Patent GB-1391262-A (GB)
Title: Conductive bicomponent fibres
IPC: D06M11/83
Filed: 1971-06-22
Abstract: 1391262 Conductive bicomponent fibres IMPERIAL CHEMICAL INDUSTRIES Ltd 5 June 1972 [22 June 1971] 29180/71 Headings DIP and D1W A conductive bicomponent fibre or filament comprises two synthetic polymeric components arranged in distinct zones across the cross-section of the fibre and being continuous along the length of the fibre, a first component being derived from a fibre-forming polymer and the second component being derived from a polymeric material having a lower melting point than the fibre-forming polymer, and being located so as to form at least a portion of the peripheral surface of the fibre, the second component being fused to at least a portion of a conductive coating located on the surface of the fibre. The coating may be a metallic film, e.g. silver or nickel, or may comprise graphite. The components of the bicomponent fibre are preferably arranged in a sheath and core relationship but may be side-by-side e.g. in a trilobal fibre. Suitable bicomponent fibres include poly-(epsilon caprolactam)/poly(hexamethylene adipamide) fibres, poly-(epsilon caprolactam-hexamethylene adipamide)/polyhexamethylene adipamide) fibres, poly (ethylene terephthalate-ethylene adipate)/poly (ethylene terephthalate) fibres, poly (ethyleneterephthalate-ethylene isophthalate)/poly (ethylene terephthalate) fibres, and polypropylenepoly (ethylene terephthalate) fibres, the first mentioned component being the lower melting point one. Preferably the lower melting point component is derived from a fibreforming polymeric material. The fibre may be in the form of a fabric or carpet. The conductive bicomponent fibre is made by providing the bicomponent fibre with a conductive coating, and subsequently heating to a temperature sufficient to fuse the second component to at least a portion of the conductive coating, but below the melting point of the fibre-forming polymer of the first component. A metallic coating may be provided on the bicomponent fibre by chemical deposition, electro-deposition, vacuum vaporisation, or spraying with metal powder. Where the lower melting component is a polyamide or copolyamide the heating step may be carried out in the presence of steam under pressure. In a preferred process, the bicomponent fibre is knitted into a fabric which is then coated with a conductive material, heated to effect fusion as well as setting of the knitted structure and subsequently deknitted to produce a crimped conductive fibre. In examples (1) a knitted panel formed from a sheath-core monofilament having a core derived from poly-hexamethylene adipamide containing 0.3% of titanium dioxide and a sheath derived from a copolyamide containing 70% of hexamethylene adipamide units and 30% of caprolactam units, (the sheath copolyamide having a melting point of 195‹C and the core 264‹C is coated with silver by chemical deposition from Tollen's reagent (ammoniacal silver nitrate solution), the degreased panel first being immersed in formaldehyde solution and then in the ammoniacal silver nitrate solution, dried in an air oven at 80‹C for 30 mins and heated at 200‹C for about 12 mins in a stream of nitrogen; (2) example 1 was repeated except that the fabric was coated with nickel by chemical deposition, after first treating the fabric by immersion in acidified aqueous palladium chloride solution; (3) as (1) except that the fabric is coated with graphite by immersion in a 12% graphite dispersion; (4) as (1) except that the fabric was silver coated by deposition in a vacuum of 10<SP>-4</SP> Torr.