Soft packaging sheets, packaging materials

Abstract

To provide a flexible packaging material sheet that is unlikely to cause defect such as misalignment, blurring, and dropping in a printed image even when a force such as friction or impact is applied through a surface protective layer, or when it is greatly deformed in water, in a flexible packaging material sheet including at least the surface protective layer, a printing ink layer, a barrier layer made of a metal foil, and a sealant layer.SOLUTION: A printing anchor coat layer 12 containing a saturated copolymerized polyester resin having a glass transition temperature of -30 to 60°C is interposed between a printing ink layer 11 and a barrier layer 13.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a soft packaging sheet and a package formed by filling a bag-shaped container made of the soft packaging sheet with contents. [Background technology]

[0002] Conventionally, products that require long-term storage, such as foods, medicines, and chemicals, have been distributed on the market, for example, as solid packages that are placed in molded containers with an opening at the top and then heat-sealed with a lid, or as packages that are sealed in bag-shaped containers (flexible packaging containers) made of various types of soft packaging sheets.

[0003] As a soft packaging sheet, for example, Patent Document 1 describes a sheet having at least a surface protection layer, a barrier layer made of aluminum foil, and a sealant layer made of a heat-sealable resin film. The document also discloses a package in which the sheet is processed into a rectangular shape, then folded in half with the sealant layer on the inside, and the left and right edges are side-sealed to form a bag-like container with an upper opening, and the contents are then placed in the container and the opening is top-sealed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-199268 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, a printed ink layer is sometimes provided on the upper surface of the barrier layer of the flexible packaging sheet that constitutes the surface of the package for the purpose of displaying information about the contents or arranging designs such as advertisements. However, depending on the storage environment and usage conditions of the flexible packaging sheet and the package made using the same, defects such as misalignment, fading, and falling off of the printed image (hereinafter sometimes simply referred to as printing defects) may occur, and these printing defects may also be caused by moisture that comes into contact with the surface of the flexible packaging sheet or the flexible package.

[0006] For example, when the contents are food, medicine, chemicals, etc. that are easily altered or deteriorated even at room temperature, the package is stored at a low temperature of about 10°C or less. At this time, if the humidity is high, condensation occurs on the surface of the package, and this condensed water permeates into the interior of the soft packaging sheet over time and also into the interface between the printing ink layer and the barrier layer, which may cause a situation in which the adhesion between the two layers is reduced. As a result, when the package is transported on a belt conveyor after storage, packed in a cardboard box, or displayed in a store after opening, if external forces such as strong friction and impact are applied to the surface of the package, or the package itself is significantly deformed, the above-mentioned printing defects may occur on the surface, damaging the appearance. Therefore, it is considered ideal that the soft packaging sheet constituting the soft packaging body does not develop the above-mentioned printing defects caused by such external forces and deformations, even in water.

[0007] Based on the above concept, the present inventors have set an object of the present invention to provide a flexible packaging sheet comprising at least a surface protective layer, a printed ink layer, a barrier layer made of a metal foil, and a sealant layer, in which the printed ink layer is unlikely to suffer printing defects such as displacement, scratching, or falling off even when the surface protective layer is subjected to external forces such as friction or impact, or is deformed while immersed in water for a certain period of time. [Means for solving the problem]

[0008] As a result of investigations, the present inventors have found that the above-mentioned printing defects are unlikely to occur in the flexible packaging sheet by forming the surface protective layer of the flexible packaging sheet with an overprint coating agent, by interposing a printed anchor coating layer between the printed ink layer and the barrier layer, and by using a saturated copolymer polyester resin having a glass transition temperature in a specified range as the anchor coating agent that forms this layer, and have thus completed the present invention. That is, the present invention relates to the following flexible packaging sheet and package.

[0009] 1) A flexible packaging sheet used to prepare a package in which contents are placed in a bag-shaped container, the flexible packaging sheet comprising, in order from the outside, at least an overprint coating layer, a printed ink layer, a printed anchor coating layer, a barrier layer made of metal foil, and a sealant layer made of a heat-fusible resin, the anchor coating agent constituting the printed anchor coating layer comprising a saturated copolymer polyester resin having a glass transition temperature of -30°C to 60°C.

[0010] 2) The flexible packaging sheet according to 1), wherein the overcoat agent constituting the overprint coat layer is a cellulose-based overcoat agent.

[0011] 3) The flexible packaging sheet according to 1) or 2), wherein a reinforcing layer made of a synthetic resin film is disposed between the barrier layer and the sealant layer.

[0012] 4) A sealed package obtained by placing contents in a bag-like container made of a soft packaging sheet of any one of 1) to 3) and then heat-sealing the opening edge of the bag-like container. Effect of the Invention

[0013] The flexible packaging sheet in 1) is characterized in that the surface protective layer is composed of an overprint coating agent, and the printed anchor coating layer interposed between the printed ink layer and the barrier layer is formed from an anchor coating agent made of a saturated copolymer polyester resin with a glass transition temperature of -30°C to 60°C. Even if the surface protective layer is subjected to external forces such as friction or impact, or is deformed by being immersed in water for a certain period of time, the printed ink layer is less likely to suffer printing defects such as displacement, peeling, and falling off.

[0014] 2) The soft packaging sheet has an overprint coating layer made of a cellulose-based overcoat agent and has high water resistance, so that printing defects are less likely to occur in packages made of this soft packaging sheet.

[0015] In the flexible packaging sheet 3), a reinforcing layer made of a synthetic resin film is disposed between the barrier layer and the sealant layer, and since the reinforcing layer increases the overall strength, the package made of this flexible packaging sheet is less likely to have printing defects. In addition, the reinforcing layer enhances the so-called dead hold property of this flexible packaging sheet, and since it hardly returns to its original shape even when folded for processing, it is easy to produce bag-shaped containers of complex shapes.

[0016] The package 4) is a sealed product obtained by putting contents into a bag-like container made of any one of the soft packaging sheets 1) to 3) and then heat-sealing the opening edge of the bag-like container, and even if water comes into contact with the surface and external forces such as friction or impact force or large deformation are applied, the printing defects are unlikely to occur, and this effect is particularly good in the soft packaging sheet 2). Furthermore, among the packages 4), those using the soft packaging sheet 3) have the overall strength of the soft packaging sheet increased by a specified reinforcing layer and are also excellent in dead hold, so that they are even better at preventing printing defects and are also excellent in shape retention. [Brief description of the drawings]

[0017] [Figure 1] 1 is a cross-sectional view of a flexible packaging sheet according to the present invention. [Diagram 2]1 is a perspective view of a bag-shaped container according to the present invention; [Diagram 3] 1 is a perspective view of a package of the present invention and a cross-sectional view of an opening. [Figure 4] FIG. 1 is a conceptual diagram of a print defect evaluation device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The flexible packaging sheet (1) according to the present invention, the bag-shaped container (2) made of the flexible packaging sheet (1), and the package (3) filled with the contents (C) will be described in detail below with reference to Figures 1 to 3. However, the scope of the present invention is not limited to these drawings.

[0019] FIG. 1 is a cross-sectional view of a flexible packaging sheet (1). The embodiment of Fig. 1(a) comprises an overprint coat layer (10) as the outermost layer, a printed ink layer (11), a printed anchor coat layer (12), a barrier layer (13), an adhesive layer (14), a reinforcing layer (15), an inner anchor coat layer (16), and a sealant layer (17) as the innermost layer. In this embodiment, the printed ink layer (11) is an intermittent layer, and the overprint coat layer (10) is partially adhered to the printed anchor coat layer (12). The adhesive layer (14), the reinforcing layer (15), and the inner anchor coat layer (16) are optional and can be omitted. The embodiment in FIG. 1(b) is an embodiment in which the printed ink layer (11) in the flexible packaging sheet (1) in FIG. 1(a) is made to be a continuous layer. The embodiment in FIG. 1(c) is an embodiment in which the reinforcing layer (15) and the inner anchor coat layer (16) in the flexible packaging sheet (1) in FIG. 1(b) are omitted.

[0020] The overprint coat layer (10) is a protective layer and a water-resistant layer for the flexible packaging sheet (1). This overprint coat layer (10) makes it difficult for water that comes into contact with the surface of the package (3) to reach the printed ink layer (12), and also prevents printing defects in the printed ink layer (12) caused by external forces or deformations applied to the surfaces of the flexible packaging sheet (1) and the package (3), and also prevents defects such as cracks and pinholes in the barrier layer (13) caused by these. The overprint coating layer (10) is composed of any of various known overcoat agents. The overcoat agent is a composition obtained by dissolving any of various known binder resins in a solvent, and may contain a curing agent (described below) and other functional additives (described below). The binder resin may be at least one selected from the group consisting of animal-based overcoating agents such as shellac resin, synthetic resin-based overcoating agents, and cellulose-based overcoating agents. Examples of synthetic resin-based overcoating agents include epoxy resins, polyurethane resins, chlorinated polyolefin resins, acrylic resins, vinyl chloride-vinyl acetate copolymers, and polyester resins (unsaturated copolymer polyester resins, saturated copolymer polyester resins, etc.). Examples of cellulose-based overcoating agents include nitrocellulose, cellulose acetate, cellulose propionate, and cellulose acetate-butyrate. Among these, cellulose-based overcoating agents are preferred in terms of good water resistance and excellent print defect prevention, and nitrocellulose and / or cellulose acetate are particularly preferred. Examples of the solvent include toluene, xylene, acetone, methyl ethyl ketone, ethyl acetate, butyl acetate, methanol, ethanol, and isopropyl alcohol (hereinafter, the same applies when referring to the solvent). Examples of the curing agent include polyisocyanates, polyepoxy compounds, polyoxazoline compounds, ketimine compounds, and melamine compounds (hereinafter, the same applies when referring to a curing agent). The overprint coat layer (10) can be formed by applying an overcoat agent to the printing ink layer (11) and drying it usually at 80 to 170° C. The amount of coating is not particularly limited, and is usually 0.3 to 1 g / m, for example.2 , preferably 0.4 to 0.7 g / m 2 That's fine. The number of layers in the overprint coating layer (10) is not limited, and it may be a single coat or a multi-coat of two or more layers. The multi-coat may be composed of the same type of overcoat agent or may be composed of two or more types of overcoat agents. The thickness of the overprint coating layer (10) is not particularly limited, and is usually 0.3 to 2 μm, preferably 0.4 to 1.5 μm, in consideration of ensuring the strength as a protective layer and the barrier function as a water-resistant layer.

[0021] The printing ink layer (11) is a layer that provides information about the contents (C) and a design on the surfaces of the soft packaging sheet (1), the bag-shaped container (2), and the package (3), and is made of various known printing inks. The printing ink is a composition containing a colorant and a binder resin, and includes both active energy ray non-curable and curable inks. Examples of the coloring agent include pigments and / or dyes. Examples of the pigments include organic or inorganic pigments such as titanium dioxide, zinc oxide, gloss white, parlite, barium carbonate, calcium carbonate, precipitated silica, aerosil, talc, alumina white, mica, synthetic calcium silicate, magnesium carbonate, barium carbonate, carbon black, magnetite, and red iron oxide. The size of the pigment is not particularly limited, and the average primary particle size is usually 0.1 to 5 μm, preferably 0.5 to 3 μm. On the other hand, examples of the dyes include anthraquinone dyes, azo dyes, and quinoline dyes. The content of the coloring agent is not particularly limited, and the content is usually 0.5 to 40% by weight, preferably 2 to 10% by weight. Examples of the binder resin include active energy ray non-curable binder resins and / or active energy ray curable binder resins. Examples of the former binder resins include shellac resins, nitrocellulose, cellulose acetate, cellulose propionate, cellulose acetate butyrate, epoxy resins, polyurethane resins, chlorinated polyolefin resins, polyamide resins, acrylic resins, vinyl chloride-vinyl acetate copolymers, and polyester resins (unsaturated copolymer polyester resins, saturated copolymer polyester resins, etc.). Examples of the latter binder resins include various known poly(meth)acrylates such as di(meth)acrylates, tri(meth)acrylates, and tetra(meth)acrylates, as well as (meth)acrylates having 5 to 6 (meth)acryloyl groups in the molecule. The poly(meth)acrylates include various known modified poly(meth)acrylates such as urethane (meth)acrylates, epoxy (meth)acrylates, and polyester (meth)acrylates. Examples of the active energy rays include ultraviolet rays and electron beams. The printing ink may optionally contain a solvent, a curing agent, a polymerization initiator, and other additives. In the case where the binder resin is an active energy ray curable type, the solvent may contain various known (meth)acrylates as reactive diluents. Examples of the polymerization initiator include photopolymerization initiators such as benzophenone-based initiators, acetophenone-based initiators, and benzoin-based initiators. Examples of the additives include surfactants, plasticizers, silane coupling agents, antistatic agents, and the like. The printed ink layer (11) can be formed by a known printing method such as gravure printing, offset printing, or flexographic printing, and may be either monochromatic or multicolor. The total thickness of the printed ink layer (11) is not particularly limited, and may be, for example, usually 0.5 to 4 μm, preferably 0.8 to 3 μm, from the viewpoint of preventing printing defects.

[0022] The printed anchor coat layer (12) is a layer that bonds the printed ink layer (11) and the barrier layer (13), and by interposing the printed anchor coat layer (12) between the two layers, even if water that has come into contact with the surface of the overprint coat layer (10) reaches the printed ink layer (11), the adhesion between the printed ink layer (11) and the barrier layer (13) is unlikely to decrease. Therefore, it is considered that the above-mentioned printing defects are unlikely to occur even if external forces such as friction or impact are applied to the surfaces of the soft packaging material sheet (1), the bag-like container (2), and the package (3) or if they are excessively deformed in water. The anchor coating agent constituting the printed anchor coating layer (12) (hereinafter also referred to as the outer surface side anchor coating agent) is made of a saturated copolymer polyester resin having a glass transition temperature (JIS K7121-2012) of -30°C or more and 60°C or less, and contains the above-mentioned solvent. The saturated copolymer polyester resin can be produced by various known methods. The constituent raw materials include polyols, polycarboxylic acids, hydroxycarboxylic acids, lactones, and unsaturated monomers. The polyols include aliphatic, alicyclic, and aromatic diols such as ethylene glycol, propylene glycol, butanediol, neopentyl glycol, diethylene glycol, polyethylene glycol, cyclohexanedimethanol, bisphenol A, and bisphenol A-alkylene oxide adducts, as well as tri- and tetraols such as glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, diglycerin, ditrimethylolpropane, and ditrimethylolethane. Examples of polycarboxylic acids include aliphatic, alicyclic or aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, adipic acid, azelaic acid, sebacic acid, maleic acid, maleic anhydride and fumaric acid, and tri- or tetracarboxylic acids such as trimellitic acid, trimellitic anhydride, pyromellitic acid and pyromellitic anhydride, which may be alcohol esters. Examples of the alcohol include methanol, ethanol and butanol. Examples of hydroxycarboxylic acids include p-hydroxybenzoic acid, p-hydroxyethoxybenzoic acid, citric acid, isocitric acid, malic acid and tartaric acid, and two or more of these can be used in combination. Examples of lactones include β-butyrolactone, δ-valerolactone and ε-caprolactone. Examples of unsaturated monomers (graft monomers) include acrylic acid, methacrylic acid, maleic acid and fumaric acid. If the glass transition temperature of the saturated copolymer polyester resin is less than -30°C, the printed anchor coat layer (12) becomes too soft, and if it exceeds 60°C, the printed anchor coat layer (12) becomes too hard, and in either case, printing defects tend to occur in the printed ink layer (12), particularly when the flexible packaging sheet (1) is treated in water. From this viewpoint, the glass transition temperature is preferably -20°C or higher and 40°C or lower. The glass transition temperature of the saturated copolymer polyester resin can be adjusted by various known means. For example, when it is desired to lower the glass transition temperature from the viewpoint of the constituent raw materials, an aliphatic polyol and / or an aliphatic polycarboxylic acid may be selected. When it is desired to increase the glass transition temperature, a tri- or tetraol and a tri- or tetracarboxylic acid may be selected. The glass transition temperature can also be adjusted by adjusting the molecular weight of the saturated copolymer polyester resin. Specifically, the molecular weight may be usually 8000 to 20000 in number average molecular weight (polystyrene equivalent value in gel permeation chromatography). As a means for adjusting the molecular weight, for example, a method of performing a polycondensation reaction under reduced pressure may be mentioned. The outer surface anchor coating agent may be either a one-component curing type or a two-component curing type, and may contain the above-mentioned curing agent. The outer anchor coating agent may contain functional additives. For example, by including a surfactant, the surface tension of the printed anchor coating layer (12) can be adjusted, making it possible to prevent printing defects (non-printed areas of the printing ink). Furthermore, by including a plasticizer, the hardness of the printed anchor coating layer (12) can be adjusted, making it possible to prevent the printing from smearing or falling off. Furthermore, by including a silane coupling agent, the adhesion between the printed anchor coating layer (12) and the barrier layer (13) is improved, making it possible to prevent printing defects. Examples of surfactants include anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants. Examples of plasticizers include aliphatic dicarboxylic acid alkyl esters, such as alkyl adipates, alkyl phosphates, and alkyl trimellitates. Examples of the silane coupling agent include γ-chloropropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyl-tris(β-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and γ-glycidoxypropyltrimethoxysilane, etc. The content of the additive is not particularly limited, and may usually be 0.1 to 4% by weight. The printed anchor coat layer (12) can be formed by applying an outer anchor coat agent to one side of the barrier layer (13) and drying it at, for example, 70 to 90° C. The amount of coating is not particularly limited, and is usually, for example, 1 to 5 g / m 2 , preferably 2 to 4 g / m 2 That's fine. The printing anchor coat layer (12) can suitably prevent printing defects if its water contact angle is usually 65 to 80°, and preferably 70 to 78°. This contact angle is a measurement value after 30 seconds have elapsed since 1 μL of water was dropped on the surface of the printing anchor coat layer (12), and can be measured with any of various known water contact angle meters. The thickness of the printed anchor coat layer (12) is not particularly limited, and taking into consideration prevention of printing defects and adhesion between the printed ink layer (11) and the printed anchor coat layer (12), it is usually 0.5 to 3 μm, preferably 0.8 to 2 μm.

[0023] The barrier layer (13) is a layer for protecting the contents (C) of the package (3) from gas, water vapor, light, etc., and is made of metal foil. Examples of the metal foil include aluminum foil, iron foil, stainless steel foil, copper foil, and nickel foil, and aluminum foil is preferred in consideration of the barrier function, formability, cost, etc. Examples of the aluminum foil include pure aluminum foil or aluminum alloy foil, and soft materials (O materials) are preferred, and in particular, 1000 series aluminum alloy foil O materials or 8000 series aluminum alloy foil O materials specified in JIS H4160 are preferred. When the metal foil has an appropriate surface roughness, the adhesion between the printed anchor coat layer (12) and the barrier layer (13) is improved and printing defects are less likely to occur. The surface roughness may be, for example, 0.05 μm to 1 μm in arithmetic mean roughness Ra (JIS B0601-2013). A base layer (not shown) made of a predetermined chemical conversion treatment liquid can be formed on the outer surface and / or inner surface of the metal foil. The chemical conversion treatment liquid can be, for example, a water-alcohol solution containing phosphoric acid, a chromium-based compound, a fluorine-based compound and / or a binder resin. The chromium-based compound can be chromate and / or a chromium (III) salt, the fluorine-based compound can be a metal salt of fluoride and / or a non-metal salt of fluoride, and the binder resin can be at least one resin selected from the group consisting of an acrylic resin, a chitosan derivative resin and a phenolic resin. The amount of the chemical conversion treatment liquid used is not particularly limited, and the amount of chromium attached on one side of the metal foil is usually 0.1 to 50 mg / m. 2 It is sufficient if the range is such that The thickness of the barrier layer (13) is not particularly limited, but taking into consideration the balance between the strength of the entire flexible packaging sheet (1) and the prevention of printing defects and dead hold properties, the thickness is usually 6 to 50 μm, preferably 10 to 35 μm.

[0024] The adhesive layer (14) is an optional layer used to prevent delamination between the barrier layer (13) and the sealant layer (17). For example, when a reinforcing layer (15) is provided on the flexible packaging sheet (1), the reinforcing layer (15) is bonded to the barrier layer (13) via the adhesive layer (14), which increases the strength of the flexible packaging sheet (1) as a whole and ultimately prevents printing defects. The adhesive layer (14) is made of various known adhesives. Specific examples include vinyl chloride-vinyl acetate copolymer adhesives, polyester resin adhesives (unsaturated copolymer polyester resins, saturated copolymer polyester resins, etc.), polyurethane resin adhesives, etc. Among them, polyurethane resin adhesives, particularly two-component curing polyurethane resin adhesives, are preferred in terms of adhesion between the barrier layer (13) and the adhesive layer (14). As the two-component curing polyurethane resin adhesive, in particular, two-component curing polyether-urethane resin adhesive and / or two-component curing polyester-urethane resin adhesive are suitable. All of these are composed of a base agent and a curing agent, and the base agent may be any of various known polyether polyols and / or polyester polyols, and the curing agent may be any of various known polyisocyanates. Examples of polyisocyanates include hexamethylene diisocyanate, isophorone diisocyanate, rylene diisocyanate, and diphenylmethane diisocyanate, as well as their derivatives (isocyanurate, biuret, adduct, etc.). The thickness of the adhesive layer (14) is not particularly limited, but taking into consideration the above-mentioned effect of preventing delamination, etc., it is usually 1 to 5 μm, preferably 2 to 3.5 μm.

[0025] The reinforcing layer (15) is an optional layer for increasing the overall strength of the flexible packaging sheet (1) to improve the prevention of printing defects and the dead hold properties, and is made of any of various known synthetic resin films. The synthetic resin film may be either oriented or non-oriented, and examples thereof include polyamide film, polyolefin film, and polyester film. Examples of polyamide films include 6-nylon film, etc. Examples of polyolefin films include high-density polyethylene film, medium-density polyethylene film, linear low-density polyethylene film, homopolypropylene film, poly(ethylene-propylene) random copolymer film, and polyethylene-polypropylene block copolymer film, etc., which may be acid-modified with maleic anhydride, vinyl acetate, etc. Examples of polyester films include polyethylene terephthalate film, polybutylene terephthalate film, polyethylene naphthalate film, and polybutylene naphthalate film, etc. Among synthetic resin films, polyester film increases the overall strength of the flexible packaging sheet (1), making it difficult for printing defects to occur even if the flexible packaging sheet (1), the bag-like container (2), or the package (3) is significantly deformed, and also improves the deadhold properties of the flexible packaging sheet (1). From this viewpoint, oriented polyester film is particularly preferable as the polyester film. The thickness of the reinforcing layer (15) is not particularly limited, but from the viewpoints of preventing printing defects and dead hold properties, it is usually 10 to 50 μm, preferably 10 to 35 μm.

[0026] The inner anchor coat layer (16) is an optional layer used for the purpose of bonding the reinforcing layer (15) and the sealant layer (17), and any known anchor coat agent that achieves this purpose (hereinafter also referred to as the inner anchor coat agent) can be used without particular restriction. Specifically, the inner anchor coating agent may be a polyester resin-based anchor coating agent and / or an adhesive. The former anchor coating agent may be either a one-component curing type or a two-component curing type, and is useful when the sealant layer (17) is made of a hot melt adhesive described below, and may be the same as the outer anchor coating agent that forms the printed anchor coating layer (12). The latter adhesive is useful when the sealant layer (17) is made of a heat-sealable resin film described below, and may be the same as the adhesive that forms the adhesive layer (14), and may be a two-component curing polyether-urethane resin-based adhesive and / or a two-component curing polyester-urethane resin-based adhesive. The thickness of the inner anchor coat layer (16) is not particularly limited, but from the viewpoint of adhesion to the sealant layer (17), it is usually 1 to 5 μm, preferably 2 to 3.5 μm.

[0027] The sealant layer (17) constitutes the innermost layer of the soft packaging sheet (1) and also constitutes the inner surface of the package (3), and is made of any of various known hot melt adhesives and / or heat-sealable resin films.

[0028] The hot melt adhesive may be a composition containing a base resin, a wax, and a tackifier resin. Examples of the base resin include polyolefin resins and ethylene-vinyl acetate copolymers, and examples of the polyolefin resin include high-density polyethylene, medium-density polyethylene, linear low-density polyethylene, homopolypropylene, poly(ethylene-propylene) random copolymers, and polyethylene-polypropylene block copolymers. Examples of the vinyl acetate copolymer include ethylene-ethyl acrylate-vinyl acetate copolymers. Examples of the tackifier resin include rosins such as rosin, disproportionated rosin, hydrogenated rosin, and polymerized rosin, as well as esters of rosins with polyhydric alcohols such as glycol, glycerin, and pentaerythritol, and hydrocarbon resins having terpene and / or styrene as constituent monomers. Examples of the wax include polyethylene wax, polypropylene wax, silicon wax (silicone wax), fluorine wax, and amide wax. The sealant layer (17) can be formed from a hot melt adhesive by using a hot applicator or a gravure coater.

[0029] The heat-sealable resin film may be either a non-stretched type or a stretched type, and examples of the heat-sealable resin constituting this film include polyolefin resin, polyester resin, polyvinyl resin, polysulfone resin, etc. Examples of the polyolefin resin include polypropylenes such as homopolypropylene, block polypropylene, random polypropylene, and acid-modified polypropylene, polyethylenes such as low-density polyethylene, linear low-density polyethylene, and high-density polyethylene, and polyethylene-propylenes such as poly(ethylene-propylene) random copolymers and polyethylene-polypropylene block copolymers. Examples of the polyester resin include polyethylene terephthalate resin and polybutylene terephthalate resin. Examples of the polyvinyl resin include polystyrene resin. The heat-sealable resin film may be a single layer or a multilayer. The multilayer heat-sealable resin film may be a combination of two or more single-layer heat-sealable resin films of the same resin type, or a combination of two or more single-layer heat-sealable resin films of different resin types. Specifically, examples include a multilayer film obtained by co-extrusion of one or more of the above heat-sealable resins, and a multilayer sealant film obtained by combining, for example, a film made of the above polypropylenes and a film made of the above polyvinyl resin in any order. The heat-sealable resin film is preferably one that can be cohesively peeled off when the package (3) is opened (see FIG. 3(c)). For example, a low-density polyethylene resin film is preferable, and an additive-free one is particularly preferable.

[0030] The thickness of the sealant layer (17) is not particularly limited, but in consideration of the sealing accuracy and sealing strength, it is usually 10 to 60 μm, preferably 24 to 45 μm.

[0031] The flexible packaging sheet (1) can be produced by various known methods, such as dry lamination, melt extrusion lamination, heat lamination, gravure coating, etc. These methods may be combined.

[0032] The package (3) of the present invention is obtained by placing contents (C) in a bag-shaped container (2) made from a soft packaging sheet (1) and then sealing the bag-shaped container by heat sealing.

[0033] The bag-shaped container (2) has an opening (21), an opening edge (22), and a body (23). The body (23) has its periphery sealed with at least one linear seal portion (24) to form a storage section.

[0034] FIG. 2 is a perspective view of the bag-shaped container (2). The bag-shaped container (2) in FIG. 2(a) is made by folding a rectangular soft packaging sheet (1) in half horizontally with the sealant layer (17) on the inside, and has two linear seal portions (24) on the side and bottom. The bag-shaped container (2) in FIG. 2(b) is made by folding a rectangular soft packaging sheet (1) in half lengthwise with the sealant layer (17) on the inside, and providing a total of two linear seal portions (24) on both sides. The bag-shaped container (2) in Figure 2(c) is made by overlapping two rectangular soft packaging sheets (1) of the same dimensions with their sealant layers (17) facing each other, and has linear seal portions (24) provided in a total of three places on both sides and the bottom. The bag-shaped container (2) in FIG. 2(d) is an embodiment in which two air chambers are formed by providing one linear seal part (24) in the widthwise center of the bag-shaped container (2) in FIG. 2(c). The bag-shaped container (2) in FIG. 2(e) is one type of gusset bag, with both sides folded inward and a palm-shaped linear seal portion (24) provided on the body portion (23) on the rear side. The bag-shaped container (2) in FIG. 2(f) is one embodiment of a standing pouch, and is formed with a bottom portion (25) that enables the bag-shaped container to stand on its own. The above are all examples, and in each embodiment, the overall shape of the container and the number and shape of the storage sections are not limited.

[0035] One embodiment of the manufacturing method is shown by taking the bag-shaped container (2) of FIG. 2(f) as an example. First, a rectangular soft packaging sheet (1) cut to a predetermined size is formed with a single bellows-folded portion in the horizontal direction in the vertical center of the sheet. A central valley fold is formed in the bellows-folded portion, and a mountain fold and a valley fold are formed above the central valley fold, each of the same width, and a mountain fold and a valley fold are also formed below the central valley fold, each of the same width. Next, the soft packaging sheet (1) is folded in the middle at the central valley fold so that the sealant layer (17) is on the inside. Next, both sides of the soft packaging sheet (1) folded in half in this way are heat-sealed to form a linear seal portion (24). After that, the central fold is opened to the left and right to obtain a three-sided bag-shaped container (2) as shown in FIG. 2(f).

[0036] The package (3) is a sealed body formed by filling the storage portion of the bag-like container (2) with the contents (C) and then heat-sealing (linear sealing) the opening edges (23) together.

[0037] The contents (C) are not particularly limited, and may be food or non-food. Examples of food include cream cheese, butter, jelly, yokan, pudding, miso, curry, pasta sauce, juice, dressing, etc. Examples of non-food include industrial products such as glue, sealant, and clay, as well as medicines and chemicals. Other sanitary products such as napkins, gauze, and cotton can also be the contents (C). Note that the contents (C) are preferably soft materials, flowable materials, or liquid materials, but are not limited to these forms.

[0038] FIG. 3 is a perspective view of the package (3) and a partial cross-sectional view of the opening portion (26) thereof. The package (3) in FIG. 3(a) is a package made of the bag-shaped container (2) in FIG. 2(f) that is filled with the contents (C) and then the opening edge (22) The contents (C) are flattened into a block shape, and examples of such contents include food products such as cream cheese, butter, and jelly. The package (3) is sealed with linear seals (24) at three locations, on both sides and at the top, making it possible to maintain the quality of the contents (C) for a long period of time. The opening portion (26) of the package (3) functions as a tab by folding both of the two opening edges (22) inward. This tab may be formed after the bag-shaped container (2) is produced, or may be formed in advance in the soft packaging sheet (1). Fig. 3(b) is a partial cross-sectional view of the opening portion (26) of the package (3) in Fig. 3(a) before opening. As shown in this figure, this opening portion (26) forms a heat-sealed zone by heat-sealing the sealant layers (17) together. For convenience, the printing ink layer (11) is omitted in this figure. Figure 3(c) shows the failure mode of the sealant layer (17) during the process of opening the package (3) in Figure 3(a). This failure mode is cohesive failure, and the easy opening is made possible by the progress of this failure within the layer as the package is opened. Note that the easy opening may also be achieved by interfacial failure at the heat-sealed interface between the sealant layers (17) (not shown). For the sake of convenience, the printing ink layer (11) is also omitted in this figure. After opening, the contents (C) are removed and used for their intended purpose.

[0039] The package (3) in Fig. 3(a) is stored in a refrigerated state after, for example, storing the top seal part and both side seal parts in an outer box. At this time, condensation may occur on the surface of the package (3). However, as already described, the flexible packaging sheet (1) constituting the package (3) has a predetermined layer structure, and even if the condensed water penetrates into the overprint coat layer (10) and reaches the printed ink layer (11), the printed ink layer (11) is bonded to the barrier layer (13) via the printed anchor coat layer (12), so that it is difficult to peel off or fall off from the barrier layer (13). Therefore, even if some external force is applied to the surface of the package (3) when it is transported or packed after refrigerated storage, it is considered that defects such as blurring, displacement, or falling off of the printed image are unlikely to occur. EXAMPLES

[0040] The present invention will be described in more detail below through examples and comparative examples, but the technical scope of the present invention is not limited to these specific examples.

[0041] <Preparation of soft packaging sheet (1)> Example 1 A one-part curing type outer surface anchor coating agent consisting of a solution of saturated copolymer polyester resin with a glass transition temperature of -28°C was applied to one side of a 12μm thick aluminum foil (A8021H-O) with a roll coater so that the thickness after curing was about 1.0μm, and the coating was dried at 70°C for 30 seconds to form a printed anchor coating layer. Next, white printing ink (pigment: titanium dioxide, binder resin: vinyl chloride-vinyl acetate copolymer. The same applies below.) was applied to this printed anchor coating layer with a roll coater so that the thickness after drying was about 2.0μm, forming a printed ink layer. Next, a nitrocellulose solution was applied to this printed ink layer with a roll coater so that the thickness after drying was about 1.0μm, and the coating was dried at 80°C for 1 minute to form an overprint coating layer. Next, a two-component curing polyester-urethane resin adhesive (hereinafter also referred to as two-component PU) was applied to the other side of the aluminum foil with a roll coater so that the thickness after curing was 3.0 μm, and the adhesive layer was formed by drying at 100 ° C for 1 minute. Next, a stretched polyester film (hereinafter also referred to as PET film) with a thickness of about 12 μm was bonded to this adhesive layer, and then aging treatment was performed at 40 ° C for 72 hours to form a reinforcing layer. Next, a commercially available one-component curing polyester resin anchor coating agent (hereinafter also referred to as one-component AC) was applied to this PET film as an inner side anchor coating agent with a roll coater so that the film thickness after drying was about 3.0 μm, and the inner side anchor coating layer was formed by drying at 80 ° C for 1 minute. Next, a hot melt adhesive (base resin: ethylene-vinyl acetate copolymer, tackifier resin: rosins) (hereinafter also referred to as HM adhesive) was applied to this anchor coat layer using a roll coater so that the thickness after cooling would be approximately 30 μm, thereby forming a sealant layer, thereby producing the soft packaging sheet A1.

[0042] Example 2 Flexible packaging sheet A2 was produced in the same manner as flexible packaging sheet A1, except that the inner anchor coat layer was made of an adhesive consisting of two-component PU (film thickness after curing: approximately 3.0 μm; the same applies below), and the sealant layer was made by laminating an approximately 30 μm-thick additive-free low-density polyethylene film (hereinafter also referred to as LDPE film).

[0043] Example 3 A flexible packaging material sheet B was produced in the same manner as the flexible packaging material sheet A1, except that the printed anchor coat layer was formed from a solution of a saturated copolymer polyester resin having a glass transition temperature of 35°C.

[0044] Example 4 A flexible packaging material sheet C was produced in the same manner as the flexible packaging material sheet A1, except that the printed anchor coat layer was formed from a solution of a saturated copolymer polyester resin having a glass transition temperature of 58°C.

[0045] Example 5 A flexible packaging sheet D1 was produced in the same manner as the flexible packaging sheet A1, except that a cellulose acetate solution was used as the overcoat agent and the outer anchor coat layer was composed of a solution of saturated copolymer polyester resin having a glass transition temperature of -28°C.

[0046] Example 6 A flexible packaging sheet D2 was produced in the same manner as the flexible packaging sheet D1, except that the inner anchor coat layer was made of an adhesive made of two-component PU and the sealant layer was made of an LDPE film.

[0047] Example 7 A flexible packaging sheet E1 was produced in the same manner as the flexible packaging sheet D1, except that the printed anchor coat layer was formed from a solution of a saturated copolymer polyester resin having a glass transition temperature of -17°C.

[0048] Example 8 A flexible packaging sheet E2 was produced in the same manner as the flexible packaging sheet E1, except that the inner anchor coat layer was made of an adhesive made of two-component PU and the sealant layer was made of an LDPE film.

[0049] Example 9 A flexible packaging sheet F1 was produced in the same manner as the flexible packaging sheet D1, except that the printed anchor coat layer was formed from a solution of a saturated copolymer polyester resin having a glass transition temperature of 3°C.

[0050] Example 10 A flexible packaging sheet F2 was produced in the same manner as the flexible packaging sheet F1, except that the inner anchor coat layer was made of an adhesive made of two-component PU and the sealant layer was made of an LDPE film.

[0051] Example 11 A flexible packaging sheet G1 was produced in the same manner as the flexible packaging sheet D1, except that the printed anchor coat layer was formed from a solution of a saturated copolymer polyester resin having a glass transition temperature of 8°C.

[0052] Example 12 A flexible packaging material sheet G2 was produced in the same manner as in the flexible packaging material sheet G1 of Example 11, except that the inner anchor coat layer was made of an adhesive made of two-component PU and the sealant layer was made of an LDPE film.

[0053] Example 13 A flexible packaging sheet H was produced in the same manner as the flexible packaging sheet D1, except that the printed anchor coat layer was made of a solution of a saturated copolymer polyester resin having a glass transition temperature of 35°C.

[0054] Example 14 A flexible packaging material sheet I was produced in the same manner as in the flexible packaging material sheet D1, except that the printed anchor coat layer was formed from a solution of a saturated copolymer polyester resin having a glass transition temperature of 57°C.

[0055] Comparative Example 1 A flexible packaging material sheet J was produced in the same manner as the flexible packaging material sheet A1, except that the printed anchor coat layer was formed from a solution of a saturated copolymer polyester resin having a glass transition temperature of -34°C.

[0056] Comparative Example 2 A flexible packaging material sheet K1 was produced in the same manner as the flexible packaging material sheet A1, except that the printed anchor coat layer was formed from a solution of a saturated copolymer polyester resin having a glass transition temperature of 67°C.

[0057] Comparative Example 3 A flexible packaging sheet K2 was produced in the same manner as the flexible packaging sheet K1, except that the inner anchor coat layer was made of an adhesive made of two-component PU and the sealant layer was made of an LDPE film.

[0058] Comparative Example 4 A flexible packaging sheet L1 was produced in the same manner as in the flexible packaging sheet J, except that the printed anchor coat layer was composed of a solution of vinyl chloride-vinyl acetate copolymer having a glass transition temperature of 70°C.

[0059] Comparative Example 5 A flexible packaging sheet L2 was produced in the same manner as the flexible packaging sheet L1, except that the inner anchor coat layer was made of an adhesive made of two-component PU and the sealant layer was made of an LDPE film.

[0060] Comparative Example 6 A flexible packaging material sheet M was produced in the same manner as in the flexible packaging material sheet D1, except that the printed anchor coat layer was formed from a solution of a saturated copolymer polyester resin having a glass transition temperature of -34°C.

[0061] Comparative Example 7 A flexible packaging sheet N1 was produced in the same manner as the flexible packaging sheet M, except that the printed anchor coat layer was made of a solution of a saturated copolymer polyester resin having a glass transition temperature of 67°C.

[0062] Comparative Example 8 A flexible packaging sheet N2 was produced in the same manner as the flexible packaging sheet N1, except that the inner anchor coat layer was made of an adhesive made of two-component PU and the sealant layer was made of an LDPE film.

[0063] Comparative Example 9 A flexible packaging sheet O1 was produced in the same manner as in the flexible packaging sheet M, except that the printed anchor coat layer was composed of a solution of vinyl chloride-vinyl acetate copolymer having a glass transition temperature of 5°C.

[0064] Comparative Example 10 A flexible packaging sheet O2 was produced in the same manner as the flexible packaging sheet O1, except that the inner anchor coat layer was made of an adhesive made of two-component PU and the sealant layer was made of an LDPE film.

[0065] Comparative Example 11 A flexible packaging sheet P1 was produced in the same manner as in the flexible packaging sheet M, except that the printed anchor coat layer was composed of a solution of vinyl chloride-vinyl acetate copolymer having a glass transition temperature of 30°C.

[0066] Comparative Example 12 A flexible packaging sheet P2 was produced in the same manner as the flexible packaging sheet P1, except that the inner anchor coat layer was made of an adhesive made of two-component PU and the sealant layer was made of an LDPE film.

[0067] Comparative Example 13 A flexible packaging sheet Q1 was produced in the same manner as the flexible packaging sheet M, except that the printed anchor coat layer was composed of a solution of vinyl chloride-vinyl acetate copolymer having a glass transition temperature of 70°C.

[0068] Comparative Example 14 A flexible packaging sheet Q2 was produced in the same manner as the flexible packaging sheet Q1, except that the inner anchor coat layer was made of an adhesive made of two-component PU and the sealant layer was made of an LDPE film.

[0069] Comparative Example 15 A flexible packaging sheet R was produced in the same manner as in the flexible packaging sheet A1, except that the printed anchor coat layer was omitted, according to a conventional method.

[0070] The layer structure of the flexible packaging sheet of the example is shown in Table 1, and that of the flexible packaging sheet of the comparative example is shown in Table 2.

[0071] 1. Evaluation of printing defects: Underwater rubbing test The test is carried out as follows.

[0072] (Room temperature water treatment) Three test pieces measuring 10 cm square were cut out from one soft packaging sheet, and one of them was placed in the center of the palm of one hand. At this time, the overprint coat layer was placed on the top side. Then, the palm of the other hand was placed over the test piece, and the test piece was submerged in 24°C water while being held between the hands. Next, the test piece was firmly clenched once in the water as if rolling it up inside the palm of one hand, and after strongly deforming it, the fist was removed from the water. Next, the fingers were opened, and the wet test piece A1 was spread out to smooth out the wrinkles. Then, the presence or absence of peeling of the printed ink layer was visually observed mainly in the wrinkled areas. The above evaluation was also performed on the remaining two test pieces. The evaluation in this test was performed according to the following criteria.

[0073] ○: Ratio of (number of test pieces where the printed ink layer did not peel off / number of test pieces immersed) = 3 / 3 ×: Ratio = 2 / 3, 1 / 3 or 0 / 3

[0074] (High temperature water treatment) Three test pieces measuring 10 cm square were cut out from one soft packaging sheet, one of which was immersed in 80°C hot water for three days, then removed to room temperature and the water adhering to the surface was lightly wiped off with a nonwoven fabric. The same procedure as for the room temperature water treatment was then carried out on the same test piece, and the presence or absence of peeling of the printed ink layer was visually observed, mainly in the wrinkled areas. The same evaluation was carried out on the other two test pieces. Evaluation in this test was carried out according to the following criteria.

[0075] ◎: Ratio of (number of test pieces where the printed ink layer did not peel off / number of test pieces immersed) = 3 / 3 ○: Same ratio = 2 / 3 ×: Ratio = 1 / 3 or 0 / 3

[0076] The high-temperature water treatment is a forced operation for promoting the penetration of water into the inside of the test piece.

[0077] 2. Evaluation of printing defects: Friction test This test was carried out using a sliding test apparatus, the schematic of which is shown in Figure 4. (4) This is done using this device. (4) Stainless steel support (41) and a stainless steel spherical member connected to the tip. (42) (diameter 10mm) and a stainless steel support (43) The spherical member is at least (42) is covered with cotton gauze (not shown).

[0078] In this test, first, two test pieces measuring 10 cm square are prepared from one soft packaging sheet. Then, one of the test pieces is placed on the support stand. (43) Then, 0.5 cc of water was dropped onto the surface of the overprint coat layer, and the spherical member was placed on the (42) , pillar (41) In this state, the support is pressed lightly by lowering the (41) The paper is moved back and forth at a distance of 2 cm / sec from side to side, and the number of times it is moved back and forth is counted until the appearance of the printed surface changes, such as scratches, occurs. The upper limit is 30 times. The print defect prevention against frictional force is evaluated according to the following criteria.

[0079] ◯: No change in appearance occurs on the printed surface even after 28 or more reciprocations. △: Appearance changes after 25 to 27 reciprocations. ×: Appearance changes occur after 24 or fewer reciprocations.

[0080] 3.Deadhold test This test is carried out as follows. First, a 10 cm square test piece is prepared from one soft packaging sheet, arranged side by side on a support stand, and the four sides are fixed with adhesive tape. Then, a stainless steel plate (760 g) adjusted to 24°C is placed over the test piece and left for one minute. Next, the plate is removed, and the degree to which each folded sample returns to its original shape is visually observed for one minute. Then, the dead hold property is evaluated according to the following criteria.

[0081] ○: The folded sample does not open at all. ×: The folded sample opens even slightly.

[0082] The evaluation results of Tests 1 to 3 are shown in Table 1 for the flexible packaging material sheets of the Examples, and in Table 2 for the Comparative Examples.

[0083] [Table 1]

[0084] [Table 2] [Industrial Applicability]

[0085] The flexible packaging sheet of the present invention can be used as a bag-shaped container for storing foods such as cream cheese, jelly, and yokan, industrial products such as glue, sealant, and clay, and other contents such as medicines and chemicals. [Explanation of symbols]

[0086] (1) Flexible packaging sheet: (10) overprint coat layer, (11) printed ink layer, (12) printed anchor coat layer, (13) barrier layer, (14) adhesive layer, (15) reinforcing layer, (16) inner anchor coat layer, (17) sealant layer (2) Bag-shaped container: (21) opening, (22) opening edge, (23) body, (24) linear seal, (25) bottom (3) Packaging body: (26) Opening section (C)Contents

Claims

1. A soft packaging sheet used for producing a package in which contents are stored in a bag-like container and which is to be stored in a refrigerator, comprising: The soft packaging sheet is, in order from the outside, an overprint coat layer forming the outermost layer; A printing ink layer; A printed anchor coat layer; A barrier layer made of a metal foil; a sealant layer made of a heat-fusible resin; At least one of the following is provided: The present invention is characterized in that the anchor coating agent constituting the printed anchor coating layer is a one-component curing type agent containing a saturated copolymer polyester resin having a glass transition temperature of -30°C to 60°C, and the overcoat agent constituting the overprint coating layer is a cellulose-based overcoat agent. Soft packaging sheet.

2. 2. The flexible packaging material sheet according to claim 1, further comprising a reinforcing layer made of a synthetic resin film disposed between said barrier layer and said sealant layer.

3. 3. A sealed package, which is produced by putting contents into a bag-like container made of the soft packaging material sheet according to claim 1 or 2, and then heat-sealing the opening edge of the bag-like container, and which is stored in a refrigerator.

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