EP3017105B1 - Method and device for manufacturing a nonwoven - Google Patents

Description

The present invention relates to a method and an apparatus for producing a nonwoven fabric.

A nonwoven web is a web of limited length fibers, continuous filaments or cut yarns of any kind and of any origin, which are in some way joined together to form a nonwoven (ie, a fibrous web) and somehow bonded together have been. Nonwoven fabrics include fiber webs made by interlacing yarns such as those used in weaving, knitting, knitting, lace making, braiding, and tufted fabric making. Also films and papers are not among the nonwovens.

WO2007 / 124966 A1 and DE102008054990 A1 each describe a device and a method having the features according to the preamble of the independent claims.

Known processes for the production of nonwovens generally include nonwoven formation, nonwoven bonding and subsequent dewatering. Different methods of web formation are, for example, in WO 2007/018960 A2 described. In this case, the nonwoven can be formed in particular by a dry process, a wet process and / or an extrusion process. Thus, for example, an at least partially aerodynamic web formation is known, in which the web is formed at least partially from fibers by means of an air flow on an air-permeable base. Alternatively, the fleece also be formed at least partially mechanically. In this case, the fleece can be formed, for example, from carding or carding removed flores, which are superimposed, or the fleece can also be formed directly from carding machines. According to another alternative can there Nonwoven also be formed at least partially by the so-called spunbond process, in which the nonwoven fabric is formed by depositing fibers which are spun from a passing through nozzle melt polymer melt and by means of cold air and / or mechanically drawn. Moreover, the web can also be formed, at least in part, by the so-called melt-blown process in which the web is formed by depositing fibers directly spun from a polymer melt passing through nozzles and drawn to rupture by means of hot air streams. In principle, any combinations of such web-forming methods are also conceivable.

The subsequent nonwoven consolidation can be done, for example, by the so-called hydroentanglement process - which is also called "spunlacing". In this case, the formed nonwoven is solidified by entanglement of the fibers, wherein the entangling is effected by swirling, in particular by acting on the nonwoven focused high-pressure water jets. Such hydroentanglement entails further physical and visible properties of the nonwoven fabric produced. After high pressure hydroentanglement, the nonwoven web is primarily passed over air suction slits to remove as much liquid as possible from the web before it is fed to the dryer section, in which further dewatering and in some cases so-called thermal and / or chemical solidification done.

During the application of suction air results in a non-uniform moisture cross profile of the material web, the web edges remain moister than the remaining material web.

For relatively heavy or non-woven fabrics made from different raw materials, the efficiency of the drainage is limited, resulting in a correspondingly greater energy requirement for the evaporation of the excess liquid and the machine speed is lowered. In addition, the drainage efficiency is limited especially for open and / or perforated nonwovens.

The usual drainage via air suction slots brings a number of disadvantages. Thus, the desired uniform moisture profile of the nonwoven fabric web is destroyed or at least impaired, which is particularly due to air losses at the web edges due to a non-constant width of the web. The air loss at the material web edges also brings a high energy consumption with it. Depending on the basis weight, nonwoven composition and structure of the nonwoven web, e.g. may also be structured or perforated, the dry content of the nonwoven web obtained after dewatering is limited. Due to the relatively high vacuum, loss may occur on the particular transfer belt which guides the nonwoven web over air suction slits, which is usually a cloth belt, forming fabric, or non-woven structuring and / or perforating structuring belt Fibers come through so-called "fiber plucking". The plucked fibers pollute the wastewater and are lost to the manufacturing process.

From the DE 10 2006 042 507 A1 For example, it is known to use a shoe press for dewatering a nonwoven web. Although such a shoe press, viewed in the web running direction, has an extended press nip or press nip, as compared to a nip. Due to the relatively high pressure of the shoe press, however, it comes before the press nip the shoe press to a disturbing water retention. In addition, the relatively high pressure of the shoe press leads to a reduction in the volume of the nonwoven fabric.

The invention is therefore based on the object to provide a method and an apparatus of the type mentioned, with which the aforementioned Problems are eliminated in the simplest and most reliable way possible. In particular, an efficient and cost-effective drainage of the formed nonwoven material web is to be achieved, which leads to a nonwoven material web with the largest possible volume and with a uniform moisture cross profile while avoiding a water jam. The structures and / or surface parameters produced during the web formation in the former are to be maintained in the course of the subsequent further dewatering of the material web, and the total product volume should as far as possible not be restricted by this further dewatering. A moisture profile which is as uniform as possible up to the web edges should be ensured, in particular, even with perforated nonwovens. While avoiding the use of air suction slits and a complex shoe press, the device is intended to ensure the highest possible dewatering capacity, as is required, in particular, to remove larger quantities of liquid introduced into the web, for example in the course of hydroentanglement, and to have as compact a structure as possible. In addition, the solution according to the invention should also be feasible by the simplest possible conversion of existing machines.

According to the invention this object is achieved by a method having the features of claim 1 and a device having the features of claim 8.

With regard to the method, the object is accordingly achieved, in particular, by methods for producing a nonwoven fabric in which a nonwoven is formed in a former and the resulting nonwoven material web is subsequently further dehydrated. In this case, the further dewatering of the nonwoven material web comprises the dewatering by means of a belt press, wherein the belt press has a roller to the - to form an elongated press nip or press nip - at least one applied to the roller inner band and an outer press belt - each in one certain wrapping angle - are looped, wherein the nonwoven material web at least in the region of the roller between the inner band and the outer press belt is arranged. The press belt is pressed onto the roll at a belt tension of at least 15 kN / m to create a mechanical pressure on the nonwoven web lying between the two belts, thereby pressing the nonwoven web and the inner belt contacting the roll against the roll to squeeze. In addition, the nonwoven fabric is formed in the former on a circulating transfer belt and the resulting nonwoven material web is passed over the transfer belt at least to the belt press and through its extended press nip. As with the transfer belt, the belts of the belt press are preferably revolving or endless belts, which are guided together with the nonwoven material web through the (extended) press nip of the belt press.

The device according to the invention provided in particular for carrying out the method according to the invention accordingly comprises a former for forming a nonwoven and a belt press for further dewatering of the nonwoven material web formed from the formed nonwoven. In this case, the belt press comprises a roller, around which at least one inner band lying against the roller and an outer pressing belt are wound. The nonwoven material web can be arranged and preferably arranged at least in the area of the roller between the inner band and the press belt. In this case, the press belt is pressed with a belt tension of at least 15 kN / m to the roller and preferably pressed. Furthermore, the nonwoven fabric is formed on a circulating transfer belt and the resulting nonwoven material web is guided over this transfer belt at least to the belt press and through its (extended) press nip.

For the purposes of the present invention, nonwoven is understood to mean a nonwoven fabric of low consistency obtained directly by the formation, whereas Nonwoven fabric is to be understood as meaning a nonwoven already having a certain or relatively higher consistency.

For the purposes of the present invention, belt tension of the outer press belt is understood to mean the quotient of the tension applied to the press belt and the width of the press belt, in accordance with the usual use of this term.

Further, in the context of the present invention, press nip is understood to mean the gap which is formed between the inner and outer band of the belt press by pressing the outer band against the roller with a belt tension of at least 15 kN / m.

Due to this embodiment of the method and the device results in a total more efficient, cost-effective drainage of the formed nonwoven material web, while avoiding the previously occurring especially in connection with a shoe press water accumulation before the press nip - in comparison to the use of a shoe press - a larger volume the produced nonwoven material web is achieved because the pressure in the extended press nip of the belt press is lower than in a shoe press. However, as a result of the longer residence time of the nonwoven material web in the nip compared to the use of a shoe press, efficient drainage with a high degree of dewatering is ensured despite the lower compacting pressure. Due to this, a thermal drying device, which may still be provided after the belt press, such as a TAD (Through Air Drying) or air drying device, requires only a very small amount of energy. In addition, in the invention due to the belt press used in comparison to the methods known from the prior art, a very gentle and - based on the surface of the nonwoven material web - very uniform drainage achieved, so that an impairment or even destruction of the fiber structure is reliably prevented. Due to this, fiber losses as well as contamination of the waste water are kept to a minimum. Moreover, with the method according to the invention or the device according to the invention, an improved moisture transverse profile for the nonwoven fabric formed is also obtained. Of particular advantage is in particular the relatively compact design of the device according to the invention, which, inter alia, results in the fact that the hitherto required air suction and expensive shoe press omitted. Moreover, the solution according to the invention is particularly easy to implement by a corresponding conversion of existing machines.

The invention also makes it possible to transfer the nonwoven material web with a higher solids content to the final, in particular thermal drying device, whereby the machinability in the dryer section is increased. Due to the reduced pressure in the belt press, the volume of the nonwoven web is reduced by no more than 10% in the dewatering. Thus, the solids content of the nonwoven web can be increased relative to the water content compared to the usual dewatering over air suction slots by more than 10%, resulting in a higher production capacity, energy consumption is reduced and the provision of additional or more expensive drying facilities is avoided.

By the nonwoven fabric formed on a circulating transfer belt and the resulting nonwoven material web is passed over this transfer belt at least up to the belt press and through its extended press nip, wherein the web at least until after the press nip the belt press preferably in a closed train on the transfer belt is guided, the inventive method in particular an excellent Maschinengängigkeit. In addition, this is a deterioration of the quality of the formed nonwoven fabric due to an open draw, in particular an undesirable Elongation of the nonwoven web and / or the formation of unwanted fractures in the nonwoven web, reliably avoided, especially when the nonwoven web is passed through the device at a high speed. In the method according to the invention, the nonwoven material web is preferably guided in a closed loop from the former via the belt press to a thermal drying device arranged downstream of the belt press.

According to the present invention, the formed web is also solidified on the transfer belt before being transferred to the belt press. In this embodiment, solidification of the formed web preferably comprises consolidation by the hydroentanglement process.

Further, it is preferred that the nonwoven web be fed downstream of the belt press by a thermal dryer, most preferably a through-air drying (TAD), to deliver the nonwoven web to the desired final dry content dry.

As the thermal drying device, preferably no more than one TAD or air drying device is used in the above embodiment, in particular with only a single TAD drying cylinder. The diameter of such a TAD drying cylinder is advantageously less than 4 m, preferably less than 3.5 m and particularly preferably less than 3 m.

In order to achieve the above-mentioned advantages with respect to the web guide in a closed train to a particularly high degree, it is particularly preferred in the above embodiment, when the nonwoven material web through the transfer belt over the belt press out to the thermal drying device and is passed therethrough.

According to another most preferred embodiment of the present invention, bands of the belt press are used against drying fluid and preferably air and / or water vapor permeable belts, and simultaneously with the pressing of the nonwoven web against the roller becomes a drying fluid through the permeable belts including the transfer belt, and pressed through the nonwoven web, preferably by creating a corresponding pressure differential between the roller and the outer press belt. In this case, the roller of the belt press for discharging or receiving the drying fluid is designed with an open surface. By the nonwoven web in the belt press preferably additionally acted upon by the drying fluid, the efficiency of the gentle and uniform drainage is further increased without sacrificing the volume.

In addition, it is preferred that at least one (endless) band wrapped around the drum of the belt press is permeable to water or adapted to receive water to absorb and / or accumulate the water produced by the mechanical press in the belt press to let pass.

In a further development of the inventive concept, it is proposed that the nonwoven material web is subjected to heat in the extended press nip of the belt press via the drying fluid and / or separately therefrom, for example via the roller and / or at least one belt of the belt press.

In principle, any inert gas or aerosol can be used as the drying fluid, with good results, in particular with air and / or steam.

If air is used as the drying fluid, it may, for example, have ambient temperature. Alternatively, hot air may be used as the drying fluid, preferably hot air at a temperature in a range of 50 ° C to 250 ° C, more preferably at a temperature in a range of 150 ° C to 250 ° C, and more particularly preferably at a temperature in a range of 175 ° C to 225 ° C, such as at a temperature of about 200 ° C.

When water vapor is used as the drying fluid, it is preferably used in a steam weight / weight ratio of the nonwoven web of up to 2 kg steam / kg nonwoven web and preferably in a steam weight / nonwoven web weight ratio of 0.1 to 1 kg of steam / kg nonwoven web, such as in a steam weight / weight ratio of the nonwoven web of about 0.5 kg steam / kg nonwoven web.

As stated, preferably in the belt press, simultaneously with the mechanical pressurization, a drying fluid is forced through the nonwoven web, with the roller of the belt press discharging or receiving the drying fluid having an open surface. It can be used as a roller of the belt press in particular a suction roll or a blow roll.

If the roller of the belt press is designed as a suction roll, the drying fluid is expediently, starting from a drying fluid hood at least by the permeable outer press belt, the transfer belt, the Nonwoven material web and the permeable inner band sucked or guided into the suction roll. In addition to the drying fluid, the water dehydrated in the belt press is expediently sucked or guided into the suction roll or the permeable inner band. For this purpose, the suction roll is preferably at a negative pressure (ie, a difference between atmospheric pressure and the pressure prevailing in the suction roll) in the range of 0.25 bar to 0.6 bar and particularly preferably with a negative pressure in the range of 0.30 to 0 , 55 bar, as for example, with a negative pressure of about 0.45 bar, applied.

If the roller of the belt press is designed as a suction roller, according to a preferred embodiment of the method according to the invention, the belts wrapping around the roller in the direction of flow of the drying fluid comprise a permeable press belt, preferably also the transfer belt serving for solidification and a felt belt.

If the roller of the belt press is designed as a blower roll, preferably the drying fluid is preferably blown into a hood, at least through the permeable inner band, the nonwoven material web, the transfer belt and the permeable outer press belt, starting from the blower roll. In addition to the drying fluid, the water dewatered in the belt press is expediently also blown or guided into the hood or the permeable outer band. In this embodiment of the present invention, it is preferred that the drying fluid at a pressure in the range of 0.25 bar to 0.6 bar, and more preferably at a pressure in the range of 0.30 bar to 0.55 bar, such as with a pressure in the range of about 0.45 bar, is blown above the atmospheric pressure through the permeable inner band, through the nonwoven web and through the permeable outer press belt to the hood.

When the nonwoven web in the belt press is pressurized with a drying fluid, as stated above, in addition to the pressurization, the pressure exerted on the nonwoven web also depends on, among other things, the drying fluid flow. In order to achieve a particularly good, gentle and uniform drainage, it is proposed in a further development of the inventive concept in this embodiment that a drying fluid flow in a range of 100 m ³ / (min m ² ) to 300 m ³ / (min m ² ), preferably from 150 to 250 m ³ / (min m ² ), and more preferably from about 210 m ³ / (min m ² ) is generated.

If the roller of the belt press, in addition to the inner and the outer (endless) belt and the transfer belt, is still surrounded by one or more further (endless) belts, these other (endless) belts must also be permeable to the drying fluid, provided the nonwoven fabric Material web in the belt press to be acted upon by such a drying fluid, which - as stated above - is particularly preferred.

On the one hand to achieve a sufficiently high degree of dewatering, but on the other hand perform the drainage as gently and evenly, it is provided according to a particularly preferred embodiment of the present invention that in the process at least serving as a press belt outer (endless) band with a belt tension of 20 to 100 kN / m, preferably with a belt tension of 25 to 75 kN / m and particularly preferably with a belt tension of 40 kN / m to 50 kN / m is pressed against the roll of the belt press.

In view of a sufficiently good, but at the same time the most gentle and uniform drainage, it is particularly advantageous if in the belt press on the nonwoven material web, a mechanical pressure of less than 140 kPa, in particular less than 100 kPa and preferably less than 90 kPa, but of more than 30 kPa and preferably more than 45 kPa is exercised. With such a low pressure, in particular a higher volume of the nonwoven fabric is achieved while avoiding the water congestion occurring in shoe presses, because due to the low pressure no significant compaction of the nonwoven fabric and therefore no significant volume loss occurs.

Also in view of a sufficiently good, but at the same time as gentle and uniform drainage, it is proposed in development of the invention, the residence time of the nonwoven material web in the extended press nip of the belt press on between 0.05 sec and 0.5 sec set. With such a relatively long residence time, an efficient drainage is ensured despite the relatively low pressure and the correspondingly gentle treatment of the nonwoven material web.

According to a particularly preferred embodiment of the present invention, the nonwoven material web is dewatered in the belt press by at least 20%, preferably by 30 to 75% and particularly preferably by 33 to 50%. In this case, this degree of dewatering denotes the percentage weight loss in the dewatering based on the total weight of the nonwoven material web prior to dewatering in the belt press.

If the formed nonwoven is solidified prior to transfer to the belt press, it may be advantageous in certain cases if it is preconsolidated in the region of a solidification cylinder wrapped around by the transfer belt and / or directly on the transfer belt in a region without solidification cylinder, and then preferably additionally post-solidified, wherein a respective solidification is preferably carried out by the hydroentanglement process. The device in question may thus comprise one or more solidification devices. In this case, the provided for the preconsolidation and / or provided for the Nachverfestigungseinrichtung solidifying each only one or more, preferably two nozzles for generating the solidification inducing water jets include

However, the formed nonwoven fabric can only be pre-consolidated without post consolidation, which is sufficient in certain cases.

In certain cases it may also be advantageous if no hydroentanglement takes place.

According to a preferred embodiment of the invention, a fabric tape or a dewatering tape provided with a porous surface is used as the transfer tape. It is particularly advantageous if a flat or a non-woven fabric web corresponding structuring and / or perforating tape is used as the transfer belt.

Advantageously, the nonwoven material web is considered to be mechanically dewatered in the web running direction immediately after the last solidification step and before the belt press, preferably via the structured transfer belt.

Since a lower mechanical pressure is exerted on the nonwoven material web by the belt press, a higher volume of the nonwoven fabric is achieved while avoiding the water accumulation occurring in shoe presses, since due to the low pressure no significant compaction of the nonwoven fabric and therefore no significant volume loss occurs.

In certain cases, it may be advantageous if the belt press with only two roll wrapping the (endless) belts and the transfer belt provided and the nonwoven material web between these two (endless) belts and the belts is arranged touching. In this case, both the inner (endless) belt and the transfer belt contact the nonwoven web.

In an alternative embodiment, the belt press except the inner and the outer (endless) band may also be provided with at least one further (endless) band wrapping the roller in a predetermined wrap angle. In this case, the at least one further (endless) belt can be arranged in particular between the outer press belt and the transfer belt.

Preferably, the (endless) belts wrapping the roller of the belt press comprise at least one felt belt and / or a fabric belt. In this case, it is particularly advantageous if a felt belt is used as the inner (endless) belt that wraps around the roller of the belt press. This also applies in particular if the nonwoven material web in the belt press is simultaneously passed through by a drying fluid and a suction roll is used as the roller of the belt press. Dewatering on a felt belt results in a substantially more uniform moisture cross-section than is the case, for example, with drainage by means of a suction box. In addition, with the drainage of a felt and the fiber losses are reduced.

In particular, in the case that the nonwoven material web in the belt press is preferably acted upon simultaneously by a drying fluid, all wound around the roller of the belt press (endless) belts for the drying fluid are made permeable or permeable.

In addition, it is preferred that at least one (endless) band wrapped around the drum of the belt press is permeable to water or adapted to receive water to absorb and / or accumulate the water produced by the mechanical press in the belt press to let pass.

As an outer press belt of the belt press, for example, an at least substantially smooth belt and preferably a smooth forming belt can be used.

If a structured and / or perforated nonwoven fabric is to be produced by the method according to the invention, it is provided according to a preferred embodiment of the present invention that at least one (endless) belt of the belt press contacting the nonwoven material web is provided as a structured belt through which the nonwoven material web is structured and / or perforated accordingly. The structured band may in particular be the transfer belt and / or outer press belt.

The (endless) bands of the belt press are suitably looped around the roller over the same angle of wrap.

Regardless of whether the wrap angle of the individual bands are the same or different, it is proposed in development of the invention that the wrap angle of the inner band and / or outer press belt around the roller in a range of 90 ° to 180 ° and in particular in a Range of 100 ° to 120 ° is selected. As a result, a retention time of the nonwoven material web required for sufficiently high and at the same time gentle, even dewatering is achieved in the press nip of the belt press. In principle, the residence time of the nonwoven material web in the press nip at the same roll diameter and the same roll revolution speed is the greater the greater the wrap angle of the belts.

According to a further particularly advantageous embodiment of the method according to the invention, the diameter of the roller of the belt press in a range of 500 mm to 1400 mm and preferably in a range of 750 mm chosen up to 1200 mm. Since the pressure exerted on the nonwoven web in the belt press depends, inter alia, on the wrap angle of the (endless) belts and on the diameter of the roller of the belt press, such a relatively large diameter results in a relatively long press nip and a correspondingly efficient drainage due to the longer ones Dwell time of the nonwoven material web in the press nip. In principle, the greater the diameter of the roll, the greater the residence time of the nonwoven material web in the press nip at the same wrap angle of the belts and the same roll revolution speed.

If required, the nonwoven material web can be guided through an additional dewatering press between the belt press and the thermal drying device. In such an optional additional dewatering press, a line force in a range of 20 kN / m to 100 kN / m, and more preferably a line force in a range of 50 kN / m to 90 kN / m, is preferably produced to provide a gentle and uniform, but nevertheless to achieve strong drainage.

As set forth above, it is provided according to another particularly preferred embodiment of the device according to the invention, preferably to transfer the nonwoven material web via the transfer belt in a closed train from the former to the belt press and preferably up to the thermal drying device. In this case, the transfer of the nonwoven material web from the former to the belt press or up to this downstream thermal drying device can be carried out exclusively via the one transfer belt. As already stated, the web formation also takes place in the former on this one transfer belt. The transfer belt thus also serves as a forming screen. As has also already been mentioned, solidification of the nonwoven fabric, which in particular may comprise hydroentanglement, preferably takes place on this transfer fabric. If the nonwoven material web in closed Train is at least led to the belt press, so a water jet hardening may also be omitted.

In the former upstream of the belt press, the nonwoven can also have a relatively low consistency on a smooth forming fabric or a structured forming fabric that structurally and / or perforates the nonwoven, preferably on the transfer ribbon, with a solids content of 0.01 to 0.1 Wt .-% based on 100 wt .-% of the resulting web are formed.

In this case, the nonwoven fabric can be formed in the former by any method known to those skilled in the art, preferably by a dry method, wet method and / or an extrusion method.

For example, the nonwoven may be formed in the former at least partially by a wet process, in which the fibers are in particular suspended in water and deposited on a water-permeable support.

As an alternative or in addition to this, the nonwoven in the former can also be aerodynamically formed at least partially. The fleece is formed by depositing fibers by means of an air flow on an air-permeable base.

Alternatively or in addition to this, the nonwoven in the former can also be formed at least partially mechanically. In this case, it can be formed at least partially from carding or carding removed flores, which are superposed, or formed by carding machines.

Alternatively or additionally, the nonwoven may be at least partially formed by the so-called spunbond method in which the nonwoven by depositing fibers spun from a polymer melt passing through nozzles and drawn by means of cold air and / or mechanically drawn.

As an alternative or in addition to this, the nonwoven in the former can finally be formed at least partially by the so-called melt-blow process. In this case, the nonwoven fabric is formed by depositing fibers which are directly spun from a polymer melt passing through nozzles and drawn to rupture by means of hot air streams.

In principle, the nonwoven fabric may be formed in the former not only by one of the aforementioned methods but also, in particular, by any combination of two or more of said methods.

As already mentioned, the formed nonwoven can then be solidified into a nonwoven material web, for example, by a hydroentanglement process. In this process, the formed web is consolidated by entanglement of fibers to the nonwoven web which is accomplished by tumbling, in particular by the action of focused high pressure water jets on the web. Advantageously, the fleece can be simultaneously structured and / or perforated by the application of water jet. A hydroentanglement, however, is not mandatory and may be omitted in particular when the nonwoven fibrous web is transferred in a closed train, such as by a single transfer belt, at least up to the belt press.

If the structuring and / or perforation already brought about in the former and / or in the course of hydroentanglement takes place on the transfer belt, the nonwoven material web is guided over this transfer belt at least to the belt press and through its extended press nip, which is preferred is, it is ensured that the respective structure or Peroration remains unchanged.

The material input into the former can i) at least partially from natural fibers, preferably from northern bleached kraft pulp (NBKP), hardwood pulp (LBKP), pulp from abaca fibers or cotton, ii) at least partially from artificial fibers, preferably from viscose, iii) at least partially made of synthetic fibers, preferably of polyester or polyamide, iv) at least partially made of mineral fibers, preferably glass fibers, v) at least partially made of carbon fibers and / or vi) consist of a mixture of any of the aforementioned substances.

In this case, the substance entry into the former can advantageously at least partially consist of fibers which are longer than 2 mm, preferably longer than 3 mm and particularly preferably longer than 4 mm.

The substance entry into the former may in particular also comprise wood-containing fibrous material and / or short fibers. Here are referred to as short fibers natural fibers, which have an average length of 400 to 100 mm, but always longer than 1 cm.

According to a further preferred and expedient embodiment of the invention, the nonwoven material web is produced with a weight per unit area in the range from 10 g / m ² to 1200 g / m ² .

Finally, ie after the last drying step, the nonwoven fabric can still be thermally and / or chemically solidified, if this requires the subsequent use of the nonwoven fabric.

According to a very particularly preferred embodiment of the present invention, it is provided that the (endless) bands of the belt press are designed as compared to drying fluid and preferably against air and / or water vapor permeable (endless) bands that simultaneously with the pressing of the nonwoven material web against the roll or simultaneously with the mechanical pressurization of the nonwoven web by the belt press, preferably by a pressure differential between the roller and the outer press belt, a drying fluid can be flowed through the permeable (endless) belts and the nonwoven web.

In addition, it is preferred that at least one (endless) band wrapped around the drum of the belt press is permeable to water or adapted to receive water to absorb and / or accumulate the water produced by the mechanical press in the belt press to let pass.

All the preferred embodiments described above apply equally - regardless of whether they have been explicitly described only for the method or only for the device - both for the method according to the invention and for the device according to the invention.

The invention will be described in more detail by means of an embodiment with reference to the accompanying drawings. The single figure of this drawing shows a schematic representation of an exemplary embodiment of an apparatus according to the invention for producing a nonwoven fabric.

The in the FIG. 1 purely schematically illustrated device 60 for producing a nonwoven fabric comprises a with the reference numeral 28 only indicated shaper for forming a nonwoven and a belt press 34 for further Dewatering of the nonwoven web 52 resulting from the formed web.

The web is formed in the former 28 by a web forming process or any combination of various such processes. It may be formed in particular by a dry process, a wet process and / or an extrusion process.

The formed web is, for example, by means of at least one, e.g. with two solidification devices 18, 20, which preferably operate according to the hydroentanglement method and here comprise, for example, two nozzles each. As will be understood from the following, a hydroentangling apparatus is not mandatory in every case. The consolidated nonwoven web 52 is then further dewatered.

The belt press 34 comprises a roller 36, around which at least one inner band 40 resting against the roller 36 and an outer press belt 42 are looped, resulting in an extended web direction L in the press nip 12.

The nonwoven material web 52 is guided at least together with the inner band 40, the transfer belt 10 and the outer press belt 42 between them lying through the extended press nip 12 of the belt press 34.

The press belt 42 is pressed against the roller 36 with a belt tension of at least 15 kN / m. The web is formed in the former 28 on a continuous, endless transfer belt 10, and the resulting nonwoven web 52 is passed through this transfer belt 10 at least to the belt press 34 and through its extended press nip 12, and preferably led to a reference numeral 46 only indicated thermal drying device.

As shown, the formed nonwoven together with the transfer belt 10 can, for example, pass through two solidification devices 18, 20. In this case, the first hardening device 18, viewed in the web running direction L, serves for a preconsolidation and the subsequent second hardening device 20 serves for a post-consolidation of the web. Both the pre-consolidation and the post-solidification takes place on the transfer belt 10, through which the solidified nonwoven material web 52 then at least to the belt press 34 and together with the bands 40, 42 through the extended press nip 12 and then preferably further to the thermal Drying device 46 is guided.

Downstream of the belt press 34, the nonwoven material web 52 is guided through the thermal drying device 46 together with the transfer belt 10. In this case, this thermal drying device may in particular comprise a TAD ("through air drying") or air drying device. Preferably, no more than one such TAD or air drying device is provided with preferably only one TAD cylinder.

The belts 40, 42 of the belt press 34 and the transfer belt 10 are preferably designed as drying fluid and preferably against air and / or water vapor permeable belts 40, 42, 10 so that simultaneously with the pressing of the nonwoven material web 52 against the roller 36th by a pressure difference between the roller 36 and the outer press belt 42, a drying fluid through the permeable belts 40, 42, the transfer belt 10 and the nonwoven material web 52 can flow. In this case, the roller 36 of the belt press 34 is designed for dispensing or receiving the drying fluid with an open surface

In addition, it is preferred that at least one endless belt 40, 42 looped around the drum of the belt press is permeable to water or adapted to receive water to absorb the water generated by the mechanical pressing occurring in the belt press 34 and / / or to be allowed to pass.

In particular, the belt press 34 may be configured such that the nonwoven web 52 is separated in its extended nip 12 via the drying fluid and / or separated therefrom, e.g. is applied via the roller 36 and / or one of the guided through the extended press nip 12 tapes, with heat.

In the illustrated embodiment, together with the nonwoven material web 52 - except the circulating endless inner band 40, the circulating endless outer press belt 42 and the circulating endless transfer belt 10 - another circulating endless belt 50 passed through the extended press nip 12 of the belt press 34. In this case, this further circulating belt 50 comes to rest in the press nip 12 between the transfer belt 10 and the outer press belt 42. The nonwoven fabric web 52 guided on the transfer belt 10 into and through the press nip 12 is guided by the press nip 12 between the transfer belt 10 and the inner belt 40.

Preferably, as already stated, the nonwoven material web 52 is guided together with one and the same transfer belt 10 in a closed train from the former 28, optionally through the solidification devices 18, 20, through the belt press 34 and finally to the thermal drying device 46.

The outer circumferential endless belt 42 of the belt press 34 serving as a press belt is for generating a mechanical pressure on the between the two Endless belts 40, 42 lying nonwoven fabric web with a belt tension of at least 15 kN / m stretched around the roller 36 and pressed to this roller 36. By this press belt 42, the nonwoven material web 52, the transfer belt 10 and the roller 36 touching inner endless belt 40 are pressed against the roller 36.

As already stated, it is preferred to press a drying fluid through the endless belts 40, 42, the transfer belt 10, the further belt 50 and the nonwoven material web 52, simultaneously with the mechanical pressurization of the nonwoven material web 52 by the press belt 42 of the belt press 34 by making a pressure difference between the roller 36 and the outer press belt 42. To make this possible, the endless belts 40, 42 and the transfer belt 10 and the other endless belt 50 in the present case for the drying fluid permeable, ie permeable to the drying fluid.

In particular, air or water vapor can be used as the drying fluid, it being possible to use air at ambient temperature or also hot air as the drying air.

In this case, the roller 36 of the belt press 34 can be designed in particular as a suction roll or as a blow roll. In the case of a suction roll, the drying fluid from a drying fluid hood is sucked into the suction roll at least through the permeable outer endless belt 42, the transfer belt 10, the nonwoven web and the permeable inner endless belt 40.

In the case of a blow roll, the drying fluid is blown from the blow roll at least through the permeable inner endless belt 40, the transfer belt 10, the nonwoven web and the permeable outer endless belt 42 into the hood.

Preferably, the endless belts 40, 42, 50 wrapping the roller 36 of the belt press 34 comprise at least one felt belt and / or at least one fabric belt. In this case, in particular as the roller 36 of the belt press 34 looping inner endless belt 40 may be provided a felt belt.

As an outer endless belt 42 of the belt press 34, for example, an at least substantially smooth belt, in particular smooth forming belt, can be used.

In certain cases, it is advantageous if at least one endless belt 40, 42 of the belt press 34 contacting the nonwoven material web is designed as a structured belt, by means of which the nonwoven material web is structured and / or perforated accordingly.

The endless belts 40, 42, 50 of the belt press can in particular be wound around the roller 36 over the same angle of wrap.

In the thermal drying device 46, the nonwoven material web 56 can be dried in particular to the final dry content.

In the former 28, the non-woven material having a solids content of in particular 0.01 to 0.1% can be formed on a smooth forming fabric or a structured forming fabric which structurally and / or perforates the nonwoven, preferably on the transfer tape 10.

The nonwoven can also be structured and / or perforated at the same time by the optionally provided hardening device 18, 20, which operates in particular according to the hydroentanglement method. Such a hydroentanglement device 18, 20 is therefore particularly in such Cases preferred in which the nonwoven or the nonwoven material web 52 is additionally structured and / or perforated.

The furnish in the former 28 may be i) at least partially made from natural fibers, such as northern bleached kraft pulp (NBKP), hardwood pulp (LBKP), abaca fiber pulp, cotton or the like, ii) at least partially from man-made fibers, such as Viscous or the like, iii) at least partially made of synthetic fibers, in particular of polyester, polyamide or the like, iv) at least partially of mineral fibers, in particular glass fibers or the like, v) at least partly of carbon fibers and / or vi) of a mixture of any of the aforementioned substances.

Advantageously, the substance entry into the former 28 at least partially consists of fibers which are longer than 2 mm, preferably longer than 3 mm and particularly preferably longer than 4 mm.

As already stated, hydroentanglement is not mandatory. However, it can be provided in particular in the case that the nonwoven material web 52 is additionally structured and / or perforated. Such structuring or perforation can take place, inter alia, via the solidifying devices 18, 20 operating according to the hydroentanglement method. In addition, in particular, the belt press 34 may also be provided with at least one structural band structuring and / or perforating the nonwoven material web 52, which is accordingly looped around the roller 36 again. In particular, it can perform the transfer belt 10 as the nonwoven material web 52 structuring and / or perforating structure band.

After in the present case, the nonwoven on one and the same, simultaneously serving as a forming fabric transfer belt 10 and formed by the belt press 34th through as well as to the thermal drying device 46, results in an overall extremely compact design.

As already stated, the thermal drying device 46 preferably comprises no more than one TAD or air drying device, preferably with only one TAD drying cylinder. The diameter of such a TAD drying cylinder is preferably less than 4 m, preferably less than 3.5 m and particularly preferably less than 3 m.

A respective preconsolidation may, if appropriate, take place in the region of a solidification cylinder 16 looped by the transfer belt 10 and / or directly on the transfer belt 10 in a region without consolidation cylinder, as illustrated by the solidification device 18. In the present case, the post consolidation, as shown by the solidification device 20, takes place directly on the transfer belt 10 in a region without solidification cylinder. Pre-consolidation is not always required. In certain cases, pre-consolidation without post consolidation may be sufficient.

To further increase the dewatering performance, a dewatering device for the mechanical dewatering of the nonwoven material web 52 over the structured transfer belt 10 can be provided, in particular, between the last hardening device 20 in the web running direction L and the belt press 34. Preferably, in such an additional dewatering device, a line force in a range of 20 kN / m to 100 kN / m and preferably a line force in a range of 50 kN / m to 90 kN / m can be generated.

LIST OF REFERENCE NUMBERS

10

transfer tape

12

extended press nip

16

consolidation cylinder

18

first solidification device

20

second solidification device

28

molder

34

belt press

36

roller

40

inner encircling band

42

outer circumferential press belt

46

Thermal drying device (TAD)

50

another circulating band

52

Nonwoven web

60

contraption

62

scraper

L

Web direction

Claims (13)

1. Method for manufacturing a non-woven fabric, in which method a non-woven is formed in a former (28), and the non-woven material web (52) that is created herein is subsequently further dewatered, wherein further dewatering of the non-woven material web (52) comprises dewatering by means of a belt press (34) which comprises a roller (36), at least one internal belt (40) that bears on the roller (36) and one external press belt (42) being wrapped about said roller (36), wherein the non-woven material web (52) at least in the region of the roller (36) is disposed between the internal belt (40) and the external press belt (42), wherein the press belt (42) is pressed against the roller (36) at a belt tension of at least 15 kN/m and, on account thereof, the non-woven material web (52) and the internal belt (40) are pressed against the roller (36), and wherein the non-woven in the former (28) is formed on a revolving transfer belt (10), and the non-woven material web (52) that is created herein is guided by way of this transfer belt (10) at least up to the belt press (34) and through the press nip (12) thereof, characterized in that the non-woven formed, prior to being transferred to the belt press (34), is solidified on the transfer belt (10), wherein the solidification of the non-woven formed preferably comprises a solidification according the hydro-entanglement method.
2. Method according to Claim 1, characterized in that the non-woven material web (52) downstream of the belt press (34) is guided through a thermal drying installation (46), preferably through a TAD (through-air drying) installation.
3. Method according to Claim 2, characterized in that no more than one TAD or through-air drying installation having preferably only one TAD drying cylinder is employed as the thermal drying installation (46).
4. Method according to Claim 2 or 3, characterized in that the diameter of the TAD drying cylinder is selected so as to be smaller than 4 m, preferably smaller than 3.5 m, and particularly preferably smaller than 3 m.
5. Method according to at least one of Claims 2 to 4, characterized in that the non-woven material web (52) by the transfer belt (10) is guided over the belt press (34) out to the thermal drying installation (46) and through the latter.
6. Method according to at least one of the preceding claims, characterized in that belts (40, 42, 10) that are permeable to drying fluid and preferably to air and/or water vapour are used as belts (40, 42, 10) of the belt press (34), and simultaneously with the non-woven material belt (52) being pressed against the roller (36), a drying fluid is pressed through the permeable belts (40, 42), the transfer belt (10), and the non-woven material web (52), specifically preferably by generating a respective pressure differential between the roller (36) and the external press belt (42), wherein the roller (36) of the belt press (34) for dispensing or receiving the drying fluid is embodied with an open surface.
7. Method according to at least one of the preceding claims, characterized in that a flat belt, or a belt that structures and/or perforates the non-woven material web (52) in a corresponding manner, is employed as the transfer belt (10).
8. Device (60) for manufacturing a non-woven fabric, in particular for carrying out the method according to at least one of the preceding claims, having a former (28) for forming a non-woven, and having a belt press (34) for further dewatering the non-woven material web (52) being created from the non-woven formed, wherein the belt press (34) comprises a roller (36), at least one internal belt (40) that bears on the roller (36) and one external press belt (42) being wrapped about said roller (36), the non-woven material web (52) at least in the region of the roller (36) being capable of and preferably being disposed, between the internal belt (40) and the press belt (42), the press belt (42) being capable of and preferably being pressed, against the roller (36) at a belt tension of at least 15 kN/m, and the non-woven in the former (28) being formed on a revolving transfer belt (10), and the non-woven material web (52) that is created herein being guided by way of this transfer belt (10) at least up to the belt press (34) and through the press nip (12) thereof, characterized in that the non-woven formed, prior to being transferred to the belt press (34), together with the transfer belt (10) passes through at least one solidification installation (18, 20) in which said non-woven formed is solidified on the transfer belt (10), wherein the at least one solidification installation (18, 20) preferably comprises a hydro-entanglement installation.
9. Device according to Claim 8, characterized in that the non-woven material web (52) downstream of the belt press (34) is guided through a thermal drying installation (46), preferably through a TAD (through-air drying) installation.
10. Device according to Claim 8, characterized in that the thermal drying installation (46) comprises not more than one TAD or through-air drying installation having preferably only one TAD drying cylinder.
11. Device according to Claim 9 or 10, characterized in that the diameter of the TAD drying cylinder is smaller than 4 m, preferably smaller than 3.5 m, and particularly preferably smaller than 3 m.
12. Device according to at least one of Claims 9 to 11, characterized in that the non-woven material web (52) by the transfer belt (10) is guided over the belt press (34) out to the thermal drying installation (46) and through the latter.
13. Device according to at least one of Claims 8 to 10, characterized in that the belts (40, 42, 10) of the belt press (34) are configured as belts (10, 40, 42) that are permeable to drying fluid and preferably to air and/or water vapour such that, simultaneously with the non-woven material belt (52) being pressed against the roller (36), by a pressure differential between the roller (36) and the external press belt (42), a drying fluid can be allowed to flow through the permeable belts (40, 42), the transfer belt (10), and the non-woven material web (52), wherein the roller (36) of the belt press (34) for dispensing or receiving the drying fluid is embodied with an open surface.

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