309 to Shimada. The container in which the DLC membrane can be formed is also limited to a wide inlet plastic container having a small difference in diameter of the opening of the container and the body part. In this patent, capacitively coupled plasma (CCP) CVD is used to form the DLC coating layer.

Apparatus and methods for mass production of recoverable plastic containers having a barrier DLC coating on the inner wall are disclosed in US Pat. No. 6,294,226B1 to Shimamura and US Pat. No. 6,589,619B1 to Nagashima. An example of a device according to the invention disclosed in US Pat. No. 6,805,931B2 is shown in FIG. 2 for reference only. Here, the DLC coating layer is formed using CCP-CVD. In the case of applying the CCP-CVD technique, the distance between the outer electrode and the inner electrode should be the same along the vessel, in order to provide uniform thickness and similar properties of the coating layer throughout the vessel wall, especially if the vessel has a small mouth. It is difficult to ensure. In order to improve the uniformity of the coating layer along the vessel and to overcome the problem, the invention discloses dividing the external electrode into two insulated sections, each section being powered from a separate RF power source. . However, this complicates the device and increases the cost.

All conventional techniques as described above use PECVD techniques, where a capacitively coupled plasma (CCP) is used to decompose and ionize hydrocarbon precursor molecules, and the negative RF magnetic bias obtained by the vessel surface is active on the resulting DLC film. Provide ion implantation. The latter condition is essential for the deposition of hard carbon films with significant portions of C-C sp3 bonds.

While a single RF power supply can be used to provide relatively simple advantages when no charge builds up on the dielectric substrate, CCP-CVD has the following unique drawbacks:

Low plasma density of 10 ⁹ cm ^-3 , thus low DLC deposition rate;

Wide energy distributions of accelerated impact ions in the RF sheath; This causes a decrease in the hardness of the DLC membrane;

High pressure is required to increase the plasma density, which results in an RF sheath collision, thus extending the energy distribution of the impact ions and consequently softening the DLC coating layer;

The value of the RF self-bias depends on the RF power, pressure and gas type, which makes it difficult to optimize the process parameters;

The plasma density depends on the distance between the two electrodes where the discharge occurs locally, and in particular the container (bottom, sidewalls, inlet) in the DLC coating even where the dimensions of the internal electrodes are limited by the inner diameter of the container inlet. ), It is difficult to provide consistent properties and good adhesion.

Plasma non-uniformity causes local overheating of the plastic container over the glass transition temperature, which leads to container deformation.

A CCP-CVD method of DLC coating on the inner wall of a plastic container is disclosed in US Pat. No. 7,166,366B1 to Mori, where the DLC film thickness uniformity is such that the external electrodes forming the vacuum chamber are insulated from each other and capacitively coupled. It is improved by separating into three sections with and applying RF power to only one, ie bottom section of the electrode. Although this invention provides the good properties of a DLC coating, it does not solve the problems listed above inherent in CCP PVD.

In order to ensure the low price of DLC coated plastic containers, a complete low temperature RF plasma coating process is carried out in the manufacturing line, where the containers are continuously connected to a number of coating devices operating in a closed loop production process. Loaded / unloaded by In this case, it is desirable to apply power to several RF plasma devices from the same RF power supply to reduce hardware complexity and cost. 9 shows an equivalent electrical circuit for the case where some CCP-CVD devices are powered in parallel from a signal RF power source. The RF power supply is connected to the power electrode of each CCP device via a matching network MB. Each CCP is represented by the capacitance between the power supply and ground electrodes when there is no plasma, and by the sheath capacitance Csh when the plasma is ignited. In continuous processing, some of the devices are placed in a vacuum pumping or venting step where no plasma is present, while others are in the presence of a plasma in the DLC deposition step. In order to ensure even RF power distribution among all devices, the repeatable properties of the DLC coating are:

C _el >> C _sh (1)

Must be satisfied.

However, it is apparent to one of ordinary skill in the art that sheath capacitance is always superior in such devices. The value of Csh can be estimated using a semi-analytic model of dynamic sheath.

In the case of internal ion emitters, i.e. when the bias electrode surrounds the plasma (rs <rt), a steady state child sheath to target radius ratio can be obtained:

(2)

(2)

및

은 플라즈마 밀도 n₀에 대응하는 Debye 길이이다. here,

And

Is the Debye length corresponding to the plasma density n ₀ .

And for Child sheath capacitance:

(3)

(3)

Example 1:

ni = 5 × 10 ¹⁰ cm ^-3

Te = 3 eV

V0 = 1 kV

rt = 3 cm

l = 15 cm

Then Csh = 6000pF.

Thereby, when a CCP plasma is used in a device for DLC coating, a large difference between device impedance in the presence or absence of a plasma prevents the use of a single RF power supply to power some devices. do.

There is also a need to increase the throughput of DLC coatings on the inner walls of plastic containers by RF plasma treatment. This can be achieved by reducing the film deposition time when high plasma density is provided.

There is also a need to provide a DLC coating layer of uniform properties over the entire container wall. This can be realized if the method used is less sensitive to the shape of the device electrodes.

It is also necessary to ensure the good and repeatable properties of the DLC coating layer on the plastic container. This can be achieved if independent control of the main process parameters is useful.

There is also a need to lower the cost and improve reliability of devices for mass production of DLC coated plastic containers. This can be achieved by reducing the number of expensive and complex units such as RF power supplies.

It is an object of the present invention to overcome the problems of conventional methods and apparatus for barrier DLC coating layers on the inner wall of plastic containers.

Therefore, the present invention is invented to solve the above problems, to form a DLC coating layer of excellent quality that can suppress the absorption of low-molecular organic compounds in the container while having excellent oxygen barrier properties on the inner wall of the plastic container. It is a primary object to provide a device and method that can.

In particular, it is a main object to provide an apparatus and method for producing low-volume, recoverable plastic containers having a superior characteristic DLC coating on the inner wall by using devices operating in a closed loop production process.

In order to achieve the above object, the present invention is a device for forming a DLC coating layer on the inner wall of the plastic container, which has a detachable structure to accommodate the plastic container to be treated, and partly corresponding to the outline of the plastic container. A vacuum dielectric seal having an inner wall shape and dimensions; A vacuum pumping means connected to another part of the vacuum dielectric sealing part to make the inside of the vacuum dielectric sealing part into a vacuum pressure state; A spiral RF antenna disposed around the vacuum dielectric seal; An RF power supply source connected to and applying power to the antenna through a matching network to generate an RF current at the RF antenna; Preventing short circuits along the circumference for RF currents induced by the RF antenna and disposed around the perimeter of the plastic container within the vacuum dielectric enclosure with an outline and dimensions corresponding to the perimeter and dimensions of the plastic container. A detachable slotted bias electrode attached to the battery; A pulse power supply for applying a repetitive voltage pulse to said bias electrode, the pulse power supply having a negative polarity of the pulses; A grounded conductive electrode inserted through the inlet of the plastic container and disposed inside the container and supplying a hydrocarbon precursor gas into the container through the holes; And a gas supply device connected to the conductive electrode for supplying a hydrocarbon precursor gas into the plastic container through the conductive electrode.

In addition, the present invention provides a method for performing DLC coating on the inner wall of a plastic container by using the apparatus for DLC coating, a) disposing the plastic container inside the vacuum dielectric mill closed portion, the inside of the vacuum dielectric seal; Allowing the slotted bias electrode to be disposed around the periphery of the plastic container and then sealing the interior of the vacuum dielectric seal; b) introducing a grounded conductive electrode through the inlet of the plastic container into the container; c) pumping down the inside of the vacuum dielectric sealing part by using a vacuum pumping means connected to one side of the vacuum dielectric sealing part to bring down the vacuum pressure state; d) supplying a hydrocarbon precursor gas to the conductive electrode using a gas supply device to introduce the hydrocarbon precursor gas into the vessel through the holes of the conductive electrode; e) igniting a capacitively coupled plasma inside a plastic container by applying power from an RF power source to a spiral RF antenna disposed around the vacuum dielectric enclosure through a matching network; and f) applying repetitive negative voltage pulses to the bias electrode using a pulsed power supply.

Accordingly, according to the apparatus and method for DLC coating of the plastic container according to the present invention, DLC of excellent quality that can suppress the absorption of low-molecular organic compounds in the container while having excellent oxygen barrier properties on the inner wall of the plastic container The coating layer can be formed.

In particular, the use of the devices of the present invention operating in a closed loop production process enables low-volume production of recoverable plastic containers with DLC coating layers of excellent properties on the inner wall.

Hereinafter, the features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings. The terms or words used in the present specification and claims are consistent with the technical spirit of the present invention on the basis of the principle that the inventor can appropriately define the concept of the term in order to explain his invention in the best way. It should be interpreted as meaning and concept.

3A and 3B are schematic diagrams showing an embodiment of an inductively coupled plasma immersion ion implantation and deposition (ICP-PI3D) apparatus for forming a DLC coating layer on an inner wall of a plastic container according to the present invention, and FIG. 2 illustrates a slotted bias electrode in an inductively coupled plasma immersion ion implantation and deposition apparatus according to an embodiment of the present invention.

In addition, Figure 5 is a longitudinal cross-sectional view of a plastic container having a DLC coating layer on the inner wall according to the present invention, Figure 6 is an oscilloscope showing the pulse voltage and current during the process of forming a DLC coating layer using ICP-PI3D, 7 shows Raman spectra of a DLC coating layer formed using ICP-PI3D under different process conditions. FIG. 8 also shows a graph showing the value of the sheath capacitance per unit length and the sheath to target radius ratio rs / rt of the plasma density in the cylindrical shape in which the plasma is defined within a negatively biased cylindrical electrode. to be. The parameters used for the calculations are as follows: Vbias = 1.0 kV, Te = 3 eV, rt = 3 cm.

The present invention provides a capacitively coupled plasma immersion ion implantation and deposition (ICP-PI3D) apparatus for forming a barrier DLC (α-C: H) coating layer 2 on the inner wall of a plastic container 1 ( 100). The device 100 is a device for forming the DLC coating layer 2 on the inner wall of the plastic container 1, and as shown in FIGS. 3A and 3B, is detachable to accommodate the plastic container 1 to be treated. A vacuum dielectric chamber 110, the structure having a structure and dimensions, the portion of which has an inner wall shape and dimensions corresponding to the outline of the plastic container; A vacuum pumping means (120) connected to another part of the vacuum dielectric sealing part (110) to make the inside of the vacuum dielectric sealing part into a vacuum state; A spiral RF antenna (130) disposed around the vacuum dielectric seal (110); An RF power supply (140) connected to and applying power to the antenna through a matching network (141) to generate an RF current at the RF antenna (130); It has an outline and dimensions corresponding to the outline and dimensions of the plastic container 1 and is disposed along the periphery of the plastic container within the vacuum dielectric enclosure 110 and in response to the RF current induced by the RF antenna 130. A detachable slotted bias electrode 150 attached to prevent a short circuit along the circumference thereof; A pulse power supply (160) for applying a repetitive voltage pulse to the bias electrode (150), the polarity of the pulses being negative; A grounded conductive electrode (which is a gas supply electrode electrically connected to the ground) inserted through the inlet 1a of the plastic container 1 and disposed inside the container and supplying hydrocarbon precursor gas into the container through the holes 171. 170; And a gas supply device 180 connected to the conductive electrode 170 to supply the hydrocarbon precursor gas into the plastic container 1 through the conductive electrode.

3A and 3B, reference numeral 111 denotes an O-ring for sealing the inside of the vacuum dielectric seal 110.

In the DLC coating apparatus of the plastic container configured as described above, the vacuum dielectric sealing unit 110 is configured in a divided structure so that the plastic container 1 to be coated can be easily inserted therein. The interior space is to be sealed.

The plastic container 1 to be coated is put in the inner space sealed by the vacuum dielectric sealing part 110, and the inner space has an inner wall shape and dimensions corresponding to the outline of the plastic container 1.

In addition, one side of the vacuum dielectric sealing unit 110 has a structure that is connected to the vacuum pumping means 120, the vacuum internal means of the vacuum dielectric sealing unit 110 by the vacuum pumping means 120 is in a vacuum state It is supposed to be.

In addition, the vacuum dielectric encapsulation unit 110 may be made of a dielectric having at least a portion of which is transparent.

Here, when at least a portion of the vacuum dielectric seal 10 is made of a transparent dielectric, there is an advantage of visually observing the inside, more importantly OES (Optical Emission Spectroscopy) monitoring and control of the plasma process There is an advantage to being possible.

In view of this, it is possible to arbitrarily select a portion where the vacuum dielectric seal 10 can visually observe the plasma inside the plastic container 1 or a portion suitable for attaching the OES head and form a transparent dielectric. .

In this case, quartz or glass may be used as the transparent dielectric material, but a transparent polymer material such as transparent acrylic (PMMA), which is not easily broken, may be used, or the gas removal rate may be relatively low and high. Polyimide (PI) or polycarbonate (PC) having a glass transition temperature, and other known polymer materials capable of vacuum sealing may be used.

The vacuum pumping means 120 makes the sealed inner space of the vacuum dielectric sealing part 110 into a vacuum state by a suction action.

In addition, the bias electrode 150 is attached to prevent a short circuit along the circumference with respect to the RF current induced by the RF antenna 130, and is placed in the internal space of the vacuum dielectric sealing unit 110 and during the process. Is disposed along the outer periphery of the plastic container 1 in the interior space of the vacuum dielectric seal 110.

To this end, the bias electrode 150 has an outline and dimensions corresponding to the outline and dimensions of the plastic container 1.

In particular, the bias electrode 150 has a structure having one or more longitudinal slots 151 on the side wall and one or more radial slots 152 on the bottom surface, wherein the slots 151, 152 have a width a <dsh / 2. To have. Here, dsh is a thickness of a sheath formed near the inner wall of the plastic container 1 when a negative pulse voltage is applied to the bias electrode 150.

In addition, the bias electrode 150 should be provided so that at least a part or more of the contact with the outer wall of the plastic container 1, it is also provided to be cooled by a cooling fluid such as water.

Although not shown in the drawing for a cooling structure capable of cooling the bias electrode, a method of circulating the cooling fluid to the bias electrode may be applied to allow heat transfer and heat discharge from the bias electrode, and if water is If used, a conventional water-cooled structure for circulating the cooling water for a specific object may be applied.

For example, a wall section of the bias electrode is formed in a double wall structure, and then cooling water (cooling fluid) is passed into the double wall. To this end, it is necessary to install a cooling water line (cooling fluid line) connected to the inside of the double wall of the bias electrode, and supply and discharge the cooling water through the cooling water line to cool the bias electrode while the cooling water passes. If the inner space of the double wall is formed of a plurality of spaces separated from each other by connecting them in series or parallel to allow the coolant to circulate.

Of course, if the cooling water (cooling fluid) in addition to the above-described double-walled structure can pass through the bias electrode to enable heat exchange, it can be variously changed.

In addition, the conductive electrode 170 disposed inside the plastic container 1 is a gas supply electrode for supplying the gas supplied from the gas supply device 180 into the container, and from the outside of the vacuum dielectric seal 110 to the inside. In particular, it is inserted and installed long into the container through the container inlet (1a) in a grounded state.

At this time, the conductive electrode 170 is preferably installed to occupy less than 50% of the volume of the inner space of the container inside the container.

The grounded conductive electrode is inserted through the inlet of the container when installed inside the plastic container, which serves as a reference electrode to provide an optimum plasma potential inside the container and also allows precursor gas and support gas to enter the container through the holes. Will be supplied.

The conductive electrode is preferably installed along the axial direction of the container inside the plastic container for high plasma uniformity during the process, and preferably has a small enough area to reduce the plasma loss in the grounded portion. It is therefore desirable to occupy less than 50% of the volume of the interior space of the vessel, so that the surface area of the conductive electrode is as small as possible relative to the surface area of the vessel.

In the present invention, the conductive electrode 170 and the gas supply device 180 connected thereto are provided to supply the hydrocarbon precursor gas alone, or to supply the hydrocarbon precursor gas and the inertert gas together.

At this time, the hydrocarbon precursor gas as a process gas may be used a variety of gases containing a carbon element, for example toluene (C ₆ H ₅ CH ₃ ), acetylene (C ₂ H ₂ ), benzene (C ₆ H ₆ ), n- One selected from hexane (C ₆ H ₁₄ ), p-xylene (C ₈ H ₁₀ ), cyclohexane (C ₆ H ₂ ) can be used.

In addition, it is preferable to use argon which is inexpensive and has a low ionization potential as the inert support gas.

On the other hand, as a device for mass production of the plastic container 1 (see Fig. 5) having the DLC coating layer 2 on the inner wall, a closed loop of the device 100 for the two or more DLC coating having the above-described configuration It can be arranged in a loop) form.

In this case, the RF power supply 140 includes a single RF power supply having an RF matching network 141, and the RF antennas 130 constituting the device 100 for each DLC coating are included. Connected in parallel is configured to receive power from the single RF power supply 140 (see Figures 10-12).

10 is an equivalent electrical circuit diagram of an apparatus required for mass production of DLC-coated plastic containers including N ICP-PI3D according to one embodiment of the present invention connected in parallel and powered from a single RF power source. . FIG. 11 is a schematic diagram illustrating the powering of RF antennas of several ICP-PI3D devices from a single RF power supply for mass production of DLC coating layers of plastic containers according to an embodiment of the present invention, and FIG. A schematic diagram of a manufacturing line for the production of DLC coating layers of plastic containers comprising a number of ICP-PI3D devices arranged in a closed loop form according to one embodiment of the invention.

In the DLC coating apparatus 100 of the present invention configured as described above, when RF power is applied to the RF antenna 130, a high density hydrocarbon plasma is generated inside the plastic container 1, and the slotted electrode (slot is formed) By applying a negative high voltage pulse bias to the bias electrode 150, a hard DLC coating layer 2 is formed on the inner wall of the container 1 (see FIG. 5). Such a high density plasma ensures a short DLC formation time, and thus productivity can be increased. Independent control of the voltage bias and plasma parameters provides optimum process conditions, and thus good properties of the DLC coating layer with good repeatability are obtained.

On the other hand, in another aspect, the present invention provides a method for forming a DLC coating layer on the inner wall of the plastic container using ICP-PI3D.

That is, as a method of performing DLC coating on the inner wall of the plastic container 1 using the apparatus 100 for DLC coating described above, a) placing the plastic container 1 inside the vacuum dielectric seal 110; A step of placing a slotted bias electrode (150) around the periphery of the plastic container (1) in the vacuum dielectric seal (110) and then sealing the inside of the vacuum dielectric seal; b) introducing a grounded conductive electrode (170) through the inlet (1a) of the plastic container (1) into the container; c) pumping down the inside of the vacuum dielectric seal by using a vacuum pumping means (120) connected to one side of the vacuum dielectric seal (110) to a vacuum pressure state; d) supplying a hydrocarbon precursor gas to the conductive electrode 170 using a gas supply device 180 to introduce the hydrocarbon precursor gas into the vessel through the holes 171 of the conductive electrode; e) Capacitively coupled plasma inside the plastic container 1 by applying power from the RF power source 140 to the spiral RF antenna 130 disposed around the vacuum dielectric enclosure 110 via the matching network 141. Igniting; f) applying repetitive negative voltage pulses to the bias electrode 150 using a pulse power supply 160.

In the coating process of the present invention, in the case of step c), the vacuum pumping means 120 pumps down the inside of the vacuum dielectric sealing part to a pressure of 10 ⁻⁴ Torr or less.

In addition, in step d), to obtain a process pressure in the plastic container 1, the hydrocarbon precursor gas may be supplied alone, or the hydrocarbon precursor gas and the inert support gas may be supplied together. Alternatively, argon may be supplied together with a hydrocarbon precursor gas as an inert support gas.

In addition, in a preferred embodiment, the process pressure in the plastic container 1 may be a pressure of 0.2 mTorr ~ 20 mTorr.

Here, when the process pressure is less than 0.2 mTorr, it is difficult to ignite and maintain the ICP discharge, and the ratio of the process gas to the residual gas partial pressure cannot be maintained equally, which lowers the DLC coating quality. In addition, there is a problem that the deposition rate is too low.

On the other hand, if the concentration exceeds 20 mTorr, uniform ICP plasma cannot be obtained along the container surface, resulting in a problem of poor uniformity of the DLC coating.

Further, in step f), a negative voltage pulse having an amplitude in the range of 0.2 kV to 10 kV, a pulse width in the range of 0.3 kV to 10 kV, and a pulse repetition rate in the range of 0.1 kHz to 100 kHz may be applied, more preferably. Negative voltage pulses with amplitudes ranging from 0.5 kV to 5 kV, pulse widths from 1 kHz to 2 kHz, and pulse repetition rates from 5 kHz to 50 kHz can be applied.

Here, if the amplitude is too low, less than 0.2 kV, the quality of the DLC thin film in terms of hardness, adhesion, and pores may be deteriorated, and when the amplitude is greater than 10 kV, there is a problem of low power efficiency and overheating of the process.

It is also very difficult to obtain short pulse widths of less than 0.3 [mu] s for the pulse width range, and pulse widths exceeding 10 [mu] s are meaningless as the dielectric container surface is filled in the pulse by impinging ions. Too long pulses create a positive potential inside the vessel that can completely eliminate negative bias.

In addition, a low pulse repetition rate of less than 0.1 kHz has a problem of lowering the deposition rate and lowering productivity, and it is practically difficult to obtain a pulse repetition rate exceeding 100 kHz.

In this way, the DLC coating method of the present invention applies a sufficiently high negative pulse bias to the bias electrode due to the reduced dependence of the film properties on the distance between the bias electrode and the ground electrode and thus the coating of the coating layer throughout the container surface. Ensure equal properties

In addition, the present invention provides a method for low-volume production of a recoverable plastic container having a barrier DLC coating layer therein. This method of the present invention includes providing a number of ICP-PI3D devices operating in a closed loop production process.

In more detail, two or more DLC coating apparatus 100 is arranged in a closed loop form (see FIG. 12), wherein the RF power supply 140 is an RF matching network 141. It is provided with a single RF power source having a, and each of the RF antenna 130 constituting the device 100 for the DLC coating is configured to be connected in parallel to receive power from the single RF power supply 140 And continuously supplying uncoated plastic containers (1) to each device (100) for DLC coating in such a device for mass production of plastic containers having a DLC coating layer on the inner wall; Loading the plastic containers (1) into the device (100) for each DLC coating one by one; Proceed with the above coating process in the apparatus 100 for each DLC coating to perform a DLC coating on each plastic container (1).

In order to reduce manufacturing costs and improve the reliability of the hardware required to form DLC coatings in plastic containers, the possibility of using one RF power source in powering some ICP sources of the present invention is considered.

이고, 여기서 w는 권선의 수를, ξ는 안테나 길이 대 직경 비의 함수이다.FIG. 10 shows an apparatus for mass production of DLC-coated plastic containers including N ICP-PI3D device in which spiral RF antennas 130 of all ICP sources are connected in parallel and powered from a single RF power source 140. Equivalent electrical circuit diagram. Here, the antennas 130 each having an inductance Lant are connected to the RF power supply 140 through a matching network (MB) 141. The inductance of the spiral antenna 130

Where w is the number of turns and ξ is a function of the antenna length to diameter ratio.

The difference between the load impedance with and without plasma should be

(4)

(4)

If it is satisfied, it will be small.

Example 2:

d = 8 cm, l = 15 cm, then ξ = 4, w = 5, so Lant = 10 ^-7 × 25 × 8 × 10 ^-2 × 4 = 0.8 μH. The bias, plasma and geometrical parameters are as in Example 1, so the sheath capacitance is Csh = 6000 pF.

Then condition (4)

이면, 즉 f ~ 400kHz의 주파수가 사용되면, 조건(4)는 만족된다.

If, i.e., a frequency of f to 400 kHz is used, condition (4) is satisfied.

In this way, plastic containers having a DLC coating layer on the inner wall can be produced by using the apparatus and method of the present invention, wherein the DLC coating layer has good oxygen barrier properties and low molecular organic compounds are absorbed by the container. Will be suppressed.

Meanwhile, as another aspect of the present invention, a recoverable plastic container having a barrier DLC coating layer is disclosed, wherein the DLC coating layer has a nanohardness in the range of 5 GPa to 30 GPa, and has a thickness of 5 nm to 5000 nm. In this case, the plastic container may be a container made of polyethylene terephthalate (PET).

In the above, a specific preferred embodiment according to the present invention has been described. However, it is to be understood that the present invention is not limited to the above-described embodiments, and the above-described embodiments merely represent a part of various embodiments to which the principles of the present invention are applied. Those skilled in the art to which the present invention pertains may make various changes without departing from the spirit of the technical idea of the present invention described in the claims below.

1 is a schematic diagram of a conventional ICP source having a slotted cylindrical Faraday shield b and having an external spiral RF antenna a.

2 is a longitudinal sectional view showing a capacitively coupled plasma chemical vapor deposition (CCP-CVD) apparatus for forming a DLC coating layer on an inner wall of a plastic container according to one embodiment of the prior art.

3A and 3B are schematic diagrams showing an embodiment of an inductively coupled plasma immersion ion implantation and deposition (ICP-PI3D) apparatus for forming a DLC coating layer on an inner wall of a plastic container according to the present invention.

4 is a view showing a slotted bias electrode in an inductively coupled plasma immersion ion implantation and deposition apparatus according to an embodiment of the present invention.

5 is a longitudinal sectional view of a plastic container having a DLC coating layer on an inner wall according to the present invention.

FIG. 6 is an oscilloscope showing pulse voltage and current during the process of forming a DLC coating layer using ICP-PI3D.

FIG. 7 is a diagram illustrating a Raman spectra of a DLC coating layer formed using ICP-PI3D under different process conditions.

FIG. 8 is a graph showing the Child sheath to target radius ratio rs / rt and the value of sheath capacitance per unit length for plasma density in a cylindrical shape in which the plasma is defined within a negatively biased cylindrical electrode. The parameters used for the calculation are as follows: Vbias = 1.0 kV, Te = 3 eV, rt = 3 cm.

FIG. 9 is an equivalent electrical circuit diagram of a device required for mass production of DLC-coated plastic containers including N CCP-CVD prior art devices connected in parallel and powered from a single RF power source.

10 is an equivalent electrical circuit diagram of an apparatus required for mass production of DLC-coated plastic containers including N ICP-PI3D according to one embodiment of the present invention connected in parallel and powered from a single RF power source.

FIG. 11 is a schematic illustration of the powering of RF antennas of several ICP-PI3D devices from a single RF power supply for mass production of DLC coating layers of plastic containers according to one embodiment of the present invention.

12 is a schematic diagram of a manufacturing line for DLC coating layer production of plastic containers including a number of ICP-PI3D devices arranged in a closed loop form according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

1: plastic container 1a: inlet

2: DLC coating layer

100: Device for DLC coating

      (Capacitively coupled plasma immersion ion implantation and deposition apparatus)

110: vacuum dielectric sealing portion 120: vacuum pumping means

130: RF antenna 140: RF power supply

141: matching network 150: bias electrode

151, 152: slot 160: pulse power supply

170: conductive electrode 171: hole

180: gas supply device

Claims (20)

An apparatus for forming a DLC coating layer (2) on the inner wall of the plastic container (1), A vacuum dielectric seal 110 having a detachable structure for accommodating the plastic container 1, the vacuum dielectric sealing part 110 having a portion having an inner wall shape and dimensions corresponding to an outline of the plastic container 1; A vacuum pumping means (120) connected to another part of the vacuum dielectric sealing part (110) to make the inside of the vacuum dielectric sealing part (110) in a vacuum state; A spiral RF antenna (130) disposed around the vacuum dielectric seal (110); An RF power supply (140) connected to and applied power to the RF antenna (130) through a matching network (141) to generate an RF current in the RF antenna (130); It has an outline and dimensions corresponding to the outline and dimensions of the plastic container 1 and is disposed along the periphery of the plastic container within the vacuum dielectric enclosure 110 and in response to the RF current induced by the RF antenna 130. A detachable slotted bias electrode 150 attached to prevent a short circuit along the circumference thereof; A pulse power supply (160) for applying a repetitive voltage pulse to the bias electrode (150), the polarity of the pulses being negative; A grounded conductive electrode 170 inserted and disposed in the plastic container 1 and supplying a hydrocarbon precursor gas into the plastic container 1 through the holes 171; A gas supply device 180 connected to the conductive electrode 170 to supply a hydrocarbon precursor gas; Apparatus for DLC coating of a plastic container comprising a. The method according to claim 1, The vacuum dielectric seal (110) is a device for DLC coating of a plastic container, characterized in that at least a portion of the area is made of a transparent dielectric. The method according to claim 2, And said transparent dielectric is selected from quartz, glass, acrylic (PMMA), polyimide (PI), and polycarbonate (PC). The method according to claim 1, The bias electrode (150) is a device for DLC coating of the plastic container, characterized in that at least a portion is installed in contact with the outer wall of the plastic container (1). The method according to claim 1, The bias electrode (150) is an apparatus for DLC coating of a plastic container, characterized in that cooled by the cooling fluid passing through to enable heat transfer. The method according to claim 1, The bias electrode 150 has a structure having one or more longitudinal slots 151 on the side wall and one or more radial slots 152 on the bottom surface thereof. The slots 151 and 152 have a width a < dsh / 2, where dsh is a sheath formed near the inner wall of the plastic container 1 when a negative pulse voltage is applied to the bias electrode 150. Apparatus for DLC coating of plastic containers, characterized in that the thickness. The method according to claim 1, The conductive electrode (170) is a device for DLC coating of a plastic container, characterized in that installed in the interior of the plastic container (1) occupy less than 50% of the volume of the inner space of the container. The method according to claim 1, Apparatus for mass production of plastic containers (1) having a DLC coating layer (2) on the inner wall, The apparatus 100 for two or more DLC coating having the above configuration is arranged in a closed loop form, The RF power supply 140 has a single RF power supply having an RF matching network 141, RF antenna 130 constituting the apparatus 100 for each DLC coating is connected in parallel and configured to receive power from the single RF power supply 140 for the DLC coating of the plastic container Device. The method according to claim 1, The grounded conductive electrode 170 and the gas supply device 180 connected thereto are provided to supply the hydrocarbon precursor gas alone or to supply the hydrocarbon precursor gas and the inertert gas together. Device for the DLC coating. The method according to claim 9, The hydrocarbon precursor gas is toluene (C ₆ H ₅ CH ₃ ), acetylene (C ₂ H ₂ ), benzene (C ₆ H ₆ ), n-hexane (C ₆ H ₁₄ ), p- xylene (C ₈ H ₁₀ ) , And cyclohexane (C ₆ H ₂ ). Apparatus for DLC coating of plastic containers. A method of performing a DLC coating on an inner wall of a plastic container using the apparatus for DLC coating of any one of claims 1 to 10. a) placing a plastic container inside the vacuum dielectric seal, wherein a slotted bias electrode is disposed around the periphery of the plastic container within the vacuum dielectric seal and then sealing the interior of the vacuum dielectric seal; b) inserting and placing a grounded conductive electrode into the plastic container; c) making the inside of the vacuum dielectric seal part into a vacuum state by using a vacuum pumping means connected to one side of the vacuum dielectric seal part; d) supplying a hydrocarbon precursor gas into a plastic container through the conductive electrode using a gas supply device; e) igniting a capacitively coupled plasma inside a plastic container by applying power from an RF power source to a spiral RF antenna disposed around the vacuum dielectric enclosure through a matching network; f) applying a repetitive negative voltage pulse to said bias electrode using a pulsed power supply; Method for DLC coating of a plastic container comprising a. The method of claim 11, The method for DLC coating of the plastic container, characterized in that the step c) to make the interior of the vacuum dielectric seal in a vacuum state of less than 10 ^-4 Torr. The method of claim 11, And d) supplying a hydrocarbon precursor gas alone or a hydrocarbon precursor gas and an inertert support gas together to obtain a process pressure in the plastic container in step d). 14. The method of claim 13, The hydrocarbon precursor gas is toluene (C ₆ H ₅ CH ₃ ), acetylene (C ₂ H ₂ ), benzene (C ₆ H ₆ ), n-hexane (C ₆ H ₁₄ ), p- xylene (C ₈ H ₁₀ ) , And cyclohexane (C ₆ H ₂ ). The method according to claim 13 or 14, Process pressure in the plastic container is 0.2 mTorr ~ 20 mTorr method for DLC coating of the plastic container, characterized in that. The method of claim 11, DLC of the plastic container, in step f), applying a negative voltage pulse having an amplitude in the range of 0.2 kV to 10 kV, a pulse width in the range of 0.3 kV to 10 kV, and a pulse repetition rate in the range of 0.1 kHz to 100 kHz. Method for coating. The method of claim 11, DLC of the plastic container, in step f), applying a negative voltage pulse having an amplitude in the range of 0.5 kV to 5 kV, a pulse width in the range of 1 kHz to 2 kHz, and a pulse repetition rate in the range of 5 kHz to 50 kHz. Method for coating. The method of claim 11, A method for mass production of plastic containers with a DLC coating on the inner wall, Arranged in the form of a closed loop device for at least two DLC coating, In the case of the RF power supply has a single RF power supply having an RF matching network, RF antennas constituting the device for each of the DLC coatings are connected in parallel to receive power from the single RF power supply, Continuously feeding the uncoated plastic containers to a device for each DLC coating; Loading the plastic containers one by one into a device for each DLC coating; Carrying out the process according to claim 11 in an apparatus for each DLC coating to perform DLC coating on each plastic container; Method for DLC coating of plastic containers, characterized in that proceeding. A recoverable plastic container having a barrier DLC coating layer prepared according to the method of claim 11, wherein the DLC coating layer has a nanohardness in the range of 5 GPa to 30 GPa and has a thickness of 5 nm to 5000 nm. Recoverable plastic container. The method of claim 19, A recoverable plastic container made of polyethylene terephthalate (PET) having said barrier DLC coating layer.

Images