Microwave pouch

Abstract

To provide a pouch for a microwave oven capable of reliably and widely securing an opening at a slit during heating in a microwave oven. [Solution] A microwave pouch (10) in which the automatic steam release mechanism (20) has a steam release seal portion (30), a slit (50), and a flap piece (41), the slit (50) being composed of a slit middle portion (52) formed toward an area closer to the seal peeling start portion (31) than both slit end portions (51), and the automatic steam release mechanism (20) further has an unsealed portion (41) formed to cover the entire periphery of the slit (50), and a control seal portion (70) in which part of the flap piece (41) is heat-sealed to the second film (12).

Description

Technical Field

[0001] The present invention relates to a pouch for a microwave oven having an automatic steam venting mechanism that automatically vents internal steam during heating.

Background Art

[0002] Conventionally, cooked or semi-cooked food is contained in a pouch formed into a bag shape by thermally bonding overlapping films, and there are packaged foods on the market that are heated and cooked by a microwave oven when the food is eaten.

[0003] In such a pouch, when heated in a microwave oven, the internal pressure of the pouch increases due to steam generated from the food and thermal expansion of the internal air, and the pouch may burst or deform, or the food inside the pouch may scatter due to bursting.

[0004] Therefore, in recent years, it is generally known that pouches for microwave ovens are provided with an automatic steam venting mechanism that automatically vents internal steam during heating (for example, see Patent Document 1). As one aspect of such an automatic steam venting mechanism, as shown in FIG. 10, a steam venting seal portion 130 formed by thermally welding overlapping films 111 and 112 and isolating the internal steam release portion 140 therefrom from the content storage portion 114, and a slit 150 formed through the first film 111 in the steam release portion 140 are provided.

[0005] In the automatic steam venting mechanism 120 shown in FIG. 10, when the pressure in the content storage portion 114 increases with heating by a microwave oven, a part of the steam venting seal portion 130 peels off, and the content storage portion 114 and the steam release portion 140 communicate with each other, and the steam in the content storage portion 114 is discharged to the outside through the slit 150.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

[0007] However, with the automatic steam venting mechanism 120 shown in Figure 10, depending on the degree of expansion of the pouch during heating, it may not be possible to ensure a sufficiently large opening in the slit 150. When the opening in the slit 150 is small in this way, it is not possible to ensure sufficient steam discharge, which can cause the pouch to remain expanded due to steam for a long time, potentially leading to perforation of the pouch due to thermal damage to the inner material of the pouch.

[0008] Therefore, the present invention aims to solve these problems and provide a microwave pouch with a simple structure that can reliably and widely secure the opening in the slit when microwave heating. [Means for solving the problem]

[0009] The present invention relates to a microwave oven pouch equipped with an automatic steam release mechanism, wherein the microwave oven pouch is formed into a bag shape by heat-sealing a first film and a second film to form a bag-making seal portion, and the automatic steam release mechanism has a steam release seal portion formed by heat-sealing the overlapping first film and the second film and isolating the inner steam release portion from the contents storage portion, a slit formed in the first film at the steam release portion, and a flap piece formed in the first film and partitioned by the slit, wherein the steam release seal portion releases steam when heated The automatic steam venting mechanism solves the above problem by having a seal peeling initiation portion that starts peeling due to steam generated in the contents storage portion, the slit being composed of both ends of the slit and an intermediate slit portion formed toward a region closer to the seal peeling initiation portion than both ends of the slit and connecting both ends of the slit, and further having an unsealed portion formed to cover the entire circumference of the slit in which the first film and the second film are not welded, and a control seal portion in which a part of the flap piece formed on the first film is heat-welded to the second film. [Effects of the Invention]

[0010] According to the present invention, the automatic steam venting mechanism has an unsealed portion formed to cover the entire circumference of the slit and a control seal portion in which a part of a flap piece formed on the first film is heat-sealed to the second film. When the pouch is heated in a microwave oven, when the steam venting seal portion peels off and the contents storage portion and the steam release portion come into contact, the first and second films tend to separate due to the increase in internal pressure of the pouch on the side closer to the seal peeling start point than the slit. However, in the region where the flap piece is formed, which is further from the seal peeling start point than the slit, the control seal portion prevents the first and second films from separating. As a result, the opening in the slit can be reliably and widely secured, and steam can be discharged effectively. Furthermore, because an unsealed portion is formed to cover the entire circumference of the slit, the first and second films can be reliably separated by an increase in internal pouch pressure on the side closer to the seal peeling start point than the slit. [Brief explanation of the drawing]

[0011] [Figure 1] An explanatory diagram showing a microwave pouch according to the first embodiment of the present invention. [Figure 2] An explanatory diagram showing the automatic steam venting mechanism as viewed from the first film side. [Figure 3] This diagram shows the automatic steam venting mechanism as viewed from the second film side, opposite to Figure 2. [Figure 4] An explanatory diagram showing the automatic steam release mechanism during pouch heating. [Figure 5] An explanatory diagram showing the dimensions of each part. [Figure 6] A photograph showing a pouch with a control seal formed on it being heated. [Figure 7] A photograph showing a heated pouch that does not have a control seal formed on it. [Figure 8] An explanatory diagram showing an automatic steam venting mechanism according to the second embodiment. [Figure 9] An explanatory diagram showing a modified version of the automatic steam venting mechanism. [Figure 10] An explanatory diagram showing a conventional automatic steam venting mechanism. [Modes for carrying out the invention]

[0012] A microwave pouch 10 according to the first embodiment of the present invention will be described below with reference to the drawings.

[0013] First, as shown in Figure 1, the pouch 10 is formed into a bag shape by heat-sealing the overlapping first and second films 11 and 12 (and the gusset film) at predetermined locations to form a bag-making seal section 13, and the contents such as food are stored in the contents-holding section 14 inside.

[0014] Specifically describing the aspect of the pouch 10 in this embodiment, as shown in FIG. 1, the pouch 10 is formed by folding the first and second films 11 and 12 that are continuously formed as a single film in two at the top of the pouch 10, and arranging a gusset film (not shown) between the first and second films 11 and 12 at the bottom of the pouch 10. By thermally welding between the first and second films 11 and 12 or between the first and second films 11 and 12 and the gusset film (not shown) at both sides and the bottom of the pouch 10, the bag-making seal portions 13 (side seal portions 13a, 13b, bottom seal portion 13c) are formed, and thus it is configured as a so-called standing pouch formed in a bag shape. As shown in FIG. 1, notch-shaped cuts 15 for opening the pouch 10 are formed at two positions above the steam vent seal portion 30, which will be described later, and at positions facing it in the side seal portions 13a and 13b.

[0015] An automatic steam vent mechanism 20 for automatically venting the steam inside the pouch 10 to the outside during heating is provided in the pouch 10.

[0016] As shown in FIGS. 1 and 2, the automatic steam vent mechanism 20 includes a steam vent seal portion 30 formed by thermally welding the overlapping first and second films 11 and 12 to isolate the steam release portion 40 inside it from the content storage portion 14, a slit 50 formed in the first film 11 in the steam release portion 40, and a flap piece 60 formed in the first film 11 and partitioned by the slit 50.

[0017] Hereinafter, each component of the automatic steam vent mechanism 20 will be described based on FIG. 2.

[0018] First, as shown in FIG. 2, the steam vent seal portion 30 is formed continuously with the bag-making seal portion 13 (side seal portion 13a) inside the bag-making seal portion 13. The steam vent seal portion 30 has a seal peeling initiation portion 31 that begins to peel off due to steam generated inside the contents storage portion 14 during microwave heating (so that the outer and inner sides of the steam vent seal portion 30 are in communication). In this embodiment, as shown in Figures 1 and 2, the seal peeling initiation portion 31 is the part of the annular steam vent seal portion 30 closest to the center C of the contents storage portion 14.

[0019] As shown in Figure 2, the steam vent section 40 is a part that is isolated from the contents storage section 14 by forming a steam vent seal section 30. In this embodiment, the steam vent section 40 is surrounded by the steam vent seal section 30 and the bag-making seal section 13 (specifically, the side seal section 13a).

[0020] As shown in Figure 2, the slit 50 is formed by penetrating the first film 11 in the film thickness direction, and consists of a pair of slit ends 51 and a substantially arc-shaped (substantially C-shaped or U-shaped) slit intermediate portion 52 that is formed toward a region closer to the seal peeling start portion 31 than the slit ends 51 (the side closer to the seal peeling start portion 31 than the imaginary line passing through the pair of slit ends 51) and connects the slit ends 51. In this embodiment, the positions of the ends 51 of the slit are determined such that the imaginary line connecting the ends 51 of the slit extends along the vertical direction (up and down direction in Figure 1) of the microwave pouch 10 (parallel to the side seal portion 13a). Furthermore, in the first embodiment, as shown in Figure 3, the second film 12 does not have a slit formed in the vapor release portion 40.

[0021] As shown in Figure 2, the flap piece 60 is a portion that is partially separated from the peripheral portion of the first film 11 in the vapor release section 40 by forming a slit 50. The flap piece 60 has a connecting portion 61 at a position on its outer periphery that is far from the seal peeling start portion 31, which is connected to the peripheral portion of the first film 11.

[0022] As shown in Figure 2, the automatic steam release mechanism 20 further includes an unsealed portion 41 formed to cover the entire circumference of the slit 50 in the steam release portion 40, and a control seal portion 70 formed by heat-welding a part of the flap piece 60 formed on the first film 11 to the second film 12.

[0023] The unsealed portion 41 is the area where the overlapping first and second films 11 and 12 have not been welded together. As shown in Figure 2, when the microwave pouch 10 is viewed from above, it is formed to completely cover the entire circumference of the slit 50 in the planar direction of the pouch. In this embodiment, the unsealed portion 41 is formed over the entire area of ​​the steam release portion 40, excluding the area where the control seal portion 70 is formed.

[0024] The control seal portion 70 is the area where the overlapping first and second films 11 and 12 are welded together. As shown in Figure 2, it is formed continuously with the bag-making seal portion 13 (side seal portion 13a) so as to protrude laterally toward the inside of the pouch from the bag-making seal portion 13 (side seal portion 13a), and a part of the flap piece 60 is heat-welded to the second film 12 at a part of it (the tip).

[0025] Next, the dimensions of each part are as follows:

[0026] First, from the viewpoint of effectively demonstrating the effect of the control seal portion 70 (that is, the effect of preventing the first and second films 11 and 12 from separating by the control seal portion 70, thereby ensuring a large and reliable opening in the slit 50), as shown in Figure 5, it is preferable to set the distance γ between the point in the slit 50 that is furthest inside the pouch in the direction of the imaginary line connecting both ends of the slit 51 (in other words, the direction in which the connecting portion 61 extends) and the control seal portion 70 to 4 mm or less, and it is even more preferable to set the distance γ to 3 mm or less.

[0027] Furthermore, when the steam vent seal portion 30 peels off during pouch heating, it is preferable to prevent the steam passage formed between the peeled portion of the steam vent seal portion 30 and the slit 50 from becoming blocked again, thereby ensuring good steam release. As shown in Figure 5, it is preferable to set the distance β between the slit 50 at the point furthest inside the pouch in the direction perpendicular to the imaginary line connecting both ends of the slit 51 (in other words, the direction in which the connecting portion 61 extends) (in the examples shown in Figures 1 and 5, the horizontal direction of the microwave pouch 10, the left-right direction in the drawing) and the steam vent seal portion 30 to 4 mm or less, and it is even more preferable to set the distance β to 3 mm or less.

[0028] Furthermore, from the viewpoint of ensuring a large opening in the slit 50 when heating the pouch, it is preferable to set the distance σ between both ends 51 of the slit to 5 mm or more, as shown in Figure 5, and it is even more preferable to set the distance σ to 7 to 10 mm or less.

[0029] Next, the appearance of each part of the pouch 10 of this embodiment when it is heated will be described below.

[0030] First, when the pouch 10 is heated in a microwave oven, the internal pressure of the pouch 10 increases due to the steam generated from the contents such as food and the thermal expansion of the internal air, and a force is applied radially from the center C (see Figure 1) of the contents storage section 14.

[0031] Next, due to the radially spreading force, the steam vent seal portion 30 begins to peel off from a point close to the center C of the contents storage portion 14 (near the seal peeling start point 31), and this peeling of the steam vent seal portion 30 progresses in a direction away from the center C of the contents storage portion 14.

[0032] Furthermore, as the peeling of the steam vent seal portion 30 progresses, the unsealed portion 41 of the steam release portion 40 also peels away from the center C of the contents storage portion 14. In other words, in the unsealed portion 41 of the steam release portion 40, the first and second films 11 and 12 are in close contact with each other before the steam release seal portion 30 begins to peel off. However, after the steam release seal portion 30 begins to peel off, the peeling progresses in a direction away from the center C of the contents storage portion 14 due to the radially spreading force described above.

[0033] Next, when the separation between the first and second films 11 and 12 in the steam-venting seal section 30 and the unsealed section 41 reaches the position of the slit 50, the steam inside the contents-containing section 14 is released to the outside of the pouch 10 through the slit 50.

[0034] At this time, in the area closer to the seal peeling start section 31 than the slit 50 (area A shown in Figure 4), the internal pressure inside the pouch 10 causes the first and second films 11 and 12 to try to separate. However, in the area where the flap piece 60 is formed, which is further from the seal peeling start section 31 than the slit 50 (area B shown in Figure 4), the control seal section 70 prevents the first and second films 11 and 12 from separating. As a result, the first film 11 in area A and the first film 11 in area B are separated significantly in the front-to-back direction of the pouch, with the slit 50 as the boundary. Consequently, as shown in Figure 6, a large opening can be secured at the slit 50, ensuring sufficient steam release. Therefore, after heating the pouch in a microwave oven and steam begins to escape from the pouch (after steam release), the internal pressure of the pouch can be maintained at a low internal pressure of 1.10 kgf / cm2 or less, eliminating the risk of the pouch rupturing. Figure 7 shows, as a comparative example, an example in which a pouch without the control seal portion 70 shown in Figure 10 is heated, and a sufficiently large opening cannot be secured in the slit 150. As shown in Figure 7, if a sufficiently large opening cannot be secured in the slit 150, sufficient steam cannot be released. As a result, the internal pressure of the pouch after steam release tends to be higher than 1.10 kgf / cm2, increasing the risk of the pouch rupturing.

[0035] Furthermore, since the unsealed portion 41 is formed to cover the entire circumference of the slit 50 at this time, the first and second films 11 and 12 can be reliably separated on the side closer to the seal peeling start portion 31 than the slit 50 (area A shown in Figure 4).

[0036] Next, a microwave pouch 10 according to the second embodiment of the present invention will be described with reference to Figure 8. Here, in the second embodiment, except for some components, it is exactly the same as the first embodiment described above, so the description of components other than the differences will be omitted.

[0037] Figure 8(a) is an explanatory diagram showing the pouch 10 according to the second embodiment as viewed from the first film 11 side, and Figure 8(b) is an explanatory diagram showing the pouch 10 as viewed from the second film 12 side, which is the opposite side from Figure 8(a).

[0038] First, in the first embodiment described above, as shown in Figures 2 and 3, it was explained that in the steam release section 40, the slit 50 is formed only in the first film 11 and no slit is formed in the second film 12. However, in the second embodiment, as shown in Figure 8, a slit (second slit 53) is also formed in the second film 12 in the steam release section 40.

[0039] In other words, in the second embodiment, as shown in Figure 8, the second film 12 has a second slit 53 formed in the first film 11 that is the same shape and in the same position as the slit 50 formed in the first film 11, so as to completely overlap the slit 50 formed in the first film 11 in the front-to-back direction.

[0040] The second slit 53 formed in the second film 12, like the slit 50 formed in the first film 11, is formed to penetrate the second film 12 in the film thickness direction, and as shown in Figure 8(b), it consists of slit ends 54 and a roughly arc-shaped (roughly C-shaped or roughly U-shaped) slit intermediate portion 55 that is formed toward the area closer to the seal peeling start portion 31 than the slit ends 54 and connects the slit ends 54.

[0041] Furthermore, in the second embodiment, a second flap piece 62 is formed on the second film 12, similar to the flap piece 60 formed on the first film 11, as shown in Figure 8(b). As shown in Figure 8(b), the second flap piece 62 is a portion that is partially separated from the peripheral portion of the second film 12 at the steam release portion 40 by the formation of the second slit 53, and has a connecting portion 63 that is connected to the peripheral portion of the second film 12 at a position on its outer periphery that is far from the seal peeling start portion 31. In the second embodiment, a portion of the flap piece 60 formed on the first film 11 is heat-sealed to a portion of the second flap piece 62 formed on the second film 12 by the control seal portion 70.

[0042] In the pouch 10 obtained according to the second embodiment, since the second slit 53 is also formed in the second film 12, even if steam cannot be released solely from the slit 50 formed in the first film 11, such as when the pouch 10 is placed in a microwave oven with the first film 11 side down, steam can be released from the second slit 53 formed in the second film 12, thereby improving the reliability of steam release. Furthermore, compared to the case where the slit 50 is formed only in the first film 11, since the slits 50 and 53 can be formed at once after the first film 11 and the second film 12 are welded together to form the steam vent seal portion 30, the slits 50 and 53 can be reliably positioned in predetermined locations within the steam vent seal portion 30.

[0043] Although embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various design modifications can be made without departing from the present invention as described in the claims.

[0044] For example, the pouch 10 may be constructed by arbitrarily combining the various embodiments and modified configurations described above. Furthermore, the specific forms of each film constituting the pouch 10 (first and second films 11 and 12, and gusset film) can be any known synthetic resin films such as polyester, polypropylene, and polyamide, or known synthetic resin films such as coating films or vapor-deposited films that provide gas barrier properties or moisture barrier properties to these synthetic resin films, or any synthetic resin film formed by laminating paper or aluminum foil onto the synthetic resin film. Furthermore, although the above-described embodiment assumed that the pouch 10 is formed as a so-called standing pouch, the specific form of the pouch 10 can be anything, such as a pouch without a gusset film between the first and second films 11 and 12, as long as it has first and second films 11 and 12 arranged in a stacked manner. Furthermore, although the embodiments described above assumed that the first and second films 11 and 12 were integrally formed as a single film, the first and second films 11 and 12 may be formed separately. Furthermore, although the above-described embodiment was explained assuming that the contents of the pouch 10 are food, the specific form of the contents is not limited to food.

[0045] Furthermore, in the embodiments described above, the steam venting seal portion 30 was described as being formed continuously with the bag-making seal portion 13 (the side seal portion 13a). However, the specific form of the steam venting seal portion 30 is not limited to the above, and as shown in Figure 9(a), it may be formed independently on the inside of the bag-making seal portion 13. Furthermore, as a variation of the steam vent seal portion 30, the position of the seal peeling start portion 31, which begins to peel due to steam generated inside the contents storage portion 14 during microwave heating, may be adjusted by varying the strength of peeling resistance (resistance to communication between the outer and inner sides of the steam vent seal portion 30 due to the progression of peeling) in each part of the steam vent seal portion 30, such as forming strong seal portions and weak seal portions with different peeling resistances in the steam vent seal portion 30.

[0046] Furthermore, although the above-described embodiment assumed that the control seal portion 70 is formed continuously with the bag-making seal portion 13, the specific form of the control seal portion 70 is not limited to the above. As shown in Figure 9(b), the control seal portion 70 may be formed as a point seal that heat-welds a part of the flap piece 60 to the second film 12 at a position independent of the bag-making seal portion 13.

[0047] Furthermore, although the above-described embodiment was explained as having a substantially arc shape (substantially C-shaped or U-shaped) intermediate portion 52 of the slit 50, it can be any shape as long as it is formed from both ends 51 of the slit toward a region closer to the seal peeling start portion 31 and connects both ends 51 of the slit. For example, the intermediate portion 52 of the slit may be formed from multiple straight or curved lines, such as a V-shape or a U-shape. Furthermore, although the above-described embodiment assumed that the slit 50 is a linear cut (a cut without width), the specific form of the slit 50 is not limited to this, and the slit 50 may be formed to have a predetermined width (width in a direction perpendicular to the extending direction of the slit 50). [Explanation of symbols]

[0048] 10... Pouch (microwave pouch) 11 ··· Film 1 12 ··· Film 2 13 ··· Seal section for bag making 13a ··· Side seal section 13b ··· Side seal section 13c ··· Bottom seal section 14 ··· Contents storage compartment 15 ··· Notch 20... Automatic steam release mechanism 30... Steam vent seal section 31...Start of seal peeling 40... Steam release section 41 ··· Unsealed section 50 ··· Slit 51... Slit ends 52 ··· Slit middle section 53 ··· Second Slit 54... Slit ends 55 ··· Slit middle section 60 ··· Flap piece 61... Connection part 62 ··· Second flap 63... Connection part 70 ··· Control seal section C... Center of the contents storage area

Claims

1. A microwave pouch equipped with an automatic steam release mechanism, The microwave pouch is formed into a bag shape by heat-sealing a first film and a second film together to form a seal portion for bag making. The automatic steam venting mechanism has a steam venting seal portion formed by heat-sealing the overlapping first film and the second film, which isolates the steam vent portion on its inside from the contents storage portion, a slit formed in the first film at the steam vent portion, and a flap piece formed in the first film and partitioned by the slit. The steam venting seal portion has a seal peeling initiation portion which begins to peel off due to steam generated in the contents storage portion when heated, The slit is composed of slit ends and a slit intermediate portion that is formed toward a region closer to the seal peeling initiation point than the slit ends and connects the slit ends. The microwave pouch is characterized in that the automatic steam release mechanism further comprises an unsealed portion formed to cover the entire circumference of the slit, where the first film and the second film are not welded together, and a control sealing portion in which a part of the flap piece formed on the first film is heat-sealed to the second film.

2. The microwave pouch according to claim 1, characterized in that the second film has a second slit formed in the first film at the steam release portion, which is the same shape and position as the slit formed in the first film and overlaps the slit formed in the first film in the front-back direction.

Images