Controllable preparation method of multi-morphology nano magnesium carbonate and application of multi-morphology nano magnesium carbonate in synergistic flame-retardant-enhanced cable belting

Abstract

The invention discloses a controllable preparation method of multi-morphology nano magnesium carbonate and application of the multi-morphology nano magnesium carbonate in a synergistic flame-retardant-enhanced cable belting, and belongs to the technical field of inorganic functional materials and flame-retardant composite materials. Magnesium carbonate trihydrate nanofibers and flower clusters are compounded according to the mass ratio of 1: 1 to serve as a novel flame retardant applied to the field of cable wrapping, and the novel flame retardant is different from conventional halogen-free flame retardants such as mainstream magnesium hydroxide and aluminum hydroxide. Magnesium carbonate trihydrate is decomposed, absorbs heat and releases water and carbon dioxide at high temperature, and has a very good flame-retardant mechanism. The fibrous and flower-cluster-shaped nano magnesium carbonate trihydrate is prepared through process control instead of common granular magnesium carbonate. According to the compounded nano magnesium carbonate, on one hand, nano magnesium carbonate fibers can better play a role in strengthening and toughening (similar to crystal whiskers), and on the other hand, the specific surface area of a nano magnesium carbonate flower cluster surface is larger, so that gas adsorption and thermal decomposition are promoted, and the exertion of a flame-retardant effect is facilitated.

Description

Technical Field

[0001] This invention relates to a controllable preparation method of multimorphic nano-magnesium carbonate and its application in synergistic flame-retardant and reinforced cable wrapping tape. Specifically, it relates to a preparation method of nano-magnesium carbonate with controllable morphology and its application as a synergistic flame-retardant and reinforced filler in halogen-free flame-retardant cable wrapping tape, belonging to the technical field of inorganic functional materials and flame-retardant composite materials. Background Technology

[0002] According to statistics from the fire department, approximately 80% of fire accidents in China each year are caused by electrical faults, with more than half of these related to electrical wires and cables. A significant contributing factor to these accidents is the use of flammable materials in the cable manufacturing process, or the release of toxic and harmful gases during combustion. These materials not only accelerate the spread of fire, but the resulting dense smoke and toxic gases also hinder evacuation, seriously threatening lives and causing substantial socio-economic losses. Therefore, developing high-performance flame-retardant cable materials and improving their fire safety is of great importance for ensuring public safety and promoting sustainable industrial development, and has become a key research direction.

[0003] The structure of a power cable typically consists of an inner copper conductor, an insulation layer, a flame-retardant filler rope, a wrapping layer, a steel tape armor layer, and a sheath. This invention relates to flame-retardant and fire-resistant wrapping tape material, an important component of cables.

[0004] Chinese patent application CN201910485966.7 discloses a halogen-free flame-retardant cable wrapping tape and its preparation method. This flame-retardant tape uses magnesium carbonate trihydrate fiber as the main flame-retardant material. The formulation system uses 20-40 parts by weight of EVA and LLDPE blend as the matrix, and adds 50-70 parts by weight of magnesium carbonate trihydrate fiber surface-treated with a silane coupling agent, significantly improving interfacial bonding. Additionally, 5-15 parts by weight of microencapsulated red phosphorus is added as a synergistic flame retardant, improving flame-retardant efficiency while addressing the issues of red phosphorus's hygroscopicity and oxidation. The preparation process covers key steps such as fiber surface treatment, premixing, twin-screw melt blending and granulation, and calendering, ensuring product uniformity and performance stability. The final cable wrapping tape exhibits excellent comprehensive performance: a limiting oxygen index exceeding 45%, achieving a UL-94 V-0 flame retardant rating, high mechanical strength, excellent tear resistance, and environmentally friendly characteristics such as halogen-free, low smoke, and low toxicity.

[0005] Chinese patent CN202010620384.0 discloses a ceramicized halogen-free flame-retardant cable wrapping tape and its preparation method. The tape uses an EVA / POE polymer matrix, adds surface-treated magnesium carbonate trihydrate fibers as a flame-retardant skeleton, and introduces specific low-temperature ceramic additives such as glass powder. These additives are melted at high temperature, sintering the residue after fiber decomposition into a ceramic layer. It is prepared through a process of intensive mixing, extrusion granulation, and calendering. It not only possesses excellent halogen-free flame-retardant properties but also outstanding fire resistance, forming a heat-insulating ceramic layer in a fire to ensure critical power transmission.

[0006] Chinese patent application CN202110332158.0 discloses a white halogen-free high-strength flame-retardant cable wrapping tape and its preparation method. This flame-retardant tape uses magnesium carbonate trihydrate fiber as the core flame-retardant reinforcing material, combined with aluminum hypophosphite / diethylaluminum hypophosphite and zinc borate to form a white synergistic flame-retardant system. Nano-silica is added to enhance performance, and silicone masterbatch is introduced to significantly improve processing fluidity. Through optimized preparation processes, including fiber surface treatment, precision mixing, extrusion granulation, and calendering, a white wrapping tape product with excellent comprehensive performance is finally obtained. This product not only maintains a high flame-retardant rating and mechanical strength but also achieves adjustable color and improved processing performance, making it particularly suitable for high-end applications where color and appearance are critical.

[0007] In the prior art, patents such as CN201910485966.7, CN202010620384.0, and CN202110332158.0 all use magnesium carbonate trihydrate fiber as a flame retardant filler and improve its compatibility with the polymer matrix through surface treatment.

[0008] However, these existing technologies share the following common problems: 1. Flame retardants have a single form, making it difficult to simultaneously achieve high flame retardancy efficiency and mechanical reinforcement; 2. High addition levels can easily lead to agglomeration, resulting in interface defects and decreased mechanical properties; 3. The lack of systematic regulation of magnesium carbonate crystal morphology prevents the full realization of its multidimensional functional potential; 4. It is difficult to achieve both flame retardancy and reinforcing properties, and the flexibility and strength of the material are significantly deteriorated under high filler content. Summary of the Invention

[0009] The present invention aims to provide a method for controllably preparing nano-magnesium carbonate with various morphologies, and to use it to develop a flame-retardant cable wrapping tape with both high flame retardancy and excellent mechanical properties, thereby resolving the technical contradiction of "high filling-performance degradation" in the prior art.

[0010] Meanwhile, this invention provides a controllable preparation method for multimorphic nano-magnesium carbonate and its application in synergistic flame-retardant-reinforced cable wrapping.

[0011] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A controllable preparation method for multimorphic nano-magnesium carbonate, comprising the following steps: Step 1: Magnesium sulfate heptahydrate is used as the magnesium source, and potassium carbonate is used as the precipitant, with a molar ratio of 3:1. The concentrations of magnesium sulfate heptahydrate are 0.8-1.2 mol / L (nanofibers) and 0.1-0.5 mol / L (nanofibers), respectively. The reaction is carried out at 45-50℃ for 30-40 minutes. (Before adding potassium carbonate, the magnesium source is first added with a mass equal to the Mg content of magnesium sulfate heptahydrate.) 2+ Tea saponin, which is completely converted to 3% of the theoretical mass of magnesium carbonate trihydrate, is used as a crystal form control agent. After the reaction, the solution is filtered through filter paper and repeatedly washed with deionized water to remove impurities. The washed sample is then dried in a forced-air drying oven at 80-90℃ for 2-3 hours to obtain magnesium carbonate trihydrate nanofibers and magnesium carbonate trihydrate nanofloral clusters, respectively.

[0012] Step two: Mix the prepared magnesium carbonate trihydrate nanofibers (5-10g) and magnesium carbonate trihydrate nanofloral clusters (5-10g) at a mass ratio of 1:1, referred to as magnesium carbonate trihydrate FF, and add them to 100-120 mL of anhydrous ethanol, stirring until uniformly mixed. Then, weigh out 1-2% of the mass of magnesium carbonate trihydrate silane coupling agent, mix it with deionized water at a volume ratio of 1:2, and after thorough hydrolysis, add it to the above magnesium carbonate trihydrate / ethanol mixture. Place the mixture in an ultrasonic disperser for 10-15 minutes (power 80-100Hz, temperature 50-60℃) to ensure thorough dispersion and surface reaction. After the reaction, filter the mixture, collect the solid product, and place it in a forced-air drying oven at 80-90℃ for 2-3 hours to finally obtain modified magnesium carbonate trihydrate mixed powder.

[0013] Step 3: Add 6.5-9.5 g of attapulgite to a beaker and dissolve it in 50-80 mL of deionized water. Place a rotor in the beaker and stir at 1000-1500 r / min until the solution reaches a homogeneous viscous state. Then, add 3-6 g of modified magnesium carbonate trihydrate FF mixed powder, remove the rotor, and stir with a glass rod for 15-30 minutes to ensure the mixture is thoroughly and evenly mixed. Finally, add 10-14 g of EVA latex and continue stirring with a glass rod for 15-20 minutes until the adhesive is completely and evenly mixed to obtain a slurry.

[0014] Step 4: Cut a 90mm long and 20mm wide piece of fiberglass cloth as the base for the strap. Apply the slurry to both sides of the fiberglass cloth strip by brushing. After brushing evenly in one go, place it in a petri dish lined with a sample bag and prepare to put it into a forced-air drying oven.

[0015] Step 5: Before drying, turn on the oven to preheat it and set the temperature to 80-90℃. Place the coated sample in the oven and observe the changes on the surface of the packaging during the drying process. Avoid drying for too long, which may cause the coating on the sample surface to crack. The drying time for one coating is approximately 40-45 minutes.

[0016] Note: Applying the coating once results in a thin coating on the sample surface, which often makes it difficult to achieve good flame retardant effect and mechanical properties. Therefore, repeat the above steps and apply the coating three times. The final thickness of the flame retardant tape is about 0.5-0.7 mm, while maintaining good flexibility.

[0017] A novel halogen-free cable wrapping material (i.e., a synergistic flame-retardant and reinforced cable wrapping material) is prepared using a co-precipitation method to prepare the nano-sized magnesium carbonate nanofibers and nanofloral clusters in a 1:1 mass ratio as a flame-retardant material. The surface of the nanofibers and clusters is then modified using a silane coupling agent. The modified magnesium carbonate nanopowder is then mixed with attapulgite clay and EVA latex is added. Using a 90mm × 20mm glass fiber cloth as a substrate, the slurry is uniformly coated onto both sides using a brushing method. After each coating, the material is dried in an 80-90℃ forced-air drying oven for approximately 40-45 minutes. To improve the coating thickness and performance, the coating is repeated three times, ultimately yielding a wrapping material with a thickness of approximately 0.5-0.7mm, exhibiting uniformity, density, good flexibility, and flame-retardant properties. The wrapping material of this invention has an LOI of 63.9-65.1% and a tensile strength of 40-41.44 MPa.

[0018] Application of a controllable preparation method for multimorphic nano-magnesium carbonate in synergistic flame-retardant-reinforced cable wrapping.

[0019] Application of a synergistic flame-retardant-reinforced cable wrap in power cables.

[0020] An electrical cable comprising the synergistic flame-retardant-enhanced cable wrapping of the present invention.

[0021] This invention utilizes a novel flame retardant, combining magnesium carbonate trihydrate nanofibers and flower clusters in a 1:1 mass ratio, for cable wrapping applications. This differs from mainstream halogen-free flame retardants such as magnesium hydroxide and aluminum hydroxide. Magnesium carbonate trihydrate decomposes at high temperatures, absorbing heat and releasing water and carbon dioxide, exhibiting a superior flame-retardant mechanism. Instead of using ordinary granular magnesium carbonate, fibrous and flower-like nano-magnesium carbonate is prepared through controlled processes. The combined nano-magnesium carbonate allows the nanofibers to better enhance and toughen the fibers (similar to whiskers), while the larger surface area of ​​the nano-magnesium carbonate flower clusters promotes gas adsorption and thermal decomposition, further facilitating the flame-retardant effect.

[0022] The core innovation of this invention lies in resolving the contradiction between "high addition amount" and "deterioration of mechanical properties" in the field of halogen-free flame retardants. Through both fiber morphology and surface modification, the flame retardant is no longer simply a "filler" but also becomes a reinforcing material. The modified magnesium carbonate trihydrate fiber bonds more firmly with the polymer matrix (EVA), effectively transferring and bearing stress during tension, thereby significantly improving the material's mechanical strength while enhancing flame retardancy.

[0023] This invention enables the controllable preparation of multi-morphological nano-magnesium carbonate. The raw materials are: magnesium sulfate heptahydrate (magnesium source), potassium carbonate (precipitant), and tea saponin (morphology modifier). Choosing tea saponin offers the following advantages: Bio-based and environmentally friendly: Tea saponin is a natural glycoside compound extracted from plants of the Theaceae family, and is an excellent natural nonionic surfactant. This aligns perfectly with the "green process" principle of this invention, and offers greater environmental advantages compared to petroleum-based SDBS.

[0024] Unique molecular structure: Tea saponin's molecular structure contains hydrophobic triterpenoid saponins and hydrophilic sugar chains. This structure allows it to not only adsorb onto specific crystal faces through electrostatic interactions and steric hindrance, but its large, rigid hydrophobic groups can also more precisely control the anisotropic growth of crystals through steric hindrance, a capability not possessed by traditional linear surfactants (such as SDBS).

[0025] This invention uses tea saponin to prepare fibers with a rougher surface, branched structure, or smaller size, thereby further increasing the specific surface area and enhancing the mechanical interlocking (anchoring) effect with the polymer matrix, thus bringing additional improvements in mechanical properties.

[0026] The process of this invention: By controlling the concentration of reactants, temperature and the amount of crystal form control agent, the morphological transformation from flower clusters to fibers is achieved; Flower-shaped porous microspheres were obtained under low concentration (0.1-0.5 mol / L) conditions of magnesium sulfate heptahydrate, which have high specific surface area and gas adsorption capacity, and enhance flame retardant and smoke suppression effects. Magnesium sulfate heptahydrate is prepared under high concentration (0.8-1.2 mol / L) conditions to obtain fibrous crystals, which have high aspect ratio and reinforcing potential, thus improving mechanical strength; Surface modification: Silane coupling agent is used for interface modification to form Si–O–Mg covalent bonds, thereby improving the bonding force with the polymer matrix.

[0027] The present invention has the following beneficial effects: Morphology-controlled synthesis: By precisely controlling the crystal growth path of nano-magnesium carbonate through reaction conditions, morphological diversity can be achieved from 0D flower clusters to 1D fibers. Multimorphic compounding strategy: Combining flower cluster-shaped (high specific surface area) and fibrous (high reinforcement) nano-magnesium carbonate in an optimized ratio to achieve synergistic improvement in flame retardancy and mechanical properties; Interface enhancement mechanism: By constructing a robust organic-inorganic interface through surface modification, stress transfer efficiency and tear resistance are significantly improved; Green process: The entire preparation process is halogen-free, low-toxicity, and operates at low temperatures, meeting environmental protection requirements. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments 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.

[0029] Figure 1 This is a flowchart of the controllable preparation method of multimorphic nano-magnesium carbonate according to the present invention; Figure 2 This is an analysis chart of the oxygen index under different addition amounts according to the present invention; Figure 3 These are macroscopic morphology observations after stretching at different amounts of the present invention; Figure 4 The fracture strength of samples with different addition amounts according to the present invention; Figure 5 This is an electron microscope image of the magnesium carbonate trihydrate nanoflora clusters of the present invention; Figure 6 This is an electron microscope image of the magnesium carbonate trihydrate nanofibers of the present invention. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0031] According to embodiments of the present invention, a controllable preparation method for multimorphic nano-magnesium carbonate and its application in synergistic flame-retardant-reinforced cable wrapping are provided. Example 1

[0032] like Figure 1 As shown, a controllable preparation method for multimorphic nano-magnesium carbonate includes the following process steps: Step 1: Magnesium sulfate heptahydrate is used as the magnesium source, and potassium carbonate is used as the precipitant, with a molar ratio of 3:1. The magnesium sulfate heptahydrate concentrations are 1.2 mol / L (nanofibers) and 0.5 mol / L (nanofibers), respectively. The reaction is carried out at 45°C for 30 minutes. (Before adding potassium carbonate, the magnesium source is first added with a mass equal to the Mg content of magnesium sulfate heptahydrate.) 2+Tea saponin, which was completely converted to 3% of the theoretical mass of magnesium carbonate trihydrate, was used as a crystal form control agent. After the reaction, the solution was filtered through filter paper and repeatedly washed with deionized water to remove impurities. The washed sample was dried in an 80℃ forced-air drying oven for 2 hours to obtain magnesium carbonate trihydrate nanofibers and magnesium carbonate trihydrate nanofloral clusters, respectively.

[0033] Step two: Mix the prepared magnesium carbonate trihydrate nanofibers (8g) and magnesium carbonate trihydrate nanoflora clusters (8g), abbreviated as magnesium carbonate trihydrate FF, and add to 100mL of anhydrous ethanol, stirring until uniformly mixed. Then, weigh 1% (by mass) of silane coupling agent (preferably silane coupling agent Si-602), mix with deionized water at a volume ratio of 1:2, and after thorough hydrolysis, add to the above magnesium carbonate trihydrate / ethanol mixture. Place the mixture in an ultrasonic disperser for 10 minutes (80Hz, 50℃) to ensure thorough dispersion and surface reaction. After the reaction, filter the mixture, collect the solid product, and place it in a forced-air drying oven to dry at 80℃ for 2 hours, finally obtaining modified magnesium carbonate trihydrate mixed powder.

[0034] Step 3: Add 9.5 g of attapulgite clay to a beaker and dissolve it in 50 mL of deionized water. Place a rotor in the beaker and stir at 1500 r / min until the solution reaches a uniform viscous state. Then, add 6 g of modified magnesium carbonate trihydrate FF mixed powder, remove the rotor, and stir with a glass rod for 15 minutes to ensure the mixture is thoroughly and evenly mixed. Finally, add 13.35 g of EVA latex and continue stirring with a glass rod for 15 minutes until the adhesive is completely and evenly mixed to obtain the slurry.

[0035] Step 4: Cut a 90mm long and 20mm wide piece of fiberglass cloth as the base for the strap. Apply the slurry to both sides of the fiberglass cloth strip by brushing. After brushing evenly in one go, place it in a petri dish lined with a sample bag and prepare to put it into a forced-air drying oven.

[0036] Step 5: Before drying, preheat the oven to 80℃. Place the coated sample in the oven and observe the changes on the surface of the tape during the drying process. Avoid excessive drying time, which may cause the coating on the sample surface to crack. The drying time for each coating is approximately 40 minutes. Apply three coats in total. The final thickness of the flame-retardant tape is approximately 0.6mm, while maintaining good flexibility.

[0037] Application of a controllable preparation method for multimorphic nano-magnesium carbonate in synergistic flame-retardant-reinforced cable wrapping.

[0038] Application of a synergistic flame-retardant-reinforced cable wrap in power cables.

[0039] An electrical cable comprising the synergistic flame-retardant-enhanced cable wrapping of this embodiment.

[0040] like Figure 2 As shown, the flame retardancy and mechanical properties of flame-retardant cable wrapping tape can be simultaneously enhanced by introducing modified magnesium carbonate trihydrate nanoparticles. In the flame retardant performance evaluation, the limiting oxygen index (LOI) was tested on cable flame-retardant wrapping tapes with 2g, 3g, 4g, and 6g of modified magnesium carbonate trihydrate (corresponding to samples a, b, c, and d), and 6g (sample e), respectively. The results are presented in bar chart form (see...). Figure 2 Analysis showed that when the amount of modified magnesium carbonate trihydrate added was 6g, the LOI reached a maximum of 65.1%, significantly better than the national standard (≥45%). Furthermore, further increasing the amount added did not improve the LOI further, indicating that there is a limit to the performance of this flame-retardant system.

[0041] The preparation method of sample a is as follows: Step 1: Magnesium sulfate heptahydrate was used as the magnesium source, and potassium carbonate as the precipitant, with a molar ratio of 3:1. The magnesium sulfate heptahydrate was used at concentrations of 1.2 mol / L (nanofibers) and 0.5 mol / L (nanofibers), respectively, and reacted at 45°C for 30 minutes (before adding potassium carbonate, 3% of the theoretical yield of tea saponin was added to the magnesium source as a crystal form control agent). After the reaction, the solution was filtered through filter paper and repeatedly washed with deionized water to remove impurities. The washed samples were dried in an 80°C forced-air drying oven for 2 hours to obtain magnesium carbonate trihydrate nanofibers and magnesium carbonate trihydrate nanofloral clusters, respectively.

[0042] Step 2: Mix the prepared magnesium carbonate trihydrate nanofibers and magnesium carbonate trihydrate nanofloral clusters at a mass ratio of 1:1, referred to as magnesium carbonate trihydrate.

[0043] Step 3: Add 9.5 g of attapulgite clay to a beaker and dissolve it in 50 mL of deionized water. Place a rotor in the beaker and stir at 1500 r / min until the solution reaches a homogeneous viscous state. Then, add 2 g of magnesium carbonate trihydrate, remove the rotor, and stir with a glass rod for 15 minutes to ensure the mixture is thoroughly and evenly combined. Finally, add 13.35 g of EVA latex and continue stirring with a glass rod for 15 minutes until the adhesive is completely and evenly mixed to obtain the slurry.

[0044] Step 4: Cut a 90mm long and 20mm wide piece of fiberglass cloth as the base for the strap. Apply the slurry to both sides of the fiberglass cloth strip by brushing. After brushing evenly in one go, place it on a petri dish lined with a sample bag and prepare to put it into a forced-air drying oven.

[0045] Step 5: Before drying, preheat the oven to 80℃. Place the coated sample in the oven and observe the changes on the surface of the tape during the drying process. Avoid excessive drying time, which may cause the coating on the sample surface to crack. The drying time for one coat is approximately 40 minutes. Repeat the coating three times. The final thickness of the flame-retardant tape is approximately 0.6 mm.

[0046] The preparation method of sample b is the same as that of sample a, the only difference being that in step three, the amount of magnesium carbonate trihydrate added is 3g.

[0047] The preparation method of sample c is the same as that of sample a, the only difference being that in step three, the amount of magnesium carbonate trihydrate added is 4g.

[0048] The preparation method of sample d is the same as that of sample a, the only difference being that in step three, the amount of magnesium carbonate trihydrate added is 6g.

[0049] like Figure 3 As shown in the figure, tensile properties of flame-retardant cable wrapping tapes with different amounts of magnesium carbonate trihydrate compound powder were analyzed (addition amounts of 2g, 3g, 4g, and 6g, corresponding to samples a and b, and 6g of modified fiber sample e). The fracture morphology characteristics are shown in the figure. When 6g of ordinary fiber and 6g of modified fiber were added, the fracture surface showed a relatively smooth morphology, and obvious glass fiber pull-out effect could be observed.

[0050] like Figure 4 As shown, mechanical property test data also indicate that the tensile strength initially increases and then decreases with increasing addition amount. A peak strength of 34.7 MPa is achieved with the addition of 4g of fiber, while the strength drops to 33.89 MPa due to agglomeration effect when 6g of unmodified powder is added. Notably, the 6g mixed powder sample (e) with surface modification exhibits a significant reinforcing effect, with tensile strength jumping to 41.44 MPa. This phenomenon confirms that the silane coupling agent, by forming Si-O-Mg chemical bonds, constructs an effective interfacial bridge between the magnesium carbonate mixed powder and the matrix, thereby significantly improving the load-bearing capacity of the composite material. Therefore, the mixed powder of magnesium carbonate trihydrate nanofibers and nanofloral clusters is a highly efficient filler with both flame-retardant and reinforcing functions. Under optimal addition amount (6g) and surface modification conditions, it can simultaneously achieve high flame retardancy (LOI=65.1%) and high mechanical strength (41.44 MPa) in the packaging.

[0051] like Figure 5As shown, electron microscopy characterization revealed that the concentration of magnesium carbonate trihydrate significantly modulates the morphology of the product. At a concentration of 0.5 mol / L, the product exhibits a unique flower-like morphology (Fig. a), with its main body composed of porous sheets assembled into regular spheres with an average particle size of approximately 5 μm. The surface of the spheres is densely covered with groove-like micro / nano structures, forming rich three-dimensional hierarchical interfaces, significantly increasing the specific surface area of ​​the material. Figure 6 As shown, when the concentration is increased to 1.2 mol / L, the crystal growth habit changes, and the product exhibits a typical one-dimensional fibrous morphology (Figure b). The aspect ratio of the fibers is concentrated in the range of 10~30, the surface is smooth and flat with high crystallinity and no obvious defects, indicating that the crystals preferentially grow along the c-axis at this concentration, which is consistent with the intrinsic crystallization characteristics of magnesium carbonate trihydrate. Example 2

[0052] A controllable preparation method for multimorphic nano-magnesium carbonate, comprising the following steps: Step 1: Magnesium sulfate heptahydrate is used as the magnesium source, and potassium carbonate is used as the precipitant, with a molar ratio of 3:1. The magnesium sulfate heptahydrate concentrations are 0.8 mol / L (nanofibers) and 0.1 mol / L (nanofibers), respectively. The reaction is carried out at 50°C for 40 minutes. (Before adding potassium carbonate, the magnesium source is first added with a mass equal to the Mg content of magnesium sulfate heptahydrate.) 2+ Tea saponin, which was completely converted to 3% of the theoretical mass of magnesium carbonate trihydrate, was used as a crystal form control agent. After the reaction, the solution was filtered through filter paper and repeatedly washed with deionized water to remove impurities. The washed sample was dried in a 90℃ forced-air drying oven for 3 hours to obtain magnesium carbonate trihydrate nanofibers and magnesium carbonate trihydrate nanofloral clusters, respectively.

[0053] Step two: The prepared magnesium carbonate trihydrate nanofibers (5g) and magnesium carbonate trihydrate nanofloral clusters (5g) were mixed at a mass ratio of 1:1, referred to as magnesium carbonate trihydrate FF, and added to 120 mL of anhydrous ethanol, stirring until homogeneous. Then, 2% (by mass) of silane coupling agent was weighed and mixed with deionized water at a volume ratio of 1:2. After complete hydrolysis, this mixture was added to the above magnesium carbonate trihydrate / ethanol mixture. The mixture was then treated in an ultrasonic disperser for 15 minutes (100Hz, 60℃) to ensure thorough dispersion and surface reaction. After the reaction, the mixture was filtered, the solid product was collected, and dried in a forced-air drying oven at 90℃ for 3 hours to obtain the modified magnesium carbonate trihydrate mixed powder.

[0054] Step 3: Add 6.5g of attapulgite clay to a beaker and dissolve it in 80mL of deionized water. Place a rotor in the beaker and stir at 1000 rpm until the solution reaches a uniform viscous state. Then, add 3g of modified magnesium carbonate trihydrate FF mixed powder, remove the rotor, and stir with a glass rod for 30 minutes to ensure the mixture is thoroughly and evenly mixed. Finally, add 10g of EVA latex and continue stirring with a glass rod for 20 minutes until the adhesive is completely and evenly mixed to obtain the slurry.

[0055] Step 4: Cut a 90mm long and 20mm wide piece of fiberglass cloth as the base for the strap. Apply the slurry to both sides of the fiberglass cloth strip by brushing. After brushing evenly in one go, place it in a petri dish lined with a sample bag and prepare to put it into a forced-air drying oven.

[0056] Step 5: Before drying, preheat the oven to 90℃. Place the coated sample in the oven and observe the changes on the surface of the tape during the drying process. Avoid excessive drying time, which may cause the coating on the sample surface to crack. The drying time for one coat is approximately 45 minutes. Apply three coats. The final thickness of the flame-retardant tape is approximately 0.7mm, while maintaining good flexibility.

[0057] A novel halogen-free cable wrapping material (i.e., a synergistic flame-retardant and reinforced cable wrapping material) is prepared by co-precipitation of magnesium carbonate trihydrate nanofibers and nanofloral clusters in a 1:1 mass ratio. The surface of the nanofibers and clusters is then modified using a silane coupling agent. The modified magnesium carbonate nanopowder is then mixed with attapulgite clay and EVA latex. Using a 90mm × 20mm glass fiber cloth as a substrate, the slurry is uniformly coated onto both sides using a brushing method. After each coating, the material is dried in a 90℃ forced-air drying oven for approximately 45 minutes. To improve the coating thickness and performance, the coating is repeated three times, ultimately yielding a wrapping material with a thickness of approximately 0.7mm, exhibiting uniformity, density, good flexibility, and flame retardant properties. The wrapping material obtained in this embodiment exhibits high flame retardancy (LOI = 64.5%) and high mechanical strength (40.12 MPa).

[0058] Application of a controllable preparation method for multimorphic nano-magnesium carbonate in synergistic flame-retardant-reinforced cable wrapping.

[0059] Application of a synergistic flame-retardant-reinforced cable wrap in power cables.

[0060] An electrical cable comprising the synergistic flame-retardant-enhanced cable wrapping of the present invention. Example 3

[0061] A controllable preparation method for multimorphic nano-magnesium carbonate, comprising the following steps: Step 1: Magnesium sulfate heptahydrate is used as the magnesium source, and potassium carbonate is used as the precipitant, with a molar ratio of 3:1. The magnesium sulfate heptahydrate concentrations are 1.0 mol / L (nanofibers) and 0.3 mol / L (nanofibers), respectively. The reaction is carried out at 45°C for 35 minutes. (Before adding potassium carbonate, the magnesium source is first added with a mass equal to the Mg content of magnesium sulfate heptahydrate.) 2+ Tea saponin, which was completely converted to 3% of the theoretical mass of magnesium carbonate trihydrate, was used as a crystal form control agent. After the reaction, the solution was filtered through filter paper and repeatedly washed with deionized water to remove impurities. The washed sample was dried in an 85℃ forced-air drying oven for 2.5 hours to obtain magnesium carbonate trihydrate nanofibers and magnesium carbonate trihydrate nanofloral clusters, respectively.

[0062] Step two: The prepared magnesium carbonate trihydrate nanofibers (10g) and magnesium carbonate trihydrate nanofloral clusters (10g) were mixed at a mass ratio of 1:1, referred to as magnesium carbonate trihydrate FF, and added to 110mL of anhydrous ethanol, stirring until uniformly mixed. Then, 1.5% of the mass of magnesium carbonate trihydrate silane coupling agent was weighed and mixed with deionized water at a volume ratio of 1:2. After complete hydrolysis, this mixture was added to the above magnesium carbonate trihydrate / ethanol mixture. The mixture was then treated in an ultrasonic disperser for 12 minutes (90Hz, 55℃) to ensure thorough dispersion and surface reaction. After the reaction, the mixture was filtered, the solid product was collected, and dried in a forced-air drying oven at 85℃ for 2.5 hours to finally obtain modified magnesium carbonate trihydrate mixed powder.

[0063] Step 3: Add 8g of attapulgite clay to a beaker and dissolve it in 60mL of deionized water. Place a rotor in the beaker and stir at 1200 rpm until the solution reaches a uniform viscous state. Then, add 5g of modified magnesium carbonate trihydrate FF mixed powder, remove the rotor, and stir with a glass rod for 20 minutes to ensure the mixture is thoroughly and evenly mixed. Finally, add 11g of EVA latex and continue stirring with a glass rod for 18 minutes until the adhesive is completely and evenly mixed to obtain the slurry.

[0064] Step 4: Cut a 90mm long and 20mm wide piece of fiberglass cloth as the base for the strap. Apply the slurry to both sides of the fiberglass cloth strip by brushing. After brushing evenly in one go, place it in a petri dish lined with a sample bag and prepare to put it into a forced-air drying oven.

[0065] Step 5: Before drying, preheat the oven to 85℃. Place the coated sample in the oven and observe the changes on the surface of the tape during the drying process. Avoid excessive drying time, which could cause cracking of the coating. The approximate drying time for one coat is 42 minutes. Apply three coats. The final thickness of the flame-retardant tape is approximately 0.6 mm, while maintaining good flexibility. The tape obtained in this embodiment has high flame retardancy (LOI=64.9%) and high mechanical strength (40.28 MPa).

[0066] A novel halogen-free cable wrapping material (i.e., a synergistic flame-retardant and reinforced cable wrapping material) is prepared by co-precipitation of magnesium carbonate trihydrate nanofibers and nanofloral clusters in a 1:1 mass ratio. The surface of the nanofibers and clusters is then modified using a silane coupling agent. The modified magnesium carbonate nanopowder is then mixed with attapulgite clay and EVA latex. Using a 90mm × 20mm fiberglass cloth as a substrate, the slurry is evenly coated onto both sides using a brushing method. After each coating, the material is dried in an 85℃ forced-air drying oven for approximately 42 minutes. To improve the coating thickness and performance, the coating is repeated three times, ultimately yielding a wrapping material with a thickness of approximately 0.6mm, exhibiting uniformity, density, good flexibility, and flame-retardant properties.

[0067] Application of a controllable preparation method for multimorphic nano-magnesium carbonate in synergistic flame-retardant-reinforced cable wrapping.

[0068] Application of a synergistic flame-retardant-reinforced cable wrap in power cables.

[0069] An electrical cable comprising the synergistic flame-retardant-enhanced cable wrapping of this embodiment. Example 4

[0070] A controllable preparation method for multimorphic nano-magnesium carbonate, comprising the following steps: Step 1: Magnesium sulfate heptahydrate is used as the magnesium source, and potassium carbonate is used as the precipitant, with a molar ratio of 3:1. The magnesium sulfate heptahydrate concentrations are 0.9 mol / L (nanofibers) and 0.4 mol / L (nanofibers), respectively. The reaction is carried out at 50°C for 40 minutes. (Before adding potassium carbonate, the magnesium source is first added with a mass equal to the Mg content of magnesium sulfate heptahydrate.) 2+ Tea saponin, which was completely converted to 3% of the theoretical mass of magnesium carbonate trihydrate, was used as a crystal form control agent. After the reaction, the solution was filtered through filter paper and repeatedly washed with deionized water to remove impurities. The washed sample was dried in a 90℃ forced-air drying oven for 3 hours to obtain magnesium carbonate trihydrate nanofibers and magnesium carbonate trihydrate nanofloral clusters, respectively.

[0071] Step two: The prepared magnesium carbonate trihydrate nanofibers (9g) and magnesium carbonate trihydrate nanoflora clusters (9g) were mixed at a mass ratio of 1:1, referred to as magnesium carbonate trihydrate FF, and added to 105mL of anhydrous ethanol, stirring until uniformly mixed. Then, 1% of the mass of magnesium carbonate trihydrate silane coupling agent was weighed and mixed with deionized water at a volume ratio of 1:2. After complete hydrolysis, this mixture was added to the above magnesium carbonate trihydrate / ethanol mixture. The mixture was then treated in an ultrasonic disperser for 10 minutes (100Hz, 50℃) to ensure thorough dispersion and surface reaction. After the reaction, the mixture was filtered, the solid product was collected, and dried in a forced-air drying oven at 80℃ for 2 hours to finally obtain the modified magnesium carbonate trihydrate mixed powder.

[0072] Step 3: Add 7.5g of attapulgite clay to a beaker and dissolve it in 70mL of deionized water. Place a rotor in the beaker and stir at 1300 rpm until the solution reaches a uniform viscous state. Then, add 4g of modified magnesium carbonate trihydrate FF mixed powder, remove the rotor, and stir with a glass rod for 15 minutes to ensure the mixture is thoroughly and evenly mixed. Finally, add 14g of EVA latex and continue stirring with a glass rod for 15 minutes until the adhesive is completely and evenly mixed to obtain the slurry.

[0073] Step 4: Cut a 90mm long and 20mm wide piece of fiberglass cloth as the base for the strap. Apply the slurry to both sides of the fiberglass cloth strip by brushing. After brushing evenly in one go, place it in a petri dish lined with a sample bag and prepare to put it into a forced-air drying oven.

[0074] Step 5: Before drying, preheat the oven to 80℃. Place the coated sample in the oven and observe the changes on the surface of the tape during the drying process. Avoid excessive drying time, which may cause the coating on the sample surface to crack. The drying time for one coat is approximately 40 minutes. Apply three coats. The final thickness of the flame-retardant tape is approximately 0.5mm, while maintaining good flexibility.

[0075] A novel halogen-free cable wrapping material (i.e., a synergistic flame-retardant and reinforced cable wrapping material) is prepared using a co-precipitation method to prepare the nano-sized magnesium carbonate nanofibers and nanofloral clusters in a 1:1 mass ratio as a flame-retardant material. The surface of the nano-sized magnesium carbonate nanofibers and clusters is then modified using a silane coupling agent. The modified magnesium carbonate nanopowder is then mixed with attapulgite clay and EVA latex is added. Using a 90mm × 20mm glass fiber cloth as a substrate, the slurry is uniformly coated onto both sides using a brushing method. After each coating, the material is dried in an 80℃ forced-air drying oven for approximately 40 minutes. To improve the coating thickness and performance, the coating is repeated three times, ultimately yielding a wrapping material with a thickness of approximately 0.5mm, exhibiting uniformity, density, good flexibility, and flame-retardant properties. The wrapping material obtained in this embodiment exhibits high flame retardancy (LOI = 63.9%) and high mechanical strength (40MPa).

[0076] Application of a controllable preparation method for multimorphic nano-magnesium carbonate in synergistic flame-retardant-reinforced cable wrapping.

[0077] Application of a synergistic flame-retardant-reinforced cable wrap in power cables.

[0078] An electrical cable comprising the synergistic flame-retardant-enhanced cable wrapping of this embodiment.

[0079] It should be understood that, in order to simplify this disclosure and aid in understanding one or more of the various aspects of the invention, features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof in the above description of exemplary embodiments of the invention. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed invention requires more features than expressly recited in each claim. Rather, as reflected in the claims, inventive aspects lie in fewer than all the features of the foregoingly disclosed embodiments. Therefore, the claims, following the detailed description, are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of the invention.

[0080] Although the invention has been described with reference to a limited number of embodiments, those skilled in the art will understand from the foregoing description that other embodiments are conceivable within the scope of the invention described herein. Furthermore, it should be noted that the language used in this specification has been chosen primarily for readability and instructional purposes, and not for the purpose of interpreting or limiting the subject matter of the invention. Therefore, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the invention is illustrative and not restrictive, and the scope of the invention is defined by the appended claims.

[0081] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A controllable preparation method for multi-morphological nano-magnesium carbonate, characterized in that, Includes the following steps: Step 1: Magnesium sulfate heptahydrate is used as the magnesium source, and potassium carbonate is used as the precipitant, with a molar ratio of 3:

1. The concentrations of magnesium sulfate heptahydrate are 0.8-1.2 mol / L and 0.1-0.5 mol / L, respectively. The reaction is carried out at 45-50℃ for 30-40 minutes. Before adding potassium carbonate, the magnesium source is first added with a mass equal to the Mg content of magnesium sulfate heptahydrate. 2+ Tea saponin, which was completely converted into 3% of the theoretical mass of magnesium carbonate trihydrate, was used as a crystal form control agent. After the reaction was completed, the mixture was washed and dried to obtain magnesium carbonate trihydrate nanofibers and magnesium carbonate trihydrate nanofloral clusters, respectively. Step 2: Mix 5-10g of prepared magnesium carbonate trihydrate nanofibers and 5-10g of magnesium carbonate trihydrate nanofloral clusters at a mass ratio of 1:1 (referred to as magnesium carbonate trihydrate), add to 100-120 mL of anhydrous ethanol, and stir until homogeneous to obtain a magnesium carbonate trihydrate / ethanol mixture. Then, weigh 1-2% of the mass of magnesium carbonate trihydrate silane coupling agent, mix the silane coupling agent with deionized water at a volume ratio of 1:2, and after complete hydrolysis, add it to the magnesium carbonate trihydrate / ethanol mixture to obtain a mixed system. Place the mixed system in an ultrasonic disperser for 10-15 minutes to ensure sufficient dispersion and surface reaction. After the reaction is complete, filter the mixture, collect the solid product, dry it, and finally obtain modified magnesium carbonate trihydrate mixed powder. Step 3: Add 6.5-9.5 g of attapulgite to a beaker and dissolve it in 50-80 mL of deionized water; place a rotor in the beaker and stir at 1000-1500 r / min until the solution becomes uniformly viscous; then add 3-6 g of modified magnesium carbonate trihydrate powder, remove the rotor, and stir with a glass rod for 15-30 minutes to ensure the mixture is thoroughly and evenly mixed; finally, add 10-14 g of EVA latex and continue stirring with a glass rod for 15-20 minutes until the adhesive is completely and evenly mixed to obtain a slurry; Step 4: Using fiberglass cloth as the substrate for the wrapping tape, apply the slurry to both sides of the fiberglass cloth by brushing. After brushing evenly in one go, place it in a petri dish lined with a sample bag and prepare to put it in the oven. Step 5: Before drying, turn on the oven to preheat, set the temperature to 80-90℃, place the coated sample in the oven, and dry for 40-45 minutes for each coating; after multiple coatings, the final thickness of the bag tape is 0.5-0.7mm.

2. The controllable preparation method according to claim 1, characterized in that, In step one, the washing and drying process is as follows: the solution is filtered through filter paper and repeatedly washed with deionized water to remove impurities. The washed sample is then dried in a forced-air drying oven at 80-90℃ for 2-3 hours.

3. The controllable preparation method according to claim 1, characterized in that, In step two, the ultrasonic power is 80-100Hz and the ultrasonic temperature is 50-60℃.

4. The controllable preparation method according to claim 1, characterized in that, In step two, the drying process is as follows: dry in a forced-air drying oven at 80-90℃ for 2-3 hours.

5. The controllable preparation method according to claim 1, characterized in that, In step four, the fiberglass cloth is 90mm long and 20mm wide.

6. The controllable preparation method according to claim 1, characterized in that, In steps four and five, the drying oven is a forced-air drying oven.

7. The application of the controllable preparation method according to any one of claims 1 to 6 in synergistic flame-retardant-reinforced cable wrapping.

8. The synergistic flame-retardant-reinforced cable wrapping prepared by the controllable preparation method according to any one of claims 1 to 6, characterized in that, The LOI of the strap is 63.9~65.1%, and the tensile strength is 40~41.44 MPa.

9. The application of the synergistic flame-retardant-reinforced cable wrapping according to claim 8 in power cables.

10. A power cable comprising the synergistic flame-retardant-reinforced cable wrapping of claim 8.

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