POLYMERIC CHAIN LINK

Abstract

The present invention relates to a chain link comprising a strip comprising a warp yarn, wherein the strip comprises a longitudinal core section and at least two longitudinal edge sections, and wherein the length of the warp yarn in the edge sections is higher than the length of the warp yarn in the core section of the strip. The invention also relates to a chain comprising said chain link and to use of said chain in different applications.

Claims

1. A chain link comprising a strip comprising weft yarns and warp yarns, wherein the strip comprises a longitudinal core section and longitudinal edge sections, and wherein the length of the warp yarns in the edge sections is higher than the length of the warp yarns in the core section of the strip.

2. The chain link according to claim 1, wherein the length of the warp yarns in the edge sections is at least 2% higher than the length of the warp yarns in the core section of the strip.

3. The chain link according to claim 1, wherein the core section surface of the strip is at least 2% and at most 50% of the total surface of the strip.

4. The chain link according to claim 1, wherein the warp yarns comprises a high performance yarn.

5. The chain link according to claim 4, wherein the high performance yarn comprises a polymer, preferably a polyolefin, more preferably a polyethylene and most preferably UHMWPE.

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

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

8. The chain link according to claim 1, wherein the warp yarns have different titers.

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

10. A chain comprising the chain link according to claim 1.

11. A method for enhancing the strength of the chain according to claim 10, by pre-stretching the chain before use at a temperature below the melting temperature of the material in the yarns.

12. Use of the chain according to claim 10 for storing, securing, such as securing a roll on/off dumpster to a dumpster hauling truck or freight to commercial trucks, flat bed trailers, lashing and tie down for handling and transporting cargo, in lifting and hoisting, logging, hauling and rigging, propulsion and driving, mooring, cargo-hold of an aircraft or naval ship and the like.

13. A strip comprising a longitudinal core section and at least two longitudinal edge sections, wherein the strip comprises weft yarns and warp yarns, with the length of the warp yarn in the edge sections being higher than the length of the warp yarn in the core section of the strip.

Description

EXAMPLES

Materials and Methods

[0075] Intrinsic Viscosity (IV) is determined according to ASTM-D160112004 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.

[0076] 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.

[0077] 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).

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] Minimum creep rate of the yarns was determined as indicated in the present patent application and in the published patent application WO2016001158. 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)

[0085] 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 124 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. All 124 warp yarns were controlled to equal tension and equal feeding speed.

[0086] The yarns in weft direction were made of Dyneema SK60 yarns having a titer of 880 dtex, a twist of 40 turns per meter (Z40) 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.

[0087] 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 (zic-zac) with XtremeTech 20/40 (Amann & Co GmbH, Germany) sewing threat, made from Dyneema SK75 dtex440.

[0088] 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.

[0089] 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.

[0090] Chain samples consisting of five chain links were produced as described herein.

Example 1 (Ex. 1)

[0091] Example 1 was performed by repeating Comparative Experiment 1, but with the difference that via an artificial obstacle (gradual undulation device), higher lengths into outer edge warp yarns were artificially introduced, the more length the more distance from the center (core) of the webbing towards the edges. The outmost edges were at least 10% longer than the warp yarns in the center core of the strip.