WO2013160134A1

WO2013160134A1 - Method and device for melt-blowing, forming and plaiting finite fibres to produce a fibrous nonwoven

Info

Publication number: WO2013160134A1
Application number: PCT/EP2013/057777
Authority: WO
Inventors: Günter SCHÜTT; Bernhard Potratz; Jens Neumann-Rodekirch; Anthony Barber
Original assignee: Oerlikon Textile Gmbh & Co. Kg
Priority date: 2012-04-27
Filing date: 2013-04-15
Publication date: 2013-10-31
Also published as: CN104246045A; CN104246045B; EP2841634A1; EP2841634B1

Abstract

The invention relates to a method and a device for melt-blowing, forming and plaiting finite fibres to produce a fibrous nonwoven. Here, the fibre streams which are produced by a melt-blowing die and a hot air flow are blown into a forming gap of a forming element, wherein the fibres are joined together within the forming gap to produce a fibre composite. In order to influence the filling and the forming of the fibres within the forming gap directly below the melt-blowing die, according to the invention the fibres are freely guided substantially vertically from the melt-blowing die as far as the forming gap via an adjustable blowing section, wherein the adjustability of the blowing section lies in the range from 100 mm to 2000 mm. In this way, both very fine fibres and coarse fibres can advantageously be formed to produce a loose fibre composite.

Description

Method and apparatus for melt blowing, forming and depositing finite fibers into a nonwoven fabric

The invention relates to a method for melt blowing, forming and depositing finite fibers to a nonwoven fabric according to the preamble of claim 1 and to an apparatus for melt blowing, forming and depositing finite fibers into a nonwoven fabric according to the preamble of claim 7. For the production of fiber nonwoven fabrics from synthetic fibers In principle, two different methods and devices are known in the art. Both methods differ both in the production of the fibers and in the deposition of the fibers to a nonwoven fabric. With the variant known in the art as a meltblown process, freshly extruded fibers are drawn off directly from the nozzle openings of the meltblowing die by a hot air stream by means of a hot air stream and fed as a fiber stream to a nonwoven fabric. Essentially finite fibers occur which have a relatively high elasticity. From this variant, the invention proceeds, as will be explained later.

In a second variant, which is referred to in the art as a so-called spunbond process, synthetic filaments are extruded by means of a spinneret and cooled. Subsequently, the filaments are fed by means of a supplied compressed air as a fiber stream to a nonwoven fabric. Here, the nonwoven fabric consists essentially of endless filaments with higher strengths. For depositing the filaments, a compressed air flow generated by the additional extraction device is used, which can be set individually to the respective process. In contrast, in the meltblown process, the stream of hot air generated at the meltblowing die is used to pull out the extruded fibers and lay down the fibers. The filing of the fibers can be done directly on screen belts or sieve drums, are accumulated on the surfaces of the fiber stream and merged into a fiber composite. In order to produce particularly loosely structured fiber webs, it is also known to receive the fiber stream by means of a Formierspaltes and merge to form a fiber composite. Such a method and such a device are known for example from DE 30 41 089 AI. In this case, two forming elements are arranged below the melt-blowing nozzle, which form a formation between them. The formation s gap is held centrally to the melt-blowing nozzle, so that the fiber flow is directed directly to the formation s gap. A disadvantage of such a deposition of the fibers is that a part of the air flow acts directly on the composite sections deposited in the formation s gap. In the conventional trays of the fiber stream on Siebflä- chen, the air flow is absorbed and removed through the screen surface. This can be realized in the deposition of the fiber stream in a formation s gap only on the laterally arranged forming elements. It is an object of the invention to develop a generic method and a generic device for melt blowing, forming and depositing finite fibers to form a nonwoven fabric such that also finest fibers in a formation s gap can be formed into a loose fiber composite.

Another object of the invention is to improve the known method and the known apparatus for melt blowing, forming and depositing finite fibers to a nonwoven fabric such that highly voluminous nonwoven fabrics with small to large basis weights are flexible to produce. This object is achieved according to the invention in that the fibers are guided essentially vertically vertically from the melt-blowing nozzle to the formation gap via an adjustable blowing line, the setting range of the blowing line being in the range from 100 mm to 2,000 mm. Advantageous developments are defined by the features and feature combinations of the respective subclaims.

The invention is characterized in that the hot air flow required to produce the fibers can be selected at the melt-blowing nozzle independently of the deposition of the fibers in the formation s gap. In order to bring the intensity of the air flow during storage in a size advantageous for the formation, the blowing distance can be shortened or extended as required. The blowing line below the melt-blowing nozzle and the formation gap can advantageously be oriented vertically, so that a 3D structure of the fiber composite can be formed during deposition and formation. In order to form a fiber composite with high uniformity, is provided according to an advantageous embodiment of the invention that the fibers are blown for forming between two oppositely rotating drums with air-permeable drum walls, which form drums between the formation s gap and which each with a same peripheral speed be driven in the range of 0.1 m / min to 50 m / min. By adjusting the peripheral speeds of the drums, the surface densities of the fiber volume can be advantageously influenced. Thus, very loose fiber webs can be produced with an increased peripheral speed of the drum walls in the formation gap.

For both the method according to the invention and for the device according to the invention, it has proved particularly useful that the fiber composite, after being formed by one of the drums, be deposited on the nonwoven fabric on a screen belt which discharges the fiber web tangentially to the drums. Thus, further treatments on the nonwoven fabric can be carried out in a short sequence. The thickness of the produced nonwoven fabric is determined essentially by a forming cross section of the forming nip. The adjustment of the formation gap is done in a simple manner such that a distance between the drums is adjusted symmetrically or asymmetrically between the drums in a range of 1 mm to 100 mm. In an asymmetric adjustment, the center axis of the formation gap no longer coincides with the center of the meltblowing die. In addition, deposition effects and formations within the formation gap can thereby be generated. To form an asymmetric formation gap, it is also possible to form the formation gap between two drums having different drum diameters. According to an advantageous development of the device according to the invention, the drums can have identical or different drum diameters with a diameter ratio in the range from 0.5 to 2.0. This can advantageously produce different surface structures on the nonwoven fabric. The drums have for this purpose a drum diameter which is in the range of 100 mm to 800 mm.

On the one hand to influence the deposition of the fibers on the inlet side of the forming gap by receiving the blowing air and on the other hand to carry out the removal of the nonwoven fabric at least one of the drums, the device according to the invention is to be improved such that one of the drums has an inner suction chamber with a negative pressure source is connected and which is shielded by the air-permeable drum wall to the environment. In that regard, additional suction streams can be generated to assist in the generation and guidance of the fibrous web. The effect can be further supported by idem both drums each having a separate suction chamber, which are connected together to a vacuum source or separately with two vacuum sources.

Particularly advantageous, the development of the invention has been found, in which an angular position of the suction chamber on the circumference of the drum is adjustable. Thus, the position of the suction chamber can be freely selected relative to the inlet and outlet of the Formierspaltes. The method according to the invention and the device according to the invention will be explained in more detail below with reference to some embodiments of the device according to the invention with reference to the attached figures.

They show:

Fig. 1 shows schematically a cross-sectional view of a first embodiment of the device according to the invention for melt blowing, forming and depositing finite fibers to a nonwoven fabric

Fig. 2 shows schematically a cross-sectional view of another embodiment of the device according to the invention for melt blowing, forming and depositing finite fibers

3 schematically shows a cross-sectional view of a further embodiment of the device according to the invention for melt blowing, forming and depositing finite fibers

Fig. 4 shows schematically another embodiment of the device according to the invention for melt blowing, forming and depositing finite fibers

In Fig. 1, a first embodiment of the device according to the invention is shown schematically in a cross-sectional view. The exemplary embodiment has a melt-blowing nozzle 1 and a forming element 2 held below the melt-blowing nozzle 1. The forming element 2 is formed by two oppositely driven drums 3, which form a formation s gap 6 between them. The formation s gap 6 extends between the drums 2.1 and 2.2 in the vertical direction, the drums 2.1 and 2.2 symmetrical to a longitudinal axis of the Schmelzblasdüse 1 are held. The drives of the drums 2.1 and 2.2 are not shown here in detail and can be performed by a group drive or individual drives. The drums 2.1 and 2.2 each have an air-permeable drum wall 3, which rotate in opposite directions in the fiber blowing direction with the peripheral speed predetermined by the drive of the drums 2.1 and 2.2.

The melt-blowing nozzle 1 is arranged vertically adjustable above the drums 2.1 and 2.2 in a machine frame 13. In this case, the melt-blowing nozzle 1 comprises at least one row of nozzle channels 10 arranged in the center plane and interacting on one outlet side with air nozzles 11.1 and 11.2 for producing a fiber stream 7. The air nozzles 11.1 and 11.2 are each assigned two compressed air chambers 12.1 and 12.2, which are connected to compressed air source, not shown here. The nozzle channels on the melt-blowing nozzle 1 extend over a maximum length of seven meters. Accordingly, the drums 2.1 and 2.2 for forming the formation gap 6 also have a length in the range of seven meters. This is also referred to as a so-called working width, in which a nonwoven fabric is formed continuously from synthetic fibers.

In order in particular to influence the depositing and the formation of the fibers in the forming gap 6, the meltblowing die 1 can be adjusted at different heights on the machine frame 13 so that a free blown line is formed between the meltblowing die 1 and the forming gap 6. The free blowing line is marked in FIG. 1 with the letter B and determined by the distance between the bottom of the melt-blowing nozzle 1 and the top of the drums 2.1 and 2.2. Depending on fiber types and fiber processes, the blowing range can be adjusted in steps of 100 mm to 2,000 mm in steps or steplessly. Thus, the fiber streams arriving directly into the formation s nip can be influenced without additional means.

In the exemplary embodiment illustrated in FIG. 1, the fiber fleece is discharged through the drum wall 3 of the drum 2.2 immediately after it leaves the formation s nip 6. For this purpose, a suction chamber 4 is formed on the outlet side of the drum 2.2, which is coupled to a vacuum source 5. Via the suction flow generated from the environment, a forced guidance of the fiber fleece is achieved so that the fiber fleece can be deflected and removed directly tangentially to the drum 2.2. The blown air forming the fiber stream can advantageously be taken up and removed via the suction chamber 4 and the vacuum source 5. To support the removal of the blowing air could also be formed on the opposite drum 2.1, a second suction chamber, which would be connected to a vacuum source.

In Fig. 1, the possible formation of a second suction chamber is shown in a dashed line on the drum 2.1. The suction chamber 4 'of the drum 2.1 and the suction chamber 4 of the drum 2.2 each have an offset angular position on the drum 2.1 and 2.2 in order to influence the fiber deposition and the discharge of the blowing air. The angular position of the suction chamber 4 and 4 'could be made adjustable on the circumference of the drums 2.1 and 2.2. This achieves high flexibility for fiber deposition. Thus, the suction chambers 4 and 4 'could be arranged offset from each other to the forming gap 6 - as shown in Fig. 1 - or be set opposite to the drums 2.1 and 2.2. In the embodiment shown in Fig. 1, in which only the drum 2.1 has a suction chamber 4, the angular position of the suction chamber 4 on the circumference of the drum 2.2 in both clockwise and counterclockwise adjustable. In that regard, in particular, the region at the inlet of the forming gap 6 or the region at the outlet of the forming gap 6 can be sucked.

In the embodiment shown in Fig. 1, the drum 2.1 and 2.2 are carried out with the same size drum diameter. The drum diameter is entered with the code letters Di and D ₂ . In this case, Di = D ₂ . The drum diameter of the drums 2.1 and 2.2 may in this case be in a range of 100 mm to 800 mm. The formed by the drums 2.1 and 2.2 formation s gap 6 has a forming cross-section, which is determined by the distance of the two drums 2.1 and 2.2. The distance between the drums is indicated in Fig. 1 with the capital letter F. The distance F between the drums 2.1 and 2.2 can be changed by moving one of the drums 2.1 or 2.2 or both drums 2.1 and 2.2. Thus, with simultaneous displacement of both drums 2.1 and 2.2 symmetrical cross-sectional changes of the forming gap 6 can be adjusted, a one-sided displacement of the drums 2.1 or 2.2 can also be advantageous asymmetric adjustments with respect to the center axis of the melt-blowing 1. An asymmetrical configuration of the forming gap is shown for example in the embodiment of FIG. 3. The embodiment of FIG. 3 is identical to the embodiment of FIG. 1, so that only the differences are explained below. In the in Fig. 3 illustrated embodiment, the drum 2.1 is formed with a smaller drum diameter. In that regard, the drum diameter Όι the drum 2.1 is smaller than the drum diameter D _{2 of} the drum 2.2. The diameter ratio of the drum diameter of the drums 2.1 and 2.2 to form different forming column is in the range Ό ₁ ίΌ ₂ = 0.5 - 2.0. This provides additional flexibility to obtain possible effects in the formation of the fibers.

In the exemplary embodiments illustrated in FIGS. 1 and 3, a polymer melt is fed to the melt-blowing nozzle by means of a melt source, not shown here. By one or more pumps, the melt is passed under pressure through the nozzle channels 10 of the melt-blowing nozzle 1. On the outlet side of the melt-blowing nozzle 1, a hot air flow is generated by the air nozzles 11.1 and 11.2, which together with the fibers emerging from the nozzle channels 10 blown into the blowing line. The generated fiber stream 7 is aligned vertically and meets at the end of the blowing line B on the formation s gap 6 and the drum walls 3 of the drums 2.1 and 2.2. About the rotational movement of the drums 2.1 and 2.2, the fibers are guided in the formation s gap 6 and formed into a fiber composite 8. The formation takes place essentially through the forming cross section of the forming gap 6, so that a finished nonwoven fabric 9 is already present on the outlet side of the drums 2.1 and 2.2. The fiber fleece 9 is taken from the drum 2.2 after leaving the formation s gap 6 and removed. The drum speeds of the drum 2.1 and 2.2 are set synchronously and can be in a range of peripheral speed of 0.1 to 50 m / min. be adjusted continuously. In Fig. 2, another embodiment of the device according to the invention for melt blowing, forming and depositing synthetic fibers is shown schematically in a cross-sectional view. The embodiment is substantially identical to the embodiment of FIG. 1, so that only the differences will be explained at this point and otherwise reference is made to the above description.

In the embodiment shown in FIG. 2, the melt-blowing nozzle 1 is identical to the exemplary embodiment according to FIG. 1. Below the melt-blowing nozzle 1, the drums 2.1 and 2.2 are arranged in a guide frame 15 as the forming element 2. The drums 2.1 and 2.2 can be continuously adjusted together in position on the guide frame 15 wherein on the one hand between the Schmelzblasdüse 1 and the formation s gap 6 formed Blas stretch B and on the other hand between a screen belt 4 and the drum 2.2 formed storage height A. change. The storage height is entered in Fig. 2 with the code letter A. The screen belt 14 below the drums 2.1 and 2.2 is guided over a plurality of guide rollers 16 such that the nonwoven fabric tangentially from drums 2.1 and 2.2 can be removed. Due to the adjustment between the drums 2.2 and the screen belt 14, it is additionally possible to form an additional forming zone for the nonwoven fabric.

The drums 2.1 and 2.2 are driven in opposite directions together via an electric motor 19. For this purpose, the drive axles of the drive belts 2.1 and 2.2 are connected to one another via a belt 20 and pulleys 21. The direction of rotation of the drums 2.1 and 2.2 is rectified to the fiber stream 7, which arrives in the formation s gap 6. To that extent far can be about the peripheral speed of the drum 2.1 and 2.2 control the recording of the fibers in the formation s gap.

The function of the embodiment of the device according to the invention shown in FIG. 2 is identical to the aforementioned embodiment of FIG. 1. Only the filament of the nonwoven fabric is deposited on the screen belt arranged below the drums 2.1 and 2.2. In this case, larger storage heights A can be adjusted so that the fiber composite emerging from the forming gap 6 initially separates from the drums and is then deposited freely on the wire belt. For receiving and removing the blast air, one or both drums could be equipped with a suction chamber, as described in the embodiment of FIG. 1. The illustrated in Fig. 2 embodiment of the device according to the invention is also particularly suitable to produce composite nonwovens. Thus, from Fig. 4 shows a further embodiment of the device according to the invention, in which a plurality of melt-blowing nozzles are arranged side by side to merge several fiber webs to form a composite nonwoven. In the exemplary embodiment illustrated in FIG. 4, a total of three blowing stations 17.1, 17.2 and 17.3 are shown, each of which shows a melt-blowing nozzle. In the first two blowing stations 17.1 and 17.2, the fiber streams are taken up by a formation s gap and formed and then deposited on the screen belt 14. Here are between the formation s columns 6 and melt-blowing nozzles 1 of the blowing stations 17.1 and 17.2 set different blown sections. The second blowing station 17.2 is identical to the first blowing station 17.1, so that a second nonwoven fabric is deposited on the surface of the screen belt 14 which forms a composite with the first nonwoven fabric. The third blowing station 17.3 shows a melt-blowing nozzle 1, which is arranged at a short distance above the sieve belt 14. On the opposite side of the screen belt 14, a suction device 18 is formed, which would serve to Aufnahme the fiber flow on the surface of the screen belt 16. In that regard, the nonwoven fabric produced by the blowing station 17.3 is deposited directly on the surface of the screen belt 14 and forms a composite nonwoven with the already existing fiber webs. The inventive method and the device according to the invention are suitable for all spinnable materials such as polyolefins (eg polyethylene, polypropylene, polyoctene, polymerized cycloalkenes), aliphatic, cycloaliphatic and partially aromatic polyesters, aliphatic and aromatic polyamides, polyarylene sulfides and polyarylene oxides, polyoxymethylene, polycarbonates Thermopiatic polyurethanes or reactive resins (such as melamine resin, phenolic resin, epoxy resin) to process. Due to the adjustability of the blowing line, these materials can advantageously be produced at very different fiber strengths to very loose fiber webs. The formation within the formation gap can be carried out with high uniformity and constancy.

Reference sign list

meltblowing

Forming element.1, 2.2 Drum

drum wall

, 4 'suction chamber

, 5 'negative pressure source

forming gap

fiber stream

fiber composite

Fiber fleece0 nozzle channel

1.1, 11.2 Air nozzles

2.1, 12.2 Compressed air chamber

3 machine frame

4 screen belt

5 guide frame

6 leadership role

7.1, 17.2, 17.3 Blas station

8 suction device

9 engine

0 belt

1 pulley

Claims

claims

A method of melt blowing, forming and depositing finite fibers into a nonwoven fabric wherein the fibers produced by a meltblowing die are blown into a forming air with a hot air stream and wherein the fiber composite formed by the forming nip is formed on an outlet side of the forming nip Fiber fleece is discharged,

characterized in that

the fibers from the meltblowing die to the forming s gap are guided essentially vertically vertically over an adjustable blowing distance, wherein the adjustment range of the blowing line is in the range of 100 mm to 2000 mm.

Method according to claim 1,

characterized in that

the fibers are blown for forming between two oppositely rotating drums with air-permeable drum walls, which drums form between them the formation gap and which are each driven at a same peripheral speed in the range of 0.1 m / min to 50 m / min.

Method according to claim 2,

characterized in that

the fiber composite is deposited after forming by one of the drums to the nonwoven fabric on a screen belt, which discharges the nonwoven tangentially to the drums.

4. The method according to claim 1 or 2,

characterized in that

to set a forming cross section at the forming nip, a distance between the drums is adjusted in a range of 1mm to 100mm symmetrically or asymmetrically between the drums.

5. The method according to any one of claims 1 to 4,

characterized in that

the fibers are blown into a symmetrical or asymmetric forming nip, the drums having identical or different drum diameters with a diameter ratio in the range of 0.5 to 2.0.

6. The method according to claim 5,

characterized in that

the drum diameter of the drums is in the range of 100 mm to 800 mm.

7. Apparatus for meltblowing, forming and depositing finite fibers into a nonwoven fabric, comprising a meltblowing die (1) for producing a fiber stream and at least one forming element (2) for forming a forming nip (6) in which the fibers form a fiber composite and be discharged, characterized in that

an adjustable free blowing line (B) is formed between the melt-blowing nozzle (1) and the formation gap (6), wherein the blowing line (B) is vertically aligned and by a height adjustment of Schmelzblasdüse (1) and / or the forming element (2) in the range of 100 mm to 2000 mm is adjustable.

8. Apparatus according to claim 7,

characterized in that

the formation s gap (6) between two drums (2.1, 2.2) is formed with air-permeable drum walls (3) which are driven in opposite directions with a peripheral speed in the range of 0.1 m / min to 50 m / min.

9. Apparatus according to claim 8,

characterized in that

below the drums (2.1, 2.2) is arranged a running sieve belt (14), wherein the sieve belt (14) discharges the fiber fleece tangentially to the drums (2.1, 2.2).

10. Apparatus according to claim 8 or 9,

characterized in that

for setting a forming cross-section (F) at the forming gap (6) a distance between the drums (2.1, 2.2) in a range of 1mm to 100mm symmetrically or asymmetrically between the drums (2.1, 2.2) is adjustable.

11. Device according to one of claims 8 to 10,

characterized in that

the drums (2.1, 2.2) have identical or different drum diameters (D ₁ -D ₂ ) with a diameter ratio in the range from 0.5 to 2.0 in order to form a symmetrical or asymmetrical forming gap (6).

12. Device according to claim 11,

characterized in that

the drums (2.1, 2.2) have a drum diameter in the range of 100 mm to 800 mm.

13. Device according to one of claims 8 to 12,

characterized in that

one of the drums (2.1, 2.2) or both drums (2.1, 2.2) has an inner suction chamber (4, 4 ') which is connected to a vacuum source (5, 5') and through the air-permeable drum wall (3) for Environment shielded.

14. Device according to claim 13,

characterized in that

an angular position of the suction chamber (4, 4 ') on the circumference of the drum (2.1, 2.2) is adjustable.