Title of Invention

METHOD AND DEVICE FOR TREATING A FIBER MASS

Abstract

The invention relates to a method and to a device for treating a fiber mass, for example a nonwoven or a woven. Such fiber masses are guided through a pressing stand for treatment in which they are pressed in at least one pressing zone by means of a press roller, thereby pressing out from the fiber mass a treatment fluid already present in the fiber mass. Once the treatment fluid is pressed out, a second treatment fluid is introduced into the fiber mass. In order to achieve as rapid and homogeneous a distribution of the second treatment fluid in the pressed-out fiber mass as possible, the treatment fluid is introduced in an expansion zone in which the pressure exerted by the press roller decreases in the direction of movement (B) of the fiber mass through the press roll surface, the press roll surface being the surface by which the pressure acts onto the fiber mass.

Full Text

Method and device for treating a fibre mass The invention relates to a method for treating a fibre mass, such as a woven cloth or a nonwoven, where the fibre mass is conveyed through a pressing mill, where the fibre mass is pressed in at least one pressing zone by the pressing surface area of at least one press-roll by means of a pressing power acting on the fibre mass, and the pressed fibre mass is impregnated with a treatment fluid, the fibre mass being passed through an expansion region in the pressing zone where the pressing power is reduced in the passing direction of the fibre mass. The invention further relates to a press-roll arrangement for treating a fibre mass moving relatively to the press-roll arrangement, comprising a press-roll with a pressing surface area by means of which in operation in a pressing zone a pressing power acting on the fibre mass is generated, and with an impregnation means by which in operation a treatment fluid is supplied to the fibre mass, the pressing zone forming an expansion region in operation in which the pressing power is reduced in the moving direction of the fibre mass. The term pressing surface area designates the surface which limits, as an imaginary or actually existing surface area, the pressing zone from the upper or lower side of the fibre mass, i.e. the idealized enveloping surface via which the pressing power acts on the fibre mass. For preparing the fibre masses concerned by the invention, conventionally a polymeric mass is melted or dissolved in a solvent and subsequently drawn over spinning devices to form filament yarns. For preparing the filament yarns, various spinning processes, such as dry spinning and wet spinning methods or a combination of dry and wet spinning methods, are possible. In the process, the filaments are generated in a spinning machine and drawn off from the same by one or more draw-off elements being at the same time formed to filament bundles or tows. Subsequently, the filaments are washed and aftertreated in further processing steps. Before the aftertreatment, for example, in the manufacture of staple fibres, the tow of filament yarns arranged in parallel which is drawn off from the spinning machine is supplied to a cutting device. After exiting the cutting device, in general a nonwoven is formed from the individual staple fibres and deposited on a transport device to be further treated. The staples are generated by staple cutting machines, for example in a dry cut by the machine described in "Ullman Volume 11, Fasern-Herstellungsverfahren", pages 249-289. Viscose fibres are spun in general in aqueous media as cellulosic regenerated fibres. For the staple fibre generation from the continuously spun fibre tow, for example a cutting machine is suitable which essentially consists of a pair of rolls for feeding the spinning tow to the cutting apparatus, the actual cutting apparatus and a staple fibre washing-down device. The cutting apparatus draws the tow fed by the draw-off element by means of a water jet injector to the horizontally rotating cutting knives. The cutting knives maintain their edge retention during the cutting process by a continuous regrinding. Moreover, by the water jet supply, a first dissolution of the staple fibre stacks formed during the cutting process is effected before the suspension of the staple fibre stacks at the aftertreatment machine. Such a machine is for example manufactured by the company Ing. A. Maurer S.A. The aftertreatment of for example viscose fibres can or must be effected by various treatment steps. In the process, in aftertreatment machines for viscose fibres, typically the following treatment steps are carried out while supplying a treatment fluid: deacidification, desulphurization, washing, bleaching and washing, antichlorine treatment, washing with water as well as applying an avivage or a fat coat. These treatment steps are conventionally carried out in a device to which the cut staple fibre, also designated as "flock", comes from the cutting machine via a washing-in device while forming a nonwoven coat distributed as uniformly as possible. The device for treating the fibre mass is conventionally formed as a long aggregate in which the fibre mass distributed to a uniform nonwoven or the fibre mass, respec- lively, is conveyed on a transport means through the individual treatment zones. As a transport means, a belt conveyor, for example with an endless travelling screen or an endless wire-cloth belt, an oscillating conveyor or an eccentric notched conveyor can be used. In the treatment of the fibre mass, care has to be taken that the treatment fluids supplied in the individual treatment steps are quickly and homogenously distributed in the suspended nonwoven. At the same time, it is advantageous to remove the treatment fluid from the previous treatment step as completely as possible from the fibre mass before carrying out a treatment step. For removing a treatment fluid from the fibre mass, conventionally a press-roll arrangement is used which exerts a pressing power on the fibre mass. By means of the pressing power, the treatment fluid is pressed out of the fibre mass. In the subsequent treatment step, the pressed fibre mass is then impregnated with the treatment fluid associated to this treatment step. That is, by means of the press-roll arrangement, two subsequent treatment steps are separated. In the region where the pressing power acts on the fibre mass, i.e. the pressing zone, shortly after the point of the highest pressing power, a region is formed where the pressing power is reduced in the conveying direction of the fibre mass. This region is designated as expansion region. In order to moisten the fibre mass with the treatment fluid, conventionally the fibre mass is passed below spray tubs on a transport device. Directly after the pressing out, the treatment fluid is dripped onto the fibre mass by spray installations positioned thereabove. However, the application of the treatment fluid by dropping only effects a nonuniform impregnation and moistening of the fibre mass just pressed. A special problem arises in the preparation of cellulose fibres or nonwovens of cellulose fibres which are prepared by an NMMO or lyocell process. In the process, a spinning solution containing water, cellulose and tertiary amine oxide is extruded to a filament yarn and drawn. During the drawing, the cellulose filaments are exposed to a high mechanical stress. The filaments and staple fibres prepared according to the NMMO or lyocell process comprise a high crystallinity or orientation of the cellulosic molecules, respectively. Due to these product features caused by the manufacturing process, lyocell fibres tend to be fibrillary. Fibrillation means that due to the high crystallinity and orientation small fibrils split off the circular fibre surface of an individual fibre. The formation of fibrils continues along the fibre axis. In order to reduce the tendency of fibrillation, the fibre can be treated with chemical cross-linkers which bind the fibrillary elements to the fibre main body. In general, an interlacing or cross-linkage process is controlled such that the cellulosic fibre tow is impregnated with a chemical cross-linking agent and the cross-linking reaction is started by vaporization at elevated temperatures. The cross-linking agents have to be homogenously introduced into the fibre mass after the fibre preparation, the temperature of the fibre optionally has to be controlled and washed out of the fibre in subsequent treatment steps. Moreover, the cellulose fibre has to be brightened and dried, as other non-cellulosic fibres as well. In this treatment, it is problematic that the cross-linking agents tend to spontaneous chemical degradation or hydrolysis reactions as the chemicals hydrolise in an aqueous medium or are not stable for a long time, respectively. If the reaction parameters - for example the reaction rate or the reaction temperature - are not exactly observed, degradation or decomposition reactions can also occur. Therefore, the cross-linking agent has to be introduced in closed regions while controlling the reaction course as exactly as possible. Usually, the cross-linking agents require a quick introduction into the cellulose fibre with a subsequent quick control of the temperature as well as subsequently a washing out of the remaining chemicals as fast as possible with a cooling-down at the same time. During the so-called cross-linkage, elevated temperatures as well as alkaline or acid liquids act on the fibre mass. The chemical reaction of the cellulose with the cross-linking agent is effected at elevated pH-values (for example approx. 11-14), resulting in a hydrolysis of the cross-linking agent. The cross-linking agent's tendency of decomposition can be repressed by the temperatures in the cross-linking bath being as low as possible. The low temperatures can be adjusted in or in front of the pressing device. After the thermal fixation of the cross-linking agent, i.e. the reaction of the cross-linking agent with the cellulose chains between approx. 20 and 98°C, the alkali has to be removed from the fibre mass for reducing the strain on the cellulosic fibre. Due to the high fibre density and fibre swelling in cellulosic fibre masses, moreover long dwell times for penetrating the fibre mass are necessary, as only a low geodetic height of the liquid positioned thereabove acts on the nonwoven and the pressure losses of the nonwoven can only be overcome by a long action duration of the fluid. The conventional method and the conventional device, where the pressed fibre mass is only sprayed with a treatment fluid, are not sufficient for a precise control of the process parameters exactly in treatment fluids which chemically react easily or decompose, such as cross-linking agents. In view of the methods and devices conventionally employed for treating fibre masses, it is therefore an object of the invention to improve the method mentioned in the beginning and the device mentioned in the beginning, respectively, in such a way that a distribution of the treatment fluid, the temperature-controlling agent (hot water, hot vapour and optionally other heat transfer media) as well as various washing media in the fibre mass as fast and homogenously as possible and thus also an exact process control are possible. This object is achieved for the inventive method mentioned in the beginning in that the treatment fluid is passed into the fibre mass in the expansion region through the pressing surface area. In the press-roll arrangement mentioned in the beginning, this object is achieved in that the press-roll arrangement comprises openings in the expansion region through which in operation the treatment fluid is passed through the pressing surface area into the fibre mass. This solution is simple and has the advantage that the treatment fluid very quickly and homogenously distributes in the pressed and compressed fibre mass which relaxes in the expansion region. As in the expansion region the pressing power is reduced in the moving direction of the fibre mass, in this region the fibre mass automatically takes in the treatment fluid through the pressing surface area. Thus, a uniform and quick penetration of the pressed fibre mass with the treatment fluid already takes place in the pressing zone. Thereby, the treatment process is easier to control. The solution according to the invention has the further advantage that the overall length of a treatment machine can be essentially reduced. In contrast to the conventional machines, where due to the spraying a penetration of the fibre mass is only possible by means of a long action time and a correspondingly longer conveying distance of the fibre mass through the treatment zone, with the solution according to the invention due to the immediate penetration the next treatment step can directly follow the impregnation of the fibre mass with the treatment fluid. That is, with the solution according to the invention, it is possible to design the pressing mill similarly to a rolling mill where the individual rolls directly follow one another in the direction of rolling. According to a further development of the invention, accordingly in the treatment of the fibre mass several treatment steps can be carried out successively by passing the fibre mass successively through several press-roll arrangements, in one press-roll arrangement each a first treatment fluid being pressed out of the fibre mass in the compression zone and the fibre mass being impregnated with a second treatment fluid in the expansion zone. The fibre mass can be conveyed through the pressing zone by means of a separate conveying means, for example in the form of a conveyor belt, the press-roll passively rotating along. However, the press-roll can also be provided with an own driving means. In this case, one can dispense with a separate conveying means, as the press-roll itself forms the conveying means. The peripheral speeds of the press-rolls can be between 0.1 and 400 m/min, preferably between 0.1 and 60 m/minT in particular between 0.1 and 10 m/min. With these peripheral speeds, in a treatment zone a fibre throughput of 10 to 1500 kg/(m2h), preferably between 10 and 1200 kg/(m2h), can be achieved. The fibre throughput is calculated from the weight of the fibre mass in an absolutly dry condition divided by the dwell time per treatment field and is independent of the length of the treatment field. In front of the expansion region, the fibre mass can be passed in the pressing zone through a compression region where the pressing power is increased in the conveying direction of the fibre mass, so that a treatment fluid already present in the fibre mass is pressed out. In a further advantageous embodiment, in the compression region the pressed out treatment fluid can be let off from the fibre mass through the pressing surface area. For doing so, for example a suction means can be provided through which in operation the treatment fluid is sucked off from the compression region. Instead of a suction means, however, only openings in the pressing surface area can be provided through which the treatment fluid automatically passes due to the pressing power increasing in the treatment direction in the compression region, so that after the passage of the fibre mass through the pressing zone almost no more treatment fluid from the previous treatment step is contained in the fibre mass. The line pressure with which a press-roll according to the invention is pressed into the fibre mass is up to 100 N per mm of the roll width. As a supplement or alternatively to the letting off or sucking off of the treatment fluid in the compression zone, a treatment fluid can also be passed in the compression zone through the pressing surface area into the fibre mass for rinsing the fibre mass before pressing it. For example, the fibre mass can be rinsed with the treatment fluid supplied to the upstream press-roll in the expansion zone, so that no treatment fluid from the treatment step which is arranged by the device in front of the compression zone in the transport or conveying direction of the fibre mass, can be carried into the treatment step which is arranged behind the expansion zone in the conveying direction. A thorough and uniform impregnation of the fibre mass with the treatment fluid can be achieved if according to a further advantageous embodiment the treatment fluid is pressed into the fibre mass under pressure, for example by nozzles arranged in the pressing region in the compression and/or expansion region. The liquid throughput referring to the press-roll width can be between 0.1 and 125 m3/(h m), preferably between 0.1 and 50 m3/(h m), in particular between 0.1 and 20 m3/(h m). A particularly compact construction can be achieved if the impregnation means through which the treatment fluid is supplied to the fibre mass is arranged at least by sections within the press-roll. In this case, according to a further embodiment of the invention, the treatment fluid can be conveyed from the inside of the press-roll through openings into the fibre mass. For doing so, the press-roll can be provided with openings at its surface facing the fibre mass through which openings the treatment fluid is conveyed into the fibre mass. The openings can be formed in the surface of the press-roll regularly or irregularly and for example comprise a cross-section which is essentially nozzle-like. The opening degree of the roll, i.e. the relation of the surfaces occupied by the openings to the overall surface of the roll, can be between 1 and 95%, preferably between 3 and 90%, particularly preferred between 3 and 85%. According to another embodiment, the press-roll can, however, form ribs at its surface facing the fibre mass, which form at least by sections the pressing surface area and between which in operation the treatment fluid can be introduced into the fibre mass. According to further embodiments, these ribs can extend essentially transverse to or essentially in the moving direction of the fibre mass. In order to avoid a carrying away or mixing of the treatment fluids from the two treatment steps separated by the press-roll arrangement, according to a further advantageous embodiment, the ribs can be designed as a weir which acts against a flow of the treatment fluid through the press-roll from the compression region to the expansion zone and thus acts against a carrying away of the treatment fluid. This is in particular possible if the ribs extend transversely to the moving direction of the fibre mass. To this end, the height of the ribs can be dimensioned such that in the pressing zone an upper end of a rib facing away from the fibre mass projects essentially between the compression region and the expansion region always above the level of the treatment fluid in the compression region and/or expansion region. In particular in the embodiment of the press-roll with ribs being spaced apart and preferably extending transversely to the conveying direction of the fibre mass, spray nozzles can be integrated inside the press-roll according to a further advantageous embodiment, through which the treatment fluid is directed in operation onto the fibre mass preferably in the pressing zone in a spray or jet form. In order to avoid a conveyance of the treatment fluid out of the compression region through the rotating press-roll into the expansion region, the nozzles can also be directed to the compression region in order to dilute or displace the treatment fluid present therein. A complete moistening of the fibre mass by the treatment fluid delivered by the spray nozzles is achieved if the atomizing cone of the nozzles essentially overlaps in the region of the fibre mass or in the pressing zone, respectively. Depending on the type of the treatment fluid used, the size and weight of the fibre mass as well as the composition of the fibre mass, it can be necessary to regulate the region via which the treatment fluid is conducted through the pressing surface area onto the fibre mass. For doing so, the impregnation means can comprise a regulation means by which the size and the orientation of the exiting region of the treatment fluid in the pressing surface area is regulated. To this end, according to a further advantageous embodiment, the regulation means can be designed as a cover body arranged in the press-roll with a slot arranged in the press-roll, which covers that part of the pressing surface area or the press-roll through which no treatment fluid is to pass. This cover body can for example be designed as a tubular body provided with a longitudinal slot and rotatably held in the press-roll. Instead of or in addition to a supply line of the treatment fluid from the inside of the press-roll, the impregnation means can comprise a supply line through which in operation the treatment fluid is conveyed from outside the press-roll essentially into the expansion region. This supply line can be arranged according to a further advanta- geous embodiment at least in the pressing zone at least by sections between two ribs essentially extending in the moving direction of the fibre mass. In this case, it is advantageous if the section of the supply line facing the pressing surface area essentially flushes with the ribs, so that the pressing surface area is as smooth as possible and offers only little frictional resistance with respect to the fibre mass. Finally, the invention also relates to a pressing mill for treating fibre masses with at least one press-roll arrangement for pressing the fibre masses and with a conveying means for conveying the fibre masses through the pressing mill, a press-roll arrangement according to one of the above described embodiments being used. In a pressing mill with several press-roil arrangements successively arranged in the conveying direction of the fibre mass, the press-roll can directly follow one another. The pressing mill and the press-roll arrangement can be operated with a fibre mass of which the absolutely dry weight per surface unit is between 0.1 to 20 kg/m2, preferably 0.1 to 10 kg/m2. As fibre masses, tows or heavy, thick nonwovens can be af-tertreated. As treatment fluids, pure water, aqueous organic or inorganic solvents, aqueous or concentrated alkaline solutions or acids, bleaching chemicals, preparation means or inert gases, respectively, vapour-like media, heating or cooling media as well as solvent vapours can be used. Opposite the press-roll, a further press-roll can be arranged in the pressing mill in the region of the pressing zone which serves as counterpressure means for taking up the pressing power. This second press-roll can have the same design as the above described first press-roll. In this configuration, the fibre mass is passed between the two press-rolls. As materials for the press-rolls, metals or plastics can be used the surface of which can be rubberized, polished or ground. In order to avoid a damage of the fibres, the edges of the press-rolls and optionally the edges of the openings and ribs arranged at the press-rolls should be broken. In the following, the invention is further illustrated as to its construction and function with reference to embodiments. In the drawings: Fig. 1 shows a schematic representation of a plant for manufacturing a fibre mass; Fig. 2 shows a cross-section of a first embodiment of a press-roll arrangement according to the invention; Fig. 3 shows a cross-section of a further development of the embodiment of Fig. 2; Fig. 4 shows a perspective view of a second embodiment of a press-roll arrangement according to the invention; Fig. 5 shows a cross-section of the embodiment of Fig. 4; Fig. 6 shows a perspective view of a third embodiment of the press-roll arrangement according to the invention; Fig. 7 shows a front view of the embodiment of Fig. 6; Fig. 8 shows a cross-section of a fourth embodiment of a press-roll arrangement according to the invention. First, the course of the method for manufacturing the fibre mass is described with reference to Fig. 1. In a system 1 only schematically represented in Fig. 1, an extrusion solution 2 is prepared. To this end, in one or more mixers a suspension of dry or wet crushed cellu- lose and water and/or tertiary amine oxide is formed. Employing elevated temperatures at low pressure, water is volatilised from the suspension to such an extent that a cellulose solution serving as an extrusion solution is formed. In a reaction vessel 1, an extrusion solution 2 is prepared. The extrusion solution contains cellulose, water and tertiary amine oxide, such as N-methylmorpholine-N-oxide (NMMO), as well as optionally stabilisators for thermally stabilizing the cellulose and the solvent. Examples of stabilisators are: propyl gallate or media having alkaline effects or mixtures thereof. Optionally, further additives can be contained, such as titane dioxide, barium sulphate, graphite, carboxymethylceiluloses, polyethylene glycols, ketine, ketusane, alginic acid, polysaccharides, colorants, antibacterially acting chemicals, flame protection agents containing phosphor, halides or nitrogen, active carbon, carbon blacks or electroconductive carbon blacks, silicic acid as well as organic solvents as diluting agents, etc. The extrusion solution 2 is delivered through a line or conduit system 4 via a pump 3. In the line system 4? a pressure compensation vessel 5 is arranged, which compensates pressure and/or volume flow fluctuations in the line system 4, so that an extrusion head 6 can be continually and uniformly provided with the extrusion solution 2. The line system 4 is provided with means to control the temperature (not shown) by which the temperature of the extrusion solution 2 taken as an example herein can be precisely controlled, as well as with a filtration unit (not shown). This is necessary, as the chemical and mechanical characteristics of the extrusion solution greatly depend on the temperature. Thus, the viscosity of the extrusion solution 2 is reduced as the temperature and/or the shearing rate are increased. In the line system 4, furthermore bursting protection means are provided, which are necessary due to the tendency of the extrusion solution towards a spontaneous exothermic reaction. Due to the bursting protection means, in case of a spontaneous exothermic reaction, damages of the line system 4 and the pressure compensation vessel 5 as well as the downstream extrusion head 6, as they can occur due to the reaction pressure, are avoided. A spontaneous exothermic reaction in the extrusion solution 2, for example, occurs when a certain temperature is exceeded or in case of an ageing of the extrusion solution 2, particularly in dead water zones. In order to avoid the occurrence of dead water zones and burblings and to ensure a uniform flow of the extrusion solution through the line system 4, the line system 4 is formed so as to enhance flows in the overall region through which the highly viscous extrusion solution flows. In the extrusion head 6, the extrusion solution is distributed to a plurality of extrusion ducts 8 in the form of spinning capillaries in a nozzle space 7. The spinning capillaries 8 are arranged in line, in Fig. 1 perpendicularly to the plane of projection. By means of a single extrusion head 6, thus a plurality of continuous moulded products is prepared simultaneously. Moreover, a plurality of extrusion heads 6, each forming a plurality of continuous moulded products or, in case of the embodiment of Fig. 1, filaments, can also be provided. In Fig. 1, only one spinning capillary 8 is shown for the sake of simplicity. Normally, the spinning capillary has an internal diameter D of less than 500 ^m, for special applications, the diameter can also be less than 100 [am, preferably about 50 to 70 (am. The length L of the spinning capillary through which the extrusion solution flows, is at least twice the internal diameter D, maximally 100 to 150 times the internal diameter D. The spinning capillary 8 is at least sectionwise surrounded by a heating means 9 by which the wall temperature of the spinning capillary 8 can be controlled. The wall temperature of the spinning capillary 8 is in operation about 150°C. The temperature of the spinning solution is in operation between about 80 and 130°C. The spinning capillaries 8 can also be disposed in an arbitrary form in a carrier body, the temperature of which is controlled from the outside, so that the hole densities in the extrusion head 6 are high. The heating means 9 preferably extends to the outlet 10 of the extrusion duct situated in the flow direction S. Thereby, the wall of the extrusion duct 8 is heated down to the extrusion duct opening 10. Due to the direct or indirect heating of the extrusion duct, at the internal wall thereof and due to the viscosity of the extrusion solution depending on the temperature, a heated film flow having a low viscosity as compared with the central flow is formed. Thereby, the velocity profile of the extrusion solution within the extrusion duct 8 and the extrusion process are positively changed such that an improved loop stability and a reduced fibrillation tendency of the extruded spinning solution are achieved. In the extrusion duct 8, the extrusion solution is extruded and subsequently exits in the form of a filament 11 in an air gap 12. In the flow direction S of the extrusion solution, the air gap has a height H. In the air gap 12, air 13 is supplied at a high velocity to the extrusion solution from the extrusion head 6. The flow direction can be guided horizontally up to the extrusion filament; the flow velocity of the air 13 can be higher than the extrusion velocity of the filament at which the continuous moulded product exits the extrusion duct opening 10. Due to an air flow which is essentially guided coaxially, a tensile stress acts at the boundary surface between the continuous moulded product 11 and the air 13, which stress can draw the continuous moulded product 11. After having passed the air gap 12, the continuous moulded product enters a coagulation bath zone 14 where it is wetted or moistened with a coagulation solution. The wetting can either be effected by means of a spraying or moistening device (not shown) or by immersing the continuous moulded product 11 in the coagulation bath. Due to the coagulation bath solution, the extrusion solution is stabilized. A further possibility is to deposit the continuous moulded product 11 essentially without tensile stresses downstream of the coagulation bath zone 14 on a conveyor means 15. The conveyor means 15 is equipped as a vibrating conveyor. Due to the to-and-fro movement of the vibrating conveyor 16, the continuous filaments are deposited on the conveyor means in straightened staples 17. Due to the conveyance on the conveyor means 15 without tensile stresses, the continuous moulded product 11 can stabilize without detrimental effects acting on the mechanical characteristics of the continuous moulded product 11, as they can, for example, occur by a premature mechanical load shortly after the extrusion of the continuous moulded product 11. Depending on the design, the continuous moulded product 11 is drawn off by means of a draw-off work 18 upstream or downstream of the conveyor means 15 and supplied to a cutting machine 20 via deflection or conveyor means 19. Via the draw-off work 18, the corresponding fibre parameters, such as titer, stability and stretching, are regulated. The continuous moulded products 11 only of a part of the extrusion heads 6 or of all extrusion heads 6 are introduced into the cutting machine 20 in parallel. In the cutting machine 20, there is positioned a pair of rolls (not shown) for supplying the continuous moulded product bundles 11 of the various extrusion heads 6 to the cutting apparatus, the actual cutting apparatus (not shown) and a staple fibre washing-down device. The cutting apparatus (not shown) draws the tow fed by the pair of draw-off rolls by means of a water jet injector to horizontally rotating cutting knives. By means of the cutting knives, the fibre mass is cut to a predetermined length. The cutting knives maintain their edge retention during the cutting process by a continuous regrinding. By the water jet supply, a first dissolution of the staple fibre stacks formed during the cutting process is effected before the suspension of the staple fibre stacks to form a fibre mass. An essentially mat-like fibre mass 21 exits from the cutting machine 21, which mass, together with the water supplied during the cutting operation, is washed into a device 22 for treating the fibre mass 21. The fibre mass 21 is formed by a random orientation of the fibres cut in the cutting machine 20. The device 22 for treating the fibre mass 21 essentially constitutes the subject matter of the present invention. In the device 22, treatment steps typical of viscose fibres are accomplished, such as deacidification, desulphurization, washing, bleaching and washing, antichlorine treatment, washing with water as well as applying an avivage/fat coating or other chemicals. The individual treatment steps or phases, respectively, each take place in treatment zones 23, 24, 25, 26, 27, which are separated from one another by press-roll arrangements 28, 29, 30, 31, 32, 33. In each treatment zone 23 to 27, via an impregnation means 34, 35, 36, 37, 38 a treatment fluid each associated to this treatment zone or treatment step, respectively, is fed from corresponding reservoirs 39, 40, 41, 42, 43. The treatment zones have a distance of at least about 0.5 m from roll center to roll center in the conveying direction of the fibre masses, however, the distance can be up to 10 m and more depending on the requirement of the treatment operation. In an extreme case, the individual press-roll arrangements 28, 29, 30, 31, 32, 33 can, however, also directly follow one another, so that the press-rolls just do not contact. In the process, the reservoirs 39 to 43 are provided with treatment fluid in a reverse flow, i.e. the treatment fluid from a consecutive step in the conveying direction B of the fibre mass 21 is fed to an upstream treatment step in the treatment direction essentially without being cleaned; the direction of the flow of the treatment fluid through the device 22 is opposite to the conveying direction of the fibre mass 21 through the device 22. In the conveying direction B, consequently the purity of the treatment fluid in the reservoirs 39 to 43, which are disposed as collecting vessel below the fibre mass 21, is increased. The fibre mass 21 is conveyed by the device 22 on a conveyor means 44 which can be designed as endless travelling screen or an endless wire-cloth belt, an oscillating conveyor or an eccentric notched conveyor. The press-roll arrangements 28 to 33 can be designed either, as shown in Fig. 1, as paired rolls or as individual rolls with a fixed counterpressure face. The force of the pressure of the rolls can be generated electrically, hydraulically or pneumatically as well as mechanically, for example by means of leverages. The typical force of pressure of the press-roll is up to approximately 100 N per mm of the roll width. Due to the pressing power exerted by the press-roll arrangements 28 to 33, the treatment fluid introduced into the respective treatment zone 23 to 27 is pressed out of the fibre mass and the treatment fluid is prevented from being carried away from a previous treatment step to the next treatment step. After having passed the device 22, the fibre mass 21 can be fed to further treatment steps not shown in Fig. 1. For example, a drying device with opening aggregates for dehumidifying and relaxing the fibre mass and consecutively a packaging aggregate for manufacturing a product ready for shipping can follow. Fig. 1 shows an example of the preparation of a fibre mass from a spinning solution containing cellulose. However, the use of the device 22 is not restricted to cellulose fibres but can be also used for nonwoven-like or woven fibre masses of filaments of other compositions. For preparing such fibre masses of non-viscous or non-cellulosic fibres, other manufacturing methods are known from the prior art. In the following, one press-roll arrangement each is described by way of example. As the basic function of the press-roll arrangements 28 to 33 is the same in each case, in the following description only one single press-roll arrangement is discussed by way of example. i Fig. 2 shows a first embodiment of a press-roll arrangement 50 according to the invention for treating the fibre mass 21 in a section perpendicular to the moving direction B of the fibre mass 21. The press-roll arrangement shown in Fig. 2 is used for washing the tow or the staple ) fibres with low speeds and large fibre masses, the fibre mass being moved at a speed of approximately 40 m/min in the conveying direction. This speed corresponds to the extrusion rate of the continuous moulded products at the extrusion head. With a basis weight of the fibre mass of 0.1 kg/m2 when absolutely dry, the fibre through- put is approx. 52 kg/(m2h), the treatment fluid being fed at a flow rate of 125 rrr7(h m) per m of the roll width. The press-roll arrangement 50 comprises a press-roll 51 which is rotatably mounted in a bearing not shown in Fig. 2 and rotates along with the motion of the fibre mass 21 in the direction of the arrow P. The press-roll 51 is pressed into the fibre mass 21 with a force of pressure F. In the process, a pressing surface area 52 which is the idealized enveloping surface about the press-roll 51 by which the pressing power generated by the force of pressure F acts on the fibre mass 21, is formed. The region across which the force of pressure F acts as pressing power on the fibre mass 21 via the pressing surface area 52 is designated as pressing zone 53. in the moving direction B of the fibre mass 21, in the pressing zone first of all the pressing power is increased up to approximatley the region where the press-roll 51 maximally penetrates the fibre mass 21. The region of the pressing power increasing in the moving direction B of the fibre mass is hereinafter referred to as compression region 54. Following the compression region 54 in the moving direction B of the fibre mass 21 is an expansion region 55 where the pressing power is again reduced in the moving direction B of the fibre mass. In the compression zone 54, due to the increased pressing power the treatment fluid 56 taken up in the fibre mass 21 is pressed out, so that following the compression zone 54 nearly no more treatment fluid 56 from the previous treatment step is present in the fibre mass 21. In the embodiment of Fig. 2, the press-roll 51 is provided with passages 57 which extend from the inside of the press-roll to the outside of the press-roll. At the outer peripheral surface 59 of the press-roll 51, the passages 57 end in recesses 58, the diameter of which is larger than the diameter of the passages 57. The passages can also be attached slit-like along the press-roll axis and be correspondingly distributed across the periphery. The diameter of the bores is 3 to 12 mm with a roll diameter of 400 mm. The opening degree of the press-roli 51 is approximately 5 to 40%, largely independent of its diameter. The through bores 57 can be distributed arbitrarily, in rows in the axial direction or in the peripheral direction or set off relative to one another at the outer peripheral surface 59. In the embodiment of Fig. 2, the inside of the press-roll forms a part of the impregnation means through which treatment fluid is introduced into the fibre mass. Inside the press-roll 51, a cover body 60 is provided, which has an essentially tubular design and comprises an opening 61 extending in the axial direction of the press-roll 51 in the form of a slit facing the pressing zone. The cover body 60 does not move along with the press-roll 51 but is stationary. At each of its ends facing the slit, the cover body 60 is provided with sealing elements 62, so that no treatment fluid from the interior space 63 of the press-roll 51 can come between the cover body 60 and the internal peripheral surface 64 of the press-roll 51. The cover body 60 serves for defining the region 65 via which treatment fluid is introduced into the fibre mass 21. The region 65 extends according to Fig. 2 mainly into the region of the expansion zone 55, but also - at least by sections - into the region of the compression zone 54. If treatment fluid, which can be, for example, under a pressure of 2.5 to 3 bar, is conducted from the interior space 63 of the press-roll 51 through the passages 57, this treatment fluid will wash out the treatment fluid 56 from the previous treatment step in the compression zone 54, as schematically indicated . in Fig. 2, and at the same time it will be absorbed in the expansion zone 55 by the capillary action and the swelling of the fibre mass 21 due to the reducing pressure. As a result, a homogenous and fast distribution of the treatment fluid supplied through the press-roll 51 or the pressing surface area 52, respectively, is achieved. In ) order to be able to adjust the position of the slit 61 relatively to the pressing zone 53, the first cover body 60 is coaxially held in the press-roll 51 to be pivoted about its longitudinal axis X, as implied by the double arrow A. Fig. 3 shows a further development of the embodiment of Fig. 2. Here, below only the differences to the embodiment of Fig. 2 are discussed. The press-roll arrangement of Fig. 3 can, for example, be used for washing a cellulose nonwoven as fibre mass 21 having a weight of approximately 4.1 kg/m2. In this application, the fibre mass is moved in the conveying direction at a rate of approx. 0.1 m/min. The fibre throughput per m of the roll width is about 40 kg/(h m2) with such an application. The treatment fluid is supplied with a throughput of 0.7 m3/(h m). In contrast to the one-piece cover body 60 of Fig. 2, the cover body is divided into two cover bodies 60a and 60b in the further development of Fig. 3. Each of the two cover bodies 60a, 60b is held independently of the other cover body at the inner peripheral surface 64 of the press-roll 51 to be pivoted about the longitudinal axis thereof. Thus, in the press-roll arrangement 50 according to Fig. 3, the opening angle a as well as the orientation of the slit 61 can be changed by adjusting one of the cover bodies 60a, 60b or both cover bodies 60a, 60b. In order to seal the interior space 63 of the press-roll 51 outside the slit region, a sealing body 66 is provided which covers a moving slit 67 which is also formed by the two cover bodies 60a, 60b and ensures the movability of the two cover bodies 60a, 60b relative to one another. The sealing body 66 can be arranged within the cover bodies 60a, 60b or, in an alternative embodiment, between the cover body 60a, 60b and the press-roll 51. At its ends, the tubular sealing body 66 provided with a longitudinal slit is provided with sealing elements 68 which avoid the penetration of treatment fluid between the cover body and the sealing body. In the embodiment of Fig. 3, due to the high variability with respect to the size and position of the treatment zone 65, an exact adaptation to the respective treatment step and the moistening requirements of the treatment fluid fed into this treatment step can be effected. In phantom lines, for example a one-sided adjustment of the left cover body 60b is shown in Fig. 3, resulting in a treatment zone 65 being only situated in the expansion region 55, through which the treatment fluid is introduced into the fibre mass 21. A second embodiment of a press-roll arrangement according to the invention is represented in Fig. 4. Here, for elements the design or function of which essentially correspond to the elements of the previous embodiment, the same reference numerals are used. In the embodiment of Fig. 4, the press-roll 51 is formed of a plurality of ribs 70 extending in the axial direction X of the press-roll 51. The ribs have a wall thickness which increases in the radial direction from the inside of the press-roll 51 to the outside. At their outer side, the ribs 70 at least by sections form the pressing surface area 52 in the pressing zone 53. The ribs 70 are each fixed at mounting plates or rings at the two ends of the pressing surface area positioned in the axial direction X. The ribs 70 all extend in parallel to one another and are equally spaced apart from one another, the region 71 between them is essentially free of materials. The ribs 70 can be interconnected by plate- or ring-like struts extending in the peripheral direction, so that they obtain a higher mechanical stability. In the embodiment represented in Fig. 4, the opening degree of the press-roll 40 can be in individual cases up to between 90 and 95%. The number of ribs is between 30 and 80, preferably about 60. With a diameter of the press-roll of 400 mm, the width of the rib can be between 1 and 20 mm in the peripheral direction, using broader struts leads to a higher pressure, but a lower flow rate. In the interior space 63 of the press-roll 51, an impregnation device 72 is arranged, through which treatment fluid is guided into the interior space 63 of the press-roll 51. Such an impregnation means 72 can for example alternatively also be used in the embodiment of Fig. 2 instead of or together with the cover body 60. Inversely, the impregnation means can also be used according to the embodiment of Fig. 2 or 3 together with the cover body 60 described therein. The impregnation means 72 of the embodiment of Fig. 4 consists of a central supply line 73 extending coaxially to the axis X of the press-roll 51. The supply line 73 is represented in Fig. 4 cut at its end positioned in the axial direction X, however, at its right end in Fig. 4, an end cap can be provided, or the supply line 73 can extend through all of the press-roll 51 in the axial direction X and supply the treatment fluid to a further press-roll arrangement. The end of the supply line 73 in the flow direction S of the treatment fluid can be connected with the inlet of the supply line 73 in order to make possible a recycling of the treatment fluid in this treatment step. The impregnation means 72 is further provided with one or a plurality of spray nozzles 74 which are directed to the fibre mass 21. The treatment fluid flows from the central supply line or the collective tube 73 through the individual nozzles 74 and between the ribs 70 into the fibre mass 21. Fig. 5 shows a section perpendicular to the axial direction X of the embodiment of Fig. 4. In Fig. 5, one can see that the treatment fluid from each of the spray nozzles 74 forms an atomizing cone 75, the atomizing cones 75 overlapping such that in the pressing zone 53 there is no region which is not moistened by the treatment fluid. The atomizing cones 75 can be conical or even. In order to prevent the treatment fluid 56 from being carried away into the region situated downstream of the pressing zone 53 in the moving direction B of the fibre mass 21, the height H of each rib 70 is dimensioned such that the ribs essentially situated in the pressing zone 53 form a weir through which a direct flow of the treatment fluid between the regions at both sides of the pressing zone is not possible. As by the rotation D of the press-roll 51 treatment fluid could be conveyed from one treatment step to the next treatment step through the space 71 between two ribs 70, a spraying nozzle 74' is directed to the compression zone in order to wash out treat- merit fluid 56 possibly flowing in from the previous treatment step. Via a regulation means 76, for example by the spraying nozzles 74 being attached to tubes 76 rotatable relative to one another and being concentric to the supply line 73, the treatment region 65 can be regulated with respect to size and orientation by adjusting the spray nozzles 74. The distance between the ribs in the peripheral direction is dimensioned such that a sufficient amount of treatment fluid can pass between the ribs and at the same time the pressing power in the pressing zone 53 can still uniformly act on the fibre mass 21. Fig. 6 shows a perspective view of a third embodiment of a press-roll arrangement 50 according to the invention. Here, for elements the design and function of which correspond to an element of the previous embodiments, the same reference numerals are used as in the previous embodiments. The press-roll 51 of the embodiment of Fig. 6 comprises ribs 70 spaced apart in the axial direction X of the press-roll 51 between which a space 71 is formed. The press-roll arrangement 50 further comprises two impregnation means 72a, 72b, which are arranged at both sides of the press-roll 51 with respect to the moving direction B of the fibre mass not shown in Fig. 6 for the sake of simplicity. Each impregnation means 72a, 72b comprises a collective tube 73 extending in parallel to the axial direction X of the press-roll 51 from which supply lines 80 extend into the spaces 71 between the ribs 70 down into the pressing zone 53. In the embodiment of Fig. 6, the supply lines 80 of the two impregnation means 72a and 72b are interconnected in one piece, so that the treatment fluid from the collective tube 73 of the impregnation means 72a flows to the collective tube 73 of the impregnation means 72b and a part of the treatment fluid exits in the pressing zone 53 through openings of the supply lines 80 not shown in Fig. 6. Alternatively, the supply lines 80 of the impregnation means 72a and the supply lines 80 of the impregnations means 72b can be separated, so that through the impregnation means 72a another treatment fluid than through the treatment means 72b is introduced into the pressing zone 53. This enables a higher variability and adaptability of the treatment to be carried out by the press-roll arrangement 50 with various fibre masses and treatment fluids. The cross-section of the supply lines 80 is designed such that it essentially corresponds to the cross-section of the spaces 71 and thus largely fills the spaces 71. The flow S of the treatment fluid through the collective tube 73 is conducted through the supply lines 80 into the pressing zone 53. This can be in particular seen in Fig. 7, where a front view of the embodiment of Fig. 6 is shown in the moving direction B of the fibre mass 21. In Fig. 7, a supply line is shown as partial section in the region of the pressing zone, in particular in the region of the expansion region 55. The supply line comprises openings 81 in this region, through which the treatment fluid exits into the space 71 and enters the fibre mass 21 through the pressing surface area 52. Alternatively to the representation in Fig. 7, the section of the supply lines 80 facing the fibre mass 21 can also come into contact with the fibre mass 21. In this case, however, special arrangements with respect to the surface quality and the abrasion resistance of the supply lines 80 have to be taken in order to avoid a damage of the fibre mass 21 and a premature wear of the supply lines 80 by the fibre mass 21 being passed under pressure. In an alternative design of the embodiment of Figs. 6 and 7, the impregnation means 72a being in front with respect to the moving direction B of the fibre mass 21 can also be designed as a suction means by which treatment fluid is sucked off for example from the compression region via the openings 81 in the supply lines 80. In Fig. 7, furthermore a driving means 82, for example an electric motor, is represented, by which the press-roll 51 is rotatably driven synchronously with the motion of the fibre mass. Such a driving means 82 can also be used with other embodiments. In this design, the press-roll itself can be employed as conveyor means for the fibre mass 21, by which the fibre mass 21 is transported through the individual treatment steps of the pressing mill. Fig. 8 shows a fourth embodiment of a press-roll arrangement 50 according to the invention in a section in parallel to the moving direction B of the fibre mass 21 and perpendicular to the axial direction X of the press-roll 51. The press-roll arrangement 50 according to Fig. 8 comprises a counterpressure roll 90 which is pressed into the fibre mass 21 with a force of pressure F2 opposite to the press-roll's 51 force of pressure Fi having the same value. The press-roll 51 and the counterpressure roll 90 both comprise the same configuration which corresponds to the configuration of the first embodiment as represented in Figs. 2 and 3. For the sake of simplicity, for the embodiment of Fig. 8 therefore for elements, the construction and function of which correspond to previous embodiments, the same reference numerals are used. In the embodiment of Fig. 8, in the expansion region 54 the treatment fluid is sucked Off from the previous treatment step by the counterpressure roll 90, as schematically Shown by the arrow Si, while in the expansion region 55 treatment fluid for the next treatment step is conducted through the press-roll 52 into the fibre mass, as indicated by the arrow $2. Alternatively to this embodiment, each roll 51, 90 can effect a removal by suction as well as an impregnation in the pressing zone 53. As represented in Fig. 1 by means of the device 22, when using the press-roll arrangement 50 according to the invention in a pressing mill 22, the press-roll arrangement for the next treatment step can directly follow, as due to the impregnation of the fibre mass 21 through the pressing surface area 52, an immediate homogenous distribution of the treatment fluid in the fibre mass 21 is effected. Thereby, the overall length of the pressing and treatment device 22 is considerably reduced. Due to the immediate homogenous distribution within the fibre mass 21, which is supported by the short fibre distance in the expansion zone 55 and the resulting capillary effect, the impregnation process can be accomplished more precisely and be controlled more easily. As a result, even an impregnation with treatment fluids to be handled carefully, which possibly tend to react chemically, is possible. The rolls according to the invention can also be employed at other locations of a plant for manufacturing fibres, for example as draw-off rolls with integrated waxing means. Apart from the fibre mass of cellulose described by way of example, fibre masses of natural or synthetic fibres can also be treated by the device according to the invention and the method according to the invention, for example fibre masses of viscose, acetate, polyester, polyamide and polyacryl. Below, special examples for further illustrating the above-mentioned embodiments are given in a table. In the examples 1 to 4 of the following table, a fibre tow manufactured according to the Lyocell-method is brought into a staple shape by means of a wet cutting machine and in this condition applied on a treatment device 22 as fibre mass 21. Concerning the indications of weight, the fibre mass in an absolutely dry condition is taken as a basis. In example 5, the fibre tow is supplied to the treatment device 22 as fibre mass 21 directly without cutting it beforehand. As treatment fluid, water is used in all examples. The device 22 is in all examples 1 to 5 designed such that in every treatment zone the fibre mass 21 is completely penetrated by the treatment fluid across its whole thickness. in example 1, the impregnation of the fibre mass is effected according to the method from the prior art by spraying the treatment fluid onto the fibre mass in the conveying direction downstream of the press-roll. In this method, the fibre mass 21 is not completely penetrated immediately after the contact with the treatment fluid, so that the treatment fluid accumulates like a lake above the fibre mass and only gradually trickles through the fibre mass 21. This formation of a lake is increased as the thickness of the fibre mass is increased. A complete penetration of the fibre mass with the treatment fluid is only achieved after a relatively long dwell time of the fibre mass in the treatment zone. To this end, the treatment zone has to comprise a corresponding length in the conveying direction of the fibre mass through the treatment device. In example 2, the treatment is in contrast accomplished with a press-roll designed according to the invention with treatment conditions otherwise identical to example 1. As can be seen from the table when comparing examples 1 and 2, in example 1, i.e. the solution of the prior art, the fibre throughput per m2 of the treatment zone and per hour is considerably lower than in example 2. In the examples 3 to 5, the press-rolls according to the invention are also used, so that the fibre mass is immediately penetrated when contacted by the liquid and long treatment fields for the complete penetration of the fibre mass are not necessary. Moreover, in these embodiments an essentially more uniform and faster distribution of the treatment fluid in the fibre mass are the consequence. Method and device for treating a fibre mass The invention relates to a method for treating a fibre mass, such as a woven cloth or a nonwoven, where the fibre mass is conveyed through a pressing mill, where the fibre mass is pressed in at least one pressing zone by the pressing surface area of at least one press-roll by means of a pressing power acting on the fibre mass, and the pressed fibre mass is impregnated with a treatment fluid, the fibre mass being passed through an expansion region in the pressing zone where the pressing power is reduced in the passing direction of the fibre mass. The invention further relates to a press-roll arrangement for treating a fibre mass moving relatively to the press-roll arrangement, comprising a press-roll with a pressing surface area by means of which in operation in a pressing zone a pressing power acting on the fibre mass is generated, and with an impregnation means by which in operation a treatment fluid is supplied to the fibre mass, the pressing zone forming an expansion region in operation in which the pressing power is reduced in the moving direction of the fibre mass. The term pressing surface area designates the surface which limits, as an imaginary or actually existing surface area, the pressing zone from the upper or lower side of the fibre mass, i.e. the idealized enveloping surface via which the pressing power acts on the fibre mass. For preparing the fibre masses concerned by the invention, conventionally a polymeric mass is melted or dissolved in a solvent and subsequently drawn over spinning devices to form filament yarns. For preparing the filament yarns, various spinning processes, such as dry spinning and wet spinning methods or a combination of dry and wet spinning methods, are possible. In the process, the filaments are generated in a spinning machine and drawn off from the same by one or more draw-off elements being at the same time formed to filament bundles or tows. Subsequently, the filaments are washed and aftertreated in further processing steps. Before the aftertreatment, for example, in the manufacture of staple fibres, the tow of filament yarns arranged in parallel which is drawn off from the spinning machine is supplied to a cutting device. After exiting the cutting device, in general a nonwoven is formed from the individual staple fibres and deposited on a transport device to be further treated. The staples are generated by staple cutting machines, for example in a dry cut by the machine described in "Ullman Volume 11, Fasern-Herstellungsverfahren", pages 249-289. Viscose fibres are spun in general in aqueous media as cellulosic regenerated fibres. For the staple fibre generation from the continuously spun fibre tow, for example a cutting machine is suitable which essentially consists of a pair of rolls for feeding the spinning tow to the cutting apparatus, the actual cutting apparatus and a staple fibre washing-down device. The cutting apparatus draws the tow fed by the draw-off element by means of a water jet injector to the horizontally rotating cutting knives. The cutting knives maintain their edge retention during the cutting process by a continuous regrinding. Moreover, by the water jet supply, a first dissolution of the staple fibre stacks formed during the cutting process is effected before the suspension of the staple fibre stacks at the aftertreatment machine. Such a machine is for example manufactured by the company Ing. A. Maurer S.A. The aftertreatment of for example viscose fibres can or must be effected by various treatment steps. In the process, in aftertreatment machines for viscose fibres, typically the following treatment steps are carried out while supplying a treatment fluid: deacidification, desulphurization, washing, bleaching and washing, antichlorine treatment, washing with water as well as applying an avivage or a fat coat. These treatment steps are conventionally carried out in a device to which the cut staple fibre, also designated as "flock", comes from the cutting machine via a washing-in device while forming a nonwoven coat distributed as uniformly as possible. The device for treating the fibre mass is conventionally formed as a long aggregate in which the fibre mass distributed to a uniform nonwoven or the fibre mass, respec- lively, is conveyed on a transport means through the individual treatment zones. As a transport means, a belt conveyor, for example with an endless travelling screen or an endless wire-cloth belt, an oscillating conveyor or an eccentric notched conveyor can be used. In the treatment of the fibre mass, care has to be taken that the treatment fluids supplied in the individual treatment steps are quickly and homogenously distributed in the suspended nonwoven. At the same time, it is advantageous to remove the treatment fluid from the previous treatment step as completely as possible from the fibre mass before carrying out a treatment step. For removing a treatment fluid from the fibre mass, conventionally a press-roll arrangement is used which exerts a pressing power on the fibre mass. By means of the pressing power, the treatment fluid is pressed out of the fibre mass. In the subsequent treatment step, the pressed fibre mass is then impregnated with the treatment fluid associated to this treatment step. That is, by means of the press-roll arrangement, two subsequent treatment steps are separated. In the region where the pressing power acts on the fibre mass, i.e. the pressing zone, shortly after the point of the highest pressing power, a region is formed where the pressing power is reduced in the conveying direction of the fibre mass. This region is designated as expansion region. In order to moisten the fibre mass with the treatment fluid, conventionally the fibre mass is passed below spray tubs on a transport device. Directly after the pressing out, the treatment fluid is dripped onto the fibre mass by spray installations positioned thereabove. However, the application of the treatment fluid by dropping only effects a nonuniform impregnation and moistening of the fibre mass just pressed. A special problem arises in the preparation of cellulose fibres or nonwovens of cellulose fibres which are prepared by an NMMO or lyocell process. In the process, a spinning solution containing water, cellulose and tertiary amine oxide is extruded to a filament yarn and drawn. During the drawing, the cellulose filaments are exposed to a high mechanical stress. The filaments and staple fibres prepared according to the NMMO or lyocell process comprise a high crystallinity or orientation of the cellulosic molecules, respectively. Due to these product features caused by the manufacturing process, lyocell fibres tend to be fibrillary. Fibrillation means that due to the high crystallinity and orientation small fibrils split off the circular fibre surface of an individual fibre. The formation of fibrils continues along the fibre axis. In order to reduce the tendency of fibrillation, the fibre can be treated with chemical cross-linkers which bind the fibrillary elements to the fibre main body. In general, an interlacing or cross-linkage process is controlled such that the cellulosic fibre tow is impregnated with a chemical cross-linking agent and the cross-linking reaction is started by vaporization at elevated temperatures. The cross-linking agents have to be homogenously introduced into the fibre mass after the fibre preparation, the temperature of the fibre optionally has to be controlled and washed out of the fibre in subsequent treatment steps. Moreover, the cellulose fibre has to be brightened and dried, as other non-cellulosic fibres as well. In this treatment, it is problematic that the cross-linking agents tend to spontaneous chemical degradation or hydrolysis reactions as the chemicals hydrolise in an aqueous medium or are not stable for a long time, respectively. If the reaction parameters - for example the reaction rate or the reaction temperature - are not exactly observed, degradation or decomposition reactions can also occur. Therefore, the cross-linking agent has to be introduced in closed regions while controlling the reaction course as exactly as possible. Usually, the cross-linking agents require a quick introduction into the cellulose fibre with a subsequent quick control of the temperature as well as subsequently a washing out of the remaining chemicals as fast as possible with a cooling-down at the same time. During the so-called cross-linkage, elevated temperatures as well as alkaline or acid liquids act on the fibre mass. The chemical reaction of the cellulose with the cross-linking agent is effected at elevated pH-values (for example approx. 11-14), resulting in a hydrolysis of the cross-linking agent. The cross-linking agent's tendency of decomposition can be repressed by the temperatures in the cross-linking bath being as low as possible. The low temperatures can be adjusted in or in front of the pressing device. After the thermal fixation of the cross-linking agent, i.e. the reaction of the cross-linking agent with the cellulose chains between approx. 20 and 98°C, the alkali has to be removed from the fibre mass for reducing the strain on the cellulosic fibre. Due to the high fibre density and fibre swelling in cellulosic fibre masses, moreover long dwell times for penetrating the fibre mass are necessary, as only a low geodetic height of the liquid positioned thereabove acts on the nonwoven and the pressure losses of the nonwoven can only be overcome by a long action duration of the fluid. The conventional method and the conventional device, where the pressed fibre mass is only sprayed with a treatment fluid, are not sufficient for a precise control of the process parameters exactly in treatment fluids which chemically react easily or decompose, such as cross-linking agents. In view of the methods and devices conventionally employed for treating fibre masses, it is therefore an object of the invention to improve the method mentioned in the beginning and the device mentioned in the beginning, respectively, in such a way that a distribution of the treatment fluid, the temperature-controlling agent (hot water, hot vapour and optionally other heat transfer media) as well as various washing media in the fibre mass as fast and homogenously as possible and thus also an exact process control are possible. This object is achieved for the inventive method mentioned in the beginning in that the treatment fluid is passed into the fibre mass in the expansion region through the pressing surface area. In the press-roll arrangement mentioned in the beginning, this object is achieved in that the press-roll arrangement comprises openings in the expansion region through which in operation the treatment fluid is passed through the pressing surface area into the fibre mass. This solution is simple and has the advantage that the treatment fluid very quickly and homogenously distributes in the pressed and compressed fibre mass which relaxes in the expansion region. As in the expansion region the pressing power is reduced in the moving direction of the fibre mass, in this region the fibre mass automatically takes in the treatment fluid through the pressing surface area. Thus, a uniform and quick penetration of the pressed fibre mass with the treatment fluid already takes place in the pressing zone. Thereby, the treatment process is easier to control. The solution according to the invention has the further advantage that the overall length of a treatment machine can be essentially reduced. In contrast to the conventional machines, where due to the spraying a penetration of the fibre mass is only possible by means of a long action time and a correspondingly longer conveying distance of the fibre mass through the treatment zone, with the solution according to the invention due to the immediate penetration the next treatment step can directly follow the impregnation of the fibre mass with the treatment fluid. That is, with the solution according to the invention, it is possible to design the pressing mill similarly to a rolling mill where the individual rolls directly follow one another in the direction of rolling. According to a further development of the invention, accordingly in the treatment of the fibre mass several treatment steps can be carried out successively by passing the fibre mass successively through several press-roll arrangements, in one press-roll arrangement each a first treatment fluid being pressed out of the fibre mass in the compression zone and the fibre mass being impregnated with a second treatment fluid in the expansion zone. The fibre mass can be conveyed through the pressing zone by means of a separate conveying means, for example in the form of a conveyor belt, the press-roll passively rotating along. However, the press-roll can also be provided with an own driving means. In this case, one can dispense with a separate conveying means, as the press-roll itself forms the conveying means. The peripheral speeds of the press-rolls can be between 0.1 and 400 m/min, preferably between 0.1 and 60 m/minT in particular between 0.1 and 10 m/min. With these peripheral speeds, in a treatment zone a fibre throughput of 10 to 1500 kg/(m2h), preferably between 10 and 1200 kg/(m2h), can be achieved. The fibre throughput is calculated from the weight of the fibre mass in an absolutly dry condition divided by the dwell time per treatment field and is independent of the length of the treatment field. In front of the expansion region, the fibre mass can be passed in the pressing zone through a compression region where the pressing power is increased in the conveying direction of the fibre mass, so that a treatment fluid already present in the fibre mass is pressed out. In a further advantageous embodiment, in the compression region the pressed out treatment fluid can be let off from the fibre mass through the pressing surface area. For doing so, for example a suction means can be provided through which in operation the treatment fluid is sucked off from the compression region. Instead of a suction means, however, only openings in the pressing surface area can be provided through which the treatment fluid automatically passes due to the pressing power increasing in the treatment direction in the compression region, so that after the passage of the fibre mass through the pressing zone almost no more treatment fluid from the previous treatment step is contained in the fibre mass. The line pressure with which a press-roll according to the invention is pressed into the fibre mass is up to 100 N per mm of the roll width. As a supplement or alternatively to the letting off or sucking off of the treatment fluid in the compression zone, a treatment fluid can also be passed in the compression zone through the pressing surface area into the fibre mass for rinsing the fibre mass before pressing it. For example, the fibre mass can be rinsed with the treatment fluid supplied to the upstream press-roll in the expansion zone, so that no treatment fluid from the treatment step which is arranged by the device in front of the compression zone in the transport or conveying direction of the fibre mass, can be carried into the treatment step which is arranged behind the expansion zone in the conveying direction. A thorough and uniform impregnation of the fibre mass with the treatment fluid can be achieved if according to a further advantageous embodiment the treatment fluid is pressed into the fibre mass under pressure, for example by nozzles arranged in the pressing region in the compression and/or expansion region. The liquid throughput referring to the press-roll width can be between 0.1 and 125 m3/(h m), preferably between 0.1 and 50 m3/(h m), in particular between 0.1 and 20 m3/(h m). A particularly compact construction can be achieved if the impregnation means through which the treatment fluid is supplied to the fibre mass is arranged at least by sections within the press-roll. In this case, according to a further embodiment of the invention, the treatment fluid can be conveyed from the inside of the press-roll through openings into the fibre mass. For doing so, the press-roll can be provided with openings at its surface facing the fibre mass through which openings the treatment fluid is conveyed into the fibre mass. The openings can be formed in the surface of the press-roll regularly or irregularly and for example comprise a cross-section which is essentially nozzle-like. The opening degree of the roll, i.e. the relation of the surfaces occupied by the openings to the overall surface of the roll, can be between 1 and 95%, preferably between 3 and 90%, particularly preferred between 3 and 85%. According to another embodiment, the press-roll can, however, form ribs at its surface facing the fibre mass, which form at least by sections the pressing surface area and between which in operation the treatment fluid can be introduced into the fibre mass. According to further embodiments, these ribs can extend essentially transverse to or essentially in the moving direction of the fibre mass. In order to avoid a carrying away or mixing of the treatment fluids from the two treatment steps separated by the press-roll arrangement, according to a further advantageous embodiment, the ribs can be designed as a weir which acts against a flow of the treatment fluid through the press-roll from the compression region to the expansion zone and thus acts against a carrying away of the treatment fluid. This is in particular possible if the ribs extend transversely to the moving direction of the fibre mass. To this end, the height of the ribs can be dimensioned such that in the pressing zone an upper end of a rib facing away from the fibre mass projects essentially between the compression region and the expansion region always above the level of the treatment fluid in the compression region and/or expansion region. In particular in the embodiment of the press-roll with ribs being spaced apart and preferably extending transversely to the conveying direction of the fibre mass, spray nozzles can be integrated inside the press-roll according to a further advantageous embodiment, through which the treatment fluid is directed in operation onto the fibre mass preferably in the pressing zone in a spray or jet form. In order to avoid a conveyance of the treatment fluid out of the compression region through the rotating press-roll into the expansion region, the nozzles can also be directed to the compression region in order to dilute or displace the treatment fluid present therein. A complete moistening of the fibre mass by the treatment fluid delivered by the spray nozzles is achieved if the atomizing cone of the nozzles essentially overlaps in the region of the fibre mass or in the pressing zone, respectively. Depending on the type of the treatment fluid used, the size and weight of the fibre mass as well as the composition of the fibre mass, it can be necessary to regulate the region via which the treatment fluid is conducted through the pressing surface area onto the fibre mass. For doing so, the impregnation means can comprise a regulation means by which the size and the orientation of the exiting region of the treatment fluid in the pressing surface area is regulated. To this end, according to a further advantageous embodiment, the regulation means can be designed as a cover body arranged in the press-roll with a slot arranged in the press-roll, which covers that part of the pressing surface area or the press-roll through which no treatment fluid is to pass. This cover body can for example be designed as a tubular body provided with a longitudinal slot and rotatably held in the press-roll. Instead of or in addition to a supply line of the treatment fluid from the inside of the press-roll, the impregnation means can comprise a supply line through which in operation the treatment fluid is conveyed from outside the press-roll essentially into the expansion region. This supply line can be arranged according to a further advanta- geous embodiment at least in the pressing zone at least by sections between two ribs essentially extending in the moving direction of the fibre mass. In this case, it is advantageous if the section of the supply line facing the pressing surface area essentially flushes with the ribs, so that the pressing surface area is as smooth as possible and offers only little frictional resistance with respect to the fibre mass. Finally, the invention also relates to a pressing mill for treating fibre masses with at least one press-roll arrangement for pressing the fibre masses and with a conveying means for conveying the fibre masses through the pressing mill, a press-roll arrangement according to one of the above described embodiments being used. In a pressing mill with several press-roil arrangements successively arranged in the conveying direction of the fibre mass, the press-roll can directly follow one another. The pressing mill and the press-roll arrangement can be operated with a fibre mass of which the absolutely dry weight per surface unit is between 0.1 to 20 kg/m2, preferably 0.1 to 10 kg/m2. As fibre masses, tows or heavy, thick nonwovens can be af-tertreated. As treatment fluids, pure water, aqueous organic or inorganic solvents, aqueous or concentrated alkaline solutions or acids, bleaching chemicals, preparation means or inert gases, respectively, vapour-like media, heating or cooling media as well as solvent vapours can be used. Opposite the press-roll, a further press-roll can be arranged in the pressing mill in the region of the pressing zone which serves as counterpressure means for taking up the pressing power. This second press-roll can have the same design as the above described first press-roll. In this configuration, the fibre mass is passed between the two press-rolls. As materials for the press-rolls, metals or plastics can be used the surface of which can be rubberized, polished or ground. In order to avoid a damage of the fibres, the edges of the press-rolls and optionally the edges of the openings and ribs arranged at the press-rolls should be broken. In the following, the invention is further illustrated as to its construction and function with reference to embodiments. In the drawings: Fig. 1 shows a schematic representation of a plant for manufacturing a fibre mass; Fig. 2 shows a cross-section of a first embodiment of a press-roll arrangement according to the invention; Fig. 3 shows a cross-section of a further development of the embodiment of Fig. 2; Fig. 4 shows a perspective view of a second embodiment of a press-roll arrangement according to the invention; Fig. 5 shows a cross-section of the embodiment of Fig. 4; Fig. 6 shows a perspective view of a third embodiment of the press-roll arrangement according to the invention; Fig. 7 shows a front view of the embodiment of Fig. 6; Fig. 8 shows a cross-section of a fourth embodiment of a press-roll arrangement according to the invention. First, the course of the method for manufacturing the fibre mass is described with reference to Fig. 1. In a system 1 only schematically represented in Fig. 1, an extrusion solution 2 is prepared. To this end, in one or more mixers a suspension of dry or wet crushed cellu- lose and water and/or tertiary amine oxide is formed. Employing elevated temperatures at low pressure, water is volatilised from the suspension to such an extent that a cellulose solution serving as an extrusion solution is formed. In a reaction vessel 1, an extrusion solution 2 is prepared. The extrusion solution contains cellulose, water and tertiary amine oxide, such as N-methylmorpholine-N-oxide (NMMO), as well as optionally stabilisators for thermally stabilizing the cellulose and the solvent. Examples of stabilisators are: propyl gallate or media having alkaline effects or mixtures thereof. Optionally, further additives can be contained, such as titane dioxide, barium sulphate, graphite, carboxymethylceiluloses, polyethylene glycols, ketine, ketusane, alginic acid, polysaccharides, colorants, antibacterially acting chemicals, flame protection agents containing phosphor, halides or nitrogen, active carbon, carbon blacks or electroconductive carbon blacks, silicic acid as well as organic solvents as diluting agents, etc. The extrusion solution 2 is delivered through a line or conduit system 4 via a pump 3. In the line system 4? a pressure compensation vessel 5 is arranged, which compensates pressure and/or volume flow fluctuations in the line system 4, so that an extrusion head 6 can be continually and uniformly provided with the extrusion solution 2. The line system 4 is provided with means to control the temperature (not shown) by which the temperature of the extrusion solution 2 taken as an example herein can be precisely controlled, as well as with a filtration unit (not shown). This is necessary, as the chemical and mechanical characteristics of the extrusion solution greatly depend on the temperature. Thus, the viscosity of the extrusion solution 2 is reduced as the temperature and/or the shearing rate are increased. In the line system 4, furthermore bursting protection means are provided, which are necessary due to the tendency of the extrusion solution towards a spontaneous exothermic reaction. Due to the bursting protection means, in case of a spontaneous exothermic reaction, damages of the line system 4 and the pressure compensation vessel 5 as well as the downstream extrusion head 6, as they can occur due to the reaction pressure, are avoided. A spontaneous exothermic reaction in the extrusion solution 2, for example, occurs when a certain temperature is exceeded or in case of an ageing of the extrusion solution 2, particularly in dead water zones. In order to avoid the occurrence of dead water zones and burblings and to ensure a uniform flow of the extrusion solution through the line system 4, the line system 4 is formed so as to enhance flows in the overall region through which the highly viscous extrusion solution flows. In the extrusion head 6, the extrusion solution is distributed to a plurality of extrusion ducts 8 in the form of spinning capillaries in a nozzle space 7. The spinning capillaries 8 are arranged in line, in Fig. 1 perpendicularly to the plane of projection. By means of a single extrusion head 6, thus a plurality of continuous moulded products is prepared simultaneously. Moreover, a plurality of extrusion heads 6, each forming a plurality of continuous moulded products or, in case of the embodiment of Fig. 1, filaments, can also be provided. In Fig. 1, only one spinning capillary 8 is shown for the sake of simplicity. Normally, the spinning capillary has an internal diameter D of less than 500 ^m, for special applications, the diameter can also be less than 100 [am, preferably about 50 to 70 (am. The length L of the spinning capillary through which the extrusion solution flows, is at least twice the internal diameter D, maximally 100 to 150 times the internal diameter D. The spinning capillary 8 is at least sectionwise surrounded by a heating means 9 by which the wall temperature of the spinning capillary 8 can be controlled. The wall temperature of the spinning capillary 8 is in operation about 150°C. The temperature of the spinning solution is in operation between about 80 and 130°C. The spinning capillaries 8 can also be disposed in an arbitrary form in a carrier body, the temperature of which is controlled from the outside, so that the hole densities in the extrusion head 6 are high. The heating means 9 preferably extends to the outlet 10 of the extrusion duct situated in the flow direction S. Thereby, the wall of the extrusion duct 8 is heated down to the extrusion duct opening 10. Due to the direct or indirect heating of the extrusion duct, at the internal wall thereof and due to the viscosity of the extrusion solution depending on the temperature, a heated film flow having a low viscosity as compared with the central flow is formed. Thereby, the velocity profile of the extrusion solution within the extrusion duct 8 and the extrusion process are positively changed such that an improved loop stability and a reduced fibrillation tendency of the extruded spinning solution are achieved. In the extrusion duct 8, the extrusion solution is extruded and subsequently exits in the form of a filament 11 in an air gap 12. In the flow direction S of the extrusion solution, the air gap has a height H. In the air gap 12, air 13 is supplied at a high velocity to the extrusion solution from the extrusion head 6. The flow direction can be guided horizontally up to the extrusion filament; the flow velocity of the air 13 can be higher than the extrusion velocity of the filament at which the continuous moulded product exits the extrusion duct opening 10. Due to an air flow which is essentially guided coaxially, a tensile stress acts at the boundary surface between the continuous moulded product 11 and the air 13, which stress can draw the continuous moulded product 11. After having passed the air gap 12, the continuous moulded product enters a coagulation bath zone 14 where it is wetted or moistened with a coagulation solution. The wetting can either be effected by means of a spraying or moistening device (not shown) or by immersing the continuous moulded product 11 in the coagulation bath. Due to the coagulation bath solution, the extrusion solution is stabilized. A further possibility is to deposit the continuous moulded product 11 essentially without tensile stresses downstream of the coagulation bath zone 14 on a conveyor means 15. The conveyor means 15 is equipped as a vibrating conveyor. Due to the to-and-fro movement of the vibrating conveyor 16, the continuous filaments are deposited on the conveyor means in straightened staples 17. Due to the conveyance on the conveyor means 15 without tensile stresses, the continuous moulded product 11 can stabilize without detrimental effects acting on the mechanical characteristics of the continuous moulded product 11, as they can, for example, occur by a premature mechanical load shortly after the extrusion of the continuous moulded product 11. Depending on the design, the continuous moulded product 11 is drawn off by means of a draw-off work 18 upstream or downstream of the conveyor means 15 and supplied to a cutting machine 20 via deflection or conveyor means 19. Via the draw-off work 18, the corresponding fibre parameters, such as titer, stability and stretching, are regulated. The continuous moulded products 11 only of a part of the extrusion heads 6 or of all extrusion heads 6 are introduced into the cutting machine 20 in parallel. In the cutting machine 20, there is positioned a pair of rolls (not shown) for supplying the continuous moulded product bundles 11 of the various extrusion heads 6 to the cutting apparatus, the actual cutting apparatus (not shown) and a staple fibre washing-down device. The cutting apparatus (not shown) draws the tow fed by the pair of draw-off rolls by means of a water jet injector to horizontally rotating cutting knives. By means of the cutting knives, the fibre mass is cut to a predetermined length. The cutting knives maintain their edge retention during the cutting process by a continuous regrinding. By the water jet supply, a first dissolution of the staple fibre stacks formed during the cutting process is effected before the suspension of the staple fibre stacks to form a fibre mass. An essentially mat-like fibre mass 21 exits from the cutting machine 21, which mass, together with the water supplied during the cutting operation, is washed into a device 22 for treating the fibre mass 21. The fibre mass 21 is formed by a random orientation of the fibres cut in the cutting machine 20. The device 22 for treating the fibre mass 21 essentially constitutes the subject matter of the present invention. In the device 22, treatment steps typical of viscose fibres are accomplished, such as deacidification, desulphurization, washing, bleaching and washing, antichlorine treatment, washing with water as well as applying an avivage/fat coating or other chemicals. The individual treatment steps or phases, respectively, each take place in treatment zones 23, 24, 25, 26, 27, which are separated from one another by press-roll arrangements 28, 29, 30, 31, 32, 33. In each treatment zone 23 to 27, via an impregnation means 34, 35, 36, 37, 38 a treatment fluid each associated to this treatment zone or treatment step, respectively, is fed from corresponding reservoirs 39, 40, 41, 42, 43. The treatment zones have a distance of at least about 0.5 m from roll center to roll center in the conveying direction of the fibre masses, however, the distance can be up to 10 m and more depending on the requirement of the treatment operation. In an extreme case, the individual press-roll arrangements 28, 29, 30, 31, 32, 33 can, however, also directly follow one another, so that the press-rolls just do not contact. In the process, the reservoirs 39 to 43 are provided with treatment fluid in a reverse flow, i.e. the treatment fluid from a consecutive step in the conveying direction B of the fibre mass 21 is fed to an upstream treatment step in the treatment direction essentially without being cleaned; the direction of the flow of the treatment fluid through the device 22 is opposite to the conveying direction of the fibre mass 21 through the device 22. In the conveying direction B, consequently the purity of the treatment fluid in the reservoirs 39 to 43, which are disposed as collecting vessel below the fibre mass 21, is increased. The fibre mass 21 is conveyed by the device 22 on a conveyor means 44 which can be designed as endless travelling screen or an endless wire-cloth belt, an oscillating conveyor or an eccentric notched conveyor. The press-roll arrangements 28 to 33 can be designed either, as shown in Fig. 1, as paired rolls or as individual rolls with a fixed counterpressure face. The force of the pressure of the rolls can be generated electrically, hydraulically or pneumatically as well as mechanically, for example by means of leverages. The typical force of pressure of the press-roll is up to approximately 100 N per mm of the roll width. Due to the pressing power exerted by the press-roll arrangements 28 to 33, the treatment fluid introduced into the respective treatment zone 23 to 27 is pressed out of the fibre mass and the treatment fluid is prevented from being carried away from a previous treatment step to the next treatment step. After having passed the device 22, the fibre mass 21 can be fed to further treatment steps not shown in Fig. 1. For example, a drying device with opening aggregates for dehumidifying and relaxing the fibre mass and consecutively a packaging aggregate for manufacturing a product ready for shipping can follow. Fig. 1 shows an example of the preparation of a fibre mass from a spinning solution containing cellulose. However, the use of the device 22 is not restricted to cellulose fibres but can be also used for nonwoven-like or woven fibre masses of filaments of other compositions. For preparing such fibre masses of non-viscous or non-cellulosic fibres, other manufacturing methods are known from the prior art. In the following, one press-roll arrangement each is described by way of example. As the basic function of the press-roll arrangements 28 to 33 is the same in each case, in the following description only one single press-roll arrangement is discussed by way of example. i Fig. 2 shows a first embodiment of a press-roll arrangement 50 according to the invention for treating the fibre mass 21 in a section perpendicular to the moving direction B of the fibre mass 21. The press-roll arrangement shown in Fig. 2 is used for washing the tow or the staple ) fibres with low speeds and large fibre masses, the fibre mass being moved at a speed of approximately 40 m/min in the conveying direction. This speed corresponds to the extrusion rate of the continuous moulded products at the extrusion head. With a basis weight of the fibre mass of 0.1 kg/m2 when absolutely dry, the fibre through- put is approx. 52 kg/(m2h), the treatment fluid being fed at a flow rate of 125 rrr7(h m) per m of the roll width. The press-roll arrangement 50 comprises a press-roll 51 which is rotatably mounted in a bearing not shown in Fig. 2 and rotates along with the motion of the fibre mass 21 in the direction of the arrow P. The press-roll 51 is pressed into the fibre mass 21 with a force of pressure F. In the process, a pressing surface area 52 which is the idealized enveloping surface about the press-roll 51 by which the pressing power generated by the force of pressure F acts on the fibre mass 21, is formed. The region across which the force of pressure F acts as pressing power on the fibre mass 21 via the pressing surface area 52 is designated as pressing zone 53. in the moving direction B of the fibre mass 21, in the pressing zone first of all the pressing power is increased up to approximatley the region where the press-roll 51 maximally penetrates the fibre mass 21. The region of the pressing power increasing in the moving direction B of the fibre mass is hereinafter referred to as compression region 54. Following the compression region 54 in the moving direction B of the fibre mass 21 is an expansion region 55 where the pressing power is again reduced in the moving direction B of the fibre mass. In the compression zone 54, due to the increased pressing power the treatment fluid 56 taken up in the fibre mass 21 is pressed out, so that following the compression zone 54 nearly no more treatment fluid 56 from the previous treatment step is present in the fibre mass 21. In the embodiment of Fig. 2, the press-roll 51 is provided with passages 57 which extend from the inside of the press-roll to the outside of the press-roll. At the outer peripheral surface 59 of the press-roll 51, the passages 57 end in recesses 58, the diameter of which is larger than the diameter of the passages 57. The passages can also be attached slit-like along the press-roll axis and be correspondingly distributed across the periphery. The diameter of the bores is 3 to 12 mm with a roll diameter of 400 mm. The opening degree of the press-roli 51 is approximately 5 to 40%, largely independent of its diameter. The through bores 57 can be distributed arbitrarily, in rows in the axial direction or in the peripheral direction or set off relative to one another at the outer peripheral surface 59. In the embodiment of Fig. 2, the inside of the press-roll forms a part of the impregnation means through which treatment fluid is introduced into the fibre mass. Inside the press-roll 51, a cover body 60 is provided, which has an essentially tubular design and comprises an opening 61 extending in the axial direction of the press-roll 51 in the form of a slit facing the pressing zone. The cover body 60 does not move along with the press-roll 51 but is stationary. At each of its ends facing the slit, the cover body 60 is provided with sealing elements 62, so that no treatment fluid from the interior space 63 of the press-roll 51 can come between the cover body 60 and the internal peripheral surface 64 of the press-roll 51. The cover body 60 serves for defining the region 65 via which treatment fluid is introduced into the fibre mass 21. The region 65 extends according to Fig. 2 mainly into the region of the expansion zone 55, but also - at least by sections - into the region of the compression zone 54. If treatment fluid, which can be, for example, under a pressure of 2.5 to 3 bar, is conducted from the interior space 63 of the press-roll 51 through the passages 57, this treatment fluid will wash out the treatment fluid 56 from the previous treatment step in the compression zone 54, as schematically indicated . in Fig. 2, and at the same time it will be absorbed in the expansion zone 55 by the capillary action and the swelling of the fibre mass 21 due to the reducing pressure. As a result, a homogenous and fast distribution of the treatment fluid supplied through the press-roll 51 or the pressing surface area 52, respectively, is achieved. In ) order to be able to adjust the position of the slit 61 relatively to the pressing zone 53, the first cover body 60 is coaxially held in the press-roll 51 to be pivoted about its longitudinal axis X, as implied by the double arrow A. Fig. 3 shows a further development of the embodiment of Fig. 2. Here, below only the differences to the embodiment of Fig. 2 are discussed. The press-roll arrangement of Fig. 3 can, for example, be used for washing a cellulose nonwoven as fibre mass 21 having a weight of approximately 4.1 kg/m2. In this application, the fibre mass is moved in the conveying direction at a rate of approx. 0.1 m/min. The fibre throughput per m of the roll width is about 40 kg/(h m2) with such an application. The treatment fluid is supplied with a throughput of 0.7 m3/(h m). In contrast to the one-piece cover body 60 of Fig. 2, the cover body is divided into two cover bodies 60a and 60b in the further development of Fig. 3. Each of the two cover bodies 60a, 60b is held independently of the other cover body at the inner peripheral surface 64 of the press-roll 51 to be pivoted about the longitudinal axis thereof. Thus, in the press-roll arrangement 50 according to Fig. 3, the opening angle a as well as the orientation of the slit 61 can be changed by adjusting one of the cover bodies 60a, 60b or both cover bodies 60a, 60b. In order to seal the interior space 63 of the press-roll 51 outside the slit region, a sealing body 66 is provided which covers a moving slit 67 which is also formed by the two cover bodies 60a, 60b and ensures the movability of the two cover bodies 60a, 60b relative to one another. The sealing body 66 can be arranged within the cover bodies 60a, 60b or, in an alternative embodiment, between the cover body 60a, 60b and the press-roll 51. At its ends, the tubular sealing body 66 provided with a longitudinal slit is provided with sealing elements 68 which avoid the penetration of treatment fluid between the cover body and the sealing body. In the embodiment of Fig. 3, due to the high variability with respect to the size and position of the treatment zone 65, an exact adaptation to the respective treatment step and the moistening requirements of the treatment fluid fed into this treatment step can be effected. In phantom lines, for example a one-sided adjustment of the left cover body 60b is shown in Fig. 3, resulting in a treatment zone 65 being only situated in the expansion region 55, through which the treatment fluid is introduced into the fibre mass 21. A second embodiment of a press-roll arrangement according to the invention is represented in Fig. 4. Here, for elements the design or function of which essentially correspond to the elements of the previous embodiment, the same reference numerals are used. In the embodiment of Fig. 4, the press-roll 51 is formed of a plurality of ribs 70 extending in the axial direction X of the press-roll 51. The ribs have a wall thickness which increases in the radial direction from the inside of the press-roll 51 to the outside. At their outer side, the ribs 70 at least by sections form the pressing surface area 52 in the pressing zone 53. The ribs 70 are each fixed at mounting plates or rings at the two ends of the pressing surface area positioned in the axial direction X. The ribs 70 all extend in parallel to one another and are equally spaced apart from one another, the region 71 between them is essentially free of materials. The ribs 70 can be interconnected by plate- or ring-like struts extending in the peripheral direction, so that they obtain a higher mechanical stability. In the embodiment represented in Fig. 4, the opening degree of the press-roll 40 can be in individual cases up to between 90 and 95%. The number of ribs is between 30 and 80, preferably about 60. With a diameter of the press-roll of 400 mm, the width of the rib can be between 1 and 20 mm in the peripheral direction, using broader struts leads to a higher pressure, but a lower flow rate. In the interior space 63 of the press-roll 51, an impregnation device 72 is arranged, through which treatment fluid is guided into the interior space 63 of the press-roll 51. Such an impregnation means 72 can for example alternatively also be used in the embodiment of Fig. 2 instead of or together with the cover body 60. Inversely, the impregnation means can also be used according to the embodiment of Fig. 2 or 3 together with the cover body 60 described therein. The impregnation means 72 of the embodiment of Fig. 4 consists of a central supply line 73 extending coaxially to the axis X of the press-roll 51. The supply line 73 is represented in Fig. 4 cut at its end positioned in the axial direction X, however, at its right end in Fig. 4, an end cap can be provided, or the supply line 73 can extend through all of the press-roll 51 in the axial direction X and supply the treatment fluid to a further press-roll arrangement. The end of the supply line 73 in the flow direction S of the treatment fluid can be connected with the inlet of the supply line 73 in order to make possible a recycling of the treatment fluid in this treatment step. The impregnation means 72 is further provided with one or a plurality of spray nozzles 74 which are directed to the fibre mass 21. The treatment fluid flows from the central supply line or the collective tube 73 through the individual nozzles 74 and between the ribs 70 into the fibre mass 21. Fig. 5 shows a section perpendicular to the axial direction X of the embodiment of Fig. 4. In Fig. 5, one can see that the treatment fluid from each of the spray nozzles 74 forms an atomizing cone 75, the atomizing cones 75 overlapping such that in the pressing zone 53 there is no region which is not moistened by the treatment fluid. The atomizing cones 75 can be conical or even. In order to prevent the treatment fluid 56 from being carried away into the region situated downstream of the pressing zone 53 in the moving direction B of the fibre mass 21, the height H of each rib 70 is dimensioned such that the ribs essentially situated in the pressing zone 53 form a weir through which a direct flow of the treatment fluid between the regions at both sides of the pressing zone is not possible. As by the rotation D of the press-roll 51 treatment fluid could be conveyed from one treatment step to the next treatment step through the space 71 between two ribs 70, a spraying nozzle 74' is directed to the compression zone in order to wash out treat- merit fluid 56 possibly flowing in from the previous treatment step. Via a regulation means 76, for example by the spraying nozzles 74 being attached to tubes 76 rotatable relative to one another and being concentric to the supply line 73, the treatment region 65 can be regulated with respect to size and orientation by adjusting the spray nozzles 74. The distance between the ribs in the peripheral direction is dimensioned such that a sufficient amount of treatment fluid can pass between the ribs and at the same time the pressing power in the pressing zone 53 can still uniformly act on the fibre mass 21. Fig. 6 shows a perspective view of a third embodiment of a press-roll arrangement 50 according to the invention. Here, for elements the design and function of which correspond to an element of the previous embodiments, the same reference numerals are used as in the previous embodiments. The press-roll 51 of the embodiment of Fig. 6 comprises ribs 70 spaced apart in the axial direction X of the press-roll 51 between which a space 71 is formed. The press-roll arrangement 50 further comprises two impregnation means 72a, 72b, which are arranged at both sides of the press-roll 51 with respect to the moving direction B of the fibre mass not shown in Fig. 6 for the sake of simplicity. Each impregnation means 72a, 72b comprises a collective tube 73 extending in parallel to the axial direction X of the press-roll 51 from which supply lines 80 extend into the spaces 71 between the ribs 70 down into the pressing zone 53. In the embodiment of Fig. 6, the supply lines 80 of the two impregnation means 72a and 72b are interconnected in one piece, so that the treatment fluid from the collective tube 73 of the impregnation means 72a flows to the collective tube 73 of the impregnation means 72b and a part of the treatment fluid exits in the pressing zone 53 through openings of the supply lines 80 not shown in Fig. 6. Alternatively, the supply lines 80 of the impregnation means 72a and the supply lines 80 of the impregnations means 72b can be separated, so that through the impregnation means 72a another treatment fluid than through the treatment means 72b is introduced into the pressing zone 53. This enables a higher variability and adaptability of the treatment to be carried out by the press-roll arrangement 50 with various fibre masses and treatment fluids. The cross-section of the supply lines 80 is designed such that it essentially corresponds to the cross-section of the spaces 71 and thus largely fills the spaces 71. The flow S of the treatment fluid through the collective tube 73 is conducted through the supply lines 80 into the pressing zone 53. This can be in particular seen in Fig. 7, where a front view of the embodiment of Fig. 6 is shown in the moving direction B of the fibre mass 21. In Fig. 7, a supply line is shown as partial section in the region of the pressing zone, in particular in the region of the expansion region 55. The supply line comprises openings 81 in this region, through which the treatment fluid exits into the space 71 and enters the fibre mass 21 through the pressing surface area 52. Alternatively to the representation in Fig. 7, the section of the supply lines 80 facing the fibre mass 21 can also come into contact with the fibre mass 21. In this case, however, special arrangements with respect to the surface quality and the abrasion resistance of the supply lines 80 have to be taken in order to avoid a damage of the fibre mass 21 and a premature wear of the supply lines 80 by the fibre mass 21 being passed under pressure. In an alternative design of the embodiment of Figs. 6 and 7, the impregnation means 72a being in front with respect to the moving direction B of the fibre mass 21 can also be designed as a suction means by which treatment fluid is sucked off for example from the compression region via the openings 81 in the supply lines 80. In Fig. 7, furthermore a driving means 82, for example an electric motor, is represented, by which the press-roll 51 is rotatably driven synchronously with the motion of the fibre mass. Such a driving means 82 can also be used with other embodiments. In this design, the press-roll itself can be employed as conveyor means for the fibre mass 21, by which the fibre mass 21 is transported through the individual treatment steps of the pressing mill. Fig. 8 shows a fourth embodiment of a press-roll arrangement 50 according to the invention in a section in parallel to the moving direction B of the fibre mass 21 and perpendicular to the axial direction X of the press-roll 51. The press-roll arrangement 50 according to Fig. 8 comprises a counterpressure roll 90 which is pressed into the fibre mass 21 with a force of pressure F2 opposite to the press-roll's 51 force of pressure Fi having the same value. The press-roll 51 and the counterpressure roll 90 both comprise the same configuration which corresponds to the configuration of the first embodiment as represented in Figs. 2 and 3. For the sake of simplicity, for the embodiment of Fig. 8 therefore for elements, the construction and function of which correspond to previous embodiments, the same reference numerals are used. In the embodiment of Fig. 8, in the expansion region 54 the treatment fluid is sucked Off from the previous treatment step by the counterpressure roll 90, as schematically Shown by the arrow Si, while in the expansion region 55 treatment fluid for the next treatment step is conducted through the press-roll 52 into the fibre mass, as indicated by the arrow $2. Alternatively to this embodiment, each roll 51, 90 can effect a removal by suction as well as an impregnation in the pressing zone 53. As represented in Fig. 1 by means of the device 22, when using the press-roll arrangement 50 according to the invention in a pressing mill 22, the press-roll arrangement for the next treatment step can directly follow, as due to the impregnation of the fibre mass 21 through the pressing surface area 52, an immediate homogenous distribution of the treatment fluid in the fibre mass 21 is effected. Thereby, the overall length of the pressing and treatment device 22 is considerably reduced. Due to the immediate homogenous distribution within the fibre mass 21, which is supported by the short fibre distance in the expansion zone 55 and the resulting capillary effect, the impregnation process can be accomplished more precisely and be controlled more easily. As a result, even an impregnation with treatment fluids to be handled carefully, which possibly tend to react chemically, is possible. The rolls according to the invention can also be employed at other locations of a plant for manufacturing fibres, for example as draw-off rolls with integrated waxing means. Apart from the fibre mass of cellulose described by way of example, fibre masses of natural or synthetic fibres can also be treated by the device according to the invention and the method according to the invention, for example fibre masses of viscose, acetate, polyester, polyamide and polyacryl. Below, special examples for further illustrating the above-mentioned embodiments are given in a table. In the examples 1 to 4 of the following table, a fibre tow manufactured according to the Lyocell-method is brought into a staple shape by means of a wet cutting machine and in this condition applied on a treatment device 22 as fibre mass 21. Concerning the indications of weight, the fibre mass in an absolutely dry condition is taken as a basis. In example 5, the fibre tow is supplied to the treatment device 22 as fibre mass 21 directly without cutting it beforehand. As treatment fluid, water is used in all examples. The device 22 is in all examples 1 to 5 designed such that in every treatment zone the fibre mass 21 is completely penetrated by the treatment fluid across its whole thickness. in example 1, the impregnation of the fibre mass is effected according to the method from the prior art by spraying the treatment fluid onto the fibre mass in the conveying direction downstream of the press-roll. In this method, the fibre mass 21 is not completely penetrated immediately after the contact with the treatment fluid, so that the treatment fluid accumulates like a lake above the fibre mass and only gradually trickles through the fibre mass 21. This formation of a lake is increased as the thickness of the fibre mass is increased. A complete penetration of the fibre mass with the treatment fluid is only achieved after a relatively long dwell time of the fibre mass in the treatment zone. To this end, the treatment zone has to comprise a corresponding length in the conveying direction of the fibre mass through the treatment device. In example 2, the treatment is in contrast accomplished with a press-roll designed according to the invention with treatment conditions otherwise identical to example 1. As can be seen from the table when comparing examples 1 and 2, in example 1, i.e. the solution of the prior art, the fibre throughput per m2 of the treatment zone and per hour is considerably lower than in example 2. In the examples 3 to 5, the press-rolls according to the invention are also used, so that the fibre mass is immediately penetrated when contacted by the liquid and long treatment fields for the complete penetration of the fibre mass are not necessary. Moreover, in these embodiments an essentially more uniform and faster distribution of the treatment fluid in the fibre mass are the consequence.

Documents:

182-chenp-2004-abstract.pdf

182-chenp-2004-claims duplicate.pdf

182-chenp-2004-claims original.pdf

182-chenp-2004-correspondnece-others.pdf

182-chenp-2004-correspondnece-po.pdf

182-chenp-2004-description(complete) duplicate.pdf

182-chenp-2004-description(complete) original.pdf

182-chenp-2004-drawings.pdf

182-chenp-2004-form 1.pdf

182-chenp-2004-form 19.pdf

182-chenp-2004-form 26.pdf

182-chenp-2004-form 3.pdf

182-chenp-2004-form 5.pdf

182-chenp-2004-pct.pdf