JP3952145B2 - Self-supporting bag and its manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a self-supporting bag provided with a closure portion, and more particularly, to a self-supporting bag that is flexible and excellent in self-supporting property and excellent in attachment strength of the closure portion.
[0002]
[Prior art and problems to be solved by the invention]
Conventionally, self-supporting bags for fluids such as liquids are mainly used for refilling and do not place much weight on self-supporting. For example, if the contents are reduced to about 1/3 or less, the upper part of the bag bends and becomes self-supporting. It had no function as a bag. In particular, the self-supporting bag for fluid may be provided with a closure for pouring out the contents, and in such a case, the upper part becomes heavy, and the lack of self-supporting property is remarkable. It was. In addition, the conventional free-standing bag with a closure part is joined by hot welding the peripheral part of the bag body, and the closure part is molded separately, and the closure part is manually inserted between the sheets forming the bag body. And the closure part was attached by heat-welding with the sheet | seat inner surface. Such a manual operation not only affects the mass productivity, but also there is a fear that the thermal strength between the closure part and the sheet becomes insufficient, and the strength of the bag body becomes insufficient. On the other hand, the molded container, as a matter of course, has sufficient self-supporting property, but it cannot be reduced by being folded at the time of disposal.
[0003]
The present invention has been made in view of the above circumstances, and when used, the function as a free-standing bag is maintained until the contents are no longer used, and when discarded, it can be folded to reduce the capacity, and the attachment strength of the closure part can be reduced. It is another object of the present invention to provide a self-supporting bag excellent in manufacturing and a method for manufacturing a self-supporting bag suitable for manufacturing the self-supporting bag.
[0004]
[Means for Solving the Problems]
That is, the present invention is a self-supporting bag having a closure portion at the top of a bag body, wherein both side edges and upper edge of the bag body are made of a thermoplastic resin covering the outer surfaces of these edges. And the closure part is integrally formed with the edge joint part. Here, it is more preferable that the edge joint portion of the bag body and the closure portion are formed by injection molding.
[0005]
The present invention also relates to a method for manufacturing the self-supporting bag, wherein when the edge joint portion of the bag body is formed, a cavity is formed at the edge of the bag body, and a thermoplastic resin is injected into the cavity. Then, an edge joining portion is formed by joining the edges of the bag body, and a self-standing bag manufacturing method is provided. Here, when forming the edge joint portion of the bag body, a die-slip injection method is used to form a cavity that is substantially half of the edge joint portion on one side of the edge of the bag body, A thermoplastic resin is injected into the cavity to mold a substantially halved body of the edge joint, and then a cavity is formed on the other surface side of the edge of the bag body to form the remaining shape of the edge joint. It is more preferable to form the edge joint part by injecting the thermoplastic resin into the mold and molding the remaining part of the edge joint part and joining the edge of the bag body.
[0006]
That is, in the self-supporting bag of the present invention, the upper edge and both side edges of the bag body are joined by the edge joining portion made of a thermoplastic resin covering the outer surfaces of these edges, so that the edge joining of each side edge is performed. The part becomes a so-called rib of the bag body and functions as a bag support, improving the bag body's independence, and even if it has a closure on the top of the bag body, it will have enough independence until the contents are gone Can be maintained. And since the closure part is integrally molded with the said edge joint part, it becomes the thing excellent also in the attachment strength of the closure part.
[0007]
Here, if the edge joint part of the bag body and the closure part are formed by injection molding, the edge joint part can be easily and reliably formed by, for example, a die slide injection method, and at the same time the closure. Since the parts can be integrally molded, it is more preferable.
[0008]
In the manufacturing method of the self-standing bag of the present invention, when forming the edge joint portion of the bag body, a cavity is formed in the edge of the bag body, and a thermoplastic resin is injected into the cavity to inject the bag body. It is a manufacturing method of the self-supporting bag characterized by forming an edge joined part by joining an edge. For example, when forming the edge joint portion of the bag body of the self-supporting bag, a cavity that is substantially halved of the edge joint portion is formed on one surface side of the edge of the bag body by a die slide injection method. Then, a thermoplastic resin is injected into the cavity to mold a substantially halved portion of the edge joint portion, and then a cavity is formed on the other side of the remaining shape of the edge joint portion, and the thermoplastic resin is placed in the cavity. It is a manufacturing method which forms an edge joint part by injecting and shape | molding the remainder of an edge joint part, and joining the edge of the said bag main body. By adopting such a method, for example, by injection molding performed in one step, the thermoplastic resin is injected so as to cover the outer surface of the end portion of the bag body placed in the mold in a state where the sheets overlap each other. Compared with the case where the edge joint portion is formed, when the outer surface of the edge of the bag body is covered with the thermoplastic resin, the edge of the bag body can be reliably disposed at the resin center (joint center). Therefore, it is preferable because the edge of the bag body can be joined more easily and reliably.
[0009]
【The invention's effect】
Since the self-supporting bag of the present invention is flexible and excellent in self-supporting, when used, it functions as a packaging bag having self-supporting properties and satisfies the self-supporting properties until there is no content item even if it has a closure part. After use, it can be rounded to a small capacity and discarded, and the attachment strength of the closure is also excellent. Therefore, the self-supporting bag of the present invention is easy to use at the time of use, can be easily reduced in volume when discarded after use, and is suitable for environmental protection. Moreover, according to the method for manufacturing a self-supporting bag of the present invention, a self-supporting bag having the above-described characteristics and particularly excellent in the bonding strength of the bag main body can be manufactured easily and reliably.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to the drawings. 1 and 2 illustrate an example of the configuration of the self-supporting bag of the present invention. FIG. 1 is a schematic perspective view showing a state where the self-supporting bag 1 is inflated. FIG. It is a schematic front view which shows the state folded. The self-supporting bag 1 includes a closure portion 3 at the upper end portion of the bag body 2 and is folded so that the lower side of the long film constituting the bag body 2 is folded in four. A bottom surface 2c is formed by joining the upper edge 2b to the other edge 2a.
[0011]
The bag body 2 is a single layer or multilayer film. These films do not necessarily have heat-welding properties as in the case of conventional films, but when formed into a bag, it is preferable that the film surface on the outer surface side adheres well to the resin to be injected. The multilayer film is a co-extruded film, a laminate film, etc., and in order to give a necessary function to a stretched or unstretched polyolefin, nylon, polyester film or resin layer, for example, a gas barrier layer (EVOH, saran, ceramic vapor deposition, etc.) A co-extrusion type or a laminate type film thereof is preferably used.
[0012]
As the thickness of the film, 20 to 900 μm is applied, and a thick film is suitable from the standpoint of self-supporting property, but even if it is a thin film from flexibility and light weight, by providing a side edge joint portion, Independence can be secured. In view of moldability and handleability, a preferable thickness is preferably 100 to 200 μm. The film is not limited to the one made of synthetic resin, and may be a single layer product or a laminate product of paper or metal foil.
[0013]
The shape and size of the closure part 3 are not particularly limited, and can be any shape and size according to the purpose of use of the packaging bag. Here, normally, the self-supporting bag with a closure part is manufactured by inserting the closure member into the upper end of the self-supporting bag by hand or by another operation using an automatic insertion machine and heat-sealing. In the case of a thick material, it is difficult to securely bond both ends of the closure member, and it is often difficult to perform the welding operation. However, in the present invention, since it is injection-molded integrally with the edge joining portion 4 as will be described later, there is no such difficulty.
[0014]
The edge joining portion 4 is formed by integral molding with the closure portion 3 simultaneously by injection molding, or the closure portion 3 is first molded and molded integrally in a mold. There is no particular limitation as long as it is a resin that can be injection-molded and can join the edges of the bag body 2, but it is a general-purpose resin such as polyethylene, polypropylene resin, and injectable plastics such as nylon, polyester, various engineering Blends or copolymer resins of resins and elastomers can also be used.
[0015]
The edge joint part 4 is a shape along the one side edge 2a to the upper edge 2b to the other edge 2a of the bag body 2 made of a resin film that is molded in advance to have a predetermined self-standing bag shape, The width and thickness are not particularly limited, but the width (arrow w in FIG. 1) is 1 to 20 mm, particularly 5 to 10 mm, and the thickness (arrow d in FIG. 1) is 1 to 10 mm, particularly 2 to 2. It is preferable that the thickness is 5 mm. If the width is too narrow or the thickness is too thin, it may be difficult to obtain sufficient bonding strength.If the thickness is too thick, the amount of resin used increases, which is not preferable from the viewpoint of disposal, and the width is If it is too wide, it may be difficult to obtain a sufficient internal volume of the free-standing bag.
[0016]
Although the manufacturing method of the self-supporting bag 1 is not particularly limited, as shown in FIGS. 3 and 4, a substantially halved portion of the edge joint portion on the one surface side of the edge of the bag body, and the upper end of the bag body. A first mold 5 in which a cavity for forming a closure part at a predetermined position is formed by an upper mold 5a and a lower mold 5b, and a cavity for forming the remaining part of the edge joint on the other surface side of the edge of the bag body. A second die 6 formed by 6a and a lower die 6b is provided. Filling ports 7 and 7 are provided in the upper die 5a and 6a, respectively, and the first die 5 and the second die 6 slide. It is a die slide injection method, using an injection molding machine A capable of in-mold molding and insert molding, using a resin film 2 ′ molded and folded in advance to have a predetermined self-standing bag shape, It is preferable to manufacture as follows.
[0017]
First, as shown in FIG. 3, the resin film 2 ′ is set on the lower mold 5b of the first mold 5, and then the upper mold 5a is lowered and one end of the resin film 2 ′ serving as the upper end of the bag body. The tapered tip 8a of the slide core 8 for forming the closure part is inserted between the films on the 2'a side so that the four-folded part of the other end 2'b forming the bottom surface of the bag body becomes one sheet. Set to. By setting the resin in this way and injecting the resin to the peripheral edge except for the lower end, a bottom that can be expanded is formed. Specifically, as the upper mold 5a descends, it faces one end 2′a and both end portions (not shown) of the resin film 2 ′, and as shown in FIG. A cavity 9a having a substantially halved shape of the edge joint portion is formed on one surface side of the portion to be the portion. The thermoplastic resin melted and softened by the filling port 7 provided in the upper die 5a, the eject mechanism (not shown) provided in the lower die 5b, and the vacuum drawing mechanism connected to the cavity is contained in the cavity of the first die 5. At the same time that the closure part is molded into a predetermined position on the upper end of the bag body, and at the same time, by the thermoplastic resin extending from the closure part, as shown in FIG. A substantially half body 4a of the edge joint portion is primarily molded on one side of the portion that becomes both side edges, and then the second mold 6 is slid. Similarly, as shown in FIG. By injecting into the cavity 9b of the two molds 6, secondary molding of the remaining part 4b of the edge joint part on the other surface side of the above part, and joining the part that becomes the upper edge of the bag body, both side edges, Form the edge joint 4 to hold the free standing bag To manufacture.
[0018]
Here, as described above, when the edge joint portion 4 is formed in two stages, the end portion of the resin film 2 ′ folded so as to have a bag body shape is formed by the thermoplastic resin injected into the cavity. The end part of the resin film 2 'is sandwiched between the center part of the edge joining part without the overlapping film end part being opened or being distorted in one direction when the film end part is overlapping. It can be joined in a state.
[0019]
The self-supporting bag is filled with contents (not shown) from the closure part to form a self-supporting shape with an expanded bottom surface, and after the closure part is sealed, it is stored and transported. In use, the contents can be discharged from the closure. The type of the content is not particularly limited, but is preferably fluid. For example, a liquid, a viscous material, a powder, a small-diameter solid form, or the like can be suitably accommodated. In this self-supporting bag, since the edge joint portions at both ends function as ribs, the self-supporting bag can maintain its self-supporting property until the contents disappear, and can be rounded down to be small when discarded.
[0020]
In addition, this invention is not restrict | limited to the said structure, You may change variously in the range which does not deviate from the summary of this invention.
[0021]
For example, depending on conditions such as film stiffness and resin moldability, it may be molded in one step. Instead of sliding the die as described above, a slidable pin is provided in the mold, and this pin In the state where the edge of the bag body is sandwiched so that it is in the center of the edge joint, the injection is performed halfway, the pin is slid and retracted, the remaining resin is injected, and the pin exists. Therefore, it is possible to fill the gap portion and to mold the edge joint portion to a predetermined thickness, and to fix it after joining.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view of a self-supporting bag for explaining a configuration example of the self-supporting bag of the present invention.
FIG. 2 is a schematic front view of the self-supporting bag.
FIG. 3 is a schematic diagram of an injection mold for explaining an example of the structure of the self-supporting bag manufacturing method of the present invention.
FIG. 4 is a schematic schematic view of the injection mold.
FIG. 5 is a schematic partial view of the injection mold.
FIG. 6 is another schematic partial view of the injection mold.
[Brief description of symbols]
DESCRIPTION OF SYMBOLS 1 Self-supporting bag 2 Bag main body 2a Side edge 2b Upper end edge 3 Closure part 4 Edge joint part

Claims (4)

A self-supporting bag having a closure portion at the top of a bag body, wherein both side edges and upper edge of the bag body are joined by an edge joint made of a thermoplastic resin covering the outer surface of these edges, and A self-supporting bag, wherein a closure part is integrally formed with the edge joint part. The self-supporting bag according to claim 1, wherein the edge joint portion of the bag body and the closure portion are formed by injection molding. The method for manufacturing a self-supporting bag according to claim 1, wherein when forming the edge joint portion of the bag body, a cavity is formed at the edge of the bag body, and a thermoplastic resin is injected into the cavity. A method for manufacturing a self-supporting bag, comprising forming an edge joint portion by joining edges of the bag body. The manufacturing method of the self-supporting bag according to claim 1, wherein when forming the edge joint portion of the bag body, the edge joint portion is substantially formed on one side of the edge of the bag body by a die slide injection method. A cavity having a half shape is formed, a thermoplastic resin is injected into the cavity to mold a substantially half body of the edge joint portion, and then the edge joint portion is formed on the other side of the edge of the bag body. Forming a cavity having a remaining shape, injecting a thermoplastic resin into the cavity to mold the remaining part of the edge joint part, and joining the edge of the bag body to form an edge joint part; The manufacturing method of the self-supporting bag characterized by this.

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