JPS6137670Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a plastic container that is highly conductive, lightweight, and has excellent cushioning properties.

[Conventional technology]

Traditionally, containers made of metal, which has excellent conductivity, have been used for purposes such as protecting semiconductor materials such as MOS ICs, preventing noise generation in electronic equipment, packaging precision parts, and shielding radio waves. BACKGROUND OF THE INVENTION Containers or containers made of a mixed material of an electrically conductive material and a plastic material are known.

[Problem that the invention attempts to solve]

Conventional metal containers are heavy and inconvenient to transport. In addition, conventional conductive plastic containers are lighter than metal containers, but when providing a storage recess with an appropriate uneven shape to properly protect semiconductor materials, etc., the unevenness Because the thickness of the conductive plastic wall varies depending on the shape, the conductive substance contained in the mixed material is not uniformly dispersed in the plastic material during injection molding, etc., and the conductive material on the surface forming the storage recess etc. This has the disadvantage that the conductivity is not constant and a container having the desired conductivity cannot be obtained.

The present invention was devised in view of the above-mentioned drawbacks, and the object is to provide a plastic container that is lightweight and can provide uniform conductivity.

[Means for solving problems]

The present invention relates to a plastic container which has a hollow double wall structure with a storage recess formed therein, and whose inner and outer walls are made of a conductive plastic material.

In this invention, plastic containers are containers, cases, tanks, etc. used for applications that require conductivity or that require prevention of static electricity hazards (electrostatic attraction, electrostatic repulsion, electrostatic induction, discharge, electric shock). This includes housings. Furthermore, the conductivity of the plastic container according to the present invention is 10 ^-1 to 10 -1 in terms of surface resistivity.
The value is 10 ¹² Ω·cm, preferably 10 ² to ^{10 8} Ω·cm, and can be arbitrarily set depending on the purpose, size, etc. The inner and outer walls are made of a conductive plastic material made by mixing a thermoplastic material such as polyethylene, polypropylene, polyamide, polyvinyl chloride, ethylene-vinyl acetate copolymer, or polystyrene with a conductive substance such as carbon. .

[Effect]

In general, for containers etc. that are integrally molded by injection molding or the like using a conductive plastic material made by mixing a conductive substance into the plastic material, the flow of the material changes as the cross-sectional area changes, and the material is relatively thick. The concentration or arrangement direction of the conductive substance contained in the conductive plastic material tends to change between different parts and thinner parts, and between parts near and far from the injection gate. Uniformity occurs. In particular, the above-mentioned drawbacks have been noticeable in containers that have an appropriate uneven shape to properly protect semiconductor materials and the like. In contrast, in the case of the present invention, even if the container has a storage recess formed inside, the inner wall that makes up the storage recess is almost divided by the outer wall that makes up the outer shape and the hollow part, and the inner wall and the outer wall Each has a substantially uniform wall thickness. That is,
A conductive plastic material made by mixing a conductive substance into a plastic material has substantially uniform inner and outer walls with uniform conductivity, and is suitable for use as a plastic container for storing semiconductor materials and the like.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, reference numeral 1 denotes a plastic container according to the present invention, which is constructed by connecting a main body 2 and a lid 3 with a hinge 4. At least one of the main body 2 and the lid 3 is formed into a hollow double wall, and 5 is an inner wall, 6 is an outer wall, and 7 is a hollow part. 8
is a recess formed inside for storage of stored items,
By configuring the inner wall 5 in accordance with the external shape of the stored item, it can be formed into an appropriate shape.

Further, 9 is a mating surface between the main body 2 and the lid 3, and 10 is a welded part where the inner surfaces of the inner wall 5 and the outer wall 6 are welded together.

The inner wall 5 and outer wall 6 are made of polyethylene, polypropylene, polyamide, polyvinyl chloride, ethylene-
It is made of a material made by mixing a thermoplastic such as vinyl acetate copolymer or polystyrene with a conductive substance such as carbon.

A specific example is shown below.

Using an extruder with a screw diameter of 65 mm, a pellet-like compound containing 40 parts by weight of carbon black and 100 parts by weight of medium-low pressure polyethylene was mixed.
Melt and knead at a set temperature of 200℃ and extrude a parison with an outer diameter of 200mm and a wall thickness of 3mm. Then, the parison is closed using a split mold, and 7 kg/kg is placed inside the parison.
Blow in cm ² of compressed air and form into the shape of a cavity. After the molded product is cooled and taken out from the mold, excess casting flash is removed, and a hollow double-walled structure consisting of a main body and a lid, measuring 220 mm long, 200 mm wide, 80 mm high, and 758 g in weight, is formed as shown in Figure 1. Got a wall case. The surface resistivity of the obtained case was 7.3×10 ⁴ Ω·cm.

As shown in the above specific example, in order to manufacture the plastic container 1 according to the present invention, in addition to manufacturing the plastic container 1 integrally by blow molding, other methods include vacuum molding, injection molding, and compression molding for the inner wall and outer wall, respectively. Although it is possible to mold them and then combine them, blow molding is preferable to obtain the plastic container of the present invention because it can be manufactured in one piece and the conductive properties do not deteriorate because the inner and outer walls are connected as one unit.

In the plastic container 1 of the present invention, the semiconductor material such as an IC stored in the storage recess 8 is placed on the inner wall 5.
Since the semiconductor material is in contact with the semiconductor material itself, it does not become electrically charged, and even if the semiconductor material is electrically charged, the inner wall 5 and the outer wall 6 are connected to each other at the mating surface 9, so that dielectric energy is easily transferred to the outside. The functions of stored items such as semiconductor materials are not affected by the charging. By appropriately selecting the mixing ratio of the conductive material to the thermoplastic plastic and the type of the conductive material, desired conductivity can be obtained depending on the application. In addition, the plastic container 1 is made of plastic with low specific gravity and has a hollow double-walled structure, so it is much lighter than conventional metal containers, and has excellent cushioning effects to protect stored items. There is.

As an embodiment of the present invention, when obtaining a plastic container with excellent conductivity, light weight, and excellent cushioning properties, 5 to 70% by weight of carbon, which is made by specially treating the particle surface of polyolefin such as polyethylene, is preferably 10 to 40% by weight. It is preferable to blow mold a plastic material obtained by mixing % by weight to integrally construct a hollow double-walled container having an inner wall 5 and an outer wall 6, from the viewpoint of mass production and low cost.

FIG. 3 is an enlarged sectional view of a container wall showing another embodiment, in which the inner wall 5 and the outer wall 6 are made of surface layers 5a and 6a made of a plastic material imparted with conductivity and a plastic material not imparted with conductivity. It is composed of main layers 5b and 6b. The structure shown in FIG. 3 can be obtained, for example, by co-extruding a two-layer parison consisting of a surface layer and a main layer, and blow-molding the parison by closing it in a split mold consisting of a convex cavity and a concave cavity. In this case, the main layer can compensate for the decrease in blow moldability of the surface layer made of conductive plastic material, and also reduce the need for relatively expensive conductive plastic material. Moreover, the surface resistivity can be maintained at approximately the same value as that of the container wall shown in FIG.

As described above, the plastic container of the present invention has a hollow double wall structure with a storage recess formed inside, and the inner and outer walls are made of conductive plastic material, so it can protect semiconductor materials and protect electronic equipment. Desired conductivity can be obtained depending on the application such as noise prevention, precision parts packaging, radio wave shielding, etc., and it also has practical effects such as being lightweight and having excellent cushioning properties.

[Effects of the invention] As described above, the present invention is a container that is lighter and easier to transport than conventional metal containers or conductive plastic containers, and has a more constant electrical conductivity than conventional conductive plastic containers. can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway perspective view of a plastic container according to the present invention, Fig. 2 is an enlarged sectional view of the wall of the same container;
FIG. 3 is an enlarged sectional view of a container wall showing another embodiment. 1...Plastic container, 2...Main body, 3...
Lid body, 5...Inner wall, 6...Outer wall, 7...Hollow part.

Claims (1)

[Scope of utility model registration request] 1. A plastic container comprising a hollow double-walled structure with a storage recess formed therein, and comprising an inner wall and an outer wall made of a conductive plastic material.