JPH0349937B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a composite resin composition, and more particularly to a composite resin composition that has extremely high electromagnetic shielding performance, has no variation in shielding performance regardless of the shape of the processed product, and has excellent molding fluidity, molded appearance, etc. Conventionally, as materials for shielding electromagnetic waves, metals, metal-containing resins, laminates of wood and metal, and materials coated or plated with metal powder-containing paints have been known. However, although metal has good shielding performance, it is complicated to shape and requires secondary treatments such as burr treatment and polishing. Shielding performance is low in metal-containing resins or laminates of metal and resin. The shielding performance varies depending on the part of the processed product, making the shielding performance unstable. The molding processability, especially the molding fluidity, is poor, making it difficult to mold large molded products. The appearance of the molded product is poor. There are problems such as the need for secondary processing of the surface. Additionally, paints coated or plated with metal powder-containing paints have poor adhesion to the base material, and in particular, the adhesion deteriorates significantly over time, making it difficult to coat or plate objects with complex shapes. It has drawbacks such as: Thus, until now, no material has been proposed that is fully satisfactory as a material for shielding electromagnetic waves. Therefore, the present inventors conducted research to develop a material with good shielding performance, moldability, etc., and found that a composition containing a specific metal in a synthetic resin is excellent as a shielding material. The present invention was completed based on this. That is, the present invention comprises (A) a synthetic resin (hereinafter referred to as (A) component) of 4 to 30% by weight, (B) a metal having a low melting point and/or which can be plasticized by shearing (hereinafter referred to as (B) component). ) 90-10% by weight, (C) fibrous metal (hereinafter referred to as
It is called component (C). ) 3 to 30% by weight and (D) powdered metal (hereinafter referred to as component (D)) 3 to 30% by weight, wherein the (A) synthetic resin is an acrylonitrile-butadiene-styrene resin, Polypropylene, polyethylene, polystyrene, polyvinyl chloride, polyamide, polymethyl methacrylate, polycarbonate, polyoxymethylene, polyethylene terephthalate, polybutylene terephthalate, unsaturated polyester resin or epoxy resin, and (B) has a low melting point and/or shear. The plasticizable metal is one or more of lead, tin, and solder, and the fibrous metal (C) is one or more of brass fiber, nickel fiber, and aluminum fiber, and ( D) A composite resin composition characterized in that the powdered metal is one or more of brass powder, nickel powder, zinc powder, and iron powder. Specifically, the synthetic resin that is component (A) of the present invention includes acrylonitrile-butadiene-styrene resin (ABS resin), polypropylene, polyethylene,
Examples include polystyrene, polyvinyl chloride, polyamides such as nylon-6 and nylon-6,6, polymethyl methacrylate, polycarbonate, polyoxymethylene, polyethylene terephthalate, polybutylene terephthalate, unsaturated polyester resins, and epoxy resins. Next, the component (B) of the present invention, which is a metal that has a low melting point and/or can be plasticized by shearing, has a melting point that is lower than the decomposition temperature of the synthetic resin, and a metal that can be plasticized by shearing, such as normal molding. It is a metal that has one or both of the properties of becoming plastic and deformable at a temperature below its melting point by shearing by a processing machine or a kneading machine. Here, the low melting point metal is particularly preferably one with a melting point of 500°C or lower. Component (B) may be a single metal, an alloy, or a combination of these as long as it satisfies the above conditions. (B) Specifically, the ingredients are lead, tin, and solder.
One species or two or more species may be used. Component (C) of the present invention is a fibrous metal, and one or more of brass fibers, nickel fibers, and aluminum fibers are used. There are no particular restrictions on the shape, but the length is usually 1 to 5 mm,
Preferably 2-3 mm, diameter 5-80μ, preferably 10
~60μ is used. Next, component (D) of the present invention is a powdered metal,
One or more of brass powder, nickel powder, zinc powder, and iron powder is used. There are no particular restrictions on the size of the powder, but the particle size is usually 1 to 10 microns, preferably 2 to 8 microns. If the particle size exceeds 10 μm, the mechanical properties will deteriorate, and if the particle size is less than 1 μm, dispersion will be poor, which is not preferable. In the present invention, the blending amount of each component varies depending on the type of resin or metal used and the desired physical properties, but usually component (A) is 4 to 30% by weight and component (B) is 90 to 10% by weight. , (C) component 3 to 30% by weight, (D) component 3 to 30% by weight, preferably (A) component 5 to 23% by weight, (B) component 87 to 15% by weight, (C) component 3 to 30% by weight. ) component is 5 to 25% by weight, and component (D) is 5 to 25% by weight. The composite resin composition of the present invention can be obtained by kneading the above components. The components are kneaded by a conventional method, for example, using a kneading machine such as a Banbury mixer, a single-screw extruder, or a twin-screw extruder. For example, when using a Banbury mixer, the kneading is performed at a temperature of 100 to 150°C for 15 to 30 minutes, and when using an extruder, the kneading is performed at a temperature of 200 to 150°C.
Preferably, it is carried out at 250°C. The composite resin composition thus obtained has extremely high electromagnetic shielding performance. Furthermore, even when it is made into a molded product, the variation in shielding performance depending on the part is very small and stable. Furthermore, it has excellent molding fluidity and a good molded appearance, and can be manufactured from small to large molded products with high productivity without the need for secondary processing. Therefore, the composite resin composition of the present invention is particularly suitable as a shielding material, and can be widely used as a material for computer equipment, video/audio products, office equipment, electronic equipment, home appliances, automobile parts, communication equipment, etc. It can be used. Next, the present invention will be explained in detail with reference to Examples. Examples 1 to 29 and Comparative Examples 1 to 12 The ingredients shown in Table 1 were blended in predetermined amounts, and the mixture was kneaded and extruded using a Banbury mixer at the temperature shown in Table 1. 150mm x 150mm x 3mm plate, test piece compliant with ASTM D-256, at the temperature shown in Table 1.
A box-shaped molded product measuring 60 mm x 85 mm x 120 mm was molded. The obtained molded product was evaluated. The results are shown in Table 2. The evaluation method was as follows. Evaluation method 1 Volume resistivity The center point of the 60 mm x 120 mm surface (with a gate) of the 60 mm x 85 mm x 120 mm box-shaped molded product obtained by injection molding is A, and the center point of the 85 mm x 120 mm surface is B. The volume resistivity at each point was measured using a solid-state resistance bridge SW-1-TR, with the center point of the 60 mm x 85 mm surface being C. 2 Izod impact test Compliant with ASTM D-256 3 Formability Spiral flow length (SFL) Compliant with JIS K-7210

[Table] Appearance The appearance of the molded product used for volume resistivity measurement was visually judged. 〇…Aesthetics △…Slightly fibrous and fluffy ×…Strong fibrous fluff

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Claims (1)

[Scope of Claims] 1 (A) 4 to 30% by weight of synthetic resin, (B) low melting point and/or
Alternatively, a composition comprising 90 to 10% by weight of a metal that can be plasticized by shearing, (C) 3 to 30% by weight of a fibrous metal, and (D) 3 to 30% by weight of a powdered metal, which comprises (A) The synthetic resin is acrylonitrile-butadiene-styrene resin, polypropylene, polyethylene, polystyrene, polyvinyl chloride, polyamide, polymethyl methacrylate, polycarbonate, polyoxymethylene, polyethylene terephthalate, polybutylene terephthalate, unsaturated polyester resin or epoxy resin, (B) The metal that has a low melting point and/or can be plasticized by shearing is one or more of lead, tin, and solder, and (C) the fibrous metal is one of brass fiber, nickel fiber, and aluminum fiber. A composite resin composition characterized in that the powdered metal (D) is one or more of brass powder, nickel powder, zinc powder, and iron powder.