JPS60158699A - Laminated structure - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laminated structure formed by laminating different types of plastics, and more particularly to a laminated structure used as a housing member of an electronic device having an electromagnetic wave shielding function.

Conventionally, for example, in the case of housing members for electronic devices, a laminated structure consisting of a plastic layer and a conductive layer was created by thermally spraying metal such as zinc or applying conductive coating to the inner surface of the wall, which is mainly made of plastic. This shields the electronic device housed inside the housing from electromagnetic waves from the outside and from electromagnetic waves emitted from the inside.

However, in the conventional laminated structure as described above, the adhesion between the metal layer or conductive layer and the plastic layer is poor, causing problems such as peeling between the eyebrows and partial peeling. There were problems in that it was difficult to make it into a solid state, and its strength was also poor.

Also, the manufacturing method requires many steps,
Furthermore, there is a problem in that the cost is high because expensive thermal spraying or painting equipment is used.

The present invention aims to provide a laminated structure capable of solving the above-mentioned conventional problems.

The embodiments will be described below with reference to the drawings.

Reference numeral 1 in the figure is a housing to which the laminated structure according to the present invention is applied, and the main body 2 of this housing will be explained below in Figure 2.

The main body 2 has a double structure of an inner wall 3 and an outer wall 4 made of plastic, and has a hollow part 5 between the two walls. A plastic member 6 having electromagnetic wave shielding properties is interposed in the hollow portion 5 between the two walls. The outer peripheral wall of this plastic member 6 is welded to the outer peripheral parts of the inner wall 3 and the outer wall 4, respectively. On the other hand, the inner part of the plastic member 6 is welded to the inner wall 3 and outer wall 4 at different parts (Fig. 2), to the inner and outer walls 3 and 4 at the same position (Fig. 3), and to the inner and outer walls 3.4. They are firmly connected by welding (Fig. 4) at many positions.

The constituent materials of the inner and outer walls 3 and 4 have a volume resistivity of 1X
l0' ~ lXl0'' Ω・cm is the melt index (
ASTM-D-1238) is 0.01-1.5 g/l
thermoplastic, preferably 0.1-0.9g/10ml, such as polyethylene,
Polypropylene, polyvinyl chloride, acrylonitrile
Styrene copolymers, polyamides, ABS, polycarbonates, polyferene oxides, and modified products thereof,
It is a mixture. In addition, colorants, ultraviolet inhibitors,
Additives such as antistatic agents and charge-imparting agents may be mixed. By using a material with a high blow ratio, it is possible to almost faithfully reproduce the embossed pattern engraved on the mold with a depth of about 0.05 to 0.4 mm on the surface of the structure. A structure with uniform thickness can be obtained. In particular, the blow ratio (circular opening surface diameter of 30 mm and depth of concave recess with a diameter of 30 mm and depth of 3 mm held at the opening periphery of the concave recess and blow molding into the shape of the concave recess will not cause pinholes) Preferably, the material has a critical value (expressed as a ratio of depth of concave recess/diameter of opening surface) of 0.6 or more.

On the other hand, the plastic member 6 having electromagnetic wave shielding properties includes polyethylene, polypropylene, polyvinyl chloride, acrylonitrile-styrene copolymer, polyamide, A
B S1 polycarbonate, polyphelene oxide,
Alternatively, thermoplastics made of modified products or mixtures thereof are mixed with flakes, powders, or fibers of aluminum, nickel, iron, copper, zinc, tin, etc., or carbon fibers or glass fibers. The volume resistivity value of the plastic member 6 is lXl0-6~
l×10°Ω・cm, preferably 1×10 to lX
l0-''Ω·cm.

In addition, by welding thermoplastic films to both sides of the plastic member 6 in advance, during the molding process,
In particular, it is possible to reliably weld the peripheral edges.

Next, a method for manufacturing the above laminated structure will be explained with reference to FIGS. 5 to 8.

(1) Melt index 0.5g/10m1n on both sides
, Volume resistivity 7X1016Ω・cm Blow ratio 1.3
, polypropylene sheet AI with a thickness of 3 m rn.

A2 and 6 pieces of brass fiber with special surface treatment between them.
Volume specific resistance value of 0x4% mixture 2 x 10-3Ω・cm
Polypropylene sheets 1-B having a thickness of 2 mm are placed with a gap between them and their respective outer peripheries are gripped by clamps 7. (Fig. 5) (2) A heater 8 is inserted on both sides and between each side to preheat the sheet B and heat the sheets A, . . . A2 until they become plasticized. □, (3) Sheet AI, the heater 8 is removed in a state where AI is plasticized, and the distance between them is narrowed.

(4) Next, open the split molds 9a and 9b, and place the above seams FAI, AX, and B between them.

(5) Bringing the outer peripheral edges of sheets At, p, and B slightly closer together in the length direction to bend sheet AI, AI, and B, and introducing heated air between sheet AI and A. Preliminarily blow (Figure 6).

(6) Bring the molds 9a and 9b closer together.

(7) By closing the molds 9a and 9b, the sheet/
'+, the vicinity of the outer peripheries of Al and B are gripped with the pinch-off parts of the molds 9a and 9b. In this state, the outer peripheral edge of the sheet B is fused and joined to the sheets AI and A2 on both sides.

(8) Compressed air is sucked through the vacuum holes 1o provided in the cavity surfaces of the molds 9a and 9b, and compressed air is introduced between the materials, and molding is performed using positive and negative pressures (FIG. 7).

(9) After cooling, open the mold and take out the molded product.

(lO) Remove excess firmness from the outer periphery.

In the above manufacturing method, the seams (AI) and At on both sides are shown in Figure 8 (A
) may be used separated into two pieces as shown in
Further, as shown in FIG. 8(B), a cylindrical ballisson may be used in a flattened manner.

The present invention is as described above, and between the inner and outer walls 3 and 4 of the hollow double structure constituted by the inner wall 3 and the outer wall 4, which are made of thermoplastic and whose outer peripheral edges are welded to each other,
Since the plastic member 6 having electromagnetic wave shielding property is interposed and its outer peripheral part is welded between the inner and outer walls 3 and 4 to form a laminated structure, the plastic member 6 interposed between the inner and outer walls 3 and 4 By welding the plastic member 6 between the inner and outer walls 3 and 4 at its outer periphery, the plastic member 6 can be extremely firmly fixed to both walls 3 and 4 almost integrally. Furthermore, by connecting the plastic member 6 to the inner and outer walls 3.4 at its outer periphery, the plastic member 6 can be laminated uniformly and in a good laminated state up to the outer peripheral end portion of the laminated structure. Further, due to the above, the mechanical strength of the conventional hollow double structure can be significantly improved. The above-mentioned laminated structure is manufactured by forming thermoplastic sheets AI and A with gaps on both sides in the thickness direction of the sheet 16 having electromagnetic wave shielding properties.
i is placed to form a molding material, this molding material is placed between split molds 9a and 9b, and its outer periphery is formed into molds 9a, 9b.
While gripping and welding with the pinch-off part of 9b, the molds 9a,
At and Ax in the cavity of 9b are air-formed,
After that, the edge of the outer periphery that was gripped and welded at the pinch-off part was removed to produce the thermoplastic sheet A1. A laminated structure in which the sheet B is interposed between Ag3 can be formed at a low cost using almost the same method as ordinary pressure forming, and the thermoplastic sheets A+ and Ag are located on both sides of the seal I-B. The wall thickness after molding can be made almost uniform.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of a housing to which the present invention is applied; FIGS. 2 to 4 are sectional views showing main parts of different embodiments of the laminated structure according to the present invention;
The following figures show the steps of the manufacturing method of the present invention: Figure 5 is a clamping process diagram of the material, Figure 6 is a preliminary blowing process diagram,
FIG. 7 is a mold clamping molding process diagram, and FIGS. 8A and 8B are explanatory diagrams showing the form of the plastic sheet used. 3 is an inner wall, 4 is an outer wall, 6 is a plastic member having electromagnetic wave shielding properties, and 9a and 9b are molds. Patent applicant Kyoraku Co., Ltd. Figure 1 Figure 2 Figure 3 Figure 4 Figure 1i 1LJ SoD Figure 8 Δ1

Claims (1)

[Claims] A hollow double-walled structure made of thermoplastic plastic and composed of an inner wall and an outer wall whose outer peripheries are welded to each other, a plastic member having electromagnetic wave shielding properties is interposed between the inner and outer walls, and the A laminated structure characterized in that an outer peripheral portion is welded between the inner and outer walls.