Packaging material

Abstract

To provide a packaging material which can ensure a good initial seal strength and is excellent in openability and resealability even when a seal area is relatively small.SOLUTION: The packaging material comprises a laminate including a pressure-sensitive adhesive layer and a sealant layer in this order on at least one surface of a substrate layer, wherein (1) the pressure-sensitive adhesive layer has a layering amount of 10 to 50 g / m2 by dry weight and contains an acrylic pressure-sensitive adhesive, and (2) the sealant layer comprises a cyclic olefin copolymer-containing layer and a polyolefin resin-containing layer in this order.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a novel packaging material. [Background technology]

[0002] In recent years, there has been an increasing demand for environmentally friendly packaging materials in order to promote the recycling of plastic resources. Furthermore, marine pollution caused by microplastics and other contaminants has become a major social issue worldwide, and the development of new packaging materials that address the ever-increasing waste problem is being widely pursued. The development of environmentally friendly packaging materials is being promoted primarily with the aim of eliminating plastic, shifting to monomaterials, and promoting recycling.

[0003] One such packaging material is known to have a resealing function (resealability). This means that after the packaging material is opened, the opening can be resealed with fingers or the like. For this reason, when the packaging material is used as a lid or the like for a container, for example, the packaging material must have sufficient sealing strength (initial seal strength), and must also have the ability to be opened relatively easily with fingers (openability) and the ability to be resealed with fingers after opening (resealability).

[0004] Such resealable packaging materials include, for example, container packaging with an overcap (outer lid) or a snap-on lid, but by replacing these with a top seal that seals with a lid material film, it is possible to reduce the weight of plastic.In addition, because it can be easily opened and sealed multiple times, there is no need to use plastic wrap when temporarily storing some of the contents, which reduces the amount of waste generated.

[0005] Such resealable packaging materials are increasingly being used in the food industry, and packaging forms that are excellent in adhesion, ease of opening, and resealability have been proposed (for example, Patent Documents 1 to 4). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-41539 [Patent Document 2] JP 2020-15545 A [Patent Document 3] Japanese Patent Application Publication No. 2019-167131 [Patent Document 4] Japanese Patent Application Laid-Open No. 2024-8560 Summary of the Invention [Problem to be solved by the invention]

[0007] Regarding the sealing area of ​​packaging materials, the flange width is generally narrow, at just a few millimeters, since most of the containers are those with an overcap (outer lid) attached to the outside of the lid material, or containers with snap-on lids.

[0008] In contrast, the technologies disclosed in Patent Documents 1 to 3 have the problem that when these packaging materials are used as lid materials, sufficient adhesion cannot be obtained depending on the flange width of the container, resulting in insufficient resealability. Generally, containers with overcaps or fitting lids have a narrow flange width of only a few millimeters, which can result in insufficient resealability. On the other hand, attempts to widen the flange width may result in incompatibility with containers with overcaps (outer lids) such as those described above, and may require significant capital investment due to design changes to the container shape.

[0009] Furthermore, in Patent Document 4, although a predetermined opening strength can be obtained even if the flange width of the container is relatively narrow, the sealant film is prone to tearing, and there are cases where the sealing strength, which is the standard standard for utensils or container packaging used for milk and dairy products, is insufficient.

[0010] As described above, there is a strong demand for the development of a resealable packaging material that has both good initial seal strength and excellent openability and resealability, even if the sealing area remains small as is, but at present such a material has not yet been developed.

[0011] Therefore, a main object of the present invention is to provide a packaging material that can ensure good initial seal strength even when the seal area is relatively small, and that is also easy to open and reseal. [Means for solving the problem]

[0012] The present inventors have conducted extensive research in light of the problems of the prior art and have found that a laminate having a specific layer structure can achieve the above object, thereby completing the present invention.

[0013] That is, the present invention relates to the following packaging material. 1. A laminate comprising a pressure-sensitive adhesive layer and a sealant layer in this order on at least one surface of a base layer, (1) The adhesive layer has a dry weight of 10 to 50 g / m 2 and containing an acrylic adhesive, (2) The sealant layer includes a cyclic olefin copolymer-containing layer and a polyolefin resin-containing layer in this order from the side closest to the pressure-sensitive adhesive layer. A packaging material characterized by: 2. The packaging material according to item 1, wherein the sealant layer has a thickness of 20 to 60 μm. 3. The lid material according to item 1, wherein the sealant layer further contains a polyolefin resin (excluding cyclic olefin copolymers). 4. The lid material according to item 1, wherein the cyclic olefin copolymer is a copolymer of norbornene and ethylene, and the polyolefin resin contains a polyethylene resin. 5. The covering material according to item 1, wherein the substrate layer is made of at least one material selected from the group consisting of plastics, rubber, metal, glass, ceramics, and paper. 6. A lid material comprising the packaging material according to any one of items 1 to 5. 7. The lid material according to item 6, which is used to heat-seal the sealant layer to a flange formed at the opening of a container. 8. A sealed product in which a flange portion formed at the opening of a container containing contents and the sealant layer of the lid material described in item 6 above are heat-sealed. [Effects of the Invention]

[0014] According to the present invention, even when the sealing area is relatively small, it is possible to provide a packaging material that can ensure good initial sealing strength and is also excellent in openability and resealability.

[0015] In particular, the packaging material of the present invention has a specific layer structure including the sealant layer as described above, and therefore can be suitably used as a lid material for containers. In particular, even when the flange width of the flange at the opening of the container is narrow, a higher initial seal strength (heat seal strength) can be ensured and excellent openability and resealability can be obtained compared to packaging materials of the prior art. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic diagram showing an example of a layer structure of a packaging material of the present invention. [Figure 2] FIG. 1 is a diagram showing an embodiment in which the packaging material of the present invention is used as a lid material for a container. [Figure 3] 1 is a diagram showing a heat-sealed portion between a flange of a container and a lid material when the packaging material of the present invention is used as a lid material for a container. [Figure 4] 1 is a schematic diagram showing a process for making a bag using the packaging material of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] 1. Packaging material of the present invention The packaging material of the present invention is a laminate comprising a pressure-sensitive adhesive layer and a sealant layer in this order on at least one surface of a base layer, (1) The adhesive layer has a dry weight of 10 to 50 g / m 2 and containing an acrylic adhesive, (2) The sealant layer includes a cyclic olefin copolymer-containing layer and a polyolefin resin-containing layer in this order from the side in contact with the pressure-sensitive adhesive layer. It is characterized by:

[0018] An example of an embodiment of the packaging material of the present invention is shown in Fig. 1. In the packaging material (laminate) 10 of Fig. 1, a pressure-sensitive adhesive layer 12 is formed on and in direct contact with a substrate 11. A sealant layer 13 is laminated on and in direct contact with the pressure-sensitive adhesive layer 12.

[0019] 1, the sealant layer 13 is composed of a laminate including, in order, a cyclic olefin copolymer-containing layer 13a (first resin layer) and a polyolefin resin-containing layer 13b (second resin layer). In the present invention, unless otherwise specified, the term "polyolefin resin" is used to exclude cyclic olefin copolymers.

[0020] In the present invention, the first resin layer is the layer in contact with the pressure-sensitive adhesive layer 12, the second resin layer is the layer exposed to the outside, and each layer may be two or more layers, as long as the first resin layer is in contact with the pressure-sensitive adhesive layer 12 and the second resin layer is the outermost layer exposed to the outside. Furthermore, the first resin layer and the second resin layer may be bonded (fused) in a state of direct contact with each other, or may be laminated via another layer. Therefore, for example, a layer structure such as "first resin layer / third resin layer / second resin layer" in which a separate third resin layer is formed between the first resin layer and the second resin layer is also possible. Another layer structure such as "first resin layer / third resin layer / first resin layer / third resin layer / second resin layer" is also possible.

[0021] The packaging material 10 shown in FIG. 1 has a pressure-sensitive adhesive layer 12 and a sealant layer 13 laminated in this order on one surface of a base layer 11, and is heat-sealed to a container or the like at the sealant layer 13 (side A).

[0022] In another embodiment, the present invention also encompasses a packaging material in which a pressure-sensitive adhesive layer 12 and a sealant layer 13 are laminated in this order on both sides (side A and side B) of a substrate layer. In this case, the layer structure is "sealant layer / pressure-sensitive adhesive layer / substrate layer / pressure-sensitive adhesive layer / sealant layer." By adopting such a structure, more complex packaging bags and the like can be produced relatively easily. In this case, too, the second resin layer (polyolefin resin-containing layer) of both sealant layers can be the outermost layer.

[0023] The packaging material of the present invention has the above-described laminate as its basic structure, but other layers may be laminated thereon as long as the effects of the present invention are not impaired. Examples include a printed layer, an OP layer (overprint layer), a clear coat layer, etc. Each layer constituting the packaging material will be described below.

[0024] (1) Base material layer The base layer mainly functions as a core material of the packaging material of the present invention. In particular, it imparts stiffness to the packaging material. This layer imparts durability to the packaging material against punctures and the like, and also serves to provide strength to the packaging material so that the packaging material will not be accidentally torn when peeled off from a container or the like.

[0025] Furthermore, when it is undesirable for the contents filled in a container or the like to be exposed to light, air, etc., the base layer can be given the effect of suppressing light transmission, preventing the intrusion of outside air, or imparting the effect of suppressing gas transmission, such as preventing the smell of the contents from leaking out of the container.

[0026] The material of the substrate layer is not particularly limited as long as it has the above-mentioned functions, and various materials such as plastics, rubber, metal, glass, ceramics, paper, etc. can be used. Therefore, materials that can be suitably used for forming the substrate layer include, for example, paper, synthetic paper, resin film, resin film with a vapor deposition layer, synthetic resin plate, aluminum foil or other metal foil, metal plate, woven fabric, nonwoven fabric, leather, synthetic leather, wood, glass plate, etc., alone or as composite materials or laminate materials thereof. Among these, it is preferable to use aluminum foil or resin film with a vapor deposition layer, since they can prevent light or gas transmission while also achieving a predetermined strength.

[0027] The thickness of the base layer is not particularly limited, but in order to effectively exhibit the functions of the base layer as described above, it is usually preferably about 10 to 200 μm, and more preferably 12 to 100 μm.

[0028] (2) Adhesive layer The adhesive layer mainly functions to provide a predetermined adhesiveness when the packaging material of the present invention is heat-sealed (thermally bonded) to a container or the like, and also to provide resealing strength.

[0029] The pressure-sensitive adhesive layer contains an acrylic pressure-sensitive adhesive. The content of the acrylic pressure-sensitive adhesive in the pressure-sensitive adhesive layer can be, for example, about 90 to 100% by weight, but is not limited to this.

[0030] The type of acrylic resin used in the acrylic pressure-sensitive adhesive is not limited, but at least one acrylic resin selected from the group consisting of (meth)acrylate monomers, vinyl esters, hydroxyl group-containing monomers, carboxyl group-containing monomers, amide group-containing monomers, amino group-containing monomers, epoxy group-containing monomers, aromatic ring-containing monomers, and alicyclic hydrocarbon group-containing monomers can be suitably used. In particular, in the present invention, it is preferred to use an acrylic resin that is a polymer of a (meth)acrylate monomer and at least one of a hydroxyl group-containing monomer and a carboxyl group-containing monomer.

[0031] In this specification, unless otherwise specified, acrylate monomers and methacrylate monomers are collectively referred to as "(meth)acrylate monomers."

[0032] The glass transition temperature (Tg) of the acrylic resin is not particularly limited, but in order to increase the adhesive strength of the acrylic pressure-sensitive adhesive, it is preferably about −80° C. to −10° C., and more preferably −70° C. to −30° C. In this case, the acrylic resin may have two or more glass transition temperatures, and in that case, it is preferable that at least one of them is within the above range.

[0033] The properties of the acrylic pressure-sensitive adhesive are not limited, and any type can be used, such as a solvent-based, solventless, or aqueous type. In the present invention, commercially available acrylic pressure-sensitive adhesives can also be used.

[0034] The adhesive layer thickness (dry weight) is usually 10 to 50 g / m 2 In particular, 15 to 45 g / m 2 This allows for a wide range of designs, from weak to strong adhesion, to suit various properties such as adhesive strength, holding power, and tack. Furthermore, when the packaging material of the present invention is used as a lid material and thermally bonded to a container, it is possible to achieve sufficient resealing strength even when the flange width of the container is narrow. 2 If the lamination amount is less than 50g / m, the bag will not be able to be resealed. 2 If it exceeds this limit, the strength may be too high and it may become impossible to open.

[0035] (3) Sealant layer In the present invention, the sealant layer is a layer that comes into contact with a flange or the like of a container and is heated and pressed to firmly bond the packaging material of the present invention to the container, etc. As described above, the sealant layer is arranged in the order of the first resin layer and the second resin layer from the pressure-sensitive adhesive layer side.

[0036] The first resin layer is a cyclic olefin copolymer-containing layer, that is, the first resin layer contains a cyclic olefin copolymer (COC).

[0037] The cyclic olefin copolymer is a copolymer of a cyclic olefin and an α-olefin, and may be a known compound or may be synthesized by a known production method.

[0038] Examples of the cyclic olefin include norbornene, 5-methyl-bicyclo[2.2.1]hept-2-ene, 5-butyl-bicyclo[2.2.1]hept-2-ene, 5-octyl-bicyclo[2.2.1]hept-2-ene, 5,5-dimethyl-bicyclo[2.2.1]hept-2-ene, 5-ethylidene-bicyclo[2.2.1]hept-2-ene, 5-hexyl-bicyclo[2.2.1]hept-2-ene, 5-octadecyl-bicyclo[2.2.1]hept-2-ene, 5-methylidene-bicyclo[2.2.1]hept-2-ene, 5-vinyl-bicyclo[2.2.1]hept-2-ene, and 5-methyl-bicyclo[2.2.1]hept-2-ene.

[0039] Examples of the α-olefin include at least one of ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, and 4,4-dimethyl-1-pentene.

[0040] Specific examples of cyclic olefin copolymers include at least one of ethylene-cyclic olefin copolymer random copolymers, hydrogenated ring-opened cyclic olefin copolymer copolymers, graft-modified ethylene-cyclic olefin copolymer random copolymers, and ring-opened graft-modified cyclic olefin copolymer copolymers. In particular, copolymers of norbornene and ethylene are preferred in the present invention because they can more effectively impart resealability. Such copolymers are represented by the following general formula: These copolymers can be synthesized by copolymerizing norbornene and ethylene in the presence of a metallocene catalyst according to a known production method.

[0041] [ka] (However, R 1 ~R 4 are the same or different and represent a hydrogen atom or a hydrocarbon group; x and y are the same or different and represent the number of repetitions of each monomer unit.

[0042] The ratio of the two in the cyclic olefin copolymer is, for example, about 20 to 50 mol % of the cyclic olefin, but is not limited to this.

[0043] In the present invention, commercially available cyclic olefin copolymers can also be used, such as those under the product name "TOPAS" (manufactured by Polyplastics Co., Ltd.) and "APEL" (manufactured by Mitsui Chemicals, Inc.).

[0044] The content of the cyclic olefin copolymer in the first resin layer is not limited, but is usually about 60 to 100% by mass, and more preferably 70 to 100% by mass, and therefore may be set to, for example, 80 to 95% by mass, or may also be set to, for example, 90 to 100% by mass. Other components may be contained within the range that does not impair the effects of the present invention, such as resin components other than the cyclic olefin copolymer, fillers, colorants, dispersants, anti-blocking agents, slip agents, etc.

[0045] Furthermore, when a resin other than a cyclic olefin copolymer is contained, one or more resins selected from the group consisting of polyethylene-based resins such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-based copolymers such as polypropylene, ethylene-vinyl acetate copolymer resin, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, and ethylene-propylene copolymer; ionomer resins; methylpentene polymers; and polybutene polymers can be used. The inclusion of a resin other than a cyclic olefin copolymer (particularly a polyolefin-based resin such as a polyethylene-based resin) in the cyclic olefin copolymer layer enhances affinity with the polyolefin-based resin layer, thereby more effectively preventing peeling between the layers. The content of these resin components in the first resin layer is approximately 0 to 40% by mass, and can be in the range of 5 to 40% by mass, or can be, for example, 10 to 30% by mass. However, there are no particular limitations as long as the effects of the present invention are not impaired.

[0046] The thickness of the first resin layer can be set appropriately depending on the type of cyclic olefin copolymer used, the total thickness of the sealant layer, etc., but by making it, for example, approximately 1 to 25 μm, and particularly 5 to 20 μm, it is possible to obtain a film that has excellent initial seal strength, resealing strength, resealability, etc., and also has a balanced density, resulting in a film that curls less.

[0047] The second resin layer is a polyolefin-based resin-containing layer, that is, the second resin layer contains a polyolefin-based resin.

[0048] The polyolefin resin is not particularly limited, and at least one of the following can be appropriately selected and used: polyethylene resins such as low-density polyethylene resin, medium-density polyethylene resin, high-density polyethylene resin, and linear low-density polyethylene; ethylene copolymers such as ethylene-vinyl acetate copolymer resin, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, and ethylene-propylene copolymer; polypropylene resin, ionomer resin, polymethylpentene resin, polybutene resin, etc. Among these, at least one of polyethylene resins and ethylene copolymers is preferred, with polyethylene resins being more preferred, and linear low-density polyethylene being the most preferred due to its excellent compatibility with cyclic olefin copolymers.

[0049] The content of the polyolefin resin in the second resin layer is not limited, but is typically about 60 to 100% by mass, and more preferably 70 to 100% by mass. Therefore, it can be 80 to 95% by mass, or even 90 to 100% by mass. Other components may be included within a range that does not impair the effects of the present invention. Examples of other resin components include resin components other than polyolefin resins, fillers, colorants, dispersants, antiblocking agents, slip agents, etc. Examples of resin components other than polyolefin resins include at least one of polyester resins, polyurethane resins, epoxy resins, acrylic resins, and vinyl resins. These resin components may be included in the second resin layer in a range of about 0 to 30% by mass (particularly 5 to 30% by mass). It is preferable that the second resin layer does not contain a cyclic olefin copolymer as a resin component, but a content of about 5% by mass or less is acceptable.

[0050] The thickness of the second resin layer can be appropriately set depending on the type of polyolefin resin used, the total thickness of the sealant layer, etc., but for example, if it is about 5 to 80 μm, a film with less curl can be obtained by achieving a balanced density. In particular, from the standpoints of initial seal strength, resealability, resealability, etc., a thickness of about 5 to 25 μm is preferable, and a thickness of 10 to 20 μm is even more preferable.

[0051] The total thickness of the sealant layer including the first and second resin layers can be set appropriately depending on, for example, the specific use and area of ​​use of the packaging material, but is usually in the range of about 15 to 100 μm, and preferably 20 to 80 μm.

[0052] (4) Other demographics The packaging material of the present invention may have other layers formed therein as long as the effects of the present invention are not impaired. For example, an adhesive layer may be interposed between the layers. Furthermore, a printed layer, an overcoat layer, a clear layer, etc. may be formed on the surface of the substrate layer opposite to the surface on which the pressure-sensitive adhesive layer is provided (i.e., the surface on the side of the packaging material exposed to the outside).

[0053] 2. Method for producing the packaging material of the present invention The packaging material of the present invention can be suitably produced, for example, by a method including the steps of: (1) forming a pressure-sensitive adhesive layer by applying a coating liquid containing an acrylic pressure-sensitive adhesive to a substrate film that will serve as the substrate layer (first step); and (2) laminating a sealant film that includes, in order, a cyclic olefin copolymer-containing layer and a polyolefin resin-containing layer onto the pressure-sensitive adhesive layer (second step).

[0054] 1st process In the first step, a coating liquid containing an acrylic adhesive is applied to a substrate film that will become the substrate layer, thereby forming a pressure-sensitive adhesive layer.

[0055] The coating liquid may contain any acrylic adhesive, and the acrylic adhesives described above can be used. The solvent used in the coating liquid is not limited, and may be either water or an organic solvent. Alternatively, commercially available acrylic adhesives can be used as they are as the coating liquid. The organic solvent is not limited, and examples include various organic solvents such as alcohol-based solvents (ethanol, methanol, isopropyl alcohol (IPA), hexyl alcohol, etc.), ketone-based solvents (acetone, ketone, methyl ethyl ketone (MEK)), hydrocarbon-based solvents (cyclohexane, normal pentane, normal hexane methylcyclohexane (MCH), etc.), aromatic solvents (toluene, etc.), and glycol-based solvents (propylene glycol, hexylene glycol, butyl diglycol, pentamethylene glycol, etc.).

[0056] The coating method is not particularly limited, and for example, gravure coating, spin coating, comma direct coating, comma reverse coating, spray coating, bar coating, knife coating, roll knife coating, die coating, roll coating, etc. can be used.

[0057] After coating, a drying step may be carried out as necessary. That is, when the coating liquid contains water or an organic solvent, it can be dried, for example, in a drying oven to reduce the solid content to only the solid content. The drying temperature can be set within the range of, for example, 30 to 100°C, but is not limited thereto.

[0058] 2nd process In the second step, a sealant film containing a cyclic olefin copolymer-containing layer and a polyolefin resin-containing layer in this order is laminated on the pressure-sensitive adhesive layer.

[0059] The sealant film may be a laminate including a first film that will become a cyclic olefin copolymer-containing layer (first resin layer) and a second film that will become a polyolefin resin-containing layer (second resin layer). The method for producing the laminate is not particularly limited, and known methods such as a) a method of dry laminating each film, c) a method of laminating each film with an adhesive, d) a method of extrusion lamination in which each film is laminated simultaneously with molding, and e) an inflation method can be used.

[0060] In the second step, the pressure-sensitive adhesive layer is bonded to the surface of the first resin layer of the sealant film in contact with the surface of the first resin layer. In this case, the treatment can be carried out under heating, if necessary.

[0061] In this way, a laminate containing the base layer, the pressure-sensitive adhesive layer, the first resin layer, and the second resin layer in this order is obtained, and the laminate can be used as is as the packaging material of the present invention. In addition, if necessary, a step of laminating a printed layer or the like on the surface of the base layer of the laminate can be appropriately carried out.

[0062] 3. Use of the packaging material of the present invention The packaging material of the present invention can be suitably used for packaging or sealing foods, medicines, cosmetics, etc. In particular, it can be suitably used as a packaging material for sealing contents. For example, it can be used as a lid material for containers, and can also be used for packaging bags (bags), etc.

[0063] When used as a lid for a container, as shown in Fig. 2, the flange 20a of the container 20 and the sealant layer (particularly the second resin layer) of the packaging material 10 of the present invention are placed in contact with each other, and heat-sealed to provide a sealed product in which the contents 21 are sealed in the container 20. The heat-sealing conditions are not particularly limited, and may be, for example, 100 to 200°C for about 0.1 to 5 seconds.

[0064] The type of container is not limited as long as it can be heat-sealed, and can be any container manufactured by various molding methods (especially plastic containers and paper containers).The use is also not particularly limited, and can be any of various food packaging containers, beverage containers, etc.

[0065] In particular, the present invention can achieve good initial seal strength as well as good tear strength and resealability even when the container flange 20a is narrow. When the packaging material of the present invention is used as a lid, the heat-sealed portion with the container is essentially the flat surface of the flange. With conventional lids, as the flange width narrows, the area of ​​the heat-sealed portion also decreases, resulting in reduced initial seal strength. Increasing adhesiveness to avoid this reduction can result in excessive tear strength. In contrast, the packaging material of the present invention can reduce or prevent the problems associated with conventional lids, even when the flange width is relatively narrow. More specifically, the flange width suitable for the packaging material of the present invention is typically 4 mm or less, and may even be 3.5 mm or less. In this case, the lower limit is not limited, but can typically be around 3 mm. Of course, the packaging material of the present invention can also be applied when the flange width exceeds 4 mm.

[0066] In addition, when the flange width of a container is not constant, in the present invention, the width of the portion of the flange where the flange width is smallest is defined as the flange width. For example, when the flange width W is constant as shown in FIG. 3A, the flange width is defined as the width W. On the other hand, when the flange width is not constant as shown in FIG. 3B, the flange width is defined as the narrowest portion Wmin of the flange width. Even when the flange width is mostly wide, if there is a region where the flange width is narrow, there is a risk that the desired initial seal strength, resealability, etc. cannot be obtained locally in that region. For this reason, when the flange width is not constant, it is desirable to define the flange width as Wmin.

[0067] Furthermore, when the packaging material of the present invention is used as a packaging bag, its form is not limited, and it may be, for example, a two-sided bag, a three-sided bag, a two-sided bag, a two-sided bag, a two-sided bag, a two-sided bag, a two-sided bag, a two-sided bag, a two-sided bag, a two-sided bag, a two-sided bag, a two-sided bag, a two-sided bag, a two-sided bag, and a two-sided bag can be produced by heat-sealing the three sides of the material while the two sides are in contact with each other. A schematic cross-sectional view is shown in Figure 4. Of the three sides, the side opposite the fold forms the opening, and this opening can be sealed by heat-sealing the heat-sealed part. In this case, since the heat-sealed part has resealing properties, it can be opened to remove the contents and then closed with fingers. This allows the heat-sealed part to be re-adhered with an appropriate adhesive strength.

[0068] Such packaging materials can be particularly suitably used for packaging products from which the contents can be taken out separately (for example, confectioneries (yogurt, pudding, jelly, snacks, etc.), beverages, seasonings (wasabi paste, pepper, shichimi pepper, etc.), dried foods (Japanese tea, black tea, coffee, cocoa, pasta, hijiki seaweed, wakame seaweed, bonito flakes, etc.), and other products such as instant noodles and instant rice). [Example]

[0069] The features of the present invention will be described in more detail below with reference to examples and comparative examples, but the scope of the present invention is not limited to these examples.

[0070] [Example 1] The base material has a basis weight of 55.0 g / m 2 Polyurethane dry laminating adhesive (weight after drying: 3.5 g / m) 2 (hereinafter also abbreviated as "D")) was used to bond the aluminum vapor deposition surface of a 12 μm thick aluminum vapor deposition polyethylene terephthalate film (hereinafter also abbreviated as "VM-PET") to create a three-layer laminate of "paper (base layer) / D / VM-PET (first adherend layer)". Next, an acrylic adhesive (manufactured by Toyochem Co., Ltd., glass transition temperature: -45°C) was applied as an adhesive to the VM-PET surface (PET layer) of the laminate in an amount of 30 g / m after drying. 2 Onto the coated surface, a 30 μm thick sealant film consisting of a cyclic olefin copolymer-containing layer ("TOPAS (registered trademark)" manufactured by Polyplastics Co., Ltd., COC resin, thickness 10 μm) and a polyolefin resin-containing layer ("Novatec LL" manufactured by Japan Polyethylene Corporation, linear low-density polyethylene, thickness 20 μm) was laminated. The sealant film used was one produced by the inflation method. In this way, a laminate was obtained in the order of "paper (substrate layer) / D / VM-PET / adhesive layer / sealant film".

[0071] [Example 2] A laminate was produced in the same manner as in Example 1, except that the adhesive of the laminate in Example 1 was replaced with an acrylic adhesive manufactured by Nippon Carbide Corporation.

[0072] [Example 3] The coating amount of the adhesive on the laminate of Example 1 was 20 g / m after drying. 2 A laminate was produced in the same manner as in Example 1, except for the above change.

[0073] [Example 4] The coating amount of the adhesive on the laminate of Example 1 was 40 g / m after drying. 2 A laminate was produced in the same manner as in Example 1, except for the above change.

[0074] [Example 5] A laminate was produced in the same manner as in Example 1, except that the olefin resin in the sealant film of the laminate in Example 1 was changed to a sealant film made of low-density polyethylene resin ("Novatec LD", thickness 20 μm).

[0075] [Comparative Example 1] A laminate was produced in the same manner as in Example 1, except that the sealant film of the laminate in Example 1 was changed to a straight-chain (linear) low-density polyethylene film.

[0076] Comparative Example 2 A laminate was produced in the same manner as in Example 1, except that the sealant film of the laminate in Example 1 was changed to a low-density polyethylene film.

[0077] Comparative Example 3 A laminate was produced in the same manner as in Example 1, except that the sealant film of the laminate in Example 1 was changed to a high-density polyethylene film.

[0078] Comparative Example 4 A laminate was produced in the same manner as in Example 1, except that the sealant film of the laminate in Example 1 was changed to a non-stretched co-extruded multilayer film (polyethylene / modified polyethylene layer structure).

[0079] Comparative Example 5 A laminate was produced in the same manner as in Example 1, except that the adhesive in the laminate of Example 1 was changed to a rubber-based adhesive manufactured by Leader Corporation.

[0080] [Test Example 1] The laminates obtained in each example and comparative example were placed on a low-density polyethylene (LDPE) film with a thickness of 80 μm, which was used as a packaging container, at a temperature of 150°C and a pressure of 1 kg / cm. 2 The pieces were heat-sealed at 100°C for 1 second and then bonded together. This resulted in a packaging sample of "paper (base layer) / D / VM-PET / adhesive layer / sealant film / LDPE film." For each of the resulting packaging samples, the adhesive strength between the lid material and the LDPE film used as the packaging container was measured. The results are shown in Table 1. More specifically, each package sample was shredded to a width of 3 mm, and the lid substrate was placed on the upper side of a tensile tester, with the container sheet placed on the lower side. The initial seal strength was measured at a 180° peeling speed of 200 mm / min. The peeled lid substrate and container sheet were then re-attached and pressed together twice with a finger. The tensile tester was then used again to measure the resealability by peeling at a 180° peeling speed of 200 mm / min. This procedure was repeated five times to measure the resealability. The initial seal strength was rated as follows: 2.0N / 3mm or more and 3.0N / 3mm or less: "◎", 1.0N / 3mm or more and less than 2.0N / 3mm: "〇", 0.5N / 3mm or more and less than 1.0N / 3mm: "△", and less than 0.5N / 3mm: "×". The resealing strength was evaluated as follows: a value of 0.2N / 3mm or more was maintained for five times, a value of "◎", a value of less than 0.2N / 3mm for one to two times, a value of "△", a value of less than 0.2N / 3mm for three to five times, and an unmeasurable value (below the peel strength measurement limit of the measuring device, considered to be 0N / 3mm) was evaluated as "×".

[0081] [Test Example 2] The laminates obtained in each example and comparative example were heat-sealed to polyethylene-coated paper containers (flange width 3 mm) as packaging containers under conditions of 150°C, 0.4 MPa, and a sealing time of 1 second. This resulted in a package sample of "base layer / D / VM-PET / adhesive layer / sealant film / paper container." The initial opening strength and resealability of the lid material and paper container were evaluated for each of the resulting package samples. The results are shown in Table 1. For the initial opening strength test, the tab of the lid material on each package was pulled at a speed of 100 m / min in a direction at an angle of 45 degrees from the starting point of opening, and the maximum load at the time of opening was taken as the seal strength (N), and measurements were taken for each package. To test the resealability, the base material of the peeled lid material was re-placed on the flange of the container, and the material was pressed back and forth with a finger twice, after which it was pulled again in a 45-degree direction at a speed of 100 m / min. The maximum load at the time of opening was taken as the seal strength (N), and the resealability of each package was measured. The initial opening strength was rated as "Good" for 10N / CUP or more and 20N / CUP or less, and "Poor" for less than 10N / CUP or more than 20N / CUP. The resealability was evaluated as "good" when it was 1.0 to 5.0 N / CUP, and as "poor" when it was less than 1.0 N / CUP or more than 5.0 N / CUP. Furthermore, in the four tests in total, Test Example 1 and Test Example 2, if there was even one "X" the overall evaluation was recorded as "X", and if all were "○" or "◎", the overall evaluation was recorded as "○".

[0082] [Table 1]

[0083] As is clear from the results in Table 1, the lid material of the present invention is excellent in adhesion, openability and resealability even when the container flange is narrow, having a width of just a few millimeters.

Claims

1. A laminate comprising a pressure-sensitive adhesive layer and a sealant layer in this order on at least one surface of a base layer, (1) The adhesive layer has a dry weight of 10 to 50 g / m ２ and containing an acrylic adhesive, (2) The sealant layer includes a cyclic olefin copolymer-containing layer and a polyolefin resin-containing layer in this order from the side closest to the pressure-sensitive adhesive layer. A packaging material characterized by:

2. The packaging material according to claim 1, wherein the sealant layer has a thickness of 20 to 60 μm.

3. The lid material according to claim 1 , wherein the sealant layer further contains a polyolefin resin (excluding cyclic olefin copolymers).

4. 2. The lid material according to claim 1, wherein the cyclic olefin copolymer is a copolymer of norbornene and ethylene, and the polyolefin resin contains a polyethylene resin.

5. 2. The lid material according to claim 1, wherein the substrate layer is made of at least one material selected from the group consisting of plastics, rubber, metal, glass, ceramics, and paper.

6. A lid material comprising the packaging material according to any one of claims 1 to 5.

7. The lid material according to claim 6, which is used to heat-seal a flange portion formed at an opening of a container to the sealant layer.

8. A sealed product in which a flange portion formed at the opening of a container containing contents and the sealant layer of the lid material according to claim 6 are heat-sealed.

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