Sheath-core spinning of multilobal conductive core filaments

Claim 1

In a process for melt-spinning a sheath-core fiber wherein one polymer composition constitutes the sheath component and a different polymer composition constitutes the core component and the core cross-section has three or more lobes, which process comprises simultaneously extruding both molten component compositions, through a spinning orifice with the sheath component completely surrounding the core component, the improvement comprising, maintaining the core cross-sectional configuration by 1) feeding the molten core component composition in the desired multilobal cross-section through a channel opening above a spinneret capillary, 2) feeding the molten sheath component from all directions against the core along the periphery of the entrance to the spinneret capillary to completely surround the core component, 3) controlling the flow of molten sheath component composition at spaced sections along the periphery of the spinneret capillary entrance by enlarging the passageway for the sheath polymer only in those sections leading to zones between lobes to allow more flow to zones between the lobes than to zones at the lobes, and 4) solidifying the molten components after leaving the spinneret orifice to form the sheath-core fiber.