WO2008097010A1

WO2008097010A1 - Composition and method for manufacturing high molecular composite reinforced fiber strength member of overhead electric cable

Info

Publication number: WO2008097010A1
Application number: PCT/KR2008/000702
Authority: WO
Inventors: Jae-Ik Lee; Jung-Hee Lee
Original assignee: Ls Cable, Ltd.
Priority date: 2007-02-05
Filing date: 2008-02-05
Publication date: 2008-08-14

Abstract

The present invention relates to a composite for manufacturing a fiber-reinforced polymer composite for a strength member of an overhead electric cable and a method for manufacturing a fiber-reinforced polymer composite for a strength member of an overhead electric cable using the same. The composite for manufacturing a fiber-reinforced polymer composite for a strength member of an overhead electric cable, provided in the present invention, comprises a thermosetting resin of an epoxy-based resin; a liquid curing agent of an acid anhydride-based or an amine-based compound; an accelerating agent of an imidazole-based compound or a boron- trifluoride ethylamine-based compound; a release agent of zinc stearate; and a filler of a nanoclay or a short glass fiber.

Description

COMPOSITION AND METHOD FOR MANUFACTURING HIGH

MOLECULAR COMPOSITE REINFORCED FIBER STRENGTH

MEMBER OF OVERHEAD ELECTRIC CABLE

Technical Field

[1] The present invention relates to a composition for manufacturing a fiber-reinforced polymer composite for a strength member of an overhead electric cable and a method for manufacturing a fiber-reinforced polymer composite for a strength member of an overhead electric cable using the same. In particular, the present invention relates to a composition for manufacturing a fiber-reinforced polymer composite for a strength member of an overhead electric cable, in which a thermosetting resin such as an epoxy resin is included in a high molecular resin composition, and an additive such as a curing agent or an accelerating agent is added with a proper amount, thereby improving high temperature characteristics to minimize a sagging phenomenon of the overhead electric cable, and to a method for manufacturing a fiber-reinforced polymer composite for a strength member of an overhead electric cable using the same. Background Art

[2] Generally, a conventional overhead electric cable has used an ACSR (Aluminum

Conductor Steel Reinforced) cable consisting of a stranded steel core designed to carry the transfer load, surrounded by one or more conductive layers of aluminum or an aluminum alloy. However, a thermal expansion coefficient of the stranded steel core increases in proportion to temperature, and thus the ACSR cable sags due to an increase of temperature related to an increase of ampacity, and consequently, the entire overhead electric cable sags. To prevent such a sagging phenomenon, steel towers are installed sufficiently high or the installation number of steel towers is increased to narrow an interval between the steel towers. However, these methods did not ultimately solve the problem, and may bring about another problem in an economical aspect.

[3] US Patent No. 6,796,365 teaches a composite for manufacturing an electrical cable, in which aluminum is included in a fiber-reinforced composite resin, however a thermal expansion coefficient of the composite is large, and accordingly, in the case that the composite is applied to an overhead electric cable, a sagging phenomenon occurs more severely than a polymer composite.

[4] Meanwhile, WO 03/091008 discloses combining fibers into a composite core of a large diameter rather than introducing a fiber-reinforced composite. However, physical properties such as tensile strength do not meet the requirements, and manufacturing equipment and process are complex to cause problem to commercialization. And, the composite core of a large diameter is not easy to store or convey.

[5] Therefore, the related industry has attempted to prevent or minimize a sagging phenomenon by improving properties of a strength member of an overhead electric cable, but the above-mentioned problem is still unsolved. The present invention was devised under this technical background. Disclosure of Invention Technical Problem

[6] An object of the present invention is to provide a composition for manufacturing a fiber-reinforced polymer composite for a strength member of an overhead electric cable, which reduces a sagging phenomenon and does not change properties, and a method for manufacturing a fiber-reinforced polymer composite for a strength member of an overhead electric cable using the same. Technical Solution

[7] According to an aspect of the present invention, a composition for manufacturing a fiber-reinforced polymer composite for a strength member of an overhead electric cable, comprises a thermosetting resin of an epoxy-based resin; a liquid curing agent of an acid anhydride-based compound or an amine-based compound; an accelerating agent of an imidazole-based compound or a borontrifluoride ethylamine-based compound; a release agent of zinc stearate; and a filler of a nanoclay or a short glass fiber.

[8] According to another aspect of the present invention, a composition for manufacturing a fiber-reinforced polymer composite for a strength member of an overhead electric cable, comprises a thermosetting resin of an ester-based resin or a polyimide- based resin; a release resin of zinc stearate; and a filler of a nanoclay or a short glass fiber.

[9] According to the present invention, a method for manufacturing a fiber-reinforced polymer composite for a strength member of an overhead electric cable, comprises (Sl) preparing a high strength fiber; (S2) surface-treating the prepared high strength fiber; (S3) completely drying the surface-treated high strength fiber in a vacuum oven; (S4) impregnating the surface-treated and dried high strength fiber with the above- mentioned composition for manufacturing a fiber-reinforced polymer composite for a strength member of an overhead electric cable; (S5) curing the composition permeated into the high strength fiber; and (S6) cooling the resultant. Mode for the Invention

[10] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to the description, it should be understood that the terms used in the specification and the appended claims should not be construed as limited to general and dictionary meanings, but interpreted based on the meanings and concepts corresponding to technical aspects of the present invention on the basis of the principle that the inventor is allowed to define terms appropriately for the best explanation. Therefore, the description proposed herein is just a preferable example for the purpose of illustrations only, not intended to limit the scope of the invention, so it should be understood that other equivalents and modifications could be made thereto without departing from the spirit and scope of the invention.

[11] The composition for manufacturing a fiber-reinforced polymer composite for a strength member of an overhead electric cable, provided in the present invention, comprises a thermosetting resin, a curing agent, an accelerating agent, a release agent and a filler.

[12] Preferably, the thermosetting resin is any one material selected from the group consisting of an epoxy-based resin, an ester-based resin and a polyimide-based resin. However, in the case that the ester-based resin or the polyimide-based resin selected as the thermosetting resin, a curing agent and an accelerating agent are not necessary.

[13] At this time, preferably, the epoxy-based resin selected as the thermosetting resin is a mixture of three kinds of epoxy resins including a diglycidyl ether bisphenol A epoxy resin, a polyfunctional epoxy resin with a content of 25 to 400 parts by weight based on weight of the diglycidyl ether bisphenol A epoxy resin, and a diglycidyl ether bisphenol F epoxy resin with a content of 5 to 25 parts by weight based on weight of the diglycidyl ether bisphenol A epoxy resin. At this time, more preferably, the polyfunctional epoxy resin is any one selected from the group consisting of a glycidyl amine-based polyfunctional epoxy resin and a novolak-based polyfunctional epoxy resin, or at least three polyfunctional epoxy resins, however the present invention is not limited in this regard.

[14] In the case that the ester-based resin is selected as the thermosetting resin, it is preferable to use a cyanate-based resin singularly. In the case that the polyimide-based resin is selected as the thermosetting resin, it is preferable to use an aromatic hetero cyclic polyimide resin or a bismaleide -based polyimide resin. In particular, it is more preferable to use the aromatic hetero cyclic polyimide resin in the form of induction to bisphenol A for easy molding, however the present invention is not limited in this regard.

[15] The diglycidyl ether bisphenol A epoxy resin may be represented as the following

Chemistry Figure 1.

[16] Chemistry Figure 1 Λ ^=X I 7=^

CH- -CH-CH₂- - 0 -^ _/>" ^C Λ_{\ /}/- 0CH₂ - CH- CH₂O- -

[17] The polyfunctional epoxy resin may be represented as the following Chemistry

Figure 2. [18] Chemistry Figure 2

[19] The diglycidyl ether bisphenol F epoxy resin may be represented as the following

Chemistry Figure 3. [20] ChemistryFigure 3

[21] Preferably, the curing agent is an acid anhydride-based compound or an amine- based compound, and the curing agent is liquid, however the present invention is not limited in this regard.

[22] At this time, the acid anhydride-based compound may be any one selected from the group consisting of methyl tetra hydro phthalic anhydride (MTHPA), tetra hydro phthalic anhydride (THPA), hexa hydro phthalic anhydride (HHPA) and nadic methyl anhydride (NMA), or mixtures thereof, however the present invention is not limited in this regard. Preferably, the acid anhydride-based compound has the content of 60 to 160 parts by weight based on weight of the epoxy-based resin. In the case that the content of the acid anhydride-based compound is less than the minimum, it is not preferable because heat resistance is reduced due to generation of unreacted epoxy when curing, and in the case that the content of the acid anhydride-based compound is more than the maximum, it is not preferable because heat resistance and properties are reduced due to a curing agent left after reaction with epoxy that acts as an impurity.

[23] The amine-based compound may be a cyclo aliphatic polyamine-based material or a fatty amine-based material, however the present invention is not limited in this regard. Preferably, the amine-based compound has a content of 15 to 60 parts by weight based on weight of the epoxy-based resin. The content range setting of the amine-based compound is made in the same context as that of the acid anhydride-based compound.

[24] Preferably, the cyclo aliphatic polyamine-based material is any one material selected from the group consisting of menthane diamine (MDA) and isophoronediamine (IPDA), however the present invention is not limited in this regard. Preferably, the fatty amine-based material is any one material selected from the group consisting of diaminodiphenyl sulfone (DDS) and diaminodiphenyl menthane (DDM), however the present invention is not limited in this regard.

[25] Preferably, in the case that the acid anhydride-based compound is used as the curing agent, the accelerating agent uses an imidazole-based compound, and in the case that the amine-based compound is used as the curing agent, the accelerating agent uses a boron trifluoride ethylamine-based compound.

[26] In the case that the imidazole-based compound is selected as the accelerating agent, preferably the imidazole-based compound has a content of 1 to 5 parts by weight based on weight of the epoxy-based resin. In the case that the content of the imidazole-based compound is less than the minimum, it is not preferable because a desired cure acceleration effect is not expected, and in the case that the content of the imidazole-based compound is more than the maximum, it is not preferable because a cure acceleration effect does not increase in proportion to an additional amount, and what is worse, an excessive amount of imidazole-based compound acts as an impurity to deteriorate the properties of a product.

[27] In the case that the boron trifluoride ethylamine-based compound is selected as the accelerating agent, preferably the content of the boron trifluoride ethylamine-based compound has a content of 2 to 10 parts by weight based on weight of the epoxy-based resin. The content range setting of the boron trifluoride ethylamine-based compound is made in the same context as that of the imidazole-based compound.

[28] Preferably, the release agent is zinc stearate, however the present invention is not limited in this regard. Meanwhile, preferably the zinc stearate selected as the release agent has a content of 1 to 5 parts by weight based on weight of the thermosetting resin. The release agent serves to reduce friction between a product and a molding die to facilitate workability. In the case that the content of the release agent is less than the minimum, it is not preferable because a release effect is not obtained, and in the case that the content of the release agent is more than the maximum, it is not preferable because a release effect does not increase in proportion to an additional amount, and what is worse, an excessive amount of zinc stearate acts as an impurity to deteriorate the properties of a product.

[29] Preferably, the filler is a nanoclay or a short glass fiber, however the present invention is not limited in this regard.

[30] In the case that the nanoclay is selected as the filler, preferably the nanoclay has a content of 1 to 5 parts by weight based on weight of the thermosetting resin, and more preferably, the nanoclay is in whisker or flake phase. In the case that the content of the nanoclay is less than the minimum, it is not preferable because a filling effect is not obtained, and in the case that the content of the nanoclay is more than the maximum, it is not preferable because a filling effect does not increase in proportion to an additional amount, and what is worse, an excessive amount of nanoclay acts as an impurity to deteriorate the properties of a product.

[31] In the case that the short glass fiber is selected as the filler, preferably the short glass fiber has a content of 5 to 30 parts by weight based on weight of the thermosetting resin, and more preferably, the short glass fiber is free of boron. In the case that the content of the filler is less than the minimum, it is not preferable because a filling effect is not obtained, and in the case that the content of the filler is more than the maximum, it is not preferable because a filling effect does not increase in proportion to an additional amount, and what is worse, an excessive amount of short glass fiber acts as an impurity to deteriorate the properties of a product.

[32] In order to achieve the above-mentioned objects of the present invention, the composition for manufacturing a fiber-reinforced polymer composite for a strength member of an overhead electric cable, provided in the present invention, is manufactured through the following steps (Sl) to (S6) in sequence.

[33] (Sl) Preparing a high strength fiber

[34] Preferably, the high strength fiber is a glass fiber, a carbon fiber, a PBO

(poly(p-phenylenebenzoxazole)) fiber, an aramid fiber, a basalt fiber and a carbon nano fiber, however the present invention is not limited in this regard.

[35] (S2) Surface-treating

[36] The surface-treating is performed using a coupling solution that is prepared by dissolving any one material selected from the group consisting of titanate, silane and zirconate in an isopropylalcohol (IPA) solution, and at this time, isopropylalcohol may be used 800 to 1,000 times as much as weight of the selected material, and the prepared high strength fiber is completely impregnated with the coupling solution and stirred for 30 minutes to 2 hours while maintaining the coupling solution between 70 and 8O⁰C. The surface-treating of the reinforced fiber using the coupling solution increases an interface adhesive strength between the high strength fiber and the thermosetting resin.

[37] (S3) Drying in a vacuum oven

[38] After the high strength fiber is surface-treated using the coupling solution by a wet method, the high strength fiber is sufficiently and completely dried in a vacuum oven of 100⁰C or more, and subsequently it is kept not to come in a direct contact with moisture.

[39] (S4) Impregnating with the composition

[40] Each component of the composition for manufacturing a fiber-reinforced polymer composite for a strength member of an overhead electric cable, prepared as mentioned above, is mixed, temperature is maintained between 40 and 6O⁰C to reduce viscosity of the composition, and the composition is uniformly mixed using a mechanical stirrer. At this time, a stirring speed is maintained to 100 rpm or more, and moisture in the thermosetting resin and bubbles occurring when stirring are removed by a vacuum pump during stirring. The prepared high strength fiber is impregnated with the above- mentioned composition.

[41] (S5) Curing of the composition

[42] After the impregnating step, heat and pressure or ultrasonic waves are applied to cure the composition permeated into the high strength fiber.

[43] (S6) Cooling

[44] The cured fiber-reinforced polymer composite is quickly cooled to produce a final product.

[45] The above-mentioned manufacturing steps (Sl) to (S6) may be performed by a single continuous system, for a specific example, a system for manufacturing a wire made of a high strength fiber-reinforced polymer composite. The manufacturing process is performed using a conventional system, and it is obvious that variation or modification may be made to the conventional system.

[46] The following Table 1 shows compositions manufactured in examples (1 to 6) and comparative examples (1 to 8), and overhead electric cables were manufactured using the compositions by the above-mentioned manufacturing method.

[47] Table 1

[48] In the above Table 1, resin A is a diglycidyl ether bisphenol A epoxy resin, resin B is a polyfunctional epoxy resin, resin C is a diglycidyl ether bisphenol F epoxy resin, resin D is a cyanate ester-based resin, resin E is an aromatic hetero cyclic polyimide resin, resin F is a bismaleide-based polyimide resin, resin G is a polypropylene resin that is a thermosetting resin, and resin H is an unsaturated polyester resin. Indication of O means a high strength fiber with surface treatment, and indication of x means a high strength fiber without surface treatment. The high strength fiber was PAN (polyacrylonitrile) based carbon fiber. The curing agent was methyl tetra hydro phthalic anhydride (MTHPA) of an acid anhydride -based compound, the accelerating agent was an imidazole-based compound, the release agent was zinc stearate, the filler was a nanoclay, and the short glass fiber was S-glass fiber free of boron.

[49] Each sample for evaluating properties was manufactured using the compositions of the examples (1 to 6) and comparative examples (1 to 8). The sample was tested by the following method in aspect of room temperature characteristics, high temperature characteristics, aging characteristics and bending characteristics.

[50] Evaluation of room temperature characteristics

[51] The room temperature characteristics were evaluated by measuring tensile strength

(Df/D), elongation (%) and modulus of elasticity (Df/D) of each sample while maintaining a tensile speed at 5D/min, and the results are shown in the following Table 2.

[52] Table 2

[53] As found through the above Table 2, the example 3 added a short glass fiber and showed a higher tensile strength than the other examples. The comparative examples 3, 4 and 6 used high strength fibers without surface treatment and showed unpreferable results, i.e. a lower tensile strength than the other comparative examples, and it is inferred that surface treatment of a high strength fiber influences the properties of a product. Generally, as a tensile strength should be 200 Df/D or more in consideration of an installation tension of an overhead electric cable and thermal decomposition and aging characteristics of a polymer material due to a long-term thermal exposure, the examples 1 to 6 have all good results over the standard level, and thus prove an effect of the present invention.

[54] Evaluation of high temperature characteristics

[55] The high temperature characteristics were evaluated by leaving each sample at a given temperature for 20 minutes, and measuring a tensile strength (Df/D) and a retention rate of tensile strength (%) of each sample at a given temperature while maintaining the tensile speed at 5 D/min, and the results are shown in the following Table 3.

[56] Table 3

[57] As a high temperature tensile strength should be 170 Df/D or more at 180 ⁰C in consideration of a long-term exposure of the overhead electric cable at a high temperature, the comparative examples 3, 5 and 6 used a relatively smaller content of a poly- functional resin than the examples (1 to 6), and showed a lower tensile strength related to a smaller heat resistance than the examples, and in particular, the comparative 3 has the same composition of epoxy as the example 1, but used a high strength fiber without surface treatment, and thus showed unpreferable results, i.e. a remarkably lower tensile strength than the example 1.

[58] Evaluation of aging characteristics

[59] The aging characteristics were evaluated by leaving each sample at a given temperature for 1,000 hours, and measuring a tensile strength (Df/D) and a retention rate of tensile strength (%) of each sample at room temperature while maintaining the tensile speed at 5 D/min, and the results are shown in the following Table 4.

[60] Table 4

[61] The aging tensile strength is a property for checking characteristics of a polymer material decomposed thermally in the case of a long-term exposure to a high temperature, and as the aging tensile strength should be 180 Df/D or more in the case of aging at 180 ⁰C for 1,000 hours, the comparative examples 3 and 4 used high strength fibers without surface treatment and showed a small tensile strength due to a weak interface adhesive strength between the high strength fiber and the epoxy in the case of a long-term exposure to a high temperature, the comparative examples 5 and 6 did not use a polyfunctional epoxy resin and showed a low heat resistance, and the comparative examples 7 and 8 used a polypropylene resin that is a thermosetting resin and an unsaturated polyester resin, having a low heat resistance, respectively, and showed unpreferable results, i.e. a low tensile strength.

[62] Evaluation of bending characteristics [63] The bending characteristics were evaluated using 4 point bending test by measuring a bending strength (Df/D) and a modulus of bending elasticity (%) of each sample while maintaining a measurement speed at 1.3 D/min, and the results are shown in the following Table 5.

[64] Table 5

[65] The bending strength is a property necessary to minimize the likelihood that an overhead electric cable may be bent due to wind, rain or snow when the overhead electric cable is installed up a steel tower, and the modulus of bending elasticity is a property for checking flexibility when the overhead electric cable is wound onto a bobbin and stored, and it is known that in the case that the modulus of bending elasticity is 4,500 or less, the overhead electric cable has preferable properties. The comparative example 3, 4 and 6 used a high strength fiber without surface treatment and showed a low bending strength, and the comparative examples 1 and 2 did not use a diglycidyl bisphenol F and showed unpreferable results, i.e. a high modulus of bending elasticity, and thus they are difficult to wind onto a bobbin.

[66] As shown in the Tables 2 to 5, the samples according to the examples (1 to 6) have better room temperature characteristics, high temperature characteristics, aging characteristics and bending characteristics than the samples according to the comparative examples (1 to 8).

[67] It should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. Industrial Applicability

[68] The present invention maintains high tensile characteristics at a high temperature and consequently stable thermal characteristics, and minimizes a sagging phenomenon, exhibits a sufficient mechanical strength, and allows for light weight to further minimize the sagging phenomenon. And, the present invention has the improved flexibility and thus can sufficiently withstand a normal force such as wind, snow or rain when laying a cable.

Claims

[1] A composition for manufacturing a high molecular composite reinforced fiber strength member of an overhead electric cable, comprising: a thermosetting resin of an epoxy-based resin; a liquid curing agent of an acid anhydride-based compound or an amine-based compound; an accelerating agent of an imidazole-based compound or a borontrifluoride ethylamine-based compound; a release agent of zinc stearate; and a filler of a nanoclay or a short glass fiber.

[2] The composition for manufacturing a high molecular composite reinforced fiber strength member of an overhead electric cable according to claim 1, wherein the epoxy-based resin selected as the thermosetting resin is a mixture of three kinds of epoxy resins including: a diglycidyl ether bisphenol A epoxy resin; a polyfunctional epoxy resin with a content of 25 to 400 parts by weight based on weight of the diglycidyl ether bisphenol A epoxy resin; and a diglycidyl ether bisphenol F epoxy resin with a content of 5 to 25 parts by weight based on weight of the diglycidyl ether bisphenol A epoxy resin.

[3] The composition for manufacturing a high molecular composite reinforced fiber strength member of an overhead electric cable according to claim 2, wherein the polyfunctional epoxy resin is any one or at least two polyfunctional epoxy resins selected from the group consisting of a glycidyl amine-based polyfunctional epoxy resin and a novolak-based polyfunctional epoxy resin.

[4] The composition for manufacturing a high molecular composite reinforced fiber strength member of an overhead electric cable according to claim 1, wherein the acid anhydride-based compound selected as the curing agent is any one selected from the group consisting of methyl tetra hydro phthalic anhydride (MTHPA), tetra hydro phthalic anhydride (THPA), hexa hydro phthalic anhydride (HHPA) and nadic methyl anhydride (NMA), or mixtures thereof, and has a content of 60 to 160 parts by weight based on weight of the epoxy-based resin.

[5] The composition for manufacturing a high molecular composite reinforced fiber strength member of an overhead electric cable according to claim 1, wherein the amine-based compound selected as the curing agent is a cyclo aliphatic polyamine-based material or a fatty amine-based material, and has a content of 15 to 60 parts by weight based on weight of the epoxy-based resin. [6] The composition for manufacturing a high molecular composite reinforced fiber strength member of an overhead electric cable according to claim 5, wherein the cyclo aliphatic polyamine-based material of the amine-based compound selected as the curing agent is any one material selected from the group consisting of menthane diamine (MDA) and isophoronediamine (IPDA), and wherein the fatty amine-based material selected as the curing agent is any one material selected from the group consisting of diaminodiphenyl sulfone (DDS) and diaminodiphenyl menthane (DDM).

[7] The composition for manufacturing a high molecular composite reinforced fiber strength member of an overhead electric cable according to claim 1, wherein the imidazole-based compound selected as the accelerating agent has a content of 1 to 5 parts by weight based on weight of the epoxy -based resin.

[8] The composition for manufacturing a high molecular composite reinforced fiber strength member of an overhead electric cable according to claim 1, wherein the borontrifluoride ethylamine-based compound selected as the accelerating agent has a content of 2 to 10 parts by weight based on weight of the epoxy -based resin.

[9] The composition for manufacturing a high molecular composite reinforced fiber strength member of an overhead electric cable according to claim 1, wherein the zinc stearate selected as the release agent has a content of 1 to 5 parts by weight based on weight of the thermosetting resin.

[10] The composition for manufacturing a high molecular composite reinforced fiber strength member of an overhead electric cable according to claim 1, wherein the nanoclay selected as the filler has a content of 1 to 5 parts by weight based on weight of the thermosetting resin, and wherein the short glass fiber selected as the filler has a content of 5 to 30 parts by weight based on weight of the thermosetting resin.

[11] A composition for manufacturing a high molecular composite reinforced fiber strength member of an overhead electric cable, comprising: a thermosetting resin of an ester-based resin or a polyimide-based resin; a release resin of zinc stearate; and a filler of a nanoclay or a short glass fiber.

[12] The composition for manufacturing a high molecular composite reinforced fiber strength member of an overhead electric cable according to claim 11, wherein the ester-based resin selected as the thermosetting resin is a cyanate ester-based resin, and wherein the polyimide-based resin selected as the thermosetting resin is a hetero cyclic polyimide resin. [13] The composition for manufacturing a high molecular composite reinforced fiber strength member of an overhead electric cable according to claim 11, wherein the zinc stearate selected as the release agent has a content of 1 to 5 parts by weight based on weight of the thermosetting resin. [14] The composition for manufacturing a high molecular composite reinforced fiber strength member of an overhead electric cable according to claim 11, wherein the nanoclay selected as the filler has a content of 1 to 5 parts by weight based on weight of the thermosetting resin, and wherein the short glass fiber selected as the filler has a content of 5 to 30 parts by weight based on weight of the thermosetting resin. [15] A method for manufacturing a high molecular composite reinforced fiber strength member of an overhead electric cable, comprising:

(51) preparing a high strength fiber;

(52) surface-treating the prepared high strength fiber;

(53) completely drying the surface-treated high strength fiber in a vacuum oven;

(54) impregnating the surface-treated and dried high strength fiber with the composition for manufacturing a high molecular composite reinforced fiber strength member of an overhead electric cable defined in any one of the claims 1 to 12;

(55) curing the composition permeated into the high strength fiber; and

(56) cooling the resultant.

[16] The method for manufacturing a high molecular composite reinforced fiber strength member of an overhead electric cable according to claim 15, wherein the high strength fiber of the step (Sl) is a glass fiber, a carbon fiber, a PBO (poly(p-phenylenebenzoxazole)) fiber, an aramid fiber, a basalt fiber or a carbon nano fiber.

[17] The method for manufacturing a high molecular composite reinforced fiber strength member of an overhead electric cable according to claim 15, wherein the surface-treating of the step (S2) is performed such that any one material selected from the group consisting of titanate, silane and zirconate is dissolved in an isopropylalcohol (IPA) solution of 800 and 1,000 times as much as weight of the selected material to prepare a coupling solution, and the high strength fiber is completely impregnated with the coupling solution while maintaining the coupling solution between 70 and 8O⁰C, and stirred for 30 minutes to 2 hours.