A PROCESS FOR THE MANUFACTURE OF A PRECURSOR YARN

Abstract

The present invention relates to a method for manufacturing precursor yarn comprising lignin, which may be further processed into intermediate carbon fibers and finally also carbon fibers. It also relates to carbon fibers and uses of said fibers. Said method involves applying a water-free spin finish.

Claims

1. A method for manufacturing a precursor yarn comprising lignin, comprising the following steps: a) providing cellulose and/or a cellulose derivative, b) providing lignin and/or a lignin derivative, c) dissolution of said components followed by subsequent mixing thus providing a dope, d) performing a spinning of the dope to a precursor material, e) applying a water-free spin finish on said precursor material, and f) drying of said precursor material, thus providing a precursor yarn comprising lignin.

2. A method according to claim 1 wherein the spinning in step d) is performed through a solution spinning or wet-spinning.

3. A method according to claim 1 wherein the application in step e) is performed by using a bath, oiler stone or dip roller or a combination thereof.

4. A method according to claim 1 wherein the water-free spin finish in step e) comprises at least one organic solvent with a boiling point lower than 130 C.

5. A method according to claim 4 wherein the water-free spin finish in step e) comprises one or more aprotic polar solvents with a dipole moment in the range of from 510.sup.30 Cm to 1010.sup.30 Cm, and/or one or more protic polar solvents with a dipole moment in the range of from 510.sup.30 Cm to 810.sup.30 Cm.

6. A method according to claim 4 wherein the protic polar solvent has a structure as shown below, wherein at least one of R1, R2 and R3 always is a hydroxyl group, and R1, R2 and R3 are as follows: ##STR00003##

7. A method according to claim 4 wherein the aprotic polar solvent is selected from the groups of ketoalkyl or ketoalkoxy compounds, or alternatively is comprised of cyclic structures of 5- and 6-rings containing heteroatoms as set out below and have a structure as shown below, wherein R1, R2, R3 and R4, and W, X, Y, Z are as follows: ##STR00004##

8. A method according to claim 1 wherein the water-free spin finish additionally contains one or more anti-static agents.

9. A method according to claim 1 wherein the water-free spin finish additionally is mixed with a water-containing spin finish within the range of from 1:10 to 10:1.

10. A method according to claim 1 wherein the temperature which is applied during the drying step f) does not exceed 150 C.

11. A method according to claim 1 wherein the water-free spin finish is applied before drying, after drying or before and after drying.

12. (canceled)

13. A precursor yarn comprising lignin obtainable by the method according to claim 1.

14. A method for manufacturing a stabilized carbon fibre comprising the following steps: g) providing a precursor yarn comprising lignin according to claim 13, and h) performing a stabilization, thus providing a stabilized carbon fibre.

15. A method according to claim 14 wherein the stabilization is performed at a temperature from about 100 to about 450 C., wherein the stabilization is done at a residence time of from 10 to 180 minutes.

16. A stabilized carbon fibre obtainable by the method according to claim 14.

17. A method according to claim 14 comprising the following additional step: i) performing a stretch-pre-carbonization, thus providing a highly oriented intermediate carbon fiber.

18. The method according to claim 17 wherein the stretch-pre-carbonization is realized by stretching the stabilized fiber up to 10-fold at a temperature below 1300 C.

19. An intermediate carbon fibre obtainable by the method according to claim 17.

20. A method for manufacturing a carbon fiber comprising the following steps: j) a stabilized carbon fibre according to claim 16 and k) performing a carbonization step, thus providing a carbon fiber.

21. A method according to claim 20 wherein the carbonization is performed at a temperature from 900 to 2000 C., in an inert gas.

22. A carbon fiber obtainable by the method according to claim 20.

23. A carbon fiber having an E-Modulus of from about 870 to about 1480 cN/tex, and a tenacity of from about 16 to about 36.5 cN/tex.

24. A carbon fiber according to claim 23 obtainable by the method according to claim 20.

25. (canceled)

26. A method according to claim 1 wherein the spinning in step d) is performed through air-gap spinning or dry jet-wet spinning.

27. A method according to claim 1 wherein the water-free spin finish in step e) comprises at least one organic solvent with a boiling point lower than 130 C., selected from the group of protic polar solvents, the group of aprotic polar solvents, or combinations thereof.

28. A method according to claim 4 wherein the water-free spin finish in step e) comprises one or more aprotic polar solvents with a dipole moment in the range of from 510.sup.30 Cm to 1010.sup.30 Cm, namely acetone or ethyl acetate, and/or one or more protic polar solvents with a dipole moment in the range of from 510.sup.+Cm to 810.sup.30 Cm, namely ethanol, propanol and iso-propanol.

29. A method according to claim 1 wherein the water-free spin finish additionally contains one or more anti-friction agents.

30. A method according to claim 1 wherein the water-free spin finish additionally is mixed with a water-containing spin finish within the range of from 1:5 to 5:1.

31. A method according to claim 1 wherein the water-free spin finish additionally is mixed with a water-containing spin finish within the range of 1:1.

32. A method according to claim 14 wherein the stabilization is performed at a temperature from about 200 to about 300 C., wherein the stabilization is done at a residence time of from 10 to 180 minutes.

33. A method according to claim 14 wherein the stabilization is performed at a temperature from about 220 to about 280 C. wherein the stabilization is done at a residence time of from 10 to 180 minutes.

34. A method according to claim 14 wherein the stabilization is performed at a temperature from about 100 to about 450 C., wherein the stabilization is done at a residence time of from 20 to 80 minutes.

35. A method according to claim 14 wherein the stabilization is performed at a temperature from about 200 to about 300 C., wherein the stabilization is done at a residence time of from 20 to 80 minutes.

36. A method according to claim 14 wherein the stabilization is performed at a temperature from about 220 to about 280 C. wherein the stabilization is done at a residence time of from 20 to 80 minutes.

37. The method according to claim 17 wherein the stretch-pre-carbonization is realized by stretching the stabilized fiber up to 10-fold at a temperature below 1100 C.

38. The method according to claim 17 wherein the stretch-pre-carbonization is realized by stretching the stabilized fiber up to 10-fold at a temperature below 1000 C.

39. A method according to claim 20 wherein the carbonization is performed at a temperature from 1200 to 1800 C. in an inert gas.

40. A method for manufacturing a carbon fiber comprising the following steps: j) an intermediate carbon fiber according to claim 19 and k) performing a carbonization step, thus providing a carbon fiber.

Description

FIGURE

[0055] FIG. 1 discloses SEM-images of the surface of lignin containing precursors.

[0056] Left: Surface defect of lignin containing precursor treated with a commercial spin finish (example 1). The defects were caused by stickiness followed by mechanical disruption during winding

[0057] Middle: Perfect surface of single lignin-containing precursor filament that was treated by applying acetone as spinning oil (example 2)

[0058] Right: A SEM image displaying a multifilament bundle of lignin-containing filaments from example 2 that clearly shows complete separation of the individual filaments.

EXAMPLES

Example 1

[0059] An endless, continuous yarn consisting of 70 filaments and comprised of cellulose and lignin was produced according to the method described in patent publication WO2012156441A1. Specifically, 7.7% wt cellulose and 11.6% wt lignin were mixed with N-methylmorpholine-N-oxide hydrate and heated at 90 C. at 50 mbar until a NMMO content of at least 87% was attained and the dope was formed. In an air-gap spinning apparatus the dope was transferred to the spinning pump by a single screw-extruder. The throughput and drawing from the nozzle were adjusted so that total fineness of the final single-filament was 7-8 dtex. The dope was spun using a nozzle having 70 holes with diameters of 0.15 mm. A 40 mm air gap was realized between the nozzle and the coagulation bath. A constant air flow in the air gap was supplied to discharged dope. The multifilament was coagulated in the coagulation bath and passed through a washing bath filled with hot water followed by washing with distilled water using three Nelson Type rollers. The precursor was then treated with Stoko MW, a commercial spin finish for man-made cellulosic fibers from the company Stockhausen & Co. The spin finish was applied onto the yarn by an oiler stone. The amount spinning oil was set to be 35 cm.sup.3/min by a gear pump. The coated precursor was then dried at 80 C. in a 2-stage drying roll to obtain lignin-cellulose containing precursors. The resulting endless filament yarn contained a large number of junctions where single filaments stick together. In the following winding process those filament-filament junctions are disrupted causing fiber breakages (FIG. 1, left).

Example 2

[0060] An endless precursor yarn with 70 filaments was manufactured analogously to the method described in example 1 with the exception that prior to the drying stage the yarn was treated with acetone as spin finish instead of Stoko MW. All other processing steps were similar to those described in example 1. Surprisingly, this treatment resulted in an endless filament yarn, free of single filament adhesion, that could be wound and unwound with no fiber breakages (FIG. 1, middle and right). 3) The multi-filament lignin containing precursor yarns from examples 1 and 2 were converted into carbon fibers by applying a stabilization regime up to 250 C. by a heating rate of 50 C./min for a total time of 90 min followed by the carbonization which was performed by reaching a final temperature of 1600 C. by a heating rate of 27 C./min.

[0061] Surprisingly, the carbon fiber produced from precursor yarn in example 2 exhibited significantly better mechanical properties compared to those of the corresponding carbon fiber produced from precursor yarn in example 1 with 175% higher tenacity and 150% higher E-Modulus.

Example 3

[0062] An endless precursor yarn with 70 filaments was manufactured analogously to the method described in example 1 with the exception that prior to the drying stage the yarn was treated with ethyl acetate as spin finish instead of Stoko MW. All other processing steps were similar to those described in example 1.

[0063] Surprisingly, this treatment resulted in an endless filament yarn, nearly free of single filament adhesion, which could be wound and unwound with almost no fiber breakages. The multi-filament lignin containing precursor yarns from examples 1 and 3 were converted into carbon fibers by applying a stabilization regime up to 250 C. by a heating rate of 50 C./min for a total time of 90 min followed by the carbonization which was performed by reaching a final temperature of 1600 C. by a heating rate of 27 C./min.

[0064] Surprisingly, the carbon fiber produced from precursor yarn in example 3 exhibited significantly better mechanical properties compared to those of the corresponding carbon fiber produced from precursor yarn in example 1 with 225% higher tenacity (36.5 cN/tex) and 170% higher E-Modulus (1480 cN/tex).

Example 4

[0065] (additional example) An endless precursor yarn with 70 filaments was manufactured analogously to the method described in example 1 with the exception that prior to the drying stage the yarn was treated with ethanol as spin finish instead of Stoko MW. All other processing steps were similar to those described in example 1.

[0066] This treatment resulted in an endless filament yarn, with an increased number of single filament adhesion, which could hardly be wound and unwound with significant number of fiber breakages. The multi-filament lignin containing precursor yarns from examples 1 and 4 were converted into carbon fibers by applying a stabilization regime up to 250 C. by a heating rate of 50 C./min for a total time of 90 min followed by the carbonization which was performed by reaching a final temperature of 1600 C. by a heating rate of 27 C./min.

[0067] The carbon fiber produced from precursor yarn in example 4 exhibited significantly lower mechanical properties compared to those of the corresponding carbon fiber produced from precursor yarn in example 1 with 60% less tenacity and 20% lower E-Modulus (6.5 cN/tex and 700 cN/tex, respectively).

[0068] Various embodiments of the present invention have been described above but a person skilled in the art realizes further minor alterations, which would fall into the scope of the present invention. The breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents. For example, any of the above-noted methods may be combined with other known methods. Other aspects, advantages and modifications within the scope of the invention will be apparent to those skilled in the art to which the invention pertains.

REFERENCES

[0069] [1] Kadla, J. F., et al. Carbon 40 (15), 2002, p. 2913-2920

[0070] [2] Kubo Y., et al., Carbon 36 (7-8), 1998, p. 1119-1124

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[0072] [4] Uraki, Y. et al., Holzforschung 49 (4), 1995, p.343-350

[0073] [5] F. E. Brauns and D. A. Brauns, The Chemistry of Lignin, Supplement Volume, Academic Press, New York, 1960, p. 173; D. A. I. Goring, in Lignins, K. V. Sarkanen and C. H. Ludwig, Eds., Interscience, New York, 1971, p. 695.

[0074] [6] P. R. Gupta, A. Rezanowich, and D. A. I. Goring, Pulp Paper Mag. Can., 63, T-21 (1962).

[0075] [7] D. A. I. Goring, Pulp Paper Mag. Can., 64, T-517 (1963).

[0076] [8] G. Husman, Development and Commercialization of a Novel Low-Cost Carbon Fiber, Zoltek, http://energy.gov/sites/prod/files/2014/07/f17/1m048_busman_2014_o.pdf, 2014