Method and Apparatus for Making a Nonwoven Textile

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 Tof 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 Tof the at least one hot-fluid main consolidater or lower than the fluid temperature Tof the at least one hot-fluid main consolidater or is identical or substantially identical to the fluid temperature Tof 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 Tof 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 Tof 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.)<Tand/or T<(Tm+15° C.), preferably (Tm−10° C.)<Tand/or T<(Tm+10° C.), preferably (Tm−8° C.)<Tand/or T<(Tm+8° C.), particularly preferably (Tm−7° C.)<Tand/or T<(Tm+7° C.), quite particularly preferably (Tm−6° C.)<Tand/or T<(Tm+6° C.), for example (Tm−5° C.)<Tand/or T<(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 Tof the at least one calender roller and/or the fluid temperature Tof the at least one hot-fluid main consolidater preferably satisfies the above-mentioned condition. The surface temperature Tcan preferably have the relationship to the fluid temperature Tdescribed above, so that Tcan preferably be higher than Tor lower than Tor identical to T. 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 Tdescribed 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 mm, preferably 0.06 to 0.4 mm, preferably 0.07 to 0.25 mm, particularly preferably 0.08 to 0.15 mm, and quite particularly preferably 0.09 to 0.12 mm. It is within the scope of the invention that the embossments each have an embossing area of less than 0.3 mm, preferably less than 0.2 mm, preferably less than 0.18 mm, particularly preferably less than 0.15 mm, very particularly preferably less than 0.12 mm, for example less than 0.1 mm. 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 lightD 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 mm, preferably of 0.06 to 0.4 mm, more preferably of 0.07 to 0.25 mm, particularly preferably of 0.08 to 0.15 mm, quite particularly preferably of 0.09 to 0.12 mm. 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 mm, preferably of 0.06 to 0.4 mm, more preferably of 0.07 to 0.25 mm, particularly preferably of 0.08 to 0.15 mmand very particularly preferably of 0.09 to 0.12 mmand/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/m, in particular less than 150 g/m, preferably less than 100 g/m, preferably less than 75 g/m, particularly preferably less than 50 g/m, and quite particularly preferably less than 30 g/mand/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/mto 80 g/m, preferably 15 g/mto 60 g/m, preferably 15 g/mto 30 g/m. 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.