JPH11310246A - Breathable packaging bag and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suitably maintain freshness for articles requiring breathableness and to preserve satisfactorily external appearance while the articles are being housed by a method wherein filaments at places positioned on net welding lines are made flat ribbon parts and an approximately rectangular bag body is formed by welding the ribbon parts together. SOLUTION: For a bag body 1 wherein obverse and reverse net sheet parts 2 and 3 made of synthetic resin are arranged with an article housing chamber interposed in therebetween and net welding lines 6 are formed at edges on both sides thereof, parts facing the article housing chamber of the net sheet parts 2 and 3 are constructed of expandable/contractile meshes made up integrally in crossing of a number of monofilamentlike fiber 15. On the other hand, the filaments are formed in flat ribbon parts 17 at places positioned on the net welding lines 6 and welded together respectively at the obverse and reverse net sheet parts 2 and 3. Thereby, sufficient mechanical strength can be obtained at the welding line parts 6 and while sufficient breathableness can be ensured, the periphery can be maintained in a form resembling to its original shape of rectangle while the articles are housed therein.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a breathable packaging bag which can be sold over the counter in a state in which products which require particularly breathability, such as fresh fruits and vegetables, are stored, and a method for producing the same.

[0002]

2. Description of the Related Art Small vegetables such as green soybeans and okra, and small fruits such as kumquat (collectively referred to as fresh fruits and vegetables including such vegetables and fruits) are stored in packaging bags and sold over the counter. Therefore, it is necessary to guarantee air permeability in order to maintain freshness. For this reason, conventionally, there has been provided a tubular bag formed of a net tube having a stretchable mesh in which a large number of monofilament-shaped filaments are crossed and integrated.
That is, while cutting the net tube to a predetermined length, forming a tubular bag having a bottom by bundling and welding one end, storing fruit and vegetables in the tubular bag, and then stapling the paper header. This closes the opening of the tubular bag. However, since such a tubular bag is formed in a tubular shape, it swells in a radial direction in a state in which fruits and vegetables are stored, and the appearance for displaying products is not good.

[0003] By the way, the present applicant has proposed various types of packaging bags which can be sold over the counter in a state in which various small articles are stored. Such packaging bags include a front film made of a synthetic resin film and a front film made of a synthetic resin film. A substantially rectangular bag is constructed by fusing and welding the back film,
If necessary, a hanging header is provided at the top of the bag.
Accordingly, while the bag is swelled in both front and back directions in a state in which the product is stored, the periphery is distorted, but the periphery can be generally maintained in a shape close to the original rectangle, so that the appearance for displaying the product is not bad. However, when such a packaging bag is used as a packaging bag for fresh fruits and vegetables as described above, the stored fresh fruits and vegetables are hermetically sealed, poor in air permeability, and quickly deteriorated in freshness. That is, fresh fruits and vegetables maintain their freshness by respiration, and if the air permeability is impaired, they deteriorate early.

[0004]

Accordingly, the present inventors, when forming a packaging bag for fresh fruits and vegetables, constituted a net sheet portion made of synthetic resin on both sides of the bag body, and formed a net sheet portion on both front and back sides. If a substantially rectangular bag body is formed as a whole by welding, necessary and sufficient air permeability is guaranteed, and the appearance appearance in the product storage state as described above is good,
We have learned that we can provide an ideal packaging bag for fresh fruits and vegetables.

[0005] Then, when a material usable for the synthetic resin net sheet constituting such a packaging bag was searched, the following problems were further found. (1) Fresh fruits and vegetables as described above are relatively small bulk goods, but due to the packaging of fixed quantities, the packaging bag easily swells when the goods are stored from a flat state, ideally a net. It is desirable that the part expands and contracts. Therefore, if you use a synthetic resin net sheet that constitutes a stretchable mesh made by intersecting and integrating a large number of monofilament-shaped filaments, if both front and back net sheet parts are superimposed and fused and welded on both side edges It has been found that a bag that meets this requirement can be provided. However, when products are actually stored in a packaging bag made with such a net sheet, the fusing and welding parts of the front and back net sheets are easily peeled off, and it turns out that it is completely unusable. did. (2) Regarding the bag making method, as in the case of the conventional film bag, after the band-shaped net sheet is polymerized half-fold in the band width direction, the sheet is formed at predetermined intervals in the longitudinal direction of the half-folded net sheet. A technique for fusing and welding the front and back net sheet portions in the width direction is expected. According to this, bag production with high productivity can be performed. However, since the net sheet constituting the mesh formed of the monofilament-shaped filaments as described above is rich in elasticity and extremely low in shape retention, it is extremely difficult to fold the strip-shaped net sheet in half. In particular, since the mesh is easily deformed while expanding and contracting at the time of half-folding, the opposing edges of the folded net sheet are not aligned in line with each other, and it is extremely difficult to form a bag of a desired form. is there.

[0006]

SUMMARY OF THE INVENTION The present invention provides a breathable packaging bag which solves the above problems and a method for producing the same.

Therefore, the air-permeable packaging bag according to the present invention is configured as a first means, in that the both sides of the bag body 1 in which the front and back net sheets 2, 3 made of synthetic resin are disposed with the article storage chamber 4 interposed therebetween. Is a breathable packaging bag formed by forming net welding lines 6 for welding the two net sheet portions 2 and 3 to each other, wherein the net sheet portions 2 and 3 face the article storage chamber 4. At the portion, a stretchable mesh is formed by intersecting and integrating a large number of monofilament-shaped filaments 15, while at the portion located at the net welding wires 6, the ribbon portion 17 having a flat filament is formed. And the ribbon portion 17 is welded to each other between the front and back net sheet portions 2 and 3.

Further, the air-permeable packaging bag of the present invention is constituted as a second means in that both sides of the bag body 1 in which the front and back net sheets 2, 3 made of synthetic resin are disposed with the article storage chamber 4 interposed therebetween. , And a net welding wire 6 for welding the two net sheet portions 2 and 3 to each other is formed. A film piece 9 is superimposed on the opening edge 3a of the back net sheet portion 3 and is welded by the welding wire 10. In addition to being welded in the width direction of the opening edge 3a, the film piece 13
Is a breathable packaging bag formed by superimposing and welding together in the width direction of the opening edge 2a by a welding line 14, wherein the net sheet portions 2, 3 are formed of a large number of monofilaments at a portion facing the article storage chamber 4. Of the net welding lines 6, 6 and the welding lines 14, 1 of the front and back opening edges 2a, 3a.
In the portion located at 0, a ribbon portion 17 having a flat filament is formed, and the ribbon portion 17 is positioned at the net welding wires 6 and 6.
Are welded to each other in the front and back net sheet portions 2 and 3, and the ribbon portions 17 of the front and back opening edges 2a and 3a are positioned at the welding lines 14 and 10 of the front and back opening edges 2a and 3a. In that it is formed by welding. still,
The film piece welded 10 to the opening edge 3a of the back net sheet part 3 constitutes a sealing piece 9 extending upward from the opening edge 3a, and the film piece welded 14 to the opening edge 2a of the front net sheet part 2 It is preferable to form the receiving piece 13 and provide the adhesive layer 12 for bonding the sealing piece 9 and the receiving piece 13 to each other in a state where the sealing piece 9 is bent.

Further, the method for manufacturing a breathable packaging bag according to the present invention is constituted as means by: a net tube feeding step of feeding a net tube 18 made of synthetic resin having a mesh in a longitudinal direction; Cutting in the longitudinal direction to form a half-folded net sheet 22 having the half-folded front and back net sheet portions 2 and 3 in which the facing edges 2b and 3b are formed, and the half-folded net sheet 2
2, the film 24 fed from the roll 24a is overlapped with the facing edge 3b of the back net sheet portion 3, and the film 26 fed from the roll 26a is placed on the facing edge 2b of the front net sheet portion 2. A film feeding polymerization step for polymerization, a welding line 10 is formed on the facing edge 3b of the back net sheet portion 3 and the overlapping portion of the film 24, and the facing edge 2b of the front net sheet portion 2 and the film 2 are formed.
A welding wire 14 is formed in the overlapping portion of No. 6 and the welding wires 10 and 14 are formed.
A film welding wire forming step of welding the front and back net sheet portions 2 and 3 to the films 26 and 24, respectively;
A net welding line 6 formed by welding the front and back net sheet portions 2 and 3 in the width direction of the half-folded net sheet 22 at predetermined intervals in a longitudinal direction of the half-fold net sheet 22 is formed. A net welding wire forming step of welding the parts 2 and 3 to each other;
And a dividing step of dividing the pair of films 24 and 26 on the net welding line 6.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

[Embodiment of Breathable Packaging Bag] As shown in FIG. 1, the bag 1 has an article storage chamber 4 between a front net sheet 2 and a back net sheet 3 arranged on both sides. The two net sheet portions 2, 3 are located on both side edges of the bag body 1.
Are welded to each other.

In the illustrated example, the front and back net sheet portions 2, 3
Is a form in which one net sheet is folded along the bottom 7 of the bag body 1, and the front and back net sheet portions 2 and 3 are formed by two separate front and back net sheets, respectively. By providing welding lines similar to the net welding lines 6 on both side edges of the body 1 on the bottom 7 of the bag body 1, three sides except for the tops of the front and back net sheet portions 2 and 3 may be welded.

The front and back net sheet portions 2 in a folded state,
3 have opening edges 2a, 3a aligned in a straight line with each other, whereby the article storage chamber 4
Opening 8 is formed.

At the opening edge 3a of the back net sheet portion 3, a sealing piece 9 made of a synthetic resin film extending upward is provided, and the sealing piece 9 is opened in a state of being superposed on the outside of the back net sheet portion 3. A sealing piece welding wire 10 to be welded in the width direction of the edge 3a is formed. An adhesive layer 12 made of a pressure-sensitive adhesive covered with a release film 11 is provided near the free end of the sealing piece 9.

A receiving piece 13 made of a synthetic resin film is provided on the opening edge 2a of the front net sheet portion 2, and the receiving piece 13 is superposed on the outside of the opening edge 2a in the width direction of the opening edge 2a. Is formed with a welding wire 14 for welding.

Therefore, after releasing the release film 11,
The opening 8 can be closed via the sealing piece 9 by bending the sealing piece 9 and bonding the adhesive layer 12 to the outer surface of the receiving piece 13. At this time, instead of providing the adhesive layer 12 with the release film 11 on the sealing piece 9,
3 may be provided. In addition, a known chuck tape may be provided instead of the opening / closing fixing means using the adhesive layer 12.

As shown in FIG. 2 and FIG. 3, the front and back net sheet portions 2 and 3 are extendable and contractible by intersecting and integrating a large number of monofilament filaments 15 having a substantially circular or elliptical cross section. Construct a sheet with a mesh.

Therefore, the front and back net sheet portions 2 and 3 constitute a thread portion 16 having a substantially circular or elliptical cross section by the filament 15 at a portion facing the article storage room 4.
At portions located at the welding lines 6, 6, 10, and 14, a ribbon portion 17 having a flat filament 15 is formed. Such a ribbon portion 17 is positioned at the welding line and pressed by a heating body such as a hot plate until the filaments 15 constituting the front and back net sheet portions 2 and 3 are formed into a flat sheet-like ribbon shape. It is formed by continuing.

The ribbon portions 17 formed on the net welding lines 6 on both side edges of the bag body 1 are shown in FIGS. 2 and 3, and are positioned on the receiving welding lines 14 of the receiving pieces 13. The formed ribbon portion 17 is shown in FIG. Although the sealing piece welding wire 10 of the sealing piece 9 is not shown, a similar ribbon portion 17 is formed.

As shown in FIG. 3, the net welding lines 6, 6 formed on both side edges of the bag 1 are connected to the front and back net sheet portions 2, 3, respectively.
Are welded in a state in which the grid-like ribbon portions 17 in which the filaments 15 are formed flat are superimposed on each other, and are firmly connected not by linear welding but by planar welding. Such welding is achieved by crimping a heating body such as a hot plate from both the front and back surfaces with the net welding wires 6 interposed therebetween.

As shown in FIG. 2, the welding wire 14 formed on the receiving piece 13 is heated from the outside of the receiving piece 13 by heating the hot plate or the like from the outside of the receiving piece 13 with the receiving plate inserted inside the front net sheet portion 2. It is formed by pressing the body, whereby the receiving piece 13 is welded to the wire 15 located on the receiving piece welding wire 14 while compressing and deforming the wire 15 to form a flat ribbon portion 17. Then, a planar welding connection between the receiving piece 13 and the ribbon portion 17 is achieved. Although not shown, the sealing piece welding wire 10 of the sealing piece 9 is similarly heated from the outside of the sealing piece 9 by a heating element such as a hot plate with the receiving plate inserted inside the back net sheet portion 2. It is formed by pressure bonding, and achieves a planar welding connection between the sealing piece 9 and the ribbon portion 17.

[Embodiment of Bag Making Method] The material for forming the front and back net sheets 2 and 3 of the bag 1 is shown in FIG.
A net tube 18 as shown in FIG. As described above, the net tube 18 forms a stretchable mesh in which a large number of monofilament-shaped filaments 15 having a substantially circular or elliptical cross section are crossed and integrated, and as a flexible tube body. It is integrally molded.

As shown in FIG. 5, such a net tube 18 is wound in a longitudinal direction so as to form a roll 18a. Therefore, the net tube 18 constituting the roll 18a is tightened in a flat and flat form, thereby forming fold curves 19 and 20 substantially parallel to two opposing sides of the flat tube, as shown in FIG. It has been impatient. That is, the filament 15 constituting the tube is bent at the folding curves 19 and 20 to have a bending habit. The net tube 18 wound around the roll 18a
When the bending habits of the folding curves 19 and 20 are not sufficient, the paper is fed and then passed through a pair of sandwiching rollers to form the bending curves 19 and 20 having a sufficient bending habit. May be.

Therefore, the net tube 18 having the folding curves 19 and 20 and having a flat and flat shape is fed out from the roll 18a in the longitudinal direction (net tube feeding step).

The net tube 18 fed from the roll 18a is cut by a cutting means 21 having a cutting blade or a low-temperature fusing blade.
And the incision means 21 causes one of the fold curves 20
As shown in FIG. 4 (B), the front and back net sheet portions 2 extending in a half-fold state from the other fold curve 19 are cut along
3 is formed to form a half-folded net sheet 22 (incision step). Net tube 18 and half-folded net sheet 22
Because, if tension is applied in the transport state, the entire mesh will be easily deformed by easily deforming the mesh,
The sheet is sent to the intermittent drive rollers 23, 23 without tension without passing through a tension applying roll such as a step roll, and is intermittently transported. For this reason, the half-fold net sheet 22 cut by the cutting means 21 does not cause distortion,
As a result, the opposing edges 2b, 3b of the front and back net sheet portions 2, 3 cut along the folding curve 20 are aligned in a straight line with each other.

In order to provide the sealing piece 9, as shown in FIG. 5, a belt-like film 24 is unwound from a roll 24a.
When passing through the intermittent drive roller 23, the facing edge 3b of the back net sheet portion 3 of the half-folded net sheet 22
(A belt-like film feeding polymerization step). As shown in FIG. 4B, the belt-shaped film 24 includes the adhesive layer 12 covered with the release film 11.
The belt-shaped film 24 fed from the roll 24a is
The intermittent drive rollers 23, 2 without applying tension
3, but may be passed through a step roll group 25 for intermittent feeding as shown by a chain line in the figure.

In order to provide the receiving piece 13, as shown in FIG. 5, when the tape film 26 is unwound from the roll 26a and is passed through the intermittent driving roller 23,
It is superposed on the outside of the facing edge 2b of the front net sheet portion 2 of the half-fold net sheet 22 (tape film feeding polymerization step). It is preferable that the tape film 26 fed from the roll 26a be sent to the intermittent drive rollers 23 without applying tension, but as shown by a chain line in FIG. You may let it go.

Then, the half-folded net sheet 22 having passed through the intermittent drive roller 23 is intermittently transported from above and below with the tape film 26 and the belt-like film 24 superposed thereon, and is heated by a heating plate 28 such as a hot plate, an ultrasonic wave or a high frequency electrode. 29, the receiving piece welding wire 14 and the sealing piece 10 as described above are formed,
They are integrally joined (film welding wire forming step). At this time, as described above, the ribbon portion 17 is formed on the front and back net sheet portions 2 and 3 and is welded to the respective films 24 and 26 two-dimensionally.

Subsequently, the heating member 30 such as a hot plate or an ultrasonic or high-frequency electrode is used to separate the front and back net sheet portions 2 and 3 in the width direction of the half-folded net sheet 22 at predetermined intervals in the longitudinal direction of the half-folded net sheet 22. Is formed, and the front and back net sheet portions 2 and 3 are integrally joined (a net welding wire forming step). Thus, the ribbon portion 17 is formed on the front and back net sheet portions 2 and 3, and the ribbon portion 1 is formed.
As described above, the parts 7 and 17 can be welded to each other. At this time, the facing edges 2b and 3b of the front and back net sheet portions 2 and 3 are covered with the tape film 26 and the band-shaped film 24, respectively. Each of the films 26 and 24 is also formed with the net welding wire 6 at the same time and is welded and integrated with the front and back net sheet portions 2 and 3.

Thereafter, by the dividing means 31, the combined body of the half-folded net sheet 22, the band-shaped film 24 and the tape film 26 which is intermittently transferred is cut along the dividing line C located at the center of the width W of the net welding line 6. By dividing,
A bag 1 is obtained. The bag 1 is delivered to a predetermined position by a take-up conveyor 32. Although the cutting means 31 may use a cutting cutter, it is preferable to use a fusing blade.

[0031]

According to the breathable packaging bag of the present invention, it is possible to provide the bag body 1 having the front and back net sheet portions 2 and 3 on both sides sandwiching the article storage room 4, so that the bag 1 is particularly breathable such as fresh fruits and vegetables. The freshness of the product requiring the property can be preferably maintained, and in the product storage state, the bag body 1 swells on both the front and back surfaces and does not swell in the radial direction as in the conventional net tubular bag, and the periphery thereof is somewhat increased. Although the warp is distorted, the entire periphery can be maintained in a form close to the original rectangle, so that the appearance for displaying the goods is good.

In particular, since the front and back net sheets 2 and 3 form a stretchable mesh in which a large number of monofilament filaments 15 are crossed and integrated at a portion facing the article storage room 4, air permeability and air permeability are improved. At the same time, the product has good fit. In this regard, such a net material is conventionally considered to be unable to be firmly welded, but according to the present invention, at the portion located at the net welded wire 6,6, Since the strip 15 is deformed from a monofilament to form a flat ribbon portion 17, and the ribbon portions 17, 17 of the front and back net sheets 2, 3 are welded to each other in a planar manner, sufficient mechanical strength is obtained. Has a remarkable effect in that a practical breathable packaging bag can be provided.

Further, according to the breathable packaging bag of the present invention, the film pieces 13 and 9 are superimposed on the opening edges 2a and 3a of the front and back net sheet portions 2 and 3, respectively, and the welding wires 14 and 10 are formed.
, A pair of film pieces 1
The opening 8 can be suitably sealed via the openings 3 and 9. When such film pieces 13 and 9 are provided, the welding lines 14 and 10 of the front and back opening edges 2a and 3a are also provided.
Monofilament filament 15
Is formed, and the front and back opening edges 2a,
Since the ribbon portion 3a is welded to the respective film pieces 13 and 9 in a planar manner, sufficient mechanical strength is satisfied.

At this time, the opening edge 3a of the back net sheet portion 3
A sealing piece 9 extending upward from the opening edge 3a is constituted by the film piece welded 10 to the opening piece 3; a receiving piece 13 is constituted by a film piece welded 14 to the opening edge 2a of the front net sheet portion 2; If the adhesive layer 12 for bonding the sealing piece 9 and the receiving piece 13 to each other in a state in which the sealing piece 9 is bent is provided,
It is possible to provide a bag in which the opening 8 can be freely opened and closed.

When such a bag 1 is made into a bag, if the band-shaped net sheet is half-folded in the band width direction like a conventional film bag, the net sheet can be easily formed at the time of folding. Deformation does not align the opposing edges of the folded net sheet with each other in a straight line, and has a problem that it is difficult to form a desired bag body. Instead of using a band-shaped net sheet, a tube-shaped net tube 18 is used, and the net tube 18 is fed out in the longitudinal direction (net tube feeding step). A half-folded net sheet 22 including the front and back net sheet portions 2 and 3 in a half-fold state in which the half-folded net sheets 2b and 3b are formed (cutting step). Polymerizing each film 24, 26 opposite edge 3b, to 2b pairs (film feeding polymerization step), the weld lines 10 formed in each of the overlapping portions,
14, the films 24, 26 are applied to the facing edges 3b, 2b.
(A welding wire forming step), the resulting half-folded net sheet 22 is not distorted, and the cut back and front net sheet portions 2, 3 are provided with the films 24, 26. The facing edges 3b, 2b are aligned in a straight line with each other and aligned, and the bag body 1 is completed through various steps including a net welding line forming step and a dividing step thereafter.
However, it has a remarkable effect of high quality and high accuracy.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a breathable packaging bag of the present invention, wherein (A) is a front view and (B) is a longitudinal sectional view.

FIG. 2 is an enlarged front view showing a part of a breathable packaging bag.

FIG. 3 is an enlarged perspective view showing a part of a breathable packaging bag.

FIG. 4 shows an embodiment of the method for producing a breathable packaging bag of the present invention, wherein (A) is a perspective view showing a net tube,
(B) is a perspective view showing a state in which the strip film and the tape film are overlapped after cutting the net tube.

FIG. 5 is an explanatory view showing one example of a bag making machine for carrying out the method for producing a breathable packaging bag of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bag body 2 Front net sheet part 3 Back net sheet part 2a, 3a Opening edge 2b, 3b Opposing edge 4 Article storage room 6 Net welding line 8 Opening 9 Sealing piece 10 Sealing piece welding wire 13 Receiving piece 14 Receiving piece welding Wire 15 Monofilament-shaped filament 16 Thread 17 Ribbon 18 Net tube 19, 20 Fold curve 21 Incision means 22 Half-fold net sheet 28, 29, 30 Heating body 31 Breaking means

Claims (4)

[Claims] 1. Net welding for welding both net sheets 2, 3 to each other at both side edges of a bag 1 in which front and back net sheets 2, 3 made of synthetic resin are arranged with an article storage chamber 4 interposed therebetween. It is a breathable wrapping bag formed by forming the wires 6, 6 and a plurality of monofilament-shaped filaments 15 are crossed and integrated at a portion where the net sheet portions 2, 3 face the article storage room 4. While forming a stretchable mesh, a ribbon portion 17 having a flat line is formed at a portion located at the net welding lines 6, 6, and the ribbon portion 17 is formed between the front and back net sheet portions 2, 3. A breathable packaging bag characterized by being welded. 2. A net welding for welding the two net sheet portions 2 and 3 to each other on both sides of the bag 1 on which the front and back net sheet portions 2 and 3 made of synthetic resin are disposed with the article storage chamber 4 interposed therebetween. The film pieces 9 are superposed on the opening edge 3a of the back net sheet portion 3 and welded in the width direction of the opening edge 3a by the welding wire 10, and the opening of the front net sheet portion 2 is formed. A gas-permeable packaging bag in which a film piece 13 is superimposed on an edge 2a and welded in the width direction of the opening edge 2a by a welding line 14, where the net sheet portions 2, 3 face the article storage chamber 4. In this example, a plurality of monofilament-shaped filaments 15 intersect to form a stretchable mesh, which is integrated with the net welding wires 6, 6 and the welding wires 14, 10 of the front and back opening edges 2a, 3a. Striations at the site Rights and to the formation of the ribbon portion 17, located in the net weld lines 6,6 as well as welding in mutual sides net seat 2 the ribbon section 17, the front and rear opening edge 2a, 3a of the weld line 1
Ribbon portions 1 of front and back opening edges 2a, 3a located at 4, 10
7. A breathable packaging bag, wherein 7 is welded to each of the film pieces 13 and 9. 3. A film piece welded to the opening edge 3a of the back net sheet portion 3 constitutes a sealing piece 9 extending upward from the opening edge 3a, and is welded 14 to the opening edge 2a of the front net sheet portion 2. The film piece thus formed constitutes a receiving piece (13), and an adhesive layer (12) for bonding the sealing piece (9) and the receiving piece (13) to each other in a state where the sealing piece (9) is bent is provided. A breathable packaging bag according to claim 1. 4. A net tube feeding step for feeding a net tube 18 made of synthetic resin having a mesh in the longitudinal direction, and a half in which the facing ends 2b, 3b are formed by cutting the net tube 18 in the longitudinal direction. A cutting step of forming a half-folded net sheet 22 including the front and back net sheet portions 2 and 3 in a folded state; and a back net sheet portion 3 in the half-folded net sheet 22
A film feeding polymerization step of polymerizing the film 24 fed from the roll 24a on the facing edge 3b of the front net sheet portion 2 and polymerizing the film 24 fed from the roll 24a on the facing edge 3b of the front net sheet portion 2. The opposite edge 3b of the back net sheet portion 3 and the film 24
The welding wire 10 is formed in the overlapping portion of the front net sheet portion 2 and the welding wire 14 is formed in the overlapping portion of the film 26 and the overlapping portion of the film 26, and the front and back net sheet portions 2, 3 are formed in the welding wires 10, 14. And a net welding line in which the front and back net sheet portions 2 and 3 are welded in the width direction of the half-folded net sheet 22 at predetermined intervals in the longitudinal direction of the half-folded net sheet 22. 6, a net welding wire forming step of welding the front and back net sheet portions 2 and 3 to each other at the portion of the net welding wire 6, a front and back net sheet portion 2 and 3, and the pair of films 2
And a dividing step of dividing the nets 4 and 26 on the net welding wire 6.