Multilayer structure and packaging material including same

Abstract

Provided is a multilayer structure in which a vapor-deposited film (X) including a vinyl alcohol-based polymer layer (A) and a vapor-deposited layer (B) made of silicon oxide or a metal oxide, and a polyolefin layer (C) are laminated, wherein when the vinyl alcohol-based polymer layer (A)-side surface of the vapor-deposited layer (B) is referred to as surface (b1) and the reverse surface of the vapor-deposited layer (B) is referred to as surface (b2), the ratio [(O / M)b1 / (O / M)c] of the molar ratio (O / M)b1 of oxygen element (O) to silicon element or metal element (M) in surface (b1) to the molar ratio (O / M)c of oxygen element (O) to silicon element or metal element (M) at a position equidistant from surface (b1) and surface (b2) is 1.1-1.7 as determined from an elemental analysis performed for the vapor-deposited layer (B) in the depth direction from surface (b2) to surface (b1) by a scanning X-ray photoelectron spectroscopic analyzer, and the proportion in thickness of the polyolefin layer is 75% or more. Accordingly, a multilayer structure containing a vapor-deposited film having excellent gas barrier properties and flex resistance is provided.

Description

Multilayer structure and packaging material containing the same

[0001] The present invention relates to a multilayer structure comprising a vapor-deposited film including a vinyl alcohol-based polymer layer and a vapor-deposited layer.The present invention also relates to a packaging material comprising the multilayer structure.The present invention also relates to a package comprising the packaging material and contents housed therein.The present invention also relates to a recovered composition comprising recovered material from the multilayer structure.The present invention also relates to a method for recovering the multilayer structure.

[0002] Packaging materials for long-term food storage are often required to have gas barrier properties, including oxygen barrier properties. The use of packaging materials with high gas barrier properties can prevent oxidative deterioration of food caused by oxygen penetration and the growth of microorganisms. Metal foils such as aluminum foils, metal vapor deposition layers, and inorganic oxide vapor deposition layers such as silicon oxide and aluminum oxide are widely used as inorganic layers for improving gas barrier properties (Patent Document 1).

[0003] Meanwhile, in recent years, driven by environmental and waste issues, there has been a growing global demand for so-called post-consumer recycling (hereinafter sometimes simply referred to as "recycling"), which involves recovering and recycling packaging materials consumed in the market. Recycling typically involves cutting recovered packaging materials, separating and cleaning them as necessary, and then melt-mixing them using an extruder. In this regard, packaging materials are required to be composed of as few materials as possible (mono-materialization), which allows for the production of high-purity, high-quality recycled raw materials. In particular, aluminum foil and polyester film are known to hinder recyclability due to their poor compatibility and dispersibility with polyolefin-based resins, which are widely used as packaging materials. Therefore, multilayer structures containing inorganic vapor-deposited films with a polyolefin-based resin substrate are in demand, instead of multilayer structures containing inorganic vapor-deposited films with aluminum foil or polyester film substrates. For example, Patent Document 2 proposes a vapor-deposited multilayer film in which an inorganic vapor-deposited layer is laminated on the surface of the EVOH layer of a polyethylene-based multilayer film, the outermost layer of which is an EVOH layer, thereby achieving both gas barrier properties and recyclability.

[0004] Japanese Patent Application Laid-Open No. 62-101428 International Publication No. 2021 / 261560

[0005] However, when packaging materials using the above-mentioned conventional multilayer films, particularly vapor-deposited multilayer films in which an inorganic vapor-deposited layer is laminated on the surface of the EVOH layer of a polyolefin-based multilayer film in which the EVOH layer is the outermost layer, are used to achieve mono-materialization, it has been found that the gas barrier properties deteriorate when the packaging materials are bent or when they are stored for a certain period of time in a packaged state containing contents containing a specific amount of moisture or oil.

[0006] In view of the above circumstances, an object of the present invention is to provide a multilayer structure, and a packaging material and a package using the same, which are vapor-deposited films having an inorganic layer on the surface of a vinyl alcohol-based polymer layer, and which can suppress deterioration in gas barrier properties even when the films are bent or when the films are stored for a certain period of time in a state where contents containing specific amounts of moisture or oil are packaged in the films. Another object of the present invention is to provide a recovered composition containing recovered multilayer structures, and a method for recovering the multilayer structures.

[0007] As a result of extensive research into achieving the above-mentioned object, the present inventors have found that it is possible to (1) use a vinyl alcohol-based polymer layer as a substrate on which a vapor-deposited layer is formed, (2) form a vapor-deposited layer made of silicon oxide or a metal oxide, and (3) blow in an appropriate amount of oxygen gas when forming the vapor-deposited layer, thereby appropriately segregating oxygen element in the vapor-deposited layer, thereby obtaining a multilayer structure that is excellent in gas barrier properties, flex resistance, and storage stability when packaging contents containing specific amounts of moisture, oil, etc., and have completed the present invention.

[0008] That is, the present invention is as follows: [1] A multilayer structure obtained by laminating a vapor-deposited film (X) including a vinyl alcohol-based polymer layer (A) and a vapor-deposited layer (B) made of silicon oxide or a metal oxide, and a polyolefin layer (C), wherein the vapor-deposited layer (B) having a thickness of 30 nm to 200 nm is formed directly on the surface of the vinyl alcohol-based polymer layer (A), wherein the surface of the vapor-deposited layer (B) facing the vinyl alcohol-based polymer layer (A) is designated as surface (b1) and the surface opposite to the vapor-deposited layer (B) is designated as surface (b2), and when elemental analysis of the vapor-deposited layer (B) is performed in the depth direction from surface (b2) to surface (b1) using a scanning X-ray photoelectron spectrometer, the molar ratio (O / M) of oxygen element (O) to silicon element or metal element (M) in surface (b1) is ｂ１ and the molar ratio (O / M) of oxygen element (O) to silicon element or metal element (M) at positions equidistant from the surface (b1) and the surface (b2). ｃ The ratio [(O / M) ｂ１ / (O / M) ｃ

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[0110] ｂ１ [5] The multilayer structure according to any one of [1] to [3], wherein the molar ratio (O / M) is 1.85 or more and 2.35 or less. ｃThe multilayer structure according to any one of [1] to [4], wherein the value of (R) is 1.5 or more and 2.0 or less. [6] The multilayer structure according to any one of [1] to [5], wherein the vapor-deposited film (X) comprises a polyolefin substrate layer (G), a polyolefin-based adhesive layer (H), a vinyl alcohol-based polymer layer (A), and a vapor-deposited layer (B) in this order. [7] The multilayer structure according to [6], wherein the polyolefin substrate layer (G), the polyolefin-based adhesive layer (H), and the vinyl alcohol-based polymer layer (A) are coextruded. [8] The multilayer structure according to [6] or [7], wherein the polyolefin substrate layer (G), the polyolefin-based adhesive layer (H), and the vinyl alcohol-based polymer layer (A) are stretched in at least one direction. [9] The multilayer structure according to any one of [6] to [8], wherein the vinyl alcohol-based polymer layer (A) comprises, as a main component, an ethylene-vinyl alcohol copolymer having an ethylene unit content of 10 to 65 mol% and a saponification degree of 90 mol% or more.

[10] The multilayer structure according to any one of [1] to [5], wherein the vapor-deposited film (X) comprises a polyolefin substrate layer (G), a vinyl alcohol-based polymer layer (A), and a vapor-deposited layer (B) in this order.

[11] The multilayer structure according to

[10] , wherein the vinyl alcohol-based polymer layer (A) is formed by coating a solution or dispersion of a vinyl alcohol-based polymer on the polyolefin substrate layer (G).

[12] The multilayer structure according to

[10] or

[11] , wherein the vinyl alcohol-based polymer layer (A) contains, as a main component, a vinyl alcohol-based polymer having an ethylene unit content of 50 mol% or less and a saponification degree of 70 mol% or more.

[13] The multilayer structure according to any one of [1] to

[12] , wherein the multilayer structure has a plurality of polyolefin layers (C), one of which is an unstretched polyolefin layer and the other is an oriented polyolefin layer.

[14] The multilayer structure according to any one of [1] to

[13] , wherein the multilayer structure does not contain a layer containing, as a main component, a resin having a melting point of 200°C or higher or a metal layer having a thickness of 1 μm or more.

[15] A packaging material comprising the multilayer structure according to any one of [1] to

[14] .

[16] A package comprising the packaging material according to

[15] and a content therein, wherein the content contains 5% by mass or more of water and at least one selected from the group consisting of 1% by mass or more of lipids, 1% by mass or more of sodium chloride, and 0.5% by mass or more of acetic acid.

[17] A recovered composition comprising a recovered multilayer structure according to any one of [1] to

[14] .

[18] A method for recovering a multilayer structure, comprising crushing the multilayer structure according to any one of [1] to

[14] and then melt-molding the crushed multilayer structure.

[0009] The multilayer structure of the present invention has excellent gas barrier properties and can maintain high gas barrier properties even when subjected to physical stress such as bending. This provides a multilayer structure that has excellent bending resistance and barrier stability even when packed with contents containing specific amounts of moisture, oil, etc., and therefore has excellent storage stability for the contents. Therefore, the multilayer structure of the present invention is suitable as a packaging material for packaging foods, etc. Furthermore, the multilayer structure of the present invention can be easily recovered and melt-molded again.

[0010] 1 is a graph plotting the molar ratios of silicon (Si), oxygen (O), and carbon (C) (total 100 mol%) against sputtering time when the vapor-deposited layer (B) described in Example 2 was analyzed with a scanning X-ray photoelectron spectrometer. FIG. 2 is a graph plotting the molar ratio (O / Si) calculated from FIG. 1 against sputtering time. FIG. 3 is a graph plotting the molar ratios of silicon (Si), oxygen (O), and carbon (C) (total 100 mol%) against sputtering time when the vapor-deposited layer (B) described in Comparative Example 5 was analyzed with a scanning X-ray photoelectron spectrometer. FIG. 4 is a graph plotting the molar ratio (O / Si) calculated from FIG. 3 against sputtering time.

[0011] Unless otherwise specified, "gas barrier properties" herein refer to the ability to barrier gases other than water vapor. Furthermore, in this specification, the term "barrier properties" refers to both gas barrier properties and water vapor barrier properties. The ability to maintain high barrier properties even when subjected to physical stress such as bending is sometimes referred to as "flex resistance." Furthermore, when describing layer structures, " / " indicates direct lamination, and " / / " indicates lamination either directly or via an adhesive layer. The term "outermost layer" does not refer to the layer present on the front side, distinguishing between the front and back sides. In other words, a vapor-deposited film or multilayer structure consisting of two or more layers has two outermost layers: one on one side and the other on the other side. Furthermore, in structures with a distinct inside and outside, such as a bag or container, the innermost layer is sometimes referred to as the innermost layer, and the outermost layer is sometimes referred to as the outermost layer. The term "major component" refers to the component with the highest content by mass. In this specification, the "thickness" of a layer or film refers to the average value of thicknesses measured at any five points.

[0012] <Vapor-deposited film> The vapor-deposited film of the present invention is a vapor-deposited film (X) comprising a vinyl alcohol-based polymer layer (A) and a vapor-deposited layer (B) made of silicon oxide or metal oxide, in which the vapor-deposited layer (B) having a thickness of 30 nm or more and 200 nm or less is formed directly on the surface of the vinyl alcohol-based polymer layer (A), and when the surface of the vapor-deposited layer (B) facing the vinyl alcohol-based polymer layer (A) is designated as surface (b1) and the surface opposite to the vapor-deposited layer (B) is designated as surface (b2), elemental analysis of the vapor-deposited layer (B) in the depth direction from surface (b2) to surface (b1) using a scanning X-ray photoelectron spectrometer reveals that the molar ratio (O / M) of oxygen element (O) to silicon element or metal element (M) in surface (b1) is ｂ１ and the molar ratio (O / M) of oxygen element (O) to silicon element or metal element (M) at positions equidistant from the surface (b1) and the surface (b2). ｃ The ratio [(O / M) ｂ１ / (O / M) ｃ ] is 1.1 or more and 1.7 or less.

[0013] The vapor-deposited film (X) of the present invention has excellent gas barrier properties and flex resistance. The reason for this is unclear, but the following reason is presumed. In the vapor-deposited film (X), oxygen atoms segregate near the interface between the vinyl alcohol-based polymer layer (A) and the vapor-deposited layer (B), presumably increasing the adhesion strength between the vinyl alcohol-based polymer layer (A) and the vapor-deposited layer (B). This is presumed to maintain strong adhesion between the vinyl alcohol-based polymer layer (A) and the vapor-deposited layer (B) even when the vapor-deposited film is subjected to a flexing treatment, thereby suppressing deterioration of the gas barrier properties after the flexing treatment. Furthermore, even when contents containing a large amount of moisture, oil, etc. are packaged, the vinyl alcohol-based polymer layer (A) maintains strong adhesion to the vapor-deposited layer (B), presumably suppressing deterioration of the contents.

[0014] (Vinyl alcohol-based polymer layer (A)) The vinyl alcohol-based polymer layer (A) contains a vinyl alcohol-based polymer as a main component. The vinyl alcohol-based polymer may be any polymer containing a vinyl alcohol unit, and may be polyvinyl alcohol (hereinafter may be referred to as PVOH) or an ethylene-vinyl alcohol copolymer (hereinafter may be referred to as EVOH). When the vinyl alcohol-based polymer layer (A) is formed by melt molding, an ethylene-vinyl alcohol copolymer is suitable.

[0015] PVOH is a polymer having vinyl alcohol units as monomer units. PVOH is usually obtained by saponifying polyvinyl ester. The lower limit of the ratio of vinyl alcohol units to all monomer units in PVOH is preferably 50 mol%, more preferably 60 mol%, and even more preferably 70 mol%. By setting the ratio of vinyl alcohol units to the above lower limit or higher, good water solubility and the like are exhibited. On the other hand, the upper limit of the ratio of the vinyl alcohol units may be 100 mol%, but is preferably 99.99 mol%, and more preferably 99 mol%.

[0016] The lower limit of the saponification degree of PVOH is preferably 35 mol%, more preferably 50 mol%, even more preferably 70 mol%, and particularly preferably 75 mol%. On the other hand, the upper limit of the saponification degree may be 100 mol%, but may be preferably 99 mol%, more preferably 95 mol%, even more preferably 92 mol%, and particularly preferably less than 88 mol%. By setting the saponification degree within the above range, the surface tension can be effectively reduced. The saponification degree is a value measured by the method described in JIS K6726:1994.

[0017] The average degree of polymerization of PVOH is not particularly limited, but is preferably 200 or more, more preferably 400 or more, even more preferably 600 or more, and particularly preferably 800 or more. The average degree of polymerization is preferably 5,000 or less, more preferably 4,000 or less, and even more preferably 3,000 or less. By setting the average degree of polymerization within the above range, it is possible to effectively reduce the surface tension while suppressing the viscosity increase of the solution. The average degree of polymerization is the viscosity-average degree of polymerization measured in accordance with JIS K6726:1994. That is, the PVOH is resaponified to a saponification degree of 99.5 mol% or more, purified, and then the intrinsic viscosity [η] (unit: liter / g) measured in water at 30°C is used to calculate the viscosity-average degree of polymerization using the following formula: Viscosity-average degree of polymerization = ([η] x 10 ４ / 8.29) （１／０．６２）

[0018] EVOH is usually obtained by saponifying a copolymer of ethylene and a vinyl ester such as vinyl acetate, vinyl formate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl pivalate, and vinyl versatate. The production and saponification of the copolymer of ethylene and a vinyl ester can be carried out by known methods. The saponification degree of the vinyl ester component of the ethylene-vinyl alcohol copolymer is preferably 90 mol% or more, more preferably 95 mol% or more, and even more preferably 99 mol% or more. By increasing the saponification degree to 90 mol% or more, gas barrier properties can be improved. The saponification degree of the ethylene-vinyl alcohol copolymer may be 100 mol% or less, or may be 99.99 mol% or less. The saponification degree of the ethylene-vinyl alcohol copolymer can be measured by nuclear magnetic resonance ( １ H-NMR measurement is performed to measure the peak area of ​​the hydrogen atoms contained in the vinyl ester structure and the peak area of ​​the hydrogen atoms contained in the vinyl alcohol structure.

[0019] When subjected to melt molding, the ethylene unit content of the ethylene-vinyl alcohol copolymer is preferably 10 mol% or more, more preferably 15 mol% or more, even more preferably 20 mol% or more, and even more preferably 25 mol% or more. Furthermore, the ethylene unit content of the ethylene-vinyl alcohol copolymer is preferably 65 mol% or less, more preferably 55 mol% or less, and even more preferably 50 mol% or less. When the ethylene unit content is 10 mol% or more, the gas barrier property and flex resistance tend to be maintained well under high humidity. On the other hand, when the ethylene unit content is 65 mol% or less, the gas barrier property can be improved. The ethylene unit content of the ethylene-vinyl alcohol copolymer can be determined by NMR.

[0020] On the other hand, when the vinyl alcohol polymer layer (A) is formed by coating a solution or dispersion, the ethylene unit content is preferably 50 mol% or less, more preferably 40 mol% or less. The solvent is not particularly limited, and may be water or an organic solvent such as alcohol. When an aqueous solution is prepared, the ethylene unit content is preferably 20 mol% or less, more preferably 15 mol% or less, and even more preferably 10 mol% or less. The ethylene unit content may be 0 mol% or more, or may be 1 mol% or more.

[0021] Furthermore, the vinyl alcohol polymer may contain units derived from other monomers other than ethylene, vinyl esters, and saponified products thereof, as long as the object of the present invention is not impaired. When the vinyl alcohol polymer contains the other monomer units, the content of the other monomer units relative to the total monomer units of the vinyl alcohol polymer is preferably 30 mol% or less, more preferably 20 mol% or less, even more preferably 10 mol% or less, and particularly preferably 5 mol% or less. When the vinyl alcohol polymer contains the units derived from the other monomers, the lower limit may be 0.05 mol% or 0.10 mol%. Examples of the other monomers include alkenes such as propylene, butylene, pentene, and hexene; 3-acyloxy-1-propene, 3-acyloxy-1-butene, 4-acyloxy-1-butene, 3,4-diacyloxy-1-butene, 3-acyloxy-4-methyl-1-butene, 4-acyloxy-2-methyl-1-butene, and 4-acyloxy-3-methyl- 1-butene, 3,4-diacyloxy-2-methyl-1-butene, 4-acyloxy-1-pentene, 5-acyloxy-1-pentene, 4,5-diacyloxy-1-pentene, 4-acyloxy-1-hexene, 5-acyloxy-1-hexene, 6-acyloxy-1-hexene, 5,6-diacyloxy-1-hexene, 1,3-diacetoxy-2-methylenepentene unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, or the like, or their anhydrides, salts, or mono- or dialkyl esters; nitriles such as acrylonitrile and methacrylonitrile; amides such as acrylamide and methacrylamide; olefin sulfonic acids such as vinyl sulfonic acid, allyl sulfonic acid, methallylsulfonic acid, or salts thereof; vinyl silane compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxyethoxy)silane, γ-methacryloxypropylmethoxysilane; alkyl vinyl ethers, vinyl ketone, N-vinylpyrrolidone, vinyl chloride, vinylidene chloride, and the like.

[0022] When the vinyl alcohol polymer is a blend of two or more different vinyl alcohol polymers, the average ethylene unit content or saponification degree of the entire vinyl alcohol polymer is defined as the ethylene unit content or saponification degree of the vinyl alcohol polymer.

[0023] The vinyl alcohol polymer preferably has an MFR (190°C, 2.16 kg load) of 0.5 g / 10 min or more and 12 g / 10 min or less, more preferably 1.0 g / 10 min or more and 8.0 g / 10 min or less. The vinyl alcohol polymer preferably has an average degree of polymerization of 200 or more and 5,000 or less.

[0024] The lower limit of the proportion of the vinyl alcohol-based polymer in the resin constituting the vinyl alcohol-based polymer layer (A) is preferably 70 mass%, more preferably 80 mass%, and even more preferably 90 mass%, from the viewpoint of gas barrier properties and the like, and may be 95 mass%, 99 mass%, 99.9 mass%, or 100 mass%.

[0025] The lower limit of the content of the vinyl alcohol polymer in the vinyl alcohol polymer layer (A) is preferably 70% by mass, more preferably 80% by mass, and even more preferably 90% by mass, and may be 95%, 99%, or 99.9% by mass, from the viewpoint of gas barrier properties, etc. The upper limit of the content of the vinyl alcohol polymer in the vinyl alcohol polymer layer (A) may be 100% by mass or 99.99% by mass.

[0026] The vinyl alcohol polymer layer (A) may contain inorganic oxide particles as needed. The inorganic oxide constituting the inorganic oxide particles is not particularly limited, but examples thereof include silicon oxide, aluminum oxide, magnesium oxide, zirconium oxide, cerium oxide, tungsten oxide, molybdenum oxide, and composites thereof. Among these, silicon oxide or silicon oxide-magnesium oxide is preferred, and silicon oxide is more preferred.

[0027] The lower limit of the content of inorganic oxide particles in the vinyl alcohol polymer layer (A) is preferably 0.001% by mass, more preferably 0.005% by mass, and even more preferably 0.01% by mass. The upper limit of the content of inorganic oxide particles is preferably 1% by mass, more preferably 0.7% by mass, and even more preferably 0.5% by mass. When the content of inorganic oxide particles is within the above range, the gas barrier property tends to be further improved.

[0028] The average particle size of the inorganic oxide particles is preferably 1 μm or more and 10 μm or less, and more preferably 2 μm or more and 5 μm or less. When the average particle size of the inorganic oxide particles is within the above range, the gas barrier property tends to be further improved. The average particle size of the inorganic oxide particles is the d50 value measured by a laser diffraction scattering method.

[0029] The vinyl alcohol-based polymer layer (A) may further contain a boron compound, a carboxylic acid, a phosphorus compound, a metal ion, an antioxidant, an ultraviolet absorber, a plasticizer, an antistatic agent, a lubricant, a colorant, a filler, a heat stabilizer, or the like, and may contain two or more of these optional components.

[0030] When the vinyl alcohol-based polymer layer (A) is formed by melt molding, the vinyl alcohol-based polymer layer (A) may be a non-stretched layer or a stretched layer. However, from the viewpoints of dimensional stability and gas barrier properties, a layer stretched at least uniaxially is preferred, and a layer stretched biaxially is more preferred. From the viewpoints of thickness uniformity, barrier properties, mechanical properties, and film-forming properties, the stretching ratio is preferably 2.5 to 4.5 times in the longitudinal direction (MD direction), 2.5 to 4.5 times in the transverse direction (TD direction), and 7 to 15 times in the areal stretching ratio, more preferably 2.5 to 3.5 times in the longitudinal direction, 2.5 to 3.5 times in the transverse direction, and 8 to 12 times in the areal stretching ratio. Such a stretching treatment method can be carried out according to a known method such as a commonly used simultaneous biaxial stretching or sequential biaxial stretching.

[0031] The thickness of the vinyl alcohol-based polymer layer (A) is not particularly limited, but is preferably 0.1 μm or more and 20 μm or less. A thickness of 0.1 μm or more of the vinyl alcohol-based polymer layer (A) improves the gas barrier properties of the vapor-deposited film. The thickness of the vinyl alcohol-based polymer layer (A) is more preferably 0.2 μm or more, and even more preferably 0.5 μm or more. The vinyl alcohol-based polymer layer (A) can also be formed by coating a vinyl alcohol-based polymer solution onto another resin. Alternatively, the vinyl alcohol-based polymer can be co-extruded with another resin to form a multilayer film, and the multilayer film can be stretched as needed to form the vinyl alcohol-based polymer layer (A). It is preferable to form a co-extruded multilayer film and stretch the multilayer film as needed. Furthermore, a thickness of 20 μm or less of the vinyl alcohol-based polymer layer (A) facilitates the recovery and reuse of the recovered multilayer structure by mixing it with a polyolefin and melt-kneading, resulting in excellent recyclability. The thickness of the vinyl alcohol polymer layer (A) is more preferably 10 μm or less, further preferably 8 μm or less, and particularly preferably 6 μm or less. The "thickness" refers to the average value of values ​​measured at any five points, and the same applies to the thicknesses of other layers described in this specification.

[0032] It is also preferable that the ratio of the thickness of the vinyl alcohol-based polymer layer (A) to the thickness of the multilayer structure is less than 25%. By being less than 25%, it becomes easy to mix the recovered multilayer structure with polyolefin, melt-knead it, and recover and reuse it, and the recyclability is excellent. The ratio of the thickness of the vinyl alcohol-based polymer layer (A) to the thickness of the multilayer structure is more preferably less than 20%, even more preferably less than 15%. When particularly good recyclability is required, it is more preferably less than 10%, even more preferably less than 5%.

[0033] The oxygen permeability of the vinyl alcohol polymer layer (A) is 50 mL 20 μm / (m ２ ·day·atm) or less, and 10mL·20μm / (m ２ ·day·atm) or less is more preferable, and 5 mL ·20 μm / (m ２·day·atm) or less is more preferable, and 1 mL·20 μm / (m ２ Here, the oxygen permeability is a value measured on a film having a thickness of 20 μm under conditions of 20° C. and 65% RH in accordance with the method described in ISO 14663-2 Annex C (1999).

[0034] (Vapor-Deposited Layer (B)) The vapor-deposited layer (B) made of silicon oxide or a metal oxide can be effectively formed, for example, by vacuum deposition. For example, when vacuum-depositing silicon oxide or a metal oxide onto a resin film that will become the vinyl alcohol-based polymer layer (A), it is important to perform the deposition while supplying an appropriate amount of oxygen gas toward the resin film. This results in the formation of a vapor-deposited layer (B) in which oxygen elements are segregated near the interface with the vinyl alcohol-based polymer layer (A). The degree of segregation can be controlled by, for example, the supply rate of oxygen gas sprayed onto the resin film. The supply rate of oxygen gas to the resin film is, for example, preferably 0.1 mL / min to 10 mL / min, more preferably 0.2 mL / min to 5 mL / min, and even more preferably 0.3 mL / min to 1 mL / min. However, the suitable supply rate of oxygen gas can be appropriately adjusted depending on conditions such as the deposition rate of silicon oxide or metal oxide. The vapor-deposited layer (B) in which oxygen elements are segregated may also be formed by a vapor deposition method other than those described above. For example, the vapor deposition layer (B) may be provided by sputtering, ion plating, ion beam mixing, plasma CVD, laser CVD, MO-CVD, thermal CVD, or the like.

[0035] Before vapor deposition, the surface of the vinyl alcohol polymer layer (A) to be vapor-deposited may be plasma-treated. The plasma treatment may be performed by a known method, and atmospheric pressure plasma treatment is preferred. Examples of discharge gases used in atmospheric pressure plasma treatment include nitrogen gas, helium, neon, argon, krypton, xenon, and radon.

[0036] Silicon oxide or metal oxide (MO Ｘ The vapor deposition layer (B) is made of silicon oxide (SiO Ｘ) or metal oxide. Here, M represents silicon or a metal element. The metal oxide is aluminum oxide (AlO Ｘ ), magnesium oxide, calcium oxide, titanium oxide, boron oxide, hafnium oxide, barium oxide, etc. Among these, a vapor deposition layer made of aluminum oxide or silicon oxide is preferred, and a vapor deposition layer made of silicon oxide is more preferred. Ｘ By providing the vapor-deposited layer (B) made of the above-mentioned fluororesin, the resulting vapor-deposited film (X) has excellent transparency and recyclability.

[0037] In the vapor-deposited film (X) of the present invention, when the surface of the vapor-deposited layer (B) on the ethylene-vinyl alcohol copolymer layer (A) side is designated as surface (b1) and the surface opposite to the vapor-deposited layer (B) is designated as surface (b2), and elemental analysis of the vapor-deposited layer (B) is performed in the depth direction from surface (b2) to surface (b1) using a scanning X-ray photoelectron spectrometer, the molar ratio (O / M) of oxygen element (O) to silicon element or metal element (M) in surface (b1) is ｂ１ and the molar ratio (O / M) of oxygen element (O) to silicon element or metal element (M) at positions equidistant from the surface (b1) and the surface (b2). ｃ The ratio [(O / M) ｂ１ / (O / M) ｃ The most notable feature is that the value of [Ratio of Ratio of ] is 1.1 or more and 1.7 or less.

[0038] Hereinafter, with reference to FIGS. 1 to 4, elemental analysis of the vapor-deposited layer (B) in the depth direction using a scanning X-ray photoelectron spectrometer will be described. FIG. 1 is a graph plotting the molar ratios of silicon (Si), oxygen (O), and carbon (C) (total 100 mol%) versus sputtering time when the vapor-deposited layer (B) described in Example 2 was analyzed using a scanning X-ray photoelectron spectrometer. FIG. 2 is a graph plotting the molar ratio (O / Si) calculated from FIG. 1 versus sputtering time. The sputtering time of 0 minutes corresponds to the outermost surface of the vapor-deposited layer (B) and corresponds to surface (b2). Near surface (b2) exposed to the outside air, C and O increase due to the adsorption and oxidation of organic substances. Meanwhile, the composition of the vapor-deposited layer (B) near surface (b1) in contact with the vinyl alcohol-based polymer layer (A) also becomes unstable due to the influence of the vinyl alcohol-based polymer layer (A). Therefore, the molar ratio (O / M) at positions (centers) equidistant from surfaces (b1) and (b2) ｃ was adopted as the reference value. Since the etching rate of the vapor-deposited layer (B) is considered to be nearly constant, the "position equidistant from surface (b1) and surface (b2)" corresponds to half of the sputtering time of surface (b1). Surface (b1) corresponds to the time when the proportion of carbon elements derived from the vinyl alcohol-based polymer layer (A) reaches 1 mol %, indicating the point at which the influence of the substrate begins. The vapor-deposited film described in Example 2 was characterized by an increase in the oxygen concentration in the vapor-deposited layer (B) near surface (b1) because the film was formed while oxygen was supplied near the surface of the vinyl alcohol-based polymer layer (A) of the substrate.

[0039] The ratio calculated in this way [(O / M) ｂ１ / (O / M) ｃ When the ratio [(O / M) ｂ１ / (O / M) ｃ] is large means that the oxygen content in the vapor-deposited layer (B) is high near the interface between the vinyl alcohol-based polymer layer (A) and the vapor-deposited layer (B), which is presumably to improve the adhesion between the vinyl alcohol-based polymer layer (A) and the vapor-deposited layer (B) and make the gas barrier property less likely to decrease even after bending treatment. As will be shown in the examples below, when the film substrate is polyester or polyamide, the ratio [(O / M) ｂ１ / (O / M) ｃ The ratio [(O / M)] was less than 1.1, and the gas barrier properties after bending treatment were insufficient. This suggests that the state of oxygen present near the interface with the substrate changes depending on the substrate, and the oxidation degree of the vapor-deposited layer (B) changes. ｂ１ / (O / M) ｃ ] is preferably 1.13 or more, more preferably 1.15 or more. ｂ１ / (O / M) ｃ When the ratio [(O / M) ] is 1.7 or less, the vapor deposition layer (B) can suppress a decrease in gas barrier properties after a storage test. ｂ１ / (O / M) ｃ ] is preferably 1.5 or less, more preferably 1.3 or less.

[0040] The molar ratio (O / M) of oxygen element (O) to silicon element or metal element (M) in the surface (b1) ｂ１ The molar ratio (O / M) is preferably 1.85 or more and 2.35 or less. ｂ１ When the molar ratio (O / M) is 1.85 or more, the adhesion between the vapor-deposited layer (B) and the vinyl alcohol-based polymer layer (A) is improved, and a decrease in the gas barrier property after bending treatment can be suppressed. ｂ１ is more preferably 1.95 or more, even more preferably 2.0 or more, and particularly preferably 2.05 or more. ｂ１ When the molar ratio (O / M) is 2.35 or less, a homogeneous vapor-deposited layer (B) can be formed. ｂ１ is more preferably 2.3 or less.

[0041] In addition, the molar ratio (O / M) of oxygen element (O) to silicon element or metal element (M) at positions equidistant from the surface (b1) and the surface (b2) is ｃ The molar ratio (O / M) is preferably 1.5 or more and 2.0 or less. ｃ When the molar ratio (O / M) is 1.5 or more, the vapor deposition layer (B) can suppress a decrease in gas barrier properties after a storage test. ｃ is more preferably 1.55 or more, even more preferably 1.6 or more, and particularly preferably 1.65 or more, and in some cases 1.80 or more is preferable, and in other cases 1.81 or more is preferable. ｃ is 2.0 or less, (O / M) ｂ１ It becomes easier to increase the difference between the molar ratio (O / M) and the ｃ is more preferably 1.95 or less, and even more preferably 1.9 or less.

[0042] The thickness of the vapor-deposited layer (B) is 30 nm or more and 200 nm or less. The lower limit of the thickness of the vapor-deposited layer (B) is preferably 40 nm, more preferably 50 nm. When the thickness of the vapor-deposited layer (B) is equal to or greater than the above lower limit, the gas barrier properties and flex resistance of the vapor-deposited film can be further improved. The upper limit of the thickness of the vapor-deposited layer (B) is preferably 180 nm, and may be 160 nm or 140 nm.

[0043] The thickness of the vapor-deposited film (X) of the present invention is not particularly limited, and the lower limit may be, for example, 5 μm, 8 μm, or 10 μm, while the upper limit may be, for example, 100 μm, 50 μm, 30 μm, or 20 μm.

[0044] The oxygen permeability of the vapor-deposited film (X) of the present invention is 1.0 mL / (m ２ ·day·atm), and preferably less than 0.10 mL / (m ２ ·day·atm), and more preferably less than 0.08 mL / (m ２ ·day·atm), and more preferably less than 0.05 mL / (m ２It is particularly preferable that the oxygen permeability is less than the above upper limit, so that the material can be particularly suitably used as various packaging materials. On the other hand, the lower limit of the oxygen permeability is 0 mL / (m ２ ·day·atm), and 0.001 mL / (m ２ The oxygen permeability of the vapor-deposited film (X) is a value measured under conditions of 20°C and 65% RH in accordance with the method described in ISO 14663-2 Annex C (1999).

[0045] In a preferred embodiment, the vapor-deposited film (X) comprises, in this order, a polyolefin substrate layer (G), a polyolefin-based adhesive layer (H), a vinyl alcohol-based polymer layer (A), and a vapor-deposited layer (B). These layers are in direct contact with each other. The polyolefin substrate layer (G), the polyolefin-based adhesive layer (H), and the vinyl alcohol-based polymer layer (A) are preferably coextruded. Coextrusion improves productivity and facilitates thinning of the vinyl alcohol-based polymer layer (A). The polyolefin substrate layer (G), the polyolefin-based adhesive layer (H), and the vinyl alcohol-based polymer layer (A) are preferably stretched at least uniaxially. More preferably, they are biaxially stretched. The stretching ratio and stretching conditions are as described above for the vinyl alcohol-based polymer layer (A). This allows the vinyl alcohol-based polymer layer (A) to be further thinned and improves its elastic modulus.

[0046] When the polyolefin substrate layer (G), the polyolefin adhesive layer (H), and the vinyl alcohol polymer layer (A) are co-extrusion molded, it is preferable that the vinyl alcohol polymer layer (A) contains, as a main component, an ethylene-vinyl alcohol copolymer having an ethylene unit content of 10 to 65 mol% and a saponification degree of 90 mol% or more. An ethylene unit content of 10 mol% or more improves melt moldability. The ethylene unit content is more preferably 15 mol% or more, even more preferably 20 mol% or more, and particularly preferably 25 mol% or more. On the other hand, an ethylene content of 65 mol% or less improves gas barrier properties. The ethylene unit content is more preferably 60 mol% or less, even more preferably 55 mol% or less, and particularly preferably 50 mol% or less. Furthermore, a saponification degree of 90 mol% or more improves melt stability. The saponification degree is more preferably 95 mol% or more, even more preferably 98 mol% or more, and particularly preferably 99 mol% or more.

[0047] In another preferred embodiment, the vapor-deposited film (X) has a polyolefin substrate layer (G), a vinyl alcohol-based polymer layer (A), and a vapor-deposited layer (B) in this order. In this case, these layers may be in direct contact with each other or may be contacted via an adhesive layer. The vinyl alcohol-based polymer layer (A) is preferably formed by coating a solution or dispersion of a vinyl alcohol-based polymer onto the polyolefin substrate layer (G). This makes it easy to thin the vinyl alcohol-based polymer layer (A). Preferred solvents for the solution include alcohol, water, or a mixture thereof. Examples of alcohol include methanol, ethanol, 1-propanol, and 2-propanol. Preferred dispersion media for the dispersion are water.

[0048] When a vinyl alcohol polymer layer (A) is formed by coating a solution or dispersion of a vinyl alcohol polymer on a polyolefin substrate layer (G), it is preferable that the vinyl alcohol polymer layer (A) contains, as a main component, a vinyl alcohol polymer having an ethylene unit content of 50 mol% or less and a saponification degree of 70 mol% or more. An ethylene unit content of 50 mol% or less improves solubility in solvents. In this case, the ethylene unit content is more preferably 40 mol% or less. When dissolved in water or a water / alcohol mixed solvent, the ethylene unit content is more preferably 20 mol% or less, even more preferably 15 mol% or less, and particularly preferably 10 mol% or less. The ethylene unit content may be 0 mol%, but from the viewpoint of water solubility, it may be 1 mol% or more.

[0049] The vapor-deposited film (X) of the present invention has excellent gas barrier properties and flex resistance. Furthermore, the vapor-deposited film (X) can suppress deterioration of the gas barrier properties after a storage test. Therefore, the vapor-deposited film (X) can be used in a variety of applications. Examples of applications of the vapor-deposited film (X) include various packaging materials such as food packaging, pharmaceutical packaging, industrial chemical packaging, and pesticide packaging, as well as vacuum packaging bags and vacuum insulators.

[0050] <Multilayer structure> The multilayer structure of the present invention is a multilayer structure formed by laminating a vapor-deposited film (X) and a polyolefin layer (C). The thickness of the polyolefin-based layer accounts for 75% or more of the total thickness of the multilayer structure. A high polyolefin content contributes to excellent recyclability. The thickness of the polyolefin-based layer is preferably 85% or more, more preferably 90% or more, and particularly preferably 95% or more. Here, the polyolefin-based layer may refer to not only the "polyolefin layer (C)," but also any layer containing a resin with an olefin unit content of 25 mol% or more as the main component, such as a "polyolefin substrate layer (G)," a "polyolefin-based adhesive layer (H)," or an EVOH layer with an ethylene unit content of 25 mol% or more. From the viewpoint of better recyclability, a layer containing a resin with an olefin unit content of 50 mol% or more as the main component may be used as the polyolefin-based layer.

[0051] (Polyolefin Layer (C)) The multilayer structure of the present invention is a multilayer structure obtained by laminating the vapor-deposited film (X) of the present invention and a polyolefin layer (C). That is, the multilayer structure comprises a vapor-deposited film (X) and a polyolefin layer (C) laminated on at least one surface of the vapor-deposited film (X) directly or via another layer. When the multilayer structure comprises the vapor-deposited film (X) and the polyolefin layer (C), it is possible to improve not only the gas barrier property but also the water vapor barrier property. Furthermore, when the polyolefin layer (C) is the outermost layer of the multilayer structure, it can be easily molded into a shape such as a bag by, for example, heat-sealing the polyolefin layer (C) as a heat-sealing layer. In the multilayer structure of the present invention, the polyolefin layer (C) may be the innermost layer when formed into a bag.

[0052] The polyolefin layer (C) may be laminated directly to the vapor-deposited film (X) of the present invention, or may be laminated via another layer. Examples of the other layer include an adhesive layer. Examples of the adhesive layer include a layer made of a curing adhesive (such as a two-component reactive polyurethane adhesive).

[0053] The polyolefin constituting the polyolefin layer (C) is preferably polyethylene or polypropylene.

[0054] The polyolefin layer (C) may be a non-stretched layer or a stretched layer. In the multilayer structure of the present invention, when the multilayer structure is formed into a bag shape and the innermost layer is the polyolefin layer (C), it is preferred that the innermost polyolefin layer (C) is a non-stretched layer from the viewpoint of good heat sealability.

[0055] The lower limit of the thickness of the polyolefin layer (C) is preferably 5 μm, more preferably 10 μm, and even more preferably 15 μm, and may be 20 μm, 30 μm, or 40 μm. When the thickness of the polyolefin layer (C) is equal to or greater than the above lower limit, sufficient moisture resistance can be exhibited. Furthermore, when the polyolefin layer (C) is the outermost layer, when the thickness of the polyolefin layer (C) is equal to or greater than the above lower limit, sufficient heat sealability can also be exhibited. The upper limit of the thickness of the polyolefin layer (C) is preferably 200 μm, more preferably 100 μm, and may be 60 μm or 40 μm. When the thickness of the polyolefin layer (C) is equal to or less than the above upper limit, the thickness of the multilayer structure can be reduced.

[0056] The polyolefin content in the polyolefin layer (C) is preferably 80% by mass or more and 100% by mass or less, more preferably 90% by mass or more and 100% by mass or less, and even more preferably 97% by mass or more and 100% by mass or less. The polyolefin layer (C) may contain, as components other than polyolefin, antioxidants, ultraviolet absorbers, plasticizers, antistatic agents, lubricants, colorants, fillers, heat stabilizers, resins other than polyolefins, and the like.

[0057] The polyolefin layer (C) may consist of a single layer or multiple layers. It is also preferable to have multiple polyolefin layers (C), one of which is a non-oriented polyolefin layer and the other is a oriented polyolefin layer. The non-oriented polyolefin layer has good heat-sealing properties when used as a sealant layer. The oriented polyolefin layer has excellent rigidity and water vapor barrier properties.

[0058] The multilayer structure of the present invention preferably does not contain a layer containing a resin having a melting point of 200°C or higher as a main component or a metal layer having a thickness of 1 μm or more. If such a layer is contained, melt-kneading at low temperatures becomes difficult when the multilayer structure is recovered and melt-kneaded, making it difficult to recycle the multilayer structure together with polyolefins. Therefore, it is preferable that the multilayer structure of the present invention does not contain a polyester layer, a polyamide layer, an aluminum foil, or the like.

[0059] (Another vapor-deposited film (Y)) The multilayer structure of the present invention may further comprise another vapor-deposited film (Y) laminated directly or via another layer on the vapor-deposited film (X) of the present invention. In other words, the multilayer structure of the present invention may comprise a plurality of vapor-deposited films, and at least one of the plurality of vapor-deposited films may be the vapor-deposited film (X) of the present invention. A preferred example of the vapor-deposited film (Y) is a vapor-deposited film (Y) comprising a polyolefin layer and a vapor-deposited layer (E) made of silicon oxide or a metal oxide. Here, a biaxially oriented polypropylene layer is preferred as the polyolefin layer. The vapor-deposited layer (E) may be formed as a silicon oxide or aluminum oxide layer with a thickness similar to that of the vapor-deposited layer (B). A multilayer structure comprising a plurality of vapor-deposited films has superior gas barrier properties. The plurality of vapor-deposited films may be laminated directly to each other or may be laminated via another layer. The other layer is preferably an adhesive layer. Multiple layers may be present between the multiple vapor-deposited films.

[0060] When the multilayer structure of the present invention has an adhesive layer, the thickness of the adhesive layer is, for example, preferably 0.1 μm or more and 10 μm or less, more preferably 0.3 μm or more and 7 μm or less, and even more preferably 0.5 μm or more and 5 μm or less. By setting the thickness of the adhesive layer within the above range, it is possible to achieve a reduction in the weight of the multilayer structure while exhibiting sufficient adhesiveness. As the adhesive, a polyurethane-based adhesive is suitable.

[0061] (Layer Structure) Examples of the layer structure of the multilayer structure of the present invention include: (1) vinyl alcohol polymer layer (A) / vapor-deposited layer (B) / / polyolefin layer (C) (2) C / / A / B / / C (3) polyolefin substrate layer (G) / A / B / / C (4) C / / G / A / B / / C (5) G / polyolefin adhesive layer (H) / A / B / / C (6) C / / G / H / A / B / / C and the like.

[0062] The lower limit of the thickness of the multilayer structure of the present invention (the thickness of the entire multilayer structure) is preferably 10 μm, and may be 20 μm, 30 μm, or 50 μm. When the thickness of the multilayer structure is equal to or greater than the above lower limit, the gas barrier property and flex resistance can be further improved. The upper limit of the thickness of the multilayer structure is preferably 1,000 μm, and may be 500 μm, 300 μm, 200 μm, or 100 μm.

[0063] The method for producing the multilayer structure of the present invention is not particularly limited. For example, the multilayer structure can be obtained by laminating a film of the polyolefin layer (C) or the like onto the vapor-deposited film (X) of the present invention by a known means such as dry lamination.

[0064] The multilayer structure of the present invention can be used for various packaging materials such as food packaging, pharmaceutical packaging, industrial chemical packaging, and agricultural chemical packaging.

[0065] <Packaging Material> The packaging material of the present invention includes the multilayer structure of the present invention. The packaging material is used for packaging purposes, and its shape is not limited. The packaging material may be in the form of a sheet, or may be molded into a predetermined shape such as a bag. From the viewpoint of heat sealing properties, etc., it is preferable that the polyolefin layer (C) is located in the outermost layer as a heat-sealable layer. Also, from the viewpoint of heat sealing properties, etc., it is preferable that the polyolefin layer (C) located in the outermost layer is not stretched. In the case of a packaging material molded into a shape having an inside and an outside, such as a bag, it is preferable that the polyolefin layer (C) is located at least in the innermost layer. Also, it is preferable that the vapor-deposited layer (B) is located outside the vinyl alcohol-based polymer layer (A).

[0066] The packaging material of the present invention is used for packaging, for example, food, beverages, medicines, medical equipment, machine parts, clothing, etc. In particular, the packaging material is preferably used in applications requiring oxygen barrier properties and applications in which the interior of the packaging material is replaced with various functional gases. Because the packaging material includes the vapor-deposited film (X) of the present invention, deterioration of gas barrier properties after bending treatment is suppressed, and high gas barrier properties can be maintained over a long period of time. Furthermore, the packaging material is suitable as a packaging material for containing contents containing 5% or more by weight of moisture and at least one selected from the group consisting of 1% or more by weight of lipids, 1% or more by weight of sodium chloride, and 0.5% or more by weight of acetic acid. The packaging material of the present invention is less likely to deteriorate in gas barrier properties even when containing such high-moisture foods.

[0067] The packaging material is formed into various forms depending on the application, such as vertical form-fill-seal bags, spouted pouches, laminated tube containers, container lids, vacuum packaging bags, and the like.

[0068] Vertical form, fill, and seal pouches are used to package, for example, liquids, viscous materials, powders, bulk solids, and combinations of these foods and beverages. Vertical form, fill, and seal pouches are formed by heat-sealing a multilayer structure. When heat-sealing is performed, it is usually necessary to provide a heat-sealable layer (e.g., polyolefin layer (C)) on the layer of the multilayer structure that will become the inner layer of the vertical form, fill, and seal pouch, or on both the inner and outer layers of the vertical form, fill, and seal pouch. When the heat-sealable layer is only on the inner side of the vertical form, fill, and seal pouch, the body is usually sealed by seaming. When the heat-sealable layer is on both the inner and outer sides of the vertical form, fill, and seal pouch, the body is usually sealed by enveloping.

[0069] Spouted pouches are used to package liquid substances, such as liquid beverages such as soft drinks, jelly drinks, yogurt, fruit sauces, seasonings, functional water, liquid diets, etc. Laminated tube containers are used to package cosmetics, medicines, pharmaceuticals, food, toothpaste, etc. Container lids are lids for containers filled with foods such as processed meat products, processed vegetables, processed seafood products, and fruits.

[0070] A vacuum packaging bag includes a packaging bag formed from the packaging material of the present invention, and the interior of the packaging bag is reduced in pressure. The vacuum bag is used for applications where packaging in a vacuum state is desired, such as preserving food, beverages, etc., and as an outer packaging material for vacuum insulators. Since such a vacuum packaging bag includes the vapor-deposited film (X) of the present invention, deterioration of gas barrier properties after bending treatment is suppressed, and a high vacuum state can be maintained for a long period of time. A multilayer structure suitable for use in a vacuum packaging bag preferably includes multiple vapor-deposited films (X).

[0071] The present invention will be described in more detail below with reference to examples, but is not limited to these examples. In the examples, " / " indicates that the two layers sandwiching the " / " are directly laminated together, and " / / " indicates that the two layers sandwiching the " / / " are laminated together via an adhesive.

[0072] [Materials used in Examples and Comparative Examples] (Vinyl alcohol polymers) EVOH-1: ethylene-vinyl alcohol copolymer pellets (ethylene unit content 48 mol%, saponification degree 99.9 mol%, MFR (190°C, 2.16 kg load) 6.4 g / 10 min, melting point 157°C) EVOH-2: ethylene-vinyl alcohol copolymer pellets (ethylene unit content 32 mol%, saponification degree 99.9 mol%, MFR (190°C, 2.16 kg load) 1.6 g / 10 min, melting point 183°C) EVOH-3: ethylene-vinyl alcohol copolymer pellets (ethylene unit content 3 mol%, saponification degree 99.3 mol%, polymerization degree 1700) PVOH-1: polyvinyl alcohol resin (saponification degree 98.5 mol%, polymerization degree 1700) (Polyolefins) PP1: "Novatec (trademark) PP" EA7AD (Japan Polypropylene Corporation, polypropylene, MFR (230°C, 2.16 kg load) 1.4 g / 10 min, density 0.90 g / cm ３ PE1: "INNATE (trademark) TF80" (manufactured by DOW, linear low-density polyethylene, MFR (190 ° C, 2.16 kg load) 1.6 g / 10 min, melting point 124 ° C, density 0.926 g / cm ３ ) MAhPP1: "ADMER (trademark) QF500" (manufactured by Mitsui Chemicals, Inc., maleic anhydride modified polypropylene, MFR (230°C, 2.16 kg load) 3.0 g / 10 min) MAhPP2: "ADMER (trademark) SF730" (manufactured by Mitsui Chemicals, Inc., maleic anhydride modified polyolefin, MFR (190°C, 2.16 kg load) 2.7 g / 10 min) MAhPE1: ADMER (trademark) NF518" (manufactured by Mitsui Chemicals, Inc., maleic anhydride modified polyethylene, MFR (190°C, 2.16 kg load) 3.1 g / 10 min, melting point 121°C, density 0.91 g / cm ３, acid value 1.8 mgKOH / g) BOPP: "Pylen (trademark) Film-OT P2161" (Toyobo Co., Ltd., biaxially oriented polypropylene film, thickness 20 μm) CPP: "RXC-22" (Mitsui Chemicals Tohcello Co., Ltd., unstretched polypropylene film, thickness 50 μm) LLDPE: "Unilux (registered trademark) LS760C" (Idemitsu Unitech Co., Ltd., unstretched linear low-density polyethylene film, thickness 50 μm) (Other resins) ADh1: "Takelac (registered trademark) A-520" (Mitsui Chemicals, Inc., two-component polyurethane adhesive polyol component) ADh2: "Takenate (registered trademark) A-50" (Mitsui Chemicals, Inc., two-component polyurethane adhesive isocyanate component) ADh3: "Takelac (registered trademark) A-626" (Mitsui Chemicals, Inc., two-component polyurethane adhesive polyol component) PET: "TRN-RTJ" (manufactured by Teijin Limited) PA: "UBE Nylon (trademark) SF1018A" (manufactured by Ube Industries, Ltd.)

[0073] [Evaluation Method] (1) Molar Ratio (O / M) of Vapor Deposited Layer (B) The vapor deposited layer (B) of the vapor deposited film (X), which was made of silicon oxide or metal oxide, was subjected to elemental analysis while sputtering in the depth direction (from the surface (b2) side to the surface (b1) side) using a scanning X-ray photoelectron spectrometer "PHI Quntera SXM" manufactured by ULVAC-PHI, Inc. The X-ray source was AlKα (1486.6 eV), the X-ray beam diameter was 100 μmφ (25 W, 15 kV), the measurement range was 300 μm horizontal × 300 μm vertical, the signal acquisition angle was 45°, and the vacuum degree was 1×10 -６ The measurement was carried out under the condition of 100 Pa. The molar ratio of oxygen element (O) to silicon element or metal element (M) on the surface (b1) was (O / M). ｂ１ The molar ratio of oxygen element (O) to silicon element or metal element (M) at a position equidistant from the surface (b1) and the surface (b2) is (O / M). ｃ and the ratio [(O / M) ｂ１ / (O / M) ｃHere, the surface (b2) is the position where sputtering was started, the surface (b1) is the position where the content of carbon derived from the EVOH layer (A) reached 1 mol %, and a position equidistant from the surface (b1) and the surface (b2) was determined as the midpoint of the etching time.

[0074] (2) Oxygen Transmission Rate (OTR) The oxygen transmission rate of the multilayer structures obtained in the examples and comparative examples was measured in accordance with the method described in JIS K 7126-2 (isobaric method; 2006). Specifically, the oxygen transmission rate (unit: cc / (m)) was measured using an oxygen transmission rate measuring device ("MOCON OX-TRAN2 / 21" manufactured by Modern Control) under the conditions of a temperature of 20°C, a humidity of 65% RH on the oxygen supply side, a humidity of 65% RH on the carrier gas side, an oxygen pressure of 1 atmosphere, and a carrier gas pressure of 1 atmosphere. ２ The oxygen gas pressure (ppm / day / atm) was measured. Nitrogen gas containing 2% by volume of hydrogen gas was used as the carrier gas. The outer layer was the oxygen supply side, and the inner layer (sealant layer side) was the carrier gas side.

[0075] (3) OTR after storage test Two sheets of A4 size (210 mm x 297 mm) were cut out from the multilayer structures obtained in the Examples and Comparative Examples, and then the sheets were placed together with the insides facing each other (sealant layers facing each other), and three sides were heat-sealed to produce a three-sided bag. 50 g of mayonnaise was filled into the three-sided bag, and the opening was heat-sealed at 150°C to produce a pouch (packaged body) filled with the contents. The resulting package was stored for 30 days under conditions of 34°C and 78% RH, and then opened. The mayonnaise was removed and washed with water, and the OTR was measured using the method described in the above evaluation method (2).

[0076] (4) Oxygen Transmission Rate (OTR) of Vapor-Deposited Films After Bending Test A 20 cm × 25 cm sample was cut from the vapor-deposited films obtained in the Examples and Comparative Examples, and a Gelbo Flex test (bending test) was performed in accordance with ASTM F 392 using a Gelbo Flex Tester (BE-1005) manufactured by Tester Sangyo Co., Ltd. Specifically, the cut-out vapor-deposited film was formed into a cylindrical shape with a diameter of 3.5 inches in an atmosphere of 23°C and 50% RH, and both ends were fixed to the Gelbo Flex Tester. The sample was subjected to three cycles of reciprocating motion, with an initial spacing of 7 inches, a maximum bending spacing of 1 inch, a 440° twist in the first 3.5 inches of the stroke, and a linear horizontal motion for the subsequent 2.5 inches. A portion of the bent portion of the vapor-deposited film after the bending test was cut out, and the oxygen transmission rate was measured according to the method described in the evaluation method (2) above.

[0077] Example 1 Using EVOH-1 as the material for the vinyl alcohol copolymer layer (A), MAhPP1 as the material for the polyolefin adhesive layer (H), and PP1 as the material for the polyolefin substrate layer (G), a three-kind, three-layer multilayer film (vinyl alcohol copolymer layer (A) / polyolefin adhesive layer (H) / polyolefin substrate layer (G) = 50 μm / 50 μm / 500 μm) was produced using a coextrusion film-forming device. The thickness of the multilayer film was adjusted by appropriately changing the screw rotation speed and take-up roll speed. The extruder, extrusion conditions, and die used were as follows: Vinyl alcohol copolymer layer (A) Extruder: Single-screw extruder (Toyo Seiki Co., Ltd., Laboratory machine ME type CO-EXT) Screw: Diameter 20 mmφ, L / D 20, Full-flight screw Extrusion temperature: Feeding section / Compression section / Metering section / Die = 175 / 220 / 220 / 220 ° C. Polyolefin adhesive layer (H) Extruder: Single-screw extruder (Technovel Co., Ltd., SZW20GT-20MG-STD) Screw: Diameter 20 mmφ, L / D 20, Full-flight screw Extrusion temperature: Feeding section / Compression section / Metering section / Die = 150 / 200 / 220 / 230 ° C. Polyolefin base layer (G) Extruder: Single-screw extruder (Plastics Technology Research Institute Co., Ltd., GT-32-A) Screw: Diameter 32 mmφ, L / D 28, Full-flight screw Extrusion temperature: feeding section / compression section / metering section / die = 170 / 220 / 230 / 230°C Die: 300mm wide, 3-type, 3-layer coat hanger die (manufactured by Plastics Engineering Research Institute) Die temperature: 230°C

[0078] The obtained multilayer film was stretched 5 times in the longitudinal direction and then 5 times in the transverse direction at 150°C using a tenter-type sequential biaxial stretching apparatus, to obtain a three-kind, three-layer biaxially oriented multilayer film (vinyl alcohol-based copolymer layer (A) / polyolefin-based adhesive layer (H) / polyolefin base layer (G)=2 μm / 2 μm / 20 μm).

[0079] On the surface of the vinyl alcohol copolymer layer (A) of the obtained biaxially stretched multilayer film, a vapor deposition layer (B) made of silicon oxide was formed by the following method using a winding-type vacuum vapor deposition apparatus "EWA-105" manufactured by Japan Vacuum Engineering Co., Ltd., which has a transfer chamber and a vapor deposition chamber. The "EWA-105" has an unwinder and a winder on the transfer chamber side, and silicon oxide (SiO Ｘ The chamber contained a crucible for heating the EVOH-1 film and a cooling can for cooling the film while transporting it, and the film was transported along the cooling can. The cooling can was cooled to -30°C, and a 20 cm wide EVOH-1 film was transported at a transport speed of 150 m / min. Furthermore, a nozzle for directly spraying oxygen onto the EVOH-1 before deposition was installed in the deposition chamber (nozzle gap 2 mm, film-nozzle distance 2 cm, angle to the film 30 degrees). Silicon oxide was vacuum-deposited while spraying oxygen at a rate of 0.38 mL / min, producing a deposited film in which a 40 nm-thick SiOx deposited layer (deposited layer (B)) was formed on the EVOH-1. The thickness of the deposited layer (B) was adjusted by appropriately controlling the voltage applied to the crucible. A portion was cut out from the obtained deposited film and evaluated according to the method described in Evaluation Method (1) above. The results are shown in Table 1.

[0080] An adhesive solution was prepared by mixing 24 parts by weight of a two-component reactive polyurethane adhesive (24 parts by weight of "Takelac™ A-520" and 4 parts by weight of "Takenate™ A-50" manufactured by Mitsui Chemicals, Inc.) with 37 parts by weight of ethyl acetate. The adhesive solution was applied to the vapor-deposited surface of the obtained vapor-deposited film using a wire bar so that the thickness after drying would be 2 μm, and then dried at 100°C for 5 minutes. This was then laminated to the corona-treated side of the CPP to form a polyolefin layer (C) as a sealant layer, producing a multilayer structure having a layer thickness and layer structure of polyolefin substrate layer (G) / polyolefin adhesive layer (H) / vinyl alcohol-based polymer layer (A) / vapor-deposited layer (B) / polyurethane adhesive layer / sealant layer = 20 μm / 2 μm / 2 μm / 40 nm / 2 μm / 50 μm. The adhesion temperature (heating roll temperature) during lamination was 80°C, and after the multilayer structure was produced, it was aged at 40°C for 3 days. The obtained multilayer structure was evaluated according to the above evaluation methods (2) to (4). The results are shown in Table 1.

[0081] Examples 2 to 5, Comparative Example 1 Vapor-deposited films and multilayer structures were prepared and evaluated in the same manner as in Example 1, except that the conveying speed of the biaxially stretched multilayer film during vapor deposition was changed so that the thickness of the vapor-deposited layer (B) made of silicon oxide was 60 nm (Example 2), 80 nm (Example 3), 100 nm (Example 4), 120 nm (Example 5), or 20 nm (Comparative Example 1). The results are shown in Table 1.

[0082] A vapor-deposited layer (B) formed on a biaxially stretched ethylene-vinyl alcohol copolymer film (ethylene unit content 32 mol%, saponification degree 99.9 mol%, thickness 12 μm) under the same conditions as in Example 2 was analyzed with a scanning X-ray photoelectron spectrometer. The molar ratios of silicon (Si), oxygen (O), and carbon (C) (total 100 mol%) were plotted against sputtering time in FIG. 1, and the molar ratio (O / Si) at that time was plotted against sputtering time in FIG. 2. Carbon derived from organic contamination on the vapor-deposited film surface was detected on surface (b2) at the start of sputtering, but carbon was no longer detected after etching proceeded for about 0.5 minutes. As etching proceeded, carbon derived from the EVOH layer (A) of the substrate began to be detected, and at 6.01 minutes when the carbon content reached 1 mol%, surface (b1) was reached, and the molar ratio of oxygen element to silicon element (O / Si) at this time was ｂ１ In addition, at a sputtering time of 3.005 minutes, the molar ratio of oxygen element (O) to silicon element (Si) (O / Si) at positions equidistant from the surface (b1) and the surface (b2) was ｃ The ratio [(O / Si) ｂ１ / (O / Si) ｃ ] was 1.17, which indicated that the molar ratio (O / Si) was higher near the interface with the EVOH layer (A) than at the center of the vapor-deposited layer (B).

[0083] Example 6 Using the same materials and the same co-extrusion film-forming apparatus as in Example 1, a three-kind, three-layer multilayer film (vinyl alcohol-based copolymer layer (A) / polyolefin-based adhesive layer (H) / polyolefin substrate layer (G) = 10 μm / 10 μm / 100 μm) was formed by adjusting the screw rotation speed and take-up roll speed. A vapor-deposited film and a multilayer structure were then produced and evaluated in the same manner as in Example 4, without subsequent stretching. The results are shown in Table 1.

[0084] Example 7 A deposited film and a multilayer structure were prepared and evaluated in the same manner as in Example 2, except that the supply rate of oxygen blown during deposition was changed to 0.19 mL / min. The results are shown in Table 1.

[0085] Example 8 A deposited film was prepared and evaluated in the same manner as in Example 2, except that the supply rate of oxygen blown during deposition was changed to 0.78 mL / min. The results are shown in Table 1.

[0086] Example 9 Using EVOH-2 as the material for the vinyl alcohol-based polymer layer (A), MAhPE1 as the material for the polyolefin-based adhesive layer (H), and PE1 as the material for the polyolefin base layer (G), a three-kind, three-layer multilayer film (thickness of vinyl alcohol-based copolymer layer (A) / polyolefin-based adhesive layer (H) / polyolefin base layer (G) = 20 μm / 20 μm / 200 μm) was produced using a coextrusion film-forming device. The thickness of the multilayer film was adjusted by appropriately changing the screw rotation speed and take-up roll speed. The extruder, extrusion conditions, and die used were as follows. Vinyl alcohol polymer layer (A) Extruder: Single-screw extruder (Toyo Seiki Co., Ltd., Laboratory machine ME type CO-EXT) Screw: Diameter 20 mmφ, L / D 20, Full-flight screw Extrusion temperature: Feeding section / Compression section / Metering section / Die = 175 / 220 / 220 / 220 ° C. Polyolefin adhesive layer (H) Extruder: Single-screw extruder (Technovel Co., Ltd., SZW20GT-20MG-STD) Screw: Diameter 20 mmφ, L / D 20, Full-flight screw Extrusion temperature: Feeding section / Compression section / Metering section / Die = 175 / 220 / 220 / 220 ° C. Polyolefin base layer (G) Extruder: Single-screw extruder (Plastics Technology Research Institute Co., Ltd., GT-32-A) Screw: Diameter 32 mmφ, L / D 28, Full-flight screw Extrusion temperature: feeding section / compression section / metering section / die = 175 / 220 / 230 / 220°C Die: 300mm wide, 3-type, 3-layer coat hanger die (manufactured by Plastics Engineering Research Institute) Die temperature: 220°C

[0087] The obtained multilayer film was stretched 5 times in the longitudinal direction at 120°C using a uniaxial stretching device to obtain a three-kind, three-layer uniaxially stretched multilayer film (vinyl alcohol-based copolymer layer (A) / polyolefin-based adhesive layer (H) / polyolefin base layer (G) = 4 μm / 4 μm / 40 μm).

[0088] A vapor-deposited film was prepared in the same manner as in Example 1 on the surface of the vinyl alcohol copolymer layer (A) of the obtained biaxially stretched multilayer film, in which a 40 nm-thick SiOx vapor-deposited layer (vapor-deposited layer (B)) was formed on the EVOH-2. A portion was cut out from the obtained vapor-deposited film and evaluated according to the method described in the above evaluation method (1). The results are shown in Table 1.

[0089] An adhesive solution was prepared by mixing 24 parts by weight of a two-component reactive polyurethane adhesive (24 parts by weight of "Takelac™ A-520" and 4 parts by weight of "Takenate™ A-50" manufactured by Mitsui Chemicals, Inc.) with 37 parts by weight of ethyl acetate. The adhesive solution was applied to the vapor-deposited surface of the resulting vapor-deposited film using a wire bar to a thickness of 2 μm after drying, dried at 100°C for 5 minutes, and laminated to the corona-treated side of the LLDPE to form a polyolefin layer (C) as a sealant layer. A multilayer structure having a layer thickness and layer structure of polyolefin substrate layer (G) / polyolefin adhesive layer (H) / vinyl alcohol-based polymer layer (A) / vapor-deposited layer (B) / polyurethane adhesive layer / sealant layer = 40 μm / 4 μm / 4 μm / 40 nm / 2 μm / 50 μm was prepared. The adhesion temperature (heating roll temperature) during lamination was 80°C, and after preparation of the multilayer structure, it was aged at 40°C for 3 days. The obtained multilayer structure was evaluated according to the above evaluation methods (2) to (4). The results are shown in Table 1.

[0090] Examples 10 to 13 Vapor-deposited films and multilayer structures were prepared and evaluated in the same manner as in Example 9, except that the conveying speed of the biaxially stretched multilayer film during vapor deposition was changed so that the thickness of the vapor-deposited layer (B) made of silicon oxide was 60 nm (Example 10), 80 nm (Example 11), 100 nm (Example 12), or 120 nm (Example 13). The results are shown in Table 1.

[0091] Example 14 A deposited film and a multilayer structure were prepared and evaluated in the same manner as in Example 10, except that the supply rate of oxygen blown during deposition was changed to 0.19 mL / min. The results are shown in Table 1.

[0092] Example 15 A vapor-deposited film was produced in the same manner as in Example 1. An adhesive solution was prepared by mixing a two-component reactive polyurethane adhesive (24 parts by mass of "Takelac™ A-520" and 4 parts by mass of "Takenate™ A-50" manufactured by Mitsui Chemicals, Inc.) with 37 parts by mass of ethyl acetate. The adhesive solution was applied to the corona-treated surface of BOPP (polyolefin layer (C)) using a wire bar to a thickness of 2 μm after drying, and the applied solution was dried at 100°C for 5 minutes. The resulting vapor-deposited film was then laminated to the vapor-deposited surface side. Next, the adhesive solution was applied to the corona-treated surface of the CPP using a wire bar to form a polyolefin layer (C) serving as a sealant layer, so that the thickness after drying would be 2 μm. The applied solution was then dried at 100° C. for 5 minutes, and laminated to the exposed surface of the polyolefin substrate layer (G) of the multilayer structure after lamination with the BOPP to produce a multilayer structure having a thickness and layer structure of BOPP layer / polyurethane adhesive layer / vapor-deposited layer (B) / vinyl alcohol-based polymer layer (A) / polyolefin adhesive layer (H) / polyolefin substrate layer (G) / polyurethane adhesive layer / sealant layer = 20 μm / 2 μm / 40 nm / 2 μm / 2 μm / 20 μm / 2 μm / 50 μm. The adhesion temperature (heating roll temperature) during lamination was 80° C., and after production of the multilayer structure, it was aged at 40° C. for 3 days. The resulting multilayer structure was evaluated according to the methods described in the above evaluation methods (2) to (4). The results are shown in Table 1.

[0093] [Example 16] Silicon oxide in the deposition chamber was replaced with aluminum oxide (AlO Ｘ A vapor-deposited film was prepared in the same manner as in Example 2, except that the temperature was changed to 100°C. A portion was cut out for measuring the vapor-deposited layer. Evaluation was performed according to the method described in the above evaluation method (1). The results are shown in Table 1.

[0094] 89.6 g of hydrochloric acid (0.1 N) was added to 10.4 g of tetraethoxysilane, and the mixture was stirred for 30 minutes to undergo hydrolysis and condensation, resulting in a solid content of 3 mass % (SiO ２A hydrolysis solution (based on the % wt. equivalent) was obtained. This solution was mixed with a 3% by mass aqueous solution of PVOH-1 at a mass ratio of 80 / 20 to prepare a coating solution for the protective layer. The resulting coating solution was applied to the surface of the alumina vapor-deposited layer AlOx of the vapor-deposited film obtained above using a wire bar so that the thickness after drying would be 2 μm, and the coating solution was dried at 100°C for 5 minutes to form a protective layer. In this way, a multilayer film was prepared having a layer structure and thickness of protective layer / vapor-deposited layer (B) / vinyl alcohol-based polymer layer (A) / polyolefin-based adhesive layer (H) / polyolefin substrate layer (G) = 2 μm / 60 nm / 2 μm / 2 μm / 20 μm. Using the resulting multilayer film, multilayer structures and products were produced and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0095] [Comparative Example 2] PET (Comparative Example 2) was used instead of EVOH-1, MAhPP2 instead of MAhPP1, and PP1 was used as the material for the polyolefin substrate layer (G), and a three-kind, three-layer multilayer film (PET / polyolefin adhesive layer (H) / polyolefin substrate layer (G) = 50 μm / 50 μm / 500 μm thick) was produced using a coextrusion film-forming device. The thickness of the multilayer film was adjusted by appropriately changing the screw rotation speed and take-up roll speed. The extruder, extrusion conditions, and die used were as follows: PET Extruder: Single-screw extruder (Toyo Seiki Co., Ltd., Lab Machine ME Type CO-EXT) Screw: Diameter 20 mmφ, L / D 20, Full-flight screw Extrusion temperature: Feeding section / Compression section / Metering section / Die = 260 / 260 / 260 / 260°C Polyolefin adhesive layer (H) Extruder: Single-screw extruder (Technovel Co., Ltd., SZW20GT-20MG-STD) Screw: Diameter 20 mmφ, L / D 20, Full-flight screw Extrusion temperature: Feeding section / Compression section / Metering section / Die = 150 / 200 / 220 / 230°C Polyolefin base layer (G) Extruder: Single-screw extruder (Plastics Technology Research Institute Co., Ltd., GT-32-A) Screw: Diameter 32 mmφ, L / D 28, Full-flight screw Extrusion temperature: feeding section / compression section / metering section / die = 170 / 220 / 230 / 230°C Die: 300mm wide, 3-type, 3-layer coat hanger die (manufactured by Plastics Engineering Research Institute) Die temperature: 260°C

[0096] The obtained multilayer film was stretched 5 times in the longitudinal direction and then 5 times in the transverse direction at 150°C using a tenter-type sequential biaxial stretching apparatus, to obtain a three-kind, three-layer biaxially oriented multilayer film (PET layer / polyolefin adhesive layer (H) / polyolefin base layer (G) = thickness of 2 μm / 2 μm / 20 μm).

[0097] A vapor-deposited film was prepared by forming a 60 nm-thick SiOx vapor-deposited layer (vapor-deposited layer (B)) on the PET surface of the obtained biaxially stretched multilayer film in the same manner as in Example 2. A portion was cut out for measuring the vapor-deposited layer. Evaluation was carried out according to the method described in the above evaluation method (1). The results are shown in Table 1.

[0098] A two-component reactive polyurethane adhesive (24 parts by mass of "Takelac™ A-520" and 4 parts by mass of "Takenate™ A-50" manufactured by Mitsui Chemicals, Inc.) was mixed with 37 parts by mass of ethyl acetate to prepare an adhesive solution. The adhesive solution was applied to the vapor-deposited surface of the obtained vapor-deposited film using a wire bar so that the thickness after drying was 2 μm, and then dried at 100 ° C. for 5 minutes. This was then laminated to the corona-treated side of the CPP to form a polyolefin layer (C) as a sealant layer, producing a multilayer structure having a thickness and layer structure of polyolefin substrate layer (G) / polyolefin adhesive layer (H) / PET layer / vapor-deposited layer (B) / polyurethane adhesive layer / sealant layer = 20 μm / 2 μm / 2 μm / 40 nm / 2 μm / 50 μm. The adhesion temperature (heating roll temperature) during lamination was 80 ° C., and after the multilayer structure was produced, it was aged at 40 ° C. for 3 days. The obtained multilayer structure was evaluated according to the above evaluation methods (2) to (4). The results are shown in Table 1.

[0099] Comparative Example 3 Except for using PA instead of PET, a vapor-deposited film and a multilayer structure were prepared and evaluated in the same manner as in Comparative Example 2. The results are shown in Table 1.

[0100] Comparative Example 4 A deposited film and a multilayer structure were prepared and evaluated in the same manner as in Comparative Example 2, except that the supply rate of oxygen blown during deposition was changed to 0 mL / min. The results are shown in Table 1.

[0101] Comparative Example 5 A deposited film and a multilayer structure were prepared and evaluated in the same manner as in Example 2, except that the supply rate of oxygen blown during deposition was changed to 0 mL / min. The results are shown in Table 1.

[0102] A vapor-deposited layer (B) formed on a biaxially stretched ethylene-vinyl alcohol copolymer film (ethylene unit content 32 mol%, saponification degree 99.9 mol%, thickness 12 μm) under the same conditions as in Comparative Example 5 was analyzed with a scanning X-ray photoelectron spectrometer. The molar ratios of silicon, oxygen, and carbon (total 100 mol%) were plotted against sputtering time in FIG. 3, and the molar ratio (O / Si) at that time was plotted against sputtering time in FIG. 4. Carbon derived from organic contamination on the vapor-deposited film surface was detected on surface (b2) at the start of sputtering, but carbon was no longer detected after etching proceeded for about 0.5 minutes. As etching proceeded, carbon derived from the EVOH layer (A) of the substrate began to be detected, and at 6.06 minutes when the carbon content reached 1 mol%, surface (b1) was reached, and the molar ratio of oxygen to silicon element (O / Si) at this time was ｂ１ In addition, at a sputtering time of 3.03 minutes, the molar ratio of oxygen element (O) to silicon element (Si) (O / Si) at positions equidistant from the surface (b1) and the surface (b2) was ｃ The ratio [(O / Si) ｂ１ / (O / Si) ｃ ] was 1.08, which revealed that the molar ratio (O / Si) near the interface with the EVOH layer (A) was smaller than in Example 2 in which oxygen was supplied during deposition.

[0103] Comparative Example 6 An aluminum oxide vapor-deposited film and a multilayer structure were prepared and evaluated in the same manner as in Example 16, except that the supply rate of oxygen blown during vapor deposition was changed to 0 mL / min. The results are shown in Table 1.

[0104] Comparative Example 7: Aluminum oxide (AlO) in the deposition chamber Ｘ A vapor-deposited film and a multilayer structure were prepared and evaluated in the same manner as in Example 16, except that the fluorine-containing polymer (F) was replaced with aluminum (Al). The results are shown in Table 1.

[0105] Comparative Example 8 A deposited film was prepared and evaluated in the same manner as in Example 2, except that the supply rate of oxygen blown during deposition was changed to 0.10 mL / min. The results are shown in Table 1.

[0106] Comparative Example 9 A vapor-deposited film was prepared and evaluated in the same manner as in Example 16, except that PET was used instead of EVOH-1. The results are shown in Table 1.

[0107] Comparative Example 10 A vapor-deposited film was prepared and evaluated in the same manner as in Example 16, except that PET was used instead of EVOH-1 and the amount of oxygen blown during vapor deposition was changed to 0 mL / min. The results are shown in Table 1.

[0108]

[0109] Example 17: 6 parts of ethylene-vinyl alcohol copolymer EVOH-3 and 92 parts of a mixed solvent (water / n-propanol = 8 / 2) were heated with stirring at 95 ° C for 1 hour, and the mixture was then stopped and stirred until the temperature returned to room temperature, yielding an aqueous PVOH-1 solution. A two-component reactive polyurethane adhesive (1.5 parts by mass of "Takelac (trademark) A-626" and 0.188 parts by mass of "Takenate (trademark) A-50" manufactured by Mitsui Chemicals, Inc.) was mixed with 32.5 parts by mass of ethyl acetate to prepare an anchor coat solution. BOPP was used as the polyolefin substrate layer (G), and the anchor coat solution was applied to the corona-treated surface of the BOPP with a wire bar to a dry thickness of 0.2 μm. The solution was then dried at 100 ° C for 5 minutes to form an anchor coat layer. The EVOH-3 aqueous solution prepared above was applied onto the anchor coat layer with a wire bar so that the thickness after drying would be 0.5 μm, and then dried at 100° C. for 5 minutes to form a barrier layer.

[0110] A vapor-deposited film was prepared by forming a 60 nm-thick SiOx vapor-deposited layer (vapor-deposited layer (B)) on the EVOH surface of the obtained multilayer film in the same manner as in Example 2. A portion was cut out for measuring the vapor-deposited layer. Evaluation was carried out according to the method described in the above evaluation method (1). The results are shown in Table 2.

[0111] An adhesive solution was prepared by mixing 24 parts by weight of a two-component reactive polyurethane adhesive (24 parts by weight of "Takelac™ A-520" and 4 parts by weight of "Takenate™ A-50" manufactured by Mitsui Chemicals, Inc.) with 37 parts by weight of ethyl acetate. The adhesive solution was applied to the vapor-deposited surface of the obtained vapor-deposited film using a wire bar so that the thickness after drying was 2 μm, and then dried at 100 ° C for 5 minutes. This was then laminated to the corona-treated side of the CPP to form a polyolefin layer (C) as a sealant layer, producing a multilayer structure having a layer thickness and layer structure of polyolefin substrate layer (G) / polyurethane adhesive layer / vinyl alcohol polymer layer (A) / vapor-deposited layer (B) / polyurethane adhesive layer / sealant layer = 20 μm / 0.2 μm / 0.5 μm / 40 nm / 2 μm / 50 μm. The adhesion temperature (heating roll temperature) during lamination was 80 ° C., and after the multilayer structure was produced, it was aged at 40 ° C. for 3 days. The obtained multilayer structure was evaluated according to the methods described in the above evaluation methods (2) to (4). The results are shown in Table 2.

[0112] [Examples 18 and 19] Vapor-deposited films and multilayer structures were prepared and evaluated in the same manner as in Example 17, except that PVOH-1 (Example 18) and EVOH-2 (Example 19) were used instead of EVOH-3 as the material for the vinyl alcohol polymer layer (A). In Example 19, a mixed solvent (water / n-propanol = 35 / 65) was used. The results are shown in Table 2.

[0113]

[0114] Example 20 The multilayer structure obtained in Example 1 was pulverized into pieces measuring 5 mm square or less. This pulverized material was blended with polyethylene resin (Novatec™ LD LJ400, manufactured by Japan Polyethylene Corporation; low-density polyethylene, melting point 108°C) at a mass ratio (pulverized material / polyethylene resin) of 40 / 60. A single-layer film was formed under the extrusion conditions shown below to obtain a 50 μm-thick recycled composition film. The film thickness was adjusted by appropriately changing the screw rotation speed and take-up roll speed. A control polyethylene film of 50 μm thickness was also obtained using only polyethylene resin. Extruder: Single-screw extruder manufactured by Toyo Seiki Seisakusho, Ltd. Screw diameter: 20 mmφ (L / D = 20, compression ratio = 3.5, full-flight type) Extrusion temperature: C1 / C2 / C3 / D = 160 / 190 / 190 / 190°C Take-up roll temperature: 50°C. The recycled composition exhibited stable and favorable extrusion processability. The recovered composition film had almost the same amount of gels and particles as the polyethylene film, and had a uniform and good appearance except for slight discoloration.

Claims

1. A multilayer structure comprising a polyolefin layer (C) and a vapor-deposited film (X) including a vinyl alcohol polymer layer (A) and a vapor-deposited layer (B) made of silicon oxide or metal oxide, wherein the vapor-deposited layer (B) having a thickness of 30 nm to 200 nm is formed directly on the surface of the vinyl alcohol polymer layer (A), and the surface of the vapor-deposited layer (B) facing the vinyl alcohol polymer layer (A) is designated as surface (b1), the surface opposite to the vapor-deposited layer (B) is designated as surface (b2), and when elemental analysis of the vapor-deposited layer (B) is performed in the depth direction from surface (b2) to surface (b1) using a scanning X-ray photoelectron spectrometer, the molar ratio (O / M) of oxygen element (O) to silicon element or metal element (M) in surface (b1) is ｂ１ and the molar ratio (O / M) of oxygen element (O) to silicon element or metal element (M) at positions equidistant from the surface (b1) and the surface (b2). ｃ The ratio [(O / M) ｂ１ / (O / M) ｃ ] is 1.1 or more and 1.7 or less, the thickness of the vinyl alcohol-based polymer layer (A) is 0.1 μm or more and less than 20 μm, and the ratio of the thickness of the layer containing polyolefin as a main component to the total thickness of the multilayer structure is 75% or more.

2. The multilayer structure according to claim 1, wherein the vapor-deposited layer (B) consists of silicon oxide or aluminum oxide.

3. The multilayer structure according to claim 2, wherein the vapor-deposited layer (B) consists of silicon oxide.

4. The molar ratio (O / M) ｂ１ 2. The multilayer structure according to claim 1, wherein the σ is 1.85 or greater and 2.35 or less.

5. The molar ratio (O / M) ｃ The multilayer structure according to claim 1, wherein the σ is 1.5 or more and 2.0 or less.

6. The multilayer structure according to any one of claims 1 to 5, wherein the vapor-deposited film (X) comprises a polyolefin substrate layer (G), a polyolefin-based adhesive layer (H), a vinyl alcohol-based polymer layer (A), and a vapor-deposited layer (B) in this order.

7. The multilayer structure according to claim 6, wherein the polyolefin substrate layer (G), the polyolefin adhesive layer (H) and the vinyl alcohol polymer layer (A) are coextruded.

8. The multilayer structure according to claim 6, wherein the polyolefin substrate layer (G), the polyolefin adhesive layer (H) and the vinyl alcohol polymer layer (A) are stretched at least uniaxially.

9. The multilayer structure according to claim 6, wherein the vinyl alcohol polymer layer (A) contains, as a main component, an ethylene-vinyl alcohol copolymer having an ethylene unit content of 10 to 65 mol % and a saponification degree of 90 mol % or more.

10. The multilayer structure according to any one of claims 1 to 5, wherein the vapor-deposited film (X) comprises a polyolefin substrate layer (G), a vinyl alcohol-based polymer layer (A), and a vapor-deposited layer (B) in this order.

11. The multilayer structure according to claim 10, wherein the vinyl alcohol polymer layer (A) is formed by coating a solution or dispersion of a vinyl alcohol polymer on the polyolefin substrate layer (G).

12. The multilayer structure according to claim 10, wherein the vinyl alcohol polymer layer (A) contains, as a main component, a vinyl alcohol polymer having an ethylene unit content of 50 mol % or less and a saponification degree of 70 mol % or more.

13. The multilayer structure according to any one of claims 1 to 5, which has a plurality of polyolefin layers (C), one of which is an unoriented polyolefin layer and the other of which is an oriented polyolefin layer.

14. The multilayer structure according to any one of claims 1 to 5, which does not contain a layer containing as its main component a resin having a melting point of 200°C or higher, or a metal layer having a thickness of 1 μm or more.

15. A packaging material comprising the multilayer structure of any one of claims 1 to 5.

16. A package comprising the packaging material according to claim 15 and a content therein, wherein the content contains 5% by mass or more of water and at least one selected from the group consisting of 1% by mass or more of lipids, 1% by mass or more of sodium chloride, and 0.5% by mass or more of acetic acid.

17. A recovered composition comprising a recovered multilayer structure according to any one of claims 1 to 5.

18. A method for recovering a multilayer structure, comprising crushing the multilayer structure according to any one of claims 1 to 5 and then melt-molding it.

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