JPH10128901A - Wrapping film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the transparency and the gas barrier property so as to prevent damage in the post processing stage after printing or laminate processing by successively laminating a perfect oxide layer of aluminum oxide having excellent adherence with a substrate and a silicon oxide layer on the substrate comprising a transparent polymer film. SOLUTION: A wrapping film 11 is produced by successively laminating an aluminum oxide layer 13 and a silicon oxide layer 14 on a substrate comprising a transparent polymer film 12. Examples of the substrate comprising a transparent polymer film 12 include polyolefin, polystyrene, polyester, and the like, which can be used as an ordinary wrapping material. As the aluminum oxide layer 13, a perfect oxide of aluminum formed by a direct deposition method with Al2 O3 is preferable with respect to the transparency, the gas barrier property, and the adherence with the substrate. A5 to 100nm layer thickness is preferable. It is preferable that the ratio of oxygen and silicon in the silicon oxide layer 14 as a whole is (1.2-1.7):1. The layer thickness is preferably 5 to 40nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging film used in the field of packaging foods, pharmaceuticals, precision electronic parts and the like, and more particularly, to a film having excellent transparency and gas barrier properties, and further post-processing such as printing and laminating. Process, contents filling process,
The present invention relates to a packaging film excellent in practical use with little deterioration in gas barrier properties during a post-treatment process such as retort sterilization and a distribution process.

[0002]

2. Description of the Related Art Packaging films used in the field of packaging of foods, pharmaceuticals, precision electronic parts, etc. maintain taste and freshness by suppressing deterioration of contents, especially oxidation and deterioration of proteins and oils and fats in foods. In order to reduce the deterioration of the active ingredient in pharmaceutical products and to maintain the efficacy, and in precision electronic components to suppress corrosion of metal parts and prevent insulation failure, etc. ,water vapor,
In addition, it is necessary to prevent the influence of gas that alters the contents, and it is required to have a gas blocking property of blocking these gases.

For this purpose, a polymer film generally known to have relatively high gas barrier properties, such as polypropylene (KOP), polyethylene terephthalate (KPET) or ethylene vinyl alcohol copolymer (EVOH) coated with a vinylidene chloride resin, is used. Packaging film used as a barrier layer, or metal foil such as Al foil, or metal obtained by evaporating a metal such as Al on a suitable polymer film (even if it is a resin that does not have high gas barrier properties by itself) Packaging films using vapor deposited films as gas barrier layers have been commonly used.

However, the above-mentioned KOP, KPET, EV
Packaging films using OH are not only inferior in gas barrier properties than metal foils and metallized films, but are also more susceptible to temperature and humidity, and their changes may further deteriorate gas barrier properties. . Furthermore, packaging films using vinylidene chloride resin such as KOP or KPET are said to be one of the causes of acid rain because chlorine gas is generated when they are incinerated in disposal after use. Tend.

[0005] On the other hand, a packaging film using a metal foil or a metal-deposited film is less affected by temperature and humidity and has excellent gas barrier properties, but is opaque and cannot be confirmed through the contents. It has the drawback that it cannot be used as a heating packaging material by a microwave oven because it does not pass microwaves, and that the contents cannot be inspected by a metal detector.

Accordingly, as a packaging film which has overcome these disadvantages, silicon oxide (Japanese Patent Application Laid-Open No. 53-1295) has recently been proposed.
No. 3 publication) and aluminum oxide (Japanese Patent Publication No. 4-2038).
No. 3) has been developed, in which an inorganic polymer film is provided on a substrate made of a transparent polymer film by means such as vacuum evaporation, and a part of the film is commercially available.

[0007]

However, in the above-mentioned silicon oxide vapor-deposited film, the gas barrier properties and the degree of coloring change depending on the ratio of oxygen and silicon, and the following inconveniences have occurred. That is, when the composition ratio (molar ratio) of oxygen and silicon is greater than about 1.7, a nearly colorless and transparent film can be obtained, but the gas barrier property is deteriorated. On the contrary, when the composition ratio is smaller than about 1.7, the gas barrier property is improved. However, there was a problem that the coloration of light yellow became remarkable, and depending on the type of the contents, the contents seemed to be discolored.

[0008] The above-mentioned aluminum oxide deposited film has the following problems. The method of vapor-depositing an aluminum oxide film on a transparent polymer film was performed by direct vapor deposition using Al ₂ O _{3 or} by evaporating metal Al, and separately introduced into a vapor deposition apparatus, due to the difference in the substance used as the evaporation source. It is roughly classified into a reactive vapor deposition method in which an aluminum oxide film is obtained by reacting with an oxygen gas.

In the above direct vapor deposition method, an aluminum oxide film which is colorless and transparent, has good gas barrier properties, and has good adhesion to a substrate made of a transparent polymer film can be obtained.
There is a problem that it is difficult to obtain a practical evaporation rate because the vapor pressure of l ₂ O ₃ is low.

Further, the above-mentioned reactive vapor deposition method has a problem that it is difficult to achieve both transparency and gas barrier properties, and it is also difficult to obtain a film having good adhesion to a substrate. That is, in order to achieve both the transparency and the gas barrier property, it is necessary to uniformly distribute the Al vapor and the oxygen gas and react them without excess or deficiency. If the oxygen gas is insufficient with respect to the Al vapor, an incomplete reaction product of Al remains in the deposited film and causes coloring. If the amount is large, coloring of the deposited film itself cannot be ignored. Conversely, if the oxygen gas becomes excessive, an excess oxygen gas molecule is taken in and a vapor deposition film is formed, so that the denseness of the vapor deposition film is lowered and, as a result, a gas barrier having a sufficient gas barrier property is obtained. Disappears. In addition, the reactive evaporation method is considered to be caused by the fact that the temperature of the evaporation source is lower than the direct evaporation method, so that the energy of the evaporated particles is small, and the flight direction of the evaporated particles is not uniform due to collision with oxygen gas. The problem is that the adhesion to the base material is low.

Further, one of the reasons that the aluminum oxide film is a major obstacle to practical use of the aluminum oxide film, whether it is a direct evaporation method or a reactive evaporation method, is the brittleness of the aluminum oxide film. The aluminum oxide film is more brittle than the silicon oxide film, so the film is easily broken in the post-processing steps such as printing and laminating, the filling step of the contents, the post-processing step such as retort sterilization, and the distribution process. However, even if the gas barrier property is good, there is a major problem that the gas barrier property tends to be reduced in the subsequent steps.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks, and is practically colorless and transparent, has a sufficient gas barrier property, and has high practical utility which does not cause deterioration of the gas barrier property even in a later process. Provide a film.

[0013]

According to the present invention, there is provided a packaging film comprising at least one surface of a substrate made of a transparent polymer film and an inorganic compound film provided on at least one surface thereof. Wherein the layer in contact with the base material is aluminum oxide and the surface layer is silicon oxide. The invention according to claim 2, wherein the thickness of the aluminum oxide layer is in the range of 5 to 100 nm. The invention according to claim 3 is characterized in that the aluminum oxide layer is a complete oxide layer of aluminum formed by directly vapor-depositing Al ₂ O _3. is there.

The invention according to claim 4 is characterized in that the thickness of the silicon oxide layer is in the range of 5 to 40 nm, and the invention according to claim 5 is characterized in that the thickness of the silicon oxide layer is A packaging film, wherein the ratio of oxygen to silicon is in the range of 1.2 to 1.7: 1.

Next, the packaging film according to the present invention will be described in detail with reference to the drawings. 1 and 2 are cross-sectional views each showing a configuration example of a packaging film according to the present invention. That is, as shown in FIG. 1, the packaging film 11 of the present invention has a structure in which an aluminum oxide layer 13 and a silicon oxide layer 14 are sequentially laminated on a base material 12 made of a transparent polymer film, or as shown in FIG. As described above, a mixed layer 15 of aluminum oxide and silicon oxide is provided between the aluminum oxide layer 13 and the layer 14 made of silicon oxide.

The substrate 12 made of the transparent polymer referred to in the present invention
Means polyolefin (polyethylene, polypropylene, etc.), polystyrene,
Polyester (polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.),
Polyamide (nylon-6, nylon-66, etc.), polycarbonate, polyvinyl chloride, polyvinylidene chloride,
It is a fluororesin (polytetrafluoroethylene or the like), a polyimide or the like, or a copolymer of these polymers.

Further, these polymers may contain known additives such as antistatic agents, ultraviolet absorbers, plasticizers, lubricants, coloring agents, antioxidants, antifogging agents, and the like. .

Further, if necessary, the surface of these polymer substrates may be subjected to corona treatment, low-temperature plasma treatment, chemical treatment,
It may have been subjected to a solvent treatment or the like.

Aluminum oxide layer 1 provided on the substrate
3 is preferably made of a complete aluminum oxide formed by a direct evaporation method using Al ₂ O ₃ as an evaporation material from the viewpoints of transparency, gas barrier 0, and adhesion to a substrate as described above. However, impurities that do not impair the transparency, gas barrier properties, and adhesion to the substrate may be contained therein.

The thickness of the aluminum oxide layer 13 is preferably in the range of 5 to 100 nm. 5
If the thickness is less than 100 nm, aluminum oxide is formed into an island shape instead of a film shape, and gas barrier properties and adhesion may be insufficient. Conversely, if the thickness is more than 100 nm, internal strain in the film may cause a problem. Is likely to be peeled off from the base material or the film may be broken.

Next, on the aluminum oxide layer 13,
The silicon oxide layer 14 will be described. What is silicon oxide?
Various compounds of oxygen and silicon (SiO, Si_Two O_Three , S
i_Three O _Four , SiO_Two One or two)
As described above, in the present invention, oxygen
And the ratio of silicon to silicon is in the range of 1.2 to 1.7: 1,
And the thickness of the film must be in the range of 5 to 40 nm.
Conditions.

This condition is based on the following findings. As the composition ratio of oxygen and silicon in silicon oxide approaches the ratio of silicon dioxide (SiO ₂ ), which is a stoichiometric composition, the structure of silicon oxide is such that oxygen and silicon alternate (ie, −Si) as shown in FIG. —O—Si—O—) It is presumed that they are bonded in a ring shape, and that dangling bonds are also reduced. For this reason, light absorption due to the dangling bond is small and it is difficult to be colored, but it is considered that the gas barrier property is reduced due to the presence of the space in the ring-shaped structure.

On the other hand, as the composition ratio of oxygen and silicon in silicon oxide deviates from that of silicon dioxide (SiO ₂ ), which is a stoichiometric composition, (ie, the composition ratio becomes smaller than 1.7), As shown in FIG. 4, it is presumed that, as shown in FIG. 4, some oxygen atoms are missing in the ring-shaped structure, the number of dangling bonds is increased, and the ring shape is reduced. For this reason, it is considered that the light absorption due to the dangling bond is increased and the color is easily colored, and the ring shape is reduced, so that the space is narrowed and the gas barrier property is improved.

Therefore, in order to achieve both transparency and gas barrier properties, it is important to balance the ratio between oxygen and silicon and the thickness of the film. That is, when the ratio of oxygen to silicon is less than 1.2, coloring is conspicuous even when the film thickness is 5 nm, which is the minimum thickness at which the silicon oxide layer becomes a film, and when the thickness is more than 40 nm, sufficient gas blocking performance is obtained. Even if the maximum ratio obtained is 1.7, coloring is conspicuous.

Means for providing this silicon oxide layer on a transparent polymer film substrate include a conventional PVD method such as vacuum deposition, sputtering and ion plating, and a plasma activated chemical vapor deposition method (hereinafter abbreviated as PECVD). Is used.

The ratio of oxygen to silicon in silicon oxide should be within the range of 1.2 to 1.7: 1 by appropriately adjusting the composition of the vapor deposition raw material and the gas composition and gas amount in the vapor deposition apparatus. Is possible.

Further, in the present invention, a mixture layer of aluminum oxide and silicon oxide may be present between the layer made of aluminum oxide and the layer made of silicon oxide.
However, in this case, it is natural that the thickness of the mixed layer is required to be a level that does not adversely affect the performance such as the overall coloring condition and gas barrier properties.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 5 is an example of a structural explanatory view of an apparatus for producing a packaging film according to the present invention.

That is, in this device, the housing 7
Is exhausted and maintained at 10 ^-3 to 10 ^-6 Torr by an exhaust device (not shown) connected to an exhaust port.

The substrate 1 made of a transparent polymer is in the form of a strip, and is unwound from an unwinding roll 31 and a guide roll 32.
After passing through the cooling roll 33, it travels, passes through the guide roll 32 and the like, and is taken up by the take-up roll 34.

A crucible 41 containing a vapor deposition material 21 (Al ₂ O ₃ ), a crucible 42 containing a vapor deposition material 22 (eg, SiO), and a housing 7 An electron gun 5 serving as a heating source connected to a power supply (not shown) arranged outside the camera is provided. Also,
In the vicinity of the crucibles 41 and 42, an electromagnetic coil 8 for bending an electron beam emitted from the electron gun 5 and irradiating the electron beams on the vapor deposition materials 21 and 22 is arranged.

In order to manufacture the packaging film of the present invention using this apparatus, first, the inside of the housing 7 is evacuated to a vacuum state, and then the substrate 1 made of a transparent polymer film is run at a predetermined speed. Meanwhile, the vapor deposition materials 21 and 22 are heated and vaporized, and are sequentially deposited on the surface of the substrate 1. When such an apparatus is used, a packaging film having a structure as shown in FIG. 2 is obtained, but the thickness of each layer is determined by the output of the electron gun (the output to the crucible 21 and the output to the crucible 22). The output of the substrate 1 is independently variable) and can be appropriately adjusted by arbitrarily changing the traveling speed of the substrate 1.

Further, in order to obtain a packaging film having a structure as shown in FIG. 1, it can be manufactured by using an apparatus having the structure shown in FIGS.

That is, in FIG. 6, the partition plate 9 is provided below the cooling roll 33 in the apparatus of FIG. 5, and in FIG. 7, an aluminum oxide layer is formed by vapor deposition and then deposited in the crucible 4. Replace the material 2 and re-open the housing 7
The inside is evacuated to deposit a silicon oxide layer.

[0035]

Embodiments of the present invention will be described below in detail. [Embodiment 1] The inside of the device housing 7 is 1 × 10 ^-5 To
After evacuation to rr, commercially available alumina (Al ₂ O ₃ : purity 99.5%) and silicon monoxide (SiO: purity 99%) were used as vapor deposition materials, respectively, at about 10 nm / s and about 30 nm.
/ N on a single side of a 12 μm thick polyethylene terephthalate (PET) film at an evaporation rate of
m, and deposited to a thickness of about 30 nm.

When the composition of these vapor deposited layers was analyzed by XPS (JPS-90SXV manufactured by JEOL Ltd.), the aluminum oxide layer was composed of complete Al ₂ O ₃ and the ratio of oxygen to silicon in the silicon oxide layer was about 1. 4: 1.

Next, on the vapor deposition layer of this vapor deposition film, about 2
A non-stretched polypropylene (CPP) having a thickness of 60 μm is dry-laminated through a polyester / urethane adhesive of g / m ² to form a laminated film, and the adhesion is evaluated by measuring and comparing the laminating strength. did.

As the gas barrier properties, the oxygen permeability and the water vapor permeability were measured for the films before and after lamination, and the optical characteristics were compared by measuring the light transmittance and by visual evaluation.

The details of the apparatus used for these measurements and the measurement conditions are described below. (1) Oxygen permeability (unit: cc / m ² / day) Using an oxygen permeability measuring device (trade name “MOCONOXTRAN 10 / 50A” manufactured by Modern Control Co., Ltd.)
The measurement was performed in an atmosphere of 25 ° C.-100% RH. (2) Water vapor transmission rate (unit: g / m ² / day) Measured under an atmosphere of 40 ° C. and 90% RH using a water vapor transmission rate measuring apparatus (trade name “MOCON PE1MATRAN W6” manufactured by Modern Control Co., Ltd.). did. (3) Light transmittance (unit:%) Spectrophotometer (trade name “UV-310 manufactured by Shimadzu Corporation”)
0 ”), the light transmittance at a wavelength of 350 nm was measured. (4) Laminate strength tensile tester (trade name “SS-
207-EP ") and a pulling speed of 300 mm / mi.
n, and the tensile angle was measured at 180 degrees.

The results of these measurements are summarized in Table 1.

[0041]

[Table 1]

[Examples 2 to 4, Comparative Example 1] Deposition was performed in the same manner as in Example 1 except that the thicknesses of the aluminum oxide layer and the silicon oxide layer were variously changed. went. Table 1 summarizes the conditions and the evaluation results. Table 1 summarizes the conditions and the evaluation results.

[Comparative Examples 2 and 3] Using the apparatus shown in FIG. 7, the same evaluation as in Example 1 was performed on a vapor-deposited film on which only an aluminum oxide layer and only a silicon oxide layer were formed. The results are also shown in Table 1.

Comparative Example 4 Using the apparatus shown in FIG.
The deposition was performed in the same manner as in Example 1 except that silicon oxide was deposited using silicon dioxide (SiO ₂ : purity 99%), and the same evaluation as in Example 1 was performed. The results are also shown in Table 1.

Comparative Example 5 Using the apparatus shown in FIG.
Example 1 was repeated except that silicon oxide was deposited using a deposition material in which silicon dioxide (SiO ₂ : purity 99%) and silicon (Si: purity 99.5%) were mixed at a molar ratio of 1: 1. Vapor deposition was performed in the same manner, and the same evaluation as in Example 1 was performed. The results are also shown in Table 1.

[0046]

As described above, the packaging film of the present invention has a thickness of 5 to 5 μm on a substrate made of a transparent polymer film.
A complete oxide layer of aluminum oxide having excellent adhesion to a substrate having a thickness of 100 nm, and a ratio of oxygen to silicon of 1.2 to 1.2.
By having a structure in which silicon oxide layers each having a thickness of 5 to 40 nm within a range of 1.7: 1 are sequentially laminated, excellent transparency and gas barrier properties, and a post-processing step such as printing and laminating; An object of the present invention is to provide a packaging film excellent in practical use in which a gas barrier layer is not deteriorated due to breakage of a gas barrier layer during a filling step of contents, a post-treatment step such as retort sterilization, and a distribution process.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a packaging film of the present invention.

FIG. 2 is a partial cross-sectional view of a packaging film of the present invention having a different configuration from FIG.

FIG. 3 shows an example of the structure of silicon oxide which is a stoichiometric composition.

FIG. 4 shows an example of the structure of a silicon oxide that is not a stoichiometric composition.

FIG. 5 is a partial cross-sectional view of a vapor deposition apparatus used for manufacturing the packaging film of the present invention.

FIG. 6 is a partial cross-sectional view of a vapor deposition apparatus used for manufacturing the packaging film of the present invention.

FIG. 7 is a partial cross-sectional view of a vapor deposition apparatus used for manufacturing the packaging film of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Packaging film 12 Base material 13 Aluminum oxide layer 14 Silicon oxide layer 15 Mixed layer of aluminum oxide and silicon oxide 1 Base material 2,21,22 Deposition material 31 Unwind roll 32 Guide roll 33 Cooling roll 34 Take-up roll 4, 41, 42 crucible 5 electron gun 7 housing 8 electromagnetic coil 9 partition plate

Claims (5)

[Claims] 1. A packaging film comprising an inorganic compound film provided on at least one surface of a substrate made of a transparent polymer film, wherein the inorganic compound film comprises at least two layers, the layer in contact with the substrate is aluminum oxide, and the surface is A packaging film, wherein the layer is made of silicon oxide. 2. A method according to claim 1, wherein said aluminum oxide layer has a thickness of 5-10.
The packaging film according to claim 1, wherein the thickness is within a range of 0 nm. 3. The packaging film according to claim 1, wherein said aluminum oxide layer is a complete oxide layer of aluminum obtained by directly depositing and forming Al ₂ O ₃ . 4. The packaging film according to claim 1, wherein the thickness of said silicon oxide layer is in the range of 5 to 40 nm. 5. The packaging film according to claim 1, wherein the ratio of oxygen to silicon in the silicon oxide layer is in the range of 1.2 to 1.7: 1.