JPS63222849A - Film for packaging - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a packaging film. More specifically, the present invention relates to a packaging film with excellent gas barrier properties and transparency.

[Prior Art] Conventionally, as a packaging film with excellent gas barrier properties, a plastic film in which silicon oxide is vapor-deposited on at least one side is known (Japanese Patent Publication No. 53-12953).

A film deposited with silicon oxide has better gas barrier properties than a plastic film provided with a vinylidene chloride-based or polyvinyl alcohol-based coating layer.

[Problems to be Solved by the Invention] However, the conventional gas barrier packaging films on which silicon oxide is vapor-deposited have the following problems. That is, if the thickness of the deposited film is increased in order to improve gas barrier properties, or if the deposited film undergoes dimensional changes due to moisture absorption, cracks or cracks will occur in the silicon oxide layer, resulting in a significant decrease in gas barrier properties.

In addition, the flexibility is insufficient, and when the vapor-deposited film is bent, stretched, or molded, cracks occur and gas barrier properties are often deteriorated.

In order to improve this drawback, the present inventors have already proposed a packaging film characterized by providing a thin layer of amorphous aluminum oxide on a transparent plastic film substrate. -242070>.

However, aluminum oxide 11m tends to have a porous structure because it is not easy to control the conditions during its formation, and for this reason, when the aluminum oxide thin layer is thin, the gas barrier properties deteriorate, especially water vapor. It was found that there was a problem in that the barrier properties were significantly reduced.

The object of the present invention is to provide a packaging film that does not have the above drawbacks, that is, is transparent and has excellent oxygen gas barrier properties and water vapor gas barrier properties.

Means for Solving Problems L, that is, the present invention is a packaging film characterized by providing a thin layer of aluminum oxide and aluminum hydroxide on a transparent plastic film substrate.

Examples of the transparent plastic film used in the present invention include polyolefins such as polyethylene, polypropylene, and polybutene, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene-2,6-naphthalate, nylon 6, and nylon 1.
Examples include polyamides such as No. 2, polycarbonate, polystyrene, polyvinyl chloride, polyvinylidene chloride, aromatic polyamides, and polyimides. Further, it may be a copolymer with these copolymers or other organic polymers, or it may contain other organic polymers.

Known additives such as antistatic agents, ultraviolet absorbers, plasticizers, lubricants, colorants, etc. may be added to these organic polymers. These transparent plastic films are preferably stretched in terms of strength, elongation, thermal properties, dimensional stability, etc., but may be unstretched.

As for the light transmittance of the plastic film of the present invention, it is desirable that the total light transmittance in white light is at least 40% or more, preferably 60% or more, more preferably 70% or more, and most preferably 80% or more. Known additives such as colorants are preferably added within this range.

The transparent plastic film of the present invention is produced by forming a thin layer of aluminum oxide and aluminum hydroxide.
Surface treatments such as corona discharge treatment, flame treatment, plasma treatment, glow discharge treatment, and surface roughening treatment, as well as known anchor coating treatment, may be performed, or the film may be laminated with other plastic films.

The thickness of the transparent plastic film of the present invention is not particularly limited, but it is preferably in the range of 3 to 400 μm, and more preferably in the range of 5 to 200 μm in terms of mechanical strength and flexibility.

A thin layer of aluminum oxide and aluminum hydroxide is formed on such a transparent plastic film substrate.

The aluminum oxide referred to in the present invention is AMO.

Aff 202, 80, 203 Nat (D7) I, t
Miniram (DH compound), but in the present invention, Aα203 is preferable from the viewpoint of transparency.Aluminum hydroxide refers to AD, (OH)3.AffO(OH>”
:c Which hydroxide is it?

In addition, aluminum and copper may be added to 1G of aluminum oxide within a range that does not impair transparency and gas barrier properties.

It is permissible for trace amounts of impurities such as metals such as iron, tungsten, and molybdenum, and zirconium oxide, magnesium oxide, tungsten oxide, molybdenum oxide, and boron nitride to be included.

The thickness of the thin layer made of aluminum oxide and aluminum hydroxide is selected depending on the substrate used and the purpose, but in the present invention, it is preferably in the range of 30 to 5000.
Preferably 50 to 2000 people, more preferably 100 people
People ~i ooo people is desirable. If it is less than 30 people, the gas barrier properties will not be sufficient, and if it is more than 5,000 Å, the flatness will be impaired, such as curling if the base film is extremely thin, such as 15 μm or less.

The ratio of aluminum oxide to aluminum hydroxide is preferably in the range of 90:10 to 10:90 by weight, more preferably in the range of 80:20 to 20:80.

In the present invention, various methods can be used to provide a thin layer of aluminum oxide and aluminum hydroxide on a transparent plastic film substrate, including the following:
It is not necessarily limited to these.

■ A method of forming a film consisting of aluminum oxide and aluminum hydroxide using a mixture of aluminum oxide and aluminum hydroxide as raw materials by vacuum evaporation such as electron beam evaporation, ion blating, or sputtering such as high-frequency magnetron sputtering.

■ Using aluminum oxide as a raw material, a film made of aluminum oxide is formed by vacuum evaporation such as electron beam evaporation, ion blating, sputtering, etc.
Then, a part of the aluminum oxide is transformed into aluminum hydroxide through heat treatment under high humidity.

(2) Using aluminum as a raw material, a film made of aluminum oxide was formed by so-called reactive vapor deposition, reactive ion blasting, and reactive sputtering, in which film formation was performed while supplying oxygen gas.

Then, a method of forming a mixed film of aluminum oxide and aluminum hydroxide through wet heat treatment, etc.

■ Using aluminum as a raw material, an aluminum film is formed by vacuum evaporation, ion blating, sputtering, etc., and then this is transformed into a film consisting of aluminum oxide and aluminum hydroxide by plasma treatment, heat treatment, anodization, moist heat treatment, etc. How to transmute.

Among these methods, the method using aluminum as a raw material is preferable because the film forming apparatus is relatively simple and the film forming speed is high.
Among these, a method in which an aluminum oxide film is formed by a reactive vapor deposition method and then transformed into a film made of aluminum oxide and aluminum hydroxide by post-treatment is more preferable.

A specific example of this method will be shown below.

The figure is a schematic diagram showing an example of a reactive vapor deposition method for forming an aluminum oxide film.

In the figure, from the unwinding shaft 2 installed in the vacuum container 1,
The plastic film 5 is sent out and the temperature is -30 to -5°C.
The film is wound onto a winding shaft 4 via a cooling drum 3 which is cooled to a temperature of 1. During this time, aluminum in the evaporator 6 connected to the high-frequency induction heating power source evaporates on the cooling drum.
A thin layer of aluminum oxide is formed on the plastic film substrate 5 by reaction with oxygen gas supplied from the oxygen cylinder 10 through the gas flow control 11 device 9 through the gas outlet 8 surrounded by the mask 7 . The pressure in the vacuum container is 1
X10' to 1X10-2 torr, the amount of oxygen gas supplied is
It is adjusted according to the amount of aluminum evaporated from the evaporator 6. The thickness of the aluminum oxide film is adjusted by the power supplied to the evaporator and the film running speed.

The aluminum oxide vapor deposited film thus formed can be transformed into a film composed of aluminum oxide and aluminum hydroxide by post-treatment. The conditions for this post-treatment include moisture, temperature, and time; for example, 60°C;
Store in a constant temperature and humidity layer at 80% RH for 24 hours, or store at 20°C and 60% RH for one week at 100°C.
A method of heat treatment for 30 minutes in a hot air dryer is selected.

The heat treatment conditions for forming aluminum hydroxide are appropriately selected in consideration of the required gas barrier properties and the heat resistance of the plastic film substrate used.

The thin layer of aluminum oxide and aluminum hydroxide thus formed has a structure in which the aluminum hydroxide seals the thin aluminum oxide layer, which tends to have a porous film structure. Therefore, it has particularly excellent water vapor barrier properties.

The packaging film of the present invention has heat sealability and abrasion resistance on the plastic film surface and/or the thin layer surface consisting of aluminum oxide and aluminum hydroxide before or after providing the thin layer consisting of aluminum oxide and aluminum hydroxide. Coating, extrusion lamination, or lamination with other films or letters, to give
Patterns and the like can be printed as appropriate.

The packaging film according to the present invention has high transparency and excellent oxygen gas barrier properties and water vapor barrier properties, so it can prevent the contents from deteriorating and can be used as a packaging material with good transparency for foods, electrical parts, etc. It can be used for packaging ali cloth products, plastic parts, etc.

This will be explained below using examples.

The following method was used to measure the characteristics in the present invention.

■ Oxygen permeability measurement device (manufactured by Modern Controls, 0X-TRANloo) in accordance with ASTM D-3985.
) under the conditions of 20° C. and 0% RH.

◎ Water vapor transmission rate Water vapor transmission rate measuring device (manufactured by Honeywell Co., Ltd., W825
Measurement was carried out using a mold) under the conditions of 40°C and 100% RH.

■ Light transmittance spectrophotometer (Hitachi, Ltd., self-recording spectrophotometer 323)
The spectral transmittance was measured using a mold), and the transmittance at a wavelength of 550 nm was defined as the light transmittance.

[Examples Examples 1 to 3 and Comparative Examples include axially stretched polyethylene terephthalate film (thickness 20
[mu]m> was formed into a roll having a width of 500 am and a length of 10,00 Qm, and was installed in the reactive vapor deposition apparatus shown in the figure. Purity 99.
A high frequency induction heating evaporator was filled with 98% aluminum and the vacuum vessel was evacuated to 1X 1Q' TOrr.

Next, the high-frequency induction heating evaporator is heated, and at the same time as aluminum vapor deposition begins, the film begins to run. Oxygen gas is supplied from the gas outlet by a gas flow control device, and the amount of oxygen gas supplied is adjusted while checking the pressure of the vacuum container and the light transmittance of the vapor-deposited film, and the pressure is 3.0X1Q-4RO.
Vapor deposition was carried out at RR to obtain an aluminum oxide vapor deposited film with a thickness of 500 mm.

Next, the plus deck film on which aluminum oxide was formed was stored at 40°C and 80% RH for one week, and then
Example 1 was heat treated for 30 minutes in a hot air dryer at 00°C. Example 2 was heat treated for 10 minutes. Example 3 was heat treated for 1 minute.

Comparative Example 1 is one that was not subjected to heat treatment.

ESCA (manufactured by VG Scientific, ESCAL
As a result of surface analysis using AB-5), the ratio (weight ratio) of aluminum oxide to aluminum hydroxide was 65:35 in Example 1, 70:30 in Example 2, and 9 in Example 3.
0:10. In Comparative Example 1, the ratio was 100:0.

Table 1 shows the gas barrier properties of each.

Examples 4 to 5, Comparative Example 2 Two-wheel stretched polyethylene terephthalate film (thickness 5
0 μm), a film made of aluminum oxide and aluminum hydroxide was sputtered using a high frequency magnetron sputtering device (manufactured by Nikkei Anelva). Sputtering targeted a 6-inch diameter sintered body made of a mixture of aluminum oxide and aluminum hydroxide (mixing ratio 60:40 (weight ratio)), and a mixed gas of Ar and oxygen (Ar:02=9).
5:5 (volume ratio)), and 1:2 high frequency power of 13.56 mZ was applied. By adjusting the sputtering time, the film thickness was set to 200 layers as Example 4, the film thickness was set as 600 layers as Example 5, and the base film not subjected to sputtering as Comparative Example 2.

In both Examples 4 and 5, the ratio of aluminum oxide to aluminum hydroxide was 6 as a result of surface analysis by ESCA.
The weight ratio was 0:40.

Table 1 shows the gas barrier properties of each.

[Effects of the Invention] The packaging film of the present invention has a thin layer made of aluminum oxide and aluminum hydroxide formed on a transparent plastic film base, so it is transparent and has excellent oxygen gas barrier properties and water vapor barrier properties. be able to.

[Brief explanation of drawings]

The figure shows an example of an apparatus for producing the packaging film of the present invention, and exemplifies a reactive vacuum deposition apparatus. 1: Vacuum container 2: Unwinding shaft 3: Cooling drum 4: Winding shaft 5 Niblast film 6: Evaporator 7: Mask 8: Gas outlet

Claims (1)

[Claims] A packaging film comprising a thin layer of aluminum oxide and aluminum hydroxide on a transparent plastic film substrate.