Electromagnetic wave-shielding materials

Claim 1

An electromagnetic wave-shielding material comprising: (1) an electromagnetic wave-shielding layer comprised of: (A) a thermoplastic resin; (B) an aluminum or aluminum alloy; and (C) electrically conductive carbon black; and (2) a surface layer comprised of a thermoplastic resin, wherein: (a) the thermoplastic resin (A) is selected from the group consisting of: (i) polyolefins modified with unsaturated carboxylic acids or derivatives of unsaturated carboxylic acids; (ii) copolymers of ethylene and unsaturated carboxylic acids and/or anhydrides thereof; (iii) copolymers of ethylene and an alkyl acrylate and/or an alkyl methacrylate; (iv) styrene-based resins; (v) vinyl chloride-based resins; (vi) polyamide resins; (vii) polycarbonate resins; and (viii) polyolefins, (b) the aluminum or aluminum alloy is in the form of: (i) particles having a mean size of 250 to 20 mesh; (ii) a fiberous aluminum or a fiberous aluminum alloy having a diameter of from 0.002 to 0.05 mm and a length of 10 mm or less; or (iii) a flake having a surface area of from 0.1×0.1 mm to 5×5 mm, (c) the electrically conductive carbon black has a specific surface area of from 20 to 1,800 m 2 /g, and (d) the proportions of the electrically conductive carbon black and the aluminum or aluminum alloy in the electromagnetic wave-shielding layer are from 5 to 50% by volume, respectively, provided that the total proportion of the carbon black and the aluminum or aluminum alloy is from 10 to 60% by volume, and the difference in solubility parameter between the thermoplastic resin of the surface layer and the thermoplastic resin (A) of the electromagnetic wave-shielding layer is 3.0 or less.