JP7569946B1 - Barrier film and laminate using same - Google Patents

Abstract

[Problem] To provide a barrier film comprising a vapor-deposited film and a coating layer formed on an OPP film substrate, which can suppress deterioration of barrier properties and color unevenness after heat sterilization treatment, and a laminate using the same. [Solution] The barrier film comprises a biaxially oriented polypropylene substrate, a base layer, an aluminum oxide vapor-deposited film, and a coating layer having barrier properties, laminated in this order, the coating layer being a cured product of a resin composition containing an alkoxysilane and a hydroxyl-containing water-soluble resin, and the aluminum oxide vapor-deposited film has a peak top ratio P of 1.05 or more and less than 1.60 as determined by X-ray absorption fine structure analysis. P = (intensity peak top near 1572 eV) / (intensity peak top near 1566 eV) [Selected Figure] None

Description

The present invention relates to a barrier film and a laminate using the same.

Conventionally, laminated films having a film formed on a substrate such as a long film or sheet of plastic or the like have been used for various purposes. For example, a barrier laminated film has been developed that has a barrier layer made of a thin film such as aluminum oxide on a plastic film to provide a barrier function against oxygen and water vapor.

For example, Patent Document 1 discloses a method for producing a barrier film with an aluminum oxide thin film, which uses a plasma activated deposition method (a so-called plasma assisted deposition method) that generates high-density plasma in the space between an aluminum evaporation source and a polymer film, resulting in a gas barrier film with excellent transparency and gas barrier properties.

Patent Document 2 also describes that in a method for producing a gas barrier film having a vapor-deposited layer of aluminum oxide, the water vapor partial pressure is desirably 0.001 Pa or less, because water vapor reacts with aluminum to increase the degree of hydroxide.

On the other hand, in recent years, from the viewpoint of environmental consideration, mono-material packaging materials have been considered with the aim of improving the recyclability of packaging materials. For example, instead of the conventionally widely used polyester film (PET film), a polyolefin film such as a biaxially oriented polypropylene film (OPP film) is applied to the substrate, and a laminate using a polyolefin film such as a non-oriented polypropylene film (CPP film) as a sealant layer to be laminated with this is being considered as a mono-material packaging material.

For example, the following Patent Document 3 discloses a gas barrier laminate comprising a substrate layer containing a polyolefin resin, a barrier layer, and an overcoat layer containing a polyvinyl alcohol resin, the hardness of the surface of the overcoat layer being 1.5 GPa or less as measured by nanoindentation. In this way, a laminate comprising a barrier film in which a biaxially oriented polypropylene substrate, an inorganic oxide vapor deposition film, and a coating layer having barrier properties are laminated in this order, and a sealant layer, is known as a polyolefin-based mono-material packaging material.

JP 2017-177343 A JP 2022-052319 A WO2022/085586 International Publication

In Patent Document 1, the reactivity between oxygen and aluminum is increased by plasma assist during deposition, and the transparency and barrier properties are improved. However, there is a problem that color unevenness is easily generated in the barrier film and is easily noticeable. Regardless of whether plasma assist is used or not, when performing reactive deposition, the transmittance after deposition is usually measured and feedback is applied to the amount of evaporated aluminum or the amount of introduced oxygen to maintain the transmittance within a certain range and maintain a uniform appearance. However, in the case of high-speed production at several hundred meters per minute, this feedback may not be able to keep up, and if this causes the transmittance to fluctuate and the film is formed, color unevenness occurs, and when viewed from the end face of the barrier film roll, it has a Baumkuchen-like appearance. This appearance makes it suspect that the quality is not uniform, which becomes a problem. When a film is formed in a state of high transparency and barrier properties by plasma assist, there is a problem that color unevenness is noticeable and it is difficult to reduce color unevenness after production.

Also, as described in Patent Document 2, in the aluminum oxide deposition process, it is common to reduce the moisture content in the deposition chamber using, for example, a cold trap or a cryopump.

On the other hand, when a laminate made of polyolefin-based mono-material packaging material is applied to a heat sterilization process such as boiling or retort processing, the OPP film is inferior in heat resistance and strength to the PET film. For this reason, the barrier properties of the OPP film after heat sterilization processing are significantly reduced compared to the PET film.

In this regard, in conventional barrier films, there has been insufficient research into the deposition film and coating layer suitable for the OPP film used as the deposition substrate, and further research is needed into the deposition film and coating layer that can withstand heat sterilization treatment, particularly when used as a laminate.

Patent Document 3 also specifies the composite elastic modulus and hardness of the coating layer, but the issue is the "processing suitability" of the barrier film. For this reason, Patent Document 3 only specifies the composite elastic modulus and hardness of the coating layer "before heat sterilization treatment," and makes no mention of the heat sterilization treatment or the barrier properties thereafter.

The inventors' investigations have revealed that the composite elastic modulus and hardness of the coating layer vary before and after lamination and depending on whether or not heat sterilization is performed. For this reason, even if the composite elastic modulus and hardness of the coating layer "before heat sterilization" is specified as in Patent Document 3, it is not possible to predict the suppression of deterioration in barrier properties when the laminate is heat sterilized.

As a result of intensive research into solving the above problems, the inventors have discovered a vapor-deposited film and a coating layer formed on an OPP film substrate, which are barrier films constituting a laminate that is a polyolefin-based mono-material packaging material, and which reduce color unevenness in the barrier film and are suitable for heat sterilization treatment applications when formed into a laminate, thereby completing the present invention. Specifically, the present invention provides the following.

(1) A barrier film comprising a polypropylene substrate, a base layer, an aluminum oxide vapor deposition film, and a coating layer having barrier properties, laminated in this order,
the coating layer is a cured product of a resin composition containing an alkoxysilane and a hydroxyl group-containing water-soluble resin,
The aluminum oxide vapor-deposited film has a peak top ratio P, defined as follows, of 1.05 or more and less than 1.60 when X-ray absorption fine structure analysis is performed from the coating layer surface side of the barrier film.
P = (peak intensity top near 1572 eV) / (peak intensity top near 1566 eV)

(2) The barrier film according to (1), wherein the coating layer has a ratio of silicon atoms to carbon atoms (Si/C) measured by X-ray photoelectron spectroscopy (XPS) of 1.30 or more and 1.65 or less.

(3) The barrier film according to (1), wherein the undercoat layer is an anchor coat layer formed on the polypropylene substrate.

(4) The barrier film according to (1), wherein the undercoat layer is a surface resin layer containing a polyamide resin formed on the polypropylene substrate.

(5) The polypropylene base material has at least a first layer and a second layer as two surface layers, and the first layer is formed on the undercoat layer side,
the first layer comprises a copolymer of propylene and another monomer;
The undercoat layer is the anchor coat layer,
2. The barrier film according to claim 1, wherein the first layer of the polypropylene base material, the anchor coat layer, the aluminum oxide vapor deposition film, and the coating layer having barrier properties are laminated in this order.

(6) The polypropylene base material has at least a first layer and a second layer as two surface layers, and the first layer is formed on the undercoat layer side,
the first layer comprises modified polypropylene;
the undercoat layer is the surface resin layer containing the polyamide resin,
5. The barrier film according to claim 4, wherein the first layer of the polypropylene base material, the surface resin layer containing the polyamide resin, the aluminum oxide vapor-deposited film, and the coating layer having a barrier property are laminated in this order.

(7) The polypropylene base material has at least a first layer and a second layer as two surface layers, and the second layer is formed on the surface opposite to the undercoat layer side,
the second layer comprises a copolymer of propylene and another monomer;
2. The barrier film according to claim 1, wherein the first layer of the polypropylene base material, the undercoat layer, the aluminum oxide vapor-deposited film, and the coating layer having a barrier property are laminated in this order.

(8) A heat-sterilized laminate comprising the barrier film according to any one of (1) to (7) and a sealant layer, the laminate being used for a packaging bag for containing retort food or boiled food,
A laminate, wherein the coating layer of the laminate has a composite elastic modulus and an indentation hardness, as measured by a nanoindentation method from a cross-section of the coating layer, of which the composite elastic modulus is 5.0 GPa or more and 8.5 GPa or less, and the indentation hardness is 0.9 GPa or more and 1.7 GPa or less.

(9) A packaging product comprising the laminate described in (8).

The barrier film of the present invention has a vapor deposition film and a coating layer formed on an OPP film substrate, but it also reduces color unevenness and, in the laminate, can suppress the deterioration of the barrier properties after heat sterilization treatment.

FIG. 1 is a cross-sectional view showing an example of a barrier film according to an embodiment of the present invention. 1 is a diagram showing an example of a film forming apparatus according to an embodiment of the present invention; FIG. 2 is a cross-sectional view showing an example of a plasma pretreatment mechanism of a film forming apparatus. 2 is a plan view showing an example of an electrode unit and a magnetic field generating unit of a plasma pretreatment mechanism of a film forming apparatus. FIG. 2 is a cross-sectional view showing an example of an electrode unit and a magnetic field generating unit of a plasma pretreatment mechanism of a film forming apparatus. FIG. FIG. 2 is a cross-sectional view showing an example of a film formation mechanism of a film formation apparatus. FIG. 1 is a cross-sectional view showing an example of a laminate using the barrier film of the present invention. FIG. 2 is a cross-sectional view showing another example of a laminate using the barrier film of the present invention. FIG. 1 shows an XAFS spectrum of the barrier film of Example 2. FIG. 13 is a diagram showing the analysis results of the XAFS spectrum for the barrier film of Example 2. FIG. 13 is a diagram showing the analysis results of the XAFS spectrum for the barrier film of Example 3. FIG. 1 is a diagram showing the analysis results of an XAFS spectrum for the barrier film of Comparative Example 1. FIG. 13 is a diagram showing the analysis results of the XAFS spectrum for the barrier film of Comparative Example 2.

Specific embodiments of the present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be modified as appropriate within the scope of the object of the present invention. In addition, in this specification, the expression "X to Y" (X and Y are arbitrary numbers) means "X or more and Y or less."

Figure 1 is a cross-sectional view showing an example of a barrier film according to the present embodiment. A barrier film manufactured using the film-forming apparatus according to the present embodiment includes, for example, a substrate 100 corresponding to the biaxial polypropylene substrate of the present invention, a base layer 115, a vapor deposition film 120, and a coating layer 130, as in the barrier film 100A shown in Figure 1. In the example shown in Figure 1, the base layer 115 is located on one side of the substrate 100. In the example shown in Figure 1, the barrier film 100A is laminated in the order of the substrate 100, the base layer 115, the vapor deposition film 120, and the coating layer 130, and the coating layer 130 is located on the surface of the barrier film. The vapor deposition film 120 and the coating layer 130 constitute a barrier layer.

In this specification, "laminated in this order" means that the polypropylene base material, the undercoat layer, the aluminum oxide vapor deposition film, and the coating layer having barrier properties are laminated in this order, and further layers such as an anchor coat layer described below may be laminated between these layers.

The layers that make up the barrier film 100A are described below.

[Polypropylene base material]
The polypropylene base material 100 is a polypropylene base material that has been subjected to a biaxial stretching treatment. Hereinafter, except when referring to the stretching treatment, when the term "polypropylene base material" is used simply, it means a polypropylene base material that has been subjected to a biaxial stretching treatment.

The polypropylene base material is composed of at least polypropylene. The polypropylene may be any one of a propylene homopolymer, a propylene random copolymer, and a propylene block copolymer, or may be a mixture of two or more selected from these.

A propylene homopolymer is a polymer of propylene only. A propylene random copolymer is a random copolymer of propylene and an α-olefin other than propylene. A propylene block copolymer is a copolymer having a polymer block of propylene and a polymer block of at least an α-olefin other than propylene. The latter polymer block may be a polymer block of propylene and an α-olefin other than propylene.

Examples of α-olefins include α-olefins having 2 to 20 carbon atoms, specifically ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 3-methyl-1-butene, 4-methyl-1-pentene, and 6-methyl-1-heptene.

Among polypropylenes, it is preferable to use a random copolymer from the viewpoint of transparency. When emphasis is placed on the rigidity and heat resistance of the laminate, it is preferable to use a homopolymer. When emphasis is placed on the impact resistance of the laminate, it is preferable to use a block copolymer.

From the viewpoint of film-forming properties and processability, in one embodiment, the melt flow rate (MFR) of polypropylene may be 0.1 g/10 min or more and 50 g/10 min or less, or 0.3 g/10 min or more and 30 g/10 min or less. The MFR of polypropylene is measured in accordance with ASTM D1238 at a temperature of 230°C and a load of 2.16 kg.

As polypropylene, biomass-derived polypropylene or mechanically or chemically recycled polypropylene may be used.

The polypropylene content in the polypropylene base material is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more.

The polypropylene base material may contain a resin material other than polypropylene. Examples of the resin material include polyolefins such as polyethylene, (meth)acrylic resins, vinyl resins, cellulose resins, polyamides, polyesters, and ionomer resins.

The polypropylene base material may contain additives. Examples of additives include crosslinkers, antioxidants, antiblocking agents, slip agents, UV absorbers, light stabilizers, fillers, reinforcing agents, lubricants, antistatic agents, pigments, and modifying resins.

The polypropylene substrate is a substrate that has been subjected to a biaxial stretching process. This can improve, for example, the heat resistance, impact resistance, water resistance, and dimensional stability of the barrier substrate. A laminate including such a barrier substrate is suitable, for example, as a packaging material that is subjected to boiling or retort processing.

When stretching in the longitudinal direction (flow direction of the substrate, MD direction), the stretching ratio is preferably 2 to 15 times, more preferably 5 to 13 times. When stretching in the transverse direction (direction perpendicular to the MD direction, TD direction), the stretching ratio is preferably 2 to 15 times, more preferably 5 to 13 times. By setting the stretching ratio at 2 times or more, the strength and heat resistance of the polypropylene substrate can be further improved, and when the polypropylene substrate is used as the outermost layer, the printability of the polypropylene substrate can be improved. From the viewpoint of the breaking limit of the polypropylene substrate, the stretching ratio is preferably 15 times or less.

The thickness of the polypropylene substrate is preferably 10 μm to 100 μm, more preferably 10 μm to 50 μm, and even more preferably 15 μm to 25 μm. If the thickness is equal to or greater than the lower limit, the strength and heat resistance of the barrier substrate can be improved, for example. If the thickness is equal to or less than the upper limit, the processability of the barrier substrate can be improved, for example.

The polypropylene substrate may be a coextrusion stretched film. It can be produced by forming a laminated film using a conventionally known T-die method or inflation method, etc., and then stretching the laminated film. When forming the film using the inflation method, the laminated film may be stretched at the same time.

The polypropylene substrate may be surface-treated. This can improve the adhesion between the polypropylene substrate and other layers, for example. Surface treatment methods include physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using one or more gases selected from oxygen gas, argon gas, nitrogen gas, etc., and glow discharge treatment; and chemical treatments such as oxidation treatment using chemicals. In addition, an easy-adhesion layer may be provided on the surface of the polypropylene substrate.

When a polypropylene base material is used as the outermost layer of the laminate, a printed layer may be provided on the second layer. The image formed on the printed layer is not particularly limited, and examples include letters, patterns, symbols, and combinations of these. The printed layer can also be formed using ink derived from biomass. This can further reduce the environmental impact.

Methods for forming the printing layer include conventionally known printing methods such as gravure printing, offset printing, and flexographic printing. Among these, flexographic printing is preferred from the viewpoint of reducing the environmental impact.

The polypropylene base material is preferably transparent. Specifically, it is preferable that the total light transmittance measured based on JIS K 7361-1:1997 is high. Specifically, the total light transmittance is preferably 70% or more, more preferably 80% or more, and particularly preferably 90% or more.

It is preferable that the substrate 100 of the roll is moisture-conditioned in the process of forming the undercoat layer or in a moisture-conditioning process after the formation of the undercoat layer. This improves the barrier properties. It also prevents the substrate from breaking due to sticking when unrolled in the deposition process described below. One example of moisture-conditioning conditions is storage at a temperature of 22 to 30°C and a relative humidity of 40 to 65% RH for 1 to 7 days. Note that rewinding the roll before storage is also effective for moisture conditioning. In this case, it is preferable that the rewinding process is also performed under the above moisture-conditioning conditions.

The polypropylene substrate may be a multilayer film having at least a first layer and a second layer. The first layer is a layer on one side of the polypropylene substrate (the side on which a barrier layer such as a vapor deposition film is formed), and the second layer is a layer on the other side of the polypropylene substrate.

The first layer and the second layer may each be a propylene random copolymer, which is a random copolymer of propylene and an α-olefin other than propylene. By using the first layer and the second layer as a random copolymer, the adhesion between the layer and other layers in contact with the layer can be improved. Examples of α-olefins include ethylene, 1-butene, and 1-hexene.

The first layer may be modified polypropylene. When the undercoat layer described below is made of polyamide resin, the adhesion to the polyamide resin is improved.

The polypropylene substrate may include a third layer between the first layer and the second layer as an intermediate layer. The intermediate layer preferably contains a polypropylene homopolymer. The intermediate layer may have a single layer structure or a multilayer structure.

A specific example of a three-layer structure is a propylene random copolymer/propylene homopolymer/propylene random copolymer, in the order of first layer/third layer/second layer from the surface on which the vapor deposition film is formed. In this case, when the first layer is a propylene random copolymer and the undercoat layer described below is an anchor coat layer, adhesion to the anchor coat layer is improved. In addition, when the second layer is a propylene random copolymer, adhesion to the first adhesive layer 161 for laminating the sealant layer 150 is improved, for example, when forming the laminate shown in FIG. 7 described below.

Another example of a specific three-layer structure is modified polypropylene/propylene homopolymer/propylene random copolymer, in the order of first layer/third layer/second layer from the side on which the vapor-deposited film is formed. In this case, the first layer being modified polypropylene improves adhesion to the polyamide resin when the undercoat layer described below is made of polyamide resin. In addition, the third layer being a propylene random copolymer improves adhesion to the first adhesive layer 161 for laminating the sealant layer 150, for example, when forming the laminate shown in FIG. 7 described below.

[Base layer]
The base layer 150 is formed on the surface of the substrate 100 on which the deposition film 120 is formed. When the base layer is a surface resin layer made of a high melting point resin material described later, the deposition resistance is improved, promoting migration of the deposition material, and a deposition film consisting of a continuous layer that is dense, has few gaps, and is highly flexible is obtained. In addition, since the base layer is a high melting point resin material, the resistance to heat sterilization treatment is also improved. When the base layer is an anchor coat layer by coating described later, the surface of the substrate can be made smoother, promoting migration of the deposition material, increasing the adhesion strength between the polypropylene substrate and the deposition film, and a deposition film consisting of a continuous layer that is dense, has few gaps, and is highly flexible is obtained. As a result, high gas barrier properties are obtained, and breakage of the deposition film and coating layer due to deformation or bending of the film, and the resulting decrease in gas barrier properties can be suppressed. In addition, a barrier film having excellent heat resistance that can withstand heat sterilization treatment can be obtained.

(Surface resin layer)
The underlayer is preferably a surface resin layer. By providing a surface resin layer containing a resin material having a melting point of 180° C. or higher (hereinafter also referred to as a high melting point resin material) on a polypropylene base material, a dense vapor deposition film with few gaps can be formed on the surface resin layer, thereby improving the gas barrier property.

The melting point of the high melting point resin material is preferably 100°C or higher, more preferably 180°C or higher, and particularly preferably 200°C or higher. By setting the melting point of the high melting point material to 100°C or higher, when the second layer is a copolymer of propylene and other monomers or modified polypropylene, the second layer can be protected from the deposition material. By setting the melting point of the high melting point resin material to 180°C or higher, the density of the deposition film can be improved and the gas barrier property can be further improved. In addition, the resistance of the laminate to heat sterilization treatment can be further improved. From the viewpoint of film forming, the melting point of the high melting point resin material is preferably 265°C or lower, more preferably 260°C or lower, and even more preferably 250°C or lower. In this specification, the melting point can be measured in accordance with JIS K7121:2012 (Method for measuring transition temperature of plastics). Specifically, the melting point can be determined by measuring the DSC curve at a heating rate of 10°C/min using a differential scanning calorimetry (DSC) device.

The difference between the melting point of the high melting point resin material contained in the surface resin layer and the melting point of the polypropylene contained in the biaxially oriented polypropylene base material is preferably 20 to 100°C, and more preferably 20 to 70°C. When the melting point difference is 20°C or more, the density of the vapor deposition film can be further improved, and the gas barrier properties can be further improved. In addition, the resistance of the laminate to heat sterilization treatment can be further improved. When the melting point difference is 100°C or less, the film formability can be further improved.

The high melting point resin material preferably has a polar group. In the present invention, a polar group refers to a group containing one or more heteroatoms, and examples thereof include an ester group, an epoxy group, a hydroxyl group, an amino group, an amide group, a carboxyl group, a carbonyl group, a carboxylic anhydride group, a sulfone group, a thiol group, and a halogen group. Among these, from the viewpoint of the laminate strength of the packaging container, a hydroxyl group, an ester group, an amino group, an amide group, a carboxyl group, and a carbonyl group are preferred, and a hydroxyl group is more preferred.

The high melting point resin material can be used without any particular limitation as long as it has a melting point of 180°C or higher. Examples of high melting point resin materials include vinyl resins, polyamides, polyimides, polyesters, (meth)acrylic resins, cellulose resins, polyolefin resins, and ionomer resins.

In the present invention, the high melting point resin material has a melting point of 180°C or higher and is particularly preferably a resin material having a polar group, and is preferably an ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyester, or polyamide, and more preferably a polyamide such as nylon 6 (hereinafter "nylon" is a registered trademark), nylon 6,6, aromatic-containing nylon, or amorphous nylon. By using such a resin material, the gas barrier properties of the vapor deposition film formed on the surface resin layer can be effectively improved.

In one embodiment, the high melting point resin material is preferably polyamide. By using polyamide as the high melting point resin material, the deterioration of the gas barrier property can be suppressed even when the barrier laminate is heated. As the high melting point resin material, polyamide containing aromatics is preferable from the viewpoint of mechanical strength and gas barrier property. Polyamide containing aromatics can be combined with other materials and co-extrusion molded. An example of polyamide containing aromatics is nylon MXD6 manufactured by Mitsubishi Gas Chemical.

The thickness of the surface resin layer is preferably 0.1 μm or more and 5 μm or less, and more preferably 0.2 μm or more and 4 μm or less. By making the thickness of the surface resin layer 0.1 μm or more, the density of the vapor deposition film can be further improved, and the gas barrier properties can be further improved. By making the thickness 5 μm or less, the film-forming properties and processing suitability can be further improved.

The surface resin layer can be formed by melt extrusion. It may be extruded onto a biaxially oriented polypropylene film to form the polypropylene substrate of the present invention, or it may be coextruded with polypropylene in a multilayer structure and then stretched to form the polypropylene substrate of the present invention.

The undercoat layer may be an anchor coat layer. The anchor coat layer can be formed by coating a resin material having a polar group. As the resin material having a polar group, ethylene-vinyl alcohol copolymer (EVOH), polyvinyl alcohol (PVA), polyester, polyethyleneimine, hydroxyl group-containing (meth)acrylic resin, nylon 6, nylon 6,6, aromatic-containing nylon, amorphous nylon, polyurethane, etc. are preferred, and hydroxyl group-containing (meth)acrylic resin, ethylene-vinyl alcohol copolymer, and polyvinyl alcohol are more preferred. As the resin material having a polar group, from the viewpoint of gas barrier properties after heat sterilization treatment due to smoothness and high cohesive energy, (meth)acrylic resin containing urethane groups and hydroxyl groups is particularly preferred.

From the viewpoint of adhesion with the vapor deposition film, it is preferable to add a silane coupling agent to the anchor coat layer. As the silane coupling agent, the silane coupling agents described below can be used.

In the present invention, the anchor coat layer can be formed using a water-based emulsion or a solvent-based emulsion. Specific examples of water-based emulsions include polyamide-based emulsions, polyethylene-based emulsions, and polyurethane-based emulsions, while specific examples of solvent-based emulsions include polyester-based emulsions.

The thickness of the anchor coat layer is preferably 0.02 μm to 10 μm, more preferably 0.05 μm to 8 μm, even more preferably 0.1 μm to 5 μm, and even more preferably 0.2 μm to 3 μm. By making the thickness of the anchor coat layer 0.02 μm or more, the smoothness can be further improved, and the gas barrier properties after deposition can be further improved. By making the thickness of the anchor coat layer 10 μm or less, the processing suitability and productivity can be further improved.

The anchor coat layer may be formed by coating (applying, coating) on a biaxially oriented polypropylene substrate, or may be formed by coating on a polypropylene film and then biaxially oriented.

[Vapor-deposited film]
Next, the deposited film 120 will be described. The deposited film contains aluminum oxide, which is an inorganic oxide. In the deposited film, aluminum is present in a state in which at least a portion of it forms Al ₂ O _3. The deposited film may further contain metal oxides such as silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, magnesium oxide, titanium oxide, tin oxide, indium oxide, zinc oxide, and zirconium oxide, or nitrides and carbides of these metals.

The lower limit of the thickness of the deposited film is preferably 3 nm or more, and more preferably 5 nm or more. The upper limit is preferably 100 nm or less, more preferably 50 nm or less, and particularly preferably 15 nm or less.

In the present invention, the term "aluminum oxide vapor deposition film" means a vapor deposition film containing aluminum oxide as described above, and may contain aluminum oxide hydroxide AlO(OH) and aluminum hydroxide Al(OH _{)3 in} addition to aluminum oxide _Al2O3 . This will be explained in detail below.

(XAFS Spectral Analysis)
XAFS analysis is an X-ray absorption fine structure (XAFS) spectrum, in which X-rays are irradiated from the vapor deposition surface of the barrier film (the coating layer side if there is a coating layer) and the amount of absorbed X-rays is measured. Detailed measurement and analysis conditions are described in the examples.

In particular, XAFS spectrum analysis of soft X-rays using synchrotron radiation can provide bulk information on the entire deposited film, not just a portion of the surface side of the deposited film, and can provide information on the size of the hydroxyl groups in the aluminum oxide deposited film. Even if a coating layer or the like is present on the surface of the deposited film, it is possible to obtain information on the deposited film even with the coating layer present by irradiating the deposited film from the surface side of the coating layer through the coating layer.

Figure 9 shows an example of the results of XAFS measurement of the barrier film of Example 2 described below. Also, Figure 10 shows the peaks obtained by peak separation of the XAFS spectrum in Example 2. In Figures 9 and 10, the vertical axis is absorption intensity (a.u) and the horizontal axis is energy (eV). The peak top ratio P in the present invention is the ratio obtained from the respective peak tops after peak separation of the XAFS spectrum, for example as shown in Figure 10.

In the peak separation analysis in Figure 10, Experiment is the measured XAFS spectrum, Fit. Peak1 is the separated intensity peak of 1566 eV, Fit. Peak2 is the separated intensity peak of 1568 eV, and Fit. Peak3 is the separated intensity peak of 1572 eV. Fit. Base1 is the baseline of 1566 eV, and Fit. Base2 is the baseline of 1568 eV.

9 and 10, the XAFS spectrum has multiple peaks, specifically, peak P1 with a top near 1566 eV, peak P2 with a top near 1568 eV, and peak P3 with a top near 1572 eV. Note that "near 1566 eV" refers to 1565 eV or more and 1567 eV or less, "near 1568 eV" refers to more than 1567 eV and 1569 eV or less, and "near 1572 eV" refers to 1571 eV or more and 1573 eV or less.

Here, P1 is thought to be a peak derived from 4-coordinate aluminum oxide, P2 from 6-coordinate aluminum oxide, and P3 from 6-coordinate aluminum hydroxide and aluminum oxide hydroxide.

Amorphous aluminum oxide films are thought to have better flexibility than crystalline films, so amorphous films are preferable when used as barrier films. However, it has been difficult to determine whether a film is crystalline or amorphous using XRD, a conventional X-ray analysis, except in cases where clear crystalline peaks can be confirmed.

When checking the XAFS spectrum, crystalline aluminum oxide films in which P1 is detected include γ-Al ₂ O ₃ and θ-Al ₂ O ₃ , but the P1 peak is never relatively higher than the P2 peak. According to the examples of the present application described later, for example, as in Example 2 (see FIG. 10), it is clear that P1>P2, and it can be confirmed that an amorphous film is formed.

Furthermore, being amorphous is not enough to create a flexible aluminum oxide film; the introduction of hydroxyl groups is thought to be necessary. However, for example, with conventional depth analysis using TOF-SIMS, it is unclear whether the aluminum oxide film is being evaluated or whether residual moisture at the interface between the aluminum oxide film and the substrate is being detected, and sufficient depth resolution cannot be obtained in the aluminum oxide film when a coating layer is present, making it impossible to fully investigate the correlation between film formation conditions and film quality.

According to the present invention, by checking the XAFS spectrum and defining the peak top ratio P = P3 peak top / P1 peak top = (intensity peak top near 1572 eV) / (intensity peak top near 1566 eV), information regarding the amount of hydroxyl groups in the aluminum oxide vapor deposition film can also be obtained.

The inventors have found that a more effective method of reducing color unevenness is to form the aluminum oxide film in a state where there are many dangling bonds and where the water vapor barrier property is low, rather than forming the film in a state where the water vapor barrier property is high immediately after deposition, and then promote oxidation and hydroxylation (mainly hydroxylation) through aging to reduce the dangling bonds and develop water vapor barrier properties. For this reason, the inventors have confirmed the XAFS spectrum and investigated the correlation between the film formation conditions, including moisture during deposition and aging, and the film quality, leading to the completion of this invention.

The present invention has found that the color loss of the barrier film changes depending on the value of the peak top ratio P. Specifically, by setting the peak top ratio P to be 1.05 or more and 1.60 or less, it is possible to improve the barrier properties after heat sterilization treatment and improve the color unevenness of the barrier film at the same time. The lower limit of the peak top ratio P is preferably 1.10 or more, more preferably 1.20 or more. The upper limit of the peak top ratio P is preferably 1.50 or less.

If the peak top ratio P is less than 1.05, any color unevenness that occurs immediately after deposition is noticeable due to the high oxidation film, and the high barrier properties make it difficult for the color to fade. Note that "color fading" refers to an improvement in transparency (transmittance) or a fading in color due to changes over time after deposition. This transparency or color affects the appearance of the end faces (side faces) in the rolled state. Details will be explained in the evaluation of "color unevenness" in the examples. If the peak top ratio P exceeds 1.60 after performing a high-temperature, high-humidity moist heat treatment, too many hydroxyl groups are introduced, reducing the initial barrier properties, especially the water vapor barrier properties.

The peak-top ratio P of the barrier film can be adjusted by controlling the combination of moisture conditioning of the polypropylene substrate including the underlayer, plasma pretreatment, plasma assisted treatment during deposition, aging treatment after the film formation process, and aging treatment after the coating layer formation process. In particular, not using a cold trap in the film formation process can improve the barrier properties and reduce color unevenness in the barrier film. These results will be described in detail in the manufacturing method explanation and examples below.

[Coating layer]
The coating layer 130 formed on the deposited film 120 is a coating layer (barrier coat layer) that protects the deposited film mechanically and chemically and improves the barrier performance.

The coating layer is formed by applying a barrier coating agent onto the vapor deposition film and then solidifying it. The barrier coating agent is composed of a metal alkoxide, a water-soluble polymer, a silane coupling agent (which is added as needed), a sol-gel catalyst, an acid, etc.

The metal alkoxide is at least one type of metal alkoxide represented by the general formula _R1nM ( ^OR2 ) _m (wherein, _R1 and _R2 represent an organic group having 1 to 8 carbon atoms, M represents a metal atom, n represents an integer of 0 or more, m represents an integer of 1 or more, and n+m represents the atomic valence of M). Examples of the metal atom represented by M in the metal alkoxide include silicon, zirconium, titanium, aluminum, and others. For example, it is preferable to use an alkoxysilane in which M is Si.

The above alkoxysilane is, for example, one represented by the general formula Si(ORa) ₄ (wherein Ra represents a lower alkyl group). In the above, Ra may be a methyl group, an ethyl group, an n-propyl group, an n-butyl group, or the like. Specific examples of the above alkoxysilane include tetramethoxysilane Si(OCH ₃ ) ₄ , tetraethoxysilane Si(OC ₂ H ₅ ) ₄ , tetrapropoxysilane Si(OC ₃ H ₇ ) 4 , tetrabutoxysilane Si(OC ₄ H ₉ ) ₄ , and the like. The above alkoxides may be used in combination of two or more kinds.

As the silane coupling agent, those having reactive groups such as vinyl groups, epoxy groups, methacryl groups, and amino groups can be used. In particular, organoalkoxysilanes having epoxy groups are suitable, and for example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropyldimethylmethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyldimethylethoxysilane, or β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane can be used. The above-mentioned silane coupling agents may be used alone or in combination of two or more.

In particular, the crosslink density of the cured film of the coating layer using bifunctional compounds such as gamma-glycidoxypropylmethyldimethoxysilane and gamma-glycidoxypropylmethyldiethoxysilane is lower than the crosslink density of a system using trialkoxysilane. Therefore, while the film has excellent gas barrier properties and hot water treatment resistance, it also becomes a flexible cured film and has excellent bending resistance, so the gas barrier properties are less likely to deteriorate.

As the water-soluble polymer, polyvinyl alcohol resin or ethylene-vinyl alcohol copolymer can be used alone, or polyvinyl alcohol resin and ethylene-vinyl alcohol copolymer can be used in combination. In the coating layer of this embodiment, polyvinyl alcohol resin is preferable.

As the polyvinyl alcohol-based resin, generally, one obtained by saponifying polyvinyl acetate can be used. As the polyvinyl alcohol-based resin, it may be a partially saponified polyvinyl alcohol-based resin in which several tens of percent of acetate groups remain, a completely saponified polyvinyl alcohol in which no acetate groups remain, or a modified polyvinyl alcohol-based resin in which OH groups have been modified. As the polyvinyl alcohol-based resin, it is necessary to use at least one that undergoes crystallization to improve the film hardness of the gas barrier coating film, and preferably has a saponification degree of 70% or more. In addition, as for the degree of polymerization, any resin within the range used in the conventional sol-gel method (approximately 100 to 5000) can be used. Examples of such polyvinyl alcohol-based resins include RS resin "RS-110 (saponification degree = 99%, polymerization degree = 1,000)" manufactured by Kuraray Co., Ltd. and "GOHSENOL NM-14 (saponification degree = 99%, polymerization degree = 1,400)" manufactured by Nippon Synthetic Chemical Industry Co., Ltd.

As the ethylene-vinyl alcohol copolymer, a saponified product of a copolymer of ethylene and vinyl acetate, i.e., a product obtained by saponifying an ethylene-vinyl acetate random copolymer, can be used. For example, it includes a partially saponified product in which several tens of mol% of acetate groups remain, to a completely saponified product in which only a few mol% of acetate groups remain or no acetate groups remain, and is not particularly limited. However, from the viewpoint of barrier properties, the lower limit of the saponification degree is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more. The upper limit is 100% or less.

As a sol-gel catalyst, an acid or amine compound is suitable.

As the acid, for example, mineral acids such as sulfuric acid, hydrochloric acid, and nitric acid, as well as organic acids such as acetic acid and tartaric acid can be used.

The acid content is preferably 0.001 to 0.05 mol %, more preferably 0.01 to 0.03 mol %, based on the total molar amount of alkoxy groups in the metal alkoxide. If it is less than 0.001 mol %, the catalytic effect is too small, and if it is more than 0.05 mol %, the catalytic effect is too strong, causing the reaction rate to become too fast and tending to become non-uniform.

As the amine compound, a tertiary amine that is substantially insoluble in water and soluble in an organic solvent is preferable. Specifically, for example, N,N-dimethylbenzylamine, tripropylamine, tributylamine, tripentylamine, etc. can be used. In particular, N,N-dimethylbenzylamine is preferable.

The content of the amine compound is preferably, for example, 0.01 to 1.0 part by mass, and particularly 0.03 to 0.3 part by mass, per 100 parts by mass of the metal alkoxide. If it is less than 0.01 part by mass, the catalytic effect is too small, and if it is more than 1.0 part by mass, the catalytic effect is too strong, causing the reaction rate to become too fast and tending to become non-uniform.

The solvent preferably used is water or an alcohol such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropanol, or n-butanol.

The barrier coating layer formed as described above has a layer thickness of 100 to 500 nm, preferably 200 to 400 nm. This range is preferable because the coating film does not crack and sufficiently covers the surface of the deposited film.

When the barrier coating agent contains a silane coupling agent, 5 to 10 parts by mass of a water-soluble polymer such as a polyvinyl alcohol resin and 1 to 10 parts by mass of the silane coupling agent can be used per 100 parts by mass of alkoxysilane. This allows the flexibility of the film to be maintained. In the above, using more than 20 parts by mass of the silane coupling agent is not preferable as it increases the rigidity and brittleness of the barrier coating film that is formed.

In addition, when a silane coupling agent is not included, the ratio of metal alkoxide can be reduced and the barrier properties can be improved by using 10 to 20 parts by mass of a water-soluble polymer such as a polyvinyl alcohol resin per 100 parts by mass of alkoxysilane.

In the coating layer, the lower limit of the ratio of the mass of the metal alkoxide such as tetraethoxysilane converted into _SiO2 to the mass of the water-soluble resin such as polyvinyl alcohol is preferably 1.6 or more, more preferably 1.9 or more. The upper limit is preferably 3.9 or less, more preferably 3.5 or less. If the ratio exceeds 3.9, the barrier property may decrease in a post-process, etc., which is not preferable, and if the ratio is less than 1.6, the barrier property after retort treatment is decreased, which is not preferable.

The silicon atom to carbon atom ratio (Si/C) of the coating layer is preferably 1.30 or more and 1.65 or less. If it exceeds 1.65, the barrier properties may decrease in later processes, which is not preferable, and if it is less than 1.30, the barrier properties after heat sterilization treatment decrease, which is not preferable. The silicon atom to carbon atom ratio of the coating layer can be measured by X-ray photoelectron spectroscopy (XPS), specifically, under the conditions described in the examples.

(Film forming equipment)
Next, an example of a film forming apparatus 10 used in the manufacturing method of a barrier film will be described. As shown in Fig. 2, the film forming apparatus 10 includes a substrate transport mechanism 11A for transporting the substrate 1, a plasma pretreatment mechanism 11B for performing plasma pretreatment on the surface of the substrate 1, and a film forming mechanism 11C for forming a vapor deposition film 2. In the example shown in Fig. 5, the film forming apparatus 10 further includes a decompression chamber 12. The decompression chamber 12 has a decompression mechanism, such as a vacuum pump described later, for adjusting the atmosphere in at least a part of the space inside the decompression chamber 12 to atmospheric pressure or lower.

In the example shown in FIG. 2, the decompression chamber 12 includes a substrate transport chamber 12A in which the substrate transport mechanism 11A is located, a plasma pretreatment chamber 12B in which the plasma pretreatment mechanism 11B is located, and a film deposition chamber 12C in which the film deposition mechanism 11C is located. The decompression chamber 12 is preferably configured to prevent the atmospheres inside each chamber from mixing with each other. For example, as shown in FIG. 2, the decompression chamber 12 may be located between the substrate transport chamber 12A and the plasma pretreatment chamber 12B, between the plasma pretreatment chamber 12B and the film deposition chamber 12C, and between the substrate transport chamber 12A and the film deposition chamber 12C, and may have partitions 35a to 35c that separate each chamber.

The substrate transport chamber 12A, the plasma pretreatment chamber 12B, and the film formation chamber 12C will be described. The plasma pretreatment chamber 12B and the film formation chamber 12C are each provided in contact with the substrate transport chamber 12A, and each has a portion connected to the substrate transport chamber 12A. This allows the substrate 1 to be transported between the substrate transport chamber 12A and the plasma pretreatment chamber 12B, and between the substrate transport chamber 12A and the film formation chamber 12C without being exposed to the atmosphere. For example, between the substrate transport chamber 12A and the plasma pretreatment chamber 12B, the substrate 1 can be transported through an opening provided in the partition wall 35a. The substrate transport chamber 12A and the film formation chamber 12C have a similar structure, and the substrate 1 can be transported between the substrate transport chamber 12A and the film formation chamber 12C.

The function of the decompression mechanism of the decompression chamber 12 will be described. The decompression mechanism of the decompression chamber 12 is configured to reduce the pressure of the atmosphere in the space in which at least the plasma pretreatment mechanism 11B or the film formation mechanism 11C of the film formation apparatus 10 is located to below atmospheric pressure. The decompression mechanism may be configured to reduce the pressure of each of the substrate transfer chamber 12A, the plasma pretreatment chamber 12B, and the film formation chamber 12C, which are partitioned by partitions 35a to 35c, to below atmospheric pressure.

The configuration of the decompression mechanism of the decompression chamber 12 will be described. The decompression chamber 12 may have, for example, a vacuum pump connected to the plasma pretreatment chamber 12B. By adjusting the vacuum pump, the pressure in the plasma pretreatment chamber 12B when performing the plasma pretreatment described below can be appropriately controlled. In addition, the plasma supplied to the plasma pretreatment chamber 12B can be prevented from diffusing to other chambers by a method described below. The decompression mechanism of the decompression chamber 12 may have a vacuum pump connected to the film formation chamber 12C, similar to the vacuum pump connected to the plasma pretreatment chamber 12B. As the vacuum pump, a dry pump, a turbomolecular pump, a cryopump, a rotary pump, a diffusion pump, etc. can be used.

The substrate transport mechanism 11A for the substrate 1 of the film forming apparatus 10 according to this embodiment will be described together with the transport path of the substrate 1. The substrate transport mechanism 11A is a mechanism for transporting the substrate 1, which is arranged in the substrate transport chamber 12A. In the example shown in FIG. 2, the substrate transport mechanism 11A has an unwinding roller 13 to which a roll of the substrate 1 is attached, a winding roller 15 for winding up the substrate 1, and guide rolls 14a to 14d. The substrate 1 sent out from the substrate transport mechanism 11A is then transported by a pretreatment roller 20 (described later) arranged in the plasma pretreatment chamber 12B, and a film formation roller 25 (described later) arranged in the film formation chamber 12C.

Although not shown, the substrate conveying mechanism 11A may further include a tension pick-up roller. By having the substrate conveying mechanism 11A include a tension pick-up roller, the substrate 1 can be conveyed while adjusting the tension applied to the substrate 1.

(Plasma pretreatment mechanism)
The plasma pretreatment mechanism 11B will be described. The plasma pretreatment mechanism 11B is a mechanism for performing plasma pretreatment on the surface of the substrate 1. The plasma pretreatment mechanism 11B shown in FIG. 2 generates plasma P and performs plasma pretreatment on the surface of the substrate 1 using the generated plasma P. When the surface of the substrate 1 is activated by plasma pretreatment, for example, hydrogen is released from the substrate resin component to generate carbon radicals. Then, functional groups such as hydroxyl groups, carboxyl groups, and ketone groups are generated by combining with oxygen and hydrogen in the atmosphere. It is believed that the generation of such functional groups improves the adhesion between the substrate 1 and the deposition film 2. The plasma pretreatment mechanism 11B shown in FIG. 2 has a pretreatment roller 20 arranged in the plasma pretreatment chamber 12B, an electrode unit 21 facing the pretreatment roller 20, and a magnetic field forming unit 23 that forms a magnetic field between the pretreatment roller 20 and the electrode unit 21.

The pretreatment roller 20 will be described. FIG. 3 is an enlarged view of the area surrounded by the dashed line marked with the symbol VI in FIG. 2. Note that FIG. 3 omits the power supply wiring 31 connecting the power source 32 shown in FIG. 2 and the electrode unit 21 described later, and the plasma P generated by the plasma pretreatment mechanism 11B. The pretreatment roller 20 has a rotation axis X. The pretreatment roller 20 is provided so that at least the rotation axis X is located within the plasma pretreatment chamber 12B partitioned by the partition walls 35a and 35b. The pretreatment roller 20 is wrapped with a substrate 1 having a dimension in the direction of the rotation axis X. In the following description, the dimension of the substrate 1 in the direction of the rotation axis X is also referred to as the width of the substrate 1. The direction of the rotation axis X is also referred to as the width direction of the substrate 1.

As shown in FIG. 2, the pretreatment roller 20 may be provided so that a part of it is exposed to the substrate transport chamber 12A. In the example shown in FIG. 2, the plasma pretreatment chamber 12B and the substrate transport chamber 12A are connected through an opening provided in the partition 35a, and a part of the pretreatment roller 20 is exposed to the substrate transport chamber 12A through the opening. There is a gap between the partition 35a between the substrate transport chamber 12A and the plasma pretreatment chamber 12B and the pretreatment roller 20, and the substrate 1 can be transported from the substrate transport chamber 12A to the plasma pretreatment chamber 12B through the gap. Although not shown, the pretreatment roller 20 may be provided so that its entirety is located within the plasma pretreatment chamber 12B.

Although not shown, the pretreatment roller 20 may have a temperature adjustment mechanism that adjusts the temperature of the surface of the pretreatment roller 20. For example, the pretreatment roller 20 may have a temperature adjustment mechanism inside the pretreatment roller 20 that includes piping for circulating a temperature adjustment medium such as a refrigerant or a heat medium. The temperature adjustment mechanism adjusts the surface temperature of the pretreatment roller 20 to a target temperature, for example, within a range of -20°C or higher and 100°C or lower.

The pretreatment roller 20 has a temperature adjustment mechanism, which can prevent the substrate 1 from shrinking or being damaged by heat during plasma pretreatment.

The pretreatment roller 20 is made of a material containing at least one of stainless steel, iron, copper, and chromium. The surface of the pretreatment roller 20 may be treated with a hard chrome hard coat to prevent scratches. These materials are easy to process. In addition, by using the above materials for the pretreatment roller 20, the thermal conductivity of the pretreatment roller 20 itself is increased, making it easier to control the temperature of the pretreatment roller 20.

The electrode unit 21 will be described. In the example shown in FIG. 2 and FIG. 3, the electrode unit 21 has a first surface 21c facing the pretreatment roller 20 and a second surface 21d located on the opposite side of the first surface 21c. In the example shown in FIG. 2 and FIG. 3, the electrode unit 21 is a plate-shaped member, and both the first surface 21c and the second surface 21d are flat. The electrode unit 21 generates plasma between the pretreatment roller 20 by applying an AC voltage between the electrode unit 21 and the pretreatment roller 20. The electrode unit 21 preferably forms an electric field between the electrode unit 21 and the pretreatment roller 20 so that the generated plasma moves in a direction perpendicular to the surface of the substrate 1 toward the surface of the substrate 1. This allows the substrate 1 to be pretreated efficiently.

The number of electrode sections 21 is preferably two or more. The two or more electrode sections 21 are preferably arranged along the transport direction of the substrate 1. In the example shown in Figures 2 and 3, an example is shown in which the film forming device 10 has two electrode sections 21. In addition, the number of electrode sections 21 is, for example, 12 or less.

The effect of two or more electrode units 21 arranged along the transport direction of the substrate 1 will be described. As described above, plasma is generated between the electrode unit 21 and the pretreatment roller 20. The area in which plasma is generated expands as the dimension of the electrode unit 21 in the transport direction increases. On the other hand, when the electrode unit 21 is a flat plate-shaped member, the distance from the end of the first surface 21c, which is the surface of the electrode unit 21 facing the pretreatment roller 20, to the pretreatment roller 20 in the transport direction increases as the dimension of the electrode unit 21 in the transport direction increases, resulting in a decrease in the processing ability of the plasma.

In the film forming apparatus 10, two or more electrode units 21 are arranged along the transport direction of the substrate 1. Therefore, even if the dimensions of the electrode units 21 in the transport direction of the substrate 1 are small, plasma can be generated over a wide range in the transport direction. In addition, by reducing the dimensions of the electrode units 21, the distance from the end of the first surface 21c of the electrode units 21 in the transport direction to the pretreatment roller 20 can be reduced, and plasma can be generated uniformly in the transport direction.

2 and 3, the electrode portion 21 has a first end 21e and a second end 21f located on the first surface 21c of the electrode portion 21. The first end 21e is an upstream end in the transport direction of the substrate 1, and the second end 21f is a downstream end in the transport direction of the substrate 1. As described above, by reducing the dimension of the electrode portion 21 in the transport direction of the substrate 1, the distance from the first end 21e and the second end 21f of the electrode portion 21 to the pretreatment roller 20 in the transport direction can be reduced. The dimension of the electrode portion 21 in the transport direction of the substrate 1 corresponds to the angle θ shown in FIG. 3. The angle θ is the angle between a straight line passing through the first end 21e and the rotation axis X and a straight line passing through the second end 21f and the rotation axis X. The angle θ is preferably 20° or more and 90° or less, more preferably 60° or less, and even more preferably 45° or less. By setting the angle θ within the above range, when the first surface 21c of the electrode unit 21 is flat, plasma can be generated uniformly in the transport direction between the electrode unit 21 and the pretreatment roller 20.

The material of the electrode portion 21 is not particularly limited as long as it is conductive. Specifically, aluminum, copper, and stainless steel are preferably used as materials for the electrode portion 21.

The thickness L3 of the electrode unit 21 when viewed in a direction perpendicular to the first surface 21c of the electrode unit 21 is not particularly limited, but is, for example, 15 mm or less. When the thickness of the electrode unit 21 is the above value, the magnetic field forming unit 23 can effectively form a magnetic field between the pretreatment roller 20 and the electrode unit 21. In addition, the thickness L3 of the electrode unit 21 is, for example, 3 mm or more.

The magnetic field forming unit 23 will now be described. As shown in Figures 2 and 3, the magnetic field forming unit 23 is provided on the side of the electrode unit 21 opposite the side facing the pretreatment roller 20. The magnetic field forming unit 23 is a member that forms a magnetic field between the pretreatment roller 20 and the electrode unit 21. The magnetic field between the pretreatment roller 20 and the electrode unit 21 contributes to the generation of higher density plasma, for example, when plasma is generated using the plasma pretreatment mechanism 11B. The magnetic field forming unit 23 shown in Figures 2 and 3 has a first magnet 231 and a second magnet 232 provided on the second surface 21d of the electrode unit 21.

The number of magnetic field forming units 23 is preferably two or more. When the plasma pretreatment mechanism 11B has two or more electrode units 21 and two or more magnetic field forming units 23, it is preferable that each of the two or more magnetic field forming units 23 is provided on the side of each of the two or more electrode units 21 opposite the side facing the pretreatment roller 20. In the example shown in Figures 2 and 3, each of the two magnetic field forming units 23 is provided on the second surface 21d of each of the two electrode units 21.

The structure of the first magnet 231 and the second magnet 232 in the normal direction of the second surface 21d of the electrode part 21 will be described. As shown in FIG. 2 and FIG. 3, the first magnet 231 and the second magnet 232 each have an N pole and an S pole. The symbol N shown in FIG. 2 and FIG. 3 indicates the N pole of the first magnet 231 or the second magnet 232. Also, the symbol S shown in FIG. 2 and FIG. 3 indicates the S pole of the first magnet 231 or the second magnet 232. One of the N pole or S pole of the first magnet 231 is located closer to the substrate 1 than the other. Also, the other of the N pole or S pole of the second magnet 232 is located closer to the substrate 1 than the other. In the example shown in FIG. 2 and FIG. 3, the N pole of the first magnet 231 is located closer to the substrate 1 than the S pole of the first magnet 231, and the S pole of the second magnet 232 is located closer to the substrate 1 than the N pole of the second magnet. Although not shown, the south pole of the first magnet 231 may be located closer to the substrate 1 than the north pole of the first magnet 231, and the north pole of the second magnet 232 may be located closer to the substrate 1 than the south pole of the second magnet 232.

Next, the structure of the first magnet 231 and the second magnet 232 in the planar direction of the second surface 21d of the electrode unit 21 will be described. Figure 4 is a plan view of the electrode unit 21 and the magnetic field generating unit 23 shown in Figure 2, viewed from the magnetic field generating unit 23 side. Figure 5 is a cross-sectional view showing a cross section taken along line VIII-VIII in Figure 4. Also, in Figure 4, direction D1 is the direction in which the rotation axis X of the pre-treatment roller 20 extends.

As shown in Figs. 4 and 5, the first magnet 231 has a first axial portion 231c. As shown in Fig. 4, the first axial portion 231c extends along the direction D1, i.e., along the rotation axis X of the pretreatment roller 20. The first magnet 231 provided on one electrode unit 21 may have one first axial portion 231c, or may have two or more first axial portions 231c. In the example shown in Fig. 4, the first magnet 231 provided on one electrode unit 21 has one first axial portion 231c.

As shown in Figs. 4 and 5, the second magnet 232 has a second axial portion 232c. As shown in Fig. 4, the second axial portion 232c also extends along the direction D1, i.e., along the rotation axis X, similar to the first axial portion 231c.

Since both the first magnet 231 and the second magnet 232 include a portion that extends along the rotation axis X, the uniformity of the strength of the magnetic field formed around the substrate 1 in the width direction of the substrate 1 can be increased. This makes it possible to increase the uniformity of the distribution density of the plasma formed around the substrate 1 in the width direction of the substrate 1.

The second magnet 232 provided on one electrode unit 21 may have one second axial portion 232c, or may have two or more second axial portions 232c. In the example shown in Figures 4 and 5, the second magnet 232 provided on one electrode unit 21 has two second axial portions 232c. The two second axial portions 232c may be positioned so as to sandwich the first axial portion 231c in the direction D2 perpendicular to the rotation axis X in the planar direction of the second surface 21d of the electrode unit 21.

The dimension L4 of the first axial portion 231c and the dimension L5 of the second axial portion 232c in the transport direction of the substrate 1 shown in FIG. 5 are not particularly limited. Furthermore, the ratio between the dimension L4 of the first axial portion 231c and the dimension L5 of the second axial portion 232c in the transport direction of the substrate 1 is not particularly limited. The dimension L4 of the first axial portion 231c and the dimension L5 of the second axial portion 232c may be equal, or the dimension L4 of the first axial portion 231c may be greater than the dimension L5 of the second axial portion 232c.

The distance L6 between the first axial portion 231c and the second axial portion 232c in the direction D2 is set so that a magnetic field generated by the first axial portion 231c and the second axial portion 232c is formed between the pretreatment roller 20 and the electrode portion 21.

The second magnet 232 may surround the first magnet 231 when the magnetic field generating unit 23 is viewed along the normal direction of the second surface 21d of the electrode unit 21. For example, as shown in FIG. 4, the second magnet 232 may have two second axial portions 232c and two connecting portions 232d that are provided to connect the two second axial portions 232c.

Examples of the types of magnets used as the magnetic field generating unit 23, such as the first magnet 231 and the second magnet 232, include permanent magnets such as ferrite magnets and rare earth magnets such as neodymium and samarium cobalt (samarium cobalt). An electromagnet can also be used as the magnetic field generating unit 23.

The magnetic flux density of the magnets of the magnetic field forming unit 23, such as the first magnet 231 and the second magnet 232, is, for example, 100 Gauss or more and 10,000 Gauss or less. If the magnetic flux density is 100 Gauss or more, a sufficiently strong magnetic field can be formed between the pretreatment roller 20 and the electrode unit 21, thereby generating a sufficiently high density plasma and forming a good pretreatment surface at high speed. On the other hand, in order to increase the magnetic flux density on the surface of the substrate 1 to more than 10,000 Gauss, an expensive magnet or magnetic field generating mechanism is required.

Although not shown, the plasma pretreatment mechanism 11B may have a plasma raw material gas supply unit. The plasma raw material gas supply unit supplies a gas that is a raw material for plasma into the plasma pretreatment chamber 12B. The configuration of the plasma raw material gas supply unit is not particularly limited. For example, the plasma raw material gas supply unit is provided on the wall surface of the plasma pretreatment chamber 12B and includes a hole for ejecting the gas that is a raw material for plasma. The plasma raw material gas supply unit may also have a nozzle that ejects the plasma raw material gas at a position closer to the substrate 1 than the wall surface of the plasma pretreatment chamber 12B. The plasma raw material gas supplied by the plasma raw material gas supply unit may be, for example, an inert gas such as argon, an active gas such as oxygen, nitrogen, carbon dioxide, or ethylene, or a mixed gas of these gases. As the plasma raw material gas, one of the inert gases may be used alone, one of the active gases may be used alone, or a mixed gas of two or more gases contained in the inert gas or active gas may be used. As the plasma raw material gas, a mixed gas of an inert gas such as argon and an active gas may be used. As an example, the plasma raw material gas supply unit supplies a mixed gas of argon (Ar) and oxygen (O ₂ ).

The plasma pretreatment mechanism 11B supplies plasma having a plasma density of, for example, 100 W·sec/m ² or more and 8000 W·sec/m ² or less between the pretreatment roller 20 and the electrode unit 21 .

In the example shown in FIG. 2, the plasma pretreatment mechanism 11B is disposed in a plasma pretreatment chamber 12B separated by a partition from the substrate transport chamber 12A and the deposition chamber 12C. By separating the plasma pretreatment chamber 12B from other areas such as the substrate transport chamber 12A and the deposition chamber 12C, it becomes easier to adjust the atmosphere in the plasma pretreatment chamber 12B independently. This makes it easier to control the plasma raw material gas concentration in the space where the pretreatment roller 20 and the electrode unit 21 face each other, improving the productivity of laminated films.

(Film formation mechanism)
Next, the film formation mechanism 11C will be described. In the example shown in Fig. 2, the film formation mechanism 11C includes a film formation roller 25 and an evaporation mechanism 24 disposed in a film formation chamber 12C.

The deposition roller 25 will be described. The deposition roller 25 is a roller that wraps around and transports the substrate 1 with the treated surface of the substrate 1 that has been pretreated in the plasma pretreatment mechanism 11B facing outward.

The material of the film-forming roller 25 will be described. The film-forming roller 25 is preferably formed from a material containing at least one of stainless steel, iron, copper, and chromium. The surface of the film-forming roller 25 may be treated with a hard chrome hard coat to prevent scratches. These materials are easy to process. In addition, by using the above-mentioned materials as the material of the film-forming roller 25, the thermal conductivity of the film-forming roller 25 itself is increased, resulting in excellent temperature controllability when performing temperature control. The surface average roughness Ra of the film-forming roller 25 is, for example, 0.1 μm or more and 10 μm or less.

Although not shown, the film-forming roller 25 may have a temperature adjustment mechanism for adjusting the temperature of the surface of the film-forming roller 25. The temperature adjustment mechanism has, for example, a circulation path for circulating a cooling medium or a heat source medium inside the film-forming roller 25. The cooling medium (refrigerant) is, for example, an ethylene glycol aqueous solution, and the heat source medium (heat medium) is, for example, silicone oil. The temperature adjustment mechanism may have a heater installed at a position opposite the film-forming roller 25. When the film-forming mechanism 11C forms a film by a deposition method, the temperature adjustment mechanism preferably adjusts the surface temperature of the film-forming roller 25 to a target temperature within a range of -20°C to 200°C in terms of the constraints on the heat resistance of related mechanical parts and versatility. By having the film-forming roller 25 have a temperature adjustment mechanism, it is possible to suppress the temperature fluctuation of the substrate 1 caused by the heat generated during film formation.

The evaporation mechanism 24 will be described. FIG. 6 is an enlarged view of the area surrounded by the dashed line marked with the symbol IX in FIG. 2, showing a specific form of the evaporation mechanism 24 that was omitted in FIG. 5, and showing the evaporation material supply unit 61 that supplies the evaporation material that was omitted in FIG. 2. Note that the decompression chamber 12 and the partitions 35b and 35c are omitted in FIG. 6. The evaporation mechanism 24 is a mechanism that evaporates the evaporation material containing aluminum. The evaporated evaporation material adheres to the substrate 1, forming an evaporation film containing aluminum on the surface of the substrate 1. The evaporation mechanism 24 in this embodiment employs a resistance heating type. In the example shown in FIG. 6, the evaporation mechanism 24 has a boat 24b. In this embodiment, the boat 24b has a power source (not shown) and a resistor (not shown) electrically connected to the power source. A plurality of boats 24b may be arranged in the width direction of the substrate 1.

As shown in FIG. 6, the film forming mechanism 11C may have a deposition material supply unit 61 that supplies deposition material to the evaporation mechanism 24. FIG. 6 shows an example in which the deposition material supply unit 61 continuously delivers aluminum metal wire.

Although not shown, the film-forming mechanism 11C has a gas supply mechanism. The gas supply mechanism is a mechanism that supplies gas between the evaporation mechanism 24 and the film-forming roller 25. The gas supply mechanism supplies at least oxygen gas. The oxygen gas reacts with or bonds with an evaporation material such as aluminum that evaporates from the evaporation mechanism 24 and heads toward the substrate 1 on the film-forming roller 25. This allows a vapor deposition film containing aluminum oxide to be formed on the surface of the substrate 1.

The film forming mechanism 11C also includes a plasma supply mechanism 50 that supplies plasma between the surface of the substrate 1 and the evaporation mechanism 24. In the examples shown in FIG. 2 and FIG. 6, the plasma supply mechanism 50 has a hollow cathode 51. In this embodiment, the hollow cathode 51 is a cathode having a hollow portion that is partially open. The hollow cathode 51 can generate plasma in the hollow portion. In the example shown in FIG. 6, the hollow cathode 51 is provided so that the opening of the hollow portion of the hollow cathode 51 is located diagonally above the boat 24b. Although not shown, the plasma supply mechanism 50 according to this embodiment has an anode facing the opening that draws plasma from the opening of the hollow portion of the hollow cathode 51. The plasma supply mechanism 50 according to this embodiment can generate strong plasma between the surface of the substrate 1 and the evaporation mechanism 24 by generating plasma in the hollow portion of the hollow cathode 51 and drawing the plasma between the surface of the substrate 1 and the evaporation mechanism 24 by the opposing anode. The position of the opposing anodes is not particularly limited as long as the opposing anodes can draw plasma from the opening of the hollow cathode 51 and supply plasma between the surface of the substrate 1 and the evaporation mechanism 24. In this embodiment, the opposing anodes are arranged on both sides of the boat 24b in the width direction of the substrate 1. In this case, the film formation mechanism 11C has a plurality of boats 24b and a plurality of opposing anodes, and the plurality of boats 24b and the plurality of opposing anodes may be arranged alternately in the width direction of the substrate 1. Although not shown, the plasma supply mechanism 50 may have a raw material supply device that supplies plasma raw material gas at least into the hollow cathode 51. As the plasma raw material gas supplied by the raw material supply device, for example, a gas similar to the gas that can be used as the plasma raw material gas supplied by the plasma raw material gas supply unit of the plasma pretreatment mechanism 11B can be used.

By using the plasma supply mechanism 50 to supply plasma between the surface of the substrate 1 and the evaporation mechanism 24, plasma assist during deposition can be performed, activating the aluminum and oxygen gas evaporated in the evaporation mechanism 24 and promoting the reaction or bonding of the aluminum and oxygen gas. This can increase the proportion of aluminum present as aluminum oxide in the deposition film 2 formed on the surface of the substrate 1, stabilizing the properties of the deposition film 2.

Although not shown, the film forming apparatus 10 may be provided with a substrate charge removal section in the substrate transport chamber 12A located downstream of the film formation chamber 12C in the transport direction of the substrate 1, which performs post-processing to remove charge generated on the substrate 1 due to film formation by the film formation mechanism 11C. The substrate charge removal section may be provided to remove charge from one side of the substrate 1, or may be provided to remove charge from both sides of the substrate 1.

The device used as the substrate charge removal section for post-treating the substrate 1 is not particularly limited, but examples that can be used include a plasma discharge device, an electron beam irradiation device, an ultraviolet irradiation device, a static elimination bar, a glow discharge device, and a corona treatment device.

When performing post-treatment by forming a discharge using a plasma treatment device or glow discharge device, a discharge gas such as argon, oxygen, nitrogen, helium, or a mixture of these gases can be supplied near the substrate 1, and post-treatment can be performed using any discharge method, such as alternating current (AC) plasma, direct current (DC) plasma, arc discharge, microwave, or surface wave plasma. In a reduced pressure environment, it is most preferable to perform post-treatment using a plasma discharge device.

The substrate charge removal section is installed in a portion of the substrate transport chamber 12A that is located downstream of the film-forming chamber 12C in the transport direction of the substrate 1, and by removing the charge from the substrate 1, the substrate 1 can be quickly separated from the film-forming roller 25 at a predetermined position and transported. This enables stable substrate transport, prevents damage to the substrate 1 or deterioration in quality due to charging, and improves post-processing suitability by improving the wettability of the front and back surfaces of the substrate.

(power supply)
In the example shown in FIG. 2, the film forming apparatus 10 further includes a power source 32 electrically connected to the pretreatment roller 20 and the electrode unit 21. In the example shown in FIG. 5, the power source 32 is electrically connected to the pretreatment roller 20 and the electrode unit 21 via the power supply wiring 31. The power source 32 is, for example, an AC power source. When the power source 32 is an AC power source, the power source 32 can apply an AC voltage having a frequency of, for example, 20 kHz or more and 500 kHz or less between the pretreatment roller 20 and the electrode unit 21. The input power that can be applied by the power source 32 (power that can be applied per 1 m width of the electrode unit 21 in the width direction of the substrate 1) is not particularly limited, but is, for example, 0.5 kW/m or more and 20 kW/m or less. The pretreatment roller 20 may be installed at an electrically earth level or at an electrically floating level.

(Method of manufacturing a barrier film)
Next, a method for manufacturing the barrier film shown in Fig. 1 using the above-mentioned film forming apparatus 10 will be described. First, a film forming method for forming a vapor deposition film 2 on the surface of a substrate 1 will be described. In film formation using the film forming apparatus 10, a plasma pretreatment step of performing plasma pretreatment on the surface of the substrate 1 using a plasma pretreatment mechanism 11B and a film formation step of forming a vapor deposition film on the surface of the substrate 1 using a film formation mechanism 11C are performed while the substrate 1 is transported along the above-mentioned transport path of the substrate 1. The transport speed of the substrate 1 is preferably 200 m/min or more, and more preferably 400 m/min or more and 1000 m/min or less.

(Plasma pretreatment process)
The plasma pretreatment step is performed, for example, by the following method. First, a plasma raw material gas is supplied into the plasma pretreatment chamber 12B. Next, the above-mentioned AC voltage is applied between the pretreatment roller 20 and the electrode unit 21. When applying the AC voltage, input power control, impedance control, or the like may be performed.

The plasma raw material gas supplied in the pretreatment is oxygen alone or a mixture of oxygen gas and an inert gas, which is supplied from a gas storage section through a flow controller while measuring the gas flow rate. The inert gas may be one or a mixture of two or more gases selected from the group consisting of argon, helium, and nitrogen.

For plasma treatment, the mixture ratio of oxygen gas to the inert gas, oxygen gas/inert gas, is preferably 6/1 to 1/1, and more preferably 5/2 to 3/2.5.

By setting the mixing ratio to 6/1 to 1/1, the energy required to form the evaporated aluminum film on the resin substrate increases, and by setting it to 5/2 to 3/2, the degree of oxidation of the evaporated aluminum oxide film can be increased, ensuring adhesion between the evaporated aluminum oxide film and the substrate.

By applying an AC voltage, plasma is generated simultaneously with glow discharge, and the plasma P becomes denser between the pretreatment roller 20 and the magnetic field forming unit 23. In this way, plasma P can be supplied between the pretreatment roller 20 and the magnetic field forming unit 23. This plasma P can be used to perform plasma (ion) pretreatment on the surface of the substrate 1.

The plasma intensity per unit area in the plasma treatment is 50 W·sec/ ^m2 or more and 8000 W·sec/m2 ^or less, and at 50 W·sec/m2 ^{or less} , the effect of the plasma pretreatment is not observed, and at 8000 W·sec/m2 or ^more , the resin substrate tends to deteriorate due to the plasma, such as consumption, damage, coloring, and baking of the resin substrate. In particular, the plasma intensity in the plasma pretreatment to form an aluminum oxide layer is preferably 100 W·sec/m2 ^{or more} and 1000 W·sec/m2 or ^less .

The pressure in the plasma pretreatment chamber 12B when an AC voltage is applied between the pretreatment roller 20 and the electrode unit 21 is reduced to below atmospheric pressure by the decompression chamber 12. In this case, the pressure in the plasma pretreatment chamber 12B is adjusted, for example, so that a glow discharge can be generated between the pretreatment roller 20 and the electrode unit 21 by applying an AC voltage. The pressure in the plasma pretreatment chamber 12B when an AC voltage is applied between the pretreatment roller 20 and the electrode unit 21 can be set and maintained at approximately 0.1 Pa or more and 100 Pa or less, and is particularly preferably 1 Pa or more and 20 Pa or less.

The action of the magnetic field forming unit 23 in the plasma pretreatment process will be explained. The magnetic field forming unit 23 forms a magnetic field between the pretreatment roller 20 and the electrode unit 21. The magnetic field can act to capture and accelerate electrons present between the pretreatment roller 20 and the electrode unit 21. Therefore, in the area where the magnetic field is formed, the frequency of collisions between the electrons and the plasma raw material gas can be increased, and the plasma density can be increased and localized, thereby improving the efficiency of the plasma pretreatment.

(Film forming process)
In the film formation process, the film formation mechanism 11C is used to form a film on the surface of the substrate 1. As an example of the film formation process, a case in which an aluminum oxide vapor deposition film is formed using the film formation mechanism 11C having an evaporation mechanism 24 shown in FIG.

First, a deposition material containing aluminum is supplied into the boat 24b of the evaporation mechanism 24 so as to face the deposition roller 25. An aluminum metal wire can be used as the deposition material. In the example shown in FIG. 6, the deposition material is supplied to the boat 24b by continuously sending the aluminum metal wire into the boat 24b using the deposition material supply unit 61.

The aluminum is evaporated in the boat 24b by heating. For convenience, FIG. 6 illustrates evaporated aluminum vapor 63. The oxygen gas that oxidizes the aluminum may be supplied as oxygen alone or as a mixed gas with an inert gas such as argon, but by controlling the amount of oxygen, it is possible to achieve both barrier properties and transparency. The pressure at this time is preferably 0.05 Pa or more and 8.00 Pa or less.

Furthermore, a method of supplying plasma between the surface of the substrate 1 and the evaporation mechanism 24 by the plasma supply mechanism 50, i.e., plasma assist during deposition, will be described. In this embodiment, plasma is generated within the cavity of the hollow cathode 51 of the plasma supply mechanism 50. Next, a discharge is generated between the hollow cathode 51 and the opposing anode, and the plasma within the cavity of the hollow cathode 51 is drawn between the surface of the substrate 1 and the evaporation mechanism 24.

In this embodiment, the discharge generated between the hollow cathode 51 and the opposing anode is an arc discharge. An arc discharge means a discharge with a current value of, for example, 10 A or more.

By evaporating aluminum while supplying plasma between the surface of the substrate 1 and the evaporation mechanism 24, plasma is supplied to the aluminum vapor 63. Supplying plasma can promote the reaction or bonding between the aluminum vapor 63 and oxygen gas. This allows the aluminum vapor 63 to be oxidized before it reaches the surface of the substrate 1. The evaporated and oxidized aluminum adheres to the substrate 1, forming an aluminum oxide vapor deposition film on the surface of the substrate 1, and the barrier film shown in FIG. 1 can be manufactured.

The plasma raw material gas supplied by the plasma supply mechanism 50 is preferably argon gas.

In this embodiment, a plasma pretreatment process is carried out before the film formation process, in which plasma is supplied to the surface of the substrate 1. In the plasma pretreatment process, an AC voltage is applied between the electrode unit 21 and the pretreatment roller 20. In addition, a magnetic field is generated in the space between the electrode unit 21 and the pretreatment roller 20 by using the magnetic field forming unit 23 located on the side of the surface of the electrode unit 21 opposite to the surface facing the pretreatment roller 20. This makes it possible to efficiently generate plasma in the space between the electrode unit 21 and the pretreatment roller 20, and to make the plasma enter perpendicularly to the surface of the substrate 1 wrapped around the pretreatment roller 20. This makes it possible to improve the adhesion between the film formed in the film formation process and the substrate 1.

(Aging treatment after film formation process)
The barrier film roll that has been subjected to the above-mentioned film-forming process is then subjected to an aging treatment (heating treatment) for a predetermined period of time, which promotes the introduction of hydroxyl groups into the vapor-deposited aluminum oxide film, resulting in the formation of a vapor-deposited film with excellent oxygen permeability and water vapor permeability.

The aging temperature is preferably 50°C or higher and 60°C or lower. The lower limit of the aging time is 24 hours (1 day) or higher, and more preferably 48 hours (2 days) or higher. The upper limit is 144 hours (6 days) or lower, and more preferably 96 hours (4 days) or lower. The aging humidity is not particularly limited, but does not need to be high humidity, and a normal relative humidity of 40% to 70% is sufficient.

(Covering layer forming process)
The coating layer 3 can be produced by the following method. First, the above metal alkoxide, the water-soluble polymer, the silane coupling agent added as necessary, the sol-gel catalyst, the acid, and an organic solvent such as water as a solvent, methyl alcohol, ethyl alcohol, isopropanol, etc., are mixed to prepare a barrier coating agent. Next, the above barrier coating agent is applied on the aluminum oxide vapor deposition film by a conventional method and dried. This drying step further advances the polycondensation of the silanol generated from the above metal alkoxide and the silane coupling agent, forming a coating film. The drying conditions include a temperature of 20 to 200°C, which is equal to or lower than the melting point of the plastic substrate, preferably a temperature in the range of 50 to 180°C, and a heat treatment for 3 seconds to 10 minutes. This allows the coating layer 3 made of the above barrier coating agent to be formed on the aluminum oxide vapor deposition film. The above coating operation may be further repeated on the first coating film to form a plurality of coating films consisting of two or more layers.

The barrier film roll that has undergone the above coating layer formation process is then aged (heated) for a specified period of time. This allows the coating layer to condense appropriately, resulting in a barrier film whose barrier properties are less likely to deteriorate after retort testing.

The lower limit of the aging temperature after the coating layer formation process is preferably 40°C or higher, more preferably 50°C or higher. The upper limit is preferably 100°C or lower, more preferably 70°C or lower. The lower limit of the aging time is 24 hours (1 day) or higher, more preferably 48 hours (2 days) or higher. The upper limit is 144 hours (6 days) or lower, more preferably 96 hours (4 days) or lower. The aging humidity is not particularly limited, but does not need to be high humidity, and a normal relative humidity of 40% to 70% is sufficient.

(Film formation process 2)
An aluminum oxide film may be further deposited on the coating layer under the same conditions as those for the above-mentioned film deposition step and aging treatment.

(Coating layer forming step 2)
A coating layer may be further formed on the aluminum oxide vapor-deposited film vapor-deposited through the film-forming step 2. The film can be formed under the same conditions as those in the coating layer forming step.

(Laminate)
Fig. 7 is a cross-sectional view showing an example of a laminate using the barrier film according to the present embodiment. This laminate 100 is a laminate using the barrier film 100A of Fig. 1. That is, the barrier film 100A is composed of a first polypropylene base material 110, a base layer 115, a vapor deposition film 120, and a coating layer 130 having a barrier property. One surface of the barrier film on the first polypropylene base material 110 side is laminated with a sealant layer 150 via a first adhesive layer 161, and the other surface of the barrier film on the coating layer 130 side is laminated with a second polypropylene base material 140 via an adhesive layer 162. That is, it is a three-layer film configuration with the barrier film as an intermediate layer, that is, the second polypropylene base material 140/second adhesive layer 162/barrier film/first adhesive layer 161/sealant layer 150. Hereinafter, the configuration other than the barrier film A will be described.

[Adhesive layer]
The surface of the barrier film facing the first polypropylene base material 110 is laminated to the sealant layer 150 via a first adhesive layer 161, and the surface of the barrier film facing the coating layer 130 is laminated to the second polypropylene base material 140 via an adhesive layer 162. This improves the adhesion between the barrier film and the sealant layer, and between the first polypropylene base material and the second base material, and suppresses deterioration of the barrier properties during heat sterilization treatment such as retort or boiling.

The first adhesive layer 161 and the second adhesive layer 162 may be a one-component curing adhesive, a two-component curing adhesive, or a non-curing adhesive. The adhesive may be a solventless adhesive or a solvent-based adhesive suitable for dry lamination.

Examples of solvent-free adhesives, i.e., non-solvent lamination adhesives, include polyether-based adhesives, polyester-based adhesives, silicone-based adhesives, epoxy-based adhesives, and urethane-based adhesives. Among these, urethane-based adhesives are preferred, and two-component curing urethane-based adhesives are more preferred.

Examples of solvent-based adhesives include rubber-based adhesives, vinyl-based adhesives, olefin-based adhesives, silicone-based adhesives, epoxy-based adhesives, phenol-based adhesives, and urethane-based adhesives. Among these, urethane-based adhesives are preferred, and two-component curing urethane-based adhesives are more preferred.

The thickness of the adhesive layer is, for example, 0.1 μm or more and 10 μm or less, preferably 0.2 μm or more and 8 μm or less, and more preferably 0.5 μm or more and 6 μm or less.

[Second polypropylene base material]
The second polypropylene base material 140 is laminated to the surface of the barrier film facing the covering layer 30 via a second adhesive layer 162. Here, the second polypropylene base material may be the same as the first polypropylene base material 110, and therefore a description thereof will be omitted.

In the case of a three-layer structure as shown in FIG. 7, the printing layer (not shown) may be formed on the surface of the outermost layer of the second polypropylene base material 140, or on the surface of the second polypropylene base material 140 on the side of the second adhesive layer 162.

[Sealant layer]
The sealant layer 150 contains a resin material that can be fused to each other by heat. Examples of the resin material that can be fused to each other by heat include polyolefins, and specific examples of the resin material that can be fused to each other by heat include polyethylenes such as low-density polyethylene, linear low-density polyethylene, and medium-density polyethylene, polypropylene, polybutene, methylpentene polymers, and cyclic olefin copolymers.

The sealant layer is preferably made of polypropylene. This allows the three-layer film to be made entirely of polypropylene, making it possible to make the packaging material a mono-material. After collecting used packaging material, there is no need to separate the base material and the sealant layer, improving the recyclability of the packaging material. By making the sealant layer out of polypropylene, oil resistance can also be improved, making it possible to make the sealant layer able to withstand heat sterilization treatment.

The polypropylene content in the sealant layer is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more. This can improve the recyclability of the packaging material, for example.

When the sealant layer is made of polypropylene, the content of polypropylene in the total amount of resin material contained in the laminate is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 88% by mass or more, and particularly preferably 90% by mass or more. This makes it possible to produce, for example, a mono-material packaging material using the laminate, thereby improving the recyclability of the packaging material.

Examples of polypropylene include propylene homopolymers, propylene random copolymers such as propylene-α-olefin random copolymers, and propylene block copolymers such as propylene-α-olefin block copolymers. Details of the α-olefins are as described above. From the viewpoint of heat sealability, the density of the polypropylene is, for example, 0.88 g/cm3 or more and 0.92 g/cm3 or less. The density is measured in accordance with JIS K7112, particularly the D method (density gradient tube method, 23°C). From the viewpoint of reducing the environmental load, biomass-derived polypropylene and/or recycled polypropylene may be used.

The sealant layer may contain additives. Examples of additives include crosslinkers, antioxidants, antiblocking agents, slip agents, UV absorbers, light stabilizers, fillers, reinforcing agents, lubricants, antistatic agents, pigments, and modifying resins. For example, the sealant layer may contain an antistatic agent. This can suppress the generation of static electricity on the surface of the laminate, and can suppress, for example, adhesion between laminates.

The sealant layer may have a single-layer structure or a multi-layer structure. The thickness of the sealant layer is preferably 10 μm or more and 200 μm or less, more preferably 20 μm or more and 150 μm or less. When the thickness is equal to or more than the lower limit, for example, the lamination strength of a packaging material including the laminate can be further improved. When the thickness is equal to or less than the upper limit, for example, the processability of the laminate can be further improved. When a pouch (particularly a retort pouch) is produced from the laminate, the thickness of the sealant layer is more preferably 30 μm or more and 100 μm or less.

From the viewpoint of heat sealability, the sealant layer is preferably an unstretched resin film, more preferably an unstretched polypropylene film. The resin film can be produced, for example, by using a casting method, a T-die method, or an inflation method. The sealant layer may be laminated via an adhesive layer as in this embodiment, or the sealant layer may be formed by melt-extruding a resin material that can be fused to each other by heat onto a barrier film.

[Other lamination examples]
8 shows an example in which the covering layer 130 of the barrier film A is laminated to the sealant layer 150 via a first adhesive layer 161. Thus, in the present invention, the laminate is not limited to a three-layer film structure, and may be a two-layer structure.

[Packaged products]
The laminate can be used as a packaging product such as a packaging bag for containing contents such as food by forming the laminate into a bag shape with the sealant layer on the inside. The laminate of the present invention is a heat sterilized laminate used for a packaging bag for containing retort food or boiled food.

The term "heat sterilization" includes not only retort processing but also boiling processing. Boiling processing means heat sterilization at 60 to 100°C for 10 to 60 minutes, for example.

Retort processing refers to a heating and pressure sterilization process at 100 to 140°C. The F value, which is a concept that represents the integral value of the load heat amount, is 4 or more, more specifically, a heating and pressure sterilization process of 121°C for 3 minutes or more, or 120°C for 4 minutes or more as stipulated in the Food Sanitation Act, is preferable. More specifically, 120°C for 30 to 60 minutes is the most common, but semi-retort at 105 to 115°C for 30 to 60 minutes or high retort (HTST) at 130 to 140°C for 30 to 60 minutes are also acceptable.

[Complex Elastic Modulus and Indentation Hardness of Coating Layer]
In the present invention, the composite elastic modulus and indentation hardness after lamination and the above-mentioned heat sterilization treatment are measured by a nanoindentation method from a cross section of the coating layer of the laminate, and the composite elastic modulus is 5.0 GPa to 8.5 GPa and the indentation hardness is 0.9 GPa to 1.7 GPa. When the composite elastic modulus and indentation hardness are within this range, the deterioration of the barrier property of the laminate can be suppressed not only after boiling treatment but also after retort treatment.

It is even more preferable that the composite elastic modulus is 6.0 GPa or more and 8.5 GPa or less, and the indentation hardness is 1.0 GPa or more and 1.5 GPa or less, so that the deterioration of the barrier properties can be suppressed even after high-temperature retort processing of the laminate.

The indentation hardness of the coating layer is calculated by the following formula (1): Furthermore, the composite elastic modulus of the coating layer is calculated by the following formula (2).
Indentation hardness = Pmax / A (1)

Where:
Pmax: Maximum load (unit: μN)
A: contact projection area at maximum depth (unit: μm ² )
S: Contact stiffness.

The composite modulus and indentation hardness of the coating layer of the laminate after heat sterilization are measured by embedding the laminate after heat sterilization in epoxy resin or the like, and processing it with a microtome to expose the cross section of the coating layer. This allows measurements to be made from the "cross section" of the coating layer of the laminate by nanoindentation. This method allows the composite modulus and indentation hardness of the coating layer to be measured without peeling the laminate to expose the coating layer. The cross section is obtained by cutting the film in the thickness direction perpendicular to the main surface. The cross section was prepared by preparing a block in which the film was embedded in embedding resin, and cutting the block using a commercially available rotary microtome at room temperature (23°C). Finishing was performed with a diamond knife.

The indentation hardness and composite modulus of the cross section of the coating layer are measured by the nanoindentation method. First, an indenter is placed on the cross section of the coating layer, and the indenter is pressed into the cross section to a load of 15 μN over 10 seconds, and held in that state for 5 seconds. The indenter is pressed into the area near the center in the thickness direction of the coating layer, where the cross section of the coating layer is exposed. The load is then removed over 10 seconds. This provides the maximum load Pmax, the contact projected area A at maximum depth, and the load-displacement curve. Unless otherwise specified, the measurement is performed in an environment of 50% relative humidity and 23°C. Measurements are performed at five or more points on the same cross section, and the indentation hardness and composite modulus are each recorded as the arithmetic average of the values of five points measured with good reproducibility. Further detailed measurement conditions are described in the examples.

When the laminate is heat sterilized, the coating layer needs to have a certain degree of hardness to prevent destruction of the vapor-deposited film due to thermal shrinkage of the OPP substrate during heat sterilization. On the other hand, during lamination processing of the packaging material, the OPP substrate is stretched by tension, which also causes destruction of the vapor-deposited film and a decrease in barrier properties; however, this decrease in barrier properties can be prevented by imparting appropriate flexibility to the coating layer.

The inventors have discovered a range of elastic modulus and indentation hardness suitable for heat sterilization treatment applications such as retort treatment for the coating layer that constitutes the mono-material packaging material, which is a laminate of polypropylene films, and have found a laminate that can suppress a decrease in barrier properties even after "heat sterilization treatment" after "lamination."

As a result, the laminate after heat sterilization has an oxygen transmission rate of 10.0 cc/( ^m2 ·day·atm) or less, preferably 5.0 cc/(m2·day·atm) or less, particularly preferably 2.0 cc/( ^m2 ·day·atm) or less, and most preferably 1.0 cc/( ^m2 ·day·atm) or ^less at 23°C and 90% RH according to JIS K 7126-2. In addition, the water vapor transmission rate after heat sterilization at 40°C and 100% RH according to JIS K 7129 B method is preferably less than 3.0 g/( ^m2 ·day), more preferably 2.0 g/( ^m2 ·day) or less. In this way, a laminate with high gas barrier properties can be obtained even after retort treatment.

The composite elastic modulus and indentation hardness of the coating layer can be adjusted, for example, by adjusting the composition of the coating layer and the drying temperature during coating layer formation.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these descriptions in any way. First, the barrier films according to Examples 1 to 15 and Comparative Examples 1 to 6 were manufactured using the film-forming apparatus 10, which is the film-forming apparatus described in this embodiment, and the film-forming method and coating layer formation process. The pretreatment conditions, deposition conditions, etc. are summarized in Tables 1 and 2.

Example 1
The polypropylene base material for substrate 1 was a 20 μm-thick biaxially oriented polypropylene film (the first layer, which was the surface facing the deposition surface, was a 1.0 μm-thick layer made of a copolymer of propylene, ethylene and butene, the second layer, which was the surface opposite the deposition surface, was a 1.0 μm-thick layer made of a copolymer of propylene, ethylene and butene, the surface of the first layer was corona-treated, and the third layer (middle layer) was a homopolypropylene with a thickness of 18 μm).

Next, a coating liquid for forming an anchor coat layer, which is a mixture of a hydroxyl-containing (meth)acrylic resin and tolylene diisocyanate, is applied by a direct gravure method onto the first layer of the substrate 1 as a base layer, and then dried to form an anchor coat layer with a thickness of 0.2 μm.

After the anchor coat layer was formed, the film was rewound in a humidity control process at 25°C and 50% RH, and then stored at 25°C and 50% RH for 3 days to control the humidity.

In the film formation process, a vapor deposition film containing aluminum oxide was formed by vacuum vapor deposition using a resistive heating type (RH in Table 1) evaporation mechanism 24 as shown in FIG. 6. Specifically, while aluminum metal wire was supplied into the boat 24b as the vapor deposition material, the vapor deposition material in the boat 24b was heated using the resistive heating type evaporation mechanism 24, and the aluminum was evaporated so that it reached the surface of the substrate 1, and a vapor deposition film was formed on the surface of the substrate 1 while supplying oxygen.

As the plasma supply mechanism 50, a hollow cathode 51 as shown in FIG. 6 and anodes (not shown) arranged on both sides of the width direction of the substrate 1 as viewed from the boat 24b and facing the opening of the hollow cathode 51 were used. A plasma raw material gas (argon gas) was supplied to the hollow cathode 51, discharged to excite plasma, and the plasma was drawn between the surface of the substrate 1 and the evaporation mechanism 24 by the opposing anode, thereby performing plasma assist during deposition. The conditions for plasma assist were argon gas supply to the hollow cathode of 80 sccm, anode current of 48 A, and anode voltage of 19 V. The cold trap was not operated, and no plasma post-treatment process was performed after the plasma assist process during deposition.

By the above method, a vapor deposition film was laminated on the substrate 1. The conveying speed was 600 m/min, and the thickness of the vapor deposition film was 8.9 nm. The light transmittance at a wavelength of 366 nm measured in-line after vapor deposition was set to 100% based on the transmittance in a state where the substrate 1 was pretreated and no vapor deposition was performed. Vapor deposition was then started, and the oxygen supply volume was feedback-controlled so that the light transmittance was 99.7%. The pressure during vapor deposition was 1.1 Pa.

The barrier film roll that had undergone the above-mentioned film formation process was aged for three days at 55°C and 50% RH.

Further, a coating layer was laminated on the deposition film in the coating layer forming process. As a water-soluble polymer, polyvinyl alcohol having a saponification degree of 99% or more and a polymerization degree of 2400 was mixed with a liquid of water and isopropyl alcohol in a ratio of 95/5 to obtain a solution A adjusted to a solid content of 4%. Water, isopropyl alcohol, and 1N hydrochloric acid were mixed in a ratio of 65/34/1 to obtain an adjusted solution B. As a metal alkoxide, tetraethoxysilane was prepared as solution C. A liquid obtained by adjusting the ratio of solution B and solution C and mixing the liquid obtained by adjusting the ratio of solution A and solution D was used as a barrier coating agent. The ratio of solution B to solution C and the ratio of solution A to solution D were adjusted so that the solid content of the barrier coating agent after mixing was 7%, and the mass of tetraethoxysilane converted to _SiO2 was 2.5 relative to the solid content of PVA. This barrier coating agent was used as solution X.

The barrier coating agent prepared above was applied onto the vapor deposition film by the direct gravure method. It was then dried at 100°C to form a coating layer with a dry thickness of 300 nm. It was then aged for 7 days at 55°C and 50% RH to form a coating layer, producing the barrier film of Example 1.

Example 2
A barrier film of Example 2 was produced in the same manner as in Example 1, except that plasma assistance was not performed in the film formation process.

Example 3
A barrier film of Example 3 was produced in the same manner as in Example 2, except that in the film-forming step, the conveying speed was 670 m/min, the thickness of the deposited film was 8.0 nm, the light transmittance was 94.0%, and the pressure was 0.3 Pa.

Example 4
A barrier film of Example 4 was produced in the same manner as in Example 3, except that the light transmittance was 88.0% and the pressure was 0.2 Pa in the film-forming process.

Example 5
The barrier film of Example 5 was produced in the same manner as in Example 1, except that in the humidity adjustment step, the raw roll was rewound in an atmosphere of 30°C and 60% RH and then stored at 30°C and 60% RH for 3 days, and the aging treatment after the film formation step was performed at 60°C and 50% RH for 4 days.

Example 6
The barrier film of Example 6 was produced in the same manner as in Example ₃ , except that in the coating layer formation step, the ratio of solution B to solution C and the ratio of solution A to solution D were adjusted so that the mass of tetraethoxysilane converted into SiO2 relative to the solid content of PVA was 2.25.

(Example 7)
The barrier film of Example 7 was produced in the same manner as in Example ₃ , except that in the coating layer formation step, the ratio of solution B to solution C and the ratio of solution A to solution D were adjusted so that the mass of tetraethoxysilane converted into SiO2 relative to the solid content of PVA was 2.75.

(Example 8)
The barrier film of Example ₈ was produced in the same manner as in Example 3, except that in the coating layer formation step, the ratio of solution B to solution C and the ratio of solution A to solution D were adjusted so that the mass of tetraethoxysilane converted into SiO2 relative to the solid content of PVA was 3.0.

(Example 9)
The barrier film of Example ₉ was produced in the same manner as in Example 3, except that in the coating layer formation step, the ratio of solution B to solution C and the ratio of solution A to solution D were adjusted so that the mass of tetraethoxysilane converted into SiO2 relative to the solid content of PVA was 3.5.

(Example 10)
The barrier film of Example 10 was produced in the same manner as in Example 3, except that solution Y was used in the coating layer formation process. When mixing solutions B and C, 5% of glycidoxypropyltrimethoxysilane was added relative to the weight of tetraethoxysilane, and then the ratios of solutions B and C and solutions A and D were adjusted to mix so that the solid content was 7% and the mass of tetraethoxysilane converted to _SiO2 relative to the solid content of PVA was 2.5, to form a coating layer, and this mixed barrier coating agent was designated solution Y.

Example 11
The barrier film of Example 11 was produced in the same manner as in Example ₁₀ , except that in the coating layer formation step, the ratio of solution B to solution C and the ratio of solution A to solution D were adjusted so that the mass of tetraethoxysilane in terms of SiO2 relative to the solid content of PVA was 3.5.

Example 12
The barrier film of Example 12 was produced in the same manner as in Example 3, except that solution Z was used in the coating layer formation step. When mixing solutions B and C, 8% of 1,3,5-tris(3-trialkoxysilylpropyl)isocyanurate was added relative to the weight of tetraethoxysilane, and the ratios of solutions B and C and solutions A and D were adjusted so that the coating layer had a solid content of 7% and the mass of tetraethoxysilane converted to _SiO2 relative to the solid content of PVA was 3.5, to produce a barrier coating agent called solution Z.
Example 13
A barrier film of Example 13 was produced in the same manner as in Example 3, except that the aging treatment after the coating layer formation step was not performed.

(Example 14)
The barrier film of Example 14 was produced in the same manner as in Example ₁₃ , except that in the coating layer formation step, the ratio of solution B to solution C and the ratio of solution A to solution D were adjusted so that the mass of tetraethoxysilane in terms of SiO2 relative to the solid content of PVA was 3.5.

(Example 15)
The substrate 1 was a substrate (total thickness 20 μm) that was stretched after multilayer coextrusion of a polyamide resin as the underlayer, a modified polypropylene as the first layer, a homopolypropylene as the third layer, and a layer made of a copolymer of propylene and ethylene as the second layer. The underlayer had a thickness of 0.6 μm, the first layer had a thickness of 1.5 μm, and the second layer had a thickness of about 0.6 μm. Nylon 6 was used as the polyamide resin.

Then, as a humidity adjustment process, the rolled raw material was rewound in an atmosphere of 25°C and 50% RH, and then stored at 25°C and 50% RH for 3 days to adjust the humidity.

The gas barrier film of Example 15 was produced in the same manner as in Example 3, except that in the film formation process of Example 3, the following pretreatment process was carried out.
<Pretreatment process>
The surface of the substrate 1 was subjected to plasma pretreatment using the plasma pretreatment mechanism 11B shown in Figures 2 and 3. Specifically, first, a plasma forming gas was supplied to the plasma pretreatment chamber 12B using the plasma raw material gas supply unit, while the air pressure in the plasma pretreatment chamber 12B was adjusted using the reduced pressure chamber 12. Next, a voltage was applied between the pretreatment roller 20 and the electrode unit 21 to generate plasma, and the surface of the substrate 1 was subjected to plasma pretreatment. The plasma pretreatment was performed under the following conditions.
<Pretreatment conditions>
Conveying speed of substrate: 600 m/min
High frequency power output: 4kW
High frequency power supply frequency: 40 kHz
Plasma intensity: 550 W·sec/ ^m2
Plasma forming gas: oxygen 100 (sccm), argon 1000 (sccm)
Magnetic forming means: 1000 gauss permanent magnet Voltage applied between pretreatment drum and plasma supply nozzle: 420 V
Pressure in pretreatment compartment: 2.0×10 ⁻¹ Pa

(Comparative Example 1)
A barrier film of Comparative Example 1 was produced in the same manner as in Example 1, except that in the film formation process, a cold trap was operated and the plasma assist conditions were an anode current of 154 A and an anode voltage of 18 V.

(Comparative Example 2)
A barrier film of Comparative Example 2 was produced in the same manner as in Comparative Example 1, except that in the film formation process, the plasma assist conditions were an anode current of 140 A and an anode voltage of 16 V.

(Comparative Example 3)
The barrier film of Comparative Example 3 was produced in the same manner as in Example 5, except that an aging treatment after the film formation step was carried out at 60°C and 80% RH for 5 days, and a sheet of approximately 210 mm x 300 mm cut from the roll was coated with the barrier coating agent using an applicator.
(Comparative Example 4)
A barrier film of Comparative Example ₄ was produced in the same manner as in Example 3, except that in the coating layer formation step, the ratio of solution B to solution C and the ratio of solution A to solution D were adjusted so that the mass of tetraethoxysilane converted into SiO2 relative to the solid content of PVA was 1.5.
(Comparative Example 5)
A barrier film of Comparative Example 5 was produced in the same manner as in Example ₃ , except that in the coating layer formation step, the ratio of solution B to solution C and the ratio of solution A to solution D were adjusted so that the mass of tetraethoxysilane converted into SiO2 relative to the solid content of PVA was 4.0.
(Comparative Example 6)
A barrier film of Comparative Example 6 was produced in the same manner as in Example ₃ , except that solution Z was used in the coating layer formation step, and the ratio of solution B to solution C and the ratio of solution A to solution D were adjusted so that the mass of tetraethoxysilane converted into SiO2 relative to the solid content of PVA was 4.0.

[Acquisition and analysis of XAFS spectra]
XAFS spectra were obtained under the following measurement conditions for the barrier films of Examples 1 to 15 and Comparative Examples 1 to 6. The result of Example 2 is shown in Figure 9. The vertical axis in the figure represents the intensity of the generated fluorescent X-rays (shown as absorption intensity (a.u) in the figure), and the horizontal axis represents the light (or X-ray) energy (eV).

<XAFS spectrum acquisition>
・Line used: Aichi Synchrotron Light Center BL1N2
Acceleration energy: 1.2 GeV
-Beam size: horizontal 1.0 mm x vertical 1.0 mm
Incident angle to sample: 22.5° (vertical direction to sample is 0°)
・Inlet slit: 30 μm
Exit slit: 30 μm
Measurement method: partial fluorescence yield method Energy range (Al K-edge): 1500-1700 eV
・Energy Step:
1500-1550eV: 2.0eV/step
1550-1555eV: 1.0eV/step
1555-1575eV: 0.2eV/step
1575-1600eV: 0.5eV/step
1600-1680eV: 1.0eV/step
1680-1700eV: 2.0eV/step
(Storage time: all 10s/point)
Energy calibration: Energy calibration by Au 4f 7/2 of Au plate (calibrated by subtracting the theoretical value of 1500 eV from the actual value)

<XAFS Spectral Analysis>
Peak Separation Method The intensity values were normalized so that the absorption spectrum intensity value at an absorbed X-ray energy value of 1557 eV was 0 and the absorption spectrum intensity value at an absorbed X-ray energy value of 1590 eV was 1.

The normalized data points from 1555 eV to 1575 eV and from 1598 eV to 1602 eV were extracted, and the above f(x) function was fitted to obtain each coefficient. However, the constraints _k1 = _k2 , _K1 = _X1 , and _K2 = _X2 were included. The fitting was performed by the least squares method. In this case, the least squares function of the Python scipy library was used to obtain the initial values of the coefficients by giving the values shown in the table below. The symbols of the above functions are defined as follows.
M _i : weighting factor of Gaussian function and Lorentzian function in the i-th absorption peak X _i : peak center in the i-th absorption peak h _i : peak intensity factor in the i-th absorption peak β _i : peak width factor in the i-th absorption peak k _j : baseline intensity factor in the j-th baseline K _j : half-point of baseline intensity in the j-th baseline

Figure 10 shows the results of peak separation of the XAFS spectrum of Example 2. Similarly, Figure 11 shows the analysis results of separating the XAFS peaks of Example 3, Figure 12 shows the analysis results of separating the XAFS peaks of Comparative Example 1, and Figure 13 shows the analysis results of separating the XAFS peaks of Comparative Example 2.

Experiment is the measured XAFS spectrum, Fit. Peak1 is the isolated intensity peak near 1566 eV, Fit. Peak2 is the isolated intensity peak near 1568 eV, and Fit. Peak3 is the isolated intensity peak near 1572 eV. From this, the XAFS peak top ratio P = (intensity peak top near 1572 eV) / (intensity peak top near 1566 eV) was calculated, and the results are shown in Table 4 for the barrier films of Examples 1 to 15 and Comparative Examples 1 to 6.

[Elemental analysis of coating layer]
The narrow spectrum of each element was measured using an X-ray photoelectron spectroscopy analyzer (XPS) for the coating layer surfaces of the barrier films of Examples 1 to 15 and Comparative Examples 1 to 6. The measured surfaces were then etched under the conditions described below to expose new measurement surfaces. The narrow spectrum of each element was measured for the exposed measurement surfaces under the same conditions.
For each narrow spectrum of C1s and Si2p, the background was subtracted by the Shirley method using analysis software to obtain the integrated intensity (area) of the peak of each element. The obtained integrated intensity (area) was used to calculate the ratio of each element (element %). The Si/C ratio was calculated from the ratio of each element after etching for 60 seconds x 2 times, and is shown in Table 4.
<X-ray photoelectron spectrum measurement conditions>
Equipment: Shimadzu Corporation ESCA3400
X-ray source: MgKα
Emission current: 20mA
Acceleration voltage: 10 kV
Resolution: Low
Measurement area: approx. 6 mm diameter
<Etching conditions>
Ion species: Ar ⁺
Ar gas introduction pressure: 2.0×10 ⁻² Pa
Emission current: 30mA
Acceleration voltage: 0.3 kV
Etching time: 60 seconds x 2 times

<Evaluation of color unevenness on the outer edge of barrier film>
A visual appearance inspection was carried out from the end face of the roll for each of the barrier films of Examples 1 to 15 and Comparative Examples 1 to 6. The results are shown in Table 5.
Here, "visual appearance at end face" is an evaluation of color unevenness by visual inspection when viewed from the end face side (side surface) of the roll. When viewed from the end face side of the barrier film roll, the barrier film was sampled from the dark color area (A) and the light color area (B), and one sheet of the barrier film from the dark color area (A) was placed on a standard white board with the film surface facing up, and measured using a Konica Minolta spectrophotometer CM-600d under the conditions of SCI (including regular reflection light), 10° field of view, and D65 light source. The light color area (B ⁾ was also measured in the same manner, and the color difference between the dark color area (A) and the light color area (B) was calculated from the measured L*, a ^* , and b ^* values. It was confirmed that when the color difference for one barrier film was 0.3 or more, it was judged by visual appearance inspection that there was strong color unevenness when viewed from the end face of the roll.

<Preparation of Laminate>
For the barrier films of Examples 1 to 15 and Comparative Examples 1 to 6, the surface on the coating layer 130 side was bonded to a second biaxially oriented polypropylene film 140 (thickness: 20 μm) by dry lamination using a polyurethane-based two-component curing solvent-based adhesive via a second adhesive layer 162. Furthermore, the surface of the barrier film opposite the coating layer 130 was bonded to a sealant layer (unstretched polypropylene film, 60 μm) by dry lamination using a two-component curing solvent-based adhesive via a first adhesive layer 161 to produce the laminate of Example 1.

<Retort processing>
The laminates of Examples 1 to 15 and Comparative Examples 1 to 6 were subjected to a retort treatment at 121° C. for 30 minutes and a high retort treatment at 135° C. for 30 minutes.

<Measurement of Barrier Properties of Barrier Films and Laminates>
The water vapor permeability and oxygen permeability were measured for the barrier films and laminates using the same of Examples 1 to 15 and Comparative Examples 1 to 6. The results are shown in Tables 5 and 6.

The oxygen transmission rate (cc/( ^m2 ·day·atm), indicated as "OTR" in the table) was measured using an oxygen transmission rate measuring device (manufactured by Mocon, product name "OX-TRAN 2/20") under the measurement conditions of 23°C and 90% RH in accordance with JIS K 7126-2.

The water vapor transmission rate (g/( ^m2 ·day), indicated as "WVTR" in the table) was measured using a water vapor transmission rate measuring device (manufactured by Mocon, product name "PERMATORAN-W 3/31") under measurement conditions of 40°C and 100% RH in accordance with JIS K 7129 B method.

<Measurement of composite elastic modulus and indentation hardness of coating layer>
For the laminates of Examples 1 to 15 and Comparative Examples 1 to 6, the composite elastic modulus (GPa) and indentation hardness (GPa) of the coating layer of the laminates after heat sterilization treatment were measured under the following conditions. The results are shown in Tables 5 and 6.
Measurement device: HYSITRON TI-950 Triboindenter Measurement location: from the cross-section side of the coating layer Measurement mode: indentation Indenter: cubecorner indenter, TI-0037
Number of data points: 200 points/second
Measurement profile 0→10sec: 0→15μN
10→15sec: 15μN
15→25sec: 15→0μN

From Tables 5 and 6, it can be seen that the laminate using the barrier film using the polypropylene base material according to this embodiment, in which the peak top ratio P obtained from the XAFS spectrum is 1.05 or more and less than 1.60, has high barrier properties and reduced color unevenness after retort treatment.

It can also be seen that a laminate using a polypropylene base material with a composite elastic modulus of 5.0 GPa or more and 8.5 GPa or less and an indentation hardness of 0.9 GPa or more and 1.7 GPa or less has excellent oxygen barrier properties after retort treatment.

110 (First) polypropylene substrate 115 Undercoat layer 120 Vapor deposition film 130 Coating layer 140 Second polypropylene substrate 150 Sealant layer 161 First adhesive layer 162 Second adhesive layer 100, 200 Laminate 100A Barrier film 10 Film-forming device P Plasma X Rotating shaft 11A Substrate transport mechanism 11B Plasma pretreatment mechanism 11C Film-forming mechanism 12 Decompression chamber 12A Substrate transport chamber 12B Plasma pretreatment chamber 12C Film-forming chamber 13 Unwinding rollers 14a-d Guide roll 15 Winding roller 20 Pretreatment roller 21 Electrode section 23 Magnetic field forming section 23a First surface 23b Second surface 231 First magnet 231c First axial portion 232 Second magnet 232c Second axial portion 232d Connection portion 24 Evaporation mechanism 24b Boat 25 Film-forming roller 31 Power supply wiring 32: Power sources 35a to 35c: Partition wall 50: Plasma supply mechanism 51: Hollow cathode 61: Vapor deposition material supply unit 63: Aluminum vapor

Claims (8)

A barrier film comprising a polypropylene substrate, a base layer, an aluminum oxide vapor deposition film, and a coating layer having barrier properties, laminated in this order,
the coating layer is a cured product of a resin composition containing an alkoxysilane and a hydroxyl group-containing water-soluble resin,
the coating layer has a ratio of silicon atoms to carbon atoms (Si/C) measured by X-ray photoelectron spectroscopy (XPS) of 1.30 or more and 1.65 or less;
The aluminum oxide vapor-deposited film has a peak top ratio P, defined as follows, of 1.05 or more and less than 1.60 when X-ray absorption fine structure analysis is performed from the coating layer surface side of the barrier film.
P = (peak intensity top near 1572 eV) / (peak intensity top near 1566 eV) The barrier film according to claim 1, wherein the undercoat layer is an anchor coat layer formed on the polypropylene substrate. The barrier film according to claim 1, wherein the undercoat layer is a surface resin layer containing a polyamide resin formed on the polypropylene substrate. the polypropylene base material has at least a first layer and a second layer as two surface layers, the first layer being formed on the undercoat layer side;
the first layer comprises a copolymer of propylene and another monomer;
The undercoat layer is the anchor coat layer,
3. The barrier film according to claim 2 , wherein the first layer of the polypropylene base material, the anchor coat layer, the aluminum oxide vapor-deposited film, and the coating layer having barrier properties are laminated in this order. the polypropylene base material has at least a first layer and a second layer as two surface layers, the first layer being formed on the undercoat layer side;
the first layer comprises modified polypropylene;
the undercoat layer is the surface resin layer containing the polyamide resin,
4. The barrier film according to claim 3 , wherein the first layer of the polypropylene base material, the surface resin layer containing the polyamide resin, the aluminum oxide vapor-deposited film, and the coating layer having barrier properties are laminated in this order. the polypropylene base material has at least a first layer and a second layer as two surface layers, the second layer being formed on a surface opposite to the undercoat layer side,
the second layer comprises a copolymer of propylene and another monomer;
2. The barrier film according to claim 1, wherein the first layer of the polypropylene base material, the undercoat layer, the aluminum oxide vapor-deposited film, and the coating layer having barrier properties are laminated in this order. A heat-sterilized laminate comprising the barrier film according to any one of claims 1 to 6 and a sealant layer, the laminate being used for a packaging bag for containing retort food or boiled food,
A laminate, wherein the coating layer of the laminate has a composite elastic modulus and an indentation hardness, as measured by a nanoindentation method from a cross-section of the coating layer, of which the composite elastic modulus is 5.0 GPa or more and 8.5 GPa or less, and the indentation hardness is 0.9 GPa or more and 1.7 GPa or less. A packaging product comprising the laminate of claim 7 .

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