Package, and product with content

Abstract

To provide a product capable of suppressing degradation of each of appearance, adhesion strength, and a barrier property even when storing a content containing sodium chloride while maintaining recyclability, despite the fact that a high barrier property is generated similarly to a polyolefin based multi-layered structure having an inorganic vapor-deposited layer constituted from aluminum on a barrier layer such as EVOH or the like.SOLUTION: A product has: a package comprising a multilayer structure having a barrier layer (A) containing EVOH (a) as a main component, an inorganic oxide vapor-deposited layer (B) containing at least one selected from the group consisting of aluminum oxide and silicon oxide, and a heat seal layer (E), the barrier layer (A) and the inorganic oxide vapor-deposited layer (B) being directly laminated; and a content containing 1.0 mass% or more of sodium chloride inside the package, wherein the heat seal layer (E) is located at an outermost layer on an inner face side of the package, and has a protective layer (F) directly laminated on the inorganic oxide vapor-deposited layer (B) when the inorganic oxide vapor-deposited layer (B) contains aluminum oxide as a main component.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a product having a package and contents.

Background Art

[0002] Packaging materials for long-term preservation of foods often require gas barrier properties including oxygen barrier properties. By using a packaging material with high gas barrier properties, oxidative deterioration of foods due to oxygen ingress and proliferation of microorganisms can be suppressed. As layers for improving gas barrier properties, metal foils such as aluminum, metal vapor deposition, and inorganic oxide vapor deposition layers such as silicon oxide and aluminum oxide are widely used. On the other hand, resin layers having gas barrier properties such as vinyl alcohol-based polymers and polyvinylidene chloride are also widely used. Vinyl alcohol-based polymers have a feature of exhibiting gas barrier properties by crystallization and densification due to hydrogen bonding between hydroxyl groups in the molecule. Among them, ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as "EVOH") is suitable for melt molding because of its excellent thermal stability. With the development of coextrusion technology, multilayer films having an EVOH layer as an intermediate layer are widely used as gas barrier packaging materials (Patent Document 1).

[0003] In recent years, due to environmental and waste issues, the demand for so-called post-consumer recycling (hereinafter sometimes simply abbreviated as recycling), which involves recovering and recycling packaging materials consumed in the market, has been increasing globally. In recycling, the general process is to cut the recovered packaging materials, separate and wash them if necessary, and then melt and mix them using an extruder. Using the pellets thus obtained, various molded articles are manufactured. In this regard, it is required that the packaging material be composed of a single material as much as possible (monomaterialization), so that a high-purity and high-quality recycled resin can be obtained. For this purpose, the demand for barrier films mainly made of polyolefin, which is widely used as a packaging material, has been increasing. There has also been proposed a vapor-deposited multilayer film that laminates an inorganic vapor-deposited layer on the EVOH layer of a polypropylene-based multilayer film having an EVOH layer, achieving both gas barrier properties and recyclability (Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in a package using a polyolefin-based multilayer structure having an inorganic vapor-deposited layer composed of aluminum on a barrier layer such as EVOH, it has been found that when storing contents containing sodium chloride, the appearance of the package may deteriorate, the adhesion strength may decrease, and the barrier property may decrease. On the other hand, when using a package with an aluminum foil laminated instead of the inorganic vapor-deposited layer for the purpose of suppressing appearance deterioration, it is difficult to uniformly mix with other components in the melt mixing process when recycling, and it has been difficult to maintain a good balance among appearance characteristics, barrier properties, and recyclability.

[0006] In view of such a situation, an object of the present invention is to exhibit high barrier properties similar to those of a polyolefin-based multilayer structure having an inorganic vapor deposition layer composed of aluminum on a barrier layer such as EVOH, while maintaining recyclability, and to suppress deterioration of appearance, decrease in adhesion strength, and decrease in barrier properties even when storing a content containing sodium chloride. An object is to provide a product that can do so.

Means for Solving the Problems

[0007] According to the present invention, the above object is [1] A package comprising a multilayer structure having a barrier layer (A) mainly containing an ethylene-vinyl alcohol copolymer (a) (hereinafter may be abbreviated as "EVOH (a)"), an inorganic oxide vapor deposition layer (B) containing at least one selected from the group consisting of aluminum oxide and silicon oxide, and a heat seal layer (E) mainly containing a polyolefin resin (e), and having a layer structure in which the barrier layer (A) and the inorganic oxide vapor deposition layer (B) are directly laminated, and a content containing 1.0% by mass or more of sodium chloride inside the package, wherein the heat seal layer (E) is located on the outermost surface on the inner surface side of the package, and when the inorganic oxide vapor deposition layer (B) contains aluminum oxide as a main component, it has a protective layer (F) directly laminated on the inorganic oxide vapor deposition layer (B); [2] The product according to [1], wherein the barrier layer (A) is stretched at least uniaxially; [3] The product according to [1] or [2], wherein the average thickness of the barrier layer (A) is 0.1 μm or more and 20 μm or less; [4] The product according to any one of [1] to [3], wherein the ratio of the average thickness of the barrier layer (A) to the average thickness of the multilayer structure is 5% or less; [5] The product according to any one of [1] to [4], wherein the average thickness of the inorganic oxide vapor deposition layer (B) is 10 to 200 nm; [6] The product according to any one of [1] to [5], wherein the average thickness of the heat seal layer (E) is 5 μm or more and 200 μm or less; [7] The multilayer structure includes an adhesive layer (C) containing an adhesive resin (c) as a main component and a polyolefin layer (D) containing a polyolefin resin (d) as a main component, and has a layer structure in which an inorganic oxide vapor deposition layer (B), a barrier layer (A), the adhesive layer (C), and the polyolefin layer (D) are laminated in this order, any of the products of [1] to [6]; [8] The product of [7], wherein the barrier layer (A), the adhesive layer (C), and the polyolefin layer (D) are stretched at least in one axial direction; [9] The product of [7] or [8], wherein the barrier layer (A), the adhesive layer (C), and the polyolefin layer (D) are coextruded films;

[10] The product of any of [7] to [9], wherein the resins that are the main components of the polyolefin layer (D) and the heat seal layer (E) are of the same resin type;

[11] The multilayer structure may have an adhesive layer (G) containing an adhesive (g) as a main component. When the adhesive layer (G) is included, the total average thickness of the adhesive layer (G) is 10 μm or less, any of the products of [1] to

[10] ;

[12] The product of any of [1] to

[11] , wherein the sodium chloride content of the content is 5% by mass or less;

[13] The product of any of [1] to

[12] , wherein the content contains moisture;

[14] The product of

[13] , wherein the moisture content of the content is 70% by mass or less;

[15] The product of any of [1] to

[14] , wherein the content contains lipids;

[16] The product of

[15] , wherein the lipid content of the content is 95% by mass or less;

[17] The product of any of [1] to

[16] , wherein the pH of the content is 1.0 or more and 6.0 or less; It is achieved by providing.

Advantages of the Invention

[0008] According to the present invention, it is possible to provide a package that suppresses deterioration in appearance, decrease in adhesion strength, and decrease in barrier properties when storing contents containing sodium chloride while maintaining recyclability. Here, the "recyclability" in this specification means that when the recovered product of the package of the present invention is melt-kneaded to produce a recovered composition, the generation of lumps is suppressed and a recovered composition with excellent appearance can be efficiently produced, and it can be evaluated by the recyclability test described in the examples.

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described. In the following description, specific materials (compounds, etc.) may be exemplified as those that exhibit specific functions, but the present invention is not limited to embodiments using such materials. Further, the exemplified materials may be used alone or in combination unless otherwise specified.

[0010] The product of the present invention includes a barrier layer (A) containing EVOH (a) as a main component, an inorganic oxide vapor deposition layer (B) containing at least one selected from the group consisting of aluminum oxide and silicon oxide, and a heat seal layer (E), and has a multilayer structure in which the barrier layer (A) and the inorganic oxide vapor deposition layer (B) are directly laminated. It has a package, and contents containing 1.0% by mass or more of sodium chloride inside the package, and the heat seal layer (E) is located on the outermost surface on the inner surface side of the package. Further, when the inorganic oxide vapor deposition layer (B) contains aluminum oxide as a main component, it has a protective layer (F) directly laminated on the inorganic oxide vapor deposition layer (B). By having the above configuration, the product of the present invention has good recyclability and can suppress deterioration in appearance, decrease in adhesion strength, and decrease in barrier properties when stored in a state of having contents containing 1.0% by mass or more of sodium chloride.

[0011] In the present specification, the "main component" means a component contained in an amount exceeding 50% by mass. The "average thickness" of each layer, etc. means the average value of the thicknesses measured at any five locations unless otherwise specified. "ppm" means the content based on mass (ppm by mass). "Polyethylene" refers to a homopolymer of ethylene, a copolymer of 80 mol% or more of ethylene and 20 mol% or less of an α-olefin monomer, and a copolymer of 90 mol% or more of ethylene and less than 10 mol% of a non-olefin monomer whose functional group contains no atoms other than carbon atoms, oxygen atoms and hydrogen atoms. "Polypropylene" refers to a homopolymer of propylene, a copolymer of 80 mol% or more of propylene and 20 mol% or less of an α-olefin monomer, and a copolymer of 90 mol% or more of propylene and less than 10 mol% of a non-olefin monomer whose functional group contains no atoms other than carbon atoms, oxygen atoms and hydrogen atoms. "Acid-modified polyethylene" refers to a polymer obtained by modifying polyethylene with an acid. The acid-modified polyethylene may be a polymer in which at least one of an acidic group and an acid anhydride group is introduced into the polyethylene. "Acid-modified polypropylene" refers to a polymer obtained by modifying polypropylene with an acid. The acid-modified polypropylene may be a polymer in which at least one of an acidic group and an acid anhydride group is introduced into the polypropylene. "Acid-modified polyolefin" refers to a polymer obtained by modifying a polyolefin with an acid. The acid-modified polyolefin may be a polymer in which at least one of an acidic group and an acid anhydride group is introduced into the polyolefin. "Polyolefin resin" refers to polyolefin and modified polyolefin (such as acid-modified polyolefin). Modified polyolefin refers to a polymer obtained by modifying a polyolefin. "Polyolefin-based multilayer structure" means a multilayer structure in which the average thickness ratio of the layer containing a polyolefin resin as a main component is 70% or more. In addition, the "surface (or surface layer)" in a multilayer film or multilayer structure does not mean to distinguish between the front and back, but refers to the exposed surface. That is, there are two surfaces in a multilayer film or multilayer structure. Similarly, there are two outermost layers in a multilayer film or multilayer structure. In addition, in this specification, "substantially consisting only of" allows the inclusion of optional components as long as the effects of the present invention are not affected, and "consisting only of" means excluding optional components other than unavoidably included impurities. "Barrier property" means oxygen barrier property and water vapor barrier property, "gas barrier property" means oxygen barrier property, and the barrier property can be evaluated by the method described in the examples.

[0012] [Barrier layer (A)] The multilayer structure in the product of the present invention includes a barrier layer (A) mainly composed of EVOH (a), so that the gas barrier property is improved. In addition, since the barrier layer (A) has good affinity with the inorganic oxide vapor deposition layer (B) described later, when the barrier layer (A) and the inorganic oxide vapor deposition layer (B) are directly laminated, good adhesion strength can be exhibited, and a good barrier property tends to be shown. Also, surprisingly, when the barrier layer (A) and the inorganic oxide vapor deposition layer (B) are directly laminated, even after storing a content containing 1.0% by mass or more of sodium chloride, deterioration of appearance, decrease in adhesion strength, and decrease in barrier property can be more suppressed. Note that the barrier layer (A) may be a single layer or a plurality of layers. When a plurality of layers are provided, at least one of the plurality of barrier layers (A) may be directly laminated with the inorganic oxide vapor deposition layer (B), and a barrier layer (A) not directly laminated with the inorganic oxide vapor deposition layer (B) may be provided.

[0013] EVOH(a) is usually obtained by saponifying an ethylene-vinyl ester copolymer obtained by polymerizing ethylene and a vinyl ester. The ethylene unit content of EVOH(a) is preferably 10 mol% or more and 65 mol% or less, more preferably 20 mol% or more and 60 mol% or less, and even more preferably 25 mol% or more and 55 mol% or less. When the ethylene unit content of EVOH(a) is 10 mol% or more, the melt moldability of EVOH(a) is improved. Also, when the ethylene unit content of EVOH(a) is 65 mol% or less, the gas barrier property of the multilayer structure in the product of the present invention is improved. Further, the saponification degree of EVOH(a) is preferably 90 mol% or more. The saponification degree means the ratio of the number of vinyl alcohol units to the total number of vinyl alcohol units and vinyl ester units in EVOH(a). The saponification degree of EVOH(a) is more preferably 95 mol% or more, and even more preferably 99 mol% or more. When the saponification degree is 90 mol% or more, the gas barrier property of the multilayer structure in the product of the present invention tends to be improved. The ethylene unit content and the saponification degree of EVOH(a) are 1 determined by 1H-NMR measurement.

[0014] EVOH(a) may be a mixture of two or more types of EVOH having different ethylene unit contents. In this case, the difference in the ethylene unit contents between the EVOHs with the most different ethylene unit contents is preferably 30 mol% or less, more preferably 20 mol% or less, even more preferably 15 mol% or less, and may be 3 mol% or more. Similarly, EVOH(a) may be a mixture of two or more types of EVOH having different saponification degrees. In this case, the difference in the saponification degrees between the EVOHs with the most different saponification degrees is preferably 7% or less, more preferably 5% or less, and may be 0.5 mol% or more.

[0015] EVOH(a) may contain other monomer units other than ethylene, vinyl ester, and vinyl alcohol as long as the effects of the present invention are not inhibited. In particular, by introducing a modified group containing a primary hydroxyl group having a specific structure, it may be possible to achieve both high gas barrier properties and moldability of EVOH(a) at a high level. The content of other monomer units is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 1% by mass or less, and in some cases, it is particularly preferable that it is substantially not contained. Examples of other monomers include alkenes such as propylene, butylene, pentene, and hexene; esters having an ester group such as 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, 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-methylenepropane, or their saponified products; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, and itaconic acid, 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, and methallyl sulfonic acid, or their salts; vinyl silane compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxy-ethoxy)silane, and γ-methacryloxypropylmethoxysilane; alkyl vinyl ethers, vinyl ketones, N-vinylpyrrolidone, vinyl chloride, vinylidene chloride, etc.

[0016] EVOH(a) may be post-modified by methods such as urethanization, acetalization, cyanoethylation, oxyalkylation, etc.

[0017] The melt flow rate (MFR) (at 210 °C and under a load of 2.16 kg) measured in accordance with JIS K7210 (2014) of EVOH (a) is preferably 0.2 to 30 g / 10 min. The MFR of EVOH (a) is more preferably 1.0 g / 10 min or more, still more preferably 5.0 g / 10 min or more, and particularly preferably 10 g / 10 min or more. On the other hand, the MFR of EVOH (a) is more preferably 25 g / 10 min or less, still more preferably 20 g / 10 min or less.

[0018] The barrier layer (A) can also contain other compounds other than EVOH (a) as long as the effects of the present invention are not inhibited. Examples of the other compounds include carboxylic acid compounds, phosphoric acid compounds, boron compounds, metal salts (alkali metal salts, alkaline earth metal salts), antioxidants, ultraviolet absorbers, plasticizers, lubricants, fillers, antistatic agents, and the like. The content of the other compounds in the barrier layer (A) is usually 5% by mass or less, preferably 2% by mass or less, more preferably 1% by mass or less, and still more preferably 0.5% by mass or less. From the viewpoint of suppressing lumps and coloring when melt-molding the pulverized product of the multilayer structure containing the barrier layer (A), it is preferable to contain an alkali metal salt, a carboxylic acid compound portion and / or a phosphoric acid compound. Further, by containing a boron compound, the melt viscosity of the barrier layer (A) and the pulverized product of the multilayer structure containing the barrier layer (A) can be controlled.

[0019] The carboxylic acid compound may be a monocarboxylic acid, a polycarboxylic acid, or a combination thereof. The carboxylic acid compound may be an ion, and such a carboxylic acid ion may form a salt with a metal ion. The content of the carboxylic acid and the carboxylic acid ion is preferably 50 to 400 ppm. As the carboxylic acid compound, for example, aliphatic carboxylic acids such as acetic acid and stearic acid are preferably used. When the barrier layer (A) contains a carboxylic acid compound, it tends to prevent coloring during melt molding.

[0020] The phosphate compound is not particularly limited, and various acids such as phosphoric acid and phosphorous acid, and their salts can be used. As the phosphate, it may be contained in any form of primary phosphate, secondary phosphate, or tertiary phosphate, but primary phosphate is preferred. The cation species thereof is not particularly limited, but an alkali metal salt is preferred. Among them, sodium dihydrogen phosphate and potassium dihydrogen phosphate are preferred. When the barrier layer (A) contains a phosphate compound, the content of the phosphate compound is preferably 5 to 100 ppm in terms of phosphate radical. When the content of the phosphate compound is 5 ppm or more, the color resistance during melt molding tends to be good. On the other hand, when the content of the phosphate compound is 100 ppm or less, the melt moldability tends to be good.

[0021] The boron compound is not particularly limited, and examples include boric acids, boric acid esters, borates, boron hydrides, etc. Specifically, examples of boric acids include orthoboric acid, metaboric acid, tetraboric acid, etc., examples of boric acid esters include triethyl borate, trimethyl borate, etc., and examples of borates include alkali metal salts, alkaline earth metal salts of the above various boric acids, borax, etc. Among these compounds, orthoboric acid (hereinafter may be simply referred to as boric acid) is preferred. When the barrier layer (A) contains a boron compound, the content of the boron compound is preferably 50 to 400 ppm in terms of boron element. When the content of the boron compound is 50 ppm or more, the torque fluctuation during heating and melting can tend to be suppressed. On the other hand, when the content of the boron compound is 400 ppm or less, the moldability can tend to be kept good.

[0022] The cationic species of the alkali metal salt are not particularly limited, but sodium salts or potassium salts are preferred. The anionic species of the alkali metal salt are also not particularly limited. It can be added as carboxylate, carbonate, bicarbonate, phosphate, hydrogen phosphate, borate, hydroxide, etc. When the barrier layer (A) contains an alkali metal salt, the content of the alkali metal salt is preferably 40 to 500 ppm in terms of metal element conversion. When the content of the alkali metal salt is 40 ppm or more, the interlayer adhesion tends to be good. On the other hand, when the content of the alkali metal salt is 500 ppm or less, the melt stability tends to be excellent.

[0023] The cationic species of the alkaline earth metal salt are not particularly limited, but magnesium salts or calcium salts are preferred. The anionic species of the alkaline earth metal salt are also not particularly limited. It can be added as carboxylate, carbonate, bicarbonate, phosphate, hydrogen phosphate, borate, hydroxide, etc. The content of the alkaline earth metal salt is preferably 10 to 300 ppm. When the barrier layer (A) contains an alkaline earth metal salt, the generation of deteriorated products such as gels can be suppressed when the molded body is repeatedly melt-molded. It is also preferable to use polyvalent metal salts such as zinc salts instead of the alkaline earth metal salts.

[0024] Examples of the antioxidant include 2,5-di-t-butylhydroquinone, 2,6-di-t-butyl-p-cresol, 4,4'-thiobis(6-t-butylphenol), 2,2'-methylenebis(4-methyl-6-t-butylphenol), octadecyl-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate, 4,4'-thiobis(6-t-butylphenol), etc.

[0025] Examples of the ultraviolet absorber include ethylene-2-cyano-3,3'-diphenyl acrylate, 2-(2'-hydroxy-5'-methylphenyl) benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl) 5-chlorobenzotriazole, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, and the like.

[0026] Examples of the plasticizer include dimethyl phthalate, diethyl phthalate, dioctyl phthalate, wax, liquid paraffin, phosphate ester, and the like.

[0027] Examples of the lubricant include stearic acid amide, oleic acid amide, erucic acid amide, behenic acid amide, ethylene bisstearic acid amide, methylol stearic acid amide, N-oleyl palmitamide, N-stearyl erucamide, liquid paraffin, natural paraffin, synthetic paraffin, polyolefin wax, stearyl alcohol, lauryl alcohol, stearic acid, lauric acid, myristic acid, behenic acid, montanic acid, stearyl stearate, stearyl laurate, calcium stearate, magnesium stearate, zinc stearate, lead stearate, and the like.

[0028] Examples of the filler include glass fiber, asbestos, ballastite, calcium silicate, and the like.

[0029] Examples of the antistatic agent include glycerin mono-fatty acid ester, fatty acid diethanolamide, alkyl diethanolamine, alkyl sulfonate, alkyl benzene sulfonate, alkyl trimethyl ammonium salt, alkyl benzyl dimethyl ammonium salt, alkyl betaine, alkyl imidazolium betaine, and the like.

[0030] The barrier layer (A) may further contain a thermoplastic resin other than EVOH (a). Examples of the thermoplastic resin other than EVOH (a) include various polyolefins (such as polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene-propylene copolymer, copolymer of ethylene and an α-olefin having 4 or more carbon atoms, copolymer of polyolefin and maleic anhydride, ethylene-vinyl ester copolymer, ethylene-acrylic ester copolymer, or a modified polyolefin obtained by graft-modifying these with an unsaturated carboxylic acid or its derivative, etc.), various polyamides (such as nylon 6, nylon 6·6, nylon 6 / 66 copolymer, nylon 11, nylon 12, polymetaxylylene adipamide, etc.), various polyesters (such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.), polyvinyl chloride, polyvinylidene chloride, polystyrene, polyacrylonitrile, polyurethane, polycarbonate, polyacetal, polyacrylate, and modified polyvinyl alcohol resin, etc. The content of the thermoplastic resin in the barrier layer (A) is usually less than 40% by mass, preferably less than 30% by mass, more preferably less than 20% by mass, still more preferably less than 10% by mass, and may even be less than 5% by mass or less than 1% by mass, and it is particularly preferable that it is substantially not contained.

[0031] From the viewpoint that the effects of the present invention are more remarkable, the proportion of EVOH (a) in the resin constituting the barrier layer (A) is preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and may be 98% by mass or more, or 99% by mass or more. The resin constituting the barrier layer (A) may be substantially only EVOH (a), and may be only EVOH (a), and may be 100% by mass or less. Further, from the viewpoint that the effects of the present invention are more remarkable, the proportion of EVOH (a) in the barrier layer (A) is preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and may be 98% by mass or more, or 99% by mass or more. The barrier layer (A) may be substantially composed of only EVOH (a), and may be 100% by mass or less.

[0032] The barrier layer (A) is preferably stretched at least in one axial direction. That is, the barrier layer (A) is preferably uniaxially or biaxially stretched. When the barrier layer (A) is a stretched layer, particularly when it is a biaxially stretched layer, a relatively thin barrier layer (A) can have good gas barrier properties. Further, since the barrier layer (A) is stretched at least in one axial direction, a decrease in adhesion strength can be more suppressed even after storing the product of the present invention, and thus a decrease in barrier properties after storing the product of the present invention can be more suppressed.

[0033] When the barrier layer (A) is a stretched layer, for example, it is preferably stretched 2 times or more and less than 12 times at least in one axial direction, and more preferably stretched 3 times or more and less than 6 times at least in one axial direction. Further, it is also preferable that the barrier layer (A) is stretched 2 times or more and less than 12 times in each biaxial direction, and more preferably stretched 2 times or more and less than 6 times in each biaxial direction.

[0034] The lower limit of the average thickness of the barrier layer (A) is preferably 0.1 μm, more preferably 0.3 μm. By making the average thickness of the barrier layer (A) equal to or greater than the above lower limit, the adhesion strength and barrier properties can be enhanced. The upper limit of the average thickness of the barrier layer (A) is preferably 20 μm, more preferably 15 μm, and may also be 10 μm, 5 μm, 3 μm, 2 μm, or 1 μm. By making the average thickness of the barrier layer (A) equal to or less than the above upper limit, the thinning and weight reduction of the multilayer structure can be achieved. Further, since the thickness ratio of the barrier layer (A) in the multilayer structure can be decreased, the recyclability of the product of the present invention tends to be enhanced.

[0035] The oxygen transmission rate of the barrier layer (A) is preferably 50 cc·20 μm / (m 2 ·day·atm) or less, more preferably 10 cc·20 μm / (m 2 ·day·atm) or less, even more preferably 5 cc·20 μm / (m 2 ·day·atm) or less, and particularly preferably 1 cc·20 μm / (m 2 ·day·atm) or less. Here, the oxygen transmission rate is a value measured according to the method described in ISO21309-2 Annex C (2019) under the conditions of 20°C and 65% RH.

[0036] The production method of the barrier layer (A) is not particularly limited, and examples thereof include a melting method, a solution method, a calendar method, etc., and among these, the melting method is preferred. Examples of the melting method include a casting method and an inflation method, and among these, the casting method is preferred. Further, the obtained barrier layer (A) may be stretched by a known method.

[0037] The production method of the resin composition which is the raw material for forming the barrier layer (A) is not particularly limited, but it can be produced by melt-kneading EVOH (a) and, if necessary, the other compounds. Each component may be blended in a solid state such as powder, or as a melt, or as a solute contained in a solution or a disperse phase contained in a dispersion. As the solution and the dispersion, an aqueous solution and an aqueous dispersion are respectively preferred. For melt-kneading, known mixing devices or kneading devices such as a kneader extruder, an extruder, a mixing roll, and a Banbury mixer can be used. The temperature range during melt-kneading can be appropriately adjusted according to the melting points of the EVOH (a) and each component used, and usually, 150 to 250 °C is adopted. Also, it may be produced by previously adding some components (other compounds) to EVOH (a) and then melt-kneading the other necessary components as described above. Examples of the method of previously adding some components (other compounds) to EVOH (a) include immersing EVOH (a) as pellets or powder in a solution in which the added component is dissolved. As the solution, an aqueous solution is preferred.

[0038] [Inorganic oxide vapor deposition layer (B)] The multilayer structure in the product of the present invention includes an inorganic oxide vapor deposition layer (B) containing at least one selected from the group consisting of aluminum oxide (alumina, AlOx) and silicon oxide (silica, SiOx), and has a layer structure in which the barrier layer (A) and the inorganic oxide vapor deposition layer (B) are directly laminated. Since the barrier layer (A) and the inorganic oxide vapor deposition layer (B) have good affinity, having a layer structure in which the barrier layer (A) and the inorganic oxide vapor deposition layer (B) are directly laminated tends to result in excellent adhesion strength and barrier properties of the multilayer structure. Also, surprisingly, when the barrier layer (A) and the inorganic oxide vapor deposition layer (B) are directly laminated, it is possible to suppress deterioration of appearance, decrease in adhesion strength, and decrease in barrier properties even when storing a content containing 1.0 mass% or more of sodium chloride. In this regard, even when an aluminum vapor deposition layer is directly laminated on the barrier layer (A), it exhibits good adhesion strength and barrier properties similar to those when the inorganic oxide vapor deposition layer (B) is directly laminated, but when storing a content containing 1.0 mass% or more of sodium chloride, it had problems such as deterioration of appearance, decrease in adhesion strength, and decrease in barrier properties. The product of the present invention solves such problems. By solving such problems, even when using a multilayer structure having an aluminum vapor deposition layer, even if the content contains 1.0 mass% or more of sodium chloride, it is possible not only to suppress deterioration of appearance, decrease in adhesion strength, and decrease in barrier properties, but also to provide a product with excellent recyclability.

[0039] The inorganic oxide used for the inorganic oxide vapor deposition layer (B) preferably contains silicon oxide (silica, SiOx). In the inorganic oxide vapor deposition layer (B), the proportion occupied by at least one selected from the group consisting of aluminum oxide and silicon oxide is preferably 50 mass% or more, more preferably 70 mass% or more, further preferably 90 mass% or more, particularly preferably 95 mass% or more. The inorganic oxide vapor deposition layer (B) may be a vapor deposition layer consisting only of at least one selected from the group consisting of aluminum oxide and silicon oxide, or may be a vapor deposition layer consisting only of silicon oxide.

[0040] The average thickness of the inorganic oxide vapor deposition layer (B) is preferably 200 nm or less, more preferably 100 nm or less, still more preferably 80 nm or less, and particularly preferably 60 nm or less. Also, the average thickness of the inorganic oxide vapor deposition layer (B) is preferably 10 nm or more, more preferably 20 nm or more, still more preferably 30 nm or more, even more preferably 35 nm or more, and particularly preferably 40 nm or more. The average thickness of the inorganic oxide vapor deposition layer (B) is the average value of the thicknesses at any 10 points of the cross-section of the inorganic oxide vapor deposition layer measured by an electron microscope.

[0041] The method for forming the inorganic oxide vapor deposition layer (B) is not particularly limited and can be formed by known physical vapor deposition methods or chemical vapor deposition methods. Specifically, vacuum vapor deposition method, sputtering method, ion plating method, ion beam mixing method, plasma CVD method, laser CVD method, MO-CVD method, thermal CVD method, etc. can be mentioned. It is preferable to use a physical vapor deposition method, and among them, it is particularly preferable to use the vacuum vapor deposition method.

[0042] When forming the inorganic oxide vapor deposition layer (B) on the barrier layer (A), the upper limit of the surface temperature of the barrier layer (A) is preferably 60 °C, more preferably 55 °C, and still more preferably 50 °C. Also, the lower limit of the surface temperature of the substrate during vapor deposition is not particularly limited, but 0 °C is preferable, 10 °C is more preferable, and 20 °C is still more preferable. Before performing the vapor deposition, the surface of the barrier layer (A) may be subjected to plasma treatment. Known methods can be used for the plasma treatment, and atmospheric pressure plasma treatment is preferable. In the atmospheric pressure plasma treatment, nitrogen, helium, neon, argon, krypton, xenon, radon, etc. are used as the discharge gas. Among them, nitrogen, helium, and argon are preferably used, and particularly nitrogen is preferable because the cost can be reduced.

[0043] When the inorganic oxide vapor deposition layer (B) contains aluminum oxide as a main component, it has a protective layer (F) directly laminated on the inorganic oxide vapor deposition layer (B). By providing the protective layer (F), even when the inorganic oxide vapor deposition layer (B) contains aluminum oxide as a main component, it is possible to suppress a decrease in adhesion strength and a decrease in gas barrier properties after storing the product of the present invention. Note that even when the inorganic oxide vapor deposition layer (B) contains silicon oxide as a main component, it may have a protective layer (F) directly laminated on the inorganic oxide vapor deposition layer (B).

[0044] [Protective layer (F)] The protective layer (F) may be composed of a composition containing at least one metal compound selected from the group consisting of metal alkoxides, hydrolysis products of metal alkoxides, and hydrolysis condensates of metal alkoxides, and a water-soluble resin. The metal alkoxide is preferably represented by the general formula: R 1 n M(OR 2 ) m (wherein M is a metal atom, R 1 , R 2 are organic groups having 1 to 8 carbon atoms, n is 0 or more, m is an integer of 1 or more, and n + m represents the valence of M). In the above general formula: R 1 n M(OR 2 ) m , as the metal atom represented by M, silicon, zirconium, titanium, aluminum, etc. can be used, and silicon is preferred. These metal alkoxides can also be used alone or by mixing alkoxides of two or more different metal atoms in the same solution.

[0045] Specific examples of the organic group R 1 include, for example, alkyl groups such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, n-hexyl group, n-octyl group, etc. Also, the organic group R 2Specific examples thereof include, for example, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a sec-butyl group, etc. These alkyl groups in the same molecule may be the same or different.

[0046] Among metal alkoxides, alkoxysilanes in which M in the above general formula is silicon (Si) are preferred. The alkoxysilane is represented by Si(ORa)4, and Ra is a lower alkyl group. As Ra, a methyl group, an ethyl group, an n-propyl group, an n-butyl group, etc. are used. Specific examples of the alkoxysilane include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, etc. Further, an alkylalkoxysilane Rb n Si(ORc) 4-n can be used (n is an integer of 1, 2, or 3). As Rb and Rc, a methyl group, an ethyl group, etc. are used. Specific examples of the alkylalkoxysilane include methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, etc. These alkoxysilanes and alkylalkoxysilanes can be used alone or in a mixture of two or more. Furthermore, condensates of alkoxysilanes can also be used, specifically, polytetramethoxysilane, polytetraethoxysilane, etc.

[0047] Two or more of these alkoxides may be mixed and used. In particular, by mixing and using an alkoxysilane and a zirconium alkoxide, the toughness, heat resistance, etc. of the resulting protective layer (F) may be improved. In the present invention, a silane coupling agent may be used in combination with the above alkoxide. As the silane coupling agent, a known organoalkoxysilane containing an organic reactive group can be used. In particular, an organoalkoxysilane having an epoxy group or an amino group is preferable. Examples thereof include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-aminopropyltrimethoxysilane, and γ-aminopropyltriethoxysilane. Two or more of such silane coupling agents may be mixed and used. The amount of such a silane coupling agent used is in the range of 0.1 to 20 parts by mass with respect to 100 parts by mass of the above alkoxysilane.

[0048] Examples of the water-soluble resin include resins having a hydroxyl group such as polyvinyl alcohol and poly(2-hydroxyethyl methacrylate), resins having a carboxyl group such as polyacrylic acid and carboxymethyl cellulose, resins having an amino group such as polyallylamine and polyethyleneimine, resins having an amide group such as polyacrylamide, poly(N,N-dimethylacrylamide) and poly(N-isopropylacrylamide), resins having a sulfonic acid group such as polystyrene sulfonic acid and polyvinyl sulfonic acid, resins having a polyether group such as polyethylene oxide and polyethylene glycol, and polyvinyl pyrrolidone, polyoxazoline, etc. Among the above-mentioned water-soluble resins, a resin having a hydrogen bonding group is preferable, a resin having a hydroxyl group, a resin having an amide group, a resin having a polyether group, polyvinyl pyrrolidone, polyoxazoline, etc. are more preferable, a resin having a hydroxyl group is further preferable, and a vinyl alcohol-based resin is particularly preferable. The vinyl alcohol-based resin may be polyvinyl alcohol or a copolymer containing vinyl alcohol units such as an ethylene-vinyl alcohol copolymer, but polyvinyl alcohol is preferable. These may be used alone or in combination of two or more.

[0049] The polyvinyl alcohol may be a homopolymer of vinyl alcohol or a copolymer containing other monomer units. From the viewpoint of gas barrier properties, the higher the degree of saponification is closer to 100 mol%, the better. Usually, it is 90 mol% or more, preferably 95 mol% or more. The number average degree of polymerization is usually 50 or more and 5000 or less.

[0050] In the composition for forming the protective layer (F), the mass ratio of at least one metal compound selected from the group consisting of metal alkoxides, hydrolyzates of metal alkoxides, and hydrolytic condensates of metal alkoxides to the water-soluble resin is preferably 10 / 90 to 50 / 50, more preferably 15 / 85 to 45 / 55, and even more preferably 25 / 75 to 35 / 65. When a resin composition of a hydrolytic condensate of a metal alkoxide and a water-soluble resin is used as the protective layer (F), it is particularly preferable that it is a resin composition containing a hydrolytic condensate of a silane alkoxide and polyvinyl alcohol.

[0051] When the protective layer (F) is a layer composed of the above resin composition, the proportion of the total mass of the metal compound and the water-soluble resin in the protective layer (F) is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more. The protective layer (F) may consist essentially of only the metal compound and the water-soluble resin, and may be 100% by mass or less.

[0052] In the present invention, the protective layer (F) composed of the above composition is specifically laminated as follows, for example. First, a coating liquid is prepared by mixing a metal alkoxide, a water-soluble resin, a sol-gel method catalyst, an acid, water, an organic solvent, and the like. Here, the hydrolysis and polycondensation reactions of the metal alkoxide gradually proceed in the above coating liquid. Next, the above coating liquid can be laminated by applying and drying it on the surface side of the inorganic oxide vapor deposition layer (B) by a conventional method.

[0053] From the viewpoints of gas barrier property, recyclability, and economy, the average thickness of the protective layer (F) is preferably 0.05 μm or more and 10 μm or less. More preferably, the average thickness of the protective layer (F) is 0.2 μm or more and 5 μm or less, and even more preferably 0.5 μm or more and 3 μm or less.

[0054] [Heat-seal layer (E)] The multilayer structure in the product of the present invention has a heat-seal layer (E) containing a polyolefin resin (e) as a main component and located on the outermost surface on the inner surface side of the package. As the polyolefin resin (e) contained as a main component in the heat-seal layer (E), those similar to the embodiments described for the polyolefin resin (d) to be described later can be used, and the preferred embodiments are also the same as those described for the polyolefin layer (D) to be described later.

[0055] In the resin constituting the heat-seal layer (E), the proportion of the polyolefin resin (e) is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, still more preferably 90% by mass or more, particularly preferably 95% by mass or more, and may be 98% by mass or more or 99% by mass or more. The resin constituting the heat-seal layer (E) may be composed only of the polyolefin resin (e) and may be 100% by mass or less.

[0056] The heat-seal layer (E) may be an undrawn layer or a drawn layer, but from the viewpoint of good heat-sealability, the heat-seal layer (E) is preferably an undrawn layer.

[0057] As the lower limit of the average thickness of the heat-sealing layer (E), 5 μm is preferable, 7 μm is more preferable, 10 μm is even more preferable, 20 μm is even more preferably, 25 μm is particularly preferable, and it may be 30 μm or 40 μm. When the average thickness of the heat-sealing layer (E) is equal to or greater than the above lower limit, even after storing the product of the present invention, the decrease in adhesion strength and the decrease in barrier properties tend to be more suppressed. As the upper limit of the average thickness of the heat-sealing layer (E), 200 μm is preferable, 100 μm is more preferable, and 70 μm is even more preferable. By the average thickness of the heat-sealing layer (E) being equal to or less than the above upper limit, it is possible to achieve thinning of the multilayer structure and the like.

[0058] The heat-sealing layer (E) may be composed of a single layer or may be composed of a plurality of layers.

[0059] As a method for laminating the heat-sealing layer (E), a known method can be used, and examples thereof include a coextrusion method, an extrusion coating method, a lamination method, and the like. When using the lamination method, an adhesive layer (G) described later may be provided.

[0060] The multilayer structure in the product of the present invention includes an adhesive layer (C) containing an adhesive resin (c) as a main component and a polyolefin layer (D) containing a polyolefin resin (d) as a main component, and may be a multilayer structure having a layer configuration in which an inorganic oxide vapor deposition layer (B), a barrier layer (A), an adhesive layer (C), and a polyolefin layer (D) are laminated in this order. Other layers (for example, an adhesive layer described later) may be provided between the layers, but the inorganic oxide vapor deposition layer (B) and the barrier layer (A) need to be directly laminated. Further, it is preferable to have a configuration in which the inorganic oxide vapor deposition layer (B), the barrier layer (A), the adhesive layer (C), and the polyolefin layer (D) are directly laminated in this order. By the multilayer structure having such a layer configuration, even after storing the product of the present invention, it is possible to more suppress the deterioration of the appearance of the package, the decrease in adhesion strength, and the decrease in barrier properties, and the recyclability of the package tends to be improved.

[0061] [Adhesive layer (C)] In the multilayer structure of the product of the present invention, from the viewpoint of obtaining a multilayer structure with excellent appearance, it may have an adhesive layer (C) containing an adhesive resin (c) as a main component. As the adhesive resin (c), an acid-modified polyolefin is preferable from the viewpoints of interlayer adhesiveness and recyclability, and a carboxylic acid-modified polyolefin resin obtained by graft-polymerizing an unsaturated carboxylic acid such as maleic anhydride or its derivative to a polyolefin resin is more preferable. The melting point of the adhesive resin (c) mainly depends on the polyolefin resin before acid modification. Regarding the polyolefin resin, the content described for the polyolefin resin (d) described later can be applied as it is. The adhesive resin (c) is preferably acid-modified polyethylene or acid-modified polypropylene, and more preferably acid-modified polypropylene.

[0062] The proportion of the acid-modified polyolefin resin in the adhesive resin (c) is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 95% by mass or more, and may be substantially composed only of the acid-modified polyolefin resin, may be composed only of the acid-modified polyolefin resin, and may be 100% by mass or less. Further, the proportion of the adhesive resin (c) in the adhesive layer (C) is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 95% by mass or more, and may be 97% by mass or more, may be 99% by mass or more, may be substantially composed only of the adhesive resin (c), and may be 100% by mass or less.

[0063] [Polyolefin layer (D)] From the viewpoints of enhancing the water vapor barrier property, flex resistance, and recyclability of the product of the present invention, and suppressing the decrease in the adhesion strength and barrier property of the package after storing the product of the present invention, the multilayer structure in the product of the present invention may have a polyolefin layer (D) containing a polyolefin resin (d) as a main component. Here, the polyolefin layer (D) means a polyolefin layer containing a polyolefin resin (d) as a main component in a layer other than the heat seal layer (E). In other words, it means a layer other than the outermost layer on the inner surface side and containing a polyolefin resin (d) as a main component.

[0064] Examples of the polyolefin resin (d) include olefins such as polyethylene (linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, etc.), ethylene-propylene copolymer, polypropylene, propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer, polybutene, and polypentene, either alone or as a copolymer thereof. Among them, polyethylene or polypropylene is more preferable, and polypropylene is even more preferable. One kind or two or more kinds of polyolefins can be used.

[0065] The content of the polyolefin resin (d) in the resin constituting the polyolefin layer (D) is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 97% by mass or more, and may be 99% by mass or more. The resin constituting the polyolefin layer (D) may be composed only of the polyolefin resin (d) and may be 100% by mass or less.

[0066] The polyolefin layer (D) may be an unstretched layer or a stretched layer. However, from the viewpoint of further suppressing the decrease in the adhesion strength and barrier property when storing the content containing sodium chloride, it is preferably stretched in at least one axial direction, and more preferably stretched in both axial directions.

[0067] In the multilayer structure of the product of the present invention, the polyolefin layer (D) may be provided on the outermost layer on the side opposite to the heat-sealing layer (E). When the polyolefin layer (D) is provided as the outermost layer, from the viewpoint of increasing the melting point difference from the heat-sealing layer (E) to improve the heat-sealing property, the polyolefin layer (D) is preferably a stretched layer.

[0068] The multilayer structure in the product of the present invention may have a layer structure in which an inorganic oxide vapor deposition layer (B), a barrier layer (A), an adhesive layer (C), a polyolefin layer (D), and a heat-sealing layer (E) are laminated in this order. Also, other layers (for example, an adhesive layer described later) may be provided between the layers of each layer other than the inorganic oxide vapor deposition layer (B) and the barrier layer (A), but it is preferable to have a layer structure in which the inorganic oxide vapor deposition layer (B), the barrier layer (A), the adhesive layer (C), the polyolefin layer (D), and the heat-sealing layer (E) are directly laminated in this order. When the polyolefin layer (D) and the heat-sealing layer (E) are laminated in this order, from the viewpoint of further suppressing a decrease in adhesion strength and a decrease in barrier properties, the polyolefin layer (D) is preferably stretched at least in one axial direction, and more preferably stretched in two axial directions.

[0069] As the lower limit of the average thickness per layer of the polyolefin layer (D), 1 μm is preferable, and 3 μm is more preferable. When the average thickness per layer of the polyolefin layer (D) is equal to or greater than the above lower limit, the recyclability becomes better, and sufficient moisture-proof property and the like can be achieved. As the upper limit of the average thickness per layer of the polyolefin layer (D), 100 μm is preferable, 50 μm is more preferable, 40 μm is further preferable, and 30 μm may also be acceptable. When the average thickness per layer of the polyolefin layer (D) is equal to or less than the above upper limit, the vapor-deposited film can be made thinner.

[0070] As the lower limit of the total average thickness of the polyolefin layer (D), 1 μm is preferable, and 3 μm is more preferable. As the upper limit of the total average thickness of the polyolefin layer (D), 200 μm is preferable, 100 μm is more preferable, 80 μm is further preferable, and 50 μm is particularly preferable.

[0071] The polyolefin layer (D) may consist of a single layer or a plurality of layers.

[0072] The adhesive layer (C), the polyolefin layer (D), and the heat-sealing layer (E) may contain other components such as antioxidants, plasticizers, heat stabilizers (melt stabilizers), photoinitiators, deodorants, ultraviolet absorbers, antistatic agents, lubricants, colorants, fillers, desiccants, fillers, pigments, dyes, processing aids, flame retardants, antifogging agents, etc., as long as the effects of the present invention are not impaired. However, the total amount is less than 50% by mass for each layer, preferably less than 40% by mass, more preferably less than 30% by mass, further preferably less than 20% by mass, particularly preferably less than 10% by mass, and may be less than 5% by mass, less than 3% by mass, or less than 1% by mass.

[0073] It is preferable that the barrier layer (A), the adhesive layer (C), and the polyolefin layer (D) are stretched at least in one axial direction, and more preferably in two axial directions. In such a case, it is possible to suppress a decrease in the adhesion strength of the package after the storage test and a decrease in the gas barrier properties after the storage test. When the barrier layer (A), the adhesive layer (C), and the polyolefin layer (D) are uniaxially stretched, for example, it is preferable that they are stretched 2 times or more and less than 12 times in the uniaxial direction, and more preferably 3 times or more and less than 6 times in the uniaxial direction. When the barrier layer (A), the adhesive layer (C), and the polyolefin layer (D) are biaxially stretched, it is preferable that they are stretched 2 times or more and less than 15 times in the longitudinal axis direction and 2 times or more and less than 15 times in the transverse axis direction, and they may be stretched 2 times or more and less than 6 times in the longitudinal axis direction and 2 times or more and less than 6 times in the transverse axis direction.

[0074] The barrier layer (A), the adhesive layer (C), and the polyolefin layer (D) are preferably stretched integrally. For example, the barrier layer (A), the adhesive layer (C), and the polyolefin layer (D) may be formed as a multilayer film laminated in this order and stretched. The method for forming the multilayer film is not particularly limited, but generally, a conventional coextrusion method in which each resin is extruded from a separate die or a common die and laminated can be used. As the die, either an annular die or a T-die can be used. The method of stretching in the uniaxial direction or the biaxial direction is also not particularly limited, and the film can be manufactured by stretching in the flow direction of the film and / or in a direction perpendicular to the flow direction, that is, the width direction, by a conventionally known stretching method such as roll-type uniaxial stretching, tenter-type uniaxial stretching, tubular simultaneous biaxial stretching, tenter-type sequential biaxial stretching, tenter-type simultaneous biaxial stretching, etc. Also, for the tenter-type sequential biaxial stretching, both axes may use the tenter-type, or it may be a combination of roll-type stretching and tenter-type stretching. Among them, the effects of the present invention are particularly remarkable in the case of a multilayer film manufactured by tenter-type sequential biaxial stretching, which is a combination of roll-type stretching and tenter-type stretching. The temperature during stretching is usually 40 to 170°C, more preferably 50 to 160°C, from the viewpoint of processability. If necessary, after the stretching treatment, it is preferable to perform a so-called heat fixing operation by heating at a temperature above the glass transition point and below the melting point to increase the crystallinity and fix the orientation of the molecular chains.

[0075] The manufacturing method of the multilayer film including the barrier layer (A), the adhesive layer (C) and the polyolefin layer (D) is not particularly limited, but the coextrusion method is preferable. That is, it is preferably a coextruded film. The film forming method of the coextruded film is not particularly limited, but generally it is formed by a melt molding method in which melt extrusion is performed by an extruder. By forming the multilayer film including the barrier layer (A), the adhesive layer (C) and the polyolefin layer (D) by the coextrusion method, it is not necessary to provide an adhesive layer (G) etc. described later between the layers, and thus the recyclability of the obtained multilayer structure tends to be further enhanced. That is, the barrier layer (A), the adhesive layer (C) and the polyolefin layer (D) are preferably a coextruded film having a structure directly laminated in this order. Further, a multilayer structure obtained by using a multilayer film in which the barrier layer (A), the adhesive layer (C) and the heat seal layer (E) are formed by the coextrusion method is also a preferred embodiment.

[0076] [Adhesive layer (G)] The multilayer structure in the product of the present invention may have an adhesive layer (G) containing an adhesive (g) as a main component. The adhesive layer can be formed by applying a known adhesive (g) and drying it. As the adhesive (g), a known adhesive used as an adhesive for dry lamination is preferably used. For example, a two-component reaction type polyurethane-based adhesive in which a polyisocyanate component and a polyol component are mixed and reacted is preferable. The proportion of the adhesive (g) in the adhesive layer (G) is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more. The adhesive layer (G) may be a layer composed only of the adhesive (g), and may be 100% by mass or less.

[0077] From the perspective of recyclability, the total average thickness of the adhesive layer (G) is preferably 10 μm or less, and may be 6 μm or less, or even 3 μm or less. The total average thickness of the adhesive layer (G) may also be 1 μm or more. When the multilayer structure in the product of the present invention has an adhesive layer (G), the adhesive layer (G) is preferably provided between the inorganic oxide vapor deposition layer (B) and the heat seal layer (E), between the polyolefin layer (D) and the heat seal layer (E), or between the inorganic oxide vapor deposition layer (B) and the polyolefin layer (D).

[0078] [Multilayer structure] The multilayer structure in the product of the present invention has a barrier layer (A), an inorganic oxide vapor deposition layer (B), and a heat seal layer (E), and has a layer structure in which the barrier layer (A) and the inorganic oxide vapor deposition layer (B) are directly laminated. By having such a configuration, the multilayer structure tends to suppress the deterioration of the appearance, the decrease in adhesion strength, and the decrease in barrier properties of the product of the present invention after storage.

[0079] From the perspective of further improving recyclability, the ratio of the average thickness of the barrier layer (A) to the average thickness of the multilayer structure is preferably 5% or less, more preferably 3% or less, and even more preferably 2% or less. The above ratio may also be 0.1% or more.

[0080] From the perspective of further improving recyclability, the ratio of the average thickness of the layer containing a polyolefin-based resin as the main component to the average thickness of the multilayer structure is preferably 80% or more, more preferably 85% or more, even more preferably 90% or more, and particularly preferably 95% or more. The above ratio may also be 99.9% or less.

[0081] From the perspective of enhancing the mechanical strength of the multilayer structure, the average thickness of the multilayer structure is preferably 20 μm or more, and may be 30 μm or more, or even 40 μm or more. Also, from the perspective of heat sealability, the average thickness of the multilayer structure is preferably 400 μm or less, and may be 300 μm or less, 200 μm or less, or even 100 μm or less.

[0082] The multilayer structure is not particularly limited, and examples thereof include the following layer configurations. In the following layer configurations, the barrier layer (A) is represented as A, the inorganic oxide vapor deposition layer (B) as B, the heat seal layer (E) as E, the protective layer (F) as F, the adhesive layer (C) as C, and the polyolefin layer (D) as D. " / " means directly laminated, and " / / " means laminated via an adhesive layer or directly laminated, but preferably means laminated via an adhesive layer. (1) A / B / / E (2) A / B / F / / E (3) B / A / / E (4) F / B / A / / E (5) D / / B / A / / E (6) D / / F / B / A / / E (7) B / A / C / E (8) F / B / A / C / E (9) D / / B / A / C / E (10) D / / F / B / A / C / E (11) B / A / C / D / E (12) F / B / A / C / D / E (13) D / / B / A / C / D / E (14) D / / F / B / A / C / D / E (15) B / A / C / D / / E (16) F / B / A / C / D / / E (17) D / / B / A / C / D / / E (18) D / / F / B / A / C / D / / E (19) D / C / A / B / / E (20) D / C / A / B / F / / E Among them, D / C / A / B / / E, D / C / A / B / F / / E, B / A / C / D / / E or A / B / / E is preferable from the viewpoint of maintaining industrial productivity and recyclability while further suppressing a decrease in adhesion strength and a decrease in barrier properties when storing contents containing sodium chloride. D / C / A / B / / E and D / C / A / B / F / / E are more preferable, and D / C / A / B / / E is even more preferable.

[0083] From the viewpoint of improving recyclability, it is preferable that the multilayer structure does not have a metal layer with a thickness of 1 μm or more.

[0084] In the multilayer structure, it is preferable from the viewpoint of enhancing recyclability that the resins that are the main components of the polyolefin layer (D) and the heat-sealing layer (E) are of the same resin type. Here, the same resin type means that, for example, when the resin contained as the main component in the heat-sealing layer (E) is polypropylene, the resin contained as the main component in the polyolefin layer (D) is also polypropylene. Further, in the multilayer structure, it is also preferable from the viewpoint of enhancing recyclability that the resins that are the main components of the adhesive layer (C), the polyolefin layer (D), and the heat-sealing layer (E) are of the same resin type. For example, when the resin contained as the main component in the heat-sealing layer (E) is polypropylene, it is preferable that the adhesive layer (C) is an acid-modified polypropylene resin.

[0085] The multilayer structure of the present invention may have other layers other than those described above as long as the effects of the present invention are not inhibited. Examples of other layers include a printing layer. The printing layer may be included at any position of the multilayer structure of the present invention, but it is preferably located on at least one surface of the outer layer. Examples of the printing layer include a film obtained by coating and drying a solution containing, for example, a pigment or a dye and, if necessary, a binder resin. Examples of the coating method for the printing layer include various coating methods using a gravure printing method, a wire bar, a spin coater, a die coater, etc. The thickness of the ink layer is not particularly limited, but is preferably 0.5 to 10 μm, more preferably 1 to 4 μm.

[0086] The oxygen transmission rate measured under the conditions of 20°C and 65% RH according to the method described in ISO21309-2 Annex C (2019) of the multilayer structure is preferably 10 cc / (m 2 ·day·atm) or less, more preferably 5 cc / (m 2 ·day·atm) or less, even more preferably 1 cc / (m 2 ·day·atm) or less, and still more preferably 0.5 cc / (m 2It is particularly preferable that it is below ·day·atm).

[0087] The oxygen transmission rate measured under the conditions of 43°C and 50% RH for 200 days and then measured according to the method described in ISO 21309-2 Annex C (2019) of the multilayer structure, measured under the conditions of 20°C and 65% RH, is 10 cc / (m 2 ·day·atm) or less is preferable, 5 cc / (m 2 ·day·atm) or less is more preferable, 1 cc / (m 2 ·day·atm) or less is even more preferable, 0.5 cc / (m 2 ·day·atm) or less is particularly preferable. Note that the specific measurement of the oxygen transmission rate after the storage test can be measured by the method described in the examples.

[0088] The water vapor transmission rate measured according to ISO 15106-2 (2003) of the multilayer structure, measured under the conditions of 40°C and 90 / 0% RH, is 10 g / (m 2 ·day) or less is preferable, 5 g / (m 2 ·day) or less is more preferable, 1 g / (m 2 ·day) or less is even more preferable, 0.5 g / (m 2 ·day) or less is particularly preferable.

[0089] The water vapor transmission rate measured under the conditions of 43°C and 50% RH for 200 days and then measured according to the method described in ISO 15106-2 (2003) of the multilayer structure, measured under the conditions of 40°C and 90 / 0% RH, is 10 g / (m 2 ·day) or less is preferable, 5 g / (m 2 ·day) or less is more preferable, 1 g / (m 2 ·day) or less is even more preferable, 0.5 g / (m 2 ·day) or less is particularly preferable. Note that the specific measurement of the water vapor transmission rate after the storage test can be measured by the method described in the examples.

[0090] [Package] The package in the product of the present invention includes the multilayer structure and has a heat-sealing layer (E) on the inner surface side. Preferably, the package is obtained by heat-sealing the heat-sealing layers (E) of the multilayer structure to each other. The package is used for packaging purposes, and its shape is not limited. The package may be in the form of a sheet or may be formed into a predetermined shape such as a bag shape.

[0091] The package is formed into various forms according to the application, such as a vertical bag-making filling and sealing bag, a pouch with a spout, a laminated tube container, a lid material for a container, etc.

[0092] The product of the present invention has a content with 1.0% by mass or more of sodium chloride inside the package. When the content has 1.0% by mass or more of sodium chloride, using a multilayer structure having an aluminum vapor deposition layer tends to promote the deterioration of the aluminum vapor deposition layer, resulting in deterioration of the appearance and a decrease in the adhesion strength, and may induce deterioration of the barrier properties. However, by using the multilayer structure, it tends to be possible to suppress the deterioration of the appearance, the decrease in the adhesion strength, and the decrease in the barrier properties.

[0093] The content of sodium chloride in the content is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 2.5% by mass or less. When the amount of sodium chloride is 5% by mass or less, it tends to be possible to suppress the decrease in the barrier properties after storage of the product. The content of sodium chloride in the content may be 1.5% by mass or more. When the content of sodium chloride in the content is 1.0% by mass or more, the problems of the present invention become prominent, and the effect of suppressing the decrease in the barrier properties by the multilayer structure in the product of the present invention becomes prominent.

[0094] As the content, it is preferable that the content contains moisture because the problems of the present invention become more prominent. When the content contains moisture, the content may be 1% by mass or more or 5% by mass or more. When the content contains moisture, it is preferably 70% by mass or less, and more preferably 60% by mass or less.

[0095] Examples of the content containing moisture include dairy products such as cheese, fats and oils such as butter and margarine, spices such as wasabi and mustard, seasonings such as sauces, ketchup and mayonnaise, and the like. These may be in a liquid state, a paste state, or a solid state.

[0096] Also, it is preferable that the content contains lipids because the problems of the present invention become more prominent. When the content contains lipids, the content is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less. When the content contains lipids, it may be 50% by mass or more or 60% by mass or more.

[0097] Examples of the lipid include monoglyceride, diglyceride, triglyceride, free fatty acid (oleic acid), sterol, and the like. Among them, triglyceride is more preferable. The lipid may contain one kind or two or more kinds.

[0098] Furthermore, it is preferable that the content is an acidic food because the problems of the present invention become more prominent. When the content is an acidic food, its pH is preferably 6.0 or less, more preferably 5.0 or less, and even more preferably 4.0 or less. When the content is an acidic food, its pH is preferably 1.0 or more, more preferably 2.0 or more.

[0099] Even if the product of the present invention contains a content containing 1.0% by mass or more of sodium chloride, it can maintain its appearance, adhesion strength, and barrier properties over a long period of time. Also, even when the content contains moisture or lipids, the same effects can be exhibited. Furthermore, even when the content is an acidic food, the same effects can be exhibited.

Examples

[0100] Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples at all.

[0101] [Evaluation Method] (1) Storage Test The pouches (15 cm square size) obtained in the examples and comparative examples were stored for 200 days under the conditions of 43°C and 50% RH using a thermo-hygrostat (Thermo-hygrostat "PR-3J" manufactured by Espec Corporation). After 200 days of storage, the contents were removed from inside the pouch, the pouch was washed with water, moisture etc. were wiped off, and it was used as a sample for the following evaluation.

[0102] (1-1) Oxygen transmission rate (OTR) after storage test (1) Regarding the evaluation sample (pouch) obtained in (1), a 50 cm circle was cut out from the center part of the pouch and conditioned for 1 week under the conditions of 20°C and 65% RH. Then, it was installed in a measuring device such that the outer layer side was the oxygen supply side and the sealant layer (E) side was the carrier gas side, and the oxygen transmission rate was measured. Specifically, 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, a pressure of 1 atm on the oxygen supply side, and a carrier gas pressure of 1 atm, in accordance with the method described in ISO21309-2 Annex C (2019), the oxygen transmission rate (unit: cc / (m 2 ·day·atm)) was measured and evaluated according to the following criteria. As the carrier gas, nitrogen gas containing 2% by volume of hydrogen gas was used. It was judged that the decrease in gas barrier properties could not be suppressed for D determination. 2 ·day·atm)) was measured and evaluated according to the following criteria. As the carrier gas, nitrogen gas containing 2% by volume of hydrogen gas was used. It was judged that the decrease in gas barrier properties could not be suppressed for D determination. Judgment: Criteria A: 0.1 cc / (m 2 ·day·atm) or more and less than 0.5 cc / (m 2 ·day·atm) B: 0.5 cc / (m 2 ·day·atm) or more and less than 1 cc / (m 2 ·day·atm) C: 1 cc / (m 2 ·day·atm) or more and less than 10 cc / (m 2 ·day·atm) D: 10 cc / (m 2 ·day·atm) or more

[0103] (1-2) WVTR (water vapor transmission rate) after storage test Regarding the evaluation sample (pouch) obtained in (1), a 50-cm circular cut was made from the center of the pouch. 2 After that, one side was placed on the water vapor supply side and the other side on the carrier gas side of the measuring device, and the water vapor transmission rate was measured. Specifically, using a water vapor transmission rate measuring device ("MOCON PERMATRAN W3 / 33" manufactured by Modern Controls), in accordance with JIS K 7129-2 (infrared sensor method; 2019), under the conditions of a temperature of 40 °C, a humidity of 90% RH on the water vapor supply side, and a humidity of 0% RH on the carrier gas side, in accordance with the method described in ISO15106-2 (2003), the water vapor transmission rate (unit: g / (m 2 ·day)) was measured. Nitrogen gas was used as the carrier gas. It was determined that the D determination could not suppress the decrease in water vapor barrier properties. Determination: Criteria A: 0.1 g / (m 2 ·day) or more and less than 0.5 g / (m 2 ·day) B: 0.5 g / (m 2 ·day) or more and less than 1 g / (m 2 ·day) C: 1 g / (m 2 ·day) or more and less than 10 g / (m 2 ·day) D: 10 g / (m 2 ·day) or more

[0104] (1-3) Adhesion strength after the storage test The evaluation sample obtained in (1) was cut into strips of 100 mm × 15 mm, conditioned at 23 °C and 50% RH for 24 hours, and then, under the same conditions, a T-peel test was performed 5 times with a tensile speed of 10 mm / min using a tensile testing machine ("AUTOGRAPH AGS-H" manufactured by Shimadzu Corporation). The average value of the obtained measured values was taken as the adhesion strength. When the adhesion strength was 1.0 N or less, it was determined that the decrease in adhesion strength could not be suppressed. In addition, in all measurements, it was confirmed that peeling occurred at the inorganic oxide vapor deposition layer (B) layer or the layer in contact with the inorganic oxide vapor deposition layer (B).

[0105] (1-4) Appearance after the storage test The evaluation samples obtained in (1) were visually inspected. Evaluation samples with almost no visible change in appearance compared to before storage were designated as A, and evaluation samples with whitening observed compared to before storage were designated as B. When the evaluation was B, it was judged that the deterioration of the appearance could not be suppressed.

[0106] (2) Recyclability The multilayer structures obtained in the examples and comparative examples were crushed into sizes of 4 mm square or less. This crushed material and polypropylene resin (PP1) were dry-blended at a mass ratio (crushed material / PP1) of 20 / 80, and a single-layer film with an average thickness of 20 μm was obtained by performing single-layer film formation under the following extrusion conditions. Also, as a control, a single-layer control film with an average thickness of 20 μm was obtained using only polypropylene resin (PP1). Extruder: Single-screw extruder manufactured by Toyo Seiki Seisakusho Screw diameter: 20 mm φ (L / D = 20, compression ratio = 3.5, full flight type) Extrusion temperature: C1 / C2 / C3 / D = 190 / 230 / 230 / 230 °C Take-up roll temperature: 80 °C The obtained single-layer film and the control single-layer film were visually compared and evaluated according to the following criteria. A D judgment was made that the recyclability was poor. Judgment: Criteria A: The amount of lumps was almost unchanged compared to the control. B: The amount of lumps less than 0.5 mm was slightly more than that of the control. C: The amount of lumps less than 0.5 mm was 30% or more more than that of the control. D: The amount of lumps larger than 0.5 mm was 30% or more more than that of the control.

[0107] [Materials used] EVOH1: EVOH (ethylene content 48 mol%, saponification degree 99.9 mol%, MFR (210 °C, 2.16 kg load) 14.8 g / 10 min) PET: PET film ("FE2001" manufactured by Futamura Chemical Co., Ltd., average thickness 12 μm) MAhPE: Maleic Anhydride Modified PE (manufactured by Mitsui Chemicals, Inc., "Admer (trademark) NF518", MFR (at 190 °C, under a load of 2.16 kg) 2.4 g / 10 min) MAhPP: Maleic Anhydride Modified PP (manufactured by Mitsui Chemicals, Inc., "Admer (trademark) QF500", MFR (at 230 °C, under a load of 2.16 kg) 3.0 g / 10 min) PP1: PP (manufactured by Japan Polypropylene Corporation, "Novatech (trademark) PP EA7AD", density 0.90 g / cc, MFR (at 230 °C, under a load of 2.16 kg) 1.4 g / 10 min). When biaxially stretched in the examples, it was denoted as BOPP1, and when unstretched, it was denoted as CPP1. PE: LDPE (manufactured by Japan Polypropylene Corporation, "Novatech (trademark) LD LJ400", density 0.921 g / cc, MFR (at 190 °C, under a load of 2.16 kg) 1.5 g / 10 min)). When uniaxially stretched in the MD direction in the examples, it was denoted as MDOPE. BOPP2: Biaxially stretched PP film (manufactured by Toyobo Co., Ltd., "Pyren (trademark) Film OT P2161", thickness 20 μm) CPP2: Unstretched PP film (manufactured by Toppan Printing Co., Ltd., "RXC-22", average thickness 50 μm) CPP3: Film (average thickness 30 μm) made from PP (manufactured by Japan Polypropylene Corporation, "Novatech (trademark) PP FX4GF", density 0.90 g / cc, MFR (at 230 °C, under a load of 2.16 kg) 5.0 g / 10 min)) using a single-screw extruder (Plastic Engineering Laboratory Co., Ltd. GT-32-A) CPP4: Film (average thickness 10 μm) made from PP (manufactured by Japan Polypropylene Corporation, "Novatech (trademark) PP FX4GF", density 0.90 g / cc, MFR (at 230 °C, under a load of 2.16 kg) 5.0 g / 10 min)) using a single-screw extruder (Plastic Engineering Laboratory Co., Ltd. GT-32-A)

[0108] [Example 1] Using EVOH1 as the material for the barrier layer (A), MAhPP as the material for the adhesive layer (C), and PP1 as the material for the polyolefin layer (D), a three-layer coextruded film (A / C / D = EVOH1 / MAhPP / PP1 = 4.5 μm / 4.5 μm / 180 μm) was formed under the following conditions. Extruder for EVOH: Single-screw extruder (Tokyo Seiki Co., Ltd. Labo Machine ME type CO-EXT) Screw for EVOH: 20 mmφ in diameter, L / D 20, full-flight screw Extrusion temperature for EVOH: Feeding section / Compression section / Measuring section / Die = 175 / 210 / 220 / 230 °C Extruder for MAhPP: Single-screw extruder (Technovel Corporation SZW20GT-20MG-STD) Screw for MAhPP: 20 mmφ in diameter, L / D 20, full-flight screw Extrusion temperature for MAhPP: Feeding section / Compression section / Measuring section / Die = 150 / 200 / 220 / 230 °C Extruder for PP: Single-screw extruder (Plastic Engineering Laboratory Co., Ltd. GT-32-A) Screw for PP: 32 mmφ in diameter, L / D 28, full-flight screw Extrusion temperature for PP: Feeding section / Compression section / Measuring section / Die = 170 / 220 / 230 / 230 °C Die: 300 mm wide coat hanger die for three-layer three-species (manufactured by Plastic Engineering Laboratory Co., Ltd.)

[0109] The obtained coextruded film was stretched 3 times in the longitudinal direction and 3 times in the transverse direction at 160 °C using a tenter-type simultaneous biaxial stretching facility to obtain a biaxially stretched coextruded film (EVOH1 / MAhPP / BOPP1 = 0.5 μm / 0.5 μm / 20 μm).

[0110] On the surface of EVOH1 of the obtained biaxially stretched coextruded film, silicon oxide was vacuum-deposited by a known vacuum deposition method so that the average thickness was 50 nm, and a silicon oxide (silica) deposition layer SiOx with an average thickness of 50 nm was laminated to produce a deposited film (B / A / C / D = SiOx / EVOH1 / MAhPP / BOPP1 = 50 nm / 0.5 μm / 0.5 μm / 20 μm). Next, on one side of the unstretched polypropylene film (CPP2) prepared as the heat-sealing layer (E), a two-component adhesive ("Takelac (trademark) A-520" and "Takenate (trademark) A-50" manufactured by Mitsui Chemicals, Inc.) was applied and dried so that the average thickness after drying was 2 μm to form an adhesive layer (G) (tie), and a multilayer structure (D / C / A / B / G / E = BOPP1 / MAhPP / EVOH1 / SiOx / tie / CPP2 = 20 μm / 0.5 μm / 0.5 μm / 50 nm / 2 μm / 50 μm) was produced by laminating with the obtained deposited film. The recyclability of the obtained multilayer structure was evaluated according to the method described in the above evaluation method (2). The results are shown in Table 1.

[0111] After cutting out two sheets of the obtained multilayer structure into A4 size (210 mm × 297 mm), CPP2s were overlapped and heat-sealed on three sides to produce a three-sided bag. The three-sided bag was heat-sealed so that the length of one side was 15 cm, and unnecessary parts were cut off. Next, ketchup was prepared by mixing tomatoes, onions, vinegar, sugar, and salt. The obtained ketchup contained 1.9% by mass of sodium chloride, 60% by mass of water, and 10% by mass of lipids, and had a pH of 3.1. 50 g of the obtained ketchup was filled into the opening of the three-sided bag, and the opening was heat-sealed to produce a pouch (15 cm square size) filled with the contents. The obtained pouch was evaluated for OTR, WVTR, adhesion strength, and appearance after the storage test according to the method described in the above evaluation method (1). The results are shown in Table 1.

[0112] [Examples 2, 3, 5, 8 to 10, 14, Comparative Examples 1, 3] The multilayer structure and the pouch were produced and evaluated in the same manner as in Example 1, except that the type and average thickness of the inorganic oxide vapor deposition layer (B), the average thickness of the polyolefin layer (D), the type and average thickness of the sealant layer (E), and the composition of the ketchup as the content were changed as shown in Table 1. The results are shown in Table 1.

[0113] [Example 4] On each side of the biaxially stretched polypropylene film (BOPP2) and the unstretched polypropylene film (CPP4), a two-component adhesive (Take lacquer (trademark) A-520 and Take nate (trademark) A-50 manufactured by Mitsui Chemicals, Inc.) was applied and dried so that the average thickness after drying was 2 μm to form an adhesive layer (tie), and the vapor deposition film obtained in Example 1 was laminated to produce a multilayer structure (D / G / B / A / C / D / G / E = BOPP2 / tie / SiOx / EVOH1 / MAhPP / BOPP1 / tie / CPP4 = 20 μm / 2 μm / 50 nm / 0.5 μm / 0.5 μm / 20 μm / 2 μm / 10 μm). The pouch was produced and evaluated in the same manner as in Example 1, except that the obtained multilayer structure was used. The results are shown in Table 1.

[0114] [Example 6] The multilayer structure and the pouch were produced and evaluated in the same manner as in Example 1, except that a uniaxially stretched coextruded film produced under the following conditions was used instead of the biaxially stretched coextruded film. The results are shown in Table 1. Using EVOH1 as the material for the barrier layer (A), MAhPE as the material for the adhesive layer (C), and PE as the material for the polyolefin layer (D), a three-layer coextruded film (A / C / D = EVOH1 / MAhPE / PE = 10 μm / 10 μm / 100 μm) was formed under the following conditions. Extruder for EVOH: Single-screw extruder (Toyosha Laboratory Machine ME type CO-EXT) Screw for EVOH: 20 mmφ in diameter, L / D 20, full flight screw Extrusion temperature for EVOH: Feeding section / Compression section / Measuring section / Die = 175 / 210 / 220 / 230 °C Extruder for MAhPE: Single-screw extruder (Technovel Corporation, SZW20GT-20MG-STD) Screw for MAhPE: Diameter 20 mmφ, L / D 20, full-flight screw Extrusion temperature for MAhPP: Feeding section / Compression section / Metering section / Die = 170 / 190 / 210 / 230 °C Extruder for PE: Single-screw extruder (Plastic Engineering Laboratory, GT-32-A) Screw for PE: Diameter 32 mmφ, L / D 28, full-flight screw Extrusion temperature for PE: Feeding section / Compression section / Metering section / Die = 170 / 190 / 210 / 230 °C Die: 3-layer coat hanger die for 300 mm width (manufactured by Plastic Engineering Laboratory)

[0115] The obtained coextruded film was uniaxially stretched 5 times in the longitudinal direction (MD direction) at 115 °C by a uniaxial stretching device to obtain a uniaxially stretched coextruded film (EVOH1 / MAhPE / MDOPE = 2.0 μm / 2.0 μm / 20 μm).

[0116] [Example 7] A multilayer structure and a pouch were produced and evaluated in the same manner as in Example 1, except that mayonnaise, which was a mixture of cooking oil, vinegar, eggs, and salt, was used instead of ketchup as the content of the pouch. The results are shown in Table 1. The obtained mayonnaise contained 1.9% by mass of sodium chloride, 5% by mass of moisture, and 90% by mass of lipids, and had a pH of 4.0.

[0117] [Example 11] A multilayer structure and a pouch were produced and evaluated in the same manner as in Example 4, except that the average thickness per layer of the adhesive layer (tie) was adjusted to be as described in Table 1. The results are shown in Table 1.

[0118] [Example 12] EVOH1 was melted at 240 °C using a single-screw extruder and extruded from a die onto a casting roll while blowing air at a wind speed of 30 m / s using an air knife to obtain an unstretched film with an average thickness of 120 μm. The obtained unstretched film was brought into contact with warm water at 80 °C for 10 seconds and stretched 3.2 times in the longitudinal direction and 3.0 times in the transverse direction at 90 °C using a tenter-type simultaneous biaxial stretching facility, and further heat-treated in a tenter set at 170 °C for 5 seconds to obtain a biaxially stretched EVOH1 film with an average thickness of 12 μm.

[0119] On the surface of the obtained biaxially stretched EVOH1 film, silicon oxide was vacuum-deposited by a known vacuum deposition method so that the average thickness was 50 nm, and a vapor-deposited film (B / A = SiOx / EVOH1 = 50 nm / 12 μm) with a silicon oxide (silica) vapor-deposited layer SiOx with an average thickness of 50 nm laminated was produced. On each side of a biaxially stretched polypropylene film (BOPP2) prepared as the polyolefin layer (D) and an unstretched polypropylene film (CPP3) prepared as the heat-sealing layer (E), a two-component adhesive ("Takelac (trademark) A-520" and "Takeneate (trademark) A-50" manufactured by Mitsui Chemicals, Inc.) was applied and dried so that the average thickness after drying was 2 μm to form an adhesive layer (tie), and a multilayer structure (D / G / A / B / G / E = BOPP2 / tie / EVOH1 / SiOx / tie / CPP3 = 20 μm / 2 μm / 12 μm / 50 nm / 2 μm / 30 μm) was produced by laminating with the obtained vapor-deposited film. The pouch was produced and evaluated in the same manner as in Example 1 except that the obtained multilayer structure was used. The results are shown in Table 1.

[0120] [Example 13] The conditions were changed so that the average thickness of the coextruded film was EVOH1 / MAhPP / PP1 = 2.0 μm / 2.0 μm / 30 μm, and a multilayer structure and a pouch were produced and evaluated in the same manner as in Example 2 except that a vapor-deposited film was produced without stretching. The results are shown in Table 1.

[0121] [Example 15] On the surface of EVOH1 of the biaxially stretched coextruded film (EVOH1 / MAhPP / BOPP1 = 0.5 μm / 0.5 μm / 20 μm) obtained in Example 1, aluminum oxide was vacuum-deposited by a known vacuum deposition method so that the average thickness was 50 nm, and an alumina-deposited layer AlOx with an average thickness of 50 nm was laminated to produce a vapor-deposited film (B / A / C / D = AlOx / EVOH1 / MAhPP / BOPP1 = 50 nm / 0.5 μm / 0.5 μm / 20 μm). Next, 10.4 g of tetraethoxysilane was used as a metal alkoxide, 89.6 g of hydrochloric acid (0.1 N) was added, and the mixture was stirred for 30 minutes and hydrolytically condensed to prepare a hydrolytically condensed solution with a solid content of 3% by mass (in terms of SiO2). A coating solution was prepared by mixing 30 parts by mass of the obtained hydrolytically condensed solution and 70 parts by mass of a 3% aqueous solution using "Exceval (trademark) AQ-4104" manufactured by Kuraray Co., Ltd. as a water-soluble resin. The obtained coating solution was applied onto the surface of the alumina-deposited layer AlOx with a wire bar so that the average thickness after drying was 2 μm, and dried at 100 °C for 5 minutes to laminate a protective layer (F), and a vapor-deposited film having a protective layer (F) (F / B / A / C / D = protective layer / AlOx / EVOH1 / MAhPP / BOPP1 = 2 μm / 50 nm / 0.5 μm / 0.5 μm / 20 μm) was produced.

[0122] Next, on one side of the unstretched polypropylene film (CPP3) prepared as the heat-sealing layer (E), a two-component adhesive ("Takelac (trademark) A-520" and "Takonate (trademark) A-50" manufactured by Mitsui Chemicals, Inc.) was applied and dried so that the average thickness after drying was 2 μm to form an adhesive layer (G) (tie), and a multilayer structure (D / C / A / B / F / G / E = BOPP1 / MAhPP / EVOH1 / AlOx / protective layer / tie / CPP3 = 20 μm / 0.5 μm / 0.5 μm / 50 nm / 2 μm / 2 μm / 30 μm) was produced by laminating with the vapor-deposited film having the obtained protective layer (F). The pouch was produced and evaluated in the same manner as in Example 1 except that the obtained multilayer structure was used. The results are shown in Table 1.

[0123] [Comparative Example 2] A multilayer structure and a pouch were produced and evaluated in the same manner as in Example 4, except that an aluminum vapor deposition layer was formed instead of the silica vapor deposition layer. The results are shown in Table 1.

[0124] [Comparative Example 4] A multilayer structure and a pouch were produced and evaluated in the same manner as in Example 12, except that a biaxially stretched PET film (PET) with an average thickness of 12 μm was used instead of the biaxially stretched EVOH1 film. The results are shown in Table 1.

[0125]

Table 1

Claims

1. A package comprising a multilayer structure having a barrier layer (A) mainly composed of an ethylene-vinyl alcohol copolymer (a), an inorganic oxide vapor deposition layer (B) containing at least one selected from the group consisting of aluminum oxide and silicon oxide, and a heat-sealing layer (E) mainly composed of a polyolefin resin (e), wherein the barrier layer (A) and the inorganic oxide vapor deposition layer (B) are directly laminated, having a content containing 1.0% by mass or more of sodium chloride inside the package, wherein the heat-sealing layer (E) is located on the outermost surface on the inner side of the package, and a product having a protective layer (F) directly laminated on the inorganic oxide vapor deposition layer (B) when the inorganic oxide vapor deposition layer (B) contains aluminum oxide as a main component.

2. The product according to claim 1, wherein the barrier layer (A) is stretched at least in one axial direction.

3. The product according to claim 1 or 2, wherein the average thickness of the barrier layer (A) is 0.1 μm or more and 20 μm or less.

4. The product according to claim 1 or 2, wherein the ratio of the average thickness of the barrier layer (A) to the average thickness of the multilayer structure is 5% or less.

5. The product according to claim 1 or 2, wherein the average thickness of the inorganic oxide vapor deposition layer (B) is 10 to 200 nm.

6. The product according to claim 1 or 2, wherein the average thickness of the heat-sealing layer (E) is 5 μm or more and 200 μm or less.

7. The product according to claim 1 or 2, wherein the multilayer structure includes an adhesive layer (C) mainly composed of an adhesive resin (c) and a polyolefin layer (D) mainly composed of a polyolefin resin (d), and the inorganic oxide vapor deposition layer (B), the barrier layer (A), the adhesive layer (C), and the polyolefin layer (D) are laminated in this order.

8. The product according to claim 7, wherein the barrier layer (A), the adhesive layer (C), and the polyolefin layer (D) are stretched at least in one axial direction.

9. The product according to claim 7, wherein the barrier layer (A), the adhesive layer (C), and the polyolefin layer (D) are coextruded films.

10. The product according to claim 7, wherein the resins that are the main components of the polyolefin layer (D) and the heat-sealing layer (E) are the same resin type.

11. The product according to claim 1 or 2, wherein the multilayer structure may have an adhesive layer (G) mainly composed of an adhesive (g), and when the adhesive layer (G) is included, the total average thickness of the adhesive layer (G) is 10 μm or less.

12. The product according to claim 1 or 2, wherein the sodium chloride content of the content is 5% by mass or less.

13. The product according to claim 1 or 2, wherein the content contains moisture.

14. The product according to claim 13, wherein the moisture content of the content is 70% by mass or less.

15. The product according to claim 1 or 2, wherein the content contains lipids.

16. The product according to claim 15, wherein the lipid content of the content is 95% by mass or less.

17. The product according to claim 1 or 2, wherein the pH of the content is 1.0 or more and 6.0 or less.

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