Patent Application
20240308749
The present invention relates to a packaging bag suitable for heating contents in a microwave oven.
Patent Literature 1 discloses a packaging bag configured by heat-sealing a flexible film at a seal portion. This packaging bag is provided with a vapor release seal portion to release vapor generated when the contents are heated in a microwave oven.
In Patent Literature 1, the vapor release seal portion has a curved shape that is curved toward the inner direction of the packaging bag. As the internal pressure of the packaging bag increases, the distal end of the curved shape peels off to form an opening, and vapor is discharged through this opening. To quickly discharge the vapor in the packaging bag, it is ideal that the peeling that has started at the distal end of the curved shape quickly progresses to a portion other than the distal end to expand the opening, but there are cases in which the peeling does not progress quickly. If the peeling does not progress quickly, the internal pressure of the packaging bag may become too high, for example, in the case of rapid heating, and an opening may be formed at a portion other than the vapor release seal portion, and vapor may be discharged from the opening.
The present invention has been made in view of such circumstances and provides a packaging bag that can suppress the formation of an opening at a portion other than the vapor release seal portion.
According to the present invention, provided is a packaging bag made of a film heat-sealed at a seal portion, wherein the seal portion comprises a vapor release seal portion configured to form a vapor flow path as an internal pressure increases, the vapor release seal portion has a curved shape curved toward an inner direction of the packaging bag, the vapor release seal portion includes a first region including a distal end of the curved shape and a second region adjacent to the first region, and sealing strength in the first region is higher than sealing strength in the second region.
In the packaging bag of the present invention, the sealing strength of the first region that constitutes the vapor release seal portion and includes the distal end of the curved shape is higher than the sealing strength of the second region adjacent to the first region. Thus, when the peeling starts in the first region, the peeling progresses quickly in the second region. Therefore, the opening formed in the vapor release seal portion expands quickly, and thus the formation of an opening at a portion other than the vapor release seal portion is suppressed.
Hereinafter, various embodiments of the present invention will be exemplified. The embodiments shown below can be combined with each other.
Preferably, the packaging bag comprises a front surface portion having a lower front surface portion and an upper front surface portion, at a joint portion where an inner surface of the lower front surface portion and an inner surface of the upper front surface portion are partially overlapped, the lower front surface portion and the upper front surface portion are heat-sealed at a pair of side seal portions, a pair of end seal portions, and the vapor release seal portion, the side seal portions are provided along side edges of the joint portion and are connected to the vapor release seal portion via the end seal portions, and sealing strength at the end seal portions is higher than the sealing strength in the first region.
Preferably, the vapor release seal portion comprises an inner region and an outer region configured by dividing the vapor release seal portion at a boundary line located between an inner edge and an outer edge of the vapor release seal portion, and the inner region and the outer region differ from each other in sealing strength.
Preferably, provided is a seal bar used for manufacturing the above-described packaging bag, comprising: a vapor release seal forming portion for forming the vapor release seal portion, wherein the vapor release seal forming portion comprises a first region forming portion for forming the first region and a second region forming portion for forming the second region, and a protrusion amount of the first region forming portion is larger than a protrusion amount of the second region forming portion.
Preferably, the seal bar further comprises an end seal forming portion for forming the end seal portion, wherein a protrusion amount of the end seal forming portion is larger than the protrusion amount of the first region forming portion.
Preferably, the seal bar further comprises first and second sealing units, wherein the vapor release seal forming portion is a first vapor release seal forming portion, the first sealing unit comprises the first vapor release seal forming portion, the second sealing unit comprises a second vapor release seal forming portion for forming the vapor release seal portion, and the first and second vapor release seal forming portions differ from each other in line width.
Preferably, provided is a manufacturing method, comprising: a step of forming the vapor release seal portion by a sealing step including first and second sealing steps, wherein, in the first sealing step, the film is heat-sealed using a first sealing unit having a first vapor release seal forming portion, in the second sealing step, the film is heat-sealed using a second sealing unit having a second vapor release seal forming portion, and the first and second vapor release seal forming portions differ from each other in line width.
Hereinafter, embodiments of the present invention will be described. Various characteristics in the embodiments described below can be combined with each other. Further, the invention is independently established for each characteristic.
As shown in
As shown in
The base material layer 9a is formed of a material having excellent strength and high impact resistance. As the base material layer 9a, for example, polyamide, polyolefin, polyethylene, polyester, and the like are used. More specifically, oriented polyethylene terephthalate film, silica-deposited oriented polyethylene terephthalate film, alumina-deposited oriented polyethylene terephthalate film, oriented nylon film, oriented polypropylene film, polypropylene/ethylene-vinyl alcohol copolymer co-extruded co-oriented film, or the like can be used. As a film forming the base material layer 9a, a film having straight line cuttability in the MD direction (the direction in which the film flows during manufacturing) is preferably used. The base material layer 9a, which is the outermost layer, may contain antibacterial or antiviral agent, such as silver ions. In particular, by kneading a bleed-out antibacterial or antiviral agent into the base material layer 9a, the antibacterial or antiviral treatment progresses on the surface of the base material layer 9a when it is heated to a high temperature in a microwave oven, which is hygienic and preferable when removing from the microwave oven.
The adhesive layer is a layer for allowing the base material layer 9a and the sealant layer 9b to adhere to each other so as to be laminated. The adhesion method may be extrusion lamination using, for example, polyethylene as the adhesive layer, or may be dry lamination using polyvinyl acetate adhesive, polyacrylate adhesive, cyanoacrylate adhesive, ethylene copolymer adhesive, cellulose adhesive, polyester adhesive, polyamide adhesive, amino resin adhesive, epoxy adhesive, polyurethane adhesive, and the like as adhesive material.
The sealant layer 9b can be formed of resin with excellent heat sealability. The sealant layer 9b can be formed with polyolefin-based resins, such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer, and ethylene-propylene block copolymer. More specifically, non-oriented polypropylene and linear low-density polyethylene can be used.
As shown in
The vapor release seal portion 8 is configured to form a vapor flow path as the internal pressure of the packaging bag 1 increases. The vapor release seal portion 8 has a curved shape that is curved toward the inner direction of the packaging bag 1. An inner edge 8a of the vapor release seal portion 8 is preferably substantially V-shaped, and an outer edge 8b of the vapor release seal portion 8 is also preferably substantially V-shaped. The inner edge 8a and the outer edge 8b preferably have a portion parallel to each other, and the entire inner edge 8a and outer edge 8b are preferably parallel to each other. The distance between the inner edge 8a and the outer edge 8b (that is, the line width of the vapor release seal portion 8) is, for example, 1 to 5 mm, and preferably 2 to 4 mm. This distance is, specifically, for example, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0 mm and may be in a range between any two of the numerical values exemplified herein.
The vapor release seal portion 8 includes a first region 8d including a distal end 8c of the curved shape and a second region 8e adjacent to the first region. The second region 8e is a region other than the first region 8d in the vapor release seal portion 8. The inner edge 8a and the outer edge 8b may be parallel to each other in the first region 8d and may be parallel to each other in the second region 8e. It is preferable to provide the unseal portion 10 between the outer edge 8b and the upper edge 5t. It is preferable to provide a cut 12 between the outer edge 8b and the upper edge 5t.
The sealing strength in the first region 8d is higher than the sealing strength in the second region 8e. Although it is assumed that the peeling in the vapor release seal portion 8 starts from the distal end 8c, the peeling at the distal end 8c may start at an unintended timing, such as when the packaging bag 1 is subjected to an impact, if the peeling starts too easily at the distal end 8c. On the other hand, if the sealing strength of the entire vapor release seal portion 8 is increased to prevent opening at an unintended timing, there arises a problem that peeling does not proceed quickly even if peeling starts at the distal end 8c. Therefore, in the present embodiment, the sealing strength in the first region 8d is higher than that in the second region 8e. In such a configuration, since the sealing strength in the first region 8d is relatively high, it is possible to suppress the peeling at the distal end 8c from starting at unintended timing. On the other hand, since the sealing strength in the second region 8e is relatively low, when peeling starts in the first region 8d, the peeling proceeds quickly in the second region 8e. Consequently, an opening formed in the vapor release seal portion 8 expands quickly, and thus the formation of an opening in a portion other than the vapor release seal portion is suppressed. In this regard, the sealing strength means sealing strength per unit area unless otherwise specified.
W1/W is preferably 0.05 to 0.5 and more preferably 0.1 to 0.3, where W represents the overall width (the length in the left-right direction) of the vapor release seal portion 8, and W1 represents the width of the first region 8d. W1/W is specifically, for example, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, or 0.50 and may be in a range between any two of the numerical values exemplified herein.
The vapor release seal portion 8 preferably includes an inner region 8g and an outer region 8h configured by dividing the vapor release seal portion 8 at a boundary line 8f located between the inner edge 8a and the outer edge 8b of the vapor release seal portion 8. Preferably, the inner region 8g and the outer region 8h differ from each other in sealing strength. Preferably, the sealing strength in the inner region 8g is higher than the sealing strength in the outer region 8h. By increasing the sealing strength of a part of the vapor release seal portion 8 along the line width direction, it is possible to prevent the peeling of the vapor release seal portion 8 at an unintended timing. The boundary line 8f is preferably parallel to at least one of the inner edge 8a and the outer edge 8b. The ratio of the line width of the inner region 8g to the overall line width of the vapor release seal portion 8 is, for example, 0.1 to 0.9 and preferably 0.2 to 0.8. This ratio is, specifically, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9 and may be in a range between any two of the numerical values exemplified herein. In the present embodiment, the ratio of the line width of the inner region 8g is 0.5.
After the packaging bag 1 is filled with the contents, a bottom seal portion is formed at a lower edge of the packaging bag 1. Consequently, the inside of the packaging bag 1 is sealed.
When the packaging bag 1 filled with the contents is heated in a microwave oven, the internal pressure of the packaging bag 1 increases due to vapor generated from the moisture contained in the contents. Consequently, when the peeling starts in the first region 8d including the curved distal end 8c of the vapor release seal portion 8, the peeling proceeds quickly in the second region 8e. Consequently, the vapor flow path formed in the vapor release seal portion 8 expands quickly, and the vapor is quickly released to the outside. The vapor is released to the outside from the upper edge 5t of the joint portion 5 and from the cut 12.
The packaging bag 1 can be formed by forming the seal portion 4 on the film 9. In one example, the seal portion 4 can be formed by heat-sealing the film 9 folded into the shape shown in
The seal bar 20 includes first and second sealing units 21, 22. The first sealing unit 21 includes a vapor release seal forming portion 21a for forming the vapor release seal portion 8 and an end seal forming portion 21b for forming the end seal portion 7. The vapor release seal forming portion 21a includes a first region forming portion 21a1 for forming the first region 8d and a second region forming portion 21a2 for forming the second region 8e. The protrusion amount of the first region forming portion 21a1 is larger than the protrusion amount of the second region forming portion 21a2. The protrusion amount of the end seal forming portion 21b is larger than the protrusion amount of the first region forming portion 21a1. That is, the protrusion amount is set such that the second region forming portion 21a2<the first region forming portion 21a1<the end seal forming portion 21b. During heat-sealing, the portion with a larger protrusion amount is pressed more strongly against the film 9 to increase the sealing strength of the film 9. Therefore, when the end seal portion 7 and the vapor release seal portion 8 are formed using the seal bar 20 of the above-described configuration, the sealing strength can be such that the second region 8e<the first region 8d<the end seal portion 7.
The difference in the protrusion amount between the second region forming portion 21a2 and the first region forming portion 21a1 is, for example, 1 to 100 μm, preferably 5 to 30 μm, specifically, for example, 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 μm and may be in a range between any two of the numerical values exemplified herein. The same applies to the difference in the protrusion amount between the first region forming portion 21a1 and the end seal forming portion 21b.
The second sealing unit 22 has the same basic configuration as the first sealing unit 21, and reference signs of various portions of the second sealing unit 22 correspond to the reference signs of the portions of the first sealing unit 21 changed from “21” to “22”. The first and second sealing units 21, 22 are connected to each other at the end seal forming portions 21b, 22b.
The vapor release seal forming portions 21a, 22a of the first and second sealing units 21, 22 differ from each other in the distance between the inner edge and the outer edge of the vapor release seal forming portions 21a, 22a (that is, the line width of the vapor release seal forming portion). The value of (line width of the vapor release seal forming portion having a larger line width)/(line width of the vapor release seal forming portion having a smaller line width) is, for example, 1.1 to 5 and preferably 1.5 to 3. This value is specifically, for example, 1.1, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0 and may be in a range between any two of the numerical values exemplified herein. In the present embodiment, the above-described value is 2. In the present embodiment, in
The vapor release seal portion 8 can be formed by a sealing step including first and second sealing steps. In the first sealing step, the film 9 is heat-sealed using the first sealing unit 21 having the first vapor release seal forming portion 21a, and in the second sealing step, the film 9 is heat-sealed using the second sealing unit 22 having the second vapor release seal forming portion 22a.
In one example, the film 9 is moved after performing the first sealing step to move the end seal portion 7 and the vapor release seal portion 8 formed in the first sealing step to a position facing the second sealing unit 22, and then the second sealing step can be formed. The first and second sealing units 21, 22 are adjacent to each other in the seal bar 20. Therefore, when the second sealing step is performed on a first packaging bag 1, the first sealing step can be performed on a second packaging bag 1 on an upstream side. Therefore, when a large number of packaging bags 1 are sequentially manufactured, the manufacturing time per bag can be reduced.
Since the vapor release seal forming portions 21a, 22a differ from each other in line width, they also differ from each other in sealing width on the film 9. By forming the vapor release seal portion 8 by such a step, the sealing strength of the inner region 8g and the outer region 8h can be different from each other. In one example, only the inner region 8g is heat-sealed in the first sealing step, and both the inner region 8g and the outer region 8h are heat-sealed in the second sealing step. Consequently, the sealing strength of the inner region 8g can be higher than the sealing strength of the outer region 8h.
In this regard, although the case where one seal bar 20 includes the first and second sealing units 21, 22 is taken as an example, the first and second sealing units 21, 22 may be provided on separate seal bars.
A second embodiment of the present invention will be described with reference to
In the packaging bag 1 of the first embodiment, depending on the resin composition of the sealant layer, the sealing strength in the first region 8d may become too high, resulting in slow vapor release, which may cause loud noise when the vapor release seal portion 8 is opened. For example, when the sealant layer is made of LLDPE, the sealing strength in the first region 8d is likely to be too high compared to when the sealant layer is made of non-oriented polypropylene.
To reduce the sealing strength in the first region 8d, the pressure at which the seal bar 20 is pressed can be reduced. However, since the fine adjustment of the pressure at which the seal bar 20 is pressed is not easy, the variation in the sealing strength from product to product tends to increase as a result of reducing the pressure at which the seal bar 20 is pressed.
In the present embodiment, to solve such a problem, a protruding portion 8d2 is provided in the first region 8d to improve the peelability in the first region 8d. Consequently, regardless of the resin composition of the sealant layer, it is possible to suppress the generation of a loud noise when the vapor release seal portion 8 is opened.
Specifically, in the present embodiment, the first region 8d includes a base portion 8d1 and the protruding portion 8d2, as shown in
The distal end of the protruding portion 8d2 is provided with a weak seal region 8d3. The weak seal region 8d3 is a portion where the sealing strength is weaker than that of the protruding portion 8d2. By providing the weak seal region 8d3, the peeling at the protruding portion 8d2 is more easily started.
Further, in the present embodiment, the ratio of the line width of the inner region 8g to the overall line width of the vapor release seal portion 8 is about 0.8. Consequently, the peeling in the second region 8e at an unintended timing is suppressed more effectively.
In the present embodiment, using the seal bar 20 shown in
In the first sealing unit 21 of the seal bar 20 of the present embodiment, the first region forming portion 21a1 for forming the first region 8d includes a base portion 21a3 and a protruding portion 21a4. The distal end of the protruding portion 21a4 is provided with a chamfered portion 21a5. The chamfered portion 21a5 is configured by chamfering the distal end of the protruding portion 21a4. This chamfer may be an R chamfer or a C chamfer. By providing the chamfered portion 21a5, the protruding portion 21a4 is prevented from damaging the film. The base portion 21a3, the protruding portion 21a4, and the chamfered portion 21a5 form the base portion 8d1 of the first region 8d, the protruding portion 8d2, and the weak seal region 8d3, respectively. The second sealing unit 22 is similarly configured, and reference signs of various portions of the second sealing unit 22 correspond to the reference signs of the portions of the first sealing unit 21 changed from “21” to “22”.
Further, in the present embodiment, the vapor release seal forming portions 21a, 22a differ from each other in the distance between the inner edge and the outer edge of the vapor release seal forming portions 21a, 22a (that is, the line width of the vapor release seal forming portion). The value of (line width of the vapor release seal forming portion having the larger line width)/(line width of the vapor release seal forming portion having the smaller line width) is 1.25.
Further, in the present embodiment, the end seal forming portion 21b and the first region forming portion 21a1 have the same amount of protrusion, and they have a larger amount of protrusion than the second region forming portion 21a2. Therefore, when the seal bar 20 of the present embodiment is used to form the end seal portion 7 and the vapor release seal portion 8, the sealing strength becomes such that the second region 8e<the first region 8d=the end seal portion 7.
The packaging bag 1 with the vapor release seal portion 8 having the same shape as in the first embodiment was prepared using the film 9 in which a polyamide layer with a thickness of 15 μm and a non-oriented polypropylene with a thickness of 60 μm were laminated. The packaging bag 1 was filled with water.
When the packaging bag 1 was heated in a microwave oven to test whether the vapor release seal portion 8 functions properly (vapor discharge test), it was confirmed that vapor was discharged from the vapor release seal portion 8 without loud noise.
The packaging bag 1 was manufactured in the same manner as in Example 1 except that the non-oriented polypropylene layer was changed to an LLDPE layer. When the vapor discharge test was performed, there was a case where a loud noise was generated when the vapor release seal portion 8 is opened.
The packaging bag 1 was manufactured in the same manner as in Example 2 except that the shape of the vapor release seal portion 8 was changed to that of the second embodiment. When the vapor discharge test was performed, it was confirmed that vapor was discharged from the vapor release seal portion 8 without loud noise.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-012408 | Jan 2021 | JP | national |
| 2021-091746 | May 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/002545 | 1/25/2022 | WO |
