RU2708846C1 - Production method of composite core of power transmission line - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to electrical engineering and can be used in production of multiwire wires for overhead lines intended for transmission of electric energy in overhead power lines and lines of electrified transport, in particular, in production of bearing cores in designs of cables and wires. Production method of composite core of power transmission line, including preparation of reinforcing fibers, uniform supply of reinforcing fibers into shaping draw plate, preparation of binder prepolymer, impregnation of reinforcing fibers with prepolymer under pressure, polymerization in shaping draw plate, ready product collection, differing by the fact that at the stage of preparing the binder system, the prepolymer is obtained by mixing the monomer solution ε-caprolactam and a catalyst with a solution of monomers ε-caprolactam and an activator, the reinforcing fiber impregnation is carried out with the obtained prepolymer, at the pultrusion step, as a result of anionic polymerization ε-caprolactam, a polymer matrix – caprolon is obtained.

EFFECT: technical result consists in improvement of strength characteristics of article and increase in speed of production due to increased rate of impregnating reinforcing fibers with binder.

14 cl, 2 tbl, 8 dwg

Description

Technical field

The invention relates to electrical engineering and can be used in the manufacture of multi-wire wires for overhead lines designed to transmit electrical energy in overhead electric networks and electrified transport lines, in particular, in the manufacture of bearing cores in the construction of cables and wires.

State of the art

The prior art technology of pultrusion to obtain composite materials with a constant cross section, including uninsulated wires with a composite core. The pultrusion technological process is continuous and, depending on the processes taking place, is divided into the following stages: preparation of the fiber and binder, impregnation, molding of the profile, curing of the binder (holding at a constant temperature), cooling to the final temperature, cutting the finished profile to size or winding onto a coil . The main advantage of pultrusion technology is the high speed of production of composite materials with a constant (uniform) quality of the products obtained.

In the traditional technology of pultrusion, various low-viscosity thermosetting binders (thermosets) of low molecular weight (epoxy, phenol-formaldehyde, organosilicon, polyester, etc.) that provide uniform impregnation of reinforcing fibers are almost always used as a polymer matrix (binder). So, the reinforcing fibers are mainly immersed in a container with a low-viscosity thermosetting binder, after which the excess binder is squeezed back into the container and the impregnated fibers are fed into a forming spinneret, where thermosetting takes place under the influence of temperature. The obtained thermoset materials have a number of drawbacks, especially significant in serial production: the inability to postprocess after polymerization, since they cease to soften when reheated and do not dissolve, but only swell, in solvents; fragility of the matrix after polymerization, in view of its high hardness; the complexity of anchoring (installation) of the finished product; difficulty in disposal; long production cycle; high cost of raw materials.

Recently, there has been 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 impact resistance; increased heat resistance; resistance to aggressive environments; unlimited long matrix viability; 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 re-heating it or processing it with a solvent. While the disadvantages manifested in the manufacture of composite materials from thermoplastic binders using pultrusion technology are the high viscosity of the binder, which complicates the process of impregnation of the reinforcing fibers and leads to the need to increase the pressure during the passage of the reinforcing fibers through the forming spinneret, 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 B32B 27/04 (2006.01), B05D 3/02 (2006.01), B05D 1/18 (2006.01), D04H 3/08 (2006.01), published on December 29, 2006, a method is known the manufacture of a composite core for an electric cable formed by a plurality of resin-impregnated reinforced fibers of at least one type, with the resin surrounding and substantially covering all reinforcing fibers that are oriented substantially 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 carrier core. In addition, various binders, including thermoplastic binders, are used as an impregnating resin in the method, and the problems described in the prior art are indicated in the “Prior art” description section, namely, when using carrier pultrusion technology thermoplastic core, firstly, does not have the required physical characteristics to effectively redistribute the load and prevent sagging of the cable, and secondly, does not correspond to the temperature conditions of the exp Luatation of cable products, thirdly, is limited in the maximum number of fibers used by the ratio of fiber to binder in the core, since the use of thermoplastic, as mentioned above, is hindered by its high viscosity, which, in turn, increases friction between the extrusion head (part dies) and moldable composite material. In this invention, page 13 shows two methods for using a thermoplastic binder, reducing the complexity of its use in pultrusion technology, in which the thermoplastic binder is present in solid form, and becomes liquid when heated at a later stage of the process. In the first method, a thermoplastic binder is present in the form of fibers that are intertwined with reinforcing fibers and, when heated in a die, impregnate reinforcing fibers. Moreover, the disadvantages of this method are insufficient impregnation of the fibers and the presence of voids in the resulting composite core. In the second method, it was proposed to cover each reinforcing thread with a layer of thermoplastic binder before being fed into the die and, also, to impregnate by heating the coated fibers in the die. Thus, the disadvantages of this method are the presence of voids in the resulting composite core and the complexity of the preliminary preparation of the reinforcing fibers coated with a thermoplastic resin. In other methods, including the preferred method in which an epoxy binder is used, thermoset binders are used, which are characterized by the above disadvantages.

From the RF patent for invention No. 2632454, IPC C08K 3/04 (2006.01), C08K 7/24 (2006.01), C08J 5/24 (2006.01), B32B 5/28 (2006.01), B32B 27/38 (2006.01), published 10/04/2017, there is a known method of manufacturing a composite core comprising carbon fiber or glass fiber. At the same time, the thermoplastic binder is used in it only as an additive to the epoxy binder, in the amount of from 5 to 20 wt.%. The advantage of the proposed solution is the use of the advantages of a thermoplastic binder. At the same time, the indicated solution is characterized by the disadvantages of thermoset binders.

The closest technical solution, selected as the closest analogue, is a method of manufacturing a composite core, known from international application PCT No. WO / 2009/130525, IPC B29C 70/52 (2006.01), H01B 5/10 (2006.01), published on 10.29.2009 g., with the help of which a composite core with a thermoplastic polymer matrix is manufactured using pultrusion technology. So, this method of manufacturing a composite core of a power line wire includes preparing reinforcing fibers, uniformly supplying reinforcing fibers to the forming die, preparing the binder prepolymer, impregnating the reinforcing fibers with the prepolymer under pressure, polymerizing in the forming die, collecting the finished product. The advantages of this method of manufacturing a composite core are manifested due to the use of a thermoplastic binder. Moreover, the disadvantage of this manufacturing method 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 laurillactam are melted and soaked in reinforcing fibers interwoven with them (carbon fibers and glass fibers), forming a polymer matrix as a result of anionic polymerization. The disadvantages of this method of obtaining a polymer matrix are insufficient impregnation of the reinforcing fibers and the presence of voids in the resulting composite core.

Disclosure of invention

The objective of the invention is to obtain a composite core consisting of reinforcing fibers and a thermoplastic binder (matrix) with the exception of defects in the impregnation of reinforcing fibers and voids in the resulting composite core.

The technical results achieved by the proposed production method consist in uniformly impregnating the reinforcing fibers with a binder with a uniform increase in pressure, which reduces the likelihood of voids and shells and disproportionate shrinkage, in obtaining a composite core with a high content of reinforcing fibers in volume and weight, which allows you to create products with high strength indicators, and in increasing the speed of the production process by increasing the speed of impregnation of reinforcing fibers with a binder, in the possibility of secondary processing of the composite core and the use of raw materials obtained from processing, as well as the possibility of local elimination of defects in the composite core.

The specified technical result is achieved using a method of manufacturing a composite core of a power line wire, including the preparation of reinforcing fibers, the uniform feeding of the reinforcing fibers into the forming die, the preparation of the binder prepolymer, the reinforcing fibers are impregnated with the prepolymer under pressure, the polymerization is carried out in the forming die, collecting the finished product. According to the stated solution, at the stage of preparation of the binder system, the prepolymer is prepared by displacing the solution of ε-caprolactam monomers and the catalyst with the solution of ε-caprolactam monomers and activator, the reinforcing fiber is impregnated with the obtained prepolymer, at the stage of pultrusion, as a result of the annionic polymerization of ε-caprolactam, get a polymer matrix - caprolon.

Advantageously, uniform feeding of unidirectional reinforcing fibers is carried out.

When reinforcing fibers are fed, they can form the inner part of the carbon fiber core and the outer part of the fiberglass core.

In addition, the weight percentage of fibers in the composite core is from 60 to 90%.

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

And as the activator can use acyl-derivatives of lactam (acetylcaprolactam) or compounds capable of acylating lactam under polymerization conditions.

In this case, the preparation of the binder can be carried out by obtaining a solution of ε-caprolactam monomers mixed with a catalyst at a temperature of from 70 to 90 ° C in an inert gas medium, and a solution of ε-caprolactam monomers mixed with an activator at a temperature of from 70 to 90 ° C inert gas environment.

Also, the preparation of the prepolymer by mixing a solution of ε-caprolactam monomers and a catalyst with a solution of ε-caprolactam monomers and an activator can be carried out at a temperature of from 110 to 140 ° C.

In addition, the reinforcing fibers can be impregnated with a binder by injection of the prepolymer into the forming die under a pressure of 3 to 5 Bar.

Pultrusion in the forming die can be carried out at a temperature of from 140 to 180 ° C

The forming zone of the die can have a channel taper angle of not more than 15 ° and not less than 5 ° to improve the quality and uniformity of impregnation and removal of air inclusions from the forming zone.

In addition, after polymerization of the matrix, the composite core can be subjected to smooth post-cooling in a snap up to 100 ° C in order to achieve uniform structure and eliminate internal stresses.

And after the polymerisation of the matrix, the composite core can be subjected to post-processing, including heating and molding according to the geometry, due to the special reinforcement of the wires.

The collection of the finished product can be carried out by winding the resulting composite core onto a coil or cutting the composite core to a predetermined length.

Unlike the closest analogue, in the above method, the reinforcing fiber is impregnated with a liquid low viscosity prepolymer and subsequent anionic polymerization is carried out with the formation of a thermoplastic polymer matrix consisting of caprolon.

Brief Description of the Drawings

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

The figure 1 shows the General layout of the line reactive thermoplastic pultrusion.

The figure 2 shows a General view of the die.

The figure 3 shows the scheme for the preparation of the prepolymer.

Figure 4 shows a General view of the broach module.

Figure 5 shows a General view of the slicing module.

Figure 6 shows a General view of the module for collecting fiber.

Figure 7 shows a cross section of a wire of a power line with a composite core.

The figure 8 shows a General view of the composite core.

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

Table 2 shows the nominal parameters and characteristics of composite cores.

The implementation of the invention

The present invention is illustrated by a specific method for the production of a composite core of a power line wire, however, the above example is not the only possible, but clearly demonstrate the possibility of achieving this set of essential features of the claimed technical result.

A method of manufacturing a composite core of a power line wire includes preparing reinforcing fibers. The preparation includes supplying unidirectional reinforcing fibers from the reinforcing fiber supply module 1, where the reinforcing fibers are wound from coils (not shown in the figures). The procedures for winding, leveling, tensioning and feeding carbon fiber and fiberglass are carried out in such a way as to ensure uniform distribution of the reinforcing fibers in the composite core.

Next, the reinforcing fibers are fed into the heating and drying module of the fiber 2, mainly consisting of a drying cabinet (not shown in the figures) with calibration plates (not shown in the figures), where the reinforcing fibers are passed through a drying cabinet to remove moisture and preheat. Each strand of reinforcing fibers passes through the holes of the calibration plates (not shown in the figures) to prevent tangling of individual rovings. Drying and heating of the fibers in an oven is carried out at a temperature of 180 ± 5 ° C.

After that, the reinforcing fibers are fed into the reinforcing fiber preparation module 3, where they are passed through preform gauges (not shown in the figures). Glass roving fibers pass through the gauge system along the outer contour so that at the entrance to the die (not shown in the figures) a uniform outer layer is formed that uniformly covers the central part of the core formed from carbon fiber.

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% of the mass of the composite core, while the lower value is due to the minimum strength characteristics, and the upper value is due to the possibility of impregnating the reinforcing fiber with an ε-caprolactam prepolymer .

The common fiber bundle thus formed is fed into the fiber forming module 4, where in the forming spinneret 5 the reinforcing fibers are impregnated with a prepolymer under pressure.

At the same time, in the preparation module of the binder system (not shown in the figure), a prepolymer is prepared, a schematic diagram of the preparation of the prepolymer is shown in figure 3. So, ε-caprolactam is dried to a moisture content of not more than 0.1%, and then melted in the melting tank 6 at a temperature of 70-90 ° C. You can dry ε-caprolactam in a vacuum drying oven (not shown in the figure) at a temperature of about 50 ° C or in a drying oven with air recirculation (not shown in the figure). The most rational drying in an inert gas environment. During the melting of 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 ε-caprolactam melt is not higher than 0.02%. From the melting tank 6, ε-caprolactam is fed into two separate mixing reactors: in the reactor 7 in the inert gas medium, the catalyst from the tank 8 is added to the solution, and in the second reactor 9 in the inert gas medium the activator from the tank 10 is used. Pipeline Nitrogen 11.

The preparation of the prepolymer in the binder system preparation module is carried out by mixing a solution of ε-caprolactam and sodium monomers with a solution of ε-caprolactam monomers and isocyanate. Moreover, 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% by weight of the composite core. A solution of ε-caprolactam with sodium and a solution of ε-caprolactam with isocyanate from mixers (reactor 7 and reactor 9) are fed to mixer 12. The required ratio of catalyst and activator is achieved by simultaneously supplying solutions through equal-cross-section channels. The prepolymer feed is controlled from the mixer 12 by the control unit 13. When the solutions are mixed, a prepolymer is formed, which enters the previously prepared and heated die 5. The polymerization is carried out directly in the die at a temperature of 140-180 ° C.

Instead of sodium, alkali and alkaline earth metals, their hydrides, amides, hydroxides, carbonates and their compounds, selected depending on the chosen activator of the polymerization process, can be used as a catalyst. Whereas instead of isocyanate, acyl derivatives of lactam (acetylcaprolactam) or compounds capable of acylating lactam under polymerization conditions, selected depending on the chosen catalyst of the polymerization process, as well as on the required density and degree of crystallinity of the polymer, can be used as activator. The catalyst and activator system is selected based on the required parameters of time, temperature and pressure of the following processes: preparing the prepolymer mixture, impregnating the reinforcing fibers with the prepolymer, and prepolymer polymerizing. The most complete polymerization takes place at an equivalent ratio of the components of the catalytic system, when one functional group of the activating compound falls on one functional group of the catalyst. 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% by weight of the composite core, which provides high-quality polymers.

The ε-caprolactam melt has a low viscosity of less than 1 Pa · s, which allows the reinforcing fibers to be impregnated.

After the reinforcing fiber is impregnated, the reinforcing fibers are further drawn through the forming die 5 (pultrusion), and, as a result of the annionic polymerization of the ε-caprolactam prepolymer, a caprolon polymer matrix is obtained.

Thus, during pultrusion, the following processes simultaneously occur in the die: impregnation of reinforcing fibers, polymer synthesis and the formation of a composite core, which depend on many factors: type of activator, polymerization mode, and cooling rate.

The reinforcing fibers are impregnated with a binder by injection of a prepolymer into a forming die under pressure from 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, passing from the shape and size of the channel of the input zone to the shape and size of the manufactured profile. Under these conditions, the molding pressure is created mainly by reducing the channel section along the length of the zone, due to the speed of drawing the material through the die and due to the excess amount of material entering the die. An important quantity characterizing the forming zone is the cone angle of the channel, which, on the one hand, should not exceed 15 °, so that the thermoplastic melt is captured by moving filler fibers, and on the other hand, should be of the minimum value to ensure a smooth increase in pressure, since this improves the quality and uniformity of impregnation over the thickness of the section and contributes to a more complete removal of air inclusions from the forming zone. However, too little 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 high temperature, and hence the degree of thermal degradation, and increases the binder outer surface.

The temperature of the prepolymer 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, mass and configuration of the core and should be in the range of 110-140 ° C. At lower temperatures, a polymer with a heterogeneous structure, a high content of low molecular weight compounds is formed, 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 exit and remain inside the core, and also there is no time for high-quality impregnation of reinforcing fibers, which causes the formation of numerous small pores, shrinkage shells and cracks.

The die temperature depends on the mass of the core. The lower temperature limit of the die is determined by the initial temperature of the prepolymer and should be above 150 ° C. At a lower temperature, a layer of unpolymerized monomer is formed 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 temperature of the polymer and is not higher than 180 ° C. At relatively low die temperatures, significant shrinkage shells and pores are formed.

The exposure time at the polymerization temperature is set based on the need to ensure the complete course of polymer solidification and depending on the polymerization rate, size and weight of the composite core.

The polymerization of ε-caprolactam in the presence of a catalyst and activator proceeds at a temperature below the melting point of the polymer and at atmospheric pressure.

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

After polymerization of the matrix, the composite core is subjected to post-processing, including heating and molding under special reinforcement of fastening and connecting wires.

The cooling mode affects not only the homogeneity of the structure, but also the internal stresses, which increase with increasing cooling rate. Therefore, the cooling rate should be adjusted depending on the mass of the composite core. Slow cooling of the composite core to 100 ° C, subsequent cooling in a thermostat (post-curing chamber, not shown in the figures) to 50 ° C and then in air seems to be the most optimal mode in terms of achieving the best characteristics of the composite core.

At the same time, during the processes of preparation and molding, the reinforcing fibers and then the resulting composite core are uniformly fed using the broaching module 14. Also, using the cutting module 15, the finished product is sliced. While the collection of the finished product is carried out using the module for collecting fiber 16.

After manufacturing, the composite core of the power line wire includes a central part 17 consisting of carbon fiber and a polymer matrix of caprolon, and an outer part 18 consisting of fiberglass and a polymer matrix of caprolon. After that, aluminum conductive wires 19 are wound onto the composite core.

Table 2 discloses the nominal parameters and characteristics of the resulting composite cores.

Claims (14)

1. A method of manufacturing a composite core of a power line wire, including the preparation of reinforcing fibers, the uniform feeding of the reinforcing fibers into the forming die, the preparation of the binder prepolymer, the impregnation of the reinforcing fibers with the prepolymer under pressure, the polymerization of the forming die, collecting the finished product, characterized in that at the stage of preparation of the binder system, the prepolymer is prepared by shifting the solution of ε-caprolactam monomers and the catalyst from creates monomers and ε-caprolactam activator, impregnating the reinforcing fiber is carried prepolymer obtained in step of pultrusion, resulting annionnoy polymerization of ε-caprolactam obtained polymer matrix - kaprolon. 2. A method of manufacturing a composite core of a power line wire according to claim 1, characterized in that the uniform supply of unidirectional reinforcing fibers. 3. A method of manufacturing a composite core of a power line wire according to claim 1, characterized in that when the reinforcing fibers are fed, the inner part of the carbon fiber core and the outer part of the fiberglass core are formed. 4. A method of manufacturing a composite core of a power line wire according to claim 1, characterized in that the weight percent of fibers in the composite core is from 60 to 90%. 5. A method of manufacturing a composite core of a power line wire according to claim 1, characterized in that alkali and alkaline earth metals, their hydrides, amides, hydroxides, carbonates and their compounds are used as a catalyst. 6. A method of manufacturing a composite core of a power line wire according to claim 1, characterized in that the activator uses acyl derivatives of lactam (acetylcaprolactam) or compounds capable of acylating lactam under polymerization conditions. 7. A method of manufacturing a composite core of a power line wire according to claim 1, characterized in that the preparation of the binder is carried out by obtaining a solution of ε-caprolactam monomers mixed with a catalyst at a temperature of from 70 to 90 ° C in an inert gas medium, and a solution of monomers ε- caprolactam mixed with an activator at a temperature of from 70 to 90 ° C in an inert gas environment. 8. A method of manufacturing a composite core of a power line wire according to claim 1, characterized in that the preparation of the prepolymer by mixing a solution of ε-caprolactam monomers and a catalyst with a solution of ε-caprolactam monomers and activator is carried out at a temperature of from 110 to 140 ° C. 9. A method of manufacturing a composite core of a power line wire according to claim 1, characterized in that the impregnation of the reinforcing fibers with a binder is carried out by injection of the prepolymer into the forming die under pressure from 3 to 5 bar. 10. A method of manufacturing a composite core of a power line wire according to claim 1, characterized in that pultrusion in the forming die is carried out at a temperature of from 140 to 180 ° C. 11. A method of manufacturing a composite core of a power line wire according to claim 1, characterized in that the forming zone of the die has a channel taper angle of not more than 15 ° and not less than 5 ° to improve the quality and uniformity of impregnation and removal of air inclusions from the forming zone. 12. A method of manufacturing a composite core of a power line wire according to claim 1, characterized in that after polymerization of the matrix, the composite core is subjected to smooth post-cooling in a snap up to 100 ° C. 13. A method of manufacturing a composite core of a 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 according to the geometry, due to the special reinforcement of the wires. 14. A method of manufacturing a composite core of a power line wire according to claim 1, characterized in that the collection of the finished product is carried out by winding the resulting composite core onto a coil or cutting the composite core to a predetermined length.

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