COMPOSITE LENGTHY BODY

Abstract

The invention relates to a method for manufacturing a lengthy body comprising high performance polyethylene fibres and a polymeric resin comprising the steps of applying an aqueous suspension of a polymeric resin to HPPE fibres, assembling the HPPE fibres, partially drying the aqueous suspension, optionally applying a temperature, tension and/or a pressure treatment to the lengthy body wherein the polymeric resin is a homopolymer or copolymer of ethylene and/or propylene. The invention further relates to lengthy bodies obtainable by said method and articles comprising the lengthy body such nets, round slings, splices, belts or synthetic chain links.

Claims

1. A method for manufacturing a lengthy body comprising high performance polyethylene fibres and a polymeric resin throughout the lengthy body comprising the steps of a) providing high performance polyethylene (HPPE) fibres b) applying an aqueous suspension of the polymeric resin to the HPPE fibres before, during or after; c) assembling the HPPE fibres to form a lengthy body d) at least partially drying the aqueous suspension of the polymeric resin applied in step b); to obtain a lengthy body comprising the high performance polyethylene fibres and the polymeric resin throughout the lengthy body upon completion of steps a), b), c) and d); e) optionally applying a temperature in the range from the melting temperature of the resin to 153? C. to the lengthy body of step c) before, during and/or after step d) to at least partially melt the polymeric resin; and f) optionally applying a pressure and/or a tension to the lengthy body obtained in step d) before, during and/or after step e) to at least partially compact and/or elongate the lengthy body, wherein the polymeric resin is a homopolymer or copolymer of ethylene and/or propylene and wherein said polymeric resin has a density as measured according to ISO1183 in the range from 860 to 930 kg/m3, a peak melting temperature in the range from 40 to 140? C. and a heat of fusion of at least 5 J/g.

2. The method according to claim 1 wherein the HPPE fibres are continuous filaments or staple fibres.

3. The method of claim 1 wherein the HPPE fibres are prepared by a melt spinning process, a gel spinning process or solid state powder compaction process.

4. The method according to claim 1 wherein the concentration of polymeric resin in the aqueous suspension is between 4 and 60 wt %, preferably between 5 and 50 wt %, most preferably between 6 and 40 wt %, whereby the weight percentage is the weight of polymeric resin in the total weight of aqueous suspension.

5. The method according to claim 1 wherein the HPPE fibres have a tenacity of at least 1.0 N/tex, preferably 1.5 N/tex, more preferably at least 1.8 N/tex.

6. The method according to claim 1 wherein the HPPE fibres comprise ultra high molecular weight polyethylene (UHMWPE), preferably the HPPE fibres substantially consist of UHMWPE.

7. The method according to claim 1 wherein the amount of polymeric resin in the lengthy body is between 1 and 25 wt %, preferably between 2 and 20 wt %, most preferably between 4 and 18 wt %, whereby the weight percentage is the weight of polymeric resin in the total weight of the lengthy body.

8. The method according to claim 1 wherein the density of the polymeric resin is in the range from 870 to 920 kg/m.sup.3 preferably from 875 to 910 kg/m.sup.3.

9. The method according to claim 1 wherein the peak melting temperature is in the range from 50 to 130? C., preferably in the range from 60 to 120? C.

10. The method according to claim 1 wherein the heat of fusion is at least 10 J/g, preferably at least 15 J/g, more preferably at least 20 J/g, even more preferably at least 30 J/g and most preferably at least 50 J/g.

11. A lengthy body obtainable by claim 1 comprising HPPE fibres and a polymeric resin throughout the lengthy body, wherein the polymeric resin is a homopolymer or copolymer of ethylene and/or propylene, wherein the polymeric resin has a density as measured according to ISO1183 in the range from 860 to 930 kg/m3, a melting temperature in the range from 40 to 140? C. and a heat of fusion of at least 5 J/g.

12. The lengthy body according to claim 11 wherein the lengthy body is a rope or a ribbon.

13. The lengthy body according to claim 11 containing at least 80 wt % of UHMWPE, whereby the weight percentage is the weight of UHMWPE in the total weight of the lengthy body.

14. An article comprising the lengthy body according to claim 11 wherein the article is a net, a round sling, a splice, a belt or a synthetic chain link.

15. Use of an aqueous suspension of a polymeric resin as a binder material for HPPE fibres wherein the polymeric resin is a homopolymer or copolymer of ethylene and/or propylene, wherein the polymeric resin has a density as measured according to ISO1183 in the range from 860 to 930 kg/m.sup.3, a peak melting temperature in the range from 40 to 140? C. and a heat of fusion of at least 5 J/g.

Description

EXAMPLE 1 AND COMPARATIVE EXPERIMENT A

[0057] 3 HPPE yarns (Dyneema? 1760 SK76, tenacity 35.5 cN/dtex, modulus 1245 cN/dtex) have been bundled and impregnated by dipping in a polyolefin suspension prepared by diluting suspension 1 with a tenfold amount of water. The wetted yarns were twisted with 160 turns per meter and fed through an oven with a length of 8.4 meters with an inlet speed of 5 m/s and an outlet speed of 6 m/s. The oven temperature was set at 153.6? C. The obtained dried monofilament-like product (Example 1) contained 3.5 wt % polyolefin resin and 96.5 wt % was fibrous material. For the comparative Experiment A, Example 1 was repeated without applying the suspension.

[0058] Table 1 reports the test results of Example 1 and Comparative experiment A. It is surprising that the sample of Example 1 has a tenacity of about 5% and modulus about 10% higher than the strengths of the reference sample, especially since the sample of Example 1 only comprises 96.5 wt % of loadbearing HPPE fibres

TABLE-US-00001 TABLE 1 Force at Young's Fracture Titer break Tenacity Modulus strain Fusion Sample [dtex] [N] [cN/dtex] [cN/dtex] [%] quality Example 1 4911 1048.9 21.4 592.9 3.61 excellent Comp. 4743 975.2 20.6 543.1 3.54 good Ex. A

COMPARATIVE EXAMPLE B

[0059] A rope having a diameter of 5 mm was produced from HPPE fibers (DSM Dyneema SK 78, 1760 dtex). The construction of the strands was 4?1760 dtex, 20 turns per meter S/Z. From the strands a rope was produced. The rope construction was a 12?1 strand braided rope with a 27 mm pitch. The average breaking strength of the rope was 18750 N.

[0060] The bend fatigue of the rope was tested. In this test the rope was bent over three free rolling sheaves each having a diameter of 50 mm. The three sheaves were arranged in a V-formation and the rope was placed over the sheaves in such a way that the rope has a bending zone at each of the sheaves. The rope was placed under load and cycled over the sheaves until the rope reached failure. In one machine cycle the sheaves were rotated in one direction and then in the opposite direction, thus passing the rope six times over a sheave in one machine cycle The stroke of this bending was 45 cm. The cycling period was 5 seconds per machine cycle. The force applied to the rope was 30% of the average breaking strength of the rope. Ropes according to comparative Example B failed on average [3] after 319 machine cycles.

COMPARATIVE EXPERIMENT C

[0061] Comparative Experiment B was repeated with the difference that the SK78, 1760 yarn had been coated by a coating process and a coating composition according to Example 1 of WO2011/015485, involving the dipping and drying in a 2 component coating followed by curing at 120? C. Ropes comprising the cross-linked silicone rubber coated yarn were subjected to the bending test of comparative B and failed on average [4] after 2048 cycles.

EXAMPLES 2 to 4

[0062] Comparative Experiment B was repeated with the difference that ropes have been constructed from 3 different yarns. For Example 2, the SK78, 1760 yarn was coated by dipping the yarn in suspension 3, followed by drying the yarn under tension in an oven at 60? C. for about 5 minutes. The obtained yarn had a polymeric resin content of about 10 wt %. For Examples 3 and 4 the suspension 3 was diluted with water in a 1:1 and a 1:3 ratio (suspension : water) respectively resulting after drying in coated yarns with a polymeric resin content of about 6 and 3 wt % respectively. All three yarns showed a surprising ease of handling, without fraying, stickiness or greasy appearance.

[0063] The ropes were subjected to the bending fatigue test described above and failed on average after [3] 1246, [4] 2286 and [4] 748 cycles for ropes 2, 3 and 4 respectively. Number between brackets express the number of tests performed with each type of rope.

[0064] The ropes according to examples 2 to 4 showed a remarkable stiffness and robust handling compared to ropes without a coating (Comp. Ex. B) or with a cross-linked silicone coating (Comp. Ex . C). The described performance in the continuous bending test came as a surprise to the inventors since such combination of bending fatigue properties and stiffness was not experienced before.

EXAMPLE 5 AND 6 AND COMPARATIVE EXPERIMENTS D, E AND F:

[0065] 16 ends of commercial yarn (Dyneema? 1760 SK78, tenacity 35.1 cN/dtex, modulus 1160 cN/dtex) have been braided to form a rope with a pitch length of about 2.5. Five knots have been prepared, each knot comprising 2 lengths of said rope knotted together according to FIG. 1. A first knot was wetted with suspension 1, and subsequently dried under ambient conditions (Example 5). A second knot was wetted with suspension 2, and subsequently dried under ambient conditions (Example 6). A third knot was wetted with suspension 4, and subsequently dried (Com. Ex. D). A fourth knot was left untreated (Comp. Ex. E).

[0066] A fifth knot (Comp. Ex. F) was prepared from a rope comparable to the one of Example 5 with the difference that the SK78-1760 yarn to prepare the rope was the cross-linked silicone coated yarn of Comparative Experiment C.

[0067] All knots were then tightened with 500 N, by pulling both ends of the first rope length (1) and (2) in the opposite direction to the two ends of the second rope length (3) and (4). After completion of the knot, one end (3) of the second rope length was cut at location (3a) in FIG. 2. Testing was performed by pulling the two ends (1) and (2) against the remaining end (4). The force at which the knot collapses due to slip is recorded as knot slippage force.

The results of the knot slippage force tests are presented below.

TABLE-US-00002 Knot slippage force Knot [N] Example 5 Suspension 1 1976 Example 6 Suspension 2 1836 Comp. Ex. D Suspension 4 635 Comp. Ex. E 279 Comp. Ex. F Silicone coating 187