JP2001064424A - Transparent gas barrier film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aluminum oxide-based gas-barrier film excellent in retort resistance, flexing resistance and gas-barrier properties as a packing film. SOLUTION: This gas-barrier film has an aluminum oxide thin film formed on a plastic film. The thin film has 2.70-3.30 specific gravity. As a result, the gas-barrier film excellent in gas-barrier properties, having high retort resistance and flexing resistance, and thereby totally excellent in practical characteristics can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a gas barrier material, a retort-resistant material, and a gel material having excellent properties as a packaging material or a gas barrier material which is required to be airtight for food, medicine, electronic parts and the like. It is about the film that you have.

[0002]

2. Description of the Related Art Films having excellent gas barrier properties include those obtained by laminating aluminum on a plastic film and those coated with vinylidene chloride or ethylene vinyl alcohol copolymer. Also,
As a device using an inorganic thin film, a device obtained by laminating a silicon oxide, an aluminum oxide thin film, or the like is known.

[0003]

However, such a conventional gas barrier film has the following problems. Although the aluminum laminate is excellent in economics and gas barrier properties, it is opaque, so that the contents at the time of packaging cannot be seen, and it cannot be used in a microwave oven because it does not transmit microwaves. Those coated with vinylidene chloride or ethylene vinyl alcohol copolymer do not have sufficient gas barrier properties against water vapor, oxygen, etc., and the decrease is remarkable especially at high temperature treatment. In addition, with respect to vinylidene chloride, there is generation of chlorine gas at the time of incineration, and there is also a concern about the influence on the global environment.

Japanese Patent Publication No. 51-48511 proposes a gas barrier film in which SI _x O _y (for example, SiO ₂ ) is vapor-deposited on the surface of a synthetic resin body, but an SiO _x system (x = 1) having good gas barrier properties is proposed. 0.5 to 1.8) have a slightly brown color, which is insufficient as a transparent gas barrier film. On the other hand, as a material mainly composed of aluminum oxide, it is completely colorless and transparent and chemically stable,
In addition, the material cost is low, and it can be said that it is superior as a gas barrier film for packaging.
101428) have insufficient gas barrier properties and have a problem in bending resistance. Flexibility affects the deterioration of barrier properties in the subsequent processes (lamination, printing, bag making, etc.) after film formation and handling, etc. In the case of aluminum oxide, the film itself is brittle, so care should be taken when handling it. Is required. In general, a gas barrier film using a thin film requires a certain thickness of the thin film in order to improve the boilability and retort resistance. On the other hand, in order to improve mechanical properties such as bending resistance, the gas barrier film is as thin as possible. However, in the case of an aluminum oxide thin film, there is a problem that the preferable range is particularly narrow. As described above, at present, there is no aluminum oxide-based transparent gas barrier film having both sufficient oxygen barrier properties and retort resistance, and having high bending resistance.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an aluminum oxide gas barrier film which is excellent in gas barrier properties and retort resistance and has high bending resistance. That is, the present invention is a gas barrier film in which an aluminum oxide thin film is formed on a plastic film, wherein the specific gravity of the thin film is 2.70 to 3.30.

[0006] The plastic film referred to in the present invention is:
A film obtained by melt-extruding an organic polymer and stretching, cooling, and heat setting in the longitudinal direction and / or the width direction as necessary. Examples of the organic polymer include polyethylene, polypropylene, and polyethylene terephthalate. , Polyethylene-2,6-naphthalate, nylon 6, nylon 4, nylon 66, nylon 12, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, wholly aromatic polyamide, polyamideimide, polyimide, polyetherimide, polysulfone, Examples include polyphenylene sulfide and polyphenylene oxide. These (organic polymer) organic polymers may be copolymerized or blended in small amounts with other organic polymers.

Further, known additives such as an ultraviolet absorber, an antistatic agent, a plasticizer, a lubricant, and a coloring agent may be added to the organic polymer, and the transparency thereof is not particularly limited. However, when used as a transparent gas barrier film, those having a transmittance of 50% or more are preferred. The plastic film of the present invention may be subjected to corona discharge treatment, glow discharge treatment, or other surface roughening treatment prior to laminating the thin film layer, as long as the object of the present invention is not impaired. ,Also,
Known anchor coat treatment, printing, and decoration may be applied. The thickness of the plastic film of the present invention is preferably in the range of 5 to 500 μm, more preferably 8 to 300 μm.

The aluminum oxide thin film in the present invention is considered to be composed of Al, AlO, Al ₂ O _3, etc., and their ratios also differ depending on the preparation conditions. In this ingredient,
Minor amount within the range where characteristics are not impaired (at most 3% for all components)
%). The thickness of the thin film is not particularly limited, but is preferably in the range of 50 to 8000 ° from the viewpoint of gas barrier properties and flexibility. For the preparation of such an aluminum oxide thin film, PV such as a vacuum deposition method, a sputtering method and an ion plating method is used.
Method D (physical vapor deposition), CVD (chemical vapor deposition), or the like is used as appropriate. For example, in a vacuum deposition method, Al or Al ₂ O ₃ or the like is used as a deposition source material,
The heating method includes resistance heating, high-frequency induction heating,
Electron beam heating or the like can be used. Further, oxygen, nitrogen, water vapor, or the like may be introduced as a reactive gas, or reactive vapor deposition using means such as ozone addition or ion assist may be used. Further, the production conditions may be changed as long as the object of the present invention is not impaired, such as applying a bias to the substrate, increasing the substrate temperature, or cooling.
The same applies to other production methods such as a sputtering method and a CVD method. The product of the present invention may be used as it is, or may be used by laminating or coating another organic polymer film or a thin layer.

The specific gravity referred to in the present invention refers to the ratio of the mass of a substance occupying a certain volume at a certain temperature to the mass of a standard substance having the same volume (water at 4 ° C.). The measurement of specific gravity is
Normally, the mass and volume of the object may be measured, and the ratio of the mass to the same volume of water at 4 ° C. may be determined. Then, first, the thin film is peeled off from the substrate or only the substrate is dissolved to form a single film consisting of only the thin film.
It is desirable to use a specific gravity measurement method as described in 7112). For example, in the flotation method, a sample is immersed in a solution having a known specific gravity, and the specific gravity of the thin film can be measured from the flotation state. As this solution, a mixed solution of carbon tetrachloride and bromoform, methylene iodide, or the like can be used. The specific gravity value can also be measured by a density gradient tube method in which a single film is immersed in a solution having a continuous density gradient.

When the specific gravity value of the thin film thus obtained is smaller than 2.70, the structure of the aluminum oxide thin film becomes coarse and sufficient gas barrier properties cannot be obtained.
When the specific gravity of the thin film is more than 3.30, the initial gas barrier properties after film formation are excellent,
The film becomes too hard, and the mechanical properties, especially the gelbo properties, are inferior.
The gas barrier property after treatment is greatly reduced, and is not suitable for use as a gas barrier film. For the above reasons, the specific gravity of the silicon oxide-based thin film preferable as the gas barrier film is 2.70 to 3.30, and more preferably 2.70.
80 to 3.20.

Next, the present invention will be described with reference to examples. Example 1 As a deposition source, particulate Al having a size of about 3 to 5 mm
_{Using 2} O ₃ (purity 99.9%), by electron beam evaporation,
12 μm thick PET film (Toyobo Co., Ltd .: E50
07), an aluminum oxide-based gas barrier thin film was formed thereon. An electron gun (hereinafter, an EB gun) is used as a heating source,
The emission current was set to 0.8 to 1.8A. The film feed speed was changed from 40 to 100 m / min,
A 0-5000 mm thick film was made. The vapor pressure was changed by changing the supply amount of oxygen gas and changing the conditions from 1 × 10 ⁻⁵ to 8 × 10 ⁻³ Torr.

The specific gravity of the film thus obtained is determined by PET.
After dissolving the film, the measurement was performed by the floatation / sedimentation method. Further, the unstretched polypropylene film (OPP film) having a thickness of 40 μm is dry-laminated with a two-component curing type polyurethane adhesive (thickness of 2 μm) to the composite film on the PET, and A plastic film for packaging for application of the invention was obtained. After subjecting this packaging film to retort treatment (120 degrees × 30 minutes) or gelbo treatment, the oxygen barrier properties were measured.

Oxygen Permeability Measurement Method The oxygen permeability of the prepared gas barrier film is measured by an oxygen permeability measuring device (OX-TRAN manufactured by Modern Controls).
100). Test method for flex fatigue resistance (hereinafter referred to as gelbo property) The flex fatigue resistance was evaluated using a so-called gelbo flex tester (manufactured by Rigaku Corporation). The conditions are (MIL-B131H) with 112 inch × 8 inch
h into a cylindrical shape having a diameter of 3 (1/2) inch,
Both ends are held, the initial gripping interval is 7 inches, the stroke is 3 (1/2) inch, and a twist of 400 degrees is applied. The reciprocating motion of this operation is repeated 40 times / min.
At a temperature of 20 ° C. and a relative humidity of 65%.
The oxygen transmittance measured in this way was very excellent, around 1.0 cc. Further, the result after 100 times of the gelbo test also showed a rise of only about 2 cc, and a gas barrier film having excellent overall characteristics was obtained.

Comparative Example 1 An aluminum oxide-based gas barrier thin film was formed by EB vapor deposition in the same manner as in Example 1.
Oxygen barrier properties after specific gravity measurement and retort treatment or gelbo treatment were measured. As a result, one of the oxygen barrier properties, retort resistance, and gelbo properties became insufficient, and the overall judgment was poor.

Example 2 As an evaporation source, particulate Al having a size of about 3 to 5 mm was used.
(Purity: 99.99%) and a high-frequency induction heating evaporation method using a PET film having a thickness of 12 μm (Toyobo Co., Ltd .: E
5100), an aluminum oxide-based gas barrier thin film was formed. The high-frequency power at that time was set to 2 to 5 KW, and the film feed speed was changed to 20 to 150 m / min.
500-4000 mm thick films were made. The vapor pressure can be changed from 1.0 × 10 ⁻⁵ to 8 × 10 by changing the supply amount of oxygen gas.
^The conditions were changed to ^-3 Torr. The specific gravity of the thus obtained film was measured after dissolving the PET film. In the same manner as in the following (Example 1), a packaging film was prepared, and the oxygen barrier property was measured.

Comparative Example 2 An aluminum oxide-based gas barrier thin film was formed by a high-frequency induction heating vapor deposition method as in Example 2, and the obtained sample was subjected to specific gravity measurement and retort treatment, or
The oxygen barrier property after the gelbo treatment was measured. As a result, one of the oxygen barrier properties, retort resistance, and gelbo properties became insufficient, and the overall judgment was poor.

Example 3 Using an Al ₂ O ₃ target (purity: 99.99%), an aluminum oxide-based gas barrier thin film was formed on a 24 μm thick PET film (Toyobo Co., Ltd .: E5000) by high frequency sputtering. Was formed. The film feed speed is 0.
The film thickness was changed from 0.5 to 2 m / min to form a film having a thickness of 500 to 4000 mm. The supply amounts of the argon gas and the oxygen gas were changed, and the oxidizing atmosphere and the vacuum pressure during sputtering were changed. Vacuum pressure: 2 to 100 mTorr, sputtering power: 3
８8 KW. After measuring the specific gravity of the film thus obtained, a packaging film was prepared and the oxygen barrier properties were measured in the same manner as in Example 1.

Comparative Example 3 An aluminum oxide-based gas barrier thin film was formed by high-frequency sputtering in the same manner as in Example 3, and the resulting sample was subjected to specific gravity measurement and retort treatment, or oxygen barrier after gelbo treatment. Sex was measured. As a result, one of the oxygen barrier properties, retort resistance, and gelbo properties became insufficient, and the overall judgment was poor.

Example 4 and Comparative Example 4 An aluminum oxide-based gas barrier film was formed on a polyimide film by EB vapor deposition using granular Al ₂ O ₃ as a vapor deposition source material as in Example 1. At this time, the deposition conditions, the substrate temperature (room temperature to 150 degrees) and the like are changed,
A film having a changed specific gravity was prepared. Specific gravity of the obtained sample,
When the barrier properties and the Guerbo properties were measured, the film having a too large specific gravity had excellent barrier properties, but was greatly deteriorated by the Guerbo properties, and was inferior in the properties of the gas barrier film.

[0020]

The gas barrier film in which an aluminum oxide-based thin film is formed on a plastic film,
By setting the specific gravity of the thin film to 2.70 to 3.30, the gas barrier property is excellent, and the retort resistance and the flexibility are high.
An aluminum oxide-based gas barrier film having excellent practical characteristics can be provided.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

[Table 3]

Continued on the front page (72) Inventor Seiji Iseki 2-1-1 Katata, Otsu-shi, Shiga Prefecture Inside Toyobo Co., Ltd. (72) Inventor Toshiyuki Otani 2-1-1 Katata, Otsu-shi, Shiga Toyobo Co., Ltd. (72) Inventor Hideomi Kobe 2-1-1 Katata, Otsu, Shiga Prefecture Toyobo Co., Ltd. (72) Inventor Yozo Yamada 2-1-1 Katata, Otsu City, Shiga Prefecture Toyobo Stock Inside the company research institute

Claims (1)

[Claims] 1. A gas barrier film in which an aluminum oxide thin film is formed on a plastic film, wherein the specific gravity of the thin film is 2.70 to 3.30.