Ultra high molecular weight polyethylene multifilament yarn

Abstract

The invention relates to a multifilament yarn containing n filaments, wherein the filaments are obtained by spinning an ultra-high molecular weight polyethylene (UHMWPE), said yarn having a tenacity (Ten) as expressed in cN/dtex of Ten(cN/dtex)=f×n.sup.−0.05×dpf.sup.−0.15, wherein Ten is at least 39 cN/dtex, n is at least 25, f is a factor of at least 58 and dpf is the dtex per filament.

Claims

1. A multifilament yarn comprising a number n of filaments, wherein the filaments are obtained by spinning an ultra-high molecular weight polyethylene (UHMWPE), said yarn having a tenacity (Ten) as expressed in cN/dtex according to Formula 1:
Ten(cN/dtex)=f×n.sup.−0.05×dpf.sup.−0.15  (Formula 1) wherein Ten is at least 39 cN/dtex, n is at least 100, f is a factor of at least 58 and dpf is the dtex per filament.

2. The yarn according to claim 1 wherein the factor f is at least 60.0.

3. The yarn according to claim 1 wherein the number n of filaments is at least 200.

4. The yarn according to claim 1 wherein the dpf is at least 0.8.

5. The yarn according to claim 1, wherein the number n of filaments is at least 400.

6. The yarn according to claim 1, wherein the dpf is at least 1.3.

7. Ropes and cordages comprising the multifilament according to claim 1.

8. A reinforcing element suitable for reinforcing products, the element comprising the multifilament according to claim 1.

9. A medical device comprising the multifilament according to claim 1.

10. A composite article comprising the multifilament according to claim 1.

11. A composite article comprising at least one mono-layer which comprises the multifilament yarn according to claim 1.

12. A multi-layered composite article containing a plurality of unidirectional mono-layers, said mono-layers comprising the multifilament according to claim 1, wherein the direction of the yarn in each mono-layer is rotated with an angle with respect to the direction of the yarn in an adjacent mono-layer.

13. A product comprising the multifilament according to claim 1, wherein the product is selected from the group consisting of fishing lines and fishing nets, ground nets, cargo nets and curtains, kite lines, dental floss, tennis racquet strings, canvas, tent canvas, nonwoven cloths, webbings, battery separators, capacitors, pressure vessels, hoses, umbilical cables, electrical, optical fiber, and signal cables, automotive equipment, power transmission belts, building construction materials, cut and stab resistant and incision resistant articles, protective gloves, composite sports equipment, skis, helmets, kayaks, canoes, bicycles and boat hulls and spars, speaker cones, high performance electrical insulation, radomes, sails and geotextiles.

14. A panel comprising a plurality of sheets containing the multifilament yarn of claim 1, wherein each sheet comprises at least two monolayers.

15. The panel of claim 14, wherein the panel has an Eabs (J/[kg/m.sup.2]) of at least 170 against an AK47 FMJ MSC projectile, said Eabs being determined for an areal density of the panel of about 15.5 kg/m.sup.2.

16. The panel of claim 14, wherein the panel has an Eabs (J/[kg/m.sup.2]) of at least 370 against a 0.357 Magnum JSP projectile, said Eabs being determined for an areal density of the panel of about 3.1 Kg/m.sup.2.

17. The panel of claim 16, wherein the panel has an Eabs (J/[kg/m.sup.2]) against a 17 grain FSP projectile of at least 35, said Eabs being determined for an areal density of the panel of about 3.1 Kg/m.sup.2.

Description

EXAMPLES 1 and 2

(1) A 6 wt % slurry of a UHMWPE homopolymer powder having an elongational stress (ES) of about 0.68 N/mm.sup.2 was prepared in decalin and fed to a 42 mm co-rotating twin screw extruder heated at a temperature of 180° C., the extruder also being equipped with a gear-pump. In the extruder the slurry was transformed into a solution and the solution was issued through a spin plate having 50 spin holes with a rate of about 2.1 g/min per hole.

(2) The spin holes had an initial cylindrical channel of 2 mm diameter (D.sub.0) followed by a conical contraction with a cone angle of 15° into a cylindrical channel of 0.8 mm diameter (D.sub.n) and L.sub.n/D.sub.n of 10. The fluid filaments issued from the cylindrical channel entered an air gap having a length of 15 mm, and were taken-up at such rate that a draw down of about 4 was applied in the air gap. Subsequently they were cooled to room temperature in a water bath to form gel filaments, i.e. cooled filaments that contain a large amount of solvent.

(3) The filaments subsequently entered an oven. In the oven the filaments were further stretched 10 times at about 147° C. and the decalin evaporated. The yarn was drawn in a second step with various draw ratios as shown in Table 1 below.

(4) The yarn had the following properties:

(5) TABLE-US-00001 TABLE 1 Example 1 Example 2 draw ratio 3.5 3.9 Dtex yarn 78 68 Tenacity yarn 49 52.4 cN/dtex Modulus yarn 1798.7 1981.6 cN/dtex EAB yarn 3.4 3.2 dpf 1.56 1.36 dtex

EXAMPLE 3

(6) A 7 wt % slurry in decalin of a UHMWPE homopolymer powder having an ES of 0.68 N/mm.sup.2 was prepared and fed to a 133 mm co-rotating twin screw extruder heated at a temperature of 180° C., the extruder also being equipped with a gear-pump. In the extruder the slurry was transformed into a solution and the solution was issued through a spin plate having 780 spin holes with a rate of 2.4 g/min per hole.

(7) The spin holes had an initial cylindrical channel of 2 mm diameter (D.sub.0) followed by a conical contraction with a cone angle of 15° into a cylindrical channel of 0.8 mm diameter (D.sub.n) and L.sub.nD.sub.n of 10. The fluid filaments issued from the cylindrical channel entered an air gap of length 15 mm. The fluid filaments were taken-up at such rate that a draw down of 5 was applied to the fluid filaments in the air-gap and then cooled to room temperature in a water bath.

(8) The filaments subsequently entered an oven. In the oven the filaments were further stretched 9 times at about 147° C. and the decalin evaporated. The yarn was drawn in a second step at a temperature of 152° C. with a draw ratio of 4.7.

(9) The yarn had the following properties:

(10) TABLE-US-00002 TABLE 2 draw ratio 4.7 Dtex yarn 1024.0 Tenacity yarn 41.6 cN/dtex Modulus yarn 1613 cN/dtex EAB yarn 3.14 dpf 1.3 dtex

EXAMPLES 4 and 5

(11) A 7 wt % slurry in decalin of a UHMWPE homopolymer powder having an ES of 0.61 N/mm.sup.2 was prepared and fed to a 133 mm co-rotating twin screw extruder heated at a temperature of 180° C., the extruder also being equipped with a gear-pump. In the extruder the slurry was transformed into a solution and the solution was issued through a spin plate having 780 spin holes with a rate of 1.4 g/min per hole.

(12) The spin holes had an initial cylindrical channel of 2 mm diameter (D.sub.o) followed by a conical contraction with a cone angle of 15° into a cylindrical channel of 0.8 mm diameter (D.sub.n) and L.sub.n/D.sub.n of 10. The fluid filaments issued from the cylindrical channel entered an air gap of 15 mm. The fluid filaments were taken-up at such rate that a draw down of 6.2 was applied to the fluid filaments in the air-gap and then cooled in a water bath.

(13) The filaments subsequently entered an oven. In the oven the filaments were further stretched 10 times at about 147° C. and the decalin evaporated. The yarn was drawn in a second step at a temperature of 153° C. at various draw ratios.

(14) The yarn had the following properties:

(15) TABLE-US-00003 TABLE 3 Example 4 Example 5 draw ratio 4 5 Dtex yarn 869 687 dtex Tenacity yarn 41.6 45.4 cN/dtex Modulus yarn 1568 1772 cN/dtex EAB yarn 3.14 3.07 dpf 1.1 0.9 dtex

(16) To invention is further explained with the help of FIGURE. Therein it is represented the tenacity of the yarns versus f×n.sup.0.05×dpf.sup.−0.15. The FIGURE clearly show that the yarns of the invention (represented by o) as manufactured according to Examples 1-5 have a higher tensile strength than the known commercial yarns or the best yarns reported in WO 2005066401 (all represented by •) and in U.S. Pat. No. 6,969,553 B1 (represented by .box-tangle-solidup.) at a given filament count and dpf. Therefore, the inventors were able to manufactured for the first time yarns having a large number of high dtex filaments while surprisingly also increasing the tenacity of the yarns. In FIGURE, the dotted lines represents Formula 1 “Ten(cN/dtex)=f×n.sup.−0.05×dpf.sup.−0.15” wherein f was 58.6, 62.5, 64.0 and 67.0, respectively.

EXAMPLE 6

(17) A unidirectional monolayer was formed from a plurality of the yarns aligned to run in parallel. The yarns had a dtex of about 1220.0; a tenacity of about 39.7 cN/dtex; a modulus of about 1450 cN/dtex and a dtex per filament of about 1.5. The yarns were held together by about 17 mass % (of the total mass of the monolayer) of an elastomeric matrix material based on Kraton® rubber. A sheet was formed using 4 stacked unidirectional monolayers in a 0-90° orientation. The areal density of resulting sheet was 212 gr/m.sup.2.

(18) The yarns were made according to Example 3, with the difference that the solution was issued at a rate of 1.7 g/min/hole; a draw down of about 6.5 was used; the yarn was drawn 8 times at about 147° C. in the first step and 3.8 times in a second step at a temperature of about 152.5° C.

(19) A number of such sheets were pressed together to form a rigid panel with an areal density of 15.5 kg/m.sup.2. The V50 of the panel for an AK47 FMJ MSC bullet was determined to be about 891 ms, corresponding to an E.sub.abs of about 242 J.m.sup.2/kg. The data is included in Table 4.

(20) Comparative Experiment 1 (CE1)

(21) Example 6 was repeated with the difference that commercial UHMWPE yarns sold by DSM Dyneema® B.V., the Netherlands, and known as SK76 (1500 dtex; tenacity 36.5 cN/dtex; modulus 134 N/tex) were used instead of the yarns of Example 3. A monolayer contained about 16 mass % of matrix. The areal density of the sheet was about 233 gr/m.sup.2 and the areal density of the pressed panel was about 16.0 Kg/m.sup.2. The V50 of the panel for an AK47 FMJ MSC bullet was determined to be about 814 ms, corresponding to an E.sub.abs of about 166 J.m.sup.2/kg. The data is included in Table 4.

EXAMPLE 7

(22) A number of sheets as in Example 6 were made, with the difference that each sheet also contained two 7 micrometers thick LDPE films sandwiching the stack of 4 monolayers. The areal density of such a sheet was about 157 gr/m.sup.2. Three flexible panels, two having an areal density of about 3.1 Kg/m.sup.2 and one having an areal density of about 4.9 Kg/m.sup.2, were formed by assembling a number of flexible sheets. The sheets were not pressed. The panels having 3.1 Kg/m.sup.2 were shot with a 0.357 Magnum JSP bullet and with a 9 mm FMJ Parabellum bullet. The panel having 4.9 Kg/m.sup.2 was shot with a 17 grain FSP. The data is included in Table 4.

(23) Comparative Experiment 1 (CE2)

(24) Example 7 was repeated with the difference that commercial UHMWPE yarns sold by Dyneema® B.V., the Netherlands, and known as SK76 were used instead of the yarns of Example 3 and a sheet only contained two monolayers. The areal density of such a sheet was about 132 gr/m.sup.2. The data is reported in Table 4.

(25) TABLE-US-00004 TABLE 4 Ex- am- AD.sub.sheet AD.sub.panel matrix BFD V50 Eabs ple gr/m.sup.2 Kg/m.sup.2 % mm threat m/s J/[kg/m.sup.2] 6 212 15.5 16.7 — AK47 891.3 242 CE1 233 16.0 16 — AK47 814 166 7 157 3.1 17 34 Magnum 522.8 453 3.1 9 mm 534.4 373 4.9 FSP1.1 611.6 41 CE2 132 3.0 17 40 Magnum 457 358 3.0 9 mm 400 218 4.9 FSP1.1 535 33

(26) It can be easily observed from Table 4 that the panels based on the yarns of the invention show a noticeable improvement of their ballistic properties. Therefore, the invention relates to a panel comprising a plurality of sheets containing the yarn of the invention. Preferably, each sheet comprises a plurality of monolayers, preferably at least 2 monolayers, more preferably at least 4 monolayers. Preferably each sheet comprises at most 8 monolayers, more preferably at most 6 monolayers. Preferably the yarns in the sheets or in the monolayers are arranged unidirectionally, i.e. they run along a common direction. Preferably the sheets or the monolayers also contains a matrix material typically used to stabilize the handling thereof in an amount of at most 25 mass % based on the total weight of the panel, more preferably at most 21 mass %, even preferably at most 19 mass %, most preferably at most 17 mass %. Preferably, the amount of said matrix material is at least 5 mass %, more preferably at least 10 mass %, most preferably at least 15 mass %. In a preferred embodiment, the panel comprises a number of sheets, each sheet comprising a stack of monolayers and further comprising two polymeric films, preferably polyethylene films, more preferably LDPE films, sandwiching said stack of monolayers.

(27) In a preferred embodiment, the panel of the invention is a rigid panel having preferably an Eabs (J/[kg/m.sup.2]) of at least 170 against an AK47 FMJ MSC projectile, more preferably of at least 190, even more preferably at least 210, most preferably at least 230, said Eabs being determined for an areal density of the panel of about 15.5 kg/m.sup.2. Preferably, the article of the invention is a rigid article. By a rigid panel is herein understood an article having a flexural strength of preferably at least 10 MPa, more preferably of at least 20 MPa, most preferably of at least 40 MPa as measured before impacts. The flexural strength can be measured using a methodology as described at pg. 14 of WO 2012032082. A rigid panel can be obtained by subjecting a stack of sheets comprising fibers, preferably unidirectionally aligned yarns containing fibers, to a pressure of at least 50 bars, more preferably at least 70 bars, most preferably at least 90 bars; and to a temperature preferably below the melting temperature of said fibers, more preferably within the range of 20 degrees below said melting temperature. The melting temperature of the fibers can be determined by DSC using a methodology as described at pg. 13 of WO 2009056286.

(28) In another preferred embodiment, the panel of the invention is a flexible panel having preferably an Eabs (J/[kg/m.sup.2]) of at least 370 against a 0.357 Magnum JSP projectile, more preferably of at least 390, even more preferably at least 410, yet even preferably at least 430, most preferably at least 450; said Eabs being determined for a flexible panel having an areal density of about 3.1 Kg/m.sup.2. By flexible panel is herein understood a panel manufactured by assembling together a plurality of sheets without compressing. Stitching or (spot)-gluing the sheets together may be utilized to provide the panel with better handleability. Alternatively, the sheets may be hold together by a bag. Preferably, the flexible panel has an Eabs (J[kg/m.sup.2]) against an 9 mm FMJ Parabellum projectile of at least 220, more preferably at least 250, even more preferably at least 280, yet even more preferably at least 310, yet even more preferably at least 340, most preferably at least 370; said Eabs being determined for a flexible panel having an areal density of about 3.1 Kg/m.sup.2. Preferably, the flexible panel has an Eabs (J[kg/m.sup.2]) against a 17 grain FSP projectile of at least 35, more preferably at least 38, most preferably at least 41; said Eabs being determined for a flexible panel having an areal density of about 3.1 Kg/m.sup.2.

EXAMPLE 8

(29) A rope was braided from the yarns of the invention. It was observed that when subjected to bending, the bending performance of such a rope was improved with 38% in comparison with a similar rope braided from known yarns of Dyneema® SK75 fibers. The bending performance of the rope braided from the yarns of the invention was also improved with about 10% over a rope braided from yarns as reported in WO 2005066401.