Production method and production apparatus for nonwoven fabric made of crimped synthetic fibers

Abstract

A method for producing a nonwoven fabric made of crimped synthetic fibers, in which the synthetic fibers are spun and deposited as a nonwoven web on a conveyor. The deposited nonwoven web is pre-bonded by at least one first hot air bonder, and primary suction air is drawn from below through the conveyor in the area of ​​fiber deposition. Primary suction air is drawn from below through the conveyor in the region of the first hot air bonder. The air velocity of the primary suction air is higher than the air velocity of the primary suction air.

Description

Technical Field

[0001] The present invention relates to a method for producing a nonwoven fabric made of crimped synthetic fibers, wherein the synthetic fibers are spun and deposited as a nonwoven web on a conveyor. The present invention further relates to a corresponding apparatus for producing a nonwoven web made of crimped synthetic fibers. Potentially including crimping the synthetic fibers is within the framework of the present invention. Further, using the crimped continuous synthetic filaments as crimped continuous filaments is within the framework of the present invention.

Background Art

[0002] Methods for producing nonwoven fabrics made of crimped synthetic fibers are practically known in various configurations. This is especially true for spunbond webs produced by the spunbond method. In this case, in many applications, it is desirable for the spunbond web to have a large volume and at the same time sufficient stability or strength. However, within the framework of producing a spunbond web, these two properties usually have competing properties or effects. A large volume is often obtained at the expense of strength, and vice versa. Also, it is desirable for the spunbond web to have sufficient homogeneity. For economic reasons, a high production speed is desired during the production of the spunbond web. In order to obtain a high production speed during the production of a voluminous spunbond web, it is usually necessary to accept a loss of the strength and homogeneity of the spunbond web. These are highly undesirable disadvantages. In this regard, improvements are needed.

[0003] In the process of producing a spunbond web, it is also known that the nonwoven web deposited on the perforated deposition belt is stabilized by the air sucked through the perforated deposition belt. At this time, it becomes a problem that the nonwoven web transferred by the perforated deposition belt from the suction area to the non-suction area is subject to a so-called blowback effect. At the starting point of the non-suction area, the fibers of the nonwoven web to be further conveyed are as if sucked back by the suction air in the suction area, and chaotic inhomogeneities are formed in the nonwoven web. Therefore, the homogeneity of the nonwoven web is often left undesired.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention is based on the technical problem of providing a method of the type described at the beginning that can produce a voluminous nonwoven web with optimal homogeneity while having sufficient stability or strength at a high production speed. The present invention is further based on the technical problem of providing a corresponding apparatus for producing such a nonwoven fabric.

Means for Solving the Problems

[0005] To solve the technical problem, the present invention teaches a method for producing a nonwoven fabric made of crimped synthetic fibers. The synthetic fibers are spun and deposited as a nonwoven web on a conveyor, and the deposited nonwoven web is pre-bonded by a first hot air bonding device. Here, the main suction air is sucked downward through the conveyor in the area of fiber deposition, the first suction air is sucked downward through the conveyor in the area of the first hot air bonding device, and the wind speed of the main suction air is higher than the wind speed of the first suction air.

[0006] It is within the framework of the present invention and preferable that the synthetic fibers undergo final hot air bonding after the first hot air bonding. One possible final hot air bonding is carried out using a belt oven. In such a belt oven, hot air flows through the fibers to solidify the final product. In a preferred embodiment, the hot air temperature and air velocity used are lower than those in the first hot air bonding.

[0007] The first hot air bonding device generates a flow of the first hot air, which acts on the non-woven web from above as appropriate to bring about pre-bonding. It is within the framework of the present invention that the main suction air is suctioned through the conveyor below the fiber deposition area. Further, it is also within the framework of the present invention that the first suction air is suctioned through the conveyor below the hot air bonding device. A particularly recommended embodiment of the present invention is characterized in that the conveyor is configured as a perforated deposition belt or a continuously circulating perforated deposition belt.

[0008] It is within the framework of the method according to the present invention that the non-woven fabric is produced as a spunbond non-woven fabric, and the continuous synthetic filaments are spun, cooled, drawn, and then deposited on a conveyor or on a perforated deposition belt as a spunbond non-woven web. Therefore, the synthetic fibers used within the framework of the present invention include continuous synthetic filaments.

[0009] A particularly preferred embodiment of the spunbond method according to the invention or of the spunbond apparatus according to the invention for carrying out the method will be described below. Optionally, continuous filaments - in particular in the form of bicomponent filaments and / or multicomponent filaments - are spun with the aid of a spinneret and are then guided through a cooling device for cooling the filaments. Preferably, at least one monomer suction device is arranged between the spinneret and the cooling device, whereby suction from the filament-forming space takes place immediately below the spinneret, so that, in addition to air, gases such as decomposition products, monomers, oligomers and the like generated during the spinning of the filaments can be removed from the apparatus. It is recommended that the filament curtain produced by the spinneret in the cooling device be exposed to cooling air from both sides. A very preferred embodiment - which is of particular importance within the framework of the method according to the invention - is characterized in that the cooling device is divided into at least two cooling chamber sections arranged continuously in the direction of flow of the filaments, and it is preferred that cooling air of different temperatures can be supplied to each section. A stretching device is installed behind or below the cooling device in the direction of flow of the filaments, and it has been found that the filaments passing through the cooling device can be successfully pulled or stretched by the stretching device. The cooling device is optionally directly adjacent to an intermediate passage, which is preferably configured to converge for the deposition of the filaments or to converge in a wedge shape. After passing through the intermediate passage, the filament curtain preferably enters the draw-down passage of the stretching device or the stretching shaft. A particularly recommended embodiment of the invention is characterized in that the unit formed from the cooling device and the stretching device or the unit formed from the cooling device and the intermediate passage and the stretching shaft is a closed unit. By a closed unit is meant herein that, apart from the supply of cooling air in the cooling device, no further air is supplied into this unit and the unit is configured to be closed to the outside.

[0010] A preferred embodiment of the present invention further features that the continuous filaments emerging from the stretching device are guided through a laying unit comprising at least one diffuser. According to one embodiment, at least two continuously arranged diffusers are installed. Optionally, after passing through the laying unit or at least one diffuser, the filaments are deposited onto a conveyor or onto a perforated deposition belt. Here, the filaments are deposited to form a spunbond web.

[0011] Within the framework of the method according to the present invention, it is within the framework of the present invention that the diffuser used has two opposing diffuser walls, and the walls extend across the machine direction and thus in the CD direction. The machine direction means, within the framework of the present invention, in particular, the conveying direction of the non-woven web on the perforated deposition belt. According to an embodiment of the present invention which is highly recommended, the distance from the perforated deposition belt to at least one diffuser is adjustable. This includes, in particular, the distance of the diffuser arranged immediately above the perforated deposition belt. Further, within the framework of the present invention, the distance between the diffuser walls and / or the angle between the diffuser walls is adjustable. In particular, the adjustment of the distance between the perforated deposition belt and the diffuser arranged immediately above the perforated deposition belt is particularly important within the framework of the present invention and from the perspective of solving the technical problems according to the present invention. Preferably, the distance between the perforated deposition belt and the diffuser is 5 mm to 150 mm, particularly preferably 5 mm to 100 mm.

[0012] Particularly preferred embodiments of the present invention are characterized in that within the framework of the method according to the invention, a multilayer nonwoven web is produced, wherein the nonwoven layers or spunbond layers used are each produced according to the methods described above or using the apparatus described previously. At least one spinneret or at least one spinning beam is assigned to each nonwoven layer. According to a particularly preferred embodiment, the means according to the invention described above and hereinafter in connection with the treatment of the nonwoven web on the conveyor (in particular, pre-bonding means and / or suction means) are carried out after each nonwoven layer has been applied to the conveyor or the perforated deposition belt. Optionally, these means are carried out for at least a part of the nonwoven layers of the nonwoven laminate.

[0013] The spinning of synthetic fibers or continuous filaments as bicomponent filaments and / or multicomponent filaments is within the framework of the present invention. Preferably, in this case, at least one component or synthetic component consists of or consists essentially of polyolefin. Embodiments that are strongly recommended are characterized in that in bicomponent filaments or multicomponent filaments, at least two components or at least two synthetic components contain polyolefin, or consist of polyolefin, or consist essentially of polyolefin. Proven embodiments of the present invention are characterized in that bicomponent filaments and / or multicomponent filaments are spun in a parallel configuration and / or an eccentric core-sheath configuration. In principle, other configurations of bicomponent filaments and / or multicomponent filaments that allow for potential crimping of the filaments are possible.

[0014] Preferably, within the framework of the present invention, at least one component contains or consists of or consists essentially of polypropylene and / or polyethylene, and bicomponent filaments and / or multicomponent filaments are used. According to a preferred embodiment, bicomponent filaments are produced in which one component contains or consists of or consists essentially of polypropylene and the other component contains or consists of or consists essentially of polyethylene. These bicomponent filaments are known to have a parallel configuration and / or an eccentric core-sheath configuration. When one component of the bicomponent filament contains or consists of or consists essentially of polypropylene and the other component contains or consists of or consists essentially of polyethylene, the mass ratio of the two components, polypropylene: polyethylene, is preferably from 20:80 to 80:20. When using polypropylene, it is recommended that the polypropylene be selected to have a melt flow rate (MFR) of 25 to 100 g / 10 min (230 °C / 2.16 kg), preferably 30 to 80 g / 10 min, and very preferably 35 to 60 g / 10 min.

[0015] The first hot air bonding device blows the first hot air to pre-bond the nonwoven web, and it is within the framework of the present invention that the wind speed of the main suction air is higher than the wind speed of the first hot air. Preferably, the wind speed of the first suction air is higher than or equal to the wind speed of the first hot air of the first hot air bonding device.

[0016] According to a preferred embodiment of the present invention, the second suction air is sucked from below through a conveyor or from below through a perforated deposition belt between the fiber deposition area and the area of the first hot air bonding device. In the conveying direction of the non-woven web, the fiber deposition area, the suction area of the second suction air, and the area of the first hot air bonding device are arranged continuously. In this case, within the framework of the present invention, it is also possible that the suction of the main suction air, the suction of the second suction air, and the suction of the first suction are arranged continuously or directly continuously in the conveying direction of the non-woven web.

[0017] Optionally, the wind speed of the second suction air is lower than that of the main suction air. Preferably, the wind speed of the main suction air is 5 m / s to 25 m / s, very preferably 8 m / s to 20 m / s, and even more preferably 10 m / s to 15 m / s. The wind speed of the second suction air is optionally 2 m / s to 15 m / s, very preferably 3 m / s to 12 m / s, and even more preferably 5 m / s to 10 m / s. It is recommended that the wind speed of the second suction air be higher than that of the first suction air. Preferably, the wind speed of the second suction air is 10% to 50% higher than that of the first suction air, particularly preferably 15% to 30% higher than that of the first suction air, and very preferably 18% to 25% higher than that of the first suction air.

[0018] Optionally, the first hot air bonding device is configured as a hot air knife. It is recommended that the distance from the conveyor or the perforated deposition belt to the first hot air device can be adjusted. Preferably, the distance from the conveyor or the perforated deposition belt to the first hot air bonding device is 2 mm to 50 mm, particularly preferably 5 mm to 25 mm. Furthermore, it is recommended that the angle between the hot air coming out of the first hot air bonding and the conveyor or the perforated deposition belt can be adjusted. According to one embodiment, the angle between the hot air coming out of the first hot air bonding and the conveyor or the perforated deposition belt is 90°, and preferably, it can be adjusted within the range of ±20°. A preferred embodiment of the present invention is characterized in that the temperature of the hot air of the first hot air bonding device or the first hot air knife can be adjusted. Preferably, the temperature of the hot air blown from the first hot air bonding device is 80 to 180 °C, preferably 100 to 175 °C, and even more preferably 125 °C to 170 °C.

[0019] In a particularly important embodiment within the framework of the present invention, after a first hot air bonding device installed in the conveying direction of the non-woven web, the non-woven web is bonded or pre-bonded by a second hot air bonding device, and the second hot air is blown onto the non-woven web by the second hot air bonding device.

[0020] According to a preferred embodiment of the present invention, preferably, the distance from the conveyor or the perforated deposition belt to the second hot air bonding device is adjustable. Preferably, the distance from the conveyor or the perforated deposition belt to the second hot air bonding device is in the range of 10 mm to 300 mm, particularly preferably 50 mm to 200 mm.

[0021] Preferably, the angle between the hot air blown from the second hot air bonding device and the conveyor or the perforated deposition belt is about 90°, and can be adjusted by 0 to 10° on either side. Appropriately, the second hot air bonding device is configured as a hot air knife or a hot air furnace. It is recommended that the temperature of the hot air blown from the second hot air bonding device can be adjusted. Preferably, the temperature of the hot air blown from the second hot air bonding device is 80 to 180 °C, preferably 100 to 150 °C, particularly preferably 125 °C to 145 °C.

[0022] A very preferred embodiment of the method according to the present invention is characterized in that the wind speed of the first hot air of the first hot air bonding device is higher than the wind speed of the second hot air of the second hot air bonding device.

[0023] Preferably, the wind speed of the first hot air of the first hot air bonding device is 1 m / s to 5 m / s (for example, 2.6 m / s), very preferably 1.5 m / s to 4 m / s, more preferably less than 3 m / s, and the wind speed of the second hot air of the second hot air bonding device is preferably 10% to 50% lower than the wind speed of the first hot air of the first hot air bonding device, particularly 15% to 30% (for example, 2.0 m / s) lower, and very preferably 18% to 30% lower.

[0024] Suitably, the first hot air of the first hot air combining device has a higher temperature than the second hot air of the second hot air combining device. An evidenced embodiment of the present invention is characterized in that the first hot air combining device has a smaller air treatment area or pre-bonding area with respect to the nonwoven web to be treated than the second hot air combining device when viewed in the conveying direction of the nonwoven web. The air treatment area and thus the pre-bonding area of the second hot air combining device is thus 35 mm to 110 mm when viewed in the conveying direction of the nonwoven web, and the width (in the conveying direction) of the outlet for the second hot air of the second hot air combining device is 110 mm to 1100 mm.

[0025] It is within the framework of the present invention that the first hot air of the first hot air combining device has a different temperature and / or a different air velocity and / or a different air treatment cross-section than the second hot air of the second hot air combining device. In this case, furthermore, it is within the framework of the present invention that the first hot air of the first hot air combining device has a higher temperature and / or a higher air velocity and / or a smaller air treatment cross-section with respect to the nonwoven web to be pre-bonded than the second hot air of the second hot air combining device in order to create a cooling gradient.

[0026] An embodiment of the present invention that is strongly recommended is characterized in that the third suction air is suctioned from below through the conveyor or through the perforated deposition belt in the area of the second hot air combining device. Preferably, the air velocity of the third suction air is lower than the air velocity of the second hot air emerging from the second hot air combining device. An embodiment of the present invention that is strongly recommended is further characterized in that the air velocity of the main suction air is higher than the air velocity of the second hot air emerging from the second hot air combining device.

[0027] Preferably, the air velocity of the second hot air is 1.1 m / s to 2.6 m / s, particularly preferably 1.2 m / s to 2.4 m / s. It is recommended that the air velocity of the first suction air is higher than the air velocity of the second hot air emerging from the second hot air combining device.

[0028] A special embodiment of the present invention is characterized in that, between the suction region of the first suction air and the suction region of the third suction air, the fourth suction air is sucked from below through a conveyor or a perforated deposition belt. Preferably, the wind speed of the fourth suction air is lower than the wind speed of the first suction air. Appropriately, the wind speed of the fourth suction air is higher than the wind speed of the third suction air. Therefore, the suction of the first suction air, the suction of the fourth suction air, and the suction of the third suction air being continuously arranged in the conveying direction of the nonwoven web is within the framework of the present invention. In this case, appropriately, the wind speed decreases from the suction of the first suction air to the suction of the third suction air. The first suction air, therefore, has the highest wind speed among the three suction airs, especially to match the preferred gradient of the hot air speed and the existing degree of bonding. The fourth suction air has the second highest wind speed, and the third suction air has the third highest wind speed.

[0029] It is within the framework of the present invention that the first hot air bonding device and / or the second hot air bonding device is formed as a pre-bonding device for the nonwoven web. Preferably, both, i.e., the first and the second hot air bonding devices, are designed as pre-bonding devices. Further, after this (these) pre-bonding in the conveying direction of the filaments, the nonwoven web is finally solidified. Preferably, the nonwoven web is finally solidified with hot air. According to a recommended embodiment of the present invention, the pre-bonding is first carried out by the first hot air bonding device, then further pre-bonding is carried out by the second hot air bonding device, and finally the final solidification is carried out by the final solidification device, and the final solidification is preferably carried out with hot air.

[0030] In the method according to the invention, it is within the framework of the invention that the conveying speed of the nonwoven web exceeds 120 m / min, preferably exceeds 130 m / min, exceeds 140 m / min and very preferably exceeds 150 m / min. Thus, within the framework of the invention, it is possible to operate at a relatively high production speed, for example exceeding 150 m / min. The invention is based on the discovery that in this case a stable nonwoven web can be obtained which has a high volume, high homogeneity and high strength. What is important here is that a fiber deposition is obtained in which the filaments are controllably arranged in the machine direction (MD) and across the machine direction (CD). Thus, the method according to the invention enables an easily controllable MD / CD ratio. As a result of the degree of freedom of the parameter range according to the invention, this ratio is controllable and can be set precisely and reproducibly. The homogeneity of the nonwoven web meets all requirements if the rules according to the invention are followed. According to the invention, a nonwoven web having a high volume and high strength can be advantageously produced at a clearly high production speed. The invention is furthermore based on the discovery that when realizing the air flow according to the invention, in particular the suction means according to the invention, the adverse blowback effect described initially can be avoided. This also greatly contributes to the fact that a homogeneous nonwoven web can be produced. When realizing the means according to the invention, it is within the framework of the invention that the nonwoven web according to the invention can be easily produced from a plurality of layers arranged one above the other. Each layer of such a nonwoven laminate or nonwoven laminate can thus be simply produced using the air supply means or hot air supply according to the invention.

[0031] According to a preferred embodiment of the method according to the invention, the bulk density is 0.06 g / cm 3 Hereinafter, preferably the bulk density is 0.05 g / cm 3 Hereinafter and particularly preferably the bulk density is 0.04 g / cm 3 The following nonwoven web or spunbond web is produced. 0.6 to 2.0 (N / 5 cm) / (g / m 2)The production of a non-woven web or a spunbond web having the above strength by the method according to the present invention falls within the framework of the present invention. The strength in the machine direction (MD) is preferably 20 N / 5 cm or more, and appropriately 25 N / 5 cm or more, preferably 30 N / 5 cm or more. These values and value ranges of bulk density and strength are particularly preferable for non-woven webs having a basis weight of 10 gsm to 50 gsm, preferably 15 gsm to 35 gsm, and very preferably 17 gsm to 25 gsm.

[0032] As used herein, "bulk density" is the relative density calculated from "mass / unit area" with respect to thickness and is represented in g / cm 3 .

[0033] Mass / unit area is measured according to WSP (World Economic Forum) 130.1 (2005). The minimum test area of 50,000 mm 2 is measured in a representative area of the web evenly across the width of the line, and the average value is calculated.

[0034] Thickness is tested herein based on WSP120.6 (2005) - Option A. The test pressure of the press on the sample is 0.5 kPa according to the standard, but the reading is taken after a contact time of 5 seconds. At least 10 measurements are performed on samples taken from the same representative position, and the average value is used to calculate the bulk density.

[0035] The tensile test standard used herein is WSP110.04 (05) - Option B, using a sample size of 50 x 200 mm, a pre-tension load of 0.5 N, a clamp distance of 100 mm, and a test speed of 200 mm / min. At least 10 samples for the MD and CD directions are taken from representative positions, and the results must be averaged. The results are expressed in N / 5 cm (width).

[0036] The present invention also relates to an apparatus for producing a nonwoven fabric made of a crimped synthetic fiber having a spinning device or a spinneret for spinning fibers. The apparatus is provided with a cooling device for cooling the fibers and a conveyor for depositing the fibers for the nonwoven web, the main suction area being installed immediately below the area of fiber deposition. In the main suction area, the main suction air can be sucked from below through the conveyor, and downstream of the area of fiber deposition in the conveying direction of the conveyor or the conveying direction of the nonwoven web, a first hot air bonding device is installed. The first hot air bonding device acts on the nonwoven web surface with the first hot air, and the first suction area is installed immediately below the first hot air contact device. Here, the first suction air can be sucked from below through the conveyor or through the nonwoven web.

[0037] It is within the framework of the present invention that the apparatus is designed as a spunbond apparatus for producing a nonwoven fabric from continuous filaments. Downstream of the cooling device in the conveying direction of the filaments, a stretching device for stretching the filaments is arranged, and at least one diffuser is arranged between the stretching device and the conveyor. A particularly preferred embodiment of the equipment according to the present invention is characterized in that the assembly of the cooling device and the stretching device forms a closed unit and does not include the supply of any more air except for the supply of cooling air.

[0038] The present invention will be described in detail below with reference to the following drawings showing only one preferred embodiment.

Brief Description of the Drawings

[0039]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

DETAILED DESCRIPTION OF THE INVENTION

[0040] The drawings show an apparatus according to the invention for carrying out a method according to the invention for producing a nonwoven web 14 in the form of a spunbond web made of crimped continuous filaments 1. The filaments are preferably and in a preferred embodiment crimped synthetic continuous filaments 1 formed as bicomponent filaments. In this case, it is within the framework of the present invention that each of the two components contains or consists of or consists essentially of a polyolefin. Preferably, one component is polypropylene and the other component is polyethylene.

[0041] Figure 1 shows a highly preferred embodiment of such an apparatus. This apparatus comprises a spinneret 2 for spinning continuous filaments 1. The spun continuous filaments 1 are led into a cooling device having a cooling chamber 4 and air supply cabins 5, 6 arranged on both sides of the cooling chamber. The cooling chamber 4 and the air supply cabins 5, 6 extend across the machine direction MD and thus in the CD direction of the apparatus. Cooling air is led into the cooling chamber 4 from the opposing air supply cabins 5, 6.

[0042] According to a preferred embodiment and in a preferred embodiment, each air supply cabin 5, 6 is divided into two cabin sections 16, 17 from which cooling air of different temperatures is supplied respectively. In a preferred embodiment, cooling air of a first temperature can be supplied from the upper cabin section 16 respectively, and cooling air of a second temperature different from the first temperature can be supplied from the two lower cabin sections 17 respectively. Dividing the air supply cabins 5, 6 or the cooling chamber 4 into two is important within the framework of the present invention. It has been demonstrated that according to the present invention, the technical problem can be solved particularly effectively and reliably by having a two-part or multi-part cooling chamber.

[0043] In the flow direction FS of the filaments, the stretching device 8 is arranged downstream of the cooling device 3. By means of the stretching device, the continuous filaments 1 are stretched. The stretching device 8 preferably and in a preferred embodiment has an intermediate passage 9 connecting the cooling device 3 to the stretching shaft 10 of the stretching device 8. A particularly recommended embodiment of the present invention is characterized in that the assembly of the cooling device 3 and the stretching device 8 or the unit of the cooling device 3, the intermediate passage 9 and the stretching shaft 10 is configured as a closed system. In this case, the closed system means that, in particular, except for the supply of cooling air in the cooling device 3, there is no other air supply to this assembly. Thus, the device of FIG. 1 is configured.

[0044] In a preferred embodiment, in the flow direction FS of the filaments, a diffuser 11 follows the stretching device 8, and the continuous filaments 1 are guided through this. According to a preferred embodiment and in a preferred embodiment, a secondary air intake gap 12 for guiding secondary air into the diffuser 11 is installed between the stretching device 8 or between the stretching shaft 10 and the diffuser 11. The introduction of secondary air also has particular advantageous importance within the framework of the present invention. Instead of only one diffuser 11 shown in FIG. 1, for example, two diffusers 11 can be arranged continuously or vertically in the filament flow direction FS of the continuous filaments 1. A strongly recommended embodiment is characterized in that the distance between the diffuser 11 arranged immediately above the perforated deposition belt 13 and the perforated deposition belt 13 can be adjusted. This adjustment of the distance between the lower edge of the diffuser 11 and the perforated deposition belt 13 is also important within the framework of the present invention. Preferably, the distance between the lower edge of the diffuser 11 and the perforated deposition belt 13 is 5 mm to 150 mm.

[0045] After passing through the diffuser 11, the continuous filament 1 is deposited onto a conveyor configured as a perforated deposition belt 13, preferably and in a preferred embodiment. The perforated deposition belt 13 is designed and recommended as a continuous circulating perforated deposition belt 13 in a preferred embodiment. The filament deposit or non-woven web 14 is conveyed or moved in the machine direction MD.

[0046] Figure 2 shows a first preferred embodiment of an apparatus according to the invention. The deposited non-woven web is pre-bonded using a (first) hot air bonding device 7. In this case, the non-woven web 14 is subjected to the action of a (first) hot air from above by the (first) hot air bonding device 7 and is thereby pre-bonded. This (first) hot air 15 is adjustable with respect to its temperature and / or its wind speed v VH1 and is recommended to be adjustable with respect to the angle of the first hot air bonding device 7 with respect to the non-woven web 14 or the perforated deposition belt 13, or the angle of the (first) hot air 15.

[0047] According to the invention, in the area 18 of fiber deposition, the main suction air 19 is sucked through the perforated deposition belt 13. Further, according to the invention, in the area of the (first) hot air bonding device 7, the first suction air 20 is sucked through the perforated deposition belt 13 or through the non-woven web 14 on the perforated deposition belt 13. For sucking the air flow, fans 21, 22 are appropriately installed below the perforated deposition belt 13.

[0048] The wind speed v of the main suction air 19 M being higher than the wind speed v of the first suction air 20 1 is within the framework of the invention. Further, the wind speed v of the main suction air 19 M is preferably and in a preferred embodiment higher than the wind speed v of the (first) hot air 15 H1 . According to one embodiment, the wind speed v M is from 10 m / s to 25 m / s, and the wind speed v of the (first) hot air H1 is from 1.5 m / s to 3 m / s. In a preferred embodiment, the wind speed v of the first suction air 20 1is higher than the wind speed v of the (first) hot air 15, and this is recommended. H1 and higher than this, and this is recommended.

[0049] Preferably and in the preferred embodiment of FIG. 2, the second suction air 23 is suctioned between the suction of the main suction air 19 and the suction of the first suction air 20. Appropriately, the wind speed v of this second suction air 23 2 is lower than the wind speed v of the main suction air 19 M and preferably higher than the wind speed v of the first suction air 20 1 According to a preferred embodiment, the wind speed V of the second suction air 23 2 is 2 to 13 m / s, more preferably 3 to 12 m / s. The wind speed profile is shown in the lower region of FIG. 2, showing the respective wind speeds v of the air suctioned through the non-woven web 14 and through the perforated deposition belt 13 with the help of the fans 21, 22 as a function of the respective positions in the transport direction. It can be seen that the wind speed v is the highest below the fiber deposition area 18 and then decreases to the hot air bonding device 7. Therefore, there is a decrease in speed from the wind speed v of the main suction air 19 M to the wind speed v of the second suction air 23 2 and then to the wind speed v of the first suction air 20 1 The suction areas of the air flows 19, 23, 20 are preferably and in the preferred embodiment defined by the partition wall 29 or separated from each other. According to a preferred embodiment of the present invention, these partition walls 29 are made to be adjustable or settable, and in this way, they affect the suction or the speed of the suction air.

[0050] Figure 3 shows another embodiment of the device according to the present invention. First, the components and the air flow are realized up to the first hot air bonding device 7 in the same manner as in the embodiment according to FIG. 2. Further, in this embodiment according to FIG. 3, preferably and in a preferred embodiment, a second hot air bonding device 24 configured as a hot blast stove is installed. Both the hot air bonding devices 7 and 24 are used for pre-bonding the nonwoven web 14. After these two pre-bondings, the nonwoven web 14 preferably undergoes final solidification, although not shown in FIG. 3. Appropriately, this final solidification of the nonwoven web 14 is also realized by hot air. In the second hot air bonding device 24, the nonwoven web 14 is pre-bonded by a second hot air 25 acting on the surface of the nonwoven web 14. This second hot air 25 has a wind speed v H2 The wind speed v H1 of the first hot air 15 of the first hot air bonding device 7 being higher than the wind speed v H2 of the second hot air 25 of the second hot air bonding device 24 is within the framework of the present invention. In a preferred embodiment, the wind speed v H2 of the second hot air 25 is at least 20% lower than the wind speed v H1 of the first hot air 15. Preferably and in a preferred embodiment, further, the first hot air 15 of the first hot air bonding device 7 has a higher temperature than the second hot air 25 of the second hot air bonding device 24. According to the recommended embodiment and in the preferred embodiment according to FIG. 3, the first hot air bonding device 7 has a narrower air treatment area 26 than the second hot air bonding device 24 when viewed in the conveying direction of the nonwoven web 14. It is recommended that the width of the air treatment area 26 of the first hot air bonding device 7 be 35 - 110 mm when viewed in the conveying direction of the nonwoven web 14. According to a preferred embodiment 5, the width of the air treatment area of the second hot air bonding device 24 is 110 - 1100 mm when viewed in the conveying direction of the nonwoven web 14.

[0051] Preferably and in a preferred embodiment, the third suction air 27 is sucked through the nonwoven web 14 or the perforated deposition belt 13 below the second hot air bonding device 24. This third suction air 27 preferably has a wind speed v H2 lower than the wind speed v 3has. In the recommended and preferred embodiments, further, the wind speed v of the main suction air 19 M and the wind speed v of the first suction air 20 1 are each higher than the wind speed v of the third suction air 27 3 .

[0052] From FIG. 3, according to the preferred embodiment and in the preferred embodiment, it can be seen that the fourth suction air 28 is sucked between the first hot air coupling device 7 and the second hot air coupling device 24 through the non-woven web 14 and through the perforated deposition belt 13. This fourth suction air 28 has a wind speed v 4 . Appropriately, this wind speed v of the fourth suction air 28 4 is lower than the wind speed v of the first suction air 20 1 and higher than the wind speed v of the third suction air 27 3 . According to the preferred embodiment, the wind speed v of the fourth suction air 28 4 is lower than 3 m / s, more preferably lower than 2 m / s. The lower region of FIG. 3 shows a preferred wind speed profile, showing the wind speed v as a function of the position below the conveyor or the perforated deposition belt 13. According to the preferred embodiment and in the preferred embodiment, the wind speed v decreases from the wind speed v of the main suction air 19 M to the wind speed v of the third suction air 27 3 . Also, FIG. 3 shows that the individual suction areas are separated from each other by a partition wall 29 - as in the preferred embodiment of FIG. 2. In the preferred embodiment, it is recommended that these partition walls 29 be adjustable so that they can change the suction cross-section of the flow of the individual suction air and thereby change the suction or suction speed. This possibility of adjustment has been proven to be successful especially within the framework of the present invention. The suction or suction speed can further be controlled and / or adjusted via the fans 21, 22.

[0053] Figure 4 shows a further preferred embodiment of the present invention. This embodiment differs from the embodiment according to FIG. 3 only in that the second hot air bonding device 24 is not configured as a hot air furnace, but rather as a hot air knife, similar to the first hot air bonding device 7. Both hot air bonding devices 7, 24 or both hot air knives are installed for pre-bonding the nonwoven web 14. Optionally, after two pre-bondings, final solidification of the nonwoven web 14 - not shown in FIG. 4 - is carried out, and the solidification is preferably carried out with hot air.

[0054] The wind speed profiles in FIGS. 2, 3 and 4 show that the wind speed v of the suction air decreases or continuously decreases in the transport direction from the fiber deposition area 18. As a result of this adjustment of the wind speed v according to the invention, the negative effect of blowback on the nonwoven web 14, which occurs particularly in the transition area between different suctions or in the transition area between different air flows, can be avoided. The present invention is based in this regard on the discovery that a defect-free homogeneous nonwoven web 14 can be produced by means according to the invention.

[0055] Figure 5 shows a preferred embodiment of an apparatus according to the invention for producing a multilayer nonwoven web 14 made of a plurality of spunbond webs S, in a preferred embodiment three spunbond webs S1, S2 and S3. To produce the individual spunbond webs S for the multilayer nonwoven web 14, a spinning beam or spinneret 2 is used in each case for spinning the respective continuous filaments 1. In this case, in each case the above-described spunbond apparatus is used to produce each of the spunbond webs S1, S2 and S3. After the deposition of each of the spunbond webs S1, S2 and S3, pre-bonding is carried out in each case by two hot air bonding devices 7, 24 in the form of hot air knives. The air flow and the wind speed preferably correspond in each case to those described in connection with FIGS. 3 and 4. Each of the spunbond webs S1, S2 and S3 is thus subjected to double pre-bonding with the hot air bonding devices 7, 24 after deposition onto the perforated deposition belt 13. After the laminate made of the three spunbond webs S1, S2 and S3 is completed, final solidification is preferably carried out by the final solidification device 30.

Claims

1. A method for producing a nonwoven fabric made of crimped synthetic fibers, wherein the synthetic fibers are spun and deposited on a conveyor as a nonwoven web (14), the deposited nonwoven web (14) is pre-bonded by at least one first hot air bonding device (7), main suction air (19) is sucked from below through the conveyor in the area (18) of the fiber deposition, first suction air (20) is sucked from below through the conveyor in the area of the first hot air bonding device (7), the wind speed (v Ｍ ) of the main suction air (19) is higher than the wind speed (v １ ) of the first suction air (20), the first hot air bonding device (7) blows first hot air (15), the wind speed (v Ｍ ) of the main suction air (19) is higher than the wind speed (v Ｈ１ ) of the first hot air (15), and the wind speed (v １ ) of the first suction air (20) is higher than or equal to the wind speed (v Ｈ１ ) of the first hot air (15).

2. The method according to claim 1, wherein the nonwoven fabric is provided as a spunbond nonwoven fabric, continuous synthetic filaments (1) are spun, cooled, drawn, and then deposited on the conveyor as a spunbond nonwoven web (14).

3. The method according to claim 1 or 2, wherein bicomponent filaments and / or multicomponent filaments are spun, and at least one component of the filaments is a polyolefin.

4. The method according to any one of claims 1 to 3, wherein bicomponent filaments and / or multicomponent filaments having a parallel configuration and / or an eccentric core-sheath configuration are spun.

5. The second suction air (23) is sucked from below through the conveyor between the area of the fiber deposition (18) and the area of the first hot air coupling device (7), and the wind speed (v ２ ) of the second suction air (23) is lower than the wind speed (v Ｍ ) of the main suction air (19), and the wind speed (v ２ ) of the second suction air (23) is higher than the wind speed (v １ ) of the first suction air (20). The method according to any one of claims 1 to 4.

6. After the first hot air bonding device (7) in the conveying direction of the nonwoven web (14), the nonwoven web (14) is bonded or pre-bonded by at least one second hot air bonding device (24), and second hot air (25) is blown by the second hot air bonding device (24). The method according to any one of claims 1 to 5.

7. The wind speed (v Ｈ１ of the first hot air (15) is higher than the wind speed (v Ｈ２ ) of the second hot air (25). The method according to claim 6.

8. The method according to claim 6 or 7, wherein the first hot air (15) has a higher air temperature than the second hot air (25).

9. The method according to any one of claims 6 to 8, wherein the first hot air bonding device (7) has a smaller air treatment area (26) than the second hot air bonding device (24) with respect to the nonwoven web (14) to be treated.

10. The third suction air (27) is suctioned from below through the conveyor in the area of the second hot air coupling device (24), and the wind speed (v ３ ) of the third suction air (27) is lower than the wind speed (v Ｈ２ ) of the second hot air (25). The method according to any one of claims 6 to 9.

11. The wind speed (v Ｍ of the main suction air (19) and the wind speed (v １ of the first suction air (20) are each higher than the wind speed (v ３ of the third suction air (27). The method according to claim 10

12. Fourth suction air (28) is sucked from below through the conveyor between the region of the first suction air (20) and the region of the third suction air (27), and the wind speed (v ４ ) of the fourth suction air (28) is lower than the wind speed (v １ ) of the first suction air (20), and the wind speed (v ４ ) of the fourth suction air (28) is higher than the wind speed (v ３ ) of the third suction air (27). The method according to claim 10 or 11.

13. The method according to any one of claims 6 to 12, wherein the temperature of the second hot air (25) is 80°C to 180°C.

14. The method according to any one of claims 6 to 13, wherein the first hot air bonding device (7) and / or the second hot air bonding device (24) are formed as a pre-bonding device for the nonwoven web (14), and after the pre-bonding in the conveying direction of the filaments, the nonwoven web (14) is finally solidified, particularly finally solidified by hot air.

15. The method according to any one of claims 1 to 14, wherein the conveying speed of the nonwoven web (14) exceeds 120 m / min.

16. The method according to any one of claims 1 to 15, wherein the nonwoven web (14) is produced by laminating two or more layers.

17. The nonwoven web (14) has a bulk density of 0.06 g / cm ３ Hereinafter, the method according to any one of claims 1 to 16, having a strength of 0.6 (N / 5 cm) / (g / m ２ ) or more.

18. An apparatus for producing a nonwoven fabric made of crimped synthetic continuous filaments for carrying out the method according to any one of claims 1 to 17, having a spinning device for spinning the fibers and comprising a cooling device (3) for cooling the fibers and a conveyor for depositing the fibers for the nonwoven web (14). A main suction area is installed immediately below the fiber deposition area (18), main suction air (19) can be sucked from below through the conveyor in the main suction area, and a first hot air bonding device (7) is installed downstream of the fiber deposition area (18) in the conveying direction of the conveyor or in the conveying direction of the nonwoven web (14) to act on the nonwoven web surface with the first hot air (15). A first suction air area is arranged immediately below the first hot air bonding device (7), and in the first suction air area, first suction air (20) is sucked from below through the conveyor and through the nonwoven web (14).

19. The apparatus according to claim 18, wherein the apparatus is designed as a spunbond apparatus for producing a nonwoven fabric from continuous filaments (1), and a stretching device (8) for stretching the filaments is arranged downstream of the cooling device (3) in the filament flow direction, and at least one diffuser (11) is arranged between the stretching device (8) and the conveyor.

20. The apparatus according to claim 19, wherein the assembly of the cooling device (3) and the stretching device (8) is formed as a closed unit, and the closed unit does not include the supply of air other than the supply of cooling air.

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