Laminates, packaging materials, packaging bags and packaging bodies

Abstract

To provide a laminate that excels at suppressing the deterioration of the quality of its contents. [Solution] A laminate comprising, in this order, a first substrate layer having a printing layer, a first adhesive layer, a second substrate layer having a gas barrier layer, a second adhesive layer, and a sealant layer, wherein the printing layer is a layer formed from water-based ink.

Description

[Technical Field]

[0001] This disclosure relates to laminates, packaging materials, packaging bags, and packaging bodies. [Background technology]

[0002] As part of environmental initiatives, packaging bags made of plastic (e.g., flexible packaging bags) are becoming widespread. The packaging materials used in these bags require various functions depending on their application, such as strength, light shielding, concealment, water resistance, moisture resistance, gas barrier properties, and heat resistance. To improve these functions, typical packaging materials consist of laminates made up of multiple layers with various functional properties.

[0003] As an example of such a laminate, one is known to comprise, in this order, a gas barrier film layer, an aqueous ink layer formed on the gas barrier film layer, an intermediate substrate layer, and a thermoplastic resin layer (sealant layer) (see Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-066031 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Packaging bags for food, cosmetics, pharmaceuticals, etc., can be manufactured from the above-mentioned laminated material. The packaging bag is required to have as little impact as possible on the quality of the contents, regardless of the type of contents or post-packaging processing. However, from this perspective, there is room for improvement in the conventional laminates that constitute packaging bags.

[0006] This disclosure is made in view of the above circumstances and aims to provide a laminate that is excellent at suppressing deterioration of the quality of its contents. This disclosure also aims to provide packaging materials, packaging bags, and packaging bodies using the laminate. [Means for solving the problem]

[0007] The inventors noticed that when food is placed in conventional laminated packaging bags, especially when the resulting packaging is heat-sterilized, a small amount of odor may adhere to the contents. This deterioration in quality due to odor adhesion can be a problem not only for humans but also for pets such as dogs and cats, which have a sensitive sense of smell. The inventors conducted a thorough analysis of each constituent layer of the laminate and found that a small amount of chlorine originating from the water-based ink layer of the laminate may transfer to the contents. Therefore, in order to address this odor (chlorine odor) problem, they considered it preferable to give the intermediate substrate layer (second substrate layer) barrier properties, and thus formed the laminate of this disclosure.

[0008] Some aspects of this disclosure are, for example, the following: [1] comprising, in this order, a first substrate layer having a printing layer, a first adhesive layer, a second substrate layer having a gas barrier layer, a second adhesive layer, and a sealant layer, A laminate in which the aforementioned printing layer is a layer formed from water-based ink. [2] The laminate according to [1], wherein the first substrate layer has the printing layer on the side facing the first adhesive layer. [3] The laminate according to [1] or [2], wherein the gas barrier layer comprises an inorganic oxide vapor deposition layer or a metal vapor deposition layer. [4] The laminate according to any one of [1] to [3], wherein the sealant layer contains a white pigment. [5] The laminate according to any one of [1] to [4], wherein the first adhesive layer and the second adhesive layer are layers formed from a solvent-free adhesive. [6] A packaging material comprising a laminate described in any one of [1] to [5]. [7] A packaging bag made by forming a bag from the packaging material described in [6]. [8] Packaging bags as described in [7], for boiling or retorting. A package comprising a packaging bag as described in [9] [7] or [8], and contents contained in the packaging bag. [Effects of the Invention]

[0009] According to this disclosure, it is possible to provide a laminate that is excellent at suppressing deterioration of the quality of its contents. Specifically, according to this disclosure, even if the laminate includes an aqueous ink layer, it is possible to provide a laminate that is excellent at suppressing odor adhesion to its contents. According to this disclosure, packaging materials, packaging bags, and packaging bodies using the laminate can be provided. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic cross-sectional view showing one embodiment of the laminate of the present disclosure. [Modes for carrying out the invention]

[0011] In this disclosure, numerical ranges indicated using "~" represent a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. Unless otherwise explicitly stated, the units of the numbers before and after "~" are the same. In numerical ranges described in stages within this disclosure, the upper or lower limit of one stage may be replaced by the upper or lower limit of another stage. Furthermore, in numerical ranges described within this disclosure, the upper or lower limit of that range may be replaced by the values ​​shown in the examples. Also, individually described upper and lower limits can be combined in any way. Additionally, "A or B" may include either A or B, or both.

[0012] The embodiments of this disclosure will be described in detail below, with reference to the drawings as appropriate. However, this disclosure is not limited to the embodiments described below. The laminates described below can be used, for example, as packaging materials for forming packaging bags, but the applications of the laminates are not limited to this.

[0013] <Laminated body> FIG. 1 is a schematic cross-sectional view showing an embodiment of the laminated body of the present disclosure. The laminated body 10 in FIG. 1 includes a first base material layer 1, a printing layer 2, a first adhesive layer S1, a gas barrier layer 3, a second base material layer 4, a second adhesive layer S2, and a sealant layer 5 in this order. The printing layer 2 is a layer formed from aqueous ink. The thickness of the laminated body 10 is, for example, 40 to 150 μm.

[0014] The laminated body 10 can be obtained, for example, by laminating a printed base material film obtained by forming a printing layer 2 on a first base material layer 1, a gas barrier film obtained by forming a gas barrier layer 3 on a second base material layer 4, and a sealant film constituting a sealant layer 5 via a first adhesive layer S1 and a second adhesive layer S2.

[0015] Hereinafter, each layer constituting the laminated body 10 will be described.

[0016] [First base material layer] The first base material layer 1 may be a known resin film used for a packaging bag on which the printing layer 2 can be formed. The first base material layer 1 is, for example, a stretched film such as a biaxially stretched resin film. Examples of the resin constituting 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 first base material layer 1, a composite film in which two or more resin films are laminated can also be used.

[0017] The first substrate layer 1 may be transparent so that the pattern created by the printing layer 2 can be displayed regardless of which surface the printing layer 2 is applied to. Here, transparency of the first substrate layer 1 means that the total light transmittance of the film, measured in accordance with JIS K7361-1:1997 using a color and turbidity simultaneous measuring instrument (COH400, manufactured by Nippon Denshoku Industries Co., Ltd.), is 85% or more.

[0018] The thickness of the first substrate layer 1 is, for example, 4 to 60 μm.

[0019] [Print layer] Printed layer 2 is a layer formed by printing ink. Here, ink containing pigment and binder resin is called colored ink, and colored ink containing only white pigment as the pigment is specifically called white ink. Printed layer 2 contains at least pigment and binder resin. Note that the composition of ink used as a material for printing and the ink contained in the printed layer may differ due to the influence of layer formation processes such as drying and curing, but in this disclosure, for convenience, these are collectively referred to as ink.

[0020] As the colored ink, known colored inks (for example, red ink, yellow ink, cyan ink, black ink, white ink) can be used.

[0021] The type of pigment contained in colored inks other than white ink may be determined as appropriate depending on the color to be expressed. For example, inorganic pigments or organic pigments may be used as 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 underglaze lake pigments. Multiple types of pigments may be used in combination.

[0022] Examples of materials that make up the pigments contained in white inks include inorganic oxides such as titanium dioxide, alumina, mica, lead oxide (lead white), 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 dioxide are preferred in terms of opacity and dispersibility when added. The titanium dioxide may be of the rutile or anatase type. The surface of the pigment containing titanium dioxide may be treated with a metal oxide such as aluminum (Al) or silicon (Si). The average particle size of the white pigment can be selected within a range that does not hinder the purpose of this disclosure.

[0023] Examples of binder resins 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, and ethylcellulose. These can be used individually or in combination of two or more.

[0024] The ratio of pigment content to binder resin content (pigment / resin ratio) is, for example, 1.6 or less by mass ratio, preferably 0.5 to 1.6. A mass ratio (pigment / resin ratio) of 1.6 or less makes it easier to obtain a better appearance.

[0025] The ink forming the printing layer 2 may consist only of white ink, only of colored inks other than white ink, or of colored inks other than white ink and colorless ink (ink without pigment). The ink forming the printing layer 2 may also contain a white ink with a smaller amount of pigment compared to a white ink used to improve light shielding and opacity (for example, a white ink in which the ratio of pigment content to binder resin content (pigment / resin ratio) is 0.5 to 1.6 by mass). From the viewpoint of reducing the number of microscopic cavities caused by gaps between pigments formed within the printed layer and obtaining a better appearance, the ink does not necessarily need to contain white ink.

[0026] The ink forming the printed layer 2 is an aqueous ink from an environmental protection standpoint. A water-based binder resin may be used for the aqueous ink. Examples of aqueous binder resins include emulsion-type binder resins, colloidal dispersion-type binder resins, and water-soluble binder resins. Examples of aqueous binder resins include acrylic resins, polyester resins, urethane acrylic resins, styrene acrylic resins, styrene maleic acid resins, as well as water-soluble polyamide resins, aqueous polyester resins, and aqueous polyurethane resins.

[0027] If the ink is water-based, water or an aqueous solvent containing water and an organic solvent (diluting water) can be used as the solvent. Examples of water include tap water, distilled water, and deionized water. Examples of organic solvents include lower alcohols, polyhydric alcohols and their alkyl ethers or alkyl esters. Specific examples of organic solvents include lower alcohols such as methanol, ethanol, n-propanol, and isopropanol; polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, and glycerin; and 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.

[0028] The chlorine concentration in the aqueous solvent is preferably low from the viewpoint of suppressing the transfer of chlorine (odor) to the contents, for example, preferably 1 mg / L, and more preferably 0.1 mg / L. The chlorine concentration is preferably substantially 0 mg / L, but may be greater than 0 mg / L.

[0029] The ink may contain, as necessary, one or more additives such as plasticizers, stabilizers, antioxidants, light stabilizers, UV absorbers, curing agents, crosslinking agents, lubricants, antistatic agents, and fillers.

[0030] The printing layer 2 may be a layer that displays images such as characters, figures, symbols, and patterns. There are no particular restrictions on the types of images that can be expressed by the printing layer, and the type of ink used may be appropriately determined accordingly. Such a printing layer 2 may have only an image, or it may have an image in addition to a white ink layer. A printing layer 2 that does not have a white ink layer can be said to be a printing layer formed from at least one type of ink that includes a color ink other than white ink.

[0031] The thickness of the printed layer 2 is, for example, 0.2 to 8 μm.

[0032] The printed layer 2 can be formed by printing methods such as gravure printing, letterpress printing, screen printing, transfer printing, and flexographic printing.

[0033] The printed layer 2 is generally provided on the side of the first substrate layer 1 that faces the contents, but it may also be provided on the side opposite to the contents. Even if the printed layer 2 is provided on the side of the first substrate layer 1 that faces the contents, the above-described laminate can suppress the migration of chlorine to the contents.

[0034] [Second base layer] The second base layer 4 may be a known resin film used for packaging bags, on which a gas barrier layer 3 can be formed. The second base layer 4 is, for example, a stretched film such as a biaxially oriented resin film. Examples of resins constituting 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 made by laminating two or more films can be used.

[0035] The thickness of the second substrate layer 4 is, for example, 4 to 60 μm.

[0036] [Gas barrier layer 3] The gas barrier layer 3 is a layer that has barrier properties against at least one gas, such as oxygen gas or water vapor. The gas barrier layer may be a layer that has oxygen barrier properties, or it may be a layer that has water vapor barrier properties. Here, the statement that a layer has oxygen barrier properties means that, in accordance with JIS K7126-2 (2006), the oxygen permeability (OTR, unit: cc / m³) measured using an oxygen permeability measuring device (MOCON OX-TRAN2 / 21 model) under conditions of 25°C and 80% relative humidity. 2 ( / day / atm) is 2cc / m 2 This means it is less than or equal to / day / atm. Furthermore, the layer possesses water vapor barrier properties, as determined by the water vapor transmission rate (WVTR, unit: g / m³) measured under conditions of 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 1.0g / m² 2 This means it is less than or equal to / day.

[0037] The gas barrier layer 3 may have not only gas barrier properties against oxygen gas and water vapor, but also aroma-retaining properties for the contents.

[0038] The gas barrier layer 3 also has the function of suppressing the migration of trace amounts of chlorine, which originates from the water-based ink layer (printing layer 2), to the contents.

[0039] From the viewpoint of resistance to the contents of the adhesive, the gas barrier layer 3 may be provided on the side of the second base material layer 4 that faces the contents. On the other hand, if the gas barrier layer 3 itself is susceptible to the effects of the contents, the gas barrier layer 3 may be provided on the side of the second base material layer 4 that is opposite to the side facing the contents.

[0040] The gas barrier layer 3 includes a vapor-deposited layer (an inorganic oxide vapor-deposited layer or a metal vapor-deposited layer).

[0041] An inorganic oxide vapor-deposited layer is a layer formed by vapor-depositing an inorganic material such as a metal oxide. Examples of metal oxides include silicon oxide and aluminum oxide. Aluminum oxide is preferred as the metal oxide. A metal vapor-deposited layer is a layer formed by depositing a metal material. Aluminum is an example of such a metal material. Methods for forming the vapor-deposited layer include, for example, physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating, and chemical vapor deposition (CVD) methods such as plasma chemical vapor deposition, thermochemical vapor deposition, and photochemical vapor deposition.

[0042] When the inorganic oxide vapor deposition layer is a silicon oxide or aluminum oxide (alumina) vapor deposition layer, the thickness of the vapor deposition layer is preferably 1 to 100 nm, more preferably 10 to 50 nm, and even more preferably 20 to 30 nm. When the metal vapor deposition layer is an aluminum vapor deposition layer, the thickness of the vapor deposition layer is preferably 10 to 100 nm.

[0043] The second substrate layer 4, on which the gas barrier layer 3 is provided, can be called a gas barrier film. The gas barrier film may include a primer layer between the gas barrier layer 3 and the second substrate layer 4. The gas barrier film may also have a laminated structure in which the second substrate layer 4, the primer layer, and the vapor-deposited layer are laminated in that order. The primer layer may contain either a trialkoxysilane or a hydrolysis product of a trialkoxysilane, an acrylic polyol, and an isocyanate compound as a reaction product.

[0044] Trialkoxysilanes have the general formula R 1 Si(OR 2 ) is shown by 3. 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. R 1 The alkyl group contained in 1 may be a linear alkyl group, a branched alkyl group, or a cyclic alkyl group. R 1 can be appropriately changed according to the second base material layer 4 and the material constituting the gas barrier layer. OR 2 is a hydrolyzable alkoxy group such as a methoxy group, an ethoxy group, or an ethoxymethoxy group. The hydrolysis product of trialkoxysilane can be obtained, for example, by adding an acid or an alkali to trialkoxysilane to hydrolyze the trialkoxysilane.

[0045] Specific examples of trialkoxysilane include ethyltrimethoxysilane, vinyltrimethoxysilane, isocyanate propyltriethoxysilane, γ-isocyanate propyltrimethoxysilane, glycidoxypropyltrimethoxysilane, and epoxycyclohexyl ethyltrimethoxysilane. Among these, isocyanate propyltriethoxysilane and γ-isocyanate propyltrimethoxysilane containing an isocyanate group are preferred. Also, glycidoxypropyltrimethoxysilane having a glycidoxy group and epoxycyclohexyl ethyltrimethoxysilane containing an epoxy group are preferred. Trialkoxysilane is, for example, one or a combination of two or more selected from the above-described compounds.

[0046] Acrylic polyols are, for example, homopolymers of acrylic acid derivative monomers, or copolymers of acrylic acid derivative monomers with styrene, etc. Copolymers of acrylic acid derivative monomers may contain compounds having hydroxyl groups at their terminals and reacted with the isocyanate group of an isocyanate compound. Examples of acrylic acid derivative monomers are ethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, or hydroxybutyl methacrylate. Acrylic polyols are, for example, one or more combinations selected from the above-mentioned compounds.

[0047] Isocyanate compounds are, for example, aromatic isocyanate compounds or aliphatic isocyanate compounds. Furthermore, isocyanate compounds are polymers of aromatic isocyanate compounds or aliphatic isocyanate compounds with polyols. Also, isocyanate compounds are derivatives produced from polymers of aromatic isocyanate compounds, aliphatic isocyanate compounds, and polyols. Isocyanate compounds are, for example, one or more compounds selected from the above-mentioned compounds.

[0048] Commercially available gas barrier films may be used. Examples of commercially available products include the "GL BARRIER" series from TOPPAN Corporation, the "Barrierox" series from Toray Film Processing Co., Ltd., the "Max Barrier" series from Mitsui Chemicals Tohcello, and the "Tech Barrier" series from Mitsubishi Chemical Corporation.

[0049] The thickness of the gas barrier film is, for example, 4 to 60 μm.

[0050] [Adhesive layer] Adhesive layers S1 and S2 are layers formed from a solvent-based adhesive or a solvent-free adhesive (solvent-based adhesive layer or solvent-free adhesive layer, respectively). Adhesive layers S1 and S2 may be layers formed from the same adhesive or layers formed from different adhesives.

[0051] A solvent-based adhesive layer refers to an adhesive that contains a solvent (organic solvent and water) (solvent content exceeding 0.5% by mass). For solvent-based adhesives, polyester polyols, polyether polyols, or mixtures thereof, with a weight-average molecular weight of 5000 or more can be used. Solvent-free adhesives are adhesives that substantially contain no solvents (organic solvents and water) (solvent content is 0.5% by mass or less). Because solvent-free adhesives substantially contain no solvents, they have a low environmental impact on the manufacturing process and reduce the risk of solvent odors transferring to the contents. Furthermore, solvent-free adhesives have the advantage of being able to be applied more thinly than solvent-based adhesives. Solvent-free adhesives can use polyester polyols, polyether polyols, or mixtures thereof, with a weight-average molecular weight of less than 5000.

[0052] Whether an adhesive layer is a solvent-based adhesive layer or a solvent-free adhesive layer can be confirmed, for example, by analysis using Fourier transform infrared spectroscopy.

[0053] For solvent-based adhesives, the same adhesives as those described later for solvent-free adhesives can be used, except that a solvent is used.

[0054] Examples of solvent-free adhesives include polyurethane adhesives. Polyurethane adhesives may be one-component or two-component curing types, but two-component curing types are preferred. When the solvent-free adhesive is a two-component curing polyurethane adhesive, the appearance tends to be superior.

[0055] A two-component curing polyurethane adhesive comprises a main component and a curing agent. Examples of the main component include polyester polyols, polyether polyols, acrylic polyols, polyether ester polyols, and polyurethane polyols. Examples of the curing agent include bifunctional or multifunctional polyisocyanate compounds. The polyisocyanate compound may be an aliphatic polyisocyanate, an aromatic polyisocyanate, or a mixture thereof.

[0056] Polyester polyols are, for example, esterification products of polycarboxylic acids, dialkyl esters of polycarboxylic acids, or mixtures thereof, with glycol-based compounds. Examples of polycarboxylic acids include succinic acid, glutaric acid, isophthalic acid, terephthalic acid, adipic acid, pimelic acid, corticic acid, azelaic acid, sebatic acid, dodecanedioic acid, and dimer acids. 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.

[0057] 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.

[0058] Polyether ester polyols are, for example, esterification products of polycarboxylic acids, dialkyl esters of polycarboxylic acids, or mixtures thereof, with polyether polyols.

[0059] Polyurethane polyols are reaction products of, for example, polyester polyols, polyether polyols, polyether ester polyols, or mixtures thereof, with polyisocyanate monomers.

[0060] Aliphatic polyisocyanates and aromatic polyisocyanates may be polyisocyanate monomers, polyisocyanate derivatives, or polyisocyanate-terminated prepolymers.

[0061] Examples of aliphatic polyisocyanates include polyisocyanate monomers such as tetramethylene diisocyanate, isopropyl diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate, 1,3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, lysine diisocyanate, and isophorone diisocyanate.

[0062] Examples of aromatic polyisocyanates include tolylene diisocyanate, phenylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, and tetramethylxylylene diisocyanate.

[0063] Polyisocyanate derivatives are, for example, isocyanurates derived from polyisocyanate monomers.

[0064] The polyisocyanate-terminated prepolymer may be a difunctional polyisocyanate containing terminal isocyanate groups obtained by reacting a polyisocyanate monomer with a difunctional polyol compound such as polypropylene glycol, or it may be a polyfunctional polyisocyanate containing terminal isocyanate groups obtained by reacting a polyisocyanate monomer with a trifunctional or higher polyol compound such as trimethylolpropane.

[0065] Solvent-based adhesives and solvent-free adhesives harden into an adhesive layer by reacting, for example, through heating (for example, the hydroxyl groups of the main component react with the isocyanate groups of the curing agent). When using solvent-based adhesives, specifically, the adhesive is applied to one film, the solvent is dried by passing it through a dryer at 50-200°C, the other film is then placed on top to create a laminate, and the adhesive is further aged at 30-120°C for several hours to several days, causing it to harden and form an adhesive layer between the two films. When using a solvent-free adhesive, specifically, the adhesive is heated to 40-120°C to achieve a suitable viscosity for coating, applied to one film, and then irradiated with heat, ultraviolet light, electron beams, or infrared light as needed. The other film is then placed on top to create a laminate, and the film is further aged at 30-120°C for several hours to several days, at which point the adhesive hardens and forms an adhesive layer between the two films. The adhesive layer formed in this manner includes a cured product of a solvent-based adhesive or a solvent-free adhesive. The application amount of each adhesive is, for example, 0.5 to 5.0 g / m². 2 That is the case.

[0066] The thicknesses of the adhesive layers S1 and S2 may be the same or different, for example, 0.3 to 5.0 μm.

[0067] [Sealant layer] The sealant layer 5 comprises a polyolefin resin, or a composition containing a polyolefin resin and a white pigment (a milky white polyolefin resin composition). The sealant layer 5 is a layer for heat sealing when forming the laminate 10 into a packaging bag, and has heat-adhesive properties.

[0068] Examples of polyolefin resins include ethylene resins, polypropylene resins, propylene resins, ethylene-propylene copolymers, ethylene-α,β unsaturated carboxylic acid copolymers, esterified products of ethylene-α,β unsaturated carboxylic acid copolymers, acid anhydride-modified polyolefins, and blends of two or more of these. Among these, polypropylene resins (especially CPP: unstretched polypropylene resins) are particularly preferred because they have excellent thermal adhesion, as well as heat resistance and oil resistance.

[0069] Ethylene-based resins include, for example, low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), linear low-density polyethylene (L·LDPE), or ethylene-α-olefin copolymers.

[0070] Polypropylene resins include, for example, homopolypropylene, block polypropylene, or random polypropylene.

[0071] Propylene-based resins are, for example, propylene-α-olefin copolymers.

[0072] Ethylene-α,β unsaturated carboxylic acid copolymers are, for example, ethylene-acrylic acid copolymers or ethylene-methacrylic acid copolymers.

[0073] Acid anhydride-modified polyolefins are, for example, terpolymers such as ethylene-maleic anhydride graft copolymers and ethylene-ethyl acrylate-maleic anhydride copolymers.

[0074] Examples of materials constituting white pigments include inorganic oxides such as titanium dioxide, alumina, mica, lead oxide (lead white), 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 dioxide are preferred in terms of opacity and dispersibility when added. The titanium dioxide may be of the rutile or anatase form. The surface of the pigment containing titanium dioxide 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 hinder the purpose of this disclosure.

[0075] If the sealant layer 5 contains a white pigment, the polyolefin resin content 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 5 (total mass of the milky white polyolefin resin composition), from the viewpoint of thermal adhesion. The polyolefin resin content 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 the viewpoint of light shielding and opacity. From these viewpoints, the polyolefin resin content may be 90 to 97% by mass, based on the total mass of the sealant layer.

[0076] If the sealant layer 5 contains a white pigment, 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 5 (total mass of the milky white polyolefin resin composition), from the viewpoint of light shielding and opacity. From the viewpoint of thermal adhesion, the content of the white pigment may be 10% 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, based on the total mass of the sealant layer.

[0077] The ratio of the white pigment content to the polyolefin resin content (pigment / resin ratio) may be 0.04 to 0.1 by mass, and may also be 0.04 to 0.08 or 0.05 to 0.06.

[0078] The sealant layer 5 may contain other additives as needed. Examples of other additives include antioxidants, slip agents, antiblocking agents, and weather-resistant agents.

[0079] The sealant layer 5 may be a single layer or a multilayer structure. When the sealant layer 5 contains a white pigment, and the sealant layer 5 is a multilayer structure, all constituent layers are layers containing polyolefin resin, and for example, at least one of these layers may be a layer containing a milky white polyolefin resin composition. In that case, it is preferable that the layer containing the milky white polyolefin resin composition is located on the first substrate layer 1 side (printing layer 2 side). Also, for example, when the sealant layer 5 has a three-layer structure consisting of an outer layer / intermediate layer / outer layer, it is preferable that the intermediate layer is a layer containing a milky white polyolefin resin composition. The polyolefin resins used in each layer may be the same or different.

[0080] The thickness of the sealant layer 5 is not particularly limited and can be set appropriately according to the required properties. For example, the thickness of the sealant layer 5 may be 15 to 200 μm, 30 to 200 μm, or 50 to 200 μm. By increasing the thickness of the sealant layer 5, sufficient opacity and light shielding can be ensured while keeping the concentration of the white pigment low.

[0081] The sealant layer 5 may be a layer consisting of one or more sealant films. The sealant film may be, for example, an unoriented resin film. The method for forming the sealant film is not particularly limited, and known methods such as the inflation method and melt molding methods such as the T-die extrusion method are preferably used.

[0082] When the sealant layer 5 contains a white pigment, a masterbatch in which the white pigment is pre-mixed into the polyolefin resin may be used when forming the sealant film. The white pigment concentration of the masterbatch may be, for example, about 40 to 70% by mass. When using a masterbatch, the desired blending ratio may be adjusted by kneading the masterbatch with the polyolefin resin.

[0083] Although one embodiment of the laminate of the present disclosure has been described above, the laminate of the present disclosure is not limited to the above embodiment.

[0084] Furthermore, the laminate may further comprise one or more other layers (e.g., films) to provide the mechanical strength and other functions required for a packaging bag. The location of the other layers is not particularly limited. For example, the other layers may be provided between the first base material layer 1 and the printed layer 2, or between the printed layer 2 and the adhesive layer S1. That is, the first base material layer 1 and the printed layer 2 may or may not be adjacent. Similarly, the printed layer 2 and the adhesive layer S1 may or may not be adjacent.

[0085] The laminates of this disclosure can be suitably used to form packaging bags (e.g., flexible bags) for packaging contents. Laminates including a sealant layer can be used as packaging material as is.

[0086] <Packaging material> The packaging material, for example, includes a sealant layer in its innermost layer. The packaging material may consist of the laminate described above, or it may be a processed version of said laminate. The packaging material is preferably used to form a packaging bag (e.g., a flexible bag) for packaging the contents.

[0087] <Packaging bag> A packaging bag is made by forming a bag from the packaging material described above. For example, a packaging bag can be manufactured by bonding the sealant layers of a pair of packaging materials together and then forming the bag. Alternatively, a packaging bag can be manufactured by folding a single piece of packaging material so that the sealant layers face each other and then forming the bag.

[0088] Examples of packaging bags include flat pouches and self-standing pouches.

[0089] A flat pouch-shaped packaging bag may be formed by folding a single sheet of packaging material (including a sealant layer) in half so that the sealant layers face each other, and then heat-sealing three sides, or by stacking two sheets of packaging material (including a sealant layer) so that the sealant layers face each other, and then heat-sealing all four sides.

[0090] A self-standing packaging bag may be formed by, for example, placing the sealant layers of two packaging materials (packaging materials including a sealant layer) facing each other, and inserting one more packaging material (packaging material including a sealant layer) folded in half with the sealant layer facing outwards between these layers, thereby stacking a total of three packaging materials, and then heat-sealing all four sides to form a bag shape.

[0091] The packaging bag may be for boiling or retorting. The laminate of this disclosure has a water-based ink layer, but the second base material layer has barrier properties, so even when subjected to (pressurized) hot water treatment such as boiling or retorting, the adhesion of odors (chlorine odor) to the contents is suitably suppressed.

[0092] <Package> The packaging comprises the aforementioned packaging bag and the contents contained within the packaging bag. Examples of contents include liquids such as liquid seasonings, toiletries, soups, and liquid detergents; solids such as boiled dishes; and solid-liquid mixtures of liquids and solids such as curry. [Examples]

[0093] The present disclosure will be further described in detail by the following examples and comparative examples, but the present disclosure is not limited to these examples.

[0094] <Preparation of various materials> (First base layer / printing layer) A test chart pattern with a gradation pattern (thickness: 1-2 μm) was created on a PET film (Toyobo Co., Ltd., E5102, thickness 12 μm) by flexographic printing using water-based flexographic printing inks (Toyo Ink, Aquariona (red, yellow, cyan, black)). A further white layer (thickness: 1-2 μm) was then created on top of the pattern by flexographic printing using water-based white ink (Toyo Ink Co., Ltd., Aquariona white), thereby forming a printed layer. The thickness of the printed layer was 2-4 μm. In the table, those obtained in this way are indicated as "with white layer". Distilled water or tap water was used as dilution water during the water-based printing of the pattern and white layer. The chlorine concentration of the dilution water was measured using a residual chlorine meter. A printed layer was formed on a PET film (Toyobo Co., Ltd., E5102, 12 μm thick) by flexographic printing using water-based flexographic inks (Toyo Ink, Aquariona (red, yellow, cyan, black)) to create a test chart pattern with a gradation pattern (thickness: 1-2 μm). The thickness of the printed layer was 1-2 μm. In the table, the result obtained in this way is indicated as "no white layer". GL-ARH, manufactured by TOPPAN Co., Ltd., was used as the PET film (12 μm thick) having a transparent barrier layer (aluminum oxide vapor-deposited layer, 9 nm thick). A printed layer (2-3 μm thick) was formed on the transparent barrier layer side of this PET film in the same manner as in the case with a "white layer".

[0095] (Second base layer) As a nylon film (15 μm thick) having a transparent barrier layer (silica vapor-deposited layer, 30 nm thick), GL-EY film manufactured by TOPPAN Co., Ltd. was used. In the table, the position indicated for the vapor-deposited layer shows that the vapor-deposited layer is formed in that orientation on the second substrate layer. As a PET film (12 μm thick) with an aluminum vapor-deposited layer (50 nm thick), we used BR-PET1012 film manufactured by Toray Industries, Inc. • Unitika's Emblem ON nylon film (15μm thick) was used.

[0096] (Sealant layer) • As the CPP film (60 μm thick), we used ZK207#60 manufactured by Toray Film Processing Co., Ltd. White CPP film (60 μm thick) was prepared as follows: 92.0 parts by mass of propylene-ethylene block copolymer, 8.0 parts by mass of ethylene-α-olefin copolymer, and 5 parts by mass of titanium dioxide as a white pigment were pre-mixed by dry blending. The resulting pre-mixture was kneaded at 200-230°C using a continuous kneading extruder and pelletized. The resulting pellets were then fed into an extruder, heated to 220°C, and then a sealant film was produced by extrusion inflation molding using an inflation apparatus. • As the LLDPE film (100 μm thick), SE620 manufactured by Tamapoly Co., Ltd. was used.

[0097] (1st / 2nd adhesive layer) • As a solvent-based adhesive, DIC Corporation's LX-500 / KW-75 was used. As a solvent-free adhesive, we used EA-N6008 / EA-N5618 manufactured by Toyo Morton Co., Ltd.

[0098] <Fabrication of laminates> As shown in Table 1, each film is coated with adhesive (coating amount: 2g / m²). 2 A laminate was fabricated by bonding the layers together, with the layers in the following order: first substrate layer / printed layer / first adhesive layer / second substrate layer / second adhesive layer / sealant layer.

[0099] <Packaging preparation and evaluation of chlorine odor> Three sides of the laminate obtained in each example were sealed, water was filled in as the contents, and the remaining side was sealed to form a package. After the packaging was subjected to hot water treatment (boiling) under the following conditions, the packaging was opened and the chlorine odor of the water it contained was evaluated by five skilled subjects. The degree of chlorine odor was relatively evaluated on a scale from rank 1: weak chlorine odor to rank 4: strong chlorine odor. The results are shown in Table 1. Examples 1-8: 90°C / 30 minutes. Examples 9-12: 70°C / 10 minutes. Comparative example: 90°C / 30 minutes.

[0100] [Table 1] [Explanation of symbols]

[0101] 10...Laminate, 1...First base layer, 2...Printed layer, 3...Gas barrier layer, 4...Second base layer, 5...Sealant layer, S1...First adhesive layer, S2...Second adhesive layer.

Claims

1. The material comprises, in this order, a first substrate layer having a printing layer, a first adhesive layer, a second substrate layer having a gas barrier layer, a second adhesive layer, and a sealant layer. A laminate in which the aforementioned printing layer is a layer formed from water-based ink.

2. The laminate according to claim 1, wherein the first substrate layer has the printing layer on the side facing the first adhesive layer.

3. The laminate according to claim 1, wherein the gas barrier layer comprises an inorganic oxide vapor deposition layer or a metal vapor deposition layer.

4. The laminate according to claim 1, wherein the sealant layer contains a white pigment.

5. The laminate according to claim 1, wherein the first adhesive layer and the second adhesive layer are layers formed from a solvent-free adhesive.

6. A packaging material comprising a laminate according to any one of claims 1 to 5.

7. A packaging bag made by forming a bag from the packaging material described in claim 6.

8. A packaging bag according to claim 7, which is for boiling or retorting.

9. A packaging body comprising a packaging bag according to claim 7 and contents contained in the packaging bag.

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