JPS61205110A - Manufacture of electromagnetic wave shielding molded article - Google Patents

Abstract

PURPOSE:To establish the title method wherein, in molding an electrically-conductive composite sheet, neither an electrically-conductive composite sheet is spoiled nor an electrically-conductive layer is broken, by making use of the electrically-conductive sheet obtained by sandwiching a ultraplastic alloy sheet in between thermoplastic synthetic resin sheets. CONSTITUTION:An electrically-conductive composite sheet is amde to unify with the surface of a molded article, by a method wherein the electrically-conductive composite sheet, on both sides of which thermoplastic synthetic resin sheets have been laminated and stuck respectively, is molded on the inside of a ultraplastic alloy sheet through air-pressure forming by making use of a female mold which is a movable mold of the inside of an injection molding device, then mold clamping is performed while the molded electrically-conductive composite sheet is being left behind in the female mold as it is and molding is performed by injecting molten resin within a cavity between the female mold and a male mold. As for the ultraplastic alloy sheet, it is a Pb-Sn alloy, Pb is 35-40wt%, Sn is 65-60wt% and grain diameters of the metals each are 4-6mu. Manufacture of the sheet is performed through a rolling method and as for a thickness of the sheet, it is desirable to make the same itooan extent of 50-100mu.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for efficiently manufacturing a molded product with excellent electromagnetic shielding properties.

Conventional technology Conventionally, molded products with excellent electromagnetic shielding properties have been made using conductive sheets manufactured by coating conductive paint, metal arc welding, vacuum evaporation, plating, and kneading conductive filler. There is a method in which the conductive sheet is preformed in a mold to create an approximate shape, and the preformed conductive sheet is placed in the mold of an injection molding machine to perform molding. However, with this method, there are problems such as the conductive layer breaking when molding the conductive sheet or during injection molding, and the conductive coating flowing at the gate part due to the resin temperature during injection molding. There it is,
It is difficult to obtain the desired electromagnetic wave rolling property, and since the preforming mold and the injection mold are different molds, it is difficult to obtain the desired electromagnetic wave shielding property, and since the preforming mold and the injection mold are different molds, the sheet must be preheated and in close contact with the mold. Injection molding cannot be performed, and the conductive layer may break due to thermal shock and pressure shock during injection molding.

Problems to be Solved by the Invention Therefore, the present invention solves the drawbacks of the prior art,
The purpose of this invention is to provide a method for producing molded products with high conductivity without any problems.

Means for Solving the Problems In the present invention, a superplastic alloy sheet with thermoplastic synthetic resin sheets laminated and bonded on both sides is used as the conductive sheet, and the conductive sheet is preformed by setting it in an injection molding machine. By using a female mold that has been molded, the drawbacks of the conventional techniques as described above are overcome.

That is, the present invention provides the following methods: ``A conductive composite sheet in which a thermoplastic synthetic resin sheet is laminated and bonded to the inner surface of a superplastic alloy sheet is molded by air pressure molding using a female mold that is a movable mold in an injection molding device. Then, the molded conductive composite sheet is placed in the female mold and the mold is closed, and then molten resin is injected into the cavity between the female mold and the male mold to perform molding.
The main idea is "a method for manufacturing a molded product that is resistant to electromagnetic waves," which is characterized by integrating a conductive composite sheet onto the surface of the molded product.

The conductive composite sheet used in the present invention is a superplastic alloy sheet with thermoplastic synthetic resin sheets laminated and bonded on both sides.

In the above, the superplastic alloy sheet is Pb-Sn
Alloy, especially Pb: 35-40% by weight, Sn: 65-60
Weight: 1%, particle size of each metal: 4-6μ (preferably 5μ)
It is. Sheets are made by rolling, and the thickness of the sheets is set at 50 mm in consideration of drawability, price, and electromagnetic shielding effect.
It is preferable to set it to about 100μ. An alloy or metal sheet other than the Pb-Sn alloy may be used as long as it has conductivity and draw formability.

As a thermoplastic resin sheet, the temperature at the time of drawing molding (100
~200℃), considering the suitability of injection resin, acrylic, AB
S, polycarbonate, polyamide, polyvinyl chloride,
It is best to use a sheet of synthetic resin such as polyethylene, polystyrene, polypropylene, polyacetal, ethylene-vinyl acetate copolymer, etc., and the thickness is 0.311 mm.
~0.6 mm, and the thickness may be appropriately selected depending on the depth of molding and the like.

As the adhesive constituting the adhesive layer for adhering the superplastic alloy sheet and the front and back thermoplastic synthetic resin sheets, acrylic resin-based or rubber-based adhesives can be used.

The conductive composite sheet described above is not preformed using a mold, wooden mold, etc. that is separate from the injection molding machine, but is installed inside the injection molding machine (for example, as described in Japanese Patent Publication No. 50-19132). Preliminary molding is performed using a mold for injection molding.

At this time, the female mold is preferably heated to about 80°C,
Using a heated platen to heat the conductive composite sheet, heat the platen at a temperature of 170°C for about 30 seconds, and after heating,
It is best to send it into a female mold and form it by pressure air, for example, at a pressure of 3.
1. Mold for 15 seconds.

Next, the heating platen is returned to the outside of the mold, the mold is closed with the molded conductive composite sheet placed inside the female mold, and then molten resin is injected into the cavity between the female mold and the male mold. Perform molding.

As the resin to be melted and injected, thermoplastic resins such as ABS, acrylic, polycarbonate, polyimide, polyvinyl chloride-polyethylene-polystyrene-polypropylene, polyacetal, etc. can be used, and adhesiveness with the conductive composite sheet is considered. and select.

When injection molding is performed in this way, the conductive composite sheet placed in the female mold after pre-molding is integrated with the injected resin, and the conductive composite sheet is placed on the surface along the shape of the molded product. An integrated molded product is obtained.

Effects and Effects According to the method of the present invention, 1. Since a conductive composite sheet in which a superplastic alloy sheet is sandwiched between thermoplastic synthetic resin sheets is used, the conductive composite sheet is not damaged during molding. Moreover, since the injection mold installed in the injection molding machine is used for preforming the conductive composite sheet, the temperature of the conductive composite sheet can be controlled appropriately, and the conductive composite sheet remains in close contact with the mold. Since it can be injection molded, the conductive layer does not break, allowing efficient manufacturing.

The example conductive composite sheet is ABS (thickness 0.3M)/
Superplastic alloy sheet (thickness 9Q)/ABS (thickness 0.
First, a conductive composite notebook was heated for 30 seconds using a heating plate heated to 170°C.
After heating, the conductive composite sheet was fed into a female mold whose temperature was controlled to 80° C., and pre-molded under conditions of a pressure of 31 and a time of 15 seconds.

After preforming, the heating plate is returned to the outside of the mold, and the mold is clamped.
ABS resin (manufactured by Denki Kagaku Kogyo, Denka QF) at 230℃
The molded product was obtained by injection at a temperature of 30 seconds and cooling for 30 seconds.

The obtained molded product exhibited excellent electromagnetic shielding properties, with no breakage of the conductive composite sheet or its inner superplastic alloy sheet.

Claims (1)

[Claims] (1) A conductive composite sheet in which thermoplastic synthetic resin sheets are laminated and bonded on both sides of a superplastic alloy sheet is molded by air pressure molding using a female movable mold in an injection molding device, and then molded. The mold is closed with the conductive composite sheet placed inside the female mold, and then molten resin is injected into the cavity between the female and male molds to form a conductive composite sheet on the surface of the molded product. A method for manufacturing an electromagnetic shielding molded product, characterized by integrating a composite sheet.