Pouch for microwave oven

Abstract

To provide a pouch for a microwave oven that easily releases steam during heating and can prevent deformation of a portion provided with an automatic steam removal mechanism after filling contents.SOLUTION: A pouch for a microwave oven 100 has a rectangular outer shape in plan view and comprises an automatic steam removal mechanism 120. The automatic steam removal mechanism 120 includes a steam release portion 121, and a steam removal seal portion 125 surrounding a periphery of the steam release portion 121. The steam removal seal portion 125 is formed so as to be located within a width region of a seal peeling start portion P of the steam removal seal portion 125 whose circumference of an inscribed ellipse E is closest to a center point O of an accommodating portion 110 or in the vicinity of the seal peeling start portion when assuming the inscribed ellipse E in contact with a center of an inner edge of each side of a peripheral seal portion 115 of the pouch.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pouch for use in a microwave oven, which is formed into a bag shape by thermally bonding overlapping laminated films and is equipped with an automatic steam release mechanism that automatically releases internal steam when heated. [Background technology]

[0002] Conventionally, packaged foods available on the market are prepared by placing cooked or semi-cooked food in a pouch formed by thermally bonding overlapping laminated films, and heating and cooking the food in a microwave oven when the food is to be eaten.

[0003] Such microwave pouches are generally provided with an automatic steam release mechanism that automatically releases internal steam when heated. Known automatic steam release mechanisms include those in which a portion of a laminated film is heat-bonded to provide an annular steam release seal portion, and steam is released by peeling back a portion of the steam release seal portion.

[0004] In such an automatic steam release mechanism, the position of the steam release seal portion affects the ease of steam release during heating in a microwave oven and the deformation of the pouch after filling. If the seal recession of the peripheral seal portion during heating is large, the pouch may break at the peripheral seal portion. Furthermore, if the pouch is significantly deformed after filling, this will have a negative effect on transportation in the filling equipment, insertion into a box, and appearance.

[0005] For example, Patent Document 1 describes forming a steam release seal portion so that the initial breaking point of the steam release seal portion closest to the center point of the pouch containing portion is located on or inside the circumference of a circle inscribed in the center of the inner ends of the peripheral seal portions of the two short sides. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 4029590 Summary of the Invention [Problem to be solved by the invention]

[0007] However, it has been revealed that even when a steam release seal portion is provided as in Patent Document 1, if the distance between the position of the initial breaking point of the steam release seal portion and the center point of the pouch containing portion is too large, steam release becomes difficult and seal recession occurs in the peripheral seal portion, and that if the distance between the position of the initial breaking point of the steam release seal portion and the center point of the pouch containing portion is too small, steam release is easy but the pouch after filling will be significantly deformed.

[0008] The present invention has been made to solve the above-mentioned problems, and has as its object to provide a pouch for use in a microwave oven which allows steam to escape easily when heated and which can prevent deformation of the portion equipped with the automatic steam release mechanism after the pouch is filled with the contents. [Means for solving the problem]

[0009] The microwave pouch of the present invention has an outer shape that is rectangular in a plan view and is equipped with an automatic steam release mechanism, the automatic steam release mechanism comprising a steam release section and a steam release seal section that surrounds the periphery of the steam release section, and the steam release seal section is configured such that, when an inscribed ellipse is imagined that contacts the center of the inner end of each side of the peripheral seal section of the pouch, the periphery of the inscribed ellipse is located within the width region of the seal peel start portion of the steam release seal section that is closest to the center point of the storage section or in the vicinity of the seal peel start portion, thereby solving the above-mentioned problems. Effect of the Invention

[0010] According to the invention of claim 1, the steam release seal portion is formed so that the periphery of an inscribed ellipse that touches the center of the inner ends of each side of the peripheral seal portion of the pouch is positioned within the width area of ​​the seal peel start portion of the steam release seal portion that is closest to the center point of the containing portion or in the vicinity of the seal peel start portion.This makes it possible to release steam by peeling back the steam release seal portion without peeling off the peripheral seal portion in response to the force of internal pressure spreading from the center point of the containing portion, while suppressing deformation of the portion where the automatic steam release mechanism is provided, such as warping of the steam release seal portion due to the pressure of the contents after filling.

[0011] According to the invention of claim 2, the steam release seal portion is formed so that the initial breaking point, which is the outer end of the seal peeling starting part of the steam release seal portion, is tangent to the circumference of the inscribed ellipse. This makes it possible to bring the initial breaking point as close as possible to the center point of the storage portion, thereby further improving the steam release performance. According to the invention of claim 3, the steam release seal portion has a seal strength equivalent to that of the peripheral seal portion, so that the steam release seal portion has the necessary seal strength but is easier to peel off than the peripheral seal portion, and it is possible to reliably prevent the peripheral seal portion from peeling off before the seal peel initiation portion of the steam release seal portion peels back. According to the invention of claim 4, since the steam release seal portion is provided so as to be continuous with the peripheral seal portion, it is possible to reliably prevent warping of the steam release seal portion after the contents are filled. [Brief description of the drawings]

[0012] [Figure 1] 1 is a plan view showing an example of the configuration of a microwave pouch according to a first embodiment of the present invention. FIG. [Diagram 2] FIG. 2 is an enlarged view showing a portion of the microwave pouch shown in FIG. [Diagram 3] 2 is a cross-sectional view showing a schematic diagram of a part of the configuration of the cross section AA in FIG. 1. [Figure 4] FIG. 4 is a plan view showing an example of the configuration of a microwave pouch according to a second embodiment of the present invention. [Diagram 5] 5 is a cross-sectional view showing a schematic part of the configuration of the cross section BB in FIG. 4. [Figure 6] FIG. 2 is a diagram illustrating the positions at which steam release seal parts are formed in the microwave pouches produced in Comparative Examples 1 to 6. [Figure 7] FIG. 13 is a diagram illustrating the positions at which steam release seal parts are formed in the microwave pouches produced in Comparative Examples 7 to 12. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The microwave pouch of the present invention is formed by heat-sealing stacked laminated films into a bag shape, and is provided with an automatic steam release mechanism that automatically releases steam inside the pouch to the outside when heated.

[0014] The laminated film may be any film formed by laminating a known synthetic resin film, such as a synthetic resin film made of a thermoplastic resin such as polyester, polypropylene, or polyamide, or a coating film or a vapor deposition film having gas barrier properties or moisture barrier properties onto the synthetic resin film, or by laminating paper or a metal-containing layer onto the synthetic resin film.

[0015] BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a pouch for use in a microwave oven according to the present invention;

[0016] First Embodiment A microwave pouch (hereinafter simply referred to as "pouch") 100 according to a first embodiment of the present invention is configured as a flat pouch having, for example, a rectangular outer shape in plan view, as shown in Figs. 1 to 3. This pouch 100 is formed into a bag shape by forming a peripheral seal portion 115 by heat-sealing the edges of a pair of overlapping front side films 101 and back side films 102, and contents such as food are contained in a storage portion 110 surrounded on all four sides by the peripheral seal portion 115. The peripheral seal portion 115 includes a top seal portion 116 in which the upper edges of the front side film 101 and the back side film 102 are heat-sealed, a side seal portion 117 in which the left and right side edges of the front side film 101 and the back side film 102 are heat-sealed, and a bottom seal portion 118 in which the lower edges of the front side film 101 and the back side film 102 are heat-sealed. At the intended opening location of peripheral seal 115, a notch 105 is provided to facilitate opening of pouch 100 after heating has been completed.

[0017] The pouch 100 is provided with an automatic steam release mechanism 120 that automatically releases steam within the storage section 110 to the outside when heated. The automatic steam release mechanism 120 includes a steam release section 121 and a steam release seal section 125 that surrounds the periphery of the steam release section 121 to isolate the steam release section 121 from the storage section 110.

[0018] The steam release portion 121 is formed, for example, as an unsealed portion where the front side film 101 and the back side film 102 are not thermally bonded together. The specific form of the steam release portion 121 is not limited to this, and the steam release portion 121 may be formed, for example, as a weakly bonded portion that has been thermally bonded so that the seal strength is lower than that of the peripheral seal portion 115 and the steam release seal portion 125, or as a patterned bonded portion that has been subjected to a knurled seal or the like on a pair of laminated films.

[0019] The steam release section 121 is provided with a steam vent section 122 formed as a hole or a slit. The steam release portion 122 is formed, for example, as a through hole having a flattened elliptical opening shape that extends at an angle relative to the side edge of the pouch. Note that the steam release portion 122 does not need to be provided so as to penetrate both the front side film 101 and the back side film 102, and may be provided only in one of the front side film 101 and the back side film 102.

[0020] The steam release seal part 125 is formed by thermally bonding the front side film 101 and the back side film 102, and is configured to gradually peel back as the internal pressure of the storage part 110 increases when heated. The seal peeling start part P, where peeling begins due to steam generated inside the pouch 100, is the part on the outer edge of the steam release seal part 125 that is closest to the center point O of the storage part 110, and the outer end of the seal peeling start part P becomes the initial breaking point Q.

[0021] The steam release seal portion 125 is formed, for example, in a semicircular ring shape in a plan view, and both ends are provided so as to continue to one of the side seal portions 117. The steam release seal portion 115 may be provided so as to continue to the top seal portion 116, or may be provided separately from the peripheral seal portion 115.

[0022] In this embodiment, the steam release portion 121 is described as being formed as an unsealed portion, but in the case of a pouch type that does not have an unsealed portion, the steam release portion 121 is the portion of the steam removal portion 122 that is closest to the center point O of the storage portion 110.

[0023] In the pouch 100 of this embodiment, when an inscribed ellipse E is assumed to be in contact with the center positions of the inner ends of the two short-side peripheral seal portions 115, i.e., the top seal portion 116 and the bottom seal portion 118, and the center positions of the inner ends of the two long-side peripheral seal portions 115, i.e., the left and right side seal portions 117, 117, the steam release seal portions 125 are provided near the four corners of the pouch 100 such that the periphery of the inscribed ellipse E is located within the width region of the seal peeling start portion P. The ellipticity of the inscribed ellipse E, i.e., the ratio of the minor axis to the major axis, is 0.6 to 0.97, and the center point of the inscribed ellipse E is the center point O of the storage portion 110.

[0024] When pouch 100 is heated, water vapor and the like generated from the contents causes pouch 100 to expand radially from center point O of storage section 110 toward peripheral seal portion 115. However, since the outer shape of pouch 100 is rectangular when viewed in a plane, the space within storage section 110 expands into an approximately ellipsoidal shape, and it is believed that the force of the internal pressure spreading from the side of center point O of storage section 110 acts on the surface of this approximately ellipsoidal expanded storage section. Thus, in the pouch 100 of this embodiment, the steam release seal portion 125 is formed so that the periphery of an inscribed ellipse E that contacts the center of the inner ends of each side of the peripheral seal portion 115 of the pouch 100 is positioned within the width region of the seal peel start portion P, so that the force of the internal pressure spreading from the center point O side of the storage portion 110 can be effectively applied to the seal peel start portion P, and therefore steam can be released through the steam release portion 122 by peeling back the steam release seal portion 125 from the seal peel start portion P without peeling off the peripheral seal portion 115. Moreover, the distance L between the initial breaking point Q, which is the outer end of the seal peel start portion P of the steam release seal portion 125, and the center point O of the pouch storage portion 110 can be sufficiently ensured, so that deformation of the portion where the automatic steam release mechanism 120 is provided, such as warping of the steam release seal portion 125 due to the pressure of the contents after filling, can be suppressed.

[0025] It is preferable that the steam release seal portion 125 is provided so that the initial breaking point Q, which is the outer end of the seal peeling start portion P, is in contact with the circumference of the inscribed ellipse E. This makes it possible to bring the initial breaking point Q at the seal peeling start portion P as close as possible to the center point O of the storage portion 110, thereby further improving the steam release performance.

[0026] Steam release seal portion 125 has a seal strength at room temperature that is equal to that of peripheral seal portion 115. This makes steam release seal portion 125 easier to peel off than peripheral seal portion 115 while having the required seal strength, and makes it possible to reliably prevent peripheral seal portion 115 from peeling off before seal peel start portion P of steam release seal portion 125 peels back.

[0027] In the above-mentioned first embodiment, the microwave pouch is configured as a flat pouch, but the shape of the microwave pouch is not limited to this, and it may be configured as, for example, a standing pouch.

[0028] Second Embodiment A microwave pouch (hereinafter simply referred to as "pouch") 200 according to the second embodiment of the present invention is configured as a standing pouch having a rectangular outer shape in a plan view and a gusset portion 211 at the bottom, as shown in Figures 4 and 5. This pouch 200 is formed into a bag shape by heat welding, at predetermined locations, a top-down front side film 201 and a back side film 202, and a bottom film 203 that is folded in half and sandwiched between the front side film 201 and the back side film 202, to form a peripheral seal portion 215. The peripheral seal portion 215 includes a top seal portion 216 in which the upper edges of the overlapping front side film 201 and back side film 202 are heat-sealed, side seal portions 217, 217 in which the left and right side edges of the front side film 201 and back side film 202 are heat-sealed, and a bottom seal portion 218 in which each folded piece 204, 204 of the bottom film 203 is heat-sealed to the bottom end portions of the front side film 201 and back side film 202.

[0029] In the pouch 200 of this embodiment, assuming an inscribed ellipse E that contacts the center positions of the inner ends of the two short-side peripheral seal portions 215, i.e., the top seal portion 216 and the bottom seal portion 218, and the center positions of the inner ends of the two long-side peripheral seal portions 215, i.e., the left and right side seal portions 217, 217, the steam release seal portions 125 in the automatic steam release mechanism 120 are provided in the vicinity of the four corner portions of the pouch 200 such that the periphery of the inscribed ellipse E is located within the width region of the seal peeling start portion P. Here, the ellipticity of the inscribed ellipse E, i.e., the ratio of the minor axis to the major axis, is 0.6 to 0.97, and the center point of the inscribed ellipse E is the center point O of the storage portion 210. The automatic steam release mechanism 120 has the same configuration as that of the pouch 100 according to the first embodiment.

[0030] In the pouch 200 according to the second embodiment, from the viewpoint of improving steam release performance, it is preferable that the steam release seal portion 125 is arranged so that the initial breaking point Q, which is the outer end of the seal peeling start portion P, is tangent to the circumference of the inscribed ellipse E.

[0031] Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment, and various design modifications can be made without departing from the present invention described in the claims. For example, the steam release seal portion does not need to be provided so as to be continuous with the peripheral seal portion, but may be provided independently inside the peripheral seal portion. The steam release seal portion may be formed in other shapes, such as a rectangular ring, and the dimensions of the steam release seal portion may be appropriately selected. Furthermore, when the steam release portion is formed as a hole, the opening shape of the hole does not have to be elliptical, and may be any shape, such as circular, oval, triangular, rectangular, trapezoidal, rice ball-shaped, etc., and the dimensions of the slit may also be selected appropriately. The steam release portion may also be formed as a slit, and the shape of the slit may be any shape, such as semicircular, arcuate, inequality-shaped, straight, etc., and the dimensions of the slit may also be selected appropriately. EXAMPLES

[0032] The present invention will be further described below with reference to examples, but the present invention is not limited to these specific examples.

[0033] <Example 1> With reference to the configuration shown in Figures 1 to 3, a microwave pouch according to the present invention (hereinafter referred to as "pouch 1") was produced in which the steam release seal portion is formed so that the outer end of the seal peeling start portion is in contact with the periphery of an inscribed ellipse that is in contact with the center of the inner ends of each side of the peripheral seal portion of the pouch. The position at which the steam release seal portion is formed is such that the angle θ between the line connecting the center point of the storage portion and the center position of the inner end of the top seal portion and the line connecting the center point of the storage portion and the outer end of the seal peeling start portion is 48°, and the distance L from the center point of the storage portion to the initial breaking point, which is the outer end of the seal peeling start portion, is 68 mm. The steam release seal was formed in a semicircular ring shape with an inner diameter of 11 mm and an outer diameter of 18 mm. The seal strength of the steam release seal was equal to that of the peripheral seal at room temperature. The width of the peripheral seal was 6 mm.

[0034] The above pouch 1 was filled with 150 g of water, and the presence or absence of deformation of the pouch corner portion where the steam release seal portion was formed was visually observed. The state of steaming was also examined by heating the filled pouch 1 in a microwave oven with a rated output of 600 W. The evaluation was made as follows: if the peripheral seal did not recede and the pouch did not break, it was marked "Good", if the peripheral seal did recede but the pouch did not break, it was marked "Good", and if the pouch broke, it was marked "Poor". The results are shown in Table 1 below.

[0035] <Examples 2 to 9> Eight types of microwave pouches (hereinafter referred to as "Pouch 2" to "Pouch 9") were produced that had the same configuration as Pouch 1 produced in Example 1, except that either or both of the outer shape of the pouch and the position of the steam release seal portion were changed according to Table 1 below. For each of these eight types of pouches 2 to 9, the presence or absence of deformation of the pouch corners after filling with the contents was visually observed, and the steaming state during heating was examined in the same manner as in Example 1. The results are shown in Table 1 below.

[0036] <Comparative Examples 1 to 6> As shown in Fig. 6, six types of comparative microwave pouches (hereinafter referred to as "Comparative Pouch 1" to "Comparative Pouch 6") were produced that had the same configuration as pouch 1 produced in Example 1, except that the steam release seal portion was formed so that the initial breaking point Q was located on the circumference of an inscribed circle R1 that contacted the center of the inner ends of the peripheral seal portions of the two short sides of the pouch, and either or both of the outer shape of the pouch and the position of the steam release seal portion were changed according to Table 2 below. The area S surrounded by a circular dashed line in Fig. 6 is the position of the steam release seal portion, shown diagrammatically. For each of these six types of comparative pouches 1 to 6, the presence or absence of deformation of the pouch corners after filling with the contents was visually observed, and the steaming state during heating was examined in the same manner as in Example 1. The results are shown in Table 2 below.

[0037] <Comparative Examples 7 to 12> As shown in Fig. 7, six types of comparative microwave pouches (hereinafter referred to as "Comparative Pouch 7" to "Comparative Pouch 12") were produced that have the same configuration as pouch 1 produced in Example 1, except that the steam release seal portion was formed so that the initial breaking point Q was located on or near the circumference of inscribed circle R2 that contacted the center of the inner ends of the peripheral seal portions of the two long sides of the pouch, and either or both of the outer shape of the pouch and the position of the steam release seal portion were changed according to Table 2 below. The area S surrounded by a circular dashed line in Fig. 7 is the position of the steam release seal portion, shown diagrammatically. For each of these six types of comparative pouches 7 to 12, the presence or absence of deformation of the pouch corners after filling with the contents was visually observed, and the steaming state during heating was examined in the same manner as in Example 1. The results are shown in Table 2 below.

[0038] [Table 1]

[0039] [Table 2]

[0040] As shown by the above results, it was confirmed that with pouches 1 to 9 according to the present invention, there is no warping of the pouch corners after filling with the contents, and steam can be passed through the steam release seal without the pouch breaking when heated in a microwave oven. Furthermore, it was confirmed that when the outer diameter shape has a small ellipticity of the inscribed ellipse, it is advantageous in terms of safe steaming to form the steam release seal at a position where the distance from the center point of the containing portion to the outer edge of the seal peel start portion is small. On the other hand, in Comparative Pouches 1 to 6, although warping of the pouch corners after filling with the contents could be suppressed, it was confirmed that the pouch broke from the side seal when heated in a microwave oven. Furthermore, in comparative pouches 7 to 12, steam could be passed through the steam release seal without the pouch breaking when heated in a microwave oven, but it was confirmed that the pouch corners were noticeably warped after the contents were filled. [Explanation of symbols]

[0041] 100,200 ··· Microwave pouch 101,201 ··· Surface film 102,202 ··· Back side film 203 Bottom film 204 ··· Folded piece 105 ··· Notch 110,210 ··· Storage section 211 ··· Gusset 115,215 Peripheral seal 116,216 Top seal part 117,217 Side seal part 118,218 Bottom seal part 120 Automatic steam release mechanism 121 Steam release section 122 Steam release section 125 Steam release seal E: Inscribed ellipse O: Center point of the housing P: Seal peeling start point Q: Initial break point R1: Inscribed circle R2: Inscribed circle S: Steam release seal part formation position

Claims

1. A microwave pouch having an automatic steam release mechanism and a rectangular outer shape in a plan view, The automatic steam release mechanism includes a steam release portion and a steam release seal portion surrounding the periphery of the steam release portion, a pouch for use in a microwave oven, the steam release seal portion being formed such that, when an inscribed ellipse is imagined which contacts the centers of the inner ends of each side of the peripheral seal portion of the pouch, the periphery of the inscribed ellipse is positioned within the width region of the seal peel start portion of the steam release seal portion which is closest to the center point of the containing portion or in the vicinity of the seal peel start portion.

2. 2. The pouch for use in a microwave oven according to claim 1, wherein the steam release seal portion is formed so that an outer edge of the seal peeling start portion is in contact with a circumference of the inscribed ellipse.

3. 3. The pouch for use in a microwave oven according to claim 1, wherein the steam release seal portion has a seal strength equal to that of the peripheral seal portion.

4. 4. The pouch for use in a microwave oven according to claim 1, wherein the steam release seal portion is provided so as to be continuous with the peripheral seal portion.

Images