Film for package, package, and method for producing film for package

Abstract

To provide a film for a package that is excellent in various functions and can be easily recycled.SOLUTION: A film for a package comprises a sealant material and a base material of biaxially-stretched polypropylene positioned on one side of the sealant material. The sealant material has a support layer of biaxially-stretched polypropylene and a skin layer of polypropylene. The skin layer forms the other side of the sealant material. The base material has a heat quantity ratio at an endothermic peak derived from α-crystal of 60% or higher with respect to the total heat quantity at an endothermic peak of the base material. The skin layer has a heat quantity ratio at an endothermic peak derived from β-crystal of 2.0% or higher with respect to the total heat quantity at an endothermic peak of the skin layer. At least one of the sealant material and the base material has an inorganic deposition layer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a film for a package, a package, and a method for manufacturing a film for a package.

Background Art

[0002] A package is required to have a function of suppressing deterioration of the contents. In addition, the package is required to have a strength (impact resistance) that does not easily break the bag when an external force is applied. For this reason, the film for a package is required to have oxygen barrier properties, water vapor barrier properties, impact resistance, rigidity from the viewpoint of facilitating handling during bag making, and seal strength.

[0003] In response to such problems, for example, Patent Document 1 proposes a film for a package including a gas barrier coating film provided on an unstretched polyolefin resin film and an aluminum vapor deposition layer provided on the gas barrier coating film. In the invention of Patent Document 1, it has oxygen barrier properties, water vapor barrier properties, light shielding properties, and glossiness equivalent to those of aluminum vapor-deposited polyethylene terephthalate (aluminum vapor-deposited PET), and the adhesion and heat sealability are improved.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the invention of Patent Document 1, since various functions such as oxygen barrier properties, water vapor barrier properties, rigidity, impact resistance, and seal strength are imparted by combining a plurality of materials having different characteristics, there is a problem that recycling is difficult. In order to improve the recyclability, simply making it a single material (monomaterial) has a problem that various functions cannot be sufficiently enhanced.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a film for a package that is excellent in various functions and can be easily recycled.

Means for Solving the Problems

[0007] It is known that the crystal structure of polypropylene includes α-crystals (also called monoclinic crystals) and β-crystals (also called hexagonal crystals). The β-crystals include β'-crystals (also called β-prime crystals, pseudo-hexagonal crystals) derived from the β-crystals. As a result of intensive studies, the inventors of the present invention have found that in a laminate of polypropylene, by specifying the crystal structure of each layer and providing a vapor deposition layer at a specific position, various functions can be enhanced while being monolithic, and thus the present invention has been completed. That is, the film for a package of the present invention has the following configuration. <1> It has a sealant material and a base material of biaxially stretched polypropylene located on one surface of the sealant material, The sealant material has a support layer of stretched polypropylene and a skin layer of polypropylene, The skin layer forms the other surface of the sealant material, In the base material, the heat quantity ratio of the endothermic peak derived from α-crystals is 60% or more with respect to the total heat quantity of the endothermic peak of the base material, In the skin layer, the heat quantity ratio of the endothermic peak derived from β-crystals is 2.0% or more with respect to the total heat quantity of the endothermic peak of the skin layer, A film for a package, wherein at least one of the sealant material and the base material has an inorganic vapor deposition layer. <2> The film for a package according to <1>, having a thickness of 30 to 120 μm. <3> The thickness of the sealant material is 20 to 100 μm, The film for a package according to <1> or <2>, wherein the thickness of the skin layer is 2 to 30 μm.

[0008] <4> A package formed by bag-making a film for a package according to any one of <1> to <3>.

[0009] <5> A method for manufacturing a film for a package, comprising a sealant material and a base material of biaxially stretched polypropylene located on one surface of the sealant material, the sealant material having a support layer of biaxially stretched polypropylene and a skin layer of polypropylene, the skin layer forming the other surface of the sealant material, and at least one of the sealant material and the base material having an inorganic vapor deposition layer, the method comprising: A lamination step of laminating the sealant material and the base material; A first heat treatment step of subjecting the base material to a first heat treatment so that a heat quantity ratio of an endothermic peak derived from α crystals in the base material is 60% or more with respect to a total heat quantity of endothermic peaks of the base material; A second heat treatment step of subjecting the skin layer to a second heat treatment so that a heat quantity ratio of an endothermic peak derived from β crystals in the skin layer is 2.0% or more with respect to a total heat quantity of endothermic peaks of the skin layer. <6> The method for manufacturing a film for a package according to <5>, wherein the second heat treatment step is performed after the lamination step. [Advantages of the Invention]

[0010] According to the film for a package of the present invention, it is excellent in various functions and can be easily recycled. [Brief Description of the Drawings]

[0011]

Figure 1

Figure 2

Figure 3

[0012] [Film for Package] The film for a package of the present invention has a polypropylene sealant material and a base material of biaxially stretched polypropylene located on one surface of the sealant material. In the film for a package of the present invention, the resin of the base material and the resin of the sealant material are of the same type (polypropylene). Therefore, when recovering the film for a package of the present invention, it is not necessary to separate the base material and the sealant material, and it can be easily recycled.

[0013] The film for a package according to an embodiment of the present invention will be described with reference to the drawings. The film 1 for a package in FIG. 1 is formed by laminating a base material 10, an adhesive layer 30, and a sealant material 20 in this order. That is, the film 1 for a package has a sealant material 20 and a base material located on one surface of the sealant material 20 via an adhesive layer 30. Note that when the base material 10 and the sealant material 20 can be fused, the adhesive layer 30 may not be provided.

[0014] The sealant material 20 has a support layer 24 and a skin layer 22. The skin layer 22 forms the other surface of the sealant material 20 (the surface opposite to the adhesive layer 30). That is, the film 1 for a package has a base material 10, an adhesive layer 30, a support layer 24, and a skin layer 22 in this order. The base material 10 has an inorganic vapor deposition layer 12 on the surface facing the adhesive layer 30. In the present embodiment, the base material 10 has the inorganic vapor deposition layer 12, but the present invention is not limited thereto, and the sealant material 20 may have an inorganic vapor deposition layer, or both the base material 10 and the sealant material 20 may have an inorganic vapor deposition layer. In the present embodiment, the inorganic vapor deposition layer 12 is located on the surface facing the adhesive layer 30, but the position of the inorganic vapor deposition layer is not limited thereto. The inorganic vapor deposition layer 12 may be located on the surface opposite to the adhesive layer 30. However, from the viewpoint of further enhancing the oxygen barrier property and the water vapor barrier property, it is preferable that the inorganic vapor deposition layer is located on at least one of the surface of the base material 10 facing the adhesive layer 30 and the surface of the sealant material 20 facing the adhesive layer 30.

[0015] The oxygen permeability of the film 1 for the package is preferably 4.0 mL / (m 2 ·day) or less, more preferably 2.0 mL / (m 2 ·day) or less, and even more preferably 1.0 mL / (m 2 ·day) or less. When the oxygen permeability of the film 1 for the package is equal to or less than the above upper limit value, the deterioration of the contents can be suppressed better. The lower the oxygen permeability of the film 1 for the package, the more preferable it is. The lower limit value of the oxygen permeability is preferably 0 mL / (m 2 ·day). In this article, the oxygen permeability can be measured according to the test method for oxygen gas permeability by the electrolytic sensor method described in Appendix A of JIS K7126-2:2006. The oxygen permeability of the film 1 for the package can be adjusted by the material and thickness of the base material 10, the material and thickness of the sealant material 20, the type and thickness of the inorganic vapor deposition layer 12 described later, the type and content of the oxygen absorber, and combinations thereof.

[0016] The water vapor permeability of the film 1 for the package is preferably 4.0 g / (m 2 ·day) or less, more preferably 2.0 g / (m 2 ·day) or less, and even more preferably 1.0 g / (m 2 ·day) or less. When the water vapor permeability of the base material 10 is equal to or less than the above upper limit value, the deterioration of the contents can be suppressed better. The lower the water vapor permeability, the more preferable it is. The lower limit value of the water vapor permeability is preferably 0 g / (m 2 ·day). The water vapor permeability can be measured according to the test method described in the humidity sensor method of JIS K7129:2008 under test condition 1 described in Table A.1. The water vapor permeability can be adjusted by the material and thickness of the base material 10, the material and thickness of the sealant material 20, the tensile elastic modulus in the MD direction, the tensile elastic modulus in the TD direction, and combinations thereof.

[0017] The light transmittance of the film 1 for packaging at a wavelength of 450 nm of visible light (hereinafter, also simply referred to as "light transmittance") is preferably 20% or less, more preferably 10% or less, and even more preferably 4% or less. When the light transmittance of the film 1 for packaging is below the above upper limit value, the light shielding property can be enhanced. The smaller the light transmittance of the film 1 for packaging, the more preferable it is, and the lower limit value of the light transmittance is preferably 0%. The light transmittance of the film 1 for packaging can be measured, for example, using an ultraviolet-visible spectrophotometer. The light transmittance of the film 1 for packaging can be adjusted by the material and thickness of the sealant material 20, the thickness of the inorganic vapor deposition layer 12 described later, the type and content of the inorganic substance constituting the inorganic vapor deposition layer 12, and combinations thereof.

[0018] The tensile elastic modulus of the film 1 for packaging in the MD direction (the extrusion direction when manufacturing the film) is preferably 1.8 GPa or more, more preferably 1.9 GPa or more, and even more preferably 2.0 GPa or more. When the tensile elastic modulus of the film 1 for packaging in the MD direction is at or above the above lower limit value, the film 1 for packaging has excellent water vapor barrier properties. The upper limit value of the tensile elastic modulus of the film 1 for packaging in the MD direction is not particularly limited, but is, for example, 5.0 GPa. The tensile elastic modulus of the film 1 for packaging in the MD direction can be measured according to the test method described in JIS K7127:1999. The tensile elastic modulus of the film 1 for packaging in the MD direction can be adjusted by the material and thickness of the base material 10, the material and thickness of the sealant material 20, molding conditions (temperature during molding, cooling time, extrusion speed), etc.

[0019] The thickness T1 of the film 1 for packaging is appropriately determined in consideration of the use (for example, the size and capacity of the packaging body after bag making, etc.). The thickness T1 is preferably, for example, 30 to 120 μm, more preferably 40 to 80 μm, and even more preferably 50 to 60 μm. When the thickness T1 is at or above the above lower limit value, the strength and rigidity of the film 1 for packaging can be further enhanced. When the thickness T1 is at or below the above upper limit value, the flexibility of the film 1 for packaging can be further enhanced, and handling becomes easier. In this manuscript, the thickness is, for example, the average value of the values measured with a thickness gauge for 10 randomly selected points.

[0020] ≪Base material≫ The base material 10 is a biaxially stretched polypropylene film (biaxially stretched polypropylene film). By using a biaxially stretched polypropylene film as the base material 10, the water vapor barrier property of the film 1 for packaging can be enhanced. This is presumably because the crystallinity of polypropylene can be increased by stretching the polypropylene film. The "polypropylene film" refers to a film in which 50% by mass or more of the total mass of the resin is polypropylene. That is, the material of the base material 10 contains a resin containing 50% by mass or more of polypropylene. Examples of the polypropylene in the base material 10 include homopolypropylene, a copolymer of polypropylene containing about 10% by mass of polyethylene and polyethylene, and block polypropylene. The base material 10 may be a single layer or a multilayer in which two or more layers are laminated. When the base material 10 is a multilayer, the inorganic vapor deposition layer 12 may be located on the surface of the base material 10 or between the layers.

[0021] When the base material 10 is measured for heat quantity with a heat flux differential scanning calorimeter (hereinafter also referred to as a DSC device), an endothermic peak of the melting point of the crystals (α-crystals, β-crystals) of the base material 10 is observed. In this manuscript, β-crystals and β'-crystals are collectively referred to as β-crystals. The melting point of β-crystals (melting point of β-crystals = 145 to 150 °C, melting point of β'-crystals = 140 to 147 °C) is lower than the melting point of α-crystals (155 to 172 °C). When the base material 10 having β-crystals is treated at a high temperature (for example, 80 °C or higher), the crystals of β-crystals are in a state of transitioning to α-crystals. In this way, by observing the endothermic peak of the DSC curve obtained by performing heat flux differential scanning calorimetry (DSC measurement), the formation of α-crystals and β-crystals can be determined.

[0022] For example, in the case of the DSC curve shown in FIG. 2, curve C1 has a first endothermic peak P1 at 162.91° C. and a second endothermic peak P2 at 171.01° C. The endothermic peak P2 observed on the high temperature side is an endothermic peak derived from the melting point of the α crystal. The endothermic peak P1 observed on the low temperature side is a single peak and is considered to be an endothermic peak derived from the melting point of the β crystal. On the other hand, in the case of the DSC curve shown in FIG. 3, curve C2 has an endothermic peak P3 branched at 163.37° C. and 164.75° C., an endothermic peak P4 at 167.65° C., and an endothermic peak P5 at 170.99° C. The endothermic peak P5 observed on the high temperature side is an endothermic peak derived from the melting point of the α crystal. The plurality of endothermic peaks P3 and P4 observed on the low temperature side are considered to be endothermic peaks derived from the melting point of the β crystal (corresponding to the β' crystal). In this specification, when two or more endothermic peaks are observed in the DSC curve other than the endothermic peak derived from the melting point of the α crystal, it is determined that the two or more endothermic peaks are endothermic peaks derived from the melting point of the β crystal.

[0023] The measurement conditions for DSC measurement are as follows. An endothermic peak is observed from the DSC curve obtained during the first heating. The heat quantity ratio of each endothermic peak is obtained using the analysis software of the DSC apparatus based on the area of each endothermic peak. The heat quantity ratio of each endothermic peak is the average value obtained by performing DSC measurement twice on the same sample. (Measuring device) · Heat flux differential scanning calorimeter (DSC device): Differential scanning calorimeter, DSC-60Plus (manufactured by Shimadzu Corporation). (Measurement conditions) · Sample amount: 5.5 ± 0.5 mg. · Reference (alumina) amount: 5 mg. · Nitrogen gas flow rate: 20 mL / min. · Number of tests: 2. · First heating condition: Heat up from 40° C. to 200° C. at a heating rate of 10° C. / min. · Holding time: 0 min. · First cooling condition: Cool down from 200° C. to 50° C. at a cooling rate of -10° C. / min. ·Second heating condition: Heat from 50°C to 200°C at a heating rate of 10°C / min. ·Holding time: 0 min. ·Second cooling condition: Cool from 200°C to 50°C at a cooling rate of -10°C / min.

[0024] In the base material 10, the heat quantity ratio of the endothermic peak of the α crystal (α heat quantity ratio) to the total heat quantity of the endothermic peak of the base material 10 measured by a DSC device is 60% or more, preferably 70% or more, and more preferably 75% or more. When the α heat quantity ratio in the base material 10 is at or above the above lower limit value, the rigidity can be increased. The upper limit of the α heat quantity ratio in the base material 10 is preferably, for example, 99% or less, and more preferably 95% or less. When the α heat quantity ratio is at or below the above upper limit value, the adhesion with the sealant material 20 can be further enhanced. The α heat quantity ratio can be adjusted by the treatment temperature, treatment time, and their combination when heat-treating the base material 10. Note that the total heat quantity of the endothermic peak is the sum of the α heat quantity ratio and the heat quantity ratio of the β crystal.

[0025] In the base material 10, the heat quantity ratio of the endothermic peak of the β crystal (β heat quantity ratio) to the total heat quantity of the endothermic peak of the base material 10 measured by a DSC device is preferably 40% or less, more preferably 30% or less, and even more preferably 25% or less. When the β heat quantity ratio in the base material 10 is at or below the above upper limit value, the elastic modulus is increased and the rigidity can be further increased. The lower limit of the β heat quantity ratio in the base material 10 is, for example, substantially 10% or more. The β heat quantity ratio can be adjusted by the treatment temperature, treatment time, and their combination when heat-treating the base material 10.

[0026] Examples of the inorganic vapor deposition layer 12 include an aluminum vapor deposition layer and a silica vapor deposition layer. From the viewpoints of further improving the oxygen barrier property, further improving the water vapor barrier property, and improving the light shielding property, the aluminum vapor deposition layer is preferred as the inorganic vapor deposition layer 12.

[0027] The tensile elastic modulus of the base material 10 in the TD direction (direction perpendicular to the MD direction) is preferably 3.6 GPa or more, more preferably 3.7 GPa or more, and even more preferably 3.8 GPa or more. When the tensile elastic modulus of the base material 10 in the TD direction is at least the above lower limit value, the film 1 for packaging has excellent water vapor barrier properties. The upper limit value of the tensile elastic modulus of the base material 10 in the TD direction is not particularly limited, but is, for example, 7.0 GPa. The tensile elastic modulus of the base material 10 in the TD direction can be measured in the same manner as the tensile elastic modulus of the base material 10 in the MD direction. The tensile elastic modulus of the base material 10 in the TD direction can be adjusted by the material, thickness, and molding conditions (temperature during molding, cooling time, extrusion speed, etc.) of the base material 10.

[0028] The thickness T10 of the base material 10 is determined in consideration of the material, configuration, etc., and is preferably, for example, 18 to 30 μm, and more preferably 20 to 30 μm. When the thickness T10 of the base material 10 is at least the above lower limit value, the strength and rigidity of the film 1 for packaging can be further enhanced. In addition, when the thickness T10 of the base material 10 is at least the above lower limit value, the water vapor barrier properties of the film 1 for packaging can be further enhanced. When the thickness T10 of the base material 10 is at most the above upper limit value, the flexibility of the film 1 for packaging can be enhanced, making handling easier. The thickness T10 of the base material 10 is the average value of the values measured with a thickness gauge at 10 randomly selected points on the base material 10 peeled from the film 1 for packaging.

[0029] The thickness T12 of the inorganic vapor deposition layer 12 is preferably 20 to 100 nm, more preferably 35 to 85 nm, and even more preferably 50 to 70 nm. When the thickness T12 of the inorganic vapor deposition layer 12 is at least the above lower limit value, the oxygen barrier properties, water vapor barrier properties, and light shielding properties of the film 1 for packaging can be further enhanced. When the thickness T12 is at most the above upper limit value, the occurrence of delamination due to cohesive failure can be suppressed. Therefore, the impact resistance of the film 1 for packaging can be further enhanced. The thickness T12 is determined, for example, as the average value of 10 randomly selected points by observing the cut surface of the film 1 for packaging cut in the thickness direction with a microscope (for example, 200 times).

[0030] <<Sealing Material>> The sealing material 20 is a polyethylene film and has a support layer 24 and a skin layer 22 located on one surface of the support layer 24. The skin layer 22 forms a surface on the side opposite to the adhesive layer 30 (the other surface of the sealing material 20). By having the skin layer 22, the sealing strength of the sealing material 20 can be increased. The support layer 24 may be a single layer or a multi-layer of two or more layers. When the sealing material 20 of the film 1 for the package of the present embodiment has an inorganic vapor deposition layer, it is preferable that the inorganic vapor deposition layer is located on the surface facing the adhesive layer 30. By positioning the inorganic vapor deposition layer at such a position, the sealing strength can be further increased. When the support layer 24 is a multi-layer, the inorganic vapor deposition layer may be located on the surface of the support layer 24 or between the layers.

[0031] The support layer 24 is a biaxially stretched polypropylene film or a uniaxially stretched polypropylene film, or a combination thereof. That is, the support layer 24 is a stretched polypropylene film. By the support layer being a stretched polypropylene film, the rigidity of the film 1 for the package can be increased. The material of the polypropylene film of the support layer 24 is the same as the material of the biaxially stretched polypropylene film of the base material 10. The material of the biaxially stretched polypropylene film of the support layer 24 and the material of the biaxially stretched polypropylene film of the base material 10 may be the same or different.

[0032] The degree of orientation of the support layer 24 is preferably smaller than the degree of orientation of the base material 10. By the degree of orientation of the support layer 24 being smaller than the degree of orientation of the base material 10, it can be joined more firmly to the base material 10.

[0033] The skin layer 22 is a polypropylene film. Examples of the polypropylene film for the skin layer 22 include an unstretched polypropylene film, a uniaxially stretched polypropylene film, and a biaxially stretched polypropylene film. Among them, from the viewpoint of further improving the seal strength, the skin layer 22 is preferably a uniaxially stretched polypropylene film or an unstretched polypropylene film. The material of the polypropylene film of the skin layer 22 is the same as that of the biaxially stretched polypropylene film of the base material 10. The material of the polypropylene film of the skin layer 22 and the material of the biaxially stretched polypropylene film of the base material 10 may be the same or different.

[0034] The β heat quantity ratio of the skin layer 22 is 2.0% or more. The β heat quantity ratio of the skin layer 22 is the heat quantity ratio of the endothermic peak of β crystals (including β' crystals) to the total heat quantity of the endothermic peak of the skin layer 22 measured by a DSC device.

[0035] The β heat quantity ratio of the skin layer 22 is preferably 5.0% or more, more preferably 8.0% or more. When the β heat quantity ratio is equal to or higher than the above lower limit value, the seal strength can be further increased. The upper limit value of the β heat quantity ratio of the skin layer 22 is preferably 50% or less, more preferably 40% or less, for example. When the β heat quantity ratio of the skin layer 22 is equal to or lower than the above upper limit value, the elastic modulus is increased and the rigidity can be further increased. The β heat quantity ratio of the skin layer 22 can be adjusted by the material of the skin layer 22, the type of the film of the skin layer 22, the treatment temperature, the treatment time, and the combination thereof when heat treatment is performed by the manufacturing method described later.

[0036] The α heat quantity ratio of the skin layer 22 is not particularly limited. For example, it is preferably 95% or less, more preferably 92% or less. When the α heat quantity ratio of the skin layer 22 is equal to or lower than the above upper limit value, the rigidity can be further increased. The lower limit value of the α heat quantity ratio of the skin layer 22 is, for example, 40% or more.

[0037] The β heat quantity ratio of the skin layer 22 is preferably larger than that of the base material 10. The β heat quantity ratio of the skin layer 22 is preferably 5 points or more larger than that of the base material 10, and preferably 10 points or more larger. For example, when the β heat quantity ratio of the skin layer 22 is 10% and the β heat quantity ratio of the base material 10 is 5%, the difference between the β heat quantity ratio of the skin layer 22 and the β heat quantity ratio of the base material 10 is 5 points. When the difference between the β heat quantity ratio of the skin layer 22 and the β heat quantity ratio of the base material 10 is equal to or greater than the above lower limit value, the adhesion between the base material 10 and the sealant material 20 can be further enhanced. The upper limit value of the difference between the β heat quantity ratio of the skin layer 22 and the β heat quantity ratio of the base material 10 is substantially 20 points.

[0038] The α heat quantity ratio of the skin layer 22 is preferably smaller than that of the base material 10 (that is, the α heat quantity ratio of the base material 10 is larger than that of the skin layer 22). The α heat quantity ratio of the base material 10 is preferably 5.0 points or more larger than that of the skin layer 22, and preferably 10 points or more larger. When the difference between the α heat quantity ratio of the skin layer 22 and the α heat quantity ratio of the skin layer 22 is equal to or greater than the above lower limit value, the elastic modulus can be increased and the rigidity can be further enhanced. The upper limit value of the difference between the α heat quantity ratio of the skin layer 22 and the α heat quantity ratio of the base material 10 is substantially 20 points.

[0039] The α heat quantity ratio of the support layer 24 is not particularly limited. The α heat quantity ratio of the support layer 24 may be the same as that of the base material 10 or the skin layer 22, or may be different from both.

[0040] The β heat quantity ratio of the support layer 24 is not particularly limited. The β heat quantity ratio of the support layer 24 may be the same as that of the base material 10 or the skin layer 22, or may be different from both.

[0041] The β heat quantity ratio of the support layer 24 is preferably smaller than that of the skin layer 22. That is, the β heat quantity ratio of the skin layer 22 is preferably larger than that of the support layer 24. The β heat quantity ratio of the skin layer 22 is preferably 5 points or more, more preferably 10 points or more, larger than that of the support layer 24. When the difference between the β heat quantity ratio of the skin layer 22 and the β heat quantity ratio of the support layer 24 is above the above, the elastic modulus can be increased and the rigidity can be further increased. The upper limit value of the difference between the β heat quantity ratio of the skin layer 22 and the β heat quantity ratio of the base material 10 is substantially 20 points.

[0042] The sealant material 20 may contain a light-shielding inorganic substance. By containing a light-shielding inorganic substance, the sealant material 20 can reduce the light transmittance of the film 1 for packaging and enhance the light-shielding property. The light-shielding inorganic substance may be contained in the support layer 24 or may be contained in the skin layer 22. The light-shielding inorganic substance is an inorganic substance that shields ultraviolet rays and visible light by scattering or reflection. Examples of the light-shielding inorganic substance include titanium dioxide, zinc oxide, calcium carbonate, talc (magnesium hydrosilicate), etc. Titanium dioxide is preferable as the light-shielding inorganic substance because it has a high refractive index and is more likely to shield ultraviolet rays and visible light.

[0043] The content of the light-shielding inorganic substance is more than 5% by mass and less than 50% by mass, preferably 10% by mass or more and 45% by mass or less, more preferably 15% by mass or more and 40% by mass or less, based on the total mass of the sealant material 20. When the content of the light-shielding inorganic substance exceeds the above lower limit value, the light-shielding property of the film 1 for packaging can be further enhanced. When the content of the light-shielding inorganic substance is less than the above upper limit value, peeling of the inorganic vapor deposition layer can be suppressed when the sealant material 20 has a 0 inorganic vapor deposition layer.

[0044] When the light-shielding inorganic substance is in powder form, the average primary particle diameter of the light-shielding inorganic substance is preferably, for example, 100 to 500 nm, more preferably 200 to 400 nm. When the average primary particle diameter of the light-shielding inorganic substance is at least the above lower limit value, the light-shielding property of the film 1 for packaging can be further enhanced. When the average primary particle diameter of the light-shielding inorganic substance is at most the above upper limit value, the impact resistance of the film 1 for packaging can be further enhanced. In this specification, the average primary particle diameter can be determined, for example, by analyzing an image taken using a transmission electron microscope.

[0045] The thickness T20 of the sealant material 20 is determined in consideration of the material, configuration, etc., and is preferably, for example, 20 to 100 μm, more preferably 30 to 80 μm. When the thickness T20 of the sealant material 20 is at least the above lower limit value, the oxygen barrier property, water vapor barrier property, and light-shielding property of the film 1 for packaging can be further enhanced. When the thickness T20 of the sealant material 20 is at most the above upper limit value, the flexibility of the film 1 for packaging is enhanced, making it easier to handle. The thickness T20 of the sealant material 20 can be measured in the same manner as the thickness T10 of the base material 10.

[0046] The thickness T22 of the skin layer 22 can be appropriately determined according to the use of the film 1 for packaging, and is preferably, for example, 2 to 30 μm, more preferably 2 to 20 μm, still more preferably 5 to 20 μm. When the thickness T22 is at least the above lower limit value, the seal stability can be further enhanced. When the thickness T22 is at most the above upper limit value, the seal stability can be further enhanced. The thickness T22 of the skin layer 22 can be measured in the same manner as the thickness T12 of the inorganic vapor deposition layer 12.

[0047] ≪Adhesive layer≫ The adhesive layer 30 is located between the base material 10 and the sealant material 20. The adhesive layer 30 is not particularly limited as long as it can bond the base material 10 and the sealant material 20. As the adhesive layer 30, a cured product of an isocyanate-based adhesive containing a polyester polyol having a carbon-carbon double bond and a compound having an isocyanate group is preferred. When the subsequent layer 30 has a carbon-carbon double bond in the components of the isocyanate-based adhesive, it has oxygen absorbency. In addition, when the isocyanate-based adhesive of the present embodiment contains an oxygen absorbent, the adhesive layer 30 can absorb oxygen and suppress oxygen from permeating through the packaging film 1. For this reason, the packaging film 1 can have higher oxygen barrier properties by having the adhesive layer 30.

[0048] The isocyanate-based adhesive of the present embodiment has a polyester polyol having a carbon-carbon double bond as the main agent and a compound having an isocyanate group as the curing agent. That is, the isocyanate-based adhesive of the present embodiment is a urethane-based adhesive containing a main agent and a curing agent. Examples of the polyester polyol include unsaturated polyesters composed of a polyvalent carboxylic acid component containing at least one aromatic dicarboxylic acid or its anhydride. Phthalic anhydride is preferable as the aromatic dicarboxylic acid or its anhydride. Examples of the curing agent of the isocyanate-based adhesive of the present embodiment include toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate), and the like. From the viewpoint of low environmental impact and excellent adhesive strength, IPDI is preferable as the curing agent.

[0049] Examples of the oxygen absorbent include one or more selected from conjugated diene polymer cyclized products and transition metal salts. Examples of the conjugated diene polymer cyclized product include polyterpenes such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-phenyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, or poly(α-pinene), poly(β-pinene), poly(dipentene), etc. obtained by cyclizing these compounds. As the conjugated diene polymer cyclized product, a polyisoprene cyclized product is preferable.

[0050] Examples of the transition metal salt include salts of transition metal elements and organic acids. Examples of the transition metal element include iron, nickel, copper, manganese, cobalt, rhodium, titanium, chromium, vanadium, ruthenium, etc. As the transition metal element, iron, nickel, copper, manganese, cobalt are preferable, manganese and cobalt are more preferable, and cobalt is even more preferable. Examples of the organic acid include acetic acid, stearic acid, dimethyldithiocarbamic acid, palmitic acid, 2-ethylhexanoic acid, neodecanoic acid, linoleic acid, toluic acid, oleic acid, resin acid, capric acid, naphthenic acid, etc. As the organic acid, stearic acid, palmitic acid, neodecanoic acid, linoleic acid, oleic acid are preferable, and neodecanoic acid and oleic acid are preferable. As the transition metal salt, cobalt neodecanoate and cobalt oleate are preferable. These oxygen absorbers may be used alone or in combination of two or more.

[0051] The content of the oxygen absorber is 1% by mass or more based on the total mass of the isocyanate-based adhesive, preferably 1 to 10% by mass, more preferably 3 to 8% by mass, and even more preferably 4 to 6% by mass. When the content of the oxygen absorber is at least the above lower limit value, the oxygen barrier property of the film 1 for packaging can be further enhanced. When the content of the oxygen absorber is at most the above upper limit value, the adhesiveness between the printing layer 40 and the sealant material 20 can be further enhanced. In addition, when the content of the oxygen absorber is at most the above upper limit value, it is advantageous in terms of cost.

[0052] In the isocyanate-based adhesive, the mass ratio of the main agent to the curing agent is preferably 100:103 to 100:150, more preferably 100:103 to 100:130, and even more preferably 100:105 to 100:125. When the mass ratio of the main agent to the curing agent is at least the above lower limit value, the adhesiveness between the base material 10 and the sealant material 20 can be further enhanced. When the mass ratio of the main agent to the curing agent is at most the above upper limit value, the water vapor barrier property of the film 1 for packaging can be further enhanced.

[0053] In the adhesive layer 30, the content of unreacted isocyanate groups is preferably 3 to 30 mol%, more preferably 3 to 20 mol%, and even more preferably 5 to 10 mol% with respect to the content of the generated urethane groups. When the content of unreacted isocyanate groups is at least the above lower limit value, since the unreacted isocyanate groups absorb water vapor, the water vapor barrier property of the film 1 for packaging can be further enhanced. When the content of unreacted isocyanate groups is at most the above upper limit value, the adhesiveness between the base material 10 and the sealant material 20 can be further enhanced, and it is also advantageous in terms of cost. The content of unreacted isocyanate groups can be measured by a Fourier transform infrared spectrophotometer (FTIR). Specifically, the film 1 for packaging is irradiated with infrared light, and transmission mapping measurement is performed using an infrared microscope. By analyzing the spectrum obtained by the transmission mapping measurement in the range of the wavelength of infrared light of 2,500 to 25,000 nm (2.5 to 25 μm), and obtaining the ratio of the height of the peak of urethane groups to the height of the peak of isocyanate groups in the adhesive layer 30, the content of unreacted isocyanate groups with respect to the content of urethane groups can be obtained.

[0054] The isocyanate-based adhesive may be a one-component type adhesive or a two-component type adhesive. From the viewpoint of fast curing speed and excellent adhesive strength, a two-component type adhesive of a main agent and a curing agent is preferred as the isocyanate-based adhesive. The isocyanate-based adhesive may contain a main agent, a curing agent, and other components other than the oxygen absorber. Examples of the other components include additives and organic solvents generally used in adhesives. The content of the other components is preferably 0 to 20% by mass based on the total mass of the isocyanate-based adhesive.

[0055] The thickness T30 of the adhesive layer 30 is preferably, for example, 1.0 to 5.0 μm, more preferably 1.5 to 4.0 μm. When the thickness T30 of the adhesive layer 30 is equal to or greater than the above lower limit value, the adhesiveness between the base material 10 and the sealant material 20 can be further enhanced. When the thickness T30 of the adhesive layer 30 is equal to or less than the above upper limit value, cohesive failure of the adhesive layer 30 can be suppressed. The thickness T30 of the adhesive layer 30 can be measured in the same manner as the thickness T12 of the inorganic vapor deposition layer 12.

[0056] [Method for manufacturing a film for a package] The method for manufacturing a film for a package of the present invention includes a step of laminating a base material and a sealant material (lamination step), a first heat treatment step of subjecting the base material to a first heat treatment, and a second heat treatment step of subjecting the sealant material to a second heat treatment. Hereinafter, a method for manufacturing a film for a package of the present invention will be described with reference to one embodiment. The method for manufacturing the film 1 for a package of the present embodiment includes a base material manufacturing step, a sealant material manufacturing step, a lamination step, a first heat treatment step, and a second heat treatment step.

[0057] ≪Base material manufacturing step≫ The base material manufacturing step is a step of obtaining a biaxially stretched polypropylene film. The method for manufacturing the biaxially stretched polypropylene film is selected from conventionally known methods such as the inflation method, the T-die method, and the coextrusion method according to the material and configuration of the base material 10. In the present invention, instead of the base material manufacturing step, a pre-prepared base material may be used.

[0058] In the present embodiment, the base material manufacturing step includes a vapor deposition operation. In the vapor deposition operation, an inorganic vapor deposition layer 12 is provided on the biaxially stretched polypropylene film. The method for providing the inorganic vapor deposition layer 12 on the biaxially stretched polypropylene film is not particularly limited, and a conventionally known vacuum vapor deposition method can be applied. In the vapor deposition operation, the degree of vacuum in the vapor deposition chamber is preferably, for example, 0.1 to 0.5 Pa. In the vapor deposition operation, the conveyance speed of the unstretched polypropylene film is preferably, for example, 100 to 400 m / min.

[0059] ≪Sealant Material Manufacturing Process≫ The sealant material manufacturing process is a process of obtaining a polypropylene film having a first layer of polypropylene (the layer that will become the support layer 24) and a second layer of polypropylene (the layer that will become the skin layer 22). The sealant material manufacturing process melts and kneads a resin containing polypropylene and, if necessary, optional components (for example, light-shielding inorganic substances), and forms this into a film. As the method for forming the film, a conventionally known method such as the inflation method, the T-die method, or the coextrusion method is selected according to the material, configuration, etc. In the sealant material manufacturing process, the first layer and the second layer may be manufactured separately and then laminated, or the second layer may be extruded onto the first layer, or the first layer and the second layer may be coextruded. In the present invention, instead of the sealant material manufacturing process, a pre-prepared sealant material may be used.

[0060] When the sealant material 20 has an inorganic vapor deposition layer, the sealant material manufacturing process may include a vapor deposition operation. By having a vapor deposition operation in the sealant material manufacturing process, it will have an inorganic vapor deposition layer.

[0061] ≪Lamination Process≫ In the laminating process, the base material 10 and the sealing material 20 are joined to obtain a laminate in which the base material 10, the adhesive layer 30, and the sealing material 20 are laminated in this order. The method of joining the base material 10 and the sealing material 20 in the laminating process is selected from conventionally known methods such as the dry lamination method. In the dry lamination method, for example, an adhesive is applied to the inorganic vapor deposition layer 12 of the base material 10 to be laminated, the base material 10 and the sealing material 20 are laminated via the adhesive, and each layer is pressure-bonded and dried to obtain a laminate. The obtained laminate is wound up in a roll shape, for example. Note that although an adhesive is used in the laminating process of the present embodiment, the present invention is not limited to this, and it is not always necessary to use an adhesive as long as the base material 10 and the sealing material 20 can be joined.

[0062] ≪First heat treatment step≫ In the first heat treatment step, the base material 10 is subjected to a first heat treatment so that the α heat quantity ratio in the base material 10 is 60% or more. Examples of the method of performing the first heat treatment include a method of heating the laminate obtained in the laminating process with a heating device. Examples of the heating device used in the first heat treatment step include a drying oven. In the first heat treatment step, the α heat quantity ratio in the sealing material 20 may be 60% or more, or may be 60% or less.

[0063] The heating temperature in the first heat treatment is preferably, for example, 55 to 110°C, more preferably 60 to 90°C. When the heating temperature of the first heat treatment is equal to or higher than the above lower limit value, the α heat quantity ratio of the base material 10 can be increased more. When the heating temperature of the first heat treatment is equal to or lower than the above upper limit value, damage due to heating of each layer is reduced, and the oxygen barrier property and water vapor barrier property of the film 1 for packaging can be enhanced more.

[0064] The time of the first heat treatment (heating time) is preferably, for example, 1 to 10 seconds, more preferably 3 to 6 seconds. When the heating time is equal to or longer than the above lower limit value, the α heat quantity ratio of the base material 10 can be further increased. When the heating time is equal to or shorter than the above upper limit value, β crystals can be more easily formed in the skin layer 22 in the second heat treatment step described later.

[0065] <<Second Heat Treatment Step>> In the second heat treatment step, the skin layer 22 of the laminate that has been subjected to the first heat treatment is subjected to a second heat treatment to form the skin layer 22 on the sealant material 20. By performing the second heat treatment, the β heat quantity ratio of the skin layer 22 is increased. Examples of the method of performing the second heat treatment include a method of heating the laminate with a heating device. Examples of the heating device used in the second heat treatment step include a constant temperature chamber and the like.

[0066] The heating temperature in the second heat treatment is preferably, for example, 30 to 55°C, more preferably 35 to 50°C. When the heating temperature of the second heat treatment is equal to or higher than the above lower limit value, the β heat quantity ratio of the surface of the sealant material 20 and its vicinity can be further increased. When the heating temperature of the second heat treatment is equal to or lower than the above upper limit value, damage due to heating of each layer is reduced, and the oxygen barrier property and water vapor barrier property of the packaging film 1 can be further enhanced.

[0067] The time of the second heat treatment (heating time) is preferably, for example, 24 to 72 hours, more preferably 18 to 48 hours. When the heating time is equal to or longer than the above lower limit value, the β heat quantity ratio near the surface of the sealant material 20 can be further increased. When the heating time is equal to or shorter than the above upper limit value, the α heat quantity ratio can be increased.

[0068] <<Printing Step>> The method for manufacturing the packaging film of the present embodiment may include a printing step. By having the printing step, a printing layer can be formed on the packaging film 1. The printing method is not particularly limited, and various printing methods such as offset printing, gravure printing, flexographic printing, screen printing, and inkjet printing can be adopted. The printing target may be the base material 10 or the sealant material 20.

[0069] In the above-described embodiment, the first heat treatment step and the second heat treatment step are performed after the lamination step, but the present invention is not limited thereto. For example, the base material may be subjected to the first heat treatment, the sealant material may be subjected to the second heat treatment, and then the base material and the sealant material may be laminated.

[0070] ≪Package≫ The package of the present embodiment is obtained by forming a bag from the film 1 for the package of the present embodiment. Examples of the package include a bag formed by heat-sealing the skin layers 22 of the sealant material 20 of the film 1 for the package. Examples of the form of the package include a gusseted bag, a three-side sealed bag, a four-side sealed bag, a gusset bag, a stand-up bag, and a bag with a chuck of these. Further, for example, as the package, there is provided a container body having an opening and a lid body made of the film 1 for the package, and the skin layer 22 is brought into contact with the peripheral edge of the opening of the container body, and the film 1 for the package is heat-sealed to the container body. In this case, from the viewpoint of easy recyclability, polypropylene is preferable as the material of the container body.

[0071] As described above, since the materials of the base material and the sealant material of the film for the package of the present embodiment are both polypropylene, recycling is easy. Since the film for the package of the present embodiment has an inorganic vapor deposition layer, it is excellent in oxygen barrier property, water vapor barrier property, and light shielding property, and since it is in the category of a single material, recycling is easy. Since the base material of the film for the package of the present embodiment is a biaxially stretched film, it has the rigidity required for the package. Therefore, a package excellent in packaging suitability can be obtained without excessively increasing the thickness of the film for the package. That is, according to the present embodiment, it is possible to reduce the volume of the film for the package while obtaining the necessary rigidity. In addition, since the film for packaging bodies of the present embodiment has a base material layer with a specific α heat quantity ratio, it is excellent in rigidity. Since the film for packaging bodies of the present embodiment has a skin layer with a specific β heat quantity ratio, the seal strength can be increased and the impact resistance strength can be enhanced.

[0072] Hereinafter, the present invention will be described by showing examples, but the present invention is not limited to the following examples. The materials and test conditions used in this example are as follows.

[0073] [Materials Used] ≪Base Material≫ ·OPP1-1: A film in which an aluminum (Al2O3) vapor deposition layer is formed on a biaxially stretched polypropylene film. ML OP102 (trade name), manufactured by Mitsui Chemicals Toagosei Co., Ltd., total thickness = 30 μm, thickness of aluminum vapor deposition layer = 0.06 μm (600 Å). α heat quantity ratio = 60%, β heat quantity ratio = 40%. ·OPP1-2: A film in which an aluminum (Al2O3) vapor deposition layer is formed on a biaxially stretched polypropylene film. Barrier Plus ZOP (trade name), manufactured by Daicel Chemical Industries, Ltd., total thickness = 20 μm, thickness of aluminum vapor deposition layer = 0.06 μm (600 Å). α heat quantity ratio = 60%, β heat quantity ratio = 40%. ·OPP1-3: A biaxially stretched polypropylene film. Pyren OT P2161 (trade name), manufactured by Toyobo Co., Ltd., total thickness = 30 μm. α heat quantity ratio = 65%, β heat quantity ratio = 35%. ·OPP1-4: A film in which an aluminum (Al2O3) vapor deposition layer is formed on a biaxially stretched polypropylene film. Sun Mirror OP-M (trade name), manufactured by Nisshō Co., Ltd., total thickness = 30 μm, thickness of aluminum vapor deposition layer = 0.04 μm (400 Å). α heat quantity ratio = 60%, β heat quantity ratio = 40%.

[0074] ≪Sealant Material≫ ·OPP2-1: A biaxially stretched polypropylene film. FOH (trade name), manufactured by Futamura Chemical Co., Ltd., total thickness = 30 μm. α heat quantity ratio = 60%, β heat quantity ratio = 40% (among them, β' heat quantity ratio = 15%). · OPP2-2: A film with an aluminum (Al2O3) vapor deposition layer formed on a 2-axis stretched polypropylene film. FG-LTH (trade name), manufactured by Futamura Chemical Co., Ltd., total thickness = 35 μm. α heat ratio = 65%, β heat ratio = 35% (including β' heat ratio = 15%). · CPP2-1: Unstretched polypropylene film. Trephan 3951 (trade name), manufactured by Toray Industries, Inc., total thickness = 30 μm. α heat ratio = 55%, β heat ratio = 45% (including β' heat ratio = 15%).

[0075] ≪Adhesive layer≫ <Main agent> · Saturated polyester: Manufactured by Nippon Gohsei Co., Ltd. · Phthalic anhydride: Manufactured by Junsei Chemical Co., Ltd. <Hardening agent> · IPDI: Isophorone diisocyanate, Takenate (registered trademark), manufactured by Mitsui Chemicals, Inc. · TDI: Toluene diisocyanate, Takenate (registered trademark), manufactured by Mitsui Chemicals, Inc.

[0076] [Experimental Examples 1 to 12] According to the specifications and manufacturing conditions in Table 1A and Table 1B, a film for a package similar to the film 1 for a package in Fig. 1 was manufactured. The sealant material and the base material were joined with a urethane-based adhesive to obtain a laminate. The obtained laminate was heat-treated under the conditions of the first heat treatment in the table. Then, the laminate was heat-treated under the conditions of the second heat treatment in the table to obtain the film for a package of each example. Regarding the obtained film for a package, the α heat ratio and β heat ratio of the base material were measured, and the seal strength, impact resistance, oxygen barrier property (O2TR), water vapor barrier property (WVTR), and rigidity were evaluated, and the results are shown in the table. The layer composition in the table is described in the order of "base material / sealant material", and "μ" represents the unit of thickness "μm". In addition, the type of sealant material (OPP or CPP) indicates the support layer. In the table, "-" indicates that the configuration is not included. In the table, the α heat ratio and β heat ratio are described as the ratio of the α heat ratio to the β heat ratio (α / β ratio).

[0077] [Evaluation method] <Evaluation of water vapor barrier property (WVTR)> For the base materials of each example, in accordance with the test method described in the humidity sensor method of JIS K7129:2008, the water vapor transmission rate was measured under Test Condition 1 described in Table A.1, and the water vapor barrier property was evaluated based on the following evaluation criteria. The results are shown in Table 1A and Table 1B. 《Evaluation criteria》 ◎: Water vapor transmission rate 2.0 g / (m 2 ·day) or less. ○: Water vapor transmission rate exceeds 2.0 g / (m 2 ·day) and is 4.0 g / (m 2 ·day) or less. ×: Water vapor transmission rate exceeds 4.0 g / (m 2 ·day).

[0078] <Evaluation of oxygen barrier property (O2TR)> For the film for packaging obtained in each example, the oxygen permeability was measured in accordance with the test method for oxygen gas permeability by the electrolytic sensor method described in Annex A of JIS K7126-2:2006, and the oxygen barrier property was evaluated based on the following evaluation criteria. The results are shown in Table 1B. 《Evaluation criteria》 ◎: Oxygen permeability 0.5 mL / (m 2 ·day) or less. ○: Oxygen permeability exceeds 0.5 mL / (m 2 ·day) and is 3.5 mL / (m 2 ·day) or less. ×: Oxygen permeability exceeds 3.5 mL / (m 2 ·day).

[0079] <Evaluation of impact resistance> The film for packaging obtained in each example was heat-sealed (sealing temperature: 180 °C, sealing time: 1 second, sealing pressure: 3.5 kg / cm 2, with a seal width of 10 mm, a three-sided sealed bag (flat bag) of 130 mm × 170 mm was produced. 180 mL of water was filled into this flat bag, and the opening was heat-sealed under the same conditions as above to obtain a sample for evaluation. This evaluation sample was dropped vertically from a height of 1.2 m onto the concrete surface, and this operation was repeated 3 times (drop strength test). Among the 10 evaluation samples, the number of samples in which leakage of the contents was observed (number of broken bags) was counted, and the impact resistance was evaluated based on the following evaluation criteria. The results are shown in Table 1B. 《Evaluation Criteria》 ◎: The number of broken bags is 0. ○: The number of broken bags is 1 or 2. ×: The number of broken bags is 3 or more.

[0080] <Seal Strength> Samples were cut out from the three-sided seal made in "<Evaluation of Impact Resistance>", and the seal strength was measured under the following conditions in accordance with the "Heat Seal Strength Test" of JIS Z1707. The seal strength in the table is the average value of the measurement results of 5 test pieces.

[0081] ≪Measurement Method≫ Test piece: 15 mm wide. Measurement environment: 23 °C, 50% RH. Measuring instrument: Strograph E-L (manufactured by Toyo Seiki Seisakusho Co., Ltd.). Grip interval: 50 mm. Tensile speed: 300 mm / min. 《Evaluation Criteria》 ◎: The seal strength is 15 N / 15 mm or more. ○: The seal strength is more than 10 N / 15 mm and less than 15 N / 15 mm. ×: The seal strength is 10 N / 15 mm or less.

[0082]

Table 1A

[0083]

Table 1B

[0084] As shown in Tables 1A to 1B, in Examples 1 to 6 to which the present invention was applied, all of the seal strength, impact resistance, rigidity, oxygen barrier property, and water vapor barrier property were “◎” or “○”. In Comparative Example 1 and Comparative Example 2 where the β calorific value ratio of the skin layer was 1%, the seal strength and impact resistance were “×”. In Comparative Example 3 where the sealing material was an unstretched polypropylene film, the rigidity was “×”. From the above results, it was confirmed that by applying the present invention, it is excellent in various functions and can be easily recycled.

Explanation of Reference Numerals

[0085] 1 Film for packaging 10 Base material 12 Inorganic vapor deposition layer 20 Sealing material 22 Skin layer 24 Support layer 30 Adhesive layer

Claims

1. A sealing material and a biaxially stretched polypropylene base material located on one surface of the sealing material, The sealing material has a support layer of stretched polypropylene and a skin layer of polypropylene, The skin layer forms the other surface of the sealing material, In the base material, the heat quantity ratio of the endothermic peak derived from α-crystals is 60% or more with respect to the total heat quantity of the endothermic peak of the base material, In the skin layer, the heat quantity ratio of the endothermic peak derived from β-crystals is 2.0% or more with respect to the total heat quantity of the endothermic peak of the skin layer, A film for a package, wherein at least one of the sealing material and the base material has an inorganic vapor deposition layer.

2. The film for a package according to Claim 1, having a thickness of 30 to 120 μm.

3. The thickness of the sealing material is 20 to 100 μm, The film for a package according to Claim 1, wherein the thickness of the skin layer is 2 to 30 μm.

4. A package formed by bagging the film for a package according to any one of Claims 1 to 3.

5. A method for manufacturing a film for a package, having a sealing material and a biaxially stretched polypropylene base material located on one surface of the sealing material, the sealing material having a support layer of biaxially stretched polypropylene and a skin layer of polypropylene, the skin layer forming the other surface of the sealing material, and at least one of the sealing material and the base material having an inorganic vapor deposition layer, the method comprising: A lamination step of laminating the sealing material and the base material; A first heat treatment step of subjecting the base material to a first heat treatment so that the heat quantity ratio of the endothermic peak derived from α-crystals in the base material is 60% or more with respect to the total heat quantity of the endothermic peak of the base material; A second heat treatment step of subjecting the skin layer to a second heat treatment so that the heat quantity ratio of the endothermic peak derived from β-crystals in the skin layer is 2.0% or more with respect to the total heat quantity of the endothermic peak of the skin layer.

6. The method for manufacturing a film for a package according to Claim 5, wherein the second heat treatment step is performed after the lamination step.

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