Electric cable, comprising insulation from foamed polyolefine, and method of its manufacturing

FIELD: power engineering.

SUBSTANCE: method is described for manufacturing of electric cable (10), comprising at least one core, which includes conductor (1) and insulating coating (2), which surrounds conductor, at the same time method includes the following stages: supply of polyolefine material, cross-linking system on silane basis and foam generation system, comprising at least one exothermic foaming agent in amount of at least 0.1% - 0.5% (wt) per total mass of polyolefine material; production of polyolefine material mixture, cross-linking system on silane basis and foam generation system; and extrusion of mixture to conductor (1) to make insulating coating (2). Also electric (10) is described, which comprises at least one core, which consists of conductor (1) and insulating coating (2), which surrounds mentioned conductor (1) and is in contact with it, at the same time insulating coat (2) mainly consists of a layer of foamed silane-linked polyolefine material, characterised with extent of foaming in the range from 3% to 40%.

EFFECT: increased flexibility of cable, improved mechanical characteristics and electric properties.

55 cl, 6 tbl, 6 ex

 

The technical field

The present invention relates to an electrical cable.

In addition, the present invention relates to a method of manufacturing the aforementioned electric cable.

The level of technology

In General, cables for electric power transmission and supply metal conductor, which is surrounded by an insulating coating.

Power cable can be provided to the shell at the position of the outer radial location relative to the insulating layer. The said shell is provided to protect the cable from mechanical damage.

The document US 4789589 relates to insulated electric wire conductor, where the insulation surrounding the guidewire includes an inner layer formed from a polyolefin mixture and having a cellular structure, and an outer layer formed from uncured and poterjannogo polyvinyl chloride.

Document WO 03/088274 relates to a cable having an insulating coating comprising at least two insulating layers so that in the radial direction from the inside of the cable to the outside of the insulating coating is comprised of at least one insulating layer formed from newspring polymer material, and at least one insulating layer formed from a foamed polymeric material. The fact is Cesky foamed insulating layer shows the presence of discontinuities (i.e. voids in the polymer material, these air-filled cavities or gas) and would not be able to properly function in the space surrounding the conductor, where the highest value is the electric field.

As reported, for example, in the document US 4591606, stitched penopoliuretan receive as a result of the use of chemical foaming agents, such as azodicarbonamide, which decompose when heated and emit gaseous nitrogen. Stitching is usually achieved with the help of initiator radicals, such as dicumylperoxide. Passing the reaction stitching also achieve by heating. Were also developed and methods of making cross-linked polyethylene, but in this case, the stapling is performed through irradiation. The products of this method are characterized by very low densities, so you cannot include any applications that require strength and stiffness. In the case of use as a staple organic peroxide regulation in the way is difficult, because the processes of both foaming and crosslinking are temperature dependent.

The document US 3098831 relates to crosslinked and foamed plastic material, suitable for use, inter alia, as electrical insulation. Mentioned plastic material, it is reported to, characterized by a density of not greater 0.32 g/cm3(20 pounds per cubic foot). Examples using polyethylene characterized by the degree of foaming of 90-95%. Polyethylene foam receive feedback on cross-linked polyethylene containing rubber foam, high temperature at which the blowing agent decomposes and thus raises the polyethylene foaming. The original plastic material can be made, for example, by using an organic peroxide, in General, the amount of binder ranges from 0.002 to 0.01 mol per 100 grams of polyethylene. Among the blowing agents in the example of azodicarbonamide, and per 100 parts of polyethylene material used approximately from 2 to 15 mass parts of foaming agent.

In the General case, the cable for cabling in the building and/or industrial applications must be laid inside the walls, and the method of installation requires a cable through a constriction in the walls or, more often, the pulling of cable through the conduit where the cable is subjected to continuous compression.

The proper styling with simple and fast operations, the cable must be particularly flexible, so that it can be inserted into the passages in the wall is e and/or wall of the conduit and no damage would bend route installation.

In General, the progress made by the user laying cables for cabling in the building due to the sinuosity of the route of the styling and appearance of friction during the operation of broaching are breaks or scrapes on the rough edges and/or surfaces.

Increasing the flexibility of the electrical cable may allow you to reduce damage due to mentioned tearing or scraping action. As described, for example, in the previously mentioned document WO 03/088274, the flexible cable can best increase in the supply cable foamed insulating layer that will allow you to achieve excellent results in the process of its installation.

Increased flexibility of the foam insulating layer may be made due to the "spongy" the nature of the material. In particular, the flexibility of the cable can be increased to a maximum when the insulating layer will consist of a layer of foamed material.

In addition, the cable foamed coating reduces the weight of the cable, which achieves the advantages at its transportation and installation.

However, the foam insulating layer may cause problems, such as:

- when in contact with the conductor discontinuity in the foamed material could the s impair the insulating properties of the layer;

- foamed insulating material coating shall have a minimum degree of foaming, high enough to impart the desired flexibility, but not so that in the wrong degree would weaken the coating from mechanical point of view.

Another important aspect that must be satisfied for the cable is a simple and fast Stripping of cable.

The cable's ability to sweep, for example, in the case of cabling in the building is widely perceived market demand, since the Stripping of the cable is an operation that engineering staff conducts manually. For this reason, it is required that the above-mentioned operation was easy and simple to conduct its operator taking also into consideration the fact that it is often carried out in narrow spaces and rather uncomfortable conditions.

Typically, the cable sheath is formed of a mixture, based with polyvinyl chloride (PVC) and also contain a plasticizer. The plasticizer tends to migrate from PVC sheath in the insulating layer, changing its composition. During the accelerated testing on aging, the applicant has observed that this effect is significant in the case newspring insulating layer. As a result, the composition has degraded electrical (insulating) properties,whereas the polar nature of the plasticizer, demonstrates weak mechanical characteristics and can cause premature aging of the cable.

Summary of invention

The applicant understood that the foamed polyolefin material could be beneficial as an insulating layer for the cable, if the polyolefin material as foamed and crosslinked. The simultaneous presence of the crosslinking and foaming allows to obtain a polyolefin material characterized by improved flexibility and easy Stripping without deterioration of the mechanical properties of the layer obtained from it.

The applicant has observed that, when trying foaming and crosslinking polyolefin degree of foaming in the General case, impossible to regulate, and it is either excessive or insufficient.

However, in the present invention the applicant has found that properly foamed and crosslinked insulating layer can be obtained by means of the stitching on a silanol-based and exothermic foaming agent. The thus obtained insulating layer is characterized by the degree of foaming is best to obtain a cable having the above characteristics.

In particular, the applicant has found that polymeric foam/stitched insulating layer improves the resistance of the cable sheath to aging.

This result, as predstavljaet is, due to the fact that such an insulating layer has a better compatibility with the materials of the shell.

Definitions

For the purposes of the present description and claims that follow, unless, stated otherwise, all numbers expressing quantities, amounts, percentages and the like, should be understood as in all cases modified by the term "approximately". In addition, all ranges include any combination of the described maximum and minimum values and include any intermediate ranges between them, which may or may not be specifically listed in this document.

In the present description, the expression "cable core" refers to a structure including at least one conductor and a corresponding electrical insulating cover placed in the external radius of the position in relation to said conductor.

For the purposes of the present description, the expression "unipolar cable" means a cable equipped with certain earlier one core, while the expression "multipolar cable" means a cable provided with at least one pair of said cores. If, more specifically, the number of cores in the multipolar cable will be equal to two, then pack the mentioned cable is technically defined as "bipolar cable, in the case of three cores mentioned cable is called "tripolar cable" and so on.

In the present description, the term "Stripping cable" is used to indicate the removal of all layers of the cable, which is placed in the position of the radial outer positions relative to the conductor, so that in the end he would have ceased to be the floor that would allow him to electrically attach to the conductor of another cable or to an electrical apparatus, for example.

In the present description, the expression "low voltage" means a voltage of less than approximately 1 kV.

In the present description and in the subsequent claims under the "conductor" refers to a conductive element of elongated shape and preferably of a metal material such as aluminum or copper.

By "insulating coating" or "insulating layer" refers to a coating or layer formed from a material characterized by constant insulation (ki), more 0,0367 Mω· km (according to the document IEC 60502).

In the present description and the claims, the term "crosslinked silane" refers to polyolefin material containing as a cross-linking element siloxane bond (-Si-O-Si-).

In the present description and the claims under the "foamed polyolefin material" means material that features resouses presence within the material of the percentage of free space, that is, the space occupied by the non-polymeric material, and a gas or air, in fact the percentage is expressed through the degree of foaming (G)defined as follows:

where d0is the density of newspring polymer, and derepresents the apparent density measured for the polymer foam.

Apparent density is measured in accordance with Italian standard regulation CEI EN 60811-1-3:2001-06.

In the present description and the claims the term "shell" involves the designation of a protective outer layer of the cable which performs the function of protecting the latter from accidental bumps or abrasions. Based on the foregoing and in accordance with the term, mentioned earlier, from the cable sheath is not required making cable special properties of electrical insulation.

In the present description and the claims under the "system stitching on a silanol-based" refers to a compound or mixture of compounds comprising at least one organic silane.

In the present description and the claims under the "system flushing" refers to a compound or mixture of compounds comprising one or more foaming agents, among which at least one is an exothermic foaming agent.

In the present description and the claims under the "endothermic foaming agent" refers to a compound or mixture of compounds which are thermally unstable and cause the absorption of heat, when a predefined temperature results in the release of gas and heat.

In the present description and the claims under the "exothermic foaming agent" refers to a compound or mixture of compounds that are thermally unstable and at a predefined temperature, decomposed with evolution of gas and heat.

In the present description and the claims under the "drawing ratio" means the ratio between the thickness of the clearance holes of the extrusion head and the final thickness of the extruded product.

In the first aspect of the present invention relates to a method of manufacturing an electric cable comprising at least one core including a conductor and an insulating coating surrounding the said conductor, while the above-mentioned method involves the following stages:

- flow polyolefin material, system of a silanol crosslinking on the basis of and system flushing, comprising at least one exothermic foaming agent in a quantity ranging from 0.1% to 0.5% (wt.) in the calculation of the cumulative mass of the polyolefin material;

- obtain a mixture of polyolefin material, system of a silanol crosslinking on the basis of and system flushing;

- extrude the Finance of the mixture on the conductor to obtain a seal.

Under "polyolefin material" refers to a polymer selected from the group including polyolefins, copolymers of different olefins, copolymers of an olefin/unsaturated esters, polyesters, and mixtures thereof. Preferably mentioned polyolefin material are: polyethylene (PE), in particular of polyethylene low density (LDPE), medium density polyethylene (PASP), high density polyethylene (HDPE) and linear low density polyethylene (LLDPE), ethylene-propylene elastomeric copolymers (EPM) or ethylene-propylene-diene terpolymer (EPDM), copolymers of ethylene/vinyl ester, such as ethylene/vinyl acetate (EVA), copolymers of ethylene/acrylate; thermoplastic copolymers of ethylene/α-olefin; and their copolymers, or of mechanical mixture.

Preferred in accordance with the invention is a polyolefin material selected from polyethylene (PE), in particular of polyethylene low density (LDPE), medium density polyethylene (PASP), high density polyethylene (HDPE) and linear low density polyethylene (LLDPE), more preferably LLDPE, optionally in a mixture with EPDM or olefin copolymer.

If the polyolefin material of the invention will be a mixture of polyethylene material and the material of the copolymer, then the last in the best case will be present in amounts in the range from 5 HR (parts per hundred parts of resin) to 30 HR.

the Preferred silanes, which can be used are (C1-C4)alkyloxyalkyl containing at least one double bond, and, in particular, vinyl - or acrylic(C1-C4)alkyloxyalkyl; compounds suitable for use in these purposes may be γ-methacryloxypropyltrimethoxysilane, VINYLTRIMETHOXYSILANE, vinyltriethoxysilane, vinylimidazole, vinyltris(2 methoxyethoxy)silane and mixtures thereof.

System of a silanol crosslinking on the basis of the method of the invention includes at least one peroxide. Preferably peroxides, which can profitably be used are di(tert-butylperoxyisopropyl-(2)-benzene, dicumylperoxide, di-tert-butylperoxide, benzoyl peroxide, tert-butylcumylperoxide, 1,1-di(tert-BUTYLPEROXY)-3,3,5-trimethylcyclohexane 2,5-bis(tert-BUTYLPEROXY)-2,5-dimethylhexane 2,5-bis(tert-BUTYLPEROXY)-2,5-dimethylhexane, tert-butyl peroxy-3,5,5-trimethylhexanoate, ethyl-3,3-di(tert-BUTYLPEROXY)butyrate, butyl-4,4-di(tert-BUTYLPEROXY)valerate and tert-butyl peroxybenzoate.

Preferably, the system stitching on a silanol-based, designed for the method of the invention includes at least one catalyst for the crosslinking, which are selected from those known at the present level of technology; and preferably it is convenient to use an organic titanate or metal to rboxylic. Particularly preferred is dilaurate dibutyrate (DLDB).

In the best case, the amount of a silanol system linkage is such that ensures the presence of a mixture from 0.003 to 0.015 mol of silane per 100 grams of polyolefin material. Preferably the amount of silane is in the range from 0,006 to 0,010 mol of silane per 100 grams of polyolefin material.

System flushing of the present method optionally includes at least one endothermic foaming agent, preferably in a quantity equal to or less 20% (wt.) when calculating the total weight of polyolefin material.

In the best case exothermic foaming agent intended for the method of the invention is an azo-compound, such as azodicarbonamide, azobisisobutyronitrile and diazoaminobenzene. Preferably exothermic foaming agent is azodicarbonamide.

Preferably exothermic foaming agent is present in an amount in the range from 0.15% to 0.24% (wt.) in the calculation of the cumulative mass of the polyolefin material.

System flushing to the polyolefin material advantageously added in the form of masterbatches containing polymeric material, preferably a homopolymer of ethylene or a copolymer, such as copolymer of ethylene/vinyl acetate (EVA), ethylene-what mobilemovie copolymer (EPR) and the copolymer of ethylene/butyl acrylate (EBA). Mentioned uterine mixture contains a foaming agent (exothermic and, in some cases endothermic) in an amount in the range from 1% (wt.) up to 80% (wt.), preferably from 5% (wt.) up to 50% (wt.), more preferably from 10% (wt.) up to 40% (wt.), in the calculation of the total mass of the polymer material.

In the best case, the system foaming additionally includes at least one activator (also called a starter). Preferred activators suitable for use in the system of foaming of the invention are compounds of transition metals.

Optional system of foaming in the method of the invention additionally contains at least one nucleating agent. Preferably the nucleating agent is active nucleating agent.

The method of the present invention is advantageously implemented in a single screw extruder.

Preferably stage extruding the mixture on the conductor in order to supply such conductor insulating layer involves the following stages:

- filing mentioned conductor extrusion machine;

- deposition of an insulating layer in the extrusion.

Stage extruding the mixture is advantageously performed using an extruding head having a reduced diameter, in accordance with the drawing ratio" (KV), less the 1, preferably lower to 0.9, more preferably less 0,8.

Optional method of manufacture corresponding to the invention, additionally includes a step for layer shell at the position of the outer peripheral radial relative position, at least one conductor having a coating in the form of the corresponding insulating layer. This stage is carried out in the extrusion.

In another aspect the present invention relates to an electrical cable comprising at least one core consisting of a conductor and an insulating coating surrounding the said guide and being in contact with him, these insulating coating consists essentially of a layer of foamed crosslinked silane polyolefin material, characterized by the degree of foaming in the range from 3% to 40%.

Preferably the electrical cable of the invention includes three previously described core.

Electric cable corresponding to the invention, preferably the cable is low voltage.

Under "polyolefin material" refers to a polymer selected from the group including polyolefins, copolymers of different olefins, copolymers of an olefin/unsaturated esters, polyesters, and mixtures thereof. Preferably, the UE is mentioned polyolefin material are: polyethylene (PE), in particular, low density polyethylene (LDPE), medium density polyethylene (PASP), high density polyethylene (HDPE) and linear low density polyethylene (LLDPE), ethylene-propylene elastomeric copolymers (EPM) or ethylene-propylene-diene terpolymer (EPDM), copolymers of ethylene/vinyl ester, such as ethylene/vinyl acetate (EVA), copolymers of ethylene/acrylate; thermoplastic copolymers of ethylene/α-olefin; and their copolymers, or of mechanical mixture.

Preferred in accordance with the invention is a polyolefin material selected from polyethylene (PE), in particular of polyethylene low density (LDPE), medium density polyethylene (PASP), high density polyethylene (HDPE) and linear low density polyethylene (LLDPE), more preferably LLDPE, optionally in a mixture with EPDM or olefin copolymer.

If the polyolefin material of the invention will be a mixture of polyethylene material and the material of the copolymer, then the last in the best case will be present in amounts in the range from 5 HR and 30 HR.

More preferably, the insulating coating of the cable of the invention is characterized by the degree of foaming in the range from 5% to 30%, even more preferably from 10% to 25%.

In the best case, the insulating coating of the cable of the invention demonstrates the foaming characterized by specific average diameter of the cells.

the particular the insulating coating of the cable of the invention in the best case is characterized by an average diameter of cells equal to or less than 300 μm, preferably equal to or less than 100 microns.

In the best case, the insulating coating of the invention is nesperennub in the peripheral portion in contact and/or adjacent to the conductor, that is, in this area, essentially no cells are not available.

Preferably the cable corresponding to the present invention, provided with a layer located at the position of the outer radial location relative to the insulating layer, preferably in contact with him.

Preferably the said layer is formed from a mixture containing polyvinyl chloride (PVC), a filler such as chalk, plasticizer, such as octyl, nonyl or decylphthalate, and additives.

In an additional aspect, the present invention relates to a method of improving the aging resistance for a cable comprising a conductor, an insulating layer and a shell where the above-mentioned insulating coating contains a crosslinked silane polyolefin material, characterized by the degree of foaming in the range from 3% to 40%.

Brief description of drawings

Additional features and advantages will become more clear in the light of the following further description of certain preferred options re the implementation of the present invention.

In the following description referring to the accompanying drawings, in which:

- figure 1 shows a transverse orthogonal cross-section for an example of the cable corresponding to the present invention;

- figure 2 is a photograph of a sample of the insulation layer from the comparative cable 17;

- figure 3 is a photograph of a sample of the insulation layer from the cable 19, corresponding to the invention;

- figure 4 is a photograph of a sample of the insulation layer from the cable 20, corresponding to the invention.

A detailed description of the preferred implementation options

Figure 1 shows the cross-section for the corresponding the invention, a cable for transmission of electrical energy at low voltage.

The cable 10 refers to a tripolar type (with three core) and includes three conductor 1, each of which Procrit foamed and cross-linked polymer insulating coating 2. Three conductor 1 together with the corresponding insulating coatings covered by the sheath 3.

Constant isolation kithe electric insulating layer 2 is such that the desired properties of electrical insulation standards-compliant (for example, IEC 60502 or other equivalent). For example, an electric insulating layer 2 is characterized by constant insulation ki, equal, and greater 3,67 Mω·km at 90°C.

The degree of foaming of the insulating layer of the cable of the invention is in the range from 3% to 40%. In particular, the applicant has found that the degree of foaming is less than 3% does not allow you to receive the cable, showing the existence of tangible benefits, expressed in flexibility and reduction of weight. On the other hand, in case of exceeding the degree of foaming 40% of the mechanical characteristics of the cable, i.e. the limit of the tensile strength deteriorated to an extent unacceptable to the requirements for the installation.

Figure 1 shows only one possible implementation of cables in which the present invention can be benefit. Therefore, in the previously mentioned implementations can be made suitable for any use, modification, such as, for example, the use of multipolar cables type or conductors sectoral cross-section.

In order to give an insulating coating suitable for use mechanical strength without compromising the flexibility of the cable, it foamed polyolefin material in accordance with the present invention is obtained from polyolefin material before foaming has a modulus of elasticity in bending in the range from 50 MPa to 1000 MPa according to the measurements carried out at room temperature in accordance with the document the m ASTM standard D790-86. Preferably, the above modulus of elasticity in bending at room temperature does not exceed 600 MPa, more preferably is made from 100 MPa to 600 MPa.

For example, the cable 1 can be produced according to the method, followed by extrusion equipment, including single-screw extruder having a diameter in the range from 60 to 175 mm and a length in the range from approximately 20 D and 30 D, and the data characteristics is chosen to match the diameter of the obtained cable and/or desired performance during development.

In the appropriate use case, the auger can be a single screw in the optional presence of a barrier round in the transition zone; together with screw no mixer device is preferably not used.

Flow in extrusion apparatus advantageously performed using multi-component dosing system gravimetric type, or preferably the volumetric type. The dosing system can feed ingredients (polyolefin material, system of a silanol crosslinking on the basis of and system flushing).

In the case of the desirability of getting colored cable (either fully painted, or with a colored surface coating) can be used uterine mixture containing pigments.

The above ingredients is ugodno serve nutritious hole of the extruder in the form of granules and to dispense with obtaining the desired percentage by system gravimetric or volumetric control. Best way to improve the dispersion of the components and the quality of the final product can pre-mixing of the ingredients out of the production line or in the bunker, located above the nutrient foramen.

System linkage, usually available in liquid form, it is not necessarily introduced into the extruder as a result of its injection into the lower part of the hopper of the extruder (the upper part of the nutrient holes) at low pressure (1 bar); the percentage of the input system of crosslinking can be controlled gravimetrically or volumetrically.

For example, the above listed ingredients are served in the nutrient foramen of the extruder, heated, melted and using auger mix along the length of the extruder, and in conclusion, metered, feeding into the guide cylinder of the extruder.

The length of the extruder chemically activated inoculation Milanovich groups to the polymer chains, and begins the process of stitching.

The foaming polyolefin material designed for insulating coatings of the invention, carried out using a special foam. Such a foaming agent is advantageously selected from the group exothermic foaming agent, in particular of azo-compounds, such as azodicarbonamide, azobisisobutyronitrile and diazoaminobenzene. Azo-compounds are prefer inim foaming agent due to their chemical inertness with respect to reagents, used when getting an insulating coating, in particular in relation to the stitching.

System flushing is mixed with other ingredients, and when a predefined temperature begins its decomposition. After completion of the reaction gas allocated to system flushing, remains dispersed within the mixture.

The mixture after passing through the filter unit serves, for example, into the guide cylinder, where it is distributed around the conductor in an orthogonal configuration with respect to the extruder. In the zone of the extrusion head conductor cover the mixture, and after the extrusion head, where the pressure release, the mixture starts foaming. After a segment of length equal to, for example, 1 m, on which the heated conductor is exposed to environmental conditions, the latter is immersed in a cooling trough, where it is subjected to cooling under the action of turbulent flow of water or other similar coolant. Cooling trough may be a type with a single pass or multiple passes.

The phase of the foaming of the extruded insulating layer terminates as soon as the melt cools, so it should be done in a short time.

At the outlet of the cooling unit insulated conductor dried, n is the sample, when using vostokstrojj system or by heating, and then is wound on the reel.

At this stage, the stitching insulating coatings of conduct is not necessary when using water and temperature; the time delay for completion of phase stitching can be reduced due to the placement of the drum with an insulated conductor inside the camera curing (sauna). In order to increase the compression of the molten mixture and to obtain a foam with improved uniformity and size of the cells, the stage of extrusion of the mixture can be accomplished by using an extruding head having a reduced diameter, in accordance with the drawing ratio" (KV).

Based on the above, in the present method, the exothermic foaming agent is present in amount ranging from 0.1% to 0.5% (wt.) in the calculation of the cumulative mass of the polyolefin material. Amounts less than 0.1% (wt.), result in a negligible degree of foaming of the polyolefin material. On the other hand, as will be demonstrated in the accompanying examples, the number, the larger of 0.5% (wt.), will lead to so large a degree of foaming, it will degrade the mechanical characteristics of products.

System foam of the invention can additionally include at least one activate is, for example, zinc compounds, cadmium or lead (oxides, salts, usually fatty acids, or other ORGANOMETALLIC compounds), amines, amides, and glycols.

The system of foaming in the method of the invention can additionally include at least one nucleating agent. The nucleating agent provides reception centers of nucleation, in which a physical foaming agent will be released from solution during expansion of the foam; center of nucleation indicates the starting point from which to begin to grow cell foam. If the nucleating agent will be able to obtain a larger number of nucleation centers, then the cells will produce more, and the average cell size will be smaller.

In the method of the invention can use two types of nucleating - active (or passive) and active nucleating. Inactive nucleating include solid materials with small particle size, such as talc, clay, diatomaceous earth, calcium carbonate, magnesium oxide and silicon dioxide. These materials serve as nucleating in the establishment in the break system, where the foaming agent is released from solution and forms a bubble. On the effectiveness of these materials is affected by the shape and size of the particles. Chemical pinoo resolutely, materials which produce gas upon decomposition, such as azodicarbonamide, also can play the role and active nucleating. The nucleation in systems of direct gassing involving chemical foaming agents are called "active nucleation". In comparison with inactive are preferred nucleating active nucleating due to the greater efficiency and the formation of smaller and more uniform cells.

The amount of a silanol system linkage is such that provides a mixture containing from 0.003 to 0.015 mol of silane per 100 grams of polyolefin material. The amount of silane, less of 0.003 mol of silane, will not provide sufficient crosslinking polyolefin material, while a number greater than 0.015 mol, in addition to its high redundancy, can lead to slippage of the screw in the extruder.

EXAMPLE 1

Low-voltage cable, as relevant, and not relevant to the present invention, produced in accordance with the cable construction shown in figure 1.

The conductor 1 was made of copper and had a cross sectional area equal to approximately 1.5 mm2.

The size of the primary EC is trader: 150/26D
The mandrel of the extrusion head:1,38 mm
The matrix of the extrusion head:2,70 mm
The dosing system masterbatches system flushing:Maguire (gravity type)

The temperature profile (°C):

Z1Z2Z3Z4Z5Z6H1H2H3H4
160180190200210220220230240240
The production line capacity:1500 m/min
Speed for the main extruder:48 rpm
Current65
Pressure380 bar
The diameter of the hot cable:2.9 mm
The diameter of the cold cable:2.9 mm

The thickness of each insulating coating was approximately 0.6 mm At the same time 0.7 mm correspond to document Italian Standard CEI-UNEL 35752 (2nd Edition - February 1990).

Each cable is subsequently cooled in water and was wound on a bobbin for storage.

In table 1 also presents the degree of foaming for each polymer mixture.

% (wt./
wt.)
Table 1
CableThe polyolefinSystem linkageSystem flushingFoaming
TypeMolTypeDensity (g/cm3)Degree (%)
1LL4004 ELSil/perox0,01--0,9260,0
2LL4004 ELSil/perox0,01Hostatron0,270,62832,2
3BPD 3220Silfin 060,006--of 0.9030,0
4BPD 3220Silfin 060,006Hostatron0,240,70022,2
5BPD 3220Silfin 060,006Hostatron0,150,860 4,4
6BPD 3220Silfin 060,008Hostatron0,150,8505,6
7BPD 3220Silfin 060,006Hostatron 50%0,150,8179,5
8BPD 3220Silfin 060,006Hostatron 50%0,180,76415,4
9BPD 3220Silfin 060,006Hostatron0,180,78712,8
10BPD 3220Sil/perox0,006Hostatron0,240,711a 21.5
11* BPD 3220Sil/perox0,12Hostatron0,090,9060,3
12BPD 3220Sil/perox0,12Hostatron0,180,8338,1
13BPD 3220Sil/perox0,12Hostatron0,240,69423,4
14 *BPD 3220Sil/perox0,006Hostatron 50%0,600,48148,0
15 *LL4004 ELSil/perox0,01Hydro-cerol0,400,61134,0
16 *BPD 3220Silfin 06 0,006Hydro-cerol0,160,8763,0
17 *BPD 3220Silfin 060,006Hydro-cerol0,450,57038,0
18BPD 3220Sil/perox0,006Hostatron 50%0,240,76415,4

Note - mol and % (wt./wt.) refer to the content of the silane or foaming agent, respectively.

Cables marked with * are comparative.

'LL 4004 EL = LLDPE, characterized by the value of MFL (the length of the yield strength of the material) 0.33 g/10 min at 190°C. under a load of 2.16 kg (ExxonMobil Chemical).

BPD 3220 = LLDPE (from BP).

Sil/perox = LUPEROX 801 (from Arkema) plus DYNASYLAN VTMO (from Degussa).

Silfin 06 = mixture of vinylsilane, the peroxide initiator and catalyst stitching (from Degussa).

Hostatron = system flushing PV22167-based foaming agent of azodicarbonamide (from the company Clariant).

Hostatron 50% = system flushing PV22167 based on what penoobrazovatel of azodicarbonamide (from the company Clariant) at levels of 50% in masterbatches EVA.

Hydrocerol = BIH 40, system flushing on the basis of a mixture of citric acid and a basic sodium carbonate as a foaming agent (from the company Clariant).

The composition of the above-mentioned mixtures shown in table 1 (in terms of mass parts per 100 mass parts of the polymer basis).

% (wt./wt.) foaming agent refers to the amount of the added foaming agent.

Cables 1 and 3 (no foaming agent is not used) is represented as reference samples to compute the degree of foaming and for conducting electrical tests cables with crosslinked and foamed insulating layer.

The cables 15*-17* isolated using polymer blends, foamed using an endothermic foaming agent (Hydrocerol).

The cables 11* 14 * isolated using polymer blends, foamed using exothermic foaming agent in a quantity beyond the preferred range. In the case of the cable 11, the degree of foaming is essentially zero, thus, in comparison with cable having newspenney insulating cover, this cable is not attached benefits, expressed in flexibility and the ability to sweep. On the other hand, the cable 14 demonstrates the presence of the insulating coating, characterized by the degree of foaming is excessive and usausa mechanical properties, as it will be demonstrated in example 3.

EXAMPLE 2

For cables from example 1 were tested to assess the degree of crosslinking of its insulating coating in accordance with Italian standard regulation CEI EN 60811-2-1:1999-05. The results are presented in table 2.

Table 2
CableFoamingthermal deformation
Density (g/cm3)Degree (%)Elongation (%)
10,9260,045
20,62832,250
3of 0.9030,090
40,70022,2110
50,8604,475
6 5,685
80,76415,4100
90,78712,890
100,711a 21.5107
120,8338,135
130,69423,445
14*0,48148,0110
15*0,61134,060
16*0,8763,0>200
17*0,76415,4destruction
180,57038,050

Ka is eaten, marked with an asterisk are comparative.

Taking into account the fact that the limit prescribed above requirement comes up to 175%, demonstrated cable 16* does not fall within the given range, that is, the polyolefin is not sufficiently made, and this has a negative impact on resistance to armodafinil. The cable 17* destroyed due to redundancy average diameter of the cells and the uneven distribution of cells in the foamed polyolefin, as illustrated in figure 2. Two cases of failure to pass tests, are given in table 2, attributed to the use of endothermic foaming agent as the sole blowing agent in the method of obtaining a crosslinked and foamed polyolefin material. An endothermic foaming agent could negatively interact with the system stitching on a silanol basis.

EXAMPLE 3

The cables, obtained in example 1 was subjected to tests to measure their mechanical properties in accordance with Italian standard regulation CEI EN 60811-1-1:2001-06, which requires ultimate tensile strength equal to at least 12,5 MPa. The results are presented in table 3.

Table 3
Cable FoamingTensile strength tensile
Density (g/cm3)Degree (%)MPa
10,9260,020,00
20,62832,212,50
3of 0.9030,020,54
40,70022,213,57
50,8604,417,37
60,8505,618,92
80,76415,416,43
90,78712,817,02
100,711a 21.518,90
120,8338,118,10
130,69423,414,10
14*0,48148,09,70
15*0,61134,09,20
180,57038,12,80

Cables marked with * are comparative.

The cable 14* isolated using polymer blends, foamed using exothermic foaming agent corresponding to the invention, but are used in quantities beyond (beyond) the limits of the selected range, and providing an insulating coating, characterized by the degree of foaming (48,0%)not relevant to the invention. This cable has demonstrated mechanical properties, suitable for use.

The cable 15* isolated using polymer blends, foamed using an endothermic foaming agent and providing an insulating covered what I characterizing the degree of foaming within the range of the invention (34,0%), however, it showed poor mechanical properties. This is due to the use of endothermic foaming agent, which makes the degree of foaming is unsatisfactory from a qualitative point of view.

EXAMPLE 4

In the following next table 4 together with the average diameter of the cells was evaluated mechanical properties and thermal deformation for the two cables that are relevant to the invention and one comparative cable.

The average diameter of the cells was evaluated as follows. Randomly chose the foamed part of the insulating coating, which is cut perpendicular to the longitudinal axis. The surface sections were examined under a microscope and pictures were received image. Measured large diameter (taking into account the fact that cells can not be perfectly round) for 50 randomly selected cells. The average for the 50 measured diameter is the average diameter of the cells.

Each cable tests were carried out for two samples. All data cables are different from the cables of the preceding examples, only the fact that the Explorer 1 had a cross sectional area equal to approximately 2.5 mm2.

Insulating coatings for cables 17* 19 EXT who was uderolal when KV = 1, and the insulating coating of the cable 20 has extrudible when KV = 0,7.

The drawing ratio was calculated as a result of comparing the cross-sectional area of the extrusion head and the cross-sectional area of the extrudate. Used the following formula:

where KV = coefficient hoods;

Dd= inner diameter of the matrix of the extrusion head;

Dm= outer diameter of the mandrel of the extrusion head;

Dt= external pipe diameter;

Db= internal pipe diameter.

Table 4
CableThe polyolefinThe foaming agentThe degree of foamingThe average diameter of cellsMechanical propertiesthermal deformation
Type% (wt./
wt.)
(%)mcmCPD (MPa)ESD (%)Elongation (%)
17 *BPD 3220 Hydrocerol0,2415,450011,03486,5Destruction for both
19BPD 3220Hostatron 50%0,181330015,61580,690; 100
20BPD 3220Hostatron 50%0,181310017,15573,380; 80
CPD = ultimate tensile strength.
ESD = elongation at break.

Cables marked with * are comparative.

The reduction in the average diameter of the cells, as was found, improves the mechanical characteristics of the insulating layer, such as thermal deformation and ultimate strength in tension.

The insulation of the cable 17* is characterized by the degree of expansion similar to that in the case of cables of the invention, but the average cell diameter of u n is e more. Large average cell diameter of the cable 17* accompanied by uneven foaming, as shown in figure 2.

The cables 19 and 20, corresponding to the invention have improved mechanical properties in comparison with the corresponding properties of the comparative cable 17*. In particular, the cable 20 is characterized by the same degree of expansion as the cable 19, but a smaller average diameter of the cells due to the lower KV during extrusion and demonstrate excellent tensile strength tensile. Mentioned cables shown in figure 3 and 4 respectively.

EXAMPLE 5

For cables of example 4 was performed tests to measure the ease of Stripping the material of the insulating coating of the conductor in comparison with nesperennub cable 3.

For each cable received six samples with a length of 120 mm, Each sample was pre-cleaned on a segment of 40 mm, so that in the test conducted in accordance with MIL-W-22759, use 80 mm sample.

The results are presented in the following table 5 further.

Table 5
CableThe degree of foaming (%)Sweep (test on obraje the spine)
Maximum load (n)Minimum load (n)The average load (n)
3-53,2723,0238,14
201316,21of 10.7313,47

The force applied to the cable stripper of the invention, less effort for the reference example in the form of a cable 3 having newpenny insulating layer. The maximum load is the force applied to trigger the sweep.

EXAMPLE 6

For the three cables, obtained in accordance with example 1 and sheathed PVC containing as plasticizer decylphthalate (shell thickness = 1,56 mm), were tested to evaluate their mechanical properties after 7 days at 100°C (aging test in accordance with EN 60811). In accordance with the requirement of the test maximum variation of ultimate tensile stress should not exceed ±25%. The results are presented in table 6.

Table 6
CableFoamingMechanical characteristics
Density (g/cm3)Degree (%)Ultimate tensile strength (MPa)Maximum variation (%)
3of 0.9030,0of 19.72±0,49-25,3±2,6
40,70022,212,25±0,63-12,2±6,4
50,8604,417,72±1,4112,4±4,9
60,8505,618,91±0,79by 12,4±5,2

Cables 4-6, corresponding to the invention, has successfully passed the test, while the cable 3 of reference example having newpenny insulating layer, not.

According to the compatibility test the presence of the foamed insulating layer improves the mechanical properties, reducing the negative consequences of migration is of plastificator, present in the cable sheath.

1. A method of manufacturing an electric cable comprising at least one core including a conductor and an insulating coating surrounding the said conductor, while the above-mentioned method involves the following stages:
supply of polyolefin material, system of a silanol crosslinking on the basis of and system flushing, comprising at least one exothermic foaming agent in an amount of from 0.1 to 0.5%, based on the total weight of polyolefin material;
obtain a mixture of polyolefin material, system of a silanol crosslinking on the basis of and system flushing;
extruding the mixture on the conductor to obtain a seal.

2. The method according to claim 1, where the polyolefin material is selected from polyolefins, copolymers of olefins, copolymers of an olefin/unsaturated esters, polyesters and mixtures thereof.

3. The method according to claim 1, where the polyolefin material is selected from low density polyethylene, medium-density polyethylene, high density polyethylene, linear low density polyethylene, ethylene-propylene elastomeric copolymers, ethylene-propylene-diene terpolymers, copolymers of ethylene/vinyl ester, copolymers, ethylene/acrylate, thermoplastic copolymers of ethylene/α-olefin and copolymers or mechanical mixture is th.

4. The method according to claim 3, where the polyolefin material is selected from low density polyethylene, medium-density polyethylene, high density polyethylene, linear low density polyethylene and mixtures thereof with ethylene-propylene-diene terpolymer or olefin copolymers.

5. The method according to claim 4, where the polyolefin material is selected from linear low density polyethylene and mixtures thereof with ethylene-propylene-diene terpolymer or olefin copolymers.

6. The method according to claim 1, where the system stitching on a silanol the base includes at least one silane selected from (C1-C4)alkyloxyalkyl containing at least one double bond.

7. The method according to claim 6, where at least one silane selected from vinyl and acrylic(C1-C4)alkyloxyalkyl.

8. The method according to claim 7, where at least one silane selected from γ-methacryloxypropyltrimethoxysilane, VINYLTRIMETHOXYSILANE, vinyltriethoxysilane, vinylimidazole, vinyltris(2 methoxyethoxy)silane and mixtures thereof.

9. The method according to claim 1, where the system stitching on a silanol the base includes at least one peroxide.

10. The method according to claim 9, where at least one peroxide selected from di(tert-butylperoxyisopropyl-(2)-benzene, dicumylperoxide, di-tert-butylperoxide, benzoyl peroxide, tert-butylcumylperoxide, 1,1-di(tert-butyl the Roxy)-3,3,5-trimethylcyclohexane, 2,5-bis(tert-BUTYLPEROXY)-2,5-dimethylhexane 2,5-bis(tert-BUTYLPEROXY)-2,5-dimethylhexane, tert-butyl peroxy-3,5,5-trimethylhexanoate, ethyl-3,3-di(tert-BUTYLPEROXY)butyrate, butyl-4,4-di(tert-BUTYLPEROXY)valerate and tert-butyl peroxybenzoate.

11. The method according to claim 1, where the system stitching on a silanol the base includes at least one catalyst for the crosslinking.

12. The method according to claim 11, where at least one catalyst for the crosslinking selected from organic titanate and metal carboxylate.

13. The method according to item 12, where at least one catalyst for the crosslinking is dilaurate dibutylamine.

14. The method according to claim 1 where the silane system stitching added in such a quantity, which ensures the presence of a mixture from 0.003 to 0.015 mol of silane per 100 g of the polyolefin material.

15. The method according to 14, where the silane system stitching added in such a quantity, which ensures the presence of a mixture from 0,006 to 0,010 mol of silane per 100 g of the polyolefin material.

16. The method according to claim 1, where the foam includes at least one endothermic foaming agent.

17. The method according to clause 16, where at least one endothermic foaming agent is present in a quantity equal to or smaller than 20%, based on the total weight of the polyolefin material.

18. The method according to claim 1, where the exothermic foaming agent t is aetsa uzasadnienie.

19. The method according to p where uzasadnienie choose from azodicarbonamide, azobisisobutyronitrile and diazoaminobenzene.

20. The method according to claim 19, where uzasadnienie is azodicarbonamide.

21. The method according to claim 1, where the exothermic foaming agent is present in an amount of from 0.1 to 0.5%, based on the total weight of the polyolefin material.

22. The method according to item 21, where the exothermic foaming agent is present in amount of from 0.15 to 0.24% (based on the total weight of the polyolefin material.

23. The method according to claim 1, where the system to foaming polyolefin material is added in the form of masterbatches containing polymeric material.

24. The method according to item 23, where the fallopian mixture containing polymeric material selected from ethylene homopolymer and ethylene copolymer.

25. The method according to paragraph 24, where the fallopian mixture containing polymeric material selected from a copolymer of ethylene/vinyl acetate, ethylene-propylene copolymer and copolymer ethylene/butyl acrylate.

26. The method according to item 23, where the fallopian mixture contains a blowing agent in an amount of from 1 to 80%, based on total weight of polymeric material.

27. The method according to p, where the amount of the foaming agent is from 5 to 50%, based on total weight of polymeric material.

28. The method according to item 27, where the amount of the foaming agent is from 10 to 40%, based on the total weight of polymeric material.

29. The method according to claim 1, where the foam includes at least one activator.

30. The method according to clause 29, where at least one activator selected from compounds of transition metals.

31. The method according to claim 1, where the foam includes at least one nucleating agent.

32. The method according to p, where at least one nucleating agent is active nucleating agent.

33. The method according to claim 1, where the stage of obtaining a mixture of polyolefin material, system of a silanol crosslinking on the basis of and system flushing carried out in a single screw extruder.

34. The method according to p, where the flow in the extruder is carried out using multi-component dosing system volumetric type.

35. The method according to claim 1, where the stage of obtaining a mixture of polyolefin material, system of a silanol crosslinking on the basis of and system flushing is preceded by a stage of mixing the polyolefin material, system of a silanol crosslinking on the basis of the system and flushing out of the production line.

36. The method according to claim 1, where the stage of extrusion of the mixture on the conductor in order to provide such a conductor with an insulating coating involves the following stages:
submission-mentioned conductor extrusion machine;
the deposition of the insulating layer in the extrusion.

37. The method according to claim 1, where the extra stage is investing mixture is conducted by means of the extrusion head with the drawing ratio, less 1.

38. The method according to clause 37, where the drawing ratio is less than 0.9.

39. The method according to § 38, where the drawing ratio is less than 0.8.

40. The method according to claim 1, comprising a stage of extrusion layer shell in the outer radius of the peripheral position in relation, at least one conductor having a coating in the form of an appropriate insulating coating.

41. Electric cable comprising at least one core consisting of a conductor and an insulating coating surrounding the said guide and being in contact with him, these insulating coating consists essentially of a layer of foamed crosslinked silane polyolefin material, characterized by the degree of expansion from 3 to 40%.

42. Electric cable according to paragraph 41, which is cable low voltage.

43. Electric cable according to paragraph 41, containing three of the core.

44. Electric cable according to paragraph 41, where the polyolefin material is selected from polyolefins, copolymers of olefins, copolymers of an olefin/unsaturated esters, polyesters and mixtures thereof.

45. Electric cable according to item 44, where the polyolefin material is selected from low density polyethylene, medium-density polyethylene, high density polyethylene, linear low density polyethylene, ethylene-ol is bilinovich elastomeric copolymers, ethylene-propylene-diene terpolymers, copolymers of ethylene/vinyl ester, copolymers, ethylene/acrylate, thermoplastic copolymers of ethylene/α-olefin and copolymers or mechanical mixtures.

46. Electric cable according to item 45, where the polyolefin material is selected from low density polyethylene, medium-density polyethylene, high density polyethylene, linear low density polyethylene and mixtures thereof with ethylene-propylene-diene terpolymer or olefin copolymers.

47. Electric cable according to item 46, where the polyolefin material is selected from linear low density polyethylene and mixtures thereof with ethylene-propylene-diene terpolymer or olefin copolymers.

48. Electric cable according to item 46, where the polyolefin material of the invention is a mixture of polyethylene material and the material of the copolymer, while the latter is present in an amount of 5 to 30 HR.

49. Electric cable according to paragraph 41, where the insulating coating is characterized by a degree of foaming of from 5 to 30%.

50. Electric cable according to § 49, where the insulating coating is characterized by a degree of foaming of from 10 to 25%.

51. Electric cable according to paragraph 41, where the insulation is characterized by an average diameter of cells equal to or less than 300 microns.

52. Electric cable according to § 51, where the insulation is characterized by a mean diameter of I the EEK, equal to or less than 100 microns.

53. Electric cable according to paragraph 41, where the peripheral (environment) part of the foamed insulating coating in contact with the conductor, is newspronet.

54. Electric cable according to paragraph 41, which is provided with a layer outside of the radial direction position relative to the insulating layer.

55. Method for improving the aging resistance for a cable comprising a conductor, an insulating layer and a shell where the above-mentioned insulating coating contains a crosslinked silane polyolefin material, characterized by the degree of expansion from 3 to 40%.



 

Same patents:

FIELD: electrical engineering including cable engineering; midget control cables for wire communication lines of small-size missiles and their manufacturing process.

SUBSTANCE: proposed midget control cable has two electrically insulated enameled copper conductors (current-carrying conductors), one strengthening complex thread of cross securing lea winding of three polyamide threads forming thread assembly, as well as seven strengthening complex threads placed on top of cross securing winding in parallel with copper conductors, and secondary securing winding of one complex strengthening thread; thread assembly is impregnated with water-repelling liquid. Proposed method for manufacturing midget control cable includes manufacture of thread assembly followed by finishing midget control cable for which purpose seven strengthening complex threads are arranged in parallel with thread assembly whereupon finished midget control wire is wound on take-in reel.

EFFECT: improved electrical and mechanical characteristics, ability of using cable immersed in water including sea water.

2 cl, 2 dwg

FIELD: electrical engineering including cable engineering; midget control cables for wire communication lines of small-size missiles and their manufacturing process.

SUBSTANCE: proposed midget control cable has two electrically insulated enameled copper conductors (current-carrying conductors), one strengthening complex thread of cross lea securing winding of three polyamide threads forming thread assembly, as well as four strengthening complex threads placed on top of cross securing winding in parallel with copper conductors, two-layer lea winding of two polyamide threads wound in opposite directions, and one complex thread. Proposed method for manufacturing midget control cable includes manufacture of thread assembly followed by finishing midget control cable for which purpose four strengthening complex threads are arranged in parallel with thread assembly and two-layer winding is placed overall.

EFFECT: improved electrical and mechanical characteristics, ability of using cable immersed in water including sea water.

2 cl, 3 dwg

Electric cable // 2309474

FIELD: cable engineering; feeding submersible power systems, primarily electric motors of submersible oil pumps.

SUBSTANCE: proposed oil-pump motor feeding cable designed for long-time service in boreholes at depths up to 3 000 m and stratal liquid temperatures of 80 to 210 °C has insulated current-carrying conductors and thermoelastolayer sheath disposed on each conductor and/or on all conductors; conductor insulation is made of acid-free radiation-modified high-density polyethylene and sheath, of thermoelastolayer. Such mechanical design of cable whose conductors are covered with air-tight insulation provides for radiation modification of high-density polyethylene dispensing with specific mechanical devices and attachments.

EFFECT: improved electrophysical and mechanical characteristics of insulation maintained even at high-speed cable lifting upon long-time service in boreholes; extended cable service life.

1 cl, 2 dwg, 1 tbl

Electric cable // 2303307

FIELD: cable engineering; feeding submersible power systems of oil-extracting pump motors.

SUBSTANCE: proposed cable designed for use at depth of up to 3000 m, stratal liquid temperature of 140 to 210 °C, gas factor over 300 m3/t, and pressure of up to 30 MPahas current-carrying conductors insulated by radiation-modified polyethylene, sheath, pad, and armor, as well as additional sheath made of thermoelastic plastic layer, 0.2 to 0.7 mm thick, that covers insulation of each current-carrying conductor, surface layer of double-layer insulation being plasma pre-treated.

EFFECT: enhanced service life of cable.

1 cl, 1 dwg

Electric cable // 2302678

FIELD: cable engineering; feeding submersible power systems, mainly submersible oil-extraction pump motors.

SUBSTANCE: proposed cable designed for trouble-free operation in depths of up to 3000 m at stratal liquid temperature of 140 to 160 °C and gas factor over 300 m3/t has current-carrying conductors covered with adhesive radiation-modified polyethylene layers, sheath, pad, and armor; common additional sheath is made of thermoplastic material, 0.1 - 1.0 mm thick on flat side and 1.0 - 1.5 mm, on lateral sides; it is disposed over three insulated conductors longitudinally placed in common plane and tightly fitted to one another through their plasma pre-treated insulation.

EFFECT: extended service life of cable.

1 cl, 1 dwg

Insulating sheath // 2270489

FIELD: electric insulation engineering; insulating sheaths possessing fire and heat resistance and screening effect.

SUBSTANCE: proposed insulating sheath characterized in high resistance to open flame, high temperatures up to 600 °C, acids, oil products, organic solvents, and microbiological impacts is made of threads having different composition and twisted together; one of threads is made of arimide fiber and functions as reinforcing warp, and other one is made in the form of metal thread, more than 0.018 and less than 0.020 mm thick, that functions as shielding component. Coated or non-coated metal wire is used as shielding component. Reinforcing warp can be made in the form of harness of at least two arimide threads twisted together or it may have a few pairs of arimide fiber threads and metal thread twisted together; these pairs are interwoven to form ribbon or cloth.

EFFECT: enhanced fire resistance and flexibility, reduced weight of insulating sheath.

5 cl, 1 tbl

FIELD: electrical and radio engineering.

SUBSTANCE: proposed high-voltage conductor designed for erecting dc and ac power transmission lines and also for use as conductor of heavy-power low-frequency radio transmitting antennas has concentrically disposed weight carrying member, radius R1 conductor, internal semiconductor insulating layer, external semiconductor insulating layer, and radius Re main insulating layer. Internal semiconductor insulating layer is required for fashioning current-carrying conductor in the form of round cylinder and for smoothing down irregularities capable of enhancing electric field strength and liable to cause partial discharges. External semiconductor insulating layer is used for fast equalization of potential throughout entire external surface of conductor. Operating voltage across conductor may exceed corona firing potential Vc in vicinity of insulator-air boundary by 1.4 to 3 times at specified corona power loss. Novelty is that relative radius x = Re/R1 and volume resistivity ρ of main insulating layer in high-voltage conductor with known corona-discharge current-voltage characteristic I(V1) and at specified corona power loss are interrelated by definite equations for frequencies f > fb and f < fb, where fb is value reverse to charge time constant of circuit set up of corona discharge resistance and total capacitance of system.

EFFECT: ability of conductor operation at voltage exceeding corona firing voltage near certain boundary.

2 cl, 6 dwg

Electric cable // 2256969

FIELD: electrical engineering; electric cables for signaling, control, and data transfer and processing systems.

SUBSTANCE: cable has at least one pair of insulated and stranded current-carrying conductors and cable sheath. Insulating material is either halogen-containing polymer (polyvinyl chloride), or halogen-free polyolefin base material (polyethylene), or its copolymer. Insulation thickness is chosen from equation strand pitch is found from equation h = 25(2Δ + d), where d is conductor diameter; εr is relative dielectric constant of insulating material. With diameter of cable current-carrying conductors being enlarged, capacitance of cable pair was reduced (other characteristics being retained at desired level.

EFFECT: enhanced capacitance of working load on cable pair.

1 cl, 4 dwg, 1 tbl

The invention relates to insulation for electric wires or cables

Electric wire // 2154867
The invention relates to a cable technique, namely, to designs wires

Electric cable // 2256969

FIELD: electrical engineering; electric cables for signaling, control, and data transfer and processing systems.

SUBSTANCE: cable has at least one pair of insulated and stranded current-carrying conductors and cable sheath. Insulating material is either halogen-containing polymer (polyvinyl chloride), or halogen-free polyolefin base material (polyethylene), or its copolymer. Insulation thickness is chosen from equation strand pitch is found from equation h = 25(2Δ + d), where d is conductor diameter; εr is relative dielectric constant of insulating material. With diameter of cable current-carrying conductors being enlarged, capacitance of cable pair was reduced (other characteristics being retained at desired level.

EFFECT: enhanced capacitance of working load on cable pair.

1 cl, 4 dwg, 1 tbl

FIELD: electrical and radio engineering.

SUBSTANCE: proposed high-voltage conductor designed for erecting dc and ac power transmission lines and also for use as conductor of heavy-power low-frequency radio transmitting antennas has concentrically disposed weight carrying member, radius R1 conductor, internal semiconductor insulating layer, external semiconductor insulating layer, and radius Re main insulating layer. Internal semiconductor insulating layer is required for fashioning current-carrying conductor in the form of round cylinder and for smoothing down irregularities capable of enhancing electric field strength and liable to cause partial discharges. External semiconductor insulating layer is used for fast equalization of potential throughout entire external surface of conductor. Operating voltage across conductor may exceed corona firing potential Vc in vicinity of insulator-air boundary by 1.4 to 3 times at specified corona power loss. Novelty is that relative radius x = Re/R1 and volume resistivity ρ of main insulating layer in high-voltage conductor with known corona-discharge current-voltage characteristic I(V1) and at specified corona power loss are interrelated by definite equations for frequencies f > fb and f < fb, where fb is value reverse to charge time constant of circuit set up of corona discharge resistance and total capacitance of system.

EFFECT: ability of conductor operation at voltage exceeding corona firing voltage near certain boundary.

2 cl, 6 dwg

Insulating sheath // 2270489

FIELD: electric insulation engineering; insulating sheaths possessing fire and heat resistance and screening effect.

SUBSTANCE: proposed insulating sheath characterized in high resistance to open flame, high temperatures up to 600 °C, acids, oil products, organic solvents, and microbiological impacts is made of threads having different composition and twisted together; one of threads is made of arimide fiber and functions as reinforcing warp, and other one is made in the form of metal thread, more than 0.018 and less than 0.020 mm thick, that functions as shielding component. Coated or non-coated metal wire is used as shielding component. Reinforcing warp can be made in the form of harness of at least two arimide threads twisted together or it may have a few pairs of arimide fiber threads and metal thread twisted together; these pairs are interwoven to form ribbon or cloth.

EFFECT: enhanced fire resistance and flexibility, reduced weight of insulating sheath.

5 cl, 1 tbl

Electric cable // 2302678

FIELD: cable engineering; feeding submersible power systems, mainly submersible oil-extraction pump motors.

SUBSTANCE: proposed cable designed for trouble-free operation in depths of up to 3000 m at stratal liquid temperature of 140 to 160 °C and gas factor over 300 m3/t has current-carrying conductors covered with adhesive radiation-modified polyethylene layers, sheath, pad, and armor; common additional sheath is made of thermoplastic material, 0.1 - 1.0 mm thick on flat side and 1.0 - 1.5 mm, on lateral sides; it is disposed over three insulated conductors longitudinally placed in common plane and tightly fitted to one another through their plasma pre-treated insulation.

EFFECT: extended service life of cable.

1 cl, 1 dwg

Electric cable // 2303307

FIELD: cable engineering; feeding submersible power systems of oil-extracting pump motors.

SUBSTANCE: proposed cable designed for use at depth of up to 3000 m, stratal liquid temperature of 140 to 210 °C, gas factor over 300 m3/t, and pressure of up to 30 MPahas current-carrying conductors insulated by radiation-modified polyethylene, sheath, pad, and armor, as well as additional sheath made of thermoelastic plastic layer, 0.2 to 0.7 mm thick, that covers insulation of each current-carrying conductor, surface layer of double-layer insulation being plasma pre-treated.

EFFECT: enhanced service life of cable.

1 cl, 1 dwg

Electric cable // 2309474

FIELD: cable engineering; feeding submersible power systems, primarily electric motors of submersible oil pumps.

SUBSTANCE: proposed oil-pump motor feeding cable designed for long-time service in boreholes at depths up to 3 000 m and stratal liquid temperatures of 80 to 210 °C has insulated current-carrying conductors and thermoelastolayer sheath disposed on each conductor and/or on all conductors; conductor insulation is made of acid-free radiation-modified high-density polyethylene and sheath, of thermoelastolayer. Such mechanical design of cable whose conductors are covered with air-tight insulation provides for radiation modification of high-density polyethylene dispensing with specific mechanical devices and attachments.

EFFECT: improved electrophysical and mechanical characteristics of insulation maintained even at high-speed cable lifting upon long-time service in boreholes; extended cable service life.

1 cl, 2 dwg, 1 tbl

FIELD: electrical engineering including cable engineering; midget control cables for wire communication lines of small-size missiles and their manufacturing process.

SUBSTANCE: proposed midget control cable has two electrically insulated enameled copper conductors (current-carrying conductors), one strengthening complex thread of cross lea securing winding of three polyamide threads forming thread assembly, as well as four strengthening complex threads placed on top of cross securing winding in parallel with copper conductors, two-layer lea winding of two polyamide threads wound in opposite directions, and one complex thread. Proposed method for manufacturing midget control cable includes manufacture of thread assembly followed by finishing midget control cable for which purpose four strengthening complex threads are arranged in parallel with thread assembly and two-layer winding is placed overall.

EFFECT: improved electrical and mechanical characteristics, ability of using cable immersed in water including sea water.

2 cl, 3 dwg

FIELD: electrical engineering including cable engineering; midget control cables for wire communication lines of small-size missiles and their manufacturing process.

SUBSTANCE: proposed midget control cable has two electrically insulated enameled copper conductors (current-carrying conductors), one strengthening complex thread of cross securing lea winding of three polyamide threads forming thread assembly, as well as seven strengthening complex threads placed on top of cross securing winding in parallel with copper conductors, and secondary securing winding of one complex strengthening thread; thread assembly is impregnated with water-repelling liquid. Proposed method for manufacturing midget control cable includes manufacture of thread assembly followed by finishing midget control cable for which purpose seven strengthening complex threads are arranged in parallel with thread assembly whereupon finished midget control wire is wound on take-in reel.

EFFECT: improved electrical and mechanical characteristics, ability of using cable immersed in water including sea water.

2 cl, 2 dwg

FIELD: power engineering.

SUBSTANCE: method is described for manufacturing of electric cable (10), comprising at least one core, which includes conductor (1) and insulating coating (2), which surrounds conductor, at the same time method includes the following stages: supply of polyolefine material, cross-linking system on silane basis and foam generation system, comprising at least one exothermic foaming agent in amount of at least 0.1% - 0.5% (wt) per total mass of polyolefine material; production of polyolefine material mixture, cross-linking system on silane basis and foam generation system; and extrusion of mixture to conductor (1) to make insulating coating (2). Also electric (10) is described, which comprises at least one core, which consists of conductor (1) and insulating coating (2), which surrounds mentioned conductor (1) and is in contact with it, at the same time insulating coat (2) mainly consists of a layer of foamed silane-linked polyolefine material, characterised with extent of foaming in the range from 3% to 40%.

EFFECT: increased flexibility of cable, improved mechanical characteristics and electric properties.

55 cl, 6 tbl, 6 ex

Electric cable // 2424592

FIELD: electricity.

SUBSTANCE: electric cable includes current-conducting cords insulated with thermoplastics and sheath from thermoplastic elastomer, which is located on each cord and/or on all together; at that, cord insulation is made from oxygen-free-radiation-modified thermoplastic material through sheath, and sheath is made from thermoplastic elastomer soaked with non-saturated hydrocarbons. Saturation of insulation from thermoplastic material with non-saturated hydrocarbons also improves cable characteristics. Gap made between insulated cords in cable with common sheath increases its operating life.

EFFECT: longer operating life of cable at operation in contact with corrosive medium.

7 cl, 2 dwg

Up!