Method for manufacturing packaging body

Abstract

To provide technology enabling high-speed manufacturing of packaging bodies equipped with packaging bags having a dehumidification function.SOLUTION: A method for manufacturing a packaging body according to the present invention comprises: a first process of forming a first joint portion 33 on a sheet 4 during transport, and forming the sheet 4 into a tubular shape to obtain a tubular sheet 41 that contains a contained object 2; and a second process of partially applying a bonding treatment using heating and pressurizing means to the tubular sheet 41 during transport, thereby forming a plurality of second joint portions 34 extending in a direction intersecting with a transport direction MD of the tubular sheet 41 intermittently in the transport direction MD. In the second step, the plurality of heating and pressurizing means 6A, 6B are used as the heating and pressurizing means, and for each of a plurality of predetermined locations 34P for forming the second joint portions 34 in the tubular sheet 41, the plurality of heating and pressurizing means 6A, 6B, intermittently arranged in the transport direction MD, are used in sequence starting from the heating and pressurizing means located upstream in the transport direction MD to apply the bonding treatment.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a package provided with a pillow packaging bag having a desteaming function. [Background technology]

[0002] With the increasing popularity of microwave ovens, pre-cooked frozen foods that can be easily heated with microwaves to achieve an authentic taste are now commercially available. These types of frozen foods are typically sold sealed in a vapor-impermeable packaging container. When such packaged frozen foods are heated in a microwave-resistant container, gases such as water vapor generated by the frozen food during heating accumulate inside the container without escaping to the outside, causing an increase in the internal pressure of the container and potentially resulting in problems such as the container bursting or the contents of the frozen food scattering. Therefore, it has been common practice to open the packaging bag, remove the frozen food, cover the frozen food with plastic wrap, and then microwave-heat the food. However, these pre-heating steps are tedious, and improvements in the convenience of packaged frozen foods are desired.

[0003] In response to this, packaging containers have been proposed that have a desteaming function that releases steam when the internal pressure exceeds a certain value. Patent Documents 1 and 2 describe pillow packaging bags with a desteaming function that have a desteaming section in a sealed section, such as an end seal section or a center seal section, that is closed when unheated but automatically opens when the internal pressure increases due to microwave heating. The open desteaming section functions as an outlet for steam inside the pillow packaging bag. The desteaming section is, for example, a weakly sealed section that has weaker seal strength than the surrounding section, and is configured to automatically open when microwave heating or the resulting increase in internal pressure of the pillow packaging bag is triggered by the release of the bond between the sheets in the desteaming section (weakly sealed section). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-302165 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-217050 Summary of the Invention [Problem to be solved by the invention]

[0005] Pillow packaging bags are typically manufactured through the following process: First, a long, strip-shaped packaging sheet is continuously unwound from a roll and conveyed, and both side edges of the packaging sheet along the conveying direction (MD) are folded back toward the center in the direction perpendicular to the MD (CD) while being conveyed, and the both side edges are overlapped and heat-sealed in a folded state to form a center seal portion to obtain a long, strip-shaped tubular sheet, next, the tubular sheet is intermittently heat-sealed in the MD to form a plurality of end seal portions extending in the CD, and finally, the tubular sheet is cut at the end seal portions to obtain a pillow packaging bag that encloses an accommodation portion for the accommodation item between the pair of end seal portions and has the center seal portion at the back surface.

[0006] When the conveyance speed of the packaging sheet is increased to produce pillow packaging bags with a desteaming section in the sealed area that automatically opens when heated in a microwave oven, as described in Patent Documents 1 and 2, using a typical pillow packaging bag manufacturing process at high speed, the heating temperature during heat sealing must be higher than at lower conveyance speeds to compensate for insufficient heating of the area where the seal is to be formed due to the increased conveyance speed. However, forming the seal under such high-speed and high-temperature conditions can result in uneven seal strength in the sealed area, and the seal strength of the area other than the desteaming section may be lower than the designed strength. When a pillow packaging bag manufactured at high speed is heated in a microwave oven, the area other than the desteaming section may automatically open before the desteaming section. This can cause problems such as uneven heating and burning of the contents inside the pillow packaging bag, and can also cause users of the pillow packaging bag to unknowingly touch the opening in the area other than the desteaming section and be burned. A technology for high-speed production of pillow packaging bags with desteaming functionality has not yet been developed.

[0007] An object of the present invention is to provide a technology that enables high-speed production of packaging bodies equipped with packaging bags having a desteaming function. [Means for solving the problem]

[0008] The present invention provides a package comprising an object to be contained and a vapor-impermeable packaging bag that contains a storage section and stores the object in the storage section in a sealed state, The packaging bag has a front portion formed of a sheet and a back portion formed of the sheet, and a first joint portion formed on the back portion by joining both side edge portions of the sheet in one direction, and a pair of second joint portions formed by joining opposing sheets to each other extend at both ends in the extending direction of the first joint portion in a direction intersecting the first joint portion, and the storage portion is located between one and the other of the pair of second joint portions, A method for manufacturing a packaging body, wherein a devaporation section that discharges water vapor inside the packaging bag to the outside is disposed in at least one of the pair of second joints, and the devaporation section is closed when the packaging body is not heated, but is configured to automatically open when the packaging body is heated due to an increase in internal pressure of the packaging bag caused by water vapor generated from the contained items, a first step of conveying the belt-shaped sheet, folding back both side edge portions along the conveying direction of the sheet to one side of the sheet, and overlapping and joining the both side edge portions to form the first joining portion, thereby forming the sheet into a cylindrical shape and obtaining a cylindrical sheet containing the contents to be contained; a second step of partially applying a joining process using a heating and pressurizing means to the cylindrical sheet during conveyance to join the opposing sheets in the joining process area, and forming a plurality of second joining portions extending in a direction intersecting the conveyance direction of the cylindrical sheet at intervals in the conveyance direction; In the second step, the method for manufacturing a packaging body performs the joining process on each of the locations on the tubular sheet where the second joining portions are to be formed, using multiple heating and pressurizing means that are intermittently arranged in the conveying direction of the tubular sheet, in order from the one located upstream in the conveying direction. [Effects of the Invention]

[0009] According to the method for producing a package of the present invention, a package provided with a packaging bag having a desteaming function can be produced at high speed. In a package manufactured by the method for manufacturing a package of the present invention, a packaging bag for hermetically storing an item to be contained is provided with a desteaming section that automatically changes from a closed state to an open state when the internal pressure of the packaging bag increases due to heating such as microwave heating, and therefore problems such as the packaging bag bursting are unlikely to occur even when the item to be contained is heated together with the packaging bag. Therefore, for example, if the item to be contained is a frozen food, the frozen food can be made edible by simply heating the package in a microwave oven. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic perspective view of one embodiment of a package manufactured by the method for manufacturing a package of the present invention. [Figure 2] FIG. 2 is a cross-sectional view schematically showing a cross section taken along line II in FIG. 1 (a cross section along the longitudinal direction and thickness direction of the packaging body). [Figure 3] FIG. 3 is a diagram showing a packaging bag constituting the package shown in FIG. 1, and is a perspective view schematically showing the back side of the packaging bag in a folded state. [Figure 4] Figure 4 is a diagram illustrating the general configuration of one embodiment of the method for manufacturing a packaging body of the present invention, where Figure 4(a) is a schematic side view of a sheet along the conveying direction in which an item to be contained is placed on one side of the sheet during conveyance, Figure 4(b) is a schematic plan view of a tubular sheet obtained by folding the sheet during conveyance to form a first joint, and Figure 4(c) is a schematic cross-sectional view of the tubular sheet along the conveying direction in which a second joint is formed on the tubular sheet during conveyance. DETAILED DESCRIPTION OF THE INVENTION

[0011] First, a description will be given of a package, which is the object of the manufacturing method of the package of the present invention. Figures 1 and 2 show a package 1, which is one embodiment of the package of the present invention. The package 1 includes an object 2 to be contained, and a vapor-impermeable packaging bag 3 that contains a storage section 30 and stores the object 2 in the storage section 30 in a sealed state.

[0012] The contained item 2 includes a steam-generating body that generates water vapor when the unopened package 1 is heated. The steam-generating body is typically a food product, and a specific example is a frozen food product. Frozen foods are available in both uncooked and cooked forms, and both can be used in the present invention. Uncooked frozen foods require cooking, such as seasoning, cutting, and heating, to be ready for consumption, but cooked frozen foods do not require cooking. The foods that make up the cooked frozen food are not particularly limited as long as they are microwave-heatable, and may be, for example, noodles, rice dishes, main dishes, or side dishes. Examples of the types of noodles include pasta (e.g., spaghetti, macaroni, penne, ravioli, etc.), udon, soba, and Chinese noodles. The frozen food 2 may be a frozen product of one type of food, or two or more types of food. A specific example of the latter is a one-plate frozen food consisting of a staple food (noodles, rice dishes, etc.) and a side dish.

[0013] When the contents 2 contain cooked frozen food, the cooked frozen food is thawed and made ready to eat by microwave heating the package 1 using a microwave cooking appliance such as a microwave oven. In this case, the package 1 can be said to be a packaged frozen food for microwave cooking.

[0014] The contained item 2 is only required to include the steam-generating element, and may also include something other than the steam-generating element. In this embodiment, as shown in Fig. 2, the contained item 2 includes a steam-generating element 21 and an inner container 22 that accommodates the steam-generating element 21.

[0015] In this embodiment, the steam-generating body 21 is cooked frozen noodles, which is a type of cooked frozen food. Specifically, as shown in Fig. 2, the steam-generating body 21 is frozen spaghetti, and is composed of a cooked frozen spaghetti and a cooked frozen pasta sauce placed on top of it, with the two frozen bodies being integrated together.

[0016] The material of the inner container 22 is not particularly limited, and examples thereof include paper, resin, and a composite material combining these. The shape of the inner container 22 is also not particularly limited, and examples thereof include a tray and a bag-shaped container. In this embodiment, the inner container 22 is a tray, and has a bottom wall 23 and a peripheral wall 24 that is rectangular in plan view and extends from the peripheral edge of the bottom wall 23.

[0017] The packaging bag 3 is a pillow packaging bag formed by molding a sheet 4 into a bag shape and sealing the edges, and has a front portion 31 formed by the sheet 4 and a back portion 32 formed by the sheet 4. As shown in FIG. 3, the back portion 32 has a first joint portion 33 formed by joining both side edges of the sheet 4 in one direction. At both ends of the first joint portion 33 in the extending direction of the packaging bag 3, a pair of second joint portions 34, 34 formed by joining opposing sheets 4 extend in a direction intersecting (more specifically, perpendicular to) the first joint portion 33. A storage portion 30 for the item 2 to be contained is located between one and the other of the pair of second joint portions 34, 34.

[0018] In this embodiment, the packaging bag 3 has a rectangular shape in a plan view and has a longitudinal direction X and a width direction Y perpendicular to the longitudinal direction X. The longitudinal direction X of the packaging bag 3 is the machine direction (MD) of the packaging body 1 or its raw material (sheet 4) or intermediate product (a tubular sheet 41 described later) during production of the packaging body 1, and the width direction Y of the packaging bag 3 is the cross-machine direction (CD) perpendicular to the machine direction (MD). The first joint 33 is located in the center of the back surface portion 32 of the packaging bag 3 in the width direction Y and extends in the same direction over the entire length of the packaging bag 3 in the longitudinal direction X. The pair of second joints 34, 34 each extend in the same direction over the entire length of the packaging bag 3 in the width direction Y. The second joint 34 is a short side edge of the packaging bag 3 that is rectangular in a plan view. On the other hand, at the long side edge of the packaging bag 3 that is rectangular in a plan view, the sheets 4 that make up the long side edge are not joined together.

[0019] At the first joint 33, both side edge portions of the sheet 4 along the longitudinal direction X are joined together in a folded manner. At the second joint 34, both side edge portions of the sheet 4 along the width direction Y are joined together. The first joint 33 is not joined to other parts of the packaging bag 3, and as shown in Figure 3, is rotatable around its base end. The base end is the end opposite to the tip end of the first joint 33 along the longitudinal direction X, and is the part of the first joint 33 that forms the boundary between the first joint 33 and parts of the packaging bag 3 other than the first joint 33.

[0020] In the present invention, the method for joining the sheets 4 at the first joint portion 33 and the second joint portion 34 is not particularly limited, and examples thereof include fusion bonding and adhesive. Typically, fusion bonding is performed by heat sealing, ultrasonic sealing, etc. In the present embodiment, fusion bonding by heat sealing is used.

[0021] In this embodiment, as shown in FIG. 1 , ridges 35 and grooves 36 extending in the extension direction (width direction Y) of the second joint 34 are alternately formed in the second joint 34 in a direction perpendicular to the extension direction. The second joint 34, in which the ridges 35 and grooves 36 are formed, has a wavy cross section in a direction perpendicular to the extension direction. When the second joint 34 has such a wavy cross section, the strength is improved compared to when the second joint 34 is not wavy. This prevents problems such as unintentional opening of the second joint 34 during transportation or storage of the package 1 and release of the sheets 4 from each other in a portion of the second joint 34 where a desteaming unit 5 (described later) is not disposed when the package 1 is heated for use (for example, when the package 1 is heated in a microwave oven to prepare the package 2 for consumption if the package 2 is a frozen food).

[0022] 3, the first bonding portions 33 are also wavy like the second bonding portions 34. Specifically, the first bonding portions 33 are formed with ridges 35 and grooves 36 extending in the extension direction (longitudinal direction X) of the first bonding portions 33, alternately arranged in a direction perpendicular to the extension direction.

[0023] At least one of the pair of second joints 34, 34 is provided with a desteaming section 5 that discharges water vapor from inside the packaging bag 3 to the outside. In this embodiment, as shown in Figures 1 and 3, a desteaming section 5 is provided in both of the pair of second joints 34, 34.

[0024] The devaporation section 5 is closed when the packaging body 1 is in an unheated state (unused state), but when the packaging body 1 is heated, the internal pressure of the packaging bag 3 increases due to steam generated from the contained item 2 (steam-generating body 21), and the devaporation section 5 is designed to automatically open. Here, "automatically opens" means that the devaporation section 5 opens without any manual operation. In other words, the inside and outside of the packaging body 1 are not always in communication via the devaporation section 5, but rather the inside and outside become in communication via the devaporation section 5 only when the packaging body 1 is heated.

[0025] As described above, the devaporation section 5 is closed when the packaging body 1 is in an unheated state, and "closed" here includes a state in which, when the packaging body 1 is in an unheated state, communication between the inside and outside of the packaging bag 3 at the devaporation section 5 is completely blocked (a completely closed state), and a state in which the inside and outside of the packaging bag 3 are in communication at the devaporation section 5 but water vapor cannot be discharged to the outside via the devaporation section 5 (an incompletely closed state). An example of the incompletely closed state is a state in which an opening has an extremely small diameter, allowing gases such as oxygen to pass through but preventing water vapor from passing through. When the packaging body 1 is heated and the internal pressure of the packaging bag 3 increases, the devaporation section 5 in the incompletely closed state "automatically opens" as the surrounding sheet 4 that defines the opening tears starting from the opening. A packaging bag 3 having a devaporation section 5 in an incompletely closed state is susceptible to problems such as breakage originating from the devaporation section 5 during transportation and storage, or the introduction of foreign matter into the packaging bag 3 through the devaporation section 5. Therefore, in order to eliminate such concerns, a devaporation section 5 in a completely closed state is preferred.

[0026] According to the packaging body 1, the packaging bag 3 is provided with a devaporation section 5, which makes it easy to heat the contained item 2. Specifically, due to the presence of the devaporation section 5, even if gas such as water vapor is generated from the contained item 2 (steam-generating element 21) when the packaging body 1 is heated, the gas is discharged to the outside of the packaging bag 3 via the devaporation section 5. In particular, in this embodiment, the position of the devaporation section 5 is the second joint section 34, which is a short side edge of the packaging bag 3, and this is the area where the expansion force is most concentrated when the packaging bag 3 expands in response to an increase in the internal pressure of the packaging bag 3 (storage section 30), which has a rectangular shape in a plan view. Therefore, the devaporation section 5 smoothly changes from a closed state to an open state in response to an increase in the internal pressure of the packaging bag 3, and the inconvenience of the sheets 4 being released from the joint in the area where the devaporation section 5 is not located is prevented. Therefore, when heating the contained item 2, there is no need to open the packaging bag 3 and remove the contained item 2, and the entire package 1 can be heated with the packaging bag 3 remaining unopened, allowing the contained item 2 to be easily heated without causing inconveniences such as the packaging bag 3 bursting or the contained item 2 scattering. Furthermore, by providing the packaging bag 3 with the desteaming section 5, an inner bag with a desteaming function used to package the contained item 2 inside the packaging bag 3 is no longer necessary, thereby reducing the manufacturing cost of the package 1.

[0027] In particular, in this embodiment, since a devaporation section 5 is arranged at both of the pair of second joints 34, 34, even if one of the devaporation sections 5 does not automatically open due to an increase in the internal pressure of the packaging bag 3 for some reason (for example, a manufacturing defect, physical blockage of the devaporation section 5 by the contents of the packaging bag 3, etc.), there is a high probability that the other devaporation section 5 will function normally, and water vapor from within the packaging bag 3 can be discharged more stably.

[0028] In this embodiment, as shown in FIG. 1 , one devastation section 5 is disposed in the center in the direction in which the second joint 34 extends (the width direction Y of the packaging body 1). In the present invention, the number and arrangement of the devastation sections 5 are not particularly limited and can be adjusted as appropriate as long as the effects of the present invention are not hindered. For example, multiple devastation sections 5 may be disposed intermittently in the direction in which the second joint 34 extends. Furthermore, when devastation sections 5 are disposed in both of a pair of second joints 34, 34, the arrangement pattern of the devastation sections 5 (the number and positions of the devastation sections 5) may be the same or different between one second joint 34 and the other second joint 34, as in this embodiment.

[0029] In FIG. 1 , a pattern consisting of multiple diagonal lines is applied to the deevaporation section 5 for the purpose of clarifying the position of the deevaporation section 5, but in an actual package, the deevaporation section does not necessarily have a pattern applied to it. In the present invention, the deevaporation section 5 may be patterned or colored, for example, to make it possible to visually distinguish the deevaporation section 5 from its surrounding area. This makes it possible to alert the user of the package 1 to the presence of the deevaporation section 5 and provide the user with information useful for handling the package 1.

[0030] The desteaming section 5 can be a region where the bond strength between the multiple sheets 4 (both side edge portions along the width direction Y of the sheets 4) is always lower than in a portion of the second bonding section 34 where the desteaming section 5 is not disposed. Hereinafter, this type of desteaming section will also be referred to as a "desteaming section with reduced bond strength." When the devaporation section 5 is a devaporation section with reduced bonding strength, when the packaging body 1 is heated in a microwave oven or the like during use and the internal pressure of the packaging bag 3 increases, the bonding between the sheets 4 in the devaporation section 5, which has a relatively low bonding strength, is released at the second bonding section 34, causing the devaporation section 5 to automatically open, but in the non-positioning section of the devaporation section 5, which has a higher bonding strength than the devaporation section 5, the bonding between the sheets 4 is not released.

[0031] The bond strength-reducing desteaming section can be formed by partially varying the bond strength between the sheets 4 in the second joint 34. When the second joint 34 is formed by a known sealing method such as heat sealing or ultrasonic sealing, the bond strength can be adjusted by shortening the heating time, lowering the heating temperature, or shortening the seal width (the length in the direction perpendicular to the extending direction of the second joint 34) in the area where the desteaming section 5 is to be formed compared to the area where the desteaming section 5 is not to be formed. Another method for adjusting the bond strength is to interpose a sealant layer made of a material that reduces the bond strength between the sheets 4 between the opposing sheets 4 in the area where the desteaming section 5 is to be formed in the second joint 34, and not to dispose the sealant layer in the area where the desteaming section 5 is not to be formed in the second joint 34. The "material that reduces the bonding strength between sheets 4" may be, for example, a resin that has a higher melting point than sheet 4 and is unlikely to exhibit adhesive properties even when heated to a temperature at which sheet 4 can exhibit sufficient adhesive properties.

[0032] When the devastation section 5 is the above-mentioned bond strength reducing type devastation section, the ratio of the bond strength between the sheets 4 in the closed state of the devastation section 5 to the bond strength between the sheets 4 in the non-placement portion of the devastation section 5 in the second bond section 34 is preferably 15 to 33%, more preferably 20 to 30%. When the desteaming section 5 is the bond strength reducing type desteaming section, the bond strength between the sheets 4 in the closed state of the desteaming section 5 is preferably 3 to 8 N, and more preferably 4 to 6.5 N. The bonding strength can be measured by a method in accordance with JIS Z 1707 "General rules for food-use plastic films" 7.4 "Heat seal strength test".

[0033] The desteaming section 5 may also be a section where the bonding between the multiple sheets 4 (both side edge portions of the sheets 4 along the width direction Y) that make up the desteaming section 5 or its peripheral portion is released by heating. Hereinafter, this type of desteaming section is also referred to as a "thermal change type desteaming section." When the devaporation section 5 is a heat-change type devaporation section, when the packaging body 1 is heated for the purpose of its use, for example, when the contained item 2 is a frozen food, it is heated in a microwave oven to make the contained item 2 edible, the devaporation section 5 automatically opens at the second joint 34 as the bonding between the sheets 4 is released in the devaporation section 5 or its surrounding area, but the bonding between the sheets 4 is not released in the non-positioned areas of the devaporation section 5.

[0034] Desteaming section 5, which is the heat change type desteaming section, can be formed by selectively using a heat changeable material whose properties change when heated (for example, heated in a microwave oven) to which package 1 is subjected during use, in a portion of second joint 34 where desteaming section 5 is to be formed. Specifically, for example, a material that softens (weakens) faster than sheet 4 when heated in a microwave oven is used as the heat changeable material, and a sealant layer made of this material is interposed between opposing sheets 4 in the portion of second joint 34 where desteaming section 5 is to be formed, while no sealant layer is disposed in portions of second joint 34 where desteaming section 5 is not to be formed. Another method for forming the heat-changeable desteaming section 5 is to selectively apply the heat-changeable material, which chemically or physically weakens adjacent layers of sheet 4 when heated by heat sealing or the like, to a location in second joint 34 where desteaming section 5 is to be formed, prior to the step of forming second joint 34 during the manufacture of packaging 1. In an unused (unheated) state of packaging 1 manufactured by the other method, in desteaming section 5 in second joint 34, the sheets 4 are released from bonding to each other, or the bonding strength between the sheets 4 is reduced compared to a portion of second joint 34 where desteaming section 5 is not placed.

[0035] The sheet 4 constituting the packaging bag 3 is non-vapor permeable, which prevents gases such as water vapor from moving between the inside and outside of the packaging bag 3. Therefore, when the packaging body 1 is heated by microwaves, gases such as water vapor generated from the contained item 2 by the heating do not escape to the outside of the packaging bag 3 but accumulate inside (containing section 30), causing the internal pressure of the packaging bag 3 to increase.

[0036] Microwave transparency, heat resistance, and water resistance are required for the sheet 4. Materials that satisfy these required properties are preferred for the sheet 4, and examples thereof include heat-resistant plastics such as nylon, polyethylene terephthalate, crystallized polyethylene terephthalate, polypropylene, polyethylene, and polystyrene; paper that is partially or entirely coated with a heat-resistant and water-resistant coating; and composite materials that combine two or more of these.

[0037] Next, a method for manufacturing the package of the present invention will be described using the method for manufacturing the package 1 described above as an example. Figure 4 shows the main steps of the manufacturing process for the package 1. The method for manufacturing the package 1 includes a first step and a second step that is carried out after the first step.

[0038] In the first step, as shown in Figure 4(a), first, the sheet 4 is continuously unwound from a roll 40 of long, strip-shaped sheet 4 wound into a roll to transport the strip-shaped sheet 4, and as shown in Figure 4(b), the side edge portions 4S, 4S of the sheet 4 being transported along the transport direction MD are folded back toward one side 4a of the sheet 4, and the side edge portions 4S, 4S are overlapped and joined to form a first joint portion 33, and the sheet 4 is formed into a cylindrical shape to obtain a long, strip-shaped cylindrical sheet 41 that contains the contents 2 (steam generator 21 and inner container 22) inside.

[0039] The first step can be carried out essentially in the same manner as the step of manufacturing a tubular sheet in a conventional method for manufacturing a pillow packaging bag. For example, the formation of the first bonded portion 33 can be carried out in a conventional manner using a known heating and pressurizing means such as a heat sealing device or an ultrasonic sealing device.

[0040] In the first step, the method for enclosing the objects 2 in the tubular sheet 41 is not particularly limited. In this embodiment, as shown in FIG. 4(a), multiple objects 2 are intermittently conveyed in a conveying direction MD by a conveying means such as a belt conveyor (not shown), and the sheet 4 is conveyed in the same direction MD, joining the multiple objects 2 from their upper surfaces. One surface (lower surface) 4a of the sheet 4 is then brought into contact with the objects 2. Then, as shown in FIG. 4(b), both side edge portions 4S, 4S of the sheet 4 are folded back toward the contact surface 4a of the sheet 4 that contacts the objects 2. The both side edge portions 4S, 4S are then overlapped and joined to form a first joint portion 33, thereby obtaining the tubular sheet 41. Note that FIG. 4(b) is a plan view of the tubular sheet 4 as viewed from the side where the first joint portion 33 is formed. As described above, instead of the method of bending the sheet 4, with the objects to be contained 2 in contact with one surface 4a, into a cylindrical shape so as to surround the objects to be contained 2 inside, and then forming the first joint 33, a method can be adopted in which a tubular sheet 41 that does not contain the objects to be contained 2 is formed, and then the objects to be contained 2 are inserted into the tubular sheet 41. That is, both side edge portions 4S, 4S of the sheet 4 being conveyed are folded back toward the one surface 4a, and the both side edge portions 4S, 4S are overlapped and joined to form the first joint 33, thereby obtaining a long strip-shaped tubular sheet 41, and then a plurality of objects to be contained 2 can be intermittently supplied into the tubular sheet 41 in the conveying direction MD, thereby obtaining a long strip-shaped tubular sheet 41 that contains the objects to be contained 2.

[0041] In the second step, the tubular sheet 41 being conveyed through the first step is partially subjected to a joining process using a heating and pressurizing means to join opposing sheets 4 in the area to be joined, and multiple second joints 34 extending in a direction intersecting the conveyance direction MD of the tubular sheet 41, more specifically, in a direction crossing the conveyance direction MD of the tubular sheet 41, more specifically, in a direction perpendicular to the conveyance direction CD perpendicular to the conveyance direction MD, are formed intermittently in the conveyance direction MD. The planned formation positions 34P of the second joints 34, which are the areas on the long strip-shaped tubular sheet 41 that are subjected to the joining process, are located between two adjacent objects 2, 2 in the conveyance direction MD of the tubular sheet 41, as shown in FIG. 4(b).

[0042] As described above, the desteaming section 5 is disposed in the second joint 34. The method of forming the desteaming section 5 is as described above, and by adopting a method such as partially varying the bonding strength between the sheets 4 in the second joint 34 or selectively using a special material (the thermally changeable material, the special ink, etc.) in a region 34P in the second joint 34 where the desteaming section 5 is to be formed, in accordance with the type of desteaming section 5 to be formed (the bond strength reduction type desteaming section or the heat change type desteaming section), and by performing the bonding treatment on the region 34P in the second joint 34 where the desteaming section 5 is to be formed, the second joint 34 in which the desteaming section 5 is disposed can be formed in the region 34P where the desteaming section 5 is to be formed.

[0043] The method for manufacturing a package according to the present invention is characterized in that, in the second step, as shown in Fig. 4(c), a joining process is performed on each of the predetermined formation regions 34P of the plurality of second joining regions 34 on the tubular sheet 41 using a plurality of heating and pressurizing means arranged at intervals in the conveying direction MD of the tubular sheet 41, in order from the one located upstream in the conveying direction MD. That is, in the method for manufacturing a package according to the present invention, the formation regions 34P of the second joining regions 34, which correspond to the end seal portions, are joined multiple times. This is in contrast to the method for manufacturing a typical pillow packaging bag, in which the formation regions of the end seal portions are joined only once (heating and pressurizing).

[0044] 4(c), the plurality of heating and pressing means include two heating and pressing means: a heating and pressing means 6A arranged upstream in the conveying direction MD, and a heating and pressing means 6B arranged downstream in the conveying direction MD. Therefore, in the present embodiment, each of the predetermined formation sites 34P of the plurality of second bonding portions 34 is subjected to two bonding processes, that is, a bonding process by the heating and pressing means 6A and a bonding process by the heating and pressing means 6B in that order.

[0045] The heating and pressing means 6A, 6B each include a pair of pressure-bonding bodies 61, 62 arranged opposite to each other, and are capable of heating and pressing the cylindrical sheet 41 introduced between one pressure-bonding body 61 and the other pressure-bonding body 62. The pressure-bonding bodies 61, 62 each include a cylindrical heating roll that rotates about a horizontal axis, and a heating means such as a heater that heats the outer circumferential surface of the heating roll. The outer circumferential surface of the heating roll is heated to a predetermined temperature by the heating means, and the heated outer circumferential surface comes into contact with the workpiece (cylindrical sheet 41).

[0046] According to the manufacturing method of the present invention, second joints 34 are formed by performing a joining process using a heating and pressurizing means multiple times on each of multiple planned formation locations 34P of second joints 34 on tubular sheet 41 during transport, so second joints 34 with desteaming units 5 can be stably formed, and packages 1 including packaging bags 3 with desteaming functions can be manufactured at high speed. If the joining process is performed only once on the planned formation locations of end seals, as in a typical manufacturing method for pillow packaging bags, when the conveying speed of the raw material sheet is increased for the purpose of high-speed manufacturing of pillow packaging bags, the heating temperature in the joining process must be increased to compensate for insufficient heating of the planned formation locations of end seals that occurs due to the increased conveying speed. However, manufacturing pillow packaging bags under such high-speed and high-temperature conditions could damage the planned formation locations of end seals, depending on the material of the raw material sheet. In contrast, in the manufacturing method of the present invention, the joining process is performed multiple times on the area scheduled to form second joining portion 34, which corresponds to the end seal portion, so there is no need to set the heating temperature for each joining process to a high temperature that would raise concerns about damage to raw material sheet 4, and it can be set to a relatively low temperature that does not pose such concerns, making it possible to manufacture packaging bags 3 under high-speed, low-temperature conditions. Furthermore, in the packaging body 1 manufactured by the manufacturing method of the present invention, at second joining portion 34 with devastation section 5, the joining strength of devastation section 5 and other portions is at a practically sufficient level as designed, so that when heated in a microwave oven, only devastation section 5 automatically opens, and the problem of portions other than devastation section 5 automatically opening before devastation section 5 is unlikely to occur.

[0047] According to the investigations of the inventors, in the manufacturing method of the packaging body 1 shown in Figure 4 (a manufacturing method in which the bonding process is performed twice on the region 34P where the second bonding portion 34 is to be formed in the second step), when the second step is modified to use only one heating and pressing means (only one of the two heating and pressing means 6A, 6B) in accordance with the manufacturing method of a general pillow packaging bag and to perform the bonding process only once on the region 34P where the second bonding portion 34 is to be formed, and when the target value of the bonding strength of the devastation portion 5 in the second bonding portion 34 is set to 5 N and the target value of the bonding strength of the region other than the devastation portion 5 is set to 20 N, in order to achieve these target values, it was necessary to ensure a bonding process time by the single heating and pressing means (the contact time between the heating and pressing means and the tubular sheet 41, which is the workpiece) of 0.210 seconds. In contrast, according to the manufacturing method of the packaging body 1 shown in Fig. 4, the target value was achieved even when the time for each of the two joining processes using the two heating and pressurizing means 6A and 6B was set to 0.105 seconds. This shows that according to the manufacturing method of the packaging body of the present invention, a packaging body provided with a packaging bag having a desteaming function can be manufactured at a higher speed than conventional methods.

[0048] In the second step, the heating temperature of the workpiece (cylindrical sheet 41) in one joining process can be selected appropriately depending on the type of sheet 4, etc., and is not particularly limited, but from the viewpoint of high-speed and stable production, it is preferably 120 to 250°C, more preferably 140 to 230°C.

[0049] The bonding conditions such as the heating temperature may be the same or different between the multiple heating and pressing means 6A, 6B used in the second step. In the present invention, the number of heating and pressing means used in the second step is not particularly limited and may be three or more, and the same applies in that case.

[0050] In this embodiment, as shown in Fig. 1, ridges 35 and grooves 36 are formed in the second joint portion 34, and as shown in Fig. 4(c), each of the multiple heating and pressing means 6A, 6B used in the second step has uneven portions 63 corresponding to the ridges 35 and grooves 36 at the contact portion (the outer peripheral surface of the heating roll) of each of the pair of pressure-bonding bodies 61, 62 with the tubular sheet 41. The uneven portions 63 are arranged in a portion of the circumferential direction of the outer peripheral surface of the heating roll of each of the pair of pressure-bonding bodies 61, 62. As the tubular sheet 41 is conveyed, the uneven portions 63 of one pressure-bonding body 61 and the uneven portions 63 of the other pressure-bonding body 62 simultaneously contact the predetermined formation portion 34P, and the predetermined formation portion 34P can be compressed from both sides thereof. The rotation conditions of the pair of pressure-bonding bodies 61, 62 are adjusted. By compressing the predetermined formation site 34P of the second bonding portion 34 between the pair of concave and convex portions 63, 63, the second bonding portion 34 having the ridge portions 35 and the groove portions 36 is formed.

[0051] In this embodiment, all of the multiple heating and pressing means 6A, 6B have the uneven portion 63, but it is sufficient that at least the one located furthest downstream in the conveying direction MD has the uneven portion 63. If the heating and pressing means 6B located furthest downstream in the conveying direction MD did not have the uneven portion 63 and the heating and pressing means 6A located further upstream in the conveying direction MD did have the uneven portion 63, the ridges 35 and grooves 36 formed in the tubular sheet 41 by the joining process by the heating and pressing means 6A might be crushed by the joining process by the heating and pressing means 6B, which does not have the uneven portion 63 in the contact portion with the tubular sheet 41. From the viewpoint of reliably forming the ridges 35 and grooves 36 in the second joining portion 34, it is preferable that all of the multiple heating and pressing means used in the second step have the uneven portion 63, as in this embodiment.

[0052] In this embodiment, as shown in FIG. 3, the first joint 33 also has ridges 35 and grooves 36 formed therein, and the ridges 35 and grooves 36 of the first joint 33 can be formed in accordance with conventional methods.

[0053] After forming the second joint portion 34 on the tubular sheet 41, or simultaneously with the formation of the second joint portion 34, the tubular sheet 41 is cut in the direction perpendicular to the conveyance direction CD at the second joint portion 34, thereby obtaining a single unit of packaging body 1. The latter "cutting simultaneously with the formation of the second joint portion 34" can be performed, for example, in the packaging body manufacturing method shown in Figure 4 by providing a cutting means such as a cutter to the heating and pressing means 6B located most downstream in the conveyance direction MD, out of the multiple heating and pressing means 6A, 6B used in the second step, and cutting the tubular sheet 41 with the cutting means simultaneously with the joining process of the region 34P where the second joint portion 34 is to be formed by the heating and pressing means 6B.

[0054] The present invention has been described above based on its preferred embodiments, but the present invention is not limited to the above embodiments and can be modified as appropriate within the scope of the invention. For example, in the above embodiment, two heating and pressurizing means were used in the second step, and two bonding processes were performed on each of the planned formation locations 34P of the multiple second bonding portions 34 in the tubular sheet 41, but three or more heating and pressurizing means may be used, and three or more bonding processes may be performed on each planned formation location 34P. [Explanation of symbols]

[0055] 1 package 2. Detainees 21 Steam generator 22 Inner container 3 packaging bag 30 Storage section 31 Front 32 Rear part 33 1st joint 34 Second joint 34P Planned location for forming second joint 35 Ridge 36 Groove 4 seats 41 Cylindrical sheet 5 Devaporation section 6, 6A, 6B Heating and pressurizing means 61,62 Crimping body 63 Uneven part X Longitudinal direction of package Y Width direction of the package MD conveying direction CD: Orthogonal transport direction

Claims

1. A package comprising an object to be contained and a vapor-impermeable packaging bag that contains a storage section and stores the object in the storage section in a sealed state, The packaging bag has a front portion formed of a sheet and a back portion formed of the sheet, and a first joint portion is formed on the back portion by joining both side edge portions of the sheet in one direction, and a pair of second joint portions is formed on both ends in the extending direction of the first joint portion by joining opposing sheets, extending in a direction intersecting the first joint portion, and the storage portion is located between one and the other of the pair of second joint portions, A method for manufacturing a packaging body, wherein a desteaming section that discharges water vapor inside the packaging bag to the outside is disposed in at least one of the pair of second joints, and the desteaming section is closed when the packaging body is not heated, but is configured to automatically open when the packaging body is heated due to an increase in internal pressure of the packaging bag caused by water vapor generated from the contained items, a first step of conveying the belt-shaped sheet, folding back both side edge portions along the conveying direction of the sheet to one side of the sheet, and overlapping and joining the both side edge portions to form the first joint portion, thereby forming the sheet into a cylindrical shape and obtaining a cylindrical sheet containing the contents to be contained; a second step of partially applying a joining process using a heating and pressurizing means to the cylindrical sheet during conveyance to join the opposing sheets in the joined section, and forming a plurality of second joined sections extending in a direction intersecting the conveyance direction of the cylindrical sheet at intervals in the conveyance direction; In the second step, the method for manufacturing a packaging body performs the joining process on each of the locations on the tubular sheet where the second joints are to be formed, using multiple heating and pressurizing means that are intermittently arranged in the conveying direction of the tubular sheet, in order from the one located upstream in the conveying direction.

2. The second joint portion has ridges and grooves extending in an extension direction of the second joint portion, and the ridges and grooves are alternately formed in a direction perpendicular to the extension direction, each of the plurality of heating and pressing means includes a pair of pressure-bonding bodies disposed opposite to each other, and is capable of heating and pressing the cylindrical sheet introduced between one and the other of the pair of pressure-bonding bodies; 2. The method for manufacturing a packaging body according to claim 1, wherein at least one of the plurality of heating and pressurizing means located at the most downstream in the conveying direction has uneven portions corresponding to the ridge portions and the groove portions at the contact portion with the tubular sheet in each of the pair of pressure-bonding bodies.

3. 3. The method for manufacturing a packaging body according to claim 1 or 2, wherein the desteaming section is 1) a section in which the bonding strength between the plurality of sheets is always lower than that of a section in the second joint where the desteaming section is not located, or 2) a section in which the bonding between the plurality of sheets constituting the desteaming section or its surrounding area is released by heating.

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