JP7561331B2 - BARRIER LAMINATE FILM, METHOD FOR PRODUCING BARRIER LAMINATE FILM, AND PACKAGING MATERIAL COMPRISING BARRIER LAMINATE FILM - Google Patents

Description

The present invention relates to a barrier laminate film having a substrate and a vapor deposition layer provided on the substrate, and a method for producing the barrier laminate film. The present invention also relates to a packaging material comprising a barrier laminate film and a thermoplastic resin layer laminated on the barrier laminate film.

Traditionally, various packaging materials have been developed and proposed for filling and packaging various items such as food and beverages, pharmaceuticals, chemicals, cosmetics, and others. Such packaging materials are required to have various physical properties, depending on the purpose of packaging, the contents to be filled, the storage and distribution of the packaged product, and other factors. For example, one of those physical properties is gas barrier properties that prevent the transmission of oxygen, water vapor, etc.

A variety of gas barrier materials that prevent the permeation of oxygen, water vapor, etc. have been developed and proposed. For example, gas barrier materials such as aluminum foil, nylon film or polyethylene terephthalate film with a coating film of polyvinylidene chloride resin, polyvinyl alcohol film, saponified ethylene-vinyl acetate copolymer film, polyacrylonitrile resin film, etc. have been developed and proposed.

Furthermore, in recent years, transparent barrier films have been proposed that have a vapor-deposited layer of an inorganic oxide, such as silicon oxide or aluminum oxide, on a plastic substrate, or a vapor-deposited layer of a metal, such as aluminum. For example, Patent Document 1 proposes producing a barrier film by forming a vapor-deposited layer of an inorganic oxide on a nylon film.

JP 2007-303000 A

Packaging materials are required to have a property that prevents the packaging bag from being torn even when a sharp-edged object comes into contact with the bag, i.e., puncture resistance. The nylon film described in Patent Document 1 is known as a film that has high puncture resistance. On the other hand, nylon is prone to absorbing moisture and has poor heat resistance. Therefore, it is difficult to use nylon film as a film that constitutes the outer surface of a packaging material. For example, in Patent Document 1, a base film containing a polyester resin or the like is laminated on the outer surface side of the nylon film via an adhesive layer. In this way, the packaging material contains two plastic films, the nylon film and the base film, which increases the cost of the packaging material.

The present invention aims to provide a barrier laminate film that can effectively solve these problems.

The present invention is a barrier laminate film comprising a substrate and a vapor deposition layer containing a metal or an inorganic compound provided on the substrate, the substrate having a loop stiffness of 0.0017 N or more in the machine direction and the perpendicular direction, containing polyester as a main component, the tensile strength of the substrate divided by the tensile elongation in at least one direction being 2.0 [MPa/%] or more, and the thickness of the substrate being 16 μm or more and 25 μm or less.

In the barrier laminate film according to the present invention, the puncture strength of the substrate may be 9.5 N or more.

The barrier laminate film according to the present invention may further include a gas barrier coating film provided on the deposition layer.

In the barrier laminate film according to the present invention, the vapor deposition layer may be a transparent vapor deposition layer containing an inorganic compound.

In the barrier laminate film according to the present invention, the vapor deposition layer is a transparent vapor deposition layer containing aluminum oxide, and the transparent vapor deposition layer includes a transition region, which is a region between the position of the peak of elemental bond Al ₂ O ₄ H detected by etching the vapor deposition film from the transparent vapor deposition layer side using time-of-flight secondary ion mass spectrometry (TOF-SIMS) and the interface between the transparent vapor deposition layer and the first plastic film, and the ratio of the thickness of the transition region to the thickness of the transparent vapor deposition layer may be 5% or more and 60% or less.

The present invention is a method for producing a barrier laminate film, comprising a step of preparing a substrate, and a deposition step of depositing a metal or inorganic compound on the substrate to form a deposition layer on the substrate, the substrate having a loop stiffness of 0.0017 N or more in the machine direction and in the perpendicular direction, containing polyester as a main component, a value obtained by dividing the tensile strength of the substrate by the tensile elongation of the substrate in at least one direction being 2.0 [MPa/%] or more, and a thickness of the substrate being 16 μm or more and 25 μm or less.

The method for producing a barrier laminate film according to the present invention may further include a plasma pretreatment step of subjecting the substrate to a plasma treatment to form a plasma-treated surface on the substrate, and the deposition step may form the deposition layer on the plasma-treated surface of the substrate.

In the method for producing a barrier laminate film according to the present invention, the deposition step may form the deposition layer on the plasma-treated surface of the substrate by physical deposition.

In the method for producing a barrier laminate film according to the present invention, the plasma pretreatment step includes a step of supplying a mixed gas of oxygen gas and an inert gas as a plasma raw material gas, and the mixture ratio of the oxygen gas to the inert gas (oxygen gas/inert gas) may be within a range of 6/1 to 1/1.

In the method for producing a barrier laminate film according to the present invention, the deposition layer is a transparent deposition layer containing an inorganic compound, and the film production method may further include a step of forming a gas barrier coating film by applying a coating agent for a gas barrier coating film onto the deposition layer and drying by heating.

In the method for producing a barrier laminate film according to the present invention, the gas barrier coating film may be a layer formed by applying a mixed solution of a metal alkoxide and a water-soluble polymer and drying it by heating.

In the method for producing a barrier laminate film according to the present invention, the gas barrier coating film may be a layer formed by applying a mixed solution of a metal alkoxide, a silane coupling agent, and a water-soluble polymer, and then drying the applied solution by heating.

The present invention is a packaging material comprising a substrate, a barrier laminate film having a vapor deposition layer containing a metal or an inorganic compound provided on the substrate, and a thermoplastic resin layer laminated on the barrier laminate film, the substrate having a loop stiffness of 0.0017 N or more in the machine direction and the perpendicular direction, containing polyester as a main component, the tensile strength of the substrate divided by the tensile elongation in at least one direction being 2.0 [MPa/%] or more, and the thickness of the substrate being 16 μm or more and 25 μm or less.

The packaging material according to the present invention may be used for packaging bags for boiling or for retort sterilization.

The present invention provides a barrier laminate film that has gas barrier properties and strength.

1 is a cross-sectional view showing an example of a barrier laminate film according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing another example of a barrier laminate film. FIG. 2 is a plan view showing an example of a loop stiffness measuring device. FIG. 4 is a cross-sectional view of the loop stiffness measuring device of FIG. 3 taken along line V-V. FIG. 1 is a diagram for explaining a process of attaching a test piece to a loop stiffness measuring device. FIG. 13 is a diagram for explaining a step of forming a loop portion in a test piece. FIG. 13 is a diagram for explaining a process of applying a load to a loop portion of a test piece. FIG. 13 is a diagram for explaining a process of applying a load to a loop portion of a test piece. FIG. 1 is a cross-sectional view showing an example of a substrate containing PBT. FIG. 2 is a diagram showing an example of the results of analyzing a vapor-deposited layer of a barrier laminate film using a time-of-flight secondary ion mass spectrometer. FIG. 1 is a diagram showing an example of a film forming apparatus for forming a deposition layer on a substrate. FIG. 1 is a cross-sectional view showing an example of a packaging material including a barrier laminate film.

The following describes in detail the barrier laminate film and the deposition device for depositing the vapor deposition layer of the barrier laminate film according to the embodiment of the present invention with reference to the drawings. Note that this example is merely illustrative and does not limit the present invention in any way.

<Barrier laminate film>
1 is a cross-sectional view showing an example of a barrier laminate film 5 according to an embodiment of the present invention. The barrier laminate film 5 includes a substrate 1 and a deposition layer 2 provided on the substrate 1.

Figure 2 is a cross-sectional view showing another example of a barrier laminate film 5 according to an embodiment of the present invention. The barrier laminate film 5 includes a substrate 1, a deposition layer 2 provided on the substrate 1, and a gas barrier coating film 3 provided on the deposition layer 2.

Although not shown, the barrier laminate film 5 may further include a printing layer provided on the substrate 1, on the deposition layer 2, or on the gas barrier coating film 3. The printing layer is a layer for displaying product information or imparting an aesthetic feel to a packaging bag made of a packaging material 8 (described later) that includes the barrier laminate film 5. The printing layer expresses letters, numbers, symbols, figures, pictures, etc. Inks for gravure printing or flexographic printing can be used as materials for the printing layer. Finart, manufactured by DIC Graphics Corporation, can be mentioned as a specific example of an ink for gravure printing.

The components of the barrier laminate film 5 are explained below.

[Substrate]
The substrate 1 used in the barrier laminate film 5 is a polyester film containing polyester as a main component. The substrate 1 contains, for example, 51% by mass or more of polyester. The polyester is preferably a polyester mainly composed of an aromatic polyester consisting of at least one aromatic dicarboxylic acid selected from terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid, and at least one aliphatic alcohol selected from ethylene glycol, 1,3-propanediol, and 1,4-butanediol. For example, the polyester is polyethylene terephthalate (hereinafter also referred to as PET), polybutylene terephthalate (hereinafter also referred to as PBT), etc. For example, the substrate 1 may contain 51% by mass or more of PET as a main component, or may contain 51% by mass or more of PBT as a main component.

In order to prevent a packaging bag made of a packaging material including the barrier laminate film 5 from being torn when a sharp member with a pointed tip comes into contact with the bag, it is preferable that the substrate 1 of the barrier laminate film 5 has resistance such as puncture resistance. Therefore, in this embodiment, it is proposed to use either a high-stiffness PET film or a PBT film as the substrate 1. This can increase the puncture strength of the substrate 1, for example. For example, the puncture strength of the substrate 1 can be 9.5 N or more, and more preferably 10 N or more. In addition, the ratio of the tensile strength to the tensile elongation of the substrate 1 can be increased. For example, the value obtained by dividing the tensile strength of the substrate by the tensile elongation in at least one direction is 2.0 [MPa/%] or more. This can provide the packaging material including the barrier laminate film 5 with the rigidity to prevent the bag from being torn even when a sharp member with a pointed tip comes into contact with the packaging material.

The high stiffness PET film and PBT film are explained in detail below. First, the high stiffness PET film is explained.

A high-stiffness PET film is a stretched plastic film that has a loop stiffness of 0.0017 N or more in the machine direction (MD) and the perpendicular direction (TD) and contains 51% or more by mass of PET. The thickness of the high-stiffness PET film is preferably 5 μm or more, and more preferably 7 μm or more. The thickness of the high-stiffness PET film is preferably 25 μm or less, and more preferably 20 μm or less.

Loop stiffness is a parameter that indicates the stiffness of a film. Below, we will explain how to measure loop stiffness with reference to Figures 3 to 8.

The measurement method described below can be used not only for single-layer films such as stretched plastic films, but also for films with multiple layers such as vapor-deposited films and laminated films. A vapor-deposited film is a film that includes a single-layer film and a vapor-deposited layer formed on the single-layer film, such as the barrier laminated film 5 described above. A laminated film is a film that includes multiple laminated films, such as the packaging material 8 described below.

Figure 3 is a plan view showing the test piece 40 and the loop stiffness measuring instrument 45, and Figure 4 is a cross-sectional view of the test piece 40 and the loop stiffness measuring instrument 45 of Figure 3 taken along line IV-IV. The test piece 40 is a rectangular film having long and short sides. In this application, the length L1 of the long side of the test piece 40 is set to 150 mm, and the length L2 of the short side is set to 15 mm. As the loop stiffness measuring instrument 45, for example, No. 581 Loop Stiffness Tester (registered trademark) LOOP STIFFNESS TESTER DA type manufactured by Toyo Seiki Seisakusho Co., Ltd. can be used. The length L1 of the long side of the test piece 40 can be adjusted as long as the test piece 40 can be gripped by a pair of chuck parts 46 described later.

The loop stiffness measuring device 45 has a pair of chucks 46 for gripping a pair of ends in the long side direction of the test piece 40, and a support member 47 for supporting the chucks 46. The chucks 46 include a first chuck 461 and a second chuck 462. In the state shown in FIG. 3 and FIG. 4, the test piece 40 is placed on the pair of first chucks 461, and the second chuck 462 does not yet grip the test piece 40 between the first chuck 461 and the second chuck 462. As described later, during measurement, the test piece 40 is gripped between the first chuck 461 and the second chuck 462 of the chucks 46. The second chuck 462 may be connected to the first chuck 461 via a hinge mechanism.

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

A method for measuring the loop stiffness of the test piece 40 using the loop stiffness measuring device 45 will be described. First, as shown in FIG. 3 and FIG. 4, the test piece 40 is placed on the first chuck 461 of the pair of chuck parts 46 arranged with a gap L3 therebetween. In this application, the gap L3 is set so that the length of the loop part 41 (hereinafter also referred to as the loop length) described later is 60 mm. The test piece 40 includes an inner surface 40x located on the first chuck 461 side and an outer surface 40y located on the opposite side of the inner surface 40x. When the test piece 40 is made of a packaging material, the inner surface 40x and the outer surface 40y of the test piece 40 coincide with the inner surface and the outer surface of the packaging material. Next, as shown in FIG. 5, the second chuck 462 is placed on the test piece 40 so as to grip the end of the long side direction of the test piece 40 between the first chuck 461 and the second chuck 462.

Next, as shown in FIG. 6, at least one of the pair of chucks 46 is slid on the support member 47 in a direction in which the distance between the pair of chucks 46 is reduced. This allows the loop portion 41 to be formed on the test piece 40. The test piece 40 shown in FIG. 6 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 piece 40 that are gripped by the pair of chucks 46. The pair of intermediate portions 42 are portions of the test piece 40 that are located between the loop portion 41 and the pair of intermediate portions 42. As shown in FIG. 6, 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 the loop portion 41 to be formed with a loop length of 60 mm. The loop length of the loop portion 41 is the length of the test piece 40 between position P1 where the surface of the loop portion 41 side of one second chuck 462 intersects with the test piece 40, and position P2 where the surface of the loop portion 41 side of the other second chuck 462 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×t to the length of the loop portion 41. t is the thickness of the second chuck 462 of the chuck portion 46.

7, 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. 7, the protruding direction Y of the loop portion 41 coincides with the thickness direction of the chuck portion. In addition, the load cell 48 is prepared at a position 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 by the distance Z2 shown in FIG. 7 toward the loop portion 41 of the test piece 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 side, as shown in FIG. 7 and FIG. 8. In this application, the distance Z2 is set to 40 mm. In this case, the distance Z3 between the load cell 48 and the second chuck 462 of the chuck portion 46 when the load cell 48 is pushing the loop portion 41 toward the chuck portion 46 is 10 mm. The speed V at which the load cell 48 is moved is 3.3 mm/sec.

Next, as shown in FIG. 8, the load cell 48 is moved a distance Z2 toward the chuck portion 46, and in the state where the load cell 48 is pressing the loop portion 41 of the test piece 40, the value of the load applied to the load cell 48 from the loop portion 41 becomes stable, and then the value of the load is recorded. The value of the load thus obtained is used as the loop stiffness of the film constituting the test piece 40. In this application, unless otherwise specified, the environment during the measurement of the loop stiffness is a temperature of 23°C and a relative humidity of 50%.

The preferred mechanical properties of the high stiffness PET film will now be further described.
The puncture strength of the high stiffness PET film is preferably 9.5 N or more, and more preferably 10.0 N or more.

The tensile strength of the high stiffness PET film in the machine direction is preferably 250 MPa or more, more preferably 280 MPa or more. The tensile strength of the high stiffness PET film in the perpendicular direction is preferably 250 MPa or more, more preferably 280 MPa or more.
The tensile elongation of the high stiffness PET film in the machine direction is preferably 130% or less, more preferably 120% or less. The tensile elongation of the high stiffness PET film in the perpendicular direction is preferably 120% or less, more preferably 110% or less.
As described above, the tensile strength of the high stiffness PET film divided by the tensile elongation in at least one direction is preferably 2.0 [MPa/%] or more. 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 more, more preferably 2.2 [MPa/%] or more. The tensile strength of the high stiffness film divided by the tensile elongation in the machine direction (MD) is preferably 1.8 [MPa/%] or more, more preferably 2.0 [MPa/%] or more.
The tensile strength and tensile elongation can be measured in accordance with JIS K7127. As a measuring instrument, a tensile tester STA-1150 manufactured by Orientec Co., Ltd. can be used. As a test piece, a rectangular film cut from a high stiffness PET film having a width of 15 mm and a length of 150 mm can be used. The distance between a pair of chucks holding the test piece at the start of the measurement is 100 mm, and the tensile speed is 300 mm/min. The environmental temperature during the test is 25°C, and the relative humidity is 50%. The tensile strength and tensile elongation of the barrier laminate film 5 including the high stiffness PET film, the tensile strength and tensile elongation of the PBT film, and the tensile strength and tensile elongation of the barrier laminate film 5 including the PBT film are also measured in the same manner as in the case of the high stiffness PET film.

The heat shrinkage of the high stiffness PET film in the machine direction is preferably 0.7% or less, more preferably 0.5% or less. The heat shrinkage of the high stiffness PET 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 PET film in the machine direction is preferably 4.0 GPa or more, more preferably 4.5 MPa or more, and the Young's modulus of the high stiffness PET film in the perpendicular direction is preferably 4.0 GPa or more, more preferably 4.5 GPa or more.

In the manufacturing process of high stiffness PET film, for example, first, a first stretching process is carried out in which a PET film obtained by melting and molding polyethylene terephthalate is stretched 3 to 4.5 times in the machine direction and perpendicular direction at 90°C to 145°C. Then, a second stretching process is carried out in which the plastic film is stretched 1.1 to 3.0 times in the machine direction and perpendicular direction at 100°C to 145°C. Then, heat setting is carried out at a temperature of 190°C to 220°C. Next, relaxation treatment (treatment to reduce the film width) of about 0.2% to 2.5% is carried out at a temperature of 100°C to 190°C in the machine direction and perpendicular direction. In these processes, by adjusting the stretch ratio, stretching temperature, heat setting temperature, and relaxation treatment rate, a high stiffness PET film with the above-mentioned mechanical properties can be obtained.

Next, preferred mechanical properties of the barrier laminate film 5 having the above-mentioned high stiffness PET film as the substrate 1 will be further described.
The barrier laminate film 5 preferably has a loop stiffness of 0.0017 N or more in both the machine direction (MD) and the transverse direction (TD).
The puncture strength of the barrier laminate film 5 is preferably 9.5 N or more, and more preferably 10.0 N or more.
The tensile strength of the barrier laminate film 5 in the machine direction is preferably 250 MPa or more, more preferably 280 MPa or more. The tensile strength of the barrier laminate film 5 in the perpendicular direction is preferably 250 MPa or more, more preferably 280 MPa or more.
The tensile elongation of the barrier laminate film 5 in the machine direction is preferably 130% or less, more preferably 120% or less. The tensile elongation of the barrier laminate film 5 in the perpendicular direction is preferably 120% or less, more preferably 110% or less.
Preferably, in at least one direction, the value obtained by dividing the tensile strength of the barrier laminate film 5 by the tensile elongation is 2.0 [MPa/%] or more. For example, the value obtained by dividing the tensile strength of the barrier laminate film 5 by the tensile elongation in the transverse direction (TD) is preferably 2.0 [MPa/%] or more, more preferably 2.2 [MPa/%] or more. The value obtained by dividing the tensile strength of the barrier laminate film 5 by the tensile elongation in the machine direction (MD) is preferably 1.8 [MPa/%] or more, more preferably 2.0 [MPa/%] or more.
The thermal shrinkage of the barrier laminate film 5 in the machine direction is preferably 0.7% or less, more preferably 0.5% or less. The thermal shrinkage of the barrier laminate film 5 in the perpendicular direction is preferably 0.7% or less, more preferably 0.5% or less. The heating temperature for measuring the thermal shrinkage is 100° C., and the heating time is 40 minutes.
The Young's modulus of the barrier laminate film 5 in the machine direction is preferably 4.0 GPa or more, more preferably 4.5 MPa or more. The Young's modulus of the barrier laminate film 5 in the perpendicular direction is preferably 4.0 GPa or more, more preferably 4.5 GPa or more.

The PET constituting the high-stiffness PET film may contain biomass-derived PET. In this case, the high-stiffness PET film may be composed only of biomass-derived PET. Alternatively, the high-stiffness PET film may be composed of biomass-derived PET and fossil fuel-derived PET. By including biomass-derived PET in the high-stiffness PET film, the amount of fossil fuel-derived PET can be reduced compared to the conventional method, so that carbon dioxide emissions can be reduced and the environmental load can be reduced. Note that the biomass-derived PET has ethylene glycol derived from biomass as the diol unit and terephthalic acid derived from fossil fuel as the dicarboxylic acid unit. The fossil fuel-derived PET has ethylene glycol derived from fossil fuel as the diol unit and terephthalic acid derived from fossil fuel as the dicarboxylic acid unit.

Since atmospheric carbon dioxide contains a certain percentage of C14 (105.5 pMC), it is known that the C14 content in plants that grow by absorbing atmospheric carbon dioxide, such as corn, is also about 105.5 pMC. It is also known that fossil fuels contain almost no C14. Therefore, by measuring the percentage of C14 in the total carbon atoms in PET, the percentage of carbon derived from biomass can be calculated. In the present invention, the "biomass degree" indicates the weight ratio of biomass-derived components. Taking PET as an example, PET is a polymer of ethylene glycol containing 2 carbon atoms and terephthalic acid containing 8 carbon atoms in a molar ratio of 1:1. If only biomass-derived ethylene glycol is used for PET, the weight ratio of biomass-derived components in PET is 31.25%, so the theoretical value of the biomass degree of PET is 31.25%. Specifically, the mass of PET is 192, of which the mass derived from biomass-derived ethylene glycol is 60, so 60÷192×100=31.25. The weight ratio of biomass-derived components in fossil fuel-derived PET is 0%, and the biomass degree of fossil fuel-derived PET is 0%. In the present invention, the biomass degree of the high stiffness PET film is preferably 5.0% or more, and more preferably 10.0% or more. The biomass degree of the high stiffness PET film is preferably 30.0% or less.

Biomass-derived ethylene glycol is made from ethanol (biomass ethanol) produced from biomass. For example, biomass-derived ethylene glycol can be obtained by a method of producing ethylene glycol from biomass ethanol via ethylene oxide using a conventionally known method. Examples of raw materials for biomass ethanol include corn, sugar cane, beet, and manioc. Commercially available biomass ethylene glycol may also be used, and for example, biomass ethylene glycol commercially available from India Glycoal Limited can be suitably used. Note that India Glycoal Limited's biomass ethylene glycol is made from sugar cane molasses.

Next, we will explain PBT film. PBT film is a stretched plastic film that contains 51% or more by mass of PBT. Below, we will explain the advantages of the substrate 1 containing PBT.

PBT has excellent heat resistance. Therefore, deformation of the substrate 1 or reduction in the strength of the substrate 1 can be suppressed when a packaging bag for containing contents such as food is subjected to a boiling treatment or a retort treatment. Retort treatment is a treatment in which the contents are filled into the packaging bag, the packaging bag is sealed, and then the packaging bag is heated under pressure using steam or heated hot water. The temperature of the retort treatment is, for example, 120°C or higher. Boiling treatment is a treatment in which the contents are filled into the bag 10, the bag 10 is sealed, and then the bag 10 is heated in a water bath under atmospheric pressure. The temperature of the boiling treatment is, for example, 90°C or higher and 100°C or lower.

PBT also has high strength. For this reason, the packaging bag can be made puncture-resistant, just as when the packaging material 8 constituting the packaging bag contains nylon. The puncture strength of the PBT film is preferably 9.5 N or more, and more preferably 10.0 N or more.

The tensile strength of the PBT film in the machine direction is preferably 150 MPa or more, more preferably 180 MPa or more, and the tensile strength of the PBT film in the perpendicular direction is preferably 250 MPa or more, more preferably 280 MPa or more.
The tensile elongation of the PBT film in the machine direction is preferably 220% or less, more preferably 200% or less, and the tensile elongation of the PBT film in the perpendicular direction is preferably 120% or less, more preferably 110% or less.
Preferably, the value of the tensile strength of the PBT film divided by the tensile elongation in at least one direction is 2.0 [MPa/%] or more. For example, the value of the tensile strength of the PBT film divided by the tensile elongation in the transverse direction (TD) is preferably 2.0 [MPa/%] or more, more preferably 2.2 [MPa/%] or more, and even more preferably 2.5 [MPa/%] or more.

In addition, PBT has the characteristic of being less susceptible to moisture absorption than nylon. Therefore, even if a base material 1 containing PBT is placed on the outer surface of a packaging material 8, it is possible to prevent the base material 1 from absorbing moisture, which would cause a decrease in the laminate strength of the packaging material 8.

Next, preferred mechanical properties of the barrier laminate film 5 having the above-mentioned PBT film as the substrate 1 will be further described.
The puncture strength of the barrier laminate film 5 is preferably 9.5 N or more, and more preferably 10.0 N or more.
The tensile strength of the barrier laminate film 5 in the machine direction is preferably 150 MPa or more, more preferably 180 MPa or more. The tensile strength of the barrier laminate film 5 in the perpendicular direction is preferably 250 MPa or more, more preferably 280 MPa or more.
The tensile elongation of the barrier laminate film 5 in the machine direction is preferably 220% or less, more preferably 200% or less. The tensile elongation of the barrier laminate film 5 in the perpendicular direction is preferably 120% or less, more preferably 110% or less.
Preferably, in at least one direction, the value obtained by dividing the tensile strength of the barrier laminate film 5 by the tensile elongation is 2.0 [MPa/%] or more. For example, the value obtained by dividing the tensile strength of the barrier laminate film 5 by the tensile elongation in the perpendicular direction (TD) is preferably 2.0 [MPa/%] or more, more preferably 2.2 [MPa/%] or more, and even more preferably 2.5 [MPa/%] or more.

The configuration of the substrate 1 containing PBT will be described in detail below. In this embodiment, the substrate 1 containing PBT may have either the first or second configuration described below.

[First configuration of the substrate containing PBT]
The content of PBT in the base material 1 according to the first configuration is preferably 51% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, particularly preferably 75% by mass or more, and most preferably 80% by mass or more. By making the content of PBT 51% by mass or more, the base material 1 can have excellent impact strength and pinhole resistance.

The PBT used as the main component preferably contains 90 mol % or more of terephthalic acid as a dicarboxylic acid component, more preferably 95 mol % or more, even more preferably 98 mol % or more, and most preferably 100 mol %. The glycol component preferably contains 90 mol % or more of 1,4-butanediol, more preferably 95 mol % or more, even more preferably 97 mol % or more, and most preferably contains no by-products other than those generated by ether bonds of 1,4-butanediol during polymerization.

The substrate 1 may contain a polyester resin other than PBT. This makes it possible to adjust the film formability and the mechanical properties of the substrate 1 when the film-like substrate 1 is biaxially stretched, for example.
Examples of polyester resins other than PBT include polyester resins such as PET, polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), and polypropylene terephthalate (PPT), as well as PBT resins copolymerized with dicarboxylic acids such as isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyl dicarboxylic acid, cyclohexane dicarboxylic acid, adipic acid, azelaic acid, and sebacic acid, and PBT resins copolymerized with diol components such as ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, cyclohexanediol, polyethylene glycol, polytetramethylene glycol, and polycarbonate diol.

The amount of these polyester resins other than PBT added is preferably 49% by mass or less, and more preferably 40% by mass or less. If the amount of polyester resins other than PBT added exceeds 49% by mass, the mechanical properties of PBT may be impaired, and impact strength, pinhole resistance, and draw formability may become insufficient.

The substrate 1 may contain, as an additive, a polyester-based or polyamide-based elastomer obtained by copolymerizing at least one of a flexible polyether component, a polycarbonate component, and a polyester component. This can improve pinhole resistance when bent. The amount of additive added is, for example, 20% by mass. If the amount of additive added exceeds 20% by mass, the effect of the additive may become saturated, or the transparency of the substrate 1 may decrease.

An example of a method for producing the film-like substrate 1 according to the first configuration will be described. Here, a method for producing the film-like substrate 1 by a casting method will be described. More specifically, a method for casting resins of the same composition in multiple layers will be described.

Since PBT has a high crystallization rate, crystallization proceeds even during casting. In this case, if PBT is cast in a single layer without being multi-layered, there is no barrier that can suppress the growth of the crystals, so the crystals grow to a large size, and the yield stress of the obtained unstretched raw material becomes high. Therefore, the unstretched raw material is easily broken when it is biaxially stretched. In addition, the yield stress of the obtained biaxially stretched film becomes high, and it is considered that the formability of the biaxially stretched film becomes insufficient.
In contrast, if the same resin is multi-layered during casting, the stretching stress of the unstretched sheet can be reduced, allowing stable biaxial stretching and lowering the yield stress of the resulting biaxially stretched film, resulting in a flexible film with high breaking strength.

Figure 9 is a cross-sectional view showing an example of the layer structure of the substrate 1. When the substrate 1 is produced by casting a resin in layers, as shown in Figure 9, the substrate 1 is composed of a multilayer structure including multiple layers 1a. Each of the multiple layers 1a contains PBT as a main component. For example, each of the multiple layers 1a preferably contains 51% by mass or more of PBT, and more preferably 60% by mass or more of PBT. In addition, in the multiple layers 1a, the n+1th layer 1a is directly laminated on the nth layer 1a. In other words, no adhesive layer or bonding layer is interposed between the multiple layers 1a.

The reason why multi-layering improves the properties of PBT film is speculated to be as follows. When resins are layered, even if the resins have the same composition, there is an interface between the layers, and this interface accelerates crystallization. On the other hand, the growth of large crystals that exceed the thickness of the layers is suppressed. This is thought to result in a smaller size of the crystals (spherulites).

Specific methods for reducing the size of spherulites by multi-layering include using general multi-layering devices (multi-layer feed blocks, static mixers, multi-layer multi-manifolds, etc.). For example, a method can be used in which thermoplastic resins discharged from different flow paths using two or more extruders are laminated into multiple layers using a feed block, static mixer, multi-manifold die, etc. When resins of the same composition are multi-layered, it is also possible to use only one extruder and introduce the above-mentioned multi-layering device into the melt line from the extruder to the die.

The substrate 1 is made of a multilayer structure including at least 10 layers 1a, preferably 60 layers or more, more preferably 250 layers or more, and even more preferably 1000 layers or more. By increasing the number of layers, the size of the spherulites in the PBT in the unstretched raw roll can be reduced, and the subsequent biaxial stretching can be performed stably. In addition, the yield stress of the PBT in the biaxially stretched film state can be reduced. Preferably, the diameter of the spherulites in the PBT in the unstretched raw roll is 500 nm or less.

When biaxially stretching an unstretched raw PBT film to produce a biaxially stretched film, the stretching temperature in the longitudinal stretching direction (hereinafter, MD) (hereinafter, also referred to as MD stretching temperature) is preferably 40°C or higher, more preferably 45°C or higher. By setting the MD stretching temperature at 40°C or higher, it is possible to prevent the film from breaking. In addition, the MD stretching temperature is preferably 100°C or lower, more preferably 95°C or lower. By setting the MD stretching temperature at 100°C or lower, it is possible to prevent the phenomenon in which the biaxially stretched film does not become oriented.

The stretch ratio in the MD (hereinafter also referred to as the MD stretch ratio) is preferably 2.5 times or more. This allows the biaxially stretched film to be oriented, resulting in good mechanical properties and a uniform thickness. The MD stretch ratio is, for example, 5 times or less.

The stretching temperature in the transverse stretching direction (hereinafter also referred to as TD) (hereinafter also referred to as TD stretching temperature) is preferably 40°C or higher. By setting the TD stretching temperature at 40°C or higher, it is possible to prevent the film from breaking. In addition, the TD stretching temperature is preferably 100°C or lower. By setting the TD stretching temperature at 100°C or lower, it is possible to prevent the phenomenon in which the biaxially stretched film does not become oriented.

The stretch ratio in the TD (hereinafter also referred to as the TD stretch ratio) is preferably 2.5 times or more. This allows the biaxially stretched film to be oriented, resulting in good mechanical properties and a uniform thickness. The MD stretch ratio is, for example, 5 times or less.

The TD relaxation ratio is preferably 0.5% or more. This can prevent the biaxially stretched PBT film from breaking during heat setting. In addition, the TD relaxation ratio is preferably 10% or less. This can prevent the biaxially stretched PBT film from becoming slack and causing thickness unevenness.

The thickness of the layer 1a of the substrate 1 shown in Fig. 9 is preferably 3 nm or more, more preferably 10 nm or more. The thickness of the layer 1a is preferably 200 nm or less, more preferably 100 nm or less.
The thickness of the substrate 1 is preferably 9 μm or more, more preferably 12 μm or more. The thickness of the substrate 1 is preferably 25 μm or less, more preferably 20 μm or less. By making the thickness of the substrate 1 9 μm or more, the substrate 1 has sufficient strength. By making the thickness of the substrate 1 25 μm or less, the substrate 1 exhibits excellent formability. Therefore, the process of manufacturing a packaging bag by processing the packaging material 8 including the substrate 1 can be efficiently carried out.

[Second configuration of the substrate containing PBT]
The substrate 1 according to the second configuration is made of a monolayer film containing a polyester having butylene terephthalate as the main repeating unit. For example, the substrate 1 contains a homo- or copolymer-type polyester obtained by condensing 1,4-butanediol or its ester-forming derivative as a glycol component and terephthalic acid or its ester-forming derivative as a dibasic acid component. The content of PBT in the substrate 1 according to the second configuration is preferably 51% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and most preferably 90% by mass or more. The substrate 1 according to the second configuration is preferably composed of only polybutylene terephthalate and additives.

In order to impart mechanical strength to the substrate 1, it is preferable for the PBT to have a melting point of 200°C or more and 250°C or less, and an IV value (intrinsic viscosity) of 1.10 dl/g or more and 1.35 dl/g or less. Furthermore, it is particularly preferable for the PBT to have a melting point of 215°C or more and 225°C or less, and an IV value of 1.15 dl/g or more and 1.30 dl/g or less. These IV values may be satisfied by the entire material constituting the substrate 1. The IV value can be calculated based on JIS K 7367-5:2000.

The substrate 1 according to the second configuration may contain polyester resin other than PBT, such as PET, in the range of 30% by mass or less. By containing PET in addition to PBT, the substrate 1 can suppress PBT crystallization, and improve the stretchability of the PBT film. As the PET to be blended with the PBT of the substrate 1, a polyester having ethylene terephthalate as the main repeating unit can be used. For example, a homotype having ethylene glycol as the glycol component and terephthalic acid as the dibasic acid component as the main components can be preferably used. In order to impart good mechanical strength properties, PET having a melting point of 240° C. or more and 265° C. or less and an IV value of 0.55 dl/g or more and 0.90 dl/g or less is preferable. Furthermore, PET having a melting point of 245° C. or more and 260° C. or less and an IV value of 0.60 dl/g or more and 0.80 dl/g or less is particularly preferable.
By making the blending amount of PET 30% by mass or less, it is possible to prevent the rigidity of the unstretched raw material and the stretched film from becoming too high. This makes it possible to prevent the stretched film from becoming brittle, which leads to a decrease in the pressure resistance, impact strength, puncture strength, etc. of the stretched film. It is also possible to prevent the occurrence of stretching problems when stretching the unstretched raw material.

The substrate 1 may contain additives such as lubricants, antiblocking agents, inorganic bulking agents, antioxidants, UV absorbers, antistatic agents, flame retardants, plasticizers, colorants, crystallization inhibitors, and crystallization accelerators, as necessary. In addition, the polyester resin pellets used as the raw material for the substrate 1 are preferably pre-dried sufficiently before heat melting so that the moisture content is 0.05% by weight or less, preferably 0.01% by weight or less, in order to avoid a decrease in viscosity due to hydrolysis during heat melting.

An example of a method for producing the film-like substrate 1 according to the second configuration will be described.

In order to stably produce a film of the substrate 1 having the above-mentioned configuration, it is important to suppress the growth of crystals in the unstretched raw roll. Specifically, when the extruded PBT melt is cooled to form a film, the crystallization temperature range of the polymer is cooled at a certain rate or higher, that is, the raw roll cooling rate is an important factor. The raw roll cooling rate is, for example, 200°C/sec or higher, preferably 250°C/sec or higher, and particularly preferably 350°C/sec or higher. The unstretched raw roll formed into a film at a high cooling rate maintains a low crystallinity state, improving the stability of the bubble during stretching. Furthermore, high-speed film formation is also possible, improving the productivity of the film. If the cooling rate is less than 200°C/sec, the crystallinity of the obtained unstretched raw roll is likely to be high and the stretchability is likely to be reduced. In extreme cases, the stretching bubble may burst and the stretching may not continue.

It is preferable that the unstretched raw material containing PBT as the main component is transported to the space where the biaxial stretching is performed while maintaining the ambient temperature at 25°C or less, preferably 20°C or less. This makes it possible to maintain the crystallinity of the unstretched raw material immediately after film formation, even if the residence time is long.

The biaxial stretching method for stretching the unstretched raw material to obtain a stretched film is not particularly limited. For example, the film may be stretched in the longitudinal and transverse directions simultaneously by the tubular method or tenter method, or may be stretched in the longitudinal and transverse directions sequentially. Of these, the tubular method is particularly preferred because it can obtain a stretched film with a good balance of physical properties in the circumferential direction.

In the tubular method, the unstretched raw film introduced into the stretching space is passed between a pair of low-speed nip rolls, and then heated by a stretching heater while air is forced into the nip rolls. After the stretching is completed, air is blown onto the stretched film by a cooling shoulder air ring. In consideration of the stretching stability and the strength properties, transparency, and thickness uniformity of the stretched film, the stretching ratio is preferably 2.7 times or more and 4.5 times or less in both MD and TD. By setting the stretching ratio to 2.7 times or more, the tensile modulus and impact strength of the stretched film can be sufficiently ensured. In addition, by setting the stretching ratio to 4.5 times or less, excessive strain of the molecular chain due to stretching can be suppressed, and breakage or puncture during stretching can be suppressed, so that the stretched film can be stably produced.

The stretching temperature is preferably 40°C or higher and 80°C or lower, and particularly preferably 45°C or higher and 65°C or lower. The unstretched raw roll produced at the above-mentioned high cooling rate has low crystallinity, so even if the stretching temperature is relatively low, the unstretched raw roll can be stably stretched. Furthermore, by setting the stretching temperature to 80°C or lower, the shaking of the stretching bubble can be suppressed, and a stretched film with good thickness accuracy can be obtained. Furthermore, by setting the stretching temperature to 40°C or higher, excessive stretch-oriented crystallization caused by low-temperature stretching can be suppressed, and whitening of the film can be prevented.

The substrate 1 produced as described above is composed of a single layer containing, for example, a polyester whose main repeating unit is butylene terephthalate. According to the above-mentioned production method, the unstretched raw roll is formed at a high cooling rate, so that even if the unstretched raw roll is composed of a single layer, it is possible to maintain a low crystallinity state, and therefore the unstretched raw roll can be stably stretched.

By including PBT in the substrate 1, the heat resistance of the barrier laminate film 5 and the packaging material 8 including the barrier laminate film 5 can be increased. For example, the tensile modulus of the barrier laminate film 5 and the packaging material 8 can be sufficiently increased. In particular, the tensile modulus of the barrier laminate film 5 and the packaging material 8 in a high-temperature atmosphere, for example, an atmosphere of 100°C (hereinafter also referred to as hot tensile modulus) can be sufficiently increased.

[Deposition layer]
Next, the deposition layer 2 will be described.

The deposition layer 2 is a thin film that has gas barrier properties that prevent or block the transmission of oxygen gas, water vapor, and the like. The deposition layer 2 may be a metal layer that contains a metal with light-shielding properties such as aluminum, or may be a transparent deposition layer formed from a transparent inorganic compound. For example, the deposition layer 2 is a transparent deposition layer formed from a transparent inorganic oxide.

Hereinafter, a case where the deposition layer 2 is a transparent deposition layer will be described. The inorganic oxide forming the deposition layer 2 contains, as a main component, an aluminum compound, such as at least aluminum oxide, or aluminum nitride, carbide, or hydroxide, either alone or in combination. For example, the inorganic oxide contains aluminum oxide as a main component.
The deposition layer 2 may also be a layer containing a silicon compound as a main component. For example, the inorganic oxide layer contains silicon oxide (silicon oxide) as a main component.
Furthermore, the deposition layer 2 may be a layer containing an aluminum compound such as the above-mentioned aluminum oxide as a main component, and further containing a metal oxide such as silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, magnesium oxide, titanium oxide, tin oxide, indium oxide, zinc oxide, zirconium oxide, or the like, or a nitride or carbide of these metals, or a mixture thereof.

The thickness of the deposition layer 2 is preferably 3 nm or more and 50 nm or less, and more preferably 9 nm or more and 30 nm or less.

(Gas barrier coating film)
The gas barrier coating film 3 serves to mechanically and chemically protect the deposition layer 2 when the deposition layer 2 is a transparent deposition layer, and to improve the barrier properties of the barrier laminate film 5, and is laminated so as to be in contact with the deposition layer 2. The gas barrier coating film 3 is a cured film formed from a coating agent for gas barrier coating films, which is made of a resin composition containing a metal alkoxide, a hydroxyl group-containing water-soluble resin, and a silane coupling agent added as necessary.

The mass ratio of the hydroxyl-containing water-soluble resin to the metal alkoxide in the resin composition is preferably 5/95 or more and 20/80 or less, and more preferably 8/92 or more and 15/85 or less. If it is smaller than the above range, the barrier effect of the barrier coating layer tends to be insufficient, and if it is larger than the above range, the rigidity and brittleness of the barrier coating layer tends to be large.

The thickness of the gas barrier coating film 3 is preferably 100 nm or more and 800 nm or less. If it is thinner than the above range, the barrier effect of the gas barrier coating film 3 is likely to be insufficient, and if it is thicker than the above range, it is likely to become too rigid and brittle.

Metal alkoxides are represented by the general formula R ₁ nM(OR ₂ ) m (wherein, R ₁ and R ₂ represent a hydrogen atom or an organic group having 1 to 8 carbon atoms, M represents a metal atom, n represents an integer of 0 or more, m represents an integer of 1 or more, and n+m represents the atomic valence of M. Multiple R _{1 s} and R _{2 s} in one molecule may be the same or different) (I).

Specific examples of metal atoms represented by M in metal alkoxides include silicon, zirconium, titanium, aluminum, tin, lead, borane, and others. For example, it is preferable to use an alkoxysilane in which M is Si (silicon).

In the above general formula (I), specific examples of _OR2 include alkoxy groups such as hydroxyl group, methoxy group, ethoxy group, n-propoxy group, n-butoxy group, i-propoxy group, butoxy group, 3-methacryloxy group, 3-acryloxy group, and phenoxy group, and the like.

In the above, specific examples of R ₁ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a phenyl group, a p-styryl group, a 3-chloropropyl group, a trifluoromethyl group, a vinyl group, a γ-glycidoxypropyl group, a methacryl group, and a γ-aminopropyl group.

Specific examples of alkoxysilanes include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, tetrabutoxysilane, tetraphenoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, methyltriphenoxysilane, phenylphenoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, isopropyltrimethoxysilane, isopropyltriethoxysilane, dimethyldiethoxysilane, and diphenyldimethoxysilane. Examples of the alkoxysilane include various alkoxysilanes and phenoxysilanes such as silane, diphenyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, 3-chloropropyltriethoxysilane, trifluoromethyltrimethoxysilane, and 1,6-bis(trimethoxysilyl)hexane. In the present embodiment, condensation polymers of these alkoxysilanes can also be used, and specifically, for example, polytetramethoxysilane, polytetraethoxysilane, etc. can be used.

Silane coupling agents are used to adjust the crosslink density of the cured film made of metal alkoxide and hydroxyl-containing water-soluble resin, to create a film with barrier properties and resistance to hot water treatment.

The silane coupling agent has the general formula: R ₃ nSi(OR ₄ ) 4-n (II)
(In the formula, _R3 and _R4 each independently represent an organic functional group, and n is 1 to 3.)
It is expressed as:

In the above general formula (II), R ₃ may be, for example, a hydrocarbon group such as an alkyl group or an alkylene group, an epoxy group, a (meth)acryloxy group, a ureido group, a vinyl group, an amino group, an isocyanurate group, or a functional group having an isocyanate group. Specifically, at least one of the two or three R _3s is preferably a functional group having an epoxy group, more preferably a 3-glycidoxypropyl group or a 2-(3,4 epoxycyclohexyl) group. The R _3s may be the same or different.

In the above general formula (II), R ₄ is, for example, an organic functional group having 1 to 8 carbon atoms, and is preferably an alkyl group having 1 to 8 carbon atoms or an alkoxyalkyl group having 3 to 7 carbon atoms, which may have a branch. For example, examples of the alkyl group having 1 to 8 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, and a sec-butyl group. Examples of the alkoxyalkyl group having 3 to 7 carbon atoms include a group in which one hydrogen atom has been removed from a straight-chain or branched-chain ether, such as methyl ethyl ether, diethyl ether, methyl propyl ether, methyl isopropyl ether, ethyl propyl ether, ethyl isopropyl ether, methyl butyl ether, ethyl butyl ether, methyl sec-butyl ether, ethyl sec-butyl ether, methyl tert-butyl ether, or ethyl tert-butyl ether. Each of (OR ₄ ) may be the same or different.

Examples of silane coupling agents represented by the above general formula (II) include, for example, 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane when n = 1. When n = 2, examples include 3-glycidoxypropylmethyldimethoxysilane and 3-glycidoxypropylmethyldiethoxysilane. When n = 3, examples include 3-glycidoxypropyldimethylmethoxysilane, 3-glycidoxypropyldimethylethoxysilane, 2-(3,4-epoxycyclohexyl)dimethylmethoxysilane, and 2-(3,4-epoxycyclohexyl)dimethylethoxysilane.

In particular, the crosslink density of the cured film of the barrier coating layer using 3-glycidoxypropylmethyldimethoxysilane and 3-glycidoxypropylmethyldiethoxysilane is lower than the crosslink density of a system using trialkoxysilane. Therefore, while the film has excellent gas barrier properties and hot water treatment resistance, it also becomes a flexible cured film and has excellent bending resistance, so that the gas barrier properties of packaging materials using this barrier film are less likely to deteriorate even after the Gelbo flex test.

Silane coupling agents with n=1, 2, or 3 can also be used in combination, and the ratio of the amounts and the amount of silane coupling agent used are determined by the design of the cured film of the barrier coating layer.

The hydroxyl-containing water-soluble resin is capable of dehydration co-condensation with the metal alkoxide, and the degree of saponification is preferably 90% or more and 100% or less, more preferably 95% or more and 100% or less, and even more preferably 99% or more and 100% or less. If the degree of saponification is smaller than the above range, the hardness of the barrier coating layer is likely to decrease.

Specific examples of hydroxyl-containing water-soluble resins include polyvinyl alcohol resins, ethylene-vinyl alcohol copolymers, and polymers of bifunctional phenolic compounds and bifunctional epoxy compounds. Each of these may be used alone, or two or more of them may be mixed or copolymerized. Among these, polyvinyl alcohol is particularly preferred because of its excellent flexibility and affinity, and polyvinyl alcohol resins are preferred.

Specifically, for example, a polyvinyl alcohol resin obtained by saponifying polyvinyl acetate, or an ethylene-vinyl alcohol copolymer obtained by saponifying a copolymer of ethylene and vinyl acetate can be used.
Examples of such polyvinyl alcohol resins include PVA-124 (saponification degree = 99%, polymerization degree = 2,400) manufactured by Kuraray Co., Ltd. and GOHSENOL NM-14 (saponification degree = 99%, polymerization degree = 1,400) manufactured by Nippon Synthetic Chemical Industry Co., Ltd.

(Preferable Structure of Barrier Laminate Film)
Next, a preferred configuration of the barrier laminate film 5 in the thickness direction when the vapor-deposited layer 2 is a transparent vapor-deposited layer containing aluminum oxide will be described with reference to Fig. 10. Fig. 10 shows the results of measuring ions derived from the vapor-deposited layer 2 containing aluminum oxide and ions derived from the substrate 1 using time-of-flight secondary ion mass spectrometry (TOF-SIMS) while repeatedly soft-etching the surface of the barrier laminate film 5 on the side of the gas barrier coating film 3 at a constant rate with a Cs (cesium) ion gun. The vapor-deposited layer 2 of the barrier laminate film 5 includes a transition region identified by the graph analysis diagram shown in Fig. 10.

The transition region is a region between the peak position T2 of the element bond _Al2O4H transformed into aluminum hydroxide, detected by etching the barrier laminate film ₅ from the gas barrier coating film ₃ side using TOF-SIMS, and the interface _T1 between the vapor-deposited layer 2 and the substrate 1. The interface _T1 between the vapor-deposited layer 2 and the substrate 1 is specified as the position where the graph intensity of the element _C6 is half the intensity of the element _C6 in the substrate 1. In Fig. 10, the symbol _W1 represents the thickness of the transition region.

The ratio of the thickness W ₁ of the transition region to the thickness of the deposition layer 2 (hereinafter, also referred to as the transformation rate of the transition region) is desirably 5% or more and 60% or less. By setting the transformation rate to 5% or more and 60% or less, it is possible to suppress the degradation of the barrier property of the barrier laminate film 5 against water vapor when a sterilization treatment such as boiling treatment or retort treatment is performed on a packaging material including the barrier laminate film 5. The retort treatment is a treatment in which a packaging bag made of a packaging material including the barrier laminate film 5 is filled with contents, the packaging bag is sealed, and then the packaging bag is heated under pressure. The temperature of the retort treatment is, for example, 120° C. or more. The boiling treatment is a treatment in which a packaging bag is filled with contents, the packaging bag is sealed, and then the packaging bag is heated in a hot water bath under atmospheric pressure. The temperature of the boiling treatment is, for example, 90° C. or more and 100° C. or less. In addition, a packaging material including a barrier laminate film 5 having a transformation rate in the transition region of 5% or more and 60% or less can effectively function in maintaining barrier properties against gases such as oxygen and water vapor even when used in packaging bags for applications in which sterilization treatments such as boiling treatment or retort treatment are not performed.

The interface between the substrate 1 and the deposition layer 2 is subjected to mechanical and chemical stress due to heat. Therefore, in order to prevent a decrease in adhesion and barrier properties, it is important to firmly coat the substrate 1 with the deposition layer 2 at the interface between the substrate 1 and the deposition layer 2.

Due to its chemical structure, aluminum hydroxide adheres well to plastic films such as polyester film, and because it forms a dense network of its own, it has high water vapor barrier properties. However, the bond structure based on hydrogen bonds between the aluminum hydroxide and the plastic film is prone to microscopic collapse due to thermal stress. In addition, water molecules easily penetrate into the film due to the affinity between the grain boundaries of aluminum hydroxide and the aluminum hydroxide network.

In this embodiment, in order to narrow as much as possible the transition region formed by aluminum hydroxide in the vapor-deposited layer 2 containing aluminum oxide at the interface with the substrate 1, attention is focused on the elemental bond _Al2O4H and the amount of _Al2O4H present is controlled. This is intended to suppress aluminum hydroxide generated from the elemental bond _Al2O4H due to thermal stress and increase the ratio of the aluminum oxide layer containing relatively _less aluminum hydroxide, thereby suppressing microscopic destruction of the vapor-deposited layer 2 caused by water molecules due to thermal stress and destruction of the interface with the plastic film. This makes it possible to provide a barrier laminate film 5 having unprecedented adhesion and barrier properties.

The deposition layer 2 containing aluminum oxide can be formed by depositing the deposition layer 2 on the surface of the substrate 1 that has been pretreated with oxygen plasma. As the deposition method for depositing the deposition layer 2, various deposition methods can be applied from among physical deposition and chemical deposition. As the physical deposition method, a method can be selected from the group consisting of deposition, sputtering, ion plating, ion beam assisted deposition, and cluster ion beam deposition, and as the chemical deposition method, a method can be selected from the group consisting of plasma CVD, plasma polymerization, thermal CVD, and catalytic reaction CVD. In this embodiment, the deposition method of physical deposition is preferred.

A specific example of a method for obtaining the graph in Figure 10 will be described. First, etching is performed from the outermost surface of the gas barrier coating film 3 using Cs, and analysis is performed on the elemental bonds at the interfaces between the gas barrier coating film 3, the deposition layer 2, and a film such as the substrate 1, and on the elemental bonds in the deposition layer 2. This makes it possible to obtain the graph shown in Figure 10.

Next, a specific example of a method for analyzing the graph in FIG. 10 will be described. Here, we will explain the case where the gas barrier coating film 3 contains silicon oxide.

First, in the graph, the position where the intensity of _SiO2 (mass number 59.96), a constituent element of gas barrier coating film 3, is half that of gas barrier coating film 3 is identified as the interface between gas barrier coating film 3 and vapor-deposited layer 2. Next, the position where the intensity of _C6 (mass number 72.00), a constituent material of substrate 1, is half that of substrate 1 is identified as the interface between substrate 1 and vapor-deposited layer 2. The distance in the thickness direction between the two interfaces is used as the thickness of vapor-deposited layer 2.

Next, the peak of the measured element _{bond Al2O4H} (mass number 118.93) is obtained, and the region from the peak to the interface is defined as the transition region. However, if the gas barrier coating film 3 is composed of a material with the same mass number as _Al2O4H (mass number _118.93 ), it is necessary to separate the waveform of 118.93.

When reaction products _AlSiO4 and _{hydroxide Al2O4H} are generated at the interface between the gas barrier coating film 3 and the vapor deposition layer 2, they can be separated from the _Al2O4H present at the interface between the substrate 1 and the vapor deposition layer _2. In this way, the separation of the corrugations can be dealt with appropriately depending on the material of the gas barrier coating film 3.

In waveform separation, for example, the profile of mass number 118.93 obtained by TOF-SIMS can be nonlinearly curve-fitted using a Gaussian function, and overlapping peaks can be separated using the least-squares Levenberg Marquardt algorithm.

The above analysis assumes that the barrier laminate film 5 includes the substrate 1, the deposition layer 2, and the gas barrier coating film 3, but the same analysis can be applied to the case where the barrier laminate film 5 includes the substrate 1 and the deposition layer 2 but does not include the gas barrier coating film 3. Even if the barrier laminate film 5 does not include the gas barrier coating film 3, by setting the conversion rate of the transition region of the deposition layer 2 within a predetermined range, it is possible to suppress the barrier properties of the barrier laminate film 5 against water vapor from decreasing when a packaging material including the barrier laminate film 5 is subjected to a sterilization treatment such as boiling or retort treatment. When the barrier laminate film 5 includes the substrate 1 and the deposition layer 2 and etching is performed from the deposition layer 2 side using time-of-flight secondary ion mass spectrometry (TOF-SIMS), it is preferable that the conversion rate of the transition region of the deposition layer 2 is 45% or less.

<Method of producing barrier laminate film>
Next, an example of a method for producing the barrier laminate film 5 will be described.

First, a substrate 1 is prepared. Next, a deposition layer 2 containing aluminum oxide is formed on the surface of the substrate 1. FIG. 11 is a diagram showing an example of a deposition device 60. The deposition device 60 and a deposition method using the deposition device 60 are described below.

As shown in FIG. 11, in the film forming apparatus 60, partition walls 85a to 85c are formed in the decompression chamber 62. The partition walls 85a to 85c form the substrate transport chamber 62A, the plasma pretreatment chamber 62B, and the film forming chamber 62C. In particular, the plasma pretreatment chamber 62B and the film forming chamber 62C are formed as spaces surrounded by the partition walls and the partition walls 85a to 85c, and each chamber further has an exhaust chamber formed inside as necessary.

The plasma pretreatment chamber 62B and the plasma pretreatment process in the plasma pretreatment chamber 62B will be described. In the plasma pretreatment chamber 62B, a plasma pretreatment roller 70 that transports the substrate 1 to be pretreated and enables plasma treatment is provided so that a portion of the roller 70 is exposed to the substrate transport chamber 62A. The substrate 1 is moved to the plasma pretreatment chamber 62B while being wound up.

The plasma pretreatment chamber 62B and the deposition chamber 62C are provided adjacent to the substrate transport chamber 62A, and the substrate 1 can be moved without being exposed to the atmosphere. The pretreatment chamber 62B and the substrate transport chamber 62A are connected by a rectangular hole, through which a part of the plasma pretreatment roller 70 protrudes to the substrate transport chamber 62A side, and a gap is opened between the wall of the transport chamber and the pretreatment roller 70, and the substrate 1 can be moved from the substrate transport chamber 62A to the deposition chamber 62C through the gap. The same structure is also formed between the substrate transport chamber 62A and the deposition chamber 62C, and the substrate 1 can be moved without being exposed to the atmosphere.

The substrate transport chamber 62A is provided with a winding roller as a winding means for winding up the substrate 1 with the deposition layer 2 formed on one side, which has been moved again to the substrate transport chamber 12A by the deposition roller 75, into a roll, so that the substrate 1 with the deposition layer 2 formed thereon can be wound up.

When manufacturing a barrier laminate film 5 having a vapor deposition layer 2 containing aluminum oxide, the plasma pretreatment chamber 62B is configured to separate the space in which plasma is generated from other areas and to efficiently evacuate the opposing space, making it easier to control the plasma gas concentration and improving productivity. The pretreatment pressure formed by reducing the pressure can be set and maintained at approximately 0.1 Pa to 100 Pa, and in particular, the treatment pressure for oxygen plasma pretreatment is preferably 1 to 20 Pa to achieve a preferred conversion rate in the transition region of the vapor deposition layer 2 containing aluminum oxide.

The transport speed of the substrate 1 is not particularly limited, but from the viewpoint of production efficiency, it can be at least 200 to 1000 m/min. In particular, the transport speed for oxygen plasma pretreatment is preferably 300 to 800 m/min to obtain the transformation rate of the transition region of the deposition layer 2 containing aluminum oxide.

The plasma pretreatment roller 70 that constitutes the plasma pretreatment device is intended to prevent the substrate 1 from shrinking or being damaged by heat during plasma treatment by the plasma pretreatment means, and to apply oxygen plasma P uniformly and widely to the substrate 1. It is preferable that the pretreatment roller 70 can be adjusted to a constant temperature between -20°C and 100°C by adjusting the temperature of the temperature control medium circulating inside the pretreatment roller.

The plasma pretreatment means includes a plasma supply means and a magnetic forming means. The plasma pretreatment means cooperates with the plasma pretreatment roller 70 to confine the oxygen plasma P near the surface of the substrate 1.

The plasma pretreatment means is provided so as to cover a portion of the pretreatment roller 70. Specifically, the plasma supply means 72 and the magnetic field forming means 73 constituting the plasma pretreatment means are arranged along the surface near the outer periphery of the pretreatment roller 70. The plasma supply means 72 includes a plasma supply nozzle that supplies plasma raw material gas. The magnetic field forming means 73 has a magnet or the like to promote the generation of plasma P. The plasma pretreatment means also has an electrode 71 to which a voltage is applied between the pretreatment roller 70. Note that, in FIG. 11, an example is shown in which the electrode 71 and the plasma supply means 72 are separate members, but this is not limiting. Although not shown, the electrode 71 and the plasma supply means 72 may be configured as an integrated member.

By generating plasma P in the space between the pretreatment roller 70 and the magnetic forming means 73 and forming an area of high plasma density near the surface of the pretreatment roller 70 and the substrate 1, oxygen plasma pretreatment can be performed on the inner surface of the substrate 1 to form a plasma-treated surface.

The plasma supply means 72 of the plasma pretreatment means includes a raw material gas volatilization supply device 68 connected to a plasma supply nozzle provided outside the decompression chamber 62, and a raw material gas supply line that supplies raw material gas from the device. The plasma raw material gas supplied is oxygen alone or a mixed gas of oxygen gas and an inert gas, which is supplied from a gas storage section through a flow controller while the gas flow rate is measured. The inert gas may be one or a mixed gas of two or more types selected from the group consisting of argon, helium, and nitrogen.

These supplied gases are mixed in a predetermined ratio as necessary to form a plasma raw material gas alone or a mixed gas for plasma formation, which is then supplied to the plasma supply means. The single or mixed gas is supplied to the plasma supply nozzle of the plasma supply means, and supplied near the outer periphery of the pretreatment roller 70 where the supply port of the plasma supply nozzle opens. The nozzle opening is directed toward the substrate 1 on the pretreatment roller 70, and is arranged and configured so that oxygen plasma P can be diffused and supplied uniformly over the entire surface of the substrate 1. This allows uniform plasma pretreatment to be performed on a large area of the substrate 1.

In order to make the transformation rate of the transition region of the deposition layer 2 containing aluminum oxide 5% or more and 60% or less as described above, the mixture ratio of oxygen gas and the inert gas (oxygen gas/inert gas) in the oxygen plasma pretreatment is preferably 6/1 to 1/1, more preferably 5/2 to 3/2. By making the mixture ratio 6/1 to 1/1, the film formation energy of the deposition layer 2 on the substrate 1 increases, and by making it 5/2 to 3/2, aluminum hydroxide is formed near the interface of the substrate 1, i.e., the transformation rate of the transition region decreases.

The electrode 71 functions as an opposing electrode for the pretreatment roller 70. The plasma raw material gas supplied is excited by the potential difference caused by the high-frequency voltage, low-frequency voltage, etc. supplied between the electrode 71 and the pretreatment roller 70, and plasma P is generated and supplied.

Specifically, the electrode 71 is a plasma pretreatment roller that is installed as a plasma power source, and an AC voltage with a frequency of 10 Hz to 2.5 GHz is applied between the opposing electrode, and input power control or impedance control can be performed to apply any voltage between the plasma pretreatment roller 70. The film forming device 60 is equipped with a power source 82 that can apply a bias voltage that makes the oxygen plasma P, which can perform a process to physically or chemically modify the surface properties of the substrate 1, a positive potential.

The plasma intensity per unit area is preferably 50 to 8000 W·sec/ ^m2 . Below 50 W·sec/m2, the effect of the plasma pretreatment is not observed, and above 8000 W·sec/ ^m2 , the substrate 1 tends to be deteriorated by the plasma, such as worn out, damaged, discolored, and burned. In ^particular , the plasma intensity per unit area is preferably 100 to 1000 W·sec/ ^m2 . By applying the above-mentioned plasma intensity with a bias voltage perpendicular to the substrate 1, the adhesion with the deposition layer 2 containing aluminum oxide can be stably improved.

The magnetic forming means 73 may be one in which an insulating spacer and a base plate are provided inside a magnet case, and a magnet is provided on this base plate. An insulating shield plate may be provided on the magnet case, and an electrode may be attached to this insulating shield plate. The magnet case and the electrode are electrically insulated, and even if the magnet case is installed and fixed inside the reduced pressure chamber 62, the electrode can be at an electrically floating level. By providing a magnet, reactivity near the surface of the substrate 1 is increased, making it possible to form a good plasma pre-treated surface at high speed.

Preferably, the magnet is configured so that the magnetic flux density at the surface of the substrate 1 is between 10 gauss and 10,000 gauss. If the magnetic flux density at the surface of the substrate 1 is 10 gauss or more, it is possible to sufficiently increase the reactivity near the surface of the substrate 1, and a good pre-treated surface can be formed at high speed.

Next, the deposition chamber 62C and the deposition process in the deposition chamber 62C will be described. The deposition device 60 has a deposition roller 75 arranged in the reduced pressure deposition chamber 62C, and a target of the deposition film forming means 74 arranged opposite the deposition roller 75. The deposition roller 75 wraps around and transports the substrate 1 with the treated surface of the substrate 1, which has been pretreated in the plasma pretreatment device, facing outward. In the deposition process, the target of the deposition film forming means 74 is evaporated to form an aluminum oxide film on the surface of the substrate 1.

The deposition film forming means 74 is, for example, a resistance heating type, and uses an aluminum metal wire as an evaporation source, and supplies oxygen to oxidize the aluminum vapor, forming a deposition layer 2 containing aluminum oxide on the surface of the substrate 1.

The thickness of the deposited layer 2 containing aluminum oxide formed as described above is preferably 3 to 50 nm, and more preferably 9 to 30 nm. Within this range, the barrier properties can be maintained. However, if the deposited layer 2 containing aluminum oxide is very thin, it becomes difficult to calculate the transformation rate of the transition region using TOF-SIMS measurement.

Next, a method for forming the gas barrier coating film 3 on the deposition layer 2 will be described. First, the above-mentioned metal alkoxide, silane coupling agent, hydroxyl group-containing water-soluble resin, reaction accelerator (sol-gel catalyst, acid, etc.), and organic solvent such as water as a solvent, methyl alcohol, ethyl alcohol, isopropanol, etc., are mixed to prepare a coating agent for the gas barrier coating film made of a resin composition.

When the gas barrier coating film 3 contains a silane coupling agent, the coating agent for the gas barrier coating film may be prepared as follows. First, a metal alkoxide such as an alkoxysilane is mixed with a silane coupling agent. The metal alkoxide and the silane coupling agent are preferably mixed at 10°C or less. This makes it easier for the film structure in the gas barrier coating film 3 to be formed to be dense. Next, the mixture of the metal alkoxide and the silane coupling agent is mixed with a hydroxyl group-containing water-soluble resin such as a polyvinyl alcohol resin.

After preparing the coating agent for the gas barrier coating film, the coating agent for the gas barrier coating film is applied to the deposition layer 2 by a conventional method and dried. This drying step causes the condensation or co-condensation reaction to proceed further, forming a coating film. The above coating operation may be further repeated on the first coating film to form multiple coating films consisting of two or more layers.

Furthermore, the substrate is heat-treated for 3 seconds to 10 minutes at a temperature in the range of 20 to 200°C, preferably 50 to 180°C, and at a temperature below the softening point of the resin constituting the substrate 1. This makes it possible to form a gas barrier coating film 3 made of the coating agent for gas barrier coating film on the deposition layer 2. In this way, a barrier laminate film 5 having the substrate 1, deposition layer 2, and gas barrier coating film 3 can be produced.

<Packaging materials>
Next, the packaging material 8 for forming the packaging bag will be described. The packaging material 8 includes the above-mentioned barrier laminate film 5 and a thermoplastic resin layer 7 laminated on the barrier laminate film 5. In the example shown in Fig. 12, the thermoplastic resin layer 7 is laminated on the surface of the barrier laminate film 5 facing the deposition layer 2 via an adhesive layer 6. The thermoplastic resin layer 7 forms the inner surface of the packaging material 8 (the inner surface of the packaging bag formed by the packaging material 8). Although not shown, a printed layer may be provided between the barrier laminate film 5 and the adhesive layer 6.

(Thermoplastic resin layer)
The thermoplastic resin layer 7 may be any resin layer or film that can be melted by heat and fused to each other. For example, it is preferable to use a resin or film made of one or more of low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, polypropylene, polymethylpentene, polystyrene, ethylene-vinyl acetate copolymer, α-olefin copolymer, ionomer resin, ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-propylene copolymer, elastomer, etc., and among these, since it is the layer that comes into contact with the contents such as food, it is more preferable to use a resin or film made of one or more olefin-based resins such as polyethylene and polypropylene, which have excellent hygiene, heat resistance, chemical resistance, and aroma retention.
The thickness is preferably 3 μm or more and 100 μm or less, and more preferably 15 μm or more and 70 μm or less.
The thermoplastic resin layer 7 is preferably made of an unstretched film. The term "unstretched" is a concept including not only a film that is not stretched at all, but also a film that is slightly stretched due to tension applied during film formation.

The packaging bag made of the packaging material 8 may be subjected to sterilization treatment such as boiling or retort treatment at high temperatures. Preferably, the thermoplastic resin layer 7 has heat resistance that can withstand these high-temperature treatments.

(Other Aspects)
Another aspect of the present invention is a barrier laminate film comprising a substrate and a vapor deposition layer containing a metal or an inorganic compound and provided on the substrate, the substrate containing polyester as a main component, and a value obtained by dividing the tensile strength of the substrate by its tensile elongation in at least one direction is 2.0 MPa/% or more.

In another aspect of the barrier laminate film of the present invention, the puncture strength of the substrate may be 9.5 N or more.

In another embodiment of the barrier laminate film of the present invention, the substrate may have a loop stiffness of 0.0017 N or more in the machine direction and perpendicular direction, and may contain polyester as a main component.

In another aspect of the barrier laminate film of the present invention, the substrate may contain polybutylene terephthalate as a main component.

In another aspect of the present invention, the barrier laminate film may further include a gas barrier coating film provided on the deposition layer.

In another aspect of the barrier laminate film of the present invention, the vapor deposition layer may be a transparent vapor deposition layer containing an inorganic compound.

In another aspect of the barrier laminate film of the present invention, the vapor deposition layer is a transparent vapor deposition layer containing aluminum oxide, and the transparent vapor deposition layer includes a transition region, which is a region between the position of the peak of elemental bond Al ₂ O ₄ H detected by etching the vapor deposition film from the transparent vapor deposition layer side using time-of-flight secondary ion mass spectrometry (TOF-SIMS) and the interface between the transparent vapor deposition layer and the first plastic film, and the ratio of the thickness of the transition region to the thickness of the transparent vapor deposition layer may be 5% or more and 60% or less.

Another aspect of the present invention is a method for producing a barrier laminate film, comprising a step of preparing a substrate, and a deposition step of depositing a metal or inorganic compound onto the substrate to form a deposition layer on the substrate, the substrate containing polyester as a main component, and the value of the tensile strength of the substrate divided by the tensile elongation in at least one direction is 2.0 [MPa/%] or more.

The method for producing a barrier laminate film according to another aspect of the present invention may further include a plasma pretreatment step of subjecting the substrate to a plasma treatment to form a plasma-treated surface on the substrate, and the deposition step may form the deposition layer on the plasma-treated surface of the substrate.

In another aspect of the method for producing a barrier laminate film according to the present invention, the deposition step may form the deposition layer on the plasma-treated surface of the substrate by physical deposition.

In another embodiment of the method for producing a barrier laminate film according to the present invention, the plasma pretreatment step includes a step of supplying a mixed gas of oxygen gas and an inert gas as a plasma raw material gas, and the mixture ratio of the oxygen gas and the inert gas (oxygen gas/inert gas) may be within a range of 6/1 to 1/1.

In another embodiment of the method for producing a barrier laminate film according to the present invention, the deposition layer is a transparent deposition layer containing an inorganic compound, and the film production method may further include a step of forming a gas barrier coating film by applying a coating agent for a gas barrier coating film onto the deposition layer and drying by heating.

In another embodiment of the method for producing a barrier laminate film according to the present invention, the gas barrier coating film may be a layer formed by applying a mixed solution of a metal alkoxide and a water-soluble polymer and then drying the mixture by heating.

In another embodiment of the method for producing a barrier laminate film according to the present invention, the gas barrier coating film may be a layer formed by applying a mixed solution of a metal alkoxide, a silane coupling agent, and a water-soluble polymer, and then heating and drying the mixture.

Another aspect of the present invention is a packaging material comprising a substrate, a barrier laminate film having a vapor deposition layer containing a metal or an inorganic compound provided on the substrate, and a thermoplastic resin layer laminated on the barrier laminate film, the substrate containing polyester as a main component, and the tensile strength of the substrate divided by the tensile elongation in at least one direction is 2.0 [MPa/%] or more.

In another aspect of the packaging material of the present invention, it may be used for packaging bags for boiling or for retort sterilization.

Next, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the description of the following examples as long as it does not deviate from the gist of the invention.

[Example A1]
As the substrate 1, a high-stiffness PET film having a loop stiffness of 0.0017 N or more and made of petroleum-derived PET was prepared. Specifically, XP-55 manufactured by Toray Industries, Inc. was used as the high-stiffness PET film. The thickness of the high-stiffness PET film was 16 μm. The measured values of the loop stiffness of the high-stiffness PET film were 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 polyester 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 polyester 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 polyester 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/%], and 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 the perpendicular direction was 0.4%.

Next, the puncture strength of the high stiffness PET film was measured in accordance with JIS Z1707 7.4. The measuring device used was a Tensilon universal material testing machine RTC-1310 manufactured by A&D. Specifically, a test piece of the high stiffness PET film in a fixed state was pierced from the outer surface 30y side with a semicircular needle having a diameter of 1.0 mm and a tip radius of 0.5 mm at a speed of 50 mm/min (50 mm per minute), and the maximum value of the stress until the needle penetrated the high stiffness PET film was measured. The maximum value of the stress was measured for five or more test pieces, and the average value was taken as the puncture strength of the high stiffness PET film. The environment during the measurement was a temperature of 23°C and a relative humidity of 50%. As a result, the puncture strength was 10.2 N.

[Example A2]
As the substrate 1, a PBT film including a plurality of layers and produced by a casting method, as described in the first configuration above, was prepared. The content of PBT in each layer was 80%, the number of layers was 1024, and the thickness of the PBT film was 15 μm. The tensile strength of the PBT film in the flow direction was 191 MPa, and the tensile strength of the PBT film in the perpendicular direction was 289 MPa. The tensile elongation of the PBT film in the flow direction was 195%, and the tensile elongation of the PBT film in the perpendicular direction was 100%. In this case, the value obtained by dividing the tensile strength of the PBT film in the flow direction by the tensile elongation was 0.98 [MPa/%], and the value obtained by dividing the tensile strength of the PBT film in the perpendicular direction by the tensile elongation was 2.89 [MPa/%].
The thermal shrinkage of the PBT film in both the machine direction and the perpendicular direction was 0.4%.

[Example B1]
An example in which a vapor-deposited layer 2 is formed on a substrate 1, and a gas-barrier coating film 3 is formed on the vapor-deposited layer 2 to produce a barrier laminate film 5 will be described.

First, a roll of the 16 μm-thick high-stiffness PET film used in Example A1 above was prepared as the substrate 1. Next, using the above-mentioned film-forming device 60 shown in FIG. 11, the substrate 1 was subjected to oxygen plasma treatment, and then a vapor-deposited layer 2 containing aluminum oxide and having a thickness of 12 nm was formed on the oxygen plasma-treated surface. The oxygen plasma treatment and film-forming process will be described in detail below.

In the oxygen plasma treatment, plasma was introduced from the plasma supply nozzle 72 under the following conditions in the plasma pretreatment chamber 62B onto the surface of the substrate 1 on which the deposition layer 2 was to be formed, and the substrate 1 transported at a transport speed of 400 m/min was subjected to plasma pretreatment. As a result, an oxygen plasma-treated surface was formed on the surface of the substrate 1 on which the deposition layer 2 was to be formed.
[Oxygen plasma pretreatment conditions]
Plasma intensity: 200 W·sec/ ^m2
Plasma formation gas ratio: oxygen/argon = 2/1
Voltage applied between pretreatment drum and plasma supply nozzle: 340 V
Vacuum level in pre-treatment section: 3.8 Pa

In the film formation process, in the film formation chamber 62C into which the substrate 1 continuously transported from the plasma pretreatment chamber 62B was carried in, a deposition layer 2 containing aluminum oxide and having a thickness of 12 nm was formed on the substrate 1 by vacuum deposition using aluminum as a target on the oxygen plasma treated surface of the substrate 1. A reactive resistance heating method was adopted as the heating means for the vacuum deposition method. The film formation conditions were as follows.
[Aluminum oxide film formation conditions]
・Vacuum degree: 8.1×10 ^-2 Pa
Conveying speed: 400 m/min
Oxygen gas supply amount: 20,000 sccm

Subsequently, a gas barrier coating film 3 was formed on the vapor deposition layer 2. Specifically, first, 385 g of water, 67 g of isopropyl alcohol, and 9.1 g of 0.5 N hydrochloric acid were mixed and the pH of the solution was adjusted to 2.2, and 175 g of tetraethoxysilane as a metal alkoxide and 9.2 g of glycidoxypropyltrimethoxysilane as a silane coupling agent were mixed into the solution while cooling to 10° C. to prepare solution A.
Solution B was prepared by mixing 14.7 g of polyvinyl alcohol having a polymerization degree of 2,400 and a saponification degree of 99% or more as a water-soluble polymer, 324 g of water, and 17 g of isopropyl alcohol.
Subsequently, the liquid A and the liquid B were mixed in a weight ratio of 6.5:3.5. The solution thus obtained was used as a coating agent for a gas barrier coating film.

The gas barrier coating film coating agent prepared above was coated on the deposition layer 2 by spin coating. After that, the deposition layer 2 was heated in an oven at 180°C for 60 seconds to form a gas barrier coating film 3 having a thickness of about 400 nm on the deposition layer 2. In this way, a barrier laminate film 5 having the substrate 1, the deposition layer 2, and the gas barrier coating film 3 was obtained.

The transformation rate, oxygen permeability, water vapor permeability, and loop stiffness of the barrier laminate film 5 of Example B1 were measured.

(Metamorphism rate)
In a vacuum environment, the surface of the gas barrier coating film 3 of the barrier laminate film 5 was repeatedly soft-etched at a constant rate with a Cs (cesium) ion gun while measuring the ions derived from the gas barrier coating film 3, the vapor-deposited layer 2, and the ions derived from the substrate 1 using time-of-flight secondary ion mass spectrometry (TOF-SIMS). For example, mass analysis was performed on C ₆ (mass number 72.00) ions derived from the resin film of the substrate 1 and Al ₂ O ₄ H (mass number 118.93) ions derived from the aluminum oxide vapor-deposited film of the vapor-deposited layer 2.

The time-of-flight secondary ion mass spectrometer used in the TOF-SIMS was a TOF.SIMS5 manufactured by ION TOF, Inc., and measurements were performed under the following measurement conditions, thereby obtaining the graph shown in FIG.
(TOFSIMS measurement conditions)
Primary ion type: _Bi3 ++ (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
Etching rate: 3 sec/cycle
Evacuation time: 15 hours or more at 1×10 ⁻⁶ mbar or less. Measurements using a time-of-flight secondary ion mass spectrometer were carried out within 30 hours after the start of evacuation.

In the graph, the position where the strength of _SiO2 (mass number 59.96), a constituent element of gas barrier coating film 3, is half that of gas barrier coating film 3, was identified as the interface between gas barrier coating film 3 and vapor-deposited layer 2. Also, the position where the strength of _C6 (mass number 72.00), a constituent material of substrate 1, is half that of substrate 1, was identified as the interface between substrate 1 and vapor-deposited layer 2. Also, the distance in the thickness direction between the two interfaces was adopted as the thickness of vapor-deposited layer 2.

Next, the peak representing the measured element _{bond Al2O4H (} mass number 118.93) was obtained, and the region from the peak to the interface was defined as the transition region. However, if the gas barrier coating film _{3 is composed of a material with the same mass number as Al2O4H (} mass number 118.93), it is necessary to separate the waveform of 118.93.

When reaction products _AlSiO4 and _{hydroxide Al2O4H} are generated at the interface between the gas barrier coating film 3 and the vapor deposition layer 2, they can be separated from the _Al2O4H present at the interface between the substrate 1 and the vapor deposition layer _2. In this way, the separation of the corrugations can be dealt with appropriately depending on the material of the gas barrier coating film 3.

In waveform separation, for example, the profile of mass number 118.93 obtained by TOF-SIMS may be subjected to nonlinear curve fitting using a Gaussian function, and overlapping peaks may be separated using the least squares Levenberg Marquardt algorithm.

Two samples were prepared from the barrier laminate film 5 of Example B1, and the conversion rate of the vapor-deposited layer 2 for each of the two samples was calculated as (thickness _W1 of the transition region/thickness of the vapor-deposited layer 2) × 100 (%). As a result, the conversion rate of the first sample was 36.2%, and the conversion rate of the second sample was 28.8%.

(Loop Stiffness)
The above-mentioned rectangular test piece 40 was prepared from the barrier laminate film 5 of Example B1, and the loop stiffness in the machine direction and the perpendicular direction was measured. The measuring device used was a loop stiffness tester (registered trademark) LOOP STIFFNESS TESTER DA type No. 581 manufactured by Toyo Seiki Seisakusho. The environment during the measurement was a temperature of 23°C and a relative humidity of 50%. As a result, the loop stiffness in the machine direction of the barrier laminate film 5 was 0.0021 N, and the loop stiffness in the perpendicular direction was 0.0.0021 N.

(Oxygen permeability)
The barrier laminate film 5 prepared as described above and a 60 μm-thick unstretched polypropylene film (CPP film) were bonded together by a dry lamination method using a two-component curing polyurethane adhesive to prepare a packaging material 8. As the CPP film, an unstretched polypropylene film ZK207 manufactured by Toray Advanced Film Co., Ltd. was used.

Next, packaging material 8 was aged for 48 hours, and then a sample was made from packaging material 8 to evaluate the oxygen permeability before retort treatment.

Also, a B5 size four-sided sealed pouch was produced using the packaging material 8. Then, 100 mL of water was poured into the four-sided sealed pouch from the top opening, and then a seal was formed at the top to seal the four-sided sealed pouch. Then, the four-sided sealed pouch was subjected to a retort treatment at 121° C. for 40 minutes.
Next, the packaging material 8 constituting one side of the four-side sealed pouch after the retort treatment was cut out to prepare a sample for evaluating the oxygen transmission rate after the retort treatment.

Next, the sample before retort treatment and the sample after retort treatment were set so that the substrate 1 was on the oxygen supply side, and the oxygen permeability was measured in accordance with JIS K 7126 B method under the measurement conditions of 23°C and 100% RH atmosphere. As a measuring instrument, an oxygen permeability measuring device (manufactured by Modern Control (MOCON) [model name: OX-TRAN 2/21]) was used. As a result, the oxygen permeability of the sample before retort treatment was 0.24cc/m ² /24hr/atm. Moreover, the oxygen permeability of the sample after retort treatment was 0.20cc/m ² /24hr/atm. Thus, in both the state before retort treatment and the state after retort treatment, the oxygen permeability could be made less than 0.50cc/m ² /24hr/atm.

(Water vapor permeability)
The water vapor permeability was measured using the same sample as in the case of measuring the oxygen permeability. Specifically, each sample was set so that the substrate 1 was on the sensor side, and the water vapor permeability was measured in accordance with JIS K 7126 B method under the measurement conditions of 37.8°C and 100% RH atmosphere. As a measuring instrument, a water vapor permeability measuring device (a measuring instrument manufactured by MOCON [model name: PERMATRAN 3/33]) was used. As a result, the water vapor permeability of the sample before retort treatment was 0.61 g/m ² /24hr. In addition, the water vapor permeability of the sample after retort treatment was 1.05 g/m ² /24hr. In this way, the water vapor permeability could be made less than 1.5 g/m ² /24hr in both the state before retort treatment and the state after retort treatment.

[Example B2]
A barrier laminate film 5 including a substrate 1 and a deposition layer 2 provided on the substrate 1 was produced in the same manner as in Example B1, except that the gas barrier coating film 3 was not formed on the deposition layer 2. Then, two samples were prepared from the barrier laminate film 5 of Example B2 in the same manner as in Example B1, and the conversion rate of the deposition layer 2 for each of the two samples was calculated as (thickness W ₁ of the transition region/thickness of the deposition layer 2)×100(%). As a result, the conversion rate in the second sample was 37.8%, and the conversion rate in the second sample was 42.2%.

The above-mentioned rectangular test piece 40 was also prepared from the barrier laminate film 5 of Example B2, and the loop stiffness in the machine direction and the vertical direction was measured in the same manner as in Example B1. As a result, the loop stiffness in the machine direction of the barrier laminate film 5 was 0.0021 N, and the loop stiffness in the vertical direction was 0.0021 N.

[Comparative Example B1]
A barrier laminate film 5 including a substrate 1, a deposition layer 2 provided on the substrate 1, and a gas barrier coating film 3 provided on the deposition layer 2 was produced in the same manner as in Example B1, except that a biaxially stretched PET film having a loop stiffness of less than 0.0017 N in both the machine direction and the perpendicular direction and made of petroleum-derived PET was used as the substrate 1. Then, in the same manner as in Example B1, the above-mentioned rectangular test piece 40 was produced from the barrier laminate film 5 of Comparative Example B1, and the loop stiffness in the machine direction and perpendicular direction was measured. As a result, the loop stiffness in the machine direction of the barrier laminate film 5 was 0.0014 N, and the loop stiffness in the perpendicular direction was 0.0016 N.

Reference Signs List 1 Substrate 2 Vapor deposition layer 3 Gas barrier coating film 5 Barrier laminate film 6 Adhesive layer 7 Thermoplastic resin layer 8 Packaging material 60 Film forming device 62 Decompression chamber 62A Substrate transport chamber 62B Plasma pretreatment chamber 62C Film forming chamber 63 Unwinding roller 64 Guide roller 65 Winding roller 68 Raw material gas volatilization supply device 69 Raw material gas supply nozzle 70 Plasma pretreatment roller 71 Electrode 72 Plasma supply nozzle 75 Film forming roller 76 Film forming means 80 Vacuum pump 81 Power supply wiring 82 Power sources 85a to 85c Partition wall

Claims (14)

A substrate;
A deposition layer provided on the substrate and containing a metal or an inorganic compound;
The substrate has a loop stiffness of 0.0017 N or more in the machine direction and the perpendicular direction, and contains polyester as a main component;
In at least one direction, the tensile strength of the substrate divided by the tensile elongation is 2.0 [MPa/%] or more;
The thickness of the substrate is 16 μm or more and 25 μm or less. The barrier laminate film according to claim 1, wherein the puncture strength of the substrate is 9.5 N or more. The barrier laminate film according to claim 1 or 2, further comprising a gas barrier coating film provided on the deposition layer. The barrier laminate film according to any one of claims 1 to 3, wherein the vapor deposition layer is a transparent vapor deposition layer containing an inorganic compound. the deposition layer is a transparent deposition layer containing aluminum oxide,
the transparent deposition layer includes a transition region;
the transition region is a region between the position of a peak of elemental bond Al ₂ O ₄ H detected by etching the barrier laminate film from the transparent deposition layer side by using a time-of-flight secondary ion mass spectrometry (TOF-SIMS) and the interface between the transparent deposition layer and the substrate,
4. The barrier laminate film according to claim 1, wherein a ratio of a thickness of the transition region to a thickness of the transparent vapor deposition layer is 5% or more and 60% or less. Providing a substrate;
A deposition step of depositing a metal or an inorganic compound on the substrate to form a deposition layer on the substrate,
The substrate has a loop stiffness of 0.0017 N or more in the machine direction and the perpendicular direction, and contains polyester as a main component;
In at least one direction, the tensile strength of the substrate divided by the tensile elongation is 2.0 [MPa/%] or more;
The method for producing a barrier laminate film, wherein the substrate has a thickness of 16 μm or more and 25 μm or less. The method further includes a plasma pretreatment step of subjecting the substrate to a plasma treatment to form a plasma-treated surface on the substrate,
The method for producing a barrier laminate film according to claim 6 , wherein the vapor deposition step forms the vapor deposition layer on the plasma-treated surface of the substrate. The method for producing a barrier laminate film according to claim 7, wherein the vapor deposition step forms the vapor deposition layer on the plasma-treated surface of the substrate by physical vapor deposition. The plasma pretreatment step includes a step of supplying a mixed gas of oxygen gas and an inert gas as a plasma raw material gas,
The method for producing a barrier laminate film according to claim 7 or 8, wherein a mixing ratio of the oxygen gas to the inert gas (oxygen gas/inert gas) is within a range of 6/1 to 1/1. the vapor deposition layer is a transparent vapor deposition layer containing an inorganic compound,
10. The method for producing a barrier laminate film according to claim 6, further comprising the step of applying a coating agent for a gas barrier coating film onto the deposition layer, and drying the applied coating agent by heating to form a gas barrier coating film. The method for producing a barrier laminate film according to claim 10, wherein the gas barrier coating film is a layer formed by coating a mixed solution of a metal alkoxide and a water-soluble polymer and drying it by heating. The method for producing a barrier laminate film according to claim 10, wherein the gas barrier coating film is a layer formed by coating a mixed solution of a metal alkoxide, a silane coupling agent, and a water-soluble polymer, and then drying the mixture by heating. A barrier laminate film having a substrate and a vapor-deposited layer containing a metal or an inorganic compound provided on the substrate;
a thermoplastic resin layer laminated on the barrier laminate film,
The substrate has a loop stiffness of 0.0017 N or more in the machine direction and the perpendicular direction, and contains polyester as a main component;
In at least one direction, the tensile strength of the substrate divided by the tensile elongation is 2.0 [MPa/%] or more;
The packaging material, wherein the thickness of the substrate is 16 μm or more and 25 μm or less. The packaging material according to claim 13, which is used for packaging bags for boiling or for retort sterilization.