Double rope structure

Abstract

To provide a double rope structure having excellent strength and bending resistance. [Solution] A double rope structure 10 is provided, which is composed of an inner layer 1 and an outer layer 2. In the double rope structure 10, the inner layer 1 is composed of high-strength, high-elasticity fibers having a yarn strength of 20 cN / dtex or more and a yarn elastic modulus of 400 cN / dtex or more, and the ratio of the average length of the yarns constituting the inner layer of a cut portion 1A obtained by cutting this rope structure 10 to a predetermined length, expressed as yarn length / rope length, is 1.005 or more and 1.200 or less.

Description

Related Application

[0001] This application claims the priority of Japanese Patent Application No. 2020-217505 filed on December 25, 2020, and the entire content thereof is incorporated herein by reference and made a part of this application.

Technical Field

[0002] The present invention relates to a double rope structure composed of an inner layer and an outer layer.

Background Art

[0003] A rope is formed by twisting or braiding a large number of strands into a cord or string shape, and is used in marine applications such as mooring ships and the edge ropes of fishing nets, and land applications such as towing ropes and load ropes. A strand is composed of a plurality of yarns, and a yarn is formed from a plurality of single filaments as raw yarns.

[0004] In addition to the single-layer rope structure, there is a double-layer rope structure for ropes. The double-layer rope structure is formed by arranging twisted or braided strands in the inner layer and the outer layer respectively. For example, Patent Document 1 (Utility Model Registration No. 3199266) discloses a fiber rope having a double structure of a core material and an outer layer rope covering the outside thereof, wherein the core material is made of high-strength and high-modulus fibers, and the outer layer rope is a braided rope made of yarns in which high-strength and high-modulus fibers and general-purpose fibers are mixed, and a fiber rope is disclosed in which more high-strength and high-modulus fibers are mixed than general-purpose fibers in the outer layer rope.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, while Patent Document 1 describes a rope constructed by twisting together multiple strands made of high-strength, high-modulus fibers as the core material, it does not describe the yarn that makes up the strands, and therefore does not present a technical concept of improving strength by adjusting the yarn.

[0007] Therefore, the object of the present invention is to provide a double rope structure that is excellent in strength and bending resistance. [Means for solving the problem]

[0008] The inventors of the present invention conducted diligent research to achieve the above objectives and confirmed that using high-strength, high-modulus fibers as the inner layer of a double rope structure can improve the strength of the rope structure due to the strength characteristics of the high-strength, high-modulus fibers. However, they also found that even when high-strength, high-modulus fibers are used as the inner layer, the strength of the double rope structure does not always improve. Further research revealed that by adjusting the length of the yarn constituting the high-strength, high-modulus fibers used in the inner layer to a specific ratio with respect to the length of the rope, it is possible not only to effectively utilize the inherent strength of the high-strength, high-modulus fibers but also to improve the bending resistance of the rope structure, thus completing the present invention.

[0009] In other words, the present invention may be configured in the following embodiments. [Aspect 1] A double rope structure composed of an inner layer and an outer layer, The inner layer is composed of high-strength, high-modulus fibers having a yarn strength of 20 cN / dtex or more (preferably 22 cN / dtex or more) and a yarn modulus of 400 cN / dtex or more (preferably 450 cN / dtex or more). A double rope structure in which the ratio of the average yarn length of the yarn constituting the inner layer of the cut portion to the rope length of the cut portion obtained by cutting the double rope structure to a predetermined length is 1.005 or more and 1.200 or less (preferably 1.006 to 1.180, more preferably 1.007 to 1.150, and particularly preferably 1.007 to 1.130) as yarn length / rope length. [Aspect 2] A double rope structure according to Embodiment 1, wherein the outer layer is substantially composed of non-high-strength, high-modulus fibers. [Aspect 3] A double rope structure according to embodiment 1 or 2, wherein the intersection angle of the strands constituting the inner layer with respect to the longitudinal direction of the rope is 40° or less (preferably 35° or less, more preferably 33° or less, even more preferably 30° or less, and particularly preferably 27° or less). [Aspect 4] A double rope structure according to embodiment 3, wherein the number of twists of the inner layer yarn is 150 to 0.1 T / m (preferably 100 to 2 T / m, more preferably 80 to 3 T / m, and even more preferably 60 to 6 T / m). [Aspect 5] A double rope structure according to any one of embodiments 1 to 4, wherein the yarn elongation of the high-strength, high-modulus fibers is 3 to 6% (preferably 3.5 to 5.5%). [Aspect 6] A double rope structure according to any one embodiment of embodiments 1 to 5, wherein the high-strength, high-modulus fiber is selected from at least one selected from the group consisting of liquid crystal polyester fiber, ultra-high molecular weight polyethylene fiber, aramid fiber, and poly(paraphenylenebenzobisoxazole) fiber. [Aspect 7] A double rope structure according to any one of embodiments 1 to 6, wherein the ratio of the tensile strength of the double rope structure to the yarn strength of the strands constituting the inner layer multiplied by the total number of strands in the inner layer is 40% or more (preferably 50% or more, more preferably 55% or more, and even more preferably 60% or more). [Aspect 8] A double rope structure according to any one of embodiments 1 to 7, wherein the double rope structure is subjected to a bending test in which the bending radius is 7.5 mm and the bending angle is 240°, and the strength retention rate before and after the bending test is 45% or more (preferably 50% or more, more preferably 55% or more). [Aspect 9] A double rope structure according to any one of embodiments 1 to 8, wherein the strength retention rate at 80°C is 45% or more (preferably 60% or more, more preferably 80% or more). [Aspect 10] A double rope structure according to any one of embodiments 1 to 9, wherein the inner layer and outer layer are braided structures. [Aspect 11] A double rope structure according to any one of embodiments 1 to 10, wherein the ratio of the inner layer in the double rope structure is 40% by weight or more.

[0010] Furthermore, any combination of at least two components disclosed in the claims and / or the specification and / or drawings is included in the present invention. In particular, any combination of two or more claims described in the claims is included in the present invention. [Effects of the Invention]

[0011] According to the present invention, a double rope structure is formed by using a high-strength, high-modulus fiber yarn for the inner layer, adjusting the length of the high-strength, high-modulus fiber yarn to a specific range relative to the length of the rope, and covering this inner layer with an outer layer. Therefore, it is possible to achieve both improved strength and bending resistance of the rope structure. [Brief explanation of the drawing]

[0012] This invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and the drawings are for illustrative and explanatory purposes only and should not be used to define the scope of this invention. The scope of this invention is defined by the appended claims. The drawings are not necessarily shown to scale and are exaggerated to illustrate the principles of the present invention. [Figure 1] It is a schematic exploded side view of a double-rope structure according to an embodiment of the present invention. [Figure 2] It is a schematic perspective view partially enlarging the strands forming the inner layer of the double-rope structure of FIG. 1. [Figure 3] It is a schematic perspective view for explaining the relationship between the length of one yarn among the plurality of yarns forming the strands of the cut portion of the double-rope structure and the length of the cut portion. [Figure 4] It is a schematic exploded side view of a double-rope structure according to another embodiment of the present invention. [Figure 5] It is a schematic side view for explaining the twist abrasion test.

Mode for Carrying Out the Invention

[0013] Hereinafter, the present invention will be described in detail based on examples. FIG. 1 is a schematic exploded side view of a double-rope structure according to an embodiment of the present invention, and FIG. 2 is a schematic perspective view partially enlarging the strand 3 forming the inner layer of the double-rope structure of FIG. 1. As shown in FIG. 1, the double-rope structure 10 includes an inner layer 1 and an outer layer 2 covering this inner layer, and in FIG. 1, the illustration of the outer layer 2 is partially omitted to show the state of the inner layer 1.

[0014] Both the inner layer 1 and the outer layer 2 have a structure in which a plurality of strands are braided, each strand is composed of a plurality of yarns, and each yarn is composed of a plurality of single filaments. For example, as shown in FIG. 2, the strand 3 forming the inner layer 1 of the double-rope structure 10 in FIG. 1 is composed of a plurality of yarns 4, and each yarn 4 is a twist of a plurality of raw yarns.

[0015] Figure 1 shows a cut portion 1A in the inner layer 1 that constitutes a predetermined length V. The cut portion 1A represents the inner layer portion when the double rope structure 10 is cut to a predetermined length V. When the cut portion 1A is disassembled, multiple strands constituting the cut portion 1A are obtained, and in Figure 1, one of these strands 3A is shown as a dot. The strand 3A is composed of multiple yarns (not shown).

[0016] Figure 3 is a schematic perspective view illustrating the relationship between the length W of one yarn 4A, which is one of the multiple yarns forming the strand 3A of the cut portion 1A, and the length V of the cut portion 1A. When the double rope structure 10 is cut at a predetermined length V, the strand 3A present in the cut portion 1A is disassembled into yarn 4A, and the length of yarn 4A is measured, it is found that yarn 4A has a length W.

[0017] In the double rope structure of the present invention, the high-strength, high-modulus fibers constituting the inner layer 1 improve both the strength and bending resistance of the double rope structure. Therefore, at the cut portion 1A, the length W of the yarn 4A forming the strand 3A is in the range of 1.005 to 1.200 as yarn length / rope length (W / V).

[0018] In forming the inner layer 1 of the double rope structure 10, the length of the yarn constituting the strands is made close to the length of the rope itself, thereby efficiently utilizing the strength of yarn made from high-strength, high-modulus fibers. On the other hand, if the length of the yarn constituting the strands is too close to the length of the rope itself, it becomes difficult not only to form the strands into a twisted or braided body, but the shape of the double rope structure becomes unstable, making it difficult to improve its bending resistance.

[0019] Furthermore, it is preferable that the intersection angle of the strands is as small as possible with respect to the longitudinal direction Z (hereinafter simply referred to as the rope longitudinal direction Z) passing through the center of the double rope structure. For example, as shown in Figure 1, the strands 3A constituting the inner layer intersect the rope longitudinal direction Z at an intersection angle θ (0° < θ < 90°). The intersection angle θ can be measured using an image taken of the side of the fibers with the outer layer 1 removed and the inner layer 2 exposed. For example, in Figure 1, strands 3A intersecting the rope longitudinal direction Z of the double rope structure 10 are randomly selected, and the angle θ formed between the rope longitudinal direction Z and the side of the strand 3A on the rope longitudinal direction Z side is defined as the intersection angle.

[0020] Figure 4 is a schematic exploded side view of a double rope structure according to another embodiment of the present invention. The double rope structure 20 comprises an inner layer 6 and an outer layer 2 covering the inner layer. The outer layer 2 is a braided body and integrates with the inner layer 6 to form the double rope structure. Parts common to Figure 1 are described using the same reference numerals and their explanations are omitted.

[0021] The inner layer 6 has a twisted structure formed by twisting together multiple strands 7, each strand consisting of multiple yarns, and each yarn consisting of multiple single threads. For example, the strands 7 forming the inner layer 6 of the double rope structure 20 in Figure 4 are composed of multiple yarns 4, similar to the strands 3 shown in Figure 2, and each yarn 4 is a twisted body of multiple raw threads.

[0022] Figure 4 shows a cut portion 6A in the inner layer 6 that constitutes a predetermined length V. The cut portion 6A represents the inner layer portion when the double rope structure 20 is cut to a predetermined length V. When the cut portion 6A is decomposed, multiple strands constituting the cut portion 6A are obtained, and in Figure 4, one of these strands 7A is shown as a dot. The strand 7A is composed of multiple yarns (not shown), and the length W of the yarns forming the strand 7A is in the range of yarn length / rope length (W / V) of 1.005 to 1.200 with respect to the length V of the cut portion 6A.

[0023] Furthermore, as shown in Figure 4, the strands 7A constituting the inner layer intersect the longitudinal direction Z of the rope at an intersection angle θ (0° < θ < 90°). For example, in Figure 4, strands 7A intersecting the longitudinal direction Z of the rope passing through the center of the double rope structure 20 are randomly selected, and the angle θ formed between the longitudinal direction Z of the rope and the side of the strand 7A on the longitudinal direction Z side is defined as the intersection angle.

[0024] As shown in Figures 1 and 4, the outer layer 2 is formed from a braided strand. Each strand is further composed of multiple yarns, as shown in Figure 2.

[0025] Preferred embodiments of the double rope structure of the present invention will be described below. (Inner layer) In the inner layer constituting the double rope structure of the present invention, the ratio of the average yarn length of the yarn constituting the inner layer of a cut portion to the rope length of a cut portion of 1 m (more precisely, 1.000 m) is in the range of 1.005 to 1.200, preferably 1.006 to 1.180, more preferably 1.007 to 1.150, and particularly preferably 1.007 to 1.130. The yarn length and rope length are values ​​measured by the method described in the embodiments described later. Within this range, the tensile strength of the double rope structure can be improved, and a high strength retention rate can be maintained even after bending.

[0026] The inner layer of the double rope structure of the present invention may be a twisted body or a braided body, as long as the yarn length / rope length (W / V) is within a predetermined range. In the case of a twisted body, it is often 3-strand or 4-strand, and the braided body may be 8-strand, 12-strand, 16-strand, 32-strand, etc. Of these, the braided body is preferred, and in particular, 8-strand, 12-strand, and 16-strand braided bodies are preferred, with 12-strand and 16-strand braided bodies being more preferred. Furthermore, the braided body may be round-braided or square-braided, but from the viewpoint of excellent abrasion resistance, it is preferred to be round-braided.

[0027] When twisting or braiding, the pitch (stitches / inch) may be adjusted to, for example, 2.5 to 20, preferably 3 to 18, and more preferably 3.3 to 15. The pitch represents the number of yarns per inch in the longitudinal direction of the rope and can be measured and confirmed, for example, using a Keyence Corporation VHX-2000 digital microscope.

[0028] Furthermore, when twisting or braiding, the lead (mm / mesh) may be adjusted to, for example, 18 to 100, preferably 20 to 90, and more preferably 23 to 85. Here, the lead represents the length required for the strand to wrap around the rope once.

[0029] Furthermore, when twisting or braiding, the lead / diameter ( / mesh) ratio may be adjusted to, for example, 8 to 70, preferably 9 to 60, and more preferably 10 to 50. Here, lead / diameter represents the ratio of the lead to the diameter of the inner layer.

[0030] It is preferable that the intersection angle of the strands with respect to the longitudinal direction of the rope be as small as possible, and θ may be 40° or less. The intersection angle θ of the strands constituting the layer with respect to the longitudinal direction of the rope is preferably 35° or less, more preferably 33° or less, even more preferably 30° or less, and particularly preferably 27° or less. The lower limit of the intersection angle may be, for example, 2° or more, preferably 3° or more, and more preferably 6° or more.

[0031] For the multiple yarns constituting the strand, the number of twists in each yarn may be 150 to 0.1 T / m, preferably 100 to 2 T / m, more preferably 80 to 3 T / m, even more preferably 70 to 5 T / m, and particularly preferably 60 to 6 T / m. A smaller number of twists can improve the strength of the rope, but no twist reduces the ease of handling when forming the strand. Note that 0.1 T / m is synonymous with 1 T / 10m. Furthermore, for the multiple strands constituting the inner layer, twists may be applied as needed within the range that satisfies the specific yarn length / rope length defined in this invention. In addition, multiple strands may be further twisted together as needed within the range that satisfies the specific yarn length / rope length defined in this invention.

[0032] The yarn fineness can be appropriately set according to the required fineness for the double rope structure, for example, it may be 30 dtex or more, preferably 200 dtex or more, and more preferably 400 dtex or more. Alternatively, the yarn fineness may be 6000 dtex or less, preferably 5000 dtex or less, more preferably 4000 dtex or less, and even more preferably 2500 dtex or less.

[0033] The diameter of the inner layer can be set appropriately depending on the application, but may be, for example, 0.5 to 100 mm, preferably 1.5 to 80 mm, and more preferably 2 to 60 mm. The diameter of the inner layer can be measured using an electronic caliper by cutting the fiber cross section in a direction perpendicular to the longitudinal direction of the rope after the double rope structure has been embedded in resin.

[0034] The ratio of the inner layer in a double rope structure may be, for example, 40% to 90% by weight, preferably 50% to 80% by weight, and more preferably 60% to 75% by weight, from the viewpoint of utilizing the strength of high-strength, high-modulus fibers.

[0035] The high-strength, high-modulus fibers constituting the inner layer are not particularly limited as long as they are high-strength, high-modulus fibers capable of achieving a yarn strength of 20 cN / dtex or more and a yarn modulus of 400 cN / dtex or more. Specific examples include, for instance, liquid crystal polyester fibers (Vectran™, Siberas™, Zexion™, etc.), ultra-high molecular weight polyethylene fibers (Izanas™, Dyneema™, etc.), aramid fibers (Kevlar™, Twaron™, Technora™, etc.), and poly(paraphenylenebenzobisoxazole) fibers (Zylon™, etc.). Of these, liquid crystal polyester fibers or ultra-high molecular weight polyethylene fibers are preferred from the viewpoint of excellent abrasion resistance, liquid crystal polyester fibers or aramid fibers are preferred from the viewpoint of heat resistance, and liquid crystal polyester fibers are preferred from the viewpoint of excellent heat resistance and abrasion resistance.

[0036] Liquid crystal polyester fibers can be manufactured, for example, by melt-spinning liquid crystal polyester and then solid-phase polymerization of the spun yarn. Liquid crystal polyester multifilaments are fibers made up of two or more liquid crystal polyester monofilaments. Liquid crystal polyester is a polyester that exhibits optical anisotropy (liquid crystallinity) in the molten phase, and can be identified, for example, by placing a sample on a hot stage, heating it under a nitrogen atmosphere, and observing the transmitted light of the sample with a polarizing microscope. Furthermore, liquid crystal polyester consists of repeating structural units derived from, for example, aromatic diols, aromatic dicarboxylic acids, or aromatic hydroxycarboxylic acids, and the chemical composition of these structural units is not particularly limited as long as it does not impair the effects of the present invention. Moreover, liquid crystal polyester may also contain structural units derived from aromatic diamines, aromatic hydroxyamines, or aromatic aminocarboxylic acids, to the extent that it does not hinder the effects of the present invention.

[0037] For example, preferred structural units are shown in Table 1. [Table 1] Here, Y exists in a number ranging from 1 to the maximum number of substitutions possible in the aromatic ring, and each is independently selected from the group consisting of hydrogen atoms, halogen atoms (e.g., fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc.), alkyl groups (e.g., alkyl groups with 1 to 4 carbon atoms such as methyl groups, ethyl groups, isopropyl groups, t-butyl groups, etc.), alkoxy groups (e.g., methoxy groups, ethoxy groups, isopropoxy groups, n-butoxy groups, etc.), aryl groups (e.g., phenyl groups, naphthyl groups, etc.), aralkyl groups [benzyl groups (phenylmethyl groups), phenethyl groups (phenylethyl groups), etc.], aryloxy groups (e.g., phenoxy groups, etc.), and aralkyloxy groups (e.g., benzyloxy groups, etc.).

[0038] More preferred structural units include those shown in Examples (1) to (18) in Tables 2, 3, and 4 below. If a structural unit in a formula can exhibit multiple structures, two or more such structural units may be combined and used as structural units to constitute the polymer.

[0039] [Table 2]

[0040] [Table 3]

[0041] [Table 4]

[0042] In the constituent units of Tables 2, 3, and 4, n is an integer of 1 or 2, and each constituent unit n=1 and n=2 may exist alone or in combination; Y1 and Y2 may independently be a hydrogen atom, a halogen atom (e.g., fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), an alkyl group (e.g., a C1-C4 alkyl group such as a methyl group, ethyl group, isopropyl group, t-butyl group, etc.), an alkoxy group (e.g., a methoxy group, ethoxy group, isopropoxy group, n-butoxy group, etc.), an aryl group (e.g., a phenyl group, naphthyl group, etc.), an aralkyl group [benzyl group (phenylmethyl group), phenethyl group (phenylethyl group), etc.], an aryloxy group (e.g., a phenoxy group, etc.), an aralkyloxy group (e.g., a benzyloxy group, etc.). Among these, preferred Ys include hydrogen atoms, chlorine atoms, bromine atoms, or methyl groups.

[0043] Furthermore, Z can be represented by the substituent shown in the following formula. [ka]

[0044] A preferred liquid crystalline polyester preferably has two or more naphthalene skeletons as constituent units. Particularly preferably, the liquid crystalline polyester contains both constituent units (A) derived from hydroxybenzoic acid and constituent units (B) derived from hydroxynaphthoic acid. For example, constituent unit (A) may be the following formula (A), and constituent unit (B) may be the following formula (B). From the viewpoint of easily improving melt moldability, the ratio of constituent units (A) to constituent units (B) may be preferably in the range of 9 / 1 to 1 / 1, more preferably 7 / 1 to 1 / 1, and even more preferably 5 / 1 to 1 / 1.

[0045] [ka] [ka]

[0046] Furthermore, the sum of the constituent units of (A) and (B) may be, for example, 65 mol% or more, more preferably 70 mol% or more, and even more preferably 80 mol% or more, relative to the total constituent units. Liquid crystal polyesters in which the constituent units of (B) in particular constitute 4 to 45 mol% of the polymer are preferred.

[0047] The melting point of the liquid crystal polyester preferably used in this invention is 250 to 360°C, more preferably 260 to 320°C. Here, the melting point is the main absorption peak temperature observed when measured with a differential scanning calorimeter (DSC; Mettler TA3000) in accordance with the JIS K7121 test method. Specifically, 10 to 20 mg of the sample is placed in an aluminum pan and then nitrogen is passed through it as a carrier gas at 100 cc / min. The endothermic peak is measured when the temperature is raised at 20°C / min. If a clear peak does not appear in the first run of the DSC measurement depending on the type of polymer, the temperature should be raised to 50°C higher than the expected flow temperature at a heating rate of 50°C / min, held at that temperature for 3 minutes to completely melt, then cooled to 50°C at a cooling rate of -80°C / min, and then the endothermic peak is measured at a heating rate of 20°C / min.

[0048] Furthermore, thermoplastic polymers such as polyethylene terephthalate, modified polyethylene terephthalate, polyolefin, polycarbonate, polyamide, polyphenylene sulfide, polyether ether ketone, and fluororesin may be added to the liquid crystal polyester, to the extent that the effects of the present invention are not impaired. In addition, various additives such as inorganic substances such as titanium dioxide, kaolin, silica, and barium oxide, colorants such as carbon black, dyes, and pigments, antioxidants, ultraviolet absorbers, and light stabilizers may be added.

[0049] The yarn strength of the high-strength, high-modulus fiber is 20 cN / dtex or higher, preferably 22 cN / dtex or higher. There is no particular upper limit, but for example, it may be 40 cN / dtex. Furthermore, the yarn modulus of the high-strength, high-modulus fiber is 400 cN / dtex or higher, preferably 450 cN / dtex or higher. There is no particular upper limit, but for example, it may be 600 cN / dtex. Furthermore, the yarn elongation of the high-strength, high-modulus fiber may be, for example, 3 to 6%, and preferably 3.5 to 5.5%. Yarn strength, yarn modulus, and yarn elongation are values ​​measured by the methods described in the examples below.

[0050] (outer layer) In the double rope structure of the present invention, the outer layer is composed of a wrapped or braided body of strands that cover the inner layer. The wrapped body can be formed by spirally winding strands around the inner layer, and the braided body can be formed by braiding the inner layer with the inner layer as the core using 8-strand, 12-strand, 16-strand, 24-strand, 32-strand, 40-strand, 48-strand, 64-strand, etc. Of these, braided bodies of 16-strand, 24-strand, 32-strand, 40-strand, and 48-strand are preferred, and braided bodies of 24-strand, 32-strand, or 40-strand are more preferred.

[0051] The strands constituting the outer layer may be formed from the high-strength, high-modulus fibers, or from non-high-strength, non-high-modulus fibers (hereinafter simply referred to as non-high-strength, high-modulus fibers). In the case of non-high-strength, high-modulus fibers, for example, the yarn strength may be less than 20 cN / dtex, and is usually around 1 cN / dtex to 15 cN / dtex. The yarn modulus may be less than 400 cN / dtex, and is usually around 10 cN / dtex to 200 cN / dtex. The yarn elongation may be, for example, 3 to 20%, preferably 7 to 20%. Examples of non-high-strength, high-modulus fibers include general-purpose synthetic fibers such as general-purpose polyester fibers (e.g., polyethylene terephthalate fibers), polyolefin fibers (e.g., polyethylene fibers, polypropylene fibers), polyamide fibers (e.g., nylon 6 fibers, nylon 6,6 fibers), and polyvinyl alcohol fibers (e.g., Vinylon®).

[0052] In a double rope structure, the strength of the rope structure can be ensured by the inner layer, so the outer layer may be substantially composed of non-high-strength, high-modulus fibers. Here, "substantially" means that the proportion of non-high-strength, high-modulus fibers in the outer layer is 80% by weight or more, and preferably 90% by weight or more (90-100% by weight).

[0053] The fineness of the yarn forming the outer strand can be appropriately set according to the fineness required for the double rope structure, for example, it may be 50 to 1000 dtex, preferably 100 to 500 dtex, and more preferably 200 to 400 dtex.

[0054] (Double rope structure) The double rope structure of the present invention is a double rope structure composed of an inner layer and an outer layer, and has a specific inner layer structure, thereby improving both strength and bending resistance.

[0055] For example, in a double rope structure, since higher strength can be achieved in the inner layer, the tensile strength may exceed, for example, 2.0 kN, preferably 2.2 kN or more, more preferably 2.4 kN or more, and even more preferably 3.0 kN or more. There is no particular upper limit, but for example, it may be 6.0 kN. The tensile strength of the double rope structure is a value measured by the method described in the embodiments below.

[0056] The strength utilization rate of the double rope structure is preferable as it is higher, but may be, for example, 40% or more, preferably 50% or more, more preferably 55% or more, and even more preferably 60% or more. There is no particular upper limit, but may be, for example, 100%. The strength utilization rate of the double rope structure is calculated by expressing the ratio of the tensile strength of the double rope structure to the yarn strength of the yarn constituting the inner layer multiplied by the total number of strands in the inner layer as a percentage.

[0057] Furthermore, the double rope structure is preferable to have a high strength retention rate before and after bending. For example, when the double rope structure is subjected to a bending test in which the bending radius is 7.5 mm and the bending angle is 240° and the bending is repeated 300,000 times, the strength retention rate before and after the bending test is preferable. For example, it may be 45% or more, preferably 50% or more, and more preferably 55% or more. There is no particular upper limit, but for example it may be 100%. The strength retention rate after bending is a value measured by the method described in the examples below.

[0058] Furthermore, the double rope structure exhibits excellent abrasion resistance. In a twisting abrasion test, a loop-shaped double rope structure is twisted three times between upper and lower pulleys with an inner diameter of 45 mm, which are spaced 500 mm apart. A load of 3 kg is applied to the lower pulley, and the pulley is moved back and forth at an angle of 180 degrees and a period of 60 cycles / minute (MV = 34.2 Hz). The number of twisting abrasion cycles until the double rope structure breaks may be, for example, 100,000 or more, preferably 200,000 or more, may exceed 550,000, more preferably 600,000 or more, even more preferably 800,000 or more, and particularly preferably 1,000,000 or more. In the test, the upper limit may be set at 277 hours (1,000,000 abrasion cycles) to judge abrasion resistance. The upper limit is not particularly limited, but may be around 5,000,000 cycles.

[0059] Furthermore, the double rope structure preferably has excellent heat resistance. The strength retention rate after being held at 80°C for 30 days, which is an indicator of heat resistance, may be, for example, 45% or more, preferably 60% or more, and more preferably 80% or more. There is no particular upper limit, but it may be, for example, 100%. The heat resistance of the double rope structure is a value measured by the method described in the examples below. [Examples]

[0060] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way by these examples. In the following examples and comparative examples, various physical properties were measured by the methods described below.

[0061] [Rope length / Inner layer yarn length] A 1,000 m section was randomly selected and cut from a double rope structure (hereinafter sometimes simply referred to as the rope structure) to obtain the rope length. The strands constituting the cut section were then disassembled to extract the inner layer, and one randomly selected strand constituting the inner layer was further disassembled to obtain the yarn constituting the inner layer. The length of all the obtained inner layer yarns was measured while they were taut according to JIS L 1013, and the average value was taken as the yarn length.

[0062] [Yarn fineness (dtex)] The strands constituting the rope structure were disassembled to obtain the yarns that make up the inner and outer layers, and the yarn fineness of the obtained yarns was measured according to JIS L 1013.

[0063] [Yarn strength (N), Yarn strength (cN / dtex), Yarn elongation (%), Yarn modulus of elasticity] The strands constituting the rope structure were disassembled to obtain the yarns that make up the inner layer. The tensile strength of the obtained yarns was measured as yarn strength (N) according to JIS L 1013, and the yarn elongation and yarn modulus were also measured. Furthermore, the yarn strength (cN / dtex) was defined as the value obtained by dividing the yarn strength (cN) by the yarn fineness (dtex).

[0064] [Pitch (eyes / inch) · Lead (mm / eyes)] The pitch was determined by measuring the number of yarns per inch in the rope using a Keyence VHX-2000 digital microscope. The lead, which is the length of strand required to complete one rotation of the rope, was calculated as 25.4 / (pitch) × (number of strands).

[0065] [diameter] The diameters of the double rope structure and the inner layer were measured using electronic calipers.

[0066] [Intersection angle] Using a Keyence VHX-2000 digital microscope, the angle between the strands in the inner layer of a double-rope structure and the longitudinal direction of the rope was measured.

[0067] [Number of twists in yarn] The unraveled yarn was measured with a measuring tape to determine its twist.

[0068] [Tensile strength of rope (kN) and strength utilization rate (%)] For the double rope structure, a spiral-type rope evaluation jig (manufactured by Chubu Machine Co., Ltd.) was used as the gripping fixture for the universal testing machine. The rope was wrapped around the groove of the spiral section, and the rope was fixed by the frictional resistance of the surface. The tensile strength of the double rope structure was then measured in accordance with JIS L 1013. Furthermore, the strength utilization rate of the double rope structure was calculated by multiplying the yarn strength of the strands constituting the inner layer by the total number of strands in the inner layer to determine the maximum strength, and then expressing the result as a percentage.

[0069] [Flexural resistance: Strength retention rate after bending (%)] A bending test was conducted using a bending test machine (TC111L / Yuasa Systems) with a tension-free bending test fixture (DX-TFB / Yuasa Systems Equipment Co., Ltd.), with a bending radius of 7.5 mm and a bending angle of 240°, repeating the bending 300,000 times. The tensile strength of the double rope structure was measured before and after the bending test. The retention rate after bending was calculated as the tensile strength of the double rope structure after the bending test relative to the tensile strength of the double rope structure before the bending test, and expressed as a percentage.

[0070] [Abrasion resistance: Twisted abrasion] As shown in Figure 5, for the twisting abrasion test, a sample of the double rope structure was placed on the upper and lower pulleys and secured to prevent slippage between the pulleys and the double rope structure. The inner diameter of both the upper and lower pulleys was 45 mm, and the distance between the centers of the upper and lower pulleys was adjusted to 500 mm when the double rope structure was secured. The double rope structure was first formed into a loop, and then the looped double rope structure was twisted three times to form a twisted section X of approximately 20 mm. This structure was then fixed to the upper and lower pulleys, and a load of 3 kg was applied to the lower pulley in the direction indicated by the downward arrow. The pulley was moved back and forth at an angle of 180 degrees and a period of 60 cycles / minute (MV = 34.2 Hz), and the number of cycles of the pulley until the inner layer broke was counted when the twisted section of the double rope structure was worn down. The upper limit of the number of cycles was set at 1 million.

[0071] [Heat resistance] The double rope structure was first stored in a constant temperature chamber at 80°C for 30 days. After that, it was removed to a test room under standard conditions (temperature: 20±2°C, relative humidity: 65±2%) and its tensile strength was measured within 30 minutes. For heat resistance, the tensile strength of the double rope structure after the heating test was calculated as a percentage of the tensile strength of the double rope structure before the heating test.

[0072] [Example 1] Using liquid crystal polyester multifilament (Vectran, manufactured by Kuraray Co., Ltd., fineness 1760 dtex) as a high-strength, high-modulus fiber, an inner layer rope was manufactured on an EL-type 12-braid braiding machine (manufactured by Kokubun Limited Co., Ltd.) by adjusting the blader's rotation speed and draw speed so that the pitch was 13 stitches / inch. Using the obtained inner layer rope as the core material, polyester multifilament (manufactured by Toray Industries, Inc., fineness 280 dtex, yarn strength 7.2 cN / dtex, yarn modulus of elasticity 88 cN / dtex, yarn elongation 15.1%) was used to manufacture a double rope on a medium-sized 32-braid braiding machine (manufactured by Kokubun Limited Co., Ltd.) by adjusting the blader's rotation speed and draw speed so that the pitch was 46 stitches / inch.

[0073] [Examples 2-4] A double rope structure was manufactured in the same manner as in Example 1, except that the pitch and lead / diameter of the inner layer of the double rope structure were changed as shown in Table 5. The results are shown in Table 5.

[0074] [Example 5] A double rope structure was manufactured in the same manner as in Example 1, except that the high-strength, high-modulus fiber for the inner layer of the double rope structure was changed to ultra-high molecular weight polyethylene multifilament (Toyobo Co., Ltd., "Izanas", fineness 1750 dtex). The results are shown in Table 5.

[0075] [Example 6] A double rope structure was manufactured in the same manner as in Example 5, except that the pitch and lead / diameter of the inner layer of the double rope structure were changed as shown in Table 5. The results are shown in Table 5.

[0076] [Example 7] A double rope structure was manufactured in the same manner as in Example 1, except that the high-strength, high-modulus fiber for the inner layer of the double rope structure was changed to p-aramid multifilament (Teijin Aramid, "Technora", fineness 1700 dtex). The results are shown in Table 5.

[0077] [Example 8] A double rope structure was manufactured in the same manner as in Example 7, except that the pitch and lead / diameter of the inner layer of the double rope structure were changed as shown in Table 5. The results are shown in Table 5.

[0078] [Example 9] Using liquid crystal polyester multifilament (Vectran, manufactured by Kuraray Co., Ltd., fineness 1760 dtex) as a high-strength, high-modulus fiber, an inner layer rope was manufactured on a large 8-braid braiding machine (manufactured by Kokubun Limited Co., Ltd.) by adjusting the blader's rotation speed and draw speed so that the pitch was 9 stitches / inch. Using the obtained inner layer rope as the core material, polyester multifilament (manufactured by Toray Industries, Inc., fineness 167 dtex, yarn strength 7.2 cN / dtex, yarn modulus of elasticity 88 cN / dtex, yarn elongation 15.1%) was used to manufacture a double rope on a medium-sized 32-braid braiding machine (manufactured by Kokubun Limited Co., Ltd.) by adjusting the blader's rotation speed and draw speed so that the pitch was 46 stitches / inch.

[0079] [Example 10] Using liquid crystal polyester multifilament (Vectran, manufactured by Kuraray Co., Ltd., fineness 5280 dtex) as a high-strength, high-modulus fiber, an inner layer rope was manufactured on an EL-type 12-braid braiding machine (manufactured by Kokubun Limited Co., Ltd.) by adjusting the blader's rotation speed and draw speed so that the pitch was 9 stitches / inch. Using the obtained inner layer rope as the core material, a double rope was manufactured on a medium-sized 54-braid braiding machine (manufactured by Kokubun Limited Co., Ltd.) by adjusting the blader's rotation speed and draw speed so that the pitch was 30 stitches / inch, using polyester multifilament (manufactured by Toray Industries, Inc., fineness 244 dtex, yarn strength 7.2 cN / dtex, yarn modulus 88 cN / dtex, yarn elongation 15.1%).

[0080] [Comparative Examples 1-2] A double rope structure was manufactured in the same manner as in Example 1, except that the pitch and lead / diameter of the inner layer of the double rope structure were changed as shown in Table 5. The results are shown in Table 5.

[0081] [Comparative Example 3] A double rope structure was manufactured in the same manner as in Example 1, except that the number of yarn twists and pitch of the inner layer of the double rope structure were changed as shown in Table 5. The results are shown in Table 5.

[0082] [Comparative Example 4] A double rope structure was manufactured in the same manner as in Example 2, except that the inner rope of the double rope structure was changed to polyester multifilament (manufactured by Toray Industries, Inc., fineness 1670 dtex, yarn strength 7.2 cN / dtex, yarn modulus of elasticity 88 cN / dtex, yarn elongation 15.1%) as the core material. The results are shown in Table 5.

[0083] [Table 5]

[0084] As shown in Table 5, in Comparative Example 1, the yarn length / rope length ratio is too large. Therefore, despite forming the inner layer with high-strength, high-modulus fibers, the strength of the high-strength, high-modulus fibers cannot be effectively utilized, resulting in a reduction in the tensile strength and strength utilization rate of the double rope structure. Furthermore, in Comparative Example 2, the yarn length / rope length ratio is small, so the strength retention rate after bending is not sufficiently maintained. Furthermore, in Comparative Example 3, the strength cannot be effectively utilized because high-strength, high-modulus fibers are twisted into highly twisted yarn. Therefore, even if the fibers used and the number of pitches are appropriate, the tensile strength of the double rope structure is insufficient. In Comparative Example 4, the tensile strength of the double rope structure is insufficient because the yarn strength and yarn modulus are too low.

[0085] On the other hand, Examples 1 to 10 all exhibited higher tensile strength and strength utilization rates of the double rope structure than Comparative Example 1, and higher strength retention rates after bending than Comparative Example 2. In particular, the double rope structures of Examples 1-6 and 9-10 exhibit excellent resistance to twisting abrasion, while the double rope structures of Examples 1-4 and 7-10 exhibit excellent heat resistance. [Industrial applicability]

[0086] The double rope structure of the present invention can be very preferably used in aquatic applications such as mooring ships, edging for fishing nets, mooring floating watercraft installed on the water, and ropes for mooring floating offshore structures used in marine resource exploration to the seabed; onshore applications such as towing ropes, cargo ropes, wind power generation equipment, and substations; and also in fields such as sports and leisure.

[0087] As described above with reference to the drawings, preferred embodiments of the present invention have been explained. However, those skilled in the art will be able to make various additions, modifications, or deletions without departing from the spirit of the present invention by reviewing this specification, and such additions, modifications, or deletions will also be included within the scope of the present invention.

Claims

[Claim 1] A double rope structure consisting of an inner layer and an outer layer, The inner layer is made of high-strength, high-elasticity fibers having a yarn strength of 20 cN / dtex or more and a yarn elastic modulus of 400 cN / dtex or more, A double rope structure, in which the ratio of the average value of the yarn length of the yarn constituting the inner layer of the cut portion to the rope length of the cut portion obtained by cutting the double rope structure at a predetermined length is 1.005 or more and 1.200 or less, in terms of yarn length / rope length.

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