Flame-retardant insulating shield applied to safety protection of fuse and preparation method of flame-retardant insulating shield

Abstract

The invention discloses a flame-retardant insulating shield applied to safety protection of a fuse and a preparation method of the flame-retardant insulating shield, and belongs to the technical field of fuse shields, and the flame-retardant insulating shield specifically comprises the following raw materials in parts by weight: 80-100 parts of hybrid polyolefin, 20-30 parts of flame-retardant particles, 3-5 parts of a plasticizer, 1-2 parts of an antioxidant, 2-3 parts of a heat stabilizer and 2-3 parts of a lubricant. The preparation method comprises the following steps: preparing modified polysiloxane through siloxane hydrolysis by taking zinc sulfide particles as a carrier flame-retardant filler, hybridizing modified polyolefin with a light stabilizer structure in a chain segment by taking the modified polysiloxane as a chain extender, so as to prepare hybrid polyolefin, and carrying out melt blending on the hybrid polyolefin and auxiliary materials, so as to obtain the flame-retardant composite material. And the flame-retardant insulating fuse shield is prepared.

Description

Technical Field

[0001] The present invention relates to the technical field of fuse shields, and particularly to a flame-retardant and insulating shield for fuse safety protection and a preparation method thereof. Background Art

[0002] The safety protection of fuses is crucial for power systems, and flame-retardant and insulating shields play a key role in preventing fire and electric shock accidents. The flame-retardant property requires materials to effectively inhibit combustion, such as using phosphorus-based, nitrogen-based or silicon-based flame retardants to ensure that the flame extinguishes quickly and without dripping. The insulation property requires the shield to have high dielectric strength, low dielectric loss and good moisture resistance to prevent electric breakdown and leakage accidents. Common materials include glass fiber-reinforced polymers, silicone rubber and fluoroplastics to ensure their stability at high temperatures and in harsh environments. The current technological development trend mainly focuses on environmentally friendly flame retardants, nano-scale insulating coatings and intelligent protection materials to improve the durability and safety of the shield.

[0003] The prior art CN110660626A discloses a preparation method of a fuse insulation protection sleeve. Sodium alkylbenzene sulfonate is taken as a dispersant and dissolved in deionized water, and then calcium fluoride is added thereto. After calcium fluoride is stirred and dispersed, a calcium fluoride dispersion is obtained. Polyvinyl alcohol is added to the calcium fluoride dispersion, and heated and stirred to obtain a viscous dispersion. The thermally conductive insulating particles are treated with a coupling agent, and the treated thermally conductive insulating particles are added to the viscous dispersion obtained in the previous step, and stirred and mixed to make the thermally conductive insulating particles uniformly dispersed in the viscous dispersion, obtaining a thermally conductive filling material. Phenolic resin and polyvinyl chloride are uniformly mixed and then heated and stirred. After the phenolic resin and polyvinyl chloride are melted and mixed, a mixed resin is obtained, wherein the phenolic resin accounts for 10%-80% of the weight of the mixed resin. A flame retardant and the thermally conductive filling material are added to the mixed resin, and stirred evenly to obtain a mixed material, wherein the weight ratio of the mixed resin, calcium fluoride and the thermally conductive insulating particles is 10:1.5-3.5:2-4. The mixed material is extruded through a screw extruder to form a sheet-like insulating layer. Thermally conductive insulating particles are added to the silicone pressure-sensitive adhesive, and evenly mixed. Then the thermally conductive layer is immersed therein so that the surface of the thermally conductive layer is evenly coated with a layer of silicone pressure-sensitive adhesive. The thermally conductive layer is arranged between two insulating layers, and pressed to make the three-layer structure composite together. After the solvent volatilizes, it is dried to obtain a high-thermal-conductivity insulating composite material.

[0004] However, the above patent content involves preparing a thermally conductive filler material, uniformly mixing it with phenolic resin and polyvinyl chloride, heating and stirring, melting and mixing the phenolic resin and polyvinyl chloride to obtain a mixed resin, and then mixing it with a flame retardant material to obtain a high thermally conductive insulating composite material for a protective cover. However, for the main materials of the above materials, phenolic resin and polyvinyl chloride, their light transmittance is poor, making it difficult to effectively observe the state of the fuse inside the protective cover, increasing the difficulty of later maintenance of the fuse, reducing the safety of maintenance, and the thermally conductive material quickly transfers the heat inside the fuse to the inside. Moreover, the flame retardant material used cannot form an expanded carbon layer or a ceramized barrier, resulting in the inability to effectively block the flame, and the flame retardant performance of the material needs to be further improved. Summary of the Invention

[0005] The purpose of the present invention is to provide a flame retardant insulating protective cover for fuse safety protection and its preparation method, aiming to solve the technical problem that the flame retardant performance and light transmittance of the fuse protective cover in the prior art need to be further improved.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A flame retardant insulating protective cover for fuse safety protection, comprising the following raw material components by weight: 80 - 100 parts of hybrid polyolefin, 20 - 30 parts of flame retardant particles, 3 - 5 parts of plasticizer, 1 - 2 parts of antioxidant, 2 - 3 parts of heat stabilizer, and 2 - 3 parts of lubricant.

[0007] Further, the plasticizer is one or more of dibutyl phthalate, dioctyl phthalate, and dioctyl terephthalate; the antioxidant is one or two of tris(2,4 - di - tert - butylphenyl) phosphate and cetyl - 3,5 - di - tert - butyl - 4 - hydroxybenzoate; the heat stabilizer is one or more of lead stearate, tribasic lead sulfate, and epoxidized soybean oil; the lubricant is one or more of stearic acid, polyethylene wax, and paraffin.

[0008] Further, the preparation method of the hybrid polyolefin includes the following steps:

[0009] A1. Add allyl methyl carbonate, epoxy butene, maleic anhydride, and tetrahydrofuran to a reaction kettle. After the temperature of the reaction kettle rises to 40 - 60°C, add azobisisobutyronitrile to the reaction kettle, keep warm and stir for 2 - 3 h, and then perform post - treatment to obtain polyolefin;

[0010] A2. Add polyolefin and N,N - dimethylformamide to a reaction kettle. When the temperature of the reaction kettle rises to 40 - 60°C, keep warm and stir for 10 - 15 min, then add triethylamine and 2 - hydroxy - 4 - benzyloxybenzophenone to the reaction kettle, keep warm and react for 30 - 40 min, and then perform post - treatment to obtain modified polyolefin;

[0011] A3. Add the modified polyolefin and N,N-dimethylacetamide into a reaction kettle. Raise the temperature of the reaction kettle to 40 - 50 °C. After heat preservation and stirring for 10 - 15 min, add pyridine and modified polysiloxane into the reaction kettle, continue heat preservation and stirring at 40 - 60 °C, and then perform post-treatment to obtain the hybrid polyolefin.

[0012] The reaction equation for preparing the hybrid polyolefin is:

[0013]

[0014] The reaction principle for preparing the hybrid polyolefin is as follows: Under the catalysis of a free radical initiator and high temperature, allyl methyl carbonate, epoxybutene, and maleic anhydride undergo a free radical addition reaction to form a long-chain structure. And under the catalysis of an alkaline condition, a part of the epoxy groups in the organic chain segment undergo a ring-opening reaction to generate free radicals, which react with 2-hydroxy-4-benzyloxybenzophenone to prepare the modified polyolefin. Finally, under the catalysis of pyridine, the amino group on the modified polysiloxane undergoes a ring-opening reaction with the anhydride group on the modified polyolefin to form a cross-linked structure, and ultimately the hybrid polyolefin is prepared.

[0015] Further, in step A1, the dosage ratio of allyl methyl carbonate, epoxybutene, maleic anhydride, tetrahydrofuran, and azobisisobutyronitrile is 2 - 3 g : 6 - 8 g : 3 - 4 g : 45 - 50 mL : 0.3 - 0.5 g. The post-treatment includes: After the reaction kettle is cooled to room temperature, add the reaction solution into a rotary evaporator with a water bath temperature of 80 - 100 °C, and perform vacuum distillation until no liquid is collected to obtain the polyolefin.

[0016] Further, in step A2, the dosage ratio of polyolefin, N,N-dimethylformamide, triethylamine, and 2-hydroxy-4-benzyloxybenzophenone is 8 - 10 g : 40 - 50 mL : 0.3 - 0.5 g : 1 - 2 g. The post-treatment includes: After the reaction kettle is cooled to room temperature, add the reaction solution into a rotary evaporator with a water bath temperature of 80 - 100 °C, and perform vacuum distillation until no liquid is collected to obtain the modified polyolefin.

[0017] Further, in step A3, the dosage ratio of modified polyolefin, N,N-dimethylacetamide, pyridine, and modified polysiloxane is 10 - 12 g : 40 - 50 mL : 0.3 - 0.5 g : 5 - 6 g. The post-treatment includes: After the reaction kettle is cooled to room temperature, add the reaction solution into a rotary evaporator with a water bath temperature of 80 - 100 °C, and perform vacuum distillation until no liquid is collected to obtain the hybrid polyolefin.

[0018] Furthermore, the preparation method of the modified polysiloxane comprises the following steps: adding flame retardant particles, ethanol, sodium hydroxide powder, and deionized water into a reaction kettle, stirring at room temperature for 5 - 10 min, then raising the temperature of the reaction kettle to 60 - 80 °C, adding a silicon source solution into the reaction kettle, keeping warm and stirring for 60 - 80 min, and performing post-treatment to obtain the modified polysiloxane.

[0019] The reaction equation for preparing the modified polysiloxane is:

[0020]

[0021] The reaction principle for preparing the modified polysiloxane is: under the catalysis of an alkaline condition, the boric acid hydroxyl groups on the flame retardant particles react with the siloxane structures on 3-aminopropyltrimethoxysilane and perfluorohexylethyltrimethoxysilane to generate silanol groups through hydrolysis, and finally form a long-chain cross-linked structure, thereby obtaining the modified polysiloxane.

[0022] Furthermore, the dosage ratio of the flame retardant filler, ethanol, sodium hydroxide powder, deionized water, and the silicon source solution is 5 - 6 g: 20 - 24 mL: 0.5 - 0.8 g: 10 - 12 mL: 20 - 24 mL. The silicon source solution is obtained by mixing 3-aminopropyltrimethoxysilane, perfluorohexylethyltrimethoxysilane, and ethanol according to the dosage ratio of 2 - 3 g: 0.3 - 0.4 g: 10 - 12 mL. The post-treatment includes: after the reaction kettle is cooled to room temperature, adding the reaction solution into a rotary evaporator with a water bath temperature of 80 - 100 °C, and performing vacuum distillation until no liquid is collected, to obtain the modified polysiloxane.

[0023] Furthermore, the preparation method of the flame retardant particles comprises the following steps:

[0024] B1. Adding zinc acetate dihydrate, mercaptoethanol, thiourea, and N,N-dimethylformamide into a reaction kettle and stirring. After introducing nitrogen protection, raising the temperature of the reaction kettle to 150 - 160 °C, keeping warm and stirring for 8 - 10 h, and performing post-treatment to obtain modified zinc sulfide;

[0025] B2. Dispersing the modified zinc sulfide, triethylamine, and N,N-dimethylformamide into a reaction kettle and stirring. Adding the boronating solution into a constant pressure dropping funnel. Under continuous stirring, by controlling the dropping rate, ensuring that the boronating solution is uniformly added dropwise within 30 - 40 min. After the dropping is completed, raising the temperature of the reaction kettle to 60 - 80 °C, keeping warm and reacting for 6 - 8 h, and performing post-treatment to obtain the flame retardant particles.

[0026] The reaction equation for preparing the modified zinc sulfide is:

[0027]

[0028] The reaction principle for preparing modified zinc sulfide is as follows: Thiourea acts as a sulfur source and reacts with zinc acetate dihydrate to form zinc sulfide particles. And after the zinc sulfide particles are modified with thiol, an active structure is formed, thus preparing modified zinc sulfide. The hydroxyl groups on its surface undergo an elimination reaction with the chlorine groups on 4-chlorophenylboronic acid, and finally flame-retardant particles are prepared.

[0029] Further, in step B1, the dosage ratio of zinc acetate dihydrate, mercaptoethanol, thiourea, and N,N-dimethylformamide is 10 - 12 g : 3 - 5 g : 4 - 5 g : 60 - 80 mL. The post-treatment includes: after the reaction is completed, when the temperature of the reaction kettle drops to room temperature, add anhydrous ethanol with the same volume as the solvent to the reaction kettle. After standing for 1 - 2 h, filter the reaction solution to collect the filter cake. After washing the filter cake with methanol 3 - 5 times, transfer the filter cake to a drying oven at 60 °C and vacuum dry to constant weight to obtain modified zinc sulfide.

[0030] Further, in step B2, the dosage ratio of modified zinc sulfide, triethylamine, N,N-dimethylformamide, and swelling liquid is 4 - 6 g : 0.5 - 0.8 g : 20 - 25 mL : 10 - 12 mL. The boronating liquid is obtained by mixing 4-chlorophenylboronic acid and N,N-dimethylformamide according to the dosage ratio of 2 - 3 g : 10 - 12 mL. The post-treatment includes: after the reaction is completed, when the temperature of the reaction kettle drops to room temperature, add anhydrous ethanol with the same volume as the solvent to the reaction kettle. After standing for 1 - 2 h, filter the reaction solution to collect the filter cake. After washing the filter cake with methanol 3 - 5 times, transfer the filter cake to a drying oven at 60 °C and vacuum dry to constant weight to obtain flame-retardant particles.

[0031] The present invention also proposes a preparation method of a flame-retardant insulating cover applied to the safety protection of fuses: Add hybrid polyolefin, flame-retardant particles, plasticizer, antioxidant, heat stabilizer, and lubricant into a twin-screw extruder, melt and extrude into a molding die, and naturally cool and solidify to obtain a fuse cover.

[0032] Further, the temperatures of the 6 temperature zones of the twin-screw extruder from the feeding end to the discharging end are 200 °C, 215 °C, 215 °C, 220 °C, 220 °C, and 230 °C in sequence. The main shaft rotation speed of the twin-screw extruder is 40 - 60 rpm, and the pressure is 100 - 150 bar.

[0033] The present invention has the following beneficial effects:

[0034] 1. First, the present invention prepares zinc sulfide particles with a surface-modified organic layer as a flame retardant filler. The organic modification layer on the surface enhances the compatibility between the zinc sulfide particles and the organic material, enabling the flame retardant filler to be evenly dispersed inside the shield. During the combustion process, the zinc sulfide decomposes into a zinc oxide flame retardant layer, and the boron-modified structure on its surface forms boron oxides. The two cooperate synergistically to isolate heat propagation and flame spread. Additionally, sulfur dioxide gas is generated through the decomposition of zinc sulfide, and flame retardant gases are produced by the pyrolysis of the boron-containing structure, thereby reducing the oxygen concentration and further enhancing the flame retardant performance of the shield. Moreover, the excellent optical properties of zinc sulfide compensate for the microscopic defects in the organic system, reducing light scattering inside and thus increasing the light transmittance, facilitating the staff to observe the fuse condition and reducing accidents.

[0035] 2. The present invention uses flame retardant particles as a carrier to form a modified polysiloxane with a three-dimensional chain segment structure through the hydrolysis of siloxane. The silicon-oxygen structure in the polysiloxane provides high temperature stability and low polarizability, improving the electrical breakdown resistance. The perfluoro group reduces the dielectric constant, decreases the dielectric loss, and enhances the arc resistance. The combination of the two further inhibits charge transfer, endowing the material with an extremely low conductivity and an extremely high volume resistivity, thereby significantly improving the insulation performance of the material. During the combustion process, the polysiloxane can enhance the flame retardant performance of the material through its chemical stability, thermal stability, and the ability to form a protective carbon layer at high temperatures. The perfluoro group reduces the flammability of the material and slows down the fire spread rate through its low surface energy, chemical inertness, and low thermal conductivity characteristics. The two improve the flame retardant performance of the material through synergistic effects.

[0036] 3. The present invention also uses a modified polysiloxane chain segment as a chain extender to hybridize a modified polyolefin structure with a light stabilizer structure inside the chain segment, thereby preparing a hybrid polyolefin. The silicon-oxygen structure in the hybrid polyolefin provides high bond energy and low ultraviolet absorption, ensuring that the material is not easily directly degraded under ultraviolet light irradiation. The perfluoro group enhances the hydrophobicity and antioxidant property of the material, further reducing the photooxidation process induced by ultraviolet light and improving the weather resistance of the material. The light stabilizer effectively prevents long-term damage to the material by ultraviolet light by absorbing ultraviolet light and capturing free radicals. The synergistic effect of these three enables the polysiloxane to not only greatly improve its anti-ultraviolet performance but also stably work for a long time under harsh environments such as high temperature, high humidity, and ultraviolet irradiation, thus ensuring the service life of the fuse shield. Detailed Embodiments

[0037] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0038] Example 1

[0039] This example is used to provide a preparation method of flame retardant particles for the preparation of flame retardant and insulating shields applied to fuse safety protection, including the following steps:

[0040] Step ①: Prepare modified zinc oxide

[0041] Weigh: 1000.0 g of zinc acetate dihydrate, 300.0 g of mercaptoethanol, 400.0 g of thiourea and 6000.0 mL of N,N-dimethylformamide and add them to the reaction kettle for stirring. After introducing nitrogen protection, the temperature of the reaction kettle is raised to 150 °C, and it is kept stirring for 8 h. After the reaction is completed, when the temperature of the reaction kettle is lowered to room temperature, add anhydrous ethanol with the same volume as the solvent to the reaction kettle. After standing for 1 h, filter the reaction solution to collect the filter cake. After washing the filter cake 3 times with methanol, transfer the filter cake to a drying oven at 60 °C and vacuum dry it to constant weight to obtain modified zinc sulfide.

[0042] Step ②: Prepare flame retardant particles

[0043] Weigh: 200.0 g of 4-chlorophenylboronic acid and 1000.0 mL of N,N-dimethylformamide and mix them to obtain a boronated solution;

[0044] Weigh: 400.0 g of modified zinc sulfide, 50.0 g of triethylamine and 2000.0 mL of N,N-dimethylformamide and disperse them in the reaction kettle for stirring. Add 1000.0 mL of the boronated solution to the constant pressure dropping funnel. Under continuous stirring, by controlling the dropping rate, ensure that the boronated solution is evenly dropped within 30 min. After the dropping is completed, raise the temperature of the reaction kettle to 60 °C and keep reacting for 6 h. After the reaction is completed, when the temperature of the reaction kettle is lowered to room temperature, add anhydrous ethanol with the same volume as the solvent to the reaction kettle. After standing for 1 h, filter the reaction solution to collect the filter cake. After washing the filter cake 3 times with methanol, transfer the filter cake to a drying oven at 60 °C and vacuum dry it to constant weight to obtain flame retardant particles.

[0045] Example 2

[0046] This example is used to provide a preparation method of flame retardant particles for the preparation of flame retardant and insulating shields applied to fuse safety protection, including the following steps:

[0047] Step ①: Prepare modified zinc oxide

[0048] Weigh: 1200.0 g of zinc acetate dihydrate, 500.0 g of mercaptoethanol, 500.0 g of thiourea and 8000.0 mL of N,N-dimethylformamide are added to a reaction kettle and stirred. After introducing nitrogen for protection, the temperature of the reaction kettle is raised to 160 °C, and it is kept stirring for 10 h. After the reaction is completed, when the temperature of the reaction kettle drops to room temperature, anhydrous ethanol with the same volume as the solvent is added to the reaction kettle. After standing for 2 h, the reaction solution is filtered by suction to collect the filter cake. After washing the filter cake 5 times with methanol, the filter cake is transferred to a drying oven at 60 °C and vacuum dried to a constant weight to obtain modified zinc sulfide.

[0049] Step ②, preparing flame-retardant particles

[0050] Weigh: 300.0 g of 4-chlorophenylboronic acid and 1200.0 mL of N,N-dimethylformamide are mixed to obtain a boration solution;

[0051] Weigh: 600.0 g of modified zinc sulfide, 80.0 g of triethylamine and 2500.0 mL of N,N-dimethylformamide are dispersed into a reaction kettle and stirred. 1200.0 mL of the boration solution is added to a constant-pressure dropping funnel. Under continuous stirring, by controlling the dropping rate, ensure that the boration solution is uniformly dropped within 40 min. After the dropping is completed, the temperature of the reaction kettle is raised to 80 °C, and it is kept reacting for 8 h. After the reaction is completed, when the temperature of the reaction kettle drops to room temperature, anhydrous ethanol with the same volume as the solvent is added to the reaction kettle. After standing for 2 h, the reaction solution is filtered by suction to collect the filter cake. After washing the filter cake 5 times with methanol, the filter cake is transferred to a drying oven at 60 °C and vacuum dried to a constant weight to obtain flame-retardant particles.

[0052] Example 3

[0053] This example is used to provide a preparation method of flame-retardant particles for a flame-retardant insulating cover used for the safety protection of a fuse, including the following steps:

[0054] Step ①, preparing modified zinc oxide

[0055] Weigh: 1100.0 g of zinc acetate dihydrate, 400.0 g of mercaptoethanol, 450.0 g of thiourea and 7200.0 mL of N,N-dimethylformamide are added to a reaction kettle and stirred. After introducing nitrogen for protection, the temperature of the reaction kettle is raised to 154 °C, and it is kept stirring for 9 h. After the reaction is completed, when the temperature of the reaction kettle drops to room temperature, anhydrous ethanol with the same volume as the solvent is added to the reaction kettle. After standing for 2 h, the reaction solution is filtered by suction to collect the filter cake. After washing the filter cake 4 times with methanol, the filter cake is transferred to a drying oven at 60 °C and vacuum dried to a constant weight to obtain modified zinc sulfide.

[0056] Step ②, preparing flame-retardant particles

[0057] Weigh: 250.0 g of 4-chlorophenylboronic acid and 1100.0 mL of N,N-dimethylformamide are mixed to obtain a borating solution;

[0058] Weigh: 500.0 g of modified zinc sulfide, 72.0 g of triethylamine and 2400.0 mL of N,N-dimethylformamide are dispersed into a reaction kettle and stirred. 1100.0 mL of the borating solution is added to a constant pressure dropping funnel. Under continuous stirring, by controlling the dropping rate, ensure that the borating solution is evenly dropped within 36 min. After the dropping is completed, the temperature of the reaction kettle rises to 72 °C, and keep the temperature for reaction for 7 h. After the reaction is completed, wait for the temperature of the reaction kettle to drop to room temperature, add anhydrous ethanol with the same volume as the solvent to the reaction kettle. After standing for 2 h, filter the reaction solution to collect the filter cake. After washing the filter cake 4 times with methanol, transfer the filter cake to an oven at 60 °C and vacuum dry to constant weight to obtain flame retardant particles.

[0059] Example 4

[0060] This example is used to provide a preparation method of modified polysiloxane for preparing a flame retardant insulating cover for fuse safety protection, including the following steps:

[0061] Weigh: 200.0 g of 3-aminopropyltrimethoxysilane, 30.0 g of perfluorohexylethyltrimethoxysilane and 1000.0 mL of ethanol are mixed to obtain a silicon source solution;

[0062] Weigh: 500.0 g of the flame retardant particles prepared in Example 1, 2000.0 mL of ethanol, 50.0 g of sodium hydroxide powder and 1000.0 mL of deionized water are added to a reaction kettle. After stirring at room temperature for 5 min, the temperature of the reaction kettle rises to 60 °C, and 2000.0 mL of the silicon source solution is added to the reaction kettle. Keep stirring at a constant temperature for 60 min. After the reaction kettle cools to room temperature, add the reaction solution into a rotary evaporator with a water bath temperature of 80 °C and distill under reduced pressure until no liquid is collected to obtain modified polysiloxane.

[0063] Example 5

[0064] This example is used to provide a preparation method of modified polysiloxane for preparing a flame retardant insulating cover for fuse safety protection, including the following steps:

[0065] Weigh: 300.0 g of 3-aminopropyltrimethoxysilane, 40.0 g of perfluorohexylethyltrimethoxysilane and 1200.0 mL of ethanol are mixed to obtain a silicon source solution;

[0066] Weigh: 600.0 g of the flame retardant particles prepared in Example 2, 2400.0 mL of ethanol, 80.0 g of sodium hydroxide powder, and 1200.0 mL of deionized water were added to the reaction kettle. After stirring at room temperature for 10 min, the temperature of the reaction kettle was raised to 80 °C, and 2400.0 mL of the silicon source solution was added to the reaction kettle. After heat preservation and stirring for 80 min, after the reaction kettle was cooled to room temperature, the reaction solution was added to a rotary evaporator with a water bath temperature of 100 °C, and vacuum distillation was carried out until no liquid was collected, obtaining the modified polysiloxane.

[0067] Example 6

[0068] This example is used to provide a preparation method of modified polysiloxane for preparing a flame retardant and insulating cover for fuse safety protection, including the following steps:

[0069] Weigh: 240.0 g of 3-aminopropyltrimethoxysilane, 36.0 g of perfluorohexylethyltrimethoxysilane, and 1100.0 mL of ethanol were mixed to obtain the silicon source solution;

[0070] Weigh: 540.0 g of the flame retardant particles prepared in Example 3, 2100.0 mL of ethanol, 72.0 g of sodium hydroxide powder, and 1100.0 mL of deionized water were added to the reaction kettle. After stirring at room temperature for 8 min, the temperature of the reaction kettle was raised to 72 °C, and 2100.0 mL of the silicon source solution was added to the reaction kettle. After heat preservation and stirring for 72 min, after the reaction kettle was cooled to room temperature, the reaction solution was added to a rotary evaporator with a water bath temperature of 90 °C, and vacuum distillation was carried out until no liquid was collected, obtaining the modified polysiloxane.

[0071] Example 7

[0072] This example is used to provide a preparation method of hybrid polyolefin for preparing a flame retardant and insulating cover for fuse safety protection, including the following steps:

[0073] Step I. Prepare polyolefin

[0074] Weigh: 200.0 g of allyl methyl carbonate, 600.0 g of epoxy butene, 300.0 g of maleic anhydride, and 4500.0 mL of tetrahydrofuran were added to the reaction kettle. After the temperature of the reaction kettle was raised to 40 °C, 30.0 g of azobisisobutyronitrile was added to the reaction kettle. After heat preservation and stirring for 2 h, after the reaction kettle was cooled to room temperature, the reaction solution was added to a rotary evaporator with a water bath temperature of 80 °C, and vacuum distillation was carried out until no liquid was collected, obtaining the polyolefin.

[0075] Step II. Prepare modified polyolefin

[0076] Weigh: 800.0 g of polyolefin and 4000.0 mL of N,N-dimethylformamide are added to a reaction kettle. The temperature of the reaction kettle is raised to 40 °C. After maintaining the temperature and stirring for 10 min, 30.0 g of triethylamine and 100.0 g of 2-hydroxy-4-benzyloxybenzophenone are added to the reaction kettle. After maintaining the reaction at the same temperature for 30 min, after the reaction kettle is cooled to room temperature, the reaction solution is added to a rotary evaporator with a water bath temperature of 80 °C, and distilled under reduced pressure until no more liquid is collected, to obtain modified polyolefin.

[0077] Step III: Prepare hybrid polyolefin

[0078] Weigh: 1000.0 g of modified polyolefin and 4000.0 mL of N,N-dimethylacetamide are added to a reaction kettle. The temperature of the reaction kettle is raised to 40 °C. After maintaining the temperature and stirring for 10 min, 30.0 g of pyridine and 500.0 g of the modified polysiloxane prepared in Example 4 are added to the reaction kettle. Continue to maintain the temperature and stir at 40 °C. After the reaction kettle is cooled to room temperature, the reaction solution is added to a rotary evaporator with a water bath temperature of 80 °C, and distilled under reduced pressure until no more liquid is collected, to obtain hybrid polyolefin.

[0079] Example 8

[0080] This example is used to provide a preparation method of hybrid polyolefin for preparing a flame-retardant insulating cover applied to the safety protection of fuses, including the following steps:

[0081] Step I: Prepare polyolefin

[0082] Weigh: 300.0 g of allyl methyl carbonate, 800.0 g of epoxybutene, 400.0 g of maleic anhydride and 5000.0 mL of tetrahydrofuran are added to a reaction kettle. After the temperature of the reaction kettle is raised to 60 °C, 50 g of azobisisobutyronitrile is added to the reaction kettle. Maintain the temperature and stir for 3 h. After the reaction kettle is cooled to room temperature, the reaction solution is added to a rotary evaporator with a water bath temperature of 100 °C, and distilled under reduced pressure until no more liquid is collected, to obtain polyolefin.

[0083] Step II: Prepare modified polyolefin

[0084] Weigh: 1000.0 g of polyolefin and 5000.0 mL of N,N-dimethylformamide are added to a reaction kettle. The temperature of the reaction kettle is raised to 60 °C. After maintaining the temperature and stirring for 15 min, 50.0 g of triethylamine and 200.0 g of 2-hydroxy-4-benzyloxybenzophenone are added to the reaction kettle. Maintain the reaction for 40 min. After the reaction kettle is cooled to room temperature, the reaction solution is added to a rotary evaporator with a water bath temperature of 100 °C, and distilled under reduced pressure until no more liquid is collected, to obtain modified polyolefin.

[0085] Step III: Prepare hybrid polyolefin

[0086] Weigh: 1200.0 g of modified polyolefin and 5000.0 mL of N,N-dimethylacetamide are added to a reaction kettle. The temperature of the reaction kettle is raised to 50 °C. After maintaining the temperature and stirring for 15 min, 50.0 g of pyridine and 600.0 g of the modified polysiloxane prepared in Example 5 are added to the reaction kettle. Continue to maintain the temperature and stir at 60 °C. After the reaction kettle is cooled to room temperature, the reaction solution is added to a rotary evaporator with a water bath temperature of 100 °C, and vacuum distillation is carried out until no liquid is collected, obtaining hybrid polyolefin.

[0087] Example 9

[0088] This example is used to provide a preparation method of hybrid polyolefin for preparing a flame-retardant insulating cover for fuse safety protection, including the following steps:

[0089] Step Ⅰ. Prepare polyolefin

[0090] Weigh: 250.0 g of allyl methyl carbonate, 700.0 g of epoxybutene, 350.0 g of maleic anhydride and 4800.0 mL of tetrahydrofuran are added to a reaction kettle. After the temperature of the reaction kettle is raised to 50 °C, 40.0 g of azobisisobutyronitrile is added to the reaction kettle. Maintain the temperature and stir for 3 h. After the reaction kettle is cooled to room temperature, the reaction solution is added to a rotary evaporator with a water bath temperature of 90 °C, and vacuum distillation is carried out until no liquid is collected, obtaining polyolefin.

[0091] Step Ⅱ. Prepare modified polyolefin

[0092] Weigh: 900.0 g of polyolefin and 4500.0 mL of N,N-dimethylformamide are added to a reaction kettle. The temperature of the reaction kettle is raised to 50 °C. After maintaining the temperature and stirring for 12 min, 40.0 g of triethylamine and 150.0 g of 2-hydroxy-4-benzyloxybenzophenone are added to the reaction kettle. Carry out a heat preservation reaction for 36 min. After the reaction kettle is cooled to room temperature, the reaction solution is added to a rotary evaporator with a water bath temperature of 90 °C, and vacuum distillation is carried out until no liquid is collected, obtaining modified polyolefin.

[0093] Step Ⅲ. Prepare hybrid polyolefin

[0094] Weigh: 1100.0 g of modified polyolefin and 4800.0 mL of N,N-dimethylacetamide are added to a reaction kettle. The temperature of the reaction kettle is raised to 45 °C. After maintaining the temperature and stirring for 12 min, 40.0 g of pyridine and 540.0 g of the modified polysiloxane prepared in Example 6 are added to the reaction kettle. Continue to maintain the temperature and stir at 50 °C. After the reaction kettle is cooled to room temperature, the reaction solution is added to a rotary evaporator with a water bath temperature of 90 °C, and vacuum distillation is carried out until no liquid is collected, obtaining hybrid polyolefin.

[0095] Example 10

[0096] This embodiment is used to provide a preparation method of a flame-retardant insulating cover for fuse safety protection, including the following steps:

[0097] Weigh: 8000.0 g of the hybrid polyolefin prepared in Example 7, 2000.0 g of the flame-retardant particles prepared in Example 1, 300.0 g of dibutyl phthalate, 1 - 2 g of tris(2,4-di-tert-butylphenyl) phosphate, 200.0 g of lead stearate, and 200.0 g of polyethylene wax are added to a twin-screw extruder. The temperatures of the 6 temperature zones of the twin-screw extruder from the feed end to the discharge end are 200 °C, 215 °C, 215 °C, 220 °C, 220 °C, and 230 °C in sequence. The main shaft speed of the twin-screw extruder is 40 rpm, the pressure is 100 bar, and it is melt-extruded into a molding die and naturally cooled and shaped to obtain a fuse cover.

[0098] Example 11

[0099] This embodiment is used to provide a preparation method of a flame-retardant insulating cover for fuse safety protection, including the following steps:

[0100] Weigh: 10000.0 g of the hybrid polyolefin prepared in Example 8, 3000.0 g of the flame-retardant particles prepared in Example 2, 500.0 g of dibutyl phthalate, 200.0 g of tris(2,4-di-tert-butylphenyl) phosphate, 300.0 g of lead stearate, and 300.0 g of polyethylene wax are added to a twin-screw extruder. The temperatures of the 6 temperature zones of the twin-screw extruder from the feed end to the discharge end are 200 °C, 215 °C, 215 °C, 220 °C, 220 °C, and 230 °C in sequence. The main shaft speed of the twin-screw extruder is 60 rpm, the pressure is 150 bar, and it is melt-extruded into a molding die and naturally cooled and shaped to obtain a fuse cover.

[0101] Example 12

[0102] This embodiment is used to provide a preparation method of a flame-retardant insulating cover for fuse safety protection, including the following steps:

[0103] Weigh: 9000.0 g of the hybrid polyolefin prepared in Example 9, 2500.0 g of the flame-retardant particles prepared in Example 3, 400.0 g of dibutyl phthalate, 150.0 g of tris(2,4-di-tert-butylphenyl) phosphate, 250.0 g of lead stearate, and 250.0 g of polyethylene wax are added to a twin-screw extruder. The temperatures of the 6 temperature zones of the twin-screw extruder from the feed end to the discharge end are 200 °C, 215 °C, 215 °C, 220 °C, 220 °C, and 230 °C in sequence. The main shaft speed of the twin-screw extruder is 50 rpm, the pressure is 120 bar, and it is melt-extruded into a molding die and naturally cooled and shaped to obtain a fuse cover.

[0104] Comparative Example 1

[0105] The difference between this example and Comparative Example 12 is that during the preparation of the hybrid polyolefin used, the flame retardant particles were not used during the preparation of the modified polysiloxane.

[0106] Comparative Example 2

[0107] The difference between this example and Comparative Example 12 is that the use of modified polysiloxane was cancelled during the preparation of the hybrid polyolefin used.

[0108] Comparative Example 3

[0109] The difference between this example and Comparative Example 12 is that during the preparation of the hybrid polyolefin used, Step II was cancelled. In Step III, polyolefin was used to replace the modified polyolefin in equal amount, and during the preparation of the modified polysiloxane used, the use of perfluorohexylethyltrimethoxysilane was cancelled.

[0110] Performance Test:

[0111] Referring to the standard GB / T 2408-2021 "Plastics - Determination of burning behaviour - Horizontal and vertical methods", the vertical burning grade of the fuse covers prepared in Examples 10 - 12 and Comparative Examples 1 - 3 was tested;

[0112] Referring to the standard GB / T 31838.2-2019 "Solid insulating materials - Dielectric and resistive properties - Part 2: Resistive properties (DC method) - Volume resistance and volume resistivity", the volume resistivity of the fuse covers prepared in Examples 10 - 12 and Comparative Examples 1 - 3 was tested;

[0113] Referring to the standard GB / T 2410-2008 "Determination of transmittance and haze of transparent plastics", the transmittance of the fuse covers prepared in Examples 10 - 12 and Comparative Examples 1 - 3 was tested;

[0114] Referring to the standard GB / T 9867-2008 "Rubber, vulcanized or thermoplastic - Determination of abrasion resistance (rotary roller abrader method)", the volume abrasion of the fuse covers prepared in Examples 10 - 12 and Comparative Examples 1 - 3 was tested;

[0115] Referring to the standard GB / T 17657-2022 "Test methods for physical and chemical properties of wood-based panels and wood-based panels with surface decoration", the scratch resistance grade of the fuse covers prepared in Examples 10 - 12 and Comparative Examples 1 - 3 was tested. The specific data are shown in Table 1;

[0116] The ultraviolet aging test will be carried out on the fuse covers prepared in Example 12 and Comparative Examples 1-3 with reference to the standard GB / T 16422.3-2022 "Plastics - Methods of exposure to laboratory light sources - Part 3: Fluorescent ultraviolet lamps". The light transmittance retention rate of the fuse covers will be measured with reference to the standard GB / T 2410-2008, the volume abrasion of the fuse covers will be measured with reference to the standard GB / T 9867-2008, and the scratch resistance grade of the fuse covers will be measured with reference to the standard GB / T 17657-2022. The specific data are shown in Table 2.

[0117] Table 1 - Performance test data table of each sample

[0118]

[0119] Table 2 - Performance test data table of each sample after ultraviolet aging

[0120]

[0121] Data analysis:

[0122] By comparing and analyzing the data in Table 1 above, the vertical burning grade of the fuse cover prepared in the present invention is V-0, the volume resistivity is 3.72×10 16 Ω·m, the light transmittance is 97.6%, the volume abrasion is 27.9mm 3 and the scratch resistance grade is 5. All the data are better than those of the comparative examples. By comparing and analyzing the data in Table 1 above, after ultraviolet aging, the light transmittance of the fuse cover prepared in the present invention is 96.4%, the volume abrasion is 28.4mm 3 and the scratch resistance grade is 5. All the data are also better than those of the comparative examples;

[0123] It shows that in the present invention, zinc sulfide particles with a surface-modified organic layer are first prepared as a flame retardant filler. The organic modification layer on the surface enhances the compatibility between the zinc sulfide particles and the organic material, so that the flame retardant filler is evenly dispersed inside the cover, thus significantly enhancing the wear resistance of the material. During the combustion process, zinc sulfide decomposes into a zinc oxide flame retardant layer, and the boron-modified structure on its surface forms boron oxides. The two cooperate synergistically to isolate the heat transfer and flame spread. And sulfur dioxide gas is generated by the decomposition of zinc sulfide and flame retardant gas is generated by the pyrolysis of the boron-containing structure, thereby reducing the oxygen concentration and further improving the flame retardant performance of the cover. Moreover, the excellent optical properties of zinc sulfide make up for the microscopic defects in the organic system, reduce the internal light scattering, thereby improving the light transmittance, facilitating the staff to observe the fuse situation and reducing accidents;

[0124] It is noted that in the present invention, by using flame-retardant particles as carriers, a modified polysiloxane with a three-dimensional chain segment structure is formed through the hydrolysis of siloxane. The silicon-oxygen structure in the polysiloxane provides high-temperature stability, low polarizability, and improves the electrical breakdown resistance. The perfluoro group reduces the dielectric constant, decreases the dielectric loss, and improves the arc resistance. The combination of the two further inhibits charge transport, enabling the material to have an extremely low conductivity and an extremely high volume resistivity, thus significantly enhancing the insulation performance of the material. Moreover, during the combustion process, the polysiloxane can improve the flame retardancy of the material through its chemical stability, thermal stability, and the ability to form a protective carbon layer at high temperatures. The perfluoro group reduces the flammability of the material and slows down the spread of fire through its low surface energy, chemical inertness, and low thermal conductivity characteristics. The two further improve the flame retardancy of the material through their synergistic effect;

[0125] It is noted that in the present invention, a modified polyolefin structure with a light stabilizer structure modified within the chain segment is hybridized with a modified polysiloxane chain segment as a chain extender to prepare a hybrid polyolefin. The silicon-oxygen structure in the hybrid polyolefin provides high bond energy and low ultraviolet absorption, ensuring that the material is not easily directly degraded under ultraviolet light irradiation. The perfluoro group enhances the hydrophobicity and antioxidant property of the material, further reducing the photooxidation process induced by ultraviolet light and improving the weather resistance of the material. The light stabilizer effectively prevents the long-term damage of ultraviolet light to the material by absorbing ultraviolet light, capturing free radicals, etc. The synergistic effect of these three enables the polysiloxane to not only be greatly improved in anti-ultraviolet performance but also work stably for a long time under harsh environments such as high temperature, high humidity, and ultraviolet irradiation, thus ensuring the service life of the fuse cover.

[0126] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the present invention to the specific implementation manners. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A flame retardant insulating shield for fuse safety protection, characterized in that: The invention comprises the following raw materials in parts by weight: 80-100 parts of hybrid polyolefin, 20-30 parts of flame retardant particles, 3-5 parts of plasticizer, 1-2 parts of antioxidant, 2-3 parts of heat stabilizer and 2-3 parts of lubricant.

2. The flame retardant insulating shield for fuse safety protection according to claim 1, characterized in that: The preparation method of the hybrid polyolefin comprises the following steps: A1. Add allyl methyl carbonate, epoxybutene, maleic anhydride and tetrahydrofuran into a reactor. After the temperature of the reactor is raised to 40-60° C., add azobisisobutyronitrile into the reactor, keep the temperature and stir for 2-3 hours, and perform post-treatment to obtain polyolefin. A2, adding polyolefin and N,N-dimethylformamide into a reactor, raising the temperature of the reactor to 40-60°C, stirring for 10-15 minutes, adding triethylamine and 2-hydroxy-4-benzyloxybenzophenone into the reactor, keeping the temperature for 30-40 minutes, and post-treating to obtain modified polyolefin; A3. Add modified polyolefin and N,N-dimethylacetamide into a reactor, raise the temperature of the reactor to 40-50°C, keep warm and stir for 10-15 minutes, add pyridine and modified polysiloxane into the reactor, continue to keep warm and stir at 40-60°C, and post-treat to obtain hybrid polyolefin.

3. The flame retardant insulating shield for fuse safety protection according to claim 2, characterized in that: In step A1, the amount ratio of allyl methyl carbonate, epoxybutene, maleic anhydride, tetrahydrofuran and azobisisobutyronitrile is 2-3g:6-8g:3-4g:45-50mL:0.3-0.5g; in step A2, the amount ratio of polyolefin, N,N-dimethylformamide, triethylamine and 2-hydroxy-4-benzyloxybenzophenone is 8-10g:40-50mL:0.3-0.5g:1-2g; in step A3, the amount ratio of modified polyolefin, N,N-dimethylacetamide, pyridine and modified polysiloxane is 10-12g:40-50mL:0.3-0.5g:5-6g.

4. The flame retardant insulating shield for fuse safety protection according to claim 2, characterized in that: The preparation method of the modified polysiloxane comprises the following steps: adding flame retardant particles, ethanol, sodium hydroxide powder and deionized water into a reactor, stirring for 5-10 minutes at room temperature, raising the temperature of the reactor to 60-80° C., adding silicon source liquid into the reactor, keeping the temperature and stirring for 60-80 minutes, and post-treating to obtain the modified polysiloxane.

5. The flame retardant insulating shield for fuse safety protection according to claim 4, characterized in that: The dosage ratio of flame retardant filler, ethanol, sodium hydroxide powder, deionized water and silicon source liquid is 5-6g:20-24mL:0.5-0.8g:10-12mL:20-24mL, and the silicon source liquid is obtained by mixing 3-aminopropyltrimethoxysilane, perfluorohexylethyltrimethoxysilane and ethanol in the dosage ratio of 2-3g:0.3-0.4g:10-12mL.

6. The flame retardant insulating shield for fuse safety protection according to claim 1, characterized in that: The method for preparing the flame retardant particles comprises the following steps: B1. Add zinc acetate dihydrate, mercaptoethanol, thiourea and N,N-dimethylformamide into a reaction kettle and stir. After nitrogen protection, the temperature of the reaction kettle is increased to 150-160° C., and the mixture is stirred for 8-10 hours. After post-treatment, modified zinc sulfide is obtained. B2. Disperse modified zinc sulfide, triethylamine and N,N-dimethylformamide in a reactor and stir. Add the boronized liquid into a constant pressure dropping funnel. Under continuous stirring, control the dropping rate to ensure that the boronized liquid is evenly added within 30-40 minutes. After the addition is completed, the temperature of the reactor is raised to 60-80°C, and the reaction is kept warm for 6-8 hours. The flame-retardant particles are obtained by post-treatment.

7. The flame retardant insulating shield for fuse safety protection according to claim 6, characterized in that: In step B1, the dosage ratio of zinc acetate dihydrate, mercaptoethanol, thiourea and N,N-dimethylformamide is 10-12g:3-5g:4-5g:60-80mL; in step B2, the dosage ratio of modified zinc sulfide, triethylamine, N,N-dimethylformamide and swelling liquid is 4-6g:0.5-0.8g:20-25mL:10-12mL, and the boronized liquid is obtained by mixing 4-chlorophenylboric acid and N,N-dimethylformamide in a dosage ratio of 2-3g:10-12mL.

8. A method for preparing a flame-retardant insulating shield for fuse safety protection according to any one of claims 1 to 7, characterized in that: The hybrid polyolefin, flame retardant particles, plasticizer, antioxidant, heat stabilizer and lubricant are added into a twin-screw extruder, melt-extruded into a molding die, and naturally cooled and shaped to obtain a fuse shield.

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