EP3783149B1

EP3783149B1 - Method for manufacturing a fibrous rope, and corresponding fibrous rope

Info

Publication number: EP3783149B1
Application number: EP19382716.9A
Authority: EP
Inventors: François MOUCHET
Original assignee: Intermas Nets SA
Current assignee: Intermas Nets SA
Priority date: 2019-08-19
Filing date: 2019-08-19
Publication date: 2023-07-12
Anticipated expiration: 2039-08-19
Also published as: EP3783149C0; EP3783149A1; ES2950652T3

Description

Field of the Invention

The invention relates to a method of manufacturing a rope formed by a plurality of filaments, and to a rope which can be obtained by means of said manufacturing method.

State of the Art

Conventional rope manufacturing methods consist of twisting a plurality of filaments together to form a strand, and then twisting or braiding said strands together to form the rope or cords which are in turn twisted or braided to form the rope.
In these conventional rope manufacturing methods, the step of forming the strands is complex as there is a need to handle a large amount of filaments with a relatively small diameter. These filaments are driven by a system consisting of reels and rollers, which adjust the tautness of the filaments and keep them separated so that they do not become tangled, to a twisting machine, in which the filaments are twisted together to form the strand. This method of forming the strands, and accordingly a rope made of said strands, is laborious and complex because filaments of very small diameter which may become damaged and/or tangled are handled individually.
US2015152593A1 and US3380243A disclose different methods of manufacturing a rope according to the preamble of claim 1, in which the twisted mesh is a polymer fibrillated tape.
GB1232450A discloses a method of manufacturing strings for rackets, in which a strand is formed by twisting a polymer fibrillated tape.
US3273329A discloses a method of manufacturing a textile yarn, in which a strand is formed by twisting a polymer fibrillated tape.

Description of the Invention

The purpose of the invention is to provide a method of manufacturing a rope formed by a plurality of strands of filaments, the practical implementation of which is easier than that of conventional methods, without thereby compromising the physical and mechanical characteristics of the rope that is obtained.
Another objective of the invention is to provide a rope formed by a plurality of strands of filaments, which is more robust than ropes obtained by means of the conventional manufacturing methods.
This purpose is achieved by means of a method of manufacturing a rope according to claim 1.
The use of a mesh to form a strand of the rope constitutes a notable simplification with respect to the conventional rope manufacturing methods because it prevents having to handle a plurality of independent filaments that must be arranged in a specific manner required for forming a strand from said filaments. In fact, in the method according to the invention, a strand of the rope is formed by simply twisting a mesh. The mesh is formed by a plurality of filaments, but these filaments are attached to one another at their intersecting points in the mesh, so it is not necessary to handle them individually. Furthermore, a rope obtained by means of the method according to the invention is more robust than a rope obtained by means of a conventional method, because the filaments of the twisted mesh forming a strand are attached to one another at their intersecting points. If breakage of one of the filaments of this strand occurs while using the rope, said breakage does not at all affect the constitution of the strand or the characteristics of the rope, because the filament that broke is still attached to the other filaments of the strand through the intersecting points between the filaments of the mesh.
The mesh which is provided in step [a] and twisted in step [b] to form the strand of twisted mesh can be a woven mesh, in which case the filaments of the mesh are attached to one another by means of weaving at their intersecting points.
In the preferred embodiments, said mesh is an extruded mesh, in which the filaments of one of said two bundles are attached to the filaments of the other one of said two bundles at the intersecting points by means of fusion of the material forming said filaments. A more compact and homogenous strand is thus obtained, and therefore a more robust rope with a more precise shape is also obtained.
Preferably, the extruded mesh which is provided in step [a] and twisted in step [b] to form the strand of twisted mesh is a mesh in which the filaments of the two bundles of filaments and the intersecting points have one and the same thickness. This mesh can be, for example, a mesh hot-flattened at the outlet of the extruder, obtained by means of the method described in document EP2006077B1 . Even more compact and robust strands of twisted mesh are thereby created because the mesh has no protuberances at the intersecting points of the filaments.
Preferably, said extruded mesh which is provided in step [a] and twisted in step [b] to form the strand of twisted mesh is a tubular mesh. In twisting step [b], a tubular mesh is easier to handle than a flat mesh. Advantageously, the tubular mesh can be stretched in the longitudinal direction thereof before twisting, thereby obtaining a shape similar to the shape of a rope. This allows twisting using conventional equipment or equipment with inexpensive adaptations. Furthermore, by using a tubular mesh a strand of twisted mesh with a more homogenous shape is obtained. Another advantage is that extruded meshes usually already have a tubular shape at the outlet of the extruder.
The mesh which is provided in step [a] and twisted in step [b] to form the strand of twisted mesh can be a mesh of extruded filaments of any thermoplastic suitable for forming extruded filaments. For example, the thermoplastic forming the filaments of the extruded mesh can be one selected from the group consisting of:

a synthetic polymer, preferably one selected from the group consisting of polyethylene (PE) and polypropylene (PP);
a synthetic copolymer, preferably a polyethylene (PE) and polypropylene (PP) copolymer;

an elastomer;
a mixture of at least two of the above.

In some advantageous embodiments, the mesh which is provided in step [a] and twisted in step [b] to form the strand of twisted mesh is a mesh of filaments of a material that can be extruded to form the filaments, comprising at least one biodegradable thermoplastic. In particularly advantageous embodiments, said mesh is an extruded mesh in which the filaments are attached at the intersecting points by means of fusion of the material forming said filaments. This allows manufacturing a rope made entirely or partially from a biodegradable thermoplastic by means of a method that is much more reliable than the known methods. In fact, in the known methods the strands of the rope are formed by means of twisting or braiding a plurality of independent filaments together, and each of these filaments must be obtained individually in an extrusion line. Extruding a filament of biodegradable thermoplastic, or an extrudable material comprising a biodegradable thermoplastic, is a delicate process, because a high temperature is required in the extruder, and this high temperature degrades the properties of the biodegradable thermoplastic. In contrast, to manufacture an extruded mesh, a lower extrusion temperature, which does not negatively affect the properties of the biodegradable thermoplastic, is required. A rope made with biodegradable thermoplastic is of special interest for reducing environmental impact in cases in which the rope may constitute waste. For example, it is special interest in the field of oyster farming in which the rope, or a rig manufactured with same, may be lost to the sea.
In some embodiments, said biodegradable thermoplastic is one selected from the group consisting of polylactic acid (PLA), polyhydroxybutyrate (PHB), polyhydroxyvalerate (PHV), polybutylene succinate (PBS), polycaprolactone (PCL), polybutylene adipate terephthalate (PBAT), polyvinyl alcohol (PVOH), a starch-derived bioplastic. The starch-derived bioplastic can be, for example, a corn, potato, wheat, or cassava starch-derived bioplastic.
Optionally, the extrudable material forming the filaments of the mesh may contain, in addition to a thermoplastic, additives and/or dyes. When the thermoplastic is a biodegradable thermoplastic, it is preferably mixed with a biodegradable additive based on a compound with a high mineral content, such as calcium carbonate, talc, kaolin, mica, or glass fiber, for example.
In some embodiments, the composition of a plurality of strands of the rope formed in step [c] consists of at least one strand of twisted extruded mesh of an extrudable material comprising at least one biodegradable thermoplastic, formed in step [b], and at least one strand of natural fibers. Preferably, these natural fibers are of plant origin, for example, cotton, flax, hemp, coconut, kapok, jute, sisal, or abaca fibers. The fibers can also be of animal origin, for example, sheep wool, alpaca wool, or silk. A composition consisting of strands of twisted extruded mesh having a biodegradable thermoplastic and of strands of natural fibers allows obtaining a rope with good mechanical properties and a lower environmental impact.
The invention also relates to a rope which can be obtained by means of the manufacturing method described above.
The rope according to the invention is a rope as defined in claim 7.
Preferably, the mesh forming the strand of twisted mesh is an extruded mesh in which the filaments of one of the two bundles are attached to the filaments of the other one of the two bundles at the intersecting points by means of fusion of the material forming said filaments.
Preferably, the mesh forming the strand of twisted mesh is a mesh in which the filaments of the two bundles of filaments and the intersecting points have one and the same thickness.
Preferably, the mesh forming the strand of twisted mesh is a tubular mesh.
In advantageous embodiments, the mesh forming the strand of twisted mesh is an extruded mesh of a biodegradable thermoplastic. This biodegradable thermoplastic is any of those mentioned above in the description of the method.
In advantageous embodiments, the composition of a plurality of strands of the rope consists of at least one strand of twisted extruded mesh of an extrudable material comprising at least one biodegradable thermoplastic, and at least one strand of natural fibers. These natural fibers are any of those mentioned above in the description of the method.
The invention also covers other detailed features illustrated in the detailed description of an embodiment of the invention and in the attached drawings.

Brief Description of the Drawings

Other advantages and features of the invention will become apparent from the following description in which preferred embodiments of the invention are described in a non-limiting manner in reference to the attached drawings.

Figure 1 is a schematic view of a segment of a tubular mesh with which the strands of a rope according to the invention can be formed.
Figure 2 is an enlarged view of an area of the tubular mesh of Figure 1.
Figure 3 is a more enlarged view of an area of the tubular mesh of Figure 1.
Figure 4 is an enlarged view of an area of another tubular mesh with which the strands of a rope according to the invention can be formed.
Figure 5 is a schematic depiction of an embodiment of step [b] of the method according to the invention, in which the tubular mesh of Figure 1 is being twisted to form a strand of twisted mesh.
Figure 6 is a schematic depiction of an embodiment of step [c] of the method according to the invention, in which a composition is being made from a plurality of strands of twisted mesh, formed in the preceding step, for obtaining a rope according to the invention.
Figure 7 is a view of a rope according to the invention, formed by means of braiding strands of twisted mesh.
Figure 8 is a view of another rope according to the invention, formed by means of twisting strands of twisted mesh.
Figure 9 is a view of another rope according to the invention, formed by means of twisting cords that are in turn formed by means of braiding strands of twisted mesh.

Detailed Description of Several Embodiments according to the Invention

The method of manufacturing a rope 1 according to the invention and the rope 1 obtained therewith have, as an essential feature, the use of a mesh 2 twisted to form a strand 5 of said rope 1.
The mesh 2 is a mesh of a known type formed by bundles of extruded filaments 3 extending in different directions and intersecting with one another at intersecting points 4. The filaments 3 of one of the bundles are attached to the filaments 3 of the other bundle at intersecting points 4. Figures 1 to 3 show an example of a mesh 2 used in the method. In the case depicted by way of example in these figures, the mesh 2 is an extruded tubular thermoplastic mesh, in which the filaments 3 of one of the bundles are attached to the filaments 3 of the other bundle at intersecting points 4 by means of fusion of the thermoplastic forming said filaments 3. The mesh 2 forms a diamond-shaped weft of filaments 3, like the one shown in Figure 2, and was hot-stretched in its longitudinal direction. Furthermore, the mesh 2 was preferably hot-flattened to prevent the excessive thickness created at the outlet of the extruder at intersecting points 4, such that the filaments 3 of the two bundles and the intersecting points 4 have one and the same thickness, as can be seen in Figure 4. The mesh 2 can also have, for example, a rectangular- or square-shaped weft of filaments 3, like the one shown in Figure 4. The method of manufacturing meshes 2 of this type, like those shown in Figures 1 to 4, is known by one skilled in the art. It is described, for example, in document EP2006077B1 .
Figure 5 schematically shows the process of twisting the mesh 2 to form a strand 5 of twisted mesh. This process of twisting the mesh 2 does not present any technical difficulties; it can be performed by means of a known installation of the types conventionally used for twisting strands and cords in industrial rope manufacture. Preferably, the tubular mesh 2 is first stretched in the longitudinal direction thereof so that it adopts a more compact shape, and the said mesh 2 is twisted around an axis coinciding with the longitudinal direction thereof.
The twist applied (number of turns applied per unit of length) in the strand 5 of mesh 2 depends on the compactness to be achieved and on the type of mesh 2 used, particularly the number of filaments 3 and the thickness thereof. In any case, the strand 5 thus obtained has a consistency that is better than the consistency of a strand formed by means of a conventional method of twisting a plurality of independent filaments together.
As shown in Figure 6, the strands 5 of twisted mesh obtained in the preceding step are arranged in moving reels 7 of an installation 8 for manufacturing ropes by means of braiding or twisting the strands. This installation 8 can be a conventional installation for manufacturing ropes, with the difference that each reel 7, instead of being loaded with a strand formed by independent filaments twisted together, is loaded with a strand 5 of twisted mesh, formed by twisting a mesh 2 as described above. In a known manner, the reels 7 move following predetermined movements for forming a rope 1 by braiding or twisting the strands loaded in said reels 7. In the invention, as mentioned, these strands are strands 5 of twisted mesh. The rope 1 is thereby formed by making a composition from strands 5 of twisted mesh, wherein said composition can be a twist, a braid, and a combination of twist and braid, depending on the movements of the reels 7.
Figures 7, 8, and 9 show, by way of example, three ropes 1 according to the invention which can be obtained by means of the method described above. The rope 1 of Figure 7 is formed by several strands 5 of twisted mesh braided together. The rope 1 of Figure 8 is formed by several strands 5 of twisted mesh twisted together. The rope 1 of Figure 9 is formed by several cords 6 twisted together, and each of these cords 6 is formed by a plurality of strands 5 of twisted mesh braided together.
Various other embodiments of a rope according to the invention, in which the rope has at least one composition of a plurality of strands consisting of a twist, a braid, or a combination of braid and twist, and at least one of said strands of the composition is a strand 5 of twisted mesh, are possible. The rope can have other elements, such as a cover, a core, as well as other strands that are not a strand of mesh, for example.
The extrudable material forming the mesh 2 forming the strand 5 of twisted mesh can be any of those indicated above in the description of the invention. For example, it can be polyethylene (PE), among other possibilities. Preferably, it is an extrudable material that contains a biodegradable thermoplastic and may have additives and/or dyes. For example, said extrudable material can have the following composition by weight: 80% of polylactic acid (PLA) and 20% of an additive with a high mineral content. For example, the additive is a masterbatch with the following composition by weight: 80% of calcium carbonate and 20% of polyhydroxyalkanoate (PHA).
Advantageously, the composition of a plurality of strands in a rope 1 can combine one or more strands 5 of twisted extruded mesh of an extrudable material comprising a biodegradable thermoplastic and one or more strands of natural fibers, preferably fibers of plant origin. For example, in some embodiments, some of the strands of the ropes 1 shown in the drawings are strands 5 of twisted extruded mesh of an extrudable material containing a biodegradable thermoplastic, for example the material indicated above (80% of PLA and 20% of additive compound by 80% of calcium carbonate and 20% of PHA), whereas other strands of the same rope 1 are strands of natural fiber, for example coconut fiber.

Claims

A method of manufacturing a rope (1) formed by a plurality of strands of filaments, comprising the following steps:
[a] providing a mesh (2);

[b] twisting said mesh (2) to form a strand (5) of twisted mesh;

[c] forming a rope (1) by making a composition from a plurality of strands (5) including at least said strand (5) of twisted mesh formed in step [b], said composition being one from the group consisting of a twist, a braid, and a combination of twist and braid;
characterized in that, said mesh (2) comprises at least two bundles of extruded filaments (3) extending in different directions and intersecting with one another at intersecting points (4), the extruded filaments (3) of one of said two bundles being attached to the extruded filaments (3) of the other one of said two bundles at said intersecting points (4).
The method according to claim 1, characterized in that said mesh (2) which is provided in said step [a] and twisted in said step [b] to form said strand (5) of twisted mesh is an extruded mesh, in which the filaments (3) of one of said two bundles are attached to the filaments (3) of the other one of said two bundles at said intersecting points (4) by means of fusion of the material forming said filaments (3).
The method according to claim 2, characterized in that said mesh (2) which is provided in said step [a] and twisted in said step [b] to form said strand (5) of twisted mesh is a mesh, in which said filaments (3) of the two bundles of filaments (3) and said intersecting points (4) have one and the same thickness.
The method according to any one of claims 2 or 3, characterized in that said mesh (2) which is provided in said step [a] and twisted in said step [b] to form said strand (5) of twisted mesh is a tubular mesh.
The method according to any one of claims 1 to 4, characterized in that said mesh (2) which is provided in said step [a] and twisted in said step [b] to form said strand (5) of twisted mesh is an extruded mesh of an extrudable material comprising at least one biodegradable thermoplastic.
The method according to claim 5, characterized in that said composition of a plurality of strands of the rope (1) formed in said step [c] consists of at least one strand (5) of twisted extruded mesh of an extrudable material comprising at least one biodegradable thermoplastic, formed in said step [b], and at least one strand of natural fibers.
A rope (1) formed by a plurality of strands of filaments, said rope (1) comprising a composition of a plurality of strands (5), said composition being one from the group consisting of a twist, a braid, and a combination of twist and braid, wherein at least one of said strands (5) of said plurality of strands (5) forming said composition is a strand (5) of twisted mesh, formed by a mesh (2) twisted upon itself, characterized in that said mesh (2) comprises at least two bundles of extruded filaments (3) extending in different directions and intersecting with one another at intersecting points (4), the filaments (3) of one of said two bundles being attached to the filaments (3) of the other one of said two bundles at said intersecting points (4).
The rope (1) according to claim 7, characterized in that said mesh (2) forming said strand (5) of twisted mesh is an extruded mesh, in which the filaments (3) of one of said two bundles are attached to the filaments (3) of the other one of said two bundles at said intersecting points (4) by means of fusion of the material forming said filaments (3).
The rope (1) according to any one of claims 7 or 8, characterized in that said mesh (2) forming said strand (5) of twisted mesh is a mesh in which said filaments (3) of the two bundles of filaments (3) and said intersecting points (4) have one and the same thickness.
The rope (1) according to any one of claims 8 or 9, characterized in that said mesh (2) forming said strand (5) of twisted mesh is a tubular mesh.
The rope (1) according to any one of claims 8 to 10, characterized in that said mesh (2) forming said strand (5) of twisted mesh is an extruded mesh of an extrudable material comprising at least one biodegradable thermoplastic.
The rope (1) according to claim 11, characterized in that said composition of a plurality of strands of the rope (1) consists of at least one strand (5) of twisted extruded mesh of an extrudable material comprising at least one biodegradable thermoplastic, and at least one strand of natural fibers.