JPH11168293A - Electromagnetic wave shielding gasket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic wave shielding gasket, with which molding process failure rate can be reduced without changing shape of molding, and electromagnetic wave can be stably shielded for a long period of time. SOLUTION: An electromagnetic-wave shielding gasket 10 is formed in band- like shape, wherein a clip part 12 having almost U-shaped cross-section where a cushion part 13 is placed on one external surface is integrally assembled with the cushion part 13. In this case, as the clip part 12 is formed by extrusion- molding chlorinated polyvinylchloride into band-like shape, the thermal deformation temperature of the clip part 12 can be improved when compared with the conventional general extrusion-molded product of polyvinylchloride. As a result, the release due to heating of internal residual stress generated by sizing treatment in the extrusion molding of the clip part 12 can be suppressed to the minimum, and the generation of crease and the exfoliation of a conductive coated part 14 can be inhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an electromagnetic wave shielding gasket, and more particularly, to a metal case for electromagnetic wave shielding or a lid for opening and closing an electromagnetic anechoic chamber which houses electronic and electrical equipment, an integrated circuit board, and the like. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic wave shielding gasket which can be easily mounted around the electromagnetic wave shielding gasket so as to be able to stably prevent leakage or intrusion of electromagnetic waves from a gap of the opening / closing lid for a long period of time without detaching due to thermal deformation.

[0002]

2. Description of the Related Art A conventional electromagnetic wave shielding gasket, which is mounted around a metal casing for shielding electromagnetic waves or a cover for an electromagnetic wave anechoic chamber which houses electronic and electric equipment, an integrated circuit board, and the like, is usually shown in FIGS. It was configured as shown.
That is, an opening is provided on one side surface of the metal casing 1 for shielding electromagnetic waves, and after inspection and repair of an electronic / electric device, an integrated circuit board, and the like housed using the opening, the opening is formed. The pair of left and right lids 2 and 3 that are rotatably attached are closed to shield the metal housing 1 from electromagnetic waves.

[0003] The gap between the periphery of each of the open / close lids 2 and 3 and the frame of the metal casing 1, and the open / close lids 2 and 3.
3, a relatively narrow band-shaped electromagnetic wave shielding gasket 4 is mounted, for example, the electromagnetic wave shielding gasket 4 mounted on the joint of the open / close lids 2, 3 is a line AA in FIG. It was mounted as shown in FIG. 4 cut along the line.

First, the electromagnetic wave shielding gasket 4
Is a clip portion 5 which is an extrusion molded product of a general polyvinyl chloride resin having a thickness of about 1 to 2 mm;
A cushion portion 7 of a sponge material, which is made of a synthetic rubber such as flame-retardant chloroprene rubber, urethane rubber, silicone rubber, ethylene propylene rubber, or an elastomer, having a substantially cross-sectional shape on one outer surface thereof, is previously formed. The outer surface of the cushion portion 7 together with a part of the other outer surface and the inner surface of the clip portion 5 is adhered to a double-sided tape adhered to the clip portion 5 by, for example, a copper and / or nickel Is applied to the surface of a conductive coating portion 8 formed by plating with a hot-melt type adhesive previously applied to integrate the clip portion 5 and the cushion portion 7.

[0005] In the conventional electromagnetic wave shielding gasket 4 described above, the side edge of the opening / closing lid 2 located on the lower side is entirely passed through a narrow gap 15 of the clip portion 5 (see FIGS. 1 and 2). When inserted along the inner surface formed into a substantially U-shape, a spring provided by the narrowing of the gap 9 and a plurality of lips projecting in a longitudinal direction from a part of the U-shaped inner surface are provided. When the side edge of the opening / closing lid 2 is gripped by the clip portion 5 due to the abutting action of the portion 5, and the upper opening / closing lid 3 is closed, the side edge of the opening / closing lid 3 is closed. The back surface presses the bump-shaped cushion portion 7 via the conductive covering portion 8 and compresses and deforms as shown by a broken line to seal the gap between the side edge of the opening / closing lid 3 and the back surface. Was.

The conductive coating 8 is in close contact with the frame of the metal casing 1 and the open / close lids 2 and 3 so that a conductive state is ensured. In order to form an effective electromagnetic wave shielding closed circuit, the position where the conductive covering portion 8 is attached to the clip portion 5 at both ends is considered.

[0007]

However, in the above-mentioned conventional electromagnetic wave shielding gasket 4, the clip portion 5, which is a general extruded product of a polyvinyl chloride resin having a thickness of about 1 to 2 mm, is formed at the time of molding. When the internal residual stress generated due to the sizing of the clip 5 is released by annealing (usually at a processing temperature of 90 ° C. for 50 minutes), the relatively small shrinkage (about 1.0%) of the clip portion 5 causes the narrow gap. 15, an opening deformation, so-called opening, occurs, and the gripping force on each side edge of the opening / closing lid body or the frame portion of the metal casing 1 shown in FIGS. As a result, a problem of falling off from the vicinity of the opening of the metal housing 1 was likely to occur.

[0008] Even the clip portion 5 in which the narrow gap 15 has not been expanded and deformed by the annealing process described above, is constituted by the subsequent integration of the cushion portion 7 and the conductive coating portion 8. As one member of the electromagnetic wave shielding gasket 4, it is mounted at a predetermined position around the opening of the metal housing 1, and when heating and cooling are repeated under a normal operating temperature condition of −30 ° C. to 80 ° C., the clip The release of the internal residual stress of the portion 5 is further promoted, and the cushion portion 7 and the conductive coating portion 8 are deformed by shrinkage. As a result, the conductive coating portion 8 is wrinkled and peeled, and the metal casing is formed. There is a drawback that the adhesion between the body 1 and the periphery of the opening is reduced and the electromagnetic wave shielding effect is also reduced.

The present invention solves the above-mentioned problems of the prior art, and provides an electromagnetic wave shielding gasket capable of stably shielding electromagnetic waves for a long period of time by reducing the molding defect rate without changing the shape. The purpose is to do so.

[0010]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
The cross section where the cushion portion is placed on one outer surface is substantially U
A band-shaped electromagnetic wave shielding gasket in which a U-shaped clip portion is integrally assembled with the cushion portion by a conductive coating portion, wherein the clip portion is formed by extruding chlorinated polyvinyl chloride into a band shape. Achieved by shielding gaskets.

Further, the object of the present invention is achieved by an electromagnetic wave shielding gasket, wherein the clip portion has a chlorine content of 62 wt% to 67 wt%.

[0012]

According to the electromagnetic wave shielding gasket of the present invention, a clip portion having a substantially U-shaped cross section in which a cushion portion is placed on one outer surface is integrally formed with the cushion portion by a conductive coating portion. In the electromagnetic wave shielding gasket of the above, since the clip portion is formed by extruding chlorinated polyvinyl chloride in a belt shape, the heat resistance of the clip portion is improved compared to a conventional general polyvinyl chloride extruded product. As a result, the release by heating of the internal residual stress generated by the sizing process or the like in the extrusion of the clip portion is minimized, and the heat shrinkage and deformation thereof, and the occurrence of wrinkles and peeling of the conductive coating portion are prevented. .

Further, in the electromagnetic wave shielding gasket of the present invention, since the clip portion has a chlorine content of 62 wt% to 67 wt%, the heat deformation temperature of the clip portion is about 90 ° C. to 100 ° C.
And other desired physical properties, such as a shrinkage factor and a thermal expansion coefficient, are imparted without impairing the extrudability.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the electromagnetic wave shielding gasket of the present invention will be described below in detail with reference to the accompanying drawings. 1 and 2 are cross-sectional views of the electromagnetic wave shielding gasket 10 of the present invention, taken along the line AA in FIG. As shown in FIG. 3, an electromagnetic wave shielding metal housing 1 containing electronic and electric equipment, an integrated circuit board, and the like has an opening on one side thereof and is rotatably attached to the opening. The pair of left and right lids 2 and 3 are closed to shield the metal casing 1 from electromagnetic waves.

The gap between the periphery of each of the open / close lids 2 and 3 and the frame of the metal casing 1 and the gap between each of the open / close lids 2 and 3 are relatively narrow according to the present invention. A band-shaped electromagnetic wave shielding gasket 10 having a width is mounted. For example, the electromagnetic wave shielding gasket 10 mounted on a joint portion of the respective opening and closing lids 2 and 3 is cut along the line AA in FIG. 1 and FIG. It is configured as shown in FIG.

First, the electromagnetic wave shielding gasket 10
A clip portion 11 which is a strip-shaped extruded product of chlorinated polyvinyl chloride having a thickness of about 1 to 2 mm, and a cross-sectional shape on one outer surface of the clip portion 11 having a substantially cross-sectional shape or L
A sponge cushion 13 or 13a made of synthetic rubber such as flammable chloroprene rubber, urethane rubber, silicone rubber, ethylene propylene rubber or the like or a sponge material, for example, is applied to the double-sided tape previously attached to the clip 11. Affixed to the cushion portion 13 together with a part of each of the other outer surface and the inner surface of the clip portion 11.
Alternatively, the outer peripheral surface of 13a is affixed with a hot-melt type adhesive previously applied to the surface of a conductive coating portion 14 formed by plating a polyester fiber cloth with copper and / or nickel, and the clip portion 11 and The cushion section
It is integrated with 13 or 13a.

In the above-described electromagnetic wave shielding gasket 10 of the present invention, the entire side edge of the opening / closing lid 2 located below is formed into a substantially U-shape through a narrow gap 15 of the clip portion 11. When inserted along the inner surface, the spring 15 provided by the narrowing of the gap 15 and the abutting action of a plurality of lip portions 12 projecting in a longitudinal direction on a part of the U-shaped inner surface. When the side edge of the opening / closing lid 2 is firmly gripped by the clip portion 11 and the upper opening / closing lid 3 is closed, the back surface of the side edge of the opening / closing lid 3 is covered with the conductive coating. The bump-shaped cushion portion 13 or 13a is pressed through the portion 14 and is compressed and deformed to seal the gap between the side edge of the opening / closing lid 3 and the back surface.

The conductive covering portion 14 is in close contact with the frame portion of the metal casing 1 and the open / close lids 2 and 3 to maintain a good continuity state, and the conductive covering portion 8 Both ends of the conductive covering portion 14 are connected to each other so that an effective electromagnetic wave shielding closed circuit is formed around the opening of the metal casing 1 and around the joining portion of the lids 2 and 3. Is set for the clip portion 11 to be attached.

Furthermore, the electromagnetic wave shielding gasket of the present invention
10 is the most different from the conventional electromagnetic wave shielding gasket 4 in that the clip portion 11, which is an extruded product of chlorinated polyvinyl chloride having a thickness of about 1 to 2 mm, suspends polyvinyl chloride in water, hydrochloric acid, or the like. Chlorinated in the presence of a catalyst, and the chlorine content is adjusted within the range of 63% to 66.5%. The chlorinated polyvinyl chloride whose chlorine content is adjusted to be in the range of 62 wt% to 67 wt% is once extruded from a die of an extrusion molding device into a flat plate having a thickness of about 1 to 2 mm, and subjected to sizing processing while cooling with water. The clip portion 11 having a substantially U-shaped cross section has a heat deformation temperature of about 20 ° C. to 30 ° C. higher than that of the conventional general polyvinyl chloride clip portion 5 due to the chlorine content. As a result, the release of the internal residual stress due to the annealing treatment (usually at 90 ° C. for 50 minutes) and subsequent heating in a practical environment is minimized, and the heat shrinkage and Deformation and wrinkling and peeling of the conductive coating 14 are prevented.

In particular, when the chlorine content of the chlorinated polyvinyl chloride constituting the clip portion 11 is adjusted to a range of 63 wt% to 66.5 wt%, the heat deformation temperature of the clip portion 11 becomes about 90 ° C.
~ 100 ° C and other desired physical properties without impairing extrudability, for example shrinkage of 0.05% to 0.1%, 4.4 x 10 ^-5
A coefficient of thermal expansion of / ° C is also given. As a result, expansion deformation of the narrow gap 15, that is, generation of a so-called opening, is suppressed, and a trouble that the electromagnetic wave shielding gasket 10 falls off around the opening of the metal housing 1 can be prevented, and It has an appropriate hardness for the extrudability, thereby reducing the defective rate.

Furthermore, the clip portion 11 in which the expansion deformation of the narrow gap 15 did not occur due to the annealing process,
As a member of the electromagnetic wave shielding gasket 10 formed by integrating the cushion portion 13 or 13a and the conductive coating portion 14 thereafter, the member is mounted at a predetermined position around the opening of the metal housing 1, Normal -30 ° C ~ 80
Even if heating and cooling are repeated under the use temperature condition of ° C., the release of the internal residual stress is suppressed to a minimum due to the improvement of the heat resistance of the clip portion 1, and the cushion portion 13 or 13a and the Wrinkling and peeling of the conductive coating portion 14 which does not cause deformation due to shrinkage together with the conductive coating portion 14 and therefore reduces the adhesion to the periphery of the opening of the metal housing 1 and reduces the electromagnetic wave shielding effect. Does not occur.

[0022]

The above described electromagnetic wave shielding gasket 10 of the present invention has the following novel effects. That is, the electromagnetic wave shielding gasket of the present invention is:
The cross section where the cushion portion is placed on one outer surface is substantially U
In a band-shaped electromagnetic wave shielding gasket in which a U-shaped clip portion is integrally assembled with the cushion portion by a conductive coating portion, the clip portion is formed by extruding chlorinated polyvinyl chloride into a band shape. The heat resistance of the clip is improved over that of a conventional general polyvinyl chloride extruded product. As a result, the release of the internal residual stress caused by the sizing process in the extrusion of the clip portion by heating is minimized, and the heat It has become possible to prevent shrinkage and deformation, as well as wrinkling and peeling of the conductive coating.

Further, in the electromagnetic wave shielding gasket of the present invention, since the clip portion has a chlorine content of 62 wt% to 67 wt%, the heat deformation temperature of the clip portion is about 90 ° C. to 100 ° C.
It is also possible to have other desired physical properties, such as shrinkage, thermal expansion coefficient, etc., without impairing the extrudability, thereby preventing the opening or shrinkage in the longitudinal direction during use. It became possible.

The cushion portion is not limited to the shape of a cross section in the shape of an L-shape or an L-shape. There is no problem as long as the cushioning property and the sealing property are maintained well.
Further, the conductive coating portion is not limited to a nonwoven fabric or a woven fabric made of the polyester fiber, which is plated with the copper and / or nickel, and other cloth having heat resistance, durability and flexibility. The material may be plated with another metal material having conductivity. The novel effects of the electromagnetic wave shielding gasket of the present invention described above are further clarified by Examples and Comparative Examples.

[0025]

Example -1: First, polyvinyl chloride was suspended in water in the presence of a chlorinated solvent, and then irradiated with ultraviolet rays to initiate a reaction to generate chlorine radicals. Chlorination, the chlorine content of 63wt% -66.5wt%
The chlorinated polyvinyl chloride pellets adjusted to have a thickness of 1 to 2 are temporarily prepared from the die of the extrusion molding apparatus.
It was extruded into a flat plate of about mm and sizing processing was performed while cooling with water to form a band-shaped clip portion having a substantially U-shaped cross section. Thereafter, an annealing treatment was performed under a processing condition of 90 ° C. × 50 minutes, and measurement and visual judgment were performed on the thermal deformation temperature, shrinkage rate, thermal expansion coefficient, and expansion deformation. -2: Next, a sponge material made of flame-retardant chloroprene was formed as a cushion portion into a substantially crooked cross-sectional shape. -3: Further, as a conductive coating portion, a woven fabric made of polyester fiber is plated with copper, and a clip portion and a cushion portion are used as shown in FIG. 1 by using a hot melt type adhesive made of polyester. After bonding and integrating the conductive coating portion to create three types of electromagnetic wave shielding gaskets based on the present invention, the temperature is 80 ° C. within a practical temperature range.
15.5hrs → 20 ℃ × 0.5hrs → -30 ℃ × 7.5hrs → 20 ℃ × 0.5h
rs → 50 ℃ × 15.5hrs → 20 ℃ × 0.5hrs → -30 ℃ × 7.5hrs →
Heating and cooling were performed according to the heat cycle conditions of 20 ° C. × 0.5 hrs × 3 cycles, and the workability of attachment to the periphery of the opening of the steel housing and the vicinity of the joint of the respective opening / closing lids and the presence or absence of falling off were observed. Table 1 shows the measurement and observation results of the examples.

[0026]

Comparative Example -1: First, a polyvinyl chloride pellet having a chlorine content of 56.8 wt% and a polyvinyl chloride suspended in water in the presence of a chlorinated solvent to start the reaction. Is irradiated with ultraviolet rays to generate chlorine radicals, chlorinating polyvinyl chloride and reducing its chlorine content from 59 wt% to 61 wt%.
The pellets of chlorinated polyvinyl chloride adjusted to the range of wt% and 67.5wt% were used as raw materials, respectively, and extruded from the die of the extrusion molding machine into a flat plate with a thickness of about 1-2mm, and then sizing treatment while cooling with water. Then, a band-shaped clip portion having a substantially U-shaped cross section was formed. After that, 90 ℃
An annealing treatment was performed under a treatment condition of × 50 minutes, and a measurement and a visual judgment were performed on the thermal deformation temperature, shrinkage rate, thermal expansion coefficient, and expansion deformation. -2: Next, a sponge material made of flame-retardant chloroprene was formed as a cushion portion into a substantially crooked cross-sectional shape. -3: Further, as a conductive coating portion, a woven fabric made of polyester fiber is plated with copper, and a clip portion and a cushion portion are used as shown in FIG. 1 using a hot-melt type adhesive made of polyester. After bonding and integrating the conductive coating portion to create four types of electromagnetic wave shielding gaskets according to the present invention, the temperature is 80 ° C. within a practical temperature range.
15.5hrs → 20 ℃ × 0.5hrs → -30 ℃ × 7.5hrs → 20 ℃ × 0.5h
rs → 50 ℃ × 15.5hrs → 20 ℃ × 0.5hrs → -30 ℃ × 7.5hrs →
Heating and cooling were performed according to the heat cycle conditions of 20 ° C. × 0.5 hrs × 3 cycles, and the workability of attachment to the periphery of the opening of the steel housing and the vicinity of the joint of the respective opening / closing lids and the presence / absence of detachment were observed. Table 1 shows the measurement and observation results of the comparative example.

[0027]

[Table 1]

As is clear from Table 1, the electromagnetic wave shielding gaskets (samples Nos. 1 to 3) of the present invention have a higher heat distortion temperature and shrinkage ratio than the electromagnetic wave shielding gaskets (samples Nos. 4 to 7) of the comparative example. In all respects, the thermal expansion coefficient, the expansion deformation of the clip portion, the mounting workability, and the presence / absence of falling off, it was confirmed that they were significantly superior from the viewpoint of electromagnetic wave shielding.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of the electromagnetic wave shielding gasket of the present invention, taken along line AA of FIG.

FIG. 2 is a cross-sectional view of another electromagnetic shielding gasket of the present invention, taken along line AA of FIG.

FIG. 3 is a perspective view of a metal case for shielding electromagnetic waves, which houses an electronic / electric device, an integrated circuit board, and the like.

FIG. 4 is a cross-sectional view of the conventional electromagnetic wave shielding gasket cut along the line AA in FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal housing 2 Opening / closing lid 3 Opening / closing lid 4 Conventional electromagnetic wave shielding gasket 5 Clip part 6 Lip part 7 Cushion part 8 Conductive covering part 10 Electromagnetic wave shielding gasket of the present invention 11 Clip part 12 Lip part 13 Cushion part 13a Cushion part 14 Conductive coating part 15 Gap

Claims (2)

[Claims] A cushion portion (13, 13) is provided on one outer surface.
a) a clip portion (11) having a substantially U-shaped cross section on which the cushion portion (13, 13) is placed by a conductive coating portion (14).
A band-shaped electromagnetic wave shielding gasket (10) assembled integrally with (a), wherein the clip portion (11) is formed by extruding chlorinated polyvinyl chloride into a band shape. 2. The clip part (11) has a chlorine content of 62.
The electromagnetic wave shielding gasket according to claim 1, wherein the content is from wt% to 67wt%.