Method for producing a nonwoven composite web and apparatus for producing a nonwoven composite web

Abstract

Method (100a, 100b, 100c) for producing a composite nonwoven web (7) with at least two layers (1, 2, 3), wherein a first layer (1, 3) is formed by long fibers (4, 6) and a second layer (2) is formed by short fibers (5), wherein in a production line (9) the short fibers (5) are applied to the first layer (1, 3) in a wet-laying process (103) by a headbox (12) with a rotating or static turbulence generator.

Description

[0001] The invention relates to a method for producing a composite nonwoven web comprising at least two layers, wherein a first layer is formed by long fibers and a second layer is formed by short fibers. Furthermore, the invention relates to an apparatus for carrying out such a method.

[0002] Such composite nonwoven webs are used, for example, in the production of wet wipes. These types of wet wipes are used today in a variety of areas, including baby wipes, adult hygiene products, disinfectant wipes, and even cleaning wipes for surfaces, vehicles, and other products. Therefore, there are very different requirements not only with regard to quality but also with regard to the production costs of such wet wipes. For example, care wipes and hygiene products should be particularly soft and high-quality, making medium to high production costs acceptable. In contrast, wet wipes for cleaning purposes sometimes have significantly different requirements, primarily requiring low production costs.

[0003] Various such methods and devices for the production of composite nonwoven webs are known. Production usually takes place in a production line with several consecutively arranged devices that perform the individual work steps. Typically, each layer of fibers is successively formed into a web or applied to and bonded to it.

[0004] In most processes and devices, the second layer to be applied to the first layer is usually produced separately using a former and, in particular, as a pre-dewatered web with a dry content of generally more than 30%, is applied to the first layer, which is also a web and / or consists of long fibers, such as continuous spunbond-type threads. This is usually done in a dry or air process. Another well-known headbox is the inclined-wire headbox. Using such an inclined-wire headbox, an advantageous, wide-area distribution of the individual short fibers and, consequently, a particularly high degree of fiber entanglement can be achieved.

[0005] However, such inclined screen headboxes are relatively complex and expensive to construct, require a relatively large amount of space and are therefore relatively cost-intensive to manufacture, assemble and operate.

[0006] It should also be noted that in the present case, the term long fiber is understood to mean, in particular, a fiber that is relatively long compared to the short fiber, in particular a man-made and / or synthetic fiber. Such long fibers can, for example, have a length between 10 and 150 mm, particularly preferably between 30 and 40 mm. Alternatively, continuous filaments can also be provided as long fibers, as in the case of spunbond-type threads. The term short fiber is understood to mean, in particular, a fiber that is relatively short compared to the long fiber. Such short fibers can, for example, have a length between 0.2 and 9 mm. In particular, the second layer can be formed from an aqueous dispersion comprising dispersed natural fibers, recycled fibers such as waste paper, artificially produced fibers, and mixtures of such fibers. Therefore, when short fibers are mentioned below, this can also be understood to mean an aqueous dispersion comprising the short fibers.

[0007] The object of the present invention is therefore to improve the production of a composite nonwoven web to eliminate at least one of the above-mentioned disadvantages, in particular to reduce the production costs of such a web.

[0008] The invention solves the stated problem by a method having the features of claim 1, by a method of claim 2 and by a device having the features of claim 10 and a device having the features of claim 11. Advantageous embodiments and further developments of the invention are disclosed in the subclaims, the description and the figures.

[0009] The method according to the invention is a method for producing a composite nonwoven web with at least two layers, wherein a first layer is formed by long fibers and a second layer by short fibers. In a production line, the short fibers are laid through a headbox with a circular or cross-flow distributor and a rotating or static turbulence generator to form the second layer. The second layer is applied to the first layer. Before the second layer is applied, the short fibers are dispersed to form an aqueous dispersion. After the aqueous dispersion is applied to the first layer, water is removed from the resulting second layer by a screen belt and water is absorbed underneath by actively pumping or suctioning on the underside of the screen belt in order to apply an additional force component to the second layer that acts towards the first layer.Subsequently, a first hydroentanglement of the layers takes place while they are in contact with the screen belt, followed by a second hydroentanglement while they are in contact with a drum. Alternatively, after the aqueous dispersion has been applied to the first layer, water is extracted from the resulting second layer by a first screen belt, and the water is absorbed underneath by actively pumping or sucking in water from the underside of the first screen belt in order to apply an additional force component to the second layer, acting towards the first layer. Subsequently, a first hydroentanglement of the layers takes place while they are in contact with a second screen belt, followed by a second hydroentanglement while they are in contact with a drum.

[0010] A further object for solving the problem stated above is a method for producing composite nonwoven webs. The method provides that, in a production line, the short fibers are applied to the first layer in a wet-laying process through a headbox with a circular or cross-flow distributor in combination with a rotating and / or static turbulence generator. Such a headbox can, for example, be a so-called perforated roll headbox. In this case, the perforated roll, in particular, can form a rotating turbulence generator. Alternatively, the headbox can have a static turbulence generator, in particular a diffuser block.It has surprisingly been found that, in particular by arranging such a headbox with a rotating or static turbulence generator, in particular a perforated roller headbox, the production of the second layer, in particular the application of a second layer to the first layer, can be carried out in a particularly simple and efficient manner, so that the production of the composite nonwoven web can be carried out particularly cost-effectively. The headbox with a rotating turbulence generator can for this purpose be designed in particular as an open headbox. In this case, the short fibers to be applied, in particular an aqueous dispersion comprising the short fibers, can be applied to the first layer via an outlet gap, wherein the first layer is preferably transported continuously in a conveying direction below the headbox, in particular the perforated roller headbox.Alternatively, a closed headbox can be provided, in particular with a static turbulence generator, which allows higher speeds to be achieved. It has surprisingly been found that a rotating turbulence generator is particularly suitable for use in the process according to the invention at production speeds of up to 100 m / min, and a static turbulence generator at production speeds above 100 m / min. Furthermore, the headbox can be flowed onto from one side. The basis weight of the first layer can be between 10 and 80 g / m2. As it passes through the headbox, the first layer is particularly preferably transported on a screen belt, furthermore preferably on its surface, so that excess water in the dispersion of the second layer can be removed immediately below and / or in the direction of production after the headbox. This can be done, for example, by suction.After the second layer is applied, wet bonding can occur, for example, also on a screen belt or on a cylinder or drum. For the resulting composite nonwoven webs, the first layer can comprise between 20 and 80 percent by weight of the composite material. Accordingly, the second layer can also comprise between 20 and 80 percent by weight of the composite material.

[0011] Surprisingly, it has been found that with the method according to the invention at least one first layer with a basis weight between 10 g / m 2 and 80 g / m 2 and at least one second layer with a basis weight between 5 and 100 g / m 2 can be brought together to form the composite nonwoven web in a very wide production speed range from 50 m / min up to 500 m / min, if the lower edge of the outlet gap of the headbox of the wet-laying process is between a height level of the screen belt and a height level up to 150 mm above the screen belt and / or at a delivery angle of -20° to +20° to the direction perpendicular to the surface of the screen belt. This is because by changing the height level and / or the delivery angle, for example, the local area in which the second layer is applied to the first layer and the impulse or force introduced into the first layer can be varied.The energy introduced here can be adapted to the respective process conditions and the first and second layers in such a way that the composite nonwoven fiber web produced by the process according to the invention has particularly uniform properties. In particular, the height level and discharge angle of the wet-laying process can be adjusted in such a way that a structural change in the first layer due to the impact of the second layer is prevented.

[0012] According to the invention, additional water from the dispersion is extracted in the direction of production after the wet-laying process in order to apply an additional force component to the second layer, acting toward the first layer. This extraction takes place below the screen belt, for example, using vacuum suction devices, foil strips, or similar extraction devices, which preferably enable uniform extraction of water transversely to the direction of production. These extraction devices can preferably be varied with regard to the height of their extraction and the angle of the extraction, each relative to the screen belt. Furthermore, these dewatering devices can also be varied with regard to their distance from the stock outlet in the machine direction.Furthermore, the suction devices can preferably be designed as gravity drainers, in which only gravity acts on the water, or as vacuum drainers, which suck the water with a negative pressure of up to 800 mbar absolute pressure.

[0013] The first layer may comprise a single layer of long fibers produced in a single process step.

[0014] However, the first layer may also comprise two or more layers of long fibers produced in two or more separate process steps and subsequently bonded together. For example, the first layer may comprise a first layer produced using a first carding process and a second layer applied to and bonded to the first layer using a second carding process.

[0015] Likewise, the short fibers forming the second layer can be applied to the first layer in a single layer or in two or more layers.

[0016] During the wet-laying process, the short fibers preferably pass through a gap in the headbox. This gap can, in particular, be formed or limited at least partially by a perforated roller. This enables a particularly simple and wide-area distribution of the short fibers.

[0017] Preferably, the first layer is produced by unwinding a nonwoven web or by a carding process before the second layer is applied. This allows a particularly high strength of the composite nonwoven to be achieved. Carding of the first layer can, in particular, take place immediately before the second layer is applied, in particular online in the same production line. The first layer can therefore, in particular, be a carded nonwoven.

[0018] If the first layer comprises several layers, for example, two, each can comprise a carded web. Each of these layers is then referred to as a carded web ("C"). If the composite nonwoven web comprises a single second layer, also referred to as pulp ("P"), the composite nonwoven web would also be referred to as a "CCP."

[0019] It is also conceivable and within the scope of the invention to produce one layer of the first ply by a carding process, i.e., to form a card, and to produce a second layer of the first ply by a spunbond process, which is then correspondingly designated "S." Therefore, processes for producing composite nonwoven webs, for example, of a "CSP", "SCP", or "SSP" type, are also encompassed by the invention.

[0020] Preferably, the first layer is pre-consolidated—particularly immediately—before applying the second layer. Pre-consolidation can be carried out, in particular, on a screen belt. Pre-consolidation is carried out, in particular, by a water jet. For this purpose, a hydrodynamic needling or swirling process known per se for this application, in particular a water jet, can be used.

[0021] Preferably, the short fibers are dispersed to form an aqueous dispersion prior to applying the second layer. This dispersion can impart plastic properties to the fibers over the course of several minutes, thereby optimizing the efficiency of entanglement by water jets when the dispersion is applied to the first layer.

[0022] Preferably, at least one compaction of the at least two layers takes place—particularly immediately—after the second layer has been applied. In this case, water can be removed from the second layer at the same time, in particular by filtering off the excess water through the lower layer. Furthermore, a step of entangling the natural fibers of the second layer takes place using a water jet device. The entangling of the fibers takes place on a screen belt. For this purpose, a water nozzle known per se for this application can be used.

[0023] According to the invention, after the application of the second layer - in particular immediately after compaction - at least one entanglement of the short fibers of the second layer - particularly preferably exclusively - with each other and / or with the long fibers of the first layer takes place by means of hydroentanglement.

[0024] The hydroentanglement can occur when the at least one layer is resting on a screen belt or when at least one layer is resting against a drum. According to a first alternative, the invention provides for a first hydroentanglement of the layers to occur when the layers are resting against a screen belt, followed by a second hydroentanglement when the layers are resting against a drum. For this and all of the hydroentanglements mentioned below, a water nozzle known per se for this application can be used.

[0025] Surprisingly, it has been found that a further development of the method according to the invention for producing a composite nonwoven web, the first layer of which comprises only one or more C layers and the second layer of which comprises one or more P layers, is also particularly suitable for production speeds of more than 100 m / min and for basis weights of the first layer of 25 g / m 2 or less, if it comprises the following process steps: Carding and / or pre-consolidation of the first layer, moistening and fixing the first layer on a screen belt, as well as bringing together the first and second layers and initial hydrodynamic consolidation of both layers before transferring the two layers to further process steps. Preferably, after application of the second layer—in particular after hydroentanglement—the resulting composite nonwoven web is at least dried and subsequently rolled up.

[0026] Preferably, the first layer forms a lower layer and the second layer an upper layer, or the second layer forms a middle layer and the first layer each forms an upper and a lower layer. In the latter embodiment, the second layer, i.e. the short fibers, is arranged in particular between the two first layers, i.e. the long fibers. It should be clear here that the upper layer and the lower layer do not necessarily have to be of the same type, and in particular do not have to be the same layer at an earlier stage. Rather, the upper first layer and the lower first layer can be constructed differently and, in particular, manufactured separately.

[0027] The long fibers can be selected from the group of artificial and / or synthetic fibers, in particular from viscose, polyester, polypropylene, polyamide, polyacrylic, polyvinyl alcohol, and polyethylene fibers, as such or as a mixture. Natural fibers can also be used, for example selected from the group of cotton, hemp, flax, jute, or bamboo fibers, as such or as a mixture, including with those from the group of artificial and / or synthetic fibers. Furthermore, fibers made from biopolymers, e.g., polylactide or polyhydroxybutyrate https: / / de.wikipedia.org / wiki / Polyhydroxybutyrat, can also be used, as such or as a mixture, including with those from the group of artificial and / or synthetic fibers and / or natural fibers.

[0028] Particularly preferably, the concentration of short fibers in the headbox with rotating or static turbulence generator is between 0.5 and 10 grams / liter.

[0029] Preferably, the pre-consolidation of the first layer, the wet-laying process of the second layer and the compression of the at least two layers on a common, first screen belt, and then a hydroentanglement - in a first embodiment of the invention also exclusively - take place when the layers are in contact with a drum.

[0030] In a further embodiment of the invention, the first layer is pre-consolidated, the second layer is wet-laid, and the at least two layers are compressed on a first screen belt. Subsequently, a first hydroentanglement occurs while the layers rest on the first screen belt or on a separately formed second screen belt, and a second hydroentanglement occurs while the layers rest on a drum. In the latter embodiment, in which the first hydroentanglement occurs on the separately formed second screen belt and the second hydroentanglement occurs on a drum, one advantage lies in the process-technical decoupling of the wet-laid process from the hydroentanglement process.

[0031] The characteristics of forming and hydroentanglement fabrics can differ significantly. By separating these two steps, the process can be made more energy-efficient, particularly with less water and fiber loss, and more precisely controllable. In particular, the separation of the water circuits, especially those of the forming and hydroentanglement sections, enables individual operation of each circuit depending on requirements.

[0032] In a further embodiment of the invention, in particular for producing a three-layer composite nonwoven web, after the second layer has been applied to the first layer, in particular after compressing the two layers and in particular before hydroentanglement, an additional first layer is applied to the second layer by means of additional carding or unwinding a roll web. The second carding unit or unwinding device required for this purpose is integrated into the production line. This allows the second first layer to be applied continuously to the layers already produced. In this way, it is possible to produce composite nonwoven webs, for example with a CPC, SPC, or SPS structure.

[0033] Alternatively, an embodiment of the method according to the invention may be mentioned in which the first layer is produced by a carding process, i.e., formed as a C-layer. The C-layer may consist of bicomponent fibers or comprise bicomponent fibers. Bicomponent fibers are fibers in which at least one component has thermoplastic properties. The C-layer may also consist of monocomponent fibers, at least some of which have thermoplastic properties.

[0034] The carding process preferably includes an air bonding step before the second layer is applied to the first layer in a further step. During air bonding, the fibers of the first layer are exposed to heated air in such a way that the fibers fuse / bond together, at least partially, in areas where they are adjacent to one another.

[0035] The further process step preferably comprises a hydroentanglement for compacting and / or bonding the second layer to the first layer.

[0036] The process steps of carding, in particular air bonding, and compacting and bonding, in particular hydroentangling, can be carried out inline, i.e. in a common production line.

[0037] However, it is also possible to perform the two aforementioned process steps offline, i.e., in separate production lines. In this case, the first layer can be produced, for example, by means of through-bonding, rolled up, transported, and then unwound for application of the second layer. This process enables the production of particularly thick and highly absorbent, two-layer composite nonwoven webs, which are particularly suitable for the production of hygiene products.

[0038] The device according to the invention for producing a composite nonwoven web is characterized in that at least one conveyor device for transporting at least the first layer in a conveying direction and a headbox arranged above this conveyor device with a rotating and / or static turbulence generator, in particular a perforated roller headbox or headbox with a diffuser block, for applying the short fibers or dispersion of short fibers to the first layer to produce the second layer are arranged in a production line. By arranging such a headbox, the production costs of such a web can be significantly reduced. In particular, a relatively space-saving system can be provided that is relatively cost-effective both in terms of production and assembly, as well as in operation.By arranging the headbox above the conveyor, liquid can be removed from the second layer immediately below the headbox, in particular by dewatering the carded and pre-consolidated long fiber layer, and thereby returned to the headbox in a particularly effective manner in a cycle. The conveyor is particularly designed such that the composite nonwoven fabric strip can be transported from the beginning of the production line to the end of the production line. For this purpose, the device can comprise several conveying devices, such as conveyor belts, drive rollers, deflection rollers, embossing rollers and / or drums. The conveyor in question here, above which the headbox is arranged, can be designed, for example, as a screen belt.

[0039] According to the invention, water is removed from the resulting second layer in the conveying direction downstream of the headbox by a screen belt and a water intake located underneath it, by actively pumping or sucking in the water from the underside of the screen belt. A first hydroentanglement device for intertwining the short fibers of the second layer with each other and a second hydroentanglement device for intertwining the short fibers of the second layer with the long fibers of the first layer are arranged downstream.

[0040] Preferably, one or more carding units, preferably with rotating or static turbulence generators, are arranged upstream and / or downstream of the headbox in the conveying direction to produce the first layer. This allows the first layer to be designed, in particular, as a carded nonwoven.

[0041] The conveying device preferably comprises a first screen belt, with the headbox preferably being arranged above this first screen belt. The first screen belt can, in particular, be designed as a forming screen. The first screen belt serves, in particular, to ensure particularly effective dewatering of the suspension through the screen support. Furthermore, this can improve the overall water balance of the plant and consequently reduce the costs associated with operating the plant.

[0042] Preferably, the first screen belt extends with a section both below the headbox and below at least one hydroentanglement device.

[0043] In one embodiment of the device according to the invention, which is particularly suitable for producing a composite nonwoven web whose first layer comprises only one or more C layers and whose second layer comprises one or more P layers, even for production speeds of more than 100 m / min and for basis weights of the first layer of 25 g / m 2 or more, a first screen belt is provided downstream of the headbox in the conveying direction, on which pre-consolidation, moistening and fixing of the first layer takes place. Downstream in the production direction, a second screen belt is provided, on which the first and second layers are brought together and an initial hydrodynamic consolidation of both layers takes place before the two layers are transferred to further process steps.

[0044] In another embodiment of the invention, a second water jet device for compacting at least the first and second layers, a first hydroentanglement device for intertwining the short fibers of the second layer, and / or a second hydroentanglement device for intertwining the short fibers of the second layer with the long fibers of the first layer are arranged downstream of the headbox in the conveying direction. Preferably, the second water jet device for compacting the layers is arranged above a first conveyor for transporting the material web, such as the first screen belt, and the first hydroentanglement device is arranged above a separate second conveyor for transporting the material web, such as a second screen belt.This makes it possible, in particular, to decouple the formation of the layers and their hydroentanglement, so that both parts of the system can be controlled separately and thus more precisely and consequently operated more efficiently.

[0045] The headbox preferably comprises a turbulence generator in the form of perforated rollers or diffusers. In an alternative embodiment, such a turbulence generator is not provided.

[0046] A further object for solving the problem posed at the outset is a device for carrying out the method according to the invention.

[0047] Four exemplary embodiments of the invention are explained in more detail below with reference to the figures. Like reference numerals denote like components. They show schematically: Figure 1 - a first embodiment of the device according to the invention; Figure 2- a flow chart of a first embodiment of the method according to the invention with the device according to Fig.1 ; Figure 3 - a second embodiment of the device according to the invention; Figure 4 - a third embodiment of the device according to the invention; Figure 5 - a flow chart of a second embodiment of the method according to the invention with the device according to Fig. 3 or Fig.4 ; Figure 6 - a fourth embodiment of the device according to the invention; Figure 7 - a flow chart of a third method according to the invention with the device according to Fig.6 ; Figure 8 - a supply system for one of the aforementioned devices; and Figure 9 - a flow chart of the system according to Fig.8 .

[0048] The Figure 1 , 3 , 4 and 6 devices 30a, 30b, 30c and 30d shown as well as those shown in the Figure 2 , 5 and 7The methods 100a, 100b, 100c shown serve in particular to produce a composite nonwoven web 7 with at least two layers 1, 2, 3, wherein a first layer 1, 3 is formed by long fibers 4, 6 and a second layer 2 is formed by short fibers 5.

[0049] In the Figure 1 a first embodiment of the device 30a according to the invention is shown, with which a Figure 2 illustrated first embodiment of the method 100a according to the invention can be operated.

[0050] The device 30a comprises a production line 9, which, viewed in a conveying direction 8, has a first region 31 for forming the first layer 1, a second region 32 for forming the second layer 2, a third region 34 for consolidating the two layers 1, 2, and a fourth region 35 for finishing the web 7. The web 7 is transported from the first region 31 to the fourth region 35 by means of a conveyor device 27 (not shown in full).

[0051] In the first region 31, a carding unit 10 is provided for producing, in particular carding 101, the first layer 1.

[0052] The second area 32 comprises a pre-consolidation unit 11, a headbox 12 with a rotating or static turbulence generator, in particular a perforated roller headbox, and a compression unit 13. Furthermore, in this second area 32, as part of the conveyor device 27, a circulating screen belt 21 for transporting the web 7 and a water intake 20 are arranged.

[0053] The pre-consolidation unit 11 comprises a first water jet device for pre-consolidating 102 the first layer 1.

[0054] The headbox 12 comprises a cross-flow or circular flow distributor 23 and a unit, such as a storage tank, that provides the short fibers 5 or an aqueous dispersion 5a comprising the short fibers 5. The headbox 12 is used for the application 103 of the second layer 2 to the first layer 1, also referred to as wet laying.

[0055] The compression unit 13 in the present case comprises a second water jet device for compressing 104 at least the applied second layer 2. Below the pre-consolidation unit 11, the headbox 12 and / or the compression unit 13, the water intake 20 is arranged for at least partially dewatering the second layer 2 applied to the first layer 1, in particular for filtering off the excess water through the lower layer.

[0056] In the third area 34, a consolidation unit 16, in particular a hydroentanglement device for hydroentanglement 107 of the two layers 1, 2, is arranged. The hydroentanglement 107 takes place in particular on both flat sides of the web 7. For this purpose, the web 7 rotates around a first drum 24 and a second drum 25. Furthermore, a finishing unit 17 is arranged in the third area 34, in particular a further hydroentanglement device for one-sided forming or embossing 108 of the web 7. A third drum 26 is provided for this purpose.

[0057] In the fourth area 35, the web 7 is dried 109 by means of a drying drum 18 and the web 7 is rolled up 110 onto a winding roll 19.

[0058] In the Figure 3 is a second embodiment of the device 30b according to the invention and in Figure 4a third embodiment of the device 30c according to the invention is shown, wherein with both devices 30b, 30c each one in Figure 5 illustrated second embodiment of the method 100b according to the invention can be operated.

[0059] The device 30b, 30c in turn each comprises a production line 9, which, viewed in a conveying direction 8, has a first region 31 for forming the first layer 1, a second region 32 for forming the second layer 2, a third region 34 for consolidating the two layers 1, 2, and a fourth region 35 for finishing the web 7. The web 7 is transported from the first region 31 to the fourth region 35 by means of a conveyor device 27 (not shown in full). The devices 30b, 30c differ in particular in the arrangement and design of the conveyor device in the second and third regions 32, 34.

[0060] In the first region 31 of the devices 30b, 30c, a carding unit 10 is provided for producing, in particular carding 101, the first layer 1.

[0061] The second area 32 comprises a pre-consolidation unit 11, again a headbox 12 with a rotating or static turbulence generator, and a compression unit 13. The pre-consolidation unit 11 here comprises a first water jet device for pre-consolidating 102 the first layer 1. The headbox 12 here comprises a cross-flow or circular flow distributor 23 and a unit, such as a storage tank, that provides the short fibers 5 or an aqueous dispersion 5a comprising the short fibers 5. The headbox 12 is used to apply 103 the second layer 2 to the first layer 1. The compression unit 13 comprises a second water jet device for compressing 104 at least the applied second layer 2.

[0062] In the third area 34, a first consolidation unit 15, in particular a first hydroentanglement device for hydroentanglement 106, in particular of the second layer 2, and a second consolidation unit 16, in particular a hydroentanglement device for hydroentanglement 107 of the two layers 1, 2 are arranged. The hydroentanglement 107 takes place, in particular, exclusively on the upper flat side of the web 7, i.e., exclusively on the second layer 2. For this purpose, the web 7 rests on a conveyor device 27. The hydroentanglement 107 in turn takes place on both flat sides of the web 7. For this purpose, the web 7 rotates around a first drum 24 and a second drum 25. Furthermore, a forming unit 17 is arranged in the third area 34, in particular a further hydroentanglement device for one-sided forming or embossing 108 of the web 7. A third drum 26 is provided for this purpose.

[0063] At the Figure 3In the device 30b shown, a first screen belt 21 is arranged as a component of the conveyor device 27 for transporting the web 7 in the second region 32, and a separately formed second screen belt 22 is arranged in the third region 34. The first screen belt 21 transports the web 7 up to behind the compression unit 13. In the region of the first screen belt 21, the steps of pre-consolidation 102, wet-laying 103, and compression 104 therefore again take place. The second screen belt 22, which takes over the web 7 after compression 104, transports the web 7 exclusively in the region of the first consolidation device 15. In the region of the second screen belt 22, the step of hydroentanglement 106 therefore takes place exclusively.This separation of the two conveying sections in the area of ​​the first screen belt 21 and the second screen belt 22 enables particularly precise control and regulation of the system, in particular with regard to the water removal from the second layer 2, and thus particularly efficient operation, particularly when using a headbox 12 with a rotating or static turbulence generator.

[0064] At the Figure 4In contrast, the device 30c shown includes a screen belt 21 extending over the second region 32 and partially over the third region 34, in particular also below the first solidifying device 15. A separately formed second screen belt 22 is not provided in this device 30c. This configuration offers advantages with regard to manufacturing and operating costs, particularly due to the smaller number of components, in particular the drive and control components, compared to the device 30b.

[0065] Common to both devices 30b and 30c is again the fourth area 35, in which drying 109 of the web 7 by means of a dryer drum 18 and rolling 110 of the web 7 onto a winding roll 19 takes place.

[0066] In the Figure 6 a fourth embodiment of the device 30d according to the invention is shown, with which a Figure 7illustrated third embodiment of the method 100c according to the invention can be operated.

[0067] The device 30d comprises a production line 9, which, viewed in a conveying direction 8, has a first region 31 for forming the first layer 1, a second region 32 for forming the second layer 2, a third region 33 for forming an additional second first layer 3, a fourth region 34 for consolidating the three layers 1, 2, 3, and a fifth region 35 for finishing the web 7. The web 7 is transported from the first region 31 to the fifth region 35 by means of a conveyor device 27 (not shown in full). The device 30d differs from the Figure 1 shown device 30a in particular in the arrangement of a further carding unit 14 for carding 105 a further layer 3.

[0068] In the first region 31, a first carding unit 10 is provided for producing, in particular carding 101, the first layer 1.

[0069] The second area 32 comprises a pre-consolidation unit 11, again a headbox 12 with rotating or static turbulence generator and a compression unit 13. The pre-consolidation unit 11 in turn comprises a first water jet device for pre-consolidating 102 the first layer 1. The headbox 12 comprises a cross-flow or circular flow distributor 23 and a unit providing the short fibers 5 or an aqueous dispersion 5a comprising the short fibers 5, such as a storage tank. The headbox 12 is used to apply 103 the second layer 2 to the carded first layer 1. The compression unit 13 comprises a second water jet device for compressing 104 at least the applied second layer 2. Below the pre-consolidation unit 11, the headbox 12 and / or the compression unit 13, the screen belt 21 and the water intake 20 are arranged for at least partially dewatering the second layer 2 applied to the first layer 1.

[0070] In the third region 33, the second carding unit 14 is arranged for carding 105 a further first layer 3. This additional first layer 3 also comprises long fibers 6, which, however, do not necessarily have to correspond to the long fibers 4 of the first layer 1 produced by the first carding unit 10. This additional first layer 3 results in a three-layer composite nonwoven fabric in which the outer flat sides are each formed by a first layer 1, 3, and the second layer 2 is arranged between the two first layers.

[0071] In the fourth region 34, a consolidation unit 16, in particular a hydroentanglement device for hydroentanglement 107 of the three layers 1, 2, 3, is arranged. The hydroentanglement 107 takes place in particular on the two outer flat sides of the web 7. For this purpose, the web 7 rotates around a first drum 24 and a second drum 25. Furthermore, a forming unit 17 is arranged in the third region 34, in particular a further hydroentanglement device for one-sided forming or embossing 108 of the web 7. A third drum 26 is provided for this purpose.

[0072] In the fifth area 35, the web 7 is dried 109 by means of a drying drum 18 and the web 7 is rolled up 110 onto a winding roll 19.

[0073] In the Figure 8 an example of a supply system 121 is shown, in particular a water management system, with which the Figure 9illustrated embodiment of a method 100d can be operated.

[0074] The supply system 121 is concerned, on the one hand, with the provision of an aqueous dispersion 5a comprising the short fibers 5 for the headbox 12 and, on the other hand, with the provision, use and recirculation of water provided for in the aforementioned context.

[0075] To produce the aqueous dispersion 5a, short fibers 5 are first conveyed by means of a bundle conveyor 113 to a dispersing unit 114 for dispersion 111 therein. The resulting purified mass is fed by a pump 115 to a mixer and / or container 116 for storage 112. Provision to the headbox 12 is achieved by pumping 117 the dispersion 5a from the container 116. After application 103 of the dispersion 5a via the roller 23 to the first layer 1, water can be removed from the resulting second layer 2 by the screen belt 21 and the water absorption 20 located underneath. In particular, active pumping or suction 118 can take place on the underside of the screen belt 21. This allows liquid to be removed from the second layer 2 particularly effectively. The water obtained by the water intake 20 is fed to a water tank 119.From this water tank 119, water can be supplied by a pump 120 to the headbox 12, the container 116, a conveying line for pumping 117 the dispersion 5a from the container 116, and / or a conveying line for pumping 115 the slurry from the dispersing unit 114. The last two options serve in particular to prevent blockages during pumping 115, 117. This water circuit enables particularly efficient and cost-effective operation of the system.

[0076] It should be clear that the scope of the present invention is not limited to the described embodiments. In particular, components of one example may also be implemented in another example. In particular, the structure and arrangement of the production line in the areas upstream and downstream of the headbox with rotating or static turbulence generator may be modified without altering the essence of the invention. List of Bezuas characters:

[0077] 1First layer 2Second layer 3First layer 4Long fiber 5Short fiber 6Long fiber 7Fabric web 8Conveyor direction 9Production line 10First carding unit 11Pre-consolidation unit, first water jet device 12Headbox 13Compression unit, second water jet device 14Second carding unit 15Consolidation unit, first water jet entanglement device 16Consolidation unit, second water jet entanglement device 17Forming unit, third water jet entanglement device 18Dryer drum 19Winding roll 20Water intake 21First screen belt 22Second screen belt 23Cross or circular flow distributor 24First drum 25Second drum 26Third drum 27Conveyor device 30aDevice 30bDevice 30cDevice 30dDevice 100aProcess 100bProcess 100cProcess 101Carding 102Pre-consolidation 103Applying, wet-laying 104Compressing 105Carding 106Hydroentanglement 107Hydroentanglement 108Hydroentanglement 109Drying 110Reeling 111Dispersing 112Storage 113Bundle conveyor 114Dispersing unit 115Pumping 116Storage 117Pumping 118Pumping 119Water tank 120Pumping 121Supply system

Claims

1. A method (100a, 100b, 100c, 100d) for producing a composite nonwoven web (7) having at least two layers (1, 2, 3), wherein a first layer (1, 3) is formed by long fibers (4, 6) and a second layer (2) is formed by short fibers (5), characterized in thatin a production line (9) the short fibers (5) are laid to the second layer (2) through a headbox (12) with a circular or cross-flow distributor and with a rotating or static turbulence generator, that the second layer (2) is applied to the first layer (1), that before the application (103) of the second layer (2) a dispersion (111, 112) of the short fibers (5) takes place to form an aqueous dispersion (5a), and that after the application (103) of the aqueous dispersion (5a) to the first layer (1) a water extraction from the resulting second layer (2) by a sieve belt (21) and a water absorption (20) located underneath by an active pumping orSuction (118) takes place on the underside of the screen belt (21) in order to apply an additional force component to the second layer (2) acting towards the first layer (1), wherein a first hydroentanglement (15) of the layers (1, 2) then takes place when they rest on the screen belt (21) and a subsequent second hydroentanglement (16) takes place when they rest on a drum (24), or that after the application (103) of the aqueous dispersion (5a) to the first layer (1), water is removed from the resulting second layer (2) by a first screen belt (21) and a water absorption (20) located underneath it by an active pumping out orSuction (118) is carried out on the underside of the first screen belt (21) in order to apply an additional force component to the second layer (2) acting towards the first layer (1), and then a first hydroentanglement (15) of the layers (1, 2) is carried out when they rest on a second screen belt (22) and a downstream second hydroentanglement (16) is carried out when they rest on a drum (24).

2. Method (100a, 100b, 100c, 100d) for producing a composite nonwoven web (7) with at least two layers (1, 2, 3), wherein a first layer (1, 3) is formed by long fibers (4, 6) and a second layer (2) is formed by short fibers (5), characterized in thatin a production line (9) the short fibers (5) are applied to the first layer (1, 3) through a headbox (12) with a circular or cross-flow distributor and with a rotating or static turbulence generator, that before the application (103) of the second layer (2) a dispersion (111, 112) of the short fibers (5) takes place to form an aqueous dispersion (5a), and that after the application (103) of the aqueous dispersion (5a) to the first layer (1) a water extraction from the resulting second layer (2) by a sieve belt (21) and a water absorption (20) located underneath by an active pumping orSuction (118) takes place on the underside of the screen belt (21) in order to apply an additional force component to the second layer (2) acting towards the first layer (1), wherein a first hydroentanglement (15) of the layers (1, 2) then takes place when they rest on the screen belt (21) and a subsequent second hydroentanglement (16) takes place when they rest on a drum (24), or that after the application (103) of the aqueous dispersion (5a) to the first layer (1), water is removed from the resulting second layer (2) by a first screen belt (21) and a water absorption (20) located underneath it by an active pumping out orSuction (118) is carried out on the underside of the first screen belt (21) in order to apply an additional force component to the second layer (2) acting towards the first layer (1), and then a first hydroentanglement (15) of the layers (1, 2) is carried out when they rest on a second screen belt (22) and a downstream second hydroentanglement (16) is carried out when they rest on a drum (24).

3. Method (100a, 100b, 100c, 100d) according to one of the preceding claims, characterized in that the first layer (1) forms a lower layer and the second layer (2) forms an upper layer, or the second layer (2) forms a middle layer and the first layer (1, 3) each forms an upper layer (1) and a lower layer (3).

4. Method (100a, 100b, 100c, 100d) according to one of the preceding claims, characterized in thatthe long fibers (4, 6) are selected from the group of artificial and / or synthetic fibers, in particular from viscose, polyester, polypropylene, polyamide, polyacrylic, polyvinyl alcohol and polyethylene fibers as such or as a mixture, or that the long fibers are selected from the group of cotton, hemp, flax, jute or bamboo fibers, as such or as a mixture, also with those from the group of artificial and / or synthetic fibers, or that the long fibers are selected from biopolymers, in particular based on polylactide or polyhydroxybutyrate, as such or as a mixture, also with those from the group of artificial and / or synthetic fibers and / or natural fibers.

5. Method (100a, 100b, 100c, 100d) according to one of the preceding claims, characterized in that the concentration of short fibers (5) in the headbox (103) is between 0.5 and 10 g / l.

6. Method (100a, 100b, 100c, 100d) according to one of the preceding claims, characterized in thatit comprises the following process steps: - carding and / or pre-consolidation of the first layer, - moistening and fixing of the first layer on a screen belt, and - bringing together the first and second layers and initial hydrodynamic consolidation of both layers before transferring the two layers to further process steps.

7. Method (100b) according to one of the preceding claims, characterized in thata pre-consolidation (102) of the first layer (1), the wet-laying process (103) and a compression (104) of the at least two layers (1, 2, 3) takes place on the first screen belt (21), and then a first hydroentanglement (106) takes place when the layers (1, 2, 3) lie on the first screen belt (21) or on the separately formed second screen belt (22), and the second hydroentanglement (107) takes place when the layers (1, 2, 3) lie on the drum (24, 24, 26), wherein the wet-laying process preferably takes place between a height level of the screen belt (21) and a height level up to 150 mm above the screen belt and / or at a discharge angle of -20° to +20° to the direction perpendicular to the surface of the screen belt (21).

8. Method (100a, 100b, 100c, 100d) according to one of the preceding claims, characterized in thatthe first layer is produced by a carding process and consists of two-component fibers or comprises two-component fibers, wherein the carding process preferably comprises an air bonding process step in which the fibers of the first layer are exposed to heated air before the second layer is applied to the first layer in a further process step, wherein the further process step preferably comprises hydroentanglement for compacting and / or bonding the second layer to the first layer.

9. Method (100c) according to one of the preceding claims, characterized in that after the application (103) of the second layer (2) to the first layer (1), an additional first layer (3) is applied to the second layer (2) by means of an additional carding (105).

10. Method (100a, 100b, 100c, 100d) according to one of the preceding claims, characterized in thatthe first layer (1) and / or the second layer (2) is made of a plurality of layers applied to one another.

11. Device for producing a composite nonwoven web (7) with at least two layers (1, 2, 3), wherein a first layer (1, 3) is formed by long fibers (4, 6) and a second layer (2) is formed by short fibers (5), characterized in that the device is configured to carry out a method according to one of the preceding claims.

12. Device (30a, 30b, 30c, 30d) for producing a composite nonwoven web (7) with at least two layers (1, 2, 3), wherein a first layer (1, 3) is formed by long fibers (4, 6) and a second layer (2) is formed by short fibers (5), characterized by thatin a production line (9) at least one conveyor device (21, 22, 27) for transporting at least the first layer (1) in a conveying direction (8) and a headbox (12) arranged above the conveyor device (21) with a rotating or static turbulence generator for applying (103) the short fibers (5) to the first layer (1) to produce the second layer (2) is arranged, and that a carding unit (10) for producing the first layer (1) is arranged preferably in the conveying direction (8) before and / or after the headbox (12), wherein in the conveying direction (8) after the headbox (12) by a screen belt (21) and a water intake (20) located underneath it by an active pumping orSuction (118) on the underside of the screen belt (21) results in water being removed from the resulting second layer (2), a first hydroentanglement device (15) is arranged for intertwining (106) the short fibers (5) of the second layer (2) with one another and a second hydroentanglement device (16) is arranged for intertwining (107) the short fibers (5) of the second layer (2) with the long fibers (4, 6) of the first layer (1, 3).

13. Device (30a, 30b, 30c, 30d) according to one of claims 11 to 12, characterized in thatthe conveying device (27) comprises a first screen belt (21), and the headbox (12) is arranged above the first screen belt (21), that preferably the headbox (12) is arranged and / or designed such that the wet laying process takes place between a height level of the screen belt (21) and a height level up to 150 mm above the screen belt (21) and / or at a discharge angle of -20° to +20° to the direction perpendicular to the surface of the screen belt (21), and that preferably the first screen belt (21) extends with a section both below the headbox (12) and below at least one water jet device (11, 13, 15).

14. Device (30a, 30b, 30c, 30d) according to claims 11 to 13, characterized in that in the conveying direction (8) after the headbox (12) a second water jet device (13) for compacting (104) at least a first layer (1) and a second layer (2).

15. Device (30a, 30b, 30c, 30d) according to one of claims 11 to 14, characterized in that the headbox (12) comprises a turbulence generator.

16. Device (30b) according to one of claims 11 to 15, characterized in that a first screening belt (21) and a second screening belt (22) behind it in the direction of production are provided.

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