Preparation process and application of high temperature resistant and fireproof cable

Abstract

The invention discloses a preparation process and application of a high-temperature resistant and fireproof cable, belonging to the technical field of cable processing. The invention comprises the following steps: adding modified polypropylene, modified alumina, modified polysiloxane, copper sulfate pentahydrate and auxiliary additives into a twin-screw extruder, and melt-extruding them on the outside of an armored cable to obtain a high-temperature resistant and fireproof cable; the invention uses modified polypropylene as a base material, modified alumina and modified polysiloxane as reinforcing materials, and auxiliary additives as auxiliary agents to prepare a flame-retardant protective sheath material, and extruding the protective sheath material on the outside of the armored cable to obtain a high-temperature resistant and fireproof cable, thereby improving not only the high-temperature resistance and flame retardancy of the cable, but also the mechanical properties of the cable, making the cable more in line with the high demands of various industries for cables.

Description

Technical Field

[0001] The present invention relates to the technical field of cable processing, and in particular to a preparation process and application of a high-temperature resistant and fireproof cable. Background Art

[0002] With the continuous development of science and technology and the improvement of industrial demand, cables are widely used in many fields. Cables are usually composed of soft conductors and insulation layers. They have good bending, flexibility and the ability to adapt to complex environments. They are particularly suitable for occasions that require frequent movement or limited space.

[0003] In recent years, with the rise of automation, intelligence and green energy, the demand for cables has continued to grow, especially in the fields of robotics, smart homes, renewable energy, automotive electrification and industrial control systems. In order to meet higher safety, durability and environmental adaptability, the design and materials of cables are constantly innovating, such as the use of high-performance polyvinyl chloride, cross-linked polypropylene and low-smoke halogen-free materials to enhance their anti-aging, anti-interference, high temperature and corrosion resistance. In addition, with the increasing demand for power transmission and signal transmission, in order to ensure the efficient and stable operation of power equipment and information communication systems, the high temperature resistance and fire resistance of cables have also become a research hotspot.

[0004] Prior art CN115910456 B discloses a high temperature resistant fireproof cable and its preparation method, wherein a hydroxyl group and a quinoline ring structure are introduced into a polyethylene structure to obtain a modified polyethylene, and the modified polyethylene is mixed with 100-130 parts of a polyolefin resin, 20-25 parts of clay, 25-30 parts of talc, 8-10 parts of silica sol, and 17-19 parts of magnesium hydroxide.

[0005] After being evenly mixed with 3-8 parts of polyethylene wax, the mixture is added into a twin-screw extruder and granulated to obtain a low-smoke zero-halogen outer sheath. The outer surface of the annealed stranded copper conductor is successively coated with a mineral insulation layer and an insulating isolation layer to obtain a cable core. The outer surfaces of multiple cable cores are then filled to form a filling layer. Finally, the outer surface of the filling layer is successively coated with a mineral fireproof layer and a low-smoke zero-halogen outer sheath to obtain a high-temperature resistant and fire-resistant cable. The cable can work for a long time at an ambient temperature of 250°C and can also work for a short time at an ambient temperature of 1340°C in an emergency.

[0006] However, the above patent content is that after the modified polyethylene is prepared, the modified polyethylene is evenly mixed with polyolefin resin, clay, talc, silica sol, magnesium hydroxide and polyethylene wax, added to a twin-screw extruder, extruded and granulated to obtain a low-smoke halogen-free outer sheath. However, the outer sheath contains materials such as silica sol and polyolefin resin, which have poor compatibility with the modified polyethylene, which can easily lead to poor wear resistance of the outer sheath of the cable, thereby causing the outer sheath to be consumed too quickly, and the flame retardant performance and high temperature resistance of the cable need to be further improved.

[0007] In view of the technical defects in this aspect, a solution is now proposed. Summary of the Invention

[0008] The purpose of the present invention is to provide a preparation process of a high-temperature resistant and fire-resistant cable and its application, so as to solve the technical problem in the prior art that the high-temperature resistance, flame retardancy and mechanical properties of the cable need to be further improved.

[0009] The purpose of the present invention can be achieved by the following technical solution: A preparation process of a high temperature resistant fireproof cable comprises the following steps:

[0010] S1. Extruding insulating rubber onto the outside of the conductor to obtain a cable core;

[0011] S2. Using inorganic fiber as a filler, wrapping a plurality of parallel cable cores together with a wrapping tape, and then wrapping a soft metal armor layer around the wrapping tape layer to obtain a cable blank;

[0012] S3. Add modified polypropylene, modified alumina, modified polysiloxane, copper sulfate pentahydrate and auxiliary additives into a twin-screw extruder, melt-extrude them on the outside of the cable blank, and obtain a high-temperature resistant and fire-resistant cable.

[0013] Preparation reaction principle of high temperature resistant and fireproof cable:

[0014] During the reaction process, copper sulfate pentahydrate releases water under heating conditions, causing the siloxy groups in modified alumina and modified polysiloxane to be hydrolyzed into silanols, which undergo esterification reaction with modified polypropylene containing maleic anhydride to form chemical crosslinks to obtain a flame-retardant protective sheath material. The flame-retardant protective sheath material is melt-extruded onto the outside of the armored cable to obtain a high-temperature resistant and fire-resistant cable.

[0015] Furthermore, in step S1, the insulating rubber is one or more of polyvinyl chloride rubber and butyl rubber; in step S2, the inorganic fiber is one or more of glass fiber and ceramic fiber, the wrapping tape is phlogopite tape, and the soft metal is one or more of soft copper wire, steel wire, and aluminum alloy wire.

[0016] Furthermore, in step S3, the amount ratio of the modified polypropylene, modified alumina, modified polysiloxane, copper sulfate pentahydrate and auxiliary additives is 20-30g:5-10g:15-20g:4-6g:2-4g, and the auxiliary additives are composed of a lubricant, an antioxidant, and a filler in a weight ratio of 1:1:2. The lubricant is one or more of zinc stearate and polyethylene wax, the antioxidant is one or more of antioxidant 6PPD, antioxidant MB, and antioxidant MBI, and the filler is one or more of carbon black, montmorillonite, and aluminum hydroxide. The temperatures of the eight temperature zones of the twin-screw extruder from the feed port to the discharge port are 160°C, 160°C, 165, 165°C, 170°C, 170°C, 180°C, and 180°C, respectively. The main engine speed of the twin-screw extruder is 80-120rpm and the pressure is 100-150bar.

[0017] Furthermore, the preparation method of the modified polypropylene is as follows: maleic anhydride, toluene, dicumyl peroxide and styrene are placed in a reaction kettle, heated to 80-90°C, stirred for 0.5-1h, added with polypropylene, kept warm for reaction for 3-5h, and post-treated to obtain the modified polypropylene.

[0018] The preparation reaction formula of modified polypropylene is:

[0019]

[0020] The reaction principle for preparing modified polypropylene is:

[0021] During the reaction, styrene and polypropylene are initiated by dicumyl peroxide to generate nucleophilic free radicals. Styrene has higher reactivity than maleic anhydride and is first grafted onto the polypropylene chain. Due to the conjugation effect of the aromatic ring, it can polymerize to form more stable free radicals. Maleic anhydride has strong charge-absorbing properties and can undergo charge transfer complexation reaction with charge-rich styrene to generate electron transfer complexes.

[0022] Furthermore, the amount ratio of maleic anhydride, acetone, dicumyl peroxide, styrene and polypropylene is 1.5-2g:100-150mL:0.5-1g:1.5-2g:20-30g, and the post-processing step includes: after the reaction is completed, transferring the reaction liquid to a rotary evaporator at a temperature of 50-60°C, rotating until no liquid is extracted, adding the solid to a twin-screw extruder, melt-extruded, and cooled to obtain modified polypropylene.

[0023] Furthermore, the preparation method of the modified alumina comprises the following steps:

[0024] B1. Place alumina powder, KH-550, deionized water, and ethanol in a reactor protected by a nitrogen atmosphere, heat to 90-110°C, and keep the temperature for 2-4 hours. Post-process to obtain amino aluminum oxide;

[0025] Preparation reaction principle of amino aluminum oxide:

[0026] During the reaction, the silicon-oxygen bond of KH-550 is hydrolyzed into silanol under the action of deionized water, which condenses with the hydroxyl groups on the surface of alumina to obtain aminosilane coupling agent-modified aminoalumina.

[0027] B2. Hexachlorocyclotriphosphazene, amine aluminum oxide and N,N-dimethylformamide are placed in a reaction kettle, heated to 135-145° C., kept warm for 0.5-1 hour, and post-treated to obtain modified aluminum oxide.

[0028] Reaction principle for preparing modified alumina:

[0029] During the reaction, the amino group in aminoaluminum oxide has nucleophilicity and attacks the chloride ion in hexachlorocyclotriphosphazene, causing nucleophilic substitution to obtain modified alumina.

[0030] Furthermore, in step B1, the amount ratio of the alumina powder, KH-550, deionized water and ethanol is 5-10g:2-4g:10-15mL:60-80mL, and the post-treatment step includes: after the reaction is completed, filtering with suction, transferring the filter cake to a drying oven at a temperature of 55-65°C, and drying to constant weight to obtain amino aluminum oxide; in step B2, the amount ratio of the hexachlorocyclotriphosphazene, amino aluminum oxide and N,N-dimethylformamide is 2-3g:5-8g:80-100mL, and the post-treatment step includes: after the reaction is completed, filtering with suction, transferring the filter cake to a drying oven at a temperature of 45-55°C, and drying to constant weight to obtain modified alumina.

[0031] Furthermore, the preparation method of the modified polysiloxane comprises the following steps:

[0032] C1. Place octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane, potassium hydroxide solution and toluene in a reactor protected by nitrogen atmosphere, heat to 85-105° C., keep warm for 1-2 hours, and post-treat to obtain hydroxyl-terminated polysiloxane;

[0033] The preparation reaction formula of hydroxyl-terminated polysiloxane is:

[0034]

[0035] The preparation reaction principle of hydroxyl-terminated polysiloxane is:

[0036] Tetramethyltetravinylcyclotetrasiloxane and octamethylcyclotetrasiloxane are hydrolyzed and ring-opened under the action of high temperature and potassium hydroxide solution, and then condensed to form a long polysiloxane chain with trifluoropropyl modification. The deionized water in the potassium hydroxide acts as a capping agent and condenses with the long polysiloxane chain molecules to form a hydroxyl end-capping modification to prepare a hydroxyl-terminated polysiloxane.

[0037] C2. Place hydroxy-terminated polysiloxane, 4-dimethylaminopyridine, benzoin dimethyl ether and toluene in a reactor protected by a nitrogen atmosphere, heat to 45-55° C., turn on the ultraviolet lamp, add ethyl mercaptoacetate, keep the temperature for reaction for 1-2 hours, and post-treat to obtain a modified polysiloxane precursor;

[0038] The preparation reaction formula of modified polysiloxane precursor is:

[0039]

[0040] The preparation reaction principle of modified polysiloxane precursor is:

[0041] Under ultraviolet light, benzoin dimethyl ether decomposes into free radicals, which react with the olefin double bond of the terminal hydroxyl polysiloxane to form new free radicals through free radical addition reaction. The nucleophilicity of the thiol group in ethyl mercaptoacetate increases under the catalysis of 4-dimethylaminopyridine, and the olefin double bond free radical of the terminal hydroxyl polysiloxane undergoes nucleophilic substitution to obtain a modified polysiloxane precursor.

[0042] C3. Place the modified polysiloxane precursor, 3-isocyanatepropyltriethoxysilane, triethylamine and toluene in a reaction kettle, heat to 120-130° C., keep the temperature for reaction for 3-5 hours, and post-treat to obtain the modified polysiloxane.

[0043] The preparation reaction formula of modified polysiloxane is:

[0044]

[0045] Where:

[0046] The preparation reaction principle of modified polysiloxane is:

[0047] During the reaction, the hydroxyl group of the modified polysiloxane precursor carries a lone electron pair, which attacks the isocyanate group of 3-isocyanatepropyltriethoxysilane to form a chemical crosslink to obtain a modified polysiloxane modified with triethylsilane.

[0048] Further, in step C1, the concentration of the potassium hydroxide solution is 15-20wt%, the amount ratio of the octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane, potassium hydroxide solution and toluene is 3-6g:5-10g:1-1.5mL:90-150mL, and the post-treatment step comprises: after the reaction is completed, the temperature of the reaction system is reduced to room temperature, the liquid is allowed to stand, the organic phase is washed with ethanol 1-2 times, and then transferred to a rotary evaporator at a temperature of 95-105°C, and vacuum rotary evaporation is performed until no liquid is extracted to obtain a terminal hydroxyl polysiloxane; in step C2, the amount ratio of the terminal hydroxyl polysiloxane, 4-dimethylaminopyridine, benzoin dimethyl ether, toluene and ethyl mercaptoacetate is 3-6 g:0.5-1g:0.3-0.6g:90-150mL:2-4g, the post-processing step comprises: after the reaction is completed, filtering, washing the filter cake with ethanol 1-2 times and then drying, transferring it to a drying oven at a temperature of 95-105°C, and drying it to constant weight to obtain a hydroxy-terminated polysiloxane; in step C3, the amount ratio of the modified polysiloxane precursor, 3-isocyanatepropyltriethoxysilane, triethylamine and toluene is 8-10g:2-3g:0.5-1g:100-200mL, and the post-processing step comprises: after the reaction is completed, adding ethanol to the reactor, raising the temperature of the reactor to 100-120°C, and distilling under reduced pressure until no liquid is produced to obtain a modified polysiloxane.

[0049] The present invention also proposes an application of a high-temperature resistant and fireproof cable, and the cable prepared by the above-mentioned preparation process of a high-temperature resistant and fireproof cable is applied to low-voltage power distribution.

[0050] The present invention has the following beneficial effects:

[0051] 1. In the process of preparing a high-temperature resistant and fire-proof cable, the present invention prepares a flame-retardant protective sheath material by using modified polypropylene as a base material, modified alumina and modified polysiloxane as reinforcing materials, and auxiliary additives as auxiliary agents. By introducing styrene and maleic anhydride into polypropylene, the aromatic ring has stability, thereby improving the mechanical strength and heat resistance of polypropylene. The anhydride structure provided by maleic anhydride provides active sites for further synthesis of flame-retardant protective sheath materials, thereby improving the mechanical properties and high-temperature resistance of the cable. Hexachlorocyclotriphosphazene is modified on the surface of alumina by a silane coupling agent, thereby improving the high-temperature resistance and flame retardancy of alumina, further improving the flame retardancy and heat resistance of the synthesized cable. The silicon-oxygen bond in polysiloxane has good thermal stability. By modification with 3-isocyanatepropyltriethoxysilane, its compatibility with other materials in the preparation of the flame-retardant protective sheath material is improved, thereby improving the mechanical properties and heat resistance of the cable.

[0052] 2. In the process of preparing a high-temperature resistant and fire-resistant cable, the present invention prepares polypropylene having styrene blocks and maleic anhydride blocks through a free radical polymerization reaction. The aromatic ring structure of styrene improves the mechanical properties and heat stability of polypropylene. The modified polypropylene has anhydride groups introduced by maleic anhydride. When the flame-retardant protective sheath material is subsequently prepared, the anhydride groups react with the silanols after the modified alumina and the hydrolysis of the modified polysiloxane to form a three-dimensional network cross-linked structure, further improving the tensile strength and high-temperature resistance of the cable. The polysiloxane itself has excellent high-temperature resistance and can remain stable at high temperatures. The ester group is introduced through the ene click reaction to improve the low-temperature elasticity of the cable sheath. Modification with a silane coupling agent can introduce a triethylsilane structure into the polysiloxane, providing reaction sites, further improving the mechanical strength and high-temperature resistance of the cable. The polysiloxane can release less harmful gases in the event of a fire and form a protective inorganic silicate coating at high temperatures. This coating can effectively isolate oxygen, thereby preventing the spread of flames, and can further improve the fire resistance and flame retardant effect of the cable in high-temperature fires.

[0053] 3. In the process of preparing high-temperature resistant and fire-proof cables, the present invention performs silane modification on alumina powder, modifies amino groups on its surface, and further forms chemical crosslinks with hexachlorocyclotriphosphazene, thereby enhancing the mechanical strength of the cable. Hexachlorocyclotriphosphazene itself is a cyclic compound containing phosphorus, which has a good flame retardant effect at high temperatures. When a fire occurs, hexachlorocyclotriphosphazene releases phosphide, which can react with free radicals in the flame, reduce the activity of the free radicals, and inhibit the spread of the flame. Alumina and hexachlorocyclotriphosphazene form a high-temperature resistant protective layer at high temperatures, further isolating oxygen, thereby slowing down the combustion process. The flame-retardant protective sheath material prepared with modified polypropylene, modified alumina, modified polysiloxane, copper sulfate pentahydrate and auxiliary additives can form a complex three-dimensional structural crosslinking between the materials, further improving the mechanical strength and stability of the cable. DETAILED DESCRIPTION

[0054] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0055] The conductor material of the cable used in the present invention is oxygen-free copper, and its performance meets the requirements of GB / T 3956-2008 standard.

[0056] The alumina powder used in the present invention was purchased from Yangzhou Zhongtianli New Materials Co., Ltd., with the product number ZTL-WAO.

[0057] Example 1

[0058] This embodiment provides a method for preparing modified alumina for high-temperature resistant and fire-resistant cables, comprising the following steps:

[0059] A1. Preparation of Aluminum Oxide

[0060] Weigh: 50 g of alumina powder, 20 g of KH-550, 50 mL of deionized water, and 600 mL of ethanol, place them in a reactor protected by a nitrogen atmosphere, heat to 90°C, and keep the reaction for 2 hours. After the reaction is completed, filter and transfer the filter cake to a drying oven at 55°C and dry it to constant weight to obtain amino aluminum oxide.

[0061] A2. Preparation of modified alumina

[0062] Weigh 20 g of hexachlorocyclotriphosphazene, 50 g of amine aluminum oxide, and 800 mL of N,N-dimethylformamide and place them in a reactor. Heat to 135°C and keep warm for 0.5 h. After the reaction is completed, filter and transfer the filter cake to a drying oven at 45°C and dry it to constant weight to obtain modified alumina.

[0063] Example 2

[0064] This embodiment provides a method for preparing modified alumina for high-temperature resistant and fire-resistant cables, comprising the following steps:

[0065] A1. Preparation of Aluminum Oxide

[0066] Weigh 70 g of alumina powder, 30 g of KH-550, 700 mL of deionized water, and 700 mL of ethanol, place them in a reactor protected by a nitrogen atmosphere, heat to 100°C, and keep warm for 3 hours. After the reaction is completed, filter and transfer the filter cake to a drying oven at 60°C and dry to constant weight to obtain amino aluminum oxide.

[0067] A2. Preparation of modified alumina

[0068] Weigh 25 g of hexachlorocyclotriphosphazene, 70 g of amine aluminum oxide, and 900 mL of N,N-dimethylformamide and place them in a reactor. Heat to 140°C and keep warm for 1 hour. After the reaction is completed, filter and transfer the filter cake to a drying oven at 55°C and dry it to constant weight to obtain modified alumina.

[0069] Example 3

[0070] This embodiment provides a method for preparing modified alumina for high-temperature resistant and fire-resistant cables, comprising the following steps:

[0071] A1. Preparation of Aluminum Oxide

[0072] Weigh: 100 g of alumina powder, 40 g of KH-550, 100 mL of deionized water, and 800 mL of ethanol, place them in a reactor protected by a nitrogen atmosphere, heat to 110°C, and keep warm for 4 hours. After the reaction is completed, filter and transfer the filter cake to a drying oven at 65°C and dry it to constant weight to obtain amino aluminum oxide.

[0073] A2. Preparation of modified alumina

[0074] Weigh: 30 g of hexachlorocyclotriphosphazene, 80 g of amine aluminum oxide and 1000 mL of N,N-dimethylformamide, place them in a reactor, heat to 145°C, and keep the temperature for reaction for 1 hour. After the reaction is completed, filter and transfer the filter cake to a drying oven at a temperature of 55°C and dry it to constant weight to obtain modified alumina.

[0075] Example 4

[0076] This embodiment provides a method for preparing a modified polysiloxane for a high-temperature resistant and fire-resistant cable, comprising the following steps:

[0077] B1. Preparation of hydroxyl-terminated polysiloxane

[0078] Weigh: 30 g of octamethylcyclotetrasiloxane, 50 g of tetramethyltetravinylcyclotetrasiloxane, 10 mL of 15 wt% potassium hydroxide solution and 900 mL of toluene, place them in a reactor protected by a nitrogen atmosphere, heat to 85 ° C, and keep the reaction for 2 hours. After the reaction is completed, the temperature of the reaction system is lowered to room temperature, and the liquid is separated by standing. The organic phase is washed twice with ethanol and transferred to a rotary evaporator at a temperature of 95 ° C. and evaporated under reduced pressure until no liquid is recovered to obtain a hydroxy-terminated polysiloxane;

[0079] B2. Preparation of modified polysiloxane precursor

[0080] Weigh: 30 g of hydroxy-terminated polysiloxane, 5 g of 4-dimethylaminopyridine, 3 g of benzoin dimethyl ether, and 900 mL of toluene, place them in a reactor protected by a nitrogen atmosphere, heat to 45°C, turn on the ultraviolet lamp, add 20 g of ethyl mercaptoacetate, and keep the reaction for 2 hours. After the reaction is complete, filter, wash the filter cake twice with ethanol, drain it, transfer it to a drying oven at 95°C, and dry it to constant weight to obtain a modified polysiloxane precursor;

[0081] B3. Preparation of modified polysiloxane

[0082] Weigh: 80 g of modified polysiloxane precursor, 20 g of 3-isocyanatepropyltriethoxysilane, 5 g of triethylamine and 1000 mL of toluene, place them in a reactor, heat to 120 ° C, and keep warm for 3 hours. After the reaction is completed, ethanol is added to the reactor, the temperature of the reactor is raised to 100 ° C, and vacuum distillation is carried out until no liquid is extracted to obtain modified polysiloxane.

[0083] Example 5

[0084] This embodiment provides a method for preparing a modified polysiloxane for a high-temperature resistant and fire-resistant cable, comprising the following steps:

[0085] B1. Preparation of hydroxyl-terminated polysiloxane

[0086] Weigh: 40 g of octamethylcyclotetrasiloxane, 70 g of tetramethyltetravinylcyclotetrasiloxane, 12 mL of 17 wt% potassium hydroxide solution and 1 L of toluene, place them in a reactor protected by a nitrogen atmosphere, heat to 95 ° C, and keep the reaction for 2 hours. After the reaction is completed, the temperature of the reaction system is lowered to room temperature, allowed to stand and separate, the organic phase is washed twice with ethanol, and then transferred to a rotary evaporator at a temperature of 100 ° C., and vacuum evaporated until no liquid is recovered to obtain terminal hydroxyl polysiloxane.

[0087] B2. Preparation of modified polysiloxane precursor

[0088] Weigh: 45 g of terminal hydroxyl polysiloxane, 7 g of 4-dimethylaminopyridine, 4 g of benzoin dimethyl ether and 1 L of toluene, place them in a reactor protected by a nitrogen atmosphere, heat to 50 ° C, turn on the ultraviolet lamp, add 30 g of ethyl mercaptoacetate, and keep warm for 2 hours. After the reaction is completed, filter, wash the filter cake with ethanol twice and then dry it, transfer it to a drying oven at a temperature of 100 ° C, and dry it to constant weight to obtain a modified polysiloxane precursor.

[0089] B3. Preparation of modified polysiloxane

[0090] Weigh: 90 g of modified polysiloxane precursor, 25 g of 3-isocyanatepropyltriethoxysilane, 7 g of triethylamine and 1700 mL of toluene, place them in a reactor, heat to 125 ° C, and keep warm for 4 hours. After the reaction is completed, ethanol is added to the reactor, the temperature of the reactor is raised to 110 ° C, and vacuum distillation is carried out until no liquid is extracted to obtain modified polysiloxane.

[0091] Example 6

[0092] This embodiment provides a method for preparing a modified polysiloxane for a high-temperature resistant and fire-resistant cable, comprising the following steps:

[0093] B1. Preparation of hydroxyl-terminated polysiloxane

[0094] Weigh: 60 g of octamethylcyclotetrasiloxane, 100 g of tetramethyltetravinylcyclotetrasiloxane, 15 mL of 20 wt% potassium hydroxide solution and 1.5 L of toluene, place them in a reactor protected by a nitrogen atmosphere, heat to 105 ° C, and keep the reaction for 2 hours. After the reaction is completed, the temperature of the reaction system is lowered to room temperature, allowed to stand and separate, the organic phase is washed twice with ethanol, and then transferred to a rotary evaporator at a temperature of 105 ° C., and evaporated under reduced pressure until no liquid is recovered to obtain terminal hydroxyl polysiloxane.

[0095] B2. Preparation of modified polysiloxane precursor

[0096] Weigh: 60 g of terminal hydroxyl polysiloxane, 10 g of 4-dimethylaminopyridine, 6 g of benzoin dimethyl ether and 1.5 L of toluene, place them in a reactor protected by a nitrogen atmosphere, heat to 55 ° C, turn on the ultraviolet lamp, add 40 g of ethyl mercaptoacetate, and keep warm for 2 hours. After the reaction is completed, filter, wash the filter cake with ethanol twice and then dry it, transfer it to a drying oven at a temperature of 105 ° C, and dry it to constant weight to obtain a modified polysiloxane precursor.

[0097] B3. Preparation of modified polysiloxane

[0098] Weigh: 100 g of modified polysiloxane precursor, 30 g of 3-isocyanatepropyltriethoxysilane, 10 g of triethylamine and 2000 mL of toluene, place them in a reactor, heat to 130 ° C, and keep warm for 5 hours. After the reaction is completed, ethanol is added to the reactor, the temperature of the reactor is raised to 120 ° C, and distilled under reduced pressure until no liquid is extracted to obtain modified polysiloxane.

[0099] Example 7

[0100] This embodiment provides a method for preparing modified polypropylene for high temperature resistant and fireproof cables:

[0101] Weigh: 15 g of maleic anhydride, 1000 mL of toluene, 5 g of dicumyl peroxide and 15 g of styrene, place them in a reactor, heat to 80°C, stir for 0.5 h, add 200 g of polypropylene, and keep warm for 3 h. After the reaction is completed, transfer the reaction liquid to a rotary evaporator at 50°C, rotate until no liquid is extracted, add the solid to a twin-screw extruder, melt extrude, and cool to obtain modified polypropylene.

[0102] Example 8

[0103] This embodiment provides a method for preparing modified polypropylene for high temperature resistant and fireproof cables:

[0104] Weigh: 17 g of maleic anhydride, 1200 mL of toluene, 7 g of dicumyl peroxide and 17 g of styrene, place them in a reactor, heat to 85°C, stir for 7 hours, add 250 g of polypropylene, and keep warm for 4 hours. After the reaction is completed, transfer the reaction liquid to a rotary evaporator at a temperature of 55°C, rotate until no liquid is extracted, add the solid to a twin-screw extruder, melt extrude, and cool to obtain modified polypropylene.

[0105] Example 9

[0106] This embodiment provides a method for preparing modified polypropylene for high temperature resistant and fireproof cables:

[0107] Weigh: 20 g of maleic anhydride, 1500 mL of toluene, 10 g of dicumyl peroxide and 20 g of styrene, place them in a reactor, heat to 90°C, stir for 1 hour, add 300 g of polypropylene, and keep warm for 5 hours. After the reaction is completed, transfer the reaction liquid to a rotary evaporator at 60°C, rotate until no liquid is extracted, add the solid to a twin-screw extruder, melt extrude, and cool to obtain modified polypropylene.

[0108] Example 10

[0109] This embodiment provides a method for preparing a high-temperature resistant and fire-resistant cable, comprising the following steps:

[0110] S1. Preparation of cable core

[0111] Butyl rubber is extruded onto the outside of the conductor to obtain a cable core.

[0112] S2. Preparation of cable blank

[0113] The invention adopts ceramic fiber as filler and phlogopite tape to wrap several parallel cable cores together, and then a soft copper wire armor layer is wrapped around the outer surface of the wrapping tape layer to obtain a cable blank.

[0114] S3. Preparation of high temperature resistant and fireproof cables

[0115] Zinc stearate, antioxidant 6PPD and montmorillonite are mixed uniformly in a weight ratio of 1:1:2 to obtain an auxiliary additive;

[0116] Weigh by weight: 200 parts of modified polypropylene prepared in Example 7, 50 parts of modified alumina prepared in Example 1, 150 parts of modified polysiloxane prepared in Example 4, 40 parts of copper sulfate pentahydrate and 20 parts of auxiliary additives and add them into a twin-screw extruder. The temperatures of the eight temperature zones of the twin-screw extruder from the feed port toward the discharge port are 160°C, 160°C, 165, 165°C, 170°C, 170°C, 180°C, and 180°C, respectively. The main engine speed of the twin-screw extruder is 100 rpm and the pressure is 125 bar. After melt extrusion, the materials are coated on the outside of the armored cable to obtain a high-temperature resistant and fire-resistant cable.

[0117] Example 11

[0118] This embodiment provides a method for preparing a high-temperature resistant and fire-resistant cable, comprising the following steps:

[0119] S1. Preparation of cable core

[0120] Butyl rubber is extruded onto the outside of the conductor to obtain a cable core.

[0121] S2. Preparation of cable blank

[0122] The invention adopts ceramic fiber as filler and phlogopite tape to wrap several parallel cable cores together, and then a soft copper wire armor layer is wrapped around the outer surface of the wrapping tape layer to obtain a cable blank.

[0123] S3. Preparation of high temperature resistant and fireproof cables

[0124] Zinc stearate, antioxidant 6PPD and montmorillonite are mixed uniformly in a weight ratio of 1:1:2 to obtain an auxiliary additive;

[0125] Weigh by weight: 250 parts of modified polypropylene prepared in Example 8, 70 parts of modified alumina prepared in Example 2, 170 parts of modified polysiloxane prepared in Example 5, 50 parts of copper sulfate pentahydrate and 30 parts of auxiliary additives are added to a twin-screw extruder. The temperatures of the eight temperature zones of the twin-screw extruder from the feed port toward the discharge port are 160°C, 160°C, 165, 165°C, 170°C, 170°C, 180°C, and 180°C, respectively. The main engine speed of the twin-screw extruder is 100 rpm and the pressure is 125 bar. After melt extrusion, the materials are coated on the outside of the armored cable to obtain a high-temperature resistant and fire-resistant cable.

[0126] Example 12

[0127] This embodiment provides a method for preparing a high-temperature resistant and fire-resistant cable, comprising the following steps:

[0128] S1. Preparation of cable core

[0129] Butyl rubber is extruded onto the outside of the conductor to obtain a cable core.

[0130] S2. Preparation of cable blank

[0131] The invention adopts ceramic fiber as filler and phlogopite tape to wrap several parallel cable cores together, and then a soft copper wire armor layer is wrapped around the outer surface of the wrapping tape layer to obtain a cable blank.

[0132] S3. Preparation of high temperature resistant and fireproof cables

[0133] Zinc stearate, antioxidant 6PPD and montmorillonite are mixed uniformly in a weight ratio of 1:1:2 to obtain an auxiliary additive;

[0134] Weigh by weight: 300 parts of modified polypropylene prepared in Example 9, 100 parts of modified alumina prepared in Example 3, 200 parts of modified polysiloxane prepared in Example 6, 60 parts of copper sulfate pentahydrate and 40 parts of auxiliary additives are added to a twin-screw extruder. The temperatures of the eight temperature sections of the twin-screw extruder from the feed port toward the discharge port are 160°C, 160°C, 165, 165°C, 170°C, 170°C, 180°C, and 180°C, respectively. The main engine speed of the twin-screw extruder is 100rpm and the pressure is 125bar. After melt extrusion, the extruder is coated on the outside of the armored cable to obtain a high-temperature resistant and fire-resistant cable.

[0135] Comparative Example 1

[0136] The difference between this comparative example and Example 12 is that when the modified alumina is prepared, no hexachlorocyclotriphosphazene is added in step A2.

[0137] Comparative Example 2

[0138] The difference between this comparative example and Example 12 is that the modified polysiloxane used is replaced by an equal amount of the hydroxyl-terminated polysiloxane in Example 6.

[0139] Comparative Example 3

[0140] The difference between this comparative example and Example 12 is that the modified polypropylene used is replaced by an equal amount of the polypropylene in Example 9.

[0141] Performance testing:

[0142] The flame retardant properties of the test samples in Examples 10-12 and Comparative Examples 1-3 were tested with reference to the standard GB / T 19666-2019 "General Rules for Flame Retardant and Fire Resistant Wires, Cables or Optical Cables";

[0143] The mechanical strength of the test specimens in Examples 10-12 and Comparative Examples 1-3 was tested with reference to the standard GB / T 17737.316-2018 "Coaxial communication cables Part 1-316: Mechanical test methods - Maximum tensile strength test of cables";

[0144] The toughness of the test specimens in Examples 10-12 and Comparative Examples 1-3 was tested with reference to the standard JB / T 10696.3-2007 "Test methods for mechanical and physical and chemical properties of wires and cables - Part 3: Bending test";

[0145] The high temperature resistance of the test specimens in Examples 10-12 and Comparative Examples 1-3 after treatment at 200° C. was tested with reference to the standard GB / T 2951.42-2008 "General test methods for insulation and sheathing materials of electric and optical cables - Part 42: Specific test methods for polyethylene and polypropylene mixtures; Tensile strength and elongation at break test after high temperature treatment; Winding test after high temperature treatment; Winding test after air heat aging; Determination of mass increase; Long-term thermal stability test; Copper-catalyzed oxidative degradation test method."

[0146] The wear resistance of the test specimens in Examples 10-12 and Comparative Examples 1-3 was tested with reference to the standard GB / T 17737.324-2018 "Coaxial Communication Cables Part 1-324: Mechanical Test Methods - Cable Abrasion Resistance Test". The specific test data are shown in Table 1:

[0147] Table 1. Performance test data of samples

[0148]

[0149] Data Analysis:

[0150] Analysis and comparison of the data in the above table show that the flame retardant performance of the high-temperature resistant and fire-resistant cable prepared by the present invention reaches V-0, the tensile strength reaches 203 MPa, the thermal resistivity reaches 3.15 K·m / W, the blade scraping cycle number is 75, and after treatment at 200°C, the cable is not cracked and the tensile strength is 191 MPa.

[0151] By comparing the data of Example 12 and Comparative Example 1, it can be found that the flame retardant properties and high temperature resistance of the cable are significantly reduced, indicating that in the process of preparing the high temperature resistant and fireproof cable of the present invention, the aluminum oxide powder is silane-modified, and amino groups are modified on its surface, which further form chemical crosslinks with hexachlorocyclotriphosphazene, thereby enhancing the mechanical strength of the cable. Hexachlorocyclotriphosphazene itself is a cyclic compound containing phosphorus, which has a good flame retardant effect at high temperatures. When a fire occurs, hexachlorocyclotriphosphazene releases phosphide, which can react with free radicals in the flame, reduce the activity of the free radicals, and inhibit the spread of the flame. Aluminum oxide and hexachlorocyclotriphosphazene form a high temperature resistant protective layer at high temperatures, further isolating oxygen, thereby slowing down the combustion process, and further improving the high temperature resistance and flame retardant and fireproof properties of the cable.

[0152] By comparing the data of Example 12 and Comparative Example 2, it can be found that the mechanical strength, flame retardant properties and high temperature resistance of the cable are significantly reduced, indicating that in the process of preparing high-temperature resistant and fire-resistant cables, the present invention introduces polysiloxane into the cable protective sheath material through chemical crosslinking via a silane coupling agent, thereby generating a three-dimensional network cross-linked structure and further improving the tensile strength and high temperature resistance of the cable.

[0153] By comparing the data of Example 12 and Comparative Example 3, it can be found that the mechanical strength, flame retardant properties and high temperature resistance of the cable are significantly reduced, indicating that in the process of preparing the high temperature resistant and fireproof cable of the present invention, a polypropylene having styrene blocks and maleic anhydride blocks is prepared by free radical polymerization reaction, and the aromatic ring structure of styrene improves the mechanical properties and heat stability of the polypropylene. The anhydride groups introduced by maleic anhydride on the modified polypropylene react with the silanols obtained by hydrolysis of modified alumina and modified polysiloxane to generate a three-dimensional network cross-linked structure when the flame retardant protective sheath material is subsequently prepared, thereby further improving the tensile strength and high temperature resistance of the cable.

[0154] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A preparation process for a high temperature resistant and fireproof cable, characterized in that: The following steps are involved: S1. Extruding insulating rubber onto the outside of the conductor to obtain a cable core; S2. Using inorganic fiber as a filler, wrapping a plurality of parallel cable cores together with a wrapping tape, and then wrapping a soft metal armor layer around the wrapping tape layer to obtain a cable blank; S3, adding modified polypropylene, modified alumina, modified polysiloxane, copper sulfate pentahydrate and auxiliary additives into a twin-screw extruder, and melt-extruding them onto the outside of the cable blank to obtain a high-temperature resistant and fire-resistant cable; The auxiliary additives are composed of a lubricant, an anti-aging agent, and a filler in a weight ratio of 1:1:2, and the filler is one or more of carbon black, montmorillonite, and aluminum hydroxide; The preparation method of the modified polypropylene comprises: placing maleic anhydride, toluene, dicumyl peroxide and styrene in a reaction kettle, heating to 80-90° C., stirring for 0.5-1 hour, adding polypropylene, keeping the temperature for reaction for 3-5 hours, and post-processing to obtain the modified polypropylene; The preparation method of the modified alumina comprises the following steps: B1. Place alumina powder, KH-550, deionized water, and ethanol in a reactor protected by a nitrogen atmosphere, heat to 90-110°C, and react for 2-4 hours. Post-process to obtain aminoalumina. B2. Hexachlorocyclotriphosphazene, aluminum oxide, and N,N-dimethylformamide are placed in a reaction kettle, heated to 135-145° C., kept warm for 0.5-1 hour, and post-treated to obtain modified aluminum oxide; The preparation method of the modified polysiloxane comprises the following steps: C1. Place octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane, potassium hydroxide solution and toluene in a reactor protected by nitrogen atmosphere, heat to 85-105° C., keep warm for 1-2 hours, and post-treat to obtain hydroxyl-terminated polysiloxane; C2. Place hydroxy-terminated polysiloxane, 4-dimethylaminopyridine, benzoin dimethyl ether and toluene in a reactor protected by a nitrogen atmosphere, heat to 45-55° C., turn on the ultraviolet lamp, add ethyl mercaptoacetate, keep the temperature for reaction for 1-2 hours, and post-treat to obtain a modified polysiloxane precursor; C3. Place the modified polysiloxane precursor, 3-isocyanatepropyltriethoxysilane, triethylamine and toluene in a reaction kettle, heat to 120-130° C., keep the temperature for reaction for 3-5 hours, and post-treat to obtain the modified polysiloxane.

2. The preparation process of a high temperature resistant and fireproof cable according to claim 1, characterized in that: In step S1, the insulating rubber is one or more of polyvinyl chloride rubber and butyl rubber; in step S2, the inorganic fiber is one or more of glass fiber and ceramic fiber, the wrapping tape is phlogopite tape, and the soft metal is one or more of soft copper wire, steel wire, and aluminum alloy wire; in step S3, the amount ratio of the modified polypropylene, modified alumina, modified polysiloxane, copper sulfate pentahydrate, and auxiliary additives is 20-30g:5-10g:15-20g:4-6g:2-4g, the lubricant is one or more of zinc stearate and polyethylene wax, and the antioxidant is one or more of antioxidant 6PPD, antioxidant MB, and antioxidant MBI.

3. The preparation process of a high temperature resistant and fireproof cable according to claim 1, characterized in that: The usage ratio of maleic anhydride, acetone, dicumyl peroxide, styrene and polypropylene is 1.5-2g:100-150mL:0.5-1g:1.5-2g:20-30g.

4. The preparation process of a high temperature resistant and fireproof cable according to claim 1, characterized in that: In step B1, the ratio of the alumina powder, KH-550, deionized water and ethanol is 5-10 g: 2-4 g: 5-10 mL: 60-80 mL; in step B2, the ratio of the hexachlorocyclotriphosphazene, amine aluminum oxide and N,N-dimethylformamide is 2-3 g: 5-8 g: 10-15 mL: 80-100 mL.

5. The preparation process of a high temperature resistant and fireproof cable according to claim 1, characterized in that: In step C1, the concentration of the potassium hydroxide solution is 15-20wt%, and the amount ratio of the octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane, potassium hydroxide solution and toluene is 3-6g:5-10g:1-1.5mL:90-150mL; in step C2, the amount ratio of the hydroxy-terminated polysiloxane, 4-dimethylaminopyridine, benzoin dimethyl ether, toluene and ethyl mercaptoacetate is 3-6g:0.5-1g:0.3-0.6g:90-150mL:2-4g; in step C3, the amount ratio of the modified polysiloxane precursor, 3-isocyanatopropyltriethoxysilane, triethylamine and toluene is 8-10g:2-3g:0.5-1g:100-200mL.

6. An application of a high temperature resistant and fireproof cable, characterized in that: The cable prepared by the preparation process of a high-temperature resistant and fire-resistant cable described in claims 1-5 is applied to low-voltage power distribution.

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