POLYOLEFIN YARNS AND METHOD FOR MANUFACTURING

Abstract

The invention relates to a multifilament yarn having a tenacity of at least 30 cN/dtex, and comprising a plurality of spun ultrahigh molecular weight polyolefin filaments characterized in that the titer of any one of said spun filaments is at least 10 dtex.

Claims

1. A multifilament yarn having a tenacity of at least 12 cN/dtex, and comprising a plurality of spun ultrahigh molecular weight polyethylene filaments and a hard filler, characterized in that the titer of any one of said spun filaments is at least 10 dtex.

2. The yarn of claim 1, having a tenacity of at least 15 cN/dtex, preferably at least 17 cN/dtex.

3. The yarn of claim 1, having a filament titer of at least 12 dtex, preferably at least 14 dtex, more preferably at least 16 dtex and most preferably at least 18 dtex.

4. The yarn of claim 1, having a titer of at least 50 dtex, preferably at least 100 dtex, most preferably at least 400 dtex.

5. The yarn of claim 1, wherein the filaments comprise a hard filler having a Moh's hardness of at least 2.5.

6. The yarn of claim 1, wherein the hard filler include a glass filler, a mineral filler or a metal filler.

7. The yarn of claim 1, wherein the hard filler has a fiber-like shape with an average diameter of at most 20 microns, more preferably at most 15 microns, most preferably at most 10 microns.

8. The yarn of claim 1, further containing filaments manufactured from natural materials and preferably having discontinuous lengths said natural material being chosen from the group of materials consisting of cellulose, cotton, hemp, wool, silk, jute, sisal, cocoas and linen; with cotton being the preferred natural material.

9. A fabric comprising the yarn of claim 1.

10. A glove comprising the fabric according to claim 9.

11. A product chosen from the group of products consisting of fishing lines and fishing nets, ground nets, cargo nets and curtains, kite lines, dental floss, tennis racquet strings, canvas, nonwoven cloths and other types of fabrics, webbings, battery separators, capacitors, pressure vessels, hoses, (offshore) 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 such as skis, helmets, kayaks, canoes, bicycles and boat hulls and spars, speaker cones, high performance electrical insulation, radomes, sails and geotextiles, said product comprising the yarn of claim 1.

12. The spun UHMWPE monofilament of the multifilament yarn of claim 1 wherein the monofilament is a gel-spun monofilament with a tenacity of at least 30 cN/dtex and a titer of at least 10 dtex.

13. A method for manufacturing the yarn of claim 1, comprising in the following order the steps of: a. Providing a solution of ultrahigh molecular weight polyethylene and a hard filler, in a suitable solvent, preferably decaline; b. Forcing said solution through a die containing a plurality of apertures wherein the apertures issue said solution at a first speed to form a plurality of filaments containing said solution; each aperture having an exit with an exit diameter D.sub.ap.sup.exit; each of said filaments having a diameter D.sub.fil as measured at the exit of said capillary; c. Immersing said solution-containing-filaments into a cooling bath; preferably cooling water bath; and taking-up said immersed filaments onto a take-up roll rotating at a second speed; and d. Taking-out said filaments from the bath to form spun filaments, at least partially extracting the solvent and drawing said spun filaments in at least one drawing step before; during and/or after said extraction; wherein step b) is operated at a draw-down (DD.sub.op), defined as the ratio between the second speed and the first speed, of between 20% and 90% of a resonance draw-down DD.sub.res; wherein DD.sub.res is the ratio between the second speed and the first speed whereat D.sub.fil fluctuates per minute with a percentage of at least 25%, between a maximum value D.sub.fil.sup.max and a minimum value D.sub.fil.sup.min; wherein said percentage is calculated with Formula 1 $\begin{array}{cc}100\times \frac{D_{\mathrm{fil}}^{\max }-D_{\mathrm{fil}}^{\min }}{D_{\mathrm{fil}}^{\mathrm{avg}}}& \mathrm{Formula}.Math..Math.1\end{array}$ wherein D.sub.fil.sup.avg is the average value of D.sub.fil calculated from a number of at least 10 measurements recorded during a minute.

Description

EXAMPLES 1-4

[0064] A slurry was prepared from 9 wt % UHMWPE having an IV of about 20 dl/g in decalin and fed to a co-rotating twin screw extruder to transform the slurry into a solution. The extruder and spinning head was heated at a temperature of 185° C. The solution was forced through a die having 24 apertures with a rate of about 7.7 g/min (for examples 1 and 2) and 3.8 g/min (for examples 3 and 4) per aperture.

[0065] The apertures contained a conical contraction zone with an angle of 15° upstream to a capillary having a D.sub.ap.sup.exit of 3 mm and a length of about 8 mm.

[0066] The fluid filaments issued from the apertures entered an air gap and were taken-up at such rate that a draw ratio as shown in Table 1 below was applied in the air gap. The DD.sub.op at which the process is operated is the same as the drawing ratio in the air gap and is in all cases about 90% of the resonance draw down DD.sub.res.

[0067] Subsequently the fluid filaments entered a water bath where they were cooled and were taken up onto a take-up roll. Subsequently, they entered a first oven where they were drawn 8 times while the decalin evaporated.

[0068] From the first oven, the filaments entered a second oven where they were drawn with various draw ratios as shown in Table 1 below together with yarn's properties.

TABLE-US-00001 TABLE 1 EX 1 EX 2 EX 3 EX 4 Draw ratio air gap 16 16 14 14 Length air gap (mm) 15 15 7 7 Draw ratio 2.2 3.0 2.0 2.5 dtex yarn (dtex) 424 315 556 439 Tenacity yarn (cN/dtex) 29.4 29.8 25.2 28.3 Modulus yarn (cN/dtex) 1031 1241 897 1066 EAB yarn (%) 3.4 2.8 3.3 3.2 Filament titer (dtex) 18 13 23 18 Strength per filament (N) 5.3 3.9 5.8 5.1

EXAMPLES 5 AND 6

[0069] Example 1 was repeated with the difference that the yarn was further drawn in a third step at about 149° C. Two draw ratios are applied as shown in Table 2 below.

TABLE-US-00002 TABLE 2 EXAMPLE 5 EXAMPLE 6 Third step's draw ratio 1.8 2.2 dtex yarn (dtex) 290 213 Tenacity yarn (cN/dtex) 34.3 42.6 Modulus yarn (cN/dtex) 1390 1784 EAB yarn (%) 3.0 2.9 Filament titer (dtex) 12.1 8.9 Strength per filament (N) 4.1 3.8

EXAMPLE 7

[0070] The material of Example 1 was knit into a fabric with an aerial density of 260 g/m.sup.2 (stitch density 10 gauge). For reference, a fabric was knit of the same construction, using a commercially available yarn of 440 dTex containing 195 UHMWPE filaments, the yarn having a tenacity of about 31 cN/dtex and being sold by DSM Dyneema®, NL under the product name SK62.

[0071] Both fabrics were subjected to cut resistance testing according to standard EN388, as well as standard ASTM 1790-05 (both in duplicate). Similarly, fabrics were subjected to the Martindale (EN388) abrasion test, in which for each fabric type the numbers of cycles were determined where breakthrough observed. Results obtained are listed in the Table 3 below:

TABLE-US-00003 TABLE 3 Test Reference Example 7 EN 388 - Cut index 2.5 6.0 EN 388 - Cut index 3.7 6.1 ASTM F1790-05 Reference force 2.8 N 5.6 N ASTM F1790-05 Reference force 2.7 N 5.6 N EN 388 Abrasion breakthrough cycles 1140 cycles 3437 cycles

EXAMPLE 8

[0072] Example 1 was repeated; however, about 7% by weight of the total solution of a hard filler was added to the slurry prior to extrusion. The hard filler was mineral fibrils, i.e. a filler having fiber-like shape, sold under the trade name CF10ELS by Lapinus, NL. The resulting yarn had a titer of 410 dTex, a tenacity of about 18 cN/Dtex and a modulus of about 850 cN/dTex.

[0073] The yarn was knit into a fabric with aerial density of 260 g/m.sup.2 (Stitch density 10 gauge). For reference, a fabric was knit of the same construction, using a commercially available yarn of 440 dTex containing 130 UHMWPE filaments, the yarn having a tenacity of about 17 cN/dtex and containing the same type and amount of hard filler as the above.

[0074] Both fabrics were subjected to same cut resistance testing as detailed at example 7 above. The Martindale abrasion test was carried out 4 time for each fabric. Results obtained are listed in the Table 4 below:

TABLE-US-00004 TABLE 4 Test Reference Example 8 EN 388 - Cut index 15.69 28.15 EN 388 - Cut index — 24.82 ASTM F1790-05 Reference force 11.1 N 21.2 N ASTM F1790-05 Reference force 11.1 N 20.9 N EN 388 Abrasion breakthrough 400 cycles 1400 cycles EN 388 Abrasion breakthrough 459 cycles 1600 cycles EN 388 Abrasion breakthrough 691 cycles 1800 cycles EN 388 Abrasion breakthrough 1204 cycles 2200 cycles

EXAMPLES 9 AND 10

[0075] Example 1 was repeated, however, the fluid filaments were drawn about 19 times in the air gap with a throughput per aperture of 5.7 g/min. In the first oven they were stretched 6 times. The yarn was drawn in a second step with various draw ratios as shown in Table 4 below, together with yarn's properties.

TABLE-US-00005 TABLE 5 EXAMPLE 9 EXAMPLE 10 Draw ratio 3.0 4.0 Dtex yarn (dtex) 347 263 Tenacity yarn (cN/dtex) 30.9 34.7 Modulus yarn (cN/dtex) 1076 1269 EAB yarn (%) 3.5 3.4 Filament titer (dtex) 14 11 Strength per filament (N) 4.3 3.8

EXAMPLES 11 AND 14

[0076] Example 1 was repeated, however, the spinning head temperature was reduced to 175° C., the fluid filaments were drawn about 5.7 times in the air gap of a length of 4 mm and with a throughput per aperture of 7.7 g/min. The filaments were drawn in the first and a second step with various draw ratios as shown in Table 6 below, together with yarn's properties. From the 24 filaments exiting the spin plate a single filament was individually processed resulting in examples 11 to 13 while the remaining 23 filaments were processed as a 23 filament yarn. Only the corresponding 23 filament yarn of example 13 is reported as example 14 whereas the corresponding 23 filament yarns of examples 11 and 12 are not reported.

TABLE-US-00006 TABLE 6 EX 11 EX 12 EX 13 EX 14 Filaments per yarn 1 1 1 23 Draw ratio first oven 12 12 14 14 Draw ratio second oven 2.1 2.5 2.1 2.1 dtex yarn (dtex) 35 30 30 672 Tenacity yarn (cN/dtex) 32.6 34.2 29.2 27.5 Modulus yarn (cN/dtex) 1099 1189 1009 1042 EAB yarn (%) 3.5 3.5 3.3 3 Filament titer (dtex) 35 30 30 29 Strength per filament (N) 11.4 10.2 8.8 8.0