JP5296721B2 - Synthetic net - Google Patents

Description

  The present invention relates to a synthetic fiber net that is required to maintain strength in a state exposed to ultraviolet rays, such as a rock fall prevention net.

  In order to prevent the fall of stones and earth and sand on the slopes of mountainous areas and forest belts, a rockfall prevention net is laid. From the standpoint of strength, this net for rockfall prevention is mainly made of a wire netting as a net having high weather resistance and strength. However, since the wire mesh is heavy, it takes labor to raise the slope, and it cannot be laid on unstable ground. Furthermore, since the rigidity is high, workability is poor, and it is difficult to adapt to the shape of the ground, stones, etc., so that stress is easily concentrated on the portion that is in contact with these locally and easily breaks. In addition, there is a drawback that the tip of the rusted and broken net is dangerous. Resin-coated wire nets in which metal strands are coated with resin have been developed to compensate for the rust-related drawbacks, but this is disadvantageous in terms of cost because it requires special equipment for production. In addition, nets with high weather resistance and strength using metal wires are on the market, but the material cost is high, and it is necessary to attach a binding tool to all the crossing parts of the wires in order to make a mesh. There is a drawback that it takes time and effort.

  A light synthetic fiber net is used in place of a wire net for slopes where strength is not so high. However, synthetic fiber nets must cope with deterioration caused by ultraviolet rays contained in sunlight. For example, in Patent Document 1, copper compound and carbon black or titanium black are finely dispersed in polyamide fibers to prevent oxidation and absorb ultraviolet rays. A net with an effect is described.

  On the other hand, Patent Document 2 discloses a polyethylene single yarn fiber whose strength is improved by devising the structure of molecular bonds. This fiber is strong and has strength exceeding that of a steel wire mesh. However, since such a fiber is affected by the molecular structure itself when an additive is added, the original strength cannot be maintained when an additive for enhancing weather resistance is added. In recent years, nets made of synthetic fibers coated with resin have also been put on the market as synthetic fiber nets with improved weather resistance without using additives, but this is disadvantageous in terms of cost because it requires special equipment for production. It has become.

JP-A-9-78417 Japanese Patent Publication No. 64-8732

  The present invention has been made in view of such a situation, and an object of the present invention is to obtain a synthetic fiber net having lightness and excellent workability while having weather resistance while having strength comparable to a wire net.

  In order to achieve the above-mentioned object, the present invention extrudes a low-concentration resin solution from a spinneret, cools the obtained filament below the swelling point of the polymer in the solvent, and further heats it to the temperature of the polymer melting point. The high-strength synthetic fiber obtained by stretching is twisted, while the weather-resistant synthetic fiber is twisted by twisting the weather-resistant synthetic fiber that has been heated and melted and extruded from the spinneret and stretched. A synthetic fiber twisted yarn is covered in a spiral shape.

  The high-strength synthetic fiber thus obtained has a strong tensile strength with almost no extension because the chain macromolecules are oriented in the length direction. On the other hand, the weather-resistant synthetic fiber has a large amount of side chains, so even if it is exposed to ultraviolet rays, its energy is consumed exclusively for the decomposition of the side chains, and thus it is difficult to affect the chain molecules. Synthetic fiber nets that use mesh yarn that spirally surrounds fibers made up of molecules with a large number of side chains are fibers that control the molecular orientation of the fiber itself and have improved weather resistance. Because it is lighter than it can be transported by manpower and can be laid on unstable ground. Furthermore, since the rigidity is low, workability is good, and it is easy to adjust to slopes and irregularities, so it is effective in reducing the impact of falling rocks. Of course, it will not rust and break. Furthermore, it does not require special equipment for production, and is superior in cost compared to a net using a material in which synthetic fibers or metal wires are covered with a resin.

It is a figure which shows the structure of the synthetic-fiber net | network of a present Example. It is the figure which measured the intensity | strength of the fiber exposed to the ultraviolet-ray.

  In FIG. 1A, a synthetic fiber net 1 extends vertically and horizontally in a state where two ropes 2 are twisted together. In the figure, the intersection c shows a state in which the mesh yarn is loosened. At each intersection c, the vertical mesh yarn 2a is added to two continuous loops c1 and c2 by twisting of the vertical mesh yarns 2c and 2d. 2b is allowed to pass through to form a knotless network. Each mesh thread 2 has a double structure of a core 3 and a sheath 4 for housing the core 3.

  FIG. 1B is an enlarged view of the structure. The core 3 is obtained by twisting many core fiber bundles 6 together. The core fiber bundle 6 is a twisted yarn of the core fiber 7. The core fiber 7 is a long fiber.

  On the other hand, the sheath 4 is composed of a large number of sheath fiber bundles 8. Each sheath fiber bundle 8 is twisted around the core 3 and the core 3 is spirally surrounded by the entire sheath fiber bundle 8 without any gaps. Each sheath fiber bundle 8 is a twisted yarn of sheath fibers 9. Similarly to the core fiber 7, the sheath fiber 9 is a long fiber.

  The core fiber 7 is made of polyethylene, has a structure in which chain macromolecules are oriented in the length direction, and has almost no side chain. Such a core fiber 7 is a gel-like filament obtained by extruding a polyethylene solution having a low concentration from the spinneret and cooling the obtained filament to a temperature below the swelling point of the polymer in the solvent through a cooling bath (water bath). Is heated to a temperature of the polymer melting point and greatly stretched. The core fiber 7 obtained in this way has a strong tensile strength with almost no extension because the chain macromolecules are oriented in the length direction. For example, “Dyneema” (trademark registration No. 4910466) manufactured by Toyobo Co., Ltd. as a fiber in which chain macromolecules are oriented in the length direction has a tensile strength of a single filament of 12 μm in diameter from 26 to It is a high-strength synthetic fiber having 36 cN / dtex, far exceeding the strength (4.4-7.9 cN / dtex) of polyethylene fibers obtained by the low-pressure method and exceeding the strength of steel per cross-sectional area.

  In general, a fiber in which such chain macromolecules are oriented in the length direction tends to be reduced in strength by ultraviolet rays. Since this has few side chains, it is considered that the energy of ultraviolet rays directly breaks the bonds of chain macromolecules and the strength decreases.

  On the other hand, the sheath fiber 9 is a fiber obtained by heating and melting polyethylene and extruding it from a spinning nozzle. Since this fiber has a larger amount of side chains than the core fiber 7 and the chain molecules are not oriented in the length direction, it is more elastic than the core fiber 7 but has a lower strength. The sheath fiber 9 has a large amount of side chains, so that it was found that even when it was exposed to ultraviolet rays, its energy was consumed exclusively for the decomposition of the side chains and hardly affected the chain molecules. . Therefore, it can be said that the sheath fiber 9 is a weather resistant synthetic fiber with respect to the core fiber 7 which is a high strength synthetic fiber.

  FIG. 2 is a diagram comparing strength retention rates of the core fiber bundle 6 and the sheath fiber bundle 8 according to the number of months of exposure. As shown in the figure, the core fiber bundle 6 rapidly loses its strength when exposed to ultraviolet rays. On the other hand, the strength reduction rate of the sheath fiber bundle 8 with many side chains is low.

  The net yarn 2 is not exposed to ultraviolet rays outdoors because the core 3 is surrounded by the sheath 4. On the other hand, the strength of the sheath 4 is lowered by ultraviolet rays, but the rate of decrease is low, and the strength surrounding the core 3 is sufficient. Further, the sheath 4 has higher elasticity than the core 3, and the core 3 that hardly extends when a pulling force is applied to the falling rock exclusively receives a load caused by falling rock or the like. Therefore, even if the strength of the sheath 4 is lowered by ultraviolet rays, the strength of the net 1 that can withstand falling rocks is not affected.

Examples are shown below.
[Falling weight impact experiment]
A drop weight impact experiment was conducted to confirm whether the synthetic fibrous net of the present invention can capture a weight having a specified weight dropped from a specified height.

"Tensile strength test"
A tensile strength test using the synthetic fibrous net of the present invention was performed. Set the distance between the grips of the constant-speed tension type tensile tester to 50 cm, cut out a test piece of 1 leg 1 leg from the net, set it on the gripper, and measured the tensile strength and elongation at a tensile speed of 15 cm / min. .

  In the above embodiment, polyethylene is used as the core fiber 7, but polyamide or polyester can be used as the fiber material in which chain macromolecules are oriented in the length direction. In the said Example, the core fiber 7 utilized the long fiber which has the length which continued the synthetic fiber net | network 1 from the end to the end. Further, although polyethylene is used as the sheath fiber 9, polyester or nylon can be used. Further, the sheath fiber 9 is a long fiber having a continuous length from the end to the end of the synthetic fiber net 1 in the same manner as the core fiber 7, but may be a short fiber. Carbon fiber may be added to the sheath fiber 9 in order to improve weather resistance. This is because the sheath fiber 9 is basically unrelated to the strength.

  The fineness and number of the core fibers 7 and the sheath fibers 9 can be used as long as they can be twisted yarns other than the above examples. Further, several to ten or more twisted yarns may be twisted to make a thicker twisted yarn. The direction and number of twists can be arbitrarily determined.

  A mesh yarn is produced by twisting the sheath fiber bundle 8 while adjusting the position so that the sheath fiber bundle 8 covers the core fiber bundle 6. For the twisting of the core fiber bundle 6 and the sheath fiber bundle 8, an existing spinning machine can be used. The coverage of the core fiber bundle 6 by the sheath fiber bundle 8 is 90 to 100%. When it is desired to increase the weather resistance, the ratio of the sheath fibers 9 is increased so as to form a thick layer. When it is desired to increase the strength, the ratio of the core fibers 7 is increased so as to form a thick layer.

  The synthetic yarn net 1 is woven by setting the mesh yarn 2 twisted by the yarn synthesizing machine to the braiding machine. If the mesh 2 is thick, it is difficult to knit a small mesh. However, the maximum mesh is not limited, and the thickness of the mesh 2 depends on the size of the object and the installation environment. It can be arbitrarily determined by, for example.

  Synthetic fiber net 1 may be subjected to resin processing for the purpose of enhancing weather resistance or antifouling, and in order to obtain an accurate mesh size for the net, heat stretching and heat shrinkage are put into the manufacturing process. be able to.

  In the above embodiment, the synthetic fiber net 1 is a knotless network, but it may be a knotted network or a knotless network. In general, a knotless network is advantageous in terms of strength. The reason is that the strength of the fiber can be directly used as the strength of the net, there is no difference in strength between the length and width, it is light, and it is not bulky when stored.

  Examples of the knotless net include a penetrating knotless net, a staggered knotless silk, a turtle shell type knotless net, a raschel net, a woven net, a twin-twisted net, and a triple-twisted net. In addition, the knotted network includes a main net, a cocoon net, and a double cocoon net.

  In order to prevent animal damage, a metal wire can be charged into the mesh thread 2. Synthetic fiber nets, which use high-strength synthetic fibers spirally covered with weather-resistant synthetic fibers, are lightweight and supple, so they have good workability during installation. Moreover, since it follows the undulations of the installation surface, it can be installed on soft ground. Since a coloring agent can be added to the sheath fiber 9, a color can be freely selected. It is also possible to easily adjust the thickness and scale of the synthetic fiber net.

1 net 2 net yarn 3 core 4 sheath 7 core fiber 9 sheath fiber

Claims (3)

  A high-strength synthetic fiber obtained by extruding a low-concentration resin solution from the spinneret, cooling the filament obtained below the swelling point of the polymer in the solvent, and heating it to the temperature of the polymer melting point is twisted. On the other hand, twisting the weather-resistant synthetic fiber that was heated and melted from polyethylene and extruded from the spinneret and stretched, and the twisted yarn of the weather-resistant synthetic fiber covered the twisted yarn of the other high-strength synthetic fiber spirally Characteristic synthetic fiber net.   2. The synthetic fiber net according to claim 1, wherein the high-strength synthetic fiber and the weather-resistant synthetic fiber are long fibers. The synthetic fiber net according to claim 1, wherein the resin constituting the high-strength synthetic fiber and the weather-resistant synthetic fiber is polyethylene.