Gusset packaging

Abstract

To provide a package capable of not only serving as tableware after opening, but also facilitating proceeding of opening and an opening size so as to be made as expected.SOLUTION: In a gusset package 1A: a boundary between a main face part 5a and a first side face part 7a is defined to be a first hem-seal part 11a; a first opening guide line 15a and a second opening guide line 15b extend onto the main face part 5a with two opening start parts 13, 13 as starting points; the first side face part 7a includes a third opening guide line 15c for merging both the opening guide lines 15a, 15b with each other; the first opening guide line 15a extends to a position where a tip thereof is closer to a second side face part 7b than the first hem-seal part 11a; the second opening guide line 15b extends to a position where a tip thereof is closer to the first hem-seal part 11a than the second side face part 7b; and both the tips of the opening guide lines 15a, 15b are directed toward on side in a longitudinal direction of the first hem-seal part.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Conventionally, cooked or semi-cooked food is contained in a packaging bag that can be stored at room temperature, low temperature, or frozen, and is heated in a microwave oven without being opened. For example, the packaging bag disclosed in Patent Document 1 has an opening aid with reduced tear strength in part of the packaging bag, and small holes for steam release are formed in the opening aid when the internal pressure increases due to heating during cooking, thereby preventing the packaging bag from bursting and allowing the food to be sufficiently steamed. The food can then be removed by tearing open the bag starting from the back seal.

[0003] Similarly, there are packaging bags for microwave ovens that are opened by tearing from the back seal, and can be used as a tray (dish) after opening. For example, the packaging bag in Patent Document 2 can be easily opened along a predetermined opening cut line, and can be used as a tray with an attractive opening shape. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5948002 [Patent Document 2] Patent No. 5527891 Summary of the Invention [Problem to be solved by the invention]

[0005] In all of the above examples, the package is opened by pinching the spine seal, starting from the spine seal, so it is desirable for the force to be transmitted evenly to both sides of the spine seal. However, there are cases where the opening deviates from the guide line on one side or the opening progresses asymmetrically, resulting in an insufficient opening. Conversely, there are cases where the opening is too wide, causing the contents to spill. Therefore, the present invention aims to provide a package that can double as tableware after opening and that allows the opening progress and opening size to be easily achieved as expected. [Means for solving the problem]

[0006] The present invention provides a gusset package formed by heat-sealing a packaging material in which a uniaxially stretched base resin layer and a heat-sealable resin layer are laminated, the gusset package comprising: a main surface portion; a first side surface portion connected to the main surface and having an inward fold line; and a second side surface portion connected to the main surface on the opposite side from the first side surface portion and also having an inward fold line, wherein the boundary between the main surface portion and the first side surface portion is a first hem-sealed portion where the portion corresponding to the fold line is a hem-sealed portion, and the first hem-sealed portion has two opening start portions which are located at different positions in the length direction, the opening start portions being located at a position closer to one side of the center portion in the length direction, or being located asymmetrically so as to sandwich the center portion in the length direction but shifted to one side with respect to the center portion, or one opening start portion being located at the center portion in the length direction and the other opening start portion being located at a position closer to one side of the center portion the first side surface portion has third opening guide lines which start at the two opening start portions and extend towards the first side surface portion respectively and join together at the first side surface portion, the first opening guide line having a tip which extends to a position closer to the second side surface portion than the first hem seal portion, and the second opening guide line having a tip which extends to a position closer to the first hem seal portion than the second side surface portion, and the tips of both the first opening guide line and the second opening guide line are directed to the opposite side from one side in the length direction of the first hem seal portion.

[0007] To open this gusset package, a user pinches the area between the two tear-initiating sections of the first hem seal and begins tearing. The tearing proceeds along the first, second, and third tearing guide lines. Once the third tearing guide line is completely torn, the pinched portion and the portion enclosed by the third tearing guide line are free to move freely away from the gusset bag body. The tearing then proceeds along the first and second tearing guide lines by twisting the bag in the direction opposite the "one side." After the tearing reaches the ends of the first and second tearing guide lines, the tearing can be continued in the direction opposite the "one side" to the desired position, resulting in a sufficient opening area. Because force is transmitted smoothly during this tearing process, the opening proceeds as expected, and the opening size is likely to be as large as expected.

[0008] The present invention also provides a gusset package formed by heat-sealing a packaging material in which a uniaxially stretched base resin layer and a heat-sealable resin layer are laminated together, the gusset package comprising a main surface portion, a first side surface portion connected to the main surface and having an inward fold line, and a second side surface portion connected to the main surface on the opposite side from the first side surface portion and also having an inward fold line, wherein the boundary between the main surface portion and the first side surface portion is a first hem-sealed portion in which the portion corresponding to the fold line is hem-sealed, and the first hem-sealed portion has two opening start portions at different positions in its length direction, the opening start portions being formed along its length. The present invention provides a gusset package in which the two opening start portions are arranged so as to sandwich a central portion in a direction, the main surface portion has a first opening guide line that starts from one of the two opening start portions and extends onto the main surface portion, and a second opening guide line that starts from the other opening start portion and extends onto the main surface portion, the first side surface portion has third opening guide lines that start from the two opening start portions and extend towards the first side surface portion respectively and join together at the first side surface portion, and the first opening guide line and second opening guide line extend towards the second side surface portion while moving away from each other on the main surface portion.

[0009] To open this gusset package, a user pinches the area between the two tear-initiating portions of the first hem seal and begins tearing. The tearing proceeds along the first, second, and third tearing guide lines. Once the third tearing guide line is completely torn, the pinched portion and the portion enclosed by the third tearing guide line are free to move freely away from the gusset bag body. The user can then move the pinched portion toward the second side surface to continue tearing along the first and second tearing guide lines. Even after the tearing reaches the ends of the first and second tearing guide lines, the user can continue to move the initially pinched portion toward the second side surface to the desired position from each of the ends toward the second side surface, thereby achieving a sufficient opening area. Because force is transmitted smoothly during this tearing process, the opening proceeds as expected, and the opening size is likely to be as large as expected.

[0010] These gusseted wrappers may have one or more of the following features:

[0011] In these gusset packages, the boundary between the main surface portion and the second side surface portion may be a second hem seal portion, where the portion corresponding to the fold edge is hem-sealed. The presence of the second hem seal portion in this portion can stop tearing at that point if the force of the tearing attempt is too strong. Furthermore, when the tear reaches the second hem seal portion, the second hem seal portion can act as a guide to continue the tearing along its length.

[0012] In these gusset packages, the third opening guide line may be located closer to the main surface than the fold line. In this case, when the gusset package is placed with the opening facing upward after opening, the width of the side surface up to the fold line can be ensured as the height from the bottom surface. This can prevent liquid from spilling, especially when the contents contain liquid, and allows the package to function adequately as tableware.

[0013] In these gusset packages, the first hem seal portion may have a hem seal width of 3 mm to 20 mm, which makes it easy to grip that portion when opening the package.

[0014] In these gusset packages, at least one of the first opening guide line, the second opening guide line, and the third opening guide line may be a score line provided deep enough not to penetrate the packaging material. Also, in these gusset packages, at least one of the first opening guide line, the second opening guide line, and the third opening guide line may be a continuous line, a broken line, a dotted line, or a combination thereof formed by laser processing. In these cases, opening along each opening guide line is facilitated.

[0015] In these gusset packages, the two opening initiation portions may be notches formed at angles that are not parallel to the first and second opening guide lines. Notches are easy to form and are useful as opening initiation portions. Furthermore, even if some misalignment occurs between the notches and the opening guide lines during formation, because the notches are formed at angles that are not parallel to each other, the adverse effect of misalignment on opening can be reduced. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a package that can double as tableware after opening, and in which the progress of opening and the size of the opening are likely to be as expected. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a perspective view of a gusset package according to a first embodiment. FIG. [Figure 2] FIG. 2 is a side view of FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along the line III-III in FIG. [Figure 4] FIG. [Figure 5] FIG. 2 is a perspective view of the gusset package of FIG. 1 when opening is completed. [Figure 6] FIG. 10 is a perspective view of a gusset package according to a second embodiment. [Figure 7] FIG. 3 is a perspective view of the gusset package of FIG. 2 when opening is completed. [Figure 8] 1(A) to 1(H) are plan views of gusset packages of various embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention relates to a so-called gusset package (hereinafter simply referred to as "package"). This package contains food, and by forming a steam vent in part of the package during microwave cooking, it is possible to prevent rupture due to internal pressure. Furthermore, after cooking, the package can be opened from the opening start part provided in the hem seal part, and a wide opening can be easily formed on the main surface of the package, making it easy to remove food and allowing the package to also be used as tableware. Preferred embodiments of the present invention will be described in detail below with reference to the drawings. Note that the same or corresponding parts in each drawing will be designated by the same reference numerals, and redundant explanations will be omitted.

[0019] First Embodiment As shown in Figures 1 to 3, packaging body 1A of this embodiment is a bag containing a sealed food item, and includes a back seal portion 3a formed by heat-sealing the back seal portion 3a in a folded configuration, and end seal portions 3b and 3c that are heat-sealed at both ends of back seal portion 3a so that they are perpendicular to back seal portion 3a. The body portion, which contains the food item, is made up of the parts other than back seal portion 3a and end seal portions 3b and 3c. Note that the food item inside is not shown in Figure 3. Figure 4 is a plan view of packaging material 100 before packaging body 1A is formed.

[0020] The side where the spine seal portion 3a is formed and the side where it is not formed form the front and back of the package 1A. In this embodiment, the side where the spine seal portion 3a is not formed is called the main surface (main surface portion) 5a, and the side where the spine seal portion 3a is formed is called the back surface 5b. The side surfaces connected to both sides of the main surface 5a and constituting the thickness of the package 1A are called the first side surface portion 7a and the second side surface portion 7b, respectively. The first side surface portion 7a and the second side surface portion 7b both have fold lines 9a, 9b that lead inward to the package 1A. As will be described later, the first side surface portion 7a is the side from which opening begins.

[0021] The boundary between the main surface 5a and the first side surface 7a is hem-sealed along the fold line to form a first hem-sealed portion 11a. Similarly, the boundary between the main surface 5a and the second side surface 7b is hem-sealed along the fold line to form a second hem-sealed portion 11b. The boundary between the back surface 5b and the first side surface 7a is hem-sealed along the fold line to form a third hem-sealed portion 11c. Similarly, the boundary between the back surface 5b and the second side surface 7b is hem-sealed along the fold line to form a fourth hem-sealed portion 11d. Two notches (opening start portions) 13, 13 are provided in the first hem-sealed portion 11a at a position closer to one side (the end seal portion 3b side) than the center in the longitudinal direction.

[0022] Of the four hem seal portions 11a, 11b, 11c, and 11d, the first hem seal portion 11a has a larger seal width than the other hem seal portions 11b, 11c, and 11d. The seal width of first hem seal portion 11a may be 3 mm to 20 mm, or may be 5 mm to 15 mm. In this way, the seal width of first hem seal portion 11a is larger than the other hem seal portions 11b, 11c, and 11d, and a certain degree of seal width is ensured, which makes it easy to form notches 13 and makes it easy to pinch first hem seal portion 11a with fingers when starting to open the package.

[0023] The packaging body 1A has, on its main surface 5a, a first opening guide line 15a that extends from the notch 13, 13 that is closer to the end of the first hem seal portion 11a in the longitudinal direction of the two notches 13, 13 onto the main surface 5a, and a second opening guide line 15b that extends from the notch 13 that is closer to the center of the first hem seal portion 11a in the longitudinal direction onto the main surface 5a.

[0024] First opening guide line 15a extends linearly to a position closer to second hem seal portion 11b than first hem seal portion 11a (a position closer to second side surface portion 7b), and gently curves near its tip, with the tip pointing toward the opposite side from the side on which notches 13, 13 are provided on first hem seal portion 11a, i.e., toward end seal portion 3c. Because the tip is gently curved, the angle between the direction of the linear extension from notch 13 toward second hem seal portion 11b and the direction of the tip is 95° to 175°.

[0025] Second opening guide line 15b extends only to a position closer to first hem seal portion 11a than second side surface portion 7b, and gently curves near its tip, with the tip pointing toward the opposite side of first hem seal portion 11a from the side where notches 13, 13 are provided, i.e., toward end seal portion 3c. Because the tip is gently curved, the angle between the direction of the linear extension from notch 13 toward second hem seal portion 11b and the direction of the tip is 95° to 135°. From the perspective of ease of guiding tearing during opening, this angle is preferably smaller than the angle of first opening guide line 15a.

[0026] It is preferable that notches 13, 13 are formed in first hem seal portion 11a at an angle that is not parallel to first opening guide line 15a and second opening guide line 15b. During manufacturing, notches 13, 13 are provided in first hem seal portion 11a at the positions of first opening guide line 15a and second opening guide line 15b after packaging material 100 (see FIG. 4) on which opening guide line 15 has been formed is formed into a bag shape to form each hem seal portion 11a, 11b, 11c, 11d. In this case, forming notches 13, 13 at an angle that is not parallel to first opening guide line 15a and second opening guide line 15b is preferable because it increases the tolerance for alignment in an apparatus for forming notches 13, 13.

[0027] The first side surface portion 7a has a third opening guide line 15c that extends from the two notches 13, 13 toward the first side surface portion 7a and merges with each other within the first side surface portion 7a. Therefore, the first opening guide line 15a, the third opening guide line 15c, and the second opening guide line 15b are continuous in this order and form a single folded line (see FIG. 4). In this embodiment, the third opening guide line 15c is provided in a U-shape in a side view so as to fit within an area closer to the main surface 5a than the fold line 9a.

[0028] Here, the packaging material 100, which is the constituent material of the package 1A, is a rectangular resin sheet composed of a laminate of resin films. Before the package 1A is formed, the packaging material 100 has a band-shaped heat-sealed portion 3 along its entire peripheral region. That is, the heat-sealed portion 3 extends around the entire periphery of the rectangle, a predetermined distance from the edge of the rectangle into the interior of the rectangle. In FIG. 4 , a pair of parallel end portions of the packaging material 100, located at both ends in the left-right direction in the figure and extending in the up-down direction in the figure, are heat-sealed together in a palm-to-palm fashion to form the spine seal portion 3a. The packaging material 100 has a single opening guide line 15 spanning the main surface 5a and the portion that will become the first side surface portion 7a. After the packaging material 100 is formed into a bag shape, notches 13, 13 are provided to divide the opening guide line 15 into a first opening guide line 15a, a second opening guide line 15b, and a third opening guide line 15c.

[0029] The laminate constituting the packaging material 100 includes at least a uniaxially stretched base resin layer and a heat-sealable resin layer. The heat-sealable resin layer is laminated as the innermost layer of the packaging body 1A. An adhesive or a printed layer for bonding the base resin layer and the heat-sealable resin layer may be provided between them. In addition, a gas barrier layer, a light-shielding layer, an ultraviolet absorbing layer, etc. may be provided.

[0030] The base resin layer is preferably a nylon film or a polyethylene terephthalate film. The thickness of the base resin layer is, for example, 10 μm to 30 μm. The uniaxially stretched direction of the uniaxially stretched film coincides with the extending direction of the back seal portion 3a of the package 1A.

[0031] Polyolefin resins such as polyethylene resin and polypropylene resin are commonly used as the heat-sealable resin layer (sealant). Among polyethylene resins, low-density polyethylene and linear low-density polyethylene are preferred. In the case of the package 1A of this embodiment, linear low-density polyethylene copolymerized with C4 (butene-1) as a comonomer using a Ziegler-Natta catalyst is particularly preferred. This polyethylene is easy to tear by hand, and when heated in a microwave oven, the opening guide wire partially breaks and opens, easily forming a steam vent hole that functions as a steam release port. The heat-sealable resin layer may be formed by melting the resin and extruding it onto the base resin layer, or by laminating a film formed thereon.

[0032] In this embodiment, the heat-sealable resin layer preferably has a Young's modulus (tensile modulus) of 0.2 gigapascals (GPa) or more, as measured in accordance with JIS K 7127, which is expressed as the slope of the straight line in the elastic deformation range of a stress-strain curve. This Young's modulus may be 0.3 gigapascals or more, or may be 0.4 gigapascals or more. If the Young's modulus is within this range, the heat-sealable resin layer is less likely to stretch, and steam vents are more likely to form when heated in a microwave oven.

[0033] The thickness of the heat-sealable resin layer may be, for example, 10 μm to 50 μm, or 20 μm to 40 μm.

[0034] Furthermore, the laminate preferably has a Young's modulus (tensile modulus), which is expressed as the slope of the straight line in the elastic deformation range of a stress-strain curve, of 0.45 gigapascals (GPa) or more when measured in accordance with JIS K7127. In this measurement, a sample having an opening guide line formed thereon is prepared, and this sample is used as the measurement subject, and is stretched at two locations across the opening guide line (two locations in a direction perpendicular to the direction of extension of the cut line described below). If the Young's modulus value is 0.45 gigapascals or more, the elongation of the laminate due to internal pressure when heated in a microwave oven (to an extent sufficient to withstand rupture of the package 1A) and the formation of the steam vent hole are easily balanced.

[0035] The opening guide line 15 is a score line provided from the base resin layer side to a depth that does not penetrate the packaging material 100. The depth of the cut can be such that the relevant portion can be made more fragile than the other portions and does not penetrate the packaging material 100 (so-called "half cut"). For example, the cut line may be formed so that a layer other than the heat-sealable resin layer is cut. Such a score line can be formed by a method using a blade such as a die cutter or rotary die cutter, or by a method using a laser processing machine such as a carbon dioxide laser. When using laser processing, the material is melted based on the line width of the laser, thereby forming a wide score line. The width of the score line formed by melting the material is, for example, 50 to 300 μm, preferably 100 to 250 μm. The length of the score line may be 10 mm to 100 mm, or 30 mm to 70 mm.

[0036] The packaging 1A can heat and steam food contained therein by microwave cooking. Normally, when a sealed packaging is heated, the internal pressure increases and the packaging bursts. However, in the packaging 1A of this embodiment, when the internal pressure increases and the packaging expands, tension is applied to the entire body, and at least one of the first opening guide line 15a, the second opening guide line 15b, and the third opening guide line 15c, which are weak against tensile stress, partially breaks, forming a steam vent. Steam is released from the steam vent, reducing the internal pressure and preventing the packaging 1A from bursting, while allowing the food to be steamed by the steam that fills the interior.

[0037] In such microwave cooking, if the Young's modulus of the heat-sealable resin layer of the packaging material constituting the package 1A is 0.2 gigapascals (GPa) or more, the steam vent hole is likely to be formed appropriately, particularly when a highly hygroscopic film such as a nylon film is used as the uniaxially stretched film.

[0038] To open the package 1A after microwave cooking, pinch the area between the two notches 13, 13 in the first hem seal portion 11a, make a slit at the notches 13, 13, and begin tearing. The tearing proceeds along the opening guide lines 15a, 15b, and 15c. Once the third opening guide line 15c is completely torn, the pinched portion and the portion enclosed by the third opening guide line 15c become free to move away from the main body of the package 1A. Then, by twisting the pinched portion toward the end seal portion 3c, the opening can proceed along the first opening guide line 15a and the second opening guide line 15b. After the tearing reaches the ends of the first opening guide line 15a and the second opening guide line 15b, the tearing can continue to the desired position, as shown in FIG. 5. At this time, the direction of the tip of the first opening guide line 15a and the second opening guide line 15b curves from the initial direction of travel and changes to the direction toward the end seal portion 3c, so the tear is guided toward the end seal portion 3c. At this time, the uniaxial stretching direction of the uniaxially stretched film constituting the packaging material coincides with the extending direction of the back seal portion 3a, so the tear easily progresses toward the end seal portion 3c.

[0039] When the package 1A is opened, the above-described opening process provides a sufficient opening area. Because force is transmitted smoothly during this opening process, the opening tends to proceed as expected, and the opening tends to have the expected size. Even if the force of the opening or tearing is too strong, the second hem seal portion 11b can stop the tearing. Furthermore, when the tear reaches the second hem seal portion 11b, the second hem seal portion 11b can act as a guide to further tearing along its length.

[0040] When package 1A is opened, a sufficient opening area is provided, making it easy to remove the contents (food 17). After opening, package 1A can also serve as tableware, eliminating the need to transfer food 17 to another tableware. Furthermore, because third opening guide line 15c is located closer to main surface 5a than fold line 9a, when package 1A is placed with the opening facing upward after opening, the width of first side surface 7a up to fold line 9a can be ensured as a height from the bottom surface. This prevents liquid spillage, particularly when the contents contain liquid, and allows package 1A to fully function as tableware.

[0041] The first embodiment of the present invention has been described above, but various modifications can be made to this first embodiment. For example, in the above embodiment, the notches 13, 13 are both positioned closer to the end seal portion 3b. However, the notch closer to the center in the direction of extension of the first hem seal portion 11a may be positioned in the center or closer to the end seal portion 3c. That is, the notches 13, 13 may be positioned so that one is located in the center of the length and the other is located closer to one side of the center. Alternatively, the notches 13, 13 may be positioned asymmetrically so that they sandwich the center of the length of the first hem seal portion 11a but are offset to one side of the center. In this case, the positions of the opening guide lines 15a, 15b, 15c are also changed.

[0042] In addition, in the above embodiment, in addition to the first hem seal portion 11a, the second hem seal portion 11b, the third hem seal portion 11c, and the fourth hem seal portion 11d are also provided, but it is also possible to provide an embodiment in which at least one of the second hem seal portion 11b, the third hem seal portion 11c, and the fourth hem seal portion 11d is not provided.

[0043] Second Embodiment A second embodiment of the present invention will now be described. Package 1B of the second embodiment shown in Figure 6 differs from package 1A of the first embodiment in the positions and shapes of notches 13, 13 and opening guide lines 15a, 15b, 15c, and the uniaxial stretching direction of the uniaxially stretched film that constitutes the packaging material.

[0044] In package 1B, notches 13, 13 are provided on either side of the longitudinal center of first hem seal portion 11a. First opening guide line 15a and second opening guide line 15b, which extend from each of notches 13, 13 onto main surface 5a, extend toward second hem seal portion 11b while moving away from each other on main surface 5a. More specifically, first opening guide line 15a extends toward end seal portion 3b and second hem seal portion 11b, while second opening guide line 15b extends toward end seal portion 3c and second hem seal portion 11b. When viewed from the notch 13, 13 side, first opening guide line 15a and second opening guide line 15b have a diverging shape. The first opening guide line 15a and the second opening guide line 15b have the same length, and the positions of their tips remain closer to the first hem seal portion 11a side than to the second hem seal portion 11b side.

[0045] In the packaging body 1B, the uniaxially stretched direction of the uniaxially stretched film constituting the packaging material coincides with the direction in which the end seal portions 3b and 3c extend, i.e., is perpendicular to the stretching direction in the packaging body 1A of the first embodiment.

[0046] When the package 1B is opened, the first opening guide line 15a and the second opening guide line 15b are torn simultaneously, as shown in Figure 7. After the tear reaches both ends, the subsequent opening proceeds in a straight line toward the second hem seal portion 11b.

[0047] While the first embodiment of the present invention has been described above, various modifications can be made to this first embodiment. For example, in the above embodiment, the shape of the opening guide line is configured as a continuous line consisting of three parts, but it may be not only a continuous line, but also a dashed line, a dotted line, or a combination thereof. [Example]

[0048] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0049] Example 1 A packaging material (25 cm x 38 cm) was used, consisting of a uniaxially stretched nylon film (trade name "Uniathlon TB-1000", manufactured by Idemitsu Unitech Co., Ltd., thickness 15 μm) as the base resin layer and a linear low-density polyethylene film (trade name "KF101", manufactured by Sky Films Co., Ltd., thickness 40 μm, Young's modulus 0.40 GPa) as the heat-sealable resin layer. A carbon dioxide laser (output 25 W, scan speed 800 mm / sec) was irradiated from the uniaxially stretched nylon film side of this packaging material to form an opening guide line in the shape shown in Figure 8(A) that did not penetrate the heat-sealable resin layer. The stretching direction of the nylon film was aligned with the extension direction of the spine seal.

[0050] The periphery of the packaging material (excluding the edge seal on one side) was heat-sealed, and then a total of four folds were hem-sealed, between the main surface and the side surface, and between the back surface and the side surface. The hem seal width in the area corresponding to the first hem seal was 15 mm, and the hem seal width in the other areas was 5 mm. 20 mL of water was placed inside, and the remaining edge seals were heat-sealed to create a package with the external shape shown in Figure 1. A notch was made in the area corresponding to the first hem seal width. This package was heated in a microwave oven at 600 W for 3 minutes, and then an opening test was performed.

[0051] <Example 2> The same procedure as in Example 1 was carried out except that the width of the first hem seal portion was made the same as the width of the other hem seal portions (FIG. 8(B)).

[0052] Example 3 The same procedure as in Example 1 was carried out except that the shape of the opening guide line was changed as shown in Figure 8(C) and the stretching direction of the nylon film was adjusted to be perpendicular to the direction in which the back seal portion extended.

[0053] Example 4 The same procedure as in Example 1 was carried out except that the opening guide line on the side surface was adjusted to extend beyond the fold line on the side surface toward the bottom surface (FIG. 8(D)).

[0054] <Comparative Example 1> The same procedure as in Example 1 was carried out except that no notch was provided (FIG. 8(E)).

[0055] <Comparative Example 2> The procedure was the same as in Example 1 except that a second opening guide line was provided (FIG. 8(F)).

[0056] <Comparative Example 3> The same procedure as in Example 1 was carried out except that hem sealing was not performed (FIG. 8(G)).

[0057] <Comparative Example 4> The same procedure as in Example 1 was carried out except that the first hem seal portion was not provided (FIG. 8(H)).

[0058] The evaluation methods for each test were as follows: "Openability" was evaluated separately at the start of opening and the subsequent opening guidance. Regarding the start of opening, if the opening started from the notch, it was marked as "◎", if it started very well, it was marked as "○", and if it could not be opened properly, it was marked as "×". Regarding the opening guidance, if the package was opened properly along the opening guidance line, it was marked as "○", and if it could not be opened along the opening guidance line, it was marked as "×". For "opening width," packages that could be opened over 50% or more of the main surface were marked with an "O"; packages that could not be opened or that could not be opened were marked with an "X." - For "prevention of spillage of contents," a box was rated as "○" if the enclosed water did not spill when opened, and "×" if it did spill.

[0059] The results are shown in Table 1. In Table 1, the surface that will be on the top when opened is called the "top surface," and the surface that will be on the bottom is called the "bottom surface." The first hem seal portion is called the "hem seal on the notch side." In addition, in the "width of the hem seal on the notch side" section, a hem seal width of 15 mm at the part corresponding to the first hem seal portion was rated "large," and a hem seal width of 5 mm was rated "small."

[0060] The test results showed that the packages of Examples 1 to 4 were all good in terms of opening initiation, opening guidance, and opening width. Example 4 had a deep opening on the side, which made it easy for water to spill out. Comparative Examples 1 to 4 were inadequate in terms of either opening initiation or opening width.

[0061] [Table 1] [Industrial Applicability]

[0062] The present invention can be used in packaging for microwave cooking. [Explanation of symbols]

[0063] 1A, 1B...gusset packaging body, 3...portion to be heat sealed, 3a...back seal portion, 3b, 3c...end seal portion, 5a...main surface (main surface portion), 5b...rear surface, 7a...first side portion, 7b...second side portion, 9a, 9b...fold line, 11a...first hem seal portion, 11b...second hem seal portion, 11c...third hem seal portion, 11d...fourth hem seal portion, 13...notch (opening start portion), 15...opening guide line, 15a...first opening guide line, 15b...second opening guide line, 15c...third opening guide line, 17...food, 100...packaging material.

Claims

1. A packaging material in which a uniaxially stretched base resin layer and a heat-sealable resin layer are laminated is heat-sealed to form the packaging material, A gusset package comprising: a main surface portion; a first side surface portion connected to the main surface and having an inward fold line; and a second side surface portion connected to the main surface on the opposite side from the first side surface portion and having an inward fold line, The boundary between the main surface portion and the first side surface portion is a first hem-sealed portion in which the portion corresponding to the fold edge is hem-sealed, The first hem seal portion has two opening start portions that are located at different positions in the length direction, and are provided at a position closer to one side of the center portion in the length direction, or are provided at asymmetric positions so as to sandwich the center portion in the length direction but shift to one side with respect to the center portion, or one is provided at the center portion in the length direction and the other is provided at a position closer to one side of the center portion, The main surface portion has a first opening guide line that extends onto the main surface portion from an opening start portion of the two opening start portions that is closer to the end in the length direction of the first hem seal portion as a starting point, and a second opening guide line that extends onto the main surface portion from an opening start portion of the first hem seal portion that is closer to the center in the length direction, The first side surface portion has third opening guide lines that extend from the two opening start portions toward the first side surface portion and join together at the first side surface portion, a tip of the first opening guide line extends to a position closer to the second side surface portion than the first hem seal portion; a tip of the second opening guide line extends to a position closer to the first hem seal portion than the second side portion; A gusset package, wherein the first opening guide line and the second opening guide line both have their tips pointing toward the opposite side from the one side in the longitudinal direction of the first hem seal portion.

2. A packaging material in which a uniaxially stretched base resin layer and a heat-sealable resin layer are laminated is heat-sealed to form the packaging material, A gusset package comprising: a main surface portion; a first side surface portion connected to the main surface and having an inward fold line; and a second side surface portion connected to the main surface on the opposite side from the first side surface portion and having an inward fold line, The boundary between the main surface portion and the first side surface portion is a first hem-sealed portion in which the portion corresponding to the fold edge is hem-sealed, The first hem seal portion has two opening start portions at different positions in the length direction thereof, the opening start portions being provided on either side of a central portion in the length direction thereof, The main surface portion has a first opening guide line that starts from one of the two opening start portions and extends onto the main surface portion, and a second opening guide line that starts from the other opening start portion and extends onto the main surface portion, The first side surface portion has third opening guide lines that extend from the two opening start portions toward the first side surface portion and join together at the first side surface portion, A gusset package, wherein the first opening guide line and the second opening guide line extend toward the second side surface portion while moving away from each other on the main surface portion.

3. 3. The gusset package according to claim 1, wherein the boundary between the main surface portion and the second side surface portion is a second hem-sealed portion, the portion of which corresponds to the fold line.

4. The gusset package according to claim 1 or 2, wherein the third opening guide line is provided so as to be located closer to the main surface portion than the fold line.

5. 3. The gusset packaging according to claim 1, wherein the first hem seal portion has a hem seal width of 3 mm to 20 mm.

6. 3. A gusset packaging body according to claim 1, wherein at least one of the first opening guide line, the second opening guide line, and the third opening guide line is a score line provided to a depth that does not penetrate the packaging material.

7. 3. The gusset packaging body according to claim 1, wherein at least one of the first opening guide line, the second opening guide line, and the third opening guide line is a continuous line, a broken line, a dotted line, or a combination thereof formed by laser processing.

8. 3. The gusset package according to claim 1, wherein the two opening initiation portions are notches formed at an angle that is not parallel to the first opening guide line and the second opening guide line.

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