JP2020100414A - Flexible container and manufacturing method for the same - Google Patents

Abstract

To provide a flexible container excellent in durability of a conductive resin layer of an earth cable connection part, and a manufacturing method for the same.SOLUTION: When subjecting a conductive tarpaulin of a peripheral wall part 2 and an outer periphery part 4a of the conductive tarpaulin of a lower lid part 4 to high-frequency welding, the peripheral wall part 2, an earth cable connection part 7 and the outer periphery part 4a are subjected to high-frequency welding, in a state where a lower part of the earth cable connection part 7 is sandwiched between an upper part of the outer periphery part 4a and the peripheral wall part 2. An extending part 8 is protruded from the outer periphery part 4a. A conductive resin layer 11 of the conductive tarpaulin constituting the extending part 8 and a conductive resin layer 11 constituting the earth cable connection part 7 are arranged to face each other.SELECTED DRAWING: Figure 4

Description

The present invention relates to a flexible container in which a non-conductive resin layer is formed on a front surface, and a tarpaulin having a conductive resin layer formed on a back surface is joined, and a manufacturing method thereof.

Flexible containers, which are widely used for transporting and storing powders and granules, are subject to the properties of the powders and granules that are stored, and when pouring and discharging the powder granules at the inlet and outlet, vibration during transport, shock, etc. It is known that static electricity is generated by friction between powder particles or between the powder particles and the inner surface of the flexible container.

In order to release static electricity to the ground, the conductive tarpaulin is coated on the surface of the base fabric of the flexible container with a layer made of a rubber material (including a material made of thermoplastic resin) of conductivity-imparting type that is kneaded and mixed with carbon black. It is used. Further, a flexible container is used in which a part of the tarpaulin is extended to provide a tongue-shaped ground wire connecting portion, and the ground wire connecting portion can be held by a clip at the tip of the ground wire.

5 is a schematic side view of a commercially available flexible container (the left half is cut), and FIG. 6 is an enlarged view of a VI portion of FIG. Further, FIG. 7 is a sectional view of the same portion as FIG. 6 showing a state in which the ground wire connecting portion is deteriorated.

The flexible container 1 is provided on the substantially cylindrical peripheral wall portion 2, an upper lid portion 3 that covers the upper end side of the peripheral wall portion 2, a lower lid portion 4 that covers the lower end side of the peripheral wall portion 2, and the upper lid portion 3. The inlet 5 is provided, the outlet 6 provided in the lower lid 4, the earth wire connecting portion 7 ′ provided on the outer surface of the flexible container 1, and the like. Each of the inlet 5 and the outlet 6 has a substantially cylindrical shape having a diameter smaller than that of the peripheral wall portion 2. The inlet 5 extends upward from the center of the upper lid portion 3, and the outlet 6 is the lower lid portion 4. It extends downward from the center of. A ground wire connecting portion 7 ′ is provided on the lower outer peripheral surface of the peripheral wall portion 2.

Each part of the flexible container 1 is made of a conductive tarpaulin. As shown in the figure, the conductive tarpaulin has a conductive resin layer 11 formed on one surface of a base fabric and a non-conductive resin layer formed on the other surface. The conductive tarpaulin is provided with the conductive resin layer inside the flexible container 1. 5 to 7, the base cloth and the non-conductive resin layer are integrally shown and denoted by reference numeral 10.

As shown in FIG. 6, the outer peripheral portion 4 a of the conductive tarpaulin forming the lower lid portion 4 wraps around the lower outer peripheral surface of the peripheral wall portion 2 and is joined to the lower outer peripheral surface by high frequency welding or the like.

The ground wire connecting portion 7'is made of a tongue piece extending from the outer peripheral portion 4a of the conductive tarpaulin. When the powdery or granular material is stored in the flexible container 1, the ground wire connecting portion 7'is sandwiched by a ground clip (see FIG. 4, not shown in FIGS. 5 and 6) at the tip of the ground wire to ground the ground.

JP2012-250753A

The ground wire connecting portion 7'is originally intended to ground the flexible container 1 by sandwiching it with the ground clip at the tip of the ground wire as described above. However, at the time of actual work, an operator may try to move the flexible container 1 by grasping the ground wire connecting portion 7′ and pulling the ground wire connecting portion 7′ in the direction of arrow F in FIG. When the ground wire connecting portion 7'is pulled in this way, a strong tensile force is applied to the conductive resin layer 11, and as shown in FIG. 7, the conductive resin layer 11 cracks C near the root of the ground wire connecting portion 7'. May occur, and the electrical resistance between the conductive resin layer 11 of the ground wire connecting portion 7′ and the conductive resin layer 11 of the flexible container 1 may increase. The ground resistance from the ground terminal is specified by JIS C 61340-4-4 to be less than 1×10 ⁸ Ω.

An object of the present invention is to provide a flexible container having excellent durability of a conductive resin layer of a ground wire connecting portion and a method for manufacturing the flexible container.

The flexible container of the present invention is a flexible container in which a peripheral wall portion made of a conductive tarpaulin, a lower lid portion, and an upper lid portion are joined, and the conductive tarpaulin has a non-conductive resin layer formed on the front surface and a back surface. A conductive resin layer is formed on the conductive tarpaulin, and the conductive tarpaulin is provided with the conductive resin layer as the inner side of the flexible container, and the conductive tarpaulin forming the lower lid part or the upper lid part is formed. In a flexible container whose outer peripheral portion extends along the outer peripheral surface of the peripheral wall portion and is joined to the outer peripheral surface of the peripheral wall portion, conductive material is provided between the outer peripheral portion of the lower lid portion or the upper lid portion and the peripheral wall portion. Characterized in that the base portion of the ground wire connecting portion made of a conductive tarpaulin is sandwiched and joined to the outer peripheral portion and the peripheral wall portion, and the conductive resin layer of the ground wire connecting portion is located on the outer peripheral portion side. It is what

In one aspect of the present invention, an extending portion extending from the outer peripheral edge of the outer peripheral portion along the ground wire connecting portion is provided.

In one aspect of the present invention, the ground wire connecting portion is a free piece extending from the outer peripheral portion except for the lower portion, and the extension length of the free piece is the extension of the extending portion. Greater than length.

In one aspect of the present invention, the lateral width of the ground wire connecting portion on the base end side and the lateral width of the extending portion are substantially equal.

The method for producing a flexible container of the present invention is a method for producing the flexible container of the present invention, in which a conductive tarpaulin that constitutes the peripheral wall portion and an outer peripheral portion of the conductive tarpaulin that constitutes the lower lid portion or the upper lid portion are provided. The method further comprises a step of sandwiching the base portion of the ground wire connecting portion between them and high-frequency welding the conductive tarpaulins of the peripheral wall portion and the ground wire connecting portion to the lower lid portion or the upper lid portion.

In the flexible container provided by the present invention, by disposing the conductive resin layer in the ground wire connecting portion on the outer peripheral side, the ground wire connecting portion is provided near the base end portion of the ground wire connecting portion. Part of the conductive resin layer and the upper cover part or the lower cover part of the conductive resin layer having a total thickness. As a result, the tensile strength of the conductive layer is increased, cracking of the conductive layer is suppressed when the ground wire connecting portion is pulled, and sufficient grounding can be achieved.

The ground wire connecting portion overlaps with the extending portion, and the conductive resin layer of the ground wire connecting portion and the conductive resin layer of the extending portion overlap with each other to be electrically connected. Therefore, even if a worker repeatedly pulls the ground wire connecting part, and even if the conductive resin layer on the base end side of the ground wire connecting part cracks, the conductive resin layer of the ground wire connecting part is extended. Since the conductive resin layer of the entire flexible container is electrically connected to the conductive resin layer of the entire flexible container through the conductive resin layer of the portion with a low resistance, sufficient grounding can be achieved.

It is a cross-sectional perspective view of the flexible container according to the embodiment in the vicinity of the ground wire connecting portion. It is a cross-sectional perspective view of the flexible container according to the embodiment in the vicinity of the ground wire connecting portion. It is the IIA-IIA sectional view taken on the line of FIG. 1A. It is the IIA-IIA sectional view taken on the line of FIG. 1B. It is the III-III sectional view taken on the line of FIGS. 1A and 1B. It is sectional drawing of the same part as FIG. 2 which shows the state which connected the earth clip to the earth wire connection part. It is a side view of the conventional flexible container. FIG. 6 is an enlarged view of a VI portion of FIG. 5. It is sectional drawing which shows the deterioration state of a conductive resin layer.

Hereinafter, embodiments will be described with reference to FIGS. 1A to 4. 1A and 2A show an embodiment in which the extension portion 8 is not provided, and FIGS. 1B and 2B show an embodiment in which the extension portion 8 is provided.

Similar to the flexible container 1 shown in FIG. 5, the flexible container according to the embodiment shown in FIGS. 1A, 2A and 1B, 2B also has a peripheral wall portion 2, an upper lid portion 3, a lower lid portion 4, an inlet 5, and a drainage port. It has an outlet 6 and a ground wire connecting portion 7 (the upper lid portion 3, the inlet 5, and the outlet 6 are not shown in FIGS. 1 to 4). The outer peripheral portion 4a of the lower lid portion 4 rises along the outer peripheral surface of the peripheral wall portion 2 and is joined to the outer peripheral surface of the peripheral wall portion 2 by high frequency welding or the like. A joining method other than high frequency welding may be adopted.

Also in these embodiments, the peripheral wall portion 2, the upper lid portion 3 and the lower lid portion 4 are each made of a conductive tarpaulin. The conductive resin layer 11 of the peripheral wall portion 2 is located on the inner surface side of the flexible container, the conductive resin layer 11 of the upper lid portion 3 is located on the lower surface side of the upper lid portion 3, and the conductive resin layer 11 of the lower lid portion 4 is located. Is located on the upper surface side of the lower lid portion 4.

In these embodiments, the ground wire connecting portion 7 is made of a conductive tarpaulin formed separately from the conductive tarpaulins forming the peripheral wall portion 2 and the lower lid portion 4.

The conductive tarpaulin that constitutes the ground wire connecting portion 7 is, for example, a substantially rectangular shape having a horizontal width of 20 to 200 mm and a vertical length of 30 to 100 mm, but the shape and dimensions thereof are not limited thereto. The conductive tarpaulin forming the ground wire connecting portion 7 is arranged such that the conductive resin layer 11 is on the outer peripheral portion 4a side and the non-conductive resin layer 10 is on the peripheral wall portion 2 side.

The lower portion (base portion) of the ground wire connecting portion 7 is sandwiched between the outer peripheral portion 4a of the lower lid portion 4 and the lower portion of the peripheral wall portion 2 and joined to both the outer peripheral portion 4a and the peripheral wall portion 2 by high frequency welding or the like. Has been done.

Except for the lower portion of the ground wire connecting portion 7, it is in the shape of a free piece extending upward from the outer peripheral portion 4a. The free piece portion of the ground wire connecting portion 7 is not joined to the peripheral wall portion 2. Furthermore, it is not joined to the extending portion 8 described later.

In FIG. 1A and FIG. 2A, the extension part 8 is not provided. In FIG. 1B and FIG. 2B, the extending portion 8 extends from a portion of the outer peripheral edge of the outer peripheral portion 4 a of the conductive tarpaulin that constitutes the lower lid portion 4, overlapping the ground wire connecting portion 7. The lateral width of the extending portion 8 is substantially the same as the lateral width of the ground wire connecting portion 7, but it may be slightly longer than that. The extension length of the extension portion 8 is preferably about 3 to 50 mm, particularly about 5 to 20 mm, but is not limited to this.

Other configurations of the flexible container of FIGS. 1A, 2A and 1B, 2B are the same as those of the flexible container 1 shown in FIGS.

Also in the flexible containers according to these embodiments, grounding is performed by mounting the ground clip 9 (FIG. 4) at the tip of the grounding wire so as to sandwich the free piece portion of the grounding wire connecting portion 7.

Also in these embodiments, an operator may pull the ground wire connecting portion 7. If the worker repeatedly pulls the ground wire connecting portion 7, the conductive resin layer 11 may be cracked on the base end side of the ground wire connecting portion 7 as in the case of FIG. 7.

In the embodiment of FIGS. 1A, 2A and 1B, 2B, the conductive resin layer 11 in the ground wire connecting portion 7 is arranged so as to be on the outer peripheral portion 4a side, so that the ground wire connecting portion 7 has a base. A conductive layer having a total thickness of the conductive resin layer 11 of the ground wire connecting portion 7 and the conductive resin layer 11 of the upper lid portion 3 or the lower lid portion 4 is formed near the end portion. This increases the tensile strength of the conductive layer and suppresses cracking of the conductive layer when the ground wire connecting portion 7 is pulled. Therefore, even if the ground clip sandwiches only the ground wire connecting portion 7, sufficient grounding can be achieved.

In the embodiment of FIGS. 1B and 2B, as shown in FIG. 4, the free piece portion of the ground wire connecting portion 7 hangs downward when the ground clip 9 is connected and overlaps the extending portion 8 to form the ground wire. The conductive resin layer 11 of the connecting portion 7 and the conductive resin layer 11 of the extending portion 8 are overlapped with each other and electrically connected. Therefore, even if a crack occurs in the conductive resin layer 11 on the base end side of the free piece portion of the ground wire connecting portion 7, the conductive resin layer 11 of the ground wire connecting portion 7 will not be affected by the conductive resin of the extending portion 8. Through the layer 11, the conductive resin layer 11 of the entire flexible container is electrically connected with low resistance, and sufficient grounding can be established.

The thickness of the conductive resin layer 11 of the conductive tarpaulin is 0.01 to 1 mm, preferably 0.02 to 0.1 mm, and the thickness of the non-conductive resin layer 12 is 0.1 to 3 mm, particularly It is preferably 0.2 to 1 mm.

[Material, etc.]
Examples of the material of the conductive tarpaulin forming each part of the flexible container 1 include the following, but the material is not limited to these.

Examples of the base fabric of the conductive tarpaulin include woven fabrics made of natural fibers such as cotton and hemp, and synthetic fibers such as polyester fibers, polyamide fibers and vinylon fibers. The base fabric may be a filament or steebles formed by using these fibers alone or in combination of two or more kinds. The woven fabric means a woven fabric or knitted fabric in which these fibers are woven into a plain woven fabric, a twill woven fabric, a satin woven fabric, etc., and the kind and structure of the knitted woven fabric is one that does not impair the flexibility of the conductive tarpaulin, There is no particular limitation.

As the woven fabric constituting the base fabric, a plain woven fabric having a fiber thickness of 500 to 1000 denier and a driving number of 15 to 30 fibers/inch is preferable. When a woven fabric made of polyester fibers or polyamide fibers is used, a flat woven fabric having a fiber thickness of 750 denier and a striking number of 20×20/inch is suitable as the woven fabric. Such a woven fabric generally has a thickness of 0.2 to 2 mm and a width of about 0.5 to 3 m.

The non-conductive resin layer is preferably composed of a thermoplastic resin composition, and particularly preferably composed of a resin layer containing a copolymer layer of ethylene and vinyl acetate. The resin layer containing a copolymer layer of ethylene and vinyl acetate includes a resin layer consisting of a single layer of a copolymer layer of ethylene and vinyl acetate, a copolymer layer of ethylene and vinyl acetate and other layers. It may be a multilayer resin layer in which a resin layer is laminated. As the resin forming the other resin layer, polyvinyl chloride, polyvinyl chloride resin such as vinyl chloride copolymer containing vinyl chloride as a main component, polyethylene such as low density polyethylene, high density polyethylene and chlorinated polyethylene. -Based resins, ethylene-acrylic acid copolymers (EMA), ethylene-methyl methacrylate copolymers (EMMA), ethylene-acrylic acid copolymers such as ethylene-ethyl acrylate copolymer (EEA), polyurethanes , Polyvinyl acetate and the like, but are not limited thereto.

As the ethylene-vinyl acetate copolymer, those having a component polymerization ratio of ethylene and vinyl acetate of 90:10 to 70:30 are preferable. If the proportion of vinyl acetate is less than 10% by mass, the high frequency welding process becomes difficult, and if it exceeds 30% by mass, the heat resistance becomes poor, which is not preferable. A particularly preferred range of the component polymerization ratio of ethylene and vinyl acetate is 85:15 to 75:25. As the ethylene-vinyl acetate copolymer, the melt flow rate (MFR) measured under the conditions of a temperature of 190° C. and a load of 21.28 N (2.16 kgf) according to JIS K7210 is in the range of 0.1 to 5.0. Those in the range of 0.5 to 2.0 are particularly preferable.

The conductive resin layer 11 is preferably made of a thermoplastic resin composition containing conductive carbon black, and is particularly composed of a conductive carbon black and a resin layer containing an ethylene-vinyl acetate copolymer layer as a main component. It is preferable. The resin layer containing the conductive carbon black and the ethylene-vinyl acetate copolymer layer as the main component means a single layer of the ethylene-vinyl acetate copolymer layer (polyolefin resin layer) as the main component containing the conductive carbon black. In addition to the above resin layer, it may be a multilayer resin layer in which another resin layer is laminated on this layer. Other resin layers As the resin forming the resin layer, polyethylene resin such as low density polyethylene, high density polyethylene, chlorinated polyethylene, polypropylene, polypropylene resin such as propylene-ethylene copolymer, ethylene-methyl acrylate copolymer Examples of the polymer include ethylene-acrylic copolymers such as ethylene-methyl methacrylate copolymer and ethylene-ethyl acrylate copolymer. In addition, the other resin layer may include a thermoplastic resin layer containing a specific amount of conductive carbon black.

There is no particular limitation on the conductive carbon black blended in the conductive resin layer, but when the average surface area of the conductive carbon black is relatively small, the amount of the conductive carbon black used becomes large, Disadvantages such as deterioration of fluidity when the thermoplastic resin is formed into a film and extreme decrease in strength of the film are significant. From the viewpoint of physical properties, the conductive carbon black preferably has an average surface area of 30 m ² /g or more, and particularly preferably an average surface area of 100 m ² /g or more.

The amount of conductive carbon black compounded with respect to the thermoplastic resin, preferably a resin containing an ethylene-vinyl acetate copolymer, is preferably 0.1 to 25 parts by mass with respect to 100 parts by mass of the thermoplastic resin. When the blending amount of the conductive carbon black is less than 0.1 parts by mass, the surface specific resistance of the conductive resin layer 11 becomes large and the conductivity is hard to be improved, which is not preferable. When the blending amount of the conductive carbon black exceeds 25 parts by mass, the surface specific resistance of the conductive resin layer 11 becomes small and the conductivity is improved, but the flexibility of the tarpaulin is impaired and the high frequency welding process is performed. This is not preferable because it may increase the risk of sparks. A particularly preferable blending amount of the conductive carbon black with respect to 100 parts by mass of the thermoplastic resin is 3 to 15 parts by mass.

In order to manufacture the flexible container of the present invention, during high frequency welding of the conductive tarpaulin of the peripheral wall portion 2 and the outer peripheral portion 4a of the conductive tarpaulin of the lower lid portion 4, between the upper portion of the outer peripheral portion 4a and the peripheral wall portion 2 is performed. The peripheral wall portion 2, the lower portion of the ground wire connecting portion 7, and the outer peripheral portion 4a may be welded by high frequency sandwiching the lower portion of the ground wire connecting portion 7.

In this way, when the lower portion of the ground wire connecting portion 7 is sandwiched between the peripheral wall portion 2 and the outer peripheral portion 4a and high frequency welding is performed, the thickness of the portion sandwiching the ground wire connecting portion 7 (from the inner surface to the outer peripheral portion of the peripheral wall portion 2) is increased. The thickness up to the outer surface of the portion 4a) becomes large. Then, as shown in FIG. 3, a step is formed between the portion sandwiching the ground wire connecting portion 7 and its surroundings. In order to reduce this step, it is preferable that the thickness of the tarpaulin that constitutes the ground wire connecting portion 7 be smaller than the thickness of the tarpaulin that constitutes the peripheral wall portion 2 and the lower lid portion 4.

The above-described embodiment is an example of the present invention, and the present invention may have a mode other than that shown in the drawings. For example, in the above embodiment, the ground wire connecting portion 7 has a substantially rectangular shape, but it may have a trapezoidal shape or the like in which the width becomes smaller toward the tip side of the free piece portion. In the present invention, when the ground resistance of the ground wire connecting portion 7 becomes large, the ground wire connecting portion 7 and the extending portion 8 may be overlapped and repaired by high frequency welding.

In the above-described embodiment, the ground wire connecting portion 7 is arranged between the lower lid portion 4 and the peripheral wall portion 2, but the ground wire connecting portion may be arranged between the upper lid portion 3 and the peripheral wall portion 2. Good. The configuration in this case is vertically symmetrical in FIGS.

[Example 1]
A flexible container shown in FIGS. 1 to 3 was manufactured in which the peripheral wall portion 2 and the lower lid portion 4 were made of tarpaulin having a thickness of 0.80 mm, and the ground wire connecting portion 7 was made of tarpaulin having a thickness of 0.60 mm. The ground wire connecting portion 7 was a square having a side of 50 mm, and a range of 10 mm on the base end side was sandwiched between the outer peripheral portion 4 a and the peripheral wall portion 2 and subjected to high frequency welding.

The extending portion 8 has a lateral width of 50 mm and a height of 10 mm.

The earth wire connecting portion 7 was pulled 10 times in the direction perpendicular to the outer peripheral portion 4a (direction F in FIG. 5) at 294N (30 kg) or 392N (40 kg) (load was applied at a speed of 500 N/min to 294 N and 392 N). When it reached, it finished pulling once). Before and after the pulling, a ground clip was attached to the ground wire connecting portion 7 to measure the resistance between grounds. The results are shown in Table 1.

[Example 2]
The same flexible container as in Example 1 was manufactured, and the pulling direction during the pulling test was a direction in which the ground wire connecting portion 7 and the extending portion 8 were folded back 180° along the outer peripheral portion 4a (vertically downward direction in FIG. 2). As a result, a tensile test was performed to measure the resistance between grounds. The results are shown in Table 1.

[Comparative Example 1]
The same tensile test as in Example 2 was performed except that the ground wire connecting portion had the configuration of FIG. 6 (width 50 mm, protrusion length 40 mm). The results are shown in Table 1.

[Discussion]
As shown in Table 1, in Examples 1 and 2, even if the ground wire connection portion is repeatedly pulled, the resistance between grounds does not increase or hardly increases. On the other hand, in Comparative Example 1, it is recognized that the resistance between grounds increases due to the pulling, and in particular, the resistance between grounds increases when the turn-back angle of the ground wire connecting portion increases.

1 flexible container 2 peripheral wall part 3 upper cover part 4 lower cover part 5 input port 6 discharge port 7, 7'ground wire connection part 8 extension part 9 ground clip 10 base cloth and non-conductive resin layer 11 conductive resin layer

Claims (5)

A flexible container formed by joining a peripheral wall portion made of a conductive tarpaulin, a lower lid portion and an upper lid portion,
The conductive tarpaulin has a non-conductive resin layer formed on the front surface and a conductive resin layer formed on the back surface,
The conductive tarpaulin is provided with the conductive resin layer as the inner side of the flexible container,
In a flexible container in which the outer peripheral portion of the conductive tarpaulin forming the lower lid portion or the upper lid portion extends along the outer peripheral surface of the peripheral wall portion, and is joined to the outer peripheral surface of the peripheral wall portion,
Between the outer peripheral portion and the peripheral wall portion of the lower lid portion or the upper lid portion, the base portion of the ground wire connecting portion made of a conductive tarpaulin is sandwiched and joined to the outer peripheral portion and the peripheral wall portion,
A flexible container characterized in that the conductive resin layer of the ground wire connecting portion is located on the outer peripheral side. The flexible container according to claim 1, further comprising an extending portion extending from an outer peripheral edge of the outer peripheral portion along the ground wire connecting portion. Of the ground wire connecting portion, other than the base portion is a free piece extending from the outer peripheral portion,
The flexible container according to claim 1 or 2, wherein the extension length of the free piece is larger than the extension length of the extension portion. The flexible container according to any one of claims 1 to 3, wherein a left-right width of the base end side of the ground wire connecting portion and a left-right width of the extending portion are substantially equal to each other. A method of manufacturing the flexible container according to any one of claims 1 to 4, comprising:
The base portion of the ground wire connecting portion is sandwiched between the conductive tarpaulin forming the peripheral wall portion and the outer peripheral portion of the conductive tarpaulin forming the lower lid portion or the upper lid portion, and the peripheral wall portion and the ground wire connecting portion and the lower lid portion. A method of manufacturing a flexible container, the method including a step of high-frequency welding each conductive tarpaulin with the upper portion or the upper lid portion.

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