Barrier laminate and packaging bag

Abstract

The present invention provides a barrier multilayer body which has good barrier properties and forms a packaging bag that has excellent visibility of the content. A barrier multilayer body which sequentially comprises, on at least one surface of a paper base material, an anchor coat layer and a water vapor barrier layer in this order, wherein: the total light transmittance as determined in accordance with JIS K 7361-1 (1997) is 65% or more; and the arithmetic mean height of the water vapor barrier layer-side surface as determined in accordance with JIS B 0601 (2001) is 75 μm or less.

Description

[Technical Field]

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

[0002] Packaging materials in which water vapor barrier properties or gas barrier properties, particularly oxygen barrier properties, have been imparted to a paper substrate have conventionally been used in packaging foods, medical products, electronic components, and the like to prevent deterioration of the contents.

[0003] A common method for imparting water vapor barrier properties and gas barrier properties to a paper substrate is to laminate a synthetic resin film with excellent gas barrier properties onto the paper substrate. However, materials in which a synthetic resin film or the like is laminated onto a paper substrate have environmental issues, as it is difficult to recycle the paper and synthetic resin after use.

[0004] Therefore, progress has been made in the development of gas barrier materials that use paper as a base material without using synthetic resin films, etc. For example, Patent Document 1 proposes a paper barrier material in which a water vapor barrier layer and a gas barrier layer are provided in this order on a paper base material. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6234654 Summary of the Invention

[0006] Packaging bags are sometimes required to have visibility of the contents so that the contents and remaining amount can be seen from the outside, but the paper barrier material described in Patent Document 1 has low transparency, and there is a problem in that the visibility of the contents is poor when the material is used as a packaging bag.

[0007] Therefore, the present disclosure provides a barrier laminate that, when made into a packaging bag, has excellent visibility of the contents and good barrier properties.

[0008] <1> A barrier laminate having an anchor coat layer and a water vapor barrier layer, in this order, on at least one surface of a paper substrate, wherein the barrier laminate has a total light transmittance of 65% or more as measured in accordance with JIS K 7361-1:1997, and an arithmetic mean height of the surface on the water vapor barrier layer side of 75 μm or less as measured in accordance with JIS B 0601:2001. <2> The haze measured in accordance with JIS K 7136:2000 is 90% or less. <1> The barrier laminate according to claim 1. <3> the maximum height of the surface on the water vapor barrier layer side measured in accordance with JIS B 0601:2001 is 550 μm or less; <1> or <2> The barrier laminate according to claim 1. <4> The irregular freeness of the pulp fibers constituting the paper base material is 100 mL or more and 600 mL or less, <1> ~ <3> 10. The barrier laminate according to any one of the preceding items. <5> The coating amount of the water vapor barrier layer is 2 g / m as a solid content after drying. 2 More than 8g / m 2 Below is the <1> ~ <4> 10. The barrier laminate according to any one of the preceding items. <6> the anchor coat layer and the water vapor barrier layer are provided in this order on one surface of the paper base material, and a resin layer is provided on the other surface of the paper base material; <1> ~ <5> 10. The barrier laminate according to any one of the preceding items. <7> Water vapor permeability at 40℃ and 90%RH is 20g / m 2 ·day or less, <1> ~ <6> 10. The barrier laminate according to any one of the preceding items. <8> Oxygen permeability at 23℃ and 50%RH is 5mL / (m 2 ·24h·atm) or less, <1> ~ <7> 10. The barrier laminate according to any one of the preceding items. <9> The paper substrate is glassine paper. <1> ~ <8> 10. The barrier laminate according to any one of the preceding items. <10> The resin constituting the anchor coat layer includes a polyester resin. <1> ~ <9> 10. The barrier laminate according to any one of the preceding items. <11> the water vapor barrier layer comprises a water-dispersible resin binder, the water-dispersible resin binder contains at least one selected from the group consisting of a styrene / acrylic copolymer and an olefin / unsaturated carboxylic acid copolymer; <1> ~ <10> 10. The barrier laminate according to any one of the preceding items. <12> The water vapor barrier layer further contains a cationic resin and a layered inorganic compound. <11> The barrier laminate according to claim 1. <13> Packaging materials, <1> ~ <12> 10. The barrier laminate according to any one of the preceding items. <14> <1> ~ <12> A packaging bag comprising the barrier laminate according to any one of the preceding items. DETAILED DESCRIPTION OF THE INVENTION

[0009] Preferred embodiments of the present invention are described below. In this specification, the range "X to Y" means "X or more and Y or less." When numerical ranges are described in stages, the upper and lower limits of each numerical range can be combined arbitrarily. In this specification, unless otherwise specified, operations and measurements of physical properties are performed under conditions of room temperature (20 to 25°C) and a relative humidity of 40 to 50% RH.

[0010] <Barrier laminate> A barrier laminate according to an embodiment of the present invention (hereinafter also simply referred to as "barrier laminate") has an anchor coat layer and a water vapor barrier layer, in this order, on at least one surface of a paper substrate, and has a total light transmittance of 65% or more as measured in accordance with JIS K 7361-1:1997, and an arithmetic mean height of the surface on the water vapor barrier layer side of 75 μm or less as measured in accordance with JIS B 0601:2001. When made into a packaging bag, the barrier laminate of this embodiment has excellent visibility of the contents and good barrier properties. This embodiment will be described in detail below.

[0011] [Paper base material] In the barrier laminate of this embodiment, the irregular freeness of the pulp fibers constituting the paper base material is preferably 100 mL or more, more preferably 150 mL or more, and even more preferably 200 mL or more, from the viewpoint of the dimensional stability of the paper base material. Furthermore, the irregular freeness of the pulp fibers constituting the paper base material is preferably 600 mL or less, more preferably 500 mL or less, and even more preferably 400 mL or less, from the viewpoint of the transparency of the paper base material. Known methods can be used to beat the pulp to adjust the irregular freeness. Here, "irregular freeness" refers to the freeness (freeness) measured in the Canadian Standard Freeness Method specified in JIS P 8121:2012, with the pulp sampling amount changed from 3 g to 0.3 g and the JIS standard screen plate changed to an 80 mesh wire. The irregular freeness of the pulp constituting the paper base material is measured by the above-mentioned method using pulp disintegrated in accordance with JIS P 8220-1:2012 as a sample. In this specification, the irregular freeness of the pulp fibers constituting the paper base material is also referred to as "irregular freeness of disintegrated pulp." An example of a paper substrate in which the irregular freeness of the pulp fibers constituting the substrate is 100 mL or more and 600 mL or less is glassine paper. Among glassine papers, glassine paper that exhibits particularly high total light transmittance through high beating is also called graphene paper. Using graphene paper as the paper substrate is preferable because it allows for the production of a barrier laminate with excellent gas barrier properties without the need for an additional gas barrier layer.

[0012] Generally, glassine paper is mainly made of softwood chemical pulp, which is beaten at a high temperature and made into paper at an acidic or neutral pH, and then compressed using a supercalender, etc. Specific examples of pulp include chemical pulp made from softwoods such as spruce and hemlock, but other pulp materials such as hardwood chemical pulp, mechanical pulp, recycled paper, and synthetic pulp may also be mixed and blended.

[0013] Additives may be added to the paper substrate. Examples of additives include pH adjusters (sodium bicarbonate, sodium hydroxide, etc.), dry strength agents (polyacrylamide, starch, etc.), wet strength agents (polyamide polyamine epichlorohydrin resin, melamine-formaldehyde resin, or urea-formaldehyde resin), internal sizing agents (rosin-based, alkyl ketene dimer, etc.), drainage retention aids, antifoaming agents, fillers (calcium carbonate, talc, etc.), dyes, etc. These additives may be used alone or in combination of two or more. The content of the additives is not particularly limited and may be within a commonly used range.

[0014] (Basic weight) The basis weight of the paper substrate is not particularly limited, but for example, for packaging bag applications, it is 20 g / m 2 More than 150g / m 2 Less than 30 g / m 2 More than 100g / m 2 Less than 30 g / m is more preferable. 2 More than 50g / m 2 The following is even more preferred: The basis weight of the paper substrate is measured in accordance with JIS P 8124:2011.

[0015] (paper thickness) The thickness of the paper substrate is not particularly limited, but for example, for packaging bag applications, it is preferably 20 μm to 150 μm, more preferably 25 μm to 100 μm, and even more preferably 30 μm to 50 μm. The thickness of the paper substrate is measured in accordance with JIS P 8118:2014.

[0016] (Total light transmittance) The total light transmittance of the paper substrate is preferably 65% ​​or more, more preferably 70% or more, even more preferably 75% or more, and even more preferably 80% or more, from the viewpoint of obtaining a barrier laminate that provides excellent visibility of the contents when made into a packaging bag, and may be 100%, but from the viewpoint of easy availability, it is preferably 95% or less, more preferably 90% or less. The total light transmittance of the paper substrate is measured in accordance with JIS K 7375:2008.

[0017] (Smoothness) The smoothness of the paper substrate is not particularly limited, but the Oken smoothness of the surface of the paper substrate on which the anchor coat layer and water vapor barrier layer are to be formed is preferably 500 seconds or more and 1500 seconds or less. Furthermore, when a resin layer (described below) is formed, the Oken smoothness of the surface of the paper substrate on which the resin layer is to be formed is preferably 1000 seconds or more and 2000 seconds or less. The Oken smoothness of the paper substrate is measured in accordance with JIS P 8155:2010.

[0018] (Paper base material manufacturing method) A method for producing a paper base material includes a method of making a paper stock containing pulp. The paper stock may further contain additives, such as those listed above.

[0019] The stock can be prepared by adding additives to a pulp slurry. The pulp slurry is obtained by beating pulp in the presence of water. The pulp beating method and beating device are not particularly limited and may be the same as known beating methods and beating devices. The pulp content in the stock is not particularly limited and may be within a commonly used range. For example, it is 60% by mass or more and less than 100% by mass relative to the total mass of the stock.

[0020] Papermaking from stock can be carried out by standard methods. For example, the stock is cast onto a wire or the like, dewatered to obtain a wet paper, and multiple wet papers are stacked as necessary, and this single-layer or multi-layer wet paper is pressed and dried. In this case, if multiple wet papers are not stacked, a single-layer paper is obtained, and if multiple wet papers are stacked, a multi-layer paper is obtained. When multiple wet papers are stacked, an adhesive may be applied to the surface of the wet paper (the surface on which other wet papers are stacked).

[0021] [Anchor coat layer] The barrier laminate of this embodiment has an anchor coat layer between the paper substrate and the water vapor barrier layer.

[0022] To obtain a barrier laminate that provides excellent visibility of the contents when used as a packaging bag, it is conceivable to select a highly transparent paper substrate. However, highly transparent paper substrates (particularly graphane paper) have a large specific surface area of ​​cellulose due to extensive beating. Consequently, there are many hydrogen bonds between cellulose molecules, and water easily penetrates these sites. For this reason, when a water-based water vapor barrier layer coating liquid is applied to a highly transparent paper substrate, the coating liquid penetrates into the paper substrate, causing numerous wrinkles during the drying process (i.e., the surface roughness of the surface on the water vapor barrier layer side increases). As a result, the resulting barrier laminate has poor visibility of the contents when used as a packaging bag (Comparative Examples 1 to 4 described below). In contrast, by providing an anchor coat layer on the paper substrate and then coating the water vapor barrier layer coating liquid on top of it, the penetration of the water vapor barrier layer coating liquid into the paper substrate is suppressed, reducing the occurrence of wrinkles during the drying process (i.e., the surface roughness of the surface on the water vapor barrier layer side decreases). As a result, the resulting barrier laminate has excellent visibility of the contents when used as a packaging bag.

[0023] That is, the method for producing the barrier laminate preferably includes the following steps: (1) A process of applying an anchor coat layer coating solution, in which a resin constituting the anchor coat layer is dissolved or dispersed in an organic solvent or a mixed solvent of an organic solvent and water (more preferably an organic solvent), to at least one surface of a paper substrate and drying to form an anchor coat layer. (2) A process of applying a water vapor barrier layer coating liquid onto the obtained anchor coat layer and drying it to form a water vapor barrier layer.

[0024] The resin constituting the anchor coat layer (hereinafter also referred to as "anchor coat layer resin") is not particularly limited as long as it can exhibit the above-mentioned effects, but preferred examples include polyester resin, urethane resin, acrylic resin, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate, ethylene acrylic resin, and modified products thereof. The anchor coat layer resin preferably contains a polyester resin, and is more preferably a polyester resin. The anchor coat layer resin may be used alone or in combination of two or more types.

[0025] The resin for the anchor coat layer may be either a synthetic product or a commercially available product, and commercially available products such as those used in the examples may be used.

[0026] In addition to the resin for the anchor coat layer, other components may be added to the anchor coat layer. Examples of other components include pigments, lubricants, antifoaming agents, viscosity modifiers, leveling agents such as surfactants and alcohols, and colorants such as coloring dyes. The total content of other components is preferably 30% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, of the solid content of the anchor coat layer.

[0027] (Method for forming anchor coat layer) The method for forming the anchor coat layer is not particularly limited, but for example, the anchor coat layer can be formed by preparing an anchor coat layer coating liquid containing at least a resin for the anchor coat layer, applying the coating liquid to at least one surface of a paper substrate, and drying it. In this method, in order to suppress penetration of the anchor coat layer coating liquid into the paper substrate, it is preferable to prepare the anchor coat layer coating liquid by dissolving or dispersing the anchor coat layer resin in an organic solvent or a mixed solvent of an organic solvent and water.

[0028] The organic solvent is not particularly limited, and examples thereof include acetone, methanol, ethanol, isopropanol, n-propanol, butanol, ethyl acetate, propyl acetate, methyl ethyl ketone, methyl isobutyl ketone, toluene, propylene glycol monomethyl ether, hexane, etc. In the case of a mixed solvent of water and an organic solvent, the mass ratio of the organic solvent to water (organic solvent / water) in the anchor coat layer coating liquid is preferably 99 / 1 or more and less than 20 / 80.

[0029] The device used to apply the anchor coat layer coating solution is not particularly limited, and may be appropriately selected from commonly used coating devices, such as an air knife coater, blade coater, gravure coater, rod blade coater, roll coater, reverse roll coater, Mayer bar coater, curtain coater, die slot coater, champlex coater, metering blade type size press coater, short dwell coater, spray coater, gate roll coater, and lip coater.

[0030] The drying conditions for the anchor coat layer are not particularly limited, but the drying temperature is preferably 50 to 100° C., and the drying time is preferably 5 to 60 seconds.

[0031] The drying equipment for drying the applied anchor coat layer is not particularly limited, and known equipment can be used, such as a hot air dryer, an infrared dryer, an explosion-proof dryer, a gas burner, a hot plate, etc.

[0032] (Amount of anchor coat layer applied) The coating amount of the anchor coat layer is preferably 0.1 g / m from the viewpoint of suppressing penetration of the anchor coat layer coating solution into the paper substrate. 2 More preferably, 0.3 g / m 2 The upper limit of the coating amount of the anchor coat layer is not particularly limited, but is preferably 3.0 g / m 2 or less, more preferably 2.0 g / m 2or less, more preferably 1.0 g / m 2 The coating amount of the anchor coat layer is the coating amount after drying.

[0033] [Water vapor barrier layer] The water vapor barrier layer is a layer that has water vapor barrier properties that prevent water vapor from passing through. The barrier laminate according to this embodiment preferably has a water vapor barrier layer on at least one outermost layer of the paper substrate. By providing a water vapor barrier layer on the outermost layer, heat sealability can be achieved without providing a sealant layer.

[0034] (Water-dispersible resin binder) The water vapor barrier layer according to this embodiment preferably contains a water-dispersible resin binder. The water-dispersible resin binder is a resin binder that is not water-soluble but is finely dispersed in water, such as in an emulsion or suspension. Examples of polymers that form the backbone of the water-dispersible resin binder include polyolefin resins (polyethylene, polypropylene, etc.), vinyl chloride resins, styrene resins, styrene / butadiene copolymers, acrylonitrile / styrene copolymers, acrylonitrile / butadiene copolymers, ABS resins, AAS resins, AES resins, vinylidene chloride resins, polyurethane resins, poly-4-methylpentene-1 resins, polybutene-1 resins, vinylidene fluoride resins, vinyl fluoride resins, fluororesins, polycarbonate resins, polyamide resins, acetal resins, polyphenylene oxide resins, polyester resins (polyethylene terephthalate, polybutylene terephthalate, etc.), polyphenylene sulfide resins, polyimide resins, polysulfone resins, polyethersulfone resins, aromatic polyester resins, polyarylate resins, olefin / unsaturated carboxylic acid copolymers, and modified versions thereof. Among these, the polymer that forms the backbone of the water-dispersible resin binder of the water vapor barrier layer is preferably one or more types selected from the group consisting of styrene / butadiene copolymers, styrene / acrylic copolymers, and olefin / unsaturated carboxylic acid copolymers, and more preferably one or more types selected from the group consisting of styrene / acrylic copolymers and olefin / unsaturated carboxylic acid copolymers.

[0035] <Styrene / butadiene copolymer> Styrene-butadiene copolymers are copolymers obtained by emulsion polymerization of monomers consisting of styrene-based compounds such as styrene, α-methylstyrene, vinyltoluene, pt-butylstyrene, and chlorostyrene, and butadiene-based compounds such as 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene, as well as other compounds copolymerizable with these. As the styrene-based compound, styrene is preferred, and as the butadiene-based compound, 1,3-butadiene is preferred.

[0036] <Styrene / acrylic copolymer> Styrene / acrylic copolymers are copolymers obtained by emulsion polymerization of monomers consisting of styrene compounds such as styrene, α-methylstyrene, vinyltoluene, pt-butylstyrene, and chlorostyrene, acrylic compounds such as acrylic acid, methacrylic acid, (meth)acrylic acid esters, (meth)acrylamidopropanesulfonic acid, and (meth)acrylic acid sulfoalkyl sodium salts (the alkyl group has 2 to 3 carbon atoms), and other compounds copolymerizable with these. Styrene is preferred as the styrene compound, and acrylic acid, methacrylic acid, acrylic acid esters, and methacrylic acid esters are preferred as the acrylic compounds, with acrylic acid and acrylic acid esters being more preferred. Preferred (meth)acrylic acid esters are alkyl acrylate esters, and the alkyl group preferably has 1 to 6 carbon atoms. When the water-dispersible resin binder is a styrene / acrylic copolymer, it is also a preferred embodiment that the water vapor barrier layer is made of a styrene / acrylic copolymer.

[0037] <Olefin / unsaturated carboxylic acid copolymer> The olefin / unsaturated carboxylic acid copolymer is a copolymer obtained by emulsion polymerization of a monomer consisting of an olefin, particularly an α-olefin such as propylene, or ethylene, and an unsaturated carboxylic acid such as acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, itaconic acid, fumaric acid, maleic acid, or butenetricarboxylic acid, an unsaturated polycarboxylic acid alkyl ester having at least one carboxy group such as itaconic acid monoethyl ester, fumaric acid monobutyl ester, or maleic acid monobutyl ester, or other compound copolymerizable therewith.

[0038] The olefin is preferably ethylene or an α-olefin, more preferably ethylene, and the unsaturated carboxylic acid monomer is preferably acrylic acid, methacrylic acid, itaconic acid, fumaric acid, or the like.

[0039] As a specific example of an olefin / unsaturated carboxylic acid copolymer, for example, an aqueous dispersion of ammonium salt of ethylene-acrylic acid copolymer is commercially available under the trade name ZAIKXEN (registered trademark) AC (copolymerization ratio of acrylic acid: 20%, manufactured by Sumitomo Seika Chemicals Co., Ltd.), and is easily available and usable. When the water vapor barrier layer contains a cationic resin and a layered inorganic compound, the water-dispersible resin binder is preferably an anionic binder. Examples of anionic binders include binders containing monomer units containing an anionic group. Among these, the anionic binder is preferably a binder containing monomer units containing a carboxy group. As described below, the planar portion of the layered inorganic compound is anionic, but when the cationic resin is adsorbed, the surface becomes cationic, which is thought to result in increased affinity with the anionic binder. Examples of anionic binders include the above-mentioned olefin / unsaturated carboxylic acid copolymers.

[0040] The olefin / unsaturated carboxylic acid copolymer preferably has an unsaturated carboxylic acid monomer unit content of 1 mol% or more, more preferably 10 mol% or more, and preferably 50 mol% or less, more preferably 30 mol% or less. When the unsaturated carboxylic acid monomer content is within the above range, the dispersibility of the layered inorganic compound is excellent.

[0041] The weight average molecular weight of the water-dispersible resin binder is preferably 10,000 or more, more preferably 20,000 or more, and is preferably 10,000,000 or less, more preferably 5,000,000 or less, from the viewpoint of viscosity and strength when applied to a paper substrate.

[0042] The content of the water-dispersible resin binder is not particularly limited, but is preferably 20% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, and even more preferably 70% by mass or more, of the total solid content in the water vapor barrier layer. The content of the water-dispersible resin binder is preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 85% by mass or less, and particularly preferably 80% by mass or less, relative to the mass of the total solid content in the water vapor barrier layer.

[0043] (layered inorganic compounds) The water vapor barrier layer preferably contains a layered inorganic compound. The layered inorganic compound is flat. A mixed solution of the layered inorganic compound, a cationic resin, and a water-dispersible resin binder is prepared and coated on a paper substrate to form a water vapor barrier layer. Within the water vapor barrier layer, the flat layered inorganic compounds are arranged in a stacked state approximately parallel to the plane (surface) of the paper substrate. This reduces the area where the layered inorganic compounds are not present in the plane direction, thereby suppressing water vapor permeation. Furthermore, in the thickness direction, the flat layered inorganic compounds are arranged parallel to the plane of the paper substrate, so water vapor permeates through the layer while bypassing the layered inorganic compounds, creating a maze effect that suppresses water vapor permeation. As a result, the water vapor barrier layer can exhibit excellent water vapor barrier properties.

[0044] The average thickness of the layered inorganic compound is preferably 200 nm or less. The average thickness of the layered inorganic compound is preferably 120 nm or less, more preferably 50 nm or less, even more preferably 25 nm or less, and particularly preferably 10 nm or less. The smaller the thickness of the layered inorganic compound, the greater the number of layers of the layered inorganic compound in the water vapor barrier layer, and therefore the greater the water vapor barrier property that can be exhibited. The lower limit of the thickness of the layered inorganic compound is not particularly limited, but is preferably 2 nm or more. Here, the average thickness of the layered inorganic compound contained in the water vapor barrier layer is determined as follows: A magnified photograph of the cross section of the water vapor barrier layer is taken using an electron microscope. The magnification is set so that approximately 20 to 30 layered inorganic compounds are included in the image. The thickness of each layered inorganic compound in the image is measured. The average value of the obtained thicknesses is then calculated to be the average thickness of the layered inorganic compound.

[0045] The average length of the layered inorganic compound is preferably 1 μm or more and 100 μm or less. When the average length is 1 μm or more, the layered inorganic compound is more likely to be aligned parallel to the paper substrate. Furthermore, when the average length is 100 μm or less, there is less concern that a portion of the layered inorganic compound will protrude from the water vapor barrier layer. The average length of the layered inorganic compound is more preferably 50 μm or less, even more preferably 30 μm or less, and particularly preferably 15 μm or less. The average length of the layered inorganic compound contained in the water vapor barrier layer is determined as follows: A magnified photograph of the cross section of the water vapor barrier layer is taken using an electron microscope. The magnification is set so that approximately 20 to 30 layered inorganic compounds are included in the image. The length of each layered inorganic compound within the image is measured. The average of the lengths obtained is then calculated to determine the average length of the layered inorganic compound. The length of the layered inorganic compound is sometimes referred to as particle diameter.

[0046] The layered inorganic compound preferably has an aspect ratio of 50 or more. An aspect ratio of 50 or more makes it possible to achieve a predetermined water vapor barrier property. The aspect ratio of the layered inorganic compound is preferably 80 or more, more preferably 300 or more, and particularly preferably 500 or more. The higher the aspect ratio, the more water vapor permeation is suppressed and the water vapor barrier property is improved. Furthermore, the higher the aspect ratio, the less the amount of layered inorganic compound added can be reduced. There is no particular upper limit for the aspect ratio, and from the viewpoint of the viscosity of the coating liquid, it is preferably about 10,000 or less, more preferably about 5,000 or less, and even more preferably about 2,000 or less. Here, the aspect ratio is, as described above, the value obtained by taking an enlarged photograph of the cross section of the water vapor barrier layer using an electron microscope and dividing the average length of the layered inorganic compound obtained by the average thickness.

[0047] Specific examples of layered inorganic compounds include mica such as mica group and brittle mica group, bentonite, kaolinite (kaolin mineral), pyrophyllite, talc, smectite, vermiculite, chlorite, septe chlorite, serpentine, stilpnomelane, and montmorillonite.

[0048] Among these, it is particularly preferable to contain one or more of mica, bentonite, and kaolin from the viewpoint of improving barrier properties, and mica or bentonite is more preferable. Specific examples of mica include synthetic mica (e.g., swelling mica, non-swelling mica), white mica (muscovite), sericite (sericite), phloxopite (phlocopite), biotite (biotite), fluorphlogopite (artificial mica), red mica, soda mica, vanadium mica, illite, zinc mica, paragonite, brittle mica, etc. Specific examples of bentonite include montmorillonite.

[0049] The content of the layered inorganic compound is preferably 80% by mass or less, more preferably 50% by mass or less, even more preferably 30% by mass or less, and particularly preferably 20% by mass or less, based on the total solid content of the water vapor barrier layer. Meanwhile, the content of the layered inorganic compound is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 2% by mass or more, and even more preferably 5% by mass or more. By increasing the aspect ratio of the layered inorganic compound and reducing the thickness, the content of the layered inorganic compound can be reduced. Furthermore, the strength of the water vapor barrier layer can be increased, thereby preventing the layered inorganic compound from falling off from the water vapor barrier layer.

[0050] (cationic resin) The water vapor barrier layer preferably contains a cationic resin. By containing a cationic resin, the water vapor barrier layer has significantly improved water vapor barrier properties. The reasons for this are believed to be as follows. (1) It is known that layered inorganic compounds tend to be anionic at the flat surfaces and cationic at the edges, forming a so-called house-of-cards structure in which the layered inorganic compounds are sterically aggregated with each other. This house-of-cards structure makes aqueous dispersions of layered inorganic compounds very viscous. (2) On the other hand, the house-of-card structure easily breaks when force is applied, such as by stirring, and therefore aqueous dispersions of layered inorganic compounds exhibit thixotropy. (3) When an appropriate cationic resin is added to an aqueous dispersion of a layered inorganic compound, the cationic resin adsorbs onto the anionic planar portions of the layered inorganic compound, destroying the house-of-cards structure. As a result, the layered inorganic compound is prevented from aggregating three-dimensionally, making it easier for the flat-plate-shaped layered inorganic compound to be layered parallel to the plane of the paper substrate, leading to improved water vapor barrier properties.

[0051] Specific examples of cationic resins include polyalkylene polyamines, polyamide compounds, modified polyamide compounds, polyamidoamine-epihalohydrin or formaldehyde condensation reaction products, polyamine-epihalohydrin or formaldehyde condensation reaction products, polyamide polyurea-epihalohydrin or formaldehyde condensation reaction products, polyamine polyurea-epihalohydrin or formaldehyde condensation reaction products, polyamidoamine polyurea-epihalohydrin or formaldehyde condensation reaction products, polyamide polyurea compounds, polyamine polyurea compounds, polyamidoamine polyurea compounds, polyamidoamine compounds, polyethyleneimine, polyvinylpyridine, amino-modified acrylamide compounds, polyvinylamine, and polydiallyldimethylammonium chloride. Among these, the cationic resin is preferably a modified polyamide compound, more preferably a modified polyamide resin. As the modified polyamide resin, a commercially available product such as SPI203(50)H manufactured by Taoka Chemical Co., Ltd. may be used.

[0052] The content of the cationic resin in the water vapor barrier layer may be selected appropriately depending on the types of layered inorganic compound and water-dispersible resin binder used in the water vapor barrier layer, but from the viewpoint of improving barrier properties, the content is preferably from 1 to 300 parts by mass, more preferably from 3 to 250 parts by mass, even more preferably from 5 to 200 parts by mass, particularly preferably from 10 to 150 parts by mass, and most preferably from 20 to 100 parts by mass, relative to 100 parts by mass of the layered inorganic compound.

[0053] Furthermore, the content of the cationic resin is preferably from 0.1 to 20 parts by mass, more preferably from 0.3 to 15 parts by mass, and even more preferably from 1 to 15 parts by mass, relative to 100 parts by mass of the water-dispersible resin binder in the water vapor barrier layer.

[0054] The water vapor barrier layer preferably contains a water-dispersible resin binder and, as needed, a layered inorganic compound and a cationic resin. In addition to the layered inorganic compound, cationic resin, and water-dispersible resin binder, the water vapor barrier layer may also contain, as needed, appropriate additives such as dispersants, surfactants, defoamers, wetting agents, dyes, color adjusters, and thickeners.

[0055] (Water vapor barrier layer coating amount) The coating amount of the water vapor barrier layer is 1 g / m2 as the solid content after drying. 2 More preferably, 2 g / m 2 and preferably 15 g / m 2 or less, more preferably 10 g / m 2 or less, more preferably 8 g / m 2 and even more preferably 5 g / m 2 The following is the result.

[0056] (Method for forming a water vapor barrier layer)

[0033] The method for forming the water vapor barrier layer is not particularly limited, but it is preferable to form the water vapor barrier layer by applying and drying a water vapor barrier layer coating liquid in which a water-dispersible resin binder, and optionally a layered inorganic compound and a cationic resin, are dispersed in a solvent.

[0057] The equipment used for coating and drying is not particularly limited, and examples thereof include those exemplified in the above section (Method for forming anchor coat layer).

[0058] The solvent for the water vapor barrier layer coating liquid is not particularly limited, and can be water or an organic solvent such as ethanol, isopropyl alcohol, methyl ethyl ketone, toluene, etc. Among these, water is preferred as the dispersion medium for the water vapor barrier layer coating liquid, from the viewpoint of avoiding the problems associated with volatile organic solvents.

[0059] [Resin layer] The barrier laminate according to this embodiment preferably has a resin layer on the other side of the paper substrate (the side on which the water vapor barrier layer is not provided) in order to further improve transparency. That is, it is preferable that the paper substrate has an anchor coat layer and a water vapor barrier layer in this order on one side, and a resin layer on the other side of the paper substrate. By providing a resin layer on the other side of the paper substrate, it is thought that the surface irregularities of the paper substrate are covered, light scattering is suppressed, and transparency is improved.

[0060] The resin constituting the resin layer (hereinafter also referred to as "resin for resin layer") is not particularly limited, but is preferably one that has the effect of improving the transparency or smoothness of the paper base material, such as varnish, acrylic resin, urethane resin, polyester resin, ethylene acrylic resin, etc. Urethane resin is preferred. The resin for the resin layer may be used alone or in combination of two or more types.

[0061] The resin for the resin layer may be either a synthetic product or a commercially available product, and commercially available products such as those used in the examples may be used.

[0062] In addition to the resin for the resin layer, other components may be added to the resin layer. Examples of other components include metal powder, pigments, lubricants, antifoaming agents, viscosity modifiers, surfactants, leveling agents such as alcohol, and colorants such as coloring dyes. In another preferred embodiment, the resin layer contains, for example, zinc oxide powder as an ultraviolet inhibitor. The barrier laminate preferably has an ultraviolet transmittance of 0 to 25%, more preferably 1 to 4%, at a wavelength of 350 nm when the light incident surface is the surface on the water vapor barrier layer side.

[0063] (Method of forming resin layer) The resin layer can be obtained by preparing a resin layer coating liquid containing at least a resin for the resin layer, applying the coating liquid to at least one surface of a paper substrate, and drying the coating liquid. In the present invention, the resin for the resin layer is prepared by dissolving or dispersing it in an organic solvent or a mixed solvent of an organic solvent and water, and then coating the coating liquid on the paper substrate.

[0064] The solvent for the resin layer coating liquid is an organic solvent or a mixed solvent of an organic solvent and water. The organic solvent is not particularly limited, but examples thereof include those exemplified in the above section (Method for forming an anchor coat layer). In the case of a mixed solvent of water and an organic solvent, the mass ratio of the organic solvent to water (organic solvent / water) in the resin layer coating liquid is preferably 99 / 1 or more and less than 20 / 80.

[0065] The apparatus used for coating and drying the resin layer is not particularly limited, and examples thereof include those exemplified in the above section (Method for forming anchor coat layer).

[0066] The drying conditions for the resin layer are not particularly limited, but the drying temperature is preferably 50 to 100° C., and the drying time is preferably 5 to 60 seconds.

[0067] (Coating amount of resin layer) The coating amount of the resin layer is preferably 0.1 g / m from the viewpoint of suppressing the penetration of the water vapor barrier layer coating solution into the paper substrate. 2 More preferably, 0.3 g / m 2 The upper limit of the coating amount of the anchor coat layer is not particularly limited, but is preferably 3.0 g / m 2 or less, more preferably 2.0 g / m 2 or less, more preferably 1.0 g / m 2 The coating amount of the anchor coat layer is the coating amount after drying.

[0068] [Sealant layer] The barrier laminate may further have a sealant layer on at least one of the outermost layers.

[0069] The sealant layer is a layer that melts and bonds by heating, ultrasonic waves, etc. The sealant layer preferably contains a water-dispersible resin or a biodegradable resin. Examples of water-dispersible resins include those mentioned above as the polymer that forms the backbone of the water-dispersible resin binder of the water vapor barrier layer.

[0070] ≪Biodegradable resin≫ The biodegradable resin is not particularly limited, but examples thereof include polylactic acid, polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, and 3-hydroxybutanoic acid / 3-hydroxyhexanoic acid copolymer.

[0071] Commercially available biodegradable resins may be used, such as polylactic acid, such as "Landy PL Series (product name)" manufactured by Miyoshi Oil & Fats Co., Ltd.

[0072] The thickness of the sealant layer is preferably 1 μm or more, more preferably 3 μm or more, and is preferably 50 μm or less, more preferably 30 μm or less. The coating amount of the sealant layer is preferably 0.5 g / m2 in terms of solid content. 2 More preferably, 1 g / m 2 and preferably 50 g / m 2 Less than 30 g / m, more preferably 2 or less, and more preferably 10 g / m 2 The following is the result.

[0073] <Properties of Barrier Laminate> (Water vapor permeability) The lower the water vapor permeability of the barrier laminate, the less water vapor is transmitted, and the water vapor permeability at 40°C and 90% RH is preferably 100 g / m 2 ·day or less, preferably 50g / m 2 ·day or less, more preferably 30 g / m 2 day or less, even more preferably 20 g / m 2 15 g / m or less per day, particularly preferably 15 g / m2 ·day or less. The lower the water vapor permeability, the better. Therefore, the lower limit is not particularly limited, but it is preferably 0 g / m 2 ·day or more, 0.1g / m 2 ·day or more, 0.5g / m 2 The water vapor permeability of the barrier laminate is measured by the method described in the Examples. The water vapor permeability can be controlled, for example, by selecting the thickness of the water vapor barrier layer and / or the components contained in the water vapor barrier layer.

[0074] (oxygen permeability) The lower the oxygen permeability of the barrier laminate, the less oxygen is permeated, and the oxygen permeability at 23°C and 50% RH is preferably 20 mL / m 2 ·24h·atm or less, preferably 10mL / m 2 24h atm or less, more preferably 5mL / m 2 24h atm or less, even more preferably 3mL / m 2 24h atm or less, particularly preferably 2mL / m 2 The oxygen permeability of the barrier laminate is measured by the method described in the Examples. The lower the oxygen permeability, the better, so there is no particular lower limit, but it is preferably 0 mL / m 2 ·24h·atm or more, 0.1mL / m 2 ·24h atm or more, 0.5mL / m 2 The oxygen permeability can be controlled, for example, by the thickness and / or type of the paper substrate.

[0075] (Total light transmittance) The total light transmittance of the barrier laminate according to this embodiment is 65% or more, preferably 70% or more, more preferably 75% or more, even more preferably 80% or more, and even more preferably 82% or more, from the viewpoint of visibility of the contents when made into a packaging bag. The upper limit of the total light transmittance of the barrier laminate is not particularly limited, but is usually 100% or less, preferably 95% or less, and more preferably 90% or less. The total light transmittance of the barrier laminate is measured in accordance with JIS K 7361-1:1997. The total light transmittance can be controlled, for example, by the thickness and / or type of the paper substrate.

[0076] (Hayes) The haze of the barrier laminate according to this embodiment is preferably 90% or less, more preferably 85% or less, and even more preferably 80% or less, from the viewpoint of visibility of the contents when used as a packaging bag. The lower limit of the haze of the barrier laminate is not particularly limited, but is usually 0% or more, preferably 10% or more, more preferably 20% or more, even more preferably 50% or more, and even more preferably 70% or more. The haze of the barrier laminate is measured in accordance with JIS K 7136:2000. The haze of the barrier laminate can be controlled, for example, by the thickness and / or smoothness (surface roughness) of the coating layer (anchor coat layer and water vapor barrier layer). The smoothness (surface roughness) of the coating layer can be controlled by the coating method of the coating layer. Alternatively, the haze of the barrier laminate can also be controlled by the thickness and / or type of the paper substrate.

[0077] (surface roughness) From the viewpoint of visibility of the contents when the barrier laminate according to this embodiment is made into a packaging bag, the surface roughness of the barrier laminate according to this embodiment is, in terms of the arithmetic mean height of the surface on the water vapor barrier layer side measured in accordance with JIS B 0601:2001, 75 μm or less, preferably 70 μm or less. There is no particular lower limit, but it is preferably 0 μm or more, 20 μm or more, 30 μm or more, or 50 μm or more. The surface on the water vapor barrier layer side refers to the surface on the side where the water vapor barrier layer is present, relative to the paper substrate. The arithmetic mean height can be controlled, for example, by the coating method of the coating layers (anchor coat layer and water vapor barrier layer) (for example, by selecting a coating method that provides high surface smoothness, such as bar coating or blade coating) and / or by calendaring the paper substrate.

[0078] From the viewpoint of visibility of the contents when the barrier laminate according to this embodiment is made into a packaging bag, the maximum height of the surface on the water vapor barrier layer side measured in accordance with JIS B 0601:2001 is preferably 550 μm or less, more preferably 500 μm or less. There is no particular lower limit, but it is preferably 0 μm or more, 150 μm or more, or 250 μm or more. The maximum height can be controlled, for example, by the coating method of the coating layer (anchor coat layer and water vapor barrier layer) (for example, by selecting a coating method that provides high surface smoothness, such as bar coating or blade coating) and / or by calendaring the paper substrate.

[0079] <Application> The barrier laminate of this embodiment, when made into a packaging bag, has excellent visibility of the contents, and can be suitably used as a packaging material for food, cosmetics, daily necessities, detergents, soaps, powders, precision machinery, etc. Therefore, the present invention also provides a packaging bag made using the above-mentioned barrier laminate. [Example]

[0080] The following examples are provided to specifically explain the present invention, but the present invention is not limited to these examples. Unless otherwise specified, the following operations were carried out under conditions of 25°C and a relative humidity of 50%RH. In the examples and comparative examples, "parts" and "%" refer to "parts by mass" and "% by mass," respectively, unless otherwise specified.

[0081] Example 1 To 30.0 parts of an aqueous dispersion of a plate-like inorganic compound (swellable mica, average particle size 6.3 μm, aspect ratio approximately 1000, average thickness approximately 5 nm, solids content 6%, product name: NTS-10NC, manufactured by Topy Industries), 34.2 parts of an aqueous emulsion of ethylene / acrylic acid copolymer (solids content 29.2%, product name: ZAIKXEN AC, manufactured by Sumitomo Seika Chemicals) was added with stirring. 2.55 parts of a modified polyamide resin (solids content 53%, product name: SPI203(50)H, manufactured by Taoka Chemical Co., Ltd.) was added as a cationic resin and stirred. 0.50 parts of a 25% aqueous ammonia solution was then added and stirred. Dilution water was added to adjust the solids concentration to 17%, preparing Water Vapor Barrier Layer Coating Solution A. A solvent-based anchor coating agent containing polyester resin (AFUL No. 107 (Tokyo Ink Co., Ltd.), solvent: ethyl acetate, propyl acetate, methyl ethyl ketone, solid content: 5-10%) was applied to a paper substrate, Graphan paper (Oji F-Tex Co., Ltd., disintegrated pulp, irregular freeness 250 mL, basis weight 35 g / m). 2 , paper thickness 32 μm, total light transmittance 82.5%), low smoothness surface (Oken smoothness 1290 seconds), coating weight after drying 0.5 g / m 2 After coating with a Mayer bar so that the coating temperature was as follows, the coating was dried in an explosion-proof dryer at 80°C for 10 seconds to form an anchor coat layer. Furthermore, a water vapor barrier layer was formed on top of the anchor coat layer by applying water vapor barrier layer coating solution A at a coating weight of 3.0 g / m2 after drying. 2 After coating with a Mayer bar so that the coating was as follows, the coating was dried in a hot air dryer at 120°C for 1 minute to form a water vapor barrier layer, thereby obtaining a barrier laminate.

[0082] <Example 2> A barrier laminate was produced in the same manner as in Example 1, except that a styrene-acrylic resin aqueous dispersion (solid content: 40%, product name: XP8812, manufactured by Seiko PMC Corporation) was used instead of the water vapor barrier layer coating solution A.

[0083] Example 3 A solvent-based urethane resin-containing UV cut agent (zinc oxide dispersion, solvent: ethyl acetate, propyl acetate, isopropyl alcohol, etc., solid content: 20-30%, product name: LG-UV Cut Agent Z, manufactured by Tokyo Ink Co., Ltd.) was applied to the surface of the barrier laminate obtained in Example 1 on which the water vapor barrier layer was not provided (highly smooth surface of graphan paper, Oken smoothness: 1710 seconds) in a coating amount of 0.5 g / m after drying. 2 After coating so that the resin layer was formed, the coating was dried in an explosion-proof dryer at 80° C. for 10 seconds to obtain a barrier laminate.

[0084] Example 4 A solvent-based urethane resin-containing UV cut agent (zinc oxide dispersion, solvent: ethyl acetate, propyl acetate, isopropyl alcohol, etc., solid content: 20-30%, product name: LG-UV Cut Agent Z, manufactured by Tokyo Ink Co., Ltd.) was applied to the surface of the barrier laminate obtained in Example 2 on which the water vapor barrier layer was not provided (highly smooth surface of graphan paper, Oken smoothness: 1710 seconds) in a coating amount of 0.5 g / m after drying. 2 After coating so that the resin layer was formed, the coating was dried in an explosion-proof dryer at 80° C. for 10 seconds to obtain a barrier laminate.

[0085] <Comparative Example 1> The paper base material is Graphan paper (manufactured by Oji F-Tex Co., Ltd., disintegrated pulp with an irregular freeness of 250 mL and a basis weight of 35 g / m 2 , paper thickness 32 μm, total light transmittance 82.5%), low smoothness surface (Oken smoothness 1290 seconds), water vapor barrier layer coating solution A was applied as a water vapor barrier layer with a coating amount of 3.0 g / m after drying. 2 After coating with a Mayer bar so that the coating was as follows, the coating was dried in a hot air dryer at 120°C for 1 minute to form a water vapor barrier layer, thereby obtaining a barrier laminate.

[0086] <Comparative Example 2> A barrier laminate was produced in the same manner as in Comparative Example 1, except that a styrene-acrylic resin aqueous dispersion (solid content: 40%, product name: XP8812, manufactured by Seiko PMC Corporation) was used instead of the water vapor barrier layer coating solution A.

[0087] <Comparative Example 3> A solvent-based UV cut agent (zinc oxide dispersion, solvent: ethyl acetate, propyl acetate, isopropyl alcohol, etc., solid content: 20 to 30%, product name: LG-UV Cut Agent Z, manufactured by Tokyo Ink Co., Ltd.) was applied to the surface of the barrier laminate obtained in Comparative Example 1 on which the water vapor barrier layer was not provided (the highly smooth surface of the graphane) in a coating amount of 0.5 g / m after drying. 2 After coating so that the resin layer was formed, the coating was dried in an explosion-proof dryer at 80° C. for 10 seconds to obtain a barrier laminate.

[0088] <Comparative Example 4> A solvent-based UV cut agent (zinc oxide dispersion, solvent: ethyl acetate, propyl acetate, isopropyl alcohol, etc., solid content: 20 to 30%, product name: LG-UV Cut Agent Z, manufactured by Tokyo Ink Co., Ltd.) was applied to the surface of the barrier laminate obtained in Comparative Example 2 on which the water vapor barrier layer was not provided (the highly smooth surface of the graphane) in a coating amount of 0.5 g / m after drying. 2 After coating so that the resin layer was formed, the coating was dried in an explosion-proof dryer at 80° C. for 10 seconds to obtain a barrier laminate.

[0089] <Comparative Example 5> The paper base material was bleached kraft paper (manufactured by Oji Materia Co., Ltd., irregular freeness of the pulp constituting it: 700 mL, basis weight: 50 g / m 2 An anchor coat layer and a water vapor barrier layer were formed on one side of the paper substrate in the same manner as in Example 1, except that the paper thickness was 60 μm and the total light transmittance was 47%), to produce a barrier laminate.

[0090] <Comparative Example 6> The paper base material was bleached kraft paper (manufactured by Oji Materia Co., Ltd., irregular freeness of the pulp constituting it: 700 mL, basis weight: 50 g / m 2An anchor coat layer and a water vapor barrier layer were formed on one side of the paper substrate in the same manner as in Example 2, except that the paper thickness was 60 μm and the total light transmittance was 47%), to produce a barrier laminate.

[0091] <Evaluation> (1) Total light transmittance In accordance with JIS K 7361-1:1997, the total light transmittance of the transparent barrier laminate was measured using a haze meter HM-150 (manufactured by Murakami Color Research Laboratory Co., Ltd.) with the water vapor barrier layer facing the light incident surface, and used as an index of transparency. A total light transmittance of 65% or higher was judged to be good.

[0092] (2) Hayes In accordance with JIS K 7136:2000, the haze of the barrier laminate was measured using a haze meter HM-150 (manufactured by Murakami Color Research Laboratory Co., Ltd.) with the light incident surface facing the water vapor barrier layer, and used as an index of transparency. A haze of 90% or less was judged to be good.

[0093] (3) Surface roughness Using a one-shot 3D shape measuring instrument (Keyence Corporation, VR-3000), the arithmetic mean height and maximum height of the surface on the water vapor barrier layer side were measured in accordance with JIS B 0601:2001, and used as an index of the surface roughness of the barrier laminate. The larger each value, the more wrinkles there were in the paper, and an arithmetic mean height of 75 μm or less and a maximum height of 550 μm or less was considered to have few wrinkles.

[0094] (4) Ultraviolet transmittance Using an automatic absolute reflectance measurement unit of an ultraviolet-visible-near-infrared spectrophotometer (JASCO Corporation, V-770DS), the transmittance at a wavelength of 350 nm was determined as the ultraviolet transmittance, with the light incident surface facing the water vapor barrier layer.

[0095] (5) Oxygen permeability Using an oxygen permeability measuring device (OX-TRAN2 / 22 manufactured by MOCON), the oxygen permeability of the barrier laminate was measured under atmospheric pressure, a temperature of 23°C, and a relative humidity of 50% (low humidity conditions). The lower the oxygen permeability value, the better the oxygen barrier property.

[0096] (6) Water vapor permeability Measurements were taken with the water vapor barrier layer facing inward according to JIS-Z-0208 (cup method) B method (40°C ± 0.5°C, relative humidity 90% ± 2%). The standard for water vapor permeability is 50 g / m². 2 If the durability is 24 hours or less, it can be said that the barrier laminate is practical.

[0097] (7) Visibility The visibility of the barrier laminates obtained in the Examples and Comparative Examples was evaluated by visually checking the visibility of the contents when the laminates were molded into bags. A: It is transparent and the contents can be easily seen. B: It is transparent, but the contents are difficult to see. C: It is not transparent and the contents cannot be seen.

[0098] [Table 1]

[0099] [Table 2]

[0100] The results are shown in Table 1 above. The barrier laminates of Examples 1 to 4, when made into packaging bags, had excellent visibility of the contents and good water vapor barrier properties and gas barrier properties. Compared to Examples 1 to 4, the surface roughness was reduced by providing a resin layer on the other side of the paper substrate. This is thought to be because solvent coating on both sides of the paper substrate suppressed the warping that occurs when coating only one side. On the other hand, the barrier laminates of Comparative Examples 1 to 4, in which the water vapor barrier layer was aqueous-coated without being coated with an anchor coating agent, developed wrinkles during the drying process, and the visibility of the contents was poor when made into packaging bags. Furthermore, the barrier laminates of Comparative Examples 5 and 6, in which bleached kraft paper was used instead of graphene paper as the paper substrate, had poor visibility of the contents when made into packaging bags, and also had poor gas barrier properties.

Claims

1. A barrier laminate having an anchor coat layer and a water vapor barrier layer in this order on at least one surface of a paper substrate, The total light transmittance measured in accordance with JIS K 7361-1:1997 is 65% or more, a barrier laminate, wherein the arithmetic mean height of the surface on the water vapor barrier layer side measured in accordance with JIS B 0601:2001 is 20 μm or more and 75 μm or less.

2. 2. The barrier laminate according to claim 1, which has a haze of 90% or less as measured in accordance with JIS K 7136:2000.

3. 3. The barrier laminate according to claim 1, wherein the maximum height of the surface on the water vapor barrier layer side measured in accordance with JIS B 0601:2001 is 550 μm or less.

4. 4. The barrier laminate according to claim 1, wherein the irregular freeness of the pulp fibers constituting the paper base material is 100 mL or more and 600 mL or less.

5. The coating amount of the water vapor barrier layer is 2 g / m as a solid content after drying. ２ 8g / m or more ２ The barrier laminate according to any one of claims 1 to 4, wherein:

6. The paper substrate has the anchor coat layer and the water vapor barrier layer in this order on one surface thereof, The barrier laminate according to any one of claims 1 to 5, further comprising a resin layer on the other surface of the paper substrate.

7. Water vapor permeability at 40°C and 90% RH is 20 g / m ２ The barrier laminate according to any one of claims 1 to 6, wherein the average dry time is 100 minutes or less.

8. Oxygen permeability at 23°C and 50% RH is 5 mL / m ２ The barrier laminate according to any one of claims 1 to 7, wherein the resistance is 24h·atm or less.

9. The barrier laminate according to any one of claims 1 to 8, wherein the paper substrate is glassine paper.

10. 10. The barrier laminate according to claim 1, wherein the resin constituting the anchor coat layer comprises a polyester resin.

11. the water vapor barrier layer comprises a water-dispersible resin binder, The barrier laminate according to any one of claims 1 to 10, wherein the water-dispersible resin binder comprises at least one selected from the group consisting of a styrene / acrylic copolymer and an olefin / unsaturated carboxylic acid copolymer.

12. The barrier laminate according to claim 11, wherein the water vapor barrier layer further comprises a cationic resin and a layered inorganic compound.

13. The barrier laminate according to any one of claims 1 to 12, wherein the water vapor barrier layer is a coating layer.

14. The barrier laminate according to any one of claims 1 to 13, which is a packaging material.

15. A packaging bag comprising the barrier laminate according to any one of claims 1 to 13.

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