JP2024052960A - Steam-through pouch - Google Patents

Abstract

[Problem] To provide a steam-passing pouch whose opening part can be torn easily, linearly and neatly by hand even after heating, and from which the contents can be easily removed. [Solution] The steam-passing pouch is made up of two opposing body member sheets and a bottom member sheet folded over the bottom, and has a storage space for storing contents, formed by sealing the peripheries of the left and right side faces and the bottom face to form respective sealed parts, and further filled with contents from the top of the body member sheet and then hermetically sealing the top face, and is provided with a steam-passing part in at least one of the sealed parts on the left and right sides for releasing steam from the storage space when heated, and an opening part on the bottom face below the steam-passing part and substantially parallel to the bottom face, wherein the body member sheets include an outermost layer, an intermediate layer, and a sealant layer made of a non-oriented film, in that order, and the opening part has an easy-opening line formed in the intermediate layer. [Selected Figure] Figure 1

Description

The present invention relates to a steam-permeable pouch whose opening can be easily torn by hand or the like and which can also be used as a container for eating after opening.

For example, microwave pouches that contain contents to be heated, such as retort foods and frozen foods, are widely used. When such pouches are heated in a microwave oven, the moisture in the contents evaporates as the pouch is heated, increasing the pressure inside the pouch. If the pressure inside the pouch increases, there is a risk that the pouch will break, causing the contents to splash out and soil the inside of the microwave oven. For this reason, steam-permeable pouches equipped with a steam release mechanism are known that allow the pressure inside the pouch that increases as the pouch is heated to escape to the outside.

The steam-passing pouch includes a sheet that is sealed to form a storage space capable of storing contents, a steam-passing portion in which a portion of the sheet is sealed to open as the pressure in the storage space increases, and an opening that allows the contents to be filled into the storage space. When contents are stored in the storage space of the steam-passing pouch, the opening is sealed to close the storage space. When a steam-passing pouch containing contents is heated by a heating means such as a microwave oven, water vapor is generated from the contents, the pressure in the storage space increases, and stress is generated in each part of the sheet. When the pressure in the storage space increases to a certain level, the seal that constitutes the steam-passing portion peels off, and a passage that connects the storage space to the outside space is formed in the steam-passing portion. As a result, moisture in the storage space passes through the passage formed in the steam-passing portion and is discharged to the outside of the pouch, suppressing the increase in pressure in the storage space.

Patent Document 1 discloses a microwave pouch, which is an example of a conventional steam-permeable pouch. As shown in Patent Document 1, this microwave pouch includes a laminated sheet. The laminated sheet includes a base layer, a printed layer, other layers, and a sealant layer. When heating of the microwave pouch containing the contents by the heating means is completed, the laminated sheet is torn from the opening portion, and the contents are removed from the storage space.

JP 2018-127257 A

However, with the microwave pouch described in Patent Document 1, when attempting to tear the laminated sheet from the opening by hand, etc., the innermost sealant layer stretches during the tearing process, making it impossible to tear in a straight line, or causing fuzzing or wavy deformation at the tearing point, resulting in an insufficient opening and making it difficult to easily remove the contents from the opening.

The present invention was made in consideration of the above problems, and aims to provide a steam-permeable pouch whose opening can be torn easily, linearly and neatly by hand even after the pouch has been heated, allowing the contents to be easily removed.

In order to solve the above problems, the present invention provides
According to claim 1 of the present invention,
The bag comprises two opposing body member sheets and a bottom member sheet that is folded onto the bottom surface,
the left side surface, the right side surface and the bottom surface are sealed at their peripheries to form respective sealed portions, and the contents are filled from the top of the body member sheet and then the top is hermetically sealed to provide a storage space for storing the contents;
A steam-passing pouch having a steam passage portion for releasing steam in the storage space when heated in at least one of the left and right side seal portions, and an opening portion on a bottom surface side below the steam passage portion and substantially parallel to the bottom surface,
The sheet includes an outermost layer, an intermediate layer, and a sealant layer made of a non-stretched film, in this order;
The steam-passing pouch is characterized in that an easy-open line is formed in the intermediate layer in the opening portion.

When the steam-passing pouch is heated in a sealed state after the contents are placed in the storage space, a passage that connects the storage space to the outside space is formed in the steam-passing section as the pressure in the storage space rises. Therefore, the water vapor in the storage space passes through the passage formed in the steam-passing section and is discharged to the outside of the steam-passing pouch, suppressing the rise in pressure in the storage space. In addition, there is an opening section on the bottom side of the steam-passing section that is approximately parallel to the bottom, and the sheet can be easily torn in the width direction along the easy-to-open line formed in the middle layer of the body member sheet. In addition, since it is formed only in the middle layer, the body member sheet is not penetrated and steam does not leak out, so the expanded state of the pouch is maintained and steaming can be performed suitably. The contents can then be easily removed from the part where the body member sheet is torn.

According to claim 2 of the present invention, the easy-open line is formed continuously or intermittently by laser processing. By adjusting the output and scanning speed of the laser head, the shape and depth of the easy-open line can be adjusted relatively easily, making it possible to form the easy-open line only in the middle layer.

According to claim 3 of the present invention, at least one of the seal portions on the left and right sides has a notch on the bottom side below the steam passage portion, and the notch is formed so that its tip is located on an imaginary line extending from the easy-open line. The easy-open line is a collection of one or more small holes, but multiple holes are preferable because it is easier to align the tip of the notch with an extension of the easy-open line. There may be gripping portions above and below the notch, and the sheet can be easily torn in the width direction along the easy-open line by using the notch as the starting point for tearing.

According to claim 4 of the present invention, the sealant layer of the body member sheet is made of a material that is heat resistant and easy to tear in the width direction, so the sheet can be torn easily. Therefore, the contents can be easily removed from the torn part of the sheet.

According to claim 5 of the present invention, the material constituting the sealant layer may contain unstretched polypropylene.

According to claim 6 of the present invention, the bottom material sheet is folded between the two opposing body material sheets, and then formed and sealed in a form having a gusset portion, and the bottom is molded into a square bottom, so that when the internal pressure increases due to heating, the bottom of the pouch is easily opened, the self-supporting state is stabilized, and when the pouch is opened to form an opening at the top, the width of the opening is expanded, making it easier to remove the contents and enabling them to be eaten directly from the pouch.

With the steam-permeable pouch of the present invention, the opening can be torn easily, linearly and neatly by hand even after the pouch has been heated, allowing the contents to be easily removed.

FIG. 1 is a perspective view of a steam-passing pouch showing an example of an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a layer structure of a member sheet used in the present invention. FIG. 4 is an enlarged view of the steam passage portion and its surroundings in an open state. FIG. 2 is a front view of the steam-permeable pouch in an opened state.

An example of an embodiment of the present invention will be described below. FIG. 1 shows an example of a steam-permeable pouch 10 capable of storing contents 15 suitable for heating and discharging steam generated from the contents 15. The contents 15 are heated objects that generate water vapor when heated. An example of the contents 15 is food. An example of the food is a food having fluidity such as stew and soup. The steam-permeable pouch 10 is configured to be able to store the contents 15 for a long period of time while maintaining the quality of the contents 15. Examples of shapes that the steam-permeable pouch 10 can take include freestanding types such as a standing type and a gusset type. The shape of the steam-permeable pouch 10 exemplified in FIG. 1 is a square-bottom type whose bottom is molded into a square bottom. Hereinafter, the left-right direction of the steam-permeable pouch 10 in a front view of the steam-permeable pouch 10 is referred to as the standard width direction, and the direction perpendicular to the standard width direction is referred to as the standard height direction.

The steam-permeable pouch 10 includes a body member sheet 20, a bottom member sheet 23, an upper seal portion 31, a bottom seal portion 32, a right side seal portion 33, a left side seal portion 34, an opening portion 50, and a steam-permeable portion 60. The body member sheet 20 is made up of a front sheet 21 and a back sheet 22. The front sheet 21 and the back sheet 22 face each other so that a storage space 11 for storing contents 15 is formed between the sheets 21, 22. The bottom member sheet 23 is folded around the periphery and sealed to close the gap between the bottom of the front sheet 21 and the bottom of the back sheet 22.

The body member sheet 20 (21, 22) and the bottom member sheet 23 have a layered structure in which multiple layers are stacked. Figure 2 is a cross-sectional view showing the layer structure of these member sheets 20-23. The member sheets 20-23 include an outermost layer 20A, an intermediate layer 20B, a sealant layer 20C, a first adhesive layer 20D, and a second adhesive layer 20E. One example of a manufacturing method for each of the sheets 21-23 is dry lamination. The first adhesive layer of each of the sheets 21-23 is provided between the outermost layer and the intermediate layer, and the second adhesive layer is provided between the intermediate layer and the sealant layer.

The outermost layer 20A is mainly excellent in gas barrier properties, printability, and heat resistance. The outermost layer 20A is, for example, a transparent vapor deposition layer. An example of a material constituting the outermost layer 20A is polyethylene terephthalate (hereinafter referred to as "vapor deposition PET") on which an inorganic thin film is vapor-deposited. The intermediate layer 20B is mainly excellent in heat resistance and moisture resistance. An example of a material constituting the intermediate layer 20B is polyethylene terephthalate having an easy tearing property in the width direction of the body member sheet 20. Hereinafter, the orientation direction of the material constituting each sheet 21, 22 is referred to as the MD (Machine Direction) direction, and the direction perpendicular to the MD direction is referred to as the TD (Transverse Direction) direction. The MD direction of each sheet 21, 22 is the direction along the standard width direction. The TD direction of each sheet 21, 22 is the direction along the standard height direction. An example of a material constituting the first adhesive layer 20D is a polyester-based adhesive. An example of a material that can be used to form the second adhesive layer 20E is a polyester adhesive.

The sealant layer 20C has excellent heat resistance, heat sealability, and impact resistance. One example of a material that constitutes the sealant layer 20C is non-oriented polypropylene (hereinafter referred to as "CPP"), which has excellent tear resistance in the MD direction.

Excellent tear strength in the MD direction means, for example, that the tear strength according to the trouser tear method stipulated in JIS standard K7128-1 is 1.2 N or less. In the trouser tear method, a 75 mm cut was made in the center of a rectangular test piece 50 mm long in the TD direction and 150 mm long in the MD direction, and the tear strength in the MD direction was measured at a speed of 200 mm/min in a thermostatic chamber at 23°C.

The sealed portions 31-34 shown in FIG. 1 join the sheets 21-23 together so that they do not separate. One example of a method for forming the sealed portions 31-34 is heat sealing. The outer shape of the steam-permeable pouch 10 as viewed from the front can be selected as desired. In the example shown in FIG. 1, the outer shape of the steam-permeable pouch is rectangular.

<Method of manufacturing steam-passing pouch>
Next, a method for manufacturing the steam-permeable pouch 10 will be described. First, the front sheet 21 and the back sheet 22 made of the body member sheet 20 are prepared. Next, the bottom member sheet 23 (which may be the same as the front sheet 21 and the back sheet 22 or may be different) is inserted between the lower part of the front sheet 21 and the back sheet 22 up to the folded part to form a form having a gusset part. Next, the inner surfaces of each sheet are heat-sealed to each other to form seal parts such as the bottom seal part 32, the right side seal part 33, and the left side seal part 34, thereby obtaining the steam-permeable pouch 10 having a square bottom shape as shown in FIG. 1. Next, the upper part of the body member sheet 20 is heat-sealed at the upper seal part 31, but this part is used as a filling port for the contents 15, so that it is an unsealed opening before filling the contents 15, and is heat-sealed after filling the contents 15. In the above example, an example was described in which the steam-permeable pouch 10 is constructed using three sheets of packaging material, namely, the front sheet 21, the back sheet 22, and the body member sheet 20, but the number of sheets of packaging material that constitute the steam-permeable pouch 10 is not particularly limited.

<Opening section>
The opening section 50 has a notch 51 in at least one of the left and right side seal sections. The notch 51 may have gripping sections 53 and 54 above and below the notch 51. It is also preferable to provide an easy-to-open line 52 on the middle layer of the body member sheet 20, which guides the tearing of the body member sheet 20, from the right end of the left side seal section to the left end of the right side seal section at the same height as the notch 51 in the standard height direction. The opening section 50 (notch 51, easy-to-open line 52) can be provided at any position in the standard height direction. In one example shown in FIG. 1, the opening section 50 is provided between the steam passage section 60 and the bottom member sheet 23 in the standard height direction. In a preferred example, the opening section 50 is provided at a position closer to the steam passage section 60 than the bottom member sheet 23 in the standard height direction.

The easy-open line 52 is a collection of small holes formed by laser processing on the middle layer of the body material sheet 20, and is formed along the MD direction of the body material sheet 20. The notch 51 is formed in at least one of the right side seal portion 33 and the left side seal portion 34 so that the tip of the notch 51 is located on an imaginary line extending from the end of the easy-open line 52. Figure 1 shows an example in which the notch 51 is formed in the left side seal portion 34.

Notches 51 may be V-notches consisting of V-shaped cutouts as shown in FIG. 1, pentagonal (hexagonal) notches consisting of pentagonal cutouts, U-notches consisting of U-shaped cutouts, I-notches consisting of I-shaped cutouts, Notchnon (registered trademark) consisting of scratch processing, etc., but notches consisting of cutouts with width are preferred because it is easier to align the end of the easy-open line with the notch.

The tear strength of the tear section 50 where the easy-open line 52 is formed is lower than that of other parts of the body member sheet 20 where the easy-open line 52 is not formed. Therefore, when a force is applied to the tear section 50 in a direction along the easy-open line 52, the body member sheet 20 is easily torn along the easy-open line 52. The easy-open line 52 includes a plurality of cuts 52A formed discontinuously in the standard width direction. The easy-open line 52 is formed by, for example, a laser processing machine.

The easy-to-open line 52 is formed by a laser processing machine that irradiates the outermost layer 20A of the body member sheet 20 with a laser. With a method using a laser processing machine, it is possible to cut only a specific layer by taking advantage of the fact that the way energy is absorbed differs depending on the material. As an example of this, a carbon dioxide laser with a wavelength of 10.6 μm is used as the laser, and by adjusting the output and scanning speed of the laser head depending on the material, the shape and depth of the easy-to-open line 52 can be adjusted relatively easily.

The shape of the cut 52A may be any of straight lines, curved lines, perforated lines, broken lines, etc., and the number of cuts may be one or more in the standard height direction. In the present invention, the cut 52A portion should act as an easy-to-open line.

In a preferred example, the cut 52A does not penetrate all three layers of the outermost layer 20A, the middle layer 20B, and the sealant layer 20C that make up the body member sheet 20, and is formed in one of the three layers. Because the cut 52A does not penetrate the three layers of the body member sheet 20, the contents 15 contained in the storage space 11 cannot pass through the easy-open line 52 to the outside. In this embodiment, the cut 52A is provided so as to penetrate only the middle layer 20B of the body member sheet 20.

<Steam passage section>
The steam-passing pouch 10 is heated by a heating means to heat the contents 15. An example of the heating means is a microwave oven. When the steam-passing pouch 10 is heated, water vapor is generated from the contents 15. As the water vapor is generated, the pressure in the storage space 11 increases. The steam-passing section 60 is configured to open as the pressure in the storage space 11 increases, so that the water vapor in the storage space 11 can be discharged to the outside of the steam-passing pouch 10. In a preferred example, the steam-passing section 60 is configured to open when the pressure in the storage space 11 increases to a pressure within a predetermined pressure range.

The vapor passage portion 60 can take various forms. In one example, the vapor passage portion 60 is provided in at least one of the right side seal portion 33 and the left side seal portion 34. In another example, the vapor passage portion 60 is provided inside the seal portion, independent of the right side seal portion 33 and the left side seal portion 34. FIG. 1 shows an example in which the vapor passage portion 60 is provided only in the right side seal portion 33.

As shown in FIG. 1, the shape of the vapor passage section 60 is recessed from the outside to the inside in the standard width direction. The tip section 61, which is the innermost part of the vapor passage section 60 in the standard width direction, is provided at a location where strong stress concentration occurs when the pressure in the storage space 11 of the body member sheet 20 increases. It opens when the pressure in the storage space 11 increases to within a predetermined pressure range.

<How to release steam>
Specifically, as the pressure in the storage space 11 increases, the front sheet 21 and the back sheet 22 joined at the tip 61 of the steam-passing portion 60 are peeled off, and as shown in FIG. 3, a steam release passage 62 that communicates the storage space 11 with the outside of the steam-passing pouch 10 is formed in the steam-passing portion 60. The range in which the steam-passing portion 60 peels off varies depending on the pressure in the storage space 11. When the pressure in the storage space 11 is high, peeling may progress to the base of the steam-passing portion 60. The passage area of the steam release passage 62 becomes wider as peeling of the steam-passing portion 60 progresses. When the steam-passing portion 60 opens, the water vapor in the storage space 11 passes through the steam release passage 62 and is discharged to the outside of the steam-passing pouch 10. By discharging the water vapor, the pressure increase in the storage space 11 is suppressed, and the steam-passing pouch 10 is prevented from breaking.

<How to open>
Next, a method of opening the steam-passing pouch 10 will be described. First, the steam-passing pouch 10 is placed in a microwave oven with the bottom member sheet 23 facing down and the pouch 10 standing upright. Next, the contents are heated using the microwave oven. This increases the temperature of the contents 15, and the moisture contained in the contents 15 evaporates, increasing the pressure in the storage section 11. When the pressure in the storage section 11 increases, the front sheet 21 and the back sheet 22 expand outward, applying a force to the steam release seal section 61 of the steam-passing section 60, causing the steam release seal section 61 to peel off. This allows the steam in the storage section 15 to escape to the outside through the steam release passage 62 of the steam-passing section 60.

Next, after cooking in the microwave oven, when the pouch is torn from top to bottom at the opening part, if the pouch is heated and swollen, it is difficult to apply force to open it, so an easy-to-open line 52 is required to guide the tearing from the notch 51. At this time, there may be gripping parts 53, 54 above and below the notch 51, and the sheet is torn in the width direction along the easy-to-open line 52 by gripping the gripping parts 53, 54 with the fingers of both hands, with the notch 51 as the starting point for tearing. This allows the steam-permeable pouch 10 to be opened to form an opening at the top, as shown in Figure 4.

Incidentally, when a square-bottom steam-passing pouch 10 with a square-shaped bottom is heated in a microwave oven, the width of the gusset portion of the bottom member sheet 23 of the steam-passing pouch 10 may increase as the pressure in the storage section 11 of the steam-passing pouch 10 increases. In this way, the square-bottom type is preferable because it has good bottom opening properties when heated and can stand stably.

If the bottom opening is good and the pouch can stand stably, when the steam-permeable pouch 10 is opened to form an opening at the top, the width of the opening is enlarged, improving the ease of removing the contents. This makes it possible, for example, to eat the contents contained in the steam-permeable pouch 10 as is using a spoon or the like, without transferring the contents to another container such as a plate. Of course, the contents contained in the steam-permeable pouch 10 may also be removed to another container such as a plate. In this case, the ease of removing the contents can also be improved by enlarging the width of the opening of the steam-permeable pouch 10.

Using samples from the examples and comparative examples, tests were conducted to confirm the relationship between the layer structure of the laser-processed body member sheet 20 and its microwave cooking properties and opening properties. The samples were retort pouches containing curry. The samples were heated and cooked in a 600W microwave for 1 minute, and then a sensory evaluation was performed to see if there were any problems during microwave cooking and to see how easy it was to open the body member sheet 20 when it was torn apart. The layer structure was transparent vapor-deposited PET12/PET12/CPP60. A carbon dioxide laser with a wavelength of 10.6 μm was used for the laser processing. The meanings of the terms related to the materials are as follows:

<Transparent vapor-deposited PET12>
A transparent deposition film in which aluminum oxide is deposited on a polyethylene terephthalate film (thickness 12 μm).

<PET12>
Polyethylene terephthalate film (thickness 12 μm).

<CPP60>
Heat-resistant unoriented polypropylene film (thickness 60 μm).

As can be seen from the results of Examples 1 to 3 in Table 1, when laser processing was performed only on the PET 12, which is the middle layer of the body member sheet 20, microwave cooking was possible regardless of whether the shape of the cut was linear or perforated, and whether the number of cuts was one or more in the standard height direction, and linear cuts were also possible in terms of openability. When laser processing was performed on the outermost layer, the transparent vapor-deposited PET 12, as in Comparative Example 1, openability was good but the gas barrier properties were reduced, resulting in poor microwave cooking. In Comparative Example 2, where laser processing was not performed, microwave cooking was good, but openability was poor and the contents could not be removed.

As described above, the steam-permeable pouch of the present invention provides the following actions and effects. When the contents are contained in the storage space and the closed steam-permeable pouch is heated, a steam vent passage that connects the storage space to the outside is formed in the steam-permeable portion as the pressure in the storage space increases. As a result, water vapor in the storage space passes through the steam vent passage and is discharged to the outside of the steam-permeable pouch, suppressing the increase in pressure in the storage space.

In addition, when the middle layer of the body material sheet is laser processed, the body material sheet can be easily and neatly torn by hand from the opening part. This makes it easy to remove the contents from the opening. Also, if the bottom is molded into a square bottom, the bottom opens easily and the pouch stands upright more stably. When the pouch is opened to form an opening at the top, the width of the opening is expanded, making it easier to remove the contents.

10... Steam-permeable pouch 11... Storage space 15... Contents 20... Body member sheet 20A... Outermost layer of body member sheet 20B... Middle layer of body member sheet 20C... Body member sheet sealant layer 20D... First adhesive layer of body member sheet 20E... Second adhesive layer of body member sheet 21... Front sheet 22... Back sheet 23... Bottom member sheet 31... Top seal portion 32... Bottom seal portion 33... Right side seal portion 34... Left side seal portion 50... Opening portion 51... Notch 52... Easy-open line 52A... Cut 53... Grip portion 54... Grip portion 60... Steam-permeable portion 61... Tip of steam-permeable portion 62... Steam release passage

Claims (7)

The bag comprises two opposing body member sheets and a bottom member sheet that is folded onto the bottom surface,
the left side surface, the right side surface and the bottom surface are sealed at their peripheries to form respective sealed portions, and the contents are filled from the top of the body member sheet and then the top is hermetically sealed to provide a storage space for storing the contents;
A steam-passing pouch having a steam passage portion for releasing steam in the storage space when heated in at least one of the left and right side seal portions, and an opening portion on a bottom surface side below the steam passage portion and substantially parallel to the bottom surface,
The body member sheet includes an outermost layer, an intermediate layer, and a sealant layer made of a non-stretched film, in this order;
The steam-passing pouch is characterized in that an easy-open line is formed in the intermediate layer in the opening portion. The steam-permeable pouch according to claim 1, characterized in that the easy-open line is formed continuously or intermittently by laser processing. The steam-passing pouch according to claim 1 or 2, characterized in that at least one of the left and right side seals has a notch on the bottom side below the steam-passing section, and the notch is formed so that its tip is located on an imaginary line extending from the easy-open line. The steam-passing pouch according to any one of claims 1 to 3, characterized in that the sealant layer of the body member sheet is made of a material that is heat-resistant and easily tearable in the width direction. The steam-passing pouch according to any one of claims 1 to 4, characterized in that the material constituting the sealant layer is unstretched polypropylene. The steam-passing pouch according to any one of claims 1 to 5, in which the bottom member sheet is folded between the two opposing body member sheets, and then formed and sealed in a manner that has a gusset portion, and the bottom is formed into a square bottom. The steam-passing pouch according to any one of claims 1 to 6, wherein the outermost layer is made of a polyethylene terephthalate film on which an inorganic thin film is vapor-deposited.