package

Abstract

To provide a package that is improved such that the conditions of thermal fusion are easy to adjust.SOLUTION: According to the present invention, there is provided a package for storing contents in a sealed state, and the package comprises a lid part and a container, wherein the lid part has a sealant layer, a base material layer and a paper layer stacked in this order, the sealant layer is thermally welded to the container, and the base material layer is formed of resin and has a higher fusion point than the sealant layer. The lower of the MD-directional Young's modulus and the TD-directional Young's modulus of the material of the base material layer may be equal to or larger than 800 MPa.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a package. [Background technology]

[0002] Patent Document 1 discloses a technology for hermetically sealing and preserving the contents by heat-sealing a lid to a container. The lid is made of a resin film. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-106831 A Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors of the present application have been conducting intensive research into heat-welding a paper lid to a container via a sealant layer in order to use a paper lid instead of a resin film. However, a new problem has arisen in that it is difficult to properly adjust the heat-welding conditions when carrying out such heat-welding.

[0005] The present invention has been made in consideration of the above circumstances, and provides a package that is improved so that the heat sealing conditions can be easily adjusted. [Means for solving the problem]

[0006] According to the present invention, the following inventions are provided. [1] A packaging body for storing contents in a sealed state, the packaging body comprising a lid and a container, the lid being formed by stacking a sealant layer, a base layer and a paper layer in that order, the sealant layer being heat-welded to the container, the base layer being formed from a resin, and the melting point of the base layer being higher than the melting point of the sealant layer. [2] A packaging body according to the above [1], wherein the lower of the Young's modulus in the MD direction and the Young's modulus in the TD direction of the material of the base material layer is 800 MPa or more. [3] A packaging body according to the above [1] or [2], wherein the packaging body is a packaging body for microwave heating. [4] The packaging body according to any one of [1] to [3], wherein the base layer is formed of a polyester-based resin, a polyamide-based resin, or an olefin-based resin. [5] A packaging body according to any one of [1] to [3], wherein the container is constructed by laminating a paper material layer and a container resin layer, and the sealant layer is heat-welded to the container resin layer.

[0007] As a result of intensive research, the inventors discovered that by sandwiching a base layer having a higher melting point than that of the sealant layer between the paper layer and the sealant layer, it becomes easier to adjust the conditions for heat welding the lid portion, which led to the completion of the present invention. [Brief description of the drawings]

[0008] [Figure 1] This is a perspective view of a microwave oven package 1 according to one embodiment of the present invention. The dashed and dotted lines in the figure indicate the boundary lines where the curvature of the faces that make up the surface shape changes. The same is true for the other figures. [Diagram 2] 2A is a plan view of the package 1 of FIG. 1, FIG. 2B is a cross-sectional view taken along line BB in FIG. 2A, and FIG. 2C is an enlarged cross-sectional view showing the region indicated by the dashed line J in FIG. 2B. [Diagram 3] FIG. 3 is an enlarged view of an area A in FIG. [Figure 4] FIG. 4A is an explanatory diagram of a method for measuring the peel strength Q between the paper material layer 3a and the container resin layer 3b, and FIG. 4B is an explanatory diagram of a method for measuring the peel strength P between the lid portion 2 and the container 3 at the steam exhaust portion 7. [Diagram 5] FIG. 5A is an oblique view of a cut-out area near the steam exhaust section 7, and FIG. 5B is a view corresponding to FIG. 5A, showing a state in which the area 7c near the steam exhaust section 7 expands as the internal pressure of the packaging body 1 increases. [Figure 6]FIG. 2 is a perspective view for explaining a manufacturing method of the packaging body 1. [Figure 7] 7A is a perspective view of the seal bar 9 in FIG. 6, and FIG. 7B is an enlarged view of region B in FIG. 7A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present invention will be described. Various features shown in the following embodiments can be combined with each other. Also, each feature can be an invention independently.

[0010] 1. Structure of microwave oven package 1 As shown in Figures 1 to 7, a microwave package 1 according to one embodiment of the present invention is used for storing contents F in a sealed state. This package 1 comprises a lid 2 and a container 3 sealed by the lid 2. The lid 2 is a thin paper sheet. The contents F may be food that contains moisture and can be heated or cooked in a microwave oven, such as a retort food.

[0011] 1.1. Configuration of Container 3 The container 3 is a paper material container formed by laminating a paper material layer 3a and a container resin layer 3b bonded thereto. The paper material layer 3a can be made of a paper material such as pulp. The paper material layer 3a is preferably a pulp mold. A pulp mold is a molded product made of pulp (wood fiber) and can be formed by drawing up pulp dispersed in water in a mold and then drying it. When the container 3 is formed by deep drawing, wrinkles are likely to be formed in the flange portion 5, but with pulp mold, a container 3 without wrinkles in the flange portion 5 can be formed, so that the welding accuracy of the lid portion 2 to the flange portion 5 is improved. The container resin layer 3b can be made of any resin that can be heat-sealed with the lid portion 2, and can be made of polyolefin resins such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer, and ethylene-propylene block copolymer. The melting point of the container resin layer 3b is determined by the resin material used, and as an example, when low-melting point polypropylene is used, the melting point is about 143°C. The container resin layer 3b can be bonded to the paper material layer 3a with an adhesive.

[0012] The thickness of the paper material layer 3a is, for example, 300 to 1000 μm, and preferably 500 to 800 μm. Specifically, the thickness may be, for example, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, or 1000 μm, or may be within a range between any two of the numerical values ​​exemplified here. The thickness of the container resin layer 3b is, for example, 40 to 160 μm, and preferably 60 to 120 μm. Specifically, the thickness may be, for example, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, or 160 μm, or may be within a range between any two of the numerical values ​​exemplified here.

[0013] As shown in Fig. 4A, the peel strength Q between the paper material layer 3a and the container resin layer 3b can be obtained by cutting a flat part of the container 3 to a size of width W (mm) x 100 mm, peeling the paper material layer 3a and the container resin layer 3b at a part 50 mm long from the end to prepare a test piece 12, holding the parts 12a and 12b corresponding to the paper material layer 3a and the container resin layer 3b, respectively, with jigs 11a and 11b, and moving the jig 11b upward at 300 mm / min while the jig 11a is fixed, and dividing the maximum value of the load measured by the width W of the test piece. W is, for example, 5 to 15 mm, specifically, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15 mm, and may be within a range between any two of the numerical values ​​exemplified here. The peel strength Q is, for example, 5 to 20 gf / mm, specifically, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 gf / mm, and may be within a range between any two of the numerical values ​​exemplified here.

[0014] The container 3 has a container body 4 formed in a concave shape capable of accommodating the contents F, and an annular flange portion 5 provided so as to extend outward from an upper end 4a of the container body 4. The flange portion 5 is provided with a heat-sealed portion 6 at which the flange portion 5 and the lid portion 2 are heat-sealed. The heat-sealed portion 6 is annular and provided around the entire circumference of the flange portion 5. Therefore, the flange portion 5 and the lid portion 2 are heat-sealed at the heat-sealed portion 6, whereby the contents F are sealed within the package 1.

[0015] The heat-sealed portion 6 includes a steam exhaust portion 7 for exhausting steam generated by heating the contents F in a microwave oven. The steam exhaust portion 7 is a portion that is more easily peeled off than the other portion 6a of the heat-sealed portion 6, and when the internal pressure of the package 1 increases with heating of the contents F, the lid portion 2 and the flange portion 5 are preferentially peeled off at the steam exhaust portion 7, thereby enabling the exhaust of steam through the steam exhaust portion 7. This configuration prevents steam from leaking from unintended portions and prevents the package 1 from bursting due to failure to exhaust steam.

[0016] The steam exhaust portion 7 is preferably configured by curving a part of the heat-sealed portion 6 toward the inner edge 5a of the flange portion 5. In this case, the steam exhaust portion 7 has a substantially V-shape. With such a shape, the peeling force generated as the internal pressure of the package 1 increases is likely to be concentrated at the tip A of the steam exhaust portion 7, making peeling at the steam exhaust portion 7 even easier.

[0017] The peel strength P between the lid 2 and the container 3 at the steam exhaust section 7 is preferably 100 to 250 kgf, more preferably 120 to 220 kgf. If the peel strength P is too low, the timing of peeling at the steam exhaust section 7 when heated in a microwave oven may be too early, making it difficult to increase the heating effect of the contents, that is, the heating property may be poor. If the peel strength P is too high, the internal pressure of the package 1 may be too high before peeling at the steam exhaust section 7 occurs, causing the container 3 to deform, or when opening the lid 2 after peeling at the steam exhaust section 7, the paper material layer 3a and the container resin layer 3b may peel off, making it difficult to open. The peel strength P is preferably 120 to 220 kgf. The peel strength P is specifically, for example, 100, 105, 110, 115, 120, 125, 130, 133, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200, 205, 207, 210, 215, 220, 225, 230, 235, 240, 242, 245, or 250 kgf, and may be within a range between any two of the numerical values ​​exemplified here.

[0018] The peel strength P can be determined from the maximum load measured when a 10 mm wide portion 7h is cut out of a 10 mm wide portion 7h, which is centered on a bisector 7g of the corner on the side of the steam exhaust portion 7, defined by a pair of line segments S1 connecting the tip A of the steam exhaust portion 7 and a pair of bases 7a on the inner edge side of the steam exhaust portion 7, to a size of 10 mm x 100 mm so as to include a portion between the inner edge 5a and the outer edge 5c of the flange portion 5, and portions 10a and 10b of the test piece 10 corresponding to the inside of the container 3 and the lid portion 2 are held by jigs 11a and 11b, as shown in Fig. 4B, and the jig 11b is moved upward at 300 mm / min while the jig 11a is fixed. At this time, peeling of the steam exhaust portion 7 progresses from the tip A side.

[0019] 3, the portion on the tip A side of a first line segment 7e connecting a pair of bases 7a is the steam exhaust portion 7. The distance between the tip A and an intersection C of the bisector 7g and the first line segment 7e is, for example, 4 to 10 mm (6.4 mm in this embodiment), and specifically, for example, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, or 10 mm, and may be within a range between any two of the numerical values ​​exemplified here.

[0020] The average line width of the steam exhaust part 7 is preferably smaller than the average line width of the other parts 6a of the heat-sealed part 6. The average line width of the steam exhaust part 7 is calculated by dividing the area of ​​the part on the tip A side of the first line segment 7e by the longitudinal length of the steam exhaust part 7. The average line width of the other parts 6a is calculated by dividing the area of ​​the part on the side farther from the tip A than the base 7a by the longitudinal length of the other parts 6a. In other words, the longitudinal length is the length of the center line in the line width direction. The value of {average line width of the steam exhaust part 7 / average line width of the other parts 6a} is, for example, 0.01 to 0.9 (0.20 in this embodiment), preferably 0.05 to 0.5, and more preferably 0.1 to 0.4. Specifically, this value is, for example, 0.01, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, or 0.90, and may be within a range between any two of the numerical values ​​exemplified here or equal to or less than any one of them.

[0021] The average line width of the steam exhaust portion 7 is, for example, 0.5 to 2.0 mm (1 mm in this embodiment), specifically, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2.0 mm, and may be within a range between any two of the numerical values ​​exemplified here.

[0022] As shown in Fig. 3, if the length of the first line segment 7e connecting the pair of bases 7a is L1, the point where a straight line passing through the tip A and parallel to the first line segment 7e reaches the inner edge of the heat-sealed portion 6 is B, and the length of the second line segment 7f connecting the tip A and point B is L2, then L2 / L1 ≥ 1.0 (1.3 in this embodiment). The larger the value of L2 / L1 ≥ 1.0, the more likely the region 7c adjacent to the steam exhaust portion 7 is to expand due to the internal pressure caused by the steam from the contents F, as shown in Figs. 5A and 5B, and as a result, the peeling force generated with the increase in the internal pressure of the package 1 is more likely to be concentrated at the tip A of the steam exhaust portion 7, making peeling at the steam exhaust portion 7 even easier. L2 / L1 is, for example, 1.0 to 3.0, preferably 1.1 to 1.8, and more preferably 1.2 to 1.6. Specifically, this value is, for example, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.5, or 3.0, and may be within a range between any two of the numerical values ​​exemplified here or equal to or greater than any one of them.

[0023] 3, the angle formed by the line segment S1 connecting the tip A and the base 7a and the line segment S2 connecting the base 7a and point B is preferably 91 to 120 degrees (102 degrees in this embodiment). In this case, the peeling force generated with an increase in the internal pressure of the package 1 is more likely to be concentrated at the tip A of the steam exhaust section 7, making peeling at the steam exhaust section 7 even easier. Specifically, this angle is, for example, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, or 120 degrees, and may be within a range between any two of the numerical values ​​exemplified here.

[0024] The angle (90 degrees in this embodiment) between a pair of line segments S1 connecting the tip A and the base 7a is preferably 60 to 120 degrees, and more preferably 80 to 110 degrees. Specifically, this angle is, for example, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, or 120 degrees, and may be within a range between any two of the numerical values ​​exemplified here.

[0025] It is preferable that the steam discharge part 7 is curved so that the portion 7b between the tip A and the base 7a is convex toward the outer edge 7d of the steam discharge part 7. In this case, the distance between the pair of portions 7b narrows and the distance between the pair of bases 7a widens near the tip A, making peeling at the steam discharge part 7 easier near the tip A and widening the steam discharge path after peeling.

[0026] It is preferable that the tip A of the steam discharge part 7 is sharp. In this case, peeling at the tip A becomes easier.

[0027] The heat-sealed portion 6 preferably includes a transition portion 8 adjacent to the steam exhaust portion 7, the line width of which gradually narrows toward the steam exhaust portion 7. The transition portion 8 is preferably formed by bringing the inner edge of the transition portion 8 closer to the outer edge of the flange portion 5. In this case, the region 7c adjacent to the steam exhaust portion 7 becomes wider, making peeling at the steam exhaust portion 7 even easier. The transition portion 8 is part of the other portion 6a.

[0028] The maximum value of the angle between the outer edge and the inner edge of the transition portion 8 is, for example, 5 to 30 degrees (12 degrees in this embodiment), and preferably 8 to 15 degrees. Specifically, this maximum value is, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 degrees, and may be within a range between any two of the numerical values ​​exemplified here.

[0029] The heat-sealed portion 6 is preferably provided on the flat surface of the flange portion 5. The container 3 is formed from a material containing a paper material such as pulp, but such a material has poor moldability compared to resin, and it may be difficult to form ribs with high precision on the flange portion 5. For this reason, by providing the heat-sealed portion 6 on the flat surface of the flange portion 5, it becomes possible to form the heat-sealed portion 6 with high precision, regardless of the material constituting the container 3.

[0030] It is preferable that the flange portion 5 is provided with a wide portion 5b. The wide portion 5b is a portion whose width (the distance between the inner edge and the outer edge of the flange portion 5) is wider than the average width of the entire flange portion 5. It is preferable that the steam exhaust portion 7 is provided in the wide portion 5b. This makes it possible to provide the steam exhaust portion 7 without widening the entire width of the flange portion 5 to match the steam exhaust portion 7 or protruding the inner edge 5a of the flange portion 5 toward the inside of the container 3. It is also preferable that the outer edge 5c of the flange portion 5 is rectangular in plan view, the corners of which may be chamfered, and the wide portion 5b is preferably provided at a corner of the rectangle. Note that the plan view means that the microwave oven package 1 is viewed vertically from above.

[0031] The flange portion 5 is preferably provided with an inclined portion 5e that is inclined downward along the outer edge 5c of the flange portion 5. By providing the inclined portion 5e, the rigidity of the flange portion 5 is increased and the container resin layer 3b of the container 3 is prevented from peeling off from the paper material layer 3a.

[0032] 1.2. Configuration of the lid 2 The lid 2 is preferably made of a thin paper sheet having an outer edge of approximately the same size as that of the flange 5. The lid 2 includes a paper layer 2a, a base layer 2b, and a sealant layer 2c, which are stacked in this order. If the lid 2 and the flange 5 come into close contact at the steam exhaust section 7 after steam is released from the steam exhaust section 7, the inside of the package 1 may become depressurized when the package 1 cools down, causing the package 1 to deform. However, if the lid 2 has heat shrinkability, the lid 2 shrinks, making it difficult for the lid 2 and the flange 5 to come into close contact, and the shrinkage force of the lid 2 warps the flange 5, making it possible to suppress the close contact between the lid 2 and the flange 5.

[0033] By making the lid 2 out of paper, it is possible to meet the needs of reducing the environmental impact. There is no limitation on the material and manufacturing method of the paper material constituting the paper layer 2a, and various wrapping paper materials can be used. The paper layer 2a may be a thin paper sheet, for example, about 55 μm thick. An outer layer such as a printed layer may be laminated on the outer surface of the paper layer 2a.

[0034] The base layer 2b is made of a resin. Specifically, the material of the base layer 2b may be a polyester resin such as polyethylene terephthalate, a polyamide resin such as nylon 6, or an olefin resin such as polyethylene or polypropylene. The melting point of the base layer 2b is determined according to the type of resin material, and if a mixed resin is used, the melting point is determined by the ratio of the resin materials.

[0035] The sealant layer 2c can be formed of a polyolefin resin such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer, or ethylene-propylene block copolymer, and more specifically, unstretched polypropylene or linear low-density polyethylene can be used. More preferably, an easy-peel sealant in which polyethylene and polypropylene are mixed in a predetermined ratio can be used. This makes it easier to peel the lid 2 from the flange 5.

[0036] Here, it is also possible to adjust the peel strength by changing the ratio of the resins to be mixed. For example, when the container body 4 is polypropylene, the adhesive strength can be increased by increasing the ratio of polypropylene contained in the mixed resin, and conversely, the peelability can be increased by decreasing the ratio. As an example, the ratio may be PP:PE=3:1, but is not limited to this. When PE is expressed as 1 time and PP is expressed as M times (PP:PE=M:1), this M is, for example, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5 or 10, and this M may be a value within the range between any two of the numerical values ​​exemplified here. The melting point of the sealant layer 2c is determined according to the type of resin material and its mixing ratio.

[0037] The melting point of the base material layer 2b is higher than that of the sealant layer 2c. Thus, it was found that by sandwiching the base material layer 2b, which has a higher melting point than the sealant layer 2c, between the paper layer 2a and the sealant layer 2c, it becomes easier to adjust the conditions for heat welding the lid portion 2. The base material layer 2b prevents the paper layer 2a from participating in the welding, and thus prevents the paper layer 2a from breaking.

[0038] The difference between the melting point of the base layer 2b and the melting point of the sealant layer 2c is ΔT MP Then, this ΔT MP For example, ΔT is 10 to 150° C., preferably 20 to 140° C., and more preferably 40 to 110° C. MP Specifically, for example, is 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150°C, and may be within a range between any two of the numerical values ​​exemplified here.

[0039] For example, when nylon is used, the melting point of the base material layer 2b is about 221°C. When the sealant layer 2c is a mixed resin layer of PE and PP, for example, with a mixing ratio of PP:PE=3:1, the melting point of the sealant layer 2c is about 154°C. ΔT in this caseMP is approximately 67°C.

[0040] There is no limit to the thickness of the lid part 2, and there is no limit to the thickness of each layer constituting the lid part 2. If half of the total weight of the lid part 2 is made of paper, the lid part 2 as a whole is treated as a paper material. As an example, the entire lid part 2 has a weight of 100 g / m 2 In this case, the paper layer 2a has a thickness of 50 to 80 g / m 2 For example, the thickness of the paper layer 2a may account for 50% or more of the thickness of the lid portion 2.

[0041] The thickness of the paper layer 2a is, for example, 10 to 100 μm, and preferably 40 to 60 μm. Specifically, the thickness may be, for example, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100 μm, or may be within a range between any two of the numerical values ​​exemplified here.

[0042] The thickness of the base layer 2b is, for example, 5 to 80 μm, and preferably 10 to 40 μm. Specific examples of the thickness of the base layer 2b are 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, and 80 μm, and may be within a range between any two of the numerical values ​​exemplified here.

[0043] The thickness of the sealant layer 2c is, for example, 5 to 80 μm, and preferably 10 to 40 μm. Specific examples of the thickness of the sealant layer 2c are 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, and 80 μm, and may be within a range between any two of the numerical values ​​exemplified here.

[0044] In order to prevent the lid portion 2 from breaking, it is preferable that the Young's modulus of the base layer 2b is somewhat high. Specifically, as an example, the lower of the Young's modulus in the MD direction and the Young's modulus in the TD direction of the base layer 2b is preferably 800 MPa or more. This lower Young's modulus is, for example, 400 to 5000 MPa, and preferably 600 to 3000 MPa. Specifically, this lower Young's modulus is, for example, 400, 600, 800, 1000, 1200, 1400, 1600, 1800, 2000, 2200, 2400, 2600, 2800, 3000, 3200, 3400, 3600, 3800, 4000, 4200, 4400, 4600, 4800, 5000 MPa, and may be within a range between any two of the numerical values ​​exemplified here.

[0045] 2. Manufacturing method of microwave oven package 1 As shown in Figure 6, the microwave oven package 1 can be produced by placing the lid 2 on the flange 5 with the container 3 filled with the contents F, and then pressing a seal bar 9 against the lid 2 to form the heat-sealed part 6. The lid 2 can be prepared in advance by any manufacturing method, and may be prepared, for example, by adhering the sheets or films constituting each layer by dry lamination or the like and cutting them to the specified dimensions.

[0046] As shown in FIG. 7, the seal bar 9 is provided with a protrusion 9a having a shape corresponding to the shape of the heat-sealed portion 6. The heated protrusion 9a is pressed against the lid 2. This allows the sealant layer 2c of the lid 2 and the flange 5 to be heat-sealed. Various conditions such as the temperature and time for pressing during this welding process are set in advance so as to obtain a good seal state. The presence of the base layer 2b has the effect of preventing the lid 2 and the container 3 from being excessively welded even if the sealing temperature is high or the sealing time is long, so there is an advantage in that it is easier to adjust the conditions during welding.

[0047] As a modified example, the container 3 may be made of resin instead of paper. As another modified example, the steam exhaust section 7 may not be provided. In that case, as one example, the package 1 may be heated in a microwave oven after the lid section 2 is partially peeled off to open the inside of the container 3 to the outside air. Note that the package 1 and its modified examples may be provided for purposes other than microwave heating. EXAMPLES

[0048] 1. Preparation of Example Samples and Comparative Example Samples The example sample and the comparative sample were produced with the same structure and manufacturing method, except that the lid 2 had a base layer 2b. For both samples, a 1.5 g paper sheet and 8.5 g water were placed in a container 3 (dimensions: 110 mm x 180 mm x 30 mm) made of a paper material and shaped as shown in Fig. 6, and then the lid 2 was welded to the flange 5 of the container 3 under multiple sealing conditions (temperature and time) shown in Table 1 to obtain a package 1 having the shape shown in Figs. 1 to 5. The lid 2 was welded using a seal bar 9 shown in Figs. 6 to 7.

[0049] In the example sample, the layer configuration of the container 3 and the lid portion 2 is as follows. Container 3: Paper material layer 3a (pulp: 650 μm) / container resin layer 3b (PP: 80 μm) Lid 2: Paper layer 55μm / DL / Base material layer (Ny: 15μm) / DL / Sealant layer (PE and PP mixed resin: 30μm)

[0050] In the example sample, the three-layer structure of the lid portion 2 is bonded by dry lamination (DL), and the thickness of the DL layer is negligible. The material of the base layer 2b is nylon (manufactured by Mitsubishi Chemical Corporation, grade ST), and its melting point is 220.7°C. The sealant layer 2c is CMPS (registered trademark) manufactured by Mitsui Chemicals Tohcello, and is a mixed resin of PE and PP. The melting point of the sealant layer 2c is 153.95°C. This value is calculated based on the melting point of PP being 162.4°C and the melting point of PE being 125.0°C, assuming a mixture ratio of PP:PE = 3:1. The difference ΔT between the melting point of the base layer 2b and the melting point of the sealant layer 2c MPis 66.75° C. The base material layer 2b has a melting point which is 60° C. or more higher than that of the sealant layer 2c.

[0051] In the comparative sample, the layer configuration of the container 3 and the lid part 2 is as follows: This is the same as the example sample, except that the base layer is removed from the lid part 2. Container 3: Paper material layer 3a (pulp: 650 μm) / container resin layer 3b (PP: 80 μm) Lid 2: Paper layer 55μm / Sealant layer (PE and PP mixed resin: 30μm)

[0052] The sealing conditions shown in Table 1 are as follows: Samples No. 1 to No. 6 were subjected to a constant sealing time (1.5 seconds) with different sealing temperatures. Conversely, Samples No. 7 to No. 12 were subjected to a constant sealing temperature (150°C) with different sealing times. In Table 1, the embodiment samples are No. 1 to No. 3 and No. 7 to No. 9, and the comparative sample samples are No. 4 to No. 6 and No. 10 to No. 12.

[0053] [Table 1]

[0054] 2. Opening test After the heating test, the sample was removed from the microwave oven and left at room temperature for 1 minute, after which the lid 2 was grasped at the wide portion 5b where the steam exhaust portion 7 is provided, and the lid 2 was slowly peeled off, and the state of the lid was visually observed. The same test was performed on 12 samples, and based on the results, each sample was scored according to the following criteria, and the ease of opening was evaluated on a three-level scale.

[0055] The scoring criteria are as follows: 1: Not sealed at all. 2: There was a small amount of stickering on it. 3: The seal was good. 4: The adhesive surface turned white. 5: The lid material was torn.

[0056] Each score corresponds to the following three-level rating: ○: Good seal (score 3). △: Weak but sealed (score 2). ×: The seal was too strong or there was no seal at all (score 1, 4, 5).

[0057] First, looking at samples Nos. 1 to 6, in the examples, sample No. 3 with a high sealing temperature was also rated as ◯. However, in the comparative examples, sample No. 6 with a high sealing temperature (160°C) was rated as ×. Next, looking at samples Nos. 7 to 12, in the examples, sample No. 9 with a longer sealing time was also rated as ◯. However, in the comparative examples, sample No. 12 with a longer sealing time (2.0 seconds) was rated ×. Thus, in the examples, even if the sealing temperature was high or the sealing time was long, the lid 2 and the container 3 were not excessively welded together, and whitening of the adhesive surface or tearing of the lid material did not occur when the product was opened.

[0058] Moreover, looking at the example samples No. 1 and No. 7, even the samples with a lower sealing time (140°C) or a shorter sealing time (1.0) were rated △, which is equivalent to the comparative example. According to the configuration of the example, it was found that even though the layer configuration is increased by the presence of the base layer 2b, welding equivalent to the comparative example can be performed even if the sealing temperature is lower or the sealing time is shorter.

[0059] As described above, the embodiment has the advantage of making it easier to adjust the conditions during heat welding.

[0060] 3. Bursting strength test The seal strength was measured when the lid 2, which had been opened halfway, was pulled toward the unopened side. The seal width was 3 mm. The higher the sealing temperature and the longer the sealing time, the higher the seal strength. In order to avoid the seal strength being too weak in the case of microwave heating, the seal strength is preferably 2.0 N or more. [Explanation of symbols]

[0061] 1: Microwave packaging 2: Lid 2a:Paper layer 2b: Base material layer 2c: Sealant layer 3: Container 3a:Paper material layer 3b: Container resin layer 4: Container body 4a:Top edge 5: Flange part 5a: Inner edge 5b: Wide section 5c: Outer edge 5e: Inclined part 6: Heat welded part 6a: Part 7: Steam exhaust section 7a: Root 7b: Part 7c: area 7d: Outer edge 7e : First line segment 7f: Second line segment 7g :Bisector 7h: Part 8: Transition 9: Seal bar 9a:Protrusion 10: Test piece 10a: Part 10b: Part 11a: Jig 11b: Jig 12: Test piece 12a: Part 12b: Part A: Tip C: Intersection F:Contents S1: Line segment S2: Line segment

Claims

1. A package for storing contents in a sealed state, comprising: The packaging body includes a lid and a container, The lid portion is formed by stacking a sealant layer, a base layer, and a paper layer in this order, the sealant layer is heat welded to the container; The base layer is formed of a resin, The packaging body, wherein the base layer has a melting point higher than the melting point of the sealant layer.

2. 2. The packaging of claim 1, The packaging body, wherein the lower of the Young's modulus in the MD direction and the Young's modulus in the TD direction of the base material layer is 800 MPa or more.

3. The packaging body according to claim 1 or 2, The package is a package for microwave heating.

4. The packaging body according to claim 1 or 2, The packaging body, wherein the base layer is formed from a polyester-based resin, a polyamide-based resin, or an olefin-based resin.

5. The packaging body according to claim 1 or 2, The container is constructed by laminating a paper material layer and a container resin layer, The sealant layer is heat-sealed to the container resin layer.

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