JP2001111285A - Highly incombustible gasket for shielding electromagnetic wave and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gasket for shielding electromagnetic waves which is highly incombustible and flexible, and its manufatcuring method. SOLUTION: This gasket uses a core material, made of a porous elastic body which is made by foaming a melamine resin, and the outer surface of the core material is covered with a conductive covering layer which is incombustible and flexible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gasket for electromagnetic wave shielding which has both high flame retardancy and electrical conductivity, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Electronic devices such as computers and word processors, and various other electronic devices having a microcomputer as a control element are liable to malfunction due to disturbances such as electromagnetic waves that enter the device from the outside. In addition, these electronic devices often generate electromagnetic waves to the outside of the device housing during operation and become a harmful noise source. This type of electromagnetic interference (EMI) or interference from lower frequency radio waves
In order to protect the electronic device and the like from (RFI) and prevent leakage to the outside, a shield is generally provided on the device housing.

[0003] This electromagnetic wave shielding is performed by, for example, applying a conductive paint to the inside of a housing that forms a housing of a computer, or covering a central processing unit (CPU) with a metal plate or a wire mesh. By the way, since the housing of the computer generally has a structure in which a plurality of parts are divided, a small gap generated when these covers are fitted, and a place where connector terminals for connecting various modules are installed are not improper. It is known that an electromagnetic wave enters or leaks from a gap generated by avoidance, which also causes a device to malfunction. For this reason, by sticking a soft conductive member, for example, in the form of a sheet, to a location along the parting line of the casing or an installation location of a connector terminal or the like, the electromagnetic waves can enter the casing or enter the outside. Techniques have been implemented to prevent leaks to the public. Since this conductive member fills a division gap or the like when a plurality of parts of the housing are united, it is generally called a gasket in view of its function.
Accordingly, this specification will be used hereinafter in the specification of the present application.

As this type of technology, a core material is formed by forming a foamed material having elasticity such as polyurethane foam into a column shape, and a gasket in which the core material is covered with a woven cloth of conductive fiber, a conductive material, or the like. There is known a gasket (US Pat. No. 4,857,668) in which a wet or dry metal plating is applied to a conductive cloth material and the periphery of the core material is covered with a conductive cloth material. In addition, instead of using conductive fibers or conductive cloth, an electromagnetic wave shielding gasket in which an elastomer core is surrounded by a conductive wire mesh is disclosed in
96396.

[0005] The above-mentioned gasket for electromagnetic wave shielding,
It is extremely effective that electromagnetic waves can be prevented from entering inside or leaking outside by being provided along the dividing line of the housing or provided in the mounting opening of the connector terminal or the like. However, the conductive fibers, conductive cloths and other conductive wire meshes that form part of these gaskets lack material flexibility and are considerably more rigid than the polyurethane foam used as the core material. Has become. For this reason, there is no problem if the dividing line in the housing (which has been subjected to conductive treatment such as application of a conductive paint or resin molding of a conductive powder) is straight, but the dividing line may have small irregularities depending on the location. If it is formed or curved with a relatively small curvature, the conductive fiber or wire mesh when arranging the gasket, because of its rigidity,
Following these changes in shape becomes difficult, wrinkles are generated and the gap cannot be completely filled, and there is a serious drawback that electromagnetic waves can enter from outside through this.

[0006]

In order to avoid such a problem, it has been proposed to use a flexible elastic material such as urethane for both the core material and the conductive coating layer covering the core material. You. However, since these elastic bodies are generally high-molecular organic substances and easily combustible, there is a problem in that they are ignited or melted when incorporated into an electronic device housing such as a computer or a word processor which generates a large amount of heat. In particular, regarding these electronic devices, since the United States specifies retention of high flame retardancy in the UL standard, it is absolutely necessary to meet the standard in order to export to the United States, and a higher standard is required. It is desirable to receive certification at the standard. Therefore, as a method of increasing the flame retardancy of the gasket, a method of putting a large amount of a flame retardant into the raw material of the elastic body is considered. In this case, however, the hardness of the elastic body is increased and the shape following property is poor. Is pointed out. That is, it has conventionally been very difficult to produce an elastic body for electromagnetic wave shielding having both flexibility and high flame retardancy.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the problems associated with the prior art, and has been proposed in order to solve the problem in a favorable manner. It is an object to provide a gasket and a method for manufacturing the gasket.

[0008]

In order to overcome the above-mentioned problems and achieve the intended object, a highly flame-retardant electromagnetic wave shielding gasket according to the present invention comprises a core made of a porous elastic material obtained by foaming a melamine resin. And a conductive coating layer having flame retardancy and flexibility covering the outer surface of the core material.

In order to overcome the above-mentioned problems and achieve the intended object, a method for manufacturing a highly flame-retardant electromagnetic wave shielding gasket according to the present invention according to the present invention provides a method of manufacturing a porous elastic core material by foaming melamine resin. To form a resin layer of a moisture-curable resin containing a flame retardant on the outer surface of the core material, to give a catalytic metal layer having catalytic activity to the required plating metal to this resin layer, Next, the metal for plating is deposited on the catalyst metal layer to form a metal plating layer.

In order to overcome the above-mentioned problems and achieve the intended object, a method of manufacturing a highly flame-retardant electromagnetic wave shielding gasket according to another aspect of the present invention is to form a porous elastic body by foaming melamine resin. After preparing a core material, forming a resin layer of a platable synthetic resin containing a flame retardant on the outer surface of the core material, after performing a predetermined roughening treatment on the outer surface of the resin layer,
A catalyst metal layer having catalytic activity is provided to a required plating metal, and then the plating metal is deposited on the catalyst metal layer to form a metal plating layer.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a highly flame-retardant gasket for electromagnetic wave shielding and a method of manufacturing the same according to the present invention will be described.
Preferred embodiments will be described below with reference to the accompanying drawings.

As shown in FIG. 1, a gasket for an electromagnetic wave shield according to a preferred embodiment of the present invention covers a core material 10 made of a porous elastic body of melamine resin and covers the whole or a required portion of the core material 10. It is basically composed of the conductive coating layer 12. The conductive coating layer 12 includes a resin layer 14 formed of a resin 20 and having a characteristic of adsorbing a catalyst metal 22 described later, a catalyst metal layer 16 adsorbed on the resin layer 14, and a catalyst metal layer 16. Catalyst metal 2 that forms
And a metal plating layer 18 formed with two fine particles as nuclei.

As the core material 10, a porous elastic body (hereinafter referred to as "melamine elastic body") formed by foaming a melamine resin having extremely high flame retardancy as a raw material is used. The melamine elastic body is produced by adding a foaming aid and a catalyst to a melamine resin aqueous solution or aqueous dispersion, and heating,
It is a continuously permeable noncombustible porous body having an extremely fine cell diameter (about 10 to 50 μm) and a high porosity (density of about 5 to 20 kg / m ³ ). The core material 10 is formed into a sheet shape or a string shape according to the structure inside the electronic device housing to be arranged. 20-thick if sheet-like
Approximately 1mm, width 20 to 2mm when it is a string
The degree is preferred.

The resin 20 forming the resin layer 14 is roughly classified into the following two. 1: Synthetic resin that can be plated by a conventional plastic plating method Examples of the resin 20 that can be used in the present invention include a synthetic resin that can be plated with plastic. Such resins include ABS (acrylonitrile butadiene styrene resin), PC (polycarbonate resin), PC / ABS
(Alloy of PC and ABS), PA (polyamide resin), PP
S (polyphenylene sulfide resin), PES (polyether sulfone resin), PEI (polyetherimide resin), PPO (modified polyphenylene oxide resin), P
OM (polyoxymethylene resin), PP (polypropylene resin), PBT (polybutylene terephthalate resin), and the like are used. A flame retardant obtained by mixing a predetermined amount of a flame retardant with them is used for use. Since a pretreatment method including a mechanical or chemical roughening step according to each material has been established for the resin layer 14 formed of the synthetic resin that can be plated, this treatment is performed in advance. This allows the application of the catalyst metal 22. 2: Moisture-curable resin A typical example is a moisture-curable modified silicone resin. This is a resin that has a certain degree of flame retardancy and is characterized by being cured by atmospheric moisture. In order to exhibit the same high flame retardancy as that of the melamine resin, it is preferably used by adding a flame retardant.
The thickness is about 0.05 to 0.5 mm, and it is possible to form a water-impermeable continuous layer that completely blocks invasion of various chemicals for electroless plating or electrolytic plating to the core material of the melamine elastic body. Desired. Since the moisture-curable modified silicone resin generally has a high viscosity, it can be applied by a roll coater or the like, and the concentration can be adjusted with a solvent such as xylene, so that a uniform and thin resin layer 14 can be easily formed. . In addition, since the curing is performed by the atmospheric humidity, the curing speed can be easily controlled by controlling the moisture applied to the core material 10. The modified silicone resin,
The catalyst metal 22 has a high physical adhesion ability to various substances, and a large number of functional groups remaining in the structure in an unreacted state after curing or newly generated by reaction with moisture. It is presumed that strong adhesion to the metal plating layer 18 is indirectly expressed by capturing and adsorbing a large number of.

As the flame retardant which exhibits flame retardancy when mixed with each of the above-mentioned resins 20, any known flame retardant may be used. However, from the viewpoint of environmental protection, a small amount of a halogen compound is not contained. Those exhibiting flame retardancy in an amount are suitably employed. The flame retardant mixed with the resin 20 is
It should be considered that the resin 20 does not bleed (bleed) on the surface and does not affect the electronic components.
As a material that satisfies these conditions, for example, a red phosphorus-based flame retardant can be used. It is desirable to use a hydrous metal compound or a nitrogen compound in combination as other flame retardants. In this case, smoke emission is suppressed and the effect of blocking oxygen is also improved, so that flame retardancy is further improved.

As the catalyst metal 22, a noble metal having catalytic activity in an electroless plating reaction such as palladium is preferably used, and in addition, gold, silver, ruthenium, rhodium, palladium, iridium, osmium or platinum can be used. . The method of forming the catalyst metal layer 16 by applying the catalyst metal 22 to the resin layer 14 differs depending on whether a synthetic resin that can be plated by a conventional plastic plating method or a moisture-curable resin is used. However, a specific method will be described later. The catalyst metal layer 16 does not need to be formed as a continuous layer, but may be adsorbed on the resin layer 14.

The plating metal 24 includes a first plating metal 24a for forming the first metal plating layer 18a and a second plating metal 24 for forming the second metal plating layer 18b.
b, and a metal having high reflectivity to the incident electromagnetic waves, that is, a metal having high conductivity and a metal having high corrosion resistance are employed. Generally, copper, nickel-phosphorus alloy, nickel-boron alloy, silver, gold, palladium, tin, solder or cobalt, etc. can be used,
In particular, gold, silver or copper is preferable as the first plating metal 24a, and nickel-phosphorus, nickel-boron, gold, palladium or chromium is preferable as the second plating metal 24b.

[0018]

[Manufacturing method] The manufacturing method of the highly flame-retardant electromagnetic wave shielding gasket according to the present invention is largely divided into a pretreatment step S1, a conductive step S2 and a finishing step S3, as shown in FIG. The pre-processing step S1 includes a core material manufacturing step S11 for manufacturing and processing a melamine elastic body serving as the core material 10 into a predetermined shape, and a resin indispensable for applying metal plating to the core material 10 which is an electrically non-conductive material. And a resin layer providing step S12 for forming the layer 14.

The conductive step S2, which is performed subsequent to the pretreatment step S1, includes a step of forming a catalyst layer containing desired catalytic metal fine particles exhibiting catalytic activity for electroless plating on the resin layer 14 formed on the core material 10. A catalyst adsorption step S21 of adsorbing the metal 22 to form the catalyst metal layer 16 and immersing the catalyst metal layer 16 in a first plating bath 30 that is appropriately selected to form a first metal layer 16 having a predetermined thickness on the catalyst metal layer 16. A first plating step S22 for providing a metal plating layer 18a, and immersion in a second plating bath 32 to form the first metal plating layer 18a.
a), a second plating step S23 of applying the second metal plating layer 18b on the substrate a. After the above steps, the processing and inspection in the inspection step S3 are performed to complete the application of the metal plating to the electric nonconductor. In some cases, the first plating step S22 and the second plating step S23
Subsequently, an electrolytic plating step S24 may be performed to further increase the thickness of the metal plating layer 18. The electrolytic plating step S24 is selectively performed as appropriate depending on various physical properties (eg, conductivity) required of the gasket.

In the core material manufacturing step S11, as described above, the melamine elastic material is manufactured from the melamine resin raw material, and the manufacturing method is as follows. : Pre-condensation product of melamine / formaldehyde, water, anionic surfactant as foaming agent, acid (catalyst), and foaming aid (low boiling point liquid that does not mix with water) are mixed in predetermined amounts and stirred at high speed. After that, it is rapidly foamed and cured by irradiating microwaves. After production, secondary curing is performed to remove free formalin and residual water. In combination with the melamine-formaldehyde precondensate,
Even when a copolymer using an amino resin material such as a urea / formaldehyde initial condensate or a guanamine compound and formaldehyde initial condensate is used, a foamed elastic body having high flame retardancy can be obtained.

Resin application step S12 and catalyst adsorption step S
21 is different from the resin applied in the resin applying step S12 (a resin that can be plated by a conventional plastic plating method or a moisture-curable resin), which causes a difference in the following manufacturing process.

1: When the resin layer 14 is formed from a synthetic resin that can be plated by a conventional plastic plating method. Resin application step S12:
0 is thinly coated. For this coating, a coating method in which the resin is dissolved and applied by means such as spraying or brushing, and a coating method in which the resin is melted by an extruder and extruded into a film or a tube, while being applied to the surface of the core material 10. A so-called extrusion coating method can be used. In the case of the coating method, the porous material of the core material 10 is noted, the viscosity is adjusted to be high, and the resin layer 14 is formed only near the surface. Catalyst adsorption step S21: First, washing is performed with an alkaline aqueous solution in order to remove oily dirt and the like at the time of molding the surface of the core material 10. This alkaline aqueous solution usually contains sodium phosphate or a nonionic surfactant which facilitates catalyst adsorption. Next, a chemical roughening method corresponding to the type of the resin is performed. For example, in the case of an ABS resin, it is immersed in a high-concentration solution of chromic anhydride and sulfuric acid at a high temperature to dissolve the butadiene rubber phase, thereby forming a fine uneven structure on the surface and roughening the surface. It is performed by adding a group. In the case of PC,
Prior to the etching with the chromic acid / sulfuric acid mixture,
A method in which the resin surface is swelled by immersion in an organic solvent and roughened by crack formation due to stress generation is suitably employed. For PA, it is common to add a filler and etch with concentrated hydrochloric acid. After the etching is completed, the complex salt colloid consisting of tin and palladium chloride is finally adsorbed on the roughened surface, and then dipped in an accelerator bath containing sulfuric acid to adsorb only the palladium metal nucleus on the surface. Thus, the catalyst metal layer 16 is formed.

2: In the case of forming the resin layer 14 from a moisture-curable resin Resin application step S12: mixing and kneading a red phosphorus-based flame retardant, a hydrated metal compound, a nitrogen-containing compound, etc. with the moisture-curable resin. I do. The compounding ratio in this case is 5 to 20 parts by weight of a red phosphorus-based flame retardant based on 100 parts by weight of the curable resin resin. May be added up to about 100 parts or about 25 parts, respectively. Since the composition produced in this manner has a high viscosity, it is preferable to use a roll coater or the like to apply the composition to the core material 10, and the composition is quickly cured by moisture in the air at room temperature or under heating. Catalyst adsorption step S21: A colloid of the catalyst metal 22 having a catalytic property for the electroless reaction is applied and adsorbed on the surface of the resin layer 14 by a method such as immersion, spray coating or brush coating. The colloid of the catalyst metal 22 is obtained by dissolving a water-soluble salt of the catalyst metal compound, adding a surfactant, and adding a reducing agent while stirring vigorously. Although there are various surfactants, anionic or cationic surfactants are preferable, and examples thereof include soap, higher alcohol sodium sulfate, sodium alkylbenzene sulfonate, sodium polyoxyethylene alkyl ether sulfate, and lauryl. Trimethylammonium chloride or alkylbenzyldimethylammonium chloride is used.

Plating step S22 in conductive step S2
Steps S23 and S23 are for applying a conductive first plating metal 24a and a corrosion-resistant second plating metal 24b to the catalyst metal layer 16 by electroless or electrolytic plating, respectively. In any case, the plating employed in the first plating step S22 and the second plating step S23 is preferably electroless plating which does not require power supply. The first metal plating layer 18a is made of electroless copper, and the second metal plating layer 18b is made of an electroless nickel-phosphorus alloy. At this time, the thickness of the first plating layer 18a and the thickness of the second plating layer 18b are each 0.1 mm.
It is preferably about 2 to 2 μm and about 0.1 to 1 μm. If the thickness is too large, the production time and the production cost increase, and if the thickness is too small, the desired function cannot be performed.

In the first plating step S22, ions of the first plating metal 24a stabilized by a chelating agent or the like and a reducing agent capable of reducing the ions coexist under conditions of appropriate pH and temperature. The core material 10 having the catalyst metal layer 16 adsorbed thereon is immersed in the first plating bath 30. The first metal plating layer 18a is formed in the previous stage S
It is formed by a precipitation reaction using the catalyst metal 22 adsorbed at 21 as a nucleus. In the subsequent second plating step S23, the ions of the second plating metal 24b are stabilized by a chelating agent or the like, and the second plating step S23 is applied using a second plating bath 32 having appropriate pH and temperature conditions. As described above, the first plating layer 18a formed of the first plating metal 24a mainly exhibits a shielding property of reflecting an incident electromagnetic wave with high conductivity, and the first plating layer 18a is formed from the second plating metal 24b. The second plating layer 18b, which is formed on the first plating layer 18a in a laminated manner, exhibits high corrosion resistance and protects the first plating layer 18a.

The metal plating layer 18 composed of the first metal plating layer 18a and the second metal plating layer 18b can improve the electromagnetic wave shielding ability in proportion to the thickness. However, since the gasket is required to have physical properties that cause large compressive deformation at low stress, the first metal plating layer 18a and the second metal plating layer 18b each have a minimum shielding (conductive) property and a minimum corrosion resistance that can ensure corrosion resistance. The thickness is more preferable.

The gasket 28 on which the conductive coating layer 12 having a desired electromagnetic wave shielding property is formed can be obtained from the core material 10 by the pretreatment step S1 and the conductive step S2 performed so far. In the finishing step S3 that is finally performed, the gasket 28 is subjected to molding and inspection such as washing and drying, cutting or punching into a predetermined shape, and the like.

Preferred experimental examples of the present invention are shown below, but the present invention is not limited to these examples.

[0029]

[First experimental example] Core material production stage A raw material having the following formulation was weighed in a cup in a prescribed amount and stirred for 45 seconds with a stirrer set at a rotation speed of 3000 rpm. After stirring, prepared inner dimensions 400 × 400 × 70mm
Was placed in a PP test piece mold, and the piece mold was clamped and irradiated with microwaves for 140 seconds by a microwave generator having an output of 1 kW. After the irradiation, the foam was removed from the piece mold, placed in a cure furnace set at 150 ° C. for 4 hours, and dried and cured to obtain a melamine elastic body. (Formulation) Trimethylolmelamine 100 parts by weight Water 35 Sodium dodecylbenzenesulfonate 20 Formic acid 2 Pentane 20

[0030] The cured foam is cut with a stub machine (cutting machine).
Cut the melamine elastic body skin layer to a thickness of 10m
m, and then cut to a width of 10 mm.
A string-shaped core material of 0 × 10 × 400 mm was used. The mechanical properties of this core material were as follows. Foam density [kg / m ³ ] 8 Tensile strength [Mpa] 0.018 Elongation [%] 20 Tear strength [N / cm] 0.45 50% Compression set [%] 26.8 Repeated compression set [%] 7.0 (Test method conforms to JIS K6401)

Resin application stage A red phosphorus-based flame retardant (product name: Nova Excel F5: manufactured by Rin Kagaku Kogyo Co., Ltd .: average particle size) per 100 parts by weight of a moisture-curable modified silicone resin (product name: Super X: manufactured by Cemedine Co., Ltd.) 6μ
m, phosphorus content 93%) were added and mixed in dry nitrogen with a biaxial kneader to obtain a heat-resistant moisture-curable resin. Next, the cores were arranged, and the resin was applied to each side by a bar coater to a thickness of about 0.1 mm and dried in air for 1 hour. This coating operation was performed a total of four times, and the entire periphery was covered with a resin layer formed of a flame-retardant resin.

Catalyst Adsorption Step 0.1 g of stearyltrimethylammonium chloride (product name Cotamine 86P Conc) was added to a pure aqueous solution consisting of 0.089 g / L of palladium chloride (PdCl ₂ ) and 0.146 g / L of sodium chloride (NaCl). / L was added to the main solution, and a solution obtained by previously dissolving 0.076 g of sodium borohydride (NaBH ₄ ) in a small amount of pure water was added. Produced. This palladium colloid catalyst solution was sufficiently applied by spray coating to the core material prepared in the pretreatment step, and then dried at a temperature of 100 ° C. for 30 minutes in a high-temperature oven capable of setting the temperature.

First plating stage After washing with water, an electroless copper plating bath (product name Omnishield 15)
98: Shipley Far East Co., Ltd .: standard formulation) was plated at a temperature of 30 ° C. for 30 minutes to obtain about 1 μm
Was formed. Second plating step Next, an activation bath containing palladium chloride (Omnishield 1501: Shipley Far East Co., Ltd .: standard blending)
Was treated for 1 minute at a temperature of 25 ° C. to obtain surface activity. After washing with water to sufficiently remove the activation bath solution, an electroless nickel plating bath (product name Omnishield 1580: manufactured by Shipley Far East Co., Ltd.) is used as a second plating step:
The standard mixture was plated at a temperature of 30 ° C. for 5 minutes to form a second metal plating layer of about 0.25 μm. Finishing Step Washing and drying were sufficiently performed to obtain a gasket.

(Result): The gasket thus obtained was cut into a length of 50 mm, and the resistance between the opposing sides was measured while compressing the gasket. When the compression ratio was 10% to 80%, the resistance was 0%. Good conductivity of .05Ω or less was obtained.
In addition, when a combustion test was conducted in accordance with UL94 flame retardancy evaluation criteria, no ignition occurred, or the flame was extinguished immediately after ignition, and the rating was rating V0. From these results, it is determined that the gasket obtained in the present experimental example has sufficient EMI shielding properties and flame retardancy.

[0035]

SECOND EXPERIMENTAL EXAMPLE A melamine elastic body was obtained through the same compounding and prescription and core production stage as in the first experimental example. The cured foam was sliced to a thickness of 3 mm by cutting the skin layer of the melamine elastic body with a scalpel (cutting machine),
A sheet-shaped core material of 00 × 400 × 3 mm was used. The mechanical properties of this core material were the same as in the first experimental example, and are not described.

Resin application stage A red phosphorus-based flame retardant (product name Nova Excel F5: manufactured by Rin Kagaku Kogyo Co., Ltd .: average particle size) per 100 parts by weight of moisture-curable modified silicone resin (product name Super X: manufactured by Cemedine Co., Ltd.) 6μ
m, phosphorus content: 93%) and 10 parts of aluminum hydroxide (product name: Hijilite H42M: manufactured by Showa Denko KK: average particle size: 1.)
(0 μm) and mixed with dry nitrogen in a twin-screw kneader to obtain a flame-retardant moisture-curable resin. Next, the cores were arranged, and the resin was applied to each side by a bar coater to a thickness of about 0.1 mm and dried in air for 1 hour.
This coating operation was performed on both sides of the sheet core material. Next, the same catalyst adsorption step as in the first experimental example 1 described above,
The first plating step, the second plating step, and the finishing step were sequentially performed to obtain a finished product.

(Results): Using the completed gasket thus obtained, the EMI shielding effect was measured for the electric and magnetic wave shielding effects according to the KEC method. The electric field wave 70 at a frequency between 100 MHz and 1000 MHz.
dB or more, and the magnetic field wave was 40 dB or more. Also, UL9
4 When a combustion test was performed according to the flame retardancy evaluation criteria,
The rating was 0.

[0038]

[Third Experimental Example] Core material production stage A string-shaped core material of 10 × 10 × 400 mm was obtained through the same blending formulation and core material production stage and processing as in the first experimental example described above. The mechanical properties of this core material were the same as in the first experimental example, and are not described.

Step of applying resin A crosshead having an opening having an outer peripheral dimension of 12 × 12 × 0.1 mm and a hollow part for passing a core material as an object to be coated is used. ABS resin
(Psycolak VW22: manufactured by Ube Sicon: Flame retardant UL
94-V0), the string-shaped core material was extruded or sent out from the hollow portion of the die, thereby forming a resin layer of ABS resin on the surface of the core material.

Catalyst adsorption step First, a treatment was performed so that the core material was not exposed on the end face, and the position was fixed by hanging on a rack. Next, the core material was prepared by adding sodium hydroxide (25 g / L) and sodium carbonate (25 g / L).
And the aqueous solution of sodium phosphate (25 g / L) and a cleaning solution containing a nonionic surfactant (1 g / L). Subsequently, an aqueous solution of chromic anhydride (42
(0 g / L) and 98% sulfuric acid (380 g), and the surface was roughened by immersion for 5 minutes at a temperature of 68 ° C. to collect and wash with water. Finally, the mixture was neutralized with 35% hydrochloric acid (100 ml / L) to sufficiently remove the chromic acid used as the etching solution, and thereafter, 30 ml of Catalyst C (manufactured by Okuno Pharmaceutical Co., Ltd .: tin palladium chloride complex) was used. / L and 35% 200 ml / L mixed in a catalytic metal solution at a temperature of 30 ° C. for 3 minutes to remove tin using a 98% sulfuric acid (100 ml / L) solution at 40 ° C. Further, by performing washing with water, fine palladium metal particles as a catalyst metal were adhered to the resin layer. A first plating step similar to the first experimental example described above,
The gasket was obtained by sequentially performing the second plating step and the finishing step.

(Results): The gasket thus obtained was cut into a length of 50 mm, and the resistance between the opposing sides was measured while compressing the gasket. Good conductivity of .05Ω or less was obtained.
In addition, when a combustion test was conducted in accordance with UL94 flame retardancy evaluation criteria, no ignition occurred, or the flame was extinguished immediately after ignition, and the rating was rating V0. From these results, it is determined that the completed gasket obtained in this example has both sufficient EMI shielding properties and flame retardancy.

[0042]

As described above, according to the present invention, a metal plating layer imparting conductivity is provided on the surface of a foamed elastic body made of melamine resin having high flame retardancy as a core material. In addition, the elastic body and the plating layer can be in a firmly bonded state by the interposition of the resin layer, so that the flame retardancy is much higher than before, and the elasticity and electromagnetic wave shielding property sufficient for use in the housing of electronic equipment And a gasket having the following is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view of a highly flame-retardant electromagnetic wave shielding gasket according to an embodiment of the present invention, partially cut away.

FIG. 2 is a flowchart illustrating a method of manufacturing a highly flame-retardant gasket for electromagnetic wave shielding according to the present invention.

[Explanation of symbols]

 Reference Signs List 10 core material 12 conductive coating layer 14 resin layer 16 catalyst metal layer 18 metal plating layer 18a first metal plating layer 18b second metal plating layer 20 resin 24 metal for plating

Claims (10)

[Claims] 1. A core material (10) made of a porous elastic material in which a melamine resin is foamed, and a flame-retardant and flexible conductive coating layer (12) for covering the outer surface of the core material (10). ) A highly flame-retardant electromagnetic wave shielding gasket characterized by comprising: The conductive coating layer (12) comprises a catalytic metal layer (16) having catalytic activity on a predetermined plating metal (24).
And a metal plating layer provided on the surface of the catalyst metal layer (16).
2. The highly flame-retardant electromagnetic wave shielding gasket according to claim 1, wherein the gasket comprises a resin layer containing a flame retardant and is adhered to the core material. 3. The resin layer (14) is formed of a moisture-curable resin such as a moisture-curable modified silicone resin.
The highly flame-retardant electromagnetic wave shielding gasket described. 4. The highly flame-retardant electromagnetic wave shielding gasket according to claim 2, wherein the resin (14) is formed of a synthetic resin that can be plated, such as an ABS resin. 5. The core material (10), wherein the metal plating layer (18) is
A highly flame-retardant product according to any one of claims 1 to 4, which is a laminate of a first metal plating layer (18a) formed on the side of the first metal plating layer and a second metal plating layer (18b) formed on the front surface side. Gasket for electromagnetic wave shielding. 6. A core material (10) of a porous elastic body produced by foaming a melamine resin, and a resin layer (14) of a moisture-curable resin containing a flame retardant on an outer surface of the core material (10). The resin layer (14) is provided with a catalytic metal layer (16) having a catalytic activity for a required plating metal (24), and then the plating metal (16) is provided on the catalytic metal layer (16). 24) A method for producing a highly flame-retardant electromagnetic wave shielding gasket, wherein 24) is deposited to form a metal plating layer (18). 7. The method according to claim 6, wherein the moisture-curable resin is, for example, a moisture-curable modified silicone resin. 8. A core material (10) of a porous elastic body is produced by foaming a melamine resin, and a resin layer (14) of a plateable synthetic resin containing a flame retardant is formed on an outer surface of the core material (10). After performing a roughening treatment on the outer surface of the resin layer (14), a catalytic metal layer (16) having catalytic activity on a required plating metal (24) is applied. A method for manufacturing a highly flame-retardant electromagnetic wave shielding gasket, wherein a metal plating layer (18) is formed by depositing the plating metal (24) on a catalyst metal layer (16). 9. The synthetic resin capable of being plated is, for example, A
The method for producing a highly flame-retardant electromagnetic wave shielding gasket according to claim 8, which is a BS resin. 10. The method for manufacturing a highly flame-retardant electromagnetic wave shielding gasket according to claim 6, wherein the plating metal (24) forms a metal plating layer (18) by electroless plating. .