Film for sealant layer, heat-resistant film and packaging bag

Abstract

To provide a film for a sealant layer having a biomass layer containing burned powder of shells, a heat-resistant film which uses the same and has heat resistance enabling boil sterilization, or heat resistance enabling not only boil sterilization but also retort sterilization, and a packaging bag using the same.SOLUTION: A film for a sealant layer includes a biomass layer containing burned powder of shells in a linear low-density polyethylene resin, and a linear low-density polyethylene resin layer located on at least one surface of the biomass layer, wherein a percentage content of the burned powder of shells in the film for the sealant layer is within a range of 5 mass% to 30 mass%, and the heat-resistant film has a laminated structure including a laminated structure in which the film for the sealant layer is a sealant layer, and a polyethylene terephthalate resin layer, a metal thin film layer and a polyethylene terephthalate resin layer are laminated in this order on one surface of the sealant layer and on the linear low-density polyethylene resin layer surface.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a film for a sealant layer, a heat-resistant film using the same, and a packaging bag, and in particular to a film for a sealant layer having a biomass layer, and a heat-resistant film and packaging bag that are biomass films but have heat resistance that allows them to be boiled or retort sterilized. [Background technology]

[0002] Synthetic resin films have been used for a variety of purposes, including food packaging, housing products, electronic products, construction materials, and more. Food packaging is often in contact with humans and may be a source of infection for pathogens and bacteria, so antibacterial films using various antibacterial and antifungal agents have been proposed. In particular, biomass films using powdered burnt shells have attracted attention from the perspective of effective use of biomass resources that are industrial waste.

[0003] As a biomass film using such baked shell powder, for example, a biomass film containing baked scallop shell powder in a resin has been proposed (Patent Document 1, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6522618 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional biomass films containing baked shell powder in the resin as described above have a problem in that they do not have sufficient heat resistance and cannot be used even in boiling sterilization, which is moist heat sterilization at temperatures below 100° C. For this reason, there has been a demand for the development of a biomass film containing baked shell powder that is heat-resistant and can be used in boiling sterilization, and also a heat-resistant film that can be used not only in boiling sterilization but also in retort sterilization, which involves pressurizing and heating at temperatures above 100° C.

[0006] The present invention has been made in response to the above-mentioned demand, and has an objective of providing a film for a sealant layer having a biomass layer containing baked shell powder, a heat-resistant film using the same that has heat resistance allowing boiling sterilization, or heat resistance allowing not only boiling sterilization but also retort sterilization, and a packaging bag using the same. [Means for solving the problem]

[0007] In order to achieve the above object, the film for a sealant layer of the present invention comprises a biomass layer in which baked shell powder is contained in a linear low-density polyethylene resin, and a linear low-density polyethylene resin layer located on at least one side of the biomass layer, and is configured such that the content of the baked shell powder in the film for a sealant layer is in the range of 5% by mass to 30% by mass.

[0008] The heat-resistant film of the present invention has a laminated structure in which a sealant layer is laminated on one side of the sealant layer with a polyethylene terephthalate resin layer, a metal thin film layer, and a polyethylene terephthalate resin layer in this order, the sealant layer being the film for sealant layer described above, and the polyethylene terephthalate resin layer being located on the linear low-density polyethylene resin layer surface of the film for sealant layer. In another embodiment of the present invention, the sealant layer is configured to contain 10% to 50% by mass of plant-derived polyethylene resin and 5% to 30% by mass of the baked shell powder.

[0009] In another embodiment of the present invention, a laminate structure is provided in which a sealant layer is provided and, on one side of the sealant layer, a metal thin film layer, a stretched polyamide resin layer, and a polyethylene terephthalate resin layer are laminated in this order, the sealant layer being the above-mentioned film for sealant layer, and the metal thin film layer is located on the surface of the linear low-density polyethylene resin layer of the film for sealant layer.

[0010] In another embodiment of the present invention, the oxygen permeability is 15 ml / m 2 ·day or less, and the water vapor permeability is 5g / m 2 The configuration is such that the number of days is less than or equal to 1.

[0011] The packaging bag of the present invention is constructed using any one of the above heat-resistant films. Effect of the Invention

[0012] The film for a sealant layer according to the present invention, the heat-resistant film using the same, and the packaging bag using the same are as described above, and have the effect of having heat resistance sufficient for use in boiling sterilization, or heat resistance sufficient for use in retort sterilization, which involves pressurization and heating at temperatures exceeding 100°C. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] [Sealant layer film] The film for a sealant layer of the present invention is characterized by comprising a biomass layer in which a powder of baked shells is contained in a linear low-density polyethylene resin, and a linear low-density polyethylene resin layer located on at least one surface of the biomass layer, and the content of the baked shell powder in the film for a sealant layer is in the range of 5% by mass to 30% by mass. Therefore, the film for a sealant layer of the present invention may be either a two-layer structure in which a linear low-density polyethylene resin layer is located on one surface of the biomass layer, or a three-layer structure in which linear low-density polyethylene resin layers are located on both surfaces of the biomass layer.

[0014] Such a film for a sealant layer can be formed, for example, by extrusion molding using a linear low-density polyethylene resin containing baked shell powder and a linear low-density polyethylene resin not containing baked shell powder. In order to increase the content of baked shell powder in the film for a sealant layer, the biomass layer constituting the above-mentioned two-layered film for a sealant layer and the three-layered film for a sealant layer may be two or more layers of linear low-density polyethylene resin containing baked shell powder to form a biomass layer with a large layer thickness.

[0015] The linear low-density polyethylene resin constituting the biomass layer of the film for a sealant layer of the present invention has a density of 0.90 g / cm 3 ~0.97g / cm 3 The density range of 0.90 g / cm3 can be used. 3 If it is less than 0.97 g / cm, blocking resistance may decrease. 3 If the content exceeds 100%, the dispersibility of the powder of the burnt shell may decrease. From the viewpoints of seal strength and odor, it is preferable to use such a linear low-density polyethylene resin produced by using a metallocene catalyst.

[0016] The linear low density polyethylene resin constituting the linear low density polyethylene resin layer of the film for sealant layer of the present invention has a density of 0.90 g / cm 3 ~0.97g / cm 3 The density range of 0.90 g / cm 3 If it is less than 0.97 g / cm, blocking resistance may decrease. 3 If the content exceeds 100%, the dispersibility of the powder of the burnt shell may decrease. From the viewpoints of seal strength and odor, it is preferable to use such a linear low-density polyethylene resin produced by using a metallocene catalyst.

[0017] The powder of calcined shells constituting the biomass layer of the film for sealant layer of the present invention is a powder obtained by calcining crushed shells and then hydrating them. Shells to be used include scallop shells, surf clam shells, abalone shells, sea urchin shells, turban shells, oyster shells, clam shells, mussel shells, and Japanese medaka shells, with scallop shells being preferred in terms of supply amount, etc.

[0018] The firing temperature of the shells can be 600° C. to 1200° C., preferably 800° C. to 1000° C. The firing time can be set in consideration of the firing temperature, and can be appropriately set within the range of, for example, 1 hour to 3 hours. By such firing, calcium carbonate contained in the shells is converted into calcium oxide.

[0019] In the hydration treatment of the burned shells, water is added to the burned shells (calcium oxide) to cause a hydration reaction, producing calcium hydroxide. The burned shells that have been hydrated and dried are then pulverized to produce powder with an average particle size of 2 μm to 60 μm, preferably 2 μm to 11 μm. A conventionally known pulverizing device can be used for the pulverization treatment. The burned shell powder thus prepared preferably has a surface energy within a predetermined range, which makes the powder of the burned shells well dispersible in the linear low-density polyethylene resin and less likely to aggregate, resulting in good surface smoothness of the biomass layer.

[0020] The average particle size of the baked shell powder can be measured by a laser diffraction method using the values ​​of the particle refractive index and the dispersion medium refractive index.

[0021] The thickness of the biomass layer constituting the film for sealant layer of the present invention can be in the range of 5 μm to 140 μm, preferably 10 μm to 40 μm. If the thickness of the biomass layer is less than 5 μm, poor sealing between the biomass layer and the linear low-density polyethylene resin layer may occur, and if it exceeds 140 μm, poor film formation of the film for sealant layer may occur. The content of the baked shell powder in the biomass layer can be set to be in the range of 5% by mass to 30% by mass, preferably 10% by mass to 30% by mass.

[0022] In addition, the thickness of the linear low-density polyethylene resin layer constituting the sealant layer film of the present invention can be appropriately set according to the thickness of the biomass layer so that the total thickness of the sealant layer film is within the following range.

[0023] The total thickness of the film for a sealant layer of the present invention can be in the range of 30 μm to 150 μm. If the thickness of the film for a sealant layer is less than 30 μm, poor sealing between the film for a sealant layer and other layers may occur in the production of a heat-resistant film using the film for a sealant layer, while if it exceeds 150 μm, poor film formation of the film for a sealant layer may occur.

[0024] [Heat-resistant film] (First aspect) The first embodiment of the heat-resistant film of the present invention has a laminated structure in which a sealant layer is laminated on one side of the sealant layer with a polyethylene terephthalate resin layer, a metal thin film layer, and a polyethylene terephthalate resin layer in this order, the sealant layer being the film for sealant layer of the present invention described above, and the polyethylene terephthalate resin layer being located on the linear low-density polyethylene resin layer side of the film for sealant layer. This provides the effect of having heat resistance sufficient for boiling sterilization despite being a biomass film, or heat resistance sufficient for retort sterilization in which pressurized heating exceeding 100°C is performed, in addition to boiling sterilization.

[0025] The two polyethylene terephthalate resin layers constituting the heat-resistant film of the first embodiment are preferably biaxially stretched polyethylene terephthalate resin films, and the thickness of each polyethylene terephthalate resin layer can be in the range of 9 μm to 16 μm, preferably 9 μm to 12 μm.

[0026] The polyethylene terephthalate resin layer has an oxygen permeability of, for example, 120 ml / m 2 ·day or less, and the water vapor permeability is 9g / m 2 ·day or less. In this case, a polyethylene terephthalate resin film having barrier properties can be used. If the polyethylene terephthalate resin film used does not have sufficient barrier properties, a polyethylene terephthalate resin film on which one or more of aluminum, aluminum oxide, silicon dioxide, etc. are vapor-deposited to impart barrier properties can be used.

[0027] The metal thin film layer constituting the heat-resistant film of the first embodiment of the present invention is a metal foil such as an aluminum foil, etc. The thickness of the metal thin film layer can be in the range of 7 μm to 25 μm, preferably 7 μm to 9 μm.

[0028] The heat-resistant film of the first embodiment can be produced by laminating a polyethylene terephthalate resin film and a metal foil to the film for sealant layer of the present invention using an adhesive by a normal dry lamination method. The heat-resistant film of the first embodiment thus provided with a metal thin film layer has an oxygen permeability of, for example, 15 ml / m 2 ·day or less, and the water vapor permeability is 5g / m 2 The product has excellent barrier properties of less than 1.5 days.

[0029] The heat-resistant film of the first aspect of the present invention may contain a plant-derived polyethylene resin in the sealant layer. In this case, it is suitable that the sealant layer contains 10% to 50% by mass, preferably 10% to 30% by mass of the plant-derived polyethylene resin, and 5% to 30% by mass, preferably 10% to 30% by mass of baked shell powder.

[0030] As the plant-derived polyethylene resin, known plant-derived polyethylene resins can be used.

[0031] The thickness of the heat-resistant film in the first embodiment can be in the range of 55 μm to 175 μm, preferably 60 μm to 80 μm.

[0032] The heat-resistant film of the first aspect of the present invention has a laminated structure including a polyethylene terephthalate resin layer, a metal thin film layer, and a polyethylene terephthalate resin layer laminated on one side of a sealant layer having a biomass layer containing baked shell powder, and a linear low-density polyethylene resin layer constituting the sealant layer, so that the sealant layer has high adhesion with the polyethylene terephthalate resin layer, the metal thin film layer, and the polyethylene terephthalate resin layer, and interlayer peeling is suppressed even under pressurized and heated conditions, resulting in excellent heat resistance. Furthermore, even when the sealant layer and the polyethylene terephthalate resin layer contain plant-derived polyethylene resin, the film has excellent heat resistance and suppresses odor generation.

[0033] (Second aspect) A second embodiment of the heat-resistant film of the present invention has a laminated structure in which a sealant layer is laminated on one side of the sealant layer with a metal thin film layer, a stretched polyamide resin layer, and a polyethylene terephthalate resin layer in this order, the sealant layer being the film for sealant layer of the present invention described above, and the metal thin film layer being located on the linear low-density polyethylene resin layer side of the film for sealant layer. This provides the effect of having heat resistance sufficient for boiling sterilization despite being a biomass film, or heat resistance sufficient for retort sterilization in which pressurized heating exceeding 100°C is performed, in addition to boiling sterilization.

[0034] The polyethylene terephthalate resin layer and the metal thin film layer constituting the heat-resistant film of the second embodiment may be the same as those constituting the heat-resistant film of the first embodiment. The thickness of the polyethylene terephthalate resin layer located at the outermost layer may be in the range of 9 μm to 16 μm, preferably 9 μm to 12 μm, and the thickness of the metal thin film layer may be in the range of 7 μm to 25 μm, preferably 7 μm to 9 μm.

[0035] The polyamide resin constituting the stretched polyamide resin layer of the heat-resistant film of the second embodiment can be appropriately selected depending on the heat resistance required for the heat-resistant film, that is, heat resistance usable for boiling sterilization or heat resistance usable for retort sterilization. The thickness of such a stretched polyamide resin layer can be in the range of 12 μm to 25 μm, preferably 15 μm to 25 μm.

[0036] The stretched polyamide resin layer has an oxygen permeability of, for example, 110 ml / m 2 ·day or less, and the water vapor permeability is 190g / m 2·day or less. In this case, a stretched polyamide resin film having barrier properties can be used. If the stretched polyamide resin film used does not have sufficient barrier properties, one or more of aluminum, aluminum oxide, silicon dioxide, etc. can be vapor-deposited on at least one surface of the stretched polyamide resin film, preferably on the surface on the sealant layer side, in order to impart barrier properties.

[0037] In the present invention, the stretched polyamide resin layer constituting the heat-resistant film of the second embodiment may be formed by using a laminated film obtained by laminating a stretched polyamide resin film on a base film made of a biaxially stretched polyethylene terephthalate resin film, and laminating the stretched polyamide resin film side to adhere to the metal thin film layer. In this case, the thickness of the stretched polyamide resin film constituting the laminated film can be in the range of 12 μm to 25 μm, preferably 15 μm to 25 μm, as described above. By using a laminated film obtained by laminating a stretched polyamide resin film on a base film made of a biaxially stretched polyethylene terephthalate resin film as the stretched polyamide resin layer in this way, the heat-resistant film of the present invention can have heat resistance that allows retort sterilization.

[0038] In addition, as described above, when a laminated film obtained by laminating a stretched polyamide resin film on a base film made of a biaxially stretched polyethylene terephthalate resin film is used to form a stretched polyamide resin layer constituting the heat-resistant film of the second embodiment, the biaxially stretched polyethylene terephthalate resin film (base film) constituting this laminated film constitutes a part of the polyethylene terephthalate resin layer located at the outermost layer of the heat-resistant film of the second embodiment. In this case, the thickness of the biaxially stretched polyethylene terephthalate resin film (base film) constituting the stretched polyamide resin layer of the laminated film can be in the range of 9 μm to 16 μm, preferably 9 μm to 12 μm.

[0039] The thickness of the heat-resistant film in the second embodiment can be in the range of 58 μm to 178 μm, preferably 60 μm to 80 μm.

[0040] The heat-resistant film of the second aspect of the present invention described above has a laminated structure including a metal thin film layer, an oriented polyamide resin layer, and a polyethylene terephthalate resin layer laminated on the surface of the linear low-density polyethylene resin layer constituting the sealant layer, which is one side of the sealant layer having a biomass layer containing baked shell powder. Therefore, the sealant layer has high adhesion to the metal thin film layer, the oriented polyamide resin layer, and the polyethylene terephthalate resin layer, and interlayer delamination is suppressed even under pressurized and heated conditions, resulting in excellent heat resistance.

[0041] [Packaging bag] The packaging bag of the present invention is a bag using any one of the heat-resistant films according to the first to second aspects of the present invention described above.

[0042] The shape of the packaging bag of the present invention is not particularly limited, and examples thereof include standing bags, three-sided bags, palm-shaped bags, gusset bags, box bags, spout bags, and the like.

[0043] The packaging bag of the present invention can be produced by overlapping the heat-resistant film of the present invention so that the sealant layer of the film is on the inside and heat-sealing the overlapped film. To produce the packaging bag of the present invention by heat-sealing, various known methods and devices can be used, and for example, the packaging bag of the present invention can be produced by folding back a long heat-resistant film of the present invention as a raw roll and heat-sealing the overlapped film, or by overlapping two sheets of the heat-resistant film of the present invention cut to a predetermined size and heat-sealing the overlapped film.

[0044] The packaging bag of the present invention is manufactured using the heat-resistant film of the present invention, and therefore, even under pressurized and heated conditions, delamination between layers is suppressed and the bag has excellent heat resistance. Therefore, the products to be packed in the packaging bag include various foods that require retort sterilization. The packaging bag of the present invention can also be used for applications that do not require retort sterilization, and can be used for the purpose of packing products that require the use of a sterilized bag, such as medicines, medical equipment, physicochemical equipment, cosmetics, animal feed, food, and nutritional supplements.

[0045] The above-mentioned embodiments of the film for a sealant layer, the heat-resistant film using the same, and the packaging bag are merely examples, and the present invention is not limited to these embodiments. EXAMPLES

[0046] The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

[0047] [Example 1] (Preparation of baked shell powder) The scallop shells were crushed and then baked at 1000°C for 80 minutes to convert the calcium carbonate contained in the scallop shells into calcium oxide, which was then hydrated to calcium hydroxide, and then crushed by a dry grinding method to prepare a powder of baked shells. The average particle size of this baked shell powder was 8 μm. The average particle size of the baked shell powder was measured by a laser diffraction method using the values ​​of the particle refractive index and the dispersion medium refractive index.

[0048] (Preparation of film for sealant layer) The baked shell powder prepared as described above was mixed and kneaded with a linear low-density polyethylene resin to prepare a biomass resin composition containing baked scallop shell powder.

[0049] This biomass resin composition was melted and extruded through a T-die, and then brought into contact with a forming roll to cool and solidify, producing a 50 μm-thick single-layer film for a sealant layer (sealant layer film sample 1).

[0050] In addition, the above biomass resin composition and linear low-density polyethylene resin were used to produce a two-layered (50 μm thick) film for sealant layer (sealant layer film sample 2) having a 30 μm thick biomass layer and a 20 μm thick linear low-density polyethylene resin layer on one side of the biomass layer by extrusion molding. The biomass layer of this sealant layer film was formed by laminating two 15 μm thick biomass layers to form a 30 μm thick biomass layer.

[0051] Furthermore, the above biomass resin composition and linear low-density polyethylene resin were used to produce a three-layer film for a sealant layer (sealant layer sample 3) having a thickness of 50 μm, which had a biomass layer having a thickness of 20 μm and linear low-density polyethylene resin layers having a thickness of 15 μm positioned on both sides of the biomass layer.

[0052] [Example 2] (Preparation of heat-resistant film) A biaxially oriented polyethylene terephthalate resin film (thickness 12 μm), an aluminum foil (thickness 7 μm), and a biaxially oriented polyethylene terephthalate resin film (thickness 12 μm) were laminated in this order by dry lamination on one side of the film for sealant layer (film sample 1 for sealant layer) having a single layer structure prepared in Example 1. In this way, a heat-resistant film (film sample 1) was prepared in which a polyethylene terephthalate resin layer, a metal thin film layer (aluminum foil), and a polyethylene terephthalate resin layer were laminated in this order on one side of the sealant layer.

[0053] In addition, the above biaxially oriented polyethylene terephthalate resin film, aluminum foil, and biaxially oriented polyethylene terephthalate resin film were laminated by dry lamination in this order on the biomass layer surface of the two-layered film for sealant layer (film sample 2 for sealant layer) produced in Example 1. In this way, a heat-resistant film (film sample 2-1) was produced in which a polyethylene terephthalate resin layer, a metal thin film layer (aluminum foil), and a polyethylene terephthalate resin layer were laminated in this order on one surface of the sealant layer.

[0054] In addition, the biaxially oriented polyethylene terephthalate resin film, aluminum foil, and biaxially oriented polyethylene terephthalate resin film were laminated in this order by dry lamination on the linear low-density polyethylene resin layer surface of the two-layered film for sealant layer (film sample 2 for sealant layer) produced in Example 1. In this way, a heat-resistant film (film sample 2-2) was produced in which a polyethylene terephthalate resin layer, a metal thin film layer (aluminum foil), and a polyethylene terephthalate resin layer were laminated in this order on one side of the sealant layer.

[0055] Furthermore, the biaxially oriented polyethylene terephthalate resin film, aluminum foil, and biaxially oriented polyethylene terephthalate resin film were laminated in this order by dry lamination on one side of the three-layered film for sealant layer (film sample 3 for sealant layer) prepared in Example 1. This produced a heat-resistant film (film sample 3) in which a polyethylene terephthalate resin layer, a metal thin film layer (aluminum foil), and a polyethylene terephthalate resin layer were laminated in this order on one side of the sealant layer.

[0056] (Making packaging bags) Four types of three-sided bags (bag samples 1, 2-1, 2-2, and 3) were produced using the four types of heat-resistant films (film samples 1, 2-1, 2-2, and 3) produced as described above.

[0057] (evaluation) The four types of packaging bags (bag samples 1, 2-1, 2-2, and 3) prepared as described above were subjected to the following heat resistance (boil sterilization) test and heat resistance (retort sterilization) test, and the results are shown in Table 1 below. (Heat resistance (boiling sterilization) test) The packaging bag was filled with water, sealed, and sterilized by boiling at 100°C for 30 minutes. The condition of the packaging bag was then visually observed and evaluated according to the following criteria. (Evaluation Criteria) ○: No delamination of the heat-resistant film occurs, and the laminate strength is good. No deterioration was observed and heat resistance was good. ×: No delamination of the heat-resistant film occurs, but the laminate The strength of the material was reduced, making it unsuitable for practical use. (Heat resistance (retort sterilization) test) The packaging bag was filled with water, sealed, and subjected to retort sterilization at 120°C for 30 minutes. The condition of the packaging bag was then visually observed and evaluated according to the following criteria. (Evaluation Criteria) ◯: No delamination of the heat-resistant film was observed, and the heat resistance was good. ×: Interlayer peeling of the heat-resistant film was observed, and the heat resistance was poor.

[0058] [Table 1]

[0059] As shown in Table 1, it was confirmed that the bag samples 2-2 and 2-3 have excellent heat resistance that allows retort sterilization. In contrast, the bag samples 1 and 2-1 showed a decrease in laminate strength after boiling sterilization, and were confirmed to have poor heat resistance.

[0060] [Example 3] (Preparation of film for sealant layer) Similar to the three types of films for sealant layers in Example 1 (sealant layer film samples 1 to 3), three types of films for sealant layers (sealant layer film samples 4 to 6) were produced.

[0061] (Preparation of heat-resistant film) Next, an aluminum foil (thickness 7 μm), a single-layered stretched polyamide resin film A (thickness 15 μm), and a biaxially stretched polyethylene terephthalate resin film (thickness 12 μm) were laminated in this order on one side of the prepared single-layered film for sealant layer (film sample 4 for sealant layer). This produced a heat-resistant film (film sample 4) in which a metal thin film layer (aluminum foil), a stretched polyamide resin layer, and a polyethylene terephthalate resin layer were laminated in this order on one side of the sealant layer.

[0062] In addition, the above-mentioned aluminum foil, stretched polyamide resin film A, and biaxially stretched polyethylene terephthalate resin film were laminated in this order by dry lamination on the biomass layer surface of the two-layered film for sealant layer (film sample 5 for sealant layer) prepared as described above. In this way, a heat-resistant film (film sample 5-1) was produced in which a metal thin film layer (aluminum foil), a stretched polyamide resin layer, and a polyethylene terephthalate resin layer were laminated in this order on one side of the sealant layer.

[0063] In addition, the above-mentioned aluminum foil, stretched polyamide resin film A, and biaxially stretched polyethylene terephthalate resin film were laminated in this order by dry lamination on the linear low-density polyethylene resin layer surface of the two-layered film for sealant layer (film sample 5 for sealant layer) prepared as described above. In this way, a heat-resistant film (film sample 5-2) was produced in which a metal thin film layer (aluminum foil), a stretched polyamide resin layer, and a polyethylene terephthalate resin layer were laminated in this order on one side of the sealant layer.

[0064] Furthermore, the above aluminum foil, stretched polyamide resin film A, and biaxially stretched polyethylene terephthalate resin film were laminated in this order by dry lamination on one side of the three-layered film for sealant layer (film sample 6 for sealant layer) prepared as above, thereby producing a heat-resistant film (film sample 6) in which a metal thin film layer (aluminum foil), a stretched polyamide resin layer, and a polyethylene terephthalate resin layer were laminated in this order on one side of the sealant layer.

[0065] (Making packaging bags) Four types of three-sided bags (bag samples 4, 5-1, 5-2, and 6) were produced in the same manner as in Example 1 using the four types of heat-resistant films (film samples 4, 5-1, 5-2, and 6) produced as described above.

[0066] (evaluation) The four types of packaging bags (bag samples 4, 5-1, 5-2, and 6) prepared as described above were subjected to heat resistance (boil sterilization) tests and heat resistance (retort sterilization) tests in the same manner as in Example 2, and the results are shown in Table 2 below.

[0067] [Table 2]

[0068] As shown in Table 2, it was confirmed that the bag sample 6 had excellent heat resistance that allowed for retort sterilization. Also, it was confirmed that the bag sample 5-2 had excellent heat resistance that allowed for boiling sterilization. In contrast, the bag samples 4 and 5-1 showed a decrease in laminate strength after boiling sterilization, and were confirmed to have poor heat resistance.

[0069] [Example 4] (Preparation of film for sealant layer) Similar to the three types of films for sealant layers in Example 1 (sealant layer film samples 1 to 3), three types of films for sealant layers (sealant layer film samples 7 to 9) were produced.

[0070] (Preparation of heat-resistant film) Next, an aluminum foil (thickness 7 μm), a stretched polyamide resin film B (thickness 27 μm), and a biaxially stretched polyethylene terephthalate resin film (thickness 12 μm) were laminated in this order by dry lamination on one side of the film for sealant layer (film sample 7 for sealant layer) having a single layer structure prepared as described above. This produced a heat-resistant film (film sample 7) in which a metal thin film layer (aluminum foil), a stretched polyamide resin layer, and a polyethylene terephthalate resin layer were laminated in this order on one side of the sealant layer.

[0071] The stretched polyamide resin film B used above is a laminated film in which a stretched polyamide resin film (thickness 15 μm) is laminated to a base film made of a biaxially stretched polyethylene terephthalate resin film (thickness 12 μm), and the stretched polyamide resin film surface was laminated to an aluminum foil. The total thickness of the polyethylene terephthalate resin layer made of the base film (biaxially stretched polyethylene terephthalate resin film) constituting the above stretched polyamide resin film and the laminated biaxially stretched polyethylene terephthalate resin film was 24 μm.

[0072] In addition, the above-mentioned aluminum foil, stretched polyamide resin film B, and biaxially stretched polyethylene terephthalate resin film were laminated in this order by dry lamination on the biomass layer surface of the two-layered film for sealant layer (film sample 8 for sealant layer) prepared as described above. In this way, a heat-resistant film (film sample 8-1) was produced in which a metal thin film layer (aluminum foil), a stretched polyamide resin layer, and a polyethylene terephthalate resin layer were laminated in this order on one side of the sealant layer.

[0073] In addition, the above-mentioned aluminum foil, stretched polyamide resin film B, and biaxially stretched polyethylene terephthalate resin film were laminated in this order by dry lamination on the linear low-density polyethylene resin layer surface of the two-layered film for sealant layer (film sample 8 for sealant layer) prepared as described above. In this way, a heat-resistant film (film sample 8-2) was produced in which a metal thin film layer (aluminum foil), a stretched polyamide resin layer, and a polyethylene terephthalate resin layer were laminated in this order on one side of the sealant layer.

[0074] Furthermore, the above aluminum foil, stretched polyamide resin film B, and biaxially stretched polyethylene terephthalate resin film were laminated in this order by dry lamination on one side of the three-layered film for sealant layer (film sample 9 for sealant layer) prepared as above, thereby producing a heat-resistant film (film sample 9) in which a metal thin film layer (aluminum foil), a stretched polyamide resin layer, and a polyethylene terephthalate resin layer were laminated in this order on one side of the sealant layer.

[0075] (Making packaging bags) Four types of three-sided bags (bag samples 7, 8-1, 8-2, and 9) were produced in the same manner as in Example 1 using the four types of heat-resistant films (film samples 7, 8-1, 8-2, and 9) produced as described above.

[0076] (evaluation) The four types of packaging bags (bag samples 7, 8-1, 8-2, and 9) prepared as described above were subjected to heat resistance (boil sterilization) tests and heat resistance (retort sterilization) tests in the same manner as in Example 2, and the results are shown in Table 3 below.

[0077] [Table 3]

[0078] As shown in Table 3, it was confirmed that the bag samples 8-2 and 9 had excellent heat resistance that allowed them to be sterilized by retort. In contrast, the bag samples 7 and 8-1 showed a decrease in laminate strength after boiling sterilization, and were confirmed to have poor heat resistance. [Industrial Applicability]

[0079] The heat-resistant films and packaging bags using the sealant layer film of the present invention have the advantage that, despite being biomass films and biomass bags, they have excellent heat resistance and can be boiled or retorted sterilized, and can be used in a variety of applications where heat resistance is required.

Claims

1. A film for a sealant layer comprising: a biomass layer in which a powder of baked shells is contained in a linear low-density polyethylene resin; and a linear low-density polyethylene resin layer located on at least one side of the biomass layer, wherein the content of the baked shell powder in the film for a sealant layer is in the range of 5% by mass to 30% by mass.

2. A heat-resistant film having a laminated structure comprising a sealant layer and, on one side of the sealant layer, a polyethylene terephthalate resin layer, a metal thin film layer, and a polyethylene terephthalate resin layer, in that order, the sealant layer being the film for a sealant layer described in claim 1, and the polyethylene terephthalate resin layer being located on the linear low-density polyethylene resin layer surface of the film for a sealant layer.

3. The heat-resistant film according to claim 2, characterized in that the sealant layer contains a plant-derived polyethylene resin in the range of 10% by mass to 50% by mass and a powder of the baked shell in the range of 5% by mass to 30% by mass.

4. A heat-resistant film having a laminated structure comprising a sealant layer and, on one side of the sealant layer, a metal thin film layer, a stretched polyamide resin layer, and a polyethylene terephthalate resin layer, in that order, the sealant layer being the film for a sealant layer described in claim 1, and the metal thin film layer being located on the linear low-density polyethylene resin layer surface of the film for a sealant layer.

5. Oxygen permeability is 15ml / m ２ day or less, and the water vapor permeability is 5 g / m ２ The heat-resistant film according to any one of claims 2 to 4, wherein the heat-resistant film has a heat resistance of 0.05 -day or less.

6. A packaging bag comprising the heat-resistant film according to any one of claims 2 to 4.

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