EP3017104B1 - Method for retrofitting and operating a device for producing a non-woven fabric - Google Patents

Description

The present invention relates to a method for converting a device comprising suction pipes and / or suction boxes for producing a nonwoven fabric in order to increase the production capacity and energy efficiency of the device and to operate the device.

A nonwoven fabric is a structure of fibers of limited length, of continuous fibers (filaments) or of cut yarns of any kind and of any origin, which are somehow combined to form a nonwoven (ie a fiber layer or a fiber web) and bonded to one another in some way have been. Nonwoven fabrics do not include fiber structures produced by crossing or intertwining yarns, as is the case with weaving, knitting, knitting, lace manufacture, braiding and the manufacture of tufted products. Films and papers are also not among the nonwovens.

Processes for producing nonwovens have become known, inter alia, from: EP1518960 A1 . WO2012 / 143163 A1 . WO2008 / 077874 A1 . WO2013 / 009256 A1 . FR2733522 A1 such as WO2010 / 030298 ,

Known processes for the production of nonwovens generally include nonwoven formation, nonwoven consolidation and subsequent dewatering. Different methods of web formation are for example in the WO 2007/018960 A2 described. The fleece can in particular be formed by a dry process, a wet process and / or an extrusion process the. In principle, any combination of such fleece formation processes is also conceivable.

The subsequent nonwoven bonding can take place, for example, mechanically or according to the so-called water jet bonding process - which is also called "spunlacing". In principle, however, other solidification methods are also conceivable. In the water jet consolidation process, the nonwoven formed is solidified by entangling the fibers, the entangling being effected by swirling, in particular focused high-pressure water jets acting on the nonwoven.

In particular after such a consolidation according to the water jet consolidation method, the nonwoven material web formed has a relatively high level of moisture, which subsequently has to be removed again from the material web.

In order to reduce the costs for the subsequent drying process and in particular a subsequent thermal drying, suction tubes or suction boxes which have been subjected to vacuum have been used so far after the water jet consolidation. With such suction pipes or suction boxes, the aim was to increase the dryness of the nonwoven material web as much as possible without losing volume.

However, such drainage by means of suction pipes or suction boxes has a number of disadvantages. So the drainage performance of suction boxes is limited. However, they are used because they have practically no influence on the product quality parameters, whereas mechanical pressing, which is used alternatively for dewatering, would have a negative effect on many products. Due to the limited drainage capacity of suction pipes or suction boxes, the subsequent dryer section can become a bottleneck in terms of production capacity. Conventional suction pipes or suction boxes comprising devices for producing nonwovens have a production capacity of only 700 to 900 kg / m / h. on. To be competitive these systems have to be converted. This problem is currently being countered by increasing the drying capacity. However, increasing the drying capacity in existing plants is not easy, because in most of these plants it is necessary to install one or more additional TAD ("through air drying") drying cylinders. However, this is disadvantageous because such drying cylinders are very large, but the available space in existing nonwoven production plants is limited.

Another disadvantage of suction pipes or suction boxes is that they destroy or at least impair the desired uniform cross-sectional moisture profile of the nonwoven material web, which is due in particular to air losses at the edges of the material web due to a non-constant width of the material web and to the technology of some suction pipes or boxes is due. An uneven moisture cross profile can place limitations on the manufacturing process, particularly with regard to thermal consolidation. The loss of air at the edges of the material web also entails high energy consumption. Depending on the weight per unit area, nonwoven material composition and structure of the nonwoven material web, which can also be structured or perforated, for example, the dry content of the nonwoven material web obtained after dewatering is limited. As a result of the relatively high vacuum, the transfer belt in question, with which the nonwoven material web is guided over the suction pipes or boxes, and which is usually a fabric belt, a forming screen or a structuring belt that structures and / or perforates the nonwoven, there is a loss of fibers due to so-called "fiber plucking". The plucked fibers pollute the wastewater and are lost to the manufacturing process. In addition, these fibers bring with them additional contamination of the water reprocessed for water jet consolidation, so that additional filtration steps and a more complex reprocessing system, in which, for example, fresh fiber material has to be added, are required. Fiber losses occur mainly as a result of air losses at the edges of the nonwoven material web, tearing and / or breaking of the fibers and sucking the fibers into the suction boxes. With certain products, such as those for which material mixtures are used, the relatively large suction forces in particular lead to fiber loss.

Fibers sucked into the drainage system tend to contaminate the water used for hydroentangling and make reprocessing and filtration more difficult, particularly when using fiber pulp.

From the DE 10 2006 042 507 A1 For example, it is known to use a shoe press to drain a nonwoven material web. Such a shoe press, viewed in the direction of web travel, has an extended press nip or press nip - in comparison to a roll nip. As a result of the relatively high pressing pressure of the shoe press, there is a disturbing water build-up in front of the press nip of the shoe press. In addition, the relatively high pressure of the shoe press leads to a reduction in the volume of the nonwoven.

The invention is therefore based on the object of a method for retrofitting an existing device for producing a nonwoven fabric, with which an improved and, in particular, more efficient device for producing a nonwoven fabric is obtained from an existing device comprising suction pipes and / or suction boxes, which device achieves the above does not have the disadvantages mentioned and in particular - while avoiding a water build-up - leads to efficient and inexpensive dewatering of the nonwoven material web formed and to a nonwoven material web with the largest possible volume and with a uniform moisture cross profile. In particular, this should already be done before The drying section of the nonwoven material web should be as dry as possible in order to be able to limit the number of large and bulky drying cylinders and thus make optimal use of the space available for the device. Furthermore, the overall energy consumption should be reduced. In addition, the fiber losses should be kept as low as possible, the overall dewatering efficiency and drying efficiency should be increased and the production capacity of the device should be increased.

According to the invention, this object is achieved by a method for converting a former to form a fleece, suction pipes and / or suction boxes for dewatering the fleece according to claim 1.

• Entfernen aller stromaufwärts der Trocknungseinrichtung angeordneten Saugrohre und/oder Saugkästen und
• Installieren einer Bandpresse zwischen dem Former und der Trocknungseinrichtung, wobei die Bandpresse eine Walze umfasst, um die zumindest ein an die Walze anliegendes inneres Band und ein äußeres Pressband geschlungen sind, wobei eine aus dem in dem Former gebildeten Vlies entstehende Vliesstoff-Materialbahn zumindest im Bereich der Walze zwischen dem inneren Band und dem äußeren Pressband anordenbar und bevorzugt angeordnet ist, und, wobei das Pressband mit einer Bandspannung von zumindest 15 kN/m an die Walze pressbar und bevorzugt gepresst ist.

According to the invention, a method for retrofitting a former for forming a nonwoven, suction pipes and / or suction boxes for dewatering the nonwoven and a device for producing a nonwoven comprising a drying device comprises the following steps:

• Removal of all suction pipes and / or suction boxes and arranged upstream of the drying device
• Installation of a belt press between the former and the drying device, the belt press comprising a roller, around which at least one inner belt adjoining the roller and an outer press belt are wound, a nonwoven material web formed from the nonwoven formed in the former at least in the region the roller can be arranged and preferably arranged between the inner belt and the outer press belt, and, the press belt being pressable and preferably pressed onto the roll with a belt tension of at least 15 kN / m.

It goes without saying that when the method is carried out, the nonwoven material web and the belts run around the roller, which is why both the inner belt and the outer press belt are preferably designed as endless belts.

For the purposes of the present invention, nonwoven is understood to mean an unconsolidated nonwoven fabric of low consistency obtained directly by molding, whereas nonwoven is understood to mean a nonwoven fabric that is already higher in consistency than immediately after shaping and preferably consolidated.

For the purposes of the present invention, in accordance with the present invention, belt tension of the outer press belt is understood to mean the quotient of the tensile stress applied to the press belt and the width of the press belt.

By removing, according to the invention, all the suction pipes and / or suction boxes arranged upstream of the drying device and replacing them with a belt press arranged between the former and the drying device and designed as described above, the disadvantages associated with suction pipes and suction boxes, such as, in particular, limited drainage capacity, limited production capacity, large space requirement, production of nonwovens with uneven moisture cross profile, fiber loss in the production by "fiber plucking" and the like are overcome and a device is obtained with which a nonwoven fabric can be efficiently and inexpensively, with gentle, uniform and efficient dewatering of the nonwoven material web formed and below Formation of a nonwoven material web with a very large volume and with an even moisture cross profile is available. In this way, the device thus converted achieves a very high dry content of the nonwoven material web, especially before the dryer section, so that the number of large and bulky drying cylinders is limited to a maximum can be limited and so the space available for the device can be optimally used. For this reason, the space in the device which is freed up by the removal of the suction pipes and suction boxes is sufficient to integrate the new device parts, namely belt press, into the device without additional space being required. In addition, the replacement of the suction pipes and suction boxes by the belt press is more effective in terms of drainage performance than the replacement of the suction pipes and suction boxes by one or more additional drying cylinders, such as TAD cylinders or the like. Overall, the device converted in this way has a significantly reduced energy consumption. In addition, there is hardly any fiber loss during their operation.

In order to enable a particularly gentle and uniform dewatering of the nonwoven material web in the belt press, it is proposed in a further development of the inventive concept that the roller of the belt press for dispensing or receiving drying fluid is designed with an open surface and the belts of the belt press as compared to drying fluid and preferably tapes permeable to air and / or water vapor are formed such that a drying fluid is allowed to flow through the permeable tapes and the nonwoven material web simultaneously with the pressing of the nonwoven material web against the roller by a pressure difference between the roller and the outer press belt can.

In addition, it is preferred that at least one (endless) belt wound around the roller of the belt press is permeable to water or is designed in such a way that it can absorb water in order to absorb the water occurring during the mechanical pressing taking place in the belt press and / or to let through.

According to a particularly preferred variant of this embodiment, the roller of the belt press is designed as a suction roller so that the drying fluid starting from preferably a drying fluid hood, it can be sucked into the suction roll at least through the permeable outer press belt, the nonwoven material web and the permeable inner belt. In addition to the drying fluid, the water dewatered in the belt press is also expediently sucked or guided into the suction roll or the permeable inner belt.

According to another particularly preferred variant of this embodiment, the roller of the belt press is designed as a blowing roller such that the drying fluid, starting from the blowing roller, can preferably be blown into a hood at least through the permeable inner belt, the nonwoven material web and the permeable outer pressing belt. In addition to the drying fluid, the water dewatered in the belt press is also expediently blown or guided into the hood or the permeable outer belt.

A device for strengthening the nonwoven formed to a nonwoven material web is preferably arranged between the former and the belt press, in order to solidify the nonwoven formed in the former before further dewatering in the belt press.

The consolidation device can be a mechanical consolidation device and particularly preferably a water jet consolidation device.

The dewatering performance of the belt press depends in particular on the roll diameter, the roll rotation speed and the wrap angle, ie the angle at which the nonwoven material web wraps around the roll. Good results are obtained in this regard in particular if the diameter of the roller of the belt press is in a range from 500 mm to 1400 mm and preferably in a range from 750 mm to 1200 mm.

In a further development of the inventive concept, it is proposed that the nonwoven material web is or is transferred in a closed train from the former to the belt press and preferably to the drying device.

This can be achieved particularly simply by transferring the nonwoven material web from the former to the belt press and preferably to the drying device via a single transfer belt, such as a forming fabric.

In order to be able to dry the nonwoven material web further dewatered in the belt press to the final dry content, at least one thermal drying device is preferably provided downstream of the belt press. Good results are obtained in particular if the thermal drying device is a TAD ("through air drying") or air drying unit or a flat bed oven

In order to achieve a space-saving nonwoven fabric manufacturing device, it is provided according to a further particularly preferred embodiment that the thermal drying device does not comprise more than one drying cylinder and / or TAD through-flow cylinder.

If a further dewatering in addition to that achieved by the belt press and the drying device is necessary or expedient, an additional dewatering press can be provided between the belt press and the thermal drying device, for example. In this embodiment, a line force in a range from 20 kN / m to 100 kN / m and preferably a line force in a range from 50 kN / m to 90 kN / m can preferably be generated in the dewatering press.

• Bilden eines Vlieses in dem Former,
• weiteres Entwässern der aus dem Vlies entstehenden Vliesstoff-Materialbahn, wobei die weitere Entwässerung der Vliesstoff-Materialbahn die Entwässerung in der Bandpresse umfasst, wobei die Vliesstoff-Materialbahn zumindest im Bereich der Walze zwischen dem inneren Band und dem äußeren Pressband angeordnet wird und das Pressband mit einer Bandspannung von zumindest 15 kN/m an die Walze gepresst und dadurch die Vliesstoff-Materialbahn und das innere Band gegen die Walze gepresst werden, sowie
• Führen der Vliesstoff-Materialbahn durch die Trocknungseinrichtung, um die Vliesstoff-Materialbahn auf den Endtrockengehalt zu bringen.

Another object, which is not however covered by the claims, is a method for operating a device converted according to the method described above for producing a nonwoven fabric, which comprises the following steps:

• Forming a fleece in the former,
• further dewatering of the nonwoven material web arising from the nonwoven, the further dewatering of the nonwoven material web comprising dewatering in the belt press, the nonwoven material web being arranged at least in the region of the roller between the inner band and the outer press band and the press band with a belt tension of at least 15 kN / m pressed against the roller, thereby pressing the nonwoven material web and the inner belt against the roller, and
• Guide the nonwoven material web through the drying device in order to bring the nonwoven material web to the final dry content.

This configuration of the method results in an overall more efficient, less expensive drainage of the nonwoven material web formed. In addition to the advantages for the manufacture of nonwoven fabric already described above in comparison with a suction pipe and suction boxes, the method according to the invention avoids the water jam before the press nip, which has hitherto occurred especially in connection with a shoe press, in comparison to the use of a shoe press Larger volume of the nonwoven material web produced is achieved because the pressure in the extended press nip of the belt press is lower than that of a shoe press. As a result of the longer dwell time of the nonwoven material web in the nip compared to the use of a shoe press, efficient dewatering with a high degree of dewatering is ensured despite the lower pressing pressure. Because of this, a thermal drying device, such as, for example, is required after the belt press TAD (Through Air Drying) - or air drying unit, only a very small amount of energy. In addition, in the method according to the invention, due to the belt press used, a very gentle and - based on the surface of the nonwoven material web - very uniform dewatering is achieved in comparison with the methods known from the prior art, so that impairment or even destruction of the fiber structure is reliable is prevented. Because of this, fiber losses and contamination of the wastewater are also kept to a minimum. In addition, the process according to the invention also provides an improved moisture cross profile for the nonwoven fabric formed.

The method according to 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, as a result of which the ability to machine in the dryer section is increased. As a result of the reduced pressure in the belt press, the volume of the nonwoven material web during dewatering is not reduced by more than 10%. As a result, the solids content of the nonwoven material web relative to the water content can be increased by more than 10% compared to the drainage by suction boxes that has been customary up to now, which results in a higher production capacity, energy consumption is reduced and the provision of additional or more complex drying devices is avoided.

According to a very particularly preferred embodiment, the roller of the belt press is designed for dispensing or receiving drying fluid with an open surface and is used as belts of the belt press with drying fluid and preferably with air and / or water vapor permeable belts and is used simultaneously with the pressing of the nonwoven material. Material web pressed against the roller, a drying fluid through the permeable belts and the nonwoven material web, preferably by generating a corresponding pressure difference between the roller and the outer press belt. Since the nonwoven material web in the belt press is preferably additionally acted upon by the drying fluid, the efficiency of the gentle and uniform dewatering is further increased without loss of volume.

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

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

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

As stated, a drying fluid is preferably pressed through the nonwoven material web in the belt press at the same time as the mechanical pressure is applied, the roller of the belt press being used to discharge or take up the Drying fluids is designed with an open surface. A suction roller or a blowing roller can be used as the roller. If the roller of the belt press is designed as a suction roller, the drying fluid is expediently sucked or guided into the suction roller starting from a drying fluid hood, at least through the permeable outer press belt, the nonwoven material web and the permeable inner belt. For this purpose, the suction roll is preferably with a negative pressure (ie a difference between atmospheric pressure and the pressure prevailing in the suction roll) in the range from 0.25 bar to 0.6 bar and particularly preferably with a negative pressure in the range from 0.30 bar to 0.55 bar, such as a vacuum of about 0.45 bar.

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

If, in addition to the pressurization, a drying fluid is applied to the nonwoven material web in the belt press, which pressure is preferred, the pressure exerted on the nonwoven material web also depends, among other things, on the drying fluid flow. In order to achieve particularly good, gentle and uniform drainage, it is proposed in this embodiment that that through the belts a drying fluid flow in a range from 100 m ³ / (min m ² ) to 300 m ³ / (min m ² ), preferably from 150 to 250 m ³ / (min m ² ) and particularly preferably from about 210 m ³ / (min m ² ) is generated.

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

In order to achieve a sufficiently high degree of dewatering on the one hand, but on the other hand to carry out the dewatering as gently and evenly as possible, it is provided according to a particularly preferred embodiment of the present invention that in the method at least the outer (endless) belt serving as a press belt with a belt tension of 20 up 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 onto the roller of the belt press.

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

Also with regard to a sufficiently good, but at the same time as gentle and uniform drainage, it is proposed to set the dwell time of the nonwoven material web in the extended press nip of the belt press to between 0.05 seconds and 0.5 seconds. With such a relatively long residence time, efficient dewatering is ensured despite the relatively low pressure and the correspondingly gentle treatment of the nonwoven material web.

According to a particularly preferred embodiment, 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%. This degree of dewatering denotes the percentage weight loss during dewatering based on the total weight of the nonwoven material web before dewatering in the belt press.

In certain cases it can be advantageous if the belt press is provided with only two (endless) belts wrapping around the roller and the nonwoven material web between these two (endless) belts and the belts are arranged in contact. In this case, both the inner (endless) belt and the outer press belt touch the nonwoven material web.

In an alternative embodiment to this, in addition to the inner and the outer (endless) belt, the belt press can also be provided with at least one further (endless) belt that wraps around the roller at a predetermined wrap angle. The at least one further (endless) belt can in particular be arranged between the outer press belt and the nonwoven material web.

Preferably, the (endless) belts wrapping around the roller of the belt press comprise at least one felt belt and / or a fabric belt. It is special of advantage 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 when a drying fluid flows through the nonwoven material web in the belt press and a suction roller is used as the roller of the belt press. If a blowing roller is used as the roller, then at least one outer (endless) belt lying behind the nonwoven material web, viewed in the flow direction of the drying fluid, can be provided as a felt belt. Dewatering on a felt belt results in a much more uniform moisture cross profile than is the case, for example, with dewatering by means of a suction box. In addition, dewatering on a felt also reduces fiber losses.

In particular, in the event that the nonwoven material web in the belt press is preferably acted upon simultaneously by a drying fluid, all (endless) belts wrapped around the roller of the belt press are designed to be permeable or permeable to the drying fluid.

In addition, it is preferred that at least one (endless) belt wound around the roller of the belt press is permeable to water or is designed in such a way that it can absorb water in order to absorb the water occurring during the mechanical pressing taking place in the belt press and / or to let through.

For example, an at least essentially smooth belt and preferably a smooth forming belt can be used as the outer (endless) belt of the belt press.

If a structured and / or perforated nonwoven is to be produced using the method according to the invention, it is provided according to a preferred embodiment of the present invention that at least one of the nonwoven material webs Touching (endless) belt of the belt press is provided as a structured belt, through which the nonwoven material web is structured and / or perforated accordingly.

If the nonwoven material web in the belt press is preferably also pressurized with a drying fluid at the same time as the pressurization and more than two permeable (endless) belts are wrapped around the roller of the belt press, these (endless) belts can be viewed in particular in the flow direction of the drying fluid include, for example, a permeable (endless) belt, an endless smooth forming fabric, an endless permeable fabric belt, and an endless permeable felt belt. In principle, however, it is also possible to provide fewer or more (endless) tapes and / or a different sequence of these (endless) tapes.

1. a) ein um die Walze gespanntes permeables Pressband, ein permeables Gewebeband und ein permeables Filzband, oder
2. b) ein um die Walze gespanntes permeables Pressband, ein permeables Siebband, ein permeables Gewebeband und ein permeables Filzband, oder
3. c) ein um die Walze gespanntes permeables Pressband, ein permeables Filzband, ein permeables Gewebeband und ein permeables Filzband, oder
4. d) ein um die Walze gespanntes permeables Filzpressband, ein permeables Gewebeband und ein permeables Filzband.

According to a preferred embodiment, the roller of the belt press is designed as a suction roller and comprises the belts wrapping around the roller, viewed in the flow direction of the drying fluid

1. a) a permeable press belt stretched around the roller, a permeable fabric belt and a permeable felt belt, or
2. b) a permeable press belt stretched around the roller, a permeable screen belt, a permeable fabric belt and a permeable felt belt, or
3. c) a permeable press belt stretched around the roller, a permeable felt belt, a permeable fabric belt and a permeable felt belt, or
4. d) a permeable felt press belt stretched around the roller, a permeable fabric belt and a permeable felt belt.

1. a) ein um die Walze gespanntes permeables Pressband, ein permeables Gewebeband und ein permeables Filzband, oder
2. b) ein um die Walze gespanntes permeables Pressband, ein permeables Siebband, ein permeables Gewebeband und ein permeables Filzband, oder
3. c) ein um die Walze gespanntes permeables Pressband, ein permeables Filzband, ein permeables Gewebeband und ein permeables Filzband, oder
4. d) ein um die Walze gespanntes permeables Filzpressband, ein permeables Gewebeband und ein permeables Filzband.

According to another preferred embodiment, the roller of the belt press is designed as a blowing roller and includes the belts wrapping around the roller, viewed in the flow direction of the drying fluid

1. a) a permeable press belt stretched around the roller, a permeable fabric belt and a permeable felt belt, or
2. b) a permeable press belt stretched around the roller, a permeable screen belt, a permeable fabric belt and a permeable felt belt, or
3. c) a permeable press belt stretched around the roller, a permeable felt belt, a permeable fabric belt and a permeable felt belt, or
4. d) a permeable felt press belt stretched around the roller, a permeable fabric belt and a permeable felt belt.

The (endless) belts of the belt press are advantageously wrapped around the roller over the same wrap angle.

Regardless of whether the wrap angles of the individual belts are the same or different from one another, it is proposed in a further development of the inventive concept that the wrap angle of the inner belt and / or outer press belt around the roller in a range from 90 ° to 180 ° and in particular in one Range from 100 ° to 120 ° is selected. This achieves a dwell time of the nonwoven material web in the press nip of the belt press which is necessary for a sufficiently high and at the same time gentle, uniform dewatering. Basically, the dwell time of the nonwoven material web in the press nip is the greater with the same roll diameter and the same roll rotation speed, 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 is selected in a range from 500 mm to 1400 mm and preferably in a range from 750 mm to 1200 mm. Since the pressure exerted on the nonwoven material web in the belt press depends, among other things, on the wrap angle of the (endless) belts and on the diameter of the roller of the belt press such a relatively large diameter, a relatively long press nip and a correspondingly efficient drainage due to the longer dwell time of the nonwoven material web in the press nip. Basically, the dwell time of the nonwoven material web in the press nip with the same wrap angle of the belts and the same roll rotation speed is greater, the larger the roll diameter.

Downstream or downstream of the belt press, the nonwoven material web can in particular be guided through at least one TAD ("through air drying") or air drying unit or a flat bed oven as a thermal drying device. The nonwoven material web can be brought to the final dry content in particular by such a thermal drying device. If necessary, the nonwoven material web can be passed between the belt press and such a thermal drying device through an additional dewatering press. In such an optional additional dewatering press, a line force in a range from 20 kN / m to 100 kN / m and particularly preferably a line force in a range from 50 kN / m to 90 kN / m is generated in order to be gentle and uniform, but nevertheless achieve strong drainage.

According to a further preferred embodiment of the device, the nonwoven material web is guided in a closed train from the former at least to the belt press and preferably to a thermal drying device arranged downstream of it. In this case, the transfer of the nonwoven material web from the former to the belt press or to the thermal drying device downstream of it can take place via a single transfer belt. According to a further preferred embodiment of the device, the transfer belt is formed by the forming wire, on which in the former the fleece is formed. In particular, in the event that the nonwoven material web is guided in a closed train at least to the belt press, water jet consolidation can be omitted.

In the former upstream of the belt press, the nonwoven can in particular also have a relatively low consistency on a smooth forming fabric or a structured forming fabric which structures and / or perforates the nonwoven accordingly and has a solids content of 0.01 to 0.1% by weight based on 100% by weight of the nonwoven obtained are formed.

The fleece can be formed in the former by any method known to the person skilled in the art, preferably by a dry method, wet method and / or an extrusion method.

For example, the fleece can be formed in the former at least in part by a wet process, in which the fibers are suspended, in particular, in water and placed on a water-permeable surface.

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

As an alternative or in addition to this, the nonwoven can also be formed at least partially mechanically in the former. It can be formed at least in part from sheets taken from cards or cards, which are placed one on top of the other, or from carding machines.

As an alternative to this or in addition to this, the nonwoven can also be formed at least partially by the so-called spunbond process, in which the nonwoven by depositing fibers which are spun from a polymer melt passing through nozzles and stretched by means of cold air and / or mechanically.

As an alternative to this or in addition to this, the nonwoven in the former can finally also be formed at least in part by the so-called melt-blow process. The fleece is formed by laying down fibers that are spun directly from a polymer melt passing through nozzles and stretched until they tear by means of hot air currents.

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

Then, i.e. after its formation in the former and before further dewatering, the nonwoven formed can be consolidated by a consolidation process, which preferably comprises mechanical consolidation and / or water jet consolidation. In the case of water jet consolidation, the nonwoven formed is solidified by entangling fibers to form the nonwoven material web, which is effected by swirling, in particular by focused high-pressure water jets acting on the nonwoven. Advantageously, the nonwoven can also be structured and / or perforated at the same time by the water jet. However, water jet consolidation is not mandatory and can in particular be dispensed with if the nonwoven-fibrous web is transferred at least to the belt press in a closed train, for example by means of a single transfer belt.

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 artificial fibers, preferably made of viscose, iii) at least partially from synthetic fibers, preferably from polyester or polyamide, iv) at least partially from mineral fibers, preferably glass fibers, v) at least partially from carbon fibers and / or vi) from a mixture of any of the above mentioned substances exist.

The material input into the former can advantageously at least partially consist of fibers that are longer than 2 mm, preferably longer than 3 mm and particularly preferably longer than 4 mm.

According to a further preferred and expedient embodiment of the method according to the invention, in particular for producing a nonwoven material web with a basis weight of greater than 50 g / m ² , preferably greater than 80 g / m ² and particularly preferably greater than 100 g / m ² the nonwoven material web before or after the belt press is additionally guided over a vacuum roller with a vacuum.

In conclusion, i.e. After the last drying step, the nonwoven can be thermally and / or chemically consolidated if this requires the later use of the nonwoven.

Fig. 1

eine schematische Darstellung einer herkömmlichen Vorrichtung zur Herstellung von Vliesstoffen,

Fig. 2

eine schematische Darstellung einer ersten beispielhaften Ausführungsform einer erfindungsgemäß umgerüsteten Vorrichtung und

Fig. 3

eine schematische Darstellung einer weiteren beispielhaften Ausführungsform der Bandpresse der erfindungsgemäß umgerüsteten Vorrichtung mit einer oberhalb der Walze der Bandpresse angeordneten Haube zur Abgabe oder Aufnahme von Trocknungsfluid.

The invention is described in more detail below using exemplary embodiments with reference to the accompanying drawing; in this show:

Fig. 1

1 shows a schematic representation of a conventional device for producing nonwovens,

Fig. 2

a schematic representation of a first exemplary embodiment of a device converted according to the invention and

Fig. 3

is a schematic representation of another exemplary embodiment of the belt press of the device converted according to the invention with a hood arranged above the roller of the belt press for dispensing or taking up drying fluid.

The Fig. 1 shows a schematic representation of a conventional device 10 for producing nonwovens with a former 12, a water jet consolidation device 14, a drainage device 18 comprising a plurality of suction pipes or suction boxes 16 and two thermal drying devices 20, namely two TAD or air drying units, an immersion bath 22 for loading the dried ones Nonwoven material web with a finishing agent and a winding device 24.

In the former 12 comprising a forming wire 26, the fleece is formed with a low consistency by the wet process.

In this known device 10, the above-mentioned problems arise in particular due to the drainage device 18 comprising suction pipes or boxes 16.

• Entfernen aller stromaufwärts der Trocknungseinrichtung 20 angeordneten Saugrohre und/oder Saugkästen 16 und
• Installieren einer Bandpresse zwischen dem Former 12 und der Trocknungseinrichtung 20, wobei die Bandpresse eine Walze umfasst, um die zumindest ein an die Walze anliegendes inneres Band und ein äußeres Pressband geschlungen sind, wobei eine aus dem in dem Former gebildeten Vlies entstehende Vliesstoff-Materialbahn zumindest im Bereich der Walze zwischen dem inneren Band und dem äußeren Pressband anordenbar und bevorzugt angeordnet ist, und, wobei das Pressband mit einer Bandspannung von zumindest 15 kN/m an die Walze pressbar und bevorzugt gepresst ist.

In order to overcome these problems or disadvantages, a device for producing a nonwoven fabric, as configured above according to the prior art, is converted, namely by the following steps:

• Removal of all suction pipes and / or suction boxes 16 and 16 arranged upstream of the drying device 20
• Installing a belt press between the former 12 and the drying device 20, the belt press comprising a roller, around which at least one inner belt abutting the roller and an outer belt Press belt are looped, whereby a nonwoven material web arising from the nonwoven formed in the former can be arranged and preferably arranged at least in the area of the roller between the inner belt and the outer press belt, and, the press belt having a belt tension of at least 15 kN / m is pressable to the roller and preferably pressed.

From the Fig. 2 The basic principle of the nonwoven fabric production carried out with the device converted according to the invention initially results in an exemplary representation.

The nonwoven is then formed in a former 28 of a device 30 for manufacturing nonwovens according to a specific method or any combination of such methods. The nonwoven formed is, for example, mechanically consolidated by means of a water jet consolidation device 32 and / or the like, and the consolidated nonwoven material web is then further dewatered. As can be seen from the following, consolidation is not mandatory in every case.

The further dewatering of the nonwoven material web formed from the nonwoven formed comprises dewatering by means of a belt press 34 with a roller 36, around which at least one inner endless belt 40 contacting the roller and an outer serving as a pressing belt form a prolonged press nip 38 over a respective wrap angle Endless belt 42 is looped.

The fleece can be formed in the former 28 in particular by a dry process, a wet process and / or an extrusion process.

The outer endless belt 42 of the belt press 34, which serves as a press belt, is tensioned around the roller 36 or pressed against this roller 36 in order to generate a mechanical pressure on the nonwoven material web lying between the two endless belts 40, 42 with a belt tension of at least 15 kN / m . This press belt 42 presses the nonwoven material web and the inner endless belt 40 touching the roller 36 against the roller 36.

A drying fluid is preferably pressed through the endless belts 40, 42 and the nonwoven material web simultaneously with the mechanical pressurization of the nonwoven material web by the press belt 42 of the belt press 34, namely by generating a pressure difference between the roller 36 and the outer press belt 42 to enable this, the endless belts 40, 42 are permeable to the drying fluid in the present case, ie permeable to the drying fluid. In addition, the roller 36 of the belt press 34 in this embodiment is designed to deliver or receive the drying fluid with an open surface. It can be formed in particular by a suction or blowing roller.

In addition, it is preferred that at least one (endless) belt 40, 42 wrapped around the roller of the belt press is permeable to water or is designed in such a way that it can absorb water, around the water occurring during the mechanical pressing taking place in the belt press 34 to be able to record and / or let through.

Air or water vapor can be used in particular as the drying fluid, and air at ambient temperature or hot air can be used as the drying air.

In the case of a suction roll, the drying fluid is emitted from a drying fluid hood 44 at least through the permeable outer endless belt 42 Nonwoven material web and the permeable inner endless belt 40 are sucked or guided into the suction roll.

In the case of a blow roller, the drying fluid is blown or guided into the hood 44 from the blow roller at least through the permeable inner endless belt 40, the nonwoven material web and the permeable outer endless belt 42.

The belt press 34 can, as shown, be provided, for example, with only two endless belts 40, 42 wrapping around the roller 36. The nonwoven material web lying between these endless belts 40, 42 is in this case touched by the two endless belts 40, 42.

In principle, however, in addition to the inner and outer endless belts 40, 42, the belt press 34 can also be provided with at least one further endless belt that wraps around the roller 36 over a specific wrap angle. At least one such further endless belt can be arranged, for example, between the outer endless belt 42 and the nonwoven material web.

The endless belts 40, 42 wrapping around the roller 36 of the belt press 34 preferably comprise at least one felt belt and / or at least one fabric belt. In particular, a felt belt can be provided as the inner endless belt 40 that wraps around the roller 36 of the belt press 34. If the nonwoven material web in the belt press 34 is preferably additionally acted upon by a drying fluid, at least one felt band is provided behind the nonwoven material web at least in the flow direction of the drying fluid.

In particular, in the event that a drying fluid is additionally applied to the nonwoven material web in the belt press 34, which is preferred, as already mentioned, all are wound around the roller 36 of the belt press 34 Endless belts 40, 42 are designed to be permeable or permeable to the drying fluid.

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

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, through which the nonwoven material web is structured and / or perforated accordingly.

According to an expedient embodiment, the endless belts 40, 42 wrapping around the roller 36 of the belt press 34 comprise, in particular in the flow direction of the drying fluid, a permeable endless belt, an endless smooth forming fabric, an endless fabric belt and an endless felt belt. In principle, however, fewer or more endless belts and / or the endless belts can also be provided in a different order than that just mentioned.

1. a) ein um die Walze 36 gespanntes permeables Pressband, ein permeables Gewebeband und ein permeables Filzband, oder
2. b) ein um die Walze 36 gespanntes permeables Pressband, ein permeables Siebband, ein permeables Gewebeband und ein permeables Filzband, oder
3. c) ein um die Walze 36 gespanntes permeables Pressband, ein permeables Filzband, ein permeables Gewebeband und ein permeables Filzband, oder
4. d) ein um die Walze 36 gespanntes permeables Filzpressband, ein permeables Gewebeband und ein permeables Filzband.

If the roller 36 of the belt press 34 is designed as a suction roller, then the belts wrapping around the roller 36 preferably comprise viewed in the flow direction of the drying fluid

1. a) a permeable press belt stretched around the roller 36, a permeable fabric belt and a permeable felt belt, or
2. b) a permeable press belt stretched around the roller 36, a permeable screen belt, a permeable fabric belt and a permeable felt belt, or
3. c) a permeable press belt stretched around the roller 36, a permeable felt belt, a permeable fabric belt and a permeable felt belt, or
4. d) a permeable felt press belt stretched around the roller 36, a permeable fabric belt and a permeable felt belt.

1. a) ein um die Walze 36 gespanntes permeables Pressband, ein permeables Gewebeband und ein permeables Filzband, oder
2. b) ein um die Walze 36 gespanntes permeables Pressband, ein permeables Siebband, ein permeables Gewebeband und ein permeables Filzband, oder
3. c) ein um die Walze 36 gespanntes permeables Pressband, ein permeables Filzband, ein permeables Gewebeband und ein permeables Filzband, oder
4. d) ein um die Walze 36 gespanntes permeables Filzpressband, ein permeables Gewebeband und ein permeables Filzband

If, on the other hand, the roller 36 of the belt press 34 is designed as a blowing roller, the belts wrapping around the roller 36 preferably comprise viewed in the flow direction of the drying fluid

1. a) a permeable press belt stretched around the roller 36, a permeable fabric belt and a permeable felt belt, or
2. b) a permeable press belt stretched around the roller 36, a permeable screen belt, a permeable fabric belt and a permeable felt belt, or
3. c) a permeable press belt stretched around the roller 36, a permeable felt belt, a permeable fabric belt and a permeable felt belt, or
4. d) a permeable felt press belt stretched around the roller 36, a permeable fabric belt and a permeable felt belt

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

Downstream of the belt press 34, the nonwoven material web is passed through at least one thermal drying device 46, such as in particular a TAD or air drying unit or a flat bed oven. The nonwoven material web can be dried in such a thermal drying device 46, in particular to the final dry content.

In the former 28, the fleece can advantageously be formed with a low consistency with a solids content of in particular 0.01 to 0.1% on a smooth forming screen or a structured forming screen that structures and / or perforates the fleece accordingly. In particular, a so-called inclined screen former or the like can be used for this.

The nonwoven can also be structured and / or perforated at the same time by the optionally provided water jet consolidation device 32. Such a water jet consolidation device 32 is therefore particularly preferred in those cases in which the nonwoven or the nonwoven material web is to be additionally structured and / or perforated.

The material input into the former 28 can i) at least partially from natural fibers, such as in particular from northern bleached kraft pulp (NBKP), hardwood pulp (LBKP), pulp from abaca fibers, cotton or the like, ii) at least partially from artificial fibers, in particular from Viscose or the like, iii) at least partially from synthetic fibers, such as in particular from polyester, polyamide or the like, iv) at least partially from mineral fibers, such as in particular glass fibers or the like, v) at least partially from carbon fibers and / or vi) from a mixture of any of the aforementioned substances.

Advantageously, the material input into the former 28 consists at least partially of fibers which are longer than 2 mm, preferably longer than 3 mm and particularly preferably longer than 4 mm. In particular for producing a nonwoven material web with a basis weight of greater than 50 g / m ² , preferably greater than 80 g / m ² and particularly preferably greater than 100 g / m ² , the nonwoven material web can be used before or after the belt press 34 be guided over a suction roller charged with vacuum.

Specifically, that in the Fig. 2 A schematic representation of the first exemplary embodiment of the device 30 for the production of nonwovens converted according to the invention, again a former 28, a water jet consolidation device 32, a belt press 34 and a thermal drying device 46, which in the present case is, for example, a TAD or air drying unit .

The fleece is formed in the former 28, for example by the wet process, with a low consistency on a forming fabric 48, which at the same time serves as a transfer belt for transferring the fleece to the water jet consolidation device 32. As indicated at "50", the fleece can be formed with an additional layer.

The fleece formed in the former 28 is transferred through the forming screen 48 in a closed train to the water jet consolidation device 32.

The consolidated nonwoven material web 52 is transferred by the water jet consolidation device 32, for example in an open pull, to the belt press 34, which is shown here, for example, with only two endless belts 40, 42 wound around the roller 36. The nonwoven material web 52 is transferred from this belt press 34, for example in an open train, to the thermal or TAD drying device 46.

Simultaneously with the mechanical pressurization of the nonwoven material web 52 by the belt press 34, a drying fluid is preferably pressed through the in this case permeable endless belts 40, 42 and through the nonwoven material web 52 by a corresponding pressure difference. In this case, the roller 36 has an open surface, and, as already mentioned, it can be designed in particular as a suction roller or as a blowing roller. In the exemplary embodiment shown, the hood 44 intended for dispensing or receiving the drying fluid is arranged above the roller 36. As shown, the roller 36 can be assigned a scraper 62.

The water jet consolidation device 32 is not mandatory. However, it can be provided in particular in the event that the nonwoven material web 52 is to be additionally structured and / or perforated. Such a structuring Perforation can take place, among other things, via the water jet consolidation device 32. In addition, in particular the belt press 34 can also be provided with at least one structured belt which structures and / or perforates the nonwoven material web 52 and which is correspondingly wound around the roller 36 again.

The Fig. 3 shows a schematic representation of another exemplary embodiment of a belt press 34 of the device converted according to the invention.

In the present case, the hood 44 for dispensing or receiving the drying fluid is arranged above the roller 36 of the belt press 34. In addition, in the exemplary embodiment shown, only an inner endless belt 40 and an outer endless belt 42 serving as a pressing belt 42 are wound around the roller 36 of the belt press 34.

In the present case, the loop of the inner endless belt 40 is arranged below the loop of the outer endless belt 42 serving as a press belt. The inner endless belt 40 can in particular again be a felt belt. The drying fluid flow is directed from top to bottom or from bottom to top, depending on whether the roller 36 is designed as a suction roller or as a blowing roller. The nonwoven material web to be dewatered again lies between the inner endless belt 40 and the outer endless belt 42. As already mentioned, the additional application of drying fluid to the nonwoven material web is optional. It is particularly preferred if the nonwoven material web is to be structured and / or perforated at the same time.

Even with the present in the Fig. 3 The embodiment shown can again be seen a scraper 62 assigned to the roller 36 of the belt press 34.

Like the one in particular Fig. 3 can be removed, the relevant endless belts 40, 42 are guided at the same wrap angle around the roller 36 of the belt press 34, the wrap angle advantageously being somewhat larger than the suction or blowing zone 64 of the roller of the belt press 34.

Reference list

10

conventional device

12th

Former

14

Water jet consolidation device

16

Intake pipe, suction box

18th

Drainage device

20th

thermal drying device (TAD)

22

Immersion bath

24

Winding device

26

Forming fabric

28

Former

30

contraption

32

Water jet consolidation device

34

Belt press

36

roller

40

inner (endless) band

42

outer (endless) band

44

(Drying) hood

46

thermal drying device (TAD)

48

Forming fabric

50

additional layer

52

Nonwoven material web

62

scraper

64

Suction or blowing zone

Claims (8)

1. Method for retrofitting a device for producing a non-woven material comprising a former (28) for forming a non-woven material, suction pipes and/or suction boxes (16) for dewatering the non-woven, as well as a drying installation (46) said method comprising the following steps:

   - R.emoving all suction pipes and/or suction boxes (16) disposed upstream of the drying installation (46) ; and

   - installing a belt press (34) between the former (28) and the drying installation (46), wherein the belt press (34) comprises a roller (36), at least one inner belt (40) that bears on the roller (36) and an outer press belt (42) being wrapped around said roller (36), wherein a non-woven material web (52) created from the non-woven formed in the former (28) is capable of being disposed, and preferably is disposed, between the inner belt (40) and the outer press belt (42) at least in the region of the roller (36), and wherein the press belt (42) is capable of being pressed, and preferably is pressed, against the roller (36) by way of a belt tension of at least 15 kN/m.
2. Method according to Claim 1,
   characterized in that the roller (36) of the belt press (34) by way of an open surface is embodied for dispensing or absorbing drying fluid, and the belts (40, 42) of the belt press (34) as belts (40, 42) that are permeable to drying fluid and preferably to air and/or water vapour are configured such that, simultaneously with the pressing of the non-woven material web (52) against the roller (36), on account of a pressure differential between the roller (36) and the outer press belt (42) a drying fluid can be allowed to flow through the permeable belts (40, 42) and the non-woven material web (52).
3. Method according to Claim 2,
   characterized in that the roller (36) of the belt press (34) is embodied as a suction roller such that the drying fluid, proceeding from preferably a drying fluid hood (44), can be suctioned into the suction rollers at least through the permeable outer press belt (42), the non-woven material web (52), and the permeable inner belt (40) .
4. Method according to Claim 2,
   characterized in that the roller (36) of the belt press (34) is embodied as a blower roller such that the drying fluid, proceeding from the blower roller, can preferably be blown to a hood (44) at least through the permeable inner belt (40), the non-woven material web (52), and the permeable outer press belt (42).
5. Method according to at least one of the preceding claims,
   characterized in that an installation (32) for consolidating the formed non-woven so as to form a non-woven material web is disposed between the former (28) and the belt press (34).
6. Method according to Claim 5,
   characterized in that the installation (32) is a mechanical consolidation installation, and preferably a water jet consolidation installation (32) .
7. Method according to at least one of the preceding claims,
   characterized in that the non-woven material web (52) is transferred in a closed draft from the former (28) to the belt press (34) and preferably up to the drying installation (46).
8. Method according to at least one of the preceding claims,
   characterized in that at least one thermal drying installation (46), preferably a through air drying (TAD) unit, or air drying unit, respectively, or a flat-bed oven, is provided downstream of the belt press (34).

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