Laminate, packaging material, packaging bag, and package

Abstract

Provided is a laminate comprising a gas barrier film layer, an adhesive layer and a sealant layer in this order. The adhesive layer is formed from a solvent-free adhesive, and the sealant layer comprises a composition that contains a polyolefin-based resin and a white pigment.

Description

Laminate, packaging material, packaging bag and packaging body

[0001] The present disclosure relates to a laminate, a packaging material, a packaging bag, and a packaging body.

[0002] As part of efforts to address environmental issues, packaging bags (e.g., flexible bags) made of plastic packaging materials are becoming more common. The packaging materials used in packaging bags are required to have various properties, such as strength, light blocking properties, concealment properties, water resistance, moisture resistance, gas barrier properties, and heat resistance, depending on the intended use. To improve these functions, typical packaging materials are made of a laminate in which multiple layers having various functions are stacked.

[0003] As a method for producing the laminate, a method of laminating two or more films with an adhesive is known. For example, when it is required to achieve both gas barrier properties for preventing deterioration of the contents and thermal adhesive properties for bag production, a laminate in which a gas barrier film and a sealant film are laminated with an adhesive is used.

[0004] In recent years, various efforts have been made to impart to packaging materials the ability to conceal the contents and the ability to block visible light, etc. For example, Patent Document 1 proposes a method of laminating a white ink layer on an information display print layer.

[0005] JP 2003-340965

[0006] In recent years, from the viewpoint of reducing the environmental impact, the use of a solvent-free adhesive as an adhesive for forming the laminate has been considered. However, the inventors of the present disclosure have found that when one of the films to be bonded using a solvent-free adhesive has the white ink layer, air bubbles significantly cause poor appearance.

[0007] Therefore, an object of one aspect of the present disclosure is to provide a laminate that uses a solvent-free adhesive, has excellent light-blocking properties and hiding power, and is also susceptible to poor appearance due to bubbles.

[0008] Although the reason for the occurrence of the above-mentioned poor appearance is unclear, it is presumed that the poor appearance is due to microvoids arising from gaps between pigments present within the white ink layer, i.e., the layer formed from the white ink. That is, the white ink layer formed to improve light-blocking and concealing properties contains a high concentration of pigment to ensure sufficient light-blocking and concealing properties. For example, to achieve a white ink layer lightness L* of 75 or more, it is usually necessary to set the ratio of the white pigment content to the binder resin content in the white ink (pigment / resin ratio) to a mass ratio of 3 or more. Therefore, many microvoids arising from gaps between pigments exist within the white ink layer. The air contained in these cavities is pushed out by the penetration of the adhesive applied to the white ink layer into the cavities. However, when a solventless adhesive is used as the adhesive, the film lamination process is performed without a step for drying the adhesive, so the pushed-out air remains within the laminate without being released to the outside. As a result, it is presumed that the trapped air manifests as air bubbles, resulting in the above-mentioned poor appearance.

[0009] As a result of intensive research based on the above speculation, the inventors of the present disclosure have found that by using a sealant layer containing a white pigment and a polyolefin-based resin instead of a white ink layer, it is possible to achieve both excellent light-blocking properties and excellent hiding properties while suppressing poor appearance.

[0010] Some aspects of the present disclosure have been made based on the above findings and provide the following [1] to

[11] .

[0011] [1] A laminate comprising a gas barrier film layer, an adhesive layer, and a sealant layer in this order, wherein the adhesive layer is a layer formed from a solventless adhesive, and the sealant layer is a layer made of a composition containing a polyolefin resin and a white pigment.

[0012] [2] The laminate according to [1] above, further comprising a printed layer formed from at least one type of ink, including a color ink other than a white ink, between the gas barrier film layer and the adhesive layer.

[0013] [3] The laminate according to [2] above, wherein the printed layer is a layer formed from a water-based ink.

[0014] [4] The laminate according to any one of the above [1] to [3], wherein the solvent-free adhesive is a two-component curing polyurethane adhesive.

[0015] [5] The laminate according to any one of [1] to [4] above, wherein the polyolefin resin is a polypropylene resin.

[0016] [6] The laminate according to any one of [1] to [5] above, wherein the lightness L* value of the sealant layer based on the color system specified in JIS Z8781-4 is 75 or more.

[0017] [7] A packaging material comprising the laminate according to any one of [1] to [6] above.

[0018] [8] A packaging bag made from the packaging material according to [7] above.

[0019] [9] The packaging bag according to the above [8], which is for boiling or retorting.

[0020]

[10] The packaging bag according to [8] or [9] above, wherein the amount of chloride ion migration measured and calculated under the following conditions is less than 1 μg / mL. Conditions for measuring and calculating the amount of chloride ion migration: A package containing 200 mL of water in the packaging bag is prepared, and the package is heat-treated at 121°C for 30 minutes. The water is removed from the package after the heat treatment, and the chloride ion content of the water is measured using an ion chromatogram, and the amount of chloride ion migration is calculated using the following formula: Amount of chloride ion migration (unit: μg / mL) = Chloride ion content of water after heat treatment (unit: μg / mL) - Chloride ion content of water before being placed in the packaging bag (unit: μg / mL).

[0021]

[11] A package comprising the packaging bag according to any one of [8] to

[10] above, and contents contained in the packaging bag.

[0022] According to the present disclosure, a laminate can be provided using a solvent-free adhesive that has excellent light-blocking and hiding properties and that is suppressed from having poor appearance due to bubbles.

[0023] Fig. 1 is a schematic cross-sectional view showing a first embodiment of a laminate according to the present disclosure, and Fig. 2 is a schematic cross-sectional view showing a second embodiment of a laminate according to the present disclosure.

[0024] Hereinafter, embodiments of the present disclosure will be described in detail, with reference to the drawings as needed. However, the present disclosure is not limited to the following embodiments.

[0025] In the present disclosure, a numerical range indicated using "to" indicates a range that includes the numerical values ​​written before and after "to" as the minimum and maximum values, respectively. Furthermore, unless specifically stated otherwise, the units of the numerical values ​​written before and after "to" are the same. In the numerical ranges described in stages in the present disclosure, the upper or lower limit of a numerical range in a certain stage may be replaced with the upper or lower limit of a numerical range in another stage. Furthermore, in the numerical ranges described in the present disclosure, the upper or lower limit of the numerical range may be replaced with a value shown in the examples. Furthermore, the upper and lower limits individually described can be combined in any way. Furthermore, "A or B" may include either A or B, or may include both.

[0026] Hereinafter, embodiments of the present disclosure will be described in detail, possibly with reference to the drawings. However, the present disclosure is not limited to the following embodiments. The laminate described below can be used, for example, as a packaging material for forming a packaging bag, but the use of the laminate is not limited thereto.

[0027] <Laminate> (First Embodiment) Fig. 1 is a schematic cross-sectional view showing a first embodiment of a laminate of the present disclosure. The laminate 10 of Fig. 1 includes, in this order, a gas barrier film layer 1, a printed layer 2, an adhesive layer S1, and a sealant layer 3. The printed layer 2 is a layer formed from at least one type of ink including colored inks other than white ink, the adhesive layer S1 is a layer formed from a solvent-free adhesive (hereinafter also referred to as a "solvent-free adhesive layer"), and the sealant layer 3 is a layer made of a composition containing a polyolefin resin and a white pigment (hereinafter also referred to as a "milky white polyolefin resin composition"). The thickness of the laminate 10 is, for example, 30 to 100 µm.

[0028] The laminate 10 can be obtained, for example, by forming a printed layer 2 on a gas barrier film that constitutes the gas barrier film layer 1, obtaining a printed gas barrier film consisting of the gas barrier film layer 1 and the printed layer 2, and then bonding the printed gas barrier film and a sealant film that constitutes the sealant layer 3 together via a solvent-free adhesive.

[0029] The laminate 10 has excellent light-blocking and concealing properties because it includes a sealant layer 3 (a layer made of a milky white polyolefin resin composition) instead of a white ink layer. For the same reason, poor appearance due to air bubbles is suppressed in the laminate 10. Furthermore, while the white ink layer can cause a solvent odor, the laminate 10 can reduce the solvent odor due to the white ink layer for the same reason.

[0030] Furthermore, according to studies by the inventors of the present disclosure, conventional laminates including the above-described white ink layer have a problem in that the interface between the printed layer and the white ink layer mixes, impairing the clarity of the printed layer as viewed from outside the laminate; however, in laminate 10, such a problem is unlikely to occur because no white ink layer is laminated on printed layer 2. In other words, in laminate 10, the color of the printed layer is easily visible clearly. Note that "chroma C*" is defined as a method for quantifying the degree of clarity, and is calculated by the following formula using a* and b* in the color system (L*a*b* color system) specified in JIS Z8781-4: a* and b* indicate the direction of color, with +a* being red, -a* being green, +b* being yellow, and -b* being blue. In each direction, the larger the absolute value, the more vivid the color becomes, and as it approaches 0, the color becomes dull. As the absolute value of saturation C* increases, the vividness improves, and as the value decreases, the color becomes dull and loses vividness.

[0031] Furthermore, in conventional laminates having the above-mentioned white ink layer, in order to obtain the required light-blocking and hiding properties, it is necessary to apply the white ink layer thickly or in multiple layers, slow down the processing speed for drying, or increase the number of coating units for multiple layers, resulting in the problem that it is difficult to achieve sufficient productivity, whereas the sealant layer 3 can be easily formed into a thick film, and therefore the above-mentioned problems do not occur in the laminate 10. In other words, the laminate 10 can also be excellent in productivity.

[0032] Each layer constituting the laminate 10 will now be described.

[0033] [Gas barrier film layer] The gas barrier film layer 1 is made of a gas barrier film including a base film and a gas barrier layer. That is, the gas barrier film layer 1 has a laminated structure in which the gas barrier layer is laminated on the base film. Although not shown, the gas barrier layer may be provided on the printed layer 2 side of the base film, or on the opposite side from the printed layer 2. The gas barrier layer provided on the base film may have a single-layer structure or a multi-layer structure.

[0034] The gas barrier film layer 1 may be transparent so that a pattern can be displayed by the printing layer. Here, the film being transparent means that the total light transmittance of the film is 85% or more as measured in accordance with JIS K7361-1:1997 using a color and turbidity simultaneous measuring device ("COH400" manufactured by Nippon Denshoku Industries Co., Ltd.).

[0035] The substrate film may be a known resin film used for packaging bags on which the printed layer 2 can be formed. The substrate film is, for example, a stretched film such as a biaxially stretched resin film. Examples of resins that make up the resin film include polyesters such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate, polyamides such as nylon, polypropylene, polystyrene, polyimide, polyvinyl alcohol, polyvinyl chloride, and ethylene-vinyl alcohol copolymers. As the resin film, a composite film in which two or more types of films are laminated can be used.

[0036] The thickness of the substrate film is, for example, 4 to 60 μm.

[0037] The gas barrier layer is a layer that has barrier properties against at least one type of gas, such as oxygen gas or water vapor. The gas barrier layer may be a layer that has oxygen barrier properties, or may be a layer that has water vapor barrier properties. Here, the term "a layer has oxygen barrier properties" means that the layer has an oxygen transmission rate (OTR, unit: cc / m) measured under conditions of 25°C and 80% relative humidity using an oxygen transmission rate measuring device (OX-TRAN2 / 21 model manufactured by MOCON Corporation) in accordance with JIS K7126-2 (2006). ２ / day / atm) is 2cc / m ２ The layer having water vapor barrier properties means that the water vapor transmission rate (WVTR, unit: g / m) is measured at 40°C and 90% relative humidity using a water vapor transmission rate measuring device (DELTAPERM manufactured by Technolox) in accordance with JIS K7129-5 (2016). ２ / day) is 1.0 g / m ２ The gas barrier layer may have not only gas barrier properties against oxygen gas and water vapor but also aroma retention properties for the contents.

[0038] The gas barrier layer may be composed of, for example, one or more layers selected from the group consisting of an inorganic vapor deposition layer and a resin coating layer made of a barrier resin.

[0039] The inorganic vapor deposition layer is a layer formed by vapor deposition of an inorganic material such as a metal oxide. Examples of metal oxides include silicon oxide and aluminum oxide. The metal oxide is preferably aluminum oxide. Examples of methods for forming the inorganic vapor deposition layer include physical vapor deposition methods (PVD methods) such as vacuum deposition, sputtering, and ion plating, and chemical vapor deposition methods (CVD methods) such as plasma-enhanced chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition.

[0040] The thickness of the inorganic vapor-deposited layer is preferably 1 to 200 nm. When the inorganic vapor-deposited layer is a vapor-deposited layer of silicon oxide or aluminum oxide (alumina), the thickness of the inorganic vapor-deposited layer is preferably 1 to 100 nm, more preferably 10 to 50 nm, and even more preferably 20 to 30 nm.

[0041] The resin coating layer is, for example, a dried coating film of a water-soluble polymer having a hydroxyl group. Examples of water-soluble polymers having a hydroxyl group include polyvinyl alcohol, polyvinyl acetate, and ethylene-vinyl acetate copolymer. Commercially available water-soluble polymers may be used. Examples of commercially available products include the Kuraray Poval, Elvanol, and Exeval series manufactured by Kuraray Co., Ltd., and the Gohsenol and Soarnol series manufactured by Mitsubishi Chemical Corporation.

[0042] The gas barrier layer may be a layer containing any one selected from the group consisting of a condensate of a metal alkoxide, a condensate of a hydrolysis product of a metal alkoxide, and a condensate of an alkoxysilyl alkyl isocyanurate.

[0043] The metal alkoxide is, for example, a silane (alkoxysilane) having an alkoxy group, such as tetraalkoxysilane, alkyltrialkoxysilane, dialkyldialkoxysilane, etc. The alkoxy group is, for example, a methoxy group, an ethoxy group, or an ethoxymethoxy group.

[0044] The alkoxysilylalkyl isocyanurate is, for example, 1,3,5-tris(3-trialkoxysilylalkyl) isocyanurate.

[0045] The gas barrier layer may be a layer containing a polycarboxylic acid polymer or a hydrolysis product of a metal oxide and a phosphorus compound.

[0046] The hydrolysis product of a metal oxide and a phosphorus compound has a structure in which metal oxide particles are bonded to each other via phosphorus atoms derived from the phosphorus compound. Examples of phosphorus compounds include phosphoric acid, polyphosphoric acid, phosphorous acid, phosphonic acid, and derivatives thereof. The phosphorus compound has one or more reaction sites that react with the metal oxide. The reaction site is a bond between a phosphorus atom and an oxygen atom, or a bond between a phosphorus atom and a halogen atom. Metal atoms constituting the metal oxide include, for example, Mg, Ca, Zn, Al, Si, Ti, and Zr, and have a valence of two or more. The metal oxide is produced by hydrolyzing and condensing a metal compound having a hydrolyzable functional group. The method for hydrolyzing and condensing the metal compound is a liquid-phase synthesis method such as a sol-gel method. The metal oxide is in the form of fine particles, and may have, for example, a spherical, flat, polyhedral, fibrous, or acicular shape. From the viewpoint of improving gas barrier properties and hot water resistance, the metal oxide particles are preferably fibrous or acicular.

[0047] The gas barrier layer may be composed of a layer containing one or more of the above-mentioned materials, or may include two or more layers each containing one or more of the above-mentioned materials.

[0048] The thickness (total thickness) of the gas barrier layer is, for example, 0.01 to 5 μm.

[0049] The gas barrier film layer 1 may include a primer layer between the gas barrier layer and the base film. The gas barrier film layer 1 may have a laminate structure in which a base film, a primer layer, an inorganic vapor deposition layer, and a resin coating layer made of a barrier resin are laminated in this order. The primer layer may contain a reaction product of either a trialkoxysilane or a trialkoxysilane hydrolysis product with an acrylic polyol and an isocyanate compound, or may contain a reaction product of an acrylic polyol and an isocyanate compound.

[0050] Trialkoxysilanes are represented by the general formula R １ Si(OR ２ ) ３ It is shown by R １represents an alkyl group, a vinyl group, an alkyl group containing an isocyanate group, an alkyl group containing a glycidoxy group, or an alkyl group having an epoxy group. １ The alkyl group contained in R may be a linear alkyl group, a branched alkyl group, or a cyclic alkyl group. １ can be changed appropriately depending on the materials constituting the base film and the gas barrier layer. ２ is a hydrolyzable alkoxy group such as a methoxy group, an ethoxy group, or an ethoxymethoxy group. The hydrolysis product of a trialkoxysilane can be obtained, for example, by adding an acid or an alkali to a trialkoxysilane to hydrolyze the trialkoxysilane.

[0051] Specific examples of trialkoxysilanes include ethyltrimethoxysilane, vinyltrimethoxysilane, isocyanatepropyltriethoxysilane, γ-isocyanatepropyltrimethoxysilane, glycidoxypropyltrimethoxysilane, and epoxycyclohexylethyltrimethoxysilane. Among these, isocyanatepropyltriethoxysilane and γ-isocyanatepropyltrimethoxysilane, which contain an isocyanate group, are preferred. Also preferred are glycidoxytrimethoxysilane, which contains a glycidoxy group, and epoxycyclohexylethyltrimethoxysilane, which contains an epoxy group. The trialkoxysilane is, for example, one or a combination of two or more selected from the above-mentioned compounds.

[0052] The acrylic polyol is, for example, a homopolymer of an acrylic acid derivative monomer, or a copolymer of an acrylic acid derivative monomer and styrene or the like. The copolymer of the acrylic acid derivative monomer may contain a compound having a terminal hydroxyl group and reacting with an isocyanate group of an isocyanate compound. The acrylic acid derivative monomer is, for example, ethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, or hydroxybutyl methacrylate. The acrylic polyol is, for example, one or a combination of two or more selected from the above-mentioned compounds.

[0053] The isocyanate compound is, for example, an aromatic isocyanate compound or an aliphatic isocyanate compound. The isocyanate compound is, for example, a polymer of an aromatic isocyanate compound or an aliphatic isocyanate compound with a polyol. The isocyanate compound is a derivative produced from a polymer of an aromatic isocyanate compound, an aliphatic isocyanate compound, and a polyol. The isocyanate compound is, for example, one or a combination of two or more selected from the above-mentioned compounds.

[0054] Commercially available products may be used as the gas barrier film constituting the gas barrier film layer 1. Examples of commercially available products include the "GL BARRIER" series manufactured by TOPPAN Corporation, the "Barrierox" series manufactured by Toray Advanced Film Co., Ltd., the "Max Barrier" series manufactured by Mitsui Chemicals Tocello, and the "Tech Barrier" series manufactured by Mitsubishi Chemical Corporation.

[0055] The thickness of the gas barrier film layer 1 is, for example, 4 to 60 μm.

[0056] [Printed Layer] The printed layer 2 is a layer formed by printing ink, and specifically, is formed from at least one type of ink including colored inks other than white ink. Here, in this disclosure, inks including a pigment and a binder resin are referred to as colored inks, and colored inks including only white pigments are referred to as white inks. Therefore, the printed layer 2 includes at least a pigment other than white pigment and a binder resin. Note that the ink used as a printing material and the ink included in the printed layer may have different compositions due to the influence of layer formation processes such as drying and curing, but for convenience, in this disclosure, these will be collectively referred to as inks.

[0057] As the color inks other than the white ink, known color inks (for example, red ink, yellow ink, indigo ink, black ink) can be used. The type of pigment contained in the color inks other than the white ink may be determined appropriately depending on the color to be expressed. For example, inorganic pigments or organic pigments may be used as the pigments. Examples of inorganic pigments include carbon black (ink pigment). Examples of organic pigments include azo pigments, phthalocyanine pigments, dioxazine pigments, quinacridone pigments, isoindolinone pigments, and dye lake pigments. A combination of multiple pigments may be used as the pigment.

[0058] Examples of binder resins contained in colored inks other than white ink include alkyd resins, phenolic resins, maleic acid resins, natural resins, hydrocarbon resins, polyvinyl chloride resins, polyacetic acid resins, polystyrene resins, polyvinyl butyral resins, acrylic or methacrylic resins, polyamide resins, polyester resins, polyurethane resins, epoxy resins, urea resins, melamine resins, nitrocellulose, ethyl cellulose, etc. These may be used alone or in combination of two or more.

[0059] The ratio of the pigment content to the binder resin content (pigment / resin ratio) in color inks other than white ink is, for example, 1.6 or less by mass, and preferably 0.5 to 1.6. A better appearance is likely to be obtained when the mass ratio (pigment / resin ratio) is 1.6 or less.

[0060] The ink forming the printed layer 2 may consist solely of colored inks other than white ink, or may consist of colored inks other than white ink and colorless ink (ink not containing pigment). The ink forming the printed layer 2 may contain white ink containing a smaller amount of pigment than white ink used for the purpose of improving light-blocking and hiding properties (for example, white ink in which the ratio of the pigment content to the binder resin content (pigment / resin ratio) is 0.5 to 1.6 by mass). However, from the viewpoint of reducing minute voids caused by gaps between pigments formed in the printed layer and obtaining a better appearance, it is preferable that the ink not contain white ink.

[0061] The ink forming the printed layer 2 may be either an aqueous ink or an oil-based ink. However, from the viewpoint of environmental protection, an aqueous ink is preferred. From the viewpoint of increasing productivity and further suppressing appearance defects, an oil-based ink is preferred. Furthermore, since aqueous inks have a relatively lower solvent odor than oil-based inks, using an aqueous ink to form the printed layer 2 can reduce the solvent odor associated with the printed layer 2. When forming the printed layer of a conventional laminate including the white ink layer described above using an aqueous ink, from the viewpoint of productivity, it is common to form the white ink layer using an aqueous ink layer and to perform the drying of the ink for forming the printed layer and the drying of the ink for forming the white ink layer successively. However, when an aqueous ink is used to form the printed layer, moisture is likely to remain in the printed layer and the white ink layer due to the poor drying properties of the aqueous ink. This tendency is particularly pronounced when the white ink layer is applied thickly or in multiple layers to enhance light-blocking and hiding properties. On the other hand, polyurethane adhesives commonly used as solventless adhesives contain polyisocyanate, and when the polyisocyanate in the adhesive reacts with the moisture, carbon dioxide is generated, which is observed as bubbles. In other words, when a white ink layer and a solventless adhesive layer are laminated, using aqueous ink to form the printed layer makes poor appearance more likely. In contrast, in this embodiment, there is no need to provide a white ink layer, so even if the printed layer is formed from aqueous ink, the aqueous ink can be dried well, resulting in an excellent appearance.

[0062] When the ink is oil-based, a mixture of polyurethane resin and vinyl chloride-vinyl acetate copolymer resin may be used as the binder resin from the viewpoint of heat resistance. This binder resin is suitable for use in oil-based inks for gravure printing (oil-based gravure inks).

[0063] When the ink is an aqueous ink, an aqueous binder resin may be used as the binder resin. Examples of the aqueous binder resin include emulsion-type binder resins, colloidal dispersion-type binder resins, and water-soluble binder resins. Examples of the aqueous binder resin include acrylic resins, polyester resins, urethane acrylic resins, styrene acrylic resins, and styrene-maleic acid resins, as well as water-soluble polyamide resins, aqueous polyester resins, and aqueous polyurethane resins.

[0064] A solvent may be used when preparing the ink, that is, the ink may contain a solvent.

[0065] When the ink is an oil-based ink, examples of the solvent that can be used appropriately include alcohol-based organic solvents such as methanol, ethanol, n-propanol, and isopropanol; ketone-based organic solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ester-based organic solvents such as methyl acetate and ethyl acetate; aliphatic hydrocarbon-based organic solvents such as n-hexane, n-heptane, and n-octane; alicyclic hydrocarbon-based organic solvents such as cyclohexane, methylcyclohexane, and cycloheptane; and aromatic hydrocarbon-based organic solvents such as toluene.

[0066] When the ink is an aqueous ink, an aqueous solvent containing water can be used as the solvent. Examples of aqueous solvents include lower alcohols, polyhydric alcohols, and their alkyl ethers or alkyl esters. Specific examples of aqueous solvents include lower alcohols such as methanol, ethanol, normal propanol, and isopropanol, polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, and glycerin, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol acetate, diethylene glycol monomethyl ether, and dipropylene glycol.

[0067] The ink may contain, as necessary, one or more additives such as plasticizers, stabilizers, antioxidants, light stabilizers, ultraviolet absorbers, curing agents, crosslinking agents, lubricants, antistatic agents, and fillers.

[0068] The printing layer 2 may be a layer that displays a pattern such as letters, figures, symbols, patterns, etc. There are no particular limitations on the type of pattern that can be displayed by the printing layer, and the type of ink to be used may be determined appropriately depending on the type of pattern that can be displayed by the printing layer.

[0069] The thickness of the printed layer 2 is, for example, 0.2 to 8 μm.

[0070] The printing layer 2 can be formed by a printing method such as gravure printing, letterpress printing, screen printing, transfer printing, or flexographic printing.

[0071] [Adhesive Layer] The adhesive layer S1 is a layer formed from a solvent-free adhesive (solvent-free adhesive layer). Here, a solvent-free adhesive refers to an adhesive that does not substantially contain solvents (organic solvents and water) (the solvent content is 0.5% by mass or less). Since solvent-free adhesives do not substantially contain solvents, they have the advantage of having a low environmental impact in the manufacturing process and can be applied more thinly than solvent-based adhesives. The fact that the adhesive layer S1 is a layer formed from a solvent-free adhesive rather than a layer formed from a solvent-based adhesive can be confirmed, for example, by analysis using Fourier transform infrared spectroscopy.

[0072] Examples of solvent-free adhesives include polyurethane adhesives. The polyurethane adhesive may be a one-component curing type or a two-component curing type, but is preferably a two-component curing type. When the solvent-free adhesive is a two-component curing polyurethane adhesive, the appearance tends to be more excellent.

[0073] The two-component curing polyurethane adhesive contains a base agent and a curing agent. Examples of the base agent include polyester polyol, polyether polyol, acrylic polyol, polyether ester polyol, and polyurethane polyol. Examples of the curing agent include a polyisocyanate compound having two or more functionalities. The polyisocyanate compound may be an aliphatic polyisocyanate, an aromatic polyisocyanate, or a mixture thereof.

[0074] The polyester polyol is, for example, an ester reaction product of a polycarboxylic acid, a dialkyl ester of a polycarboxylic acid, or a mixture thereof with a glycol-based compound. Examples of polycarboxylic acids include succinic acid, glutaric acid, isophthalic acid, terephthalic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, and dimer acid. Examples of glycol-based solvents include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butylene glycol, neopentyl glycol, and 1,6-hexanediol.

[0075] Polyether polyols are polymers of, for example, oxirane compounds and low-molecular-weight polyols. Examples of oxirane compounds include ethylene oxide, propylene oxide, butylene oxide, and tetrahydrofuran. Examples of low-molecular-weight polyols include water, ethylene glycol, propylene glycol, trimethylolpropane, and glycerin.

[0076] The polyetherester polyol is, for example, an ester reaction product of a polycarboxylic acid, a dialkyl ester of a polycarboxylic acid, or a mixture thereof with a polyether polyol.

[0077] Polyurethane polyols are, for example, the reaction product of polyester polyols, polyether polyols, polyetherester polyols, or mixtures thereof, with polyisocyanate monomers.

[0078] The aliphatic polyisocyanate and aromatic polyisocyanate may be a polyisocyanate monomer, a polyisocyanate derivative, or a polyisocyanate-terminated prepolymer.

[0079] Examples of polyisocyanate monomers that are aliphatic polyisocyanates include tetramethylene diisocyanate, isopropylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate, 1,3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, lysine diisocyanate, and isophorone diisocyanate.

[0080] Examples of the polyisocyanate monomer that is an aromatic polyisocyanate include tolylene diisocyanate, phenylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, and tetramethylxylylene diisocyanate.

[0081] The polyisocyanate derivative is, for example, an isocyanurate derived from a polyisocyanate monomer.

[0082] The polyisocyanate-terminated prepolymer may be a bifunctional polyisocyanate containing a terminal isocyanate group obtained by reacting a polyisocyanate monomer with a bifunctional polyol compound such as polypropylene glycol, or may be a multifunctional polyisocyanate containing a terminal isocyanate group obtained by reacting a polyisocyanate monomer with a trifunctional or higher polyol compound such as trimethylolpropane.

[0083] The solvent-free adhesive reacts with heat or the like (for example, the hydroxyl groups of the base agent react with the isocyanate groups of the curing agent) to harden, thereby forming the adhesive layer S1. The adhesive layer S1 thus formed contains a cured product of the solvent-free adhesive. The coating amount of the solvent-free adhesive is, for example, 0.5 to 5.0 g / m ２ is.

[0084] The thickness of the adhesive layer S1 is, for example, 0.3 to 5.0 μm.

[0085] [Sealant Layer] The sealant layer 3 is made of a composition containing a polyolefin resin and a white pigment (a milky white polyolefin resin composition). The sealant layer 3 is a layer for heat sealing when the laminate 10 is molded into a packaging bag or the like, and has thermal adhesive properties.

[0086] Examples of polyolefin resins include ethylene resins, polypropylene resins, propylene resins, ethylene-propylene copolymers, ethylene-α,β-unsaturated carboxylic acid copolymers, esters of ethylene-α,β-unsaturated carboxylic acid copolymers, acid anhydride-modified polyolefins, and blends of two or more of these. The ethylene-propylene copolymer may be a random copolymer or a block copolymer. Among these, polypropylene resins are particularly preferred because they have excellent thermal adhesiveness, heat resistance, and oil resistance.

[0087] The ethylene resin is, for example, low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), linear low density polyethylene (L.LDPE) or ethylene-α-olefin copolymer.

[0088] The polypropylene-based resin is, for example, homopolypropylene, block polypropylene, or random polypropylene.

[0089] The propylene-based resin is, for example, a propylene-α-olefin copolymer. From the viewpoint of impact resistance, it is desirable that the polyolefin-based resin contains a propylene-based copolymer resin. In particular, when the polyolefin-based resin contains an ethylene-propylene copolymer, impact resistance can be particularly improved.

[0090] The ethylene-α,β-unsaturated carboxylic acid copolymer is, for example, an ethylene-acrylic acid copolymer or an ethylene-methacrylic acid copolymer.

[0091] The acid anhydride-modified polyolefin is, for example, an ethylene-maleic anhydride graft copolymer, or a terpolymer such as ethylene-ethyl acrylate-maleic anhydride.

[0092] Examples of materials constituting the white pigment include inorganic oxides such as titanium oxide, alumina, mica, lead oxide (white lead), zinc oxide, calcium carbonate, barium carbonate, barium sulfate, kaolin, potassium titanate, talc, magnesium hydroxide, natural silicic acid, and synthetic silicic acid (white carbon). Among these, pigments containing titanium oxide are preferably used from the viewpoints of hiding power and dispersibility upon addition. Titanium oxide may be of the rutile type or the anatase type. The surface of the pigment containing titanium oxide may be treated with a metal oxide such as aluminum (Al) or silica (Si). The average particle size of the white pigment can be selected within a range that does not interfere with the objectives of the present disclosure.

[0093] From the viewpoint of thermal adhesion, the content of the polyolefin resin may be 90% by mass or more, 92% by mass or more, or 94% by mass or more, based on the total mass of the sealant layer (total mass of the milky polyolefin resin composition). From the viewpoint of light-blocking property and concealing property, the content of the polyolefin resin may be 97% by mass or less, 96% by mass or less, or 95% by mass or less, based on the total mass of the sealant layer. From these viewpoints, the content of the polyolefin resin may be 90 to 97% by mass, based on the total mass of the sealant layer.

[0094] From the viewpoints of light-blocking properties and concealing properties, the content of the white pigment may be 3% by mass or more, 4% by mass or more, or 5% by mass or more, based on the total mass of the sealant layer (total mass of the milky-white polyolefin resin composition). From the viewpoint of thermal adhesion, the content of the white pigment may be 10% by mass or less, 9% by mass or less, 8% by mass or less, or 6% by mass or less, based on the total mass of the sealant layer. From these viewpoints, the content of the white pigment may be 3 to 10% by mass or 3 to 9% by mass, based on the total mass of the sealant layer.

[0095] The ratio of the content of the white pigment to the content of the polyolefin resin (pigment / resin ratio) may be 0.04 to 0.1, 0.04 to 0.08, or 0.05 to 0.06, in mass ratio.

[0096] The sealant layer 3 may contain other additives as needed, such as antioxidants, slip agents, antiblocking agents, and weather resistance agents.

[0097] The sealant layer 3 may have a single-layer structure or a multi-layer structure. When the sealant layer has a multi-layer structure, all layers are layers made of a composition containing a polyolefin-based resin, and at least one of the layers is made of a milky polyolefin-based resin composition. The layer made of the milky polyolefin-based resin composition is preferably located on the gas barrier film layer 1 side (printed layer 2 side). Furthermore, for example, when the sealant layer 3 has a three-layer structure consisting of an outer layer / an intermediate layer / an outer layer, it is preferable that the intermediate layer is a layer made of a milky polyolefin-based resin composition. The polyolefin-based resins used in each layer may be the same or different. When the sealant layer has a structure of two or more layers, it is preferable that the thickness of each layer making up the sealant layer is 5 μm or more.

[0098] The thickness of the sealant layer 3 is not particularly limited and can be appropriately set depending on the desired properties. The thickness of the sealant layer 3 may be, for example, 15 to 200 μm, 30 to 200 μm, or 50 to 200 μm. By increasing the thickness of the sealant layer 3, it is possible to ensure sufficient hiding power and light-blocking properties while keeping the concentration of the white pigment low.

[0099] From the viewpoint of achieving superior light-blocking properties and concealing properties, the lightness L* value of the sealant layer 3 is preferably 75 or more, more preferably 80 or more, and particularly preferably 85 or more. The lightness L* value of the sealant layer 3 is 100 or less, and may be 95 or less, or 90 or less. The lightness L* value of the sealant layer 3 is a value based on the color system specified in JIS Z8781-4. The lightness L* value of the sealant layer 3 can be adjusted by the content of the white pigment in the sealant layer 3.

[0100] The sealant layer 3 may be a layer composed of one or more types of sealant film. The sealant film may be, for example, a non-stretched resin film. The method for forming the sealant film is not particularly limited, and various known methods can be used. However, from the viewpoint of preventing the formation of minute voids resulting from gaps between pigments, melt molding methods such as inflation and T-die extrusion are preferably used. That is, the sealant layer 3 is preferably a layer composed of a film formed by melt molding of a milky white polyolefin resin composition. When forming the sealant film, a masterbatch in which a white pigment is pre-kneaded into a polyolefin resin may be used. The white pigment concentration of the masterbatch may be, for example, about 40 to 70% by mass. When using a masterbatch, the masterbatch and polyolefin resin may be kneaded together to obtain a desired blend ratio.

[0101] Second Embodiment Fig. 2 is a schematic cross-sectional view showing a second embodiment of a laminate of the present disclosure. The laminate 20 shown in Fig. 2 includes a base film layer 4 and an adhesive layer S2 (second adhesive layer) in addition to a gas barrier film layer 1, a printed layer 2, an adhesive layer S1 (first adhesive layer), and a sealant layer 3. The base film layer 4 is disposed between the printed layer 2 and the sealant layer 3, with the adhesive layer S1 and the adhesive layer S2 interposed therebetween.

[0102] The adhesive layer S2 is formed by curing a solvent-free adhesive similar to the above-described adhesive layer S1. The solvent-free adhesive forming the adhesive layer S1 and the solvent-free adhesive forming the adhesive layer S2 may be the same type or different types.

[0103] When the thickness of the base film layer 4 is 4 to 25 μm, the thickness of the printed layer 2 is preferably 0.5 to 3 μm, and when the thickness of the base film layer 4 is 25 to 60 μm, the thickness of the printed layer 2 is preferably 1 to 8 μm. In the laminate shown in Fig. 2, the base film layer 4 is the outermost layer, and if the base film layer 4 is thicker than the printed layer 2, transparency will be poor and the printed layer 2 will be difficult to see.

[0104] If the adhesive layers S1, S2 are too thin, the adhesiveness will be weak, and if the adhesive layers S1, S2 are too thick, the adhesive in the adhesive layers may seep into the printed layer 2, so it is preferable that the thickness of the adhesive layers S1, S2 is approximately the same as the thickness of the printed layer 2. Specifically, the difference between the thickness of the adhesive layer S1 or S2 and the thickness of the printed layer 2 (thickness of the adhesive layer S1 or S2 - thickness of the printed layer 2) is preferably 0 to 4 μm.

[0105] The base film layer 4 is a layer made of a base film. The type of base film is not particularly limited, and for example, the gas barrier film or base film constituting the gas barrier film layer 1 described above can be used.

[0106] The thickness of the laminate 20 is, for example, 40 to 150 μm.

[0107] Like the laminate 10, the laminate 20 has a sealant layer 3 instead of a white ink layer, and therefore has excellent light-blocking and hiding properties, and is a laminate in which poor appearance due to air bubbles is suppressed.

[0108] Although the first and second embodiments of the laminate of the present disclosure have been described above, the laminate of the present disclosure is not limited to the above embodiments.

[0109] For example, the laminate may or may not include a printed layer. When the laminate includes a printed layer, the printed layer may be located between the gas barrier film layer and the adhesive layer, or may be located in another position.

[0110] The laminate may further include one or more other layers (e.g., films) to impart functions such as mechanical strength required of the packaging bag. The location at which the other layers are provided is not particularly limited. For example, the other layers may be provided between the gas barrier film layer 1 and the printing layer 2, or between the printing layer 2 and the adhesive layer S1. That is, the gas barrier film layer and the printing layer may or may not be adjacent to each other. Similarly, the printing layer and the adhesive layer (solventless adhesive layer) may or may not be adjacent to each other.

[0111] The laminate may include a white ink layer to the extent that the effects of the present invention are not impaired. For example, the laminate may include a white ink layer in a position that is not adjacent to the solventless adhesive layer. The ratio of the white pigment content to the binder resin content in the white ink layer (pigment / resin ratio) is preferably, for example, less than 3 by mass. The binder resin for the white ink layer may be any of the binder resins exemplified for use in the printing layer. The white pigment may be any of the white pigments exemplified for use in the sealant layer. The thickness of the white ink layer is, for example, 1 to 5 μm. The white ink layer may be formed in the same manner as the printing layer.

[0112] The laminate of the present disclosure can be suitably used to form a packaging bag (e.g., a flexible bag) for packaging contents. The laminate including the sealant layer can be used as a packaging material as it is.

[0113] The lightness L* value of the laminate of the present disclosure is preferably 75 or more, more preferably 80 or more, and particularly preferably 85 or more, from the viewpoint of achieving superior light-blocking and concealing properties. The lightness L* value of the laminate is 100 or less, and may be 95 or less, or 90 or less. The lightness L* value of the laminate is a value based on the color system specified in JIS Z8781-4, and is measured from the sealant layer side. The lightness L* value of the laminate can be adjusted by, for example, the content of the white pigment in the sealant layer.

[0114] However, in packaging materials that include a white ink layer as a light-blocking means, such as conventional packaging materials, the thickness of the white ink layer tends to be large due to the light-blocking properties (for example, a white ink layer that is thicker than a pattern ink is formed over a wide area). In particular, packaging bags manufactured from packaging materials with a white ink layer derived from oil-based ink may emit a residual solvent odor from the contents, while packaging bags manufactured from packaging materials with a white ink layer derived from water-based ink may have chloride ions in the white ink migrate to the contents, causing a chlorine odor from the contents. In contrast, the laminate of the present disclosure not only reduces the solvent odor derived from the white ink layer, but also tends to reduce the migration of chloride ions from the packaging bag to the contents. For example, in the laminate of the present disclosure, the amount of chloride ion migration measured and calculated under the following conditions may be less than 1 μg / mL.

[0115] Conditions for measuring and calculating the amount of chloride ion migration: A packaging bag is obtained by laminating the sealant layers of the laminate of the present disclosure together and processing them into a bag. 200 mL of water is placed in the resulting packaging bag to obtain a package. The resulting package is heat-treated at 121°C for 30 minutes. Water is removed from the package after the heat treatment, and the chloride ion content of the water is measured using an ion chromatogram, and the amount of chloride ion migration is calculated using the following formula: Amount of chloride ion migration (unit: μg / mL) = Chloride ion content of water after heat treatment (unit: μg / mL) - Chloride ion content of water before being placed in a package (unit: μg / mL).

[0116] The packaging bag may be obtained, for example, by preparing two sheets of the laminate of the present disclosure, each measuring 100 to 300 mm long and 150 to 400 mm wide, placing the sealant layers of the two sheets face each other so that their four sides overlap, and heat-sealing three of the four sides. The package may also be obtained by placing 200 mL of water in the packaging bag prepared as described above and heat-sealing the opening of the packaging bag. The seal width of the packaging bag and package may be, for example, 3 to 20 mm.

[0117] From the viewpoint of further reducing the effect of the packaging on the odor of the contents, the amount of chloride ion migration measured and calculated under the above conditions may be 0.5 μg / mL or less, 0.3 μg / mL or less, or 0 μg / mL.

[0118] <Packaging Material> Another embodiment of the present disclosure is a packaging material (e.g., packaging film) including the laminate of the present disclosure described above. The packaging material includes, for example, a sealant layer as the outermost layer. The packaging material may consist solely of the laminate of the present disclosure described above (e.g., laminate 10 or 20), or may be a processed version of the laminate.

[0119] The packaging material of this embodiment is suitable for use in forming a packaging bag (e.g., a flexible bag) for packaging contents. Specifically, for example, a packaging bag can be manufactured by bonding the sealant layers of a pair of packaging materials together and forming a bag. Alternatively, for example, a packaging bag can be manufactured by folding one piece of packaging material so that the sealant layer faces each other and then forming a bag.

[0120] Even in the packaging material of this embodiment, the amount of chloride ion migration measured and calculated under the above conditions may be less than 1 μg / mL. From the viewpoint of further reducing the impact of packaging on the odor of the contents, the amount of chloride ion migration measured and calculated under the above conditions may be 0.5 μg / mL or less, 0.3 μg / mL or less, or 0 μg / mL. In measuring the amount of chloride ion migration in the packaging material, the term "laminate" in the above conditions shall be read as "packaging material."

[0121] <Packaging Bag> Another embodiment of the present disclosure is a packaging bag produced by manufacturing the packaging material of the above embodiment. The packaging bag of this embodiment may be for boiling or retorting. Examples of the packaging bag include a flat pouch-shaped packaging bag and a self-standing packaging bag (standing pouch).

[0122] The flat pouch-shaped packaging bag may be, for example, a bag-shaped bag made by folding one sheet of packaging material (packaging material including a sealant layer) in half so that the sealant layers face each other, and then heat-sealing three sides, or may be a bag-shaped bag made by stacking two sheets of packaging material (packaging material including a sealant layer) on top of each other so that the sealant layers face each other, and then heat-sealing four sides.

[0123] The self-standing packaging bag may be, for example, a bag-shaped bag made by stacking three sheets of packaging material (packaging material including a sealant layer) with the sealant layers of the two sheets facing each other, and then inserting one sheet of packaging material (packaging material including a sealant layer) between the two sheets, folded in half with the sealant layer facing outward, and then heat-sealing the four sides.

[0124] In the packaging bag of this embodiment, the amount of chloride ion migration measured and calculated under the following conditions can be less than 1 μg / mL. Conditions for measuring and calculating the amount of chloride ion migration: A package containing 200 mL of water in a packaging bag is prepared, and the package is heat-treated at 121°C for 30 minutes. The water is removed from the package after the heat treatment, and the chloride ion content of the water is measured using an ion chromatogram, and the amount of chloride ion migration is calculated using the following formula: Amount of chloride ion migration (unit: μg / mL) = Chloride ion content of water after heat treatment (unit: μg / mL) - Chloride ion content of water before being placed in the package (unit: μg / mL).

[0125] The above-mentioned package may be obtained by placing 200 mL of water in the packaging bag of this embodiment and heat-sealing the opening of the packaging bag. In this case, the seal width may be, for example, 3 to 20 mm. If the packaging bag does not have an opening, an opening may be provided, water may be placed inside, and the opening may then be heat-sealed.

[0126] From the viewpoint of further reducing the effect of the packaging on the odor of the contents, the amount of chloride ion migration measured and calculated under the above conditions may be 0.5 μg / mL or less, 0.3 μg / mL or less, or 0 μg / mL.

[0127] <Packaging> Another embodiment of the present disclosure is a packaging including the packaging bag of the above embodiment and contents accommodated in the packaging bag. The contents may include liquids such as liquid seasonings, toiletries, soups, and liquid detergents, solids such as simmered dishes, and solid-liquid mixtures of liquids and solids such as curry.

[0128] The present disclosure will be described in more detail with reference to the following examples and comparative examples, but the present disclosure is not limited to these examples.

[0129] <Preparation of Sealant Film> 92.0 parts by mass of a propylene-ethylene block copolymer, 8.0 parts by mass of an ethylene-α-olefin copolymer, and 5 parts by mass of titanium oxide as a white pigment were premixed by dry blending. The resulting premix was kneaded at 200 to 230°C using a continuous kneading extruder and pelletized. The resulting pellets were then charged into an extruder, heated to 220°C, and extruded using an inflation device to produce a sealant film by inflation molding. The sealant film had a thickness of 60 μm. The lightness L* value of the resulting sealant film was 89. In this example, the lightness L* value was measured using an X-rite 528 manufactured by X-rite Corporation.

[0130] A sealant film having a lightness L* value of 80 (4 parts by mass of titanium oxide mixed with 100 parts by mass of the resin component), a sealant film having a lightness L* value of 75 (3.7 parts by mass of titanium oxide mixed with 100 parts by mass of the resin component), and a sealant film having a lightness L* value of 73 (3.5 parts by mass of titanium oxide mixed with 100 parts by mass of the resin component) were produced in the same manner as above, except that the blending ratios of the propylene-ethylene block copolymer and ethylene-α-olefin copolymer (resin components) to titanium oxide were adjusted.

[0131] Example 1 A printed layer was formed on one surface of a gas barrier film (transparent vapor-deposited barrier film "GL-ARH", manufactured by TOPPAN Corporation, thickness 12 μm) by gravure printing oil-based colored inks (red ink, yellow ink, indigo ink, black ink), to obtain a printed gas barrier film. The colored inks used were "Rio Alpha Red", "Rio Alpha Yellow", "Rio Alpha Indigo" and "Rio Alpha Black" manufactured by Toyo Ink Co., Ltd. In all colored inks, the ratio of the pigment content to the binder resin content (pigment / resin ratio) was 1.6 or less by mass. A test chart with a gradation pattern was used as the design.

[0132] Next, a substrate film (ONY film, "ONMB-RT", manufactured by Unitika Ltd., thickness 15 μm) was laminated so as to face the printed layer of the printed gas barrier film, and further, a sealant film with a lightness L* value of 89 was laminated so as to face the substrate film. In the lamination process, a solvent-free adhesive was used, which was a mixture of "TSN-4864A" (manufactured by Toyo-Morton Co., Ltd.) and "TSN-4864B3" (manufactured by Toyo-Morton Co., Ltd.) in a mass ratio of 100:100. The solvent-free adhesive was applied at an adhesive temperature of 80°C (viscosity of approximately 600 mPa s) with a coating amount of 2 g / m ２ The coating was performed using a roll coater so that the adhesive was cured by aging for 72 hours in an environment of 40°C, thereby obtaining a laminate having a laminate structure of [layer made of gas barrier film (gas barrier film layer) / printed layer / solventless adhesive layer / layer made of base film (base film layer) / solventless adhesive layer / layer made of sealant film (sealant layer)]. The lightness L* value of the laminate measured from the sealant layer side was 87.

[0133] Example 2 A laminate was obtained in the same manner as in Example 1, except that a printed layer was formed by flexographic printing with water-based colored inks (red ink, yellow ink, indigo ink, and black ink). The colored inks used were "Aquariona Crimson" (red ink), "Aquariona Yellow" (yellow ink), "Aquariona Indigo" (indigo ink), and "Aquariona Black" (black ink), all manufactured by Toyo Ink Co., Ltd. In all colored inks, the ratio of the pigment content to the binder resin content (pigment / resin ratio) was 1.6 or less by mass. The lightness L* value of the laminate measured from the sealant layer side was 87.

[0134] Example 3 A laminate was obtained in the same manner as in Example 1, except that a sealant film having a lightness L* value of 80 was used. The lightness L* value of the laminate measured from the sealant layer side was 79.

[0135] Example 4 A laminate was obtained in the same manner as in Example 2, except that a sealant film having a lightness L* value of 80 was used. The lightness L* value of the laminate measured from the sealant layer side was 79.

[0136] Example 5 A laminate was obtained in the same manner as in Example 1, except that a sealant film having a lightness L* value of 75 was used. The lightness L* value of the laminate measured from the sealant layer side was 75.

[0137] Comparative Example 1 A printed gas barrier film was prepared in the same manner as in Example 1. Next, a white ink layer was formed by gravure printing oil-based white ink twice on the printed layer of the printed gas barrier film so that it overlapped the printed layer. "Lio Alpha White" manufactured by Toyo Ink Co., Ltd. was used as the white ink. The lightness L* value of the white ink layer was 79. Next, a base film (ONY film, "ONMB-RT", manufactured by Unitika Ltd., thickness 15 μm) was laminated facing the white ink layer, and a PP sealant film "ZK207" (manufactured by Toray Advanced Film Co., Ltd., thickness 60 μm) with a lightness L* value of 18 was further laminated facing the base film. The lamination was performed in the same manner as in Example 1. The solvent-free adhesive was then cured by aging for 72 hours in an environment of 40°C, yielding a laminate having a laminate structure of [layer made of gas barrier film (gas barrier film layer) / printed layer / white ink layer / solvent-free adhesive layer / layer made of base film (base film layer) / solvent-free adhesive layer / layer made of sealant film (sealant layer)]. The lightness L* value of the laminate measured from the sealant layer side was 80.

[0138] Comparative Example 2 A laminate was obtained in the same manner as in Comparative Example 1, except that a printed layer was formed by flexographic printing the same water-based colored inks (red ink, yellow ink, indigo ink, and black ink) as in Example 2, and a white ink layer was formed by flexographic printing an water-based white ink. "Aquariona White" manufactured by Toyo Ink Co., Ltd. was used as the white ink. The lightness L* value of the white ink layer was 70, and the lightness L* value of the laminate measured from the sealant layer side was 71.

[0139] Comparative Example 3 A laminate was obtained in the same manner as in Comparative Example 2, except that flexographic printing was performed twice so as to overlap the white ink when forming the white ink layer. The lightness L* value of the white ink layer was 75, and the lightness L* value of the laminate measured from the sealant layer side was 76.

[0140] Comparative Example 4 A laminate was obtained in the same manner as in Comparative Example 2, except that flexographic printing was performed three times so as to overlap the white ink when forming the white ink layer. The lightness L* value of the white ink layer was 79, and the lightness L* value of the laminate measured from the sealant layer side was 80.

[0141] <Evaluation> The laminates obtained in Examples 1 to 5 and Comparative Examples 1 to 4 were evaluated according to the following evaluation items. The results are shown in Table 1.

[0142] (Appearance) Visual observation of 1 m in the flow direction was performed and evaluated according to the following evaluation criteria. Evaluation criteria: A: No bubbles with a diameter of 0.5 mm or more are present. B: Bubbles with a diameter of 0.5 mm or more but less than 1 mm are present, but no bubbles with a diameter of 1 mm or more are present. C: Bubbles with a diameter of 1 mm or more are present.

[0143] (Saturation) The saturation of the 100% density areas of yellow (Y), magenta (M), and cyan (C) was measured. The higher the saturation, the more vivid the image is evaluated to be. Saturation was measured by the following method. The laminate was placed on a blackboard with the sealant layer side facing downwards, and L*a*b* was measured from the gas barrier film layer side. Saturation was calculated from the measured values ​​of a* and b*. A reflection spectrocolor densitometer (X-Rite 528, manufactured by X-Rite Corporation) was used to measure L*a*b*.

[0144] (Hiding Property) The laminate was placed on a white board and a black board with the sealant layer side facing downwards, and the L*a*b* on the white board and the L*a*b* on the black board were measured from the gas barrier film layer side. The color difference ΔE* between them was calculated using the following formula, and the hiding property was evaluated according to the following evaluation criteria. The measurement location was the white part (the part where colors such as yellow, magenta, cyan, etc. were not present). The smaller the ΔE*, the less the influence of the base, and the better the hiding property. If the evaluation is A (ΔE* is less than 15), the laminate has sufficient hiding property. Evaluation criteria: A: ΔE is less than 15. B: ΔE* is 15 or more but less than 20. C: ΔE* is 20 or more.

[0145] (Light-shielding property) Using a turbidity meter (NDH-2000, manufactured by Nippon Denshoku Industries Co., Ltd.), the total light transmittance was measured in accordance with JIS-K7361-1. The light-shielding property was evaluated according to the following evaluation criteria. If the evaluation is A (total light transmittance less than 45%), the laminate has sufficient light-shielding property. Evaluation criteria: A: Total light transmittance less than 45%. B: Total light transmittance 45% or more but less than 60%. C: Total light transmittance 60% or more.

[0146] (Odor) Two laminates obtained in each example were stacked with the sealant layers facing each other, and then heat-sealed on three sides using a heat sealer manufactured by Tester Sangyo Co., Ltd. under conditions of a sealing pressure of 0.2 MPa, a sealing time of 1 second, a sealing width of 10 mm, and a sealing temperature of 150°C to produce a packaging bag (150 mm long x 210 mm wide) with an opening. Mineral water (200 mL) was placed into the produced packaging bag through the opening, and the opening was heat-sealed under the same conditions to produce a package. The produced package was subjected to a heat treatment (retort treatment) at 121°C for 30 minutes, after which the package was opened and the odor (off-odor) inside the package was evaluated by three panelists according to the following criteria. The odor (off-odor) included both a solvent odor and a chlorine odor, and if at least one of the solvent odor and the chlorine odor was detected, it was evaluated as having an odor. Evaluation criteria: A: No odor or a weak odor is detected, but no practical problem. B: A moderate odor is detected, but no practical problem. C: A strong odor is detected, and there is a practical problem.

[0147] In Examples 1, 3 and 5, all three panelists perceived the solvent odor stronger than the chlorine odor.

[0148] (Amount of chloride ions transferred) A package filled with mineral water was prepared and the package was retorted under the same conditions as those for the odor evaluation. Next, the package after the retort treatment was opened, and the mineral water was removed. The chloride ion content of the removed mineral water was measured using an ion chromatogram, and the amount of chloride ions (Cl) transferred to the mineral water was calculated using the following formula: －The amount of chloride ion migration (unit: μg / mL) was calculated and evaluated according to the following criteria: Amount of chloride ion migration (unit: μg / mL) = Chloride ion content in mineral water after retort treatment (unit: μg / mL) - Chloride ion content in mineral water before filling into packaging bags (unit: μg / mL) Evaluation criteria: A: The amount of chloride ion migration is 0 μg / mL or less B: The amount of chloride ion migration is more than 0 μg / mL and less than 1 μg / mL C: The amount of chloride ion migration is 1 μg / mL or more

[0149]

[0150] 10, 20...Laminate, 1...Gas barrier film layer, 2...Printed layer, 3...Sealant layer, 4...Base film layer, S1...First adhesive layer, S2...Second adhesive layer.

Claims

1. A laminate comprising a gas barrier film layer, an adhesive layer, and a sealant layer in this order, wherein the adhesive layer is a layer formed from a solventless adhesive, and the sealant layer is a layer made from a composition containing a polyolefin resin and a white pigment.

2. The laminate according to claim 1, further comprising a printed layer formed from at least one type of ink, including a color ink other than white ink, between the gas barrier film layer and the adhesive layer.

3. The laminate according to claim 2, wherein the printed layer is a layer formed from a water-based ink.

4. The laminate according to any one of claims 1 to 3, wherein the solvent-free adhesive is a two-component curing polyurethane adhesive.

5. The laminate according to any one of claims 1 to 4, wherein the polyolefin resin is a polypropylene resin.

6. The laminate according to any one of claims 1 to 5, wherein the lightness L* value of the sealant layer based on the color system specified in JIS Z8781-4 is 75 or more.

7. A packaging material comprising the laminate according to any one of claims 1 to 6.

8. A packaging bag made from the packaging material according to claim 7.

9. The packaging bag according to claim 8, which is for boiling or retorting.

10. The packaging bag according to claim 8 or 9, wherein the amount of chloride ion migration measured and calculated under the following conditions is less than 1 μg / mL. Conditions for measuring and calculating the amount of chloride ion migration: A package containing 200 mL of water is prepared in the packaging bag, and the package is heat-treated at 121°C for 30 minutes. The water is removed from the package after the heat treatment, and the chloride ion content of the water is measured using an ion chromatogram, and the amount of chloride ion migration is calculated using the following formula: Amount of chloride ion migration (unit: μg / mL) = Chloride ion content of water after heat treatment (unit: μg / mL) - Chloride ion content of water before being placed in the packaging bag (unit: μg / mL).

11. A package comprising the packaging bag according to any one of claims 8 to 10 and contents contained in the packaging bag.

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