JP7557585B2 - Self-standing bag - Google Patents

Description

This disclosure relates to a self-supporting bag.

Standing pouches and other self-supporting bags have been known that have a body and a bottom, with the bottom formed in a gusseted format (see, for example, Patent Documents 1 to 3).

JP 2012-66828 A JP 2011-195175 A JP 2019-6435 A

In the self-supporting bag as in Patent Document 1, side seals are applied to the left and right edges. Because this side seal is very rigid, when a consumer holds the bag in their hand, the side seal hits the consumer's hand, causing pain in the hand, and thus causing problems in usability. In addition, the self-supporting bag with side seals as in Patent Document 1 is manufactured by folding the bottom film in half with the base film layer side such as nylon on the inside and the sealant layer side such as polyethylene on the outside, inserting the bottom film in half between the front and back body films, and heat-bonding the peripheral edges of the bottom film and the body film together. At this time, the opposing surfaces of the bottom film facing the inside of the folded state are made of a high melting point film such as nylon, so they are not heat-bonded to each other. This may cause the self-supporting bag to become unstable. Therefore, a method may be adopted in which a cutout is provided in a part of the left and right edges of the bottom film to expose the body film, and the exposed body films are heat-bonded to each other. However, this method increases the number of manufacturing steps for the self-supporting bag, and there is a problem that the cost is relatively high because scrap material is generated when the cutout is provided. In addition, because the scraps are small, they tend to scatter, which reduces production efficiency. Furthermore, the self-supporting bags in Patent Documents 2 and 3 do not have side seals, but the bottom member and the body are bonded with a separate adhesive member, making the structure complex. This causes problems such as reduced production efficiency and manufacturing defects such as poor adhesion. Furthermore, the bag body made of a cylindrical film has low rigidity, which causes constrictions and distortions, making it unstable to stand on its own.

In addition, rigid containers such as plastic bottles are widely used as containers for beverages and other liquids. However, rigid containers are difficult to crush when discarding, and even if they are crushed, they produce a lot of waste. Therefore, there is a demand for containers that can replace rigid containers.

The objective of this disclosure is to provide a self-supporting bag that has an aesthetic appearance that can be used as a substitute for rigid containers for liquids, is environmentally friendly, can reduce manufacturing costs, and does not cause discomfort when the body is held in the hand.

The self-supporting bag according to the present invention comprises a body portion having a flattened body film in a cylindrical shape with open top and bottom ends and creases on the left and right edges, and a bottom gusset having a flat bag-shaped bottom film with an open edge at the bottom end inserted into the lower end of the body portion with the open edge facing down, the body film and the bottom film being fixed together with a bottom seal, the bottom seal having at least a first seal portion in which the lower end of the bottom film is bonded to the inner surface of the lower end of the body film around the entire circumference of the bottom film, and the bottom gusset has a first seal portion bonded to the open edge, an upper closed edge opposite the open edge, and a left closed edge of the open edge. the left closed edge connecting the right end of the open edge to the left end of the upper closed edge, and the right closed edge connecting the right end of the open edge to the right end of the upper closed edge, wherein the upper closed edge is an adhesive joint between the opposing ends of the bottom film or is a fold in the bottom film, and the left closed edge and the right closed edge are both adhesive joints between the opposing ends of the bottom film, or either one of the left closed edge and the right closed edge is an adhesive joint between the opposing ends of the bottom film, and the other of the left closed edge and the right closed edge is a fold in the bottom film.

The self-supporting bag according to the present invention includes a configuration in which the bottom film is a single sheet-like film, the upper closed edge is the fold line, which is a fold line formed by folding the single sheet-like film in half, the open edge is a portion where the inner surfaces of the sheet-like film are not bonded together at the edge opposite the fold line, and the left closed edge and the right closed edge are both the adhesive portion, which is a portion where the inner surfaces of the sheet-like film are bonded together at both edges extending from both ends of the fold line.

In the self-supporting bag according to the present invention, the bottom film is two sheet-like films, the open edge is a portion where the inner surfaces of the two sheet-like films overlapped at one edge of the periphery are not bonded to each other, and the top closed edge, the left closed edge, and the right closed edge are all the adhesive portion, and the adhesive portion includes a form where the inner surfaces of the two sheet-like films overlapped at the remaining edge of the periphery are bonded to each other.

The self-supporting bag according to the present invention includes a configuration in which the bottom film is a single sheet-like film, either the left closed edge or the right closed edge is the fold, which is a fold created by folding the single sheet-like film in half, the other of the left closed edge or the right closed edge is the adhesive portion, which is a portion where the inner surfaces of the sheet-like film are adhered to each other at an edge that faces the fold, the top closed edge is the adhesive portion, which is a portion where the inner surfaces of the sheet-like film are adhered to each other at an edge that extends from one end of the fold, and the open edge is a portion where the inner surfaces of the sheet-like film are not adhered to each other at an edge that extends from the other end of the fold.

The self-supporting bag according to the present invention preferably has a gap between the inner wall at the left edge of the body and the bottom gusset or between the inner wall at the right edge of the body and the bottom gusset, or both, and the bottom seal preferably further has a second seal portion in which the inner surfaces of the body films are bonded to each other in the gap. By having a gap, the bottom film can be more easily inserted into the lower end of the body film.

The self-supporting bag according to the present invention preferably further has a reinforcing seal in the region spanning the first seal and the second seal. The reinforcing seal can prevent pinholes from occurring at the boundary between the first seal and the second seal.

In the self-supporting bag according to the present invention, the bottom seal has a left inclined seal portion that extends diagonally between the open edge and the left closed edge, and a right inclined seal portion that extends diagonally between the open edge and the right closed edge, and it is preferable that the left inclined seal portion and the right inclined seal portion are portions where the inner surfaces of the opposing body films and the bottom film are bonded together. By providing the left inclined seal portion and the right inclined seal portion, the bottom gusset can be held within the body, allowing the bag to stand on its own more stably.

In the self-supporting bag according to the present invention, the bottom gusset has a left corner formed by the left end of the top closed edge and the top end of the left closed edge, and a right corner formed by the right end of the top closed edge and the top end of the right closed edge, and the bottom seal preferably has point seal parts at the left corner and right corner that partially bond the bottom film to the inner surfaces of the opposing body films. By providing point seal parts, the bottom gusset can be held inside the body, allowing it to stand on its own more stably.

This disclosure makes it possible to provide a self-supporting bag that has an aesthetic appearance that can be used as a substitute for rigid liquid containers, is environmentally friendly, has low manufacturing costs, and does not cause discomfort when the body is held in the hand.

FIG. 2 is a schematic front view showing an example of a self-standing bag according to the present embodiment. 2 is a schematic end view of line AA in FIG. 1. FIG. 2 is a schematic diagram showing a first example of a bottom film. FIG. 2 is a schematic diagram showing a second example of the bottom film. FIG. 11 is a schematic diagram showing a third example of a bottom film. A schematic diagram showing a fourth example of a bottom film. A schematic diagram showing a fifth example of a bottom film. 2 is a schematic partial enlarged view of an area B surrounded by a dashed dotted line in FIG. 1 . FIG. 2 is a schematic partial front view showing an example of a self-standing bag according to the present embodiment, the bag having an inclined seal portion. FIG. 2 is a schematic partial front view showing an example of a self-standing bag according to the present embodiment, the bag having a spot seal portion. 1A to 1D are diagrams for explaining the manufacturing method of the self-supporting bag according to the present embodiment, in which (a) is a diagram for explaining steps 1 and 2, (b) is a diagram for explaining step 3, (c) is a diagram for explaining step 4, and (d) is a diagram for explaining step 5, and (e) is a schematic diagram of the self-supporting bag after step 5. 1A and 1B are diagrams for explaining an example of a method for manufacturing a conventional self-standing bag, in which (a) is a schematic diagram showing the shape of a body film and a bottom film, and (b) is a schematic diagram showing the state of the lower end of the self-standing bag.

Next, the present invention will be described in detail with reference to an embodiment, but the present invention should not be interpreted as being limited to these descriptions. Various modifications of the embodiment may be made as long as the effects of the present invention are achieved.

1 is a schematic front view showing an example of a self-supporting bag according to this embodiment. FIG. 2 is a schematic end view of line A-A in FIG. 1. As shown in FIG. 1 or FIG. 2, the self-supporting bag 1 according to this embodiment includes a body 10 having a body film 2 in a flat shape with a cylindrical shape with an upper end 12 and a lower end 11 open, and creases on the left edge 13 and the right edge 14, and a bottom gusset 20 having a flat bag-shaped bottom film 3 with an open edge 21 at the lower end inserted into the lower end of the body 10 with the open edge 21 facing downward. The body film 2 and the bottom film 3 are fixed by a bottom seal 30, and the bottom seal 30 has at least a first seal portion 31 in which the lower end of the bottom film 3 is bonded to the inner surface of the lower end of the body film 2 over the entire circumference of the bottom film 3. In this specification, top, bottom, left and right refer to the side where the bottom gusset 20 is attached as the bottom, the side opposite the side where the bottom gusset 20 is attached as the top, the left side as you face the drawing as the left, and the right side as you face the drawing as the right, when viewed in plan as in Figure 1, with either the front or back of the freestanding bag 1 in which the body film 2 and bottom film 3 are flattened.

The self-supporting bag 1 has a body 10 and a bottom gusset 20, and is a bag that can stand on its own by expanding the bottom gusset 20.

The body 10 is preferably substantially rectangular in plan view, with an upper end 12, a lower end 11, a left edge 13, and a right edge 14. In this specification, the word "substantially" before "shape" means an approximate outer shape without attention to detail, and includes not only the shape itself, but also various deformed shapes such as a shape in which at least one corner of the shape itself is rounded or at least one corner is removed, or a distorted shape. For example, "substantially rectangular shape" means a rectangular shape, a shape in which at least one corner of a rectangle is rounded or at least one corner is removed, or a deformed shape in which at least one side is slightly distorted. In this specification, the surface of the body 10 facing the storage space 15 is referred to as the inner surface of the body 10 or the inner surface of the body film 2, and the surface opposite the side facing the storage space 15 is sometimes referred to as the outer surface of the body 10 or the outer surface of the body film 2.

The body 10 is formed by flattening the body film 2 having a cylindrical shape, and the internal space of the cylindrical shape is the storage space 15 for the contents. Here, the flat shape refers to a state in which the inner wall surfaces of the opposing body films 2 are close to each other and the cross-sectional shape of the self-supporting bag 1 is elongated when there is no content in the storage space 15, as shown in FIG. 2. When the body film 2 is flattened, there is no heat seal on the left edge 13 and the right edge 14, but folds are formed. The cylindrical shape also includes a form with no seams in the circumferential direction (shown in FIG. 2) and a form with seams in the circumferential direction (not shown). The form with no seams in the circumferential direction as shown in FIG. 2 is, for example, a form in which an inflation-molded film is used as the body film 2. In addition, the form with a seam in the circumferential direction (not shown) may be, for example, a form in which a single film is used as the body film 2, both side edges of the single film are butted together without any gaps, and an adhesive film (not shown) is placed on the inner surface side of the film and heat sealed to form a backing, or an envelope-like form in which the inner surface of one side edge of a single film as the body film 2 is heat-sealed or adhesively bonded to the outer surface of the other side edge, or a palm-and-seat-like form in which the inner surfaces of both side edges of a single film as the body film 2 are heat-sealed or adhesively bonded to each other. In the form with a seam in the circumferential direction (not shown), it is preferable that the seam is provided offset from the portions that will become the left edge 13 and the right edge 14 when flattened.

The upper end 12 of the body 10 is shown in an open state as an example in FIG. 1, but it may be sealed with a fitting (not shown) or a sealing seal (not shown), or a spout (not shown) may be provided. Providing a spout at the upper end 12 of the body 10 makes it useful as a substitute for a plastic bottle. For example, from the perspective of environmental conservation, many municipalities require that the cap and the printed shrink label of a plastic bottle be separated from the bottle body before disposal. It takes time for consumers to dispose of the bottle, and there is a risk of injuring their nails or fingers when peeling off the shrink label. The self-supporting bag 1 according to this embodiment can be printed directly on the body 10, so there is no need to separate the label when disposing of the bag, and it can be disposed of without separating it from the spout. Therefore, it is not only easy to dispose of the bag in household garbage, but also contributes to reducing the work time at restaurants, and the cost of disposal and labor costs. Since the self-supporting bag 1 uses less resin than a plastic bottle, it can be crushed into small pieces after use, which can dramatically reduce the amount of garbage. For example, after the contents of the self-supporting bag 1 according to this embodiment have been emptied, the body of the bag can be folded from the bottom to the top where the spout is located with the cap removed, and when it has been folded down to the bottom end of the spout, the cap can be tightened, maintaining a reduced pressure inside the bag, so that the volume of the bag when discarded is about the size of a felt-tip pen. Furthermore, if the self-supporting bag 1 is washed after use, it can be reused in the same way as a plastic bottle, reducing the burden on the environment. The self-supporting bag 1 can be manufactured more cheaply than a plastic bottle, so the economic benefits are immeasurable.

The material of the body film 2 may be any of the following examples <1> to <29>, but is not particularly limited in this embodiment. Of these, the material of the body film 2 is preferably, for example, a polyethylene resin or a polypropylene resin. The body film 2 may include a porous base material such as paper.
<1> High density polyethylene (HDPE)
<2> Medium density polyethylene (MDPE)
<3> Low density polyethylene (LDPE)
<4> Polypropylene (PP)
<5> Polyvinylidene chloride (PVDC)
<6> Polyvinyl chloride (PVC)
<7> Polystyrene (PS)
<8> Polyvinyl acetate (PVAc)
<9> Polytetrafluoroethylene (PTFE)
<10> ABS resin (acrylonitrile butadiene styrene resin)
<11> AS resin (SAN)
<12> Acrylic resin (PMMA)
<13> Polyamide (PA) / Product name Nylon <14> Polyacetal (POM)
<15> Polycarbonate (PC)
<16> Modified polyphenylene ether (m-PPE, modified PPE, PPO)
<17> Polybutylene terephthalate (PBT)
<18> Polyethylene terephthalate (PET)
<19> Cyclic polyolefin (COP)
<20> Polyphenylene sulfide (PPS)
<21> Polysulfone (PSF)
<22> Polyethersulfone (PES)
<23> Amorphous polyarylate (PAR)
<24> Liquid crystal polymer (LCP)
<25> Polyether ether ketone (PEEK)
<26> Thermoplastic polyimide (PI)
<27> Polyamideimide (PAI)
<28> Thermoplastic polyurethane (TPU)
<29> Fluorine resin (PTFE)

The body film 2 may be a single layer film or a laminated film. The thickness of the body film 2 is not particularly limited, but is preferably 50 to 250 μm, and more preferably 80 to 200 μm.

In the self-supporting bag 1 according to this embodiment, the material of the body film 2 is a laminated film in which PE with different melting points is arranged on the front and back, and it is preferable that the melting point of the PE on the inside of the self-supporting bag 1 is lower than the melting point of the PE on the outside of the self-supporting bag 1. This allows the formation of the bottom seal 30, the sealing of the upper end 12 of the body 10, or the thermal bonding of the spout to be performed more efficiently. The body film 2 is preferably a layered structure in which high-melting point PE and low-melting point PE are arranged in that order from the outside, and more preferably a co-extruded film of high-melting point PE and low-melting point PE. The high-melting point PE is a polyethylene with a relatively high melting point. The melting point of the high-melting point PE is not particularly limited, but is preferably 90 to 130°C, and more preferably 100 to 120°C. The low-melting point PE is a polyethylene with a melting point lower than that of the high-melting point PE. The melting point of the low-melting point PE is not particularly limited, but is preferably 70 to 100°C, and more preferably 80 to 90°C. The difference in melting point between the high-melting point PE and the low-melting point PE is preferably 10 to 50°C, and more preferably 20 to 40°C.

The bottom gusset 20 closes the lower end 11 of the body 10. The bottom gusset 20 has a bag shape with one side open. When there is no content in the storage space 15, the bottom gusset 20 is folded and flattened inside the body 10, and the self-supporting bag 1 is flat as a whole. When content is stored in the storage space 15, the bottom gusset 20 unfolds and the self-supporting bag 1 can stably stand on its own. In this specification, when the bottom gusset 20 is in the shape of a flat bag, the outer surface is referred to as the outer surface of the bottom gusset 20 or the outer surface of the bottom film 3, and the inner surface is sometimes referred to as the inner surface of the bottom gusset 20 or the inner surface of the bottom film 3.

The bottom gusset 20 is made of a bottom film 3 that has a flat bag shape with one end open. The planar shape of the bottom gusset 20 is not particularly limited, but may be an approximately square, approximately triangular, approximately pentagonal, approximately semicircular, or approximately elliptical shape, but is preferably an approximately square shape.

The material of the bottom film 3 can be any of the materials listed as the material of the body film 2. The material of the bottom film 3 may be the same as or different from the material of the body film 2. The thickness of the bottom film 3 is preferably thinner than the thickness of the body film 2. This makes it easier to open the bottom gusset 20. For example, the thickness of the bottom film 3 is preferably 25 to 200 μm, and more preferably 40 to 180 μm.

In the self-supporting bag 1 according to this embodiment, the material of the bottom film 3 is a laminated film in which PE with different melting points is arranged on the front and back, and it is preferable that the melting point of the PE on the outside (the side of the body film 2) of the laminated film is lower than the melting point of the PE on the inside (the side opposite the body film 2). This prevents the insides of the bottom film 3 from adhering to each other when the bottom seal 30 is formed, so that the self-supporting bag 1 can be efficiently manufactured. It is more preferable that the bottom film 3 has a layered structure in which low-melting point PE and high-melting point PE are arranged in that order from the outside, and it is more preferable that the bottom film 3 is a co-extruded film of low-melting point PE and high-melting point PE. The melting point of the low-melting point PE is not particularly limited, but is preferably 70 to 100°C, more preferably 80 to 90°C. The melting point of the high-melting point PE is not particularly limited, but is preferably 90 to 130°C, more preferably 100 to 120°C. The melting point difference between the high-melting point PE and the low-melting point PE is preferably 10 to 50°C, more preferably 20 to 40°C. By making the bottom film 3 have a layered structure with a difference in melting point between the front and back as described above, when forming the bottom seal 30, it is possible to only bond the inner surface of the body film 2 to the outer surface of the bottom film 3, without bonding the inner surfaces of the bottom film 3 together.

In the self-supporting bag 1 according to this embodiment, the bottom gusset 20 preferably has an open edge 21, an upper end closed edge 22 opposite the open edge 21, a left closed edge 23 connecting the left end of the open edge 21 and the left end of the upper end closed edge 22, and a right closed edge 24 connecting the right end of the open edge 21 and the right end of the upper end closed edge 22. This improves the yield of the bottom film during manufacturing and allows efficient production, thereby reducing manufacturing costs. The open edge 21 is a portion where the ends of the opposing bottom films 3 are not bonded to each other, and is the lower end of the self-supporting bag 1. The upper end closed edge 22 may be a portion where the ends of the opposing bottom films 3 are bonded to each other (as shown in FIG. 1) or may be a fold of the bottom film 3 (as shown in FIG. 5), and is a portion facing the storage space 15. The left closed edge 23 may be a fold in the bottom film 3 (as shown in FIG. 1) or a portion where the ends of opposing bottom films 3 are bonded together (as shown in FIG. 5), and is the portion facing the inner wall of the left edge 13 of the body 10. The right closed edge 24 may be a fold in the bottom film 3 (as shown in FIG. 1) or a portion where the ends of opposing bottom films 3 are bonded together (as shown in FIG. 5), and is the portion facing the inner wall of the right edge 14 of the body 10.

3 is a schematic diagram showing a first example of the bottom film 3. FIG. 4 is a schematic diagram showing a second example of the bottom film 3. In the self-supporting bag 1 according to this embodiment, the bottom film 3 (3A, 3B) has a tubular shape with both ends open as shown in FIG. 3 or FIG. 4, the open edge 21 is a portion where the bottom films 3 (3A, 3B) facing each other at one end of the tubular shape of the bottom film 3 (3A, 3B) are in a non-adhesive state, the upper end closed edge 22 is a portion where the bottom films 3 (3A, 3B) facing each other at the other end of the tubular shape of the bottom film 3 (3A, 3B) are bonded and closed, and the left closed edge 23 and the right closed edge 24 are preferably folds formed by flattening the tubular shape of the bottom film 3 (3A, 3B). For example, the bottom film 3 (3A, 3B) can be manufactured through a simple process in which a roll of cylindrical film is prepared in advance, and the film is unrolled while being heat sealed and slit at predetermined intervals, thereby reducing manufacturing costs.

In the self-supporting bag 1 according to the present embodiment, the bottom film 3 is a tubular film 3A with no seams in the circumferential direction as shown in FIG. 3, or a sheet-like film 3B as shown in FIG. 4, and includes a form in which the sheet-like film 3B is attached to the back to form a cylindrical shape. The method for manufacturing the tubular film 3A with no seams in the circumferential direction as shown in FIG. 3 can be a known method, and is not particularly limited, but it can be manufactured by inflation molding, for example. The method for manufacturing the sheet-like film 3B as shown in FIG. 4 can be a known method, and is not particularly limited, but it can be manufactured by extrusion molding, for example. The back attachment 25 may be a form in which the inner surfaces of both ends of one film 3B are attached to each other, a form in which the inner surface of one side end of one film 3B is attached to the outer surface of the other side end of one film 3B, or a form in which both ends of one film 3B are butted together without any gaps and heat-sealed with an adhesive film (not shown) superimposed on the inner surface side.

Figure 5 is a schematic diagram showing a third example of the bottom film. As shown in Figure 5, the bottom film 3 may be a single sheet-like film 3C, with the fold of the single sheet-like film 3C folded in half forming an upper closed edge 22, the edge opposite the fold where the inner surfaces of the sheet-like film 3C are not bonded together forming an open edge 21, and the edges extending from both ends of the fold where the inner surfaces of the sheet-like film 3C are bonded together to close the fold forming a left closed edge 23 and a right closed edge 24.

Figure 6 is a schematic diagram showing a fourth example of the bottom film. As shown in Figure 6, the bottom film 3 may be two sheet-like films 3D, and the two sheet-like films 3D may be overlapped to form an open edge 21 at one edge of the periphery where the inner surfaces of the sheet-like films 3D are not bonded together, and the remaining edges of the periphery where the inner surfaces of the sheet-like films 3D are bonded together and closed to form an upper closed edge 22, a left closed edge 23, and a right closed edge 24, respectively.

Figure 7 is a schematic diagram showing a fifth example of the bottom film. The bottom film 3 may be a single sheet-like film 3E, and the fold of the single sheet-like film 3E folded in half may be either the left closed edge 23 or the right closed edge 24 (the right closed edge 24 in Figure 7), the part where the inner surfaces of the bottom film are bonded together at the edge facing the fold may be either the left closed edge 23 or the right closed edge 24 (the left closed edge 23 in Figure 7), the part where the inner surfaces of the sheet-like film 3E are bonded together at the edge extending from one end of the fold may be the upper closed edge 22, and the part where the inner surfaces of the sheet-like film 3E are not bonded together at the edge extending from the other end of the fold may be the open edge 21.

In Figures 3 to 7, the bottom film 3 (3A to 3E) is shown in a form in which the length of the open edge 21 is the same as the length of the upper end closed edge 22, but the present invention is not limited to this, and the length of the open edge 21 may be shorter than the length of the upper end closed edge 22. By making the open edge 21 shorter than the upper end closed edge 22, it is possible to prevent the bottom gusset 20 from protruding from the body portion 10.

In FIG. 1, as an example, the self-supporting bag 1 is shown using the bottom film 3A shown in FIG. 3 as the bottom gusset 20, but the present invention is not limited to this. Instead of the bottom gusset 20 using the bottom film 3A shown in FIG. 3, the self-supporting bag 1 may have a bottom gusset using, for example, the bottom films 3B, 3C, 3D, and 3E shown in FIG. 4 to FIG. 7.

The bottom seal 30 is a portion where the inner surface of the body film 2 and the outer surface of the bottom film 3 facing each other are partially bonded together when the bottom film 3 is inserted into the lower end of the body film 2. From the viewpoint of production efficiency, the bottom seal 30 is preferably bonded by heat sealing, but it may also be bonded using a secondary material such as an adhesive.

The first seal portion 31 is a portion where the outer surface of the bottom film 3 near the open edge 21 and the outer surface of the body film 2 near the lower end 11 are bonded together.

8 is a schematic partial enlarged view of area B surrounded by a dashed line in FIG. 1. In FIG. 8, the lower left portion of the self-supporting bag 1 is shown as a representative example, but the lower right portion of the self-supporting bag 1 may be formed symmetrically with the lower left portion. The self-supporting bag 1 according to this embodiment includes a form in which there is a gap 40 between the left and right side edges 13, 14 of the body 10 and the left and right closed edges 23, 24 of the bottom gusset 20 (shown in FIG. 1 and FIG. 8), and a form in which there is no gap 40 between the left and right side edges 13, 14 of the body 10 and the left and right closed edges 23, 24 of the bottom gusset 20 (not shown). As shown in FIG. 8, the self-supporting bag according to this embodiment has a gap 40 between the inner wall at the left edge 13 of the body 10 and the bottom gusset 20, or between the inner wall at the right edge 14 (shown in FIG. 1) of the body 10 and the bottom gusset 20, or both, and the bottom seal 30 preferably further has a second seal portion 32 in which the inner surfaces of the body film 2 are bonded together at the gap 40. By having the gap 40, the bottom film 3 can be more easily inserted into the lower end of the body film 2. This can further increase production efficiency.

The gap 40 may be provided only between the inner wall and the bottom gusset 20 at the left edge 13 of the body 10, or only between the inner wall and the bottom gusset 20 at the right edge 14 of the body 10 (shown in FIG. 1), or may be provided both between the inner wall and the bottom gusset 20 at the left edge 13 of the body 10 and between the inner wall and the bottom gusset 20 at the right edge 14 of the body 10 (shown in FIG. 1). The spacing of the gap 40 is not particularly limited, but is preferably 0.1 to 1.0 mm, and more preferably 0.4 to 0.7 mm.

The second sealed portion 32 is a portion where the inner surfaces of the body film 2 are bonded together at the gap 40. The second sealed portion 32 is continuous with the first sealed portion 31, and can close the bottom end 11 of the body 10 even if there is a gap 40 between the left and right side edges 13, 14 of the body 10 and the left and right closing edges 23, 24 of the bottom gusset 20.

As shown in FIG. 8, the self-supporting bag 1 according to this embodiment preferably further includes a reinforcing seal portion 33 in the region spanning the first seal portion 31 and the second seal portion 32. The reinforcing seal portion 33 can prevent pinholes from occurring at the boundary between the first seal portion 31 and the second seal portion 32.

9 is a schematic front view of an example of a self-supporting bag according to this embodiment, showing a form having an inclined seal portion. In the self-supporting bag 1 according to this embodiment, the bottom seal 30 has a left inclined seal portion 36 that extends diagonally between the open edge 21 and the left closed edge 23, and a right inclined seal portion 37 that extends diagonally between the open edge 21 and the right closed edge 24, and it is preferable that the left inclined seal portion 36 and the right inclined seal portion 37 are portions where the inner surfaces of the body film 2 facing each other and the bottom film 3 are bonded. By providing the left inclined seal portion 36 and the right inclined seal portion 37, the bottom gusset 20 can be held in the body 10, so that it can stand on its own more stably. The bottom seal 30 may further have a left vertical seal 38 that connects the upper end of the left inclined seal portion 36 to the left end of the first seal portion 31, and may further have a right vertical seal 39 that connects the upper end of the right inclined seal portion 37 to the right end of the first seal portion 31. The left inclined seal portion 36 and the right inclined seal portion 37 do not form an edge because they do not include an adhesive portion between the inner surfaces of the body film 2. In FIG. 8, the left inclined seal portion 36 and the right inclined seal portion 37 are linear, and the left inclined seal portion 36, the first seal portion 31, and the right inclined seal portion 37 are connected to form an inverted trapezoid shape, but the present invention is not limited to this. For example, the left inclined seal portion 36 and the right inclined seal portion 37 may be arc-shaped with a protrusion on the outside, and the left inclined seal portion 36, the first seal portion 31, and the right inclined seal portion 37 may be connected to form an arc shape (not shown).

10 is a schematic front view of an example of a self-supporting bag according to this embodiment, showing a form having a spot seal portion. In the self-supporting bag 1 according to this embodiment, the bottom gusset 20 has a left corner portion 26 formed by the left end of the top closed edge 22 and the top end of the left closed edge 23, and a right corner portion 27 formed by the right end of the top closed edge 22 and the top end of the right closed edge 24, and the bottom seal 30 preferably has a point seal portion 35 that partially bonds the inner surface of the body film 2 and the bottom film 3 facing each other at the left corner portion 26 and the right corner portion 27. By providing the point seal portion 35, the bottom gusset 20 can be held inside the body portion 10, so that it can stand on its own more stably. The left corner portion 26 is an area including the apex formed by the top closed edge 22 and the left closed edge 23 and the outer surface of the body portion 10 around the apex. The right corner 27 is an area including the apex formed by the upper end closed edge 22 and the right closed edge 24 and the outer surface of the body 10 around the apex. The point seal 35 is also called a spot seal, and is a part where a part of the inner surface of the body film 2 and a part of the outer surface of the bottom film 3 facing each other are bonded together. The shape of the point seal 35 is shown as an approximately circular shape in FIG. 10 as an example, but the present invention is not limited to this, and may be, for example, an approximately rectangular shape, an approximately square shape, an approximately triangular shape, an approximately trapezoidal shape, an approximately elliptical shape, or other modified shape.

Figure 11 is a diagram for explaining the manufacturing method of the self-supporting bag according to this embodiment, where (a) is a diagram explaining steps 1 and 2, (b) is a diagram explaining step 3, (c) is a diagram explaining step 4, and (d) is a diagram explaining step 5, and (e) is a schematic diagram of the self-supporting bag after step 5. The method for manufacturing a self-supporting bag 1 according to this embodiment includes a body 10 made of a body film 2 and a bottom gusset 20 made of a bottom film 3, and the body film 2 and the bottom film 3 are joined with a bottom seal 30. The method includes the steps of: preparing a cylindrical film with both ends open as the body film 2 as shown in FIG. 11(a); forming the bottom film 3 into a flat bag shape with an open edge 21 at one end as shown in FIG. 11(a); arranging the bottom film 3 inside the body film 2 as shown in FIG. 11(b); heat-sealing an area including the overlapping portion of the body film 2 and the bottom film in the arrangement state of step 3 as shown in FIG. 11(c); and cutting across the heat-sealed portion formed in step 4 to form a bottom seal 30 as shown in FIG. 11(d).

Step 1 is a step of forming the body film 2. Although there is no particular limitation to step 1, it is preferable that the method be, for example, a method of preparing a roll of tubular film formed by inflation molding, and slitting the tubular film at a predetermined interval while unwinding it, thereby forming the body film 2 having a cylindrical shape with both ends open. This makes it possible to form the body 10 without seams in the circumferential direction. Step 1 may also be a method of forming a body film 2 having a cylindrical shape with both ends open, for example, by forming a sheet-like film into a cylindrical shape by spine pasting, envelope pasting, or hem pasting while unwinding it, and slitting it at a predetermined interval.

Step 2 is a step of forming the bottom film 3. Step 2 is not particularly limited, but is preferably a method of preparing a roll of inflation-molded tubular film, heat-sealing and slitting the tubular film at a predetermined interval while unwinding it, to form a flat bag-shaped bottom film 3 (3A) having an open edge 21 at one end. This results in a bottom film 3 (3A) as shown in FIG. 3, and the bottom film 3 can be made to a stable and constant width, so that when the bottom film 3 is inserted into the body film 2 in the next step 3, it is easy to manage the width of the gap 40 (shown in FIG. 8) between the left and right side edges 13, 14 of the body 10 and the left and right closed edges 23, 24 of the bottom gusset 20. In addition, the yield is improved and production can be made efficient, so that manufacturing costs can be reduced. Alternatively, step 2 may be a method in which, for example, a sheet-like film is unwound and formed into a cylindrical shape by back-pasting, envelope-pasting, or flaps-pasting, and then heat-sealed and slit at a predetermined interval to form a flat bag-shaped bottom film 3 (3B) having an open edge 21 at one end. This results in a bottom film 3 (3B) as shown in FIG. 4. Alternatively, step 2 may be a method in which, for example, a sheet film of a predetermined size is folded in half or two sheets are stacked, and the open edges except for one edge are glued together to close the bottom film 3 (3C, 3D, 3E) having a flat bag-shaped bottom film 21 at one end. This results in a bottom film 3 (3C, 3D, 3E) as shown in FIGS. 5 to 7.

Step 3 is a step of inserting the bottom film 3 into the body film 2. In step 3, the open edge 21 may be positioned so that it is more inward than one end of the body film 2 (not shown), or so that it coincides with one end of the body film 2 (as shown in FIG. 11(b)), or so that it projects outward from one end of the body film 2 (not shown). Of these, it is more preferable to position the open edge 21 so that it coincides with one end of the body film 2 or so that it projects outward from one end of the body film 2.

Step 4 is a step of fixing the bottom film 3 to the body film 2. In step 4, in the state of arrangement in step 3, the body film 2 may be heat-sealed above one end (not shown), or the area including one end of the body film 2 may be heat-sealed (shown in FIG. 11(c)). The heat sealing may be, for example, heat sealing, ultrasonic sealing, high frequency sealing, spot sealing, impulse sealer, or laser bonding. It is preferable that step 4a includes heat sealing along one end of the body film 2 and the open edge 21 of the bottom film 3, and after step 4a, heat sealing an area including the gap 40 (shown in FIG. 8) between the left and right side edges 13, 14 of the body 10 and the left and right closed edges 23, 24 of the bottom gusset 20. Step 4 may also include step 4c of forming the left inclined seal portion 36 (shown in FIG. 9) and the right inclined seal portion 37 (shown in FIG. 9) or step 4d of forming the point seal portion 35 (shown in FIG. 10). Step 4c or step 4d may be performed before or after step 4a, or may be performed simultaneously with step 4a. By forming the bottom film 3 into a layered structure in which PE with a melting point difference is arranged on the front and back sides as described above, in step 4, it is possible to only bond the inner surface of the body film 2 to the outer surface of the bottom film 3 without bonding the inner surfaces of the bottom film 3 to each other. If the bottom film 3 is, for example, a monolayer film with no melting point difference on the front and back sides, in step 4, it is possible to only bond the inner surface of the body film 2 to the outer surface of the bottom film 3 without bonding the inner surfaces of the bottom film 3 to each other by interposing a heat-resistant adhesive middle plate or a heat-resistant adhesive sheet between the inner surfaces of the bottom film 3. The heat-resistant adhesive middle plate or the heat-resistant adhesive sheet is, for example, a plate-shaped member or a sheet-shaped member made of a high-melting point material such as nylon or silicone.

Step 5 is a step of cutting the heat seal formed in step 4 at an appropriate position to make it self-supporting. FIG. 11(e) shows an example of a shape cut at the position of the two-dot chain line C in FIG. 11(d). In order to improve the self-supporting property of the self-supporting bag 1, the fixing position of the bottom film 3 to the body film 2 is important. That is, the lower end of the body film 2 and the open edge 21 of the bottom film 3 coincide with each other, and the coincident lower end of the body film 2 and the open edge 21 of the bottom film 3 are bonded over the entire circumference, so that the bonded part between the lower end of the body film 2 and the open edge 21 of the bottom film 3, which has high rigidity, is placed on the ground surface of the self-supporting bag 1, and the self-supporting bag 1 can stand on its own stably. However, if the open edge 21 is positioned so as to be inside one end of the body film 2 in step 3, there is a problem that if the area including the lower side of the open edge 21 is heat-sealed in step 4, the inner surfaces of the body film 2 are heat-bonded to each other, and the bottom gusset 20 cannot be opened. Therefore, by providing step 5, the heat-bonded portion between the inner surfaces of the body film 2 is cut and removed, and the bottom gusset 20 can be opened. Furthermore, if the open edge 21 is made to coincide with one end of the body film 2 in step 3, when the region including the upper side of the open edge 21 is heat-sealed in step 4, a portion where the body film 2 and the bottom film 3 are not bonded to each other is formed below the open edge 21, and wrinkles may occur. Therefore, by providing step 5, the non-bonded portion between the body film 2 and the bottom film 3 is cut and removed, and a self-standing bag 1 with a good appearance can be obtained. Furthermore, if the open edge 21 is arranged so as to protrude from one end of the body film 2 to the outside in step 3, a portion of the bottom film 3 protruding from one end of the body film 2 is formed in the bag that has undergone step 4. At this time, the protruding portion of the bottom film 3 is located at the lowest end of the bag and is to come into contact with the ground surface when the bag is made to stand on its own, but the strength of the bottom film 3 alone is insufficient, and the self-standing may not be stable. Therefore, by providing step 5, the protruding portion of the bottom film 3 is cut off and removed, resulting in a self-supporting bag 1 with stable self-supporting ability. As described above, by providing step 5, there is no need to strictly control the positional relationship between the body film 2 and the bottom film 3 and the heat sealing position in steps 3 and 4, and therefore production efficiency can be improved.

In a typical self-supporting bag such as that in Patent Document 1, the left and right side edges of the body are provided with side seals that bond the inner surfaces of the body film together in the entire vertical direction of the body. In addition, in an attempt to make the side seals as short as possible, there is a technique for manufacturing a self-supporting bag 90 by inserting a bottom film 92 folded in half into a body film 91 that is formed into a cylindrical shape and has no side seals, as shown in Figures 12(a) and (b). However, in order to ensure that the bottom film 92 can be inserted into the body film 91, the width of the bottom film 92 is configured to be narrower than the width of the body film 91, and the fixation of the body film 91 and the bottom film 92 requires, as shown in Figure 12(b), a bottom seal 93 that fixes the bottom end of the bottom film 92 to the bottom end of the body film 91, as well as a side seal 94 that closes the left and right sides of the bottom film 92 that are folded in half and fixes the bottom film 92 to the body film 91. In addition, if the width of the bottom film 92 is made to be approximately the same as that of the body film 91 in order to eliminate the side seal 94, the manufacturing precision must be increased, and it is difficult to secure machinery, personnel, and time. As described above, the conventional self-supporting bag 90 requires a side seal including the adhesive portion between the inner surfaces of the body film 91 in order to improve production efficiency, which results in sharp edges and a poor feel to the touch. On the other hand, the self-supporting bag 1 according to this embodiment has no side seals on the left and right side edges 13, 14 of the body 10, and creases are formed, as shown in FIG. 1. Furthermore, even if a gap 40 is provided between the body film 2 and the bottom film 3 in order to improve production efficiency, the adhesive portion between the inner surfaces of the body film 2 that can become an edge can be limited to the second seal portion 32 at the lower end of the self-supporting bag 1, and there is almost no effect on the fingers when the self-supporting bag 1 is held. In this way, the self-supporting bag 1 according to this embodiment is edgeless, and the side seal does not come into contact with the hand even when the body 10 is held by hand, so there is no discomfort.

1 Self-supporting bag 2 Body film 3 (3A, 3B, 3C, 3D, 3E) Bottom film 10 Body 11 Lower end 12 Upper end 13 Left side edge 14 Right side edge 15 Storage space 20 Bottom gusset 21 Open edge 22 Upper end closed edge 23 Left side closed edge 24 Right side closed edge 25 Back lining 26 Left side corner 27 Right side corner 30 Bottom seal 31 First seal portion 32 Second seal portion 33 Reinforcement seal portion 35 Point seal portion 36 Left side inclined seal portion 37 Right side inclined seal portion 38 Left vertical seal 39 Right vertical seal 40 Gap 90 Self-supporting bag 91 Body film 92 Bottom film 93 Bottom end seal 94 Side seal

Claims (8)

A body portion having a cylindrical shape with an open upper end and a closed lower end, the body portion being flattened and having folds on the left and right edges;
A bottom gusset is provided, the bottom film having a flat bag shape with an open side at the lower end, the open side being inserted into the lower end of the body portion with the open side facing downward;
The body film and the bottom film are fixed together by a bottom seal,
The bottom seal has at least a first seal portion in which a lower end portion of the bottom film is adhered to an inner surface of a lower end portion of the body film around the entire circumference of the bottom film,
the bottom gusset has the open side, an upper closed side opposite to the open side, a left closed side connecting a left end of the open side and a left end of the upper closed side, and a right closed side connecting a right end of the open side and a right end of the upper closed side,
The upper end closing edge is an adhesive portion between the ends of the bottom film facing each other, or a fold of the bottom film;
A self-supporting bag characterized in that the left closed edge and the right closed edge are both adhesive joints between opposite ends of the bottom film, or either one of the left closed edge and the right closed edge is an adhesive joint between opposite ends of the bottom film, and the other of the left closed edge and the right closed edge is a fold of the bottom film. The bottom film is a single sheet-like film,
the upper end closed side is the fold line, and the fold line is a fold line formed by folding the single sheet-like film in half,
The open side is an edge opposite to the fold line, where the inner surfaces of the sheet-like film are not bonded to each other,
The self-supporting bag according to claim 1, characterized in that the left closed edge and the right closed edge are both adhesive portions, and the adhesive portions are portions where the inner surfaces of the sheet-like film are adhered to each other at both edges extending from both ends of the fold. The bottom film is two sheet-like films,
The open side is a portion where the inner surfaces of the two sheet-like films overlap each other at one edge of the peripheral edges, and are not bonded to each other;
The self-supporting bag according to claim 1, characterized in that the upper end closed edge, the left side closed edge and the right side closed edge are all adhesive portions, and the adhesive portions are portions where the inner surfaces of the two sheet-like films overlapped by the remaining edges of the periphery are adhered to each other. The bottom film is a single sheet-like film,
Either the left closed edge or the right closed edge is the fold line, and the fold line is a fold line formed by folding the single sheet-like film in half,
the other of the left closed edge and the right closed edge is the adhesive portion, and the adhesive portion is a portion where the inner surfaces of the sheet-like film are adhered to each other at an edge opposite to the fold,
the upper end closed edge is the adhesive portion, and the adhesive portion is a portion where the inner surfaces of the sheet-like film are adhered to each other at an edge extending from one end of the fold,
2. The self-supporting bag according to claim 1, wherein the open side is an edge extending from the other end of the fold where the inner surfaces of the sheet-like film are not bonded to each other. The self-supporting bag has a gap between an inner wall at the left edge of the body and the bottom gusset, or between an inner wall at the right edge of the body and the bottom gusset, or both, and
5. The self-supporting bag according to claim 1, wherein the bottom seal further comprises a second seal portion in which the inner surfaces of the body film are bonded to each other in the gap. The self-supporting bag according to claim 5, further comprising a reinforcing seal portion in an area spanning the first seal portion and the second seal portion. the bottom seal has a left inclined seal portion extending obliquely between the open edge and the left closed edge, and a right inclined seal portion extending obliquely between the open edge and the right closed edge,
5. The self-supporting bag according to claim 1, wherein the left inclined seal portion and the right inclined seal portion are portions where the inner surfaces of the body film and the bottom film facing each other are bonded to each other. the bottom gusset has a left corner portion formed by the left end of the upper closed edge and the upper end of the left closed edge, and a right corner portion formed by the right end of the upper closed edge and the upper end of the right closed edge,
The self-supporting bag according to any one of claims 1 to 4, characterized in that the bottom seal has a point seal portion at the left corner portion and the right corner portion, which partially bonds the inner surface of the body film and the bottom film facing each other.