Multilayer, liquid-proof nonwoven fabric for roofing etc.

摘要

A multilayer, liquid-tight nonwoven fabric (10) in the form of a composite material with at least two layers comprises spun-bonded fabric (12, 16) and melt-blown fabric (14), bonded/welded together by thermobonding at discrete points. The starting material for both components consists of polymer granules which are processed to give a liquid melt from which the fibres/filaments for the layers are made. The fibres (18) contain layer(s) of additives (20, 22) which reduce the wettability of the fibre surface by liquids with a surface tension so low that their contact angle without the additives would be from above 0 to below 90 deg , thus preventing penetration of fabric (10) by liquid. Additives (20, 22) are distributed throughout the fibre cross-section, and also on the fibre surface (18) as a result of diffusion. Also claimed is a process for the production of spun-bonded or melt-blown layers for this fabric, comprising (a) production of additive granules containing "FX 18 01" (RTM: fluorocarbon compound), (b) mixing these with pure polymer granules and (c) processing the mixture to obtain the required melt liquids.