Preparation method of insulated halogen-free low-smoke fire-resistant cable

Abstract

The invention discloses a preparation method of an insulating halogen-free low-smoke fire-resistant cable, and belongs to the technical field of cables, the control cable comprises a core wire, the core wire comprises a conductor and an insulating layer extruded on the outer side of the conductor, and the insulating layer is made of flame-retardant crosslinked polyethylene; the flame-retardant crosslinked polyethylene comprises the following raw materials in parts by weight. In order to solve the problem that a large amount of dense smoke is generated during cable combustion, the halogen-free flame retardant is selected in the cable, so that the cable is more environment-friendly and safer, and the flame-retardant requirement is met. The halogen-free flame retardant disclosed by the invention does not generate an agglomeration effect, is better in dispersity, can better cope with fatigue fracture and inhibit the problems caused by water branches, and improves the electrical resistance of the material.

Description

Technical Field

[0001] The invention belongs to the technical field of cables, and in particular relates to a method for preparing an insulated halogen-free, low-smoke, fire-resistant cable. Background Art

[0002] The basic structure of the cable consists of four parts: the core, the insulation layer, the shielding layer and the protective layer. The core is the conductive part of the cable, which is used to transmit electrical energy; the insulation layer is to electrically isolate the cores of different phases from each other to ensure the transmission of electrical energy; the protective layer is to protect the control cable from the invasion of external impurities and moisture, and to prevent external forces from directly damaging the power cable. The interior of the cable body is easily damaged by external forces, especially halogen-containing materials such as the insulation layer and the sheath layer. Once a fire occurs, the halogen produces a large amount of thick smoke, and releases corrosive halogen acid gases when burning. In addition to endangering the human body, it will also cause damage to the equipment. As the service life increases, the outer shell of the cable is easy to break, or when bent, it is easy to squeeze the internal conductor and deform it, affecting the performance. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method for preparing an insulated halogen-free, low-smoke, fire-resistant cable to solve the problem of generating a large amount of thick smoke when the cable burns.

[0004] The purpose of the present invention can be achieved through the following technical solutions: A method for preparing an insulated halogen-free, low-smoke, fire-resistant cable is prepared by the following steps: S1. Weigh the insulating layer material according to the formula. The insulating layer material is made of flame-retardant cross-linked polyethylene. Stir it evenly at a temperature of 20-30°C. After mixing, add it into an extruder. Extrude the insulating layer material onto the conductor surface on the extruder. Then perform irradiation cross-linking to form an insulating layer to obtain a core wire. S2. Twist several core wires into a cable core, and coat the outer surface of the cable core with a polyester tape wrapping layer and a sheath layer in sequence to obtain an insulated halogen-free, low-smoke, fire-resistant cable.

[0005] Furthermore, the flame-retardant cross-linked polyethylene comprises the following raw materials in parts by weight: 100 parts of low-density polyethylene, 25-28 parts of halogen-free flame retardant, 0.2-0.5 parts of antioxidant, and 2.2-3 parts of benzophenone photoinitiator.

[0006] The present invention uses a halogen-free flame retardant to reduce the generation of thick smoke and also does not generate halogen acid corrosive gas that is harmful to human health.

[0007] Furthermore, the halogen-free flame retardant is prepared by the following steps: Octaepoxy cage-shaped silsesquioxane, DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) and triphenylphosphine were mixed, heated to 120° C. and reacted for 2 hours to obtain a flame retardant component; Under ice-water bath conditions, flame retardant components, dichloromethane and triethylamine are mixed, and then 10-undecenyl chloroacid is added. After the addition, the temperature is raised to 20-30°C, stirred for reaction for 7 hours, washed with water, and concentrated under pressure to obtain a halogen-free flame retardant. The halogen-free flame retardant in the present invention is obtained by reacting the hydroxyl group and undecenyl chloroacid in the flame retardant component, wherein the raw materials of the flame retardant component are octaepoxy cage-shaped silsesquioxane and DOPO, and DOPO is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, which contains a PH bond in its structure, is extremely active to olefins, epoxy bonds and carbonyl groups, and can react to generate many derivatives.

[0008] Furthermore, the usage ratio of octaepoxy cage-shaped silsesquioxane, DOPO and triphenylphosphine is 14g:18g:0.1g; the usage ratio of flame retardant component, dichloromethane, triethylamine and 10-undecenyl chloroacid is 2g:40mL:0.8g:1.5g.

[0009] Furthermore, the benzophenone photoinitiator is prepared by the following steps: 4-Hydroxybenzophenone and stearic acid chloride are added to pyridine, and the mixture is heated to 25°C for 30 minutes under an ice-water bath, and then stirred for 16 hours. After the reaction is completed, water and ethyl acetate are added for extraction, and ethyl acetate is removed by decompression and concentration to obtain a benzophenone photoinitiator. Conventional small molecule photoinitiators have certain volatility, and there will be volatilization during the processing process. In the present invention, 4-hydroxybenzophenone is treated, and it is reacted with stearic acid chloride under the action of an acid-binding agent, pyridine, and an alkyl long chain is introduced. On the one hand, the molecular weight of the photoinitiator is increased, and the migration resistance of the photoinitiator is improved; on the other hand, the introduction of a long-chain alkyl makes the dispersibility of the photoinitiator better, and from the test results, it can be seen that the treated photoinitiator can improve the anti-puncture performance of the insulating layer.

[0010] Furthermore, the molar ratio of 4-hydroxybenzophenone to stearic acid chloride is 1:1, and the amount ratio of 4-hydroxybenzophenone to pyridine is 1 g:10 mL.

[0011] Furthermore, the antioxidant is one of antioxidant 1076, antioxidant 1035, and antioxidant 1010.

[0012] Furthermore, a plurality of core wires are coated with a polyester tape wrapping layer, the outer side of the wrapping layer is coated with a sheath layer, and a filling is provided between the insulating layer and the wrapping layer.

[0013] Furthermore, the conductor is a copper conductor.

[0014] Furthermore, the banburying temperature is 110-120°C, the banburying time is 6-8 minutes, and the extrusion temperature is 130-140°C.

[0015] Furthermore, the conditions for radiation cross-linking are: the radiation dose is 10-20 Mrd.

[0016] Beneficial effects of the present invention: In order to solve the problem of generating a large amount of thick smoke when the cable burns, the present invention uses a halogen-free flame retardant, which is more environmentally friendly and safe, and meets the flame retardant requirements. The flame retardant effect of the halogen-free flame retardant in the present invention is nitrogen-phosphorus synergistic, wherein phosphorus has the effect of catalyzing carbonization, and the Si-O bond in the molecule forms a Si-O bond, and the generated white combustion residue and carbide form a composite inorganic layer, which can prevent the volatiles generated by combustion from escaping, block oxygen from contacting the matrix, prevent the melt from dripping, and further improve the stability of the carbon layer, thereby achieving the purpose of flame retardancy.

[0017] Water tree growth is a form of cross-linked polyethylene aging, and it is a long electrothermal aging process. Water tree growth will further induce electrical tree growth, which will eventually lead to breakdown of the cable insulation layer. In the present invention, octaepoxy cage silsesquioxane is selected as the raw material. On the one hand, the main constituent element is Si, which can form a synergistic flame retardant system with DOPO. On the other hand, the octaepoxy cage silsesquioxane contains multiple reaction sites, and unsaturated alkyl long chains can be introduced in the subsequent reaction type to increase the cross-linking density of the material, form more three-dimensional network structures, improve the toughness of the material, prevent the generation of microcracks, and thus improve the fatigue fracture of the molecular chain of the cross-linked polyethylene under the action of the electric field force. At the same time, compared with the conventional technical means using nanomaterials, the halogen-free flame retardant in the present invention will not have agglomeration effect, has better dispersibility, can better deal with the problems of fatigue fracture and inhibit water tree growth, and improve the electrical resistance of the material. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] A method for preparing an insulated halogen-free, low-smoke, fire-resistant cable, comprising a core wire, the core wire comprising a conductor and an insulating layer extruded on the outside of the conductor, a plurality of core wires coated with a polyester tape wrapping layer, the outer side of the wrapping layer is coated with a sheath layer, and a filler is arranged between the insulating layer and the wrapping layer; the insulating layer material is made of flame-retardant cross-linked polyethylene, and the flame-retardant cross-linked polyethylene comprises the following raw materials by weight: 100 parts of low-density polyethylene, 25-28 parts of halogen-free flame retardant, 0.2-0.5 parts of antioxidant, and 2.2-3 parts of benzophenone photoinitiator. Low-density polyethylene (LLLDPE 324CNJ): Sabic.

[0020] Embodiment 1: This embodiment provides a halogen-free flame retardant, which is prepared by the following steps: Under nitrogen protection, 95.2g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 40g of 6% tetramethylammonium hydroxide aqueous solution and 450mL of isopropanol were mixed, stirred and reacted at 25°C for 5h. After the reaction, the solvent was removed by rotary evaporation, toluene was added to dissolve, washed with deionized water, dried over anhydrous magnesium sulfate, and 8g of 10% tetramethylammonium hydroxide aqueous solution was added. The temperature was raised and refluxed for 10h. After the reaction, octaepoxy cage-shaped silsesquioxane was obtained after washing, rotary evaporation and drying.

[0021] Octaepoxy cage silsesquioxane, DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) and triphenylphosphine were mixed, heated to 120°C and reacted for 2 hours to obtain a flame retardant component; the amount ratio of octaepoxy cage silsesquioxane, DOPO and triphenylphosphine was 14g:18g:0.1g; In an ice-water bath, the flame retardant component, dichloromethane and triethylamine were mixed, and then 10-undecenyl chloroacid was added. After the addition, the temperature was raised to 20°C, stirred for reaction for 7 hours, washed with water, and concentrated under pressure to obtain a halogen-free flame retardant. The amount ratio of the flame retardant component, dichloromethane, triethylamine and 10-undecenyl chloroacid was 2g:40mL:0.8g:1.5g.

[0022] Embodiment 2: This embodiment provides a benzophenone photoinitiator, which is prepared by the following steps: 4-Hydroxybenzophenone and stearic acid chloride were added to pyridine, and the mixture was kept in an ice-water bath for 30 minutes, then heated to 25°C and stirred for 16 hours. After the reaction, water and ethyl acetate were added for extraction, and the ethyl acetate was removed by concentration under reduced pressure to obtain a benzophenone photoinitiator. The molar ratio of 4-hydroxybenzophenone to stearic acid chloride was 1:1, and the amount ratio of 4-hydroxybenzophenone to pyridine was 1 g:10 mL.

[0023] Embodiment 3: This embodiment provides a method for preparing an insulated halogen-free, low-smoke, fire-resistant cable, which is prepared by the following steps: S1. Weigh the raw materials by weight: 100 parts of low-density polyethylene, 25 parts of the halogen-free flame retardant prepared in Example 1, 0.2 parts of antioxidant 1076, and 2.2 parts of benzophenone photoinitiator prepared in Example 2, stir them evenly at a temperature of 20°C, add them into an extruder after banburying, and extrude the insulating layer material onto the surface of the copper conductor on the extruder; then perform irradiation cross-linking with an irradiation dose of 10 Mrd to form an insulating layer and obtain a core wire; the banburying temperature is 110°C, the banburying time is 6 min; the extrusion temperature is 130°C; S2. A method for preparing an insulated halogen-free, low-smoke, fire-resistant cable is obtained by twisting a plurality of core wires into a cable core, and sequentially coating the outer surface of the cable core with a polyester tape wrapping layer and a sheath layer.

[0024] Embodiment 4: This embodiment provides a method for preparing an insulated halogen-free, low-smoke, fire-resistant cable, which is prepared by the following steps: S1. Weigh the raw materials by weight: 100 parts of low-density polyethylene, 28 parts of the halogen-free flame retardant prepared in Example 1, 0.3 parts of antioxidant 1076, and 2.8 parts of the benzophenone photoinitiator prepared in Example 2, stir them evenly at a temperature of 25° C., add them into an extruder after banburying, and extrude the insulating layer material onto the surface of the copper conductor on the extruder; then perform irradiation cross-linking with an irradiation dose of 20 Mrd to form an insulating layer and obtain a core wire; the banburying temperature is 120° C., the banburying time is 8 min; the extrusion temperature is 140° C.; S2. A method for preparing an insulated halogen-free, low-smoke, fire-resistant cable is obtained by twisting a plurality of core wires into a cable core, and sequentially coating the outer surface of the cable core with a polyester tape wrapping layer and a sheath layer.

[0025] Embodiment 5: This embodiment provides a method for preparing an insulated halogen-free, low-smoke, fire-resistant cable, which is prepared by the following steps: S1. Weigh the raw materials by weight: 100 parts of low-density polyethylene, 28 parts of the halogen-free flame retardant prepared in Example 1, 0.5 parts of antioxidant 1076, and 3 parts of the benzophenone photoinitiator prepared in Example 2, stir them evenly at a temperature of 30°C, add them into an extruder after banburying, and extrude the insulating layer material onto the surface of the copper conductor on the extruder; then perform irradiation cross-linking with an irradiation dose of 20 Mrd to form an insulating layer and obtain a core wire; the banburying temperature is 120°C, the banburying time is 8 min; the extrusion temperature is 140°C; S2. A method for preparing an insulated halogen-free, low-smoke, fire-resistant cable is obtained by twisting a plurality of core wires into a cable core, and sequentially coating the outer surface of the cable core with a polyester tape wrapping layer and a sheath layer.

[0026] Comparative Example 1: Compared with Example 5, this comparative example replaces the halogen-free flame retardant with ammonium polyphosphate, and the remaining raw materials and preparation process remain the same as those of Example 5.

[0027] Comparative Example 2: Compared with Comparative Example 1, the photoinitiator in this comparative example is replaced with 4-hydroxybenzophenone, and the other raw materials and preparation process remain the same as those in Comparative Example 1.

[0028] The performance test of the insulation layer in Example 3-Example 5 and Comparative Example 1-Comparative Example 2 was carried out. The limiting oxygen index was tested according to GB / T 2406.2-2009 standard. The sample size was 150×10×4 mm. 3 The vertical combustion test was carried out according to GB / T2408-2008 standard, and the sample size was 127×12.7×3.2 mm 3 The water needle electrode method was used to accelerate the aging experiment of water branches. The morphology of water branches was observed under an optical microscope, and the growth length and initiation probability of water branches were counted. The results are shown in Table 1: Table 1 As can be seen from Table 1, the amount of halogen-free flame retardant added in the present invention is small, and it can meet higher flame retardant performance. Compared with the conventional halogen-free flame retardant ammonium polyphosphate, it has better flame retardant performance. The reason may be that the different flame retardant elements in the flame retardant of the present invention have good synergy and meet the flame retardant requirements. According to the accelerated water tree aging experiment, the cable insulation layer in the present invention has stable breakdown resistance, and the photoinitiator has a certain improvement effect on the breakdown resistance. The reason may be that the photoinitiator is conducive to improving the dispersion effect between the raw materials, making the performance of each part of the material more uniform.

[0029] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0030] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an insulated halogen-free, low-smoke, fire-resistant cable, characterized in that: Prepared by the following steps: S1. Weigh the insulating layer material according to the formula. The insulating layer material is made of flame-retardant cross-linked polyethylene. Stir it evenly at a temperature of 20-30°C. After mixing, add it into an extruder. Extrude the insulating layer material onto the conductor surface on the extruder. Then perform irradiation cross-linking to form an insulating layer to obtain a core wire. S2. Twist several core wires into a cable core, and coat the outer surface of the cable core with a polyester tape wrapping layer and a sheath layer in sequence to obtain an insulated halogen-free, low-smoke, fire-resistant cable.

2. The method for preparing an insulated halogen-free, low-smoke, fire-resistant cable according to claim 1, characterized in that: The flame-retardant cross-linked polyethylene comprises the following raw materials in parts by weight: 100 parts of low-density polyethylene, 25-28 parts of halogen-free flame retardant, 0.2-0.5 parts of antioxidant, and 2.2-3 parts of benzophenone photoinitiator.

3. The method for preparing an insulated halogen-free, low-smoke, fire-resistant cable according to claim 2, characterized in that: Halogen-free flame retardants are prepared by the following steps: Octaepoxy cage-shaped silsesquioxane, DOPO and triphenylphosphine were mixed, heated to 120° C. and reacted for 2 hours to obtain a flame retardant component; In an ice-water bath, the flame retardant component, dichloromethane and triethylamine were mixed, and then 10-undecenyl chloroacid was added. After the addition, the temperature was raised to 20-30°C, stirred for reaction for 7 hours, washed with water, and concentrated under pressure to obtain a halogen-free flame retardant.

4. The method for preparing an insulated halogen-free, low-smoke, fire-resistant cable according to claim 3, characterized in that: The usage ratio of octaepoxy cage-shaped silsesquioxane, DOPO and triphenylphosphine is 14g:18g:0.1g; the usage ratio of flame retardant component, dichloromethane, triethylamine and 10-undecenyl chloroacid is 2g:40mL:0.8g:1.5g.

5. The method for preparing an insulated halogen-free, low-smoke, fire-resistant cable according to claim 2, characterized in that: The benzophenone photoinitiator is prepared by the following steps: 4-Hydroxybenzophenone and stearic acid chloride were added to pyridine, and the mixture was placed in an ice-water bath for 30 minutes. The mixture was then heated to 25° C. and stirred for 16 hours to obtain a benzophenone photoinitiator.

6. The method for preparing an insulated halogen-free, low-smoke, fire-resistant cable according to claim 5, characterized in that: The molar ratio of 4-hydroxybenzophenone to stearic acid chloride is 1:1, and the amount ratio of 4-hydroxybenzophenone to pyridine is 1 g:10 mL.

7. The method for preparing an insulated halogen-free, low-smoke, fire-resistant cable according to claim 2, characterized in that: The antioxidant is one of antioxidant 1076, antioxidant 1035 and antioxidant 1010.

8. The method for preparing an insulated halogen-free, low-smoke, fire-resistant cable according to claim 1, characterized in that: The mixing temperature is 110-120°C, the mixing time is 6-8min, and the extrusion temperature is 130-140°C.

9. The method for preparing an insulated halogen-free, low-smoke, fire-resistant cable according to claim 1, characterized in that: The conditions for radiation cross-linking are: radiation dose of 10-20 Mrd.

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