Gas barrier laminate, and packaging material and vacuum heat-insulating material using the same

Abstract

To provide a gas barrier laminate including a polyolefin-based substrate layer and having excellent gas barrier properties even after bending.SOLUTION: A gas barrier laminate according to the present disclosure has a laminated structure comprising, in this order, a polyolefin-based substrate layer, a first polyvinyl alcohol-based resin layer, a vapor deposition layer, and a second polyvinyl alcohol-based resin layer, wherein the vapor deposition layer directly contacts the first polyvinyl alcohol-based resin layer and the second polyvinyl alcohol-based resin layer, and a pressing hardness measured with a nanoindenter in a cross-section of the second polyvinyl alcohol-based resin layer is 0.5 GPa or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a gas barrier laminate, and a packaging material and a vacuum insulation material using the same. [Background technology]

[0002] Gas barrier laminates, which combine a plastic film substrate with a vapor-deposited layer, are widely used as packaging materials for products that require protection from various gases such as water vapor and oxygen. Various improvements to gas barrier laminates have been investigated with the aim of preventing a decrease in gas barrier properties and further improving the barrier properties. For example, Patent Document 1 discloses a gas barrier laminate characterized by having, in this order, a substrate having a polyethylene naphthalate layer, a layer made of a composition containing an acrylic polyol and an isocyanate compound, and an inorganic thin film layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-49266 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, growing environmental awareness stemming from the problem of marine plastic waste has led to calls for further improvements in the efficiency of the sorting and recovery of plastic materials and their recycling. In other words, there is a growing demand for mono-material packaging materials, which have traditionally been made by combining various different materials to achieve high performance.

[0005] The inventors selected polyolefin resin as a material with excellent recyclability, but their investigations revealed that when attempting to realize a monomaterial using polyolefin resin, there was room for improvement in barrier properties after bending.

[0006] The present disclosure provides a gas barrier laminate that includes a polyolefin-based substrate layer and that exhibits excellent gas barrier properties even after folding. The present disclosure also provides a packaging material and a vacuum insulation material that use the gas barrier laminate. [Means for solving the problem]

[0007] In order to solve the above problems, the present disclosure provides the following gas barrier laminate, packaging material, and vacuum insulation material. [1] A polyolefin-based base layer; a first polyvinyl alcohol-based resin layer; a deposition layer; a second polyvinyl alcohol-based resin layer; in this order, the vapor-deposited layer is in direct contact with the first polyvinyl alcohol-based resin layer and the second polyvinyl alcohol-based resin layer, A gas barrier laminate, wherein the second polyvinyl alcohol-based resin layer has an indentation hardness of 0.5 GPa or less in a cross section measured by a nanoindenter. [2] The gas barrier laminate according to [1], wherein the ratio (S2 / S1) of the nanoindenter indentation hardness (S2) of the cross section of the second polyvinyl alcohol-based resin layer to the nanoindenter indentation hardness (S1) of the cross section of the first polyvinyl alcohol-based resin layer is 3 to 10. [3] The gas barrier laminate according to [1] or [2], wherein the first polyvinyl alcohol-based resin layer has a thickness of 0.5 to 2.5 μm. [4] The gas barrier laminate according to any one of [1] to [3], wherein the second polyvinyl alcohol-based resin layer contains Si. [5] The gas barrier laminate according to any one of [1] to [4], wherein the second polyvinyl alcohol-based resin layer contains a silane coupling agent. [6] The gas barrier laminate according to any one of [1] to [5], wherein the vapor-deposited layer contains aluminum or silicon oxide. [7] The gas barrier laminate according to any one of [1] to [6], wherein the polyolefin-based substrate layer and the first polyvinyl alcohol-based resin layer are co-extruded layers. [8] A packaging material comprising the gas barrier laminate according to any one of [1] to [7]. [9] The packaging material according to [8], which is used for packaging that is subjected to vacuum treatment.

[10] The packaging material according to [8], which is used for packaging that is subjected to freezing treatment.

[11] [8] A vacuum insulation material comprising the packaging material described in [8]. [Effects of the Invention]

[0008] According to the present disclosure, there is provided a gas barrier laminate including a polyolefin-based base material layer and exhibiting excellent gas barrier properties even after folding. According to the present disclosure, there are also provided a packaging material and a vacuum insulation material using this gas barrier laminate. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a gas barrier laminate according to one embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view showing a packaging material according to one embodiment. [Figure 3] FIG. 3 is a schematic cross-sectional view showing a packaging material according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described in detail, with reference to the drawings as needed. However, the present disclosure is not limited to the following embodiments.

[0011] The gas barrier laminate according to this embodiment has a laminated structure including, in this order, a polyolefin-based substrate layer, a first polyvinyl alcohol-based resin layer, a vapor-deposited layer, and a second polyvinyl alcohol-based resin layer, the vapor-deposited layer being in direct contact with the first polyvinyl alcohol-based resin layer and the second polyvinyl alcohol-based resin layer, and the indentation hardness of the cross section of the second polyvinyl alcohol-based resin layer measured with a nanoindenter is 0.5 GPa or less.

[0012] The gas barrier laminate exhibits excellent gas barrier properties even after bending. The inventors speculate that the reason for this effect is as follows: The vapor-deposited layer is hard and brittle, and therefore easily damaged by bending. In the gas barrier laminate, the vapor-deposited layer is in direct contact with the first and second polyvinyl alcohol-based resin layers. Furthermore, the indentation hardness of the cross section of the second polyvinyl alcohol-based resin layer measured with a nanoindenter is 0.5 GPa or less. As a result, the polyvinyl alcohol-based resin layer functions as a flexible layer to prevent cracks in the vapor-deposited layer from expanding, and as a gas barrier layer to fill defects in the vapor-deposited layer. Therefore, the gas barrier laminate exhibits excellent gas barrier properties even after bending.

[0013] For example, if another layer is provided between the first and second polyvinyl alcohol-based resin layers and the vapor-deposited layer, gas will escape from the other layer through defects in the vapor-deposited layer.

[0014] The gas barrier laminate uses a polyolefin-based substrate layer as the substrate, and therefore tends to have good slip properties and excellent transportability compared to a case where EVOH is used as the substrate. In addition, the gas barrier laminate uses a polyolefin-based substrate layer as the substrate, and therefore tends to have excellent processability because it is less susceptible to the effects of heat, moisture, etc.

[0015] Fig. 1 is a schematic cross-sectional view showing a gas barrier laminate according to one embodiment. The gas barrier laminate 100 shown in Fig. 1 comprises a polyolefin substrate layer 10, a first polyvinyl alcohol resin layer 11, a vapor-deposited layer 12, and a second polyvinyl alcohol resin layer 13, in this order.

[0016] (Polyolefin-based base layer) The polyolefin-based substrate layer (hereinafter also simply referred to as "substrate layer") is a film that serves as one of the supports, and contains a polyolefin-based resin.

[0017] Examples of polyolefin-based resins include polyethylene (PE), polypropylene (PP), polybutene (PB), and cycloolefin polymers. Other examples of polyolefin-based resins include acid-modified polyolefins obtained by graft-modifying polyolefins with unsaturated carboxylic acids, acid anhydrides of unsaturated carboxylic acids, esters of unsaturated carboxylic acids, and the like. Small amounts of secondary or tertiary components, such as ethylene or butene, may be used as raw material monomers in polypropylene synthesis. Polyethylene is preferred as a polyolefin-based resin because it is highly flexible, making it less likely to tear even when containing heavy liquids, and it conforms easily to the contents regardless of the contents, even when used as a packaging material subjected to vacuum treatment, and its gas barrier properties tend to be less likely to deteriorate. From the perspective of excellent heat resistance, a propylene monopolymer film can be used as the base layer.

[0018] The polyethylene may be, for example, low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), linear low density polyethylene (L·LDPE), ethylene-vinyl acetate copolymer (EVA) or ethylene·α-olefin copolymer.

[0019] The film constituting the base layer may be a stretched film or a non-stretched film. However, from the viewpoints of impact resistance, heat resistance, water resistance, dimensional stability, etc., the film constituting the base layer may be a stretched film. The stretching method is not particularly limited, and any method may be used as long as it can provide a dimensionally stable film, such as stretching by inflation, uniaxial stretching, or biaxial stretching. From the viewpoint of excellent tearability regardless of the tearing direction, a biaxially stretched film is preferred.

[0020] The thickness of the substrate layer is not particularly limited, but from the viewpoint of obtaining excellent impact resistance and excellent gas barrier properties, it can be set to 9 to 100 μm, and may be 15 to 30 μm.

[0021] The film constituting the base layer may be subjected to various pretreatments such as corona treatment, plasma treatment, and flame treatment on the lamination surface within the range that does not impair the barrier performance, or may be provided with a coating layer such as an easy-adhesion layer.

[0022] The film constituting the substrate layer may contain additives such as antistatic agents, ultraviolet absorbers, plasticizers, and slip agents, if necessary.

[0023] The content of the polyolefin resin in the substrate layer may be 70% by mass or more, 80% by mass or more, 90% by mass or more, or 100% by mass based on the total amount of the substrate layer.

[0024] (First polyvinyl alcohol-based resin layer) The polyvinyl alcohol resin may be any resin having a vinyl alcohol unit formed by saponifying a vinyl ester unit, such as polyvinyl alcohol (PVA) or ethylene-vinyl alcohol copolymer (EVOH). From the viewpoints of heat resistance and gas barrier properties, EVOH is preferably used.

[0025] Examples of PVA include resins obtained by homopolymerizing vinyl esters such as vinyl acetate, vinyl formate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl pivalate, and vinyl versatate, followed by saponification.

[0026] The PVA may be a copolymerized or post-modified modified PVA. Copolymerized modified PVA can be obtained, for example, by copolymerizing a vinyl ester with an unsaturated monomer copolymerizable with the vinyl ester, followed by saponification. Post-modified PVA can be obtained by copolymerizing PVA obtained by polymerizing a vinyl ester and then saponifying the copolymer with an unsaturated monomer in the presence of a polymerization catalyst. The amount of modification in the modified PVA can be less than 50 mol % in order to achieve sufficient gas barrier properties, and can be 10 mol % or more in order to obtain the effect of modification.

[0027] Examples of the unsaturated monomer include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, and α-octadecene; hydroxy group-containing α-olefins such as 3-buten-1-ol, 4-pentyn-1-ol, and 5-hexen-1-ol; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, and undecylenic acid; nitriles such as acrylonitrile and methacrylonitrile; amides such as diacetone acrylamide, acrylamide, and methacrylamide; and olefins such as ethylene glycol, propylene glycol, propylene glycol, propylene glycol esters ... Examples of suitable unsaturated monomers include olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid; vinyl compounds such as alkyl vinyl ether, dimethyl allyl vinyl ketone, N-vinyl pyrrolidone, vinyl chloride, vinyl ethylene carbonate, 2,2-dialkyl-4-vinyl-1,3-dioxane, glycerin monoallyl ether, and 3,4-diacetoxy-1-butene; vinylidene chloride, 1,4-diacetoxy-2-butene, vinylene carbonate, polyoxypropylene, and polyoxypropylene vinylamine. From the viewpoint of gas barrier properties, the unsaturated monomer may be an olefin, and in particular, ethylene.

[0028] Examples of the polymerization catalyst include radical polymerization catalysts such as azobisisobutyronitrile, benzoyl peroxide, lauryl peroxide, etc. The polymerization method is not particularly limited, and bulk polymerization, emulsion polymerization, solvent polymerization, etc. can be used.

[0029] The degree of polymerization of PVA is preferably 300 to 3000. When the degree of polymerization is 300 or more, the barrier property tends to be even better, and when it is 3000 or less, the coating suitability tends to be excellent. The saponification degree of PVA is preferably 80 mol% or more, more preferably 90 mol% or more, and even more preferably 98 mol% or more. The saponification degree of PVA may be 100 mol% or less, or may be 99.9 mol% or less. The polymerization degree and saponification degree of PVA can be measured in accordance with the method described in JIS K 6726 (1994).

[0030] EVOH is generally obtained by saponifying a copolymer of ethylene and an acid vinyl ester such as vinyl acetate, vinyl formate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl pivalate, or vinyl versatate.

[0031] The ethylene unit content of EVOH is 10 mol% or more, more preferably 15 mol% or more, even more preferably 20 mol% or more, and particularly preferably more than 35 mol%. The ethylene unit content of EVOH is preferably 65 mol% or less, more preferably 55 mol% or less, and even more preferably less than 50 mol%. When the ethylene unit content is 10 mol% or more, the gas barrier properties or dimensional stability can be maintained well under high humidity. On the other hand, when the ethylene unit content is 65 mol% or less, the gas barrier properties can be improved. The ethylene unit content of EVOH can be determined by NMR.

[0032] Saponification can be carried out using an alkali or an acid, but alkali can be used from the viewpoint of saponification rate. Examples of alkali include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and alkali metal alkoxides such as sodium ethylate, potassium ethylate, and lithium methylate.

[0033] The thickness of the first polyvinyl alcohol-based resin layer is not particularly limited, but from the viewpoint of barrier properties and processability, it can be 0.05 to 5 μm, or alternatively 0.5 to 2.5 μm, or alternatively 0.3 to 1.5 μm.

[0034] The mass per unit area of ​​the first polyvinyl alcohol-based resin layer is 0.1 to 10 g / m 2 This mass can be set to 0.1 g / m 2 When the mass is 10 g / m or more, the surface of the first polyvinyl alcohol-based resin layer can be formed to be sufficiently smooth even if the surface of the base layer is insufficiently smooth, and a vapor deposition layer with excellent gas barrier properties can be formed on the surface. 2 The following is advantageous in terms of realizing a mono-material packaging material and reducing material costs.

[0035] The indentation hardness of the cross section of the first polyvinyl alcohol-based resin layer as measured by a nanoindenter may be 0.05 to 0.1 GPa. The indentation hardness is measured by the method described in the examples below.

[0036] (deposited layer) The vapor-deposited layer is a layer (gas barrier layer) that exhibits gas barrier properties against water vapor and oxygen. The vapor-deposited layer may contain at least one of a metal and an inorganic oxide. The vapor-deposited layer may have a single-layer structure or a laminate structure. The vapor-deposited layer contains at least one of a metal vapor-deposited layer and an inorganic oxide layer. When the vapor-deposited layer includes a metal vapor-deposited layer, examples of the metal contained in the metal vapor-deposited layer include aluminum and stainless steel. When the vapor-deposited layer includes an inorganic oxide layer, examples of the inorganic oxide contained in the inorganic oxide layer include aluminum oxide, silicon oxide, magnesium oxide, and tin oxide. From the viewpoints of transparency and barrier properties, the inorganic oxide may be selected from the group consisting of aluminum oxide, silicon oxide, and magnesium oxide. Furthermore, from the viewpoint of excellent tensile stretchability during processing, it is preferable to use a layer using silicon oxide as the inorganic oxide layer. By using an inorganic oxide layer, high barrier properties can be obtained with a very thin layer that does not affect the recyclability of the gas barrier laminate.

[0037] The thickness of the vapor-deposited layer can be 5 to 80 nm. When the thickness is 5 nm or more, sufficient gas barrier properties are easily obtained. Furthermore, when the thickness is 80 nm or less, cracks caused by deformation due to internal stress in the thin film are suppressed, and deterioration of gas barrier properties is easily suppressed. From the above viewpoint, the thickness of the vapor-deposited layer may be 10 to 50 nm, or may be 20 to 40 nm.

[0038] (Second polyvinyl alcohol-based resin layer) For the polyvinyl alcohol-based resin constituting the second polyvinyl alcohol-based resin layer, the contents explained in the section on the first polyvinyl alcohol-based resin layer can be referred to.

[0039] The indentation hardness of the cross section of the second polyvinyl alcohol-based resin layer measured with a nanoindenter is 0.5 GPa or less, and is preferably less than 0.5 GPa, more preferably 0.4 GPa or less, and even more preferably 0.3 GPa or less, since this provides even better gas barrier properties after bending. The indentation hardness of the second polyvinyl alcohol-based resin layer may be 0.05 GPa or more. The indentation hardness is measured by the method described in the Examples below.

[0040] The ratio (S2 / S1) of the nanoindenter indentation hardness (S2) of the cross section of the second polyvinyl alcohol-based resin layer to the nanoindenter indentation hardness (S1) of the cross section of the first polyvinyl alcohol-based resin layer is preferably 3 to 10, as this provides even better gas barrier properties after bending.

[0041] The second polyvinyl alcohol-based resin layer may contain Si. Specifically, the second polyvinyl alcohol-based resin layer may be a cured product of raw materials containing a polyvinyl alcohol-based resin and a silane compound. Examples of the silane compound include tetraalkoxysilanes such as tetramethoxysilane and tetraethoxysilane, and silazanes such as hexamethyldisilazane. Examples of the silane compound include compounds commonly used as silane coupling agents and polysiloxane compounds having a siloxane bond. Examples of the silane coupling agent include epoxysilanes (glycidoxypropyltrimethoxysilane, etc.), (meth)acrylicsilanes (acryloxypropyltrimethoxysilane, etc.), aminosilanes, ureidosilanes, isocyanatesilanes, isocyanuratesilanes (tris(3-trialkoxysilylpropyl)isocyanurate, etc.), and mercaptosilanes.

[0042] When forming the second polyvinyl alcohol-based resin layer, the amount of the silane compound in the raw materials can be set to 0.1 to 10 parts by mass, or alternatively 0.5 to 8 parts by mass, or alternatively 1 to 5 parts by mass, per part by mass of the polyvinyl alcohol-based resin, in order to adjust the indentation hardness of the cross section of the second polyvinyl alcohol-based resin layer using a nanoindenter and ensure that the resulting gas barrier laminate has excellent gas barrier properties after bending.

[0043] The thickness of the second polyvinyl alcohol-based resin layer is not particularly limited, but from the viewpoint of barrier properties and processability, it can be 0.05 to 2 μm, may be 0.1 to 0.6 μm, or may be 0.2 to 0.5 μm.

[0044] <Method of manufacturing gas barrier laminate> The gas barrier laminate can be produced, for example, by a production method including the steps of forming a first polyvinyl alcohol-based resin layer on a base layer, forming a vapor-deposited layer on the first polyvinyl alcohol-based resin layer, and forming a second polyvinyl alcohol-based resin layer on the vapor-deposited layer.

[0045] (Step of forming first polyvinyl alcohol-based resin layer) In this step, a coating liquid containing a polyvinyl alcohol-based resin and a liquid medium can be used. The coating liquid can be obtained, for example, by dissolving a powder of a polyvinyl alcohol-based resin obtained by synthesis in a liquid medium. Examples of liquid media include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine. These may be used alone or in combination. From the perspective of reducing environmental impact, water can be used as the liquid medium. In this case, the coating liquid can be obtained by dissolving a powder of a polyvinyl alcohol-based resin in water at a high temperature (e.g., 80°C).

[0046] The content of the polyvinyl alcohol resin (solid content) in the coating liquid can be set to 3 to 20% by mass in order to maintain good coating properties.

[0047] The coating liquid may contain additives such as isocyanate and polyethyleneimine to improve adhesion, as well as preservatives, plasticizers, alcohols, surfactants, and the like.

[0048] The coating liquid can be applied to the substrate layer by any appropriate method. The coating liquid can be applied by a wet film-forming method using, for example, a gravure coater, a dip coater, a reverse coater, a wire bar coater, or a die coater. The application temperature and drying temperature of the coating liquid are not particularly limited and can be, for example, 50°C or higher.

[0049] The first polyvinyl alcohol-based resin layer may be formed on the substrate layer by extrusion. In the case of extrusion, multi-layer extrusion using a T-die can be adopted. Examples of adhesives that can be used during extrusion include maleic anhydride-modified polypropylene resin.

[0050] The adhesive component may be applied to a substrate layer and then dried to form an adhesive layer on the substrate layer in advance.

[0051] The thickness of the adhesive layer can be set to 0.1 to 50 μm, and may be 0.5 to 20 μm, from the viewpoints of adhesiveness, followability, processability, and the like.

[0052] The base layer and the first polyvinyl alcohol-based resin layer may be coextruded layers formed by coextrusion. When these layers are coextruded layers, the laminate tends to be tightly adhered and to easily maintain gas barrier properties.

[0053] (Step of forming a vapor deposition layer) The deposition layer can be formed by, for example, vacuum film formation. In vacuum film formation, physical vapor deposition or chemical vapor deposition can be used. Examples of physical vapor deposition include, but are not limited to, vacuum deposition, sputtering, and ion plating. Examples of chemical vapor deposition include, but are not limited to, thermal CVD, plasma CVD, and photo CVD.

[0054] In the vacuum film formation, resistance heating vacuum deposition, EB (Electron Beam) heating vacuum deposition, induction heating vacuum deposition, sputtering, reactive sputtering, dual magnetron sputtering, plasma enhanced chemical vapor deposition (PECVD), and the like are particularly preferably used. However, in terms of productivity, vacuum deposition is currently the most superior. As a heating means for vacuum deposition, it is preferable to use any of the electron beam heating method, resistance heating method, and induction heating method.

[0055] (Step of forming second polyvinyl alcohol-based resin layer) In this step, a coating liquid can be used in the same manner as in the step of forming the first polyvinyl alcohol-based resin layer. Regarding the coating liquid, the details described in the section on the step of forming the first polyvinyl alcohol-based resin layer can be referred to.

[0056] The coating liquid for forming the second polyvinyl alcohol-based resin layer may contain a silane compound, and the content of the silane compound in the coating liquid may be adjusted so that a desired amount of the silane compound is contained relative to the amount of the polyvinyl alcohol-based resin.

[0057] When the coating solution contains a silane compound, the coating solution may further contain an acid catalyst, an alkali catalyst, a photopolymerization initiator, and the like.

[0058] <Packaging material> The packaging material comprises the gas barrier laminate and a sealant layer provided on the surface of the gas barrier laminate. Examples of the sealant layer include a layer containing a polyolefin resin or a polyester resin. Examples of polyolefin resins include polyethylene (PE), polypropylene (PP), polybutene (PB), and cycloolefin polymer. Examples of polyolefin resins include acid-modified polyolefins obtained by graft-modifying polyolefins with unsaturated carboxylic acids, acid anhydrides of unsaturated carboxylic acids, esters of unsaturated carboxylic acids, and the like. Small amounts of secondary or tertiary components, such as ethylene or butene, may be used as raw material monomers in polypropylene synthesis. Polyolefin resins are preferably polyethylene because of their high flexibility, which makes them less likely to tear even when containing heavy liquids, and because they conform easily to the contents regardless of the contents, even when used as packaging materials that undergo vacuum treatment, and therefore tend to be less susceptible to deterioration of gas barrier properties. The polyethylene is, for example, low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), linear low-density polyethylene (L·LDPE), ethylene-vinyl acetate copolymer (EVA), or ethylene-α-olefin copolymer. Fig. 2 is a schematic cross-sectional view showing a packaging material according to one embodiment.

[0059] The packaging material 200 shown in FIG. 2 comprises a gas barrier laminate 100 and a sealant layer 14 provided on the surface of the gas barrier laminate 100 opposite the substrate layer (on the surface of the second polyvinyl alcohol-based resin layer). For example, if both the substrate layer 10 and the sealant layer 14 are made of polyolefin-based resin, the content of the polyolefin-based resin can be 90% by mass or more (preferably 95% by mass or more) based on the total mass of the packaging material 200. Such a packaging material 200 can be a mono-material. The packaging material 200 is suitable for use in packages that undergo vacuum treatment. During vacuum treatment, the packaging material is bent due to the contents. The packaging material 200 comprises a gas barrier laminate that exhibits excellent gas barrier properties even after folding, and therefore exhibits excellent gas barrier properties even after vacuum treatment. The packaging material 200 is also suitable for use in packages that undergo freezing treatment. Here, the packaging comprises a packaging bag formed from the packaging material 200 and contents to be contained in the packaging bag.

[0060] The contents include, for example, food, liquid, medicine, electronic components, and the insulating core material described below.

[0061] When both the base material layer 10 and the sealant layer 14 are made of polypropylene, the polypropylene content can be 90% by mass or more (preferably 95% by mass or more) based on the total mass of the packaging material 200. When both the base material layer 10 and the sealant layer 14 are made of polyethylene, the polyethylene content can be 90% by mass or more (preferably 95% by mass or more) based on the total mass of the packaging material 200. It is preferable that both the base material layer 10 and the sealant layer 14 contain polyethylene because they are highly flexible and therefore less likely to tear even when containing heavy liquids, and they easily conform to the contents regardless of the contents even when used as packaging materials that are subjected to vacuum treatment, and therefore their gas barrier properties tend to be less likely to deteriorate.

[0062] The content of polyolefin resin in the packaging material 200 is preferably 90 mass % based on the total amount of the packaging material 200 .

[0063] The packaging material of the present disclosure is not limited to the above embodiment. For example, the packaging material 200 may further include a resin layer between the sealant layer and the gas barrier laminate. Examples of materials that can form such a resin layer include nylon, polyethylene terephthalate, and polyolefin.

[0064] The packaging material of the present disclosure may further include a gas barrier laminate. The packaging material 300 shown in Fig. 3 includes a gas barrier laminate 100a, a resin layer 15, a gas barrier laminate 100b, and a sealant layer 14. The packaging material 300 is suitable for use as a vacuum insulation material. The vacuum insulation material includes a packaging bag formed of the packaging material 300 and an insulating core material housed in the packaging bag. Examples of insulating core materials include glass fiber and rigid urethane.

[0065] The pressure inside the packaging material 300 in the vacuum insulation material is 10 5 Pa or less, 10 2 Pa or less, 10 -1 Pa or less, 10 -5 Pa or less or 10 -8 Pa or less, -8 Pa or above, 10 -5 Pa or above, 10 -1 Pa or above or 10 2 It may be Pa or more.

[0066] Vacuum insulation materials can be used, for example, as components for covering the outer surfaces of refrigerated and heated appliances to maintain thermal insulation, components for covering the outer surfaces of refrigerated and heated containers to maintain thermal insulation, and exterior wall materials used in construction. Examples of refrigerated and heated appliances include vending machines, refrigerators, freezers, thermoses, and rice cookers. Examples of refrigerated and heated appliances include cooler boxes and water bottles. Examples of buildings in which exterior wall materials are used include homes and cold storage warehouses.

[0067] In the packaging material 300, the gas barrier laminate 100b is arranged so that the second polyvinyl alcohol-based resin layer 13 is on the resin layer side 15, but it may also be positioned so that the base material layer 10 is on the resin layer 15 side. [Example]

[0068] The present disclosure will be specifically described below using examples, but the present disclosure is not limited to these examples.

[0069] The following materials were prepared: (film) CPP film: Toray Industries, product name "Torayfan ZK207", thickness 60 μm LLDPE film 1: Mitsui Chemicals Tocello, product name "TUX-MCS", thickness 60 μm LLDPE film 2: Mitsui Chemicals Tocello Co., Ltd., product name "FCS", thickness 40 μm ONY film: Manufactured by Unitika Ltd., product name "Emblem ONM", thickness 15 μm (glue) Mitsui Chemicals SKC Polyurethanes Co., Ltd., product name "A525 / A52", two-component (Coating liquid A) Polyvinyl alcohol (trade name: Kuraray Poval 60-98, manufactured by Kuraray Co., Ltd., hereinafter also referred to as "PVA") was prepared into an aqueous solution with a solid content of 5%. (Coating liquid B) Tetraethoxysilane (trade name: KBE04, solid content: 100%, manufactured by Shin-Etsu Chemical Co., Ltd., hereinafter also referred to as "TEOS"), methanol (Kanto Chemical), and 0.1N hydrochloric acid (Kanto Chemical) were mixed in a weight ratio of 17 / 10 / 73 to prepare a hydrolysis solution with a solid content of 5% (weight ratio calculated as SiO2). (Coating liquid C) A hydrolysis solution of 1,3,5-tris(3-methoxysilylpropyl) isocyanurate (silane coupling agent) with a solid content of 5% (weight ratio calculated as RSi(OH)3) was prepared in a water / IPA=1 / 1 solution.

[0070] [First Consideration] <Preparation of gas barrier laminate> Example 1 An OPP film (polyolefin-based base layer) was formed using polypropylene monomer resin, and at the same time, an EVOH layer (first polyvinyl alcohol-based resin layer) was formed on the surface of the OPP film by coextrusion. The mass per unit area of ​​the EVOH layer was 0.97 g / m. 2 It was.

[0071] Using an electron beam heating vacuum deposition device, silicon oxide was deposited on the surface of the first polyvinyl alcohol resin layer to form a SiO x A vapor deposition film (vapor deposition layer, thickness: 50 nm) was formed.

[0072] A mixture was obtained by mixing coating liquids A, B, and C. The mixing ratio of coating liquids A, B, and C was adjusted so that the solid mass ratio of PVA / SiO2 / silane coupling agent (SC agent) was as shown in Table 1. The mixture was applied to the surface of the vapor deposition layer opposite the first polyvinyl alcohol-based resin layer to form a coating film, and the coating film was dried to form a second polyvinyl alcohol-based resin layer (thickness: 300 nm). This resulted in a gas barrier laminate.

[0073] Example 2 SiO x A gas barrier laminate was obtained in the same manner as in Example 1, except that instead of a vapor deposition film, an electron beam heating vacuum deposition apparatus was used to vapor deposit Al on the surface of the first polyvinyl alcohol-based resin layer to form an Al vapor deposition film (thickness: 50 nm).

[0074] Example 3 A polypropylene film (manufactured by Mitsui Chemicals Tohcello, product name "ME-1", thickness: 20 μm) was prepared as a substrate layer. An EVOH solution (manufactured by Mitsubishi Chemical, product name: 16DX) was dissolved in a mixed solution of water and IPA to prepare a solution with a solid content of 5 mass %. The resulting solution was applied to the corona-treated surface of the polypropylene film to form a coating film, and the coating film was dried to form a first polyvinyl alcohol-based resin layer (thickness: 0.8 μm). In the same manner as in Example 1, a vapor deposition layer was formed on the surface of the first polyvinyl alcohol-based resin layer, and a second polyvinyl alcohol-based resin layer was formed on the vapor deposition layer, thereby obtaining a gas barrier laminate.

[0075] Example 4 A gas barrier laminate was obtained in the same manner as in Example 3, except that the mixing ratio of coating solutions A, B, and C (PVA / SiO 2 / SC agent) was adjusted to the solid content mass ratio shown in Table 1.

[0076] Example 5 A gas barrier laminate was obtained in the same manner as in Example 1, except that a biaxially oriented HDPE (BOPE: Biaxially Oriented Polyethylene) film was used as the polyolefin-based base layer instead of the OPP film.

[0077] Example 6 A gas barrier laminate was obtained in the same manner as in Example 2, except that a biaxially oriented HDPE film (thickness: 24.2 nm) was used as the polyolefin-based base layer instead of the OPP film, and the thickness of the AL vapor-deposited film was set to 75 nm.

[0078] Example 7 A gas barrier laminate was obtained in the same manner as in Example 5, except that the mixing ratio of coating solutions A, B, and C (PVA / SiO 2 / SC agent) was adjusted to the solid content mass ratio shown in Table 2.

[0079] Example 8 A gas barrier laminate was obtained in the same manner as in Example 6, except that the mixing ratio of coating solutions A, B, and C (PVA / SiO 2 / SC agent) was adjusted to the solid content mass ratio shown in Table 2.

[0080] (Comparative Example 1) A gas barrier laminate was obtained in the same manner as in Example 1, except that the mixing ratios of coating solutions A, B, and C were set to the solid content mass ratios shown in Table 1.

[0081] (Comparative Example 2) A biaxially stretched EVOH film (manufactured by Kuraray Co., Ltd., trade name "VM-XL") on which AL was vapor-deposited was used as the gas barrier laminate.

[0082] (Comparative Example 3) A gas barrier laminate was obtained in the same manner as in Example 1, except that the second polyvinyl alcohol-based resin layer was not formed.

[0083] Comparative Example 4 A polypropylene film (thickness: 20 μm) was prepared as a substrate layer. An anchor coat layer was formed on the surface of the substrate layer. Using an electron beam heating vacuum deposition device, silicon oxide was deposited on the surface of the anchor coat layer to form SiO x A vapor deposition film (vapor deposition layer, thickness: 50 nm) was formed. A mixture was obtained by mixing coating liquids A, B, and C in the same manner as in Example 1. The mixture was applied to the surface of the vapor deposition layer opposite the substrate layer to form a coating film, and the coating film was dried to form a second polyvinyl alcohol-based resin layer (thickness: 300 nm). This produced a gas barrier laminate.

[0084] (Comparative Example 5) A gas barrier laminate was obtained in the same manner as in Example 5, except that the mixing ratio of coating solutions A, B, and C (PVA / SiO 2 / SC agent) was adjusted to the solid content mass ratio shown in Table 2.

[0085] (Comparative Example 6) A gas barrier laminate was obtained in the same manner as in Example 5, except that the second polyvinyl alcohol-based resin layer was not formed.

[0086] (Comparative Example 7) A biaxially stretched HDPE film (thickness: 25 nm) on which AL (thickness: 75 nm) was vapor-deposited was used as the gas barrier laminate.

[0087] <Measurement of indentation hardness> The indentation hardness of the first and second polyvinyl alcohol-based resin layers of the gas barrier laminates obtained in each Example and Comparative Example was measured. The indentation hardness was measured by nanoindentation. Nanoindentation is a measurement method in which a quasi-static indentation test is performed on a target object to obtain the mechanical properties of the sample.

[0088] Measurement samples (cross-section samples) were prepared as follows. After corona treatment on both sides of the gas barrier laminate, it was embedded in visible light-curable resin D-800. The gas barrier laminate was then cut perpendicular to the lamination direction using a diamond knife Microstar LH on a Leica EM UC7 ultramicrotome. The resulting cross section was then finished at a cutting thickness of 100 nm and a cutting speed of 1 mm / s to prepare a measurement sample.

[0089] For the measurement, a Hysitron TI-Premier (trade name) manufactured by Bruker Japan Co., Ltd. was used as the measuring device, and a Berkovich type diamond indenter manufactured by Bruker Japan Co., Ltd. was used as the indenter. The measurement conditions were as follows.

[0090] Temperature: normal temperature (25℃). Mode: Load control mode. Indentation and unloading: Indentation was performed up to a load of 15 μN at an indentation speed of 1.5 μN / sec, and the maximum load was maintained for 5 seconds, after which the load was unloaded at a speed of 1.5 μN / sec. Measurement locations: Using the shape measurement function of the measuring device, which scans the sample surface with an indenter, a shape image of the cross section of the second polyvinyl alcohol-based resin layer is obtained, and 20 points are specified on the cross section of the second polyvinyl alcohol-based resin layer at intervals of 1 μm or more from the shape image.

[0091] To calculate the indentation hardness, we used fused silica as a standard sample to calibrate the relationship between the contact depth and the projected contact area between the indenter and the sample. We then analyzed the unloading curve in the 60-95% range of the maximum load at unloading using the Oliver-Pharr method to calculate the indentation hardness.

[0092] <Evaluation of the lubricity of gas barrier laminate> The coefficient of dynamic friction between the main surface on the substrate layer side and the main surface on the opposite side of the gas barrier laminate of each Example and Comparative Example was measured. The measurement was performed in accordance with JIS K7125, with a test width of 80 × 200 mm and a contact area of ​​the sliding piece of 40 cm. 2 The test was carried out at a sliding speed of 100 mm / min. The measured values ​​(unit: μD) were evaluated according to the following criteria. The results are shown in Tables 1 and 2.

[0093] (standard) A: Measurement value is 1.0 μD or less B: The measured value is more than 1.0 μD or the laminate does not slide and zippering occurs, making it impossible to measure

[0094] <Transportability> A first raw web was prepared by winding up the gas barrier laminate (width: 500 mm) of each Example and Comparative Example. The gas barrier laminate was fed from the raw web in a roll-to-roll manner and wound up as a second raw web. The feeding speed was 50 m / min. If wrinkles occurred on the second raw web, it was rated as "B", and if no wrinkles occurred, it was rated as "A". The results are shown in Tables 1 and 2.

[0095] <Polyolefin resin mass ratio> (Examples 1 to 4, Comparative Examples 1 to 4) The gas barrier laminates of each Example and Comparative Example were dry-laminated with a CPP film (sealant layer, manufactured by Mitsui Chemicals Tohcello, Inc., product name "TUX-MCS", thickness: 60μ) using a 3μ thick two-component curing adhesive (manufactured by Mitsui Chemicals, product names "A525" and "A50") to obtain a laminate film. The CPP film was attached to the surface of the gas barrier laminate opposite the base layer.

[0096] The mass ratio of the polyolefin resin (polypropylene) in the laminate film was calculated from the masses of the gas barrier laminate, CPP film (thickness: 60 μm), and adhesive (thickness: 3 μm). The results are shown in Table 1.

[0097] (Examples 5 to 8, Comparative Examples 5 to 7) Except for using LLDPE film 1 instead of CPP film as the sealant layer, the mass ratio of polyolefin resin (polyethylene) in the laminate film was determined in the same manner as in Examples 1 to 4 and Comparative Examples 1 to 4. The results are shown in Table 2.

[0098] <Oxygen permeability measurement (initial)> (Examples 1 to 4, Comparative Examples 1 to 4) The gas barrier laminate of each Example and Comparative Example was dry-laminated to a CPP film (sealant layer) using an adhesive to obtain a laminate film. The gas barrier laminate was attached so that the surface opposite the base layer of the gas barrier laminate faced the CPP film. The oxygen permeability of the laminate film was measured. Measurements were carried out using an oxygen permeability measuring device (OXTRAN 2 / 20, manufactured by Modern Control) at a temperature of 30°C and a relative humidity of 70%. The measurement method complied with JIS K-7126, Method B (constant pressure method), and ASTM D3985-81. The results are shown in Table 1. Measurements are in units of [cc / m 2 ·day·atm].

[0099] (Examples 5 to 8, Comparative Examples 5 to 7) Except for using LLDPE film 1 instead of the CPP film as the sealant layer, the oxygen permeability was measured in the same manner as in Examples 1 to 4 and Comparative Examples 1 to 4. The results are shown in Table 2.

[0100] <Water vapor permeability measurement (initial)> Laminate films were obtained using the gas barrier laminates of each Example and Comparative Example in the same manner as in the oxygen permeability measurement (initial stage). The water vapor permeability of the laminate films was measured. The measurement was carried out using an oxygen permeability measuring device (PERMATRAN 3 / 31, manufactured by Modern Control) under conditions of a temperature of 40°C and a relative humidity of 90%. The measurement method complied with JIS K-7126, Method B (constant pressure method), and ASTM D3985-81. The results are shown in Tables 1 and 2. The measured values ​​are in units of [g / m 2 ·day].

[0101] <Lamination strength> Laminate films were obtained using the gas barrier laminates of each Example and Comparative Example in the same manner as in the oxygen permeability measurement (initial). The laminate strength of the laminate films was measured. The measurement was performed in accordance with JIS K6854, with a test width of 15 mm, a peel rate of 300 mm / min, and a peel angle of 180°. The results are shown in Tables 1 and 2. The measured values ​​were expressed in units of [N / 15 mm].

[0102] <Bending test> A laminate film was obtained using the gas barrier laminate of each Example and Comparative Example in the same manner as in the oxygen permeability measurement (initial stage). A 210 mm x 297 mm test piece was cut out from the laminate film. Both ends of the test piece were attached together and rolled into a cylindrical shape. Both ends of the cylindrical test piece were held with a fixed head and a drive head. The following steps 1 to 4 constitute one cycle, and 100 cycles were performed at 25°C. The cycle speed was 40 cycles / min. The oxygen permeability after the flex test was measured in the same manner as in the oxygen permeability measurement (initial stage). The water vapor permeability after the flex test was measured in the same manner as in the water vapor permeability measurement (initial stage).

[0103] Step 1: The test specimen is twisted 440 degrees while the distance between the fixed and driven heads is narrowed from 7 inches to 3.5 inches. Step 2: While twisting the test piece, narrow the head spacing to 1 inch. Step 3: Increase the head spacing to 3.5 inches. Step 4: Untwist and widen the head spacing to 7 inches.

[0104] [Table 1]

[0105] [Table 2]

[0106] [Second Consideration] <Laminate film manufacturing> Example 1A A gas barrier laminate was obtained in the same manner as in Example 1 of the first study. The gas barrier laminate and a CPP film (sealant layer) were dry-laminated with an adhesive to obtain a laminate film. The gas barrier laminate was attached so that the surface of the second polyvinyl alcohol-based resin layer side of the gas barrier laminate faced the CPP film.

[0107] Example 1B A laminate film was obtained in the same manner as in Example 1A, except that LLDPE film 1 was used instead of the CPP film.

[0108] Example 1C A gas barrier laminate was obtained in the same manner as in Example 1 of the first study. The gas barrier laminate and an ONY film were dry-laminated using an adhesive to obtain a laminate. The gas barrier laminate was attached so that the surface of the second polyvinyl alcohol-based resin layer side and the ONY film faced each other. Next, the surface of the laminate on the ONY film side and an LLDPE film 1 were dry-laminated using an adhesive to obtain a laminate film.

[0109] (Comparative example 3A) A laminate film was obtained in the same manner as in Example 1A, except that the gas barrier laminate of Example 1 was replaced with the gas barrier laminate of Comparative Example 3.

[0110] <Gas barrier properties after vacuum processing> The laminate film of each example and comparative example was cut into a size of 315 mm length x 230 mm width. This was folded in half and heat-sealed on three sides to produce a pouch with an opening. Marbles with a diameter of 1 cm to 2 cm were placed in this pouch. Next, a package was obtained that had been vacuum-treated using a small chamber vacuum packaging machine. The package was opened after one hour. The oxygen permeability and water vapor permeability of the opened packaging bag were measured in the same manner as in the oxygen permeability measurement (initial) and water vapor permeability measurement (initial). The results are shown in Table 3.

[0111] <Gas barrier properties after vacuum treatment and boiling treatment> The laminate film of each example and comparative example was cut into a size of 315 mm length x 230 mm width. This was folded in half and three sides were heat-sealed to produce a pouch with an opening. Marbles with a diameter of 1 cm to 2 cm were placed in this pouch. Next, a package was vacuum-treated using a small chamber vacuum packaging machine to obtain a package. The package was opened after 10 minutes, water was added again, and the opening was heat-sealed to obtain a package. The package was boiled at 90°C for 3 minutes. The oxygen permeability and water vapor permeability of the packaging bag after boiling were measured in the same manner as in the oxygen permeability measurement (initial) and water vapor permeability measurement (initial). The results are shown in Table 3.

[0112] <Whether or not food discolors after vacuum processing and freezing processing> The laminated film of each example and comparative example was cut into a size of 315 mm length x 230 mm width. This was folded in half and heat-sealed on three sides to produce a pouch with an opening. Red fish meat (yellowtail) was filled into this pouch and vacuum-treated to obtain a package. The package was stored at -25°C for one month. Photographs of the package before and after storage were visually compared. Packages that showed no change in the color of the red fish meat were rated "A," and packages that had turned brown due to freezer burn were rated "B." The results are shown in Table 3.

[0113] [Table 3]

[0114] [Third Consideration] Example 1D Two gas barrier laminates were obtained in the same manner as in Example 1 of the first study. The second polyvinyl alcohol-based resin layer of the first gas barrier laminate of Example 1 was dry-laminated with an ONY film using an adhesive to obtain a first laminate. Next, the surface of the first laminate facing the ONY film was dry-laminated with an adhesive to the surface of the second polyvinyl alcohol-based resin layer of the second gas barrier laminate of Example 1 to obtain a second laminate. The surface of one of the base layer sides of the second laminate was dry-laminated with an LLDPE film 2 using an adhesive to obtain a laminate film.

[0115] (Comparative example 3B) A laminate film was obtained in the same manner as in Example 1D, except that the gas barrier laminate of Example 1 was replaced with the gas barrier laminate of Comparative Example 3.

[0116] <Evaluation of vacuum insulation materials> Vacuum insulation materials were manufactured from the laminate films of Example 1D and Comparative Example 3B. Specifically, two sheets of each laminate film (size: 300 mm × 300 mm) were prepared. The laminate films were placed facing each other and heat-sealed on three sides to obtain a packaging bag for containing an insulating core material with only one side open. Glass fiber (290 × 290 mm) that had been dried (temperature: 120°C, time: 1 hour) was prepared as the insulating core material. The glass fiber was placed in the packaging bag. The internal space of the packaging bag was evacuated to a pressure of 1.0 Pa, and the opening of the bag was then heat-sealed to seal it. This resulted in a vacuum insulation material (thickness: 5 mm, length: 300 mm, width: 300 mm).

[0117] The vacuum insulation material was stored at 60°C for two weeks. The thermal conductivity of the vacuum insulation material was measured before and after storage. Thermal conductivity was measured by a heat flow meter method using a thermal conductivity measuring device (manufactured by Eiko Seiki, product name "HC-074") in accordance with JIS-A-1412-3. The thermal conductivity before storage of Example 1D and Comparative Example 3B was both 0.005 [W / M·K]. The thermal conductivity after storage of Example 1D remained unchanged at 0.005 [W / M·K]. On the other hand, the thermal conductivity after storage of Comparative Example 3B was greater than 0.005 [W / M·K]. [Explanation of symbols]

[0118] 10...base material layer, 11...first polyvinyl alcohol-based resin layer, 12...vapor-deposited layer, 13...second polyvinyl alcohol-based resin layer, 100...gas barrier laminate, 200, 300...packaging material.

Claims

1. a polyolefin-based substrate layer; a first polyvinyl alcohol-based resin layer; a deposition layer; a second polyvinyl alcohol-based resin layer; in this order, the vapor-deposited layer is in direct contact with the first polyvinyl alcohol-based resin layer and the second polyvinyl alcohol-based resin layer, a gas barrier laminate, wherein the second polyvinyl alcohol-based resin layer has an indentation hardness of 0.5 GPa or less in a cross section measured with a nanoindenter;

2. 2. The gas barrier laminate according to claim 1, wherein a ratio (S2 / S1) of a nanoindenter indentation hardness (S2) of a cross section of the second polyvinyl alcohol-based resin layer to a nanoindenter indentation hardness (S1) of a cross section of the first polyvinyl alcohol-based resin layer is 3 to 10.

3. 2. The gas barrier laminate according to claim 1, wherein the first polyvinyl alcohol-based resin layer has a thickness of 0.5 to 2.5 μm.

4. The gas barrier laminate according to claim 1 , wherein the second polyvinyl alcohol-based resin layer contains Si.

5. The gas barrier laminate according to claim 1 , wherein the second polyvinyl alcohol-based resin layer contains a silane coupling agent.

6. The gas barrier laminate according to claim 1 , wherein the vapor-deposited layer comprises aluminum or silicon oxide.

7. The gas barrier laminate according to claim 1 , wherein the polyolefin-based substrate layer and the first polyvinyl alcohol-based resin layer are co-extruded layers.

8. A packaging material comprising the gas barrier laminate according to any one of claims 1 to 7.

9. The packaging material according to claim 8, which is used for packaging that is subjected to vacuum treatment.

10. The packaging material according to claim 8, which is used for packaging that is subjected to freezing treatment.

11. A vacuum insulation material comprising the packaging material according to claim 8.

Images