Gas barrier laminate and packaging bag

Abstract

The gas barrier laminate according to an aspect of the present disclosure has a structure in which a polyolefin-containing substrate layer, an undercoat layer, an inorganic oxide layer, a gas barrier adhesive layer, and a polyolefin-containing resin layer are laminated in the stated order.

Description

[Technical Field]

[0001] The present disclosure relates to a gas barrier laminate and a packaging bag. [Background technology]

[0002] BACKGROUND ART Laminates are known that include a biaxially oriented PET (polyethylene terephthalate) film, which has excellent heat resistance and toughness, as a base film, and a polyolefin film such as polyethylene or polypropylene as a sealant layer (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-178357 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 sorted collection and recycling of plastic materials. In other words, there is a growing demand for mono-materialization of packaging laminates, which have traditionally been made by combining various different materials to achieve high performance.

[0005] To achieve a mono-material laminate, the constituent films must be made of the same material. For example, polyethylene film, a type of polyolefin film, is widely used as a packaging material, and its potential for mono-materialization is anticipated. However, one of the basic physical properties of polyethylene film is its low melting point, which makes it prone to stretching and deformation even at low temperatures. Therefore, when an inorganic oxide layer is formed on a polyethylene film by a method such as vapor deposition to impart high gas barrier properties, the inorganic oxide layer on the polyethylene film is prone to cracking during or after processing, making it difficult to maintain high gas barrier properties. Furthermore, inorganic oxide layers formed on polyethylene film are particularly prone to cracking when bent. Therefore, there is a need for the development of laminates that can maintain high gas barrier properties even after bending.

[0006] The present disclosure has been made in view of the above circumstances, and aims to provide a gas barrier laminate that is mainly composed of a polyolefin-based film and that can maintain high gas barrier properties even after bending. Another aim of the present disclosure is to provide a packaging bag using the gas barrier laminate. [Means for solving the problem]

[0007] In order to achieve the above object, the present disclosure provides a gas barrier laminate having a structure in which a substrate layer containing a polyolefin, an undercoat layer, an inorganic oxide layer, a gas barrier adhesive layer, and a resin layer containing a polyolefin are laminated in this order.

[0008] When attempting to impart gas barrier properties by forming an inorganic oxide layer on a polyolefin-containing substrate layer, the thin, hard, and brittle inorganic oxide layer tends to easily crack on the soft, stretchable substrate layer, resulting in insufficient gas barrier properties. In contrast, the gas barrier laminate of the present disclosure includes an undercoat layer on the substrate layer for providing the inorganic oxide layer, allowing the inorganic oxide layer to be formed uniformly on the undercoat layer and preventing cracking of the inorganic oxide layer due to stretching of the substrate layer. Furthermore, the gas barrier laminate of the present disclosure includes a gas barrier adhesive layer on the inorganic oxide layer, which protects the inorganic oxide layer and allows the gas barrier adhesive layer to withstand bending tests as a packaging material. However, if the layer provided on the inorganic oxide layer is an adhesive layer that does not have gas barrier properties or a barrier layer that does not function as an adhesive, it is difficult to maintain high gas barrier properties after bending tests. By providing an adhesive layer having gas barrier properties on the inorganic oxide layer, it is possible to suppress cracking of the inorganic oxide layer when bent, and even if minor cracks occur in part of the inorganic oxide layer, the gas barrier adhesive layer fills the minor cracks, thereby suppressing a decrease in gas barrier properties. Furthermore, since both the substrate layer and the resin layer of the gas barrier laminate of the present disclosure are layers containing polyolefin, it is possible to realize a mono-material structure.

[0009] In the gas barrier laminate, the thickness of the gas barrier adhesive layer may be 50 times or more the thickness of the inorganic oxide layer. The gas barrier adhesive layer not only functions as an adhesive but also as a protective coating layer, and therefore can be used at a thickness 50 times or more the thickness of the inorganic oxide layer. When the gas barrier adhesive layer has the above thickness, cracking of the inorganic oxide layer can be more sufficiently suppressed, and the gas barrier properties of the gas barrier laminate can be further improved. Furthermore, when the gas barrier adhesive layer has the above thickness, cushioning properties can be obtained that absorb external impacts, and cracking of the inorganic oxide layer due to impacts can be prevented.

[0010] In the gas barrier laminate, the gas barrier adhesive layer has an oxygen permeability of 100 cc / m 2 ·day·atm or less. This can further improve the gas barrier properties of the gas barrier laminate and further suppress deterioration of the gas barrier properties after bending. Furthermore, when minor cracks occur in the inorganic oxide layer due to bending or the like and the gas barrier adhesive layer fills in the gaps to fill them, by having the oxygen permeability of the gas barrier adhesive layer be within the above range, deterioration of the gas barrier properties can be further suppressed.

[0011] In the gas barrier laminate, the surface of the gas barrier adhesive layer may have a logarithmic decrement at 30°C of 0.1 or less, as measured using a rigid pendulum physical property tester. When the surface of the gas barrier adhesive layer has a logarithmic decrement of 0.1 or less, the gas barrier properties of the gas barrier laminate can be further improved and deterioration of the gas barrier properties after bending can be further suppressed. When the logarithmic decrement is low, molecules on the surface of the gas barrier adhesive layer become less mobile, making it difficult for gas molecules such as oxygen to pass through, which is thought to result in higher gas barrier properties.

[0012] In the gas barrier laminate, the gas barrier adhesive layer may be a layer formed using an epoxy adhesive. Because epoxy resins have a molecular structure that makes it easy to form dense films, gas barrier adhesive layers formed using epoxy adhesives tend to exhibit higher gas barrier properties. In particular, gas barrier adhesive layers formed using epoxy adhesives and having a logarithmic decrement of 0.1 or less tend to exhibit even better gas barrier properties.

[0013] In the gas barrier laminate, the inorganic oxide layer may contain silicon oxide. An inorganic oxide layer containing silicon oxide is likely to suppress deterioration of gas barrier properties due to stretching or bending, and therefore is likely to suppress deterioration of gas barrier properties of a gas barrier laminate using a base layer containing a polyolefin, which is prone to deformation.

[0014] In the gas barrier laminate, the resin layer may be a sealant layer, and the difference in heat fusion temperature between the base layer and the sealant layer may be 10° C. or more. By providing a difference in heat fusion temperature of 10° C. or more between the base layer and the sealant layer, it becomes easy to form the gas barrier laminate into a packaging bag or the like by heat sealing.

[0015] In the gas barrier laminate, the difference in Tg between the subbing layer and the gas barrier adhesive layer may be 100° C. or less. By keeping the difference in Tg between the subbing layer and the gas barrier adhesive layer at 100° C. or less, cracking of the inorganic oxide layer disposed between the subbing layer and the gas barrier adhesive layer due to stress applied thereto can be suppressed during heat sealing or processing of the gas barrier laminate.

[0016] The gas barrier laminate may have a structure in which a printed layer is further laminated. The gas barrier laminate may also have a structure in which the resin layer is a first resin layer, and a second resin layer containing a polyolefin is further laminated separately from the first resin layer. When the gas barrier laminate has a printed layer but no second resin layer, the printed layer is usually formed on the surface of the base layer opposite the undercoat layer.

[0017] When the gas barrier laminate includes a second resin layer, the difference in heat fusion temperature between the two furthest layers of the three layers of the base layer, the first resin layer, and the second resin layer may be 10° C. or more, which makes it easy to form the gas barrier laminate into a packaging bag or the like by heat sealing.

[0018] The present disclosure also provides a packaging bag produced by forming the above-described gas barrier laminate. [Effects of the Invention]

[0019] According to the present disclosure, it is possible to provide a gas barrier laminate that maintains high gas barrier properties even after bending, even when the gas barrier laminate is mainly composed of a polyolefin-based film.The present disclosure also provides a packaging bag using the gas barrier laminate. [Brief explanation of the drawings]

[0020] [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 gas barrier laminate according to one embodiment. [Figure 3] FIG. 3 is a schematic cross-sectional view showing a gas barrier laminate according to one embodiment. [Figure 4] FIG. 4 is a schematic cross-sectional view showing a gas barrier laminate according to one embodiment. [Figure 5] FIG. 5 is a schematic cross-sectional view showing a gas barrier laminate according to one embodiment. [Figure 6] FIG. 6 is a perspective view showing one embodiment of a packaging bag with a spout. [Figure 7] FIG. 7 is a front view showing one embodiment of a tube container. DETAILED DESCRIPTION OF THE INVENTION

[0021] Preferred embodiments of the present disclosure will be described in detail below, with reference to the drawings where appropriate. In the drawings, identical or corresponding parts are designated by the same reference numerals, and duplicate explanations will be omitted. Furthermore, the dimensional ratios of the drawings are not limited to those shown.

[0022] <Gas barrier laminate> Fig. 1 is a schematic cross-sectional view showing a gas barrier laminate according to one embodiment. The gas barrier laminate 10 shown in Fig. 1 comprises, in this order, a substrate layer 1, an undercoat layer 2, an inorganic oxide layer 3, a gas barrier adhesive layer 4, and a resin layer (first resin layer) 5. Both the substrate layer 1 and the first resin layer 5 contain polyolefin.

[0023] Fig. 2 is a schematic cross-sectional view showing a gas barrier laminate according to another embodiment. The gas barrier laminate 20 shown in Fig. 2 further includes a printed layer 6 on the outer side of the base layer (on the side opposite to the undercoat layer 2) of the gas barrier laminate 10 shown in Fig. 1.

[0024] Fig. 3 is a schematic cross-sectional view showing a gas barrier laminate according to another embodiment. The gas barrier laminate 30 shown in Fig. 3 has a structure in which a printed layer 6 and a second resin layer 7 are laminated on the outer side of the base layer of the gas barrier laminate 10 shown in Fig. 1 via an adhesive layer 8. The second resin layer 7 contains polyolefin.

[0025] Fig. 4 is a schematic cross-sectional view showing a gas barrier laminate according to another embodiment. The gas barrier laminate 40 shown in Fig. 4 includes, in this order, a first resin layer 5, a printed layer 6, a gas barrier adhesive layer 4, an inorganic oxide layer 3, an undercoat layer 2, a substrate layer 1, an adhesive layer 8, and a second resin layer 7.

[0026] Fig. 5 is a schematic cross-sectional view showing a gas barrier laminate according to another embodiment. The gas barrier laminate 50 shown in Fig. 5 has a structure in which a printed layer 6, an adhesive layer 8, and a second resin layer 7 are laminated on the outer side of the first resin layer 5 (on the side opposite to the gas barrier adhesive layer 4) of the gas barrier laminate 10 shown in Fig. 1.

[0027] When a packaging bag or the like is produced using the gas barrier laminates 10, 20, 30, the first resin layer 5 can be made to function as a sealant layer. When a packaging bag or the like is produced using the gas barrier laminates 40, 50, the second resin layer 7 can be made to function as a sealant layer. Each layer will be described below.

[0028] [Base material layer 1] The base layer 1 is a film that serves as a support and contains polyolefin. The content of polyolefin in the base layer 1 may be 50% by mass or more, 80% by mass or more, or even 100% by mass based on the total mass of the base layer 1. Using polyolefin as the material for the base layer 1 is preferable from the viewpoint of recyclability. Furthermore, the higher the content of polyolefin in the base layer 1, the more improved the recyclability.

[0029] The base layer 1 may be made of a polyolefin film. Examples of polyolefins include polyethylene (PE), polypropylene (PP), and polybutene (PB). The polyolefin may be polyethylene. Examples of polyolefins 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.

[0030] From the viewpoint of retort resistance, the polyolefin is preferably polypropylene. Here, the polypropylene may be homopolypropylene or a propylene copolymer. From the viewpoint of adhesion and barrier properties, a coating layer such as an easy-adhesion layer containing a propylene copolymer may be provided on the lamination surface of the base layer 1 (the surface on which the subbing layer 2 is laminated). The easy-adhesion layer may be provided between the base layer 1 and the subbing layer 2.

[0031] The density of the polyolefin contained in the base layer 1 is 0.900 g / cm 3 It may be 0.910 g / cm or more. 3 In addition, when the polyolefin contained in the base layer 1 is polyethylene, its density may be 0.930 g / cm or more. 3 or more, and may be 0.935 g / cm 3 or more, and may be 0.945 g / cm 3 The density of the polyolefin may be 0.935 g / cm or more. 3 This makes it easy to prevent the base layer 1 from stretching and wrinkling during rolling, and also makes it easy to prevent cracks from occurring in the inorganic oxide layer 3. The base layer 1 may contain biomass-derived or recycled polyolefin.

[0032] The base layer 1 may be configured as a multilayer structure having a plurality of layers (films) each containing polyolefins with different densities. The base layer 1 is preferably multilayered in consideration of the processability, rigidity, stiffness, heat resistance, powder shedding during transport, etc. of the film that constitutes the base layer 1. The film that constitutes the base layer 1 can be produced by appropriately selecting and using high-density polyolefin, medium-density polyolefin, low-density polyolefin, etc. When the density of the film used as the base layer 1 was measured, the density was 0.900 g / cm. 3 or more is preferable. Furthermore, the contents of slip agents, antistatic agents, etc. may be varied in each layer. The base layer 1 having multiple layers can be laminated into a film by extrusion coating, co-extrusion coating, sheet molding, co-extrusion blow molding, etc. The total thickness of the base layer 1 having multiple layers is preferably about 10 to 100 μm, more preferably 15 to 50 μm.

[0033] The film constituting the base layer 1 may be a stretched film or a non-stretched film. However, from the viewpoints of impact resistance, heat resistance, water resistance, dimensional stability, ease of tearing, etc., the film constituting the base layer 1 may be a stretched film. When a printing layer 6 is provided on the base layer 1, a stretched film has the advantage of being easier to print on. Furthermore, when the base layer 1 is a stretched film, the gas barrier laminate can be more suitably used for applications that require boiling treatment. 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.

[0034] The base layer 1 preferably has a heat shrinkage rate of 3% or less, more preferably 2% or less, and even more preferably 1.5% or less in the running direction (MD) and the perpendicular direction (TD) after heating at 100° C. for 15 minutes. When the heat shrinkage rate of the base layer 1 is within the above range, the base layer 1 is easily prevented from stretching and wrinkling during rolling, and the inorganic oxide layer 3 is easily prevented from cracking.

[0035] Here, the heat shrinkage rate (%) is a value calculated by the following formula. Heat shrinkage rate (%) = {(length before heating - length after heating) / length before heating} x 100 The procedure for measuring the heat shrinkage rate is as follows. (1) The substrate layer 1 is cut into a 20 cm x 20 cm sample to be used as a measurement sample. (2) Draw a 10 cm line in the MD or TD direction on the measurement sample (the length before heating). (3) Heat the measurement sample at 100°C for 15 minutes. (4) The length of the written line in the MD or TD direction is measured (length after heating). (5) Calculate the thermal shrinkage rate using the above formula.

[0036] There are no particular limitations on the thickness of the base layer 1. Depending on the application, the thickness can be set to 6 to 200 μm, but from the viewpoint of obtaining excellent impact resistance and excellent gas barrier properties, the thickness may be set to 9 to 50 μm or 12 to 38 μm.

[0037] In order to improve adhesion to the undercoat layer 2 and the inorganic oxide layer 3, the surface of the substrate layer 1 may be subjected to various pretreatments such as corona treatment, plasma treatment, low-temperature plasma treatment, flame treatment, chemical treatment, solvent treatment, and ozone treatment, or a coating layer such as an easy-adhesion layer may be provided, as long as the barrier performance is not impaired.

[0038] The base layer 1 may contain additives such as fillers, antiblocking agents, antistatic agents, plasticizers, lubricants, antioxidants, etc. These additives may be used alone or in combination of two or more.

[0039] [Sublayer 2] An undercoat layer (anchor coat layer) 2 is provided on the surface of the substrate layer 1 on which the inorganic oxide layer 3 is to be laminated. The undercoat layer 2 has the effects of improving the adhesion between the substrate layer 1 and the inorganic oxide layer 3, improving the smoothness of the surface of the substrate layer 1, and suppressing the occurrence of cracks in the inorganic oxide layer 3 due to elongation of the substrate layer 1. The improved smoothness makes it easier to form the inorganic oxide layer 3 uniformly without defects, and makes it easier to exhibit high barrier properties. The undercoat layer 2 can be formed using a composition for forming an undercoat layer (anchor coat agent).

[0040] Examples of resins used in anchor coating agents include acrylic resins, epoxy resins, acrylic urethane resins, polyester polyurethane resins, and polyether polyurethane resins. From the viewpoints of heat resistance and interlayer adhesive strength, acrylic urethane resins and polyester polyurethane resins are preferred as resins used in anchor coating agents. The undercoat layer 2 can be formed using these resins or anchor coating agents containing components that react to form these resins.

[0041] The thickness of the undercoat layer 2 is not particularly limited, but is preferably in the range of 0.01 to 5 μm, more preferably in the range of 0.03 to 3 μm, and particularly preferably in the range of 0.05 to 2 μm. If the thickness of the undercoat layer 2 is equal to or greater than the above lower limit, more sufficient interlayer adhesive strength tends to be obtained, while if the thickness is equal to or less than the above upper limit, desired gas barrier properties tend to be readily exhibited.

[0042] The method for applying the undercoat layer 2 to the substrate layer 1 can be any known application method without any particular limitation, and examples thereof include immersion (dipping) methods, and methods using a spray, coater, printer, brush, etc. Examples of the types of coaters and printers used in these methods and the application methods thereof include gravure coaters such as direct gravure, reverse gravure, kiss reverse gravure, and offset gravure, reverse roll coaters, microgravure coaters, coaters with chamber doctor, air knife coaters, dip coaters, bar coaters, comma coaters, and die coaters.

[0043] The coating amount of the undercoat layer 2 is 1 m after the anchor coating agent is applied and dried. 2 Mass per unit is 0.01 to 5 g / m 2 It is preferable that the density is 0.03 to 3 g / m 2 It is more preferable that the thickness is 1m after the anchor coating agent is applied and dried. 2 When the mass per unit area is equal to or greater than the lower limit, film formation tends to be sufficient, whereas when the mass per unit area is equal to or less than the upper limit, the film tends to be sufficiently dried and the solvent tends not to remain.

[0044] The method for drying the undercoat layer 2 is not particularly limited, but examples thereof include natural drying, drying in an oven set at a predetermined temperature, and using a dryer attached to the coater, such as an arch dryer, floating dryer, drum dryer, infrared dryer, etc. Furthermore, the drying conditions can be appropriately selected depending on the drying method, and for example, in the method of drying in an oven, drying at a temperature of 60 to 100°C for about 1 second to 2 minutes is preferred.

[0045] A polyvinyl alcohol resin can be used instead of the above-mentioned resins for the undercoat layer 2. The polyvinyl alcohol resin may be any resin having a vinyl alcohol unit formed by saponifying a vinyl ester unit, and examples thereof include polyvinyl alcohol (PVA) and ethylene-vinyl alcohol copolymer (EVOH).

[0046] Examples of PVA include resins prepared 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. PVA may also be modified PVA, which has been copolymerized or post-modified. Modified PVA can be obtained, for example, by copolymerizing a vinyl ester with an unsaturated monomer copolymerizable with the vinyl ester, followed by saponification. Examples of unsaturated monomers copolymerizable with vinyl ester include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, and α-octadecene; hydroxyl-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; diacetone acrylamide, acrylic acid, and the like. 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-vinylpyrrolidone, 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, and vinylene carbonate.

[0047] The degree of polymerization of PVA is preferably 300 to 3000. If the degree of polymerization is 300 or more, the barrier property is likely to be improved, and if it is 3000 or less, it is likely to be possible to prevent the viscosity from becoming too high and the coating suitability from decreasing. The saponification degree of PVA is preferably 90 mol% or more, more preferably 95 mol% or more, and even more preferably 99 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).

[0048] 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.

[0049] The degree of polymerization of EVOH is preferably 300 to 3000. If the degree of polymerization is 300 or more, the barrier property is likely to be improved, and if it is 3000 or less, it is likely to be possible to prevent the viscosity from becoming too high and the coating suitability from decreasing. The saponification degree of the vinyl ester component of EVOH is preferably 90 mol% or more, more preferably 95 mol% or more, and even more preferably 99 mol% or more. The saponification degree of EVOH may be 100 mol% or less, or 99.9 mol% or less. The saponification degree of EVOH can be determined by nuclear magnetic resonance ( 1 1 H-NMR measurement is performed, and the peak area of ​​the hydrogen atoms contained in the vinyl ester structure and the peak area of ​​the hydrogen atoms contained in the vinyl alcohol structure are used to determine the chromaticity.

[0050] 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 25 mol% or more. The ethylene unit content of EVOH is preferably 65 mol% or less, more preferably 55 mol% or less, and even more preferably 50 mol% or less. When the ethylene unit content is 10 mol% or more, good gas barrier properties or dimensional stability can be maintained under high humidity conditions. On the other hand, when the ethylene unit content is 65 mol% or less, good gas barrier properties can be achieved. The ethylene unit content of EVOH can be determined by NMR.

[0051] When a polyvinyl alcohol resin is used as the undercoat layer 2, the undercoat layer 2 can be formed by coating a polyvinyl alcohol resin solution or by multi-layer extrusion.

[0052] [Inorganic oxide layer 3] Examples of materials constituting the inorganic oxide layer 3 include inorganic oxides such as 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 that the inorganic oxide layer 3 be a layer using silicon oxide. By using the inorganic oxide layer 3, high barrier properties can be obtained with an extremely thin layer that does not affect the recyclability of the gas barrier laminate.

[0053] The O / Si ratio of the inorganic oxide layer 3 is preferably 1.7 or higher. When the O / Si ratio is 1.7 or higher, the content of metallic Si is suppressed, making it easier to achieve good transparency. Furthermore, the O / Si ratio is preferably 2.0 or lower. When the O / Si ratio is 2.0 or lower, the crystallinity of SiO is increased, preventing the inorganic oxide layer from becoming too hard and achieving good tensile strength. This can prevent cracks from occurring in the inorganic oxide layer 3 when laminating the gas barrier adhesive layer 4. Furthermore, even after forming into a packaging bag, the base layer 1 may shrink due to heat during the boiling treatment. However, when the O / Si ratio is 2.0 or lower, the inorganic oxide layer can easily follow this shrinkage and prevent a decrease in barrier properties. To more fully achieve these effects, the O / Si ratio of the inorganic oxide layer 3 is preferably 1.75 to 1.9, more preferably 1.8 to 1.85.

[0054] The O / Si ratio of the inorganic oxide layer 3 can be determined by X-ray photoelectron spectroscopy (XPS). For example, the measurement can be performed using an X-ray photoelectron spectrometer (manufactured by JEOL Ltd., product name: JPS-90MXV) with a non-monochromated MgKα (1253.6 eV) X-ray source and an X-ray output of 100 W (10 kV-10 mA). For quantitative analysis to determine the O / Si ratio, relative sensitivity factors of 2.28 for O1s and 0.9 for Si2p can be used.

[0055] The thickness of the inorganic oxide layer 3 is preferably 10 nm or more and 50 nm or less. A thickness of 10 nm or more can provide sufficient gas barrier properties. Furthermore, a thickness of 50 nm or less can prevent cracks from occurring due to deformation caused by internal stress in the thin film, thereby preventing a decrease in gas barrier properties. Furthermore, a thickness of 50 nm or less is also preferable from an economical standpoint, since it is easy to prevent increases in costs due to an increase in the amount of material used and an increase in the film formation time. From the same viewpoint as above, the thickness of the inorganic oxide layer is more preferably 20 nm or more and 40 nm or less.

[0056] The inorganic oxide layer 3 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.

[0057] 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.

[0058] [Gas barrier adhesive layer 4] The gas barrier adhesive layer 4 bonds the inorganic oxide layer 3 and the first resin layer 5 together, and also protects the inorganic oxide layer 3, thereby preventing the inorganic oxide layer 3 from cracking when bent.

[0059] The gas barrier adhesive layer 4 is a layer having gas barrier properties. By providing the gas barrier adhesive layer 4, the gas barrier properties of the gas barrier laminate can be improved. The oxygen permeability of the gas barrier adhesive layer 4 is 150 cc / m 2 ·day·atm or less is preferable, and 100cc / m 2 ·day·atm or less is more preferable, and 80cc / m 2 ·day·atm or less is more preferable, and 50cc / m 2 By having an oxygen permeability within the above range, the gas barrier properties of the gas barrier laminate can be sufficiently improved, and even if minor cracks occur in the inorganic oxide layer 3, the gas barrier adhesive layer 4 can fill in the gaps and fill in the cracks, thereby preventing a decrease in the gas barrier properties.

[0060] The gas barrier adhesive layer 4 is formed using an adhesive that can exhibit gas barrier properties after curing. Examples of adhesives that can be used to form the gas barrier adhesive layer 4 include epoxy adhesives and polyester / polyurethane adhesives. Specific examples of adhesives that can exhibit gas barrier properties after curing include "Maxieve" manufactured by Mitsubishi Gas Chemical Company, Inc. and "Paslim" manufactured by DIC Corporation.

[0061] The logarithmic decrement of the surface of the gas barrier adhesive layer 4 at 30°C, measured using a rigid pendulum physical property tester, is preferably 0.1 or less, more preferably 0.05 or less, and even more preferably 0.03 or less. When the logarithmic decrement of the surface of the gas barrier adhesive layer 4 is within the above range, the gas barrier properties of the gas barrier laminate can be further improved, and deterioration of the gas barrier properties after bending can be further suppressed.

[0062] The thickness of the gas barrier adhesive layer 4 is preferably at least 50 times the thickness of the inorganic oxide layer 3. When the thickness of the adhesive layer 4 is within the above range, cracking of the inorganic oxide layer 3 can be more sufficiently suppressed, and the gas barrier properties of the gas barrier laminate can be further improved. Furthermore, when the thickness of the gas barrier adhesive layer 4 is within the above range, cushioning properties that absorb external impacts can be obtained, and cracking of the inorganic oxide layer 3 due to impacts can be prevented. On the other hand, from the viewpoints of maintaining the flexibility of the gas barrier laminate, processability, and cost, the thickness of the gas barrier adhesive layer 4 is preferably no more than 300 times the thickness of the inorganic oxide layer 3.

[0063] The thickness of the gas barrier adhesive layer 4 is preferably 0.1 to 20 μm, more preferably 0.5 to 10 μm, and even more preferably 1 to 5 μm. When the thickness of the gas barrier adhesive layer 4 is equal to or greater than the above-mentioned lower limit, cracking of the inorganic oxide layer 3 can be more sufficiently suppressed, and the gas barrier properties of the gas barrier laminate can be further improved. Furthermore, when the thickness of the gas barrier adhesive layer 4 is equal to or greater than the above-mentioned lower limit, cushioning properties that absorb external impacts can be obtained, and cracking of the inorganic oxide layer 3 due to impacts can be prevented. On the other hand, when the thickness of the gas barrier adhesive layer 4 is equal to or less than the above-mentioned upper limit, the flexibility of the gas barrier laminate tends to be sufficiently maintained.

[0064] The adhesive for forming the gas barrier adhesive layer 4 can be applied by, for example, bar coating, dipping, roll coating, gravure coating, reverse coating, air knife coating, comma coating, die coating, screen printing, spray coating, gravure offset, or the like. The temperature for drying the coating film formed by applying this adhesive can be, for example, 30 to 200°C, and preferably 50 to 180°C. The temperature for curing the coating can be, for example, room temperature to 70°C, and preferably 30 to 60°C. By keeping the drying and curing temperatures within the above ranges, the occurrence of cracks in the inorganic oxide layer 3 and the gas barrier adhesive layer 4 can be further suppressed, and excellent gas barrier properties can be achieved.

[0065] The gas barrier adhesive layer 4 and the inorganic oxide layer 3 are preferably in direct contact (with no other layer interposed therebetween) from the viewpoint of preventing cracking of the inorganic oxide layer 3. Therefore, the gas barrier adhesive layer 4 is preferably formed by applying the above adhesive onto the inorganic oxide layer 3, and drying and curing it. Similarly, the inorganic oxide layer 3 and the undercoat layer 2 are preferably in direct contact (with no other layer interposed therebetween) from the viewpoint of preventing cracking of the inorganic oxide layer 3.

[0066] [First resin layer 5] The first resin layer 5 is a layer containing polyolefin. The content of polyolefin in the first resin layer 5 may be 50% by mass or more, 80% by mass or more, or 100% by mass based on the total amount of the first resin layer 5. The first resin layer 5 may contain biomass-derived or recycled polyolefin. The first resin layer 5 may be a sealant layer. The sealant layer is a layer that imparts heat-sealing sealability to the gas barrier laminate. The sealant layer may be made of a polyolefin film. The polyolefin may be polyethylene.

[0067] Among thermoplastic resins, polyolefin resins are commonly used as the material for the sealant layer, and specific examples include ethylene resins such as low-density polyethylene resin (LDPE), medium-density polyethylene resin (MDPE), linear low-density polyethylene resin (LLDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-α-olefin copolymer, and ethylene-(meth)acrylic acid copolymer, as well as blends of polyethylene and polybutene, and polypropylene resins such as homopolypropylene resin (PP), propylene-ethylene random copolymer, propylene-ethylene block copolymer, and propylene-α-olefin copolymer. These thermoplastic resins can be selected appropriately depending on the intended use and temperature conditions such as boiling treatment.

[0068] The sealant layer may contain various additives such as a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, and a tackifier.

[0069] The thickness of the sealant layer is determined depending on the weight of the contents, the shape of the packaging bag, etc., but is preferably about 30 to 150 μm.

[0070] The sealant layer can be formed by any of the known lamination methods, such as a method in which a film-like sealant layer made of the above-mentioned thermoplastic resin is bonded using the adhesive used to form the gas barrier adhesive layer 4 described above, a dry lamination method in which the layers are bonded using an adhesive such as a one-component curing or two-component curing urethane adhesive, a non-solvent dry lamination method in which a film-like sealant layer is bonded using a solvent-free adhesive, or an extrusion lamination method in which the above-mentioned thermoplastic resin is heated and melted, extruded into a curtain shape, and bonded together.

[0071] On the other hand, when the first resin layer 5 is not a sealant layer, the first resin layer 5 can have the same configuration as the base layer 1.

[0072] [Print layer 6] The printing layer 6 is provided in a position visible from the outside of the gas barrier laminate for the purpose of displaying information about the contents, identifying the contents, or improving the design of the packaging bag. The printing method and printing ink are not particularly limited, and are appropriately selected from known printing methods and printing inks taking into consideration printability on the film, design characteristics such as color tone, adhesion, and safety as a food container. Examples of printing methods that can be used include gravure printing, offset printing, gravure-offset printing, flexographic printing, and inkjet printing. Among these, gravure printing is preferred from the standpoints of productivity and high-resolution images. Biomass ink or biodegradable ink may be used from an environmentally friendly perspective.

[0073] In order to improve the adhesion of the printing layer 6, the surface of the layer (substrate layer 1, first resin layer 5 or second resin layer 7) that forms the printing layer 6 may be subjected to various pretreatments such as corona treatment, plasma treatment or flame treatment, or a coating layer such as an easy-adhesion layer may be provided.

[0074] [Second resin layer 7] The second resin layer 7 is a layer containing polyolefin. The content of polyolefin in the second resin layer 7 may be 50% by mass or more, 80% by mass or more, or 100% by mass based on the total mass of the second resin layer 7. The second resin layer 7 may contain biomass-derived or recycled polyolefin. The second resin layer 7 may be a sealant layer. The configuration of the sealant layer is as described above.

[0075] On the other hand, when the second resin layer 7 is not a sealant layer, the second resin layer 7 can have the same configuration as the base material layer 1.

[0076] Here, there are no particular limitations on the positions where the printed layer 6 and the second resin layer 7 are laminated. The second resin layer 7 may be formed, for example, on the surface of the base layer 1 opposite the undercoat layer 2, or on the surface of the first resin layer 5 opposite the gas barrier adhesive layer 4, or may be formed between the gas barrier adhesive layer 4 and the first resin layer 5. The second resin layer 7 may be laminated to another layer via an adhesive layer 8 made of a general adhesive.

[0077] The printed layer 6 may be formed, for example, on the surface of the base layer 1 opposite the undercoat layer 2, or on the surface of the first resin layer 5 opposite the gas barrier adhesive layer 4, or may be formed between the gas barrier adhesive layer 4 and the first resin layer 5. When the gas barrier laminate includes a second resin layer 7, the printed layer 6 may be formed on one surface of the second resin layer 7. In this case, the printed layer 6 may be formed on the second resin layer 7 in advance, and the second resin layer 7 with the printed layer 6 formed thereon may be laminated with another layer via the adhesive layer 8.

[0078] [Adhesive layer 8] Known adhesives can be used as the adhesive that constitutes the adhesive layer 8. Examples of adhesive materials that can be used include polyester-isocyanate resins, urethane resins, and polyether resins. The adhesive used to form the gas barrier adhesive layer 4 described above may also be used. From an environmental perspective, adhesives whose polymer components are derived from biomass or that are biodegradable may be used.

[0079] [Heat fusion temperature of each layer] In the gas barrier laminate described above, the difference in heat fusion temperature between the two furthest layers of the three layers, i.e., the base layer 1, the first resin layer 5, and the second resin layer 7, is preferably 10°C or more, more preferably 15°C or more, and even more preferably 20°C or more. When the gas barrier laminate is formed into a packaging bag or the like, one of the two furthest layers becomes a sealant layer. Therefore, by setting the difference in heat fusion temperature within the above range, it becomes easy to form the gas barrier laminate into a packaging bag or the like by heat sealing.

[0080] The heat fusion temperature of the base layer 1 is preferably 100°C or higher, and more preferably 120°C or higher. When the heat fusion temperature is 100°C or higher, the difference in melting point (heat fusion temperature difference) with the sealant layer increases, which tends to facilitate heat sealing. The heat fusion temperature of the base layer 1 is preferably higher than that of the sealant layer.

[0081] The heat fusion temperature of the layer of the first resin layer 5 and the second resin layer 7 used as the sealant layer is preferably adjusted depending on the type of polyolefin contained in the sealant layer. For example, when the polyolefin contained in the sealant layer is polyethylene, the heat fusion temperature of the sealant layer is preferably 130°C or lower, more preferably 110°C or lower. When the polyolefin contained in the sealant layer is polypropylene, the heat fusion temperature of the sealant layer is preferably 160°C or lower, more preferably 150°C or lower. When the heat fusion temperature is below the upper limit, the melting point difference (heat fusion temperature difference) between the layers of the first resin layer 5 and the second resin layer 7 that are not sealant layers and the base layer 1 increases, which tends to facilitate heat sealing. The preferred range of the heat fusion temperature of the layers of the first resin layer 5 and the second resin layer 7 that are not sealant layers is the same as that of the base layer 1.

[0082] Here, the heat fusion temperature of each layer is the heat sealing temperature of the measurement target layer, measured by a measurement method in accordance with JIS Z0238: 1998. Specifically, when two measurement target layers are superimposed and heated for one second at a pressure of 0.2 MPa using a heat seal tester to form a heat seal, the heat fusion temperature is the lowest temperature at which a heat seal that is heat-sealed and does not peel off can be formed.

[0083] [Glass transition temperature (Tg) of each layer] In the gas barrier laminate described above, the difference in Tg between the subbing layer 2 and the gas barrier adhesive layer 4 is preferably 100° C. or less, more preferably 80° C. or less, even more preferably 50° C. or less, and particularly preferably 30° C. or less. When this Tg difference is within the above range, cracking of the inorganic oxide layer 3, which is disposed between the subbing layer 2 and the gas barrier adhesive layer 4, due to stress applied thereto during heat sealing or processing of the gas barrier laminate can be more sufficiently prevented.

[0084] The Tg of the undercoat layer 2 is preferably 20 to 180° C., and more preferably 40 to 150° C. If the Tg is 180° C. or less, the undercoat layer 2 is not too hard and can easily conform to the flexibility of the substrate layer 1, which makes it easy to prevent the undercoat layer 2 from peeling off during lamination and reducing adhesion. On the other hand, if the Tg is 20° C. or more, the Tg is below room temperature, which makes it possible to prevent the undercoat layer 2 from becoming too soft and to prevent the inorganic oxide layer 3 from being unable to conform to the undercoat layer 2, which would cause cracks and reduce barrier properties.

[0085] The Tg of the gas barrier adhesive layer 4 is preferably 20 to 180° C., and more preferably 40 to 150° C. If the Tg is 180° C. or less, the gas barrier adhesive layer 4 is not too hard and can easily conform to the flexibility of the substrate layer 1, making it easier to prevent the gas barrier adhesive layer 4 from peeling off when laminated, resulting in a decrease in adhesion. On the other hand, if the Tg is 20° C. or more, the Tg is below room temperature, making it easier to prevent the molecules that make up the gas barrier adhesive layer 4 from moving at room temperature, making it possible to prevent insufficient expression of barrier properties.

[0086] The Tg of each layer can be measured, for example, by the following method. The composition (coating liquid) for forming each layer is placed in a container, and the solvent is removed and cured at 60°C for one day. Next, the cured product is removed and measured using a differential scanning calorimeter. The initial temperature is set to 0°C, and the product is held at 0°C for 5 minutes. After that, the product is continuously heated to 200°C at a rate of 10°C / min. The product is then cooled and held at 0°C for 5 minutes. The product is then continuously heated to 200°C at a rate of 10°C / min. The peak observed under the measurement conditions, known as the second run, is taken as the Tg. When measuring using a differential scanning calorimeter, the coating liquid is cured in a container, and the peak that appears during the initial heating is significantly affected by the solvent and the uncured material, making it difficult to determine the Tg. Therefore, the peak obtained from the second run is taken as the Tg of each layer.

[0087] As described above, all of the films constituting the gas barrier laminate can be polyolefin films. Such a gas barrier laminate can be said to be a monomaterial packaging material that is highly recyclable. From this perspective, the total mass of components other than the polyolefin component (e.g., adhesives and ink components) can be 10% by mass or less, and may be 7.5% by mass or less, of the total mass of the gas barrier laminate.

[0088] The thickness of the gas barrier laminate can be appropriately determined depending on the application, and can be, for example, 0.01 to 10 mm, preferably 0.1 to 1.0 mm.

[0089] The gas barrier laminate can be suitably used for various applications, such as packaging products such as containers and bags, sheet molded products such as decorative sheets and trays, optical films, resin plates, various label materials, lid materials, and laminated tubes, and is particularly suitable for packaging products such as pillow bags, standing pouches, three-side sealed bags, and four-side sealed bags.

[0090] <Packaging bag> The packaging bag is obtained by forming the gas barrier laminate described above. The packaging bag may be formed into a bag shape by folding one gas barrier laminate in half so that the sealant layers face each other and then heat-sealing three sides, or may be formed into a bag shape by stacking two gas barrier laminates so that the sealant layers face each other and then heat-sealing four sides. The packaging bag can contain contents such as food, medicine, etc. The packaging bag can be subjected to heat sterilization treatment such as retort treatment or boiling treatment.

[0091] Retort processing is a method of sterilizing microorganisms such as mold, yeast, and bacteria under pressure, generally for the preservation of food, medicine, etc. Typically, packaging bags containing food, etc. are pressure sterilized at 105-140°C, 0.15-0.30 MPa, and for 10-120 minutes. Retort equipment comes in two types: steam type, which uses heated steam, and hot water type, which uses pressurized heated water, and is used appropriately depending on the sterilization conditions of the food, etc. that will be contained.

[0092] Boiling is a moist heat sterilization method for preserving foods, medicines, etc. Typically, although depending on the contents, packaging bags containing foods, etc. are subjected to moist heat sterilization under conditions of 60 to 100°C and atmospheric pressure for 10 to 120 minutes. Boiling is usually performed using a hot water bath at 100°C or less. Methods include a batch method in which the bag is immersed in a hot water bath at a constant temperature and treated for a certain period of time before being removed, and a continuous method in which the bag is passed through a tunnel-type hot water bath for treatment. The packaging bag of this embodiment can also be used suitably for applications requiring boiling treatment.

[0093] The packaging bag may also have a shape with a bent portion (folded portion) such as a standing pouch, etc. The packaging bag of the present embodiment can maintain high gas barrier properties even when it has a shape with a bent portion.

[0094] Another form of packaging bag is a packaging bag with a stopper. Examples of the structure of a packaging bag with a stopper include a structure in which the stopper is sandwiched and fixed between two gas barrier laminates that form the packaging bag, or a structure in which a hole is drilled on one side of the packaging bag and a spout is glued and fixed. The spout can be provided on the top surface of the packaging bag, or diagonally above the packaging bag, or on the side or bottom surface of the packaging bag. When the contents are liquid or gel-like food, a straw that reaches the bottom of the container may be provided in addition to the spout (so-called spout) so that the contents can be directly poured into the mouth and dispensed.

[0095] Fig. 6 is a perspective view showing one embodiment of a spouted packaging bag (a spouted gusset bag). The spouted packaging bag 100 shown in Fig. 6 has a structure in which a spout 104 is sandwiched and fixed in a seal portion 130 of a gas barrier laminate that forms a packaging bag 140, and the spout 104 is provided with a straw 105 that reaches the bottom of the container. The spouted packaging bag 100 can be sealed by closing a spout cap 104a. The packaging bag 140 that constitutes the spouted packaging bag 100 may be a gusset bag that can stand on its own by expanding the bottom of the bag when filled with contents, resulting in a downwardly bulging shape.

[0096] Furthermore, since the gas barrier laminate of this embodiment comprises a base layer containing a polyolefin and a resin layer containing a polyolefin, it is flexible and maintains high gas barrier properties even after bending, and therefore can be suitably used as a squeeze pouch. The squeeze pouch may be provided with a resealable stopper, or may have a structure in which a dispensing outlet is provided by cutting off the pouch for disposable use.

[0097] Another form of packaging bag with a spout is a bag-in-box, in which a bag (inner bag) containing a liquid such as a soft drink or alcoholic beverage is placed in a carton (outer box). The gas barrier laminate of this embodiment can be used for the bag in the bag-in-box, particularly for the bag body equipped with a spout (tube) for pouring.

[0098] In the case of any of the above-mentioned packaging bags with a spout, it is preferable, from the viewpoint of improving recyclability, to use the same resin for the spout portion or the entire spout including the cap as for the base material layer and resin layer of the gas barrier laminate.

[0099] The gas barrier laminate of this embodiment can also be used in the body of a tube container. A tube container generally comprises a body made of the gas barrier laminate and a spout manufactured by extrusion molding. The spout comprises a stopper for discharging the contents and a shoulder for guiding the contents held in the body to the stopper.

[0100] Fig. 7 is a front view showing one embodiment of a tube container. The tube container 500 shown in Fig. 7 includes a body 510 made of a gas barrier laminate, a spout 520 attached to one end of the body 510, and a cap 530 attached to the spout 520. The body 510 is a tubular member formed by bonding the sealant layers of the gas barrier laminate together at a seal portion 513 and by closing a bottom portion 511 located at the other end opposite the end to which the spout 520 is attached, thereby allowing the contents to be contained. The spout 520 is composed of a spout 522 for discharging the contents and a shoulder portion 521 for guiding the contents held in the body 510 to the spout 522. The cap 530 is a member that allows the opening of the spout 522 to be closed and opened.

[0101] The gas barrier laminate of this embodiment has gas barrier properties and maintains high gas barrier properties even after bending, making it suitable for use in the body of the aforementioned tubular container, which is repeatedly folded and bent when squeezing out the contents. The layer structure of the body of a laminated tube, a type of tubular container, can be, for example, from the innermost layer, a first resin layer (sealant layer), a gas barrier adhesive layer, an inorganic oxide layer, a subbing layer, a substrate layer, an adhesive layer, and a second resin layer (sealant layer). Alternatively, the layer structure from the innermost layer can be the second resin layer (sealant layer), an adhesive layer, a substrate layer, a subbing layer, an inorganic oxide layer, a gas barrier adhesive layer, and a first resin layer (sealant layer). The printed layer may be provided on one side of the second resin layer and bonded to the substrate layer via an adhesive layer, or it may be provided on one side of the first resin layer and bonded to the inorganic oxide layer-forming surface of the substrate layer via a gas barrier adhesive layer. Alternatively, the tube body can be formed into a cylindrical shape by using the outermost first or second resin layer as a resin layer similar to the substrate layer, not intended for heat sealing, without being combined with a sealant layer. The innermost sealant layers are then bonded together at the end (sealed portion) of the gas barrier laminate, facing each other. In this case, since the outermost layer does not need to be a sealant layer, high-density polyethylene or polypropylene resin can be selected as the outermost layer, improving the durability and aesthetic appeal of the tube container. Furthermore, since a sealant layer typically requires a thickness of 60–100 μm, the use of a substrate layer (approximately 20–30 μm thick) that is not a sealant layer for the outermost layer can significantly reduce the amount of plastic used throughout the container. In a configuration in which the first resin layer is the innermost sealant layer, the outermost layer can be used as the substrate layer and the second resin layer can be omitted, further reducing the amount of plastic used throughout the tube container. In this case, a printed layer can be formed on the outermost substrate layer and protected with an overprint varnish. In a tube container that does not have a sealant layer on the outermost layer, the thickness of the laminate in the body is thinner than in a tube container that has sealant layers on both sides of the laminate, and therefore the stress on the gas barrier layer when bent is thought to be relatively large. However, the laminate of this embodiment has gas barrier properties and maintains high gas barrier properties even after bending, so it can be preferably used.The shape of the tube container can be such that the shoulder is not tapered but is perpendicular to the body so that the contents can be squeezed out to the last drop. Recyclability can be improved by using the same resin for the base layer and sealant layer of the gas barrier laminate. The materials for the spout and cap of the tube container are not particularly limited, but using the same resin as the base layer can further improve recyclability. In tube containers, an easily peelable film is sometimes attached to the outside of the spout to seal the opening until the first opening. The gas barrier laminate of this embodiment can also be used as a lid material for sealing such openings in combination with an easily peelable sealant. [Example]

[0102] The present disclosure will be explained in more detail by the following examples, but the present disclosure is not limited to these examples.

[0103] [Preparation of composition for forming undercoat layer] Acrylic polyol and tolylene diisocyanate were mixed so that the number of OH groups in the acrylic polyol was equal to the number of NCO groups in the tolylene diisocyanate, and the mixture was diluted with ethyl acetate to a total solids content (total amount of acrylic polyol and tolylene diisocyanate) of 5% by mass. β-(3,4-epoxycyclohexyl)trimethoxysilane was further added to the diluted mixture in an amount of 5 parts by mass per 100 parts by mass of the total amount of acrylic polyol and tolylene diisocyanate, and these were mixed to prepare a composition for forming an undercoat layer (anchor coating agent).

[0104] [Preparation of adhesive for forming gas barrier adhesive layer] (Adhesive A) Adhesive A, an epoxy adhesive, was prepared by mixing 23 parts by mass of a solvent made by mixing ethyl acetate and methanol in a mass ratio of 1:1 with 16 parts by mass of Maxieve C93T manufactured by Mitsubishi Gas Chemical Company, Inc. and 5 parts by mass of Maxieve M-100 manufactured by Mitsubishi Gas Chemical Company, Inc.

[0105] (Adhesive B) Adhesive B, a polyester-polyurethane adhesive, was prepared by mixing 100 parts by mass of Paslim VM001 manufactured by DIC Corporation, 25 parts by mass of Paslim VM108CP manufactured by DIC Corporation, and 25 parts by mass of ethyl acetate.

[0106] (Adhesive C) Adhesive C, a urethane adhesive, was prepared by mixing 100 parts by mass of Takelac A525 manufactured by Mitsui Chemicals, Inc., 11 parts by mass of Takenate A52 manufactured by Mitsui Chemicals, Inc., and 84 parts by mass of ethyl acetate.

[0107] (Adhesive D) Adhesive D, an epoxy adhesive, was prepared by mixing 100 parts by mass of AD393 manufactured by Toyo Ink Co., Ltd., 6 parts by mass of CAT-EP5 manufactured by Toyo Ink Co., Ltd., and 54 parts by mass of isopropyl alcohol.

[0108] [Example 1] (Formation of Undercoat Layer (Anchor Coat Layer)) The composition for forming the undercoat layer was applied with a wire bar to the corona-treated surface of an A4-size unstretched high-density polyethylene film (thickness: 32 μm) used as the base layer, and then dried and cured at 60°C to form a film with an acrylic urethane resin coating amount of 0.1 g / m 2 An undercoat layer having the formula:

[0109] (Formation of inorganic oxide layer (silica vapor deposition film)) A 30 nm thick transparent inorganic oxide layer (silica vapor deposition film) made of silicon oxide was formed on the undercoat layer using an electron beam heating vacuum deposition apparatus. The vapor deposition material type was adjusted to form a vapor deposition film with an O / Si ratio of 1.8.

[0110] (Preparation of gas barrier laminate) Adhesive A was applied to the inorganic oxide layer using a wire bar and dried at 60°C to form a 3µm thick gas barrier adhesive layer, followed by laminating a 60µm thick unstretched film (manufactured by Mitsui Chemicals Tocello, Inc., product name: TUX-MCS) made of linear low-density polyethylene resin (LLDPE) as the first resin layer (sealant layer). This was then aged for 4 days at 40°C. This resulted in a gas barrier laminate having a laminate structure of base layer / undercoat layer / inorganic oxide layer / gas barrier adhesive layer / first resin layer (sealant layer).

[0111] [Example 2] A gas barrier laminate was obtained in the same manner as in Example 1, except that the inorganic oxide layer was formed in the following manner: A transparent inorganic oxide layer (alumina vapor deposition film) made of aluminum oxide and having a thickness of 15 nm was formed on the undercoat layer using a vacuum deposition apparatus employing an electron beam heating system.

[0112] [Examples 3 to 4] A gas barrier laminate was obtained in the same manner as in Example 1, except that the thickness of the inorganic oxide layer (silica vapor deposition film) was changed as shown in Table 1.

[0113] [Example 5] A gas barrier laminate was obtained in the same manner as in Example 1, except that adhesive B was used instead of adhesive A.

[0114] [Comparative Example 1] A gas barrier laminate was obtained in the same manner as in Example 1, except that no undercoat layer was formed.

[0115] Comparative Example 2 A gas barrier laminate was obtained in the same manner as in Example 1, except that the inorganic oxide layer was not formed.

[0116] Comparative Example 3 A gas barrier laminate was obtained in the same manner as in Example 1, except that adhesive C was used instead of adhesive A and the thickness of the adhesive layer was set to 2.5 μm. The adhesive layer formed using adhesive C did not have gas barrier properties.

[0117] Comparative Example 4 A gas barrier laminate was obtained in the same manner as in Example 1, except that adhesive D was used instead of adhesive A. The adhesive layer formed using adhesive D did not have gas barrier properties.

[0118] [Example 6] (Formation of Undercoat Layer (Anchor Coat Layer)) In this example, a gas barrier laminate was produced by roll-to-roll technique. First, the above-mentioned composition for forming the undercoat layer was applied by gravure roll coating to the corona-treated surface of a 1-m-wide unstretched high-density polyethylene film (thickness: 32 μm), and then dried and cured at 60°C. The acrylic urethane resin was applied in an amount of 0.1 g / m. 2 An undercoat layer having the formula:

[0119] (Formation of inorganic oxide layer (silica vapor deposition film)) A 30 nm thick transparent inorganic oxide layer (silica vapor deposition film) made of silicon oxide was formed on the undercoat layer using an electron beam heating vacuum deposition apparatus. The vapor deposition material type was adjusted to form a vapor deposition film with an O / Si ratio of 1.8.

[0120] (Preparation of gas barrier laminate) Adhesive A was applied to the inorganic oxide layer by gravure coating and dried at 60°C to form a 3µm thick gas barrier adhesive layer, and then a 60µm thick unstretched film (manufactured by Mitsui Chemicals Tocello, Inc., product name: TUX-MCS) made of linear low-density polyethylene resin (LLDPE) was laminated as the first resin layer (sealant layer). This was then aged for 4 days at 40°C. This resulted in a gas barrier laminate having a laminate structure of base layer / undercoat layer / inorganic oxide layer / gas barrier adhesive layer / first resin layer (sealant layer).

[0121] [Example 7] A gas barrier laminate was obtained in the same manner as in Example 6, except that a stretched high-density polyethylene film (manufactured by Tokyo Ink Co., Ltd., trade name: SMUQ, thickness 25 μm) was used as the base layer.

[0122] [Example 8] A gas barrier laminate was obtained in the same manner as in Example 6, except that an unstretched medium-density polyethylene film (manufactured by Tamapoly Co., Ltd., trade name: UB-3, thickness 40 μm) was used as the base layer.

[0123] [Example 9] A gas barrier laminate was obtained in the same manner as in Example 6, except that a 100 μm thick unstretched film made of linear low-density polyethylene resin (LLDPE) (manufactured by Mitsui Chemicals Tocello, Inc., product name: TUX-MCS) was used as the first resin layer (sealant layer).

[0124] [Example 10] (Formation of Undercoat Layer (Anchor Coat Layer)) In this example, a gas barrier laminate was produced by roll-to-roll technique. First, the above-mentioned composition for forming the undercoat layer was applied by gravure roll coating to the corona-treated surface of a 1 m wide unstretched medium-density polyethylene film (manufactured by Tamapoly Co., Ltd., product name: UB-3, thickness: 40 μm), and then dried and cured at 60°C. The acrylic urethane resin was applied in an amount of 0.1 g / m. 2 An undercoat layer having the formula:

[0125] (Formation of inorganic oxide layer (silica vapor deposition film)) A 30 nm thick transparent inorganic oxide layer (silica vapor deposition film) made of silicon oxide was formed on the undercoat layer using an electron beam heating vacuum deposition apparatus. The vapor deposition material type was adjusted to form a vapor deposition film with an O / Si ratio of 1.8.

[0126] (Preparation of gas barrier laminate) Adhesive A was gravure coated onto the inorganic oxide layer and dried at 60°C to form a 3µm thick gas barrier adhesive layer, followed by laminating a 100µm thick unstretched film (manufactured by Tamapoly Co., Ltd., product name: LK410L) made of linear low-density polyethylene resin (LLDPE) as the first resin layer (sealant layer). This was then aged for 4 days at 40°C. This resulted in a gas barrier laminate having a laminate structure of base layer / undercoat layer / inorganic oxide layer / gas barrier adhesive layer / first resin layer (sealant layer).

[0127] [Example 11] (Formation of Undercoat Layer (Anchor Coat Layer)) In this example, a gas barrier laminate was produced by roll-to-roll technique. First, the above-mentioned composition for forming the undercoat layer was applied by gravure roll coating to the corona-treated surface of a 1-m-wide unstretched high-density polyethylene film (thickness: 32 μm), and then dried and cured at 60°C. The acrylic urethane resin was applied in an amount of 0.1 g / m. 2 An undercoat layer having the formula:

[0128] (Formation of inorganic oxide layer (silica vapor deposition film)) A 30 nm thick transparent inorganic oxide layer (silica vapor deposition film) made of silicon oxide was formed on the undercoat layer using an electron beam heating vacuum deposition apparatus. The vapor deposition material type was adjusted to form a vapor deposition film with an O / Si ratio of 1.8.

[0129] (Formation of printing layer) A pattern was printed by a printing machine on the surface of the substrate layer opposite to the undercoat layer to form a printed layer.

[0130] (Preparation of gas barrier laminate) Adhesive A was gravure coated onto the inorganic oxide layer and dried at 60°C to form a 3µm thick gas barrier adhesive layer, followed by laminating a 100µm thick unstretched film (manufactured by Tamapoly Co., Ltd., product name: LK410L) made of linear low-density polyethylene resin (LLDPE) as the first resin layer (sealant layer). This was then aged at 40°C for 4 days. This resulted in a gas barrier laminate having a laminate structure of print layer / substrate layer / undercoat layer / inorganic oxide layer / gas barrier adhesive layer / first resin layer (sealant layer).

[0131] [Example 12] (Formation of Undercoat Layer (Anchor Coat Layer)) In this example, a gas barrier laminate was produced by roll-to-roll technique. First, the above-mentioned composition for forming the undercoat layer was applied by gravure roll coating to the corona-treated surface of a 1-m-wide unstretched high-density polyethylene film (thickness: 32 μm), and then dried and cured at 60°C. The acrylic urethane resin was applied in an amount of 0.1 g / m. 2 An undercoat layer having the formula:

[0132] (Formation of inorganic oxide layer (silica vapor deposition film)) A 30 nm thick transparent inorganic oxide layer (silica vapor deposition film) made of silicon oxide was formed on the undercoat layer using an electron beam heating vacuum deposition apparatus. The vapor deposition material type was adjusted to form a vapor deposition film with an O / Si ratio of 1.8.

[0133] (Formation of printing layer) A pattern was printed by a printing machine on the corona-treated surface of a stretched high-density polyethylene film (manufactured by Tokyo Ink Co., Ltd., trade name: SMUQ, thickness 25 μm) serving as the first resin layer to form a printed layer.

[0134] (Preparation of gas barrier laminate) Adhesive A was applied to the inorganic oxide layer by gravure coating and dried at 60°C to form a 3µm thick gas barrier adhesive layer, and then the first resin layer with the printed layer formed thereon was laminated with the printed layer facing the gas barrier adhesive layer. Next, the backside of the substrate layer was corona-treated, and Adhesive C was applied by gravure coating and dried at 60°C to form a 3µm thick adhesive layer. A 100µm thick unstretched film (manufactured by Tamapoly Corporation, product name: LK410L) made of linear low-density polyethylene resin (LLDPE) was then laminated as the second resin layer (sealant layer). This resulted in a gas barrier laminate having a laminate structure of second resin layer (sealant layer) / adhesive layer / substrate layer / undercoat layer / inorganic oxide layer / gas barrier adhesive layer / printed layer / first resin layer.

[0135] [Example 13] A gas barrier laminate was obtained in the same manner as in Example 1, except that a biaxially oriented polypropylene film (manufactured by Mitsui Chemicals Tocello Inc., product name: ME-1, thickness 20 μm, OPP film with easy-adhesion coating) was used as the base layer, and a 60 μm thick unstretched polypropylene film (manufactured by Toray Advanced Film Co., Ltd., product name: Torayfan ZK207, CPP film) was used as the first resin layer (sealant layer).

[0136] Comparative Example 5 A gas barrier laminate was obtained in the same manner as in Example 13, except that adhesive C was used instead of adhesive A and the thickness of the adhesive layer was set to 2.5 μm. The adhesive layer formed using adhesive C did not have gas barrier properties.

[0137] [Physical property measurements] (Thermal shrinkage rate) The base material layer was heated at 100°C for 15 minutes, and then the heat shrinkage rates in the machine direction (MD) and the perpendicular direction (TD) were measured. The heat shrinkage rate (%) was calculated using the following formula. Heat shrinkage rate (%) = {(length before heating - length after heating) / length before heating} x 100 The procedure for measuring the heat shrinkage rate is as follows. (1) The substrate layer is cut into a 20 cm x 20 cm sample to be used as a measurement sample. (2) Draw a 10 cm line in the MD or TD direction on the measurement sample (the length before heating). (3) Heat the measurement sample at 100°C for 15 minutes. (4) The length of the written line in the MD or TD direction is measured (length after heating). (5) Calculate the thermal shrinkage rate using the above formula.

[0138] (density) The density of the substrate layer was measured by a measurement method in accordance with JIS K7112:1999.

[0139] (Thermal fusion temperature) The heat fusion temperatures of the substrate layer, the first resin layer, and the second resin layer were measured by measuring the heat sealing temperatures of the measurement target layers using a measurement method in accordance with JIS Z0238: 1998. Specifically, when two measurement target layers were overlapped and heated for one second at a pressure of 0.2 MPa using a heat seal tester to form a heat seal part, the lowest temperature at which a heat seal part that was heat-sealed and did not peel off could be formed was defined as the heat fusion temperature.

[0140] Tables 1 to 3 and 7 also show the difference in heat fusion temperature between the two most distant layers among the three layers of the base material layer, the first resin layer and the second resin layer. The two most distant layers are the first resin layer and the second resin layer in Example 12, and the base material layer and the first resin layer in the other Examples and Comparative Examples.

[0141] (glass transition temperature (Tg)) The Tg (°C) of the undercoat layer, gas barrier adhesive layer, and non-gas barrier adhesive layer was measured using a differential scanning calorimeter using the following method. First, the composition (coating liquid) for forming each layer was placed in a container, and the solvent was removed and the layer was cured at 60°C for one day. Next, the cured product was removed and measured using a differential scanning calorimeter. The initial temperature was set to 0°C, and the layer was held at 0°C for 5 minutes. After that, the layer was heated continuously to 200°C at a rate of 10°C / min. The layer was then cooled and held at 0°C for 5 minutes. The Tg was measured at a peak that appeared under the measurement conditions called the second run, where the layer was heated continuously to 200°C at a rate of 10°C / min.

[0142] Tables 1 to 3 and 7 also show the difference in Tg between the undercoat layer and the gas barrier adhesive layer or non-gas barrier adhesive layer.

[0143] (logarithmic decay rate) Adhesives A to D were applied to 20 μm-thick aluminum foil using a wire bar and dried at 60°C to form a 3 μm-thick coating. This coating was then aged at 50°C for 4 days to prepare a sample. The logarithmic decrement was measured using a rigid pendulum-type physical property tester (manufactured by A&D Co., Ltd., product name: RPT-3000W). The frame (pendulum) used was the RBP-020, with a pipe diameter of 2 mm and a frame weight of 14 g. The measurement width was 20 mm, and the aluminum foil and sample were cut and fixed to a dedicated aluminum plate. The measurement temperature was -80°C to 200°C, and the heating rate was 10°C / min. Under these conditions, the logarithmic decrement was measured at three locations, and the logarithmic decrement data at 30°C was read and the average value was calculated. A small logarithmic decrement indicates that the resin molecules making up the surface of the object being measured are less likely to move when exposed to heat.

[0144] (Oxygen Transmission Rate (OTR)) The oxygen permeability of the gas barrier adhesive layer and the non-gas barrier adhesive layer was measured using the following method. Adhesives A to D were applied to the corona-treated surface of an A4-sized polyethylene (PE) film (32 μm thick) using a wire bar, and then dried and cured at 60°C to form a 3 μm-thick coating film (gas barrier adhesive layer or non-gas barrier adhesive layer). A 60 μm-thick unstretched film made of linear low-density polyethylene resin (LLDPE) (manufactured by Mitsui Chemicals Tohcello, Inc., product name: TUX-MCS) was laminated onto this coating film to obtain a laminate. The oxygen permeability of the resulting laminate was measured at a temperature of 30°C and a relative humidity of 70% (JIS K-7126, Method B). Measurements were performed using an oxygen permeability measuring device (manufactured by MOCON, product name: OX-TRAN2 / 20). The detection limit of this measuring device was 200 cc / m. 2 ·day·atm, so if the measured value is above the detection limit, the oxygen permeability of the adhesive layer is >200cc / m 2 ·day·atm.

[0145] [Evaluation of gas barrier laminate] (Gas barrier properties before and after bending) The gas barrier laminates obtained in the Examples and Comparative Examples were cut into samples measuring 295 mm long x 210 mm wide to prepare evaluation samples. These samples were attached to the fixed head of a Gelbo Flex Tester (product name: BE-1005) manufactured by Tester Sangyo Co., Ltd., so as to form a cylinder with a diameter of 87.5 mm x 210 mm. The sample was held at both ends, with an initial gripping distance of 175 mm, and twisted 440 degrees with a stroke of 87.5 mm. This action was repeated 10 times at a speed of 40 times / min to bend the sample. The oxygen transmission rate (OTR) and water vapor transmission rate (WTR) of the samples were measured before (initial) and after the bending test. The results are shown in Tables 4 to 6 and 8. The oxygen transmission rate and water vapor transmission rate were measured as follows.

[0146] Oxygen permeability: Oxygen permeability measuring device (manufactured by MOCON, product name: OX-TRAN2 / 20) Measured at a temperature of 30°C and a relative humidity of 70% (JIS K-7126, Method B) Measurements are in units of [cc / m 2 Expressed as [day·atm].

[0147] Water vapor transmission rate: Water vapor permeability measuring device (MOCON, product name: PERMATRAN-W 3 / 33) Measured at a temperature of 40°C and a relative humidity of 90% (JIS K-7126, Method B) Measurements are in units of [g / m 2 ·day].

[0148] (Gas barrier properties after boiling treatment) The gas barrier laminates obtained in Examples 5 to 8 were cut into pieces measuring 15 cm x 10 cm. Two of the cut gas barrier laminates (packaging films) were stacked with their sealant layers facing each other and impulse-sealed on three sides to form a pouch. 200 ml of tap water was poured into the pouch, and the remaining edge was impulse-sealed to produce a four-sided sealed pouch (packaging bag). The resulting pouches were subjected to a boiling treatment at 80°C for 30 minutes or 95°C for 30 minutes using a boiling treatment device. After boiling, the pouches were opened, the tap water discarded, and the pouches were thoroughly dried. The oxygen transmission rate (OTR) and water vapor transmission rate (WTR) were measured using the same method as above. The results are shown in Table 5. After boiling, the appearance of the pouches was visually inspected for film delamination or lifting, but no problems were found in any of the pouches.

[0149] (Standing pouch production) Using the gas barrier laminates obtained in Examples 9 to 12, standing pouches measuring 140 mm in width, 210 mm in height, and 35 mm in fold were produced using a pouch-making machine. The appearance of the pouches after production was observed, and no problems were found in any of the pouches. The pouches after production were filled with 100 g of liquid dishwashing detergent (manufactured by Lion Corporation, product name: Charmy Magica) as the contents, and stored at 40°C and 90% RH for one month. After storage, the pouches were opened, the detergent inside the pouches was discarded, washed with tap water, and thoroughly dried. The oxygen transmission rate (OTR) and water vapor transmission rate (WTR) were measured in the same manner as above. The results are shown in Table 6.

[0150] (Gas barrier properties after retort processing) The gas barrier laminates obtained in Example 13 and Comparative Example 5 were cut into pieces measuring 15 cm x 20 cm. The cut gas barrier laminates (packaging films) were folded at the center in the longitudinal direction so that the sealant layers faced each other, and then two-sided impulse sealed into pouches. 200 ml of tap water was placed inside the pouch as the contents, and the remaining edge was impulse sealed to produce three-sided sealed pouches (packaging bags). The resulting pouches were subjected to retort treatment at 0.2 MPa and 121°C for 30 minutes or 0.27 MPa and 130°C for 30 minutes (high retort treatment) in a retort apparatus. After retort treatment, the pouches were opened, the tap water discarded, and thoroughly dried. The oxygen transmission rate (OTR) and water vapor transmission rate (WTR) were measured in the same manner as above. The results are shown in Table 8. After the retort treatment, the appearance of the pouches was visually inspected for any delamination or lifting of the film, but no problems were found in any of the pouches.

[0151] [Table 1]

[0152] [Table 2]

[0153] [Table 3]

[0154] [Table 4]

[0155] [Table 5]

[0156] [Table 6]

[0157] [Table 7]

[0158] [Table 8] [Industrial Applicability]

[0159] The gas barrier laminate according to the present disclosure can maintain high gas barrier properties even after bending, and its constituent films can be substantially all polyolefin films. Such a gas barrier laminate can be said to be a packaging material made of a single material (mono-material), and is expected to have excellent recyclability. [Explanation of symbols]

[0160] 1...base material layer, 2...undercoat layer, 3...inorganic oxide layer, 4...gas barrier adhesive layer, 5...resin layer (first resin layer), 6...printed layer, 7...second resin layer, 8...adhesive layer, 10, 20, 30, 40, 50...gas barrier laminate, 100...packaging bag with stopper, 104...stopper, 105...straw, 140...packaging bag, 500...tube container, 510...body portion, 520...pouring outlet portion, 530...cap.

Claims

1. a substrate layer containing a polyolefin, an undercoat layer, an inorganic oxide layer, a gas barrier adhesive layer, and a resin layer containing a polyolefin laminated in this order; the polyolefin contained in the base layer is polyethylene, the undercoat layer is a layer formed using an anchor coating agent containing an acrylic urethane resin or a component that reacts to form an acrylic urethane resin, the gas barrier adhesive layer is a layer formed using an epoxy adhesive, The gas barrier laminate, wherein the gas barrier adhesive layer has an oxygen permeability of 100 cc / m 2 ·day·atm or less.

2. 2. The gas barrier laminate according to claim 1, wherein the thickness of the gas barrier adhesive layer is 50 times or more the thickness of the inorganic oxide layer.

3. 3. The gas barrier laminate according to claim 1, wherein the surface of the gas barrier adhesive layer has a logarithmic decrement at 30°C of 0.1 or less as measured using a rigid pendulum physical property tester.

4. The gas barrier laminate according to any one of claims 1 to 3, wherein the inorganic oxide layer contains silicon oxide.

5. the resin layer is a sealant layer, 5. The gas barrier laminate according to claim 1, wherein the difference in heat fusion temperature between the base layer and the sealant layer is 10° C. or more.

6. 6. The gas barrier laminate according to claim 1, wherein the difference in Tg between the undercoat layer and the gas barrier adhesive layer is 100° C. or less.

7. The gas barrier laminate according to any one of claims 1 to 6, further comprising a printed layer laminated thereon.

8. The density of the substrate layer is 0.950 g / cm ３ The gas barrier laminate according to any one of claims 1 to 7.

9. 9. The gas barrier laminate according to claim 1, wherein the resin layer is a first resin layer, and a second resin layer containing a polyolefin is further laminated separately from the first resin layer.

10. 10. The gas barrier laminate according to claim 9, wherein the difference in heat fusion temperature between the two most distant layers of the three layers of the base layer, the first resin layer, and the second resin layer is 10°C or more.

11. A packaging bag produced by forming the gas barrier laminate according to any one of claims 1 to 10.

Images