Laminated sheets for lids, lids, food packaging containers, and packaged foods

Abstract

To provide a laminate sheet for a lid body made of paper having excellent oxygen barrier properties as a lid body for a chilled food packaging container, a lid body composed of the laminate sheet for a lid body, a food packaging container equipped therewith, and a packaged food with a food packaged in the food packaging container.SOLUTION: A laminate sheet 10 for a lid body is to be used for a lid body of a food packaging container including a container body with an opening and a lid body covering the opening. The laminate sheet for a lid body includes a heat seal layer 1, a first functional layer 2 having gas barrier properties, a paper substrate 3, a printed layer 4 and a second functional layer 5 having water proofness in this order. The mass of the paper substrate 3 is 50% or more of the mass of the laminate sheet 10 for a lid body.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to laminated sheets for lids, lids, food packaging containers, and packaged food products. [Background technology]

[0002] In recent years, demand for prepared or processed chilled foods sold in convenience stores and supermarkets has been growing, supported by changes in household structure due to the rise of nuclear families, changes in lifestyles, and advances in distribution and freezing / refrigeration technologies. Simultaneously, demand for packaging containers to hold chilled foods is also increasing.

[0003] Meanwhile, with efforts underway to reduce plastic waste, there is a growing demand for food packaging containers made from paper, a renewable resource with a low environmental impact. Paper packaging containers, using paper as the base material, are also being increasingly required for packaging chilled foods.

[0004] In food packaging containers, excellent oxygen barrier properties are crucial to prevent the intrusion of oxygen from the outside, thereby suppressing the oxidation of the food being filled. Oxygen barrier properties are also required for the lid, which is one of the components of food packaging containers. To impart gas barrier properties against oxygen and other gases to paper-based lids, for example, metal foil or metal-deposited film made of metal such as aluminum is often used as a gas barrier layer on the paper base material. However, lids containing aluminum foil or aluminum-deposited film have several problems: they cannot be inspected for the presence of metal foreign objects using metal detectors after the contents are filled on the product manufacturing line; they cannot be incinerated as paper because they contain metal and cannot be recycled as waste paper; and they cannot be used as packaging containers for chilled foods that are expected to be heated in a microwave oven.

[0005] On the other hand, in aluminum-free lids that do not use aluminum foil or aluminum vapor-deposited film, resins such as polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinylidene chloride, and polyacrylonitrile are often used as the gas barrier layer laminated on the paper substrate. For example, Patent Document 1 discloses a food packaging material comprising two gas barrier layers made of ethylene-modified polyvinyl alcohol resin laminated on a paper substrate. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2009-184138 [Overview of the project] [Problems that the invention aims to solve]

[0007] Chilled foods are foods that are distributed and stored at temperatures ranging from 0 to 10°C, although the optimal temperature range is set for each type of food. Packaged products containing chilled foods in chilled food packaging containers reach consumers through various distribution channels after manufacturing. During this process, for example, the packaged products are kept at room temperature from the time the consumer purchases them at a store until they store them in their refrigerator at home, and from the time the consumer takes the packaged products out of the refrigerator until they cook them.

[0008] The inventors have found that when using a paper lid for chilled food packaging containers, in which a gas barrier layer is formed on the container body side of the paper substrate, the gas barrier performance of the lid, particularly the oxygen barrier performance, decreases rapidly during the first few hours after exposure from a refrigerated state to a room temperature environment. This tendency is especially noticeable when the mass of the paper substrate accounts for 50% or more of the mass of the lid.

[0009] The present invention was developed in view of the above-mentioned problems, and aims to provide a laminated paper sheet for lids that has excellent oxygen barrier properties as a lid for chilled food packaging containers. The present invention also aims to provide a lid made of the above-mentioned laminated sheet for lids, and a food packaging container equipped with the lid. Furthermore, the present invention aims to provide packaged food in which food is contained in the above-mentioned food packaging container. [Means for solving the problem]

[0010] According to a first aspect of the present invention, a laminated sheet for a lid is provided for use on the lid of a food packaging container comprising a container body having an opening and a lid covering the opening, wherein the laminated sheet for a lid includes, in this order, a heat-seal layer, a first functional layer having gas barrier properties, a paper substrate, a printed layer, and a second functional layer having water resistance, and the mass of the paper substrate is 50% or more of the mass of the laminated sheet for the lid.

[0011] Furthermore, according to a second aspect of the present invention, a lid made of the above-mentioned laminated sheet for lids is provided.

[0012] Furthermore, according to a third aspect of the present invention, a food packaging container is provided, comprising a container body having an opening and a lid covering the opening, wherein the first functional layer is disposed between the paper substrate and the internal space of the food packaging container, and the second functional layer is disposed between the paper substrate and the external space of the food packaging container.

[0013] Furthermore, according to a fourth aspect of the present invention, a packaged food is provided in which food is contained in the above-mentioned food packaging container. [Effects of the Invention]

[0014] According to the present invention, there is provided a laminated sheet for a lid, which is made of paper and has excellent oxygen barrier properties as a lid for a chilled food packaging container. Further, according to the present invention, there are provided a lid made of the laminated sheet for a lid, and a food packaging container including the same. Further, according to the present invention, there is provided a packaged food in which food is contained in the food packaging container.

Brief Description of the Drawings

[0015] [Figure 1] A partial cross-sectional view schematically showing an example of a laminated sheet for a lid according to the first embodiment of the present invention. [Figure 2] A partial cross-sectional view schematically showing another example of the laminated sheet for a lid according to the first embodiment of the present invention. [Figure 3] A partial cross-sectional view schematically showing another example of the laminated sheet for a lid according to the first embodiment of the present invention. [Figure 4] A cross-sectional view schematically showing an example of a food packaging container according to the third embodiment of the present invention, which includes a lid according to the second embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments described below are more specific embodiments of any of the above aspects. For elements having the same or similar functions, the same reference numerals are given, and redundant descriptions are omitted.

[0017] [First Embodiment] As described above, when using a lid in which a gas barrier layer is formed on the surface of a paper substrate on the side of the packaging container body as a paper lid for a chilled food packaging container, there is a problem that the oxygen barrier property of the lid rapidly decreases during the first few hours after exposure from a refrigerated environment to a normal temperature environment.

[0018] The inventors have determined that the above problem is caused by condensation occurring on the lid surface and the use of paper as the base material. Specifically, when packaged items that have been in a refrigerated environment are exposed to room temperature, condensation occurs on the outer surface of the lid, and this moisture reaches the gas barrier layer from the paper base material, damaging the gas barrier layer. As a result, the oxygen barrier performance of the paper lid deteriorates.

[0019] Therefore, the first embodiment of the present invention provides a laminated sheet for lids, characterized in that, in order to suppress the deterioration of oxygen barrier performance due to condensation, it has a structure in which a first functional layer having gas barrier properties (hereinafter also referred to as the "gas barrier layer") and a second functional layer having water resistance (hereinafter also referred to as the "water-resistant layer") are laminated with a paper substrate in between. When this laminated sheet for lids is used as a lid for a food packaging container, it is heat-sealed to the container body such that the gas barrier layer is located between the paper substrate and the internal space of the container (hereinafter also referred to as the "lower side of the paper substrate"), and the water-resistant layer is located between the paper substrate and the external space of the container (hereinafter also referred to as the "upper side of the paper substrate"). As a result, moisture due to condensation on the lid surface is prevented from reaching the gas barrier layer, thereby reducing damage to the gas barrier layer and suppressing the deterioration of oxygen barrier performance in the lid.

[0020] Figure 1 is a schematic cross-sectional view showing an example of a laminated sheet for a lid according to the first embodiment of the present invention. The laminated sheet for a lid 10 shown in Figure 1 includes, in this order, a heat seal layer 1, a first functional layer (gas barrier layer) 2 having gas barrier properties, a paper substrate 3, a printed layer 4, and a second functional layer (water-resistant layer) 5 having water resistance.

[0021] As described above, the laminated sheet for the lid according to this embodiment reduces damage to the gas barrier layer and suppresses a decrease in oxygen barrier performance by preventing moisture generated on the lid surface due to condensation from reaching the gas barrier layer located beneath the paper substrate. Therefore, in the laminated sheet for the lid according to this embodiment, the degree of water absorption from the second functional layer side in the laminated sheet from the water-resistant second functional layer to the paper substrate (hereinafter also referred to as the "partially laminated sheet") is controlled by the water-resistant second functional layer.

[0022] Here, water absorption refers to the water absorption rate at a contact time of 300 seconds with water, according to the Cobb method for testing the water absorption rate of paper and cardboard based on JIS P 8140-1998. Furthermore, the partially laminated sheet from the water-resistant second functional layer to the paper substrate refers to the laminated sheet from the water-resistant second functional layer to the paper substrate, as described above. In the lid laminated sheet 10 in Figure 1, it is a partially laminated sheet consisting of the second functional layer 5, the printed layer 4, and the paper substrate 3. In the lid laminated sheet 11 in Figure 2 and the lid laminated sheet 12 in Figure 3, which will be described later, it is a partially laminated sheet consisting of the second functional layer 5, the printed layer 4, the third functional layer 7, and the paper substrate 3.

[0023] In the laminated sheet for the lid according to this embodiment, the water absorption rate from the second functional layer side using the cup method described above is 20 g / m². 2 Preferably, it is 10 g / m 2 More preferably, the following is true: 5 g / m 2 The following is even more preferable: The water absorption rate is preferable as low as possible, and its lower limit is ideally 0 g / m². 2 However, in reality, for example, 1 g / m 2 That's fine too.

[0024] Thus, the laminated sheet for lids according to this embodiment, which has a second functional layer having water resistance on the upper side of the paper substrate and a first functional layer having gas barrier properties on the lower side, is extremely excellent as a lid for chilled food packaging containers because, despite being made of paper, it suppresses the deterioration of oxygen barrier properties due to condensation.

[0025] Each layer included in the laminated sheet 10 for the lid body will be described below. (Paper base material) The laminated sheet 10 for the lid body includes a paper base material 3 as a base. In the present embodiment, the mass of the paper base material 3 in the laminated sheet 10 for the lid body is 50% or more of the total mass of the laminated sheet 10 for the lid body. In one form, the mass of the paper base material 3 in the laminated sheet 10 for the lid body may be 50% or more and 90.9% or less, and may be 51% or more and 80% or less.

[0026] The paper base material 3 is not particularly limited as long as it is mainly composed of plant-derived pulp. Examples of the type of the paper base material include fine paper, medium paper, lightly coated paper, coated paper, single-sided coated paper, bleached or unbleached kraft paper (acidic paper or neutral paper), etc. The basis weight of the paper base material 3 is, for example, 20 g / m 2 ~500 g / m 2 and may be 30 g / m 2 ~100 g / m 2 and may be. If the basis weight of the paper base material 3 is too large, the lid body becomes hard and the opening property deteriorates, while if the basis weight is too small, the strength of the lid body is insufficient. Also, the thickness of the paper base material 3 can be configured, for example, to be the thickness corresponding to the above basis weight.

[0027] (First functional layer having gas barrier property) The first functional layer (gas barrier layer) 2 having gas barrier property is a layer having gas barrier property that can suppress the intrusion of gases such as oxygen, water vapor, and aroma components from the outside. The first functional layer (gas barrier layer) 2 is, in one form, a single-layer or laminated film having an oxygen permeability of 0.1~100 cc / m 2 / day / atm in an atmosphere of 30°C and 70% relative humidity. Further, it may be a gas barrier layer formed by coating.

[0028] Examples of single-layer films include ethylene-vinyl alcohol copolymer films, nylon films, PET (polyethylene terephthalate) films, PAN (polyacrylonitrile) films, PBT (polybutylene terephthalate) films, and PMP (polymethylpentene) films. Examples of laminated films include those made by coating various plastic films with polyvinyl alcohol resin, and those made by vapor-depositing inorganic oxides.

[0029] Inorganic oxides that can be used include metal oxides such as silicon oxide, aluminum oxide, magnesium oxide, calcium oxide, potassium oxide, tin oxide, sodium oxide, boron oxide, titanium oxide, lead oxide, zirconium oxide, and yttrium oxide.

[0030] The gas barrier layer formed by coating can be created by applying resins such as polyvinyl alcohol, ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, polyvinylidene chloride, polyacrylonitrile, or epoxy resin as a coating solution. Furthermore, organic and inorganic fine particles, layered inorganic materials, and curing agents may be added to this coating solution.

[0031] The thickness of the first functional layer 2 having gas barrier properties may be, for example, 0.1 μm or more and 30 μm or less, or 1 μm or more and 12 μm or less.

[0032] (Printing layer) The printed layer 4 is a layer formed for practical use as a product. The printed layer 4 is composed of ink, which is made by adding various pigments, extender pigments, plasticizers, drying agents, stabilizers, etc. to conventionally used ink binder resins such as urethane, acrylic, nitrocellulose, rubber, and vinyl chloride, and forms characters, images, etc., on it. As for the formation method, well-known printing methods such as offset printing, gravure printing, and silkscreen printing, or well-known coating methods such as roll coating, knife-edge coating, and gravure coating can be used.

[0033] The thickness of the printed layer 4 is not particularly limited and may be, for example, 0.1 μm to 5 μm, or 0.2 μm to 1 μm.

[0034] (A second functional layer with water resistance) The water-resistant second functional layer (water-resistant layer) 5 is a water-resistant layer that can suppress moisture from condensation and the like from passing through the paper substrate from the outside and reaching the gas barrier layer. In one embodiment, the second functional layer 5 is formed on the printed layer 4, thereby controlling the water absorption of the partially laminated sheet from the second functional layer 5 to the paper substrate 3, and setting the water absorption of the laminated sheet for the lid by the Cobb method described above to 20 g / m². 2 Any layer with sufficient water resistance to meet the following requirements will suffice.

[0035] In one embodiment, the second functional layer 5, which has water resistance, is preferably an overprint varnish layer (hereinafter referred to as the "OP varnish layer").

[0036] The water-resistant second functional layer 5, in one embodiment, contains a water-resistant resin. The water-resistant resin can be any resin capable of providing water resistance that satisfies the water absorption value of the laminated sheet for the lid described above, and is not limited to this. For example, as the water-resistant resin, polyethylene, polypropylene, and their derivatives such as polyolefins (polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, vinyl chloride-vinyl acetate copolymer, etc.), silicones, acrylics, epoxys, polyesters, celluloses, urethanes, etc., can be used. The water-resistant second functional layer can be obtained by coating or laminating a coating containing the water-resistant resin onto the paper substrate 3 on which the printed layer 4 is formed, using a known method. In addition to the water-resistant resin, the coating may also contain pigments, dyes, curing agents, leveling agents, solvents, etc.

[0037] The second functional layer 5 preferably has sufficient abrasion resistance and scratch resistance in order to impart sufficient water resistance to the laminated sheet for the lid, preventing moisture from condensation or the like from passing through the paper substrate from the outside and reaching the first functional layer 2, which has gas barrier properties. From this viewpoint, it is preferable that the amount and thickness of the second functional layer 5 are greater than the amount and thickness of the normal OP varnish layer laminated as a surface protective layer for the printed layer. For example, in the laminated sheet for the lid 10 shown in Figure 1, the amount of the second functional layer 5 is 0.5 g / m². 2 Preferably, it should be 2.0 g / m 2 It is more preferable that the above is true. The upper limit of the amount of the second functional layer 5 applied is, for example, 10 g / m². 2 The following may apply. Furthermore, in the laminated sheet 10 for the lid shown in Figure 1, the film thickness of the second functional layer 5 is preferably 0.5 μm or more, and more preferably 2.0 μm or more. The upper limit of the film thickness of the second functional layer 5 may be, for example, 10 μm or less.

[0038] (Heat seal layer) The heat seal layer 1 can be any material capable of heat-sealing the container body 22 and lid 21 of the food packaging container 20 shown in Figure 4 (described later) to seal the container. Generally, films of ethylene-vinyl acetate (EVA), ionomer resin, or other polyolefins are used. Linear low-density polyethylene (LLDPE) and very low-density polyethylene (VLDPE) are preferably used. A known sealant layer with easy-peel functionality can also be used. Furthermore, it can also be formed by applying a heat seal varnish.

[0039] The thickness of the heat seal layer 1 is not particularly limited and may be, for example, 0.5 μm to 60 μm, or 1 μm to 30 μm.

[0040] Figure 2 is a schematic cross-sectional view showing another example of a laminated sheet for a lid according to the first embodiment. The laminated sheet for a lid 11 shown in Figure 2 includes, in this order, a heat seal layer 1, a first functional layer 2 having gas barrier properties, a paper substrate 3, a third functional layer 7, a printed layer 4, and a second functional layer 5 having water resistance. The laminated sheet for a lid 11 has a structure that further includes a third functional layer 7 between the paper substrate 3 and the printed layer 4 compared to the laminated sheet for a lid 10 shown in Figure 1.

[0041] (Third functional layer that provides smoothness) In the laminated sheet 11 for the lid, the surface of the paper substrate 3 is smoothed by interposing a third functional layer 7 between the paper substrate 3 and the printed layer 4. By providing the third functional layer 7 on the paper substrate 3 and smoothing its surface, the second functional layer 5 is formed as a smoothed, uniform film with water resistance, thereby suppressing the reach of moisture to the first functional layer 2 and improving the oxygen barrier performance of the laminated sheet 11 for the lid. The thickness of the third functional layer 7 is not particularly limited and may be, for example, 0.5 μm to 50 μm or 1 μm to 10 μm.

[0042] The third functional layer 7 contains a resin. Examples of resins included in the third functional layer 7 include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, ethylene-α-olefin copolymer polymerized using a metallocene catalyst (single-site catalyst), polypropylene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-propylene copolymer, methylpentene polymer, acid-modified polyolefin resins obtained by modifying polyolefin resins such as polyethylene or polypropylene with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic anhydride, and fumaric acid, thermoplastic resins such as polyethylene terephthalate resin, polybutylene terephthalate resin, and nylon resin. These resins may be used in appropriate combinations. The third functional layer 7 may also contain clay, kaolin, calcium carbonate, talc, mica, etc. as fillers. The third functional layer 7 can be formed by dissolving or dispersing these resins in a solvent to form a coating solution, and then coating it onto the paper substrate 3 using known coating techniques such as gravure printing, offset printing, flexographic printing, screen printing, and inkjet printing.

[0043] As described above, the oxygen barrier properties are improved by the inclusion of the third functional layer 7 in the laminated lid sheet 11. Therefore, the preferred lower limits for the coating amount and film thickness of the water-resistant second functional layer 5 can be smaller than those for the laminated lid sheet 10 shown in Figure 1. For example, in the laminated lid sheet 11 shown in Figure 2, the coating amount of the second functional layer 5 is 0.2 g / m². 2 Preferably, it should be 1.0 g / m 2 It is more preferable that the above conditions are met. Furthermore, in the laminated sheet 11 for the lid shown in Figure 2, the film thickness of the second functional layer 5 is preferably 0.2 μm or more, and more preferably 1.0 μm or more.

[0044] Figure 3 is a schematic cross-sectional view showing another example of a laminated sheet for a lid according to the first embodiment. The laminated sheet for a lid 12 shown in Figure 3 includes, in this order, a heat seal layer 1, a first adhesive layer 6, a first functional layer 2 having gas barrier properties, a paper substrate 3, a third functional layer 7, a printed layer 4, and a second functional layer 5 having water resistance. The laminated sheet for a lid 11 is the same as the laminated sheet for a lid 11 shown in Figure 2, except that it includes a first adhesive layer 6 between the sealant layer 1 and the first functional layer 2 having gas barrier properties.

[0045] (First adhesive layer) The laminated sheet 12 for the lid includes a first adhesive layer 6 that bonds the sealant layer 1 and the first functional layer 2. As the first adhesive layer 6, an adhesive resin or adhesive can be appropriately selected and used depending on the materials of the sealant layer 1 and the first functional layer 2 to obtain the required adhesive strength.

[0046] As adhesive resins, one or more resins selected from polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, and copolymers with ethylene-α-olefin polymerized using metallocene catalysts, as well as ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-ethyl acrylate copolymers, ethylene-methacrylic acid copolymers, ethylene-methyl methacrylate copolymers, ethylene-maleic acid copolymers, and ionomer resins can be used in combination.

[0047] The adhesive is produced from an adhesive composition prepared by mixing a first composition containing a main component and a solvent with a second composition containing a curing agent and a solvent. Specifically, the adhesive layer containing the adhesive includes a cured product produced by the reaction of the main component and the curing agent in the adhesive composition. Examples of the main component include polyols, examples of the curing agent include isocyanate compounds, and examples of adhesives include ether-based two-component reactive adhesives or ester-based two-component reactive adhesives. Examples of ether-based two-component reactive adhesives include polyether polyurethane. Polyether polyurethane is a cured product produced by the reaction of polyether polyol as the main component and isocyanate compound as the curing agent. Examples of ester-based two-component reactive adhesives include polyester polyurethane and polyester. Polyester polyurethane is a cured product produced by the reaction of polyester polyol as the main component and isocyanate compound as the curing agent. Alternatively, acrylic polyol may be used as the main component.

[0048] (Second adhesive layer) The laminated sheet for the lid according to this embodiment may include a second adhesive layer (not shown) between the paper substrate 3 and the first functional layer 2. As the second adhesive layer, an adhesive resin or adhesive that provides the required adhesive strength can be appropriately selected and used depending on the materials of the paper substrate 3 and the first functional layer 2. Examples of adhesive resins and adhesives that can be used as the second adhesive layer include the vapor-bonding resins and adhesives described for the first adhesive layer.

[0049] [Second Embodiment] The lid according to the second embodiment of the present invention is a lid molded using the laminated sheet for lids according to the first embodiment described above, and an example thereof is the lid 21 schematically shown in Figure 4, which will be described later. In the lid according to this embodiment, moisture due to condensation on the lid surface is prevented from reaching the gas barrier layer, so that the gas barrier layer is not damaged by condensation. For this reason, the lid according to this embodiment can suppress a rapid decrease in oxygen barrier properties during the first few hours after being exposed from a refrigerated environment to a room temperature environment, and can be suitably used as a lid for chilled food packaging containers.

[0050] [Third Embodiment] Figure 4 is a schematic cross-sectional view showing an example of a food packaging container according to a third embodiment of the present invention. The food packaging container 20 shown in Figure 4 comprises a container body 22 having an opening and a lid 21 covering the opening. The container body 22 has a flange 22a on the periphery of the opening, and the lid 21 is sealed to the flange 22a. The lid 21 is a molded body of a laminated sheet for a lid according to the first embodiment, and although not shown, is sealed to the container body 22 via a heat seal layer 1. For this reason, in the food packaging container 20, the first functional layer 2 is arranged between the paper substrate 3 and the internal space of the food packaging container 20, and the second functional layer is arranged between the paper substrate 3 and the external space of the food packaging container 20.

[0051] When sealing the container body 22 and the lid 21, the flange 22a of the container body 22 and the lid 21 are overlapped, and the overlapping area is heat-sealed from the lid 21 side with a sealing bar to ensure a tight seal. The sealing temperature, sealing pressure, and sealing time can be set as appropriate.

[0052] The food packaging container 20 according to the third embodiment is equipped with the lid 21 according to the second embodiment described above, and therefore has excellent oxygen barrier properties when exposed from a refrigerated environment to a room temperature environment, particularly within the first few hours of exposure from a refrigerated environment to a room temperature environment. For this reason, the food packaging container according to this embodiment is suitably used as a packaging container for chilled foods.

[0053] The food packaging container 20 may be filled with an inert gas by gas displacement packaging using a known method before being sealed. By changing the gas composition inside the container, it is possible to suppress bacterial growth and extend the shelf life, maintain the flavor and color of the food for a longer period by preventing oxidation, and prevent the loss of vitamins. As the inert gas, for example, a mixture of oxygen gas, nitrogen gas, and carbon dioxide gas is preferably used, and a gas composition suitable for each food can be selected.

[0054] [Fourth Embodiment] A packaged food according to the fourth embodiment of the present invention is made by containing food in a food packaging container according to the third embodiment described above. The food contained is not particularly limited, but since the food packaging container according to the third embodiment can be suitably used as a chilled food packaging container for the reasons described above, chilled food is preferred, for example, cooked or processed refrigerated food (e.g., grilled fish, boiled fish, prepared foods, etc.). [Examples]

[0055] The present invention will be described in more detail below based on specific examples and comparative examples. <Example 1> Glossy paper (basis weight 65g / m²) as a paper base material (3) 2 A coating film mainly composed of polyvinyl alcohol (coating amount 13g / m²) is applied to the main non-gloss surface of the ) 2 A laminated sheet was prepared, in which a gas barrier layer (2) with a thickness of 10 μm was laminated.

[0056] On the main surface of the paper substrate (3) opposite to the main surface on which the gas barrier layer (2) is formed, printing ink is applied by gravure printing at a rate of 1 g / m². 2 The surface was coated, and the printed layer (4) was laminated. On top of the printed layer (4), an OP varnish agent (product name "MFT8GOP"; manufactured by Toyo Ink Co., Ltd.) mainly composed of nitrocellulose resin was applied by gravure coating, with an application rate of 10 g / m². 2 A water-resistant layer (5) consisting of an OP varnish layer (in a dry state) was laminated.

[0057] Next, an adhesive composition containing a polyester-based main component (product name "Takelac A525"; manufactured by Mitsui Chemicals, Inc.) and an aliphatic isocyanate-based curing agent (product name "Takelac A52"; manufactured by Mitsui Chemicals, Inc.) is applied to the gas barrier layer (2) by gravure coating, with an application amount of 2 g / m². 2 A dry adhesive layer (6) was laminated. On top of the adhesive layer (6), a sealant layer (1) with a thickness of 30 μm and a density of 27 g / m² was applied. 2 A laminated sheet for the lid was obtained by laminating an unstretched film (product name "TUX(registered trademark) MCS #30"; manufactured by Mitsui Chemicals Tohcello Co., Ltd.) whose main component is linear low-density polyethylene (LLDPE).

[0058] <Comparative Example 1> A laminated sheet for the lid was manufactured in the same manner as in Example 1, except that a water-resistant layer (5) consisting of an OP varnish layer was not provided.

[0059] <Evaluation of oxygen barrier properties> (Preparation of test specimens for oxygen permeability measurement) The laminated sheets for the lids obtained in Example 1 and Comparative Example 1 were cut into 4cm x 4cm shapes to serve as test specimens. Two test specimens were prepared for each of Example 1 and Comparative Example 1. The test specimens were sandwiched between two aluminum films, each having a 25mm diameter hole in the center, and fixed with adhesive so that the two holes overlapped. By laminating these films, an aluminum laminate (hereinafter also referred to as the "aluminum laminate") was obtained to hold the laminated sheets for the lids. This aluminum laminate was used as the lid of an aluminum cup in the oxygen permeability measurement test described later.

[0060] The aluminum cups used were those conforming to the aluminum moisture-permeable cups specified in JAPAN TAPPI Paper and Pulp Test Method No. 7:2000 Paper and Cardboard - Moisture Permeability Test Method B. A total of four test specimens for environmental storage, used in the tests described below, were prepared by placing the aluminum laminate containing the test specimens into the opening of these cups, closing the lid, and securing it with fasteners.

[0061] (Environmental storage of test specimens and measurement of oxygen permeability) Each test specimen obtained above was first stored for 12 hours in a refrigerated environment at 5°C and humidity-free. Next, one of the two test specimens in each of Example 1 and Comparative Example 1 was subjected to environmental storage for 1 hour in a high-temperature, high-humidity environment at 40°C and 90% relative humidity, thereby forcibly inducing condensation on the surface of the test specimen located on the outside of the cup. Then, as a static adjustment before measuring oxygen permeability, each test specimen was stored for 24 hours in an environment at 24°C and 55% relative humidity, after which oxygen permeability was measured (Condition 2). Furthermore, for the other test specimen in each of Example 1 and Comparative Example 1, after being stored in the refrigerated environment as described above, the static adjustment was performed without the above-described environmental storage in the high-temperature, high-humidity environment, and then oxygen permeability was measured (Condition 1).

[0062] Oxygen permeability was measured using a MOCON OX-TRAN2 / 20 oxygen permeability analyzer under conditions of 30°C and 70% relative humidity. The results are shown in Table 1. Lower oxygen permeability indicates superior oxygen barrier properties.

[0063] [Table 1]

[0064] As shown in Table 1, the measurements obtained by this embodiment demonstrate that the lid using the laminated sheet for lids controls the deterioration of barrier performance due to condensation even when exposed from a refrigerated environment to a high-temperature, high-humidity environment, and dramatically improves the deterioration of oxygen barrier performance. Considering that the time from when consumers purchase packaged goods containing chilled food at a store until they store them in their refrigerators at home, and the time from when consumers take the packaged goods out of the refrigerator until they cook them, it can be seen that the lid using the laminated sheet for lids according to this embodiment is extremely effective as a lid for chilled food packaging containers.

[0065] It should be noted that the present invention is not limited to the embodiments described above, and can be modified in various ways during implementation without departing from its essence. Furthermore, each embodiment may be combined as appropriate, and in that case, the combined effects can be obtained. Moreover, the above embodiments include various inventions, and various inventions can be extracted by selecting combinations from the multiple constituent elements disclosed. For example, if the problem can be solved and effects obtained even if some constituent elements are deleted from all the constituent elements shown in the embodiment, then the configuration with these deleted constituent elements can be extracted as an invention. [Explanation of Symbols]

[0066] 1. Heat seal layer 2. First Functional Layer 3 Paper base material 4 printing layer 5. Second Functional Layer 6. First adhesive layer 7. Third Functional Layer 10, 11, 12 Laminated sheets for lids 20 Food packaging containers 21 Lid 22 Container body 22a Flange [Note] The invention described in the original claims of this application is listed below. [1] A laminated sheet for a lid used in the lid of a food packaging container comprising a container body having an opening and a lid covering the opening, wherein the laminated sheet for a lid includes, in this order, a heat-seal layer, a first functional layer having gas barrier properties, a paper substrate, a printed layer, and a second functional layer having water resistance, and the mass of the paper substrate is 50% or more of the mass of the laminated sheet for the lid. [2] The second functional layer has an application amount of 0.5 g / m². 2 The above is the laminated sheet for the lid as described in Appendix [1]. [3] The laminated sheet for a lid according to Appendix [1], further comprising a third functional layer that provides smoothness between the paper substrate and the printed layer. [4] The second functional layer has an application amount of 0.2 g / m². 2 The above is the laminated sheet for the lid as described in Appendix [3]. [5] The water absorption of the laminated sheet for the lid from the second functional layer side, where the water absorption after a 300-second contact time with water according to the Cobb method for testing the water absorption of paper and cardboard based on JIS P 8140-1998, is 20 g / m². 2 The laminated sheet for the lid as described in any one of the appendices [1] to [4] below. [6] The laminated sheet for the lid according to any one of the appendices [1] to [5], wherein the food packaging container is a chilled food packaging container. [7] A lid made of a laminated sheet for lids as described in any one of the appendices [1] to [6]. [8] A food packaging container comprising a container body having an opening and a lid as described in Appendix [7] that covers the opening, wherein the first functional layer is disposed between the paper substrate and the internal space of the food packaging container, and the second functional layer is disposed between the paper substrate and the external space of the food packaging container. [9] The food packaging container according to Appendix [8], wherein the container body has a flange on the periphery of the opening, and the lid is heat-sealed to the flange via the heat-seal layer.

[10] The food packaging container according to Appendix [8] or [9], wherein the internal space of the food packaging container is filled with a mixed gas containing oxygen, nitrogen, and carbon dioxide.

[11] A food packaging container for chilled foods, as described in any one of the appendices [8] to

[10] .

[12] Packaged food in which food is contained in a food packaging container as described in any one of the appendices [8] to

[11] .

Claims

1. A laminated sheet for a lid of a chilled food packaging container, comprising a container body having an opening and a lid covering the opening, wherein the laminated sheet for a chilled food packaging container includes, in this order, a heat-seal layer, a first functional layer having gas barrier properties, a paper substrate, a printed layer, and a second functional layer having water resistance, the mass of the paper substrate being 50% or more of the mass of the laminated sheet for the lid, and the water absorption from the second functional layer side of the partial laminated sheet from the second functional layer to the paper substrate, with a water absorption rate of 20 g / m2 or less after a contact time of 300 seconds according to the Cobb method for testing the water absorption of paper and cardboard based on JIS P 8140-1998.

2. The laminated sheet for lids for chilled foods according to claim 1, wherein the amount of the second functional layer applied is 0.5 g / m2 or more.

3. The laminated sheet for chilled food lids according to claim 1, further comprising a third functional layer that provides smoothness between the paper substrate and the printed layer.

4. The laminated sheet for chilled food lids according to claim 3, wherein the amount of the second functional layer applied is 0.2 g / m2 or more.

5. A lid made of a laminated sheet for chilled food lids according to any one of claims 1 to 4.

6. A food packaging container comprising a container body having an opening and a lid according to claim 5 that covers the opening, wherein the first functional layer is disposed between the paper substrate and the internal space of the food packaging container, and the second functional layer is disposed between the paper substrate and the external space of the food packaging container.

7. The chilled food packaging container according to claim 6, wherein the container body has a flange on the periphery of the opening, and the lid is heat-sealed to the flange via the heat-seal layer.

8. The chilled food packaging container according to claim 6 or 7, wherein the internal space of the chilled food packaging container is filled with a mixed gas containing oxygen gas, nitrogen gas, and carbon dioxide gas.

9. A packaged food in which food is contained in a food packaging container according to any one of claims 6 to 8.

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