Low-smoke halogen-free aging-resistant insulated cable and preparation method thereof

Abstract

The invention discloses a low-smoke halogen-free aging-resistant insulated cable and a preparation method thereof, belongs to the technical field of cable preparation, and is used for solving the technical problem that the smoke suppression performance and the aging resistance of a sheath layer of an insulated cable in the prior art need to be further improved. The preparation method specifically comprises the following steps: mixing polypropylene, SBS-g-MAH, modified nanoparticles, a flame-retardant modified monomer, an initiator and an auxiliary additive, adding the mixture into a double-screw extruder, melting the mixture, extruding the melt mixture and coating the melt outside a wrapping layer to form a sheath layer, thereby obtaining the insulated cable. The modified POSS and the phenolic resin are mixed to prepare the modified microspheres, and the nickel acetate solution is further introduced for complexing deposition to obtain the modified nanoparticles, so that not only are the smoke suppression performance and the flame retardant performance of the insulated cable sheath layer improved, but also the mechanical performance and the thermal aging resistance of the cable sheath layer are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cable preparation, in particular to a low-smoke halogen-free aging-resistant insulated cable and a preparation method thereof. BACKGROUND

[0002] With the rapid development of urban infrastructure, power systems and rail transit, insulated cables are increasingly widely used in high-safety and high-stability environments, and smoke suppression performance, flame retardant performance and aging resistance have gradually become important indicators for evaluating the technical performance.

[0003] Traditional polyvinyl chloride (PVC) sheaths have good flame retardant performance, but release a large amount of smoke and toxic halogenated gases during combustion, which is difficult to meet modern environmental and safety requirements. Therefore, low-smoke halogen-free materials gradually replace PVC as the mainstream choice. The current commonly used insulation materials include polyethylene (PE), polypropylene (PP), ethylene-vinyl acetate copolymer (EVA) and their blended modification systems. In order to improve the flame retardant and aging resistance performance, researchers generally use physical blending methods such as adding inorganic flame retardants, phosphorus-nitrogen flame retardants, antioxidants and light stabilizers to enhance the flame retardant efficiency, thermal stability and environmental adaptability of the materials.

[0004] In the prior art, although the above-mentioned materials and modification methods improve the flame retardant and aging resistance performance of the insulated cable to some extent, there are still many shortcomings in practical application:

[0005] Firstly, the use of traditional inorganic flame retardants in large quantities easily leads to a decrease in the mechanical properties and poor processing performance of the materials. Secondly, some phosphorus-nitrogen flame retardants are easily volatile or decomposed during processing, the flame retardant effect is unstable, and there is a risk of migration after long-term service, which affects the stability of the insulation.

[0006] At the same time, the commonly used anti-aging additives are mostly in the form of physical doping, lack of chemical bonding with the polymer matrix, and are easily affected by external factors such as temperature and humidity, leading to material embrittlement and cracking during thermal oxidative aging. In addition, the poor interfacial compatibility between the flame retardant components and the polymer limits the dispersion effect and synergistic performance, and it is difficult to build a stable flame retardant and anti-aging network structure. SUMMARY

[0007] The present application relates to the technical field of cable preparation, in particular to a low-smoke halogen-free aging-resistant insulated cable and a preparation method thereof.

[0008] The technical problems to be solved by the present application are to provide a low-smoke halogen-free aging-resistant insulated cable and a preparation method thereof, which can further improve the smoke suppression performance and aging resistance of the sheath layer of the insulated cable in the prior art.

[0009] S1. Arrange several cable cores in parallel and fill the gaps between the cable cores with filler to form a filler layer. Use wrapping tape to wrap the several cable cores filled with the filler layer together to form a wrapping layer on the outside of the several cable cores.

[0010] S2. 1,2-Epoxy-5-hexene, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-ethanol 10-oxide, aluminum chloride and tetrahydrofuran are placed in a reaction vessel and stirred. The reaction vessel is heated to 50-60℃ and kept at the temperature for 4-6 hours. The flame-retardant modified monomer is obtained after post-treatment.

[0011] The reaction formula for preparing flame-retardant modified monomers is as follows:

[0012]

[0013] The reaction principle for preparing flame-retardant modified monomers is as follows:

[0014] During the reaction, under the catalysis of aluminum chloride, 1,2-epoxy-5-hexene and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-ethanol 10-oxide undergo a ring-opening reaction to obtain an olefin-modified flame-retardant monomer.

[0015] S3. Polypropylene, SBS-g-MAH, modified nanoparticles, flame-retardant modified monomers, initiators and auxiliary additives are mixed and added to a twin-screw extruder. After melting, the mixture is extruded and coated on the outside of the wrapping layer to form a sheath layer, thus obtaining an insulated cable.

[0016] Furthermore, in step S1, the filler is one or more of aluminum hydroxide, magnesium hydroxide, and calcium carbonate;

[0017] Further, in step S2, the ratio of 1,2-epoxy-5-hexene, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-ethanol 10-oxide, aluminum chloride, and tetrahydrofuran is 3-5 g: 4-6 g: 0.4-0.8 g: 130-150 mL. The post-treatment step includes: after the reaction is complete, wait for the reaction system to cool to room temperature, slowly add ice water until no more bubbles emerge, and add 2-5 wt% sodium hydroxide aqueous solution to pH. H is neutral. Ethyl acetate is added to the reaction solution for washing 2-4 times. The organic phase is transferred to a rotary evaporator at a temperature of 50-60℃ and evaporated until no liquid is collected to obtain the flame-retardant modified monomer. In step S3, the weight ratio of polypropylene, maleic anhydride modified polyethylene, modified nanoparticles, flame-retardant modified monomer, initiator and auxiliary additives is 60-80:4-6:4-7:8-10:0.5-1:1-3, and the initiator is dicumyl peroxide.

[0018] Furthermore, the auxiliary additive is composed of plasticizer, antioxidant and lubricant in a mass ratio of 4:2:4. The plasticizer is one or more of dibutyl phthalate, dioctyl sebacate and dibutyl sebacate. The antioxidant is one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite and 4,4'-thiobis(6-tert-butyl-3-methylphenol). The lubricant is one or more of fatty acid amide, zinc stearate and paraffin wax.

[0019] The twin-screw extruder has eight temperature zones from the feed inlet to the discharge outlet, with temperatures of 160℃, 160℃, 175℃, 175℃, 190℃, 190℃, 200℃, and 200℃ respectively. The main motor speed of the twin-screw extruder is 120-160 rpm, and the pressure is 80-120 bar.

[0020] Furthermore, the modified nanoparticles are prepared by: placing the modified microspheres and deionized water in a reaction vessel and stirring, adding sodium hydroxide aqueous solution to adjust the pH to 7±0.5, adding nickel acetate solution, stirring at room temperature for 10-12 hours, and then performing post-treatment to obtain the modified nanoparticles.

[0021] The preparation reaction principle of modified nanoparticles is as follows:

[0022] During the reaction, the modified microspheres, after being dispersed in water, come into full contact with the nickel acetate solution, and the sulfonic acid groups and phenolic hydroxyl groups react with Ni. 2+ Electrostatic adsorption or complexation occurs, effectively immobilizing metal ions. Simultaneously, adjusting the pH to neutral with sodium hydroxide facilitates the deprotonation of sulfonic acid groups, enhancing their affinity for Ni. 2+ This enhances the binding ability and effectively prevents the formation of nickel hydroxide precipitate, ensuring that nickel ions are uniformly bound to the surface or internal structure of the microspheres, thus obtaining modified nanoparticles.

[0023] Furthermore, the ratio of the modified microspheres, deionized water, and nickel acetate solution is 5-7g:100-120mL:40-60mL, the concentration of the sodium hydroxide aqueous solution is 2-5wt%, and the concentration of the nickel acetate solution is 20-30wt%. The post-treatment steps include: after the reaction is completed, let it stand for 10-12 hours, filter it, wash the filter cake with deionized water 2-4 times, transfer it to an oven at 70-80℃, and dry it to constant weight to obtain modified nanoparticles.

[0024] Furthermore, the modified microspheres are prepared by the following steps:

[0025] A1. Place the modified POSS and formaldehyde aqueous solution in a reaction vessel and stir at room temperature for 0.5-1h. Add phenol and sodium hydroxide aqueous solution, heat the reaction vessel to 75-85℃, and keep it at this temperature for 4-6h. After post-treatment, obtain intermediate I.

[0026] The reaction principle for the preparation of intermediate I is as follows:

[0027] During the reaction, under the alkaline conditions provided by sodium hydroxide, phenol reacts with formaldehyde to generate hydroxymethylphenol, which further forms a three-dimensional cross-linked phenolic network structure through methylene bridges. In this process, the modified POSS undergoes an aldehyde reaction with formaldehyde through its surface amino groups to generate a hydroxymethylamine structure, which then participates in the condensation of the phenolic network to achieve organic-inorganic covalent bonding, thus obtaining intermediate I.

[0028] A2. Place the formaldehyde aqueous solution in a reaction vessel and stir. Keep the reaction vessel in an ice bath at 0-5°C. Slowly add p-phenol sulfonic acid and stir at room temperature for 15-30 minutes to obtain intermediate II.

[0029] The reaction principle for the preparation of intermediate II is as follows:

[0030] During the reaction, under ice bath conditions, formaldehyde and p-phenol sulfonic acid undergo an aldehyde reaction to generate a sulfonic acid phenol intermediate containing hydroxymethyl groups. The low temperature environment helps to inhibit the degree of condensation and maintain the activity and controllability of the product in terms of molecular weight and structure, thus obtaining intermediate II with sulfonic acid groups and hydroxymethyl functional groups.

[0031] A3. Place intermediate I, deionized water and ethanol in a reaction vessel and stir. Add intermediate II, heat the reaction vessel to 65-75℃, and keep the reaction at this temperature for 2-4 hours. After post-treatment, the modified microspheres are obtained.

[0032] The reaction principle for the preparation of modified microspheres is as follows:

[0033] In the reaction process, intermediate I is first mixed with ethanol to form a resin solution, which is then emulsified and dispersed in an ethanol / water mixture to create a stable suspension emulsion environment. A pre-prepared p-phenol sulfonic acid prepolymer is then slowly added dropwise, causing it to undergo a co-condensation reaction with the phenolic hydroxyl and hydroxymethyl functional groups in the system, further crosslinking to form a three-dimensional network structure. Sulfonic acid groups are introduced into the interior and surface of the microspheres. As the system temperature rises to 75°C, the resin molecules continue to condense and crosslink inside the microdroplets, and the microdroplets gradually solidify into dense spherical particles, completing the emulsion spheroidization process and obtaining modified microspheres.

[0034] Further, in step A1, the ratio of modified POSS, formaldehyde aqueous solution, phenol, and sodium hydroxide aqueous solution is 0.5-1g:50-60mL:25-30g:8-10mL, the concentration of the formaldehyde aqueous solution is 37wt%, and the concentration of the sodium hydroxide aqueous solution is 2-5wt%. The post-processing step includes: after the reaction is complete, transferring the product to an oven with a vacuum degree of 0.09-0.11MPa, heating the oven to 70-80℃, and holding it at that temperature for 1-2 hours to obtain intermediate I; in step A2, the... The ratio of formaldehyde aqueous solution to p-phenol sulfonic acid is 5-10 mL: 10-15 g, and the concentration of the formaldehyde aqueous solution is 37 wt%. In step A3, the ratio of intermediate I, deionized water, ethanol and intermediate II is 5-10 g: 150-200 mL: 20-25 mL: 5-10 g. The post-processing steps include: after the reaction is completed, the reaction system is cooled to room temperature, filtered, the filter cake is washed 2-4 times with deionized water and ethanol, transferred to an oven at 60-70℃, and dried to constant weight to obtain modified microspheres.

[0035] Furthermore, the modified POSS is prepared by the following steps:

[0036] B1. Carboxylated carbon nanotubes, γ-aminopropyltriethoxysilane, tetrahydrofuran and N,N'-dicyclohexylcarbodiimide were placed in a reaction vessel and stirred. The mixture was reacted at room temperature for 2-4 hours. The modified POSS precursor was obtained after post-treatment.

[0037] The reaction principle for preparing the modified POSS precursor is as follows:

[0038] During the reaction, the carboxyl groups of the carboxylated carbon nanotubes are activated by N,N'-dicyclohexylcarbodiimide, and undergo an amidation reaction with the amino groups of γ-aminopropyltriethoxysilane, retaining the triethoxysilane end groups, ultimately yielding a silane coupling agent-modified POSS precursor.

[0039] B2. Place the modified POSS precursor, deionized water, and dimethyl sulfoxide in a reaction vessel and stir for 10-15 min. Add γ-mercaptopropyltriethoxysilane and γ-aminopropyltriethoxysilane. Heat the reaction vessel to 55-65℃ and maintain the temperature for 4-6 h. Cool the reaction vessel to room temperature, add ammonium fluoride, and stir at room temperature for 20-24 h. Post-treatment yields the modified POSS.

[0040] The preparation reaction principle of modified POSS is as follows:

[0041] During the reaction, under the hydrolysis of deionized water, the silicon-oxygen bonds of the modified POSS precursor, γ-mercaptopropyltriethoxysilane and γ-aminopropyltriethoxysilane are hydrolyzed into silanols. Multiple silanols undergo a condensation reaction under the catalysis of ammonium fluoride to form a cage-like modified POSS.

[0042] Further, in step B1, the ratio of carboxylated carbon nanotubes, γ-aminopropyltriethoxysilane, tetrahydrofuran, and N,N'-dicyclohexylcarbodiimide is 2-4g:2-4g:80-100mL:0.1-0.2g. The post-treatment step includes: after the reaction is complete, filtration is performed, the filter cake is washed 2-4 times with tetrahydrofuran and anhydrous ethanol, transferred to an oven at 50-60℃, and dried to constant weight to obtain the modified POSS precursor; in step B2, the modified POSS precursor, deionized carbon nanotubes, γ-aminopropyltriethoxysilane, tetrahydrofuran, and N,N'-dicyclohexylcarbodiimide are used in the process. The ratio of aqueous solution, dimethyl sulfoxide, γ-mercaptopropyltriethoxysilane, γ-aminopropyltriethoxysilane, and ammonium fluoride is 4-6 g: 8-10 mL: 150-200 mL: 2-4 g: 2-4 g: 0.4-0.6 g. The post-processing steps include: after the reaction is completed, the product is transferred to an oven at 70-80°C and aged for 5-7 days. After cooling, it is filtered. The filter cake is washed 2-4 times with anhydrous ethanol, transferred to an oven at 50-60°C, and dried to constant weight to obtain modified POSS.

[0043] The present invention also proposes a low-smoke halogen-free aging-resistant insulated cable, which is prepared by the above-mentioned preparation method of a low-smoke halogen-free aging-resistant insulated cable.

[0044] The present invention has the following beneficial effects:

[0045] 1. This invention involves reacting carboxylated carbon nanotubes with a silane coupling agent to prepare an amino-modified modified POSS precursor. This precursor is then catalyzed by multifunctional silanes and ammonium fluoride to prepare a three-dimensional cage-like modified POSS. The modified POSS, as a functional nanomaterial, is introduced into the sheath layer. Its structure contains both organic functional groups and inorganic silicon-oxygen cages, possessing both the flexibility of organic materials and the thermal stability of inorganic materials. Furthermore, the modified POSS is copolymerized with a phenol-formaldehyde system to form modified microspheres, which are then treated with metal salts to impart excellent thermal properties and flame-retardant synergy. The modified nanoparticles exhibit several effects. First, the silicon-oxygen cage structure of the modified POSS possesses high thermal stability, maintaining structural integrity at high temperatures. Under conditions of sheath melting and long-term service, it effectively inhibits the thermal oxidative degradation of the polymer matrix, slowing down the aging rate and thus improving the heat aging resistance and mechanical properties of the cable sheath. Second, the abundant silicon-oxygen structures in the modified POSS promote char formation and the formation of a dense silica ceramic protective layer during combustion, effectively blocking the propagation of heat and combustible gases, and significantly improving the flame retardant and smoke suppression properties of the sheath.

[0046] 2. This invention involves mixing modified POSS with phenolic resin to prepare modified microspheres, which are then further introduced into a nickel acetate solution for complexation deposition to obtain modified nanoparticles. The surface of the modified nanoparticles contains abundant polar groups that form a good interfacial bond with SBS-g-MAH in the sheath matrix, improving the tensile strength and elongation at break of the insulated cable sheath. Furthermore, these nanoparticles introduce a synergistic flame-retardant system composed of multiple elements such as phosphorus, silicon, and nickel. Among them, phosphorus can inhibit the combustion reaction chain in a fire, nickel promotes the formation and stabilization of the carbon layer during combustion, forming a dense carbonization barrier layer, and silicon can generate silicon dioxide ceramics at high temperatures. The modified nanoparticles further enhance the flame retardant and smoke suppression properties of the sheath layer. Simultaneously, during melt extrusion preparation of the sheath layer, under the action of the initiator, the thiol groups contained in the modified nanoparticles form stable chemical bonds with polypropylene and flame-retardant modified monomers through free radical polymerization and thiol-olefin click reactions. This chemical cross-linking structure significantly improves the thermal stability and inter-chain bonding of the sheath layer material, inhibiting polymer chain breakage and degradation during thermo-oxidative aging. Furthermore, the uniform dispersion of the nanoparticles helps construct a dense three-dimensional network structure, further hindering heat and oxygen conduction, thereby effectively improving the heat aging resistance of the sheath layer material and extending its service life.

[0047] 3. In the preparation of insulated cables, this invention incorporates a flame-retardant modified monomer. This monomer is formed by the condensation of 1,2-epoxy-5-hexene and a phosphorus-containing compound (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-ethanol oxide). The structure introduces active double bonds and phosphorus, resulting in excellent reactivity and flame-retardant properties. During melt extrusion, the flame-retardant modified monomer can undergo grafting or cross-linking reactions with the polypropylene matrix via free radical reactions, forming a chemical bond. This improves the thermal stability and thermo-oxidative aging performance of the sheath material. Simultaneously, phosphorus generates phosphoric acid or polyphosphoric acid during combustion, forming a dense carbonized layer on the material surface. This effectively blocks heat and oxygen conduction, inhibits flame propagation, and enhances the flame-retardant performance of the sheath material. Furthermore, the introduction of this monomer can synergistically work with nanoparticles to construct a highly efficient condensed-phase flame-retardant system, improving the high flame-retardant performance and smoke suppression performance of the sheath material without the presence of halogens. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This is a schematic diagram of the overall cross-sectional structure of the present invention.

[0050] In the diagram: 1. Cable core; 2. Wrapping layer; 3. Filler layer; 4. Sheath layer. Detailed Implementation

[0051] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] The polypropylene used in this invention was purchased from Shanghai Zhongkaitai Plastics Co., Ltd., model SE191, brand LyondellBasell, with a particle size of 25mm.

[0053] The SBS-g-MAH used in this invention was purchased from Dongguan Dayue Plastics Technology Co., Ltd., and its grade is 207-35.

[0054] The cable core used in this invention was purchased from Zhejiang Zhenghe Silicon Materials Co., Ltd., with the grade DY-307 and the appearance of semi-transparent soft rubber granules.

[0055] The wrapping tape used in this invention was purchased from Shenzhen Mingxin Polymer Technology Co., Ltd., with the brand name M111, product name PTFE wrapping tape, and thickness of 0.05-0.6mm;

[0056] The carboxylated carbon nanotubes used in this invention were purchased from Beijing Jinke New Materials Technology Co., Ltd., and have a density of 0.15 g / cm³. 3 The tube diameter is 5-10 nm.

[0057] Example 1

[0058] This embodiment provides a method for preparing modified POSS for use in modified nanoparticles for low-smoke, halogen-free, aging-resistant insulated cables, comprising the following steps:

[0059] Step I: Preparation of modified POSS precursor

[0060] Weigh out 20g of carboxylated carbon nanotubes, 20g of γ-aminopropyltriethoxysilane, 800mL of tetrahydrofuran and 1g of N,N'-dicyclohexylcarbodiimide and place them in a reaction vessel and stir. React at room temperature for 2h. After the reaction is complete, filter the mixture and wash the filter cake twice with tetrahydrofuran and anhydrous ethanol. Transfer the cake to an oven at 50℃ and dry it to constant weight to obtain the modified POSS precursor.

[0061] Step II: Preparation of modified POSS

[0062] Weigh 40g of modified POSS precursor, 80mL of deionized water, and 1500mL of dimethyl sulfoxide into a reaction vessel and stir for 10min. Add 20g of γ-mercaptopropyltriethoxysilane and 20g of γ-aminopropyltriethoxysilane. Heat the reaction vessel to 55℃ and maintain the temperature for 4h. Cool the reaction vessel to room temperature and add 4g of ammonium fluoride. Stir at room temperature for 20h. After the reaction is complete, transfer the product to an oven at 70℃ and age for 5 days. After cooling, filter the product. Wash the filter cake twice with anhydrous ethanol and transfer it to an oven at 50℃. Dry to constant weight to obtain modified POSS.

[0063] Example 2

[0064] This embodiment provides a method for preparing modified POSS for use in modified nanoparticles for low-smoke, halogen-free, aging-resistant insulated cables, comprising the following steps:

[0065] Step I: Preparation of modified POSS precursor

[0066] Weigh out 30g of carboxylated carbon nanotubes, 30g of γ-aminopropyltriethoxysilane, 900mL of tetrahydrofuran, and 1.5g of N,N'-dicyclohexylcarbodiimide and place them in a reaction vessel and stir. React at room temperature for 3h. After the reaction is complete, filter the mixture and wash the filter cake three times with tetrahydrofuran and anhydrous ethanol. Transfer the cake to an oven at 55℃ and dry it to constant weight to obtain the modified POSS precursor.

[0067] Step II: Preparation of modified POSS

[0068] Weigh 50g of modified POSS precursor, 90mL of deionized water, and 1750mL of dimethyl sulfoxide into a reaction vessel and stir for 13min. Add 30g of γ-mercaptopropyltriethoxysilane and 30g of γ-aminopropyltriethoxysilane. Heat the reaction vessel to 60℃ and maintain the temperature for 5h. Cool the reaction vessel to room temperature and add 5g of ammonium fluoride. Stir at room temperature for 22h. After the reaction is complete, transfer the product to an oven at 75℃ and age for 6 days. After cooling, filter the product. Wash the filter cake three times with anhydrous ethanol and transfer it to an oven at 55℃ to dry to constant weight to obtain modified POSS.

[0069] Example 3

[0070] This embodiment provides a method for preparing modified POSS for use in modified nanoparticles for low-smoke, halogen-free, aging-resistant insulated cables, comprising the following steps:

[0071] Step I: Preparation of modified POSS precursor

[0072] Weigh out 40g of carboxylated carbon nanotubes, 40g of γ-aminopropyltriethoxysilane, 1000mL of tetrahydrofuran and 2g of N,N'-dicyclohexylcarbodiimide and place them in a reaction vessel and stir. React at room temperature for 4h. After the reaction is complete, filter the mixture and wash the filter cake 4 times with tetrahydrofuran and anhydrous ethanol. Transfer the cake to an oven at 60℃ and dry it to constant weight to obtain the modified POSS precursor.

[0073] Step II: Preparation of modified POSS

[0074] Weigh 60g of modified POSS precursor, 100mL of deionized water, and 2000mL of dimethyl sulfoxide into a reaction vessel and stir for 15min. Add 40g of γ-mercaptopropyltriethoxysilane and 40g of γ-aminopropyltriethoxysilane. Heat the reaction vessel to 65℃ and maintain the temperature for 6h. Cool the reaction vessel to room temperature and add 6g of ammonium fluoride. Stir at room temperature for 24h. After the reaction is complete, transfer the product to an oven at 80℃ and age for 7 days. After cooling, filter the product. Wash the filter cake 4 times with anhydrous ethanol and transfer it to an oven at 60℃. Dry to constant weight to obtain modified POSS.

[0075] Example 4

[0076] This embodiment provides a method for preparing modified nanoparticles for low-smoke, halogen-free, aging-resistant insulating cables, comprising the following steps:

[0077] Step ①: Preparation of intermediate I

[0078] Weigh 5g of the modified POSS prepared in Example 1 and 500mL of 37wt% formaldehyde aqueous solution and place them in a reaction vessel. Stir at room temperature for 0.5h, add 250g of phenol and 80mL of 2wt% sodium hydroxide aqueous solution, heat the reaction vessel to 75℃ and keep it at that temperature for 4h. After the reaction is complete, transfer the product to an oven with a vacuum degree of 0.09MPa, heat the oven to 70℃ and keep it at that temperature for 1h to obtain intermediate I.

[0079] Step ②: Preparation of intermediate II

[0080] Weigh 50 mL of 37 wt% formaldehyde aqueous solution and place it in a reaction vessel. Stir the reaction vessel and bring it to 0°C in an ice bath. Slowly add 100 g of p-phenol sulfonic acid and stir at room temperature for 15 min to obtain intermediate II.

[0081] Step 3: Preparation of modified microspheres

[0082] Weigh out 50g of intermediate I, 1500mL of deionized water and 200mL of ethanol and place them in a reaction vessel and stir. Add 50g of intermediate II, heat the reaction vessel to 65℃ and keep it at that temperature for 2 hours. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, wash the filter cake twice with deionized water and ethanol, transfer it to an oven at 60℃ and dry it to constant weight to obtain modified microspheres.

[0083] Step 4: Preparation of modified nanoparticles

[0084] Weigh 50g of modified microspheres and 1000mL of deionized water and place them in a reaction vessel and stir. Add 2wt% sodium hydroxide aqueous solution to adjust the pH to 6.5, add 400mL of 20wt% nickel acetate solution, stir at room temperature for 10h, and after the reaction is complete, let stand for 10h, filter, wash the filter cake twice with deionized water, transfer it to an oven at 70℃ and dry it to constant weight to obtain modified nanoparticles.

[0085] Example 5

[0086] This embodiment provides a method for preparing modified nanoparticles for low-smoke, halogen-free, aging-resistant insulating cables, comprising the following steps:

[0087] Step ①: Preparation of intermediate I

[0088] Weigh 7g of the modified POSS prepared in Example 2 and 550mL of 37wt% formaldehyde aqueous solution and place them in a reaction vessel. Stir at room temperature for 1h, add 270g of phenol and 90mL of 3.5wt% sodium hydroxide aqueous solution, heat the reaction vessel to 80℃ and keep it at that temperature for 5h. After the reaction is complete, transfer the product to an oven with a vacuum degree of 0.10MPa, heat the oven to 75℃ and keep it at that temperature for 1.5h to obtain intermediate I.

[0089] Step ②: Preparation of intermediate II

[0090] Weigh 75 mL of 37 wt% formaldehyde aqueous solution and place it in a reaction vessel. Stir the reaction vessel and heat it to 3°C in an ice bath. Slowly add 125 g of p-phenol sulfonic acid and stir at room temperature for 25 min to obtain intermediate II.

[0091] Step 3: Preparation of modified microspheres

[0092] Weigh 70g of intermediate I, 1750mL of deionized water and 225mL of ethanol and place them in a reaction vessel and stir. Add 70g of intermediate II, heat the reaction vessel to 70℃ and keep it at that temperature for 3 hours. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, wash the filter cake three times with deionized water and ethanol, transfer it to an oven at 65℃ and dry it to constant weight to obtain modified microspheres.

[0093] Step 4: Preparation of modified nanoparticles

[0094] Weigh 60g of modified microspheres and 1100mL of deionized water and place them in a reaction vessel and stir. Add 3.5wt% sodium hydroxide aqueous solution to adjust the pH to 7, add 500mL of 25wt% nickel acetate solution, stir at room temperature for 11h, and after the reaction is complete, let stand for 11h, filter, wash the filter cake 3 times with deionized water, transfer it to an oven at 75℃ and dry it to constant weight to obtain modified nanoparticles.

[0095] Example 6

[0096] This embodiment provides a method for preparing modified nanoparticles for low-smoke, halogen-free, aging-resistant insulating cables, comprising the following steps:

[0097] Step ①: Preparation of intermediate I

[0098] Weigh 10g of the modified POSS prepared in Example 3 and 600mL of 37wt% formaldehyde aqueous solution and place them in a reaction vessel. Stir at room temperature for 1h, add 300g of phenol and 100mL of 5wt% sodium hydroxide aqueous solution, heat the reaction vessel to 85℃ and keep it at that temperature for 6h. After the reaction is complete, transfer the product to an oven with a vacuum degree of 0.11MPa, heat the oven to 80℃ and keep it at that temperature for 2h to obtain intermediate I.

[0099] Step ②: Preparation of intermediate II

[0100] Weigh 100 mL of 37 wt% formaldehyde aqueous solution and place it in a reaction vessel. Stir the reaction vessel and heat it to 5°C in an ice bath. Slowly add 150 g of p-phenol sulfonic acid and stir at room temperature for 30 min to obtain intermediate II.

[0101] Step 3: Preparation of modified microspheres

[0102] Weigh 100g of intermediate I, 2000mL of deionized water and 250mL of ethanol and place them in a reaction vessel and stir. Add 100g of intermediate II, heat the reaction vessel to 75℃ and keep it at that temperature for 4 hours. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, wash the filter cake 4 times with deionized water and ethanol, transfer it to an oven at 70℃ and dry it to constant weight to obtain modified microspheres.

[0103] Step 4: Preparation of modified nanoparticles

[0104] Weigh 70g of modified microspheres and 1200mL of deionized water and place them in a reaction vessel and stir. Add 5wt% sodium hydroxide aqueous solution to adjust the pH to 7.5, add 600mL of 30wt% nickel acetate solution, stir at room temperature for 12h, and after the reaction is complete, let stand for 12h, filter, wash the filter cake 4 times with deionized water, transfer it to an oven at 80℃ and dry it to constant weight to obtain modified nanoparticles.

[0105] Example 7

[0106] This embodiment provides a method for preparing a low-smoke, halogen-free, aging-resistant insulated cable, including the following steps:

[0107] Step 1: Prepare the cladding layer

[0108] Several cable cores 1 are arranged in parallel, and filler is placed in the gaps between the cable cores 1 to form a filler layer 3. The several cable cores 1 filled with filler layer 3 are wrapped together with wrapping tape to form a wrapping layer 2 on the outside of the several cable cores 1.

[0109] Step 2: Preparation of flame-retardant modified monomers

[0110] Weigh out 30g of 1,2-epoxy-5-hexene, 40g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-ethanol 10-oxide, 4g of aluminum chloride, and 1300mL of tetrahydrofuran and place them in a reaction vessel. Stir the vessel and heat it to 50℃. Keep the temperature for 4 hours. After the reaction is complete, let the reaction system cool to room temperature and slowly add ice water until no more bubbles emerge. Add 2wt% sodium hydroxide aqueous solution until the pH is neutral. Wash the reaction solution twice with ethyl acetate. Transfer the organic phase to a rotary evaporator at 50℃ and evaporate until no liquid is collected to obtain the flame-retardant modified monomer.

[0111] Step 3: Prepare insulated cable

[0112] Dioctyl sebacate, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] and paraffin were mixed evenly in a mass ratio of 4:2:4 to obtain an auxiliary additive for later use.

[0113] Weigh out: 600g of polypropylene, 40g of SBS-g-MAH, 40g of modified nanoparticles prepared in Example 4, 80g of flame-retardant modified monomer, 5g of dicumyl peroxide and 10g of auxiliary additives are mixed and added to a twin-screw extruder. After melting, the mixture is extruded and coated on the outside of the wrapping layer 2 to form the sheath layer 4, thus obtaining an insulated cable.

[0114] The twin-screw extruder has eight temperature zones from the feed inlet to the discharge outlet, with temperatures of 160℃, 160℃, 175℃, 175℃, 190℃, 190℃, 200℃, and 200℃ respectively. The main motor speed of the twin-screw extruder is 120 rpm, and the pressure is 80 bar.

[0115] Example 8

[0116] This embodiment provides a method for preparing a low-smoke, halogen-free, aging-resistant insulated cable, including the following steps:

[0117] Step 1: Prepare the cladding layer

[0118] Several cable cores 1 are arranged in parallel, and filler is placed in the gaps between the cable cores 1 to form a filler layer 3. The several cable cores 1 filled with filler layer 3 are wrapped together with wrapping tape to form a wrapping layer 2 on the outside of the several cable cores 1.

[0119] Step 2: Preparation of flame-retardant modified monomers

[0120] Weigh out 40g of 1,2-epoxy-5-hexene, 50g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-ethanol 10-oxide, 6g of aluminum chloride, and 1400mL of tetrahydrofuran and place them in a reaction vessel. Stir the vessel and heat it to 55℃. Keep the temperature for 5 hours. After the reaction is complete, wait for the reaction system to cool to room temperature and slowly add ice water until no more bubbles emerge. Add 3.5wt% sodium hydroxide aqueous solution until the pH is neutral. Wash the reaction solution three times with ethyl acetate. Transfer the organic phase to a rotary evaporator at 55℃ and evaporate until no liquid is collected to obtain the flame-retardant modified monomer.

[0121] Step 3: Prepare insulated cable

[0122] Dioctyl sebacate, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] and paraffin were mixed evenly in a mass ratio of 4:2:4 to obtain an auxiliary additive for later use.

[0123] Weigh out: 700g of polypropylene, 50g of SBS-g-MAH, 60g of modified nanoparticles prepared in Example 5, 90g of flame-retardant modified monomer, 7g of dicumyl peroxide and 20g of auxiliary additives, mix and add to a twin-screw extruder, melt and extrude to cover the outside of the wrapping layer 2 to form the sheath layer 4, and obtain an insulated cable.

[0124] The twin-screw extruder has eight temperature zones from the feed inlet to the discharge outlet, with temperatures of 160℃, 160℃, 175℃, 175℃, 190℃, 190℃, 200℃, and 200℃ respectively. The main motor speed of the twin-screw extruder is 140 rpm, and the pressure is 100 bar.

[0125] Example 9

[0126] This embodiment provides a method for preparing a low-smoke, halogen-free, aging-resistant insulated cable, including the following steps:

[0127] Step 1: Prepare the cladding layer

[0128] Several cable cores 1 are arranged in parallel, and filler is placed in the gaps between the cable cores 1 to form a filler layer 3. The several cable cores 1 filled with filler layer 3 are wrapped together with wrapping tape to form a wrapping layer 2 on the outside of the several cable cores 1.

[0129] Step 2: Preparation of flame-retardant modified monomers

[0130] Weigh out 50g of 1,2-epoxy-5-hexene, 60g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-ethanol 10-oxide, 8g of aluminum chloride, and 1500mL of tetrahydrofuran and place them in a reaction vessel. Stir the vessel and heat it to 60℃. Keep the temperature for 6 hours. After the reaction is complete, let the reaction system cool to room temperature and slowly add ice water until no more bubbles emerge. Add 5wt% sodium hydroxide aqueous solution until the pH is neutral. Wash the reaction solution with ethyl acetate 4 times. Transfer the organic phase to a rotary evaporator at 60℃ and evaporate until no liquid is collected to obtain the flame-retardant modified monomer.

[0131] Step 3: Prepare insulated cable

[0132] Dioctyl sebacate, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] and paraffin were mixed evenly in a mass ratio of 4:2:4 to obtain an auxiliary additive for later use.

[0133] Weigh out: 800g of polypropylene, 60g of SBS-g-MAH, 70g of modified nanoparticles prepared in Example 6, 100g of flame-retardant modified monomer, 10g of dicumyl peroxide and 30g of auxiliary additives are mixed and added to a twin-screw extruder. After melting, the mixture is extruded and coated on the outside of the wrapping layer 2 to form the sheath layer 4, thus obtaining an insulated cable.

[0134] The twin-screw extruder has eight temperature zones from the feed inlet to the discharge outlet, with temperatures of 160℃, 160℃, 175℃, 175℃, 190℃, 190℃, 200℃, and 200℃ respectively. The main motor speed of the twin-screw extruder is 160 rpm, and the pressure is 120 bar.

[0135] Comparative Example 1

[0136] The difference between this comparative example and Example 9 is that, in step ① when preparing intermediate I, modified POSS is replaced by an equal amount of modified POSS precursor.

[0137] Comparative Example 2

[0138] The difference between this comparative example and Example 9 is that, in step (3) when preparing the insulated cable, modified microspheres are used to replace modified nanoparticles in equal amounts.

[0139] Comparative Example 3

[0140] The difference between this comparative example and Example 9 is that the addition of flame-retardant modified monomer is omitted in step (3) when preparing the insulated cable.

[0141] Performance testing:

[0142] The tensile strength, elongation at break, oxygen index, and smoke density of the sheath layer of the insulated cable samples prepared in Examples 7-9 and Comparative Examples 1-3 were tested in accordance with the standard GB / T 32129-2015 "Halogen-free Low-smoke Flame-retardant Cable Material for Wires and Cables".

[0143] The insulation cable samples prepared in Examples 7-9 and Comparative Examples 1-3 were subjected to thermal aging tests in accordance with the standard GB / T 2951.12-2008 "General Test Methods for Insulation and Sheath Materials of Cables and Optical Fibers - Part 12: General Test Methods - Thermal Aging Test Method". The tensile strength and elongation at break of the insulation cable sample sheath after the thermal aging test were tested in accordance with the standard GB / T 32129-2015. The specific data are shown in Table 1.

[0144] Table 1 - Performance Test Data for Each Sample

[0145]

[0146] Data Analysis:

[0147] Comparative analysis of the data in Table 1 reveals that the sheath layer of the insulated cable sample prepared by this invention exhibits a tensile strength of 15.9 MPa, an elongation at break of 354%, an oxygen index of 38%, a smoke density of 112% with flame, and a smoke density of 45% without flame. Furthermore, after thermal aging, the tensile strength is 14.1 MPa and the elongation at break is 339%. All these data are superior to the comparative example. Therefore, this invention prepares a three-dimensional cage-like structure by reacting carboxylated carbon nanotubes with a silane coupling agent to obtain an amino-modified modified POSS precursor, followed by catalytic treatment with multifunctional silanes and ammonium fluoride. The modified POSS structure is obtained by mixing modified POSS with phenolic resin to prepare modified microspheres, which are then further introduced into nickel acetate solution for complexation deposition to obtain modified nanoparticles. When preparing insulated cables, flame-retardant modified monomers are added. Polypropylene, SBS-g-MAH, modified nanoparticles, flame-retardant modified monomers, initiators and auxiliary additives are mixed and added to a twin-screw extruder. After melting, it is extruded to cover the outside of the wrapping layer to form a sheath layer, thus obtaining an insulated cable. This not only improves the smoke suppression and flame retardant properties of the insulated cable sheath layer, but also improves the mechanical properties and heat aging resistance of the cable sheath layer.

[0148] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a low-smoke, halogen-free, aging-resistant insulated cable, characterized in that, Includes the following steps: S1. Arrange several cable cores (1) in parallel and fill the gaps between the cable cores (1) to form a filling layer (3). Use wrapping tape to wrap the several cable cores (1) filled with the filling layer (3) together to form a wrapping layer (2) on the outside of the several cable cores (1). S2. 1,2-Epoxy-5-hexene, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-ethanol 10-oxide, aluminum chloride and tetrahydrofuran are placed in a reaction vessel and stirred. The reaction vessel is heated to 50-60℃ and kept at the temperature for 4-6 hours. The flame-retardant modified monomer is obtained after post-treatment. S3. Polypropylene, SBS-g-MAH, modified nanoparticles, flame-retardant modified monomers, initiators and auxiliary additives are mixed and added to a twin-screw extruder. After melting, they are extruded and wrapped around the outside of the wrapping layer (2) to form a sheath layer (4) to obtain an insulated cable.

2. The method for preparing a low-smoke, halogen-free, aging-resistant insulated cable according to claim 1, characterized in that, In step S2, the ratio of 1,2-epoxy-5-hexene, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-ethanol 10-oxide, aluminum chloride, and tetrahydrofuran is 3-5g:4-6g:0.4-0.8g:130-150mL; in step S3, the weight ratio of polypropylene, maleic anhydride-modified polyethylene, modified nanoparticles, flame-retardant modified monomer, initiator, and auxiliary additives is 60-80:4-6:4-7:8-10:0.5-1:1-3, and the initiator is dicumyl peroxide.

3. The method for preparing a low-smoke, halogen-free, aging-resistant insulated cable according to claim 1, characterized in that, The modified nanoparticles are prepared by: placing modified microspheres and deionized water in a reaction vessel and stirring, adding sodium hydroxide aqueous solution to adjust the pH to 7±0.5, adding nickel acetate solution, stirring at room temperature for 10-12 hours, and then performing post-treatment to obtain modified nanoparticles.

4. The method for preparing a low-smoke, halogen-free, aging-resistant insulated cable according to claim 3, characterized in that, The ratio of the modified microspheres, deionized water, and nickel acetate solution is 5-7g:100-120mL:40-60mL, the concentration of the sodium hydroxide aqueous solution is 2-5wt%, and the concentration of the nickel acetate solution is 20-30wt%.

5. The method for preparing a low-smoke, halogen-free, aging-resistant insulated cable according to claim 3, characterized in that, The modified microspheres were prepared by the following steps: A1. Place the modified POSS and formaldehyde aqueous solution in a reaction vessel and stir at room temperature for 0.5-1h. Add phenol and sodium hydroxide aqueous solution, heat the reaction vessel to 75-85℃, and keep it at this temperature for 4-6h. After post-treatment, obtain intermediate I. A2. Place the formaldehyde aqueous solution in a reaction vessel and stir. Keep the reaction vessel in an ice bath at 0-5°C. Slowly add p-phenol sulfonic acid and stir at room temperature for 15-30 minutes to obtain intermediate II. A3. Place intermediate I, deionized water and ethanol in a reaction vessel and stir. Add intermediate II, heat the reaction vessel to 65-75℃, and keep the reaction at this temperature for 2-4 hours. After post-treatment, the modified microspheres are obtained.

6. The method for preparing a low-smoke, halogen-free, aging-resistant insulated cable according to claim 5, characterized in that, In step A1, the ratio of modified POSS, formaldehyde aqueous solution, phenol, and sodium hydroxide aqueous solution is 0.5-1g:50-60mL:25-30g:8-10mL, the concentration of the formaldehyde aqueous solution is 37wt%, and the concentration of the sodium hydroxide aqueous solution is 2-5wt%; in step A2, the ratio of formaldehyde aqueous solution to p-phenolsulfonic acid is 5-10mL:10-15g, and the concentration of the formaldehyde aqueous solution is 37wt%; in step A3, the ratio of intermediate I, deionized water, ethanol, and intermediate II is 5-10g:150-200mL:20-25mL:5-10g.

7. The method for preparing a low-smoke, halogen-free, aging-resistant insulated cable according to claim 5, characterized in that, The modified POSS is prepared by the following steps: B1. Carboxylated carbon nanotubes, γ-aminopropyltriethoxysilane, tetrahydrofuran and N,N'-dicyclohexylcarbodiimide were placed in a reaction vessel and stirred. The mixture was reacted at room temperature for 2-4 hours. The modified POSS precursor was obtained after post-treatment. B2. Place the modified POSS precursor, deionized water, and dimethyl sulfoxide in a reaction vessel and stir for 10-15 min. Add γ-mercaptopropyltriethoxysilane and γ-aminopropyltriethoxysilane. Heat the reaction vessel to 55-65℃ and maintain the temperature for 4-6 h. Cool the reaction vessel to room temperature, add ammonium fluoride, and stir at room temperature for 20-24 h. Post-treatment yields the modified POSS.

8. The method for preparing a low-smoke, halogen-free, aging-resistant insulated cable according to claim 7, characterized in that, In step B1, the ratio of carboxylated carbon nanotubes, γ-aminopropyltriethoxysilane, tetrahydrofuran, and N,N'-dicyclohexylcarbodiimide is 2-4g:2-4g:80-100mL:0.1-0.2g; in step B2, the ratio of modified POSS precursor, deionized water, dimethyl sulfoxide, γ-mercaptopropyltriethoxysilane, γ-aminopropyltriethoxysilane, and ammonium fluoride is 4-6g:8-10mL:150-200mL:2-4g:2-4g:0.4-0.6g.

9. A low-smoke, halogen-free, aging-resistant insulated cable, characterized in that, The low-smoke halogen-free aging-resistant insulated cable is prepared using the method described in any one of claims 1-8.

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