US20250297415A1

US20250297415A1 - Method and apparatus for making a nonwoven textile

Info

Publication number: US20250297415A1
Application number: US18/859,414
Authority: US
Inventors: Sebastian Sommer; Patrick Bohl; Andreas ROESNER; Tobias Wagner
Original assignee: Reifenhaeuser GmbH and Co KG Maschinenenfabrik
Current assignee: Reifenhaeuser GmbH and Co KG Maschinenenfabrik
Priority date: 2022-06-17
Filing date: 2023-06-16
Publication date: 2025-09-25
Also published as: WO2023242406A1; CA3253084A1; JP2025519437A; MX2024015707A; KR20250025431A; CO2024016909A2; DE102022115205A1; EP4540449A1; IL316982A; CL2024003724A1; PE20251561A1; CN119384529A

Abstract

The invention relates to a method for producing a nonwoven fabric comprising at least one nonwoven web composed of fibres. The fibres are produced by means of at least one fibre-producing device. Subsequently, the fibres are deposited on at least one depositing device in order to form the nonwoven web. The nonwoven web or nonwoven fabric is solidified with at least one calender roller, and the nonwoven fabric is also solidified or primarily solidified with at least one hot fluid primary solidification device.

Description

The invention relates to a method of making a nonwoven fabric comprising at least one nonwoven web of filaments, wherein filaments are made using at least one filament-making device, in particular using at least one spinning beam, wherein the filaments are subsequently deposited on at least one receiving device, in particular on a foraminous belt, to form the nonwoven web. The invention also relates to an apparatus for making a nonwoven fabric.
Methods and apparatuses for making nonwovens are basically known from practice in different embodiments. The filaments made are usually deposited on a receiving device to form the nonwoven web and then preconsolidated to ensure the transportability of the nonwoven web or nonwoven fabric and to ensure that the nonwoven web is not displaced or destroyed during transport through the apparatus. For further consolidation or main consolidation, the nonwoven fabric is usually fed to a following apparatus. As following apparatuses for consolidation or main consolidation of nonwoven fabrics, calenders comprising at least one calender roller, in particular comprising at least one pair of calender rollers, are known. Calender rollers with embossing elements are frequently used that introduce an embossing pattern comprising a large number of embossments into the nonwoven fabric during the consolidation process. Although nonwoven fabrics that have been created with at least one calender are characterized by advantageous mechanical strength, these nonwoven fabrics frequently have a low thickness or low volume. In addition, the embossing patterns introduced into the nonwovens using a calender are advantageous or necessary with regard to the mechanical properties of the nonwoven fabrics, but are disadvantageous for aesthetic reasons, since the visual properties of the nonwoven fabric may thereby be adversely affected. Known from practice, therefore, as alternatives to consolidation or main consolidation of nonwoven fabrics are additionally hot-fluid consolidaters or hot-air consolidaters such as hot-air ovens. Nonwoven fabrics that are consolidated or mainly consolidated using such consolidaters are generally characterized by an advantageous thickness or voluminosity, but frequently have an undesirable stiffness or are difficult to drape and in some cases have a disadvantageously low abrasion resistance.
An acceptable compromise between a sufficient mechanical strength, a satisfactory thickness or voluminosity, a low stiffness or a satisfactory drapability and a sufficient abrasion resistance has so far been achieved at best by mixing different filament types in nonwoven fabrics. However, this is complex and the corresponding processes are also not very flexible to use.
In view of this, the object of the invention is to provide a method of the above-mentioned type in which the above-described disadvantages can be effectively and reliably avoided and with which, in particular, a nonwoven fabric can be made that is characterized by advantageous mechanical properties, for example by a sufficient mechanical strength or surface resistance, by a sufficient thickness or voluminosity, by a low stiffness or satisfactory drapability and preferably by an improved abrasion resistance, whereby an optimal compromise between these nonwoven fabric properties is particularly desirable. Furthermore, the invention has the object of providing a corresponding apparatus for making a nonwoven fabric, as well as such a nonwoven fabric.
To attain these objects, the invention teaches a method of making a nonwoven fabric comprising at least one nonwoven web of filaments, wherein filaments are made using at least one filament-making device, in particular using at least one spinning beam, wherein the filaments are subsequently deposited on at least one receiving device, in particular on a foraminous belt, to form the nonwoven web, wherein the nonwoven web or the nonwoven fabric is consolidated with at least one calender roller, in particular with at least one calender or calender roller pair comprising the calender roller, and wherein the nonwoven fabric is additionally consolidated or main consolidated with at least one hot-fluid main consolidater, in particular with at least one hot-air main consolidater.
The fact that the nonwoven fabric comprises at least one nonwoven web of filaments means in particular within the scope of the invention that the nonwoven fabric comprises at least one nonwoven web or nonwoven layer composed of made and deposited filaments. According to one embodiment, the nonwoven fabric can comprise only one nonwoven web or one nonwoven layer, or it can comprise several nonwoven webs or nonwoven layers one above the other that are combined to form the nonwoven laminate.
In the context of the invention, the term “consolidation” or “main consolidation” means in particular a consolidation of the nonwoven fabric that leads to a higher degree of consolidation of the nonwoven fabric than a preconsolidation. It is within the scope of the invention that with a main consolidation a lower or a higher degree of consolidation of the nonwoven fabric is achieved than with a consolidation or that with a main consolidation a degree of consolidation of the nonwoven fabric is achieved that is identical or substantially identical to that achieved with a consolidation.
According to a preferred embodiment of the invention, the nonwoven fabric is made as a spunbonded nonwoven fabric with at least one spunbonded nonwoven web or with at least one spunbonded nonwoven layer. It is possible that the nonwoven fabric is made as a nonwoven laminate from at least two spunbonded nonwoven webs or at least two spunbonded nonwoven layers. However, it is also possible that the nonwoven fabric or nonwoven laminate comprises at least one meltblown nonwoven web or meltblown nonwoven layer. It is further within the scope of the method according to the invention that the nonwoven fabric is made as a nonwoven laminate comprising at least three, for example at least four, nonwoven webs or nonwoven fabric layers. The individual nonwoven webs or nonwoven layers can each be deposited as spunbonded nonwoven webs or nonwoven fabric layers. In principle, the nonwoven laminate could also be made with at least one meltblown nonwoven web or meltblown nonwoven fabric layer. The spunbonded nonwoven webs or the spunbonded nonwoven layers are preferably each deposited from continuous filaments or crimped continuous filaments. This is explained in more detail below.
In the context of the invention, the term “hot fluid” means a temperature-controlled or heated fluid. The hot fluid is preferably a temperature-controlled or heated gas and particularly preferably hot air. In principle, the hot fluid can also be a temperature-controlled or heated liquid, for example water.
A particularly preferred embodiment of the method according to the invention is characterized in that the nonwoven fabric is detached from the receiving device before being consolidated with the at least one calender roller and/or before consolidation or main consolidation with the at least one hot-fluid main consolidater. Particularly preferably, the consolidation with the at least one calender roller or with the at least one calender comprising the calender roller and also the consolidation or main consolidation with the at least one hot-fluid main consolidater is carried out after the detachment of the nonwoven fabric from the receiving device. For this purpose, the nonwoven fabric is expediently transferred to the calender roller or calender or to the hot-fluid main consolidater after being detached from the receiving device. In principle, it is also possible within the scope of the invention that the consolidation or main consolidation with the at least one hot-air main consolidater takes place on or above the foraminous belt and that preferably only then is the nonwoven fabric detached from the receiving device.
It has proven particularly useful within the scope of the method according to the invention that the consolidation of the nonwoven fabric with the at least one calender roller, in particular with at least one calender or calender roller pair comprising the at least one calender, is carried out before or after consolidation or main consolidation of the nonwoven fabric with the at least one hot-fluid main consolidater, in particular with the at least one hot-air main consolidater. Quite particularly preferably, the nonwoven fabric, in particular after detachment from the receiving device, is first consolidated with the at least one calender roller, in particular with at least one calender or calender roller pair comprising the calender roller, and then consolidated or main-consolidated with the at least one hot-fluid main consolidater, in particular with the at least one hot-air main consolidater. This sequence of consolidation steps has proven particularly useful within the scope of the invention and for solving the technical problem.
It is recommended that after deposition on the receiving device and before consolidation or main consolidation, the nonwoven is first preconsolidated with at least one preconsolidater, preferably located downstream, in particular located directly downstream of the at least one filament-making device or the at least one spinning beam, preferably with at least one hot-fluid preconsolidater, preferably with at least one hot-air preconsolidater. The preconsolidation thus takes place in particular before a consolidation with the at least one calender roller or with the at least one calender and before a consolidation or main consolidation with at least one hot-fluid main consolidater. The preconsolidation step ensures in particular the transportability of the deposited nonwoven web or nonwoven fabric and, according to a preferred embodiment, also the detachability of the nonwoven fabric from the receiving device, as well as the functionally reliable transfer to one of the devices provided according to the invention for consolidating the nonwoven fabric. If, according to a preferred embodiment of the method according to the invention, a nonwoven fabric comprising at least two nonwoven webs of filaments is made, it is preferred that after the deposition of each nonwoven web, a preconsolidation is carried out using a preconsolidater or hot-fluid preconsolidater that is expediently located downstream of the associated filament-making device or the associated spinning beam, in particular is located directly downstream.
It is within the scope of the method according to the invention that the at least one hot-fluid preconsolidater or hot-air preconsolidater, is a hot-air knife and/or as a hot-air field. In principle, the preconsolidater can also comprise at least one roller or one smooth roller, in particular a pair of rollers or pair of smooth rollers. If the nonwoven fabric according to one embodiment is made with only one nonwoven web, it is preferred that a hot-air knife is used as the preconsolidater. If the nonwoven fabric according to the preferred embodiment is made with several nonwoven webs or nonwoven fabric layers, a hot-air knife is used as preconsolidater for the uppermost or last deposited nonwoven web or nonwoven fabric layer and in particular a hot-air knife and a hot-air field are used as preconsolidaters for the remaining nonwoven webs or nonwoven fabric layers. In the latter case, residence times for the hot-air exposure of more than 0.1 s have proven particularly effective.
It has proven particularly useful within the scope of the invention that the at least one hot-fluid main consolidater or the at least one hot-air main consolidater is a hot-air oven, particularly preferably as an omega oven and/or as a multidrum oven and/or as a single-belt oven and/or as a double-belt oven. Expediently the consolidation or main consolidation is carried out with the at least one hot-fluid main consolidater by applying at least one hot-fluid to the nonwoven fabric on one side or both sides in the at least one hot-fluid main consolidater.
It has also proven particularly useful within the scope of the invention that the at least one hot-fluid main consolidater or the at least one hot-air main consolidater is a hot-air oven, particularly preferably as a hot-air field and/or as a multidrum oven and/or as a single-belt oven and/or as a double-belt oven. According to one embodiment of the invention, the consolidation or main consolidation with the at least one hot-fluid main consolidater is carried out by applying at least one hot-fluid to the nonwoven fabric on one or both sides in the at least one hot-fluid main consolidater and in particular before the detachment from the receiving device, wherein the nonwoven fabric preferably subsequently, after detachment, is consolidated with the at least one calender roller, in particular with at least one calender or calender roller pair comprising the calender roller. It is also within the scope of the invention that at least two hot-fluid main consolidaters are provided, wherein then preferably a first consolidation or main consolidation of the nonwoven fabric is carried out with a first hot-fluid main consolidater before the detachment of the nonwoven fabric from the receiving device and wherein preferably a second or further consolidation or main consolidation with a second hot-fluid main consolidater is carried out after the detachment of the nonwoven fabric from the receiving device and particularly preferably after consolidation with the at least one calender roller, in particular with at least one calender or calender roller pair comprising the calender roller. In this embodiment, the at least one calender roller is thus preferably in the travel direction F of the nonwoven fabric between two hot-fluid main consolidaters.
According to a particularly preferred embodiment of the method according to the invention, the residence time of the nonwoven fabric in the hot-fluid main consolidater is 0.4 s to 25 s, preferably 1 s to 15 s and/or the fluid velocity of the fluid of the hot-fluid main consolidater is 0.4 to 3 m/s, preferably 0.5 to 2 m/s.
It is within the scope of the invention that the surface temperature T1 of the at least one calender roller, in particular of the at least one calender or calender roller pair comprising the calender roller is higher, preferably by 0.5° C. to 10° C., preferably by 1° C. to 5° C. higher, than the fluid temperature T2 of the at least one hot-fluid main consolidater or lower than the fluid temperature T2 of the at least one hot-fluid main consolidater or is identical or substantially identical to the fluid temperature T2 of the at least one hot-fluid main consolidater. Within the scope of the invention, the at least one calender roller, in particular the at least one calender or calender roller pair comprising the calender roller, is preferably a heated calender roller or a heated calender. Due to the temperature relationships of the surface temperature of the at least one calender roller or the calender and the fluid temperature of the at least one hot-fluid main consolidater, in particular in combination with the residence times and/or fluid velocities explained above, a method can be provided with which nonwoven fabrics can be made very flexibly that are characterized by an optimal compromise of their properties, so that the technical problem explained above can be solved very flexibly, simply and reliably.
It is fundamentally within the scope of the invention that the filaments of the at least one nonwoven web are made as short filaments or that the at least one nonwoven web contains short filaments. According to a preferred embodiment, the filaments of the at least one nonwoven web are made as continuous filaments. Particularly preferably, the filaments of all the nonwoven webs are made as continuous filaments in the process according to the invention. In this case, “filaments” in the context of the invention means in particular continuous filaments. Continuous filaments differ due to their virtually endless length from short filaments that have significantly shorter lengths of for example 1 mm to 60 mm.
A particularly preferred embodiment of the method according to the invention is characterized in that the filaments of the at least one nonwoven web are made or spun as continuous filaments. Preferably the filaments of the at least one nonwoven web or at least one nonwoven web of the nonwoven fabric are made as continuous filaments from at least one thermoplastic material, preferably from at least one polyolefin. The recommended polyolefin is at least polypropylene and/or polyethylene. In principle, the continuous filaments can also be made from other thermoplastic materials such as polyesters, for example polyethylene terephthalate (PET) and/or polylactide (PLA), as well as from mixtures of the aforesaid thermoplastic materials. According to one embodiment, copolymers of the aforesaid thermoplastic materials are used. Common additives such as plasticizers, fillers, dyes and the like can be added to the said thermoplastic materials. It is within the scope of the invention that the continuous filaments of the at least one nonwoven web or at least one nonwoven web of the nonwoven fabric are made as spunbonded continuous filaments. In principle, it is also possible that the continuous filaments of at least one nonwoven web or nonwoven web of the nonwoven fabric are made as meltblown continuous filaments.
According to a particularly preferred embodiment of the method according to the invention, the filaments of the at least one nonwoven web are made or spun as crimped continuous filaments, wherein the continuous filaments or the crimped continuous filaments are particularly preferably made or spun as multicomponent filaments and quite particularly preferably as bicomponent filaments.
In this context, it has proven particularly useful that the multicomponent filaments or bicomponent filaments have a first, preferably low-melting, component that consists of or substantially consists of at least one thermoplastic material, in particular of at least one polyolefin, preferably polyethylene and/or polypropylene, and/or that the multicomponent filaments or bicomponent filaments have a second or further, preferably higher-melting, component that consists or substantially consists of at least one thermoplastic material, in particular of at least one polyester and/or polypropylene. The term “low-melting component” in particular “first low-melting component” in the context of the invention means in particular a component of the multicomponent filaments or bicomponent filaments that has a lower melting temperature than a higher-melting component compared to this, in particular the second or further higher-melting component of the multicomponent filaments or bicomponent filaments. The low-melting component or the first low-melting component of the multicomponent filaments or bicomponent filaments in the context of the invention, is in particular a binder component for the multicomponent filaments or bicomponent filaments.
In the context of the invention, polyethylene terephthalate (PET) and/or polylactide (PLA) are particularly suitable as polyesters. According to one embodiment, copolymers of these plastics are used. When it is stated here or hereinafter that “substantially consists of” with reference to the components of the multicomponent filaments or the bicomponent filaments and in particular to a plastic or a polymer, this means in particular that the component or the polymer is provided to an extent of at least 95% by weight, preferably to an extent of at least 97% by weight and preferably to an extent of at least 98% by weight. The remaining percentage by weight can be formed in particular by additives such as plasticizers, fillers, dyes and the like.
According to a particularly preferred embodiment of the invention, the first, preferably low-melting, component of the multicomponent filaments or the bicomponent filaments is based on polyethylene and preferably consists of polyethylene or substantially of polyethylene. According to a further preferred embodiment, the first, preferably low-melting, component of the multicomponent filaments or bicomponent filaments is based on of polypropylene and preferably consists of polypropylene or substantially of polypropylene. Instead of polypropylene or in addition to polypropylene, at least one polypropylene copolymer can also be used within the scope of the invention.
The second or further, in particular higher-melting, component of the multicomponent filaments or bicomponent filaments according to a preferred embodiment of the invention, is formed on the basis of at least one polyester and/or on the basis of polypropylene. Particularly preferably, the second or further, in particular higher-melting, component of the multicomponent filaments or bicomponent filaments consists of at least one polyester and/or polypropylene. For the second or further component, at least one polypropylene copolymer can be used instead of polypropylene or in addition to polypropylene and preferably at least one polyester copolymer can be used instead of the polyester or in addition to the polyester. Expediently polyethylene terephthalate (PET) and/or polylactide (PLA) are particularly suitable as polyesters, and a PET copolymer (co-PET) is particularly suitable as polyester copolymer. It is also within the scope of the invention that a polylactide copolymer (Co-PLA) is used as the first, in particular low-melting, component and polylactide (PLA) is used as the second or further, in particular higher-melting, component.
It is within the scope of the process according to the invention that the continuous filaments, preferably the crimped continuous filaments, are made or spun as multicomponent filaments or bicomponent filaments with side-by-side configuration and/or with core-sheath configuration, in particular with eccentric core-sheath configuration and wherein preferably the first, preferably low-melting, component is the sheath component and the second, preferably higher-melting, component is the core component. If the continuous filaments are made or spun as multicomponent filaments or bicomponent filaments with core-sheath configuration, it is fundamentally also possible within the scope of the invention that this comprises a centric core-sheath configuration.
If the continuous filaments or the crimped continuous filaments according to the preferred embodiment are made or spun as multicomponent filaments or bicomponent filaments with an eccentric core-sheath configuration, it is within the scope of the invention that both the sheath of the filaments and the core of the filaments seen in the filament cross-section are configured to be circular. According to a further preferred embodiment of the invention, the multicomponent filaments or bicomponent filaments are made or spun as multicomponent filaments or bicomponent filaments with an eccentric core-sheath configuration and the core of these filaments is seen in the filament cross-section shaped like a segment of a circle and has a circular arc-shaped circumferential section and a linear circumferential section with respect to its circumference, so that a D-shape of the core, seen in the filament cross-section, results.
If the continuous filaments or the crimped continuous filaments are made or spun as multicomponent filaments or bicomponent filaments within the scope of the method according to the invention, comprising at least one previously described first, preferably low-melting, component and at least one previously described second or further, preferably higher-melting, component, the proportion of the first, preferably low-melting, component of the multicomponent filaments or bicomponent filaments in the at least one nonwoven web of the nonwoven fabric is 10 to 90 wt. %, preferably 20 to 70 wt. %, more preferably 30 to 50 wt. %, relative to the components of the multicomponent filaments or bicomponent filaments.
The configuration of the filaments of the nonwoven fabric as multicomponent filaments or bicomponent filaments, in particular with a first, preferably low-melting component and a second or further, preferably higher-melting, component and furthermore the preferred embodiment of the multicomponent filaments or bicomponent filaments with a side-by-side configuration and/or core-sheath configuration, preferably with an eccentric core-sheath configuration, are based on the discovery that as a result of these components or configurations of the filaments the nonwoven fabric properties can be adjusted very flexibly and that, in particular in combination with the consolidation provided according to the invention with at least one calender roller and with at least one hot-fluid main consolidater, a nonwoven fabric can be made with which a particularly advantageous compromise of the nonwoven fabric properties can be achieved to attain this object according to the invention.
In this context, it has proven particularly useful that the surface temperature T1 of at least one calender roller, in particular of the at least one calender or calender roller pair comprising the calender roller and/or the fluid temperature T2 of the at least one hot-fluid main consolidater in relation to the melting temperature Tm of the first, preferably low-melting, component of the multicomponent filaments or bicomponent filaments satisfies the following condition: (Tm−15° C.)<T1 and/or T2<(Tm+15° C.), preferably (Tm−10° C.)<T1 and/or T2<(Tm+10° C.), preferably (Tm−8° C.)<T1 and/or T2<(Tm+8° C.), particularly preferably (Tm−7° C.)<T1 and/or T2<(Tm+7° C.), quite particularly preferably (Tm−6° C.)<T1 and/or T2<(Tm+6° C.), for example (Tm−5° C.)<T1 and/or T2<(Tm+5° C.). In the context of the process according to the invention, the melting temperature Tm of the first, preferably low-melting, component is determined in particular by dynamic differential scanning calorimetry (DSC) according to ISO 11357-3:2011. Thus, the surface temperature T1 of the at least one calender roller and/or the fluid temperature T2 of the at least one hot-fluid main consolidater preferably satisfies the above-mentioned condition. The surface temperature T1 can preferably have the relationship to the fluid temperature T2 described above, so that T1 can preferably be higher than T2 or lower than T2 or identical to T2. If the hot-fluid main consolidater, in particular the hot-air main consolidater according to a preferred embodiment, is a hot-air oven, then the fluid temperature corresponds in particular within the scope of the invention to the temperature of the hot air during this hot-air consolidation in the hot-air oven.
According to a very preferred embodiment of the method according to the invention, an embossing pattern consisting of a plurality of preferably not interconnected embossments is introduced into the nonwoven fabric by the at least one calender roller. It is within the scope of the invention that the calender roller is part of a calender that, according to a particularly preferred embodiment, has at least one pair of calender rollers and at least one, in particular one of the two calender rollers of the calender or the pair of calender rollers is preferably a calender roller for introducing an embossing pattern comprising a plurality of embossments into the nonwoven fabric. For this purpose, the calender roller preferably has a complementary embossing pattern of embossing elements. This will be explained in more detail below. The other or further roller of the calender or calender roller pair is expediently a smooth roller with a smooth outer surface. In the context of the method according to the invention, the nonwoven fabric is thus preferably consolidated with a calender that has at least one calender roller for introducing an embossing pattern comprising a plurality of embossments into the nonwoven fabric and more preferably at least one smooth roller. Then the embossing pattern is preferably introduced into the nonwoven fabric from only one side of the nonwoven fabric. Preferably, however, the embossing pattern is nevertheless present in the resulting nonwoven fabric on both nonwoven fabric sides, with the embossing depth being distributed differently on the two nonwoven fabric sides. It is within the scope of the invention that when using a calender comprising at least one pair of calender rollers, wherein one of the calender rollers has embossing elements for introducing an embossing pattern comprising a plurality of embossments into the nonwoven fabric and one calender roller is a smooth roller, the two calender rollers have a different surface temperature from one another for consolidating the nonwoven fabric. It is preferred that the calender roller with the embossing elements has the higher surface temperature. In the case of different temperatures of the calender rollers, the surface temperature T1 described above refers in particular to the temperature of the calender roller with embossing elements.
In the context of the invention, the term “embossing” means in particular a compacted location of the nonwoven fabric where the nonwoven fabric has a smaller thickness in comparison to its nonembossed regions and where the filaments of the nonwoven fabric are at least partially connected or fused to one another, preferably by the action of pressure and/or temperature. According to a quite particularly preferred embodiment of the method according to the invention, the embossments each have an embossing area of 0.05 to 0.6 mm², preferably 0.06 to 0.4 mm², preferably 0.07 to 0.25 mm², particularly preferably 0.08 to 0.15 mm², and quite particularly preferably 0.09 to 0.12 mm². It is within the scope of the invention that the embossments each have an embossing area of less than 0.3 mm², preferably less than 0.2 mm², preferably less than 0.18 mm², particularly preferably less than 0.15 mm², very particularly preferably less than 0.12 mm², for example less than 0.1 mm². These embodiments are based on the discovery that with an embossing pattern composed of embossments of this special configuration and in particular with the relatively small embossing area, the visual perceptibility of the embossing pattern by the human eye can be at least significantly reduced, so that an impairment of the visual properties of the resulting nonwoven fabric can be almost completely avoided.
In the context of the invention, the term embossing pattern refers in particular to the pattern resulting from the plurality of embossments of the laminate or nonwoven fabric. The embossing pattern can be a regular and/or an irregular embossing pattern. Then the individual embossments are preferably distributed at regular intervals, preferably at identical intervals on the laminate. Further preferably, according to preferred embodiment of the invention, the embossing area of the individual embossments of the embossing pattern are the same size or substantially the same size. It has proven to be beneficial that the geometry of the embossing areas of the individual embossments is identical or substantially identical. Quite particularly preferably, the embossing pattern has the same or the same-size embossments or substantially the same or the same-size embossments with a homogeneous distribution of embossments of the same geometry or of substantially the same geometry. In principle, however, it is also possible that the individual embossments of the embossing pattern have a different size and/or a different geometry and/or that the embossments are in an irregular embossing pattern on the nonwoven fabric. In the context of the invention, “geometry of the embossments” means in particular the geometry of the embossing areas of the embossments in plan view.
In the context of the invention, the “embossing area” of an embossing means in particular the embossed area of an embossment, where when determining the size of the embossing area, any material overhang or material projection that may have formed in the course of the pressing or embossing process and that at least partially surrounds the embossment is in particular not part of the embossing area of an embossment. In the case of an embossment or an embossing area with a punctuate or circular geometry in plan view, the embossing area of the embossment corresponds, for example, to the area of the punctuate embossment or circular embossment, wherein the material overhang or the material projection possibly surrounding the embossment is not included in the embossing area of the embossment. The fact that the embossments of the nonwoven fabric or laminate according to the invention each have an embossing area in the above-mentioned range means in particular within the scope of the invention that at least 95%, preferably at least 97% of all the embossments of the nonwoven fabric have an embossing area in the specified range. Particularly preferably all the embossments of the nonwoven fabric have an embossing area in the specified range. Within the scope of the invention, the embossing area of an embossment can be determined in particular by incident light or transmitted light 2D microscopy, and/or by scanning electron microscopy (SEM) and/or by microcomputer tomography (CT). In the corresponding image evaluation, a geometry that forms the basis of the embossing area geometry or that corresponds or substantially corresponds to the embossing area geometry is preferably used as a basis and is placed over the individual optically imaged embossing areas of the embossments for evaluation.
It is within the scope of the method according to the invention that the embossing pattern is made such that the smallest spacing d between two embossments of the embossing pattern is 0.6 to 3.0 mm, preferably 0.8 to 2.5 mm, more preferably 0.9 to 2.0 mm, particularly preferably 0.95 to 1.8 mm and quite preferably 1.0 to 1.5 mm. Expediently, the smallest spacing d between two embossments of the embossing pattern is at least 0.6 mm, in particular at least 0.8 mm, preferably at least 1.0 mm, particularly preferably at least 1.4 mm and quite particularly preferably at least 2.0 mm. “Smallest spacing” d between two embossments of the embossing pattern means in particular the smallest spacing d between two immediately adjacent embossments of the embossing pattern, i.e. preferably the smallest spacing between one embossment and the embossment of the embossing pattern that is closest to it. Furthermore, the smallest spacing d between two embossments of the embossing pattern refers in particular to the smallest spacing between the embossing boundaries of two embossments, i.e. to the smallest spacing between the two embossments along the interposed nonembossed area of the nonwoven fabric. This embodiment is based in particular on the discovery that the visual perceptibility of the embossing pattern of embossments can thereby be further reduced. The smallest spacing between two embossments of the embossing pattern described previously preferably refers to at least 95%, preferably to at least 97% of all the embossments of the nonwoven fabric. Particularly preferably, the described smallest spacing between two embossments refers to all the embossments of the nonwoven fabric.
A further preferred embodiment of the method according to the invention is characterized in that the embossing pattern is made such that the proportion of the total embossing area of the embossing pattern to the total surface area of the nonwoven fabric is 2 to 15%, preferably 2.5 to 12%, preferably 3 to 8%, particularly preferably 3.5 to 6% and quite particularly preferably 3.8 to 5.2%. It is within the scope of the invention that the embossing pattern is made such that the proportion of the total embossing area of the embossing pattern to the total surface area of the nonwoven fabric is less than 10%, preferably less than 8%, more preferably less than 6.5%, particularly preferably less than 5.5% and quite preferably less than 5%. Due to these projecting portions of the total embossing area of the embossing pattern on the total surface area of the nonwoven fabric, the visual perceptibility of the embossing pattern of embossments can be further reduced. In this context, the “total embossing area” of the embossing pattern means in particular the sum of all embossing areas of the embossing pattern. “Total surface area” of the nonwoven fabric means in the context of the invention in particular the entire nonwoven fabric surface area including the embossed and nonembossed regions.
It is within the scope of the method according to the invention that the calender linear load of the calender roller or the calender is 4 N/mm to 60 N/mm, preferably 10 N/mm to 40 N/mm, particularly preferably 15 N/mm to 35 N/mm, quite particularly preferably 20 N/mm to 30 N/mm. More preferably, the calender linear load is 2 to 20 N/mm, preferably 3 to 15 N/mm, preferably 4 to 8 N/mm per percentage fraction of the previous described total embossing area of the embossing pattern to the total surface area of the nonwoven.
Within the scope of the method according to the invention, it is particularly preferred that a nonwoven fabric comprising at least two nonwoven webs is made from filaments, wherein for this purpose first filaments are made by at least one first filament-making device, in particular by at least one first spinning beam, and are then deposited on the receiving device, in particular on the foraminous belt, to form the nonwoven web, wherein second filaments are made by at least one second filament-making device, in particular by at least one second spinning beam, and are then deposited on the first nonwoven web to form the second nonwoven web, and wherein the laminate composed of the at least two nonwoven webs or the nonwoven fabric is consolidated with at least one calender roller, in particular with at least one calender or calender roller pair comprising the calender roller, and wherein the nonwoven fabric is additionally consolidated or main consolidated with at least one hot-fluid main consolidater, in particular with at least one hot-air main consolidater. It has already been mentioned above that, within the scope of such an embodiment, at least one preconsolidater, preferably at least one hot-fluid preconsolidater, preferably at least one hot-air preconsolidater, is expediently located downstream of each filament-making device or each spinning beam, in particular directly downstream, and that the deposited nonwoven webs are preferably each preconsolidated before a consolidation or main consolidation of the nonwoven fabric using the respective preconsolidater.
If a nonwoven fabric comprising at least two nonwoven webs composed of filaments is made within the scope of the process according to the invention, it is particularly preferred that the filaments are made as continuous filaments, in particular as crimped continuous filaments, and are each deposited as a spunbonded nonwoven web. The properties of the filaments or continuous filaments of the various nonwoven webs or nonwoven fabric layers of the resulting nonwoven fabric can vary. For example, the continuous filaments of the first nonwoven web made with a first spinning beam can have a lower average titer than the continuous filaments of the second nonwoven web made with the second spinning beam, so that a titer gradient results. It has proven to be useful that the filaments of at least one nonwoven web or nonwoven fabric layer associated with an outer surface of the nonwoven fabric are made as crimped continuous filaments and/or as short filaments. As a result, in particular the softness of the nonwoven fabric can be improved and the flexural stiffness reduced.
To attain this object, the invention also teaches an apparatus for making a nonwoven fabric comprising at least one nonwoven web of filaments, in particular for carrying out a method described above, wherein furthermore the apparatus has at least one filament-making device, in particular at least one spinning beam, and at least one receiving device, in particular at least one foraminous belt, for depositing the filaments to form the nonwoven web, wherein furthermore at least one calender roller, in particular a calender or calender roller pair comprising the calender roller, is provided for consolidating the nonwoven fabric, and wherein in addition at least one hot-fluid main consolidater, in particular at least one hot-air main consolidater for consolidation or main consolidation of the nonwoven fabric is provided.
It is within the scope of the invention that the apparatus has at least one preconsolidater located downstream of, in particular immediately downstream of, the at least one filament-making device or the at least one spinning beam, preferably at least one hot-fluid preconsolidater, preferably at least one hot-air preconsolidater, for preconsolidating the nonwoven fabric, and wherein the at least one hot-fluid preconsolidater or the at least one hot-air preconsolidater is particularly preferably a hot-air knife and/or as a hot-air field.
Expediently, the foraminous belt of the apparatus according to the invention is an endlessly rotating foraminous belt. It is within the scope of the invention that the at least one filament-making device or the at least one spinning beam is configured to produce a spunbonded nonwoven web from continuous filaments, in particular from crimped continuous filaments. If the nonwoven fabric according to one embodiment of the invention is made as a nonwoven laminate of at least two nonwoven webs or nonwoven fabric layers, it is within the scope of the invention that at least two filament-making devices, in particular at least two spinning beams, are provided and that preferably all the filament-making devices or spinning beams are configured of making spunbonded nonwoven webs from continuous filaments, in particular from crimped continuous filaments. Quite particularly preferably, the at least one filament-making device or the at least one spinning beam, preferably all the filament-making devices or all the spinning beams of the apparatus according to the invention, are adapted to produce multicomponent filaments or bicomponent filaments. It is further within the scope of the invention that the apparatus is configured to produce at least one nonwoven web from crimped continuous filaments. Preferably, at least one filament making device or at least one spinning beam is adapted of making crimped continuous filaments. When using several spinning beams for the apparatus according to the invention, at least one spinning beam or at least two spinning beams or all the spinning beams are adapted for the production of crimped continuous filaments.
A very expedient configuration of the invention is characterized in that for the filaments or continuous filaments spun with at least one filament-making device or with at least one spinning beam, at least one cooler for cooling the filaments or filaments and at least one stretcher connected to the cooler for stretching the filaments or filaments are provided. Advantageously, at least one diffuser adjoins the stretcher in the travel direction of the filaments or filaments. A highly recommended embodiment of the invention is characterized in that the subassembly comprising the cooler and the stretcher is a closed unit and that no further air is supplied from outside into this subassembly apart from the supply of cooling air in the cooler. Expediently the filaments or filaments leaving the diffuser are deposited directly on the receiving device or on the foraminous belt.
According to a preferred embodiment of the apparatus according to the invention, the at least one calender roller, in particular the calender or pair of calender rollers comprising the calender roller is provided in the travel direction F of the nonwoven fabric upstream or downstream of the at least one hot-fluid main consolidater. According to a preferred embodiment, the at least one hot-fluid main consolidater is provided in the travel direction F of the nonwoven fabric upstream of the calender roller and in particular upstream of the calender comprising the calender roller. According to a quite particularly preferred embodiment, the at least one hot-fluid main consolidater is provided in the travel direction F of the nonwoven fabric downstream of the calender roller and in particular downstream of the calender having the calender roller.
According to a further preferred embodiment of the apparatus according to the invention, the at least one calender roller has a complementary embossing pattern of embossing elements for introducing an embossing pattern comprising a plurality of embossments into the nonwoven fabric. With such a calender roller having a complementary embossing pattern of embossed elements, the embossing pattern of embossments described above can be introduced into the nonwoven fabric. In addition to this calender roller for introducing an embossing pattern of embossments into the nonwoven fabric, the calender or the pair of calender rollers expediently has a second or further calender roller that is a smooth roller with a smooth outer surface.
It has proven particularly useful that the embossing elements of the complementary embossing pattern of the calender roller each have a pressing area of 0.05 to 0.6 mm², preferably of 0.06 to 0.4 mm², more preferably of 0.07 to 0.25 mm², particularly preferably of 0.08 to 0.15 mm², quite particularly preferably of 0.09 to 0.12 mm². In the context of the invention, “pressing area” means in particular the area of the embossing elements of the calender roller provided of making the embossing area of the embossments. If the embossing elements of the calender roller are configured, for example, as cylindrical embossing elements to produce an embossing area with a punctuate or circular geometry in plan view, the pressing area of the embossing elements corresponds in particular to the area of the top side of the cylinder. When the embossing elements of the calender roller are configured to create an embossing area with a punctuate or circular geometry in plan view, for example, are frustoconical, i.e. with a flank angle, the pressing area of the embossing elements corresponds in particular to the top surface of the truncated cone. One embodiment of the invention uses several flank angles for the embossing elements, wherein the embossing elements preferably have smaller flank angles in the region provided for contact with the nonwoven fabric than further towards the base of the calender roller. The flank angle gradation can be accomplished stepwise or continuously. Within the scope of the invention, the calender roller for introducing an embossing pattern of embossing elements into the nonwoven fabric is configured, with regard to its complementary embossing pattern or with regard to the arrangement and configuration of the embossing elements, in particular in such a way that an embossing pattern with the parameters or properties described above can be made in the nonwoven fabric.
It is within the scope of the invention that the embossing elements of the complementary embossing pattern of the at least one calender roller each have an embossing height in the range from 0.3 to 1.2 mm, preferably from 0.4 to 0.9 mm, particularly preferably from 0.5 to 0.8 mm. “Embossing height” means in particular the height difference between the pressing area of an embossing element and the base of the calender roller. This embodiment is based on the discovery that during a calendering process with such a calender roller, compaction of the nonwoven fabric can be at least largely minimized.
To attain this object, the invention further teaches a nonwoven fabric which is made according to a method described above and/or with an apparatus described above.
According to a particularly preferred embodiment of the nonwoven fabric according to the invention, the nonwoven fabric has an embossing pattern comprising a plurality of preferably not interconnected embossments, wherein the embossments preferably each have an embossing area of 0.05 to 0.6 mm², preferably of 0.06 to 0.4 mm², more preferably of 0.07 to 0.25 mm², particularly preferably of 0.08 to 0.15 mm²and very particularly preferably of 0.09 to 0.12 mm²and/or wherein the embossing areas of the embossments in plan view preferably have at least one geometry selected from the group: “punctuate or circular, elliptical, square, rectangular, diamond-shaped, polygonal, linear, wavy”. It is preferred that the embossing areas or the embossments of the embossing pattern each have the same or substantially the same geometry. In principle, however, it is also within the scope of the invention that the embossing pattern has embossing areas or embossments of different geometries. A quite particularly preferred embodiment of the invention is characterized in that the embossing areas of the embossments or of all the embossments are punctuate or circular in plan view. In the context of the invention, “geometry” of the embossments means in particular the geometry of the embossing areas of the embossments in plan view.
A preferred embodiment of the nonwoven fabric according to the invention is characterized in that the aspect ratio of each of the embossing area of the embossments is less than 4, preferably less than 3, particularly preferably less than 2, for example equal to 1. In this context, “aspect ratio” of the embossing area means in particular the ratio of the greatest length or longitudinal extension of the embossing area of an embossment to the greatest width or width extension of the embossing area of the embossment and, for example, the ratio of the lengths of the axes of symmetry. In the case of a punctuate or circular geometry of the embossing area of an embossment, for example, the aspect ratio is 1. In the case of an elliptical geometry of the embossing area of an embossment, the aspect ratio corresponds, for example, to the ratio of the length of the major axis or major semi-axis to the length of the minor axis or minor semi-axis of the ellipse. In the case of a rectangular geometry of the embossing area of an embossment in plan view, the aspect ratio corresponds, for example, to the ratio of the length of the rectangle to the width of the rectangle. In the case of a diamond-shaped geometry of the embossing area of an embossment, for example, the aspect ratio corresponds to the ratio of the length of the longer diagonals to the length of the shorter diagonals of the diamond. In the case of a square geometry of the embossing area of an embossment in plan view, the aspect ratio is equal to 1. For curved lines, the aspect ratio of the enclosing rectangle preferably describes the aspect ratio of the embossing area.
It is preferred that the nonwoven fabric has a mass per unit area of less than 200 g/m², in particular less than 150 g/m², preferably less than 100 g/m², preferably less than 75 g/m², particularly preferably less than 50 g/m², and quite particularly preferably less than 30 g/m²and/or that the nonwoven has a thickness of 0.1 to 1.0 mm, preferably of 0.15 to 0.8 mm, preferably of 0.2 to 0.65 mm, particularly preferably of 0.25 to 0.55 mm. It is quite particularly preferred that the mass per unit area of the laminate is 10 g/m²to 80 g/m², preferably 15 g/m²to 60 g/m², preferably 15 g/m²to 30 g/m². It is also within the scope of the invention that the nonwoven fabric has a thickness h of at least 0.3 mm, in particular of at least 0.45 mm, preferably of at least 0.55 mm, preferably of at least 0.6 mm, particularly preferably of at least 0.625 mm. “Thickness h” means in particular the greatest thickness or total thickness of the nonwoven fabric transversely, in particular perpendicularly or substantially perpendicularly to its planar extension in the nonembossed regions of the nonwoven fabric. The thickness or total thickness h of the nonwoven fabric is measured in particular according to the method WRT 120.6(05)—Option A.
It lies within the scope of the invention that the nonwoven fabric has an abrasion resistance of at least Class 2 according to Martindale, preferably Class 1 according to Martindale and/or that the nonwoven fabric has a maximum flexural stiffness with a cantilever of at most 100 mm, preferably of at most 90 mm, preferably of at most 80 mm, particularly preferably of at most 70 mm and quite particular preferably of at most 65 mm. This embodiment is based on the discovery that the nonwoven fabric is then characterized by a very satisfactory abrasion resistance and/or that the nonwoven fabric has an advantageously low flexural stiffness and in particular an improved drapability compared to the known measures or nonwoven fabrics. This contributes in an advantageous manner to the solution of the technical problem and in particular to a compromise of optimal nonwoven fabric properties. The abrasion resistance of the nonwoven fabric is determined in the context of the invention in particular using a Martindale abrasion tester according to the following test method:
In particular the “SDL Atlas M235 Martindale Tester” is used as the test device. The procedure for determining the abrasion resistance is preferably based on WSP20.5(05), wherein the following deviations from WSP20.5(05) are provided in particular: the surface (top/bottom) is tested separately; at least 10, preferably at least 20 tests are carried out per sample and surface, wherein the test specimens are taken uniformly from the area of the sample, the final result being the arithmetic mean. The test specimens are to be obtained from a representative position, for example not just from the edge, since the test or the deviations in the result should not be influenced by macroscopic deviations, such as poor process control, but only by typical (local) fluctuations; the tested sample is stretched on standard felt and mounted in the lower holder; the same nonwoven fabric is used as the moving upper friction surface with the side to be tested against each other; this piece is attached together with the PU foam patch (e.g. from SDL Atlas); 9 kPa contact pressure; 32 cycles, i.e. two full rounds of the Lissajous figure; after each of the tests the pair (test specimen and upper friction surface) is exchanged;

- the samples are rated from 1 to 5, with 1 being the best rating. For example, if the mean is 1 on the top and 3 on the bottom, the sample is rated 1 overall. Only the changes in the nonwoven are evaluated; if the nonwoven previously showed similar defects, these can be overlooked. This means strands of filaments, groups or bundles of filaments on the surface. If a test specimen clearly exhibits these defects from the outset, the test specimen should be excluded in case of doubt.

Grade 1: Virtually no change when viewed from above. The surface may be slightly loosened, but the filaments may only loosen and not form larger or longer clumps. When viewed from the side, the pile height of the loose filaments must not exceed 5 mm. Individual filaments or filaments may be pushed together to form a small ball <2 mm in diameter.
Grade 2: in addition to the above damage pattern (Grade 1): Filaments are loosened and matted with neighboring filaments to form an elongated agglomerate. These groups of filaments are called “strands” or “strings or bundles”. These strands are 5 to 40 mm long and are connected to the substrate at least every 10 mm. A strand is max. 5 mm high (5 mm above the surface) and max. 2 mm wide.
Grade 3: The above “strands” are no longer connected to the substrate along their length, possible connections are >10 mm apart or the strands here are only connected to the specimen at the start and end point. It is possible to lift and move these strands e.g. with a needle.
Grade 4: The strands are connected to neighboring strands to form a network. “Spider web”.
Grade 5: The sample is further destroyed, first hole formation has occurred.
Within the scope of the invention, the flexural stiffness of the nonwoven fabric is determined in particular according to the method “WSP 90.1 (05) Standard Test Method for Stiffness of Nonwoven: Fabrics Using the Cantilever Test”.
It is within the scope of the invention that the strength of the nonwoven fabric in the machine direction (MD direction) is at least 8 N/5 cm, in particular at least 10 N/5 cm, preferably at least 15 N/5 cm, preferably at least 17.5 N/5 cm, particularly preferably at least 20 N/5 cm, quite particularly preferably at least 22.5 N/5 cm. In the context of the invention, “machine direction” or “(MD direction)” means in particular the travel direction F of the nonwoven fabric on the receiving device. The strength of the nonwoven fabric in the machine direction is determined within the scope of the invention in particular according to the following method: “Determination of tensile strength (based on Edana 20.2-89)”: in N/5 cm; with 50 mm sample width; 100 mm clamping length; 200 mm/min test speed.
According to a preferred embodiment of the invention, the nonwoven fabric is a nonwoven laminate composed of at least two nonwoven webs or nonwoven fabric layers.
The invention is based on the discovery that with the method according to the invention a nonwoven fabric can be provided that is characterized by an optimal compromise between advantageous mechanical properties, a sufficient thickness and/or voluminosity, a low stiffness or good drapability and an advantageous abrasion resistance. As a result of the combination according to the invention of a consolidation with at least one calender roller, in particular with at least one calender or calender roller pair comprising the calender roller and with at least one hot-fluid main consolidater, an optimal compromise between these properties can be achieved. It should be emphasized that these nonwoven fabric properties can be achieved very reliably and nevertheless with relatively simple measures within the framework of the method according to the invention. The method according to the invention is also characterized by optimal flexibility. According to a preferred embodiment, the nonwoven fabric properties can be further optimized by the temperature relations between the calender roller and/or calender and hot-fluid main consolidater, as well as by the components of the filaments or filaments and by the configuration of the filaments or filaments. If, according to a preferred embodiment, an embossing pattern comprising a plurality of embossments and, according to a quite particularly preferred embodiment, an embossing pattern comprising a plurality of embossments with a relatively small embossing area is introduced into the nonwoven fabric, any impairment of the optical properties of the resulting nonwoven fabric can moreover be almost completely avoided, wherein the nonwoven fabric nevertheless retains the advantageous mechanical properties resulting from such a calendering process or embossing process. In summary, it can be stated that within the scope of the invention an optimal compromise between the nonwoven fabric properties explained above can be achieved. Due to the flexibility of the process, for example with regard to the temperatures used for the consolidation steps or with regard to the configuration of the filaments or filaments, the nonwoven fabric properties can be further optimized according to the preferred embodiments of the method according to the invention.
The invention is explained in more detail hereinafter with reference to embodiments:
In the following three embodiments, only the consolidation or main consolidation of the nonwovens differs, whereby the following parameters and specifications apply to all three embodiments (Examples 1 to 3):
The examples relate to a spunbonded nonwoven fabric composed of two spunbonded nonwoven webs or nonwoven fabric layers spun with a first spinning beam and a second spinning beam. The mass per unit area of the resulting nonwoven fabric was 20 g/m². The foraminous belt speed was 315 m/min. The filaments were each made or deposited as crimped continuous filaments in the form of bicomponent filaments, with the filaments of the first spinning beam having an eccentric core-sheath configuration with a D-shape of the core and the filaments of the second spinning beam having a side-by-side configuration. Polyethylene (DOW Aspun 6850+2 wt. % white dye additive) was used as the first component for the filaments of the first spinning beam. Polypropylene was used as the second component for the filaments of the second spinning beam (Exxon pp 3155+5 wt. % Borealis HL712FB+1 wt. % lubricant additive). The mass ratio of the first component to the second component was 50:50. Polyethylene (DOW Aspun 6834+2 wt. % white dye additive) was used as the first component for the filaments of the second spinning beam. Polypropylene was used as the second component for the filaments of the second spinning beam (Exxon pp 3155+1 wt. % Borealis HL712FB+1 wt. % lubricant additive). The mass ratio of the first component to the second component was 40:60. The throughput for the first beam was 145 kg/h/m and for the second beam 180 kg/h/m.
After the first beam, a preconsolidation with a hot-air knife (650 m³/h/m; 145° C., 90 mm length) and a preconsolidation with a hot-air field (1.5 m/s; 135° C., 900 mm length) were carried out. After the second beam, a preconsolidation was carried out with a hot-air knife (625 m³/h/m; 145° C., 90 mm length) and a consolidation or main consolidation is implemented as described hereinafter with a hot-air field having three different consecutive temperature zones (length of each temperature zone 1200 mm each), which were operated at different temperatures in the different embodiments. Subsequently, consolidation was carried out using a calender as indicated. The filaments of the first nonwoven web or nonwoven fabric layer had an average titer of 1.3 den. The filaments of the second nonwoven web or nonwoven fabric layer had an average titer of 2.0 den.
For the consolidation or the main consolidation of the nonwovens of this embodiments (Examples 1 to 3), the following common conditions and specifications apply: The calender had a total pressing area of the embossing elements of 4% and 41.7 Fig/cm², as well as embossing elements with a circular pressing area; the pressing area of the embossing elements had a diameter of 0.35 mm and thus a pressing area of approximately 0.096 mm²; the spacing between the embossing elements determined by analogy to the smallest spacing d between two embossments described above was 1.2 mm; the calender had an upper calender roller with embossing elements and a lower calender roller with a smooth surface. Located in the travel direction F of the nonwoven fabric downstream of the calender was a hot-air main consolidater in the form of an omega oven with a diameter of 1414 mm and an active, flow-through length of 3500 mm (air velocity: 0.8 m/s). The cantilever and Martindale values given below were measured as described above; in the Martindale data, “top” is the side assigned to the calender roller with embossing elements and “bottom” is the side assigned to the foraminous belt.

Example 1

Consolidation or main consolidation with the hot-air field after the second spinning beam with three different consecutive temperature zones: 120° C./130° C./80° C.; calender surface temperature: 129° C. for the calender roller with embossing elements, 123° C. for the smooth roller; calender linear load: 30 N/mm; omega oven temperature: 80° C.
This resulted in a nonwoven fabric with a strength in the machine direction (MD direction) of 20.7 N/5 cm, a thickness of 0.45 mm and a cantilever of 65 mm, as well as an abrasion resistance of Class 1 (top)/Class 1 (bottom) according to Martindale. The result is a product that is characterized by very advantageous abrasion resistance, by a very advantageously low cantilever value, a sufficient strength and a satisfactory thickness.

Example 2

Consolidation or main consolidation with the hot-air field after the second spinning beam with three different consecutive temperature zones: 120° C./130° C./130° C.; calender surface temperature: 121° C. for the calender roller with embossing elements, 127° C. for the smooth roller; calender linear load: 30 N/mm; omega oven temperature: 128° C.
This resulted in a nonwoven fabric with a strength in the machine direction (MD direction) of 26.6 N/5 cm, a thickness of 0.39 mm and a cantilever of 77 mm, as well as an abrasion resistance of Class 1 (top)/Class 1 (bottom) according to Martindale. This therefore resulted in a product that is characterized by very advantageous abrasion resistance, by an advantageously low cantilever value, very advantageous strength and a sufficient thickness.

Example 3 (State of the Art or not According to the Invention)

Consolidation or main consolidation with the hot-air field after the second spinning beam with three different consecutive temperature zones: 120° C./130° C./130° C.; calender: open, i.e. no nonwoven contact or consolidation with the calender; omega oven temperature: 138° C.; thus no combined consolidation with the calender.
This resulted in a nonwoven fabric with a strength in machine direction (MD direction) of 21.3 N/5 cm, a thickness of 0.53 mm and a cantilever of 105 mm, as well as an abrasion resistance of Class 2.5 (top) and Class 1 (bottom) according to Martindale. This therefore resulted in a product that was characterized on one side of the nonwoven fabric by a disadvantageous abrasion resistance, by a disadvantageous cantilever value, sufficient strength and advantageous thickness.

The invention is explained in more detail below with reference to a drawing that merely represents an embodiment. In the figures in schematic representation:

FIG. 1 is a vertical section through an apparatus according to the invention,

FIG. 2 is a vertical section through a part of the apparatus according to FIG. 1 ,

FIG. 3 is a plan view of a nonwoven fabric according to the invention, and

FIG. 4 is a cross-section along line A-A according to FIG. 1 .

FIG. 1 shows an apparatus 14 according to the invention for carrying out the method according to the invention and for making a nonwoven fabric 1 comprising two nonwoven webs 2, 2′ of crimped continuous filaments 10. The apparatus preferably and here, comprises two spinning beams 3, 3′ that are preferably and here each adapted to produce a spunbonded nonwoven web 2, 2′ from crimped continuous filaments 10 in the form of bicomponent filaments. In addition, according to the preferred embodiment, an endlessly circulating foraminous belt 4 is provided for depositing the continuous filaments 10 to form the nonwoven web 2, 2′. The apparatus 14 preferably and here comprises a calender roller 5 for introducing an embossing pattern 11 (FIGS. 3 and 4 ) consisting of a plurality of nonconnected embossments 12 into the nonwoven fabric 1. This calender roller 5 preferably and here is part of a calender 6 comprising a pair of calender rollers 5, 7. Preferably and here the calender roller 5 of the calender 6 has a complementary embossing pattern 15 of embossing elements 16 that preferably each have a pressing area 17 of 0.05 to 0.6 mm². Pressing surface 17 refers in particular to the area of the embossing elements 16 of the calender roller 5 provided of making an embossing area 13 of the embossments 12 of the nonwoven fabric 1. Preferably and here according to FIG. 1 , the embossing elements 16 of the calender roller 5 are configured to be frustoconical and the pressing area 17 corresponds to the top surface of the frustrated cone. The other or further calender roller 7 of the calender 6 is preferably and here a smooth roller 7 with a smooth outer surface.
According to a particularly preferred embodiment and here according to FIG. 1 , the apparatus 14 has a hot-air main consolidater 8 that is preferably in the travel direction F of the nonwoven fabric downstream of the calender roller 5 or downstream of the calender 6. Preferably and here, the hot-air main consolidater 8 is a hot-air oven. Expediently and here, the apparatus 14 further comprises two preconsolidaters in the form of hot-air preconsolidaters 9, 9′. The hot-air preconsolidaters 9, 9′ are preferably and here in the travel direction F of the nonwoven fabric 1 upstream of the calender roller 5 or upstream of the calender 6. Preferably and here according to FIG. 1 , the hot-air preconsolidaters 9, 9′ are each directly downstream of a spinning beam 3, 3′ for preconsolidating the deposited nonwoven web 2, 2′. A first hot-air preconsolidater 9 is preferably directly downstream of a first spinning beam 3 in the travel direction F of the nonwoven fabric 1, and is then followed by a second spinning beam 3′, to which the second hot-air Preconsolidater 9′ is immediately downstream. The hot-air preconsolidaters 9, 9′ are preferably hot-air knives and/or as hot-air fields.
Within the scope of the method according to the invention and here according to FIG. 1 , a nonwoven web 2 composed of crimped continuous filaments 10 is first made by the first spinning beam 3 and deposited on the foraminous belt 4. The nonwoven web 2 is then preferably and here, preconsolidated by the hot-air preconsolidater 9. Thereafter, a second nonwoven web 2′ made of crimped continuous filaments 10 is expediently made by the second spinning beam 3′ and deposited on the first nonwoven web 2. The second nonwoven web 2′ or the laminate of the first nonwoven web 2 and the second nonwoven web 2′ is then recommendably preconsolidated with the second hot-air preconsolidater 9′ and then preferably detached from the foraminous belt 4 and fed to the calender 6 comprising the calender roller 5. The calender roller 5 of the calender 6 preferably here introduces an embossing pattern 11 comprising a plurality of embossments 12 into the nonwoven fabric 1 and the nonwoven fabric 1 is expediently consolidated in the process. This is then preferably followed by consolidation or main consolidation of the nonwoven fabric 1 by at least one hot-air main consolidater 8.
FIG. 2 shows the basic structure of a part of the apparatus 14 according to the invention of making a nonwoven web 2 according to the spunbond method, comprising a spinneret or the spinning beam 3 for spinning the continuous filaments 10 for the spunbonded nonwoven web 2 from continuous filaments 10. The continuous filaments 10 spun by the spinneret or the spinning beam 3 are introduced into a cooler 18 with a cooling chamber 19. Preferably and here, air supply cabins 20, 21 one above the other are provided on two opposite sides of the cooling chamber 19. Air of different temperatures is preferably introduced into the cooling chamber 19 from the air supply cabins 20, 21 one above the other.
It is recommended and here that a stretcher 22 for stretching the continuous filaments 10 is provided downstream of the cooler 18 in the filament-travel direction. Expediently and here, the stretcher 22 has an intermediate passage 23 that connects the cooler 18 to a stretching shaft 24 of the stretcher 22. Preferably and here, the subassembly comprising the cooler 18, the intermediate passage 23 and the stretching shaft 24 is a closed unit and apart from the supply of cooling air in the cooler 18, no further air is supplied from the outside into this subassembly.
Expediently and here, a diffuser 25, through which the continuous filaments 10 are guided, adjoins the stretcher 22 in the filament-travel direction. After passing through the diffuser 25, the continuous filaments 10 are preferably and here deposited on a receiving device, here a foraminous belt 4. The foraminous belt 4 is preferably and here an endlessly rotating foraminous belt 4. It is within the scope of the invention that the foraminous belt 4 is permeable to air, so that suction of process air from below through the foraminous belt 4 is possible.
FIGS. 3 and 4 show a nonwoven fabric 1 according to the invention with at least one nonwoven web 2 of filaments. In this embodiment, the nonwoven fabric 1 comprises two nonwoven webs 2, 2′ composed of continuous filaments 10 and is particularly a nonwoven laminate. The continuous filaments 10 may preferably and here be crimped continuous filaments 10. Preferably and here, the nonwoven fabric 1 is a spunbonded nonwoven fabric comprising two spunbonded nonwoven webs 2, 2′ composed of crimped continuous filaments 10. In this embodiment, the crimped continuous filaments 10 may be bicomponent filaments with an eccentric core-sheath configuration, wherein the sheath of the continuous filaments 10 preferably consists of or substantially consists of polyethylene and wherein the core of the continuous filaments 10 consists of or substantially consists in particular of at least one polyester and/or polypropylene.
FIGS. 3 and 4 also show that the nonwoven fabric 1 has an embossing pattern 11, wherein the embossing pattern 11 consists of a plurality of Ralf embossments 12. The embossing pattern 11 is preferably and here a regular embossing pattern 11 whose individual embossments 12 are preferably and here distributed at regular intervals on the nonwoven fabric 1.
Within the scope of the invention and here, the embossments 12 each have an embossing area 13 of 0.05 to 0.6 mm². “Embossing area 13” of an embossment 12 means, within the scope of the invention and here, in particular the embossed area of an embossment 12, wherein when determining the size of the embossing area 13, the material overhang or material projection that may be formed during the pressing or embossing process and at least partially enclosing the embossment 12 is not part of the embossing area 13 of an embossment 12. This can be seen particularly in FIG. 4 in the hatched representation. Further preferably and here, the embossing area 13 of the individual embossments 12 of the embossing pattern 11 is the same size or substantially the same size. Preferably and here according to the figures, the embossing areas 13 of the embossments 12 have a punctuate or circular geometry in plan view. Quite particularly preferably and here, the embossing pattern 11 has the same or same-sized embossments 12 or substantially the same or same-sized embossments 12 with a homogeneous distribution of embossments 12 of the same geometry or of substantially the same geometry.
Within the scope of the invention, the smallest spacing d between two embossments 12 of each of the embossing pattern 11 is 0.6 to 3.0 mm. “Smallest spacing d” between two embossments 12 means in particular the smallest spacing d between two immediately adjacent embossments 12 of the embossing pattern 11, thus preferably the smallest spacing d between an embossment 12 and the embossment 12 of the embossing pattern 11 that is closest to it. Furthermore, the smallest spacing d between two embossments 12 refers in particular to the smallest spacing d between the embossing boundaries of two embossments 12, i.e. to the smallest spacing between the two embossments 12 along the interposed nonembossed area of the nonwoven fabric 1.
The thickness h of the nonwoven fabric 1 is expediently 0.15 to 0.75 mm. In the embodiment according to the figures, the thickness h of the nonwoven fabric 1 may be approximately 0.4 mm. “Thickness h” means the greatest thickness or total thickness of the nonwoven fabric 1 transversely, in particular perpendicularly or substantially perpendicularly to its planar extension in the nonembossed areas of the nonwoven fabric 1. This can be seen particularly in FIG. 4 .

Claims

1. A method of making a nonwoven fabric comprising a nonwoven web of filaments, wherein

filaments are made with at least one filament-making device,

the filaments are subsequently deposited on a receiving device to form the nonwoven web,

the nonwoven web or the nonwoven fabric is consolidated with a calender roller, and

the nonwoven fabric is additionally consolidated or main consolidated with a t least one hot-fluid main consolidater.

2. The method according to claim 1, wherein the nonwoven fabric is detached from the receiving device prior to the consolidation with the calender roller and/or prior to the main consolidation with the hot-fluid main consolidater.

3. The method according to claim 1, wherein the consolidation of the nonwoven fabric with the calender roller is carried out before or after consolidation or main consolidation of the nonwoven fabric with the hot-fluid main consolidater.

4. The method according to claim 1, wherein the nonwoven fabric after being deposited on the receiving device and before consolidation or main consolidation is initially preconsolidated with a preconsolidater.

5. The method according to claim 1, wherein the hot-fluid main consolidater is a hot-air oven, an omega oven, a multidrum oven, a single belt oven, or a double belt oven.

6. The method according to claim 1, wherein the residence time of the nonwoven fabric in the hot-fluid main consolidater is 0.4 s to 25 s or the fluid velocity of the fluid of the hot-fluid main consolidater is 0.4 to 3 m/s.

7. The method according to claim 1, wherein a surface temperature of the calender roller is higher than the fluid temperature T2 of the hot-fluid main consolidater, is lower than the fluid temperature of the hot-fluid main consolidater, or is identical or substantially identical to the fluid temperature of the hot-fluid main consolidater.

8. The method according to claim 1, wherein the filaments of the nonwoven web are made or spun as continuous multicomponent filaments.

9. The method according to claim 8, wherein the multicomponent filaments comprise a first component that consists or substantially consists of a polyolefin or the multicomponent filaments comprise a second or further component that consists or substantially consists of a thermoplastic material.

10. The method according to claim 8, wherein the continuous filaments are made or spun as multicomponent or bicomponent filaments with side-by-side configuration or with core-sheath configuration.

11. The method according to claim 9, wherein a surface temperature T1 of the calender roller or the fluid temperature T2 of the hot-fluid main consolidater in relation to a melting temperature Tm of the first component of the multicomponent filaments or bicomponent filaments satisfies the following condition: (Tm−15° C.)<T1 and/or T2<(Tm+15° C.).

12. The method according to claim 1, wherein an embossing pattern comprising a plurality of embossments is introduced into the nonwoven fabric by the calender roller, the embossments each having an embossing area of 0.05 to 0.6 mm².

13. The method according to claim 12, wherein the embossing pattern is made such that a smallest spacing d between two adjacent embossments of each of the embossing pattern is 0.6 to 3.0 mm.

14. The method according to claim 12, wherein the embossing pattern is made such that a proportion of the total embossing area of the embossing pattern to a total surface area of the nonwoven fabric is 2 to 15%.

15. The method according to claim 1, wherein a nonwoven fabric with at least two nonwoven webs is made from

first filaments made by a first filament-making device, and are then deposited on a receiving device, to form the nonwoven web,

second filaments are made by a second filament-making device and are then deposited on the first nonwoven web to form a laminate with the second nonwoven web,

the laminate composed of the at least two nonwoven webs is consolidated with a calender roller, and

the laminate is additionally consolidated or main consolidated with a hot-fluid main consolidater.

16. An apparatus for making a nonwoven fabric comprising a nonwoven web of filaments, the apparatus comprising:

a filament-making device,

a receiving device for deposition of the filaments to form the nonwoven web,

a calender roller for consolidating the nonwoven web, and

a hot-fluid main consolidater for main consolidation of the nonwoven web.

17. The apparatus according to claim 16, wherein the calender roller is provided in the travel direction of the nonwoven fabric upstream or downstream of the hot-fluid main consolidater.

18. The apparatus according to claim 16, wherein the calender roller has a complementary embossing pattern of embossing elements for introducing an embossing pattern of a plurality of embossments into the nonwoven fabric, the embossing elements each having a pressing area of 0.05 to 0.6 mm².

19. A nonwoven fabric made by a process according to claim 1.

20. The nonwoven fabric according to claim 19, wherein the nonwoven fabric has an embossing pattern of a plurality of embossments that each have an embossing area of 0.05 to 0.6 mm²or the embossing areas of the embossments in plan view have a geometry selected from the group: “punctuate or circular, elliptical, square, rectangular, diamond-shaped, polygonal, linear, wavy.”

21. The nonwoven fabric according to claim 20, wherein the nonwoven fabric has a mass per unit area of less than 200 g/m²or the nonwoven fabric has a thickness h of 0.1 to 1.0 mm.

22. The nonwoven fabric according to claim 20, wherein the nonwoven fabric has an abrasion resistance of at least Class 2 according to Martindale or wherein the nonwoven fabric has a maximum flexural stiffness with a cantilever of at most 100 mm.

23. The nonwoven fabric according to claim 20, wherein the nonwoven fabric is a nonwoven laminate composed of at least two nonwoven webs or nonwoven fabric layers.