JP2007261077A - Dlc-film-coated biodegradable plastic container or film and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biodegradable plastic container or film having a gas-barrier thin film, e.g. a DLC film, on the surface whose gas-barrier performance is comparable with or higher than those of the uncoated PET bottles and films and the adhesion of whose gas-barrier film is improved to a practical level. <P>SOLUTION: A method of manufacturing the DLC-film-coated biodegradable plastic container or film has a process of forming a middle film of a thickness of 0.5-20 nm based on at least one constituent elements of carbon, silicon and aluminum on the surface of a container or film made of a biodegradable plastic by the use of a raw material containing a compound composed of single bonds alone and a process of forming a DLC film or a silicon-containing DLC film on the middle film by the use of a raw material containing a compound having a double or a triple bond. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for imparting gas barrier properties by coating a DLC film on a plastic container or film formed of a biodegradable plastic.

  In recent years, attention has been focused on polylactic acid, which is a biodegradable plastic, due to increasing interest in the environment. In addition, there is a disclosure of a technique for providing a gas barrier property by forming a DLC film on the surface of a plastic container formed of a biodegradable plastic (see, for example, Patent Document 1 or 2).

  Patent Document 1 discloses a container in which a DLC film is deposited on the inner surface of a polylactic acid plastic container, for example.

  In Patent Document 2, a carbon film, particularly a carbon film containing a bond with hydrogen is formed on the inner surface of a polylactic acid plastic container by plasma chemical vapor deposition using acetylene as a source gas, for example, 0.03 μm to 0.2 μm There is a disclosure of a container coated with the following film thickness.

JP 2002-274521 A JP-A-2005-14966

  However, referring to Table 2 of Patent Document 1, the improvement rate of the gas barrier property comparing the PLA (polylactic acid) single bottle and the PLA bottle formed with the DLC film is at most 1.7 to 2.3 times. It is hard to say that the gas barrier properties are sufficiently improved.

  FIG. 3 of Patent Document 2 shows a comparison of weight loss for one month when water is filled in a polylactic acid bottle in which a carbon film containing a bond between a single polylactic acid bottle and hydrogen is formed. ing. Here, the result shows that the weight loss of water is reduced by about one-half by applying a carbon film containing a bond with hydrogen, but it is said that the gas barrier property is sufficiently improved as well. It's hard.

  Furthermore, as a result of coating the DLC film by the plasma CVD method using acetylene as a raw material gas on a container formed of polylactic acid, the present inventor has a level of adhesion between the polylactic acid and the DLC film that cannot be practically used. It was found that the DLC film peeled off when touched. In Patent Documents 1 and 2, the adhesiveness has not been studied, but it is considered that the adhesiveness between the polylactic acid and the DLC film is not yet at a practical level if estimated from the results of the present inventors.

  In general, in the beverage container market, when polylactic acid is used as a container base material, the target is to improve the gas barrier property to the same level or higher than that of a normal polyethylene terephthalate (PET) bottle. Therefore, the present inventor aims to improve both gas barrier properties and film adhesion by coating a DLC film on a container formed of polylactic acid, and to a container formed of polylactic acid other than acetylene. Various raw material gases were changed, and film formation was performed using, for example, ethylene (double bond raw material), styrene, toluene (cyclic structure raw material), and methane (single bond raw material). However, it was found that the gas barrier property comparable to that of a normal uncoated PET bottle cannot be obtained by using any of the raw materials only by performing a plasma treatment for several seconds.

  The reason why the adhesion and gas barrier properties are not sufficient is that when a thin film is formed on the surface of a polylactic acid container by plasma CVD using a source gas having a double bond or a triple bond, the polylactic acid cleavage reaction Presumed to be dominant.

  On the other hand, it was found that methane, which is a raw material of a single bond compound having only a single bond, obtained film adhesion, but the film formation rate was slow and the improvement in gas barrier properties was insufficient.

  The present invention relates to a container or film formed of a biodegradable plastic having a DLC film or a silicon-containing DLC film formed on the surface thereof, and has a gas barrier property equivalent to or higher than that of an uncoated PET bottle or uncoated PET film, and An object of the present invention is to provide a method for producing them capable of improving the adhesion of the film to a practical level.

  The present invention also provides a DLC film-coated biodegradable plastic that has a gas barrier property equal to or higher than that of an uncoated PET bottle or uncoated PET film and has improved film adhesion to a practical level as described above. The object is to provide a container or film.

  The present inventor has earnestly researched and developed to solve the above problem, and after forming an intermediate film serving as an adhesion layer on the surface of the biodegradable plastic by a plasma CVD method using a compound having only a single bond as a raw material, The present inventors have found that the above problems can be solved by forming a DLC film using a raw material of a double bond compound or a triple bond compound that can provide gas barrier properties, and has completed the present invention. That is, the DLC film-coated biodegradable plastic container or film manufacturing method according to the present invention uses a raw material containing a compound in which carbon, silicon, or aluminum is a main constituent element and the constituent elements are bonded by a single bond. An intermediate film having a thickness of 0.5 to 20 nm and containing at least one of carbon, silicon, and aluminum as a main constituent element on the surface of a container or film formed of biodegradable plastic by plasma CVD. And using a raw material containing at least one of acetylene-based hydrocarbon, ethylene-based hydrocarbon, aromatic hydrocarbon, or silicon-containing hydrocarbon having a double bond or triple bond, a plasma CVD method Forming a DLC film or a silicon-containing DLC film on the intermediate film. To.

  The method for producing a DLC film-coated biodegradable plastic container or film according to the present invention includes a case where polylactic acid is used as the biodegradable plastic. Among the biodegradable plastics, polylactic acid has many advantages such as (1) relatively low cost, (2) can be formed into bottles, and (3) can be produced from plant-derived raw materials.

  In the DLC film-coated biodegradable plastic container or film manufacturing method according to the present invention, polylactic acid is used as the biodegradable plastic, methane gas is used as the raw material in the step of forming the intermediate film, and The thickness of the intermediate film is preferably 1.2 to 1.8 nm. Adhesion and gas barrier properties can be balanced.

The DLC film-coated biodegradable plastic container or film according to the present invention is a DLC film-coated biodegradable plastic in which a DLC film or a silicon-containing DLC film is formed on the surface of a container or film formed of the biodegradable plastic. The container or film is characterized in that the DLC film or the silicon-containing DLC film has adhesion strength at which peeling of the majority is not observed by the cross-cut tape method of JISK5400 in Condition 1.
Condition 1: The gap between the cuts is 1 mm, and the number of squares is 100.

  In the DLC film-coated biodegradable plastic container or film according to the present invention, a thickness of 0.5 is between the surface of the container or film formed of the biodegradable plastic and the DLC film or the silicon-containing DLC film. It is preferable to provide an intermediate film having carbon and hydrogen or carbon, silicon and hydrogen as main constituent elements at ˜1.8 nm.

In the DLC film-coated biodegradable plastic container or film according to the present invention, a thickness of 0.5 is between the surface of the container or film formed of the biodegradable plastic and the DLC film or the silicon-containing DLC film. It is preferable to provide an intermediate film mainly composed of a metal oxide at ˜20 nm. By providing such an intermediate film, both adhesion and gas barrier properties can be balanced. Here, the metal oxide is preferably silicon oxide SiO _x (where 1 ≦ x ≦ 2) or aluminum oxide AlO _x (where 0.75 ≦ x ≦ 1.5).

  The DLC film-coated biodegradable plastic container or film according to the present invention includes that the biodegradable plastic is polylactic acid. Among the biodegradable plastics, polylactic acid has many advantages such as (1) relatively low cost, (2) can be formed into bottles, and (3) can be produced from plant-derived raw materials.

  In the present invention, for a container or film formed of biodegradable plastic having a DLC film or a silicon-containing DLC film formed on the surface, the gas barrier property is equal to or greater than that of an uncoated PET bottle or uncoated PET film, and The film adhesion was improved to a practical level.

  Hereinafter, the present invention will be described in detail with reference to embodiments, but the present invention is not construed as being limited to these descriptions.

First, the DLC film coating biodegradable plastic container forming apparatus used in this embodiment will be briefly described. FIG. 1 is a schematic view showing an embodiment of a film forming apparatus for coating a DLC film on the inner wall surface of a plastic container. The film forming apparatus shown in FIG. 1 is configured such that, for example, in the film forming apparatus described in Patent Document 3, two types of source gases can be sent into the vacuum chamber 6. That is, the film forming apparatus of FIG. 1 includes the external electrode 3, the internal electrode 9, the first source gas supply unit 18 a, the second source gas supply unit 18 b, the matching box 12, and the vacuum chamber 6. A high-frequency power source 13 and an exhaust pump 20.
JP-A-8-53117

  The external electrode 3 constitutes a vacuum chamber 6 together with the conductive lid portion 5 and the insulating portion 4. An insulating part 4 is arranged under the lid part 5, and an external electrode 3 is arranged under the insulating part 4. The external electrode 3 includes an upper external electrode 2 and a lower external electrode 1. An O-ring 8 is appropriately disposed between each, and the vacuum chamber 6 can be sealed.

  A space is formed inside the external electrode 3, and a container 7 formed of a biodegradable plastic to be coated is accommodated. The insulating portion 4 and the lid portion 5 are provided with an opening portion that leads to the space of the external electrode 3, and the space 40 inside the lid portion 5 is connected to the space inside the external electrode 3 through the opening portion. .

  The matching box 12 is connected to the lower external electrode 1, and the matching box 12 is further connected to a high frequency power source (RF power source) 13.

  The high frequency power source 13 generates a high frequency which is energy for converting the raw material gas into plasma. The frequency of the high-frequency power source is 100 kHz to 1000 MHz, and for example, an industrial frequency of 13.56 MHz is used.

  The internal electrode 9 is disposed in the external electrode 3 and is disposed in the container 7. The internal electrode 9 has a hollow tube shape inside. At the tip of the internal electrode 9, a gas outlet 9a for the source gas is provided. The internal electrode 9 is grounded.

  The first source gas supply means 18 a introduces the first source gas supplied from the first source gas generation source 17 a into the container 7 through the pipe 16 a to the vacuum chamber 6. On the other hand, the second source gas supply means 18 b introduces the second source gas supplied from the second source gas generation source 17 b into the container 7 through the pipe 16 b to the vacuum chamber 6. Piping is assembled so that the first source gas and the second source gas can be switched and supplied into the vacuum chamber 6.

Next, when the DLC film is coated on the biodegradable plastic film, for example, the film is formed using the equipment disclosed in Patent Document 4.
Japanese Patent No. 3176558

  A method for producing a DLC film-coated biodegradable plastic container according to this embodiment will be described with reference to the film forming apparatus shown in FIG. In addition, about the manufacturing method of the DLC film coating biodegradable plastic film which concerns on this embodiment, although the film forming apparatus for film vapor deposition different from the film-forming apparatus of FIG. 1 will be used, since a process is common, A case where film formation is performed on a biodegradable plastic container will be described as an example. Examples of containers include one-way or returnable beverage containers and food containers filled with carbonated beverages, sparkling beverages, and the like. An example of the film is a film that is processed and used for packaging purposes.

  The method for manufacturing a DLC film-coated biodegradable plastic container according to this embodiment uses a raw material containing a compound in which carbon, silicon, or aluminum is a main constituent element and the constituent elements are bonded by a single bond, and plasma is used. An intermediate film having a thickness of 0.5 to 20 nm and containing at least one of carbon, silicon, and aluminum as a main constituent element is formed on the surface of a container or film formed of biodegradable plastic by CVD. And using a raw material containing at least one of acetylene hydrocarbon, ethylene hydrocarbon or aromatic hydrocarbon or silicon-containing hydrocarbon having a double bond or triple bond, by the plasma CVD method, Forming a DLC film or a silicon-containing DLC film on the intermediate film. Hereinafter, it demonstrates concretely in order of a process.

(Gas replacement process)
First, the vacuum valves 25a and 25b and a vacuum valve (not shown) are opened to open the vacuum chamber 6 to the atmosphere. Next, the lower external electrode 1 and the upper external electrode 2 are disassembled, the container 7 is installed in the space in the vacuum chamber 6, and the vacuum chamber 6 is sealed.

  In the present embodiment, a biodegradable plastic container or film is used as the container 7 or film (not shown). A biodegradable plastic is a polymer that is decomposed in vivo or by the action of microorganisms, and is decomposed into water, carbon dioxide, methane, and the like by hydrolysis. There are natural polymers and synthetic polymers. Examples of natural polymers include proteins and polysaccharides such as collagen and starch, and examples of synthetic polymers include aliphatic polyesters such as polyglycolic acid, polylactic acid, and polyethylene succinate. In this embodiment, polylactic acid (PLA) is particularly preferable from the viewpoint of water resistance and economy.

  Next, after closing the vacuum valves 25a and 25b and a vacuum valve (not shown), the vacuum valve 19 is opened, the exhaust pump 20 is operated, and the vacuum chamber 6 is evacuated. The pressure in the vacuum chamber 6 at this time is 1.33 to 13.3 Pa.

(Interlayer film formation process)
Next, while continuing the exhaust, the first source gas is supplied by the first source gas supply means 18 a and blown out from the gas outlet 9 a through the internal electrode 9. Thereby, the first source gas is introduced into the container 7. While replacing the inside of the container 7 with the first source gas, the inside of the container 7 is adjusted to a film forming pressure of the intermediate film, for example, about 6.6 to 66 Pa.

  In the present embodiment, the first source gas that is the source gas of the intermediate film mainly includes a compound in which carbon, silicon, or aluminum is a main constituent element, and the constituent elements are bonded by a single bond, and the compound is used alone. You may use as source gas.

  A compound in which carbon is a main constituent element and the constituent elements are bonded by a single bond is, for example, a methane-based hydrocarbon. Examples of the methane hydrocarbon include methane, ethane, propane, and butane. In addition, hydrocarbons containing elements other than carbon and hydrogen, such as methanol and acetone, are also included in the hydrocarbons of the present invention unless they contain either a carbon double bond or a carbon triple bond.

  A compound in which carbon and silicon are main constituent elements and the constituent elements are bonded by a single bond is a single-bond silicon-containing hydrocarbon, for example, hexamethyldisilane, vinyltrimethylsilane, methylsilane, dimethyl Silane, trimethylsilane, diethylsilane, propylsilane, methyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, octa An organic silane compound such as methylcyclotetrasiloxane, 1,1,3,3-tetramethyldisiloxane and aminosilane, or an organic siloxane compound such as hexamethyldisiloxane (HMDSO).

  A compound in which silicon is a main constituent element and the constituent elements are bonded by a single bond is a single-bond silicon compound, for example, a compound having no alkyl group such as silane or silicon tetrachloride. .

  A compound in which aluminum is a main constituent element and the constituent elements are bonded by a single bond is a single-bonded aluminum compound, such as aluminum chloride.

A compound in which carbon and aluminum are main constituent elements and the constituent elements are bonded by a single bond is a single-bonded aluminum-containing hydrocarbon, and R ₃ -Al, R ₂ -Al-X, R There are organoaluminum compounds such as —Al—X ₂ (wherein R is an alkyl group, X is hydrogen, halogen, alkoxy, amide group, etc.). For example, trialkylaluminum, trimethylaluminum, and triethylaluminum are dialkylaluminum, triisopropylaluminum, and tri-n-butylaluminum. Further, it may have a structure of (RO) ₃ -Al, (RO) ₂ -Al-R ', (RO) -Al-R ₂ ', for example, dimethylisopropylaluminum may be used.

  The first source gas is methane-based hydrocarbon, single-bonded silicon compound, single-bonded silicon-containing hydrocarbon, single-bonded aluminum compound, single-bonded aluminum-containing hydrocarbon. Used in a mixture of two or more or diluted with an inert gas. For example, a silicon-containing DLC film may be used as an intermediate film by appropriately adding a compound having no alkyl group such as silane or silicon tetrachloride to a methane hydrocarbon raw material.

  Next, an RF output (for example, 13.56 MHz, 300 to 1200 W) is supplied from the high frequency power supply 13 to the external electrode 3 via the matching box 12, and the first source gas is converted into plasma in the vacuum chamber 6. Thereby, an intermediate film is formed on the inner surface of the container 7. The film formation time is about 0.1 to 5 seconds. Then, the supply of the first source gas is terminated. Subsequently, when the process proceeds to the next step and a DLC film or a silicon-containing DLC film is formed, the RF output may remain supplied.

The composition of the intermediate film is determined by the component of the first source gas, and at least one of carbon, silicon, and aluminum is a main constituent element. For example, the intermediate film is a DLC film, a silicon-containing DLC film, or SiO _x (where 1 ≦ x ≦ 2, hereinafter referred to simply as SiO _x ) or AlO _x (however, 0.75 ≦ x ≦ 1.5, hereinafter referred to simply as AlO _x ) is there. The intermediate film may contain carbon atoms, oxygen atoms, and nitrogen atoms separately from the main component. The main component means a component that occupies more than half of the constituent atoms excluding hydrogen atoms. In the case of an intermediate film mainly composed of a metal oxide, for example, the total number of atoms of oxygen and silicon is , When the total number of atoms of carbon and nitrogen is greater. The thickness of the intermediate film is sufficient, for example, as long as the acetylene plasma cannot react directly with the polylactic acid substrate, and is 0.5 to 20 nm. When the intermediate film is a DLC film or a silicon-containing DLC film, the thickness is preferably 0.5 to 1.8 nm. It is presumed that when a film is formed by plasma CVD using a raw material having a double bond or triple bond on the surface of a biodegradable plastic, especially polylactic acid, a cutting reaction occurs and the adhesion of the film cannot be obtained. Is done. The present inventor presumes that the cleavage reaction can be suppressed by using a raw material in which constituent elements are bonded only by a single bond, and as a result, film adhesion is obtained. However, on the other hand, it has been found that when a raw material in which constituent elements are bonded only by a single bond is used, the film formation rate is low, and it takes time to reach a film thickness that provides gas barrier properties. Therefore, a DLC film or a silicon-containing DLC is mainly used as a gas barrier layer for the purpose of first forming an intermediate film as an adhesion layer on the surface of a biodegradable plastic, particularly polylactic acid, and then providing gas barrier properties. A film was formed. Therefore, when the film thickness of the intermediate film is less than 0.5 nm, the adhesion of the DLC film or silicon-containing DLC film serving as the gas barrier layer cannot be obtained, and when it exceeds 20 nm, the entire film formation time becomes long. The film thickness of the intermediate film is preferably 1.2 to 1.8 nm when methane is used as the first source gas, and at this time, a high gas barrier property can be imparted particularly to the container or the film.

(DLC film or silicon-containing DLC film deposition process)
Subsequently, the second source gas is supplied by the second source gas supply means 18 b and blown out from the gas outlet 9 a through the internal electrode 9. Thereby, the second source gas is introduced into the container 7. While replacing the inside of the container 7 with the second source gas, the inside of the container 7 is adjusted to a film forming pressure of, for example, about 6.6 to 66 Pa.

  In the present embodiment, the second source gas that is the source gas of the DLC film or silicon-containing DLC film is acetylene-based hydrocarbon, ethylene-based hydrocarbon, aromatic hydrocarbon, or silicon-containing hydrocarbon having a double bond or triple bond. A raw material mainly containing at least one of the above.

  Examples of the acetylenic hydrocarbon include acetylene, methylacetylene, and ethylacetylene. Examples of the ethylene hydrocarbon include ethylene, propylene, and butylene. Examples of the aromatic hydrocarbon include benzene, toluene, and xylene. Examples of the silicon-containing hydrocarbon having a double bond or a triple bond include organosilane compounds such as phenylsilane and phenyltrimethoxysilane.

  The second source gas is acetylene hydrocarbon, ethylene hydrocarbon, aromatic hydrocarbon, silicon-containing hydrocarbon having a double bond or triple bond, or a mixture of two or more of these, or Dilute with inert gas. Note that a silicon-containing DLC film may be formed by appropriately adding a compound having no alkyl group such as silane or silicon tetrachloride to an acetylene hydrocarbon raw material.

  Next, an RF output (for example, 13.56 MHz, 300 to 1200 W) is supplied to the external electrode 3 from the high frequency power supply 13 through the matching box 12, and the second source gas, for example, acetylene is converted into plasma in the vacuum chamber 6. The supply of the RF output may be started after the introduction of the second source gas, or the RF output may be continuously supplied from the intermediate film forming step. A DLC film or a silicon-containing DLC film is formed on the intermediate film by plasma CVD. The film formation time is about 1 to 5 seconds. Then, the supply of the second source gas is finished and the supply of the RF output is finished.

  In the present invention, not only a high-frequency power source but also a microwave power source may be used as means for converting the source gas into plasma. For example, 2.45 GHz is supplied as the microwave.

The composition of the film forming process of the DLC film or the silicon-containing DLC film is determined by the component of the second source gas. The DLC film or the silicon-containing DLC film may contain oxygen atoms or nitrogen atoms. The DLC film is a film called an i-carbon film or a hydrogenated amorphous carbon film (aC: H). A carbon film having a hydrogen content of 0 to 67% including a hard carbon film and a polymer-like carbon is used. Say. The DLC film is an amorphous carbon film and also has SP ³ bonds. The film thickness of the DLC film or silicon-containing DLC film is preferably 7 to 100 nm. If it is thinner than 7 nm, gas barrier properties may be insufficient. On the other hand, the film thickness may be thicker than 100 nm, but microcracks may occur, and the thickness is preferably set to 100 nm or less in view of the obtained gas barrier property. Since the DLC film or the silicon-containing DLC film is formed after an intermediate film is provided on the surface of biodegradable plastic, especially polylactic acid, it is exposed to a compound plasma having a double bond or a triple bond such as acetylene. Since an intermediate film is formed, the biodegradable plastic is less likely to cause a cutting reaction, and the adhesion of the film is improved. In addition, since the second source gas having a double bond or a triple bond has a high film forming speed, it does not take time to obtain a film thickness that provides gas barrier properties, and thus has high productivity.

(Finished film)
Next, the RF output from the high frequency power supply 13 is stopped, the vacuum valve 25b is closed, and the supply of the second source gas is stopped. The inside of the vacuum chamber 6 is opened to the atmosphere, and the container 7 is taken out.

The following container is obtained by the method for producing a DLC film-coated biodegradable plastic container or film according to this embodiment. That is, in a DLC film-coated biodegradable plastic container or film in which a DLC film or a silicon-containing DLC film is formed on the surface of a container or film formed of a biodegradable plastic, the DLC film or the silicon-containing DLC film is It is a container having adhesion strength in which peeling is not observed in the majority of the majority by the cross tape method of JISK5400 in Condition 1.
Condition 1: The gap between the cuts is 1 mm, and the number of squares is 100.
In addition, the DLC film-coated biodegradable plastic container or film according to this embodiment has a gas barrier property equivalent to that of an uncoated PET container or uncoated PET film when compared with a container or film having the same shape.

  Using a polylactic acid film having a thickness of 200 μm, an intermediate film was first formed on one surface by plasma CVD, and then a DLC film was formed by plasma CVD.

(Evaluation methods)
(1) Oxygen permeability The oxygen permeability of this film is OXTRAN manufactured by Modern Control.
Using 2/20, measurement was performed under the conditions of 23 ° C. and 90% RH, and the measured value after 20 hours from the start of measurement was described.
(2) Film thickness The film thickness was measured using DEKTAK3 manufactured by Veeco.
(3) Adhesion test A test was conducted to determine whether or not the DLC film was peeled off by the cross-cut tape method of JISK5400 under Condition 1. It was divided into 100 by cutting and evaluated as the ratio of the number that was not peeled off by the tape. The higher the ratio of the number that has not been peeled off, the better the adhesion.
Condition 1: The gap between the cuts is 1 mm, and the number of squares is 100.

(Experiment 1)
An intermediate film was formed using methane gas as the first source gas at a gas flow rate of 60 sccm and a high frequency output of 600 W. The film formation time at this time was 2 seconds. The thickness of the intermediate film was 1.14 nm. Next, acetylene was used as the second source gas at a gas flow rate of 80 sccm. A DLC film was formed with a high frequency output of 1000 W. The film formation time at this time was 2 seconds. The total thickness of the film including the intermediate film was 20 nm. The oxygen transmission rate was 43.36 cc / m ² / day. According to the adhesion test, the percentage that did not peel off was 56%. The relationship between the film thickness of the intermediate film and the oxygen permeability is shown in FIG. FIG. 3 shows the relationship between the film thickness of the intermediate film and the ratio that was not removed by the adhesion test.

(Experiment 2)
An intermediate film was formed using methane gas as the first source gas at a gas flow rate of 80 sccm and a high frequency output of 600 W. The film formation time at this time was 2 seconds. The film thickness of the intermediate film was 1.22 nm. Next, a DLC film was formed on the intermediate film under the same conditions as in Experiment 1. The total thickness of the film including the intermediate film was 20 nm. The oxygen transmission rate was 36.53 cc / m ² / day. According to the adhesion test, the percentage not peeled off was 55%. The relationship between the film thickness of the intermediate film and the oxygen permeability is shown in FIG. FIG. 3 shows the relationship between the film thickness of the intermediate film and the ratio that was not removed by the adhesion test.

(Experiment 3)
An intermediate film was formed using methane gas as the first source gas at a gas flow rate of 120 sccm and a high frequency output of 600 W. The film formation time at this time was 1 second. The thickness of the intermediate film was 0.73 nm. Next, a DLC film was formed on the intermediate film under the same conditions as in Experiment 1. The total thickness of the film including the intermediate film was 20 nm. The oxygen transmission rate was 51.60 cc / m ² / day. According to the adhesion test, the percentage not peeled off was 51%. The relationship between the film thickness of the intermediate film and the oxygen permeability is shown in FIG. FIG. 3 shows the relationship between the film thickness of the intermediate film and the ratio that was not removed by the adhesion test.

(Experiment 4)
An intermediate film was formed using methane gas as the first source gas at a gas flow rate of 120 sccm and a high frequency output of 600 W. The film formation time at this time was 2 seconds. The film thickness of the intermediate film was 1.46 nm. Next, a DLC film was formed on the intermediate film under the same conditions as in Experiment 1. The total thickness of the film including the intermediate film was 21 nm. The oxygen transmission rate was 28.96 cc / m ² / day. According to the adhesion test, the percentage that did not peel off was 60%. The relationship between the film thickness of the intermediate film and the oxygen permeability is shown in FIG. FIG. 3 shows the relationship between the film thickness of the intermediate film and the ratio that was not removed by the adhesion test.

(Experiment 5)
An intermediate film was formed using methane gas as the first source gas at a gas flow rate of 120 sccm and a high frequency output of 600 W. The film formation time at this time was 3 seconds. The thickness of the intermediate film was 2.19 nm. Next, a DLC film was formed on the intermediate film under the same conditions as in Experiment 1. The total thickness of the film including the intermediate film was 21 nm. The oxygen transmission rate was 46.93 cc / m ² / day. According to the adhesion test, the percentage that did not peel was 58%. The relationship between the film thickness of the intermediate film and the oxygen permeability is shown in FIG. FIG. 3 shows the relationship between the film thickness of the intermediate film and the ratio that was not removed by the adhesion test.

(Experiment 6)
An intermediate film was formed using methane gas as the first source gas at a gas flow rate of 120 sccm and a high frequency output of 600 W. The film formation time at this time was 4 seconds. The film thickness of the intermediate film was 2.92 nm. Next, a DLC film was formed on the intermediate film under the same conditions as in Experiment 1. The total thickness of the film including the intermediate film was 22 nm. The oxygen transmission rate was 45.74 cc / m ² / day. According to the adhesion test, the percentage not peeled off was 61%. The relationship between the film thickness of the intermediate film and the oxygen permeability is shown in FIG. FIG. 3 shows the relationship between the film thickness of the intermediate film and the ratio that was not removed by the adhesion test.

(Comparative Example 1)
The oxygen permeability of the uncoated polylactic acid film was 100.38 cc / m ² / day. The results are shown in FIG.

(Reference Example 1)
The oxygen permeability of the uncoated PET film having a thickness of 200 μm was 13.34 cc / m ² / day. The results are shown in FIG.

(Comparative Example 2)
Without forming an intermediate film, a DLC film was directly formed on the polylactic acid film under the same conditions as in Experiment 1. The oxygen transmission rate was 82.78 cc / m ² / day. According to the adhesion test, the percentage that did not peel off was 0%. The relationship between the film thickness of the intermediate film and the oxygen permeability is shown in FIG.

  Referring to FIG. 3, it can be seen that by providing an intermediate film made of methane gas as a raw material, adhesion is greatly improved as compared with a case where a DLC film made of acetylene gas is directly formed on a polylactic acid film. It was. Further, referring to FIG. 2, even when the intermediate film is provided, the oxygen permeability is small in the range of 1.2 to 1.8 nm compared to the other film thickness ranges, It was found that the gas barrier property was even better.

(Experiment 7)
A DLC film was formed under the same conditions as in Experiment 1 except that methanol gas was used as the first source gas and the film formation time was 1.5 seconds. The oxygen transmission rate was 47.91 cc / m ² / day, and the rate at which it did not peel off by the adhesion test was 59%. It has been shown that a compound containing an element such as oxidation functions as an intermediate film like methane if the hydrocarbon portion does not contain a carbon double bond or carbon triple bond.

(Experiment 8)
An intermediate film was formed using a mixed gas of hexamethyldisiloxane (HMDSO) and oxygen 1: 1 as the first source gas at a gas flow rate of 120 sccm and a high frequency output of 600 W. The film formation time at this time was 2 seconds. The film thickness of the intermediate film containing SiO _x as a main component was 20 nm. Next, a DLC film was formed on the intermediate film under the same conditions as in Experiment 1. The total thickness of the film including the intermediate film was 42 nm. The oxygen transmission rate was 23.92 cc / m ² / day. According to the adhesion test, the percentage that did not peel off was 100%. Even when an intermediate film composed mainly of SiO _x was formed, it was confirmed that both the gas barrier property and the adhesiveness were high.

(Comparative Example 3)
An intermediate film containing SiO _x as a main component was formed under the same conditions as in Experiment 8. Furthermore, methane gas was used at a gas flow rate of 120 sccm, a high frequency output was 600 W, and a DLC film was formed. The total thickness of the film including the intermediate film was 21 nm. The oxygen transmission rate was 95.22 cc / m ² / day. The percentage that did not peel off by the adhesion test was 100%. In the case where a single layer of an intermediate film mainly composed of SiO _x was formed, there was adhesion, but gas barrier properties could not be obtained together with the DLC film using methane gas.

(Experiment 9)
A gas obtained by bubbling dimethylisopropylaluminum with nitrogen gas as a first raw material gas and a mixture of oxygen were used as a total of 120 sccm, and an intermediate film was formed at a high frequency output of 600 W. The film formation time at this time was 2 seconds. The thickness of the intermediate film containing AlO _x as a main component was 10 nm. Next, a DLC film was formed on the intermediate film under the same conditions as in Experiment 1. The total thickness of the film including the intermediate film was 42 nm. The oxygen transmission rate was 31.16 cc / m ² / day. According to the adhesion test, the percentage that did not peel off was 100%. Even when an intermediate film composed mainly of AlO _x was formed, it was confirmed that both gas barrier properties and adhesion were high.

(Comparative Example 4)
An intermediate film containing AlO _x as a main component was formed under the same conditions as in Experiment 9. Furthermore, methane gas was used at a gas flow rate of 120 sccm, a high frequency output was 600 W, and a DLC film was formed. The total thickness of the film including the intermediate film was 11 nm. The oxygen transmission rate was 96.33 cc / m ² / day. The percentage that did not peel off by the adhesion test was 100%. In the case where a single layer of an intermediate film mainly composed of AlO _x was formed, there was adhesion, but gas barrier properties could not be obtained together with the DLC film using methane gas.

  Film formation was performed on the inner surfaces of various plastic containers using the film formation apparatus shown in FIG. For example, as a plastic container, capacity 500 ml, container height 205 mm, container body diameter 65 mm, mouth opening inner diameter 21.74 mm, mouth opening outer diameter 24.94 mm, container body thickness 0.25 mm, resin An amount of 24.7 g / polylactic acid container was used. A PET container having the same shape as this was also used.

(Experiment 10)
An intermediate film was formed using methane gas as the first source gas at a gas flow rate of 120 sccm and a high frequency output of 600 W. The film formation time at this time was 2 seconds. The thickness of the intermediate film was 1.14 nm. Next, acetylene was used as the second source gas at a gas flow rate of 80 sccm. A DLC film was formed with a high frequency output of 1000 W. The film formation time at this time was 2 seconds. The total thickness of the film including the intermediate film was 20 nm. The oxygen permeability was 0.034 cc / container / day. According to the adhesion test, the percentage not peeled off was 72%. Both gas barrier properties and adhesion were good.

(Experiment 11)
Film formation was performed in the same manner as in Experiment 10 except that no intermediate film was formed. The thickness of the DLC film was 20 nm. The oxygen permeability was 0.047 cc / container / day. According to the adhesion test, the percentage that did not peel off was 3%. Compared with Experiment 9, the gas barrier property was slightly inferior, and adhesion was hardly obtained.

  The oxygen permeability of the uncoated polylactic acid container was 0.395 cc / container / day. The oxygen permeability of the uncoated PET container was 0.0499 cc / container / day. In the container of Experiment 10, the oxygen permeability was reduced to about 1/12 by forming an intermediate film before forming the DLC film, and the oxygen permeability was lower than that of the uncoated PET container. Was.

It is the schematic which shows one form of the film-forming apparatus which coats a DLC film on the inner wall surface of a plastic container. It is a graph which shows the relationship between the film thickness of an intermediate film, and oxygen permeability. It is a graph which shows the relationship between the film thickness of an intermediate film, and the ratio which did not peel in the adhesion test.

Explanation of symbols

1, lower external electrode 2, upper external electrode 3, external electrode 4, insulating part 5, lid part 6, vacuum chamber 7, container 8, O-ring 9, internal electrode 9a, gas outlet 12, matching box 13, high frequency power source 19, 25a, 25b, vacuum valve 20, exhaust pumps 16a, 16b, piping 17a, first source gas generation source 17b, second source gas generation source 18a, first source gas supply means 18b, second source gas supply means 40 ,space

Claims (8)

Using a raw material containing a compound in which carbon, silicon, or aluminum is a main constituent element and the constituent elements are bonded by a single bond, the surface of a container or film formed of a biodegradable plastic is formed by plasma CVD. A step of forming an intermediate film having a thickness of 0.5 to 20 nm and containing at least one of carbon, silicon, and aluminum as a main constituent element;
Using a raw material containing at least one of acetylene-based hydrocarbon, ethylene-based hydrocarbon, aromatic hydrocarbon, or silicon-containing hydrocarbon having a double bond or triple bond, a plasma CVD method is used to form the upper surface of the intermediate film. And a step of forming a DLC film or a silicon-containing DLC film. A method for producing a DLC film-coated biodegradable plastic container or film.   The method for producing a biodegradable plastic container or film according to claim 1, wherein polylactic acid is used as the biodegradable plastic.   Polylactic acid is used as the biodegradable plastic, methane gas is used as the raw material in the step of forming the intermediate film, and the film thickness of the intermediate film is 1.2 to 1.8 nm. A method for producing a DLC film-coated biodegradable plastic container or film according to claim 1. In the DLC film coating biodegradable plastic container or film in which the DLC film or the silicon-containing DLC film is formed on the surface of the container or film formed of the biodegradable plastic,
A DLC film-coated biodegradable plastic container or film, characterized in that the DLC film or the silicon-containing DLC film has adhesion strength at which peeling of the majority is not observed by a cross tape method of JISK5400 in Condition 1.
Condition 1: The gap between the cuts is 1 mm, and the number of squares is 100.   Carbon and hydrogen or carbon, silicon and hydrogen are mainly used at a thickness of 0.5 to 1.8 nm between the surface of the container or film made of the biodegradable plastic and the DLC film or the silicon-containing DLC film. 5. The DLC film-coated biodegradable plastic container or film according to claim 4, further comprising an intermediate film having various constituent elements.   Between the surface of the container or film formed of the biodegradable plastic and the DLC film or the silicon-containing DLC film, an intermediate film having a thickness of 0.5 to 20 nm and containing a metal oxide as a main component is provided. The DLC film-coated biodegradable plastic container or film according to claim 4, wherein 7. The DLC film coating raw material according to claim 6, wherein the metal oxide is SiO _x (where 1 ≦ x ≦ 2) or AlO _x (where 0.75 ≦ x ≦ 1.5). Degradable plastic container or film. The DLC film-coated biodegradable plastic container or film according to claim 4, wherein the biodegradable plastic is polylactic acid.

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