RU199200U1 - COMPOSITE POWER LINE CORE - Google Patents

Abstract

The utility model relates to electrical engineering and can be used in the construction of stranded wires for overhead lines, intended for the transmission of electrical energy in overhead power grids and lines of electrified transport as load-bearing cores in the structures of cables and wires. The technical results, which are manifested as a result of using the proposed composite core, are to increase the fracture toughness, crack resistance and post-shock strength, heat resistance, resistance to aggressive media, the viability of the matrix, the speed of technological cycles, as well as the possibility of recycling and local elimination of defects in the composite core. A composite core of a power line wire, made in the form of a rod made of a unidirectional composite material, including a central part consisting of carbon fiber and a polymer matrix, and an outer part consisting of glass fiber and a polymer matrix, while the polymer matrix consists of caprolon obtained as a result of anionic polymerization of a prepolymer mixture consisting of a solution of ε-caprolactam monomers and a catalyst and a solution of ε-caprolactam monomers and an activator.

Description

Technology area

The utility model relates to electrical engineering and can be used in the construction of stranded wires for overhead lines, intended for the transmission of electrical energy in overhead electrical networks and lines of electrified transport as load-bearing cores in the structures of cables and wires.

State of the art

Self-supporting bare wires are known from GOST 839-80, consisting of a steel core and aluminum conductive wires wound on it. The main disadvantages of these wires are high weight and low tensile strength compared to bare wires having a composite core made of carbon fibers.

Bare wires with composite cores pultruded to produce composite materials with a constant cross section are known in the art. The technological process of pultrusion is continuous and, depending on the ongoing processes, is divided into the following stages: fiber and binder preparation, impregnation, profile shaping, binder curing (holding at constant temperature), cooling to the final temperature, cutting the finished profile to size or winding onto a coil ... The main advantages of the pultrusion technology are the high speed of production of composite materials with a constant (uniform) quality of the resulting products.

In the traditional technology of pultrusion, various low-viscosity thermosetting binders (thermosetting plastics) of low molecular weight (epoxy, phenol-formaldehyde, organosilicon, polyester, etc.) are almost always used as a polymer matrix (binder), providing uniform impregnation of reinforcing fibers. So, reinforcing fibers are predominantly immersed in a container with a low-viscosity thermosetting binder, after which excess binder is squeezed back into the container and. the impregnated fibers are fed into a forming die, where thermoset polymerisation occurs under the influence of temperature. The obtained thermosetting materials have a number of disadvantages, which are especially significant during mass production: the impossibility of post-processing after polymerization, since they cease to soften upon reheating and do not dissolve, but only swell in solvents; fragility of the matrix after polymerization, due to its high hardness, the complexity of anchoring (mounting) of the finished product; difficulty in disposal; long production cycle time; high cost of raw materials.

Recently, there is a growing interest in the creation of reinforced plastics based on thermoplastic binders (thermoplastics). The main advantages of reinforced thermoplastics in comparison with polymer composite materials based on thermosetting binders: high fracture toughness, crack resistance and post-shock strength; increased heat resistance (compared to traditional epoxy resins); resistance to aggressive environments; unlimited long life of the matrix; high speeds of technological cycles; the possibility of secondary processing and local elimination of defects, the latter is possible due to the possibility of post-processing of the manufactured product by reheating it or treating it with a solvent. Whereas the disadvantages manifested when using thermoplastic binders in pultrusion technology are the high viscosity of the binder, which complicates the process of impregnating the reinforcing fibers, and leads to the need to increase the pressure during the passage of the reinforcing fibers through the forming die, as well as the possibility of uneven impregnation of the reinforcing fibers and the formation of products with defects.

From the Eurasian patent for invention No. 11625, IPC B32В 27/04 (2006.01), B05D 3/02 (2006.01), B05D 1/18 (2006.01), D04H 3/08 (2006.01), published on December 29, 2006, the composite a core for an electrical cable formed by a plurality of resin impregnated reinforced fibers of at least one type, the resin surrounding and substantially covering each of the plurality of reinforced fibers that are oriented generally parallel to the longitudinal axis of the core. Moreover, as indicated in the independent claim, the weight percentage of fibers in the composite is less than 50%, which is insufficient to achieve the load requirements of the required support core. In addition, various binders, including thermoplastic binders, are used as the impregnating resin, while the "Prior Art" section indicates the problems encountered by those skilled in the art, namely, a thermoplastic support core, firstly, it does not have the required physical characteristics for effective redistribution of the load and prevent cable sagging; secondly, it does not correspond to the temperature conditions of cable products operation; thirdly, it is limited in the maximum number of fibers used by the ratio of fiber and binder in the core, since the use of thermoplastic, as already mentioned above, it is hampered by its high viscosity, which, in turn, increases the friction between the extrusion head (part of the die) and the molded composite material. In this invention, on page 13, two methods of using a thermoplastic binder, which reduce the complexity of its use, are shown, in which the thermoplastic binder is present in solid form, and is transferred to a liquid state when heated at a later stage in the process. In the first embodiment, the thermoplastic binder is present in the form of fibers that are intertwined with reinforcing fibers and, heated in a die, impregnate the reinforcing fibers. In this case, the disadvantages of this option are insufficient fiber impregnation and the presence of voids in the resulting composite core. In the second variant, it was proposed to coat each reinforcing thread with a layer of thermoplastic binder before feeding into the die and, also, to carry out the impregnation by heating the coated fibers in the die. Thus, the disadvantages of this option are the presence of voids in the resulting composite core and the laboriousness of preliminary preparation of the reinforcing fibers coated with a thermoplastic resin. In other embodiments, including the preferred embodiment in which an epoxy binder is used, thermosetting binders are used, which have the above disadvantages.

From RF patent for invention No. 2632454, IPC С08K 3/04 (2006.01), С08K 7/24 (2006.01), C08J 5/24 (2006.01), В32В 5/28 (2006.01), В32B 27/38 (2006.01), published 10/04/2017, a composite core is known using carbon fiber or glass fiber. In this case, a thermoplastic binder is used in it only as an additive to an epoxy binder, in the amount of 5 to 20 wt. %. The advantage of the proposed solution is the use of the advantages of a thermoplastic binder. In this case, the specified solution is characterized by the disadvantages of thermosetting binders.

The closest technical solution, chosen as the closest analogue, is a composite core known from the international PCT application No. WO / 2009/130525, IPC В29С 70/52 (2006.01), H01В 5/10 (2006.01), published on October 29, 2009 , manufactured using pultrusion technology using a thermoplastic polymer matrix. Thus, the composite core of the power line wire is made in the form of a rod made of a unidirectional composite material, including a central part consisting of carbon fiber and a thermoplastic polymer matrix, and

an outer part consisting of fiberglass and a thermoplastic polymer matrix. The advantages of this design appear due to the use of a thermoplastic binder. Also, the advantage of this design is the absence of electrical contact between the carbon reinforcing core and aluminum conductive wires, interrupted by the outer part consisting of glass fiber and thermoplastic polymer matrix, which excludes electrochemical corrosion processes. In this case, the disadvantage of this solution is manifested as a result of the use of thermoplastic fibers in solid form for weaving and further impregnation of reinforcing fibers. As indicated in example No. 3, thermoplastic fibers selected from carpolactam and lauryl lactam, being heated in a forming die, melt and impregnate the reinforcing fibers (carbon fibers and glass fibers) intertwined with them, with the formation of a polymer matrix as a result of anionic polymerization. The disadvantages of this method for producing a polymer matrix are insufficient impregnation of the reinforcing fibers and the presence of voids in the resulting composite core, as well as a relatively low content of reinforcing fibers. Disclosure of a utility model

The task of the utility model is to obtain a composite core consisting of reinforcing fibers and a thermoplastic binder (matrix) with the exclusion of impregnation defects of reinforcing fibers and voids in the resulting composite core.

The technical results, which are manifested as a result of using the proposed composite core, are to increase the fracture toughness, crack resistance and post-shock strength, heat resistance, resistance to aggressive media, the viability of the matrix, the speed of technological cycles, as well as the possibility of recycling and local elimination of defects in the composite core.

The specified technical result is achieved using a composite core of a power line wire made in the form of a rod made of a unidirectional composite material, including a central part consisting of carbon fiber and a polymer matrix, and an external part consisting of glass fiber and a polymer matrix. According to the claimed solution, the polymer matrix consists of caprolone, obtained as a result of anionic polymerization of a prepolymer mixture consisting of a solution of ε-caprolactam monomers and a catalyst, and a solution of ε-caprolactam monomers and an activator.

In this case, alkali and alkaline earth metals, their hydrides, amides, hydroxides, carbonates and their compounds can be used as a catalyst.

As an activator, acyl derivatives of lactam (acetyl caprolactam) or compounds capable of acylating lactam under polymerization conditions can be used.

In addition, the weight percentage of fibers in the composite core is at least 60%.

The predominantly composite core of the power line wire is made by reactive thermoplastic pultrusion.

In addition, after polymerization of the matrix, the composite core can be subjected to post-processing, including heating and molding for special reinforcement for fastening and connecting wires.

In contrast to the closest analogue, the binder of the proposed composite core of the power line wire allows to completely impregnate the reinforcing fibers and obtain, as a result of anionic polymerization, a thermoplastic polymer matrix consisting of caprolon.

Brief Description of Drawings

The essence of the claimed utility model and the possibility of its practical implementation is illustrated by the description below, figures and tables.

Figure 1 shows a cross-sectional view of a composite core power line wire.

Figure 2 shows a general view of a composite core.

Table 1 shows the minimum physical and mechanical properties of the composite core.

Table 2 shows the ratings and characteristics of the composite cores.

Implementation of the utility model

The proposed utility model is illustrated by the specific design of the composite core of the transmission line wire, however, the given example is not the only possible one, but clearly demonstrates the possibility of achieving by this set, essential features of the claimed technical result. The composite core of the power line wire is made in the form of a rod made of a unidirectional composite material, including the central part 1, consisting of carbon fiber and a polymer matrix, and an outer part 2, consisting of glass fiber and a polymer matrix, while the polymer matrix consists of caprolon obtained as a result anionic polymerization of a prepolymer mixture consisting of a solution of ε-caprolactam and sodium monomers and a solution of ε-caprolactam and isocyanate monomers. In this case, the content of ε-caprolactam is 19.6% of the mass. composite core, the sodium content is 0.2% of the mass. composite core, and the isocyanate content is 0.2% of the mass. composite core.

Instead of sodium, alkali and alkaline earth metals, their hydrides, amides, hydroxides, carbonates and their compounds, selected depending on the selected activator of the polymerization process, can be used as a catalyst. Whereas, instead of isocyanate, α-acyl derivatives of lactam (acetyl caprolactam) or compounds capable of acylating lactam under polymerization conditions, selected depending on the selected catalyst of the polymerization process, as well as on the required density and degree of crystallinity of the polymer, can be used as an activator. The system of catalyst and activator is selected based on the required parameters of time, temperature and pressure of the following processes: preparation of a prepolymer mixture, impregnation of reinforcing fibers with a perpolymer, polymerization of the prepolymer. The most complete polymerization takes place with an equivalent ratio of the components of the catalytic system, when one functional group of the catalyst has one functional group of the activating compound. An increase in the molar concentration of one of the components either slows down or completely stops the polymerization process. The optimum concentration of the catalytic system is from 0.3 to 0.5 wt% of the composite core, which ensures the production of high quality polymers. The weight percentage of fibers in the composite core is 80%. To achieve the minimum physical and mechanical characteristics shown in Table 1, the fiber content is selected from 60 to 90% by weight of the composite core, while the lower value is due to the minimum strength characteristics, and the upper value is due to the possibilities of impregnation of the reinforcing fiber with a prepolymer based on ε-caprolactam ...

The composite core of the power line wire is made by the method of reactive thermoplastic pultrusion, in which, in the process of pultrusion, the prepolymer, consisting of a solution of ε-caprolactam and a catalyst and a solution of ε-caprolactam and an activator, is polymerized to form a thermoplastic matrix.

The process of obtaining a composite core consists of the following stages: preparation of raw materials, preparation of a solution of ε-caprolactam with a catalyst and a solution of ε-caprolactam with an activator, preparation of a prepolymer, and molding of a composite core.

Preparation of raw materials

ε-caprolactam is dried to a moisture content of not more than 0.1%, and then melted in a melting tank (not shown in the figures) at a temperature of 70-90 ° C. It is possible to dry ε-caprolactam in a vacuum drying cabinet at a temperature of about 50 ° C or in a drying cabinet with air recirculation. Drying in an inert gas environment is most rational.

In the process of melting ε-caprolactam, residual moisture is removed from it under a pressure of 0.02 MPa of inert gas supplied to the melting tank. The permissible final moisture content of the caprolactam melt is not higher than 0.02%.

Coiling, alignment, tensioning and feeding of carbon and glass fibers are carried out in such a way as to ensure an even distribution of the reinforcing fibers in the composite core. The reinforcing fibers are then passed through an oven (not shown in the figures) to remove moisture and preheat. Each bundle of reinforcing fibers passes through the holes of the sizing plates (not shown in the figures) to avoid tangling of individual rovings. Drying and heating of fibers in a drying oven is carried out at a temperature of 180 ± 5 ° C. Next, the reinforcing fibers are passed through preforming gauges (not shown in the figures). Fibers of glass roving pass through the gauge system along the outer contour so that a uniform outer layer is formed at the entrance to the die (not shown in the figures), which uniformly covers the central part of the core formed from carbon fiber. The total fiber bundle thus formed enters the die.

Preparation of solutions

From the melter, ε-caprolactam is fed into two separate mixing reactors (not shown in the figures): in the first reactor, a catalyst is added to the solution, and in the second, an activator.

When mixing ε-caprolactam with a catalyst, the temperature should not exceed 120 ° C. The mixing temperature of ε-caprolactam with the activator can vary from 120 ° C to 140 ° C.

Preparation of prepolymer

A solution of ε-caprolactam with a catalyst and a solution of ε-caprolactam with an activator from the mixers enter the mixer (not shown in the figure). The required ratio of catalyst and activator is achieved by the simultaneous supply of solutions through channels of equal cross-section. When the solutions are mixed, a prepolymer is formed, which enters a previously prepared and heated die. Polymerization is carried out directly in the die at a temperature of 140 - 180 ° C.

Composite core molding

The ε-caprolactam melt has a low viscosity of less than 1 Pa⋅s, which makes it possible to impregnate reinforcing fibers.

So, in the spinneret, the following processes take place simultaneously: impregnation of reinforcing fibers, polymer synthesis. and the formation-] of a composite core, which depend on many factors: type of activator, polymerization mode, cooling rate.

Impregnation of the reinforcing fibers with a binder is carried out by injecting the prepolymer into the forming die at a pressure of 3 to 5 bar.

The forming zone of the die has a channel taper angle of 12 °. The forming zone of the die has a tapering channel, changing from the shape and dimensions of the channel, the inlet zone to the shape and dimensions of the profile being produced. Under these conditions, the forming pressure is created mainly due to a decrease in the channel cross-section along the length of the zone, due to the speed of pulling the material through the die and due to the excess amount of material entering the die. An important value that characterizes the forming zone is the taper angle of the channel, which, on the one hand, should not exceed 15 ° so that the thermoplastic melt is captured by the moving filler fibers, and on the other hand, should have a minimum value to ensure a smooth increase in pressure, since this improves the quality and uniformity of impregnation over the section thickness and promotes more complete removal of air inclusions from the forming zone. However, too small a taper (less than 5 °) leads to an unjustified increase in the length of this zone, and hence the dimensions of the entire die, which, in turn, increases the residence time of the melt at a high temperature, and hence the degree of thermal destruction, and increases the extraction of the binder with outer surface.

The prepolymer temperature significantly affects the entire course of the polymer production process, as well as the properties and quality of the finished composite core. The temperature of the prepolymer depends on the activator, weight and configuration of the core and should be within 120 - 140 ° C. At lower temperatures, a polymer with an inhomogeneous structure is formed, with a high content of low molecular weight compounds, and, therefore, the quality of the core will be low. At temperatures above 140 ° C, the polymerization reaction proceeds at a high speed, and the viscosity of the prepolymer increases rapidly, as a result of which air and volatile components do not have time to completely escape and remain inside the core, and also does not have time to achieve high-quality impregnation of reinforcing fibers, which is the reason for the formation of numerous small pores, shrinkage cavities and cracks.

The die temperature depends on the mass of the core. The lower limit of the temperature of the die is determined by the initial temperature of the prepolymer and must be above 150 ° C. At a lower temperature, a layer of non-polymerized monomer will form on the surface of the composite core, and the polymer will have reduced strength characteristics. The upper limit of the die temperature is set so that the final maximum temperature of structure formation does not exceed the melting point of the polymer and does not exceed 180 ° C. At relatively low die temperatures, significant shrinkage cavities and pores are formed.

The holding time at the polymerization temperature is set based on the need to ensure the full course of polymer solidification processes and depending on the polymerization rate, the dimensions and weight of the composite core.

A characteristic feature of the process of anionic polymerization of ε-caprolactam is that it proceeds at a temperature below the melting point of the polymer, due to which the processes of macromolecule growth and their ordering (crystallization) are partially superimposed on each other. The cooling rate has a great influence on the formation of the structure, and upon slow cooling, polymers with a homogeneous structure, good surface, and high physical and mechanical characteristics are obtained.

The cooling mode affects not only the homogeneity of the structure, but also the internal stresses, which increase with an increase in the cooling rate. Therefore, the cooling rate must be controlled depending on the weight of the composite core. Slow cooling of the composite core to 100 ° С, subsequent cooling in a thermostat (post-curing chamber, not shown in the figures) to 50 ° С and then in air seems to be the most optimal mode in terms of achieving the best characteristics of the composite core. After polymerization of the matrix, the composite core is subjected to post-processing, which includes heating and molding for special reinforcement for strengthening and connecting wires.

After that, aluminum conductive wires 3 are wound on the composite core.

Table 2 discloses the ratings and characteristics of the resulting composite cores.

Claims (6)

1. A composite core of a power line wire made in the form of a rod made of a unidirectional composite material, including a central part consisting of carbon fiber and a polymer matrix, and an outer part consisting of glass fiber and a polymer matrix, characterized in that the polymer matrix consists of caprolon, obtained as a result of anionic polymerization of a prepolymer mixture consisting of a solution of ε-caprolactam monomers and a catalyst and a solution of ε-caprolactam monomers and an activator. 2. A composite core of a power transmission line wire according to claim 1, characterized in that alkali and alkaline earth metals, their hydrides, amides, hydroxides, carbonates and other compounds can be used as a catalyst. 3. The composite core of a power transmission line wire according to claim 1, characterized in that the activator can be -acyl-derivatives of lactam (acetyl caprolactam) or compounds capable of acylating lactam under polymerization conditions. 4. The composite core of the power line wire according to claim 1, wherein the weight percentage of fibers in the composite core is at least 60%. 5. The composite core of the power line wire according to claim 1, characterized in that it is made by the method of reactive thermoplastic pultrusion. 6. The composite core of the power line wire according to claim 1, characterized in that after polymerization of the matrix, the composite core is subjected to post-processing, including heating and molding for special reinforcement for fastening and connecting wires.

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