Composite covering yarn and rope made from same

Abstract

To provide a composite covering yarn having high elasticity, high strength, lightness, and also a good creep resistance and thereby breaking risk due to tension change and aging is reduced.SOLUTION: A composite covering yarn consists of a core yarn and a sheath yarn covering the core yarn. The core yarn is formed of fibers having tensile elongation at break of 15% or higher. The sheath yarn is formed of fibers having tensile elongation at break of 14% or less. Covering angle θ is 0.30 to 0.49 radian.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a composite covered yarn and a rope, and more particularly to a composite covered yarn made of a plurality of types of fibers and a rope made of the same. [Background technology]

[0002] The mooring and unmooring process is a fundamental activity that supports port operations. To ensure the safety of this process, it is extremely important to ensure ease of mooring while reducing the risk of mooring rope breakage.

[0003] Generally, mooring ropes are used in environments where the ship moves up and down significantly, so the magnitude of the tension fluctuations on the rope is a particularly important factor in considering the risk of breakage. In order to reduce the risk of breakage due to tension fluctuations, it is effective to have a design concept in which the mooring rope itself stretches to absorb the tension fluctuations. Based on this concept, nylon ropes, which are expected to have high elongation, are currently mainly used.

[0004] However, nylon has a specific gravity of over 1, and nylon mooring ropes do not float on water, posing a problem in terms of mooring workability. Furthermore, nylon has poor creep resistance, so there is concern about the high risk of breakage over time.

[0005] One possible solution to the above problems is the use of ropes made of polyolefin-based materials (Patent Document 1). Although polyolefin-based ropes can achieve both high elongation and low specific gravity, concerns about creep resistance remain.

[0006] In order to achieve good creep resistance, it is possible to use a rope made of aramid fiber (Patent Document 2). However, since an aramid fiber rope has a low specific gravity and does not float on seawater, and furthermore, has a low breaking elongation, it is difficult to respond to a sudden change in tension by stretching the rope. As described above, a mooring rope that combines high elongation, high strength, and light weight is desirable, but at present no effective material system that satisfies all of these requirements has been proposed. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2007-254941 A [Patent Document 2] Patent No. 4787508 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention aims to provide a composite covering yarn that has high elongation, high strength, and light weight, as well as good creep resistance, thereby reducing the risk of breakage due to tension changes and aging. [Means for solving the problem]

[0009] That is, the present invention provides: A composite covered yarn comprising a core yarn and a sheath yarn covering the core yarn, The core yarn is made of fibers having a tensile breaking elongation of 15% or more, and the sheath yarn is made of fibers having a tensile breaking elongation of 14% or less, This is a composite covering yarn characterized in that the covering angle θ calculated by the following formula is 0.30 to 0.49 radians.

[0010]

number

[0011] Where: θ: Covering angle (radian) D: Core yarn diameter (cm) d: Sheath diameter (cm) T: Number of sheath thread twists (T / m) Effect of the Invention

[0012] According to the present invention, it is possible to provide a composite covering yarn that has high elongation, high strength, light weight, and also has good creep resistance, thereby reducing the risk of breakage due to tension changes and aging. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described in detail.

[0014] [Covering] The composite covered yarn of the present invention comprises a core yarn and a sheath yarn covering the core yarn. Covering with a sheath yarn is a mode in which the sheath yarn is wound around the outer circumference of a core yarn that maintains its linearity. This mode makes it easy to obtain a geometric extension allowance for the sheath yarn, and can obtain a higher elongation than conventional plied yarns, and can absorb stress by elongation when there is a tension fluctuation due to the external environment. Therefore, breakage can be reduced. This covering is different from the plied yarn configuration in which the yarns are twisted together.

[0015] The covering angle θ of the composite covered yarn of the present invention is 0.30 to 0.49 radians, preferably 0.30 to 0.44 radians. If the covering angle θ is less than 0.30 radians, the geometrical elongation allowance of the sheath yarn is not sufficiently secured, making it difficult to achieve high elongation as a composite yarn. On the other hand, if the covering angle θ exceeds 0.49 radians, the strength utilization rate of the sheath yarn decreases due to the orientation angle of the fibers, making it difficult to achieve sufficient strength as a composite covered yarn.

[0016] [Coiling thread] The core yarn is made of fibers with a tensile breaking elongation of 15% or more. If the tensile breaking elongation of the core yarn is less than 15%, the composite covering yarn will reach a breaking point before the strength of the sheath yarn is fully utilized, and therefore high strength cannot be obtained. For this core thread, organic polymer fibers having a tensile breaking elongation of 15% or more can be used, but from the viewpoint of obtaining high elongation and light weight, polyolefin fibers are preferably used.

[0017] [Sheath thread] The sheath yarn is made of fibers with a tensile breaking elongation of 14% or less. If the tensile breaking elongation of the sheath yarn exceeds 14%, the elongation of the sheath yarn approaches that of the core yarn, undesirably reducing the region in which the sheath yarn bears mechanical strength.

[0018] For this sheath thread, an organic polymer filament with a tensile breaking elongation of 14% or less is used, for example, fibers or linear films of fully aromatic polyamide, polyethylene, liquid crystal polyester, polyarylate, and polyparaphenylene benzobis oxazole can be used. From the viewpoints of strength and creep resistance, it is preferable to use wholly aromatic polyamide fibers, and it is particularly preferable to use para-aromatic polyamide fibers.

[0019] Examples of this para-type aromatic polyamide fiber include polyparaphenylene terephthalamide fiber (Twaron (registered trademark) manufactured by Teijin Aramid Co., Ltd.) and copolymer type para-aramid fiber having 3,4'-oxydiphenylenediamine or 4,4'-oxydiphenylenediamine as a copolymer component (for example, copolyparaphenylene-3,4'-oxydiphenylene terephthalamide fiber, Technora manufactured by Teijin Co., Ltd.).

[0020] When the organic polymer linear body is a fiber, it may be a multifilament or a monofilament.When it is a linear film, it may be a slit film or a tape, or may be a linear body formed by twisting these.

[0021] The sheath yarn has a tensile strength of preferably 18 to 60 cN / dtex, more preferably 20 to 50 cN / dtex, and particularly preferably 22 to 40 cN / dtex. If the tensile strength is less than 18 cN / dtex, it is not preferable because the strength cannot be obtained when the composite yarn is used to form a rope. On the other hand, if the tensile strength exceeds 60 cN / dtex, it becomes difficult for the rope to obtain flexibility and bendability. PAN-based carbon fibers have a tensile strength exceeding 60 cN / dtex.

[0022] [Physical Properties] From the viewpoint of reducing breakage during fluctuations in tension, the composite covering yarn of the present invention preferably has a tensile elongation at break of 7% or more, more preferably 9% or more. From the viewpoint of durability against large tension, the composite covering yarn of the present invention preferably has a tensile breaking strength of 8 cN / dtex or more, more preferably 9.5 cN / dtex. The composite covering yarn of the present invention preferably has an average specific gravity of 1.06 or less, more preferably 1.025 or less, from the viewpoint of ensuring good workability and handling properties as a mooring rope.

[0023] [Mooring rope] The composite covered yarn of the present invention can be suitably used as a mooring rope. That is, the present invention provides a mooring rope made of the above-mentioned composite covered yarn. EXAMPLES

[0024] The present invention will now be described in more detail with reference to examples. Evaluations were carried out in the following manner. (1) Tensile elongation at break and tensile strength The samples were measured using a tensile tester (manufactured by INSTRON, product name: INSTRON) in accordance with ASTM D885 under the following conditions. Temperature: 25℃ Measurement sample length: 750mm Tensile speed: 250mm / min Chuck distance: 500mm

[0025] (2) Average specific gravity The average specific gravity ρ (Ave) was calculated using the following formula.

[0026]

number

[0027] Dtex(Total): Total fiber count (dtex) S(Total): Total cross-sectional area (cm 2 ) Dtex (Total) was calculated from the sum of the fineness (dtex) of the core yarn and the sheath yarn. S(Total) is the cross-sectional area of ​​each of the core and sheath yarns (cm 2 ) was calculated. The cross-sectional area of ​​the core yarn and the sheath yarn (cm 2 ) was calculated using the following formula:

[0028]

number

[0029] S(Core): Cross-sectional area of ​​the core thread (cm 2 ) Dtex(Core): The fineness of the core thread (dtex) ρ(Core): Density of core thread (g / cm 3 )

[0030]

number

[0031] S(sheath): Cross-sectional area of ​​sheath thread (cm 2 ) Dtex (sheath): sheath thread fineness (dtex) ρ (sheath): Density of sheath thread (g / cm 3 )

[0032] (3) Creep resistance A load equivalent to 40% of the breaking load was applied to the sample at a temperature of 20°C, and the elongation rate (%) of the test piece between 40 minutes and 70 minutes after the test load was applied was divided by the test time (30 minutes) to obtain the creep rate (% / min). Creep resistance was evaluated according to the following criteria. Good (Good): Creep rate is 1×10 -3 Less than % / min ×(Poor): Creep rate is 1×10 -3 % / min or more

[0033] (4) Tensile test of braided rope A braided rope (rope length: 1 m) with eyes on both ends was used as the specimen. In the tensile test, in order to take into account the tightening effect of the rope structure due to tension, the braided rope was stretched and tightened up to the point where the load-strain curve of the braided rope begins to rise, and then the load was removed to the initial state and it was stretched again.

[0034] (5) Creep resistance of braided ropes A braided rope (rope length: 1 m) with eyes at both ends was used as the specimen. A load equivalent to 40% of the breaking load was applied at a temperature of 20°C, and the elongation rate (%) of the test piece between 40 minutes and 70 minutes after the test load was applied was divided by the test time (30 minutes) to obtain the tensile strength. The creep resistance of the braided rope was evaluated according to the following criteria: Good (Good): Creep rate is 1×10 -3 Less than % / min ×(Poor): Creep rate is 1×10 -3 % / min or more

[0035] Example 1 A composite covered yarn (total fineness: 3300 dtex) was produced using polypropylene fiber (fineness: 1100 dtex, number of fiber bundles: 2, twisting conditions: Z50 T / m) as the core yarn and aramid fiber (Technora (registered trademark) manufactured by Teijin Ltd., product number: T221 1100T / 667, number of fiber bundles: 1, number of single yarns in the fiber bundle: 667, twisting conditions: S160 T / m) as the sheath yarn. The covering angle θ of this composite covered yarn was 0.41 radians. The tensile breaking elongation, tensile strength, average specific gravity, and creep resistance of the produced composite covered yarn were evaluated.

[0036] Next, using the above-mentioned composite covering yarn, two strands were first twisted, and then six strands were second twisted to create a filament bundle with a total of 12 strands twisted together. The second twisting condition was 40 T / m. 24 strands of this filament bundle were twisted together at 14 T / m to create a strand. The total fineness of the resulting strand was 950,000 dtex. Six pairs of these strands were used to create a 12-strand braided rope with a total fineness of 11,400,000 dtex consisting of 12 strands, and the tensile breaking elongation, tensile strength, and creep resistance were evaluated.

[0037] Example 2 In Example 1, the configuration of the core yarn and the sheath yarn and the covering conditions were changed. Specifically, the number of strands of the polypropylene fiber used as the core yarn was set to 3, the twisting conditions were set to Z33T / m, the part number of the aramid fiber (Technora (registered trademark) manufactured by Teijin Limited) used as the sheath yarn was set to T221 1670T / 1000 (number of single yarns in the fiber bundle: 1,000), and the twisting conditions of the sheath yarn were set to S90T / m. The covering angle θ of the composite covering yarn was set to 0.30 radians. The prepared composite covering yarn was evaluated in the same manner as in Example 1. Furthermore, a 12-strand braided rope was prepared in the same manner as in Example 1, and the tensile breaking elongation, tensile strength, and creep resistance were evaluated.

[0038] Comparative Example 1 The polypropylene fiber used as the core yarn in Example 1 was prepared, and the physical properties of this polypropylene fiber alone were evaluated. A 12-strand braided rope was prepared in the same manner as in Example 1, except that this polypropylene fiber was used instead of the composite covering yarn, and the tensile breaking elongation, tensile strength, and creep resistance were evaluated.

[0039] Comparative Example 2 The aramid fiber used as the sheath yarn in Example 1 was prepared, and the physical properties of this aramid fiber alone were evaluated. A 12-strand braided rope was prepared in the same manner as in Example 1, except that this aramid fiber was used instead of the composite covering yarn, and the tensile breaking elongation, tensile strength, and creep resistance were evaluated.

[0040] Comparative Example 3 Except for changing the twisting conditions of the sheath yarn to S110T / m, a composite covered yarn was produced in the same manner as in Example 1. The covering angle θ of the obtained composite covered yarn was 0.29 radians. The composite covering yarn was evaluated in the same manner as in Example 1. Furthermore, a 12-strand braided rope was produced in the same manner as in Example 1, and the tensile breaking elongation, tensile strength, and creep resistance were evaluated.

[0041] Comparative Example 4 Except for changing the twisting conditions of the sheath yarn to S550T / m, a composite covered yarn was produced in the same manner as in Example 1. The covering angle θ of the obtained composite covered yarn was 0.99 radians. The composite covering yarn was evaluated in the same manner as in Example 1. Furthermore, a 12-strand braided rope was produced in the same manner as in Example 1, and the tensile breaking elongation, tensile strength, and creep resistance were evaluated.

[0042] Comparative Example 5 A doubled and twisted yarn was obtained by giving a second twist of Z160T / m to the core yarn (polypropylene fiber, fineness 1100 dtex, number of fiber bundles: 2, twisting condition Z50T / m) used in Example 1 and the sheath yarn (Technora (registered trademark), manufactured by Teijin Limited, product number: T221 1100T / 667, number of fiber bundles: 1, twisting condition: S160T / m) used in Example 1. The covering angle θ of this doubled and twisted yarn was 0.41 radians. The produced ply-twisted yarn was evaluated in the same manner as in Example 1. Furthermore, a 12-strand braided rope was produced using this ply-twisted yarn in the same manner as in Example 1, and the tensile breaking elongation, tensile strength, and creep resistance were evaluated.

[0043] Comparative Example 6 The core yarn used in Example 1 (polypropylene fiber, fineness 1100 dtex, number of fiber bundles: 2, twisting condition Z50 T / m) and the sheath yarn used in Example 1 (Technora (registered trademark), manufactured by Teijin Limited, product number: T221 1100T / 667, number of fiber bundles: 1, number of single yarns in fiber bundle: 667, twisting condition: S160 T / m) were used to give a doubled and twisted yarn by giving a second twist of Z220 T / m. The covering angle θ of this doubled and twisted yarn was 0.54 radians. The prepared doubled and twisted yarn was evaluated in the same manner as in Example 1. A 12-strand braided rope was prepared using this doubled and twisted yarn in the same manner as in Example 1, and the tensile breaking elongation, tensile strength, and creep resistance were evaluated.

[0044] [Table 1]

[0045] [Table 2]

[0046] As shown in the evaluation results of Examples 1 and 2, it was confirmed that the composite covering yarn of the present invention has high elongation, high strength, low specific gravity and good creep properties. Regarding each fiber constituting the composite covering yarn, it was confirmed from Comparative Examples 1 and 2 that when polypropylene fiber was used alone, there was a problem with strength, and when aramid fiber was used alone, there were problems with elongation and specific gravity.

[0047] From Comparative Examples 3 and 4, in which the covering conditions of the sheath yarn were changed, it can be seen that the covering angle θ is important in order to achieve both tensile breaking elongation and tensile strength. That is, in Comparative Example 3, in which the covering angle θ is small, the strength of the composite covered yarn is maintained at a high level, but the tensile breaking elongation is low. Also, in Comparative Example 4, in which the covering angle θ is large, the tensile breaking elongation of the composite covered yarn is maintained at a high level, but the tensile strength is low. Therefore, in order to achieve both high levels of tensile breaking elongation and tensile strength, it is considered important to keep the composite covering angle θ within a certain range.

[0048] In Comparative Example 5, in which the compounding method was plying instead of covering, it was difficult to achieve high elongation with the ply-twisted yarn, although the covering angle was the same as in Example 1. This is thought to be because the polypropylene yarn and the aramid yarn mutually restrict each other's behavior during elongation due to the ply-twisted structure. Furthermore, in the case of Comparative Example 6, in which the twisting conditions were set to achieve the same tensile breaking elongation as in Example 1, it was confirmed that the tensile strength was not sufficiently maintained by increasing the twisting angle. [Industrial Applicability]

[0049] The composite covering yarn of the present invention can be used as a rope, in particular as a mooring rope. do.

Claims

[Claim 1] A mooring rope made of a composite covering yarn, which is made of a core yarn and a sheath yarn covering the core yarn, wherein the core yarn is made of a polypropylene fiber having a tensile breaking elongation of 15% or more, and the sheath yarn is made of a para-aromatic polyamide fiber having a tensile breaking elongation of 14% or less, the tensile breaking elongation being 9% or more, the tensile breaking strength being 8 cN / dtex or more, and the average specific gravity being 1.025 or less, and the covering angle θ calculated by the following formula being 0.30 to 0.41 radians. [0010] Where: θ: Covering angle (radian) D: Core yarn diameter (cm) d: Sheath thread diameter (cm) T: Number of sheath yarn twists (T / m)

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