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Electromagnetic wave-shielding materials

  • US 4,508,640 A
  • Filed: 11/23/1982
  • Issued: 04/02/1985
  • Est. Priority Date: 11/24/1981
  • Status: Expired due to Fees
First Claim
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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 m2 /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.

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