Bag for microwave oven

Abstract

The present invention aims to provide a microwave oven bag in which steam is easily discharged upon heating, and deformation of a portion provided with an automatic steam discharge mechanism after the contents are filled can be prevented. The above problem is solved by adopting the following configuration: in a microwave oven bag (100) having a rectangular shape in plan view and provided with an automatic steam discharge mechanism (120), the automatic steam discharge mechanism (120) is provided with a steam release portion (121) and a steam discharge seal portion (125) surrounding the periphery of the steam release portion (121), and when an inscribed ellipse (E) tangent to the inner ends of each side in the peripheral seal portion (115) of the bag is assumed, the steam discharge seal portion (125) is formed such that the outer periphery of the inscribed ellipse (E) is located within a width region of a seal peeling start portion (P) of the steam discharge seal portion (125) closest to a center point (O) of the accommodation portion (110) or in the vicinity of the seal peeling start portion.

Description

Technical Field

[0001] This invention relates to a microwave oven bag formed into a bag shape by thermally bonding overlapping laminated films and having an automatic steam venting mechanism that automatically releases internal steam when heated. Background Technology

[0002] Previously, the following packaged foods were available on the market: cooked or semi-cooked foods were placed inside bags formed by thermally bonding overlapping films, and the food was heated and cooked in a microwave oven before consumption.

[0003] Such microwave oven bags are usually equipped with an automatic steam venting mechanism that automatically releases internal steam during heating.

[0004] As an automatic steam discharge mechanism, there is a known mechanism that involves thermally bonding a portion of an overlapping laminated membrane to form an annular steam discharge seal, and then peeling off and retracting a portion of the steam discharge seal to discharge steam.

[0005] In such an automatic steam venting mechanism, the position of the steam venting seal affects the ease of steam venting during microwave heating and the deformation of the filled bag. If the peripheral seal retracts significantly during heating, the bag may break at the peripheral seal. Furthermore, significant deformation of the filled bag can negatively impact its transport through the filling equipment, insertion into the box, and its appearance.

[0006] For example, Patent Document 1 states that: the initial break point of the steam discharge seal is located on the circumference of or inside the circle inscribed in the center of the inner end of the peripheral seal of the two short sides.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent No. 4029590 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] However, as in Patent Document 1, it is clear that even when a steam discharge seal is provided, if the distance between the initial break point of the steam discharge seal and the center point of the bag housing is too large, it will be difficult to discharge steam and the seal will retract at the peripheral seal. If the distance between the initial break point of the steam discharge seal and the center point of the bag housing is too small, although it is easy to discharge steam, the deformation of the filled bag will also increase.

[0012] The present invention addresses the aforementioned problems and aims to provide a microwave oven bag that allows steam to escape easily during heating and prevents deformation of the portion equipped with an automatic steam venting mechanism after the contents are filled.

[0013] Technical solution

[0014] The microwave oven bag of the present invention is a microwave oven bag with a rectangular shape when viewed from above and equipped with an automatic steam venting mechanism. It solves the above-mentioned problems by adopting the following configuration: the automatic steam venting mechanism has a steam release part and a steam venting sealing part surrounding the steam release part. Assuming an inscribed ellipse tangent to the center of the inner end of each side of the peripheral sealing part of the bag, the steam venting sealing part is formed such that the outer periphery of the inscribed ellipse is located in or near the width region of the sealing peeling start portion of the steam venting sealing part closest to the center point of the receiving part.

[0015] Invention Effects

[0016] According to the invention of this solution 1, the steam discharge seal is formed such that the outer periphery of an inscribed ellipse tangent to the center of the inner end of each side of the peripheral seal of the bag is located within the width region of the seal peeling start portion closest to the center point of the receiving portion of the steam discharge seal or near the seal peeling start portion. Thus, while suppressing deformation of the portion equipped with the automatic steam discharge mechanism, such as warping, caused by the pressure of the contents after filling, the steam discharge seal can be peeled back by the force of the internal pressure extending from the center point side of the receiving portion without peeling off the peripheral seal, thereby allowing steam to be discharged.

[0017] According to the invention of this embodiment 2, the initial break point of the outer end of the steam discharge sealing part, which is the starting part of the sealing peeling, is tangent to the outer periphery of the inscribed ellipse. As a result, the initial break point can be made as close as possible to the center point of the receiving part, thereby further improving the steam discharge performance.

[0018] According to the invention of this embodiment 3, the steam discharge seal has the same sealing strength as the peripheral seal, thereby the steam discharge seal has the required sealing strength and is easier to peel off than the peripheral seal, and can reliably prevent the peripheral seal from peeling off before the sealing peeling begins on the steam discharge seal.

[0019] According to the invention of this embodiment 4, the steam discharge seal is configured to be continuous with the peripheral seal, thereby reliably preventing warping of the steam discharge seal after the contents are filled. Attached Figure Description

[0020] Figure 1This is a top view showing an example of the structure of a microwave oven bag according to the first embodiment of the present invention.

[0021] Figure 2 It means Figure 1 An enlarged view of a portion of the microwave oven bag shown.

[0022] Figure 3 It is a general representation Figure 1 A sectional view of part of the AA section.

[0023] Figure 4 This is a top view showing an example of the structure of a microwave oven bag according to the second embodiment of the present invention.

[0024] Figure 5 It is a general representation Figure 4 A sectional view of part of the BB section.

[0025] Figure 6 This is a diagram illustrating the formation location of the steam vent seal in the microwave oven bags made in Comparative Examples 1 to 6.

[0026] Figure 7 This is a diagram illustrating the formation location of the steam venting seal in the microwave oven bags made in Comparative Examples 7 to 12. Detailed Implementation

[0027] The microwave oven bag of the present invention is formed by heat-sealing stacked films into a bag shape, and has an automatic steam discharge mechanism that automatically releases steam inside the bag to the outside when heated.

[0028] As a laminated film, any laminated film can be formed by laminating known synthetic resin films, such as those made from synthetic resins containing thermoplastic resins like polyester, polypropylene, and polyamide, or by laminating coating films or vapor-deposited films that impart gas barrier and water barrier properties to these synthetic resin films, or by laminating paper or films containing metal layers onto such synthetic resin films.

[0029] The microwave oven bag of the present invention will now be described with reference to the accompanying drawings.

[0030] <First Implementation Method>

[0031] like Figures 1 to 3 As shown, the microwave oven bag (hereinafter referred to as "bag") 100 of the first embodiment of the present invention is configured as a flat bag with a rectangular shape when viewed from above.

[0032] The bag 100 is formed into a bag shape by forming a peripheral sealing portion 115 obtained by thermally bonding the periphery of a pair of overlapping surface side films 101 and back side films 102. The containing portion 110, which is surrounded by the peripheral sealing portion 115, contains food or other contents.

[0033] The peripheral sealing portion 115 includes a top sealing portion 116 obtained by thermally bonding the upper edges of the surface side film 101 and the back side film 102, a side sealing portion 117 obtained by thermally bonding the left and right side edges of the surface side film 101 and the back side film 102, and a bottom sealing portion 118 obtained by thermally bonding the lower edges of the surface side film 101 and the back side film 102.

[0034] To facilitate opening the bag 100 after heating, a notch 105 is provided at the predetermined opening position of the peripheral sealing part 115.

[0035] The bag 100 is equipped with an automatic steam discharge mechanism 120 that automatically releases steam from the containment section 110 to the outside when heated.

[0036] The automatic steam discharge mechanism 120 includes: a steam release section 121; and a steam discharge sealing section 125, which surrounds the steam release section 121 to isolate the steam release section 121 from the receiving section 110.

[0037] The vapor release section 121 is, for example, formed as an unsealed section in which the surface side film 101 and the back side film 102 are not thermally bonded.

[0038] It should be noted that the specific design of the vapor release section 121 is not limited to this. For example, the vapor release section 121 may be formed as a weak bonded section obtained by thermal bonding in a manner that makes the sealing strength lower than that of the peripheral sealing section 115 and the vapor discharge sealing section 125, or as a patterned bonded section obtained by knurling a pair of laminated films.

[0039] The steam release section 121 is provided with a steam discharge section 122 formed as a hole or slit.

[0040] The steam exhaust portion 122 is formed, for example, as a through hole with a flat elliptical opening shape and extends obliquely relative to the side edge of the bag. It should be noted that the steam exhaust portion 122 may be provided only on one of the surface side film 101 and the back side film 102 without having to be configured to penetrate both the surface side film 101 and the back side film 102.

[0041] The steam discharge seal 125 is formed by thermally bonding the surface-side film 101 and the back-side film 102, and is configured to gradually peel off and retract as the internal pressure of the receiving portion 110 increases during heating. The seal peeling start portion P, which begins to peel off due to the steam generated inside the bag 100, is the part of the outer edge of the steam discharge seal 125 closest to the center point O of the receiving portion 110, and the outer end of the seal peeling start portion P becomes the initial break point Q.

[0042] The steam discharge seal 125, when viewed from above, is formed in a semi-circular shape and is configured to be continuous at both ends with one of the side seals 117. It should be noted that the steam discharge seal 115 may also be configured to be continuous with the top seal 116, or it may be configured to be separate from the peripheral seal 115.

[0043] In this embodiment, a bag in which the vapor release section 121 is formed as an unsealed section is described. However, in the case of a bag without an unsealed section, the vapor release section 121 is set as the part of the vapor discharge section 122 that is closest to the center point O of the receiving section 110.

[0044] Furthermore, in the bag 100 of this embodiment, assuming an inscribed ellipse E tangent to the inner center positions of the periphery sealing portions 115 (i.e., the top sealing portion 116 and the bottom sealing portion 118) on the two short sides and the inner center positions of the periphery sealing portions 115 (i.e., the left and right side sealing portions 117, 117) on the two long sides, the steam discharge sealing portion 125 is positioned near the corners corresponding to the four corners of the bag 100, with the outer periphery of the inscribed ellipse E located within the width region of the sealing 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 becomes the center point O of the receiving portion 110.

[0045] When the bag 100 is heated, due to water vapor and other substances generated from the contents, the bag 100 expands radially from the center point O of the receiving portion 110 toward the peripheral sealing portion 115. However, since the outer shape of the bag 100 is rectangular when viewed from above, the space inside the receiving portion 110 expands in a roughly elliptical shape. It can be considered that the force of the internal pressure expanding from the center point O side of the receiving portion 110 acts on the surface of the receiving portion that expands in a roughly elliptical shape.

[0046] Furthermore, in the bag 100 of this embodiment, the steam discharge seal 125 is formed such that the outer periphery of the inscribed ellipse E, which is tangent to the center of the inner end of each side of the peripheral seal 115 of the bag 100, is located within the width region of the seal peeling start portion P. This allows the force of the internal pressure extending from the center point O side of the receiving portion 110 to effectively act on the seal peeling start portion P. Therefore, the steam discharge seal 125 can peel off from the seal peeling start portion P and retract without peeling off the peripheral seal 115, thereby allowing steam to be discharged through the steam discharge portion 122. Moreover, the distance L between the initial break point Q of the steam discharge seal 125, which is the outer end of the seal peeling start portion P, and the center point O of the receiving portion 110 can be sufficiently ensured. Therefore, deformation such as warping of the portion equipped with the automatic steam discharge mechanism 120 due to the pressure of the contents after filling can be suppressed.

[0047] Preferably, the steam discharge sealing portion 125 is configured such that the initial break point Q, which is the outer end of the sealing peeling start portion P, is tangent to the outer periphery of the inscribed ellipse E. This allows the initial break point Q in the sealing peeling start portion P to be as close as possible to the center point O of the receiving portion 110, thereby further improving the steam discharge performance.

[0048] The steam exhaust seal 125 has the same sealing strength as the peripheral seal 115 at room temperature, for example. Therefore, the steam exhaust seal 125 has the required sealing strength and is easier to peel off than the peripheral seal 115, reliably preventing the peripheral seal 115 from peeling off before the initial peeling portion P of the steam exhaust seal 125.

[0049] In the first embodiment described above, a microwave oven bag configured as a flat bag was explained, but the shape of the microwave oven bag is not limited to this, and it may also be configured as a stand-up pouch.

[0050] <Second Implementation Method>

[0051] like Figure 4 and Figure 5 As shown, the microwave oven bag (hereinafter referred to as "bag") 200 of the second embodiment of the present invention has a rectangular shape when viewed from above, and is configured as a stand-up bag with a flap 211 at the bottom.

[0052] The bag 200 is formed into a bag shape by heat-sealing the overlapping surface side film 201 and back side film 202 and the folded bottom film 203 sandwiched between the surface side film 201 and back side film 202 at a designated location to form a peripheral sealing part 215.

[0053] The peripheral sealing portion 215 includes a top sealing portion 216 obtained by thermally bonding the upper edges of the overlapping surface side film 201 and back side film 202, side sealing portions 217 and 217 obtained by thermally bonding the left and right side edges of the surface side film 201 and back side film 202, and a bottom sealing portion 218 obtained by thermally bonding the bottom end portions of each flap 204 and 204 of the bottom film 203 to the bottom end portions of the surface side film 201 and back side film 202 respectively.

[0054] In the bag 200 of this embodiment, assuming an inscribed ellipse E tangent to the inner center of the periphery sealing portions 215 (top sealing portion 216 and bottom sealing portion 218) of the two short sides and the inner center of the periphery sealing portions 215 (left and right side sealing portions 217, 217) of the two long sides, the steam discharge sealing portion 125 in the automatic steam discharge mechanism 120 is positioned near the corners corresponding to the four corners of the bag 200, with the outer periphery of the inscribed ellipse E 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 becomes the center point O of the receiving portion 210. Furthermore, the automatic steam discharge mechanism 120 has the same configuration as the automatic steam discharge mechanism 120 of the bag 100 of the first embodiment.

[0055] In the bag 200 of the second embodiment, from the viewpoint of improving steam discharge performance, it is preferable that the steam discharge sealing part 125 is configured such that the initial break point Q, which is the outer end of the sealing peeling start part P, is tangent to the outer periphery of the inscribed ellipse E.

[0056] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments. Various design changes can be made without departing from the present invention as described in the claims.

[0057] For example, the steam discharge seal can be independently located inside the outer edge seal without needing to be continuous with the peripheral seal. Furthermore, the steam discharge seal can be formed into other shapes such as a rectangular ring, and its size can be appropriately selected.

[0058] Furthermore, when the steam exhaust section is formed as a hole, the shape of the hole opening can be any shape, such as circular, oblong, triangular, quadrilateral, trapezoidal, or rice ball-shaped, without being elliptical, and its size can also be appropriately selected. Alternatively, the steam exhaust section can be formed as a slit, and the shape of the slit can be any shape, such as semicircle, arc, unequal sign, or straight line, and its size can also be appropriately selected.

[0059] Example

[0060] The present invention will be further described below through examples, but the specific examples below do not limit the present invention.

[0061] <Example 1>

[0062] Reference Figures 1 to 3 The configuration shown indicates that a microwave oven bag of the present invention (hereinafter referred to as "bag 1") was manufactured, wherein the steam exhaust sealing portion is formed such that the outer end of the sealing peeling start portion is tangent to the outer periphery of the following inscribed ellipse: an inscribed ellipse tangent to the center of the inner end of each side in the peripheral sealing portion of the bag.

[0063] The steam discharge seal is formed at the following positions: the angle θ between the straight line connecting the center point of the receiving part and the center of the inner end of the top seal and the straight line connecting the center point of the receiving part and the outer end of the seal peeling start part is 48°, and the distance L from the center point of the receiving part to the initial break point at the outer end of the seal peeling start part is 68mm.

[0064] The steam discharge seal is formed as a semi-circular ring with an inner diameter of 11 mm and an outer diameter of 18 mm. At room temperature, the sealing strength of the steam discharge seal is equal to that of the peripheral seal. Furthermore, the width of the peripheral seal is 6 mm.

[0065] Fill bag 1 with 150g of water and visually inspect the corners of the bag where the steam escape seal is formed to check for deformation.

[0066] In addition, the bag 1 filled with contents was heated using a microwave oven with a rated output of 600W, and the steaming status was checked. In the evaluation, the case where there was no retraction of the peripheral seal and the bag did not break was marked as "0", the case where the bag did not break but the peripheral seal retracted was marked as "Δ", and the case where the bag broke was marked as "×".

[0067] The results are shown in Table 1 below.

[0068] Examples 2 to 9

[0069] Eight microwave oven bags (hereinafter referred to as "bag 2" to "bag 9") were manufactured. Except for the changes made to one or both of the bag's shape and the location of the steam exhaust seal according to Table 1 below, these eight microwave oven bags have the same structure as bag 1 manufactured in Example 1.

[0070] For each of the eight types of bags 2 to 9, the corners of the bags were visually inspected for deformation after the contents were filled, using the same method as in Example 1, and the steaming process during heating was also checked. The results are shown in Table 1 below.

[0071] <Comparative Examples 1 to 6>

[0072] Six types of microwave oven bags for comparison were produced (hereinafter referred to as "Comparison Bag 1" to "Comparison Bag 6"), in addition to the following: Figure 6 The six comparative microwave oven bags have the same configuration as bag 1 made in Example 1, except that the steam exhaust seal is formed such that the initial break point Q is located on the circumference of the inscribed circle R1 that is tangent to the center of the inner end of the peripheral seal of the two short sides of the bag, and the configuration is modified according to Table 2 below, with one or both of the outer shape of the bag and the formation position of the steam exhaust seal being changed. Figure 6 The area S enclosed by the circular dashed line is a schematic representation of the location where the steam discharge seal is formed.

[0073] For each of the six comparative bags 1 to 6, the same method as in Example 1 was used to visually observe whether the corners of the bags were deformed after the contents were filled, and to check the steaming process during heating. The results are shown in Table 2 below.

[0074] <Comparative Examples 7 to 12>

[0075] Six types of microwave oven bags for comparison were produced (hereinafter referred to as "Comparison Bags 7" to "Comparison Bags 12"), in addition to the following: Figure 7 The six comparative microwave oven bags have the same configuration as bag 1 made in Example 1, except that the steam exhaust seal is formed such that the initial break point Q is located on or near the circumference of the inscribed circle R2 that is tangent to the center of the inner end of the peripheral seal of the two long sides of the bag, and one or both of the outer shape of the bag and the formation position of the steam exhaust seal are changed according to Table 2 below. Figure 7 The area S enclosed by the circular dashed line is a schematic representation of the location where the steam discharge seal is formed.

[0076] For each of the six comparative bags 7 to 12, the same method as in Example 1 was used to visually observe whether the corners of the bags were deformed after the contents were filled, and to check the steaming status during heating. The results are shown in Table 2 below.

[0077] [Table 1]

[0078]

[0079] [Table 2]

[0080]

[0081] As shown in the results above, it has been confirmed that bags 1 to 9 according to the present invention can be steamed through the steam discharge seal without warping at the corners of the bag after the contents are filled and without breaking during microwave heating. Furthermore, it has been confirmed that when the outer diameter shape has a smaller ellipticity (inscribed ellipse), forming the steam discharge seal at a position where the distance from the center point of the receiving portion to the outer end of the seal peeling start portion is smaller is more advantageous for safe steaming.

[0082] On the other hand, it was confirmed that although the warping of the corners of the bag could be suppressed after the contents were filled in the comparative bags 1 to 6, the bags would break from the side seal when heated in a microwave oven.

[0083] Furthermore, it was confirmed that in comparative bags 7 to 12, although steam could be released from the sealed part without breaking during microwave heating, noticeable warping occurred at the corners of the bag after the contents were filled.

[0084] Explanation of reference numerals in the attached figures

[0085] 100, 200: Microwave oven bags;

[0086] 101, 201: Surface side film;

[0087] 102, 202: Backside film;

[0088] 203: Base film;

[0089] 204: Folded piece;

[0090] 105: Gap;

[0091] 110, 210: Reception area;

[0092] 211: Lapel;

[0093] 115, 215: Peripheral sealing part;

[0094] 116, 216: Top sealing part;

[0095] 117, 217: Side sealing parts;

[0096] 118, 218: Bottom sealing part;

[0097] 120: Automatic steam discharge mechanism;

[0098] 121: Steam release section;

[0099] 122: Steam exhaust section;

[0100] 125: Steam discharge sealing section;

[0101] E: Inscribed ellipse;

[0102] O: The center point of the accommodating part;

[0103] P: The beginning of the seal peeling process;

[0104] Q: Initial break point;

[0105] R1: Inscribed circle;

[0106] R2: Inscribed circle;

[0107] S: Location where the steam discharge seal is formed.

Claims

1. A microwave oven bag, which, when viewed from above, has a rectangular shape and an automatic steam venting mechanism, characterized in that, The automatic steam discharge mechanism includes a steam release section and a steam discharge sealing section surrounding the steam release section. Assuming an inscribed ellipse tangent to the center of the inner end of each side of the peripheral seal of the bag, the steam discharge seal is formed such that the outer periphery of the inscribed ellipse is located within or near the width region of the seal peeling start portion closest to the center point of the receiving portion of the steam discharge seal. The inscribed ellipse has a minor axis and a major axis, and the ratio of the minor axis to the major axis is 0.6 to 0.

97.

2. The microwave oven bag according to claim 1, characterized in that, The steam discharge seal is formed such that the outer end of the seal peeling start portion is tangent to the outer periphery of the inscribed ellipse.

3. The microwave oven bag according to claim 1 or 2, characterized in that, The steam discharge seal has the same sealing strength as the peripheral seal.

4. The microwave oven bag according to claim 1 or 2, characterized in that, The steam discharge seal is configured to be continuous with the peripheral seal.

5. The microwave oven bag according to claim 3, characterized in that, The steam discharge seal is configured to be continuous with the peripheral seal.

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