CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application is related to and claims the priority benefit of U.S. Provisional Patent Application No. 62/892,294, filed August 27, 2019, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

[0002] The present disclosure generally relates to synthetic fiber ropes. More particularly, systems and methods disclosed and contemplated herein relate to synthetic fiber ropes including multiple different synthetic fibers.

INTRODUCTION

[0003] Typically, synthetic rope is made of thousands of individual synthetic fibers.

Synthetic ropes have applications in a variety of industries and are subjected to differing environmental stresses and conditions. In some applications, synthetic fiber ropes can be subjected to conditions involving large stresses, such as loads in excess of 50 Te.

[0004] As an example, synthetic fiber ropes can be used as a towline for tugboats. Conventional tugboats have a fixed tying platform referred to as an “H-bitt,” in which one end of the rope is “tied” to the H-bitt on the tugboat and the other end is connected to a towed vessel. In certain applications, a synthetic fiber rope is wrapped several times around the H-bitt, and an end is laid on the ground. The number of wraps and the coefficient of static friction dictate whether the rope will slip during the towing operation.

[0005] Slippage of the rope may cause bum marks on the H-bitt and/or damage the rope. In extreme cases, the tug boat may disconnect from the towed vessel and thereby lose control of the towed vessel. SUMMARY

[0006] The instant disclosure is directed to synthetic fiber ropes with multiple different fibers. In one aspect, a rope strand is disclosed. The exemplary rope strand includes a set of first fibers arranged in an interior of the rope strand and forming a portion of an exterior of the rope strand and a set of second fibers arranged among the set of first fibers on the exterior of the rope strand. The set of first fibers have a first coefficient of static friction against a steel and the set of second fibers have a second coefficient of static friction against the steel, where the second coefficient of static friction is greater than the first coefficient of static friction. The set of first fibers and the set of second fibers extend continuously along a length of and between opposite ends of the rope strand.

[0007] In another aspect, a rope is disclosed. The exemplary rope includes a plurality of braided rope strands. Each braided rope strand includes a set of first fibers arranged in an interior of each braided rope strand and forming a portion of an exterior of each braided rope strand and a set of second fibers arranged among the set of first fibers on the exterior of each braided rope strand. The set of first fibers have a first coefficient of static friction against a steel and the set of second fibers have a second coefficient of static friction against the steel, and the second coefficient of static friction is greater than the first coefficient of static friction. The set of first fibers and the set of second fibers extend continuously along a length of and between opposite ends of each braided rope strand. A specific gravity of the rope is no less than 0.98 and no greater than 1.025

[0008] In another aspect, a method of making a braided rope is disclosed. The exemplary method includes forming a plurality of rope strands and braiding a plurality of rope strands together to form the braided rope. Each of the plurality of rope strands includes a set of first fibers arranged in an interior of the rope strand and forming a portion of an exterior of the rope strand and a set of second fibers arranged among the set of first fibers on the exterior of the rope strand. The set of first fibers have a first coefficient of static friction against a steel and the set of second fibers have a second coefficient of static friction against the steel, where the second coefficient of static friction is greater than the first coefficient of static friction. The set of first fibers and the set of second fibers extend along a length of and between opposite ends of the rope strand. A specific gravity of the braided rope is no less than 0.98 and no greater than 1.025.

[0009] There is no specific requirement that a material, technique or method relating to synthetic fiber ropes include all of the details characterized herein in order to obtain some benefit according to the present disclosure. Thus, the specific examples characterized herein are meant to be exemplary applications of the techniques described, and alternatives are possible.

[0010] Other independent aspects of the disclosure may become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 shows an exploded view of an embodiment of a rope made according to the present disclosure.

[0012] FIG. 2 shows an embodiment of a holly board arrangement for making an example rope strand.

[0013] FIG. 3 shows another embodiment of a holly board arrangement for making an example rope strand.

[0014] FIG. 4 shows another embodiment of a holly board arrangement for making an example rope strand.

[0015] FIG. 5 shows another embodiment of a holly board arrangement for making an example rope strand.

DETAILED DESCRIPTION

[0016] Systems and methods disclosed and contemplated herein relate to synthetic fiber ropes having multiple different synthetic fibers. Generally, most synthetic fibers in the ropes are of a first fiber type and a minority of the synthetic fibers are of a second fiber type, where the second fiber type has a greater coefficient of static friction against steel. Typically, the second fiber type is only positioned on an exterior portion of the rope strands included in the rope. [0017] Synthetic fiber ropes disclosed and contemplated herein differ from existing ropes in a variety of ways. For instance, some conventional ropes use a coating with a higher coefficient of static friction than standard polyurethane-based coatings. Although those coatings improve the coefficient of friction properties of the rope, such coatings can make the rope difficult to bend because the fibers are bound together by the coating after the rope was tensioned. Having limited bendability can inhibit (e.g., slow down) wrapping of the rope and make the operation take longer time to complete.

[0018] As another example, some ropes incorporate polyester staple yarn into high modulus strands during twisting. However, the pieces of polyester staple yarn are not continuous and the rope sheds during use. Additionally, the polyester fibers do not contribute to the strength of the rope and accordingly add weight to the line.

I. Definitions

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the present document, including definitions, will control. Example methods and materials are described below, although methods and materials similar or equivalent to those described herein can be used in practice or testing of the present disclosure. The materials, methods, and examples disclosed herein are illustrative only and not intended to be limiting.

[0020] The terms “comprise(s),” “include(s),” “having,” “has,” “can,” “contain(s),” and variants thereof, as used herein, are intended to be open-ended transitional phrases, terms, or words that do not preclude the possibility of additional acts or stmctures. The singular forms “a,” “an” and “the” include plural references unless the context clearly dictates otherwise. The present disclosure also contemplates other embodiments “comprising,” “consisting of’ and “consisting essentially of,” the embodiments or elements presented herein, whether explicitly set forth or not.

[0021] For the recitation of numeric ranges herein, each intervening number there between with the same degree of precision is explicitly contemplated. For example, for the range of 6-9, the numbers 7 and 8 are contemplated in addition to 6 and 9, and for the range 6.0-7.0, the number 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, and 7.0 are explicitly contemplated.

[0022] The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (for example, it includes at least the degree of error associated with the measurement of the particular quantity, manufacturing tolerances, etc.). The modifier “about” should also be considered as disclosing the range defined by the absolute values of the two endpoints. For example, the expression “from about 2 to about 4” also discloses the range “from 2 to 4.” The term “about” may refer to plus or minus 10% of the indicated number. For example, “about 10%” may indicate a range of 9% to 11%, and “about 1” may mean from 0.9-1.1. Other meanings of “about” may be apparent from the context, such as rounding off, so, for example “about 1” may also mean from 0.5 to 1.4.

II. Exemplary Ropes

[0023] Exemplary ropes disclosed and contemplated herein can have various constructions and sizes. Certain aspects of exemplary ropes are discussed in the section below.

[0024] FIG. 1 shows an example rope 10. The rope 10 may be a braided rope, a wire-lay rope, or a parallel strand rope. Braided ropes are formed by braiding or plaiting the ropes together as opposed to twisting them together. Braided ropes are inherently torque-balanced because an equal number of strands are oriented to the right and to the left.

[0025] Wire-lay ropes are made in a similar manner as wire ropes, where each layer of twisted strands is generally wound (laid) in the same direction about the center axis. Wire-lay ropes can be torque-balanced only when the torque generated by left-laid layers is in balance with the torque from right-laid layers.

[0026] Parallel strand ropes are an assemblage of smaller sub-ropes held together by a braided or extruded jacket. The torque characteristic of parallel strand ropes is dependent upon the sum of the torque characteristics of the individual sub-ropes.

[0027] In FIG. 1, the rope 10 consists of a plurality of braided strands 12. The braided strands 12 are made by braiding together twisted yarns 14. In some implementations, the strands 12 have no jackets. The twisted yams 14 comprise a first fiber bundle 16 and a second fiber bundle 18. Further information on the stmcture of these ropes may be found in U.S. Patent Nos. 5,901,632 and 5,931,076, the entire contents of which are hereby incorporated by reference.

[0028] A specific gravity of exemplary ropes is such that the rope 10 floats in most salt water environments, where the salt water typically has a density of about 1020 kg/m ³ to about 1029 kg/m ³ . A specific gravity of exemplary ropes is typically no less than about 0.98 and no greater than about 1.025. In various instances, the specific gravity of the rope is no less than 1.00 and no greater than 1.02; no less than 0.98 and no greater than 1.01; no less than 1.008 and no greater than 1.025; no less than 1.005 and no greater than 1.015; no less than 1.015 and no greater than 1.025.

[0029] In some instances, exemplary ropes have a coating that may be applied after the rope is formed and tensioned. In some instances, exemplary coatings may increase abrasion resistance. In some instances, exemplary coatings may increase ultraviolet (UV) light resistance. In some instances, exemplary coatings may add friction to aid holding of splices.

[0030] Example coatings include polyurethane-based coatings. Exemplary polyurethane- based coatings may have a solids percentage of 29.5% to 32.5%. Exemplary polyurethane-based coatings may have a viscosity of 500 cPs to 800 cPs. Exemplary polyurethane-based coatings may have a pH of 8.20 to 9.80. A commercially available polyurethane coating is the RU-40-499 200 kg Permutex from Stahl USA (Peabody, MA).

[0031] Exemplary ropes can have various strand arrangements. For instance, exemplary ropes can be 12x12 strand braided ropes, 12 strand braided ropes, 8 strand braided ropes, 3 strand braided ropes, 12x3 strand braided ropes, and double twisted ropes.

[0032] Exemplary ropes can have different sizes, which can be selected based on intended uses of the ropes as well as strand arrangements. As examples, for 12x12 strand braided rope implementations, a rope diameter can be from about 1.5 inches to about 7.5 inches; from 1.5 inches to 4 inches; from 4 inches to 7.5 inches; from 1 5/8 inches to 3 ¼ inches; from 2 inches to 5 inches; or from 3 1/14 inches to 7.5 inches. [0033] As examples, for 12 strand braided rope implementations, a rope diameter can be from about ¾ inch to about 2 inches; from 1 inch to 1 ¾ inches; from ¾ inch to 1.5 inches; or from 1 inch to 2 inches.

[0034] Exemplary ropes can be used in various industries and for various applications. For instance, exemplary ropes can be used as towing or tug lines, mooring and docking lines, and lifting lines, to name a few examples.

[0035] In some instances, strands in exemplary ropes that are clockwise twist (“S strands”) have a different color than counterclockwise twist strands (“Z strands”). In those implementations, the different colors for the S strands and the Z strands can facilitate a user determining whether a twist is in the rope so the user can remove the twist before using the rope.

III. Exemplary Rope Fibers

[0036] As mentioned above, example ropes described and contemplated herein include first fibers and second fibers. Various aspects of exemplary first fibers and second fibers are discussed below.

[0037] Exemplary first fibers can be selected for various physical properties. For instance, first fibers can be selected for the abrasion resistance, tenacity, ultraviolet damage resistance, and environmental effect resistance.

[0038] In some instances, the first fibers are high modulus polyethylene (HMPE) fibers. HMPE fibers may be spun from ultrahigh molecular weight polyethylene (UHMWPE) resin. Commercially available examples of HMPE fibers include SPECTRA® fibers from Honeywell, and DYNEEMA® from DSM NV of Heerlen, The Netherlands.

[0039] Exemplary first fibers have a coefficient of static friction against steel that is about 0.06 to about 0.09. In various instances, the coefficient of static friction of exemplary first fibers against steel is from 0.06 to 0.09; from 0.06 to 0.08; from 0.07 to 0.09; or from 0.07 to 0.08.

[0040] Exemplary second fibers can be selected for various physical properties. For instance, second fibers can be selected for the relative coefficient of static friction, modulus, specific gravity, to name a few examples. [0041] In various implementations, the second fibers are one or more of: liquid crystal polymer fibers, aramid fibers, polyphenylene benzobisoxazole fibers, texturized polyester (also referred to as textured polyester), and thermotropic polymer fibers. Commercially available examples of second fibers include KEVLAR® from Dupont (Wilmington, Del.), VECTRAN® from Kuraray Co. (Tokyo, Japan), Multiplex from TSI Yarns (Martinsville, Virginia), and TECHNORA® from Teijin Ltd. (Osaka, Japan).

[0042] Exemplary second fibers have a coefficient of static friction against steel that is about 0.16 to about 0.2. In various instances, the coefficient of static friction of exemplary second fibers against steel is from 0.16 to 0.2; from 0.16 to 0.18; from 0.18 to 0.20; from 0.17 to 0.19; from 0.16 to 0.19; or from 0.17 to 0.2.

[0043] Relatively, the coefficient of static friction for the exemplary second fibers is greater than the coefficient of static friction for the exemplary first fibers, when comparing against the same material, such as steel. In various implementations, the coefficient of static friction for the exemplary second fibers is 1.5 times; 2.0 times; 2.5 times; or 3 times greater than the coefficient of static friction for the exemplary first fibers.

[0044] In some implementations, a Young’s modulus of exemplary first fibers may be greater than a Young’s modulus of exemplary second fibers. In some instances, a Young’s modulus of exemplary first fibers may be from 70 GPa to 140 Gpa. In some instances, a Young’s module of exemplary second fibers may be from 90 GPa to 140 GPa; from 75 GPa to 110 GPa; from 110 GPa to 140 GPa; or from 70 GPa to 80 GPa.

[0045] In some implementations, a Young’s modulus of the exemplary first fibers may be no more than 20% greater than; no more than 30% greater than; no more than 40% greater than; no more than 50% greater than; or no more than 60% greater than a Young’s modulus of the exemplary second fibers.

[0046] In some implementations, a Young’s modulus of the exemplary first fibers may be less than exemplary second fibers. As an example, when first fibers are HMPE and when second fibers are polyester, the Young’s modulus of the second fibers may be greater, such as 3-5 times greater, than the Young’s modulus of the first fibers. [0047] In some implementations, a tenacity of exemplary first fibers may be greater than a tenacity of exemplary second fibers. In some instances, a tenacity of exemplary first fibers may be 2.8 Gigapascal (GPa) to 3.9 GPa. In some instances, a tenacity of exemplary second fibers may be from 3.0 GPa to 3.3 GPa; from 3.3 GPa to 3.9 GPa; or from 3.2 GPa to 3.4 GPa.

[0048] In some implementations, a tenacity of exemplary second fibers may be 0.37 GPa to 0.55 GPa. In various instances, exemplary second fibers may have a tenacity of 0.37 GPa to 0.55 GPa; 0.37 to 0.46 GPa; 0.46 GPa to 0.55 GPa; 0.37 GPa to 0.42 GPa; 0.42 GPa to 0.47 GPa; 0.47 GPa to 0.52 GPa; or 0.50 GPa to 0.55 GPa.

[0049] In some implementations, an elongation at break of exemplary second fibers may be 10% to 14%. In various instances, exemplary second fibers may have an elongation at break of 10% to 12%; 12% to 14%; or 11% to 13%. In some implementations, an elongation at break of exemplary second fibers may be 3% to 4%.

[0050] In some implementations, a tenacity of the exemplary first fibers may be no more than 5% greater than; no more than 10% greater than; no more than 15% greater than; no more than 20% greater than; no more than 25%; or no more than 30% greater than a tenacity of the exemplary second fibers. In some implementations, a tenacity of the exemplary first fibers may be less than exemplary second fibers. As an example, when first fibers are HMPE and when second fibers are polyester, a tenacity of the second fibers may be 3-4 times greater than the tenacity of the first fibers.

[0051] By weight, exemplary ropes have more first fibers than second fibers. For instance, exemplary ropes may include no less than about 84% and no more than about 95% by weight first fibers. In various implementations, first fibers account for 84 wt% to 95 wt%; 84 wt% to 89 wt%; 89 wt% to 95 wt%; 84 wt% to 87 wt%; 87 wt% to 90 wt%; 90 wt% to 93 wt%; 92 wt% to 95 wt%; 87 wt% to 92 wt%; 84 wt% to 92 wt%; or 88 wt% to 93 wt% of exemplary ropes.

IV. Exemplary Strand Configurations

[0052] As discussed in greater detail above, exemplary ropes include strands, where some strands include first fibers and second fibers. Various configurations and relative arrangements of first fibers and second fibers in the strands are possible. [0053] Typically, first fibers are arranged both in an interior portion and on an exterior portion of exemplary rope strands. Second fibers are typically arranged only on a portion of the rope strand exterior. Put another way, exemplary ropes may not have any second fibers arranged in an interior portion. In that way, the second fibers can improve coefficient of static friction properties of the strands by being on the exterior of the rope strand, where the second fibers would have little or no effect if positioned on an interior of the rope strand.

[0054] On an exterior of exemplary rope strands, typical implementations include a greater amount of first fibers than second fibers by volume. In various implementations, a ratio of the first fibers to the second fibers on an exterior of a rope strand is 3:1; 3.5:1; 2.5:1; 4:1; or 2:1 by volume.

[0055] On an exterior of exemplary rope strands, typical implementations have ends of first fibers positioned between ends of second fibers. That is, typically, two ends of second fibers are not adjacent to each other on an exterior of a rope strand. In various implementations, every second, third, fourth, or fifth end of twisted fiber on exemplary rope strand exteriors is a second fiber.

[0056] FIGS. 2-6 show various exemplary configurations of holly boards that may be used during manufacture of exemplary rope strands. In turn, the exemplary rope strands may be used in rope manufacture.

[0057] FIG. 2 shows example holly board plate 200. As shown, the holly board plate 200 is configured to be used in making a rope strand including 49 fiber ends. The holly board plate 200 defines an exterior portion 202 and an interior portion 204 for the rope strand.

[0058] The exterior portion 202 includes first fiber end slots 206 and second fiber end slots 208. As shown, the interior portion 204 does not include any second fiber end slots 208. As shown, the exterior portion 202 has a repeating pattern of two first fiber end slots 206 for each second fiber end slot 208.

[0059] FIG. 3 shows example holly board plate 300 arrangement. As shown, the holly board plate 300 is configured to be used in making a rope strand including 56 fiber ends. The holly board plate 300 defines an exterior portion 302 and an interior portion 304 for the rope strand. [0060] The exterior portion 302 includes first fiber end slots 306 and second fiber end slots 308. As shown, the interior portion 304 does not include any second fiber end slots 308. As shown, the exterior portion 302 has a repeating pattern of two first fiber end slots 306 for each second fiber end slot 308.

[0061] FIG. 4 shows example holly board plate 400 arrangement. As shown, the holly board plate 400 is configured to be used in making a rope strand including 62 fiber ends. The holly board plate 400 defines an exterior portion 402 and an interior portion 404 for the rope strand.

[0062] The exterior portion 402 includes first fiber end slots 406 and second fiber end slots 408. As shown, the interior portion 404 does not include any second fiber end slots 408. As shown, the exterior portion 402 has a repeating pattern of two first fiber end slots 406 for each second fiber end slot 408.

[0063] FIG. 5 shows example holly board plate 500 arrangement. As shown, the holly board plate 500 is configured to be used in making a rope strand including 142 fiber ends. The holly board plate 500 defines an exterior portion 502 and an interior portion 504 for the rope strand.

[0064] The exterior portion 502 includes first fiber end slots 506 and second fiber end slots 508. As shown, the interior portion 504 does not include any second fiber end slots 508. As shown, the exterior portion 502 has a repeating pattern of two first fiber end slots 506 for each second fiber end slot 508.

V. Exemplary Method of Manufacture

[0065] Ropes disclosed and contemplated herein can be manufactured according to known techniques.

[0066] An example method of making a braided rope may include forming a plurality of rope strands and braiding the plurality of rope strands together to form the braided rope. Forming the plurality of rope strands can include blending together first fibers and second fibers using an “eye board” or a “holly board.”

[0067] As mentioned above, different numbers of rope strands may be braided together as desired, such as from 6 strands to 14 strands; 8 strands to 12 strands; 10 strands to 14 strands; 6 strands to 10 strands; or 8 strands to 10 strands. After braiding the rope strands together, the rope may be impregnated with a water sealant and/or lubricant coating. In some instances, the coating is polyurethane.

[0068] Each of the plurality of rope strands include a set of first fibers arranged in an interior of the rope strand and forming a portion of an exterior of the rope strand. Each of the plurality of rope strands also include a set of second fibers arranged among the set of first fibers on the exterior of the rope strand.

[0069] The set of first fibers and the set of second fibers extend along a length of and between opposite ends of the rope strand. Typically, the first fibers and second fibers extend continuously along the length of the rope strand. The set of first fibers have a first coefficient of static friction against a steel and the set of second fibers have a second coefficient of static friction against the steel, where the second coefficient of static friction is greater than the first coefficient of static friction.

VI. Experimental Testing

[0070] Exemplary embodiments of ropes were manufactured and tested. For comparison, these exemplar}' ropes were compared against ropes falling outside of the scope of the ropes disclosed and contemplated herein.

[0071] More specifically, ropes including HMPE as first fibers and liquid crystal polymer as second fibers (VECTRAN® from Celanese Advanced Materials, Inc. (Charlotte, N.C.)) were compared to: (i) ropes with only HMPE fibers, (ii) ropes with HMPE as first fibers and spun polyester as second fibers, and (iii) ropes with HMPE as first fibers and continuous filament polyester.

[0072] One-inch diameter ropes were made using each of the four fiber designs. Then, the rope was wrapped around a metal post and the force required to cause the rope to slip was recorded. Three tests were conducted for each rope and for a given number of wraps. The resulting data are shown in Table 1, below. Table 1. Force required to cause a rope to slip from a metal post, where each rope was tested three times with 3, 4, and 5 wraps around the post.

[0073] As shown in Table 1, of the four different rope types tested, the HMPE and Liquid Crystal Polymer rope required the highest pulling tension to cause slippage for 3 wraps, 4 wraps, and 5 wraps.

[0074] The foregoing detailed description and accompanying examples are merely illustrative and are not to be taken as limitations upon the scope of the disclosure. Various changes and modifications to the disclosed embodiments will be apparent to those skilled in the art. Such changes and modifications, including without limitation those relating to the chemical structures, substituents, derivatives, intermediates, syntheses, compositions, formulations, or methods of use, may be made without departing from the spirit and scope of the disclosure. [0075] One or more independent features and/or independent advantages of the invention may be set forth in the claims.