LOOP ELEMENT OF HOOK/LOOP FASTENER AND METHOD OF MAKING SAME

Abstract

A hook-and-loop fastener has a hook element comprising a substrate having a face from which projects a multiplicity of hooks and a loop element formed by of a fiber web. The fiber web is formed by a homogenous mixture of first multicomponent filaments each formed by a high-melting-point polymer and a low-melting-point polyolefinic polymer and second polyolefinic monocomponent filaments. The first filaments constitute between 20% and 80% by weight of the mixture. The fiber web has a face formed with a patterned array of dense bonded regions of a predetermined small thickness interspersed with less dense open regions of a predetermined big thickness substantially greater than the small thickness of the small thickness interspersed with less dense open regions of a predetermined big thickness substantially greater than the small thickness of the bonded regions so that the filaments of the open regions form loops.

Claims

1. A hook-and-loop fastener comprising: a hook element comprising a substrate extending generally in a plane and having a face from which projects a multiplicity of hooks; and a loop element comprised of a fiber web extending in a longitudinal direction and a transverse direction perpendicular thereto, and having a thickness measured transversely to a plane of the directions, the fiber web being formed by a homogenous mixture of first multicomponent filaments each formed by a high-melting-point polymer and a low-melting-point polyolefinic polymer and second polyolefinic monocomponent filaments, the first filaments constituting between 20% and 80% by weight of the mixture.

2. The fastener defined in claim 1, wherein the fiber web has a face formed with a patterned array of dense bonded regions of a predetermined small thickness interspersed with less dense open regions of a predetermined big thickness substantially greater than the small thickness of the bonded regions, whereby the open filaments of the open regions form loops.

3. The fastener according to claim 1, wherein the mixture is 30 wt % to 50 wt % of the mixture.

4. The fastener according to claim 2, wherein the mixture is wholly formed of the first and second filaments.

5. The fastener according to claim 1, wherein the second polymer and/or the third polymer is polypropylene, a polypropylene copolymer, polyethylene, or a polyethylene copolymer.

6. The fastener according to claim 5, wherein both the second and third polymers are the same polymer.

7. The fastener according to claim 1, wherein a melting point of the second polymer and a melting point of the third polymer are within 5 K of one another.

8. The fastener according to claim 1, wherein the second polymer and the third polymer have a melt flow index between 20 g/10 min and 500 g/10 min.

9. The fastener according to claim 1, in that the first polymer is polyethylene terephthalate.

10. The fastener according to claim 1 wherein the fiber web has a filament density in the open regions between 1.0×10.sup.10 filaments/m.sup.3 and 1.5×10.sup.10 filaments/m.sup.3.

11. The fastener according to claim 1, wherein the first filaments and/or the second filaments have a nonround cross-section.

12. The fastener according to claim 1, wherein the fiber web has an average fineness or titer of 1 dtex to 8 dtex.

13. The fastener according to claim 1, wherein the fiber web has a surface density between 30 and 60 g/m.sup.2.

14. The fastener according to claim 1, wherein the open regions are arrayed in a regular pattern and include convex first regions and convex second regions of lesser area than the first regions.

15. The fastener according to claim 14, wherein the first and second regions are of geometrically similar shapes.

16. The fastener according to claim 15, wherein the first regions are elongated in one of the directions and the second regions are elongated in the other of the directions, the first regions overlapping one another in both the one direction and the other direction.

17. The fastener according to claim 15, wherein the first and second regions are substantially elliptical and have respective first and second major and minor axes, the first major axes being parallel to one another, the second major axes being parallel to one another and generally perpendicular to the first major axes.

18. The fastener according to claim 15, wherein the bonded regions are continuous and the first and second regions are each wholly surrounded by the bonded regions.

19. The fastener according to claim 15, wherein the first and second regions are spaced in the plane from one another by a minimum of 0.25 mm to 0.7 mm.

20. The fastener according to claim 1, wherein the bonded regions arrayed in a line pattern constituted by a first group of parallel lines and second group extending at an acute angle to the first group of parallel lines to form a plurality of four-sided rhombic cells, the line pattern further having an open elliptically arcuate line in each of the cells tangentially engaging all four sides of the respective cell.

21. The fastener according to claim 20, wherein the lines of one of the first and second groups are discontinuous and do not touch lines of the other of the first and second groups.

22. The fastener according to claim 20, wherein each of the rhombic cells holds a respective one of the open elliptically arcuate lines.

23. The fastener according to claim 1, wherein the bonded regions form between 15% and 30% of a surface area of the one face of the fiber web.

24. A method of making the web of claim 1, the method comprising the steps of sequentially: forming the fiber web; and thermally consolidating the fiber web by air-through bonding and by thermal calendering.

25. The method according to claim 24, wherein the air-through bonding takes place before the thermal calendering.

26. The method according to claim 24, further comprising the step of: carding the fiber web prior to thermal consolidation.

27. A hook-and-loop fastener comprising: a hook element comprising a substrate extending generally in a plane and having a face from which projects a multiplicity of hooks; and a loop element comprised of a fiber web extending in a longitudinal direction and a transverse direction perpendicular thereto, and having a thickness measured transversely to a plane of the directions, the fiber web being formed by a homogenous mixture of first multicomponent filaments each formed by a high-melting-point polymer and a low-melting-point polyolefinic polymer and second polyolefinic monocomponent filaments, the first filaments constituting between 20% and 80% by weight of the mixture.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0060] The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

[0061] FIG. 1 is a cross section through a nonwoven according to the invention;

[0062] FIG. 2 shows a top view of a nonwoven according to the invention with a first pattern;

[0063] FIG. 3 is a top view of a nonwoven according to the invention with a second pattern; and

[0064] FIG. 4 shows a schematic representation of a production method according to the invention.

SPECIFIC DESCRIPTION OF THE INVENTION

[0065] FIG. 1 shows a nonwoven 1 according to the invention comprised of a fiber web 2 that in accordance with the first aspect of the invention is a homogeneous filament mixture with first filaments and second filaments. The first filaments in this embodiment 50 wt % of the filament mixture and is made of a bicomponent filament with polyethylene terephthalate (PET) with a weight fraction of 60% (30% of the filament mixture, corresponding to 3.3 dtex) as the first polymer and polyethylene (PE) with a weight fraction of 40% (20% of the filament mixture, corresponding to 2.2 dtex) as the second polymer formed. The melting point of the polyolefinic polyethylene is below that of PET. Furthermore, the filament mixture contains 50% by weight (corresponding to 1.9 dtex) of one polypropylene (PP) monofilament.

[0066] The nonwoven forms a textile web extending in a longitudinal or machine direction MD and a transverse direction CD perpendicular thereto. At right angles to this web plane, the nonwoven has an overall height or thickness H formed by big and small thicknesses d.sub.1 and d.sub.2 that differ locally on the textile web. Thus the nonwoven layer has a pattern of open regions 3 with a big thickness d.sub.1, which are surrounded by bonded regions 4 with a small thickness d.sub.2.

[0067] In the bonded regions 4, the synthetic-resin filaments 5 of the batt 2 are compressed and the fibers or filaments are connected to one another by partially melting them together. Thus in the bonded regions 4, almost all of the filaments 5 there are firmly connected together at least one point within the fibrous web 2 and thus held securely.

[0068] In the open regions 3, the filaments 5 are only loosely attached at random crossing or connection points 6. These connections 6 cannot prevent the individual filaments 5 from being pulled out. However, they serve to maintain the structure of the open region 3, in particular for the formation of the preset big height d.sub.1. This is selected so a given filament fineness, surface density and average filament length confer a preferred filament density of 1.2×10.sup.10 filaments/m.sup.3 in the open regions 3. These open regions 3 are used to engage hooks 7 of a hook tape 8 embedded in a substrate 8a. The hook tape 8 forms together with the nonwoven 1 a hook-and-loop fastener, the nonwoven 1 with the open regions 3 forming the loop face.

[0069] FIG. 2 shows a first possible pattern of the open regions 3 and bonded regions 4. The open regions 3 form a regular pattern of convex first regions 9a and convex second regions 9b. The first regions 9a are ten times greater in area than the second regions 9b. They are elliptical and geometrically similar to one another and arrayed in a grid along a first direction L.sub.1 and in a second direction L.sub.2 perpendicular thereto. The first regions 9a overlap in the first direction L.sub.1 as well as in the second direction L.sub.2. In this embodiment, there is between the first direction L.sub.1 and the longitudinal direction MD and between the second direction L.sub.2 and the transverse direction CD an angle α of 1.2°. This slight inclination can produce technical advantages, especially when manufacture uses profile rollers.

[0070] The first regions 9a are each elliptical and extend parallel to one another extending along respective first major axes a.sub.1 of about 7 mm and first secondary axes a.sub.2 of about 5 mm. The second regions 9b are also elliptical with second major axes b.sub.1 of approximately 2.7 mm and second minor axes b.sub.2 of about 1.3 mm. The major axes a.sub.1 of the regions 9a are roughly perpendicular to the major axes b.sub.1 of the regions 9b. The grid size of the first regions 9a with one another or the second regions 9b below one another are each (center to center) s.sub.2=9.6 mm in the second direction L.sub.2 and s.sub.1=8.5 mm in the first direction L.sub.1. In this pattern the bonded regions 4 cover an area of about 20% and the open regions the remaining area of at least 70% and preferably 80% of the web 2. The total area of only the first regions 9a is equal to about 70% of the total area of the workpiece 2. The minimum distance d between two adjacent first regions 9a or the first regions 9a and adjacent second regions 9b is about 0.4 mm.

[0071] FIG. 3 shows an alternative pattern in accordance with another inventive aspect of the present application. The bonded regions 4 thereby form a line pattern. The line pattern includes a first group of parallel lines 10a as well a second group of parallel lines 10b inclined at an angle β with respect to the lines of the first group 10a. The lines of the first group 10a and the lines of the second group 10b are interrupted in such a way as to form breaks or interruptions at the intersections 11, which are not bonded but form open regions 3.

[0072] The lines 10a and 10b are continuous other than at the intersections 10. The lines 10a of the first group and the lines 10b of the second group are each set equidistantly and form diamond-shaped or rhombic cells 12 whose corners form the intersection points 11. The sides of the rhombic cells 12 are formed by uninterrupted sections of lines 10a of the first group and lines 10b of the second group.

[0073] Each of the diamond-shaped cells 12 holds an incomplete elliptical arc 13 of the line pattern. This arc 13 touches the lines 10a and 10b defining the cells 12 tangentially. The elliptical arc 13 defines a complete quadrant between the contact points of two adjacent edge lines.

[0074] A cushion-shaped portion 14 of an open region 3 is located within the elliptical arc 13 where the lines 10a and 10b are interrupted at the intersection 11 and form regions 15 with two straight sides and an arcuate base between them. The elliptical arc 13 delimits a cushion-like region 14 of the respective open region 3, that is connected at the intersection 11 to open regions 15 outside the elliptical arcs 13 in adjacent cells 12. The major diameter b of the cushion-like section b in this example is about 12 mm. The height h of the cushion 14 is the maximum height of the elliptical arc 13, that is about 8 mm.

[0075] FIG. 4 schematically illustrates a production method according to the invention. In a first step I a filament mixture, in particular a homogeneous filament mixture of a multicomponent filament and a low-melting-point monofilament is produced. The staple fibers 16 laid in this way are initially fed to a carding machine 17 and roughly aligned there. The carded fiber web 18 is then subjected to a first thermal consolidation II by air-through-bonding. The carded fiber web 18 is transferred by a suction roller 19 to a large drum 20 into which continuous streams 21 of hot air are aspirated. The temperature of the hot air stream 21 is set such that the filaments of the fiber web 18 melt on their surface and at random contact points 6 connect with one another. Via a second roller 22, which is optionally cooled, the preconsolidated fiber web 23 is pulled off the drum 20.

[0076] Then the preconsolidated fiber web 23 is for thermally calendered at III in the nip between two rollers 24, of which at least one is profiled. The preconsolidated fiber web 23 is compressed by appropriate temperature control of the rollers 24 at least locally—in the bonded regions 4—and further consolidated. This forms the above-described pattern of open regions 3 and bonded regions 4. The pattern of the profiled rollers 24 can emboss the preconsolidated web 23 with the desired pattern. The finished nonwoven 1 can then be wound up into a roll 25.