Liquid transporting and storing container and manufacturing method for plastic-made inner container of transporting and storing container

The present invention is a liquid transport and storage container with a pallet-like pedestal made of metal or conductive plastic, four side walls, a bottom and top walls, a closed upper liquid inlet, and a bottom with an outlet. It has an inner container made of plastic erected on a pedestal with a side liquid outlet or an upper liquid outlet that can be closed, and an outer shell that surrounds the inner container, which is a metal or thin plate lattice. Consists of what consists of.

The plastic inner container of this type of liquid transport and storage container known in Patent Document 1 is a metal pedestal in order to prevent electrostatic charge on the surface of the plastic inner container due to the inner container rubbing against the metal outer shell during transportation. It has a permanent antistatic outer layer that serves as an electrical ground along with. Electric discharge due to spark formation between the plastic inner container and the metal lattice outer shell can cause flammable fillings in transport and storage containers and the ignition of explosive mixtures of gas and steam in enclosed spaces. It is said that this electric discharge is prevented in this way. When filling and emptying the inner container, and for example when stirring the liquid in the inner container for mixing purposes, the charge generated on the inner surface of the container and in the liquid by liquid friction is the permanent antistatic property of the plastic container. It cannot be escaped by this external ground by the outer layer.

The liquid transport and storage container described in Patent Document 2 is grounded by a grid covering made of thin metal wires placed on a plastic inner container, or by a conductive net or cloth attached to the inner container. As in the case of the transport and storage container known by Patent Document 1, only the electric charge appearing on the surface of the container is released by this external ground. In addition, electrical grounding of liquid containers with a grid hood, net or cloth is technically laborious and increases manufacturing costs accordingly.

In the liquid transport / storage container described in Patent Document 3, a ground portion is arranged in a take-out plug attached to the liquid discharge port of the inner container, and this ground portion is configured as a curved thin plate or a piece of metal. It extends over a partial area of the internal hole of the take-out plug and is connected to the pedestal of the container via mounting bolts and ground leads. Only the charge generated in the liquid due to the liquid friction is released by this internal ground. Further, in this liquid container, there is a risk that the ground portion is corroded by the liquid during transportation and storage of the corrosive liquid, and the electrical ground no longer functions.<patcit num="1"><text>German Patent Application Publication No. 19605890</text></patcit><patcit num="2"><text>German Patent Application Publication No. 19731518</text></patcit><patcit num="3"><text>German Patent Application Publication No. 19815082</text></patcit>

<p> An object of the present invention is to improve the above-mentioned liquid transport and storage container in consideration of reliable and comprehensive grounding of a plastic inner container and inexpensive production.</p>

<p> According to the present invention, the above problems are solved by the liquid transport and storage container having the characteristics of claim 1 and by the method for manufacturing a plastic inner container of the transport and storage container according to claims 12 and 13.</p><p> The dependent claims contain the advantageous and purposeful configurations of the present invention.</p>

<p> The strips made of conductive plastic material embedded in the non-conductive plastic material of the peripheral wall, bottom wall and top wall of the inner container of the transport and storage container have a thickness that matches the wall thickness of the inner container and are permanent. An electrical connection means is formed between the inner surface and the surface of the multilayer inner container having the antistatic outer layer, and thus the charge appearing in the liquid filling and the inner surface of the inner container due to the liquid friction is also transferred to the inner container and the metal outer shell. Charges that may be generated on the surface of the inner container due to the mutual friction of the inner container can also be released to the ground through the conductive strips on the peripheral wall, bottom wall and top wall of the inner container and the conductive pallet-shaped pedestal. Conductive strips made of plastic material have a strength lower than the strength of the base plastic of the inner container of the transport and storage container, and are not so loaded in the inner container manufactured by extrusion blow molding, for example, a blow molding die. It can be arranged on the dividing surface of the inner container, and thus the strength characteristics of the inner container are not impaired as a whole. An antistatic plastic material that is expensive to form a permanent antistatic outer layer of a plastic inner container that is originally made of a conductive strip and an inexpensive plastic material such as high density polyethylene, such as a conductive carbon black component. Limited use of high-density polyethylene containing it will only result in a slight increase in manufacturing costs. The electrical ground between the container surface and internal space of the plastic inner container and the liquid to be transported or stored inside it is for flammable liquids such as solvents, paints, varnishes and emulsions with a flash point of less than 35 ° C and emulsions. Allows the use of transport and storage containers as hazardous material containers and the use of containers in factory spaces where gas, steam or mist can create an explosive atmosphere.</p><p> The liquid transport and storage container according to the present invention is described below with reference to the drawings.</p>

This liquid transport and storage container 1, which can be used as a disposable container and a return container, has three main components, a front wall 3, a rear wall 4, two side walls 5, 6, a bottom wall 7 configured as a liquid discharge bed, and a screw. Intersects a top wall 8 with a liquid inlet 9 that can be closed with a lid 10 and a compatible rectangular inner container 2 made of polyethylene with a liquid outlet 11 with a take-out plug 12 on the underside of the front wall 3. A pallet-shaped pedestal 16 having an outer shell 13 composed of a metal vertical lattice stake 14 and a metal horizontal lattice stake 15 and a thin plate floor tank 17 for receiving a plastic inner container 2, and an inner container 2 It has two metal lids 18 for protection.

As FIG. 2 reveals, the front wall 3, rear wall 4, side walls 5, 6, bottom wall 7 and top wall 8 of the plastic inner container 2 manufactured by extrusion blow molding from high density polyethylene are the inner layer 19 and It consists of an intermediate layer 20 and a permanent antistatic outer layer 21 having a conductive carbon black component, and the conductive carbon black component is 10.⁵Ohm surface resistivity and 10³Guarantee the volume resistivity of Ohm. The thickness of the intermediate layer 20 is 1 to 2 mm, preferably 1.5 mm, and the thickness of the inner layer 19 and the outer layer 21 is 0.1 to 0.5 mm, preferably 0.2 mm.

For the production of the intermediate layer 20, recycled granules or pulverized products of pure polyethylene and / or polyethylene having a conductive carbon black component are used, and unused polyethylene granules are used as raw materials for the inner layer 19 and the outer layer 21. Will be done.

Figure 3 shows the 6-layer structure of the plastic inner container 2, which is an inner layer 19 made of pure high density polyethylene (HDPE) and polyamide (PA) or ethylene vinyl acetate copolymer (EVA). Shielding layer 32 for oxygen and hydrocarbon permeation and embedded in two primer layers 33, 34 consisting of and made of low density polyethylene (LLDPE) and recycled granules or pure high density polyethylene and / or conductivity. It includes an intermediate layer 20 made of crushed high-density polyethylene containing a carbon black component, and a permanent antistatic outer layer 21 made of high-density polyethylene containing a conductive carbon black component.

A conductive portion 23 composed of a strip 24 made of high-density polyethylene containing a conductive carbon black component is integrated with the main body 22 of the inner container 2, and these conductive portions 23 are the inner surface 25 of the inner container 2. It forms an electrical connection between the surface 26 and the surface 26, and their thickness matches the wall thickness 27 of the inner container 2. For clarity, the conductive strip 24, which appears bright in FIG. 1, extends vertically over the corner area 28 and / or the peripheral walls 3-6 between the peripheral walls 3-6 of the inner container 2 and the bottom wall 7 and the top wall. It extends diagonally over 8.

The screw-in lid 10 for closing the liquid inlet 9 and the take-out plug 12 of the inner container 2 can be made of conductive plastic, preferably high-density polyethylene having a conductive carbon black component.

The floor tank 17 of the pedestal 16 is fixed to the corner legs 29, the intermediate legs 20, and the leg frame 31 with a predetermined minimum ground clearance, and the floor tank 17 is used to transport the container 1 from four directions, such as a forklift truck. You can slide the gripping arm of. The legs 29, 30 and leg frame 31 are made of metal or conductive plastic, such as polyethylene with a conductive carbon black component, thus the transport and storage container 1 is the conductive strip 24 of the plastic inner container 2 and is permanently charged. Preventive It is electrically grounded via the outer layer 21, the outer shell 13, and the pedestal 16, which allows the charge that appears on the inner surface of the inner container, in the liquid filling, and on the surface of the container to escape.

When manufacturing the plastic inner container 2 for the transportation and storage container 1 First of all, a conductive material, especially a non-conductive base material in which strips made of high-density polyethylene having a conductive carbon black component are distributed around the periphery, particularly A multilayer tube-shaped premolded product made of high-density polyethylene is simultaneously extruded, and then this premolded product is blow-molded in a blow-molding mold to form an internal container.

Another method for producing the plastic inner container for the liquid transport and storage container is to simultaneously extrude a multi-layer tubular premolded product and surround it with a material tube that continuously or discontinuously advances from the extrusion head. Distribute and divide, inject conductive plastic into the gap space to form strips, weld the strips evenly with the tubular premolded product, and blow mold the preformed product in the blow molding mold. It is characterized by being an internal container.

<figref num="1">It is a perspective view of a transport and storage container.</figref><figref num="2">The wall portion of the plastic inner container of the transport / storage container having a three-layer structure is shown in an enlarged perspective view.</figref><figref num="3">The partial cross section of the inner container having a 6-layer structure is shown in an enlarged view.</figref>

Code description

1 Liquid transport and storage container 2 Inner container 3 Front wall 4 Rear wall 5, 6 Side wall 7 Bottom wall 8 Top wall 19 Inner layer 20 Intermediate layer 21 Outer layer 24 Strips 32 Shielding layer 33, 34 Primer layer