Gas barrier laminates and packaging bags

Abstract

To provide a gas barrier laminate which has a fold retention property that is a feature of paper and has a high water vapor barrier property even after having been bent, and contributes to reduction in a used amount of a plastic material, and a packaging bag containing the same.SOLUTION: A gas barrier laminate has a paper base material, an anchor coat layer containing at least one of a polyvinyl alcohol-based resin and polyolefin having a polar group, a vapor-deposited layer, an adhesive layer, and a sealant layer in this order.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to gas barrier laminates and packaging bags. [Background technology]

[0002] In many fields, including food, beverages, pharmaceuticals, and chemicals, packaging materials are used that are appropriate for the contents. These packaging materials must have gas barrier properties, preventing the permeation of water vapor and other gases that can cause deterioration of the contents.

[0003] In recent years, growing environmental awareness stemming from issues such as marine plastic waste has led to a momentum for reducing plastic use. From the perspective of reducing the amount of plastic materials used, the use of paper as a substitute for plastic materials is being considered in various fields.

[0004] For example, Patent Document 1 discloses a packaging material having a paper substrate layer, a dry laminating adhesive layer, and a specific sealant layer laminated adjacent to the dry laminating adhesive layer. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2012-250486 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Paper has the advantage of being easy to process due to its crease-holding ability (also known as dead-holding ability). However, our research has revealed that when using packaging bags with sharper creases (pillow packaging, three-side seal packaging, and gusset packaging), cracks occur in the layers, reducing the gas barrier properties, and there is still room for improvement.

[0007] Furthermore, from the perspective of the Law for the Promotion of Effective Utilization of Resources, it is required to reduce the amount of plastic material used in gas barrier laminates.

[0008] This disclosure provides a gas barrier laminate that possesses the crease-retaining properties characteristic of paper, maintains high water vapor barrier properties even after being folded, and contributes to reducing the amount of plastic material used, as well as a packaging bag containing the same. [Means for solving the problem]

[0009] A gas barrier laminate according to one aspect of the present invention comprises, in this order, a paper substrate, an anchor coat layer containing at least one of a polyvinyl alcohol-based resin and a polyolefin having polar groups, a vapor deposition layer, an adhesive layer, and a sealant layer.

[0010] The anchor coat layer may contain a polyolefin having the polar group, and the polyolefin having the polar group may have at least one selected from the group consisting of a carboxyl group, a salt of a carboxyl group, a carboxylic acid anhydride, and a carboxylic acid ester.

[0011] The anchor coat layer may contain a polyolefin having the polar group, and the polyolefin having the polar group may be a copolymer of an acrylic acid ester and maleic anhydride.

[0012] The anchor coat layer may contain a polyolefin having the polar group, and the polyolefin having the polar group may be an ethylene-vinyl acetate copolymer.

[0013] The anchor coat layer may contain a polyolefin having the polar group, and the polyolefin having the polar group may be an ethylene-glycidyl methacrylate copolymer.

[0014] The above-mentioned anchor coating layer may also contain the above-mentioned polyvinyl alcohol-based resin.

[0015] The above adhesive layer is a cured product of a resin composition containing an epoxy resin and an epoxy resin curing agent, and the epoxy resin curing agent may be a reaction product of metaxylylenediamine or paraxylylenediamine and an unsaturated carboxylic acid represented by the following formula (1) and / or a derivative thereof.

[0016] [Chemical formula] [In formula (1), R 1 represents an alkyl group having 1 to 8 carbon atoms, an aralkyl group having 1 to 8 carbon atoms, or an aryl group.]

[0017] The above adhesive layer may be a cured product of a resin composition containing a polyol having two or more hydroxyl groups in one molecule and an isocyanate compound having two or more isocyanate groups in one molecule.

[0018] The weight of the above paper base material may be 50% by mass or more based on the entire gas barrier laminate.

[0019] The packaging bag according to another aspect of the present invention includes the above gas barrier laminate.

[0020] The above packaging bag may have a fold. [Advantages of the Invention]

[0021] According to the present disclosure, there are provided a gas barrier laminate having fold retention, which is a characteristic of paper, and having a high water vapor barrier property even after being folded, and contributing to a reduction in the amount of plastic material used, and a packaging bag including the same. [Brief Description of the Drawings]

[0022] [Figure 1] It is a schematic cross-sectional view showing a gas barrier laminate according to an embodiment of the present invention. [Figure 2] It is a perspective view showing a packaging bag according to an embodiment of the present invention. [Modes for carrying out the invention]

[0023] The embodiments of the present invention will be described in detail below, with reference to the drawings as appropriate. However, the present invention is not limited to the following embodiments.

[0024] <Gas barrier laminate> Figure 1 is a schematic cross-sectional view showing a gas barrier laminate according to one embodiment. The gas barrier laminate 10 according to one embodiment comprises, in this order, a paper substrate 1, an anchor coat layer 2, a vapor deposition layer 3, an adhesive layer 4, and a sealant layer 5. The anchor coat layer 2 contains at least one of a polyvinyl alcohol-based resin and a polyolefin having polar groups.

[0025] [Paper base material] The paper substrate 1 is not particularly limited and can be appropriately selected depending on the application of the packaging bag to which the gas barrier laminate 10 is applied. There are no particular restrictions as long as the paper is primarily composed of plant-derived pulp. Specific examples of paper substrate 1 include fine paper, special fine paper, coated paper, art paper, cast coated paper, imitation paper, kraft paper, and glassine paper. The thickness of the paper substrate 1 can be, for example, 20 to 500 g / m². 2 , or 30-100g / m 2 That's fine.

[0026] The paper substrate 1 may have a coating layer on at least the side in contact with the anchor coating layer 2, which will be described later. By providing a coating layer, it is possible to prevent the anchor coating layer from seeping into the paper, and it can also act as a sealer to fill in the irregularities of the paper, allowing the anchor coating layer to be formed uniformly without defects. As a result, the gas barrier laminate 10 has even better gas barrier properties. The coating layer may include, for example, various copolymers such as styrene-butadiene, styrene-acrylic, and ethylene-vinyl acetate, polyvinyl alcohol resins, cellulose resins, paraffin (wax), etc., as binder resins, and may contain clay, kaolin, calcium carbonate, talc, mica, etc., as fillers.

[0027] The thickness of the coating layer is not particularly limited, but may be, for example, 1 to 10 μm or 3 to 8 μm.

[0028] The weight of the paper substrate is preferably 50% or more by mass of the entire gas barrier laminate, more preferably 70% or more by mass, and even more preferably 80% or more by mass. If the weight of the paper is 50% or more by mass of the entire gas barrier laminate, the amount of plastic material used can be sufficiently reduced, the entire gas barrier laminate can be said to be made of paper, and it has excellent recyclability.

[0029] [Anchor coat layer] The anchor coat layer 2 is provided on the surface of the paper substrate 1 to improve adhesion between the paper substrate 1 and the vapor-deposited layer 3 (described later), and to improve the gas barrier properties of the gas barrier laminate. The anchor coat layer 2 contains at least one of a polyvinyl alcohol-based resin and a polyolefin having polar groups. As a result, the gas barrier laminate 10 has excellent gas barrier properties (particularly water vapor barrier properties). It is preferable that the anchor coat layer 2 contains a polyvinyl alcohol-based resin because it further improves water vapor barrier properties and oxygen barrier properties.

[0030] The anchor coat layer 2 contains a polyolefin with polar groups, which enables the formation of a dense film due to the crystalline nature of the polyolefin, resulting in water vapor barrier properties. The crystalline nature of the polyolefin provides water vapor barrier properties, and the presence of polar groups ensures adhesion with the vapor-deposited layer 3.

[0031] A polyolefin having a polar group may have at least one selected from a carboxyl group, a salt of a carboxyl group, a carboxylic acid anhydride, and a carboxylic acid ester.

[0032] As the polyolefin having polar groups, copolymers of ethylene or propylene with unsaturated carboxylic acids (unsaturated compounds having carboxyl groups such as acrylic acid, methacrylic acid, and maleic anhydride), unsaturated carboxylic acid esters, and salts obtained by neutralizing carboxylic acids with basic compounds may be used. In addition, copolymers with vinyl acetate, epoxy compounds, chlorine compounds, urethane compounds, polyamide compounds, etc., may also be used.

[0033] Examples of polyolefins having polar groups include copolymers of acrylic acid esters and maleic anhydride, ethylene-vinyl acetate copolymers, and ethylene-glycidyl methacrylate copolymers.

[0034] Polyvinyl alcohol-based resins include, for example, fully saponified polyvinyl alcohol resins, partially saponified polyvinyl alcohol resins, modified polyvinyl alcohol resins, and ethylene-vinyl alcohol copolymer resins. The degree of polymerization of the polyvinyl alcohol-based resin is preferably 300 or higher and 1700 or lower. If the degree of polymerization is 300 or higher, the gas barrier properties and flexural resistance of the gas barrier laminate will be good, and if the degree of polymerization is 1700 or lower, the viscosity of the polyvinyl alcohol-based resin coating solution, described later, will be low, resulting in good coatability.

[0035] When the anchor coat layer 2 contains a polyvinyl alcohol-based resin, it offers excellent flexibility, suppresses cracking of the vapor-deposited layer (described later) after bending (folding), reduces deterioration of gas barrier properties, and improves adhesion between the vapor-deposited layer and the anchor coat layer 2.

[0036] The anchor coat layer 2 may contain other components in addition to the polyolefin and polyvinyl alcohol-based resins mentioned above. Examples of other components include resins such as polyolefins other than the polyolefins mentioned above, polyacrylics, polyesters, polyurethanes, polyethyleneimines, polylactic acid, polyamides, starches and their derivatives, and cellulose derivatives, as well as additives such as silane coupling agents, organic titanates, glycerin, glycols, casein, and waxes.

[0037] The total content of polyolefin and polyvinyl alcohol-based resin in the anchor coat layer 2 may be, for example, 50% by mass or more, 70% by mass or more, 90% by mass or more, or 100% by mass.

[0038] The thickness of the anchor coat layer 2 may be, for example, 1 μm or more, 2 μm or more, 20 μm or less, 10 μm or less, or 5 μm or less. If the thickness of the anchor coat layer 2 is 1 μm or more, the irregularities of the paper substrate 1 described above can be efficiently filled, and the vapor-deposited layer 3 described later can be uniformly laminated. Also, if the thickness of the anchor coat layer 2 is 20 μm or less, the vapor-deposited layer 3 can be uniformly laminated while keeping costs down.

[0039] Examples of solvents included in the coating solution for the anchor coat layer 2 include water, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, n-pentyl alcohol, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, toluene, hexane, heptane, cyclohexane, acetone, methyl ethyl ketone, diethyl ether, dioxane, tetrahydrofuran, ethyl acetate, and butyl acetate. These solvents may be used individually or in combination of two or more. Among these, methyl alcohol, ethyl alcohol, isopropyl alcohol, toluene, ethyl acetate, methyl ethyl ketone, and water are preferred from the viewpoint of properties. Furthermore, methyl alcohol, ethyl alcohol, isopropyl alcohol, and water are preferred from the viewpoint of environmental impact.

[0040] The anchor coat layer 2 can be obtained by applying a coating solution containing at least one of the above-mentioned polyolefin and polyvinyl alcohol-based resin and a solvent onto a paper substrate and drying it. From the viewpoint of preventing blocking, the particle size of the polyolefin in the coating solution should be large so that the contact area is small. Although not particularly limited, the particle size may be 1 nm or larger, 0.1 μm or larger, 1 μm or less, 0.7 μm or less, or 0.5 μm or less.

[0041] [Vapour-deposited layer] The vapor-deposited layer 3 is a layer on which a metal or inorganic compound has been deposited. The vapor-deposited layer may be one obtained by depositing aluminum, or aluminum oxide (AlO x ), silicon dioxide (SiO₂) x ) and other similar items may also be included.

[0042] The thickness of the vapor-deposited layer 3 can be set appropriately depending on the application, but is preferably 10 nm or more, 30 nm or more, or 50 nm or more, and may be 300 nm or less, 100 nm or less, or 80 nm or less. Setting the thickness of the vapor-deposited layer 3 to 10 nm or more makes it easier to ensure sufficient continuity of the vapor-deposited layer 3, and setting it to 300 nm or less makes it easier to suppress the occurrence of curl and cracks, thereby easily achieving sufficient gas barrier performance and flexibility.

[0043] The deposited layer 3 is preferably deposited by a vacuum deposition method from the viewpoint of oxygen gas barrier performance and film uniformity. Known deposition methods include vacuum deposition, sputtering, and chemical vapor deposition (CVD), but vacuum deposition is preferred because it has a fast deposition rate and high productivity. Among vacuum deposition methods, electron beam heating is particularly effective because the deposition rate can be easily controlled by the irradiation area and electron beam current, and the heating and cooling of the deposition material can be performed in a short time.

[0044] [Adhesive layer] The adhesive layer 4 is provided on the surface of the vapor-deposited layer 3, in contact with the vapor-deposited layer 3. Various materials can be used as the adhesive layer 4, as long as they adhere the vapor-deposited layer 3 and the sealant layer 5 tightly together. Examples include cured urethane adhesives and cured epoxy adhesives.

[0045] <Urethane-based adhesive> The urethane adhesive is a resin composition containing a polyol having two or more hydroxyl groups in one molecule and an isocyanate compound having two or more isocyanate groups in one molecule. Urethane bonds are formed when the urethane adhesive is cured. The urethane adhesive is preferably a two-component curing type.

[0046] Urethane adhesives may have gas barrier properties. Methods for imparting gas barrier properties to urethane adhesives include, for example, using a polyol having a gas barrier skeleton, incorporating a phosphate-modified compound into the resin composition, or incorporating a plate-like inorganic compound into the resin composition. These methods can be used individually or in combination of two or more methods.

[0047] As a polyol having a barrier-type skeleton, it is preferable that the main skeleton is polyester or polyester polyurethane, and the polyester contains a structure derived from an ortho-oriented aromatic dicarboxylic acid or its anhydride. The polyester portion of the main skeleton may be obtained by polycondensation reaction of a polycarboxylic acid and a polyhydric alcohol.

[0048] Examples of polycarboxylic acids include aliphatic polycarboxylic acids and aromatic polycarboxylic acids. Examples of aliphatic polycarboxylic acids include succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid.

[0049] Examples of aromatic polycarboxylic acids include orthophthalic acid, terephthalic acid, isophthalic acid, pyromellitic acid, trimellitic acid, 1,2-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid and the anhydrides of these dicarboxylic acids, as well as polybasic acids such as p-hydroxybenzoic acid and p-(2-hydroxyethoxy)benzoic acid. Polycarboxylic acids can be used individually or in combination of two or more.

[0050] As the polycarboxylic acid, ortho-oriented aromatic dicarboxylic acid or its anhydride is preferred. The content of ortho-oriented aromatic dicarboxylic acid or its anhydride is preferably 70 to 100% by mass, based on the total amount of polycarboxylic acid components constituting the polyester.

[0051] Examples of ortho-oriented aromatic dicarboxylic acids include orthophthalic acid, 1,2-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, and the anhydrides of these dicarboxylic acids.

[0052] Examples of polyhydric alcohols include aliphatic polyhydric alcohols and aromatic polyhydric phenols. Examples of aliphatic polyhydric alcohols include ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, cyclohexanedimethanol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, methylpentanediol, dimethylbutanediol, butylethylpropanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol.

[0053] Examples of aromatic polyhydric phenols include hydroquinone, resorcinol, catechol, naphthalenediol, biphenol, bisphenol A, hisphenol F, and tetramethylbiphenol, as well as their ethylene oxide extensions and hydrogenated alicyclic compounds.

[0054] The isocyanate compound may be aromatic with an aromatic ring, or aliphatic without an aromatic ring, and may be a low molecular weight compound or a high molecular weight compound, and may be a diisocyanate compound with two isocyanate groups or a polyisocyanate compound with three or more isocyanate groups. The isocyanate compound may also be a blocked isocyanate compound obtained by an addition reaction with an isocyanate blocking agent.

[0055] From the viewpoint of adhesion of the adhesive layer 4, polyisocyanate compounds are preferred as isocyanate compounds. Since the isocyanate compound imparts oxygen barrier properties to the adhesive layer 4, those having an aromatic ring are preferred, and isocyanate compounds containing a metaxylene skeleton are particularly preferred.

[0056] Examples of isocyanate compounds include tetramethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, metaxylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, and trimers of these isocyanate compounds. These isocyanate compounds may be adducts, burettes, or allophanates obtained by reacting isocyanate compounds with low molecular weight active hydrogen compounds such as ethylene glycol, propylene glycol, metaxylylene alcohol, 1,3-bishydroxyethylbenzene, 1,4-bishydroxyethylbenzene, trimethylolpropane, glycerol, pentaerythritol, erythritol, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, metaxylylenediamine, and their alkylene oxide adducts, as well as high molecular weight active hydrogen compounds such as various polyester resins, polyether polyols, and polyamides.

[0057] <Epoxy adhesive> Epoxy adhesives are resin compositions containing epoxy resin and an epoxy resin curing agent.

[0058] The epoxy resin may have saturated or unsaturated bonds, and may be an aliphatic compound, alicyclic compound, aromatic compound, or heterocyclic compound. To exhibit higher gas barrier properties, epoxy resins containing aromatic rings or alicyclic structures within the molecule are preferred.

[0059] Examples of epoxy resins include epoxy resins having glycidylamino groups derived from metaxylylenediamine, epoxy resins having glycidylamino groups derived from 1,3-bis(aminomethyl)cyclohexane, epoxy resins having glycidylamino groups derived from diaminodiphenylmethane, epoxy resins having glycidylamino groups and / or glycidyloxy groups derived from para-aminophenol, epoxy resins having glycidyloxy groups derived from bisphenol A, epoxy resins having glycidyloxy groups derived from bisphenol F, epoxy resins having glycidyloxy groups derived from phenol novolac, and epoxy resins having glycidyloxy groups derived from resorcinol. Epoxy resins may be used individually or in combination of two or more. From the viewpoint of gas barrier properties, epoxy resins having glycidylamino groups derived from metaxylylenediamine and epoxy resins having glycidyloxy groups derived from bisphenol F are preferred, and epoxy resins having glycidylamino groups derived from metaxylylenediamine are more preferred.

[0060] The epoxy resin curing agent may be a reaction product of metaxylylenediamine or paraxylylenediamine and an unsaturated carboxylic acid and / or its derivative represented by the following formula (1).

[0061] [ka] [In formula (1), R 1 This represents an alkyl group having 1 to 8 carbon atoms, an aralkyl group having 1 to 8 carbon atoms, or an aryl group.

[0062] By using metaxylylenediamine or paraxylylenediamine as a precursor for the epoxy resin curing agent, the gas barrier properties are further improved. From the viewpoint of gas barrier properties, metaxylylenediamine is preferred over paraxylylenediamine. Metaxylylenediamine or paraxylylenediamine may be used individually or in combination of two or more.

[0063] By using the unsaturated carboxylic acid represented by formula (1) and / or its derivatives as a precursor for the epoxy resin curing agent, good adhesion is achieved. Examples of the unsaturated carboxylic acid represented by formula (1) and / or its derivatives include, but are not limited to, unsaturated carboxylic acids such as crotonic acid, 2-pentenoic acid, 2-hexenoic acid, 4-methyl-2-pentenoic acid, 2-heptenoic acid, 4-methyl-2-hexenoic acid, 5-methyl-2-hexenoic acid, 4,4-dimethyl-2-pentenoic acid, 4-phenyl-2-butenoic acid, cinnamic acid, o-methylcinnamic acid, m-methylcinnamic acid, p-methylcinnamic acid, 2-octenoic acid, 2-nonenic acid, 2-decenoic acid, and 2-undecenoic acid, and their derivatives (e.g., esters, amides, acid anhydrides, acid chlorides, etc.). The unsaturated carboxylic acid represented by formula (1) and / or its derivatives may be used individually or in combination of two or more.

[0064] The unsaturated carboxylic acid and / or derivative thereof represented by formula (1) above is used to further improve gas barrier properties and adhesion, and R in formula (1) above 1 Preferably, at least one selected from the group consisting of unsaturated carboxylic acids and their derivatives, in which the group has 1 to 3 hydrocarbon groups or phenyl groups, more preferably at least one selected from the group consisting of crotonic acid and crotonic acid derivatives, and even more preferably at least one selected from the group consisting of crotonic acid and crotonic acid esters. As for crotonic acid esters, alkyl esters having 1 to 3 carbon atoms are more preferred, and methyl crotonic acid is even more preferred.

[0065] The adhesive layer 4 may be formed using a one-component curing type or a two-component curing type adhesive (dry lamination method), a solvent-free adhesive (non-solvent dry lamination method), or by extruding molten resin onto the surface of the vapor-deposited layer 3 (extrusion lamination method).

[0066] The thickness of the adhesive layer 4 is preferably 0.01 μm or more from the viewpoint of improving the adhesion of the adhesive layer 4, and preferably 10 μm or less from the viewpoint of further reducing the amount of plastic material used.

[0067] [Sealant layer] The sealant layer 5 is provided on the surface of the adhesive layer 4, in contact with the adhesive layer 4. Examples of materials for the sealant layer 5 include thermoplastic resins such as polyolefin resin and polyester resin, but polyolefin resin is generally used. Specifically, as polyolefin resins, ethylene-based 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, polypropylene-based resins such as homopolypropylene resin (PP), propylene-ethylene random copolymer, propylene-ethylene block copolymer, and propylene-α-olefin copolymer, or mixtures thereof can be used.

[0068] The thickness of the sealant layer is preferably 5 μm or more, as this improves the seal strength, and preferably 50 μm or less, as this further reduces the amount of plastic material used.

[0069] Although embodiments of the present disclosure have been described in detail above, the present invention is not limited to the above embodiments. For example, in the gas barrier laminate 10, a coating layer may be provided between the vapor-deposited layer 3 and the adhesive layer 4 as a layer for protecting the vapor-deposited layer 3. Examples of materials for such a coating layer include polyvinyl alcohol-based resins, polyolefin-based resins, polyester-based resins, polyurethane-based resins, and epoxy-amine-based resins.

[0070] <Packaging bag> Figure 2 is a perspective view showing a gusset bag 20 made of a gas barrier laminate 10. The packaging bag is manufactured by sealing the opening at the top of the gusset bag 20. The gusset bag 20 has folded sections (folded sections B1, B2) where the gas barrier laminate 10 is folded. Folded section B1 is where the gas barrier laminate 10 is valley-folded when viewed from the innermost layer side, while folded section B2 is where the gas barrier laminate 10 is mountain-folded when viewed from the innermost layer side.

[0071] The packaging bag may be formed by folding a single gas barrier laminate in half so that the sealant layers 5 face each other, then folding it appropriately to the desired shape and heat-sealing it, or by stacking two gas barrier laminates so that the sealant layers 5 face each other and then heat-sealing them to form a bag.

[0072] In the packaging bag according to this embodiment, the heat seal strength may be 2N or more, and may be 10N or more. There is no particular upper limit to the heat seal strength, but it may be, for example, 20N or less.

[0073] The packaging bag can contain contents such as food and pharmaceuticals. It is particularly suitable for containing confectionery and similar items. The packaging bag according to this embodiment can maintain high gas barrier properties even when it has a folded portion.

[0074] In this embodiment, a gusseted bag was given as an example of a packaging bag, but the gas barrier laminate according to this embodiment may also be used to produce, for example, pillow bags, three-sided sealed bags, or standing pouches. [Examples]

[0075] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0076] <Fabrication of gas barrier laminates> (Example 1) Paper (clay-coated paper, paper thickness: 50 μm, clay coating layer thickness: 5 μm, basis weight: 55 g / m²) 2 A coating solution containing a carboxyl group salt (product name: Chemipearl S100, ionomer type, particle size: <0.1 μm, solvent: water, IPA, manufactured by Mitsui Chemicals) was applied to the surface of the paper using a bar coater and dried in an oven to form an anchor coat layer (thickness: 3 μm). An AL vapor deposition layer (thickness: 50 nm) was formed on the anchor coat layer by AL vapor deposition. A linear low-density polyethylene resin (LLDPE) film (product name: TUX-MCS, manufactured by Mitsui Chemicals Tohcello Co., Ltd., thickness: 30 μm) as a sealant layer was dry laminated onto the vapor deposition layer using an adhesive (product name: Takelac A525 / Takenate A52, urethane-based two-component type, manufactured by Mitsui Chemicals, Inc.) to obtain a gas barrier laminate. The thickness of the adhesive layer was 5 μm. The weight of paper in the gas barrier laminate was 53 mass%.

[0077] (Example 2) A polyolefin aqueous dispersion was prepared by neutralizing Bondine HX-8290 (trade name, manufactured by Arkema), a copolymer of acrylic acid ester and maleic anhydride, with triethylamine in a water / IPA mixed solvent. Note that maleic anhydride undergoes partial or complete ring-opening in the aqueous solvent to form a carboxylic acid, but after drying, it undergoes partial or complete dehydration and cyclization again. A gas barrier laminate was obtained in the same manner as in Example 1, except that the anchor coat layer was formed using the polyolefin aqueous dispersion instead of a coating solution containing a carboxyl group salt. The weight of paper in the gas barrier laminate was 53% by mass.

[0078] (Example 3) A gas barrier laminate was obtained in the same manner as in Example 1, except that an ethylene-glycidyl methacrylate copolymer (product name: Sepolsion G515, manufactured by Sumitomo Seika) was used to form the anchor coat layer instead of a coating solution containing a carboxyl group salt. The weight of paper in the gas barrier laminate was 53% by mass.

[0079] (Example 4) A gas barrier laminate was obtained in the same manner as in Example 1, except that the anchor coat layer was formed using a coating solution made of ethylene-vinyl acetate copolymer (product name: Chemipearl V300, manufactured by Mitsui Chemicals, Inc.) instead of a coating solution containing a carboxyl group salt. The weight of paper in the gas barrier laminate was 53% by mass.

[0080] (Example 5) A gas barrier laminate was obtained in the same manner as in Example 1, except that silica was used instead of aluminum in the vapor-deposited layer. The weight of paper in the gas barrier laminate was 53% by mass.

[0081] (Example 6) A gas barrier laminate was obtained in the same manner as in Example 1, except that the adhesive layer was formed using Maxive M-100 / C-93 (trade name, manufactured by Mitsubishi Gas Chemical Company, Inc., an epoxy adhesive with gas barrier properties) instead of Takelac A525 / Takenate A52. The weight of paper in the gas barrier laminate was 53% by mass.

[0082] (Example 7) A gas barrier laminate was obtained in the same manner as in Example 1, except that the adhesive layer was formed using PASLIM VM001 / 108CP (product name, manufactured by DIC Corporation, a urethane-based adhesive with gas barrier properties) instead of Takelac A525 / Takenate A52. The weight of paper in the gas barrier laminate was 53% by mass.

[0083] (Example 8) An anchor coat layer was formed on the surface of the paper, and an AL vapor-deposited layer was formed on the anchor coat layer, in the same manner as in Example 1. A linear low-density polyethylene resin (LLDPE) film (product name: TUX-MCS, manufactured by Mitsui Chemicals Tohcello Co., Ltd., thickness: 30 μm) as a sealant layer was laminated onto the vapor-deposited layer using NSRD011 / NSRD006 (product name, manufactured by DIC Corporation, a solvent-free adhesive with gas barrier properties) in a non-solvent dry lamination manner to obtain a gas barrier laminate. The thickness of the adhesive layer was 5 μm. The weight of the paper in the gas barrier laminate was 53% by mass.

[0084] (Example 9) An anchor coat layer was formed on the surface of the paper, and an AL vapor-deposited layer was formed on the anchor coat layer, in the same manner as in Example 1. A-3210 / A-3075 (trade name, manufactured by Mitsui Chemicals, Inc.) was extruded onto the vapor-deposited layer, and the vapor-deposited layer and a low-density polyethylene resin (LDPE) film (trade name: Novatic LC-600A, manufactured by Nippon Polyethylene Co., Ltd.) as a sealant layer were laminated via A-3210 / A-3075 to obtain a gas barrier laminate. The thickness of the adhesive layer was 5 μm. The weight of the paper in the gas barrier laminate was 57% by mass.

[0085] (Example 10) A gas barrier laminate was obtained in the same manner as in Example 1, except that a polyvinyl alcohol-based resin (saponification degree: 98%, polymerization degree: 500) was used to form the anchor coat layer instead of a coating solution containing a carboxyl group salt. The weight of paper in the gas barrier laminate was 53% by mass.

[0086] (Example 11) A gas barrier laminate was obtained in the same manner as in Example 1, except that a polyvinyl alcohol-based resin (saponification degree: 88%, polymerization degree: 500) was used to form the anchor coat layer instead of a coating solution containing a carboxyl group salt. The weight of paper in the gas barrier laminate was 53% by mass.

[0087] (Example 12) A gas barrier laminate was obtained in the same manner as in Example 1, except that the anchor coat layer was formed using a modified polyvinyl alcohol-based resin (product name: Exceval AQ4104, manufactured by Kuraray Co., Ltd.) instead of a coating solution containing a carboxyl group salt. The weight of paper in the gas barrier laminate was 53% by mass.

[0088] (Example 13) A gas barrier laminate was obtained in the same manner as in Example 10, except that silica was used instead of aluminum in the vapor-deposited layer. The weight of paper in the gas barrier laminate was 53% by mass.

[0089] (Example 14) A gas barrier laminate was obtained in the same manner as in Example 10, except that the adhesive layer was formed using EA-N370A / B (product name, manufactured by Toyo Ink Co., Ltd.) instead of Takelac A525 / Takenate A52. The weight of paper in the gas barrier laminate was 53% by mass.

[0090] (Example 15) An anchor coat layer was formed on the surface of the paper, and an AL vapor-deposited layer was formed on the anchor coat layer, in the same manner as in Example 10. A-3210 / A-3075 (trade name, manufactured by Mitsui Chemicals, Inc.) was extruded onto the vapor-deposited layer, and the vapor-deposited layer and a low-density polyethylene resin (LDPE) film (trade name: Novatic LC-600A, manufactured by Nippon Polyethylene Co., Ltd.) as a sealant layer were laminated via A-3210 / A-3075 to obtain a gas barrier laminate. The thickness of the adhesive layer was 0.2 μm. The weight of the paper in the gas barrier laminate was 57% by mass.

[0091] (Comparative Example 1) The anchor coat layer was made of a urethane-cured acrylic resin which is a cured product of an acrylic polyol (an acrylic polyol is a polymer of an acrylic acid derivative monomer or a polymer of an acrylic acid derivative monomer and other monomers and has a hydroxyl group at the terminal), the thickness of the adhesive layer was 0.2 μm, and a gas barrier laminate was obtained by the same operation as in Example 1 except that a low-density polyethylene resin (LDPE) film (product name: Novatic LC-600A, manufactured by Nippon Polyethylene Co., Ltd.) was used as the sealant layer. The weight of the paper in the gas barrier laminate was 57% by mass.

[0092] (Comparative Example 2) A gas barrier laminate was obtained in the same manner as in Comparative Example 1 except that the thickness of the anchor coat layer was 1 μm. The weight of the paper in the gas barrier laminate was 57% by mass.

[0093] <Measurement of water vapor permeability> The water vapor permeability of the gas barrier laminates according to the examples and comparative examples was measured by the MOCON method. The measurement conditions were a temperature of 40°C and a relative humidity of 90%. While rolling a 600 g roller at a speed of 300 mm / min, a fold was made on the gas barrier laminate, and the water vapor permeability of the gas barrier laminate after opening was also measured in the same manner. "Outer fold" in Tables 1 to 4 indicates the gas barrier laminate after valley-folding the gas barrier laminate as viewed from the paper substrate side. The results in Tables 1 to 4 are expressed in the unit [g / m 2 ·day].

[0094] <Measurement of oxygen permeability> The oxygen permeability of the gas barrier laminates according to the examples and comparative examples was measured by the JIS K7126, Method B (isobaric method). The measuring device used was OXTRAN 2 / 20 manufactured by MOCON, and the measurement was carried out at a temperature of 30°C and a relative humidity of 70%. The results in Tables 1 to 4 are shown in the unit [cc / m 2 / d / atm].

[0095] <Measurement of heat seal strength> Two gas barrier laminates were stacked with the sealant layers facing each other, and heat-sealed using a heat sealer at 120°C, 0.2 MPa, and 1 second. The resulting strips were then cut into 15 mm wide strips, and the maximum load was measured when peeled in a T-shape at a peeling speed of 300 mm / min. The results are shown in Tables 1-4 in units of [N / 15 mm].

[0096] [Table 1]

[0097] [Table 2]

[0098] [Table 3]

[0099] [Table 4] [Explanation of Symbols]

[0100] 1...Paper substrate, 2...Anchor coat layer, 3...Vaporized layer, 4...Adhesive layer, 5...Sealant layer, 10...Gas barrier laminate, 20...Gusseted bag, B1, B2...Folded section.

Claims

1. Paper substrate and An anchor coat layer comprising at least one of a polyvinyl alcohol-based resin and a polyolefin having polar groups, A vapor-deposited layer and Adhesive layer, The sealant layer, These are provided in this order, The anchor coat layer and the adhesive layer are in contact with the vapor-deposited layer, respectively. The adhesive layer is a cured product of a urethane-based adhesive or a cured product of an epoxy-based adhesive. The urethane adhesive is a resin composition comprising a polyol having two or more hydroxyl groups in one molecule and an isocyanate compound having two or more isocyanate groups in one molecule. The epoxy adhesive is a resin composition comprising an epoxy resin and an epoxy resin curing agent. A gas barrier laminate in which the epoxy resin curing agent is a reaction product of metaxylylenediamine or paraxylylenediamine and an unsaturated carboxylic acid and / or its derivative represented by the following formula (1). 【Chemistry 1】 [In formula (1), R1 represents an alkyl group having 1 to 8 carbon atoms, an aralkyl group having 1 to 8 carbon atoms, or an aryl group.]

2. The anchor coat layer comprises a polyolefin having the polar group, The gas barrier laminate according to claim 1, wherein the polyolefin having the polar group comprises at least one selected from the group consisting of a carboxyl group, a salt of a carboxyl group, a carboxylic acid anhydride, and a carboxylic acid ester.

3. The anchor coat layer comprises a polyolefin having the polar group, The gas barrier laminate according to claim 1, wherein the polyolefin having the polar group is a copolymer of an acrylic acid ester and maleic anhydride.

4. The anchor coat layer comprises a polyolefin having the polar group, The gas barrier laminate according to claim 1, wherein the polyolefin having the polar group is an ethylene-vinyl acetate copolymer.

5. The anchor coat layer comprises a polyolefin having the polar group, The gas barrier laminate according to claim 1, wherein the polyolefin having the polar group is an ethylene-glycidyl methacrylate copolymer.

6. The gas barrier laminate according to claim 1, wherein the anchor coat layer contains the polyvinyl alcohol-based resin.

7. The gas barrier laminate according to any one of claims 1 to 6, wherein the weight of the paper substrate is 50% by mass or more based on the entire gas barrier laminate.

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

9. A packaging bag according to claim 8, having a foldable portion.

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