Laminate, sealant film, packaging bag, package, and heat and moisture 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 heat and humidity treatment package.

Background Art

[0002] In recent years, the need for sustainable packaging materials that consider the environment has increased, and the development of packaging materials (monomaterial packaging materials) composed of laminates of layers containing the same material with good recyclability has been promoted.

[0003] Since the monomaterial packaging material has an inner layer and an outer layer containing the same material, it has poorer heat resistance of the outer layer than a packaging material (multimaterial packaging material) composed of a laminate having an inner layer and an outer layer made of different resins. Therefore, in the monomaterial packaging material, high heat resistance is required for the outer layer, and low melting point, that is, low heat sealability, is required for the inner layer.

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

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, even if the composite film described in Patent Document 1 has heat sealability at a low temperature (less than 155°C), when a wet heat treatment such as a retort treatment at a high temperature of about 120°C is performed on the packaging bag obtained using the composite film, the inner surfaces (sealing surfaces) of the packaging bag are fused to each other, and it has sealing surface fusion adhesion. On the other hand, when improving the resistance to sealing surface fusion adhesion, it may become impossible to achieve low-temperature heat sealability. The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a laminate, a sealant film, a packaging bag, a package, and a wet heat treatment package that have excellent resistance to sealing surface fusion adhesion even when subjected to wet heat treatment while having low-temperature heat sealability.

Means for Solving the Problems

[0007] One aspect of the present disclosure provides a laminate including at least a base material layer and a sealant layer, wherein the surface softening temperature of the sealing surface of the sealant layer by local thermal analysis is 110°C or higher and 140°C or lower, and when the sealant layer is heat-sealed with the same sealant layer at 121°C, 0.05 MPa, and for 30 seconds, it has a fusion strength of 2.0 N / 15 mm or less, and the base material layer and the sealant layer contain a polypropylene-based resin. The laminate has excellent resistance to sealing surface fusion adhesion even when subjected to wet heat treatment while having low-temperature heat sealability. Specifically, when the laminate is used to produce a packaging bag, when the sealing surfaces of the laminate are heat-sealed facing each other, heat sealing can be performed at a lower temperature compared to the case where the surface softening temperature by local thermal analysis of the sealing surface exceeds 140°C. Further, even when a wet heat treatment is performed on a package in which a packaging bag is produced by heat-sealing the sealing surfaces of the laminate and the package contains contents therein, the occurrence of fusion between the sealing surfaces can be suppressed compared to the case where the fusion strength exceeds 2.0 N / 15 mm.

[0008] It is preferable that the surface softening temperature of the sealing surface by local thermal analysis after heating and pressurizing the laminate under the conditions of 0.33 MPa, 130°C, and for 30 minutes is 140°C or higher and 150°C or lower. In this case, while the laminate has low-temperature heat sealability, it has better seal surface fusion resistance even when subjected to hydrothermal treatment. Therefore, even when a package is produced by heat-sealing the seal surfaces of the laminate to form a packaging bag and the package containing the contents in the packaging bag is subjected to hydrothermal treatment, the occurrence of fusion between the seal surfaces can be sufficiently suppressed.

[0009] In the above laminate, when the sealant layer is heat-sealed under the conditions of 0.05 MPa and 30 seconds with the same sealant layer as the sealant layer, if the fusion strength at a heat-sealing temperature of 121°C is T1 (N / 15 mm) and the fusion strength at a heat-sealing temperature of 128°C is T2 (N / 15 mm), it is preferable that T2 - T1 is 10.0 N / 15 mm or less. In this case, the laminate has seal surface fusion resistance even against hydrothermal treatment at 125°C or higher. Therefore, even when a package is produced by heat-sealing the seal surfaces of the laminate to form a packaging bag and the package containing the contents in the packaging bag is subjected to hydrothermal treatment at 125°C or higher, the occurrence of fusion between the seal surfaces can be suppressed.

[0010] In the total reflection infrared absorption spectrum of the above seal surface, the peak intensity of the absorption peak appearing in the first region above 963 cm -1 and below 983 cm -1 is P1, the peak intensity of one absorption peak appearing in the second region above 700 cm -1 and below 750 cm -1 is P2. When there are two or more absorption peaks in the second region, if the peak intensity of the absorption peak on the high-frequency side among the two absorption peaks with the largest peak intensity in the second region is P3 and the peak intensity of the absorption peak on the low-frequency 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 seal surface fusion resistance even when subjected to hydrothermal treatment. Therefore, even when a hydrothermal treatment is performed on a package obtained by using the laminate to heat-seal seal surfaces to form a packaging bag and containing contents in the packaging bag, the occurrence of fusion between the seal surfaces can be effectively suppressed.

[0011] When the above-mentioned sealant layer is heat-sealed with the same sealant layer under the 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 seal surface fusion resistance even against hydrothermal treatment at 130 °C or higher. Therefore, even when a hydrothermal treatment is performed at 130 °C or higher on a package obtained by using the laminate to heat-seal seal surfaces to form a packaging bag and containing contents in the packaging bag, the occurrence of fusion between the seal surfaces can be suppressed.

[0012] The above laminate preferably further includes a gas barrier layer. In this case, the gas barrier property of the laminate is further improved. Therefore, when a packaging bag is formed using the laminate and contents are contained in the packaging bag to form a package, deterioration of the contents due to gases such as oxygen can be effectively suppressed.

[0013] Another aspect of the present disclosure provides a packaging bag obtained by heat-sealing the above-mentioned seal surfaces using the above-mentioned laminate. This packaging bag has low-temperature heat-sealability and can suppress the occurrence of fusion between the seal surfaces even when subjected to hydrothermal treatment. The above packaging bag may be used for applications where heat treatment at 80 °C or higher is performed.

[0014] Another aspect of the present disclosure is a sealant film containing a polypropylene-based resin, wherein the surface softening temperature of the sealant surface of the sealant film by local thermal analysis is 110°C or higher and 140°C or lower, and when the sealant film is heat-sealed with the same sealant film at 121°C, 0.05 MPa, and for 30 seconds, it has a fusion strength of 2.0 N / 15 mm or less. Since this sealant film is heat-sealed at a low temperature, when producing a packaging bag using a laminate formed with a base material layer containing a polypropylene-based resin, if the sealant surfaces of the laminate are heat-sealed facing each other, the laminate can be heat-sealed at a low temperature. Further, when using a laminate formed with a base material layer containing a polypropylene-based resin, heat-sealing the sealant surfaces with each other, and producing a packaging bag having the sealant film as an inner layer, the occurrence of fusion between the sealant surfaces can be suppressed even when performing a wet heat treatment.

[0015] Still another aspect of the present disclosure provides a package including a packaging bag and contents accommodated in the packaging bag, wherein the packaging bag is formed using the above-described laminate, and the sealant surface constitutes the inner surface of the packaging bag. According to this package, the occurrence of fusion between the sealant surfaces of the packaging bag can be suppressed even when performing a wet heat treatment. Therefore, the package can be easily opened. Further, after opening the package, the contents can be easily taken out, and the contents can be sufficiently discharged. As a result, the packaging bag remaining after discharging the contents can have high recyclability. Further, according to the above package, since the laminate has low-temperature heat sealability, deterioration of layers other than the sealant layer in the laminate due to heat can be suppressed when the packaging bag is formed. Therefore, a decrease in the quality of the contents of the package can be suppressed.

[0016] Still other aspects of the present disclosure provide a packaging bag and contents contained in the packaging bag. The packaging bag is formed using a laminate, and the laminate includes at least a base material layer and a sealant layer. The surface softening temperature of the sealant surface of the sealant layer by local thermal analysis is 140°C or higher and 150°C or lower. The base material layer and the sealant layer contain a polypropylene-based resin, and the sealant surface constitutes the inner surface of the packaging bag, thereby providing a hydrothermal treatment package. According to this hydrothermal treatment package, since the laminate can suppress the fusion of the sealant surfaces of the packaging bag due to hydrothermal treatment, the fusion of the sealant surfaces of the hydrothermally treated packaging bag is suppressed. Therefore, the hydrothermal treatment package can be easily opened. Further, after opening the hydrothermal treatment package, the contents can be easily taken out, and the contents can be sufficiently discharged. As a result, the packaging bag remaining after discharging the contents can have high recyclability.

Advantages of the Invention

[0017] According to the present disclosure, there are provided a laminate, a sealant film, a packaging bag, a package, and a hydrothermal treatment package that have excellent sealant surface fusion resistance even when subjected to hydrothermal treatment while having low-temperature heat sealability.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0019] Hereinafter, embodiments of the present disclosure will be described. The same components are denoted by the same reference numerals, and redundant descriptions are omitted. Also, the dimensional ratios in the drawings are not limited to the illustrated ratios.

[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 an embodiment of the laminate of the present disclosure. As shown in FIG. 1, the laminate 100 includes at least a base material layer 10 and a sealant layer 30. The surface of the sealant layer 30 opposite to the base material layer 10 is the seal surface 30a. The base material layer 10 and the sealant layer 30 contain a polypropylene-based resin. In the sealant layer 30, the surface softening temperature by local thermal analysis of the seal surface 30a is 110°C or higher and 140°C or lower. Further, the sealant layer 30 has a fusion strength of 2.0 N / 15 mm or less when heat-sealed with the same sealant layer as the sealant layer 30 under the conditions of 121°C, 0.05 MPa, and 30 seconds.

[0021] The laminate 100 may further include an intermediate layer 20 between the base material layer 10 and the sealant layer 30. The laminate 100 may further include a printing layer as needed.

[0022] The laminate 100 has excellent seal surface fusion resistance even when subjected to a hydrothermal treatment while having low-temperature heat sealability. Specifically, when the laminate 100 is used to produce a packaging bag, when the seal surfaces 30a of the laminate 100 are heat-sealed facing each other, heat sealing can be performed at a lower temperature compared to the case where the surface softening temperature by local thermal analysis of the seal surface 30a exceeds 140°C. Further, even when the laminate 100 is used, the seal surfaces 30a are heat-sealed to produce a packaging bag and the packaged product containing the contents in the packaging bag is subjected to a hydrothermal treatment, the occurrence of fusion between the seal surfaces 30a can be suppressed compared to the case where the above fusion strength exceeds 2.0 N / 15 mm.

[0023] Hereinafter, the laminate 100, the base material layer 10, the sealant layer 30, the intermediate layer 20, and the printing layer will be described in detail.

[0024] (Laminate) The content rate of the polypropylene-based resin in the laminate 100 is not particularly limited, but is preferably 72% by mass or more. In this case, the recyclability of the laminate 100 can be improved. From the viewpoint of further improving the recyclability, the content rate 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 material 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 material layer 10 is composed of a resin containing propylene as a constituent unit. Examples of the polypropylene-based resin include homopolypropylene, a propylene copolymer 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-based resin may be block polypropylene which is a mixture of homopolypropylene and ethylene propylene rubber.

[0027] The base material layer 10 may be an unstretched film or a stretched film. The stretched film may be a uniaxially stretched film or a biaxially stretched film. Further, the base material layer 10 may be a laminate containing a stretched film and an unstretched film. The base material layer 10 preferably has a biaxially stretched film. In this case, the mechanical strength and dimensional stability of the laminate 100 can be improved.

[0028] The surface of the base material layer 10 on the sealant layer 30 side may be subjected to various pretreatment processes such as corona treatment, plasma treatment, ozone treatment, and flame treatment, or a coating layer such as an easy adhesion layer may be provided. The base material layer 10 may contain a resin other than polypropylene-based resin. Examples of such resins include polyolefin-based resins such as polyethylene-based resins. The base material layer 10 may contain at least one additive selected from fillers, antistatic agents, plasticizers, lubricants, antioxidants, etc., if necessary.

[0029] (Sealant layer) The sealant layer 30 is a layer that imparts heat sealability in the laminate 100 and contains a polypropylene-based resin. The polypropylene-based resin contains a resin having propylene as a constituent unit. Examples of the polypropylene-based resin include homopolypropylene, propylene copolymers obtained by copolymerizing propylene with α-olefins 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 propylene-ethylene random copolymer, propylene-ethylene block copolymer, propylene-ethylene terpolymer, etc. The polypropylene-based resin may be block polypropylene which is a mixture of homopolypropylene and ethylene propylene rubber.

[0030] The sealant layer 30 may be an unstretched film or a stretched film, but from the viewpoint of reducing the heat seal temperature and enhancing the sealability by heat seal, it is preferably an unstretched film.

[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. By making the thickness of the sealant layer 30 100 μm or less, it is easy to suppress the amount of heat required for heat sealing, and it is easy to reduce heat damage to the base material layer 10 and the intermediate layer 20 in the laminate 100.

[0033] (1) Surface softening temperature of the seal surface (1-1) Surface softening temperature B As described above, the surface softening temperature (hereinafter also referred to as "surface softening temperature B") of the seal surface 30a by local thermal analysis of the seal surface 30 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 that better seal surface fusion resistance is obtained even when subjected to a damp heat treatment compared to the case where the surface softening temperature B is less than 110°C. Also, when the surface softening temperature B is 140°C or lower, heat sealing can be performed at a lower temperature compared to the case where the surface softening temperature B exceeds 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 lower, 135°C or lower, 133°C or lower, or 130°C or lower.

[0034] For example, by including homopolypropylene or block polypropylene in the polypropylene-based resin used for the sealant layer 30, a sealant layer 30 having a high surface softening temperature B can be obtained. On the other hand, by including random polypropylene or an elastomer in the polypropylene-based resin, a sealant layer 30 having a low surface softening temperature B can be obtained. 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 substance such as a resin exhibits softening behavior. The surface softening temperature A in this embodiment is measured by performing local thermal analysis (LTA) on the seal surface 30a of the sealant layer 30 using an atomic force microscope (AFM). The surface softening temperature A is specifically calculated as follows. First, prepare the sealant layer 30. At this time, the sealant layer 30 itself may be prepared, or a laminate obtained by attaching another film such as the base material layer 10 to the sealant layer 30 may be prepared. To measure the surface softening temperature A, the sealant layer 30 is heated. This heating is performed by applying a voltage to a cantilever having a heater. In local thermal analysis (LTA), after measuring the shape of the surface (sealing surface 30a) of the sealant layer 30, a constant force (contact pressure) is applied to a predetermined location on the surface of the sealant layer 30 with a cantilever, and heating is performed while keeping the contact pressure constant. The temperature at which a change in the height position (Z displacement) of the cantilever occurs due to a change in the hardness of the sealing surface 30a before and after heating is calculated as the surface softening temperature. The change in the height position of the cantilever refers to the change caused by the upward vertical position of the cantilever due to the thermal expansion of the sealing surface 30a and the downward vertical position of the cantilever due to the softening of the sealing surface 30a. By converting the applied voltage of the heater of the cantilever into the surface softening temperature when such a change in the height position of the cantilever occurs, the local and near-surface softening temperature in the nanoscale region can be known.

[0036] To convert the applied voltage to the heater of the cantilever into the softening temperature, a calibration curve of the applied voltage and temperature is created. As calibration samples, four polymer materials with melting points different from each other by 50 °C or more are used. As these polymer materials, materials with melting points above the surface softening temperature of the sealant layer 30 and materials with melting points below the surface softening temperature are used. The melting point (melting peak temperature) of each calibration sample is measured in advance by a differential scanning calorimeter (DSC), and the melting point is taken as the surface softening temperature of the calibration sample. Local thermal analysis is performed at different measurement positions for each calibration sample, and a calibration curve is created by approximating the average value of the applied voltage at the obtained softening point and the softening temperature (melting point measured by DSC) of the calibration sample with a cubic function by the least squares method, and this calibration curve is used as the calibration curve.

[0037] Using this calibration curve of the applied voltage and temperature, the temperature corresponding to the applied voltage at the softening point is obtained, and this temperature is defined 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, the surface softening temperature (hereinafter also referred to as "surface softening temperature A") by local thermal analysis on the seal surface 30a after pressure and heat treatment under the conditions of 0.33 MPa, 130 °C, and 30 minutes is preferably 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 sealability. Further, when the surface softening temperature A is 140 °C or higher, it can have better resistance to seal surface fusion even after hydrothermal treatment. Therefore, even when hydrothermal treatment is performed on a package in which the laminate 100 is used to produce a packaging bag by heat-sealing the seal surfaces 30a of the laminate 100 and the contents are contained in the packaging bag, the occurrence of fusion between the seal surfaces 30a can be sufficiently suppressed. The surface softening temperature A may be 143 °C or higher, 145 °C or higher, or 146 °C or higher. Also, the surface softening temperature A may be 149 °C or lower or 148 °C or lower. The surface softening temperature A can be measured in the same manner as the surface softening temperature B.

[0039] Note that the above pressure and heat treatment is a treatment that simulates the influence of heat in hydrothermal treatment on the sealant layer 30.

[0040] (2) Fusion strength The sealant layer 30 has a fusion strength T1 of 2.0 N / 15 mm or less when heat-sealed with the same sealant layer as the sealant layer 30 under the conditions of 121 °C, 0.05 MPa, and 30 seconds. When the fusion strength T1 is 2.0 N / 15 mm or less, even when hydrothermal treatment is performed on a package in which the laminate 100 is used to produce a packaging bag by heat-sealing the seal surfaces 30a of the sealant layer 30 and the contents are contained in the packaging bag, the occurrence of fusion between the seal surfaces 30a can be suppressed. The fusion strength T1 may be 1.8 N / 15 mm or less, and may also be 1.6 N / 15 mm or less. The fusion strength T1 may be 0 N / 15 mm, or may be greater than 0 N / 15 mm. The fusion strength may also be 0.1 N / 15 mm or more, 0.3 N / 15 mm or more, or 0.5 N / 15 mm or more. The same sealant layer as the sealant layer 30 refers to a sealant layer having the same constituent materials and thickness as the sealant layer 30.

[0041] When the sealant layer 30 is heat-sealed with the same sealant layer as the sealant layer 30 under the conditions of 128 °C, 0.05 MPa, and 30 seconds, and the fusion strength is T2 (N / 15 mm), although 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 seal surface fusion even for hydrothermal treatment at 125 °C or higher. Therefore, even when the laminate 100 is used to produce a packaging bag by heat-sealing the seal surfaces 30a together, and the resulting package containing the contents is subjected to hydrothermal treatment at 125 °C or higher, the occurrence of fusion between the seal surfaces 30a can be suppressed. T2 - T1 may be 0 N / 15 mm, or may be greater than 0 N / 15 mm. When T2 - T1 is greater than 0 N / 15 mm, it may also be 0.1 N / 15 mm or more, 0.5 N / 15 mm or more, or 1.0 N / 15 mm or more.

[0042] When the sealant layer 30 is heat-sealed with the same sealant layer as the sealant layer 30 under the conditions of 135 °C, 0.05 MPa, and 30 seconds, it preferably has a fusion strength T3 of 10.0 N / 15 mm or less. In this case, the laminate 100 has seal surface fusion resistance even to hydrothermal treatment at 130°C or higher. Therefore, even when the laminate 100 is used to produce a packaging bag by heat-sealing the seal surfaces 30a together, and the resulting package containing the contents is subjected to hydrothermal treatment at 130°C or higher, the occurrence of fusion between the seal surfaces 30a can be suppressed. 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. Hereinafter, the method for measuring the fusion strength will be described with reference to FIG. 3. FIG. 3 is a plan view showing a seal body used for measuring the fusion strength of the sealant layer. First, prepare two films made of the sealant layer used for measurement. As shown in FIG. 3, both films are prepared such that the length in the flow direction (MD direction) during film formation is 60 mm and the length in the direction perpendicular to the MD direction (TD direction) during film formation is 120 mm. Then, the two films are overlapped, and a region with a width of 10 mm from the edge 600a in the TD direction is heated at a predetermined heat-sealing temperature (121°C, 128°C, or 135°C) while being pressurized at 0.05 MPa for 30 seconds to perform heat-sealing, thereby forming a heat-sealed portion 610 indicated by diagonal lines. In this way, the seal body 600 is obtained. The heat-sealed portion 610 is a region with a length of 10 mm in the MD direction and a length of 120 mm in the TD direction. Next, cut out the portion 620 indicated by the broken line in FIG. 3 from the seal body 600 to obtain a test piece with 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. Then, the tensile strength when the heat-sealed portion of the test piece is peeled is defined as the fusion strength under the heat-sealing conditions of the heat-sealed portion. In this way, the fusion strength is measured.

[0044] (3) Peak intensity ratio in the total reflection infrared absorption spectrum When measuring the total reflection infrared absorption spectrum of the sealing surface 30a, since the sealant layer 30 contains a polypropylene-based resin (for example, a random polypropylene copolymer), one absorption peak derived from the methyl group of the polypropylene-based resin appears in the first region of 963 cm ―1 or more and 983 cm ―1 or less. Further, when the polypropylene-based resin contained in the sealant layer 30 contains a methylene group, an absorption peak derived from the methylene group appears in the second region of 700 cm ―1 or more and 750 cm ―1 or less. This absorption peak splits into two absorption peaks due to a change in crystallinity when the content of the polyethylene-based resin in the sealant layer 30 increases or the type of the polypropylene-based resin becomes, for example, block polypropylene. Here, when the peak intensity of the absorption peak appearing in the first region is P1, when there is one absorption peak appearing in the second region, the peak intensity of that absorption peak is P2, and when two or more absorption peaks appear in the second region, among the two largest absorption peaks in the second region, if the peak intensity of the absorption peak on the high wavenumber side is P3 and the peak intensity of the absorption peak on the low 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 heat-sealing surface fusion resistance even when subjected to a damp heat treatment. Therefore, even when the laminate 100 is used to produce a packaging bag by heat-sealing the sealing surfaces 30a together and a damp heat treatment is performed on the package containing the contents in the packaging bag, the occurrence of fusion between the sealing surfaces 30a can be effectively suppressed.

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

[0046] P4 / P3 is preferably 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 infrared light through a prism onto the seal surface 30a of the sealant layer 30 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 contains a propylene copolymer and contains a large amount of propylene in the propylene copolymer, the proportion of methyl groups in the sealant layer 30 increases, so the value of P1 tends to increase. On the other hand, when the sealant layer 30 contains a large amount of materials containing methylene groups and having a low crystallinity, such as polyethylene or random polypropylene containing ethylene as a constituent unit, the absorption peak in the second region is less likely to split. At this time, the higher the proportion of polyethylene or ethylene in the propylene copolymer in the sealant layer 30, the greater the tendency for the value of P2 to be large. Also, when the sealant layer 30 contains a large amount of materials containing methylene groups and having a high crystallinity, such as block polypropylene, the absorption peak in the second region is likely to split. At this time, the higher the proportion of block polypropylene in the sealant layer 30, the greater the values of P3 and P4, and particularly the value of P4 is large. Therefore, by appropriately adjusting the type of polypropylene-based resin and the blending ratio of the polyethylene-based resin contained in the sealant layer 30, the peak intensity ratios P1 / P2, P3 / P2, and P3 / P4 can be adjusted to desired values.

[0049] (Intermediate layer) 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 a content is accommodated in the packaging bag to produce a package, deterioration of the content 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 deposition layer composed of an inorganic compound.

[0050] Examples of the inorganic compound constituting the vapor deposition layer include SiO X and AlO X and the like. When, for example, SiO X is used as the gas barrier layer, the gas barrier layer becomes transparent, so that the content can be visually recognized from the outside of the packaging bag. The vapor deposition layer can be formed of an inorganic compound such as SiO X or AlO X by using a vacuum vapor deposition method. The thickness of the vapor deposition 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 only of the 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 substrate layer 10 side or the sealant layer 30 side rather than the resin film.

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

[0052] Since the gas barrier layer is composed of a composite layer, in the gas barrier layer, reaction layers of both layers are formed at the interface between the vapor deposition layer and the coating layer, or a dense structure is formed by filling or reinforcing defects or micropores such as pinholes, cracks, and grain boundaries generated in the vapor deposition layer by the coating layer. Therefore, the gas barrier layer composed of a composite layer in which the coating layer and the vapor deposition layer are combined realizes higher gas barrier properties, moisture resistance, and water resistance, and has flexibility to withstand deformation by external force, so that the laminate 100 can be imparted with suitability 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 deposition layer and dried by heating. The coating agent can be mainly an aqueous solution or a water / alcohol mixed aqueous solution containing at least one of a water-soluble polymer and one or more alkoxides, their hydrolyzates, or tin chloride. The coating agent may further contain a silane monomer. In this case, the adhesion between the coating layer and the vapor deposition layer can be improved.

[0054] The above anchor coat layer can be formed using a curable compound (resin) such as urethane acrylate. The anchor coat layer can be formed by coating a paint in which a curable compound is dissolved in a solvent using a coating method applying a printing technique such as gravure coating or a generally known coating method.

[0055] The above resin film only needs to contain a resin. The resin is not particularly limited, but is preferably a polypropylene-based resin. Since the resin of the resin film is a polypropylene-based resin, the laminate 100 becomes even more recyclable. The resin film may be an unstretched film or a stretched film, but from the viewpoints of heat resistance and dimensional stability, it is preferably a stretched film. 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 according to the intended use of the laminate 100, and may be 10 μm or more, or may be 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) As described above, the laminate 100 may include a printing layer. The printing 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 printing layer is provided at a position visible from the outside of the laminate 100 for the purpose 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 in consideration of printability on other layers in the laminate 100, design properties such as color tone, adhesion, and safety as a food container. The printing method is also not particularly limited and is appropriately selected from known printing methods. As the printing method, for example, a gravure printing method, an offset printing method, a gravure offset printing method, a flexographic printing method, an inkjet printing method, etc. can be used. Among them, the gravure printing method can be preferably used from the viewpoints of productivity and high definition of the pattern.

[0057] [Sealing film] Next, an embodiment of the sealing film of the present disclosure will be described. The sealant film of the present disclosure is composed of the sealant layer 30 described above. That is, the sealant film contains a polypropylene-based resin, has a seal surface 30a, the surface softening temperature by local thermal analysis of the seal surface 30a is 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 the conditions of 121°C, 0.05 MPa, and 30 seconds.

[0058] Since this sealant film is heat-sealed at a low temperature, when producing a packaging bag using a laminate formed together with a base material layer containing a polypropylene-based resin, if the seal surfaces of the laminate are heat-sealed facing each other, the laminate can be heat-sealed at a low temperature. Further, when this sealant film is used with a base material layer containing a polypropylene-based resin to form a laminate, the seal surfaces are heat-sealed, and when producing a packaging bag having the sealant film as an inner layer, the occurrence of fusion between the seal surfaces 30a can be suppressed even when subjected to a hydrothermal treatment.

[0059] [Package] Next, an embodiment of the package of the present disclosure will be described with reference to FIG. 2. FIG. 2 is a cross-sectional view schematically showing an embodiment of the package of the present disclosure. As shown in FIG. 2, the package 500 includes a packaging bag 400 and contents C accommodated in the packaging bag 400. The packaging bag 400 is formed using a laminate 100, and the seal surface 30a constitutes the inner surface of the packaging bag 400. Specifically, the packaging bag 400 is formed by overlapping two laminates 100 with the seal surfaces 30a facing each other and heat-sealing the peripheral portions of the seal surfaces 30a. Therefore, the packaging bag 400 includes a main body portion 401 in which the contents C are accommodated and a seal portion 402 surrounding the main body portion 401.

[0060] The package 500 can suppress the fusion of the sealing surfaces 30a of the packaging bag due to the wet heat treatment. Therefore, when opening the package 500 by pulling the opposing sealing surfaces 30a of the packaging bag 400 away from each other, the package 500 can be easily opened. Further, after opening the package 500 by cutting out a part of the seal portion 402 to form an opening, the contents C can be easily taken out through the opening, and the contents C can be sufficiently discharged. As a result, the packaging bag 400 remaining after discharging the contents C can have high recyclability. Also, according to the package 500, since the laminate 100 has low-temperature heat sealability, when the packaging bag 400 is formed, deterioration due to heat of layers other than the sealant layer 30 in the laminate 100 (the base material layer 10 or the intermediate layer 20) can be suppressed. Therefore, a decrease in the quality of the contents C of the package 500 can be suppressed.

[0061] (Contents) The contents C are not particularly limited, and examples of the contents C include foods, pharmaceuticals, and the like. When the contents C are food, the package 500 can easily take out the contents C and sufficiently discharge the contents C after opening the package 500. Therefore, the package 500 can also reduce food loss.

[0062] (Packaging bag) In the present embodiment, the packaging bag 400 includes a main body portion 401 that houses the contents C 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 according to the 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. Note that the packaging bag 400 may be composed of three or more laminates 100. At this time, the plurality of laminates 100 constituting the packaging bag 400 may be made of different materials from each other, and may have different thicknesses, shapes, etc. from each other.

[0063] The packaging bag 400 may be used for applications that are heat-treated at 80°C or higher. Examples of the heat treatment include wet heat treatments such as retort treatment and boiling treatment.

[0064] [Wet Heat Treatment Package] Next, an embodiment of the wet heat treatment package of the present disclosure will be described with reference to FIG. 4. FIG. 4 is a cross-sectional view schematically showing an embodiment of the wet heat treatment package of the present disclosure. As shown in FIG. 4, the wet 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 a seal surface 830a constitutes the inner surface of the packaging bag 900. Specifically, the packaging bag 900 is formed by overlapping two laminates 800 with their seal surfaces 830a facing each other, heat-sealing the peripheral portions of the seal surfaces 830a, and then performing a wet heat treatment. Examples of the wet heat treatment include retort treatment and boiling treatment. The retort treatment is, for example, a pressurization and heat treatment under conditions of 0.33 MPa, 130°C, and 30 minutes, and the boiling treatment is, for example, a heat treatment under conditions of 80°C and 45 minutes. The laminate 800 includes a base material layer 10 and a sealant layer 830. The surface softening temperature of the seal surface 830a of the sealant layer 830 by local thermal analysis is 140°C or higher and 150°C or lower. The sealant layer 830 contains a polypropylene-based resin, and the seal surface 830a constitutes the inner surface of the packaging bag 900. The seal surface 830a is the surface of the sealant layer 830 on the side opposite to the base material layer 10. According to this heat and humidity treatment package 700, since it is possible to suppress the fusion of the seal surfaces 830a of the packaging bag 900 due to the heat and humidity treatment of the laminate 800, the fusion of the seal surfaces 830a of the retort-treated packaging bag 900 is suppressed. Therefore, the heat and humidity treatment package 700 can be easily opened. Further, after opening the heat and humidity treatment package 700, the content C can be easily taken out, and the content C can be sufficiently discharged. As a result, the packaging bag 900 remaining after discharging the content C can have high recyclability.

[0065] The surface softening temperature may be 143 °C or higher, 145 °C or higher, or 146 °C or higher. Also, the surface softening temperature may be 149 °C or lower or 148 °C or lower. The surface softening temperature can be measured in the same manner as 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 according to the 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, etc. Note that the packaging bag 900 may be composed of three or more laminates 800. At this time, the plurality of laminates 800 constituting the packaging bag 900 may be made of different materials, and may have different thicknesses, shapes, etc.

Example

[0067] Hereinafter, examples of the present disclosure will be specifically described. However, the form of the present disclosure is not limited to the following examples.

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

[0069] Next, a polyurethane-based adhesive was applied onto the surface of the gas barrier film on the vapor deposition layer side, and using this adhesive, a biaxially stretched polypropylene film (OPP1) with a thickness of 20 μm (manufactured by Futamura Chemical Co., Ltd., trade name "FOR") was laminated as a base material layer. At this time, as the polyurethane-based adhesive, the product name "Takelac A626 / Takenate A50" manufactured by Mitsui Chemicals, Inc. was used.

[0070] Next, the above polyurethane-based adhesive was applied onto the surface of the gas barrier film on the side opposite to the vapor deposition layer, and through this adhesive, a non-stretched polypropylene film (CPP film) with a thickness of 60 μm was laminated as a sealant layer. Thus, a laminate (base material layer / vapor deposition layer / resin film / sealant layer) was produced.

[0071] Regarding the above sealant layer, when the surface softening temperature B (before pressure and heat treatment), surface softening temperature A (after pressure and heat treatment), fusion strength T1 at 121°C, fusion strength T2 at 128°C, fusion strength T3 at 135°C, T2 - T1, and total reflection infrared absorption spectrum were calculated or measured as described later, the surface softening temperatures B and A, fusion strengths T1, T2, T3, T2 - T1, 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 produced in the same manner as in Example 1, except that a CPP film having a thickness, surface softening temperatures B and A, fusion strengths T1, T2, T3, T2 - T1, peak intensity ratios P2 / P1, P3 / P1, and P4 / P3 shown in Table 1 was used as the sealant layer.

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

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

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

[0076] At this time, when setting the contact pressure of the cantilever (the change amount of the deflection of the cantilever), the change amount of the Deflection voltage was set to 0.2 V, the voltage application acceleration (heating rate) was set to 0.5 V / second, and the maximum applied voltage was set to 5.5 V. After Detrend correction, the seal surface was heated. Then, after the seal surface expanded and the cantilever position rose, the seal surface was further heated until the seal surface softened and the cantilever position dropped by 10 nm, at which point the measurement was terminated. When the maximum applied voltage was reached without the vertical height (Z displacement) of the cantilever dropping by 50 nm from the change point, the maximum applied voltages during Detrend correction and measurement were increased by 0.5 V and the measurement was carried out again.

[0077] The applied voltage at the point where the vertical height (Z displacement) of the cantilever was the maximum was taken as the applied voltage 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 according to the measurement conditions of the sealant layer. As calibration samples, the following four types of polymer materials whose melting points (melting peak temperatures) were measured in advance by a differential scanning calorimeter (DSC) were used, and samples prepared in an environment below the glass transition temperature were used for each. · Polycaprolactone pellets (melting point: 60 °C) · Low-density polyethylene pellets (melting point: 112 °C) · Polypropylene pellets (melting point: 166 °C) · Biaxially oriented film of polyethylene terephthalate (melting point: 255 °C) The measurement conditions were as follows: the voltage application acceleration (heating rate) was 0.5 V / second, the maximum applied voltage was 3.5 V for polycaprolactone, 5 V for low-density polyethylene, 6 V for polypropylene, and 7.8 V for polyethylene terephthalate. When setting the contact pressure of the cantilever (the change in the deflection amount of the cantilever), the change in the Deflection voltage was set to 0.2 V. After Detrend correction, the seal surface was heated and the applied voltage at the softening point was measured. The applied voltage at the softening point was measured 10 times by changing the measurement position of the calibration sample, and a calibration curve was created by approximating the average value of the applied voltage at the softening point and the melting point (melting peak temperature) of the DSC measurement with a cubic function using the least squares method. This calibration curve was used as the calibration curve.

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

[0080] (1-2) Surface softening temperature A First, two sealant films with a size of 120 mm (MD direction) × 120 mm (TD direction) were prepared from the CPP film used as the sealant layer in the examples and comparative examples. Next, the seal surfaces of the two sealant films were faced 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 and sealed to produce a package. Next, the produced package was heated by spraying water at 130 °C for 30 minutes in an environment of 0.33 MPa, and then cooled by spraying water at 40 °C for 10 minutes in an environment of 0.33 MPa. Finally, the seal portion of the package was cut off, the water was drained, and the seal surface was dried. In this way, a sealant film subjected to heating and pressure treatment was prepared. Then, for the sealant film after the heat and pressure treatment, the surface softening temperature A was calculated in the same manner as the surface softening temperature B. The results are as shown in Table 1.

[0081] (2) Fusing strength The fusing strength was measured by a T-peel test. Specifically, first, two films made of the sealant layer used for measurement were prepared. The size of each film was 60 mm (MD direction) × 120 mm (TD direction). Then, the two films were overlapped, and a region with a width of 10 mm from the edge 600a in the TD direction was heated at a predetermined heat seal temperature (121 °C, 128 °C, or 135 °C) while being pressurized at 0.05 MPa for 30 seconds to perform heat sealing, forming a heat seal portion of 10 mm (MD direction) × 120 mm (TD direction) indicated by the hatching in Fig. 3. Thus, a sealed body was obtained. Next, from the sealed body, the portion 620 indicated by the broken line in Fig. 3 was cut out to obtain a test piece with a size of 15 mm (TD direction) × 60 mm (MD direction). Finally, a T-peel test was performed using the test piece. The T-peel test was conducted in accordance with JIS K 6854-3 under the following test conditions. And the tensile strength when the heat seal portion of the test piece was peeled off was taken as the fusing strength under the heat seal conditions of that heat seal portion. Thus, the fusing strength was measured. The results are as shown in Table 1. (Test conditions) · Distance between chucks: 15 mm · Tensile speed: 300 mm / min · Tensile direction: MD direction

[0082] (3) Peak intensity ratios P2 / P1, P3 / P1, P4 / P3 The peak intensity ratios P2 / P1, P3 / P1, P4 / P3 were calculated as follows. First, for the seal surface of the sealant layer, using a total reflection infrared absorption spectrometer (product name "Spectrum Spotlight 400 / Frontier", manufactured by PerkinElmer), the total reflection infrared absorption spectrum was measured under the following measurement conditions. (Measurement conditions) · Material of prism: diamond · Measurement frequency range: 400 - 4000 cm ―1 · Number of integrations: 16 times In the measured total reflection infrared absorption spectrum, the line connecting the minimum points at 1130 ± 5 cm -1 and 680 c ± 5 cm -1 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 - P4 were calculated. Finally, based on the calculated peak intensities P1 - P4, peak intensity ratios P2 / P1, P3 / P1, P4 / P3 were calculated. The results are as shown in Table 1.

[0083] <Seal surface fusion resistance> From the laminates prepared in the examples and comparative examples, test pieces 1 and 2 prepared under two different heating conditions were prepared as follows. Using these test pieces 1 and 2, the seal surface fusion resistance was judged and evaluated as follows. (1) Test piece 1 (heating conditions: 125°C, 30 min) First, two laminate pieces with a length of 120 mm in the MD direction and TD direction were cut out from the laminates prepared in the examples and comparative examples. Next, the two cut laminate pieces were overlapped so that the seal surfaces faced each other, and the four sides of the laminate pieces were heat - sealed with an impulse sealer in a state where the seal surfaces were in close contact to produce a fused body. While pressurizing the fused body in an environment of 0.21 MPa, it was heated by spraying hot water at 125°C for 30 minutes, and then cooled by spraying water at 40°C for 10 minutes in an environment of 0.21 MPa. After that, the fused body was left standing at room temperature for 1 day. For the fused body after standing, the heat - sealed parts on the four sides were cut off, and the central part of the remaining fused body was prepared as test piece 1.

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

[0085] (3) Judgment and evaluation of seal surface fusion resistance Regarding Test piece 1 and Test piece 2 prepared as described above, two laminated body pieces were each grasped by hand and peeled apart from each other. Based on the resistance felt during peeling, a five-level judgment criterion was established as follows for judgment. The results of the judgment are shown in Table 1. (Judgment criterion) 1: There is no resistance felt during peeling 2: There is almost no resistance felt during peeling 3: There is a slight resistance felt during peeling 4: There is a large resistance felt during peeling 5: The test piece is fused and there is a considerably large resistance felt (accompanied by deformation or appearance change of the seal surface (such as cohesive peeling) during peeling) Note that for test pieces with judgments of "1" and "2", they were evaluated as "◎", for test pieces with a judgment of "3", they were evaluated as "〇", for test pieces with a judgment of "4", they were evaluated as "△", and for test pieces with a judgment of "5", they were 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 start temperature of the sealant layer used in the examples and comparative examples. The seal start temperature of the sealant layer was measured as follows. First, as shown in Figure 3, two sealant layers with a size of 120 mm (TD direction) × 60 mm (MD direction) were prepared. These two sealant layers were heat-sealed at a seal width of 10 mm while being pressurized at 0.2 MPa for 1 second and heated at T °C to prepare a heat-sealed body. At this time, heat-sealed bodies prepared with T set at different heating temperatures of 2 °C intervals between 130 °C and 170 °C were each prepared. Then, test pieces with a size of 60 mm (TD direction) × 15 mm (MD direction) were prepared from these heat-sealed bodies. For each of the plurality of test pieces prepared as described above, a T-peel test was conducted. The T-peel test was carried out in accordance with JIS K 6854-3. In the T-peel test, specifically, T-peel was performed in the MD direction under the conditions of a chuck distance of 15 mm and a tensile speed of 300 mm / min. Then, the lowest temperature at which the peel strength became 10 N / 15 mm or more was defined as the seal start temperature of the sealant layer.

[0087] The low-temperature heat sealability of the sealant layer was evaluated based on the following evaluation criteria. The results are shown in Table 1. (Evaluation Criteria) 〇: The seal start temperature is less than 155°C ×: The seal start temperature is 155°C or more

[0088]

Table 1

[0089] From the results shown in Table 1, in Examples 1 to 9, the seal start temperature was less than 155°C, and the judgment of the seal surface fusion resistance under each heating condition of "125°C, 30 min" and "130°C, 30 min" was 1 to 4. It was confirmed that the laminate had low-temperature heat sealability and no fusion occurred between the seal surfaces. On the other hand, in Comparative Example 1, the seal start temperature was 156°C, which was 155°C or more. Also, in Comparative Examples 2 and 3, the judgment of the seal surface fusion resistance under each heating condition of "125°C, 30 min" and "130°C, 30 min" was 5, and it was confirmed that fusion occurred between the seal surfaces.

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

[0091] The outline of the present disclosure is as follows. [1] A laminate comprising at least a base material layer and a sealant layer, wherein the surface softening temperature by local thermal analysis of the seal surface of the sealant layer is 110°C or higher and 140°C or lower, and when the sealant layer is heat-sealed with the same sealant layer at 121°C, 0.05 MPa, and for 30 seconds, it has a fusion strength of 2.0 N / 15 mm or less, and the base material layer and the sealant layer contain a polypropylene-based resin. [2] The laminate according to [1], wherein the surface softening temperature by local thermal analysis of the seal surface after subjecting the laminate to pressure and heat treatment at 0.33 MPa, 130°C, and for 30 minutes is 140°C or higher and 150°C or lower. [3] When the sealant layer is heat-sealed with the same sealant layer at 0.05 MPa and for 30 seconds, and when the fusion strength at a heat-sealing temperature of 121°C is T1 (N / 15 mm) and the fusion strength at a heat-sealing temperature of 128°C is T2 (N / 15 mm), the laminate according to [1] or [2], wherein T2 - T1 is 10.0 N / 15 mm or less. [4] In the total reflection infrared absorption spectrum of the seal surface, the peak intensity of the absorption peak appearing in the first region of 963 cm -1 or higher and 983 cm -1 or lower is P1, the peak intensity of one absorption peak appearing in the second region of 700 cm -1 or higher and 750 cm -1 or lower is P2. When there are two or more absorption peaks in the second region, the peak intensity of the absorption peak on the high-frequency side among the two absorption peaks with the largest peak intensity in the second region is P3, and the peak intensity of the absorption peak on the low-frequency side is P4. 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. [5] The laminate according to any one of [1] to [4], wherein when the sealant layer is heat-sealed with the same sealant layer at 135°C, 0.05 MPa, and for 30 seconds, it has a fusion strength of 10.0 N / 15 mm or less. [6] The laminate according to any one of [1] to [5], further comprising a gas barrier layer. [7][1] A packaging bag obtained by heat-sealing the seal surfaces of the laminate described in [1] to [6]. [8] The packaging bag described in [7], which is used for applications that are heat-treated at 80°C or higher. [9] A sealant film containing a polypropylene-based resin, when the surface of the sealant film is used as the seal surface, the surface softening temperature by local thermal analysis of the seal surface is 110°C or higher and 140°C or lower, and when the sealant film is heat-sealed with the same sealant film at 121°C, 0.05 MPa, and 30 seconds, it has a fusion strength of 2.0 N / 15 mm or less. A sealant film.

[10] A package comprising a packaging bag and contents contained in the packaging bag, the packaging bag being formed using the laminate according to any one of [1] to [6], and the seal surface constituting the inner surface of the packaging bag.

[11] A 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 material layer and a sealant layer, the surface softening temperature by local thermal analysis of the seal surface of the sealant layer being 140°C or higher and 150°C or lower, the base material layer and the sealant layer containing a polypropylene-based resin, and the seal surface constituting the inner surface of the packaging bag. A moist heat treatment package.

Explanation of reference numerals

[0092] 10... Base material layer, 20... Intermediate layer, 30, 830... Sealant layer, 30a, 830a... Seal surface, 100, 800... Laminate, 400, 900... Packaging bag, 500... Package, 600... Seal body, 610... Heat-sealing part, 700... Moist heat treatment package, C... Contents

Claims

1. A laminate comprising at least a base layer and a sealant layer, the laminate is subjected to a pressure and heat treatment under conditions of 0.33 MPa, 130° C., and 30 minutes, and then the surface softening temperature of the sealing surface of the sealant layer is determined by local thermal analysis and is then 146.3° C. or higher and 147.4° C. or lower; The surface softening temperature of the seal surface of the sealant layer as determined by local thermal analysis is 113.6° C. or higher and 133.1° C. or lower; the base layer and the sealant layer contain a polypropylene-based resin, the polypropylene-based resin contained in the sealant layer contains a methyl group and a methylene group, The sealant layer is a non-oriented polypropylene film, 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), the fusion strength when the heat sealing temperature is 128° C. is T2 (N / 15 mm), and the fusion strength when the heat sealing temperature is 135° C. is T3 (N / 15 mm), T1 is 0.1 N / 15 mm or more and 1.5 N / 15 mm or less, T2 is 0.2 N / 15 mm or more and 6.5 N / 15 mm or less, and T3 is 1.5 N / 15 mm or more and 27.2 N / 15 mm or less, In the total reflection infrared absorption spectrum of the sealing surface, the peak intensity of an absorption peak appearing in a first region of 963 cm -1 to 983 cm -1 is defined as P1, the peak intensity of one absorption peak appearing in a second region of 700 cm -1 to 750 cm -1 is defined as 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 defined as P3, and the peak intensity of the absorption peak on the lower wavenumber side is defined as P4. A laminate having a peak intensity ratio P2 / P1 of 0.10 or more and 0.11 or less, or P3 / P1 of 0.08 or more and 0.26 or less and P4 / P3 of 0.68 or more and 1.69 or less.

2. The laminate of claim 1 further comprising a gas barrier layer.

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

4. The packaging bag according to claim 3, which is used in applications where a heat treatment at 80°C or higher is performed.

5. A sealant film containing a polypropylene-based resin, the sealant film is subjected to a pressure and heat treatment under conditions of 0.33 MPa, 130° C., and 30 minutes, and then the surface softening temperature of the sealing surface of the sealant film is determined by local thermal analysis and is 146.3° C. or higher and 147.4° C. or lower; The surface softening temperature of the sealant film by local thermal analysis is 113.6° C. or more and 133.1° C. or less, The sealant film is a non-oriented polypropylene film, The polypropylene-based resin contains a methyl group and a methylene group, The thickness of the sealant film is 20 μm or more, When the sealant film is heat-sealed to the same sealant film as the sealant film 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), the fusion strength when the heat sealing temperature is 128° C. is T2 (N / 15 mm), and the fusion strength when the heat sealing temperature is 135° C. is T3 (N / 15 mm). T1 is 0.1 N / 15 mm or more and 1.5 N / 15 mm or less, T2 is 0.2 N / 15 mm or more and 6.5 N / 15 mm or less, and T3 is 1.5 N / 15 mm or more and 27.2 N / 15 mm or less, In the total reflection infrared absorption spectrum of the sealing surface, the peak intensity of an absorption peak appearing in a first region of 963 cm -1 to 983 cm -1 is defined as P1, the peak intensity of one absorption peak appearing in a second region of 700 cm -1 to 750 cm -1 is defined as 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 defined as P3, and the peak intensity of the absorption peak on the lower wavenumber side is defined as P4. A sealant film having a peak intensity ratio P2 / P1 of 0.10 or more and 0.11 or less, or a peak intensity ratio P3 / P1 of 0.08 or more and 0.26 or less and a peak intensity ratio P4 / P3 of 0.68 or more and 1.69 or less.

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