MODIFIED VISCOSE FIBER

Abstract

The invention relates to a modified viscose fiber containing an incorporated material from algae. The fiber according to the invention is characterized by a wet modulus at an elongation of 5% in the wet state which complies with the following formula:

wet modulus (cN)0.5*T, wherein T is the titer of the fiber in dtex.

Claims

1. A modified viscose fiber containing comprising an incorporated algal material, wherein the fiber comprises a wet modulus at an elongation of 5% in the wet state which complies with the following formula:
wet modulus (cN)0.5*T, wherein T is the titer of the fiber in dtex.

2. The modified viscose fiber according to claim 1, wherein the fiber comprises a fiber strength in the conditioned state which complies with the following formula:
fiber strength (cN/tex)27.381.4*T.

3. The modified viscose fiber according to claim 1, wherein the fiber comprises a content of zinc ions of at least 200 ppm.

4. The modified viscose fiber according to claim 1, wherein the fiber comprises a content of algal material of at least 0.5% by weight.

5. A process for the production of the modified viscose fiber according to claim 1, comprising: spinning a viscose having a content of 4% by weight to 7% by weight of cellulose, 5% by weight to 10% by weight of NaOH, 34% by weight to 42% by weight (based on cellulose) of carbon disulphide and 1% by weight to 5% by weight (based on cellulose) of a modifier into a spinning bath, and drawing off the coagulated filaments; wherein the viscose comprises a spinning gamma value ranges from 50 to 68 and a spinning viscosity which ranges from 50 falling-ball seconds to 150 falling-ball seconds; wherein the alkali ratio (cellulose concentration/alkali content) of the viscose ranges from 0.7 to 1.5, and a temperature of a spinning bath ranges from 34 C. to 48 C., wherein the spinning bath comprises: TABLE-US-00011 H2SO4 68 g/l-90 g/l Na2SO4 90 g/l-160 g/l ZnSO4 30 g/l-65 g/l, wherein a final draw-off from the spinning bath occurs at a rate of between 15 m/min and 60 m/min, and wherein an algal material in the form of an aqueous dispersion is spun in.

6. The process according to claim 5, wherein the aqueous dispersion has a content of algal material of 2% by weight to 15% by weight.

7. A yarn comprising the modified viscose fiber according to claim 1.

8. The modified viscose fiber according to claim 3, wherein the content of zinc ions is 200 ppm to 700 ppm.

9. The modified viscose fiber according to claim 4, wherein the content of algal material is 2% by weight to 6% by weight.

10. A planar textile assembly comprising the modified viscose fiber according to claim 1.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0011] FIG. 1 illustrates the fibrillation dynamics of cellulosic fibers as determined according to an adapted Canadian Standard Freeness test.

[0012] FIG. 2 shows the microscopic assessment of the fibrillation behavior of a fiber according to Example 3.

[0013] FIG. 3 shows the fibrillation behavior of a fiber according to Example 4.

[0014] FIG. 4 shows the fibrillation behavior of a SeaCellTM fiber.

DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention solves the above-indicated problem by providing non-fibrillating regenerated cellulosic fibers with incorporated algal material, which are produced according to a viscose process modified in comparison to EP 1 259 564. The fibers according to the invention are characterized by the particular softness of cellulose fibers with an incorporated material from algae, which per se is known, but exhibit a significantly reduced tendency towards wet fibrillation as compared to solvent-spun fibers based on the NMMO process.

[0016] Surprisingly, the minor procedural modifications in comparison to the manufacturing process described in EP 1 259 564 B1 have had the result that the fibers according to the invention show significantly improved physical fiber properties, in particular a higher fineness-related tear strength and a higher wet modulus, as compared to the fibers of the viscose type having brown algae incorporated according to EP 1 259 564, Example 7 (comprising 15% brown algae) and Example 8: (comprising 1.67% brown algae on cellulose) and even in comparison to Comparative Example 3 of EP 1 259 564 (without admixture of algae).

[0017] The fibers according to the invention have a wet modulus at an elongation of 5% in the wet state which complies with the following formula:

wet modulus (cN)0.5*T,

[0018] wherein T is the titer of the fiber in dtex.

[0019] This wet modulus corresponds to the wet modulus of a modal fiber as per the definition by BISFA (The International Bureau for the Standardization of Man-Made Fibers) and is hereinafter also referred to as BISFA wet modulus or BISFA modulus. The wet modulus and the other textile physical properties mentioned in the present application are measured according to the measuring methods as defined by BISFA.

[0020] In a preferred embodiment, the fiber according to the invention has a fiber strength in the conditioned state which complies with the following formula:

fiber strength (cN/tex)27.381.4*T.

[0021] This strength is significantly higher than that of the modified viscose fibers described in EP 1 259 564.

[0022] The fibers according to the invention may contain 0.5% by weight to 6% by weight, preferably 2% by weight to 6% by weight, particularly preferably 3% by weight to 4% by weight, of algal material, based on cellulose.

[0023] The algae can come from both salt and fresh water. The use of microalgae as well as of macroalgae, especially also kelp, is possible.

[0024] Preferably, the algae used have an alginic acid content of 15% by weight to 50% by weight. In a preferred embodiment, the fibers according to the invention contain algal material of the type Ascophyllum nodosum.

[0025] Moreover, the fibers according to the invention have, even without complementary additions of metal ions, an increased content of zinc in comparison to Lyocell fibers and/or viscose fibers with the same addition of algae.

[0026] The content of zinc ions preferably amounts to at least 200 ppm, particularly preferably 200 ppm to 700 ppm.

[0027] The zinc content is significantly increased also in comparison to modal fibers and is present in the fiber according to the invention at least partially as a Zn alginate. Zinc is an essential trace element with skin-caring qualities and is therefore used in skin care products. Zinc alginates are used, among other things, in wound dressings. It is believed that the combined effect of alginate (as a moisturizer and a natural softener) and of zinc ions releasable from the alginate achieves even better skin care properties.

[0028] A process serves for the production of the viscose fiber according to the invention which consists in spinning a viscose having a content of 4% by weight to 7% by weight of cellulose, 5% by weight to 10% by weight of NaOH, 34% by weight to 42% by weight (based on cellulose) of carbon disulphide as well as 1% by weight to 5% by weight (based on cellulose) of a modifier into a spinning bath, drawing off the coagulated filaments; wherein a viscose is used whose spinning gamma value ranges from 50 to 68 and whose spinning viscosity ranges from 50 falling-ball seconds to 150 falling-ball seconds; wherein the alkali ratio (=cellulose concentration/alkali content) of the viscose ready for spinning ranges from 0.7 to 1.5, and the temperature of the spinning bath ranges from 34 C. to 48 C., wherein the following spinning bath concentrations are used:

TABLE-US-00001 H2SO4 68 g/l-90 g/l Na2SO4 90 g/l-160 g/l ZnSO4 30 g/l-65 g/l,

[0029] wherein the final draw-off from the spinning bath occurs at a rate of between 15 m/min and 60 m/min, and wherein an algal material in the form of an aqueous dispersion is spun in.

[0030] The numerical values indicated for the composition of the viscose refer to its state prior to the addition of the dispersion of the algal material.

[0031] A process similar in terms of the parameters of the viscose used, the spinning bath and the spinning has been described in WO 2011/026159 A1 so that reference can be made to this document for further details regarding the spinning process.

[0032] The modifier which is used produces a sheath structure of the fiber according to the invention in a manner known per se. For example, the modifier can be an ethoxylated amine.

[0033] The material from algae which is used is preferably provided in a powdered and dried state, with a residual water content of <15%, better <10%, at a particle size of x9920 m, better 15 m. So as to achieve the desired fiber properties, the algal material should preferably have an alginic acid content of at least 15%. Directly before use, the material is preferably dispersed in water, optionally with a dispersing aid being added, in order to yield a dispersion with a solids content preferably ranging from 2% by weight to 15% by weight. The aqueous dispersion can be deaerated in vacuo as needed and, optionally, can be added to the viscose at the desired ratio upon a preceding filtration for removing undissolved particles, while, in doing so, intimate mixing should be ensured by means of conventional mixing units, homogenizers or the like. Upon admixture to the viscose, a filtration by cartridge filters may occur prior to spinning.

[0034] Spinning may be effected through spinnerets with a hole diameter of 50 m-100 m, depending on the desired titer of the fibers.

[0035] The present invention also relates to the use of the viscose fiber according to the invention for the production of yarns and planar textile assemblies.

[0036] The invention shall now be explained by way of examples. These are to be understood as possible embodiments of the invention. By no means is the invention limited to the scope of those examples.

[0037] A detailed listing of the process parameters of all examples can be found in Table 9 at the end of the example section.

EXAMPLE 1

Preparation of a Modified Viscose Fiber Algae-Incorporated According to the Invention

[0038] A 10% dispersion was prepared in demineralized water from a dried, powdered plant material of Ascophyllum nodosum and was deaerated for 6 hours. A viscose fiber without or, respectively, with 2.5% or, respectively, 5% algal material on cellulose was produced through spinnerets with a hole diameter of 50 m and with a draw-off of 30 m/min. The dosing of the algal dispersion took place directly before the homogenizer, with a residence time of <1 min in front of the spinneret.

TABLE-US-00002 TABLE 1 Fiber properties of a modified viscose fiber, Example 1 wet modulus Algae (Bisfa [%] on titer FFk FDk FFn FDn modulus) cell. [dtex] [cN/tex] [%] [cN/tex] [%] [cN/tex] 0 (none) 1.72 39.0 11.8 23.2 13.5 6.4 2.5 1.71 31.3 10.6 18.6 12.1 5.6 5 1.79 31.3 11.4 17.2 12.1 5.3
Legend (Also Applies to the Following Tables): Titer [dtex]: fineness (conditioned)FFk [cN/tex]: fineness-related tear strength dry and, respectively, conditionedFDk [%]: maximum tensile force elongation dry and, respectively, conditionedFFn [cN/tex]: fineness-related tear strength wetFDn [%]: maximum tensile force elongation wet

[0039] Wet modulus (Bisfa modulus) [cN/tex]: fineness-related wet modulus at 5% elongation

EXAMPLE 2

Preparation of a Modified Viscose Fiber Algae-Incorporated According to the Invention Using Differently Concentrated Powder Dispersions

[0040] A 10%, a 5% and a 2.5% dispersion was prepared in demineralized water from a dried, powdered plant material of Ascophyllum nodosum, and the dispersions were not deaerated. A viscose fiber without or, respectively, with, in each case, 5% algal material on cellulose was produced through spinnerets with a hole diameter of 50 m and with a draw-off of 30 m/min.

TABLE-US-00003 TABLE 2 Fiber properties of a modified viscose fiber, Example 2 wet modulus Algae concentration of (Bisfa [%] on the algal titer FFk FDk FFn FDn modulus) WRV cell. dispersion [g/kg] [dtex] [cN/tex] [%] [cN/tex] [%] [cN/tex] [%] 0 (none) 1.76 36.6 12.6 22.7 14.9 5.9 66 5 100 1.83 23.5 11.2 11.1 12.2 4.1 81 5 50 1.98 28.4 12.7 15.3 14.8 4.5 79 5 25 1.89 29.1 11.8 17.4 13.2 5.6 86 Legend (also applies to the following tables): WRV [%]: water retention capacity.

[0041] Due to the high viscosity, the algal dispersion having the highest concentration still contained many air bubbles, which frequently resulted in thread breakages during spinning. Therefore, proper drawing and higher strengths could not be achieved in this case. When thinner algal dispersions were dosed in, this problem did not occurthe resulting fineness-related strengths are at a significantly higher level than that of a viscose fiber according to EP 1 259 564.

[0042] The alginic acid content of the algal material used and of the fibers thus spun was analyzed upon a total hydrolysis of the fiber via HPLC on the basis of the mannuronic acid and guluronic acid content against an alginic acid standard (Fluka). The alginic acid content of the algal powder used was 25%, the alginic acid content of the fibers was between 0.95% and 1.2%, corresponding to a content of algae of 3.8% to 4.8%.

[0043] As can be seen in Table 2, the fibers thus produced also have a significantly increased water retention capacity (WRV) compared with a modified viscose fiber without addition of algae. This shows the moisture retention capacity of the algal additive.

EXAMPLE 3

Preparation of a Modified Viscose Fiber Algae-Incorporated According to the InventionIncorporation of 4% Algal Powder (Ascophyllum Nodosum) on Cellulose, Metered as a 6% Dispersion in Water

[0044] A viscose fiber without or, respectively, with 4% algal material on cellulose was produced through spinnerets with a hole diameter of 60 m and with a draw-off of 20 m/min.

TABLE-US-00004 TABLE 3 Fiber properties of a modified viscose fiber, Example 3 Algae titer FFk FDk [%] on cell. [dtex] [cN/tex] [%] 0 (none) 1.79 31.2 14.6 4 1.75 27.4 13.5

[0045] The alginic acid content of the fibers thus spun amounted to 0.77% to 0.83%, corresponding to a content of algae of 3.35%-3.60%, the algal powder used had an alginic acid content of 23%.

EXAMPLE 4

Preparation of a Modified Viscose Fiber Algae-Incorporated According to the InventionIncorporation of 4% Algal Powder (Ascophyllum Nodosum) on Cellulose, Metered as a 6% Dispersion in Water

[0046] Viscose fibers modified according to the invention comprising 4% algal material on cellulose were produced through spinnerets with a hole diameter of 60 m and with a draw-off of 19 m/min for approx. 40 hours.

TABLE-US-00005 TABLE 4 Fiber properties of algae-incorporated modified viscose fibers, Example 4 Bisfa (5%) Algae titer modulus [%] on titer Cv FFk FDk FFn FDn wet SFk SDk Kfk cell. [dtex] [%] [cN/tex] [%] [cN/tex] [%] [cN/tex] [cN/tex] [%] [cN/tex] 4 1.67 9 27.5 12.6 14.2 12.6 4.5 9 2.8 18.1 Legend (also applies to the following tables): Titer Cv: [%]: standard variation coefficient SFk [cN/tex]: fineness-related loop strength conditioned SDk [%]: loop elongation conditioned

[0047] The alginic acid content of the fibers thus spun was 0.80% - 1.0%, corresponding to a content of algae of 3.2% - 4.0%; the algal powder used had an alginic acid content of 25%.

[0048] Zinc contents of the modified viscose fibers algae-incorporated according to the invention:

[0049] The zinc content was determined after fiber pulping by means of ICP analysis on fiber samples from Example 3 and Example 4 in comparison to a standard viscose fiber (manufacturer: Lenzing AG), a modal fiber (manufacturer: Lenzing AG) as well as an algae-modified fiber produced according to the Lyocell process (SeaCell, manufacturer: Smartfiber AG).

[0050] It was shown that the modified viscose fibers algae-incorporated according to the invention have a zinc content of 330 ppm to 530 ppm, whereas standard viscose fibers and modal fibers exhibit significantly lower zinc contents.

TABLE-US-00006 TABLE 5 Zn content of the modified viscose fibers algae-incorporated according to the invention and of comparative fibers Algae Zn [%] [mg/kg] Fiber sample Example 3 4 410 Example 4, fiber sample 1 4 530 Example 4, fiber sample 2 4 330 Example 4, fiber sample 3 4 400 Example 4, fiber sample 4 4 360 Example 4, fiber sample 5 4 380 Standard viscose fiber (textile type) 0 41 Modal fiber A 0 73 Modal fiber B 0 165 SeaCell fiber 3-5 5
Comparison of the fibers produced according to the invention with the prior art from EP 1 259 564:

[0051] 1) Comparison of the Tendency Towards Fibrillation with a Commercially Available SeaCell Fiber.

[0052] This fiber is a Lyocell type produced according to EP 1 259 564 with 3%-5% incorporated material of Ascophyllum nodosum.

[0053] To study the fibers' tendency towards fibrillation, the following procedures were used:

[0054] a) Wet abrasion valuemethod according to EP 0 943 027 B1 [0030]

[0055] b) Adapted CSF test based on the Canadian Standard Freeness T 227 om-99 standard

[0056] c) Shake test and microscopic assessment of the tendency towards fibrillationmethod according to EP 0 943 027 B1 [0029]

a) Examination of the Wet Abrasion Value (Also Wet Abrasion Resistance or NSF):

[0057] 20 single fibers are weighted down with a titer-dependent pretension weight and suspended from a metal roller with a diameter of 1 cm. The roller is covered with a viscose filament yarn stocking and is continuously moistened. During the measurement, the roller is rotated at a speed of 500 rpm. The roller simultaneously performs a pendulum movement transversely to the fiber axis with a deflection of about 1 cm. The number of rotations until the fibers are worn through is determined. The stronger the tendency towards fibrillation in the wet state, the lower is the number of achieved revolutions U, which indicate the value of the wet abrasion resistance based on the titer [dtex].

TABLE-US-00007 TABLE 6 Results of a wet abrasion test performed on fibers with incorporated algae, all 1.7 dtex Wet abrasion value (NSF) NSF CV Fiber type/production [U/dtex] [%] Example 2, 5% algae owc 2954 2 Example 4, 4% algae owc 2151 26 Seacell, Smartfiber AG, Lyocell process 18 27 Legend: CV [%]: coefficient of variation (standard deviation in % of the mean value)

b) Adapted CSF Test ,Canadian Standard Freeness' (CSF):

[0058] In the adapted ,Canadian Standard Freeness' test, a mixer serves as a measure of the tendency towards fibrillation, wherein fiber samples cut to a length of 5 mm are beaten in water in said mixer until they start to fibrillate. The CSF apparatus itself consists of a funnel with an overflow and a screen inserted therein. As the degree of fibrillation increases, the screen located in the CSF apparatus clogs, whereby more water gets into the overflow and less into the passage. In a standardized measuring cylinder, the water volume is determined in ml in the passage after various mixing times, whereby it is the higher, the less the fiber fibrillates.

[0059] FIG. 1 illustrates the fibrillation dynamics determined according to those experiments. The abscissa indicates the mixing time in minutes, the ordinate indicates the water volume in the passage in ml.

[0060] The fiber types A to F examined according to FIG. 1 were the following fibers:

[0061] A standard Lyocell fiber 1.7 dtex

[0062] B viscose fiber without algae 1.7 dtex from Example 2

[0063] C algae-incorporated modified viscose fiber from Example 2

[0064] D algae-incorporated modified viscose fiber from Example 4

[0065] E normal viscose fiber 1.7 dtex

[0066] F 1.7 dtex SeaCellTM (Smartfiber AG), Lyocell-based algae-incorporated type

[0067] As shown in FIG. 1, both Lyocell types, the standard Lyocell fiber as well as SeaCell, fibrillate already after a mixing time of 10 minutes. All fiber types based on a viscose process, i.e., also the algae-incorporated fibers according to the process modified according to the invention, still show no signs of fibrillation in the CSF test even after a mixing time of 45 minutes.

c) Degree of Fibrillation Using a Shake Test and Microscopic Assessment

[0068] The friction of the fibers among each other during washing and, respectively, finishing operations in the wet state is simulated by the following test: 8 fibers are placed in a 20 ml sample vial with 4 ml of water and shaken at level 12 for 3 hours in a laboratory shaker of type RO-10 from Gerhardt, Bonn (FRG). Thereupon, the fibrillation behavior of the fibers is evaluated under the microscope by counting the number of fibrils per 0.276 mm of fiber length and is indicated as a fibrillation value ranging from 0 (no fibrils) to 6 (strong fibrillation).

TABLE-US-00008 TABLE 7 Splice test after the shake test, number of fibrils and grade after 3 hours fibrils grade sam- sam- sam- sam- Fiber type/production ple A ple B ple A ple B Fiber from Example 3, 4% algae owc 0 0 0 0 Fiber from Example 4, 4% algae owc 0 8 0 0 SeaCell, Smartfiber AG, Lyocell process >50 >50 3 3

[0069] FIGS. 2 to 4 show the result of the microscopic examination of the fibers:

[0070] FIG. 2 shows the fibrillation behavior of the fiber according to Example 3.

[0071] FIG. 3 shows the fibrillation behavior of the fiber according to Example 4.

[0072] FIG. 4 shows the fibrillation behavior of the SeaCell fiber.

[0073] It is clearly evident that the fibers according to the invention do not or practically do not fibrillate.

[0074] 2) Comparison of the Physical Fiber Properties of the Algae-Incorporated Modified Viscose Fibers Produced According to the Process According to the Invention with the Viscose Fibers Described in EP 1 259 564 B1.

TABLE-US-00009 TABLE 8 Comparative overview of physical fiber data Bisfa Titer FFk FDk FFn FDn SFk KFk modulus [dtex] [cN/tex] [%] [cN/tex] [%] [cN/tex] [cN/tex] [cN/tex] EP 1 259 564 1.7 21.7 14.2 12.4 15.8 6.0 k.A. 2.9 Example 7 EP 1 259 564 1.7 23.7 16.9 14.1 18.5 6.5 k.A. 3.0 Example 8 EP 1 259 564 1.7 24.8 17.2 14.2 21.1 6.4 k.A. 2.9 Comparative Example 3 Ex. 1, 2.5% algae 1.71 31.3 10.6 18.6 12.1 k.A. k.A. 5.6 owc Fiber Ex. 1, 5% 1.79 31.3 11.4 17.2 12.1 k.A. k.A. 5.3 algae owc Fiber Ex. 2, 5% 1.83 23.5 11.2 13.2 12.2 k.A. k.A. 4.1 algae owc, 100 g/l dispersion Fiber Ex. 2, 5% 1.98 28.4 12.7 15.3 14.8 k.A. k.A. 4.5 algae owc, 50 g/l dispersion Fiber Ex. 2, 5% 1.89 29.1 11.8 17.4 13.2 k.A. k.A. 5.6 algae owc, 25 g/l dispersion. Fiber Ex. 3, 4% 1.75 27.4 13.5 k.A. k.A. k.A. k.A. k.A. algae owc Ex. 4, 1.8 27.6 13.1 14.5 13.7 8.8 17.6 4.2 fiber sample 1, 4% algae owc Ex. 4, 1.7 27.1 12.9 14.3 12.6 9.0 17.7 4.3 fiber sample 2, 4% algae owc Ex. 4, 1.7 26.3 12.7 13.5 12.3 9.0 18.6 4.4 fiber sample 3, 4% algae owc Ex. 4, 1.5 28.9 11.9 14.4 11.7 9.0 18.5 5.1 fiber sample 4, 4% algae owc Legend: owc: on weight of cellulose - proportion by weight on cellulose k.A.: no data

[0075] As can be seen in Table 8, with the exception of a fiber sample from Example 2, where, as mentioned above, good strengths were not obtained because of thread breakages, the fineness-related tear strength in the dry state is higher than 25 cN/tex in all fibers produced according to the invention with incorporated algal material, i.e., significantly higher than that of the viscose fibers from EP 1 259 564, Ex. 7 and 8, and even higher than that of the reference viscose fiber EP 1 259 564, Comparative Example 3.

[0076] In particular, the wet modulus according to BISFA, i.e., the tensile strength at 5% elongation in the wet state, is higher than 4.0 cN/tex in all fibers produced according to the invention with incorporated algal material, whereas the wet modulus does not exceed a value of 3.0 in the viscose types from EP 1 259 564.

[0077] As far as the wet modulus is concerned, all algae-incorporated types produced according to the modified viscose process comply with the minimum values as defined by BISFA for a modal fiber.

[0078] With respect to the dry strength, only fibers of Examples 1 and 2 (except Example 2.1 with 100 g/l algal dispersion) achieve the values required in the modal definition according to BISFA.

[0079] Accordingly, the viscose fibers modified according to the invention having incorporated algae are not modal fibers in the true sense of the word, but it is still possible to infer significantly improved use values in comparison to EP 1 259 564, Examples 7 and 8, from the substantially improved physical fiber properties. The connection between the wet modulus of fibers and the surface shrinkage of fabrics produced therefrom has long been known (Szeg, L., Faserforsch., Text. Techn. 21.10 (1970). Puchegger has confirmed this connection for viscose and modal fibers (Puchegger, F Lenzinger Ber., 55, 32-36 (1983) and Puchegger, F., Lenzinger Ber. 58, 94-99 (1985)).

[0080] In the following table, the process parameters of Examples 1-4 are summarized:

TABLE-US-00010 TABLE 9 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Viscose composition: Cellulose concentration 5.8 5.8 5.6 5.4 [% by weight] R18 content [%] 97.5 95 96 97 NaOH concentration in the viscose 6.2 6.1 6.5 6.7 [%] by weight Alkali ratio 0.9 1.0 0.9 0.8 (cellulose:NaOH, both g/l) CS.sub.2 in the viscose [% by weight on 37 39 36 38 cellulose] Modifier [% by weight] 3 3 4 4 Degree of ripeness (gamma value) 58 58 57 59 Spinning viscosity [falling-ball 96 80 95 82 seconds] Nozzle hole diameter 50 m 50 m 60 m 60 m Spinning bath composition: H.sub.2SO.sub.4 [g/l]: 75 73 74 72 Na.sub.2SO.sub.4 [g/l]: 128 123 125 120 ZnSO.sub.4 [g/l]: 60 65 65 60 T spinning bath [ C.]: 38 38 37 37 T secondary bath [ C.] 97 97 97 97 Final draw-off from the spinning 30 30 20 19 bath [m/min]