Heat-treated packaging bags and articles filled with contents therein
The packaging bag design with a heat-generating ink layer overlapping the seal by 15 mm or more addresses issues of scorching and rupture by allowing controlled steam release, maintaining bag integrity during microwave heating.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- SUN A KAKEN
- Filing Date
- 2024-11-20
- Publication Date
- 2026-06-01
AI Technical Summary
Existing heat-treated packaging bags suffer from scorching, perforation, or rupture at the opening during microwave heating due to inadequate control of steam release.
A heat-treated packaging bag design featuring a base material with a sealant layer and a heat-generating ink layer between the substrate and sealant, where the ink layer overlaps the seal by 15 mm or more, allowing steam to pass through by sealant retraction upon microwave irradiation.
Prevents scorching and rupture by enabling controlled steam release through sealant layer retraction, ensuring the bag remains intact during microwave heating.
Smart Images
Figure 2026089167000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a heat treatment packaging bag to be heat-treated in a microwave oven and an article filled with contents therein.
Background Art
[0002] Conventionally, heat treatment packaging bags for heat-treating objects to be heated (for example, frozen foods for microwave ovens) are known. Such heat treatment packaging bags can heat-treat an object to be heated (for example, frozen food) contained therein in a sealed state using a microwave oven or the like, and when the internal pressure rises due to heating, a predetermined position opens to release the pressure, thereby preventing the heat treatment packaging bag from bursting. At this time, it is important to control the opening of the heat treatment packaging bag at a desired position.
[0003] Patent Document 1 describes a microwave heat-generating packaging film including a base material and a coating layer provided on at least one of the base materials and containing a microwave heat-generating ink composition, wherein the microwave heat-generating ink composition contains a conductive organic compound and a resin. By using this microwave heat-generating packaging film, it is said that heat is generated by irradiation with microwaves and an opening can be easily formed.
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0005] However, when heat-treated packaging bags were manufactured using the microwave heating packaging film described in Patent Document 1, problems arose such as scorching or perforation at the opening, or the heat-treated packaging bags rupturing starting from the opening. To solve this problem, it is ideal that the heat generated in the coated layer by microwave irradiation softens the sealant layer, inducing seal retraction and allowing steam to pass through.
[0006] Therefore, the present invention aims to provide a heat-treated packaging bag that allows steam to pass through by the sealant layer retracting due to microwave irradiation, and an article filled therewith. [Means for solving the problem]
[0007] The present invention comprises a sheet member having a base material and a sealant layer laminated on the surface of the base material. The back-attached portion is formed by welding the sealant layer on both side edges of the sheet member in a gable shape, The sealant layer on the upper edge of the tubular sheet member is welded in a planar manner to form an upper edge seal portion. A pillow-type heat-treated packaging bag having, A heat-generating ink layer that generates heat with microwaves is formed between the substrate and the sealant layer in the central part of the upper edge sealing portion. The heat-generating ink layer overlaps the inner boundary line of the upper edge sealing portion by 15 mm or more in a continuous manner. This is a heat-treated packaging bag.
[0008] The present invention comprises a sheet member having a base material and a sealant layer laminated on the surface of the base material. With the two aforementioned sheet members stacked on top of each other, Side edge seal portions formed by welding the sealant layer on both side edges of the sheet member in a planar manner, An upper edge seal portion formed by welding the sealant layer on the upper edge of the sheet member in a planar manner. A three-sided seal type heat-treated packaging bag having, A heat-generating ink layer that generates heat in microwaves is formed between the substrate and the sealant layer in the central part of the upper edge seal portion or the side edge seal portion. The heat-generating ink layer overlaps the inner boundary line of the upper edge seal portion or the side edge seal portion by 15 mm or more in a continuous manner. This is a heat-treated packaging bag.
[0009] Furthermore, the present invention relates to an article comprising the aforementioned heat-treated packaging bag and contents sealed inside the heat-treated packaging bag. [Effects of the Invention]
[0010] According to the present invention, it is possible to provide a heat-treated packaging bag that allows steam to pass through by the sealant layer retracting due to microwave irradiation, and an article filled therewith. [Brief explanation of the drawing]
[0011] [Figure 1] This is a schematic plan view showing an example of the configuration of a pillow-type heat-treated packaging bag according to the present invention. [Figure 2] This is a schematic enlarged cross-sectional view showing an example of the configuration of the upper edge seal portion of a pillow-type heat-treated packaging bag according to the present invention. [Figure 3] This is a schematic plan view showing an example of the configuration of an article in which contents are filled into a pillow-type heat-treated packaging bag according to the present invention. [Figure 4] This is a schematic enlarged plan view showing embodiments of the heat-generating ink layer formation region in a pillow-type heat-treated packaging bag according to the present invention, where (a) shows an embodiment in which the heat-generating ink layer is formed in a rectangular region in plan view, (b) shows an embodiment in which the heat-generating ink layer is formed in a trapezoidal region in plan view, and (c) shows an embodiment in which the heat-generating ink layer is formed in an inverted trapezoidal region in plan view. [Figure 5] This is a schematic enlarged longitudinal cross-sectional view illustrating the state in which steam passes through the inside and outside of a heat-treated packaging bag when an article filled with contents in a heat-treated packaging bag according to the present invention is heated in a microwave oven, (a) showing the state before heat treatment, (b) showing the state during heat treatment, and (c) showing the state after steam has passed through the inside and outside of the heat-treated packaging bag. [Figure 6] It is a schematic enlarged plan view showing the formation region of the heat - generating ink layer formed on the pillow - type heat - treated packaging bag manufactured in the comparative example. (a) shows the heat - treated packaging bag manufactured in Comparative Example 2, and (b) shows the heat - treated packaging bag manufactured in Comparative Example 3. [Figure 7] It is a schematic plan view showing a configuration example of the three - side - bag - type heat - treated packaging bag according to the present invention. [Figure 8] It is a schematic plan view showing a configuration example of the three - side - bag - type heat - treated packaging bag according to the present invention. [Figure 9] It is a schematic enlarged plan view showing a configuration example of the side - edge seal portion of the three - side - bag - type heat - treated packaging bag according to the present invention.
Embodiments for Carrying out the Invention
[0012] An embodiment of the present invention will be described while referring to the drawings. FIG. 1 is a schematic plan view showing the configuration of the pillow - type heat - treated packaging bag 1 according to the present invention. FIG. 2 is a schematic enlarged cross - sectional view showing the configuration of the upper - edge seal portion 3 of the pillow - type heat - treated packaging bag 1 according to the present invention. The heat - treated packaging bag 1 according to the present invention is suitable for use when heat - treating the contents 21 by a microwave oven, and is more suitable for use when heat - treating food ingredients. FIG. 3 is a schematic plan view showing the configuration of the article 20 filled with the contents 21 in the pillow - type heat - treated packaging bag 1 according to the present invention. FIG. 4 is a schematic enlarged plan view showing an embodiment of the formation region of the heat - generating ink layer 13 in the pillow - type heat - treated packaging bag 1 according to the present invention. FIG. 5 is a schematic enlarged longitudinal cross - sectional view for explaining the state where steam passes through both the inside and outside of the heat - treated packaging bag 1 when the article 20 filled with the contents 21 in the heat - treated packaging bag 1 according to the present invention is heat - treated in a microwave oven.
[0013] The heat treatment packaging bag 1 according to the present invention is a pillow-shaped heat treatment packaging bag, as shown in FIGS. 1 to 2, and is composed of a sheet member 10 having a base material 11 and a sealant layer 12 laminated on the surface of the base material 11. The back sticking portion 2 is formed by welding the sealant layers 12 on both side edges of the sheet member 10 in a clasped shape, and the upper edge seal portion 3 is formed by welding the sealant layer 12 on the upper edge portion of the sheet member 10, which has become cylindrical, in a planar shape. Note that the lower part of the heat treatment packaging bag 1 is in an open state to enable filling of the contents 21.
[0014] The article 20 according to the present invention, as shown in FIG. 3, has the above-mentioned heat treatment packaging bag 1 and the contents 21 sealed inside the heat treatment packaging bag 1. Since the lower part of the heat treatment packaging bag 1 is open as described above, the contents 21 can be filled from the lower part of the heat treatment packaging bag 1, and the lower edge seal portion 4 can be formed by welding the sealant layer 12 on the lower edge portion of the sheet member 10 in a planar shape, thereby sealing the contents 21 inside the heat treatment packaging bag 1. As the contents 21, food materials to be heat-treated in a microwave oven are preferable, and in this case, the article 20 becomes a food package product.
[0015] Considering heat-treating the contents 21 by a microwave oven, the sheet member 10 is preferably formed of a plastic material having heat resistance to microwave heating. Specific examples of such plastic materials include polyolefins such as polyethylene and polypropylene; halogenated polyolefins such as polyvinylidene chloride and polyvinylidene fluoride; polyvinyl alcohol; polyamides such as nylon 6, nylon 6,6, and polymetaxylylene adipamide; polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate; polyacrylate esters such as poly(meth)acrylic acid methyl, poly(meth)acrylic acid ethyl, and poly(meth)acrylic acid butyl; and copolymers of monomers forming these. Note that “(meth)acrylic” means methacrylic or acrylic.
[0016] Specific examples of polyethylene include linear low-density polyethylene, high-pressure low-density polyethylene, high-density polyethylene, and metallocene polyethylene. Specific examples of polypropylene include propylene homopolymers and random or block copolymers of propylene with ethylene or 1-butene.
[0017] The sheet member 10 comprises a base material 11 and a sealant layer 12 laminated on the surface of the base material 11. The sheet member 10 may have other layers between the base material 11 and the sealant layer 12, and / or outside the base material 11. Specifically, as the sheet member 10, a laminated film (e.g., Ny#15 / LLDPE#60) can be used, which is made by bonding a polyamide film as the base material 11 and a linear low-density polyethylene film as the sealant layer 12 using an adhesive. Alternatively, the sheet member 10 may be a gas barrier composite film to which an inorganic oxide thin film such as aluminum oxide or silicon oxide is applied. This composite film can be obtained by heating and vaporizing aluminum oxide or silicon oxide, either individually or as a mixture, under vacuum and depositing it onto the surface of the film.
[0018] The width of the back seal portion 2 is preferably 3 to 30 mm, more preferably 5 to 20 mm, and even more preferably 7 to 15 mm. The back seal portion 2 may be fully sealed at 25°C or may be easily opened. If the back seal portion 2 is easily opened, the seal strength at 25°C is preferably 1 to 50 N / 15 mm, and more preferably 4 to 30 N / 15 mm. The seal strength at 25°C is the value measured at 25°C in accordance with JIS Z0238 "Test method for sealed flexible packaging bags" (the same applies hereinafter).
[0019] The width of the upper edge seal portion 3 is preferably 3 to 30 mm, more preferably 5 to 20 mm, and even more preferably 7 to 15 mm. The upper edge seal portion 3 may be completely sealed at 25°C or may be easily opened. However, the area of the upper edge seal portion 3 in which seal recession occurs due to the heat generated by the heat-generating ink layer 13 described later is preferably easily opened at 25°C. When the upper edge seal portion 3 is easily opened, the seal strength at 25°C is preferably 1 to 50 N / 15 mm, and more preferably 4 to 30 N / 15 mm.
[0020] The width of the lower edge seal portion 4 is preferably 3 to 30 mm, more preferably 5 to 20 mm, and even more preferably 7 to 15 mm. The lower edge seal portion 4 may be a complete seal at 25°C or may be easily opened. If the lower edge seal portion 4 is easily opened, the seal strength at 25°C is preferably 1 to 50 N / 15 mm, and more preferably 4 to 30 N / 15 mm.
[0021] As shown in Figures 1 to 4, the heat-treated packaging bag 1 according to the present invention has a heat-generating ink layer 13 formed between the base material 11 and the sealant layer 12 in the central part of the upper edge seal portion 3, which is heated by microwaves. Furthermore, the heat-generating ink layer 13 overlaps with the internal boundary line 3a of the upper edge seal portion 3 for 15 mm or more. That is, as shown in Figure 4, the heat-generating ink layer 13 straddles the center line C of the upper edge seal portion 3, and the length L1 that continuously overlaps with the internal boundary line 3a of the upper edge seal portion 3 is 15 mm or more. With such a heat-treated packaging bag 1, when heated in a microwave oven, the heat-generating ink layer 13 formed between the base material 11 and the sealant layer 12 in the central part of the upper edge seal portion 3 is heated by microwave irradiation, and the sealant layer 12 retracts, allowing steam to pass through.
[0022] The state in which the heat-treated packaging bag 1 is permeated will be explained in more detail using Figure 5. First, the article 20 filled with contents 21 in the heat-treated packaging bag 1 is placed in the microwave oven (Figure 5(a)). Next, when the heating process is started in the microwave oven, the heat-generating ink layer 13 formed between the base material 11 and the sealant layer 12 of the upper edge seal portion 3 is heated by microwave irradiation, and the heating region H near the heat-generating ink layer 13 is heated (Figure 5(b)). As a result, the sealant layer 12 in the heating region H softens, causing the seal of the sealant layer 12 to retract, and finally, steam passes through the inside and outside of the heat-treated packaging bag 1 (Figure 5(c)).
[0023] Furthermore, the central part of the upper edge seal portion 3 is the area where the most force is applied when the heat-treated packaging bag 1 expands during microwave heating. By forming the heat-generating ink layer 13 in this area, selective seal retraction can be caused at this location. If the heat-generating ink layer 13 is formed in an area other than the central part of the upper edge seal portion 3 (for example, the central part of the back seal portion 2), the heat-treated packaging bag 1 may rupture from another location (for example, the central part of the upper edge seal portion 3). Also, if the heat-generating ink layer 13 is formed in the back seal portion 2, the heat-treated packaging bag 1 must be positioned with the back seal portion 2 facing upwards when heating in a microwave oven. However, if the heat-generating ink layer 13 is formed in the upper edge seal portion 3, the heat-treated packaging bag 1 can be positioned with the back seal portion 2 facing upwards or downwards.
[0024] Furthermore, it is considered that the sealant layer 12 needs to soften over a relatively wide area for seal retraction to occur. That is, if the length L1 over which the heat-generating ink layer 13 continuously overlaps with the internal boundary line 3a of the upper edge seal portion 3 is less than 15 mm, the heating region H heated by the heat generated by the heat-generating ink layer 13 is narrow, so seal retraction of the sealant layer 12 does not occur, and the risk of the heat-treated packaging bag 1 rupturing starting from the sealant layer 12 softened only in the narrow heating region H increases. The length L1 over which the heat-generating ink layer 13 continuously overlaps with the internal boundary line 3a of the upper edge seal portion 3 is preferably 20 to 100 mm, and more preferably 20 to 70 mm. Note that the heat-generating ink layer 13 may be in contact with the internal boundary line 3a of the upper edge seal portion 3, or, as shown in the embodiment in Figure 4, it may extend beyond the internal boundary line 3a of the upper edge seal portion 3 to the inside of the heat-treated packaging bag 1.
[0025] A sheet member 10 having a heat-generating ink layer 13 can be manufactured, for example, by applying or printing a microwave heat-generating ink composition, such as that described in Patent Document 1, onto a film that will serve as a base material 11 to form the heat-generating ink layer 13, and then laminating a sealant layer 12 via an adhesive. Regarding the heat-generating characteristics of the heat-generating ink layer 13, it is preferable that the temperature of the heat-generating ink layer 13 reaches 120-220°C, and more preferably 150-200°C, when irradiated with microwaves at 600W for 2 minutes in a microwave oven. If the temperature of the heat-generating ink layer 13 is 120°C or higher, vapor leakage due to seal settling is more likely to occur, and if the temperature of the heat-generating ink layer 13 is 220°C or lower, hole formation due to heat generation can be suppressed. The heat-generating characteristics of the heat-generating ink layer 13 can be adjusted by the type and amount of the microwave heat-generating ink composition forming the heat-generating ink layer 13, and by whether the heat-generating ink layer 13 is formed on only one side of the sheet member 10 that forms the central part of the upper edge seal portion 3, or on both sides.
[0026] The region where the heat-generating ink layer 13 is formed is preferably a rectangle in plan view (viewed from the front side in Figure 1). Figure 4(a) shows an embodiment in which the heat-generating ink layer 13 is formed in a rectangular region in plan view, Figure 4(b) shows an embodiment in which the heat-generating ink layer 13 is formed in a trapezoidal region in plan view, and Figure 4(c) shows an embodiment in which the heat-generating ink layer 13 is formed in an inverted trapezoidal region in plan view. In addition to the above, the region where the heat-generating ink layer 13 is formed may be a square, parallelogram, rhombus, or other quadrilateral, as well as other polygons or circles / ellipses.
[0027] The heat-generating ink layer 13 may be exposed to the outer end face 3b of the upper edge seal portion 3, but it is preferable that it be formed inside the outer end face 3b of the upper edge seal portion 3 and not exposed to the outer end face 3b of the upper edge seal portion 3, as shown in the embodiment in Figure 4. If the heat-generating ink layer 13 is exposed to the outer end face 3b of the upper edge seal portion 3, the upper edge seal portion 3 may peel off due to the influence of moisture from the outside, but if it is not exposed to the outer end face 3b of the upper edge seal portion 3, unintended peeling of the upper edge seal portion 3 can be reduced. The distance W0 from the outer end face 3b of the upper edge seal portion 3 to the end of the heat-generating ink layer 13 is preferably 1 to 5 mm, and more preferably 2 to 4 mm.
[0028] By using such a heat-treated packaging bag 1, when an item 20 filled with contents 21 in the heat-treated packaging bag 1 is heated in a microwave oven, the heat-generating ink layer 13 formed between the base material 11 and the sealant layer 12 in the center of the upper edge seal portion 3 is heated by microwave irradiation, causing the sealant layer 12 to retract and allowing steam to pass through. Therefore, it is possible to suppress scorching or punctures at the opening, and prevent the heat-treated packaging bag 1 from rupturing with the opening as the starting point.
[0029] The pillow-type heat-treated packaging bag 1 according to the present invention has been described above, but the heat-treated packaging bag 1 according to the present invention may also be a three-sided bag type. Figures 7-8 are schematic plan views showing the configuration of the three-sided bag type heat-treated packaging bag 1 according to the present invention. Figure 9 is a schematic enlarged plan view showing an embodiment of the heat-generating ink layer 13 formation area in the three-sided bag type heat-treated packaging bag 1 according to the present invention. Hereinafter, only the parts that differ from the embodiment of the pillow-type heat-treated packaging bag 1 according to the present invention will be described for the embodiment of the three-sided bag type heat-treated packaging bag 1 according to the present invention, and the other parts will be the same as the embodiment of the pillow-type heat-treated packaging bag 1 according to the present invention.
[0030] As shown in Figures 7-8, the heat-treated packaging bag 1 according to the present invention is a three-sided bag type heat-treated packaging bag 1, comprising a sheet member 10 having a base material 11 and a sealant layer 12 laminated on the surface of the base material 11. With two sheet members 10 stacked together, the side edge seal portion 5 is formed by welding the sealant layers 12 on both side edges of the sheet member 10 in a planar manner, and the upper edge seal portion 3 is formed by welding the sealant layer 12 on the upper edge of the sheet member 10 in a planar manner. The lower part of the heat-treated packaging bag 1 is left open to allow filling of contents 21.
[0031] The article 20 according to the present invention comprises the heat-treated packaging bag 1 described above and contents 21 sealed inside the heat-treated packaging bag 1. As described above, since the bottom of the heat-treated packaging bag 1 is open, the contents 21 can be filled from the bottom of the heat-treated packaging bag 1, and the sealant layer 12 on the lower edge of the sheet member 10 can be welded in a planar manner to form a lower edge seal portion 4, thereby sealing the contents 21 inside the four-sided bag-type heat-treated packaging bag 1. The contents 21 are preferably food items that are heated in a microwave oven, and in this case, the article 20 is a food package product.
[0032] The width of the side edge seal portion 5 is preferably 3 to 30 mm, more preferably 5 to 20 mm, and even more preferably 7 to 15 mm. The side edge seal portion 5 may be completely sealed at 25°C or may be easily opened. However, the area of the side edge seal portion 5 in which seal recession occurs due to the heat generated by the heat-generating ink layer 13 is preferably easily opened at 25°C. When the side edge seal portion 5 is easily opened, the seal strength at 25°C is preferably 1 to 50 N / 15 mm, and more preferably 4 to 30 N / 15 mm.
[0033] As shown in Figures 7-8, the heat-treated packaging bag 1 according to the present invention has a heat-generating ink layer 13 formed between the base material 11 and the sealant layer 12 in the central part of the upper edge seal portion 3 or the side edge seal portion 5, which generates heat when exposed to microwaves. Furthermore, the heat-generating ink layer 13 overlaps with the internal boundary line 3a or 5a of the upper edge seal portion 3 or the side edge seal portion 5 for a continuous length of 15 mm or more. That is, as shown in Figure 4 or Figure 9, the heat-generating ink layer 13 straddles the center line C of the upper edge seal portion 3 or the side edge seal portion 5, and the length L1 that continuously overlaps with the internal boundary line 3a or 5a of the upper edge seal portion 3 or the side edge seal portion 5 is 15 mm or more. With such a heat-treated packaging bag 1, when heated in a microwave oven, the heat-generating ink layer 13 formed between the base material 11 and the sealant layer 12 in the central part of the upper edge seal portion 3 or the side edge seal portion 5 generates heat when irradiated with microwaves, causing the sealant layer 12 to retract and allow steam to pass through.
[0034] Furthermore, the central part of the upper edge seal portion 3 or the side edge seal portion 5 is the area where the most force is applied when the heat-treated packaging bag 1 expands after being heated in a microwave oven. By forming the heat-generating ink layer 13 in this area, it is possible to selectively cause the seal to retract at this location. If the heat-generating ink layer 13 is formed in an area other than the central part of the upper edge seal portion 3 or the side edge seal portion 5 (for example, the part where the upper edge seal portion 3 and the side edge seal portion 5 intersect), the heat-treated packaging bag 1 may rupture from another location (for example, the central part of the upper edge seal portion 3 and the side edge seal portion 5).
[0035] Furthermore, it is considered that the sealant layer 12 needs to soften over a relatively wide area for seal retraction to occur. In other words, if the length L1 over which the heat-generating ink layer 13 continuously overlaps with the internal boundary line 3a or 5a of the upper edge seal portion 3 or the side edge seal portion 5 is less than 15 mm, the heating region H heated by the heat generated by the heat-generating ink layer 13 is narrow, so seal retraction of the sealant layer 12 does not occur, and the risk of the heat-treated packaging bag 1 rupturing starting from the sealant layer 12 softened only in the narrow heating region H increases. The length L1 over which the heat-generating ink layer 13 continuously overlaps with the internal boundary line 3a or 5a of the upper edge seal portion 3 or the side edge seal portion 5 is preferably 20 to 100 mm, and more preferably 20 to 70 mm. The heat-generating ink layer 13 may be in contact with the internal boundary line 3a or 5a of the upper edge seal portion 3 or the side edge seal portion 5, or, as shown in the embodiment in Figure 4 or Figure 9, it may extend beyond the internal boundary line 3a or 5a of the upper edge seal portion 3 or the side edge seal portion 5 to the inside of the heat-treated packaging bag 1.
[0036] The heat-generating ink layer 13 may be exposed to the outer end surface 3b or 5b of the upper edge seal portion 3 or the side edge seal portion 5, but it is preferable that it be formed inside the outer end surface 3b or 5b of the upper edge seal portion 3 or the side edge seal portion 5, as shown in the embodiment in Figure 4 or Figure 9, and not exposed to the outer end surface 3b or 5b of the upper edge seal portion 3 or the side edge seal portion 5. If the heat-generating ink layer 13 is exposed to the outer end surface 3b or 5b of the upper edge seal portion 3 or the side edge seal portion 5, the upper edge seal portion 3 or the side edge seal portion 5 may peel off due to the influence of moisture from the outside, but if it is not exposed to the outer end surface 3b or 5b of the upper edge seal portion 3 or the side edge seal portion 5, unintended peeling of the upper edge seal portion 3 or the side edge seal portion 5 can be reduced. The distance W0 from the outer end face 3b or 5b of the upper edge seal portion 3 or the side edge seal portion 5 to the end of the heat-generating ink layer 13 is preferably 1 to 5 mm, and more preferably 2 to 4 mm.
[0037] By using such a heat-treated packaging bag 1, when an article 20 filled with contents 21 in the heat-treated packaging bag 1 is heated in a microwave oven, the heat-generating ink layer 13 formed between the base material 11 and the sealant layer 12 in the center of the upper edge seal portion 3 or the side edge seal portion 5 is heated by microwave irradiation, causing the sealant layer 12 to retract and allowing steam to pass through. Therefore, it is possible to suppress scorching or punctures at the opening, and prevent the heat-treated packaging bag 1 from rupturing with the opening as the starting point. [Examples]
[0038] <Example 1> A pillow-shaped heat-treated packaging bag 1 (160 mm long x 120 mm wide, with a back sealing portion 2 width of 10 mm and an upper edge sealing portion 3 width of 10 mm) was produced by heat-sealing the sheet material 10 with a heat sealer, as shown in Figures 1 and 2. The sheet material 10 was a laminated film (Ny#15 / LLDPE#60) in which a microwave heating ink composition (product name: LG-MW Heat Agent, manufactured by Tokyo Ink Co., Ltd.) that would become the heating ink layer 13 was applied to a predetermined position on a 15 μm thick polyamide film that would become the base material 11 using gravure printing, and then a 60 μm thick linear low-density polyethylene film that would become the sealant layer 12 was laminated nonsol using an adhesive. The heating ink layer 13 was formed in the shape (rectangle) shown in Figure 4(a), with L1 being 60 mm and W0 being 3 mm.
[0039] Subsequently, 100g of water was added as the contents 21 from the bottom of the heat-treated packaging bag 1, and the bottom was heat-sealed with a heat sealer (width of the lower edge seal portion 4: 10mm) to prepare test sample E1.
[0040] <Example 2> Test sample E2 was prepared in the same manner as in Example 1, except that L1 was set to 42 mm.
[0041] <Example 3> Test sample E3 was prepared in the same manner as in Example 1, except that L1 was set to 24 mm.
[0042] <Example 4> Test sample E4 was prepared in the same manner as in Example 1, except that the heat-generating ink layer 13 was formed in the shape shown in Figure 4(b) (trapezoidal), with L1 being 56 mm and W0 being 3 mm.
[0043] <Example 5> Test sample E5 was prepared in the same manner as in Example 1, except that the heat-generating ink layer 13 was formed in the shape shown in Figure 4(c) (inverted trapezoid), with L1 being 30 mm and W0 being 3 mm.
[0044] <Comparative Example 1> Test sample C1 was prepared in the same manner as in Example 1, except that L1 was set to 12 mm.
[0045] <Comparative Example 2> Test sample C2 was prepared in the same manner as in Example 1, except that the heat-generating ink layer 13 was formed in the shape shown in Figure 6(a) (vertical slit), with L1 being 2 mm and W0 being 3 mm.
[0046] <Comparative Example 3> Test sample C2 was prepared in the same manner as in Example 1, except that the heat-generating ink layer 13 was formed in the shape shown in Figure 6(b) (dot, dot diameter: 1.4 mm) and W0 was 3 mm.
[0047] <Comparative Example 4> Test sample C4 was prepared in the same manner as in Example 1, except that the position of the heat-generating ink layer 13 was set to the center of the back-bonded portion 2.
[0048] <Rating 1> Thermolabels (registered trademark) were attached to the vicinity of the heat-generating ink layer 13 of the test samples of Example 1 and Comparative Examples 3-4. Each test sample was placed in a microwave oven with the back adhesive portion 2 facing upwards and heated at 600W for 2 minutes. After the heat treatment, the Thermolabels (registered trademark) on the heat-treated packaging bag 1 were examined, and the temperature near the heat-generating ink layer 13 was measured. The results are shown in Table 1.
[0049] <Rating 2> Each test sample was placed in a microwave oven with the back seal portion 2 facing upwards, and heated at 600W until steam could pass through the heat-treated packaging bag 1. The condition of the heat-treated packaging bag 1 (especially the steam-permeable portion) after heating was visually observed and evaluated as follows. The results are shown in Table 1. A. Steam was allowed through due to the seal retraction near the heat-generating ink layer. B. Holes have formed near the heat-generating ink layer. C. The heat-treated packaging bag ruptured starting near the heat-generating ink layer. D. The heat-treated packaging bag ruptured starting from a location different from the area near the heat-generating ink layer.
[0050] [Table 1]
[0051] From the above results, it was found that in the test samples E1 to E5 (L1 of 15 mm or more) manufactured in Examples 1 to 5, steam was allowed through due to seal retraction near the heat-generating ink layer, but in the test samples C1 to C3 (L1 of less than 15 mm) manufactured in Comparative Examples 1 to 3, holes occurred near the heat-generating ink layer 13, or the bag ruptured starting from near the heat-generating ink layer 13. In the test sample C4 manufactured in Comparative Example 4 (with the heat-generating ink layer 13 formed on the back sealing portion 2), the bag ruptured not near the heat-generating ink layer 13, but starting from near the center of the upper edge sealing portion 3. [Explanation of symbols]
[0052] 1 Heat-treated packaging bag 2. Back panel 3. Upper edge sealing portion 3a Internal border 3b External end face 4. Lower edge sealing portion 5. Side edge sealing portion 5a Internal border 5b External end face 10 Sheet members 11 Base material 12. Sealant layer 13. Heat-generating ink layer 20 Goods 21 Contents C Chuo line H heating area Distance from the outer end face of the upper edge seal portion of W0 to the end of the heat-generating ink layer L1 is the length over which the heat-generating ink layer continuously overlaps with the inner boundary line of the upper edge seal.
Claims
1. It consists of a sheet member having a base material and a sealant layer laminated on the surface of the base material, The back-attached portion is formed by welding the sealant layer on both side edges of the sheet member in a gable shape, The sealant layer on the upper edge of the tubular sheet member is welded in a planar manner to form an upper edge seal portion. A pillow-type heat-treated packaging bag having, A heat-generating ink layer that generates heat with microwaves is formed between the substrate and the sealant layer in the central part of the upper edge sealing portion. The heat-generating ink layer overlaps the inner boundary line of the upper edge sealing portion by 15 mm or more in a continuous manner. Heat-treated packaging bags.
2. When microwaves are irradiated in a microwave oven at 600W for 2 minutes, the temperature of the heat-generating ink layer reaches 120-220°C. The heat-treated packaging bag according to claim 1.
3. The heat-generating ink layer is formed in a region that is rectangular in shape when viewed from above. The heat-treated packaging bag according to claim 1.
4. The heat-generating ink layer is not exposed on the outer end surface of the upper edge sealing portion. The heat-treated packaging bag according to claim 1.
5. It consists of a sheet member having a base material and a sealant layer laminated on the surface of the base material, With the two aforementioned sheet members stacked on top of each other, Side edge seal portions formed by welding the sealant layer on both side edges of the sheet member in a planar manner, An upper edge seal portion formed by welding the sealant layer on the upper edge of the sheet member in a planar manner. A three-sided seal type heat-treated packaging bag having, A heat-generating ink layer that generates heat in microwaves is formed between the substrate and the sealant layer in the central part of the upper edge seal portion or the side edge seal portion. The heat-generating ink layer overlaps the inner boundary line of the upper edge seal portion or the side edge seal portion by 15 mm or more in a continuous manner. Heat-treated packaging bags.
6. When microwaves are irradiated in a microwave oven at 600W for 2 minutes, the temperature of the heat-generating ink layer reaches 120-220°C. The heat-treated packaging bag according to claim 5.
7. The heat-generating ink layer is formed in a region that is rectangular in shape when viewed from above. The heat-treated packaging bag according to claim 5.
8. The heat-generating ink layer is not exposed to the outer end surface of the upper edge seal portion or the side edge seal portion. The heat-treated packaging bag according to claim 5.
9. An article comprising a heat-treated packaging bag according to any one of claims 1 to 8, and contents sealed inside the heat-treated packaging bag.