Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – To produce composite – plural part or multilayered article
Patent
1984-03-16
1986-04-15
Lilling, Herbert J.
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
To produce composite, plural part or multilayered article
264279, 26432818, 343 18A, 428197, 428246, 428252, 523137, 524413, 524440, 524781, 252512, C08K 702, C08L 2706, C08L 5502, H01B 718
Patent
active
045826617
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE ART
This invention relates to a composition for use in electromagnetic wave shielding suitable for electronic apparatuses, and electronic parts, etc. and having an excellent in injection moldability.
BACKGROUND OF THE ART
In order to industrially manufacture at low cost an interface bus cable for connecting electronic components such as peripheral units for personal computers while avoiding an electric wave leaking, it is necessary to insulate the connection between cores and terminals of the bus cable and to cover the thus insulated connection with an electromagnetic shielding material by injection molding. However, shielding material heretofore proposed does not have a sufficient fluidity above the melting point or softening point of a base polymer. Hence, there was a problem in that it was difficult to properly place the shielding material by injection molding techniques so that the shielding material would assume the shape defined by a metal mold or in that the molded material would not have a smooth surface. It was impossible to obtain properly shaped shielding members having a smooth surface.
DISCLOSURE OF THE INVENTION
In view of the problems described above, this invention proposes a novel composition for use as electromagnetic wave shielding having both an excellent electromagnetic wave shielding ability and an injection moldability. The composition proposed according to the invention comprises at least one kind of a suspension or embedding agent selected from a group consisting of plasticized vinyl chloride resin, and acrylonitrile-butadiene-styrene resins and fibers suspended or embedded in said agent, said fibers consisting of copper or of a copper alloy and having a diameter of 1-100 .mu.m and a length of 0.5-10 mm. The fiber content contained in the composition amounts to 30-70% by weight of the composition.
The plasticized vinyl chloride resin used by the invention may be, for example a vinyl chloride homopolymer, a vinyl chloride copolymer, or an internally plasticized vinyl chloride copolymer, etc, plasticized by the use of a plasticizer or an organic high polymer compatible with vinyl chloride resin. A composition is particularly useful for the present purposes if it has a vicosity, at a temperature of 180.degree. C., measured by a Brabender plastograph, in the range of 50-3,000 m-g, more particularly 100-2,000 m-g. The unit: m-g is used in the present disclosure for all viscosity values as measured by said plastograph at said temperature condition. more particularly 100-2,000 m-g is suitably used. Such a composition shows an excellent injection moldability in a state in which metal fibers to be described below, are compounded in large quantities.
The above-mentioned vinyl chloride homopolymer may be produced by a conventional known polymerization process such as an ordinary suspension polymerization, an emulsion polymerization, a bulk polymerization or a solution polymerization. A homopolymer is particularly suitable for the present purpose if its mean degree of polymerization (P) is within the range of 300-2,000, especially 400-1,100, because it has desirable injection molding features.
The above-mentioned vinyl chloride copolymer may be produced by an above mentioned conventional process, and has the characteristic in that (a) the vinyl chloride content is at least 50% by weight and particularly at least 80% by weight, (b) the viscosity is lower than that of vinyl chloride homopolymer, and (c) the mean degree of polymerization is within the range of 300-2,000 and especially 400-1,100. Such vinyl chloride copolymer includes (1) copolymers of vinyl chloride with at least one kind of monomer capable of effecting radical polymerization with vinyl chloride, for example, olefin, diene, unsaturated carboxylic acid and its esteric derivatives, unsaturated nitryl, aromatic vinyl and it derivatives; (2) graft polymers obtained by grafting upon vinyl chloride homopolymer or the above vinyl chloride copolymer at least one kind of monomer capable of effecting radical polymerizat
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Derwent Abst. 44429 E/22 J57065754 (4-1982).
Ito Hirotaka
Kusui Akio
Dainichi-Nippon Cables Ltd.
Fasse W. G.
Kane, Jr. D. H.
Lilling Herbert J.
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