Laminate and bag made of said laminate

Abstract

To provide a laminate having strength and improved coloring resistance.SOLUTION: A laminate 30 at least has a first base material 41, a second base material 51 and a sealant layer 61 in the stated order. The second base material 51 contains 51 mass% or more of polyethylene terephthalate or 51 mass% or more of polybutylene terephthalate. If the second base material 51 contains 51 mass% or more of polyethylene terephthalate, the first base material 41 contains 51 mass% or more of polybutylene terephthalate. Preferably, the laminate 30 has a piercing strength of 13N or more. Preferably, the base material containing 51 mass% or more of polybutylene phthalate, out of the first base material 41 or second base material 51, has a multilayered structure made up of 10 or more layers, or has a single layered structure with an IV value of 1.10-1.35dl / g.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a laminate and a bag constructed from the laminate. [Background technology]

[0002] Conventionally, many bags made of plastic laminates have been available on the market, filled and sealed with cooked or semi-cooked liquid, viscous material, or a mixture of liquid and solid. In the bag, the non-sealed portion where the laminates are not joined constitutes the storage portion where the contents are stored. The sealed portion where the laminates are joined seals the storage portion. The contents are, for example, cooked foods such as curry, stew, or soup. The contents are heated in a hot water bath or the like while stored in the bag.

[0003] The laminate that constitutes the bag contains a plastic film as a substrate. For example, Patent Document 1 proposes using polyethylene terephthalate, polypropylene, nylon, or the like as the material for the substrate of the laminate. The substrate contributes to improving the strength of the laminate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-94767 Summary of the Invention [Problem to be solved by the invention]

[0005] Nylon is known as a material with high strength, but when nylon is used as the base material, it is likely to be discolored by the contents, which may impair the appearance of the bag.

[0006] An object of the present invention is to provide a laminate that can effectively solve these problems. [Means for solving the problem]

[0007] The present invention is a laminate comprising at least a first substrate, a second substrate, and a sealant layer in this order, wherein the second substrate contains 51% by mass or more of polyethylene terephthalate or 51% by mass or more of polybutylene terephthalate, and when the second substrate contains 51% by mass or more of polyethylene terephthalate, the first substrate contains 51% by mass or more of polybutylene terephthalate.

[0008] In the laminate according to the present invention, the piercing strength of the laminate may be 13 N or more.

[0009] In the laminate according to the present invention, the substrate containing 51% by mass or more of polybutylene terephthalate out of the first substrate and the second substrate may have a multilayer structure including 10 or more layers.

[0010] In the laminate according to the present invention, the substrate containing 51% by mass or more of polybutylene terephthalate out of the first substrate and the second substrate may have a single-layer structure having an IV value of 1.10 dl / g or more and 1.35 dl / g or less.

[0011] In the laminate according to the present invention, the first substrate may contain 51% by mass or more of polybutylene terephthalate, and the second substrate may contain 51% by mass or more of polyethylene terephthalate.

[0012] In the laminate according to the present invention, the first substrate may contain 51% by mass or more of polyethylene terephthalate, and the second substrate may contain 51% by mass or more of polybutylene terephthalate.

[0013] In the laminate according to the present invention, the sealant layer may comprise polypropylene.

[0014] In the laminate according to the present invention, the sealant layer may have a propylene content of 90% by mass or more.

[0015] In the laminate according to the present invention, the sealant layer may contain polyethylene having a melting point of 100°C or higher.

[0016] The laminate according to the present invention may further comprise a light-blocking printed layer located between the first substrate and the second substrate.

[0017] In the laminate according to the present invention, the light-shielding printed layer may have a thickness of 2 μm or more.

[0018] In the laminate according to the present invention, the light-shielding printed layer may contain a chromatic ink.

[0019] In the laminate according to the present invention, the light-shielding printed layer may contain achromatic ink.

[0020] The laminate according to the present invention may further comprise a picture printed layer located on the outer surface side of the laminate relative to the light-blocking printed layer.

[0021] In the laminate according to the present invention, the total light transmittance of the laminate may be 20% or less.

[0022] The laminate according to the present invention may further comprise a barrier layer between the first substrate and the second substrate, the barrier layer including at least a transparent vapor deposition layer provided on at least one of the first substrate or the second substrate.

[0023] In the laminate according to the present invention, the transparent vapor deposition layer may contain aluminum oxide, and a covalent bond between an aluminum atom and a carbon atom may be formed at the interface between the transparent vapor deposition layer and at least one of the first substrate and the second substrate on which the transparent vapor deposition layer is provided.

[0024] In the laminate according to the present invention, the barrier layer may further include a gas barrier coating film provided on the surface of the transparent vapor deposition layer.

[0025] The present invention is a bag comprising a laminate including an outer surface and an inner surface, and a seal portion joining the inner surfaces of the laminate, wherein the laminate comprises at least a first substrate, a second substrate, and a sealant layer, in this order from the outer surface side to the inner surface side, and the second substrate comprises 51% by mass or more of polyethylene terephthalate or 51% by mass or more of polybutylene terephthalate, and when the second substrate comprises 51% by mass or more of polyethylene terephthalate, the first substrate comprises 51% by mass or more of polybutylene terephthalate.

[0026] In the bag according to the present invention, the laminate may further include a light-blocking printed layer located between the first substrate and the second substrate. [Effects of the Invention]

[0027] According to the present invention, it is possible to provide a laminate having puncture resistance and staining resistance. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a front view showing a bag according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view showing an example of a layer structure of a laminate that constitutes a bag. [Figure 3] 10 is a cross-sectional view showing another example of the layer structure of the laminate constituting the bag. FIG. [Figure 4] FIG. 2 is a cross-sectional view showing an example of the layer structure of a first film of the laminate. [Figure 5] FIG. 10 is a diagram showing an example of a method for measuring puncture strength. [Figure 6] FIG. 1 is a diagram showing the layer configurations and evaluation results of Examples 1 to 4 and Comparative Examples 1 and 2. [Figure 7] 10 is a cross-sectional view showing another example of the layer structure of the laminate constituting the bag. FIG. [Figure 8] 10 is a cross-sectional view showing another example of the layer structure of the laminate constituting the bag. FIG. [Figure 9] 10 is a cross-sectional view showing another example of the layer structure of the laminate constituting the bag. FIG. [Figure 10] 10 is a cross-sectional view showing another example of the layer structure of the laminate constituting the bag. FIG. [Figure 11] FIG. 1 is a diagram showing the layer configurations and evaluation results of Examples 5 to 8 and Comparative Examples 3 and 4. DETAILED DESCRIPTION OF THE INVENTION

[0029] (First embodiment) An embodiment of the present invention will be described with reference to Figures 1 to 4. In the drawings accompanying this specification, the scale and aspect ratios have been appropriately changed and exaggerated from those of the actual objects for the sake of ease of illustration and understanding.

[0030] Furthermore, terms used in this specification that specify shapes, geometric conditions, and their degrees, such as "parallel," "orthogonal," and "identical," as well as values ​​of lengths and angles, are not to be construed as being bound by strict meanings, but rather as including a range within which similar functions can be expected.

[0031] First, the problem that this embodiment aims to solve will be described. The laminate that constitutes the bag may be required to have high light-blocking properties in order to preserve the contents while preventing deterioration of the contents. To solve these problems, for example, the above-mentioned Patent Document 1 proposes providing a light-blocking printed layer with light-blocking properties on a substrate containing a resin such as polyethylene terephthalate.

[0032] In Patent Document 1, the light-blocking printed layer is obtained by printing an ink containing a pigment and a binder to a sufficient thickness on a substrate. However, ink components such as pigments, binders, and residual solvents can produce odors that are unpleasant to humans (hereinafter also referred to as "off-odors"), which can permeate the sealant layer and adhere to the contents. Such off-odors are particularly problematic when the contents are food.

[0033] An object of the present embodiment is to provide a laminate that can effectively solve such problems.

[0034] Next, a description will be given of bag 10 according to this embodiment. Fig. 1 is a front view showing bag 10 according to this embodiment. Bag 10 has a storage section 17 that stores contents. Note that Fig. 1 shows bag 10 in a state before it is filled with contents (a state in which no contents are filled). Bag 10 according to this embodiment is configured so that it can be subjected to a retort process. The configuration of bag 10 will be described below.

[0035] bag In this embodiment, bag 10 is a gusset-type bag configured to be self-standing. Bag 10 includes an upper portion 11, a lower portion 12, and a side portion 13, and has a generally rectangular outline in a front view. Note that names such as "upper portion," "lower portion," and "side portion," as well as terms such as "above" and "below," merely describe the relative positions and directions of bag 10 and its components, based on a state in which bag 10 is self-standing with the gusset portion facing downwards. The position of bag 10 during transportation or use is not limited by the names and terms used in this specification.

[0036] 1, the bag 10 includes a surface film 14 that forms the surface, a back film 15 that forms the back, and a lower film 16 that forms the lower part 12. The lower film 16 is disposed between the surface film 14 and the back film 15 in a state where it is folded back at a folding portion 16f.

[0037] The terms "surface film," "back film," and "lower film" mentioned above merely distinguish each film according to its positional relationship, and the terms do not limit the method of providing the films when manufacturing bag 10. For example, bag 10 may be manufactured using one film in which surface film 14, back film 15, and lower film 16 are connected together, or may be manufactured using two films: one film in which surface film 14 and lower film 16 are connected together and one back film 15, or may be manufactured using three films: one surface film 14, one back film 15, and one lower film 16.

[0038] The inner surfaces of the front film 14, back film 15, and bottom film 16 are joined together by sealed portions. In a plan view of the bag 10 such as Figure 1, the sealed portions are hatched.

[0039] As shown in Figure 1, the seal portion has an outer edge seal portion that extends along the outer edge of bag 10. The outer edge seal portion includes a bottom seal portion 12a that extends to bottom 12, and a pair of side seal portions 13a that extend along a pair of side portions 13. Before contents are filled into bag 10, as shown in Figure 1, top 11 of bag 10 forms an opening 11b. After contents are placed in bag 10, the inner surfaces of front film 14 and back film 15 are joined at top 11 to form the top seal portion and seal bag 10.

[0040] The side seal portion 13a and the upper seal portion described below are seal portions formed by joining the inner surface of the front film 14 and the inner surface of the back film 15. On the other hand, the lower seal portion 12a includes a seal portion formed by joining the inner surface of the front film 14 and the inner surface of the bottom film 16, and a seal portion formed by joining the inner surface of the back film 15 and the inner surface of the bottom film 16.

[0041] There are no particular limitations on the method for forming the seal portion, as long as it is possible to join opposing films together and seal bag 10. For example, the seal portion may be formed by melting the inner surfaces of the films by heating or the like, welding the inner surfaces together, i.e., by heat sealing. Alternatively, the seal portion may be formed by bonding the inner surfaces of opposing films together using an adhesive or the like.

[0042] Easy-to-open means The front film 14 and the back film 15 may be provided with easy-open means 25 for tearing the front film 14 and the back film 15 to open the bag 10. For example, as shown in Fig. 1, the easy-open means 25 may include a notch 26 formed in the side seal portion 13a of the bag 10, which serves as a tearing starting point. Alternatively, the easy-open means 25 may be a half-cut line formed by laser processing or a cutter in a portion that serves as a path for tearing the bag 10.

[0043] Furthermore, although not shown, the easy-open means 25 may include a group of cuts or scars formed in the area where the seal portion is formed of the front film 14 and the back film 15. The group of scars may include, for example, a plurality of through holes formed so as to penetrate the front film 14 and / or the back film 15. Alternatively, the group of scars may include a plurality of holes formed on the outer surface of the front film 14 and / or the back film 15 so as not to penetrate the front film 14 and / or the back film 15.

[0044] Layer structure of the surface film and back film Next, the layer structure of the front surface film 14 and the back surface film 15 will be described. Fig. 2 is a cross-sectional view showing an example of a laminate 30 constituting the front surface film 14 and the back surface film 15. Fig. 3 is a cross-sectional view showing another example of a laminate 30 constituting the front surface film 14 and the back surface film 15.

[0045] 2, the laminate 30 includes at least a first film 40, a second film 50, and a third film 60, in this order. The first film 40 is located on the outer surface 30y side, and the third film 60 is located on the inner surface 30x side opposite the outer surface 30y. The inner surface 30x is the surface located on the storage section 17 side.

[0046] As shown in FIG. 2, the first film 40 includes at least a first substrate 41 and a light-shielding printed layer 42 provided on the surface of the first substrate 41 facing the second film 50. As shown in FIG. 3, the first film 40 may further include a picture printed layer 43 located between the first substrate 41 and the light-shielding printed layer 42. The second film 50 includes at least a second substrate 51. The third film 60 includes at least a sealant layer 61. The first film 40 and the second film 50 are bonded together by a first adhesive layer 45, and the second film 50 and the third film 60 are bonded together by a second adhesive layer 55. Therefore, the laminate 30 according to this embodiment includes, in order from the outer surface side to the inner surface side, First substrate / light-shielding printing layer / first adhesive layer / second substrate / second adhesive layer / sealant layer, or First substrate / pattern printed layer / light-shielding printed layer / first adhesive layer / second substrate / second adhesive layer / sealant layer It can be said that the layer has the following characteristics. Note that " / " indicates the boundary between layers.

[0047] The first film 40, the first adhesive layer 45, the second film 50, the second adhesive layer 55, and the third film 60 will be described in detail below.

[0048] (Film 1) 3, the first film 40 includes a first substrate 41 constituting the outer surface 30y of the laminate 30, a picture printed layer 43 provided on the inner surface 30x side of the first substrate 41, and a light-shielding printed layer 42 provided on the inner surface 30x side of the picture printed layer 43. First, the light-shielding printed layer 42 and the picture printed layer 43 will be described.

[0049] [Light-shielding printing layer] The light-shielding printed layer 42 is a layer configured to provide the laminate 30 with light-shielding properties. The light-shielding printed layer 42 contains ink containing a pigment and a binder. The thickness of the light-shielding printed layer 42 is, for example, 2 μm or more, preferably 3 μm or more, and more preferably 4 μm or more. The thickness of the light-shielding printed layer 42 is preferably 10 μm or less, and more preferably 6 μm or less. The total light transmittance of the laminate 30 including the light-shielding printed layer 42 is at least 20% or less, preferably 15% or less, and even more preferably 10% or less. When the total light transmittance is 20% or less, visible light and ultraviolet light consisting of external light in the wavelength range of 300 nm to 800 nm that enters the bag 10 under normal usage conditions can be effectively blocked, and deterioration of the contents stored in the bag 10 due to external light can be effectively suppressed.

[0050] The total light transmittance refers to the ratio of the total amount of transmitted light that passes through the laminate 30 to the total amount of light that enters a test piece made of the laminate 30 including the light-shielding printed layer 42. Since test pieces usually have light diffusibility, the total light transmittance is the sum of the parallel light transmittance and the diffuse transmittance. The total light transmittance is measured in accordance with the optical property test method JIS-K7361-1, which uses an integrating sphere as specified by JIS.

[0051] The light-shielding printing layer 42 includes an achromatic layer containing, for example, an achromatic ink. An achromatic color is a color that is described only by lightness, one of the three dimensions of color: hue, lightness, and saturation. Examples of achromatic colors include white, gray, and black. The thickness of the achromatic layer is, for example, 1 μm or more and 3 μm or less. The achromatic layer is preferably a single-color layer that extends across the entire surface of the first substrate 41 in the same plane. In the following description, a printing layer having an area where the area ratio of halftone dots is 100% is also referred to as a solid layer. For example, a printing layer having an area where the area ratio of white halftone dots is 100% is referred to as a white solid layer. Similarly, a printing layer having an area where the area ratio of black halftone dots is 100% is referred to as a black solid layer. The white solid layer is formed by solid printing a white ink containing a white pigment on the first substrate 41. The solid black layer is formed by solid printing a black ink containing a black pigment on the first substrate 41. The light-blocking printed layer 42 may include a plurality of laminated achromatic layers. The specific layer configuration of the light-blocking printed layer 42 will be described below.

[0052] The light-shielding printed layer 42 may be composed of, for example, a solid black layer. If a picture printed layer 43 is laminated on the outer surface 30y side of the light-shielding printed layer 42, when the bag 10 is viewed from the outer surface 30y side of the laminate, the light-shielding printed layer 42 will be observed as the background of the picture printed layer 43. For this reason, if the light-shielding printed layer 42 consists only of a solid black layer, it will be difficult to see the picture printed layer 43. Therefore, when the laminate 30 includes the picture printed layer 43, it is preferable that the light-shielding printed layer 42 further include, in addition to the solid black layer, an achromatic layer other than black, which is located closer to the outer surface 30y than the solid black layer, as described below.

[0053] The light-shielding printed layer 42 may include a solid white layer and an achromatic layer laminated in this order from the first substrate 41 side to the inner surface 30x side. The achromatic layer may be a solid white layer or a solid black layer. The achromatic layer may also be a solid gray layer formed by solid printing gray ink on the first substrate 41. The gray ink is obtained, for example, by mixing a white ink containing a white pigment and a black ink containing a black pigment. The gray ink preferably has a higher blend ratio of white ink than black ink. By using a solid gray layer as the achromatic layer laminated on the inner surface 30x side of the white solid layer, the color of the achromatic layer can be prevented from affecting the color of the picture printed layer 43, compared to when a solid black layer is laminated on the inner surface 30x side of the white solid layer. The number of achromatic layers is not limited to two. For example, the light-shielding printed layer 42 may include three or four or more stacked achromatic layers. For example, the light-shielding printed layer 42 may include a solid white layer, a solid white layer, and a solid gray layer stacked in this order from the first substrate 41 side to the inner surface 30x side.

[0054] The light-shielding printed layer 42 may also be made of a solid white layer. Even if the light-shielding printed layer 42 does not include the above-mentioned solid black layer or solid gray layer, the light-shielding printed layer 42 can have sufficient light-shielding properties by increasing the thickness of the solid white layer.

[0055] The light-blocking printing layer 42 may also have a chromatic color layer containing chromatic ink. A chromatic color refers to a color or color range that includes all three dimensions of color: hue, brightness, and saturation. In other words, a chromatic color is a color other than an achromatic color. The thickness of the chromatic color layer is, for example, 0.3 μm or more and 2 μm or less. The chromatic color layer is preferably a layer of a single color that extends across the entire surface of the first substrate 41 in the same plane. The light-blocking printing layer 42 may include multiple stacked chromatic color layers.

[0056] The light-shielding printed layer 42 may include both an achromatic layer and a chromatic layer. For example, the light-shielding printed layer 42 has one or more achromatic layers and one or more chromatic layers located closer to the inner surface 30x than the achromatic layers. The light-shielding printed layer 42 may also have one or more chromatic layers and one or more achromatic layers located closer to the inner surface 30x than the chromatic layers. For example, the light-shielding printed layer 42 may include a solid white layer and a chromatic layer stacked in this order from the first substrate 41 side to the inner surface 30x side.

[0057] [Picture printing layer] The picture printed layer 43 is a layer provided by printing to display product information and to impart an aesthetic appeal to the bag 10. The picture printed layer 43 expresses letters, numbers, symbols, figures, pictures, etc. In the picture printed layer 43, multiple color layers extend in the same plane. Ink for gravure printing or ink for flexographic printing can be used as a material for forming the picture printed layer 43. A specific example of gravure printing ink is Finart, manufactured by DIC Graphics Corporation.

[0058] [First base material] The first base material 41 contains polybutylene terephthalate (hereinafter also referred to as PBT) as a main component. For example, the first base material 41 contains 51 mass % or more of PBT. The advantages of the first base material 41 containing PBT will be described below.

[0059] PBT has excellent dimensional stability and therefore excellent printability, so similar to the case of polyethylene terephthalate (hereinafter also referred to as PET), a light-shielding printed layer 42 can be provided on a first substrate 41 containing PBT.

[0060] Furthermore, PBT has excellent heat resistance. This makes it possible to prevent deformation of first substrate 41 and reduction in strength of first substrate 41 when bag 10 is subjected to a sterilization treatment such as boiling or retort treatment. Retort treatment is a treatment in which bag 10 is filled with contents, sealed, and then heated under pressure. The temperature for retort treatment is, for example, 120°C or higher. Boiling treatment is a treatment in which bag 10 is filled with contents, sealed, and then heated in a water bath under atmospheric pressure. The temperature for boiling treatment is, for example, 90°C or higher and 100°C or lower.

[0061] Furthermore, PBT has high strength, so that bag 10 can be made puncture-resistant in the same way as when laminate 30 constituting bag 10 contains nylon.

[0062] Furthermore, PBT has the property of being less resistant to moisture absorption than nylon, which makes it possible to prevent the first base material 41 from absorbing moisture and thereby reducing the laminate strength of the laminate 30.

[0063] The configuration of the first base material 41 containing PBT will be described in detail below. In the present embodiment, the configuration of the first base material 41 containing PBT may be either the first configuration or the second configuration described below.

[0064] [First configuration of substrate] The PBT content in the first base material 41 according to the first configuration is preferably 51% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, particularly preferably 75% by mass or more, and most preferably 80% by mass or more. By making the PBT content 51% by mass or more, the first film 40 can have excellent impact strength and pinhole resistance.

[0065] The PBT used as the main constituent preferably contains 90 mol % or more, more preferably 95 mol % or more, even more preferably 98 mol % or more, and most preferably 100 mol % of terephthalic acid as a dicarboxylic acid component, and preferably contains 90 mol % or more, more preferably 95 mol % or more, even more preferably 97 mol % or more of 1,4-butanediol as a glycol component, and most preferably contains no by-products other than those formed by ether bonds of 1,4-butanediol during polymerization.

[0066] The first base material 41 may contain a polyester resin other than PBT, which makes it possible to adjust the film formability and mechanical properties of the first base material 41 when the film-like first base material 41 is biaxially stretched, for example. Examples of polyester resins other than PBT include polyester resins such as PET, polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), and polypropylene terephthalate (PPT), as well as PBT resins copolymerized with dicarboxylic acids such as isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, cyclohexanedicarboxylic acid, adipic acid, azelaic acid, and sebacic acid, and PBT resins copolymerized with diol components such as ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, cyclohexanediol, polyethylene glycol, polytetramethylene glycol, and polycarbonate diol.

[0067] The amount of the polyester resin other than PBT added is preferably 49% by mass or less, more preferably 40% by mass or less. If the amount of the polyester resin other than PBT added exceeds 49% by mass, the mechanical properties of PBT may be impaired, and impact strength, pinhole resistance, and draw formability may become insufficient.

[0068] The first substrate 41 may contain, as an additive, a polyester-based or polyamide-based elastomer obtained by copolymerizing at least one of a flexible polyether component, a polycarbonate component, and a polyester component. This can improve pinhole resistance when bent. The amount of additive added is, for example, 20% by mass. If the amount of additive added exceeds 20% by mass, the effect of the additive may become saturated, or the transparency of the first substrate 41 may decrease.

[0069] An example of a method for producing the film-shaped first substrate 41 according to the first configuration will be described. Here, a method for producing the film-shaped first substrate 41 by a casting method will be described. More specifically, a method for casting resins of the same composition in multiple layers will be described.

[0070] Because PBT has a fast crystallization rate, crystallization progresses even during casting. If PBT is cast as a single layer without being multilayered, there is no barrier to suppress crystal growth, so the crystals grow to a large size, increasing the yield stress of the resulting unstretched raw material. This makes the unstretched raw material more susceptible to breakage when biaxially stretched. Furthermore, the yield stress of the resulting biaxially stretched film is likely to be high, resulting in insufficient formability of the biaxially stretched film. In contrast, if the same resin is used in multiple layers during casting, the stretching stress of the unstretched sheet can be reduced, enabling stable biaxial stretching and lowering the yield stress of the resulting biaxially stretched film, resulting in a flexible film with high breaking strength.

[0071] FIG. 4 is a cross-sectional view showing an example of the layer structure of the first film. When the first substrate 41 is produced by casting a multilayered resin, as shown in FIG. 4, the first substrate 41 of the first film 40 is composed of a multilayer structure including multiple layers 41a. Each of the multiple layers 41a contains PBT as a main component. For example, each of the multiple layers 41a preferably contains 51% by mass or more of PBT, and more preferably 60% by mass or more of PBT. In addition, among the multiple layers 41a, the (n+1)th layer 41a is laminated directly on the nth layer 41a. In other words, no adhesive or bonding layer is interposed between the multiple layers 41a.

[0072] The reason why the properties of PBT film improve when multilayered is speculated to be as follows: When resins are laminated, even if the resin composition is the same, there is an interface between the layers, and this interface accelerates crystallization. On the other hand, the growth of large crystals that exceed the thickness of the layers is suppressed. This is thought to result in a smaller crystal (spherulite) size.

[0073] As a specific method for reducing the size of spherulites by multi-layering, a general multi-layering device (such as a multi-layer feed block, static mixer, or multi-layer multi-manifold) can be used. For example, a method can be used in which thermoplastic resins discharged from different flow paths using two or more extruders are laminated into multiple layers using a feed block, static mixer, or multi-manifold die. Note that when resins of the same composition are multi-layered, it is also possible to use only one extruder and introduce the above-mentioned multi-layering device into the melt line from the extruder to the die.

[0074] The first substrate 41 is composed of a multilayer structure portion including at least 10 layers 41a, preferably 60 layers or more, more preferably 250 layers or more, and even more preferably 1000 layers or more. Increasing the number of layers reduces the size of spherulites in the PBT in the unstretched raw roll state, allowing for stable biaxial stretching. It also reduces the yield stress of the PBT in the biaxially stretched film state. Preferably, the diameter of the spherulites in the PBT in the unstretched raw roll is 500 nm or less.

[0075] When an unstretched raw PBT is biaxially stretched to produce a biaxially stretched film, the stretching temperature in the machine direction (hereinafter referred to as MD) (hereinafter also referred to as MD stretching temperature) is preferably 40°C or higher, more preferably 45°C or higher. By setting the MD stretching temperature to 40°C or higher, it is possible to prevent the film from breaking. Furthermore, the MD stretching temperature is preferably 100°C or lower, more preferably 95°C or lower. By setting the MD stretching temperature to 100°C or lower, it is possible to prevent the biaxially stretched film from not being oriented.

[0076] The stretching ratio in MD (hereinafter also referred to as MD stretching ratio) is preferably 2.5 times or more. This allows the biaxially stretched film to be oriented, thereby achieving good mechanical properties and a uniform thickness. The MD stretching ratio is, for example, 5 times or less.

[0077] The stretching temperature in the transverse stretching direction (hereinafter also referred to as TD) (hereinafter also referred to as TD stretching temperature) is preferably 40°C or higher. By setting the TD stretching temperature to 40°C or higher, it is possible to prevent the film from breaking. Furthermore, the TD stretching temperature is preferably 100°C or lower. By setting the TD stretching temperature to 100°C or lower, it is possible to prevent the phenomenon in which the biaxially stretched film does not become oriented.

[0078] The stretching ratio in TD (hereinafter also referred to as TD stretching ratio) is preferably 2.5 times or more. This allows the biaxially stretched film to be oriented, thereby achieving good mechanical properties and a uniform thickness. The stretching ratio in MD is, for example, 5 times or less.

[0079] The TD relaxation ratio is preferably 0.5% or more, which can prevent the biaxially stretched PBT film from breaking during heat setting. The TD relaxation ratio is preferably 10% or less, which can prevent the biaxially stretched PBT film from becoming slack and causing thickness unevenness.

[0080] 4, the thickness of the layer 41a of the first base material 41 is preferably 3 nm or more, and more preferably 10 nm or more. The thickness of the layer 41a is preferably 200 nm or less, and more preferably 100 nm or less. The thickness of the first substrate 41 is preferably 9 μm or more, and more preferably 12 μm or more. The thickness of the first substrate 41 is preferably 25 μm or less, and more preferably 20 μm or less. By making the thickness of the first substrate 41 9 μm or more, the first substrate 41 has sufficient strength. By making the thickness of the first substrate 41 25 μm or less, the first substrate 41 exhibits excellent formability. Therefore, the step of manufacturing the bag 10 by processing the laminate 30 including the first substrate 41 can be carried out efficiently.

[0081] [Second configuration of substrate] The first substrate 41 according to the second configuration is a monolayer film containing a polyester whose main repeating unit is butylene terephthalate. For example, the first substrate 41 includes a homo- or copolymer-type polyester obtained by condensing 1,4-butanediol or its ester-forming derivative as the glycol component and terephthalic acid or its ester-forming derivative as the dibasic acid component. The PBT content in the first substrate 41 according to the second configuration is preferably 51% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and most preferably 90% by mass or more. The first substrate 41 according to the second configuration is preferably composed only of polybutylene terephthalate and additives.

[0082] To provide mechanical strength to the first substrate 41, PBTs having a melting point of 200°C or more and 250°C or less and an IV value of 1.10 dL / g or more and 1.35 dL / g or less are preferred. Furthermore, PBTs having a melting point of 215°C or more and 225°C or less and an IV value of 1.15 dL / g or more and 1.30 dL / g or less are particularly preferred. These IV values ​​may be satisfied by the entire material constituting the first substrate 41. The IV value can be calculated based on JIS K 7367-5:2000.

[0083] The first substrate 41 according to the second configuration may contain 30% by mass or less of a polyester resin other than PBT, such as PET. By including PET in addition to PBT in the first substrate 41, PBT crystallization can be suppressed, improving the stretchability of the PBT film. The PET blended with the PBT of the first substrate 41 can be a polyester whose main repeating unit is ethylene terephthalate. For example, a homotype primarily composed of ethylene glycol as the glycol component and terephthalic acid as the dibasic acid component is preferably used. To provide good mechanical strength, PETs with a melting point of 240°C to 265°C and an IV value of 0.55 dl / g to 0.90 dl / g are preferred. Furthermore, PETs with a melting point of 245°C to 260°C and an IV value of 0.60 dl / g to 0.80 dl / g are particularly preferred. By keeping the PET content at 30% by mass or less, it is possible to prevent the rigidity of the unstretched raw material and the stretched film from becoming too high. This prevents the stretched film from becoming brittle, which would reduce the pressure resistance, impact strength, puncture strength, etc. of the stretched film. It also prevents poor stretching when stretching the unstretched raw material.

[0084] The first substrate 41 may contain additives such as lubricants, antiblocking agents, inorganic fillers, antioxidants, UV absorbers, antistatic agents, flame retardants, plasticizers, colorants, crystallization inhibitors, and crystallization accelerators, as needed. In order to avoid a decrease in viscosity due to hydrolysis during heat melting, the polyester resin pellets used as the raw material for the first substrate 41 are preferably pre-dried sufficiently before heat melting so that the moisture content is 0.05% by weight or less, and preferably 0.01% by weight or less.

[0085] An example of a method for producing the film-like first base material 41 according to the second configuration will be described.

[0086] To stably produce the film of the first substrate 41 having the above-described configuration, it is important to suppress crystal growth in the unstretched raw web. Specifically, when cooling an extruded PBT melt to form a film, the crystallization temperature range of the polymer must be cooled at a certain rate or higher; that is, the raw web cooling rate is an important factor. The raw web cooling rate is, for example, 200°C / sec or higher, preferably 250°C / sec or higher, and particularly preferably 350°C / sec or higher. Unstretched raw webs formed into films at high cooling rates maintain a low crystallinity, improving bubble stability during stretching. Furthermore, high-speed film formation is possible, thereby improving film productivity. If the cooling rate is less than 200°C / sec, the resulting unstretched raw web may have high crystallinity and poor stretchability. In extreme cases, the stretching bubbles may burst, preventing the stretching process from continuing.

[0087] The unstretched raw material containing PBT as a main component is preferably transported to the space where biaxial stretching is performed while maintaining the ambient temperature at 25° C. or less, preferably 20° C. or less. This allows the crystallinity of the unstretched raw material immediately after film formation to be maintained even if the residence time is long.

[0088] The biaxial stretching method for stretching an unstretched raw sheet to obtain a stretched film is not particularly limited. For example, by a tubular method or a tenter method, stretching may be performed simultaneously in the longitudinal direction and the transverse direction, or sequentially in the longitudinal direction and the transverse direction. Among these, the tubular method is particularly preferred because it can obtain a stretched film with a good balance of physical properties in the circumferential direction.

[0089] In the tubular method, the unstretched raw film introduced into the stretching space is passed between a pair of low-speed nip rolls and heated by a stretching heater while pressurized air is injected between them. After stretching is completed, air is blown onto the stretched film using a cooling shoulder air ring. Taking into consideration the stretching stability and the strength properties, transparency, and thickness uniformity of the stretched film, the stretching ratio is preferably 2.7 times or more and 4.5 times or less in both MD and TD. By setting the stretching ratio to 2.7 times or more, the tensile modulus and impact strength of the stretched film can be sufficiently ensured. Furthermore, by setting the stretching ratio to 4.5 times or less, excessive molecular chain distortion due to stretching can be suppressed, thereby suppressing the occurrence of breakage or punctures during stretching, thereby enabling the stable production of stretched films.

[0090] The stretching temperature is preferably 40°C or higher and 80°C or lower, and particularly preferably 45°C or higher and 65°C or lower. Because the unstretched raw film produced at the above-mentioned high cooling rate has low crystallinity, it can be stably stretched even at a relatively low stretching temperature. Furthermore, by setting the stretching temperature to 80°C or lower, the fluctuation of the stretching bubble can be suppressed, resulting in a stretched film with good thickness accuracy. Furthermore, by setting the stretching temperature to 40°C or higher, excessive stretch-oriented crystallization due to low-temperature stretching can be suppressed, preventing whitening of the film.

[0091] The first substrate 41 produced as described above is composed of a single layer containing, for example, a polyester whose main repeating unit is butylene terephthalate. According to the above-described production method, the unstretched raw material is formed at a high cooling rate, so that even if the unstretched raw material is composed of a single layer, it can maintain a low crystallinity, and therefore the unstretched raw material can be stably stretched.

[0092] (First adhesive layer) The first adhesive layer 45 includes a first adhesive for bonding the first film 40 and the second film 50. Examples of the first adhesive include an ether-based two-component reactive adhesive and an ester-based two-component reactive adhesive.

[0093] An example of an ether-based two-component reactive adhesive is polyether polyurethane. Polyether polyurethane is a cured product produced by reacting a polyether polyol as a base resin with an isocyanate compound as a curing agent. Examples of isocyanate compounds that can be used include aromatic isocyanate compounds such as tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), and xylylene diisocyanate (XDI), aliphatic isocyanate compounds such as hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI), and adducts or polymers of the above-mentioned various isocyanate compounds.

[0094] Examples of ester-based two-component reactive adhesives include polyester polyurethane and polyester. Polyester polyurethane is a cured product produced by reacting a polyester polyol as a base material with an isocyanate compound as a curing agent. Examples of the isocyanate compound are the same as those for the ether-based adhesives described above.

[0095] (2nd film) The second film 50 includes at least a second substrate 51. The second substrate 51 includes PET as a main component. For example, the second substrate 51 includes 51% by mass or more of PET. When the second substrate 51 includes PET, the second substrate 51 can have heat resistance. For example, compared to when the second substrate 51 includes nylon, the melting point of the second substrate 51 is higher and the moisture absorption of the second substrate 51 is lower. This can prevent holes from being formed in the second substrate 51 due to overheated water or the like when the bag 10 is heated. Furthermore, the heat resistance of PET is higher than that of PBT. Therefore, according to the present embodiment, the heat resistance of the laminate 30 can be improved even compared to when the second substrate 51 is made of PBT. This can prevent damage to the laminate 30 and a decrease in performance of the laminate 30 when the bag 10 is heated, for example.

[0096] The thickness of the second substrate 51 is preferably 9 μm or more, and more preferably 12 μm or more. The thickness of the second substrate 51 is preferably 25 μm or less, and more preferably 20 μm or less. By making the thickness of the second substrate 51 9 μm or more, the second substrate 51 has sufficient strength. By making the thickness of the second substrate 51 25 μm or less, the second substrate 51 exhibits excellent formability. Therefore, the step of processing the laminate 30 to manufacture the bag 10 can be carried out efficiently.

[0097] (Second adhesive layer) The second adhesive layer 55 includes a second adhesive for bonding the second film 50 and the third film 60 together. An example of the second adhesive is an ether-based two-component reactive adhesive. As with the first adhesive, an example of the ether-based two-component reactive adhesive is polyurethane. Polyurethane is a cured product produced by reacting a polyol as a base agent with an isocyanate compound as a curing agent. While polyether polyols and polyester polyols can be used as the polyol, polyester polyols are preferably used.

[0098] As described above, isocyanate compounds include aromatic isocyanate compounds and aliphatic isocyanate compounds. Of these, aromatic isocyanate compounds leach out components that make them unsuitable for food applications under high-temperature conditions such as heat sterilization. Meanwhile, as shown in FIGS. 2 and 3 , the second adhesive layer 55 is in contact with the third film 60. Therefore, if the second adhesive layer 55 contains an aromatic isocyanate compound, components leach out from the aromatic isocyanate compound may adhere to the contents of the bag 10 formed from the laminate 30.

[0099] In consideration of these issues, we propose using a cured product produced by the reaction of a polyol as the main agent with an aliphatic isocyanate compound as the curing agent as the second adhesive that constitutes second adhesive layer 55. This makes it possible to prevent components that cannot be used for food applications from being attached to the contents due to second adhesive layer 55.

[0100] (3rd film) The third film 60 includes at least a sealant layer 61 that forms the inner surface 30x of the laminate 30. The material that forms the sealant layer 61 can be one or more resins selected from polyethylene, such as low-density polyethylene and linear low-density polyethylene, and polypropylene. The sealant layer 61 may be a single layer or a multilayer. The sealant layer 61 is preferably made of an unstretched film.

[0101] The melting point of the material that constitutes sealant layer 61 is preferably 150°C or higher, and more preferably 160°C or higher. Increasing the melting point of sealant layer 61 makes it possible to perform retort processing of bag 10 at a high temperature, thereby shortening the time required for retort processing. Note that the melting point of the material that constitutes sealant layer 61 is lower than the melting point of the resin that constitutes first base material 41 and the melting point of the resin that constitutes second base material 51.

[0102] Preferably, the sealant layer 61 contains a propylene-ethylene block copolymer. For example, the third film 60 including the sealant layer 61 is an unstretched film whose main component is a propylene-ethylene block copolymer. By using a propylene-ethylene block copolymer, the impact resistance of the third film 60 can be increased, thereby preventing the bag 10 from breaking due to an impact when dropped. Furthermore, the puncture resistance of the laminate 30 can be increased.

[0103] The sealant layer 61 may further contain a thermoplastic elastomer. By using a thermoplastic elastomer, the impact resistance and puncture resistance of the third film 60 can be further improved.

[0104] The thermoplastic elastomer is, for example, a hydrogenated styrene-based thermoplastic elastomer. The hydrogenated styrene-based thermoplastic elastomer has a structure consisting of a polymer block A mainly composed of at least one vinyl aromatic compound and a polymer block B mainly composed of at least one hydrogenated conjugated diene compound. The thermoplastic elastomer may also be an ethylene-α-olefin elastomer. The ethylene-α-olefin elastomer is a low-crystalline or amorphous copolymer elastomer, and is a random copolymer of 50 to 90% by mass of ethylene as the main component and an α-olefin as a copolymerization monomer.

[0105] The content of the propylene-ethylene block copolymer in the sealant layer 61 is, for example, 80% by mass or more, and preferably 90% by mass or more.

[0106] Propylene-ethylene block copolymers can be produced by polymerizing the raw materials propylene and ethylene using a catalyst, such as a Ziegler-Natta catalyst or a metallocene catalyst.

[0107] The thickness of the sealant layer 61 is preferably 30 μm or more, and more preferably 40 μm or more. The thickness of the sealant layer 61 is preferably 100 μm or less, and more preferably 80 μm or less.

[0108] Layer structure of the bottom film Next, the layer structure of the lower film 16 will be described.

[0109] The layer configuration of the lower film 16 is arbitrary as long as it has an inner surface that can be bonded to the inner surfaces of the front film 14 and the back film 15. For example, the above-mentioned laminate 30 may be used as the lower film 16, similar to the front film 14 and the back film 15. Alternatively, a film whose inner surface is formed by a sealant layer and has a different configuration from the laminate 30 may be used as the lower film 16.

[0110] First film manufacturing method Next, an example of a method for manufacturing the first film 40 will be described.

[0111] First, a resin material containing PBT as a main component is prepared. Next, the resin material is extruded by a melt extrusion method such as a casting method or a tubular method to produce a film-like first substrate 41. Next, a picture printed layer 43 and a light-blocking printed layer 42 are formed on the first substrate 41. In this manner, a first film 40 including the first substrate 41, the light-blocking printed layer 42, and the picture printed layer 43 can be obtained.

[0112] Manufacturing method of laminate Next, an example of a method for manufacturing the laminate 30 will be described.

[0113] First, the above-described first film 40 and second film 50 are prepared. Next, the first film 40 and the second film 50 are laminated together via a first adhesive layer 45 by dry lamination. After that, the laminate including the first film 40 and the second film 50 and the third film 60 are laminated together via a second adhesive layer 55 by dry lamination. In this way, a laminate 30 including the first film 40, the second film 50, and the third film 60 can be obtained.

[0114] Alternatively, the laminate 30 may be produced by first laminating the second film 50 and the third film 60 via the second adhesive layer 55, and then laminating the first film 40 and a laminate including the second film 50 and the third film 60 via the first adhesive layer 45.

[0115] Bag manufacturing method The surface film 14 and back film 15 made of the laminate 30 described above are prepared. The folded bottom film 16 is inserted between the surface film 14 and back film 15. The inner surfaces of the films are then heat-sealed to form seals such as bottom seal 12a and side seal 13a. The heat-sealed films are then cut into an appropriate shape to obtain the bag 10 shown in FIG. 1 . The contents are then filled into the bag 10 through the opening 11b of the top 11. The contents are, for example, cooked foods such as curry, stew, and soup. In addition to food, items that can be heated in a hot water bath or the like can also be placed in the bag 10. The top 11 is then heat-sealed to form the top seal. In this manner, the bag 10 containing and sealed with the contents can be obtained.

[0116] The advantages of the bag 10 according to this embodiment will be described below.

[0117] In this embodiment, the laminate 30 constituting the front film 14 and the back film 15 of the bag 10 contains the first base material 41 containing PBT as a main component, thereby achieving the following effects. First, PBT has excellent printability, so that a light-shielding printed layer 42 and a picture printed layer 43 can be provided on a first base material 41 containing PBT, similar to the case of polyethylene terephthalate (hereinafter also referred to as PET). Furthermore, PBT has excellent heat resistance, which makes it possible to prevent first base material 41 from being deformed or losing its strength when bag 10 is subjected to a retort treatment, boiling treatment, or the like. Furthermore, PBT has high strength. Therefore, similar to when the laminate constituting bag 10 contains nylon, it is possible to increase the puncture strength of laminate 30 and bag 10. The puncture strength of laminate 30 is preferably 13 N or more, more preferably 15 N or more, and even more preferably 17 N or more. A method for measuring the puncture strength will be described in Example 1 below. Furthermore, PBT has the property of being less resistant to moisture absorption than nylon, so even if the first base material 41 containing PBT is disposed on the outer surface 30y of the laminate 30, it is possible to prevent the first base material 41 from absorbing moisture and thereby reducing the laminate strength of the laminate 30.

[0118] Furthermore, in this embodiment, the laminate 30 includes a light-blocking printed layer 42 located between the first substrate 41 and the second substrate 51. This prevents external light from passing through the laminate 30 and irradiating the contents, thereby preventing the contents from being deteriorated by external light.

[0119] Furthermore, in this embodiment, the laminate 30 includes the second base material 51 primarily composed of PET, which makes it possible to prevent unpleasant odors generated in the light-shielding printed layer 42 from penetrating through the second film 50 and the third film 60 and adhering to the contents, compared to when the second base material 51 is made of nylon. Also, the heat resistance of the laminate 30 can be improved, compared to when the second base material 51 is made of PBT. This makes it possible to prevent, for example, damage to the front film 14 and the back film 15 when the bag 10 is heated, which would otherwise cause a decrease in the performance of the front film 14 and the back film 15.

[0120] Furthermore, according to this embodiment, the sealant layer 61 of the laminate 30 that constitutes the front film 14 and the back film 15 of the bag 10 contains a propylene-ethylene block copolymer, which can improve the impact resistance and puncture resistance of the bag 10.

[0121] It should be noted that various modifications can be made to the above-described embodiment. Below, modifications will be described with reference to the drawings as necessary. In the following description and the drawings used in the following description, parts that can be configured similarly to the above-described embodiment will be designated by the same reference numerals as those used for the corresponding parts in the above-described embodiment, and duplicated explanations will be omitted. Furthermore, if it is clear that the effects obtained in the above-described embodiment can also be obtained in the modified embodiment, the explanations thereof may be omitted.

[0122] (Modification of Layer Structure) In the above-described present embodiment, an example has been shown in which the first substrate 41 contains 51% by mass or more of PBT and the second substrate 51 contains 51% by mass or more of PET, thereby improving the puncture resistance and heat resistance of the laminate 30. However, this is not limited thereto, and the first substrate 41 may contain 51% by mass or more of PET and the second substrate 51 may contain 51% by mass or more of PBT, thereby improving the puncture resistance and heat resistance of the laminate 30. As the PBT of the second substrate 51, the PBT according to the first configuration or the PBT according to the second configuration described above for the first substrate 41 can be used.

[0123] The second base material 51 containing 51% by mass or more of PBT and the first base material 41 containing 51% by mass or more of PET also contribute to improving the dimensional stability and printability of the laminate 30.

[0124] Furthermore, both the first base material 41 and the second base material 51 may contain 51% by mass or more of PBT. In this case, the PBT may be the PBT according to the first configuration or the PBT according to the second configuration described above for the first base material 41.

[0125] Examples of combinations of materials constituting the first substrate 41 and the second substrate 51 are summarized in Table 1. In Table 1, the notation "PBT" means that the resin constituting the film of the first substrate 41 or the second substrate 51 contains 51 mass % or more of PBT. In Table 1, the notation "PET" means that the resin constituting the film of the first substrate 41 or the second substrate 51 contains 51 mass % or more of PET. [Table 1]

[0126] Furthermore, in the above-described embodiment, an example has been shown in which the light-shielding printed layer 42 and the picture printed layer 43 are provided on the inner surface 30x side of the first substrate 41, but this is not limited to this. The arrangement of each layer is arbitrary as long as the light-shielding printed layer 42 is located between the first substrate 41 and the second substrate 51, and if the picture printed layer 43 is provided, the picture printed layer 43 is located closer to the outer surface 30y than the light-shielding printed layer 42. For example, the light-shielding printed layer 42 and the picture printed layer 43 may be provided on the outer surface 30y side of the second substrate 51. Alternatively, the light-shielding printed layer 42 may be provided on the outer surface 30y side of the second substrate 51, and the picture printed layer 43 may be provided on the inner surface 30x side of the first substrate 41. Examples of the arrangement of each layer are listed below. Arrangement example 1: First substrate / light-shielding printing layer / first adhesive layer / second substrate / second adhesive layer / sealant layer Arrangement example 2: First base material / pattern printed layer / light-blocking printed layer / first adhesive layer / second base material / second adhesive layer / sealant layer Arrangement example 3: First substrate / first adhesive layer / light-shielding printing layer / second substrate / second adhesive layer / sealant layer Arrangement example 4: First base material / first adhesive layer / pattern printed layer / light-blocking printed layer / second base material / second adhesive layer / sealant layer Arrangement example 5: First base material / pattern printed layer / first adhesive layer / light-blocking printed layer / second base material / second adhesive layer / sealant layer

[0127] (Variations of the bag) In the above-described embodiment, an example has been shown in which bag 10 is a gusseted bag, but there are no particular limitations on the specific configuration of bag 10. For example, bag 10 may be a so-called four-sided sealed bag formed by joining the inner surfaces of front film 14 and back film 15 made of laminate 30 at upper portion 11, lower portion 12, and side portion 13.

[0128] (Laminate according to the second embodiment) In the first embodiment described above, the laminate 30 is configured to include a light-shielding printed layer 42, but the scope of the present invention is not limited to this. FIG. 7 is a cross-sectional view showing an example of a laminate 30 according to a second embodiment. The laminate 30 shown in FIG. 7 differs only in that it does not include a light-shielding printed layer 42, and other configurations are substantially the same as the laminate 30 according to the first embodiment described above and shown in FIG. 2 or 3. In the laminate 30 according to the second embodiment, the same parts as those in the laminate 30 according to the first embodiment are given the same reference numerals, and detailed description thereof will be omitted. Furthermore, if it is clear that the effects obtained in the first embodiment can also be obtained in the second embodiment, the description thereof may be omitted.

[0129] 7, the laminate 30 includes at least a first film 40, a second film 50, and a third film 60, in this order. The first film 40 is located on the outer surface 30y side, and the third film 60 is located on the inner surface 30x side opposite the outer surface 30y. The inner surface 30x is the surface located on the storage section 17 side.

[0130] As shown in FIG. 7, the first film 40 includes at least a first substrate 41. The second film 50 includes at least a second substrate 51. The third film 60 includes at least a sealant layer 61. The first film 40 and the second film 50 are joined together by a first adhesive layer 45, and the second film 50 and the third film 60 are joined together by a second adhesive layer 55. Therefore, the laminate 30 according to the second embodiment includes the following layers in order from the outer surface side to the inner surface side: First substrate / first adhesive layer / second substrate / second adhesive layer / sealant layer; It can be said that the substrate 40 has the above-mentioned pattern printed layer 43. Note that " / " indicates the boundary between layers. Although not shown, the above-mentioned pattern printed layer 43 may be provided on the first substrate 41 or the second substrate 51 between the first substrate 41 and the second substrate 51.

[0131] In the present embodiment, as in the first embodiment described above, at least one of the first base material 41 and the second base material 51 contains 51 mass % or more of PBT, which can improve the puncture resistance and heat resistance of the laminate 30.

[0132] Also in this embodiment, as in the first embodiment, the second base material 51 contains 51% by mass or more of PBT or 51% by mass or more of PET. The effects of the second base material 51 containing PBT or PET will be described below. Here, the effects will be described based on a comparison with the case where the second base material 51 contains nylon.

[0133] Nylon is susceptible to penetration of the components of the contents. Therefore, if the second substrate 51 facing the sealant layer 61 contains nylon, it is conceivable that the second substrate 51 will be discolored by the contents. Such discoloration is likely to occur when the contents are subjected to high-temperature treatment such as retort treatment or boiling treatment. In contrast, PET and PBT are less susceptible to penetration of the components of the contents. Therefore, by constructing the second substrate 51 facing the sealant layer 61 from PBT or PET, it is possible to prevent the second substrate 51 from being discolored by the contents. This makes it possible to prevent damage to the appearance of the bag 10.

[0134] Furthermore, nylon has high moisture absorption properties. Therefore, when the second substrate 51 contains nylon, the second substrate 51 is likely to absorb moisture. Therefore, when the bag 10 is heated, the moisture contained in the second substrate 51 may cause foaming, which may impair the appearance of the bag 10. Such foaming is particularly likely to occur in the bottom seal portion 12a and the side seal portion 13a, where the front film 14 and the back film 15 are overlapped and joined. In contrast, the moisture absorption properties of PBT and PET are lower than that of nylon. Therefore, by constructing the second substrate 51 from PBT or PET, it is possible to prevent moisture from being absorbed into the second substrate 51. This prevents foaming in the bag 10 and thus prevents the appearance of the bag 10 from being impaired.

[0135] Furthermore, when second base material 51 contains nylon, caprolactam and other substances, which are raw materials for nylon and for which elution standards are set in Ministry of Health, Labour and Welfare Notification No. 370 "Apparatus, Containers and Packaging," may leach from the nylon and become mixed into the contents. In contrast, according to the present embodiment, second base material 51 is made of PBT or PET, thereby reducing the risk of caprolactam and other substances leaching out.

[0136] The effects of suppressing discoloration, foaming, and leaching of substances into the contents are achieved by constructing the second substrate 51 from PBT or PET, and can naturally also be achieved in the first embodiment described above.

[0137] The combination of materials constituting the first base material 41 and the second base material 51 in the second embodiment may be the same as the combinations shown in the first embodiment and the modifications described above. For example, the combinations may be the same as those shown in Table 1.

[0138] When it is possible to select whether the first substrate 41 contains PET or PBT, it is preferable from the viewpoint of heat-sealability that the first substrate 41 contains PET. PET has a relatively higher melting point than PBT. Therefore, by including PET in the first substrate 41, which is the substrate located closer to the outer surface 30y of the bag 10, the heat resistance of the first substrate 41 is further improved. As a result, when the sealed portion of the bag 10 is formed by heat-sealing, heat-sealing can be performed at a higher temperature.

[0139] Next, we will explain the sealant layer 61. As described above, the bag 10 formed from the laminate 30 is subjected to a sterilization treatment such as boiling or retort treatment at high temperatures. Therefore, the sealant layer 61 used must have heat resistance that can withstand these high-temperature treatments.

[0140] From the perspective of retort processing, a material primarily composed of propylene can be used as the material for the sealant layer 61. Here, a material "primarily composed of" propylene means a material with a propylene content of 90% by mass or more. Specific examples of materials primarily composed of propylene include the propylene-ethylene block copolymer described as the material for the sealant layer 61 in the first embodiment, as well as propylene-ethylene random copolymers, polypropylenes such as homopolypropylene, and mixtures of polypropylene and polyethylene. Here, "propylene-ethylene block copolymer" refers to a material having the structural formula shown in formula (I) below. Furthermore, "propylene-ethylene random copolymer" refers to a material having the structural formula shown in formula (II) below. Furthermore, "homopolypropylene" refers to a material having the structural formula shown in formula (III) below.

[0141] [ka]

[0142] [ka]

[0143] [ka]

[0144] When a mixture of polypropylene and polyethylene is used as the propylene-based material, the material may have an island-in-a-sea structure, where the polyethylene is discontinuously dispersed within a continuous polypropylene region.

[0145] Considering the boiling treatment, examples of the material constituting the sealant layer 61 include polyethylene, polypropylene, and a combination thereof. Examples of polyethylene include medium-density polyethylene, linear low-density polyethylene, and a combination thereof. For example, it is also possible to use the materials listed as materials constituting the sealant layer from the viewpoint of the retort treatment described above. The material constituting the sealant layer has a melting point of, for example, 100°C or higher, more preferably 105°C or higher, and even more preferably 110°C or higher. When polyethylene is used as the material constituting the sealant layer, a melting point of 100°C or higher is achieved, for example, when the density of polyethylene is 0.920 g / cm. 3 This can be achieved when the above conditions are satisfied. Specific examples of sealant films for forming a sealant layer having a melting point of 100°C or higher include TUX-HC manufactured by Mitsui Chemicals Tohcello, L6101 manufactured by Toyobo, and LS700C manufactured by Idemitsu Unitech. Specific examples of sealant films for forming a sealant layer having a melting point of 105°C or higher include NB-1 manufactured by Tamapoly. Specific examples of sealant films for forming a sealant layer having a melting point of 110°C or higher include LS760C manufactured by Idemitsu Unitech and TUX-HZ manufactured by Mitsui Chemicals Tohcello.

[0146] The sealant layer 61 may be a single layer or multiple layers, as in the first embodiment. The materials for the sealant layer 61 described above can also be applied to the sealant layer 61 of the laminate 30 according to the first embodiment.

[0147] (Laminate according to the third embodiment) Next, a laminate 30 according to a third embodiment will be described. The laminate 30 according to the third embodiment is substantially the same as the laminate 30 according to the second embodiment shown in FIG. 7 except that it further includes a barrier layer 80 provided on at least one of the first substrate 41 and the second substrate 51. In the laminate 30 according to the third embodiment, the same parts as those in the laminate 30 according to the second embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. Furthermore, if it is clear that the effects obtained in the first or second embodiment can also be obtained in the third embodiment, the description thereof may be omitted.

[0148] FIG. 8 is a cross-sectional view showing an example of the laminate 30 in the third embodiment. In the example shown in FIG. 8, the laminate 30 includes a barrier layer 80 provided on the surface of the first base material 41 on the inner surface 30x side. FIG. 9 is a cross-sectional view showing another example of the laminate 30 constituting the front surface film 14 and the back surface film 15 in the third embodiment. In the example shown in FIG. 9, the laminate 30 includes a barrier layer 80 provided on the surface of the second base material 51 on the outer surface 30y side. Therefore, the laminate 30 according to the third embodiment includes the barrier layer 80 provided on the surface of the second base material 51 on the outer surface 30y side in order from the outer surface side to the inner surface side. First substrate / barrier layer / first adhesive layer / second substrate / second adhesive layer / sealant layer, or First substrate / first adhesive layer / barrier layer / second substrate / second adhesive layer / sealant layer It can be said that the barrier layer 42 is provided with the above-mentioned pattern printed layer 43. Although not shown, the pattern printed layer 43 may be provided between the barrier layer and the first adhesive layer.

[0149] [Barrier layer] The barrier layer 80 will now be described.

[0150] [Transparent vapor deposition layer] As shown in FIGS. 8 and 9, the barrier layer 80 includes at least a transparent vapor deposition layer 81. The transparent vapor deposition layer 81 is provided on the first substrate 41 as shown in FIG. 8, or on the second substrate 51 as shown in FIG. 9. The transparent vapor deposition layer 81 is a layer made of a vapor deposition layer that can be formed by a conventionally known method. The provision of the transparent vapor deposition layer 81 can impart or improve gas barrier properties that prevent the permeation of oxygen gas, water vapor, and the like. The barrier layer 80 may include two or more transparent vapor deposition layers 81. When the barrier layer 80 includes two or more transparent vapor deposition layers 81, the layers may have the same composition or different compositions.

[0151] Transparent vapor deposition layer 81 is made of a vapor deposition layer of an inorganic oxide. For example, a vapor deposition layer of an oxide of silicon (Si), aluminum (Al), magnesium (Mg), calcium (Ca), potassium (K), tin (Sn), sodium (Na), boron (B), titanium (Ti), lead (Pb), zirconium (Zr), yttrium (Y), or the like can be used as transparent vapor deposition layer 81. In particular, it is preferable to provide a vapor deposition layer of aluminum oxide or silicon oxide.

[0152] Inorganic oxides are expressed as, for example, SiO X , AlO X MO etc. X(wherein, M represents an inorganic element, and the value of X varies depending on the inorganic element.) The value of X can range from 0 to 2 for silicon (Si), 0 to 1.5 for aluminum (Al), 0 to 1.5 for magnesium (Mg), 0 to 1 for calcium (Ca), 0 to 1 for potassium (K), 0 to 0.5 for tin (Sn), 0 to 2 for sodium (Na), 0 to 0.5 for boron (B), 0 to 1.5 for titanium (Ti), 0 to 2 for lead (Pb), 0 to 2 for zirconium (Zr), and 0 to 1.5 for yttrium (Y). In the above, when X=0, it is a completely inorganic element (pure substance) and is not transparent, and the upper limit of the range of X is the value when it is completely oxidized. Silicon (Si) and aluminum (Al) are preferably used for packaging materials, with silicon (Si) having a value in the range of 1.0 to 2.0 and aluminum (Al) having a value in the range of 0.5 to 1.5.

[0153] Transparent vapor deposition layer 81 may be a layer made of a mixture of inorganic compounds containing a covalent bond between an aluminum atom and a carbon atom. In this case, transparent vapor deposition layer 81 exhibits the presence of a covalent bond between an aluminum atom and a carbon atom in a peak measured by ion etching in the depth direction using an X-ray photoelectron spectrometer (measurement conditions: X-ray source AlKα, X-ray output 120 W), and may also have transparency and gas barrier properties that prevent the permeation of oxygen, water vapor, etc.

[0154] A covalent bond between a metal atom and a carbon atom may be formed at the interface between the transparent vapor deposition layer 81 and the first substrate 41 or the second substrate 51. For example, if the transparent vapor deposition layer 81 contains aluminum oxide, a covalent bond between an aluminum atom and a carbon atom may be formed at the interface between the transparent vapor deposition layer 81 and the first substrate 41 or the second substrate 51. The covalent bond can be detected by X-ray photoelectron spectroscopy (hereinafter abbreviated as "XPS measurement").

[0155] Furthermore, in the transparent vapor deposition layer 81, the abundance ratio of covalent bonds between aluminum atoms and carbon atoms is preferably within a range of 0.3% to 30% of all bonds including carbon atoms observed when the interface with the first substrate 41 or the second substrate 51 is measured by XPS. This strengthens the adhesion between the transparent vapor deposition layer 81 and the first substrate 41 or the second substrate 51, and provides a vapor deposition film with excellent transparency and well-balanced gas barrier properties.

[0156] If the proportion of covalent bonds between aluminum atoms and carbon atoms is less than 0.3%, the improvement in the adhesion of the transparent vapor-deposited layer 81 is insufficient, making it difficult to stably maintain the barrier properties.

[0157] Furthermore, it is preferable that the AL (aluminum) / O (oxygen) ratio of the transparent vapor deposition layer 81, which is mainly composed of aluminum oxide, is 1.0 or less within a range of up to 3 nm from the interface between the first substrate 41 or the second substrate 51 and the transparent vapor deposition layer 81 toward the surface of the transparent vapor deposition layer 81 on the opposite side from the first substrate 41 or the second substrate 51. If the AL / O ratio exceeds 1.0 within the range from the interface between the transparent vapor deposition layer 81 and the first substrate 41 or the second substrate 51 toward the surface of the transparent vapor deposition layer 81 opposite the first substrate 41 or the second substrate 51, the adhesion between the transparent vapor deposition layer 81 and the surface of the first substrate 41 or the second substrate 51 facing the transparent vapor deposition layer 81 becomes insufficient, and the proportion of aluminum increases, reducing the transparency of the transparent vapor deposition layer 81.

[0158] The thickness of the transparent vapor-deposited layer 81 varies depending on the type of inorganic oxide used, but is preferably selected from the range of 50 to 2000 Å, and more preferably 100 to 1000 Å. For example, in the case of a vapor-deposited layer of aluminum oxide or silicon oxide, the thickness is preferably 50 to 500 Å, and even more preferably 100 to 300 Å.

[0159] The transparent vapor deposition layer 81 can be formed on the first substrate 41 or the second substrate 51 using the following formation methods. Examples of methods for forming a vapor deposition layer include physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating, and chemical vapor deposition (CVD) methods such as plasma enhanced chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition. Specifically, a roller-type vapor deposition film formation device can be used to form a vapor deposition layer on a film formation roller.

[0160] In particular, when a covalent bond between a metal atom and a carbon atom is formed at the interface between the transparent vapor deposition layer 81 and the first substrate 41 or the second substrate 51, a pretreatment is performed on the surface of the first substrate 41 or the second substrate 51 on which the transparent vapor deposition layer 81 is to be formed. The pretreatment can be performed by supplying plasma to the surface of the first substrate 41 or the second substrate 51 in a reduced pressure environment of 0.1 Pa or more and 100 Pa or less using a pretreatment device. Plasma can be generated by using an inert gas such as argon alone or a mixture of oxygen, nitrogen, carbon dioxide, or one or more of these gases as a plasma raw material gas and exciting the plasma raw material gas with a potential difference such as a high-frequency voltage.

[0161] The pretreatment allows plasma to be confined near the surface of the first substrate 41 or the second substrate 51. This changes the surface shape, chemical bonding state, and functional groups of the substrate, thereby changing the chemical properties of the surface of the substrate. This makes it possible to improve the adhesion between the first substrate 41 or the second substrate 51 and the transparent vapor deposition layer 81 when the vapor deposition layer is formed.

[0162] [Gas barrier coating film] The barrier layer 80 may further include a gas barrier coating film 82. The gas barrier coating film 82 is provided on the surface of the transparent vapor deposition layer 81. The gas barrier coating film 82 is a coating film that functions as a layer that suppresses the permeation of oxygen gas, water vapor, and the like. The gas barrier coating film 82 is a coating film that functions as a layer that suppresses the permeation of oxygen gas, water vapor, and the like, represented by the general formula R1 n M(OR 2 ) m (wherein, R 1 , R 2 represents an organic group having 1 to 8 carbon atoms, M represents a metal atom, n represents an integer of 0 or more, m represents an integer of 1 or more, and n+m represents the valence of M. The gas barrier composition contains at least one alkoxide represented by the formula (I) above, and a polyvinyl alcohol resin and / or an ethylene-vinyl alcohol copolymer, and is further obtained by polycondensation by a sol-gel method in the presence of a sol-gel catalyst, an acid, water, and an organic solvent.

[0163] The general formula R 1 n M(OR 2 ) m As the alkoxide represented by the formula (I), at least one of a partial hydrolyzate of an alkoxide and a condensate of the hydrolysis of an alkoxide can be used. In addition, the partial hydrolyzate of the alkoxide does not necessarily have to have all of the alkoxy groups hydrolyzed, and may be one in which one or more alkoxy groups are hydrolyzed, or a mixture thereof. As the condensate of the hydrolysis of an alkoxide, a dimer or higher of the partially hydrolyzed alkoxide, specifically a dimer to hexamer, is used.

[0164] The general formula R 1 n M(OR 2 ) m In the alkoxide represented by the formula (I), silicon, zirconium, titanium, aluminum, and the like can be used as the metal atom represented by M. In this embodiment, preferred metals include silicon and titanium. In addition, in the present invention, the alkoxide can be used alone or by mixing two or more alkoxides of different metal atoms in the same solution.

[0165] In addition, the above general formula R 1 n M(OR 2 ) mIn the alkoxide represented by the formula 1 Specific examples of the organic group represented by the general formula R include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl, n-hexyl, n-octyl, and the like. 1 n M(OR 2 ) m In the alkoxide represented by the formula 2 Specific examples of the organic group represented by the formula (I) include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a sec-butyl group, etc. These alkyl groups may be the same or different in the same molecule.

[0166] When preparing the gas barrier composition, for example, a silane coupling agent may be added. A known organoalkoxysilane containing an organic reactive group can be used as the silane coupling agent. In this embodiment, an organoalkoxysilane having an epoxy group is particularly preferably used. Specific examples that can be used include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. The above-mentioned silane coupling agents may be used alone or in combination of two or more.

[0167] (Effects of this embodiment) In the present embodiment, the laminate 30 includes a barrier layer 80 provided on at least one of the first base material 41 and the second base material 51. This allows the gas barrier properties of the bag 10 formed from the laminate 30 to be improved.

[0168] (Laminate according to the fourth embodiment) In the second embodiment, a layer structure in which the laminate 30 includes a light-shielding printed layer 42 has been described, and in the third embodiment, a layer structure in which the laminate 30 includes a barrier layer 80 has been described, but these can also be combined and applied. Fig. 10 is a cross-sectional view showing an example of a laminate 30 in a fourth embodiment. The laminate 30 according to the fourth embodiment has the following layers in order from the outer surface side to the inner surface side: First substrate / barrier layer / light-shielding printed layer / first adhesive layer / second substrate / second adhesive layer / sealant layer It can be said that the barrier layer has the above-mentioned features. Note that " / " indicates the boundary between layers. Although not shown, the above-mentioned picture printed layer may be provided between the barrier layer and the light-blocking printed layer. [Example]

[0169] Next, the present invention will be explained in more detail with reference to examples. However, the present invention is not limited to the following examples as long as it does not depart from the gist of the present invention.

[0170] First, the puncture strength, total light transmittance, and odor barrier property of the laminate 30 of the present invention were evaluated using Examples 1 to 4 and Comparative Examples 1 and 2.

[0171] Example 1 A film-like first substrate 41 including multiple layers 41a and produced by a casting method, as described in the first configuration above, was prepared. The PBT content in each layer 41a was 80%, the number of layers 41a was 1024, and the thickness of the first substrate 41 was 15 μm. Next, a picture-printed layer 43 was formed on the film-like first substrate 41 using Finart manufactured by DIC Graphics Corporation. Next, a light-shielding printed layer 42 was formed on the picture-printed layer 43. The light-shielding printed layer 42 included a solid white layer and a solid gray layer laminated in this order on the picture-printed layer 43.

[0172] The solid white layer was formed by solid printing two times with white ink on the substrate by gravure printing. The first solid white layer was formed by solid printing a white ink (manufactured by Toyo Ink Co., Ltd., product name "Finestar 681AT") on the picture print layer 43. The second solid white layer was formed by solid printing a white ink (manufactured by Toyo Ink Co., Ltd., product name "NKFS R69K") on the first solid white layer. The thickness of the first solid white layer was 1 μm, and the thickness of the second solid white layer was 1.5 μm. A plate cylinder with a plate depth of 28 μm and a plate line count of 175 was used to form the solid white layer. The gray solid layer was formed by printing a single solid layer on the white solid layer with a gray ink mixture of white ink (manufactured by Toyo Ink Co., Ltd., product name "R631AT") and black ink (manufactured by Toyo Ink Co., Ltd., product name "N800LPGT Sumi") in a 6:4 ratio. A plate cylinder with a plate depth of 22 μm and a line count of 175 was used to form the gray solid layer. The thickness of the gray solid layer was 1.5 μm.

[0173] Also, a film-like second film 50 was prepared that included a second base material 51. The second base material 51 contained 100% by mass of PET. The thickness of the second base material 51 was 12 μm.

[0174] Also, a film-like third film 60 was prepared including a sealant layer 61. As the sealant layer 61, a non-stretched polypropylene film ZK207 manufactured by Toray Advanced Film Co., Ltd. was used. The thickness of the sealant layer 61 was 60 μm.

[0175] Next, the first film 40 and the second film 50 were laminated together by dry lamination with the first adhesive layer 45 interposed therebetween. A two-component polyurethane adhesive (main agent: RU-40, curing agent: H-4) manufactured by Rock Paint Co., Ltd. was used as the first adhesive layer 45. RU-40 contains polyester polyol. H-4 contains an aliphatic isocyanate compound. The thickness of the first adhesive layer 45 was 3 μm.

[0176] Next, the laminate of the first film 40 and the second film 50 and the third film 60 were laminated by dry lamination to obtain the laminate 30. As with the first adhesive layer 45, a two-component polyurethane adhesive (main agent: RU-40, curing agent: H-4) manufactured by Rock Paint Co., Ltd. was used for the second adhesive layer 55. The thickness of the second adhesive layer 55 was 3 μm.

[0177] Next, the puncture strength of the laminate 30 was measured in accordance with JIS Z1707 7.4. A Tensilon universal material testing machine RTC-1310 manufactured by A&D was used as the measuring instrument. Specifically, as shown in FIG. 5 , a test piece of the laminate 30 in a fixed state was pierced from the outer surface 30y side with a semicircular needle 70 having a diameter of 1.0 mm and a tip radius of 0.5 mm at a speed of 50 mm / min (50 mm per minute), and the maximum stress until the needle 70 penetrated the laminate 30 was measured. The maximum stress was measured for five or more test pieces, and the average value was taken as the puncture strength of the laminate 30. The measurement was performed in an environment of 23°C and 50% relative humidity. The resulting puncture strength was 17 N.

[0178] Next, the light-blocking property of the laminate 30 was evaluated. Specifically, the total light transmittance of the laminate 30 was measured when light was incident on the outer surface 30y of the laminate 30. The measuring device used was a haze meter HM-150, a total light transmittance measuring device manufactured by Murakami Color Research Laboratory Co., Ltd. As a result, the total light transmittance was 9%.

[0179] Next, the odor barrier properties of the laminate 30 were evaluated. Specifically, the inner surfaces 30x of two laminates 30 were sealed together to form a bag, and the bag was heated and then opened to evaluate whether or not an odor was detected. The dimensions of the two laminates 30 were 100 mm in length and 100 mm in width, respectively. The bag shape was a four-sided sealed bag. The bag was heated for one minute in an oven controlled at 40°C. As a result, no odor was detected.

[0180] Example 2 The laminate 30 was produced in the same manner as in Example 1, except that the first substrate 41 of the first film 40 was a single-layer film produced by the tubular method, containing 100% by mass of PBT, with a melting point of 224°C and an IV value of 1.26 dl / g, as described in the second configuration above. The first substrate 41 was a single-layer film composed only of PBT and additives, and had a thickness of 15 μm.

[0181] Next, the puncture strength of the laminate 30 was measured in the same manner as in Example 1. As a result, the puncture strength was 17 N. Furthermore, the total light transmittance of the laminate 30 was measured in the same manner as in Example 1. As a result, the total light transmittance was 9%. Furthermore, the odor barrier property of the laminate 30 was evaluated in the same manner as in Example 1. As a result, no unpleasant odor was detected.

[0182] Example 3 The laminate 30 was produced in the same manner as in Example 1, except that the PBT constituting the first substrate 41 in Example 1 was used as the second substrate 51, and the PET constituting the second substrate 51 in Example 1 was used as the first substrate 41.

[0183] Next, the puncture strength of the laminate 30 was measured in the same manner as in Example 1. As a result, the puncture strength was 17 N. Furthermore, the total light transmittance of the laminate 30 was measured in the same manner as in Example 1. As a result, the total light transmittance was 9%. Furthermore, the odor barrier property of the laminate 30 was evaluated in the same manner as in Example 1. As a result, no unpleasant odor was detected.

[0184] Example 4 The laminate 30 was produced in the same manner as in Example 1, except that the PBT constituting the first substrate 41 in Example 2 was used as the second substrate 51, and the PET constituting the second substrate 51 in Example 2 was used as the first substrate 41.

[0185] Next, the puncture strength of the laminate 30 was measured in the same manner as in Example 1. As a result, the puncture strength was 17 N. Furthermore, the total light transmittance of the laminate 30 was measured in the same manner as in Example 1. As a result, the total light transmittance was 9%. Furthermore, the odor barrier property of the laminate 30 was evaluated in the same manner as in Example 1. As a result, no unpleasant odor was detected.

[0186] (Comparative Example 1) The laminate 30 was produced in the same manner as in Example 1, except that a base material containing 100% by mass of PET was used as the first base material 41 of the first film 40. The thickness of the first base material 41 was 12 μm.

[0187] Next, the puncture strength of the laminate 30 was measured in the same manner as in Example 1. As a result, the puncture strength was 12 N. Furthermore, the total light transmittance of the laminate 30 was measured in the same manner as in Example 1. As a result, the total light transmittance was 10%. Furthermore, the odor barrier property of the laminate 30 was evaluated in the same manner as in Example 1. As a result, no unpleasant odor was detected.

[0188] (Comparative Example 2) A laminate 30 was produced in the same manner as in Comparative Example 1, except that a nylon film (Bonyl W, manufactured by Kojin Holdings Co., Ltd.) having a thickness of 15 μm was used as the second substrate 51 of the second film 50.

[0189] Next, the puncture strength of the laminate 30 was measured in the same manner as in Example 1. As a result, the puncture strength was 17 N. Furthermore, the total light transmittance of the laminate 30 was measured in the same manner as in Example 1. As a result, the total light transmittance was 10%. Furthermore, the odor barrier property of the laminate 30 was evaluated in the same manner as in Example 1. As a result, an unpleasant odor was detected.

[0190] The layer structures and evaluation results of the laminates of Examples 1 to 4 and Comparative Examples 1 and 2 are summarized in FIG. 6. In FIG. 6, the "Layer Structure" column lists the components of the laminate, excluding the adhesive layer, in order from the outermost layer to the top. As can be seen from a comparison between Examples 1 to 4 and Comparative Example 1, when the first substrate 41 or the second substrate 51 contains PBT, higher puncture strength was achieved compared to when both the first substrate 41 and the second substrate 51 contain PET. Furthermore, as can be seen from a comparison between Examples 1 to 4 and Comparative Example 2, when a material other than nylon, specifically PBT or PET, is used as the second substrate 51, better light-blocking and odor-barrier properties were achieved compared to when the second substrate 51 contains nylon.

[0191] Next, the piercing strength and coloring resistance of the laminate 30 of the present invention were evaluated using Examples 5 to 8 and Comparative Examples 3 and 4.

[0192] Example 5 The laminate 30 was produced in the same manner as in Example 1, except that the light-shielding printed layer 42 and the picture printed layer 43 were not provided.

[0193] Subsequently, the piercing strength of the laminate 30 was measured in the same manner as in Example 1. As a result, the piercing strength was 17N.

[0194] Next, the coloring resistance of the laminate 30 was evaluated. Specifically, the inner surfaces 30x of two laminates 30 were sealed together to prepare a bag containing commercially available curry as the content. Next, the bag was subjected to a retort treatment, and then opened to visually evaluate whether or not the laminate 30 constituting the bag was colored. The dimensions of each of the two laminates 30 were 100 mm in length and 100 mm in width. The bag shape was a four-sided sealed bag. The retort treatment of the bag was performed using a hot water method at 121°C for 30 minutes. As a result, no coloring was observed.

[0195] Example 6 The laminate 30 was produced in the same manner as in Example 5, except that the first substrate 41 of the first film 40 was a single-layer film produced by the tubular method, containing 100% by mass of PBT, with a melting point of 224°C and an IV value of 1.26 dl / g, as described in the second configuration above. The first substrate 41 was a single-layer film composed only of PBT and additives, and had a thickness of 15 μm.

[0196] Subsequently, the piercing strength of the laminate 30 was measured in the same manner as in Example 1. As a result, the piercing strength was 17 N. Furthermore, the coloration resistance of the laminate 30 was evaluated in the same manner as in Example 5. As a result, no coloration was observed.

[0197] Example 7 The laminate 30 was produced in the same manner as in Example 5, except that the PBT constituting the first substrate 41 in Example 5 was used as the second substrate 51, and the PET constituting the second substrate 51 in Example 5 was used as the first substrate 41.

[0198] Subsequently, the piercing strength of the laminate 30 was measured in the same manner as in Example 1. As a result, the piercing strength was 16 N. Furthermore, the coloration resistance of the laminate 30 was evaluated in the same manner as in Example 5. As a result, no coloration was observed.

[0199] Example 8 The laminate 30 was produced in the same manner as in Example 5, except that the PBT constituting the first substrate 41 in Example 6 was used as the second substrate 51, and the PET constituting the second substrate 51 in Example 6 was used as the first substrate 41.

[0200] Subsequently, the piercing strength of the laminate 30 was measured in the same manner as in Example 1. As a result, the piercing strength was 16 N. Furthermore, the coloration resistance of the laminate 30 was evaluated in the same manner as in Example 5. As a result, no coloration was observed.

[0201] (Comparative Example 3) The laminate 30 was produced in the same manner as in Example 5, except that a base material containing 100% by mass of PET was used as the first base material 41 of the first film 40. The thickness of the first base material 41 was 12 μm.

[0202] Subsequently, the piercing strength of the laminate 30 was measured in the same manner as in Example 5. As a result, the piercing strength was 11 N. Furthermore, the coloration resistance of the laminate 30 was evaluated in the same manner as in Example 5. As a result, no coloration was observed.

[0203] Comparative Example 4 The laminate 30 was produced in the same manner as in Comparative Example 3, except that a nylon film (Bonyl W manufactured by Kojin Holdings Co., Ltd.) having a thickness of 15 μm was used as the second substrate 51 of the second film 50.

[0204] Subsequently, the piercing strength of the laminate 30 was measured in the same manner as in Example 5. As a result, the piercing strength was 17 N. Furthermore, the coloration resistance of the laminate 30 was evaluated in the same manner as in Example 5. As a result, coloration was observed.

[0205] The layer structures and evaluation results of the laminates of Examples 5 to 8 and Comparative Examples 3 and 4 are summarized in FIG. 11. In FIG. 11, the "Layer Structure" column lists the components of the laminate, excluding the adhesive layer, in order from the outermost layer to the top. As can be seen from a comparison between Examples 5 to 8 and Comparative Example 3, when the first substrate 41 or the second substrate 51 contains PBT, higher puncture strength was achieved compared to when both the first substrate 41 and the second substrate 51 contain PET. Furthermore, as can be seen from a comparison between Examples 5 to 8 and Comparative Example 4, when a material other than nylon, specifically PBT or PET, is used as the second substrate 51, better color resistance was achieved compared to when the second substrate 51 contains nylon. [Explanation of symbols]

[0206] 10 bags 11 Upper 12 Lower 12a Lower seal 13 Side 13a Side seal 14 Surface film 15 Back film 16 Lower film 17 Storage section 25 Easy-to-open means 26 Notch 27 Opening schedule 30 laminate 40 First Film 41 First base material 41a layer 42 Light-shielding printing layer 43 Picture printing layer 45 First adhesive layer 50 2nd Film 51 Second base material 55 Second adhesive layer 60 Third Film 61 Sealant layer 80 Barrier Layer 81 Transparent vapor deposition layer 82 Gas barrier coating film

Claims

1. A laminate, The adhesive sheet includes at least a first substrate, a first adhesive layer, a second substrate, a second adhesive layer, and a sealant layer in this order; the second substrate contains 51% by mass or more of polyethylene terephthalate or 51% by mass or more of polybutylene terephthalate, When the second substrate contains 51% by mass or more of polyethylene terephthalate, the first substrate contains 51% by mass or more of polybutylene terephthalate, When the second substrate contains 51% by mass or more of polybutylene terephthalate, the first substrate contains 51% by mass or more of polyethylene terephthalate, Of the first substrate and the second substrate, the substrate containing 51 mass % or more of polybutylene terephthalate has a multilayer structure including 10 or more layers, The substrate containing 51% by mass or more of polybutylene terephthalate among the first substrate and the second substrate is a biaxially stretched film, the sealant layer comprises 80% by mass or more of a propylene-ethylene block copolymer, polyethylene, and an ethylene-α-olefin elastomer; The polyethylene is one or more selected from low-density polyethylene and linear low-density polyethylene, A laminate having a puncture strength of 13 N or more.

2. The laminate according to claim 1 , wherein the substrate containing 51% by mass or more of polybutylene terephthalate out of the first substrate and the second substrate has a multilayer structure including 250 or more layers.

3. The laminate according to claim 1 , wherein the substrate containing 51% by mass or more of polybutylene terephthalate out of the first substrate and the second substrate has a multilayer structure including 1000 or more layers.

4. 4. The laminate according to claim 1, wherein the polyethylene of the sealant layer has a melting point of 100°C or higher.

5. The laminate according to claim 1 , further comprising a light-blocking printed layer located between the first substrate and the second substrate.

6. The laminate according to claim 5 , wherein the thickness of the light-shielding printed layer is 2 μm or more.

7. The laminate according to claim 5 or 6, wherein the light-shielding printed layer contains a chromatic ink.

8. The laminate according to claim 5 or 6, wherein the light-shielding printed layer contains achromatic ink.

9. The laminate according to claim 5 , further comprising a picture print layer located on an outer surface side of the laminate relative to the light-shielding print layer.

10. The laminate according to claim 5 , wherein the laminate has a total light transmittance of 20% or less.

11. 11. The laminate according to claim 1, further comprising a barrier layer between the first substrate and the second substrate, the barrier layer including at least a transparent vapor deposition layer provided on at least one of the first substrate or the second substrate.

12. The laminate of claim 11 , wherein the transparent vapor-deposited layer comprises aluminum oxide.

13. The laminate according to claim 11 or 12, wherein the barrier layer further comprises a gas barrier coating film provided on a surface of the transparent vapor deposition layer.

14. A bag, The laminate according to any one of claims 1 to 13, a seal portion that joins the inner surfaces of the laminate together.

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