Anchoring loops of fibers needled into a carrier sheet
Methods of forming a loop product are provided. One method includes (a) needling polymeric fibers through a substrate to form hook-engageable loop structures of the fibers extending from one surface of the substrate; and then (b) using heat and pressure to locally soften and bond polymer of the fibers directly to the substrate and adjacent fibers, thereby anchoring the loop structures to resist fiber pullout under fastening loads.
1 . A method of forming a loop product, the method comprising
needling polymeric fibers through a substrate to form hook-engageable loop structures of the fibers extending from one surface of the substrate; and then
applying heat and pressure to locally soften and bond polymer of the fibers directly to the substrate and adjacent fibers, thereby anchoring the loop structures to resist fiber pullout under fastening loads.
2 . The method of claim 1 wherein the applying step includes applying pressure locally to discrete areas of the carded web.
3 . The method of claim 2 wherein the applying step is performed multiple times.
4 . The method of claim 2 wherein pressure is applied by a plurality of point contacts.
5 . The method of claim 2 wherein pressure is applied at a nip.
6 . The method of claim 5 further comprising preheating the needled substrate prior to delivering it to the nip.
7 . The method of claim 6 wherein preheating is performed using infrared energy.
8 . The method of claim 5 wherein one roll of the nip is covered with a card cloth.
9 . The method of claim 1 wherein heating and applying pressure are performed simultaneously.
10 . The method of claim 1 wherein heating and applying pressure are performed sequentially.
11 . The method of claim 1 wherein the fibers comprise bicomponent fibers.
12 . The method of claim 11 wherein the bicomponent fibers comprise core-sheath fibers wherein the sheath has a lower melting point than the core.
13 . The method of claim 12 wherein the core is a polyester and the sheath is a copolyester.
14 . The method of claim 12 wherein the sheath is formed of a polymer having a melting temperature of about 110 degrees C.
15 . The method of claim 11 wherein the fibers comprise a blend of bicomponent fibers and single component fibers.
16 . The method of claim 15 wherein the blend includes between about 15 and 30 percent bicomponent fibers, by weight.
17 . The method of claim 1 wherein the substrate comprises a polymer film.
18 . The method of claim 1 wherein the substrate comprises a scrim.
19 . The method of claim 1 wherein the substrate comprises paper.
20 . The method of claim 1 wherein the needling step comprises elliptical needling.
21 . The method of claim 1 further comprising embossing the loop product after anchoring the loop structures.
22 . The method of claim 1 wherein the needling step comprises needling into a moving support.
23 . The method of claim 22 wherein the moving support comprises a brush apron.