Barrier laminate, package, and method for producing barrier laminate

Abstract

Provided is a barrier laminate in which deterioration of barrier properties due to stress is effectively suppressed, and the barrier laminate is excellent in recyclability. A barrier laminate 1 comprises a paper substrate 10, an adhesive layer 20, a barrier layer 30, and a heat seal layer 40 in the stated order in the thickness direction, the adhesive layer 20 being a cured product of a water-disintegrable adhesive containing at least a water-suspendable polymer, and the barrier laminate 1 having Martens hardness HM of 5 MPa or less and a restoration rate of 20% or more.

Description

Barrier laminate, packaging, and method for manufacturing a barrier laminate

[0001] This disclosure relates to barrier laminates, packaging materials, and methods for manufacturing barrier laminates.

[0002] In recent years, the environmental problem caused by microplastics has been widely discussed. Even in paper-based products, there is a growing demand to improve recyclability by constructing products using as much paper as possible to reduce the environmental impact.

[0003] Conventionally, packaging materials with high gas barrier properties have been used to suppress the deterioration of the quality of contents (e.g., food, pharmaceuticals, chemical products, and cosmetics) due to moisture or oxygen. In this context, packaging materials with a paper base, considering the recycling or incineration of used packaging materials, are attracting attention. However, paper bases generally have insufficient gas barrier properties. Therefore, to improve the gas barrier properties of packaging materials with a paper base, methods such as coating the paper base with resin or laminating a resin film with an inorganic vapor-deposited film onto the paper base are being considered.

[0004] Patent Document 1 discloses a laminate in which a gas barrier thin film layer is laminated by plasma polymerization onto a substrate made of paper or pulp mold having a sealing layer on its surface made of a polycondensate of polysaccharides and silicon compounds. In Patent Document 1, since the substrate made of paper or pulp mold is placed inside the plasma polymerization apparatus when forming the gas barrier thin film layer, paper dust or pulp dust generated from the paper or pulp mold tends to hinder the reduction of pressure inside the plasma polymerization apparatus to a pressure suitable for plasma polymerization. Therefore, it is difficult to form a thin film layer with stable gas barrier properties, the adhesion between the sealing layer and the thin film layer tends to be insufficient, and the gas barrier properties tend to be unstable. Patent Document 1 relates to chemical vapor deposition for the formation of a gas barrier thin film layer, but similar problems exist in physical vapor deposition as well.

[0005] Patent No. 4622201

[0006] In barrier laminates using paper substrates, further improvements in recyclability are desired by increasing the pulp recovery rate after redisintegration.

[0007] Our research has revealed that when stress such as bending load is applied to a barrier laminate, which is formed by laminating a barrier layer on the surface of a paper substrate via an adhesive layer, the adhesive layer in the barrier laminate peels off due to the stress, and the barrier properties of the barrier laminate decrease.

[0008] This disclosure aims to provide a barrier laminate comprising a paper substrate, a barrier layer, and a heat-seal layer, which effectively suppresses the deterioration of barrier properties due to stress such as bending loads, and further provides a barrier laminate with excellent recyclability.

[0009] The inventors of the present invention have conducted diligent studies to solve the above problems and have found that the problems can be solved by using a cured product of a water-soluble adhesive containing a water-suspendable polymer as the adhesive layer interposed between the paper substrate and the barrier layer, and by controlling the Martens hardness and recovery rate of the adhesive layer to a predetermined range, thereby completing the present invention. Specifically, the present invention provides the following.

[0010] (1) A barrier laminate comprising a paper substrate, an adhesive layer, a barrier layer, and a heat seal layer in this order in the thickness direction, wherein the adhesive layer is a cured product of a hydrolyzable adhesive containing at least a water-suspendable polymer, has a Martens hardness HM of 5 MPa or less, and has a recovery rate of 20% or more.

[0011] (2) The amount of solids in the adhesive layer to be applied is 6 g / m² ２ The barrier laminate described in (1) below.

[0012] (3) The barrier laminate according to (1), wherein the adhesive layer contains an EVA resin.

[0013] (4) The barrier laminate according to (1), wherein the pulp recovery rate of the paper substrate in accordance with the disintegration method of JIS P8220:2012 is 80% by mass or more.

[0014] (5) A packaging body in which contents are packaged using a barrier laminate as described in any one of (1) to (4), wherein at least a portion of the peripheral edge of the barrier laminate is heat-sealed with the heat-seal layers facing each other to seal the contents.

[0015] (6) A packaging body in which contents are packaged using a barrier laminate described in any one of (1) to (4), wherein a second heat seal layer identical or different from the heat seal layer is laminated on the paper substrate of the barrier laminate, and the contents are sealed by overlapping and heat sealing the heat seal layer and the second heat seal layer at least a part of the peripheral edge of the barrier laminate.

[0016] According to this disclosure, a barrier laminate comprising a paper substrate, a barrier layer, and a heat-seal layer can be provided that effectively suppresses the deterioration of barrier properties due to stress such as bending loads, and further provides a barrier laminate with excellent recyclability.

[0017] This is a cross-sectional view showing an example of the layer structure of the transfer film of this disclosure. This is a cross-sectional view showing an example of the layer structure of the transfer film of this disclosure. This is a cross-sectional view showing an example of the layer structure of the barrier laminate of this disclosure. This is a cross-sectional view showing an example of the layer structure of the barrier laminate of this disclosure. This is a process diagram showing an example of how to manufacture the barrier paper of this disclosure. This is a process diagram showing an example of how to manufacture the barrier paper of this disclosure. This is a process diagram showing an example of how to manufacture the barrier paper of this disclosure. This is a diagram showing an embodiment of a package formed using a barrier laminate. This is a diagram showing an embodiment of a package formed using a barrier laminate. This is a diagram showing an embodiment of a package formed using a barrier laminate. This is a diagram showing an embodiment of a package formed using a barrier laminate.

[0018] The embodiments of this disclosure will be described below with reference to the drawings and other illustrations. This disclosure can be implemented in many different forms and should not be construed as being limited to the embodiments described below.

[0019] Drawings may schematically represent the width, thickness, angles, and shape of each part compared to the actual form, in order to clarify the explanation. However, drawings are merely examples and do not limit the interpretation of this disclosure. In this specification and each drawing, elements similar to those described in previously shown drawings are denoted by the same reference numerals, and detailed explanations may be omitted as appropriate. For the sake of explanation, terms such as "up" or "down" may be used, but the vertical direction may be reversed. The same applies to the horizontal direction.

[0020] In the following description, each component (for example, additives, resin components such as various resins, colorants, and hardeners) can be used individually or in combination of two or more types.

[0021] [Transfer Film] First, the configuration of the transfer film used in the manufacture of the barrier laminate of this disclosure will be described. The transfer film used in the manufacture of the barrier laminate of this disclosure comprises a support substrate, a heat seal layer, and a barrier layer in this order in the thickness direction. The transfer film may further include an anchor coat layer between the heat seal layer and the barrier layer. The heat seal layer, the anchor coat layer if necessary, and the barrier layer constitute the transfer layer. In one embodiment, the transfer film and transfer layer may further include a functional layer such as a protective layer. In this specification, "laminated in this order" means not only that each layer is directly laminated without interposing other layers, but also that each layer is laminated indirectly via other layers.

[0022] In other words, the transfer film comprises a support substrate and a transfer layer provided on the support substrate, wherein the transfer layer comprises a heat seal layer and a barrier layer in this order in the thickness direction. In one embodiment, the transfer layer may further include an anchor coat layer between the heat seal layer and the barrier layer. The heat seal layer is in contact with the support substrate and is provided so as to be removable from the support substrate.

[0023] In this case, the transfer layer is either in contact with the barrier layer and the heat seal layer (or the anchor coat layer if an anchor coat layer is provided), or the transfer layer does not have a release layer between the barrier layer and the heat seal layer.

[0024] In one embodiment, the transfer film comprises a protective layer on a barrier layer. In one embodiment, if the barrier layer is composed of metal oxides such as aluminum oxide and silicon oxide, the transfer film may also comprise a barrier coating layer on the barrier layer.

[0025] The support substrate used as the transfer substrate, and therefore the transfer film, may be a single-sheet film or a continuous film wound into a roll.

[0026] Figure 1 shows one embodiment of a transfer film used in the manufacture of the barrier laminate of the present disclosure. The transfer film 2 in Figure 1 comprises a support substrate 50, a heat seal layer 40, and a barrier layer 30 in this order in the thickness direction.

[0027] Figure 2 shows another embodiment of the transfer film used in the manufacture of the barrier laminate of this disclosure. The transfer film 2 in Figure 2 comprises a support substrate 50, a heat seal layer 40, an anchor coat layer 32, and a barrier layer 30 in this order in the thickness direction.

[0028] <Support Substrate> The transfer film 2 is equipped with a support substrate as a transfer substrate. A film made of resin (hereinafter also referred to as "resin film") is preferred as the support substrate. Examples of the above resins include polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); polyamides such as various nylons, especially aromatic polyamides such as nylon MXD6; vinyl resins such as ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer and polyvinyl alcohol; polyolefins such as polyethylene, polypropylene, polybutene and cyclic polyolefins; styrene-based resins such as styrene homopolymer, acrylonitrile-styrene copolymer (AS resin), and acrylonitrile-butadiene-styrene copolymer (ABS resin); (meth)acrylic resin, polycarbonate, polyimide, diallyl phthalate resin, silicone resin, polysulfone resin, polyphenylene sulfide resin, polyethersulfone resin, polyurethane, cellulose resin, and fluororesin.

[0029] The resin film may consist of a single layer, or it may consist of two or more layers of the same or different compositions. The resin film may be an unstretched film, or a stretched film such as a uniaxially oriented film or a biaxially oriented film.

[0030] The thickness of the support substrate 50 is preferably 5 μm to 200 μm, more preferably 8 μm to 100 μm, and even more preferably 10 μm to 80 μm.

[0031] The support substrate 50 preferably has the property of being able to form a heat seal layer on the substrate and being able to be easily peeled off the substrate from the heat seal layer in the peeling process. From this viewpoint, among resin films, polyester film, polyethylene film, polypropylene film and polyamide film are preferred, polyester film is more preferred, and polyethylene terephthalate film is even more preferred.

[0032] The support substrate 50 has excellent mechanical, physical, and chemical properties that can withstand the barrier layer formation process, and it is particularly preferable that it has strength and heat resistance. Polyethylene terephthalate film is also preferable from this viewpoint.

[0033] Preferably, the resin film does not have a known easy-adhesion treatment applied to the surface in contact with the heat-seal layer, and it is also preferable that no known easy-adhesion layer is provided on the surface in contact with the heat-seal layer. With such a configuration, for example, the peelability between the support substrate and the heat-seal layer in the peeling process can be improved.

[0034] Furthermore, the surface of the support substrate 50 that contacts the heat seal layer 40 may be provided with a fine uneven surface to achieve a predetermined surface roughness (for example, Ra of 0.5 μm or more and 10 μm or less). This allows the fine uneven surface corresponding to the fine uneven surface of the support substrate 50 to be transferred and formed on the exposed surface of the heat seal layer 40 on the sealing side, making it possible to achieve a desired surface roughness on the exposed surface of the heat seal layer 40 on the sealing side.

[0035] <Heat seal layer 40> The transfer film 2 includes a heat seal layer 40. The heat seal layer 40 functions as a heat sealable sealant layer when a barrier laminate such as barrier paper is used as a packaging material. The heat seal layer 40 also functions as a release layer from the support substrate 50 when a barrier laminate such as barrier paper is manufactured by the transfer method described later.

[0036] The heat-seal layer 40 is a layer that has heat-seal properties, specifically a layer that can be bonded to an object by heating and pressing, or a layer that can be bonded by fusing itself to another layer by heating and pressing. It should be noted that there is no prejudice to using the transfer film 2 for applications that do not require heat sealing.

[0037] In the transfer film 2, other layers may be provided between the heat seal layer and the support substrate, but it is preferable that the heat seal layer is in contact with the support substrate. With this configuration, the support substrate can be easily peeled off from the heat seal layer. For example, since the heat seal layer is less likely to remain on the support substrate after peeling, it is easy to recycle or reuse the support substrate.

[0038] The heat seal layer can be formed, for example, using a thermoplastic resin. Examples of thermoplastic resins include olefin polymers, ethylene vinyl acetate copolymers, and (meth)acrylic resins. Among these, olefin polymers are preferred.

[0039] In one embodiment, the heat seal layer contains an olefin polymer. This configuration provides, for example, a heat seal layer with excellent heat sealability and peelability, as well as a barrier laminate for packaging materials that has sufficient rigidity, strength, and heat resistance, and is highly recyclable.

[0040] Examples of olefin polymers include ethylene polymers and propylene polymers. Among these, ethylene polymers are preferred from the viewpoint of balancing heat sealability and peelability.

[0041] Examples of the ethylene-based polymer include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and ultra-low density polyethylene. From the viewpoint of heat sealability, low-density polyethylene, linear low-density polyethylene, and ultra-low density polyethylene are preferred. From the viewpoint of reducing environmental impact, polyethylene derived from biomass and / or recycled polyethylene may also be used.

[0042] The density of the high-density polyethylene is preferably more than 0.945 g / cm ３ . The upper limit of the density of the high-density polyethylene is, for example, 0.965 g / cm ３ . The density of the medium-density polyethylene is preferably more than 0.925 g / cm ３ and not more than 0.945 g / cm ３ . The density of the low-density polyethylene is preferably more than 0.900 g / cm ３ and not more than 0.925 g / cm ３ . The density of the linear low-density polyethylene is preferably more than 0.900 g / cm ３ and not more than 0.925 g / cm ３ . The density of the ultra-low density polyethylene is preferably not more than 0.900 g / cm ３ . The lower limit of the density of the ultra-low density polyethylene is, for example, 0.860 g / cm ３ . The density of the polyethylene is measured in accordance with JIS K7112 (1999).

[0043] Examples of the ethylene-based polymer also include ethylene-vinyl alcohol copolymers, ethylene-vinyl acetate copolymers, modified ethylene-vinyl acetate copolymers, ethylene-maleic anhydride copolymers, ethylene-(meth)acrylic acid copolymers, and ethylene-(meth)acrylate ester copolymers (e.g., ethylene-ethyl acrylate copolymers) such as ethylene-(meth)acrylate copolymers.

[0044] Examples of propylene polymers include propylene homopolymers, propylene random copolymers, and propylene block copolymers. A propylene homopolymer is a polymer composed solely of propylene. A propylene random copolymer is a random copolymer of propylene and ethylenically unsaturated monomers other than propylene (e.g., ethylene, 1-butene, 4-methyl-1-pentene, and other α-olefins). A propylene block copolymer is a copolymer having polymer blocks made of propylene and polymer blocks made of ethylenically unsaturated monomers other than propylene (e.g., ethylene, 1-butene, 4-methyl-1-pentene, and other α-olefins). From the viewpoint of reducing environmental impact, biomass-derived polypropylene and / or recycled polypropylene may be used. A propylene-maleic anhydride copolymer is also an example of a propylene polymer.

[0045] In one embodiment, the heat seal layer contains a (meth)acrylic resin. This configuration effectively suppresses blocking in the resulting heat seal layer.

[0046] As the acrylic resin, for example, one obtained by addition polymerization of one or more acrylic monomers selected from acrylic acid, methacrylic acid, acrylic acid esters, and methacrylic acid esters can be used. The acrylic monomer may be a comonomer having functional groups such as hydroxyl groups, epoxy groups, and amino groups in its molecular structure. The acrylic resin may also be an ionomer.

[0047] The barrier laminate of this disclosure is preferably manufactured by a transfer method, as described later. In the transfer method, a heat seal layer is formed on a support substrate, a barrier layer is formed on the heat seal layer, and then the heat seal layer and the barrier layer are transferred onto a substrate such as a paper substrate. Therefore, it is preferable to form the heat seal layer using a coating liquid that can form a coating film on a support substrate and that can form a coating film that has excellent peelability from the support substrate as well as heat sealability.

[0048] Furthermore, as will be described later, when manufactured by a transfer method, it is preferable to form the heat seal layer using a heat seal layer coating solution containing a thermoplastic ionomer. Ionomers are a general term for synthetic resins in which polymers are aggregated using the cohesive force of metal ions.

[0049] Examples of the above-mentioned metal ions include alkali metal ions and alkaline earth metal ions, specifically sodium, potassium, calcium, magnesium, and zinc.

[0050] Examples of ionomers of olefin polymers include metal salts of olefin-unsaturated carboxylic acid copolymers, metal salts of olefin-(meth)acrylic copolymers, metal salts of olefin-urethane copolymers, and metal salts of olefin-fluorine polymer copolymers.

[0051] Examples of the olefins mentioned above include α-olefins having 2 to 20 carbon atoms, such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 3-methyl-1-butene, 4-methyl-1-pentene, and 6-methyl-1-heptene. Among these, ethylene and propylene are preferred, with ethylene being more preferred.

[0052] Examples of the above-mentioned unsaturated carboxylic acids include unsaturated monocarboxylic acids such as (meth)acrylic acid, crotonic acid, and β-carboxyethyl (meth)acrylate; and unsaturated dicarboxylic acids such as maleic acid, itaconic acid, fumaric acid, and citraconic acid.

[0053] Among the above ionomers, ionomers of ethylene polymers are preferred, metal salts of ethylene-(meth)acrylic acid copolymers, metal salts of ethylene-(meth)acrylic copolymers, metal salts of ethylene-urethane copolymers, and metal salts of ethylene-fluorine polymer copolymers are more preferred, and metal salts of ethylene-(meth)acrylic acid copolymers are even more preferred.

[0054] The content of the olefin polymer in the heat seal layer is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. This further improves the heat sealability of the barrier laminate.

[0055] The heat seal layer may contain a rubber-based material along with the thermoplastic resin. Examples of rubber-based materials include thermoplastic rubber, natural rubber, butyl rubber, nitrile rubber, and chloroprene rubber. The rubber-based material can be used, for example, in mixture with the thermoplastic resin.

[0056] The heat seal layer is typically an unstretched layer. For example, a heat seal layer can be formed by applying and drying a heat seal layer coating solution containing an olefin polymer onto a support substrate, or by melt-extruding a resin composition containing an olefin polymer onto a support substrate. For the reasons mentioned above, the heat seal layer is preferably a cast coat layer formed using a coating solution containing an olefin polymer.

[0057] Examples of solvents for the heat seal layer coating liquid include water; alcohol solvents such as methanol, ethanol, 2-propanol, and 1-butanol; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; glycol solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether acetate, and propylene glycol monomethyl ether acetate; ester solvents such as methyl acetate, ethyl acetate, and butyl acetate; hydrocarbon solvents such as n-hexane, cyclohexane, benzene, toluene, and xylene; halogenated hydrocarbon solvents such as methylene chloride and chloroform; ether solvents such as dioxolane and tetrahydrofuran; nitrogen-containing solvents such as acetonitrile and N,N-dimethylformamide; and sulfur-containing solvents such as dimethyl sulfoxide.

[0058] For the preparation of the coating liquid for the heat seal layer, it is preferable to use an emulsion of an ionomer of an olefin polymer, more preferably a self-emulsifying emulsion, and even more preferably a self-emulsifying emulsion of a metal salt of an ethylene-(meth)acrylic acid copolymer. Such a coating liquid can, for example, form a coating film well on a support substrate, and moreover, can form a coating film that has excellent peelability from the support substrate, and the coating film also has excellent heat sealability.

[0059] It is preferable to use an aqueous ionomer emulsion as the emulsion described above. Such emulsions allow for relatively low control of the coating amount and, since they do not emit VOCs, they provide packaging materials with a low environmental impact.

[0060] The coating liquid for the heat seal layer may contain additives. Examples of additives include viscosity modifiers, defoamers, surfactants, leveling agents, lubricants, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, and dyes.

[0061] The thickness of the heat seal layer is preferably 0.5 μm or more, more preferably 0.8 μm or more, preferably 25 μm or less, and more preferably 15 μm or less. In one embodiment, the thickness of the heat seal layer is preferably 0.5 μm or more and 25 μm or less, and more preferably 0.8 μm or more and 15 μm or less. The thickness of the heat seal layer is preferably changed as appropriate depending on the strength of the heat seal layer, the processability of the transfer film 2, and the mass of the contents filled into the packaging material manufactured using the barrier laminate of this disclosure.

[0062] <Anchor Coat Layer 32> In one embodiment, the transfer film 2 may further include an anchor coat layer 32 between the heat seal layer 40 and the barrier layer 30. By providing the anchor coat layer 32, the adhesion between the heat seal layer 40 and the barrier layer 30 can be improved, and the occurrence of delamination between these layers can be suppressed. The anchor coat layer 32 may, for example, be in contact with the barrier layer 30 on one side and in contact with the heat seal layer 40 on the other side.

[0063] In one embodiment, the anchor coat layer 32 contains a resin component. Examples of the resin component include thermoplastic resins such as polyolefin resins (e.g., polyethylene resins and polypropylene resins), vinyl resins, styrene resins, (meth)acrylic resins, polyester resins, polyurethane resins, and polyamide resins; and cured products of thermosetting resins such as phenolic resins, melamine resins, epoxy resins, alkyd resins, thermosetting (meth)acrylic resins, unsaturated polyester resins, and thermosetting polyurethane resins. When using a thermosetting resin, it is preferable to use a curing agent such as an amine compound, a phenolic compound, an isocyanate compound, and a carboxylic acid compound in combination.

[0064] As for the resin component, polyester resins are preferred, for example, from the viewpoint of adhesion. Examples of polyester resins include polymers synthesized by polycondensation of acid components such as polycarboxylic acids, their esters and acid anhydrides with polyhydric alcohols, lactone ring-opening polymers, polyhydroxycarboxylic acid polymers, urea-modified polyesters, and urethane-modified polyesters. Urethane-modified polyester is a polyester having urethane bonds.

[0065] The thickness of the anchor coat layer is preferably 0.01 μm to 10 μm, more preferably 0.05 μm to 5 μm, and even more preferably 0.1 μm to 3 μm. If the thickness is above the lower limit, for example, sufficient adhesion strength can be obtained between the heat seal layer and the barrier layer. If the thickness is below the upper limit, for example, the anchor coat layer can be formed well on the heat seal layer.

[0066] <Barrier layer 30> The transfer film 2 includes a barrier layer 30. Preferably, the barrier layer 30 is a layer formed directly on one side of the heat seal layer 40, or on one side of the anchor coat layer 32 if an anchor coat layer 32 is provided.

[0067] The barrier layer 30 is a layer that suppresses the permeation of gases such as oxygen gas and water vapor. Therefore, for example, the barrier laminate 1 obtained by transferring the transfer layer from the transfer film 2 described later to the transfer target has excellent gas barrier properties. If the barrier layer 30 is an opaque layer, the barrier layer 30 may also have light-shielding properties against sunlight and fragrance-retaining properties for the contents.

[0068] The barrier layer 30 may be, for example, a metal vapor-deposited film formed by depositing a metal, or a vapor-deposited film formed by depositing an inorganic compound. In this specification, a layer formed by depositing such an inorganic material is referred to as an inorganic vapor-deposited layer.

[0069] Examples of metals that can be used to make up a metal vapor-deposited film include aluminum, chromium, tin, nickel, copper, silver, gold, and platinum. Among these, aluminum is preferred. In other words, an aluminum vapor-deposited film is preferred.

[0070] Examples of inorganic compounds constituting the above-mentioned deposited film include metal oxides, metal nitrides and metal carbides, indium tin oxide (ITO) and SiO Ｘ C Ｙ Examples of complex inorganic compounds include those listed above. Among these, metal oxides are preferred.

[0071] Examples of metallic elements that make up inorganic compounds include aluminum (Al), silicon (Si), magnesium (Mg), calcium (Ca), potassium (K), tin (Sn), sodium (Na), boron (B), titanium (Ti), lead (Pb), zirconium (Zr), yttrium (Y), zinc (Zn), vanadium (V), barium (Ba), and chromium (Cr).

[0072] The average composition of inorganic compounds is, for example, AlO ｘ SiO ｘ SiO ｘ C ｙ For example, MO ｘ or MO ｘ C ｙ It is expressed as follows: In the formula, M represents the metal element mentioned above, and the values ​​of x and y differ in range depending on the metal element.

[0073] Among metal oxides, aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, boron oxide, titanium oxide, zirconium oxide, and barium oxide are preferred, with aluminum oxide and silicon oxide being more preferred.

[0074] The inorganic vapor deposition layer may be formed from one metal or inorganic compound, or from a combination of two or more metals or inorganic compounds. The inorganic vapor deposition layer may consist of a single layer, or it may consist of two or more layers of the same or different compositions. Furthermore, the inorganic vapor deposition layer may be combined with the organic coating layer described later.

[0075] When the inorganic vapor deposition layer is multilayered, each layer can be deposited to have high gas barrier properties, thus achieving even higher gas barrier properties than a single layer. Furthermore, if the composition of each layer is different in a multilayered inorganic vapor deposition layer, the inorganic vapor deposition layer becomes a discontinuous layer, allowing for more efficient suppression of the permeation of oxygen gas and water vapor.

[0076] When an inorganic vapor-deposited layer is laminated as the barrier layer 30, the thickness of the inorganic vapor-deposited layer is preferably 3 nm to 300 nm, more preferably 4 nm to 250 nm, and even more preferably 5 nm to 200 nm. If the thickness is above the lower limit, for example, sufficient oxygen barrier properties and water vapor barrier properties can be obtained. If the thickness is below the upper limit, for example, the occurrence of cracks in the inorganic vapor-deposited layer can be suppressed.

[0077] Furthermore, the barrier layer 30 may be an organic coating layer formed by applying a coating agent containing a water-soluble polymer such as polyvinyl alcohol. The organic coating layer is formed, for example, by applying a coating solution containing a water-soluble polymer and at least one of one of a metal alkoxide and its hydrolysate, or tin chloride, either an aqueous solution or a water / alcohol mixed solution. These may be formed on the inorganic vapor-deposited layer described above.

[0078] <Protective Layer> The transfer film 2 may further have a protective layer on the surface of the barrier layer 30 opposite to the surface facing the heat seal layer 40. This can, for example, prevent damage to the barrier layer 30.

[0079] In one embodiment, the protective layer contains a resin component. Examples of resin components include polyethylene resins, polypropylene resins, polystyrene resins, vinyl chloride resins, polyester resins, (meth)acrylic resins, urethane resins, melamine resins, and epoxy resins. For example, urethane resin is preferred as the resin component.

[0080] The resin component content in the protective layer may be 50% by mass or more, 75% by mass or more, 90% by mass or less, or 95% by mass or less.

[0081] The protective layer may contain additives. Examples of additives include curing agents, antistatic agents, ultraviolet absorbers, colorants, heat stabilizers, and silane coupling agents. Examples of silane coupling agents include vinyl-based, epoxy-based, styryl-based, methacrylic-based, acrylic-based, amino-based, isocyanurate-based, ureido-based, mercapto-based, sulfide-based, or isocyanate-based silane coupling agents.

[0082] The thickness of the protective layer is preferably 0.01 μm to 5 μm, more preferably 0.05 μm to 3 μm, and even more preferably 0.1 μm to 1 μm.

[0083] For example, if the barrier layer 30 is an inorganic vapor-deposited layer composed of metal oxides such as aluminum oxide and silicon oxide, the transfer film 2 may have a barrier coat layer as a protective layer on the barrier layer 30. This can, for example, further improve the gas barrier properties of the barrier laminate.

[0084] In one embodiment, the barrier coating layer contains a gas barrier resin. Examples of gas barrier resins include ethylene-vinyl alcohol copolymer, polyvinyl alcohol, poly(meth)acrylonitrile; polyamides such as nylon 6, nylon 6,6 and polymethaxylylene adipamide (MXD6); polyester; polyurethane; and (meth)acrylic resin.

[0085] In another embodiment, the barrier coat layer is a gas barrier coating film formed by polycondensation treatment of a composition containing a metal alkoxide and a water-soluble polymer using a sol-gel method in the presence of a sol-gel catalyst, water, and an organic solvent. By providing such a barrier coat layer on an inorganic vapor-deposited layer, the gas barrier properties can be improved.

[0086] As the composition for forming such a barrier coating layer, the same type of coating liquid used for forming the organic coating layer described above can be used.

[0087] The thickness of the barrier coating layer is preferably 0.01 μm to 100 μm, more preferably 0.1 μm to 50 μm. This further improves the gas barrier properties of the barrier laminate. If the thickness is above the lower limit, for example, the gas barrier properties of the barrier laminate can be further improved, and the occurrence of cracks in the barrier layer 30 can be suppressed. If the thickness is below the upper limit, for example, a barrier laminate suitable for use in the manufacture of monomaterial packaging containers can be obtained.

[0088] <Adhesive Layer> The transfer film 2 of this disclosure may have an adhesive layer 20 on the surface of the barrier layer 30 opposite to the surface facing the heat seal layer 40. In the transfer method described later, the adhesive layer 20 is a layer for bonding the transfer object (for example, a paper member having a paper substrate) with the transfer film 2 having a support substrate 50, a heat seal layer 40, and a barrier layer 30. The transfer film 2 does not have to have an adhesive layer 20; for example, the adhesive layer 20 may be provided on the transfer object having a paper substrate 10.

[0089] In one embodiment, the adhesive layer 20 is a layer that is in contact with the barrier layer 30. In this embodiment, the adhesive layer 20 protects the barrier layer 30. For example, when stress such as bending load is applied to the transfer film 2, the adhesive layer 20 suppresses the occurrence of cracks in the barrier layer 30, and even if minute cracks begin to appear in the barrier layer 30 after stress is applied, it suppresses a decrease in gas barrier properties. Details of the adhesive layer 20 will be described later and will not be explained in this section.

[0090] <Layer Structure of Transfer Film> The following are some examples of the layer structure of the transfer film 2 used in the manufacture of the barrier laminate of this disclosure. • Barrier layer / HS layer / Support substrate • Barrier layer / AC layer / HS layer / Support substrate • Protective layer / Barrier layer / HS layer / Support substrate • Protective layer / Barrier layer / AC layer / HS layer / Support substrate • Protective layer / Protective layer / Barrier layer / HS layer / Support substrate • Protective layer / Protective layer / Barrier layer / AC layer / HS layer / Support substrate

[0091] "HS layer" refers to the heat seal layer, "AC layer" refers to the anchor coat layer, and " / " indicates the space between layers. Note that other layers may be included between these layers.

[0092] [Method for Manufacturing Transfer Film 2] A method for manufacturing the transfer film 2 used in the manufacture of the barrier laminate of the present disclosure may include a step of forming a heat seal layer on a support substrate (hereinafter also referred to as the "heat seal layer formation step"), a step of forming an anchor coat layer on the heat seal layer as needed (hereinafter also referred to as the "anchor coat layer formation step"), and a step of forming a barrier layer on the heat seal layer or the anchor coat layer (hereinafter also referred to as the "deposition film formation step"). The above manufacturing method may also include a step of forming a protective layer on the barrier layer (hereinafter also referred to as the "protective layer formation step").

[0093] <Heat seal layer formation process> The heat seal layer 40 can be formed, for example, by applying a heat seal layer coating liquid to one surface of the support substrate and drying it. It is preferable to provide the heat seal layer on a surface of the support substrate that has not been treated for easy adhesion, or on a surface where an easy adhesion layer has not been formed.

[0094] The coating liquid for the heat seal layer is preferably a coating liquid that can form a coating film on the support substrate 50 and that can form a coating film that has excellent peelability from the support substrate as well as heat sealability. Details of the coating liquid for the heat seal layer are as described above.

[0095] In one embodiment, a coating liquid for the heat seal layer is applied to a support substrate 50 and dried. Examples of known coating methods for the heat seal layer coating liquid include gravure coating, reverse coating, air knife coating, comma coating, die coating, blade coating, roll coating, bar coating, curtain coating, spray coating, lip coating, and dipping.

[0096] Methods for drying the applied heat-seal coating liquid include, for example, hot air drying, hot roll drying, and methods involving the application of heat such as infrared irradiation. The drying temperature is preferably 50°C to 200°C.

[0097] <Anchor Coat Layer 32 Formation Process> By providing an anchor coat layer on the heat seal layer 40, the adhesion of the barrier layer 30 can be improved and the vapor deposition surface can be smoothed. Depending on the required degree of gas barrier properties and the required interlayer strength, the anchor coat layer 32 may be omitted.

[0098] The anchor coating agent can be prepared, for example, by mixing the resin component or its precursor resin (e.g., thermosetting resin) described above with a curing agent as needed, an additive as needed, and a solvent. The details of these components are as described above, and the solvent can be the same as the solvent used for the heat seal layer coating liquid.

[0099] The anchor coat layer 32 can be formed, for example, by applying an anchor coat agent onto the heat seal layer and drying it. The known application methods described above are examples of how to apply the anchor coat agent. Methods for drying the applied anchor coat agent include, for example, applying heat such as hot air drying, hot roll drying, and infrared irradiation. The drying temperature is preferably 50°C to 150°C.

[0100] <Barrier Layer Formation Process> The barrier layer 30 can be formed by depositing an inorganic substance onto one side of the heat seal layer 40 or the anchor coat layer 32, or by applying a coating agent and drying it. Preferably, the barrier layer 30 is a layer formed directly on one side of the heat seal layer 40 or the anchor coat layer 32. Details of the barrier layer 30 are as described above and will not be explained further in this section.

[0101] When an inorganic vapor deposition layer is stacked as a barrier layer 30 by depositing an inorganic material, examples of methods for forming the inorganic vapor deposition layer include physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, ion plating, and cluster ion beam deposition, and chemical vapor deposition (CVD) methods such as plasma chemical vapor deposition, thermochemical vapor deposition, and photochemical vapor deposition. The inorganic vapor deposition film may also be a composite film comprising two or more different layers formed by using both physical vapor deposition and chemical vapor deposition methods in combination. Examples of heating means include resistance heating, induction heating, and electron beam heating.

[0102] The gas pressure in the deposition chamber is 10 －８ mbar or higher 10 －２ A pressure of 10 mbar or less is preferred. When forming a barrier layer 30 composed of an inorganic compound, for example, oxygen gas, nitrogen gas, or carbon dioxide gas is introduced as the reaction gas. When forming a barrier layer 30 composed of a metal oxide, the gas pressure after the introduction of oxygen gas is 10 mbar or less. －６ mbar or higher 10 －１ A value of mbar or less is preferable.

[0103] The amount of reaction gas introduced varies depending on the size of the deposition machine, etc. Inert gases such as argon, helium, and nitrogen may be used as carrier gases for the reaction gases, such as oxygen, to the extent that they do not cause problems.

[0104] When a roll-shaped transfer substrate is used and an inorganic vapor deposition layer is formed continuously, the transport speed of the transfer substrate on which the heat seal layer 40 and, if necessary, the anchor coat layer 32 are formed is, for example, 10 m / min or more and 800 m / min or less.

[0105] During the formation of the inorganic vapor deposition layer, Ar gas and O ２ or N ２ By pretreatment using such methods, the surface of the layer on which the inorganic vapor deposition layer is formed can be cleaned, and polar groups or free radicals can be generated on the surface of the layer, thereby increasing the adhesion between the inorganic vapor deposition layer and the layer.

[0106] In one embodiment, the PVD method uses, for example, a winding type deposition machine, where a substrate unwound from an unwinding roll is placed in a deposition chamber, where a deposition source heated in a crucible is evaporated, and an inorganic deposition layer is formed on the substrate on a cooled coating drum while oxygen gas or the like is blown out from an oxygen gas outlet as needed, and then the substrate is wound onto a winding roll.

[0107] In one embodiment, the PE-CVD method involves, for example, introducing a mixed gas containing, for instance, an organosilicon compound as a monomer gas, oxygen gas, and an inert gas into a deposition chamber, and generating a plasma to form an inorganic deposition layer composed of silicon oxide or the like on a substrate.

[0108] When laminating an organic coating layer formed by applying a coating agent containing a water-soluble polymer as a barrier layer 30, the coating agent (composition) for forming the organic coating layer can be prepared, for example, by mixing a water-soluble polymer with an aqueous solution or water / alcohol mixed solution containing at least one of one of a metal alkoxide and its hydrolysate, or tin chloride.

[0109] First, a metal alkoxide, a water-soluble polymer, a sol-gel catalyst, water, an organic solvent, and optionally a silane coupling agent are mixed to prepare a composition. A polycondensation reaction gradually proceeds within this composition.

[0110] Next, the composition is applied to the anchor coat layer 32 using the known application method described above and dried. This drying further promotes the polycondensation reaction between the metal alkoxide and the water-soluble polymer (and the silane coupling agent if the composition contains one), forming a composite polymer layer.

[0111] Next, the composition is heated, preferably at a temperature of 20°C to 250°C, more preferably at 50°C to 220°C, for a period of 1 second to 10 minutes. This allows an organic coating layer to be formed.

[0112] The above-mentioned substrate comprises a transfer substrate, a heat seal layer 40, and optionally an anchor coat layer 32. In this way, a transfer film 2 is obtained having the transfer substrate, the heat seal layer 40, optionally an anchor coat layer 32, and a barrier layer 30 in this order in the thickness direction.

[0113] <Protective Layer Formation Process> The protective layer can be formed, for example, by applying a protective layer coating liquid onto the barrier layer 30 and drying it. The known application method for the protective layer coating liquid is the one described above. The drying method for the applied protective layer coating liquid is, for example, a method of applying heat such as hot air drying, hot roll drying, and infrared irradiation. The drying temperature is preferably 50°C to 150°C.

[0114] The protective layer coating liquid can be prepared, for example, by mixing the resin components described above with a curing agent as needed, an additive as needed, and a solvent. The details of these components are as described above, and the solvent can be the same as the solvent used for the heat seal layer coating liquid.

[0115] A barrier coating layer, serving as a protective layer, can be formed, for example, by dissolving or dispersing a material such as a gas barrier resin in water or a suitable organic solvent, and then applying and drying the resulting coating solution onto the barrier layer. Alternatively, the barrier coating layer can also be formed, for example, by applying and drying a commercially available barrier coating agent.

[0116] In one embodiment, the barrier coating layer is the gas barrier coating film described above. The gas barrier coating film can be formed, for example, in the same manner as the organic coating layer described above.

[0117] [Barrier Laminate 1] In one embodiment, the barrier laminate of the present disclosure comprises a paper substrate, an adhesive layer, a barrier layer, and a heat seal layer in this order in the thickness direction.

[0118] In one embodiment, the barrier laminate of the present disclosure further comprises an anchor coat layer between the barrier layer and the heat seal layer. Here, the barrier layer and the heat seal layer or anchor coat layer (if an anchor coat layer is provided) are in contact. In one embodiment, the barrier laminate of the present disclosure may also have a printed layer on the side of the paper substrate opposite to the adhesive layer. Furthermore, in one embodiment, the barrier laminate of the present invention may also have a surface heat seal layer (second heat seal layer) on the side of the paper substrate layer opposite to the adhesive layer, or on the side of the printed layer opposite to the substrate layer.

[0119] In one embodiment, the barrier laminate of the present disclosure comprises a paper substrate, an adhesive layer, a barrier layer, and a heat seal layer in this order in the thickness direction. In one embodiment, the barrier laminate of the present disclosure further comprises an anchor coat layer between the barrier layer and the heat seal layer. The barrier laminate of this embodiment does not have a release layer between the barrier layer and the heat seal layer.

[0120] Figure 3 shows one embodiment of the barrier laminate of the present disclosure. The barrier laminate 1 in Figure 3 comprises a paper substrate 10, an adhesive layer 20, a barrier layer 30, and a heat seal layer 40 in this order in the thickness direction.

[0121] Figure 4 shows another embodiment of the barrier laminate of the present disclosure. The barrier laminate 1 in Figure 4 comprises a printed layer 12, a paper substrate 10, an adhesive layer 20, a barrier layer 30, an anchor coat layer 32, and a heat seal layer 40 in this order in the thickness direction.

[0122] The barrier laminate of this disclosure does not have a release layer between the heat seal layer and the barrier layer, resulting in high adhesion strength between these layers. Therefore, the barrier laminate of this disclosure suppresses the occurrence of delamination during the manufacturing process and during use.

[0123] A release layer is typically a layer provided as the surface layer on the transfer support side of a transfer film, in a conventional transfer film comprising a transfer support and a transfer layer, in order to improve the peelability of the transfer layer from the transfer support. In other words, the transfer layer includes a release layer as the surface layer on the transfer support side.

[0124] A release layer is typically a layer containing a release agent. Examples of release agents include waxes such as silicone wax, silicone oil, silicone resin, fluororesin, and phosphate ester. In one embodiment, the release layer contains a resin component. Examples of resin components include polyolefin, vinyl resin, styrene resin, (meth)acrylic resin, polyester, polyurethane, polycarbonate, polyamide, polyimide, and cellulose resin.

[0125] <Paper Substrate> The barrier laminate of this disclosure comprises a paper substrate. A barrier laminate comprising a paper substrate as a substrate is also called "barrier paper".

[0126] Compared to gas barrier plastic films, the barrier paper of this disclosure, having a paper base material, has a high paper content and a low plastic content, which contributes to reducing plastic waste, facilitates recycling and biodegradation, does not damage incinerators, and reduces incineration residue.

[0127] Examples of paper substrates include kraft paper, pure white roll paper, fine paper, medium-quality paper, glassine paper, Kent paper, processed paper, cardboard, and synthetic paper. Alternatively, paper substrates may be used in which a sealing layer or resin layer is formed on one or both sides of the paper material, such as clay-coated paper, lightly coated printing paper, coated printing paper (e.g., coated paper, cast-coated paper, and art paper), resin-coated paper, release paper, and double-sided coated release paper.

[0128] The paper substrate may contain additives. Examples of additives include sizing agents, lubricants, antioxidants, UV absorbers, light stabilizers, antistatic agents, fluorescent whitening agents, fluorescent decolorizing agents, fillers, reinforcing agents, pigments, and dyes. Additives can be added in any amount as needed, as long as they do not adversely affect other properties.

[0129] The adhesive layer side of the substrate may be pre-treated with physical surface treatments such as corona discharge treatment, ozone treatment, plasma treatment, glow discharge treatment, and sandblasting, as well as chemical surface treatments such as oxidation treatment using chemicals.

[0130] In one embodiment, the paper substrate comprises the paper material described above and a sealing layer or resin layer formed on the surface of the paper material facing the adhesive layer. The sealing layer has the function of suppressing the penetration of the adhesive constituting the adhesive layer into the paper material and stabilizing the adhesive strength of the adhesive layer.

[0131] In one embodiment, the sealing layer or resin layer contains a resin component. Examples of resin components include polyolefins such as polyethylene and polypropylene, vinyl resins such as vinyl chloride resins and vinyl acetate resins, styrene resins such as styrene-butadiene copolymers, thermoplastic resins such as (meth)acrylic resins, polyesters, polyamides, polyurethanes, and cellulose resins; and cured products of thermosetting resins.

[0132] In one embodiment, the sealing layer or resin layer contains additives. Examples of additives include lubricants, antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, fluorescent whitening agents, fluorescent decolorizing agents, fillers, reinforcing agents, pigments, and dyes. The sealing layer or resin layer preferably contains fillers. Examples of fillers include clay, silica, calcium carbonate, titanium dioxide, and zinc oxide.

[0133] The sealing layer or resin layer can be formed, for example, by a coating method or an extrusion coating method. The thickness of the sealing layer or resin layer is, for example, 0.1 μm or more and 30 μm or less.

[0134] Generally, since the surface of paper materials is porous and uneven, it is sometimes preferable to form a sealing layer of 20 μm or more on the surface of the paper material when directly forming a barrier layer on the paper material. However, in this disclosure, since barrier paper can be manufactured by the transfer method described later, it is not necessary to directly form a barrier layer on the paper material. Therefore, it is not necessary to form such a thick sealing coat layer on the surface of the paper material.

[0135] Furthermore, when forming a barrier layer in a vacuum deposition apparatus by placing paper material inside, paper dust generated from the paper material can hinder the reduction of pressure inside the deposition apparatus to a suitable atmospheric pressure. In such cases, it becomes difficult to form a stable barrier layer, which can easily lead to insufficient adhesion between the formed barrier layer and the paper material, resulting in unstable gas barrier properties. However, in this disclosure, since barrier paper can be manufactured by the transfer method described later, it is not necessary to place the paper material inside the deposition apparatus and directly form a barrier layer on the paper material. Therefore, the above-mentioned problems can be avoided.

[0136] Thus, in this disclosure, a paper substrate can be made of paper material and not impregnated with resin components, clay materials, etc. Furthermore, in this disclosure, a paper substrate can be made of paper material and not have a sealing layer, a resin layer, or a clay coat layer.

[0137] The paper substrate may consist of a single layer, or it may consist of two or more layers made of the same or different paper substrates. The paper substrates can be laminated together using any lamination method via conventionally known adhesive layers.

[0138] The thickness of the paper substrate is preferably 10 μm or more and 1500 μm or less, more preferably 15 μm or more and 1000 μm or less, and even more preferably 20 μm or more and 500 μm or less.

[0139] The basis weight of the paper substrate is preferably 10 g / m². ２ More than 1500g / m ２ More preferably, 15 g / m ２ More than 1000g / m ２ More preferably 20 g / m ２More than 500g / m ２ The following applies:

[0140] When a paper substrate is composed of multiple layers, the thickness of the paper substrate refers to the total thickness of the multiple layers. The same applies to basis weight.

[0141] If the paper substrate has such thickness and / or basis weight, it can impart appropriate strength and rigidity to, for example, a barrier laminate. Furthermore, if the thickness and / or basis weight is above the lower limit, it can suppress the occurrence of curling and warping during the manufacturing of the barrier laminate. If the thickness and / or basis weight is below the upper limit, the strength and rigidity will be within an appropriate range, and a decrease in work efficiency can be suppressed.

[0142] <Printed Layer 12> In one embodiment, the barrier laminate of the present disclosure comprises a printed layer 12 on a paper substrate. The barrier laminate of the present disclosure may have the printed layer on the surface of the paper substrate opposite to the adhesive layer side and / or on the surface of the paper substrate on the adhesive layer side, and it is preferable that the printed layer be on the surface of the paper substrate opposite to the adhesive layer side.

[0143] The printed layer 12 includes, for example, an image. Examples of images include letters, figures, symbols, pictures, patterns, and combinations thereof. The printed layer 12 is provided, for example, for indicating the contents of the packaging material, indicating the expiration date, indicating the manufacturer and seller, for decoration, and for adding an aesthetic appeal.

[0144] In one embodiment, the printed layer 12 is formed using a printing layer composition such as a thermoplastic resin composition, a thermosetting resin composition, and an energy-ray curable resin composition, each containing a colorant. Specifically, the printed layer 12 contains a thermoplastic resin, a cured product of a thermosetting resin, or a cured product of an energy-ray curable resin, and a colorant.

[0145] The thermoplastic resin composition contains a thermoplastic resin and a colorant. Examples of thermoplastic resins include polyolefins, vinyl resins, styrene resins, (meth)acrylic resins, polyesters, polyurethanes, polycarbonates, polyamides, polyimides, cellulose resins, petroleum resins, and fluororesins.

[0146] Thermoplastic resin compositions may contain additives. Examples of additives include lubricants, antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, fluorescent whitening agents, fluorescent decolorizing agents, fillers, reinforcing agents, pigments, and dyes.

[0147] A thermosetting resin composition is a composition that contains a thermosetting resin, a colorant, and optionally a curing agent, and hardens upon heating. In one embodiment, the thermosetting resin composition is a so-called thermosetting ink.

[0148] Examples of thermosetting resins include phenolic resins, melamine resins, urea resins, epoxy resins, unsaturated polyesters, thermosetting polyurethanes, silicone resins, and (meth)acrylic thermosetting resins. Examples of curing agents include epoxy curing agents and isocyanate curing agents. The thermosetting resin composition may contain the above-mentioned additives.

[0149] An energy-ray curable resin composition is a composition that contains a compound having an energy-ray curable functional group (hereinafter also referred to as "energy-ray curable compound") and a colorant, and is cured by energy-ray irradiation. In one embodiment, the energy-ray curable resin composition is a so-called ultraviolet-curable ink, and preferably a (meth)acrylic ultraviolet-curable ink.

[0150] Examples of energy rays include electromagnetic waves such as ultraviolet rays, infrared rays, X-rays, and gamma rays; and charged particle beams such as electron beams, proton beams, and neutron beams. Among these, ultraviolet rays are preferred from the viewpoint of curing speed, ease of obtaining irradiation sources, and cost.

[0151] Examples of energy-ray curable functional groups include ethylenically unsaturated groups such as (meth)acryloyl groups, vinyl groups, and allyl groups; as well as epoxy groups and oxetanyl groups. Examples of energy-ray curable compounds include compounds having ethylenically unsaturated groups, with compounds having two or more ethylenically unsaturated groups being preferred, and polyfunctional (meth)acrylate compounds being more preferred. Both monomers and oligomers can be used as polyfunctional (meth)acrylate compounds.

[0152] When the energy-ray curable compound is an ultraviolet-curable compound, the energy-ray curable composition (ultraviolet-curable resin composition) preferably contains at least one selected from a photopolymerization initiator and a photopolymerization accelerator. The energy-ray curable resin composition may contain the above-mentioned additives.

[0153] Examples of colorants include pigments and dyes. Specific examples of pigments include titanium dioxide, zinc oxide, carbon black, iron oxide, iron yellow, ultramarine, metallic pigments, pearl pigments, and fluorescent pigments. The printed layer may also be a high-luminosity layer with a high metallic sheen.

[0154] Compositions for printing layers may contain organic solvents and / or water from the viewpoint of improving coatability and other properties. Examples of organic solvents include hydrocarbon solvents such as toluene and xylene; ketone solvents such as acetone and methyl ethyl ketone; ester solvents such as ethyl acetate, cellosolve acetate and butyl cellosolve acetate; and alcohol solvents such as propanol.

[0155] For example, a printing layer can be formed by applying and drying a printing layer composition onto a paper substrate, then heating it to the temperature required for curing in the case of a thermosetting resin composition, or by irradiating it with energy rays in the case of an energy-ray curable resin composition. If the printing layer composition does not contain organic solvents and / or water, drying is not necessary.

[0156] Methods for forming the printed layer 12 include, for example, letterpress printing, flexographic printing, gravure printing, offset printing, screen printing, inkjet printing, and thermal transfer printing. The printed layer may be applied to the entire surface of the substrate or to only a part of it.

[0157] In one embodiment, the printed layer 12 contains a sublimation dye. The printed layer in this embodiment can be formed, for example, by sublimation transfer printing using a thermal transfer sheet.

[0158] The thickness of the printed layer is preferably 0.01 μm to 30 μm, more preferably 0.5 μm to 10 μm, and even more preferably 1 μm to 5 μm.

[0159] <Adhesive Layer> The barrier laminate 1 of this disclosure includes an adhesive layer 20 between the paper substrate 10 and the barrier layer 30. In the transfer method described later, the adhesive layer 20 is a layer for bonding the paper substrate 10, which is the object to be transferred, with the transfer film 2 which comprises a support substrate 50, a heat seal layer 40, and a barrier layer 30.

[0160] In one embodiment, the adhesive layer 20 is a layer that is in contact with the barrier layer 30. In this embodiment, the adhesive layer 20 protects the barrier layer 30.

[0161] The adhesive layer constituting the barrier laminate of this disclosure is a cured product of a hydrolyzable adhesive containing at least a water-suspendable polymer, and is characterized by having a Martens hardness HM of 5 MPa or less and a recovery rate of 20% or more.

[0162] The adhesive layer being a cured product of a water-soluble adhesive allows for the creation of a barrier laminate with excellent recyclability. A water-soluble adhesive is an adhesive containing at least a water-suspended polymer, and may also contain an aqueous medium containing water and a water-soluble organic solvent.

[0163] Here, "water-suspendable polymer" refers to a polymer that is not water-soluble (specifically, has a solubility of 10 g / L or less in water at 25°C) but is finely dispersed in water, such as in an emulsion or suspension.

[0164] Furthermore, "aqueous medium" refers to a medium containing 50% by mass or more of water, preferably 65% ​​by mass or more, and more preferably 80% by mass or more (upper limit: 100% by mass or less).

[0165] The adhesive layer being a cured product of a water-soluble adhesive allows for a barrier laminate with excellent recyclability. Specifically, a barrier laminate comprising a paper substrate and an adhesive layer being a cured product of a water-soluble adhesive has a pulp recovery rate of 80% by mass or more, preferably 85% by mass or more, and more preferably 90% by mass or more, of the paper substrate according to the disintegration method of JIS P8220:2012. The barrier laminate of this disclosure has a pulp recovery rate of 80% by mass or more after redisintegration and exhibits excellent recyclability.

[0166] Furthermore, the adhesive layer constituting the barrier laminate of this disclosure has a Martens hardness HM of 5 MPa or less and a recovery rate of 20% or more. By controlling the Martens hardness and recovery rate of the adhesive layer interposed between the paper substrate and the barrier layer to a predetermined range, when stress such as bending load is applied to the barrier laminate 1, the occurrence of cracks in the barrier layer can be suppressed, and even if minute cracks begin to occur in the barrier layer after stress is applied, the deterioration of gas barrier properties can be effectively suppressed.

[0167] The Martens hardness HM of the adhesive layer is preferably 4.5 MPa or less, and more preferably 4.0 MPa or less. Having such a Martens hardness HM of the adhesive layer more effectively suppresses the delamination of the adhesive layer in the barrier laminate due to stress. The lower limit of the Martens hardness HM of the adhesive layer is not particularly limited, but is preferably 0.1 MPa or more, more preferably 0.3 MPa or more, and even more preferably 0.5 MPa or more.

[0168] Restoration rate of the adhesive layer η ＩＴ The percentage is preferably 23% or more, and more preferably 25% or more. ＩＴ This allows for more effective suppression of the delamination of the adhesive layer in the barrier laminate due to stress. Restoration rate of the adhesive layer η ＩＴ The upper limit is not particularly limited, but it is preferably 60% or less, and more preferably 55% or less.

[0169] Furthermore, the maximum load F of the adhesive layer ｍａｘ Maximum indentation depth (reachable depth) h ｍａｘ This is not particularly limited, but the maximum load F of the adhesive layer. ｍａｘ Maximum indentation depth (reachable depth) h ｍａｘ The lower limit is preferably 4.0 μm or more, more preferably 4.5 μm or more, and even more preferably 5.0 μm or more. Maximum load F of the adhesive layer ｍａｘ Maximum indentation depth (reachable depth) h ｍａｘThe upper limit is not particularly limited, but it is preferably 10 μm or less.

[0170] The Martens hardness of the adhesive layer is HM, and the recovery rate is η. ＩＴ , maximum load F ｍａｘ Maximum indentation depth (reachable depth) h ｍａｘ This can be measured using a surface film property tester (PICODENTOR HM-500, manufactured by Fischer Instruments Co., Ltd.).

[0171] Specifically, a diamond indenter (Vickers indenter) with a face angle of 136° is used to press the diamond indenter into the adhesive layer, and the maximum load F is applied. ｍａｘ and maximum load F ｍａｘ Maximum indentation depth (reachable depth) h ｍａｘ Therefore, the Martens hardness can be determined (Martens hardness HM = F ｍａｘ / (26.43 x h ｍａｘ ^2)). Also, the amount of work W required for elastic deformation recovery during compression. ｅｌａｓｔ Total mechanical pushing work volume W ｔｏｔａｌ Therefore, the recovery rate η ＩＴ (Recovery rate η) can be calculated. ＩＴ = W ｅｌａｓｔ / W ｔｏｔａｌ ).

[0172] Furthermore, while the softening point of the adhesive layer is not particularly limited, the upper limit of the softening point of the adhesive layer is preferably 250°C or lower, more preferably 200°C or lower, and even more preferably 190°C or lower. The lower limit of the softening point of the adhesive layer is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 70°C or higher.

[0173] The softening point of the adhesive layer can be measured by local thermal analysis using a thermal probe. Specifically, in local thermal analysis using a thermal probe, the thermal probe is in contact with the surface of the adhesive layer, and the displacement of the thermal probe in the direction normal to the surface of the adhesive layer from before heating is measured while the temperature is increased, thereby obtaining a thermal expansion curve. In local thermal analysis, the thermal probe is pushed up as the components contained in the adhesive layer expand due to heating. When the adhesive layer reaches a certain temperature due to heating, the slope (displacement / temperature) of the thermal expansion curve changes as the components of the adhesive layer undergo structural transitions. In particular, when the structural transition of the components of the adhesive layer changes from expansion to softening, the tip of the thermal probe enters the components, causing the thermal probe to descend. The point where the displacement of the thermal probe changes from rising to falling corresponds to the peak of the thermal expansion curve and is called the softening point. The softening point of the adhesive layer can be obtained by reading the temperature of the peak of the thermal expansion curve. Furthermore, measurements are performed at five or more locations on the same surface, and the arithmetic mean of the five values ​​measured with good reproducibility is recorded.

[0174] The nanoTA from Anasys Instruments can be used as the measuring device, and the PR-EX-AN2-300-5 from Anasys Instruments can be used as the thermal probe.

[0175] The Martens hardness HM of the adhesive layer, the recovery rate, and the maximum load F. ｍａｘ Maximum indentation depth (reachable depth) h ｍａｘThe hardness and softening point can be controlled, for example, by selecting the type of resin (water-suspended polymer) that constitutes the adhesive layer. While not particularly limited, examples of water-suspended polymers include vinyl acetate-acrylic copolymers, styrene-butadiene copolymers, acrylic resins such as methyl acrylate copolymers, methyl methacrylate copolymers, styrene-acrylic copolymers, and styrene-methacrylic copolymers, olefin-unsaturated carboxylic acid copolymers such as ethylene-acrylic acid copolymers and ethylene-methacrylic acid copolymers, and at least one EVA-based resin or modified acrylic copolymer selected from the group consisting of vinyl acetate polymers, ethylene-vinyl acetate copolymers, and acrylic-vinyl acetate-ethylene copolymers. These may be used individually or in combination of two or more. Among these, EVA-based resins are preferred from the viewpoint of achieving a desired Martens hardness HM and recovery rate of the adhesive layer, as well as recyclability. ABS (acrylonitrile-styrene-butadiene) may also be used as the water-suspended polymer.

[0176] The lower limit of the adhesive layer thickness is preferably 0.3 μm or more, more preferably 0.5 μm or more, and even more preferably 1.0 μm or more. A thickness of 0.5 μm or more in the adhesive layer improves the adhesion between the paper substrate and the barrier layer. The upper limit of the adhesive layer thickness is preferably 20 μm or less, more preferably 10 μm or less, and even more preferably 7 μm or less. A thickness of 20 μm or less in the adhesive layer allows for a barrier laminate with even greater recyclability.

[0177] The lower limit of the application amount in the solid content of the adhesive layer is preferably 0.3 g / m². ２ More preferably, 0.5 g / m ２ The above, and more preferably 0.7 g / m ２ That concludes the explanation. The amount of adhesive applied to the solid content of the adhesive layer is 0.5 g / m². ２ This improves the adhesion between the paper substrate and the barrier layer. The upper limit of the amount of solids in the adhesive layer applied is preferably 6 g / m². ２ The following is more preferable: 5 g / m ２The following, and more preferably 4 g / m ２ The following applies: The amount of adhesive applied to the solid content of the adhesive layer is 6 g / m². ２ The following conditions allow for the creation of a barrier laminate with even greater recyclability.

[0178] The adhesive layer and the hydrolyzable adhesive may contain additives. Examples of additives include dispersants, surfactants, antioxidants, UV absorbers, light stabilizers, antistatic agents, fluorescent whitening agents, fluorescent decolorizing agents, plasticizers, lubricants, mold release agents, fillers, reinforcing agents, antiblocking agents, flame retardants, crosslinking agents, pigments, and dyes.

[0179] Examples of commercially available hydrolyzable adhesives include RC-1500, GHA-302S, DBA-137, DBA-155L, AC-60, PZ-804, PZ-905, PZ-907 (all manufactured by Saiden Chemical), RAN-032-4A, AV-650Y-5LL, AV-880L (all manufactured by Nichiei Chemical), and LW9112 (manufactured by Henkel).

[0180] The adhesive layer can be formed by applying a water-soluble adhesive to, for example, a paper substrate and / or a barrier layer using methods such as the direct gravure roll coating method, gravure roll coating method, kiss coating method, reverse roll coating method, fontein method, and transfer roll coating method, and then drying after bonding them together.

[0181] <Barrier Layer> The barrier laminate of this disclosure comprises a barrier layer. The barrier layer is preferably a layer that is directly vapor-deposited on one side of the heat seal layer, or on one side of the anchor coat layer if an anchor coat layer is provided. Details of the barrier layer are as described above and will not be explained further in this section.

[0182] <Protective Layer> The barrier laminate of this disclosure may include a protective layer on the surface of the barrier layer opposite to the surface facing the heat seal layer. This can, for example, suppress damage to the barrier layer. Details of the protective layer are as described above and will not be explained further in this section.

[0183] <Anchor Coat Layer> The barrier laminate of this disclosure may further include an anchor coat layer between the heat seal layer and the barrier layer. By providing an anchor coat layer, the adhesion between the heat seal layer and the barrier layer can be improved, and the occurrence of delamination between these layers can be suppressed. The anchor coat layer may, for example, be in contact with the barrier layer on one side and in contact with the heat seal layer on the other side. Details of the anchor coat layer are as described above and will not be explained further in this section.

[0184] <Heat Seal Layer> The barrier laminate of this disclosure includes a heat seal layer as a surface layer on one side. In one embodiment, the heat seal layer functions as a heat seal layer. For example, when the barrier laminate is used as a packaging material, the heat seal layer functions as a heat sealable sealant layer. Furthermore, when the barrier laminate is manufactured by the transfer method described later, the heat seal layer also functions as a release layer from the support substrate. Details of the heat seal layer are as described above and will not be explained further in this section.

[0185] <Functional Layer> In addition to the layers described above, the barrier laminate of this disclosure may also include a functional layer. The functional layer is a layer that imparts to the barrier laminate functions such as light shielding, mechanical strength, deformation resistance, impact resistance, pinhole resistance, heat resistance, sealing, quality preservation, workability, and hygiene.

[0186] In one embodiment, the functional layer contains a resin component. Examples of resin components include polyolefins, vinyl resins, styrene resins, (meth)acrylic resins, polyesters, polyurethanes, polycarbonates, polyamides, polyimides, fluororesins, cellulose resins, and ionomer resins.

[0187] The functional layer may contain the above-mentioned additives according to its function. The thickness of the functional layer is, for example, 1 μm to 300 μm.

[0188] <Layer Structure and Applications of Barrier Paper> The following are some examples of the layer structure of the barrier paper disclosed in this disclosure: • Paper substrate / adhesive layer / barrier layer / HS layer • Paper substrate / adhesive layer / barrier layer / AC layer / HS layer • Paper substrate / adhesive layer / protective layer / barrier layer / HS layer • Paper substrate / adhesive layer / protective layer / barrier layer / AC layer / HS layer • Printed layer / Paper substrate / adhesive layer / barrier layer / HS layer • Printed layer / Paper substrate / adhesive layer / barrier layer / AC layer / HS layer • Printed layer / Paper substrate / adhesive layer / protective layer / barrier layer / HS layer • Printed layer / paper substrate / adhesive layer / barrier layer / AC layer / HS layer • Paper substrate / Printing layer / Adhesive layer / Protective layer / Barrier layer / HS layer • Paper substrate / Printing layer / Adhesive layer / Protective layer / Barrier layer / AC layer / HS layer • Paper substrate / Adhesive layer / Protective layer / Protective layer / Barrier layer / HS layer • Paper substrate / Adhesive layer / Protective layer / Protective layer / Barrier layer / AC layer / HS layer • Printing layer / Paper substrate / Adhesive layer / Protective layer / Protective layer / Barrier layer / AC layer / HS layer • Paper substrate / Printing layer / Adhesive layer / Protective layer / Protective layer / Barrier layer / AC layer / HS layer

[0189] "HS layer" refers to the heat seal layer, "AC layer" refers to the anchor coat layer, and " / " indicates the interlayer. The paper substrate may also be paper material / sealing layer (or resin layer). In this case, for example, the "paper substrate / adhesive layer" part in the above layer configuration becomes "paper material / sealing layer (or resin layer) / adhesive layer".

[0190] The barrier paper of this disclosure has a pulp recovery rate of 80% by mass or more, preferably 85% by mass or more, and more preferably 90% by mass or more, of the paper substrate in accordance with the disintegration method of JIS P8220:2012. The barrier paper of this disclosure has a pulp recovery rate of 80% by mass or more after redisintegration and possesses excellent recyclability.

[0191] The oxygen permeability of the barrier laminate such as barrier paper disclosed herein is 10 cc / m³. ２ Preferably, the pressure is 24hr / atm or less, and 5cc / m ２ More preferably 24hr / atm or less, and 3cc / m ２A pressure of 24hr / atm or less is more preferable, and 1.5cc / m³ is even more preferable. ２ A value of 24hr / atm or less is particularly preferred. The lower limit of oxygen permeability is, for example, 0.01 cc / m³. ２ / 24hr / atm is also acceptable.

[0192] Furthermore, the oxygen permeability of the barrier laminate, such as the barrier paper described herein, after being folded into quarters is 13 cc / m². ２ Preferably, the pressure is 24hr / atm or less, and 12cc / m³ ２ A pressure of 24hr / atm or less is more preferable, and 11.5 cc / m³ is preferable. ２ A value of 24hr / atm or less is even more preferable. The lower limit of oxygen permeability is, for example, 0.01 cc / m³. ２ Oxygen permeability may be measured at 24hr / atm. Oxygen permeability is measured in accordance with JIS K7126 under conditions of 23°C and 90% RH.

[0193] The water vapor permeability of the barrier laminate such as barrier paper disclosed herein is 20 g / m². ２ Preferably 24hr or less, and 10 g / m ２ More preferably 24hr or less, and 5g / m ２ A rate of 24hr or less is more preferable, and 1.5 g / m² is even more preferable. ２ A value of 24hr or less is particularly preferred. The lower limit of water vapor transmission is, for example, 0.01 g / m³. ２ / 24hr is also acceptable.

[0194] Furthermore, the water vapor transmission rate of the barrier laminate such as the barrier paper disclosed herein after being folded into quarters is 20 g / m². ２ Preferably 24hr or less, and 10 g / m ２ More preferably 24hr or less, and 5g / m ２ A rate of 24 hours or less is more preferable, and 3 g / m³ ２ A value of 24hr or less is particularly preferred. The lower limit of water vapor transmission is, for example, 0.01 g / m³. ２ / 24hr is also acceptable. Water vapor transmission rate is measured in accordance with JIS K7129 under conditions of 40°C and 90% RH.

[0195] The barrier laminate of this disclosure can be suitably used for packaging materials such as packaging bags. As described above, the barrier laminate of this disclosure has excellent interlayer adhesion and suppresses delamination, so the packaging material equipped with the barrier laminate suppresses the occurrence of so-called delamination during use.

[0196] Furthermore, when the total thickness of the barrier laminate of this disclosure is 150 μm or less, it can be suitably used for flexible paper packaging and flexible paper substrate devices. Flexible paper packaging and flexible paper substrate devices equipped with this barrier laminate possess high oxygen and water vapor barrier properties and high recyclability.

[0197] The packaging material of the present disclosure comprises the barrier laminate of the present disclosure. The packaging material of the present disclosure may further comprise, if necessary, layers having various functions together with the barrier laminate.

[0198] For example, a packaging material can be manufactured by folding the barrier laminate in half so that the base material, such as a paper substrate, is on the outside and the heat-seal layer is on the inside, overlapping the layers, and then heat-sealing the edges. Alternatively, a packaging material can be manufactured by overlapping multiple barrier laminates so that their heat-seal layers face each other, and then heat-sealing the edges. The entire packaging material may be composed of the barrier laminate, or only a portion of the packaging material may be composed of the barrier laminate.

[0199] Examples of heat sealing forms for packaging materials include side seals, two-side seals, three-side seals, four-side seals, envelope seals, gusset seals (pillow seals), pleated seals, flat-bottom seals, square-bottom seals, and gusset seals. Stand-up pouches are also possible. Examples of heat sealing methods include bar seals, rotary roll seals, belt seals, impulse seals, high-frequency seals, and ultrasonic seals.

[0200] Examples of contents to be filled into the packaging material include liquids, powders, and gels, and may be food or non-food items. After filling the packaging material with contents, the opening of the packaging material is heat-sealed to obtain the package.

[0201] The contents specifically include coffee beans, tea leaves; cheese, snacks, rice crackers, fresh and semi-fresh confectionery, nuts, vegetables, fruits, fish and meat products, processed fish products, dried fish, smoked foods, preserved foods, raw rice, cooked rice dishes, mochi, baby food, jam, mayonnaise, ketchup, cooking oil, dressings, sauces, spices, dairy products, and pet food; beverages such as beer, wine, fruit juice, green tea, and coffee; pharmaceuticals; cosmetics, shampoo, conditioner, and detergents; and metal and electronic components.

[0202] [Method for Manufacturing a Barrier Laminate] The barrier laminate of this disclosure can be obtained, for example, by the transfer method described below. The method for manufacturing a barrier laminate by the above transfer method comprises: a step of preparing a paper substrate to be transferred and a transfer film of this disclosure (hereinafter also referred to as the "preparation step"); a step of applying a hydrolyzable adhesive containing a water-suspendable polymer and an aqueous medium to the barrier layer of the transfer film (hereinafter also referred to as the "coating step"); a step of bonding the paper substrate to the surface of the transfer film coated with the hydrolyzable adhesive, and then curing the hydrolyzable adhesive to obtain an intermediate laminate (hereinafter also referred to as the "bonding step"); and a step of peeling the support substrate from the heat-seal layer of the intermediate laminate (hereinafter also referred to as the "peeling step").

[0203] Figures 5A, 5B, and 5C are process diagrams showing an example of a method for manufacturing the barrier laminate according to the present disclosure.

[0204] Through the aforementioned bonding and peeling processes, a transfer layer comprising a barrier layer and a heat-seal layer in that order in the thickness direction can be transferred onto the paper substrate, which is the transfer target. The barrier layer transferred onto the paper substrate by the transfer method is less contaminated, has better adhesion between the barrier layer and the adhesive layer, is more homogeneous and stable, and has superior gas barrier properties compared to a barrier layer directly vapor-deposited onto the paper substrate.

[0205] The manufacturing method disclosed herein allows for the provision of a barrier layer on a paper substrate, similar to the case where a resin substrate is used, thereby enabling the creation of barrier paper that has excellent gas barrier properties and is environmentally friendly.

[0206] Furthermore, in a method for forming a heat seal layer by forming a barrier layer on a paper substrate and then applying a heat seal coating liquid onto the barrier layer, the gas barrier properties of the barrier layer may decrease due to cracks or thermal damage to the barrier layer caused by tension or drying during the formation of the heat seal layer. The manufacturing method of this disclosure can avoid such a decrease. In addition, the heat seal layer can suppress deterioration of the barrier layer during the application process and during the peeling process when the support substrate is peeled off.

[0207] The manufacturing method disclosed herein can suppress the deterioration of the barrier layer, and therefore, for example, when a barrier laminate is used as a packaging material, the degree of deterioration due to bending, folding, and heat seal damage can be reduced.

[0208] It should be noted that a reference barrier paper (hereinafter also referred to as "reference barrier paper") with a different layer structure from the barrier paper disclosed herein may also be considered, having a layer structure of paper substrate / adhesive layer / barrier layer / release layer / primer layer / heat seal layer if necessary.

[0209] One example of a method for manufacturing the reference barrier paper is to bond a paper substrate and a transfer film comprising a transfer substrate, a release layer, and a barrier layer via an adhesive layer to form a laminate (1) having a layer structure of paper substrate / adhesive layer / barrier layer / release layer / transfer substrate; peel off the transfer substrate from the laminate (1) to form a laminate (2) having a layer structure of paper substrate / adhesive layer / barrier layer / release layer; and optionally form a primer layer and a heat seal layer on the release layer of the laminate (2) to obtain the reference barrier paper. Hereinafter, this manufacturing method will also be referred to as the "reference transfer method".

[0210] The reference transfer method has several advantages over barrier layers transferred onto paper substrates, including less contamination, higher adhesion between the barrier layer and adhesive layer, greater homogeneity and stability, and superior gas barrier properties, compared to barrier layers directly vapor-deposited onto paper substrates.

[0211] However, since the reference barrier paper has a release layer between the heat seal layer and the barrier layer, the adhesion strength between these layers may not be sufficient. In addition, in the reference transfer method, after peeling off the transfer substrate, it is necessary to separately form a heat seal layer (heat sealable sealant layer) on the release layer, for example, when manufacturing packaging materials, which increases the number of manufacturing steps.

[0212] In contrast, the barrier paper of this disclosure does not have a release layer between the heat seal layer and the barrier layer, resulting in sufficiently high adhesion strength between these layers. Furthermore, in the manufacturing method of this disclosure, the heat seal layer also serves as a release layer from the support substrate, eliminating the need to separately form a heat seal layer (heat sealable sealant layer) after peeling off the support substrate, thus reducing the number of manufacturing steps.

[0213] Furthermore, in one embodiment of the manufacturing method disclosed herein, the heat seal layer and the barrier layer are pre-formed on a support substrate for the thin film. In the manufacturing of the transfer film, processing is possible in a wider and longer form than with a paper substrate, thus reducing the cost per unit area of ​​the barrier paper.

[0214] Thus, while both the reference barrier paper and the reference transfer method have excellent advantages, the barrier paper and its manufacturing method described herein are even superior in the respects mentioned above and can be said to produce advantageous effects.

[0215] <Preparation Process> In the preparation process, the paper substrate to be transferred and the transfer film are prepared.

[0216] The paper substrate may be a single sheet or a continuous sheet wound into a roll.

[0217] The paper substrate may consist of only the paper substrate, or it may consist of the paper substrate and a printed layer provided on the paper substrate. Preferably, the printed layer is provided on the side of the paper substrate opposite to the side on which the adhesive layer is provided. In the preparation step, the paper substrate may be manufactured by forming the printed layer on the paper substrate, or a paper substrate with a printed layer already provided on it may be used. The printed layer may be formed between the bonding step and the peeling step, or after the peeling step, but from the viewpoint of suppressing a decrease in gas barrier properties, it is preferable to form the printed layer before the bonding step.

[0218] The paper substrate may consist only of paper material, or it may consist of paper material and a sealing layer or resin layer formed on the paper material. By using a paper substrate with a sealing layer or resin layer on the paper material, the penetration of the adhesive into the paper material can be suppressed, and the adhesive strength of the adhesive layer can be stabilized. In the preparation step, the paper substrate may be made by forming the sealing layer or resin layer on the paper substrate, or a paper substrate that already has a sealing layer or resin layer on the paper material, such as coated paper, may be used.

[0219] In addition to forming the printing layer described above, the paper substrate may be decorated on the side opposite to the side where the adhesive layer is applied, for example, by foil stamping, embossing, and shaping. The paper substrate obtained in this way may be used. Decoration may be performed between the bonding and peeling steps, or after the peeling step, but from the viewpoint of suppressing a decrease in gas barrier properties, it is preferable to perform the decoration before the bonding step. Details of each element are as described above and are omitted here.

[0220] In the preparation step, the transfer film of this disclosure, which has been prepared in advance, is prepared.

[0221] <Coating Process> In the coating process, the hydrolyzable adhesive may be applied to either the object to be transferred or the transfer film, or to both. Alternatively, the hydrolyzable adhesive may be supplied between the object to be transferred and the transfer film to simultaneously form an adhesive layer and bond the object to be transferred and the transfer film.

[0222] In the coating process, in one embodiment, a water-soluble adhesive is applied to the transfer object, and then the transfer film is bonded to it. In one embodiment, it is preferable to apply the water-soluble adhesive to a sealing layer or resin layer on a paper substrate.

[0223] <Bonding Process> In the bonding process, the paper substrate to be transferred and the transfer film are bonded together by wet lamination using a water-soluble adhesive applied to either side, with the support substrate of the transfer film facing outwards and the barrier layer facing inwards (towards the transfer object). The water-soluble adhesive is then cured to form an adhesive layer, and an intermediate laminate is obtained (see Figures 5A and 5B).

[0224] The bonding process can be carried out using generally known equipment, temperature, and pressure, depending on the type and characteristics of the hydrolyzable adhesive. For example, after applying the hydrolyzable adhesive to the transfer object and / or transfer film, the transfer object and transfer film are placed on top of each other, and then heated to cure the adhesive and obtain an intermediate laminate. Pressure may be applied as needed.

[0225] The method and pressure of pressing the intermediate laminate during the bonding process should preferably be selected and set in a way that minimizes damage to the barrier layer. The pressure during pressing should preferably be between 0.1 MPa and 10 MPa.

[0226] <Peeling Process> In the peeling process, the support substrate is peeled from the heat-sealed layer of the intermediate laminate (see Figure 5C). For example, after sufficient adhesive strength has been achieved by the adhesive layer between the object to be transferred and the transfer film, the support substrate is peeled from the intermediate laminate. Peeling can be performed using known equipment and temperatures.

[0227] In one embodiment, the support substrate of the transfer film may be peeled off while the transfer object and the transfer film are bonded together via an adhesive layer. In this way, a barrier laminate such as the barrier paper of the present disclosure can be obtained.

[0228] For example, if the intermediate laminate is a continuous sheet wound in a roll shape, a release roll may be used to continuously peel the support substrate from the heat seal layer of the intermediate laminate, and the barrier laminate and the support substrate may be wound up separately.

[0229] <<Packaging 100 using barrier laminate 1A>> Next, we will describe packaging 100 in which the contents P are packaged using the barrier laminate 1 described above (see Figures 3 and 4).

[0230] Figures 6A and 6B show one embodiment of a packaging body formed using a barrier laminate. Figure 6A is a perspective view of the packaging body formed using a barrier laminate, and Figure 6B is a cross-section of Figure 6A along the line b-b.

[0231] As shown in Figures 6A and 6B, the packaging body 100 comprises an upper surface 101, a lower surface 102, a right side surface 103, a left side surface 104, a front side surface 105, and a rear side surface 106, and is a rectangular parallelepiped-shaped packaging body in which a rectangular parallelepiped-shaped contents P is packaged by a rectangular barrier laminate 1.

[0232] The top surface 101, bottom surface 102, right side surface 103, and left side surface 104 of the packaging body 100 are formed by enclosing the side surfaces of the rectangular parallelepiped contents P with the heat-seal layer 40 of the rectangular barrier laminate 1 facing the inner surface.

[0233] Here, as shown in Figure 6B, the edges of the barrier laminate 1 that are substantially parallel to the side surface of the contents P are heat-sealed by bringing the heat-seal layers 40 of one edge and the other edge together, i.e., the inner surfaces of the barrier laminate 1 facing each other, and a seal portion 110 is formed on the upper surface 101. In addition, the edges of the barrier laminate 1 that are substantially perpendicular to the side surface of the contents P are folded and sealed as appropriate to form the front surface 105 and the rear surface 106. The seal portion 110 may be joined to the upper surface 101 as needed.

[0234] <<Packaging 200 using Barrier Laminate 1>> Next, we will describe packaging 200 in which contents P are packaged using a barrier laminate 1 having a surface heat-seal layer on a paper substrate.

[0235] Figures 7A and 7B show one embodiment of a packaging body formed using a barrier laminate. Figure 7A is a perspective view of the packaging body formed using a barrier laminate, and Figure 7B is a cross-section of Figure 7A along the line b-b.

[0236] As shown in Figures 7A and 7B, the packaging body 200 comprises an upper surface 201, a lower surface 202, a right side surface 203, a left side surface 204, a front side surface 205, and a rear side surface 206, and is a rectangular parallelepiped-shaped packaging body in which a rectangular parallelepiped-shaped contents P is sealed and packaged by a rectangular barrier laminate 1.

[0237] As shown in Figures 7A and 7B, the heat-seal layer 40 of the rectangular barrier laminate 1 is on the inner surface and the surface heat-seal layer is on the outer surface, and the side surfaces of the rectangular parallelepiped contents P are wrapped around it, thereby forming the top surface 101, bottom surface 102, right side surface 103, and left side surface 104 of the packaging body 100.

[0238] Here, the edges of the barrier laminate 1 that are substantially parallel to the side surface of the contents P are overlapped and heat-sealed, as shown in Figure 7B, so that the heat-seal layer 40 of one edge and the surface heat-seal layer of the other edge face each other, and a seal portion 210 is formed on the upper surface 201. In addition, the edges of the barrier laminate 1 that are substantially perpendicular to the side surface of the contents P are folded and sealed as appropriate to form the front side surface 205 and the rear side surface 206.

[0239] The barrier laminates of this disclosure will be described in more detail based on the following examples, but the barrier laminates of this disclosure are not limited to these examples.

[0240] The main products used in the examples are as follows: [Paper substrate] Paper substrate A: Daio Paper Corporation, Nagoya Sarashi Ryuo, basis weight 50 g / m² ２ , one-sided gloss finish. • Paper base material B: Manufactured by Daio Paper Corporation, Nagoya Sarashi Ryuo, basis weight 70 g / m² ２ , one-sided gloss finish. • Paper base material C: Manufactured by Daio Paper Corporation, Nagoya Sarashi Ryuo, basis weight 100 g / m² ２ , Single-glazed item.

[0241] [Adhesives] ・Adhesive A: Saiden Chemical Co., Ltd., DBA-137 (Water-soluble adhesive containing EVA resin as a water-suspended polymer) ・Adhesive B: Saiden Chemical Co., Ltd., DBA-155L (Water-soluble adhesive containing EVA resin and vinyl acetate / acrylic copolymer as a water-suspended polymer) ・Adhesive C: Saiden Chemical Co., Ltd., RC-1500 (Water-soluble adhesive containing acrylic / styrene copolymer as a water-suspended polymer) ・Adhesive D: Saiden Chemical Co., Ltd., PZ-905 (Water-soluble adhesive containing EVA resin and vinyl acetate / acrylic copolymer as a water-suspended polymer) ・Adhesive E: Saiden Chemical Co., Ltd., PZ-907 (Water-soluble adhesive containing styrene-butadiene rubber and EVA resin as a water-suspended polymer) ・Adhesive F: Rock Paint Co., Ltd., Rockbond J RU-40 / H-1 ​​(Main component: polyester polyurethane, curing agent: aliphatic polyisocyanate) • Adhesive G: Henkel LA4507 / LA5804 (Main component: styrene-acrylic polyol, curing agent: polyisocyanate) • Adhesive H: Henkel LW9112 (Hydroxylated adhesive containing ABS (acrylonitrile-styrene-butadiene) as a water-suspended polymer)

[0242] [Preparation of Transfer Film A] A heat seal layer with the following composition was applied to the non-corona-treated side of a PET film (manufactured by Toyobo Co., Ltd., 12 μm thick, corona-treated on one side) by gravure coating and dried to form a 5 μm thick heat seal layer. A main component of polyester (manufactured by Toyobo Co., Ltd., trade name: Byron® UR1700), a curing agent of XDI-based isocyanate (manufactured by Mitsui Chemicals, Inc., trade name: Takenate D110N), and an additive of nitrocellulose were mixed in a ratio of main component:curing agent:nitrocellulose (solid content mass ratio) of 1:1:1 to prepare an anchor coat agent. The anchor coat agent was applied to the heat seal layer by gravure coating and dried to form a 500 nm thick anchor coat layer. A silicon oxide vapor-deposited film with a thickness of 35 nm was formed on the anchor coat layer as an inorganic vapor-deposited film by physical vapor phase growth. A protective coating solution containing urethane resin and a silane coupling agent was applied to a silicon oxide vapor-deposited film by gravure coating and dried to form a protective layer with a thickness of 750 nm. In this way, a transfer film A having a layer structure of PET film / heat seal layer / anchor coat layer / silicon oxide vapor-deposited film / protective layer was obtained.

[0243] (Coating liquid for heat seal layer) ・Chemipearl (registered trademark) S120 (Mitsui Chemicals, Inc., aqueous ionomer emulsion, composition: metal salt of ethylene-methacrylic acid copolymer, self-emulsifying emulsion)

[0244] [Example 1] Adhesive A is applied to the protective layer surface of transfer film A, with a solid content application amount (solid content) of 2 g / m² after drying. ２ It was applied in this manner.

[0245] The adhesive A-coated surface of transfer film A and the glossy surface of paper substrate A were placed facing each other, and the two were bonded together and dried at 90°C for 5 seconds. In this way, an intermediate laminate having a layer structure of paper substrate A / adhesive A layer / protective layer / silicon oxide vapor-deposited film / anchor coat layer / heat seal layer / PET film was obtained. The PET film in the above intermediate laminate was peeled off to obtain barrier paper (barrier laminate).

[0246] [Example 2] The type of the adhesive was changed to Adhesive B, and a barrier paper (barrier laminate) was obtained in the same procedure as in Example 1, except that the coating amount of the solid content (solid content) after drying was 1 g / m ２ and the coating was applied so as to be.

[0247] [Comparative Example 1] A barrier paper (barrier laminate) was obtained in the same procedure as in Example 1, except that the type of the adhesive was changed to Adhesive C.

[0248] [Example 3] A barrier paper (barrier laminate) was obtained in the same procedure as in Example 1, except that the type of the adhesive was changed to Adhesive D.

[0249] [Example 4] A barrier paper (barrier laminate) was obtained in the same procedure as in Example 1, except that the type of the adhesive was changed to Adhesive E.

[0250] [Example 5] A barrier paper (barrier laminate) was obtained in the same procedure as in Example 1, except that the type of the paper base material was changed to Paper Base Material B.

[0251] [Example 6] A barrier paper (barrier laminate) was obtained in the same procedure as in Example 1, except that the type of the paper base material was changed to Paper Base Material C.

[0252] [Comparative Example 2] On the protective layer side of the transfer film A, Adhesive F was applied so that the coating amount of the solid content (solid content) after drying was 3 g / m ２ and then dried at 80°C for 35 seconds to form an Adhesive F layer. The Adhesive F layer formed on the transfer film A and the matte surface of the paper base material A were opposed to each other, and the two were bonded together to obtain an intermediate laminate having a layer structure of paper base material A / Adhesive F layer / protective layer / silicon oxide vapor deposition film / anchor coat layer / heat seal layer / PET film (reference transfer method). The PET film in the intermediate laminate was peeled off to obtain a barrier paper (barrier laminate).

[0253] [Comparative Example 3] The type of the adhesive was changed to Adhesive G, and the coating amount of the solid content (solid content) after drying was 2 g / m ２It was applied and dried so as to form an adhesive G layer, and a barrier paper (barrier laminate) was obtained in the same procedure as in Example 1 except that the adhesive G layer and the glossy surface of the paper base material A were opposed and the two were bonded together.

[0254] [Example 7] The type of the adhesive was changed to adhesive H, and a barrier paper (barrier laminate) was obtained in the same procedure as in Example 1 except that the coating amount (solid content) of the solid content after drying was 2 g / m ２ It was applied so as to obtain.

[0255] [Measurement of Martens hardness, etc. of the adhesive layer] For the adhesive layers of the barrier papers (barrier laminates) of the examples and comparative examples, the Martens hardness HM, the recovery rate η IT , the maximum load F ｍａｘ at the maximum indentation depth (penetration depth) h ｍａｘ were measured.

[0256] Specifically, it was measured using a surface film physical property tester (PICODENTOR HM-500, manufactured by Fisher Instruments Co., Ltd.), and a diamond indenter (Vickers indenter) with a face angle of 136° was used to push the diamond indenter into the adhesive layer. From the indentation load F and the indentation depth h (indentation depth), the Martens hardness, the recovery rate η ＩＴ , the maximum load F ｍａｘ at the maximum indentation depth (penetration depth) h ｍａｘ were obtained. The measurement of the Martens hardness was carried out at three or more points on the same plane, and was described as the arithmetic mean value of the values measured at three points with good reproducibility.

[0257] [Measurement of softening point of the adhesive layer] For the adhesive layers of the barrier papers (barrier laminates) of the examples and comparative examples, the softening point was measured. As the measuring device, nanoTA manufactured by Anasys Instruments was used, and as the thermal probe, PR-EX-AN2-300-5 manufactured by Anasys Instruments was used.

[0258] First, the following calibration was performed before measurement. Bruker's nanoTA Calibration Samples were prepared as standard samples. Polycaprolactone (softening point: 55°C), polyethylene (softening point: 116°C), and polyethylene terephthalate (softening point: 235°C), all with known softening points, were placed on the standard sample stand. Each standard sample was heated while a thermal probe was in contact with its surface. During heating, the thermal expansion directly beneath the thermal probe was measured, and a graph representing the deflection (displacement) against the voltage (potential) was obtained. The measurement conditions set on the instrument were as follows: Measurement start temperature: 0.1V Measurement end temperature: 10V Heating rate: 0.2V / sec Using the softening points of each standard sample, the graph representing the displacement of the thermal probe against the potential was converted into a graph representing the displacement against temperature. Calibration (n=3) was performed in the manner described above.

[0259] After calibration, the softening points of the adhesive layers of the barrier paper (barrier laminate) in the examples and comparative examples were measured. Measurements of the softening points were taken at five or more locations on the same plane, and the softening point was recorded as the arithmetic mean of the five values ​​measured with good reproducibility. However, the interval between each measurement point was at least 5 μm.

[0260] The measurement procedure involved first applying an adhesive similar to that used in the adhesive layer of the barrier paper (barrier laminate) in the examples and comparative examples to a PET substrate with a thickness of 25 μm, drying it, and creating an adhesive layer with a thickness of 100 μm. The adhesive layer was then fixed to a sample stage so that its surface was exposed. Next, a thermal probe was brought into contact with the surface of the adhesive layer, and while the thermal probe was in contact, the sample was heated under the following conditions to obtain a graph (thermal expansion curve) representing the displacement of the thermal probe with respect to temperature. Measurement start temperature: 40°C; Measurement end temperature: 300°C; Heating rate: 10°C / sec

[0261] If a peak was obtained in the thermal expansion curve, the temperature of that peak was considered the softening point. If multiple peaks were present in the obtained thermal expansion curve, the temperature of the peak that appeared on the lowest temperature side was considered the softening point. Thermal expansion curves in which a continuous decrease in displacement of 0.2V or more was measured from the maximum displacement were considered to have obtained a peak.

[0262] [Evaluation] <Gas barrier property evaluation> Test specimens were obtained by cutting out the barrier paper (barrier laminate) of the example and the barrier paper (barrier laminate) of the comparative example. The oxygen permeability (cc / (m)) of these test specimens was measured in a flat state without folding. ２ (day / atm) and water vapor transmission rate (g / m) ２ The properties of the test specimens were measured using the following method. These properties were also measured for specimens that had been folded into quarters and then returned to their original positions. The four-fold test specimens were prepared by first folding the specimen with the heat-sealed surface facing inward using a 2 kg roller (SA-1003-B, manufactured by Tester Sangyo Co., Ltd.), then second folding with the paper substrate facing inward using a 2 kg roller, and finally returning both folded sections to their original positions. The results are shown in Table 2 below (in Table 2, oxygen permeability is denoted as "OTR" and water vapor permeability as "WVTR").

[0263] Using an oxygen permeability measuring device (MOCON, OX-TRAN2 / 20), the test specimen was set so that the paper substrate side was on the oxygen supply side, and the oxygen permeability (OTR; unit: cc / (m³)) under conditions of 23°C and 90% RH was measured in accordance with JIS K7126. ２ The day and the ATM were measured.

[0264] Using a water vapor transmission rate measuring device (MOCON, PERMATRAN-w 3 / 33), the test specimen was set so that the paper substrate side was facing the water vapor supply side, and the water vapor transmission rate (WVTR; unit: g / m³) was measured in accordance with JIS K7129 at 40°C and 90% RH. ２ The day was measured.

[0265] <Recyclability Evaluation> The recyclability of the barrier laminates of Example and Comparative Example 1 was evaluated from the pulp recovery rate after re-disintegration. Specifically, first, a barrier laminate with a dry mass of 40 g was cut to a size of 25 mm x 25 mm to prepare test pieces. The prepared test pieces were placed in the container of a pulp disintegrator (manufactured by Kumagai Riki Kogyo Co., Ltd., conforming to JIS P8220:2012), 2000 ml of water was added, and the mixture was stirred at a rotation speed of 3000 rpm for 10 minutes to perform the disintegration treatment and obtain a pulp slurry. Next, the obtained pulp slurry was placed in the liquid input section of a flat screen (manufactured by Kumagai Riki Kogyo Co., Ltd., No. 2625) equipped with a screen plate with 6 cuts (slit width 0.15 mm), and refined in a water flow of 10 L / min. After drying the residue on the screen plate in an oven at 105°C, the mass was measured, and the pulp recovery rate was calculated using the following formula. The results are shown in Table 2 below (indicated as "Recyclability" in Table 2). (Recovery Rate) Pulp recovery rate = (Dry mass of barrier laminate before testing - Dry mass of residue) / Dry mass of barrier laminate before testing × 100 [%] (Appearance evaluation of residue) A: Only pulp balls remain on a part of the residue surface B: Paper adheres to the entire surface of the residue

[0266]

[0267]

[0268] As can be seen from the table above, in the example in which the adhesive layer interposed between the paper substrate and the barrier layer is a cured product of a hydrolyzable adhesive containing a water-suspendable polymer, and the Martens hardness and recovery rate of the adhesive layer are within the specified range, the decrease in oxygen permeability and water vapor permeability is relatively small even when folded into four and stress is applied, and furthermore, the recovery rate in the recyclability test was 80% or more, and the appearance evaluation was also good.

[0269] In contrast, the barrier laminate of Comparative Example 1, in which the Martens hardness and recovery rate of the adhesive layer were outside the specified range, showed a relatively large decrease in oxygen permeability when folded into four and subjected to stress. Furthermore, the barrier laminate of Comparative Example 2, in which the adhesive layer interposed between the paper substrate and the barrier layer was not made from a cured product of a water-suspendable polymer-containing hydrolyzable adhesive, had a recovery rate of less than 80% in the recyclability test. In addition, paper adhered to the entire surface of the residue, and the adhesive did not hydrolyze during the recycling test, resulting in it remaining in the residue containing a large amount of pulp. Moreover, the barrier laminate of Comparative Example 3, in which the recovery rate of the adhesive layer was within the specified range but the Martens hardness was outside the specified range, showed a relatively large decrease in oxygen permeability when folded into four and subjected to stress. Furthermore, the recovery rate in the recyclability test was less than 80%, and paper adhered to the entire surface of the residue. In addition, the adhesive did not hydrolyze during the recycling test, resulting in it remaining in the residue containing a large amount of pulp.

[0270] 1... Barrier laminate 2... Transfer film 10... Paper substrate 12... Printing layer 20... Adhesive layer 30... Barrier layer 32... Anchor coat layer 40... Heat seal layer 50... Support substrate (transfer substrate) 100, 200: Packaging 110, 210: Seal part

Claims

1. A barrier laminate comprising a paper substrate, an adhesive layer, a barrier layer, and a heat seal layer in this order in the thickness direction, wherein the adhesive layer is a cured product of a hydrolyzable adhesive containing at least a water-suspendable polymer, has a Martens hardness HM of 5 MPa or less, and has a recovery rate of 20% or more.

2. The amount of solids in the adhesive layer applied is 6 g / m². ２ The barrier laminate according to claim 1, which is as follows:

3. The barrier laminate according to claim 1, wherein the adhesive layer comprises an EVA-based resin.

4. The barrier laminate according to claim 1, wherein the pulp recovery rate of the paper substrate in accordance with the disintegration method of JIS P8220:2012 is 80% by mass or more.

5. A packaging body in which contents are packaged using a barrier laminate according to any one of claims 1 to 4, wherein at least a portion of the peripheral edge of the barrier laminate is heat-sealed with the heat-seal layers facing each other to seal the contents.

6. A packaging body in which contents are packaged using a barrier laminate according to any one of claims 1 to 4, wherein a second heat seal layer, identical or different from the heat seal layer, is laminated on the paper substrate of the barrier laminate, and the contents are sealed by overlapping and heat sealing the heat seal layer and the second heat seal layer at least a part of the peripheral edge of the barrier laminate.

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