JPH05295528A - Production of gas barrier film - Google Patents

Abstract

PURPOSE:To produce a gas barrier film excellent in properties as a gas barrier, chemical resistance and transparency by vapor-depositing metallic silicon or silicon oxide on a plastic film substrate by ion plating. CONSTITUTION:A plastic film substrate 3 is continuously transferred through a cylindrical support 8 in a vacuum vessel 1 and an evaporating material 5 such as metallic Si or SiO2 is evaporated by heating with electron beams 7 from an electron gun 6. At the same time, a reactive gas such as O2 is introduced from a gas inlet 4 and high-frequency voltage is impressed on the substrate 3 from a power source 2 to cause electric discharge. Vapor of SiO2, etc., and gaseous O2 are ionized and a thin film of SiO2, etc., is formed on the film 3 by ion plating. The objective gas barrier film excellent in properties as a gas barrier, transparency, etc., is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of packaging materials for food and drink, medical products, etc., which are excellent in gas barrier properties against oxygen gas, carbon dioxide gas, etc., water vapor barrier properties, chemical resistance and transparency. , A method for producing a transparent gas barrier film useful in the field of electronic materials, etc.

[0002].

2. Description of the Related Art Aluminum vapor-deposited films obtained by vapor-depositing aluminum on a plastic film have been widely used as packaging materials for foods and the like because of their excellent flexibility and gas barrier properties. .. However, since it uses metallic aluminum, it is opaque and has poor weather resistance and chemical resistance. Also, the gas barrier property is not sufficient. Therefore, Japanese Patent Laid-Open No. 49-41469 proposes a method of forming a film of silicon oxide by a vapor deposition method. Although silicon oxide has the advantage of being transparent as compared with aluminum, it exhibits a yellowish brown color and is not sufficiently transparent. Moreover, the flexibility is low, and cracks and the like are likely to occur in the film. Therefore, the gas barrier property is not sufficient. For example, when SiO is used, the gas barrier property is improved as compared with SiO ₂ , but it is still not sufficient, and since a yellowish brown thin film is obtained, the visible light transmittance is poor. On the other hand, when SiO _{2 is formed} by a vapor deposition method, a film having good transparency can be obtained, but the gas barrier property is extremely poor.

Since all of these films are formed by a vapor deposition method, unevenness of the vapor deposition film itself, deterioration of the denseness of the film, and production, which are considered to be caused by nonuniformity of reaction during vapor deposition, are produced. If the gas barrier property is not sufficient due to the mechanical properties of the film such as cracks occurring in the formed film being low, or due to defects in the vapor-deposited film structure that are considered to have caused pinholes due to dust or the like on the film substrate. Conceivable.

Therefore, an object of the present invention is to provide a method for forming a transparent gas barrier film which is excellent in gas barrier property, chemical resistance and transparency.

[0005]

Means for Solving the Problems As a result of intensive studies to obtain an excellent gas barrier film, the present inventors have found that among the factors that hinder the improvement of barrier properties, the occurrence of cracks in a thin film. It was found that the ratio has a strong correlation with the adhesion of this thin film to the base film. Therefore, in order to improve the adhesion strength, it has been found that it is effective to use silicon and / or silicon oxide as the evaporation material and use an ion plating method performed under the condition of promoting the ionization of the evaporation material and the introduced gas. .. Further, regarding the above points and, it was also found that the good wraparound characteristics of the ion plating method, the high-density structure, and the like effectively act.

That is, the present invention is a method for producing a gas barrier film by forming a film on a plastic film substrate, wherein the film forming uses ion plating using metal silicon and / or silicon oxide as an evaporation material. The present invention provides a method characterized by being performed by a method.

The method of the present invention is a film forming method by an ion plating method. In the ion plating method,
A voltage is applied to the support of the plastic film substrate to generate a discharge and promote the ionization of the vaporized material and the introduced gas. At that time, metallic silicon and / or silicon oxide is used as the evaporation material. Examples of the silicon oxide include SiO, SiO ₂ , Si ₂ O ₃ , and Si ₃ O _4.
Etc. One kind or two or more kinds of silicon oxide can be used, and silicon and silicon oxide can be used in combination. In addition, a small amount of impurities such as C, H, N, Ar, and S may be contained. When two or more evaporation materials are used, they may be mixed in advance and heated and evaporated, or two or more heating sources may be arranged and heated separately. The heating method is not particularly limited, but may be resistance heating, electron beam heating, high frequency heating, hollow cathode heating, or the like.

The above evaporation material is formed into a film on a plastic film substrate. As a plastic film,
Although not particularly limited, for example, polyester such as polyethylene terephthalate and polybutylene terephthalate, polyamide, polyvinyl chloride, polyacrylonitrile, polycarbonate, polystyrene, polypropylene, polyethylene, saponified ethylene-vinyl acetate copolymer, aromatic polyamide, fluororesin, etc. It can be a film (including a copolymer in addition to a homopolymer) using the above as a raw material, or a laminated film containing one or more of these. Further, these films may be subjected to printing, coating with a silane coupling agent or the like, or surface treatment such as corona discharge treatment and plasma treatment. Further, it may be uniaxially stretched or biaxially stretched. Although the thickness of the film substrate is not particularly limited, for example, in the case of producing by a winding method, the thickness of the plastic film is
5 to 300 from the viewpoint of preventing wrinkles and cracks
It is preferably μm.

In the method of the present invention, a voltage is applied to the support of the above-mentioned film substrate to cause discharge. This promotes ionization of the vaporized material and the introduced gas. The support for the substrate is one for supporting the film substrate, and its material, shape, etc. are not particularly limited. For example, when the film is produced by the winding system, a stainless steel cooling can is used. The applied voltage may be direct current or alternating current. The AC frequency is preferably 50 Hz or higher. Further, the voltage may be applied only with the AC voltage, or the DC voltage may be superposed on it. Whether the applied voltage is an AC voltage or a DC voltage superimposed thereon, the voltage of the DC component induced in the substrate is preferably 0.15 to 6 kv. It is particularly preferably 0.2 to 3 kv.

Further, in order to accelerate the ionization of the gas and the vaporized material, arc discharge, a high frequency discharge method by L coupling, a high frequency discharge under a parallel flat plate, a microwave discharge and an ECR discharge, and a method using various ion sources, etc. Can also be combined with the above discharge method. In this case, the ionizing means to be combined may be different in the case of the evaporation material and the case of the introduced gas.

Next, as the introduced gas, oxygen, ozone,
Argon, nitrogen and the like can be used, but oxygen is preferably used. It may also be a mixed gas. When silicon is used as the evaporation material, it is particularly preferable to use oxygen.

In the method of the present invention, other conditions for ion plating are not particularly limited, and ordinary conditions can be used. For example, the following conditions can be used. Gas pressure: 1 × 10 ⁻⁴ to 1 × 10 ⁻³ Torr Further, in the case of the film winding system, the film conveying speed is 3 to 30 m / min.

The gas barrier film formed by the method of the present invention has a visible light transmittance of preferably 85% or more, more preferably 90% or more. The visible light transmittance is the transmittance obtained by subtracting the absorption by the film substrate in the wavelength range of 600 to 900 nm.

The gas barrier film formed by the method of the present invention may be used as a film integrated with a substrate as it is or may be processed into a bag, a tube or the like to be a packaging material such as food and drink, clothing and electronic materials, Gas barrier material,
It can be widely used as an electrically insulating material or a conductive material.

[0015]

The present invention will be described in more detail by the following examples. Example 1 5 kg of a sintered body of SiO 2 was used as the evaporation material, and oxygen gas (gas pressure: 1 × 10 ⁻⁴ torr) was used as the introduction gas. Using the apparatus of FIG. 1, the thickness was 75 μm. A film was formed on a polyethylene terephthalate film (PET) substrate of. An electron beam method was used as a heating method, and an ion plating film was formed by applying a power of 13.56 MHz to the support of the substrate at 1 kW. The other film forming conditions were as follows. Film transport speed: 10 m / min Support temperature of substrate: 0 ° C. Thus, a gas barrier film having a film thickness of 1000 Å was obtained on the substrate. The gas barrier properties of the obtained gas barrier film with respect to oxygen gas and water vapor and the visible light transmittance were measured in a state of being formed on a PET substrate. The results are shown in Table 1.

The visible light transmittance is 600 to 90 wavelengths.
It is the transmittance obtained by subtracting the absorption in the PET film in the range of 0 nm. The gas barrier property against oxygen gas and water vapor is a value measured by the same pressure method, and
It is the volume or weight of the amount of gas that has passed through a membrane having a constant area (m ² ) in one day at 5 ° C., 1 atm and 0% RH. Example 2 An ion plating film was formed in the same manner as in Example 1 except that a SiO ₂ sintered body was used as the evaporation material, and a film having a film thickness of 1000 Å was obtained. The obtained film was evaluated in the same manner as in Example 1, and the results are shown in Table 1.
It was shown to. Comparative Example 1 A film was formed on a PET film substrate having a thickness of 75 μm by a vapor deposition method using a sintered body of SiO as an evaporation material.
The vapor deposition conditions were as follows. Degree of vacuum: 1 × 10 ⁻⁵ torr Film transport speed: 10 m / min Substrate support temperature: 0 ° C. The obtained film was evaluated in the same manner as in Example 1, and the results are also shown in Table 1.

[0017]

[Table 1] Table 1 Visible light transmittance Oxygen transmittance ^{* 1} Water vapor transmittance ^{* 2} (%) Example 1 90 0.45 0.30 Example 2 92 1.00 0.90 Comparative Example 1 68 2.2 2.0 * 1 Unit: ml / day · m ²・ atm * 2 Unit: g / day ・ m ²・ atm

[0018]

According to the present invention, it is possible to provide a transparent gas barrier film having high gas barrier properties and excellent transparency. The film of the present invention can be used in a wide range of fields including various packaging applications and has high industrial utility.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an apparatus used for forming a film of the present invention.

[Explanation of symbols]

1 is a vacuum chamber, 2 is a high frequency power source, 3 is a plastic film substrate, 4 is a gas inlet,
Is an evaporation material, 6 is an electron gun, 7 is an electron beam, 8 is a support for a film substrate, 9 is an ion source, and 10 is a shield plate.

Claims (1)

[Claims] 1. A method for producing a gas barrier film by forming a film on a plastic film substrate, which is carried out by an ion plating method using metal silicon and / or silicon oxide as an evaporation material. A method characterized by being treated.