EP0823945B1 - Process for the manufacture of cellulose fibres - Google Patents

Abstract

PCT No. PCT/AT97/00041 Sec. 371 Date Oct. 30, 1997 Sec. 102(e) Date Oct. 30, 1997 PCT Filed Mar. 3, 1997 PCT Pub. No. WO97/33020 PCT Pub. Date Sep. 12, 1997The invention is concerned with a process for the production of cellulose fibers wherein a solution of cellulose in a tertiary amine-oxide is extruded through spinning holes of a spinneret, whereby filaments are extruded, the extruded filaments are conducted across an air gap, a precipitation bath and a drawing device whereby the filaments are drawn, the drawn filaments are further processed into cellulose fibers, the drawn filaments being exposed during further processing to a tensile stress in longitudinal direction not exceeding 5.5 cN/tex.

Description

The present invention relates to a method for Manufacture of cellulosic fibers. With this procedure a solution of cellulose in a tertiary amine oxide Spinning holes of a spinneret extrude, creating filaments be extruded, the extruded filaments through a Air gap, a precipitation bath and a fume cupboard with which the filaments are drawn, and the drawn filaments to cellulosic fibers processed further.

As an alternative to the viscose process, the last Years described a number of procedures in which Cellulose without the formation of a derivative in an organic Solvent, a combination of an organic Solvent with an inorganic salt or in aqueous Saline solutions is dissolved. Cellulose fibers made from such Solutions are produced by BISFA (The International Bureau for the Standardization of man made Fibers) was assigned the generic name Lyocell. As Lyocell will BISFA defines a cellulose fiber that is made possible by a Spinning process obtained from an organic solvent becomes. The "organic solvent" is used by BISFA Mixture of an organic chemical and water Roger that. "Solvent spinning" is meant to dissolve and spin mean without derivatization.

To date, however, only one method has been used Production of a cellulose fiber of the Lyocell genus up to industrial implementation. With this procedure is used as solvent N-methylmorpholine-N-oxide (NMMO) used. Such a method is e.g. in US-A-4,246,221 described and provides fibers that are characterized by a high strength, a high wet modulus and by a high Mark loop strength.

The utility of fabrics, e.g. Fabrics, made from the fibers mentioned, but is by the pronounced inclination of the fibers, when wet fibrillate, severely restricted. This is called fibrillation Breaking the fiber lengthways with mechanical Understanding stress when wet, causing the fiber gets a hairy, furry look. One of these fibers manufactured and dyed fabric loses in the course of some Washes strongly in color intensity. On top of that comes on Form scuffed and crease edges with bright stripes. As The cause of the fibrillation is believed to be the fiber consists of fibrils arranged in the fiber direction, between which only have a small cross-connection is.

WO 92/14871 describes a method for producing a Fiber with reduced tendency to fibrillation. This is achieved by all the baths with which the fiber is dried before the first drying comes into contact with a maximum pH of 8.5.

WO 92/07124 also describes a method for Production of a fiber with reduced tendency to fibrillation, according to which the non-dried fiber with a cationic Polymer is treated. As such a polymer is a Polymer with imidazole and azetidine groups called. In addition can still be treated with an emulsifiable polymer, such as e.g. Polyethylene or polyvinyl acetate, or one Crosslinking with glyoxal.

In the lecture "Spinning of fibers through the N-methylmorpholine-N-oxide process ", S.A. Mortimer and A. Peguy, CELLUCON conference 1993 in Lund, Sweden, published in "Cellulose and cellulose derivatives: Physico-chemical aspects and industrial applications ", Ed. J. F. Kennedy, G.O. Phillips and P-O. Williams, Woodhead Publishing Ltd., Cambridge, England, pp. 561-567 mentioned that the tendency to fibrillation increases with stretching increases.

From the lecture "Special features of the developed in the TITK Amine oxide process ", Ch. Michels, R. Maron and E. Taeger, Symposium "Alternative Cellulose - Manufacturing, Forming, Properties ", September 1994, Rudolstadt, FRG, published in Lenzinger reports 9/1994, pages 57-60 known that between the filament tension in the air gap and the mechanical properties of the fibers Connection exists. P. mentioned at the same symposium Weigel, J. Gensrich and H.-P. Fink in her lecture "Structure formation of cellulose fibers from amine oxide solutions", published in Lenzinger reports 9/1984, pages 31-36 that the fiber properties can be improved if that Drying the filaments is done without the Filaments are exposed to tensile stress.

DE-A - 42 19 658 and EP-A - 0 574 870 described that post-stretching of the precipitated Filaments the textile properties of the fibers, especially their stretch, adversely affected.

Cellulosic filaments are known from WO 96/18760 a strength of 50 to 80 cN / tex, an elongation at break of 6 up to 25% and a specific tear time of at least 300 s / tex exhibit. These filaments are used in the manufacture of a Exposed to tension in the range of 5 to 93 cN. It will disclosed that these fibers have a low tendency to fibrillation exhibit.

It has been shown that the known cellulose fibers Genus Lyocell with regard to fiber properties and Fibrillation tendency still leaves something to be desired, and that The present invention has in particular the object to provide a method with which fibers with improved properties are produced in which the so-called work capacity, that is the mathematical product from the fiber strength (conditioned) and the elongation (conditioned) is improved.

• eine Lösung von Cellulose in einem tertiären Aminoxid durch Spinnlöcher einer Spinndüse extrudiert wird, wodurch Filamente extrudiert werden,
• die extrudierten Filamente durch einen Luftspalt, ein Fällbad und über eine Abzugsvorrichtung geführt werden, mit welcher die Filamente verstreckt werden,
• die verstreckten Filamente zu cellulosischen Fasern weiterverarbeitet werden, wobei
• die verstreckten Filamente während der Weiterverarbeitung einer Zugbeanspruchung in Längsrichtung von nicht mehr als 5,5 cN/tex ausgesetzt werden.

This goal is achieved in a process for the production of cellulosic fibers by the combination of the measures that

• a solution of cellulose in a tertiary amine oxide is extruded through spinning holes of a spinneret, thereby extruding filaments,
• the extruded filaments are passed through an air gap, a precipitation bath and over a draw-off device with which the filaments are drawn,
• the drawn filaments are processed into cellulosic fibers, wherein
• the drawn filaments are subjected to a longitudinal tensile stress of no more than 5.5 cN / tex during further processing.

It has been shown that good fiber properties on the whole can be easily achieved in that the Further processing of the drawn filaments, that is for example washing out the tertiary amine oxide from the Filament and finishing, especially however also the transport of the filaments in the course of the Further processing, with the lowest possible tension Filaments should be made using the Tensile stress should not be higher than 5.5 cN / tex.

For the purposes of the present invention, the term includes "Processing" all steps on the filaments be carried out, including the transport of the filaments, after they hit the trigger's first stop have happened.

The drawn filaments are expediently used during cut for further processing and then washed.

It has also been shown that the length of the route, on which removes the filaments from the take-off spinneret are fed, an influence on the fiber properties insofar as the fiber properties are all the better the shorter this distance is. A preferred embodiment The inventive method is that the length this distance is a maximum of 12 m, in particular a maximum of 1 m.

• eine Lösung von Cellulose in einem tertiären Aminoxid durch Spinnlöcher einer Spinndüse extrudiert wird, wodurch Filamente extrudiert werden,
• die extrudierten Filamente durch einen Luftspalt, ein Fällbad und über eine Abzugsvorrichtung geführt werden, mit welcher die Filamente verstreckt werden,
• die verstreckten Filamente zu getrockneten cellulosischen Fasern weiterverarbeitet werden, wobei
• die Länge der Strecke, auf welcher die Filamente von der Spinndüse der Abzugsvorrichtung zugeführt werden, maximal 12 m, insbesondere maximal 1 m beträgt,
• und die verstreckten Filamente während der Weiterverarbeitung und vor einem gegebenenfalls vorgesehenen Schnitt über mehrere Galetten zu führt werden, die in Serie geschaltet sind, wobei die Geschwindigkeit jeder Galette kleiner ist als diejenige der unmittelbar vorangegangenen Galette.

The invention further relates to a method for producing cellulosic fibers, which is characterized by the combination of the measures that

• a solution of cellulose in a tertiary amine oxide is extruded through spinning holes of a spinneret, thereby extruding filaments,
• the extruded filaments are passed through an air gap, a precipitation bath and over a draw-off device with which the filaments are drawn,
• the drawn filaments are further processed into dried cellulosic fibers, where
• the length of the path on which the filaments are fed from the spinneret to the take-off device is a maximum of 12 m, in particular a maximum of 1 m,
• and the drawn filaments are passed over a plurality of godets which are connected in series during the further processing and before an optionally provided cut, the speed of each godet being lower than that of the immediately preceding godet.

According to the method according to the invention, all known ones cellulosic spinning masses are processed. So this can Spinning masses contain between 5 and 25% cellulose. Prefers however, cellulose levels are between 10 and 18%. As Hard or soft wood can be used as a raw material for the production of cellulose are used, the degree of polymerization of the Pulp in the area of technically common commercial products can lie. However, it has been shown that at higher Molecular weight of the pulp better spinning behavior is. Depending on the degree of polymerization of the Pulp or solution concentration between 75 and 140 ° C. and can be for any pulp or concentration can be optimized easily.

Below are the test methods and preferred Embodiments of the invention described in more detail.

Fibrillation assessment

The friction of the fibers against each other during washing processes or Finishing operations in the wet state was carried out by the following test simulated: 8 fibers were mixed with 4 ml of water in a 20 ml Sample vials given and in one for 9 hours Laboratory shaker type RO-10 from Gerhardt, Bonn (FRG) shaken at level 12. The fibrillation behavior of the fibers was then examined under the microscope by counting the number of fibrils per 0.276 mm fiber length.

Textile data

Strength and elongation were conditioned after the BISFA regulation "Internationally agreed methods for testing viscose, modal, cupro, lyocell, acetate and triacetate staple fibers and tows ", edition 1993, checked.

Testing the loop strength and elongation (conditioned)

The loop strength was checked by using two fibers formed a loop and this loop a tensile test has been subjected. Only those were used for averaging Fibers are used that tear at the loop.

To measure the loop strength and elongation a vibroscope is a Lenzing AG titre measuring device non-destructive titer determination using the vibration method and a vibrodyne, which is a device for tensile tests Single fibers with constant deformation speed, used.

The standard climate was air of 20 ° C and a relative Humidity of 65% taken.

example 1

It was spun in a 15% spinning solution of sulfite and sulfate pulp (9% water, 76% NMMO) at a temperature of 125 ° C with a spinneret having 100 spinning holes with a diameter of 100 μ m was obtained. The spinning mass output per minute was 0.017 g / hole. The titer of the individual filament was 1.9 dtex.

The filaments were passed through the air gap into the precipitation bath and led over a godet, with which a train on the Filaments was exerted, causing them to stretch in the air gap were. After passing the godet, the filaments were immediately cut and only then by washing out the amine oxide, Finishing and drying processed. The filaments were processed without tension. The textile data of obtained fibers are shown in Table 1.

Example 2 (comparison)

The procedure was analogous to Example 1, except that the Filaments after passing the godet, i.e. the first Breakpoint, not cut immediately, but another Galette were fed, which was 2.2 meters from the first Galette was removed. The speed of the second godet was set so that the filament cable between the first and second godets under a tension of 11.6 cN / tex stand.

After passing through the second godet, the filaments were cut immediately and only then processed further by washing out the amine oxide, finishing and drying. The filaments were therefore not processed without tension after the first stopping point. The textile data of the fibers obtained are shown in Table 1. example 1 Example 2 Cable tension (cN / tex) 0 11.6 Firmness cond. (cN / tex) 37.5 34.3 Elongation cond. (%) 15.0 10.8 Loop strength (cN / tex) 20.9 18.8 Snare elongation (%) 5.8 4.1 Fibrils 14 29 Work capacity 562 370

The column "Fibrils" shows the average number of fibrils over a fiber length of 276 µm . Working capacity is the mathematical product of strength (cond.) And elongation (cond.).

Table 1 shows that the voltage-free Processing the fibers a product with improved Properties. Above all, these properties the lower number of fibrils and the increased work capacity to emphasize.

Example 3

A spinning mass of the composition of Example 1 was at 120 ° C through a die with 1 spin hole, dtex extruded a diameter of 100 μ m to having filaments having an individual of 1.8. On the filaments produced, it was investigated how a stretching load affects the tendency to fibrillation by loading the filaments with different weights, the loading time also being varied. The results are shown in Table 2. Trial No. Load (cN / tex) Time (s) Number of fibrils A 2.2 10 1 B 2.2 600 4th C. 5.6 10 3rd D 5.6 600 8.9 E 10.9 10 7 F 10.9 600 12th

Experiments Nos E and F are comparative experiments. The table 2 shows that the tendency to fibrillation is all the more is more pronounced, the higher the load and the longer it acts on the filament.

Example 4

The procedure was analogous to Example 1, except that the distance from the spinneret to the godet was varied. The results are shown in Table 3. Trial 1 Trial 2 Trial 3 Distance nozzle / godet (m) 12th 25th 48 Titer (dtex) 1.30 1.39 1.29 Firmness cond. (cN / tex) 34.8 32.7 34.5 Elongation cond. (%) 11.8 11.6 11.1 Fibrils 38 38 41 Work capacity 403 379 383

The results of Table 3 show that the length the distance on which the filaments to Trigger device (godet) are performed, an influence on has the working capacity of the fiber insofar as that Work capacity decreases sharply if the distance is greater than 12 damn.

Claims (7)

1. A method for producing cellulose fibres, characterised by a combination of the following measures:

   a solution of cellulose in a tertiary amine oxide is extruded through the holes of a spinneret, whereby filaments are extruded,

   the extruded filaments are passed through an air gap, a coagulating bath and over a haul-off device, with which the filaments are drawn,

   the drawn filaments are further processed into cellulose fibres, wherein

   the drawn filaments are exposed to a tensile load in the longitudinal direction of not more than 5.5 cN/tex during further processing.
2. A method according to claim 1, characterised in that the drawn filaments are cut during further processing and then washed.
3. A method according to one of claims 1 or 2, characterised in that the length of the distance over which the filaments are fed from the spinneret to the haul-off device is at most 12 m.
4. A method according to claim 3, characterised in that the length of the distance over which the filaments are fed from the spinneret to the haul-off device is at most 1 m.
5. A method according to one of claims 1 to 4, characterised in that, during further processing and prior to optionally provided cutting, the drawn filaments are guided over a plurality or godets connected in series, the speed of each godet being less than that of the immediately preceding godet.
6. A method for producing cellulose fibres, characterised by a combination of the following measures:

   a solution of cellulose in a tertiary amine oxide is extruded through the holes of a spinneret, whereby filaments are extruded,

   the extruded filaments are passed through an air gap, a coagulating bath and over a haul-off device, with which the filaments are drawn,

   the drawn filaments are further processed into dried cellulose fibres, wherein

   the length of the distance over which the filaments are fed from the spinneret to the haul-off device is at most 12 m,

   and, during further processing and prior to optionally provided cutting, the drawn filaments are guided over a plurality of godets connected in series, the speed of each godet being less than that of the immediately preceding godet.
7. A method according to claim 6, characterised in that the length of the distance over which the filaments are fed from the spinneret to the haul-off device is at most 1 m.