JP2003191964A - Self-standing bag and manufacturing method thereof - Google Patents

Abstract

(57) Abstract: A self-standing bag (1) having a bag body (2) having a closure portion (3), wherein both side edges (2a, 2a) and an upper edge (2b) of the bag body (2) cover outer surfaces of these edges. Joined by an edge joint 4 made of a thermoplastic resin, the closure 3
The self-standing bag 1 is formed integrally with the edge joining portion 4. [Effect] The self-standing bag of the present invention is flexible and has excellent self-supporting properties. Therefore, when used, the self-standing bag functions as a self-supporting packaging bag. Satisfactory, it can be rolled up and discarded after use in a small capacity, and the attachment strength of the closure portion is excellent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-supporting bag having a closure portion, and more particularly to a self-supporting bag which is flexible and has excellent self-supporting property and attachment strength of the closure portion.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
Self-supporting bags for fluids such as liquids are mainly used for refilling, and their self-sustainability is not so important. For example, when the content of the bag is reduced to 1/3 or less, the upper part of the bag bends and becomes a self-supporting bag. Had no function of. In particular, a self-supporting bag for fluid may be provided with a closure part for pouring out contents, and in such a case, the upper part becomes heavy, and lack of self-supporting property becomes remarkable. It was Also,
The conventional self-standing bag with a closure part, the peripheral part of the bag body is joined by heat welding, the closure part is molded separately from it, and the closure part is manually inserted between the sheets forming the bag body, The closure was attached by heat welding to the inner surface of the seat. Such manual work not only affects mass productivity, but also causes insufficient heat welding between the closure portion and the sheet, which may result in insufficient strength of the bag body. On the other hand, the molded container naturally has sufficient self-supporting property, but could not be folded and made small at the time of disposal.

The present invention has been made in view of the above circumstances. When used, the function as a self-standing bag is retained until the contents are exhausted, and at the time of disposal, it can be folded to reduce the capacity and the closure portion. It is an object of the present invention to provide a self-supporting bag having excellent attachment strength and a method for manufacturing the self-supporting bag suitable for manufacturing the self-supporting bag.

[0004]

That is, the present invention is a self-standing bag having a closure portion on the upper portion of a bag body, wherein both side edges and upper edges of the bag body cover outer surfaces of these edges. Joined by the edge joining part made of thermoplastic resin,
Also, there is provided a self-supporting bag, wherein the closure part is integrally molded 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.

The present invention is also the method for manufacturing the above-mentioned self-standing bag, wherein a cavity is formed at the edge of the bag body when forming the edge joint portion of the bag body, and the cavity is made of thermoplastic resin. Provided is a method for manufacturing a self-supporting bag, characterized in that an edge joining portion is formed by injecting resin to join the edges of the bag body. Here, when forming the edge joint portion of the bag body, by a die slide injection method, to form a cavity that is substantially half of the edge joint portion on one surface side of the edge of the bag body, A thermoplastic resin is injected into the cavity to mold a substantially half body of the edge joint portion, and then a cavity that is the shape of the remaining portion of the edge joint portion is formed on the other surface side of the edge of the bag body. It is more preferable to form the edge joint portion by injecting a thermoplastic resin to mold the remaining portion of the edge joint portion and joining the edge portions of the bag body.

That is, in the self-standing bag of the present invention, since the upper edge and both side edges of the bag body are joined by the edge joining portions made of thermoplastic resin covering the outer surfaces of these edges, The edge joints become so-called ribs of the bag body, and function as the pillars of the bag to improve the self-supporting property of the bag body, and even if the closure part is provided on the upper part of the bag body, it is enough Independence can be maintained. Since the closure part is integrally molded with the edge joint part, the attachment strength of the closure part is also excellent.

Here, if the edge joint portion of the bag body and the closure portion are formed by injection molding, the edge joint portion can be easily and surely formed by, for example, a die slide injection method. This is more preferable because the closure part can be integrally molded at the same time.

In the method for producing a self-supporting bag of the present invention, a cavity is formed in the edge of the bag body when the edge joint portion of the bag body is formed, and a thermoplastic resin is injected into the cavity to form the cavity. A method for manufacturing a self-supporting bag, characterized in that an edge joining portion is formed by joining edges of a bag body.
For example, when forming the edge joint of the bag body of the self-supporting bag, a die slide injection method is used to form a cavity that is a substantially half of the edge joint on one side of the edge of the bag body. , A thermoplastic resin is injected into the cavity to mold a substantially half body of the edge joint portion, and then a cavity which becomes the remaining shape of the edge joint portion is formed on the other surface side, and the thermoplastic resin is injected into the cavity. By injecting and molding the remaining part of the edge joint, by joining the edges of the bag body,
This is a manufacturing method for forming an edge joint. 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 with the sheets overlapped with each other. When the outer edge of the bag body is covered with the thermoplastic resin, the edge of the bag body can be surely arranged in the resin center (the center of the joint), as compared with the case where the edge edge joint is formed by using the thermoplastic resin. So
It is preferable because the edges of the bag body can be joined more easily and reliably.

[0009]

EFFECTS OF THE INVENTION Since the self-standing bag of the present invention is flexible and excellent in self-supporting property, it can function as a packaging bag having self-supporting property at the time of use. Satisfying the requirement, it can be rolled up into a small volume after use and discarded.
It also has excellent attachment strength for the closure part.
Therefore, the self-standing bag of the present invention is easy to use at the time of use, can be easily reduced in volume at the time of disposal after use, and is suitable for environmental protection. Further, according to the method for manufacturing a self-supporting bag of the present invention, it is possible to easily and reliably manufacture a self-supporting bag having the above-mentioned characteristics and particularly excellent in the bonding strength of the bag body.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 and FIG. 2 explain an example of the structure of the self-standing bag of the present invention.
2 is a schematic perspective view showing a state where the self-standing bag 1 is inflated, and FIG. 2 is a schematic front view showing a state where the self-standing bag 1 is folded. The self-standing bag 1 is provided with a closure part 3 at the upper end of the bag body 2, is folded so that the lower side of the long film forming the bag body 2 is folded in four, and one side edge 2a to A bottom surface 2c is formed by joining the upper edge 2b to the other edge 2a.

As the bag body 2, a single-layer or multi-layer film is used. These films are not necessarily required to have a heat-welding property like conventional films, but when formed into a bag, it is preferable that the film surface on the outer side has good adhesion to the resin to be injected. The multilayer film is a co-extruded film, a laminated film, or the like, and, for giving 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 film of a coextrusion type or a laminate type of these is preferably used.

The thickness of the film is 20 to 900 μm.
m is applied, and a thick film is suitable from the standpoint of self-supporting property, but even if it is a thin film from the viewpoint of flexibility and lightness, the self-supporting property can be secured by providing the side edge joint portion.
From the viewpoint of moldability and handleability, the desirable thickness is 1
A range of 00 to 200 μm is suitable. The film is not limited to a synthetic resin film, and may be a single layer product or a laminated product of paper or metal foil.

The shape and size of the closure part 3 are not particularly limited, and may be any shape and size according to the purpose of use of the packaging bag. Here, usually, a self-standing bag with a closure part is manufactured by inserting a closure member into the upper end portion of the self-supporting bag by another operation using a hand or an automatic insertion machine, and heat-welding the closure member. In the case of a thick material, it is difficult to surely bond the both ends of the closure member, and the welding operation is often difficult. However, in the present invention, since it is integrally injection-molded with the edge joint portion 4 as described later, there is no such difficulty.

The edge joining portion 4 is formed by injection molding at the same time as the closure portion 3 or by molding the closure portion 3 first and then integrally molding it in a mold. The forming resin is not particularly limited 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 or polypropylene resin, or injectable plastic such as nylon or polyester. Blends or copolymer resins of various engineering resins and elastomers can also be used.

The edge joining portion 4 is formed along the one side edge 2a to the upper edge 2b to the other side edge 2a of the bag body 2 made of a resin film which is molded in advance into a predetermined self-standing bag shape. The width and the thickness are not particularly limited, but the width (arrow w in FIG. 1) is 1 to 20 mm, particularly 5 to 10.
mm, thickness (arrow d in FIG. 1) 1 to 10 mm, especially 2
It is preferable that it is formed to have a thickness of 5 mm. If the width is too narrow or the thickness is too thin, it may be difficult to obtain sufficient bonding strength, and 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 inner volume of the self-supporting bag.

The method for producing the self-supporting bag 1 is not particularly limited, but as shown in FIGS. 3 and 4, a substantially half body of the edge joint portion on one side of the edge of the bag body, and the bag body. The upper mold 5 is provided with a cavity forming a closure part at a predetermined position on the upper end of the
a and a lower mold 5b, a first mold 5 and a second mold 6 in which a cavity for forming the remaining portion of the edge joining portion is formed on the other side of the edge of the bag body by the upper mold 6a and the lower mold 6b. Is a die slide injection method having a structure in which the first mold 5 and the second mold 6 are slid while the upper molds 5a and 6a are respectively provided with the filling ports 7 and 7, and the molds are in-molded or inserted. It is preferable to use an injection molding machine A capable of molding and use a resin film 2 ′ that has been previously molded into a predetermined self-supporting bag shape and has been folded and manufactured as follows.

First, as shown in FIG. 3, the resin film 2'is set on the lower die 5b of the first die 5, and then the upper die 5a.
And the tapered tip 8a of the slide core 8 for forming the closure part is inserted between the films of the resin film 2'on one end 2'a side which is the upper end of the bag body to form the bottom surface of the bag body. Set the other end 2'b so that the four-folded portion becomes one sheet. By setting in this way and injecting resin into the peripheral part excluding the lower end,
A bottom surface that can be expanded is formed. Specifically, the upper mold 5a
As shown in FIG. 5, one end 2′a of the resin film 2 ′ and both end portions (not shown) of the resin film 2 ′ are exposed to one side of the upper end peripheral portion and side wall peripheral portion of the bag body. A cavity 9a is formed which is a substantially half shape of the edge joint portion. Then, the thermoplastic resin melted and softened by the filling port 7 provided in the upper mold 5a, the eject mechanism (not shown) provided in the lower mold 5b, and the vacuum drawing mechanism connected to the cavity is inside the cavity of the first mold 5. Then, the closure part is molded at a predetermined position on the upper end of the bag body, and at the same time, the thermoplastic resin extending from the closure part causes the resin film 2 ′ to have an upper end edge of the bag body as shown in FIG. Approximately half-divided body 4a of the edge joint portion on one surface side of the portion which becomes the both end edges
Is first molded, then the second mold 6 is slid, and similarly, a thermoplastic resin is injected into the cavity 9b of the second mold 6 as shown in FIG. The remaining portion 4b of the edge joining portion is secondarily molded, and the upper edge and both end portions of the bag body are joined to form the edge joining portion 4 to manufacture the self-standing bag.

Here, as described above, when the edge joining portion 4 is formed in two steps, the end portion of the resin film 2'folded into a bag body shape is injected into the cavity. The plastic resin does not open the overlapped film ends or distort the film ends in one direction when the film ends are overlapped. It can be joined in the state of being sandwiched between.

The self-standing bag is filled with contents (not shown) from the closure part to form a self-supporting shape with a wide bottom surface, and the closure part is sealed and then stored and transported. When used, the contents can be discharged from the closure part. The kind of the content is not particularly limited, but a material having fluidity is suitable, and for example, a liquid, a viscous material, a powder, a solid shape having a small diameter, or the like can be suitably stored. In this self-supporting bag, since the edge joints at both ends function as ribs, the self-supporting bag can maintain its self-supporting property until the contents are exhausted, and can be rolled and made smaller at the time of disposal.

The present invention is not limited to the above-mentioned constitution, and various modifications may be made without departing from the gist of the present invention.

For example, depending on the conditions such as the rigidity of the film and the moldability of the resin, the molding may be carried out in one step. Instead of sliding the die as described above, a slidable pin is provided in the mold. , With this pin, injection is performed up to the middle stage with the edge of the bag main body being sandwiched so that it comes to the center of the edge joint, slide the pin back, and inject the remaining resin, It is also possible to fill the voids due to the existence of the above, and to mold the edge joint portion to have a predetermined thickness, and fix it after joining.

[Brief description of 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-standing bag.

FIG. 3 is a schematic diagram of an injection molding die for explaining one configuration example of the method for manufacturing the self-supporting bag of the present invention.

FIG. 4 is a schematic diagram of the injection molding die.

FIG. 5 is a schematic partial view of the injection molding die.

FIG. 6 is another schematic partial view of the injection molding die.

[Simple explanation of symbols]

1 freestanding bag 2 bags body 2a side edge 2b Upper edge 3 Closure part 4 Edge joint

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B31B 29/84 B31B 29/84 // B29L 22:00 B29L 22:00 (72) Inventor Kazuhiro Ikeda Tokyo Chuo-ku, Nihonbashi-Bakuro-cho, 1-4-16 Fujimori Kogyo Co., Ltd. (72) Inventor Kazumi Usami, No.5 Tamagawa-cho, Kanazawa, Ishikawa Prefecture Mitani Sangyo Co., Ltd. (72) Inventor, Takaaki Katsuhara Tokaichi, Naka-ku, Hiroshima 2-1-1, Machi F-term in Acty Co., Ltd. (Reference) 3E064 AB23 BA24 BA36 BA54 BB03 BC08 BC18 EA23 EA30 FA04 HF10 HG02 HG03 HN65 3E075 AA09 BA47 BB22 CA01 DD30 DD45 DD47 DE03 GA04 4F206 AG23 JHC JJJC28 J01 J28C01

Claims (4)

[Claims] 1. A self-supporting bag having a closure portion on the upper portion of the bag body, wherein both side edges and an upper edge of the bag body are
A self-supporting bag, characterized in that it is joined by an edge joining portion made of a thermoplastic resin that covers the outer surfaces of these edges, and the closure portion is integrally molded with the edge joining portion. 2. 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. 3. The method for manufacturing a self-supporting bag according to claim 1, wherein a cavity is formed in an edge of the bag body when the edge joint portion of the bag body is formed, and the cavity is formed of a thermoplastic resin. A method for manufacturing a self-supporting bag, characterized in that an edge joining portion is formed by injecting a resin to join the edges of the bag body. 4. The method for producing a self-supporting bag according to claim 1, wherein when forming the edge joint portion of the bag body, a die slide injection method is used to form an edge on one side of the edge of the bag body. A cavity having a substantially half shape of the edge joint portion is formed, a thermoplastic resin is injected into the cavity to mold a substantially half body of the edge joint portion, and then on the other surface side of the edge of the bag body. By forming a cavity having the shape of the remaining portion of the edge joint portion, injecting a thermoplastic resin into the cavity to mold the remaining portion of the edge joint portion, and by joining the edge portions of the bag body, the edge joint is formed. A method for producing a self-supporting bag, which comprises forming a portion.