Embossing loop materials
Methods are provided for forming loop fastener products. One method includes applying heat and pressure to a carded web in a manner which fuses fibers on a back side of the web, thereby forming a bonded web, and then embossing the bonded web to raise discrete regions of the web, each raised region containing hook-engageable fiber portions that are exposed for engagement on a front side of the web and fused on the back side of the web within the region. Another method includes placing staple fibers on a back side of a substrate; needling the staple fibers through the substrate to form a composite, thereby forming loop structures extending from a front side of the substrate; applying heat and pressure to the composite in a manner which fuses fibers on the back side of the substrate while protecting the loop structures on the front side of the substrate; and embossing the composite.
1 . A method of forming a loop fastener product, the method comprising
applying heat and pressure to a layer of staple fibers disposed on a substrate, in a manner which fuses fibers to the substrate, thereby forming a composite; and then
embossing the composite to raise discrete regions of the composite, each raised region containing hook-engageable fiber portions that are exposed for engagement on a front side of the composite and fused within the raised region.
2 . The method of claim 1 comprising, prior to applying said heat and pressure, needling the staple fibers through the substrate to form loop structures of the fibers extending from the front side of the substrate.
3 . The method of claim 2 comprising, while applying the heat and pressure, protecting the loop structures on the front side of the substrate from application of the pressure.
4 . The method of claim 2 wherein needling the fibers comprises moving a bed of needles in an elliptical path.
5 . The method of claim 2 wherein needling the fibers comprises needling into a moving support.
6 . The method of claim 5 wherein the moving support comprises a brush apron.
7 . The method of claim 1 wherein the pressure is applied to only discrete areas of the composite.
8 . The method of claim 7 wherein the pressure is applied by a plurality of point contacts.
9 . The method of claim 1 wherein the pressure is applied multiple times, sequentially.
10 . The method of claim 1 wherein the pressure is applied at a nip between counter-rotating rolls.
11 . The method of claim 10 further comprising preheating the carded web prior to delivering it to the nip.
11 . The method of claim 10 wherein one roll of the nip is covered with a card cloth carrying a field of pins that apply the pressure to the fibers.
12 . The method of claim 11 wherein the card cloth comprises a field of pins with an effective pin density at the substrate of between about 20 and 50 pins per square centimeter.
13 . The method of claim 1 wherein heat and pressure are applied simultaneously.
14 . The method of claim 1 wherein the fibers comprise bicomponent core-sheath fibers with sheaths of material having a lower melting point than their cores.
15 . The method of claim 1 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 . A loop fastener product comprising
a substrate carrying a field of staple fibers exposed on a front surface of the substrate for releasable engagement by hooks;
the substrate embossed to define a pattern of raised areas on the front surface and corresponding recessed areas on an opposite surface;
wherein each raised area comprises several exposed fibers that are anchored at bond points within the raised area.
19 . The product of claim 18 wherein the fibers extend through the substrate to form loops on the front surface.
20 . The product of claim 19 wherein the fibers are anchored at the opposite surface of the substrate.
21 . The product of claim 18 wherein the opposite surface is free of said fibers.
22 . The product of claim 18 wherein the fibers include bicomponent fibers.
23 . The product of claim 22 wherein the fibers are anchored by material of sheaths of the bicomponent fibers.
24 . The product of claim 18 wherein the pattern defines an array of raised areas with common boundaries.
25 . The product of claim 24 wherein the raised areas comprise hexagonal cells.
26 . The product of claim 24 wherein the boundaries are of a width of less than about 1.0 millimeter.
27 . The product of claim 24 wherein the boundaries form only about 20 percent of a total area of the front surface, the raised areas forming about 80 percent of the total area.