Nonwoven fabric element and method of manufacture

Abstract

The invention relates to a nonwoven element (1) for forming at least one hook engagement surface for a hook and loop fastener, comprising at least one nonwoven layer formed from a fiber pile (2) which extends in a longitudinal direction (MD) and a transverse direction (CD) and has a thickness (H) perpendicular thereto. The fiber pile (2) comprises a plurality of plastic fibers (5), wherein the nonwoven layer has a pattern of open areas (3) for the engagement of hook elements (7) of a hook and loop fastener and bonded areas (4) surrounding the open areas (3) and having a smaller thickness (D2). According to the invention, the fiber pile (2) is formed from a homogeneous fiber mixture with a first fiber component and a second fiber component. The first fiber component comprises 20 wt.% to 80 wt.% of the fibers.-% of the fiber mixture and is formed from a multi-component fiber, in particular a bi-component fiber, with a first polymer material and a polyolefinic second polymer material. The melting point of the first polymer material is higher than the melting point of the second polymer material. The fiber mixture further comprises a second fiber component consisting of a monofiber made of a polyolefinic third polymer material.

Description

[0001] The invention relates to a nonwoven fabric element for forming a hook engagement surface for a hook and loop fastener, comprising at least one nonwoven fabric layer formed from a fibrous web, which extends in a longitudinal direction (machine direction) and a transverse direction and has a thickness perpendicular thereto - also referred to as bulk.

[0002] Hook-and-loop fasteners are detachable mechanical fastening systems in which a first component, the so-called "hook band," equipped with hooks or locking elements, can be brought into engagement with a so-called "hook engagement surface." The hook engagement surface typically comprises fiber structures, particularly nonwovens or loop materials, into which the hooks or locking elements of the hook band can engage. Hook-and-loop fastener systems are therefore also referred to as "hook-and-loop fasteners." The mechanical connection is created by bringing the hook band into contact with the hook engagement surface. The hooks or locking elements come into contact with individual fibers in the hook engagement surface, forming a particularly positive locking connection.

[0003] A hook and loop fastener can usually absorb particularly large forces in a plane with the surfaces of the hook tape and the hook engagement surface (contact plane). This is also referred to as shear force. To release, the hook tape and the hook engagement surface are pulled apart perpendicular to the contact plane. Ideally, a hook and loop fastener has a lower resistance to this kind of peel force. The locking or hook connections between the hook tape and the fibers of the hook engagement surface are ideally overcome by elastic deformation of the hooks. In this case, the release process is completely reversible. However, it can also happen that individual fibers are destroyed and / or detached from the hook engagement surface when the hook tape is released. This can sometimes significantly impair the subsequent holding forces of the hook and loop fastener.

[0004] Hook-and-loop fasteners are widely used in personal hygiene products, particularly diapers and incontinence products. A key advantage of hook-and-loop fasteners is that they can be removed and reattached multiple times. Their holding properties are unaffected by any contamination from care products such as creams, baby oil, or other liquids. However, the economical use of such mass-produced products requires that material and manufacturing costs be reduced as much as possible. Since structured textiles such as loop-knitted fabrics require high production costs, nonwoven elements have increasingly been used to form the hook engagement surfaces.

[0005] Nonwovens are formed from a loose, random fiber composite—also known as a fiber web—which is then bonded together to form a nonwoven fabric through a bonding process. Various bonding methods are known, which can be based on physical-mechanical entanglement of the individual fibers and / or chemical or physical-thermal bonding of the fibers.

[0006] In contrast to structured textiles - i.e. in particular knitted, woven or woven - hook engagement surfaces made of nonwoven elements have the increased problem that individual fibers become detached when the hook and loop fastener is released. Due to the random arrangement of the fibers within a nonwoven fabric, the specific connection points between the individual fibers are always subject to statistical fluctuations. In order to prevent the fibers from pulling out in a conventional nonwoven fabric, particularly strong bonding is necessary. However, this has the disadvantage that with an increasing degree of bonding, the hooks are increasingly unable to penetrate the hook engagement surface and thus form hook connections. Particularly strong bonding also impairs the visual appearance, the haptic properties and also the air permeability or breathability.

[0007] The invention therefore relates to a nonwoven element in which the fiber web comprises a large number of plastic fibers and the nonwoven layer has (in the longitudinal and transverse directions) a pattern of open areas for engagement with hook elements of a hook and loop fastener and bonded areas surrounding the open areas and having a smaller thickness. Although the fiber web is also consolidated into a nonwoven layer in the open areas, a smaller bond between the individual fibers is sufficient there because the fibers are firmly bonded to one another in the bonded areas. This makes it easier to meet the mechanical requirements of a hook and loop fastener. In particular, at least 75% of the fibers are bonded to one another in the bonded areas. For this purpose, the nonwoven layer is compressed to a smaller thickness in the bonded areas.

[0008] The open areas, on the other hand, have a larger volume ("bulk") and are therefore more open-pored to accommodate the hook elements of the hook tape. Due to the randomly distributed orientation of the individual plastic fibers within the fiber pile, the individual fibers in most cases extend into at least one open area as well as at least one bonded area.

[0009] Such generic nonwoven elements are known from the prior art, for example, from WO 97 / 024 482 A1. Despite the patterned bonding of the nonwoven, the state of the art always moves between sufficient adhesive strength of the hook-and-loop fastener and securing the nonwoven fibers against tearing, on the one hand, and other properties of the nonwoven element. The nonwoven element should, if possible, be breathable and permeable to air, at least visually creating a pleasantly "fluffy" impression, and offering sufficient engagement surface for snap hooks. Added to this is the constant effort to reduce material and manufacturing costs and simplify the production process.

[0010] Against this background, the invention is based on the object of providing a nonwoven element for forming a hook engagement surface for a hook-and-loop fastener that is improved with respect to at least one of these properties. The subject matter of the invention is a nonwoven element according to claim 1 and a manufacturing method according to claim 22.

[0011] Based on the prior art, the invention provides that the fiber web is formed from a homogeneous fiber mixture with a first fiber component and a second fiber component. The first fiber component forms 20 wt.% to 80 wt.% of the fiber mixture and is formed from multi-component fibers, in particular bi-component fibers with a first polymer material and a polyolefinic second polymer material. The melting point of the first polymer material is higher than the melting point of the second polymer material. Furthermore, the fiber mixture has a second fiber component made of a monofiber consisting of a polyolefinic third polymer material. Multi-component fibers, in particular bi-component fibers with a high-melting and a low-melting polymer material, have advantages in processing and the properties of the end product.On the one hand, the high-melting polymer component contributes to good structural integrity of the fiber web both during processing and in the finished product. At the same time, the presence of at least one lower-melting polymer component ensures that temperatures during processing do not have to be as high as those required to at least partially melt the high-melting component. In the nonwoven element according to the invention, the thermal bonding steps are preferably based exclusively on melting or melting the low-melting polymer components. However, the consistent use of multi-component fibers is cost-intensive, since they require not only an additional starting material but also a more complex manufacturing process.To achieve the desired manufacturing costs while maintaining comparable product and processing properties, the invention proposes providing an additional polyolefinic fiber component together with the multicomponent fiber in a homogeneous fiber mixture. Surprisingly, the second fiber component also benefits from the supporting properties of the high-melting first polymer material of the first fiber component. This is sufficient to ensure a sufficiently airy thickness in the open areas. Contrary to intuition, this can also be achieved by admixing a low-melting monofiber made of the third polymer material. At the same time, the polyolefinic third polymer material contributes to particularly good bonding in the bonded areas.

[0012] The first polymer material is, in particular, a non-polyolefin plastic. The flexural rigidity of such a non-polyolefin is generally significantly higher than that of polyolefins. This results in a more voluminous fiber structure. Crimping (curling) by bending the fibers is therefore unnecessary.

[0013] According to one variant of the invention, the fiber mixture comprises at least a third fiber component with a chemical and / or physical composition that differs from the first fiber component and the second fiber component. This can, in particular, influence further properties of the nonwoven element. For example, the third fiber component can be finer (lower fiber titer) than the first fiber component and the second fiber component. This leads to reduced air permeability. The third fiber component is preferably made of a plastic material, in particular a polyolefinic one.

[0014] The multicomponent fibers, especially the bicomponent fibers of the first fiber component, can be designed as core / sheath fibers or as double fibers extruded side-by-side. Asymmetric multicomponent fiber types are also possible. In core-sheath fibers, the low-melting second polymer material is arranged on the outer side.

[0015] In particular, the multicomponent fibers are composed of 50 to 75 wt.% of the first polymer material and 25 to 50 wt.% of the second polymer material. Particularly good results can be achieved within the scope of the invention with bicomponent fibers and a blend ratio of 65% to 35%, 60% to 40%, or 50% to 50%.

[0016] According to a preferred embodiment of the invention, the fiber web is composed of 30% to 50% by weight of the first fiber component. Even a small proportion of the cost-intensive multicomponent fiber, 30%, can be sufficient to produce the desired properties in the fiber web. The use of the multicomponent fiber can thus be reduced by less than half or even less than one-third compared to pure MultiCo fiber.

[0017] The first fiber component and the second fiber component and optionally a third and further fiber components can each be formed with crimped and / or smooth fibers.

[0018] According to a preferred embodiment of the invention, the fiber mixture is formed exclusively from the first fiber component and the second fiber component. Additional additives—in particular, binders—are not required. A multi-layer structure is also unnecessary, since the desired structural properties can be achieved with a consistently uniform fiber mixture.

[0019] Preferably, the second polymer material and / or the third polymer material are selected from the group consisting of polypropylene (PP), polypropylene copolymers, polyethylene (PE), or polyethylene copolymers. PE, PP, and their copolymers are inexpensive and easy-to-process polyolefin plastics. They are characterized by easily controllable melting behavior. At the same time, they exhibit good strength and durability at room temperature.

[0020] Preferably, a recycled, i.e. reused, raw material can be used as the first, second and / or third polymer material, at least as an admixture.

[0021] In order to specifically change the material properties - for example, to improve the bond strength to the first polymer material in the multi-component fiber - blends of the aforementioned substances, in particular mixtures of polyethylene and its copolymers or polypropylene and its copolymers, can also be provided as the second and / or third polymer material.

[0022] In general, up to 5% of additives can be incorporated into the first polymer material, the second polymer material, and / or the third polymer material. However, the polymer materials are particularly preferably in technically pure form.

[0023] According to a particularly preferred embodiment of the invention, both the second polymer material and the third polymer material are made of the same material. This improves the bonding of fibers of the first fiber component with fibers of the second fiber component. Since the polymer materials have similar chemical and physical properties, they are in a similar melt state during thermal processing and bond particularly well to one another in the at least partially melted state.

[0024] In a particularly preferred embodiment, the second polymer material and the third polymer material have the same main component. In particular, the formulations of the second polymer material and the third polymer material are largely identical in terms of the basic chemical chain structure—except for admixtures amounting to no more than 10 wt.%. The second polymer material and the third polymer material may differ with regard to the polymerization process, the degree of branching, the proportion of metallocene polyolefins, and / or the density. However, they are particularly preferably identical.

[0025] Regardless of the specific material selection, it is particularly preferred that the melting point of the second polymer material and the melting point of the third polymer material have a difference of no more than 5 K. As a result, the second polymer material in the first fiber component and the third polymer material in the second fiber component can be melted to a similar extent by a certain temperature during processing.

[0026] To ensure easy processing – including during fiber formation – the second polymer material and the third polymer material have a melt flow index (MFI) of at least 20 g / 10 min, preferably at least 25 g / 10 min and less than 500 g / 10 min, in particular less than 100 g / 10 min. This ensures sufficient fluidity during fiber formation. At the same time, the second polymer material and the third polymer material can be partially melted during thermal bonding by targeted temperature control in such a way that adhesive properties develop without the fibers or fiber components losing their structure.

[0027] The MFI is determined, in particular according to ISO 1133, preferably with a test temperature selected depending on the material (190°C in particular for PE, 230°C in particular for PP, 280°C in particular for PET) and test weight (2.16 kg).

[0028] Particularly preferably, the first polymer material comprises polyethylene terephthalate (PET) as its main component. In particular, the first polymer material is formed entirely from polyethylene terephthalate. This polyester exhibits high mechanical stability and, particularly in combination with polyolefins, can be combined to form multicomponent fibers.

[0029] A particularly preferred material within the scope of the invention is a polyethylene terephthalate / polypropylene bicomponent fiber combined with a polypropylene monofiber. Polypropylene exhibits greater mechanical stability than polyethylene. At the same time, the melting point difference is large enough to allow targeted melting of the polypropylene components during processing while maintaining unchanged PET content.

[0030] Another inventive aspect of the present development, independent of the specific material selection, concerns the design of the bonded fiber pile in the open areas. This additional, second aspect of the invention addresses the problem that hook engagement surfaces made of nonwoven fabric often only provide insufficient adhesive force, particularly against shear stresses. Within the scope of the additional aspect of the invention, this is overcome by the appropriate selection of the fiber pile properties.

[0031] The additional aspect of the invention is based on a nonwoven element according to the preamble of claim 1. In particular, this aspect develops a nonwoven element as described above. According to the additional aspect of the invention, the fiber web in the open areas has a fiber density between 1 × 10 10< (ten billion) fibers / m 3< and 1.5 × 10 10< (15 billion) fibers / m 3<. Particularly preferably, the fiber density is between 11 and 13 billion fibers (1.1 to 1.3 × 10 10< ) per cubic meter. The second aspect of the invention is based on the finding that precisely this parameter is of significant significance for the adhesive properties of hook elements of a hook tape in the nonwoven element according to the invention.

[0032] The fiber volume density (ρ fiber , number of fibers per cubic meter) is determined by relating the number (N fiber ) of fibers to a reference volume (V) - base area (A) times height (h). ρ Faser = N Faser V = N Faser A ⋅ h

[0033] The fiber number is calculated from the ratio of the total fiber length (L) to the (average) individual fiber length (I fiber ), whereby the total fiber length (L) is calculated as the average value of the ratios of the basis weight (ρ A ) of the nonwoven element to the fiber titres (Tt i ) of the individual fiber components, weighted according to their weight fractions (ci ): N Faser = L l Faser = A ⋅ ρ A l Faser ∑ i c i Tt i

[0034] The height (h) of the volume under consideration can be influenced by the roller spacing during the manufacturing process. The intended bulk height is: h Bulk = ρ A g m 2 ρ Faser 1 m 3 ⋅ l Faser 1 mm ∑ i c i % Tt i g 10.000 m

[0035] Based on the other general conditions, the fiber density according to the invention can be adjusted as desired.

[0036] Nonwovens and nonwoven products are typically characterized primarily by their areal weight—that is, the mass present per unit area. However, this parameter alone is an unsuitable measure for assessing the quality of a hook-engaging surface in terms of its mechanical holding capacity. The areal weight alone cannot provide any information about how the existing mass is spatially distributed. This parameter is also not related to the length of the individual fibers, which is significant for their integration (via the bonded areas).

[0037] The second inventive aspect is based on the finding that the key parameter for hook engagement is the fiber density of individual nonwoven fibers per unit volume. It has been shown that comparable holding forces can be achieved at the same fiber volume densities by varying the other parameters. For example, in an existing process, the basis weight, fiber length, and fiber fineness can be predetermined based on external boundary conditions. The invention then teaches adjusting the thickness of the open areas (bulk) such that the nonwoven element has a fiber volume density within the range according to the invention. Tests by the applicant have shown that in this parameter range - with variable other parameters - a particularly good hook engagement force can be achieved.

[0038] This works particularly well when the fiber pile has an average fineness (titer) of 1 dtex to 8 dtex, especially 1.3 dtex to 6.7 dtex. Finenesses greater than 2 dtex, especially 2.2 dtex to 6.7 dtex, can be used if good air permeability and breathability are to be ensured. A certain degree of air permeability is also required if the material is to be held in place by negative pressure during the manufacturing process. If the nonwoven element is also required to regulate air and / or water vapor transport, a lower fiber titer between 1.3 dtex and 1.9 dtex must be used.

[0039] The nonwoven element preferably has a basis weight between 30 and 60 g / m², in particular between 35 and 45 g / m² (grams per square meter, gsm). Sufficient mechanical stability and adhesive strength can already be provided within this range.

[0040] The fiber pile preferably has average fiber lengths between 35 mm and 75 mm, in particular between 38 mm and 72 mm. Due to the fine structures, an average fiber length of preferably between 40 mm and 50 mm is recommended for good processability.

[0041] The fibers of the fiber blend—in particular the first fiber component and / or the second fiber component—can preferably have a non-circular cross-section—in particular a trilobal cross-section. This allows the desired fiber bulk density to be achieved due to higher stiffness at the same linear density (dtex) and lower basis weight.

[0042] Further inventive aspects of the development concern the pattern formed by the open areas and the bonded areas. These, in particular, have an ellipsoidal shape.

[0043] Based on one of the preceding claims or the preamble of claim 1, a third inventive aspect provides that the open regions at least partially have a regular pattern consisting of its first shape and a second shape, wherein the first shape has a larger area than the second shape. Both the first shape and the second shape are convex. Due to the convex shape, a particularly large number of fibers within the area can extend into an immediately adjacent bonded region and thus be fixed. This improves the integration of the individual fibers into the nonwoven element. The pulling out of individual fibers when the hook and loop fastener is released can thus be reduced.

[0044] According to a first variant, the first shape and the second shape are formed exclusively from open areas without bonded zones arranged therein. According to an alternative variant, a bonding line is arranged within the first shape and / or within the second shape, extending circumferentially parallel to the edge of the respective shape.

[0045] To achieve the greatest possible surface utilization with numerous open areas, the first shape and the second shape differ in size. Preferably, the first shape is at least twice as large as the second shape. Particularly preferably, the first shape is approximately five times the size of the second shape. In a particularly preferred embodiment, the second surface is approximately 1 / 10 of the first shape.

[0046] To maintain a uniform appearance, the first and second shapes are preferably geometrically similar. This also allows for a shape optimized for fiber adhesion in both cases.

[0047] Particularly preferably, the first shapes are arranged in a grid along a first direction, in particular approximately the longitudinal direction, and in a second direction—preferably perpendicular thereto—in particular approximately the transverse direction. In this arrangement, the first shapes overlap in both the first and second directions. This allows for hook engagement across the entire length and width of the nonwoven element. This prevents incorrect positioning of the hooks relative to the open areas.

[0048] The inclination α between the first direction and the longitudinal direction or between the second direction and the transverse direction is preferably no more than 5°. An inclination of no more than 2°, in particular approximately 1.2°, is particularly preferred.

[0049] The grid dimension - between the centers of adjacent first shapes - is preferably between 8 mm and 9 mm, preferably about 8.5 mm, in the first direction and preferably between 9 mm and 10 mm, in particular about 9.6 mm, in the second direction.

[0050] The second (smaller) shapes are preferably arranged on the same grid between the larger first shapes. They thus essentially fill the gaps in the grid of the first shapes.

[0051] Particularly preferably, the first shapes have an elliptical shape with first major axes (largest diameter) and first minor axes (smallest diameter). The second shapes also have an elliptical shape with second major axes and second minor axes. The first major axes are aligned parallel to each other and perpendicular to the second major axes of the second shapes. This allows for particularly good parquetry of the nonwoven material with open areas. At the same time, the elliptical shape improves fiber adhesion in aligned (carded) nonwoven fibers.

[0052] The first major axes preferably have a size between 6 and 8 mm, in particular approximately 7 mm. The first minor axes preferably measure 4 to 8 mm, in particular 5 mm. The second major axes are preferably 2 to 4 mm, in particular 2.7 mm. The second minor axes preferably measure between 1 and 2 mm, in particular approximately 1.3 mm.

[0053] In a particularly preferred embodiment, the nonwoven element has a single continuous bonded region between which the first shapes and second shapes are formed as open regions.

[0054] Advantageously, adjacent first and second shapes have a minimum distance of between 0.25 mm and 0.7 mm, in particular approximately 0.4 mm. Such a narrow configuration of the bonded area between them is sufficient to provide adequate fiber integration. At the same time, the bonded areas—that is, those not involved in the hook engagement—are minimized.

[0055] Another inventive aspect of the development relates to an alternative pattern of the free regions and the bonded regions. This can in particular also be combined with the previously described features of the nonwoven element. According to this fourth aspect of the inventive concept, the bonded regions form a line pattern. The line pattern comprises a first group of parallel lines and a second group of parallel lines inclined at an angle β relative to the first group. The lines of the first group and the lines of the second group enclose a plurality of diamond-shaped cells. Furthermore, the line pattern has at least one - not fully circumferential - elliptical arc, which is arranged in a cell in such a way that the elliptical arc lies tangentially on all four lines of the first group and the second group enclosing the cell.The line pattern is formed from a multitude of different linear bonded regions. These linear bonded regions have an approximately constant width of less than 1.5 mm and, in contrast, a significantly greater longitudinal extent. In the pattern according to the fourth aspect of the invention, the open regions form cushion-shaped centers, which are bordered at least on three sides and in a C-shape by the non-closed elliptical arc. In addition, the lines of the first group and the lines of the second group form a diamond-shaped network that encompasses and stabilizes the elliptical arc-shaped line components. Furthermore, the open regions lying outside the elliptical arcs are subdivided and stabilized by the lines running within them. Due to the tangential connection of the elliptical arc, these regions adjoin the diamond pattern in a particularly space-saving and stable manner.

[0056] Particularly preferably, the lines of the first group and / or the lines of the second group are not continuous, so that the lines of the first group and the lines of the second group do not touch. In particular, the bonded region is left out in the corner regions of the diamond-shaped cells - i.e. at the intersection points of the lines of the first group and the lines of the second group - so that an open region is also present there. Thus, a grid of open regions enclosed by the bonded regions is also formed in the grid of diamond-shaped cells. The bonded line areas in this case also form a continuous pattern across the entire material web of the nonwoven element.

[0057] According to all aspects of the present invention, it is preferably provided that the bonded regions account for a surface area of ​​between 15% and 30%, in particular between 20% and 25%, of the surface of the nonwoven element. Particularly in conjunction with elliptical cushions in the open regions—whether enclosed by an elliptical arc or completely elliptical—it can be mathematically demonstrated that, starting with a surface area of ​​20%, there is a predominant probability that a large proportion of the plastic fibers are embedded in the bonded regions and thus secured against being pulled out of the nonwoven element. This achieves the optimal compromise between the largest possible open region and securing all fibers.

[0058] The scale of the sample is preferably chosen so that the fibers randomly arranged in the open areas are most likely held in bonded areas on both sides. It has been shown that separate observation in the longitudinal (machine) direction and the transverse direction is sufficient to predict the tear-out behavior and thus the adhesion properties. It is also sufficient to consider only the largest open areas.

[0059] As an estimate of the probability that a particular fiber aligned in the longitudinal or transverse direction is bound only on one side, the ratio of the extension (u) of the open area in this longitudinal or transverse direction at a given location (x) to the fiber length (I fiber ) can be considered. The probability (P bound ) of a bound fiber (at a given location) is then: P gebunden x = 1 − u x l Faser

[0060] A particularly good fiber adhesion is achieved when - both when viewed in the longitudinal direction and in the transverse direction - averaged over the entire open area, a bonding probability P bound of at least 70%, preferably at least 80%. Particularly preferred is the minimum local binding probability min x P gebunden x both in the longitudinal and transverse directions greater than 70%, in particular greater than 80%.

[0061] A further independently inventive aspect of the present development lies in the process for producing the nonwoven element. This process, in particular, allows the production of a previously described nonwoven element according to at least one of the above-described aspects of the invention. Within the scope of the inventive concept, a fiber web is first formed and subsequently thermally bonded. It is essential to the invention that both air-through bonding (ATB) and thermal calendering are used for bonding. Both bonding processes are typically in exclusive competition with each other and are used alternatively.The inventive concept is that – especially in conjunction with a previously described homogeneous fiber web made of a multi-component fiber and a low-melting monofiber – different bonding objectives are pursued and combined with one another: In air-through bonding, a heated air stream is passed through the fiber web perpendicular to the machine and cross-direction. The heated air has a temperature that leads to targeted heating of the fiber web. Within the scope of the inventive concept, the temperature is controlled such that the fibers only melt superficially and are thereby bonded to one another at random contact points between the individual plastic fibers. The geometric configuration of the fiber web existing before the air-through bonding is not changed or is only slightly changed.In particular, a loosely stacked fiber web after fiber formation retains its voluminous and airy expansion. ATB is also effective in an already patterned fiber web, particularly in the open areas. There, the airy structure is strengthened and preserved by the ATB. The second consolidation process – thermal calendering – involves rolling the fiber web with a structured and heated profile roller. As an alternative to thermal calendering, similar structuring processes, such as ultrasonic bonding, can also be used. Thermal calendering compresses the fiber web in specific areas, and the heated and partially molten fibers are pressed together in a tight space. This creates the bonded areas. These anchor the fibers of the fiber web within the nonwoven element.At the same time, they have only low air permeability and the possibility of hook elements engaging.

[0062] Air-through bonding is particularly preferably performed before thermal calendering. In the first bonding step – ATB – the fibers are loosely bonded together in the pile, so that even upon compression during the subsequent calendering, elastic recovery can occur, at least in the open areas. The targeted combination of the two bonding processes results in the nonwoven element being adapted to the technical requirements. The open areas are made voluminous and maintained by the separate air-through bonding. While they may appear "fluffy" in this state, they have a rather "hard" tactile impression. However, this is irrelevant for the intended application, as the main focus there is on the best possible mechanical properties of the hook and loop fastener.

[0063] Particularly preferably, the fiber web is carded or crimped before thermal bonding. This process aligns the fibers of the fiber web – at least partially – in the machine direction. This increases the mechanical stability of the nonwoven element and also increases the likelihood that all fibers will be securely embedded in the bonded areas.

[0064] The invention's aspects are explained below with reference to drawings that merely represent exemplary embodiments. They show schematically: Fig. 1 shows a cross section through a nonwoven fabric element according to the invention, Fig. 2 shows a plan view of a nonwoven fabric element according to the invention with a first pattern, Fig. 3 shows a plan view of a nonwoven fabric element according to the invention with a second pattern and Fig. 4 shows a schematic representation of a manufacturing method according to the invention.

[0065] The Fig. 1shows a cross-section through a nonwoven element 1 according to the invention. This has a fiber web 2 which, in accordance with the first aspect of the invention, is formed from a homogeneous fiber mixture with a first fiber component and a second fiber component. In the exemplary embodiment, the first fiber component comprises 50 wt.% of the fiber mixture and is made of a bi-component fiber with polyethylene terephthalate (PET) with a weight fraction of 60% (30% of the fiber mixture, corresponding to 3.3 dtex) as the first polymer material and polyethylene (PE) with a weight fraction of 40% (20% of the fiber mixture, corresponding to 2.2 dtex) as the second polymer material. The melting point of the polyolefinic polyethylene is below that of PET. Furthermore, the fiber mixture contains 50 wt.% (corresponding to 1.9 dtex) of a polypropylene (PP) monofiber.

[0066] The nonwoven element forms a material web extending in a longitudinal direction (machine direction, MD) and a transverse direction (CD). Perpendicular to this web plane, the nonwoven element has a thickness d 1 , d 2 (bulk) measured in a height direction H, which varies locally along the material web.

[0067] The nonwoven fabric layer has a pattern of open regions 3 with a first thickness d 1 , which are surrounded by bonded regions 4 with a smaller second thickness d 2 . In the bonded regions 4, the plastic fibers 5 of the fiber web 2 are compressed and, in the compressed state, bonded to one another by partially melting the fibers 5. Within the bonded regions 4, almost all of the fibers 5 extending therein are firmly bonded to one another by at least one connection point and are thus securely held within the fiber web 2.

[0068] Within the open areas 3, the fibers 5 are only loosely attached to one another at random intersection points 6. The connection points 6 cannot reliably prevent individual fibers 5 from being pulled out. However, they serve to maintain the structure of the open area 3, in particular to form the preset height d 1 . This height is selected such that, for a given fiber fineness, basis weight, and average fiber length, a preferred fiber bulk density of 1.2 × 10 10< fibers / m 3< is achieved in the open areas 3. The open areas 3 serve for the engagement of hook elements 7 of an associated hook tape 8, which are embedded in a carrier layer 8a. The hook tape 8, together with the nonwoven element 1, forms a hook and loop fastener, with the nonwoven element 1 forming a hook engagement surface with the open areas 3.

[0069] In the Fig. 2A plan view of a nonwoven fabric element 1 shows a first possible pattern of the open regions 3 and bonded regions 4. The open regions 3 form a regular pattern consisting of a convex first shape 9a and a convex second shape 9b. The first shape 9a has an area 10 times larger than the second shape 9b. These are geometrically similar to one another, formed as ellipses and arranged in a grid along a first direction L 1 and a second direction L 2. The first shapes 9a overlap in both the first and second directions. In the exemplary embodiment shown, there is an inclination α of 1.2° between the first direction L 1 and the longitudinal direction MD, and between the second direction L 2 and the transverse direction CD. This slight inclination can achieve production-related advantages, particularly when using profile rollers.

[0070] The first shapes 9a each have an elliptical shape with mutually parallel first main axes a 1 of approximately 7 mm and first minor axes a 2 of approximately 5 mm. The second shapes 9b also have an elliptical shape with second main axes b 1 of approximately 2.7 mm and second minor axes b 2 of approximately 1.3 mm. The main axes a 1 , b 1 of the ellipses are approximately perpendicular to one another. The grid dimension of the first shapes 9a among themselves and the second shapes 9b among themselves is (center to center) s 2 = 9.6 mm in the second direction L 2 and s 1 = 8.5 mm in the first direction L 1 . In the pattern, the bonded regions 4 make up an area share of approximately 20% and the open regions make up an area share of approximately 80%. The first shapes 9a alone account for approximately 70% of the total area. The minimum distance d between two adjacent first shapes 9a or between the first shapes 9a and adjacent second shapes 9b is approximately0.4 mm.

[0071] The Fig. 1 can be seen as a cut through Fig. 2 along the line AA.

[0072] The Fig. 3shows an alternative pattern in accordance with a further inventive aspect of the present application. The bonded regions 4 form a line pattern. The line pattern comprises a first group of parallel lines 10a and a second group of parallel lines 10b inclined by 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 that interruptions are provided at the intersection points 11, which interruptions are not formed as bonded regions, but as open regions 3. Outside of the intersection points 11, the lines of the first group and the second group 10a, 10b are continuous. The lines of the first group 10a and the lines of the second group 10b are each arranged equidistantly in such a way that they enclose diamond-shaped cells 12, the corners of which are formed by the intersection points 11.The side edges of the diamond-shaped cells 12 are each formed by uninterrupted sections of lines of the first group 10a and lines of the second group 10b.

[0073] Within each diamond-shaped cell 12, an incompletely circumferential elliptical arc 13 of the line pattern is arranged. This arc tangentially touches the line segments surrounding the cell 12. In the exemplary embodiment shown, the elliptical arc 13 is designed such that a complete quadrant is left out between the contact points of two adjacent edge segments. Within the elliptical arc 13, a cushion-shaped section 14 of an open region 3 is formed, which, due to the interruption of the lines 10a, 10b at the intersection point 11, also adjoins open regions 15 outside the elliptical arcs 13 in adjacent cells 12 without interruption. The width b of the cushion-shaped section 14 in the exemplary embodiment is approximately 12 mm. The height h of the cushion-shaped section 14 at the maximum height of the elliptical arc 13 is approximately 8 mm.

[0074] The Fig. 4shows a schematic representation of a manufacturing process according to the invention. In a first work step I, a fiber mixture, in particular a homogeneous fiber mixture of a multi-component fiber and a low-melting monofiber, is produced. The staple fibers 16 thus laid are first fed to a carding machine 17 and roughly aligned there. The carded fiber web 18 is then subjected to a first thermal bonding II by air-through bonding (ATB). In this process, the carded fiber web 18 is transferred via a suction roller 19 to a large drum 20 into which a continuous hot air stream 21 enters. The temperature of the hot air stream 21 is selected such that the fibers of the fiber web 18 melt on the surface and bond with one another at random contact points 6. The pre-bonded fiber web 23 is removed from the drum 20 via a second roller 22, which is optionally equipped with a cooling function.

[0075] The pre-consolidated fiber web 23 is then passed through the nip between two rollers 24, at least one of which is profiled, for thermal calendering III. By appropriately controlling the temperature of the rollers 24, the pre-consolidated fiber web 23 is compressed and increasingly melted, at least in some areas—in the later bonded areas 4. This creates the pattern of open areas 3 and bonded areas 4. The geometry of the embossed pattern can be determined by the patterning of the profiled rollers 24. The finished nonwoven element 1 can then be wound onto a roll 25.

Claims

1. Nonwoven fabric element (1) for forming at least one hook engagement surface for a hook and loop fastener, comprising at least one nonwoven fabric layer formed from a fibrous web (2) which extends in a longitudinal direction (MD) and a transverse direction (CD) and has a thickness (d1, d2) perpendicular thereto, wherein the fibrous web (2) comprises a plurality of plastic fibers (5), wherein the nonwoven fabric layer (1) has a pattern of open areas (3) for engagement of hook elements (7) of a hook and loop fastener and bonded areas (4) surrounding the open areas (3) and having a smaller thickness (d2), characterized in thatthe fiber pile (2) is formed from a homogeneous fiber mixture with a first fiber component and a second fiber component, that the first fiber component forms 20 wt.% to 80 wt.% of the fiber mixture and is formed from multi-component fibers, in particular bi-component fibers with a first polymer material and a polyolefinic second polymer material, that the melting point of the first polymer material is higher than the melting point of the second polymer material and that the fiber mixture has a second fiber component made of a monofiber consisting of a polyolefinic third polymer material.

2. Nonwoven element (1) according to claim 1, characterized in that the fiber mixture consists of 30 wt.% to 50 wt.% of the first fiber component.

3. Nonwoven element (1) according to claim 1 or 2, characterized in that the fiber mixture is formed exclusively from the first fiber component and the second fiber component.

4. Nonwoven element (1) according to one of claims 1 to 3, characterized in that the second polymer material and / or the third polymer material is selected from the group polypropylene (PP), polypropylene copolymers, polyethylene (PE) or polyethylene copolymers.

5. Nonwoven element (1) according to claim 4, characterized in that both the second polymer material and the third polymer material are selected from the same group.

6. Nonwoven element (1) according to one of claims 1 to 5, characterized in that the melting point of the second polymer material and the melting point of the third polymer material have a difference of not more than 5 K.

7. Nonwoven element (1) according to one of claims 1 to 6, characterized in that the second polymer material and the third polymer material have a melt flow index (MFI) between 20 g / 10 min and 500 g / 10 min.

8. Nonwoven element (1) according to one of claims 1 to 7, characterized in thatthe first polymer material is made of polyethylene terephthalate (PET).

9. Nonwoven element (1) according to one of claims 1 to 8, characterized in that the fiber pile (2) in the open areas (3) has a fiber density between 1.0 × 10 10 Fibers / m 3 and 1.5 × 10 10 Fibers / m 3 , especially between 1.1 × 10 10 Fibers / m 3 and 1.3 × 10 10 Fibers / m 3 , has.

10. Nonwoven element (1) according to one of claims 1 to 9, characterized in that the fibers of the first fiber component and / or the fibers of the second fiber component have a non-round, in particular trilobal, cross-section.

11. Nonwoven element (1) according to one of claims 1 to 10, characterized in that the fiber pile (2) has an average fineness (titer) of 1 dtex to 8 dtex, in particular 1.3 dtex to 6.7 dtex.

12. Nonwoven element (1) according to one of claims 1 to 11, characterized in thatthe nonwoven element (1) has a basis weight between 30 and 60 g / m 2 , especially 40 to 50 g / m 2 has.

13. Nonwoven element (1) according to one of claims 1 to 12, characterized in that the open areas (3) at least partially have a regular pattern of a convex first shape (9a) and a convex second shape (9b), wherein the first shape (9a) has a larger area than the second shape (9b) 14. Nonwoven element (1) according to claim 13, characterized in that the first shape (9a) and the second shape (9b) are geometrically similar.

15. Nonwoven element (1) according to one of claims 13 or 14, characterized in that the first shapes (9a) are arranged in a grid along a first direction, in particular the longitudinal direction, and a second direction, in particular the transverse direction, and that the first shapes (9a) overlap in both the first direction and the second direction.

16. Nonwoven element (1) according to one of claims 13 to 15, characterized in that the first shapes (9a) have an elliptical shape with, in particular, first main axes (a1) and first secondary axes (a2) arranged parallel to one another, that the second shapes (9b) have an elliptical shape with, in particular, second main axes (b1) and second secondary axes (b2) arranged parallel to one another, and that the first main axes (a1) are aligned parallel to one another and each approximately perpendicular to the second main axes (b1).

17. Nonwoven element (1) according to one of claims 13 to 16, characterized in that the bonded region (4) is formed continuously / continuously between the first shapes (9a) and the second shapes (9b).

18. Nonwoven element (1) according to one of claims 13 to 17, characterized in that the adjacent first surfaces and second surfaces have a minimum distance between 0.25 mm and 0.7 mm, in particular 0.4 mm.

19. Nonwoven element (1) according to one of claims 1 to 12, characterized in that the bonded regions (4) form a line pattern, such that the line pattern has a first group of parallel lines (10a) and a second group of parallel lines (10b) inclined by an angle (β) with respect to the first group, such that the lines of the first group (10a) and the lines of the second group (10b) enclose a plurality of diamond-shaped cells (12), and such that the line pattern has at least one elliptical arc (13) which does not fully encircle the cell and is arranged in such a way that the elliptical arc (13) lies tangentially against all four lines of the first group (10a) and the second group (10b) enclosing the cell.

20. Nonwoven element (1) according to claim 19, characterized in thatthe lines of the first group (10a) and / or the lines of the second group (10b) are not continuous and that the lines of the first group (10a) and the second group (10b) do not touch.

21. Nonwoven element (1) according to claim 19 or 20, characterized in that in each of the diamond-shaped cells (12) a not fully circumferential elliptical arc (13) is arranged tangentially.

22. Nonwoven element (1) according to one of claims 1 to 21, characterized in that the bonded areas (4) make up between 15% and 30%, in particular between 20% and 25% of the area of ​​the nonwoven element (1).

23. A method for producing a nonwoven element (1), in particular according to one of claims 1 to 22, wherein first a fiber web (2) is formed and subsequently thermally bonded, characterized in that For consolidation, both air-through bonding (ATB, II) and thermal calendering (III) are used.

24. Method according to claim 23, characterized in that the air-through bonding (II) is carried out before thermal calendering (III).

25. Method according to claim 23 or 24, characterized in that the fiber web (2) is carded or rolled before thermal bonding.

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