Packaging bag

Abstract

To provide a packaging bag allowed to prevent vapor from leaking from other points than a predetermined one during heating with a microwave oven.SOLUTION: A packaging bag according to one embodiment, which is of a pillow type having a back-sealed portion, comprises a sealed portion formed at both ends in a first direction, a gazette portion and a vapor release-finished portion. A first area, including an intersection of a fold line in the gazette portion and a side inner of the sealed portion out of inner surfaces opposed at both ends in the first direction of the gazette portion, is sealed with a first vanish having seal-ability under an environment of 70°C, having a load index X1 at an intersection defined by Expression (1A) of 3000 or greater. X1=(R-G+t1)×W...(1A) R=2×(W-2×s)÷π...(2) In Expressions (1A) and (2), W is a length in the first direction of the packaging bag, G is a length in a second direction of the gazette portion, s is a length in the first direction of the sealed portion, and t1 is a length in the second direction of the first area.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a packaging bag.

Background Art

[0002] There is an increasing need for food packaging that can be heated in a microwave oven and then eaten. From the perspective of consumer convenience, packaging bags that can be directly heated in a microwave oven (see, for example, Patent Documents 1 and 2) are known. Such packaging bags that are heated in a microwave oven are configured to automatically release the internal pressure to the outside of the packaging bag when the internal pressure reaches a certain pressure in order to prevent the packaging bag from bursting due to expansion caused by an increase in internal pressure due to microwave heating.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The packaging bag described in Patent Document 2 is a pillow-type packaging bag, and is configured such that a steam vent for discharging steam generated during range heating is formed during range heating. The above packaging bag has a center seal portion, first and second seal portions formed at both ends orthogonal to the center seal portion, and a gusset portion formed by folding parallel to the center seal portion. Since the packaging bag has a gusset portion, there are intersections between the folding line of the gusset portion (the deepest part of the gusset portion) and the inner side edges of the first and second seal portions respectively. Therefore, when the packaging bag expands due to range heating, due to the load generated at the above intersections, unintended seal retraction occurs near the intersections, and as a result, steam may escape from a location different from the desired steam vent, or the contents may spurt out.

[0005] One aspect of the present disclosure aims to provide a packaging bag capable of preventing steam from leaking from locations other than a desired location during microwave heating.

Means for Solving the Problems

[0006] [1] The packaging bag according to one aspect of the present disclosure is a pillow-type packaging bag for microwave heating having a back seal portion, and includes seal portions formed at both ends in a first direction which is the extending direction of the back seal portion, a gusset portion formed on one side in a second direction orthogonal to the first direction, and a steam venting portion formed in a region other than the gusset portion for venting internal steam during microwave heating. In the gusset portion, a first region including intersections of folding lines in the gusset portion and inner sides of the seal portions on the inner surfaces facing each other at both ends in the first direction is sealed with a first varnish having sealing properties in a 70°C environment. When the load index X1 at the intersection is defined by formula (1A), X1 is 3000 or more. X1 = (R - G + t1) × W ··· (1A) R in formula (1A) is defined by formula (2). R = 2 × (W - 2 × s) ÷ π ··· (2) In formulas (1A) and (2), W is the length of the packaging bag in the first direction, G is the length of the gusset portion in the second direction, s is the length of the seal portion in the first direction, and t1 is the length of the first region in the second direction.

[0007] In the packaging bag described in [1] above, since it has a steam venting portion, when the packaging bag is heated in a microwave oven, excess steam can be vented from the steam venting portion. The packaging bag has a gusset portion. In the packaging bag, the load index X1 at the intersection is 3000 or more. Therefore, when heated in a microwave oven, seal recession at the intersection is prevented. Therefore, since the packaging bag does not open unintentionally at the position of the intersection, in the configuration of the packaging bag, steam leakage from locations other than the steam venting portion, which is the desired location, can be prevented.

[0008] [2] In the packaging bag described in [1] above, the second region adjacent to the first region in the second direction may be sealed with a second varnish having sealability at room temperature or lower. In the packaging bag of this [2], for example, when transporting or storing, damage near the intersection is less likely to occur.

[0009] [3] In the packaging bag described in [1] or [2] above, the gusset portion has a pair of gusset pieces extending along the first direction, both ends of each of the pair of gusset pieces in the first direction are sealed at the seal portion, and the seal portions in each of the pair of gusset pieces may be sealed with the first varnish.

[0010] [4] Another example of the packaging bag according to the present disclosure is a pillow-type packaging bag for microwave heating having a back sticker seal portion, and seal portions formed at both ends in the first direction which is the extending direction of the back sticker seal portion, a gusset portion formed on one side in the second direction orthogonal to the first direction, and a steam vent processing portion formed in a region other than the gusset portion for venting internal steam during microwave heating. When the load index X2 at the intersection of the fold line in the gusset portion and the inner side edge of the seal portion is defined by the formula (1B), X2 is 3000 or more. X2 = (R - G + t1) × W ··· (1B) R in the formula (1B) is defined in the formula (2). R = 2 × (W - 2 × s) ÷ π ··· (2) In the formulas (1B) and (2), W is the length of the packaging bag in the first direction, G is the length of the gusset portion in the second direction, and s is the length of the seal portion in the first direction.

[0011] In the packaging bag described in [4] above, since it has a steam venting processed portion, when the packaging bag is heated in a microwave oven, excess steam can be vented from the steam venting processed portion. The packaging bag has a gusset portion. In the packaging bag, the load index X2 at the above intersection is 3000 or more. Therefore, when heated in a microwave oven, seal recession at the intersection is prevented. Therefore, since the packaging bag does not accidentally open at the position of the intersection, in the configuration of the packaging bag, steam leakage from locations other than the steam venting processed portion, which is the desired location, can be prevented.

Advantages of the Invention

[0012] According to the present disclosure, it is possible to provide a packaging bag capable of preventing steam leakage from locations other than a desired location during microwave heating.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same elements are denoted by the same reference numerals, and redundant descriptions are omitted. The dimensional ratios in the drawings do not necessarily match those in the description.

[0015] FIG. 1 is a front view schematically showing a packaging bag according to the present embodiment. FIG. 2 is a rear view of the packaging bag shown in FIG. 1. FIG. 3 is a schematic sectional view taken along line III-III of FIG. 1.

[0016] In the following description, the x-direction (first direction) and y-direction (second direction) shown in FIGS. 1 to 3 may be used. The x-direction and y-direction are orthogonal. FIGS. 1 and 2 schematically show the state in which the packaging bag 1 is flat-folded without the contents being accommodated in order to explain the dimensions of the packaging bag 1. The examples of the dimensions in the following description are based on the state in which the packaging bag 1 is flat-folded without the contents being accommodated.

[0017] The packaging bag 1 is a pillow-type packaging bag for microwave heating for accommodating contents (not shown). The contents accommodated in the packaging bag 1 are, for example, foods that can be heated in a microwave oven. The packaging bag 1 is, for example, a bag for foods that are transported or stored in an environment of 5°C or lower (refrigerated or frozen). In the present embodiment, the packaging bag 1 is, for example, a primary food packaging material for the purpose that after a consumer takes out the packaging bag 1 from a refrigerator or freezer, the packaging bag 1 is directly put into a microwave oven and the contents are heated by the microwave oven.

[0018] The packaging bag 1 is composed of a film F. The film F is a laminated film in which a sealant layer (inner layer) and an outer layer are laminated. An example of the thickness of the film F is 50 μm or more and 90 μm or less.

[0019] The sealant layer is the layer located inside in the packaging bag 1. Examples of the material of the sealant layer are linear low density polyethylene (LLDPE), low density polyethylene (LDPE), and the like. An example of the thickness of the sealant layer is 30 μm or more and 80 μm or less, and more preferably 40 μm or more and 60 μm or less.

[0020] The outer layer is a layer laminated on the sealant layer. The outer layer is the layer located on the outside in the packaging bag 1. An example of the thickness of the outer layer is 12 μm or more and 30 μm or less. The outer layer is, for example, a resin layer. Examples of the material of the outer layer include polyethylene terephthalate (PET), nylon (or polyamide), polybutylene terephthalate (PBT), etc. The outer layer may be a uniaxially or biaxially stretched film. For example, the outer layer may be a biaxially stretched PET film or a biaxially stretched nylon film (hereinafter sometimes referred to as an "ONY film"). The outer layer may be a laminate of a plurality of resin layers. When the outer layer has a plurality of resin layers, examples of the materials of the plurality of resin layers may be PET, nylon (or polyamide), PBT, etc. described above. The materials of the plurality of resin layers may be the same or different.

[0021] The packaging bag 1 is configured by forming the above film F into a pillow shape so as to form an accommodation space 7 (see FIG. 3) for accommodating the contents. The packaging bag 1 has a rectangular shape in plan view. The packaging bag 1 has side edges 1a and 1b extending in the x direction. The side edge 1b is located opposite to the side edge 1a in the y direction. The packaging bag 1 has side edges 1c and 1d extending in the y direction. The side edge 1c is located opposite to the side edge 1d in the x direction.

[0022] An example of the length W [mm] between the side edges 1a and 1b is 170 mm or more and 230 mm or less. The length W is the outer dimension of the packaging bag 1 in the x direction. An example of the length H [mm] between the side edges 1c and 1d is 120 mm or more and 185 mm or less. The length H is the outer dimension of the packaging bag in the y direction. The ratio (H / W) of the length H to the length W is, for example, 0.65 or more and 1.09 or less. The ratio H / W corresponds to the aspect ratio of the outer dimensions of the packaging bag 1.

[0023] The packaging bag 1 has a back seal portion 2 extending in the x direction. The back seal portion 2 is formed by heat-sealing the inner surfaces (sealant layer surfaces) after both ends of the film F bent into a tubular shape are joined in a clasped shape.

[0024] In this embodiment, the surface of the packaging bag 1 on which the back sticker seal portion 2 is formed is the "back surface" of the packaging bag 1, and the surface opposite to the back sticker seal portion 2 is the "front surface" of the packaging bag 1. The back surface of the packaging bag 1 is the surface located on the tray side in the microwave oven when the packaging bag 1 is placed in the microwave oven.

[0025] The back sticker seal portion 2 is provided at the center in the y direction in the packaging bag 1. The fact that the back sticker seal portion 2 is formed at the center means that the length between the connection portion of the back sticker seal portion 2 and the back surface (the end opposite to the free end of the back sticker seal portion 2) and the side 1a (or side 1b) is approximately H / 2.

[0026] Furthermore, a gusset portion 3 (or a machi portion) is formed on one side in the y direction of the packaging bag 1. The gusset portion 3 is formed by folding one side of the film F bent in a cylindrical shape inward. The gusset portion 3 extends in the x direction and has a pair of opposing gusset pieces 31, 32. As shown in FIG. 3, the cross-sectional shape orthogonal to the extending direction (x direction) of each gusset piece 31, 32 is V-shaped. That is, the gusset pieces 31, 32 are the portions where the film F is bent in a V shape. An example of the length G [mm] of the gusset portion 3 in the y direction is 25 mm or more and 45 mm or less. The length G is the distance between the line located deepest in the gusset portion 3 (hereinafter referred to as the "fold line 3a") and the side 1b. The fold line 3a is the boundary line between the region of the gusset portion 3 and the other region in the packaging bag 1 and is also the portion connecting the pair of gusset pieces 31, 32.

[0027] Both ends of the packaging bag 1 in the x direction are sealed. Therefore, the packaging bag 1 has a pair of sealing portions 4 facing each other in the x direction. When distinguishing between the pair of sealing portions 4, one of the pair of sealing portions 4 is referred to as the sealing portion 4A, and the other is referred to as the sealing portion 4B. The sealing portion 4A is, for example, an end seal portion, and the sealing portion 4B is a top seal portion. Both ends of each of the pair of gusset pieces 31, 32 of the gusset portion 3 are also heat-sealed by the sealing portion 4. That is, both ends of each of the pair of gusset pieces 31, 32 also have the sealing portion 4.

[0028] An example of the width s [mm] of the sealing portion 4 is 5 mm or more and 15 mm or less. The width s is the length between each of the side edges 1c and 1d and the inner side edge 4a of the sealing portion 4. Unless otherwise specified, the widths s of the sealing portion 4A and the sealing portion 4B are the same.

[0029] As shown in FIG. 1, a steam venting portion 5 is formed on the front surface of the packaging bag 1. The steam venting portion 5 is formed, for example, along the x direction at the central portion in the y direction. The steam venting portion 5 has a function of discharging excess water vapor generated from the contents when the packaging bag 1 is heated in a microwave oven. The steam venting portion 5 is a portion that communicates the accommodation space with the outside of the packaging bag 1 to exhaust the steam inside the packaging bag 1 when the internal pressure of the packaging bag 1 exceeds a predetermined pressure during microwave heating. The steam venting portion 5 is configured such that when the pressure inside the packaging bag 1 exceeds the predetermined pressure, the steam venting portion 5 selectively breaks to form a steam port. An example of the predetermined pressure is 0.113 MPa. The steam venting portion 5 can be formed, for example, by applying a notch process to the film F. The notch process may be, for example, a process using a laser beam.

[0030] The packaging bag 1 will be described from another perspective. The packaging bag 1 is configured such that the film F is bent into a tubular shape, has a gusset portion 3, and the film F is sealed so as to form an accommodation space 7. Specifically, the packaging bag 1 has a tubular portion 10. The tubular portion 10 has the above-described back sticker seal portion 2. Both ends of the tubular portion 10 are sealed by seal portions 4 (seal portion 4A and seal portion 4B). Further, in the tubular portion 10, a gusset portion 3 is formed on one side in the y direction.

[0031] FIG. 4 is an enlarged view of region A in FIG. 2, and is an enlarged view of region A on the seal portion 4A side. Hereinafter, while using FIG. 4, region A on the seal portion 4A side will be described. However, the region corresponding to region A on the seal portion 4B side also has the same configuration as region A.

[0032] In the packaging bag 1, the inner surface of the end portion of the gusset portion 3 in the x direction may be sealed with a first varnish. That is, the inner surfaces of the pair of gusset pieces 31, 32 may be sealed with a first varnish at the end portion of the gusset portion 3 in the x direction. More specifically, the inner surfaces of the pair of gusset pieces 31, 32 that face each other in the seal portion 4 may be sealed with a first varnish. The inner surfaces of the seal portion 4 among the gusset pieces 31, 32 are surfaces that face each other in the seal portion 4 formed on each of the gusset pieces 31, 32. The region sealed with the first varnish (in other words, the region where the first varnish is applied) is referred to as a first varnish region (first region) 21. In FIG. 4, the first varnish region 21 is indicated by hatching.

[0033] The first varnish region 21 is formed such that the intersection 6 between the inner side edge 4a of the seal portion 4 (seal portion 4A) and the folding line 3a is sealed with the first varnish. In one embodiment, the first varnish region 21 is a region having a length t1 extending from the folding line 3a toward the side edge 1b side, and also has a length t3 extending inward from the side edge 1c (toward the side edge 1d). An example of the length t1 of the first varnish region 21 in the y direction may be greater than 0 mm and equal to or less than 45 mm. The length t3 may be equal to or greater than the width s. The first varnish region 21 may be formed to extend slightly beyond the inner side edge 4a of the seal portion 4 (seal portion 4A). The upper limit of the length t3 may be any length that can ensure the function of the gusset portion 3 of increasing the internal volume of the packaging bag 1, for example, it may be equal to or less than 1.3s.

[0034] The first varnish is a varnish having sealing properties in an environment of 70°C. Therefore, the first varnish is a heat-resistant type of varnish. For example, the first varnish may be a varnish that satisfies the following conditions a1, a2, and a3. (a1) Sealing strength at room temperature (23°C) environment: 2.0 N / 15 mm or more (a2) Sealing strength at 70°C environment (hot environment): 2.0 N / 15 mm or more (a3) Sealing strength at 0°C environment (cold environment): less than 1.0 N / 15 mm

[0035] An example of the upper limit of the sealing strength in the above conditions a1 and a2 is 6.0 N / 15 mm, and in the above condition a3, the sealing strength may be greater than 0 N / 15 mm.

[0036] The above-mentioned seal strength may be the strength measured by a method conforming to JIS Z0238. Specifically, after sealing a sample film corresponding to the film F with the first adhesive, a test piece with a width of 15 mm is cut out. For the test piece composed of the two sealed sample films, the measured strength may be adopted as the seal strength by performing a T-peel test under a tensile condition of 300 mm / min. When the film F is a laminated film of an LLDPE film and a PET film, a laminate obtained by applying the first adhesive on the surface of the PET film and joining the PET films together may be used as the test piece.

[0037] As shown in FIG. 4, the packaging bag 1 may have a second adhesive region (second region) 22 outside the first adhesive region 21 (on the side of the side 1b). In FIG. 4, the second adhesive region 22 is shown with hatching different from that of the first adhesive region 21. The second adhesive region 22 is a region where the second adhesive is applied and the x-direction ends of the pair of gusset pieces 31, 32 are sealed. That is, the second adhesive region 22 is a region where the inner surfaces of the pair of gusset pieces 31, 32 are sealed with the second adhesive at the x-direction ends of the gusset portion 3. The second adhesive region 22 is adjacent to the first adhesive region 21 on the side of the side 1b. The length t2 [mm] in the y direction of the second adhesive region 22 may be any length that satisfies the following formula. Usually, t2 is shorter than t1. t1 + t2 ≤ G The length of the second adhesive region 22 in the x direction may be the same as or different from the length of the first adhesive region 21 in the x direction.

[0038] The second adhesive is an adhesive having sealability in an environment of 0°C. Therefore, the second adhesive is a cold-resistant type of adhesive. For example, the second adhesive may be an adhesive that satisfies the following conditions b1, b2, and b3. The method for measuring the seal strength of the second adhesive is the same as that of the first adhesive. (b1) Seal strength at room temperature (23°C) environment: 2.0 N / 15 mm or more (b2) Seal strength at 70°C environment (hot environment): less than 1.0 N / 15 mm (b3) Sealing strength under 0°C environment (cold environment): 1.0 N / 15 mm or more

[0039] An example of the upper limit of the sealing strength under the above conditions (b1) and (b3) is 5.0 N / 15 mm. Under the above condition (b2), the sealing strength may be greater than 0 N / 15 mm.

[0040] Although the area A on the side of the sealing part 4A has been described with reference to FIG. 4, as described above, the area corresponding to the area A on the side of the sealing part 4B also has the same configuration as the area A.

[0041] The packaging bag 1 is configured to satisfy condition I. <Condition I> The load index X1 at the intersection 6 between the inner side edge 4a of the sealing part 4 and the folding line 3a is 3000 or more.

[0042] The load index X1 in condition I is an index defined by formula (1A). X1 = (R - G + t1) × W ··· (1A) R in formula (1A) is defined by formula (2). "π" in formula (2) is the pi. R = 2 × (W - 2 × s) ÷ π ··· (2)

[0043] R shown in formula (2) is the theoretical body circumference radius of the accommodation space 7 when it is assumed that the packaging bag 1 expands into a cylindrical shape as shown in FIG. 5 by being heated in a microwave oven. FIG. 5 is a schematic cross-sectional view along the V-V line when it is assumed that the packaging bag 1 in FIG. 1 expands into a cylindrical shape. The V-V line in FIG. 1 is located approximately at the center in the y direction of the packaging bag 1. In FIG. 5, the illustration of the back adhesive sealing part 2 is omitted.

[0044] The above load index X1 may be 4000 or more.

[0045] If the packaging bag 1 is configured to satisfy condition II, it may not have the first varnish area 21. Note that not having the first varnish area 21 corresponds to the length t1 shown in FIG. 4 being 0. <Condition II> The load index X2 of intersection point 6 is 3000 or more.

[0046] The load index X2 in Condition II is an index defined by Equation (1B). X2 = (R - G) × W ··· (1B) R in Equation (1B) is the R defined by the above Equation (2).

[0047] The above load index X2 may be 4000 or more.

[0048] As shown in FIGS. 1 and 2, intersection points 6 exist on both sides of the gusset portion 3. That is, in the form shown in FIGS. 1 and 2, there are two intersection points 6 on the packaging bag 1. The packaging bag 1 is configured such that the above Condition I or Condition II is satisfied at each of the two intersection points 6. Specifically, each parameter included in Equation (1A) or Equation (1B) and Equation (2) is set so as to satisfy Condition I or Condition II.

[0049] The above packaging bag 1 is manufactured, for example, as follows. Prepare a rectangular film F in which a degassing processing portion 5 is formed. Bend the film F into a cylindrical shape. After bringing both ends of the film F bent into a cylindrical shape into contact with each other in an inner surface-to-inner surface manner in a clasped shape, form a back seal portion 2 by heat-sealing the both ends to obtain a cylindrical body. In the cylindrical body, with one side parallel to the back seal portion 2 as a folding line 3a, fold a part of the cylindrical body inward to form a gusset portion 3. Seal one end of the two ends in the x direction of the cylindrical portion 10 obtained by forming the gusset portion 3 to form a seal portion 4A (seal portion 4). Then, put the contents into the cylindrical portion 10 and seal the other end of the two ends in the x direction of the cylindrical portion 10 to form a seal portion 4B (seal portion 4). In the step of forming the seal portions 4A and 4B, seal portions 4 are also formed at both ends of a pair of gusset pieces 31 and 32 of the gusset portion 3, respectively.

[0050] In the form where the packaging bag 1 has the first adhesive region 21, after applying the first adhesive to the regions that are to become the seal portions 4 at both ends of the pair of gusset pieces 31 and 32, the inner surfaces of the pair of gusset pieces 31 and 32 are sealed in the same process as the process of forming the seal portions 4A and 4B. In the form where the second adhesive region 22 is further formed, after applying the second adhesive in addition to the application of the first adhesive, the inner surfaces of the pair of gusset pieces 31 and 32 are sealed.

[0051] Since the above-mentioned packaging bag 1 has the steam venting portion 5, excessive steam can be discharged from the steam venting portion 5 when heated in a microwave oven. Therefore, in the packaging bag 1, it is possible to prevent the packaging bag 1 from bursting during microwave heating, so the contents in the packaging bag 1 can be heated in a microwave oven.

[0052] The packaging bag 1 has the gusset portion 3. Therefore, the content volume of the packaging bag 1 can be increased compared to the case where it does not have the gusset portion 3.

[0053] In the form where the packaging bag 1 has the first adhesive region 21, the packaging bag 1 satisfies condition I, and in the form where the packaging bag 1 does not have the first adhesive region 21, the packaging bag 1 satisfies condition II. Therefore, even if the packaging bag 1 has the gusset portion 3, it is possible to prevent seal recession from occurring at the intersection 6 during microwave heating. That is, in the packaging bag 1, it is prevented that locations other than the steam vent formed at the steam venting portion 5 open during microwave heating, allowing steam to escape or the contents to spurt out.

[0054] When the packaging bag 1 has the first adhesive region 21, the vicinity of the intersection 6 is sealed with a heat-resistant type of first adhesive. Therefore, the load on the intersection 6 during microwave heating can be reduced compared to the case where it does not have the first adhesive region 21.

[0055] When the packaging bag 1 has the second adhesive region 22, near the intersection 6 in the gusset portion 3 is sealed at room temperature or below. Therefore, damage near the intersection 6 can be prevented even during transportation or the like. In particular, when the packaging bag 1 is for food that is transported, stored, etc. in an environment of 5°C or lower (refrigerated or frozen), it is effective to provide the second adhesive region 22.

[0056] [Experimental Example] Next, an experimental example regarding the packaging bag 1 will be described. For the sake of convenience in the description, in the description of the experimental example, even when the above conditions I and II are not satisfied, elements corresponding to the elements described in the above embodiment are given the same reference numerals as in the case of the embodiment, and duplicate descriptions are omitted.

[0057] In the experimental example, samples 1 to 19 of the packaging bags shown in FIGS. 1 and 2 were manufactured. The layer configuration of the film F used for manufacturing samples 1 to 19 was as follows. (Layer Configuration of Film F) First PET Film / Second PET Film / LLDPE Film

[0058] In the above layer configuration, the laminated portion of the first PET film and the second PET film was the outer layer of the film F, and the LLDPE film was the sealant layer of the film F. The thickness of the first PET film and the second PET film was 12 μm, and the thickness of the LLDPE film was 40 μm.

[0059] Samples 1 to 19 were pillow-shaped packaging bags shown in FIGS. 1 and 2, and had a back sticker seal portion 2, a pair of seal portions 4, and a gusset portion 3. The seal portion 4 was orthogonal to the back sticker seal portion 2, and the gusset portion 3 extended in the extending direction of the back sticker seal portion 2.

[0060] As shown in Fig. 1, Samples 1 to 19 had a steam venting portion 5 at the central part in the y direction. The steam venting portion 5 was arranged at a position of H / 2 [mm] from the side 1a in the y direction. The steam venting portion 5 was a linear scratch processing portion along the x direction and was formed by scratch processing using a laser beam along the x direction. The center of the steam venting portion 5 in the x direction was located at the central part of the packaging bag in the x direction (W / 2 [mm] from the side 1c or side 1d), and the length of the steam venting portion 5 in the x direction was 50 mm.

[0061] As described with reference to Fig. 4, Samples 3 to 10, 12 to 14, and 16 to 19 had a first varnish region 21. The first varnish applied to the first varnish region 21 was TM-4813 manufactured by Toyo Morton Co., Ltd. The first varnish region 21 had the same conditions in Samples 3 to 10, 12 to 14, and 16 to 19 except for the difference in the length t1 (see Fig. 4) in the y direction. The length t3 of the first varnish region 21 was 12 mm.

[0062] In Samples 3 to 10, 12 to 14, and 16 to 19 having the first varnish region 21, as described with reference to Fig. 4, a second varnish region 22 was provided adjacent to the first varnish region 21. The second varnish applied to the second varnish region 22 was Q202PPNT-S Seal C manufactured by Toyo Ink Co., Ltd. The lengths t2 and t3 (see Fig. 4) of the second varnish region 22 were 10 mm and 12 mm, respectively.

[0063] In Samples 1 to 19, the lengths G [mm], H [mm], W [mm], and width s [mm] shown in Figs. 1 and 2 and the length t1 [mm] shown in Fig. 4 were as shown in the chart in Fig. 9. The fact that the length t1 was 0 meant that the samples (specifically, Samples 1, 2, 11, and 15) did not have the first varnish region 21.

[0064] In Fig. 9, "W - 2×s" (mm) corresponded to the inner dimension of the accommodation space 7 in the x direction in Samples 1 to 19, and "H / W" corresponded to the aspect ratio of the outer dimensions of Samples 1 to 19.

[0065] In Fig. 9, the calculated results of the theoretical barrel circumference radius R calculated based on formula (2) and the load index X at the intersection 6 are also shown. When the length t1 is not zero, the load index X is X1 calculated based on formula (1A), and when the length t1 is zero, it is the value calculated based on formula (1B).

[0066] When manufacturing the film F into the packaging bags of Samples 1 to 19, the sealing conditions of the seal portion 4 and the first varnish region 21 were made common with the settings of 170 °C, 1.0 second, and a cooling temperature of 70 °C using OPL-600-10 manufactured by Fuji Electric Co., Ltd.

[0067] In the experimental examples, Samples 1 to 19 containing the contents were manufactured and heated by a microwave oven. The heating conditions were 500 W and 1 minute 30 seconds. The sealing state of the intersection 6 after the above microwave oven heating was evaluated.

[0068] Specifically, as shown in Fig. 6, the case where the first varnish region 21 remains substantially the same as before heating was defined as Evaluation A+. As shown in Fig. 7, the case where seal recession occurs in the first varnish region 21 but the seal recession has not reached the intersection 6 (that is, the first varnish remains at the intersection 6) was defined as Evaluation A. In Fig. 7, the dashed-dotted line region indicates the first varnish region 21 before microwave oven heating, and the hatched region indicates the region sealed with the first varnish after microwave oven heating. As shown in Fig. 8, the case where the seal of the first varnish region 21 is peeled off and seal recession occurs near the intersection 6 was defined as Evaluation B. In Fig. 8, the dashed-dotted line region indicates the first varnish region 21 before microwave oven heating, and the region surrounded by the two-dot chain line schematically shows the region where seal recession occurs.

[0069] Each of the packaging bags of Samples 1 to 19 has two intersections 6. Therefore, when the evaluations of both intersections 6 are Evaluation A+, the comprehensive evaluation of the sealing state of the intersection 6 was defined as A+. When the evaluation of the two intersections 6 is A or A+, if one or both are evaluated as A, the overall evaluation of the sealing state of the intersection 6 was set as evaluation A. When evaluation B is included in the evaluation of one of the evaluations of the two intersections 6, the overall evaluation of the sealing state of the intersection 6 was set as evaluation B.

[0070] The results of the overall evaluation of the sealing state of the intersection 6 in the packaging bags that are Samples 1 to 19 were as shown in the chart in Fig. 9.

[0071] From the results shown in Fig. 9, in Samples 1, 3 to 10, 15 to 19 where the load index X was 3000 or more, the evaluation was A or A+. That is, even when a load was generated at the intersection 6 by microwave heating, no seal recession occurred at the intersection 6 portion. Therefore, in microwave heating, it is possible to prevent the occurrence of an unintentional opening at the intersection 6 portion.

[0072] The evaluation of Samples 1, 6 to 10, 17 to 19 where the load index X was 4000 or more was A+. Therefore, it was found that by configuring the packaging bag 1 so that the load index X becomes 4000 or more, the load on the intersection 6 can be further reduced.

[0073] As described above, the larger the load index X, the lower the load on the intersection 6. By providing the first varnish region 21, a larger load index X can be realized, and as a result, it can be understood that the load on the intersection 6 can be easily reduced.

[0074] As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above-exemplified embodiments, and includes the scope indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. Also, the exemplified embodiments and variations may be appropriately combined as long as they do not deviate from the gist of the present invention.

[0075] For example, the gusset portion may be formed on both sides in the y direction, that is, on the side 1a side and the side 1b side. In this case, since there are four intersections 6 in the packaging bag, the packaging bag is configured such that Condition I or Condition II is satisfied at each intersection 6.

[0076] In a packaging bag having no first glue region, a second glue region may be formed. In this case, for example, in FIG. 4, the second glue region 22 may be formed at the position of the first glue region 21.

Explanation of Signs

[0077] 1... Packaging bag, 4a... Side, 2... Back sticker seal portion, 3... Gusset portion, 3a... Fold line, 4, 4A, 4B... Seal portion, 5... Venting process portion, 6... Intersection.

Claims

1. A pillow-shaped packaging bag for microwave heating, having a back-sealing portion, sealing portions formed at both ends in a first direction which is the extending direction of the back-sealing portion, a gusset portion formed on one side in a second direction orthogonal to the first direction, and a steam venting portion formed in a region other than the gusset portion for venting internal steam during microwave heating, wherein a first region including the intersection of the folding line in the gusset portion and the inner side of the sealing portion among the inner surfaces facing each other at both ends in the first direction of the gusset portion is sealed with a first varnish having sealing properties in a 70°C environment, when the load index X1 at the intersection is defined by formula (1A), X1 is 3000 or more, a packaging bag. X1 = (R - G + t1) × W... (1A) R in formula (1A) is defined by formula (2). R = 2 × (W - 2 × s) ÷ π... (2) In formulas (1A) and (2), W is the length of the packaging bag in the first direction, G is the length of the gusset portion in the second direction, s is the length of the sealing portion in the first direction, and t1 is the length of the first region in the second direction.

2. A second region adjacent to the first region in the second direction is sealed with a second varnish having sealing properties at room temperature or below, the packaging bag according to Claim 1.

3. The gusset portion has a pair of gusset pieces extending along the first direction, both ends in the first direction of each of the pair of gusset pieces are sealed with the sealing portion, and the sealing portions in each of the pair of gusset pieces are sealed with the first varnish, the packaging bag according to Claim 1 or 2.

4. A pillow-shaped packaging bag for microwave heating, having a back-sealing portion, sealing portions formed at both ends in a first direction which is the extending direction of the back-sealing portion, a gusset portion formed on one side in a second direction orthogonal to the first direction, and a steam venting portion formed in a region other than the gusset portion for venting internal steam during microwave heating, wherein when the load index X2 at the intersection of the folding line in the gusset portion and the inner side of the sealing portion is defined by formula (1B), X2 is 3000 or more, a packaging bag. X2 = (R - G + t1) × W... (1B) R in formula (1B) is defined in formula (2). R = 2 × (W - 2 × s) ÷ π... (2) In formulas (1B) and (2), W is the length of the packaging bag in the first direction, G is the length of the gusset portion in the second direction, and s is the length of the seal portion in the first direction.

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