Nonwovens and spunbonded nonwovens made from endless filaments

Abstract

The present invention relates to a spunbond nonwoven fabric made of endless filaments, in particular crimped endless filaments, characterized in that the filaments are formed as bicomponent or multicomponent filaments and have an eccentric core / sheath structure, the sheath of which has a constant thickness d over at least 20% of the circumference of the filament in the cross section of the filament.

Description

[Technical field]

[0001] The present invention relates to a spunbond nonwoven fabric made of endless filaments, in particular a nonwoven fabric made of crimped endless filaments, the filaments being designed as bicomponent filaments or as multicomponent filaments. The invention further relates to an apparatus for producing a spunbond nonwoven fabric from endless filaments, in particular from crimped endless filaments. It is within the scope of the invention that the endless filaments and the endless filaments are made of a thermoplastic material. The endless filaments differ from staple fibers, which have a much shorter length, from 10 mm to 60 mm, due to their quasi-infinite length. [Background technology]

[0002] For many technical applications, it is desirable to produce so-called high loft nonwovens. These are nonwovens that are relatively thick and at the same time relatively soft. However, the production of nonwovens is generally not without problems, since they must simultaneously have sufficient strength and abrasion resistance. In this respect, the task is contradictory. Setting a higher strength or abrasion resistance usually comes at the expense of the thickness and softness of the nonwoven. Conversely, increasing the thickness and maintaining a high softness usually results in a nonwoven with low strength and abrasion resistance. So far, few satisfactory solutions are known. -Hot nonwovens are usually produced with the help of crimping or crimping of the fibers / filaments. In particular, for this purpose, bicomponent filaments in a side-by-side configuration or bicomponent filaments with an eccentric or asymmetric core-sheath structure are used. However, many previously known nonwovens made with crimped fibers are characterized by a relatively high defect rate. In particular, unwanted agglomerates are found in the nonwoven, which have a negative effect on the uniformity. In this respect, too, there is a need for improvement. Summary of the Invention [Problem to be solved by the invention]

[0003] The present invention is based on the technical problem of identifying a nonwoven fabric having an optimal thickness and optimal softness, and at the same time having sufficient strength or tensile strength and sufficient abrasion resistance, which should also be as defect-free as possible, in particular as free from agglomerates as possible.The present invention is also based on the technical problem of providing an apparatus for producing such a nonwoven fabric. [Means for solving the problem]

[0004] In order to achieve this technical problem, the present invention proposes a spunbonded nonwoven fabric (1) consisting of endless filaments (2), in particular crimped or crimped endless filaments (2), formed as bicomponent or multicomponent filaments and having an eccentric core / sheath structure, in which the sheath (3) of the filaments (2) has a constant or substantially constant thickness d in the filament cross-section over at least 20%, in particular at least 25%, preferably at least 30%, preferably at least 35% and very preferably at least 40% of the filament circumference. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0005] Within the scope of the present invention, the sheath thickness of the filaments is the average thickness or mean sheath thickness, in particular the average sheath thickness associated with the filaments. The sheath thickness or sheath thickness is conveniently measured using a scanning electron microscope. Moreover, it is within the scope of the present invention that the sheath thickness or mean sheath thickness, which is not associated with thermal preconsolidation or solidification, is therefore measured in particular on filaments or filament cross sections that are not at or part of the bond points. In other words, the sheath thickness is measured on the filaments or on filament cross sections outside the bond points or bond points.

[0006] Furthermore, within the scope of the present invention, the endless filaments (continuous filaments, endless filaments) of the nonwoven material consist or essentially consist of a thermoplastic material. Crimped endless filaments means, in particular in the context of the present invention, that the crimped filaments each have crimps with at least 1.5, preferably at least 2, preferably at least 2.5 and very preferably at least 3 loops per centimeter of their length. A preferred embodiment of the present invention is characterized in that the endless filaments of the spunbonded nonwoven fabric according to the present invention have crimps with 1.8 to 3.2, in particular 2 to 3, loops per centimeter of their length. In particular, according to the Japanese standard JIS L-1015-1981, the number of crimp loops or crimp arcs (loops) per cm of filament length is measured by counting the crimps with a pretension of 2 mg / den in (1 / 10 mm) based on the unstretched length of the filament. A sensitivity of 0.05 mm is used for measuring the number of crimp loops. The measurement can conveniently be carried out using a "Favimat" device from the company TexTechno, Germany. For this, see Favimat "-Geraet der Firma TexTechno, Germany. Dazu wird auf die Veroeffentlichung "Automatic Crimp Measurement on Staple Fibres", Denkendorf Kolloquium", "Textile Mess- und Prueftechnik", 9.11.99, Dr. Ulrich Moerschel (in particular page 4, Figure 4). For this purpose, the filaments (or filament samples) are removed from the deposition or deposition belt as filament balls before further consolidation and measured.

[0007] According to the invention, bicomponent or multicomponent filaments having an eccentric core-sheath structure are used for the spunbond nonwoven. Within the scope of the invention, the sheath of the filaments completely surrounds the core. Furthermore, within the scope of the invention, the material or plastic of the sheath has a lower melting point than the material or plastic of the core of the filaments.

[0008] The invention is based on the finding that in the spunbonded nonwoven fabric according to the invention, a high thickness and high softness, nevertheless sufficient strength and abrasion resistance, can be achieved without problems. In the context of the invention, strength means in particular the strength of the nonwoven fabric in the machine direction (MD). In the nonwoven fabric according to the invention, a completely sufficient strength can be achieved without a significant reduction in thickness. The invention is further based on the finding that due to the cross-sectional structure of the filaments according to the invention, an optimal crimp can be achieved and, above all, can be easily adjusted by varying the parameters, whereby the desired thickness and the desired softness are achieved, while at the same time a sheath material surrounding the entire filament circumference can be effectively used for thermal preconsolidation. During this thermal preconsolidation, bonding points are created between the filaments with the help of the low-melting sheath material of the filaments, so that the filaments have the optimal strength and abrasion resistance according to the invention with the filament properties according to the invention, while nevertheless maintaining a sufficient thickness and softness. It should also be emphasized that the nonwoven fabric according to the invention can be formed surprisingly without defects and, above all, is largely free of destructive agglomerates. As a result, a very homogeneous fiber layer or nonwoven layer can be obtained.

[0009] The nonwoven fabric according to the invention preferably has a thickness of more than 0.5 mm, in particular a thickness of more than 0.55 mm and preferably a thickness of more than 0.6 mm. It is within the scope of the invention that the nonwoven fabric according to the invention has a strength in the machine direction (MD) of more than 20 N / 5 cm, in particular more than 25 N / 5 cm. The above thickness and strength values ​​are in particular between 10 and 50 g / m 2 Base weight, preferably 15 to 40 g / m2 and preferably 18 to 35 g / m 2 This applies to nonwoven fabrics that fall within the above standard weight range.

[0010] Also within the scope of the present invention, the core of the filament occupies more than 40%, in particular more than 50%, preferably more than 60%, preferably more than 65% and very preferably more than 70% of the cross-sectional area of ​​the filament. According to one embodiment of the present invention, the core of the filament occupies more than 75% of the cross-sectional area of ​​the filament.

[0011] The core of the filament, viewed in the filament cross section, is formed in the form of a circular segment and preferably has at least one, in particular arcuate, or substantially arcuate circumferential cross section with respect to its circumference (perimeter). The core of the filament, viewed in the filament cross section, further preferably has at least one, in particular linear or substantially linear, circumferential cross section. According to a particularly preferred embodiment of the invention, the core of the filament, viewed in the filament cross section, consists of an arcuate or substantially arcuate circumferential cross section and a directly adjacent linear or substantially linear circumferential cross section. In proven embodiments of the invention, the arcuate or substantially arcuate circumferential cross section is characterized in that it comprises more than 40%, in particular more than 50%, preferably more than 60%, preferably more than 65% of the circumference of the core.

[0012] A preferred embodiment is characterized in that the sheath of the filament seen in the filament cross section - outside the sheath area with a constant or substantially constant thickness - is formed in the shape of a circular segment (annular part) or substantially in the shape of a circular segment, which in this case advantageously has at least one, in particular arc-shaped or substantially arc-shaped, circumferential cross section and preferably has at least one, in particular linear or substantially linear, circumferential cross section with respect to its circumference. The sheath part of the circular segment preferably consists of an arc-shaped or substantially arc-shaped circumferential part and a linear or substantially linear circumferential part, which are expediently directly adjacent parts.

[0013] Within the scope of the present invention, the sheath of the filaments viewed from the filament cross section has a constant or substantially constant thickness, in particular more than 45%, more than 50%, preferably more than 55%, preferably more than 60% of the filament circumference. According to a preferred embodiment of the present invention, the thickness of the sheath in the region of constant or substantially constant thickness is less than 10%, in particular less than 8%, preferably less than 7% and preferably less than 3% of the filament diameter or the maximum filament diameter. The thickness of the sheath in the region of constant or substantially constant thickness is at least 0.5%, in particular at least 1% and preferably at least 1.2% of the filament diameter or the maximum filament diameter. - Preferably, the spinneret for producing the filaments is selected or set so that the filaments leaving the spinneret in a state not yet drawn have the relative thickness values ​​or thickness percentages defined above or below. However, it is also within the scope of the present invention that these relative thickness values ​​also apply to the sheath of the filaments in the finished spunbonded nonwoven fabric.

[0014] According to a preferred embodiment of the invention, the thickness of the sheath in its regions of constant or substantially constant thickness in the finished spunbond nonwoven fabric is 0.05 to 5 μm, in particular 0.1 to 4 μm, preferably 0.1 to 3 μm, preferably 0.1 to 2 μm, very preferably 0.15 to 1.5 μm and particularly preferably 0.1 to 0.9 μm.

[0015] The ratio of the mass of the core to the mass of the sheath in the filaments of the spunbonded nonwoven fabric according to the invention is preferably 90:10 to 40:60, preferably 90:10 to 60:40, and more preferably 85:15 to 70:30. -A particularly preferred embodiment of the invention is characterized in that in the cross section of the filaments, the distance between the centers of gravity of the core from the center of gravity of the sheath is 5% to 38%, in particular 6% to 36% and preferably 6% to 34%, 7% to 33% of the filament diameter or the maximum filament diameter. Furthermore, a very preferred embodiment of the invention is characterized in that in the cross section of the filaments, the distance between the centers of gravity a is 5% to 36% of the filament diameter or the maximum filament diameter when the mass ratio of the core:sheath is 85:15 to 70:30. It is preferred that in the cross section of the filaments, the distance between the centers of gravity a is 12% to 40% of the filament diameter D or the maximum filament diameter D when the mass ratio of the core:sheath is 70:30 to 60:40. When the core:sheath mass ratio is 60:40a, 18 to 36%, and especially 20 to 31% of the filament diameter or the maximum filament diameter is preferred to 45:55, the distance between the central body of the core and the sheath is small.

[0016] Particularly preferred embodiments of the invention are characterized in that the core and / or the sheath of the filaments consist or essentially consist of at least one polyolefin. The fact that the core and / or the sheath consist, for example "essentially", of a plastic means, in particular within the scope of the invention, that in addition to this plastic, additives are also present in the core and / or the sheath. "Essentially" means, according to the invention, that the core and / or the sheath comprise at least 90% by weight, preferably at least 95% by weight and preferably at least 97% by weight of the respective plastic. - According to a preferred embodiment of the invention, both the core and the sheath of the filaments consist respectively of at least one polyolefin, in particular a polyolefin, or essentially of at least one polyolefin, in particular essentially of a polyolefin. Particularly preferred embodiments of the invention are characterized in that the sheath of the filaments consists or essentially consists of polyethylene and the core of the filaments consists or essentially consists of polypropylene. - It has already been mentioned that it is within the scope of the invention that the sheath of the filaments consists or essentially consists of a low-melting substance or plastic compared to the core of the filaments. In principle, said copolymers of polyolefins can also be used in the context of the present invention, either alone in the core and / or sheath or in a mixture with at least one homopolyolefin. Mixtures of homopolyolefins can also be used in the core and / or sheath. Blends with other plastics are also possible.

[0017] In the present invention, if polypropylene is used or if polypropylene is used in the core, it should be a polypropylene with a melt flow rate (MFR) of more than 25 g / 10 min, in particular more than 40 g / 10 min, preferably more than 50 g / 10 min, preferably more than 55 g / 10 min and very preferably more than 60 g / 10 min. The melt flow rate (MFR) is measured in particular according to ASTM D1238-13 (condition B, 2.16 kg, 230°C). In the present invention, if polyethylene is used as a component, in particular as a component of the sheath, it is a polyethylene with a melt flow rate of less than 35 g / 10 min, in particular less than 25 g / 10 min, preferably less than 20 g / 10 min. For polyethylene, the melt flow rate is measured in particular according to ASTM D1238-13 at 190°C / 2.16 kg.

[0018] In one embodiment of the invention, the filament core and / or sheath are characterized in that they consist or essentially consist of at least one polyester and / or at least one copolyester. In a preferred embodiment, the filament core consists or essentially consists of at least one polyester, in particular polyester, and the sheath consists or essentially consists of at least one polyester and / or copolyester, preferably having a lower melting point than the core components. It is also possible for the core to consist or essentially consist of at least one polyester and / or at least one copolyester and the sheath to consist or essentially consist of at least one polyolefin. As a polyester copolymer, polyethylene terephthalate (PET) is particularly suitable, and as a polyester copolymer, PET copolymer (Co-PET) is particularly suitable. However, as these polyesters, polybutylene terephthalate (PBT) or polylactide (PLA) or copolymers thereof can also be used. Furthermore, within the scope of the invention, polymers or mixtures or blends of polymers can also be used for the filament core and / or sheath. In an embodiment demonstrated in the present invention, the core and / or sheath of the filaments is characterized in that it consists or essentially consists of at least one plastic from the group "polyolefins, polyolefin copolymers, in particular polyethylene, polypropylene, polyethylene copolymers, polypropylene copolymers, polyesters, polyester-copolymers, in particular polyethylene terephthalate (PET), PET copolymers, polybutylene terephthalate (PBT), PBT copolymers, polylactides (PLA), PLA copolymers", although mixtures or blends of said polymers can also be used for the core and / or sheath.A preferred embodiment of the invention is characterized in that the core of the filament consists or essentially consists of at least one plastic from the group "polypropylene, polypropylene copolymers, polyethylene terephthalate (PET), PET copolymers, polybutylene terephthalate (PBT), PBT copolymers, polylactide (PLA), PLA copolymers".

[0019] It is within the scope of the present invention that the filament titer used in the spunbonded nonwoven fabric of the present invention is between 1 and 12 denier. According to a preferred embodiment, the filament titer is between 1.0 and 2.5 denier, in particular between 1.5 and 2.2 denier, preferably between 1.8 and 2.2 denier. This titer or this filament diameter has been found to be particularly useful from the viewpoint of solving the technical problem according to the present invention.

[0020] In a well-documented embodiment, the spunbond nonwoven according to the invention is characterized in that it is a thermally preconsolidated and / or thermally final consolidated nonwoven having thermal bond points or thermal bond points between the filaments. According to a very preferred embodiment, the spunbond nonwoven according to the invention is a nonwoven thermally preconsolidated with hot air and / or thermally bonded nonwoven. Thermal preconsolidation of the nonwoven can in principle also be carried out by compressive rolling. It is also within the scope of the invention that thermal preconsolidation or consolidation of the nonwoven is carried out with the aid of a calendar. -The invention is based on the finding that, due to the inventive design of the cross-section of the filaments, optimal preconsolidation or thermal preconsolidation of the spunbond nonwoven is possible, while nevertheless allowing sufficient crimping and thus maintaining the desired thickness of the nonwoven. In this respect, an optimal compromise between sufficient crimping and, as a result, sufficient thickness and optimal consolidation of the nonwoven is possible. The crimp can be set in a targeted manner by varying the cross-sectional parameters of the filaments, allowing the desired thickness to be accurately and functionally created without excessive crimp, and further facilitating effective pre-consolidation of the nonwoven.

[0021] To solve the technical problem, the present invention also provides an apparatus for producing spunbonded nonwovens, in particular from crimped endless filaments, with at least one spinneret (10), which apparatus or spinneret (10) is adapted to produce multicomponent or bicomponent filaments with an eccentric core / sheath structure, the sheath (3) of the filaments (2) having a constant or substantially constant thickness d in the filament cross section over at least 20%, in particular at least 25%, preferably at least 30%, preferably at least 35%, very preferably at least 40% of the filament circumference, and the filaments (2) can be deposited on a deposition device, in particular a deposition screen belt (20). Within the scope of the present invention, the apparatus is a spunbond apparatus. The apparatus preferably comprises a cooling device for cooling the filaments and a drawing device connected thereto for stretching the filaments. Furthermore, the apparatus preferably comprises at least one diffuser connected to the drawing device. A particularly preferred embodiment of the invention is characterized in that the unit consisting of the cooling device and the stretching device is designed as a closed unit and that apart from the supply of cooling air in the cooling device, no further air is supplied into this unit from the outside.

[0022] Within the scope of the present invention, after the filaments have been deposited on the deposition device or on the deposition screen belt, a thermal preconsolidation of the fiber deposit or nonwoven web can be carried out. For this purpose, according to a preferred embodiment of the present invention, at least one thermal preconsolidation device is provided. A preferred embodiment of the present invention is characterized in that the at least one thermal preconsolidation device is designed as a hot air preconsolidation device. The thermal preconsolidation device advantageously comprises a hot air knife and / or at least one hot air oven. According to another embodiment of the present invention, the thermal preconsolidation or consolidation can also be carried out with a pressure roller or a compression roller and / or at least one calender can be used for the preconsolidation or consolidation. According to a preferred embodiment of the device according to the invention, the thermal preconsolidation of the deposited nonwoven web is first carried out using at least one hot air knife, in particular a hot air knife, and then a further thermal preconsolidation is carried out using at least one hot air oven, in particular a hot air oven. In a preferred embodiment of the invention, the spunbonded nonwoven is only preconsolidated with hot air and / or only final consolidated with hot air. -The invention is based on the knowledge that in the filament cross-section according to the invention, on the one hand, the entire circumference of the filament is available for thermal preconsolidation, and on the other hand, the degree of thermal preconsolidation or thermal preconsolidation can be increased by targeted selection of parameters, in particular the thickness of the sheath, so that on the one hand, an optimal consolidation of the nonwoven is achieved, and on the other hand, the crimp of the filaments is not too much impaired in order to maintain the desired thickness of the nonwoven. Within the scope of the invention, in particular for the filament cross-section according to the invention, a very simple and targeted setting of the nonwoven properties is possible, in particular with regard to thickness, softness and strength. Above all, in the present invention, the crimp can be adjusted without any problems and therefore controlled.

[0023] The nonwoven fabric according to the invention is characterized on the one hand by an optimal thickness and softness, and on the other hand by a satisfactory strength or abrasion resistance. The crimping of the filaments can be easily kept within the desired limits due to the configuration of the filaments according to the invention, so that the result of the disclosure according to the invention is a controllable crimp. With optimal strength and abrasion resistance that are easy to set, a nearly defect-free nonwoven fabric can be obtained, which is above all essentially free of destructive agglomerates. In summary, it can be said that within the scope of the present invention, an optimal compromise between the strength and thickness or softness properties of the nonwoven fabric can be achieved, and that this compromise can be achieved in a simple manner with a surprisingly uniform filament volume.

[0024] The invention will be explained in more detail below with reference to the drawings which show only one exemplary embodiment, which is shown in the schematic diagram: [Brief description of the drawings]

[0025] [Figure 1] Figure 1 shows cross-sectional views of an endless filament, a) a conventional eccentric core-sheath structure and b) an eccentric core-sheath structure according to the present invention. [Diagram 2] FIG. 2 shows a cross-sectional view of an endless filament according to the invention. [Diagram 3] FIG. 3 shows diagrammatically the dependence of the distance a between the centres of gravity of the core and the sheath of an endless filament according to the invention on the thickness d of the sheath of the endless filament in a region of constant thickness d of the sheath. [Figure 4] FIG. 4 shows a vertical cross-section of an apparatus according to the invention for producing a spunbond nonwoven fabric according to the invention.

[0026] FIG. 1 shows a comparison of a cross section of an endless filament 2 with a conventional eccentric core-sheath structure (FIG. 1a) and an endless filament 2 with an eccentric core-sheath structure according to the invention (FIG. 1b). In both cases, the filament is a bicomponent filament with a first component of thermoplastic component in the sheath 3 and a second component made of thermoplastic in the core 4. The component in the sheath 3 has a lower melting point than the component in the core 4. FIG. 1b and FIG. 2 also show that in an endless filament 2 for a spunbonded nonwoven fabric 1 according to the invention in an exemplary embodiment, the sheath 3 of the filament 2 preferably has a constant thickness d over more than 50% of the filament circumference in the filament cross section. Preferably, in an exemplary embodiment, the core 4 of the filament 2 occupies more than 65% of the area of ​​the filament cross section of the filament 2.

[0027] In a preferred exemplary embodiment, the core 4 of the filament 2 according to the invention is designed - when viewed in the filament cross section - in the shape of a circular segment. In an exemplary embodiment, the core 4 has, with respect to its circumference, an arcuate circumferential cross section 5 and a linear circumferential cross section 6. In fact, in an exemplary embodiment, the arcuate circumferential cross section of the core 4 accounts for more than 65% of the circumference of the core 4. In an exemplary embodiment, the sheath 3 of the filament 2, when viewed in the filament cross section, is designed in the shape of a circular segment outside the sheath area having a constant thickness d. This circular segment 7 of the sheath 3 has, with respect to its circumference, in a preferred exemplary embodiment, an arcuate circumferential cross section 8 and a linear circumferential cross section 9.

[0028] Preferably, the thickness d or average thickness d of the sheath 3 in the constant thickness region is preferably 1% to 8%, in particular 2% to 10% of the filament diameter D. In an exemplary embodiment, the thickness d of the sheath 3 in the constant thickness region may be 0, 2 to 3 μm.

[0029] Figure 2 shows the distance a between the center of gravity of the sheath 3 and the center of gravity of the core 4 of an endless filament 2 according to the invention. This distance between the centers of gravity of the core 4 and the sheath 3 is in principle larger for a given mass or area ratio of the core and sheath material in an endless filament 2 according to the invention than in a conventional endless filament 2 having an eccentric core-sheath arrangement. The distance a between the center of gravity of the core 4 from the center of gravity of the sheath 3 of a filament 2 according to the invention is preferably 5-40% of the filament diameter D or the maximum filament diameter D. - Figure 3 shows diagrammatically the dependence of the area of ​​the core 4 and the distance between the center of the sheath 3 for a constant thickness d of the sheath 3 of an endless filament 2 according to the invention in a preferred embodiment of the invention. The dependence is shown for area fractions of the core 4 of 75%, 67% and 50%. The sheath 3 distance a and the constant sheath thickness d are each given in micrometers. The underlying endless filament 2 according to the invention described here has a filament diameter D of 18 μm.

[0030] The following table shows the distances between the centers of gravity of the core 4 and the sheath 3 for endless filaments 2 with different filament diameters D of 18 μm and different core:sheath area ratios (75:25, 67:33 and 50:50). The left side of the table shows these distances for an endless filament according to the invention with an eccentric core-sheath configuration (eC / S filaments according to the invention) with a constant sheath thickness d of 1 μm. The right side of the table shows the distances for an endless filament 2 with a conventional eccentric core-sheath configuration (conventional eC / S filaments) with a sheath thickness d' of 1 μm at the point of minimum distance between the core 4 and the outer surface. The center body distance a is shown in absolute values ​​in μm and relative values ​​(%) to the filament diameter D.

[0031] [Table 1]

[0032] As is evident from the table, the distance between the centers of gravity is significantly greater for endless filaments 2 with a core-sheath structure according to the invention than for endless filaments 2 with a conventional core-sheath structure, both for the same filament diameter D and the same core:sheath area ratio. Maintaining the distance between the center of gravity of the core 4 area and the center of gravity of the sheath 3 is an essential feature of the invention that is of particular importance. The distance between the centers of gravity represents the lever arm on which the crimping forces from the two materials act, and is therefore an essential factor for the degree of crimping.

[0033] Preferably, in an exemplary embodiment, the core 4 of the filament 2 according to the invention consists of polypropylene and the sheath 3 of the filament 2 consists of polyethylene. This is a particularly preferred embodiment that has proven very well within the scope of the present invention. It is essentially within the scope of the invention for the melting point of the thermoplastic material of the sheath 3 to be lower than the melting point of the thermoplastic material of the core 4 of the endless filament 2 according to the invention.

[0034] According to a preferred embodiment of the invention, the endless filaments 2 of the spunbonded nonwoven fabric 1 according to the invention have a fineness of 1.5 to 2.5 denier, preferably 1.5 to 2.2 denier, preferably 1.8 to 2.2 denier. This fineness itself has proven to be particularly useful in solving technical problems. It is also within the scope of the invention that the spunbonded nonwoven fabric 1 according to the invention is a thermally pre-consolidated spunbonded nonwoven fabric, in particular one having thermal bonding points or bonding points between the endless filaments 2. According to a particularly preferred embodiment, the spunbonded nonwoven fabric 1 according to the invention is a spunbonded nonwoven fabric 1 thermally pre-consolidated by hot air. Such a spunbonded nonwoven fabric 1 has proven to be very useful in solving technical problems.

[0035] 4 shows an apparatus according to the invention for producing a spunbonded nonwoven fabric 1 according to the invention, which nonwoven fabric 1 consists in particular of crimped endless filaments 2. The spunbonding apparatus comprises a spinneret 10 or spinneret for spinning the endless filaments 2. The spinneret 10 or the apparatus is designed such that the endless filaments 2 are produced as multi- or bi-component filaments with an eccentric core-sheath configuration, i.e. preferably as endless filaments 2 whose sheath 3 has a constant thickness d over at least 50% of the filament circumference in the filament cross section.

[0036] Preferably, in an exemplary embodiment, the spun endless filaments 2 are introduced into a cooling device 11 having a cooling chamber 12. In a suitable exemplary embodiment, air supply cabins 13, 14 arranged one above the other are arranged on two opposite sides of the cooling chamber 12. Air of different temperatures is suitably introduced into the cooling chamber 12 from the air supply cabins 13, 14 arranged one above the other.

[0037] According to a preferred embodiment and according to the embodiment according to Fig. 4, a monomer suction device 15 is arranged between the spinneret 10 and the cooling device 11. In this monomer suction device 15, interfering gases occurring during the spinning process can be removed from the device. These gases can be, for example, monomers, oligomers or decomposition products and similar substances.

[0038] Downstream of the cooling device 11 in the direction of filament flow, a stretching device 16 is provided for stretching the endless filaments 2. In a preferred exemplary embodiment, the stretching device 16 has an intermediate channel 17 connecting the cooling device 11 to a stretching shaft 18 of the stretching device 16. According to a particularly preferred and exemplary embodiment, the unit from the cooling device 11 and the stretching device 16 or the unit from the cooling device 11, the intermediate channel 17 and the stretching shaft 18 is designed as a closed unit, so that apart from the supply of cooling air in the cooling device 11, there is no further air supply from outside into this unit.

[0039] In a preferred exemplary embodiment, the drawing device 16 is adjacent to a diffuser 19, through which the endless filaments 2 are guided, in the direction of filament flow. After passing through the diffuser 19, the endless filaments 2 are deposited on a deposition device, which is preferably designed in an exemplary embodiment as a deposition screen belt 20. The deposition screen belt 20 is preferred and in an exemplary embodiment is designed as an infinitely rotating deposition screen belt 20. It is designed to be air permeable, so that suction from below through the screen belt 20 is possible.

[0040] According to a preferred and exemplary embodiment, the diffuser 19 or the diffuser 19 arranged directly above the depositing screen belt 20 has two opposing diffuser walls, and two lower diffuser wall sections 21, 22 are provided, which are preferably designed asymmetrically with respect to the central plane M of the diffuser 19. In an exemplary embodiment, the inlet diffuser wall section 21 forms a smaller angle β with the central plane M of the diffuser 19 than the outlet diffuser wall section 22. This preferred embodiment is of particular importance in the context of the present invention, and has proven to be particularly effective, in particular with regard to solving the technical problem. The terms inlet and outlet here relate to the running direction of the depositing screen belt 20 or the conveying direction of the nonwoven web.

[0041] According to a preferred embodiment of the invention, the inlet end 23 of the diffuser 19 is provided with two opposing secondary air inlet gaps 24, 25, each of which is arranged on one of two opposing diffuser walls. A lower secondary air volumetric flow rate is preferably introduced through the inlet-side secondary air inlet gap 24 with respect to the conveying direction of the deposition screen belt 20 than through the outlet-side secondary air inlet gap 25. This embodiment is also of particular importance in the context of the present invention.

[0042] In a preferred exemplary embodiment, there is at least one suction device, by means of which air or process air can be sucked through the deposition screen belt 20 in a main suction area 27 of the deposition area 26 of the filaments 2. The main suction area 27 below the deposition screen belt 20 is separated by a suction partition 28 at the inlet area of ​​the deposition screen belt 20 and at the outlet area of ​​the deposition screen belt 20, respectively. Preferably, in an exemplary embodiment, a second suction area 29 is connected downstream of the main suction area 27 in the conveying direction of the deposition screen belt 20, in which area air or process air can be sucked through the deposition screen belt 20. The suction speed v2 of the process air through the deposition screen belt 20 in the second suction area 29 is equal to the suction speed v of the main suction area 27. H It is preferable that the temperature is lower than 100°C.

[0043] A particularly preferred embodiment is characterized in that the end of the suction partition 28 facing the depositing screen belt 20 has a vertical distance A relative to the depositing screen belt 20 of 10 to 250 mm, in particular 25 to 200 mm, preferably 28 to 150 mm, preferably 29 to 140 mm and very preferably 30 to 120 mm. According to a further preferred embodiment, in the region of this suction partition 28 facing the depositing screen belt 20, a partition section designed as a spoiler part 30 is connected, which constitutes said end of the suction partition 28 facing the depositing screen belt 20. Within the scope of the present invention, the end of this spoiler part 30 facing the depositing screen belt 20 has a horizontal distance C from an imaginary extension of the remaining associated suction partition 28, which corresponds to at least 80% of the vertical distance A. Distances A and C are not shown in the figures. According to a preferred embodiment - shown in FIG. 4 - the suction partition 28 has a partition section, which is angled from the remaining part of the suction partition 28 and is designed as a spoiler section 30 on the screen belt side. In an exemplary embodiment, this spoiler section 30 is provided on the outlet side suction partition 28 of the main suction area 27. According to a proven embodiment of the invention, the spoiler section 30 is more angled with respect to a vertical line oriented perpendicular to the screen belt surface than the partition section of the further opposite suction partition 28 facing the screen belt 20. The spoiler section 30 has a greater length of its projection on the deposition screen belt surface than the projection of the corresponding angled or bent partition section of the further opposite suction partition 28 facing the deposition screen belt 20. With respect to the screen belt side end, the spoiler section 30 is preferably at a greater distance from the deposition screen belt 20 than the end of the partition section of the further opposite suction partition 28 facing the deposition screen belt 20. The embodiment with the spoiler section 30 ensures a very continuous transition of the suction speed from the main suction area 27 to the subsequent area in the conveying direction of the depositing screen belt 20, in particular to the secondary suction area 29. By the arrangement of the spoiler section 30, a uniform, continuous and steady reduction of the suction speed can be achieved.In this way, defects in the nonwoven web or spunbonded nonwoven fabric 1 of the invention, which may arise for example from a sudden change in suction speed due to a backflow effect (so-called blowback effect) in the transition area between the main suction area 27 and the secondary suction area 29, can be largely avoided. The embodiment with the spoiler section 30 is therefore a very preferred embodiment which contributes to solving the technical problem of the present invention.

[0044] In a preferred exemplary embodiment, at least one thermal preconsolidation device for thermal consolidation of the nonwoven web is provided in the transport direction of the nonwoven web downstream of the deposition area 26. The thermal preconsolidation device is preferably arranged in or on the second suction area 29. According to a particularly preferred embodiment, the thermal preconsolidation device works with hot air, and it is particularly preferred that this thermal preconsolidation device, connected downstream of the main suction area 27, is a hot air knife 31. By means of the thermal preconsolidation device, the bonding points between the filaments 2 of the nonwoven web can be realized in a simple manner. The sheath 3 of the endless filaments 2 of the invention running all around can be used very effectively to form the thermal bonding points.

[0045] According to one embodiment of the present invention, at least two thermal preconsolidation devices are provided for preconsolidating the nonwoven web. The first thermal preconsolidation device in the conveying direction of the nonwoven web is preferably a hot air knife 31, and a second thermal preconsolidation device, preferably in the form of a hot air stove 32, is connected downstream of this hot air knife 31 in the conveying direction of the depositing screen belt 20. Within the scope of the present invention, air is also sucked through the depositing screen belt 20 in the region of the hot air stove 32. Furthermore, within the scope of the present invention, the suction speed of the air sucked in by the depositing screen belt 20 decreases from the main suction zone 27 towards the further suction zones in the conveying direction of the depositing screen belt 20.

[0046] 4 shows a spunbond device according to the invention with a spinneret 10, i.e. a spinning bar. It is also within the scope of the invention that the spunbond device according to the invention can be used in the context of a two-beam system or a multi-beam system. According to one embodiment, several spunbond devices according to the invention can be used here one after the other. Furthermore, the present invention includes the following items. [Item 1] 1. A spunbond nonwoven fabric (1) consisting of endless filaments (2), in particular crimped endless filaments (2), characterized in that the filaments (2) are formed as bicomponent or multicomponent filaments and have an eccentric core / sheath structure, the sheath (3) of the filaments (2) having a constant or substantially constant thickness d in the filament cross-section over at least 20%, in particular at least 25%, preferably at least 30%, preferably at least 35% and very preferably at least 40% of the filament circumference. [Item 2] 4. The spunbond nonwoven fabric according to any one of items 1 to 3, wherein the core (4) of the filament (2) occupies more than 50% of the area of ​​the filament cross section of the filament (2), in particular more than 55%, preferably more than 60%, more preferably more than 65%, and very preferably more than 70%. [Item 3] 3. The spunbond nonwoven fabric according to claim 1 or 2, characterized in that the core (4) of the filament (2) is formed in the shape of a circular segment when viewed in the filament cross section and has, with respect to its circumference, at least one particularly arcuate circumferential portion (5) or substantially arcuate circumferential portion (5) and at least one particularly straight circumferential portion (6). [Item 4] Item 4. The spunbond nonwoven fabric according to item 3, characterized in that the arcuate circumferential portion (5) of the core (4) occupies more than 50% of the circumference of the core (4), in particular more than 55%, preferably more than 60%, and more preferably more than 65%. [Item 5] 5. The spunbond nonwoven fabric according to any one of claims 1 to 4, characterized in that the sheath (3) of the filaments (2) is formed - when viewed in the filament cross section - in the shape of a circular segment outside the sheath region having a constant thickness d, and this circular segment (7) has, with respect to its circumference, at least one, in particular arc-shaped or substantially arc-shaped circumferential portion (8) and at least one, in particular straight or substantially straight circumferential portion (9). [Item 6] 6. The spunbond nonwoven fabric according to any one of the preceding claims, wherein the sheath (3) of the filaments (2) - when viewed on the filament cross section - has a constant or substantially constant thickness d over more than 45%, in particular over more than 50%, preferably over more than 55% and even more preferably over more than 60% of the filament circumference. [Item 7] 7. The spunbond nonwoven fabric according to any one of the preceding claims, characterized in that the thickness of the sheath (3) in the region of constant or substantially constant thickness d is less than 10%, in particular less than 8%, preferably less than 7% of the filament diameter D or the maximum filament diameter D. [Item 8] 8. The spunbond nonwoven fabric according to any one of items 1 to 7, wherein the thickness of the sheath (3) in the region of constant or substantially constant thickness d is 0.1 to 5 μm, in particular 0.1 to 4 μm, preferably 0.1 to 3 μm, preferably 0.1 to 2 μm, very preferably 0.1 to 0.9 μm. [Item 9] 9. The spunbond nonwoven fabric according to any one of items 1 to 8, wherein the ratio of the mass of the core (4) to the mass of the sheath (3) is 90:10 to 50:50, preferably 90:10 to 60:40, and more preferably 85:15 to 70:30. [Item 10] 10. The spunbond nonwoven fabric according to any one of items 1 to 9, wherein the distance a between the center of gravity of the surface of the sheath (3) and the center of gravity of the surface of the core (4) is 5% to 45%, particularly 6% to 40%, and preferably 6% to 36% of the filament diameter D or the maximum filament diameter D. [Item 11] 11. The spunbond nonwoven fabric according to item 10, wherein the distance a between the centers of gravity is 5% to 45% of the filament diameter D or the maximum filament diameter D when the core:sheath mass ratio is 85:15 to 70:30, and / or the distance a between the centers of gravity is 12% to 40% of the filament diameter D or the maximum filament diameter D when the core:sheath mass ratio is 70:30 to 60:40, and / or the distance a between the centers of gravity is 18% to 36% of the filament diameter D or the maximum filament diameter D when the core:sheath mass ratio is 60:40 to 45:55. [Item 12] 12. The spunbond nonwoven fabric according to any one of the preceding claims, wherein the core (4) and / or the sheath (3) of the filaments (2) consist or consist essentially of at least one polyolefin, in particular both the core (4) and the sheath (3) of the filaments (2) consist or consist essentially of at least one polyolefin, preferably the sheath (3) consists or consists essentially of polyethylene, and preferably the core (4) consists or consists essentially of polypropylene. [Item 13] 13. The spunbond nonwoven fabric according to any one of the preceding claims, characterized in that the core (4) and / or the sheath (3) of the filaments (2) consist or consist essentially of at least one polyester and / or copolyester, in particular the core (4) consists or consist essentially of a polyester and preferably the sheath (3) consists or consist essentially of a copolyester. [Item 14] 14. The spunbond nonwoven fabric according to any one of items 1 to 13, wherein the filament titer is 1.5 to 2.5 denier, particularly 1.7 to 2.3 denier, and preferably 1.8 to 2.2 denier. [Item 15] 15. The spunbond nonwoven fabric according to any one of items 1 to 14, characterized in that the nonwoven fabric (1) is a thermally pre-consolidated and / or thermally final-consolidated nonwoven fabric (1) having bond sites or bond points between filaments. [Item 16] 1. An apparatus for producing a spunbond nonwoven fabric (1) consisting of endless filaments (2), in particular crimped endless filaments (2), comprising at least one spinneret (10), which apparatus or spinneret (10) is configured to produce multicomponent or bicomponent filaments having an eccentric core / sheath structure, in which the sheath (3) of the filaments (2) has a constant or substantially constant thickness d in the filament cross section over at least 20%, in particular at least 25%, preferably at least 30%, preferably at least 35%, very preferably at least 40% of the filament circumference, and in which the filaments (2) can be deposited on a deposition apparatus, in particular a deposition screen belt (20). [Item 17] 17. The apparatus according to item 16, wherein the apparatus comprises a cooling device (11) for cooling the filaments (2) and an adjacent drawing device (16) for elongating the filaments (2), preferably comprising at least one diffuser (19) adjacent the drawing device (16). [Item 18] 18. The apparatus according to item 17, wherein the unit consisting of the cooling device (11) and the stretching device (16) is formed as a closed unit, and apart from the supply of cooling air in the cooling device (11), no further air supply is provided from the outside. [Item 19] 19. The apparatus according to any one of items 16 to 18, wherein at least one thermal preconsolidation device is provided, by means of which the nonwoven web of filaments (2) deposited on the depositing device or depositing screen belt (20) can be thermally preconsolidated. [Item 20] 20. Apparatus according to item 19, characterized in that the thermal preconsolidation device is designed as a hot air preconsolidation device.

Claims

1. A spunbond nonwoven fabric (1) made of endless filaments (2), the filaments (2) being formed as bicomponent or multicomponent filaments and having an eccentric core / sheath structure, the sheath (3) of the filaments (2) having a constant or substantially constant thickness d in the filament cross-section over at least 20% of the filament circumference, The thickness of the sheath (3) in the region of constant or substantially constant thickness d is between 0.1 and 2 μm; The spunbond nonwoven fabric is characterized in that the distance a between the center of gravity of the surface of the sheath (3) and the center of gravity of the surface of the core (4) is 6% to 36% of the filament diameter D or the maximum filament diameter D.

2. 2. The spunbond nonwoven fabric of claim 1, wherein the core (4) of the filament (2) occupies more than 50% of the cross-sectional area of ​​the filament (2).

3. 3. The spunbond nonwoven fabric according to claim 1, characterized in that the core (4) of the filaments (2) is formed in the shape of a circular segment when viewed in the filament cross section and has, with respect to its circumference, at least one arcuate or substantially arcuate circumferential portion (5) and at least one straight or substantially straight circumferential portion (6).

4. 4. The spunbond nonwoven fabric according to claim 3, characterized in that the arcuate circumferential portion (5) of the core (4) occupies more than 50% of the circumference of the core (4).

5. 5. The spunbond nonwoven fabric according to claim 1, characterized in that the sheath (3) of the filaments (2) - when viewed in the filament cross section - is formed in the shape of a circular segment outside a sheath region having a constant thickness d, this circular segment (7) having, with respect to its circumference, at least one arcuate or substantially arcuate circumferential portion (8) and at least one straight or substantially straight circumferential portion (9).

6. 6. The spunbond nonwoven fabric according to claim 1, wherein the sheath (3) of the filaments (2) has - when viewed on the filament cross section - a constant or substantially constant thickness d over more than 45% of the filament circumference.

7. 7. The spunbond nonwoven fabric according to claim 1, wherein the thickness of the sheath (3) in the region of constant or substantially constant thickness d is less than 10% of the filament diameter D or the maximum filament diameter D.

8. 8. The spunbond nonwoven fabric according to claim 1, wherein the thickness of the sheath (3) in the region of constant or substantially constant thickness d is 0.1 to 0.9 μm.

9. The spunbond nonwoven fabric according to any one of claims 1 to 8, wherein the ratio of the mass of the core (4) to the mass of the sheath (3) is from 90:10 to 50:

50.

10. 10. The spunbond nonwoven fabric according to claim 1, wherein the core (4) and / or the sheath (3) of the filaments (2) consists or essentially consists of at least one polyolefin.

11. 11. The spunbond nonwoven fabric according to claim 1, wherein the core (4) and / or the sheath (3) of the filaments (2) consists or essentially consists of at least one polyester and / or copolyester.

12. The spunbond nonwoven fabric according to any one of claims 1 to 11, wherein the filament titer is 1.5 to 2.5 denier.

13. 13. The spunbond nonwoven fabric according to any one of claims 1 to 12, characterized in that the nonwoven fabric (1) is a thermally pre-consolidated and / or thermally final consolidated nonwoven fabric (1) having bond sites or bond points between the filaments.

14. 1. An apparatus for producing a spunbond nonwoven fabric (1) consisting of endless filaments (2), comprising at least one spinneret (10), the apparatus or spinneret (10) being configured to produce multicomponent or bicomponent filaments having an eccentric core / sheath structure, wherein the sheath (3) of the filaments (2) has a constant or substantially constant thickness d in the filament cross-section over at least 20% of the filament circumference, The thickness of the sheath (3) in the region of constant or substantially constant thickness d is between 0.1 and 2 μm; The distance a between the center of gravity of the surface of the sheath (3) and the center of gravity of the surface of the core (4) is 6% to 36% of the filament diameter D or the maximum filament diameter D; The filament (2) can be deposited on a deposition device.

15. 15. Apparatus according to claim 14, further comprising a cooling device (11) for cooling the filaments (2) and an adjacent drawing device (16) for stretching the filaments (2), and at least one diffuser (19) adjacent the drawing device (16).

16. 16. The device according to claim 15, wherein the cooling device (11) and the stretching device (16) are formed as a closed unit, and apart from the supply of cooling air in the cooling device (11), no further air supply is provided from the outside.

17. 17. Apparatus according to any one of claims 14 to 16, wherein at least one thermal preconsolidation device is provided, by means of which the nonwoven web (1) of filaments (2) deposited on the depositing device or depositing screen belt (20) can be thermally preconsolidated.

18. 18. Apparatus according to claim 17, characterized in that the thermal preconsolidation device is designed as a hot air preconsolidation device.

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