CN102516708B - Composite core for power grid transmission line wire and preparation method thereof - Google Patents

Abstract

The invention provides a composite core for a power grid transmission line wire and a preparation method thereof. The composite core has high strength, high toughness, high glass-transition temperature and surface cleanness. Materials of the composite core comprise a resin material and a strengthening material. The resin material comprises a thermosetting resin, a curing agent, an accelerating agent, a releasing agent, a flexibilizer and nanometer particles. The strengthening material is one kind or a plurality of kinds of carbon fiber, glass fiber, basalt fiber, boron fiber, aramid fiber, silicon carbonate fiber and protein bound iodine (PBI) fiber. The content of composite core fiber Vf=50-80%, tensile strength of the composite core is not lower than 2100MPa, and glass transition temperature of the composite core is not lower than 180 DEG C. The toughness of the composite core is remarkably improved, and breakage and cracking probability caused by brittleness factors in production, transportation and wire hanging construction processes are reduced.

Description

Composite core for power grid transmission line conductor and preparation method thereof

technical field

The invention belongs to the field of molding composite materials, that is, plastic materials containing reinforcing materials, fillers or preforms, and specifically relates to a composite core used for power grid transmission line conductors and a preparation method thereof.

Background technique

Steel-cored aluminum stranded wire is a reinforced wire with single-layer or multi-layer aluminum strands twisted outside the galvanized steel core wire. The laying of special geographical conditions such as valleys has the characteristics of good electrical conductivity, sufficient mechanical strength, high tensile strength, and the distance between towers and poles can be enlarged. Therefore, it is widely used in overhead transmission and distribution lines of various voltage levels.

Modern industry's increasing requirements for power supply reliability and power quality, as well as the gradual increase in power load demand, pose a more severe test to the power industry. The construction of power grid transmission lines is facing problems such as increasing shortage of land resources, scarcity of non-ferrous metal resources, rapid expansion of power transmission and environmental protection. At the end of the 20th century, people tried to use organic composite materials instead of metal materials to make the core material of the wire, and developed a new composite material synthetic core wire.

Comparing with the traditional ACSR, the composite core has the advantages of light weight, high strength, good thermal stability, low sag, large carrying capacity and corrosion resistance. It solves the problem of increasing the transmission capacity of power lines while making full use of existing iron towers, and avoids the technical problem of increasing the land use of line corridors as much as possible.

The development of composite cores abroad includes that Japan developed composite core conductors in the 1990s. The products are divided into two types: carbon fiber core aluminum stranded wire and heat-resistant carbon fiber core heat-resistant aluminum alloy stranded wire. The mass of the composite core is 1/5 of the conventional steel core, and the coefficient of linear expansion is about 1/12 of the steel core. Tests have proved that the tensile strength of the new composite material core conductor has been greatly improved, and the tensile curve characteristics at room temperature show elastic properties, that is, there is no plastic deformation when the material breaks, and the elongation after fracture is about 1.6%, which is not as plastic as steel core conductors.

The CTC company in the United States launched carbon fiber composite core aluminum stranded wire in 2003. The core wire is a single mandrel made of carbon fiber as the center layer and glass fiber covering. The carbon fiber is made of polyamide refractory treatment and carbonization; high strength , Epoxy resin with high toughness formula has strong impact resistance, resistance to tensile stress and bending stress. After the carbon fiber and glass fiber are pre-stretched, they are impregnated in epoxy resin, and then cured in a high-temperature mold to form a composite material core wire. The outer layer and adjacent outer layer of the core wire are aluminum wire strands with trapezoidal cross-section. Compared with traditional wires, this core wire has the advantages of light weight, high strength, low wire loss, and small sag, but its toughness is poor, and the composite core may crack due to brittle factors during production, transportation, and wire hanging construction. The probability of breakage poses a threat to the safety of power grid transmission line construction and operation.

The existing wires in China are all formed of metal wires or metal strips with good electrical conductivity, and the tensile strength of such wires is low. At the same time, due to the characteristics of metals, the wires made of metals will expand and contract severely with the change of ambient temperature, and are more prone to brittle fracture. In view of this, some people in China have begun to study carbon fiber composite aluminum cored wire, but there is no specific use parameter, and there is still a certain gap between research and development and production.

The inventor filed an application number of CN200910237469.6 in 2009, and an invention patent application titled "A Resin-based Composite Material Suitable for Power Transmission Line Expansion Conductors and Its Preparation Process", and its technical solution relates to an application for The preparation process for stable and continuous production of high-strength, high-temperature resistant, regular surface, and high-gloss composite cores solves the problems of long curing cycle, prone to mold blockage, lack of product surface finish, incomplete resin-coated fibers, and problems in existing preparation processes. The problems such as the decline of mechanical strength caused by the resin curing process, and the comprehensive performance of the product are improved, and the material consumption is saved. However, this patent application does not consider the issue of material toughness. When the composite material is used to prepare the composite core of the power grid transmission line, it is required that the composite core should not be cracked or broken due to brittle factors during the production, transportation and hanging construction process. Therefore, the toughness of the composite material Can not be ignored.

The application number is CN200910011099.4, and the invention patent application titled "glass fiber and carbon fiber composite core for transmission line conductors" discloses a glass fiber and carbon fiber composite core for transmission line conductors. The composite core is made of 50% to 50% carbon fibers 55%, glass fiber 10% to 15%, resin and auxiliary materials 30% to 40%. The composite core prepared by the application of the present invention has good tensile strength, but there is no raw material specially added to improve the toughness of the material in the preparation raw materials of the composite core, and only the tensile strength of the composite core is emphasized.

The tensile strength of the fiber-reinforced resin-based composite core can be well guaranteed, but due to the poor toughness of the fiber, how to effectively improve the toughness of the composite core while ensuring the comprehensive mechanical properties of the composite core is an urgent problem to be solved.

Contents of the invention

The object of the present invention is to provide a composite core used for power grid transmission line conductors and its preparation method. Under the premise of ensuring the tensile strength of the composite core, that is, the composite core fiber content V _f =50-80%, the composite core The tensile strength is not lower than 2100MPa, and the glass transition temperature of the composite core is not lower than 190°C; compared with ordinary composite cores, the toughness is increased by 20-50%, and the winding performance is improved from 55D, 2 turns, no cracking, to 30-30 45D, 2 turns, no cracking; and the surface of the composite core is smooth and the roughness is relatively low.

For realizing above-mentioned purpose of the invention, the technical scheme that the present invention takes is:

A composite core used for power grid transmission line conductors, the material for the composite core is made of resin material and fiber reinforcement material, the improvement is that in terms of volume fraction: the resin material is 20%-50%, the fiber Reinforcement material is 50-80%;

The resin material includes: 100 parts of thermosetting resin, 50-150 parts of curing agent, 1-20 parts of accelerator, 1-20 parts of release agent, 5-20 parts of toughening agent and 0.1-10 parts of nano particles.

Wherein: the fiber reinforcement material is one or more selected from carbon fiber, glass fiber, basalt fiber, boron fiber, aramid fiber, silicon carbide fiber or PBI fiber.

Wherein: the thermosetting resin is any one or more selected from phenolic resin, urea-formaldehyde resin, melamine-formaldehyde resin, epoxy resin, unsaturated resin, polyurethane or polyimide.

Wherein: the curing agent is one or more selected from acid anhydrides, aliphatic polyamines, alicyclic polyamines and aromatic polyamines.

Wherein: the accelerator accelerator is one or more selected from amines, phenols or imidazoles.

Wherein: the release agent is one or more selected from zinc stearate, stearic acid, silicone oil, silicone grease or self-made internal release agents.

Wherein: the toughening agent is selected from thermoplastic polyether polyol, polyethersulfone, polysulfone, polyether ether ketone, hyperbranched polyamide ester, liquid rubber, thermotropic liquid crystal polymer, polyester or several.

Wherein: the nanoparticles are one or more selected from nano-montmorillonite, nano-carbon fiber, nano-TiO ₂ , nano-SiO ₂ , BaTiO ₃ or nano-Al ₂ O ₃ .

A method for preparing a composite core as claimed in claim 1, wherein the improvement is that the steps of the method are as follows:

1) The uncoiled yarn bundle, that is, the fiber reinforced material, is dried and pretreated at 180-200°C for 1-2 minutes under the pulling force of the tractor, and then enters the impregnation tank after passing through the guide roller, the bundle grid plate and the yarn collection roller, and soaks the resin material The glue solution is 0.5-1h;

Among them, the temperature of the dipping tank is set at 40°C to 80°C;

2) The fiber reinforced material infiltrated by the resin material glue is preformed by discharging excess resin and air bubbles through a preforming mold with a certain interface shape;

The temperature in the preforming mold is 70°C to 120°C;

3) Curing molding:

The resin glue of the composite material is gradually heated up in the front-stage curing mold, and then formed and solidified after passing through the viscous fluid state, gel state, and glass state. Under the action of the internal release agent, it is pulled out by the traction device for demoulding;

Among them, the temperature of the first heating zone of the front curing mold is 120-180°C; the temperature of the second heating zone is 130-200°C; the temperature of the third heating zone is 140-190°C;

The post-curing molding of resin-based composite materials adopts four-stage continuous heating, and the temperature in the heating zone is 170-220°C;

Among them, the traction speed is not lower than 0.5m/min;

4) The product is rolled up by the wire take-up machine, and cut into a composite core of required length by a cutting device.

Owing to adopting above-mentioned technical scheme, compared with prior art, the beneficial effect of the present invention comprises:

1) The toughness of the composite core is significantly improved

The composite core obtained according to the preparation material and preparation process of the present invention is tested according to the winding performance of State Grid Corporation of China Enterprise Standard Q/GDW388-2009, and the performance index of the final carbon fiber composite core product should reach: compared with ordinary composite cores, The toughness is increased by 20-50%, that is, the winding performance is improved from 55D, 2 turns, no cracking, to 30-45D, 2 turns, no cracking, and the high toughness reduces the carbon fiber composite core during production, transportation and hanging construction. Fracture and cracking probability caused by brittle factors;

2) The tensile strength of the composite core is maintained at a certain level

Composite core fiber content Vf = 50-80%, composite core tensile strength not less than 2100MPa;

3) Using the DMA test method, the glass transition temperature of the composite core should not be lower than 180°C;

4) The preparation method is simple and easy to operate

The preparation method of the present invention rationally designs the specific parameters: traction speed, curing temperature and heating zone length, etc., and minimizes the preparation process, so that the preparation method of the composite core is simple, and the composite core molding speed is fast and the production efficiency is high.

Detailed ways

Below in conjunction with example the present invention is described in detail.

The invention discloses a resin formula and a preparation process of a carbon fiber composite core for a power grid transmission line conductor. The composite core has high strength, high toughness, high glass transition temperature and smooth surface. While maintaining the excellent comprehensive performance of the composite core, the invention significantly improves its toughness, and further reduces the fracture and cracking probability of the composite core caused by brittle factors during production, transportation and wire-hanging construction.

The resin system formulation of the high-toughness carbon fiber composite core preparation process of the present invention is: a thermosetting resin, a curing agent, an accelerator, a release agent, a toughening agent, and nanoparticles. Among them, the curing agent is one or more selected from acid anhydrides, aliphatic polyamines, alicyclic polyamines and aromatic polyamines; the accelerator is selected from one or more of amines, phenols, and imidazoles. one or more; the release agent is one or more selected from zinc stearate, stearic acid, silicone oil, silicone grease, self-made internal release agent; the toughening agent is selected from polyether polyol , polyethersulfone, polysulfone, polyether ether ketone, hyperbranched polyester amide, liquid rubber, thermotropic liquid crystal polymer, polyester or one or more; nanoparticles are selected from nano montmorillonite, nano One or more of carbon fiber, nano-TiO ₂ , nano-SiO ₂ , BaTiO ₃ or nano-Al ₂ O ₃ .

The resin formulation of the high-toughness composite core has the following ingredients: 100 parts of resin, 50-150 parts of curing agent, 1-20 parts of accelerator, 5-20 parts of toughening agent, 0.1-10 parts of nanoparticles, and release agent 1 to 20 copies.

The reinforcing fiber is one or more of carbon fiber, basalt fiber, glass fiber, boron fiber, aramid fiber, silicon carbide fiber, and PBI fiber.

Thermosetting resin refers to a large class of synthetic resins that undergo chemical reactions under heating, pressure, or under the action of curing agents and ultraviolet light, and cross-link and solidify into insoluble and infusible substances. , forming a network structure, so it has high rigidity, high hardness, high temperature resistance, non-flammability, and good dimensional stability of the product. Commonly used thermosetting resins include phenolic resin, urea-formaldehyde resin, melamine-formaldehyde resin, epoxy resin, butadiene resin, Unsaturated resin, polyurethane, polyimide, etc. The thermosetting resin in the present invention includes: epoxy resin, polyimide, butadiene resin and polyurethane. The epoxy resin can be one or more of glycidyl ethers, glycidyl esters, glycidyl amines, alicyclic epoxy compounds, and aromatic epoxy compounds. Among them, the glycidyl ethers can be bisphenol A (diphenol propane glycidyl ether), bisphenol F type epoxy resin, polyphenol type glycidyl ether epoxy resin, polyethylene glycol diglycidyl ether, polypropylene glycol diol One or more of glycidyl ether and 1,4-butanediol diglycidyl ether. Glycidyl esters can be one of diglycidyl phthalate, diglycidyl isophthalate, diglycidyl tetrahydrophthalate, diglycidyl hexahydrophthalate, or Several kinds. The alicyclic epoxy compound may be one or more of dicyclopentadiene dioxide, cyclohexenyl ester epoxy resin, and dicyclopentenyl ether dioxide. Glycidylamines can be one or more of 4,4'-diaminodiphenylmethane epoxy resin, p-aminophenol epoxy resin, melamine epoxy resin and hydantoin epoxy resin. The aromatic epoxy compound may be an aromatic polyether glycidyl ether epoxy resin, an aromatic hyperbranched polyester epoxy resin, or the like.

The reinforcing material is mainly used to increase the toughness and strength of the thermosetting resin. The classification of the reinforcing material is like wood powder, mineral powder, fiber or textiles. The reinforcing material of the present invention is selected from fiber, and the fiber is selected from carbon fiber, basalt fiber, glass fiber, boron arbitrarily. Fiber, aramid fiber, silicon carbide fiber, polybenzimidazole fiber or one or more; carbon fiber is made of polyacrylonitrile fiber, pitch fiber, viscose or phenolic fiber by carbonization; basalt fiber is basalt rock After melting at 1450 ° C ~ 1500 ° C, it is a continuous fiber drawn by a platinum-rhodium alloy drawing bushing at high speed; aramid fiber is poly-p-phenylene benzobisoxazole fiber, poly-p-phenylene benzobisthiazole One or more of fiber, polyether ether ketone fiber or polysulfone amide fiber.

The curing agent in the present invention is one or more selected from acid anhydrides, aliphatic polyamines, alicyclic polyamines and aromatic polyamines. The formula system used for acid anhydride curing agents has low viscosity and long service life. , can be divided into aromatic anhydrides, fatty acid anhydrides and halogenated anhydrides. The acid anhydride curing agent involved in the formula of the present invention can be 70 acid anhydride, which is a modified anhydride obtained by the reaction of butadiene and maleic anhydride; 80# flame-retardant liquid anhydride, which is a bromine-containing liquid anhydride , the cured product has self-extinguishing flame retardancy, excellent electrical properties, moisture resistance and physical and mechanical properties; 82 acid anhydride is tung oil anhydride obtained from tung oil modified maleic anhydride, which has internal plasticizing effect and can The mechanical properties and waterproof properties of the cured product are improved. The fatty polyamines can be ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, hexamethylenediamine, m-xylylenediamine and the like. The alicyclic polyamine curing agent can be menthane diamine, N-aminoethylpiperazine, isophorone diamine and the like. The aromatic polyamine curing agent can be m-xylylenediamine, m-phenylenediamine, diaminodiphenyl sulfone and the like.

Accelerator among the present invention is to be selected from one or more in amines, phenols, imidazoles arbitrarily; Accelerator one is as the curing agent of reinforcing resin, improves the hardness of rubber product; Additives such as diphenol together form the bonding system, which plays an important role in the bonding of rubber and fiber.

The release agent in the present invention is arbitrarily selected from one or more of zinc stearate, stearic acid, silicone oils, and silicone greases.

The toughening agent in the present invention is one or more selected from polyether polyol, polyether sulfone, polysulfone, polyether ether ketone, hyperbranched polyamide ester, liquid rubber, thermotropic liquid crystal polymer, polyester Species; thermoplastic resins such as polyethersulfone, polysulfone, and polyetheretherketone have the properties of softening by heating and hardening by cooling, and do not react chemically. No matter how many times heating and cooling are repeated, this property can be maintained. Thermoplastic resins The biggest advantage is that it is easy to process and shape, and has high mechanical energy. Hyperbranched polyamide has the advantages of low viscosity, high functionality, good solubility and no entanglement. Liquid rubber mainly refers to liquid nitrile rubber, liquid silicone rubber, etc. Thermotropic liquid crystal polymers are emerging after lyotropic liquid crystal polymers. They have excellent comprehensive properties and can be processed by injection molding and extrusion. Polyester is a general term for polymers obtained by polycondensation of polyols and polybasic acids. It mainly refers to polyethylene terephthalate (PET), and customarily also includes linear thermoplastic resins such as polybutylene terephthalate (PBT) and polyarylate. Polyarylate is a class of high-performance engineering plastics, mainly including polydiallyl terephthalate, polyparaben and U-polymer.

The nano particles in the present invention are one or more selected from nano-montmorillonite, nano-carbon fiber, nano-TiO ₂ , nano-SiO ₂ , BaTiO ₃ or nano-Al ₂ O ₃ . The addition of the nanoparticles and the toughening agent greatly improves the toughness of the composite material of the present invention. The addition of nanoparticles makes the composite material easy to absorb stress when receiving external force; the addition of toughening agent greatly improves the toughness of the resin system formulation, and the winding performance of the composite material is improved, thereby reducing the composite core during production, transportation and hanging. During the line construction process, the probability of cracking and fracture is caused by brittle factors.

The corresponding parameters corresponding to the preparation process of the novel high-toughness composite core described in the present invention are obtained on the following basis: taking the temperature field in the mold corresponding to the resin curing process involved in the composite core preparation process and the dynamic change of the resin curing degree as a reference, and taking The traction speed, curing temperature, and length of the heating zone are used as three factors, and heat resistance, tensile strength, and toughness are used as three levels for orthogonal design.

The invention provides a preparation process of a novel carbon fiber composite core for a high-toughness power grid transmission line conductor, comprising the following steps:

(1) The uncoiled yarn bundle (selected fiber) is dried at 180-200°C for 1 minute under the pulling force of the tractor, and after passing through a series of guide rollers, gathering grids and yarn collecting rollers, it enters the impregnating glue tank and is fully soaked The glue of the selected resin formula;

(2) The selected fiber is fully infiltrated by the nano-modified high-toughness resin formula glue, and the excess resin and air bubbles are discharged through a pre-forming mold with a certain interface shape for pre-forming;

(3) Curing molding: through the front-stage curing mold, the selected nano-modified high-toughness resin formula glue gradually heats up in the mold, and is molded and solidified after passing through the viscous fluid state, gel state, and glass state. The role of the internal release agent Next, it is pulled out by the traction device for demoulding;

(4) post-curing treatment;

(5) The product is rolled up by the wire take-up machine, and the product is cut into the required length by the cutting device.

Wherein, the temperature of the glue tank for impregnating the nano-modified high-toughness resin formulation system is constant at 40-80°C, and the temperature inside the preforming mold is 70-120°C.

Among them, the temperature of the first stage of the curing mold suitable for the nano-modified high-toughness resin formulation system is 120-180 °C; the temperature of the second heating area is 130-200 °C; the temperature of the third heating area is 140-190 °C.

Among them, the post-curing process suitable for the nano-modified high-toughness carbon fiber composite core adopts four-stage continuous heating, and the temperature in the heating interval is 170-220°C.

Among them, the traction speed is not lower than 0.5m/min.

The resin system formula and preparation process of the carbon fiber composite core for the wire of the grid transmission line according to the present invention are tested according to the winding performance of the enterprise standard Q/GDW388-2009 of the State Grid Corporation of China, and the performance index of the final carbon fiber composite core product should reach: and Compared with the ordinary composite core, the toughness is increased by 20-50% (the winding performance is improved from 55D, 2 turns, no cracking, to 30-45D, 2 turns, no cracking), the fiber content of the composite core V _f =50-80%, The tensile strength of the composite core is not lower than 2100MPa, and the glass transition temperature of the composite core is not lower than 190°C (using DMA test method).

Example 1

The resin formula involved in the preparation process of the novel high-toughness carbon fiber composite core of the present invention is according to the following ratio: 100 parts of thermosetting resin (glycidyl ether epoxy resin), 100 parts of curing agent (acid anhydride), accelerator ( Amines) 8 parts, nanoparticles (nano-montmorillonite) 5 parts, toughening agent (polyether polyols) 10 parts, mold release agent (stearic acid) 3 parts.

The temperature of the glue tank is constant at 60°C, and the temperature of the resin-infiltrated carbon fiber in the preheating zone at the front of the mold is 100°C.

The front-stage curing mold corresponding to the preparation process of the novel high-toughness composite core described in the present invention corresponds to a first heating zone of 160°C; a second heating zone of 180°C; and a third heating zone of 170°C. In the post-curing section, a four-stage continuous heating method is adopted, and the temperature in the heating section is 210°C.

Traction speed is set to 0.5m/min.

The samples prepared according to the above-mentioned new high-toughness composite core preparation process have been tested. The winding performance of the carbon fiber composite core is 42D, 2 turns, and the toughness of the composite core without cracking is increased by 24%. The glass transition temperature is 190°C and the tensile strength is 2257MPa.

Example 2

The resin formula involved in the preparation process of the novel high-toughness composite core according to the present invention is as follows: 100 parts of resin (glycidyl ether epoxy resin), 100 parts of curing agent (acid anhydrides), accelerator (amines) ) 12 parts, nanoparticles (nano SiO ₂ ) 3 parts, toughening agent (hyperbranched polyamide ester) 20 parts, mold release agent (stearic acid) 5 parts.

The temperature of the glue tank is constant at 60°C, and the temperature of the resin-infiltrated carbon fiber in the preheating zone at the front of the mold is 110°C.

The front-stage curing mold corresponding to the preparation process of the new high-toughness composite core described in the present invention corresponds to a first heating zone of 145°C; a second heating zone of 180°C; and a third heating zone of 175°C. In the post-curing section, a four-stage continuous heating method is adopted, and the temperature in the heating section is 220°C.

Traction speed is set to 0.6m/min.

The samples prepared according to the above-mentioned new high-toughness composite core preparation process were tested. The winding performance of the carbon fiber composite core was 38D, 2 turns, and the toughness of the composite core without cracking increased by 31%. The glass transition temperature was 198°C and the tensile strength was 2340MPa.

Example 3

The resin formula involved in the preparation process of the novel high-toughness composite core of the present invention is according to the following ratio: 100 parts of resin (aromatic polyether glycidyl ether epoxy resin), 110 parts of curing agent (acid anhydrides), accelerator (amines) 10 parts, nanoparticles (nanometer SiO ₂ ) 2 parts, toughening agent (polyether ether ketone) 18 parts, mold release agent (stearic acid) 5 parts.

The temperature of the glue tank is constant at 60°C, and the temperature of the resin-infiltrated carbon fiber in the preheating zone at the front of the mold is 110°C.

The front-stage curing mold corresponding to the preparation process of the novel high-toughness composite core described in the present invention corresponds to a first heating zone of 150°C; a second heating zone of 185°C; and a third heating zone of 170°C. In the post-curing section, a four-stage continuous heating method is adopted, and the temperature in the heating section is 200°C.

The traction speed is set to 0.55m/min.

The samples prepared according to the above-mentioned new high-toughness composite core preparation process have been tested. The carbon fiber composite core has a winding performance of 40D, 2 turns, no cracking, a 27% increase in toughness, a glass transition temperature of 195°C, and a tensile strength of 2308MPa.

The invention has been described herein in terms of specific exemplary embodiments. Appropriate substitutions or modifications will be apparent to those skilled in the art without departing from the scope of the present invention. The exemplary embodiments are illustrative only, and not limiting of the scope of the invention, which is defined by the appended claims.

Claims (5)

1. A composite core for power grid transmission line conductors, the material for the composite core is made of resin material and fiber reinforced material, characterized in that by volume fraction: the resin material is 20%-50%, fiber Reinforcement material is 50-80%; The resin material includes: 100 parts of thermosetting resin, 50-150 parts of curing agent, 1-20 parts of accelerator, 1-20 parts of release agent, 5-20 parts of toughening agent and 0.1-10 parts of nanoparticles; The release agent is one or more selected from zinc stearate, stearic acid, silicone oil, silicone grease or self-made internal release agents; The toughening agent is one or more selected from polyethersulfone, polysulfone, polyetheretherketone, hyperbranched polyesteramide, liquid rubber, thermotropic liquid crystal polymer, and polyester; The nanoparticles are one or more selected from nano-montmorillonite, nano-carbon fiber, nano-TiO ₂ , nano-SiO ₂ , BaTiO ₃ or nano-Al ₂ O ₃ ; The preparation method steps of the composite core are as follows: 1) The uncoiled yarn bundle, that is, the fiber reinforced material, is dried and pretreated at 180-200°C for 1-2 minutes under the pulling force of the tractor, and then enters the impregnation tank after passing through the guide roller, the gathering grid and the gathering roller, and soaks the resin material The glue solution is 0.5-1h; Among them, the temperature of the dipping tank is set at 40°C to 80°C; 2) The fiber reinforced material infiltrated by the resin material glue is preformed by discharging excess resin and air bubbles through a preforming mold with a certain interface shape; The temperature in the preforming mold is 70°C to 120°C; 3) Curing molding: The resin glue of the composite material is gradually heated up in the front-stage curing mold, and then formed and solidified after passing through the viscous fluid state, gel state, and glass state. Under the action of the internal release agent, it is pulled out by the traction device for demoulding; Among them, the temperature of the first heating zone of the front curing mold is 120-180°C; the temperature of the second heating zone is 130-200°C; the temperature of the third heating zone is 140-190°C; The post-curing molding of resin-based composite materials adopts four-stage continuous heating, and the temperature in the heating zone is 170-220°C; Among them, the traction speed is not lower than 0.5m/min; 4) The product is rolled by the wire take-up machine, and the composite core is cut into the required length by the cutting device. 2. The composite core for grid transmission line conductor as claimed in claim 1, characterized in that said fiber reinforced material is arbitrarily selected from carbon fiber, glass fiber, basalt fiber, boron fiber, aramid fiber, silicon carbide fiber or One or more of PBI fibers. 3. The composite core for grid transmission line conductor as claimed in claim 1, wherein said thermosetting resin is arbitrarily selected from phenolic resin, urea-formaldehyde resin, melamine-formaldehyde resin, epoxy resin, unsaturated resin, polyurethane Or one or more of polyimides. 4. The composite core for grid transmission line conductor as claimed in claim 1, characterized in that said curing agent is arbitrarily selected from acid anhydrides, aliphatic polyamines, alicyclic polyamines and aromatic polyamines one or several. 5. The composite core for power grid transmission line conductors according to claim 1, characterized in that the accelerator is one or more selected from amines, phenols or imidazoles.