EP1749918B1 - Method and device for impregnating a fibrous material - Google Patents

Abstract

Fibers are fed to an opening unit (1), e.g. fitted with beater rollers, after which weight and initial moisture is measured (2) to determine the required dosing rate. The fibers are then fed to a working chamber (6) in the form of a drum (7) fitted with rotating arms (9) that convey the fiber from the inlet (3) to the outlet (12). Concentrated treatment solution or emulsion is sprayed in controlled amounts into the chamber by nozzles (15) and mixing heads (13) rotating at high speed, e.g. 1500 to 3000 revolutions per minute, to produce a fog. An independent claim is included for the corresponding plant fitted with nozzles and mixing heads, e.g. as a rotary nozzle, incorporating local fiber opening rotors (14). The circumference of the rotors (14) and the shaft (8) is greater than the fiber length. The working chamber (6) can be followed by a drying plant.

Description

The invention relates to a method and a device for impregnating a fiber material with an impregnating agent containing as a solution or an emulsion at least one additive.

State of the art

Such methods are used to impregnate any fibrous materials, which may be synthetic or natural fibers, with additives which serve to formulate certain performance characteristics of the fibrous material. For example, additives are used to make the fibers of the fiber material flame resistant or to protect against fungal or bacterial attack. It is known to impregnate non-woven structures based on fiber materials, for example mats, which are used as insulation materials by means of spraying or by means of a dip impregnation. When spraying the mats, however, a uniform penetration of the fibers is not guaranteed, since due to the shadow effect of the compacted fibers a homogeneous, all-round impregnation is not possible. In the case of dip impregnation, the mats are flooded with the liquid impregnating agent. Natural fibers especially absorb the liquid. The mats must therefore be subsequently dried consuming to ensure storage stability. This method is therefore uneconomical.

In the document DE 198 29 277 A1 is an impregnation by spraying or dipping described. The spraying is done in a version in a rotary dryer executed. The addition of fibers to be impregnated into a drum-like system leads to the fibers concentrating on the inner wall and becoming entangled with one another. The felting prevents complete impregnation.

In the document DE 43 39 078 C2 describes a method in which the impregnation is carried out by means of a multi-stage immersion process in different baths. This has the disadvantage that contamination of the subsequent baths occurs due entrained material. In addition, subsequent to the multi-stage dipping process again a complex drying of the fiber material is necessary.

In the document US 3,393,537 ( DE 1 635 091 A1 ) describes a machine for treating loose fibers with a liquid.

The invention

The object of the invention is to provide a method and an apparatus for impregnating a fiber material with an impregnating agent, in which a substantially homogeneously distributed impregnation of the fibers is achieved.

This object is achieved by a method according to independent claim 1 and a device according to independent claim 19. Advantageous embodiments of the invention are the subject of dependent claims.

According to one aspect of the invention, there is provided a method of impregnating a fibrous material with an impregnating agent containing as an additive or an emulsion an additive in which the fibrous material to be impregnated is pre-dissolved by means of a pulper; the pre-extruded fiber material is introduced by metering in metered quantities through an inlet in a working space of a continuous mixing system; the introduced fiber material in the working space of the continuous mixing system by means of a conveyor and mixing means past mixing heads and the mixing heads at least partially conveyed from the inlet along a conveying path to an outlet; The guided past the mixing heads and this at least partially surrounding fiber material with the help of the mixing heads in a region around the mixing heads around loosened locally and treated with the impregnating agent by the impregnating agent is introduced by means of the mixing heads via one or more nozzles in the locally loosened fiber material whereby the impregnating agent is distributed substantially homogeneously over the fibers of the fibrous material; and applying the impregnating agent treated fiber material through the outlet from the working space.

According to a further aspect of the invention, there is provided an apparatus for impregnating a fibrous material with an impregnating agent containing as a solution or an emulsion at least one additive, the apparatus having a dissolving means for pre-dissolving the fibrous material, a continuous mixing system for treating the fibrous material to be impregnated the impregnating agent and a metering device upstream of the continuous mixing system for the metered feeding of the continuous mixing system with the previously dissolved fiber material, and wherein in the continuous mixing system, a working space for receiving the introduced via the metering fiber material is formed in the working space a conveying and mixing device is arranged with the introduced fiber material can be conveyed from an inlet of the working space along a conveying path to an outlet of the working space, and mixing heads are arranged in the working space are with which the along the conveyor line on the mixing heads conveyed over fiber material loosened locally and with which the impregnating agent can be introduced via one or more nozzles in the locally loosened fiber material.

The impregnating agent is preferably applied with a pressure for dispensing, so that the impregnating agent is sprayed.

An essential. Advantage, which is achieved with the invention over the prior art, is that a substantially homogeneously distributed impregnation of the fibers is achieved. The impregnating agent is distributed to save material and evenly over the fibers to be impregnated. This is achieved in particular by the fact that the fiber material is dissolved prior to introduction into the working space, which is preferably carried out to the separation of the fiber material, and with the help of the mixing heads a local loosening of the fiber material is performed, so that a felting of the fiber material is avoided , In this way, the introduced impregnating material meets a loosened fiber material, in which hardly any shadow effect of fibers compared to other fibers occurs.

Since the fiber material is conveyed to the mixing heads at least partially surrounding in the working space, the impregnating agent is introduced directly into the loosened fiber material. Losses that occur when impregnating is not introduced into the fiber material, but for example on the inner wall of the working space, are avoided. This also ensures that as little additive as possible must be used to impregnate the fiber material. In this way, the method contributes to cost savings.

The avoidance of the unintentional distribution of impregnating agent on the inner regions of the working space further contributes to the fact that the wear of the system is reduced because less contamination of the components occurs in the working space. Therefore, the cleaning intervals can be extended. The deposition of impregnating agent on such components may also cause damage to these components, for example due to the chemically aggressive effect of the additive.

An expedient embodiment of the invention provides that the impregnating agent as a highly concentrated solution / emulsion of the at least one additive on the one or all nozzles is introduced. In contrast to the prior art, it is possible in the proposed method to introduce highly concentrated solutions / emulsions of the at least one additive. 40 or 50 percent solutions / emulsions can be used. In this way, the proportion of distributed solvent is minimized, whereby the total moisture content of the impregnated fibers can be kept as low as possible.

A homogeneous distribution of the impregnating agent on the fibers to be impregnated is supported in a development of the invention in that the impregnating agent is introduced as a mist, for example as a spray or spray.

A targeted and material-saving use of the additive is achieved in one embodiment of the invention in that an amount of sprayed with the impregnating at least one additive in dependence on a solids content of the metered amounts of introduced in the working space dissolved fiber material is determined. In this case, the procedure is preferably such that the weight of the solid of the fiber material is determined on the basis of a weighing and then the amount of additive is determined which is necessary to achieve a desired impregnation of the fiber material. Such a process design in turn supports an efficient use of the at least one additive.

It is expedient to introduce a flameproofing agent and / or a mildewproofing agent as the at least one additive with the impregnating agent. In principle, any additives can be distributed substantially homogeneously over the fibers to be impregnated with the aid of the method. In one embodiment of the invention can be provided that are introduced along the conveying path via the mixing heads impregnating agent with various additives. In this way, a successively carried out impregnation of the fiber material with different additives is possible. Thus, in a first section of the conveyor line the fiber material can be impregnated, for example, with a flame retardant. In a later section of the conveyor line, a mold protection agent is additionally sprayed in.

The material-saving and efficient use of the at least one additive is supported in one embodiment of the invention in that the mixing heads during the introduction of one or all impregnating continuously surrounded by the funded from the inlet to the outlet of the working space fiber material substantially. This means that the introduction of the impregnating agent takes place continuously into the locally loosened fiber material. It can even be provided to provide a respective sensor device in the region of the mixing heads, which controls the introduction of the impregnating agent such that impregnating agent is introduced only if it is determined by means of the sensor device that the mixing head is surrounded by fiber material to be impregnated. As the sensor device, for example, an optical sensor can be used.

In one embodiment of the invention it can be provided that the fiber material surrounding the mixing heads is locally loosened up with a rotating loosening device formed on the mixing heads in the area around the mixing heads. In this way, the most optimized possible loosening of the fiber material to be impregnated is achieved. The rotary loosening device on the mixing heads is preferably formed by means of a rotating member having a circumferential length which is greater than an elongated length of the longest fibers covered by the fiber material to be impregnated. With the help of such a vote of the rotating component as a function of the longest fibers is prevented that the fibers wrap around the rotating member, which on the one hand would lead to a poorer result of the impregnation and on the other hand can lead to damage to the system.

The local loosening of the fiber material for spraying the impregnating agent is preferably achieved in that the rotating loosening device rotates at high speed at the mixing heads at a speed of about 500 to 3000 revolutions per minute, preferably at a speed of about 1,000 to 3,000 revolutions per minute, more preferably at a speed of about 1,500 to 3,000 revolutions per minute.

In order to promote the fiber material to be impregnated in the working space with a desired throughput and at the same time to obtain a loosened state, an embodiment of the invention provides that the introduced fiber material in the working space along the conveying path conveyed by means of entrainment tools encompassed by the conveying and mixing device mounted on a shaft disposed in the working space and rotated with the shaft to convey the introduced fiber material from the inlet to the outlet.

As a wave is used in a development of the invention, a shaft having a circumferential length which is greater than a stretched length of the longest of the fiber material to be impregnated fibers. This prevents that the fibers of the fiber material to be impregnated wrap around the shaft or there is an increased entanglement of the fiber material.

The method can be used to provide artificial fibers or natural fibers, in particular fibers of renewable raw materials such as annual plants with a substantially homogeneously distributed impregnation. Compared to known methods, the advantages in particular in the impregnation of a long fiber material with fibers having a length of about 30mm to about 200mm unfold.

Embodiments of the invention may provide that prior to introduction of the dissolved fiber material by means of a moisture analysis, a basic moisture of the Fiber material and / or after the application of the treated fiber material by means of a further moisture analysis, a total moisture content of the treated fiber material is determined. Based on the information about the determined ground moisture of the metered fiber material, the amount of solvents can be determined, which is introduced via the mixing heads, so that the treated fiber material then has a predetermined total moisture. Compliance with the predetermined total moisture can be checked with the help of further moisture analysis. In addition, the information about the total moisture of the discharged fiber material can be used to decide on an optional, the impregnation downstream drying of the discharged fiber material. In particular, it can be determined whether and, if appropriate, to what extent post-drying is necessary.

In a preferred embodiment of the invention it is provided that the treated fiber material is applied with a total moisture content of less than about 25% from the working space. This has the advantage that the discharged fiber material can be processed without further drying, for example for producing an insulating material.

The most homogeneous possible distribution of the impregnating agent on the fiber material to be treated is supported in an expedient embodiment of the invention in that the one or all nozzles for discharging the impregnating agent are designed as a rotary nozzle. In particular, the use of rotary nozzles also has the advantage that, after stopping the supply of impregnating agent to the rotary nozzle, residues of the impregnating agent escape from the rotary nozzle due to the centrifugal force in a very short time, so that later dripping out of the nozzle is prevented. Moreover, in this case, it is not necessary to close the nozzle by mechanical means. One or more rotary nozzles may be formed on the mixing heads as separately rotatable nozzles. However, it is particularly preferred that the one or all nozzles of a mixing head in the rotating component are formed, which in turn is part of the loosening device. In this way, an integration of the one or all nozzles in the loosening / rotating component is achieved. In this embodiment, it can be expediently provided that the one or all nozzles are formed as a respective opening on the loosening device, which is supplied via a feed channel with the impregnating agent to be applied. For application, the impregnating agent can be subjected to a pressure. Alternatively or in combination with this, the application of the impregnating agent can also take place as a result of the centrifugal force acting upon rotation of the rotary nozzle.

Preferred embodiments of the invention

Fig. 1

eine schematische Darstellung einer Vorrichtung zum Imprägnieren eines Fasermaterials;

Fig. 2

einen Eingangsabschnitt der Vorrichtung nach Fig. 1 im Detail; und

Fig. 3

eine schematische Darstellung einer Mischtrommel der Vorrichtung nach Fig. 1, die mit zu imprägnierendem Fasermaterial befüllt ist.

The invention is explained below with reference to embodiments with reference to figures of a drawing. Hereby show:

Fig. 1

a schematic representation of an apparatus for impregnating a fiber material;

Fig. 2

an input portion of the device according to Fig. 1 in detail; and

Fig. 3

a schematic representation of a mixing drum of the device according to Fig. 1 , which is filled with fiber material to be impregnated.

Fig. 1 shows a schematic representation of an apparatus for impregnating a fiber material with an impregnating agent containing as a solution or an emulsion one or more additives. The impregnating agent is atomized as a liquid. With the help of impregnation, for example, a flame retardant and / or a mold protection for the impregnated fibers are formed.

Before the fiber material to be impregnated is exposed to the treatment with the liquid impregnating agent, the fiber material is separated by means of a dissolving device 1. The dissolved fiber material is then using a Metering device 2 in metered quantities fed to an inlet 3 of a continuous mixing system 4, preferably continuously.

Fig. 2 shows a schematic representation of the opening device 1 and the metering device 2 in detail. According to Fig. 2 the dissolved fiber material is weighed by means of a balance 2a and fed via a conveyor belt 5 to the inlet 3 in metered quantities.

In order to determine the solids content of the fiber material to be impregnated, the fiber material is subjected to a moisture analysis in dissolved, optionally isolated, or unresolved state, so that a basic moisture of the fiber material to be impregnated is determined. Using the information about the basic moisture and the weight of a metered amount of the fiber material, the solids content of the metered amount can be determined. This information is used to determine an amount of additive which is sprayed after introduction of the metered amount via the inlet 3 for impregnating the introduced amount of fiber material with the liquid impregnating agent. The information about the basic moisture of the introduced fiber material can also be used to determine an amount of solvent of the impregnating agent, which ensures the maintenance of a maximum value for the basic moisture of the treated fiber material for the treated fiber material. Table 1 shows examples of the determination of the additive to be added and / or the solvent to be used, depending on a certain solids content. <u> Table 1 </ u> Fiber addition in the mixer (wet) kg / h 1000 1000 1000 1000 Moisture of the fiber % on atro 10 8th 10 10 free moisture of the fiber kg / h 90.91 74.07 90.91 90.91 Fiber addition amount in the mixer (dry) kg / h 909.09 925.93 909.09 909.09 Solids content of the additive on fiber % on atro 10 10 8th 8th Solids content of the additive on fiber kg / h on atro 90.9 92.59 72.73 72.73 Solution of the additive % 40 40 40 45 Addition amount of additive mixture kg / h 227.25 231.47 181.8 161.62 Addition amount of water kg / h 136.35 138.88 109.1 88.88 Fiber weight plus additive kg / h on atro 999.99 1,018.51 981.81 981.81 Free moisture of the fiber after additive addition kg / h 227.28 212.96 199.99 179.79 Fiber moisture after mixing process % on atro 22.72 20.9 20.36 18.31

According to Fig. 1 enters the introduced through the inlet 3 in metered quantities of fiber material in a working space 6, which is formed in a mixing drum 7. In the mixing drum 7, a shaft 8 is arranged centrally, are mounted on the driving tools 9, which are rotated by means of the shaft 8. With the help of the shaft 8 and the entrainment tools 9, a mixing and conveying device 10 is formed to promote the introduced via the inlet 3 fiber material from the inlet along a conveying path 11 to an outlet 12. The number and contour of the driving tools 9 is matched to the properties of the fiber material to be impregnated. In particular, the type of fiber and the length of the fibers play a role here essential role. By the entrainment tools 9 are arranged offset on the shaft 8, it is ensured that the fibers are conveyed without entanglement along the conveyor line 11 to the outlet 12.
The diameter of the mixing drum 7 and its length are specifically tailored to a desired throughput of fiber material and the properties of the fiber material. In addition, the throughput is influenced by the speed of the shaft 8.

On the inside of the mixing drum 7, a plurality of mixing heads 13 along the conveying path 11 are arranged. The mixing heads 13 each have a rotating component 14 and a nozzle 15, which is integrated into the rotating component 14. The nozzle 15 is formed in the rotating member 14 as an opening with a feed channel behind it, through which the impregnating agent to be applied is supplied. The fibrous material to be impregnated is conveyed past the mixing heads 13 during conveyance along the conveying path 11 and conveyed to the outlet 12. Characterized in that the fiber material to be impregnated on its way along the conveyor section 11 is guided past the mixing heads 13, there is a local loosening of the fiber material around the mixing heads 13, namely with the aid of the respective rotating member 14, which acts as a loosening device. On the rotating member 14 projections are formed, which serve to entrain fibers, whereby the loosening is supported. In the so loosened locally fiber material is sprayed through the nozzle 15, the liquid impregnating directly into the fiber material. Each of the mixing heads 13 may have one or more nozzles.

To optimize the local loosening of the fiber material to be impregnated, the rotating components 14 are rotated at high speed at a speed of about 500 to 3000 revolutions per minute, preferably at a speed of about 1,000 to 3,000 revolutions per minute, more preferably at a speed of about 1,500 to 3,000 revolutions per minute. The desired speed is in Depending on the diameter of the rotating member 14 and the fiber material set. A circumferential length of the rotary member 14 is larger than an elongated fiber length of the longest fibers included in the fiber material to be impregnated, so that the fibers do not wind around the rotary member 14. Similarly, the circumferential length of the shaft 8 is tuned depending on the fiber length to prevent wrapping of the shaft 8 with the fibers.

The above-described coordination between the metered amount of fiber material and the added additive and the solvent used makes it possible to ensure a given total moisture of the treated fibers. Preferably, this total moisture is less than 25%. Optionally, provision may be made for downstream of the outlet 12 a drying device (not shown), in which the treated fibers are dried to further reduce the total moisture content.

Fig. 3 shows a schematic representation of the mixing drum 7 in the filled state. In this way it is ensured that the mixing head 13 is surrounded by the fiber material, so that the liquid impregnating agent is injected directly into the fiber material.

With the aid of the device described, both artificial fibers and natural fibers can be provided with a homogeneously distributed impregnation. Fiber impregnated in this manner can subsequently be further processed for any desired application. The homogeneously impregnated fibers are preferably used for the production of insulating materials, for example in the form of mats.

List of reference signs:

1

opening device

2

metering

2a

Libra

3

Inlet

4

Flow mixing system

5

conveyor belt

6

working space

7

mixing drum

8th

wave

9

Entrainment tools

10

Mixing and conveying device

11

conveyor line

12

outlet

13

mixing heads

14

rotating component

15

jet

Claims (29)

1. A method for impregnating a fibre material with an impregnating agent, which contains at least one additive as a solution or emulsion, in which method:

   - the fibre material to be impregnated is opened up beforehand by means of an opening device (1);

   - the fibre material that has previously been opened up is introduced in metered quantities by a metering device (2) through an inlet (3) into a working chamber (6) of a continuous mixing system (4);

   - the fibre material introduced into the working chamber (6) of the continuous mixing system (4) is conveyed past mixing heads (13) by means of a conveying and mixing device (10) and is conveyed, in a manner at least partially surrounding the mixing heads (13), from the inlet (3) along a conveying path (11) to an outlet (12);

   - the fibre material conveyed past the mixing heads (13) and at least partially surrounding the latter is loosened locally by the mixing heads (13) in a region around the mixing heads (13) and is treated with the impregnating agent in that the impregnating agent is introduced by the mixing heads (13) via one or more nozzles (15) into the locally loosened fibre material, as a result of which the impregnating agent is distributed substantially homogeneously over the fibres of the fibre material; and

   - the fibre material treated with the impregnating agent is discharged from the working chamber (6) through the outlet (12).
2. The method according to claim 1, characterized in that the impregnating agent is introduced via the one or all nozzles (15) as a highly concentrated solution / emulsion of the at least one additive.
3. The method according to claim 1 or 2, characterized in that the impregnating agent is introduced as a mist.
4. The method according to any one of the preceding claims, characterized in that a quantity of the at least one additive introduced with the impregnating agent is determined as a function of a solids content of the metered quantity of opened-up fibre material introduced into the working chamber (6).
5. The method according to any one of the preceding claims, characterized in that a flame retardant is introduced as the at least one additive with the impregnating agent.
6. The method according to any one of the preceding claims, characterized in that an anti-mould agent is introduced as a further additive with the impregnating agent.
7. The method according to any one of the preceding claims, characterized in that impregnating agents containing various additives are introduced via the mixing heads (13) along the conveying path (11).
8. The method according to any one of the preceding claims, characterized in that the mixing heads (13), during the introduction of the one or all impregnating agents, are at least partially surrounded continuously by the fibre material conveyed from the inlet (3) to the outlet (12) of the working chamber (6).
9. The method according to any one of the preceding claims, characterized in that the fibre material which at least partially surrounds the mixing heads (13) is locally loosened in the region around the mixing heads (13) by a rotating loosening device (14) formed on the mixing heads (13).
10. The method according to claim 9, characterized in that, as the rotating loosing device on the mixing heads (13), use is made of a rotating component (14) having a circumferential length which is greater than a stretched length of the longest fibres in the fibre material to be impregnated.
11. The method according to claim 9 or 10, characterized in that the rotating loosening device (14) on the mixing heads (13) rotates at a high speed of approximately 500 to 3000 revolutions per minute, preferably at a speed of approximately 1000 to 3000 revolutions per minute, more preferably at a speed of approximately 1500 to 3000 revolutions per minute.
12. The method according to any one of the preceding claims, characterized in that the introduced fibre material is conveyed in the working chamber (6) along the conveying path (11) by means of carrier tools (9) which form part of the conveying and mixing device (10) and which are attached to a shaft (8) arranged in the working chamber (6) and are rotated with the shaft (8) in order to convey the introduced fibre material from the inlet (3) to the outlet (12).
13. The method according to claim 12, characterized in that, as the shaft (8), use is made of a shaft having a circumferential length which is greater than a stretched length of the longest fibres in the fibre material to be impregnated.
14. The method according to any one of the preceding claims, characterized in that the fibre material is impregnated as a long fibre material composed of fibres having a length of approximately 30 mm to approximately 200 mm.
15. The method according to any one of the preceding claims, characterized in that, before introducing the opened-up fibre material, a basic moisture content of the fibre material is determined by means of a moisture analysis.
16. The method according to any one of the preceding claims, characterized in that, after the treated fibre material has been discharged, a total moisture content of the treated fibre material is determined by means of a further moisture analysis.
17. The method according to any one of the preceding claims, characterized in that the treated fibre material is discharged from the working chamber (6) with a total moisture content of less than approximately 25%.
18. The method according to any one of the preceding claims, characterized in that the treated fibre material is dried after being discharged from the working chamber (6).
19. An apparatus for impregnating a fibre material with an impregnating agent which contains at least one additive as a solution or emulsion, said apparatus comprising:

    - an opening device (1) for opening up the fibre material beforehand;

    - a continuous mixing system (4) for treating the fibre material to be impregnated with the impregnating agent; and

    - a metering device (2), arranged upstream of the continuous mixing system (4), for the metered loading of the continuous mixing system (4) with the fibre material that has previously been opened up;

    wherein

    - a working chamber (6) for receiving the fibre material introduced via the metering device (2) is formed in the continuous mixing system (4);

    - arranged in the working chamber (6) is a conveying and mixing device (10), by means of which the introduced fibre material can be conveyed from an inlet (3) of the working chamber (6) along a conveying path (11) to an outlet (12) of the working chamber (6); and

    - arranged in the working chamber (6) are mixing heads (13), by means of which the fibre material conveyed along the conveying path (11) and past the mixing heads (13) can be locally loosened, and by means of which the impregnating agent can be introduced via one or more nozzles (15) into the locally loosened fibre material.
20. The apparatus according to claim 19, characterized in that the mixing heads (13) are arranged one behind the other along the conveying path (11).
21. The apparatus according to claim 19 or 20, characterized in that the one or all nozzles (15) on the mixing heads (13) are formed as rotary nozzles.
22. The apparatus according to any one of claims 19 to 21, characterized in that a rotating loosening device (14) is formed on each of the mixing heads (13), by means of which the conveyed fibre material can be locally loosened in the region around the mixing heads (13).
23. The apparatus according to claim 22, characterized in that the one or all nozzles (15) are integrated in the rotating loosening device (14).
24. The apparatus according to claim 22 or 23, characterized in that the rotating loosening device is a rotating component (14) having a circumferential length which is greater than a stretched length of the longest fibres in the fibre material to be impregnated.
25. The apparatus according to claim 23 or 24, characterized in that the one or all nozzles (15) are formed by openings in the loosening device or the rotating component.
26. The apparatus according to any one of claims 19 to 25, characterized in that the conveying and mixing device (10) has carrier tools (9) which are attached to a shaft (8) arranged in the working chamber (6) and can be rotated with the shaft (8) in order to convey the introduced fibre material from the inlet (3) to the outlet (12).
27. The apparatus according to claim 26, characterized in that the shaft (8) has a circumferential length which is greater than a stretched length of the longest fibres in the fibre material to be impregnated.
28. The apparatus according to any one of claims 19 to 27, characterized by a drying device, arranged downstream of the working chamber (6), for drying treated fibre material.
29. The apparatus according to any one of claims 19 to 28, characterized in that the working chamber (6) is formed in a mixing drum (7).

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