JPH06247492A - Base cloth for electricity controllable flexible container - Google Patents

Abstract

PURPOSE:To provide a flexible container in which no special processes are required in the weaving and sewing of container base cloth, and while an increase in an amount of material is minimized, satisfactory function is provided and the strength and usage of the container are not impaired. CONSTITUTION:Cloth is made by weaving flat yarn obtained by slitting a thermoplastic synthetic resin film and stretching each strip. In this cloth, conductive threads that are organic conductive fibers with a fiber surface resistance of 10<0>-10<5>OMEGA/cm and a strength of 500gf or more, as substitute threads for parts of warp or weft flat yarn or as increase threads, are woven to form a stripe or a grid pattern. Thus, a base cloth used for an electricity controllable flexible container is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible container used for transportation and storage of powder and granules.

[0002]

2. Description of the Related Art Recently, a flexible container using a base cloth woven from a flat yarn, which has a high strength by slitting and stretching a synthetic resin film, is used as a powder grain for industrial raw materials or food raw materials. Contributes to the transport or storage of the body. This flexible container is lightweight, inexpensive, and is used in large quantities because of its transportation efficiency advantages such that it can be folded and carried when not in use.

However, in a flexible container, since the base cloth is made of synthetic resin, the surface resistivity is large, and when the powder or granules are loaded into the container or the container is loaded into the reaction kettle, silo, etc. It has been pointed out that static electricity is likely to be generated due to contact and friction with the particles, which may cause ignition or dust explosion due to spark discharge. For this reason, studies have been conducted on methods of handling flexible containers that suppress static electricity generation (Japanese Patent Laid-Open No. 64-17397, etc.) and static antistatic type flexible containers.For example, a conductive film is laminated on a base fabric. thing
(Actual No. Sho 63-66224), Laminated base resin with antistatic resin (Japanese Patent Laid-Open No. 4-226755), Equipped with a ground terminal for earth (Act No. 4-30153), electrified There are ones that let the wire escape through a hanging hand (Jitsuhei 4-30154) and ones that weave twisted yarns of conductive fiber and resin fiber (Jitsukai Sho 63-85680).

[0004]

However, these electrostatic antistatic type flexible containers are not satisfactory in terms of performance, and due to the increase in raw materials and the increase in cost due to the complicated manufacturing process, electrostatic charging is not possible. Although there is a desire for prevention, it has not yet spread to the market. Therefore, it is possible to provide a flexible container that does not require a special process for weaving or sewing a container base fabric, is fully functionally satisfied while suppressing an increase in raw materials as much as possible, and does not impair the strength and usability of a conventional container. As a result of intensive studies aimed at, the present invention has been achieved.

[0005]

DISCLOSURE OF THE INVENTION The present invention relates to a woven fabric obtained by woven a flat yarn obtained by slitting and stretching a thermoplastic synthetic resin film, in which one of the warp yarn and the weft yarn is part of the flat yarn. A base cloth for an antistatic flexible container in which conductive filaments are struck in a striped manner as replacement yarns or additional yarns, and both warp and weft yarns have a grid of conductive filaments as replacement yarns or additional yarns in a part of the flat yarn. The problem was solved by using a base fabric for an antistatic flexible container that is formed into a shape.

Here, the thermoplastic synthetic resin used for the flat yarn is a high density polyethylene, polypropylene, polyester, nylon or the like alone or in a mixture. An amorphous film is formed from these synthetic resins by the T-die method or the inflation method with an extruder, and about 10
After slitting to a width of ~ 20 mm, it is stretched and oriented in the machine direction, and then heat treated to obtain a flat yarn, but due to the creep resistance and strength as a flexible container, and the low cost of raw materials, polyolefin synthetic resin is used. It is suitable.

In woven flat yarn, a plain weave is generally used as a woven structure, but a twill weave or a leno weave can be selected. Here, in order to conform to the physical properties of the base fabric of the Japan Flexible Container Industry Association as a standard for one-way containers, which is basically used once, the flat yarn of the warp and weft yarns has a fineness of 1,000- 2,000 denier and strength of 5 g / d or more are required, and in order to make the flexible container lightweight, highly strong and flexible, it is more preferable to densely weave flat yarn with a fineness of 1,300 to 1,600 denier and a strength of 5.3 g / d or more. It was made.

The conductive filamentous material is used to prevent electrostatic charge, and there are many metal fibers such as thin metal wires, carbon fibers obtained by firing carbonization of acrylic fibers and rayon fibers. However, when it is used as a base fabric for a flexible container, organic conductive fibers are preferable because they have physical strength, specific gravity, and texture close to that of synthetic resin and are well suited to the loom. Examples of the organic conductive fiber include a composite fiber formed by spinning a polymer in which a conductive component such as metal, a metal compound, and carbon is dispersed as fine particles, a metal-plated fiber coated with a metal component on the surface of an organic fiber by a vapor deposition method, an organic Examples thereof include those in which a metal compound is attached to the fiber surface by a chemical bond.

Regarding the conductive performance of the conductive filamentous material, the conductivity is not obtained when the surface resistance value is large, and it can be said that the smaller surface resistance value is more preferable from the viewpoint of antistatic. However, a thread-like material having a small surface resistance value has a problem that it becomes more metallic and has poor flexibility due to a high content of a conductive component, which has an adverse effect on weaving, sewing and the like, and a function deterioration due to surface oxidation. In order to impart antistatic property, the effect is recognized if the surface resistance value is 10 ⁵ Ω / cm or less, but in the present invention, the surface resistance value is 10 5 in consideration of the environment, the kind of charged material and the woven density. It is preferably ⁰ to 10 ⁵ Ω / cm. Further, from the viewpoint of strength, it is preferable to have a tensile strength of 500 gf or more in view of the need for mechanical strength that does not reduce the weaving efficiency of the loom.

In order to impart antistatic properties to the base fabric for flexible containers, conductive filaments are used.
Since conductive filaments are more expensive than flat yarn and it is difficult to impart physical properties as a container raw material,
A conductive yarn is driven into a partially non-conductive flat yarn as a replacement yarn or a yarn increase.

Here, since a general flexible container has a cylindrical side wall and static electricity may be generated on the entire surface, it is generally used that conductive filaments are regularly arranged at regular intervals. It is also preferable in terms of productivity. The conductive filamentous material may be arranged in a warp stripe type in which warp threads are driven at appropriate intervals, a weft stripe type in which warp threads are driven in at appropriate intervals, or a grid type in which both warp and weft threads are driven in at appropriate intervals. Since static electricity accumulates between the stripes of the conductive filaments, it is more effective if the spacing between the conductive filaments is narrower. This is even more effective because conduction is developed over the entire surface.

When static electricity is locally generated when a flexible container is formed by sewing or fusing the above-mentioned antistatic base cloth to actually fill and discharge the granular material, the generated charge is generated. Can be expected to have a substantial anti-static effect, but it is flexible in consideration of safety depending on the atmosphere such as low humidity where there is a danger of generating a lot of static electricity, the surrounding environment, and the type of filling contents. It is desirable to make a ground connection from the surface of the container base fabric to the metal stand or the ground, especially for electrically conductive thread-like objects that are driven in a grid pattern, because the ground connection at one location will prevent the entire surface from becoming electrostatically charged. is there.

[0013]

In the base fabric for an antistatic flexible container of the present invention, the conductive filaments are partially driven into the non-conductive flat yarn as the replacement yarns or the additional yarns. The base fabric for a flexible container has an excellent antistatic effect and can be produced by a conventional loom without affecting the weaving efficiency.

[0014]

EXAMPLES The present invention will be described in detail below with reference to examples.

As a thermoplastic synthetic resin, polypropylene (M
(FR = 0.8, melting point 145 ° C), extruded from a circular die with streaks at a melting temperature of 280 ° C, cooled to form a film,
Stretching temperature 145 ° C, annealing temperature 150 ° C, draw ratio 6 times, fineness 1,500 denier, tensile strength 5.3 by hot plate contact type stretching method
A flat yarn of g / d was obtained. As the conductive filament, select an organic conductive fiber (trade name Thunderon, fiber surface resistance value about 10 ¹ Ω / cm, strength 780 gf) in which copper sulfide is chemically bonded to acrylic fiber made by Japan Silkworm Dyeing Co., Ltd. 1, the warp flat yarn 1 and the weft flat yarn 2 are used as warp and weft at a weaving density of 15 × 15 / inch, and the conductive filaments 3 are added as stripes in a 100 mm, 150
Examples 1, 2 and 3 were prepared by driving in 100 mm intervals with a grid interval of 100 mm, and as a comparative example, a base fabric for a flexible container was produced in which only flat yarn was woven.

The base fabrics of Examples and Comparative Examples were rubbed with acrylic fibers, the electrostatic potential on the surface of the base fabric was measured, and an ash test was conducted to confirm the influence of the driving interval of the conductive filaments 3. The ash test is a simple test for visually observing the electrification, which is based on the fact that fine ash, such as lightweight ash, adheres to a charged substance. The results are shown in Table 1.

From Table 1, it can be seen that the base fabrics of the examples in which the electrically conductive filaments 3 are embedded have a lower electrostatic potential than the base fabrics of the comparative examples. Therefore, it was confirmed that the original fabric, which was punched in a grid pattern, was more suitable than the stripe pattern. In addition, ash was found to be attached to the base fabric of Example 2, but the amount was extremely smaller than that of the comparative example and was slightly attached to the vicinity of the middle of the stripe. This is because the conductive filaments 3 are widely spaced. It was confirmed that there was a part where the range of the antistatic function did not reach.
The base fabric of this example has a tensile strength of 150 kg / 5 cm or more in the longitudinal direction and 140 kg / 5 cm or more in the weft direction, and is one that conforms to the standards of the Japan Flexible Container Manufacturers Association one-way container, and its weaving efficiency is also conventional. It was about the same as the product.

[0018]

[Table 1]

Next, a flexible container having an inner bag 5 on the inside and a hanging hand 6 on the upper part was manufactured by using the base cloth 4 of these Examples and Comparative Examples, and static electricity at the time of filling and discharging the powder and granules was produced. And the antistatic effect were measured. The conditions are as follows. The state is shown in FIGS. 2 and 3. Bag size: φ1,250mm × 1,650mmH Inner bag: Polyethylene (without antistatic treatment) Filling amount: 900kg / bag Filling material: Low density polyethylene resin pellets (about φ3.0mm
Granular) Environment: Room temperature 13 ℃, Humidity 61-65% Measuring instrument: Digital electrostatic potential measuring instrument KSD-0102

Filling test (Fig. 2) At the time of emptying the flexible container, filling 450 kg of the above-mentioned resin pellet powder granules 7 and 900 kg, the measurement place is the upper surface of the bag (point A) on the base cloth 4 surface. , Middle part (point B), lower part (point C)
The amount of electrification at three points was measured, and the minimum and maximum amounts of electrification are shown in Table 2.

[0021]

[Table 2]

Discharge test (FIG. 3) A flexible container filled with powdery or granular material 7 made of resin pellets is transported to the upper part of the silo by a hoist using a lifting hand 6, at which time the bottom is opened as shown in FIG. The granular material 7 was discharged to the silo 8. The charge amount of the flexible container base fabric 4 was measured before, during, and after the discharge as in the filling test. After discharging, the charge amount (point D) of the inner bag 5 was added and measured, and the results are shown in Table 3.

[0023]

[Table 3]

From the results shown in Tables 2 and 3, in the examples of the present invention, the charge amount was remarkably reduced at the time of filling and discharging, and the antistatic property was imparted, as compared with the ordinary flexible container. I was able to confirm that. Further, in the present embodiment, the filler is a resin pellet, which itself has a low risk of ignition or explosion due to electrostatic discharge, but if the generation of static electricity is a safety hazard, the filler is filled. ,
It is preferable that the static electricity generated between the inner wall of the flexible container and the filling contents during the discharging operation be leaked by a ground connection.

[0025]

INDUSTRIAL APPLICABILITY The present invention is a base fabric for an antistatic flexible container provided with an antistatic function, in which a conductive yarn is present in a part of the warp and weft of a flat yarn woven fabric made of a thermoplastic synthetic resin. Therefore, it does not require a special device or process and can be manufactured at a relatively low cost using a conventional loom. In addition, an organic conductive fiber having a physical strength and texture similar to that of a synthetic resin thread is suitable for the loom so that the weaving machine is familiar and the weaving efficiency does not decrease.
In terms of antistatic property, the interval of driving the conductive filamentous material is 100 mm
In the case of the following, the antistatic effect is exhibited over the entire surface of the base fabric, and it is more effective if the conductive filaments are arranged in the warp and weft in a lattice pattern. Surface resistance of conductive filamentous material is 10
If it is ⁵ Ω / cm or less, it is sufficiently functional in the use of antistatic flexible container, and it is more effective in terms of safety if it is grounded during use.

[Brief description of drawings]

FIG. 1 is a partially enlarged plan view of an antistatic flexible container base fabric according to a third embodiment in which conductive thread-like materials are arranged in a grid.

FIG. 2 is a cross-sectional view of a flexible container at the time of a filling test of this example.

FIG. 3 is a cross-sectional view of the flexible container at the time of the discharge test of this embodiment.

[Explanation of symbols]

 1 Warp Flat Yarn 2 Weft Flat Yarn 3 Conductive Filament 4 Flexible Container Base Fabric 5 Inner Bag 6 Lifter 7 Powder Granules 8 Silo A Base Fabric Charge Upper Measurement Point B Base Fabric Charge Central Measurement Point C Base Fabric Charging Lower measurement point D Inner bag electrostatic charge measurement point

Claims (2)

[Claims] 1. A woven fabric obtained by weaving a flat yarn obtained by slitting and stretching a thermoplastic synthetic resin film, and a part of the flat yarn of the warp or the weft is stripped with a conductive yarn as a replacement yarn or a yarn increase. A base fabric for an antistatic flexible container, which is formed by driving in a grid shape or a lattice shape. 2. The conductive thread-like material has a fiber surface resistance value of 10 ⁰ to 10 ⁵
The base fabric for an antistatic flexible container according to claim 1, which is an organic conductive fiber thread having a strength of 500 gf or more at Ω / cm.