JP7718038B2 - Barrier film, laminate using said barrier film, and packaged product using said laminate - Google Patents

Description

The present invention relates to a barrier film, a laminate using the barrier film, and a packaging product using the laminate.

Laminate films, which have a film formed on a substrate such as a long film or sheet made of plastic, are currently used in a variety of applications. For example, barrier laminate films have been developed that have a barrier layer made of a thin film such as aluminum oxide on a plastic film, providing barrier properties against oxygen and water vapor.

For example, Patent Document 1 discloses a method for manufacturing a barrier film comprising a thin aluminum oxide film, in which moisture contained in the reaction space where the oxidation reaction between oxygen gas and evaporated aluminum occurs is removed during deposition, thereby suppressing the production of aluminum hydroxide and improving hot water resistance.

Japanese Patent Application Laid-Open No. 2016-203427

The present invention aims to provide a barrier film having an aluminum oxide vapor-deposited film and exhibiting even higher barrier properties, as well as a laminate using the barrier film.

As a result of extensive research into solving the above problems, the inventors discovered that by focusing on the distribution of aluminum oxide and aluminum hydroxide in an aluminum oxide vapor-deposited film, it is possible to obtain a barrier film with even higher barrier properties, leading to the completion of the present invention.

Aluminum hydroxide has a high affinity for water molecules, so water molecules penetrate into the aluminum hydroxide film, reducing its barrier properties against water vapor. The method described in Patent Document 1 reduces the number of hydroxyl groups (hydrogen atoms) throughout the aluminum oxide film.

However, according to the inventors' findings, the growth of the aluminum oxide vapor-deposited film on the aluminum hydroxide surface proceeds in two dimensions, resulting in the formation of a denser aluminum oxide vapor-deposited film. In other words, the aluminum oxide film deposited on the aluminum hydroxide surface exhibits superior barrier properties against oxygen and water vapor compared to aluminum oxide deposited directly on the surface of a plastic film.

Therefore, to achieve a barrier film with high barrier performance, an alumina hydroxide region is formed near the interface between the plastic film and the aluminum vapor deposition, and an aluminum oxide region is primarily formed on top of this alumina hydroxide region, thereby achieving even higher barrier properties.

Specifically, the present invention provides the following:

(1) A barrier film comprising a substrate and an aluminum oxide vapor-deposited film laminated in this order,
When the aluminum oxide vapor-deposited film is etched from the vapor-deposited film surface side of the barrier film by time-of-flight secondary ion mass spectrometry (TOF-SIMS), intensities derived from elemental bonds Al ₂ O ₃ and elemental bonds Al ₂ O ₄ H are detected,
A barrier film, wherein the aluminum oxide vapor-deposited film has an intensity ratio of the elemental bond Al ₂ O ₄ H to the elemental bond Al ₂ O ₃ (Al ₂ O ₄ H/Al ₂ O ₃ ) of 0.30 or less, detected at a depth position of 1/3 from the surface of the vapor-deposited film in the film thickness direction.

(2) The barrier film according to (1), wherein the intensity derived from the element bond Al ₂ O ₄ H has a maximum peak, and the maximum peak is present at a depth position of 55% to 95% from the surface of the vapor-deposited film.

(3) The aluminum oxide vapor-deposited film has an infrared absorption spectrum from the vapor-deposited film surface side of the barrier film,
The barrier film according to (1) or (2), wherein an absorption peak originating from an Al—O bond is present in the range of 940 cm ⁻¹ to 960 cm ⁻¹ .

(4) The barrier film according to (3), wherein the ratio of the absorption intensity of the absorption peak at 3,350 cm ⁻¹ or ^more and 3,550 cm ⁻¹ or less, which is attributable to an OH bond, to the absorption intensity of the absorption peak at 940 cm ⁻¹ or more and 960 cm −1 or less, which is attributable to an Al—O bond, is 0.20 or less.

(5) A laminate comprising the barrier film described in any one of (1) to (4) and a sealant layer.

(6) A packaging product comprising the laminate described in (5).

The barrier film of the present invention has even higher barrier properties.

FIG. 1 is a cross-sectional view showing an example of a barrier film according to the present embodiment. 1 is a diagram illustrating 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. FIG. 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. 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. 1 is a cross-sectional view showing an example of a laminate including a barrier film according to an embodiment of the present invention. FIG. 1 is a graph analysis diagram showing the measurement results of the barrier film of Example 1 by TOF-SIMS. FIG. 1 is a graph analysis diagram showing the measurement results of the barrier film of Example 2 by TOF-SIMS. FIG. 10 is a graph analysis diagram showing the measurement results of the barrier film of Example 3 by TOF-SIMS. FIG. 10 is a graph analysis diagram showing the measurement results of the barrier film of Example 4 by TOF-SIMS. FIG. 10 is a graph analysis diagram showing the measurement results of the barrier film of Example 5 by TOF-SIMS. FIG. 1 is a graph analysis diagram showing the measurement results of the barrier film of Comparative Example 1 by TOF-SIMS. FIG. 10 is a graph analysis diagram showing the measurement results of the barrier film of Comparative Example 2 by TOF-SIMS. 1 is a graph showing the results of FT-IR measurements of barrier films of Examples and Comparative Examples. 1 is a graph showing the results of FT-IR measurements of barrier films of Examples and Comparative Examples. FIG. 1 is a plan view showing an example of a loop stiffness measuring device. 17 is a cross-sectional view of the loop stiffness measuring device of FIG. 16 taken along line VV. FIG. 10 is a diagram illustrating a process of attaching a test piece to a loop stiffness measuring instrument. FIG. 10 is a diagram illustrating a step of forming a loop portion in a test piece. FIG. 10 is a diagram illustrating a process of applying a load to a loop portion of a test piece. FIG. 10 is a diagram illustrating a process of applying a load to a loop portion of a test piece.

Specific embodiments of the present invention are described in detail below, but the present invention is not limited to the following embodiments and can be implemented with appropriate modifications within the scope of the invention. Furthermore, in this specification, the expression "X to Y" (X and Y are arbitrary numbers) means "greater than or equal to X and less than or equal to Y."

Figure 1 is a cross-sectional view showing an example of a barrier film according to this embodiment. A barrier film manufactured using the film-forming apparatus according to this embodiment includes a substrate 1 and a vapor-deposited film 2, such as barrier film A shown in Figure 1. In the example shown in Figure 1, the vapor-deposited film 2 is located on one side of the substrate 1. Also, in the example shown in Figure 1, the vapor-deposited film 2 is located on the surface of the barrier film.

In this specification, "layered in this order" means that the substrate and the aluminum oxide vapor-deposited film are layered in this order, and other layers, such as a primer, may be layered between these layers.

The following describes each layer that makes up barrier film A.

[Base material]
The substrate 1 is a layer mainly containing a resin. There are no particular limitations on the resin, and known resin films or sheets can be used. For example, resin films containing polyester resins such as polyethylene terephthalate resins, polybutylene terephthalate resins, and polyethylene naphthalate resins, polyamide resins, and polyolefin resins such as polymers and copolymers of α-olefins such as polyethylene and polypropylene can be used.

Of these resins, polyester resins are preferably used, and among polyester resins, polyethylene terephthalate resins and polybutylene terephthalate resins are preferably used. The polyester film used as substrate 1 may be stretched in a predetermined direction. In this case, the polyester film may be a uniaxially stretched film stretched in one predetermined direction, or a biaxially stretched film stretched in two predetermined directions. For example, when a film made of polyethylene terephthalate is used as substrate 1, a biaxially stretched polyethylene terephthalate film can be used.

The thickness of the polyester film used as the substrate 1 as described above is not particularly limited, as long as it can be used for pretreatment and film formation when forming the vapor-deposited film 2 using the film-forming device described below. However, from the perspective of flexibility and shape retention, a thickness in the range of 6 μm to 100 μm is preferred. When the polyester film thickness is within this range, it is easy to bend and does not tear during transport, and it is easy to handle in the film-forming device used to manufacture a barrier film having a vapor-deposited film 2 with improved adhesion.

In addition to conventionally known polyethylene terephthalate (PET) films, biomass PET films, recycled PET films, and high-stiffness PET films (tough PET films) may also be used as the substrate 1.

<Biomass PET film>
The biomass PET film is a resin film containing a biomass-derived polyester, in which the diol unit is ethylene glycol derived from biomass and the dicarboxylic acid unit is dicarboxylic acid derived from fossil fuels.

Because biomass-derived ethylene glycol has the same chemical structure as conventional fossil fuel-derived ethylene glycol, polyester film synthesized using biomass-derived ethylene glycol is comparable to conventional fossil fuel-derived polyester film in terms of physical properties, such as mechanical characteristics. Therefore, substrates using biomass-derived polyester film have a layer made of carbon-neutral materials, which allows for a reduction in the amount of fossil fuel used compared to substrates made from raw materials obtained from conventional fossil fuels, thereby reducing the environmental burden.

Biomass-derived ethylene glycol is made from ethanol (biomass ethanol) produced from biomass such as sugarcane or corn. For example, biomass-derived ethylene glycol can be obtained by converting biomass ethanol to ethylene oxide using a conventional method, or by producing ethylene glycol via that method. Alternatively, commercially available biomass ethylene glycol may be used; for example, biomass ethylene glycol available from India Glycoal Limited is suitable.

The dicarboxylic acid unit of the polyester uses a dicarboxylic acid derived from a fossil fuel. Examples of the dicarboxylic acid include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and derivatives thereof. Examples of aromatic dicarboxylic acids include terephthalic acid and isophthalic acid, and examples of aromatic dicarboxylic acid derivatives include lower alkyl esters of aromatic dicarboxylic acids, specifically methyl esters, ethyl esters, propyl esters, and butyl esters. Among these, terephthalic acid is preferred, and examples of aromatic dicarboxylic acid derivatives include dimethyl terephthalate.

Biomass-derived polyesters can be obtained by conventionally known methods of polycondensing diol units and dicarboxylic acid units. Specifically, they can be produced by a common melt polymerization method in which an esterification reaction and/or transesterification reaction between the dicarboxylic acid component and the diol component is carried out, followed by a polycondensation reaction under reduced pressure, or by a known solution heating dehydration condensation method using an organic solvent.

The resin composition constituting the resin film containing biomass-derived polyester may be composed solely of biomass-derived polyester, or may contain fossil fuel-derived polyester in addition to biomass-derived polyester. Fossil fuel-derived polyester consists of diol units and dicarboxylic acid units, and is obtained by a polycondensation reaction using ethylene glycol, a fossil fuel-derived diol, as the diol unit and a fossil fuel-derived dicarboxylic acid as the dicarboxylic acid unit.

The resin in the resin composition constituting the resin film containing biomass-derived polyester may contain recycled polyester in addition to the biomass-derived polyester. The recycled polyester may be recycled from biomass-derived polyester or recycled from fossil fuel-derived polyester.

The resin composition that constitutes the resin film containing biomass-derived polyester can contain various additives. Examples of additives include plasticizers, UV stabilizers, color inhibitors, matting agents, deodorizers, flame retardants, weather resistance agents, antistatic agents, friction reducers, mold release agents, antioxidants, ion exchange agents, and color pigments. The additives are preferably contained in the entire resin composition containing PET in an amount of 5% by mass to 50% by mass, and preferably 5% by mass to 20% by mass.

Resin films containing biomass-derived polyester can be formed, for example, by film formation using the T-die method. Specifically, after drying the above-mentioned PET, the resin composition is fed into a melt extruder heated to a temperature above the melting point of PET (Tm) to Tm + 70°C. The resin composition is melted and extruded into a sheet through a die such as a T-die. The extruded sheet is then rapidly cooled and solidified using a rotating cooling drum or similar to form a film. Melt extruders that can be used include single-screw extruders, twin-screw extruders, vent extruders, and tandem extruders, depending on the purpose. Hereinafter, the melting point and glass transition temperature may be referred to as Tm and Tg, respectively, as necessary.

Atmospheric carbon dioxide contains a certain percentage of 14C (105.5 pMC). Therefore, the 14C content in plants that grow by absorbing atmospheric carbon dioxide, such as corn, is known to be approximately 105.5 pMC. It is also known that fossil fuels contain very little 14C. Therefore, the percentage of biomass-derived carbon can be calculated by measuring the percentage of 14C in the total carbon atoms in a polyester. In this specification, "biomass ratio" refers to the mass ratio of biomass-derived components. Taking PET (polyethylene terephthalate) as an example, PET is a polymer of ethylene glycol containing two carbon atoms and terephthalic acid containing eight carbon atoms in a 1:1 molar ratio. If only biomass-derived ethylene glycol is used, the mass ratio of biomass-derived components in PET is 31.25%, resulting in a biomass ratio of 31.25% (molecular weight derived from biomass-derived ethylene glycol / molecular weight of one polyester polymerization unit = 60 ÷ 192). Furthermore, the mass ratio of biomass-derived components in the fossil fuel-derived polyester is 0%, and the biomass content of the fossil fuel-derived polyester is 0%. In the present invention, the biomass content in the resin film containing biomass-derived polyester is preferably 5.0% or more, more preferably 10.0% or more, and preferably 30.0% or less.

The resin film containing biomass-derived polyester is preferably biaxially stretched. Biaxial stretching can be performed by conventional methods. For example, the film extruded onto the cooling drum as described above is subsequently heated by roll heating, infrared heating, or the like, and stretched in the machine direction to form a machine-stretched film. This stretching is preferably performed using the difference in peripheral speed between two or more rolls. Machine-stretching is usually performed at a temperature range of 50 to 100°C. The machine-stretching ratio is preferably 2.5 to 4.2 times, although this depends on the required properties of the film's application. If the stretching ratio is less than 2.5 times, the thickness of the polyester film will become uneven, making it difficult to obtain a good film.

The longitudinally stretched film is then subjected to the sequential processes of transverse stretching, heat setting, and heat relaxation to become a biaxially stretched film. Transverse stretching is usually carried out at a temperature between 50 and 100°C. The transverse stretching ratio is preferably between 2.5 and 5.0 times, depending on the required properties of the application. If it is less than 2.5 times, the film thickness will be uneven, making it difficult to obtain a good film, and if it exceeds 5.0 times, breakage will occur easily during film production.

After transverse stretching, heat setting is performed. The preferred heat setting temperature range is Tg + 70 to Tm - 10°C of the polyester. The heat setting time is preferably 1 to 60 seconds. For applications requiring reduced heat shrinkage, heat relaxation may be performed as needed.

The thickness of the resin film containing biomass-derived polyester varies depending on the application, but is typically about 5 to 500 μm. The breaking strength of the resin film containing biomass-derived polyester is 5 to 40 kgf/mm ² in the MD direction and 5 to 35 kgf/mm ² in the TD direction, and the breaking elongation is 50 to 350% in the MD direction and 50 to 300% in the TD direction. The shrinkage rate when left in a temperature environment of 150°C for 30 minutes is 0.1 to 5%.

Resin films containing biomass-derived polyesters can be used effectively for packaging products such as bags, lids, and laminated tubes, as well as various label materials and molded sheet products. When using resin films containing recycled PET for packaging products, the thickness of the stretched film is preferably 5 to 30 μm.

<Recycled PET film>
The recycled PET film is a resin film containing recycled PET, and includes PET recycled by mechanical recycling. Specifically, it includes PET recycled by mechanical recycling of PET bottles, and this PET contains ethylene glycol as a diol component and terephthalic acid and isophthalic acid as dicarboxylic acid components.

Mechanical recycling generally refers to a method in which collected polyethylene terephthalate resin products, such as PET bottles, are crushed and washed with alkali to remove dirt and foreign matter from the surface of the PET resin products, and then dried at high temperature and reduced pressure for a certain period of time to diffuse and decontaminate contaminants remaining inside the PET resin, removing dirt from the resin products made of PET resin and returning them to PET resin.

Hereinafter, polyethylene terephthalate recycled from PET bottles will be referred to as "recycled polyethylene terephthalate (hereinafter also referred to as recycled PET)," and polyethylene terephthalate that has not been recycled will be referred to as "virgin polyethylene terephthalate (hereinafter also referred to as virgin PET)."

The content of isophthalic acid components in the PET contained in the base material is preferably 0.5 mol% to 5 mol%, and more preferably 1.0 mol% to 2.5 mol%, of the total dicarboxylic acid components that make up the PET. If the content of isophthalic acid components is less than 0.5 mol%, flexibility may not be improved, while if it exceeds 5 mol%, the melting point of the PET may decrease, resulting in insufficient heat resistance.

In addition to the usual PET derived from fossil fuels, PET may also be biomass-derived PET. This biomass-derived PET is PET that uses biomass-derived ethylene glycol as the diol component and fossil fuel-derived dicarboxylic acid as the dicarboxylic acid component.

PET used in PET bottles can be obtained by a conventionally known method of polycondensing the diol component and dicarboxylic acid component described above. Specifically, it can be produced by a common melt polymerization method in which esterification and/or transesterification of the diol component and dicarboxylic acid component is performed, followed by a polycondensation reaction under reduced pressure, or by a known solution heating dehydration condensation method using an organic solvent. The amount of diol component used in producing the PET is essentially equimolar to 100 moles of dicarboxylic acid or its derivative. However, due to distillation during the esterification and/or transesterification and/or polycondensation reaction, an excess of 0.1 mol% to 20 mol% is generally used. Furthermore, the polycondensation reaction is preferably carried out in the presence of a polymerization catalyst. The timing of addition of the polymerization catalyst is not particularly limited, as long as it is before the polycondensation reaction. It may be added when the raw materials are charged or when the pressure reduction begins.

After the PET recycled from PET bottles has been polymerized and solidified as described above, it may be subjected to solid-state polymerization as needed to further increase the degree of polymerization or to remove oligomers such as cyclic trimers. Specifically, solid-state polymerization is carried out by cutting the PET into chips and drying them, then heating them at a temperature of 100°C to 180°C for approximately 1 to 8 hours to pre-crystallize the PET, and then heating them at a temperature of 190°C to 230°C in an inert gas atmosphere or under reduced pressure for 1 to several tens of hours.

The intrinsic viscosity of the PET contained in recycled PET is preferably 0.58 dl/g or more and 0.80 dl/g or less. If the intrinsic viscosity is less than 0.58 dl/g, the mechanical properties required for the PET film as a resin substrate may be insufficient. On the other hand, if the intrinsic viscosity exceeds 0.80 dl/g, productivity in the film production process may be impaired. Note that the intrinsic viscosity is measured in an orthochlorophenol solution at 35°C.

The recycled PET preferably contains recycled PET in a proportion of 50% by mass or more and 95% by mass or less, and may contain virgin PET in addition to recycled PET.
Virgin PET may be a PET in which the diol component is ethylene glycol and the dicarboxylic acid component contains terephthalic acid and isophthalic acid, as described above, or a PET in which the dicarboxylic acid component does not contain isophthalic acid. For example, the dicarboxylic acid component may contain, in addition to aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, an aliphatic dicarboxylic acid, etc.

Specific examples of aliphatic dicarboxylic acids include linear or alicyclic dicarboxylic acids typically having 2 to 40 carbon atoms, such as oxalic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedioic acid, dimer acid, and cyclohexanedicarboxylic acid. Derivatives of aliphatic dicarboxylic acids include lower alkyl esters of the above aliphatic dicarboxylic acids, such as methyl esters, ethyl esters, propyl esters, and butyl esters, and cyclic acid anhydrides of the above aliphatic dicarboxylic acids, such as succinic anhydride. Among these, preferred aliphatic dicarboxylic acids are adipic acid, succinic acid, dimer acid, or mixtures thereof, with those containing succinic acid as the main component being particularly preferred. More preferred derivatives of aliphatic dicarboxylic acids are methyl esters of adipic acid and succinic acid, or mixtures thereof.

The resin in the resin composition constituting the recycled PET-containing resin film may be composed solely of recycled PET, or may contain virgin PET in addition to recycled PET. The recycled PET film may be single-layer or multi-layer. When the recycled PET-containing resin film is a three-layer film consisting of an innermost layer, an intermediate layer, and an outermost layer, it is preferable that the intermediate layer be composed solely of recycled PET or a mixed layer of recycled PET and virgin PET, and that the innermost and outermost layers on both sides be composed solely of virgin PET. Using only virgin PET in the innermost and outermost layers in this way prevents the recycled PET from appearing on the front or back of the resin film, thereby ensuring the hygienic properties of the laminate. When the recycled PET-containing resin film is a two-layer film, it is preferable that one layer be composed solely of recycled PET or a mixed layer of recycled PET and virgin PET, and the other layer be composed solely of virgin PET. When mixing recycled PET and virgin PET to form a single-layer resin film containing recycled PET, methods include feeding the materials separately to the molding machine, or mixing them by dry blending and then feeding them. Of these, mixing by dry blending is preferred from the perspective of ease of operation.

The resin composition that makes up the resin film containing recycled polyethylene PET can contain various additives during or after its production process, as long as the additives do not impair its properties. Examples of additives include plasticizers, UV stabilizers, color inhibitors, matting agents, deodorizers, flame retardants, weather resistance agents, antistatic agents, friction reducers, mold release agents, antioxidants, ion exchange agents, and color pigments. The additives are preferably contained in an amount of 5% to 50% by mass, and preferably 5% to 20% by mass, of the entire resin composition containing PET.

Resin films containing recycled PET can be formed, for example, by filming using the T-die method. Specifically, after drying the above-mentioned PET, it is fed into a melt extruder heated to a temperature above the melting point of PET (Tm) to Tm + 70°C. The resin composition is melted and extruded into a sheet through a die such as a T-die. The extruded sheet is then rapidly cooled and solidified using a rotating cooling drum or the like to form a film. As the melt extruder, a single-screw extruder, twin-screw extruder, vent extruder, tandem extruder, or other type of extruder can be used depending on the purpose.

Resin films containing recycled PET are preferably biaxially stretched. Biaxial stretching can be performed using conventional methods. For example, the film extruded onto a cooling drum as described above is subsequently heated using roll heating, infrared heating, or other methods and stretched in the machine direction to form a machine-stretched film. This stretching is preferably performed using the difference in peripheral speed between two or more rolls. Machine-stretching is typically performed at a temperature between 50°C and 100°C. The machine-stretching ratio is preferably between 2.5x and 4.2x, depending on the required properties of the film's application. If the stretching ratio is less than 2.5x, the thickness of the PET film will become uneven, making it difficult to obtain a good film. The machine-stretched film is then sequentially subjected to the processes of transverse stretching, heat setting, and heat relaxation to form a biaxially stretched film. Transverse stretching is typically performed at a temperature between 50°C and 100°C. The transverse stretching ratio is preferably between 2.5x and 5.0x, depending on the required properties of the application. If the stretching ratio is less than 2.5 times, the film thickness will be uneven, making it difficult to obtain a good film, while if it exceeds 5.0 times, breakage will be more likely to occur during film formation. After transverse stretching, heat setting is performed, and the preferred temperature range for heat setting is PET Tg + 70 to Tm - 10°C. The heat setting time is preferably 1 second or more and 60 seconds or less. For applications requiring reduced heat shrinkage, heat relaxation treatment may be performed as needed.

The thickness of the resin film containing recycled PET varies depending on the application, but is typically about 5 to 500 μm. The resin film containing recycled PET has a breaking strength of 5 kgf/mm2 to 40 kgf/ ^mm2 in the MD direction and ⁵ kgf/ ^mm2 to 35 kgf/ ^mm2 in the TD direction, and a breaking elongation of 50% to 350% in the MD direction and 50% to 300% in the TD direction. Furthermore, the shrinkage rate when left in a 150°C temperature environment for 30 minutes is 0.1% to 5%.

Virgin PET may be fossil fuel polyethylene terephthalate (hereinafter also referred to as fossil fuel PET) or biomass PET. Here, "fossil fuel PET" refers to PET that contains a fossil fuel-derived diol as the diol component and a fossil fuel-derived dicarboxylic acid as the dicarboxylic acid component. Furthermore, recycled PET may be obtained by recycling PET resin products made using fossil fuel PET, or may be obtained by recycling PET resin products made using biomass PET.

Resin films containing recycled PET can be used effectively for packaging products such as bags, lids, and laminated tubes, as well as various label materials and molded sheet products. When using resin films containing recycled PET for packaging products, the thickness of the stretched film is preferably 5 to 30 μm.

<High-stiffness PET film (tough PET film)>
The high-stiffness PET film contains polyester as a primary component and has a loop stiffness of 0.0017 N/15 mm or greater in at least one direction. For example, the high-stiffness film has a loop stiffness of 0.0017 N or greater in at least one of the machine direction (MD) or the transverse direction (TD). For example, the high-stiffness film may have a loop stiffness of 0.0017 N or greater in both the machine direction (MD) and the transverse direction (TD).

Loop stiffness is a parameter that represents the stiffness of a film. Below, we will explain how to measure loop stiffness with reference to Figures 17 to 22. The measurement method described below can be used not only for single-layer films such as stretched plastic film, but also for films containing multiple layers, such as vapor-deposited films and laminated films. A vapor-deposited film is a film that contains a single-layer film, such as stretched plastic film, and a vapor-deposited film formed on the single-layer film. A laminated film is a film that contains multiple laminated films.

Figure 17 is a plan view showing the test specimen 40 and loop stiffness measuring instrument 45, and Figure 18 is a cross-sectional view of the test specimen 40 and loop stiffness measuring instrument 45 taken along line IV-IV in Figure 17. The test specimen 40 is a rectangular film having long and short sides. In this application, the length L1 of the long side of the test specimen 40 is 150 mm, and the length L2 of the short side is 15 mm. As the loop stiffness measuring instrument 45, for example, the No. 581 Loop Stiffness Tester (registered trademark) LOOP STIFFNESS TESTER DA type manufactured by Toyo Seiki Seisakusho, Ltd. can be used. Note that the length L1 of the long side of the test specimen 40 is adjustable as long as the test specimen 40 can be gripped by the pair of chuck portions 46 described below.

The loop stiffness measuring device 45 has a pair of chuck portions 46 for gripping a pair of longitudinal ends of the test specimen 40, and a support member 47 for supporting the chuck portions 46. The chuck portions 46 include a first chuck 461 and a second chuck 462. In the state shown in Figures 17 and 18, the test specimen 40 is placed on the pair of first chucks 461, and the second chuck 462 has not yet gripped the test specimen 40 between itself and the first chuck 461. As described below, during measurement, the test specimen 40 is gripped between the first chuck 461 and the second chuck 462 of the chuck portions 46. The second chuck 462 may be connected to the first chuck 461 via a hinge mechanism.

If the film to be measured, such as a stretched plastic film, vapor-deposited film, or laminated film, is available in a state before it is processed into a packaging product, the test piece 40 may be produced by cutting the film to be measured. The test piece 40 may also be produced by cutting a packaging product made from a packaging material, such as a packaging bag, and removing the film to be measured.

A method for measuring the loop stiffness of a test specimen 40 using a loop stiffness measuring device 45 will now be described. First, as shown in Figures 17 and 18, the test specimen 40 is placed on the first chuck 461 of a pair of chucks 46 spaced apart by a distance L3. In this application, the distance L3 is set so that the length of the loop portion 41 (described below, also referred to as the loop length) is 60 mm. The test specimen 40 includes an inner surface 40x located on the first chuck 461 side and an outer surface 40y located opposite the inner surface 40x. When the test specimen 40 is made of a packaging material, the inner surface 40x and outer surface 40y of the test specimen 40 coincide with the inner and outer surfaces of the packaging material. When the loop portion 41 (described below) is formed on the test specimen 40, the inner surface 40x is located inside the loop portion 41, and the outer surface 40y is located outside the loop portion 41. Next, as shown in FIG. 19, the second chuck 462 is placed on top of the test specimen 40 so that the end of the long side of the test specimen 40 is gripped between the second chuck 462 and the first chuck 461.

20, at least one of the pair of chuck portions 46 is slid on the support member 47 in a direction that reduces the distance between them. This allows a loop portion 41 to be formed on the test specimen 40. The test specimen 40 shown in FIG. 20 has a loop portion 41, a pair of intermediate portions 42, and a pair of fixing portions 43. The pair of fixing portions 43 are portions of the test specimen 40 that are gripped by the pair of chuck portions 46. The pair of intermediate portions 42 are portions of the test specimen 40 that are located between the loop portion 41 and the pair of intermediate portions 42. As shown in FIG. 20, the chuck portion 46 is slid on the support member 47 until the inner surfaces 40x of the pair of intermediate portions 42 come into contact with each other. This allows a loop portion 41 with a loop length of 60 mm to be formed. The loop length of the loop portion 41 is the length of the test piece 40 between position P1 where the surface of one second chuck 462 on the loop portion 41 side intersects with the test piece 40, and position P2 where the surface of the other second chuck 462 on the loop portion 41 side intersects with the test piece 40. If the thickness of the test piece 40 is ignored, the above-mentioned distance L3 is the value obtained by adding 2 x t to the length of the loop portion 41, where t is the thickness of the second chuck 462 of the chuck portion 46.

21, the posture of the chuck portion 46 is adjusted so that the protruding direction Y of the loop portion 41 relative to the chuck portion 46 is horizontal. For example, the posture of the chuck portion 46 supported by the support member 47 is adjusted by moving the support member 47 so that the normal direction of the support member 47 is horizontal. In the example shown in FIG. 21, the protruding direction Y of the loop portion 41 coincides with the thickness direction of the chuck portion. Furthermore, a load cell 48 is prepared at a position a distance Z1 away from the second chuck 462 in the protruding direction Y of the loop portion 41. In this application, the distance Z1 is set to 50 mm. Next, the load cell 48 is moved at a speed V a distance Z2 shown in FIG. 21 toward the loop portion 41 of the test specimen 40. The distance Z2 is set so that the load cell 48 contacts the loop portion 41 and then pushes the loop portion 41 toward the chuck portion 46, as shown in FIGS. 21 and 22. In this application, distance Z2 is set to 40 mm. In this case, distance Z3 between the load cell 48 and the second chuck 462 of the chuck portion 46 when the load cell 48 is pressing the loop portion 41 toward the chuck portion 46 is 10 mm. The speed V at which the load cell 48 is moved is set to 3.3 mm/sec.

Next, as shown in Figure 22, the load cell 48 is moved a distance Z2 toward the chuck portion 46, and with the load cell 48 pressing into the loop portion 41 of the test specimen 40, the load value applied to the load cell 48 from the loop portion 41 is recorded after it stabilizes. The load value obtained in this manner is used as the loop stiffness of the film that constitutes the test specimen 40. Unless otherwise specified, in this application, the environment during loop stiffness measurement is a temperature of 23°C and a relative humidity of 50%.

By using a high-stiffness film with a loop stiffness of 0.0017 N or more in at least one direction as the stretched plastic film, the puncture strength of the stretched plastic film can be increased. As a result, in a laminated film including a high-stiffness film, the puncture strength of the laminated film can be increased to, for example, 13 N or more, more preferably 14 N or more, and even more preferably 15 N or more or 16 N or more.

An example of a high-stiffness film is a high-stiffness PET film containing 51% or more by mass of PET. The PET content in the high-stiffness PET film may be 80% or more by mass, 90% or more by mass, or even 95% or more by mass. The thickness of the high-stiffness film is preferably 5 μm or more, and more preferably 7 μm or more. The thickness of the high-stiffness film may be 10 μm or more, or may be 14 μm or more. The thickness of the high-stiffness film is preferably 30 μm or less, and may be 25 μm or less, or may be 20 μm or less.

Preferred mechanical properties of the high-stiffness film are further described below. The puncture strength of the high-stiffness film is preferably 10 N or more, more preferably 11 N or more. The tensile strength of the high-stiffness film in at least one direction is preferably 250 MPa or more, more preferably 280 MPa or more. For example, the tensile strength of the high-stiffness film in the machine direction is preferably 250 MPa or more, more preferably 280 MPa or more. The tensile strength of the high-stiffness film in the perpendicular direction is preferably 250 MPa or more, more preferably 280 MPa or more. The tensile elongation of the high-stiffness film in at least one direction is preferably 130% or less, more preferably 120% or less. For example, the tensile elongation of the high-stiffness film in the machine direction is preferably 130% or less, more preferably 120% or less. The tensile elongation of the high-stiffness film in the perpendicular direction is preferably 120% or less, more preferably 110% or less. Preferably, the tensile strength of the high stiffness film divided by the tensile elongation in at least one direction is 2.0 MPa/% or greater. For example, the tensile strength of the high stiffness film divided by the tensile elongation in the transverse direction (TD) is preferably 2.0 MPa/% or greater, more preferably 2.2 MPa/% or greater. The tensile strength of the high stiffness film divided by the tensile elongation in the machine direction (MD) is preferably 1.8 MPa/% or greater, more preferably 2.0 MPa/% or greater.

The heat shrinkage of a high stiffness film in at least one direction is preferably 0.7% or less, more preferably 0.5% or less. For example, the heat shrinkage of a high stiffness film in the machine direction is preferably 0.7% or less, more preferably 0.5% or less. The heat shrinkage of a high stiffness film in the perpendicular direction is preferably 0.7% or less, more preferably 0.5% or less. The heating temperature for measuring the heat shrinkage is 100°C, and the heating time is 40 minutes.

The Young's modulus of the high stiffness film in at least one direction is preferably 4.0 GPa or greater, more preferably 4.5 GPa or greater. For example, the Young's modulus of the high stiffness film in the machine direction is preferably 4.0 GPa or greater, more preferably 4.5 GPa or greater. The Young's modulus of the high stiffness film in the perpendicular direction is preferably 4.0 GPa or greater, more preferably 4.5 GPa or greater.

Like tensile strength and tensile elongation, Young's modulus can be measured in accordance with JIS K7127. The measuring instrument used is the STA-1150 tensile tester manufactured by Orientec Co., Ltd. A rectangular film cut from a high-stiffness film with a width of 15 mm and a length of 150 mm can be used as the test specimen. The distance between the pair of chucks holding the test specimen at the start of measurement is 100 mm, and the tensile speed is 300 mm/min. The length of the test specimen can be adjusted as long as it can be held by the pair of chucks. Unless otherwise specified in this application, the environment during measurement of Young's modulus is a temperature of 25°C and a relative humidity of 50%.

Even when a vapor-deposited film is provided, a high-stiffness film has mechanical properties equivalent to those of a single high-stiffness film. For example, a high-stiffness film provided with an aluminum oxide vapor-deposited film 3 has a loop stiffness of 0.0017 N or more in at least one direction. Furthermore, even when an organic coating layer is further provided on the vapor-deposited film, the high-stiffness film has mechanical properties equivalent to those of a single high-stiffness film. For example, a high-stiffness film provided with an aluminum oxide vapor-deposited film and an organic coating layer has a loop stiffness of 0.0017 N or more in at least one direction.

In the manufacturing process for high-stiffness films, for example, a plastic film obtained by melting and molding polyester is first stretched 3 to 4.5 times in both the machine direction and the perpendicular direction at 90 to 145°C in a first stretching step. This is followed by a second stretching step in which the plastic film is stretched 1.1 to 3.0 times in both the machine direction and the perpendicular direction at 100 to 145°C. This is then heat-set at a temperature of 190 to 220°C. This is followed by a relaxation treatment (treatment to reduce the film width) of approximately 0.2 to 2.5% in both the machine direction and the perpendicular direction at a temperature of 100 to 190°C. By adjusting the stretch ratio, stretching temperature, heat-setting temperature, and relaxation rate in these steps, a high-stiffness film with the mechanical properties described above can be obtained.

A specific example of a high-stiffness film is XP-55 manufactured by Toray Industries, Inc. This high-stiffness film is biaxially stretched, contains at least 90% by mass of PET, and is 16 μm thick. The measured loop stiffness of this high-stiffness PET film was 0.0021 N in both the machine direction and the perpendicular direction. The Young's modulus of the high-stiffness PET film in the machine direction was 4.8 GPa, and the Young's modulus of the high-stiffness PET film in the perpendicular direction was 4.7 GPa. The tensile strength of the high-stiffness PET film in the machine direction was 292 MPa, and the tensile strength of the high-stiffness PET film in the perpendicular direction was 257 MPa. The tensile elongation of the high-stiffness PET film in the machine direction was 107%, and the tensile elongation of the high-stiffness PET film in the perpendicular direction was 102%. In this case, the tensile strength of the high-stiffness PET film in the machine direction divided by the tensile elongation was 2.73 MPa/%. The tensile strength of the high-stiffness PET film in the perpendicular direction divided by the tensile elongation was 2.52 MPa/%. The heat shrinkage of the high-stiffness PET film in both the machine direction and perpendicular direction was 0.4%.

The substrate 1 may be a single layer or a multi-layer structure of two or more layers. In the case of a multi-layer structure, the layers may be of the same composition or of different compositions. In the case of a multi-layer structure, the layers may be bonded together via an adhesive layer or the like.

[Aluminum oxide vapor deposition film]
Next, the vapor-deposited film 2 will be described. The vapor-deposited film 2 contains aluminum oxide. The aluminum is present in the vapor-deposited film 2 in a state in which, for example, an elemental bond _Al2O3 is formed. The vapor-deposited film 2 may further _contain a metal oxide such as silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, magnesium oxide, titanium oxide, tin oxide, indium oxide, zinc oxide, or zirconium oxide, or a nitride or carbide of these metals. The thickness of the vapor-deposited film 2 is preferably 3 nm or more and 100 nm or less, and more preferably 5 nm or more and 50 nm or less. Note that the "aluminum oxide vapor-deposited film" in the present invention means a "vapor-deposited film containing aluminum oxide" as described above, _and may contain aluminum hydroxide _Al2O4H or the like in addition to _aluminum oxide _Al2O3 .

(TOF-SIMS analysis)
The composition of the barrier film according to this embodiment will be described in detail with reference to FIG. 9 of Example 2, which will be described later. FIG. 9 is an example of a graphical analysis diagram showing the intensities of elements and element bonds contained in the barrier film, measured by etching the barrier film A shown in FIG. 1 from the surface side of the vapor-deposited film 2 using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The unit of the vertical axis of the graph (intensity) is expressed as a common logarithm of the ion intensity. The unit of the horizontal axis of the graph (Et times) is the etching time.

TOF-SIMS (Time-of-Flight secondary ion mass spectrometry)
Secondary Ion Mass Spectrometry (SMS) is a method of mass analysis in which a primary ion beam from a primary ion gun is irradiated onto the surface of a solid sample to be analyzed, and secondary ions sputtered and emitted from the sample surface are mass-separated using their time-of-flight differences (time-of-flight is proportional to the square root of mass).

Here, by detecting the secondary ion intensity while sputtering is progressing, the concentration distribution of the detected element in the depth direction on the sample surface can be determined by converting the transition time into depth data for the ion intensity of the secondary ions, i.e., the ions of the detected element or molecular ions bonded to the detected element.

The depth of the depressions formed on the sample surface by primary ion irradiation is measured in advance using a surface roughness meter, and the average sputtering rate is calculated from the depression depth and transition time. Under the assumption that the sputtering rate is constant, the depth (sputtering amount) can be calculated from the irradiation time (i.e., transition time) or number of irradiation cycles.

Specifically, while repeatedly soft-etching the outermost surface of the vapor-deposited film 2 at a constant rate using a Cs (cesium) ion gun, a time-of-flight secondary ion mass spectrometer is used to measure the elements and element bonds at the interface between the vapor-deposited film 2 and the substrate 1, as well as the elements and element bonds of the vapor-deposited film 2, thereby obtaining graphs of the measured elements and element bonds. As a specific example, as shown in Fig. 9, at least the element bond _AL2O3 , the element bond _{AL2O4H ,} and the element bond C6 are detected from the _barrier film according to this embodiment. The example shown in Fig. 9 shows an example in which the strengths of these three types of element bonds were measured.

In Figure 9, the position of Et time _T1 where the intensity of the graph for element C6 is half of the maximum intensity is taken as the interface between the plastic substrate and aluminum oxide, and the area from the barrier film surface ( _T0 ) to the interface _T1 is treated as an aluminum oxide vapor-deposited film (X in Figure 9), and the position 1/3 of the Et time from _T0 to _T1 , i.e., 1/3X, is taken as _T2 .

At this time, the ratio ( _I22 / _I21 ) of _the intensity _I22 of the elemental bond _Al2O4H to the intensity _I21 of the elemental bond _Al2O3 at _T2 is _0.30 or less, preferably 0.20 or less, and more preferably 0.10 or less. This allows the ratio of elemental bond _Al2O4H to be small in the surface vicinity region of the vapor- _deposited film, and a region mainly consisting _{of Al2O3} exists, thereby improving the barrier performance.

9, the aluminum oxide vapor-deposited film has a maximum peak Tp of the intensity _of the elemental bond _Al2O4H . When multiple maximum peaks are recognized, the first peak from the surface side of the vapor-deposited film is the maximum peak. The region from Tp to the interface _T1 is referred to as the transition region. In the present invention, the depth position of the maximum peak (Tp) with respect to X, which corresponds to the thickness of the vapor-deposited film, is preferably 55% to 95% from the surface side (opposite the substrate side) of the vapor-deposited film. Furthermore, the ratio (I _P2 /I _P1 ) of the intensity _{I P2 of the} elemental bond _Al2O4H to the intensity I _P1 of the elemental bond _Al2O3 at position Tp is preferably 0.10 to 4.00.

When the maximum peak derived from the element bond Al ₂ O ₄ H is present at 55% or more and 95% or less, that is, closer to the substrate side, a region mainly composed of Al ₂ O ₄ H exists on the substrate side of the deposited film, while a region mainly composed of Al ₂ O ₃ exists in the surface vicinity region of the deposited film as described above. In other words, the structure is Al ₂ O ₃ main region/Al ₂ O ₄ H main region/substrate, and this structure enables high barrier properties.

_The ratio ( _I22 / _I21 ) of the intensity _I22 of the elemental bond _Al2O4H to the intensity _{I21 of} the elemental bond _Al2O3 at _T2 , the depth position of the maximum peak (Tp), and the ratio ( _Ip2 / _Ip1 ) of the intensity _Ip2 of the elemental bond _Al2O4H to the intensity _Ip1 of _the elemental bond _Al2O3 at position _Tp can be adjusted by controlling the combination of the pretreatment, particularly the oxygen plasma treatment conditions, the plasma-assisted treatment conditions during deposition, and the oxygen concentration during deposition in forming the aluminum oxide vapor deposition film.

(FT-IR evaluation)
The barrier film of the present invention has an absorption peak at 940 ^cm to 960 ^cm , preferably 950 ^cm to 960 ^cm , in the infrared absorption spectrum from the surface side of the vapor-deposited film. This peak at 940 ^cm to 960 ^cm is derived from an Al—O bond, and the presence of this peak improves the film density of aluminum oxide.

Furthermore, the ratio of the absorption intensity of the absorption peak at 3,350 cm ⁻¹ or more and 3,550 cm ⁻¹ or less, which is attributable to O-H bonds, to the absorption intensity of the absorption peak at 940 cm ⁻¹ or more and 960 cm ⁻¹ or less, which is attributable to Al—O bonds, is 0.20 or less, preferably 0.10 or less. Within this range, the composition becomes close to a complete oxide film of aluminum oxide, and the barrier properties are improved.

The FT-IR measurement conditions were as described in the examples.

(Film forming equipment)
Next, an example of a film formation apparatus 10 used in the method for manufacturing a barrier film will be described. As shown in Fig. 2, the film formation 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 formation mechanism 11C for forming a vapor-deposited film 2. In the example shown in Fig. 5, the film formation apparatus 10 further includes a decompression chamber 12. The decompression chamber 12 has a decompression mechanism, such as a vacuum pump described below, that adjusts the atmosphere in at least a part of the internal space of the decompression chamber 12 to atmospheric pressure or below.

In the example shown in FIG. 2, the decompression chamber 12 includes a substrate transfer chamber 12A in which the substrate transfer 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 transfer chamber 12A and the plasma pretreatment chamber 12B, between the plasma pretreatment chamber 12B and the film deposition chamber 12C, and between the substrate transfer chamber 12A and the film deposition chamber 12C, and may have partitions 35a to 35c separating each chamber.

The substrate transfer chamber 12A, plasma pretreatment chamber 12B, and film deposition chamber 12C will now be described. The plasma pretreatment chamber 12B and film deposition chamber 12C are each located adjacent to the substrate transfer chamber 12A, and each has a portion that connects to the substrate transfer chamber 12A. This allows the substrate 1 to be transferred between the substrate transfer chamber 12A and the plasma pretreatment chamber 12B, and between the substrate transfer chamber 12A and the film deposition chamber 12C without being exposed to the atmosphere. For example, between the substrate transfer chamber 12A and the plasma pretreatment chamber 12B, the substrate 1 can be transferred through an opening in the partition wall 35a. A similar structure is also used between the substrate transfer chamber 12A and the film deposition chamber 12C, allowing the substrate 1 to be transferred between the substrate transfer chamber 12A and the film deposition chamber 12C.

The function of the decompression mechanism of the decompression chamber 12 will now be described. The decompression mechanism of the decompression chamber 12 is configured to reduce the pressure 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 also be configured to reduce the pressure in each of the substrate transfer chamber 12A, plasma pretreatment chamber 12B, and film formation chamber 12C, which are separated by partitions 35a to 35c, to below atmospheric pressure.

The configuration of the decompression mechanism of the decompression chamber 12 will now 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 inside the plasma pretreatment chamber 12B can be appropriately controlled when performing the plasma pretreatment described below. In addition, the method described below can prevent the plasma supplied into the plasma pretreatment chamber 12B from diffusing to other chambers. 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. The vacuum pump may be a dry pump, turbomolecular pump, cryopump, rotary pump, diffusion pump, or the like.

The substrate transport mechanism 11A for the substrate 1 of the film formation apparatus 10 according to this embodiment will be described below, along with the transport path of the substrate 1. The substrate transport mechanism 11A is a mechanism for transporting the substrate 1, located in the substrate transport chamber 12A. In the example shown in FIG. 2, the substrate transport mechanism 11A includes an unwinding roller 13 to which a roll of substrate 1 is attached, a take-up roller 15 that winds up the substrate 1, and guide rolls 14a-14d. The substrate 1 sent out from the substrate transport mechanism 11A is then transported by a pre-treatment roller 20 (described below) located in the plasma pre-treatment chamber 12B, and a film formation roller 25 (described below) located in the film formation chamber 12C.

Although not shown, the substrate conveying mechanism 11A may further include a tension pickup roller. By including a tension pickup roller in the substrate conveying mechanism 11A, the substrate 1 can be conveyed while adjusting the tension applied to the substrate 1.

(Plasma pretreatment mechanism)
The plasma pretreatment mechanism 11B will now 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. Plasma pretreatment activates the surface of the substrate 1, making it easier for nitrogen contained inside the substrate 1 to collect on the surface of the substrate 1, or making it easier for nitrogen contained in the environment surrounding the substrate 1 to be incorporated into the surface of the substrate 1. Therefore, when a vapor-deposited film 2 is formed on the surface of the substrate 1 that has been subjected to plasma pretreatment, a peak of elemental bond CN can be formed at the interface between the substrate 1 and the vapor-deposited film 2. The plasma pretreatment mechanism 11B shown in FIG. 2 includes a pretreatment roller 20 arranged in the plasma pretreatment chamber 12B, an electrode unit 21 facing the pretreatment roller 20, and a magnetic field generating unit 23 that generates a magnetic field between the pretreatment roller 20 and the electrode unit 21.

The pretreatment roller 20 will now be described. Figure 3 is an enlarged view of the area enclosed by the dashed line marked with the symbol VI in Figure 2. Note that Figure 3 omits the power supply wiring 31 connecting the power source 32 shown in Figure 2 to the electrode unit 21 (described later), as well as the plasma P generated by the plasma pretreatment mechanism 11B. The pretreatment roller 20 has a rotation axis X. The pretreatment roller 20 is positioned so that at least the rotation axis X is located within the plasma pretreatment chamber 12B, which is partitioned by partition walls 35a and 35b. A substrate 1 having a dimension in the direction of the rotation axis X is wrapped around the pretreatment roller 20. 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 portion thereof is exposed on the substrate transport chamber 12A side. In the example shown in FIG. 2, the plasma pretreatment chamber 12B and the substrate transport chamber 12A are connected via an opening provided in the partition wall 35a, and a portion of the pretreatment roller 20 is exposed on the substrate transport chamber 12A side through this opening. A gap is provided between the partition wall 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 this 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 surface temperature 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 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.

By having a temperature adjustment mechanism in the pretreatment roller 20, shrinkage or damage to the substrate 1 due to heat can be prevented 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. Furthermore, using the above materials for the pretreatment roller 20 increases the thermal conductivity of the pretreatment roller 20 itself, making it easier to control the temperature of the pretreatment roller 20.

The electrode unit 21 will now be described. In the example shown in Figures 2 and 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 Figures 2 and 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 itself and the pretreatment roller 20 by applying an AC voltage between itself and the pretreatment roller 20. The electrode unit 21 preferably forms an electric field between itself and the pretreatment roller 20 so that the generated plasma moves perpendicular to the surface of the substrate 1 toward the surface of the substrate 1. This allows the substrate 1 to be pretreated efficiently. Therefore, when a vapor deposition film 2 is formed on the surface of the plasma-pretreated substrate 1, the peak intensity H1 of the peak of the elemental bond CN formed at the interface between the substrate 1 and the vapor deposition film 2 can be increased.

The number of electrode units 21 is preferably two or more. The two or more electrode units 21 are preferably aligned along the transport direction of the substrate 1. In the example shown in Figures 2 and 3, the film forming apparatus 10 has two electrode units 21. The number of electrode units 21 is, for example, 12 or less.

The effect of two or more electrode units 21 lined up along the transport direction of the substrate 1 will now be explained. 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, if the electrode unit 21 is a flat, plate-shaped member, the larger the dimension of the electrode unit 21 in the transport direction, the greater the distance from the end of the first surface 21c of the electrode unit 21, which is the surface facing the pretreatment roller 20, to the pretreatment roller 20 in the transport direction, resulting in a decrease in plasma processing ability.

In the film forming apparatus 10, two or more electrode units 21 are aligned 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. Furthermore, by reducing the dimensions of the electrode units 21, the distance from the end of the first surface 21c of the electrode units 21 to the pretreatment roller 20 in the transport direction can be reduced, allowing plasma to be generated uniformly in the transport direction.

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

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 generating unit 23 can effectively generate a magnetic field between the pre-treatment roller 20 and the electrode unit 21. Furthermore, 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 generating plasma 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, each of the two or more magnetic field forming units 23 is preferably 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 to the second surface 21d of the electrode portion 21 will be described. As shown in Figures 2 and 3, the first magnet 231 and the second magnet 232 each have a north pole and a south pole. The symbol N in Figures 2 and 3 indicates the north pole of the first magnet 231 or the second magnet 232. The symbol S in Figures 2 and 3 indicates the south pole of the first magnet 231 or the second magnet 232. One of the north pole or south pole of the first magnet 231 is located closer to the substrate 1 than the other. The other of the north pole or south pole of the second magnet 232 is located closer to the substrate 1 than the other. In the example shown in Figures 2 and 3, the north pole of the first magnet 231 is located closer to the substrate 1 than the south pole of the first magnet 231, and the south pole of the second magnet 232 is located closer to the substrate 1 than the north 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, we will explain 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. Figure 4 is a plan view of the electrode unit 21 and 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 taken along line VIII-VIII in Figure 4. Furthermore, in Figure 4, direction D1 is the direction in which the rotation axis X of the pre-treatment roller 20 extends.

As shown in Figures 4 and 5, the first magnet 231 has a first axial portion 231c. As shown in Figure 4, the first axial portion 231c extends along direction D1, i.e., along the rotation axis X of the pre-treatment 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 Figure 4, the first magnet 231 provided on one electrode unit 21 has one first axial portion 231c.

Furthermore, as shown in Figures 4 and 5, the second magnet 232 has a second axial portion 232c. As shown in Figure 4, the second axial portion 232c, like the first axial portion 231c, also extends along direction D1, i.e., along the rotation axis X.

By including portions of both the first magnet 231 and the second magnet 232 that extend 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 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.

As shown in Figure 5, 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 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 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 pre-treatment roller 20 and the electrode unit 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 as well as two connecting portions 232d arranged 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). Electromagnets can also be used as the magnetic field generating unit 23.

The magnetic flux density of the magnets of the magnetic field generating 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, generating a sufficiently high-density plasma and allowing a good pretreatment surface to be formed at high speed. On the other hand, increasing the magnetic flux density on the surface of the substrate 1 to more than 10,000 gauss requires an expensive magnet or magnetic field generating mechanism.

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 plasma raw material gas 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 may be provided on the wall surface of the plasma pretreatment chamber 12B and include a hole for ejecting the plasma raw material gas. The plasma raw material gas supply unit may also have a nozzle for ejecting 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 mixture of these gases. As the plasma raw material gas, a single inert gas, a single active gas, or a mixture of two or more gases contained in the inert gas or active gas may be used. As the plasma raw material gas, a mixture 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 includes a substrate transport chamber 12A and a film formation chamber 1
The plasma pre-treatment chamber 12B is disposed in a plasma pre-treatment chamber 12B separated from the substrate transport chamber 12A and the film deposition chamber 12C by a partition wall. By separating the plasma pre-treatment chamber 12B from other regions such as the substrate transport chamber 12A and the film deposition chamber 12C, it becomes easier to independently adjust the atmosphere in the plasma pre-treatment chamber 12B. This allows, for example,
This makes it easier to control the plasma raw material gas concentration in the space where pretreatment roller 20 and electrode unit 21 face each other, improving the productivity of the laminated film.

In this embodiment, the voltage applied between the pretreatment roller 20 and the electrode unit 21 of the plasma pretreatment mechanism 11B is an AC voltage. By applying the AC voltage, plasma is generated between the pretreatment roller 20 and the electrode unit 21. Preferably, by applying the AC voltage, an electric field is formed so that the generated plasma moves toward the surface of the substrate 1 in a direction perpendicular to the surface of the substrate 1.

The value of the AC voltage applied between the pretreatment roller 20 and the electrode unit 21 is preferably 250 V or more and 1000 V or less. When the AC voltage has the above value, plasma with sufficient plasma density can be generated between the pretreatment roller 20 and the electrode unit 21. Here, the value of the AC voltage refers to the effective value Ve. The effective value Ve of the AC voltage can be calculated using the following formula (2), where Vm is the maximum value of the AC voltage.

The AC voltage applied between the pretreatment roller 20 and the electrode unit 21 has a frequency of, for example, 20 kHz or more and 500 kHz or less.

(Film forming 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 disposed in the film formation chamber 12C, and an evaporation mechanism 24.

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

The material of the film-forming roller 25 will now be described. The film-forming roller 25 is preferably made of 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. Furthermore, using the above materials for the film-forming roller 25 increases the thermal conductivity of the film-forming roller 25 itself, resulting in excellent temperature controllability. The average surface roughness Ra of the surface 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 also have a temperature adjustment mechanism that adjusts the surface temperature of the film-forming roller 25. The temperature adjustment mechanism, for example, has a circulation path inside the film-forming roller 25 for circulating a cooling medium or heat source medium. 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 also have a heater installed opposite the film-forming roller 25. When the film-forming mechanism 11C forms a film by vapor deposition, in consideration of the heat resistance constraints of related mechanical components and versatility, the temperature adjustment mechanism preferably adjusts the surface temperature of the film-forming roller 25 to a target temperature within the range of -20°C to 200°C. By having the film-forming roller 25 have a temperature adjustment mechanism, fluctuations in the temperature of the substrate 1 caused by heat generated during film formation can be suppressed.

The evaporation mechanism 24 will now be described. Figure 6 is an enlarged view of the area enclosed by the dashed line and marked with the symbol IX in Figure 2. It shows a specific configuration of the evaporation mechanism 24, which was omitted in Figure 5, and also shows the evaporation material supply unit 61, which supplies the evaporation material, which was omitted in Figure 2. Note that the decompression chamber 12 and partition walls 35b and 35c are omitted from Figure 6. The evaporation mechanism 24 evaporates the evaporation material containing aluminum. The evaporated evaporation material adheres to the substrate 1, forming an aluminum-containing evaporation film on the surface of the substrate 1. In this embodiment, the evaporation mechanism 24 employs a resistance heating system. In the example shown in Figure 6, the evaporation mechanism 24 includes a boat 24b. In this embodiment, the boat 24b includes a power supply (not shown) and a resistor (not shown) electrically connected to the power supply. Multiple 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 vapor deposition material supply unit 61 that supplies vapor deposition material to the evaporation mechanism 24. FIG. 6 shows an example in which the vapor deposition material supply unit 61 continuously feeds aluminum metal wire.

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

The film formation 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 Figures 2 and 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 within the hollow portion. In the example shown in Figure 6, the hollow cathode 51 is arranged so that the opening of the hollow portion of the hollow cathode 51 is positioned diagonally above the boat 24b. Although not shown, the plasma supply mechanism 50 of this embodiment also has an anode facing the opening, which draws plasma from the opening of the hollow cathode 51. The plasma supply mechanism 50 of this embodiment generates plasma within the hollow portion of the hollow cathode 51 and draws the plasma between the surface of the substrate 1 and the evaporation mechanism 24 using the opposing anode, thereby generating a strong plasma between the surface of the substrate 1 and the evaporation mechanism 24. The position of the opposing anodes is not particularly limited, as long as the opposing anodes can extract 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 disposed on both sides of the boat 24b in the width direction of the substrate 1. In this case, the film formation mechanism 11C may have multiple boats 24b and multiple opposing anodes, which 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 a plasma raw material gas at least into the hollow cathode 51. The plasma raw material gas supplied by the raw material supply device may be, for example, the same 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.

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 achieved, activating the aluminum and oxygen gas evaporated in the evaporation mechanism 24 and promoting the reaction or bonding between the aluminum and oxygen gas. This increases the proportion of aluminum present as aluminum oxide in the evaporated film 2 formed on the surface of the substrate 1, stabilizing the properties of the evaporated film 2.

Although not shown, the film forming apparatus 10 may also include a substrate charge removal unit in the substrate transport chamber 12A, located downstream of the film formation chamber 12C in the transport direction of the substrate 1. The substrate charge removal unit 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 unit may be configured to remove charge from one side of the substrate 1, or may be configured to remove charge from both sides of the substrate 1.

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

When post-treatment is performed by generating a discharge using a plasma treatment device or glow discharge device, a discharge gas such as argon, oxygen, nitrogen, or helium, or a mixture of these gases, is 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.

By installing the substrate charge removal unit in the substrate transport chamber 12A, downstream of the film-forming chamber 12C in the transport direction of the substrate 1, and removing the charge from the substrate 1, the substrate 1 can be quickly separated from the film-forming roller 25 at a predetermined position for transport. 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 supply 32 electrically connected to the pretreatment roller 20 and the electrode unit 21. In the example shown in FIG. 5 , the power supply 32 is electrically connected to the pretreatment roller 20 and the electrode unit 21 via power supply wiring 31. The power supply 32 is, for example, an AC power supply. When the power supply 32 is an AC power supply, the power supply 32 can apply an AC voltage having a frequency of, for example, 20 kHz to 500 kHz between the pretreatment roller 20 and the electrode unit 21. The input power that can be applied by the power supply 32 (the power that can be applied per meter of 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 to 20 kW/m. The pretreatment roller 20 may be installed at an electrically earth level or at an electrically floating level.

(Method for manufacturing a barrier film)
Next, a method for producing the barrier film shown in Fig. 1 using the above-mentioned film formation apparatus 10 will be described. First, a film formation method for forming a vapor-deposited film 2 on the surface of a substrate 1 will be described. In film formation using the film formation apparatus 10, a plasma pretreatment step in which plasma pretreatment is performed on the surface of the substrate 1 using the plasma pretreatment mechanism 11B, and a film formation step in which a vapor-deposited film is formed on the surface of the substrate 1 using the 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 AC voltage described above is applied between the pretreatment roller 20 and the electrode unit 21. When applying the AC voltage, input power control or impedance control may be performed.

The plasma raw material gas supplied in the pretreatment process is oxygen alone or a mixture of oxygen and an inert gas, which is supplied from a gas reservoir via a flow controller while the gas flow rate is measured. Examples of inert gases include one or more mixed gases selected from the group consisting of argon, helium, and nitrogen.

For plasma treatment, the mixing 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 between 6/1 and 1/1, the energy required to form the vapor-deposited aluminum film on the resin substrate increases, and by setting it between 5/2 and 3/2, the degree of oxidation of the vapor-deposited aluminum oxide film can be increased, ensuring adhesion between the vapor-deposited 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 . At 50 W·sec/m2 or ^less , the effect of plasma pretreatment is not observed, and at 8000 W·sec/m2 or ^more , the resin substrate tends to be deteriorated by the plasma, such as worn, damaged, discolored, and burned. In particular, to form an aluminum oxide layer, the plasma intensity in the plasma pretreatment is preferably 100 W·sec/ ^m2 or more and 1000 W·sec/ ^m2 or less.

When an AC voltage is applied between the pretreatment roller 20 and the electrode unit 21, the pressure inside the plasma pretreatment chamber 12B is reduced to below atmospheric pressure by the decompression chamber 12. In this case, the pressure inside the plasma pretreatment chamber 12B is adjusted, for example, so that glow discharge can be generated between the pretreatment roller 20 and the electrode unit 21 by applying an AC voltage. The degree of vacuum inside 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, with a pressure of 1 Pa or more and 20 Pa or less being particularly preferred.

The function of the magnetic field generating unit 23 in the plasma pretreatment process will now be explained. The magnetic field generating unit 23 generates 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. This increases the frequency of collisions between electrons and plasma raw material gas in the region where the magnetic field is formed, thereby increasing and localizing the plasma density and improving the efficiency of 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 where an aluminum oxide vapor deposition film is formed using the film formation mechanism 11C having the evaporation mechanism 24 shown in FIG.

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

The aluminum is evaporated within the boat 24b by heating. For convenience, Figure 6 shows evaporated aluminum vapor 63. The oxygen gas that oxidizes the aluminum can be supplied either as pure oxygen or as a mixture with an inert gas such as argon. By controlling the amount of oxygen, both barrier properties and transparency can be achieved. The degree of vacuum at this time is preferably 0.05 Pa or more and 8.00 Pa or less.

Furthermore, we will explain a method of supplying plasma between the surface of the substrate 1 and the evaporation mechanism 24 using the plasma supply mechanism 50, i.e., plasma assistance during deposition. 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 refers to a discharge with a current value of, for example, 10 A or more.

By supplying plasma between the surface of the substrate 1 and the evaporation mechanism 24 while evaporating aluminum, 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 Figure 1 can be produced.

The plasma raw material gas supplied by the plasma supply mechanism 50 is preferably oxygen alone or a mixture of oxygen gas and an inert 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. A magnetic field is generated in the space between the electrode unit 21 and the pretreatment roller 20 using the magnetic field generating unit 23 located on the side of the electrode unit 21 opposite the side 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 therefore improves adhesion between the film formed in the film formation process and the substrate 1.

(Laminate)
An example of a laminate formed using the barrier film according to this embodiment will be described. FIG. 7 is a diagram showing an example of a laminate 40 formed using the barrier film according to this embodiment. The laminate 40 comprises the barrier film shown in FIG. 1 and a sealant layer 7. Specifically, the laminate 40 further comprises, on the vapor-deposited film of the barrier film shown in FIG. 1, an adhesive layer 4, a second substrate 5 made of polyamide or the like, an adhesive layer 6, and a sealant layer 7, in this order. The laminate of the present invention is formed by laminating at least one heat-sealable layer on a barrier film, and a heat-sealable thermoplastic resin is laminated as the innermost layer, with or without an adhesive layer interposed therebetween, to impart sealability such as heat sealing.

Examples of thermoplastic resins that make up the sealant layer 7 include films containing one or more of the following resins: low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, polypropylene, polymethylpentene, polystyrene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-propylene copolymer, and elastomer. The thickness of the sealant layer 7 is preferably 3 to 100 μm, and more preferably 15 to 70 μm.

(packaging material)
The above laminate is useful when used as a packaging material for producing packaging bags for containing contents such as food. In particular, a barrier film that maintains high adhesion even when subjected to heat treatment is suitable for use as a material for packaging bags. When a packaging product is produced using the barrier film as a material, the above barrier film can suppress peeling of the layers that make up the barrier film in the packaging product. For example, when a packaging bag produced using the barrier film as a material is subjected to a heat sterilization treatment using hot water, such as a retort treatment or a boiling treatment, peeling of the layers that make up the barrier film, particularly peeling of the vapor-deposited film 2 from the substrate 1, can be suppressed.

Retort processing is a process in which the contents are filled into a packaging bag, the bag is sealed, and then the packaging bag is heated under pressure using steam or heated hot water. The temperature for retort processing is, for example, 120°C or higher. Boiling processing is a process in which the contents are filled into a packaging bag, the bag is sealed, and then the packaging bag is heated in a water bath under atmospheric pressure. The temperature for boiling processing is, for example, 90°C or higher and 100°C or lower.

The present invention will be described in further detail below using examples, but the present invention is not limited to these descriptions in any way. First, barrier films according to Examples 1 to 3 and Comparative Examples 1 to 3 were produced using the film-forming apparatus and film-forming method described in this embodiment. Pretreatment conditions, deposition conditions, etc. are summarized in Table 1. In Table 1, "Good" in the "Plasma pretreatment" category indicates that plasma pretreatment was performed, and "Poor" indicates that plasma pretreatment was not performed. Furthermore, in the "Plasma assistance during deposition" category, "Good" indicates that plasma assistance was performed during deposition, and "Poor" indicates that plasma assistance was not performed during deposition.

Example 1
A biaxially stretched polyethylene terephthalate film (PET film) having a thickness of 12 μm was used as the substrate 1, and a plasma pretreatment step and a film formation step were carried out using the film formation apparatus 10 shown in FIG.

In the pretreatment step, plasma pretreatment was performed on the surface of the substrate 1 using the plasma pretreatment mechanism 11B shown in Figures 2 and 3. Specifically, first, a mixed gas of oxygen ( _O2 ) and argon (Ar) ( _O2 :Ar = 2.5:1) was supplied to the plasma pretreatment chamber 12B using the plasma raw material gas supply unit, while the pressure inside the plasma pretreatment chamber 12B was adjusted using the decompression chamber 12. Next, a voltage was applied between the pretreatment roller 20 and the electrode unit 21 to generate plasma, and plasma pretreatment was performed on the surface of the substrate 1. The pressure inside the plasma pretreatment chamber 12B was 6.2 Pa, and a 1000 Gauss permanent magnet was used as the magnetic field generating unit 23. The plasma density was 417 W·sec/ ^m2 .

In the film formation process, a vapor deposition film 2 containing aluminum oxide was formed by vacuum deposition using an evaporation mechanism 24 as shown in Fig. 6. Specifically, the degree of vacuum in the film formation chamber 12C was adjusted to 1.5 Pa, and then aluminum metal wires were supplied as a vapor deposition material into a boat 24b. The evaporation material in the boat 24b was heated using the resistance heating evaporation mechanism 24, and the aluminum was evaporated so as to reach the surface of the substrate 1. At the same time, oxygen was supplied at 12,500 sccm, and a vapor deposition film 2 was formed on the surface of the substrate 1.

In addition, the plasma supply mechanism 50 used had a configuration including a hollow cathode 51 as shown in Figure 6 and anodes (not shown) arranged on both sides of the boat 24b in the width direction of the substrate 1 and facing the opening of the hollow cathode 51, and a plasma raw material gas ( _O2 :Ar = 35:1) was supplied to the hollow cathode 51, discharge was caused to excite plasma, and this plasma was extracted by the opposing anodes to between the surface of the substrate 1 and the evaporation mechanism 24, thereby providing plasma assistance during deposition.

Using the above method, a barrier film comprising the substrate 1 and vapor-deposited film 2 shown in Figure 1 was produced at a conveying speed of 600 m/min. The thickness of the vapor-deposited film 2 of the produced barrier film was 8 nm.

Example 2
A barrier film of Example 2 was produced in the same manner as in Example 1, except that the conveying speed was 480 m/min and the thickness of the vapor-deposited film 2 was 13 nm.

Example 3
A barrier film of Example 3 was produced in the same manner as in Example 2, except that the plasma pretreatment in Example 2 was not performed.

Example 4
A barrier film of Example 4, which was not subjected to plasma pretreatment, was produced in the same manner as in Example 3, except that a film-forming apparatus different from those used in Examples 1 to 3 was used and the production conditions were changed to those shown in Table 1.

Example 5
A barrier film of Example 5, which had been subjected to plasma pretreatment, was produced in the same manner as in Example 1, except that a film-forming apparatus different from those used in Examples 1 to 3 was used and the production conditions were changed to those shown in Table 1.

(Comparative Example 1)
As shown in Table 1, the barrier film of Comparative Example 1 was produced in the same manner as in Example 1, except that no plasma pretreatment was performed, an EB (electron beam) type evaporation mechanism (not shown) was used instead of the resistance heating type evaporation mechanism 24, no plasma-assisted treatment was performed during deposition, the oxygen supply amount was set to 8,500 sccm, and the degree of vacuum during deposition was set to 0.15 Pa.

(Comparative Example 2)
As shown in Table 1, the barrier film of Comparative Example 2 was produced in the same manner as in Example 1, except that the degree of vacuum in the plasma pretreatment chamber 12B was set to 3.5 Pa, plasma-assisted treatment was not performed during deposition, the oxygen supply amount was 10,000 sccm, and the degree of vacuum during deposition was 0.02 Pa.

(Comparative Example 3)
As shown in Table 1, a barrier film of Comparative Example 3 was produced in the same manner as in Comparative Example 2, except that the conveying speed was 480 m/min and the thickness of the vapor-deposited film 2 was 13 nm.

[TOF-SIMS analysis]
For the barrier films of Examples 1 to 5 and Comparative Examples 1 and 2, mass analysis of C 6 (mass number 72.00) derived from the resin substrate, Al 2 O 3 (mass number 101.94) derived from the aluminum oxide vapor-deposited film, and Al ₂ O _{4 H} (mass number 118.93) derived from the aluminum oxide vapor-deposited film was performed using a time-of-flight secondary ion mass spectrometer (TOF.SIMS5, manufactured by ION TOF) under the following measurement conditions from the vapor-deposited film surface side of the barrier film while repeatedly soft-etching at a constant rate using a _Cs ( _cesium ) ion gun. Graphical analyses of the measurement results are shown in FIGS. 8 to 14 . FIG. 8 shows the measurement results for Example 1, FIG. 9 shows the measurement results for Example 2, FIG. 10 shows the measurement results for Example 3, FIG. 11 shows the measurement results for Example 4, FIG. 12 shows the measurement results for Example 5, FIG. 13 shows the measurement results for Comparative Example 1, and FIG. 14 shows the measurement results for Comparative Example 2. In the figure, the unit of the vertical axis (intensity) is the common logarithm of the ion intensity, and the unit of the horizontal axis (Et times (s)) is the number of seconds during which etching was performed.

TOF-SIMS measurement conditions: Primary ion type: Bi ³⁺⁺ (0.2 pA, 100 μs)
・Measurement area: 150 x 150 μm ²
Etching gun type: Cs (1 keV, 60 nA)
Etching area: 600 x 600 μm ²
Etching rate: 10 sec/Cycle

The position where the strength of C6, a constituent material of the plastic substrate, is half of its maximum strength (C6 half-life 1/2C6 (shown as C6 half-life (X) in the table)) was defined as the interface between the film substrate and the aluminum oxide vapor-deposited film. The aluminum oxide vapor-deposited film was defined as the area from the vapor-deposited film surface (the position before etching) to this interface, and the position 1/3 of the way from the vapor-deposited film surface in the total vapor-deposited film thickness was determined. The _ratio of the strength of elemental bond _Al2O4H to the strength of elemental bond _Al2O3 ( _Al2O4H / _Al2O3 ) at the position 1/3 _of the way from _the vapor-deposited film _surface was then calculated.

The position showing the intensity peak of the measured elemental bond _Al2O4H (mass number _118.93 ) was determined in terms of etching seconds (peak position Y), and the depth position from the surface of the deposited film at that position (peak position Y/X, unit: %) and the ratio of the elemental bond _Al2O4H intensity to _the elemental _{bond Al2O3} intensity at that _position ( _Al2O4H / _Al2O3 ) were determined. These results are summarized in Table ₂ .

[FT-IR analysis]
The barrier films of Examples 1 to 3 and Comparative Example 1 were measured by reflection ATR from the vapor-deposited film surface side of the barrier film using an FT-IR spectrometer (FT-610, manufactured by JASCO Corporation) under the following measurement conditions, and the difference spectrum from the FT-IR of the substrate alone was determined. The measurement results are shown in Figures 13 and 14 and Table 3.

FT-IR measurement conditions: Supply gas: Nitrogen purge with nitrogen gas; ATR crystal: Germanium Ge (wave number range 5500-600 cm ⁻¹ , penetration depth 0.7 μm)
・Resolution: 4cm ^-1
Incident angle: 45 degrees Measurement temperature: room temperature Number of measurements: 128 Measurement method for PET substrate for difference calculation (measure the back side with the stretching direction aligned, and measure the difference so that the peak at 1410 cm ⁻¹ is minimized)

(Evaluation of Barrier Properties)
The water vapor permeability and oxygen permeability of each of the barrier films of Examples 1 to 5 and Comparative Examples 1 to 3 produced by the above-mentioned method were measured.

Water vapor permeability was measured using a water vapor permeability measuring device (manufactured by Mocon, product name "Permatran") at 40°C and 100% RH in accordance with JIS K 7129 Method B. Oxygen permeability was measured using an oxygen permeability measuring device (manufactured by Mocon, product name "OXTRAN") at 23°C and 90% RH in accordance with JIS K 7126-2. The results are shown in Table 4.

(Evaluation of Adhesion)
A two-component curing polyurethane-based laminating adhesive was coated onto the vapor-deposited film 2 of each of the barrier films of Examples 1 to 5 and Comparative Examples 1 to 3 produced by the above method using a gravure roll coating method to a thickness of 4.0 g/m ² (in a dry state) to form an adhesive layer 4, and then a 15 μm-thick biaxially oriented nylon 6 film was placed facing the surface of the adhesive layer 4 as a second substrate 5 and laminated by dry lamination. Next, an adhesive layer 6 for lamination was formed on the surface of the second substrate 5 in the same manner as the adhesive layer 4, and then a 70 μm-thick unstretched polypropylene film was dry laminated onto the surface of the adhesive layer 6 as a sealant layer 7 to produce a laminate having the layer configuration shown in FIG.

Next, the laminates with this layer configuration were placed so that the sealant layers faced each other and heat-sealed to form pouches. The pouches were filled with water and then retorted at 135°C for 40 minutes. The water peel strength of each laminate after retort treatment was measured. The results are summarized in Table 4.

Water peel strength was measured using the following method. First, each laminate after retort treatment was cut into strips to obtain rectangular test pieces with a width of 15 mm. Next, the vapor-deposited film of each test piece was partially peeled away from the substrate along the length of the test piece (the direction perpendicular to the width of the test piece). The peeling was performed so that the vapor-deposited film and the substrate remained partially bonded. Next, using a Tensilon universal testing machine in accordance with JIS Z6854-2, the peel strength of the interface between the vapor-deposited film and the substrate was measured at a peel angle of 180° and a peel rate of 50 mm/min. Water was dropped with a dropper onto the boundary between the portion where the vapor-deposited film and the substrate remained bonded and the portion where the vapor-deposited film and the substrate were peeled away along the length of the test piece. The tensile force required to peel the film over a 30 mm distance was measured, and the average tensile force was calculated. For each of Examples 1 to 5 and Comparative Examples 1 to 3, the average tensile strength was calculated for five test pieces, and this average was used as the water-welded peel strength (adhesion) for each of Examples 1 to 5 and Comparative Examples 1 to 3. The results are shown in Table 4.

As can be seen from Tables 2 and 4, Examples 1 to 3, in which the ratio of the intensity of elemental bond Al ₂ O _{4 H} to the intensity of elemental bond Al ₂ O 3 (Al ₂ O ₄ H/Al ₂ O ₃ ) measured by TOF-SIMS at a position 1/3 from the surface of the deposited film is within the range of the present invention, have higher barrier properties than Comparative Examples 1 to 3.

Furthermore, as can be seen from Tables 2 and 4, Examples 1 to 5, in which the intensity derived from the element bond Al ₂ O ₄ H has a maximum peak at a depth of 55% to 95% from the surface of the deposited film by TOF-SIMS, have higher barrier properties than Comparative Examples 1 to 3.

Furthermore, Tables 3 and 4 show that Examples 1 to 3, in which an absorption peak at 940 cm ⁻¹ or more and 960 cm ⁻¹ or less due to Al—O bonds is present by FT-IR, and the ratio of the absorption intensity of the absorption peak at 3,350 cm ^{−1 or} more and 3,550 cm ⁻¹ or less due to OH bonds to the absorption intensity of the absorption peak at 940 cm ⁻¹ or more and 960 cm −1 or less due to Al—O bonds is within the range of the present invention, have higher barrier properties than Comparative Example 1.

1 Substrate 2 Vapor deposition film 4 Adhesive layer 5 Second substrate 6 Adhesive layer 7 Sealant layer 10 Film formation device P Plasma X Rotary shaft 11A Substrate transport mechanism 11B Plasma pretreatment mechanism 11C Film formation mechanism 12 Decompression chamber 12A Substrate transport chamber 12B Plasma pretreatment chamber 12C Film formation chamber 13 Unwinding roller 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 formation roller 31 Power supply wiring 32 Power sources 35a-35c Partition wall 50 Plasma supply mechanism 51 Hollow cathode 61 Vapor deposition material supply section 63 Aluminum vapor

Claims (5)

A barrier film comprising a substrate and an aluminum oxide vapor-deposited film laminated in this order,
When the aluminum oxide vapor-deposited film is etched from the vapor-deposited film surface side of the barrier film by time-of-flight secondary ion mass spectrometry (TOF-SIMS), intensities derived from elemental bonds Al ₂ O ₃ and elemental bonds Al ₂ O ₄ H are detected,
the aluminum oxide vapor-deposited film has an intensity _ratio ( _Al2O4H / _{Al2O3 )} of the elemental bond _Al2O4H to the elemental bond _Al2O3 , detected at a depth position of 1/3 from the surface of the vapor-deposited film in the _{film thickness} direction, of 0.30 or less;
A barrier film, wherein the intensity derived from the element bond Al ₂ O ₄ H has a maximum peak, and the maximum peak is present at a depth position of 55% to 95% from the surface of the vapor-deposited film. The aluminum oxide vapor-deposited film has an infrared absorption spectrum from the vapor-deposited film surface side of the barrier film,
2. The barrier film according to claim 1, wherein an absorption peak attributable to an Al—O bond is present at 940 cm ⁻¹ or more and 960 cm ⁻¹ or less. 3. The barrier film according to claim 2 , wherein the ratio of the absorption intensity of the absorption peak in the range of 3,350 cm ⁻¹ to 3,550 cm ⁻¹ derived from an O-H bond to the absorption intensity of the absorption peak in the range of 940 cm ⁻¹ to 960 cm ⁻¹ derived from an Al—O bond is 0.20 or less. A laminate comprising the barrier film according to any one of claims 1 to 3 and a sealant layer. A packaging product comprising the laminate described in claim 4.