Method for producing a multifilament yarn

Abstract

The present invention relates to a method for producing a multifilament yarn from a melt of a copolymer of polyacrylicnitrile. The method is characterized in that a multifilament yarn is produced by means of pressing a melt of a copolymer through a spinning nozzle and is subsequently stretched at least tenfold. The present invention further relates to a correspondingly produced multifilament yarn.

Claims

1. A method for producing a multifilament yarn in which a melt of a copolymer of polyacrylonitrile (PAN), producible by a copolymerisation of 95 to 60% by mol of acrylonitrile with a) 5 to 20% by mol of at least one alkoxyalkylacrylate of the general formula I, ##STR00007## with R=C.sub.nH.sub.2n+1 and n=1-8 and m=1-8, b) 0 to 10% by mol of at least one alkylacrylate of the general formula II ##STR00008## with R′=C.sub.nH.sub.2n+1 and n=1-18, and c) 0 to 10% by mol of at least one vinyl ester of the general formula III ##STR00009## with R=C.sub.nH.sub.2n+1 and n=1-18, is spun in a melt spinning method by extruding a melt of the copolymer, wherein the melt of the copolymer is free of plasticising agents, through a spinneret which has a plurality of spinning holes to form a multifilament yarn and the multifilament yarn is stretched at least tenfold; and wherein the multifilament yarn is drawn off at a final drawing speed of at least 300 m/min; wherein the multifilament yarn comprises 50 to 5,000 individual filaments; or wherein the individual filaments forming the basis of the multifilament are set to a fineness of <10 dtex.

2. The method according to claim 1, wherein the multifilament yarn is stretched at least 20-fold.

3. The method according to claim 1, wherein the multifilament yarn is cooled before and/or during the stretching.

4. The method according to claim 1, wherein the formed multifilament yarn is drawn after the stretching.

5. The method according to claim 1, wherein the stretching and/or the drawing is effected by heated galettes, which are set to temperatures of at least 50° C.

6. The method according to claim 1, wherein the multifilament yarn is drawn off the spinneret with a nozzle drawing of <3,000.

7. The method according to claim 1, wherein stretching of the multifilament yarn is effected such that an orientation degree of the crystalline regions in the individual filaments forming the multifilament of ≥0.7 results.

8. The method according to claim 1, wherein the spinneret is at a temperature which is at least 10 K above the temperature of the melt of the copolymer.

9. The method according to claim 1, wherein the melt of the copolymer is set to a temperature of 120 to 300° C., and/or a zero shear viscosity, determined by a rheometer HAAKE RS 150 with plate-cone (1°) arrangement with a diameter of the measuring geometries of 20 mm and a gap opening of 0.052 mm, of <5,000 Pa.Math.s.

10. The method according to claim 1, wherein the individual filaments and/or the multifilament yarn formed from the individual filaments is cooled with a cooling medium.

11. The method according to claim 1, wherein the multifilament yarn is drawn off at a final drawing speed of 500 to 5,000 m/min.

12. The method according to claim 1, wherein the multifilament yarn comprises 500 to 4,000 individual filaments.

13. The method according to claim 1, wherein the individual filaments forming the basis of the multifilament are set to a fineness of 0.01 to 10 dtex.

14. The method according to claim 1, wherein the spinning holes have a round, oval, Y-shaped, star-shaped or n-angled geometry with 8≥n≥3 and/or a ratio of length to diameter of 1 to 20.

15. The method according to claim 1, wherein the diameter of the spinnerets is in the range of 10 to 1,000 μm.

16. The method according to claim 1, wherein the copolymer has a weight-average molar mass (Mw) in the range of 10,000 to 150,000 g/mol.

17. The method according to claim 1, wherein the copolymer has 90 to 78% by mol of acrylonitrile, 8 to 12% by mol of the comonomer a), 1 to 5% by mol of the comonomer b) and/or 1 to 5% by mol of the comonomer c).

Description

(1) The present invention is described in more detail with reference to the appended FIGURE.

(2) The FIGURE shows an apparatus, by way of an example, for implementing a method according to the invention. With this apparatus, the multifilament yarns according to the invention can likewise be produced.

(3) A melt of the copolymer is extruded through a spinneret 1 with a multiplicity of nozzle holes. The emerging individual filaments are thereby bundled to form a multifilament yarn. The resulting multifilament yarn is withdrawn via a take-down galette 4 through a cooling channel 2 at a withdrawal speed v.sub.w. At 3, an optional further preparation of the multifilament yarn can be effected. In the cooling channel 2, the multifilament yarn is supplied with cooling air (illustrated by arrows). Via the take-down galette 4, the stretching of the multifilament yarn can be adjusted.

(4) By means of subsequent drawing galettes 5 and 6, respectively a drawing factor x.sub.1 or x.sub.2 between the galettes 4 and 5 or 5 and 6 can be effected. The multifilament yarn is hence drawn even further between the galettes 4 and 5 and 5 and 6. The tension present on the multifilament yarn can be monitored by means of a tension sensor 7. Finally, the obtained multifilament yarn is wound onto a bobbin 8.