Process to manufacture a braided cable, a twine or a cord retordue and to make of it a net, in particular a fishing net.

The present invention generally relates, firstly a process for manufacturing a braided cord, a twine or cord twisted with sealing interstices present between filaments base of the base material, wherein the braiding is carried out, the stranding or twisting around a core of thermoplastic material and subjecting the resulting product to a process which softening or melting of the thermoplastic material of the core. The manufacture of a braided cord, a twine or cord is generally known, and sealing of such a product is effected by application of a coating on its outer surface. Patent of the United States of America no. 2.284.728 describes the use of a, core made of thermoplastic material. This material, after softening, penetrate the interstices between the filaments or wires under the effect of pressure exerted on the outer surface of the cord, the twine or rope.

The coating has the disadvantage that it disappear locally by wear, such disappearance not only detract from the appearance of the cord, the twine or rope, but also to its properties, because it forms a penetration path of undesirable substances such as dirt, sand and similar substances capable of affecting the output materials adversely affecting their flexibility, their strength and dimensional stability.

If use is made of a thermoplastic material - core, the pressure exerted on the outer surface of the string or the like does not ensure a uniform distribution of the core material softened and the junction to the core may be disturbed.

The invention aims to provide a solution to such difficulties and this is achieved, according to the invention, by the fact that the treatment of the product obtained by braiding, twisting or lay a process which is - removal 'of the base material'■while it is held under tension "

If the cord, the twine or cord having a core made of thermoplastic material is held under ' voltage, its' diameter decreases. If the core is. simultaneously maintaining softened or melted by the addition of a plasticizing agent or a heat treatment, the core is' surrounded tightly as a result, the strain imposed on the material which forces the material of the core to penetrate from the inside in the interstices between the ' fibers and, therefore, forming a seal not subject to abrasion from die the outer surface. The pressure exerted by the base material on exchanging skills is effective throughout its extension.

' The invention relates, in particular, to a method of making a thread with nodes' braided cord, twine or rope of twisted made of a fiber material, in particular a shrinkable thermoplastic material, where the thread is obtained, by tying cords to form a network, then heat treating the network stretched condition and by sealing interstices present between filaments structu the base material. It is known generally to make a filefile.t, for example a fishing net, in this way. The basic material used for this purpose is made from yarns having a high strength and a high wear resistance ., as one of polyamide, in particular nylon 6. A hollow cord is preferably braided from these yarns, because such a hollow cord is flexible and can be easily knotted. A network thus obtained is then subjected to a heat treatment usually while being kept or not under tension to secure the nodes and stabilize the material, which means, in particular, that the material undergoes shrinkage. In this way a net having meshes of the same size everywhere having nodes and tightly secured.

When using such a net as fishing net, foreign matter such as sand may be deposited into the voids of the strings in the thread-forming, and it is, in particular, thus-to-when one uses the net as the trawl. The grains of sand into the sheath or the structure of the strings, but supplied by more, thereby inflating portions ropes■and - causes, therefore, length changes which cause changes in the dimension of the cells.

In addition, the grains of the sand within strings contribute to rapid abrasion, because the net is subjected to continual movements, so that the fibers of the thread and the sand grains are continuously moving with friction relative to each other.

To avoid these drawbacks, it is known, it is true, coating the net after manufacture, of PU coating to seal the interstices between the fibers of 1' outside. A dye may be added to the coating.

However, this coating wears after which sand may again enter with the drawbacks mentioned. In addition, the coating wears more quickly at the positions of nodes which form thickened portions and, in the case of a cover comprising a colorant, such wear causes color differences that might impair the effectiveness of the fishing. It is true that certain fish, such as tuna, cannot distinguish colors but distinguish differences in color as a result of which the net which, initially is not visible, becomes visible for these fish and frightening.

The aim of the invention further provide a method of making a thread to nodes that only has the above drawbacks.

According to the invention, this is achieved by the fact that, to form the nodes of the net, use is made of a braided cord, a twine or rope comprising a core of thermoplastic material, the cord, the twine 06665

. or, the rope being tied together to form a network which, by IS; thereafter, shall be subjected, in the tensioned state, to a treatment causes a softening of the web and the sputtering network nodes is tensioned on all sides and is subjected to. thermal treatment during which it is held taut thereby, the heat treatment being such that during the shrinkage of the base material of the cords, the thermoplastic material of the core penetrates the interior in the interstices present between the filaments. the wires.

The tire cord, the twine or cord respectively braided, twisted or cabled, around the core and that does.. not yet processed further to force the material of the core to the exterior still has the flexibility needed to provide the nodes in the network. When, after the network formation by knotting, this network is subjected to, a heat treatment that shrink the fibers etet.qui fuses the core and provided the network is held taut on all sides, the constriction causes an increase of the voltage, so that the parts of the present between the network nodes acquire a more. small diameter and clasp, therefore, die forces the core which therefore penetrates into the interstices between the filaments or threads, for example of the braid, toward the outside. The stress. restriction thus acquired tightens simultaneously the nodes more strongly, so that the material of the core also penetrates to the exterior of these nodes. This displacement of the material of the core from the interior to an exterior for flooding of the filaments and the sealing of the interstices between the wires. The resulting structure is much less prone to wear and prevents the entering of sand. When the core contains a gilding, the disclosed method provides a colored thread which does not have a color differences when uspre by abrasion at the nodes.

It is important that the contraction or shrinkage of the material and the softening and melting of the core are made simultaneously, otherwise areas insufficiently sealed by the material of the core can still be formed near the nodes.

The core is made of a fiber can resist temperatures and forces encountered during the manufacturing process.

The type of fibj * I used is preferably similar to that of the side sheath, it is to say that the core is made of a support wire can resist temperatures and forces encountered during the heat treatment. . Use is preferably made of polyamide or polyester yarn coated with a thermoplastic material such as a polyethylene based polymer. The material, which is to be able to melt and penetrate into the voids or interstices cords during processing restriction, is formed by the thermoplastic material, while the inner wire of polyamide or polyester can then losing its support function. This support function is desirable to insure that the molten core material does not flow on one side, that could lead to uneven sealing.

For making a net, it is known to fix the nodes using a heat treatment. According to the invention, this heat treatment is now applied preferably to a temperature above the shrink temperature of the base material of the cords. This ensures that the attachment nodes can occur only when the material of the nodes has had an opportunity to shrink tightly around the core material melted during the shrinkage.

The invention will be described hereinafter in more détafi^! , with reference to the accompanying drawings, in which:

fig. 1 illustrates a fragment of braided cord according to the invention;

figure 2 illustrates the housing of the fiber core at the center of a strand of twine or rope;

fig. 3 illustrates a fragment of twine or cord comprising a plurality of filament bundles or strands provided with cables of ârnejj

figure 3a is a cross-sectional view of fig. 3, and

fig. 4 illustrates a portion of a network.

Figure 1 represents a braid 1 formed of bundles of filaments' flat indicated at 2, 1 the braid is braided around a core made of inner wire 3, e.g. polyamide, - clad with a layer of thermoplastic coating 4.

It is difficult to the drawings show that, when the inventive treatment is completed, the coating layer 4 has penetrated between the filaments and the interstices of the braid, the braid such that has become coherent and massive would be likely completely colored carburization dye within the coating 4.

Figure 2 illustrates the manufacture of. a twine initially a core yarn 3, 4 and filaments 2.

Figure 3 represents three filament bundles or strands 10, 11 and 12 provided with a core yarn 3, 4 that are assembled to form a cord by stranding.

Fig. 4 illustrates a network comprising cords 5, 6, 7 tied together, the nodes being indicated by the numerals 8 and 9 de reference, respectively.

The melting temperature of coating 4 and the temperature of rétrécisseme's filaments 2 must be in agreement with each other. When using a. network made from nylon 6 and comprising a core wire coated with a nylon 6 thermoplastic coating low molecular weight, at a temperature of 50 to 90 °c is a suitable temperature that may vary somewhat with respect to the indicated value according to the treatment time and the voltage used during this treatment.

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For fixing¹ nodes, proper temperature of 125 to 135 °c is then also depending on the duration I £voltage.

The heat treatments can be performed in a manner connae using infrared radiation, steam, hot-toto àir, liquids^; boiling or high frequency radio waves..

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