Loop-forming closure element for hook-and-loop fasteners and method for the production of a closure element

Abstract

A loop-forming closure element for hook-and-loop fasteners embodies an embossed nonwoven material having continuous fibers of a spun bonded fabric and carded staple fibers. The continuous fibers and the staple fibers are intertwined and form a common nonwoven material layer as a fiber blend.

Claims

1. A loop-forming closure element for hook-and-loop fasteners comprising an embossed nonwoven material layer that comprises, continuous fibers of a spun bonded fabric and carded staple fibers; wherein the continuous fibers and carded staple fibers are intertwined, where the intertwined continuous fibers and carded staple fibers together embody the embossed nonwoven material layer as a fiber blend; wherein a proportion of the continuous fibers to a proportion of carded staple fibers changes across a thickness of the embossed nonwoven material layer; and wherein the carded staple fibers protrude from at least one side of the embossed nonwoven material layer.

2. The closure element according to claim 1, wherein the embossed nonwoven material layer is formed entirely of the continuous fibers and the carded staple fibers.

3. The closure element according to claim 1, wherein the embossed nonwoven material layer is cold embossed without the continuous fibers fusing with the carded staple fibers.

4. The closure element according to claim 1, wherein the embossed nonwoven material layer has a mass per unit area between 20 g/m.sup.2 and 50 g/m.sup.2.

5. The closure element according to claim 1, wherein the embossed nonwoven material layer is laminated with a carrier film.

6. The closure element according to claim 5, wherein the embossed nonwoven material layer and the carrier film are laminated with an adhesive applied in a pattern.

7. The closure element according to claim 1, wherein the embossed nonwoven material layer comprises linear or wavy impressions.

8. The closure element according to claim 1, wherein the continuous fibers are formed of polyolefin, in particular polypropylene.

9. The closure element according to claim 1, wherein the staple fibers are formed of a polyolefin or a polyester.

10. The closure element according to claim 1, the carded staple fibers protrude from both sides of the embossed nonwoven material layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further features and advantages of the invention will become apparent from the description of exemplary embodiments that follows, with reference to the attached figures. Therein:

(2) FIG. 1A shows a loop-forming closure element for hook-and-loop fasteners,

(3) FIG. 1B shows staple fibers protruding from both sides of the nonwoven materials layer of the loop-forming closure element of FIG. 1.

(4) FIG. 2 shows method steps for producing the loop-forming closure element depicted in FIGS. 1A and 1B;

(5) FIG. 3 shows method steps for producing the loop-forming closure element depicted in FIGS. 1A and 1B.

(6) FIG. 4 shows an embossing structure on the surface of a roller used in the method according to FIG. 2; and

(7) FIG. 5 shows an adhesive pattern for laminating a nonwoven material with a carrier film.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(8) The following is a detailed description of example embodiments of the invention depicted in the accompanying drawings. The example embodiments are presented in such detail as to clearly communicate the invention and are designed to make such embodiments obvious to a person of ordinary skill in the art. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention, as defined by the appended claims.

(9) FIG. 1B shows a loop-forming closure element, which forms the female part of a hook-and-loop fastener, wherein loops for connection with gripping hooks of a nonwoven material 1 are formed. The nonwoven material 1 has impressions 2 on a first side and, on one side, is formed of continuous fibers 3 of a spun bonded fabric and carded short-staple fibers in the form of staple fibers 4. The continuous fibers 3 and the staple fibers 4 are intertwined and form a common nonwoven material layer comprising a fiber blend. While the continuous fibers 3 ensure good stability and strength of the nonwoven material 1, the staple fibers 4 provide a particularly soft surface.

(10) As is clear in FIG. 1B, the staple fibers 4 extend across the entire thickness of the nonwoven material 1, although as shown in FIGS. 1A and 1B, the proportion of staple fibers on the first side of the nonwoven material 1 provided with impressions 2 is somewhat higher, for production-related reasons.

(11) The nonwoven material 1 is laminated with a single-layer carrier film 6 by means of adhesive 5.

(12) Between the impressions 2, the continuous fibers 3 and the staple fibers 4 protrude from the first side of the nonwoven materials 1, partially forming loops, and can therefore be used for a connection with gripping hooks. As shown in FIG. 1B, at least a few staple fibers protrude from the other or second side of the nonwoven materials forming nonwoven materials layer 1. An interconnection at the continuous fibers 3 as well as at the staple fibers 4 is possible. Gripping hooks can engage deeply into the nonwoven material 1 specifically at the edges of the impressions 2. In addition, the impressions 2 bring about a stabilization of the nonwoven material 1.

(13) At the impressions 2, the continuous fibers 3 and the staple fibers 4 are deformed without fusing with one another. The mass per unit area of the nonwoven material 1 is preferably between 20 g/m.sup.2 and 50 g/m.sup.2.

(14) As explained in detail in the following, the impressions 2 are produced using a roller 7 (FIG. 2). The surface structure of the roller 7 provided for the embossing is depicted in FIG. 4. The structure that is shown therefore also corresponds to the embossing structure of the nonwoven material 1 in the top view. It is evident that, in the top view, the impressions 2 are shaped in the form of wavy sections corresponding to the raised areas 8 of the roller. The surface portion of the impressions is typically between 5% and 20%.

(15) The continuous fibers 3 as well as the staple fibers 4 are formed of polyolefin, in particular polypropylene (PP). A polyester, in particular PET, also is a possible alternative material for the staple fibers 4.

(16) FIG. 2 shows the steps for producing the nonwoven material 1. As shown, continuous fibers 3 are first extruded from an extruder 9 and are deposited in order to produce a spun bonded fabric 10. The deposited continuous fibers 3 are guided through a roller gap 11 in an incompletely hardened state and are thereby interconnected to a slight extent.

(17) Next, a carding device 12 produces a layer 13 of carded staple fibers 4 and places the layer onto the spun bonded fabric 10 such that the staple fibers 4 are located on a first side of the thusly formed nonwoven material 1.

(18) Subsequent thereto, the nonwoven material 1, which still has two layers at this point, is fed to a roller gap 11 between two rollers 7, 7, wherein one of the rollers 7 has the embossing structure (according to FIG. 4) and a perforation having a plurality of openings 14 between the raised areas 8 of the embossing structure.

(19) A pressurized liquid is fed to the roller 7 provided with the raised areas 8 in order to produce liquid jets at the openings 14, wherein said liquid jets are referred to as water jets within the scope of the invention, even if water is not fed, but rather an aqueous liquid or another liquid. While the nonwoven material 1 is embossed in the roller gap 11 between the rollers 7, 7, the continuous fibers 3 are blended and intertwined with the staple fibers 4 by the action of water jets. As a result, a nonwoven material layer forms out of the fiber blend, which contains staple fibers 4 and continuous fibers 3 across the thickness thereof. As such, a somewhat greater concentration of the staple fibers 4 is generally expected on the first side of the nonwoven material 1, because the staple fibers were originally placed there.

(20) FIG. 2 also shows that the nonwoven material 1 is dried and then rolled up.

(21) FIG. 3 shows the further processing, wherein a carrier film 15 is supplied and is provided with a decorative impression in a printing unit 16. Subsequently, the adhesive 5 is applied onto the carrier film 15 in a pattern via a roller arrangement 17 before the carrier film 15, comprising the adhesive 5 disposed thereon in a pattern, is laminated with the nonwoven material 1, thereby ultimately resulting in the material depicted in FIG. 1.

(22) FIG. 5 shows, as an example, a suitable adhesive pattern for connecting the nonwoven material 1 with the carrier film 15. The surface portion of adhesive 5 and, therefore, also the portion of the bonded regions is preferably between 10 and 30%. The amount of adhesive 5 present, on average, over the entire surface is preferably between 1.5 g/m.sup.2 and 5 g/m.sup.2. The width of the individual webs provided with adhesive are in the range of 1 to 1.5 mm, for example.

Example 1

(23) In an embodiment, a monofilm of polyethylene having a thickness of 14 m, produced by blown film extrusion, was supplied and provided with a decorative impression on a first side. The PE monofilm formed of a mixture of PE-LLD and PE-HD was then provided with a single-component PUR adhesive having the adhesive pattern according to FIG. 5 and was provided with a nonwoven material 1 having a mass per unit area of 35 g/m.sup.2. The nonwoven material 1 is formed of continuous fibers 3 and staple fibers 4, each of which comprise polypropylene. The mass per unit area of the adhesive applied for the lamination is 3.0 g/m.sup.2.

Example 2

(24) While all other parameters remain the same, the mass per unit area of the nonwoven material was increased from 35 g/m.sup.2 to 40 g/m.sup.2.

Comparative Example

(25) The carrier film 15 having the above-described configuration was imprinted and then provided with the single-component PUR adhesive having a mass per unit area of 1.8 g/m.sup.2 having the pattern depicted in FIG. 5. A known knitted fabric made of polyamide having a mass per unit area of 18 g/m.sup.2 was laminated instead of the nonwoven material 1.

(26) TABLE-US-00001 TABLE 1 Peel Fmax [N/inch] 3M CHK 01088 - Hook 3M KN 2570- Hook Binder 445 PEEL Mean Min Max Mean Min Max Mean Min Max Example 1 1.5 0.9 2.8 3.5 1.8 4.9 7.5 5.3 11.1 Example 2 3.8 1.8 6.6 5.7 3.3 7.4 10.5 7.4 13.4 Comparative example 2.8 2.1 4.9 2.5 2.0 3.7 6.3 3.3 10.0

(27) TABLE-US-00002 TABLE 2 Shear Fmax [N/inch] 3M CHK 01088 - Hook 3M KN 2570- Hook Binder 445 SHEAR Mean Min Max Mean Min Max Mean Min Max Example 1 41.6 26.7 51.5 40.0 31.1 53.2 32.9 12.4 41.9 Example 2 39.5 21.6 62.5 45.0 33.0 50.4 39.3 24.2 61.8 Comparative example 58.8 51.6 67.7 29.1 19.8 44.4 39.1 30.9 52.9

(28) Tables 1 and 2 show the results of a peel measurement and a shear measurement of the examples.

(29) In order to prepare the samples, a strip of the nonwoven material is cropped in a transverse direction relative to the production process depicted in FIGS. 2 and 3 with a width of one inch (24.4 mm). In order to obtain a defined connection with the hooks, the sample is then hung in a hanging device. Then, a hook strip having a mass of 500 g is pressed by hand against the nonwoven material for a duration of 3 seconds and then hangs on the nonwoven material 1 under a weight load for 5 seconds before the weight is removed.

(30) The further testing is then carried out with the standard settings of a Zwick device. To do so, the nonwoven material 1 is inserted into the lower clamping jaw and the hook strip is inserted into the upper clamping jaw. In the shear measurement, the hook strip and the nonwoven material 1 are disposed flat in a plane. In a peel measurement, the nonwoven material 1 is clamped such that, proceeding from the hook strip, the material is folded onto itself by 180. In the tensile test, a peel-off by 180 is simulated.

(31) In a variation of the test parameters, it is shown that the specific properties are determined in the same manner in the relative comparison of the various materials with one another. The specific test method that is selected is therefore merely an example and is used for the purpose of explanation.

(32) The measurements show that the peel and shear values of a known texturized polyamide knitted fabric are met or even exceeded with various masses per unit area of the nonwoven material 1 according to the invention. The closure element according to the invention is characterized by a very soft, uniform and visually appealing surface.

(33) As will be evident to persons skilled in the art, the foregoing detailed description and figures are presented as examples of the invention, and that variations are contemplated that do not depart from the fair scope of the teachings and descriptions set forth in this disclosure. The foregoing is not intended to limit what has been invented, except to the extent that the following claims so limit that.