Patent GB-1337442-A (GB)
Title: Non-woven-fabric
IPC: D04H13/00
Filed: 1971-04-19
Abstract: 1337442 Non-woven fabric POLYMER PROCESSING RESEARCH INSTITUT Ltd and NIPPON PETROCHEMICALS CO Ltd 19 April 1971 [13 Feb 1970] 21710/71 Heading D1R [Also in Division B5] A non-woven fabric, e.g. for making blankets, clothing or carpet backing comprises a foundation layer comprising at least one laminate of a warp web and a weft web, each web being formed by elongate split fibers prepared from a splittable unidirectionally stretched polymer film e.g. polyolefin, and at least one layer of relaxed fibers (i.e. fibers under no tension) bounded to one or each side of the foundation layer; the relaxed fibers of the layer being entangled with the fibers of the foundation layer. In a method of making the fabric, the foundation layer is formed by cutting the weft web at intervals corresponding to the width of the warp web, laying the out portions across the warp web and fixing the fibers of the webs by an adhesive, and by entangling the fibers of the relaxed layer(s) with the foundation layer by needle punching. The fabric of Fig. 2b is formed by the apparatus of Fig. 3. A foundation layer 4 is supplied from a roll 3 by pinch rollers 5, 5' onto an endless screen 9. A layer of filaments is oversupplied onto the layer 4 from a roll 11 via an air passage 13. A suction box 10  is positioned below the screen. Subsequently a second foundation layer 16 and a second layer 17 of filaments is supplied to overlie the layer 4. The fabric is then passed in sequence between needle punching machines 20, 20', feed pinch rollers 21, 21', a hot air chamber 22 where an adhesive binder applied to the foundation layers in advance is heated, and press rollers 23, 23' to effect bonding of the filaments to the foundation layers by pressure-adhesion. The adhesive binder may be in the form of a powder, emulsion, solution, or non-stretched film. When acrylic fibers are used as the filament layers a liquid adhesive binder containing a copolymer of acrylonitrile and acrylamide is suitable. The finished product may be immersed in or sprayed with adhesive for use as a carpet backing. In one example of forming a fabric as shown in Fig. 1b the split fiber webs are prepared from a tubular film of high density polyethylene containing dark brown pigments, stretched longitudinally to 4 times its length and cut longitudinally. The two sheets thus formed are laid side by side and then stretched longitudinally up to 9 times as long as the original length under heat at 120C. The sheets are then made into split fiber webs by passing over splitting means. Subsequently the webs are passed over steam heated drums while allowing the fibers to shrink. To prepare the laminate, the split fiber webs are extended transversely by a coil spring extending transverse to the web with its ends moving along two diverging tracks. The webs are pasted with an emulsion of 60% vinyl acetate and 40% ethylene, and dried. The web (i.e. weft web) is supplied in a longitudinally moving direction transverse of (at right angles or obliquely) and above the other (or warp) web and is cut into lengths corresponding to the warp web width. The lengths fall onto the warp web, and may overlap. The laminate is then heated by passing over a heated drum to join together the warp and weft webs by heating and pressing. Five layers of crimped acrylic tows dyed in dark brown by a cationic dye and a foundation layer provided 'by two superimposed laminates are pressed into the product of Fig. 1b using the apparatus of Fig. 3.  The layer of relaxed fibers may comprise one or a mixture of the following (I) a carded web of staple fibers, a layer of staple fibers prepared from filament tows, or a band of a plurality of slivers of staple fibers arranged in parallel, (2) a randomly-laid flat sheet-like entangled layer of staple fibers, (3) a flat layer of filaments in a relaxed state prepared by warping non twisted or loosely-twisted filament yarns to a constant width and oversupplying the yarns to a travelling screen, (4) a flat layer of filaments or a web of split fibers in a relaxed state prepared by extending a filament low or a web of split fibers thinly and approximately uniformly to a larger width and over supplying the tow or web on a travelling screen and (5) an extended flat layer of fibers in a relaxed state consisting of filament yarns, filament tows and a web of split fibers, the yarns, tows or fibers having a latent crimpability or having been crimped.  The fibers may be hydrophilic fibers e.g. viscose fibers, or may comprise the same material as that used for the foundation layer. When the relaxed fiber layer comprises an extended tow of crimped filaments, the filaments may be fluffed by cutting after needle punching.