High-performance polyethylene multifilament yarn
Processes for making high-performance polyethylene multi-filament yarn are disclosed which include the steps of a) making a solution of ultra-high molar mass polyethylene in a solvent; b) spinning of the solution through a spinplate containing at least 5 spinholes into an air-gap to form fluid filaments, while applying a draw ratio DR fluid ; c) cooling the fluid filaments to form solvent-containing gel filaments; d) removing at least partly the solvent from the filaments; and e) drawing the filaments in at least one step before, during and/or after said solvent removing, while applying a draw ratio DR solid of at least 4, wherein in step b) each spinhole comprises a contraction zone of specific dimension and a downstream zone of diameter Dn and length Dn with Ln/Dn of from 0 to at most 25, to result in a draw ratio DR fluid =DR sp *DR ag of at least 150, wherein DR sp is the draw ratio in the spinholes and DR ag is the draw ratio in the air-gap, with DR sp being greater than 1 and DR ag at least 1. High-performance polyethylene multifilament yarn, and semi-finished or end-use products containing said yarn, especially to ropes and ballistic-resistant composites, are also disclosed.
1. A preformed sheet comprising four mono-layers, each mono-layer comprising polyethylene filaments obtained from multifilament polyethylene yarn, the polyethylene having an IV of between 8 and 40 dl/g as measured on decalin solutions at 135° C., wherein the filaments in the mono-layers are spread unidirectionally, and wherein a direction of the filaments in each of the mono-layers is rotated with respect to a direction of the filaments in an adjacent layer, and wherein the preformed sheet exhibits a specific energy absorption of more than 265 and at most 479 J·kg/m2 against a 9*19 mm FMJ Parabellum FMJ bullet, as measured on panels assembled from a plurality of the preformed sheets having an areal density of 2.0 kg/m2.
2. The preformed sheet of claim 1 , wherein the preformed sheet exhibits a specific energy absorption of between 280 and 479 J·kg/m 2 against a 9*19 mm FMJ Parabellum FMJ bullet.
3. The preformed sheet of claim 1 , wherein the preformed sheet exhibits a specific energy absorption of between 291 and 479 J·kg/m 2 against a 9*19 mm FMJ Parabellum FMJ bullet.
4. The preformed sheet of claim 1 , wherein the preformed sheet exhibits a specific energy absorption of between 300 and 479 J·kg/m 2 against a 9*19 mm FMJ Parabellum FMJ bullet.
5. The preformed sheet of claim 1 , wherein the preformed sheet exhibits a specific energy absorption of between 280 and 442 J·kg/m 2 against a 9*19 mm FMJ Parabellum FMJ bullet.
6. The preformed sheet of claim 1 , wherein the preformed sheet exhibits a specific energy absorption of between 291 and 442 J·kg/m 2 against a 9*19 mm FMJ Parabellum FMJ bullet.
7. The preformed sheet of claim 1 , wherein the preformed sheet exhibits a specific energy absorption of between 300 and 442 J·kg/m 2 against a 9*19 mm FMJ Parabellum FMJ bullet.
8. The preformed sheet of claim 1 , wherein the preformed sheet exhibits a specific energy absorption of between 291 and 391 J·kg/m 2 against a 9*19 mm FMJ Parabellum FMJ bullet.
9. The preformed sheet of claim 1 , wherein each of the mono-layers has an areal density of between 18.4 and 65.5 g/m 2 .
10. The preformed sheet of claim 1 , wherein each of the mono-layers has an areal density of between 18.4 and 58.5 g/m 2 .
11. The preformed sheet of claim 1 , wherein each of the mono-layers has an areal density of between 18.4 and 40.3 g/m 2 .
12. The preformed sheet of claim 1 , wherein each of the mono-layers has an areal density of between 20.2 and 40.3 g/m 2 .
13. The preformed sheet of claim 1 , wherein each of the mono-layers has an areal density of between 22.2 and 37.6 g/m 2 .
14. The preformed sheet of claim 1 , wherein the preformed sheet comprises a binder in an amount less than 30 mass % based on the mass of the preformed sheet.
15. The preformed sheet of claim 14 , wherein the amount of the binder is less than 20 mass % based on the mass of the preformed sheet.
16. The preformed sheet of claim 14 , wherein the amount of the binder is less than 15 mass % based on the mass of the preformed sheet.
17. The preformed sheet of claim 14 , wherein the amount of the binder is between 10 and 23 mass % based on the mass of the preformed sheet.
18. The preformed sheet of claim 14 , wherein the amount of the binder is between 10 and 18 mass % based on the mass of the preformed sheet.
19. The preformed sheet of claim 1 , wherein the mono-layers have an areal density of between 18.4 and 65.5 g/m 2 and the preformed sheet comprises a binder in an amount between 10 and 23 mass %, based on the mass of the preformed sheet.
20. The preformed sheet of claim 19 , wherein the mono-layers have an areal density of between 18.4 and 40.3 g/m 2 and the preformed sheet comprises a binder in an amount between 10 and 23 mass %, based on the mass of the preformed sheet.
21. The preformed sheet of claim 19 , wherein the mono-layers have an areal density of between 18.4 and 40.3 g/m 2 and the preformed sheet comprises a binder in an amount between 10 and 18 mass %, based on the mass of the preformed sheet.
22. The preformed sheet of claim 19 , wherein the mono-layers have an areal density of between 20.2 and 40.3 g/m 2 and the preformed sheet comprises a binder in an amount between 10 and 23 mass %, based on the mass of the preformed sheet.
23. The preformed sheet of claim 19 , wherein the mono-layers have an areal density of between 22.2 and 37.6 g/m 2 and the preformed sheet comprises a binder in an amount between 10 and 23 mass %, based on the mass of the preformed sheet.
24. The preformed sheet according to claim 1 , wherein the polyethylene has an IV of between 10 and 30 dl/g.
25. The preformed sheet according to claim 24 , wherein the polyethylene has an IV of between 12 and 28 dl/g.
26. The preformed sheet according to claim 24 , wherein the polyethylene has an IV of between 15 and 25 dl/g.
27. The preformed sheet according to claim 1 , wherein said sheet further comprises at least one film layer.
28. The preformed sheet according to claim 27 , wherein said sheet further comprises a film layer on both of its outer sides.
29. The preformed sheet according to claim 27 , wherein said film is a polyethylene film having a weight of about 7 g/m 2 .
30. A ballistic-resistant article comprising the preformed sheet according to claim 1 .