The invention relates to a roundsling. Roundslings are used as flexible links between a lifting, or other handling device, and goods that are to be loaded or unloaded. A roundsling is an endless, flexible construction. A roundsling is an endless, flexible sling or loop that generally consists of a load bearing core containing at least two turns of a load-bearing strand material and typically a fully enclosing, protective cover around said core. The roundsling of the invention specifically relates to roundsling with a load bearing core comprising n consecutive parallel loops of at least one load bearing strand comprising at least one multifilament yarn with a tenacity of at least 15 cN/dtex with substantially parallel aligned filaments, wherein the at least one load bearing strand forms at least 4 (n > 4) consecutive parallel loops. The invention further relates to the use of the roundsling according to the invention to lash cargo in road, rail, water and/or air transportation, in conveying, hoisting, suspending, lashing, securing or lifting applications or holding together heavy objects . Roundslings according the invention may be used as multiple interconnected components in a chain, comprising at least two roundslings. The invention further relates to a chain comprising at least one roundslings according to the invention. The invention further relates to a chain comprising at least two interconnected roundslings according to the invention. The invention also relates to the use of the chain according to the invention to lash cargo in road, rail, water and/or air transportation, in conveying, hoisting, suspending, lashing, securing or lifting applications or holding together heavy objects.

Such a roundsling is for example known from US 4,210,089 and US 4,850,629. These patent publications disclose roundslings comprising a load bearing core in the form of parallel turns (also called loops) of load bearing strand material contained within tubular cover means. These roundslings are constructed by forming an endless loop of at least one strand of load bearing material to form a load bearing core, e.g. by placing a plurality of turns of said strand in parallel relationship on a surface having guide means mounted on said surface, fastening said turns at their terminal ends to holding means, pulling a tubular cover means having two ends over one of said guide means to envelop said turns, fastening the terminal ends of said parallel load-bearing turns of the strand and fastening the terminal ends of said cover means to form an endless loop. In these publications the terminal end of the load bearing strand material would ordinarily be fastened to the other end of a strand of the same material, thus forming an end connection and the entire inner core of load- bearing material would be hidden inside the cover material. Typically, fastening of ends is done by making an end-to-end connection, or by connecting the ends to adjacent turns of the strand. End-to-end may also be referred to herein as end-for end. Such connections are for example made by knotting or taping. In case of roundslings that contain a fabric webbing as load-bearing core, the connection can also be made by stitching; as in for example US 4,022,507.

EP0487805 A1 discloses a rope made from composite material.

JP5154920 A discloses a connecting method of an FRP wiry body.

EP031 1199 A1 discloses a Cordage.

A disadvantage of the known roundslings comprising high-tenacity multifilament yarns is that the efficiency of such slings compared to the tenacity of the employed multifilament yarns is low. The efficiency of a roundsling here and hereafter is the ratio of the strength of the load bearing core to the theoretical strength of said load bearing core based on the tenacity of the multifilament yarns composing said core. Efficiency is determined by dividing the tenacity of the roundsling by the tenacity of the load bearing core. The efficiency of known roundslings comprising a core of HMPE multifilament yarns typically ranges between 20% and 40%.

Furthermore EP 1 587 752 describes roundslings constructed from a braided rope as the load-bearing core of which the terminal ends are spliced. Also in US 4,493,599 buoyant rope assemblies are disclosed that contain a spliced rope. The assemblies described, however, concern a‘grommet’ or a hawser but not a roundsling. A‘grommet’ is a single rope loop formed by joining two lengths of ropes by end-to-end splices in each leg; a hawser is a single rope with an eye at each end. Also, such constructions from braided ropes comprising HMPE multifilament yarns have unsatisfactory efficiencies.

It is the aim of the present invention to provide a roundsling with a higher efficiency than the known slings.

This object is achieved according to the invention by providing a roundsling wherein the two ends of said load bearing strand with substantially parallel aligned filaments, having a strength Ts, are connected to each other by at least one connecting means, forming an end connection between said two ends, wherein said end connection has a strength TE such that TE/T _S is at least 0.40.

Brief description of the drawings

Figure 1 schematically depicts an embodiment of the roundsling (1 ) according to the invention. Figures 2A to 2D schematically depict steps of an embodiment of a method according to the invention, said method comprising connecting the two ends of a load bearing strand (2) to each other by a connecting means, forming an end connection (5). 2A occurs before 2B, 2B occurs before 2C and 2D schematically depicts a resulting splice.

Figure 3 schematically depicts an embodiment of a chain (10) according to the invention.

A roundsling according to the invention shows an unexpectedly increased efficiency in that the roundsling retains more from the tenacity of the comprised multifilament yarn, especially for roundslings with high maximum break load. It was further identified that roundslings according to the invention especially have high efficiencies at low number of loops n, increasing the robustness of roundslings with low number of loops.

With the roundsling according to the invention the efficiency may be further increased, where in some cases, the strength of the roundsling is improved by up to 60% as compared to roundslings with load bearing cores comprising the same amount of the multifilament yarns. The roundsling according to the invention therefore can be made lighter than the known roundslings having the same loading capacity. An extra advantage is the lower volume that can thus be obtained.

A roundsling according to European requirements typically comprises 11 turns for one end connection as described in e.g. the standard for polypropylene, polyamide and polyester roundslings EN-1492-2. This number of turns is required because the end connection in the known roundslings generally is unreliable, thus causing a high variation of the tenacity for slings with less than 11 turns. For slings made of HMPE multifilament yarns improvements have been observed while increasing the number of turns to 20 or even 30. Nevertheless, with increasing number of turns, the efficiency of the roundsling reduces. It is postulated that the reduced efficiency is related to inhomogeneity of length, and hence load, between the turns of the load bearing strand. An advantage of the roundsling of the present invention is that the efficiency of the multifilament yarn roundsling is increased even when the number of turns is low. An additional advantage of the roundsling according to the invention is that better efficiency can be obtained when the number of turns is for example 30 or less. Therefor a preferred embodiment of the invention concerns roundslings comprising from 4 to 50 consecutive parallel loops of the load bearing strand, preferably from 5 to 40 and more preferably from 6 to 30.

The roundsling according to the invention comprises at least one load bearing core comprising at least on load bearing strand, the strand preferably is assembled from at least 1 , preferably at least 2, more preferably at least 3 and most preferably at least 4 yarn bundles. The yarn bundles comprise at least one preferably at least 2, and most preferably 4 multifilament yarns. Therefor the term strand in the context of the present application can also be referred to as assembled yarn strand, assembled strand or assembled yarn. A typical load bearing strand present in the load bearing core of the roundsling of the invention comprises e.g. 4 bundles, each bundle comprising 24 yarns, whereby the titer may have a titer of 1 ,760 dtex. Alternatively the titer may have a titer of 2640 dtex or higher. Accordingly such typical load bearing strand may have a titer of about 170,000 dtex. The actual titer of the load bearing strand and load bearing core may vary widely. In a preferred embodiment, the titer of the load bearing strand present in the roundsling according to the invention has a titer of between 2,000 and 2,000,000 dtex, preferably between 4,000 and 1 ,000,000 dtex and most preferably between 10,000 and 500,000 dtex. In a further embodiment of the present invention, the load bearing core may have a titer of between 10,000 and 10,000,000 dtex, preferably between 50,000 and 5,000,000 dtex and most preferably between 100,000 and 2,000,000 dtex. The roundsling of the invention may comprise a load bearing strand and a load bearing core with combined titers as described here above.

The load bearing strand present in the roundsling comprises

multifilament yarns whereby the filaments in each yarn are substantially parallel aligned one to another. Herewith is understood that all the filaments of a multifilament yarn are aligned in the same direction, the direction of the yarn. This stands in contrast to a twisted yarn. The twist level of the yarns is therefore less than 2 turn/meter, preferably less than 1 turn/meter even more preferably less than 0.5 turn/meter. A very low twist level as for example generated by the over-head unwinding from a bobbin or a twist or false twist originating from the yarn manufacturing process is herewith not explicitly excluded. Furthermore, the load bearing strand of the invention may comprise further yarns which are assembled to form said load bearing strand. In the context of the present invention, also the filaments of the different yarns are substantially in parallel alignment to each other, irrespective of the multifilament yarn they belong or belonged to. The assembling of several multifilament yarns into a bundle is also performed without introducing a substantial twist of the yarns or of the bundle, therefor substantially all filaments present in the load bearing strand are in parallel alignment to each other, irrespective of the multifilament yarn they belong or belonged. Such substantially parallel arrangement of all filaments, yarns of a bundle or load bearing strand and a load bearing core are well known in the field result in highest strength efficiency of the load bearing strand and load bearing core, combined with a low elasticity of the concerned strand and core.

The multifilament yarns present in the load bearing strand have a tenacity of at least 15 cN/dtex. Such yarns may also be referred to as high- performance yarns or high-modulus yarns, which comprise high-performance fibers, or high-tenacity fibers, whereby fiber and filament are used interchangeably in the context of the present invention. By fiber or filament is herein understood an elongate body, the length dimension of which is much greater that the transverse dimensions of width and thickness. Accordingly, the term fiber includes filament, ribbon, strip, band, tape, and the like having regular or irregular cross-sections. In the context of the present invention, fibers or filaments have continuous lengths, which stands in contrast to discontinuous lengths, known in the art as staple fibers. A multifilament yarn, also herein called yarn, for the purpose of the invention is an elongated body containing at least 2 filaments, preferably at least 10 filaments.

In the context of the present invention, the strength of the load bearing strand is referred to as Ts and is expressed in N, or kN. The strength of load bearing strands can be calculated by adding the tenacities of all the yarns present in the strand respectively multiplied with the titer of these yarns. For example a strand assembled from 24 yarns, each yarn having a titer of 1760 dtex and a tenacity of 35.1 cN/dtex will have an strength Ts of 14.8 kN.

Such yarns may be manufactured from a polymer chosen from the group consisting of polyamide and polyaramides, e.g. poly(p-phenylene

terephthalamide) (known as Kevlar®); poly(tetrafluoroethylene) (PTFE); poly{2,6- diimidazo-[4,5b-4’,5’e]pyridinylene-1 ,4(2,5-dihydroxy)phenylene} (known as M5);

poly(p-phenylene-2, 6-benzobisoxazole) (PBO) (known as Zylon®); liquid crystal polymers (LCP); poly(hexamethyleneadipamide) (known as nylon 6,6), poly(4- aminobutyric acid) (known as nylon 6); polyesters, e.g. poly(ethylene terephthalate), poly(butylene terephthalate), and poly(1 ,4 cyclohexylidene dimethylene terephthalate); polyvinyl alcohols; and also polyolefins e.g. homopolymers and copolymers of polyethylene and/or polypropylene. The preferred high-performance yarns are polyaramide yarns and high or ultra-high molecular weight polyethylene (HMWPE or UHMWPE) yams. Preferably HMWPE yarns are melt spun and the UHMWPE are gel spun, e.g. yarns manufactured by DSM Dyneema, NL.

In a preferred embodiment of the present invention, the multifilament yarn present in the load bearing strand comprises filaments comprising a polymer chosen from the group consisting of polyaramides, polytetrafluoroethylene, poly{2,6- diimidazo-[4,5b-4’,5’e]pyridinylene-1 ,4(2,5-dihydroxy)phenylene}, poly(p-phenylene-2, 6-benzobisoxazole), liquid crystal polymers (LCP), high or ultra-high molecular weight polyethylene and polypropylene, or combinations thereof, preferably the multifilament yarn comprises polyaramide filaments or ultra-high molecular weight polyethylene (UHMWPE) fibers, or combinations thereof. Such yarns show the best strength to weight ration and provide roundslings which are both strong and light.

In a preferred embodiment, the high-performance yarns are UHMWPE yarns, more preferably gel spun UHMWPE fibers. Preferably the UHMWPE present in the UHMWPE yarn has an intrinsic viscosity (IV) of at least 3 dl/g, more preferably at least 4 dl/g, most preferably at least 5 dl/g. Preferably said IV is at most 40 dl/g, more preferably at most 30 dl/g, more preferably at most 25 dl/g. The IV may be determined according to ASTM D1601 (2004) at 135°C in decalin, the dissolution time being 16 hours, with BHT (Butylated Hydroxy Toluene) as anti-oxidant in an amount of 2 g/l solution, by extrapolating the viscosity as measured at different concentrations to zero concentration. Examples of gel spinning processes for the manufacturing of UHMWPE fibers are described in numerous publications, including WO 01/73173 A1 , EP

1 ,699,954 and in“Advanced Fibre Spinning Technology”, Ed. T. Nakajima, Woodhead Publ. Ltd (1994), ISBN 185573 182 7.

The high-performance yarns may have a high tenacity and/or a high strength. In the context of the present invention high-performance yarns are

understood to be yarns with a tenacity of at least 15 cN/dtex, preferably the

multifilament yarn has a tenacity of at least 18 cN/dtex, preferably at least 20 cN/dtex, more preferably at least 22 cN/dtex, even more preferably at least 25 cN/dtex and most preferably at least 30 cN/dtex. When the high-performance yarns are UHMWPE yarns, said UHMWPE yarns preferably have a tenacity of at least 18 cN/dtex, more preferably of at least 25 cN/dtex, most preferably at least 35 cN/dtex. Preferably the high- performance yarn has a modulus of at least 300 cN/dtex, more preferably of at least 500 cN/dtex, most preferably of at least 600 cN/dtex. Preferably the UHMWPE yarn has a tensile modulus of at least 500 cN/dtex, more preferably of at least 800 cN/dtex, most preferably of at least 1000 cN/dtex. In the context of the present invention tenacity, tensile strength and tensile modulus are defined and determined on multifilament yams 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”. The modulus is determined as the gradient between 0.3 and 1 % strain. In case the titer of the multifilament yarn present in the load bearing strand cannot be identified, tenacity, tensile strength and tensile modulus of the multifilament yarn is determined on yarns with a linear weight (titer) of between about 1000 and 2000 dtex.

Load bearing cores comprising the high-performance yarns may provide roundslings with high strength. Therefor an embodiment of the present invention concerns roundslings wherein the sling has a tenacity of at least 5.0 cN/dtex, preferably the roundsling has a tenacity of at least 6.0 cN/dtex, more preferably of at least 7.0 cN/dtex, even more preferably 8.0 cN/dtex and most preferably at least 10.0 cN/dtex. Herein the tenacity of a roundsling is understood to be the load at break of the roundsling (in cN) divided by the titer (in dtex) of the sum of the two legs of the roundsling.

A roundsling according to the invention shows an unexpectedly increased efficiency in that the roundsling retains more of the tenacity of the comprised multifilament yarns, especially for high break load (BL) roundslings.

Preferably, the static strength of the roundsling of the invention is at least 10 kN, more preferably at least 50 kN, even more preferably at least 100 kN, yet even more preferably at least 300 kN, yet even more preferably at least 1000 kN, yet even more preferably at least 10,000 kN, yet even more preferably at least 50,000 kN, and most preferably at least 100,000 kN, By static strength is herein understood the strength of the roundsling when subjected to a static load also referred to as the breaking strength or break load (BL). In an embodiment the break load is measured as described in the experiments herein, where it is referred to as breaking strength. In a yet preferred embodiment, the static strength of the roundsling is between 10 kN and 1 ,000,000 kN, preferably between 50 kN and 500,000 kN, most preferably between 100 kN and 100,000 kN. In another preferred embodiment, the static strength of the roundsling is at least 10 kN, more preferably of at least 50 kN and most preferably of at least 100 kN. The BL may be obtained by testing according to ISO 2307, whereby the tenacity of the roundsling is calculated by dividing said MBL by the combined titer of the 2 legs.

It was found that the mechanical properties of the roundsling according to the invention, in particular its strength can be improved by pre-stretching the roundsling prior to its use below the melting point of the polymer. For UHMWPE yarns the pre-stretching of the roundsling is performed between 80 - 140°C, more preferably between 90 - 130°C.

The load bearing core of the roundsling according to the invention comprises at least 4 consecutive, parallel turns of a load bearing strand, whereas the load bearing core preferably comprises more than 4 consecutive turns of said strand. The load bearing core may also comprise single or multiple turns of further (second, third, etc.) load bearing strands. By turn, loop or wrap, in the context of the present invention is understood that a length of a load bearing strand completes a loop or revolution within the core of the roundsling, said strand being a constituting part of the core or even that the strand, and optional further strands, form the load bearing core. In this context turn may be synonym to loop, wrap or revolution. By consecutive turns is understood that said length of strand after completion of a first turn is directly engaged in a second turn within the load bearing core. Typically the length of each of the consecutive turns are substantially equal to each other. Upon manufacturing, and depending upon the winding process, further layers might show a subtle increase in length due to the increasing circumference of the growing load bearing core.

Nevertheless, such increase might be compensated by adequate winding pattern known to the skilled person and might further be reduced upon use and setting of the load bearing strand. In accordance with the foregoing, the core of the roundsling of the invention have a cross-section comprising a number of cross-sections of load bearing strands originating from the same or different load bearing strands.

In one embodiment of the invention the roundsling comprises a further load bearing core comprising n consecutive parallel loops of at least one further load bearing strand and/or comprises a load bearing core further comprising n consecutive parallel loops of at least one further load bearing strand. Such roundslings with more than one load bearing core or with a load bearing core comprising more than one load bearing strand are relevant design variations allowing production of different quality roundslings based on a limited number of load bearing cores and/or load bearing strands.

The at least one load bearing core of the roundsling according to the invention may comprise one or more further load bearing strands, each further strand forming a single, preferably multiple consecutive turns, preferably at least 5 parallel turns in the load bearing core. Said further load bearing strands allow an increased design flexibility at reduced manufacturing effort. Preferably the number of further strands in the load bearing core is at most 11 , more preferably at most 5, whereas more preferably the total number of load bearing strands, including the first strand, in the load bearing core is 1 , 2, 3, 4 or 6. It was identified that said preferred number of strands represents a good compromise between manufacturing advantages and damage tolerance of the roundsling of the invention.

In a preferred embodiment the load bearing core comprises one or more further load bearing strands wherein said core comprises at least 4 consecutive, parallel turns of each of the one or more further strands, preferably at least 5 consecutive turns, more preferably at least 6 and most preferably at least 8

consecutive turns of each of the one or more further strands. Accordingly in said preferred embodiment a load bearing core of the roundsling of the invention may comprise a total of 2, 3, 4 or 6 distinct load bearing strands, whereby at least 2, preferably all, of said strands form at least 4, preferably at least 5 turns, more preferably at least 6 and most preferably at least 8 consecutive turns of the load bearing core.

Adding the number of turns of each of the distinct load bearing strands will provide the total number of turns of strands present in the load bearing core. In a preferred embodiment the ratio of the total number of strand turns in the load bearing core to the number of strands in the load bearing core is at least 4, preferably at least 5, more preferably at least 6 and most preferably at least 8. It was identified that the higher said ratio the more damage tolerant the roundsling according to invention is.

As discussed above, the multifilament yarn present in the load bearing strands and the load bearing core may be selected from a variety of high-tenacity yarns. In one embodiment of the invention all yarns acting as load bearing component in the load bearing strand or strands are the same multifilament yarn. In another embodiment of the invention, a further, different, yarn is present in the load bearing strand, load bearing strands and/or load bearing cores. Therefor a preferred embodiment of the invention concerns a roundsling wherein the load bearing core or the load bearing strand comprises at least one further multifilament yarn, different from the first multifilament yarn, preferably the at least one further multifilament yarn comprises filaments comprising a polymer chosen from the group consisting of polyaramides, polytetrafluoroethylene, poly{2,6-diimidazo-[4,5b-4’,5’e]pyridinylene- 1 ,4(2,5-dihydroxy)phenylene}, poly(p-phenylene-2, 6-benzobisoxazole), liquid crystal polymers (LCP), high or ultra-high molecular weight polyethylene and polypropylene.

In a yet preferred embodiment the first load bearing strand comprises a first multifilament yarn and the one or more further load bearing strand comprise one or more further multifilament yarns, whereby the polymers of the first and the one or more further elongated elements are of the same type, preferably the first strand and the one or more further strands comprise polymeric fibers of the same type, even more preferably the first primary strand and the one or more further primary strands comprise polymeric yarns of the same type.

In an alternative preferred embodiment the first strand comprises a first multifilament yarn and the one or more further strands comprise one or more further multifilament yarns, wherein at least one of the one or more further multifilament yarns differ from the first multifilament yarn, preferably the at least one of the one or more further multifilament yarns differ from the first multifilament yarn by at least one property selected from the list consisting of material, tenacity, yarn titer, filament titer or creep rate.

Even better results are obtained when the multifilament yarns present in the roundsling according to the invention are coated. The coating may reduce the coefficient of friction between the filaments and the yarns and may hence allow longitudinal movement of the filaments and/or the yarns to each other and compensate for potential length differences between the filaments and/or yarns that may stem from the production process or handling of the roundsling. Preferably the coating is a lubricity improving coating. Such coatings are well known in the art such as PTFE, silicon oil or crosslinked silicone resin. Therefor a further embodiment of the present invention concerns a roundsling wherein the multifilament yarn comprises a coating, preferably a lubricity improving coating.

The roundsling may further comprise a protective covering around the core. This cover, sleeve, or jacket can be any known material, like a woven or braided fabric, e.g. a woven polyester fabric or braided abrasion resistant UHMWPE cover. The cover may be a knitted fabric, e.g. a knitted polyester fabric or braided abrasion resistant UHMWPE cover. Therefor an embodiment of the present invention concerns a roundsling wherein the at least one load bearing core is sheathed in a protective cover.

The two ends of the at least one load bearing strand are attached to each other by a connecting means, forming an end connection between the two ends. Although the looped construction of the sling inherently prevents shifting of the individual turns of the load bearing strand, it was observed that use of adequate connecting means is critical to improve the efficiency of the roundsling. By connecting means is herein understood any device or method to firmly unite the 2 ends of the load bearing strand. Examples of connecting means in the context of the present invention may be splicing, stitching, glue, bolts, shackle, heat sealing, rivets or the like, whereby a critical aspect of said connecting means is that the so formed end connection between the two ends of the load bearing strand has a strength TE of at least 40% of the strength of the load bearing strand (Ts), in other words, the ratio TE/TS is at least 0.40. Preferably the ratio TE/TS is at least 0.45, more preferably at least 0.50 and most preferably at least 0.55.

The strength of the end connection (TE) can be measured by methods known to the person skilled in the art. Preferably T _E is measured on a strand comprising the concerned connecting mean whereby the two free ends of the end- connected load bearing strand are wrapped 5 times around the load applying pin and secured. An alternative way is by producing an endless shaped article, i.e. a loop, comprising a single turn of the concerned load bearing strand and connecting the ends of said strand by the connecting means. The produced loop can now be subjected to a tensile test whereby the loop is positioned in such a way that the end connection is present in the straight, linearly tensioned section of the loop. The measured load at break of the loop corresponds to two times the strength of the end connection.

As preferred type of an end connection embodiment, the connecting means is a splice between the two ends of the load bearing strand. While the load bearing strand comprises substantially parallel arrangement of fibers and yarns, in said preferred end connection required lengths at both ends of the load bearing strand are braided or laid arrangements of the yarns and/or bundles present in the strand. Said braided or laid sections of the load bearing strand are spliced with each other to form the end connection. The braided or laid section at each end of the strand has a length substantially shorter than the length of the substantially parallel arrangement of the load bearing strand and does typically not exceed half of the length of the load bearing core, preferably not exceed one third of the length of the load bearing core. Therefor a preferred embodiment of the present invention concerns a roundsling comprising overlapping lengths of the two ends of the load bearing strand, wherein the two ends of the load bearing strand are both laid or braided and wherein the connecting means is a splice between the two laid or braided ends of the load bearing strand. Various known tucked or buried splices may be applied.

In an embodiment the end connection comprises a splice having a length of less than the length (I) of the sling. The effective work length of a sling is the actual finished length of the sling construction, inclusive fittings, from bearing point to bearing point.

In an aspect of the invention the end connection of the roundsling is a splice consisting of at least one yam bundle, preferably at least two, preferably consisting of at least 4 yarn bundles. In this aspect the splice does not comprise an adhesive, a binding agent or other means, such as a curing resin, to adhere the yarn bundles and the yarns in the yarn bundle together. A benefit of such splice without means to adhere the yarn bundles and the yarns in the yarn bundle together includes that the bundles may slip a bit relative to each other and relax to a situation where the strands have substantially the same length and forces are distributed more evenly across the bundles. This result in a stronger connection and a more efficient roundsling.

In an aspect of the invention the end connection of the roundsling all strands and all yarn bundles, and therefore all multifilament yarns are used in the splice. This increases efficiency.

Splice constructions that may be employed for the present invention will be well known to the skilled person and are amongst others know from for example Chapter 7 of the Handbook of fibre rope technology (eds McKenna, Hearle and O’Hear, Woodhead Publishing Ltd, ISBN 1 85573 606 3) or W016059261. By constructing the splice the skilled person will attempt to strike a balance between the reliability, including the strength, of the splice and the length of the splice. For economical but also manufacturing reasons the splice should be as short as possible but long enough to avoid slippage of the splice. In a preferred embodiment, the roundsling comprises an end connection having a length of between 3 and 15 tucks.

In a preferred embodiment of the invention the two ends of the load bearing strand are of laid construction, preferably said laid construction comprises 3, 4, 6, or 6+1 sub-strands wherein the splice structure is a tucked splice between the two ends of the load bearing strand, the advantage being very little slip in the spliced connection.

In another preferred embodiment of the invention the two ends of the load bearing strand are of braided construction, preferably said braided construction comprises4, 6, 8, or 12 sub-strands. Preferably the splice structure comprises a tucked splice or an insert splice (also called buried splice) between the ends of the load bearing strand.

Good results are obtained when the strand ends are treated with a thermoplastic or thermosetting adhesive polymeric coating material, e.g. a

polyurethane dispersion like Beetafin ^® L9010, a modified polyurethane dispersion like LAGO ^® 45 or 50 or semi-crystalline polyolefin dispersion. The identification of the adequate coating for the multifilament is in the reach of the skilled person. Such thermoplastic or thermosetting coating maybe applied as the main connecting means or as a further connecting means combined for example with a splice or any other connecting means. In such case the thermoplastic or thermosetting coating may be applied before, during or after the other connecting means is applied. In case the thermoplastic or thermosetting coating is used as the main connecting means, the filaments of the multifilament yarns of the two ends of the load bearing strand preferably are intimately mixed with each other while maintaining their substantial parallel alignment. Preferably the filaments are kept taught during the drying and hardening process of the coating. In an aspect the filaments are kept taught during the drying and curing process of the coating. Such coating allows a shorter splice without losing efficiency or causing an increase of the variation of the tenacity. It also allows a shorter production time of the end connection. A further advantage of such roundsling is the robust and stable connection which shows no substantial loosening of the end connection during manipulation. Therefor a preferred embodiment of the present invention concerns a roundsling according wherein the end connection comprises overlapping lengths of the two ends of the load bearing strand and comprising a connecting mean being a thermoplastic or thermosetting resin present between the multifilament yarns of the overlapping ends of the load bearing strand. In a preferred embodiment, the overlapping lengths are from 10 to 100 times the diameter of the equivalent circular cross-section of the load bearing strand. Herein the equivalent circular cross-section is understood to be the cross-section the load bearing strand would have when brought into substantially circular shape. In case the end connection is a splice the overlapping lengths of the two ends of the load bearing strand may be referred to as length of the splice herein.

In an embodiment the diameter of the equivalent circular cross-section of the splice is at least two times the diameter of the equivalent circular cross-section of the load bearing strand. In an embodiment the diameter of the equivalent circular cross- section of the splice is in the range of at least two times to at most ten times the diameter of the equivalent circular cross-section of the load bearing strand.

The present invention further relates to a method for constructing a roundsling according to the invention, comprising the step of winding at least 5 parallel loops of a load bearing strand with a strength Ts on two reels, wherein the load bearing strand comprises at least one multifilament yarn with substantially parallel aligned filaments, the multifilament yarn having a tenacity of at least 15 cN/dtex, forming the load bearing core, wherein part of the loops is on the reels and part is between the reels, the step of connecting the two ends of the load bearing strand to each other by a connecting means, forming an end connection, wherein said end connection between the two ends of the load bearing strand has a strength TE such that TE/T _S is at least 0.4. In a preferred embodiment of the method according to the invention comprises the step of connecting the two ends of the load bearing strand comprises the step of braiding or twisting each of the two ends of the load bearing strand and the step of splicing the braided or twisted ends of the load bearing strand to form an end connection with a tenacity TE such that TE/T _S is at least 0.4.

The invention further relates to the use of the roundsling according to the invention to lash cargo in road, rail, water and/or air transportation, in conveying, hoisting, suspending, lashing, securing or lifting applications or holding together heavy objects.

In an aspect the invention relates to the use of the roundsling according to the invention as master link in a lifting bridle.

In an aspect the invention relates to the use of the roundsling according to the invention as connection link for mooring. For example for mooring a ship or a platform.

In an aspect the invention relates to the use of the roundsling according to the invention in combination with a lifting point. Examples of a lifting point includes a boltable or weldable connector to connect the sling with the object to lift.

In an aspect the invention relates to the use of the roundsling according to the invention in combination with lashing point. Examples of a lashing point includes a boltable or weldable connector to connect the sling with the object to lash.

The invention further relates to a chain comprising at least one roundsling according to the invention. The invention further relates to a chain comprising at least two roundslings according to the invention. In an aspect the chain according to the invention comprises multiple interconnected roundslings according to the invention which are connected to eachother. The roundsling then functions as chain link. A chain should desirably be capable of transmitting forces under all kinds of circumstances and environmental conditions, often for a prolonged period of time, without the chain being affected in any way, such as by breaking, fraying, cut, fatigue, ageing, corrosion, damaging, and so on. Other requirements may also be important. During use in the above-mentioned operations, chains are subjected to substantial wear and tear conditions which may lead to extensive abrasion of the chain. Chains should therefore be durable. Chains moreover should not only be strong and durable, but at the same time be as lightweight as possible, in order not to unduly increase health risks during handling or reduce payload, this requirement being even more important for heavier, stronger chains. The object of the present invention is to provide a chain very well capable of transmitting forces. In general chains are easily tailored according to their needs. For instance, their length is easily adjusted by connecting at the appropriate chain link or adding or removing chain links. Adding links may be carried out by winding at least one load bearing strand through the opening of an existing chain-link, and securing the newly made chain-link by the splice as described herein.

The invention includes the following embodiments

1. A roundsling (1 ) comprising a load bearing core comprising n consecutive

parallel loops of at least one load bearing strand (2) with a strength Ts, wherein the at least one load bearing strand comprises at least one multifilament yarn (4) with a tenacity of at least 15 cN/dtex with substantially parallel aligned filaments, wherein n is at least 4, characterized in that the two ends (I and II) of said load bearing strand are connected to each other by at least one connecting means, forming an end connection (5) between said two ends, wherein said end connection has a strength TE such that TE/T _S is at least 0.40.

2. The roundsling according to embodiment 1 , wherein the strand is assembled from at least 1 yarn bundle, preferably at least 2 yarn bundles.

3. The roundsling according to embodiment 1 , wherein the strand is assembled from at least 3 yarn bundles, preferably at least 4 yarn bundles.

4. The roundsling according to embodiment 2, wherein the yarn bundles comprise at least one, preferably at least 2 multifilament yarns.

5. The roundsling according to embodiment 2, wherein the yarn bundles

comprises least 4 multifilament yarns.

6. The roundsling according to any preceding embodiment, wherein the filaments in the multifilament yarns are substantially parallel aligned one to another.

7. The roundsling according to any preceding embodiment, wherein substantially all filaments present in the load bearing strand are in parallel alignment to each other.

8. The roundsling (1 ) according to embodiment 1 wherein the multifilament yarn comprises filaments (4) comprising a polymer chosen from the group consisting of polyaramides, polytetrafluoroethylene, poly{2,6-diimidazo-[4,5b- 4’,5’e]pyridinylene-1 ,4(2,5-dihydroxy)phenylene}, poly(p-phenylene-2, 6- benzobisoxazole), liquid crystal polymers (LCP), high or ultra-high molecular weight polyethylene and polypropylene, 9. The roundsling according to embodiment 1 , wherein the multifilament yarn comprises polyaramide filaments or ultra high molecular weight polyethylene (UHMWPE) fibers.

10. The roundsling according to any preceding embodiment wherein the

multifilament yarn has a tenacity of at least 18 cN/dtex.

1 1. The roundsling according to any preceding embodiment wherein the

multifilament yarn has a tenacity of at least 20 cN/dtex.

12. The roundsling according to any preceding embodiment wherein the

multifilament yarn has a tenacity of at least 22 cN/dtex.

13. The roundsling according to any preceding embodiment wherein the

multifilament yarn has a tenacity at least 25 cN/dtex.

14. The roundsling according to any preceding embodiment wherein the

multifilament yarn has a tenacity of at least 30 cN/dtex.

15. The roundsling according to any preceding embodiment wherein the

multifilament yarn has a tenacity of at least 40 cN/dtex.

16. The roundsling according to any preceding embodiment characterized in that n is in the range from 4 to 150.

17. The roundsling according to any preceding embodiment characterized in that n is in the range from 4 to 100.

18. The roundsling according to any preceding embodiment characterized in that n is in the range from 4 to 50.

19. The roundsling according to any preceding embodiment characterized in that n is in the range from 5 to 40.

20. The roundsling according to any preceding embodiment characterized in that n is in the range from 6 to 30.

21. The roundsling according to any preceding embodiment wherein the

multifilament yarn comprises a coating.

22. The roundsling according to any preceding embodiment wherein the

multifilament yarn comprises a lubricity improving coating.

23. The roundsling according to any preceding embodiment wherein the load bearing strand has a titer of between 2,000 and 2,000,000 dtex and the load bearing core has a titer of between 10,000 and 10,000,000 dtex.

24. The roundsling according to any preceding embodiment wherein the load bearing strand has a titer of between 4,000 and 1 ,000,000 dtex and the load bearing core has a titer of between 50,000 and 5,000,000 dtex. 25. The roundsling according to any preceding embodiment wherein the load bearing strand has a titer of between 10,000 and 500,000 dtex and the load bearing core has a titer of between 100,000 and 2,000,000 dtex.

26. .The roundsling according to any preceding embodiment, wherein the load bearing core or the load bearing strand comprises at least one further multifilament yarn.

27. The roundsling according to any preceding embodiment, wherein the load

bearing core or the load bearing strand comprises at least one further multifilament yarn wherein the at least one further multifilament yarn comprises filaments comprising a polymer chosen from the group consisting of

polyaramides, polytetrafluoroethylene, poly{2,6-diimidazo-[4,5b- 4’,5’e]pyridinylene-1 ,4(2,5-dihydroxy)phenylene}, poly(p-phenylene-2, 6- benzobisoxazole), liquid crystal polymers (LCP), high or ultra-high molecular weight polyethylene and polypropylene.

28. The roundsling according to any preceding embodiment comprising a further load bearing core comprising n consecutive parallel loops of at least one load bearing strand and/or comprising a load bearing core further comprising n consecutive parallel loops of at least one further load bearing strand.

29. The roundsling according to any preceding embodiment comprising a further load bearing core comprising n consecutive parallel loops of at least one load bearing strand.

30. The roundsling according to any preceding embodiment, wherein the number of load bearing strands, including the first strand, in the load bearing core is 1 , 2,

3, 4 or 6.

31. The roundsling according to any preceding embodiment comprising a further load bearing core comprising a load bearing core further comprising n consecutive parallel loops of at least one further load bearing strand.

32. The roundsling according to any preceding embodiment comprising a further load bearing core comprising n consecutive parallel loops, wherein n is in the range from 4 to 150.

33. The roundsling according to any preceding embodiment comprising a further load bearing core comprising n consecutive parallel loops, wherein n is in the range from 4 to 100.

34. The roundsling according to any preceding embodiment comprising a further load bearing core comprising n consecutive parallel loops, wherein n is in the range from 4 to 50. 35. The roundsling according to any preceding embodiment comprising a further load bearing core comprising n consecutive parallel loops, wherein n is in the range from 5 to 40.

36. The roundsling according to any preceding embodiment comprising a further load bearing core comprising n consecutive parallel loops, wherein n is in the range from 6 to 30.

37. The roundsling according to any preceding embodiment wherein the at least one load bearing core is sheathed in a protective cover.

38. The roundsling according to any preceding embodiment wherein the roundsling has a minimum load at break of between 10 kN and 1.000.000 kN.

39. The roundsling according to any preceding embodiment wherein the roundsling has a minimum load at break of between 50 kN and 500.000 kN.

40. The roundsling according to any preceding embodiment wherein the roundsling has a minimum load at break of between 100 kN and 100.000 kN.

41. The roundsling according to any preceding embodiment wherein the end

connection comprises a splice having a length of less than a loop length (I) of the sling.

42. The roundsling according to any preceding embodiment, wherein the first end (I) and the second end (II) are laid in opposite configuration.

43. The roundsling according to any preceding embodiment, wherein the first end (I) is laid in an S configuration and wherein the second end (II) is laid in a Z configuration.

44. The roundsling according to any preceding embodiment, wherein the first end (I) is laid in a Z configuration and wherein the second end (II) is laid in a S configuration.

45. The roundsling according to any preceding embodiment, wherein the end

connection has a length of between 4 and 60 tucks, and wherein the number of tucks is the total number of tucks in both directions.

46. The roundsling according to any preceding embodiment, wherein the end

connection has a length of between 6 and 30 tucks, and wherein the number of tucks is the total number of tucks in both directions.

47. The roundsling according to any preceding embodiment wherein the end

connection has a length of between 3 and 15 tucks.

48. A method for constructing a roundsling (1 ) according to any one of the

preceding embodiments, comprising

the step of winding at least 5 parallel loops of a load bearing strand (2) with a strength Ts on two reels, wherein the load bearing strand comprises at least one multifilament yam (4) with substantially parallel aligned filaments, the multifilament yam having a tenacity of at least 15 cN/dtex, forming the load bearing core (8), wherein part of the loops is on the reels and part is between the reels,

the step of connecting the two ends of the load bearing strand to each other by a connecting means, forming an end connection (5), wherein said end connection between the two ends of the load bearing strand has a strength T _E such that TE/TS is at least 0.40.

49. The method of the previous embodiment wherein the step of connecting the two ends of the load bearing strand comprises the step of braiding or twisting each of the two ends of the load bearing strands and the step of splicing the braided or twisted ends of the load bearing strand to form an end connection with a tenacity TE such that TE/TS is at least 0.4.

50. A chain (10) comprising at least one round sling (1 ) according to any one of the preceding embodiments.

51. A chain (10) comprising at least two interconnected round slings (1 ) according to any one of the preceding embodiments.

52. A chain (10) comprising at least three interconnected round slings (1 ) according to any one of the preceding embodiments.

53. Use of a sling (1 ) according any preceding embodiment to lash cargo in road, rail, water and/or air transportation, in conveying, hoisting, suspending, lashing, securing or lifting applications or holding together heavy objects.

54. Use of a chain (10) according any preceding to moor or anchor boats or other objects, to lash cargo in road, rail, water and/or air transportation, in conveying, hoisting, suspending, lashing, securing or lifting applications or holding together heavy objects.

55. A method of making a chain (10) comprising the step of

- connecting roundslings (1 ) according to any preceding embodiment.

56. The method of making a chain according to any preceding embodiment,

wherein the connecting includes the steps of

a. winding at least 4 parallel loops of a further load bearing strand through the opening of an existing round sling and around a reel; and b. connecting the two ends as described in the preceding embodiments concering method for constructing a roundsling. Detailed Figure description

Figure 1 schematically depicts an embodiment of the roundsling (1 ) according to the invention. The depicted roundsling (1 ) has four consecutive parallel loops of a load bearing strand (2). The four loops of the load bearing strand (2) form the load bearing core (8) (schematically depicted in Fig 1A). The strands are arranged in a substantially parallel manner. The load bearing strand (2) comprises four yarn bundles (4)

(schematically depicted in Fig 1 B) . The yarn bundles comprises filaments ( not shown), these filaments are arranged in a substantially parallel manner. The two ends of the strand (2) are connected through a splice (5). The roundsling has a loop length ( L). Typically the length of each of the consecutive turns (loops) are substantially equal to each other.

Figures 2A to 2D schematically depict steps of an embodiment of a method according to the invention, said method comprising connecting the two ends of a load bearing strand (2) to each other by a connecting means, forming an end connection (5).

Figures 2A to 2D schematically depict steps to make a splice from ends I and II in the roundsling (1 ) according to the invention. 2A occurs before 2B, 2B occurs before 2C and 2D schematically depicts a resulting splice.

Figure 2A schematically depicts the two ends of a load bearing strand (2) comprising 4 yarn bundles (4). End I (I) is twisted clockwise. End II (II) is twisted counter clockwise. Before twisting a first temporary fixing means (7) such as a tape is placed at each end to ensure only part of the strand (2) is twisted.

Figure 2B schematically depicts the two ends of the load bearing strand (2) where part of the ends (I and II) of the stand are twisted and part of the ends have loose hanging ends (3). End I is twisted in an S-configuration. End II is twisted in a Z-configuration. A second temporary fixing means (9) such as a tape is placed to ensure the twisted parts stay twisted during making of the end connection. The second temporary fixing (9) means is placed over the twisted part such that the length of the twisted part (Lt) between the first temporary fixation means (7) and the second temporary fixation means (9) is long enough for making a splice. This means the twisted part (Lt) of each end is at least half of the splice length (L) (see Figure 2D). Splicing herein is the forming of a joint between the two ends (I and II) of the same load bearing strand (2). Typically splicing includes untwisting of the twisted part between the second temporary fixation means and the bitter end (12) such that loose hanging ends (3) are formed. In a next step of the splicing the loose hanging ends (3) of the yam bundles (4) of one end of the strand (2) are tucked into the twisted part (Lt) of the other end of the strand.

Figure 2C schematically depicts the load bearing strand (2) where the two ends (I and II), each having a twisted part (I and II resp.) are brought together. A third temporary fixing means (11 ) such as a tape is placed to ensure the stay ends in place during making of the end connection.

The loose ends (3) of end I are tucked in the twisted part of end II and vice versa. The result is schematically depicted in Fig 2D. Figure 2D shows a schematic representation of an end connection in the form of a splice (5) having ten tucks (6). The remaining parts of the loose hanging ends (3) have been reduced by cutting them off. The end connection comprises overlapping lengths L2 of the two ends of the load bearing strand. In other words the length of the splice is depicted as L2.

Figure 3 schematically depicts an embodiment of a chain (10) according to the invention. This embodiment of the chain comprises six roundslings (1 ) according to the invention. Each roundsling comprises a splice (5). The roundslings are connected to eachother, i.e. are interconnected. The splice may be located at different positions in the round sling, as is schematically depicted by 5a.

METHODS OF MEASURING

• Intrinsic Viscosity (IV) of UHMWPE is determined according to ASTM-D 1601/2004 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.

• Tensile properties, i.e. strength and modulus, were determined on multifilament yarns as specified in ASTM D885M, using a nominal gauge length of the yarn of 500 mm, a crosshead speed of 50%/min and Instron 2714 clamps, of type Fibre Grip D5618C. For calculation of the strength of the yarn, the tensile forces measured may be divided by the titer, as determined by weighing 10 meter of fibre; values in GPa for are calculated assuming the natural density of the polymer, e.g. for UHMWPE is 0.97 g/cm ³ .

Tenacity of parallel load bearing strands (Ts) is calculated by multiplying the measured yarn tenacity by the number of yarns present in the load bearing strand. For assembled load bearing strands where the individual yarns became undistinguishable, tensile properties are determined on reconstructed multifilament yarns with a titer of about 1 ,000 dtex.

• The end-connection breaking strength (T _E ) was measured on a Zwick tensile tester machine 1484-TE01 whereby the two free ends of the end-connected load bearing strand where wrapped 5 times around the pin and secure. The breaking strength (or load at break) of the end connection is determined on a sample length of about 5.15 m, with a pin diameter of 80 mm and after five times applying a pre-load of about 20% of the load bearing strand at a testing speed of 2000 N/sec.

• Breaking strength of the roundsling of slings with a strength of up to 10,000 kN is determined on dry samples using a horizontal tensile tester with a max load capacity of 15,000 kN at a temperature of approximately 21 °C, and at a rising force velocity of 250kN/min. The roundslings were tested using D-shackles with a diameter of the shackle of 95 mm (< 1 MTex) and 220 mm (> 1 MTex). The D- shackles are arranged in parallel configuration.

Roundsling tenacity was calculated by dividing the breaking strength of the sling by the titer of the 2 legs of the load bearing core. Covers or coatings are disregarded when assessing the titer.

A Breaking strength than of over to 10,000 kN may determined on dry samples using a horizontal tensile tester analogous to described above with a higher maximum load capacity.

• Efficiency is determined by dividing the tenacity of the roundsling by the tenacity of the load bearing core.

EXPERIMENTS EXAMPLE 1

For the determination of the strength (T _E ) of the different types of end connections, a load bearing strand is formed by assembling an adequate number of multifilament yarns. The assembled strand is linked end-to-end by a corresponding end connection e.g. a knot, a spliced braid, a sliced lay, a thermoplastic or thermosetting coating applied to the overlapping ends of the strand. The strength of these end connections are reported in Table 1 whereby the strength of the load bearing strands are reported as theoretical strength based on the tenacity of the yarns present therein. The efficiencies of the end connection is calculated by dividing the strength of the end connection (T _E ) by the strength of the load bearing strand (Ts). It can be observed that for both UHMWPE and aramid yarns, the efficiency of the knotted end connection is substantially lower than the efficiency of the spliced end connection.

Table 1

Yam Break Load Efficiency

Strand T _E

4 ^* 24 ^* 1760 UHMWPE (SK78) 1 18.6 kN

4 ^* 25 ^* 1670 Aramid (T200) 81.8 kN

End-connection TE/TS 4 ^* 24 ^* 1760 Knotted UHMWPE 21.6 kN 0.18

4 ^* 24 ^* 1760 Spliced UHMWPE 64.5 kN 0.54

4 ^* 25 ^* 1670 Knotted Aramid 16.23 kN 0.20

4 ^* 25 ^* 1670 Spliced Aramid 60.4 kN 0.74

Roundsling of load bearing strands are produced by wrapping multiple turns of an assembled load bearing strand. These strands are assembled by combining the respective amount of yarns as described in Table 2. Typically, a number of yarns is grouped to a bundle of parallel yarns whereby 3 or 4 of these bundles are grouped to form the load bearing strand. When the targeted number of wraps is achieved, the two ends of the load bearing strand are connected by a connecting means. For the comparative examples, knots are used to connect the two ends of the strand to each other. For the examples, a splice is introduced as a connecting means. In case of the splice, a total length of about 200 times the diameter of the strand was laid by splitting each end of the load bearing strand into 4 about equal portions and forming a load bearing strand with two laid ends with 4 sub-strand. In a further step, the laid ends of the strand were spliced (tucked, non-tapered).

EXAMPLE 2

The results reported in Table 2 show that roundslings produced with an end connection with an efficiency higher than 0.40 achieve strength and efficiencies substantially higher (between 8 and 64% in the examples) than roundslings comprising end- connections with lower efficiency.

Table 2

EXAMPLE 3

Roundslings in this example were made as follows

A bundle of 8 x 15 (1760 SK78) yarns was placed around two reels.

The yarns a multifilament yarn parallel having substantially parallel filaments.

The two ends of the bundle were connected to each other by a splice via steps which are schematically depicted in figures 2A - 2D and their description.

Breaking strength of the roundsling of slings with a strength of up to 1000 kN was determined on dry samples using a horizontal tensile tester with a max load capacity of 1000 kN at a temperature of approximately 21 °C, and at a rising force velocity of 150mm/min. The roundslings were tested using a connection pin of 70mm diameter connecting the rounsling to both ends of the machine (pulling end

and static end).

Roundsling tenacity was calculated by dividing the breaking strength of the sling by the titer of the 2 legs of the load bearing core. Covers or coatings are disregarded when assessing the titer.

In the breakload test the break was not at the splice but at an area away from the splice. Results are shown in Table 3

Table 3 Sling construction 8 x 15 (1760 SK78 UHMWPE), single loop

Z-Z splice 100%: the two ends were twisted such that a Z- configuration was obtained, after that the splice as described above was made. The splice had a diameter that was larger than the diameter of each of the twisted ends. Diameter single leg 2.5-3 mm splice diameter: 4.5mm. The total length of the splice was ca 100cm.

Z-S splice 100%: one end was twisted in a Z- configuration, the other end was twisted in a Z- configuration, after that the splice as described above was made. The splice had a diameter that was larger than the diameter of each of the twisted ends.

Z-Z - 50%: the two ends were twisted in a Z-configuration , after that 50% of the yarns of each end were cut away, after that the splice was made as described above. The splice had a diameter that was substantially the same as the diameter of each of the twisted ends.