Laminate, method for producing laminate, packaging bag, and packaging body

Abstract

A laminate of the present disclosure has a substrate and a barrier layer containing a barrier composition. The barrier composition contains a water-soluble polymer, an inorganic layered compound, and at least one of a metal alkoxide and a hydrolysate thereof. The mass ratio of the water-soluble polymer to the inorganic layered compound in the barrier composition is from 0.3 to 3.0 (inclusive).

Description

Technical Field

[0001] The present disclosure relates to a laminate, a method for producing the laminate, a packaging bag, and a packaging body. Background Art

[0002] Packaging bags used to package contents require barrier properties to prevent the contents from deteriorating in quality. Therefore, various barrier laminates that have barrier properties against oxygen and water vapor, which significantly affect quality deterioration, have been studied as materials for packaging bags.

[0003] Patent Document 1 discloses a technique for improving the barrier properties of packaging materials by sequentially laminating a transparent primer layer, a vapor-deposited film layer, and a barrier composite coating on one side of a polypropylene substrate. Patent Document 2 discloses a barrier laminate formed by laminating two barrier layers of different compositions. Furthermore, Patent Document 3 discloses a laminate film comprising a resin substrate, a base layer, and a coating layer, wherein an inorganic layered compound is used in the coating layer.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2000-254994

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 2020-069801

[0008] Patent Document 3: International Publication No. 2016 / 158794 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] From the perspective of improving barrier properties against water vapor and oxygen, providing a barrier-resistant vapor-deposited film layer or laminating two barrier layers in a laminate complicates the process and increases manufacturing costs. On the other hand, when barrier properties are achieved through a single layer without using a vapor-deposited film layer, the film thickness may increase to achieve sufficient barrier properties, potentially reducing coating adaptability. The present disclosure provides a laminate coated on a substrate and having sufficient barrier properties against oxygen and water vapor, and a method for manufacturing the laminate. The present disclosure also provides packaging bags and packaging bodies comprising such a laminate.

[0011] Means for solving problems

[0012] One aspect of the present disclosure provides a laminate having a substrate and a barrier layer formed from a barrier composition, wherein the barrier composition includes a water-soluble polymer, an inorganic layered compound, and at least one of a metal alkoxide and a hydrolyzate thereof, wherein the mass ratio of the water-soluble polymer to the inorganic layered compound in the barrier composition is greater than or equal to 0.3 and less than or equal to 3.0.

[0013] The mass ratio of the water-soluble polymer to the inorganic layered compound in the barrier composition of the laminate is 0.3 to 3.0. Such a laminate has a barrier layer containing a water-soluble polymer and an inorganic layered compound that contribute to barrier properties against oxygen and water vapor in a balanced manner, and can exhibit sufficiently high barrier properties against oxygen and water vapor even if the barrier layer on the substrate is a single layer.

[0014] One aspect of the present disclosure provides a method for manufacturing a laminate, comprising: preparing a raw material composition comprising a water-soluble polymer, an inorganic layered compound, and at least one of a metal alkoxide and a hydrolyzate thereof, wherein the mass ratio of the water-soluble polymer to the inorganic layered compound is from 0.3 to 3.0; applying a dispersion comprising the raw material composition onto a substrate; and forming a barrier layer comprising a barrier composition from the dispersion by heating.

[0015] The above-described method for producing a laminate can provide a laminate having a barrier layer comprising the above-described barrier composition on a substrate. Consequently, vapor deposition and other barrier layer coating steps are unnecessary, simplifying the production process and reducing equipment costs. Furthermore, the laminate obtained by the above-described production method exhibits sufficiently high barrier properties against oxygen and water vapor.

[0016] One aspect of the present disclosure provides a packaging bag including the above-mentioned laminate. The packaging bag including the above-mentioned laminate can provide a packaging bag having sufficiently high barrier properties against water vapor and oxygen.

[0017] One aspect of the present disclosure provides a package comprising the packaging bag described above and a content contained in a container of the packaging bag. The package can sufficiently suppress quality degradation of the content caused by water vapor and oxygen by containing the content in the packaging bag having the laminate.

[0018] Effects of the Invention

[0019] One aspect of the present disclosure can provide a laminate coated on a substrate and having sufficient barrier properties against oxygen and water vapor, and a method for producing the laminate. Furthermore, the present disclosure can provide a packaging bag and a packaging body including such a laminate. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] [Figure 1 ] is a schematic diagram of a cross section of a stacked body.

[0021] [ Figure 2 ] is a schematic diagram of the packaging bag.

[0022] [ Figure 3 ] is a graph showing the light transmittance of the laminated bodies of Examples 1, 3, 8, 10 and Comparative Example 2. DETAILED DESCRIPTION

[0023] Hereinafter, embodiments of the present disclosure will be described. However, the following embodiments are examples for illustrating the present disclosure and are not intended to limit the present disclosure to the following contents. The upper limit or lower limit of the numerical range explicitly stated in this specification can be replaced with any value shown in the examples. In the present disclosure, the numerical range expressed in the form of "a to b" is a numerical range with a lower limit of a, an upper limit of b, and including a and b. In addition, the upper limit and lower limit values recorded individually can also be combined arbitrarily. Unless otherwise specified, the materials or components exemplified in this specification can be used alone or in combination of two or more. In the description, the same symbols are marked for the same elements or elements with the same function, and repeated descriptions are omitted. In addition, unless otherwise specified, the positional relationships such as up, down, left, and right used in the description are set as the positional relationships shown in the drawings.

[0024] Figure 1 1 is a schematic cross-sectional view of a laminate according to one embodiment. The laminate 100 includes a barrier layer 30 on one surface of a substrate 10 .

[0025] The substrate 10 is not particularly limited and may be a resin film, paper, or the like. Examples of resin films include polyester films such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); polyolefin films such as polyethylene and polypropylene; polystyrene films; polyamide films such as 66-nylon; polycarbonate films; and engineering plastic films such as polyacrylonitrile and polyimide films. Furthermore, the substrate may include a layer (film) selected from a homopolymer, a random copolymer, and a block copolymer. Furthermore, multiple layers of the same film may be laminated. From the perspective of achieving both oxygen barrier properties and water vapor barrier properties, PET is preferably used.

[0026] The resin film may be either stretched or unstretched. Alternatively, at least one stretched film and at least one unstretched film may be laminated. By including a film that is randomly stretched in biaxial directions, the substrate 10 can improve mechanical strength and dimensional stability. From the perspective of further improving oxygen barrier properties, a biaxially stretched polypropylene film is preferably used.

[0027] From the perspective of further improving water vapor barrier properties, a vapor-deposited film may be used as the resin film. A vapor-deposited film may be a film formed by pre-depositing a metal such as aluminum or a metal oxide such as aluminum oxide onto a substrate. Examples of vapor-deposited films include aluminum vapor-deposited films, aluminum oxide vapor-deposited films, and silicon dioxide vapor-deposited films, with aluminum vapor-deposited films being preferred.

[0028] The paper used for the substrate 10 is not particularly limited as long as it is a paper generally made of plant-derived pulp as a main component. Examples of paper include bleached and unbleached kraft paper, wood-free paper, cardboard, liner paper, coated paper, single gloss paper, glassine paper, and graphene paper.

[0029] The substrate 10 may be formed of one material alone or in combination of two or more materials. The substrate 10 may also be formed by laminating multiple layers of the same or different materials.

[0030] The thickness of substrate 10 is not particularly limited and may, for example, be between 3 μm and 200 μm, or between 6 μm and 30 μm. The thickness can be adjusted depending on the intended use or desired properties. Substrate 10 may contain at least one additive selected from fillers, antistatic agents, plasticizers, lubricants, and antioxidants. The surface of substrate 10 may be treated with at least one of chemical treatments, solvent treatments, corona treatments, plasma treatments, and ozone treatments.

[0031] The barrier layer 30 is formed from a barrier composition. The barrier composition includes a water-soluble polymer, at least one of a metal alkoxide and its hydrolyzate, and an inorganic layered compound. The inclusion of the inorganic layered compound in the barrier composition improves the oxygen barrier and water vapor barrier properties of the barrier layer 30 formed from the barrier composition. A laminate 100 having such a barrier layer 30 can exhibit high barrier properties even without a vapor-deposited thin film layer or multiple barrier layers on the substrate 10.

[0032] The mass ratio of the water-soluble polymer to the inorganic stratiform compound in the barrier composition is 0.3 to 3.0, preferably 0.5 to 2.5, and more preferably 0.7 to 2.0. When the mass ratio exceeds 3.0, the proportion of the inorganic stratiform compound decreases, thereby reducing the oxygen barrier properties and water vapor barrier properties of the barrier layer 30. On the other hand, when the mass ratio is less than 0.3, the proportion of the inorganic stratiform compound is excessive, resulting in turbidity in the barrier layer 30, impaired coating suitability, and increased thickness variation.

[0033] The inorganic layered compound in the barrier composition is an inorganic compound having a layered structure. Examples of inorganic layered compounds include clay minerals such as kaolin, smectite, and mica. Furthermore, the inorganic layered compound may be amorphous. The barrier composition may contain one of these compounds alone or a combination of two or more. The particle size of the inorganic layered compound is, for example, 0.1 μm to 10 μm. The aspect ratio of the inorganic layered compound is, for example, 50 to 5000.

[0034] From the viewpoint of further improving the oxygen barrier property and water vapor barrier property of the barrier layer 30 , the inorganic layered compound preferably includes montmorillonite or amorphous synthetic mica. From the viewpoint of improving the transparency of the laminate 100 , it more preferably includes amorphous synthetic mica.

[0035] Synthetic mica is highly compatible with water-soluble polymers and contains fewer impurities than natural mica. Therefore, when an inorganic layered compound contains synthetic mica, it can suppress the reduction in gas barrier properties and film cohesion caused by impurities. Furthermore, since synthetic mica contains fluorine atoms within its structure, it also helps to minimize the humidity dependence of the gas barrier properties of films formed with water-based coating agents. Because synthetic mica has a higher aspect ratio than other inorganic layered compounds, the labyrinth effect is more effectively exerted, particularly contributing to the high gas barrier properties of films formed with water-based coating agents.

[0036] The content of the inorganic stratiform compound in the barrier composition can be, for example, 15% to 30% by mass. From the perspective of further reducing the oxygen permeability and water vapor permeability of the barrier layer 30, the lower limit of the content of the inorganic stratiform compound in the barrier composition can be 20% by mass. From the perspective of further reducing the oxygen permeability and water vapor permeability of the barrier layer 30, the upper limit of the content of the inorganic stratiform compound in the barrier composition can be 25% by mass. It should be noted that the content of each component in the barrier composition is generally the same as the mixing ratio when preparing the raw material composition. Therefore, the content of each component can be calculated based on the mixing ratio. However, the content of each component can also be calculated using known analytical methods.

[0037] The water-soluble polymer is not particularly limited; examples include polyvinyl alcohol-based polymers, alcohol-based polymers such as starch / methylcellulose / carboxymethylcellulose, and acrylic polyol-based polymers. From the perspective of further improving oxygen barrier properties and water vapor barrier properties, the water-soluble polymer preferably includes a polyvinyl alcohol-based polymer. The polyvinyl alcohol-based polymer may be polyvinyl alcohol or a modified polyvinyl alcohol in which functional groups such as carboxyl and / or carbonyl groups have been introduced into polyvinyl alcohol. The number average molecular weight of the water-soluble polymer is, for example, from 40,000 to 180,000.

[0038] The degree of polymerization of polyvinyl alcohol and modified polyvinyl alcohol is preferably 1500 to 4200, more preferably 1700 to 3000. When the degree of polymerization of at least one of polyvinyl alcohol and modified polyvinyl alcohol is above the lower limit, the density of the barrier composition is improved, further enhancing the gas barrier properties of the barrier layer 30. When the degree of polymerization is below the upper limit, the dispersion of the barrier composition has an appropriate viscosity, improving coating properties. This improves the thickness uniformity of the barrier layer 30, further enhancing the gas barrier properties.

[0039] Polyvinyl alcohol-based water-soluble polymers can be obtained, for example, by saponifying (including partial saponification) polyvinyl acetate. These water-soluble polymers may contain several tens of percent or only a few percent of acetyl groups. Polyvinyl alcohol may also be completely saponified.

[0040] The content of the water-soluble polymer in the barrier composition is, for example, 15% to 35% by mass. To further reduce the oxygen permeability and water vapor permeability of the barrier layer 30, the lower limit of the water-soluble polymer content in the barrier composition may be 20% by mass. To further reduce the oxygen permeability and water vapor permeability of the barrier layer 30, the upper limit of the water-soluble polymer content in the barrier composition may be 30% or 25% by mass.

[0041] The combined mass ratio of the inorganic layered compound and the water-soluble polymer in the barrier composition is preferably 30% to 60% by mass, more preferably 35% to 55% by mass, and even more preferably 40% to 50% by mass. When the combined mass ratio of the inorganic layered compound and the water-soluble polymer in the barrier composition is within this range, the oxygen permeability and water vapor permeability of the barrier layer 30 can be further reduced.

[0042] Examples of the metal alkoxides and their hydrolyzates contained in the barrier composition include tetraethoxysilane [Si(OC2H5)4] and triisopropoxyaluminum [Al(OC3H7)3], which are represented by the general formula M(OR) n The metal alkoxides and their hydrolyzates represented by . These may be contained alone or in combination of two or more.

[0043] The total content of the metal alkoxide and its hydrolyzate in the barrier composition is, for example, 40% to 70% by mass. To further reduce the oxygen permeability and water vapor permeability of the barrier layer 30, the lower limit of the total content of the metal alkoxide and its hydrolyzate in the barrier composition may be 45% by mass. From the same perspective, the upper limit of the total content of the metal alkoxide and its hydrolyzate in the barrier composition may be 55% by mass. Including the metal alkoxide in the barrier composition improves the water and moisture resistance of the barrier layer 30. This reduces the humidity dependence of the barrier layer 30, thereby improving gas barrier properties.

[0044] The barrier composition may include at least one of a silane coupling agent and a hydrolyzate thereof. Examples of the silane coupling agent and its hydrolyzate include those having an organic functional group. Examples of such silane coupling agents and their hydrolyzates include ethyltrimethoxysilane, vinyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, and their hydrolyzates. Any one of these may be included alone, or in combination of two or more.

[0045] At least one of the silane coupling agent and its hydrolyzate preferably contains an epoxy group as an organic functional group. Examples of silane coupling agents containing epoxy groups include γ-glycidoxypropyltrimethoxysilane and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. The silane coupling agent containing epoxy groups and its hydrolyzate may contain organic functional groups other than epoxy groups, such as vinyl groups, amino groups, methacryloyl groups, or urea groups.

[0046] Silane coupling agents and their hydrolyzates, which have organic functional groups, can further enhance the oxygen and water vapor barrier properties of the barrier layer 30 through the interaction of their organic functional groups with the hydroxyl groups of the water-soluble polymer. In particular, the epoxy groups of the silane coupling agent and its hydrolyzate, combined with the hydroxyl groups of polyvinyl alcohol, can form a barrier layer 30 with particularly excellent oxygen and water vapor barrier properties. Furthermore, the inclusion of the silane coupling agent and its hydrolyzate improves the compatibility and dispersibility of the inorganic layered compound in the barrier composition forming the barrier layer 30. Consequently, the gas barrier properties of the barrier layer 30 can be further enhanced.

[0047] The total content of the silane coupling agent and its hydrolyzate in the barrier composition may be, for example, 15% by mass or less. From the perspective of further reducing the oxygen permeability and water vapor permeability of the barrier layer 30, the lower limit of the total content of the silane coupling agent and its hydrolyzate in the barrier composition may be 5% by mass, 3% by mass, or 1% by mass. From the same perspective, the upper limit of the total content of the silane coupling agent and its hydrolyzate in the barrier composition may be 10% by mass or 15% by mass.

[0048] The barrier layer 30 is formed by applying a dispersion containing a barrier composition and a dispersion medium onto the substrate 10 and drying the dispersion medium. The dispersion medium may include at least one selected from the group consisting of water, an alcohol, and an acid. The dispersion medium may contain from 10 to 20 parts by mass of water, from 3 to 10 parts by mass of alcohol, and from 0.1 to 1 part by mass of an acid per 1 part by mass of the barrier composition. The presence of an acid in the dispersion medium hydrolyzes the metal alkoxide contained in the barrier composition. The pH of the dispersion is preferably 4.1 or lower. The pH can be adjusted by the amount of acid added to the dispersion. A dispersion with a pH of 4.1 or lower is less likely to gel and has high coating suitability. The barrier layer 30 obtained by drying such a dispersion has low thickness variation and excellent thickness uniformity. To further improve the coating suitability of the dispersion, the pH of the dispersion may be 4.0 or lower, preferably 3.8 or lower, more preferably 3.5 or lower, and even more preferably 3.2 or lower. From the viewpoint of suppressing discoloration, the lower limit of pH may be, for example, 1.5 or 2.0. The pH is preferably 1.5 to 4.1, more preferably 1.5 to 4.0, and even more preferably 2.0 to 3.8.

[0049] The light transmittance of the dispersion at a wavelength of 350 nm to 800 nm may be 60% or higher. From the perspective of forming a more transparent barrier layer, it is preferably 65% or higher, and more preferably 70% or higher. The upper limit of the light transmittance may be, for example, 95% or 90%.

[0050] The thickness of the barrier layer 30 is not particularly limited, and can be, for example, from 0.1 μm to 3.0 μm. The thickness can be adjusted according to the intended use and required properties. The upper limit of the thickness of the barrier layer 30 can be 2.0 μm or 1.5 μm. When the thickness of the barrier layer 30 is within this range, the packaging bag using the laminate 100 can be made thinner.

[0051] The laminate 100 may include a base layer between the barrier layer 30 and the substrate 10. The base layer is a layer containing an organic polymer as a main component and is sometimes also referred to as a primer layer. The base layer between the barrier layer 30 and the substrate 10 can improve the adhesion between the barrier layer 30 and the substrate 10.

[0052] The content of the organic polymer in the base layer can be, for example, 70% by mass or more, or 80% by mass or more. Examples of the organic polymer include polyols having two or more hydroxyl groups at the polymer terminals, organosilane compounds such as silane coupling agents or hydrolyzates thereof, reaction products (water-based polyurethane resins) obtained by a two-liquid reaction of the above polyols with an isocyanate compound, reaction products of the above polyols with a silane coupling agent, polyethyleneimine, and polybutadiene. Any of these can be used alone or in combination.

[0053] Examples of polyols include at least one selected from acrylic polyols, polyvinyl acetals, polystyrene polyols, and polyurethane polyols. The acrylic polyol may be obtained by polymerizing an acrylic acid derivative monomer or by copolymerizing an acrylic acid derivative monomer with another monomer. Examples of acrylic acid derivative monomers include ethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxybutyl methacrylate. Examples of monomers copolymerized with acrylic acid derivative monomers include styrene.

[0054] The base layer can be formed by preparing a mixed solution by mixing the above-mentioned components in an organic solvent at any ratio, and applying the prepared mixed solution to one surface of the substrate 10. The mixed solution may contain, for example: a curing accelerator such as a tertiary amine, an imidazole derivative, a metal salt of a carboxylic acid, a quaternary ammonium salt, or a quaternary phosphonium salt; an antioxidant such as a phenolic, sulfur-based, or phosphite-based antioxidant; a leveling agent; a flow control agent; a catalyst; a cross-linking reaction accelerator; a filler, and the like.

[0055] The mixed liquid can be applied to the substrate 10 using a known printing method such as offset printing, gravure printing, or screen printing, or a known coating method such as roll coating, knife coating, or gravure coating. After coating, the mixed liquid can be heated to 50 to 200°C, dried, and / or cured, thereby forming a base layer on the substrate 10. When a base layer is formed on the substrate 10, the dispersion can be applied to the base layer to form the barrier layer 30. When no base layer is provided on the substrate 10, the dispersion can be applied to the substrate 10 to form the barrier layer 30.

[0056] The laminate 100 has excellent oxygen barrier properties. According to JIS K7126-2:2006, the oxygen permeability of the laminate measured by the mocon method (isobaric method) can be, for example, 2.0 ml / m 2 / day or less, or 1.0ml / m 2 / day or less, or 0.7ml / m 2 Note that the oxygen permeability in this specification is a value measured under the conditions of atmospheric pressure, 30° C., and 70% RH.

[0057] The laminate 100 has excellent water vapor barrier properties. According to JIS K 7129:2008, the water vapor permeability of the laminate measured by the mocon method (isobaric method) can be, for example, 10 g / m 2 / day or less, or 8.5g / m 2 / day or less, 5.0g / m 2 / day or less, or 4.0g / m 2 Note that the water vapor permeability in this specification is a value measured under the conditions of atmospheric pressure, 40° C., and 90% RH.

[0058] The oxygen permeability and water vapor permeability of the barrier layer 30 can be obtained by subtracting the measured values of the permeability of the substrate alone from the measured values of the permeability of the laminate 100. The oxygen permeability of the barrier layer 30 can be 2.0 ml / m 2 / day or less, or 1.0ml / m 2 / day or less, or 0.8ml / m 2 / day or less, or 0.7ml / m 2 The water vapor permeability of the barrier layer 30 can be, for example, 10.0 g / m 2 / day or less, or 7.0g / m 2 / day or less, 5.0g / m 2 / day or less, or 4.0g / m 2 / day or less. When the oxygen permeability and water vapor permeability of the barrier layer 30, obtained by subtracting the measured values of the permeability of the substrate alone from the measured values of the permeability of the laminate 100, are within this range, the oxygen barrier property and water vapor barrier property of the laminate 100 can be sufficiently improved regardless of the type of substrate.

[0059] One embodiment of a method for producing a laminate comprises the following steps: preparing a raw material composition comprising a water-soluble polymer, an inorganic layered compound, and at least one of a metal alkoxide and its hydrolyzate, wherein the mass ratio of the water-soluble polymer to the inorganic layered compound is 0.3 to 3.0; applying a dispersion comprising the raw material composition onto a substrate; and forming a barrier layer comprising the barrier composition from the dispersion by heating. The components and amounts of the raw material composition are as described in the laminate embodiment. Furthermore, during the step of preparing the raw material composition, at least one of a silane coupling agent and its hydrolyzate may be added to the raw material composition. The type and amount of the silane coupling agent and its hydrolyzate are also as described in the laminate embodiment.

[0060] The raw material composition is prepared by mixing the aforementioned components as raw materials. To simplify the preparation of the raw material composition, the water-soluble polymer and the inorganic layered compound can be premixed, and then the other components can be mixed. Alternatively, the metal alkoxide can be added while already hydrolyzed using a catalyst such as an acid.

[0061] The dispersion containing the raw material composition is obtained by mixing and dispersing the raw material composition prepared above in a dispersion medium. The dispersion medium may contain water, alcohol, and acid. The amounts of water, alcohol, and acid are as described above. The barrier layer can be formed by applying the prepared dispersion on the surface of the substrate and drying it. The pH of the dispersion containing the raw material composition during application is preferably 4.1 or less, more preferably less than 4.0. By having a pH of 4.1 or less or less than 4.0, gelation of the dispersion can be suppressed, making it easier to apply to the substrate. From the viewpoint of further suppressing the gelation of the dispersion, the pH of the dispersion containing the raw material composition (aqueous dispersion) is preferably 3.8 or less, more preferably 3.5 or less, and even more preferably 3.2 or less. The lower limit of the pH may be, for example, 1.5 or 2.0. The pH is preferably 1.5 or more and 4.1 or less, more preferably 1.5 or more and less than 4.0, and even more preferably 2.0 or more and 3.8 or less.

[0062] The dispersion containing the raw material composition may contain other components within a range that does not significantly impair the physical properties of the barrier layer. Examples of such components include dispersants, stabilizers, viscosity modifiers, and colorants.

[0063] The pH of the dispersion containing the raw material composition can be adjusted using either an organic acid or an inorganic acid. For example, hydrochloric acid, acetic acid, sulfuric acid, nitric acid, etc. can be used. These acids can be diluted with water and / or ethanol before use.

[0064] The dispersion containing the raw material composition can be applied to the substrate using known printing methods such as offset printing, gravure printing, or screen printing, or known coating methods such as roll coating, knife edge coating, or gravure coating. After coating, the barrier layer can be formed by drying and / or curing the dispersion, for example, by heating to approximately 100°C. If an underlayer is already present on the substrate, the barrier layer can also be formed on the underlayer using the same method as described above.

[0065] The laminate produced by this method has excellent oxygen and water vapor barrier properties. That is, even without a vapor-deposited thin film layer composed of an inorganic oxide, etc., it can still have excellent oxygen and water vapor barrier properties. Therefore, compared to laminates with vapor-deposited thin film layers composed of an inorganic oxide, etc., the laminate can be produced at a lower manufacturing cost. Such a laminate is suitable for use as a laminate film constituting packaging bags for storing contents.

[0066] Figure 2 This is a plan view showing an embodiment of a packaging bag formed using a laminate. The packaging bag 200 includes: a sealing portion 211 formed by pasting the peripheral edges of a pair of roughly rectangular laminates 100, and a storage portion 218 formed between the pair of laminates 100, 100 by the sealing portion 211. That is, the side end portion 214, the lower end portion 216, and the upper end portion 217 of the packaging bag 200 are sealed by the sealing portion 211. The packaging bag 200 includes a storage portion 218 for storing food and other contents in the non-sealed portion 215 surrounded by the sealing portion 211. Food and other contents are enclosed in the storage portion 218. It should be noted that the sealing portion 211 at the lower end portion 216 can be sealed after the contents are filled into the storage portion 218.

[0067] The pair of laminates 100 are stacked so that the barrier layers 30 face each other. The pair of laminates 100 can be bonded together at the seal portion 211 using an adhesive. Alternatively, the pair of laminates 100 can be bonded together by bonding heat seal layers provided on the barrier layers 30 to form the seal portion 211.

[0068] Since the laminate 100 has excellent oxygen barrier properties or water vapor barrier properties, it is possible to sufficiently suppress degradation of the contents contained in the container 218 due to the oxygen or water vapor barrier properties.

[0069] The following describes the steps for manufacturing a packaging bag 200 (package) using the laminate 100. A pair of laminates 100 are prepared. In the case of the laminates 100, the barrier layers 30 of the laminates 100, or the heat-seal layers provided on the barrier layers 30, are positioned facing each other and bonded together with a resealable element 230 (e.g., a zipper tape) sandwiched therebetween. This forms a sealed portion 211 at positions corresponding to the upper end 217 and the side ends 214, 214. The sealed portion 211 forms a U-shaped, enclosed, unsealed portion 215.

[0070] After the sealing portion 211 is formed, the opening unit 220 can be formed. For example, easy-opening processing portions 224, 224 consisting of a scar group are formed at the side end portions 214, 214. The easy-opening processing portion 224 is not limited to the scar group, and can also be a V-shaped, U-shaped, or I-shaped cut. In addition, a half-cut line 221 that serves as a track disconnected from the easy-opening processing portion 224 can also be formed on the surface portion of the laminate 100 between the upper end portion 217 and the resealing unit 230. The half-cut line 221 can be formed using a laser. After the opening unit 220 is formed, the sealing portion 211 is cut and the edges are trimmed to separate the packaging bags.

[0071] Next, the contents are filled from the unsealed lower end 216. The laminated bodies 100 are then bonded together at the lower end 216, thereby also forming a sealed portion 211 at the lower end 216. In this manner, the packaging bag 200 and the packaging body can be manufactured. The half-cut line can also be formed before the bonded pair of laminated bodies 100 are cut to a predetermined width.

[0072] The packaging bag 200 includes an opening unit 220 located above the unsealed portion 215, which is used to cut and unseal the packaging bag 200 by traversing the side ends 214, 214, and the middle thereof; and a resealing unit 230 located below the opening unit 220, which is used to reseal the container 218 after being unsealed by the opening unit 220. The resealing unit 230 can employ a known structure that allows for repeated unsealing and sealing. For example, it can be a synthetic resin fastener that allows for repeated sealing by engaging a strip-shaped protrusion with a strip-shaped groove, or an adhesive sealant.

[0073] The package includes a packaging bag 200 and contents contained in a container 218 of the packaging bag 200. The contents are not particularly limited, and examples thereof include food, pharmaceuticals, electronic components, and electronic devices. The packaging bag 200 prevents the contents from being altered or degraded by oxygen and water vapor.

[0074] Several embodiments of the present disclosure have been described above, but the present disclosure is not limited to the aforementioned embodiments. For example, the laminate 100 may include any layer or film between the substrate 10 and the base layer, and between the base layer and the barrier layer 30, as long as the functionality of the laminate is not significantly impaired. The shape of the packaging bag 200 and the packaging body is not limited to a four-sided bag. For example, it may be a two-sided bag, a three-sided bag, a flap bag, or a stand-up bag with a bottom tape.

[0075] This disclosure includes the following contents.

[0076] [1] A laminate having a barrier layer formed from a barrier composition on a substrate, the barrier composition comprising a water-soluble polymer, an inorganic layered compound, and at least one of a metal alkoxide and a hydrolyzate thereof, wherein the mass ratio of the water-soluble polymer to the inorganic layered compound in the barrier composition is 0.3 to 3.0.

[0077] [2] The laminate according to [1], wherein the barrier layer contains at least one of a silane coupling agent and a hydrolyzate thereof.

[0078] [3] The laminate according to [2], wherein at least one of the silane coupling agent and its hydrolyzate has an epoxy group.

[0079] [4] The laminate according to any one of [1] to [3], wherein the barrier layer is obtained by drying a dispersion containing the barrier composition and having a pH of less than 4.0.

[0080] [5] The laminate according to any one of [1] to [4], wherein the total mass ratio of the water-soluble polymer and the mass ratio of the inorganic layered compound in the barrier composition is 30 to 60 mass %.

[0081] [6] The laminate according to any one of [1] to [5], wherein the barrier layer has a thickness of 0.1 to 3.0 μm.

[0082] [7] The laminate according to any one of [1] to [6], wherein the water-soluble polymer comprises at least one of polyvinyl alcohol and modified polyvinyl alcohol.

[0083] [8] The laminate according to [7], wherein the degree of polymerization of at least one of the polyvinyl alcohol and the modified polyvinyl alcohol is 1500 to 3000.

[0084] [9] The laminate according to any one of [1] to [8], wherein the water vapor permeability of the barrier layer is 10.0 g / m 2 / day or less.

[0085]

[10] The laminate according to any one of [1] to [9], wherein the oxygen permeability of the barrier layer is 2.0 mL / m 2 / day or less.

[0086]

[11] A packaging bag comprising the laminate according to any one of [1] to

[10] .

[0087]

[12] A packaging body comprising the packaging bag according to

[11] above and a content contained in a containing portion of the packaging bag.

[0088]

[13] A method for manufacturing a laminate, comprising: a step of preparing a raw material composition, wherein the raw material composition contains a water-soluble polymer, an inorganic layered compound, and at least one of a metal alkoxide and a hydrolyzate thereof, and the mass ratio of the water-soluble polymer to the inorganic layered compound is 0.3 to 3.0; a step of applying a dispersion containing the raw material composition on a substrate; and a step of forming a barrier layer formed of a barrier composition from the dispersion by heating.

[0089]

[14] The method for producing a laminate according to

[13] , wherein the pH of the dispersion liquid is less than 4.0.

[0090] Example

[0091] Hereinafter, the present disclosure will be described in more detail with reference to Examples and Comparative Examples. However, the present disclosure is not limited to the following Examples.

[0092] [Production and Evaluation of Laminated Products]

[0093] (Example 1)

[0094] 0.379 g of polyvinyl alcohol (PVA, manufactured by Japan VAM & POVAL Co., Ltd., trade name: JF-17, degree of polymerization: 1700, fully saponified) and 3.692 g of water-swellable synthetic mica (MEB, manufactured by Co-op Chemical Co., Ltd., trade name: Somasif MEB-3) were mixed with a mixed solvent of water and methanol (water:methanol = 90:10 (weight ratio)) to prepare a water / methanol dispersion. 0.209 g of γ-glycidoxypropyltrimethoxysilane (KBM403) was added to the prepared water / methanol dispersion and stirred. Next, hydrochloric acid of a specified concentration was added to the water / methanol solution containing 2.453 g of tetraethoxysilane (TEOS) to hydrolyze the TEOS. 14.791 g of a water / methanol solution containing hydrolyzed TEOS was added to the water / methanol dispersion to prepare a dispersion containing the raw material composition (hereinafter referred to as the "dispersion"). The mass ratios of the non-volatile components (PVA, MEB, TEOS, and KBM403) contained in this dispersion (calculated based on the blending ratio during dispersion preparation) are shown in Table 1 as the composition of the barrier composition. The solids concentration in the dispersion is also shown in Table 1, and the pH of the dispersion is shown in Table 2.

[0095] The concentrations of PVA, MEB, TEOS, and KBM403 contained in the barrier composition were 24 mass%, 16 mass%, 50 mass%, and 10 mass%, respectively. Therefore, the mass ratio (P / M) of the water-soluble polymer (P) to the inorganic layered compound (M) was 1.5, as shown in Table 2. Furthermore, the combined mass ratio of the water-soluble polymer and the inorganic layered compound to the total barrier composition (PM / total) was 40 mass%, as shown in Table 2.

[0096] The prepared dispersion was applied to a polyethylene terephthalate (PET) film (thickness: 12 μm) as a substrate using a bar coating method. After application, the film was dried by heating to form a barrier layer on the PET film. This produced the laminate of Example 1. The thickness of the barrier layer was 1.0 μm to 1.3 μm. Furthermore, the thickness of the laminate was 13.0 μm to 13.5 μm.

[0097] The oxygen permeability of the resulting laminate was measured using an oxygen permeability meter (MOCON, OXTRAN 2 / 21). The measurement atmosphere was set to 30°C and 70% RH. Separately, the water vapor permeability was measured using a water vapor permeability meter (MOCON, PERMARTRAN 3 / 31). The measurement atmosphere was set to 40°C and 90% RH. The results of each measurement are shown in Table 2.

[0098] (Examples 2 to 8, Comparative Example 1)

[0099] A laminate was prepared in the same manner as in Example 1, except that the composition of the barrier composition and the pH of the dispersion were changed as shown in Tables 1 and 2. The oxygen permeability and water vapor permeability were measured. The results are shown in Table 2.

[0100] [Table 1]

[0101]

[0102] [Table 2]

[0103]

[0104] Examples 1 to 8, in which P / M is 0.3 or more and 3.0 or less, have lower water vapor permeabilities than Comparative Example 1 and exhibit high water vapor barrier properties.

[0105] (Comparative Example 2)

[0106] A laminate was produced in the same manner as in Example 1, except that montmorillonite (Mon.) was used instead of synthetic mica, and the composition of the barrier composition and the pH of the dispersion were adjusted as shown in Tables 3 and 4. The oxygen and water vapor permeabilities were measured. The results are shown in Table 4.

[0107] (Comparative Example 3)

[0108] A dispersion was prepared in the same manner as in Example 1, using montmorillonite (Mon.) instead of synthetic mica, and adjusting the barrier composition composition and the pH of the dispersion as shown in Tables 3 and 4. A mixed material containing silica was evaporated onto the same PET film as used in Example 1 using a vacuum evaporation apparatus employing electron beam heating, thereby forming a 20 nm thick deposited thin film layer composed of silica on the PET film. A barrier layer was then formed on the deposited thin film layer on the substrate in the same manner as in Example 1, thereby producing the laminate of Comparative Example 3. The oxygen and water vapor permeabilities were measured in the same manner as in Example 1, and the results are shown in Table 4.

[0109] [Table 3]

[0110]

[0111] [Table 4]

[0112]

[0113] In Comparative Example 2, which used montmorillonite as the inorganic layered compound and adjusted the P / M ratio to the same high value as Comparative Example 1 in Tables 1 and 2, the water vapor barrier properties were low, similar to Comparative Example 1. Therefore, it was confirmed that, regardless of the type of inorganic layered compound, when the P / M ratio was high, the laminate did not have water vapor barrier properties. In Comparative Example 3, in which a metal thin film was vapor-deposited on the substrate of Comparative Example 2 to form a vapor-deposited thin film layer in order to impart barrier properties to oxygen and water vapor, the vapor-deposited thin film layer improved the gas barrier properties, and in particular, the water vapor barrier properties were significantly improved. Therefore, it was confirmed that, when the P / M ratio was high, a vapor-deposited thin film layer was required to ensure water vapor barrier properties. On the other hand, if the P / M ratio was lowered as in Examples 1 to 8, the water vapor barrier properties could be improved even without providing a vapor-deposited thin film layer.

[0114] (Example 9 to Example 15)

[0115] A laminate was prepared in the same manner as in Example 1, except that the composition of the barrier composition and the pH of the dispersion were adjusted as shown in Tables 5 and 6. The oxygen and water vapor permeabilities were measured. Furthermore, after preparation, the dispersion was exposed to air, and the time it took for the dispersion to gel was measured. The results are shown in Table 6. The time it took for the dispersion used in Comparative Example 3 to gel was also measured.

[0116] [Table 5]

[0117]

[0118] [Table 6]

[0119]

[0120] The dispersion in Comparative Example 3 did not gel for over a week. Meanwhile, the longest gelation time for the Examples shown in Tables 5 and 6 was 48 hours. This indicates that gelation is facilitated when the pH / M ratio is lowered. As shown in Table 6, the gelation time for Examples 9 and 10, which had a pH of 4.1, was relatively short. This confirms that lowering the pH of the dispersion can suppress gelation, allowing for smoother application of the dispersion to a substrate.

[0121] (Example 16)

[0122] The material formed into a base layer on a biaxially stretched polypropylene film (OPP film) is used as a substrate. Specifically, 3-isocyanatepropyltrimethoxysilane, acrylic polyol, and aliphatic isocyanate are mixed in a diluent (ethyl acetate) at a specified mass ratio to prepare a mixed solution (solid content: 2% by mass) for base layer formation. The mixed solution is applied to one surface of the OPP film by a gravure coating method. After coating, it is dried to form a base layer on one surface of the OPP. It should be noted that the OPP film uses a commercially available product (AJ PlastPublic Co. system, trade name: PJ201, thickness: 20 μm) consisting of a homopolymer polypropylene film and a copolymer polypropylene film.

[0123] After forming a base layer on an OPP film, a barrier layer was formed on the substrate using the same method as in Example 1, except that a barrier composition having the composition shown in Table 7 and the pH of the dispersion was adjusted to the value shown in Table 8. Evaluation films were prepared using the same method as in Example 1, and the oxygen and water vapor permeabilities were measured. The results are shown in Table 8.

[0124] (Comparative Example 4)

[0125] A base layer formed on an OPP film using the same method as in Example 16 was used as the substrate. A barrier layer was formed on the substrate using the same method as in Example 1, except that a barrier composition having the composition shown in Table 7 was used and the pH of the dispersion was adjusted to the value shown in Table 8. Evaluation films were prepared using the same method as in Example 1, and the oxygen and water vapor permeabilities were measured. The results are shown in Table 8.

[0126] (Examples 17 to 19, Comparative Example 5)

[0127] A laminate and evaluation film were prepared in the same manner as in Example 1, except that the substrate was an aluminum vapor-deposited barrier film (VMCPP film), the composition of the barrier composition was as shown in Table 7, and the pH of the dispersion was adjusted as shown in Table 8. The oxygen and water vapor permeabilities were measured. The results are shown in Table 8. A commercially available VMCPP film (manufactured by Toray Advanced Film Co., Ltd., trade name: VM-CPP2703, thickness: 20 μm) was used.

[0128] [Table 7]

[0129]

[0130] [Table 8]

[0131]

[0132] Even when a substrate including a base layer was used, water vapor barrier properties were not improved in Comparative Example 4, where P / M was larger than that in Example 16. On the other hand, even when a base layer was formed on the substrate, oxygen barrier properties and water vapor barrier properties were improved in Example 16, where P / M was smaller than that in Comparative Example 4. This indicates that the P / M value affects gas barrier properties regardless of the presence or absence of a base layer.

[0133] When using a VMCPP film as the substrate, even Comparative Example 5, which has a higher P / M ratio than Examples 17-19, exhibits high barrier properties against oxygen and water vapor. Examples 17-19, which have a lower P / M ratio than Comparative Example 5, further improve gas barrier properties, with all examples showing particularly high water vapor barrier properties. This demonstrates that, regardless of the substrate type, a barrier layer with a lower P / M ratio improves gas barrier properties.

[0134] (Example 20 to Example 22)

[0135] PVA with a degree of polymerization of 2400 (manufactured by Kuraray Co., Ltd., trade name: PVA-124, fully saponified type) and PVA with a degree of polymerization of 4000 (manufactured by Japan VAM & POVAL Co., Ltd., trade name: JC-40, fully saponified type) were prepared. Laminated products were prepared in the same manner as in Example 1, except that the PVAs having the degrees of polymerization shown in Table 9 were used and the barrier composition had the same composition as shown in Table 9. The oxygen and water vapor permeabilities were measured. The results are shown in Table 10.

[0136] [Table 9]

[0137]

[0138] [Table 10]

[0139]

[0140] Comparison of the gas barrier properties of laminates using multiple PVAs with varying degrees of polymerization revealed that the laminate with a degree of polymerization of 2400 exhibited the highest gas barrier properties. Meanwhile, the laminate with a PVA degree of polymerization of 4000 exhibited lower gas barrier properties than the laminates with degrees of polymerization of 1700 and 2400.

[0141] (Comparative Example 6, Example 23)

[0142] A laminate was prepared in the same manner as in Example 1, except that the composition of the barrier composition was as shown in Table 11. The oxygen permeability and water vapor permeability were measured. The results are shown in Table 12.

[0143] [Table 11]

[0144]

[0145] [Table 12]

[0146]

[0147] Example 23 and Comparative Example 6 have the same P / M value, but Comparative Example 6 does not contain TEOS as a metal alkoxide. Comparing the gas barrier properties of Example 23 and Comparative Example 6, Example 23 exhibits superior gas barrier properties. These results confirm that the addition of a metal alkoxide can improve the gas barrier properties of the laminate.

[0148] (Example 24)

[0149] A laminate was produced in the same manner as in Example 1, except that the composition of the barrier composition was as shown in Table 13. The oxygen and water vapor permeabilities were measured. The results are shown in Table 14. For comparison, Tables 13 and 14 also show the results of Examples 3 and 4.

[0150] [Table 13]

[0151]

[0152] [Table 14]

[0153]

[0154] The P / M value of Example 24 is the same as that of Examples 3 and 4, but Example 24 does not contain KBM403 as a silane coupling agent. Comparing the gas barrier properties of Example 24 with those of Examples 3 and 4, Examples 3 and 4 exhibit excellent gas barrier properties. These results confirm that the addition of a silane coupling agent can further improve the gas barrier properties of the laminate.

[0155] [Calculation of gas permeability of barrier layer alone]

[0156] In each of the Examples and Comparative Examples, the gas permeability of the barrier layer alone was determined. The results are shown in Table 15. The gas permeability of the barrier layer alone was determined using the following formula using the gas permeability of the laminate measured in the Examples above and the measured gas permeability of the substrate alone. The measured gas permeability of the substrate alone was determined using the same method as that used to determine the measured gas permeability of the laminate.

[0157] 1 / P total =1 / P film +1 / P base

[0158] Ptotal : Gas permeability of laminate (measured value)

[0159] P film : Gas permeability of the barrier layer alone

[0160] P base : Gas permeability of substrate alone (measured values) [Table 15]

[0161]

[0162] The gas permeability of the barrier layer alone was determined by subtracting the measured values for the laminate and the substrate alone. In each example, the gas permeability of the barrier layer alone was slightly higher than that of the laminate for both oxygen and water vapor. Therefore, it can be assumed that the gas barrier properties of the barrier layer alone are equivalent to those of the laminate.

[0163] [Measurement of light transmittance of dispersion liquid]

[0164] The light transmittance of the dispersions prepared in Examples 1, 3, 8, 10, and Comparative Example 2 was measured. The transmittance was measured using a spectrophotometer (manufactured by Hitachi High-Technologies Corporation, trade name: U-3010) to measure the transmittance of light in the wavelength range of 200 nm to 800 nm. The results are shown in FIG. Figure 3 As shown. In Example 1, Example 3 and Example 8 in which synthetic mica is used as the inorganic layered compound, a tendency for the light transmittance to increase is found compared to Comparative Example 2 in which montmorillonite is used. In addition, although the P / M of Example 1, Example 3 and Example 8 is larger than that of Comparative Example 2 and the proportion of the inorganic layered compound in the dispersion is higher, Example 1, Example 3 and Example 8 show a higher light transmittance than Comparative Example 2. Therefore, it can be considered that by containing synthetic mica in the inorganic layered compound, a laminate with high light transmittance and transparency can be produced even when the barrier layer contains a large amount of inorganic layered compound. On the other hand, it can be considered that since Example 10 takes a short time to gelation and is easy to gel, the light transmittance is lower than that of Example 1, Example 3 and Example 8, and becomes the same as that of Comparative Example 2.

[0165] Industrial Applicability

[0166] The present disclosure can provide a laminate having high oxygen barrier properties and water vapor barrier properties, and a method for producing the same, as well as a packaging bag and a packaging body using the laminate.

[0167] Explanation of symbols

[0168] 10…substrate, 30…barrier layer, 100…laminate, 200…packaging bag, 211…sealed portion, 214…side end portion, 215…unsealed portion, 216…lower end portion, 217…upper end portion, 218…accommodating portion, 220…opening unit, 221…half-cut line, 224…easy-opening portion, 230…resealing unit.

Claims

1. A laminate comprising a substrate and a barrier layer formed from a barrier composition, The barrier composition comprises at least one of a water-soluble polymer, an inorganic layered compound, and a metal alkoxide and a hydrolyzate thereof. The mass ratio of the water-soluble polymer to the inorganic layered compound in the barrier composition is 0.3 to 3.

0.

2. The laminate according to claim 1, wherein The barrier layer includes at least one of a silane coupling agent and a hydrolyzate thereof.

3. The laminate according to claim 2, wherein At least one of the silane coupling agent and a hydrolyzate thereof has an epoxy group.

4. The laminate according to claim 1, wherein The barrier layer is obtained by drying a dispersion containing the barrier composition and having a pH of 4.1 or less.

5. The laminate according to claim 1, wherein The total of the mass ratio of the water-soluble polymer and the mass ratio of the inorganic layered compound in the barrier composition is 30% by mass or more and 60% by mass or less. The laminate according to claim 1 , wherein: The barrier layer has a thickness of 0.1 μm to 3.0 μm.

7. The laminate according to claim 1, wherein The water-soluble polymer includes at least one of polyvinyl alcohol and modified polyvinyl alcohol.

8. The laminate according to claim 7, wherein The degree of polymerization of at least one of the polyvinyl alcohol and the modified polyvinyl alcohol is 1500 or more and 4200 or less.

9. The laminate according to claim 1, wherein The water vapor permeability of the barrier layer is 10.0 g / m 2 / day or less.

10. The laminate according to claim 1, wherein The oxygen permeability of the barrier layer is 2.0 mL / m 2 / day or less. 11 . A packaging bag comprising the laminate according to claim 1 . 12 . A package comprising the packaging bag according to claim 11 and a content contained in a storage portion of the packaging bag.

13. A method for manufacturing a laminate, comprising: A step of preparing a raw material composition, wherein the raw material composition comprises a water-soluble polymer, an inorganic layered compound, and at least one of a metal alkoxide and a hydrolyzate thereof, wherein the mass ratio of the water-soluble polymer to the inorganic layered compound is 0.3 to 3.0; A step of applying a dispersion containing the raw material composition onto a substrate; and A step of forming a barrier layer composed of the barrier composition from the dispersion by heating.

14. The method for producing a laminate according to claim 13, wherein: The pH of the dispersion is 4.1 or less.

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