Corrosion-resistant polypropylene insulated cable and preparation process thereof

Abstract

The application discloses a kind of corrosion-resistant polypropylene insulated cables and preparation process thereof, belong to cable technical field;The corrosion-resistant polypropylene insulated cable of the application includes cable core, wrapping layer, inner sheath layer, armored layer, outer sheath layer in turn from inside to outside;Inner sheath layer and outer sheath layer are made of corrosion-resistant polypropylene cable material;Corrosion-resistant polypropylene cable material raw material component includes polypropylene, POE, plasticizer, composite flame retardant, heat-conducting filler, lubricant, ultraviolet absorber, nucleating agent;Composite flame retardant is made of cyanuric chloride, 4-hydroxymethyl-1-oxo-1-phosphorus-2,6,7-trioxa-bicyclo [2.2.2] octane, hydroxyl N-alkoxy hindered amine and ethylenediamine, N-(2-aminoethyl) maleimide as raw material;Heat-conducting filler is made of graphene oxide, silane coupling agent, boron nitride, 3,5-di-tert-butyl-4-hydroxycinnamic acid as raw material;The corrosion-resistant polypropylene insulated cable prepared by the application has good corrosion resistance, heat dissipation, flame retardance, heat-oxidative aging resistance and mechanical properties.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cables, in particular to a corrosion-resistant polypropylene insulated cable and a preparation process thereof. BACKGROUND

[0002] With the rapid development of modern industry, energy, transportation and construction fields, the performance requirements of power transmission systems for cables are increasingly stringent. As a thermoplastic polymer, polypropylene has gradually become a research hotspot for power cable insulation materials in recent years due to its excellent electrical insulation performance, low dielectric constant, good processing performance, environmental protection and recyclability, and is considered as a potential substitute for traditional cross-linked polyethylene. However, polypropylene material itself has defects such as poor heat resistance, easy aging, and weak resistance to environmental stress cracking, especially in complex and harsh application environments such as chemical plant areas, coastal areas, underground pipe networks or high temperature and high humidity places. The cable sheath layer is easily eroded by corrosive media such as acid, alkali and salt mist, leading to material performance degradation and insulation failure, which seriously threatens the safe and stable operation of the power system.

[0003] In addition, during the operation of the cable, heat is generated due to the resistance of the conductor. If the cable has poor heat dissipation performance, the accumulation of heat will accelerate the aging of the material, reduce the cable carrying capacity, and affect its service life. At the same time, the traditional polypropylene material has poor flame retardant performance and belongs to flammable materials, which may spread the fire in extreme cases such as fire, and there is a great safety hazard.

[0004] Therefore, it has become a technical problem to be solved in the field of cable materials to develop a polypropylene insulated cable with excellent corrosion resistance, high heat dissipation and good flame retardance. SUMMARY

[0005] The purpose of the present application is to provide a corrosion-resistant polypropylene insulated cable and a preparation process thereof to solve the technical problems mentioned in the background.

[0006] The technical solution to achieve the purpose of the present application is:

[0007] In a first aspect, the present application provides a corrosion-resistant polypropylene insulated cable, which comprises, from inside to outside, a cable core, a wrapping layer, an inner sheath layer, an armor layer and an outer sheath layer. The cable core comprises a reinforcing core and at least two electrical units symmetrically arranged around the reinforcing core. The electrical unit comprises, from inside to outside, a conductor, a conductor shield layer, an insulation layer and a metal shield layer. The inner sheath layer and the outer sheath layer are both made of corrosion-resistant polypropylene cable material.

[0008] Further, the raw material components of the corrosion-resistant polypropylene cable material mainly include 70-90 parts by mass of polypropylene, 10-30 parts by mass of POE, 10-15 parts by mass of plasticizer, 18-20 parts by mass of composite flame retardant, 4-5 parts by mass of thermal conductive filler, 1-1.5 parts by mass of lubricant, 0.2-0.7 parts by mass of ultraviolet absorber, and 0.1-0.6 parts by mass of nucleating agent.

[0009] Further, the composite flame retardant is prepared from tricyanochloride, 1-oxo-4-hydroxymethyl-1-phosphorus-2, 6, 7-trioxa-bicyclo[2.2.2]octane, hydroxyl N-alkoxy hindered amine, and ethylenediamine, N-(2-aminoethyl) maleimide.

[0010] Further, the thermal conductive filler is prepared from graphene oxide, silane coupling agent, boron nitride, and 3, 5-di-tert-butyl-4-hydroxycinnamic acid.

[0011] Further, the silane coupling agent includes amino silane coupling agent and mercapto silane coupling agent.

[0012] In a second aspect, a preparation process of the corrosion-resistant polypropylene insulated cable according to the first aspect includes the following preparation steps:

[0013] A1. Preparation of an electric unit;

[0014] A2. Arranging and disposing at least two electric units around a reinforcing core to obtain a cable core;

[0015] A3. Wrapping a wrapping layer outside the cable core;

[0016] A4. Extruding the corrosion-resistant polypropylene cable material outside the wrapping layer to obtain an inner sheath layer;

[0017] A5. Coating a sheath layer outside the inner sheath layer;

[0018] A6. Extruding the corrosion-resistant polypropylene cable material outside the sheath layer to obtain an outer sheath layer.

[0019] Further, the preparation steps of the corrosion-resistant polypropylene cable material are as follows:

[0020] B1. Weighing and batching each raw material component according to the corresponding mass fraction;

[0021] B2. The weighed polypropylene, composite flame retardant, and thermal conductive filler are mixed and placed in a banbury mixer at 175-185℃ for 15-25 minutes, then 0.17-0.23 parts by mass of dicumyl peroxide is added and the mixing is continued for 15-25 minutes, then POE and maleic anhydride grafted polypropylene are added and melt blended for 10-20 minutes, then plasticizer, lubricant, ultraviolet absorber, and nucleating agent are added and melt blended for 10-20 minutes, and then the mixture is extruded and pelletized in a twin-screw extruder to obtain the corrosion-resistant polypropylene cable material.

[0022] Further, the reinforcing core is aramid fiber; the insulating layer is high-temperature-resistant 150℃ radiation crosslinking flame-retardant polyolefin insulating material; the wrapping layer is a halogen-free low-smoke high-flame-retardant tape made of non-woven fabric or glass fiber fabric material, wrapped around the cable core to obtain a cover rate of 15-20%; the conductor shielding layer is an aluminum-plastic composite tape; and the metal shielding layer is an aluminum foil Mylar tape.

[0023] Further, the composite flame retardant is prepared by the following method: hydroxyl N-alkoxy hindered amine, cyanuric chloride, and acetonitrile are mixed, the mass-volume ratio of hydroxyl N-alkoxy hindered amine to acetonitrile is 1g:90-100mL, and stirring is performed at 0-5℃ until dissolution, then acetonitrile solution of triethylamine with a mass-volume ratio of 1g:100-600mL is added dropwise, and the reaction is continued for 3-5h to obtain a mixed solution A, wherein the molar ratio of hydroxyl N-alkoxy hindered amine, cyanuric chloride, and triethylamine is 1:1:1; cyanuric chloride, 4-hydroxymethyl-1-oxo-1-phospha-2,6,7-trioxa- bicyclo[2.2.2]octane, and acetonitrile are mixed, stirring is performed at 0-5℃ until dissolution, then triethylamine is added dropwise, and the reaction is continued for 3-5h to obtain a mixed solution B, wherein the molar ratio of cyanuric chloride, 4-hydroxymethyl-1-oxo-1-phospha-2,6,7-trioxa-bicyclo[2.2.2]octane, and triethylamine is 1:1:1; the mass-volume ratio of cyanuric chloride to acetonitrile is 1g:15-20mL; the mixed solution A and the mixed solution B are mixed uniformly, then ethylenediamine and 1 / 2 triethylamine are added dropwise after heating to 55℃, and N-(2-aminoethyl) maleimide is added and the reaction is continued for 3-5h, then the temperature is increased to reflux temperature, the remaining triethylamine is added dropwise and the reaction is continued for 3-5h, after the reaction is completed, the solvent is removed by suction filtration, the product is washed with deionized water for three times and dried to obtain the composite flame retardant, wherein the molar ratio of ethylenediamine, N-(2-aminoethyl) maleimide, and triethylamine is (0.7-0.8):(0.2-0.3):2; and the molar ratio of hydroxyl N-alkoxy hindered amine, 4-hydroxymethyl-1-oxo-1-phospha-2,6,7-trioxa-bicyclo[2.2.2]octane, and ethylenediamine is (0.003-0.007):1:(1-1.01).

[0024] Further, the preparation method of the heat-conducting filler is as follows: 0.5 parts by mass of graphene oxide is added into N,N-dimethylformamide in a mass-volume ratio of 1 g: 300-500 mL for ultrasonic dispersion for 4-6 h, then 18-20 parts by mass of amino silane coupling agent and 0.8-1.2 parts by mass of dicyclohexyl carbodiimide are added, and the reaction is carried out at 68-72 DEG C for 11-13 h under stirring, after which the obtained reaction solution is subjected to vacuum filtration treatment through a PVDF filter membrane, and the solid is collected, then the obtained solid is washed with tetrahydrofuran and anhydrous ethanol for multiple times, after washing, the solid and 18-20 parts by mass of mercapto silane coupling agent are dispersed in 250-350 parts by mass of ethanol again, then 25-35 parts by mass of deionized water and 4-6 parts by mass of acetic acid are added, and after stirring at room temperature for 50-70 min, 0.2-0.3 parts by mass of hydroxylated boron nitride is added, and then the reaction is carried out at 75-80 DEG C for 5-7 h, then the solid is collected by filtration and washing with ethanol and deionized water for multiple times and dried, then the dried solid is dispersed in 150-250 parts by mass of cyclohexane, then 20-30 parts by mass of 3,5-di-tert-butyl-4-hydroxycinnamic acid and 0.4-0.8 parts by mass of p-toluene sulfonic acid are added, then the reaction is carried out at 78-82 DEG C for 9-11 h under stirring, and then the cyclohexane is recovered by distillation under reduced pressure, and the obtained solid is washed with saturated sodium bicarbonate solution, then washed with water until neutral, and dried to obtain the heat-conducting filler.

[0025] Further, the armored layer is woven by galvanized steel wires.

[0026] By adopting the technical scheme, the present application has the following beneficial effects:

[0027] (1) The corrosion-resistant polypropylene insulated cable comprises a cable core, a wrapping layer, an inner sheath layer, an armored layer and an outer sheath layer from inside to outside; the cable core comprises a reinforcing core arranged at the center and at least two electrical units symmetrically arranged around the reinforcing core; the structure design not only improves the overall mechanical strength of the cable, but also realizes the symmetry and stability of current transmission; each electrical unit comprises a conductor, a conductor shielding layer, an insulation layer and a metal shielding layer from inside to outside; the conductor shielding layer and the insulation layer cooperate to effectively and uniformly distribute the electric field and suppress partial discharge; the metal shielding layer has good grounding performance and short-circuit current carrying capacity, thereby ensuring the safe operation of the cable; the inner sheath layer and the outer sheath layer are made of corrosion-resistant polypropylene cable material, and the prepared polypropylene insulated cable has excellent corrosion resistance, good heat dissipation and reliable flame retardance.

[0028] (2) The corrosion-resistant polypropylene cable material raw material components used by the inner sheath layer and the outer sheath layer of the application include polypropylene, POE, plasticizer, composite flame retardant, heat-conducting filler, lubricant, ultraviolet absorber, nucleating agent; by adding the composite flame retardant and the heat-conducting filler, the corrosion resistance, the heat conductivity and the flame retardance of the corrosion-resistant polypropylene cable material can be effectively improved.

[0029] (3) The composite flame retardant of the application is prepared from tricyanuric chloride, 4-hydroxymethyl-1-oxo-1-phospha-2,6,7-trioxa-bicyclo[2.2.2]octane, hydroxyl N-alkoxy hindered amine and ethylenediamine, and N-(2-aminoethyl) maleimide; the synthesis process is as follows: first, under low temperature conditions, equimolar tricyanuric chloride and hydroxyl N-alkoxy hindered amine undergo nucleophilic substitution reaction, in which one chlorine atom is replaced by the hydroxyl hindered amine to generate intermediate 1; subsequently, equimolar tricyanuric chloride and 1-oxo-4-hydroxymethyl-1-phospha-2,6,7-trioxa-bicyclo[2.2.2]octane react to generate phosphorus-containing intermediate 2 through condensation of the hydroxyl group and the active chlorine atom of tricyanuric chloride; finally, intermediate 1 and intermediate 2 are mixed, and the remaining active chlorine atoms in the molecules thereof further undergo nucleophilic substitution reaction with the primary amino groups in ethylenediamine and N-(2-aminoethyl) maleimide to form the composite flame retardant; the composite flame retardant integrates the phosphorus-nitrogen-hindered amine synergistic flame-retardant system, and has dual flame-retardant mechanisms of gas phase and condensed phase; among them, the hydroxyl N-alkoxy hindered amine is not only a high-efficiency radical capture type light stabilizer, but also can generate stable nitroxyl radicals under the action of light or heat, effectively quenching the alkyl radicals and peroxide radicals generated in the thermal oxidation process of polypropylene, delaying material aging, and at the same time, still releasing nitroxyl radicals under high-temperature combustion conditions, efficiently capturing active radicals generated by polypropylene cracking in the gas phase, interrupting the radical chain reaction, and significantly inhibiting flame propagation. In addition, the hindered amine structure in the condensed phase can promote macromolecular radicals to crosslink into carbon, and cooperates with the phosphorus-containing component to form a carbon layer on the material surface, which is dense, continuous and rich in P-O-C and P-N structures, has good thermal stability and heat and oxygen insulation properties, effectively blocks the internal heat transfer and the combustible cracking products from diffusing outward, thereby inhibiting the further pyrolysis and combustion of polypropylene, significantly improving the flame retardance of the polypropylene cable material, and at the same time, the stable hindered amine unit in the structure also endows the material with excellent anti-aging ability, realizing synchronous improvement of the flame retardance and weather resistance.

[0030] (4) The heat-conducting filler of the present application is prepared from graphene oxide, silane coupling agent, boron nitride and 3,5-di-tert-butyl-4-hydroxycinnamic acid as raw materials, and the silane coupling agent includes amino silane coupling agent and mercapto silane coupling agent; firstly, the amino group on the amino silane coupling agent reacts with the carboxyl group on the surface of graphene oxide to form a stable bond through amidation; then, the siloxyl group in the unreacted amino silane coupling agent and the siloxyl group in the mercapto silane coupling agent condense with the hydroxyl group on the surface of the hydroxylated boron nitride to realize the effective connection of graphene oxide and boron nitride; finally, the mercapto group reacts with the carboxyl group on the 3,5-di-tert-butyl-4-hydroxycinnamic acid through esterification to graft 3,5-di-tert-butyl-4-hydroxycinnamic acid thioester; the hindered phenol part in this structure captures free radicals through the hydrogen transfer mechanism during the polymer stabilization process, prevents the oxidation chain from growing, and leads to the generation of polymer hydroperoxide; however, the polymer hydroperoxide is easily decomposed under the action of light, heat and the like to generate new free radicals to continue to initiate the oxidation process; the thioester part can effectively decompose these hydroperoxides to convert them into stable alcohol products, thereby exhibiting a self-synergistic stabilization effect and further improving the thermal oxidative aging resistance of the polypropylene cable material.

[0031] Furthermore, the introduction of boron nitride increases the interlayer spacing of graphene oxide, reduces the agglomeration tendency of graphene oxide, increases the dispersibility of graphene oxide, and also enables the heat-conducting filler to occupy more space in the material; the combination of boron nitride and graphene oxide utilizes the shielding effect of both, effectively prolonging the diffusion path of corrosive ions in the material and enhancing the corrosion resistance of the cable material; since both boron nitride and graphene oxide are insulating two-dimensional materials, their combined action can significantly improve the charge transfer resistance and hinder the conduction of electrons at the corrosion interface, thereby further improving the corrosion resistance of the cable material.

[0032] In summary, the prepared corrosion-resistant polypropylene cable material has good thermal conductivity, corrosion resistance and thermal oxidative aging resistance.

[0033] (5) In the preparation of the corrosion-resistant polypropylene cable material of the present application, polypropylene, composite flame retardant and heat-conducting filler are first premixed, and then dicumyl peroxide is introduced as a free radical initiator; in the mixing process, dicumyl peroxide is decomposed by heat to generate active free radicals, which attack the tertiary carbon atoms on the polypropylene backbone to form polypropylene radicals; these radicals can react with the carbon-carbon double bonds in the maleic anhydride structure introduced in the composite flame retardant and the carbon-carbon double bonds in the 3,5-di-tert-butyl-4-hydroxycinnamic acid thioester grafted on the surface of the heat-conducting filler through previous modification, to form a chemical bond between polypropylene, composite flame retardant and heat-conducting filler; this not only enhances the interfacial bonding force between the composite flame retardant and the heat-conducting filler and the non-polar matrix of polypropylene, but also effectively prevents the agglomeration and phase separation of the fillers during processing and use, achieving uniform dispersion and stable anchoring of the functional components in the matrix.

[0034] The boron nitride in the heat-conductive filler is covalently connected with the graphene oxide through silane coupling agents, the rigid two-dimensional sheet layers thereof can be effectively inserted between the layers of the graphene oxide, significantly increasing the interlayer spacing thereof, weakening the interlayer π-π interaction and van der Waals force, thereby inhibiting the stacking and re-aggregation of the graphene oxide in the compounding process, allowing the graphene oxide to be uniformly dispersed in the polypropylene matrix in the form of single layers or few layers, fully exerting the advantages of high in-plane thermal conductivity of the graphene oxide, and the graphene oxide and the boron nitride cooperating to build a heat-conductive network penetrating through the three-dimensional space: both of them are high-thermal-conductivity insulating materials, the sheet layers thereof are overlapped and expanded in the matrix, forming an efficient phonon transmission channel, significantly reducing the interfacial thermal resistance between the filler-matrix and the filler-filler, thereby greatly improving the overall thermal conductivity of the cable material; the good thermal conductivity helps the cable to quickly dissipate the Joule heat generated by the conductor to the outside during operation, reduces the internal temperature rise of the insulation layer, slows down the thermal aging, and improves the current-carrying capacity and service life.

[0035] In addition, the uniform dispersion and chemical grafting of the filler also significantly improve the mechanical properties of the material. On the one hand, the three-dimensional heat-conductive network plays a physical reinforcing role in the matrix, which can effectively transmit stress and hinder crack propagation; on the other hand, the covalent bonding between polypropylene and the filler enhances the interfacial adhesion strength, allowing external forces to be efficiently transmitted to the high-modulus filler phase through the interface, thereby improving the mechanical properties of the material; especially under long-term thermal-mechanical coupling service conditions, the good thermal conductivity reduces the accumulation of internal thermal stress, further maintaining the mechanical properties of the material. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to make the content of the present application more easily understood, the present application will be further described in detail below according to specific embodiments and in conjunction with the accompanying drawings, in which

[0037] Figure 1 The structure diagram of the corrosion-resistant polypropylene insulated cable of an embodiment of the present application.

[0038] The reference signs in the drawings are: reinforcing core 1, electrical unit 2, conductor 2-1, conductor shielding layer 2-2, insulation layer 2-3, metal shielding layer 2-4, wrapping layer 3, inner sheath layer 4, armored layer 5, outer sheath layer 6 DETAILED DESCRIPTION

[0039] In order to better understand the above technical solutions, the above technical solutions will be described in detail below in conjunction with the drawings and specific embodiments of the specification.

[0040] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0041] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0042] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0043] In the description of the embodiments of the present application, it should be understood that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly understood by those skilled in the art, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0044] In the description of the embodiments of the present application, it should also be noted that, unless otherwise explicitly specified and limited, the terms "arrangement", "installation", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances. The present application will be further described below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and cannot limit the protection scope of the present application.

[0045] The hydroxyl N-alkoxy hindered amine is Tinuvin® 152 of BASF.

[0046] The plasticizer is triisooctyl phosphite.

[0047] The lubricant is calcium stearate.

[0048] The ultraviolet absorber is ultraviolet absorber UV-531.

[0049] The nucleating agent is talc.

[0050] The amino silane coupling agent is gamma-aminopropyl triethoxysilane; the mercapto silane coupling agent is mercapto propyl trimethoxysilane.

[0051] Hydroxylated hexagonal boron nitride: 200 nm diameter hexagonal boron nitride nanosheets are uniformly dispersed in a 4 mol / L sodium hydroxide solution, then heated and stirred at 90°C for 18 h, after the reaction, centrifuged, washed, and dried to obtain hydroxylated boron nitride, wherein the ratio of hexagonal boron nitride nanosheets to sodium hydroxide solution is 0.4 g: 100 mL.

[0052] Example 1

[0053] As Figure 1 A preparation process of a corrosion-resistant polypropylene insulated cable, comprising the following preparation steps:

[0054] A1. Preparation of the electrical unit 2: an aluminum plastic composite tape is wrapped outside the conductor 2-1 to form a conductor shielding layer 2-2, and a high-temperature 150°C radiation cross-linking flame-retardant polyolefin insulation material is extruded and wrapped outside the conductor shielding layer 2-2 to form an insulation layer 2-3, and an aluminum foil Mylar tape is wrapped outside the insulation layer 2-3 to obtain a metal shielding layer 2-4;

[0055] A2. Three electrical units 2 are arranged symmetrically around the center of the reinforcing core 1 to obtain a cable core;

[0056] A3. The wrapping layer 3 is wrapped outside the cable core, and the coverage rate is 15%;

[0057] A4. The corrosion-resistant polypropylene cable material is extruded outside the wrapping layer 3 to obtain an inner sheath layer 4;

[0058] A5. The galvanized steel wire braid is wrapped outside the inner sheath layer 4 to obtain an armor layer 5;

[0059] A6. The corrosion-resistant polypropylene cable material is extruded outside the armor layer 5 to obtain an outer sheath layer 6.

[0060] The preparation steps of the corrosion-resistant polypropylene cable material are as follows:

[0061] B1. Each raw material component is weighed and dosed according to the corresponding mass fraction: 70 mass parts of polypropylene, 30 mass parts of POE, 10 mass parts of plasticizer, 18 mass parts of composite flame retardant, 4 mass parts of thermal conductive filler, 1 mass part of lubricant, 0.2 mass parts of ultraviolet absorber, and 0.1 mass parts of nucleating agent;

[0062] B2. The weighed polypropylene, composite flame retardant, and thermal conductive filler were mixed and put into a 175℃ internal mixer for 15 minutes, then 0.17 parts by mass of dicumyl peroxide was added and mixed for another 15 minutes, then POE and maleic anhydride grafted polypropylene were added and melt blended for 10 minutes, then plasticizer, lubricant, ultraviolet absorber, and nucleating agent were added and melt blended for another 10 minutes, and then the mixture was put into a twin-screw extruder for extrusion and granulation, with 7 temperature zones from the feeding port to the die of the extruder, and the temperatures of the barrel segments were as follows: 180℃ for zone I, 185℃ for zone II, 190℃ for zone III, 190℃ for zone IV, 200℃ for zone V, 200℃ for zone VI, and 190℃ for zone VII. The screw rotation speed was set to 140 r / min. The cut granules were dried in a vacuum oven at 50℃ for 24 hours to obtain the corrosion-resistant polypropylene cable material.

[0063] The preparation method of the composite flame retardant is as follows: hydroxyl N-alkoxy hindered amine, cyanuric chloride, and acetonitrile were mixed, the mass / volume ratio of hydroxyl N-alkoxy hindered amine to acetonitrile was 1g:90mL, and stirring was performed at 0℃ until dissolution, then a solution of triethylamine in acetonitrile with a mass / volume ratio of 1g:100mL was added dropwise, and the reaction was continued for 3 hours to obtain a mixed solution A, wherein the molar ratio of hydroxyl N-alkoxy hindered amine, cyanuric chloride, and triethylamine was 1:1:1; cyanuric chloride, 4-hydroxymethyl-1-oxo-1-phospha-2,6,7-trioxa- bicyclo[2.2.2]octane, and acetonitrile were mixed, stirring was performed at 0℃ until dissolution, then triethylamine was added dropwise, and the reaction was continued for 3 hours to obtain a mixed solution B, wherein the molar ratio of cyanuric chloride, 4-hydroxymethyl-1-oxo-1-phospha-2,6,7-trioxa-bicyclo[2.2.2]octane, and triethylamine was 1:1:1; the mass / volume ratio of cyanuric chloride to acetonitrile was 1g:15mL; the mixed solution A and the mixed solution B were mixed uniformly, then ethylenediamine and 1 / 2 triethylamine were added dropwise after the temperature was raised to 55℃, and N-(2-aminoethyl) maleimide was added and the reaction was continued for 3 hours, then the temperature was raised to the reflux temperature, the remaining triethylamine was added dropwise and the reaction was continued for 3 hours, after the reaction was completed, the solvent was removed by suction filtration, the product was washed with deionized water three times, and then dried to obtain the composite flame retardant, wherein the molar ratio of ethylenediamine, N-(2-aminoethyl) maleimide, and triethylamine was 0.7:0.3:2; and the molar ratio of hydroxyl N-alkoxy hindered amine, 4-hydroxymethyl-1-oxo-1-phospha-2,6,7-trioxa-bicyclo[2.2.2]octane, and ethylenediamine was 0.003:1:1.

[0064] The preparation method of the heat-conducting filler is as follows: 0.5 parts by mass of graphene oxide is added into N,N-dimethylformamide in a mass volume ratio of 1 g: 300 mL and ultrasonically dispersed for 4 h, then 18 parts by mass of amino silane coupling agent and 0.8 parts by mass of dicyclohexyl carbodiimide are added, and under stirring, the reaction is carried out at 68 ℃ for 11 h. After that, the obtained reaction liquid is subjected to vacuum filtration treatment through a PVDF filter membrane, and the solid is collected. The obtained solid is washed several times with tetrahydrofuran and anhydrous ethanol. After washing, the solid and 18 parts by mass of mercapto silane coupling agent are re-dispersed in 250 parts by mass of ethanol, and then 25 parts by mass of deionized water and 4 parts by mass of acetic acid are added. After stirring at room temperature for 50 min, 0.2 parts by mass of hydroxylated boron nitride is added, and then the reaction is carried out at 75 ℃ for 5 h. The obtained solid is then collected by vacuum filtration and washing with ethanol and deionized water several times and dried. Then the dried solid is dispersed in 150 parts by mass of cyclohexane, and then 20 parts by mass of 3,5-di-tert-butyl-4-hydroxy cinnamic acid and 0.4 parts by mass of p-toluene sulfonic acid are added. Then the mixture is heated to 78 ℃ under stirring for 9 h. The cyclohexane is recovered by distillation under reduced pressure. The obtained solid is washed with saturated sodium bicarbonate solution, and then washed with water until neutral and dried to obtain the heat-conducting filler.

[0065] Example 2

[0066] The preparation process of the corrosion-resistant polypropylene insulated cable of Example 2 is the same as that of Example 1, except that:

[0067] The preparation steps of the corrosion-resistant polypropylene cable material are as follows:

[0068] B1. The raw material components are weighed and prepared according to the corresponding mass fraction: 80 parts by mass of polypropylene, 20 parts by mass of POE, 13 parts by mass of plasticizer, 20 parts by mass of composite flame retardant, 5 parts by mass of heat-conducting filler, 1.3 parts by mass of lubricant, 0.4 parts by mass of ultraviolet absorber, and 0.3 parts by mass of nucleating agent.

[0069] B2. The weighed polypropylene, composite flame retardant, and heat-conducting filler are mixed and put into a banbury mixer at 180 ℃ for 20 min. Then 0.2 parts by mass of dicumyl peroxide is added and the mixing is continued for 20 min. Then POE and maleic anhydride grafted polypropylene are melt blended for 15 min. Then plasticizer, lubricant, ultraviolet absorber, and nucleating agent are added and melt blended for 16 min. Then the mixture is put into a twin-screw extruder for extrusion and granulation. The temperature of the extruder is set to 7 intervals from the feeding port to the die: 180 ℃ for zone I, 185 ℃ for zone II, 190 ℃ for zone III, 190 ℃ for zone IV, 200 ℃ for zone V, 200 ℃ for zone VI, and 190 ℃ for zone VII. The screw speed is set to 140 r / min. The cut granules are dried in a vacuum oven at 50 ℃ for 24 h to obtain the corrosion-resistant polypropylene cable material.

[0070] The preparation method of the composite flame retardant is as follows: hydroxyl N-alkoxy hindered amine, tricyanamid chloride and acetonitrile are mixed, the mass-volume ratio of hydroxyl N-alkoxy hindered amine to acetonitrile is 1g:100mL, stirring at 5℃ until dissolution, then drop 1g:500mL acetonitrile solution of triethylamine, continue to react for 4h, to obtain mixture A, wherein the molar ratio of hydroxyl N-alkoxy hindered amine, tricyanamid chloride and triethylamine is 1:1:1; tricyanamid chloride, 4-hydroxymethyl-1-oxo-1-phospha-2,6,7-trioxa- bicyclo[2.2.2]octane and acetonitrile are mixed, stirring at 5℃ until dissolution, then drop triethylamine, continue to react for 4h, to obtain mixture B, wherein the molar ratio of tricyanamid chloride, 4-hydroxymethyl-1-oxo-1-phospha-2,6,7-trioxa-bicyclo[2.2.2]octane and triethylamine is 1:1:1; the mass-volume ratio of tricyanamid chloride to acetonitrile is 1g:20mL; mixture A and mixture B are mixed uniformly, then drop ethylenediamine and 1 / 2 triethylamine after heating to 55℃, and add N-(2-aminoethyl) maleimide to continue to react for 4h, then heat to reflux temperature, continue to drop the remaining triethylamine to react for 4h, after the reaction is completed, remove the solvent by suction filtration, wash with deionized water for three times, dry to obtain the composite flame retardant, wherein the molar ratio of ethylenediamine, N-(2-aminoethyl) maleimide and triethylamine is 0.7:0.3:2; wherein the feeding molar ratio of hydroxyl N-alkoxy hindered amine, 4-hydroxymethyl-1-oxo-1-phospha-2,6,7-trioxa-bicyclo[2.2.2]octane and ethylenediamine is 0.005:1:1.005.

[0071] The preparation method of the heat-conducting filler is as follows: 0.5 parts by mass of graphene oxide is added into N,N-dimethylformamide at a mass-volume ratio of 1g:400mL for ultrasonic dispersion for 5h, then 19 parts by mass of amino silane coupling agent and 1 part by mass of dicyclohexyl carbodiimide are added, and the reaction is carried out at 70℃ for 12h under stirring, after that, the obtained reaction liquid is treated by vacuum suction filtration through a PVDF filter membrane, and the collected solid is washed with tetrahydrofuran and anhydrous ethanol for several times, then the solid after washing is dispersed in 300 parts by mass of ethanol again with 19 parts by mass of mercapto silane coupling agent, 30 parts by mass of deionized water and 5 parts by mass of acetic acid are added, stirring at room temperature for 60min, then 0.25 parts by mass of hydroxylated boron nitride is added, and the reaction is carried out at 78℃ for 6h, then the obtained solid is collected by suction filtration and washing with ethanol and deionized water for several times and dried, then the dried solid is dispersed in 200 parts by mass of cyclohexane, then 25 parts by mass of 3,5-di-tert-butyl-4-hydroxycinnamic acid and 0.6 parts by mass of p-toluenesulfonic acid are added, then the reaction is carried out at 80℃ for 10h under stirring, and the cyclohexane is recovered by distillation under reduced pressure, the obtained solid is washed with saturated sodium bicarbonate solution, then washed with water until neutral, and dried to obtain the heat-conducting filler.

[0072] Example 3

[0073] The preparation process of the corrosion-resistant polypropylene insulated cable of Example 3 is the same as that of Example 1, except that:

[0074] The preparation steps of the corrosion-resistant polypropylene cable material are as follows:

[0075] B1. Weigh and mix the raw material components according to the corresponding mass fraction: 90 mass parts of polypropylene, 10 mass parts of POE, 15 mass parts of plasticizer, 20 mass parts of composite flame retardant, 5 mass parts of thermal conductive filler, 1.5 mass parts of lubricant, 0.7 mass parts of ultraviolet absorber, and 0.6 mass parts of nucleating agent;

[0076] B2. Mix the weighed polypropylene, composite flame retardant, and thermal conductive filler, and put them into a 185℃ internal mixer for 25min, then add 0.23 mass parts of dicumyl peroxide and continue to mix for 25min, then add POE, maleic anhydride grafted polypropylene and melt blend for 20min, then add plasticizer, lubricant, ultraviolet absorber, and nucleating agent and continue to melt blend for 20min, then put it into a twin-screw extruder for extrusion and granulation, with 7 temperature intervals from the feeding port to the die of the extruder: Zone I 180℃, Zone II 185℃, Zone III 190℃, Zone IV 190℃, Zone V 200℃, Zone VI 200℃, and Zone VII 190℃. The screw speed is set to 140r / min; the cut granules are dried in a vacuum oven at 50℃ for 24h to obtain the corrosion-resistant polypropylene cable material.

[0077] The preparation method of the composite flame retardant is as follows: mixing hydroxyl N-alkoxy hindered amine, tricyanamid chloride and acetonitrile, the mass-volume ratio of hydroxyl N-alkoxy hindered amine to acetonitrile is 1g:100mL, stirring at 5℃ until dissolution, then adding dropwise acetonitrile solution of triethylamine with a mass-volume ratio of 1g:600mL, continuing to react for 5h to obtain a mixed solution A, wherein the molar ratio of hydroxyl N-alkoxy hindered amine, tricyanamid chloride and triethylamine is 1:1:1; mixing tricyanamid chloride, 4-hydroxymethyl-1-oxo-1-phospha-2,6,7-trioxa- bicyclo[2.2.2]octane and acetonitrile, stirring at 5℃ until dissolution, then adding dropwise triethylamine, continuing to react for 5h to obtain a mixed solution B, wherein the molar ratio of tricyanamid chloride, 4-hydroxymethyl-1-oxo-1-phospha-2,6,7-trioxa-bicyclo[2.2.2]octane and triethylamine is 1:1:1; the mass-volume ratio of tricyanamid chloride to acetonitrile is 1g:20mL; mixing the mixed solution A and the mixed solution B uniformly, then adding dropwise ethylenediamine and 1 / 2 triethylamine after warming to 55℃, and adding N-(2-aminoethyl) maleimide to continue to react for 5h, then warming to reflux temperature, continuing to add the remaining triethylamine to react for 5h, after the reaction is completed, removing the solvent by suction filtration, washing with deionized water for three times, and drying to obtain the composite flame retardant, wherein the molar ratio of ethylenediamine, N-(2-aminoethyl) maleimide and triethylamine is 0.8:0.2:2; wherein the feeding molar ratio of hydroxyl N-alkoxy hindered amine, 4-hydroxymethyl-1-oxo-1-phospha-2,6,7-trioxa-bicyclo[2.2.2]octane and ethylenediamine is 0.007:1:1.01.

[0078] The preparation method of the heat-conducting filler is as follows: 0.5 parts by mass of graphene oxide is added into N,N-dimethylformamide with a mass-volume ratio of 1g:500mL for ultrasonic dispersion for 6h, then 20 parts by mass of amino silane coupling agent and 1.2 parts by mass of dicyclohexyl carbodiimide are added, and the reaction is carried out at 72℃ for 13h under stirring, after that, the obtained reaction liquid is treated by vacuum suction filtration through a PVDF filter membrane, and the collected solid is washed with tetrahydrofuran and anhydrous ethanol for several times, then the solid after washing is dispersed in 350 parts by mass of ethanol again with 20 parts by mass of mercapto silane coupling agent, 35 parts by mass of deionized water and 6 parts by mass of acetic acid are added, stirring at room temperature for 70min, then 0.3 parts by mass of hydroxylated boron nitride is added, and the reaction is carried out at 80℃ for 7h, then the obtained solid is collected by suction filtration and washing with ethanol and deionized water for several times and dried, then the dried solid is dispersed in 250 parts by mass of cyclohexane, then 30 parts by mass of 3,5-di-tert-butyl-4-hydroxycinnamic acid and 0.8 parts by mass of p-toluenesulfonic acid are added, then the reaction is carried out at 82℃ for 11h under stirring, and the cyclohexane is recovered by distillation under reduced pressure, the obtained solid is washed with saturated sodium bicarbonate solution, then washed with water until neutral, and dried to obtain the heat-conducting filler.

[0079] Comparative Example 1

[0080] Comparative Example 1 differs from Example 2 in that the thermally conductive filler is only graphene oxide, and the other components and steps are the same as in Example 2.

[0081] Comparative Example 2

[0082] Comparative Example 2 differs from Example 2 in that the thermally conductive filler is only boron nitride, and the other components and steps are the same as in Example 2.

[0083] Comparative Example 3

[0084] Comparative Example 3 differs from Example 2 in that the thermally conductive filler is only graphene oxide and boron nitride in a mass ratio of 1:0.5, and the other components and steps are the same as in Example 2.

[0085] Comparative Example 4

[0086] Comparative Example 4 differs from Example 2 in that the corrosion-resistant polypropylene cable material mainly includes 80 parts by mass of polypropylene, 20 parts by mass of POE, 13 parts by mass of plasticizer, 5 parts by mass of thermally conductive filler, 1.3 parts by mass of lubricant, 0.4 parts by mass of ultraviolet absorber, and 0.3 parts by mass of nucleating agent; the other components and steps are the same as in Example 2.

[0087] Comparative Example 5

[0088] Comparative Example 5 differs from Example 2 in that the corrosion-resistant polypropylene cable material mainly includes 80 parts by mass of polypropylene, 20 parts by mass of POE, 13 parts by mass of plasticizer, 20 parts by mass of composite flame retardant, 1.3 parts by mass of lubricant, 0.4 parts by mass of ultraviolet absorber, and 0.3 parts by mass of nucleating agent; the other components and steps are the same as in Example 2.

[0089] Effect Example

[0090] Table 1 below is the performance test results of the corrosion-resistant polypropylene cable material and the corrosion-resistant polypropylene insulated cable of Examples 1-3 and Comparative Examples 1-5:

[0091] Table 1

[0092]

[0093] As can be seen from Table 1, the corrosion-resistant polypropylene cable material prepared in Examples 1-3 has good corrosion resistance, thermal conductivity, flame retardancy, thermal oxidative aging resistance, and mechanical properties, and thus the corrosion-resistant polypropylene insulated cable has good corrosion resistance, heat dissipation, flame retardancy, thermal oxidative aging resistance, and mechanical properties.

[0094] The difference between Comparative Example 1 and Example 2 is that only graphene oxide is used as the heat-conducting filler, and the corrosion resistance, heat conductivity, flame retardancy, thermal oxidative aging resistance and mechanical properties of the prepared corrosion-resistant polypropylene cable material are weak.

[0095] The difference between Comparative Example 2 and Example 2 is that only boron nitride is used as the heat-conducting filler, and the corrosion resistance, heat conductivity, flame retardancy, thermal oxidative aging resistance and mechanical properties of the prepared corrosion-resistant polypropylene cable material are weak.

[0096] The difference between Comparative Example 3 and Example 2 is that only graphene oxide and boron nitride with a mass ratio of 1:0.5 are used as the heat-conducting filler, and the corrosion resistance, heat conductivity, flame retardancy, thermal oxidative aging resistance and mechanical properties of the prepared corrosion-resistant polypropylene cable material are weak.

[0097] The difference between Comparative Example 4 and Example 2 is that the corrosion-resistant polypropylene cable material does not add a composite flame retardant, and the flame retardancy and thermal oxidative aging resistance of the prepared corrosion-resistant polypropylene cable material are weak.

[0098] The difference between Comparative Example 5 and Example 2 is that the corrosion-resistant polypropylene cable material does not add a conductive filler, and the corrosion resistance, heat conductivity, flame retardancy, thermal oxidative aging resistance and mechanical properties of the prepared corrosion-resistant polypropylene cable material are weak.

[0099] In summary, when the composite flame retardant and the heat-conducting filler are added together in the corrosion-resistant polypropylene cable material of the present application, the composite flame retardant and the heat-conducting filler synergistically act, and the flame retardancy and thermal oxidative aging resistance of the corrosion-resistant polypropylene cable material are optimal.

[0100] The above specific examples further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A corrosion-resistant polypropylene insulated cable, characterized in that, The cable core comprises, from the inside out, a wrapping layer (3), an inner sheath layer (4), an armor layer (5), and an outer sheath layer (6); the cable core comprises a reinforcing core (1) and at least two electrical units (2) symmetrically arranged around the reinforcing core (1); the electrical unit (2) comprises, from the inside out, a conductor (2-1), a conductor shielding layer (2-2), an insulation layer (2-3), and a metal shielding layer (2-4); both the inner and outer sheath layers are made of corrosion-resistant polypropylene cable material. The corrosion-resistant polypropylene cable material mainly comprises, by weight, 70-90 parts polypropylene, 10-30 parts POE, 10-15 parts plasticizer, 18-20 parts composite flame retardant, 4-5 parts thermally conductive filler, 1-1.5 parts lubricant, 0.2-0.7 parts ultraviolet absorber, and 0.1-0.6 parts nucleating agent. The composite flame retardant is prepared from cyanuric chloride, 4-hydroxymethyl-1-oxo-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane, hydroxy N-alkoxy hindered amine, ethylenediamine, and N-(2-aminoethyl)maleimide as raw materials.

2. The corrosion-resistant polypropylene insulated cable according to claim 1, characterized in that, The thermally conductive filler is prepared from graphene oxide, silane coupling agent, boron nitride, and 3,5-di-tert-butyl-4-hydroxycinnamic acid.

3. The corrosion-resistant polypropylene insulated cable according to claim 2, characterized in that, The silane coupling agents include aminosilane coupling agents and mercaptosilane coupling agents.

4. A manufacturing process for a corrosion-resistant polypropylene insulated cable as described in any one of claims 1 to 3, characterized in that, The preparation steps include the following: A1. Preparation of electrical unit (2); A2. Arrange at least two electrical units (2) around the reinforcing core (1) to obtain the cable core; A3. Wrap the cladding around the outside of the cable core (3); A4. The corrosion-resistant polypropylene cable material is extruded over the wrapping layer (3) to obtain the inner sheath layer (4). A5. The inner sheath layer (4) is covered with an outer armor layer (5); A6. The corrosion-resistant polypropylene cable material is extruded over the armor layer (5) to obtain the outer sheath layer (6).

5. The manufacturing process of the corrosion-resistant polypropylene insulated cable according to claim 4, characterized in that, The preparation steps of the corrosion-resistant polypropylene cable material are as follows: B1. Weigh and mix each raw material component according to the corresponding mass proportions; B2. Mix the weighed polypropylene, composite flame retardant, and thermally conductive filler, and mix them in a mixer at 175~185℃ for 15~25 minutes. Then add 0.17~0.23 parts by weight of dicumyl peroxide and continue mixing for 15~25 minutes. Then add POE and maleic anhydride-grafted polypropylene and melt blend for 10~20 minutes. Next, add plasticizer, lubricant, ultraviolet absorber, and nucleating agent and continue melt blending for 10~20 minutes. Then put it into a twin-screw extruder for extrusion granulation to obtain corrosion-resistant polypropylene cable material.

6. The manufacturing process of the corrosion-resistant polypropylene insulated cable according to claim 5, characterized in that, The preparation method of the composite flame retardant is as follows: A hydroxyl N-alkoxy hindered amine, cyanuric chloride, and acetonitrile are mixed, with a mass-to-volume ratio of hydroxyl N-alkoxy hindered amine to acetonitrile of 1 g: 90-100 mL. The mixture is stirred at 0-5°C until dissolved. Then, a triethylamine acetonitrile solution with a mass-to-volume ratio of 1 g: 100-600 mL is added dropwise, and the reaction continues for 3-5 hours to obtain mixture A. The mixture contains hydroxyl N-alkoxy hindered amine, cyanuric chloride, and acetonitrile. The molar ratio of triethylamine is 1:1:1; cyanuric chloride, 4-hydroxymethyl-1-oxo-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane, and acetonitrile are mixed and stirred at 0-5℃ until dissolved. Then, triethylamine is added dropwise, and the reaction continues for 3-5 hours to obtain mixture B, wherein the molar ratio of cyanuric chloride, 4-hydroxymethyl-1-oxo-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane, and triethylamine is 1:1:

1. The ratio of cyanuric chloride to acetonitrile is 1:1:1; the mass-to-volume ratio of cyanuric chloride to acetonitrile is 1g:15~20mL; mix mixture A and mixture B thoroughly, heat to 55℃, then add ethylenediamine and 1 / 2 triethylamine dropwise, followed by N-(2-aminoethyl)maleimide and continue the reaction for 3~5h. Then heat to reflux temperature and continue adding the remaining triethylamine dropwise for 3~5h. After the reaction is complete, filter to remove the solvent, wash three times with deionized water, and dry. A composite flame retardant was obtained, wherein the molar ratio of ethylenediamine, N-(2-aminoethyl)maleimide, and triethylamine was (0.7~0.8):(0.2~0.3):2; and the molar ratio of hydroxy N-alkoxy hindered amine, 4-hydroxymethyl-1-oxo-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane, and ethylenediamine was (0.003~0.007):1:(1~1.01).

7. The manufacturing process of the corrosion-resistant polypropylene insulated cable according to claim 5, characterized in that, The preparation method of the thermally conductive filler is as follows: 0.5 parts by mass of graphene oxide are added to N,N-dimethylformamide at a mass-to-volume ratio of 1g:300-500mL and ultrasonically dispersed for 4-6 h. Then, 18-20 parts by mass of aminosilane coupling agent and 0.8-1.2 parts by mass of dicyclohexylcarbodiimide are added, and the mixture is reacted at 68-72℃ for 11-13 h under stirring. Afterward, the reaction solution is vacuum filtered through a PVDF filter membrane, and the solid is collected. The solid is then washed multiple times with tetrahydrofuran and anhydrous ethanol. After washing, the solid and 18-20 parts by mass of mercaptosilane coupling agent are redispersed in 250-350 parts by mass of ethanol. Then, 25-35 parts by mass of deionized water and 4-6 parts by mass of acetic acid are added, and the mixture is stirred at room temperature for 50-70 min. Then, 0.2-0.3 parts by mass of hydroxylated boron nitride are added, and the mixture is reacted at 75-80℃ for 5-7 h. Then, the reaction proceeds sequentially... The solid was collected by filtration and washing several times with ethanol and deionized water and dried. The dried solid was then dispersed in 150-250 parts by mass of cyclohexane, followed by the addition of 20-30 parts by mass of 3,5-di-tert-butyl-4-hydroxycinnamic acid and 0.4-0.8 parts by mass of p-toluenesulfonic acid. The mixture was then heated to 78-82°C under stirring and reacted for 9-11 hours. The cyclohexane was recovered by vacuum distillation. The obtained solid was washed with saturated sodium bicarbonate solution, then washed with water until neutral and dried to obtain the thermally conductive packing.

8. The manufacturing process of the corrosion-resistant polypropylene insulated cable according to claim 4, characterized in that, The armor layer (5) is woven from galvanized steel wire.

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