JP2009166329A - Gas-barrier film, packaging bag, and manufacturing method of gas-barrier film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas-barrier film having thermally melt-sticking property, a little residue of combustion wastes, a small environmental load, and excellent transparency, by improving oxygen barrier of a polyolefin film having thermally melt-sticking property such as polyethylene or polypropelene. <P>SOLUTION: In the gas-barrier film 1, there is formed a gas-barrier layer of a silicon oxide thin film 3 containing carbon by plasma CVD on at least one side of a substrate 2 composed of thermally melt-sticking polyolefin, with a protective layer 4 provided on the silicon oxide thin film 3, wherein the protective layer 4 is made up of a coating layer of a resin composition having no gas-barrier property. The resin composition is desirably one that substantially contains no vinylidene chloride type copolymer, ethylene-vinyl alcohol copolymer, and polyvinyl alcohol. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a gas barrier film, and more specifically, has a heat-fusible property (sometimes referred to as heat-sealability), has a small residue of combustion waste, and has a small environmental load. The present invention relates to a gas barrier film excellent in transparency, a packaging bag using the film, and a method for producing the gas barrier film.

Conventionally, gas barrier films have been used for packaging foods, pharmaceuticals, chemicals, medical instruments, electronic parts, etc., to prevent the permeation of water vapor and oxygen and maintain a constant internal atmosphere.
As the gas barrier film, those by the following methods (1) to (3) are widely used.
(1) A substrate film laminated with a metal foil such as aluminum.
(2) A deposited film obtained by forming a thin film of metal or metal oxide on a base film by vacuum deposition or sputtering.
(3) A gas barrier resin obtained by coating a base film with a resin composition having a gas barrier property such as a vinylidene chloride copolymer, an ethylene-vinyl alcohol copolymer, or polyvinyl alcohol.

However, these conventional gas barrier films have the following drawbacks.
The metal foil of (1) has an excellent barrier property against water vapor and oxygen, but there is a problem that incineration of waste after use increases the incineration residue and places a burden on the environment. In addition, there is a problem in use that the contents are not transparent and the contents cannot be visually confirmed.

The method using the vapor deposition film of (2) has a problem that it cannot be easily implemented because a large-scale vapor deposition apparatus is required for the production facility. In addition, the metal oxide vapor deposition film as the gas barrier layer lacks flexibility, and there is a problem that the gas barrier property is deteriorated due to stagnation and bending.

(3) Due to the gas barrier resin, the vinylidene chloride copolymer has an environmental problem in waste treatment that chlorine is generated when it is burned. Regarding the ethylene-vinyl alcohol copolymer and polyvinyl alcohol, There is a problem that the oxygen barrier property is remarkably lowered under high humidity or high temperature.

In order to eliminate these various drawbacks, a transparent metal oxide thin film is formed on a base film using a method such as vacuum deposition, sputtering, or plasma CVD without using a metal foil. (Patent Documents 1 to 6).
On the other hand, the gas barrier properties of polyethylene, polypropylene, and polyethylene terephthalate, which are representative synthetic resins used as packaging materials, are as shown in Table 1 (extracted from Non-Patent Document 1).

According to Table 1 above, polyethylene and polypropylene are not inferior in water vapor transmission rate but very high oxygen transmission rate compared to polyethylene terephthalate.
For this reason, in the production of a gas barrier film imparted with a gas barrier property, polyethylene and polypropylene, which are general-purpose resins, are not used for the base film, but the gas barrier property is basically excellent, and the polyethylene has both a low water vapor transmission rate and a low oxygen transmission rate. In general, a vapor-deposited film of a transparent metal oxide is formed on a base film using terephthalate (PET) as a base film (see Examples in Patent Documents 1 to 4).
Japanese Patent Publication No. 51-48511 JP 62-103139 A JP-A-7-304127 Japanese Patent Laid-Open No. 7-80986 JP-A-10-329286 JP-A-11-105188 Toshiyuki Sugao, Kazuyuki Horie and Shusaku Shiraishi, “Polymer Material (Material Technology 16)”, University of Tokyo Press, 1984, p. 110-111

  However, a gas barrier film in which a transparent metal oxide vapor-deposited film is formed on a base film using polyethylene terephthalate (PET) as the base film has a base film having heat-fusibility. Therefore, when used as a material for packaging bags, a polyolefin resin film having heat fusion properties such as polyethylene and polypropylene is laminated via an adhesive, or a polyolefin resin having these heat fusion properties is used. It was necessary to laminate by extrusion lamination.

For example, in Patent Document 1, Example 2 discloses that silicon monoxide is vacuum-deposited on one surface of a polyester film, and low-density polyethylene is extruded and laminated on the vapor-deposited surface.
Moreover, in patent document 2, the packaging material which vacuum-deposited silicon monoxide on the single side | surface of the polyester film in Example 1 and laminated | stacked the polypropylene film on the vapor deposition side via the polyurethane adhesive was obtained, and a polypropylene film was obtained. It is disclosed that a retort pouch is produced by heat sealing inside.

It is also known to form a silicon oxide thin film using plasma CVD. For example, Patent Document 3 discloses a gas barrier packaging material in which a silicon oxide thin film is formed on at least one surface of a plastic substrate. Has been.
In the example of Patent Document 3, a high-frequency plasma CVD is used, a material gas is hexamethyldisiloxane and oxygen gas, an inert gas, a biaxially stretched polyethylene terephthalate (PET) film is used as a base material, and a silicon oxide thin film is used. Is forming.

  Patent Document 4 discloses that at least one surface of a base film layer, which has a high gas barrier property at a high temperature, has a gas barrier resin coating layer (silicon oxide) through a transparent inorganic layer (silicon oxide). A gas barrier film coated with a vinylidene chloride copolymer or ethylene-vinyl alcohol copolymer) is disclosed, but in the examples, polyethylene terephthalate (PET) is used.

  As described above, in the prior art, when a metal oxide thin film is formed on a base film by vapor deposition or plasma CVD, the base film is made of polyethylene having both water vapor permeability and oxygen permeability. A terephthalate (PET) film is generally used, and general-purpose resins such as polyethylene and polypropylene have not been used for a base film.

  Slightly, Patent Documents 5 and 6 disclose a technique for forming a metal oxide vapor-deposited film on polypropylene as a base film, but a special polypropylene film is used, and general-purpose heat fusion is performed. It does not relate to a polypropylene film having properties.

  For example, in patent document 5, the very special polypropylene film which is not generally marketed is used. Patent Document 5 is a polypropylene composite film in which a gas barrier layer made of a metal vapor deposition film or a metal oxide vapor deposition film is formed on a polypropylene film substrate having a syndiotactic polypropylene layer, and a protective layer is formed on the gas barrier layer. .

The protective layer comprises a water-soluble polymer that is at least one selected from the group consisting of polyvinyl alcohol, polyvinyl pyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, and sodium alginate, a group consisting of metal alkoxide, a hydrolyzate thereof, and tin chloride. The film is formed by applying and drying an aqueous paint containing at least one selected from the group consisting of:
Moreover, the protective layer formed on this gas barrier layer is laminated | stacked in order to improve the gas barrier property of a polypropylene composite film material more, and is not a mere protective layer.

In Patent Document 6, at least two kinds of inorganic oxides are provided on one surface of a biaxially oriented polypropylene film substrate, and the first thin film is an inorganic oxide vapor deposition film formed by physical vapor deposition. There is disclosed a transparent barrier polypropylene film in which the second thin film is a deposited film of an inorganic oxide by a plasma chemical vapor deposition method.
However, in this case, since the biaxially stretched polypropylene film is used as the base film, the heat-fusible property is lacking, and a polyolefin-based resin layer having heat-fusible properties is separately laminated via the adhesive layer. There was a need.

  For this reason, it is a gas barrier film that cannot be provided by the prior art, and a gas barrier layer having transparency is directly formed on a polyolefin film having heat fusion properties such as polyethylene and polypropylene, which are general-purpose resins, and incineration residue. Therefore, there is a demand for a gas barrier film having a small amount and a low environmental load and excellent transparency.

  The present invention has been made in view of the above circumstances, and has heat-fusibility by improving the oxygen barrier properties of polyolefin films having heat-fusibility, such as polyethylene and polypropylene, which are general-purpose resins. It is an object of the present invention to provide a gas barrier film having a small amount of combustion waste residue and a low environmental load, and having excellent transparency, a packaging bag using the film, and a method for producing the gas barrier film.

In order to solve the above problems, the present invention provides a silicon oxide thin film gas barrier layer containing carbon formed by plasma CVD on at least one surface of a base material made of polyolefin having heat-fusibility, and the silicon oxide Provided is a gas barrier film characterized by having a protective layer comprising a coating layer of a resin composition having substantially no gas barrier property on a thin film.
Moreover, it is preferable that the said resin composition is a resin composition which does not contain a vinylidene chloride copolymer, an ethylene- vinyl alcohol copolymer, and polyvinyl alcohol substantially.
Moreover, it is preferable that the said resin composition is water-insoluble.

Moreover, this invention provides the packaging bag characterized by the packaging material which comprises a packaging bag comprising said gas barrier film as at least one part.
Further, the present invention provides a plasma reaction between an organometallic silicon and oxygen in an inert gas, in a vacuum glow discharge or an atmospheric pressure glow discharge, on at least one surface of a base material made of polyolefin having heat-fusibility. Forming a gas barrier layer of a silicon oxide thin film containing carbon produced by forming a protective layer composed of a coating layer of a resin composition having substantially no gas barrier property on the silicon oxide thin film. A method for producing a gas barrier film is provided.

  According to the present invention, it is possible to provide a gas barrier film that has heat-fusibility, has little residue of incineration waste, has a low environmental load, and is excellent in transparency, and a method for producing the same.

  In addition, according to the present invention, since a heat-sealable polyolefin film is used for the base film, there is no need to laminate a heat-sealable polyolefin film again in order to impart heat sealability. It is convenient to use the gas barrier film of the present invention as a packaging material, and it becomes possible to reduce the number of manufacturing steps and manufacturing cost of the packaging bag.

The present invention will be described below with reference to the drawings based on the best mode.
FIG. 1 is a schematic cross-sectional view showing a gas barrier film of the present invention. FIG. 2 is a scanning electron micrograph of the gas barrier film shown in Example 1 of the present invention, in which the surface of a film in which a protective layer is formed on a silicon oxide thin film by plasma CVD is observed. FIG. 3 is a scanning electron micrograph observing the surface of a film which is only a silicon oxide thin film by plasma CVD and has no protective layer shown in Comparative Example 3 of the present invention.

First, the structure of the gas barrier film of the present invention will be described with reference to FIG.
In the gas barrier film 1 of the present invention, a gas barrier layer of a silicon oxide thin film 3 is formed on a base material 2 made of polyolefin having heat-fusibility, and substantially has gas barrier properties on the silicon oxide thin film. A protective layer 4 made of a coating layer of the resin composition not formed is formed.

The gas barrier layer is made of a silicon oxide thin film containing carbon formed by plasma CVD. The protective layer comprising the coating layer of the resin composition having substantially no gas barrier property is a resin composition substantially free of vinylidene chloride copolymer, ethylene-vinyl alcohol copolymer, and polyvinyl alcohol. It is preferable that the product is coated.
Moreover, it is preferable that the said resin composition is water-insoluble.

As a form of said base material 2, a sheet form or a film form is mentioned. Specific examples of the polyolefin having the heat-fusibility of the base material 2 include low density polyethylene (LDPE), high density polyethylene (HDPE), linear low density polyethylene (LLDPE), polypropylene, polybutylene, and ethylene. -A propylene copolymer etc., Comprising: If it is resin which can be used as a normal packaging material, there will be no restriction | limiting in particular. As the polypropylene, a commonly used isotactic polypropylene is preferable.
In the present invention, whether or not a polyolefin has heat-fusibility is determined so long as at least the same material can be heat-fused. In addition, if another material that can be used in accordance with the purpose and the polyolefin can be heat-sealed, the polyolefin has a heat-sealing property to the other material.

Although there is no restriction | limiting in particular in the shape of the base material 2, It is preferable that it is a roll-shaped long film.
Although there is no restriction | limiting in particular in the thickness of the film of the base material 2, Generally, it is convenient on handling to set it as the thickness of 5 micrometers-200 micrometers, More preferably, it is about 10 micrometers-100 micrometers. If the thickness of the substrate film is less than 5 μm, it tends to be wrinkled, and if it is thicker than 200 μm, it is difficult to wind it on a roll body.

The base material 2 made of polyolefin having heat-fusibility according to the present invention is preferably an unstretched (sometimes referred to as non-stretched) resin film having excellent heat-fusibility. This is because the resin film that has been uniaxially or biaxially stretched has reduced heat-sealing properties, particularly heat-sealing strength.
The base film is produced by a conventional molding method. As a method for molding a resin film, for example, a melt extrusion molding method such as an inflation method or a T-die method, or a step of pouring and adhering a molten resin onto a drum or a stainless steel smooth belt having a smooth surface and heating the same And a solution casting method in which the solvent is evaporated to form a film. In the case of polyolefin, a base film is produced mainly by a melt extrusion molding method.

  Further, the film of the base material 2 may be added with a known antistatic agent, lubricant, ultraviolet absorber, colorant or the like, or may be treated with a corona treatment to increase the adhesion between the base material and the gas barrier layer. A known surface treatment such as atmospheric pressure plasma treatment may be applied.

In the present invention, the silicon oxide thin film functioning as a gas barrier layer is formed by plasma CVD. Carbon produced by plasma reaction of organometallic silicon and oxygen in an inert gas in a vacuum glow discharge or atmospheric pressure glow discharge is applied to at least one surface of a base material made of polyolefin having heat-fusibility. A gas barrier layer of the silicon oxide thin film is formed.
A so-called atmospheric pressure plasma reactor that performs plasma reaction by atmospheric pressure glow discharge is operated under atmospheric pressure and does not require a vacuum evacuation facility, so that it is relatively easy to handle.
For this reason, as an apparatus for forming a silicon oxide thin film, a plasma reactor using atmospheric pressure glow discharge is more preferably used than a plasma reactor using vacuum glow discharge.

In the present invention, as the organometallic silicon, one or more of silicon compounds used as a raw material for forming a silicon oxide thin film in plasma CVD can be used without particular limitation. From the viewpoint of stability at room temperature and the like, it is preferable to use silicon alkoxide or organosiloxane that is liquid at room temperature.
More specifically, the silicon alkoxide includes tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), vinyltriethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, Ethylmethoxysilane, ethyltrimethoxysilane, etc. can be used.
Further, as the organic siloxane, hexamethyldisiloxane (HMDSO), 1,1,3,3-tetramethyldisiloxane (TMDSO), octamethyltetrasiloxane, divinylhexamethyltrisiloxane, divinyltetramethyldisiloxane, trivinyl Pentamethyltrisiloxane can be used.

  The organometallic silicon that is liquid at room temperature is usually introduced into a plasma reactor using glow discharge using an inert gas such as nitrogen gas, helium gas, or argon gas as a carrier gas. In addition, oxygen gas barrier property is improved by adding an appropriate amount of oxygen gas to organometallic silicon, for example, tetramethoxysilane (TMOS), and causing a plasma reaction. However, if oxygen is added excessively, discharge becomes unstable. The deposited film becomes non-uniform.

The gas barrier layer according to the present invention uses, for example, tetramethoxysilane (TMOS) as organometallic silicon, and is reacted with oxygen gas and inert gas on the surface of the substrate in a plasma reactor using atmospheric pressure glow discharge. The silicon oxide thin film containing carbon was produced | generated on the surface of this. As a result of analyzing the composition of the silicon oxide thin film deposited on the surface of the substrate by using an X-ray photoelectron spectrometer (XPS), the deposit was not pure silicon dioxide (SiO ₂ ), but a little carbon component was obtained. It was found to be a thin film of silicon oxide (see Table 2). For this reason, in the present invention, it is called a gas barrier layer made of a silicon oxide thin film containing carbon.

  The thickness of the gas barrier layer comprising the silicon oxide thin film containing carbon of the present invention is usually preferably 30 to 500 nm, more preferably about 50 to 400 nm. If the thickness of the gas barrier layer is 30 nm or less, the gas barrier property is inferior, and if the thickness is 500 nm or more, there is an inconvenience that the gas barrier layer becomes opaque and cracks easily occur.

In this invention, the protective layer which consists of a coating layer of the resin composition which does not have gas barrier property substantially is formed on the silicon oxide thin film which functions as a gas barrier layer.
The resin composition used for forming this protective layer (hereinafter referred to as a protective layer-forming resin composition) is a resin substantially free of vinylidene chloride copolymer, ethylene-vinyl alcohol copolymer, and polyvinyl alcohol. It is a composition and is not laminated to increase gas barrier properties. That is, in the present invention, a coating layer having substantially no gas barrier property is coated by coating a vinylidene chloride copolymer, an ethylene-vinyl alcohol copolymer, and a resin composition substantially free of polyvinyl alcohol. A protective layer made of is formed.

The role of the protective layer merely has a function as a buffer layer that relieves external stress so that the silicon oxide thin film does not crack. Here, as the protective layer does not substantially have a gas barrier property, gas permeability of the laminate provided with only protective layer on the substrate layer (hereinafter referred to as T ₁₎ is a gas permeability of the substrate layer itself (hereinafter referred to as _{T 0)} is what is preferably at least 80% of the. More preferably, T ₁ is 90% or more of T ₀ , and more preferably, T ₁ is 95% or more of T ₀ .

In addition, since the silicon oxide thin film functioning as a gas barrier layer is very fragile to moisture, the resin composition of the protective layer coated on the silicon oxide thin film should not contain moisture as much as possible. Is preferred.
When a protective layer is formed using polyvinyl alcohol, which is a water-based resin composition, on the resin composition of the protective layer that is coated on the silicon oxide thin film, the silicon oxide thin film is cracked and oxygen permeable The rate could not be measured.

For this reason, it is preferable that the resin composition for forming a protective layer is water-insoluble because the silicon oxide thin film is vulnerable to moisture.
In order to form a protective layer consisting of a coating layer of a resin composition having substantially no gas barrier property of the present invention, it is a resin solution dissolved in an organic solvent and does not contain moisture or has a moisture content of Use less resin solution.
As the resin used for the resin solution, a resin having solubility in an organic solvent can be used. Examples of such resins include polyester resins, isocyanate resins, urethane resins, (meth) acrylic resins, ethylene- (meth) acrylic copolymer resins, epoxy resins, modified styrene resins, and modified silicon resins. The resins can be used alone or in combination of two or more.
In this, acrylic resin is used suitably from the point which has a high glass transition temperature of about 100 degreeC.

  Examples of organic solvents include hydrocarbons (toluene, n-heptane, etc.), halogenated hydrocarbons (methylene chloride, chloroform, etc.), ketones (methyl ethyl ketone, methyl isobutyl ketone, etc.), esters (ethyl acetate, butyl acetate, etc.) ) And the like, and these organic solvents can be used alone or in combination of two or more.

  In the present invention, the method of coating the protective layer-forming resin composition on the silicon oxide thin film includes gravure coating, roll coating, reverse coating, spin coating, spray coating, and the like, but is not limited thereto. Is not to be done.

Although the thickness of the coating layer of the resin composition for forming a protective layer is appropriately selected within a range that does not impair flexibility as a gas barrier film, it is usually 0.5 to 50 μm, more preferably about 1 to 30 μm. . When the thickness is 0.5 μm or less, the function as a buffer layer for relaxing external stress cannot be sufficiently exhibited. On the other hand, if the thickness is 50 μm or more, there is an inconvenience that flexibility is lowered.
In order to protect the silicon oxide thin film produced by plasma CVD, it is preferable to coat the resin composition for forming a protective layer as soon as possible after the formation of the silicon oxide thin film. When a gas barrier film is produced by roll-to-roll using a long base film, after the base film is unwound from the roll, formation of a silicon oxide thin film, coating of a resin composition for forming a protective layer, and drying Thus, it is desirable to perform winding after the protective layer is completed.

On the protective layer, if necessary, a printed layer on which characters or designs are printed may be laminated, and a surface coating film may be bonded thereto via an adhesive.
The printed layer is used to display characters and designs required for packaging bags, etc., and includes additives such as various pigments, desiccants, stabilizers, etc. for urethane and acrylic ink binder resins. Is a layer formed by applying the added ink.
The printing layer is formed by a known printing method such as an offset printing method, a gravure printing method, or a screen printing method. The thickness of the printing layer is usually about 0.05 to 2.0 μm.

  In the packaging bag of the present invention, the packaging material constituting the packaging bag comprises the gas barrier film of the present invention as at least a part. The packaging bag of the present invention may be composed only of the gas barrier film of the present invention, or may be composed of a film formed by laminating two or more layers of the gas barrier film of the present invention. It may be composed of a film formed by laminating with another resin film, or may be composed of a packaging material formed by combining the gas barrier film of the present invention with a substrate other than the film. Since the gas barrier film of the present invention has a base material made of polyolefin having heat-fusibility, a packaging bag can be produced by heat-sealing even if the film is used alone. Moreover, the packaging bag which can see through the content can be obtained, without using the packaging material with which metal foil was compounded.

EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to a following example, unless the summary is exceeded.
In addition, the measurement of each physical property in an Example was performed based on the following measuring methods.

(Measurement method of oxygen permeability)
According to JIS K 7126, it measured on 30 degreeC and 70% RH conditions using the oxygen-permeation rate measuring apparatus (The product made by Mocon, model OX-TRAN 2/20).
(Composition analysis of deposits on the substrate surface)
Composition analysis was performed using an X-ray photoelectron spectrometer (XPS) (type ULCA made by ULVAC-PHI Co., Ltd., model ESCA-5800ci).
(Observation of film surface condition)
Using a scanning electron microscope (SEM) (manufactured by JEOL Ltd., model JPS-6100), the surface state of the silicon oxide thin film as the gas barrier layer and the resin coating layer as the protective layer was observed.

(Analysis of reaction products by plasma CVD)
Using tetramethoxysilane (TMOS) as organometallic silicon, oxygen gas and inert gas were reacted on the surface of the substrate in a plasma reactor using atmospheric pressure glow discharge, and formed on the surface of the substrate and the surface of the substrate. The composition of the deposit was analyzed by XPS.
As shown in Table 2 above, the XPS analysis results revealed that the deposits contained a small amount of carbon components but were almost silicon oxide thin films. Since the substrate is a polyolefin film (consisting only of carbon and hydrogen), only carbon is detected by XPS.

(Plasma reaction conditions)
A silicon oxide thin film was deposited on the base film using a plasma reactor using atmospheric pressure glow discharge. By adding oxygen gas to tetramethoxysilane (TMOS) and causing a plasma reaction, the oxygen gas barrier property is improved. However, if oxygen is added excessively, the discharge becomes unstable and the deposited film becomes non-uniform.
As conditions for stable discharge, the TMOS flow rate of 1.6 mg / min and the oxygen gas flow rate of 1 cm ³ / min were found to be the best, and the plasma reaction conditions in the following examples were used.

Example 1
An unstretched high-density polyethylene (HDPE) film having a thickness of 100 μm (brand name HD, manufactured by Tamapoly Co., Ltd.) is treated under the following plasma reaction conditions by atmospheric pressure glow discharge, and a silicon oxide containing carbon having a thickness of 400 nm A thin film was formed.

(Plasma reaction conditions by atmospheric pressure glow discharge)
Power frequency 13.56MHz
Pulse modulation mode ON
Pulse frequency 10 kHz [Conditions applied when pulse modulation mode is ON]
Duty ratio 20%
He flow rate 4000 cm ³ / min
TMOS flow rate 0.7-7.2mg / min
O ₂ flow rate 1-7 cm ³ / min
Discharge time 60min
Distance between electrodes 2mm
Discharge output 100W
Deposited film thickness 400-500nm

  Next, an acrylic resin paint (manufactured by Nippon Shokubai Co., Ltd., Polyment NK-380 (Tg = 100 ° C.)) is used as a protective layer-forming resin composition on the silicon oxide thin film formed on one side of the substrate. A coating solution diluted with a solvent (toluene / methyl isobutyl ketone = 3/1) in a range of 10 to 100% was prepared and dried at a drying temperature of 40 ° C. for 5 seconds to form a protective layer having a thickness of 5 μm. This was designated as Example 1.

(Example 2)
In Example 1, the other treatment conditions were the same, and the thickness of the protective layer was 20 μm, which was designated as Example 2.

(Comparative Example 1)
An unstretched high-density polyethylene (HDPE) film (made by Tamapoly Co., Ltd., brand HD) having a thickness of 100 μm is used as a base material made of polyolefin having heat-fusibility, and the base material is not provided with a silicon oxide thin film and a protective layer. This was used as Comparative Example 1.

(Comparative Example 2)
On the base material of Comparative Example 1, an acrylic resin paint (manufactured by Nippon Shokubai Co., Ltd., Polyment NK-380 (Tg = 100 ° C.)) as an organic solvent (toluene / methyl isobutyl ketone = as a resin composition for forming a protective layer). A coating solution diluted in a range of 10 to 100% in 3/1) was prepared and dried at a drying temperature of 40 ° C. for 5 seconds to form a protective layer having a thickness of 20 μm as Comparative Example 2.

(Comparative Example 3)
In Example 1, a silicon oxide thin film having a thickness of 400 nm was formed on one side of the substrate, and a protective layer was not provided as Comparative Example 3.

(Comparative Example 4)
In Example 1, after forming a silicon oxide thin film with a thickness of 400 nm on one side of the substrate, a water-based resin composition (polyvinyl alcohol 10% aqueous solution) was applied to form a protective layer of the water-based resin composition with a thickness of 1 μm. This was formed as Comparative Example 4. In Comparative Example 4, since the protective layer was not effective and the silicon oxide thin film was cracked, it was impossible to measure the oxygen transmission rate.

  Table 3 shows measured values of oxygen permeability of Examples 1 and 2 and Comparative Examples 1 to 4.

  According to the measurement results in Table 3, in Examples 1 and 2 relating to the gas barrier film according to the present invention having both the silicon oxide thin film and the protective layer, both are compared with Comparative Example 1 as it is as the base film. It can be seen that the oxygen permeability is reduced to 1/15 or less, and the oxygen gas barrier property is improved.

  Moreover, according to the measurement result of the oxygen transmission rate in Table 3, when the comparative example 2 in which the protective layer having no gas barrier property is provided on one side of the base material and the comparative example 1 without changing the base material, the oxygen transmission rate is It is almost the same, and it can be seen that this protective layer has no gas barrier property.

  Moreover, when the comparative example 3 which formed only the silicon oxide thin film on the single side | surface of the base material, and did not provide the protective layer, and the comparative example 1 with the base material as it is, oxygen transmission rate is reduced by half. It can be seen that only the oxide thin film has a low effect of improving the gas barrier property.

  Moreover, the scanning electron microscope which observed Example 1 of this invention which has a protective layer on a silicon oxide thin film, and Comparative Example 3 which did not provide the protective layer on a silicon oxide thin film observed the surface of the film Compared with the photograph, in Comparative Example 3, as shown in the photograph of FIG. 3, cracks (white lines appearing substantially in the horizontal direction in FIG. 3) were confirmed, whereas in Example 1, the surface was Almost homogeneous and no cracks were observed. Therefore, in Comparative Example 3, the gas barrier property is lowered due to gas permeation through the crack, whereas in Example 1, the gas barrier property of the silicon oxide thin film is exhibited without being impaired by the crack. Conceivable.

  In the present invention, as described above, a gas barrier layer of silicon oxide thin film containing carbon by plasma CVD is formed on at least one surface of a base material made of polyolefin having heat-fusibility. It was achieved by finding that an excellent oxygen gas barrier property can be improved only by forming a protective layer comprising a coating layer of a resin composition having no gas barrier property.

As mentioned above, although this invention has been demonstrated based on suitable embodiment, this invention is not limited to the above-mentioned example, Various modifications are possible in the range which does not deviate from the summary of this invention.
For example, you may laminate | stack the peeling film which gave the peeling process through the adhesive on the surface of the side in which the gas barrier layer of the base film is not formed.
In addition, a display layer of a packaging bag may be provided by laminating a film in which a printed layer printed with characters and designs and a surface coating layer is laminated on a protective layer formed on the silicon oxide thin film of the present invention. it can.

  As described above, the gas barrier film of the present invention uses a gas barrier layer made of a transparent silicon oxide thin film, and does not use a metal foil or a metal vapor deposited film. Further, since no harmful gas such as chlorine gas is generated even when incinerated, the burden on the environment is small, and therefore it can be suitably used as a packaging material for foods, pharmaceuticals, chemicals, medical instruments, electronic parts and the like.

It is typical sectional drawing which shows the gas barrier film of this invention. It is a scanning electron micrograph which observed the surface of the film which is a gas barrier film shown in Example 1 of this invention, and formed the protective layer in the silicon oxide thin film by plasma CVD. It is the scanning electron micrograph which observed the surface of the film which is only the silicon oxide thin film by plasma CVD shown in the comparative example 3 of this invention, and the protective layer is not formed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Gas barrier film, 2 ... Base material, 3 ... Silicon oxide thin film, 4 ... Protective layer.

Claims (5)

  A gas barrier layer of silicon oxide thin film containing carbon by plasma CVD is formed on at least one surface of a base material made of polyolefin having heat-fusibility, and substantially has gas barrier properties on the silicon oxide thin film. A gas barrier film comprising a protective layer comprising a coating layer of a resin composition that is not used.   2. The gas barrier film according to claim 1, wherein the resin composition is a resin composition substantially free of a vinylidene chloride copolymer, an ethylene-vinyl alcohol copolymer, and polyvinyl alcohol.   The gas barrier film according to claim 1 or 2, wherein the resin composition is water-insoluble.   The packaging material which comprises a packaging bag comprises the gas barrier film in any one of Claims 1-3 as at least one part, The packaging bag characterized by the above-mentioned.   Carbon produced by plasma reaction of organometallic silicon and oxygen in an inert gas in a vacuum glow discharge or atmospheric pressure glow discharge is applied to at least one surface of a base material made of polyolefin having heat-fusibility. A gas barrier film comprising: forming a gas barrier layer of a silicon oxide thin film containing a protective layer composed of a coating layer of a resin composition having substantially no gas barrier property on the silicon oxide thin film. Manufacturing method.

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