EP3771763A1 - Device and method for producing nonwoven fabric from crimped fibers - Google Patents

Abstract

Apparatus for producing a nonwoven fabric from crimped continuous filaments, with at least one spinning device being provided for spinning the filaments and with an air-permeable depositing conveyor for depositing the fibers in a depositing area. At least one first pre-consolidation device is arranged behind the deposit area in the conveying direction of the nonwoven web. A suction device is provided with which process air can be sucked in by the deposit conveyor in the deposit area of the fibers and / or in the area of the first pre-consolidation device. A second pre-consolidation device is connected downstream of the first pre-consolidation device in the conveying direction, process air being able to be sucked through the deposit conveyor in the area of the second pre-consolidation device. In the area between the first pre-consolidation device and the second pre-consolidation device, a suction gap section is arranged, with no suction of process air taking place in the suction gap section and / or wherein the suction gap section is set up with the proviso that there is less suction of process air there than in the storage area of the fibers and / or in the area of the first pre-consolidation device and / or that there is less suction of process air there than in the area of the second pre-consolidation device.

Description

The invention relates to a device for producing a nonwoven fabric from crimped fibers, in particular from crimped endless filaments, with at least one spinning device or at least one spinning beam being provided for spinning the fibers and with an air-permeable depositing conveyor, in particular a depositing screen belt for depositing the fibers or the continuous filaments is present in a storage area to a nonwoven web. The invention also relates to a method for producing a nonwoven fabric. According to a very preferred embodiment of the invention, the fibers forming the nonwoven are continuous filaments. Due to their quasi-endless length, continuous filaments differ from staple fibers, which have significantly shorter lengths of e.g. 10 mm to 60 mm. The nonwoven fabric produced according to the invention is preferably composed of such continuous filaments. The device according to the invention is particularly preferably a spunbond device, the method according to the invention is a spunbond method and the nonwoven fabric produced is a spunbond nonwoven fabric.

Devices and methods of the type mentioned are known from practice and from the prior art in various embodiments. For many applications, nonwovens with a large thickness and a high softness are required. These are so-called high-loft products or high-loft nonwovens. A high thickness of a nonwoven fabric is normally achieved when crimped filaments are used. For this purpose, multicomponent filaments or bicomponent filaments with a side-by-side configuration or with an eccentric core-sheath configuration are mainly used. Achieving a great Thickness and a high softness are often associated with a relatively low strength of the nonwoven fabric. This applies both to the tensile strength of the nonwoven in the machine direction (MD) and to the abrasion resistance of the nonwoven surface. Increases in thickness and / or in softness are generally at the expense of strength, and conversely, increases in strength due to solidification of the nonwoven fabric lead to a reduction in the thickness and / or to a reduction in the softness of the nonwovens. As a result, there is a conflict of objectives when producing high-loft products.

In particular when producing high-loft nonwovens, another problem is that the laid down nonwoven webs often do not have the desired homogeneity, particularly with regard to their surface. Defects can often be found in the fleece or fleece surface. Such defects are mainly caused by backflow effects (so-called blow-back effects). When the nonwoven web deposited on the delivery conveyor passes from a more vacuumed area of the delivery conveyor to a less vacuumed area of the delivery conveyor, filaments or nonwoven components are pulled back from the less vacuumed area into the more vacuumed area (blow-back effect). This results in disruptive defects or filament agglomerates in the nonwoven web or in the nonwoven web surface. In this respect there is a need for improvement.

The invention is based on the technical problem of specifying a device for producing a nonwoven fabric from crimped fibers of the type mentioned, with which a nonwoven fabric of high thickness and high softness can be produced, but which is nevertheless also characterized by satisfactory strength and abrasion resistance and which is still defect-free and in particular free from agglomerates. also the invention is based on the technical problem of specifying a corresponding method for producing a nonwoven fabric.

To solve the technical problem, the invention teaches a device for producing a nonwoven fabric from crimped fibers, in particular from crimped endless filaments, at least one spinning device or at least one spinning beam for spinning the fibers or continuous filaments being provided, with an air-permeable depositing conveyor, in particular a depositing screen belt to deposit the fibers in a deposit area to form a nonwoven web,
At least one first pre-consolidation device for pre-consolidation of the non-woven web is arranged in the conveying direction of the nonwoven web behind the deposit area of the fibers, with at least one suction device being provided, with the air or process air in the deposit area of the fibers and / or in the area of the first pre-consolidation device by the deposit conveyor or can be sucked through the filing belt,
wherein at least one second pre-consolidation device for pre-consolidation of the nonwoven web is connected downstream of the first pre-consolidation device in the conveying direction of the nonwoven web, wherein in the area of the second pre-consolidation device air or process air can be sucked through the deposit conveyor or through the deposit screen belt
and wherein a suction gap section is arranged in the area between the first pre-consolidation device and the second pre-consolidation device, with no suction of air or process air taking place in the suction gap section by the depositing conveyor or by the depositing screen belt and / or wherein the suction gap section is set up with the proviso that there one Less or significantly less suction of air or process air takes place than in the storage area of the fibers and / or in the area of the first pre-consolidation device and / or that there is less suction of air or process air than in the region of the second pre-consolidation device.

It is within the scope of the invention that the device according to the invention is used as a beam component in a two-bar system or multi-bar system. A plurality of bars or bar components of the two-bar system or multi-bar system can also be designed in the form of a device according to the invention according to patent claim 1. To this extent, within the scope of the invention, only one nonwoven web or a laminate can be produced from several nonwoven webs arranged one above the other.

The depositing conveyor or the depositing screen belt is preferably designed as an endlessly rotating depositing conveyor or as an endlessly rotating depositing screen belt. It is essential within the scope of the invention that the at least two preconsolidations and the arrangement of the suction gap section take place on one and the same deposit conveyor or deposit screen belt.

According to the invention, crimped or crimped fibers are produced, and in particular crimped or crimped continuous filaments. In the context of the invention, crimp means in particular that the crimped fibers or 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 . According to a particularly recommended embodiment, the crimped fibers or filaments each have a crimp of 1.5 to 3.5 and preferably of 2 to 3 Loops per centimeter of their length. The number of crimped loops or crimped arcs (loops) per centimeter of length of the fibers / filaments is measured in particular according to the Japanese standard JIS L-1015-1981 by applying the crimps under a pretension of 2 mg / den in (1/10 mm) are counted based on the unstretched length (crimped 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. To this end, reference is made to the publication "Automatic Crimp Measurement on Staple Fibers", Denkendorf Colloqium, "Textile Mess- und Prüftechnik", November 9, 1999, Dr. Ulrich Mörschel (in particular page 4, Fig. 4) referred. For this purpose, the filaments or the filament sample are / will be removed from the deposit or from the depositing screen belt as a filament ball before further solidification and the filaments are separated and measured.

It is within the scope of the invention that bicomponent fibers or multicomponent fibers and in particular bicomponent filaments or multicomponent filaments are used to produce the crimped fibers or filaments. It is expedient to use bicomponent filaments or multicomponent filaments with an eccentric core-sheath configuration or with a side-by-side configuration. Fibers or continuous filaments with an eccentric core-sheath configuration are preferred. The last-mentioned fibers have proven particularly useful for the device according to the invention and for the method according to the invention. A very preferred embodiment of continuous filaments with an eccentric core-sheath configuration used in the context of the invention is explained in more detail below.

It is within the scope of the invention that the device according to the invention is a spunbond device. According to the invention, the fibers or continuous filaments are spun with a spinning device. Appropriately downstream of the spinning device in the direction of flow of the fibers is at least one cooling device for cooling the fibers and at least one stretching device connected to the cooling device for stretching the fibers. Advantageously, at least one diffuser adjoins the stretching device in the flow direction of the fibers. A highly recommended 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 outside air is fed into this unit. The fibers / filaments leaving the diffuser are expediently deposited directly on the depositing conveyor or on the depositing screen belt.

A particularly preferred embodiment of the invention is characterized in that a diffuser arranged directly above the depositing conveyor or above the depositing screen belt has two opposite diffuser walls, two lower diverging diffuser wall sections being provided. The two lower diverging diffuser wall sections of the diffuser are preferably arranged asymmetrically with respect to the center plane M of the diffuser or of the device. It is recommended that the diffuser wall section on the inlet side with respect to the depositing conveyor encloses a smaller angle β with the center plane M of the diffuser than the diffuser wall section on the outlet side. Appropriately, the angle β - which the inlet-side diffuser wall section encloses with the central plane M - is at least 1 ° less than the corresponding angle which the outlet-side diffuser wall section encloses with the central plane M. - The terms The inlet side and the outlet side relate here in particular to the conveying direction or the running direction of the deposit conveyor or the depositing screen belt. The asymmetrical configuration of the diffuser with respect to the center plane M of the device has proven particularly useful in terms of solving the technical problem according to the invention. It is within the scope of the invention that the ends of the diverging diffuser wall sections on the storage conveyor side have a different distance e from the center plane M of the device. Preferably, the distance e _{1 of} the conveyor-side end of the inlet-side diffuser wall section is less than the distance e _{2 of} the conveyor-side end of the outlet-side diffuser wall section from the center plane M of the device. The ratio of the distances e ₁ : e ₂ is expediently 0.6 to 0.95, preferably 0.65 to 0.9 and in particular 0.7 to 0.9.

A particularly preferred embodiment of the invention is further characterized in that the diffuser arranged directly above the deposit conveyor or above the deposit screen belt has two opposite diffuser walls, with at least two opposite secondary air inlet gaps being provided at the inflow end of the diffuser, each at one of the two opposite Diffuser walls are arranged. The inflowing end of the diffuser means the end of the diffuser into which the drawn fibers or filaments enter. Preferably, a lower secondary air volume flow can be introduced through the secondary air inlet gap on the inlet side with respect to the conveying direction of the depositing conveyor than through the secondary air inlet gap on the outlet side. According to one embodiment of the device according to the invention, the inlet-side secondary air inlet gap is designed narrower in the machine direction (MD) than the outlet-side secondary air inlet gap. - Machine direction (MD) means in the context of the invention in particular the conveying direction of the depositing conveyor or the Filing screen belt and thus the conveying direction of the nonwoven web. It is within the scope of the invention that the width of the inlet-side secondary air inlet gap and / or the width of the outlet-side secondary air inlet gap is adjustable. It is recommended that the secondary air volume flow of the inlet-side secondary air inlet gap is at least 5%, preferably at least 10% and in particular at least 15% less than the secondary air volume flow through the outlet-side secondary air inlet gap.

The spun, cooled and drawn fibers or filaments are deposited in a deposit area of the deposit conveyor or the depositing screen belt for the nonwoven web. It is within the scope of the invention that process air is sucked in from below through the storage conveyor or through the storage screen belt in a main suction area under this storage area of the fibers / filaments. The extraction of the process air in this main extraction area takes place at the extraction speed v _H. The main suction area is expediently delimited by an inlet-side suction partition and an outlet-side suction partition. It is within the scope of the invention that in a second suction area downstream of the main suction area in the machine direction (MD), process air is also sucked through the deposit conveyor or through the depositing screen belt, namely at a suction speed v ₂ . Furthermore, it is within the scope of the invention that the suction speed v _H in the main suction area is greater or significantly greater than the suction speed v ₂ in the second suction area. A particularly preferred embodiment of the invention is characterized in that the outlet-side suction partition between the main suction area and the second suction area has a storage conveyor-side end which is arranged at a vertical distance A from the storage conveyor. This vertical distance A is expediently 10 mm to 250 mm, in particular 25 mm to 200 mm, preferably 28 mm to 150 mm, preferably 29 mm to 120 mm, very preferably 30 mm to 120 mm and recommended 35 mm to 120 mm. In this context, a well-proven embodiment is characterized in that the outlet-side suction partition wall comprises, at its end on the conveyor side, a partition wall section which is angled from the rest of the suction partition wall and is designed as a spoiler section. In this case, the end of this spoiler section on the conveyor side expediently maintains the vertical distance A from the deposit conveyor or from the deposit screen belt. The realization of the relatively large distance A between the conveyor-side end of the outlet-side suction partition and the storage conveyor or between the conveyor-side end of the spoiler section and the storage conveyor brings very special advantages within the scope of the invention. This configuration enables a continuous or linearly steady transition of the suction speed from the main suction area with the high suction speed v _H to the second suction area with the lower or significantly lower suction speed v ₂ . In this way, disadvantageous blow-back effects at the end of the main suction area in particular are avoided and nonwoven webs with a very homogeneous and defect-free surface can be produced. The implementation of the vertical distance A or the implementation of the preferred spoiler section has proven particularly useful in the context of the invention.

According to the invention, at least one first pre-consolidation device for the pre-consolidation of the nonwoven web is arranged in the conveying direction behind the deposit area of the fibers. This first pre-consolidation device is expediently arranged in the area of the second suction area or above the second suction area. It is within the scope of the invention that the at least one first pre-consolidation device is a hot-air pre-consolidation device. According to a recommended embodiment, there is only a first pre-consolidation device or only a first Hot air pre-consolidation device is provided between the fiber deposit area and the suction gap section. According to a particularly preferred embodiment of the invention, the at least one first hot air pre-consolidation device is designed as a hot air knife. A proven embodiment of the invention is characterized in that only one hot air pre-consolidation device, in particular in the form of a hot air knife, is arranged between the storage area of the fibers and the suction gap section. It could also be a hot air oven.

According to the invention, the suction gap section is arranged in the area between the first pre-consolidation device and the second pre-consolidation device. This suction gap section is described or specified in more detail below. The at least one first pre-consolidation device and the suction gap section are followed by at least one second pre-consolidation device for pre-consolidation of the nonwoven web in the conveying direction of the nonwoven web. The at least one second pre-consolidation device is preferably a hot air pre-consolidation device. According to a particularly recommended embodiment of the invention, this at least one second hot air pre-consolidation device is a hot air oven. A tried and tested embodiment is characterized in that this hot air oven is operated as part of a circulatory system and that the mass flow supplied as hot air and the extracted mass flow are preferably the same or are approximately the same. It is within the scope of the invention that the mass flow sucked off by the deposit conveyor is somewhat greater than the hot air mass flow supplied. In this context, somewhat larger means that the difference can be up to a maximum of 25%, preferably up to a maximum of 10% of the mass flow supplied. In this connection, it is recommended that the device is adjusted with the proviso that the entry of the nonwoven web into the area of the second Hot air pre-consolidation device is supported by a rectified air flow. In addition, vapors from the nonwoven fabric can be removed from the circulating air in this way. Furthermore, it is within the scope of the invention that after the second pre-consolidation device or after the second hot-air pre-consolidation device, a cooling zone is provided on the deposit conveyor or on the deposit screen belt in order to stabilize the nonwoven fabric.

One embodiment is characterized in that only a second pre-consolidation device or only a second hot-air pre-consolidation device and preferably only a hot air oven for pre-consolidation of the nonwoven web is connected downstream of the suction gap section according to the invention. It is also within the scope of the invention that below the second pre-consolidation device or below the second hot-air pre-consolidation device, process air is sucked through the deposit conveyor or through the depositing screen belt, specifically in a third suction area with suction speed v ₃ .

According to a particularly preferred embodiment of the invention, the suction speed v _H in the main suction area is greater than the suction speed v ₂ in the second suction area and the suction speed v _{2 of} the second suction area is expediently greater than the suction speed v _{3 of} the third suction area. It is recommended that the suction speed v _{2 of} the second suction area - in particular below the first pre-consolidation device - is 15% to 50%, in particular 25% to 40% and preferably 27% to 35% of the suction speed v _{H of} the main suction area. Furthermore, it is preferred within the scope of the invention that the suction speed v ₃ in the third suction area - preferably below the second pre-consolidation device - 5% to 30%, in particular 7% to 25% and preferably 7% to 12% of the suction speed v _{H of} the main suction area. It is within the scope of the invention that the suction speed v _{3 of} the third suction area is less than the suction speed v _{2 of} the second suction area.

In the suction gap section arranged between the at least one first pre-consolidation device and the at least one second pre-consolidation device, according to a preferred embodiment of the invention, no suction takes place, so that the suction speed v _{L is} equal to zero. According to another embodiment of the invention, slight suction takes place in the suction gap section, preferably at a suction speed v _L that is lower than the suction speed v _{2 of} the second suction area and preferably also smaller than the suction speed v _{3 of} the third suction area. The length L of the suction gap section according to the invention in the machine direction (MD) or in the conveying direction of the storage conveyor is expediently greater than the length of the storage area for the fibers or filaments in the machine direction (MD) or in the conveying direction of the storage conveyor. In the context of the invention, it has been proven that the length L of the suction gap section is greater than the width range in the machine direction (MD) in which a hot air knife used as the first hot air pre-consolidation device applies hot air to the nonwoven web. A particularly preferred embodiment of the invention is characterized in that the length L of the suction gap section in the machine direction (MD) is 300 mm to 5,000 mm, in particular 1,000 mm to 4,500 mm and preferably 1,200 mm to 4,000 mm. It is within the scope of the invention that the length L of the suction gap section is at least 30%, preferably at least 35%, preferably at least 40%, very preferably at least 45% and in particular at least 50% of the Distance C between the last first preconsolidation device in the conveying direction and the second preconsolidation device immediately following in the conveying direction is. It is within the scope of the invention that the distance C is 400 mm to 5,200 mm, in particular 1,100 mm to 4,700 mm and preferably 1,300 mm to 4,200 mm.

A preferred embodiment of the invention is characterized in that, given a low level of suction in the suction gap section according to the invention, the suction speed v _{L is} only 1% to 15%, preferably 1.2% to 10%, preferably 1.4% to 8%, very preferably 1 , 5% to 5%, particularly preferably 1.6% to 4% and in particular 1.7% to 3% of the main suction speed v _H in the main suction area. According to a highly recommended embodiment of the invention, the suction speed v _{L is} adjustable in the suction gap section. It is also within the scope of the invention that with little suction in the suction gap section the suction speed v _{L is} only 2% to 45%, preferably 2.4% to 30% and very preferably 2.8% to 16% and in particular 3.4% to 9% of the suction speed v ₂ in the second suction area. It has also proven that the suction speed v _L in the suction gap section is less than the suction speed v ₃ in the third suction area and that the suction speed v _{L is} a maximum of 50%, preferably a maximum of 45%, preferably a maximum of 40% and particularly preferably a maximum of 30% of the suction speed v ₃ in the third suction area. In principle, according to another embodiment of the invention, the suction speed v _L in the suction gap section can also be greater or somewhat greater than the suction speed v ₃ in the third suction area.

The invention is based on the knowledge that the implementation of a suction gap section according to the invention involves the production of nonwovens high thickness and / or high softness significantly simplified. Furthermore, the invention is based on the knowledge that the nonwoven from the crimped or crimped fibers can relax in the suction gap section, as it were, before further pre-consolidation, and due to the fact that there is no or only a very low hold-down force on the nonwoven here, the nonwoven can develop sufficient thickness. In this way, a high thickness and great softness of the nonwoven fabric can be ensured in an advantageous manner and nevertheless sufficient strength of the nonwoven fabric can be achieved by the pre-consolidations arranged according to the invention. In this respect, the suction gap section according to the invention has considerable advantages.

In addition to the advantages explained above, the suction gap section according to the invention also brings about further advantages. It is within the scope of the invention that at least one third pre-consolidation device for the nonwoven can be introduced into the suction gap section and can expediently be positioned on the deposit conveyor or on the deposit screen belt. It is particularly preferred that this third pre-consolidation device can be removed or removed again from the suction gap section or from the depositing conveyor as required. According to a very preferred embodiment of the invention, the third pre-consolidation device is at least one roller or roller and is recommended to be a roller pair or roller pair. The roller or roller, and preferably the roller pair or roller pair, is expediently pivoted into the suction gap section if necessary and preferably also removed or pivoted out of the suction gap section again if necessary. Preferably, when the roller pair or roller pair is pivoted in, a roller or a roller is pivoted from below onto the storage conveyor and a roller or a roller is pivoted from above onto the storage conveyor. The role or the pair of roles is after Proven embodiment of the invention to a compacting roller or a pair of compacting rollers for compacting the nonwoven web on the delivery conveyor. The invention is based on the knowledge that the suction gap section according to the invention not only brings considerable advantages with regard to the quality of the nonwoven web or with regard to a high-loft product to be produced, but can also be used for an additional pre-consolidation device.

The at least one roller or cylinder that can be pivoted into the suction gap section or onto the depositing conveyor expediently has a diameter Z of 200 mm to 500 mm and in particular 250 mm to 450 mm. A roller or roller pivoted from above into the suction gap section between the first pre-consolidation device and the second pre-consolidation device has a distance or horizontal distance X of 50 mm to 800 mm, in particular of 60 mm to 700 mm, with respect to the first pre-consolidation device upstream in the machine direction, expediently from 70 mm to 600 mm and preferably from 100 mm to 500 mm. It is also within the scope of the invention that this roller or roller pivoted from above into the suction gap section between the two pre-consolidation devices has a distance Y or horizontal distance Y to the second pre-consolidation device downstream in the machine direction of 50 mm to 1,500 mm, in particular 60 mm to 1,250 mm and preferably from 100 mm to 1,000 mm.

It is within the scope of the invention that a swiveling out of the roller or roller is combined with a transfer of the roller or roller to a - preferably vertical - distance of at least 20 mm, expediently of at least 150 mm, to the depositing conveyor. According to another embodiment of the invention, the roller or roller can also extend sideways are driven in the area of the storage conveyor and are then located next to the device in a parking position.

The suction gap section according to the invention is followed by at least one second pre-consolidation device in the machine direction (MD) or in the conveying direction of the depositing conveyor, which is expediently designed as a hot air pre-consolidation device and is preferably designed as a hot air oven and in particular as just a hot air oven. According to one embodiment of the invention, the width range in the machine direction (MD) in which the hot air oven applies hot air to the nonwoven web is larger or longer than the suction gap section and, according to an embodiment variant, also longer than the distance C between the first pre-consolidation device and the second pre-consolidation device .

According to a particularly preferred embodiment of the invention, a hot air knife is used as at least one first hot air pre-consolidation device or as first hot air pre-consolidation device. A recommended embodiment is characterized in that the hot air knife applies hot air to the nonwoven web over a width range in the machine direction (MD) of 15 mm to 300 mm, in particular from 30 mm to 250 mm and preferably from 40 mm to 200 mm. The distance between the at least one hot air nozzle of the hot air knife and the surface of the storage conveyor or the surface of the storage screen belt is expediently 2 mm to 200 mm, preferably 2 mm to 150 mm and in particular 3 mm to 100 mm. It is within the scope of the invention that the nonwoven web is pre-consolidated by means of the hot air knife by hot air with a hot air temperature of 80 ° C to 250 ° C, in particular from 100 ° C to 200 ° C and preferably from 120 ° C to 190 ° C. It is recommended that the hot air has a speed of 1.9 during hot air pre-consolidation with the hot air knife to 8 m / s, in particular from 2 to 6 m / s and preferably from 2.2 to 5.5 m / s.

According to a preferred embodiment of the invention, a hot air oven is used as at least one second hot air pre-consolidation device or as a second hot air pre-consolidation device. According to a proven embodiment of the invention, the hot air oven applies hot air to the nonwoven web over a width range in the machine direction (MD) from 280 mm to 2,000 mm, in particular from 290 mm to 1,800 mm and preferably from 300 mm to 1,500 mm. The hot air outlet openings of the hot air oven are recommended to have a distance of 12 mm to 200 mm, in particular from 20 mm to 150 mm and preferably from 25 mm to 120 mm from the surface of the storage conveyor or from the surface of the storage screen belt. It is recommended that the hot air pre-consolidation is carried out with hot air in the hot air oven at a hot air temperature of 110 ° C to 180 ° C, in particular from 115 ° C to 170 ° C and preferably from 120 ° C to 160 ° C. It is recommended that the hot air has a speed of 1 to 2 m / s, in particular of 1.1 to 1.9 m / s and preferably of 1.2 to 1.8 m / s, during the hot air pre-consolidation with the hot air oven.

It is within the scope of the invention that bicomponent filaments or multicomponent filaments are used to produce the crimped filaments or fibers. Bicomponent filaments or multicomponent filaments with an eccentric core-sheath configuration are particularly preferred. Bicomponent filaments or multicomponent filaments with an eccentric core-sheath configuration, in which the sheath 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% as well as special preferably has a constant thickness d or an essentially constant thickness d over at least 45% of the filament circumference. It is recommended that the sheath of the filaments have the constant thickness d or the essentially constant thickness d over at least 50%, preferably over at least 55% and preferably over at least 60% of the filament circumference. With these filaments, the core expediently takes up more than 50%, in particular more than 55%, preferably more than 60%, preferably more than 65% of the area of the filament cross section of the filaments in relation to the filament cross section. The core of these filaments, viewed in the filament cross-section, is recommended to be formed in the shape of a segment of a circle and, with respect to its circumference, has an arcuate or an essentially arcuate circumferential section and a linear or essentially linear circumferential section. Furthermore, it is preferred with these filaments that the sheath of the filaments - seen in the filament cross section - is formed in the shape of a segment of a circle outside the sheath area with the constant thickness d, this segment of a circle having an arcuate or essentially arcuate circumferential section with respect to its circumference and a linear or in Essentially linear circumferential section. According to a highly recommended embodiment, the thickness of the sheath of these preferred filaments in the region of the constant thickness d or the substantially constant thickness d of the sheath is less than 10%, in particular less than 8% and preferably less than 7% of the filament diameter D or des largest filament diameter D. It is also within the scope of the invention that with these preferred filaments, 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% up to 34% of the filament diameter D or the largest filament diameter D.

A particularly recommended embodiment of the invention is characterized in that the fibers or filaments produced according to the invention consist or essentially consist of at least one polyolefin. With regard to the preferably used bicomponent filaments or multicomponent filaments with an eccentric core-sheath configuration, there is preferably at least one component or both or all components consist of at least one polyolefin or essentially of at least one polyolefin. In the case of the filaments with an eccentric core-sheath configuration, at least the sheath preferably consists of at least one polyolefin or essentially of at least one polyolefin. According to a well-proven embodiment, the jacket consists of polyethylene or essentially of polyethylene and the core preferably consists of polypropylene or essentially of polypropylene. According to another recommended embodiment, the core consists of at least one polyester or essentially of at least one polyester and the jacket consists of at least one polyolefin or essentially of at least one polyolefin. Polyethylene terephthalate (PET) is preferably used as the polyester in the context of the invention. In a proven variant, the core consists of PET or essentially of PET and the jacket preferably consists of a polyolefin, in particular of polyethylene or essentially of polyethylene. Another embodiment is characterized in that the core consists or substantially consists of at least one polyester and that the jacket consists or substantially consists of at least one copolyester. - It is within the scope of the invention that the plastic component of the jacket has a lower melting point than the plastic component of the core. In the context of the invention, bicomponent filaments or multicomponent filaments with an eccentric core-sheath configuration have proven their worth Sheath made of polyethylene or essentially consists of polyethylene and the core of which consists of polypropylene or essentially of polypropylene.

A preferred embodiment of the invention is characterized in that the components of the continuous filaments used in the context of the invention or, in the case of continuous filaments with an eccentric core-sheath configuration, the core and / or the sheath are made from at least one polymer from the group "polyolefin, polyolefin copolymer , in particular polyethylene, polypropylene, polyethylene copolymer, polypropylene copolymer; polyester, polyester copolymer, especially polyethylene terephthalate (PET), PET copolymer, polybutylene terephthalate (PBT), PBT copolymer, polylactide (PLA), PLA copolymer "consists / exist or essentially exist / exist. It is also within the scope of the invention to use mixtures or blends of the aforementioned polymers for the components or for the core and / or for the shell. It is within the scope of the invention that the plastic used for the jacket has a lower melting point than the plastic used for the core.

In the context of the method according to the invention, a production speed of at least 250 m / min, in particular at least 300 m / min, is preferably used. The process according to the invention expediently produces nonwovens with a weight per unit area of 12 to 50 g / m ² , preferably 20 to 40 g / m ² .

It is within the scope of the invention that the titer of the filaments used for the nonwoven web is between 1 den and 12 den. According to a highly 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. Especially filaments with a denier of 1.5 denier to 2.2 denier and preferably from 1.8 denier to 2.2 denier have proven particularly useful in the context of the invention.

To solve the technical problem, the invention also teaches a method for producing a nonwoven fabric from crimped fibers, in particular from crimped continuous filaments, the fibers or filaments being spun and deposited on an air-permeable storage conveyor or storage screen belt,
wherein in the storage area of the fibers air or process air is sucked in a main suction area through the storage conveyor or through the storage screen belt and wherein in the machine direction (MD) behind the storage area the fibers are preconsolidated in at least one preconsolidation stage on the storage conveyor, in the area of the first preconsolidation stage Air or process air is sucked through the delivery conveyor in a second extraction area,
wherein the fibers are pre-consolidated in at least one of the second pre-consolidation stage downstream of the first pre-consolidation stage in the machine direction (MD) on the delivery conveyor, with air or process air being sucked through the delivery conveyor in the area of the second pre-consolidation stage in a third suction area
and wherein in the area between the first pre-consolidation stage and the second pre-consolidation stage, at least one suction gap section is arranged in which no air or process air is sucked through the delivery conveyor and / or in which less or significantly less suction of air or process air is carried out than in the second suction area and / or in the third suction area.

The invention is based on the knowledge that with the device according to the invention and with the method according to the invention, nonwovens with optimal properties and in particular with optimal surface properties can be produced. In particular, high-loft nonwovens with great thickness and high softness can be produced without any problems and these nonwovens are nonetheless characterized by a completely satisfactory strength in the machine direction (MD) and also by a completely adequate abrasion resistance. The invention is based in particular on the knowledge that with the aid of the suction gap section according to the invention between the first pre-consolidation device and the second pre-consolidation device, the high-loft properties - in particular high thickness and high softness - can be optimally stabilized. The suction gap section contributes, as it were, to the fact that the nonwoven web can relax in thickness in this section or that the nonwoven thickness can stabilize here outstandingly. With the upstream and downstream pre-consolidation devices, an optimal strength can be set at the same time. The desired properties of the nonwoven can be set in a targeted, reliable and reproducible manner. In the context of the device according to the invention and the method according to the invention, it is also of particular advantage that the nonwoven webs or nonwovens produced can be produced virtually without defects and above all do not have any disruptive inhomogeneities in their surface structure. With the measures according to the invention, above all disadvantageous filament agglomerates in the nonwoven web surface or in the nonwoven web surface can be avoided. It should be emphasized that the aforementioned considerable advantages can be achieved in a relatively simple and inexpensive manner.

Fig. 1

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

Fig. 2

den Gegenstand nach Fig. 1 detaillierter im Bereich des Ablageförderers und im Bereich der Vorverfestigungseinrichtungen und

Fig. 3

einen Schnitt durch ein bevorzugt im Rahmen der Erfindung eingesetztes Endlosfilament mit exzentrischer Kern-Mantel-Konfiguration.

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

Fig. 2

the subject Fig. 1 in more detail in the area of the storage conveyor and in the area of the pre-consolidation devices and

Fig. 3

a section through an endless filament with an eccentric core-sheath configuration, preferably used in the context of the invention.

In the Fig. 1 a device according to the invention for producing a nonwoven fabric 1 from continuous filaments 2 made of thermoplastic material is shown. This device is a spunbond device for producing a spunbond nonwoven fabric from continuous filaments 2. The device has a spinning device 10 for spinning the continuous filaments 2 and these spun continuous filaments 2 are introduced into a cooling device 11 with a cooling chamber 12. Preferred and in the embodiment according to Fig. 1 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 these air supply cabins 13, 14 arranged one above the other. It is recommended, and in the exemplary embodiment, that a monomer suction device 15 is arranged between the spinning device 10 and the cooling device 11. With this monomer suction device 15, interfering gases occurring during the spinning process can escape from the device removed. These gases are, for example, monomers, oligomers or decomposition products and similar substances.

The cooling device 11 is preferred and, in the exemplary embodiment, a stretching device 16 for stretching the continuous filaments 2 is connected downstream in the filament flow direction. Preferably 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 the 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 in this unit.

A diffuser 19, through which the continuous filaments 2 are guided, adjoins the stretching device 16, preferably and in the exemplary embodiment in the filament flow direction. After passing through the diffuser 19, the endless filaments 2 are deposited, preferably and in the exemplary embodiment, on a depositing conveyor designed as a depositing screen belt 20. The depositing screen belt 20 is preferred and, in the exemplary embodiment, is designed as an endlessly revolving depositing screen belt 20. This storage screen belt 20 is expediently made air-permeable, so that process air can be extracted from below through the storage screen belt 20.

According to a preferred embodiment and in the exemplary embodiment, the diffuser 19 has two opposite diffuser walls, two lower diverging diffuser wall sections 21, 22 being provided. These diverging diffuser wall sections 21, 22 are preferably with respect to the Center plane M of the device or of the diffuser 19 is asymmetrical. Expediently and in the exemplary embodiment, the inlet-side diffuser wall section 21 forms a smaller angle β with the central plane M than the outlet-side diffuser wall section 22. It is recommended that the angle β that the inlet-side diffuser section 21 forms with the central plane M is at least 1 ° smaller than the angle β which the outlet-side diffuser wall section 22 encloses with the center plane M. It is within the scope of the invention that the conveyor-side or sieve belt-side ends of the diverging diffuser wall sections 21, 22 have different distances e ₁ and e ₂ from the center plane M of the device or of the diffuser 19. The distance e _{1 of} the sieve belt-side end of the inlet-side diffuser wall section 21 to the central plane M is preferred and, in the exemplary embodiment, less than the distance e _{2 of} the sieve belt-side end of the outlet-side diffuser wall section 22 to the central plane M. The terms inlet-side and outlet-side relate in particular to the The conveying direction of the depositing screen belt 20 or the conveying direction of the nonwoven web. According to a preferred embodiment of the invention, the ratio of the distances e ₁ : e _{2 is} 0.6 to 0.95, preferably 0.65 to 0.9 and in particular 0.7 to 0.9. The asymmetrical configuration of the diffuser 19 in relation to the central plane M has proven particularly useful in terms of solving the technical problem according to the invention.

Furthermore, it is within the scope of the invention that two opposite secondary air inlet gaps 24, 25 are provided at the inflow end 23 of the diffuser 19, each of which is assigned to 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 in relation to the conveying direction of the depositing screen belt 20 or in relation to the machine direction (MD) than through the secondary air inlet gap on the outlet side 25. It is recommended that the secondary air volume flow of the inlet-side secondary air inlet gap 24 is at least 5%, preferably at least 10% and in particular at least 15% less than the secondary air volume flow through the outlet-side secondary air inlet gap 25. The embodiment with the different secondary air volume flows is in Particularly proven in terms of solving the technical problem according to the invention.

It is within the scope of the invention that there is at least one suction device (not shown in the figures) with which air or process air is sucked through the depositing screen belt 20 in a main suction area 27 below the deposit area 26 of the filaments 2. This air or process air is sucked through the depositing screen belt 20 at a suction speed v _H. The main suction area 27 is expediently and in the exemplary embodiment delimited below the depositing screen belt 20 in an inlet area and in an outlet area of the depositing screen belt 20 by a suction partition 28.1, 28.2.

A highly recommended embodiment of the invention is characterized in that the sieve belt-side end of the outlet-side suction partition 28.2 maintains a vertical distance A to the depositing conveyor or to the depositing sieve belt 20, this distance A preferably 25 mm to 200 mm and particularly preferably 28 mm to 150 mm mm. It is recommended, and in the exemplary embodiment, that a partition section designed as a spoiler section 30 is connected to the outlet-side suction partition 28.2 in its screen belt-side region. Preferably, and in the exemplary embodiment, the spoiler section 30 is, as it were, an integral component of the outlet-side suction partition 28.2 and is designed as an angled partition section on this suction partition 28.2. The spoiler section is expedient 30 is designed as an obliquely angled spoiler section 30 with a linear or essentially linear cross section. Preferably, and in the exemplary embodiment, the spoiler section 30 is angled to the side of the associated suction partition 28.2 facing away from the center plane M of the main suction area 27. It is within the scope of the invention that the end of the spoiler section 30 on the screen belt side maintains the above-mentioned distance A from the depositing conveyor or from the depositing screen belt 20. The preferably provided vertical distance A and in particular the embodiment with the spoiler section 30 are of particular importance with regard to the production of defect-free nonwoven webs. With the aid of this embodiment, it is possible for the relatively high suction speed v _H in the main suction area 27 to decrease continuously and linearly and gradually to a lower suction speed in the following area. In this way, disadvantageous blow-back effects on the nonwoven web can be successfully avoided. As a result, nonwoven webs can be produced without disruptive filament aggregates and thus nonwoven webs with a very homogeneous surface structure or surface structure.

Preferably and in the exemplary embodiment, a second suction area 29 is connected downstream of the main suction area 27, in which air or process air is sucked through the depositing conveyor or through the depositing screen belt 20 at a suction speed v ₂ . This suction speed v ₂ is lower or significantly lower than the suction speed v _H in the main suction area 27. The realization of the preferably provided vertical distance A and in particular the realization of the spoiler section 30 thus ensures a gradual, continuous transition of the suction speeds from the high suction speed v _H in the main suction area to the lower suction speed v ₂ in the second suction area 29.

especially the Fig. 2 shows a particularly preferred embodiment in relation to the pre-consolidation devices and in relation to the suction gap section 34 in the area of the deposit conveyor or the depositing screen belt 20. Preferably and in the exemplary embodiment, a first hot-air pre-consolidation device is arranged in the conveying direction behind the deposit area 26 of the filaments, which is recommended and is designed as a hot air knife 31 in the exemplary embodiment. This first hot air pre-consolidation device or this hot air knife 31 is established and, in the exemplary embodiment, is arranged above the second suction area 29, in which process air is sucked through the storage screen belt 20 at the suction speed v ₂ . It is recommended that the distance B of the first hot air pre-consolidation device or the hot air knife 31 to the center plane M of the device is 100 mm to 1,000 mm, preferably 110 mm to 600 mm and preferably 120 mm to 550 mm. The distance B is measured in particular between the mentioned center plane M and the first component or structural component of the first hot air pre-consolidation device or of the hot air knife 31 following in the conveying direction.

The first hot air pre-consolidation device or the hot air knife 31 is followed in the machine direction (MD) by a second hot air pre-consolidation device, which is preferably designed as a hot air oven 32 in the exemplary embodiment. The distance C or horizontal distance C measured in the machine direction (MD) between the first hot air pre-consolidation device and the second hot air pre-consolidation device or between the hot air knife 31 and the hot air oven 32 is expediently 400 mm to 5,200 mm and in particular 1,100 mm to 4,700 mm . In the area of the second hot-air pre-consolidation device or in the area of the hot-air oven 32, there is preferably and in the exemplary embodiment a further suction of process air through the depositing screen belt 20 here process air is sucked off at a suction speed v ₃ in a third suction area 33. The individual suction areas below the depositing screen belt 20 are also preferred and in the exemplary embodiment according to FIG Fig. 2 separated from one another by partitions 35. It is within the scope of the invention that the suction speed v ₃ in the third suction area 33 below the hot air oven 32 is lower than the suction speed v ₂ in the second suction area 29.

The suction gap section 34 according to the invention is arranged between the first hot air pre-consolidation device and the second hot air pre-consolidation device. The length L of the suction gap section 34 in the machine direction (MD) is preferably and in the exemplary embodiment at least 80% of the distance C between the first hot air pre-consolidation device and the second hot air pre-consolidation device. According to a recommended embodiment of the invention, there is no suction of process air through the depositing screen belt 20 in the suction gap section 34, so that here the suction speed v _{L is} equal to zero or approximately equal to zero. According to another embodiment, a slight suction of process air takes place in the suction gap section 34 through the depositing screen belt 20. The suction speed v _L in the suction gap section 34 is then preferably lower or significantly lower than the suction speed v ₂ in the second suction area 29. According to a recommended embodiment of the invention, the suction speed v _{L is} also lower than the suction speed v ₃ in the third suction area 33 below the second hot air preconsolidation device.

The Fig. 2 further shows a particularly preferred embodiment of a device according to the invention. In this embodiment variant, a third pre-consolidation device can be introduced into the suction gap section 34 that in the embodiment according to Fig. 2 is designed as a pair of compacting rollers 36. If necessary, the compacting roller 37 can be pivoted onto the depositing screen belt 20 from above, while the compacting roller 38 is pivoted onto the depositing screen belt 20 from below. With the aid of the pair of compacting rollers 36, the nonwoven web can be compacted in the suction gap section 34. If compaction of the nonwoven web is not desired, the pair of compacting rollers 36 can be removed or swiveled out of the area of the depositing screen belt 20 or the suction gap section 34. In this respect, the device according to the invention with the suction gap section 34 according to the invention is also characterized by a high degree of flexibility and variability with regard to the pre-consolidation possibilities. A compacting roller 37, 38 expediently has a diameter Z of 200 mm to 500 mm, preferably 250 mm to 450 mm. It is within the scope of the invention that the diameter Z of a compacting roller 37, 38 is not greater than the length L of the suction gap section 34 and is advantageously smaller than the length L of the suction gap section 34. In principle, according to one embodiment, a Maintenance web (not shown in the figures) can be arranged, which extends transversely to the machine direction (MD) and ensures easy accessibility of the system components for the maintenance personnel or operating personnel. This embodiment can be provided in particular if there is no suction of process air in the suction gap section 34 and the suction speed v _L is therefore zero or approximately zero there.

If, according to the embodiment of the invention explained above, an upper compacting roller 37 is arranged in the suction gap section 34, this compacting roller 37 has distances X and Y to the neighboring ones Hot air pre-consolidation devices. It is within the scope of the invention that the distance X and / or the distance Y is smaller than the diameter Z of the compacting roller 37. The distance X is the distance between the upper compacting roller 37 and the first hot air pre-consolidation device or to the hot air knife 31 and the distance Y is the distance from the upper compacting roller 37 to the second hot air preconsolidation device or to the hot air oven 32. Both distances X and Y are like the length L of the suction gap section 34 and the distance C between the both hot air pre-consolidation devices in the machine direction (MD) and expediently measured horizontally in the machine direction (MD). It is within the scope of the invention that the distance X between the hot air knife 31 and the upper compacting roller 37 is 100 mm to 500 mm, preferably 150 mm to 450 mm. Furthermore, it is within the scope of the invention that the distance Y between the upper compacting roller 37 and the hot air oven 32 is 50 mm to 1,500 mm and preferably 100 mm to 1,000 mm.

The fibers or continuous filaments 2 produced with the device according to the invention or with the method according to the invention are expediently bicomponent filaments or multicomponent filaments. These are preferably bicomponent filaments or multicomponent filaments with a side-by-side configuration or with an eccentric core-sheath configuration. Particularly preferred within the scope of the invention are bicomponent filaments or multicomponent filaments with an eccentric core-sheath configuration and very particularly preferably with an eccentric core-sheath configuration of the Fig. 3 Art. In the Fig. 3 a cross section through a continuous filament 2 with the preferred special core-sheath configuration is shown. In the case of these continuous filaments 2, the sheath 3 preferably overlaps in the filament cross section and in the exemplary embodiment more than 50%, preferably over more than 55% of the filament circumference, has a constant thickness d or an essentially constant thickness d. 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 - viewed in the filament cross section - is configured in the shape of a segment of a circle. Expediently and in the exemplary embodiment, this core 4 has an arcuate circumferential section 5 and a linear circumferential section 6 with respect to its circumference. Preferably, and in the exemplary embodiment, the circular arc-shaped circumferential section of the core 4 takes up over 50%, preferably over 55% 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 in the range of its constant thickness is preferably 0.5% to 8%, in particular 2% to 10% of the filament diameter D. In the exemplary embodiment, the thickness d of the jacket 3 may be in the range of its constant Thickness is 0.05 µm to 3 µm.

Claims (16)

Apparatus for producing a nonwoven fabric (1) from crimped fibers, in particular from crimped continuous filaments (2), at least one spinning device (10) or at least one spinning beam being provided for spinning the fibers, with an air-permeable storage conveyor, in particular a storage screen belt (20) for depositing the fibers in a deposit area (26) to form a nonwoven web,
at least one first pre-consolidation device for pre-consolidation of the nonwoven web is arranged in the conveying direction of the nonwoven web behind the deposit area (26), with at least one suction device being provided with the air or process air in the deposit area (26) of the fibers and / or in the area of the first The pre-consolidation device can be suctioned by the depositing conveyor or by the depositing screen belt (20),
wherein at least one second pre-consolidation device for pre-consolidation of the nonwoven web is connected downstream of the first pre-consolidation device in the conveying direction of the nonwoven web, wherein in the area of the second pre-consolidation device air or process air can be sucked through the deposit conveyor or through the deposit screen belt (20)
and wherein in the area between the first pre-consolidation device and the second pre-consolidation device, at least one suction gap section (34) is arranged, with no suction of air or process air by the depositing conveyor or by the depositing screen belt (20) taking place in the suction gap section (34) and / or wherein the suction gap section (34) is set up with the proviso that there is less or significantly less suction of air or process air than in the storage area (26) of the fibers and / or in the area of the first pre-consolidation device and / or that there less or significantly less suction of air or process air takes place than in the area of the second pre-consolidation device. Apparatus according to claim 1, wherein the entire suction gap section (34) is arranged on the depositing conveyor on which the fibers can be deposited to form the nonwoven web and on which the pre-consolidations with the at least two pre-consolidation devices take place. Device according to one of Claims 1 or 2, only a first pre-consolidation device being provided between the storage area (26) for the fibers and the suction gap section (34). Device according to one of claims 1 to 3, wherein in the storage area (26) of the fibers in a main suction area (27) air or process air can be sucked in by the depositing conveyor and wherein between the main suction area (27) and the suction gap section (34) a second suction area ( 29) is arranged for the suction of air or process air through the delivery conveyor, the second suction area (29) being provided in the area or under the first pre-consolidation device and wherein the air velocity v ₂ in the second suction area (29) is preferably lower than the Air speed v _H of the air extracted in the main extraction area (27). Device according to one of Claims 1 to 4, the at least one first pre-consolidation device being designed as a hot-air pre-consolidation device and preferably designed as a hot air knife (31). Device according to one of claims 1 to 5, wherein in the suction gap section (34) at least one third pre-consolidation device on the Storage conveyor can be positioned and is preferably removable from the storage conveyor if necessary. Apparatus according to claim 6, wherein the third pre-consolidation device is designed in the form of at least one compacting roller (37, 38), in particular in the form of at least one compacting roller pair (36), and wherein the compacting roller (37, 38) or the compacting roller pair (36) for positioning the storage conveyor can preferably be pivoted onto the storage conveyor and is expediently pivotable away from the storage conveyor in order to remove it from the storage conveyor. Device according to one of claims 1 to 7, wherein the at least one second pre-consolidation device is designed as a hot-air pre-consolidation device and is preferably designed as a hot-air oven (32). Apparatus according to one of claims 1 to 8, wherein in the region of the at least one second pre-consolidation device or in the region of the second hot air pre-consolidation device, process hot air can be sucked through the depositing screen belt (20) in a third suction region (33) at a speed v ₃ and the suction speed v ₃ being lower than the suction speed v ₂ in the second suction area (29) and lower than the suction speed v _H in the main suction area (27). Process for the production of a nonwoven fabric (1) from crimped fibers, in particular from crimped continuous filaments (2) - preferably with a device according to one of claims 1 to 9 - wherein the fibers or filaments (2) are spun and on an air-permeable storage conveyor or . are deposited on an air-permeable storage screen belt (20),
wherein in the storage area (26) of the fibers air or process air is sucked in a main suction area (27) through the storage conveyor or through the storage screen belt (20) and wherein in the machine direction (MD) behind the storage area (26) the fibers are in at least one pre-consolidation stage are preconsolidated on the storage conveyor, with air or process air being sucked in a second suction area (29) through the storage conveyor or through the storage screen belt (20) in the area of the first preconsolidation stage,
wherein the fibers are pre-consolidated in at least one of the second pre-consolidation stage downstream of the first pre-consolidation stage in the machine direction (MD) on the storage conveyor or on the storage screen belt (20), with air or process hot air in a third suction region (33) in the area of the second pre-consolidation stage is sucked through the storage conveyor or through the storage screen belt (20)
and wherein in the area between the first pre-consolidation stage and the second pre-consolidation stage, at least one suction gap section (34) is arranged in which no air or process air is sucked through the deposit conveyor or through the depositing screen belt (20) and / or in which a lower or significantly less suction of air or process air is carried out than in the second suction area (29). Method according to claim 10, wherein in the suction gap section (34) there is less suction of air or process air by the depositing conveyor or by the depositing screen belt (20) than in the third suction area (33) in the area of the second pre-consolidation stage. Method according to claim 10, wherein in the suction gap section (34) a higher suction of air or process air by the depositing conveyor or takes place through the depositing screen belt (20) than in the third suction area (33) in the area of the second pre-consolidation stage. Method according to one of claims 10 to 12, wherein in the suction gap section (34) air is sucked off at a suction speed v _L through the depositing conveyor or through the depositing screen belt (20), and this suction speed v _{L is} less than the suction speed v _{2 of} the suction of process air in the second suction area (29). Method according to one of claims 10 to 13, wherein the suction speed v _L in the suction gap section (34) is lower than the suction speed v _{3 of} the suction of process air in the third suction area (33) in the area of the second pre-consolidation stage or wherein the suction speed v _L in the suction gap section (34) is greater than the suction speed v ₃ in the third suction area (33). Method according to one of Claims 10 to 14, wherein a third pre-consolidation device - in particular in the form of at least one compacting roller (37, 38) - is introduced into the suction gap section (34) and the third pre-consolidation device is preferably removed from the suction gap section (34) again if required. Will get removed. A method according to any one of claims 10 to 15, wherein crimped or crimped filaments are produced as bicomponent filaments or multicomponent filaments with an eccentric core-sheath configuration and wherein these filaments (2) preferably have a sheath (3) which in the filament cross-section over at least 20 %, in particular over at least 25%, preferably over at least 30%, proven measure over at least 35% and very preferably over at least 40% and particularly preferably over at least 45% of the filament circumference has a constant thickness d or a substantially constant thickness d.

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