Packaging bags

Abstract

To provide a packaging bag that allows for smooth inversion of the lid, is not bulky, and can be manufactured efficiently. [Solution] The first sheet S1 constituting the bag body 1 of the packaging bag B is made of a thermoplastic resin bubble sheet or foamed resin sheet, and the bag body 1 is made to have a bottom portion 11 formed by folding back or heat-sealing the first sheet S1, side edge portions 12 formed by heat-sealing the first sheets together, and an opening 13 formed on the opposite side of the bottom portion 11. On the other hand, the second sheet S2 constituting the lid 2 is made of a thermoplastic resin sheet, and the second sheet S2 is placed on one surface of the bag body 1 in a double state, folded back on the opening side of the bag body 1, with both ends in the width direction heat-sealed to the side edge portions 12 of the first sheet S1, and the outer sheet portion 21 of the lid 2 is turned inside out to the other surface side of the bag body 1, so that the lid 2 is attached to the opening of the bag body 1.

Description

Technical Field

[0001] The present invention relates to a packaging bag having a lid at an opening.

Background Art

[0002] Conventionally, as packaging materials having a cushioning function, foamed resin cushioning sheets and bubble cushioning sheets are known, and packaging bags using these cushioning sheets are also known. Further, as a bag made of non-woven fabric or the like (for example, a tea bag), a structure having a turned-back lid whose both side edges are heat-sealed or adhered at an opening, and closing the opening by turning back this lid is also known.

[0003] And conventionally, in a packaging bag using the above cushioning sheet, a technique of providing the above turned-back lid at an opening is also known (see Patent Document 1). However, regarding this technique, since the structure was such that both side edges of the turned-back lid were firmly heat-sealed in a strip shape, the strip-shaped heat-sealed portion was caught inside the lid in a closed state of the lid, and the packaging bag was likely to lose its shape.

[0004] Further, in the above conventional packaging bag, since the convex portions (bubbles) of the bubble cushioning sheet were arranged up to the vicinity of both side edges of the turned-back lid, after turning back the lid, the lid was lifted from the bag body by the convex portions in the vicinity of both side edges, and there was a drawback that it was difficult to close the lid. Also, due to the bulkiness of both sides of the turned-back lid, it was difficult to smoothly perform the operation of turning back the lid.

[0005] Therefore, the applicant of the present application made a device to improve the sealing strength on both sides of the turned-back lid and filed a patent application (see Patent Document 2). However, regarding this technique, since the same sheet was used for the bag body and the lid body, when a bubble cushioning sheet or a thick foamed resin sheet was used for the bag body, a bubble portion was also formed in the lid body, the packaging bag was bulky, and there was also a problem in terms of the operation of turning back the lid.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2005-239238 [Patent Document 2] Patent No. 7473196 [Disclosure of the Invention] [Problems that the invention aims to solve]

[0007] The present invention aims to solve the problems of the prior art described above, and in summary, to provide a packaging bag that allows for smooth inversion of the lid, is not bulky, and can be manufactured efficiently. [Means for solving the problem]

[0008] As a means of solving the above problems, the present inventor has configured the first sheet S1 constituting the bag body 1 of the packaging bag B to be made of a thermoplastic resin bubble sheet or foamed resin sheet, and the bag body 1 to be made of a bottom portion 11 formed by folding back or heat-sealing the first sheet S1, both side edges 12 formed by heat-sealing the first sheets together, and an opening 13 formed on the opposite side of the bottom portion 11, while using a thermoplastic resin sheet for the second sheet S2 constituting the lid 2, and arranging the second sheet S2 on one surface of the bag body 1 in a double state folded back on the opening side of the bag body 1, with both ends in the width direction heat-sealed to both side edges 12 of the first sheet S1, and turning the outer sheet portion 21 of the lid 2 inside out to the other surface side of the bag body 1 so that the lid 2 can be attached to the opening of the bag body 1.

[0009] In this invention, the second sheet S2 constituting the lid 2 can be made from a non-foamed sheet, thereby reducing the thickness of the lid 2. As a result, the packaging bag B is not bulky and the lid 2 can be easily turned inside out.

[0010] In the present invention, the first sheet S1 constituting the bag body 1 and the second sheet S2 constituting the lid 2 can be made from the same type of thermoplastic resin, thereby increasing the fusion strength between the bag body 1 and the lid 2 and suppressing the peeling of the lid 2 when the bag is turned inside out.

[0011] In this invention, polyethylene can be used as the main material for the first sheet S1 that constitutes the bag body 1 and the second sheet S2 that constitutes the lid 2, thereby allowing the bag body 1 and the lid 2 to be firmly bonded together by low-melting-point heat sealing.

[0012] In this invention, the inner sheet portion 22 of the lid 2 is made longer in the depth direction of the bag body 1 than the outer sheet portion 21, thereby creating a gap between the bag body 1 and the lid 2, which can be used as a pocket for inserting a name tag or the like to indicate the contents.

[0013] In this invention, the bottom portion 11 of the inner sheet portion 22 of the lid 2 is heat-sealed or bonded to the bag body 1. A pocket can be formed for inserting a name tag or the like to indicate the contents.

[0014] In the present invention, the method for manufacturing the packaging bag B includes the steps of: folding a first sheet to form the bottom of the bag body; and placing a second sheet, which has its opening folded over, on top of the first sheet, which has its bottom folded over, and then performing a heat cutting or heat pressing process to form both side edges of the bag body, as well as attaching a lid to both side edges. This method allows for the efficient manufacture of the packaging bag B. [Effects of the Invention]

[0015] In this invention, the bag body and lid of the packaging bag are constructed from separate sheets. The second sheet of the lid is placed on one surface of the bag body in a double-layered state, folded over at the opening side of the bag body. The outer sheet portion of the lid is then turned over to the other surface of the bag body, so that the lid can be attached to the opening of the bag body. This configuration allows for easy and smooth opening and closing of the lid.

[0016] In the present invention, by using a sheet different from the bag body for the lid as described above, even when a bubble cushion sheet or a thick foamed resin sheet is used for the bag body, the bulkiness of the packaging bag can be suppressed. Furthermore, in the present invention, since the heat sealing of both side edges of the first sheet of the bag body and the heat sealing of the second sheet of the lid can be performed simultaneously, the manufacturing efficiency is also excellent.

Brief Explanation of Drawings

[0017] [Figure 1] (a) An overall front view showing the packaging bag of the first embodiment of the present invention, and (b) An enlarged cross-sectional view taken along line X-X showing the cross-sectional structure of the packaging bag. [Figure 2] A cross-sectional view taken along line Y-Y showing the cross-sectional structure of the packaging bag of the first embodiment of the present invention. [Figure 3] (a) A cross-sectional view taken along line Y-Y showing the state where the lid covers the bag body of the first embodiment of the present invention, and an enlarged cross-sectional view taken along line X-X. [Figure 4] (a) A cross-sectional view showing a modified example of the lid of the first embodiment of the present invention, and (b) A cross-sectional view showing another modified example. [Figure 5] An overall front view showing a modified example of the packaging bag of the first embodiment of the present invention. [Figure 6] (a) A cross-sectional view taken along line Y-Y showing the packaging bag of the second embodiment of the present invention, and (b) A cross-sectional view taken along line Y-Y showing the state where the lid is closed.

Modes for Carrying Out the Invention

[0018] 『First Embodiment』 The first embodiment of the present invention will be described based on FIGS. 1 to 5. In the figures, what is indicated by reference sign B is the packaging bag, and what is indicated by reference sign S is the sheet constituting the bag body and the lid. Also, what is indicated by reference sign 1 is the bag body constituting the packaging bag, and what is indicated by reference sign 2 is the lid of the packaging bag.

[0019] 「Configuration of the Packaging Bag」 [1] Regarding the basic configuration of the packaging bag The basic structure of the packaging bag B of this embodiment will be described. In this embodiment, as shown in FIGS. 1(a)(b) and FIG. 2, the bag body 1 of the packaging bag B includes a bottom portion 11 formed by folding back the first sheet S1, both side edge portions 12 formed by thermally welding the first sheets S1 together, and an opening portion 13 formed on the opposite side of the bottom portion 11, and has a bag shape. The first sheet S1 forming the bag body 1 is made of a bubble sheet made of a thermoplastic resin, and is folded back so that the surface on which the bubbles are formed faces the inside of the bag body 1.

[0020] On the other hand, the second sheet S2 constituting the lid 2 of the packaging bag B is made of a thermoplastic resin sheet. This second sheet S2 is folded back on one surface of the bag body 1 on the opening portion 13 side of the bag body 1 and arranged in a double state, and both ends in the width direction are thermally welded to both side edge portions 12 of the first sheet S1 constituting the bag body 1. As a result, as shown in FIGS. 3(a)(b), by simply turning the outer sheet portion 21 of the lid 2 to the other surface side of the bag body 1, the lid 2 can be put on the bag body 1 so as to close the opening portion of the bag body 1.

[0021] Also, by configuring the lid 2 of the packaging bag B as described above, if the outer sheet portion 21 constituting the lid 2 is turned back once again, it will return to the original state shown in FIG. 2, so that the opening 13 of the bag body 1 can be easily opened and closed. Furthermore, since the thermal welding of both side edge portions 12 of the first sheet S1 of the bag body 1 and the thermal welding of the second sheet S2 of the lid can be performed simultaneously by hot pressing or fusing, the production can also be carried out efficiently.

[0022] [2] About the bag body [2-1] Material of the first sheet Next, each component of the packaging bag B will be described. First, regarding the first sheet S1 constituting the bag body 1, in this embodiment, a bubble cushion sheet having a large number of bubble portions formed on one side is used. As this bubble cushion sheet, a known cushion sheet composed of a base film layer and a bubble film layer can be used. As a sheet other than the bubble cushion sheet, a foamed resin cushion sheet can be used, and in that case, a known cushion sheet composed of a base film layer and a foamed resin layer can be used.

[0023] In this embodiment, low-melting-point low-density polyethylene (LDPE) is used as the main material for the bubble cushioning sheet. However, other thermoplastic resins such as high-density polyethylene (HDPE), polypropylene, polystyrene resin, PET resin, thermoplastic elastomer, or mixtures thereof can also be used. Similarly, in the case of foamed resin cushioning sheets, the appropriate resin material can be selected.

[0024] [2-2]Bottom In this embodiment, the bottom 11 of the bag body 1 is formed by folding a single first sheet S1 downwards as shown in Figure 2. However, the bottom 11 can also be formed by constructing the first sheet S1 from multiple sheets and heat-welding the first sheets S1 together in the same way as the side edges 12. In that case, different bubble wrap or foamed resin cushioning sheets can be used for the multiple first sheets S1.

[0025] [2-3] Overall shape of the bag Regarding the overall shape of the bag body 1, in this embodiment it is rectangular in front view as shown in Figure 1(a). However, as long as the lid 2 can be turned inside out to close the opening 11 of the bag body 1, it is not limited to this shape and can be appropriately changed to a rectangular or polygonal shape with a different aspect ratio, or a shape with a rounded bottom, depending on the intended use of the packaging bag B.

[0026] [3] Regarding the lid [3-1] Materials for the second sheet The second sheet S2 that constitutes the lid 2 is made of the same type of thermoplastic resin as the first sheet S1 that constitutes the bag body 1. This increases the fusion strength between the bag body 1 and the lid 2, suppressing the peeling of the lid 2 when it is turned inside out. Furthermore, a non-foamed sheet is used for the second sheet S2 that constitutes the lid 2, which allows the thickness of the lid 2 to be reduced as shown in Figure 1(b), so that the packaging bag B is not bulky and the lid 2 can be easily turned inside out.

[0027] In this embodiment, polyethylene is used as the main material of the second sheet S2 that constitutes the lid 2. This allows the bag body 1 and the lid 2 to be firmly bonded together by a low-melting-point heat seal. As the main material of the second sheet S2, low-density polyethylene (LDPE), high-density polyethylene (HDPE), other polyolefin resins such as polypropylene, polystyrene resin, PET resin, thermoplastic elastomer, or a mixture of these resins can be used.

[0028] [3-2] Outer sheet section and inner sheet section As shown in Figures 1(b) and 2, the lid 2 has a shape comprising an outer sheet portion 21 and an inner sheet portion 22. In this embodiment, the second sheet S2 is folded back on the side of the opening 13 of the bag body 1 to form the outer sheet portion 21 and the inner sheet portion 22. This folded portion on the side of the opening 13 of the bag body 1 can also be formed by fusing or bonding multiple sheets together.

[0029] In this embodiment, the inner sheet portion 22 of the lid 2 is composed of a single sheet. However, if the second sheet S2 consists of multiple sheets, the inner sheet portion 22 can also be composed of multiple sheets. Furthermore, if the second sheet S2 consists of multiple sheets, sheets of different materials and thicknesses can be combined and used.

[0030] [3-3] Gap between the lid and the bag body As shown in Figure 1(a), the inner sheet portion 22 of the lid 2 is heat-sealed to the edges 12 on both sides of the bag body 1. Therefore, in the state shown in Figure 2, when the lid 2 is not placed over the bag body 1, a gap (unfused / non-adhesive portion) can be formed between the inner sheet portion 22 and the bag body 1, and this gap can be used as a pocket for inserting a name tag or other item to indicate the contents.

[0031] [3-4] Heat-sealed joints on both sides Regarding the heat sealing of the lid 2 and the side edges 12 of the bag body 1, and the heat sealing of the outer sheet portion 21 and inner sheet portion 22 on both sides in the width direction of the lid 2, stress is likely to be placed when the lid 2 is placed over the bag body 1 when it is inflated with contents inside, or when the lid 2 is repeatedly opened and closed. For this reason, it is preferable to perform heat sealing by cutting or heat pressing to achieve a seal strength of a certain level or higher.

[0032] [3-5] Examples of changes to the outer and inner sheet sections In this embodiment, as shown in Figures 1(a) and 2, the outer sheet portion 21 and the inner sheet portion 22 of the lid 2 are formed to have the same vertical width. However, as shown in Figures 4(a) and 4(b), the inner sheet portion 22 can also be formed to be longer than the outer sheet portion 21 in the depth direction of the bag body 1. This increases the area of ​​the inner sheet portion 22, making it easier to use as a pocket for name tags and the like.

[0033] Furthermore, if the inner sheet portion 22 is formed to be longer than the outer sheet portion 21 in the depth direction of the bag body 1 as described above, the lower edge portion 23 of the inner sheet portion 22 can be bonded or heat-sealed to the bag body 1, as shown in Figure 5. This prevents name tags, cards, etc., from falling out when the gap between the inner sheet portion 22 and the bag body 1 is used as a pocket. In this embodiment, the entire lower edge portion 23 of the inner sheet portion 22 is bonded in a strip shape, but it is also possible to partially bond or heat-seal the portion on the bottom 11 side of the bag body 1.

[0034] "Second Embodiment" A second embodiment of the present invention will be described with reference to Figure 6. In this embodiment, as shown in Figure 6(a), the bag body 1 of the packaging bag B is made thick, and one side of the front and back surfaces of the bag body 1 is formed to be longer above the other side (opposite to the bottom 11), so that the extended portion 14 can be placed over the top of the article G contained in the bag body 1 and the lid 2 can be attached, as shown in Figure 6(b). This makes it possible to protect the top of the contained article G with the first sheet S1.

[0035] Furthermore, when forming the extension 14 on the opening 13 side of the bag body 1 as described above, in this embodiment, the extension 14 is formed on the side to which the lid 2 is attached, as shown in Figure 6(a). However, the extension 14 can also be formed on the other side to which the lid 2 is not attached, or the extension 14 can be formed on both the front and back surfaces of the bag body 1. The other configurations are the same as in the first embodiment.

[0036] "Manufacturing method for packaging bags" [1] Basic process Next, the manufacturing method of the packaging bag B described above will be explained. First, a first sheet S1 and a second sheet S2, which are continuous in the length direction (width direction of the packaging bag B), are continuously supplied in a folded state by a conveyor device. Then, the packaging bag B is divided by cutting these continuously supplied first sheet S1 and second sheet S2 at regular intervals with a cutter, and at the same time, the edges on both sides of the folded bag body 1, the parts on both sides of the lid, and the bag body 1 and lid 2 are heat-sealed.

[0037] As a method for manufacturing the above-mentioned packaging bag B, any other method can be adopted, as long as it includes the steps of folding back the first sheet S1 to form the bottom of the bag body 1, and placing the second sheet S2, which has its opening side folded back, on top of the first sheet S1 with its bottom side folded back, and then performing a heat cutting or heat pressing process to form both side edges 12 of the bag body 1, and attaching the lid 2 to both side edges.

[0038] [2] Cutting of the outer sheet portion As a method for manufacturing the above-described packaging bag B, when the inner sheet portion 22 is formed to be longer in the depth direction of the bag body 1 than the outer sheet portion 21, as shown in Figures 4(a) and 4(b), after heat-sealing the bag body 1 and the lid 2, only the second sheet S2 constituting the outer sheet portion 21 can be partially cut to shorten its vertical width. This is because it is difficult to change the folding position of the second sheet when heat-sealing continuously using a belt conveyor or the like.

[0039] [3] Adhesion or heat sealing of the lower edge of the lid When the inner sheet portion 22 is formed to be longer in the depth direction of the bag body 1 than the outer sheet portion 21, after cutting the second sheet S2, the lower edge portion 23 of the inner sheet portion 22 and the bag body 1 are bonded or heat-sealed as shown in Figure 5.

[0040] [4] Examples of changes to the hot press process In this embodiment, the bag body 1 and lid body 2 are cut and heat-sealed simultaneously by thermal cutting, but each process can also be performed in stages. In this embodiment, a double-edged cutter is used, but the area of ​​the heat-sealed part can be increased by heat pressing by devising the shape of the cutter blade, such as a stepped type. Furthermore, the seal strength can be appropriately adjusted by the temperature, time, and pressure of the heat press. [Explanation of symbols]

[0041] 1 bag (main body) 11 Bottom 12 Both sides 13 Opening 2 Lid 21 Outer sheet section 22 Inner sheet section S1 First Seat S2 Second Seat B Packaging bag

Claims

1. The first sheet constituting the bag body is made of a thermoplastic resin bubble sheet or foamed resin sheet, and the bag body is constructed to have a bottom formed by folding or heat-sealing the first sheet, both side edges formed by heat-sealing the first sheets together, and an opening formed on the opposite side of the bottom, A thermoplastic resin sheet is used for the second sheet that constitutes the lid, and the second sheet is placed on one surface of the bag body in a double state, folded over at the opening side of the bag body, with both ends in the width direction heat-sealed to both side edges of the first sheet. A packaging bag in which the outer sheet portion of the lid is turned inside out to face the other side of the bag body, and the lid is attached to the opening of the bag body.

2. The packaging bag according to claim 1, wherein the second sheet constituting the lid is made of a non-foamed sheet.

3. The packaging bag according to claim 1 or 2, wherein the first sheet constituting the bag body and the second sheet constituting the lid are made of the same type of thermoplastic resin.

4. The packaging bag according to claim 1 or 2, wherein polyethylene is used as the main material for the first sheet constituting the bag body and the second sheet constituting the lid.

5. The packaging bag according to claim 1 or 2, wherein the inner sheet portion of the lid is formed to be longer in the depth direction of the bag body than the outer sheet portion, and a gap is formed between the bag body and the lid.

6. The packaging bag according to claim 1 or 2, wherein the bottom portion of the inner sheet of the lid is heat-sealed or bonded to the bag body.

7. A method for manufacturing a packaging bag, comprising the steps of: folding a first sheet to form the bottom of the bag body; and placing a second sheet, with the opening side folded over, on top of the first sheet with the bottom side folded over, and performing a heat cutting or heat pressing process to form both side edges of the bag body, and attaching a lid to both side edges.

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