JPH026712B2 - - Google Patents

Description

[Detailed description of the invention]

Conventionally, polyvinyl chloride resin (hereinafter referred to as PVC)
is ethylene-vinyl acetate copolymer resin (hereinafter referred to as EVA)
Flexible containers are used to transport and store powders, etc., but static electricity can be discharged when the contents are injected or discharged, or when the flexible containers containing powder are moved for transportation or storage. When working in a solvent atmosphere such as when handling special contents, there is a risk of explosion or fire caused by static electricity discharge, so be careful not to generate static electricity. Measures to prevent this are urgently needed, and there is a strong need for flexible containers that prevent static electricity. To solve these problems, conductive tarpaulin has been developed, and flexible containers using this conductive tarpaulin are considered. For example, (1) Tarpaulin with an antistatic agent coated or printed on the surface of the sheet. (2) Tarpaulin with antistatic agent kneaded into resin. (3) Tarpaulin made of resin mixed with conductive material such as carbon black. (4) A tarpaulin that uses conductive material for the cloth material that is the base material of the sheet. etc. have been considered. However, these tarpaulins had the following drawbacks. (1) A tarpaulin whose surface is coated or printed with an antistatic agent has a problem in that its antistatic effect deteriorates over a short period of time due to moisture or surface friction. (2) Tarpaulin with antistatic agent mixed into resin
Although the durability of tarpaulin (1) has been improved, the antistatic agent is still washed away when it comes into contact with water, and there are significant restrictions on the type and amount of antistatic agent added in terms of moldability. The surface will not get dirty as well. (3) Tarpaulin made by kneading a conductive material such as carbon black into resin requires a large amount of carbon black to be added, which not only compromises the strength of the resin, but also makes it expensive and only available in black. It is. (4) Tarpaulin, which uses a conductive material for the cloth material that is the base material of the sheet, is not versatile because the cloth is special. It had drawbacks such as: In order to improve these shortcomings, the inventors of the present invention have conducted intensive research and found that by using a tarpaulin having a conductive layer in the middle layer, the inlet port 1 and the outlet port 2 have a conductive layer in the inner layer (intermediate layer). The connection parts of the flexible container main body 3 and the conductive hanging belt 4, each having a conductive layer (layer), are sewn using conductive sewing thread 7 or are connected by using metal caulking, and are further conductive. A conductive rope 6 is attached to a metal hanging fitting 5 such as a ring attached to the tip of a conductive hanging belt 4.
By hanging the conductive rope 6, the metal hook 9 that is hung by being hooked to the conductive rope 6 is connected to all parts of the flexible container through the conductive layer, which is an innovative and highly safe method. This led to the invention of a flexible container that prevents static electricity. The flexible container that prevents charging according to the present invention will be described in detail below. In the tarpaulin used in the present invention, a conductive layer is provided by coating or printing a conductive paint containing highly conductive carbon black on a base fabric, and a resin such as polyvinyl chloride is coated on both the front and back sides with this conductive layer in between. Or a laminated tarpaulin with a resin layer, in which rod-shaped electrodes with a diameter of 1 m/m and a length of 1 cm are placed parallel to each other at a distance of 1 cm so as to contact the conductive layer constituting the intermediate layer of the tarpaulin. Use one whose value when placed and measured is 10 ⁸ Ω or less. (The unit of electrical resistance value at this time is Ω/1cm×1
expressed as cm). Even by simply using this conductive tarpaulin, a considerable antistatic effect can be obtained due to the corona discharge phenomenon from the terminal portion of the tarpaulin. However, in the present invention, when considering various usage conditions,
In order to make it even safer, we succeeded in further increasing safety by disconnecting the ground from the flexible container as described below. That is, in the present invention, a tarpaulin having a conductive layer as an intermediate layer is used to construct an input port 1, an outlet port 2, and a flexible container body having a conductive layer as an inner layer (intermediate layer). 3. Each connection part of the conductive suspension belt 4 is connected by sewing with conductive sewing thread or using metal caulking, and a ring etc. is attached to the tip of the conductive suspension belt 4. By hooking the conductive rope 6 to the metal hanging fitting 5, the metal hook that is hung by the conductive rope 6 and all parts of the flexible container are made of a conductive layer. This allows for easy grounding from the metal hook 9, making it an extremely safe flexible container that can prevent shocks to workers, explosions, and fires caused by static electricity. can be obtained. Conductive suspension belt 4 used in the present invention,
and the conductive hanging rope 6 is a mixture of conductive materials such as conductive fibers and has an electrical resistance value of 10 ⁸ Ωcm or less (preferably, 10 ⁶ Ωcm or less is used), The surface layers of the belt and rope are also conductive. At this time, if necessary, the surface of the rope may be protected by wrapping an insulating material such as PVC tape around the part of the hanging rope other than the part that contacts the metal hanging fitting 5 and the metal hook. good. In addition, the conductive layer is exposed to the outside air without covering the conductive layer with an insulating layer. state. The antistatic effect due to corona discharge from this exposed portion is very large. A comparison of charging tests between the flexible container according to the present invention and conventionally used flexible containers will be shown below based on Examples. Example: A 1000D polyester woven fabric is used as the tarpaulin for the main body, and the inner layer has an electrical resistance of 3.0×10 ⁴ Ω/1cm.
Prepare a 1 mm thick PVC tarpaulin with a 1 cm x 1 cm conductive layer. Next, a 500 d polyester woven fabric was used as a tarpaulin for the inlet and outlet, and a PVC tarpaulin with a thickness of 0.52 mm and having a conductive layer with an electrical resistance of 3.8×10 ⁴ Ω/1 cm×1 cm as an inner layer was prepared.
In addition, the hanging belt and hanging rope comply with JIS standard Z-
1651, the electrical resistance of the suspension belt and suspension rope itself is 10 ³ Ω/1cm or less, and the suspension fittings are JIS standard Z-
Use a material that complies with No. 1651 and has a resistance of 1 Ωcm or less. Sewing using these materials has an electrical resistance of 10 ³
Capacity 1250 sewn with conductive sewing thread of Ω/cm or less
To prevent water leakage or infiltration from the perforated holes, we prepared a 0.5 mm thick soft PVC film heat-sealed to the sewn part and covered it with non-conductive PVC tarpaulin. A chargeability comparison test was conducted with a regular square flexible container containing 1250. Experiment 1 The flexible container of this example and the normal flexible container were each filled with 1 ton of nylon chips and hung with metal hooks.
Metal hooks shall be insulated. Next, after opening the discharge port and taking out the contents, the electrostatic voltage at each part of each flexible container was measured, and the results were as shown in the attached table. Experiment 2 In Experiment 1, the metal hook was grounded to obtain grounding, and the other operations were the same, and the charged voltage at each part of each flexible container was measured. The results are shown in the attached table.

【table】

【table】 [Brief explanation of drawings]

FIG. 1 is a perspective view of a square container, and FIG. 2 is a partially cutaway sectional view of the square container. DESCRIPTION OF SYMBOLS 1... Input port, 2... Outlet port, 3... Main body, 4... Conductive hanging belt, 5... Hanging fittings, 6... Conductive rope, 7... Conductive sewing thread, 8... Conductive tarpaulin terminal part, 9... Metal hook, 10... conductive layer of tarpaulin inner layer.

Claims (1)

[Claims] 1 The intermediate layer has conductivity and the electrical resistance is 10 ⁸ Ω/
A flexible container made of tarpaulin with a size of 1 cm x 1 cm or less, wherein a conductive container hanging belt made of a conductive material is attached to the main body of the flexible container, which has a contents input port and a contents discharge port. The electrical resistance between the metal hook and the end of the flexible container body is 10 ⁸ Ωcm or less when the flexible container body is suspended from a metal hook via a conductive rope or the like. A flexible container that prevents static electricity.