JP2000085798A - Tamperproof packaging bag and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recognize at a glance that a flap has been unsealed unjustly to prevent unjust unsealing. SOLUTION: The packaging bag 1 is formed of a front sheet 2, a rear sheet 3 and a flap 4 wherein contents are put from an opening 6 into the packaging bag 1. A rear face of the flap 4 is stuck to a surface of the rear sheet 3 by a first adhesive layer 7 and a second adhesive layer 8. The first adhesive layer 7 is provided in the vicinity of a tip of the flap 4, and the second adhesive layer 8 is provided in the vicinity of the opening 6. The first adhesive layer 7 comprises thermocompression-bonding-type adhesive which does not re-adhere once unsealed after adhesion, while the second adhesive layer 8 can be stuck again even if it has been peeled. Therefore even if the flap 4 is to be sealed again after it is unjustly unsealed, the tip of the flap 4 may roll up, whereby the bag which has been unjustly unsealed can be identified at a glance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging bag using a synthetic resin sheet or the like.

[0002]

2. Description of the Related Art In a conventional packaging bag, for example, a packaging bag for packaging printer paper used in a printer of a word processor or a personal computer is formed by folding one synthetic resin sheet and polymerizing a front sheet and a rear sheet. Generally, it is formed by heat-sealing the left and right edges. Such a packaging bag has a flap in which the end of the front sheet protrudes from the opening, and this flap is folded in the direction of the back sheet, so that the superposed surface of the flap and the back sheet is detachable double-sided adhesive tape. Etc. As described above, when the double-sided adhesive tape is used, even if the purchaser of the product once opens the flap of the packaging bag, the product can be resealed, which is convenient for storing the contents. A double-sided adhesive tape is often used for bonding the rear sheet.

[0003] However, the flap is sealed with the double-sided adhesive tape as described above when the product is displayed in a store and the contents are damaged due to unauthorized opening of the flap. Even so, by closing the flap again, the packaging bag can be sealed in the previous state. In this way, even if the packaging bag is opened improperly, it cannot be judged from the appearance whether the packaging bag has been opened improperly, so that the person who purchased the product or the store where the product was purchased is not damaged. May occur.

[0004]

SUMMARY OF THE INVENTION The present invention aims at improving a packaging bag. More specifically, in order to solve the above-mentioned inconvenience, it is possible to recognize at a glance that the flap has been opened when the flap is opened illegally. It is another object of the present invention to provide a packaging bag capable of preventing unauthorized opening and a method for manufacturing the same.

[0005]

In order to achieve the above object, a packaging bag according to the present invention is a rectangular packaging bag in which a front sheet and a rear sheet are superimposed and has an opening at one end edge,
The opening is provided with a flap extending from the front sheet, the flap is folded back toward the rear sheet, and the back surface of the flap and the surface of the rear sheet are superimposed, and the back surface of the flap and the surface of the rear sheet are provided. In a packaging bag provided with an adhesive layer in the width direction at the overlapping portion of the flap and sealing the flap with the adhesive layer, the adhesive layer is a first adhesive layer located near a front edge of the flap. And a second adhesive layer located in the vicinity of the opening, wherein the first adhesive layer is formed of an adhesive which does not adhere again once opened, and the second adhesive layer is opened once. Is also formed of an adhesive that can be adhered again.

According to the packaging bag of the present invention, the overlapped surface of the flap and the rear sheet is provided with the first adhesive layer which does not adhere again once opened, and the second adhesive layer which can be adhered again once opened. An adhesive layer is provided, and the flap is adhered to the rear sheet by the first and second adhesive layers. Therefore, when the packaging bag of the present invention is opened, the flap must be peeled off from the back sheet, so that the first and second adhesive layers are both peeled off. Here, when the packaging bag of the present invention is illegally opened and the flap is to be resealed thereafter, the flap and the rear sheet are bonded by the second adhesive layer, but the first bonding is performed. Since the agent layer does not adhere again once opened, the flap and the rear sheet are not adhered at the first adhesive layer portion. Since the first adhesive layer is provided near the front end of the flap, in this state, the front end of the flap is not fixed, but turns up and the like. Can be recognized. In addition, even when the purchaser or the salesperson touches the flap of the packaging bag that has been illegally opened, it can be immediately recognized that the packaging bag has been opened. As described above, according to the packaging bag of the present invention, even if the bag is opened improperly, the fact becomes apparent at a glance, so that the improper act can be immediately recognized, and thus the improper act can be prevented. Can contribute. On the other hand, even if the purchaser of the product opens the flap once, the flap can be sealed again by the second adhesive layer, which is convenient for storing the contents.

In the packaging bag of the present invention, both the first adhesive layer and the second adhesive layer may be provided on the surface of the back sheet, or may be provided on the back surface of the flap. Further, one of the first adhesive layer and the second adhesive layer may be provided on the back surface of the flap, and the other may be provided on the surface of the rear sheet.

The packaging bag of the present invention preferably has a cut line which can be cut between the first adhesive layer and the second adhesive layer of the flap. If the buyer purchases the flap and reseals it,
Although the tip portion of the flap is turned up, the tip portion of the flap provided with the first adhesive layer can be cut off by the cut line, so that the tip portion of the flap becomes obstructive during storage. Nothing.

[0009] The packaging bag of the present invention is preferably provided with a hook portion on one end edge of the packaging bag opposite to the opening so as to suspend the packaging bag. The packaging bag provided with the hanging portion is often displayed at the store by hanging the packaging bag with the hanging portion, but in the packaging bag of the present invention, if the flap is only the second adhesive layer, First, the first adhesive layer also adheres to the rear sheet. For this reason, the adhesive strength is higher than the conventional one,
Even if the weight of the contents is heavy, there is no possibility that the flap is opened by the weight of the contents and the contents are scattered.

The method of manufacturing a packaging bag according to the present invention is directed to a rectangular packaging bag having a front sheet and a rear sheet superimposed and having an opening at one end edge, wherein a flap extending from the front sheet is provided at the opening. A method of manufacturing a packaging bag, wherein the flap is folded back to the rear sheet side and the back surface of the flap and the surface of the rear sheet are polymerized and sealed, and the flap, the front sheet, the rear sheet, A printing process of performing gravure printing on the back surface of a long sheet having a plurality of sets in the longitudinal direction, and opening the sheet once at a position where the sheet is turned over and overlaps with the vicinity of the front end of the flap on the rear sheet surface. A first adhesive layer forming step of forming a first adhesive layer of a thermocompression bonding type that does not adhere again by gravure printing in the width direction of the sheet; A bag forming step of forming a bag by folding and polymerizing the back surface of the front sheet and the back surface of the back sheet so that the back surface of the back sheet is superposed, and forming a bag body by joining both side edges thereof, and near the opening on the back sheet surface A second adhesive layer forming step of forming in the width direction of the sheet a second adhesive layer capable of being adhered again even once opened at a position, and a contents storing step of storing contents in the formed bag. A flap folding step of folding the flap to the rear sheet side in a state where the contents are stored and superimposing on the rear sheet,
In a state where the flap is folded, the flap is pressed from the surface of the flap at the position where the first adhesive layer is provided, and the flap and the back sheet are thermocompressed, and the second adhesive layer is And a bonding step of pressing the flap from the surface of the flap at the provided position to bond the flap to the rear sheet.

In the method for manufacturing a packaging bag according to the present invention, printing is performed on the long sheet using gravure printing, and then the sheet is turned over to form the first adhesive layer by gravure printing. . Therefore, in the manufacturing method of the present invention, since printing of the sheet and formation of the first adhesive layer can both be performed by a gravure printing machine, it is necessary to provide a separate facility for applying the adhesive for forming the first adhesive layer. There is no. In particular,
When printing is performed by a gravure printing machine capable of performing double-sided printing in multicolor printing, the adhesive forming the first adhesive layer may be treated as one type of ink, and thus the formation of the first adhesive layer is easy. Becomes In addition, since the first adhesive layer uses a thermocompression bonding agent, the first adhesive layer provided on the back sheet can be thermocompression bonded from the surface of the flap. And the back sheet are easily bonded.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a packaging bag according to the present invention will be described with reference to FIGS. FIG. 1 is an explanatory view of a packaging bag showing an example of an embodiment of the present invention, FIG. 2 is an explanatory view showing details of a flap portion, FIG. 3 is an explanatory view showing a state in which the flap is once opened and sealed again, FIG.
FIG. 4 is an explanatory view showing a manufacturing process of the packaging bag of the present invention.

Referring to FIG. 1, a packaging bag 1 according to this embodiment is shown.
Is a bag for packaging printer paper used in a personal computer or the like, and is formed by a front sheet 2, a rear sheet 3, a flap 4, and a header 5. The packaging bag 1 is formed of a synthetic resin film in which a flap 4, a front sheet 2, a header 5, and a rear sheet 3 are sequentially arranged. Specifically, it is formed by performing printing showing the content of the product by gravure printing from the back surface of the oriented polypropylene film (OPP), and laminating a cast polypropylene film (CPP) on the printed surface.

The wrapping bag 1 has the front end of the rear sheet 3 aligned with the boundary between the flap 4 and the front sheet 2 and the center of the header 5 so that the back of the front sheet 2 and the back of the rear sheet 3 overlap. The portion is folded back and polymerized, the side edge of the sheet is blown, and the side edge of the sheet and the surface of the CPP film of the header 5 are thermally fused to form a bag. As a result, an opening 6 surrounded by the boundary between the front sheet 2 and the flap 4 and the front edge of the rear sheet 3 is formed. From this opening 6, the printer paper as the content is stored in the packaging bag 1 and The header 5 is formed. In addition, the header 5 is provided with a hanging hole 5 a which is a hanging portion for hanging the packaging bag 1.

Referring to FIG. 2, the back surface of flap 4 is the first
It is adhered to the surface of the back sheet 3 by the adhesive layer 7 and the second adhesive layer 8. The first adhesive layer 7 includes a flap 4
And the rear sheet 3 are overlapped with each other, and the flap 4
Is provided with a predetermined width in the width direction of the packaging bag 1 in the vicinity of the front end of the packaging bag 1. The second adhesive layer 8 includes the flap 4 and the rear sheet 3.
And the packaging bag 1 near the opening 6.
Are provided with a predetermined width in the width direction. The flap 4 is provided with a score line 9 between the first adhesive layer 7 and the second adhesive layer 8.

The first adhesive layer 7 is formed of a thermocompression-bonding adhesive which does not adhere again when it is opened after being adhered once. The adhesive is formed on the back sheet 3 by gravure printing, and the flap 4 is formed. Is folded back onto the back sheet 3 and polymerized, and then the back flap 4 is bonded to the back sheet 3 by thermocompression bonding from above the flap 4. The adhesive used for the first adhesive layer 7 was obtained by diluting a mixture of chlorinated polypropylene and ethylene-vinyl acetate copolymer resin with a solvent containing hydrocarbons and alcohols so that the solid content was 20 to 30%. Things. By setting the adhesive used for the first adhesive layer 7 to have such a composition, the first adhesive layer 7 can be formed using a gravure printing machine.
Can be formed.

In the present embodiment, the second adhesive layer 8 is formed of a double-sided pressure-sensitive adhesive tape. After the double-sided pressure-sensitive adhesive tape is attached to the back sheet 3 and the flap 4 is folded back on the back sheet 3 and polymerized, The flap 4 and the rear sheet 3 are pressed against the rear sheet 3 from above the flap 4.
And are glued. This double-sided pressure-sensitive adhesive tape is the same as those that are generally commercially available, and has adhesiveness on both sides,
Even if the flap 4 is once peeled off from the back sheet 3, both can be adhered again.

The cut line 9 is formed so that the flap 4 can be easily cut off by grasping both sides thereof with a finger in a state where the flap 4 is peeled off from the back sheet 3. on the other hand,
The score line 9 has such a strength that it is not cut off even when the flap 4 is opened with the end thereof held.
Therefore, when the purchaser of the product takes out the contents, the first adhesive layer 7 and the second adhesive layer 8 can be peeled off by holding the end of the flap 4 and opened.

When the packaging bag provided with the header 5 like the packaging bag 1 of the present embodiment is displayed at a store, a hook indicated by a broken line in FIG. 10 may be passed and suspended. When the packaging bag 1 is suspended in this manner, the weight of the printer paper as the content is applied to the flap 4. The packaging bag 1 of the present embodiment is different from the conventional packaging bag in that the flap 4 is not adhered to the back sheet 3 at one place, but instead has a first adhesive layer 7 and a second adhesive layer 8.
The bonding strength of the flap 4 is higher than that of the conventional packaging bag.

Further, since the packaging bag 1 of the present embodiment has the above configuration, when the packaging bag 1 is opened, it is necessary to peel the flap 4 from the back sheet 3. In this case, a person who intends to open the packaging bag 1 normally holds the left or right end of the leading edge of the flap 4 and flips the flap 4 open. By turning up the flap 4 in this way, first, the flap 4
The first adhesive layer 7 provided in the vicinity of the leading edge of the second adhesive layer is peeled off, and the second adhesive layer 8 provided in the vicinity of the opening 6 is subsequently peeled off. When the first adhesive layer 7 and the second adhesive layer 8 are all peeled off, the flap 4 is completely peeled off from the back sheet 3 and the opening 6 is opened.
The printer paper as the content can be taken out of the packaging bag 1.

When it is desired to take out the required number of printer papers and store the remaining papers in the packaging bag 1, the flap 4 is placed on the rear sheet 3 with the printer papers stored in the packaging bag 1 stored. What is necessary is just to polymerize. By polymerizing the flap 4 on the back sheet 3 in this way, the flap 4 is adhered to the back sheet 3 by the double-sided adhesive tape constituting the second adhesive layer 8, and the opening 6 is sealed. For this reason, the printer paper can be stored in a state protected by the packaging bag 1, and the contents do not jump out of the packaging bag 1 when carrying the packaging bag 1.

Next, a case where the packaging bag 1 of the present embodiment is opened by fraud will be described with reference to FIG. In a state where the product packaged by the packaging bag 1 of the present embodiment has been shipped from the manufacturer and displayed at the store,
The back sheet 3 and the flap 4 are adhered by a first adhesive layer 7 and a second adhesive layer 8. Further, in order to open the packaging bag 1 by fraudulent acts, it is necessary to peel off the first adhesive layer 7 and the second adhesive layer 8 and peel the flap 4 from the rear sheet 3 as described above. When the flap 4 is peeled off from the back sheet 3, a certain amount of force is applied to a portion having the flap 4 to separate the first adhesive layer 7 and the second adhesive layer 8, so that the flap 4 warps outward. As a result, the tip edge is also slightly wavy.

In this state, even if a person who commits wrongdoing tries to return the flap 4 to its original state and tries to adhere the flap 4 to the back sheet 3, the flap 4 is applied by the double-sided adhesive tape which is the second adhesive layer 8. Although the first adhesive layer 4 is adhered to the back sheet 3, once the first adhesive layer 7 is opened, the adhesive force disappears and the first adhesive layer 7 cannot be adhered again. As a result, as shown in FIG. 3, the tip of the flap 4 is rolled outward and turned up, and the tip edge of the flap 4 is also deformed in a wavy manner. Will be able to recognize. As a result, it can be seen that even a person who has committed an illegal act cannot conceal the illegal act, thereby contributing to prevention of the illegal act.

On the other hand, when the tip of the flap 4 is turned up, the purchaser of the product may feel that the flap 4 is annoying. In the present embodiment, the flap 4 including the portion of the first adhesive layer 7
Can be cut off by the cut line 9, so that the contents can be stored neatly in the packaging bag 1. In addition, even if the person who opened the packaging bag 1 illegally opens the front end of the flap 4 by the cut line 9 in the same manner, the first adhesive layer 7 remains on the surface of the back sheet 3. The fact that the line 9 has been cut off can also be recognized at a glance, which makes it easier to find fraudulent acts.

In the above embodiment, the packaging bag 1 provided with the cut line 9 has been described. However, the present invention is not limited to this.
The cut line 9 may not be provided. In the above embodiment, the packaging bag 1 including the header 5 has been described. However, the present invention is not limited to this, and the present invention may be applied to a packaging bag without a header. In the above embodiment, the first adhesive layer 7 and the second adhesive layer 8 are formed on the front surface of the back sheet 3. However, the present invention is not limited to this, and these adhesive layers are provided on the back surface of the flap 4. Alternatively, one of the first adhesive layer 7 and the second adhesive layer 8 may be provided on the back surface of the flap, and the other may be provided on the front surface of the rear sheet. The second adhesive layer 8 uses a double-sided pressure-sensitive adhesive tape in the above embodiment, but is not limited thereto, and may use an adhesive such as hot melt. Further, in the above embodiment, the sheet forming the packaging bag 1 is formed by laminating CPP on OPP, but the present invention is not limited to this, and a synthetic resin such as nylon or polyethylene which can be heat-sealed may be used.

Next, a method for manufacturing the packaging bag 1 of the present invention will be described with reference to FIG. First, the synthetic resin film forming the flap 4, the front sheet 2 and the rear sheet 3 of the packaging bag 1 is a roll-shaped sheet 21 as shown in FIG. Pull out and transport to the printing step (b). In the printing step (b),
Multicolor printing such as display of goods is performed on the back surface of the sheet 21 by the gravure printing machine 22a. Next, the sheet 21 is sent to the sheet reversing step (c), and the sheet 21 is turned upside down and transported to the next first adhesive layer forming step (d).

In the first adhesive layer forming step (d), an adhesive constituting the first adhesive layer which is adhered once and is not adhered again when peeled off is applied to the surface of the back sheet. The position is a position near the front end of the flap when the flap and the rear sheet are superimposed. The adhesive applied in the present embodiment is the same as the adhesive described above, and can be applied using the gravure printing machine 22b in the same manner as the gravure printing ink. The first adhesive layer forming steps (b to d) are performed using one gravure printing apparatus 22.

Next, the sheet 21 on which the gravure printing and the formation of the first adhesive layer have been completed is conveyed to the heater 23 and the drying step (e) is performed. In this drying step (e),
The ink printed on the sheet 21 and the first adhesive layer are dried. Next, the dried sheet 21 is conveyed to the laminating step (f), and a CP is printed on the back surface of the printed sheet 21.
P24 is laminated. Next, the laminated sheet 21 is formed into a bag in the bag forming step (g). Here, first, the sheet 21 is placed at the center 25 of the header 5.
After the front sheet 2 and the rear sheet 3 are overlapped, the front end and both side edges of the flap 4 of the sheet 21 are blown off by a heating press (not shown), and both side edges of the sheet 21 and the header 5 are cut. The CPP 24 laminated on the back surface of the substrate is thermally fused. Next, in the sheet processing step (h), the cut line 9 is formed by the cutter 26a at a position between the first adhesive layer 7 and the second adhesive layer 8 of the flap 4, and the header 5 is formed by the punch 26b. And a hanging hole 5a is formed in the center of the hole.

The sheet 21 formed in the bag is then
It is transported to the adhesive layer forming step (i). Note that, from the second adhesive layer forming step (i), the traveling direction is changed so that the sheet 21 proceeds in the width direction. In the second adhesive layer forming step, a second adhesive layer that can be adhered once even after being adhered and opened is formed on the surface of the back sheet 3. The position is a surface where the flap 4 and the back sheet 3 are superimposed and is a position near the opening 6 and is formed in the width direction of the back sheet 3. In the present embodiment, the second
The adhesive layer uses a double-sided adhesive tape, and the sheet 21
Double-sided adhesive tape supply roller 2 while advancing in the width direction
7, a double-sided adhesive tape is attached to the surface of the rear sheet 3.

Next, the contents 28 are stored in the sheet 21 formed into a bag in the contents storing step (j). In this embodiment, the contents 28 are printer paper. Then, the sheet 21 in which the contents are stored is conveyed to a flap folding step (k) in which the flap 4 is folded in the direction of the back sheet 3 and superimposed on the back sheet 3, and the flap 4 is folded.
And the back sheet 3 are polymerized.

As described above, in a state where the flap 4 is superimposed on the back sheet 3, the flap 4 is bonded to the back sheet 3 by the first adhesive layer 7 and the second adhesive layer 8 (l). Transported to In this flap bonding step (l), first, in order to bond the flap 4 and the back sheet 3 with the first adhesive layer 7, from the surface of the flap 4 where the first adhesive layer 7 is provided, The flap 4 is pressed against the rear sheet 3 by the heated press 29,
The first adhesive layer 7 is heated by the heat of the press 29 to bond the flap 4 and the rear sheet 3 together. At the same time,
From the surface of the flap 4 where the second adhesive layer 8 is provided, the flap 4 is pressed by an unheated press 30.
To the back sheet 3 to adhere. Thereby, the flap 4 is adhered to the back sheet 3 by the first adhesive layer 7 and the second adhesive layer 8, and the packaging of the contents 28 is completed.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a packaging bag showing an example of an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing details of a flap portion.

FIG. 3 is an explanatory view showing a state in which the flap is once opened and sealed again.

FIG. 4 is an explanatory view showing a manufacturing process of the packaging bag of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Packaging bag, 2 ... Front sheet, 3 ... Rear sheet, 4 ... Flap, 6 ... Opening, 7 ... 1st adhesive layer, 8 ... 2nd adhesive layer.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3E049 AA06 AB06 BA10 CA08 DB02 DB06 3E064 AA05 BA21 EA19 FA01 HM02 HN01 HN04 HP02 HQ10

Claims (7)

[Claims] 1. A rectangular packaging bag in which a front sheet and a rear sheet are superimposed and having an opening at one end edge, wherein the opening has a flap extending from the front sheet, and the flap is attached to the rear sheet. Side, the back surface of the flap and the surface of the back sheet are polymerized, and an adhesive layer is provided in a width direction at a portion where the back surface of the flap and the surface of the back sheet overlap, and the flap is formed by the adhesive layer. Wherein the adhesive layer comprises a first adhesive layer located near a leading edge of the flap, and a second adhesive layer located near the opening, and A packaging bag, wherein the adhesive layer is formed of an adhesive which does not adhere again once opened, and the second adhesive layer is formed of an adhesive which can be adhered again once opened. 2. The method according to claim 1, wherein the first adhesive layer and the second adhesive layer are
The packaging bag according to claim 1, wherein both are provided on the surface of the rear sheet. 3. The method according to claim 1, wherein the first adhesive layer and the second adhesive layer are
The packaging bag according to claim 1, wherein both are provided on the back surface of the flap. 4. The apparatus according to claim 1, wherein one of the first adhesive layer and the second adhesive layer is provided on a back surface of the flap, and the other is provided on a surface of the back sheet. Packaging bag. 5. The flap according to claim 1, further comprising a cut line cut in the width direction at a position between the first adhesive layer and the second adhesive layer. Or the packaging bag according to claim 1. 6. The packaging bag according to claim 1, further comprising a hook at one end edge of the packaging bag opposite to the opening to suspend the packaging bag. The packaging bag described. 7. A rectangular packaging bag in which a front sheet and a rear sheet are superimposed and having an opening at one end edge, wherein a flap extending from the front sheet is provided in the opening, and the flap is attached to the rear sheet. A method of manufacturing a packaging bag that seals by folding back to the side and polymerizing the back surface of the flap and the surface of the back sheet, wherein the flap, the front sheet, and the back sheet are 1
A printing step of performing gravure printing on the back surface of a long sheet having a plurality of sets in the longitudinal direction as a set, and once opened at a position where the sheet is inverted and overlapped with the vicinity of the front end of the flap on the rear sheet surface A first adhesive layer forming step of forming a first adhesive layer of a thermocompression bonding type which does not adhere again by gravure printing in the width direction of the sheet; and cutting the sheet for each set and the back surface of the front sheet. A bag forming step of forming a bag by folding back and polymerizing so that the back surface of the back sheet is polymerized and joining both side edges thereof.
A second adhesive layer forming step of forming, in the width direction of the sheet, a second adhesive layer that can be re-adhered once opened at a position near the opening on the surface of the rear sheet; A content storing step of storing an article, a flap folding step of folding the flap to the rear sheet side in a state where the content is stored, and superimposing the flap on the rear sheet, and the first flap in a state where the flap is folded. From the surface of the flap at the position where the second adhesive layer is provided, while pressing the flap from the surface of the flap at the position where the adhesive layer is provided and thermocompression bonding the flap and the back sheet. A method for manufacturing a packaging bag, comprising: a bonding step of pressing the flap to bond the flap to the rear sheet.