Patent GB-929733-A (GB)
Title: Conductive plastic composition and method of making the same
IPC: H01B1/00
Filed: 1959-11-26
Abstract: A granular product for use in moulding conductive articles comprising granules of an electrically conductive composition having their surfaces coated with a thin layer of an electrically conductive substance, said electrically conductive composition consisting essentially of a substantially uniform dispersion of finely divided electrically conductive material in a synthetic resin material, is made by dispersing a finely divided conductive material uniformly in a synthetic resin, forming the resultant dispersion into granules, and coating the surfaces of said granules with an electrically conductive material.  Specified synthetic resins are phenol-aldehyde, urea-formaldehyde, polystyrene, polyethylene, polymethyl methacrylate, vinyl polymers and copolymers, cellulose acetate, silicone resins, polymonochloro trifluoroethylene and polytetrafluoroethylene.  Specified conductive powders are acetylene black, furnace black and metal powders.  Specified conductive materials for coating are silver, nickel and carbon powder optionally applied over adhesion promoting sub-coating, e.g. molybdenum sulphide or graphite.  The examples describe the admixture of:-(1) phenol-aldehyde resin and acetylene black; (2) urea-formaldehyde resin and acetylene black; (3) melamine-formaldehyde and furnace black; (4) polytrifluoro-monochlorethylene and acetylene black; (5) polytetrafluoroethylene and acetylene black; (6) nylon and acetylene black; (7) polyallylphthalate and acetylene black and (8) melamine-formaldehyde and acetylene black; the examples describing the granulation of the resultant dispersions and the coating of the granules.  U.S.A.  Specification 2,761,854 is referred to.ALSO:A granular product for use in moulding conducting articles comprising granules of an electrically conductive composition having their surface coated with a thin layer of an electrically conductive substance, said electrically conductive composition consisting essentially of a substantially uniform dispersion of finely divided electrically conductive material in a synthetic resin material, is made by dispersing a finely divided conductive material uniformly in a synthetic resin, forming the resultant dispersion into granules, and coating the surfaces of said granules with an electrically conductive material.  The coating may be effected by tumbling, chemical deposition or vaporization and condensation under reduced pressure.  Specified synthetic resins are phenol-aldehyde, urea-formaldehyde, polystyrene, polyethylene, polymethylmethacrylate, vinyl polymers and copolymers, cellulose acetate, polymonochlorotrifluoroethylene, silicone resins and polytetrafluoroethylene.  Specified conductive powders are acetylene black, furnace black and metal powders.  Specified coating materials are silver, nickel and carbon powder optionally applied over adhesion promoting subcoatings, e.g. molybdenum sulphide or graphite.  The examples describe the admixture of: (1) phenol-aldehyde resin and acetylene black; (2) urea-formaldehyde resin and acetylene black; (3) melamine-formaldehyde resin and furnace black; (4) polytrifluoro-monochlorethylene and acetylene black; (5) polytetrafluoroethylene and acetylene black; (6) nylon and acetylene black; (7) polyallyl phthalate and acetylene black; and (8) melamine-formaldehyde resin and acetylene black, the products being: (1), (4), (5), (6), (7) and (8) milled with molybdenum sulphide and then with finely divided silver; (2) milled with finely divided silver; and (3) milled with molybdenum disulphide and then with finely divided nickel, the products being moulded into contact elements.  U.S.A. Specification 2,761,854 is referred to.