Packaging

Abstract

Provided is a packaging body (10) composed of a packaging film, wherein the outermost layer of the packaging body is a polyethylene-based resin layer, and the polyethylene-based resin layer is stretched uniaxially or biaxially.

Description

[Technical Field]

[0001] This invention relates to packaging. [Background technology]

[0002] For example, packaging bags such as pouches used as packaging materials for food, toiletries, pharmaceuticals, car supplies such as vehicle oil, washer fluid, and coolant, industrial lubricants, and heat transfer fluids such as oil and water, are composed of packaging materials consisting of a heat seal layer and a base layer.

[0003] Examples of technologies relating to packaging bags consisting of a heat-seal layer and a base material layer include those described in Patent Document 1 (Japanese Patent Application Publication No. 2018-154133).

[0004] Patent Document 1 describes a packaging bag made of a laminated film which is formed by laminating a single-layer film made of a polyethylene resin composition or a multilayer sealant film containing at least one layer made of the polyethylene resin composition with a base film. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2018-154133 [Overview of the project] [Problems that the invention aims to solve]

[0006] In recent years, with the growing environmental awareness, packaging films are required to be easily recyclable. From the perspective of making packaging films easier to recycle, one possible approach is to construct the packaging film using as few single materials (monomaterials) as possible. According to the inventors' studies, from the perspective of aiming for monomaterialization, the following problems have been identified with packaging made of a packaging film with a polyethylene resin layer as the base layer. First, as shown in Figures 2 and 3, when manufacturing a package 1 using a packaging film with a polyethylene resin layer 4 as the base layer, there is a step of heat-sealing the heat seal layers 2 together. At this time, for example, at the bottom 3 of the package 1, the outermost polyethylene resin layers 4 come into contact with each other. The inventors' investigations have revealed that during the process of heat-sealing the heat seal layers 2 together, the outermost polyethylene resin layers 4 fuse together. It has also become clear that the polyethylene resin layers fuse to the heat seal bar used for heat sealing. Thus, the inventors have found that in packaging materials where the outermost layer is a polyethylene resin layer, heat fusion of the outermost layer may occur during the manufacturing process.

[0007] This invention has been made in view of the above circumstances, and provides a packaging body in which heat sealing of the outermost layer is suppressed. [Means for solving the problem]

[0008] The inventors diligently conducted research to achieve the above objectives. As a result, they discovered that in a packaging body where the outermost layer is a polyethylene resin layer, the heat sealing of the outermost layer can be suppressed by uniaxial or biaxial stretching of the polyethylene resin layer, thus completing the present invention.

[0009] In other words, according to the present invention, the following packaging is provided.

[0010] [1] A package made of packaging film, The outermost layer is a polyethylene resin layer. A packaging body in which the above polyethylene resin layer is uniaxially or biaxially stretched. [2] In the packaging described in [1] above, A package in which the melting point of the polyethylene-based resin layer constituting the polyethylene-based resin layer is 100°C or higher and 150°C or lower. [3] In the package according to [1] or [2] above, A package having a heat-sealing layer on the innermost layer of the package. [4] In the package according to any one of [1] to [3] above, A package in which the heat-sealing layer contains a polyethylene-based resin. [5] In the package according to [4] above, A package in which the melting point of the polyethylene-based resin constituting the heat-sealing layer is 90°C or higher and 140°C or lower. [[ID=2E]] [6] In the package according to [5] above, A package in which when the whole package is 100% by mass, 90% by mass or more of the package is a polyethylene-based resin. [Effect of the Invention]

[0011] [[ID=3E]] According to the present invention, it is possible to provide a package in which heat fusion of the outermost layer is suppressed. [Brief Explanation of Drawings]

[0012] [Figure 1] It is a perspective view schematically showing an example of the structure of a package according to an embodiment of the present invention. [Figure 2] It is a front view schematically showing an example of the structure of a conventional package. [Figure 3] It is a cross-sectional view taken along the line X-X' of the package shown in FIG. 2. [Mode for Carrying Out the Invention]

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings are schematic and do not match the actual dimensional ratios. Also, "A to B" of the numerical range represents A or more and B or less unless otherwise specified.

[0014] <Package> Figure 1 is a schematic perspective view showing an example of the structure of a packaging body 10 according to an embodiment of the present invention. In this embodiment, the packaging body 10 is a packaging body made of packaging film, the outermost layer being a polyethylene resin layer, and this polyethylene resin layer is uniaxially or biaxially stretched. This makes it possible to suppress the heat fusion between the outermost polyethylene resin layers in a packaging body where the outermost layer is a uniaxially or biaxially stretched polyethylene resin layer, during the process of heat-sealing the heat seal layers together. Furthermore, it is possible to suppress the fusion of the outermost polyethylene resin layer to the heat seal bar during the heat sealing process.

[0015] In this embodiment, the packaging refers to a packaging bag itself or a bag containing articles, used for the purpose of containing articles such as food, pharmaceuticals, healthcare products, daily necessities, industrial products, car supplies such as vehicle oil, washer fluid, and coolant, industrial lubricants, and heat transfer fluids such as oil and water. The packaging form of the packaging according to this embodiment includes, for example, a three-sided bag, a four-sided bag, a pillow bag, a gusseted bag, a stick bag, a gusseted bag, a pouch, etc., which have a heat-sealed portion formed by heat fusion on all or part of the periphery. In addition to articles, oxygen absorbers and the like may be placed inside the packaging.

[0016] The packaging 10 according to this embodiment typically has a heat-seal layer on the innermost layer (the outermost layer on the inside side of the packaging). By heat-sealing the heat-seal layers of the packaging film together, the packaging 10 according to this embodiment can be manufactured.

[0017] In this embodiment, from the viewpoint of improving recyclability, it is preferable that, when the entire package 10 is considered as 100% by mass, 90% or more of the package is made of polyethylene resin, more preferably 95% or more by mass of the package is made of polyethylene resin, even more preferably 98% or more by mass of the package is made of polyethylene resin, and even more preferably 99% or more by mass of the package is made of polyethylene resin. As a result, the packaging is composed almost entirely of a single material (monomaterial), which reduces the work required to separate the materials that make up the packaging 10, thereby improving the recyclability of the packaging 10.

[0018] <Packaging film> As the packaging film according to this embodiment, for example, a film can be used that comprises a polyethylene resin layer containing a polyethylene resin and a heat-seal layer provided on at least one surface of the polyethylene resin layer. Here, the polyethylene resin layer may be a single layer or two or more layers.

[0019] The thickness of the packaging film according to this embodiment can be arbitrarily set according to desired purposes such as water vapor barrier properties, cost, mechanical strength, transparency, recyclability, appearance, moldability, and lightweight, and is not particularly limited. The thickness is usually 10 μm to 220 μm, preferably 15 μm to 190 μm, and more preferably 20 μm to 175 μm. When the thickness of the packaging film according to this embodiment is within the above range, a better balance of mechanical properties, handling, appearance, moldability, and lightweight properties is achieved.

[0020] The following describes each layer that constitutes the packaging film according to this embodiment.

[0021] [Polyethylene resin layer] The polyethylene resin layer (also referred to as the base layer) according to this embodiment is formed, for example, by uniaxial or biaxial stretching a film composed of a resin composition containing a polyethylene resin.

[0022] The thickness of the polyethylene resin layer according to this embodiment is not particularly limited, as it can be arbitrarily set according to desired purposes such as water vapor barrier properties, cost, mechanical strength, transparency, recyclability, appearance, moldability, and lightweight properties. However, it is usually 0.5 μm to 100 μm, preferably 1.0 μm to 75 μm, and more preferably 1.5 μm to 50 μm. When the thickness of the polyethylene resin layer is within the above range, a better balance of mechanical properties, handling, appearance, moldability, and lightweight properties is achieved.

[0023] The polyethylene resin layer according to this embodiment may include at least an outermost layer that is uniaxially or biaxially stretched, and may be a single layer consisting only of the outermost layer, or it may be a configuration in which multiple layers made of a resin composition containing polyethylene resin are laminated together. In a configuration where multiple layers are laminated, each composed of a resin composition containing polyethylene resin, layers other than the outermost layer (also called the outermost layer) of the packaging include, for example, a core layer and a laminate layer. From the viewpoint of film moldability and web handling during winding, it is preferable to provide a core layer and a laminate layer. The core layer is a layer located between the outermost layer and the laminate layer in the polyethylene resin layer, and the laminate layer is a layer located on the surface opposite to the outermost layer in the polyethylene resin layer. The polyethylene resin layer may consist only of the outermost layer and the laminate layer. Furthermore, in the polyethylene resin layer, at least the outermost layer may be uniaxially or biaxially stretched, and the core layer and laminate layer may or may not be stretched. The outermost layer thickness is, for example, 0.05 μm to 10 μm, specifically 1.0 μm to 6 μm. The core layer thickness is, for example, 0.4 μm to 49.9 μm, specifically 1 μm to 48 μm. The laminate layer thickness is, for example, 0.05 μm to 10 μm, specifically 1.0 μm to 6 μm. Furthermore, methods for laminating multiple layers composed of a resin composition containing polyethylene resin include, for example, dry lamination; extrusion lamination; heat fusion methods such as extruding resin and laminating the extruded resin onto the surface layer; and methods that combine dry lamination, extrusion lamination, and heat fusion.

[0024] (Polyethylene resin composition) The polyethylene resin composition according to this embodiment includes a polyethylene resin. The polyethylene resin content in the polyethylene resin composition (i.e., polyethylene resin layer) according to this embodiment is preferably 90% to 100% by mass, more preferably 95% to 100% by mass, even more preferably 98% to 100% by mass, and particularly preferably 99% to 100% by mass, when the total polyethylene resin composition is considered as 100% by mass. This allows for a better balance of water vapor barrier properties, cost, mechanical strength, transparency, recyclability, appearance, moldability, and lightweight properties.

[0025] (Polyethylene resin) Examples of polyethylene resins that constitute the polyethylene resin layer according to this embodiment include one or more polyethylene resins such as high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear polyethylene, and ultra-high molecular weight polyethylene. Among these, one or more of high-density polyethylene, medium-density polyethylene, low-density polyethylene, and linear polyethylene are preferred, and it is even more preferable to have linear polyethylene alone, or to have linear polyethylene in an amount of 20% by mass or more, and to have at least one of high-density polyethylene, medium-density polyethylene, and low-density polyethylene. From the viewpoint of suppressing whitening and improving the transparency of the packaging, it is preferable to combine two or more polyethylene-based resins. Whitening is caused by the crystallization of polyethylene. By using two or more polyethylene-based resins in combination, the polyethylene-based resin layer tends to become amorphous, which can suppress crystallization and thus reduce whitening. Factors to consider when combining two or more polyethylene-based resins include MFR, density, and melting point. Specifically, when combining two or more polyethylene-based resins, it is preferable to meet at least one of the following conditions (i) to (iii) (methods for measuring MFR and density will be described later). (i) Two polyethylene resins with MFRs differing by 0.5 g / 10 min or more are used in combination. In this case, it is preferable that the ratio of the two resins be the same by mass, or that the resin with the lower MFR is used in greater proportions. (ii) Density is 10 kg / m³ 3 The above-mentioned different polyethylene resins are combined. In this case, it is preferable that the ratio of the two resins be the same by mass, or that the resin with the lower density be used in greater proportions. (iii) Combine polyethylene resins with melting points that differ by 1°C or more. In this case, it is preferable that the ratio of the two resins be the same by mass, or that the resin with the lower melting point be used in greater proportions. If the polyethylene resin layer has a multilayer structure as described above (for example, a three-layer structure consisting of an outermost layer, a core layer, and a laminate layer), then one layer may contain two or more types of polyethylene-based resins, or two or more layers may each contain two or more types of polyester resins. Of course, each layer within the polyethylene resin layer may be composed of only one type of polyethylene-based resin.

[0026] The melting point of the polyethylene resin described above is preferably in the range of 100°C or higher, more preferably 120°C or higher, even more preferably 125°C or higher, preferably 150°C or lower, more preferably 140°C or lower, and even more preferably 135°C or lower, from the viewpoint of further improving the balance of heat resistance, transparency, mechanical properties, rigidity, fluidity, and moldability. If the melting point of the polyethylene resin is above the lower limit, heat fusion between the outermost polyethylene resin layers in the packaging 10 can be further suppressed. Furthermore, if the melting point of the polyethylene resin is below the upper limit, interlayer strength, fluidity, and moldability can be improved.

[0027] The density of the polyethylene resin described above is preferably 920 kg / m³, from the viewpoint of further improving the balance of heat resistance, transparency, mechanical properties, rigidity, fluidity, and moldability. 3 More preferably 923 kg / m³ 3 More preferably 925 kg / m 3 The above, and preferably 970 kg / m 3 More preferably 965 kg / m 3 More preferably, 960 kg / m 3 The following is particularly preferable: 950 kg / m 3 The following applies. In this embodiment, the density of the polyethylene resin can be measured in accordance with JIS K 7112 (1999). If the density of the polyethylene resin is above the lower limit, heat fusion between the outermost polyethylene resin layers in the packaging 10 can be further suppressed. Furthermore, if the density of the polyethylene resin is below the upper limit, interlayer strength, fluidity, and moldability can be improved.

[0028] According to ASTM D1238, the melt flow rate (MFR) of the polyethylene resin, measured under conditions of 190°C and a 2.16 kg load, is preferably 0.5 g / 10 min or more, more preferably 1 g / 10 min or more, and even more preferably 2 g / 10 min or more, from the viewpoint of fluidity and moldability, and preferably 30 g / 10 min or less, more preferably 20 g / 10 min or less, and even more preferably 10 g / 10 min or less, from the viewpoint of further stabilizing moldability.

[0029] The method for producing the polyethylene resin described above is not particularly limited and can be produced by known methods. Furthermore, commercially available polyethylene may be used.

[0030] (Other ingredients) The polyethylene resin composition according to this embodiment may optionally contain various additives such as tackifiers, 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, to the extent that they do not impair the purpose of this embodiment.

[0031] (Method for preparing polyethylene resin compositions) The polyethylene resin composition according to this embodiment can be prepared, for example, by mixing or melting / kneading each component using methods / appliances such as dry blending, tumbler mixer, Banbury mixer, single-screw extruder, twin-screw extruder, high-speed twin-screw extruder, and hot roll.

[0032] [Heat seal layer] In order to provide heat-sealability, the packaging film according to this embodiment preferably has a heat-seal layer on at least a portion of one side of the polyethylene resin layer. The heat-seal layer may be provided only in the area of ​​the packaging film according to this embodiment that is to be heat-sealed, or it may be provided on the entire surface of one side of the polyethylene resin layer.

[0033] In the packaging film according to this embodiment, the thickness of the heat seal layer is preferably 0.1 μm or more and 200 μm or less, more preferably 0.2 μm or more and 170 μm or less, even more preferably 0.5 μm or more and 150 μm or less, and particularly preferably 1 μm or more and 120 μm or less. By ensuring that the thickness of the heat-seal layer is equal to or greater than the above lower limit, the heat-sealability of the packaging film can be improved. Furthermore, by keeping the thickness of the heat seal layer below the above upper limit, the fusion of the outermost layer during heat sealing can be particularly suppressed. Generally, the thicker the heat seal layer, the higher the temperature required for sealing.

[0034] In the packaging film according to this embodiment, the heat-seal layer provided on one side is preferably a single layer. This simplifies the manufacturing process of the packaging film, that is, the manufacturing process of the packaged body 10 according to this embodiment.

[0035] Furthermore, the heat seal layer may be formed by stretching simultaneously with the film, which is in its pre-stretched state as a polyethylene resin layer. This allows for the production of a packaging film using a molding method such as co-extrusion, i.e., a laminated film produced in a single molding process. Thus, the manufacturing process of the packaging film, i.e., the manufacturing process of the packaging body 10 according to this embodiment, can be simplified. Therefore, the heat seal layer may be uniaxially or biaxially stretched.

[0036] (Polyolefin) The heat seal layer according to this embodiment is composed of, for example, a polyolefin-based resin composition containing a polyolefin. Examples of polyolefins constituting the heat seal layer include homopolymers or copolymers of α-olefins such as ethylene, propylene, butene-1, hexene-1, 4-methylpentene-1, and octene-1; polyethylene resins such as high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear polyethylene, and ultra-high molecular weight polyethylene; polypropylene; propylene-α-olefin random copolymer; ethylene-vinyl acetate copolymer (EVA); and ionomer resins. Among these, polyethylene resin is preferred as the polyolefin constituting the heat seal layer, due to its superior balance of recyclability, adhesion to the polyethylene resin layer, and heat sealability. As a result, the packaging is composed almost entirely of a single material (monomaterial), making it easier to separate the materials constituting the packaging 10 and improving the recyclability of the packaging 10.

[0037] (Polyethylene resin) Examples of polyethylene resins that constitute the heat seal layer according to this embodiment include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and ultra-high molecular weight polyethylene. Among these, low-density polyethylene and linear low-density polyethylene are preferred, and linear low-density polyethylene is more preferred. One type of polyethylene may be used, or two or more types may be used in combination.

[0038] The melting point of the polyethylene resin described above is preferably in the range of 90°C or higher, more preferably 95°C or higher, and more preferably 140°C or lower, and more preferably 120°C or lower. If the melting point of the polyethylene resin is above the lower limit mentioned above, stickiness on the surface of the heat seal layer can be suppressed, and the blocking resistance of the packaging film can be improved. Furthermore, if the melting point of the polyethylene resin is below the above upper limit, the heat-sealability of the packaging film can be improved.

[0039] According to ASTM D1238, the melt flow rate (MFR) of the polyethylene resin, measured under conditions of 190°C and a 2.16 kg load, is preferably 0.5 g / 10 min or more, more preferably 1 g / 10 min or more, and even more preferably 2 g / 10 min or more, from the viewpoint of fluidity and moldability, and preferably 30 g / 10 min or less, more preferably 20 g / 10 min or less, and even more preferably 10 g / 10 min or less, from the viewpoint of further stabilizing moldability.

[0040] The method for producing the polyethylene resin described above is not particularly limited and can be produced by known methods. Furthermore, commercially available polyethylene may be used.

[0041] The polyolefin resin content in the polyolefin resin composition according to this embodiment (i.e., in the heat seal layer) is preferably 90% to 100% by mass, more preferably 95% to 100% by mass, even more preferably 98% to 100% by mass, and particularly preferably 99% to 100% by mass, when the total polyolefin resin composition is considered to be 100% by mass. This allows for a better balance of recyclability, adhesion to the polyethylene resin layer, heat sealability, etc.

[0042] (Other ingredients) The polyolefin resin composition constituting the heat seal layer according to this embodiment may optionally 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, to the extent that they do not impair the purpose of this embodiment. On the other hand, from the viewpoint of monomaterialization, it is preferable that the polyolefin resin composition substantially does not contain these various additives.

[0043] (Method for preparing polyolefin resin compositions) The polyolefin resin composition according to this embodiment can be prepared by mixing or melting / kneading each component using a dry blender, tumbler mixer, Banbury mixer, single-screw extruder, twin-screw extruder, high-speed twin-screw extruder, hot roll, etc.

[0044] <Manufacturing method for packaging film> The packaging film according to this embodiment can be obtained, for example, by co-extruding a polyethylene resin composition for forming a polyethylene resin layer and a polyolefin resin composition for forming a heat seal layer into a film, and then uniaxially or biaxially stretching the resulting laminated film using a known stretched film manufacturing method. The molding apparatus and molding conditions are not particularly limited, and conventionally known molding apparatuses and molding conditions can be adopted. As the molding apparatus, a multi-layer T-die extruder or a multi-layer inflation molding machine can be used. The conditions for biaxial stretching can be, for example, the manufacturing conditions of known stretched films. The manufacturing conditions of the stretched film are not particularly limited, and for example, the following conditions can be mentioned. Extrusion setting temperature: 190 - 250 °C, processing speed: 20 - 60 m / min Longitudinal stretching temperature: 100 - 130 °C Longitudinal stretching ratio: 3.5 - 7.5 times Transverse stretching temperature: 100 - 150 °C Transverse stretching ratio: 4 - 12 times In addition, the packaging film according to the present embodiment can also be obtained by dry lamination in which only the outermost layer that has been uniaxially or biaxially stretched or a polyethylene resin layer including the outermost layer and a heat-sealing layer are separately molded and laminated with an adhesive or the like. Furthermore, the packaging film according to the present embodiment can also be obtained by molding the resin of the heat-sealing layer by extrusion lamination or the like on a uniaxially or biaxially stretched polyethylene resin layer.

[0045] As described above, the embodiments of the present invention have been described with reference to the drawings, but these are examples of the present invention, and various configurations other than the above can also be adopted.

Examples

[0046] Hereinafter, the present embodiment will be described in detail with reference to Examples and Comparative Examples. Note that the present embodiment is not limited to the descriptions of these Examples.

[0047] 1. Raw materials The raw materials used in the Examples and Comparative Examples are shown below. (1) Polyethylene resin PE1: Polyethylene (MFR: 0.8 g / 10 min, density: 926 kg / m 3 , melting point: 124 °C) PE2: Polyethylene (MFR: 2.8g / 10 min, Density: 942kg / m³) 3 (Melting point: 129℃) PE3: Polyethylene (MFR: 1.8g / 10 min, Density: 927kg / m³) 3 (Melting point: 127℃) PE4: Polyethylene (MFR: 3.8g / 10 min, Density: 918kg / m³) 3 (Melting point: 116℃) PE5: Polyethylene (MFR: 1.1g / 10 min, Density: 950kg / m³) 3 (Melting point: 132℃)

[0048] 2. Measurement and Evaluation Methods (1) Polyethylene resin MFR Measurements were taken in accordance with ASTM D1238, under conditions of 190°C and a 2.16 kg load.

[0049] (2) Melting point of polyethylene resin The melting point was defined as the temperature of the maximum melting peak in the DSC (Differential Scanning Calorimeter) curve of the polyethylene resin, obtained using DSC. Specifically, the melting point was defined as the temperature of the maximum melting peak in the DSC curve of the 2nd run, when the following 1st and 2nd runs were performed. 1st run: Heat to 200°C at a rate of 10°C / min, hold for 10 minutes, then cool to -50°C at a rate of 10°C / min. 2nd run: After the 1st run is complete, continue increasing the temperature to 200°C at a rate of 10°C / min.

[0050] (3) Density of polyethylene resin The density of polyethylene resin was measured in accordance with JIS K 7112 (1999).

[0051] (4) Evaluation of thermal fusion properties A laminated film was obtained by heat-sealing the outermost layers of two 15mm wide packaging films together at 130°C, a pressure of 2.0 kgf, and a sealing time of 1 second. Next, the two packaging films were peeled apart at a width of 15mm, a 180-degree peel angle, and a peeling speed of 300 mm / min, and the peel strength at that time was defined as the heat seal strength. Next, the heat-sealability of the packaging film was evaluated according to the following criteria. ◎(Very Good): Heat seal strength is less than 2.0N / 15mm ○ (Good): Heat seal strength of 2.0N / 15mm or more and less than 5.0N / 15mm △(Bad): Heat seal strength is between 5.0N / 15mm and less than 10.0N / 15mm. × (Very Bad): Heat seal strength is 10.0N / 15mm or higher

[0052] (5) Presence or absence of whitening (transparency) The packaging film was visually inspected, and the following criteria were used for evaluation. 〇 (Good): Sufficiently transparent; no issues with visibility of the packaged contents as a packaging film. ×(Bad): The matte finish makes it difficult to see the contents of the package when used as packaging film.

[0053] [Examples 1-13] Packaging films were produced by co-extruding each layer according to the layer configuration shown in Table 1, and then stretching them. The heat-seal properties were then evaluated. The molding machines used are as follows: Multilayer extrusion molding machine: 260mm wide multilayer T-die extrusion molding machine (L / D=27, manufactured by Screw Seiki Co., Ltd.) Furthermore, the extension ratio was determined as follows: Examples 1, 2, 4: Biaxial stretching of 4.0 to 7.5 times vertically and 7.5 to 14 times horizontally. Example 3: Uniaxial stretching 8 to 14 times horizontally

[0054] [Comparative Example 1] Packaging films were prepared by co-extruding each layer with the layer configuration shown in Table 1 (no stretching treatment was performed in Comparative Example 1). The heat-seal properties were then evaluated. The molding machines used are as follows: Multilayer extrusion machine: Multilayer T-die extrusion machine (L / D=30)

[0055] [Table 1]

[0056] This application claims priority based on Japanese Patent Application No. 2019-171374, filed on September 20, 2019, and incorporates all of its disclosures herein. [Explanation of symbols]

[0057] 1 package 2 Heat seal layers 3 bottom 4. Polyethylene resin layer 10 Packaging

Claims

[Claim 1] A package made of packaging film, The outermost layer is a polyethylene resin layer. The polyethylene resin layer is biaxially stretched, The aforementioned packaging is a packaging bag, The polyethylene resin constituting the polyethylene resin layer has a melting point of 100°C or higher and 150°C or lower. The innermost layer of the packaging has a heat-seal layer, The heat seal layer contains a polyethylene resin, The melting point of the polyethylene resin constituting the heat seal layer is 90°C or higher and 140°C or lower. When the entirety of the aforementioned packaging is considered to be 100% by mass, 90% or more by mass of the packaging is polyethylene resin. The polyethylene resin constituting the polyethylene resin layer is a combination of two or more types of polyethylene resins. A packaging body in which the polyethylene resin constituting the polyethylene resin layer falls under at least one of the following (ii) to (iii). (ii) Combine polyethylene resins with densities differing by 10 kg / m³ or more. In this case, the ratio of the two resins should be the same by mass, or the resin with the lower density should be used in greater proportion. (iii) Combine polyethylene resins with melting points that differ by 1°C or more. In this case, the ratio of the two resins should be the same by mass, or the resin with the lower melting point should be used in greater proportion.

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