JP3072447B2 - 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 material, it is inferior in electromagnetic wave shielding properties. Therefore, (1) a method of applying a conductive paint to the surface of a resin panel with a spray gun, and (2) a method of coating a metal surface with a metal Means for imparting electromagnetic wave shielding properties are required, such as a method of attaching a 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]

In the above-mentioned conventional manufacturing method, the coating operation is performed while the hollow panel is still in the mold during the molding, so that the hollow panel having a high temperature is still in operation. However, there is a problem that the hollow panel is rapidly cooled and deformed due to the injection of a relatively low temperature paint.

[0004] On the other hand, there is a coating method in which the hollow panel is removed from a molding die and then the paint is filled, applied, discharged and dried in the hollow panel. However, the coating is simply performed after the hollow panel is removed from the die. However, there is a problem that it is difficult to obtain a uniform coating film on the inner surface of the hollow panel with the coating method, and that it takes a long time to fill, apply, and discharge the coating to the hollow panel.

The present invention has been made in view of the above, and provides a method of manufacturing an electromagnetic wave shielding panel in which the hollow panel is not deformed, the working time is short, and the inner surface of the hollow panel can be uniformly applied. It is intended to provide.

[0006]

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 and removing it from a molding die, a paint having an electromagnetic wave shielding property is injected into an area near the opening in the panel through an opening provided at one end of the panel. Then, a nozzle tube is inserted from the opening hole to the inner bottom of the hollow, and the excess paint in the panel is sucked and discharged by the nozzle tube. Thereafter, the coating film adhered to the inner wall of the hollow portion of the panel is dried. Further, in the above-described method for manufacturing an electromagnetic wave shield panel, the panel is placed in an upright state, paint is applied and applied to the panel, and the panel is discharged. Thereafter, drying is performed in a state in which the flat side wall faces down. . Further, when drying the coating film in the panel, the air in the panel is forcibly sucked and exhausted.

[0007]

[Operation] A panel molded into a hollow double-walled structure is taken out of a molding die and cooled, and the paint is filled in the hollow interior. The paint is forcibly discharged by suction, so that a coating film is formed on the entire hollow inner wall surface of the panel. The panel having the coating film formed on the inner surface is dried with the side wall on the flat side facing downward, so that the coating film is maintained at an appropriate thickness and uniformly formed without the formation of a paint pool.
In this drying step, the air in the panel is forcibly sucked and exhausted, so that the panel is quickly dried.

[0008]

[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.

A method for manufacturing the shield panel 1 will be described below. (1) Forming Step As shown in FIG. 2, the shield panel 1 is formed by blow molding by sandwiching the plasticized and melted parison between the split molds 2 and 3 having cavities formed in the outer shape thereof. Is done. 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 Step As shown in FIG. 3A, the shield panel 1 is placed upright on the cylindrical portion 4 so as to be upright. Is injected to the vicinity of the cylindrical portion. At this time, a water-based paint 6 is used.

(3) Discharging Step As shown in FIG. 3B, the nozzle pipe 5 is suspended from the opening hole of the cylindrical part 4 to the vicinity of the lower end of the hollow part, and the paint 6 in the hollow part is sucked and discharged from the nozzle pipe 5. I do. At this time, an apparatus as shown in FIG. 4 is used as a means for injecting and sucking the paint 6. In the figure, 7 is a filling pump connected to the paint tank 8 and 9 is a suction pump, which are connected to the nozzle pipe 5 via a solenoid valve 10. By switching the solenoid valve 10, the filling and suction of the paint 6 is performed. Emissions are made. The paint in the discharge step may be discharged from the opening of the cylindrical portion 4 by inverting the shield panel 1 as shown in FIG.

(4) Drying Step At the other end of the shield panel 1 in the longitudinal direction, a small hole 11 is formed in a portion that does not interfere with the appearance of the panel, and FIG.
As shown in (c), the pipe member 12 connected to the air blowing or suction means is connected to the opening hole of the cylindrical portion 4 to inject or suck air into the shield panel 1 so that the air inside the hollow is reduced to the small hole. 11 and circulates with the outside air to forcibly dry the coating inside the hollow. Thereafter, the cylindrical portion 5 is cut off, and the opening of this portion is closed. The small hole 11 provided at the other end is left open for ventilation of the hollow interior. The injection air may be ordinary air, but dry air or high-temperature air is used.

In this drying step, as shown in FIG. 3 (c), the shield panel 1 is folded down to be horizontal and the above drying is performed. This is to make the coating on the inner wall surface uniform and appropriate. Note that functional members such as ribs, foolproofs, brackets, and projections for switches are integrally formed three-dimensionally on the back surface of the shield panel used as the housing of the electric device. Therefore, the rib 1
When there is a functional member having a three-dimensional shape such as 3, the side wall (back surface) on which the functional member is located is set to the upper side, and the flat side wall is positioned below. This is because, when the side wall with the functional member is located on the lower side, the thickness of the coating film changes due to the unevenness of the functional member. 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.

[0014]

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. Further, the paint 6 filled in the hollow interior of the shield panel 1 is forcibly filled through the nozzle pipe 5, and the excess paint 6 is sucked and forcibly discharged by the nozzle pipe 5, The coating process of the paint can be performed in a short cycle time. Further, by drying the shield panel 1 in the drying process in a state in which the flat side wall is turned down and lying down, a local paint pool is prevented, and a coating film having a uniform thickness can be obtained. In addition, a long drying time is not locally required, and the entire inner wall surface can be dried with a uniform drying time. Furthermore, in the above-mentioned drying process, since the inside of the hollow of the shield panel 1 is forcibly ventilated, it can be dried in a short time.

[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), (c), and (d) are explanatory views showing steps of filling, discharging, and drying of paint.

FIG. 4 is a circuit diagram showing an apparatus for filling and discharging paint.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electromagnetic wave shield panel, 2, 3 ... Split mold, 4 ... Tube part, 5 ... Nozzle tube, 6 ... Paint, 7 ... Filling pump, 8 ... Paint tank, 9 ... Suction pump, 10 ... Solenoid valve, 11
... small holes, 12 ... pipe members, 13 ... ribs.

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

Claims (3)

(57) [Claims] 1. A plastic panel having a hollow double-walled structure is molded, taken out of a molding die, and a paint having electromagnetic wave shielding properties is applied to an opening in the panel through an opening provided at one end of the panel. Inject near the hole, then insert a nozzle tube from the opening hole to the bottom of the hollow interior, suction and discharge the excess paint in the panel with this nozzle tube,
A method for manufacturing an electromagnetic wave shield panel, comprising drying a coating film adhered to an inner wall of a hollow portion of a panel. 2. A plastic panel having a hollow double-walled structure is molded and taken out of a molding die, and a paint having an electromagnetic wave shielding property is filled in the hollow interior of the panel.
In a method for manufacturing an electromagnetic wave shield panel in which the coating is applied and then the excess coating is discharged, and the coating adhered to the inner wall of the hollow portion is dried, the coating is filled and applied to the panel in an upright state. A method for producing an electromagnetic wave shielding panel, wherein the drying is carried out in a state of being laid down with the side wall on the flat side facing down. 3. The method according to claim 2, wherein air in the panel is forcibly sucked and exhausted when drying the coating film in the panel.
The manufacturing method of the electromagnetic wave shield panel of the description.