Hybrid rope

Abstract

Rope comprising at least one primary base yarn. The at least one primary base yarn comprises high-modulus polyethylene (HMPE) fibers and polyester fibers. The at least one primary base yarn is arranged in a twisted manner.

Description

[0001] TITLE: Hybrid Rope

[0002] FIELD OF THE INVENTION

[0003] Ropes are commonly used in a variety of fields. In the maritime sector, ropes, also called hawsers, are used, for example, for mooring or to connect two boats during a towing operation.

[0004] BACKGROUND OF THE INVENTION

[0005] Solutions are known that use polyamide ropes. A rope comprising polyamide is used for towing at sea. Also known is the rope of EP1954870 comprising a mixture of high-performance polyethylene fibers and polytetrafluoroethylene fibers and the method of EP0974698 for constructing a large-diameter braided rope made of high-strength, low-elongation synthetic fibers that are twisted together according to a determined twist factor.

[0006] However, these solutions are not entirely satisfactory and have a number of drawbacks, particularly in terms of mechanical performance, the volume required for equivalent lengths and the characteristics of lifespan in a marine environment. Polyamide materials degrade in particular when immersed in seawater.

[0007] SUMMARY OF THE INVENTION

[0008] There is a need for ropes with good mechanical performance while ensuring a long service life and high compactness.

[0009] To this end, a rope comprising at least one primary base yarn is described below. Said at least one primary base yarn comprises high modulus polyethylene (HMPE) fibers and polyester fibers. Said fibers are arranged in a twisted manner. This composition makes it possible to obtain good tenacity thanks to the polyethylene fibers while having high elasticity thanks to the polyester fibers. Typically, the rope of the invention has an elasticity of at least 10%, preferably at least 15%, typically 15.5%. The rope also has a breaking strength equivalent to the ropes conventionally used. The coexistence of the two types of fibers is also made possible thanks to the twisted arrangement obtained by twisting the primary base yarn.According to particular embodiments, the rope according to the invention has one or more of the following characteristics, taken in isolation or in all technically possible combinations:

[0010] - the tenacity value of high modulus polyethylene (HMPE) fibers is at least 30CN / dtex. This tenacity threshold provides good mechanical performance, particularly with respect to the loads and impacts applicable to the rope.

[0011] - the at least one primary base yarn comprises from 55% to 65% by mass of high modulus polyethylene (HMPE) fibers and from 35% to 45% by mass of polyester fibers. This makes it possible to achieve aging resistance performance in a marine environment. The assembly of these materials makes it possible to obtain good retention of mechanical performance during immersion in water and an increase in the permissible elongation before rupture.

[0012] - the rope comprises a plurality of primary base yarns twisted together to form at least one secondary base yarn, the at least one secondary base yarn being arranged in a twisted manner in the same direction as the primary base yarns forming it. This allows its tenacity to be maintained relative to the performance of the fibers and its elasticity to be improved.

[0013] - the rope comprises several secondary base yarns braided together so as to form at least one primary braid, a portion of the secondary base yarns being twisted in a first direction and the other portion of the secondary base yarns being twisted in a second direction, opposite to the first direction. The elasticity of the rope is improved on the one hand by double-twisting the primary base yarns, and on the other hand by braiding them. By braiding yarns having a different twist, the elasticity of the braid obtained is significantly improved. Preferably, double-twisting and braiding make it possible to increase the elasticity of the rope by at least 1%, compared to a rope of the same composition which has not been double-twisted and braided, more preferably by 1% to 10%, advantageously by 2% to 5%, typically by 4.5%.

[0014] - the rope is made up of several primary braids braided together,

[0015] - the rope is a towing line.

[0016] BRIEF DESCRIPTION OF THE FIGURES

[0017] Characteristics and advantages of the invention will appear on reading the description which follows, given solely by way of non-limiting example, and made with reference to the appended drawings, in which: [Fig. 1] Figure 1 is a diagram representing the arrangement of a rope according to the invention.

[0018] Figure 1 shows a rope 1 according to the invention. Rope 1 comprises at least one primary base yarn 3. Primary base yarn 3 comprises fibers 2 that are not arranged together. Fibers 2 are arranged in a bundle and all have the same general direction. Primary base yarn 3 comprises fibers 2 of high modulus polyethylene (HMPE) and fibers 2 of polyester. Polyester and high modulus polyethylene retain their properties when immersed in water. This provides good preservation of the integrity of the material and therefore a means of remedying degradation in a marine environment. For example, mechanical performance is maintained for the following environmental conditions: seawater temperature range -1°C < T< 24°C, air temperature -20°C < T < 60°C and humidity 25% < H < 80%.In one embodiment, the tenacity value of the high modulus polyethylene fibers is at least 30CN / dtex (HMPE, “High Modulus Polyethylene”). This tenacity makes it possible to achieve sufficient mechanical performance for a towing operation, for example. In another embodiment, the at least one primary base yarn 3 comprises from 55% to 65% by mass of high modulus polyethylene fibers 2 (HMPE, “High Modulus Polyethylene”) and from 35% to 45% by mass of polyester fibers 2. This composition ensures a good balance between elasticity and tenacity for the primary base yarn 3.

[0019] The primary base yarn 3 is arranged in a twisted manner, that is, it forms a twist. This is achieved with a twisting operation. For example, the base yarn 3 has a first end (not shown) and a second end (not shown), the first end of the base yarn 3 is fixed and the second end is rotated for a given number of turns. The base yarn 3 thus retains the elasticity and elongation at break characteristics of the high modulus polyethylene fibers 2. In one embodiment, the average elongation at break value of an untwisted high modulus polyethylene fiber 2 is 3.5% and that of an untwisted polyester fiber 2 is 22%. The at least one primary base yarn 3 composed of high modulus polyethylene fibers 2 and polyester fibers 2 must have an initial minimum elongation at break property of 10% to ensure the expected mechanical performance.This elongation at break characteristic is improved by at least 4.5% under the effect of twisting the at least one primary base yarn 3. Preferably, the at least one primary base yarn 3 is twisted at a value of between 80 and 120 turns per meter. In the embodiment of Figure 1, the primary base yarn 3 is twisted, i.e. turned on itself at 100 turns per meter in one direction. Preferably, the secondary base yarn 3 is twisted at a value of between 80 and 120 turns per meter. The two twisting directions are respectively called S and Z. A secondary base yarn 4 is an assembly of primary base yarns 3 arranged so as to form a yarn comprising three or four primary base yarns 3, not braided. The secondary base yarn 4 is twisted. The twisting of this secondary base yarn 4 is carried out in the same direction as the primary base yarns 3 which it comprises so as to accumulate the twists and therefore increase the elasticity.Preferably, the secondary base wire 4 is twisted at a value between 80 and 120 turns per meter.

[0020] A primary braid 5 is braided from spindles of secondary base yarns 4, for example 16 spindles, another number of spindles being possible depending on the desired rope diameter. In one embodiment, the secondary base yarns 4 of the primary braid 5 are partly twisted in the S direction and partly twisted in the Z direction. This arrangement makes it possible to obtain good mechanical characteristics for the primary braid 5, in particular elasticity. Preferably, there are the same number of spindles with secondary base yarns 4 twisted in the S direction as there are spindles with secondary base yarns 4 twisted in the Z direction. The rope 1 is finally obtained by braiding primary braids 5. In the embodiment of FIG. 1, the rope 1 is obtained by braiding into 12 spindles of primary braids 5.

[0021] The rope 1 of the invention can be used as a towing line. It can then include metal or non-metal interfaces at its ends to interface with a ship, for example via a shackle. A shackle can thus complete the towing line thus formed.

[0022] In a particular embodiment, the rope 1 is hollow. The primary braids 5 are braided so as to create a void in the center, which improves its compactness while reducing its mass.

Claims

CLAIMS 1. Rope (1) comprising at least one primary base yarn (3) characterized in that said at least one primary base yarn (3) comprises high modulus polyethylene fibers (2) and polyester fibers (2) and in that the fibers (2) of said at least one primary base yarn (3) are arranged in a twisted manner.

2. Rope (1) according to claim 1 characterized in that the tenacity value of the high modulus polyethylene fibers (2) is at least 30CN / dtex.

3. Rope (1) according to one of the preceding claims, characterized in that the at least one primary base yarn (3) comprises from 55% to 65% by mass of high modulus polyethylene fibers (2) and from 35% to 45% by mass of polyester fibers (2).

4. Rope (1) according to any one of the preceding claims, characterized in that it comprises several primary base wires (3) twisted together so as to form at least one secondary base wire (4), the at least one secondary base wire (4) being arranged in a twisted manner in the same direction as the primary base wires (3).

5. Rope (1) according to claim 4, characterized in that it comprises several secondary base threads (4) braided together so as to form at least one primary braid (5), a part of the secondary base threads (4) being twisted in a first direction and the other part of the secondary base threads (4) being twisted in a second direction, opposite to the first direction.

6. Rope (1) according to claim 5, characterized in that it consists of several primary braids (5) braided together.

7. A mooring line characterized in that it comprises a rope (1) according to any one of the preceding claims.

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