EP4596238A1

EP4596238A1 - Multilayer body and packaging bag

Info

Publication number: EP4596238A1
Application number: EP23879735.1A
Authority: EP
Inventors: Junichi Kaminaga; Hiroyuki Wakabayashi; Yoshiki Koshiyama; Yumiko Kojima; Rika Ishii
Original assignee: Toppan Holdings Inc
Current assignee: Toppan Holdings Inc
Priority date: 2022-10-19
Filing date: 2023-10-13
Publication date: 2025-08-06
Also published as: JP2024144753A; JPWO2024085092A1; JP7848835B2; WO2024085092A1; AU2023363440A1; AU2023363440B2; EP4596238A4; JP7537644B1; CN120035516A

Abstract

A multilayer body having a structure in which at least a paper substrate, an anchor coat layer, an aluminum vapor-deposited layer, and an overcoat layer are laminated in this order, in which in the aluminum vapor-deposited layer, a half-value width of a peak of crystal plane (111) of aluminum in X-ray diffraction measurement is 1.6° or more.

Description

Technical Field

The present disclosure relates to a multilayer body and a packaging bag.

Background Art

In many fields such as foods, beverages, medicines, and chemicals, packaging materials are used according to the respective contents. Packaging materials are required to have properties of preventing permeation of water vapor and the like that cause deterioration of the contents (gas barrier properties). Furthermore, packaging materials are required to have oil resistance in order to prevent the oil contained in the contents from seeping out, depending on the contents.
In recent years, due to growing environmental awareness stemming from issues such as marine plastic waste, there has been a growing momentum to reduce plastics. From the viewpoint of reducing the amount of use of plastic materials, it has been considered to use paper instead of plastic materials in various fields. For example, the following Patent Literature 1 discloses a multilayer body in which a barrier layer is laminated on paper.

Citation List

Patent Literature

Patent Literature 1: Japanese Unexamined Patent Publication No. 2020-69783

Summary of Invention

Technical Problem

Paper has a property of retaining creases (also referred to as dead hold property), and therefore has a feature that it is easily processable. However, according to an investigation of the inventors of the present invention, it was found that there is still room for improvement in that when packaging bags (pillow packaging, three-sided seal packaging, and gusset packaging) having more acute-angled folds are produced, cracks are generated in the barrier layer, and oil resistance is decreased.
Furthermore, from the viewpoint of the Act on the Promotion of Effective Utilization of Resources, it is required to reduce the amount of use of plastic materials even in multilayer bodies.
Thus, it is an object of the present disclosure to provide a multilayer body that uses paper, the multilayer body having sufficient initial oil resistance as well as sufficient oil resistance even after being folded, and a packaging bag including this multilayer body.

Solution to Problem

In order to solve the above-described problems, the present disclosure provides the following multilayer body and packaging bag.

[1] A multilayer body having a structure in which at least a paper substrate, an anchor coat layer, an aluminum vapor-deposited layer, and an overcoat layer are laminated in this order, wherein in the aluminum vapor-deposited layer, a half-value width of a peak of crystal plane (111) of aluminum in X-ray diffraction measurement is 1.6° or greater.
[2] The multilayer body according to the above-described item [1], wherein the anchor coat layer contains a polyolefin having a polar group or a polyvinyl alcohol-based resin.
[3] The multilayer body according to the above-described item [1] or [2], wherein the overcoat layer contains a polyolefin having a polar group.
[4] The multilayer body according to any one of the above-described items [1] to [3], wherein a hardness of the anchor coat layer as measured by a nanoindentation method at a cross-section in a thickness direction of the multilayer body is 0.3 GPa or less.
[5] The multilayer body according to any one of the above-described items [1] to [4], wherein a hardness of the overcoat layer as measured by a nanoindentation method at a cross-section in a thickness direction of the multilayer body is 0.3 GPa or less.
[6] The multilayer body according to any one of the above-described items [1] to [5], wherein a thickness of the aluminum vapor-deposited layer is 20 nm or more and 100 nm or less.
[7] The multilayer body according to any one of the above-described items [1] to [6], wherein in the aluminum vapor-deposited layer, a half-value width of a peak of crystal plane (111) of aluminum in X-ray diffraction measurement is 2.0° or more and 15.0° or less.
[8] The multilayer body according to the above-described item [7], wherein the aluminum vapor-deposited layer is in contact with a resin layer containing an ionomer or a polyvinyl alcohol-based resin having a degree of saponification of 95% or greater.
[9] A packaging bag including the multilayer body according to any one of the above-described items [1] to [8].
[10] The packaging bag according to the above-described item [9], wherein the packaging bag has a folded part.

Advantageous Effects of Invention

According to the present disclosure, a multilayer body that uses paper, which has sufficient initial oil resistance as well as sufficient oil resistance even after being folded, and a packaging bag including this multilayer body can be provided. Since the above-described multilayer body uses paper, the multilayer body has a crease retention property, which is a characteristic of paper, and also contributes to the reduction of the amount of use of plastic materials.

Brief Description of Drawings

[FIG. 1] FIG. 1 is a schematic cross-sectional view illustrating a multilayer body according to an embodiment of the present disclosure.
[FIG. 2] FIG. 2 is a perspective view illustrating a packaging bag according to an embodiment of the present disclosure.

Description of Embodiments

Embodiments of the present disclosure will be described in detail below, with reference to the drawings as necessary. However, the present disclosure is not intended to be limited to the following embodiments.

A multilayer body according to the present embodiment is a multilayer body having a structure in which at least a paper substrate, an anchor coat layer, an aluminum vapor-deposited layer, and an overcoat layer are laminated in this order, in which in the above-described aluminum vapor-deposited layer, the half-value width of the peak of crystal plane (111) of aluminum in X-ray diffraction measurement is 1.6° or more. Here, the above-described half-value width in X-ray diffraction of the aluminum vapor-deposited layer represents the degree of lattice distortion in the crystal structure of aluminum. When the distortion is large, the half-value width becomes large, and when the distortion is small, the half-value width becomes small. Furthermore, smaller distortion means that the crystal structure of aluminum is denser. In the above-described multilayer body, when the above-described half-value width of the aluminum vapor-deposited layer is 1.6° or more, the denseness of the crystal structure of aluminum can be appropriately decreased to obtain a sparse state. As a result, the stress applied to the aluminum vapor-deposited layer when the multilayer body is folded can be distributed throughout the entire layer, suppressing the generation of cracks in the aluminum vapor-deposited layer when the multilayer body is folded, and any cracks generated in the aluminum vapor-deposited layer can be made small. Therefore, according to the above-described multilayer body, sufficient initial oil resistance as well as sufficient oil resistance even after being folded can be obtained. Furthermore, according to the above-described multilayer body, by setting the above-described half-value width of the aluminum vapor-deposited layer to be within the above-described range, sufficient initial water vapor barrier properties as well as sufficient water vapor barrier properties even after being folded can be obtained. Furthermore, according to the above-described multilayer body, when a material having oxygen barrier properties is used in the anchor coat layer, not only sufficient oxygen barrier properties but also sufficient oxygen barrier properties even after being folded can be obtained by setting the above-described half-value width of the aluminum vapor-deposited layer to be within the above-described range. The multilayer body according to the present embodiment is useful as an oil-resistant multilayer body or a gas barrier multilayer body.
Furthermore, conventional gas barrier multilayer bodies have room for improvement from the viewpoint that the water vapor barrier properties deteriorate when the multilayer bodies are stored under high temperature and high humidity conditions. When a gas barrier multilayer body whose water vapor barrier properties had deteriorated after being stored under high temperature and high humidity conditions (in an environment at 40°C and 90%) was observed under a microscope using transmitted light, a large number of tiny bright spots were recognized, and therefore, it is considered that the water vapor barrier properties had deteriorated due to the occurrence of permeation defects in the aluminum vapor-deposited layer. In contrast, since the multilayer body according to the present embodiment includes an aluminum vapor-deposited layer in which the half-value width of the peak of crystal plane (111) of aluminum in X-ray diffraction measurement is 1.6° or more, the occurrence of permeation defects in the aluminum vapor-deposited layer even after being stored under high temperature and high humidity conditions can be suppressed, and deterioration of the water vapor barrier properties can be suppressed. The inventors of the present invention speculate as follows about the reason why such an effect is obtained.
The generation of permeation defects in the aluminum vapor-deposited layer is affected by the pitting corrosion of aluminum due to corrosive ions, and the stretching stress due to dimensional changes accompanied by moisture absorption and desorption of the paper substrate. From the viewpoint of the crystallinity of the aluminum vapor-deposited layer, it can be said that a highly crystalline layer is excellent in terms of the resistance to corrosive ions; however, it is considered that an amorphous layer that easily follows expansion and contraction is excellent in terms of stress resistance. Here, it is believed that the aluminum vapor-deposited layer has a structure in which the surroundings of crystallites are filled with amorphous parts. Furthermore, the broadening of the X-ray diffraction line width of aluminum is due to the diameter of crystallites and the distortion of crystals. A state with a narrow X-ray diffraction line width is considered to indicate a state in which crystallites formed from ideal crystal lattices and amorphous parts are clearly divided. Therefore, it is speculated that when the X-ray diffraction line width is narrow, pitting corrosion in the amorphous parts and destruction between the ideal crystal lattices or crystals and the amorphous parts due to stretching stress are likely to occur. On the other hand, a state with a broad X-ray diffraction line width is considered to indicate a state in which a distorted crystal structure is adopted, and the separation between crystalline parts and amorphous parts is unclear. Therefore, it is speculated that when the X-ray diffraction line width is wide, pitting corrosion and destruction due to stretching stress are suppressed, and permeation defects are less likely to occur. For the above-described reasons, it is considered that when the above-described half-value width in X-ray diffraction of the aluminum vapor-deposited layer is 1.6° or more, even in a case where the multilayer body is stored under high temperature and high humidity conditions, the occurrence of permeation defects in the aluminum vapor-deposited layer can be suppressed, and deterioration of the water vapor barrier properties can be suppressed. Such effects are more notably provided in a case where the above-described half-value width is 2.0° or more.
FIG. 1 is a schematic cross-sectional view illustrating a multilayer body according to an embodiment. The multilayer body 10 according to an embodiment includes a paper substrate 1, an anchor coat layer 2, an aluminum vapor-deposited layer 3, and an overcoat layer 4 in this order.
The thickness of the multilayer body 10 may be 20 to 100 µm, may be 30 to 80 µm, or may be 40 to 60 µm. When the thickness of the multilayer body 10 is within the above-described range, the multilayer body 10 can obtain more satisfactory water vapor barrier properties and oil resistance not only initially but also after being folded.

[Paper substrate]

The paper substrate 1 may be paper containing plant-derived pulp as a main component. Specific examples of the paper substrate 1 include high-quality paper, special high-quality paper, coated paper, art paper, cast coated paper, imitation vellum paper, kraft paper, and glassine paper. The basis weight of the paper substrate 1 may be 20 to 500 g/m² or 30 to 100 g/m².
The paper substrate 1 may be provided with a coating layer at least on the side of the paper substrate 1 in contact with the anchor coat layer 2. When the paper substrate 1 includes a coating layer, the paper substrate 1 may include at least a paper layer and a coating layer. The coating layer may be provided on both surfaces of the paper substrate 1. By providing the coating layer, the coating layer can prevent the anchor coat layer 2 from penetrating into the paper, and can also accomplish the role as a filling that fills the surface unevenness of the paper, allowing the anchor coat layer 2 to be formed uniformly without defects. The coating layer may use, for example, various copolymers such as styrene-butadiene-based, styrene-acrylic, and ethylene-vinyl acetate-based copolymers, a polyvinyl alcohol-based resin, a cellulose-based resin, or paraffin (wax) as binder resins, and may contain clay, kaolin, calcium carbonate, talc, and mica as fillers. The coating layer may be a clay coating layer containing at least clay as a filler.
When the paper substrate 1 includes a coating layer, the thickness of the coating layer may be 1.5 µm or more and 15 µm or less. The thickness of the coating layer may be 1.8 µm or more, may be 3 µm or more, may be 5 µm or more, or may be 6 µm or more. The thickness of the coating layer may be 12 µm or less, or may be 10 µm or less. When the thickness of the coating layer is within the above-described range, the multilayer body 10 can obtain more satisfactory water vapor barrier properties and oil resistance not only initially but also after being folded.
The thickness of the paper substrate 1 may be 20 to 100 µm, may be 30 to 80 µm, or may be 40 to 60 µm. When the thickness of the paper substrate 1 is within the above-described range, the multilayer body 10 can obtain more satisfactory water vapor barrier properties and oil resistance not only initially but also after being folded.
The proportion occupied by the thickness of the coating layer in the thickness of the paper substrate 1 may be 3% to 25%, or may be 5% to 20%. When this proportion is within the above-described range, the multilayer body 10 can obtain more satisfactory water vapor barrier properties and oil resistance not only initially but also after being folded.
The weight of the paper is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, based on the entire multilayer body. When the weight of the paper is 50% by mass or more based on the entire multilayer body, the amount of use of plastic materials can be sufficiently reduced, the entire multilayer body may be said to be made of paper, and the multilayer body has excellent recyclability.

[Anchor coat layer]

The anchor coat layer 2 is provided on the surface of the paper substrate 1 and is provided for improving the adhesiveness between the paper substrate 1 and the aluminum vapor-deposited layer 3 that will be described below, and for improving the gas barrier properties and oil resistance of the multilayer body. The anchor coat layer 2 may contain a polyolefin having a polar group or a polyvinyl alcohol-based resin.
When the anchor coat layer 2 contains a polyolefin having a polar group, the anchor coat layer 2 has excellent flexibility, can suppress cracking of the aluminum vapor-deposited layer 3 that will be described below after bending (after folding), and can also improve the adhesiveness between the anchor coat layer 2 and the aluminum vapor-deposited layer 3. In addition, by containing a polyolefin having a polar group, a dense film can be formed due to the crystallinity of the polyolefin, and water vapor barrier properties and oil resistance are exhibited. Water vapor barrier properties and oil resistance are exhibited due to the crystallinity of the polyolefin, and by having a polar group, close adhesion to the aluminum vapor-deposited layer 3 is exhibited.
The polyolefin having a polar group may have at least one selected from a carboxyl group, a salt of a carboxyl group, a carboxylic acid anhydride group, and a carboxylic acid ester.
As the polyolefin having a polar group, a product obtained by copolymerizing ethylene or propylene with an unsaturated carboxylic acid (an unsaturated compound having a carboxyl group, such as acrylic acid, methacrylic acid, or maleic anhydride) or an unsaturated carboxylic acid ester, a salt obtained by neutralizing a carboxylic acid with a basic compound, and the like may be used, and in addition to those, a product obtained by copolymerizing ethylene or propylene with vinyl acetate, an epoxy-based compound, a chlorine-based compound, a urethane-based compound, a polyamide-based compound, or the like may also be used.
Specific examples of the polyolefin having a polar group include a copolymer of an acrylic acid ester and maleic anhydride, an ethylene-vinyl acetate copolymer, and an ethylene-glycidyl methacrylate copolymer.
On the other hand, when the anchor coat layer 2 contains a polyvinyl alcohol-based resin, the polyvinyl alcohol-based resin has a polar group (hydroxyl group), and since this polar group easily binds to the metal such as aluminum in the aluminum vapor-deposited layer 3, the adhesiveness between the aluminum vapor-deposited layer 3 and the anchor coat layer 2 can be easily improved. Furthermore, such an anchor coat layer 2 has excellent flexibility and can suppress cracking of the aluminum vapor-deposited layer 3 after bending (after folding). Furthermore, as the anchor coat layer 2 contains a polyvinyl alcohol-based resin, the oxygen barrier properties of the multilayer body can be improved.
The polyvinyl alcohol-based resin is a resin containing vinyl alcohol as a constituent unit, and examples of the polyvinyl alcohol-based resin include a completely saponified polyvinyl alcohol resin, a partially saponified polyvinyl alcohol resin, a modified polyvinyl alcohol resin, and an ethylene-vinyl alcohol copolymer resin. From the viewpoint of the oxygen barrier properties, it is preferable that the degree of saponification of the polyvinyl alcohol resin is higher, and the degree of saponification may be 95% or greater, or may be 98% or greater.
The anchor coat layer 2 may contain both a polyolefin having a polar group and a polyvinyl alcohol-based resin.
The anchor coat layer 2 may contain another component in addition to the above-described polyolefin having a polar group and the above-described polyvinyl alcohol-based resin. Examples of the other component include a polyolefin other than the above-described polyolefin having a polar group, a silane coupling agent, an organic titanate, a polyacrylic, a polyester, a polyurethane, a polycarbonate, a polyurea, a polyamide, a polyimide, melamine, and phenol.
The content of the above-described polyolefin having a polar group or the above-described polyvinyl alcohol-based resin in the anchor coat layer 2 may be, for example, 50% by mass or more, may be 70% by mass or more, may be 90% by mass or more, or may be 100% by mass.
The thickness of the anchor coat layer 2 may be 0.5 µm or more, may be 1 µm or more, may be 2 µm or more, may be 20 µm or less, may be 10 µm or less, or may be 5 µm or less. When the thickness of the anchor coat layer 2 is 0.5 µm or more, the surface unevenness of the above-mentioned paper substrate can be efficiently filled, and the aluminum vapor-deposited layer that will be described below can be uniformly laminated thereon. Furthermore, when the thickness of the anchor coat layer 2 is 20 µm or less, the aluminum vapor-deposited layer can be uniformly laminated while suppressing costs.
With regard to the anchor coat layer 2, the hardness measured by a nanoindentation method in a cross-section in the thickness direction of the multilayer body 10 may be 0.3 GPa or less. Such an anchor coat layer 2 has excellent flexibility, can suppress cracking of the aluminum vapor-deposited layer 3 that will be described below after bending (after folding), and at the same time, and can also improve the adhesiveness between the anchor coat layer 2 and the aluminum vapor-deposited layer 3.
Examples of the solvent included in a coating liquid for the anchor coat layer 2 include water, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, n-pentyl alcohol, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, toluene, hexane, heptane, cyclohexane, acetone, methyl ethyl ketone, diethyl ether, dioxane, tetrahydrofuran, ethyl acetate, and butyl acetate. These solvents may be used singly, or two or more kinds thereof may be used in combination. Among these, from the viewpoint of the characteristics, methyl alcohol, ethyl alcohol, isopropyl alcohol, toluene, ethyl acetate, methyl ethyl ketone, and water are preferred. Furthermore, from an environmental viewpoint, methyl alcohol, ethyl alcohol, isopropyl alcohol, and water are preferred.
Regarding a method for providing the anchor coat layer 2, the anchor coat layer 2 can be obtained by applying a coating liquid containing the above-mentioned polyolefin having a polar group or the polyvinyl alcohol-based resin, a solvent, and the like on a paper substrate, and drying the coating liquid.

[Aluminum vapor-deposited layer]

The aluminum vapor-deposited layer 3 is a layer obtained by vapor-depositing aluminum or an aluminum compound. The aluminum vapor-deposited layer may be obtained by vapor-depositing aluminum, or may contain aluminum oxide (AlO_x), silicon oxide (SiO_x), or the like.
The thickness of the aluminum vapor-deposited layer 3 may be appropriately set depending on the use application; however, the thickness is preferably 10 to 300 nm, more preferably 20 to 100 nm, and even more preferably 30 to 100 nm. When the thickness of the aluminum vapor-deposited layer 3 is set to 10 nm or more, it is easy to impart sufficient continuity to the aluminum vapor-deposited layer 3, and when the thickness is set to 300 nm or less, the occurrence of curling or cracking can be sufficiently suppressed, while it is easy to achieve sufficient gas barrier performance, oil resistance, and pliability. Furthermore, when the thickness of the aluminum vapor-deposited layer is set to 20 nm or more and 100 nm or less, the aluminum vapor-deposited layer becomes less likely to crack, and sufficient water vapor barrier properties and oil resistance can be obtained even after folding. From the viewpoint of further suppressing deterioration of the water vapor barrier properties of the multilayer body 10 when stored under high temperature and high humidity conditions, the thickness of the aluminum vapor-deposited layer 3 may be 50 to 300 nm, may be 60 to 150 nm, or may be 60 to 100 nm.
It is preferable that the aluminum vapor-deposited layer 3 is formed by vacuum film-forming means, from the viewpoints of water vapor and oxygen gas barrier performance, oil resistance, and film uniformity. Examples of the film-forming means include known methods such as a vacuum vapor deposition method, a sputtering method, and a chemical vapor phase deposition method (CVD method); however, from the viewpoint of exhibiting a high film deposition rate and high productivity, a vacuum vapor deposition method is preferred. Furthermore, among vacuum vapor deposition methods, film-forming means using electron beam heating in particular is effective because the film deposition rate can be easily controlled by the irradiation area, the electron beam current, and the like, and the temperature of the vapor deposition material can be increased or decreased in a short period of time.
The aluminum vapor-deposited layer 3 is a layer in which the half-value width of the peak of crystal plane (111) of aluminum in X-ray diffraction measurement is 1.6° or more. The above-described half-value width may be 1.8° or more, may be 2.0° or more, or may be 2.1° or more. When this half-value width is 1.6° or more, the occurrence of cracks in the aluminum vapor-deposited layer 3 can be suppressed when the multilayer body 10 is folded, and deterioration of the gas barrier properties and oil resistance after fold can be suppressed. Such an effect is more notably provided in a case where the above-described half-value width is 2.0° or more. Furthermore, when the above-described half-value width is 1.6° or more, even in a case where the multilayer body 10 is stored under high temperature and high humidity conditions (for example, in an environment at 40°C and 90%), the occurrence of permeation defects in the aluminum vapor-deposited layer 3 can be suppressed, and deterioration of the water vapor barrier properties of the multilayer body 10 can be suppressed. Such an effect is also provided more notably when the above-described half-value width is 2.0° or more. From the viewpoint of the denseness of the aluminum crystal structure, the upper limit value of the half-value width may be, for example, 15.0° or less, or may be 10.0° or less. When the resin layer in contact with the aluminum vapor-deposited layer contains an ionomer or a polyvinyl alcohol-based resin having a degree of saponification of 95% or more, the aluminum vapor-deposited layer is easily corroded. When the aluminum vapor-deposited layer has low crystallinity, such problems are likely to occur. When the above-described half-value width is 15.0° or less, even when the resin layer in contact with the aluminum vapor-deposited layer contains an ionomer or a polyvinyl alcohol-based resin having a high degree of saponification, corrosion of the aluminum vapor-deposited layer is less likely to occur. Such an effect is also more notably provided in a case where the above-described half-value width is 10.0° or less. In order to achieve both of the above-described effects, the half-value width is preferably 1.6° or more and 15.0° or less, 1.6° or more and 10.0°or less, 1.6° or more and 7.0° or less, 1.6° or more and 5.0° or less, 2.0° or more and 15.0°or less, 2.0° or more and 10.0°or less, 2.0° or more and 7.0° or less, or 2.0° or more and 5.0° or less.
The half-value width (2θ) of the peak of crystal plane (111) of aluminum in the aluminum vapor-deposited layer 3 is measured using an X-ray diffraction apparatus. As the X-ray diffraction apparatus, for example, ATX-G (trade name) manufactured by Rigaku Corporation can be used. The measurement can be carried out from above the overcoat layer 4 by using the multilayer body as a sample, and fixing the sample on a slide glass. As the X-ray diffraction of aluminum, the half-value width at the peak at 2θ = 38.5° corresponding to the plane (111) (d = 2.34) is measured. The measurement conditions are as follows.

Light source: CuKα line
Tube voltage: 50 kV
Tube current: 300 mA
Optical system: Parallel beam optical system
Scan method: 2θ/θ method
Measurement range: 30° to 50°
Sampling step: 0.02°
Scan speed: 2°/min
Slit
S1: 10.0 mm × 1.0 mm
S2: 10.0 mm × 0.5 mm
Sollar (res): 0.4 mm

The above-described half-value width can be controlled by adjusting the conditions at the time of film deposition of the aluminum vapor-deposited layer 3. For example, the half-value width can be controlled by adjusting the pressure inside the vapor deposition chamber during film deposition of the aluminum vapor-deposited layer 3. Here, when the pressure inside the vapor deposition chamber is increased, the half-value width can be increased, and when the pressure inside the vapor deposition chamber is decreased, the half-value width can be decreased. From the viewpoint that it is easy to adjust the half-value width to be 1.6° or more, the pressure inside the vapor deposition chamber during film deposition of the aluminum vapor-deposited layer 3 may be 0.05 Pa or more, may be 0.10 Pa or more, or may be 0.20 Pa or more. The upper limit value of the pressure is not particularly limited as long as it is in the range capable of film deposition of the aluminum vapor-deposited layer 3; however, for example, the upper limit value may be 0.50 Pa or less, or may be 0.40 Pa or less.

[Overcoat layer]

The overcoat layer 4 is provided on the surface of the aluminum vapor-deposited layer 3 so as to be in contact with the aluminum vapor-deposited layer 3. The overcoat layer may contain a polyolefin having a polar group.
The polyolefin having a polar group may have at least one selected from a carboxyl group, a salt of a carboxyl group, a carboxylic acid anhydride group, and a carboxylic acid ester.
As the polyolefin having a polar group, a product obtained by copolymerizing ethylene or propylene with an unsaturated carboxylic acid (an unsaturated compound having a carboxyl group, such as acrylic acid or methacrylic acid) or an unsaturated carboxylic acid ester, a salt obtained by neutralizing a carboxylic acid with a basic compound, and the like may be used, and in addition to those, a product obtained by copolymerizing ethylene or propylene with vinyl acetate, an epoxy-based compound, a chlorine-based compound, a urethane-based compound, a polyamide-based compound, or the like may also be used.
Specific examples of the polyolefin having a polar group include a copolymer of an acrylic acid ester and maleic anhydride, an ethylene-vinyl acetate copolymer, and an ethylene-glycidyl methacrylate copolymer.
By containing a polyolefin having a polar group, the overcoat layer 4 has excellent flexibility, can suppress cracking in the aluminum vapor-deposited layer after bending (after folding), and also has excellent adhesiveness to the aluminum vapor-deposited layer. In addition, by containing the above-mentioned polyolefin having a polar group, it is possible to form a dense film due to the crystallinity of the polyolefin, and water vapor barrier properties and oil resistance are exhibited. Furthermore, by having a polar group, the adhesion to the aluminum vapor-deposited layer is exhibited. Furthermore, since the overcoat layer 4 can also function as a heat seal layer by containing the above-described polyolefin having a polar group, a heat seal layer does not have to be provided separately.
The overcoat layer 4 may contain other components in addition to the above-described polyolefin having a polar group. Examples of the other components include a silane coupling agent, an organic titanate, a polyacrylic, a polyester, a polyurethane, a polycarbonate, a polyurea, a polyamide, a polyolefin-based emulsion, a polyimide, melamine, and phenol.
The content of the polyolefin having a polar group in the overcoat layer 4 may be, for example, 50% by mass or more, may be 70% by mass or more, may be 90% by mass or more, or may be 100% by mass.
The thickness of the overcoat layer 4 may be, for example, 0.05 µm or more, may be 0.5 µm or more, may be 1 µm or more, may be 2 µm or more, may be 20 µm or less, may be 10 µm or less, or may be 5 µm or less. When the thickness of the overcoat layer 4 is 0.05 µm or more, the overcoat layer 4 can sufficiently exhibit the role as the above-mentioned heat seal layer. Furthermore, when the thickness of the overcoat layer 4 is 20 µm or less, the adhesiveness to the aluminum vapor-deposited layer and the barrier properties can be sufficiently exhibited while suppressing costs. Furthermore, when the thickness of the overcoat layer 4 is set to 2 µm or more and 10 µm or less, the aluminum vapor-deposited layer becomes less likely to crack, and sufficient water vapor barrier properties and oil resistance can be obtained even after being folded.
With regard to the multilayer body 10, when a polyolefin having a polar group is incorporated into the overcoat layer 4, the thickness of the overcoat layer 4 is set to 2 µm or more and 10 µm or less, and the thickness of the aluminum vapor-deposited layer 3 is set to 20 nm or more and 100 nm or less, the aluminum vapor-deposited layer 3 becomes less likely to crack, and an effect that sufficient water vapor barrier properties and oil resistance can be obtained even after folding is particularly notably provided.
In the overcoat layer 4, the hardness measured by a nanoindentation method at a cross-section in the thickness direction of the multilayer body 10 may be 0.3 GPa or less. Such an overcoat layer 4 has excellent flexibility, can suppress cracking in the aluminum vapor-deposited layer 3 after bending (after folding), and can suppress deterioration of the gas barrier properties and oil resistance.
Examples of the solvent included in a coating liquid for the overcoat layer 4 include water, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, n-pentyl alcohol, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, toluene, hexane, heptane, cyclohexane, acetone, methyl ethyl ketone, diethyl ether, dioxane, tetrahydrofuran, ethyl acetate, and butyl acetate. These solvents may be used singly, or two or more kinds thereof may be used in combination. Among these, from the viewpoint of characteristics, methyl alcohol, ethyl alcohol, isopropyl alcohol, toluene, ethyl acetate, methyl ethyl ketone, and water are preferred. Furthermore, from an environmental viewpoint, methyl alcohol, ethyl alcohol, isopropyl alcohol, and water are preferred.
Regarding a method for providing the overcoat layer 4, the overcoat layer 4 can be obtained by applying a coating liquid containing the above-mentioned polyolefin having a polar group, a solvent, and the like on the aluminum vapor-deposited layer, and drying the coating liquid. The melting point of the polyolefin having a polar group in the coating liquid is preferably 70°C to 160°C, and more preferably 80°C to 120°C. When the melting point of the polyolefin having a polar group is low, there is an advantage that the start-up temperature during heat sealing can be made lower. When the melting point of the polyolefin having a polar group is low, there is a high risk that blocking may occur in a high temperature environment. From the viewpoint of preventing blocking, to make the contact area smaller, it is better for the particle size to be larger. Although there is no particular limitation, the particle size may be specifically 1 nm or more, may be 0.1 µm or more, and may be 1 µm or less, 0.7 µm or less, or 0.5 µm or less.

(Method for processing cross-section of measurement sample by nanoindentation method)

In the measurement by a nanoindentation method, measurement of the anchor coat layer 2 and the overcoat layer 4 is performed from a cross-section of the multilayer body 10. A multilayer body sample including an anchor coat layer 2 and an overcoat layer 4 is cut into a strip shape or a wedge shape with a razor and embedded in a resin. A photocurable resin (for example, D-800 manufactured by TOAGOSEI CO., LTD.) is used as the embedding resin, which is cured by irradiation with light after being embedded. The sample-embedded resin after curing is fixed in an insert for an AFM sample holder, trimming and cross-section cutting of the multilayer body are performed with a glass knife at normal temperature (25°C), and cross-section cutting is performed using a diamond knife under the setting of a cutting speed of 1.0 mm/s and a cut film thickness of 200 nm until a mirror surface is obtained. The cross-sectioned sample is used for the measurement by the nanoindentation method, in a state of being fixed in the insert for an AFM sample holder. As the cross-section cutting apparatus, for example, an ultramicrotome EMUC7 manufactured by Leica can be used. Furthermore, the cutting direction is set to a direction parallel to the layer interface.

(Measurement method by nanoindentation method)

The hardnesses and complex elastic moduli of the anchor coat layer and the overcoat layer represent the hardnesses and complex elastic moduli calculated by the nanoindentation method. The nanoindentation method is a measurement method in which a quasi-static indentation test is performed on a target object of measurement, and the mechanical characteristics of the sample are acquired. As the measurement apparatus, for example, Hysitron TI-Premier (trade name) manufactured by Bruker Japan K.K. can be used. As the indenter, a Berkovich type diamond indenter manufactured by Bruker Japan K.K. can be used. In the measurement by the nanoindentation method, first, a diamond indenter is scanned across a cross-section of a sample to acquire a topographical image of the sample, and the measurement position on the desired layer is specified. Thereafter, in a displacement control mode at normal temperature (25°C), indentation to a depth of 80 nm is performed at an indentation speed of 80 nm/second, subsequently the indenter is held for 1 second at the maximum depth, and then the load is removed at a speed of 80 nm/second. In the method of calculating the hardness and the complex elastic modulus, fused quartz as a standard sample is tested in advance, and the relationship between the depth of contact of the indenter with the sample and the contact projection area is calibrated. Thereafter, the unloading curve in the region of 60% to 95% for the maximum load at the time of unloading is analyzed by the Oliver-Pharr method, and the hardness and the complex elastic modulus are calculated.
The hardnesses of the anchor coat layer 2 and the overcoat layer 4 as measured by the nanoindentation method at a cross-section in the thickness direction of the multilayer body 10 may be 0.3 GPa or less. This can alleviate direct transmission of the deformation stress in the paper substrate caused by bending of the multilayer body to the aluminum vapor-deposited layer, and prevent the generation of defects in the aluminum vapor-deposited layer, deterioration of the gas barrier properties and oil resistance after bending can be suppressed. From this viewpoint, the hardnesses of the anchor coat layer 2 and the overcoat layer 4 may be 0.25 GPa or less, or may be 0.2 GPa or less. The lower limit of the hardness is not particularly limited; however, from the viewpoint of obtaining sufficient strength for maintaining the gas barrier properties and oil resistance, the lower limit can be set to 0.05 MPa or more.
In order to form a flexible anchor coat layer 2 and a flexible overcoat layer 4 in which the hardness measured by the nanoindentation method at a cross-section in the thickness direction of the multilayer body 10 is 0.3 GPa or less, the anchor coat layer 2 and the overcoat layer 4 may be formed using resin materials whose dried coating film has an elongation at break of preferably 150% or more, and more preferably 200% or more, as measured in accordance with JIS K 7161 in an atmosphere at 20°C and 65%RH.

FIG. 2 is a perspective view illustrating a gusset bag 20 formed from the multilayer body 10. A packaging bag is produced by sealing the opening at the top of the gusset bag 20. The gusset bag 20 has sites where the multilayer body 10 is folded (folded parts B1 and B2). A folded part B1 is a site where the multilayer body 10 is valley-folded as viewed from the innermost layer side, and a folded part B2 is a site where the multilayer body 10 is mountain-folded as viewed from the innermost layer side.
The packaging bag may be formed into a bag shape by folding one sheet of the multilayer body in two such that the overcoat layers 4 of the two parts face each other, subsequently appropriately folding the multilayer body into a desired shape, and then heat-sealing the resultant, or may be formed into a bag shape by superposing two sheets of the multilayer body such that the overcoat layers 4 of the two sheets face each other, and then heat-sealing the multilayer bodies.
With regard to the packaging bag according to the present embodiment, the heat seal strength may be 2 N or more, or may be 4 N or more. In addition, the upper limit value of the heat seal strength is not particularly limited; however, the upper limit value may be 10 N or less.
The packaging bag can accommodate contents such as foods and pharmaceutical products as contents. Particularly for foods, the packaging bag is suitable for accommodating confectionery and the like. The packaging bag according to the present embodiment can maintain high gas barrier properties and oil resistance even when the packaging bag has a shape with folded parts.
In the present embodiment, a gusset bag has been described as an example of the packaging bag; however, for example, a pillow bag, a three-sided sealed bag, or a standing pouch may also be produced using the multilayer body according to the present embodiment.

Examples

Hereinafter, the present disclosure will be described in more detail by way of Examples; however, the present disclosure is not intended to be limited to these examples.

(Example 1)

An aqueous dispersion of a polyolefin including a salt of a carboxyl group (manufactured by Sumitomo Seika Chemicals Company, Limited., trade name: ZAIKTHENE AC, particle size: less than 0.2 µm, solvent: water/IPA = 1/1 (mass ratio), solid content concentration: 22.5% by mass) was applied on the surface on a clay-coated layer side of a paper substrate having a clay-coated layer with a thickness of 5 µm (thickness including the clay-coated layer: 55 µm) with a bar coater, and the resulting coating was dried in an oven to form an anchor coat layer having a thickness of 3 µm.
Subsequently, Al vapor deposition was performed on the anchor coat layer by a vacuum vapor deposition method, and an Al vapor-deposited layer (aluminum vapor-deposited layer) having a thickness of 50 nm was formed. The pressure inside the vapor deposition chamber during the vapor deposition of aluminum was adjusted to the value shown in Table 1.
Next, an aqueous dispersion of a polyolefin containing a salt of a carboxyl group (manufactured by Mitsui Chemicals, Inc., trade name: CHEMIPEARL S100, particle size: less than 0.1 µm, solvent: water/IPA = 1/1 (mass ratio), solid content concentration: 20.0% by mass) was applied on the Al vapor-deposited layer with a bar coater, and the resulting coating was dried in an oven to form an overcoat layer having a thickness of 3 µm. As a result, a multilayer body was obtained.

(Example 2)

A multilayer body was obtained in the same manner as in Example 1, except that the pressure inside the vapor deposition chamber at the time of forming the Al vapor-deposited layer was changed to the value shown in Table 1.

(Example 3)

A multilayer body was obtained in the same manner as in Example 1, except that the paper substrate was changed to a paper substrate having a clay-coated layer with a thickness of 5 µm (thickness including the clay-coated layer: 50 µm).

(Example 4)

A multilayer body was obtained in the same manner as in Example 1, except that the anchor coat layer was formed by the following method. That is, an aqueous dispersion of a polyolefin containing a salt of a carboxyl group (manufactured by Mitsui Chemicals, Inc., trade name: CHEMIPEARL S100, particle size: less than 0.1 µm, solvent: water/IPA = 1/1 (mass ratio), solid content concentration: 20.0% by mass) was applied on the surface on the clay-coated layer side of a paper substrate (thickness including the clay-coated layer: 55 µm) using a bar coater, and the resulting coating was dried in an oven to form an anchor coat layer having a thickness of 3 µm.

(Example 5)

A multilayer body was obtained in the same manner as in Example 1, except that an overcoat layer was formed by the following method. That is, an aqueous dispersion of a polyolefin containing a salt of a carboxyl group (manufactured by Mitsui Chemicals, Inc., trade name: CHEMIPEARL S500, particle size: 0.7 µm, solvent: water/IPA = 1/1 (mass ratio), solid content concentration: 20.0% by mass) was applied on the Al vapor-deposited layer using a bar coater, and the resulting coating was dried in an oven to form an overcoat layer having a thickness of 3 µm.

(Examples 6 and 7)

Multilayer bodies were obtained in the same manner as in Example 1, except that the pressure inside the vapor deposition chamber at the time of forming the Al vapor-deposited layer was changed to the values shown in Table 1, and the thickness of the Al vapor-deposited layer was changed to the values shown in Table 1.

(Example 8)

A multilayer body was obtained in the same manner as in Example 1, except that the anchor coat layer was formed by the following method. That is, a solution obtained by dissolving a polyvinyl alcohol (PVA) resin having a degree of saponification of 98% and a degree of polymerization of 500 in a solvent of water/IPA = 8/2 (mass ratio) at a solid content concentration of 10% by mass, was applied on the clay-coated layer side of a paper substrate (thickness including the clay-coated layer: 55 µm) using a bar coater, and the resulting coating was dried in an oven to form an anchor coat layer having a thickness of 3 µm.

(Example 9)

A multilayer body was obtained in the same manner as in Example 8, except that the pressure inside the vapor deposition chamber at the time of forming the Al vapor-deposited layer was changed to the value shown in Table 2.

(Comparative Examples 1 and 2)

Multilayer bodies were obtained in the same manner as in Example 1, except that the pressure inside the vapor deposition chamber at the time of forming the Al vapor-deposited layer was changed to the values shown in Table 2.

(Comparative Example 3)

The following clay-coated papers 1 to 3 and non-coated paper 4 were prepared as paper substrates.

Clay-coated paper 1: The dimensional change ratios when subjected to a change from a temperature of 40°C and a relative humidity of 20%RH to a temperature of 40°C and a relative humidity of 90%RH were CD = 0.75%, MD = 0.13%, basis weight: 60 g/m²
Clay-coated paper 2: The dimensional change ratios when subjected to a change from a temperature of 40°C and a relative humidity of 20%RH to a temperature of 40°C and a relative humidity of 90%RH were CD = 0.55%, MD = 0.07%, basis weight: 60 g/m²
Clay-coated paper 3: The dimensional change ratios when subjected to a change from a temperature of 40°C and a relative humidity of 20%RH to a temperature of 40°C and a relative humidity of 90%RH were CD = 0.35%, MD = 0.15%, basis weight: 60 g/m²
Non-coated paper 4: The dimensional change ratios when subjected to a change from a temperature of 40°C and a relative humidity of 20%RH to a temperature of 40°C and a relative humidity of 90%RH were CD = 1.34%, MD = 0.03%, basis weight: 62 g/m²

(Example 10)

The clay-coated paper 1 was prepared as the paper substrate. An aqueous dispersion of a polyolefin containing a salt of a carboxyl group (manufactured by Sumitomo Seika Chemicals Company, Limited., trade name: ZAIKTHENE AC, particle size: less than 0.2 µm, solvent: water/IPA = 1/1 (mass ratio), solid content concentration: 22.5% by mass) was applied on the surface on the clay-coated layer side of the paper substrate using a gravure coater, and the resulting coating was dried in an oven to form an anchor coat layer having a thickness of 3 µm.
Subsequently, an Al vapor-deposited layer was formed on the anchor coat layer in a roll-to-roll induction heating type vacuum vapor deposition apparatus. The pressure inside the vapor deposition chamber during Al vapor deposition and the thickness of the Al vapor-deposited layer were adjusted to the values shown in Table 3.
Next, an aqueous dispersion of a polyolefin containing a salt of a carboxyl group (manufactured by Mitsui Chemicals, Inc., trade name: CHEMIPEARL S100, particle size: less than 0.1 µm, solvent: water/IPA = 1/1 (mass ratio), solid content concentration: 20.0% by mass) was applied on the Al vapor-deposited layer using a gravure coater, and the resulting coating was dried in an oven to form an overcoat layer having a thickness of 3 µm. As a result, a multilayer body was obtained.

(Example 11)

A multilayer body was obtained in the same manner as in Example 10, except that the paper substrate was changed to the clay-coated paper 2, and the pressure inside the vapor deposition chamber at the time of forming the Al vapor-deposited layer and the thickness of the Al vapor-deposited layer were changed to the values shown in Table 3.

(Example 12)

A multilayer body was obtained in the same manner as in Example 10, except that the Al vapor-deposited layer was formed by the following method. That is, the Al vapor-deposited layer was formed on the anchor coat layer in a roll-to-roll EB heating type vacuum vapor deposition apparatus. The pressure inside the vapor deposition chamber during Al vapor deposition and the thickness of the Al vapor-deposited layer were adjusted to the values shown in Table 3.

(Example 13)

A multilayer body was obtained in the same manner as in Example 12, except that the paper substrate was changed to the clay-coated paper 2.

(Example 14)

A multilayer body was obtained in the same manner as in Example 12, except that the paper substrate was changed to the clay-coated paper 3.

(Example 15)

The clay-coated paper 2 was prepared as the paper substrate. A solution obtained by dissolving a polyvinyl alcohol having a degree of saponification of 98% and a degree of polymerization of 500 (manufactured by Kuraray Co., Ltd., trade name: POVAL 5-98) in a solvent of water/IPA = 8/2 (mass ratio) at a solid content concentration of 10% by mass, was applied on the surface on the clay-coated layer side of the paper substrate using a gravure coater, and the resulting coating was dried in an oven to form an anchor coat layer having a thickness of 4 µm.
Subsequently, an Al vapor-deposited layer was formed on the anchor coat layer in a roll-to-roll EB heating type vacuum vapor deposition apparatus. The pressure inside the vapor deposition chamber during Al vapor deposition and the thickness of the Al vapor-deposited layer were adjusted to the values shown in Table 3.
Next, an aqueous dispersion of a polyolefin containing a salt of a carboxyl group (manufactured by Mitsui Chemicals, Inc., trade name: CHEMIPEARL S500, particle size: 0.7 µm, solvent: water/IPA = 1/1 (mass ratio), solid content concentration: 20.0% by mass) was applied on the Al vapor-deposited layer using a gravure coater, and the resulting coating was dried in an oven to form an overcoat layer having a thickness of 3 µm. As a result, a multilayer body was obtained.

(Example 16)

A multilayer was obtained in the same manner as in Example 15, except that the paper substrate was changed to the clay-coated paper 1, and the pressure inside the vapor deposition chamber at the time of forming the Al vapor-deposited layer and the thickness of the Al vapor-deposited layer were changed to the values shown in Table 3.

(Example 17)

The non-coated paper 4 was prepared as the paper substrate. A solution obtained by dissolving a polyvinyl alcohol having a degree of saponification of 98% and a degree of polymerization of 500 (manufactured by Kuraray Co., Ltd., trade name: POVAL 5-98) in a solvent of water/IPA = 8/2 (mass ratio) at a solid content concentration of 10% by mass, was applied on one surface of the paper substrate using a gravure coater, and the resulting coating was dried in an oven to form an anchor coat layer having a thickness of 3 µm.
Subsequently, an Al vapor-deposited layer was formed on the anchor coat layer in a roll-to-roll EB heating type vacuum vapor deposition apparatus. The pressure inside the vapor deposition chamber during Al vapor deposition and the thickness of the Al vapor-deposited layer were adjusted to the values shown in Table 4.
Next, an aqueous dispersion of an ethylene-acrylic acid copolymer resin (manufactured by Michelman, Inc., trade name: MC9100, solid content concentration: 20% by mass) was applied on the Al vapor-deposited layer using a gravure coater, and the resulting coating was dried in an oven to form an overcoat layer having a thickness of 3 µm. As a result, a multilayer body was obtained.

(Comparative Examples 4 to 6)

Multilayer bodies were obtained in the same manner as in Example 10, except that the pressure inside the vapor deposition chamber at the time of forming the Al vapor-deposited layer and the thickness of the Al vapor-deposited layer were changed to the values shown in Table 4.

(Comparative Example 7)

A multilayer body was obtained in the same manner as in Example 12, except that the pressure inside the vapor deposition chamber at the time of forming the Al vapor-deposited layer and the thickness of the Al vapor-deposited layer were changed to the values indicated in Table 4.

(Comparative Example 8)

A multilayer body was obtained in the same manner as in Example 15, except that the pressure inside the vapor deposition chamber at the time of forming the Al vapor-deposited layer and the thickness of the Al vapor-deposited layer were changed to the values indicated in Table 4.

A multilayer body was embedded in a UV-curable resin and subjected to cross-section cutting using a cryomicrotome to produce a cross-section observation sample. The cross-section of this sample was observed under an electron microscope at a magnification of 50000 times, and a SEM image was acquired. The thickness of the Al vapor-deposited layer was measured from the obtained SEM image. The results are shown in Table 1 to Table 4.

<X-ray diffraction measurement>

Measurement of the half-value width of the peak of crystal plane (111) of aluminum in the Al vapor-deposited layer was carried out by the following procedure. For the measurement of the half-value width, an X-ray diffraction apparatus (trade name: ATX-G) manufactured by Rigaku Corporation was used. CuKα line was used as the light source, the tube voltage was set to 50 kV, the tube current was set to 300 mA, a parallel beam optical system was used as the optical system, the scanning method was 2θ/θ method, the measurement range was set to 30° to 50°, and the scan speed was set to 2°/min. Furthermore, the sampling step was set to 0.02°, and the slits were set to S1: 10.0 mm × 1.0 mm, S2: 10.0 mm × 0.5 mm, and Sollar (res): 0.4 mm. Each of the multilayer bodies obtained in Examples and Comparative Examples was used as a sample, the paper substrate side of the multilayer body was stuck onto a slide glass using a double-sided tape, and X-ray diffraction measurement was performed. As the X-ray diffraction of aluminum, the half-value width at the peak at 2θ = 38.5° corresponding to the plane (111) (d = 2.34) was measured. The results are shown in Table 1 to Table 4.

Samples for measuring the hardnesses and the complex elastic moduli of the anchor coat layer and the overcoat layer from cross-sections of the multilayer bodies obtained in Examples and Comparative Examples were produced by the following procedure. First, a multilayer body was cut with a razor such that a sample including an anchor coat layer and an overcoat layer would have a strip shape or a wedge shape, and the obtained sample was embedded in a resin. D-800 photocurable resin manufactured by TOAGOSEI CO., LTD. was used as the embedding resin, and this was cured by irradiation with light after embedding. The sample-embedded resin after curing was fixed in an insert for an AFM sample holder, trimming and cross-section cutting of the film were performed at normal temperature (25°C) using a glass knife, and cross-section cutting was performed using a diamond knife at a cutting speed of 1.0 mm/sec and a cutting film thickness of 200 nm until a mirror surface was obtained. The cross-sectioned sample was used for the measurement by a nanoindentation method, in a state of being fixed in an insert for an AFM sample holder. As the cross-section cutting apparatus, an ultramicrotome EMUC7 manufactured by Leica was used. Furthermore, the cutting direction was set to a direction parallel to the layer interface.

The hardnesses and the complex elastic moduli of the anchor coat layer and the overcoat layer represent the hardnesses and complex elastic moduli calculated by a nanoindentation method. The nanoindentation method is a measurement method in which a quasi-static indentation test is performed on a target object of measurement, and the mechanical characteristics of the sample are acquired. As the measurement apparatus, Hysitron TI-Premier (trade name) manufactured by Bruker Japan K.K. was used. As the indenter, a Berkovich type diamond indenter manufactured by Bruker Japan K.K. was used. In the measurement by the nanoindentation method, first, a diamond indenter was scanned across a cross-section of the sample to acquire a topographical image of the sample, and the measurement position on the desired layer was specified. Thereafter, in a displacement control mode at normal temperature (25°C), indentation to a depth of 80 nm was performed at an indentation speed of 80 nm/second, subsequently the indenter was held for 1 second at the maximum depth, and then the load was removed at a speed of 80 nm/second. In the method of calculating the hardness and the complex elastic modulus, fused quartz as a standard sample was tested in advance, and the relationship between the depth of contact of the indenter with the sample and the contact projection area was calibrated. Thereafter, the unloading curve in the region of 60% to 95% for the maximum load at the time of unloading was analyzed by the Oliver-Pharr method, and the hardness and the complex elastic modulus were calculated. The results are shown in Table 1 to Table 4.

In the measurement of the elongation at break of the anchor coat layer and the overcoat layer, coating liquids for forming the anchor coat layer and the overcoat layer were applied on a supporting substrate and dried, the resulting coatings were peeled from the supporting substrate, the layers were punched into a type 1A dumbbell shape to obtain a test piece, and the elongation at break was measured based on the method described in JIS K7161. As the apparatus, an Autograph testing machine AGS-X (manufactured by SHIMADZU CORPORATION) was used, the tensile test speed was set to 50 mm/min, and measurement was made in an environment at a temperature of 20°C and a humidity of 65%. The results are shown in Table 1 to Table 4.

The degree of oil resistance (KIT value) of the surface on the overcoat layer side of the multilayer bodies obtained in Examples and Comparative Examples was measured by the TAPPI UM-557 method (KIT method). Furthermore, while a roller weighing 1500 g was rolled at a speed of 300 mm/min, a crease parallel to the MD direction was provided in the multilayer body such that the multilayer body was valley-folded as viewed from the paper substrate side (with the overcoat layer on the outer surface), and the degree of oil resistance (KIT value) of the crease portion of the multilayer body after unfolding was also measured in the same manner. The KIT value is expressed as grade 0 to grade 12, and a higher number indicates a higher degree of oil resistance. The highest point of the degree of oil resistance given by the KIT test liquid that shows no penetration was regarded as the evaluation result. The KIT value is preferably 6 or more, and when the value is smaller than 6, the oil resistance for food packaging may be insufficient. The results are shown in Table 1 to Table 4.

For the multilayer bodies obtained in Examples and Comparative Examples, the water vapor transmission rate (g/m²/day) in an atmosphere of 40°C and 90%RH was measured by the Mocon method according to JIS K7129-2. For the measurement, a water vapor transmission rate measuring apparatus (manufactured by MOCON, Inc., trade name: PERMATRAN-W3/34G) was used. Furthermore, the multilayer body was stored in a constant-temperature constant-humidity chamber at 40°C and 90%RH for one week, and then the same measurement was performed. The initial water vapor transmission rate and the water vapor transmission rate after storage at 40°C and 90% are shown in Table 1 to Table 4.

[Table 1]

		Example 1	Example 2	Example 3	Example 4	Example 5	Example 6	Example 7
Paper substrate (thickness)		Paper + clay-coated layer (50 µm + 5 µm)	Paper + clay-coated layer (50 µm + 5 µm)	Paper + clay-coated layer (45 µm + 5 µm)	Paper + clay-coated layer (50 µm + 5 µm)	Paper + clay-coated layer (50 µm + 5 µm)	Paper + clay-coated layer (50 µm + 5 µm)	Paper + clay-coated layer (50 µm + 5 µm)
Anchor coat layer (thickness)		ZAIKTHENE AC (3 µm)	ZAIKTHENE AC (3 µm)	ZAIKTHENE AC (3 µm)	CHEMIPEARL S100 (3 µm)	ZAIKTHENE AC (3 µm)	ZAIKTHENE AC (3 µm)	ZAIKTHENE AC (3 µm)
Vapor-deposited layer (thickness)		Al (50 nm)	Al (50 nm)	Al (50 nm)	Al (50 nm)	Al (50 nm)	Al (20 nm)	Al (100 nm)
Overcoat layer (thickness)		CHEMIPEARL S100 (3 µm)	CHEMIPEARL S100 (3 µm)	CHEMIPEARL S100 (3 µm)	CHEMIPEARL S100 (3 µm)	CHEMIPEARL S500 (3 µm)	CHEMIPEARL S100 (3 µm)	CHEMIPEARL S100 (3 µm)
Pressure during vapor deposition [Pa]		0.19	0.11	0.19	0.19	0.19	0.28	0.15
Half-value width [°]		2.71	2.12	2.71	2.71	2.71	3.14	2.59
Hardness [GPa]	Anchor coat layer	0.02	0.02	0.02	0.04	0.02	0.02	0.02
Hardness [GPa]	Overcoat layer	0.04	0.04	0.04	0.04	0.04	0.04	0.04
Complex elastic modulus [GPa]	Anchor coat layer	0.54	0.54	0.54	0.64	0.54	0.54	0.54
Complex elastic modulus [GPa]	Overcoat layer	0.64	0.64	0.64	0.64	0.50	0.64	0.64
Elongation at break [%]	Anchor coat layer	400	400	400	350	400	400	400
Elongation at break [%]	Overcoat layer	350	350	350	350	400	350	350
KIT value	Initial	12	12	12	12	12	12	12
KIT value	After folding	12	12	12	12	12	12	12
Water vapor transmission rate [g/m²/day]	Initial	1.5	1.2	1.6	1.5	1.5	3.0	0.8
Water vapor transmission rate [g/m²/day]	After storage	3.2	4.5	3.5	3.0	3.2	5.8	1.5

[Table 2]

		Example 8	Example 9	Comparative Example 1	Comparative Example 2	Comparative Example 3
Paper substrate (thickness)		Paper + clay-coated layer (50 µm + 5 µm)	Paper + clay-coated layer (50 µm + 5 µm)	Paper + clay-coated layer (50 µm + 5 µm)	Paper + clay-coated layer (50 µm + 5 µm)	Paper + clay-coated layer (50 µm + 5 µm)
Anchor coat layer (thickness)		PVA (3 µm)	PVA (3 µm)	ZAIKTHENE AC (3 µm)	ZAIKTHENE AC (3 µm)	PVA (3 µm)
Vapor-deposited layer (thickness)		Al (50nm)	Al (50nm)	Al (50nm)	Al (50nm)	Al (50nm)
Overcoat layer (thickness)		CHEMIPEARL S100 (3 µm)	CHEMIPEARL S100 (3 µm)	CHEMIPEARL 5100 (3 µm)	CHEMIPEARL 5100 (3 µm)	CHEMIPEARL 5100 (3 µm)
Pressure during vapor deposition [Pa]		0.19	0.11	0.07	0.02	0.07
Half-value width [°]		2.71	2.12	1.51	0.49	1.51
Hardness [GPa]	Anchor coat layer	0.19	0.19	0.02	0.02	0.19
Hardness [GPa]	Overcoat layer	0.04	0.04	0.04	0.04	0.04
Complex elastic modulus [GPa]	Anchor coat layer	5.70	5.70	0.54	0.54	5.70
Complex elastic modulus [GPa]	Overcoat layer	0.64	0.64	0.64	0.64	0.64
Elongation at break [%]	Anchor coat layer	180	180	400	400	180
Elongation at break [%]	Overcoat layer	350	350	350	350	350
KIT value	Initial	12	12	12	12	12
KIT value	After folding	12	12	4	3	3
Water vapor transmission rate [g/m²/day]	Initial	1.2	1.0	1.2	1.0	0.8
Water vapor transmission rate [g/m²/day]	After storage	2.0	2.0	10.9	9.5	12.3

[Table 3]

		Example 10	Example 11	Example 12	Example 13	Example 14	Example 15	Example 16
Paper substrate (thickness)		Clay-coated paper 1	Clay-coated paper 2	Clay-coated paper 1	Clay-coated paper 2	Clay-coated paper 3	Clay-coated paper 2	Clay-coated paper 1
Anchor coat layer (thickness)		ZAIKTHENE AC (3 µm)	ZAIKTHENE AC (3 µm)	ZAIKTHENE AC (3 µm)	ZAIKTHENE AC (3 µm)	ZAIKTHENE AC (3 µm)	PVA5-98 (4 µm)	PVA5-98 (4 µm)
Vapor-deposited layer (thickness)		Al (80 nm)	Al (70 nm)	Al (60 nm)	Al (60 nm)	Al (60 nm)	Al (100 nm)	Al (80 nm)
Overcoat layer (thickness)		CHEMIPEARL S100 (3 µm)	CHEMIPEARL S100 (3 µm)	CHEMIPEARL S100 (3 µm)	CHEMIPEARL S100 (3 µm)	CHEMIPEARL S100 (3 µm)	CHEMIPEARL S500 (3 µm)	CHEMIPEARL S500 (3 µm)
Pressure during vapor deposition [Pa]		0.34	0.05	0.11	0.11	0.11	0.40	0.25
Half-value width [°]		2.50	2.40	6.20	10.70	6.00	6.20	10.70
Hardness [GPa]	Anchor coat layer	0.02	0.02	0.02	0.02	0.02	0.19	0.19
Hardness [GPa]	Overcoat layer	0.04	0.04	0.04	0.04	0.04	0.04	0.04
Complex elastic modulus [GPa]	Anchor coat layer	0.54	0.54	0.54	0.54	0.54	5.70	5.70
Complex elastic modulus [GPa]	Overcoat layer	0.64	0.64	0.64	0.64	0.64	0.50	0.50
Elongation at break [%]	Anchor coat layer	400	400	400	400	400	180	180
Elongation at break [%]	Overcoat layer	350	350	350	350	350	400	400
KIT value	Initial	12	12	12	12	12	12	12
KIT value	After folding	8	11	12	12	12	12	12
Water vapor	Initial	0.5	1.4	1.2	0.6	0.7	0.6	1.3
transmission rate [g/m²/day]	After storage	1.3	4.2	2.0	1.0	1.0	2.0	2.8

[Table 4]

		Example 17	Comparative Example 4	Comparative Example 5	Comparative Example 6	Comparative Example 7	Comparative Example 8
Paper substrate (thickness)		Non-coated paper 4	Clay-coated paper 1	Clay-coated paper 1	Clay-coated paper 1	Clay-coated paper 1	Clay-coated paper 2
Anchor coat layer (thickness)		181062PX (3 µm)	ZAIKTHENE AC (3 µm)	ZAIKTHENE AC (3 µm)	ZAIKTHENE AC (3 µm)	ZAIKTHENE AC (3 µm)	PVA5-98 (4 µm)
Vapor-deposited layer (thickness)		Al (140 nm)	Al (60 nm)	Al (73 nm)	Al (68 nm)	Al (50 nm)	Al (50 nm)
Overcoat layer (thickness)		MC9100 (3 µm)	CHEMIPEARL S100 (3 µm)	CHEMIPEARL S100 (3 µm)	CHEMIPEARL S100 (3 µm)	CHEMIPEARL S100 (3 µm)	CHEMIPEARL S500 (3 µm)
Pressure during vapor deposition [Pa]		0.15	0.03	0.02	0.03	0.05	0.05
Half-value width [°]		14.60	1.50	1.00	1.40	1.50	1.50
Hardness [GPa]	Anchor coat layer	-	0.02	0.02	0.02	0.02	0.19
Hardness [GPa]	Overcoat layer	-	0.04	0.04	0.04	0.04	0.04
Complex elastic modulus [GPa]	Anchor coat layer	-	0.54	0.54	0.54	0.54	5.70
Complex elastic modulus [GPa]	Overcoat layer	-	0.64	0.64	0.64	0.64	0.50
Elongation at break [%]	Anchor coat layer	-	400	400	400	400	180
Elongation at break [%]	Overcoat layer	-	350	350	350	350	400
KIT value	Initial	12	12	12	12	12	12
KIT value	After folding	12	5	4	5	3	4
Water vapor transmission rate [g/m²/day]	Initial	1.1	1.5	1.4	3.0	1.0	0.9
Water vapor transmission rate [g/m²/day]	After storage	1.5	8.6	9.7	19.2	8.1	9.9

As shown in Table 1 to Table 4, the multilayer bodies of the Examples had satisfactory degrees of oil resistance (KIT value) not only initially but also after folding. Furthermore, as shown in Table 1 to Table 4, it was confirmed that the multilayer bodies of the Examples maintained a water vapor transmission rate of 6 g/m²/day or less after being stored at 40°C and 90%RH for one week, demonstrating satisfactory water vapor barrier properties.

Reference Signs List

1: paper substrate, 2: anchor coat layer, 3: aluminum vapor-deposited layer, 4: overcoat layer, 10: multilayer body, 20: gusset bag, B1, B2: folded part.

Claims

A multilayer body comprising a structure in which at least a paper substrate, an anchor coat layer, an aluminum vapor-deposited layer, and an overcoat layer are laminated in this order,
wherein in the aluminum vapor-deposited layer, a half-value width of a peak of crystal plane (111) of aluminum in X-ray diffraction measurement is 1.6° or more.
The multilayer body according to claim 1, wherein the anchor coat layer contains a polyolefin having a polar group or a polyvinyl alcohol-based resin.
The multilayer body according to claim 1, wherein the overcoat layer contains a polyolefin having a polar group.
The multilayer body according to claim 1, wherein a hardness of the anchor coat layer as measured by a nanoindentation method at a cross-section in a thickness direction of the multilayer body is 0.3 GPa or less.
The multilayer body according to claim 1, wherein a hardness of the overcoat layer as measured by a nanoindentation method at a cross-section in a thickness direction of the multilayer body is 0.3 GPa or less.
The multilayer body according to claim 1, wherein the aluminum vapor-deposited layer has a thickness of 20 nm or more and 100 nm or less.
The multilayer body according to claim 1, wherein in the aluminum vapor-deposited layer, a half-value width of a peak of crystal plane (111) of aluminum in X-ray diffraction measurement is 2.0° or more and 15.0° or less.
The multilayer body according to claim 7, wherein the aluminum vapor-deposited layer is in contact with a resin layer containing an ionomer or a polyvinyl alcohol-based resin having a degree of saponification of 95% or more.
A packaging bag comprising the multilayer body according to any one of claims 1 to 8.
The packaging bag according to claim 9, having a folded part.