JP2006233234A - Vapor deposition film by plasma cvd method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vapor deposition film by a plasma CVD method having excellent adhesiveness to a base body and excellent resistance to water, in particular, alkaline aqueous solution. <P>SOLUTION: In the vapor deposition film deposited on a base body surface by the plasma CVD method using an organic metal compound and oxidizing gas as reaction gas, the vapor deposition film is demarcated into a base body side adhesive layer area with the carbon concentration of ≥ 5 element%, an intermediate layer barrier area with the carbon concentration < 5 element %, and a surface protective layer area with the carbon concentration of ≥ 5 element % under the three-element standard of the metal element (M), oxygen (O) and carbon (C) derived from the organic metal compound. On an outer surface of the surface protective layer area, the concentration of carbon (C) is higher than that of oxygen (O) and the metal element (M), the oxidation degree (x) of the metal element (M) is ≤ 1.3, the bond energy of the metal element (M) is smaller than the means value of the bond energy of the metal element in the intermediate layer barrier area by 1.0 eV, and in the intermediate layer barrier area, the oxidation degree (x) of the metal element (M) is > 1.8 and ≤ 2.4 on the average. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a deposited film formed on a surface of a substrate such as a plastic bottle by a plasma CVD method.

  Conventionally, in order to improve the characteristics of various substrates, a deposited film is formed on the surface by a plasma CVD method. For example, in the field of packaging materials, it is known to improve a gas barrier property by forming a deposited film on a plastic substrate such as a container by a plasma CVD method.

  For example, at least one or two or more of silicon oxide, carbon, hydrogen, silicon and oxygen are formed on at least one side of a plastic container by plasma CVD using at least an organic silicon compound and a gas having oxygen or oxidizing power. A method for producing a plastic container is known in which the concentration of the organosilicon compound changes when forming a barrier layer (deposited film) containing at least one compound composed of any of the above elements (see Patent Document 1). ).

And a base material, a gas barrier layer made of a deposited film formed on one or both sides of the base material, and a water repellent layer made of a water repellent film formed on the gas barrier layer. A characteristic gas barrier film is also known (see Patent Document 2).
JP 2000-255579 A (Claims) JP 2003-53873 A (Claims)

  However, the deposited film formed by the method of Patent Document 1, for example, has an excellent barrier effect against various gases such as oxygen, but has low durability against moisture. For example, silicon is added to an alkaline aqueous solution such as mineral water. In particular, in the field of packaging materials, there is a demand for improvement in addition to film adhesion to a substrate. In addition, the gas barrier film described in Patent Document 2 has a water-repellent layer formed on the surface of the gas barrier layer, which is a vapor-deposited film. In addition, the formation of the water-repellent layer cannot sufficiently suppress the elution of silicon into the alkaline aqueous solution.

  Accordingly, an object of the present invention is to provide a deposited film by a plasma CVD method that has not only good adhesion to a substrate but also excellent resistance to moisture, particularly an alkaline aqueous solution.

According to the present invention, in the deposited film formed on the substrate surface by the plasma CVD method using the organometallic compound and the oxidizing gas as the reaction gas,
On the basis of the three elements of metal element (M), oxygen (O) and carbon (C) derived from the organometallic compound, the deposited film has a substrate side adhesive layer region having a carbon concentration of 5 element% or more, a carbon concentration Is divided into an intermediate layer barrier region having less than 5 element% and a surface protective layer region having a carbon concentration of 5 element% or more,
On the outer surface of the surface protective layer region, the carbon (C) concentration is higher than the oxygen (O) concentration and the metal element (M) concentration, and the oxidation degree x of the metal element (M) (x is an element of the oxygen element with respect to the metal element) The bond energy of the metal element (M) is 1.0 eV or less smaller than the average value of the metal element bond energy in the intermediate barrier region,
In the intermediate layer barrier region, a deposited film is provided in which the oxidation degree x of the metal element (M) is higher than 1.8 and 2.4 or less on average.
According to the present invention, there is also provided a plastic bottle in which the deposited film is formed on the inner surface.

  In the present invention, the concentration of each element on the surface of the surface protective layer region, the oxidation degree x of the metal element (M), and the bond energy of the metal element (M) are determined from the surface depth by an X-ray photoelectron spectrometer. Means the measured value at 0.3 nm. The reason why the measured value on the surface is not used is to avoid the influence of contamination and the like.

In the deposited film of the present invention,
1. The organometallic compound is an organosilicon compound and the metal (M) is silicon (Si);
2. The substrate is plastic;
Is preferred.

  The vapor deposition film by the plasma CVD method of the present invention is formed by using an organometallic compound and an oxidizing gas as a reaction gas. This vapor deposition film is a region having a carbon concentration of 5 element% or more (substrate) Side adhesive layer region) is formed. That is, in this region, the carbon concentration is as high as 5 element% or more, and therefore the deposited film of the present invention has high adhesion to the substrate. Further, the intermediate region (intermediate layer barrier region) has a low carbon concentration of less than 5 element% and is mainly composed of an oxide of the metal element (M), and the oxidation degree x of the metal element (M) x Is in the range of higher than 1.8 and 2.4 or lower on average. For this reason, this area | region shows high gas-barrier property. Furthermore, in the surface side region (surface protective layer region), the carbon (C) concentration is the oxygen (O) concentration and the metal element on the surface (that is, the portion having a depth of 0.3 nm from the outer surface of the deposited film). (M) The concentration is higher than the concentration, the degree of oxidation x of the metal element (M) is 1.3 or less, and the bond energy of the metal element (M) is the average value of the metal element bond energy in the intermediate layer barrier region. The surface protective layer region is a region having a considerably higher degree of organicity than the intermediate barrier layer region. For this reason, the vapor-deposited film of the present invention exhibits excellent resistance to an alkaline aqueous solution, as will be apparent from the examples described later. For example, the metal element (M) does not elute in the alkaline aqueous solution. A plastic bottle having such a vapor deposition film on its inner surface can be put to practical use as a container for mineral water, alkaline ion beverages and the like.

  Please refer to FIG. 1 of the accompanying drawings. FIG. 1 schematically shows the elemental composition (M, O, C) of the deposited film of the present invention (especially prepared in the examples described later) measured by X-ray photoelectron spectroscopy. The deposited film is divided into three regions, that is, an outer surface protective layer region X, an intermediate layer barrier region Y, and an adhesive layer region Z from the outer surface side toward the substrate surface. That is, the deposited film of the present invention is formed on the surface of a predetermined substrate by a plasma CVD method using an organometallic compound and an oxidizing gas as a reaction gas. This deposited film is formed on the organometallic compound. The derived metal elements (M), oxygen (O), and carbon (C) are distributed as shown in FIG. 1, and are divided into the above three regions according to the element concentrations represented by these three element standards. The In FIG. 1, silicon (Si) is shown as the metal element (M).

  In FIG. 1, the adhesive layer region Z formed on the substrate surface side is a region having a (C) concentration of 5 element% or more, and this region is a highly organic and highly flexible region. That is, a metal oxide layer formed by plasma CVD (the intermediate layer barrier region described below corresponds to this) has a high inorganic property, a high oxygen barrier property, and a low flexibility. Adhesion may be lacking. However, the highly organic adhesive layer region has high flexibility and good adhesion to the substrate. Therefore, by forming the highly organic adhesive layer region Z on the surface of the substrate, it is possible to effectively avoid a decrease in adhesion and adhesion, and particularly high adhesion or adhesion to a plastic substrate. Indicates.

  In the adhesive layer region Z, it is preferable that the carbon concentration (C) gradually increases toward the substrate surface side, and on the interface side with the substrate surface, the carbon concentration (C) increases to 20 element% or more. It is particularly preferable to improve the adhesion to the substrate. As is clear from FIG. 1, when the carbon concentration (C) is gradually increased toward the interface with the substrate surface, the concentration of the metal element (M) and the oxygen (O) concentration are gradually increased accordingly. Decrease.

  In addition, the intermediate barrier layer region Y formed on the adhesive layer region has a (C) concentration of less than 5 element%. Therefore, in this region, the metal element (M), oxygen (O), The total concentration (M + O) is 95 element% or more. That is, this region Y formed in the central portion of the deposited film is a layer having a low organic property and rich in inorganic properties, and particularly has a high barrier property against oxygen. For example, when an organosilicon compound such as hexamethyldisiloxane (HMDSO) is used as the organometallic compound, the gas barrier layer region is mainly composed of silicon oxide. Therefore, the deposited film of the present invention is particularly useful in the field of packaging materials such as plastic containers that require barrier properties against gases such as oxygen and carbon dioxide.

Furthermore, in such a region Y, the oxidation degree x of the metal element (M) is as follows:
1.8 <x ≦ 2.4
Must be satisfied. The degree of oxidation x is expressed by the element ratio (MOx) of oxygen (O) to metal element (M), and exhibits high gas barrier properties when the degree of oxidation x is within the above range. When x is out of the above range, the gas barrier property is lowered.

  The surface protective layer region X located on the surface side of the deposited film is a region having a (C) concentration of 5 element% or more, and, like the adhesive layer region Z described above, has a large amount of carbon and is rich in organicity. In the present invention, the concentration of each element and the degree of oxidation x of the metal element (M) on the surface of the deposited film existing in the surface protective layer region X (specifically, at a depth of 0.3 nm from the outer surface). In addition, the binding energy of the metal element (M) needs to satisfy all of the following conditions (a) to (c).

Condition (a):
The carbon (C) concentration is higher than the oxygen (O) concentration and the metal element (M) concentration.
That is, C> O and C> M.
Condition (b):
The oxidation degree x of the metal element (M) is 1.3 or less.
Condition (c):
The bond energy of the metal element (M) is 1.0 eV or less smaller than the average value of the metal element bond energy in the intermediate layer barrier region Y.

  That is, the above conditions indicate that the surface of the deposited film is carbon-rich and extremely rich in organicity, and by satisfying all of these conditions, the water resistance of the deposited film is significantly improved. Elution of the metal element (M) into the aqueous alkaline solution can be effectively suppressed, and if any one of these conditions is not satisfied, the water resistance becomes unsatisfactory, and the metal element into the aqueous alkaline solution. Elution of (M) becomes remarkable. For example, as is clear from the experimental results of Example 1 and Comparative Example 1 described later, even if the conditions (a) and (c) are satisfied, the oxidation degree x of the metal element (M) on the surface is 1 When exceeding .49 and 1.3 (when the condition (b) is not satisfied), the amount of decrease in the film due to elution of the metal element (Si) when the deposited film is immersed in the alkaline aqueous solution for a certain time is 3 .4 nm (Comparative Example 1), when all of the conditions (a) to (c) are satisfied (Example 1), the amount of decrease in the film is 0.2 nm. It is understood that elution of (Si) is remarkably suppressed. The vapor deposition film of the present invention exhibits such excellent water resistance, probably because oxygen satisfying all of the above conditions (a) to (c) causes a decrease in water resistance on the vapor deposition film surface. This is probably because there are almost no atoms (O) or OH groups (silanol groups), and such oxygen atoms and OH groups are covered with a sufficiently thick surface protective layer.

  Moreover, in the vapor deposition film of the present invention, the above conditions (a) to (c) are satisfied on the vapor deposition film surface, and at the same time, as shown in FIG. As the carbon (C) concentration gradually increases, the concentration of metal elements (M) such as Si and the concentration of oxygen (O) gradually decrease. For example, the carbon (C) concentration is 40 element%. It is preferable to increase to the above, and it is particularly preferable that a region having a carbon (C) concentration of 40 element% or more exists with a thickness of 5 nm or more. By forming a region having a very high carbon (C) concentration on the surface side in this way, the intermediate layer barrier region Y is inferior in water resistance and easily causes elution of a metal element (M) such as silicon (Si). Can be covered with a sufficiently thick surface protective layer region X, water resistance can be remarkably improved, water penetration can be completely blocked, and deterioration of gas barrier properties due to moisture can be effectively avoided. .

  In the present invention, as understood from FIG. 1, the concentration of each element changes substantially continuously at the interface portion where the regions X, Y, and Z are adjacent to each other. That is, at these interface portions, the concentration of each element continuously decreases monotonously, which means that the regions X, Y, and Z are integrally formed, and are clearly defined between adjacent regions. This means that no interface is formed. Therefore, the vapor deposition film of the present invention does not cause separation between the respective regions, is extremely excellent in durability, and exhibits a stable barrier property over a long period against gases such as oxygen and moisture. .

  Thus, in the deposited film of the present invention, the surface protective layer region X, the intermediate layer barrier region Y, and the adhesive layer region Z are not present in the form of clear layers, and there is no clear interface between the layers. not exist. Therefore, although the thickness of each region cannot be critically defined, the thickness of the deposited film (total thickness of each region) is usually in the range of 4 to 500 nm, and the intermediate layer barrier region Y is approximately 4.0 nm. It is preferable to have the above thickness, and the adhesive layer region Z preferably has a thickness of approximately 0.2 nm or more.

  In the present invention, it is preferable to form the surface of the surface protective layer region X in a rough surface in order to improve the barrier property against moisture. For example, by adjusting the average surface roughness Ra (JIS B0601) to about 0.1 to 10.0 nm, the barrier property against moisture can be further enhanced. Such a rough surface can be formed, for example, by adjusting the degree of pressure reduction for glow discharge and forming glow discharge under a relatively high pressure when forming a deposited film.

[Substrate]
In the present invention, as the substrate on which the deposited film is to be formed, a substrate made of glass, various metals, or the like can be used, but a plastic substrate is most preferably used. Examples of such plastics include thermoplastic resins known per se, such as low density polyethylene, high density polyethylene, polypropylene, poly 1-butene, poly 4-methyl-1-pentene, ethylene, pyropyrene, 1-butene, 4- Polyolefins such as random or block copolymers of α-olefins such as methyl-1-pentene, cyclic olefin copolymers, ethylene / vinyl acetate copolymers, ethylene / vinyl alcohol copolymers, ethylene / vinyl chloride Copolymers and other ethylene / vinyl compound copolymers, polystyrene, acrylonitrile / styrene copolymers, ABS, styrene resins such as α-methylstyrene / styrene copolymers, polyvinyl chloride, polyvinylidene chloride, vinyl chloride / Vinylidene chloride copolymer, polyacrylic Polyvinyl compounds such as methyl phosphate and polymethyl methacrylate, polyamides such as nylon 6, nylon 6-6, nylon 6-10, nylon 11 and nylon 12, thermoplastic polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate , Polycarbonate, polyphenylene oxide and the like, biodegradable resins such as polylactic acid, or a mixture thereof.

  These substrates can be used in the form of films or sheets, and can be used in the form of containers such as bottles, cups, tubes, and other molded products. In particular, the bottle includes a biaxial stretch blow molded bottle formed from a polyester such as polyethylene terephthalate. Of course, the present invention can be applied to the polyester cup and biaxially stretched film as well.

  The plastic substrate may be a gas barrier multilayer structure having the above-described thermoplastic resin (preferably olefin resin) as an inner and outer layer and an oxygen-absorbing layer between these inner and outer layers. By forming the deposited film of the present invention on the inner layer and / or outer layer surface of such a multilayer structure, the oxygen barrier property can be remarkably improved.

[Reactive gas]
In the present invention, an organometallic compound and an oxidizing gas are used as a reaction gas. If necessary, a hydrocarbon serving as a carbon source can be used in combination with them.

In the present invention, an organosilicon compound is preferably used as the organometallic compound, but it is not limited to an organosilicon compound as long as it reacts with an oxidizing gas to form a metal oxide, For example, various things, such as organoaluminum compounds, such as a trialkylaluminum, others, an organic titanium compound, can be used. Examples of organosilicon compounds include hexamethyldisilane, vinyltrimethylsilane, methylsilane, dimethylsilane, trimethylsilane, diethylsilane, propylsilane, phenylsilane, methyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, tetramethoxysilane, Organic silane compounds such as tetraethoxysilane, phenyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, etc., organic such as octamethylcyclotetrasiloxane, 1,1,3,3-tetramethyldisiloxane, hexamethyldisiloxane A siloxane compound or the like is used. In addition to these materials, aminosilane, silazane, and the like can also be used.
The above-mentioned organic metals can be used alone or in combination of two or more. Moreover, silane (SiH ₄ ) or silicon tetrachloride can be used in combination with the above-described organosilicon compound.

Oxygen or NO _x is used as the oxidizing gas, and argon or helium is used as the carrier gas.

Further, as the carbon source, hydrocarbons such as CH ₄ , C ₂ H ₄ , C ₂ H ₆ , C ₃ H ₈ may be used in addition to the organosilicon compound and the organometallic compound.

[Formation of evaporated film]
In the present invention, a deposited film is formed on the surface of the substrate by the plasma CVD method in the atmosphere containing the reaction gas described above.

  Plasma CVD is a method for growing a thin film by using gas plasma. Basically, a gas containing a raw material gas is discharged under a reduced pressure with electric energy by a high electric field, decomposed and generated. It consists of a process in which a substance is deposited on a substrate in the gas phase or through a chemical reaction on the substrate. The plasma state is realized by glow discharge. Depending on the glow discharge method, a method using a direct current glow discharge, a method using a high frequency glow discharge, a method using a microwave discharge, and the like are known. .

Low temperature plasma CVD
a. Because it uses direct decomposition of gas molecules by fast electrons, it can easily dissociate raw material gas with large generation energy.
b. The electron temperature is different from the gas ion temperature, and the electron temperature is a high temperature that has the energy necessary to carry out a chemical reaction, but the ion temperature is in a thermal non-equilibrium state that is a low temperature, enabling a low temperature process.
c. A relatively uniform amorphous film can be formed even when the substrate temperature is low.
It can be easily applied to the formation of a deposited film on a plastic substrate.

  In the present invention, the deposited film must be formed so as to form the region shown in FIG. As such means, for example, there are means such as adjustment with a reactive gas or glow discharge output adjustment.

  When the reaction gas is used, for example, when the supply amount of the oxidizing gas is small as compared with the organometallic compound, the level of oxidative decomposition of the organometallic compound is low and a polymer is formed. As a result, regions having a large amount of carbon, such as the surface protective layer region X and the adhesive layer region Z, can be formed. Further, by increasing the supply amount of the oxidizing gas as compared with the organometallic compound, the oxidative decomposition of the organometallic compound proceeds to a high level, so that a nearly complete metal oxide is formed. As a result, a region with a small amount of carbon, that is, an intermediate layer barrier region Y can be formed. Furthermore, in order to form the surface protective layer region X, a hydrocarbon serving as a carbon source can be supplied.

  In addition, when each region X to Z is formed by adjusting the reaction gas, the balance between the output of the microwave and the supply amount of oxygen is considered so that the concentration of each element continuously changes and no interface is generated between the regions. Must.

  In addition, in the case of adjusting the output of glow discharge, for example, if a glow discharge generated by plasma is generated at a low output, regions such as the surface protective layer region X and the adhesive layer region Z with a large amount of carbon can be formed, When glow discharge is performed at high output, the intermediate layer barrier region Y with a small amount of carbon can be formed.

This output change method is based on the following principle.
For example, when an organic silicon oxide is taken as an example, it is considered that a silicon oxide film is formed by an organic silicon compound and an oxidizing gas through the following reaction path.
(a) Extraction of hydrogen: SiCH ₃ → SiCH ₂
(b) Oxidation: SiCH ₂ → SiOH
(c) Dehydration condensation: SiOH → SiO

That is, when glow discharge is performed at a high output, for example, an output of 100 W or more, the organosilicon compound reacts all the way to the stage (c). As a result, the intermediate layer barrier region Y with a high level of oxidative decomposition and a low carbon content. Is formed. On the other hand, when glow discharge is performed at a low output, for example, about 20 to 80 W, a reaction between SiCH ₂ radicals generated in the step (a) occurs, and an organosilicon compound polymer is generated. Many surface protective layer regions X and adhesive layer regions Z are formed.
In addition, when each region X to Z is formed by adjusting the output of glow discharge, the output adjustment of glow discharge is continuously changed so that the concentration of each element continuously changes and no interface is generated between the regions. It is necessary to make it.

  In the present invention, glow discharge for plasma generation is performed by a high-frequency electric field or a microwave electric field. When the substrate to be processed is plastic, when glow discharge is performed in a high-frequency electric field, the optimum conditions vary depending on the distance between the electrodes, etc., and cannot be specified unconditionally. However, glow discharge in the high output region has an output of 100 W or more. Preferably, when glow discharge is performed in a microwave electric field, the glow discharge at high output is preferably 90 W or more.

  In the present invention, a vapor deposition film surface satisfying the above-mentioned conditions (a) to (c) is formed, and the distribution of carbon (C) concentration and the like in the surface protective layer region X is as shown in FIG. In order to achieve this, for example, after forming the intermediate layer barrier region Y having a certain thickness, it is preferable to stop the supply of the reaction gas and start the glow discharge after replacing the atmosphere with the gas of the organometallic compound. When glow discharge is performed in the presence of a reactive gas, for example, the degree of oxidation x on the surface becomes higher than 1.3, and the water resistance of the deposited film may be reduced.

[Processing equipment]
In the present invention, the apparatus used for forming the vapor deposition film described above includes a plasma processing chamber including a substrate to be processed, an exhaust system for maintaining the plasma processing chamber in a reduced pressure state, and introducing a processing gas into the plasma processing chamber. A gas introduction system for processing and an electromagnetic wave introduction system for generating plasma in the plasma processing chamber. An example of such an apparatus is shown in FIG. 2 by taking a microwave plasma processing apparatus as an example.

  In FIG. 2, the plasma processing chamber denoted by 10 as a whole is composed of an annular base 12, a cylindrical side wall 14, and a canopy 16 that closes the upper portion of the cylindrical side wall 14.

  A first exhaust hole 20 is formed in the central portion of the annular base 12, and an annular recess 22 is formed on the upper surface of the base 12 so as to surround the first exhaust hole 20, Further, an annular groove 24 is formed around the annular recess 22, and the annular groove 24 communicates with the second exhaust hole 26.

  The annular recess 22 accommodates a bottle holder 30 that holds the bottle 28 in an inverted state. As is clear from FIG. 2, the bottle holder 30 is fitted with the neck portion of the bottle 28 in an inverted state, and the neck portion of the bottle 28 held by the holder communicates with the first exhaust hole 20. A gas supply pipe 32 is inserted into the bottle 28 from the one exhaust hole 20 through the neck of the bottle 28.

  The cylindrical side wall 14 is provided with a microwave introduction port 34, and a microwave transmission member 36 such as a waveguide or a coaxial cable is connected to the microwave introduction port 34. That is, a microwave is introduced into the plasma processing chamber 10 from a predetermined microwave oscillator through the microwave transmission member 36.

  The canopy 16 is provided with a cooling gas supply hole 40, whereby the cooling gas is held in an inverted state in the plasma processing chamber 10 after the deposition film is formed or during the deposition film formation. The bottle 28 is sprayed onto the bottom of the bottle 28 for cooling.

  Further, in order to ensure the hermeticity of the plasma processing chamber 10, O-rings 42 are respectively provided at the interface between the base 12 and the cylindrical side wall 14 and at the interface between the cylindrical side wall 14 and the canopy 16. . The bottle holder 30 is also provided with an O-ring 42 for blocking the inside and the outside of the bottle 28.

  Furthermore, a shield 44 for confining microwaves is provided in each of the first exhaust hole 20 and the second exhaust hole 26 formed in the base 12. Moreover, the base 12, the cylindrical side wall 14, and the canopy 16 are all made of metal for microwave confinement.

  In forming a deposited film by plasma treatment, first, the bottle holder 30 holding the bottle 28 in an inverted state is placed on the annular recess 22 of the base 12, and in this state, the base 12 is moved to an appropriate lifting device. And is bonded to the cylindrical side wall 14 to form a plasma processing chamber 10 in which a sealed and inverted bottle 28 is accommodated as shown in FIG.

  Next, the gas supply pipe 32 is inserted into the bottle 28 from the first exhaust hole 20, and the vacuum pump is driven to maintain the inside of the bottle 28 in a vacuum state by exhausting from the first exhaust hole 20. . At this time, in order to prevent the deformation of the bottle 28 due to the external pressure, the inside of the plasma processing chamber 10 outside the bottle 28 is decompressed from the second exhaust hole 26 by a vacuum pump.

  The degree of decompression in the bottle 28 is such that the degree of decompression is high such that glow gas is generated by introducing the processing gas from the gas supply pipe 32 and microwaves, and is particularly suitable, for example, 1 to 500 Pa. Is preferably in the range of 5-50 Pa. On the other hand, the degree of decompression in the plasma processing chamber 10 outside the bottle 28 is such that no glow discharge occurs even when microwaves are introduced.

  After reaching this reduced pressure state, a reactive gas is introduced into the bottle 28 through the gas supply pipe 32, and a microwave is introduced into the plasma processing chamber 10 through the microwave transmission member 36 to generate plasma by glow discharge. The electron temperature in this plasma is tens of thousands of K, the temperature of gas particles is about two orders of magnitude higher than that of several hundred K, and is in a thermally non-equilibrium state, compared to a low-temperature plastic substrate. However, plasma treatment can be performed effectively.

  The microwave output for the above reactive gas or glow discharge is adjusted as described above, and the deposited film is formed in order from the inner surface of the bottle, adhesive layer forming region Z, intermediate layer barrier region Y, and surface protection. When layer X is formed and its elemental composition is measured by X-ray photoelectron analysis, it is as shown in FIG. In the last stage, by increasing the pressure in the bottle 28 to about 15 to 500 Pa, the surface of the surface protective layer region X (that is, the surface of the deposited film) can be roughened and the barrier property against moisture can be improved.

  After performing the predetermined plasma processing, the introduction of the processing gas and the introduction of the microwave are stopped, the cooling gas is introduced from the cooling gas supply hole 40, the inside and outside of the bottle 28 are returned to normal pressure, and the plasma is supplied. By taking out the treated bottle 28 out of the plasma processing chamber 10, a plastic bottle on which a target vapor deposition film is formed can be obtained.

  The plasma treatment time differs depending on the inner surface area of the bottle to be treated, the thickness of the thin film to be formed, the kind of the processing gas, and the like. More than one second is necessary for the stability of the plasma treatment, and a reduction in time is required from the viewpoint of cost.

The present invention will be described in the following examples, but the present invention is not limited to the following examples in any way.

1. Composition analysis method in the film The inner surface of the body of the bottle coated with the vapor deposition film on the inner surface of each of the silicon, oxygen, and carbon in the depth direction of the film using an X-ray photoelectron spectrometer (Quantum2000) manufactured by PHI Distribution and silicon binding energy were measured.
The silicon concentration and oxygen concentration were corrected based on fused quartz (SiO ₂ ), and the film thickness was estimated at the same sputtering rate as that of fused quartz (SiO ₂ ) for convenience.

  In addition, each element concentration and silicon bond energy on the surface of the deposited film are shown as measured values at a position of an acceleration voltage of 2 kV, a sputtering range of 3 mm × 3 mm, and a depth of 0.3 nm from the film surface.

2. Evaluation of Alkali Resistance of Vapor Deposition Film 500 ml of an alkaline solution (commercial mineral water pH 7.3) is filled in a PET bottle coated with a vapor deposition film on the inner surface at room temperature, and the bottle mouth is sealed with a polypropylene cap. After storage for 28 days in an environment of 30% RH, measure the amount of silicon in the film over time with a fluorescent X-ray analyzer (Rigaku ZSX) and compare it with the amount of silicon in the pre-timed bottle made under the same conditions Then, the alkali resistance of the deposited film was evaluated by the decrease amount of the silicon amount. For each bottle, the average value of silicon amounts measured at six points in the height direction was taken as the film thickness.

Example 1
A microwave power source with a frequency of 2.45 GHz and a maximum output of 1.2 kW, a metal cylindrical plasma processing chamber with a diameter of 90 mm and a height of 500 mm, an oil rotary vacuum pump that evacuates the processing chamber, and a microwave from the oscillator to the plasma processing chamber The apparatus shown in FIG. 2 having a rectangular waveguide to be introduced in FIG.

  The gas supply pipe uses a sintered stainless steel gas supply pipe having a porous structure with an outer diameter of 15 mm and a length of 150 mm. The bottle holder is a cylindrical polyethylene having a diameter of 28 mm, a barrel diameter of 64 mm, a height of 206 mm, and an internal volume of 520 ml. A terephthalate bottle (PET bottle) was installed, the vacuum inside the processing chamber was 7 kPa, the vacuum inside the bottle was 10 Pa, 2.7 sccm of hexamethyldisiloxane (hereinafter referred to as HMDSO), and 27 sccm of oxygen were introduced. Thereafter, a pulsed microwave of 500 W was oscillated from a microwave oscillator to perform plasma treatment. At that time, a deposition film composed of the adhesive layer region Z and the intermediate layer barrier region Y was formed by changing the oscillation time of the microwave. Thereafter, the supply of oxygen gas was stopped and the inside of the bottle was replaced with an HMDSO atmosphere, and then the surface protective layer region was formed. The deposition time for each region was 3 sec (region Z), 5 sec (region Y), and 3 sec (region X).

After the surface protective layer region X was formed, the atmosphere was released to complete the deposition film deposition.
FIG. 1 shows the composition distribution in the depth direction of the silicon, oxygen, and carbon films and the binding energy of Si by the composition analysis method in the film at this time. Moreover, each element density | concentration in the vapor deposition film surface, oxidation degree x, the bond energy of silicon, the average silicon bond energy in the intermediate | middle layer barrier area | region Y, and the average oxidation degree x are together with the result of alkali resistance evaluation (film reduction amount), It is shown in Table 1.

(Comparative Example 1)
Plasma treatment was performed in the same manner as in Example 1 to form a deposited film composed of the adhesive layer region Z and the intermediate layer barrier region Y. Thereafter, the supply of oxygen gas was stopped, and the surface protective layer region X was immediately processed for 0.5 sec.

After the surface protective layer region was formed, the atmosphere was released to complete the deposition film deposition.
The composition distribution in the depth direction of the silicon, oxygen, and carbon films and the bond energy of silicon by the composition analysis method in the film at this time are shown in FIG. 3, and further, the concentration of each element on the surface of the deposited film and the alkali resistance evaluation The results are shown in Table 1.

(Comparative Example 2)
A vapor deposition film was formed in the same manner as in Example 1 except that the supply amount of oxygen at the time of forming the surface protective layer region was set to 2.7 sccm, and the same analysis and evaluation as in Example 1 were performed. The results are shown in Table 1.

(Comparative Example 2)
Except that the surface protective layer region X was not formed, a deposited film was formed in the same manner as in Example 1, and the same analysis and evaluation as in Example 1 were performed. The results are shown in Table 1.

  From the above results, it can be seen that the deposited films of the examples satisfying all of the conditions (a) to (c) described above show good alkali resistance.

  Moreover, the relationship between the concentration ratio of the outer surface of the bottle produced on various conditions and a film | membrane reduction | decrease is shown to FIGS. From these results, when the concentration of each element on the outer surface satisfies C> O, C> Si, and the degree of oxidation x is 1.3 or less, it shows a good surface protection effect and shows good alkali resistance. It was confirmed.

The figure which shows the elemental composition in the thickness direction of the vapor deposition film of this invention obtained in Example 1, and the bond energy of silicon. The figure which shows the structure of the plasma processing apparatus for forming the vapor deposition film of this invention. The figure which showed the element concentration in the thickness direction of the vapor deposition film of the comparative example 1, and the bond energy of silicon. The figure which showed the relationship between C / O ratio of the surface, and film thickness reduction amount. The figure which showed the relationship between C / Si ratio of a surface, and film thickness reduction amount. The figure which showed the relationship between O / Si ratio (oxidation degree) of a surface, and film thickness reduction amount.

Claims (4)

In the deposited film formed on the substrate surface by the plasma CVD method using the organometallic compound and the oxidizing gas as the reaction gas,
On the basis of the three elements of metal element (M), oxygen (O) and carbon (C) derived from the organometallic compound, the deposited film has a substrate side adhesive layer region having a carbon concentration of 5 element% or more, a carbon concentration Is divided into an intermediate layer barrier region having less than 5 element% and a surface protective layer region having a carbon concentration of 5 element% or more,
The surface protective layer region has a carbon (C) concentration higher than an oxygen (O) concentration and a metal element (M) concentration, and an oxidation degree x (x) of the metal element (M) on the surface of the surface protective layer region. Is expressed by an element ratio of an oxygen element to a metal element) is 1.3 or less, and the bond energy of the metal element (M) is higher than the average value of the metal element bond energy in the intermediate layer barrier region by 1. Smaller than 0eV,
In the intermediate layer barrier region, the deposited film is characterized in that the average oxidation degree x of the metal element (M) is higher than 1.8 and not higher than 2.4.   The deposited film according to claim 1, wherein the organometallic compound is an organosilicon compound, and the metal (M) is silicon (Si).   The vapor deposition film according to claim 1, wherein the substrate is plastic. 4. A plastic bottle, wherein the vapor deposition film according to claim 1 is formed on an inner surface.

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