EP3771761A1 - Spunbond nonwoven fabric made from endless filaments and device for producing spunbond nonwoven fabric - Google Patents

Abstract

Spunbond nonwoven fabric made from continuous filaments, in particular from crimped continuous filaments, the filaments being designed as bicomponent filaments or multicomponent filaments and having an eccentric core-sheath configuration. The sheath of the filaments, viewed in the filament cross section, has a constant thickness d over at least 20% of the filament circumference.

Description

The invention relates to a spunbond nonwoven fabric made from continuous filaments, in particular from crimped continuous filaments, the filaments being designed as bicomponent filaments or as multicomponent filaments. The invention also relates to a device for producing a spunbond nonwoven fabric from continuous filaments, in particular from crimped continuous filaments. It is within the scope of the invention that the continuous filaments and continuous filaments are made of thermoplastic material. Because of their quasi-endless length, continuous filaments differ from staple fibers, which have much shorter lengths of, for example, 10 mm to 60 mm.

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 these nonwovens is not possible without any problems, since the nonwovens generally have to have sufficient strength and abrasion resistance at the same time. To this extent there is a conflict of objectives. Setting a higher strength or abrasion resistance is normally at the expense of the thickness and the softness of the nonwoven fabric. Conversely, maintaining a large thickness and high softness generally leads to less strong and abrasion-resistant nonwovens. So far, there are hardly any known satisfactory solutions. - A high thickness of nonwovens is normally produced with the help of curling or crimping fibers / filaments. For this purpose, bicomponent filaments with a side-by-side configuration or with an eccentric or asymmetrical core-sheath configuration are used in particular. Many of the previously known nonwovens made from crimping or crimping However, fibers are characterized by a relatively high defect rate. In particular, undesired agglomerates are found in the nonwovens, which adversely affect the homogeneity. In this respect, too, there is a need for improvement.

The invention is based on the technical problem of specifying a nonwoven fabric which has an optimal thickness and optimal softness and at the same time has sufficient strength or tensile strength and sufficient abrasion resistance. In addition, the nonwoven should be as free as possible from defects and, in particular, as free as possible from agglomerates. The invention is also based on the technical problem of specifying a device for producing such a nonwoven fabric.

To solve the technical problem, the invention teaches a spunbond nonwoven fabric made from continuous filaments, in particular from crimped or crimped continuous filaments, the filaments being designed as bicomponent filaments or as multicomponent filaments and having an eccentric core-sheath configuration
and wherein the sheath of the filaments in the filament cross section has a constant thickness or an essentially constant thickness over at least 20%, in particular over at least 25%, preferably over at least 30%, preferably over at least 35% and very preferably over at least 40% of the filament circumference .

It is within the scope of the invention that the thickness of the sheath of the filaments is the mean thickness or mean sheath thickness, specifically preferably the mean sheath thickness in relation to a filament. The jacket thickness or the jacket thicknesses are expediently with Measured using a scanning electron microscope. Furthermore, it is within the scope of the invention that the jacket thickness or the mean jacket thickness is measured on filaments or filament sections that are not involved in a thermal pre-consolidation or consolidation and are therefore in particular not part of bonding points or bonding points. In other words, the sheath thickness is measured on the filaments or on the filament sections outside the bonding points or bonding points.

In addition, it is within the scope of the invention that the continuous filaments of the nonwoven material consist or essentially consist of thermoplastic material. Crimped continuous filaments means in the context of the invention in particular that the crimped filaments each have a crimp of 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 recommended embodiment of the invention is characterized in that the continuous filaments of the spunbond nonwoven fabric according to the invention have a crimp of 1.8 to 3.2, in particular 2 to 3 loops per centimeter of their length. The number of crimped loops or crimped arcs (loops) per centimeter of length of the filaments is measured in particular according to the Japanese standard JIS L-1015-1981 by counting the crimps under a pretension of 2 mg / den in (1/10 mm) based on the unstretched length of the filaments. A sensitivity of 0.05 mm is used to determine the number of curling loops. The measurement is expediently carried out with a "Favimat" device from TexTechno, Germany. Reference is made to the publication "Automatic Crimp Measurement on Staple Fibers", Denkendorf Colloquium "," Textile Mess- und Prüftechnik ", November 9, 1999, Dr. Ulrich Mörschel (especially p. 4, Fig. 4 ) referenced. For this purpose, the filaments (or the filament sample) are / will be removed from the deposit or from the deposit belt as filament balls before further solidification and the filaments are separated and measured.

According to the invention, bicomponent filaments or multicomponent filaments with an eccentric core-sheath configuration are used for the spunbond nonwoven fabric. It is within the scope of the invention that the sheath of the filaments completely surrounds the core. Furthermore, it is within the scope of the invention that the material or the plastic of the jacket has a lower melting point than the material or the plastic of the core of the filaments.

The invention is based on the knowledge that, with the spunbond nonwoven fabric according to the invention, a large thickness and a high softness and nevertheless sufficient strength and abrasion resistance can be achieved without any problems. In the context of the invention, strength means in particular the strength of the nonwoven in the machine direction (MD). With the nonwoven fabric according to the invention, a completely satisfactory strength can be achieved without any appreciable loss of thickness. The invention is further based on the knowledge that, due to the cross-sectional structure of the filaments according to the invention, an optimal crimp can be achieved and, above all, can also be easily adjusted by varying the parameters - whereby the desired thickness and the desired softness is achieved - and at the same time that via Sheath material encircling the entire filament circumference can be used effectively for thermal pre-consolidation. During this thermal pre-consolidation, bonding points are produced between the filaments with the aid of the lower-melting sheath material of the filaments, and these result in the nonwoven fabric according to the invention with the filament properties according to the invention an optimal strength and abrasion resistance of the nonwoven fabric while still maintaining sufficient thickness and softness. It should also be emphasized that the nonwovens according to the invention can be formed surprisingly free of defects and, above all, are largely free of disruptive agglomerates. As a result, a very homogeneous fiber layer or nonwoven layer can be achieved.

A nonwoven fabric according to the invention is recommended to have a thickness of more than 0.5 mm, in particular 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 nonwovens according to the invention have a strength in the machine direction (MD) of more than 20 N / 5 cm, in particular of more than 25 N / 5 cm. The above thickness and strength values apply in particular to nonwovens with a basis weight of 10 to 50 g / m ² , preferably with a basis weight of 15 to 40 g / m ² and preferably with a basis weight of 18 to 35 g / m ² .

It is also within the scope of the invention that the core of the filaments takes up more than 40%, in particular more than 50%, preferably more than 60%, preferably more than 65% and very preferably more than 70% of the area of the filament cross section of the filaments. According to one embodiment of the invention, the core of the filaments takes up more than 75% of the area of the filament cross-section of the filaments.

It is recommended that the core of the filaments, viewed in the filament cross-section, is formed in the shape of a segment of a circle and preferably has at least one, in particular a circular arc-shaped circumferential section or essentially circular arc-shaped circumferential section with regard to its circumference. The core of the filaments in the Viewed filament cross-section, additionally at least one, in particular a linear or substantially linear, circumferential section. According to a particularly preferred embodiment of the invention, the core of the filaments, viewed in the filament cross-section, consists of a circular arc-shaped or essentially circular arc-shaped circumferential section and a linear or essentially linear circumferential section — advantageously directly adjoining it. A proven embodiment of the invention is characterized in that the circular arc-shaped or essentially circular arc-shaped circumferential section of the core takes up over 40%, in particular over 50%, preferably over 60% and preferably over 65% of the circumference of the core.

A recommended embodiment is characterized in that the sheath of the filaments - seen in the filament cross-section - outside the sheath area with the constant or essentially constant thickness is formed in the shape of a segment of a circle or essentially in the shape of a segment of a circle. This circular segment expediently has at least one, in particular a circular arc-shaped or essentially circular arc-shaped, circumferential section and preferably at least one, in particular a linear or essentially linear, circumferential section with regard to its circumference. The jacket section in the form of a segment of a circle preferably consists of a circular arc-shaped or essentially circular arc-shaped circumferential section and a linear or essentially linear circumferential section — expediently directly adjoining it.

It is within the scope of the invention that the sheath of the filaments - seen in the filament cross section - over 45%, in particular over 50%, preferably over 55% and preferably over 60% of the filament circumference having a constant thickness or a substantially constant thickness. According to a preferred embodiment of the invention, the thickness of the jacket in the region of its 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 largest filament diameter. The thickness of the jacket in the region of its constant or essentially constant thickness is expediently at least 0.5%, in particular at least 1% and preferably at least 1.2% of the filament diameter or the largest filament diameter. The spinneret for producing the filaments is preferably selected or set up with the proviso that the filaments leaving the spinneret have the relative thickness values or percentage thickness values for the jacket given above and below in the not yet drawn state. However, it is also within the scope of the invention that these relative thickness values also apply to the sheath of the filaments in the finished spunbond nonwoven fabric.

According to a recommended embodiment of the invention, the thickness of the jacket in the region of its constant or essentially constant thickness in the finished spunbond nonwoven material 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.

It is recommended that the ratio of the mass of the core to the mass of the sheath in the filaments of the spunbond nonwoven fabric according to the invention is 90:10 to 40:60, preferably 90:10 to 60:40 and preferably 85:15 to 70:30. A particularly recommended embodiment of the invention is characterized in that, with respect to the filament cross-section, the distance a of the centroid of the core from the centroid of the sheath is 5% to 38%, in particular 6% to 36% and preferably 6% to 34%, preferably 7% to 33% of the filament diameter or the largest filament diameter. Furthermore, a very preferred embodiment of the invention is characterized in that, with regard to the filament cross section, the distance a between the centers of area of core and sheath with a core: sheath mass ratio of 85:15 to 70:30 is between 5% and 36% of the filament diameter or the largest Filament diameter is. With a core: sheath mass ratio of 70:30 to 60:40, the distance a of the centroids is preferably between 12% and 40% of the filament diameter or the largest filament diameter. With a core: sheath mass ratio of 60:40 to 45:55, the distance a between the centroids of the core and sheath is recommended between 18% and 36%, in particular between 20% and 31% of the filament diameter or the largest filament diameter.

A particularly recommended embodiment of the invention is characterized in that the core and / or the sheath of the filaments consists or essentially consists of at least one polyolefin. The fact that the core and / or the jacket "essentially" consists of a plastic, for example, means in the context of the invention in particular that, in addition to this plastic, additives are also present in the core and / or the jacket. In the context of the invention, “essentially consists” primarily means that the core and / or the jacket comprises 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 recommended embodiment of the invention, both the core and the sheath of the filaments each consist of at least one polyolefin, in particular of a polyolefin or essentially of at least one polyolefin, in particular essentially of one Polyolefin. A particularly preferred embodiment of the invention is characterized in that the sheath of the filaments consists or essentially consists of polyethylene and that the core of the filaments consists of polypropylene or essentially consists of polypropylene. - It was already stated above that it is within the scope of the invention that the sheath of the filaments consists or essentially consists of the lower melting material or plastic compared to the core of the filaments. In principle, copolymers of the aforementioned polyolefins can also be used in the context of the invention, either alone in the core and / or in the shell or in a mixture with at least one homopolyolefin. Mixtures of homopolyolefins can also be used for the core and / or for the shell. Mixtures with other plastics are also possible.

If, in the context of the invention, polypropylene is used or polypropylene is used for the core, it is preferably a polypropylene with a melt flow rate 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). If, in the context of the invention, polyethylene is used as a component, in particular as a component for the jacket, it is expediently a polyethylene with a melt flow rate below 35 g / 10 min, in particular below 25 g / 10 min, preferably below 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.

One embodiment of the invention is characterized in that the core and / or the sheath of the filaments consists or essentially consists of at least one polyester and / or of at least one copolyester. A recommended embodiment is characterized in that the core of the filaments consists or essentially consists of at least one polyester, in particular a polyester, and that the sheath preferably consists of at least one, in particular a polyester and / or copolyester with a lower melting point than the core component exists or essentially exists. It is also possible that the core consists or substantially consists of at least one polyester and / or of at least one copolyester and that the jacket consists or substantially consists of at least one polyolefin. - Polyethylene terephthalate (PET) is particularly suitable as polyester and PET copolymer (Co-PET) is particularly suitable as polyester copolymer. However, polybutylene terephthalate (PBT) or polylactide (PLA) or copolymers of these polyesters can also be used as polyester. It is moreover within the scope of the invention that mixtures or blends of polymers or the polymers mentioned can also be used for the core and / or for the sheath of the filaments. A proven embodiment of the invention is characterized in that the core and / or the sheath of the filaments consists of at least one plastic from the group "polyolefin, polyolefin copolymer, in particular polyethylene, polypropylene, polyethylene copolymer, polypropylene copolymer; polyester, polyester Copolymer, in particular polyethylene terephthalate (PET), PET copolymer, polybutylene terephthalate (PBT), PBT copolymer, polylactide (PLA), PLA copolymer "consists or essentially consists. Mixtures or blends of the aforementioned polymers can also be used for the core and / or shell. It is within the scope of the invention that the plastic of the jacket has a lower melting point than the plastic of the core. A recommended embodiment of the invention is characterized in that the core of the filaments consists of at least one plastic from the group "polypropylene, polypropylene copolymer, polyethylene terephthalate (PET), PET copolymer, polybutylene terephthalate (PBT), PBT copolymer, polylactide (PLA), PLA copolymer" or essentially consists. According to a preferred embodiment, the sheath of the filaments consists of at least one plastic from the group "polyethylene, polyethylene copolymer, polypropylene, polypropylene copolymer".

It is within the scope of the invention that the titer of the filaments used for the spunbond nonwoven according to the invention is between 1 and 12 den. According to a recommended embodiment, the titer of the filaments is between 1.0 and 2.5 den, in particular between 1.5 and 2.2 den and preferably between 1.8 and 2.2 den. This titer or this filament diameter has proven particularly useful in terms of solving the technical problem according to the invention.

A well-proven embodiment is characterized in that the spunbond nonwoven according to the invention is a thermally pre-bonded and / or thermally bonded nonwoven which has thermal bonding points or thermal bonding points between the filaments. According to a very preferred embodiment, the spunbond nonwoven according to the invention is a nonwoven thermally pre-bonded with hot air and / or thermally bonded nonwoven. The thermal pre-consolidation of the nonwoven fabric can in principle also take place by compacting rollers. It is also within the scope of the invention that a thermal pre-consolidation or consolidation of the nonwoven fabric is carried out with the aid of a calender. The invention is based on the knowledge that in the configuration of the cross-sections of the filaments according to the invention, an optimal pre-consolidation or thermal pre-consolidation of the spunbonded nonwovens is possible and nevertheless a sufficient crimp and thus the desired thickness of the nonwoven fabric can be maintained. In this respect, an optimal compromise is possible between sufficient crimp and thus sufficient thickness on the one hand and optimal consolidation of the nonwovens. The crimp can be set in a targeted manner by varying the cross-sectional parameters of the filaments and it is also easy to ensure that the crimp does not become too large and that the desired thickness can be created precisely and reliably and, in addition, an effective pre-consolidation of the Nonwoven fabric can be carried out.

To solve the technical problem, the invention also teaches a device for producing a spunbond nonwoven fabric from continuous filaments, in particular from crimped continuous filaments, at least one spinneret being present, the device or the spinneret being set up with the proviso that multicomponent filaments or bicomponent filaments with an eccentric core-sheath configuration, the sheath of the filaments seen in the filament cross-section over at least 20%, in particular over at least 25%, preferably over at least 30%, preferably over at least 35% and very preferably over at least 40% of the filament circumference having a constant thickness or a substantially constant thickness and wherein the filaments are deposited on a depositing device, in particular on a depositing screen belt. It is within the scope of the invention that the device is a spunbond device. The device preferably has a cooling device for cooling the filaments and a stretching device connected to it for stretching the filaments. The device is also preferably equipped with at least one diffuser connected to the stretching device. - A particularly preferred one Embodiment of the invention is characterized in that the unit from 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 from the outside into this unit.

It is within the scope of the invention that, after the continuous filaments have been deposited on the depositing device or on the depositing screen, a thermal pre-consolidation of the fiber deposit or the nonwoven web can be carried out. For this purpose, according to the recommended embodiment of the invention, at least one thermal pre-consolidation device is provided. A recommended embodiment of the invention is characterized in that the at least one thermal pre-consolidation device is designed as a hot-air pre-consolidation device. The thermal pre-consolidation device expediently has at least one hot air knife and / or at least one hot air oven. According to another embodiment of the invention, thermal pre-consolidation or consolidation can also be carried out with pressure rollers or compacting rollers and / or at least one calender can be used for pre-consolidation or consolidation. According to a recommended embodiment of the device according to the invention, there is first a thermal pre-consolidation of the deposited nonwoven web with the help of at least one hot air knife, in particular with the help of a hot air knife, and then a further thermal pre-consolidation with the help of at least one hot air oven, in particular with the help of a hot air oven. A preferred embodiment of the invention is characterized in that the spunbond nonwoven is only pre-bonded with hot air and / or is only finally bonded with hot air. - The invention is based on the knowledge that due to the filament cross section according to the invention on the one hand the the entire filament circumference is available for thermal pre-consolidation and, on the other hand, through targeted selection of parameters - in particular the thickness of the jacket - the thermal pre-consolidation or the extent of thermal pre-consolidation can be specifically influenced, so that, on the one hand, an optimal consolidation of the nonwoven can be achieved and on the other hand, the crimp of the filaments is nevertheless not impaired too much in order to maintain a desired thickness of the nonwoven fabric. Within the scope of the invention, in particular due to the filament cross section according to the invention, a very simple and targeted setting of the nonwoven properties - in particular with regard to thickness, softness and strength - is possible. Above all, with the invention, the crimp can be easily adjusted and thus controlled.

The nonwovens according to the invention are distinguished 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 easily be kept within the desired limits due to the configuration of the filaments according to the invention, so that at the same time a controllable crimp or a controllable crimp is the result of the teaching according to the invention. With optimal strength and abrasion resistance that are easy to set, a largely defect-free nonwoven fabric can also be achieved which, above all, is essentially free of disruptive agglomerates. In summary, it can be stated that within the scope of the invention an optimal compromise between strength properties and thickness or softness properties of the nonwoven fabric can be achieved and this compromise can be achieved in a simple manner with a surprisingly homogeneous filament deposition.

Fig. 1

einen Querschnitt durch ein Endlosfilament

a)

mit herkömmlicher exzentrischer Kern-Mantel-Konfiguration und

b)

mit erfindungsgemäßer exzentrischer Kern-Mantel-Konfiguration,

Fig. 2

einen Schnitt durch ein erfindungsgemäßes Endlosfilament im Detail,

Fig. 3

schematisch die Abhängigkeit des Abstandes a der Flächenschwerpunkte von Kern und Mantel eines erfindungsgemäßen Endlosfilamentes von der Dicke d des Mantels der Endlosfilamente im Bereich der konstanten Dicke d des Mantels und

Fig. 4

einen Vertikalschnitt durch eine erfindungsgemäße Vorrichtung zur Erzeugung eines erfindungsgemäßen Spunbond-Vliesstoffes.

The invention is explained in more detail below with reference to a drawing showing only one embodiment. It shows in a schematic representation:

Fig. 1

a cross section through a continuous filament

a)

with conventional eccentric core-shell configuration and

b)

with an eccentric core-shell configuration according to the invention,

Fig. 2

a section through a continuous filament according to the invention in detail,

Fig. 3

schematically the dependence of the distance a of the centroids of the core and sheath of an endless filament according to the invention on the thickness d of the sheath of the continuous filaments in the region of the constant thickness d of the sheath and

Fig. 4

a vertical section through a device according to the invention for producing a spunbond nonwoven fabric according to the invention.

The Fig. 1 shows in comparison a section through a continuous filament 2 with a conventional eccentric core-sheath configuration ( Fig. 1a ) and by an endless filament 2 with an eccentric core-sheath configuration according to the invention ( Figure 1b ). In both cases it is Bicomponent filaments with a first component made of thermoplastic material in the sheath 3 and with a second component made of thermoplastic material in the core 4. Expediently, the component in the sheath 3 has a lower melting point than the component in the core 4. The Figure 1b as well as the Figure 2 Make it clear that in the case of the continuous filaments 2 for a spunbond nonwoven fabric 1 according to the invention, the sheath 3 of the filaments 2 preferably has a constant thickness d in the filament cross section and in the exemplary embodiment over more than 50% of the filament circumference. Preferably, and in the exemplary embodiment, the core 4 of the filaments 2 takes up more than 65% of the area of the filament cross section of the filaments 2.

Recommended and in the exemplary embodiment, the core 4 of the filaments 2 according to the invention - as seen in the filament cross section - is configured in the shape of a segment of a circle. Expediently and in the exemplary embodiment, the core 4 has an arcuate circumferential section 5 and a linear circumferential section 6 with respect to its circumference. As has been proven and in the exemplary embodiment, the circular arc-shaped circumferential section of the core 4 takes up over 65% of the circumference of the core 4. Expediently and in the exemplary embodiment, the jacket 3 of the filaments 2 - viewed in the filament cross section - is designed in the shape of a segment of a circle outside the jacket area with the constant thickness d. This circular segment 7 of the jacket 3 has, as recommended and in the exemplary embodiment with respect to its circumference, a circular arc-shaped circumferential section 8 and a linear circumferential section 9.

The thickness d or the mean thickness d of the jacket 3 is preferably 1% to 8%, in particular 2% to 10%, in the region of its constant thickness Filament diameter D. In the exemplary embodiment, the thickness d of the jacket 3 in the region of its constant thickness may be 0.2 to 3 μm.

The Fig. 2 shows the distance a of the centroid of the core 4 from the centroid of the sheath 3 of an endless filament 2 according to the invention. This distance a of the centroids of the core 4 and sheath 3 is at a given mass or area ratio of core and sheath material in the endless filaments 2 according to the invention regularly larger than with conventional continuous filaments 2 with an eccentric core-sheath configuration. The distance a of the centroid of the core 4 from the centroid of the sheath 3 in the filaments 2 according to the invention is preferably 5 to 40% of the filament diameter D or the largest filament diameter D. The Fig. 3 shows schematically for preferred embodiments of the invention the dependence of the distance a of the centroids of the core 4 and sheath 3 on the constant thickness d of the sheath 3 of the endless filaments 2 according to the invention. The dependence here is for an area proportion of the core 4 of 75%, of 67% and represented by 50%. The distance a and the constant jacket thickness d of the jacket 3 are each given in micrometers. The underlying endless filaments 2 according to the invention here have a filament diameter D of 18 μm.

The table below shows the distances a between the centers of area of core 4 and sheath 3 for continuous filaments 2 with a filament diameter D of 18 μm, specifically for different core: sheath ratios (75:25, 67:33 and 50:50). In the table on the left, these distances are listed for a constant sheath thickness d of 1 μm in the case of the continuous filaments according to the invention with an eccentric core-sheath configuration (eC / S filaments according to the invention). On the right in the table are the distances for a sheath thickness d 'of 1 μm at the point of the smallest distance between the core 4 and the outer surface for the continuous filaments 2 with a conventional eccentric core-sheath configuration (conventional eC / S filaments). The distance a between the centroids is listed here in absolute terms in µm and relative to the filament diameter D in%. Core: clad area ratio eC / S filaments according to the invention conventional eC / S filaments absolute (µm) relative to D (%) absolute (µm) relative to D (%) 75:25 1.5 8th 0.4 2 67:33 3.11 17th 1.1 6 50:50 4.1 23 2.5 14th

From the table it can be seen that the distance a of the centroids with the same filament diameter D and the same area ratio core: sheath in the endless filaments 2 according to the invention with an eccentric core-sheath configuration is greater or significantly greater than in the conventional continuous filaments 2 with an eccentric core Jacket configuration. Maintaining the distance a between the centers of area of the core 4 and cladding 3 is an essential feature of the invention which is of particular importance. The distance between the center of gravity is representative of the lever arm with which the crimping forces from the two materials act and thus a significant factor for the extent of the crimp.

Preferably, and in the exemplary embodiment, the core 4 of the filaments 2 according to the invention consists of polypropylene and the sheath 3 of the filaments 2 consists of polyethylene. This is a particularly preferred embodiment which has proven itself very well within the scope of the invention. It is fundamentally within the scope of the invention that the melting point of the thermoplastic material of the jacket 3 is lower than the melting point of the thermoplastic synthetic material of the core 4 of the continuous filaments 2 according to the invention.

According to a preferred embodiment of the invention, the continuous filaments 2 of a spunbond nonwoven fabric 1 according to the invention have a titer of 1.5 to 2.5 denier, preferably 1.5 to 2.2 denier and preferably 1.8 to 2.2 denier. This titer has proven to be particularly useful with regard to solving the technical problem. - It is also within the scope of the invention that the spunbond nonwoven 1 according to the invention is a thermally pre-bonded spunbond nonwoven, with thermal bonding points or bonding points between the continuous filaments 2. According to a particularly preferred embodiment, it is the spunbond nonwoven 1 according to the invention to a spunbond nonwoven which is thermally pre-bonded with hot air. Such a spunbond nonwoven 1 has proven itself very well with regard to solving the technical problem.

The Fig. 4 shows a device according to the invention for producing a spunbond nonwoven fabric 1 according to the invention, which consists in particular of crimped continuous filaments 2. The spunbond device comprises a spinneret 10 or a spinnerette for spinning the continuous filaments 2. The spinning nozzle 10 or the device is designed so that the continuous filaments 2 are produced as multicomponent filaments or bicomponent filaments with an eccentric core-sheath configuration preferably as continuous filaments 2, in which the sheath 3, viewed in the filament cross-section, has a constant thickness d over at least 50% of the filament circumference.

Preferably, and in the exemplary embodiment, the spun continuous filaments 2 are introduced into a cooling device 11 with a cooling chamber 12. Appropriately and in the 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 expediently introduced into the cooling chamber 12 from the air supply cabins 13, 14 arranged one above the other.

According to a preferred embodiment and in the embodiment according to Fig. 4 A monomer suction device 15 is arranged between the spinneret 10 and the cooling device 11. With 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.

A stretching device 16 for stretching the continuous filaments 2 is connected downstream of the cooling device 11 in the filament flow direction. Recommended and in the exemplary embodiment, the stretching device 16 has an intermediate channel 17 which connects the cooling device 11 to a stretching shaft 18 of the stretching device 16. According to a particularly preferred embodiment and in the 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 and apart from the supply of cooling air in the cooling device 11, there is no further air supply from the outside into this unit.

Recommended and in the exemplary embodiment, a diffuser 19, through which the continuous filaments 2 are guided, adjoins the stretching device 16 in the filament flow direction. After passing through the diffuser 19 are the endless filaments 2 are preferably deposited on a depositing device designed as a depositing screen belt 20 in the exemplary embodiment. The depositing screen belt 20 is preferred and, in the exemplary embodiment, is designed as an endlessly revolving depositing screen belt 20. It is expediently designed to be air-permeable, so that suction from below through the screen belt 20 is possible.

According to the recommended embodiment and in the exemplary embodiment, the diffuser 19 or the diffuser 19 arranged directly above the storage screen belt 20 has two opposite diffuser walls, two lower diverging diffuser wall sections 21, 22 being provided, which are preferably designed asymmetrically with respect to the center plane M of the diffuser 19. Expediently and in the exemplary embodiment, the inlet-side diffuser wall section 21 forms a smaller angle β with the center plane M of the diffuser 19 than the outlet-side diffuser wall section 22. This preferred embodiment is of particular importance within the scope of the invention and it has proven itself particularly with regard to solving the technical problem proven. The terms inlet side and outlet side relate here to the running direction of the depositing screen belt 20 or to the conveying direction of the nonwoven web.

According to a recommended embodiment of the invention, two opposite secondary air inlet gaps 24, 25 are provided at the inflow end 23 of the diffuser 19, each of which is arranged on one of the two opposite diffuser walls. A lower secondary air volume flow can preferably be introduced through the secondary air inlet gap 24 on the inlet side with respect to the conveying direction of the depositing screen belt 20 than through the secondary air inlet gap 25 on the outlet side this embodiment is of particular importance in the context of the invention.

Recommended and in the exemplary embodiment, at least one suction device is present with which air or process air can be sucked through the depositing screen belt 20 in a main suction area 27 in the deposit area 26 of the filaments 2. The main suction area 27 is expediently delimited below the depositing screen belt 20 in an inlet area of the depositing screen belt 20 and in an outlet area of the depositing screen belt 20 by a suction partition 28. Preferably and in the exemplary embodiment, the main suction area 27 is followed by a second suction area 29 in the conveying direction of the depositing screen belt 20, in which air or process air can be sucked through the depositing screen belt 20. It is recommended that the suction speed v _{2 of} the process air through the depositing screen belt 20 in the second suction area 29 is lower than the suction speed v _H in the main suction area 27.

A particularly preferred embodiment is characterized in that the end of a suction partition 28 facing the depositing screen belt 20 has a vertical distance A to the depositing screen belt 20 between 10 and 250 mm, in particular between 25 and 200 mm, preferably between 28 and 150 mm and preferably between 29 and 140 mm and very preferably between 30 and 120 mm. According to a highly recommended embodiment, in the area of this suction partition 28 facing the depositing screen belt 20, a partition wall section designed as a spoiler section 30 is connected, which includes said end of the suction partition 28 facing the depositing screen belt 20. It is within the scope of the invention that the end of this spoiler section 30 facing the depositing screen belt 20 becomes an imaginary extension of the remaining associated suction partition 28 horizontal distance C, which corresponds to at least 80% of the vertical distance A. The distances A and C are not shown in the figures. - According to one - in Fig. 4 As shown in the recommended embodiment shown, a suction partition wall 28 on the screen belt side has a partition wall section which is angled from the remaining suction partition wall 28 and is designed as a spoiler section 30. Expediently and in the 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 oriented perpendicular to the filing screen belt surface than a partition wall section of the further, opposite suction partition 28 facing the filing screen belt 20. Expediently, the spoiler section 30 has a greater length than the corresponding one in its projection onto the filing screen belt surface Projection of an angled or bent partition section of the further opposite suction partition 28 facing the depositing screen belt 20. It is recommended that the spoiler section 30 has a greater distance to the depositing screen belt 20 with respect to its end on the screen belt side than the end of the partitioning wall section of the further opposite suction partition 28 facing the depositing screen belt 20 The embodiment with the spoiler section 30 ensures a very even and continuous transition of the suction speeds from the house ptabsaugbereich 27 to the area following in the conveying direction of the depositing screen belt 20 and in particular to the second suction area 29. Due to the arrangement of the spoiler section 30, a very continuous steady decrease in the suction speed can be achieved. In this way, defects in the nonwoven web or in the spunbond nonwoven fabric 1 according to the invention can be largely avoided, which can occur due to abrupt changes in the suction speed, for example due to backflow effects (so-called blow-back effects) Transition area between the main suction area 27 and the second suction area 29. The embodiment with the spoiler section 30 is thus a very preferred embodiment which contributes to solving the technical problem of the invention.

Appropriately and in the exemplary embodiment, at least one thermal pre-consolidation device for thermal pre-consolidation of the nonwoven web is provided in the conveying direction of the nonwoven web after the depositing area 26. The thermal pre-consolidation device is preferably arranged on or above the second suction area 29. According to a particularly preferred embodiment, the thermal pre-consolidation device works with hot air and, particularly preferably, this thermal pre-consolidation device downstream of the main suction area 27 is a hot air knife 31. With the thermal pre-consolidation device, bonding points between the filaments 2 of the nonwoven web can be easily implemented. The jacket 3 of the continuous filaments 2 according to the invention, which runs around the entire circumference, can be used very effectively to form the thermal bonding points.

According to one embodiment of the invention, at least two thermal pre-consolidation devices are provided for pre-consolidation of the nonwoven web. The first thermal preconsolidation device in the conveying direction of the nonwoven web is expediently a hot air knife 31 and preferably a second thermal preconsolidation device in the form of a hot air oven 32 is connected downstream of this hot air knife 31 in the conveying direction of the depositing screen belt 20. It is within the scope of the invention that air is sucked through the sieve belt 20 in the area of the hot air oven 32 as well. Furthermore, it is within the scope of the invention that the suction speed of the air sucked off by the depositing screen belt 20 from Main suction area 27 decreases to further suction areas in the conveying direction of the depositing screen belt 20.

In Fig. 4 shows a spunbond device according to the invention with a spinneret 10 and thus with a spinning beam. It is also within the scope of the invention that a spunbond device according to the invention can be used in the context of a 2-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.

Claims (20)

Spunbond nonwoven fabric (1) made from continuous filaments (2), in particular from crimped continuous filaments (2), the filaments (2) being designed as bicomponent filaments or multicomponent filaments and having an eccentric core-sheath configuration and the sheath (3) of the Filaments (2) have a constant thickness d or an essentially constant thickness d in the filament cross-section over at least 20%, in particular over at least 25%, preferably over at least 30%, preferably over at least 35% and very preferably over at least 40% of the filament circumference . Spunbond nonwoven fabric according to one of claims 1 to 3, wherein the core (4) of the filaments (2) more than 50%, in particular more than 55%, preferably more than 60%, preferably more than 65% and very preferably more than 70 % of the area of the filament cross section of the filaments (2). Spunbond nonwoven fabric according to claim 1 or 2, wherein the core (4) of the filaments (2) is formed in the shape of a segment of a circle when viewed in the filament cross-section and has at least one, in particular a circular arc-shaped circumferential section (5) or substantially circular arc-shaped circumferential section (5) with respect to its circumference and has at least one, in particular a linear or essentially linear, circumferential section (6). Spunbond nonwoven fabric according to claim 3, wherein the circular arc-shaped circumferential section (5) of the core (4) occupies over 50%, in particular over 55%, preferably over 60% and preferably over 65% of the circumference of the core (4). Spunbond nonwoven fabric according to one of claims 1 to 4, wherein the sheath (3) of the filaments (2) - seen in the filament cross section - outside the Shell area with the constant thickness d is formed in the shape of a segment of a circle, this segment of a circle (7) having at least one, in particular a circular arc-shaped or essentially circular arc-shaped circumferential section (8) and at least one, in particular a linear or essentially linear circumferential section (9 ) having. Spunbond nonwoven fabric according to one of Claims 1 to 5, the sheath (3) of the filaments (2) - viewed in the filament cross section - having a constant thickness over 45%, in particular over 50%, preferably over 55% and preferably over 60% of the filament circumference d or a substantially constant thickness d. Spunbond nonwoven fabric according to one of claims 1 to 6, wherein the thickness of the sheath (3) in the region of its constant or substantially constant thickness d is less than 10%, in particular less than 8% and preferably less than 7% of the filament diameter D or . of the largest filament diameter D. Spunbond nonwoven fabric according to one of claims 1 to 7, wherein the thickness of the jacket (3) in the range of its constant or substantially constant thickness d 0.1 to 5 µm, in particular 0.1 to 4 µm, preferably 0.1 to 3 µm, preferably 0.1 to 2 µm and very preferably 0.1 to 0.9 µm. Spunbond nonwoven fabric according to one of claims 1 to 8, wherein the ratio of the mass of the core (4) to the mass of the jacket (3) 90:10 to 50:50, preferably 90:10 to 60:40 and preferably 85:15 to 70:30 is. Spunbond nonwoven fabric according to one of Claims 1 to 9, the distance a of the centroid of the core (4) from the centroid of the Sheath (3) 5% to 45%, in particular 6% to 40% and preferably 6% to 36% of the filament diameter D or the largest filament diameter D. Spunbond nonwoven fabric according to claim 10, wherein the distance a of the centroids is between 5% and 45% of the filament diameter D or the largest filament diameter D at a core: sheath mass ratio of 85:15 to 70:30 and / or at a core mass ratio : Sheath from 70:30 to 60:40 between 12% and 40% of the filament diameter or the largest filament diameter D and / or with a core: sheath mass ratio of 60:40 to 45:55 between 18% and 36% of the filament diameter D or the largest filament diameter D is. Spunbond nonwoven fabric according to one of claims 1 to 11, wherein the core (4) and / or the sheath (3) of the filaments (2) consists or essentially consists of at least one polyolefin, in particular both the core (4) and the sheath (3) of the filaments (2) also consists or essentially consists of at least one polyolefin and wherein preferably the sheath (3) consists or essentially consists of polyethylene and wherein preferably the core (4) consists of polypropylene or im Consists essentially of polypropylene. Spunbond nonwoven fabric according to one of claims 1 to 12, 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, wherein in particular the core ( 4) consists of or essentially consists of a polyester, and preferably the jacket (3) consists or essentially consists of a copolyester. Spunbond nonwoven fabric according to one of Claims 1 to 13, the titer of the filaments being 1.5 to 2.5 denier, in particular 1.7 to 2.3 denier, preferably 1.8 to 2.2 denier. Spunbond nonwoven according to one of claims 1 to 14, wherein the nonwoven (1) is a thermally pre-bonded and / or thermally bonded nonwoven (1) which has bonding points or bonding points between the filaments. Device for producing a spunbond nonwoven fabric (1) from continuous filaments (2), in particular from crimped continuous filaments (2), at least one spinneret (10) being present, the device or the spinneret (10) being set up with the proviso that multicomponent filaments or bicomponent filaments with an eccentric core-sheath configuration can be produced, the sheath (3) of the filaments (2) seen in the filament cross-section over at least 20%, in particular over at least 25%, preferably over at least 30%, preferably over at least 35 % and very preferably over at least 40% of the filament circumference has a constant thickness d or substantially constant thickness d and wherein the filaments (2) can be deposited on a depositing device, in particular on a depositing screen belt (20). Apparatus according to claim 16, wherein the apparatus has a cooling device (11) for cooling the filaments (2) and an adjoining stretching device (16) for stretching the filaments (2) and preferably at least one diffuser (19) adjoining the stretching device (16) ) having. Apparatus according to claim 17, wherein the unit of cooling device (11) and stretching device (16) is designed as a closed unit and wherein apart from the supply of cooling air in the cooling device (11) no further air supply takes place from outside. Apparatus according to one of claims 16 to 18, wherein at least one thermal pre-consolidation device is provided with which the nonwoven web (1) made of the filaments (2) deposited on the depositing device or on the depositing screen belt (20) can be thermally pre-consolidated. Apparatus according to claim 19, wherein the thermal pre-consolidation device is designed as a hot-air pre-consolidation device.

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