Packaging bags

Abstract

To provide a packaging bag which is easily manufactured and easily recycled.SOLUTION: The packaging bag is formed by thermally bonding peripheral edges of a first sheet 21, a second sheet 22, a third sheet 23 and a fourth sheet 24 which are laminated. The first sheet 21, the second sheet 22, the third sheet 23 and the fourth sheet 24 are made of polyolefin-based resins, and at least one of the opposing surfaces of the first sheet 21 and the third sheet 23 and at least one of the opposing surfaces of the second sheet 22 and the fourth sheet 24 are subjected to corona treatment.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a packaging bag. [Background technology]

[0002] Semiconductor products, silicon wafers, magnetic disks, and other such products are susceptible to the adhesion of foreign matter such as dirt, dust, and dirt. Therefore, these products are processed in clean rooms. These products are often used in clean rooms. Therefore, packaging bags with special structures are used to prevent foreign matter from adhering to the products during distribution and to prevent foreign matter from entering the clean room (see, for example, Patent Document 1).

[0003] Packaging bags used for such purposes have a release film disposed on the surface of the packaging bag. An item is placed inside the packaging bag, which is then sealed and distributed. During distribution, the packaging bag may become contaminated with foreign matter. Before transporting the item into a clean room, the release sheet contaminated by foreign matter is peeled off, and the packaging bag with a clean interior is transported into the clean room. This prevents foreign matter from entering the clean room. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5151555 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the packaging bag of Patent Document 1 uses a sheet in which a base layer made of a biaxially oriented plastic film and a sealant layer made of a polyolefin resin are laminated, which requires time and effort to manufacture the sheet. In addition, since the bag is made of multiple different materials, it is difficult to recycle.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a packaging bag that is easy to manufacture and to recycle. [Means for solving the problem]

[0007] To achieve the above object, the packaging bag of the present invention comprises four stacked sheets whose peripheral edges are heat-sealed. The packaging bag has a first sheet and a second sheet arranged facing each other, a third sheet arranged on the outside of the first sheet, and a fourth sheet arranged on the outside of the second sheet. The first, second, third, and fourth sheets are formed of a polyolefin resin. Corona treatment is applied to at least one of the opposing surfaces of the first and third sheets and at least one of the opposing surfaces of the second and fourth sheets.

[0008] In the packaging bag having the above configuration, corona treatment is applied to both of the opposing surfaces of the first sheet and the third sheet and to both of the opposing surfaces of the second sheet and the fourth sheet.

[0009] The packaging bag having the above-described configuration has an unbonded portion that is not thermally bonded on the outer side of the thermally bonded portion.

[0010] In the packaging bag having the above configuration, an opening start portion is provided in the heat-sealed portion of the first sheet and the second sheet.

[0011] In the packaging bag having the above configuration, the third sheet and the fourth sheet have a higher heat resistance temperature than the first sheet and the second sheet.

[0012] In the packaging bag having the above configuration, the first sheet, the second sheet, the third sheet, and the fourth sheet are all made of polyethylene.

[0013] In the packaging bag having the above configuration, the first sheet, the second sheet, the third sheet, and the fourth sheet are all made of polypropylene.

[0014] In the packaging bag having the above configuration, the first sheet and the second sheet are made of unstretched polypropylene, and the third sheet and the fourth sheet are made of stretched polypropylene.

[0015] In order to achieve the above object, the present invention provides a packaging bag manufacturing apparatus that stacks a first sheet and a second sheet arranged opposite each other, a third sheet arranged outside the first sheet, and a fourth sheet arranged outside the second sheet, and thermally seals the peripheral edges of the four stacked sheets. The packaging bag manufacturing apparatus includes a first roll around which the first sheet is wound in a roll shape, a second roll around which the second sheet is wound in a roll shape, a third roll around which the third sheet is wound in a roll shape, and a fourth roll around which the fourth sheet is wound in a roll shape, and a thermal sealing unit that simultaneously heats and pressurizes the peripheral edges of the four stacked sheets pulled out from each roll. The third roll, the first roll, the second roll, and the fourth roll are arranged in this order. The third sheet is wound around the third roll so that the surface facing the first sheet is a corona-treated surface. The first sheet is wound around the first roll so that the surface facing the third sheet is a corona-treated surface. The second sheet is wound around the second roll so that the surface facing the fourth sheet is a corona-treated surface, and the fourth sheet is wound around the fourth roll so that the surface facing the second sheet is a corona-treated surface. [Effects of the Invention]

[0016] According to the packaging bag of the present invention, it is possible to provide a packaging bag that is easy to manufacture and easy to recycle. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a front view of an embodiment of a packaging bag according to the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view of the packaging bag shown in FIG. [Figure 3] FIG. 10 is a front view showing a state in which the exterior part is being removed from the packaging bag. [Figure 4] FIG. 2 is a schematic layout diagram of a packaging bag manufacturing device. [Figure 5] FIG. 10 is a schematic layout diagram of another example of a packaging bag manufacturing apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0018] Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front view of one embodiment of a packaging bag according to the present invention. FIG. 2 is a schematic cross-sectional view of the packaging bag shown in FIG. 1. FIG. 3 is a front view showing a state in which an exterior part 102 has been removed from the packaging bag. As shown in FIG. 1, the packaging bag 100 is a rectangular bag body, and is a four-sided sealed pouch with four sides thermally sealed. In FIG. 1, the thermally sealed part 11 is hatched with a traffic lane. Also, the article Wh is indicated by a dashed line. The packaging bag 100 contains articles that require prevention of contamination by foreign matter such as dust and dirt, such as semiconductor products, silicon wafers, and magnetic disks. The packaging bag 100 is used to transport these articles.

[0019] The packaging bag 100 is formed by stacking and thermally bonding four sheets made of resin. The packaging bag 100 has a first sheet 21 and a second sheet 22 arranged opposite each other, a third sheet 23 arranged on the opposite side of the second sheet 22 with the first sheet 21 in between, and a fourth sheet 24 arranged on the opposite side of the first sheet 21 with the second sheet 22 in between. The packaging bag 100 is stacked in the order of the third sheet 23, first sheet 21, second sheet 22, and fourth sheet 24.

[0020] The packaging bag 100 has a configuration including a bag body 101 having a storage space 10 surrounded by a first sheet 21 and a second sheet 22, and an exterior part 102 made up of a third sheet 23 and a fourth sheet 24.

[0021] The packaging bag 100 has a storage space 10, a thermally bonded portion 11, a notch portion 12, and a turning-over start portion 13. The thermally bonded portion 11 is formed by thermally bonding adjacent sheets together. Details of the thermal bonding will be described later. The storage space 10 is an area surrounded by the thermally bonded portion 11 between the first sheet 21 and the second sheet 22.

[0022] In the packaging bag 100 according to this embodiment, the first sheet 21, the second sheet 22, the third sheet 23, and the fourth sheet 24 all have the same configuration. Therefore, the first sheet 21, the second sheet 22, the third sheet 23, and the fourth sheet 24 are formed from a polyolefin-based resin. By forming each sheet from a polyolefin-based resin, adjacent sheets can be thermally bonded together by applying heat and pressure.

[0023] 2, the outer surface of the first sheet 21, which faces the third sheet 23, is a corona-treated treated surface 211. Similarly, the outer surface of the second sheet 22, which faces the fourth sheet 24, is a corona-treated treated surface 221.

[0024] The inner surface of the third sheet 23, which faces the first sheet 21, is a corona-treated treated surface 231. The inner surface of the fourth sheet 24, which faces the second sheet 22, is a corona-treated treated surface 241.

[0025] 2, the inner surface 212 of the first sheet 21 and the inner surface 222 of the second sheet 22, which have not been subjected to corona treatment, face each other in the stacking direction. Also, the treated surface 211 of the first sheet 21 and the treated surface 231 of the third sheet 23, which have been subjected to corona treatment, face each other, and the treated surface 221 of the second sheet 22 and the treated surface 241 of the fourth sheet 24 face each other.

[0026] Then, the third sheet 23, the first sheet 21, the second sheet 22, and the fourth sheet 24 are stacked in this order, and then the peripheral portions are heated and pressurized from the outside of the third sheet 23 and the outside of the fourth sheet 24. As described above, the first sheet 21, the second sheet 22, the third sheet 23, and the fourth sheet 24 are made of a polyolefin resin. Therefore, when the third sheet 23, the first sheet 21, the second sheet 22, and the fourth sheet 24 are heated and pressurized, they are thermally bonded to one another, and thermally bonded portions 11 are formed.

[0027] In the packaging bag 100, the four sides are heat-sealed with the article Wh placed between the first sheet 21 and the second sheet 22. As a result, the article Wh is accommodated in the accommodation space 10, and the accommodation space 10 is sealed.

[0028] The corona-treated surface has the property that the adhesive strength of the thermally bonded portion 11 is lower than that of the untreated surface. When the four sheets are stacked, the opposing surfaces of the third sheet 23 and the first sheet 21 are both corona-treated. In addition, the opposing surfaces of the second sheet 22 and the fourth sheet 24 are also corona-treated. Therefore, the second adhesive portion 112 between the first sheet 21 and the third sheet 23 and the second adhesive portion 112 between the second sheet 22 and the fourth sheet 24 have lower adhesive strength than the first adhesive portion 111 between the first sheet 21 and the second sheet 22. In other words, the third sheet 23 and the fourth sheet 24 can be easily separated from the bag body 101 (see FIG. 3).

[0029] 1, that is, on the outside of the heat-sealed portion 11 when viewed from the stacking direction. At the turning-start portion 13, the third sheet 23 and the first sheet 21 are not bonded together. Also, the fourth sheet 24 and the second sheet 22 are not bonded together. In the packaging bag 100 according to this embodiment, the first sheet 21 and the second sheet 22 are not bonded together either.

[0030] With this configuration, the third sheet 23 and the first sheet 21 can be individually grasped at the turning start portion 13. In this state, the third sheet 23 is moved in the stacking direction away from the first sheet 21 and the second sheet 22. As described above, the second adhesive portion 112 has a lower adhesive strength than the first adhesive portion 111, and therefore the third sheet 23 can be peeled off from the first sheet 21 while suppressing peeling between the first sheet 21 and the second sheet 22. Similarly, the fourth sheet 24 and the second sheet 22 can be individually grasped at the turning start portion 13. This allows the fourth sheet 24 to be peeled off from the second sheet 22.

[0031] In the packaging bag 100 of this embodiment, the outer surface of the first sheet 21 is the treated surface 211, and the inner surface of the third sheet 23 is the treated surface 231. However, this is not limited to this, and it is sufficient that at least one of them has been subjected to corona treatment. In other words, it is sufficient that either the outer surface of the first sheet 21 or the inner surface of the third sheet 23 has been subjected to corona treatment. Similarly, it is sufficient that either the outer surface of the second sheet 22 or the inner surface of the fourth sheet 24 has been subjected to corona treatment.

[0032] The notch portion 12 is provided, for example, on the side opposite the turning-over start portion 13 of the thermally sealed portion 11. That is, in the packaging bag 100 according to this embodiment, the notch portion 12 is provided on the left and right sides of the upper portion of the thermally sealed portion 11. The notch portion 12 is a V-shaped cutout. The shape of the notch portion 12 is not limited to a V-shape, and it may be an I-shape, a U-shape, or a home plate shape. The packaging bag 100 is opened by being torn from the notch portion 12. That is, the notch portion 12 is an opening start portion. The notch portion 12 may be formed in all sheets, or, in the case where the bag body 101 is opened after peeling off the exterior portion 102, the notch portion 12 may be formed only in the first sheet 21 and the second sheet 22.

[0033] Next, a manufacturing apparatus and method for the packaging bag 100 will be described with reference to the drawings. Fig. 4 is a schematic layout diagram of a packaging bag manufacturing apparatus 300. The packaging bag manufacturing apparatus 300 has a first roll 31, a second roll 32, a third roll 33, a fourth roll 34, a table 35, a cutter 36, and a heat sealing unit 37.

[0034] In the packaging bag manufacturing apparatus 300, a third roll 33, a first roll 31, a second roll 32, and a fourth roll 34 are arranged in line from top to bottom. The first roll 31 has a configuration in which the first sheet 21 is wound around a shaft 311. In the first roll 31, the first sheet 21 is wound around the shaft 311 so that the treatment surface 211 faces outward. In the first roll 31, the first sheet 21 is pulled out from above the shaft 311 toward the table 35.

[0035] The second roll 32 has a configuration in which the second sheet 22 is wound around a shaft 321. In the second roll 32, the second sheet 22 is wound around the shaft 321 so that the processing surface 221 faces inward. The second roll 32 is disposed below the first roll 31, and the second sheet 22 is pulled out from above the shaft 321 toward the table 35.

[0036] The third roll 33 has a configuration in which the third sheet 23 is wound around a shaft 331. In the third roll 33, the third sheet 23 is wound around the shaft 331 so that the processing surface 231 faces inward. The third roll 33 is disposed above the first roll 31, and the third sheet 23 is pulled out from above the shaft 331 toward the table 35.

[0037] The fourth roll 34 has a configuration in which the fourth sheet 24 is wound around a shaft 341. In the fourth roll 34, the fourth sheet 24 is wound around the shaft 341 so that the processing surface 241 faces outward. The fourth roll 34 is disposed below the second roll 32, and the fourth sheet 24 is pulled from above the shaft 341 toward the table 35.

[0038] The sheets fed from each roll are guided to table 35 by rollers 301. The fourth sheet 24, second sheet 22, first sheet 21, and third sheet 23 are stacked on top of each other in this order on table 35. Each sheet is placed on table 35 so that its top and bottom surfaces are the same as when it was pulled out from its corresponding roll.

[0039] That is, the first sheet 21 has a treated surface 211 as its upper surface, and the second sheet 22 has a treated surface 221 as its lower surface. Furthermore, the third sheet 23 has a treated surface 231 as its lower surface, and the fourth sheet 24 has a treated surface 241 as its upper surface. As a result, the first sheet 21 and the second sheet 22 are arranged with their untreated surfaces, which have not been subjected to corona treatment, facing each other. The first sheet 21 and the third sheet 23, and the second sheet 22 and the fourth sheet 24, are arranged with their treated surfaces facing each other.

[0040] The cutter 36 cuts the first sheet 21, the second sheet 22, the third sheet 23, and the fourth sheet 24. In the packaging bag manufacturing apparatus 300, after the four sheets are stacked, all of the sheets are cut together. However, the configuration of the cutter 36 is not limited to this. For example, the cutter may be configured to cut the sheets individually as they are pulled out from each roll. The cutter can be configured in a wide variety of ways to accurately and reliably cut the sheets.

[0041] The table 35 is a platform on which the sheets are placed. The table 35 has, for example, positioning portions 351 that come into contact with the sides of the first sheet 21, the second sheet 22, the third sheet 23, and the fourth sheet 24 to position them. Note that if the sheet positioning can be achieved by another method, the positioning portions 351 may be omitted. When all the sheets are placed on the table 35, the article Wh is placed between the first sheet 21 and the second sheet 22.

[0042] The heat-sealing section 37 applies heat and pressure from the outside of the positioned sheets in the stacking direction, in other words, from the outside of the third sheet 23 and the fourth sheet 24, to form the heat-sealed section 11. The part of the heat-sealing section 37 that presses the sheets from below is placed on the table 35, and the part that presses the sheets from above is configured to be able to approach and move away from the table 35.

[0043] In the packaging bag manufacturing apparatus 300, the article Wh is placed between the first sheet 21 and the second sheet 22 before being heat-sealed by the heat-sealing section 37. Then, in this state, the four sides are heat-sealed to seal the article Wh in the storage space 10. Then, in the packaging bag manufacturing apparatus 300, a cutter 36 is used to form a notch 12 in the heat-sealed section 11.

[0044] The packaging bag manufacturing apparatus 300 is operated in a clean room to prevent foreign matter such as dirt, dust, and dirt from adhering to the item Wh. Even when the manufactured packaging bag 100 is taken out of the clean room, the item Wh does not come into contact with the outside air. This prevents foreign matter such as dirt, dust, and dirt floating in the outside air from adhering to the item Wh.

[0045] After production, the article Wh is stored and sealed inside the storage space 10 of the packaging bag 100 in a clean room. The article Wh is used, for example, by being incorporated inside a device. The manufacturing process for incorporating the article Wh into the device is also often carried out in a clean room to prevent adhesion of foreign matter.

[0046] The packaging bag 100 containing the item Wh is then removed from the clean room used for manufacturing and transported to a clean room used for manufacturing the equipment. That is, the outer surface of the exterior part 102 of the packaging bag 100 comes into contact with the outside air when transported between different clean rooms. That is, during transport, foreign matter such as dirt, dust, and dirt adheres to the outer surface of the exterior part 102 of the packaging bag 100. Furthermore, because the outer surfaces of the first sheet 21 and the second sheet 22 are covered by the third sheet 23 and the fourth sheet 24, the adhesion of foreign matter such as dirt, dust, and dirt is prevented. That is, the outer surfaces of the first sheet 21 and the second sheet 22 are not contaminated with foreign matter such as dirt, dust, and dirt; in other words, they are in a clean state.

[0047] When the packaging bag 100 is carried into a clean room for manufacturing equipment, the exterior portion 102, i.e., the third sheet 23 and the fourth sheet 24, are peeled off. The packaging bag 100 has the turning-over start portion 13, so that the third sheet 23 and the fourth sheet 24 can be pinched, respectively. Then, the third sheet 23 and the fourth sheet 24 are pulled outward.

[0048] In the packaging bag 100, the second adhesive portion 112 between the third sheet 23 and the first sheet 21 and the second adhesive portion 112 between the fourth sheet 24 and the second sheet 22 have weaker adhesive strength than the first adhesive portion 111 between the first sheet 21 and the second sheet 22. As a result, the third sheet 23 and the fourth sheet 24 can be easily peeled off from the bag main body 101 without damaging the bag main body 101, i.e., without peeling off the first adhesive portion 111. In other words, in the packaging bag 100, the exterior portion 102 contaminated with foreign matter such as dirt, dust, and dirt can be separated from the bag main body 101. This allows the first sheet 21 and the second sheet 22, i.e., the bag main body 101, whose outer surfaces are kept clean, to be exposed.

[0049] When using the packaging bag 100, the third sheet 23 and the fourth sheet 24 are peeled off immediately before the bag is carried into a clean room for manufacturing equipment. This allows only the bag body 101 formed from the first sheet 21 and the second sheet 22, which is not contaminated with foreign matter such as dirt, dust, or dirt, to be carried into the clean room for manufacturing equipment. This prevents foreign matter such as dirt, dust, or dirt from adhering to the item Wh and also prevents foreign matter from entering the clean room. Then, in the clean room for manufacturing equipment, the bag body 101 is opened by tearing it starting from the notch portion 12, and the item Wh stored inside the storage space 10 is removed.

[0050] By using the packaging bag 100 described above, adhesion of foreign matter such as dirt, dust, and dirt to the item Wh can be prevented even when the item Wh manufactured in the clean room is removed from the clean room for transport to another clean room. The intrusion of foreign matter such as dirt, dust, and dirt into the clean room can also be prevented. Furthermore, the packaging bag 100 uses a polyolefin-based resin for the first sheet 21, the second sheet 22, the third sheet 23, and the fourth sheet 24, which allows for bonding with a single heat bonding. This makes it easy to recycle the packaging bag 100. The sheet manufacturing process can be simplified compared to when using a sheet formed by laminating multiple layers.

[0051] As described above, the packaging bag 100 is opened by tearing the bag body 101 after the third sheet 23 and the fourth sheet 24 have been peeled off. Therefore, the notch portion 12 may be formed only in the first sheet 21 and the second sheet 22. However, in the packaging bag manufacturing apparatus 300 according to the present embodiment, the notch portion 12 is formed after the packaging bag 100 is manufactured. Therefore, the notch portion 12 is formed in all of the first sheet 21, the second sheet 22, the third sheet 23, and the fourth sheet 24.

[0052] The packaging bag manufacturing apparatus 300 employs a method of cutting the sheets with the cutter 36, arranging them, and thermally bonding them to manufacture the packaging bag 100, but this is not limiting. For example, the cutter 36 may be used to cut the sheets after forming thermally bonded sections 11 on four sides. When the stacked sheets are cut with the cutter 36, the cut is made on the thermally bonded sections 11 on three sides. Furthermore, the cut is made on the outer side of the thermally bonded sections 11 on the remaining side. In this manner, the turning start section 13 can be formed.

[0053] By doing so, it is not necessary to accurately position the table 35. Therefore, the configuration of the packaging bag manufacturing apparatus 300 can be simplified.

[0054] Furthermore, when the stacked sheets are heat-sealed, three of the four heat-sealed portions 11 or two opposing sides may be bonded in advance, and the items Wh may be placed in the bag body 101 via the unbonded portions. In this way, the items Wh are not placed during the initial heat-sealing, and therefore, displacement of the sheets due to the placement of the items Wh can be suppressed. Furthermore, by leaving the two opposing sides unbonded, for example, it is possible to store multiple items Wh in the bag body 101 from two directions. In this case, the turning-over start portion 13 may be formed near the portion that has been heat-sealed in advance, or may be formed near the portion that will be heat-sealed later.

[0055] <Modification> Fig. 5 is a schematic layout diagram of another example of packaging bag manufacturing apparatus 300A. Packaging bag manufacturing apparatus 300A shown in Fig. 5 differs from packaging bag manufacturing apparatus 300 in the direction in which the sheets are pulled out from first roll 31 and fourth roll 34. Other than this, packaging bag manufacturing apparatus 300A is the same as packaging bag manufacturing apparatus 300 of packaging bag manufacturing apparatus 300A. Therefore, parts of packaging bag manufacturing apparatus 300A that are substantially the same as those of packaging bag manufacturing apparatus 300 are given the same reference numerals, and detailed description of the same parts will be omitted.

[0056] 5, the first roll 31 of the packaging bag manufacturing apparatus 300A is disposed so that the first sheet 21 is pulled out from below the shaft 311. The fourth roll 34 is disposed so that the fourth sheet 24 is pulled out from below the shaft 341.

[0057] That is, the third sheet 23 is wound around the third roll 33 so that the surface facing the first sheet 21 is the corona-treated treated surface 231. The first sheet 21 is wound around the first roll 31 so that the surface facing the third sheet 23 is the corona-treated treated surface 211. The second sheet 22 is wound around the second roll 32 so that the surface facing the fourth sheet 24 is the corona-treated treated surface 221. The fourth sheet 24 is wound around the fourth roll 34 so that the surface facing the second sheet 22 is the corona-treated treated surface 241.

[0058] With this configuration, all rolls can be formed by wrapping the sheet with the treated surface facing inward. For example, if the first sheet 21, second sheet 22, third sheet 23, and fourth sheet 24 all have the same configuration, one type of roll can be used. This reduces the effort and time required to manufacture the packaging bag 100. It also reduces the likelihood of incorrectly attaching the rolls, making it possible to reduce the occurrence of defective products.

[0059] In this embodiment, in order to have the processing surface on the inside of the roll, the first sheet 21 of the first roll 31 is pulled out from below the shaft 311, and the fourth sheet 24 of the fourth roll 34 is pulled out from below the shaft 341.

[0060] However, this is not limiting. The treated surface may be on the outside of the roll, with the first sheet 21 of the first roll 31 being pulled out from above the shaft 311, the second sheet 22 of the second roll 32 being pulled out from below the shaft 321, the third sheet 23 of the third roll 33 being pulled out from below the shaft 331, and the fourth sheet 24 of the fourth roll 34 being pulled out from above the shaft 341. The pulling direction of the sheets relative to the shaft of each roll may be determined by the direction of the corona-treated surface of each sheet or by the layout of the manufacturing equipment.

[0061] <Example> A specific example of a packaging bag according to the present invention will be described. As described above, the first sheet 21, second sheet 22, third sheet 23, and fourth sheet 24 constituting the packaging bag 100 are all formed of polyolefin-based resin. The resins constituting the first sheet 21, second sheet 22, third sheet 23, and fourth sheet 24 will be described in detail.

[0062] The first sheet 21, the second sheet 22, the third sheet 23, and the fourth sheet 24 may all be made of polyethylene (PE) or polypropylene (PP).

[0063] In the packaging bag 100, the first sheet 21, the second sheet 22, the third sheet 23, and the fourth sheet 24 are formed from the same material, but sheets with different heat resistance temperatures, in other words, different melting points, may be used. The packaging bag 100 is thermally bonded by applying heat and pressure from the outside in the stacking direction. Therefore, the outside of the thermally bonded portion 11 has a higher temperature than the inside. For this reason, the third sheet 23 and the fourth sheet 24, which are arranged on the outside, may be made of materials with a higher heat resistance temperature than the first sheet 21 and the second sheet 22, which are arranged on the inside.

[0064] In such a configuration, for example, the first sheet 21 and the second sheet 22 may be made of unstretched polypropylene (CPP), and the third sheet 23 and the fourth sheet 24 arranged on the outside may be made of oriented polypropylene (OPP), which has a higher heat resistance temperature than CPP. By doing so, the first adhesive portion 111 and the second adhesive portion 112 of the thermally bonded portion 11 can be firmly bonded together. Note that, as a method for changing the heat resistance temperature, the difference in heat resistance temperature depending on whether or not the material is stretched, as described above, may be utilized, or the difference in heat resistance temperature depending on the grade may be utilized.

[0065] The thickness of the inner first sheet 21 and second sheet 22 may be different from the thickness of the outer third sheet 23 and fourth sheet 24. For example, by making the thickness of the third sheet 23 and fourth sheet 24 thicker than the thickness of the first sheet 21 and second sheet 22, it is possible to prevent damage to the packaging bag 100 caused by external members when it is used for transportation. Furthermore, by making the thickness of the first sheet 21 and second sheet 22 thicker than the thickness of the third sheet 23 and fourth sheet 24, it is possible to prevent damage to the bag body 101 caused by expansion due to a difference in air pressure.

[0066] When the packaging bag manufacturing apparatus 300 is used, the packaging bag 100 is a four-side sealed pouch. However, the packaging bag 100 is not limited to a four-side sealed pouch. For example, when the packaging bag manufacturing apparatus is configured to manufacture the packaging bag by folding a sheet, it is also possible to manufacture a three-side sealed pouch.

[0067] Although the embodiments of the present invention have been described above, the present invention is not limited to these. Furthermore, various modifications can be made to the embodiments of the present invention without departing from the spirit of the invention. [Industrial Applicability]

[0068] The packaging bag of the present invention can be used as a bag for transporting items that should not be contaminated with foreign matter, such as semiconductor products, silicon wafers, and magnetic disks. [Explanation of symbols]

[0069] 100 packaging bags 101 Bag body 102 Exterior part 10 Containment Space 11 Heat bonding part 111 1st adhesive part 112 2nd adhesive part 12 Notch 13 Beginning of turning 21 Sheet 1 211 Treatment Surface 212 Interior 22 Second Sheet 221 Treatment Surface 222 Interior 23 Third Sheet 231 Processing Surface 24 4th Sheet 241 Treatment Surface 300 Manufacturing equipment 300A manufacturing equipment 301 Laura 31 Roll 1 311 Shaft 32 Roll 2 321 Shaft 33 Third Roll 331 Shaft 34 4th Roll 341 Shaft 35 tables 36 Cutter 351 Positioning part 37 Heat welded part Wh Goods

Claims

1. A packaging bag in which the edges of four stacked sheets are heat-sealed, a first sheet and a second sheet arranged facing each other; a third sheet disposed outside the first sheet; a fourth sheet disposed outside the second sheet, the first sheet, the second sheet, the third sheet, and the fourth sheet are formed of a polyolefin-based resin, at least one of the opposing surfaces of the first sheet and the third sheet and at least one of the opposing surfaces of the second sheet and the fourth sheet are subjected to a corona treatment; The third sheet and the fourth sheet have a higher heat resistance temperature than the first sheet and the second sheet.

2. 2. The packaging bag according to claim 1, wherein both opposing surfaces of the first sheet and the third sheet and both opposing surfaces of the second sheet and the fourth sheet are subjected to a corona treatment.

3. 3. The packaging bag according to claim 1, further comprising an unbonded portion that is not thermally bonded outside the thermally bonded portion.

4. The packaging bag according to claim 3 , wherein an opening start portion is provided in the heat-sealed portion of the first sheet and the second sheet.

5. 5. The packaging bag according to claim 1, wherein the first sheet, the second sheet, the third sheet, and the fourth sheet are all made of polyethylene.

6. 5. The packaging bag according to claim 1, wherein the first sheet, the second sheet, the third sheet, and the fourth sheet are all made of polypropylene.

7. the first sheet and the second sheet are formed of unstretched polypropylene, 7. The packaging bag according to claim 6, wherein the third sheet and the fourth sheet are made of oriented polypropylene.

8. A packaging bag manufacturing device that stacks a first sheet and a second sheet that are arranged facing each other, a third sheet that is arranged outside the first sheet and has a higher heat resistance temperature than the first sheet and the second sheet, and a fourth sheet that is arranged outside the second sheet and has a higher heat resistance temperature than the first sheet and the second sheet, and thermally bonds the peripheries of the four stacked sheets, a first roll on which the first sheet is wound in a roll shape; a second roll on which the second sheet is wound in a roll shape; a third roll on which the third sheet is wound in a roll shape; a fourth roll around which the fourth sheet is wound in a roll shape; a heat welding section for simultaneously heating and pressurizing the peripheral edges of the four sheets pulled out from the respective rolls and stacked together; the third roll, the first roll, the second roll, and the fourth roll are arranged in this order, the third sheet is wound around the third roll so that the surface facing the first sheet is a corona-treated surface; the first sheet is wound around the first roll so that the surface facing the third sheet is a corona-treated surface; the second sheet is wound around the second roll so that the surface facing the fourth sheet is a corona-treated surface; The fourth sheet is wound around the fourth roll so that the surface facing the second sheet is a corona-treated surface.

Images