Laminate, sealant film, packaging bag, package, and wet heat treatment package

Abstract

To provide a laminate, a sealant film, a packaging bag, a package, and a wet heat treatment package which have low-temperature heat-sealability, but still have excellent resistance to sealing surface fusion even after wet heat treatment.SOLUTION: The laminate at least comprises a base material layer and a sealant layer. The surface softening temperature measured by local thermal analysis of a sealing surface of the sealant layer is from 110°C to 140°C inclusive. The sealant layer has a fusion strength of 2.0 N / 15 mm or less when the sealant layer is heat-sealed with a sealant layer identical to the sealant layer at 121°C and 0.05 MPa for 30 seconds. The base material layer and the sealant layer contains a polypropylene-based resin.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a laminate, a sealant film, a packaging bag, a package, and a moist heat-treated package. [Background technology]

[0002] In recent years, there has been an increasing need for environmentally friendly, sustainable packaging materials, and progress has been made in the development of packaging materials (monomaterial packaging materials) that are highly recyclable and consist of laminates of layers containing the same material.

[0003] Because mono-material packaging has inner and outer layers made of the same material, the outer layer has poorer heat resistance than packaging composed of a laminate with inner and outer layers made of different resins (multi-material packaging).For this reason, mono-material packaging requires high heat resistance for the outer layer and a low melting point, i.e., low-temperature heat sealability, for the inner layer.

[0004] As an example of such a monomaterial packaging material, Patent Document 1 discloses a composite film having two layers, a base layer and a heat-seal layer, with the base layer and the heat-seal layer made of a propylene random copolymer and a high-density polyethylene, respectively. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2022 / 234761 Summary of the Invention [Problem to be solved by the invention]

[0006] However, even though the composite film described in Patent Document 1 has heat sealing properties at low temperatures (less than 155° C.), when a packaging bag obtained using the composite film is subjected to a moist heat treatment such as a retort treatment at a high temperature of, for example, about 120° C., the inner surfaces (sealed surfaces) of the packaging bag fuse together, resulting in a seal surface fusion property. On the other hand, improving the seal surface fusion resistance sometimes makes it impossible to achieve low-temperature heat sealing properties. The present disclosure has been made in consideration of the above circumstances, and aims to provide a laminate, a sealant film, a packaging bag, a package, and a package that is subjected to moist heat treatment, which have low-temperature heat sealing properties and also have excellent resistance to sealing surface fusion even when subjected to moist heat treatment. [Means for solving the problem]

[0007] One aspect of the present disclosure provides a laminate comprising at least a base layer and a sealant layer, wherein the sealant layer has a surface softening temperature of 110°C or higher and 140°C or lower as determined by local thermal analysis of the sealing surface thereof, and the sealant layer has a fusion strength of 2.0 N / 15 mm or lower when heat-sealed to the same sealant layer under conditions of 121°C, 0.05 MPa, and 30 seconds, and wherein the base layer and the sealant layer contain a polypropylene-based resin. The laminate has low-temperature heat-sealing properties and excellent resistance to sealing surface fusion even after moist heat treatment. Specifically, when the laminate is used to produce a packaging bag, if the sealing surfaces of the laminate are placed face to face and heat-sealed, heat sealing can be performed at a lower temperature than when the surface softening temperature of the sealing surfaces measured by local thermal analysis exceeds 140°C. Furthermore, even when the laminate is used to produce a packaging bag by heat-sealing the sealing surfaces and then moist heat treatment is performed on the package containing the contents, the laminate can suppress fusion of the sealing surfaces compared to when the fusion strength exceeds 2.0 N / 15 mm.

[0008] The laminate is preferably subjected to a heating and pressure treatment under conditions of 0.33 MPa, 130°C, and 30 minutes, and then the surface softening temperature of the sealing surface determined by local thermal analysis is preferably 140°C or higher and 150°C or lower. In this case, the laminate has low-temperature heat sealing properties and also has excellent resistance to sealing surface fusion even when subjected to moist heat treatment. Therefore, even when a packaging bag is made using the laminate by heat-sealing the sealing surfaces together and the packaging bag containing the contents is subjected to moist heat treatment, the laminate can sufficiently prevent the sealing surfaces from fusion-sealing together.

[0009] In the above laminate, when the sealant layer is heat-sealed to the same sealant layer under conditions of 0.05 MPa and 30 seconds, it is preferable that T2 - T1 be 10.0 N / 15 mm or less, where T1 (N / 15 mm) is the fusion strength when the heat sealing temperature is 121°C and T2 (N / 15 mm) is the fusion strength when the heat sealing temperature is 128°C. In this case, the laminate has resistance to sealing surface fusion even when subjected to moist heat treatment at 125° C. or higher. Therefore, even when a packaging bag is made using the laminate by heat-sealing the sealing surfaces together and the packaging bag containing the contents is subjected to moist heat treatment at 125° C. or higher, the laminate can prevent the sealing surfaces from fusing together.

[0010] In the total reflection infrared absorption spectrum of the above seal surface, -1 More than 983cm -1 The peak intensity of the absorption peak appearing in the first region below is P1, 700 cm -1 More than 750cm -1 When the peak intensity of one absorption peak appearing in the second region below is P2, and when two or more absorption peaks exist in the second region, the peak intensity of the absorption peak on the higher wavenumber side of the two absorption peaks with the largest peak intensities in the second region is P3, and the peak intensity of the absorption peak on the lower wavenumber side is P4, it is preferable that the peak intensity ratio P2 / P1 or P3 / P1 is 0.15 or less, or P4 / P3 is 1.5 or less. In this case, the laminate has better resistance to sealing surface adhesion even after undergoing moist heat treatment, and therefore, even when the laminate is used to prepare a packaging bag by heat-sealing the sealing surfaces together and the packaging bag containing the contents is subjected to moist heat treatment, the laminate can effectively prevent the occurrence of sealing surface adhesion.

[0011] When the sealant layer is heat-sealed to the same sealant layer under conditions of 135°C, 0.05 MPa and 30 seconds, it preferably has a fusion strength of 10.0 N / 15 mm or less. In this case, the laminate has resistance to sealing surface fusion even when subjected to moist heat treatment at 130° C. or higher. Therefore, even when a packaging bag is made using the laminate by heat-sealing the sealing surfaces together and the packaging bag containing the contents is subjected to moist heat treatment at 130° C. or higher, the laminate can prevent the sealing surfaces from fusioning together.

[0012] The laminate preferably further includes a gas barrier layer. In this case, the gas barrier property of the laminate is further improved, and therefore, when a packaging bag is made using the laminate and contents are placed in the packaging bag to produce a package, the laminate can effectively suppress deterioration of the contents due to gases such as oxygen.

[0013] Another aspect of the present disclosure provides a packaging bag obtained by using the above-described laminate and heat-sealing the sealing surfaces together. This packaging bag has low-temperature heat-sealing properties and can prevent fusion between the sealed surfaces even when subjected to a moist heat treatment. The packaging bag may be used for purposes requiring heat treatment at 80°C or higher.

[0014] Another aspect of the present disclosure provides a sealant film containing a polypropylene-based resin, wherein the sealant film has a surface softening temperature of 110°C or higher and 140°C or lower as determined by local thermal analysis of the sealing surface thereof, and when the sealant film is heat-sealed to another sealant film under conditions of 121°C, 0.05 MPa, and 30 seconds, the sealant film has a fusion strength of 2.0 N / 15 mm or lower. Since this sealant film is heat-sealed at low temperatures, when a packaging bag is produced using a laminate formed together with a base layer containing a polypropylene-based resin, the laminate can be heat-sealed at low temperatures by arranging the sealing surfaces of the laminate to face each other and heat-sealing them. Furthermore, when a packaging bag is produced using a laminate formed together with a base layer containing a polypropylene-based resin and the sealing surfaces are heat-sealed together, this sealant film can suppress fusion of the sealing surfaces even when subjected to a moist heat treatment.

[0015] Yet another aspect of the present disclosure provides a packaging body comprising a packaging bag and contents contained within the packaging bag, the packaging bag being formed using the above-described laminate, and the sealing surface constituting the inner surface of the packaging bag. This packaging body can prevent the sealing surfaces of the packaging bags from fusing together even when a moist heat treatment is performed. Therefore, the packaging body can be easily opened. Furthermore, after the packaging body is opened, the contents can be easily removed and sufficiently discharged. As a result, the packaging bag remaining after the contents are discharged can be highly recyclable. Furthermore, with the above packaging body, the laminate has low-temperature heat-sealing properties, so that when the packaging bag is formed, thermal degradation of layers in the laminate other than the sealant layer can be suppressed. Therefore, deterioration in the quality of the contents of the packaging body can be suppressed.

[0016] Yet another aspect of the present disclosure provides a moist heat treated package comprising a packaging bag and contents to be placed in the packaging bag, the packaging bag being formed using a laminate, the laminate comprising at least a base layer and a sealant layer, the surface softening temperature of the sealing surface of the sealant layer measured by local thermal analysis being 140°C or higher and 150°C or lower, the base layer and the sealant layer containing a polypropylene-based resin, and the sealing surface constituting the inner surface of the packaging bag. According to this moist heat-treated package, the laminate can prevent the sealing surfaces of the packaging bags from fusing together due to the moist heat treatment, thereby preventing the sealing surfaces of the moist heat-treated packaging bags from fusing together. This makes it easy to open the moist heat-treated package. Furthermore, after opening the moist heat-treated package, the contents can be easily removed and fully discharged. As a result, the packaging bag remaining after the contents are discharged can be highly recyclable. [Effects of the Invention]

[0017] According to the present disclosure, there are provided a laminate, a sealant film, a packaging bag, a package, and a package that can be subjected to moist heat treatment, which have low-temperature heat sealing properties and excellent resistance to sealing surface fusion even when subjected to moist heat treatment. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a cross-sectional view schematically illustrating one embodiment of a laminate according to the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view schematically illustrating one embodiment of the packaging body of the present disclosure. [Figure 3] FIG. 3 is a plan view showing a sealed body used to measure the fusion strength of the sealant layer. [Figure 4] FIG. 4 is a cross-sectional view schematically showing one embodiment of a moist heat treatment package according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present disclosure will be described. Note that the same components are denoted by the same reference numerals, and duplicate explanations will be omitted. Furthermore, the dimensional ratios in the drawings are not limited to those shown in the drawings.

[0020] [Laminate] First, an embodiment of the laminate of the present disclosure will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view schematically showing one embodiment of the laminate of the present disclosure. 1, the laminate 100 includes at least a base layer 10 and a sealant layer 30. The surface of the sealant layer 30 opposite to the base layer 10 is a sealing surface 30a. The base layer 10 and the sealant layer 30 contain a polypropylene-based resin. In the sealant layer 30, the surface softening temperature of the sealing surface 30a is 110°C or higher and 140°C or lower, as determined by local thermal analysis. Furthermore, the sealant layer 30 has a fusion strength of 2.0 N / 15 mm or less when heat-sealed to the same sealant layer under conditions of 121° C., 0.05 MPa, and 30 seconds.

[0021] The laminate 100 may further include an intermediate layer 20 between the substrate layer 10 and the sealant layer 30. The laminate 100 may further include a printed layer, if necessary.

[0022] The laminate 100 has low-temperature heat-sealing properties and also excellent resistance to sealing surface fusion, even when subjected to moist heat treatment. Specifically, when a packaging bag is made using the laminate 100, by heat-sealing the sealing surfaces 30a of the laminate 100 facing each other, heat sealing can be performed at a lower temperature than when the surface softening temperature of the sealing surfaces 30a measured by local thermal analysis exceeds 140°C. Furthermore, even when a packaging bag is made using the laminate 100 by heat-sealing the sealing surfaces 30a, and the packaging bag containing contents is then subjected to moist heat treatment, the laminate 100 can suppress fusion between the sealing surfaces 30a compared to when the fusion strength exceeds 2.0 N / 15 mm.

[0023] The laminate 100, the base layer 10, the sealant layer 30, the intermediate layer 20 and the printed layer will be described in detail below.

[0024] (Laminate) The content of the polypropylene-based resin in the laminate 100 is not particularly limited, but is preferably 72% by mass or more. In this case, it is possible to improve the recyclability of the laminate 100. From the viewpoint of further improving the recyclability, the content of the polypropylene-based resin in the laminate 100 is more preferably 92% by mass or more, and even more preferably 95% by mass or more.

[0025] (base material layer) The base layer 10 is a layer that supports the sealant layer 30 and contains a polypropylene-based resin.

[0026] The polypropylene-based resin contained in the base layer 10 is composed of a resin containing propylene as a constituent unit. Examples of polypropylene-based resins include homopolypropylene, propylene copolymers obtained by copolymerizing propylene with an α-olefin such as ethylene or butene, and ethylene-propylene rubber. These can be used alone or in combination of two or more. Examples of the propylene copolymer include a propylene-ethylene random copolymer, a propylene-ethylene block copolymer, and a propylene-ethylene terpolymer. The polypropylene resin may be a block polypropylene, which is a mixture of homopolypropylene and ethylene propylene rubber.

[0027] The base layer 10 may be a non-stretched film or a stretched film. The stretched film may be a uniaxially stretched film or a biaxially stretched film. The base layer 10 may also be a laminate containing a stretched film and a non-stretched film. The base layer 10 preferably comprises a biaxially stretched film, which can improve the mechanical strength and dimensional stability of the laminate 100.

[0028] The surface of the base layer 10 on the sealant layer 30 side may be subjected to various pretreatments such as corona treatment, plasma treatment, ozone treatment, and flame treatment, or may be provided with a coating layer such as an easy-adhesion layer. The base layer 10 may contain a resin other than a polypropylene-based resin, such as a polyolefin-based resin, for example, a polyethylene-based resin. The base layer 10 may contain at least one additive selected from the group consisting of a filler, an antistatic agent, a plasticizer, a lubricant, and an antioxidant, as needed.

[0029] (sealant layer) The sealant layer 30 is a layer that provides heat-sealing properties to the laminate 100 and contains a polypropylene-based resin. The polypropylene-based resin contains a resin containing propylene as a constituent unit. Examples of polypropylene-based resins include homopolypropylene, propylene copolymers obtained by copolymerizing propylene with an α-olefin such as ethylene or butene, and ethylene-propylene rubber. These can be used alone or in combination of two or more. Examples of the propylene copolymer include a propylene-ethylene random copolymer, a propylene-ethylene block copolymer, and a propylene-ethylene terpolymer. The polypropylene resin may be a block polypropylene, which is a mixture of homopolypropylene and ethylene propylene rubber.

[0030] The sealant layer 30 may be a non-stretched film or a stretched film, but is preferably a non-stretched film from the viewpoint of lowering the heat sealing temperature and improving the sealability by heat sealing.

[0031] The sealant layer 30 may be composed of a single layer or a laminate of multiple layers.

[0032] The thickness of the sealant layer 30 may be, for example, 20 μm or more, 60 μm or more, or 100 μm or more. The thickness of the sealant layer 30 may be 150 μm or less, 100 μm or less, or 60 μm or less, but is preferably 100 μm or less. When the thickness of the sealant layer 30 is 100 μm or less, the amount of heat required for heat sealing can be easily reduced, and heat damage to the base layer 10 and intermediate layer 20 in the laminate 100 can be easily reduced.

[0033] (1) Surface softening temperature of the sealing surface (1-1)Surface softening temperature B As described above, the surface softening temperature of the sealing surface 30a determined by local thermal analysis (hereinafter also referred to as "surface softening temperature B") is 110°C or higher and 140°C or lower. When the surface softening temperature B is 110°C or higher, there is an advantage in that the sealing surface has better resistance to fusion even after wet heat treatment, compared to when the surface softening temperature B is lower than 110°C. Furthermore, when the surface softening temperature B is 140°C or lower, heat sealing can be performed at a lower temperature, compared to when the surface softening temperature B is higher than 140°C. The surface softening temperature B may be 115°C or higher, 120°C or higher, or 125°C or higher. The surface softening temperature B may be 138°C or less, 135°C or less, 133°C or less, or 130°C or less.

[0034] For example, when the polypropylene-based resin used in the sealant layer 30 contains homopolypropylene or block polypropylene, the sealant layer 30 has a high surface softening temperature B. On the other hand, when the polypropylene-based resin contains random polypropylene or elastomer, the sealant layer 30 has a low surface softening temperature B. Therefore, by appropriately adjusting the type and blending ratio of the polypropylene-based resin, the surface softening temperature B of the sealant layer 30 can be adjusted to a desired value.

[0035] The surface softening temperature is the temperature at which a material such as a resin exhibits softening behavior. In this embodiment, the surface softening temperature A is measured by performing local thermal analysis (LTA) on the sealing surface 30a of the sealant layer 30 using an atomic force microscope (AFM). Specifically, the surface softening temperature A is calculated as follows. First, the sealant layer 30 is prepared. At this time, the sealant layer 30 itself may be prepared, or a laminate obtained by attaching another film such as the base layer 10 to the sealant layer 30 may be prepared. To measure the surface softening temperature A, the sealant layer 30 is heated by applying a voltage to a cantilever equipped with a heater. Local thermal analysis (LTA) involves measuring the shape of the surface (sealing surface 30a) of the sealant layer 30, applying a constant force (contact pressure) with a cantilever to a predetermined location on the surface of the sealant layer 30, and then heating while maintaining the contact pressure. The surface softening temperature is calculated as the temperature at which the cantilever height (Z displacement) changes due to the change in hardness of the sealing surface 30a before and after heating. The change in cantilever height refers to the vertical rise of the cantilever due to thermal expansion of the sealing surface 30a and the vertical fall of the cantilever due to softening of the sealing surface 30a. By converting the voltage applied to the cantilever heater when such a change in cantilever height occurs into the surface softening temperature, the softening temperature can be determined locally in the nanoscale region and near the surface.

[0036] To convert the voltage applied to the cantilever heater into a softening temperature, a calibration curve of applied voltage and temperature is created. Four polymeric materials with melting points differing by at least 50°C are used as calibration samples. These polymeric materials include materials with melting points above the surface softening temperature of the sealant layer 30 and materials with melting points below the surface softening temperature. The melting points (melting peak temperatures) of the calibration samples are measured in advance using a differential scanning calorimeter (DSC), and the melting points are used as the surface softening temperatures of the calibration samples. Local thermal analysis is performed at different measurement positions on each calibration sample, and a calibration curve is created by approximating the average applied voltage at the obtained softening points and the softening temperatures of the calibration samples (melting points measured by DSC) with a cubic function using the least squares method. This calibration curve is used as the calibration curve.

[0037] Using this applied voltage vs. temperature calibration curve, the temperature corresponding to the applied voltage at the softening point is determined, and this temperature is taken as the surface softening temperature. In this way, the surface softening temperature is calculated.

[0038] (1-2)Surface softening temperature A In the sealant layer 30, it is preferable that the surface softening temperature (hereinafter also referred to as "surface softening temperature A") of the seal surface 30a determined by local thermal analysis after pressure and heat treatment under conditions of 0.33 MPa, 130°C, and 30 minutes is 140°C or higher and 150°C or lower. When the surface softening temperature A is 150°C or lower, the laminate 100 can have low-temperature heat sealing properties. Furthermore, when the surface softening temperature A is 140°C or higher, the laminate 100 can have better resistance to sealing surface fusion even when subjected to moist heat treatment. Therefore, even when a packaging bag is made using the laminate 100 by heat-sealing the sealing surfaces 30a together, and the packaging bag containing contents is then subjected to moist heat treatment, the laminate 100 can sufficiently prevent the sealing surfaces 30a from fusing together. The surface softening temperature A may be 143°C or higher, 145°C or higher, or 146°C or higher. The surface softening temperature A may be 149°C or less or 148°C or less. The surface softening temperature A can be measured in the same manner as the surface softening temperature B.

[0039] The above-mentioned pressurization and heat treatment is a treatment that simulates the effect on the sealant layer 30 of heat in the moist heat treatment.

[0040] (2) Fusion strength The sealant layer 30 has a fusion strength T1 of 2.0 N / 15 mm or less when heat-sealed to the same sealant layer under conditions of 121°C, 0.05 MPa, and 30 seconds. Because the fusion strength T1 is 2.0 N / 15 mm or less, the laminate 100 can suppress fusion between the seal surfaces 30 a even when a packaging bag is made using the laminate 100 by heat-sealing the seal surfaces 30 a of the sealant layers 30 together, and the packaging bag containing contents is then subjected to a moist heat treatment. The fusion strength T1 may be 1.8 N / 15 mm or less, or may be 1.6 N / 15 mm or less. The fusion strength T1 may be 0 N / 15 mm or greater than 0 N / 15 mm. The fusion strength may be 0.1 N / 15 mm or greater, 0.3 N / 15 mm or greater, or 0.5 N / 15 mm or greater. The sealant layer identical to the sealant layer 30 refers to a sealant layer having the same constituent material and thickness as the sealant layer 30 .

[0041] When the sealant layer 30 is heat-sealed to the same sealant layer under conditions of 128°C, 0.05 MPa, and 30 seconds, the fusion strength is defined as T2 (N / 15 mm). While T2 - T1 is not particularly limited, it is preferably 10.0 N / 15 mm or less, more preferably 8 N / 15 mm or less, and particularly preferably 6 N / 15 mm or less. When T2 - T1 is 10.0 N / 15 mm or less, the laminate 100 has resistance to sealing surface fusion even after moist heat treatment at 125°C or higher. Therefore, even when a packaging bag is made using the laminate 100 by heat-sealing the sealing surfaces 30a together, and the packaging bag containing the contents is then subjected to moist heat treatment at 125°C or higher, the laminate 100 can prevent the sealing surfaces 30a from fusing together. T2-T1 may be 0 N / 15 mm or greater. If T2-T1 is greater than 0 N / 15 mm, it may be 0.1 N / 15 mm or greater, 0.5 N / 15 mm or greater, or 1.0 N / 15 mm or greater.

[0042] When sealant layer 30 is heat-sealed to the same sealant layer under conditions of 135° C., 0.05 MPa, and 30 seconds, sealant layer 30 preferably has a fusion strength T3 of 10.0 N / 15 mm or less. In this case, the laminate 100 has resistance to sealing surface fusion even when subjected to moist heat treatment at 130° C. or higher. Therefore, even when a packaging bag is made using the laminate 100 by heat-sealing the sealing surfaces 30a together, and the packaging bag containing contents is subjected to moist heat treatment at 130° C. or higher, the laminate 100 can prevent the sealing surfaces 30a from fusing together. The fusion strength T3 may be 8.0 N / 15 mm or less, or 5.0 N / 15 mm or less. The fusion strength T3 may be 1.0 N / 15 mm or more, or 2.0 N / 15 mm or more.

[0043] The fusion strength is measured by a T-peel test. The method for measuring the fusion strength will be described below with reference to Fig. 3. Fig. 3 is a plan view showing a sealed body used to measure the fusion strength of the sealant layer. First, two films each made of a sealant layer are prepared for measurement. As shown in FIG. 3, each film is prepared so that it is 60 mm long in the machine direction (MD) during film formation and 120 mm long in the direction perpendicular to the MD during film formation (TD). The two films are then overlapped, and a 10 mm-wide region from the edge 600a in the TD is heat-sealed by applying a pressure of 0.05 MPa for 30 seconds while heating at a predetermined heat-sealing temperature (121°C, 128°C, or 135°C), forming the heat-sealed region 610 indicated by the diagonal lines. In this way, the sealed body 600 is obtained. The heat-sealed region 610 is 10 mm long in the MD and 120 mm long in the TD. Next, a portion 620 indicated by the broken line in FIG. 3 is cut out from the seal body 600 to obtain a test piece having a width of 15 mm in the TD direction and a length of 60 mm in the MD direction. Finally, a T-peel test is performed using the test piece. The T-peel test is performed in accordance with JIS K 6854-3. The tensile strength when the heat-sealed portion of the test piece is peeled off is taken as the fusion strength of the heat-sealed portion under the heat-sealing conditions. In this way, the fusion strength is measured.

[0044] (3) Peak intensity ratio in total reflection infrared absorption spectrum When the total reflection infrared absorption spectrum of the sealing surface 30a was measured, the sealant layer 30 contained a polypropylene-based resin (for example, a random polypropylene copolymer) and exhibited a peak at 963 cm ―1 More than 983cm ―1 In the first region below, one absorption peak due to the methyl group of the polypropylene resin appears. In addition, when the polypropylene resin contained in the sealant layer 30 contains a methylene group, ―1 More than 750cm ―1 An absorption peak due to the methylene group appears in the second region below. When the content of polyethylene-based resin in sealant layer 30 increases or the type of polypropylene-based resin becomes, for example, block polypropylene, this absorption peak splits into two absorption peaks due to a change in crystallinity. Here, if the peak intensity of the absorption peak appearing in the first region is P1, if there is one absorption peak appearing in the second region, the peak intensity of that absorption peak is P2, and if two or more absorption peaks appear in the second region, of the two largest absorption peaks in the second region, the peak intensity of the absorption peak on the higher wavenumber side is P3 and the peak intensity of the absorption peak on the lower wavenumber side is P4, it is preferable that the peak intensity ratio P2 / P1 is 0.15 or less, P3 / P1 is 0.15 or less, or P4 / P3 is 1.5 or less. In this case, the laminate 100 has better resistance to sealing surface fusion even after a moist heat treatment. Therefore, even when a packaging bag is made using the laminate 100 by heat-sealing the sealing surfaces 30a together, and the packaging bag contains contents, and the moist heat treatment is then performed on the packaging, the laminate 100 can effectively prevent the sealing surfaces 30a from fusing together.

[0045] P2 / P1 or P3 / P1 is preferably 0.15 or less, more preferably 0.13 or less, and in this case, fusion between the sealing surfaces 30a can be more effectively suppressed even when a wet heat treatment is performed at a high temperature, compared to when P2 / P1 or P3 / P1 exceeds 0.15. P2 / P1 or P3 / P1 may be 0.04 or more, or may be 0.06 or more.

[0046] It is preferable that P4 / P3 is 1.2 or less. P4 / P3 may be 0.5 or more, or may be 1.0 or more.

[0047] The total reflection infrared absorption spectrum is an infrared absorption spectrum obtained by irradiating the sealing surface 30a of the sealant layer 30 with infrared light through a prism and measuring the light totally reflected at the interface between the sealant layer 30 and the prism. The peak intensity of each absorption peak refers to the difference between the intensity at the maximum point of the absorption peak and the intensity at the baseline in the total reflection infrared absorption spectrum measured as described above.

[0048] When the sealant layer 30 contains a large amount of homopolypropylene, or when the sealant layer 30 contains a propylene copolymer and the propylene copolymer contains a large amount of propylene, the proportion of methyl groups in the sealant layer 30 increases, and the value of P1 tends to increase. On the other hand, when the sealant layer 30 contains a large amount of a material with low crystallinity and methylene groups, such as polyethylene or random polypropylene containing ethylene as a structural unit, the absorption peak of the second region is less likely to split. In this case, the value of P2 tends to increase as the proportion of ethylene in the polyethylene or propylene copolymer in the sealant layer 30 increases. Furthermore, when the sealant layer 30 contains a large amount of a material with high crystallinity and methylene groups, such as block polypropylene, the absorption peak of the second region tends to split. In this case, the higher the proportion of block polypropylene in the sealant layer 30, the larger the values of P3 and P4, and especially the value of P4. Therefore, by appropriately adjusting the type of polypropylene-based resin and the blending ratio of polyethylene-based resin contained in the sealant layer 30, the peak intensity ratios P1 / P2, P3 / P2, and P3 / P4 can be adjusted to the desired values.

[0049] (middle class) The intermediate layer 20 may be, for example, a gas barrier film. By providing the laminate 100 with a gas barrier film as the intermediate layer 20, when a packaging bag is produced using the laminate 100 and contents are placed in the packaging bag to produce a package, deterioration of the contents due to gases such as oxygen can be effectively suppressed. The gas barrier film includes a gas barrier layer. The gas barrier layer may include a vapor-deposited layer made of an inorganic compound.

[0050] The inorganic compounds that make up the deposition layer include SiO X and AlO X Examples include: As a gas barrier layer, for example, SiO X When using a gas barrier layer, the gas barrier layer becomes transparent, so that the contents can be visually confirmed from the outside of the packaging bag. The deposition layer is SiO X and AlO X The thickness of the deposited layer may be, for example, 15 to 30 nm. The gas barrier film only needs to include a gas barrier layer, and may be composed of only a gas barrier layer, or may be composed of a resin film (plastic film), an anchor coat layer, and a gas barrier layer in this order. Here, the gas barrier layer may be provided on either the base layer 10 side or the sealant layer 30 side of the resin film.

[0051] The gas barrier layer has gas barrier properties even when it is composed of only a vapor deposition layer, but it is preferably composed of a composite layer formed by laminating a coating layer on top of the vapor deposition layer.

[0052] When the gas barrier layer is constructed as a composite layer, a reaction layer between the vapor-deposited layer and the coating layer occurs at the interface between the two layers, or the coating layer fills or reinforces defects or micropores such as pinholes, cracks, and grain boundaries that occur in the vapor-deposited layer, forming a dense structure. Therefore, a gas barrier layer constructed as a composite layer combining a coating layer and a vapor-deposited layer achieves higher gas barrier properties, moisture resistance, and water resistance, and has flexibility that allows it to withstand deformation due to external forces, making the laminate 100 suitable for use as a packaging material.

[0053] The coating layer can be formed, for example, by a coating method in which a coating agent is applied onto the vapor-deposited layer and then dried by heating. The coating agent can be based on an aqueous solution or a water / alcohol mixed aqueous solution containing a water-soluble polymer and at least one of alkoxides, their hydrolysates, and tin chloride. The coating agent may further contain a silane monomer. In this case, the adhesion between the coating layer and the vapor-deposited layer can be improved.

[0054] The anchor coat layer can be formed using a curable compound (resin) such as urethane acrylate, for example, by coating a paint in which the curable compound is dissolved in a solvent using a coating method that applies a printing technique such as gravure coating, or a commonly known coating method.

[0055] The resin film may contain any resin. The resin is not particularly limited, but is preferably a polypropylene-based resin. When the resin film contains a polypropylene-based resin, the laminate 100 has even higher recyclability. The resin film may be a non-stretched film or a stretched film, but is preferably a stretched film from the viewpoint of heat resistance and dimensional stability. The stretched film may be a uniaxially stretched film or a biaxially stretched film. When the stretched film is a biaxially stretched film, the strength and transparency of the laminate 100 are further improved. The thickness of the resin film may be appropriately set depending on the intended use of the laminate 100, and may be 10 μm or more, or 15 μm or more. The thickness of the resin film may be 40 μm or less, or 25 μm or less. The intermediate layer 20 may be an adhesive layer instead of a gas barrier layer, or may further include an adhesive layer.

[0056] (Printing layer) The laminate 100 may include a printed layer, as previously mentioned. The printed layer can be provided on at least one surface of the base layer 10 or on at least one surface of the intermediate layer 20 . The print layer is provided at a position visible from the outside of the laminate 100 for the purposes of displaying information about the contents, identifying the contents, improving concealment, or improving the design of the packaging bag. The printing ink is not particularly limited, and is appropriately selected from known printing inks taking into consideration the printability on other layers in the laminate 100, design such as color tone, adhesion, and safety as a food container. The printing method is not particularly limited and may be appropriately selected from known printing methods. Examples of printing methods that can be used include gravure printing, offset printing, gravure offset printing, flexographic printing, and inkjet printing. Among these, gravure printing is preferably used from the viewpoints of productivity and high definition of the image.

[0057] [Sealant film] Next, an embodiment of the sealant film of the present disclosure will be described. The sealant film of the present disclosure is composed of the above-mentioned sealant layer 30. That is, the sealant film contains a polypropylene-based resin, has a sealing surface 30a, and has a surface softening temperature of the sealing surface 30a measured by local thermal analysis of 110°C or higher and 140°C or lower, and has a fusion strength of 2.0 N / 15 mm or lower when heat-sealed under conditions of 121°C, 0.05 MPa, and 30 seconds.

[0058] Because this sealant film is heat-sealed at low temperatures, when a packaging bag is produced using a laminate formed with a base layer containing a polypropylene-based resin, the laminate can be heat-sealed at low temperatures by arranging the sealing surfaces of the laminate to face each other and heat-sealing them. Furthermore, when a packaging bag is produced using a laminate formed with a base layer containing a polypropylene-based resin and the sealing surfaces are heat-sealed together, this sealant film can prevent fusion of the sealing surfaces 30a even when subjected to a moist heat treatment.

[0059] [Packaging] Next, an embodiment of the packaging body of the present disclosure will be described with reference to Fig. 2. Fig. 2 is a cross-sectional view that schematically shows one embodiment of the packaging body of the present disclosure. 2, the packaging body 500 includes a packaging bag 400 and contents C contained in the packaging bag 400. The packaging bag 400 is formed using a laminate 100, and the sealed surface 30a forms the inner surface of the packaging bag 400. Specifically, the packaging bag 400 is formed by overlapping two laminates 100 with their sealed surfaces 30a facing each other and heat-sealing the peripheral edges of the sealed surfaces 30a. Therefore, the packaging bag 400 includes a main body portion 401 in which the contents C are contained and a sealed portion 402 that surrounds the main body portion 401.

[0060] The packaging body 500 can prevent the sealing surfaces 30a of the packaging bag from fusing together due to the moist heat treatment. Therefore, when opening the packaging body 500 by pulling the opposing sealing surfaces 30a of the packaging bag 400 apart from each other, the packaging body 500 can be easily opened. Furthermore, by cutting out a part of the sealing portion 402 to form an opening, after opening the packaging body 500, the contents C can be easily removed through the opening and the contents C can be sufficiently discharged. As a result, the packaging bag 400 remaining after the contents C have been discharged can be highly recyclable. Furthermore, according to the packaging body 500, since the laminate 100 has low-temperature heat sealing properties, it is possible to suppress thermal deterioration of layers (base material layer 10 or intermediate layer 20) other than the sealant layer 30 in the laminate 100 when the packaging bag 400 is formed. Therefore, deterioration in the quality of the contents C in the packaging body 500 can be suppressed.

[0061] (Contents) The contents C are not particularly limited, but examples of the contents C include food, medicine, etc. When the contents C are food, the contents C can be easily removed from the package 500 after opening the package 500, and the contents C can be sufficiently discharged. Therefore, the package 500 can also reduce food waste.

[0062] (packaging bag) In this embodiment, the packaging bag 400 includes a main body portion 401 in which the contents C are accommodated, and a seal portion 402 that surrounds the main body portion 401. That is, the packaging bag 400 is configured as a four-sided pouch. The two laminates 100 constituting the packaging bag 400 may be made of different materials and may have different thicknesses, shapes, etc. The packaging bag 400 is not particularly limited to a four-sided pouch and can be appropriately selected depending on the intended use of the packaging bag. The packaging bag 400 may be, for example, a three-sided pouch, a pillow bag, a standing pouch, a gusset bag, a bag with a spout, or the like. The packaging bag 400 may be made up of three or more laminates 100. In this case, the plurality of laminates 100 constituting the packaging bag 400 may be made of different materials and may have different thicknesses, shapes, etc.

[0063] The packaging bag 400 may be used for applications requiring heat treatment at 80° C. or higher. Examples of heat treatment include moist heat treatment such as retort treatment and boiling treatment.

[0064] [Heat-moisture treated packaging] Next, an embodiment of a moist heat treatment package according to the present disclosure will be described with reference to Fig. 4. Fig. 4 is a cross-sectional view schematically showing one embodiment of a moist heat treatment package according to the present disclosure. 4, the moist heat treatment package 700 includes a packaging bag 900 and contents C accommodated in the packaging bag 900. The packaging bag 900 is formed using a laminate 800, and the sealed surface 830a forms the inner surface of the packaging bag 900. Specifically, the packaging bag 900 is formed by overlapping two laminates 800 with their sealed surfaces 830a facing each other, heat-sealing the peripheral edges of the sealed surfaces 830a, and then performing a moist heat treatment. Examples of moist heat treatments include retort treatment and boiling treatment. Retort treatment is a pressurized and heated treatment under conditions of, for example, 0.33 MPa, 130°C, and 30 minutes, while boiling treatment is a heated treatment under conditions of, for example, 80°C, and 45 minutes. The laminate 800 includes a base layer 10 and a sealant layer 830, the surface softening temperature of a sealing surface 830a of the sealant layer 830 being 140°C or higher and 150°C or lower as determined by local thermal analysis, the sealant layer 830 containing a polypropylene-based resin, and the sealing surface 830a forming the inner surface of the packaging bag 900. The sealing surface 830a is the surface of the sealant layer 830 opposite the base material layer 10. According to this moist heat treatment packaging body 700, the laminate 800 can prevent the sealing surfaces 830a of the packaging bags 900 from fusing together due to the moist heat treatment, and therefore, the sealing surfaces 830a of the packaging bags 900 that have been retorted are prevented from fusing together. This makes it possible to easily open the moist heat treatment packaging body 700. Furthermore, after opening the moist heat treatment packaging body 700, the contents C can be easily removed and the contents C can be sufficiently discharged. As a result, the packaging bag 900 that remains after the contents C have been discharged can be highly recyclable.

[0065] The surface softening temperature may be 143°C or higher, 145°C or higher, or 146°C or higher. The surface softening temperature may also be 149°C or lower, or 148°C or lower. The surface softening temperature can be measured in the same manner as for the surface softening temperature A.

[0066] The two laminates 800 constituting the packaging bag 900 may be made of different materials and may have different thicknesses, shapes, etc. The packaging bag 900 is not particularly limited to a four-sided pouch, and can be appropriately selected depending on the intended use of the packaging bag. The packaging bag 900 may be, for example, a three-sided pouch, a pillow bag, a standing pouch, a gusset bag, a bag with a spout, or the like. The packaging bag 900 may be configured with three or more laminates 800. In this case, the multiple laminates 800 that make up the packaging bag 900 may be configured with different materials and may have different thicknesses, shapes, etc. [Example]

[0067] Examples of the present disclosure will be specifically described below, but the present disclosure is not limited to the following examples.

[0068] Example 1 First, a biaxially oriented polypropylene film (OPP2) (manufactured by Futamura Chemical Co., Ltd., trade name "FOR") having a thickness of 20 μm was prepared as a resin film. Next, a vapor-deposited film was formed on one surface of the resin film using a vacuum vapor deposition device, thereby obtaining a gas barrier film.

[0069] Next, a polyurethane adhesive was applied to the surface of the gas barrier film on the vapor deposition layer side, and a 20 μm-thick biaxially oriented polypropylene film (OPP1) (manufactured by Futamura Chemical Co., Ltd., product name "FOR") was used as a base layer. The polyurethane adhesive used here was "Takelac A626 / Takenate A50" manufactured by Mitsui Chemicals, Inc.

[0070] Next, the polyurethane adhesive was applied to the surface of the gas barrier film opposite the vapor deposition layer, and a 60 μm thick unstretched polypropylene film (CPP film) was attached to the surface via the adhesive to form a sealant layer, thus producing a laminate (substrate layer / vapor deposition layer / resin film / sealant layer).

[0071] For the above sealant layer, the surface softening temperature B (before pressurization and heat treatment), surface softening temperature A (after pressurization and heat treatment), fusion strength T1 at 121°C, fusion strength T2 at 128°C, fusion strength T3 and T2-T1 at 135°C, and total reflection infrared absorption spectrum were calculated or measured as described below. The surface softening temperatures B and A, fusion strengths T1, T2, T3, T2-T1, and peak intensity ratios P2 / P1, P3 / P1, and P4 / P3 were as shown in Table 1.

[0072] (Examples 2 to 9 and Comparative Examples 2 to 3) A laminate was prepared in the same manner as in Example 1, except that a CPP film having the thickness, surface softening temperatures B and A, fusion strengths T1, T2, T3, and T2-T1, and peak intensity ratios P2 / P1, P3 / P1, and P4 / P3 shown in Table 1 was used as the sealant layer.

[0073] (Comparative Example 1) A laminate was prepared in the same manner as in Example 1, except that a CPP film (trade name "Torayfan (registered trademark) NO ZK207", manufactured by Toray Advanced Film Co., Ltd.) having the thickness, surface softening temperatures B and A, fusion strengths T1, T2, T3, T2-T1, and peak intensity ratios P2 / P1, P3 / P1, and P4 / P3 shown in Table 1 was used as the sealant layer.

[0074] (1)Surface softening temperature The surface softening temperatures B and A of the sealing surface of the sealant layer were calculated as follows.

[0075] (1-1)Surface softening temperature B First, we prepared a surface softening temperature measurement device including an atomic force microscope (AFM) MFP-3D-SA (trade name) manufactured by Oxford Instruments, a local thermal analysis option Ztherm System (trade name), and a cantilever AN2-200 (trade name) manufactured by Anasys Instruments with a spring constant of 0.5 to 3.5 N / m. On the other hand, a sealant film was prepared as a sealant layer to be used in the production of a laminate. Then, using the above-mentioned surface softening temperature measuring device, the surface softening temperature and shape of the seal surface of the sealant film were measured. The measurement mode was AC mode (tapping mode) for measuring the shape of the seal surface, and contact mode for measuring the surface softening temperature. The surface softening temperature measurement was performed on a 10 μm × 10 μm area including the center of the seal surface (the intersection of the diagonal lines).

[0076] At this time, the cantilever contact pressure (change in cantilever deflection) was set to a deflection voltage change of 0.2 V, the voltage application rate (heating rate) was 0.5 V / s, and the maximum applied voltage was 5.5 V. The seal surface was heated after detrend correction. After the seal surface expanded and the cantilever position rose, the seal surface was further heated to soften it, and the measurement was terminated when the cantilever position had dropped 10 nm. If the cantilever's vertical height (Z displacement) had not dropped 50 nm from the change point and the maximum applied voltage was reached, the maximum applied voltage during detrend correction and measurement was increased by 0.5 V and the measurement was performed again.

[0077] The voltage applied at the point where the vertical height (Z displacement) of the cantilever was maximum was taken as the voltage applied at the softening point, and the voltage value was read.

[0078] To calculate the surface softening temperature of the sealant layer, a calibration curve was created to match the measurement conditions for the sealant layer. The calibration samples used were the following four polymer materials whose melting points (melting peak temperatures) had been measured in advance using a differential scanning calorimeter (DSC), and samples were prepared in an environment below their glass transition temperatures. Polycaprolactone pellets (melting point: 60°C) Low-density polyethylene pellets (melting point: 112°C) Polypropylene pellets (melting point: 166°C) Biaxially stretched polyethylene terephthalate film (melting point: 255°C) The measurement conditions were a voltage application rate (heating rate) of 0.5 V / s, and a maximum applied voltage of 3.5 V for polycaprolactone, 5 V for low-density polyethylene, 6 V for polypropylene, and 7.8 V for polyethylene terephthalate. The cantilever contact pressure (change in cantilever deflection) was set at a deflection voltage change of 0.2 V. After detrend correction, the seal surface was heated and the applied voltage at the softening point was measured. The softening point voltage was measured 10 times by changing the measurement position of the calibration sample. A calibration curve was created by approximating the average applied voltage at the softening point and the melting point (melting peak temperature) measured by DSC using a cubic function using the least squares method. This calibration curve was used as the calibration curve.

[0079] Using a calibration curve of applied voltage and temperature, the temperature corresponding to the applied voltage at the softening point of the seal surface was determined, and this temperature was taken as the surface softening temperature B. The results are shown in Table 1.

[0080] (1-2)Surface softening temperature A First, two sealant films each measuring 120 mm (MD direction) x 120 mm (TD direction) were prepared from the CPP film used as the sealant layer in the examples and comparative examples. Next, the sealing surfaces of the two sealant films were placed facing each other, and three sides were heat-sealed to produce a packaging bag with an opening. Next, 150 mL of water was filled into the packaging bag through the opening, and the opening was heat-sealed to close the opening, thereby producing a package. Next, the prepared package was heated by spraying 130°C water on it for 30 minutes under a pressure of 0.33 MPa, and then cooled by spraying 40°C water on it for 10 minutes under a pressure of 0.33 MPa. Finally, the sealed portion of the package was cut off, the water was drained, and the sealed surface was dried. In this way, a sealant film that had been subjected to heat and pressure treatment was prepared. Then, for the sealant film after this heating and pressure treatment, the surface softening temperature A was calculated in the same manner as for the surface softening temperature B. The results are shown in Table 1.

[0081] (2) Fusion strength The fusion strength was measured by a T-peel test. Specifically, two films each consisting of a sealant layer were prepared for measurement. Each film measured 60 mm (MD) × 120 mm (TD). The two films were then overlapped, and a 10 mm-wide region from the edge 600a in the TD direction was heat-sealed by applying a pressure of 0.05 MPa for 30 seconds while heating at a predetermined heat-sealing temperature (121°C, 128°C, or 135°C). This resulted in a 10 mm (MD) × 120 mm (TD) heat-sealed region, as shown by the diagonal lines in Figure 3. A sealed body was thus obtained. Next, a portion 620 indicated by the broken line in FIG. 3 was cut out from the seal body to obtain a test piece measuring 15 mm (TD direction) x 60 mm (MD direction). Finally, a T-peel test was performed using the test specimen. The T-peel test was performed in accordance with JIS K 6854-3 under the following test conditions. The tensile strength when the heat-sealed portion of the test specimen was peeled was taken as the fusion strength of the heat-sealed portion under the heat-sealing conditions. The fusion strength was measured in this manner. The results are shown in Table 1. (Test conditions) Chuck distance: 15mm Pulling speed: 300mm / min Tensile direction: MD

[0082] (3) Peak intensity ratios P2 / P1, P3 / P1, P4 / P3 The peak intensity ratios P2 / P1, P3 / P1, and P4 / P3 were calculated as follows. First, the total reflection infrared absorption spectrum of the seal surface of the sealant layer was measured under the following measurement conditions using a total reflection infrared absorption spectrometer (product name "Spectrum Spotlight 400 / Frontier", manufactured by PerkinElmer). (Measurement conditions) Prism material: Diamond Measurement wavenumber range: 400 to 4000 cm -1 Number of times accumulated: 16 In the measured total reflection infrared absorption spectrum, 1130±5cm -1 and 680c±5cm -1 The line connecting the minimum points in was determined as the baseline. Next, in the total reflection infrared absorption spectrum, the difference between the intensity at the maximum point of the absorption peak and the intensity at the baseline was defined as the peak intensity of the absorption peak, and peak intensities P1 to P4 were calculated. Finally, the peak intensity ratios P2 / P1, P3 / P1, and P4 / P3 were calculated based on the calculated peak intensities P1 to P4. The results are shown in Table 1.

[0083] <Sealing surface adhesion resistance> Test pieces 1 and 2 were prepared from the laminates produced in the examples and comparative examples under two different heating conditions as described below, and these test pieces 1 and 2 were used to determine and evaluate the sealing surface fusion resistance as described below. (1) Test piece 1 (heating conditions: 125°C, 30 min) First, two laminate pieces each having a length of 120 mm in the MD direction and the TD direction were cut out from the laminates produced in the examples and comparative examples. Next, the two cut-out pieces of the laminate were overlapped with the sealed surfaces facing each other, and with the sealed surfaces in close contact with each other, the four sides of the laminate were heat-sealed with an impulse sealer to produce a fused body. The fused specimen was heated by spraying hot water at 125°C for 30 minutes under pressure of 0.21 MPa, and then cooled by spraying water at 40°C for 10 minutes under pressure of 0.21 MPa. The fused specimen was then left to stand at room temperature for one day. After standing, the heat-sealed portions on all four sides of the fused specimen were cut out, and the remaining central portion of the fused specimen was prepared as test piece 1.

[0084] (2) Test piece 2 (heating conditions: 130°C, 30 min) Test piece 2 was prepared under the same heating conditions as in heating condition 1, except that the fused body was heated by spraying hot water at 130°C for 30 minutes.

[0085] (3) Judgment and evaluation of sealing surface adhesion resistance For the test pieces 1 and 2 prepared as described above, the two laminate pieces were each pinched by hand and pulled apart, and the resistance felt during peeling was evaluated according to the following five-level evaluation criteria. The evaluation results are shown in Table 1. (Judgment criteria) 1: No resistance at all when peeling 2: Almost no resistance when peeling 3: There is a slight resistance when peeling off 4: There is a strong resistance when peeling off 5: The test piece is fused and there is a significant resistance (when peeled off, deformation or changes in the appearance of the sealing surface (such as cohesive peeling) occur) The test pieces that were judged as "1" and "2" were evaluated as "◎", the test piece that was judged as "3" was evaluated as "〇", the test piece that was judged as "4" was evaluated as "△", and the test piece that was judged as "5" was evaluated as "×". The results are shown in Table 1.

[0086] <Low temperature heat sealability> The low-temperature heat sealability was evaluated based on the seal initiation temperature of the sealant layer used in the examples and comparative examples. The seal initiation temperature of the sealant layer was measured as follows. First, as shown in Figure 3, two sealant layers measuring 120 mm (TD) x 60 mm (MD) were prepared, and these two sealant layers were heated at T°C while being pressurized at 0.2 MPa for 1 second with a seal width of 10 mm to prepare a heat-sealed body. At this time, the heat-sealed bodies were prepared by setting T to a heating temperature between 130°C and 170°C, which differed in increments of 2°C. Then, test pieces measuring 60 mm (TD direction) x 15 mm (MD direction) were prepared from these heat-sealed bodies. A T-peel test was performed on each of the multiple test pieces prepared as described above. The T-peel test was performed in accordance with JIS K 6854-3. Specifically, the T-peel test was performed in the MD direction under conditions of a chuck distance of 15 mm and a pulling speed of 300 mm / min. The lowest temperature at which the peel strength was 10 N / 15 mm or more was determined as the sealing initiation temperature of the sealant layer.

[0087] The low-temperature heat sealability of the sealant layer was evaluated based on the following criteria, and the results are shown in Table 1. (Evaluation criteria) 〇: Sealing start temperature is less than 155℃ ×: Sealing start temperature is 155℃ or higher

[0088] [Table 1]

[0089] From the results shown in Table 1, in Examples 1 to 9, the sealing start temperature was less than 155°C, and the sealing surface fusion resistance was evaluated as 1 to 4 under the heating conditions of "125°C, 30 min" and "130°C, 30 min," confirming that the laminates had low-temperature heat sealability but did not fuse together between the sealed surfaces. In contrast, in Comparative Example 1, the sealing start temperature was 156°C, which was 155°C or higher. Furthermore, in Comparative Examples 2 and 3, the sealing surface fusion resistance was evaluated as 5 under the heating conditions of "125°C, 30 min" and "130°C, 30 min," confirming that fuses did occur between the sealed surfaces.

[0090] From the above, it was confirmed that the laminate of the present disclosure has low-temperature heat sealability and also has excellent resistance to sealing surface fusion even when subjected to moist heat treatment.

[0091] The outline of this disclosure is as follows. [1] A laminate comprising at least a base layer and a sealant layer, wherein the surface softening temperature of the seal surface of the sealant layer measured by local thermal analysis is 110°C or higher and 140°C or lower, and wherein the sealant layer has a fusion strength of 2.0 N / 15 mm or lower when heat-sealed to the same sealant layer under conditions of 121°C, 0.05 MPa, and 30 seconds, and wherein the base layer and the sealant layer contain a polypropylene-based resin. [2] The laminate according to [1], wherein the surface softening temperature of the sealing surface measured by local thermal analysis after the laminate is subjected to pressure and heat treatment under conditions of 0.33 MPa, 130°C, and 30 minutes is 140°C or higher and 150°C or lower. [3] The laminate according to [1] or [2], wherein when the sealant layer is heat-sealed to the same sealant layer under conditions of 0.05 MPa and 30 seconds, T2 - T1 is 10.0 N / 15 mm or less, where T1 (N / 15 mm) is the fusion strength when the heat sealing temperature is 121°C and T2 (N / 15 mm) is the fusion strength when the heat sealing temperature is 128°C. [4] In the total reflection infrared absorption spectrum of the sealing surface, -1 More than 983cm -1 The peak intensity of the absorption peak appearing in the first region below is P1, 700 cm -1 More than 750cm -1 The laminate according to any one of [1] to [3], wherein the peak intensity ratio P2 / P1 or P3 / P1 is 0.15 or less, or P4 / P3 is 1.5 or less, where P2 is the peak intensity of one absorption peak that appears in the second region below, P3 is the peak intensity of the absorption peak on the higher wavenumber side of the two absorption peaks with the largest peak intensities in the second region when two or more absorption peaks are present in the second region, and P4 is the peak intensity of the absorption peak on the lower wavenumber side of the two absorption peaks with the largest peak intensities in the second region when two or more absorption peaks are present in the second region. [5] The laminate according to any one of [1] to [4], wherein the sealant layer has a fusion strength of 10.0 N / 15 mm or less when heat-sealed to the same sealant layer under conditions of 135°C, 0.05 MPa, and 30 seconds. [6] The laminate according to any one of [1] to [5], further comprising a gas barrier layer. [7] A packaging bag obtained by using the laminate according to any one of [1] to [6] above and heat-sealing the sealing surfaces together. [8] The packaging bag according to [7], which is used for applications requiring heat treatment at 80°C or higher. [9] A sealant film containing a polypropylene resin, wherein when the surface of the sealant film is used as a sealing surface, the surface softening temperature of the sealing surface determined by local thermal analysis is 110°C or higher and 140°C or lower, and when the sealant film is heat-sealed to another sealant film at 121°C, 0.05 MPa, and for 30 seconds, the sealant film has a fusion strength of 2.0 N / 15 mm or lower.

[10] A packaging body comprising a packaging bag and contents contained in the packaging bag, wherein the packaging bag is formed using the laminate described in any one of [1] to [6], and the sealing surface forms the inner surface of the packaging bag.

[11] A moist heat treated package comprising a packaging bag and contents contained in the packaging bag, the packaging bag being formed using a laminate, the laminate comprising at least a base layer and a sealant layer, the surface softening temperature of the sealing surface of the sealant layer being 140°C or higher and 150°C or lower as determined by local thermal analysis, the base layer and the sealant layer containing a polypropylene-based resin, and the sealing surface constituting the inner surface of the packaging bag. [Explanation of symbols]

[0092] 10...base material layer, 20...intermediate layer, 30, 830...sealant layer, 30a, 830a...sealing surface, 100, 800...laminated body, 400, 900...packaging bag, 500...packaging body, 600...sealed body, 610...heat-sealed portion, 700...moisture-heat-treated packaging body, C...contents

Claims

1. The adhesive tape comprises at least a base layer and a sealant layer, and the surface softening temperature of the sealant layer measured by local thermal analysis is 110°C or higher and 140°C or lower; the sealant layer has a fusion strength of 2.0 N / 15 mm or less when heat-sealed to the same sealant layer under conditions of 121°C, 0.05 MPa, and 30 seconds; The laminate, wherein the base layer and the sealant layer contain a polypropylene-based resin.

2. 2. The laminate according to claim 1, wherein the surface softening temperature of the sealing surface measured by local thermal analysis after the laminate is subjected to a pressure and heat treatment under conditions of 0.33 MPa, 130°C, and 30 minutes is 140°C or higher and 150°C or lower.

3. When the sealant layer is heat-sealed to the same sealant layer as the sealant layer under conditions of 0.05 MPa and 30 seconds, the fusion strength when the heat sealing temperature is 121°C is T1 (N / 15 mm) and the fusion strength when the heat sealing temperature is 128°C is T2 (N / 15 mm), The laminate according to claim 1 or 2, wherein T2-T1 is 10.0 N / 15 mm or less.

4. In the total reflection infrared absorption spectrum of the sealing surface, －１ 983cm or more －１ The peak intensity of the absorption peak appearing in the first region below is P1, 700 cm －１ More than 750cm －１ When the peak intensity of one absorption peak appearing in the following second region is P2, and when two or more absorption peaks exist in the second region, the peak intensity of the absorption peak on the higher wavenumber side of the two absorption peaks having the largest peak intensities in the second region is P3, and the peak intensity of the absorption peak on the lower wavenumber side is P4, 3. The laminate according to claim 1, wherein the peak intensity ratio P2 / P1 or P3 / P1 is 0.15 or less, or the peak intensity ratio P4 / P3 is 1.5 or less.

5. 3. The laminate according to claim 1, wherein the sealant layer has a fusion strength of 10.0 N / 15 mm or less when heat-sealed to the same sealant layer under conditions of 135°C, 0.05 MPa, and 30 seconds.

6. The laminate according to claim 1 or 2, further comprising a gas barrier layer.

7. A packaging bag obtained by using the laminate according to claim 1 or 2 and heat-sealing the sealing surfaces together.

8. The packaging bag according to claim 7, which is used for applications in which a heat treatment at 80°C or higher is performed.

9. A sealant film containing a polypropylene-based resin, The surface softening temperature of the sealing surface of the sealant film measured by local thermal analysis is 110°C or higher and 140°C or lower, The sealant film has a fusion strength of 2.0 N / 15 mm or less when heat-sealed to another sealant film under conditions of 121°C, 0.05 MPa, and 30 seconds.

10. A packaging bag and contents contained in the packaging bag, The packaging bag is formed using the laminate according to claim 1 or 2, A package in which the sealing surface forms the inner surface of the packaging bag.

11. A packaging bag and contents contained in the packaging bag, The packaging bag is formed using a laminate, The laminate is The adhesive tape comprises at least a base layer and a sealant layer, and the surface softening temperature of the sealant layer measured by local thermal analysis is 140°C or higher and 150°C or lower; the base layer and the sealant layer contain a polypropylene-based resin, The moist heat treatment package, wherein the sealing surface constitutes the inner surface of the packaging bag.

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