Continuous production of nonwoven tubular webs from thermoplastic fibers and products

Abstract

A process is provided for the continuous production of nonwoven webs in the form of a flexible tube from thermoplastic fibers, spinning the fibers continuously from a melt onto a rotating mandrel and continuously withdrawing the web from the mandrel in the form of a flattened tube. Density of the web is controlled by controlling the distance between the rotating mandrel and the orifices of the spinning die through which the molten polymeric material is spun, and by controlling the diameter of the fibers. If the spinning of the fibers is continuous, the flattened tubular web can be formed in a continuous length. Control of the spinning rate in relation to the diameter of the mandrel and the rate of withdrawal of the tubular web from the mandrel controls the thickness of the web. The web drawn off the mandrel can be used as a tube, or slit lengthwise and opened out, or collapsed onto itself, for use as a double layer sheet. The process is particularly adapted for forming filter elements and for forming webs of great width, which would be very costly or impractical to produce using conventional spinning dies of length equal to the width of the web.

Dependencies are inferred from the claim text.