Packaging film, packaging material, and packaging

Abstract

A packaging film (100) comprises, in this order: (a) one or more polyethylene films selected from the group consisting of an unstretched polyethylene film and a uniaxially stretched polyethylene film; (b) a biaxially stretched polyethylene film; and (c) one or more polyethylene films selected from the group consisting of an unstretched polyethylene film and a uniaxially stretched polyethylene film.

Description

Packaging films, packaging materials and packages

[0001] The present invention relates to a packaging film, a packaging material, and a package.

[0002] Polyethylene films are used as various packaging materials for foods and beverages, medical supplies and pharmaceuticals, industrial materials, daily necessities, etc. Patent Document 1 describes a method for simultaneously improving the transparency and tear strength of a film mainly made of high-density polyethylene resin, which has a density of 0.94 g / cm. ３ 50 to 80 parts by weight of high-density polyethylene having a melt index of 1 g / 10 min or less, and a density of 0.93 g / cm ３ 10 to 30 parts by weight of a branched low-density polyethylene having a melt index of 3 g / 10 min or less, and a density of 0.93 g / cm ３ The present invention describes a method for producing a transparent film, which is characterized by subjecting a composition containing 10 to 30 parts by weight of linear low-density polyethylene having a melt index of 3 g / 10 min or less to inflation molding under conditions in which the cooling rate index τ, as represented by a specific formula, is 4 or less.

[0003] Japanese Patent Application Publication No. 9-239830

[0004] The present invention provides a packaging film having an improved balance of hand-tearability and heat-sealability.

[0005] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result have found that a packaging film comprising, in this order, one or more polyethylene films (a) selected from the group consisting of unstretched polyethylene films and uniaxially stretched polyethylene films, a biaxially oriented polyethylene film (b), and one or more polyethylene films (c) selected from the group consisting of unstretched polyethylene films and uniaxially stretched polyethylene films can have an improved balance of hand-tearability and heat-sealability, thereby completing the present invention.

[0006] According to the present invention, there are provided the following packaging films, packaging materials, and packaging articles.

[0007] [1] A packaging film comprising, in this order: one or more polyethylene films (a) selected from the group consisting of unstretched polyethylene films and uniaxially stretched polyethylene films; a biaxially stretched polyethylene film (b); and one or more polyethylene films (c) selected from the group consisting of unstretched polyethylene films and uniaxially stretched polyethylene films. [2] The packaging film according to [1], wherein the polyethylene film (a) comprises a uniaxially stretched polyethylene film. [3] The packaging film according to [1] or [2], wherein the polyethylene film (c) comprises a unstretched polyethylene film. [4] The packaging film according to [1] or [2], wherein the density of the polyethylene film (a) is 0.917 g / cm, as measured in accordance with JIS K 7112:1999. ３ 0.970g / cm or more ３ [5] The packaging film according to any one of [1] to [3], wherein the density of the biaxially oriented polyethylene film (b) measured in accordance with JIS K 7112:1999 is 0.917 g / cm or less. ３ 0.970g / cm or more ３[6] The packaging film according to any one of [1] to [5], wherein the thickness of the polyethylene film (a) is 5 μm or more and 50 μm or less. [7] The packaging film according to any one of [1] to [6], wherein the thickness of the biaxially oriented polyethylene film (b) is 5 μm or more and 50 μm or less. [8] The packaging film according to any one of [1] to [7], wherein the thickness of the polyethylene film (c) is 10 μm or more and 200 μm or less. [9] The packaging film according to any one of [1] to [8], wherein the ratio A / B of the thickness A of the polyethylene film (a) to the thickness B of the biaxially oriented polyethylene film (b) is 0.3 or more and 3.0 or less.

[10] The packaging film according to any one of [1] to [9], wherein the ratio C / B of the thickness C of the polyethylene film (c) to the thickness B of the biaxially oriented polyethylene film (b) is 1.1 or more and 10.0 or less.

[11] The packaging film according to any one of [1] to

[10] , further comprising an adhesive layer at least one between the polyethylene film (a) and the biaxially oriented polyethylene film (b) and between the biaxially oriented polyethylene film (b) and the polyethylene film (c).

[12] The packaging film according to any one of [1] to

[11] , wherein the polyethylene film (a) is the outermost layer.

[13] The packaging film according to any one of [1] to

[12] , wherein the polyethylene film (c) is the innermost layer.

[14] The packaging film according to any one of [1] to

[13] , wherein the packaging film has a tensile modulus in the MD direction of 170 MPa to 500 MPa and a tensile modulus in the TD direction of 160 MPa to 600 MPa, as measured in accordance with JIS K7127:1999 using a tensile tester under conditions of a measurement temperature of 23±2°C, 50±5% RH, and a pulling rate of 5 mm / min.

[15] The packaging film according to any one of [1] to

[14] , wherein the stress at break in the MD direction of the packaging film is 20 MPa or more and 50 MPa or less, and the stress at break in the TD direction of the packaging film is 10 MPa or more and 40 MPa or less, as measured using a tensile tester in accordance with JIS K7127:1999 under conditions of a measurement temperature of 23±2°C, 50±5% RH, and a tensile speed of 5 mm / min.

[16] The packaging film according to any one of [1] to

[15] , wherein the packaging film has an MD elongation at break of 50% to 200% and a TD elongation at break of 50% to 200% when measured in accordance with JIS K7127:1999 using a tensile tester at a temperature of 23±2°C, 50±5% RH, and a pulling rate of 5 mm / min.

[17] The packaging film according to any one of [1] to

[16] , wherein the packaging film has an MD lamination strength of 3.0 N / 15 mm or more, measured by Method 1 below. (Method 1) The packaging film is cut into a width of 15 mm and a length of 70 mm to prepare a test piece. Next, the maximum peel strength of the test piece is measured using a Tensilon universal testing machine at a pulling rate of 300 mm / min and a temperature of 23°C, and this value is defined as the lamination strength (N / 15 mm).

[18] The packaging film according to any one of [1] to

[17] , wherein the heat seal strength in the MD direction of the packaging film is 30 N / 15 mm or more and the heat seal strength in the TD direction is 25 N / 15 mm or more, as measured by Method 2 below. (Method 2) The packaging film is cut into a width of 70 mm and a length of 70 mm to prepare two test pieces. Next, the two prepared test pieces are overlapped with the polyethylene film (c) facing each other, and then heat-sealed using a heat seal tester under conditions of an upper temperature (heat seal temperature) of 140°C, a lower temperature of 25°C, a sealing pressure of 0.2 MPa, and a sealing time of 1 second. Next, the heat-sealed test piece is removed and cut to a width of 15 mm. Next, the maximum peel strength of the heat-sealed 15 mm-wide test piece is measured using a Tensilon universal testing machine at a tensile speed of 300 mm / min and a temperature of 23°C, and this is defined as the heat seal strength (N / 15 mm).

[19] The packaging film according to any one of [1] to

[18] , wherein the tear strength in the MD direction of the packaging film is 100 mN or more and 3000 mN or less, and the tear strength in the TD direction is 100 mN or more and 2000 mN or less, measured by the following method 3. (Method 3) The packaging film is cut into a size of 63.5 mm wide x 50 mm long to prepare a test piece.Next, the tear strength (mN) of the test piece is measured using a light-load tear tester under the conditions of a pendulum weight of 720 g, a cut length of 12.7 mm, and a pendulum lift angle of 90°.

[20] A packaging material comprising the packaging film according to any one of [1] to

[19] .

[21] A package comprising the packaging material according to

[20] and an article inside the packaging material, wherein the polyethylene film (a) is on the outer side and the polyethylene film (c) is on the article side.

[0008] According to the present invention, it is possible to provide a packaging film, a packaging material, and a packaged article that have an improved balance of hand-tearability and heat-sealability.

[0009] 1 is a schematic cross-sectional view showing an example of the structure of a packaging film according to an embodiment of the present invention.

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the drawings are for illustrative purposes only. The shapes and dimensional ratios of the components in the drawings do not necessarily correspond to the actual products.

[0011] In this embodiment, "A to B" indicating a numerical range means A or more and B or less unless otherwise specified.

[0012] <Packaging film> Figure 1 is a schematic cross-sectional view showing an example of the structure of a packaging film 100 according to an embodiment of the present invention. The packaging film 100 of this embodiment comprises, in this order, one or more polyethylene films (a) selected from the group consisting of unstretched polyethylene films and uniaxially stretched polyethylene films, a biaxially stretched polyethylene film (b), and one or more polyethylene films (c) selected from the group consisting of unstretched polyethylene films and uniaxially stretched polyethylene films.

[0013]

[0009] The present inventors have found that a multilayer film comprising one or more polyethylene films selected from the group consisting of non-stretched polyethylene films and uniaxially stretched polyethylene films on both sides of a biaxially stretched polyethylene film has a better balance of hand-tearability and heat-sealability than a multilayer film comprising one or more polyethylene films selected from the group consisting of non-stretched polyethylene films and uniaxially stretched polyethylene films on only one side of a biaxially stretched polyethylene film. Based on this finding, the present inventors have conducted further studies and found that a packaging film 100 comprising, in this order, one or more polyethylene films (a) selected from the group consisting of non-stretched polyethylene films and uniaxially stretched polyethylene films, a biaxially stretched polyethylene film (b), and one or more polyethylene films (c) selected from the group consisting of non-stretched polyethylene films and uniaxially stretched polyethylene films can have an improved balance of hand-tearability and heat-sealability, thereby completing the present invention.

[0014] In the packaging film 100 of this embodiment, from the viewpoint of further improving the balance of performance among hand-tearability, heat-sealability, twistability, impact resistance, transparency, and sealability, the polyethylene film (a) preferably comprises a uniaxially stretched polyethylene film. In the packaging film 100 of this embodiment, from the viewpoint of further improving the balance of performance among hand-tearability, heat-sealability, cost, and dimensional stability, the polyethylene film (c) preferably comprises a non-stretched polyethylene film. In the packaging film 100 of this embodiment, from the viewpoint of further improving the balance of performance among hand-tearability, heat-sealability, twistability, impact resistance, transparency, sealability, and dimensional stability, it is more preferable that the polyethylene film (a) comprises a uniaxially stretched polyethylene film and the polyethylene film (c) comprises a non-stretched polyethylene film.

[0015] In the packaging film 100 of this embodiment, the density of the polyethylene film (a) measured in accordance with JIS K 7112:1999 is preferably 0.917 g / cm from the viewpoint of further improving the balance of performance among hand tearability, heat sealability, rigidity, heat resistance, and impact resistance. ３ More preferably, 0.920 g / cm ３ More preferably, 0.923 g / cm ３ More preferably, 0.926 g / cm ３ More preferably, 0.929 g / cm ３ More preferably, 0.932 g / cm ３ More preferably, 0.935 g / cm ３ More preferably, 0.938 g / cm ３ and preferably 0.970 g / cm ３ or less, more preferably 0.965 g / cm ３ More preferably, 0.960 g / cm ３ More preferably, 0.955 g / cm or less ３ More preferably, 0.950 g / cm or less ３ More preferably, 0.946 g / cm or less ３ More preferably, 0.943 g / cm or less ３ The following is the result.

[0016] In the packaging film 100 of this embodiment, the density of the biaxially oriented polyethylene film (b), measured in accordance with JIS K 7112:1999, is preferably 0.917 g / cm from the viewpoint of further improving the balance of performance among hand-tearability, heat-sealability, heat resistance, impact resistance, flexibility, moldability, and transparency. ３ More preferably, 0.920 g / cm ３ More preferably, 0.923 g / cm ３ More preferably, 0.926 g / cm ３ More preferably, 0.928 g / cm ３ and preferably 0.970 g / cm ３ or less, more preferably 0.960 g / cm ３More preferably, 0.955 g / cm or less ３ More preferably, 0.950 g / cm or less ３ More preferably, 0.945 g / cm or less ３ More preferably, 0.940 g / cm ３ More preferably, 0.936 g / cm or less ３ More preferably, 0.933 g / cm or less ３ The following is the result.

[0017] In the packaging film 100 of this embodiment, the density of the polyethylene film (c) measured in accordance with JIS K 7112:1999 is preferably 0.870 g / cm from the viewpoint of further improving the balance of performance among hand-tearability, heat-sealability, flexibility, moldability, and transparency. ３ More preferably, 0.880 g / cm ３ More preferably, 0.890 g / cm ３ More preferably, 0.900 g / cm ３ More preferably, 0.905 g / cm ３ More preferably, 0.910 g / cm ３ More preferably, 0.913 g / cm ３ More preferably, 0.916 g / cm ３ and preferably 0.930 g / cm ３ or less, more preferably 0.926 g / cm ３ More preferably, 0.923 g / cm or less ３ More preferably, 0.920 g / cm ３ The following is the result.

[0018] In the packaging film 100 of this embodiment, the thickness of the polyethylene film (a) is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, from the viewpoint of further improving the performance balance of hand-tearability, heat-sealability, film-forming ability, sealability, cost, impact resistance, bag-forming ability, light weight, and transparency, and is preferably 50 μm or less, more preferably 40 μm or less, even more preferably 35 μm or less, even more preferably 30 μm or less.

[0019] In the packaging film 100 of this embodiment, the thickness of the biaxially oriented polyethylene film (b) is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, and even more preferably 20 μm or more, from the viewpoint of further improving the performance balance of hand-tearability, heat-sealability, film-forming ability, sealability, cost, impact resistance, bag-forming ability, light weight, and transparency, and is preferably 50 μm or less, more preferably 45 μm or less, even more preferably 40 μm or less, and even more preferably 35 μm or less.

[0020] In the packaging film 100 of this embodiment, the thickness of the polyethylene film (c) is, from the viewpoint of further improving the balance of performance among hand-tearability, heat-sealability, film-forming ability, sealability, cost, impact resistance, bag-forming ability, light weight, and transparency, preferably 10 μm or more, more preferably 30 μm or more, even more preferably 40 μm or more, even more preferably 50 μm or more, even more preferably 55 μm or more, and even more preferably 60 μm or more, and is preferably 200 μm or less, more preferably 170 μm or less, even more preferably 150 μm or less, even more preferably 140 μm or less, even more preferably 130 μm or less, even more preferably 120 μm or less, and even more preferably 110 μm or less.

[0021] In the packaging film 100 of this embodiment, the ratio A / B of the thickness A of the polyethylene film (a) to the thickness B of the biaxially oriented polyethylene film (b) is, from the viewpoint of further improving the balance of performance among hand-tearability, heat-sealability, film-formability, sealability, cost, impact resistance, bag-formability, light weight, and transparency, preferably 0.3 or more, more preferably 0.4 or more, even more preferably 0.5 or more, and still more preferably 0.6 or more, and is preferably 3.0 or less, more preferably 2.5 or less, even more preferably 2.0 or less, even more preferably 1.7 or less, even more preferably 1.4 or less, and still more preferably 1.2 or less.

[0022] In the packaging film 100 of this embodiment, the ratio C / B of the thickness C of the polyethylene film (c) to the thickness B of the biaxially oriented polyethylene film (b) is, from the viewpoint of further improving the balance of performance among hand-tearability, heat-sealability, film-formability, sealability, cost, impact resistance, bag-formability, light weight, and transparency, preferably 1.1 or more, more preferably 1.5 or more, even more preferably 1.8 or more, even more preferably 2.0 or more, and still more preferably 2.2 or more, and is preferably 10.0 or less, more preferably 8.0 or less, even more preferably 7.0 or less, even more preferably 6.0 or less, even more preferably 5.0 or less, and still more preferably 4.5 or less.

[0023] From the viewpoint of further improving the balance of performance among hand tearability, heat sealability, film-forming ability, sealability, cost, impact resistance, bag-forming ability, light weight, and transparency, the thickness of the packaging film 100 of this embodiment is preferably 20 μm or more, more preferably 50 μm or more, even more preferably 70 μm or more, even more preferably 90 μm or more, even more preferably 100 μm or more, even more preferably 110 μm or more, and even more preferably 120 μm or more, and is preferably 300 μm or less, more preferably 250 μm or less, even more preferably 220 μm or less, even more preferably 200 μm or less, even more preferably 180 μm or less, even more preferably 170 μm or less, and even more preferably 160 μm or less.

[0024] From the viewpoint of further improving the balance of performance among hand-tearability, heat-sealability, film-forming ability, and laminate strength, the packaging film 100 of this embodiment preferably further includes an adhesive layer 110 between the polyethylene film (a) and the biaxially oriented polyethylene film (b) and between the biaxially oriented polyethylene film (b) and the polyethylene film (c), and more preferably includes an adhesive layer 110 in both.

[0025] When the packaging film 100 of this embodiment includes the adhesive layer 110, the thickness of the adhesive layer 110 is, from the viewpoint of further improving the performance balance of hand tearability, heat sealability, film-forming ability, and lamination strength, preferably 0.1 μm or more, more preferably 0.5 μm or more, even more preferably 1.0 μm or more, even more preferably 1.5 μm or more, even more preferably 2.0 μm or more, and even more preferably 2.5 μm or more, and is preferably 10.0 μm or less, more preferably 8.0 μm or less, even more preferably 6.0 μm or less, even more preferably 5.0 μm or less, even more preferably 4.0 μm or less, and even more preferably 3.5 μm or less.

[0026] When the packaging film 100 of this embodiment includes the adhesive layer 110, the adhesive layer 110 preferably includes one or more adhesives selected from the group consisting of urethane-based adhesives, acid-modified polyolefin-based adhesives, polyester-based adhesives, polyether-based adhesives, and polyamide-based adhesives, from the viewpoint of further improving the performance balance of hand tearability, heat-sealability, film-forming ability, and laminate strength, and more preferably includes a polyester-based adhesive.

[0027] In the packaging film 100 of this embodiment, the polyethylene film (a) is preferably the outermost layer from the viewpoint of further improving the balance of hand-tearability and heat-sealability.

[0028] In the packaging film 100 of this embodiment, the polyethylene film (c) is preferably the innermost layer from the viewpoint of further improving the balance of hand-tearability and heat-sealability.

[0029] For these reasons, the packaging film 100 of this embodiment preferably comprises polyethylene film (a), biaxially oriented polyethylene film (b), and polyethylene film (c) in this order, with polyethylene film (a) as the outermost layer and polyethylene film (c) as the innermost layer, more preferably a layer structure of polyethylene film (a) / biaxially oriented polyethylene film (b) / polyethylene film (c), and even more preferably a layer structure of polyethylene film (a) / adhesive layer 110 / biaxially oriented polyethylene film (b) / adhesive layer 110 / polyethylene film (c).

[0030] <Physical Properties> Preferred physical properties of the packaging film 100 of this embodiment will be described below.

[0031] The tensile modulus of elasticity in the MD direction of the packaging film 100 of this embodiment, measured in accordance with JIS K7127:1999 using a tensile tester under conditions of a measurement temperature of 23±2°C, 50±5% RH, and a tensile speed of 5 mm / min, is preferably 170 MPa or more, more preferably 200 MPa or more, even more preferably 230 MPa or more, even more preferably 260 MPa or more, even more preferably 290 MPa or more, even more preferably 320 MPa or more, and even more preferably 340 MPa or more, from the viewpoint of further improving the performance balance of hand-tearability, heat-sealability, and impact resistance, and is preferably 500 MPa or less, more preferably 470 MPa or less, even more preferably 440 MPa or less, even more preferably 410 MPa or less, even more preferably 380 MPa or less, and even more preferably 360 MPa or less.

[0032] The tensile modulus of elasticity in the TD direction of the packaging film 100 of this embodiment, measured in accordance with JIS K7127:1999 using a tensile tester under conditions of a measurement temperature of 23±2°C, 50±5% RH, and a tensile speed of 5 mm / min, is preferably 160 MPa or more, more preferably 200 MPa or more, even more preferably 240 MPa or more, even more preferably 280 MPa or more, even more preferably 310 MPa or more, even more preferably 340 MPa or more, and even more preferably 370 MPa or more, from the viewpoint of further improving the performance balance of hand-tearability, heat-sealability, and impact resistance, and is preferably 600 MPa or less, more preferably 560 MPa or less, even more preferably 520 MPa or less, even more preferably 480 MPa or less, even more preferably 450 MPa or less, and even more preferably 420 MPa or less.

[0033] The total value of the tensile modulus in the MD direction and the tensile modulus in the TD direction of the packaging film 100 of this embodiment, measured in accordance with JIS K7127:1999 using a tensile tester under conditions of a measurement temperature of 23±2°C, 50±5% RH, and a pulling rate of 5 mm / min, is preferably 330 MPa or more, more preferably 400 MPa or more, even more preferably 450 MPa or more, even more preferably 500 MPa or more, even more preferably 550 MPa or more, even more preferably 600 MPa or more, even more preferably 650 MPa or more, and even more preferably 700 MPa or more, and is preferably 1100 MPa or less, more preferably 1000 MPa or less, even more preferably 950 MPa or less, even more preferably 900 MPa or less, even more preferably 850 MPa or less, even more preferably 800 MPa or less, and even more preferably 770 MPa or less, from the viewpoint of further improving the performance balance of hand-tearability, heat-sealability, and impact resistance.

[0034] The MD stress at break of the packaging film 100 of this embodiment, measured in accordance with JIS K7127:1999 using a tensile tester under conditions of a measurement temperature of 23±2°C, 50±5% RH, and a tensile speed of 5 mm / min, is preferably 20 MPa or more, more preferably 23 MPa or more, even more preferably 25 MPa or more, even more preferably 27 MPa or more, and even more preferably 30 MPa or more, from the viewpoint of further improving the performance balance of hand-tearability, heat-sealability, and impact resistance, and is preferably 50 MPa or less, more preferably 45 MPa or less, even more preferably 43 MPa or less, even more preferably 40 MPa or less, and even more preferably 38 MPa or less.

[0035] The stress at break in the TD direction of the packaging film 100 of this embodiment, measured in accordance with JIS K7127:1999 using a tensile tester under conditions of a measurement temperature of 23±2°C, 50±5% RH, and a tensile speed of 5 mm / min, is preferably 10 MPa or more, more preferably 13 MPa or more, even more preferably 15 MPa or more, and still more preferably 18 MPa or more, from the viewpoint of further improving the performance balance of hand-tearability, heat-sealability, and impact resistance, and is preferably 40 MPa or less, more preferably 35 MPa or less, even more preferably 33 MPa or less, even more preferably 30 MPa or less, and still more preferably 28 MPa or less.

[0036] The total value of the stress at break in the MD direction and the stress at break in the TD direction of the packaging film 100 of this embodiment, measured in accordance with JIS K7127:1999 using a tensile tester under conditions of a measurement temperature of 23±2°C, 50±5% RH, and a tensile speed of 5 mm / min, is preferably 30 MPa or more, more preferably 35 MPa or more, even more preferably 38 MPa or more, even more preferably 40 MPa or more, even more preferably 45 MPa or more, even more preferably 47 MPa or more, and even more preferably 50 MPa or more, from the viewpoint of further improving the performance balance of hand-tearability, heat-sealability, and impact resistance, and is preferably 90 MPa or less, more preferably 85 MPa or less, even more preferably 80 MPa or less, even more preferably 75 MPa or less, even more preferably 70 MPa or less, and even more preferably 65 MPa or less.

[0037] The elongation at break in the MD direction of the packaging film 100 of this embodiment, measured in accordance with JIS K7127:1999 using a tensile tester under conditions of a measurement temperature of 23±2°C, 50±5% RH, and a tensile speed of 5 mm / min, is preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, even more preferably 90% or more, even more preferably 95% or more, even more preferably 100% or more, even more preferably 105% or more, and even more preferably 110% or more, from the viewpoint of further improving the performance balance of hand-tearability, heat-sealability, heat resistance, and impact resistance, and is preferably 200% or less, more preferably 180% or less, even more preferably 160% or less, even more preferably 150% or less, even more preferably 140% or less, even more preferably 135% or less, even more preferably 130% or less, and even more preferably 125% or less.

[0038] The elongation at break in the TD direction of the packaging film 100 of this embodiment, measured in accordance with JIS K7127:1999 using a tensile tester under conditions of a measurement temperature of 23±2°C, 50±5% RH, and a tensile speed of 5 mm / min, is preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, even more preferably 90% or more, even more preferably 100% or more, even more preferably 105% or more, even more preferably 110% or more, and even more preferably 115% or more, from the viewpoint of further improving the performance balance of hand-tearability, heat-sealability, heat resistance, and impact resistance, and is preferably 200% or less, more preferably 180% or less, even more preferably 170% or less, even more preferably 160% or less, even more preferably 155% or less, even more preferably 150% or less, even more preferably 145% or less, and even more preferably 140% or less.

[0039] The packaging film 100 of this embodiment is JIS The total value of the MD and TD elongations at break, measured using a tensile tester in accordance with K7127:1999 under conditions of a measurement temperature of 23±2°C, 50±5% RH, and a tensile speed of 5 mm / min, is preferably 100% or more, more preferably 130% or more, even more preferably 150% or more, even more preferably 170% or more, even more preferably 190% or more, even more preferably 200% or more, even more preferably 210% or more, even more preferably 220% or more, even more preferably 225% or more, and is preferably 400% or less, more preferably 370% or less, even more preferably 350% or less, even more preferably 330% or less, even more preferably 310% or less, even more preferably 300% or less, even more preferably 290% or less, even more preferably 280% or less, even more preferably 270% or less, and even more preferably 260% or less, from the viewpoint of further improving the performance balance of hand-tearability, heat-sealability, heat resistance, and impact resistance.

[0040] From the viewpoint of further improving the balance of hand tearability, heat sealability, and impact resistance, the MD lamination strength of the packaging film 100 of this embodiment, measured by Method 1 below, is preferably 3.0 N / 15 mm or more, more preferably 4.0 N / 15 mm or more, even more preferably 5.0 N / 15 mm or more, even more preferably 6.0 N / 15 mm or more, even more preferably 7.0 N / 15 mm or more, even more preferably 8.0 N / 15 mm or more, and even more preferably 9.0 N / 15 mm or more. The upper limit of the MD lamination strength of the packaging film 100 of this embodiment is not particularly limited, and may be, for example, 30.0 N / 15 mm or less, 25.0 N / 15 mm or less, 20.0 N / 15 mm or less, 15.0 N / 15 mm or less, or 12.0 N / 15 mm or less. (Method 1) A packaging film is cut into a test piece having a width of 15 mm and a length of 70 mm. The maximum peel strength of the test piece is then measured using a Tensilon universal testing machine at a tensile speed of 300 mm / min and a temperature of 23°C, and this value is taken as the lamination strength (N / 15 mm).

[0041] From the viewpoint of further improving heat sealability, the heat seal strength in the MD direction of the packaging film 100 of this embodiment, measured by Method 2 below, is preferably 30 N / 15 mm or more, more preferably 35 N / 15 mm or more, even more preferably 40 N / 15 mm or more, even more preferably 45 N / 15 mm or more, even more preferably 50 N / 15 mm or more, even more preferably 55 N / 15 mm or more, and even more preferably 60 N / 15 mm or more. The upper limit of the heat seal strength in the MD direction of the packaging film 100 of this embodiment is not particularly limited, but may be, for example, 150 N / 15 mm or less, 120 N / 15 mm or less, 100 N / 15 mm or less, 90 N / 15 mm or less, or 80 N / 15 mm or less. (Method 2) Two test pieces, each measuring 70 mm wide and 70 mm long, are prepared by cutting the packaging film. Next, the two prepared test pieces are overlapped with the polyethylene film (c) facing each other, and then heat-sealed using a heat seal tester under conditions of an upper temperature (heat seal temperature) of 140°C, a lower temperature of 25°C, a sealing pressure of 0.2 MPa, and a sealing time of 1 second. The heat-sealed test piece is then removed and cut to a width of 15 mm. Next, the maximum peel strength of the heat-sealed 15 mm wide test piece is measured using a Tensilon universal testing machine at a tensile speed of 300 mm / min and a temperature of 23°C, and this is taken as the heat seal strength (N / 15 mm).

[0042] From the viewpoint of further improving heat sealability, the heat seal strength of the packaging film 100 of this embodiment in the TD direction by the above method 2 is preferably 25 N / 15 mm or more, more preferably 30 N / 15 mm or more, even more preferably 35 N / 15 mm or more, even more preferably 40 N / 15 mm or more, and even more preferably 45 N / 15 mm or more. The upper limit of the heat seal strength of the packaging film 100 of this embodiment in the TD direction is not particularly limited, but may be, for example, 100 N / 15 mm or less, 80 N / 15 mm or less, 70 N / 15 mm or less, or 60 N / 15 mm or less.

[0043] From the viewpoint of further improving heat sealability, the total value of the heat seal strength in the MD direction and the heat seal strength in the TD direction of the packaging film 100 of this embodiment, measured by the above method 2, is preferably 55 N / 15 mm or more, more preferably 70 N / 15 mm or more, even more preferably 80 N / 15 mm or more, even more preferably 90 N / 15 mm or more, even more preferably 100 N / 15 mm or more, even more preferably 105 N / 15 mm or more, and even more preferably 110 N / 15 mm or more. The upper limit of the total value of the heat seal strength in the MD direction and the heat seal strength in the TD direction of the packaging film 100 of this embodiment is not particularly limited, and may be, for example, 250 N / 15 mm or less, 200 N / 15 mm or less, 170 N / 15 mm or less, 150 N / 15 mm or less, or 130 N / 15 mm or less.

[0044] From the viewpoint of further improving the balance between hand-tearability and impact resistance, the MD tear strength of the packaging film 100 of this embodiment, as measured by Method 3 below, is preferably 100 mN or more, more preferably 300 mN or more, even more preferably 500 mN or more, even more preferably 600 mN or more, even more preferably 700 mN or more, and even more preferably 800 mN or more, and is preferably 3000 mN or less, more preferably 2500 mN or less, even more preferably 2000 mN or less, even more preferably 1700 mN or less, even more preferably 1500 mN or less, even more preferably 1300 mN or less, even more preferably 1200 mN or less, and even more preferably 1100 mN or less. When the MD tear strength of the packaging film 100 of this embodiment is equal to or greater than the above-mentioned lower limit, impact resistance is improved, and when it is equal to or less than the above-mentioned upper limit, hand-tearability is improved. (Method 3) The packaging film is cut into a 63.5 mm wide x 50 mm long specimen. Next, the tear strength (mN) of the test piece is measured using a light-load tear tester under the conditions of a pendulum weight of 720 g, a cut length of 12.7 mm, and a pendulum lift angle of 90°.

[0045] From the viewpoint of further improving the balance between hand-tearability and impact resistance, the TD tear strength of the packaging film 100 of this embodiment, measured by Method 3, is preferably 100 mN or more, more preferably 300 mN or more, even more preferably 500 mN or more, even more preferably 700 mN or more, even more preferably 800 mN or more, even more preferably 900 mN or more, and even more preferably 950 mN or more, and is preferably 2000 mN or less, more preferably 1800 mN or less, even more preferably 1600 mN or less, even more preferably 1500 mN or less, even more preferably 1400 mN or less, and even more preferably 1300 mN or less. When the TD tear strength of the packaging film 100 of this embodiment is equal to or greater than the lower limit, impact resistance is improved, and when it is equal to or less than the upper limit, hand-tearability is improved.

[0046] From the viewpoint of further improving the performance balance between hand tearability and impact resistance, the total value of the MD tear strength and TD tear strength of the packaging film 100 of this embodiment, measured by the above method 3, is preferably 200 mN or more, more preferably 500 mN or more, even more preferably 800 mN or more, even more preferably 1100 mN or more, even more preferably 1400 mN or more, even more preferably 1600 mN or more, even more preferably 1800 mN or more, and is preferably 5000 mN or less, more preferably 4500 mN or less, even more preferably 4000 mN or less, even more preferably 3500 mN or less, even more preferably 3000 mN or less, even more preferably 2700 mN or less, even more preferably 2500 mN or less, and even more preferably 2300 mN or less. When the total value of the MD tear strength and TD tear strength of the packaging film 100 of this embodiment is equal to or greater than the above-mentioned lower limit, the impact resistance is improved, and when it is equal to or less than the above-mentioned upper limit, the hand tearability is improved.

[0047] <Method for manufacturing packaging film> The packaging film 100 of this embodiment can be obtained, for example, by laminating a polyethylene film (a) and a biaxially oriented polyethylene film (b), and then further laminating a polyethylene film (c) on the side of the biaxially oriented polyethylene film (b). Methods for laminating the polyethylene film (a), biaxially oriented polyethylene film (b), and polyethylene film (c) include, for example, dry lamination, solventless lamination, and extrusion lamination, with dry lamination being preferred. Laminating each layer by dry lamination allows the polyethylene film (a), biaxially oriented polyethylene film (b), and polyethylene film (c) to be laminated while maintaining the performance of each layer.

[0048] As the adhesive used for dry lamination, from the viewpoint of further improving the balance of performance among hand tearability, heat sealability, film-forming ability, and laminate strength, it is preferable to use one or more adhesives selected from the group consisting of urethane-based adhesives, acid-modified polyolefin-based adhesives, polyester-based adhesives, polyether-based adhesives, and polyamide-based adhesives, and it is more preferable to use a polyester-based adhesive.

[0049] When the polyethylene film (a), the biaxially oriented polyethylene film (b), and the polyethylene film (c) are laminated by dry lamination, it is preferable to perform corona treatment on at least the surface of the polyethylene film (a) that will be bonded to another layer and on both surfaces of the biaxially oriented polyethylene film (b) before dry lamination, which improves the adhesion between the layers and increases the laminate strength of the packaging film 100.

[0050] When the polyethylene film (a), the biaxially oriented polyethylene film (b), and the polyethylene film (c) are laminated by dry lamination, it is preferable to perform aging after dry lamination to sufficiently harden the adhesive. From the viewpoint of further improving the laminate strength, the aging temperature is preferably 20°C or higher, more preferably 30°C or higher, even more preferably 35°C or higher, and preferably 60°C or lower, more preferably 50°C or lower, and even more preferably 45°C or lower. From the viewpoint of further improving the laminate strength, the aging time is preferably 20 hours or higher, more preferably 30 hours or higher, even more preferably 40 hours or higher, and preferably 90 hours or lower, more preferably 70 hours or lower, and even more preferably 60 hours or lower.

[0051] <Polyethylene film (a)> From the viewpoint of further improving the balance of performance among hand-tearability, heat-sealability, heat resistance, and impact resistance, the polyethylene film (a) of the present embodiment preferably comprises a high-density polyethylene layer and a linear low-density polyethylene layer, and more preferably comprises a high-density polyethylene layer 1, a linear low-density polyethylene layer, and a high-density polyethylene layer 2, in this order.

[0052] In the polyethylene film (a) of the present embodiment, the total amount of the high-density polyethylene layer 1 and the high-density polyethylene layer 2, relative to the entire polyethylene film (a), is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 25% by mass or more, still more preferably 30% by mass or more, even more preferably 35% by mass or more, still more preferably 40% by mass or more, and still more preferably 45% by mass or more, from the viewpoint of further improving the performance balance of transparency, rigidity, heat resistance, and slip property; and from the viewpoint of incorporating an appropriate amount of the linear low-density polyethylene layer and further improving the laminate strength, the total amount is preferably 85% by mass or less, more preferably 80% by mass or less, even more preferably 75% by mass or less, even more preferably 70% by mass or less, still more preferably 65% ​​by mass or less, even more preferably 60% by mass or less, and still more preferably 55% by mass or less.

[0053] In the polyethylene film (a) of the present embodiment, the high-density polyethylene layer 1 and the high-density polyethylene layer 2 may be formed using the same material or different materials. However, when different materials are used, it is preferable that the high-density polyethylene layer 1 and the high-density polyethylene layer 2 satisfy the following configuration.

[0054] From the viewpoint of further improving the balance of transparency, rigidity, heat resistance, and slip property, the content of high-density polyethylene in high-density polyethylene layer 1 and high-density polyethylene layer 2 is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and still more preferably 98% by mass or more, based on the total content of high-density polyethylene layer 1 and high-density polyethylene layer 2. There is no upper limit to the content of high-density polyethylene in high-density polyethylene layer 1 and high-density polyethylene layer 2, but it is, for example, 100% by mass or less.

[0055] The density of the high-density polyethylene layer 1 and the high-density polyethylene layer 2, measured in accordance with JIS K 7112:1999, is preferably 0.940 g / cm3, from the viewpoint of achieving a better balance of heat resistance, transparency, mechanical properties, and rigidity. ３ More preferably, 0.943 g / cm ３ More preferably, 0.945 g / cm ３ From the viewpoint of achieving a better balance between laminate strength and film formability, it is preferably 0.970 g / cm ３ or less, more preferably 0.968 g / cm ３ More preferably, 0.965 g / cm or less ３ More preferably, 0.960 g / cm ３ More preferably, 0.955 g / cm or less ３ More preferably, 0.950 g / cm or less ３ The following is the result.

[0056] The density of the high-density polyethylene constituting the high-density polyethylene layer 1 and the high-density polyethylene layer 2, as measured in accordance with JIS K 7112:1999, is preferably 0.940 g / cm3, from the viewpoint of achieving a better balance of heat resistance, transparency, mechanical properties, and rigidity. ３ More preferably, 0.943 g / cm ３ More preferably, 0.945 g / cm ３ From the viewpoint of achieving a better balance between laminate strength and film formability, it is preferably 0.970 g / cm ３ or less, more preferably 0.968 g / cm ３ More preferably, 0.965 g / cm or less ３ More preferably, 0.960 g / cm ３ More preferably, 0.955 g / cm or less ３ More preferably, 0.950 g / cm or less ３ The following is the result.

[0057] The melt flow rates (MFR) of the high-density polyethylene layer 1 and the high-density polyethylene layer 2, measured in accordance with ASTM D1238 under conditions of 190°C and a load of 2.16 kg, are each preferably 0.01 g / 10 min or more, more preferably 0.1 g / 10 min or more, even more preferably 0.5 g / 10 min or more, and still more preferably 1.0 g / 10 min or more, from the viewpoint of further improving the balance between fluidity and moldability; and are each preferably 20 g / 10 min or less, more preferably 10 g / 10 min or less, even more preferably 5 g / 10 min or less, even more preferably 3 g / 10 min or less, and still more preferably 2 g / 10 min or less, from the viewpoint of improving the stiffness of the polyethylene film (a) while maintaining the hand-tearability of the polyethylene film (a). The melting points of the high-density polyethylene layer 1 and the high-density polyethylene layer 2, as measured by a differential scanning calorimeter (DSC), are each preferably 120°C or higher, more preferably 125°C or higher, and preferably 135°C or lower, from the viewpoint of further improving the balance of performance such as thermal dimensional stability, heat resistance, mechanical properties, rigidity, bag-formability, flowability, and moldability.

[0058] The melt flow rate (MFR) of the high-density polyethylene constituting the high-density polyethylene layer 1 and the high-density polyethylene layer 2, measured in accordance with ASTM D1238 under conditions of 190°C and a load of 2.16 kg, is preferably 0.01 g / 10 min or more, more preferably 0.1 g / 10 min or more, even more preferably 0.5 g / 10 min or more, and still more preferably 1.0 g / 10 min or more, from the viewpoint of further improving the balance of fluidity and moldability; and from the viewpoint of improving the stiffness of the polyethylene film (a) while maintaining the hand-tearability of the polyethylene film (a), is preferably 20 g / 10 min or less, more preferably 10 g / 10 min or less, even more preferably 5 g / 10 min or less, even more preferably 3 g / 10 min or less, and still more preferably 2 g / 10 min or less, from the viewpoint of improving the stiffness of the polyethylene film (a). The melting points of the high-density polyethylenes constituting the high-density polyethylene layer 1 and the high-density polyethylene layer 2, as measured by a differential scanning calorimeter (DSC), are preferably 120°C or higher, more preferably 125°C or higher, and preferably 135°C or lower, from the viewpoint of further improving the balance of performance such as thermal dimensional stability, heat resistance, mechanical properties, rigidity, bag-formability, flowability, and moldability.

[0059] When two or more types of polyethylene are used as the polyethylene constituting the high-density polyethylene layer, the density, MFR, and melting point of the high-density polyethylene layer can be measured values ​​for a mixture obtained by melt-blending two or more types of polyethylene by a known method. The melting point of the high-density polyethylene layer can be the peak temperature of the maximum melting peak.

[0060] From the viewpoint of suppressing oriented crystallization of the surface layer of the polyethylene film (a) and further improving the laminate strength, the content of the linear low-density polyethylene in the linear low-density polyethylene layer is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and still more preferably 98% by mass or more, based on the entire linear low-density polyethylene layer. There is no upper limit to the content of the linear low-density polyethylene in the linear low-density polyethylene layer, but it is, for example, 100% by mass or less.

[0061] The density of the linear low-density polyethylene layer, measured in accordance with JIS K 7112:1999, is preferably 0.910 g / cm3 from the viewpoint of further improving the balance of mechanical properties, rigidity, and flexibility. ３ More preferably, 0.915 g / cm ３ More preferably, 0.920 g / cm ３ More preferably, 0.925 g / cm ３ From the viewpoint of further improving the balance of laminate strength and flexibility, it is preferably 0.940 g / cm ３ less than 0.933 g / cm ３ More preferably, 0.930 g / cm or less ３ The following is the result.

[0062] The density of the linear low-density polyethylene constituting the linear low-density polyethylene layer, measured in accordance with JIS K 7112:1999, is preferably 0.910 g / cm3 from the viewpoint of further improving the performance balance of mechanical properties, rigidity, and flexibility. ３ More preferably, 0.915 g / cm ３ More preferably, 0.920 g / cm ３ More preferably, 0.925 g / cm ３ From the viewpoint of further improving the balance of laminate strength and flexibility, it is preferably 0.940 g / cm ３ less than 0.933 g / cm ３ More preferably, 0.930 g / cm or less ３ The following is the result.

[0063] The melt flow rate (MFR) of the linear low-density polyethylene layer, measured in accordance with ASTM D1238 under conditions of 190°C and a load of 2.16 kg, is preferably 0.01 g / 10 min or more, more preferably 0.1 g / 10 min or more, even more preferably 0.5 g / 10 min or more, and still more preferably 1.0 g / 10 min or more, from the viewpoint of further improving processability; and from the viewpoint of improving the stiffness of the polyethylene film (a) while maintaining the hand-tearability of the polyethylene film (a), is preferably 20 g / 10 min or less, more preferably 10 g / 10 min or less, even more preferably 5 g / 10 min or less, even more preferably 3 g / 10 min or less, and still more preferably 2 g / 10 min or less. The melting point of the linear low-density polyethylene layer, as measured by a differential scanning calorimeter (DSC), is preferably 120°C or higher, more preferably 125°C or higher, from the viewpoint of improving heat resistance and stiffness while maintaining processability and adhesiveness, and is preferably 135°C or lower, more preferably 130°C or lower, from the viewpoint of improving adhesiveness while maintaining heat resistance.

[0064] The melt flow rate (MFR) of the linear low-density polyethylene constituting the linear low-density polyethylene layer, measured in accordance with ASTM D1238 under conditions of 190°C and a load of 2.16 kg, is preferably 0.01 g / 10 min or more, more preferably 0.1 g / 10 min or more, even more preferably 0.5 g / 10 min or more, and still more preferably 1.0 g / 10 min or more, from the viewpoint of further improving processability; and from the viewpoint of improving the stiffness of the polyethylene film (a) while maintaining the hand-tearability of the polyethylene film (a), is preferably 20 g / 10 min or less, more preferably 10 g / 10 min or less, even more preferably 5 g / 10 min or less, even more preferably 3 g / 10 min or less, and still more preferably 2 g / 10 min or less. The melting point of the linear low-density polyethylene constituting the linear low-density polyethylene layer, as measured by a differential scanning calorimeter (DSC), is preferably 120°C or higher, more preferably 125°C or higher, from the viewpoint of improving heat resistance and stiffness while maintaining processability and adhesiveness, and is preferably 135°C or lower, more preferably 130°C or lower, from the viewpoint of improving adhesiveness while maintaining heat resistance.

[0065] When two or more types of polyethylene are used as the polyethylene constituting the linear low-density polyethylene layer, the density, MFR, and melting point of the linear low-density polyethylene layer can be measured values ​​for a mixture obtained by melt-blending two or more types of polyethylene using a known method. The melting point of the linear low-density polyethylene layer can be the peak temperature of the maximum melting peak.

[0066] The high-density polyethylene layer 1, the high-density polyethylene layer 2, and the linear low-density polyethylene layer may contain various additives within the scope of the present invention, such as heat stabilizers, weather stabilizers, antioxidants, ultraviolet absorbers, lubricants, slip agents, nucleating agents, antiblocking agents, antistatic agents, antifogging agents, pigments, dyes, inorganic or organic fillers, etc.

[0067] The thicknesses of the high-density polyethylene layer 1 and the high-density polyethylene layer 2 are each preferably 1 μm or more, more preferably 3 μm or more, and preferably 17 μm or less, more preferably 13 μm or less, even more preferably 10 μm or less, and even more preferably 7 μm or less, from the viewpoint of achieving a more appropriate range of orientation crystallinity. The thicknesses of the high-density polyethylene layer 1 and the high-density polyethylene layer 2 may be the same or different, but are preferably the same from the viewpoint of achieving a uniform amount of strain on the front and back sides of the polyethylene film (a) on the high-density polyethylene layer 1 side and the high-density polyethylene layer 2 side. The thickness of the linear low-density polyethylene layer is preferably 2 μm or more, more preferably 5 μm or more, and preferably 30 μm or less, more preferably 25 μm or less, even more preferably 20 μm or less, and even more preferably 15 μm or less, from the viewpoint of achieving a more appropriate range of orientation crystallinity.

[0068] <Method for Producing Polyethylene Film (a)> The polyethylene film (a) of this embodiment is preferably uniaxially stretched from the viewpoint of further improving the balance of performance such as hand-tearability, heat-sealability, twistability, impact resistance, transparency, and sealability. The polyethylene film (a) can be obtained, for example, by co-extrusion molding a high-density polyethylene resin for forming the high-density polyethylene layer 1, a linear low-density polyethylene resin for forming the linear low-density polyethylene layer, and a high-density polyethylene resin for forming the high-density polyethylene layer 2 in this order into a film, and then stretching the resulting film using a known stretched film production method such as a uniaxial stretching method. The molding apparatus and molding conditions are not particularly limited, and conventionally known molding apparatuses and molding conditions can be used. Examples of molding apparatuses that can be used include T-die extruders, multilayer T-die extruders, inflation molding machines, and multilayer inflation molding machines. The conditions for the uniaxial stretching method can be, for example, known conditions for producing stretched polyethylene films. More specifically, in the case of uniaxial stretching, the longitudinal stretching temperature may be set to 100° C. to 145° C., and the longitudinal stretching ratio may be set to 4.5 to 6 times.

[0069] <Biaxially oriented polyethylene film (b)> From the viewpoint of further improving the balance of performance among hand-tearability, heat-sealability, heat resistance, and impact resistance, the biaxially oriented polyethylene film (b) of the present embodiment preferably comprises two types of linear low-density polyethylene layers 1 and 2 having different densities, and more preferably comprises linear low-density polyethylene layer 1, linear low-density polyethylene layer 1, and linear low-density polyethylene layer 2, in this order.

[0070] In the biaxially oriented polyethylene film (b) of this embodiment, the linear low-density polyethylene layer 1 and the linear low-density polyethylene layer 2 may be formed using the same material or different materials. However, when different materials are used, it is preferable that the linear low-density polyethylene layer 1 and the linear low-density polyethylene layer 2 satisfy the following configuration.

[0071] From the viewpoint of further improving the balance of transparency, rigidity, heat resistance, and slip property, the content of linear low-density polyethylene in the linear low-density polyethylene layer 1 is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and still more preferably 98% by mass or more, based on the entire linear low-density polyethylene layer 1. There is no upper limit to the content of linear low-density polyethylene in the linear low-density polyethylene layer 1, but each content is, for example, 100% by mass or less.

[0072] The density of the linear low-density polyethylene layer 1, measured in accordance with JIS K 7112:1999, is preferably 0.910 g / cm3 from the viewpoint of achieving a better balance of mechanical properties, rigidity, and flexibility. ３ More preferably, 0.915 g / cm ３ More preferably, 0.920 g / cm ３ More preferably, 0.923 g / cm ３ More preferably, 0.925 g / cm ３ From the viewpoint of achieving a better balance between laminate strength and flexibility, it is preferably 0.955 g / cm ３ or less, more preferably 0.945 g / cm ３ More preferably, 0.940 g / cm ３ More preferably, 0.935 g / cm or less ３ More preferably, 0.930 g / cm or less ３ The following is the result.

[0073] The density of the linear low-density polyethylene constituting the linear low-density polyethylene layer 1, measured in accordance with JIS K 7112:1999, is preferably 0.910 g / cm3 from the viewpoint of achieving a better balance of mechanical properties, rigidity, and flexibility. ３ More preferably, 0.915 g / cm ３ More preferably, 0.920 g / cm ３ More preferably, 0.923 g / cm ３ More preferably, 0.925 g / cm ３From the viewpoint of achieving a better balance between laminate strength and flexibility, it is preferably 0.955 g / cm ３ or less, more preferably 0.945 g / cm ３ More preferably, 0.940 g / cm ３ More preferably, 0.935 g / cm or less ３ More preferably, 0.930 g / cm or less ３ The following is the result.

[0074] The melt flow rate (MFR) of the linear low-density polyethylene layer 1, measured in accordance with ASTM D1238 under conditions of 190°C and a load of 2.16 kg, is preferably 0.01 g / 10 min or more, more preferably 0.1 g / 10 min or more, even more preferably 1.0 g / 10 min or more, and still more preferably 1.5 g / 10 min or more, from the viewpoint of further improving processability; and from the viewpoint of improving the stiffness of the biaxially oriented polyethylene film (b) while maintaining the hand-tearability of the biaxially oriented polyethylene film (b), it is preferably 20 g / 10 min or less, more preferably 10 g / 10 min or less, even more preferably 5 g / 10 min or less, and still more preferably 3 g / 10 min or less. The melting point of the linear low-density polyethylene layer 1, as measured by a differential scanning calorimeter (DSC), is preferably 110°C or higher, more preferably 120°C or higher, even more preferably 125°C or higher, and is preferably 135°C or lower, more preferably 130°C or lower, from the viewpoint of improving heat resistance and stiffness while maintaining processability and adhesiveness.

[0075] The melt flow rate (MFR) of the linear low-density polyethylene constituting the linear low-density polyethylene layer 1, measured in accordance with ASTM D1238 under conditions of 190°C and a load of 2.16 kg, is preferably 0.01 g / 10 min or more, more preferably 0.1 g / 10 min or more, even more preferably 1.0 g / 10 min or more, and still more preferably 1.5 g / 10 min or more, from the viewpoint of further improving processability; and from the viewpoint of improving the stiffness of the biaxially oriented polyethylene film (b) while maintaining the hand-tearability of the biaxially oriented polyethylene film (b), it is preferably 20 g / 10 min or less, more preferably 10 g / 10 min or less, even more preferably 5 g / 10 min or less, and still more preferably 3 g / 10 min or less. The melting point of the linear low-density polyethylene constituting the linear low-density polyethylene layer 1, as measured by a differential scanning calorimeter (DSC), is preferably 110°C or higher, more preferably 120°C or higher, even more preferably 125°C or higher, and is preferably 135°C or lower, more preferably 130°C or lower, from the viewpoint of improving heat resistance and stiffness while maintaining processability and adhesiveness.

[0076] When two or more types of polyethylene are used as the polyethylene constituting the linear low-density polyethylene layer, the density, MFR, and melting point of the linear low-density polyethylene layer can be measured values ​​for a mixture obtained by melt-blending two or more types of polyethylene using a known method. The melting point of the linear low-density polyethylene layer can be the peak temperature of the maximum melting peak.

[0077] From the viewpoint of suppressing oriented crystallization in the surface layer of the biaxially oriented polyethylene film (b) and further improving the laminate strength, the content of linear low-density polyethylene in the linear low-density polyethylene layer 2 is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and still more preferably 98% by mass or more, based on the entire linear low-density polyethylene layer 2. There is no upper limit to the content of linear low-density polyethylene in the linear low-density polyethylene layer 2, but it is, for example, 100% by mass or less.

[0078] The density of the linear low-density polyethylene layer 2, as measured in accordance with JIS K 7112:1999, is preferably 0.905 / cm from the viewpoint of further improving the balance of mechanical properties, rigidity, and flexibility. ３ More preferably, 0.910 g / cm ３ More preferably, 0.915 g / cm ３ More preferably, 0.920 g / cm ３ From the viewpoint of further improving the balance of laminate strength and flexibility, it is preferably 0.955 g / cm ３ or less, more preferably 0.945 g / cm ３ More preferably, 0.940 g / cm ３ More preferably, 0.935 g / cm or less ３ More preferably, 0.930 g / cm or less ３ More preferably, 0.925 g / cm ３ The following is the result.

[0079] The density of the linear low-density polyethylene constituting the linear low-density polyethylene layer 2, measured in accordance with JIS K 7112:1999, is preferably 0.905 / cm from the viewpoint of further improving the balance of mechanical properties, rigidity, and flexibility. ３ More preferably, 0.910 g / cm ３ More preferably, 0.915 g / cm ３ More preferably, 0.920 g / cm ３ From the viewpoint of further improving the balance of laminate strength and flexibility, it is preferably 0.955 g / cm ３ or less, more preferably 0.945 g / cm ３ More preferably, 0.940 g / cm ３ More preferably, 0.935 g / cm or less ３ More preferably, 0.930 g / cm or less ３ More preferably, 0.925 g / cm ３ The following is the result.

[0080] The melt flow rate (MFR) of the linear low-density polyethylene layer 2, measured in accordance with ASTM D1238 under conditions of 190°C and a load of 2.16 kg, is preferably 0.05 g / 10 min or more, more preferably 0.5 g / 10 min or more, and even more preferably 2.0 g / 10 min or more, from the viewpoint of further improving processability; and from the viewpoint of improving the stiffness of the biaxially oriented polyethylene film (b) while maintaining the hand-tearability of the biaxially oriented polyethylene film (b), it is preferably 20 g / 10 min or less, more preferably 10 g / 10 min or less, even more preferably 7 g / 10 min or less, and even more preferably 4 g / 10 min or less. The melting point of the linear low-density polyethylene layer 2, as measured by a differential scanning calorimeter (DSC), is preferably 105°C or higher, more preferably 110°C or higher, even more preferably 115°C or higher, and even more preferably 120°C or higher, from the viewpoint of improving heat resistance and stiffness while maintaining processability and adhesiveness; and is preferably 135°C or lower, more preferably 130°C or lower, and even more preferably 125°C or lower, from the viewpoint of improving adhesiveness while maintaining heat resistance.

[0081] The melt flow rate (MFR) of the linear low-density polyethylene constituting the linear low-density polyethylene layer 2, measured in accordance with ASTM D1238 under conditions of 190°C and a load of 2.16 kg, is preferably 0.05 g / 10 min or more, more preferably 0.5 g / 10 min or more, and even more preferably 2.0 g / 10 min or more, from the viewpoint of further improving processability; and from the viewpoint of improving the stiffness of the biaxially oriented polyethylene film (b) while maintaining the hand-tearability of the biaxially oriented polyethylene film (b), it is preferably 20 g / 10 min or less, more preferably 10 g / 10 min or less, even more preferably 7 g / 10 min or less, and even more preferably 4 g / 10 min or less. The melting point of the linear low-density polyethylene constituting the linear low-density polyethylene layer 2, as measured by a differential scanning calorimeter (DSC), is preferably 105°C or higher, more preferably 110°C or higher, even more preferably 115°C or higher, and even more preferably 120°C or higher, from the viewpoint of improving heat resistance and stiffness while maintaining processability and adhesiveness; and is preferably 135°C or lower, more preferably 130°C or lower, and even more preferably 125°C or lower, from the viewpoint of improving adhesiveness while maintaining heat resistance.

[0082] When two or more types of polyethylene are used as the polyethylene constituting the linear low-density polyethylene layer 2, the density, MFR, and melting point of the linear low-density polyethylene layer 2 can be measured values ​​for a mixture obtained by melt-blending two or more types of polyethylene by a known method. The melting point of the linear low-density polyethylene layer 2 can be the peak temperature of the maximum melting peak.

[0083] Within the scope of the present invention, the linear low-density polyethylene layer 1 and the linear low-density polyethylene layer 2 may contain various additives, such as heat stabilizers, weather stabilizers, antioxidants, ultraviolet absorbers, lubricants, slip agents, nucleating agents, antiblocking agents, antistatic agents, antifogging agents, pigments, dyes, and inorganic or organic fillers.

[0084] From the viewpoint of achieving a more appropriate range of oriented crystallinity, the thickness of the linear low-density polyethylene layer 1 is preferably 0.5 μm or more, more preferably 2 μm or more, even more preferably 5 μm or more, and preferably 50 μm or less, more preferably 30 μm or less. From the viewpoint of achieving a more appropriate range of oriented crystallinity, the thickness of the linear low-density polyethylene layer 2 is preferably 0.5 μm or more, more preferably 2 μm or more, even more preferably 5 μm or more, and preferably 50 μm or less, more preferably 30 μm or less, even more preferably 10 μm or less, and even more preferably 5 μm or less.

[0085] <Method for Producing Biaxially Stretched Polyethylene Film (b)> The biaxially oriented polyethylene film (b) of this embodiment can be obtained by various known methods, for example, by extruding or co-extruding the linear low-density polyethylene forming the linear low-density polyethylene layer 1 and the linear low-density polyethylene forming the linear low-density polyethylene layer 2, and then biaxially stretching the films in the machine direction (MD) and transverse direction (TD) within the above-mentioned ranges using a tubular or flat (tenter) system. The biaxial stretching may be simultaneous biaxial stretching or sequential biaxial stretching. Among these systems, the biaxially oriented polyethylene film (b) obtained by the flat system is preferred because it has superior transparency. When using the flat system, the film is typically obtained by stretching an extrusion-molded sheet 2 to 12 times, preferably 3 to 10 times, in the machine direction at a temperature range of 90 to 125°C, and then stretching 3 to 15 times, preferably 5 to 15 times, in the transverse direction at a temperature range of 90 to 140°C. For example, for the biaxially oriented polyethylene film (b), the stretching ratio in the transverse (TD) direction can be greater than that in the longitudinal (MD) direction.

[0086] <Polyethylene film (c)> From the viewpoint of further improving the balance of performance among hand-tearability, heat-sealability, cost, and dimensional stability, the polyethylene film (c) of the present embodiment preferably includes a low-density polyethylene layer, and more preferably is a single layer of low-density polyethylene.

[0087] The density of the low-density polyethylene layer, measured in accordance with JIS K 7112:1999, is preferably 0.870 g / cm3 from the viewpoint of achieving a better balance of heat resistance, transparency, mechanical properties, and rigidity. ３ More preferably, 0.880 g / cm ３ More preferably, 0.890 g / cm ３ More preferably, 0.900 g / cm ３ More preferably, 0.905 g / cm ３ More preferably, 0.910 g / cm ３ More preferably, 0.915 g / cm ３ From the viewpoint of achieving a better balance between laminate strength and film formability, it is preferably 0.940 g / cm ３ or less, more preferably 0.935 g / cm ３ More preferably, 0.930 g / cm or less ３ More preferably, 0.925 g / cm ３ More preferably, 0.920 g / cm ３ The following is the result.

[0088] The density of the low-density polyethylene constituting the low-density polyethylene layer, measured in accordance with JIS K 7112:1999, is preferably 0.870 g / cm3 from the viewpoint of further improving the balance of heat resistance, transparency, mechanical properties, and rigidity. ３ More preferably, 0.880 g / cm ３ More preferably, 0.890 g / cm ３ More preferably, 0.900 g / cm ３ More preferably, 0.905 g / cm ３ More preferably, 0.910 g / cm ３ More preferably, 0.915 g / cm ３ From the viewpoint of achieving a better balance between laminate strength and film formability, it is preferably 0.940 g / cm ３ or less, more preferably 0.935 g / cm ３ More preferably, 0.930 g / cm or less ３More preferably, 0.925 g / cm ３ More preferably, 0.920 g / cm ３ The following is the result.

[0089] The melt flow rate (MFR) of the low-density polyethylene layer, measured in accordance with ASTM D1238 under conditions of 190°C and a load of 2.16 kg, is preferably 0.1 g / 10 min or more, more preferably 1.0 g / 10 min or more, even more preferably 2.0 g / 10 min or more, and still more preferably 3.0 g / 10 min or more, from the viewpoint of further improving the balance between fluidity and moldability; and from the viewpoint of improving the stiffness of the polyethylene film (c) while maintaining the hand-tearability of the polyethylene film (c), is preferably 20.0 g / 10 min or less, more preferably 15.0 g / 10 min or less, even more preferably 10.0 g / 10 min or less, even more preferably 7.0 g / 10 min or less, and still more preferably 5.0 g / 10 min or less. The melting point of the low-density polyethylene layer, as measured by a differential scanning calorimeter (DSC), is preferably 90°C or higher, more preferably 100°C or higher, and even more preferably 110°C or higher, from the viewpoint of improving heat resistance and stiffness while maintaining processability and adhesiveness, and is preferably 130°C or lower, more preferably 120°C or lower, from the viewpoint of improving adhesiveness while maintaining heat resistance.

[0090] The melt flow rate (MFR) of the low-density polyethylene constituting the low-density polyethylene layer, measured in accordance with ASTM D1238 under conditions of 190°C and a load of 2.16 kg, is preferably 0.1 g / 10 min or more, more preferably 1.0 g / 10 min or more, even more preferably 2.0 g / 10 min or more, and still more preferably 3.0 g / 10 min or more, from the viewpoint of further improving the balance between fluidity and moldability; and from the viewpoint of improving the stiffness of the polyethylene film (c) while maintaining the hand-tearability of the polyethylene film (c), is preferably 20.0 g / 10 min or less, more preferably 15.0 g / 10 min or less, even more preferably 10.0 g / 10 min or less, even more preferably 7.0 g / 10 min or less, and still more preferably 5.0 g / 10 min or less. The melting point of the low-density polyethylene constituting the low-density polyethylene layer, as measured by a differential scanning calorimeter (DSC), is preferably 90°C or higher, more preferably 100°C or higher, and even more preferably 110°C or higher, from the viewpoint of improving heat resistance and stiffness while maintaining processability and adhesiveness, and is preferably 130°C or lower, more preferably 120°C or lower, from the viewpoint of improving adhesiveness while maintaining heat resistance.

[0091] <Method for producing polyethylene film (c)> The polyethylene film (c) of this embodiment is preferably not stretched, from the viewpoint of further improving the balance of performance among hand-tearability, heat-sealability, cost, and dimensional stability. The polyethylene film (c) can be obtained, for example, by extrusion molding a low-density polyethylene resin for forming the low-density polyethylene layer into a film. The molding apparatus and molding conditions are not particularly limited, and conventionally known molding apparatuses and molding conditions can be used. As the molding apparatus, a T-die extruder, a multi-layer T-die extruder, an inflation molding machine, a multi-layer inflation molding machine, or the like can be used.

[0092] <Packaging Material> The packaging material of this embodiment includes the packaging film 100 of this embodiment. As a result, the packaging material of this embodiment has an improved balance of hand-tearability and heat-sealability. The packaging material of this embodiment may be formed using only the packaging film 100 of this embodiment, or may be formed by laminating other layers. The other layers may further include one or more selected from the group consisting of an inorganic layer, a substrate layer, a coating layer, an adhesive layer, and a heat-seal layer. From the viewpoint of ease of recycling, when these layers are laminated, they are preferably formed from a polyethylene-based resin.

[0093] <Packaging> The packaging of this embodiment includes the packaging material of this embodiment and an article inside the packaging material, with the polyethylene film (a) on the outer side and the polyethylene film (c) on the article side. By having the polyethylene film (a) on the outer side and the polyethylene film (c) on the article side, the balance of hand-tearability and heat-sealability can be further improved. Depending on the application, only a portion of the packaging may be made of the packaging material of this embodiment, or substantially the entire packaging may be made of the packaging material of this embodiment.

[0094] The method for producing the package of this embodiment is not particularly limited, and any method known in the field of packaging materials / packages, such as heat sealing or fusing, can be used as appropriate.

[0095] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention.

[0096] The present embodiment will be described in detail below with reference to examples and comparative examples, but the present embodiment is not limited to the descriptions of these examples.

[0097] <Raw Materials> The raw materials used in the Examples and Comparative Examples are shown below. The density was measured in accordance with JIS K 7112:1999. The MFR was measured in accordance with ASTM D1238 under conditions of 190°C and a load of 2160 g. The melting point was measured using a differential scanning calorimeter (DSC). Specifically, using a differential scanning calorimeter (product name: Q200DSC, manufactured by TA Instruments), differential scanning calorimetry was performed under a nitrogen gas flow, consisting of a process of increasing the temperature from -50°C to 250°C at a heating rate of 5°C / min and a process of decreasing the temperature from 250°C to -50°C at a heating rate of 5°C / min, and the peak temperature of the maximum melting peak in the obtained DSC curve was taken as the melting point (°C).

[0098] High density polyethylene 1 (HDPE1), density: 0.949 g / cm ３ , MFR: 1.1 g / 10 min, melting point: 130 ° C. Linear low density polyethylene 1 (LLDPE1), density: 0.928 g / cm ３ , MFR: 1.7 g / 10 min, melting point: 127 ° C. Linear low density polyethylene 2 (LLDPE2), density: 0.927 g / cm ３ , MFR: 1.9 g / 10 min, melting point: 127 ° C. Linear low density polyethylene 3 (LLDPE3), density: 0.922 g / cm ３ , MFR: 2.7 g / 10 min, melting point: 122°C

[0099] <Preparation of Polyethylene Film (a)> High density polyethylene 1 (HDPE1) / linear low density polyethylene 1 (LLDPE1) / high density polyethylene 1 (HDPE1) were mixed in this order in a mass ratio of 25 / 50 / 25 and T-die extrusion molded into a film to obtain a cast sheet, which was then subjected to uniaxial stretching treatment to prepare a polyethylene film (a) having a thickness of 20 μm or 25 μm. The density of the obtained polyethylene film (a) was 0.940 g / cm ３ The extrusion conditions and uniaxial stretching conditions are as follows: Multilayer extruder: 75 mmφ multilayer T-die extruder (L / D=29, manufactured by Mitsubishi Heavy Industries, Ltd.) Extrusion set temperature: 230°C Processing speed: 70 m / min Longitudinal stretching temperature: 110 to 130°C Longitudinal stretching ratio: 5 times

[0100] <Preparation of Biaxially Stretched Polyethylene Film (b)> Linear low density polyethylene 2 (LLDPE2) / linear low density polyethylene 2 (LLDPE2) / linear low density polyethylene 3 (LLDPE3) were mixed in this order in a mass ratio of 10 / 80 / 10 and T-die extrusion molded into a film to obtain a cast sheet, which was then subjected to a biaxial stretching treatment to prepare a biaxially oriented polyethylene film (b) having a thickness of 25 μm or 30 μm. The density of the obtained biaxially oriented polyethylene film (b) was 0.930 g / cm ３ The extrusion conditions and biaxial stretching conditions are as follows: Multilayer extruder: 60 mmφ multilayer T-die extruder (L / D=27, manufactured by Mitsubishi Heavy Industries, Ltd.) Processing speed: 20 m / min Longitudinal stretching temperature: 100 to 120°C Longitudinal stretching ratio: 5 times Transverse stretching temperature: 110 to 130°C Transverse stretching ratio: 10 times

[0101] <Polyethylene film (c)> The polyethylene film (c) was a non-stretched polyethylene film (T.U.X MC-S, manufactured by Mitsui Chemicals Tocello, Inc., density: 0.918 g / cm ３ , MFR: 3.8 g / 10 min, melting point: 113°C, thickness: 25 μm, 70 μm, 100 μm) were used.

[0102] <Preparation of Packaging Film> (Example 1) First, one side of a 20 μm polyethylene film (a) and both sides of a 30 μm biaxially oriented polyethylene film (b) were subjected to a corona treatment. Next, using a polyester-based adhesive (Takelac A310, manufactured by Mitsui Chemicals, Inc.), the corona-treated side of the polyethylene film (a) was dry-laminated to the biaxially oriented polyethylene film (b), and the resulting film was aged at 40°C for 48 hours to obtain a two-layer film. Next, using a polyester-based adhesive (Takelac A310, manufactured by Mitsui Chemicals, Inc.), the side of the biaxially oriented polyethylene film (b) of the resulting two-layer film was dry-laminated to a 70 μm polyethylene film (c) in the same manner, and the resulting film was aged at 40°C for 48 hours. As a result, a packaging film of Example 1 was obtained, having a layer structure of polyethylene film (a) / adhesive layer / biaxially oriented polyethylene film (b) / adhesive layer / polyethylene film (c). The thickness of each adhesive layer was 3 μm.

[0103] (Example 2) A packaging film of Example 2 was obtained in the same manner as in Example 1, except that a 25 μm polyethylene film (a), a 25 μm biaxially stretched polyethylene film (b), and a 100 μm polyethylene film (c) were used.

[0104] (Comparative Example 1) First, one side of a 25 μm polyethylene film (a) was subjected to a corona treatment. Next, using a polyester-based adhesive (Takelac A310, manufactured by Mitsui Chemicals, Inc.), the corona-treated side of the polyethylene film (a) was dry-laminated to a 100 μm polyethylene film (c), and the resulting laminate was aged at 40° C. for 48 hours. As a result, a packaging film of Comparative Example 1 was obtained, having a layer structure of polyethylene film (a) / adhesive layer / polyethylene film (c). The thickness of the adhesive layer was 3 μm.

[0105] (Comparative Example 2) A 25 μm polyethylene film (c) and a 100 μm polyethylene film (c) were dry-laminated using a polyester adhesive (Takelac A310, manufactured by Mitsui Chemicals, Inc.), and then aged for 48 hours at 40° C. As a result, a packaging film of Comparative Example 2 having a layer structure of polyethylene film (c) / adhesive layer / polyethylene film (c) was obtained. The thickness of the adhesive layer was 3 μm.

[0106] (Comparative Example 3) First, one side of a 25 μm biaxially oriented polyethylene film (b) and both sides of a 25 μm polyethylene film (a) were subjected to a corona treatment. Next, the corona-treated side of the biaxially oriented polyethylene film (b) was dry-laminated to the polyethylene film (a) using a polyester-based adhesive (Takelac A310, manufactured by Mitsui Chemicals, Inc.), and further aged at 40°C for 48 hours to obtain a two-layer film. Next, the polyethylene film (a) side of the obtained two-layer film was similarly dry-laminated to a 100 μm polyethylene film (c) using a polyester-based adhesive (Takelac A310, manufactured by Mitsui Chemicals, Inc.), and further aged at 40°C for 48 hours. As a result, a packaging film of Comparative Example 3 was obtained, having a layer structure of biaxially oriented polyethylene film (b) / adhesive layer / polyethylene film (a) / adhesive layer / polyethylene film (c). The thickness of the adhesive layer was 3 μm.

[0107] <Tensile Modulus, Stress at Break, and Elongation at Break> The packaging films of each Example and Comparative Example were cut into a width of 15 mm and a length of 150 mm to prepare test specimens. The test specimens were then measured for tensile modulus, stress at break, and elongation at break in the MD and TD directions in accordance with JIS K7127:1999 using a tensile tester (Orientec Co., Ltd., RTC-1225) at a temperature of 23±2°C, 50±5% RH, and a pulling rate of 5 mm / min. The results are shown in Table 1.

[0108] <Lamination strength in MD direction> The packaging films of each Example and Comparative Example were cut into a width of 15 mm and a length of 70 mm to prepare test specimens. The maximum peel strength in the MD direction of each test specimen was then measured using a Tensilon universal testing machine (manufactured by Orientec Co., Ltd., RTC-1225) at a tensile speed of 300 mm / min and a temperature of 23°C, and this was taken as the laminate strength in the MD direction (N / 15 mm). The results are shown in Table 1.

[0109] <Heat Seal Strength> Two test pieces were prepared for each of the packaging films in each Example and Comparative Example, each cut to a width of 70 mm and a length of 70 mm. The two test pieces were then overlapped with the polyethylene film (c) facing each other, and heat-sealed using a heat seal tester (TP701-B, manufactured by Tester Sangyo Co., Ltd.) under conditions of an upper temperature (heat seal temperature) of 140°C, a lower temperature of 25°C, a seal pressure of 0.2 MPa, and a seal time of 1 second. The heat-sealed test pieces were then removed and cut to a width of 15 mm in the MD or TD direction. The maximum peel strength of the heat-sealed 15 mm-wide test pieces was measured using a Tensilon universal testing machine (RTC-1225, manufactured by Orientec Co., Ltd.) at a tensile speed of 300 mm / min and a temperature of 23°C, and this was recorded as the heat seal strength (N / 15 mm) in the MD or TD direction. The results are shown in Table 1.

[0110] <Tear Strength> The packaging films of each Example and Comparative Example were cut into test pieces with a width of 63.5 mm and a length of 50 mm. The test pieces were then subjected to measurement of tear strength (mN) in the MD and TD directions using a light-load tear tester (manufactured by Toyo Seiki Seisaku-sho, Model-D) under the following conditions: a pendulum weight of 720 g, a cut length of 12.7 mm, and a pendulum lift angle of 90°. The results are shown in Table 1.

[0111] <Evaluation of Hand Tearability> The packaging films of each Example and Comparative Example were cut into a size of 70 mm wide x 70 mm long to prepare test specimens. Next, a 2 mm equilateral triangular notch was made at the edge of the test specimen with scissors, and the test specimen was manually evaluated for tearability starting from this notch. The hand tearability was evaluated according to the following criteria: A: The test specimen could be torn to 50 mm or more. B: The test specimen could not be torn to 50 mm or more.

[0112]

[0113] This application claims priority based on Japanese Patent Application No. 2023-181356, filed October 20, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0114] 100 Packaging film 110 Adhesive layer a Polyethylene film (a) b Biaxially oriented polyethylene film (b) c Polyethylene film (c)

Claims

1. One or more polyethylene films (a) selected from the group consisting of unoriented polyethylene films and uniaxially oriented polyethylene films, Biaxially oriented polyethylene film (b) and One or more polyethylene films (c) selected from the group consisting of unoriented polyethylene films and uniaxially oriented polyethylene films, A packaging film containing these elements in this order.

2. The packaging film according to claim 1, wherein the polyethylene film (a) includes a uniaxially oriented polyethylene film.

3. The packaging film according to claim 1 or 2, wherein the polyethylene film (c) includes an unstretched polyethylene film.

4. The density of the polyethylene film (a), measured in accordance with JIS K 7112:1999, is 0.917 g / cm³. ３ 0.970g / cm or more ３ The packaging film according to claim 1 or 2, which is as follows:

5. The density of the biaxially oriented polyethylene film (b), measured in accordance with JIS K 7112:1999, is 0.917 g / cm³. ３ 0.970g / cm or more ３ The packaging film according to claim 1 or 2, which is as follows:

6. The packaging film according to claim 1 or 2, wherein the thickness of the polyethylene film (a) is 5 μm or more and 50 μm or less.

7. The packaging film according to claim 1 or 2, wherein the thickness of the biaxially oriented polyethylene film (b) is 5 μm or more and 50 μm or less.

8. The packaging film according to claim or 2, wherein the thickness of the polyethylene film (c) is 10 μm or more and 200 μm or less.

9. The packaging film according to claim 1 or 2, wherein the ratio A / B of the thickness A of the polyethylene film (a) to the thickness B of the biaxially oriented polyethylene film (b) is 0.3 or more and 3.0 or less.

10. The packaging film according to claim 1 or 2, wherein the ratio C / B of the thickness C of the polyethylene film (c) to the thickness B of the biaxially oriented polyethylene film (b) is 1.1 or more and 10.0 or less.

11. The packaging film according to claim 1 or 2, further comprising an adhesive layer between the polyethylene film (a) and the biaxially oriented polyethylene film (b), and between the biaxially oriented polyethylene film (b) and the polyethylene film (c).

12. The packaging film according to claim 1 or 2, wherein the polyethylene film (a) is the outermost layer.

13. The packaging film according to claim 1 or 2, wherein the polyethylene film (c) is the innermost layer.

14. The packaging film according to claim 1 or 2, wherein, in accordance with JIS K7127:1999, the tensile modulus of the packaging film in the MD direction is 170 MPa or more and 500 MPa or less, and the tensile modulus of the TD direction is 160 MPa or more and 600 MPa or less, as measured using a tensile testing machine under the conditions of a measurement temperature of 23 ± 2 °C, 50 ± 5% RH, and a tensile speed of 5 mm / min.

15. The packaging film according to claim 1 or 2, wherein, in accordance with JIS K7127:1999, the breaking point stress of the packaging film in the MD direction is 20 MPa or more and 50 MPa or less, and the breaking point stress in the TD direction is 10 MPa or more and 40 MPa or less, as measured using a tensile testing machine under the conditions of a measurement temperature of 23 ± 2°C, 50 ± 5% RH, and a tensile speed of 5 mm / min.

16. The packaging film according to claim 1 or 2, wherein, in accordance with JIS K7127:1999, the elongation at the breaking point of the packaging film in the MD direction is 50% or more and 200% or less, and the elongation at the breaking point in the TD direction is 50% or more and 200% or less, as measured using a tensile testing machine under the conditions of a measurement temperature of 23±2°C, 50±5%RH, and a tensile speed of 5 mm / min.

17. The packaging film according to claim 1 or 2, wherein the lamination strength in the MD direction of the packaging film by the method 1 described below is 3.0 N / 15 mm or more. (Method 1) The aforementioned packaging film is cut into pieces measuring 15 mm in width and 70 mm in length to be used as test specimens. Next, the maximum peel strength of the test specimen is measured using a Tensilon universal tester under the conditions of a tensile speed of 300 mm / min and a temperature of 23°C, and this is defined as the laminate strength (N / 15 mm).

18. The packaging film according to claim 1 or 2, wherein the heat seal strength in the MD direction of the packaging film is 30 N / 15 mm or more and the heat seal strength in the TD direction is 25 N / 15 mm or more, according to method 2 below. (Method 2) Two test pieces are prepared by cutting the aforementioned packaging film to a width of 70 mm and a length of 70 mm. Next, the two prepared test pieces are placed on top of each other so that the polyethylene film (c) faces each other, and then heat-sealed using a heat seal tester under the conditions of an upper temperature (heat seal temperature) of 140°C, a lower temperature of 25°C, a seal pressure of 0.2 MPa, and a seal time of 1 second. Next, the heat-sealed test pieces are removed and cut to a width of 15 mm. Then, the maximum peel strength of the heat-sealed 15 mm wide test piece is measured using a Tensilon universal tester under the conditions of a tensile speed of 300 mm / min and a temperature of 23°C, and this is defined as the heat seal strength (N / 15 mm).

19. The packaging film according to claim or 2, wherein the tear strength in the MD direction of the packaging film is 100 mN or more and 3000 mN or less, and the tear strength in the TD direction is 100 mN or more and 2000 mN or less, according to method 3 below. (Method 3) The packaging film is cut to a width of 63.5 mm and a length of 50 mm to prepare a test piece. The tear strength (mN) of the test piece is then measured using a light-load tear tester under the conditions of a pendulum weight of 720 g, a cut length of 12.7 mm, and a pendulum lifting angle of 90°.

20. A packaging material comprising the packaging film described in claim 1 or 2.

21. The packaging material described in claim 20, and an article placed inside the packaging material, A packaging body in which the polyethylene film (a) is on the outside and the polyethylene film (c) is on the article side.