JP4936064B2 - Gas barrier film and method for producing the same - Google Patents

Description

  The present invention relates to a gas barrier film having excellent gas barrier properties and transparency and a method for producing the same. The gas barrier film of the present invention is suitably used for protective films for display media such as displays, as well as food and pharmaceutical packaging materials.

  The performance required for food and pharmaceutical packaging materials includes gas barrier properties that prevent permeation of oxygen and water vapor, which cause deterioration of contents. Therefore, a gas barrier film obtained by depositing aluminum on a polymer resin film such as aluminum foil or polyethylene terephthalate having excellent safety has been used. However, these aluminum foils and aluminum-deposited films use metal, so they lack transparency and cannot be used to confirm the contents. Also, metal detectors, microwave heating cannot be used, and the environment during disposal. There was a problem such as load.

In order to solve these problems, a transparent deposited film on which an inorganic oxide is deposited is proposed. Examples of the inorganic oxide of the vapor deposition material include Al ₂ O ₃ , SiO, and MgO. It is known that transparent vapor deposition films using these have transparency in addition to gas barrier properties.

However, the SiOx vapor-deposited film on which SiO is vapor-deposited exhibits a yellow color, making it difficult to grasp the correct color when used as a protective film for packaging materials and display media (see Patent Documents 1 and 2).
Japanese Patent Laid-Open No. 3-100164 JP-A-4-333767

When using a conventional SiO vapor deposition material and evaluating the water vapor permeability and transparency of a gas barrier film in which, for example, 300 nm thick SiOx is deposited using a polyethylene terephthalate having a thickness of 25 μm as a base film, 1.4 g / m ² / While it has a barrier property of about a day, its light transmittance is as low as 45%, making it difficult to achieve both high gas barrier properties and transparency maintenance.

It is known that the value of x indicating the degree of oxidation particularly affects the transparency and barrier properties of SiOx deposited films deposited with SiO. This does not apply to the deposited SiOx film, but the existing SiOx includes SiO (black), Si ₃ O ₄ (brown), Si ₂ O ₃ (yellow) SiO ₂ (colorless). Is different. In other words, the larger the value of x, the more transparent it becomes. To create a transparent gas barrier film using SiO as the deposition material, oxygen is introduced and reacted with the evaporated SiO to form SiOx on the base film. There was a problem in controlling the oxygen partial pressure.

  Accordingly, an object of the present invention is to provide a gas barrier film having excellent gas barrier properties while exhibiting high transparency without exhibiting yellow without introducing a reaction gas in a gas barrier film using SiOx as an evaporation material, and its production In providing a method.

The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 uses an SiOx vapor deposition material on at least one surface of a base film, and an electron in an atmosphere in which no reaction gas is introduced. A gas barrier film manufacturing method for forming a SiOx film by a beam (EB) vapor deposition method,
SiO ₂ for adjusting the bulk density is mixed in the SiOx vapor deposition material ,
The SiOx vapor deposition material has a diffraction pattern of crystalline SiO ₂ ;
And the bulk density with respect to the true density of the SiOx vapor deposition material is 71 % or more and less than 80%.
This is a method for producing a gas barrier film.
Invention of Claim 2 is a gas barrier film manufactured using the manufacturing method of Claim 1,
The SiOx film has a thickness of 200 nm or less.
The invention described in claim 3 is characterized in that the light transmittance in the wavelength range of 350 to 800 nm is 73% or more, and the water vapor transmission rate is 2.0 g / m ² / day or less. This is a gas barrier film.

  According to the present invention, in a gas barrier film using SiOx as an evaporation material, a gas barrier film having excellent gas barrier properties while exhibiting high transparency without exhibiting yellow without introducing a reaction gas and a method for producing the same Is provided.

  As vapor deposition methods for inorganic oxides such as SiO, physical vapor deposition (PVD) such as vacuum vapor deposition and sputtering method similar to aluminum vapor deposition and chemical vapor deposition (CVD) such as plasma CVD method are known. . Considering that the base film is a polymer resin film and that it is necessary to perform continuous deposition by winding for cost reduction, the vacuum deposition method is suitable, and the melting point of SiO is 1700 ° C compared with aluminum Since it has a high melting point, an electron beam (EB) method using an electron gun is preferable among the vacuum evaporation methods in order to efficiently evaporate the SiOx evaporation material. In addition, according to this method, it becomes possible to omit the heating of the crucible and the vapor deposition material as a pre-deposition step necessary for the resistance heating method, and the vapor deposition material can be heated locally and rapidly, thereby increasing the productivity. Can also be expected.

  Examples of the base film used in the present invention include a polymer resin film, which is not particularly limited as long as it is transparent and can hold a SiOx deposited film. Examples thereof include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin resins such as polyethylene (PE) and polypropylene (PP), and polyamide resins such as nylon-6 and nylon 66. Although the thickness of these polymer resin films is not particularly limited, it can be used in a thickness of 3 to 200 μm, and a thickness of 12 to 30 μm is particularly preferable.

  As the shape of the SiOx vapor deposition material used in the present invention, if it is powdery or granular, the vapor deposition material particles easily scatter (splash) at the time of EB irradiation and collide with the base film to cause a through hole (pinhole). End up. Further, it is not preferable to simply mold in a mold because handling properties are poor, and when a material is cracked during vapor deposition, splash is likely to occur from the crack. Therefore, it is possible to maintain the shape of the vapor deposition material by sintering at the same time as molding, or sintering after molding, and it can be expected to suppress splash by changing material properties such as bulk density and particle size. . Moreover, since it is excellent in handling property, it can be mass-produced.

The SiOx vapor deposition material used in the present invention needs to have a crystalline SiO ₂ diffraction pattern. Diffraction pattern of the SiO ₂ is made to determine whether the SiO ₂ are mixed is crystalline in SiOx deposition material. By SiO ₂ are mixed in the SiO vapor deposition material is because it is possible to form the SiOx film without introducing a reaction gas.

  There are two methods for forming the vapor deposition material, such as the casting method and rubber pressing method, and the hot pressing method and hot isostatic pressing method (HIP method). When the latter method is used, a high-density sintered body having a uniform particle size with no abnormal grain growth can be obtained because the temperature at which densification occurs, but the present invention is not particularly limited. The atmosphere during sintering includes a vacuum atmosphere, a nitrogen atmosphere, an air atmosphere, and the like, but is not particularly limited in the present invention.

The SiOx vapor deposition material used in the present invention needs to have a bulk density of 70% or more and less than 80% with respect to the true density. The bulk density can be adjusted by combining particles having different particle sizes and mixing silica sol containing amorphous SiO ₂ particles. If the bulk density is too small, the size of the SiOx vapor deposition material becomes large and the crucible size may be limited. If the bulk density is too large, the material may be cracked by thermal shock during EB irradiation. . Therefore, the bulk density relative to the true density of the SiOx vapor deposition material in the present invention needs to be specified as described above.
The bulk density relative to the true density in the present invention is a value measured by the Archimedes method.

The SiOx vapor-deposited film produced by the CVD method has a transparent and high barrier property, but the one produced by the vacuum vapor-deposition method exhibits a yellow color but becomes more transparent as the x value approaches 1 However, as the value of x decreases to 2 and the transparency increases, the barrier property deteriorates. This is because the SiOx evaporated by heating due to the principle of the vapor deposition method is physically deposited on the base film, and as a result, the gap during the deposition becomes a factor determining the barrier performance. Therefore, if the value of x is small, the interatomic network of SiOx on the film becomes dense and expresses a barrier property. Conversely, if the value of x is large, the interatomic network becomes sparse and the barrier property does not appear. The In the present invention, the SiO ₂ O component mixed into the SiO vapor deposition material as a bulk density adjusting agent results in an increase in the value of x, and transparency is obtained without introducing a reaction gas.

  The portion of the SiOx film that contributes to the film thickness is large for the gas barrier property, and if it is too thin, the barrier property is not exhibited because it is not formed on the entire substrate film. On the other hand, if the film thickness is extremely thick, cracks are generated on the surface of the deposited film, resulting in a decrease in barrier properties and an increase in curl, resulting in poor handling properties. Therefore, considering these points, the thickness of the SiOx film is preferably 300 nm or less, more preferably 200 nm or less, and particularly preferably 10 to 200 nm.

The gas barrier film of the present invention has a light transmittance of 73% or more in a wavelength range of 350 to 800 nm and a water vapor transmission rate of 2.0 g / m ² / day or less.

  EXAMPLES Hereinafter, although an Example and a comparative example further demonstrate this invention, this invention is not restrict | limited to the following example.

<Example 1>
Using a batch-type vacuum vapor deposition system with an electron beam heating method, SiO ₂ is mixed as a bulk density adjusting agent, and the SiOx vapor deposition material with a bulk density ratio of 71% to the true density is evaporated by electron beam heating to form a film. A SiOx film having a thickness of 189 m was formed at an internal pressure of 1.0 × 10 ⁻³ Pa. However, the deposition conditions at this time are as follows.
Acceleration voltage: 5.9kV
Emission current: 0.15 A
Base film: PET film thickness 25μm (T60 manufactured by Toray Industries, Inc.)

<Example 2>
Using a batch-type vacuum vapor deposition system with an electron beam heating method, SiO ₂ is mixed as a bulk density adjusting agent, and the SiOx vapor deposition material with a bulk density ratio of 78% to the true density is evaporated by electron beam heating to form a film. A SiOx film having a thickness of 192 nm was formed at an internal pressure of 1.0 × 10 ⁻³ Pa. The deposition conditions for SiOx are the same as in Example 1.

<Example 3>
Using a batch-type vacuum vapor deposition system with an electron beam heating method, SiO ₂ is mixed as a bulk density adjusting agent, and the SiOx vapor deposition material with a bulk density ratio of 78% to the true density is evaporated by electron beam heating to form a film. A SiOx film having a thickness of 62 nm was formed at an internal pressure of 1.0 × 10 ⁻³ Pa. The deposition conditions for SiOx are the same as in Example 1.

<Comparative Example 1>
Using a batch-type vacuum vapor deposition system with an electron beam heating method, SiO ₂ is mixed as a bulk density adjusting agent, and the SiOx vapor deposition material with a bulk density ratio of 78% to the true density is evaporated by electron beam heating to form a film. A SiOx film having a thickness of 310 nm was formed at an internal pressure of 1.0 × 10 ⁻³ Pa. The deposition conditions for SiOx are the same as in Example 1.

<Comparative example 2>
Using an electron beam heating batch-type vacuum deposition apparatus, SiO ₂ is mixed as a bulk density adjusting agent, and the SiOx deposition material with a bulk density ratio of 80% to the true density is evaporated by electron beam heating. A SiOx film having a thickness of 228 nm was formed at a pressure of 1.0 × 10 ⁻³ Pa. The deposition conditions for SiOx are the same as in Example 1.

<Comparative Example 3>
Using a batch-type vacuum deposition apparatus of the electron beam heating method, a SiOx deposition material having a bulk density ratio of 72% to the true density is evaporated by electron beam heating, and the pressure during film formation is 1.0 × 10 A SiOx film having a thickness of 197 nm was formed at ⁻³ Pa. The deposition conditions for SiOx are the same as in Example 1.

<Comparative example 4>
Using a batch-type vacuum deposition apparatus of the electron beam heating method, a SiOx deposition material having a bulk density ratio of 72% to the true density is evaporated by electron beam heating, and the pressure during film formation is 1.0 × 10 A SiOx film having a thickness of 44 nm was formed at ⁻³ Pa. The deposition conditions for SiOx are the same as in Example 1.

The evaluation method of the SiOx film produced by the Example and the comparative example is shown below.
Light transmittance: Measured using a spectrophotometer U-4000 (manufactured by Hitachi, Ltd., measurement wavelength 350 nm).
Water vapor permeability: Measured by the cup method at 40 ° C. and 90% based on the JISZ0208 method.
Film thickness: Using a fluorescent X-ray analyzer (manufactured by Rigaku Corporation), the film thickness of SiOx was determined from the result of a calibration curve obtained by measuring a similar sample with TEM in advance.
Crystal structure: Measured using an X-ray diffractometer RINT-ULTIMA3 (manufactured by Rigaku Corporation).
Color: Visual judgment.
The results are shown in Table 1.

Light transmittance: Light transmittance [%] at 350nm wavelength including PET film with 25μm thickness
Shows the lowest light transmittance at 350 nm in the wavelength range of 350 to 800 nm (Figure 1)

  As shown in Table 1, with respect to water vapor barrier properties, Examples 1 to 3 and Comparative Examples 1, 2, and 4 show almost the same values. In Examples 1 to 3, the light transmittance is in a wavelength range of 350 to 800 nm. It was as high as 73% or more, and it was possible to achieve both water vapor barrier properties and transparency. However, Comparative Example 2 resulted in a low light transmittance of 20% or less, and Comparative Example 4 obtained almost the same properties as the other samples despite the thin film thickness, but the light transmittance was 52.8%. Because of its pale yellow color, it was difficult to maintain both high gas barrier properties and transparency.

In Example 2, when the ratio of the bulk density to the true density was 78%, the water transmittance was 1.8 g / m ² / day, but the light transmittance was 73.9% and high transparency was able to be exhibited. In Comparative Example 2, when the ratio of the bulk density to the true density was 80%, the light transmittance was as low as 14.8% while the water vapor transmission rate was 2.0 g / m ² / day. Further, in Comparative Example 3 not including the SiO ₂ diffraction pattern, the water vapor transmission rate is 1.3 g / m ² / day when the ratio of the bulk density to the true density is 72%, whereas the light transmittance is 15.6%. The result was low.

Comparing Example 2 and Comparative Example 1, in Comparative Example 1, when the SiOx thickness was 310 nm, the water vapor permeability increased from 1.8 g / m ² / day to 1.6 g / m ² / day as the water vapor barrier property increased. The light transmittance increased from 73.9% to 72.6%, but the transparency was maintained. However, the curl was strong and the handling property was poor, so the film thickness is preferably 200 nm or less.

  According to the present invention, there is provided a uniform transparent gas barrier film that does not require a control operation of an oxygen partial pressure required when a reaction gas is used, has a high light transmittance, and suppresses the transmission of water vapor and has a barrier property. It becomes possible. The gas barrier film of the present invention is suitably used for protective films for display media such as displays, as well as food and pharmaceutical packaging materials.

It is a graph of the light transmittance measured by the Example and the comparative example.

Claims (3)

A method for producing a gas barrier film in which an SiOx film is formed by an electron beam (EB) vapor deposition method in an atmosphere in which a reaction gas is not introduced on at least one surface of a base film,
SiO ₂ for adjusting the bulk density is mixed in the SiOx vapor deposition material ,
The SiOx vapor deposition material has a diffraction pattern of crystalline SiO ₂ ;
And the bulk density with respect to the true density of the SiOx vapor deposition material is 71 % or more and less than 80%.
A method for producing a gas barrier film, comprising: A gas barrier film produced using the production method according to claim 1,
A gas barrier film, wherein the SiOx film has a thickness of 200 nm or less. The gas barrier film according to claim 2, wherein the light transmittance in a wavelength range of 350 to 800 nm is 73% or more, and the water vapor transmission is 2.0 g / m ² / day or less.

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