Methods of forming ultra-fine fibers and non-woven webs

Abstract

A nonwoven web product including ultra-fine fibers is formed utilizing a spunbond apparatus that forms multicomponent fibers by delivering first and second polymer components in a molten state from a spin pack to a spinneret, extruding multicomponent fibers including the first and second polymer components from the spinneret, attenuating the mulicomponent fibers in an aspirator, laying down the multicomponent fibers on an elongated forming surface disposed downstream from the aspirator to form a nonwoven web, and bonding portions of at least some of the fibers in the nonwoven web together to form a bonded, nonwoven web product. The multicomponent fibers can include separable segments such as islands-in-the-sea fibers, where certain separated segments become the ultra-fine fibers in the web product. In addition, carbon tubular fibers can be formed by extruding island-in-the-sea fibers including polyacrylonitrile or pitch sheath segments in the fibers, separating the segments of the fiber, and converting the polyacrylonitrile of pitch to carbon by a carbonization process.