JPH05338073A - Laminated film - Google Patents

Abstract

PURPOSE:To improve a transparency, gas barrier properties, a practicability by taking such means as to laminate a polymer resin film on a transparent gas barrier film provided with an aluminum oxide film and specify the whole film thickness and aluminum metal component content of the aluminum oxide film, respectively. CONSTITUTION:On a transparent gas barrier film provided with an alunimum oxide film provided on at least one surface of a polymer resin film substrate, at least one polymer resin film layer is laminated. At this time, the whole film thickness of the aluminum oxide film is determined to be not less than 6nm. At least one incompletely oxidized film layer incorporating an aluminum metal component is provided only in the aluminum oxide film. The content of the aluminum metal component in the whole aluminum oxide film is determined to be within a range of 0.5-10%.nm. At the time of production, the polymer resin film 3 is supplied to a cooling drum 2 disposed above a vapor source 1, and an oxide film is vapor deposited on the film through an opening of a barrier plate 4.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a laminated film having excellent gas barrier properties and transparency.

[0002]

2. Description of the Related Art In order to preserve foods and drugs for a long period of time,
It is necessary to carry out packaging having excellent so-called gas barrier properties, which has an effect of blocking the invasion of oxygen and water vapor from the outside air that promotes decay and deterioration. In recent years, there has been an increasing tendency in particular for film packaging materials having excellent gas barrier properties, which are used for this purpose, to be required to have transparency so that the state of the contents can be confirmed.

It is well known in the art that a metal oxide formed on a polymer film substrate has excellent gas barrier properties and transparency. Among these, particularly those in which silicon oxide is formed on a polymer resin film are disclosed in JP-B-53-1.
Japanese Patent Publication No. 62-179935 discloses that aluminum oxide is formed on a polymer resin film according to Japanese Patent No. 2953.
It is known from the publication.

By the way, the silicon oxide thin film is, for example, German LEY.
B.T. G. Krug et al. Are Barrier P
ack Conference (London, Ma
y21 and 22, 1990) and the magazine "Convertec" 1990.6 30-36.
As shown in the page (by Keisuke Kaiho), 50n is required to secure high gas barrier properties (oxygen permeability ² cc / m ² · day or less, water vapor permeability 2 g / m ² · day or less).
A film thickness of about m is required. In addition, a complete oxide film of Si
Since the composition of O ₂ does not exhibit the gas barrier property, a thin film having a composition of oxygen deficiency, that is, a composition of SiO _x (X <2.0) is formed. So it's transparent,
Absorption on the short wavelength side becomes large and the vapor deposition film has a yellow coloration, and when food is put inside, it is difficult to understand the state of alteration, or it seems that alteration is occurring even if it is not altered. There is. In addition, when a thin base film is used due to its large thickness, curling is likely to occur, which causes poor handling properties, and if handled roughly, cracks will occur in the vapor deposition film and gas barrier properties will deteriorate. is there.

On the other hand, the aluminum oxide film is colorless and transparent,
A gas barrier property can be exhibited to some extent. However, the magazine “Japan Food Science” 1990.12
As described on pages 58 to 63 (written by Hideo Watanabe), it was impossible to develop a gas barrier property comparable to that of a silicon oxide thin film. As a similar application of an aluminum oxide film, Japanese Patent Application Laid-Open No. 62-220330 discloses a polymer for an incomplete aluminum oxide film containing 1 to 15% by weight of a metal component of aluminum as a packaging material for electronic materials. A film formed on a resin film substrate and having antistatic property and gas barrier property is disclosed. However, it is described that the light transmittance is considerably reduced by the presence of at least 1% by weight of aluminum metal in the entire film, and there is a problem in transparency. Further, since the film has antistatic property (that is, conductivity), it has a low microwave transmittance and cannot be heated when used as a packaging material and heated in a microwave oven while packaging the contents. was there.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems. That is, it is an object of the present invention to provide a film having high transparency and excellent gas barrier properties, and in which the drawbacks of the conventional transparent gas barrier film such as coloring and microwave oven heating property are eliminated. Furthermore, the present invention is flex resistance,
It is an object of the present invention to provide a film in which the practically important properties of a transparent gas barrier film such as boil resistance are remarkably improved.

[0007]

According to the present invention, at least one polymer resin film is laminated on a transparent gas barrier film having an aluminum oxide film formed on at least one surface of a polymer resin film substrate. A laminated film, wherein the total thickness of the aluminum oxide film is 6 nm or more, and at least one incomplete oxide layer containing a metal component of aluminum is present only inside the aluminum oxide film, The content of aluminum metal component in the entire aluminum oxide film is 0.5% ・ nm to 10% ・
It is a laminated film having a range of nm.

The material of the polymer resin film base material of the transparent gas barrier film used in the present invention is not particularly limited, but typical ones include polyolefins such as polyethylene and polypropylene, polyethylene terephthalate,
Polybutylene terephthalate, polyethylene-2,6-
Polyester such as naphthalate, polyamide such as nylon 6 and nylon 12, polyvinyl chloride, polyvinylidene chloride, ethylene vinyl acetate copolymer, polystyrene, polycarbonate, polyacrylonitrile, polysulfone, polyphenylene oxide, polyphenylene sulfide, aromatic polyamide, polyimide , Polyamideimide, cellulose, cellulose acetate, etc.,
Examples thereof include these copolymers and copolymers with other organic substances. In terms of transparency and gas barrier properties, polyester such as polyethylene terephthalate,
Polyolefins such as polyethylene and polypropylene are preferable, and polyethylene terephthalate type is more preferable.

In the case of a thermoplastic resin, these polymer resin films may be unstretched, uniaxially stretched or biaxially stretched, but are biaxially stretched from the viewpoint of dimensional stability, mechanical properties and gas barrier stability. Those that are preferred. In the polymer resin film substrate, known additives such as antistatic agents, antioxidants, lubricants, anti-coloring agents, ultraviolet absorbers, plasticizers, colorants, etc. may be used if they do not cause food hygiene problems. It may be added.

The polymer resin film is preferably transparent and has a light transmittance of preferably 40% or more, more preferably 60% or more, still more preferably 80% or more. In addition, prior to vapor deposition, known surface treatment on the film,
For example, corona discharge treatment, glow discharge treatment, or anchor coating treatment by coating may be performed.

Further, the surface of the polymer resin film used in the present invention for forming the aluminum oxide film is preferably smooth. The center line average roughness is preferably 0.5 μm or less, more preferably 0.2 μm or less, still more preferably 0.05 μm or less. The reason for this is that if there are large protrusions on the film surface, the gas barrier vapor deposition film will not be formed uniformly.

The thickness of the polymer resin film used in the present invention is not particularly limited, but is 5 μm as a packaging material.
The range of m to 500 μm is preferable.

In the laminated film of the present invention, the total thickness of the aluminum oxide film formed on the polymer resin film substrate must be 6 nm or more. Total film thickness is 6 nm
If it is less than this, the gas barrier property cannot be satisfied. The total thickness of the aluminum oxide film is preferably less than 50 nm. If the total film thickness is large, curling is likely to occur, which may cause problems such as a sharp decrease in gas barrier property during processing. From the viewpoint of productivity, the total film thickness is preferably small, and more preferably the total film thickness is less than 30 nm.

In the laminated film of the present invention, at least one incompletely oxidized layer containing the metal component of aluminum is present only inside the aluminum oxide film. It is difficult to obtain an excellent gas barrier property if the incompletely oxidized layer containing the metal component does not exist inside the aluminum oxide film and the entire aluminum oxide film is composed of the complete oxide film. On the other hand, when a metal component is found in the entire aluminum oxide film, that is, when the entire layer is composed of an incomplete oxide film, the light transmittance becomes low, which is not preferable.

Here, the presence or absence and the degree of the aluminum metal component contained in the aluminum oxide film are X-ray photoelectron spectroscopy (hereinafter referred to as XPS) which is an analysis method having a very high surface sensitivity.
I have to say. ) It can be identified by the Al2p spectrum by analysis. That is, the peak (Al (II
It can be seen that a metal component of aluminum is contained when it has an Al (0) peak indicating the presence of a metal component other than I)). Further, in order to confirm that the aluminum metal component is contained only in the aluminum oxide film, the XPS analysis is performed not only from the surface of the aluminum oxide film, but also the aluminum oxide film is gradually ion-etched from the surface. However, it is necessary to perform XPS analysis and follow the change in the Al2p spectrum (hereinafter referred to as depth profile) along the depth direction of the aluminum oxide film. That is, "the aluminum metal component is contained only inside the aluminum oxide film" means that the Al (0) peak is not recognized in the XPS analysis from the surface,
An Al (0) peak was observed in the middle of the depth profile, and Al near the interface with the polymer resin film substrate
(0) means that no peak is observed.

The content of the metal component of aluminum inside the aluminum oxide film is specified by the following definition.
That is, when the depth profile of the Al2p spectrum by the XPS analysis is taken, the interface between the aluminum oxide film surface and the polymer resin film substrate is Al as described above.
Although only (III) indicates a complete oxide film, a spectrum showing the presence of a metal component of Al (0) is obtained in addition to the spectrum of Al (III) inside. The spectrum was divided into peaks at a depth d (nm unit) from the surface, and the peak areas of Al (III) and Al (0) were converted into the relative numbers of the aluminum atoms belonging to each, and the values were respectively converted into N ₃ (d ), N ₀ (d), and the existence ratio M (d) of the metal component of aluminum in the depth (unit:%)
100 × N ₀ (d) / (N ₃ (d) + N ₀ (d))
It is defined by (unit%). Depth d (nm) from the surface on the horizontal axis
A unit), and a vertical axis is a graph in which the abundance ratio M (d) (% unit) of the metal component of aluminum at the depth is plotted. Here, if the integration of M (d) in the depth d direction (d = 0 to d = total thickness of aluminum oxide film) is taken, a value having a unit of% .nm is obtained. This value corresponds to the amount of aluminum metal present in the aluminum oxide film and is defined as the aluminum metal component content (% · nm). In the laminated film of the present invention, the value of the aluminum metal component content is 0.
It must be 5% · nm to 10% · nm. 0.5%
・ If it is less than nm, the gas barrier performance is insufficient and it is 10%.
・ If it exceeds nm, the light transmittance is lowered, and the gas barrier property after boil treatment is drastically lowered. In order to obtain a higher gas barrier property, 1% · nm to 10% · nm is more preferable.

Although at least one layer containing a metal component of aluminum is present inside the aluminum oxide film of the laminated film of the present invention, two or more layers may be present. The number of layers is M in a graph in which the horizontal axis represents the depth d (nm unit) from the surface and the vertical axis represents the abundance ratio M (d) (% unit) of the aluminum metal component at that depth.
It can be judged by the shape of the distribution of (d).

The transparent gas barrier film used in the present invention has an oxygen transmission rate of ² cc / m ² · day or less (more preferably 1 cc / m ² · day or less) and a water vapor transmission rate of 2 g / m ² · day or less ( More preferably 1 g / m ²
・ Day or less) is preferable.

The laminated film of the present invention is formed by laminating at least one polymer resin film on the above transparent gas barrier film. The material of the polymer resin film to be laminated is not particularly limited, but typical ones include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, nylon 6, nylon 12 and nylon 12. Such as polyamide, polyvinyl chloride, polyvinylidene chloride, ethylene vinyl acetate copolymer, polystyrene, polycarbonate, polyacrylonitrile, polysulfone, polyphenylene oxide, polyphenylene sulfide, aromatic polyamide, polyimide, polyamideimide, cellulose, cellulose acetate and the like and Examples thereof include copolymers thereof and copolymers with other organic substances. transparency,
Polyester such as polyethylene terephthalate, polyolefin such as polyethylene and polypropylene, nylon 6 in terms of bending resistance, heat resistance and pinhole resistance.
Polyamides such as

In the case of a thermoplastic resin, these polymer resin films may be unstretched, uniaxially stretched or biaxially stretched, but from the viewpoint of flex resistance and heat resistance, biaxially stretched films are preferable, On the other hand, from the viewpoint of heat sealability, an unstretched material is preferable. In the polymer resin film, known additives such as antistatic agents, antioxidants, lubricants, anti-coloring agents, ultraviolet absorbers, plasticizers, colorants, etc. are added to the polymer resin film if they do not pose a problem in food hygiene. May be.

The polymer resin film is preferably transparent and has a light transmittance of preferably 40% or more, more preferably 60% or more, still more preferably 80% or more.

The laminated film of the present invention has a total light transmittance of 40% or more (more preferably 60% or more, further preferably 80% or more) at a wavelength of 550 nm, and an oxygen transmittance of ² cc / m ² · day or less (more Preferably 1 cc /
m ² · day or less), and a water vapor transmission rate of 2 g / m ² ·
day or less (more preferably 1 g / m ² · day or less)
It is preferable that Such a characteristic is that the total thickness of the aluminum oxide film is 6 nm or more, at least one incomplete oxide layer containing the metal component of aluminum is present only inside the aluminum oxide film, and the entire aluminum oxide film is present. The content of aluminum metal component in the steel is 0.
In addition to the range of 5% · nm to 10% · nm, the material, thickness, and light transmittance of the polymer resin film base material of the aluminum oxide film and the polymer resin film to be laminated should be appropriately selected. Can be achieved by However, since the gas barrier property of the laminated film is mainly expressed by the aluminum oxide film, it is not necessary to use the gas barrier film as the polymer resin film substrate of the aluminum oxide film and the polymer resin film to be laminated.

The polymer resin film may be provided in at least one layer on at least one side of the above-mentioned transparent gas barrier film, and there is no particular limitation on the side on which it is provided and the number of layers, but from the viewpoint of boil resistance and retort resistance. The polymer resin film is preferably provided so as to cover the aluminum oxide film formed on the surface of the transparent gas barrier film. In the case of such a constitution, the total light transmittance and the oxygen transmittance after boiling the laminated film for 30 minutes in boiling water are 40% or more (more preferably 60% or more and further preferably 80% or more) and it is preferable to 2cc / m ² · day or less (more preferably 1cc / m ² · day or less).

At least one outermost layer of the laminated film of the present invention is preferably composed of a heat-sealable film. Here, the heat-sealing property means that the films are superposed and pressed with each other while being heated to adhere to each other.

The composition of the polymer resin film exhibiting such heat sealability (hereinafter sometimes referred to as sealant film) is polyethylene, polypropylene, ethylene / propylene copolymer, ethylene / vinyl acetate copolymer, Examples thereof include ethylene / methacrylic acid copolymers, ethylene / acrylic acid copolymers, olefinic ionomers, and copolyesters.
The sealant film may contain additives such as an antiblocking agent and a slip agent at a concentration such that they are usually added.

A printing layer other than the polymer resin film and a coating layer such as an adhesive may be provided on the surface of the laminated film of the present invention or between the laminated layers. However, a configuration in which an opaque layer such as aluminum foil or metal aluminum vapor deposition covers the entire surface and impairs transparency is not suitable for the purpose of the present invention. When a partially opaque layer such as a printing layer is formed, the total light transmittance described above is measured at the transparent portion.

Next, a method for producing the laminated film of the present invention will be described.

The method for forming an aluminum oxide film in the present invention is by reactive vapor deposition in an oxygen atmosphere. The oxygen atmosphere means an oxygen gas alone or an oxygen gas diluted with an inert gas and introduced into a vacuum vapor deposition machine in a required amount. The inert gas refers to a rare gas such as Ar or He, a nitrogen gas, or a mixed gas thereof. What is reactive vapor deposition? A method of evaporating aluminum from an evaporation source in such an oxygen atmosphere and causing an oxidation reaction near the polymer resin film base material to form aluminum oxide on the polymer resin film base material. Is. The evaporation source for this purpose includes, but is not particularly limited to, a resistance heating type boat type, a crucible type using radiation or high frequency heating, and an electron beam heating type.

In order to form the aluminum oxide film having the constitution of the present invention, the relationship between the beam intensity of aluminum vapor deposited on the polymer resin film substrate and the oxygen partial pressure in the vicinity of the polymer resin film substrate is important. Is.

FIG. 1 shows a general positional relationship between an evaporation source and a film when vapor deposition is continuously carried out on a film-shaped substrate. Cooling drum 2 arranged above evaporation source 1
Is rotated to supply the polymer resin film 3 to this drum. Generally, an adhesion-preventing plate 4 having an opening is provided directly above the evaporation source having the highest beam intensity of aluminum vapor from the evaporation source, and vapor deposition is performed on the polymer resin film substrate from this opening. When considering the opening positions 5, 6, and 7 when the opening is large, 6 has the highest beam intensity of aluminum vapor, and 5 and 7 have the weakest.

Here, only in the space above the deposition-inhibitory plate 4, aluminum can be completely oxidized with respect to the beam intensity of the aluminum vapor in the space which is uniform and in the vicinity of 5 and 7, but in the vicinity of 6 When an oxygen partial pressure that does not sufficiently oxidize aluminum is applied to the beam intensity of the vapor, a fully oxidized layer in which oxygen is sufficiently supplied is formed in the vicinity of 5 and 7, that is, at the beginning of vapor deposition and at the end of vapor deposition. In the central part of 6, an incomplete oxide layer with insufficient oxygen is formed. FIG. 2 illustrates the relationship between the aluminum vapor strength at positions 5, 6, and 7 and the oxygen partial pressure in this case. As is generally known, the vapor intensity in the direction of the angle θ from the normal to the evaporation source is proportional to cos ⁿ θ (n is generally a value of 2 to 4), so the aluminum vapor intensity is as shown in FIG. Take the distribution.

In the method of applying a uniform oxygen partial pressure to the entire space including the space below the deposition-inhibitory plate 4, that is, in the case where an oxygen atmosphere is uniformly introduced into the upper and lower portions of the deposition-inhibitory plate, the structure of the present invention is used. It becomes extremely difficult to obtain an aluminum oxide film having The reason for this is as follows. That is, as described above, when the oxygen partial pressure of the vapor deposition portion on the deposition preventive plate is made to be a target value, the oxygen partial pressure of the evaporation source portion simultaneously rises, and an oxide film is formed on the surface of the aluminum melt of the evaporation source. It is easy to be done. When an oxide film is formed on the surface of the aluminum melt, the evaporation rate of aluminum sharply decreases. Therefore, the aluminum vapor strength is reduced as a whole, and the degree of oxidation of the formed film is increased. At the same time, a decrease in the evaporation rate of aluminum causes a decrease in oxygen consumed in the formation of an aluminum oxide film and an increase in the oxygen partial pressure. As a result, it becomes difficult to stably form an aluminum oxide film having a layer containing an aluminum metal component inside.

When an oxidizing atmosphere is introduced from the vicinity of the opening position 10 as shown in FIG. 3, 5, 6, 7 as shown in FIG.
Since the oxygen partial pressure decreases in the direction of, the position where the oxygen-deficient layer is formed shifts to the 7 side. Therefore, a layer containing a metal component is formed relatively near the surface.
Further, it can be easily estimated that a layer containing a metal is formed in the center even when the oxygen atmosphere is introduced from both the vicinity of 5 and 7.

In any case, in order to obtain the transparent gas barrier film of the present invention, it is essential to introduce an oxygen atmosphere near the vapor deposition portion (near the polymer resin film substrate). Surrounding the region where oxygen is consumed as shown in FIG. 3 accurately controls the relationship between the beam intensity of the aluminum vapor and the oxygen partial pressure described above, efficiently uses oxygen, and uses it in an exhaust pump more than necessary. It is also important not to load.

Incidentally, the conventionally known Japanese Patent Laid-Open No. 62-22033.
In Japanese Unexamined Patent Application Publication No. 0-163, an aluminum oxide film containing 1 to 15% by weight of metallic aluminum is X on the vapor deposition surface.
Since 1% by weight or more of the metal component of aluminum is recognized by PS analysis, it is essentially different from the constitution of the present invention in which at least the metal component is not recognized on the surface.

As a means for laminating at least one layer of the polymer resin film on the transparent gas barrier film having the aluminum oxide film formed on at least one surface of the polymer resin film substrate thus obtained, any known method can be used. Can be applied. For example, a method of laminating a pre-formed polymer resin film with an adhesive (dry lamination), melting the polymer resin with a melt extruder, and extruding the melted polymer resin into a film shape. A coating method (extrusion lamination) or the like can be applied. In either case of dry laminating or extrusion laminating, an anchor coat layer can be provided on the surface to be laminated in order to increase the adhesive strength after laminating, prior to laminating or applying an adhesive.

When two or more layers of polymer resin film are laminated on the film, the above method may be repeated a plurality of times,
They can be formed by combining them, or can be formed by laminating a film formed in advance with a laminated film composed of two or more layers.

[0038]

[Characteristic Measuring Method and Effect Evaluation Method] The characteristic values of the present invention are determined by the following measuring methods.

(1) Total film thickness The total film thickness was determined by the peak intensity of aluminum by fluorescent X-ray spectroscopy calibrated by cross-sectional observation with a transmission electron microscope. X-ray fluorescence spectroscopy was performed with SEA2001 manufactured by Seiko Denshi. Some of the samples subjected to the fluorescent X-ray spectroscopy were taken with a transmission electron microscope (JEM-1 manufactured by JEOL Ltd.).
The cross section of the vapor-deposited film was cut out and observed by the ultra-thin section method with 200 EX), and it was confirmed that the aluminum peak intensity of the fluorescent X-ray and the actual film thickness are in a good proportional relationship.

(2) Content of aluminum metal component Using an X-ray photoelectron spectroscope (SSX-100 manufactured by SSI), an X-ray source AlKα, an X-ray output of 10 kV-10 mA, and an escape angle of photoelectrons with respect to a normal line of the sample surface. Was measured at an angle of 55 degrees. Etching for depth profile measurement was performed using Ar ions at an acceleration voltage of 3 kV and a sample current of 10.3 μA. The calculation method of the content is as described above.

(3) Water Vapor Transmission Rate Water vapor transmission rate measuring device (W82, manufactured by Honeywell Co., Ltd.)
5) was used under the conditions of 40 ° C. and 100% RH.

(4) Oxygen permeability According to ASTM D-3985, the oxygen permeability was measured under the conditions of 20 ° C. and 0% RH by using an oxygen permeability measuring device (OX-TRAN100 manufactured by Modern Control Co.).

(5) Total light transmittance Spectrophotometer (Hitachi, Ltd., autograph spectrophotometer 323)
Type) to measure the total light transmittance at 550 nm.

[0044]

EXAMPLES The present invention will be described with reference to examples.

Examples 1 to 5 and Comparative Examples 1 to 2 Samples were prepared with the structure of the vapor deposition portion shown in FIG. The evaporation source is a system by electron beam heating, and 99.99% aluminum metal was loaded into an alumina crucible for vapor deposition. The film is a polyethylene terephthalate (hereinafter referred to as PET) film "Lumirror" P6 manufactured by Toray Industries, Inc.
0 (12 μm) was used. The film is fed from the unwinding roll in the form of a roll onto the cooling drum, and vapor deposition is performed directly above the evaporation source. As the oxygen atmosphere, 100% oxygen was introduced from the unwinding side. The cooling drum was cooled to about 20 ° C. with cold water.
The vapor deposition procedure is as follows. The film and aluminum for vapor deposition are set in a continuous vapor deposition machine, and vacuum exhaust is performed. When the ultimate pressure becomes 5 × 10 ⁻⁴ Torr or less, the film is run, and electric power is applied to the electron beam evaporation source to start aluminum vapor deposition. An in-line light transmittance meter and a resistivity meter are used to adjust the electric power of the evaporation source so as to obtain a target evaporation rate, and then oxygen gas is introduced through a mass flow controller. Set the film traveling speed to a low speed (for example, 1 m / min) and confirm that the light transmittance monitored in-line increases as oxygen is introduced. Adjust. A transparent gas barrier film was produced by increasing the film traveling speed so as to obtain a desired total thickness. All these samples are X
It was confirmed from the depth profile of PS analysis that a complete oxide film was formed at the interface between the surface of the aluminum oxide film and the PET film.

The transparent gas barrier film thus obtained and an unstretched polypropylene film were laminated by the following method. The polypropylene (PP) film used is "Trephan NO" manufactured by Toray Synthetic Film Co., Ltd. and has a thickness of 50 μm. Using a type 10 meta bar on a PP film, polyester adhesive "Adcoat AD-578A" 10 g and "Adcoat AD-578B" 1.4 g and ethyl acetate: butyl acetate (1: 1) 23.7 g manufactured by Toyo Morton Co., Ltd. Coating solution and dried in an oven at 80 ° C. for 1 minute. The vapor deposition surface of the transparent gas barrier film and the PP film coating surface are aligned, and the roll temperature is 80 ° C. and the linear pressure is 13 N / cm, 1 m / mi.
Dry lamination was performed with n to obtain a composite film.

In Table 1, the composite films thus prepared were tested in Examples 1 to 5 and Comparative Examples 1 to 2 in the initial and in boiling water.
The gas barrier properties after boil treatment for 0 minutes and the characteristics of the original PET film were summarized.

[0048]

[Table 1] Although the total light transmittance is high in both Examples and Comparative Examples, if the total film thickness is 6 nm or less, the gas barrier property is not sufficient both after lamination and after boiling. In addition, these laminated films can be bonded together by heat-sealing unstretched PP films together at 150 ° C. for 1 second.

Examples 6 to 10 and Comparative Examples 3 to 7 Table 2 shows Examples and Comparative Examples when the content of the metal component of aluminum was changed. Similarly, all samples are XPS
Due to the depth profile of the analysis, the surface of the aluminum oxide film is a complete oxide film.

[0050]

[Table 2] When the content of aluminum metal in the layer containing aluminum metal is extremely small in XPS analysis or when no aluminum metal is observed, the total light transmittance is very high and transparent regardless of the size of the total film thickness. The gas barrier property is not sufficient. Further, as shown in Comparative Examples 6 and 7, when the aluminum metal content exceeds 10% · nm, the gas barrier property after lamination is good but the total light transmittance sharply decreases regardless of the total film thickness. However, brown coloring becomes remarkable, which is not preferable. Further, if the aluminum metal content is large, the gas barrier property is rapidly lowered after boiling. It is considered that this is because when the aluminum metal content is high, the metal becomes hydroxide due to boiling and becomes bulky and disturbs the structure of the deposited film.

Examples 11 and 12 Polyethylene was extruded on the vapor deposition surface at a temperature of 320 ° C. for 30 hours.
Extrusion lamination with a thickness of μm was performed without anchor coating. This laminated film is referred to as Example 11. Further, a 20 μm thick nylon film manufactured by Toray Synthetic Film was dry laminated on the side opposite to the vapor deposition surface in the same manner as described above to obtain Example 12. The results are shown in Table 3.

[0052]

[Table 3]

[0053]

EFFECTS OF THE INVENTION The laminated film of the present invention has the features of high light transmittance and high gas barrier property against oxygen and water vapor due to the above constitution. In addition, there is no yellowish coloring, and it has practically sufficient processing suitability. In addition, the laminated film in which the aluminum oxide film is covered with the polymer resin film layer does not easily change the gas barrier property due to treatment such as retort or boil, and also has the gas barrier property due to physical friction, contact with acid or alkali, etc. It has the characteristic of being difficult to change.

The laminated film of the present invention can be widely used as a packaging material for foods and medicines that need to be stored for a long period of time. For example, it can be applied to packaging forms such as so-called retort pouches and standing pouches that can be stored for a long time by sterilizing food with a retort or boil, or use a thick laminated film to form a transparent box-shaped container having gas barrier properties. You can also

Since the laminated film of the present invention has a high light transmittance, it can meet the demand for confirming the state of the contents. Further, since the laminated film of the present invention has a high microwave transmittance, it can meet the demand that the contents are cooked in a microwave oven as it is in a packaged state.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a vapor deposition portion of a continuous vapor deposition machine that performs vapor deposition on a film-shaped substrate.

FIG. 2 shows the relationship between aluminum vapor strength and oxygen partial pressure in the case of FIG.

FIG. 3 is a vapor deposition part of a continuous vapor deposition machine for performing vapor deposition on a film-shaped substrate as in FIG. 1, but is a schematic diagram in the case where gas introduction for reactive vapor deposition is performed from the film unwinding side.

FIG. 4 shows the relationship between aluminum vapor strength and oxygen partial pressure in the case of FIG.

[Explanation of symbols]

 1: Evaporation source 2: Cooling drum 3: Film 4: Adhesion prevention plate 5: Evaporation position 6: Same as above 7: Same as above 8: Drum rotation direction 9: Aluminum vapor 10: Oxygen introduction route 11: Prevention when enclosing the evaporation portion Plate

Claims (4)

[Claims] 1. A laminated film in which at least one layer of a polymer resin film is laminated on a transparent gas barrier film having an aluminum oxide film formed on at least one surface of a polymer resin film substrate, said aluminum film comprising: The total thickness of the oxide film is 6 nm or more, and at least one incomplete oxide layer containing a metal component of aluminum is present only inside the aluminum oxide film. A laminated film having a component content in a range of 0.5% · nm to 10% · nm. 2. The total light transmittance at a wavelength of 550 nm is 40% or more and the oxygen transmittance is ² cc / m ² ·.
Water vapor permeability of 2g / m ² · day or less
The laminated film according to claim 1, wherein: 3. The total light transmittance and the oxygen transmittance after boiling treatment for 30 minutes in boiling water are 40% or more and 2 cc, respectively.
/ M < ² > * day or less, The laminated film of Claim 1 or Claim 2 characterized by the above-mentioned. 4. The laminated film according to claim 1, wherein at least one outermost layer of the laminated film is composed of a heat-sealing film.