JP3072448B2 - Method of manufacturing electromagnetic wave shield panel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an electromagnetic wave shielding panel used for a housing of an electric device, a wall material for a building, an electromagnetic wave shielding material of a measuring instrument, and the like.

[0002]

2. Description of the Related Art Conventionally, metal panels are often used as panels constituting a housing of an electric device. However, metal panels require a large number of processing steps such as pressing, bending, and welding parts. There are problems that it takes time and cost to finish such as painting, and there are many restrictions in terms of design. For this reason, the constituent materials of the housing panel are shifting from metal to resin. In other words, resins are lightweight and excellent in moldability, have a large degree of freedom in design, are capable of integrating components, are advantageous in terms of cost, etc. It is widely used for molded parts and the like, and its application is being expanded more and more. However, even though resin is excellent as a cord material, it is inferior in electromagnetic wave shielding properties. Therefore, (1) a method of applying a conductive paint to the surface of the resin panel with a spray gun, and (2) a method of applying a conductive paint to the surface of the resin panel. Means for imparting electromagnetic wave shielding properties are required, such as a method of attaching a metal foil and (3) a method of forming a panel with a composite resin mixed with a conductive filler. The coating method of (1) has a problem that the coating work environment is poor and that the coating film is peeled off by an external impact to adversely affect peripheral devices. In the method (2) for attaching a metal foil, when the panel has a three-dimensional shape, the attaching operation is difficult. In the method (3) of molding a panel with a composite resin, it is difficult to simultaneously satisfy the electromagnetic wave shielding property and the moldability of the panel itself. As an improvement of the coating method of (1), the applicant has disclosed in Japanese Patent Application Laid-Open No. 61-197.
As disclosed in Japanese Patent Publication No. 221, a molded article having a hollow double-walled structure is formed by placing a parison in a mold and performing blow molding, and thereafter, a paint is filled in the molded article in the mold. We have proposed a method for manufacturing a molded product with electromagnetic shielding properties by forming a conductive coating on the inner surface of the hollow part of the molded product.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The molded article manufactured according to No. 7221 has a conductive coating film formed on the inner surface of the hollow portion of the hollow double-walled structure, and is always protected against external physical and chemical influences. For this reason, there is an effect that a good electromagnetic wave shielding property is maintained, but it has the following problems. That is, in the above-mentioned manufacturing method, since the coating operation of the paint is performed while the hollow panel is still in the mold during molding, the paint having a relatively low temperature is provided in the hollow panel having a high temperature. As a result, the hollow panel is rapidly cooled and deformed. On the other hand, there is a coating method in which the hollow panel is removed from the molding die and then the paint is filled, applied, discharged, and dried in the hollow panel.However, the paint is simply removed from the hollow panel through the opening of the hollow panel. If filling, coating, discharging, and drying of the paint are performed, the paint is likely to adhere to the vicinity of the opening, and it is difficult to remove the paint film that has once adhered, thereby increasing the defective rate in the manufacturing process. was there.

The present invention has been made in view of the above, and it is possible to discharge a surplus paint easily and in a short time at the time of applying a paint without deforming a hollow panel, and to obtain a stain on a paint. It is another object of the present invention to provide an electromagnetic wave shield panel which can prevent the occurrence of the electromagnetic wave.

[0005]

In order to achieve the above object, a method of manufacturing an electromagnetic wave shielding panel according to the present invention comprises:
After molding a plastic panel having a hollow double-walled structure in which the cylindrical portion is integrally formed and taking it out of the molding die,
A paint having an electromagnetic wave shielding property is injected from an opening hole provided in a tubular portion of the panel, then excess paint is discharged, dried, and the tubular portion is cut off from a base end.

[0006]

[Operation] A panel molded into a hollow double-walled structure is taken out of a molding die and cooled, and a paint is injected into the hollow interior from a cylindrical portion. The injected paint is applied to the entire inner wall. At this time, the remaining paint is discharged from the opening of the cylindrical portion.

[0007]

[Embodiment] An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an electrophotographic copying machine. Since electromagnetic waves are radiated from a copying operation section of this type of copying machine, an electromagnetic wave shielding panel 1 is provided on a panel covering the front side to protect workers from the electromagnetic waves. Is used. This electromagnetic wave shield panel 1 (hereinafter abbreviated as a shield panel) has a structure in which a paint having an electromagnetic wave shielding property is applied to the inner surface of a plastic hollow panel.

Hereinafter, a method of manufacturing the shield panel 1 will be described. (1) Forming Step As shown in FIG. 2, the shield panel 1 is formed by blow molding by sandwiching a plasticized and melted parison between split molds 2 and 3 having cavities formed in an outer shape thereof. You. After the molding, the mold is cooled and then opened to take out. At one end in the longitudinal direction of the shield panel 1, there is provided a tubular portion 4 communicating with the hollow interior of the shield panel 1. After the molding, the tip of the cylindrical portion 4 is cut off to form an opening hole.

(2) Filling and coating process As shown in FIG. 3A, the shield panel 1 is placed upright with the cylindrical portion 4 facing upward, and the shield panel 1 is connected to the nozzle 6 connected to the injection machine 5 through the opening hole of the cylindrical portion 4. Paint 7 having an electromagnetic wave shielding property. The injection amount at this time is sufficiently small with respect to the hollow volume of the shield panel 1, for example, about 1/4 to 1/3. Next, the shield panel 1 is turned around. Thereby, the paint in the hollow moves in the hollow and is applied to the entire inner surface thereof. Thereafter, as shown in FIG. 3B, the surplus paint is turned upside down and discharged from the opening into the receiving container 8 connected to the filling machine 5. 9
Denotes a filter and 10 denotes a paint tank. In the filling and application steps, the paint may be forcibly discharged from the nozzle 6 after filling the inside of the shield panel 1 with the paint.

(3) Drying Step After that, the coating film on the inner surface of the hollow is dried by means such as leaving it to stand or blowing dry air through an opening hole. Fig. 3 after drying
As shown in FIG. 3 (c), the slanted base end of the cylindrical portion 4 is cut off, and the opening formed by this is cut into the cap 1.
Seal with 1. Note that the cap 11 is not always necessary. The resin used in the present invention is a blow-moldable thermoplastic resin such as ABS resin, polycarbonate, polyamide, and modified polyphenylene oxide. As a coating material, nickel, copper, silver, and a resin-based binder such as acrylic and polyurethane are used. A water-based or oil-based paint containing a conductive filler such as carbon graphite or carbon black can be used. The thickness of the blow-molded resin is preferably about 2 to 4 mm, and the thickness of the coating film is preferably about 30 to 80 μm.

[0011]

According to the present invention, the shield panel 1 to be blow-molded is taken out of the dies 2 and 3 and cooled sufficiently, and then the paint is filled in the hollow portion thereof. Deformation can be prevented. Also,
The filling and discharging of the paint is performed by the cylindrical portion 4 integrally formed with the shield panel 1.
Even if the paint adheres to the vicinity of the opening hole of the shield panel 1 because the other members are easily attached, the shield panel 1 is finally cut off from the base end of the tubular portion 4, so that the stain of the shield panel 1 itself can be prevented from being stained by the paint. The defective rate in the process can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of use of an electromagnetic wave shielding panel manufactured by the method of the present invention.

FIG. 2 is a cross-sectional view showing a forming process of the hollow panel.

FIGS. 3 (a), (b) and (c) show the injection and discharge of paint,
It is explanatory drawing which shows each process of sealing.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electromagnetic wave shield panel, 2, 3 ... Split mold, 4 ... Tube part, 5 ... Injector, 6 ... Nozzle, 10 ... Paint tank, 11
…cap.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H05K 9/00

Claims (1)

(57) [Claims] 1. A plastic panel having a hollow double-walled structure in which a cylindrical portion is integrally formed, taken out of a molding die, and provided with an electromagnetic wave shielding property from an opening provided in the cylindrical portion of the panel. A method for manufacturing an electromagnetic wave shielding panel, comprising: injecting a coating material, discharging surplus coating material, drying, and cutting off a cylindrical portion from a base end.