Heat-resistant film and packaging bag

Abstract

To provide a heat-resistant film which is a biomass film containing burned powder of shells, and has excellent 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 heat resistant film has a laminated structure including a sealant layer having 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, and a stretched polyamide resin layer located on a surface on one side of the sealant layer and on the linear low-density polyethylene resin layer surface, wherein a percentage content of the burned powder of shells in the sealant layer is within a range of 5 mass% to 30 mass%.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a heat-resistant film and a packaging bag using the same, and more particularly to a heat-resistant film and a packaging bag having heat resistance that allows boiling sterilization or retort sterilization. [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 germs, 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). [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 have the problem 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 need 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 pressurized heating at temperatures above 100° C.

[0006] The present invention has been made in response to the above-mentioned demand, and an object of the present invention is to provide a heat-resistant film that is a biomass film containing baked shell powder and has excellent heat resistance that allows for boiling sterilization, or excellent heat resistance that allows for retort sterilization in addition to boiling sterilization, and a packaging bag using the same. [Means for solving the problem]

[0007] In order to achieve the above object, the heat-resistant film of the present invention has a laminated structure including a sealant layer and a stretched polyamide resin layer located on one side of the sealant layer, the sealant layer having 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, the content of the baked shell powder in the sealant layer being in the range of 5% by mass to 30% by mass, and the stretched polyamide resin layer being located on the linear low-density polyethylene resin layer side of the sealant layer.

[0008] In another embodiment of the present invention, a polyethylene terephthalate resin layer is located on the surface of the stretched polyamide resin layer opposite to the surface on which the sealant layer is located, and the sealant layer contains 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 metal thin film layer and a polyethylene terephthalate resin layer are laminated in this order on the surface of the stretched polyamide resin layer opposite to the surface on which the sealant layer is located, and a polyethylene terephthalate resin layer is interposed between the stretched polyamide resin layer and the metal thin film layer.

[0010] In another embodiment of the present invention, the oxygen permeability is 140 ml / m 2 ·day or less, and water vapor permeability is 50g / 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 heat-resistant film of the present invention is as described above, and while being a biomass film, has heat resistance that allows it to be used in boiling sterilization, or has heat resistance that allows it to be used not only in boiling sterilization but also in retort sterilization involving pressurized heating at above 100°C.Furthermore, the packaging bag of the present invention has the effect of being usable in boiling sterilization, or has heat resistance that allows it to be used not only in boiling sterilization but also in retort sterilization involving pressurized heating at above 100°C. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] [Heat-resistant film] (First aspect) The first embodiment of the heat-resistant film of the present invention is a laminated structure including a sealant layer and a stretched polyamide resin layer located on one side of the sealant layer, the sealant layer having a biomass layer containing a powder of baked shells 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, the content of the baked shell powder in the sealant layer is in the range of 5% by mass to 30% by mass, and the stretched polyamide resin layer is located on the linear low-density polyethylene resin layer side of the sealant layer. This provides an effect that the film has heat resistance sufficient for boiling sterilization despite being a biomass film, or has heat resistance sufficient for retort sterilization in which pressure and heat exceeding 100°C are applied, in addition to boiling sterilization.

[0014] The sealant layer constituting the heat-resistant film of the present invention may be either a two-layer structure in which a linear low-density polyethylene resin layer is located on one side of the biomass layer, or a three-layer structure in which linear low-density polyethylene resin layers are located on both sides of the biomass layer. Such a sealant layer can be formed by extrusion molding, for example, 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 sealant layer, and therefore the content of baked shell powder in the heat-resistant film, the biomass layer constituting the above two-layer sealant layer or three-layer 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 that constitutes the biomass layer of the sealant layer 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 sealant layer 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.

[0017] The fired shell powder constituting the biomass layer of the sealant layer is a powder obtained by firing crushed shells and then hydrating them. Examples of shells that can be used include scallop shells, surf clam shells, abalone shells, turban shells, oyster shells, clam shells, mussel shells, and Japanese medaka shells. From the viewpoint of the supply amount, etc., scallop shells are preferred.

[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 is 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 sealant layer 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, the biomass layer and the linear low-density polyethylene resin layer may be separated from each other. If the thickness exceeds 140 μm, poor sealing may occur, and if the thickness exceeds 140 μm, poor film formation of the sealant layer may occur. The content of the fired 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] The thickness of the linear low-density polyethylene resin layer constituting the sealant layer can be appropriately set according to the thickness of the biomass layer so that the thickness of the sealant layer falls within the following range.

[0023] The thickness of the sealant layer of the two-layer structure or three-layer structure constituting the heat-resistant film of the present invention can be in the range of 30 μm to 150 μm. If the thickness of the sealant layer is less than 30 μm, poor sealing between the sealant layer and the stretched polyamide resin layer may occur, and if it exceeds 150 μm, poor film formation of the sealant layer may occur.

[0024] The polyamide resin constituting the stretched polyamide resin layer of the heat-resistant film of the present invention 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.

[0025] 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.

[0026] The thickness of the heat-resistant film of the first embodiment can be in the range of 42 μm to 162 μm, preferably 50 μm to 80 μm. The heat-resistant film of the first embodiment has an oxygen permeability of 140 ml / m 2 ·day or less, and water vapor permeability is 50g / m 2 ·day or less.

[0027] The heat-resistant film of the first aspect of the present invention described above has a laminated structure including an oriented polyamide resin layer located on one side of a sealant layer having a biomass layer containing baked shell powder, on the surface of the linear low-density polyethylene resin layer constituting the sealant layer. Therefore, adhesion between the sealant layer and the oriented polyamide resin layer is high, interlayer delamination is suppressed even under pressurized and heated conditions, and the heat resistance is excellent.

[0028] (Second aspect) The second embodiment of the heat-resistant film of the present invention has a laminated structure including a sealant layer, a stretched polyamide resin layer on one side of the sealant layer, and a polyethylene terephthalate resin layer on the side opposite to the side on which the sealant layer is located, the sealant layer having a biomass layer containing a powder of baked shells in a linear low-density polyethylene resin and a linear low-density polyethylene resin layer on at least one side of the biomass layer, and the stretched polyamide resin layer is located on the linear low-density polyethylene resin layer side of the sealant layer. This provides the effect of having heat resistance that allows the film to be used in boiling sterilization, or heat resistance that allows the film to be used not only in boiling sterilization but also in retort sterilization, which involves pressurization and heating at over 100°C.

[0029] The sealant layer constituting the heat-resistant film of the second embodiment can be similar to the sealant layer constituting the heat-resistant film of the first embodiment.

[0030] The stretched polyamide resin layer constituting the heat-resistant film of the second embodiment can be similar to the stretched polyamide resin layer constituting the heat-resistant film of the first embodiment.

[0031] 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 sealant 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, similar to the stretched polyamide resin layer constituting the heat-resistant film of the first embodiment. 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, the heat-resistant film of the present invention can have heat resistance that allows retort sterilization.

[0032] The polyethylene terephthalate resin layer constituting the heat-resistant film of the second embodiment is preferably a biaxially oriented polyethylene terephthalate resin film, and the thickness can be in the range of 9 μm to 16 μm, preferably 9 μm to 12 μm.

[0033] 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.

[0034] 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.

[0035] The heat-resistant film according to the second aspect of the present invention may contain a plant-derived polyethylene resin in the sealant layer. In this case, the sealant layer preferably 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.

[0036] As the plant-derived polyethylene resin, known plant-derived polyethylene resins can be used.

[0037] The thickness of the heat-resistant film in the second embodiment can be in the range of 50 μm to 170 μm, preferably 50 μm to 80 μm.

[0038] The heat-resistant film of the second aspect of the present invention has a laminated structure including a stretched polyamide resin layer and a polyethylene terephthalate resin layer laminated on the linear low-density polyethylene resin layer constituting the sealant layer on one side of the sealant layer having a biomass layer containing baked shell powder, and therefore has high adhesion between the sealant layer and the stretched polyamide resin layer and the polyethylene terephthalate resin layer, and is excellent in heat resistance because interlayer peeling is suppressed even under pressurized and heated conditions. 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.

[0039] (Third aspect) The third embodiment of the heat-resistant film of the present invention has a laminated structure in which a sealant layer, a stretched polyamide resin layer located on one side of the sealant layer, and a metal thin film layer and a polyethylene terephthalate resin layer are laminated in this order on the side of the stretched polyamide resin layer opposite to the side on which the sealant layer is located, the sealant layer has 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, and the stretched polyamide resin layer is located on the linear low-density polyethylene resin layer side of the sealant layer. This provides the effect of having heat resistance that allows the film to be used in boiling sterilization, or heat resistance that allows the film to be used not only in boiling sterilization but also in retort sterilization in which pressurized heating is performed at more than 100°C.

[0040] The sealant layer constituting the heat-resistant film of the third embodiment may be similar to the sealant layer constituting the heat-resistant film of the first embodiment.

[0041] The stretched polyamide resin layer constituting the heat-resistant film of the third embodiment can be similar to the stretched polyamide resin layer constituting the heat-resistant film of the first embodiment.

[0042] The stretched polyamide resin layer constituting the heat-resistant film of the third 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 sealant 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, similar to the stretched polyamide resin layer constituting the heat-resistant film of the first embodiment. 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, the heat-resistant film of the present invention can have heat resistance that allows retort sterilization.

[0043] The metal thin film layer constituting the heat-resistant film of the third 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.

[0044] The polyethylene terephthalate resin layer constituting the heat-resistant film of the third embodiment is preferably a biaxially oriented polyethylene terephthalate resin film, and the thickness can be in the range of 9 μm to 16 μm, preferably 9 μm to 12 μm.

[0045] The heat-resistant film of the third embodiment can be produced, for example, by laminating a metal foil to a stretched polyamide resin film or a polyethylene terephthalate resin film using an adhesive by a typical dry lamination method. The heat-resistant film of the third embodiment thus provided with a metal thin film layer has an oxygen permeability of, for example, 0.5 ml / m 2 ·day or less, and the water vapor permeability is 0.5g / m 2 The product has excellent barrier properties of less than 1.5 days.

[0046] The thickness of the heat-resistant film in the third embodiment can be in the range of 50 μm to 170 μm, preferably 50 μm to 80 μm.

[0047] The heat-resistant film of the third aspect of the present invention described above has a laminated structure including an oriented polyamide 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, the linear low-density polyethylene resin layer constituting the sealant layer. Therefore, adhesion between the sealant layer and the oriented polyamide resin layer, the metal thin film layer, and the polyethylene terephthalate resin layer is high, interlayer delamination is suppressed even under pressurized and heated conditions, and the heat resistance is excellent.

[0048] [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 third aspects of the present invention described above.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] The above-mentioned embodiments of the heat-resistant film and the packaging bag using the same are merely examples, and the present invention is not limited to these embodiments. EXAMPLES

[0053] The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

[0054] [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.

[0055] (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.

[0056] This biomass resin composition was melted and extruded through a T-die, and then brought into contact with a forming roll to be cooled and solidified, to produce a 50 μm-thick film for a sealant layer (sealant layer sample 1) having a single-layer structure.

[0057] In addition, the above biomass resin composition and linear low-density polyethylene resin were used to produce a two-layered (50 μm thick) sealant layer film (sealant layer 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.

[0058] 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.

[0059] (Preparation of heat-resistant film) A single-layered stretched polyamide resin film A (thickness: 15 μm) was dry laminated on one side of the single-layered sealant layer film (sealant layer sample 1) prepared as described above, to produce a heat-resistant film (film sample 1) having a stretched polyamide resin layer on one side of the sealant layer.

[0060] In addition, the above-mentioned stretched polyamide resin film A was laminated by dry lamination on the biomass layer surface of the two-layer film for sealant layer (sealant layer sample 2) prepared as described above, to prepare a heat-resistant film (film sample 2-1) having a stretched polyamide resin layer on one side of the sealant layer.

[0061] In addition, the above-mentioned stretched polyamide resin film A was laminated by dry lamination on the linear low-density polyethylene resin layer surface of the two-layer sealant layer film (sealant layer sample 2) prepared as described above, to prepare a heat-resistant film (film sample 2-2) having a stretched polyamide resin layer on one side of the sealant layer.

[0062] Furthermore, the above-mentioned stretched polyamide resin film A was laminated by dry lamination on one side of the three-layer sealant layer film (sealant layer sample 3) prepared as described above, to prepare a heat-resistant film (film sample 3) having a stretched polyamide resin layer on one side of the sealant layer.

[0063] (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.

[0064] (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.

[0065] [Table 1]

[0066] As shown in Table 1, it was confirmed that the bag sample 3 has excellent heat resistance that allows retort sterilization. Also, it was confirmed that the bag sample 2-2 has excellent heat resistance that allows boiling 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.

[0067] [Example 2] (Preparation of film for sealant layer) Similar to the three types of films for sealant layers in Example 1 (sealant layer samples 1 to 3), three types of films for sealant layers (sealant layer samples 4 to 6) were produced.

[0068] (Preparation of heat-resistant film) A stretched polyamide resin film B (thickness 27 μm) was laminated by dry lamination on one side of the film for sealant layer (sealant layer sample 4) with a single-layer structure prepared as described above to form a stretched polyamide resin layer. The stretched polyamide resin film B used here was a laminated film in which a stretched polyamide resin film (thickness 15 μm) was laminated on a base film made of a biaxially stretched polyethylene terephthalate resin film (thickness 12 μm), and the stretched polyamide resin film surface was laminated on the film for sealant layer.

[0069] Next, a biaxially oriented polyethylene terephthalate resin film (thickness 12 μm) was laminated by dry lamination on the base film surface of the stretched polyamide resin film B to produce a heat-resistant film (film sample 4) having a stretched polyamide resin layer and a polyethylene terephthalate resin layer on one side of the sealant layer. The thickness of the polyethylene terephthalate resin layer constituting this heat-resistant film (film sample 4) was the total thickness of the biaxially oriented polyethylene terephthalate resin film which was the base film of the stretched polyamide resin film B and the biaxially oriented polyethylene terephthalate resin film located in the outermost layer, and was 24 μm.

[0070] In addition, the above-mentioned stretched polyamide resin film B and biaxially stretched polyethylene terephthalate resin film were laminated by dry lamination on the biomass layer surface of the two-layered film for sealant layer (sealant layer sample 5) prepared as described above, thereby producing a heat-resistant film (film sample 5-1) having a stretched polyamide resin layer and a polyethylene terephthalate resin layer on one side of the sealant layer.

[0071] In addition, the above-mentioned stretched polyamide resin film B and biaxially stretched polyethylene terephthalate resin film were laminated by dry lamination on the linear low-density polyethylene resin layer surface of the two-layered film for sealant layer (sealant layer sample 5) prepared as described above, thereby producing a heat-resistant film (film sample 5-2) having a stretched polyamide resin layer and a polyethylene terephthalate resin layer on one side of the sealant layer.

[0072] Furthermore, the above-mentioned stretched polyamide resin film B and biaxially stretched polyethylene terephthalate resin film were laminated by dry lamination on one side of the three-layered film for sealant layer (sealant layer sample 6) prepared as above, thereby producing a heat-resistant film (film sample 6) having a stretched polyamide resin layer and a polyethylene terephthalate resin layer on one side of the sealant layer.

[0073] (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.

[0074] (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 1, and the results are shown in Table 2 below.

[0075] [Table 2]

[0076] As shown in Table 2, it was confirmed that the bag samples 5-2 and 6 had excellent heat resistance that allowed them to be sterilized by retort. 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.

[0077] [Example 3] (Preparation of film for sealant layer) Similar to the three types of films for sealant layers in Example 1 (sealant layer samples 1 to 3), three types of films for sealant layers (sealant layer samples 7 to 9) were produced.

[0078] (Preparation of heat-resistant film) The same stretched polyamide resin film A used in Example 1 was dry laminated on one side of the film for sealant layer (sealant layer sample 7) having a single layer structure prepared as described above to form a stretched polyamide resin layer. Next, an aluminum foil (thickness 7 μm) was dry laminated on the stretched polyamide resin film A side, and further, a biaxially stretched polyethylene terephthalate resin film (thickness 12 μm) was dry laminated on the aluminum foil side to prepare a heat-resistant film (film sample 7) having a stretched polyamide resin layer, a metal thin film layer (aluminum foil), and a polyethylene terephthalate resin layer laminated in this order on one side of the sealant layer.

[0079] In addition, the above-mentioned stretched polyamide resin film A, aluminum foil, and biaxially stretched polyethylene terephthalate resin film were laminated by dry lamination on the biomass layer surface of the two-layered film for sealant layer (sealant layer sample 8) prepared as described above. In this way, a heat-resistant film (film sample 8-1) was produced that had a stretched polyamide resin layer, a metal thin film layer (aluminum foil), and a polyethylene terephthalate resin layer on one side of the sealant layer.

[0080] In addition, the above-mentioned stretched polyamide resin film A, aluminum foil, and biaxially stretched polyethylene terephthalate resin film were laminated by dry lamination on the linear low-density polyethylene resin layer surface of the two-layered film for sealant layer (sealant layer sample 8) prepared as described above. In this way, a heat-resistant film (film sample 8-2) was prepared, which had a stretched polyamide resin layer, a metal thin film layer (aluminum foil), and a polyethylene terephthalate resin layer on one side of the sealant layer.

[0081] Furthermore, the above-mentioned stretched polyamide resin film A, aluminum foil, and biaxially stretched polyethylene terephthalate resin film were laminated by dry lamination on one side of the three-layered film for sealant layer (sealant layer sample 9) prepared as above, thereby producing a heat-resistant film (film sample 9) having a stretched polyamide resin layer, a metal thin film layer (aluminum foil), and a polyethylene terephthalate resin layer on one side of the sealant layer.

[0082] (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.

[0083] (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 1, and the results are shown in Table 3 below.

[0084] [Table 3]

[0085] As shown in Table 3, it was confirmed that the bag sample 9 had excellent heat resistance that allowed for retort sterilization. Also, it was confirmed that the bag sample 8-2 had excellent heat resistance that allowed for boiling sterilization. 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.

[0086] [Example 4] (Preparation of film for sealant layer) Similar to the three types of films for sealant layers in Example 1 (sealant layer samples 1 to 3), three types of films for sealant layers (sealant layer samples 10 to 12) were produced.

[0087] (Preparation of heat-resistant film) The same stretched polyamide resin film B used in Example 2 was dry laminated on one side of the single-layered film for sealant layer (sealant layer sample 10) prepared as described above to form a stretched polyamide resin layer. The stretched polyamide resin film B used here was a laminated film in which a stretched polyamide resin film (thickness 15 μm) was 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 the film for the sealant layer.

[0088] Next, an aluminum foil (thickness 7 μm) was dry laminated on the base film surface of the stretched polyamide resin layer, and further, a biaxially stretched polyethylene terephthalate resin film (thickness 12 μm) was dry laminated on the aluminum foil surface, thereby producing a heat-resistant film (film sample 10) having a stretched polyamide resin layer, a polyethylene terephthalate resin layer, a metal thin film layer (aluminum foil), and a polyethylene terephthalate resin layer laminated in this order on one side of the sealant layer.

[0089] In addition, the above-mentioned stretched polyamide resin film B, aluminum foil, and biaxially stretched polyethylene terephthalate resin film were laminated by dry lamination on the biomass layer surface of the two-layered film for sealant layer (sealant layer sample 11) prepared as described above. In this way, a heat-resistant film (film sample 11-1) was produced that had a stretched polyamide resin layer, a polyethylene terephthalate resin layer, a metal thin film layer (aluminum foil), and a polyethylene terephthalate resin layer on one side of the sealant layer.

[0090] In addition, the above-mentioned stretched polyamide resin film B, aluminum foil, and biaxially stretched polyethylene terephthalate resin film were laminated by dry lamination on the linear low-density polyethylene resin layer surface of the two-layered film for sealant layer (sealant layer sample 11) prepared as described above. In this way, a heat-resistant film (film sample 11-2) was prepared, which had a stretched polyamide resin layer, a polyethylene terephthalate resin layer, a metal thin film layer (aluminum foil), and a polyethylene terephthalate resin layer on one side of the sealant layer.

[0091] Furthermore, the above-mentioned stretched polyamide resin film B, aluminum foil, and biaxially stretched polyethylene terephthalate resin film were laminated by dry lamination on one side of the three-layered film for sealant layer (sealant layer sample 12) prepared as above, thereby producing a heat-resistant film (film sample 12) having a stretched polyamide resin layer, a polyethylene terephthalate resin layer, a metal thin film layer (aluminum foil), and a polyethylene terephthalate resin layer on one side of the sealant layer.

[0092] (Making packaging bags) Four types of three-sided bags (bag samples 10, 11-1, 11-2, 12) were produced in the same manner as in Example 1 using the four types of heat-resistant films (film samples 10, 11-1, 11-2, 12) produced as described above.

[0093] (evaluation) The four types of packaging bags (bag samples 10, 11-1, 11-2, and 12) 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 1, and the results are shown in Table 4 below.

[0094] [Table 4]

[0095] As shown in Table 4, it was confirmed that the bag samples 11-2 and 12 had excellent heat resistance that allowed them to be sterilized by retort. In contrast, the bag samples 10 and 11-1 showed a decrease in laminate strength after boiling sterilization, and were confirmed to have poor heat resistance. [Industrial Applicability]

[0096] The heat-resistant film and packaging bag of the present invention are biomass films and biomass bags that 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 laminate structure including a sealant layer and a stretched polyamide resin layer located on one surface of the sealant layer, The sealant layer has a biomass layer containing 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 burnt shell powder in the sealant layer is in the range of 5% by mass to 30% by mass, A heat-resistant film, characterized in that the stretched polyamide resin layer is located on a surface of the linear low-density polyethylene resin layer of the sealant layer.

2. 2. The heat-resistant film according to claim 1, further comprising a polyethylene terephthalate resin layer on the surface of the stretched polyamide resin layer opposite to the surface on which the sealant layer is located.

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. 2. The heat-resistant film according to claim 1, characterized in that a metal thin film layer and a polyethylene terephthalate resin layer are laminated in this order on the surface of the stretched polyamide resin layer opposite to the surface on which the sealant layer is located.

5. 5. The heat-resistant film according to claim 4, wherein a polyethylene terephthalate resin layer is interposed between the stretched polyamide resin layer and the metal thin film layer.

6. Oxygen permeability is 140ml / m ２ day or less, and the water vapor permeability is 50 g / m ２ The heat-resistant film according to any one of claims 1 to 5, wherein the heat-resistant film has a heat resistance of 0.05 -day or less.

7. A packaging bag comprising the heat-resistant film according to any one of claims 1 to 5.

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