Carbon fiber rope, infrastructure material using carbon fiber rope, electric wire cable, and power transmission facility

Abstract

Provided is a carbon fiber rope in which three or more strands are twisted or combined and the strands satisfy (i) to (iii) in order to achieve both strength and workability. (i) The strands each include a bundle of carbon fibers. (ii) The drape value of each strand is 2-24 cm. (iii) When one end of each strand is fixed and the other end thereof is a free end that can be rotated around the axis of the strand, the remaining twist angle is 1.5°-7.5°.

Description

Carbon fiber ropes, infrastructure materials using carbon fiber ropes, power cables and transmission equipment

[0001] This invention relates to carbon fiber rope, infrastructure materials using the carbon fiber rope, electric wire cables, and power transmission equipment.

[0002] Traditionally, industrial ropes have used synthetic fibers such as polyester and nylon, and in recent years, the use of high-strength ropes made from aramid fibers and ultra-high molecular weight polyethylene fibers to replace metal wire ropes has been considered. However, from the perspective of elastic modulus, it is difficult to replace metal wire ropes with synthetic fibers, and metal wire ropes are still widely used in infrastructure applications where high elastic modulus is important. However, metal wire ropes have a low specific modulus of elasticity and are heavy, so there is a great need to replace them with other materials that have a higher specific modulus of elasticity.

[0003] Carbon fiber exists as a fiber that exhibits an elastic modulus equal to or greater than that of metal wire rope, but its use as a rope has not been widely considered. Normally, carbon fiber is used as a composite material after resin impregnation and curing, but since the elastic modulus decreases due to the resin content, it is necessary to use carbon fiber with a high elastic modulus to exhibit an elastic modulus equivalent to that of metal wire rope. For example, Patent Document 1 discloses technology related to carbon fiber with high elastic modulus and strength. Patent Document 2 discloses a technology that makes a composite material having a core wire that is twisted and bound with a restraining material and then solidified with a hardening agent, making it less likely to break when subjected to bending stress and bringing its handling closer to that of metal wire. Furthermore, Patent Document 3 discloses a technology that achieves both strength and lightness greater than that of metal wire by creating a linear structure in which a carbon fiber bundle is twisted, covered with a covering thread, and then the outer circumference is covered with an elastomer.

[0004] International Publication No. 2019 / 244830, International Publication No. 2014 / 196432, Japanese Patent Publication No. 2023-70242

[0005] However, in Patent Document 1, while composite materials can exhibit elastic modulus equivalent to that of metal wire ropes when impregnated and cured with resin using a general method, the problem was that the less flexible composite material differed significantly in handling from that of metal wire ropes. Furthermore, in Patent Document 2, while it was possible to increase strength and flexibility in the bending direction by twisting carbon fiber bundles and solidifying them with a hardening agent, there were limitations to the range of bending due to the solidification, and problems included a decrease in specific modulus due to the resin content, and increased costs due to the complicated manufacturing process and low productivity. In Patent Document 3, it was found that because carbon fiber bundles that were originally untwisted were twisted afterward, slack occurred in the single fibers within the carbon fiber bundle, reducing stress transmission between single fibers within the carbon fiber bundle, making it difficult to improve tensile strength without resin impregnation.

[0006] Therefore, the present invention aims to provide a carbon fiber rope that achieves both strength and ease of installation, infrastructure materials using the carbon fiber rope, electric wires and cables, and power transmission equipment.

[0007] As a result of diligent research, the inventors of the present invention have found that the above problem can be solved by keeping the drape value and twist angle of the strands contained in the rope within a certain range, and have completed the present invention described below.

[0008] In other words, the present invention provides the following (1) to (10): (1) A carbon fiber rope having three or more strands twisted or combined, wherein the strands satisfy (i) to (iii): (i) The strands contain a bundle of carbon fibers. (ii) The drape value of the strands is 2 cm or more and 24 cm or less. (iii) When one end of the strands is a fixed end and the other end is a free end that can rotate with respect to the axis of the strands, the remaining twist angle is 1.5° or more and 7.5° or less. (2) The carbon fiber rope according to (1), wherein the specific modulus of elasticity RM(GPa), obtained by dividing the elastic modulus SM(GPa) of the strands by the specific gravity α(-) of the strands, satisfies formula (1). 120 ≤ RM ≤ 300 ... Equation (1) (3) A carbon fiber rope according to (1) or (2), wherein the bundle strength BS (GPA) of the carbon fiber bundles contained in the strand is 1.5 GPa or more and 10 GPa or less, and the strength ratio β(-) obtained by dividing the bundle strength BS (GPA) by the tensile strength TS (GPA) satisfies Equation (2). 0.40 ≤ β ≤ 1.00 ... Equation (2) (4) A carbon fiber rope according to any one of (1) to (3), wherein the weight percentage of carbon fibers contained in the strand is 90.0% by weight or more and 99.9% by weight or less. (5) A carbon fiber rope according to any one of (1) to (3), wherein the cross-sectional area A of the carbon fiber bundles contained in the strand is 0.2 mm ２ Above, 2.0 mm ２ The carbon fiber rope described in any one of the following items (1) to (4): (6) The carbon fiber rope described in any one of the following items (1) to (5), wherein the single filament diameter of the carbon fibers contained in the strand is 4 μm or more and less than 6 μm. (7) The carbon fiber rope described in any one of the following items (1) to (6), wherein the total length is 3000 m or more. (8) Infrastructure material using the carbon fiber rope described in any one of the following items (1) to (7). (9) Electric wire cable using the carbon fiber rope described in any one of the following items (1) to (7). (10) Power transmission equipment including the electric wire cable described in (9), wherein the distance between tower support points is 1000 m or more.

[0009] According to the present invention, it is possible to provide a carbon fiber rope that achieves both strength and ease of installation, as well as infrastructure materials, electric wires and cables, and power transmission equipment using the carbon fiber rope.

[0010] This is one example of an embodiment of the carbon fiber rope of the present invention. This is a schematic diagram showing a method for evaluating the drape value of a strand.

[0011] The embodiments for carrying out the present invention will be described below. In this specification, the term "carbon fiber" is used as a general term for carbon fiber bundles and single carbon fibers (hereinafter, single carbon fibers may also be simply referred to as "single fibers"). A carbon fiber bundle refers to a bundle of multiple single carbon fibers.

[0012] In this specification, the term "carbon fiber rope" is used as a general term for structures in which three or more strands containing carbon fibers are twisted or combined. In this specification, the term "strand" refers to a unit that constitutes a rope, and in the context of "carbon fiber rope," it is used as a general term for carbon fiber bundles and carbon fiber composite materials.

[0013] Furthermore, the upper and lower limits of the numerical ranges described below can be combined in any way. In addition, the equipment used to measure the above items is not limited to the specific equipment described in the examples below, and any equipment that can achieve equivalent accuracy may be used.

[0014] <Carbon Fiber Rope> The carbon fiber rope of the present invention is a carbon fiber rope in which three or more strands are twisted or combined, and the strands satisfy (i) to (iii). (i) The strands contain a bundle of carbon fibers. (ii) The drape value of the strands is 2 cm or more and 24 cm or less. (iii) When one end of the strands is a fixed end and the other end is a free end that can rotate with respect to the axis of the strands, the remaining twist angle is 1.5° or more and 7.5° or less.

[0015] The requirements for each aspect are described below. The carbon fiber rope of the present invention comprises three or more strands twisted or combined, and each strand contains a carbon fiber bundle. By including a carbon fiber bundle, the tensile strength and tensile modulus of the strands are improved, and the tensile strength and tensile modulus of the carbon fiber rope as a whole are also improved, enabling the rope to effectively exhibit strength even in applications requiring high rigidity.

[0016] The number of strands twisted or combined is preferably four or more, more preferably six or more, and even more preferably seven or more. There is no particular upper limit, but it is preferably 100 or less.

[0017] The rope structure should be tailored to its intended use. For example, twisted ropes such as three-strand, four-strand, six-strand, seven-strand, eight-strand, and nineteen-strand ropes, braided ropes and cords such as stone-patterned, twill-patterned, twelve-strand, and sixteen-strand braids, or ropes and strands with special structures like diamond braids can be bundled in parallel and coated with resin or covering threads. However, to maximize the high strength and high modulus of elasticity of the fibers, it is preferable to choose a rope structure with fewer twists. Depending on the application, the entire carbon fiber rope may also be coated with resin or covering threads.

[0018] The rope shown in Figure 1 is made by twisting together three strands, but this is merely one embodiment, and the present invention is not limited to this. In Figure 1, reference numeral 1 indicates the entire rope. The rope 1 uses three strands 2. Each strand 2 consists of multiple single fibers 3. In the embodiment shown in Figure 1, the strands 2 are bundles of carbon fibers, and the single fibers 3 are single carbon fibers.

[0019] While the carbon fiber bundles contained in the strands can be manufactured from known raw materials, the use of polyacrylonitrile-based carbon fiber precursor bundles is preferable from the viewpoint of mechanical property development. Polyacrylonitrile-based carbon fiber precursor bundles can be manufactured by known methods.

[0020] After flame-retardant treatment of the above-mentioned polyacrylonitrile-based carbon fiber precursor fiber bundle, a pre-carbonization treatment, a carbonization treatment, and a surface treatment can be performed to obtain the carbon fiber bundle contained in the strand used in the carbon fiber rope of the present invention. Note that each of these treatment steps may also be referred to as the flame-retardant treatment step, the pre-carbonization treatment step, the carbonization treatment step, and the surface treatment step.

[0021] In the flame-retardant process, it is preferable to heat-treat the polyacrylonitrile carbon fiber precursor fiber bundles at 200 to 300°C in an oxygen-containing atmosphere. In the pre-carbonization process, which pre-carbonizes the fiber bundles obtained in the flame-retardant process, it is preferable to heat-treat the obtained flame-retardant fiber bundles at a maximum temperature of 500 to 1,000°C in an inert atmosphere. If the maximum temperature of the pre-carbonization process is 500°C or higher, the pre-carbonized fiber bundles can be carbonized in the subsequent carbonization process without breaking due to thermal decomposition. There is no particular upper limit to the maximum temperature of the pre-carbonization process, but it is preferable to keep it below 1,000°C for functional separation from the subsequent carbonization process.

[0022] In the carbonization step of carbonizing the pre-carbonized fiber bundles, it is preferable to heat-treat the obtained pre-carbonized fiber bundles in an inert atmosphere at a maximum temperature of 1,000 to 3,000°C. From the viewpoint of increasing the elastic modulus of the resulting carbon fibers, a higher maximum temperature in the carbonization step is preferable, but from the viewpoint of maintaining the strength of the resulting carbon fibers, it is preferable to keep it below a certain temperature. For the above reasons, it is more preferable that the maximum temperature in the carbonization step be 1,200 to 2,500°C, and even more preferable that be 1,400 to 2,000°C.

[0023] In the surface treatment step for imparting oxygen functional groups to the carbon fibers obtained in the carbonization step, liquid-phase electrolytic oxidation is preferable from the viewpoint of high productivity and uniform treatment. In the present invention, there are no particular restrictions on the conditions for liquid-phase electrolytic oxidation, and it can be carried out by known methods.

[0024] Examples of electrolytes used in liquid-phase electrolytic oxidation include acidic electrolytes and alkaline electrolytes. Examples of acidic electrolytes include inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, boric acid, and carbonic acid; organic acids such as acetic acid, butyric acid, oxalic acid, acrylic acid, and maleic acid; or salts such as ammonium sulfate and ammonium bisulfate. Examples of alkaline electrolytes include aqueous solutions of hydroxides such as sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, and barium hydroxide; aqueous solutions of carbonates such as sodium carbonate, potassium carbonate, magnesium carbonate, calcium carbonate, barium carbonate, and ammonium carbonate; aqueous solutions of bicarbonates such as sodium bicarbonate, potassium bicarbonate, magnesium bicarbonate, calcium bicarbonate, barium bicarbonate, and ammonium bicarbonate; and aqueous solutions of ammonia, tetraalkylammonium hydroxide, and hydrazine.

[0025] Furthermore, a sizing agent may be applied to the carbon fibers after liquid-phase electrolytic oxidation. The sizing agent can be appropriately selected within the range in which the effects of the present invention are exhibited, and the amount of application may be appropriately adjusted from the viewpoint of handling and higher processability. The sizing agent can be applied by known methods, and can be arbitrarily selected from the dip method, spray coating method, roll coating method, etc. From the viewpoint of uniform adhesion, the dip method is preferable. When applying the sizing agent, it is preferable to use a sizing agent-containing solution obtained by diluting the sizing agent component with a solvent. Examples of solvents include water, methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, dimethylformamide, and dimethylacetamide, but among these, an aqueous solution or an aqueous dispersion emulsified with a surfactant is preferably used because it is easy to handle and advantageous from the viewpoint of safety. Furthermore, after applying the sizing agent-containing solution to the carbon fibers, it is preferable to evaporate the solvent and dry it. Examples of heating methods include heating rollers, heated air, microwave irradiation, infrared irradiation, etc.

[0026] The carbon fiber rope of the present invention is made up of three or more strands twisted or combined together, and the drape value of the strands is 2 cm or more and 24 cm or less. The drape value is a value that represents the stiffness of the strand, and the larger the drape value, the stiffer the strand is. In some cases, if the strand is extremely stiff, it may not be possible to measure the drape value.

[0027] Setting the drape value to 2 cm or more improves the bundled properties of the strands, suppressing the unraveling of the individual carbon fibers contained in the strands even when strong external forces are applied. This effectively reflects the high strength and elastic modulus of the carbon fibers in the physical properties of the carbon fiber rope. Setting the drape value to 24 cm or less improves the flexibility of the strands, increasing the degree of freedom when bending the carbon fiber rope and improving workability. A drape value of 3 cm or more is preferable, 4 cm or more is more preferable, 23 cm or less is preferable, and 22 cm or less is even more preferable. When evaluating the drape value of the strands contained in a carbon fiber rope, the carbon fiber rope is cut to the length required for drape value evaluation, the strands are removed, and then the evaluation is performed. If the entire carbon fiber rope is covered with resin or covering threads and it is difficult to remove the strands, the resin or covering threads are physically removed before removing the strands. The drape value of the strands in this invention is measured by the method described in the examples.

[0028] Factors that affect the strand's drape value include the type and amount of sizing agent applied in the surface treatment process, whether or not the carbon fiber bundle is impregnated with resin, the type and amount of resin, and whether or not the carbon fiber bundle is covered with a covering yarn, and the type of covering yarn. However, from the perspective of controlling the strand's drape value, it is preferable to control it by the type and amount of sizing agent applied, due to the simplicity of the process and ease of control.

[0029] The carbon fiber rope of the present invention is made up of three or more strands twisted together or combined, and when one end of the strands is a fixed end and the other end is a free end that can rotate around the axis of the strands, the remaining twist angle is 1.5° or more and 7.5° or less.

[0030] In this invention, a fixed end is any part of a strand that is fixed so as not to rotate around its longitudinal axis, and can be achieved by restraining the rotation of the strand using adhesive tape or the like. In this invention, a free end is the end that appears when a continuous strand is cut in a cross section perpendicular to its longitudinal direction, and is an end that is not fixed to anything and can rotate around its longitudinal axis. In this invention, when one end of a strand is a fixed end and the other end is a free end that can rotate around the axis of the strand, the remaining twist angle is the twist angle of the semi-permanent twist that the strand has. A semi-permanent twist is a twist that does not unravel on its own without the action of an external force. In this invention, with one end as the fixed end and the other as the free end, the twist that remains unraveled after being left to stand for 5 minutes is defined as the semi-permanent twist, or remaining twist. The remaining twist angle can be calculated from the number of twists in the remaining strand, the number of filaments in the carbon fiber bundle contained in the strand, and the diameter of the single fiber. In this invention, the number of twists in the remaining strand, the diameter of the single fiber, and the remaining twist angle are measured by the method described in the examples.

[0031] Setting the remaining twist angle to 1.5° or more improves stress transfer between individual fibers within the carbon fiber bundle contained in the strand, thereby improving the tensile strength of the carbon fiber rope even when there is no or very little resin impregnation. Furthermore, setting the remaining twist angle to 7.5° or less makes it easier to utilize the high tensile strength of the individual fibers within the carbon fiber bundle contained in the strand, thereby improving the tensile strength of the carbon fiber rope. A twist angle of 1.8° or more is more preferable, 2.0° or more is even more preferable, 6.5° or less is more preferable, and 5.5° or less is even more preferable.

[0032] Regarding the method for maintaining a remaining twist angle of 1.5° or more and 7.5° or less, there are methods such as adding twist to the carbon fiber bundle afterwards and then fixing it by resin impregnation or coating, and adding twist to the precursor fiber bundle during the flame-retardant process to create a twisted shape. The latter method is preferable. The method of adding twist and then fixing it by resin impregnation or coating reduces the flexibility of the strand, but the method of adding twist during the flame-retardant process to create a twisted shape allows the remaining twist angle to be maintained without compromising flexibility due to resin impregnation or coating, making it easier to achieve both high workability and high tensile strength in carbon fiber ropes. Furthermore, adding twist during the flame-retardant process suppresses slack in the single fibers within the carbon fiber bundle in the twisted state, further improving stress transmission between single fibers within the carbon fiber bundle and making it easier to improve the tensile strength of the carbon fiber rope even when there is no resin impregnation or very little.

[0033] Furthermore, methods for imparting twist to the precursor fiber bundle during the flame-retardant treatment process include winding the precursor fiber bundle onto a bobbin and then rotating the bobbin perpendicular to the winding direction when unwinding the fiber bundle, or contacting the fiber bundle with a rotating roller or belt while it is moving without winding it onto a bobbin, thereby adding a desired number of twists.

[0034] In the carbon fiber rope of the present invention, it is preferable that the specific modulus of elasticity RM (GPA), obtained by dividing the elastic modulus SM (GPA) of the strand by the specific gravity α(-) of the strand, satisfies formula (1). 120 ≤ RM ≤ 300 ... formula (1) Setting the specific modulus of elasticity RM to 120 GPa or higher makes it possible to reduce the weight of the carbon fiber rope while maintaining its rigidity, thus improving workability. Setting the specific modulus of elasticity RM to 300 GPa or lower provides a good balance between the rigidity and strength of the carbon fiber rope, making it easier to effectively generate strength. A specific modulus of elasticity RM of 140 GPa or higher is more preferable, 160 GPa or higher is even more preferable, 200 GPa is particularly preferable, 280 GPa or lower is more preferable, and 260 GPa or lower is even more preferable. To determine the elastic modulus of the strands contained in the carbon fiber rope, the carbon fiber rope is cut to the length required for the tensile test, the strands are removed, and then evaluated. Furthermore, if the entire carbon fiber rope is covered with resin or coating threads and the strands are difficult to remove, the resin or coating threads are physically removed before the strands are removed. If the strands are a carbon fiber composite material in which carbon fiber bundles are impregnated with resin, the elastic modulus is evaluated using the composite material as a test piece. If the strands are carbon fiber bundles without resin impregnation, the elastic modulus is evaluated using a test piece obtained by resin impregnation. The elastic modulus SM and specific gravity α of the strands in this invention are measured by the method described in the examples, and the specific modulus RM is calculated from these values. However, in the case where the strands are carbon fiber bundles without resin impregnation, the composition in the resin formulation used to evaluate the elastic modulus may be an epoxy resin / boron trifluoride monoethylamine / acetone = 100 / 3 / 4 (parts by weight) containing 97% by weight or more of (3',4'-epoxycyclohexane)methyl-3,4-epoxycyclohexylcarboxylate, with an epoxy equivalent of 130 g / eq and a viscosity of 240 mPa·s at 25°C.

[0035] The carbon fiber rope of the present invention preferably satisfies the following conditions: the bundle strength BS (GPa) of the carbon fiber bundles contained in the strand is 1.5 GPa or more and 10 GPa or less, and the strength ratio β (-) obtained by dividing the bundle strength BS (GPa) by the tensile strength TS (GPa) satisfies the formula (2). 0.40 ≤ β ≤ 1.00 ··· formula (2) When the bundle strength of the carbon fiber bundles contained in the strand is 1.5 GPa or more, it becomes easier to improve the tensile strength as a carbon fiber rope. Also, when the bundle strength of the carbon fiber bundles contained in the strand is 10 GPa or less, the balance between the rigidity and strength of the carbon fiber rope becomes good, and the strength can be effectively exhibited. The bundle strength is more preferably 2.0 GPa or more, further preferably 2.5 GPa or more, more preferably 8 GPa or less, and further preferably 6 GPa or less.

[0036] When the strength ratio obtained by dividing the bundle strength by the tensile strength is 0.40 or more, it becomes easier to effectively improve the tensile strength as a carbon fiber rope even when there is no resin impregnation or when the resin impregnation is very small. Also, when the strength ratio obtained by dividing the bundle strength by the tensile strength is 1.00 or less, it becomes easier to improve the workability as a carbon fiber rope. The strength ratio is more preferably 0.45 or more, further preferably 0.50 or more, more preferably 0.95 or less, and further preferably 0.90 or less.

[0037] Here, when obtaining the bundle strength and tensile strength of the carbon fiber bundles contained in the strand, the carbon fiber rope is cut to the length required for evaluation, and the strand is taken out for evaluation. When the entire carbon fiber rope is coated with resin or covering yarn and it is difficult to take out the strand, the resin or covering yarn is physically removed and then the strand is taken out. Also, when the carbon fiber bundles contained in the strand are resin-impregnated or coated with covering yarn, the resin or covering yarn is removed by methods such as physically separating, dissolving with a solvent, or burning off at a high temperature in a nitrogen atmosphere, and then the carbon fiber bundles are taken out.

[0038] Note that the bundle strength, tensile strength, and strength ratio of the carbon fiber bundles contained in the strands in the present invention are measured by the method described in the examples. However, as the composition in the resin formulation when evaluating the tensile strength, any composition may be used as long as it is the composition described above with respect to the elastic modulus in the case where the strand is a carbon fiber bundle without resin impregnation.

[0039] The carbon fiber rope of the present invention preferably has a weight ratio of the carbon fibers contained in the above strands of 90.0% by weight or more and 99.9% by weight or less. By setting the weight ratio of the carbon fibers contained in the strands in the carbon fiber rope to 90.0% by weight or more, it becomes easier to improve the flexibility of the carbon fiber rope and to improve the workability. Also, by setting the weight ratio of the carbon fibers contained in the strands in the carbon fiber rope to 99.9% by weight or less, it becomes easier to suppress single fiber breakage due to excessive rubbing between the single fibers of the carbon fiber, and it becomes easier to suppress a decrease in the strength of the carbon fiber rope when used for a long time. The weight ratio of the carbon fibers is more preferably 95.0% by weight or more, and even more preferably 98.0% by weight or more. Also, the weight ratio of the carbon fibers is more preferably 99.8% by weight or less, even more preferably 99.5% by weight or less, and particularly preferably 99.2% by weight or less.

[0040] The carbon fiber rope of the present invention has a cross-sectional area A of the carbon fiber bundle contained in the above strand of 0.2 mm ２ or more and 2.0 mm ２ or less. By setting the cross-sectional area of the carbon fiber bundle contained in the strand in the carbon fiber rope to 0.2 mm ２ or more, it is possible to efficiently increase the twist angle of the strand even with a small number of twists, so it becomes easier to improve the stress transmission between the single fibers in the carbon fiber bundle, and it becomes easier to improve the tensile strength as the carbon fiber rope. Also, by setting the cross-sectional area of the carbon fiber bundle contained in the strand in the carbon fiber rope to 2.0 mm ２ or less, it becomes easier to improve the flexibility of the carbon fiber rope and to improve the workability. The cross-sectional area of the carbon fiber bundle contained in the strand is more preferably 0.3 mm ２ or more, even more preferably 0.4 mm ２ or more, and also 1.5 mm ２The following is more preferable, 1.0 mm ２ The following is even more preferable. The cross-sectional area of the carbon fiber bundle included in the strand in the present invention is measured by the method described in the examples.

[0041] It is preferable that the single fiber diameter of the carbon fiber included in the above strand of the carbon fiber rope of the present invention is 4 μm or more and less than 6 μm. When the single fiber diameter of the carbon fiber is 4 μm or more, it becomes easier to increase the twist angle and easier to improve the tensile strength as the carbon fiber rope. Further, when the single fiber diameter of the carbon fiber is less than 6 μm, it becomes easier to improve the tensile strength and elastic modulus of the carbon fiber, and easier to improve the tensile strength and specific elastic modulus as the carbon fiber rope. The single fiber diameter is more preferably 4.5 μm or more, even more preferably 5 μm or more, more preferably 5.8 μm or less, and even more preferably 5.6 μm or less. The single fiber diameter of the carbon fiber in the present invention is measured by the method described in the examples.

[0042] It is preferable that the total length of the carbon fiber rope of the present invention is 3000 m or more. When the total length of the carbon fiber rope is 3000 m or more, it becomes easier to apply it to the use over a long distance, which is an advantage of the carbon fiber rope. Since the carbon fiber rope is lightweight, it is easy to suppress the strength reduction due to the influence of its own weight even when used over a long distance, and it is easy to maintain high strength. The total length is more preferably 5000 m or more, even more preferably 7000 m or more, and particularly preferably 9000 m or more. The upper limit is not particularly limited, but from the viewpoint of making the winding shape compact, it may be 30000 m or less.

[0043] <Infrastructure Material Using Carbon Fiber Rope> The infrastructure material using carbon fiber rope of the present invention is preferably an earthquake-resistant reinforcement material. By including the carbon fiber rope of the present invention, high strength can be achieved even in applications where rigidity is required, such as earthquake-resistant reinforcement materials for steel-framed buildings, making it easier to reduce the amount used as an earthquake-resistant reinforcement material. Furthermore, because it is lightweight due to its high specific modulus of elasticity and highly flexible, it is easy to transport by reducing the winding diameter of the earthquake-resistant reinforcement material, and it is possible to make it easier to unwind during installation, thus improving workability and making it easier to shorten the construction period. The earthquake-resistant reinforcement material of the present invention may include only the joining member between the carbon fiber rope of the present invention and the object to be reinforced, or it may include a small amount of material such as a covering material.

[0044] The infrastructure material using the carbon fiber rope of the present invention is preferably an electric wire cable. By including the carbon fiber rope of the present invention, high strength can be achieved even in applications where rigidity is required, such as the core material of an electric wire cable. This allows for the support of more conductive wires than conventional methods without changing the thickness of the core material, making it easier to increase the power transmission capacity. Furthermore, because it is lightweight due to its high specific modulus of elasticity and highly flexible, it is easy to transport by reducing the winding diameter of the electric wire cable, and unwinding during installation can be made faster, resulting in excellent workability and making it easier to shorten the construction period. The electric wire cable of the present invention may contain only the core material containing the carbon fiber rope of the present invention and conductive wires, or it may also contain components such as a covering material.

[0045] The infrastructure material using the carbon fiber rope of the present invention is preferably a bridge cable. By including the carbon fiber rope of the present invention, high strength can be achieved even in applications requiring rigidity, such as suspension members for suspension bridges and cable-stayed bridges, making it easier to support large main girders without changing the number of bridge cables. Furthermore, because it is lightweight due to its high specific modulus of elasticity and highly flexible, it is easy to transport by reducing the winding diameter of the bridge cable, and unwinding during installation can be made faster, resulting in excellent workability and making it easier to shorten the construction period. In the bridge cable of the present invention, only the connecting members between the carbon fiber rope of the present invention and the main girders or towers may be included, or small amounts of members such as covering materials may be included.

[0046] The infrastructure material using the carbon fiber rope of the present invention is preferably a mooring rope. By including the carbon fiber rope of the present invention, high strength can be achieved even in applications where rigidity is required, such as mooring ropes for large ships and floating offshore wind turbines, making it easier to secure large floating structures without increasing the thickness or number of mooring ropes. Furthermore, because it is lightweight due to its high specific modulus of elasticity and highly flexible, it is possible to improve ease of transport by reducing the winding diameter of the mooring rope and to unwind it more quickly during installation. The mooring rope of the present invention may contain only the carbon fiber rope of the present invention, or it may contain a small amount of components such as a covering material.

[0047] The infrastructure material using the carbon fiber rope of the present invention is preferably a tensioning material for civil engineering and construction. By including the carbon fiber rope of the present invention, high strength can be achieved even in applications requiring rigidity, such as tensioning materials for large prestressed concrete. Therefore, when applying tension with a jack, the high modulus of elasticity can be used to suppress the required strain range, making it easier to increase the degree of freedom during construction. Furthermore, because it is lightweight due to its high specific modulus of elasticity and highly flexible, it is easy to transport by reducing the winding diameter of the tensioning material for civil engineering and construction, and it is possible to unwind it more quickly during installation, resulting in excellent workability and making it easier to shorten the construction period. The tensioning material for civil engineering and construction of the present invention may contain only the carbon fiber rope of the present invention, or it may contain a small amount of other components such as a covering material.

[0048] <Power transmission equipment including power cables using carbon fiber rope> The power transmission equipment including power cables using carbon fiber rope of the present invention is preferably a power transmission equipment in which the distance between tower support points is 1,000 m or more. The power cables using carbon fiber rope of the present invention are suitable for applications with long distances between tower support points because they easily suppress the reduction in strength due to the effect of their own weight even when used over long distances, and can be used in power transmission equipment in which the distance between tower support points is 1,000 m or more. When the distance between tower support points is 1,000 m or more, it becomes easier to reduce the number of towers required for power transmission and to realize power transmission in locations where it is difficult to erect towers. The distance between tower support points is more preferably 2,000 m or more, and even more preferably 3,000 m or more. There is no particular upper limit, but from the viewpoint of suppressing the deflection of the power cables, it is fine as long as it is 10,000 m or less.

[0049] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these examples. The methods for measuring and evaluating each physical property are as follows.

[0050] <Strand Drape Value> First, take one strand from a carbon fiber rope cut to any length. Next, cut the strand to a length of 30 cm and, in an atmosphere of 25°C, place the strand 2 on a rectangular horizontal stand 4 with 90° corners, as shown in Figure 2, so that 25 cm of the strand extends beyond the stand, while supporting it to prevent it from bending. Secure the strand 2 on the horizontal stand 4 with tape. Then, remove the support from the end (fulcrum) of the horizontal stand 4 and let the strand hang down. After 1 second, measure the horizontal distance L (cm) from the fulcrum to the tip of the strand, and take the average of n (5) measurements as the drape value. A larger drape value indicates that the strand has stiffer properties.

[0051] <Strand Modulus of Elasticity> The modulus of elasticity of the strand is determined in accordance with the tensile property test method of JIS R7608 (2007) and follows the procedure below. If the strand is a carbon fiber bundle without resin impregnation, test specimens are prepared by resin impregnation and curing as described below. If the carbon fiber bundle has twist, it is evaluated after untwisting by applying the same number of reverse twists as the number of twists. The resin formulation used is "Celoxide (registered trademark)" 2021P (manufactured by Daicel Corporation) / boron trifluoride monoethylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) / acetone = 100 / 3 / 4 (parts by weight), and the curing conditions are atmospheric pressure, temperature 125°C, and time 30 minutes. Ten test specimens were measured, and the average value was taken as the modulus of elasticity of the strand. The strain range when calculating the tensile modulus of elasticity was set to 0.1 to 0.6%.

[0052] <Specific Gravity of Strands> Strands are extracted from carbon fiber rope cut to a desired size, and their specific gravity is measured using the Archimedes method with o-dichlorobenzene as the specific gravity solution. The measurement is performed in a constant temperature environment at room temperature of 25°C.

[0053] <Specific Modulus of the Strand> The specific modulus of the strand is calculated from the modulus of elasticity (GPa) of the strand and the specific gravity of the strand (-) using the following formula: Specific modulus of elasticity of the strand (GPa) = Modulus of elasticity of the strand (GPa) ÷ Specific gravity of the strand (-) <Single fiber diameter of carbon fibers contained in the strand> The single fibers of carbon fibers contained in the strand are evaluated by observing them with a scanning electron microscope (SEM). Fifty single fibers are evaluated, and the average value of the diameters of these single fibers is taken as the single fiber diameter. In this example, observation was performed using the SEM "S-4800" manufactured by Hitachi High-Technologies Corporation.

[0054] <Cross-sectional area of ​​carbon fiber bundles contained in a strand> The cross-sectional area of ​​the carbon fiber bundle is calculated from the single fiber diameter (μm) of the carbon fiber contained in the strand and the number of filaments in the carbon fiber bundle contained in the strand using the following formula: Cross-sectional area of ​​carbon fiber bundle A (mm²) ２ ) = π × (Diameter of carbon fiber single filament ÷ 2) ２ × Number of filaments in the carbon fiber bundle × 10 －６ <Weight percentage of carbon fibers in the strands> Strands were taken from a carbon fiber rope cut to an arbitrary size, their weight was measured, and then they were placed in an electric furnace with a nitrogen atmosphere set to a temperature of 450°C to burn off components other than carbon fibers. The weight of the resulting carbon fibers was then measured to determine the weight percentage of carbon fibers. <Amount of sizing agent adhering to carbon fiber bundles in carbon fiber rope> For carbon fiber bundles used in carbon fiber rope, they were cut to an arbitrary length and weighed (W1), then placed in an electric furnace with a nitrogen atmosphere set to a temperature of 450°C to thermally decompose the sizing agent, and the resulting carbon fiber bundles were weighed (W2). The weight loss due to heating was calculated by subtracting W2. The value obtained by converting this weight loss due to heating to a weight percentage in the carbon fiber bundle was defined as the amount of sizing agent adhering to the carbon fiber bundle (weight %).

[0055] <Number of remaining twists in the strand> A guide bar is set at a height of 60 cm from the horizontal plane, and a fixed end is created by attaching an arbitrary position of the strand to the guide bar with adhesive tape. With the strand suspended vertically from the guide bar, the strand is cut at a point 50 cm below the fixed end to form a free end. The free end is sealed by sandwiching it with adhesive tape to prevent it from unraveling into individual fibers. In order to exclude temporary twists or twists that return over time from the measured number of twists, the strand is left to stand for 5 minutes in this state, and the number of twists n contained in 50 cm of the strand is visually counted. Then, the number of remaining twists is calculated using the following formula. The average of the above measurement performed three times is taken as the number of remaining twists in the strand in this invention. Number of remaining twists (turns / m) = n (turns) / 0.5 (m) <Remaining twist angle of the strand> After calculating the overall diameter of the strand (μm) from the single filament diameter (μm) of the carbon fiber contained in the strand and the number of filaments in the carbon fiber bundle using the following formula, the remaining twist angle (°) of the strand is calculated using the number of remaining twists (turns / m) using the following formula. Overall diameter of the strand (μm) = {(single filament diameter of carbon fiber) ２ × Number of filaments ０．５ The remaining twist angle of the strand (°) = atan(total diameter of the strand × 10) －６(xπ x number of remaining twists) <Bundle strength of carbon fiber bundles contained in the strand> The bundle strength of carbon fiber bundles contained in the strand was measured using a Tensilon universal material tester RTC-1210A (manufactured by A&D Co., Ltd.) with a chuck distance of 500 mm, a crosshead speed of 100 mm / min, and a sample size n=10. <Tensile strength of carbon fiber bundles contained in the strand> The tensile strength of carbon fiber bundles contained in the strand was determined in accordance with the tensile properties test method of JIS R7608 (2007) and followed the procedure below. However, if the carbon fiber bundle has twists, it is evaluated after untwisting by applying the same number of reverse twists as the number of twists. The resin formulation used was "Celoxide (registered trademark)" 2021P (manufactured by Daicel Corporation) / boron trifluoride monoethylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) / acetone = 100 / 3 / 4 (parts by weight). The curing conditions were atmospheric pressure, temperature 125°C, and time 30 minutes. Ten test specimens were measured, and the average value was taken as the tensile strength.

[0056] <Workability of Carbon Fiber Rope> The workability of a carbon fiber rope consisting of seven strands was evaluated according to the following criteria: A: Even when the carbon fiber rope is wound onto a 10 cm diameter bobbin or bent freely in various directions at multiple points like a string game, the carbon fiber bundles contained in the strands do not break, and the deformed shape can be maintained without applying any external force. B: Even when the carbon fiber rope is wound onto a 10 cm diameter bobbin or bent freely in various directions at multiple points like a string game, the carbon fiber bundles contained in the strands do not break, but an external force is required to maintain the deformed shape. C: The carbon fiber rope cannot be wound onto a 10 cm diameter bobbin or bent freely like a string game, and the carbon fiber bundles contained in the strands break.

[0057] <Sizing Agents> The sizing agents used in each example are as follows: Sizing agent D-1: Polyethylene glycol (PEG600, HLB: 20, molecular weight: 600, manufactured by Sanyo Chemical Industries, Ltd.) Sizing agent D-2: Bisphenol A epoxy ("jER®" 828, manufactured by Mitsubishi Chemical Corporation) (Example 1) A polyacrylonitrile-based carbon fiber precursor fiber bundle with a single fiber fineness of 0.8 dtex obtained by a known method was bonded to 12,000 single fibers, a twist of 21 turns / m was applied, and the bundle was heat-treated in an oven at 230-280°C in an air atmosphere to convert it into a flame-resistant fiber bundle. Next, the obtained flame-resistant fiber bundle was subjected to a pre-carbonization treatment in a nitrogen atmosphere at a temperature of 300-800°C to obtain a pre-carbonized fiber bundle. Next, the preliminary carbonized fiber bundles were subjected to carbonization treatment at the maximum carbonization temperature of 1400°C and a stretch ratio of 0.96 as shown in Table 1. Then, an electrolytic surface treatment was performed using an aqueous sulfuric acid solution as the electrolyte at an electrical charge of 45 C / g, followed by washing with water, application of a sizing agent, and drying in heated air to obtain carbon fiber bundles. The amount of sizing agent applied was such that the amount of sizing agent attached to the carbon fiber bundle was 0.3% by weight, with the total carbon fiber bundle being 100% by weight. D-1 [polyethylene glycol (PEG600, HLB: 20, molecular weight: 600, manufactured by Sanyo Chemical Industries, Ltd.)] was used as the sizing agent. The evaluation results of the obtained carbon fiber bundles are shown in Table 1. Furthermore, a carbon fiber rope was fabricated by twisting seven strands of the obtained carbon fiber bundles together. The evaluation results of the strands and carbon fiber rope are shown in Table 2. Together with the results in Table 1, it was confirmed that a carbon fiber rope that balances strength and workability was obtained.

[0058] (Examples 2) to (Examples 9) The same procedure as in Example 1 was followed, except that the manufacturing conditions for the carbon fiber bundles were changed as shown in Table 1. The evaluation results for the obtained carbon fiber bundles, strands, and carbon fiber ropes are shown in Tables 1 and 2, confirming that carbon fiber ropes that balance strength and workability were obtained.

[0059] (Example 10) The procedure was carried out in the same manner as in Example 1, except that seven strands of the obtained carbon fiber bundles were bundled in parallel and placed in a heat-shrinkable tube (made of polyolefin resin, with an inner diameter of 5.6 mm before shrinking) and then heated to produce a carbon fiber rope. The evaluation results of the obtained carbon fiber bundles, strands, and carbon fiber rope are shown in Tables 1 and 2, and it was confirmed that a carbon fiber rope with high strength was obtained, although its workability was slightly inferior.

[0060] (Comparative Example 1) A carbon fiber rope consisting of seven strands was produced by impregnating the carbon fiber bundle obtained in Example 1 with resin, then twisting the seven strands together and curing the mixture. The resin formulation used was "Celoxide (registered trademark)" 2021P (manufactured by Daicel Corporation) / boron trifluoride monoethylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) / acetone = 100 / 3 / 4 (parts by weight), and the curing conditions were atmospheric pressure, temperature 125°C, and time 30 minutes. The evaluation results of the carbon fiber bundle, strands, and carbon fiber rope are shown in Tables 1 and 2, and it was confirmed that the resulting carbon fiber rope lacked flexibility and had poor workability.

[0061] (Comparative Example 2) Using Toray Industries, Inc.'s "Torayca (registered trademark)" T700SC-12000, strands were prepared by applying a twist of 60 turns / m. Seven of the resulting strands were then twisted together and placed in a heat-shrinkable tube (made of polyolefin resin, with an inner diameter of 5.6 mm before shrinking) and heated to produce a carbon fiber rope. Although twist was applied, no fixing treatment was performed, so no remaining twist was observed. The evaluation results for the carbon fiber bundle, strands, and carbon fiber rope are shown in Tables 1 and 2. It was confirmed that the resulting carbon fiber rope did not easily develop strength and was somewhat inferior in terms of workability.

[0062] (Comparative Example 3) Using Toray Industries, Inc.'s "Torayca®" T700SC-24000, a carbon fiber rope consisting of seven strands was produced by impregnating it with resin after adding a twist of 30 turns / m, then twisting seven strands together and curing it. The resin formulation used was "Celoxide®" 2021P (manufactured by Daicel Corporation) / boron trifluoride monoethylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) / acetone = 100 / 3 / 4 (parts by weight), and the curing conditions were atmospheric pressure, temperature 125°C, and time 30 minutes. The evaluation results of the carbon fiber bundle, strands, and carbon fiber rope are shown in Tables 1 and 2, confirming that the resulting carbon fiber rope had poor strength development and poor workability.

[0063]

[0064]

[0065] 1: Carbon fiber rope 2: Strand 3: Single fiber 4: Horizontal platform

Claims

1. A carbon fiber rope comprising three or more strands twisted or combined, wherein each strand satisfies (i) to (iii): (i) Each strand contains a bundle of carbon fibers. (ii) The drape value of the strand is 2 cm or more and 24 cm or less. (iii) When one end of the strand is a fixed end and the other end is a free end that can rotate around the axis of the strand, the remaining twist angle is 1.5° or more and 7.5° or less.

2. The carbon fiber rope according to claim 1, wherein the specific modulus RM (GPa), obtained by dividing the elastic modulus SM (GPa) of the strand by the specific gravity α(-) of the strand, satisfies formula (1): 120 ≤ RM ≤ 300 ... formula (1) 3. The carbon fiber rope according to claim 1 or claim 2, wherein the bundle strength BS (GPA) of the carbon fiber bundle contained in the strand is 1.5 GPa or more and 10 GPa or less, and the strength ratio β(-) obtained by dividing the bundle strength BS (GPA) by the tensile strength TS (GPA) satisfies formula (2): 0.40 ≤ β ≤ 1.00 ... formula (2) 4. The carbon fiber rope according to claim 1 or claim 2, wherein the weight percentage of carbon fibers contained in the strand is 90.0% by weight or more and 99.9% by weight or less.

5. The cross-sectional area A of the carbon fiber bundle contained in the strand is 0.2 mm². ２ Above, 2.0 mm ２ The carbon fiber rope according to claim 1 or claim 2, which is as follows:

6. The carbon fiber rope according to claim 1 or claim 2, wherein the single filament diameter of the carbon fibers contained in the strand is 4 μm or more and less than 6 μm.

7. The carbon fiber rope according to claim 1 or claim 2, wherein the total length is 3,000 m or more.

8. An infrastructure material using the carbon fiber rope according to claim 1 or claim 2.

9. Electrical cable using carbon fiber rope according to claim 1 or claim 2.

10. A power transmission facility comprising the electric wire cable described in claim 9, wherein the distance between tower support points is 1,000 m or more.

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