Hybrid chain link

Abstract

The present invention relates to a chain link comprising a strip comprising a longitudinal core section and at least two longitudinal edge sections, wherein the thickness of the core section is higher than the thickness of the edge sections, preferably the strip comprising warp yarn A and warp yarn B, the titer of warp yarn A being higher than the titer of warp yarn B, and wherein the concentration of warp yarn A in the core section is higher than the concentration of yarn A in the edge sections of the strip and the concentration of warp yarn B in the edge sections is higher than the concentration of warp yarn B in the core section of the strip. The invention also relates to a chain comprising said chain link and to the use of said chain in different applications.

Claims

1. A chain link comprising a strip, wherein the strip includes a longitudinal core section and at least two longitudinal edge sections, and wherein the core section has a thickness which is greater than a thickness of the at least two edge sections, and wherein the strip comprises warp yarns containing warp yarn A and warp yarn B, wherein the warp yarn A has a titer which is greater than a titer of the warp yarn B, and wherein the warp yarn A is present in the core section at a concentration which is greater than a concentration of the warp yarn A in the edge sections of the strip, and wherein the warp yarn B is present in the edge sections at a concentration which is greater than the concentration of the warp yarn B in the core section of the strip.

2. The chain link according to claim 1, further comprising a warp yarn C, wherein the titer of the warp yarn A is greater than the titer of warp yarn B, and wherein the titer of the warp yarn B is greater than a titer of the warp yarn C, and wherein the warp yarns B and C are present in the edge sections at a concentration which is greater than a concentration of the warp yarns B and C in the core section of the strip.

3. The chain link according to claim 2, wherein the concentration of the warp yarn C in the longitudinal edge sections is less than the concentration of the warp yarn B in the longitudinal edge sections.

4. The chain link of claim 2, wherein warp yarn C is located at outmost regions of the at least two longitudinal edge sections of the strip.

5. The chain link of claim 2, wherein, the titer of warp yarn C is in the range of from 500 dtex to 7500 dtex.

6. The chain link of claim 5, wherein, the titer of warp yarn C is in the range between 800 dtex and 2000 dtex.

7. The chain link according to claim 1, wherein the warp yarns comprise a high performance polymeric yarn.

8. The chain link according to claim 7, wherein the high performance polymeric yarn is a high performance polyolefin yarn.

9. The chain link according to claim 8, wherein the high performance polymeric yarn is an ultrahigh molecular weight polyethylene (UHMWPE) yarn.

10. The chain link of claim 1, wherein the concentration of the warp yarn A in the core section is in a range of 50 wt % to 100 wt %, based on the total warp yarn weight of the core section.

11. The chain link of claim 1, wherein the concentration of the warp yarn A in each of the longitudinal edge sections is in a range of 0 wt % to 100 wt %, based on the total warp yarn weight of each longitudinal edge section.

12. The chain link according to claim 1, wherein the strip has a longitudinal axis and forms a plurality of convolutions, wherein each convolution of the strip comprising a twist along the longitudinal axis of the strip, the twist being an odd multiple of 180 degrees.

13. The chain link of claim 12, wherein the chain link comprises at least 4 convolutions.

14. The chain link of claim 1, wherein the warp yarns have different minimum creep rates, measured at a tension of 900 MPa and a temperature of 30 C.

15. The chain link of claim 14, wherein the warp yarns A and B have different minimum creep rates, measured at a tension of 900 MPa and a temperature of 30 C.

16. The chain link of claim 1, wherein the warp yarns in the at least two longitudinal edge sections have a length which is greater than a length of the warp yarn in the core section of the strip.

17. The chain link according to claim 1, wherein the strip is a woven structure.

18. The chain link of claim 1, wherein the titer of the warp yarn A is in the range of from 2000 dtex to 5000 dtex.

19. The chain link according to claim 18, wherein the titer of the warp yarn A is in the range in the range of from 2000 dtex to 3000 dtex.

20. The chain link of claim 1, wherein the titer of the warp yarn B is in the range of from 700 dtex to 7500 dtex.

21. The chain link of claim 20, wherein the titer of the warp yarn B is in the range between 800 dtex and 3000 dtex.

22. The chain link of claim 1, wherein the strip in the chain link has a substantially elliptic cross-section.

23. A chain comprising a plurality of chain links, wherein at least one of the chain links is the chain link according to claim 1.

24. A chain comprising at least two interconnected chain links, wherein each of the interconnected chain links is the chain link according to claim 1.

25. A method for enhancing the strength of a chain which comprises: (a) providing the chain according to claim 24, and (b) pre-stretching the chain before use at a temperature below a melting temperature of the yarns.

26. A strip comprising: a longitudinal core section, and longitudinal edge sections, wherein the core section has a thickness which is greater than a thickness of the edge sections, wherein the strip comprises warp yarns containing warp yarn A and warp yarn B, wherein the warp yarn A has a titer which is greater than a titer of the warp yarn B, and wherein the warp yarn A is present in the core section at a concentration which is greater than a concentration of the warp yarn A in the edge sections of the strip, and wherein the warp yarn B is present in the edge sections at a concentration which is greater than a concentration of the warp yarn B in the core section of the strip.

27. A method of manufacturing a chain link comprising winding and fusing the strip of claim 26.

Description

EXAMPLES

(1) Materials and Methods

(2) Intrinsic Viscosity (IV) is determined according to ASTM-D1601/2004 at 135 C. in decalin, the dissolution time being 16 hours, with DBPC as anti-oxidant in an amount of 2 g/l solution, by extrapolating the viscosity as measured at different concentrations to zero concentration. There are several empirical relations between IV and Mw, but such relation is highly dependent on molar mass distribution. Based on the equation M.sub.w=5.37*10.sup.4 [IV].sup.1.37 (see EP 0504954A1) an IV of 4.5 dl/g would be equivalent to a M.sub.w of about 422 kg/mol. Titer of yarn or filament was measured by weighing 100 meters of yarn or filament, respectively. The dtex of the yarn or filament was calculated by dividing the weight (expressed in milligrams) to 10. Alternatively, 10 meters is weighed and dtex is the number of milligram of the yarn length. tex=g/km; dtex=grams/10 km or mg/10 m. The higher the number of dtex, the thicker the yarn. Side chains in UHMWPE sample is determined by FTIR on a 2 mm thick compression molded film by quantifying the absorption at 1375 cm.sup.1 using a calibration curve based on NMR measurements (as in e.g. EP 0 269 151). Tensile properties: tensile strength (or strength) and tensile modulus (or modulus) are defined and determined on multifilament yarns as specified in ASTM D885M, using a nominal gauge length of the fibre of 500 mm, a crosshead speed of 50%/min and Instron 2714 clamps, of type Fibre Grip D5618C. On the basis of the measured stress-strain curve, the modulus is determined as the gradient between 0.3 and 1% strain. For calculation of the modulus and strength, the tensile forces measured are divided by the titer, as determined by weighing 10 metres of fibre; values in GPa are calculated assuming a density of 0.97 g/cm.sup.3. Tenacity (cN/dtex or N/tex; 10 cN/dtex=1 N/tex) of a chain is determined by dividing the breaking strength of the chain by the weight of a unit length of the chain. Weight was corrected by reducing it by the weight of the non-load bearing weft yarns. Breaking strength and elongation at break of a chain are determined on dry chain samples using a Zwick 1484 Universal test machine at a temperature of approximately 21 degree C., and at a strain rate of 0.1/min. Efficiency (%) of a chain is the original tenacity of the chain divided by the tenacity of the load bearing warp yarns (i.e. the tenacity of the ingredient fibers Dyneema SK75 and SK78 was 35 cN/dtex). In case Dyneema DM20 was used, than a weighted tenacity was used, which was 32 cN/dtex resulted from the number of warp yarns (pitches) per fiber grade used in warp direction. The dead weight and the tenacity of the non-load bearing weft yarns were ignored. The maximum breaking load (MBL) is the force necessary to completely rupture a dry sample of a chain, comprising at least three, preferably five chain links. Tensile testing (to measure MBL) of the chain was performed on dry chain samples, comprising at least three, preferably five chain links, using a break load tester 1000 kN Horizontal bench fa. ASTEA (Sittard, The Netherlands) testing machine, at a temperature of about 16 C., a speed of 20 mm/min. Maximum clamp length was 1.2 m and the pin diameter was 150 mm. The chains were tested using D-shackles, the ratio between the diameter of the shackle and the thickness of the tested article connected to them was 5. The D-shackles were arranged in a parallel configuration for the rope. Minimum creep rate of the yarns was determined as indicated in the present patent application and in the published patent application WO2016/001158. The minimum creep rate of the warp yarns have been derived herein from a creep measurement applied on multifilament yarns by applying ASTM D885M standard method under a constant load of 900 MPa, at a temperature of 30 C. and then measuring the creep response (i.e. strain elongation, %) as a function of time. The minimum creep rate is herein determined by the first derivative of creep as function of time, at which this first derivative has the lowest value (e.g. the creep rate [1/s] of the yarn is plotted as function of strain elongation [%] of the yarn in a so-called known Sherby and Down diagram.

Comparative Experiment 1 (CE1)

(3) An 8 layer chain link was wound from a narrow weave strip made of Dyneema SK75 yarns in warp direction, having a strip width of 25 mm, a thickness of 1.5 mm and a length of 400 mm. The strip was commercially available from Gth & Wolf GmbH (silver grey 1 weave) with a nominal breaking strength of 5 tons (49 kN) and a leg weight of 44 g/m. The warp yarns in the strip were made of 120 Dyneema SK75 yarns each having a titer of 1760 dtex, a twist rate of 25 turns per meter (Z25) and 35 cN/dtex initial specific yarn strength and a minimum creep rate of 2.410.sup.5% per second measured at a tension of 900 MPa and a temperature of 30 C.

(4) The yarns in weft direction were made of Dyneema SK60 yarns having a titer of 880 dtex with a twist of 40 turns per meter (Z40) and having a minimum creep rate of 5.810.sup.5% per second measured at a tension of 900 MPa and a temperature of 30 C. and a twist rate of 40 turns per meter (Z40). The ratio of the total weight of the weft yarns to the total weight of the warp yarns was 20:80. The strip (or webbing) was then heat set and pre-stretched at about 120 C. for 2 min and 10% maximum break load (equal to 4.9 kN) and then dip coated in a water dispersed silver colored resin (commercially available from CHT Beitlich GmbH (D), trade name TUBICOAT FIX ICB CONC.) and subsequently dried by hot air stream. The final strip had MBL of 49 kN or 5 metric tons.

(5) A length of the strip was tightly convoluted in 8 layers to form a 0-shape link (loop) of 100 mm inner length bearing a 180 degree twist in each convolution of the strip. A total of 8 convolutions were performed with approximately 2.5 m of the strip. The so formed 180 degree twisted link had approximate circumferences of 100 mm (inner) and 134 mm (outer) and the thickness of the 8 layers links was 12 mm. The 2 ends of the sling overlapped by approximately 110 mm and were stitched together through the thickness of the 180 degrees twisted link over a length of 110 mm with an MW stitching pattern (zig-zag) with XtremeTech 20/40 (Amann & Co GmbH, Germany) sewing threat, made from Dyneema SK75 with a titer of 440 dtex.

(6) A chain was then made by interconnecting five chain links, obtained as described herein above. The total length of this five link chain was 0.6 meter corresponding to a titer of 25660 tex.

(7) Heat-Setting Step

(8) The obtained chain was then pre-stretched five times up to 50% MBL, corresponding to 100 kN for 1 min, at a temperature of 120 C.

(9) Four chain samples, each of them consisting of five chain links were produced as described herein (CE1, CE2, Ex. 1-2). The chains were produced without applying the heat-setting step (sample denoted with a in Table 1) and with applying the heat-setting step (sample denoted with b in Table 1).

(10) The results are presented in Table 1.

Comparative Experiment 2 (CE2)

(11) Comparative Experiment 2 was performed by repeating Comparative Experiment 1, but with the difference that the warp yarn was made of 120 Dyneema DM20 yarns each having a titer of 1760 dtex, a twist of 25 turns per meter (Z25) and a 32 cN/dtex initial specific yarn strength and a minimum creep rate of 1.310.sup.6% per second measured at a tension of 900 MPa and a temperature of 30 C.

(12) The results are presented in Table 1.

Example 1 (Ex.1)

(13) Example 1 was performed by repeating Comparative Experiment 1, but with the following differences:

(14) The warp yarns in the strip were made of yarns having different titers and similar minimum creep rate values, namely [C1]+[B1]+[A]+[B2]+[C2]=[15 Dyneema SK60 yarns having a titer of 880 dtex and Z40 (yarn C1, located in one longitudinal edge section) and a minimum creep rate of 5.810.sup.5% per second measured at a tension of 900 MPa and a temperature of 30 C.]+[20 Dyneema SK78 yarns having a titer of 1760 dtex and Z25 and a minimum creep rate of 1.310.sup.5% per second measured at a tension of 900 MPa and a temperature of 30 C. (yarn B1, located in the same longitudinal edge section together with yarn C1)]+[30 Dyneema SK78 yarns having a titer of 2640 dtex and Z25 and a minimum creep rate of 1.310.sup.5% per second measured at a tension of 900 MPa and a temperature of 30 C. (yarn A, located in the core section)]+[20 Dyneema SK78 yarns having a titre of 1760 dtex and Z25 and a minimum creep rate of 1.310.sup.5% per second measured at a tension of 900 MPa and a temperature of 30 C. (yarn B2, located in the opposite longitudinal edge section)]+[15 Dyneema SK60 yarns having a titer of 880 dtex and Z40 and a minimum creep rate of 5.810.sup.5% per second measured at a tension of 900 MPa and a temperature of 30 C. (yarn C2, located in the opposite longitudinal edge section together with yarn B2)]. (B=B1+B2; C=C1+C2)

(15) Thus, the total of warp yarns [C]+[B]+[A]=[30 Dyneema SK60 yarns having a titer of 880 dtex and Z40 and a minimum creep rate of 5.810.sup.5% per second measured at a tension of 900 MPa and a temperature of 30 C. (yarn C)]+[40 Dyneema SK78 yarns having a titer of 1760 dtex and Z25 and a minimum creep rate of 1.310.sup.5% per second measured at a tension of 900 MPa and a temperature of 30 C. (yarn B)]+[30 Dyneema SK78 yarns having a titer of 2640 dtex and Z25 and a minimum creep rate of 1.310.sup.5% per second measured at a tension of 900 MPa and a temperature of 30 C. (yarn A)], resulting in an amount of warp yarns per titer (i.e. amount of warp yarns or pitches per titer in the warp system) of 15 wt % yarn C, 40 wt % yarn B and 45 wt % yarn A.

(16) The results are presented in Table 1.

Example 2 (Ex. 2)

(17) Example 2 was performed by repeating Example 1, but with the following differences:

(18) The warp yarns comprise Dyneema SK99 yarns having a 42.5 cN/dtex initial specific yarn strength and a minimum creep rate of 710.sup.6% per second measured at a tension of 900 MPa and a temperature of 30 C. and Dyneema DM20 yarns having a 32 cN/dtex initial specific yarn strength and a minimum creep rate of 1.310.sup.6% per second measured at a tension of 900 MPa and a temperature of 30 C.

(19) The warp yarns in the strip were made of yarns having different titers and different minimum creep rate values, comprising [C1]+[B1]+[A]+[B1]+[C2]=[20 Dyneema SK99 yarns having a titer of 880 dtex and Z25 and a minimum creep rate of 710.sup.6% per second measured at a tension of 900 MPa and a temperature of 30 C. (yarn C1, located in one outmost longitudinal edge section)]+[30 Dyneema DM20 yarns having a titer of 1760 dtex and a minimum creep rate of 1.310.sup.6% per second measured at a tension of 900 MPa and a temperature of 30 C. (yarn B1, located in one longitudinal edge section together with yarn C1)]+[20 Dyneema DM20 yarns having a titer of 21760 dtex, thus about 3520 dtex and Z25 and a minimum creep rate of 1.310.sup.6% per second measured at a tension of 900 MPa and a temperature of 30 C. (yarn A, located in the core section)]+[30 Dyneema DM20 yarns having a titer of 1760 dtex and Z25 and a minimum creep rate of 1.310.sup.6% per second measured at a tension of 900 MPa and a temperature of 30 C. (yarn B2, located in the opposite longitudinal edge section)]+[20 Dyneema SK99 yarns having a titer of 880 dtex and Z25 and a minimum creep rate of 710.sup.6% per second measured at a tension of 900 MPa and a temperature of 30 C. (yarn C2, located in one outmost longitudinal edge section together with yarn B2)]. (C1+C2=C; B1+B2=B)

(20) The concentrations with regard to the number of warp yarns (pitches) per titre was [C]:[B]:[A]=16.6%:33%:50% and with regard to weight % of the warp yarns in the warp system: [C]:[B]:[A]=16.6 wt %:33 wt %:50 wt %.

(21) In Examples 1-2, the strip construction has a M/E ratio of about 1, wherein M is the core section in width of the strip and E is the total of the two longitudinal edge sections in the width of the strip, with the total width of the strip consisting of M and E, with M equals E and E=about E1+about E2, with E1 being one longitudinal edge section in width and E2 being the other (or the opposite) longitudinal edge section in width.

(22) The results are presented in Table 1.

(23) The results shown in Table 1 demonstrate that the chains according to the present inventions (chains of Examples 1) have an increase of the breaking strength and efficiency compared to the chains obtained in CE1 and CE2. Namely, an improved chain efficiency was achieved by chain links wound from an elliptic strip profile (chain link comprising a strip made of warp yarns having different titers, Example 1). Before applying a heat setting step, the chain of Example 1a achieved more than 13% efficiency and after heat setting, said chain achieved 31% efficiency (Example 1 b). By applying thus the elliptical strip profile, an optimum saddle profile between chain adjacent links minimized loss in chain efficiency. In addition, it was observed a significant increase of the tenacity value and respectively about 50% reduction of efficiency loss for the chains that were heat set compared to the chains that were not heat set. In addition, a significant reduction of the efficiency losses in the chain interface was achieved in case the strip was hybridized (i.e. either by different creeping warp yarns and/or by different titers in the warp yarns forming an elliptical strip cross-section).

(24) TABLE-US-00001 TABLE 1 Loss in chain Th. Ten. vs. Strip yarn Strip Strip Strip Chain Chain Chain strip Chain Cross- Ten. wt. MBL Ten. wt. MBL Ten. Ten. Eff. Sample Section cN/dtex g/m kN cN/dtex g/m kN cN/dtex cN/dtex % CE1a R 35 25.66 50717 19.7 666.5 22.6 3.73 15.97 10.6 CE1 b R 35 25.66 50717 19.7 666.5 27.8 7.06 12.64 20.2 CE2a R 32 26.13 43163 16.5 654.6 21.7 3.39 13.11 10.4 CE2b R 32 26.13 43163 16.5 654.6 29.1 8.12 8.38 25.4 Ex. 1a E 33.8 22.35 29518 13.2 583.9 16.6 4.64 8.56 13.7 Ex. 1b E 33.8 22.35 29518 13.2 583.9 29.5 10.47 2.73 31 Ex. 2a E Ex. 2b E a = chain sample which was not heat-set; b = chain sample which was heat-set; ; R = Rectangular; E = Elliptic; wt. = weight; Th. = Theoretical; Eff. = Efficiency; Ten. = Tenacity