WO2023104365A1

WO2023104365A1 - System and method for producing a single-layer or multi-layer nonwoven

Info

Publication number: WO2023104365A1
Application number: PCT/EP2022/076383
Authority: WO
Inventors: Bodo Heetderks; Sven Thomssen
Original assignee: Trützschler Group SE
Priority date: 2021-12-06
Filing date: 2022-09-22
Publication date: 2023-06-15
Also published as: DE102021132077A1; CN117500966A

Abstract

The invention relates to a system and a method, comprising - at least one carding machine (1), which is designed to generate a fibrous web (3) by means of an aerodynamic process, - a first conveying belt (4), which is designed to convey the fibrous web (3) from the carding machine to a compactor, - a compactor, which is designed to compact the fibrous web (3) to a nonwoven (24), - a drafting device (10), which is arranged downstream in the material-conveying direction and is designed to draw the nonwoven (24) by at least the factor of 1.5, - and a consolidator, which is arranged downstream in the material-conveying direction.

Description

Title: Plant and process for producing a single or multi-layer fleece

Description

The invention relates to a plant and a method for producing a single- or multi-layer nonwoven.

In the production of almost isotropic webs in the nonwovens sector from fibers that are used, for example, for wipes or hygiene articles, the carded fibrous webs are folded in a crosslapper to form a web with an MD/CD ratio of 1.3:1-2 ,1:1, which is further consolidated after the stacker. If, for example, a fleece with a weight of 40 g/m ² is to be produced as the end product, the carding machine produces a fibrous web with 30 g/m ² . This fibrous web runs into a subsequent fleece layer at a speed of 100 m/min, for example, and is folded there into four layers in order to produce the desired MD/CD ratio. The multi-layer fleece then runs at a speed of, for example, 22 m/min from the stacker into a drafting and bonding station, in order to then be wound up at a speed of 80 m/min. The lighter the fleece produced by the carding machine, the more sensitive the folding or cross-lapping process in the cross-lapper is, since air currents and high speeds have a very strong influence on the folding process. In addition, a compensating stacker is a very expensive investment for the plant operator, which takes up a lot of space due to the L-shape of the material flow and at the same time undesirably limits the production quality and quantity.

For example, from EP 0777771 B1 a device for the aerodynamic production of a fibrous web is known, which is also referred to as an airlay card. An almost isotropic fiber web can be produced with these airlay cards. A disadvantage is the low production speed with higher fleece weights.

The object of the present invention is to create a plant and a method for producing a single-layer or multi-layer nonwoven which can be used flexibly and with which almost isotropic nonwovens can be produced with high productivity.

The invention solves the problem set by the teachings of claim 1 and 12; further advantageous design features of the invention are characterized by the dependent claims. According to the technical teaching according to claim 1, the system for producing a single- or multi-layer nonwoven comprises at least one card, which is designed to produce a fibrous web by means of an aerodynamic process, a first conveyor belt, which is designed to transport the fibrous web from the card to a To transport compaction, wherein the compaction is designed to compress the fibrous web into a web.

Due to the aerodynamic production of the fibrous web, it has a high level of isotropy, which can otherwise only be achieved in the wetlaid or airlaid process. In contrast to these methods, a wide range of fiber lengths, fiber counts and fiber types can be processed with an airlay card, for example.

In order to efficiently further process the high mass of the fibrous web produced, the invention provides that a downstream drafting device is arranged in the material transport direction, which is designed to draft the fleece by a factor of at least 1.5. The fleece can then be consolidated in different ways.

The system is configured in such a way that an isotropic fleece can be produced with high productivity without a fleece layer. The productivity of the system is higher than when using a classic card with a subsequent fleece layer and the investments are significantly lower. With the end product having the same weight per unit area of, for example, 40 g/m ² , the productivity can be doubled according to the invention. Another advantage is the lower error rate in the manufacture of the nonwoven, since when thin nonwovens or fiber webs are folded, edges often turn over, resulting in a different accumulation of material across the cross section.

The system can have at least one additional card, which is designed to produce an additional fibrous web by means of an aerodynamic process. If there is enough space, any number of carding machines can be arranged in a row, the batt of which is further processed together. By varying the number of rollers used, the basis weight and productivity of the end product can be varied almost arbitrarily when the fleece is stretched by a factor of 1.5 to 4. The system is more flexible and less expensive than a system with a classic card and fleece layer. The same or a different fiber quality can be used.

In the case of several carding machines arranged in a row, the conveyor belt for transporting the fibrous web from the first carding machine in the material transport direction can be arranged at least partially below the other carding machines. The conveyor belt can be guided under the floor or arranged between the supports of the roller cards.

Before the compaction, a separate conveyor belt can be arranged, which is designed to receive the fibrous webs in layers one on top of the other. It is not necessary to synchronize the separate conveyor belt and the take-off belts of the cards with each other. Because the cards are designed as airlay cards, a compact and space-saving card can be used. Compared to other carding machines that work according to the random fleece principle or the aerodynamic process, the airlay card can produce a fiber web with a low basis weight and process fibers with a large variation in length.

The compaction can be designed, for example, as at least one pair of rollers, with which the fibrous web is compacted without changing the structure or orientation of the fibers. The downstream drafting device has at least one upper and lower drafting arrangement, with which the fleece can be stretched by a factor of 1.5 to 4. This can consist of an arrangement of rollers or conveyor belts, each of which has a smooth surface, or it can be fitted with needles or fittings.

The system can be made more flexible by arranging at least one unwinding station in the material transport direction after the drafting device and before the consolidation, which is designed to insert, for example, another carded fleece or a layer of paper or tissue below and/or above the fleece into the introduce plant. The result is a very flexible system in which different fibers with different fiber lengths and different basis weights can be introduced and processed individually or together.

The subsequent consolidation can be in the form of hydrodynamic consolidation or thermobonding. The hydrodynamic bonding is designed as water jet bonding and has several water beams with associated suction, which can be operated at a pressure of 40 to 400 bar. A single fleece or several layers of fleece can be bonded, bonded and/or structured with one another by means of hydroentanglement. By means of a specially designed nozzle arrangement or in combination with an upper structuring belt, with which the web as fibrous material and/or the nonwoven is chambered, a structuring and thus a patterning surface of the nonwoven is possible. Alternatively, the solidification and structuring can also take place on a drum (not shown) with a structured shell that is mounted in front of the dryer.

After the hydrodynamic consolidation, a dryer can be arranged in the material transport direction.

The method according to the invention for producing a single- or multi-layer nonwoven provides, from fibers with a fiber length of 10 to 60 mm and a fiber fineness of 0.5 to 30 dtex, by means of an aerodynamic process, at least one fiber web with an MD/CD ratio of 1 .0:1 to 1.2:1 to generate. The fiber web is then compacted and that resulting nonwoven stretched by a factor of at least 1.5 and then solidified. The method according to the invention makes it possible to produce an isotropic fleece without a fleece layer with high productivity. By stretching the fleece, an isotropic fleece can be produced with almost any basis weight at high production speeds. Compared to the wetlaid or airlaid process, the process effort is significantly lower and a greater variety of fibers in terms of length, fineness and type can be processed.

The fact that at least one second additional fiber batt is produced, which is laid down on the first fiber batt and compacted together with it to form a fleece, can further increase the productivity of the plant. Any number of fiber webs can be produced separately, placed one on top of the other and adjusted to the final weight by stretching. The concept is essentially only limited by the space requirement for more than four cards in one line.

The fibrous webs arranged one on top of the other preferably all have the same properties as the first fibrous web. However, the invention also provides the possibility of producing fiber webs of different fiber quality and processing them together, with both fiber webs having approximately the same isotropy.

The fibrous web can be stretched by a factor of 1.5 to 4, preferably by a factor of 2.

For example, the batt of each card can have a basis weight of 20 to 400 g/m ² and be produced at a speed of 15 to 200 m/min, preferably have a basis weight of 80 g/m ² and be produced at a speed of 80 m/min.

The method can be made more flexible by solidifying the stretched nonwoven together with at least one other nonwoven, which is introduced into the system by means of an unwinding station. The additional fleece, which can consist of a carded fleece or a layer of paper or tissue, for example, can be arranged above and/or below the fleece. The stretched nonwoven can thus be covered or chambered on one side with a different, preferably lighter nonwoven quality, so that a large selection of hygiene products, for example, can be produced.

The stretched web can be consolidated either alone or in combination with the web(s) introduced from the unwinding station(s) hydrodynamically or thermally, depending on the type of fiber. Further measures improving the invention are presented in more detail below together with the description of a preferred exemplary embodiment of the invention with reference to the figures.

Show it:

Fig.1: shows a first embodiment of the system according to the invention and of the

procedure;

2a: shows a detailed view of a first embodiment of a delay device;

2b: shows a detailed view of a second embodiment of a delay device;

Fig. 3 shows a second embodiment of the system according to the invention and of the

procedure.

The system 100 according to the invention comprises at least one first card 1, which can be designed as an airlay card. The card 1 is fed via a feeder 2 with fibers or fiber tufts, which can consist of natural or synthetic fibers (cotton, viscose, lyocell, hemp, pulp, polyester, polyamide, polypropylene, polyolefin) or mixtures of these fibers. Fibers with a length of 10 to 60 mm and 0.5 to 30 dtex can preferably be processed. The working width of card 1 can be between 1.5 and 3.8 m. The fibrous web 3 produced, which has a weight of 80 g/m ² at a production speed of 80 m/min, for example, is placed on a first conveyor belt 4 that directs the fibrous web 3 to a compaction, which in this exemplary embodiment is designed as a pair of rollers 6 is. The compaction has the task of densifying the fiber web without changing the structure in the orientation of the fibers.

Other aerodynamic methods can also be used to produce a random web, with which a fibrous web with high isotropy can be produced in the dry process. Airlay carding has the advantage that fibers of different lengths and types (natural/synthetic fibres) can be processed in a wide processing range (fleece weight, fiber fineness) with high quality.

As an alternative to the pair of rollers 6, the compaction can also take place by means of a roller and a circulating belt, the roller then preferably being designed as a perforated plate roller. A further alternative to compaction can be hydromechanical pre-consolidation, which has the advantage that the slightly pre-consolidated fleece can later be drawn out more evenly. If a higher basis weight is required for the end product, the system 100 has at least one additional card 1a, which can also be designed as an airlay card. In this exemplary embodiment, the fibrous web 3 of the first card 1 is guided by means of the conveyor belt 4 under the cards 1a that follow in the material transport direction and is transferred to a further conveyor belt 5 . The second card 1a is also fed via a feeder 2a with fibers or fiber tufts, which can be identical to the fibers of the first card 1. However, the fibers can also differ, so that a multi-layer fleece can be produced with layers of different fibers. In this exemplary embodiment, the second fibrous web 3a produced also has a weight of 80 g/m ² at a production speed of 80 m/min. The second fibrous web 3a is also transferred to the conveyor belt 5, on which the two fibrous webs 3, 3a are guided together. A synchronization of the conveyor belts 4, 5 is not necessary. The subsequent compaction, in which two fiber webs 3, 3a run in with a total of 160g/m ² at 80m/min, is designed as a pair of rollers in this exemplary embodiment and compacts the two layers of fiber web 3, 3a without changing the orientation of the fibers , so that a fleece 24 is formed. Since the end product should have a weight of 40 g/m ² , a drafting device 10 is arranged after the compaction, which can be designed as a web stretcher.

In a first embodiment according to FIG. 2a, the drafting device 10 is designed as a fleece stretcher, which can have an inlet area 11 with two conveyor belts set at an angle to one another. The angle of the conveyor belts placed in relation to one another can be adjustable, as can the speed of each individual conveyor belt. The web 24 is pre-compacted and reduced in thickness in the conveyor belts that are positioned in relation to one another, so that it can enter between the upper and lower drafting arrangements 12, 13. Both drafting arrangements 12, 13 consist of a row of rollers which are offset from one another, so that the rollers of the upper drafting arrangement 12 at least partially protrude into the gusset of the rollers of the lower drafting arrangement 13. At least some of the rollers are driven, with the two drafting arrangements 12, 13 being operated at different roller speeds, so that the fleece is stretched between the rollers. The speed of the rollers can increase continuously from the entry area 11 to the exit area 14 . For this purpose, the rollers preferably have individual drives, so that the draft can be variably adjusted along the drafting device. The mass of the fleece 24 in the cross section can be reduced via the difference in speed of the rollers from the inlet area 11 to the outlet area 14, so that the fleece 24 is stretched essentially uniformly over the entire cross section. Preferably, the upper draft assembly 12 is force or weight loaded. The distance between the upper draft arrangement 12 and the lower draft arrangement 13 can preferably decrease from the inlet area 11 to the outlet area 14 . The Outlet area 14 of the drafting device 10 can be designed as a conveyor belt which is adapted to the increased transport speed of the fleece.

Preferably, the surfaces of the rollers of the upper and lower drafting arrangement 12, 13 can be smooth or have a set or needles, with which a shrinkage of the web can be avoided. Lateral guides on the drafting device 10 prevent the web 24 from being drafted beyond the desired working width.

FIG. 2b shows a second embodiment of a drafting device 10, which can also have an inlet area 11 with two conveyor belts set at an angle to one another. The angle of the conveyor belts placed in relation to one another can be adjustable, as can the speed of each individual conveyor belt. The web 24 is pre-compacted and reduced in thickness in the conveyor belts that are positioned in relation to one another, so that it can enter between the upper and lower drafting arrangements 12, 13. In this exemplary embodiment, the upper and lower drafting arrangement 12, 13 is designed as a conveyor belt, with the conveyor belts being operated at different speeds, so that the fleece is stretched between the conveyor belts by a factor that can be 2, for example. The upper and lower draft arrangement 12, 13 can also be adjusted in angle and/or at a distance from one another in order to enable adaptation to the different web thicknesses. Particularly in this exemplary embodiment, in which the respective speed of the upper and lower drafting arrangement 12, 13 remains the same over the drafting section, the outlet area 14 is designed as a conveyor belt and can be set to different speed ranges according to the stretching factor. Preferably, the conveyor belts of the drafting arrangement 12, 13 can also be provided with needles on the surface facing the web 24.

After the drafting device, the web 24, which was stretched in the drafting device 10 by a factor of 2, for example, is bonded with a weight of 40 g/m ² at a speed of 160 m/min, which can take place in the subsequent hydrodynamic bonding. This has several water beams 20 in which the fibers are woven together by means of water jets. Below the water bar 20, a circulating conveyor belt 21 can be arranged, under which a suction device 22 is arranged. The conveyor belt 21 is perforated in order to discharge the water from the water bars 20. As an alternative to this embodiment, the fleece 24 can also be chambered between two conveyor belts and solidified by means of water jets. The fleece can not only be consolidated, but can also be structured and/or perforated. Another alternative to this embodiment shown can be done by solidification on a rotating drum and sucked from the inside, in which the fleece 24 next to the Solidification is also structured and / or perforated. Depending on the application, the water beams can be operated with a water pressure of 40 - 400 bar. After the bonding device, the fleece 24 is dried in a dryer, which can be designed as a drum or belt dryer, and wound up at a winding station 25 .

An alternative embodiment of the system 100 is shown in FIG. 3, in which at least one or two unwinding stations 15 are arranged after the drafting device 10 . These are then designed to guide a thin layer of synthetic carded nonwoven 15a into the system below and/or above the nonwoven 24, so that the nonwoven 24 made of isotropic fibers is covered with one or two further layers of carded nonwoven 15a. The layers of the thin synthetic carded fleece 15a can, for example, have a low weight per unit area of <30 g/m ² . As an alternative to the synthetic carded fleece 15a introduced through the unwinding stations 15, a thin fleece made of tissue or paper can also be used.

According to this exemplary embodiment, the system is designed to produce a single or multi-layer fleece 24, which can consist only of the fibrous web 3, 3a of the card 1, 1a, or of the fibrous web 3, 3a with a lower and/or upper carded fleece 15a. This results in material combinations of fibers with different basis weights with different numbers of fiber layers and/or one to three plies. The system 100 is configured in such a way that an isotropic fleece 24 can be produced with high productivity without a fleece layer. The MD/CD ratio after solidification is between 1.5:1 to 2.1:1.

Reference sign

100 plant

1 , 1a clutter

2, 2a feeders

3, 3a batt

4 conveyor belt

5 conveyor belt

6 reels

10 delay device

11 inlet area

12 upper draft arrangement

13 lower draft arrangement

14 run-out area

15 unwind station

15a carded web

20 water bars

21 conveyor belt

22 suction

23 dryers

24 fleece

25 changing station

Claims

patent claims

1. Plant (100) for the production of a single- or multi-layer fleece, comprising

- At least one card (1), which is formed by means of an aerodynamic

method of producing a fibrous web (3),

- a first conveyor belt (4) which is designed to transport the fibrous web (3) from the card (1) to a compactor,

- wherein the compacting is designed to compress the fibrous web (3) into a fleece (24), characterized in that

- A downstream stretching device (10) is arranged in the material transport direction, which is designed to stretch the fleece (24) by a factor of at least 1.5,

- and a downstream consolidation in the direction of material transport.

2. Installation according to claim 1, characterized in that the installation (100) has at least one additional card (1a) which is designed to produce an additional fibrous web (3a) by means of an aerodynamic process.

3. Plant according to claim 2, that the conveyor belt (4) is arranged at least partially below the further roller card (3a).

4. Plant according to claim 2, that a conveyor belt (5) is arranged in front of the compaction, which is designed to receive the fibrous webs (3, 3a) in layers one on top of the other.

5. Plant according to claim 1 to 2, that the cards (3, 3a) are designed as airlay cards.

6. Plant according to claim 1, characterized in that the compaction is designed as at least one pair of rollers (6) or as a roller with a rotating belt or as hydromechanical consolidation.

7. Plant according to claim 1, characterized in that the consolidation is designed as a hydrodynamic consolidation or as a thermal bonder.

8. Plant according to claim 1, characterized in that the delay device (10) have at least one upper and lower delay arrangement (12, 13), each consisting of rollers or conveyor belts.

9. Plant according to claim 8, characterized in that the delay arrangement (12, 13) is equipped with needles or fittings.

10. Plant according to claim 7, characterized in that a dryer (23) is arranged in the material transport direction after the hydrodynamic solidification.

11. Plant according to Claim 1, characterized in that at least one unwinding station (15) is arranged in the material transport direction after the drafting device (10) and before the consolidation, which is designed to unwind a fleece (15a) below and/or above the fleece (24 ) to introduce into the system (100).

12. A process for producing a single- or multi-layer fleece, in which at least one fibrous web (3) with an MD/CD- Ratio of 1.0:1 to 1.2:1 is produced, which is compacted and the resulting web (24) is stretched by a factor of at least 1.5 and then solidified.

13. The method according to claim 12, characterized in that at least a second further fibrous web (3a) is produced, which is laid down on the first fibrous web (3) and compacted together with this to form a fleece (24), the second further fibrous web ( 3a) has the same properties as the first batt (3).

14. The method according to claim 12 or 13, characterized in that the solidification takes place hydrodynamically or thermally.

15. The method according to claim 14, characterized in that the hydrodynamic solidification takes place by means of water jets at 40 to 400 bar.

16. The method according to claim 15, characterized in that the fleece (24) has an MD/CD ratio of between 1.5:1 and 2.1:1 after consolidation.

17. The method according to claim 12, characterized in that the fibrous web (3) has a basis weight of 20 to 400 g/m ² and is produced at a speed of 15 to 200 m/min, preferably has a basis weight of 80 g/m ² and with is produced at a speed of 80m/min.

18. The method according to claim 12, characterized in that the stretching is carried out by a factor of 1.5 to 4, preferably by a factor of 2.

19. The method according to any one of claims 12 to 18, characterized in that the stretched fleece (24) is consolidated together with at least one other fleece (15a), the fleece (15a) being arranged below and/or above the fleece (24). is.