Packaging bag and manufacturing method thereof

Abstract

To provide a packaging bag in which an adhesive layer can be formed on the inside of the bag body up to both edges, the release liner hardly peels off when storing goods, and both edges of the thermally bonded bag body hardy peel off to form holes, and a manufacturing method thereof.SOLUTION: A bag body 1 is composed of a foamed resin sheet mainly made of thermoplastic resin. A packaging bag is provided with a bottom portion 11 formed by folding back the foamed resin sheet or by thermally bonding the foamed resin sheets together, two side edges portions 12 formed by thermally bonding the foamed resin sheets together, and an opening portion 13 formed on the opposite side of the bottom portion 11. On the inside of the bag body 1 near the opening portion 13, an adhesive layer 2 with a release liner 3 is formed on one of the foam resin sheets in the width direction and, using a material that is thermally fusible to the foam resin sheet for the release liner 3, the two side edge portions 12 on the extended line of the adhesive layer 2 are thermally fused with the release liner 3 sandwiched therebetween.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a packaging bag and a method for producing the same. [Background technology]

[0002] Packaging bags with a cushioning function are known in which the bag body is made of a foamed resin sheet with excellent cushioning properties, and the applicant of this patent has also previously filed a patent application (see Patent Document 1). This type of packaging bag is generally designed to contain an item (e.g., electronic components or fragile items) in the bag body and then seal it by closing the flap, but there are also known bags in which an adhesive layer is formed on the inside of the bag body in order to seal packaging bags that do not have flaps, to improve the sealing performance of the packaging bag, and to make it easier to close the flap of the packaging bag.

[0003] For example, Patent Document 2 describes a paper packaging bag, and discloses a technology for forming an adhesive layer on the inside of the packaging bag to prevent the gusseted portion of the opening from expanding. Although this makes it possible to close the bag by pressing the sheets on the front and back sides of the bag body, it is difficult to form the band-shaped adhesive layer and release liner on both sides of the bag body, so there is a limit to the sealing ability of the bag body.

[0004] In addition, in the packaging bag having the above configuration, since the release liner is merely provided on the adhesive layer and is not fixed to the bag body, when an article is stored in the bag body, the release liner is likely to come into contact with the hand or the article and fall off. In particular, since the release liner is configured to be easily peeled off from the adhesive layer, the release liner is likely to fall off when the bag body is deformed by expanding the opening when storing an article, in addition to when the release liner is directly touched.

[0005] On the other hand, the applicant of the present invention previously proposed a configuration in which a release liner is sandwiched between both side edges of the bag body to be heat-sealed in the packaging bag using the above-mentioned foamed resin sheet, but the resin of the release liner and the resin of the foamed resin sheet of the bag body were incompatible, making it impossible to achieve heat sealing with sufficient strength. As a result, there was a problem that the portions of the bag body where the release liner was sandwiched peeled off, causing partial holes in both side edges. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2022-56096 [Patent Document 2] Utility Model Registration No. 3054038 DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0007] The present invention aims to solve the problems of the conventional technology described above, and in summary, to provide a packaging bag in which an adhesive layer can be formed on the inside of the bag body up to both side edges, which is less likely to cause the problem of the release liner peeling off when storing items, and which is less likely to cause holes due to the heat-sealed both side edges of the bag body peeling off, and a manufacturing method thereof. [Means for solving the problem]

[0008] As a means for solving the above problems, the inventor has constructed a bag body 1 from a foamed resin sheet whose main material is a thermoplastic resin, and has a bottom 11 formed by folding back the foamed resin sheet or by heat-sealing the foamed resin sheets together, both side edge portions 12 formed by heat-sealing the foamed resin sheets together, and an opening 13 formed on the opposite side of the bottom 11, and on the inside of the bag body 1 near the opening 13, an adhesive layer 2 with a release liner 3 is formed in the width direction on one of the foamed resin sheets, and a material that has heat-sealing properties with the foamed resin sheet is used for the release liner 3, so that both side edge portions 12 on the extension of the adhesive layer 2 are heat-sealed with the release liner 3 sandwiched therebetween (the effects will be described later).

[0009] Furthermore, by forming perforations 31 in the release liner 3 near both side edges 12 of the bag body 1 and forming linearly arranged perforations 14 in the bag body 1 at positions corresponding to the perforations 31 of the release liner 3, the perforations 31 can be formed by penetrating the bag body 1 with a cutter after the bag body 1 is formed, and further by tearing the perforations 31, the release liner 3 can be easily separated from the bag body 1.

[0010] On the other hand, by using an easily tearable material for the release liner 3 and forming notches 32 in the release liner 3 near both side edges 12 of the bag body 1, the release liner 3 can be torn at the notches 32 and easily separated from the bag body 1.

[0011] Furthermore, by using polyethylene resin as the main material for both the foamed resin sheet constituting the bag body 1 and the release liner 3, both side edges 12 can be firmly bonded even with heat sealing at a relatively low melting point.

[0012] In addition, in the present invention, the manufacturing method for the above-mentioned packaging bag includes the steps of forming an adhesive layer 2 with a release liner 3 on a foamed resin sheet that is the material for the bag body 1, folding back the foamed resin sheet with the release liner 3 sandwiched inside to form the bottom 11 of the bag body 1, performing a heat press process on the folded back foamed resin sheet to form both side edge portions 12 of the bag body 1, and forming perforations 31 in the release liner 3 by inserting a cutter through the bag body 1 on the inside of both side edge portions 12 of the bag body 1 with the release liner 3 sandwiched between them, thereby easily forming the perforations 31. Effect of the Invention

[0013] In the present invention, in a packaging bag using a foamed resin sheet with cushioning properties, a release liner is sandwiched between and heat-sealed on both side edges of the bag body, and a material that has heat-sealing properties with the foamed resin sheet of the bag body is used for the release liner, making it less likely that the both side edges will peel off, and therefore less likely to cause problems such as holes being made in the both side edges and compromising the seal when the packaging bag is in use.

[0014] In addition, in the present invention, since the release liner is fixed to both side edge portions of the bag body, even if the release liner is touched by a hand or an object when storing an object in the bag body, the release liner does not peel off, and the problem of the adhesive adhering to the hand or the object is unlikely to occur. Also, by fixing the release liner to both side edge portions, it is possible to form the adhesive layer without any gaps up to both side edge portions. [Brief description of the drawings]

[0015] [Figure 1] 1 is an overall perspective view showing a packaging bag according to a first embodiment of the present invention. [Diagram 2] 1 is a partially cutaway plan view showing a packaging bag according to a first embodiment of the present invention. FIG. [Diagram 3] FIG. 11 is a partially cutaway plan view showing a packaging bag according to a modified example of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] "First embodiment" A first embodiment of the present invention will be described with reference to Figs. 1 to 3. In the drawings, the reference B indicates a packaging bag, the reference 1 indicates a bag body, the reference 2 indicates an adhesive layer, and the reference 3 indicates a release liner.

[0017] "Packaging bag composition" [1] Basic structure of packaging bags The basic structure of the packaging bag in this embodiment will be described. First, in this embodiment, as shown in Fig. 1(a)(b) and Fig. 2, the bag body 1 is made of a foamed resin sheet mainly made of thermoplastic resin. Specifically, one foamed resin sheet is folded to form the bottom 11, and the insides of the front and back foamed resin sheets are heat-sealed in a strip shape to form both side edge portions 12, and an opening 13 is formed on the opposite side of the bottom 11. This allows a space to be formed between the front sheet S1 and the back sheet S2 of the bag body 1 for storing items, etc.

[0018] Further, on the inside of the bag body 1 near the opening 13 of the bag body 1, a strip-shaped adhesive layer 2 is formed in the width direction as shown in Fig. 1(b), and further, on this adhesive layer 2, a release liner 3 is provided as shown in Fig. 1(a). This release liner 3 is made of a foamed resin sheet constituting the bag body 1 and a tape having heat-sealing properties, and this release liner 3 is sandwiched between the foamed resin sheets at both side edge portions 12 on the extension of the adhesive layer 2 and is integrated by heat-sealing them.

[0019] [2] How to use packaging bags As shown in Fig. 1(b), the packaging bag of this embodiment can seal the opening 13 of the bag body 1 by peeling off the release liner 3 and crimping the front sheet S1 and back sheet S2 of the bag body 1. When an article is placed in the packaging bag, the release liner 3 and the foamed resin sheet are heat-sealed to form the side edge portions 12, so that the side edge portions 12 of the bag body 1 are unlikely to peel off. In addition, when an article is placed in the bag body 1, the release liner 3 can be prevented from peeling off due to contact with the article or the hand. In addition, since the release liner 3 is provided up to the side edge portions 12 of the bag body 1, the adhesive layer 2 can be formed up to the side edge portions 12 without any gaps.

[0020] [3] About the bag itself [3-1] Materials for foamed resin sheets Next, each component of the packaging bag will be described. In this embodiment, a polyethylene foamed resin sheet having an aluminum vapor deposition layer on the outside is used for the foamed resin sheet of the bag body 1, which reflects heat and prevents the contents from being seen through. By using such a foamed resin sheet, a cushioning function can be imparted to the packaging bag. In addition, as the material for the foamed resin sheet, one or more materials can be used as long as they are mainly made of thermoplastic resin, and resins other than the polyethylene of this embodiment, such as PET resin and polypropylene resin, can also be used. The thickness and foaming ratio of the foamed resin sheet can be appropriately changed depending on the application of the packaging bag.

[0021] In addition, although a single-layer sheet is used for the foamed resin sheet in this embodiment, it is sufficient that the foamed resin sheet has at least a foamed resin layer on the inside, and a multi-layer sheet other than the single-layer sheet can also be used. Specifically, a multi-layer sheet having a paper layer on the outside can be used as an envelope depending on the application. In addition, a multi-layer sheet having a resin film or a metal film on the outside can also be used.

[0022] [3-2] Overall shape of the bag body In this embodiment, as shown in Figures 1(a)(b) and 2, the bag body 1 has a rectangular shape in a plan view, but the overall shape is not limited to a rectangle, and may be, for example, a trapezoid in which the width of the bottom 11 is greater than the opening 13, or a semicircular or semielliptical shape. In this embodiment, a flap is formed on the back sheet S2 of the bag body 1 as shown in Figures 1(a)(b) so that it can be used as a lid, but the presence or absence of a flap and the shape of the flap can be appropriately changed depending on the application of the packaging bag and the required functions.

[0023] [3-3] Bottom and both side edges In the present embodiment, the bottom 11 of the bag body 1 is formed by folding back one foamed resin sheet, but the bottom 11 can also be formed by heat-sealing two foamed resin sheets together. In that case, it is preferable to form a band-shaped heat-sealed portion, similar to the both side edges 12. When the both side edges 12 and the bottom 11 of the bag body 1 are heat-sealed in a band shape, it is preferable to ensure sufficient peel strength by heat sealing so that the front sheet S1 and the back sheet S2 do not peel off and cause holes in the bag. In this embodiment, the foamed resin sheet constituting the bag body 1 and the release liner 3 are mainly made of the same type of polyethylene resin, so that the entire both side edges 12 can be firmly bonded (heat-sealed) by heat sealing. The foamed resin sheet of the bag body 1 can be made of the same type of resin as the release sheet 3, or a resin with high compatibility.

[0024] [3-4]Perforation 1(a)(b) and 2, in this embodiment, perforations 14 are formed in a line in the depth direction of the bag in the foamed resin sheet near the opening of the bag body 1. These are formed at the same time as forming perforations in the release liner 3 described below, but each of the perforations is small and appears to be blocked due to the shape restoration property of the foamed resin sheet, so they do not significantly impair the sealability of the bag body 1.

[0025] [4] About the adhesive layer Next, with regard to the adhesive layer 2, a rubber-based adhesive is used in this embodiment, but other adhesives, such as acrylic adhesives, silicone adhesives, and urethane adhesives, can be used depending on the compatibility with the items and foamed resin sheet contained in the bag body. In this embodiment, the adhesive layer 2 is formed in a strip shape as shown in FIG. 1(b), but multiple adhesive layers 2 can be formed in the bag body 1. The vertical width of the adhesive layer 2 can be appropriately changed depending on the size of the bag body 1 and the required adhesive strength, and the horizontal length of the adhesive layer 2 is preferably formed without gaps up to both side edges 12 of the bag body 1, but if there is another sealing means such as a flap, the length of the adhesive layer 2 is not particularly limited.

[0026] The position where the adhesive layer 2 is formed is not particularly limited as long as it is near the opening 13 of the bag body 1. In this embodiment, the adhesive layer 2 is formed only on the back sheet S2 of the bag body 1 on which the flap is formed, but the adhesive layer 2 can also be formed only on the front sheet S1 side, or on both the front sheet S1 and the back sheet S2.

[0027] [5] Release liner [5-1] Release liner material In this embodiment, the release liner 3 is made of the same polyethylene resin (HDPE) as the thermoplastic resin of the foamed resin sheet, and a silicone coating layer is formed on the release surface (rear surface). The release liner 3 protects the adhesive surface and is easily peeled off from the adhesive surface when used, and is also called a separator, release paper, release paper, or release film. The base material of the release liner 3 can be the same as the thermoplastic resin of the foamed resin sheet, or one or more materials having excellent compatibility with the thermoplastic resin of the foamed resin sheet. When a different resin is used for the foamed resin sheet, a PET resin, a polypropylene resin, or the like can be used accordingly. In this embodiment, an unstretched film is used for the release liner 3, but a stretched film (uniaxially stretched or biaxially stretched) having easy tearability can also be used.

[0028] The release liner 3 may be configured as long as the substrate is made of a thermoplastic resin, and may be a multi-layer film in addition to a single-layer film. In this embodiment, an aluminum vapor deposition layer is formed on the surface side of the release liner 3, but a colorant may be added instead of the aluminum vapor deposition layer. An antistatic agent is added to the silicone coating layer to prevent "peeling static electricity," but antioxidants, ultraviolet absorbing agents, etc. may also be added as necessary. A non-silicone coating layer may also be used as the release coating layer on the release surface.

[0029] [5-2] Release liner shape In this embodiment, the release liner 3 is in the form of a tape (strip) that is wider than the adhesive layer 2, but the detailed shape of the tape is not particularly limited. In this embodiment, perforations 31 are formed in the vicinity of both side edges 12 of the release liner 3 as shown in Fig. 2, and the release liner 3 can be easily separated from the bag body 1 by tearing the perforations 31 in the vertical direction as shown in Fig. 1(b). The linearly arranged perforations 14 formed in the bag body 1 are formed along the positions of the perforations 31 of the release liner 3.

[0030] [5-3] Example of changing the shape of the release liner In this embodiment, perforations 31 are used as a means for easily tearing the release liner 3, but an easily tearable material can also be used for the base material of the release liner 3. Furthermore, as shown in Figure 3, notches 32 can be formed near both side edges 12 of the bag body 1 so that the release liner 3 can be easily separated from the bag body 1 by tearing the release liner 3 from the notches 32. The shape of the notches 32 is not particularly limited, and can be a notch, a slit, or a depression.

[0031] "Manufacturing method for packaging bags" Next, a method for manufacturing the packaging bag is described. First, an adhesive layer 2 with a release liner 3 is formed on a foamed resin sheet, which is the material for the bag body 1. Specifically, an adhesive is applied in a strip shape to a foamed resin sheet moving on a conveyor, and the release liner 3 is placed on the adhesive layer 2 thus formed. Next, the foamed resin sheet is folded back with the release liner 3 sandwiched inside to form the bottom 11 of the bag body 1, and the folded back foamed resin sheet is subjected to a heat press process to form both side edge parts 12 of the bag body 1. Specifically, a foamed resin sheet moving on a conveyor is subjected to a heat press process intermittently over a predetermined width (twice the width of both side edge parts 12).

[0032] Next, a cutter is inserted into the inside of both side edge portions 12 of the bag body 1 with the release liner 3 sandwiched therebetween so as to penetrate the bag body 1, forming perforations 31 in the release liner 3. At this time, perforations 14 are formed in the bag body 1 at the same time as the perforations 31. The size and shape of the perforations 31 can be appropriately changed depending on the shape of the cutter. This makes it possible to easily form the perforations 31 in the release liner 3 on the inside of the bag body 1. Finally, the portions of both side edge portions 12 that have been subjected to the above-mentioned heat press processing are cut in the middle, and the connected bag body 1 is separated, thereby continuously producing packaging bags. EXAMPLES

[0033] [Effectiveness verification test] Next, a verification test of the effect of the present invention will be described. In this test, samples of the following Example 1 and Comparative Example 1, which have different materials for the release liners of the packaging bags, were prepared, and the state of both side edge portions 12 of each bag body 1 was confirmed.

[0034] "Example 1" In the first embodiment, polyethylene resin was used for the foamed resin sheet, and a 25 μm thick polyethylene resin (HDPE) film was used for the base material of the release liner. These were heat-sealed by hot pressing to form both side edge portions 12 of the bag body 1.

[0035] "Comparative Example 1" The same foamed resin sheet as in Example 1 was used, but the material of the release liner 3 was changed to a PET resin film having a thickness of 12 μm. Then, these were subjected to the same heat press processing as in Example 1 to form the side edge portions 12 of the bag body 1.

[0036] [Demonstration test results] In the sample of Example 1, both side edge portions 12 were securely heat-sealed throughout, including the portion where the release liner 3 was sandwiched, whereas in the sample of Comparative Example 1, the portion where the release liner 3 was sandwiched was not heat-sealed and peeled off, resulting in holes in both side edge portions 12. This confirmed the effect of heat fusion in Example 1. [Explanation of symbols]

[0037] 1 bag body 11 Bottom 12 Side 13 Opening 14 Perforation 2 Adhesive layer 3 Release Liner 31 Perforation 32 Notch S1 front sheet S2 back sheet

Claims

1. The bag body is made of a foamed resin sheet mainly made of a thermoplastic resin, and has a bottom formed by folding the foamed resin sheet or by heat-sealing the foamed resin sheets together, both side edges formed by heat-sealing the foamed resin sheets together, and an opening formed on the opposite side of the bottom, A packaging bag in which an adhesive layer with a release liner is formed in the width direction on one of the foamed resin sheets on the inside of the bag body near the opening, and a material that has heat-sealing properties with the foamed resin sheet is used for the release liner, and both side edges on the extension line of the adhesive layer are heat-sealed with the release liner sandwiched therebetween.

2. 2. The packaging bag according to claim 1, wherein the release liner has perforations formed near both side edges of the bag body, and the bag body has linearly arranged perforations formed at positions corresponding to the perforations of the release liner.

3. 2. The packaging bag according to claim 1, wherein the release liner is made of an easily tearable material and has notches formed in the release liner near both side edges of the bag body.

4. 3. The packaging bag according to claim 1, wherein the foamed resin sheet constituting the bag body and the release liner are each primarily made of a polyethylene resin.

5. A method for manufacturing a packaging bag, comprising the steps of: forming an adhesive layer with a release liner on a foamed resin sheet that is the material of the bag body; folding back the foamed resin sheet with the release liner sandwiched inside to form the bottom of the bag body; hot pressing the folded back foamed resin sheet to form both side edge portions of the bag body; and inserting a cutter through the bag body into the inside of both side edge portions of the bag body with the release liner sandwiched therebetween to form perforations in the release liner.

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