WO2009006653A1

WO2009006653A1 - Apparatus and method for the treatment of a fibre composition

Info

Publication number: WO2009006653A1
Application number: PCT/AT2008/000228
Authority: WO
Inventors: Christoph Schrempf; Werner Richardt; Heidrun Fuchs; Rudolf Aigner; Helmut Fuchs
Original assignee: Lenzing Ag
Priority date: 2007-07-11
Filing date: 2008-06-25
Publication date: 2009-01-15
Also published as: EP2162577A1; BRPI0814222B1; EP2162577B1; TWI461584B; AT504649A4; CN101802286A; CN101802286B8; AT504649B1; TW200932984A; CN101802286B; BRPI0814222A2

Abstract

The invention relates to an apparatus for the treatment of a fibre composition with a treatment fluid composed of a distribution device for the treatment fluid with at least one pressure chamber, and also with a fibre transport device for the fibre composition, which is permeable to the treatment fluid. The invention further provides a method for the treatment of a fibre composition on a fibre transport device with a treatment fluid, where the treatment fluid is forced by superatmospheric pressure into the fibre composition.

Description

Apparatus and method for treating a pulp

The present invention relates to a device and a method for treating a fiber mass during its transport with a treatment fluid.

Fibers often have to be treated with fluid substances during their manufacture or further processing. These substances are generally liquids, vapors or gases needed for washing, bleaching, dyeing, impregnating, applying auxiliary agents such as finishes, sizings or surface finishes, as well as for intermediate treatments such as heating, drying or wetting. ,

The fibers are mainly artificial fibers based on celluloses, such as viscose, cellulose carbamate or lyocell fibers or synthetic polymers such as polyesters, polyolefins, aramids, polyimides, fluoropolymers and others. These fibers are usually cut, ie with a defined single fiber length. But the treatment of natural fibers such as cotton, wool, flax and other fibers of plant or animal origin is possible.

According to the invention, a large amount of these fibers is to be treated continuously at the same time. Widely used are methods in which a plurality of individual filaments, a so-called fiber cable, extruded from a spinneret and further cut into staple fibers. These staple fibers are floated to a nonwoven fabric. Comparable non-woven fabrics are formed in the course of processing of natural fibers such as wool or cotton. These can also be treated with the device according to the invention and the method according to the invention.

Known fiber treatment processes consist for example in that fiber cables are cut to the desired length, the fibers are floated to form a fiber fleece and deposited on a wire belt. A general description of the non-woven fabric washing can be found in Götze, "Man-made fibers by the viscose process", 1967, pages 881-884. The homogeneous non-woven is in

Countercurrent principle drizzled with a treatment liquid from above, sprayed or spilled. The treatment liquid penetrates by its own weight through the fleece through and washes the fleece out. In the fleece, a diffusion process takes place between the mobile fleet, which flows vertically in total, and the fleet immobilized in the fiber. At the end or between different washing fields, a desired nonwoven moisture can be adjusted by means of a pair of rollers. In order to achieve a better washout result, nonwoven fabric and washing liquid are usually passed in countercurrent. Such methods are also described, for example, in WO 00/18991, AT 413286 B and in AT 413285 B.

In principle, similar methods are also suitable for the impregnation of a nonwoven fabric. The homogeneous fiber fleece is drizzled with the impregnating solution, sprayed or poured and then pressed to the desired degree of moisture. This process can also take place in several sequences. During impregnation, for example, an emulsion or suspension can be applied to the fiber. An example of this is the so-called softening, wherein a lubricant is applied to the fiber. Avivages are excipients that are used, among other things, to give the fiber better processing properties. They are to improve, for example, the thread closure, the winding capacity and the handle, reduce the thread friction and impart antistatic properties. These lubricants are generally available as emulsions or suspensions.

To heat or damp a homogeneous nonwoven fabric, it may be sprayed from above and / or from below with steam or passed along steam heated convection radiant panels.

In all the methods described, it is disadvantageous that the treatment fluid is largely moved by gravity through the fleece. This is done relatively slowly, so that long treatment times and thus large apparatuses are required.

There has therefore been no lack of attempts to accelerate the movement of the treatment fluid through the nonwoven fabric. For example, so-called sieve belt filter presses are available, on which the fiber fleece is transported on a wire belt, wherein the fiber fleece is sprayed from above with treatment liquid. Below the screen belt, a suction chamber is attached, which moves along the distance of the washing field with the screen belt and sucks the liquid through the web and the wire through. Depending on the absorbency and structure of the nonwoven air is sucked in addition to the liquid and air, whereby the suction speed is reduced. In addition, which acts as a driving force for the movement of the treatment liquid through the nonwoven fabric Pressure difference limited to the vacuum power of the suction system. A treatment by means of gases or vapors is not possible with this device. Since the first time a negative pressure built up when attaching the suction chamber to the wire and at the end of the washing field, the vacuum must first be reduced to lift the suction chamber from the wire, additional residence time and thus equipment length is needed.

WO 03/004750 discloses a method in which a rotating press roll presses liquid initially contained from an incoming fiber mass in a compression zone by compacting the fiber mass and subsequently drawing in a treatment fluid during reexpansion of the fiber mass in an expansion zone. In this method, a high mechanical pressure must be applied by the press roll to densify the web. In addition, it has the disadvantage that rapid absorption of the treatment fluid is dependent on the suction effect of the nonwoven and thus, inter alia, on the expansion speed of the nonwoven. Another disadvantage is that only a comparatively small amount of treatment fluid can be sucked in. In WO 03/004750 it is also described that at the end of the compression zone treatment fluid can already be pressed into the compacted fiber fleece in order to rinse out a previous treatment fluid originating from the preceding treatment stage. Due to the fiber mass which is already highly compressed at this point, the possible backmixing into the preceding press-off operation and the sealing problem in the press roll, this embodiment appears rather disadvantageous. For the application of gaseous or vaporous treatment fluids, the method of WO 03/004750 is not suitable.

Compared to the known prior art, the object of the present invention was to provide a device and a method with which a fiber mass can be treated faster and more homogeneously with a treatment fluid in order to increase the quality and production capacity and to save as much as possible chemicals so that, for example, when converting an existing fiber treatment plant, the production capacity can be significantly increased or when building a new fiber treatment plant compared to a system according to the prior art lower investment and less space are needed. The solution to this problem is a device for treating a fiber mass (1) with a treatment fluid, comprising a distributor (2) for the treatment fluid with at least one pressure chamber (3) and a fiber transport device (4) for the fiber mass, which is permeable to the treatment fluid is, wherein the width of the entirety of all the pressure chambers is substantially equal to the intended width of the fiber mass on the fiber transport device.

For the purposes of describing the present invention, the terms "pulp" and "nonwoven" are used as synonymous. In it, the fibers are disordered.

The at least one pressure chamber is preferably open towards the fiber mass. For the purposes of the present invention, the fact that the pressure chamber is designed to open towards the pulp mass means that the side of the pressure chamber facing the pulp mass has no wall. In one possible embodiment, the pressure chamber may have a coarse-meshed grid on its open side in order to prevent the fiber mass from penetrating too far into the pressure chamber during treatment. Instead of the coarse-meshed grid, a perforated plate with large holes or a similar permeable partition can be used. When selecting it is always important that the treatment fluid thereby no large hydrodynamic resistance is opposed. However, such a grid is generally not necessary because the pressure of the treatment fluid usually prevents penetration.

In particular, in commercial fiber production plants, the fiber transport device and thus also the fiber mass to be treated several meters wide, generally between about 1 m and 4.6 m. The distributor is about 1 m long in the fiber transport direction. In order to achieve a rapid filling of the entire chamber volume and a uniform distribution of the treatment fluid over the entire surface of the distribution device in pressure chambers for such applications, it is advisable to subdivide the pressure chamber into a plurality of smaller pressure chambers and each with its own inlet for the treatment fluid It must be ensured that all pressure chambers are uniformly supplied with treatment fluid, so that the fiber mass is also uniformly treated everywhere.

The entry of the treatment fluid into a pressure chamber can be done by a simple, usually centrally located in the top opening (5). Because the fluid is too fast Filling the pressure chamber usually flows at a higher speed, a device is preferably attached to the inlet, with which the fluid can be distributed within the pressure chamber. Such a device may for example be a baffle plate. Likewise, annular or other distribution systems are possible. They are intended to prevent the fluid from hitting the batt directly at high speed and changing its structure, for example by creating pits.

The required chamber size and the clear height depend strongly on the product type and on the homogeneity of the nonwoven. Inhomogeneous nonwovens require a smaller area of the single chamber. Wet-rigid nonwovens swell up more and require larger chamber height. On the one hand, the pressure chamber should be able to be filled quickly, so it must not have too much volume. On the other hand, the chamber must not be so flat that it is completely filled by the swelling fiber mass. For cellulosic fibers a clear height of the pressure chamber of about 1 - 5 cm is best. The area of a single pressure chamber can be between 100 and 40,000 cm ² .

The distribution device generates a surface pressure on the nonwoven fabric by means of the treatment fluid. In conventional types of treatment, such as washing or impregnation with aqueous liquids, the overpressure of the treatment fluid in the pressure chamber is usually between 0.2 and 1 bar. When treated with .Heißdampf, for example, for steaming or steam heating sets over the nonwoven the vapor pressure, which corresponds to the balance between nonwoven resistance, tightness of the pressure chamber and the amount of steam supplied. For example, in experiments according to the invention, the pressure chamber was supplied with a 15 bar steam. In this case, between 62 and 1250 kg of steam were injected per m ² . About the fleece while a temperature of max. 131 ⁰ C measured. This corresponds to an overpressure of 1.7 bar. Due to the resulting pressure gradient across the fleece height, the treatment fluid is pressed into and through the fleece. This initially leads to a filling of the nonwoven pores and subsequently to a swelling of the nonwoven fabric and to a rapid replacement, pressing through, washing or steaming the fiber mass in the pressure-reducing direction through the treatment medium. Due to the strong swelling of the web, the access of the treatment fluid to all fibers is surprisingly greatly facilitated. It has surprisingly been found that this larger quantities of liquor are possible and thus washing, impregnation and Bedämpfungsvorgänge are extremely accelerated. In experiments, three to fourfold quantities of liquor could be achieved without problems compared to the known in the prior art Anfäufelungsverfahren. Even thicker nonwoven layers are possible, which increase the production capacity of a also considerably increase existing facilities. Due to the rapid complete replacement of the treatment fluid in the web, the desired equilibrium state is reached more quickly in chemical and physical processes, so that the production speed is limited only by the pure reaction times or diffusion times. The residence time in a treatment field can be in conventional cases about 10 to 70 s, preferably even only 15 to 40 s. The ratio of the flow rate (expressed as mass) of the treatment fluid to the mass of the nonwoven may be referred to as the liquor ratio. This liquor ratio depends on the pressure of the treatment fluid, the thickness and swelling behavior of the web, and other factors. It can, in particular, when the treatment fluid is a liquid, easily flow rates can be achieved, which correspond to 40 times and more of the mass of the web, so liquor ratios of 40 and more. Also liquor ratios of more than 100 are conceivable with appropriate pressure of the treatment fluid.

Depending on the application, however, the device according to the invention and the method according to the invention, in particular if the treatment fluid is a gas or vapor, are also suitable for very low liquor ratios. Due to the homogeneous, rapid distribution of the treatment fluid in the pulp in these cases, often only liquor ratios of less than 2.0 and in particular less than 1, 0 be necessary to achieve the desired effect.

Likewise, the uniformity of the distribution of the treatment fluid between upper, middle and lower layers of the web is significantly improved.

A preferred embodiment of the device according to the invention is that the distributor is movable parallel to the direction of movement of the fiber mass and vertical to the direction of movement of the fiber mass (Figure 1). As a result, the distribution device can be moved to the current fiber transport device at a predetermined

Place are placed (step (A)) and is guided for a defined time with the fiber mass (steps (B) to (C)). During this time, the treatment of the fiber mass with the treatment fluid is carried out by treatment fluid is passed through a supply line in the distribution device. In general, the treatment fluid is passed under pressure into the distributor. Subsequently, the distributor is lifted at a likewise predetermined point of the fiber transport device (step (Q)) and returned at a distance from the fiber mass back to the Aufsetzstelle. In this case, the distributor must be moved so that in the cycle which has now begun, it treats the surface of the fiber fleece which lies exactly behind the surface which was treated in the preceding cycle. The distribution device can also be designed so that it has several units of pressure chambers and that these units can be moved independently. These units may be arranged side by side so that a strip of the nonwoven fabric can be treated with the pressure chambers of each unit. In this case, a unit can be moved on the fiber fleece, while a unit arranged next to it is being lifted. Such a plurality of units is conceivable, in particular, when the nonwoven to be treated is so wide that a single unit would be so large and heavy that it would have mechanical disadvantages compared with a number of smaller units.

Since the treatment fluid is preferably to be passed under pressure through the fiber mass, a preferred embodiment of the device according to the invention is designed so that the pressure chamber can be brought so close to the fiber transport device that the side walls of the pressure chamber touch the fiber threads. However, it is not intended according to the invention that by placing the distributor the fiber mass is strongly compressed, as z. B. happens at a press roll. By such compression, the fiber mass would be strongly compressed, so that the treatment fluid could no longer flow unhindered and fast enough through the fiber mass and thus rather prolongs the treatment time or the treatment result, such as washing out, would be worsened.

However, it must be expected that certain fibers swell when treated with certain fluids and therefore anyway exert a back pressure on the distributor. Such a strong swelling occurs, for example, when treating cellulosic fibers such as viscose or lyocell with aqueous media, while no significant swelling of the nonwoven fabric is observed when treating polyester fibers with water. This must be taken into account, for example, in the design of the mechanical guidance of the distributor.

The side walls of the pressure chamber should preferably be designed so that they seal the pressure chamber from the atmosphere upon contact with the fiber mass. For this purpose, it is generally sufficient that these side walls have a closed, round running, lower flat surface or edge (6). This sealing surface or edge, which is placed on the fiber mass, may additionally be profiled, for example. Additional elastic sealing materials are generally not necessary because the pulp itself, which is mostly swollen, is the elastic counterpart. It is not necessary to prevent any escape of treatment fluid. This would only be possible by strong pressing the pressure chamber on the pulp, but what not wanted. The small amounts of laterally exiting treatment fluids can be easily detected by the anyway necessary collection system with.

In order for the screen belt, on which the fiber mass is transported, to withstand the applied pressure, which can easily amount to several tons despite the relatively low pressure of the treatment fluid, it must be supported from below. Most suitable for this purpose is a support plate (7) on which slides the screen belt along. This support plate is preferably provided continuously and at defined locations with drainage openings (8), which allow the outflow of the treatment fluid. In segments without drainage openings, the treatment fluid can not flow away, so that a longer treatment time is achieved there. Instead of openings in a long support plate and open spaces between shorter support plates can allow the flow of treatment fluid from the pulp and the wire belt.

A further preferred embodiment of the device according to the invention (Figure 2) has a stationary pressure chamber and in addition an upper wire (9), with which the fiber mass can be covered and which is moved at substantially the same speed as the fiber mass, wherein the open side of the Pressure chamber the upper side of the upper screen belt touched directly. The seal between the pressure chamber and the upper screen belt takes place according to basically known principles. For example, the principle of a sliding sealing surface which is preferably friction and wear resistant, can be applied. In the edge region, the screen belt as a dense belt, d. H. without drainage holes, designed to optimize the sealing surface. When sealing, the swelling of the fleece must be taken into account. Thus, for example, the seals may be stored soft, so that the treated web can swell during treatment. In this embodiment, a juxtaposition of multiple treatment cycles is particularly simple and space-saving possible.

This embodiment also preferably has the support plates (7) already described above.

As a fiber transport device or screen belt for both embodiments are all suitable to those skilled appear devices, in particular straps, belts, link chains ("tank chain"), fleece tapes, knitted or woven tapes made of metals, plastics, plastic-coated metals or the like in question • Perforations, such as fabric-reinforced rubber bands, may be appropriate depending on the application.

The invention also provides a process for treating a fiber mass (1) on a fiber transport device (4) with a treatment fluid, in which the treatment fluid is pressed into the fiber mass with overpressure. Preferably, the treatment fluid is a liquid, an emulsion, a suspension or a vapor. Preferably, the treatment fluid is pressed into the fiber mass via a pressure chamber (3).

In a preferred embodiment of the method according to the invention, the pressure chamber, which is designed to be open towards the fiber mass, is placed on the fiber mass (A) at the beginning of the treatment time, while the treatment time is moved at substantially the same speed as the fiber mass in the fiber transport direction (B) - ( C), lifted at the end of the treatment time of the fiber mass (D) and placed again on a not yet treated portion of the fiber mass.

In a further preferred embodiment of the method according to the invention, the fiber mass is transported by an upper sieve belt (9) under the stationary pressure chamber (3) along, with the open side of the pressure chamber directly touching the upper sieve belt.

In both embodiments, the fiber transport device or the wire belt corresponds to that already described for the device according to the invention. The pulp is preferably a staple fiber fleece.

Examples:

In the following the invention will be explained by means of examples. However, the invention is not limited to the scope of the examples. In the examples with the device according to the invention, the method according to the invention is always carried out.

Example 1 (Comparative): On a prior art fiber treatment apparatus with dribbling from above, a fleece of lyocell staple fiber was sprinkled with aqueous sodium hydroxide solution. At the end of the treatment field, the sodium hydroxide content was determined in each case in the liquor and in the fiber in different layers of the nonwoven by sampling and subsequent titration. Table 1 shows the deviations from the nominal value. Example 2 (invention):

On a fiber treatment device according to the invention, which had a entrained pressure chamber according to the first embodiment described above, a fleece made of lyocell staple fiber was treated with aqueous sodium hydroxide solution. Also at the end of this treatment field, the sodium hydroxide content was determined in each case in the liquor and in the fiber in different layers of the nonwoven by sampling and subsequent titration. Table 1 shows the deviations from the average value.

Table 1: Deviation of the NaOH content from the average value in [%]

Example 3 (Comparison) and Examples 4 to 6 (invention): On a fiber treatment device according to the prior art as in Example 1 or according to the present invention as in Example 2, a Lyocell Stapelfaservlies having a weight per unit area of 6 kg / m ² first pressed with a press roller and then treated with fresh water. Table 2 shows the treatment time required in each case, which is substantially shorter than in accordance with Example 3 according to the prior art, despite in some cases considerably higher wash liquid throughputs in the device according to the invention of Examples 4 to 6.

Table 2: Treatment time with liquid

Example 7 (comparison): On a fiber treatment device according to the prior art with spray bar at the top and bottom of the fleece, with which this was sprayed with saturated steam, a Lyocell staple fiber fleece with a weight of 6 kg / m ^{2 was} first pressed with - a press roll and then with saturated steam treated.

Example 8 (invention):

On a fiber treatment device according to the present invention as in Example 1, a Lyocell staple fiber nonwoven fabric having a basis weight of 6 kg / m ^{2 was} first pressed with a press roll and then treated with saturated steam.

After the press roll, the nonwoven fabric had the same temperature and moisture content in both examples. Table 3 shows the treatment times that were needed to heat the fleece uniformly around 85 ^° C. everywhere. With the device according to the invention of Example 8, this succeeded in a much shorter time than in Example 7 according to the prior art. Nevertheless, in the device according to the invention considerably less steam, based on the amount of fiber was required than in the device according to the prior art.

Table 3: treatment time with saturated steam

Claims

Claims:

1. A device for treating a fiber mass (1) with a treatment fluid consisting of

• a distribution device (2) for the treatment fluid with at least one

Pressure chamber (3) and • a fiber transport device (4) for the fiber mass, which for the

Treatment fluid is permeable, characterized in that the width of the totality of all the pressure chambers substantially the intended for the fiber mass width on the

Fiber transport device corresponds.

2. Device according to claim 1, characterized in that the at least one pressure chamber is designed to be open towards the fiber mass.

3. A device according to claim 1, wherein the distribution device parallel to the direction of movement of the fiber mass and vertical to the direction of movement of the

Fiber mass is movable.

4. Apparatus according to claim 3, wherein the pressure chamber can be brought so close to the fiber transport device that the side walls of the pressure chamber touch the fiber mass.

5. Apparatus according to claim 4, wherein the side walls are configured to seal the pressure chamber from the atmosphere upon contact with the fiber mass.

6. The device according to claim 2, in which the pressure chamber is stationary and which additionally has an upper screen belt (9), with which the fiber mass can be covered and at substantially the same speed as the

Fiber mass is moved, the open side of the pressure chamber directly touches the upper wire belt.

7. The device according to claim 1, wherein the fiber transport device is a belt, a screen belt, a belt strap, a link chain, a fleece, a knit, a fabric or a continuous, perforated conveyor belt.

8. A method for treating a fiber mass on a

Fiber transport device with a treatment fluid, characterized in that the treatment fluid is pressed with overpressure in the fiber mass.

9. The method according to claim 8, wherein the treatment fluid over a

Pressure chamber is pressed into the pulp.

A method according to claim 8, wherein the treatment fluid is a liquid, an emulsion, a suspension, a gas or a vapor.

11. The method according to claim 8, wherein the pressure chamber is pressed onto the fiber mass at the beginning of the treatment time, during the

Treatment time at substantially the same speed as the fiber mass is moved in the fiber transport direction, is lifted at the end of the treatment time of the fiber mass and placed again on a not yet treated portion of the fiber mass.

12. The method according to claim 8, wherein the fiber mass of an upper

Covering belt is covered and transported under the stationary pressure chamber along and wherein the open side of the pressure chamber directly touches the upper wire belt.

13. The method according to claim 8, wherein the fiber transport device is a screen belt.

14. The method of claim 8, wherein the pulp is a staple fiber fleece.