Easy-open film, lid material, and packaging

Abstract

To provide an easy-open film, lid material, and packaging that can improve the balance between heat seal strength and zip-stopping performance. [Solution] An easy-open film 50 having a sealing layer 10, wherein the blocking force between the sealing layers 10 is 70N / 5.2cm 2 The following is an easy-open film 50.

Description

Technical Field

[0001] The present invention relates to an easily unsealable film, a lid material, and a package.

Background Art

[0002] Easily unsealable films are known. As technologies related to easily unsealable films, for example, those described in Patent Documents 1 and 2 can be mentioned.

[0003] Patent Document 1 has an object of providing an adhesive resin composition that achieves both adhesion to a container having at least a resin surface material and easy and smooth peelability at the time of peeling after adhesion. It contains at least one resin A of an ethylene polymer and an ethylene-vinyl acetate copolymer, a resin B incompatible with the resin A, and a tackifying resin. The adhesive resin composition has a tensile strength of 2 MPa or more and 15 MPa or less and an elongation of 50% or more and 500% or less when measured at a thickness of 2 mm in accordance with JIS-K6760.

[0004] Patent Document 2 has an object of providing an adhesive resin composition that is particularly excellent in interfacial peeling at the time of opening with respect to a PET container, and has excellent slip stick and container adhesion resistance, and a sheet, a lid material, a container, etc. in which a film of the adhesive resin composition is laminated. It describes an adhesive resin composition containing 20 to 90% by mass of an ethylene-α-olefin copolymer (A) having a density of 0.870 to 0.910 g / cm , , , ,

[0005] , , , 0 to 60% by mass of low-density polyethylene (B), and 5 to 25% by mass of a tackifying resin (C).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

[0006] Our investigations revealed that there is room for improvement in the balance between the heat seal strength against the adherend and the reduction of the ripping sensation when opening the package (hereinafter referred to as "zipping"). The present invention provides an easy-open film, lid material, and packaging that can improve the balance between heat seal strength and zip-suppression performance. [Means for solving the problem]

[0007] The inventors diligently conducted research to achieve the above objectives. As a result, they discovered that by incorporating a sealing layer and setting the blocking force of the sealing layer, measured by a specific method, within a specific numerical range, it is possible to improve the balance between the heat seal strength and zip suppression performance of an easily openable film, thus completing the present invention.

[0008] According to the present invention, the following easy-open film, lid material, and packaging are provided.

[0009] [1] An easily tamper-evident film having a sealing layer, The blocking force between the above sealing layers according to the following (Method 1) is 70 N / 5.2 cm 2 The following is an easy-open film. (Method 1) A 15 μm thick nylon film is laminated onto a 12 μm thick biaxially oriented polyethylene terephthalate film (PET film) using dry lamination with a urethane adhesive. Next, one side of the easy-open film is laminated onto the side of the nylon film that is not in contact with the PET film using dry lamination with a urethane adhesive, preparing a laminated film in which the PET film and the seal layer are the outermost layers. Then, the laminated film is cut to create strip-shaped test pieces measuring 20 mm x 100 mm in width. Next, five laminates are prepared by overlapping the seal layers of the test pieces. Then, near the center of the laminates, a 26 mm x 76 mm microscope slide is used to sandwich the laminates so that the laminates and the microscope slides are at a right angle. The overlapping area of ​​the laminates and the microscope slides is 5.2 cm. 2 A load of 4 kg is placed on the area, and it is aged at 40°C for 24 hours, then allowed to cool. After cooling, the peel strength between the seal layers of the laminate is evaluated separately using a universal tensile testing machine at a crosshead speed of 300 mm / min and the shear peel method, and the maximum strength is calculated. The above maximum strength is evaluated for n=5, and the average value is used as the blocking force (N / 5.2cm). 2 ) [2] The easy-open film according to [1] above, wherein the sealing layer contains an ethylene-vinyl acetate copolymer. [3] The easy-open film according to [2] above, wherein the content of the ethylene-vinyl acetate copolymer in the sealing layer is 20% by mass or more and 100% by mass or less when the entire sealing layer is considered to be 100% by mass. [4] The easy-open film according to [2] or [3] above, wherein the sealing layer contains an incompatible resin that is incompatible with the ethylene-vinyl acetate copolymer. [5] The easy-open film according to [4] above, wherein the non-compatible resin comprises one or more selected from the group consisting of polyethylene terephthalate, polystyrene, and polyolefin. [6] The easy-open film according to [4] or [5] above, wherein the content of the incompatible resin in the seal layer is 1% by mass or more and 70% by mass or less when the entire seal layer is considered to be 100% by mass. [7] An easy-open film according to any one of [1] to [6] above, wherein the sealing layer contains an antiblocking agent. [8] The easy-open film according to [7], wherein the content of the antiblocking agent in the sealing layer is 0.1% by mass or more and 20% by mass or less when the entire sealing layer is considered as 100% by mass. [9] An easy-open film according to any of [1] to [8] above, wherein the thickness of the sealing layer is 1 μm or more and 50 μm or less.

[10] An easily openable film according to any of the above [1] to [9], further comprising a support layer.

[11] The easy-open film according to

[10] above, wherein the support layer contains polyolefin.

[12] The easy-open film according to

[11] , wherein the polyolefin in the support layer comprises one or more selected from the group consisting of polyethylene and polypropylene.

[13] An easy-open film according to any of

[10] to

[12] above, wherein the thickness of the support layer is 5 μm or more and 150 μm or less.

[14] An easily tamperable film according to any of

[10] to

[13] above, wherein the support layer comprises a core layer and a laminate layer.

[15] The easy-open film according to

[14] above, wherein the core layer contains a polyolefin.

[16] The easy-open film according to

[15] , wherein the polyolefin in the core layer comprises one or more selected from the group consisting of polyethylene and polypropylene.

[17] An easy-open film according to any of

[14] to

[16] above, wherein the thickness of the core layer is 3 μm or more and 100 μm or less.

[18] An easy-open film according to any of

[14] to

[17] above, wherein the laminate layer contains polyolefin.

[19] The easy-open film according to

[18] , wherein the polyolefin in the laminate layer comprises one or more selected from the group consisting of polyethylene and polypropylene.

[20] An easy-open film according to any of

[14] to

[19] above, wherein the laminate layer further contains a slip agent. [twenty one] The easy-open film according to

[20] , wherein the content of the slip agent in the laminate layer is 0.01% by mass or more and 2.00% by mass or less, when the entire laminate layer is considered to be 100% by mass. [twenty two] An easy-open film according to any of

[14] to

[21] above, wherein the thickness of the laminate layer is 2 μm or more and 50 μm or less. [twenty three] An easy-open film according to any of the above [1] to

[22] , which can be used on an adherend containing one or more selected from the group consisting of polyethylene terephthalate, polystyrene, polyethylene, and polypropylene. [twenty four] An easy-open film according to any of the above [1] to

[23] , wherein the heat seal strength by the following method (Method 2) is 5N / 15mm or more and 50N / 15mm or less. (Method 2) A laminate is obtained by bonding a 12 μm thick biaxially oriented polyethylene terephthalate film, a 7 μm thick aluminum foil, another 12 μm thick biaxially oriented polyethylene terephthalate film, and the above-mentioned easy-open film in this order using a urethane-based adhesive. Next, a 400 μm thick amorphous polyethylene terephthalate sheet (A-PET) is placed on the seal layer side of the easy-open film in the laminate as the adherend. The laminate and adherend are heat-sealed for 1 second using a heat sealer at a temperature of 180°C and a pressure of 0.2 MPa with a 5 mm wide sealing bar, and then allowed to cool. After that, a 15 mm wide test piece is cut from the heat-sealed laminate and adherend, and the adherend is peeled off in a 180-degree direction using a universal tensile testing machine at a constant temperature of 23°C and 50% RH at a tensile speed of 500 mm / min. The maximum load is measured and the heat seal strength (N / 15 mm) for A-PET is determined. [twenty five] An easy-to-open film according to any of the above [1] to

[24] , wherein the tensile modulus T1 in the MD direction, determined by the following method (Method 3), is 10 MPa or more and 2000 MPa or less. (Method 3) A 15mm x 15cm test specimen is cut from the above-mentioned easy-open film. Then, in accordance with JIS K7127:1999, the tensile modulus T1 (MPa) in the MD direction of the test specimen is measured under the conditions of a measurement temperature of 23±2℃, 50±5%RH, and a tensile speed of 5mm / min.

[26] An easy-to-open film according to any of the above [1] to

[25] , wherein the tensile modulus T2 in the TD direction, determined by the following method (Method 4), is 10 MPa or more and 2000 MPa or less. (Method 4) A 15mm x 15cm test specimen is cut from the above-mentioned easy-open film. Then, in accordance with JIS K7127:1999, the tensile modulus T2 (MPa) in the TD direction of the test specimen is measured under the conditions of a measurement temperature of 23±2℃, 50±5%RH, and a tensile speed of 5mm / min.

[27] A lid material containing an easily openable film as described in any of the above [1] to

[26] .

[28] A lid material comprising, in this order, a base layer, an adhesive layer, and an easy-open film as described in any of [1] to

[26] above.

[29] The lid material described in

[27] or

[28] above, and the container, A package in which the easy-open film in the lid material is sealed to the container.

[30] The packaging according to

[29] above, wherein the container comprises one or more selected from the group consisting of polyethylene terephthalate, polystyrene, polyethylene, and polypropylene. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide an easy-open film, lid material, and packaging body that can improve the balance between heat seal strength and zip-suppression performance. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic cross-sectional view showing an example of the structure of an easy-open film according to an embodiment of the present invention. [Figure 2] This is a schematic cross-sectional view showing an example of the structure of an easy-open film according to an embodiment of the present invention. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will be described below with reference to the drawings. In all drawings, similar components are denoted by the same reference numeral, and explanations are omitted where appropriate. Furthermore, the drawings are schematic and do not necessarily correspond to actual dimensional proportions. In the specification, unless otherwise specified, the notation "A to B" regarding a numerical range means A or greater and B or less. For example, 1 to 5% means 1% or greater and 5% or less. In this specification, "(meth)acrylic" means acrylic, methacrylic, or both acrylic and methacrylic.

[0013] <Easy-open film 50> As shown in Figure 1, the easy-open film 50 of this embodiment is an easy-open film 50 comprising a seal layer 10, wherein the blocking force between the seal layers 10 by the following (Method 1) is 70 N / 5.2 cm 2 The following applies:

[0014] (Method 1) A 15 μm thick nylon film is laminated onto a 12 μm thick biaxially oriented polyethylene terephthalate film (PET film) using dry lamination with a urethane adhesive. Next, one side of the easy-open film is laminated onto the side of the nylon film that is not in contact with the PET film using dry lamination with a urethane adhesive, preparing a laminated film in which the PET film and the seal layer are the outermost layers. Then, the laminated film is cut to create strip-shaped test pieces measuring 20 mm x 100 mm in width. Next, five laminates are prepared by overlapping the seal layers of the test pieces. Then, near the center of the laminates, a 26 mm x 76 mm microscope slide is used to sandwich the laminates so that the laminates and the microscope slides are at a right angle. The overlapping area of ​​the laminates and the microscope slides is 5.2 cm. 2 A load of 4 kg is placed on the area, and it is aged at 40°C for 24 hours, then allowed to cool. After cooling, the peel strength between the seal layers of the laminate is evaluated separately using a universal tensile testing machine at a crosshead speed of 300 mm / min and the shear peel method, and the maximum strength is calculated. The above maximum strength is evaluated for n=5, and the average value is used as the blocking force (N / 5.2cm). 2 )

[0015] The easy-opening film 50 of this embodiment includes a seal layer 10. By making the blocking force between the seal layers 10 measured by a specific method not exceed the upper limit value, the heat-seal strength of the easy-opening film 50 and the performance balance of dip suppression can be improved. Although the reason for this is not clear, by making the blocking force between the seal layers 10 having heat-sealability not exceed the upper limit value, the tensile load when peeling the easy-opening film 50 is evenly applied, and as a result, it is considered that the performance balance of heat-seal strength and dip suppression can be improved.

[0016] From the viewpoint of further improving the performance balance of heat-seal strength and dip suppression of the easy-opening film 50 of this embodiment, the blocking force between the seal layers 10 by the above (Method 1) is preferably 68 N / 5.2 cm 2 More preferably, it is 66 N / 5.2 cm or less 2 Even more preferably, it is 64 N / 5.2 cm or less 2 Even more preferably, it is 62 N / 5.2 cm or less 2 Even more preferably, it is 60 N / 5.2 cm or less 2 And so on. The lower limit value of the blocking force is not particularly limited, but it may be 0 N / 5.2 cm 2 Or more, or 1 N / 5.2 cm 2 Or more, or 2 N / 5.2 cm 2 Or more, or 3 N / 5.2 cm 2 Or more, or 4 N / 5.2 cm 2 Or more. From the above, from the viewpoint of further improving the performance balance of heat-seal strength and dip suppression, the blocking force is preferably 0 N / 5.2 cm 2 Or more and 70 N / 5.2 cm or less, more preferably 0 N / 5.2 cm 2 Or more and 68 N / 5.2 cm or less, even more preferably 1 N / 5.2 cm 2 Or more and 66 N / 5.2 cm or less, even more preferably 2 N / 5.2 cm 2 Or more and 64 N / 5.2 cm or less​​​​​​2 More preferably, 3N / 5.2cm 2 Above 62N / 5.2cm 2 More preferably, 4N / 5.2cm 2 Above 60N / 5.2cm 2 The following applies:

[0017] In the easily detachable film 50 of this embodiment, the blocking force between the sealing layers 10 according to (Method 1) can be controlled by adjusting the type, amount, and thickness of the components of the sealing layer 10.

[0018] In this embodiment, the Young's modulus of the sealing layer 10 of the easy-open film 50, prepared according to the following method (Method A), is preferably 88 MPa or higher, more preferably 90 MPa or higher, even more preferably 95 MPa or higher, even more preferably 100 MPa or higher, even more preferably 110 MPa or higher, even more preferably 120 MPa or higher, even more preferably 130 MPa or higher, and even more preferably 140 MPa or higher, from the viewpoint of further improving the balance between heat seal strength and zip suppression performance. The upper limit of the Young's modulus is not particularly limited, but may be 1000 MPa or lower, 750 MPa or lower, 500 MPa or lower, 400 MPa or lower, or 300 MPa or lower. From the viewpoint of further improving the balance between heat seal strength and zip suppression performance, the Young's modulus is preferably 88 MPa to 1000 MPa, more preferably 88 MPa to 750 MPa, even more preferably 90 MPa to 500 MPa, even more preferably 95 MPa to 400 MPa, even more preferably 100 MPa to 300 MPa, even more preferably 110 MPa to 300 MPa, even more preferably 120 MPa to 300 MPa, even more preferably 130 MPa to 300 MPa, and even more preferably 140 MPa to 300 MPa.

[0019] (Method A) The Young's modulus of the seal layer 10 of the above-mentioned easy-open film 50, which measures 1 cm in length and 1 cm in width, is measured by the nanoindentation method under the following conditions. • Measurement mode: Continuous stiffness measurement method (CSM / CSR) • Indenter: Diamond triangular pyramidal indenter • Strain rate: 0.2 [1 / s] • Indenter vibration frequency: 110 [Hz] • Indenter vibration amplitude: 2 [nm] Poisson's ratio: 0.35 • Young's modulus calculation depth: 500 [nm]

[0020] In the easily detachable film 50 of this embodiment, the Young's modulus of the sealing layer 10 by (Method A) can be controlled by adjusting the type, amount, and thickness of the components of the sealing layer 10.

[0021] From the viewpoint of further improving the balance between heat seal strength and zip suppression performance, the heat seal strength of the easy-open film 50 of this embodiment is preferably 5N / 15mm or more and 50N / 15mm or less, more preferably 6N / 15mm or more and 45N / 15mm or less, even more preferably 7N / 15mm or more and 40N / 15mm or less, even more preferably 8N / 15mm or more and 35N / 15mm or less, even more preferably 9N / 15mm or more and 30N / 15mm or less, and even more preferably 10N / 15mm or more and 25N / 15mm or less.

[0022] (Method 2) A laminate is obtained by bonding a 12 μm thick biaxially oriented polyethylene terephthalate film, a 7 μm thick aluminum foil, another 12 μm thick biaxially oriented polyethylene terephthalate film, and the above-mentioned easy-open film in this order using a urethane-based adhesive. Next, a 400 μm thick amorphous polyethylene terephthalate sheet (A-PET) is placed on the seal layer side of the easy-open film in the laminate as the adherend. The laminate and adherend are heat-sealed for 1 second using a heat sealer at a temperature of 180°C and a pressure of 0.2 MPa with a 5 mm wide sealing bar, and then allowed to cool. After that, a 15 mm wide test piece is cut from the heat-sealed laminate and adherend, and the adherend is peeled off in a 180-degree direction using a universal tensile testing machine at a constant temperature of 23°C and 50% RH at a tensile speed of 500 mm / min. The maximum load is measured and the heat seal strength (N / 15 mm) for A-PET is determined.

[0023] The heat seal strength of the easily openable film 50 of this embodiment by (Method 2) can be controlled by adjusting the type, amount, and thickness of the components of the seal layer 10. Furthermore, if the easy-open film 50 of this embodiment further includes a support layer 20 in addition to the seal layer 10, preferably an amorphous polyethylene terephthalate sheet (A-PET) is laminated to the seal layer 10 side of the easy-open film 50, and a biaxially oriented polyethylene terephthalate film with a thickness of 12 μm is laminated to the support layer 20 side of the easy-open film 50. Also, if the support layer 20 of the easy-open film 50 of this embodiment includes a core layer 21 and a laminate layer 22, more preferably an amorphous polyethylene terephthalate sheet (A-PET) is laminated to the seal layer 10 side of the easy-open film 50, and a biaxially oriented polyethylene terephthalate film with a thickness of 12 μm is laminated to the laminate layer 22 side of the easy-open film 50. In this case, possible methods for laminating the easily openable film 50 with the amorphous polyethylene terephthalate sheet (A-PET) or biaxially oriented polyethylene terephthalate film include, for example, using an adhesive or using a sealing bar for heat fusion.

[0024] In this embodiment, the easily openable film 50 has a tensile modulus T1 in the MD direction, determined by the following method (Method 3), which is preferable to a balance between heat seal strength and zip suppression performance.

[0025] (Method 3) A 15mm x 15cm test piece is cut from the above-mentioned easy-open film 50. Then, in accordance with JIS K7127:1999, the tensile modulus T1 (MPa) in the MD direction of the test piece is measured under the conditions of a measurement temperature of 23±2℃, 50±5%RH, and a tensile speed of 5mm / min.

[0026] The tensile modulus T1 in the MD direction of the easily openable film 50 of this embodiment, according to (Method 3), can be controlled by adjusting the type, amount, and thickness of the components of the seal layer 10. Furthermore, if the easily openable film 50 of this embodiment includes a support layer 20 and other layers, it can also be controlled by adjusting the type, amount, and thickness of the components of the support layer 20 and other layers.

[0027] In this embodiment, the easily openable film 50 has a tensile modulus T2 in the TD direction, determined by the following method (Method 4), which is preferable to a balance between heat seal strength and zip suppression performance.

[0028] (Method 4) A 15mm x 15cm test piece is cut from the above-mentioned easy-open film 50. Then, in accordance with JIS K7127:1999, the tensile modulus T2 (MPa) in the TD direction of the test piece is measured under the conditions of a measurement temperature of 23±2℃, 50±5%RH, and a tensile speed of 5mm / min.

[0029] The tensile modulus T2 in the TD direction of the easy-open film 50 of this embodiment, according to (Method 4), can be controlled by adjusting the type, amount, and thickness of the components of the seal layer 10. Furthermore, if the easy-open film 50 of this embodiment includes a support layer 20 and other layers, it can also be controlled by adjusting the type, amount, and thickness of the components of the support layer 20 and other layers.

[0030] The thickness of the easy-open film 50 in this embodiment is not particularly limited, but can be arbitrarily set according to desired purposes such as cost, mechanical strength, and transparency. From the viewpoint of further improving the balance of performance in terms of bag-making properties, mechanical properties, handling, appearance, transparency, heat sealability, moldability, and lightweight, the thickness of the easy-open film 50 in this embodiment is preferably 6 μm to 200 μm, more preferably 10 μm to 150 μm, even more preferably 15 μm to 100 μm, even more preferably 20 μm to 75 μm, and even more preferably 25 μm to 50 μm.

[0031] The easily openable film 50 of this embodiment has an improved balance of heat seal strength and zip-suppression performance, and therefore can preferably be used on adherends containing one or more selected from the group consisting of polyethylene terephthalate, polystyrene, polyethylene, and polypropylene.

[0032] The following describes each layer that makes up the easy-open film 50.

[0033] [Seal layer 10] As shown in Figure 1, the easily openable film 50 of this embodiment includes a sealing layer 10. The sealing layer 10 adheres closely to the object to be adhered to and has the function of sealing the object to be adhered to. The sealing layer 10 may be a single layer or multiple layers, but it is preferably a single layer from the viewpoint of simplifying the manufacturing process of the easy-open film 50. Furthermore, the seal layer 10 may be unstretched, or uniaxially stretched or biaxially stretched, but it is preferably unstretched from the viewpoint of further improving the balance of mechanical properties, heat seal strength, and zip-suppression performance of the easy-open film 50.

[0034] The sealing layer 10 preferably contains an ethylene-vinyl acetate copolymer, from the viewpoint of further improving the balance between heat seal strength and zip suppression performance. Since the ethylene-vinyl acetate copolymer has excellent heat sealability and excellent adhesion to the adherend, it can improve the heat seal strength of the easy-open film 50.

[0035] The ethylene-vinyl acetate copolymer of this embodiment is a copolymer of ethylene and vinyl acetate, for example, a random copolymer. The ethylene-vinyl acetate copolymer is preferably a binary copolymer consisting only of ethylene and vinyl acetate, but in addition to ethylene and vinyl acetate, it may also contain at least one copolymer component selected from vinyl ester monomers such as vinyl formate, vinyl glycolate, vinyl propionate, vinyl benzoate, etc.; acrylic monomers such as acrylic acid, methacrylic acid, ethacrylic acid, or their salts or alkyl esters; etc. When copolymer components other than ethylene and vinyl acetate are included, the content of the copolymer components other than ethylene and vinyl acetate in the ethylene-vinyl acetate copolymer is preferably 0.5% by mass or more and 5% by mass or less.

[0036] In accordance with JIS K7210:1999, the melt flow rate (MFR) of the ethylene-vinyl acetate copolymer, measured under conditions of 190°C and a 2.16 kg load, is preferably 0.1 g / 10 min to 50 g / 10 min, more preferably 0.5 g / 10 min to 50 g / 10 min, even more preferably 1.0 g / 10 min to 45 g / 10 min, even more preferably 1.5 g / 10 min to 40 g / 10 min, and even more preferably 2.0 g / 10 min to 35 g / 10 min, from the viewpoint of further improving the balance of performance of the moldability of the seal layer 10, the heat seal strength of the easy-open film 50, and the zip suppression.

[0037] Examples of such ethylene-vinyl acetate copolymers include the CMPS® series, CMPS® series and Evaflex® series from Mitsui Dow Polychemicals, and the Hirodyne series from Yasuhara Chemical Co., Ltd.

[0038] From the viewpoint of further improving the balance between the heat seal strength and zip suppression performance of the easy-open film 50, the content of the ethylene-vinyl acetate copolymer in the seal layer 10 is preferably 20% to 100% by mass, more preferably 25% to 99% by mass, even more preferably 30% to 98% by mass, even more preferably 35% to 97% by mass, even more preferably 40% to 96% by mass, and even more preferably 45% to 95% by mass, when the entire seal layer 10 is considered as 100% by mass.

[0039] From the viewpoint of further improving the balance between the heat seal strength and zip suppression performance of the easy-open film 50, the sealing layer 10 preferably contains an incompatible resin that is incompatible with the ethylene-vinyl acetate copolymer. The sealing layer 10 using an incompatible resin exhibits improved blocking force compared to the sealing layer 10 containing only an ethylene-vinyl acetate copolymer, as described above (Method 1). As a result, the zipping of the easy-open film 50 can be further suppressed.

[0040] The incompatible resin preferably includes one or more selected from the group consisting of polyethylene terephthalate, polystyrene, and polyolefin, from the viewpoint of further improving the balance between the heat seal strength and zip suppression performance of the easy-open film 50. The polyethylene terephthalate preferably comprises one or more types selected from the group consisting of crystalline polyethylene terephthalate and amorphous polyethylene terephthalate. The polystyrene preferably includes one or more styrene monomer homopolymers containing one or more selected from the group consisting of styrene, methylstyrene, ethylstyrene, isopropylstyrene, dimethylstyrene, paramethylstyrene, chlorostyrene, bromostyrene, vinyltoluene, and vinylxylene; acrylonitrile-styrene copolymer (AS); methyl methacrylate-styrene copolymer; acrylonitrile-methyl methacrylate-styrene copolymer; acrylonitrile-butadiene-styrene copolymer (ABS); acrylonitrile-acrylic rubber-styrene copolymer (AAS); and acrylonitrile-ethylene propylene diene rubber-styrene copolymer (AES). The polyolefin preferably includes one or more selected from the group consisting of high-density polyethylene, low-density polyethylene, linear low-density polyethylene, propylene homopolymer, propylene-α-olefin copolymer, poly(4-methyl-1-pentene), and poly(1-butene). The propylene-α-olefin copolymer may be random polypropylene or block polypropylene. In the propylene-α-olefin copolymer, the α-olefin copolymerizable with propylene preferably includes one or more selected from the group consisting of ethylene and α-olefins with about 4 to 20 carbon atoms, such as ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, and 4-methyl-1-pentene, from the viewpoint of further improving the balance between the heat seal strength and zip suppression performance of the easy-open film 50.

[0041] From the viewpoint of further improving the balance between the heat seal strength and zip-suppression performance of the easy-open film 50, the density of the incompatible resin is preferably 886 kg / m³. 3 More preferably 887 kg / m 3 More preferably 888 kg / m 3 More preferably 890 kg / m 3 More preferably 900 kg / m 3 More preferably 950 kg / m 3 More preferably 1000 kg / m 3 The above is true, and preferably 3000 kg / m 3 More preferably, 2500 kg / m 3 More preferably, 2000 kg / m 3 More preferably, 1800 kg / m 3 More preferably, 1600 kg / m 3 More preferably, 1400 kg / m 3 The following applies: Based on the above, the density of the incompatible resin is preferably 886 kg / m³ from the viewpoint of further improving the balance between the heat seal strength and zip suppression performance of the easy-open film 50. 3 More than 3000kg / m 3 More preferably 886 kg / m 3 More than 3000kg / m 3 More preferably, 887 kg / m 3 More than 3000kg / m 3 Further preferable, 888 kg / m 3 More than 2500kg / m 3 More preferably, 890 kg / m 3 More than 2000kg / m 3 More preferably, 900 kg / m 3 More than 1800kg / m 3 More preferably, 950 kg / m 3 More than 1600kg / m 3 More preferably, 1000 kg / m 3 More than 1400kg / m 3 The following applies:

[0042] Examples of such miscible resins include the Byron® series from Toyobo Co., Ltd., the Eastar® series from Eastman Chemical Co., Ltd., the ECOZEN series from SK Chemical Co., Ltd., the GPPS series from PS Japan Co., Ltd., the Hyzex® series from Prime Polymer Co., Ltd., and the Admer® series from Mitsui Chemicals, Inc.

[0043] From the viewpoint of further improving the balance between the heat seal strength and zip suppression performance of the easy-open film 50, the content of the incompatible resin in the seal layer 10 is preferably 1% to 70% by mass, more preferably 2% to 60% by mass, and even more preferably 3% to 50% by mass, when the entire seal layer 10 is considered to be 100% by mass.

[0044] The sealing layer 10 preferably contains an antiblocking agent, from the viewpoint of further improving the balance between heat seal strength and zip suppression performance. By including an antiblocking agent in the sealing layer 10, blocking between the sealing layers 10 can be suppressed, improving the storability of the easy-open film 50. In addition, the inclusion of an antiblocking agent in the sealing layer 10 makes the sealing layer 10 harder, improving the blocking force as described above (Method 1). As a result, zipping of the easy-open film 50 can be further suppressed.

[0045] From the viewpoint of further improving the balance of storability, heat seal strength, and zip-suppression performance of the easy-open film 50, the antiblocking agent preferably comprises one or more selected from the group consisting of talc, silica, clay, calcium carbonate, zeolite, erucic acid amide, starch, aluminum oxide, acrylic resin, methacrylic resin, silicone resin, and polytetrafluoroethylene resin.

[0046] The antiblocking agent may be added in the form of a masterbatch. From the viewpoint of affinity with the components constituting the seal layer 10, the antiblocking agent is preferably in the form of a masterbatch containing an ethylene-vinyl acetate copolymer as the base resin.

[0047] From the viewpoint of further improving the balance of storage performance, heat seal strength, and zip suppression performance of the easy-open film 50, the content of the antiblocking agent in the seal layer 10 is preferably 0.1% to 20% by mass, more preferably 0.5% to 10% by mass, even more preferably 1.0% to 5% by mass, and even more preferably 1.5% to 3% by mass, when the entire seal layer 10 is considered as 100% by mass. Furthermore, if the antiblocking agent is in the form of a masterbatch, the above numerical range refers to the content of the component that substantially acts as an antiblocking agent, excluding the base resin.

[0048] The sealing layer 10 may contain other components besides those described above, as long as they do not impair the purpose of this disclosure. Other components include, for example, tackifiers, dispersants, heat stabilizers, weather stabilizers, UV absorbers, lubricants, nucleating agents, antistatic agents, antifogging agents, pigments, and dyes.

[0049] Among these, the sealing layer 10 preferably includes a tackifier, from the viewpoint of further improving the balance between heat seal strength and zip suppression performance. Tackifiers are generally resinous substances that have the property of imparting tackiness and are manufactured and sold as such. From the viewpoint of further improving the balance between heat seal strength and zip suppression performance, the tackifier preferably includes one or more selected from the group consisting of aliphatic hydrocarbon resins, alicyclic hydrocarbon resins, aromatic hydrocarbon resins, polyterpene resins, rosins, styrene resins, and coumarone-indene resins.

[0050] Aliphatic hydrocarbon resins preferably include resins obtained by polymerizing a fraction containing one or more elements selected from the group consisting of mono- and diolefins having 4 to 5 carbon atoms, such as 1-butene, isobutene, butadiene, 1,3-pentadiene, and isoprene.

[0051] The alicyclic hydrocarbon resin preferably includes one or more selected from the group consisting of resins obtained by cyclization-dimerization and polymerization of diene components in the spent C4-C5 fraction, resins obtained by polymerization of cyclic monomers such as cyclopentadiene, and resins obtained by intranuclear hydrogenation of aromatic hydrocarbon resins.

[0052] The aromatic hydrocarbon resin preferably includes one or more resins selected from the group consisting of a fraction containing one or more C8-C10 vinyl aromatic hydrocarbons such as vinyltoluene, indene, and α-methylstyrene, and resins obtained by copolymerizing these fractions with the above aliphatic hydrocarbon fraction.

[0053] The polyterpene resin preferably comprises one or more selected from the group consisting of α-pinene polymers, β-pinene polymers, dipentene polymers, terpene-phenol copolymers, α-pinene-phenol copolymers, and hydrogenated versions thereof.

[0054] Rosins preferably include one or more selected from the group consisting of rosins such as gum rosin, wood rosin, and tall oil, and their modified products. Examples of modified products include those that have been modified by hydrogenation, disproportionation, dimerization, esterification, etc.

[0055] The styrene-based resin preferably includes a low molecular weight resinous polymer obtained by polymerizing one or more styrene-based monomers such as high-purity styrene, vinyltoluene, α-methylstyrene, and isopropyltoluene.

[0056] If the sealing layer 10 of this embodiment contains other components, the content of these other components may be any value as long as it does not impair the purpose of this disclosure, for example, 0.01% by mass or more and 10% by mass or less.

[0057] The thickness of the seal layer 10 in this embodiment is preferably 1 μm to 50 μm, more preferably 1 μm to 40 μm, even more preferably 2 μm to 30 μm, and even more preferably 3 μm to 20 μm, from the viewpoint of further improving the balance between heat seal strength and zip suppression performance.

[0058] [Support layer 20] As shown in Figure 2, the easy-open film 50 of this embodiment preferably further comprises a support layer 20, from the viewpoint of further improving the balance between heat seal strength and zip suppression performance. The support layer 20 has the function of improving the balance between the mechanical properties and heat seal strength performance of the easy-open film 50. The support layer 20 may be unstretched, or it may be uniaxially stretched or biaxially stretched, but it is preferably unstretched from the viewpoint of further improving the balance of the mechanical properties, heat seal strength, and zip-suppression performance of the easy-open film 50.

[0059] The support layer 20 preferably contains a thermoplastic resin, from the viewpoint of further improving the balance between heat seal strength and zip suppression performance. The thermoplastic resin contains one or more selected from the group consisting of polyolefins, polyesters, polyamides, polyacrylates, polymethacrylates, polyvinyl chlorides, polyvinylidene chlorides, polyimides, polyetherimides, polyacrylonitriles, polycarbonates, polystyrenes, ionomers, polysulfones, polyethersulfones, and polyphenylene ethers, from the viewpoint of further improving the balance between heat seal strength and zip suppression performance. Among these, the support layer 20 preferably contains polyolefin from the viewpoint of further improving the balance between heat seal strength and zip suppression performance.

[0060] From the viewpoint of further improving the balance between heat seal strength and zip suppression performance, the polyolefin preferably comprises one or more selected from the group consisting of polyethylene, polypropylene, poly(4-methyl-1-pentene), and poly(1-butene), and more preferably comprises one or more selected from the group consisting of polyethylene and polypropylene.

[0061] The polyethylene preferably includes one or more types selected from the group consisting of high-density polyethylene, low-density polyethylene, and linear low-density polyethylene. Polypropylene preferably comprises one or more selected from the group consisting of propylene homopolymer, propylene-α-olefin copolymer, poly(4-methyl-1-pentene), and poly(1-butene). The propylene-α-olefin copolymer may be random polypropylene or block polypropylene. In the propylene-α-olefin copolymer, the α-olefin copolymerizable with propylene preferably includes one or more selected from the group consisting of ethylene and α-olefins with about 4 to 20 carbon atoms, such as ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, and 4-methyl-1-pentene, from the viewpoint of further improving the balance between the heat seal strength and zip suppression performance of the easy-open film 50.

[0062] Examples of such polyolefins include the Evolu® series, Ultzex® series, and Prime Polypro® series manufactured by Prime Polymer Co., Ltd.

[0063] In this embodiment, the thickness of the support layer 20 is preferably 5 μm to 150 μm, more preferably 7 μm to 100 μm, even more preferably 10 μm to 75 μm, even more preferably 15 μm to 50 μm, and even more preferably 20 μm to 30 μm, from the viewpoint of further improving the balance between heat seal strength and zip suppression performance.

[0064] As shown in Figure 2, the support layer 20 in the easily openable film 50 of this embodiment preferably includes a core layer 21 and a laminate layer 22, from the viewpoint of further improving the balance of processability, heat seal strength, and zip suppression performance of the easily openable film 50. When the support layer 20 includes a core layer 21 and a laminate layer 22, the easily openable film 50 of this embodiment preferably comprises a seal layer 10, a core layer 21, and a laminate layer 22 in this order. This configuration allows a slip agent, intended to improve the processability of the easy-open film 50, to be incorporated into the laminate layer 22 located on the surface of the support layer 20. This improves the processability of the easy-open film 50 while reducing manufacturing costs. Furthermore, the inclusion of a core layer 21 improves the balance between the mechanical properties and heat seal strength of the easy-open film 50. The following provides a more detailed explanation of each layer.

[0065] (Core layer 21) As shown in Figure 2, the support layer 20 of this embodiment preferably further comprises a core layer 21 from the viewpoint of further improving the balance between heat seal strength and zip suppression performance. The core layer 21 has the function of improving the balance between the mechanical properties and heat seal strength performance of the easy-open film 50. The core layer 21 may be unstretched, or it may be uniaxially stretched or biaxially stretched, but it is preferably unstretched from the viewpoint of further improving the balance of mechanical properties, heat seal strength, and zip-suppression performance of the easy-open film 50.

[0066] The core layer 21 preferably contains a thermoplastic resin, from the viewpoint of further improving the balance between heat seal strength and zip suppression performance. The thermoplastic resin contains one or more selected from the group consisting of polyolefins, polyesters, polyamides, polyacrylates, polymethacrylates, polyvinyl chlorides, polyvinylidene chlorides, polyimides, polyetherimides, polyacrylonitriles, polycarbonates, polystyrenes, ionomers, polysulfones, polyethersulfones, and polyphenylene ethers, from the viewpoint of further improving the balance between heat seal strength and zip suppression performance. Among these, the core layer 21 preferably contains polyolefin from the viewpoint of further improving the balance between heat seal strength and zip suppression performance.

[0067] The polyolefin in the core layer 21 preferably comprises one or more selected from the group consisting of polyethylene, polypropylene, poly(4-methyl-1-pentene), and poly(1-butene), and more preferably comprises one or more selected from the group consisting of polyethylene and polypropylene, from the viewpoint of further improving the balance between heat seal strength and zip suppression performance.

[0068] The polyethylene in the core layer 21 preferably includes one or more types selected from the group consisting of high-density polyethylene, low-density polyethylene, and linear low-density polyethylene. The polypropylene in the core layer 21 preferably comprises one or more selected from the group consisting of propylene homopolymer, propylene-α-olefin copolymer, poly(4-methyl-1-pentene), and poly(1-butene). The propylene-α-olefin copolymer in the core layer 21 may be random polypropylene or block polypropylene. In the propylene-α-olefin copolymer in the core layer 21, the α-olefin copolymerizable with propylene preferably includes one or more selected from the group consisting of ethylene and α-olefins with about 4 to 20 carbon atoms, such as ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, and 4-methyl-1-pentene, from the viewpoint of further improving the balance between the heat seal strength and zip suppression performance of the easy-open film 50.

[0069] In this embodiment, the thickness of the core layer 21 is preferably 3 μm to 100 μm, more preferably 5 μm to 75 μm, even more preferably 7 μm to 50 μm, even more preferably 10 μm to 30 μm, and even more preferably 15 μm to 25 μm, from the viewpoint of further improving the balance between heat seal strength and zip suppression performance.

[0070] (Laminate layer 22) As shown in Figure 2, the support layer 20 of this embodiment preferably further comprises a laminate layer 22 from the viewpoint of further improving the balance between heat seal strength and zip suppression performance. The laminate layer 22 has the function of suppressing blocking of the easy-open film 50 and improving the balance of adhesive performance when the easy-open film 50 is used as two materials. The laminate layer 22 may be unstretched, or it may be uniaxially oriented or biaxially oriented, but it is preferably unstretched from the viewpoint of further improving the balance of mechanical properties, heat seal strength, and zip-suppression performance of the easy-open film 50.

[0071] The laminate layer 22 preferably contains a thermoplastic resin, from the viewpoint of further improving the balance between heat seal strength and zip suppression performance. The thermoplastic resin contains one or more selected from the group consisting of polyolefins, polyesters, polyamides, polyacrylates, polymethacrylates, polyvinyl chlorides, polyvinylidene chlorides, polyimides, polyetherimides, polyacrylonitriles, polycarbonates, polystyrenes, ionomers, polysulfones, polyethersulfones, and polyphenylene ethers, from the viewpoint of further improving the balance between heat seal strength and zip suppression performance. Among these, the laminate layer 22 preferably contains polyolefin from the viewpoint of further improving the balance between heat seal strength and zip suppression performance.

[0072] The polyolefin in the laminate layer 22 preferably comprises one or more selected from the group consisting of polyethylene, polypropylene, poly(4-methyl-1-pentene), and poly(1-butene), and more preferably comprises one or more selected from the group consisting of polyethylene and polypropylene, from the viewpoint of further improving the balance between heat seal strength and zip suppression performance.

[0073] The polyethylene in the laminate layer 22 preferably includes one or more types selected from the group consisting of high-density polyethylene, low-density polyethylene, and linear low-density polyethylene. The polypropylene in the laminate layer 22 preferably includes one or more selected from the group consisting of propylene homopolymer, propylene-α-olefin copolymer, poly(4-methyl-1-pentene), and poly(1-butene). The propylene-α-olefin copolymer in the laminate layer 22 may be random polypropylene or block polypropylene. In the propylene-α-olefin copolymer in the laminate layer 22, the α-olefin copolymerizable with propylene preferably includes one or more selected from the group consisting of ethylene and α-olefins with about 4 to 20 carbon atoms, such as ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, and 4-methyl-1-pentene, from the viewpoint of further improving the balance between the heat seal strength and zip suppression performance of the easy-open film 50.

[0074] The laminate layer 22 preferably contains a slip agent, from the viewpoint of further improving the balance of processability, storability, heat seal strength, and zip-suppression performance of the easy-open film 50.

[0075] From the viewpoint of further improving the balance of processability, storability, heat seal strength, and zip-suppression performance of the easy-open film 50, the slip agent preferably includes one or more selected from the group consisting of erucic acid amide, starch, acrylic resin, methacrylic resin, silicone resin, and polytetrafluoroethylene resin.

[0076] The slip agent may be added in the form of a masterbatch. From the viewpoint of affinity with the components constituting the laminate layer 22, the slip agent is preferably in the form of a masterbatch containing linear low-density polyethylene as the base resin.

[0077] From the viewpoint of further improving the balance of storage performance, heat seal strength, and zip suppression performance of the easy-open film 50, the content of the slip agent in the laminate layer 22 is preferably 0.01% to 2.00% by mass, more preferably 0.05% to 1.00% by mass, and even more preferably 0.10% to 0.50% by mass, when the entire laminate layer 22 is considered as 100% by mass. Furthermore, if the slip agent is in the form of a masterbatch, the above numerical range refers to the content of the component that substantially acts as a slip agent, excluding the base resin.

[0078] In this embodiment, the thickness of the laminate layer 22 is preferably 2 μm to 50 μm, more preferably 2 μm to 40 μm, even more preferably 2 μm to 30 μm, even more preferably 2 μm to 20 μm, and even more preferably 3 μm to 10 μm, from the viewpoint of further improving the balance between heat seal strength and zip suppression performance.

[0079] In this embodiment, the Young's modulus of the laminate layer 22 obtained by the following method (Method B) is preferably 200 MPa to 2000 MPa, more preferably 210 MPa to 1900 MPa, even more preferably 220 MPa to 1800 MPa, even more preferably 230 MPa to 1700 MPa, even more preferably 240 MPa to 1600 MPa, and even more preferably 250 MPa to 1500 MPa, from the viewpoint of further improving the balance between heat seal strength and zip suppression performance of the easy-open film 50.

[0080] (Method B) The Young's modulus of the laminate layer 22 of the above-mentioned easily openable film 50, which measures 1 cm vertically and 1 cm horizontally, is measured by the nanoindentation method under the following conditions. • Measurement mode: Continuous stiffness measurement method (CSM / CSR) • Indenter: Diamond triangular pyramidal indenter • Strain rate: 0.2 [1 / s] • Indenter vibration frequency: 110 [Hz] • Indenter vibration amplitude: 2 [nm] Poisson's ratio: 0.35 • Young's modulus calculation depth: 500 [nm]

[0081] The Young's modulus of the laminate layer 22 of the easily openable film 50 of this embodiment, obtained by (Method B), can be controlled by adjusting the type, amount, and thickness of the components of the laminate layer 22.

[0082] (Other layers) In the easily openable film 50 of this embodiment, an adhesive resin layer may be provided between the seal layer 10 and the support layer 20, between the seal layer 10 and the core layer 21, or between the core layer 21 and the laminate layer 22, from the viewpoint of further improving the performance balance of peel strength, heat seal strength, and zip suppression between each layer. As the adhesive resin in the adhesive resin layer, any known adhesive resin used as an adhesive can be used.

[0083] <Lid material> The easily openable film 50 of this embodiment can preferably be used as a lid material. That is, the lid material of this embodiment preferably includes the easily openable film 50 of this embodiment. When used as a lid for a container, the easy-open film 50 of this embodiment may be used as is, or it may be printed on before use. Depending on the application, it may also be pre-cut to match the shape of the container before being used as a lid.

[0084] From the viewpoint of further improving the balance between heat seal strength and zip suppression performance, the lid material of this embodiment preferably includes a base layer, an adhesive layer, and the easy-open film 50 of this embodiment in this order. In this case, from the viewpoint of further improving heat seal strength, it is preferable that the adhesive layer of the lid material and one surface of the seal layer 10 of the easy-open film 50 of this embodiment are in contact. If the easy-open film 50 of this embodiment includes a support layer 20, from the viewpoint of further improving heat seal strength, it is preferable that the adhesive layer of the lid material and the support layer 20 of the easy-open film 50 of this embodiment are in contact. If the support layer 20 of the easy-open film 50 of this embodiment includes a core layer 21 and a laminate layer 22, from the viewpoint of further improving heat seal strength, it is even more preferable that the adhesive layer of the lid material and the laminate layer 22 of the easy-open film 50 of this embodiment are in contact. The easily openable film 50 of this embodiment can be used as a lid material for containers, taking advantage of its easy-open properties, etc., by using the sealing layer 10 as the innermost layer on the container side.

[0085] The following describes each layer of the lid material of this embodiment, other than the easy-open film 50.

[0086] (base material layer) The lid material of this embodiment preferably includes a base layer, from the viewpoint of further improving the balance between heat seal strength and mechanical strength. There are no particular restrictions on the base layer; for example, a film commonly used for plastic packaging can be suitably used. The base layer preferably contains one or more selected from the following, from the viewpoint of further improving the balance of heat seal strength and mechanical strength: polyolefins such as polyethylene, polypropylene, poly(4-methyl-1-pentene), and poly(1-butene); polyesters such as amorphous polyethylene terephthalate, crystalline polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyamides such as nylon-6, nylon-66, and polymetaxylene adipamide; polyacrylate; polymethacrylate; polyvinyl chloride; polyvinylidene chloride; polyimide; polyetherimide; ethylene-vinyl acetate copolymer; polyacrylonitrile; polycarbonate; polystyrene; ionomer; polysulfone; polyethersulfone; and polyphenylene ether. More preferably, it contains one or more selected from the group consisting of amorphous polyethylene terephthalate, crystalline polyethylene terephthalate, polystyrene, polyamide, polyethylene, and polypropylene.

[0087] Depending on its application, the base layer may include layers made of metal foil such as aluminum, paper, cellophane, a layer coated with metal oxides, a layer coated with organic compounds, and a layer made of ethylene vinyl alcohol copolymer (EVOH) resin. The base layer may be used in its unstretched state, or it may be used after uniaxial stretching or biaxial stretching. Furthermore, the base layer may be a single layer consisting of one layer selected from the above-mentioned films and layers, or it may be a multilayer consisting of two or more layers. Among these, the base layer preferably includes one or more layers selected from the group consisting of biaxially oriented polyethylene terephthalate film / aluminum foil / biaxially oriented polyethylene terephthalate film, biaxially oriented polyethylene terephthalate film / biaxially oriented polyethylene terephthalate film, and biaxially oriented polyethylene terephthalate film / polyamide film, from the viewpoint of further improving the balance of heat seal strength and mechanical strength performance. The base layer may be surface-treated to improve adhesion with other layers. Specifically, corona treatment, plasma treatment, undercoat treatment, primer coating, etc., may be performed. Adhesives and anchoring agents may also be interposed between each layer of the base layer as needed. Furthermore, an ink layer may be provided on the base layer to express the design.

[0088] From the viewpoint of further improving the balance between heat seal strength and mechanical strength, the thickness of the base layer is preferably 5 μm to 1000 μm, more preferably 10 μm to 100 μm, even more preferably 20 μm to 50 μm, and even more preferably 30 μm to 40 μm.

[0089] There are no particular limitations on the method of laminating the base layer onto the easily openable film 50 of this embodiment, but examples include directly laminating the base layer onto the easily openable film 50 of this embodiment by extrusion lamination, or laminating by dry lamination via an adhesive layer, as described later. Among these, the method of laminating the base layer onto the easily openable film 50 of this embodiment is preferably the method of dry lamination via an adhesive layer, from the viewpoint of further improving the balance between heat seal strength and mechanical strength.

[0090] (adhesive layer) The lid material of this embodiment preferably includes an adhesive layer, from the viewpoint of further improving the balance of performance between the adhesiveness, heat seal strength, and mechanical strength between the base layer and the easy-open film 50 of this embodiment. The adhesive layer is a layer that functions as an adhesive when laminating the base layer and the easy-open film 50 of this embodiment by dry lamination or the like. From the viewpoint of further improving the balance of performance between the adhesiveness, heat seal strength, and mechanical strength between the substrate layer and the easily openable film 50 of this embodiment, the adhesive layer preferably includes one or more types selected from the group consisting of urethane adhesives, acid-modified polyolefin adhesives, polyester adhesives, polyether adhesives, and polyamide adhesives.

[0091] From the viewpoint of further improving the balance of performance between the adhesion between the substrate layer and the easily openable film 50 of this embodiment, heat seal strength, and mechanical strength, the thickness of the adhesive layer is preferably 0.1 μm to 10 μm, more preferably 0.5 μm to 5 μm, and even more preferably 1.0 μm to 3 μm.

[0092] <Package> The packaging of this embodiment preferably includes a lid material and a container, wherein the easy-open film 50 in the lid material is sealed to the container. The lid material of this embodiment has an improved balance of heat seal strength, mechanical strength, and zip-sealing resistance, making it suitable for use as a lid material for packaging.

[0093] In this embodiment, from the viewpoint of improving the balance of heat seal strength, mechanical strength, and zip-sealing performance, the packaging preferably has the seal layer 10 sealed to the container in the easy-open film 50 within the lid material.

[0094] As the container, known containers conventionally used as packaging containers can be used. Among these, from the viewpoint of improving the balance of performance between heat seal strength, mechanical strength and zip suppression, the container preferably contains one or more selected from the group consisting of polyethylene terephthalate such as amorphous polyethylene terephthalate and crystalline polyethylene terephthalate, polystyrene such as unfoamed polystyrene and foamed polystyrene, polyethylene such as unfoamed polyethylene and foamed polyethylene, polypropylene such as unfoamed polypropylene and foamed polypropylene, polyvinyl chloride, polylactic acid and glass, and more preferably contains one or more selected from the group consisting of polyethylene terephthalate, polystyrene, polyethylene and polypropylene.

[0095] The container may take various forms, such as film, sheet, tray, cup, or bottle.

[0096] There are no particular restrictions on the contents of the packaging, but it can be preferably used for packaging food, pharmaceuticals, medical devices, daily necessities, and general merchandise. The balance between the heat seal strength and zip-suppression performance of the easy-open film 50 of this embodiment makes it particularly suitable for use as food packaging.

[0097] The embodiments of the present invention have been described above with reference to the drawings, but these are merely examples of the present invention, and various other configurations can also be adopted. It should be noted that the present invention is not limited to the embodiments described above, and any modifications, improvements, etc., that can achieve the objectives of the present invention are included in the present invention. [Examples]

[0098] The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

[0099] The details of the method for producing the easy-open film are as follows.

[0100] <Raw material ingredients> [Supporting layers (core layer, laminate layer)] • Support layer resin 1: Linear low-density polyethylene (LLDPE, density: 924 kg / m³) 3 Melting point: 120℃, MFR (190℃): 3.8g / 10min) • Support layer resin 2: Linear low-density polyethylene (LLDPE, density: 909 kg / m³) 3 Melting point: 115℃, MFR (190℃): 2.3g / 10min) • Support layer resin 3: High-density polyethylene (HDPE, density: 950 kg / m³) 3 Melting point: 135℃, MFR (190℃): 1.1g / 10min) • Support layer resin 4: Homopolypropylene (hPP, density: 910 kg / m³) 3 Melting point: 162℃, MFR (230℃): 7.0g / 10min) • Slip agent 1: A masterbatch containing 3% by mass of linear low-density polyethylene base and erucic acid amide (erucic acid amide acts as the slip agent).

[0101] [Seal layer] • Seal layer resin 1: Ethylene-vinyl acetate copolymer (Density: 954 kg / m³) 3 MFR (190℃): 17.0g / 10min) • Seal layer resin 2: Ethylene-vinyl acetate copolymer (density: 980 kg / m³) 3 MFR (190℃): 31.0g / 10min) • Incompatible resin 1: Amorphous polyethylene terephthalate (density: 1300 kg / m³) 3 ) • Incompatible resin 2: Amorphous polyethylene terephthalate (density: 1310 kg / m³) 3 ) • Incompatible resin 3: Polystyrene (Density: 1050 kg / m³) 3 MFR (190℃): 7.5g / 10min) • Incompatible resin 4: Adhesive polyolefin (Density: 888 kg / m³) 3 MFR (190℃): 7.2g / 10min) • Incompatible resin 5: α-olefin copolymer (density: 885 kg / m³) 3 MFR (190℃): 3.6g / 10min) • Antiblocking agent 1: A masterbatch consisting of a mixture of erucic acid amide (2 parts by mass), zeolite (20 parts by mass), and ethylene-vinyl acetate copolymer (78 parts by mass) as a base resin.

[0102] The MFR of the raw material components conforms to JIS K7210:1999, at 190°C or 230°C. Measurements were taken under a 2.16 kg load.

[0103] <Preparation of easily peelable films> [Examples 1-12, Comparative Examples 1-2] Each layer was co-extruded using the T-die method with the components, content, and layer thickness shown in Table 1 to form a laminated film consisting of a three-layer co-extruded film with a laminate layer, core layer, and seal layer. Next, the laminate layer was subjected to corona treatment to obtain the easily openable films of each example and comparative example.

[0104] <Rating> The physical properties of the obtained easy-open film were measured using the following method. The results are shown in Table 1. Note that "-" in the table indicates that the measurement was not performed.

[0105] [Young's modulus obtained by nanoindentation method] The Young's modulus was measured for the laminate and seal layers of the easily openable films of each example and comparative example, measuring 1 cm x 1 cm, using the nanoindentation method under the following conditions. • Measuring device: iMicro (manufactured by KLA Corporation) • Measurement mode: Continuous stiffness measurement method (CSM / CSR) • Indenter: Diamond triangular pyramidal indenter (manufactured by Toyo Technica Co., Ltd., product name: InForce50 (high-resolution head)) • Strain rate: 0.2 [1 / s] • Indenter vibration frequency: 110 [Hz] • Indenter vibration amplitude: 2 [nm] Poisson's ratio: 0.35 • Young's modulus calculation depth: 500 [nm]

[0106] [Blocking power] A 15 μm thick nylon film (Toyobo Co., Ltd., product name: N1202) was laminated onto a 12 μm thick biaxially oriented polyethylene terephthalate film (PET film, Toyobo Co., Ltd., product name: E5102) by dry lamination using a urethane adhesive (Mitsui Chemicals, product name: a mixture of Takelac® A-627 and Takenate® A-65). Next, one side of the easy-open film of each example and comparative example was laminated onto the side of the nylon film that was not in contact with the PET film by dry lamination using the urethane adhesive, to prepare a laminated film in which the PET film and the seal layer were the outermost layers. Subsequently, the laminated film was cut to prepare strip-shaped test pieces measuring 20 mm x 100 mm in width. Next, five laminates were prepared by overlapping the seal layers of the test pieces. Then, near the center of the laminate, a 26mm x 76mm glass slide was used to sandwich the laminate between the glass slides so that they were perpendicular to each other. The overlapping area of ​​the laminate and the glass slides was 5.2cm. 2 A load of 4 kg was placed on the area, and the sample was aged at 40°C for 24 hours, then allowed to cool. After cooling, the peel strength between the PET film and the seal layer of the laminate, and the peel strength between the seal layers themselves, were separately evaluated using a universal tensile testing machine (A&D Corporation, product name: RTG-1210) at a crosshead speed of 300 mm / min using the shear peel method, and the maximum strength was calculated. The maximum strength was evaluated for n=5, and the average value was used as the blocking force (N / 5.2cm). 2 )

[0107] [Heat seal strength] A 12 μm thick biaxially oriented polyethylene terephthalate film (PET film, manufactured by Toyobo Co., Ltd., product name: E5102), a 7 μm thick aluminum foil, the 12 μm thick biaxially oriented polyethylene terephthalate film, and the easy-open films of each example and comparative example were laminated in this order using a urethane adhesive (manufactured by Mitsui Chemicals, product name: a mixture of Takelac® A-627 and Takenate® A-65) to obtain a laminate. Here, the biaxially oriented polyethylene terephthalate film was laminated to the laminate layer side of the easy-open films of each example and comparative example using the urethane adhesive. Next, a 400 μm thick polystyrene film (PS), amorphous polyethylene terephthalate film (A-PET), or polypropylene film (PP) was superimposed on the seal layer side of the easily openable film in the laminate. Using a heat sealer, the laminate and the adherend were heat-sealed for 1 second at a temperature of 170°C (PS) or 180°C (A-PET, PP) and a pressure of 0.2 MPa with a 5 mm wide sealing bar, and then allowed to cool. Subsequently, 15 mm wide test pieces were cut from the heat-sealed laminate and adherend, and the adherend was peeled off in a 180-degree direction using a universal tensile testing machine (A&D Co., Ltd., product name: RTG-1210) at a constant temperature of 23°C and 50% RH at a tensile speed of 500 mm / min. The maximum load was measured and the heat seal strength (N / 15 mm) for PS, A-PET, and PP was determined.

[0108] [Tensile modulus of elasticity] A 15 mm x 15 cm test specimen was cut from the easily openable film of each example and comparative example. Then, in accordance with JIS K7127:1999, the tensile modulus T1 (MPa) in the MD direction and the tensile modulus T2 (MPa) in the TD direction of the test specimen were measured using a tensile testing machine (A&D Corporation, product name: RTG-1210) under the conditions of a measurement temperature of 23 ± 2 °C, 50 ± 5% RH, and a tensile speed of 5 mm / min.

[0109] [Zipping rating] A 12 μm thick biaxially oriented polyethylene terephthalate film (PET film, manufactured by Toyobo Co., Ltd., product name: E5102), a 7 μm thick aluminum foil, the 12 μm thick biaxially oriented polyethylene terephthalate film, and the easy-open films of each example and comparative example were laminated in this order using a urethane adhesive (manufactured by Mitsui Chemicals, product name: a mixture of Takelac® A-627 and Takenate® A-65) to obtain a laminate. Here, the biaxially oriented polyethylene terephthalate film was laminated to the laminate layer side of the easy-open films of each example and comparative example using the urethane adhesive. Next, a 400 μm thick amorphous polyethylene terephthalate film (A-PET) was placed on the seal layer side of the easily openable film in the laminate as an adherend. Using a heat sealer, a 10 cm length of the laminate and adherend was heat-sealed for 1 second at a temperature of 180°C and a pressure of 0.2 MPa with a 5 mm wide sealing bar, and then allowed to cool. After that, the heat-sealed laminate and adherend were peeled off in the 5 mm width direction at a peeling speed of 1000 mm / min and a peeling angle of 90° using an adhesive / film peel analysis device (Kyowa Interface Science Co., Ltd., product name: VPN-H200), and the appearance after peeling was checked. Linear peel marks remained on the seal surface of the laminate perpendicular to the peeling direction as zipping marks. The number of linear peel marks in the peeled 10 cm was counted and evaluated as follows. A smaller number indicates lower zipping properties. A: 0 or more and 10 or less B: 11 or more and 80 or less C: 81 or more pieces

[0110] [Table 1]

[0111] Each embodiment, which included a sealing layer and measured the blocking force between the sealing layers within a specific numerical range using a particular method, showed an improved balance between the heat seal strength and zip-suppression performance of the easy-open film. [Explanation of Symbols]

[0112] 10 sealing layers 20 Support layer 21 Core Layers 22 Laminate layer 50 Easy-open film

Claims

1. An easily tamper-evident film having a sealing layer, The blocking force between the sealing layers according to the following (Method 1) is 70 N / 5.2 cm ２ The following is an easy-open film. (Method 1) A 15 μm thick nylon film is laminated onto a 12 μm thick biaxially oriented polyethylene terephthalate film (PET film) by dry lamination using a urethane adhesive. Next, one side of the easy-open film is laminated onto the side of the nylon film that is not in contact with the PET film by dry lamination using a urethane adhesive, preparing a laminated film in which the PET film and the seal layer are the outermost layers. Then, the laminated film is cut to create strip-shaped test pieces measuring 20 mm x 100 mm in width. Next, five laminates are prepared by overlapping the seal layers of the test pieces. Then, near the center of the laminate, the laminate is sandwiched between two 26 mm x 76 mm microscope slides so that the laminate and the microscope slides are at a right angle. The overlapping length of the laminate and the microscope slides is 5.2 cm. ２ A load of 4 kg is placed on the area, and it is aged at 40°C for 24 hours, then allowed to cool. After cooling, the peel strength between the sealing layers of the laminate is evaluated separately using a universal tensile testing machine at a crosshead speed of 300 mm / min using the shear peel method, and the maximum strength is calculated. The maximum strength is evaluated for n=5, and the average value is used as the blocking force (N / 5.2 cm). ２ )

2. The easy-open film according to claim 1, wherein the sealing layer comprises an ethylene-vinyl acetate copolymer.

3. The easy-open film according to claim 2, wherein the content of the ethylene-vinyl acetate copolymer in the sealing layer is 20% by mass or more and 100% by mass or less when the entire sealing layer is considered to be 100% by mass.

4. The easy-open film according to claim 2 or 3, wherein the sealing layer comprises an incompatible resin that is incompatible with the ethylene-vinyl acetate copolymer.

5. The easy-open film according to claim 4, wherein the non-compatible resin comprises one or more selected from the group consisting of polyethylene terephthalate, polystyrene, and polyolefin.

6. The easy-open film according to claim 4 or 5, wherein the content of the incompatible resin in the sealing layer is 1% by mass or more and 70% by mass or less when the entire sealing layer is considered to be 100% by mass.

7. The easy-open film according to any one of claims 1 to 6, wherein the sealing layer contains an antiblocking agent.

8. The easy-open film according to claim 7, wherein the content of the antiblocking agent in the sealing layer is 0.1% by mass or more and 20% by mass or less, when the entire sealing layer is considered to be 100% by mass.

9. The easy-open film according to any one of claims 1 to 8, wherein the thickness of the sealing layer is 1 μm or more and 50 μm or less.

10. An easily openable film according to any one of claims 1 to 9, further comprising a support layer.

11. The easy-open film according to claim 10, wherein the support layer contains a polyolefin.

12. The easy-open film according to claim 11, wherein the polyolefin in the support layer comprises one or more selected from the group consisting of polyethylene and polypropylene.

13. The easy-open film according to any one of claims 10 to 12, wherein the thickness of the support layer is 5 μm or more and 150 μm or less.

14. The easy-open film according to any one of claims 10 to 13, wherein the support layer comprises a core layer and a laminate layer.

15. The easy-open film according to claim 14, wherein the core layer contains polyolefin.

16. The easy-open film according to claim 15, wherein the polyolefin in the core layer comprises one or more selected from the group consisting of polyethylene and polypropylene.

17. The easy-open film according to any one of claims 14 to 16, wherein the thickness of the core layer is 3 μm or more and 100 μm or less.

18. The easy-open film according to any one of claims 14 to 17, wherein the laminate layer contains polyolefin.

19. The easy-open film according to claim 18, wherein the polyolefin in the laminate layer comprises one or more selected from the group consisting of polyethylene and polypropylene.

20. The easy-open film according to any one of claims 14 to 19, wherein the laminate layer further comprises a slip agent.

21. The easy-open film according to claim 20, wherein the content of the slip agent in the laminate layer is 0.01% by mass or more and 2.00% by mass or less, when the entire laminate layer is considered to be 100% by mass.

22. The easy-open film according to any one of claims 14 to 21, wherein the thickness of the laminate layer is 2 μm or more and 50 μm or less.

23. An easily openable film according to any one of claims 1 to 22, which can be used on an adherend containing one or more selected from the group consisting of polyethylene terephthalate, polystyrene, polyethylene, and polypropylene.

24. An easy-open film according to any one of claims 1 to 23, wherein the heat seal strength by the following method (Method 2) is 5 N / 15 mm or more and 50 N / 15 mm or less. (Method 2) A laminate is obtained by bonding a 12 μm thick biaxially oriented polyethylene terephthalate film, a 7 μm thick aluminum foil, a 12 μm thick biaxially oriented polyethylene terephthalate film, and the easy-open film in this order using a urethane adhesive. Next, a 400 μm thick amorphous polyethylene terephthalate sheet (A-PET) is placed on the seal layer side of the easy-open film in the laminate as the adherend, and the laminate and adherend are heat-sealed for 1 second using a heat sealer at a temperature of 180°C and a pressure of 0.2 MPa with a 5 mm wide sealing bar, and then allowed to cool. After that, a 15 mm wide test piece is cut from the heat-sealed laminate and adherend, and the adherend is peeled off in a 180-degree direction using a universal tensile testing machine at a constant temperature of 23°C and 50% RH under the conditions of a tensile speed of 500 mm / min, and the maximum load is measured to determine the heat seal strength (N / 15 mm) for A-PET.

25. The tensile modulus T in the MD direction according to the following (Method 3) １ An easy-to-open film according to any one of claims 1 to 24, wherein the pressure is 10 MPa or more and 2000 MPa or less. (Method 3) A 15 mm x 15 cm test piece is cut from the aforementioned easy-open film. Then, in accordance with JIS K7127:1999, the tensile modulus T in the MD direction of the test piece is measured under the conditions of a measurement temperature of 23 ± 2 °C, 50 ± 5% RH, and a tensile speed of 5 mm / min. １ Measure the pressure (MPa).

26. The tensile modulus T in the TD direction is determined below (Method 4). ２ An easy-to-open film according to any one of claims 1 to 25, wherein the pressure is 10 MPa or more and 2000 MPa or less. (Method 4) A 15 mm x 15 cm test piece is cut from the aforementioned easy-open film. Then, in accordance with JIS K7127:1999, the tensile modulus of elasticity T in the TD direction of the test piece is measured under the conditions of a measurement temperature of 23 ± 2 °C, 50 ± 5% RH, and a tensile speed of 5 mm / min. ２ Measure the pressure (MPa).

27. A lid material comprising an easily openable film according to any one of claims 1 to 26.

28. A lid material comprising, in this order, a base layer, an adhesive layer, and an easy-open film according to any one of claims 1 to 26.

29. A lid material according to claim 27 or 28 and a container, A package in which the easy-open film in the lid material is sealed to the container.

30. The packaging according to claim 29, wherein the container comprises one or more materials selected from the group consisting of polyethylene terephthalate, polystyrene, polyethylene, and polypropylene.

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