DE102005027349A1 - Post-treatment of cellulose fibres for use in textile production, especially to reduce fibrillation, involves crosslinking with glutaraldehyde and removing residual unreacted aldehyde by treatment with sodium bisulfite - Google Patents

Abstract

A method for the post-treatment of cellulose fibres (especially Lyocell fibres) to reduce the tendency to fibrillation by treatment with a crosslinking agent containing at least two carbonyl groups, in which free unreacted crosslinker is removed by treatment with a bisulfite compound. A method for the further treatment of cellulose fibres, especially for lowering the fibrillation tendency of lyocell fibres and filaments, involves (a) contacting the fibres with a crosslinking agent (I) containing at least two functional groups which undergo chemical reaction with cellulose (preferably carbonyl groups) and then (b) reacting any free unreacted (I) with a bisulfite compound. Independent claims are also included for (1) apparatus for the above process, with a first treatment stage for application of (I) followed by a washing solution and a second stage for treatment with bisulfite solution (2) cellulose fibres or filaments obtained by this method and containing less than 150 mg crosslinking agent/kg fibre.

Description

The The invention relates to a process for the post-treatment of cellulose fibers, in particular for reducing the fibrillation tendency of lyocell fibers and filaments, wherein in a first post-treatment phase a Crosslinking agent having at least two functional groups, the react chemically with cellulose, preferably carbonyl groups, is brought into contact with the cellulose fibers and by this Method produced cellulose fibers or filaments.

The The invention further relates to a device for the after-treatment of Cellulose fibers having a first stage of treatment with a cellulose-crosslinking Crosslinking agent and a washing device for the treatment of crosslinked cellulose fibers with a washing solution.

Cellulose fibers When wet, they usually have textile-physical characteristics depending on the characteristics in the dry state of the fibers differ. The term "fiber" is used in this application as a length-independent generic term for all textile fibers, such as filaments, which is a very large, practical endless length have, and length-limited Staple fibers spun into spun yarns. Furthermore, the terms "fibers" and "threads" are used synonymously below.

Especially Solvent-spun Fibers, such as lyocell fibers, exhibit mechanical when wet Stress, for example by scrubbing, tends to fibrillate on. Fibrillation is the breaking up of the wet fibers in longitudinal direction understood, giving the fiber a hairy, furry appearance, as described in WO 97/49856.

Around the tendency to fibrillation, in the following also fibrillation tendency called counteract, are numerous from the prior art approaches known in which the fibrils running parallel in the fiber Cellulose chains are cross-linked to the Fibrillierungsneigung to reduce.

In the EP 0 785 304 A2 there is disclosed a method for reducing the tendency of fibrillating solvent-spun cellulose fibers to fibrillate, in which a chemical reagent having two to six functional groups which react with cellulose under alkaline conditions is added to an aqueous system of never-dried, solvent-spun cellulose. In the method of this document, a polyazine ring having reactive halogen atoms is preferably used as functional groups, for example, a trichloropyrimidinyl compound.

Also in WO 97/49856, Lyocell fibers are treated with a textile treatment agent based on a triply substituted 1,3,5-triazine or its used alkaline salt.

However, the reduced tendency to fibrillation, which occurs with the method of EP 0 785 304 A2 or WO 97/49856 is lost again because halogenated polyazines with cellulose form ether groups which are hydrolyzed by scrubbing and washing, as mentioned in WO 95/28516. In WO 95/28516, therefore, a method is described in which Lyocell fibers are treated under alkaline conditions at elevated temperature with a chemical reagent having on average at least 2.1 acrylamido groups per molecule. Following crosslinking, the lyocell fibers are washed and dried.

Because the alkaline medium of pH 11 to 14 of the crosslinking reaction of WO95 / 28516 leads to hydrolysis of the active acrylamido group the crosslinking reagent only shortly before the reaction with the cellulose fibers be added. Therefore, especially long storage times or a long reaction time of the chemical reagent of WO 95/28516 problematic.

In the DE 100 48 681 A1 , which is considered to be the closest prior art, describes the treatment of cellulosic shaped bodies with an aqueous aldehyde solution in order to increase the wet modulus of cellulose shaped bodies. The process of this document initially comprises a crosslinking of the cellulose shaped bodies. For this purpose, the moldings are treated with an aqueous aldehyde solution, the treated fibers are then fixed with a catalyst, for example an acidic metal salt, and finally crosslinked at elevated temperatures in a condensation reaction.

Preferred aldehyde solutions according to this document are C ₃ -C ₇ -dialdehydes, such as glutaric dialdehyde. The networking process is followed by the DE 100 48 681 A1 a washing step for removing the non-fixed residues of the treatment liquid.

In the process of DE 100 48 681 A1 As with the other known from the prior art method for crosslinking of cellulose fibers, the problem arises that residues of the crosslinking agent, which did not react chemically with the cellulose fiber, can not be washed out by the cellulose fibers, and therefore remain in the crosslinked fibers. This is problematic both for the possible applications of the fibers as materials for clothing as well as with respect to the fiber properties.

Of the Invention is therefore the object of the application crosslinked cellulose fibers and to broaden the properties in particular the textile-physical properties of the post-treated Cellulose fibers, as with the known methods for aftertreatment made of cellulose fibers can be improved.

These Task is for the method mentioned in the present invention achieved in that free cross-linking agent in a second post-treatment phase, which in the first post-treatment phase not chemically with cellulose reacted, is reacted chemically with a bisulfite compound.

For the input said device achieves this object by a second treatment stage with a bisulfite solution for the chemical reaction of the crosslinking agent dissolved.

Surprisingly, the level of free crosslinking agent which has not chemically reacted with the cellulose fibrils of the fibers can be lowered in the cellulosic fibers by a simple chemical reaction with a bisulfite compound. The chemical reaction takes place in a very rapid reaction at room temperature, using a cost-effective bisulfite reagent. Unlike washing according to the procedure of DE 100 48 681 A1 allows the additional implementation of bisulfite a significant reduction in the content of crosslinking agent in the cellulose fiber, which surprisingly fibrillierungsneigung, other textile-physical sizes of the fiber improve and widens the range of application of the fibers, in particular for the production of clothing.

So can be in the produced by the method according to the invention Cellulose fibers or filaments less than 150 mg of crosslinking agent per kg Cellulose fiber prove. With the method according to the invention can be even Cellulose fibers containing less than 75 g, preferably 10 mg to 30 mg of crosslinking agent per kilogram of fiber. The wet abrasion number, a parameter for characterization the Fibrillierungsneigung of fibers, the inventively produced Cellulose fibers, is at least 300, preferably at least 400th

The thus improved methods of aftertreatment can be achieved by various independent from each other and for each advantageous embodiments, which combines arbitrarily with each other can be be developed further.

In In a particularly advantageous embodiment, a dialdehyde as Crosslinking agent used. Unlike the keto group is an aldehyde with its primary Carbonyl group much more reactive. The higher reactivity of aldehydes leads to a favorable, shortened Treatment time in both the crosslinking of the cellulose fibers in the first Post-treatment phase as well as in the chemical implementation of the second Post-treatment process.

Suitable crosslinking dialdehydes according to the invention C ₂ -C ₈ dialdehydes. When choosing the dialdehyde as a crosslinking agent, the length of the carbon chain must be considered. The chain length influences both the water solubility of the dialdehyde, which decreases with longer carbon chains, and the ability of the dialdehyde to form crosslinks between two cellulose fibrils. Here, glutaraldehyde (1.5 pentanedial, also called glutaraldehyde) has been found to be a particularly advantageous compound, because glutaraldehyde has a good water solubility on the one hand and a sufficient C chain length for effective crosslinking of the crosslinked cellulose fibrils without negative steric constraints.

According to a further advantageous embodiment of the method according to the invention, sodium bisulfite can be used as the bisulfite compound to the chemical crosslinking agent, such as a dialdehyde such as glutaraldehyde, the free crosslinking agent. Sodium bisulfite is a good water-soluble, inexpensive salt, which reacts very rapidly with a carbonyl group in a nucleophilic addition.

Further It has proved to be particularly advantageous if a Bisulfite ion concentration of 0.38 g / l to 16 g / l, preferably a concentration of 0.75 g / l to 8 g / l and especially in one Concentration of between 3.0 g / l and 4.7 g / l is used. When using sodium bisulfite, thus resulting in advantageous Concentration ranges from 0.5 g / l to 20 g / l, preferably from 1 g / l to 10 g / l and more preferably from 4 g / l to 6 g / l.

It let yourself in principle, the tendency to determine that the content of the free Crosslinking agent in the fibers with increasing concentration of Bisulfite compound decreases. However, at too high bisulfite concentrations a slight decrease in wet scrub to watch what's up a decrease in crosslinking efficiency at too high bisulfite concentrations indicated. Especially in concentration ranges of Bisulfitionen from 0.75 g / l to 8 g / l and especially in the range between 3.0 g / l and 4.7 g / l can be an effective reaction of the free crosslinking agent can be achieved without reducing the wet scrub number.

Also the pH at which the chemical reaction of the free cross-linking agent due to the bisulfite compound has an impact on the chemical reaction of the free crosslinking agent. According to one further advantageous embodiment the method according to the invention may be the chemical reaction of the crosslinking agent at pH 4.0 to 10.0, preferably at pH 4.5 to 6.0. Tends to decrease the content of the free cross-linker in the fiber with increasing pH values.

Further can according to a further advantageous embodiment the method according to the invention Cellulose fiber in the second treatment phase before the chemical Reaction of the free crosslinking agent washed at least once become. By this simple measure can be surprisingly the Vernetzerkon concentration in the cellulose fibers in comparison to a process without prewash decrease significantly.

in the The invention is based on an embodiment and on the basis of test results and experimental examples with reference to the drawings. The different features of the individual embodiments can thereby independently can be combined or omitted from each other, as stated above the individual advantageous embodiments has already been set forth.

It demonstrate:

1 a schematic overview of a plant for post-treatment of lyocell fibers;

2 a schematic representation of another embodiment of the plant for post-treatment of lyocell fibers;

3 the content of glutaric dialdehyde in the lyocell fiber as a function of the concentration of sodium bisulfite used; and

4 the content of glutaric dialdehyde in the lyocell fiber as a function of the pH during the chemical reaction of glutaric dialdehyde with sodium bisulfite.

First, the sequence of the process for the post-treatment of the lyocell fibers and an embodiment of the device based on the 1 described.

A plant for producing cellulosic shaped bodies, such as continuous fibers, from an extrusion solution which contains cellulose, water and a tertiary amine oxide, for example N-methylmorpholine-N-oxide (NMMO), is known in 1 for the sake of clarity not shown. Such systems are known in the art, for example DE 101 32 214 A1 known.

In an in 1 only schematically illustrated system is a cellulosic continuous molding, such as never-dried spun-moist lyocell filaments of a cutting machine 2 fed.

In the cutting machine 2 there is a pair of rollers 3 for the supply of cellulose threads 1 to the cutting apparatus 4 , which is also part of the cutting machine 2 is. The cutting apparatus 4 pulls that from the take-off roller pair 2 supplied filament 1 to horizontally rotating cutting blades, through which the pulp is cut to a predetermined length. During the cutting process water is supplied, so that a substantially mat-shaped fiber mass 5 from the cutting machine 2 exit and into a device 6 for post-treatment of the cellulose fiber mass 5 is swept or encouraged.

The device 6 for the aftertreatment of the pulp 5 as well as in the device 6 performed process for the aftertreatment of the pulp 5 as nonwoven or cellulose filaments essentially form the subject of the present invention.

In the aftertreatment device 6 run the cellulose threads in a conveying or transporting direction T first through a first post-treatment zone 7 in which an impregnation with crosslinking agent and the crosslinking of the cellulose threads 5 is carried out. After that, the pulp becomes 5 in a first fleece opener 30 opened and even a second treatment step 8th given up. In the second post-treatment zone 8th finds a chemical reaction from the first aftertreatment step 7 leaking and in the fleece opener 30 open fibers 5 instead, leaving free crosslinking agent 10 that does not match the cellulose fibers 5 has reacted from the fiber mass 5 Will get removed. Following the second post-treatment stage 8th becomes the pulp 5 , For example, a nonwoven fabric 5 , into a second fleece opener 28 Open and as a even fleece a belt dryer 29 fed. In the belt dryer 29 the drying of the fibers takes place 5 to the desired final moisture. Instead of a belt dryer 29 It is also possible to use a perforated drum dryer or any other drying device.

The mat-shaped pulp 5 is by means of a transport device 9 in a transport or conveying direction T first through the first post-treatment zone 7 , then closing through the second aftertreatment zone 8th and finally through a dryer 29 emotional. The conveyor 9 For example, may be a conveyor belt, which is the pulp 5 transported through the treatment tank of the individual treatment zones, or a flat conveyor channel, in which the fiber mass 5 transported by the treatment fluids of the respective aftertreatment stages.

In the first post-treatment zone 7 become the fibers 5 with a crosslinking agent 10 contacted and crosslinked to reduce the fibrillation tendency. The treatment time of the cellulose 5 with the crosslinking agent 10 is 1 to 4 minutes. The crosslinking agent 10 may for example be an aqueous solution with 23 g / l glutaric dialdehyde containing 30 g / l MgCl ₂ .6 H ₂ O as a catalyst for the preferably occurring at elevated temperature crosslinking reaction, also called fixation contains. The first post-treatment zone 7 ends with a first press roll arrangement 11 , The first press roller arrangement 11 can either, as in 1 shown, as a pair of rollers or as a single roller with a fixed counter-pressure surface be formed.

By the press roller assembly 11 applied pressing pressure is the in the first post-treatment zone 7 introduced crosslinking agents 10 , For example, glutaric dialdehyde, pressed from the pulp and in a collection container 12 which is below the first press roll arrangement 11 is arranged, collected.

To the consumption of the glutaraldehyde solution 10 to minimize that will be out of the pulp 5 Pressed solution from the collecting container 12 recirculated and again the first aftertreatment zone 7 fed. Possible losses of the crosslinking agent 10 need fresh crosslinking agent 10 be supplemented.

The from the first post-treatment zone 7 exiting, at least partially crosslinked fiber mass 5 is through the transport device 9 to a first fleece opener 30 which is the pressed fiber 5 opens and evenly distributed, promoted and then the second post-treatment zone 8th fed. In this second treatment zone 8th takes place in the transport direction T successively prewash, a chemical reaction and a final wash of the crosslinked fibers 5 instead of.

The chemical conversion of the fibers 5 lasts about 1 to 4 minutes and the pre-wash or the final wash is usually done within 3 to 12 minutes.

In each of the three treatment zones - prewash 13 . 13a . 13b , Implementation 14 and lingerie 15 - the second post-treatment zone 8th find treatment steps or phases to remove the glutaral dehyds from the pulp 5 instead of. The individual partial wash areas 13 . 13a . 13b . 14 and 15 the second aftertreatment zone of 1 are essentially analogous to the first post-treatment zone 7 of the 1 built up. For all subzones 13 . 13a . 13b . 14 and 15 the second post-treatment phase 8th becomes a treatment fluid 16 . 16a . 16b . 16c respectively. 17 with the pulp 5 brought into contact or the pulp 5 is from this treatment liquid 16 . 16a . 16b . 16c respectively. 17 durchtränk. During the transport of the pulp 5 through the individual zones 13 . 13a . 13b . 14 and 15 the treatment fluid acts on the cellulose fibers 5 one and each subarea 13 . 13a . 13b . 14 and 15 ends with a roller arrangement 18 . 19 . 20 . 21 respectively. 22 containing the treatment fluid 16 . 16a . 16b . 16c respectively. 17 from the fibers 5 pressed and which the different subzones 13 . 13a . 13b . 14 and 15 the second post-treatment zone 8th delimited in the transport direction T from each other.

In the prewash area 13 to 13b become the cross-linked cellulose fibers 5 first with water as a pre-wash 16 . 16a . 16b , preferably with demineralized or distilled water 16 washed. Although the prewash zone 13 to 13b in the 1 Of course, the apparatus according to the invention is not limited to a three-stage prewash, but can provide any number of washing stages. Also, the prewash is 16 . 16a . 16b not limited to water. Rather, any suitable for washing the fibers fluid as a cleaning fluid 16 be used. It is also not necessary in every prewash zone 13 . 13a . 13b the same detergent 16 to use.

At the end of each of the three prewash stages 13 . 13a and 13b becomes the washing water 16 . 16a . 16b through a pair of rollers 18 . 19 respectively. 20 from the fiber mass 5 pressed and in a collecting device 23 . 24 respectively. 25 collected. In contrast to the first post-treatment stage 7 of the 1 becomes the treatment fluid 16 . 16a . 16b from each of the pre-wash stages 13 . 13a and 13b dissipated, so not reused to the water 16 dissolved part of the crosslinking agent 10 removed from the system. Of course, the washing liquid can 16 each of the pre-wash stages 13 to 13b also be performed in circulation or in countercurrent and / or in cascade mode. However, then a cleaning of the liquid should be done to prevent any waste in the fluid 16 accumulate.

At the last pre-wash stage 13b closes in the transport direction T, the chemical modification zone 14 the second post-treatment zone 8th at. In the chemical modification area 14 , also reaction or inactivation zone 14 called, becomes a chemical reaction fluid 17 with the pulp 5 brought into contact. The chemical conversion solution 17 contains a bisulfite compound, preferably sodium hydrogen sulfite in a concentration range of 0.5 g / l to 20 g / l, preferably concentrations of 1 g / l to 10 g / l, particularly advantageously in the concentration range of 4 g / l to 6 g / l.

In the inactivation zone 14 finds a chemical reaction of the free cross-linking agent 10 which does not interfere with the cellulose fibrils of the pulp 5 has reacted instead. The reactive carbonyl group of the glutaric dialdehyde reacts in a nucleophilic addition with the bisulfite of sodium bisulfite.

The chemical substitution of the crosslinking agent is necessary because a washing of the crosslinked pulp 5 with water is insufficient to the content of free, in the fiber 5 existing glutaric dialdehyde to the desired level of less than 150 mg, preferably less than 75 mg and in particular to 10 mg to 30 mg per kg of fiber. A reduction of glutaraldehyde which, although in the pulp 5 is included, but has not reacted cross-linking with the cellulose fibrils, is only possible after the free glutaric dialdehyde has been chemically reacted with bisulfite.

The zone of chemical conversion 17 ends with a pair of rollers 21 which is the chemical reaction fluid 17 from the sulfite-washed pulp 5 squeezes. The pressed-off bisulfite solution 17 is in a catcher 26 collected, recycled and again in the chemical washing area 14 the second post-treatment zone 8th used.

The second post-treatment zone 8th finally ends with a final laundry section 15 which is essentially one of the pre-wash stages 13 . 13a respectively. 13b equivalent. When the final wash is again water 16 added as a treatment fluid to the residues of the chemical reaction fluid 17 and in the inactivation zone 17 resulting glutaraldehyde bisulfite complex from the pulp 5 wash out.

After the roller pair 22 the final wash step 15 the washing fluid 16e from the cellulose pulp 5 Pressed, the cross-linked and bisulfite treated staple fibers from the second post-treatment zone 8th and again in another fleece opener 28 open and then evenly a belt dryer 29 supplied in which the desired final moisture content of the post-treated fibers 5 is set.

In the final washing zone 15 the second post-treatment zone 8th may be the pH of the treatment fluid 16 by adding sodium hydroxide to the pH of the pulp 5 for subsequent post-treatment, other treatments, such as adjusting a finish.

Likewise, the pH of the in the reaction zone 14 added treatment fluid 17 adjusted to pH values that are particularly well suited for a chemical reaction of the crosslinking agent with sodium bisulfite. Thus, the reaction fluid 17 be adjusted for example with sodium hydroxide to a pH of 4 to 10, preferably to a value of 4.5 to 6.

2 shows a schematic representation of another embodiment of the aftertreatment device 6 , In the following, only the differences from the execution of the 1 received. For elements whose structure and / or function substantially correspond to elements of the preceding embodiment, the same reference numerals are used.

In 2 are obtained from NMMO-liberated lyocell fibers with a crosslinking agent 10 containing glutaric dialdehyde as cross-linking agent and a catalyst, for example magnesium chloride. On the sprinkler 31 initially follows a low-pressure pressing plant 32 and then a high pressure press shop 33 which the excess crosslinking liquid 10 from the fiber mass 5 Press off. The illustrated press shops 32 respectively. 33 of the 2 are shown as press roller pairs, but it can be used in principle any type of press shop.

The pressed fiber fleece 5 is then in a first fleece opener 34 opened and evenly a sieve drum dryer 35 fed.

In the sieve drum dryer 35 the fixation of the cross-linking agent takes place 10 on the fiber. The fixation is carried out over a certain period of time, for example for 10 minutes, at an elevated temperature of for example 100 ° C. Alternatively to a perforated drum dryer 35 It is also possible to use a belt dryer, a damper or any other heating device.

After emerging from the sieve drum dryer 35 become the cross-linked fibers 5 in a second fleece opener 36 which is the first fleece opener 34 corresponds, reopened and the second aftertreatment zone 8th evenly fed. Alternatively, a fleece opener with subsequent flooding of the fibers can be used.

For the sake of clarity, the second post-treatment stage 8th of the 2 from the field of prewash 13 until the chemical reaction with bisulfite 14 only as a box 8a indicated. The structure corresponds essentially to the levels of 1 ,

In the second treatment zone 8th takes a chemical reaction from that of the first aftertreatment step 7 leaking and in the fleece opener 30 open fiber 5 instead, leaving free crosslinking agent 10 that did not react with the cellulosic fibers, from the pulp 5 Will get removed. On the final washing zone 15 of the 2 initially follows a low-pressure pressing plant 22a and then a high pressure press shop 22b which the excess washing liquid 16c Press off from the pulp. The illustrated press shops 22a respectively. 22b of the 1 are shown as pairs of rollers, but it can be used in principle any type of press shop.

After the roller pair 22b the final wash step 15 the washing fluid 16c from the cellulose pulp 5 Pressed, enter the crosslinked and bisulfite treated staple fibers of the 2 from the second aftertreatment zone 8th and become another post-treatment step 37 who fed to Avivage. On the lubrication zone 37 again followed by a low-pressure press shop 38 and then a high pressure press shop 39 which the excess avivage medium 40 from the fiber mass 5 Press off. Also the illustrated press shops 38 respectively. 39 of the 2 are exemplified as roller pairs.

Following the finishing treatment, the fiber mass becomes 5 , For example, a nonwoven fabric 5 , in a third fleece opener 41 Open and as a even fleece a belt dryer 29 fed. In the belt dryer 29 the drying of the fiber takes place 5 to the desired final moisture. Instead of a belt dryer can also be a screen drum dryer or any other drying device used become.

The Effectiveness of postcrosslinking and the effects of different Concentrations of sodium bisulfite or different pH ranges while The chemical reaction was investigated in a series of experiments. The experiments were cross-linked with glutaraldehyde and post-treated with sodium bisulfite Lyocell threads with a titre of 1.3 dtex / 38 mm. Of the in the respective Attempted lyocell fibers were both wet scratched and the glutardialdehyde content in the fibers. table I gives an overview of the Test results.

The Wet abrasion number, a characterizing fibrillation tendency Characteristic, was with a fiber wet scrub tester NP der Company SMK precision mechanics Gera GmbH determines. The wet scrub number is the number of revolutions the scouring shaft to break the under defined bias clamped in the wet scrub tester Fiber. The preload weight is at a titer between 1.2 to 1.8 dtex 70 mg. The speed of the Scouring wave was 400 U / min, the wrap 45 °. The scouring wave is provided with a fabric hose.

to Determination of the content of glutaric dialdehyde became a fiber content in 30 parts of water for one hour at 40 ° C extracted to get the free glutaraldehyde in solution. Subsequently was the watery Extract separated from the fibers and derivatized with dinitrophenyl hydrazine. The qualitative determination of the glutaric dialdehyde derivative was determined by means of LC-MS performed. The calibration of the glutaraldehyde content was carried out by means of a standard straight line, which from glutaraldehyde solution was created with known concentrations. The quantitative determination of glutaraldehyde is, for example, in the leather, Issue 5, pages 117 ff., 1992.

In all experiments, the lyocell fibers were in the first treatment step 7 crosslinked at a concentration of 23 g / l glutaric dialdehyde and a concentration of 30 g / l MgCl ₂ · 6H ₂ O as a catalyst.

In trial 1 was no prewash 13 the crosslinked lyocell fibers. In the second post-treatment zone 8th The fibers were treated directly with 0.3 g / l NaHSO ₃ . The pH of the sodium bisulfite solution was adjusted to 3.8. The residence time of the threads 5 in the chemical reaction zone 14 was about 3 minutes. After chemical reaction, the fibers were put into two final purification stages 15 washed with demineralised (VE) water, the water in contrast to the representation of 1 was circulated.

attempt 2 Essentially, this was a trial 1 , Deviating from trial 1 was at trial 2 However, a NaHSO ₃ concentration of 1.46 g / l used for the chemical reaction and the pH adjusted to 5.33. In addition, the demineralised water of the two Endwaschstufen were not performed in circulation, but derived.

In trial 3 were the crosslinked fibers S of the first post-treatment stage 7 initially treated in three pre-wash zones with demineralised water. The squeezed demineralised water of the pre-wash stages was removed. The chemical reaction was carried out with 2.0 g / l NaH-SO ₃ at pH adjusted to 8.7. Finally, the fibers were rinsed once with deionized water.

The experimental procedure of trial 4 is essentially the same as the trial 3 , When trying 4 A solution with a NaHSO ₃ concentration of 0.96 g / l and a pH adjusted to 4.23 was used for the chemical reaction.

In the trial 5 was the same experimental arrangement as in trial 3 hazards. Deviating was in trial 5 a NaHSO ₃ concentration of 4.73 g / l used. The pH of the NaNSO ₃ solution was 4.05, with no adjustment of the pH of this solution was carried out.

The attempt 6 became analogous to trial 5 carried out. However, in trial 6 a 9.53 g / L NaNSO ₃ concentration was used for chemical reaction, resulting in a pH of 4.36 in the reaction solution.

attempt 7 is a control experiment in which the fibers were cross-linked with glutaraldehyde. In the second post-treatment, the crosslinked fibers were washed with water only. No chemical reaction with sodium bisulfite was not carried out.

Table I summarizes the experimental conditions during the chemical reaction in the inactivation zone 14 the post-treatment and the content of free glutardialdehyde or the wet rubbing number of the produced lyocell fibers together. Table I

From the experiments in Table I, there is a surprising increase in the wet scrubbing rate of the post-treated fibers when the deionized water used for washing is removed (Experiments 2 to 6 ) and not used again (trial 1 ) has been. Furthermore, it is surprisingly found that the wet abrasion of the fibers by a pre-wash with deionized water, as in the experiments 3 to 6 was carried out again compared with the pure post-treatment with sodium bisulfite could be increased. The experiments 2 to 6 prove that can be made by the inventive aftertreatment cellulose fibers having a wet abrasion of at least 400 ago. In particular, cellulose fibers having a wet abrasion number of at least 600 can be produced.

Further is in the according to the inventive method fibers produced less than 150 mg of crosslinking agent per kg Fiber, in most experiments even less than 75mg of crosslinking agent per kg of fiber.

consequently prove the experiments that by the inventive aftertreatment crosslinked cellulose fibers with a bisulfite solution fibers with a high wet abrasion rate and a low content of free Glutardialdehyde can be produced in the fiber.

The content of glutaric dialdehyde per kg of fiber as a function of the sodium bisulfite concentration used is shown graphically in FIG 3 shown. In 3 are the above experiments 1 . 2 . 4 . 5 and 6 added. attempt 3 was omitted because the pH in the liquor was too high from the pH values of the experiments 1 . 2 . 4 . 5 and 6 differ.

As in the graph of 3 shown, the content of glutaraldehyde per kg of fiber decreases exponentially with increasing Natriumbisulfitkonzentration. Therefore, at the high sodium bisulfite concentration of 9.5 g per liter, the lowest glutaraldehyde content was measured. However, it should also be considered that at high sodium bisulfite concentrations of trial 6 the wet scouring rate of the fibers produced versus trial 5 slightly sinks.

In 4 the content of glutaric dialdehyde per kilogram of fiber is shown as a function of the pH of the solution used for the chemical reaction. In order to reduce the decrease in the glutaraldehyde content in the fibers to the change in pH, the graph of 4 the samples of the experiments 1 to 6 in which comparable sodium bisulfite concentrations were used.

The course of the curve of 4 corresponds essentially to the course of the curve of 2 , The content of glutaraldehyde decreases with increasing pH values. As from the course of the compensation curve of 4 As can be seen, the pH of the solution used for the chemical reaction should be adjusted to over 4.0.

Also if in the embodiment cross-cut staple fibers and post-treated, Thus, the post-treatment by crosslinking with glutaraldehyde and a chemical reaction with sodium bisulfite also be carried out on continuous moldings. Furthermore, the device according to the invention and the method according to the invention for post-treatment is not limited to lyocell fibers, but can for any solvent-spun or regenerated cellulose used in the fibrillation should be minimized. It is also not necessary, only never-dried, spun-wet to use cellulose fibers. Rather, can with the method according to the invention and the device according to the invention just as well already dried and then moistened fibers be treated.

Claims (15)

Process for the post-treatment of cellulose fibers, in particular for reducing the fibrillation tendency of lyocell fibers and filaments, wherein in a first post-treatment phase a Crosslinking agent having at least two functional groups, the react chemically with cellulose, preferably carbonyl groups, is brought into contact with the cellulose fibers, characterized in a second after-treatment phase, free crosslinking agent, which in the first post-treatment phase not chemically with cellulose reacted, is reacted chemically with a bisulfite compound. Method according to claim 1, characterized in that the crosslinking agent is a dialdehyde. Method according to claim 2, characterized in that the crosslinking agent is glutaric dialdehyde. Method according to one of the above claims, characterized characterized in that sodium bisulfite used as bisulfite compound becomes. Method according to one of the above claims, characterized characterized in that bisulfite ion concentrations of 0.38 g / l to 16 g / l is used. Method according to Claim 6, characterized that a Bisulfitionenkonzentration of 0.75 g / l used to 8 g / l becomes. Method according to claim 5 or 6, characterized that a bisulfite ion concentration between 3.0 g / l and 4.7 g / l is used. Method according to one of the above claims, characterized characterized in that the chemical reaction of the crosslinking agent at pH 4 to 10 becomes. Method according to claim 8, characterized in that that the chemical reaction of the crosslinking agent at pH 4.5 to 6 performed becomes. Method according to one of the above claims, characterized characterized in that the cellulose fibers in the second treatment phase before the chemical reaction of the free crosslinking agent at least to be washed once. Apparatus for aftertreatment of cellulose fibers, in particular for reducing the fibrillation tendency of lyocell fibers or filaments, with a first stage of treatment with a cellulose cross-linking Crosslinking agent and a washing device for the treatment of crosslinked cellulose fibers with a washing solution characterized by a second treatment step with a bisulfite solution for the chemical conversion of the Crosslinking agent. Cellulose fiber or filaments, in particular lyocell fibers or filaments prepared by the method according to one the claims 1 to 10, characterized by less than 150 mg of crosslinking agent per Kilograms of fiber. Cellulose fibers according to claim 12, characterized by less than 75 mg crosslinker per kilogram of fiber. Cellulose fiber according to claim 12 or 13, characterized by 10 mg to 30 mg of crosslinking agent per kilogram of fiber. Cellulose fibers according to claim 13 or 14, characterized by a wet abrasion number of at least 300, preferably from at least 400.