EP0659219A1

EP0659219A1 - Cellulose fibres.

Info

Publication number: EP0659219A1
Application number: EP94921517A
Authority: EP
Inventors: Hartmut Ruef; Markus Eibl; Raimund Jurkovic
Original assignee: Lenzing AG; Chemiefaser Lenzing AG
Current assignee: Lenzing AG
Priority date: 1993-07-08
Filing date: 1994-07-08
Publication date: 1995-06-28
Anticipated expiration: 2014-07-08
Also published as: HUT72230A; ATE133724T1; HU9500591D0; NO950865D0; TR28323A; YU48582B; ID913B; WO1995002082A1; GR3019296T3; EP0659219B1; CN1112367A; CN1090249C; JP2768831B2; HK1000327A1; US5543101A; DE59400105D1; PE696A1; DK0659219T3; FI951057A; HRP940392B1

Abstract

The invention concerns a method of manufacturing cellulose fibres by extruding a solution of cellulose in a tertiary-amine oxide through the holes of a spinneret and passing the extruded filaments under tension through an air gap and into a regenerating bath. The method is characterized in that it is carried out in such a way that the maximum value of the mathematical expression 51.4 + 0.033xD + 1937xM<2> - 7.18xT - 0.094xL - 2.50xF + 0.045xF<2> in which D is the spinneret-hole diameter in mu m, M is the spinning-solution throughput per hole in g/min, T is the titre of a single filament in dtex, L is the length of the air gap in mm and F is the humidity of the air in the air gap in g of water per kg of air, is 10, with the provision that the length of the air gap is greater than 30 mm. This method gives cellulose fibres with a very low tendency to fibrillation.

Description

Cellulose fiber

The present invention relates to cellulose fibers and to a process for the production of cellulose fibers, a solution of cellulose in a tertiary amine oxide being extruded through spinning holes in a spinneret and the extruded filaments being passed over an air gap with delay into a precipitation bath.

As an alternative to the viscose process, a number of processes have been described in recent years in which cellulose is dissolved in an organic solvent, a combination of an organic solvent with an inorganic salt or in aqueous salt solutions without the formation of a derivative. Cellulose fibers made from such solutions were given the generic name Lyocell by BISFA (The International Bureau for the Standardization of man made Fibers). BISFA defines a cellulose fiber as Lyocell, which is obtained from an organic solvent by a spinning process. BISFA understands "organic solvent" as a mixture of an organic chemical and water. "Solvent spinning" is intended to mean dissolving and spinning without derivatization.

To date, however, only a single process for the production of a cellulose fiber of the Lyocell type has prevailed until industrial implementation. In this process, N-methylmorpholine-N-oxide (NMMO) is used as the solvent. Such a method is described, for example, in US Pat. No. 4,246,221 and provides fibers which are distinguished by a high strength, a high wet modulus and by a high loop strength. The usability of fabrics, for example fabrics made from the fibers mentioned, is severely limited by the pronounced tendency of the fibers to fibrillate when wet. Fibrillation is understood to mean breaking open the fiber in the longitudinal direction under mechanical stress in the wet state, as a result of which the fiber is given a hairy, furry appearance. A fabric made and dyed from these fibers loses its color intensity over the course of a few washes. In addition, there are bright stripes on the scuffed and crease edges. The cause of the fibrillation is assumed to be that the fiber consists of fibrils arranged in the direction of the fibers, between which there is only a small amount of cross-connection.

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

WO 92/07124 also describes a method for producing a fiber with a reduced tendency to fibrillation, according to which the undried fiber is treated with a cationic polymer. A polymer with imidazole and azetidine groups is mentioned as such a polymer. In addition, treatment with an emulsifiable polymer, e.g. Polyethylene or polyvinyl acetate, or crosslinking with glyoxal.

In a lecture given by S. Mortimer at the 1993 CELLUCON conference in Lund, Sweden, it was mentioned that the tendency to fibrillation increased with increasing stretching.

It has been shown that the known cellulose fibers of the Lyocell genus still leave something to be desired with regard to the tendency to fibrillation, and the present invention provides the task is to provide a cellulose fiber of the Lyocell genus, which has a further reduced tendency to fibrillation.

This goal is achieved in a method of the type described in the introduction in that methods are carried out in such a way that the mathematical expression

51.4 + 0.033xD + 1937xM ² - 7.18xT - 0.094xL - 2.50xF + 0.045xF ²

where D is the spinning hole diameter in μm, M is the spinning mass output per hole in g / min, T is the titer of the individual filament in dtex, L is the width of the air gap in mm and F is the humidity of the air in the air gap in g of water / kg of air , the maximum is 10, with the proviso that the width of the air gap is provided to be greater than 30 mm.

The invention is based on the knowledge that the structure of the cellulose fiber can be influenced so favorably by setting the spinning parameters that a less fibrillating fiber is formed.

A preferred embodiment of the method according to the invention is that the method is carried out in such a way that the mathematical expression results in a maximum of 5.

The resulting parameters titer, spinning mass emissions per nozzle hole, air gap width and moisture in the air gap are related in terms of their effect on the fibrillation behavior of the fibers via the above mathematical expression, that is, a change in a parameter which has a negative effect on fibrillation can be achieved by appropriate adjustment one or more other parameters can be compensated. This naturally results Limits due to economic or technical circumstances, for example a spinning mass throughput of 0.01 g / hole / min offers excellent conditions for spinning a low-fibrillation fiber, but is unfavorable for economic reasons. A spinning mass throughput of 0.025 to 0.05 g / hole / min is therefore preferred.

It has also been shown that large air gap widths have a positive effect on the fibrillation behavior, but that this leads to the occurrence of spinning defects relatively quickly in the small hole / hole spacings used in staple fiber nozzles. An air gap width of less than 100 mm is therefore preferred.

With regard to the humidity of the air in the air gap, the humidity of the normal indoor climate is sufficient for nozzles with a small diameter of the spinning holes or the lowest spinning mass throughput, while for higher throughputs or for the more easily spinnable nozzles, an air humidity between 20 and 30 g is sufficient Water / kg air is preferred. The temperature in the air gap is chosen so that on the one hand the dew point is not fallen below, i.e. that no water condenses in the air gap and on the other hand that there are no difficulties in spinning due to the temperature being too high. Values between 10 and 60 ° C. can be set, with temperatures between 20 and 40 ° C. being preferred.

All known cellulosic spinning materials can be processed by the process according to the invention. So these spinning masses can contain between 5 and 25% cellulose. However, cellulose contents between 10 and 18% are preferred. Hard or softwood can be used as the raw material for pulp production, and the degrees of polymerization of the pulp (s) can be in the range of commercially available products. However, it has been shown that the spinning behavior is better with a higher molecular weight of the pulp is. The spinning temperature may range, depending on the degree of polymerization of the pulp or solution concentration of 75-140 C and ^β, for each pulp and for each concentra- tion in a simple way be optimized. The warping in the air gap depends on the diameter of the nozzle hole and the concentration of cellulose in the solution when the titer of the fibers is fixed. In the area of the preferred cellulose concentration, however, it was not possible to determine any influence on the aging behavior as long as one is in the area of the optimal spinning temperature.

The test methods and preferred embodiments of the invention are described in more detail below.

Fibrillation assessment

The friction of the fibers against one another during washing processes or during finishing processes in the wet state was simulated by the following test: 8 fibers were placed in a 20 ml sample vial with 4 ml water and in a laboratory shaker type RO-10 from Gerhardt for 3 hours, Bonn (FRG) shaken at level 12. The fibrillation behavior of the fibers was then assessed under the microscope by counting the number of fibrils per 0.276 mm fiber length.

Textile data

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

Examples 1-29

A 12% spinning solution of sulfite and sulfate Cellulose (12% water, 76% NNMO) spun at a temperature of 115 ° C. A melt index device from Davenport used in plastics processing was used as the spinning apparatus. This device consists of a heated, temperature-controlled cylinder into which the spinning mass is poured. The spinning mass is extruded through the spinneret attached to the underside of the cylinder by means of a piston which is loaded with a weight. This process is called dry / wet spinning because the extruded filament is immersed in a spinning bath after passing through an air gap.

A total of 29 extrusion tests were carried out, the die diameter, the spinning mass output, the titer of the extruded filament, the width of the air gap and the moisture being varied. The results are shown in Table 1. The column "Fibrils" shows the average number of fibrils over a fiber length of 276 μm.

Table 1

Example hole throughput titer gap moist fibrils

No knife

1 130 0.014 2.16 85 39 4.8

2 130 0.014 2.13 130 16 0.4

3 130 0.015 2.37 40 21 0.8

4 (V) 130 0.041 1.23 85 0 38

5 130 0.043 2.14 85 21 0.4

6 130 0.043 2.13 85 20 1.6

7 130 0.042 2.08 85 20 0.3

8 130 0.041 2.03 85 20 5.4

9 130 0.039 1.94 85 19 5.0

10 130 0.042 2.95 40 19 0.8

11 130 0.039 3.09 85 40 3.5

12 (V) 130 0.102 2.21 130 21 18 13 (V) 130 0.102 2.22 85 0 54

14 (V) 130 0.100 2.23 85 38 22

15 50 0.015 2.37 85 18 3.2

16 50 0.043 2.28 130 18 0.0

17 50 0.045 2.41 40 20 0.6

18 50 0.042 2.25 85 40 0.0

19 50 0.041 2.88 85 18 0.0

20 (V) 250 0.040 1.32 85 20 14

21 250 0.041 2.35 130 18 2.7

22 (V) 250 0.041 2.18 40 22 14

23 250 0.040 2.93 85 19 0.8

24 200 0.017 2.00 85 21 0.0

25 200 0.041 1.30 85 20 8.0

26 200 0.041 2.17 130 18 0.8

27 200 0.040 2.14 40 19 10

28 200 0.041 2.90 85 20 0.6

29 (V) 200 0.100 2.16 85 22 19

The table shows the diameter of the spinning hole in μ, the output in g of spinning mass / hole / min, the titer in dtex, the air gap in mm and the moisture in g H ₂ 0 / kg air. The number given under "Fibrils" is an average of several results. Examples 4, 12, 13, 14, 20, 22 and 29 are comparative examples. All other examples are according to the invention and, when the corresponding parameters are inserted into the empirically found mathematical expression, result in a number less than 10. The table shows that the cellulose fibers according to the invention have remarkably fewer fibrils in the test than the comparison fibers.

Examples 30-41

The procedure was analogous to the conditions of Examples 1-29, the parameters being changed as indicated. In the The "Fibrils" column shows the average number of fibrils over a fiber length of 276 μm.

Table 2

Example hole throughput titer gap moisture] fibril

No knife

30 (V) 130 0.045 1.8 12 5.3 27

31 (V) 130 0.045 1.8 12 4.0 43

32 100 0.026 1.7 60 23.5 2.8

33 (V) 100 0.025 1.7 45 13.4 16

34 100 0.025 1.7 60 25.4 3.2

35 (V) 100 0.025 1.7 30 13.3 15.1

36 (V) 100 0.025 1.7 30 12.7 19

37 100 0.025 1.7 60 24.4 1.9

38 (V) 100 0.049 1.7 90 0.5 34

39 100 0.049 3.2 90 19.0 0

40 100 0.041 1.8 90 29.0 0.9

41 130 0.025 1.3 90 30.0 3.2

The spinning parameters are given in the units shown in Table 1.

Examples 30, 31, 33, 35, 36 and 38 do not meet the mathematical expression used according to the invention and represent comparative examples. The table shows that these fibers have an increased number of fibrils (more than 10 fibrils per 276 μm fiber length).

Table 3 shows characteristic fiber data for the fibers shown in Table 2. Table 3

E.g. fiber strength fiber elongation fiber strength fiber elongation

No. cond. cN / tex cond. % wet cN / tex wet%

30 (V) 46.1 10.5 33.8 14.2

31 (V) 50 11.3 41.4 14

32 31.9 17.7 27.5 24.5

33 (V) 34.3 15.2 29.1 23.5

34 28.8 16.5 24.5 21.8

35 (V) 34.1 14.8 29.3 19.8

36 (V) 33.3 16.3 30.5 18.8

37 29.4 17.2 23.9 21.3

38 (V) 30.4 11.8 22.5 14.3

39 25.6 15.6 19.5 22.5

40 24.6 14.8 18.2 21.4

41 28.5 15.8 24.2 20.9

Examples 42> to 54

The procedure was analogous to the conditions of Examples 1-29, the parameters being changed as indicated. The column "Fibrils" in Table 4 below shows the average number of fibrils over a fiber length of 276 μm.

Table 4

Example hole throughput titer gap moist fibrils

No knife

42 (V) 100 0.025 1.7 10 13 18.0

43 (V) 100 0.025 1.7 20 13 14.0

44 (V) 100 0.025 1.7 25 13 9.0

45 (V) 100 0.025 1.7 30 13 6.0

46 100 0.025 1.7 60 13 5.5

47 (V) 100 0.025 1.7 10 13 19.0 48 (V) 100 0.025 1.7 20 13 9,, 5

49 (V) 100 0.025 1.7 25 13 3,. 5

50 (V) 100 0.025 1.7 30 13 1,. 0

51 100 0.025 1.7 60 13 1.0

52 (V) 100 0.025 1.7 10 20 14

53 (V) 100 0.025 1.7 10 20 11,, 0

54 (V) 100 0.025 1.7 60 20 4.0

The spinning parameters are given in the units shown in Table 1.

Table 4 shows a significant reduction in the number of fibrils as soon as an air gap of about 25-30 mm is exceeded.

Claims

Claims:

1. A process for the production of cellulosic fibers by extruding a solution of cellulose in a tertiary amine oxide through spinning holes of a spinneret and the extruded filaments are passed over an air gap with delay into a precipitation bath, characterized in that the method is carried out in such a way that the mathematical Expression

51.4 + 0.033xD + 1937XM ² - 7.18xT - 0.094xL - 2.50xF + 0.045xF ²

2. The method according to claim 1, characterized in that the method is carried out so that the mathematical expression results in a maximum of 5.

3. The method according to any one of claims 1 or 2, characterized in that the spinning mass output per hole is between 0.025 and 0.05 g / min.

4. The method according to one or more of claims 1 to 3, characterized in that an air gap width of less than 100 mm is provided.

5. The method according to claim 1 or 2, characterized in that in a spinneret with spinning holes whose diameter is between 70 and 130 microns, the moisture the air in the air gap is set between 20 and 30 g water / kg air.

6. Cellulose fiber of the Lyocell genus with reduced

Fibrillation tendency, obtainable by a process of claims 1 to 5.