A flame-retardant and toughened cable material

Abstract

This application provides a flame-retardant and toughened cable material, prepared from the following components in parts by weight: 85-100 parts PVC resin, 15-20 parts dioctyl phthalate, 10-15 parts chlorinated paraffin, 10-15 parts dioctyl terephthalate, 40-50 parts heavy calcium carbonate, 5 parts stabilizer, 2-3 parts PE wax, 1-2 parts stearic acid, and 20-30 parts flame-retardant particles. The flame-retardant particles are composite microspheres formed by loading flame retardants onto nano-silica aerogel and grafting POSS onto its surface. Nano-silica aerogel has a higher temperature resistance limit, and its unique three-dimensional porous network structure can absorb heat and restrict oxygen diffusion. It can also load flame retardants, resulting in a more uniform distribution of the flame retardant. POSS acts as a bridge between the nano-silica aerogel and PVC resin, improving the compatibility and bonding strength between the flame-retardant particles and PVC resin, reducing stress concentration, and improving toughness, thus achieving simultaneous improvement in flame retardancy and toughness.

Description

Technical Field

[0001] This application belongs to the field of cable technology, and more specifically, relates to a flame-retardant and toughened cable material. Background Technology

[0002] Plastics used for the insulation and sheathing of wires and cables are commonly known as cable materials, which include various types such as rubber, plastics, and nylon. Almost all wire and cable products, except for bare wires such as steel-cored aluminum stranded wire and magnet wire, require an insulation layer. Currently, my country has numerous wire and cable manufacturers, creating a huge demand for wire and cable products; therefore, cable materials have a broad market prospect in my country.

[0003] Cable materials generally require good toughness, high tensile strength and elongation at break, and high flame retardant and fire-resistant properties. This ensures the structural integrity of the cable during laying or under stress and inhibits the spread of fire during high-temperature combustion. The flame-retardant properties of cable materials are typically achieved by adding flame retardants to the raw materials. However, the compatibility between flame retardants and polymer matrix materials is poor; excessive content can affect the continuity of the polymer matrix, creating stress concentration points, leading to increased material hardness and decreased toughness. Furthermore, the flame-retardant and fire-resistant properties of a single flame retardant used in conventional cable materials are not particularly excellent. Summary of the Invention

[0004] The purpose of this application is to provide a flame-retardant and toughened cable material to solve the technical problem in the prior art where the flame retardant and polymer matrix in the cable material have poor compatibility, resulting in reduced toughness.

[0005] To achieve the above objectives, the technical solution adopted in this application is: to provide a flame-retardant and toughened cable material, which is prepared by the following components in parts by weight:

[0006] 85-100 parts of PVC resin;

[0007] 15-20 parts of dioctyl phthalate;

[0008] 10-15 parts of chlorinated paraffin;

[0009] 10-15 parts of dioctyl terephthalate;

[0010] 40-50 servings of triple calcium supplement;

[0011] Stabilizer 5 parts;

[0012] 2-3 parts PE wax;

[0013] 1-2 parts stearic acid;

[0014] 20-30 parts flame retardant granules;

[0015] The flame-retardant particles are composite microspheres formed by loading flame retardants onto nano-silica aerogel and grafting POSS onto its surface.

[0016] In one embodiment, the method for preparing the flame-retardant particles includes the following steps:

[0017] Tetraethyl orthosilicate, water, ethanol, and acidic catalyst HCl are mixed and stirred to hydrolyze tetraethyl orthosilicate into silica sol, and silica sol is then converted into a three-dimensional network structure wet gel through a condensation reaction.

[0018] The flame retardant is pre-dispersed in a solvent, and then added at the initial stage of the condensation reaction of silicic acid, so that the flame retardant is embedded in the gel.

[0019] POSS was modified with epoxy groups, with each POSS molecule carrying multiple epoxy groups. POSS was then dispersed in an ethanol solution by ultrasonic stirring.

[0020] During the silica polycondensation stage, a POSS solution is added and a ring-opening reaction occurs, allowing the POSS to covalently connect to the Si-O-Si network.

[0021] The composite wet gel containing flame retardant and modified POSS is atomized into micron-sized composite microspheres by spray drying.

[0022] In one embodiment, the wet gel is pretreated using a supercritical drying process prior to spray drying to remove the solvent from the wet gel under supercritical liquid CO2 conditions.

[0023] In one embodiment, in the supercritical drying process, the pressurization process of liquid CO2 is divided into three stages, with pressures of 2 MPa, 5 MPa and 7.38 MPa in the three stages, and each stage is maintained for 10-15 minutes.

[0024] In one embodiment, the particle size of the prepared composite microspheres is 10-30 μm.

[0025] In one embodiment, the flame retardant is a composite flame retardant of ammonium polyphosphate and melamine cyanurate.

[0026] In one embodiment, the molar ratio of tetraethyl orthosilicate, water, and ethanol is 1:4:4, the concentration of the acidic catalyst HCl is 0.1-0.5 mol / L, the pH value is adjusted to 2-3, and the hydrolysis temperature is 25-40℃.

[0027] In one embodiment, the amount of flame retardant added to the obtained flame retardant particles is 10 wt%.

[0028] In one embodiment, the heavy calcium carbonate is active heavy calcium carbonate with a particle size of less than or equal to 5 μm.

[0029] The beneficial effects of the flame-retardant and toughened cable material provided in this application are as follows: Compared with the prior art, the flame-retardant and toughened cable material provided in this application uses PVC resin as the matrix and adopts composite microspheres formed by loading flame retardants onto nano-silica aerogel and grafting POSS onto the surface as flame-retardant particles. Compared with traditional single flame retardants such as inorganic flame retardants and phosphorus-based flame retardants, nano-silica aerogel has a higher temperature resistance limit and does not produce open flames or a molten state during combustion. The special three-dimensional porous network structure of the aerogel can also absorb heat and restrict oxygen diffusion, thus inhibiting combustion. The special three-dimensional porous network structure of nano-silica aerogel has a high specific surface area, which can better load flame retardants. On the one hand, it makes the flame retardant distribution more uniform, so that the flame retardant and nano-silica aerogel have synergistic heat insulation and flame retardant effects. On the other hand, nano-silica aerogel can also disperse and crosslink with POSS. In this way, POSS can act as a bridge between nano-silica aerogel and PVC resin, improving the compatibility and bonding force between flame-retardant particles and PVC resin, reducing stress concentration, and improving toughness. In addition, chlorinated paraffin and heavy calcium carbonate also have flame-retardant effects, working synergistically with flame-retardant particles for heat insulation and flame retardancy. Dioctyl phthalate, chlorinated paraffin, and dioctyl terephthalate, as toughening agents in the cable material, are present in a total of 35-50 parts. The proportion of plasticizer relative to the PVC resin is reasonable, resulting in a cable material with high toughness without being too soft. Furthermore, dioctyl terephthalate, as a specially added environmentally friendly component, reduces the amount of dioctyl phthalate and chlorinated paraffin used, thereby improving the environmental performance of the cable material to a certain extent. Compared to traditional cable materials, the flame-retardant toughening particles achieve simultaneous improvement in both flame-retardant and toughness properties. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application, 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 this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 A flowchart illustrating the preparation method of flame-retardant particles in the flame-retardant and toughened cable material provided in this application embodiment. Detailed Implementation

[0032] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0033] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0034] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0035] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0036] Please see Figure 1 The flame-retardant and toughened cable material provided in the embodiments of this application will now be described. The flame-retardant and toughened cable material is a PVC cable material that is prepared at 70°C, and is obtained from the following components in parts by weight:

[0037] 85-100 parts of PVC resin;

[0038] 15-20 parts of dioctyl phthalate;

[0039] 10-15 parts of chlorinated paraffin;

[0040] 10-15 parts of dioctyl terephthalate;

[0041] 40-50 servings of triple calcium supplement;

[0042] Stabilizer 5 parts;

[0043] 2-3 parts PE wax;

[0044] 1-2 parts stearic acid;

[0045] 20-30 parts flame retardant granules;

[0046] The flame-retardant particles are composite microspheres formed by loading flame retardants onto nano-silica aerogel and grafting POSS onto its surface.

[0047] Specifically, the flame-retardant and toughened cable material provided in this application uses PVC (Polyvinyl Chloride) resin as the matrix. PVC resin has a high volume resistivity (greater than 10 ohms). 14 With an excellent electrical insulation performance (Ωm), it can effectively isolate current leakage and ensure the safe operation of cables in high-voltage environments; polyvinyl chloride resin has good mechanical properties and toughness, meeting the requirements for cable bending and laying; it has excellent acid and alkali corrosion resistance, making it suitable for harsh environments such as chemical and marine environments; in addition, polyvinyl chloride resin has good melt flowability (melt index 1.5-3.0g / 10min), making it suitable for various molding processes such as extrusion and injection molding, resulting in high production efficiency.

[0048] Dioctyl phthalate (DOP), a primary plasticizer for PVC resin and a general-purpose plasticizer, reduces the viscosity of the PVC resin melt, enhancing the material's ductility, making cable materials easier to extrude and maintain a smooth surface. It significantly improves the flexibility and abrasion resistance of PVC resin. Furthermore, DOP exhibits excellent compatibility with PVC resin, is less prone to precipitation during high-temperature extrusion, ensuring the stability of continuous production and improving the processing performance of cable materials. In addition, the moderate polarity of DOP molecules allows for uniform dispersion in cable materials, reducing the risk of electrical breakdown and providing excellent voltage withstand performance.

[0049] Chlorinated paraffins are chlorinated derivatives of paraffin hydrocarbons, possessing low volatility, flame retardancy, and good electrical insulation properties. They are used as auxiliary plasticizers and flame retardants for PVC resins. Chlorinated paraffins contain 70% chlorine, which, while aiding in plasticization and improving the flexibility of cable materials, also enhances their flame retardant properties.

[0050] Dioctyl terephthalate (DTP) is a terephthalic acid ester compound with the carboxylic acid ester group of the benzene ring in the para-position (para-benzene structure). It is a low-toxicity, biodegradable petroleum compound and plasticizer synthesized through environmentally friendly processes. It is an environmentally friendly plasticizer with excellent heat resistance, electrical insulation, and environmental performance. The flame-retardant and toughened cable material provided in this application includes DTP, which reduces the amount of DTP and chlorinated paraffin used, thereby improving the environmental performance of the flame-retardant and toughened cable material.

[0051] Heavy calcium carbonate (CPC) is a white powder made from natural carbonate minerals (such as calcite, marble, and limestone) through mechanical crushing. Its chemical composition is CaCO3. It features high purity, high inertness, and good thermal stability (it does not decompose below 400℃). As an inorganic filler in the aforementioned flame-retardant and toughened cable material, it can improve the tensile strength and abrasion resistance of the cable material. Furthermore, inorganic fillers such as heavy calcium carbonate can also enhance the thermal insulation and flame-retardant properties of the flame-retardant and toughened cable material.

[0052] The stabilizers mainly consist of calcium and zinc salts, and are suitable for PVC resin-based cable materials. They are functional additives used to inhibit degradation and extend service life. Adding 3–6 parts of calcium-zinc stabilizer to PVC cable materials at 70–90℃ can also improve heat resistance and processing fluidity.

[0053] PE wax, also known as polyethylene wax, is a type of ultra-low molecular weight polyethylene. It has cold resistance, heat resistance, chemical corrosion resistance, and wear resistance, as well as excellent lubricity and dispersibility. It has high dispersibility for other fillers and fillers in cable materials, thereby improving the processing efficiency of cable materials and reducing material adhesion.

[0054] Stearic acid is a saturated long-chain fatty acid that can be used as a lubricant and release agent to improve the processing fluidity of cable materials and enhance the surface finish of finished cable materials.

[0055] The flame-retardant particles are composite microspheres formed by loading flame retardants onto nano-silica aerogel and grafting POSS onto its surface. The nano-silica aerogel has an ultra-low thermal conductivity, exhibiting excellent heat insulation and flame-retardant properties. It can significantly slow down heat transfer, preventing the spread of fire along cables. Furthermore, the nano-silica aerogel has a porous three-dimensional network structure, which can absorb heat and limit oxygen diffusion, inhibiting the combustion chain reaction and slowing flame propagation. Silica aerogel can be prepared using the sol-gel method. During the sol-gel process, a flame retardant is added, allowing it to embed within the gel. The flame retardant and nano-silica work synergistically to enhance the overall flame retardant effect of the particles. Furthermore, POSS can be added simultaneously during the sol-gel process. Specifically, POSS can be chemically grafted onto the surface of the silica aerogel through modification. When the flame retardant particles and the main polymer matrix of the cable material, namely PVC resin, are combined, POSS acts as a connecting bridge between the nano-silica aerogel and the PVC polymer, significantly improving the compatibility between the flame retardant particles and the PVC resin matrix. This results in a significant increase in the toughness, tensile strength, and elongation at break of the cable material.

[0056] The processing of the flame-retardant and toughened cable material is roughly as follows: First, prepare raw materials according to the above component ratio, accurately measure and mix each component raw material, and add the measured component raw materials to a high-speed mixer for preliminary mixing; after mixing, add the material to a cooling mixer or internal mixer for further deep mixing and plasticizing, with a plasticizing temperature of 165-170℃; after plasticizing, granulate the material through a granulator at a granulation temperature of 165-170℃ to obtain uniform PVC cable material granules.

[0057] In summary, the flame-retardant and toughened cable material provided in this application uses PVC resin as the matrix and employs composite microspheres formed by loading flame retardants onto nano-silica aerogel and grafting POSS onto its surface as flame-retardant particles. Compared to traditional single flame retardants such as inorganic flame retardants and phosphorus-based flame retardants, nano-silica aerogel has a higher temperature resistance limit and does not produce open flames or a molten state during combustion. The aerogel's unique three-dimensional porous network structure can also absorb heat and restrict oxygen diffusion, thus inhibiting combustion. The unique three-dimensional porous network structure of nano-silica aerogel has a high specific surface area, which can better load flame retardants. On the one hand, it makes the flame retardant distribution more uniform, allowing the flame retardant and nano-silica aerogel to synergistically provide heat insulation and flame retardancy. On the other hand, nano-silica aerogel can also disperse and crosslink with POSS, so POSS can act as a bridge between nano-silica aerogel and PVC resin, improving the compatibility and bonding force between flame-retardant particles and PVC resin, reducing stress concentration, and improving toughness. In addition, chlorinated paraffin and heavy calcium carbonate also have flame-retardant effects, working synergistically with flame-retardant particles for heat insulation and flame retardancy. Dioctyl phthalate, chlorinated paraffin, and dioctyl terephthalate, as toughening agents in the cable material, are present in a total of 35-50 parts. The proportion of plasticizer relative to the PVC resin is reasonable, resulting in a cable material with high toughness without being too soft. Furthermore, dioctyl terephthalate, as a specially added environmentally friendly component, reduces the amount of dioctyl phthalate and chlorinated paraffin used, thereby improving the environmental performance of the cable material to a certain extent. Compared to traditional cable materials, the flame-retardant toughening particles achieve simultaneous improvement in both flame-retardant and toughness properties.

[0058] In one embodiment, the method for preparing the flame-retardant particles includes the following steps:

[0059] Tetraethyl orthosilicate, water, ethanol, and acidic catalyst HCl are mixed and stirred to hydrolyze tetraethyl orthosilicate into silica sol, and silica sol is then converted into a three-dimensional network structure wet gel through a condensation reaction.

[0060] The flame retardant is pre-dispersed in a solvent, and then added at the initial stage of the condensation reaction of silicic acid, so that the flame retardant is embedded in the gel.

[0061] POSS was modified with epoxy groups, with each POSS molecule carrying multiple epoxy groups. POSS was then dispersed in an ethanol solution by ultrasonic stirring.

[0062] During the silica polycondensation stage, a POSS solution is added and a ring-opening reaction occurs, allowing the POSS to covalently connect to the Si-O-Si network.

[0063] The composite wet gel containing flame retardant and modified POSS is atomized into micron-sized composite microspheres by spray drying.

[0064] Specifically, nano-silica aerogels can be prepared using a sol-gel process, in which flame retardants and POSS are added to prepare composite microspheres. First, tetraethyl orthosilicate (TEO) is used as the silicon source, and ethanol as the co-solvent, which can both dissolve TCO and inhibit side reactions caused by excessive hydrolysis. Using HCl as an acidic catalyst, TCO undergoes hydrolysis with water under the action of the acidic catalyst to produce silicic acid and ethanol. Silicic acid forms silicon-oxygen bonds through dehydration condensation, initially generating linear or slightly branched silicic acid oligomers. These silicic acid oligomers further condense to form a wet gel with a three-dimensional network structure.

[0065] Phosphorus-based flame retardants, such as ammonium polyphosphate, can be used. Phosphorus-based flame retardants and silica gel solutions have similar polarities, providing compatibility. The flame retardant is pre-dissolved in water or ethanol, and then added at the initial stage of the silicic acid condensation reaction. This allows the flame retardant to embed itself within the gel through hydrogen bonding or physical dispersion, rather than simply adsorbing onto the gel surface. This reduces the probability of flame retardant detachment during subsequent drying and also improves the dispersibility of the flame retardant within the gel. Using water or ethanol as the solvent for the flame retardant, and since silica gel solutions also contain water and ethanol as solvents, using the same solvent during the addition of the flame retardant ensures good compatibility and reduces unnecessary side reactions.

[0066] Before grafting POSS into a silica gel solution, POSS needs to be modified and pretreated. Generally, POSS is epoxy-modified, and then the modified POSS is dispersed in an ethanol solution using ultrasonic stirring to optimize dispersibility and viscosity. This reduces agglomeration after the silica gel solution is added, thus improving the grafting effect.

[0067] Next, POSS is added to a silica gel solution for grafting. The POSS solution needs to be added during the condensation reaction of silicic acid. The epoxy groups on the POSS surface have high reactivity and can open rings under acidic conditions to form covalent bonds with nucleophilic groups such as hydroxyl groups. For example, ≡Si-OH + epoxy group (POSS) → ≡Si-OC-(POSS) + H2O, allowing POSS to be covalently embedded in the Si-O-Si network. Each POSS molecule carries multiple epoxy groups, which can react simultaneously with multiple silicic acid oligomer segments to form crosslinking points. Unreacted silicic acid hydroxyl groups continue to dehydrate and condense, expanding the network structure and ultimately forming a three-dimensional Si-O-Si network with POSS as the rigid core.

[0068] Finally, the composite wet gel containing flame retardant and modified POSS was atomized into micron-sized composite microspheres via spray drying. During spray drying, a centrifugal atomizer was used with an atomization pressure of 0.2-0.6 MPa, a gas flow rate of 50-100 L / h, a feed rate of 5-15 mL / min, an inlet temperature of 120-180℃, and an outlet temperature of 60-90℃. During atomization, the wet gel forms fine droplets through the atomizer. The solvent on the droplet surface evaporates rapidly, and the internal gel network begins to shrink. Then, the droplets are rapidly dehydrated in the high-temperature gas flow, and the flame retardant and POSS are locked within the gel skeleton, forming a porous microsphere structure. The Si-O-Si network of POSS enhances the rigidity of the microsphere skeleton and reduces structural collapse during drying; while the flame retardant (such as APP) forms a phosphate carbon layer inside the microsphere, improving flame retardant efficiency. At an atomization pressure of 0.2-0.6 MPa, the size of the atomized droplets can be controlled, generating microspheres of 10-30 μm. The inlet temperature is set to 120-180℃ to quickly evaporate the solvent and prevent excessive shrinkage or aggregation of the gel; the outlet temperature is set to 60-90℃ to avoid the decomposition of the flame retardant or the destruction of the POSS structure due to high temperature.

[0069] The 10-30μm composite microspheres obtained by the above process have a small particle size, which allows them to be better dispersed in PVC resin. During the sol-gel process, flame retardants are added and embedded in the colloid. POSS is modified and grafted into the nano-silica aerogel. The porous structure of nano-silica with a high specific surface area allows both flame retardants and POSS to be more evenly distributed. Moreover, POSS enables the flame retardant particles to be better dispersed and cross-linked with PVC resin, thereby improving both the flame retardancy and toughness of the cable material.

[0070] In one embodiment, the wet gel is pretreated using a supercritical drying process before spray drying. Under supercritical conditions of liquid CO2, the gel is transformed into a fluid, eliminating gas-liquid surface tension and removing the solvent. This allows the wet gel to be dispersed into micron-sized droplets via an atomizer, followed by rapid solvent evaporation in a high-temperature gas stream, forming solid microspheres. This process eliminates gas-liquid interfacial tension, prevents gel network collapse, and preserves the porous network structure of the silica aerogel, as well as the uniform distribution of POSS and flame retardants. In a supercritical CO2 environment, POSS grafting can enhance the compressive strength of the microspheres (by 20–50%), reduce structural deformation, and compensate for porosity loss during subsequent spray drying.

[0071] The supercritical drying process operates at a temperature of 31.1℃ and a pressure of 7.38 MPa. In the supercritical state, carbon dioxide loses its gas-liquid interface, and surface tension completely disappears, avoiding the shrinkage or collapse of the gel skeleton caused by capillary forces in traditional drying, thus preserving the material's three-dimensional porous structure. The relatively low critical pressure of carbon dioxide (7.38 MPa) is easily achievable in existing industrial equipment, reducing the extreme requirements for high-pressure vessels. The high diffusivity and low viscosity of supercritical fluids allow for rapid penetration into the gel pores, significantly shortening drying time and improving efficiency by more than 50% compared to atmospheric pressure drying. The critical temperature of 31.1℃ is close to room temperature, achieving the supercritical state without high-temperature heating. The low temperature (31.1℃) avoids high-temperature pyrolysis or oxidation reactions, making it particularly suitable for composite systems containing POSS-grafted materials, resulting in energy savings.

[0072] In one embodiment, the supercritical drying process involves three stages of pressurizing liquid CO2, with pressures of 2 MPa, 5 MPa, and 7.38 MPa respectively, each maintained for 10-15 minutes. This gradient pressurization method avoids stress rupture of the gel network caused by sudden pressure increases, reduces pore collapse rate, and increases the specific surface area of ​​the aerogel.

[0073] In one embodiment, the resulting composite microspheres have a particle size of 10-30 μm. This 10-30 μm particle size range ensures uniform dispersion of the composite microspheres within the PVC resin matrix, reducing agglomeration and thus improving the uniformity of flame retardant distribution (such as ammonium polyphosphate) and extending the flame retardant action time. Furthermore, composite microspheres within this particle size range provide mechanical support (such as increased compressive strength) in cable materials without increasing matrix brittleness due to excessively large particle sizes, thus balancing the material's flexibility and mechanical strength.

[0074] In one embodiment, the flame retardant is a composite flame retardant of ammonium polyphosphate and melamine cyanurate. Ammonium polyphosphate decomposes at high temperatures to release polyphosphoric acid, catalyzing the formation of a dense silicate char layer on the aerogel surface, isolating heat and oxygen transfer while inhibiting the escape of combustible gases. Meanwhile, melamine cyanurate decomposes to produce nitrogen-containing inert gases (such as NH3 and H2O), diluting the concentration of oxygen and combustible gases, delaying the combustion chain reaction, and promoting char layer expansion. The two complement each other in the silica aerogel, synergistically increasing the limiting oxygen index (LOI) by 20-30%, representing a dual flame retardant mechanism of "char layer + gas phase flame retardancy" for intumescent flame retardants, thus improving flame retardant performance. The decomposition temperature of melamine cyanurate (≥250℃) matches that of ammonium polyphosphate (≥300℃), synergistically enhancing the structural stability of the aerogel at high temperatures. Furthermore, the composite flame retardant system has minimal impact on the density of the nano-silica aerogel, resulting in significantly better overall performance than a single flame retardant.

[0075] In one embodiment, during the preparation of nano-silica aerogels via a sol-gel process, the molar ratio of tetraethyl orthosilicate, water, and ethanol is 1:4:4. This ratio provides a high water content, promoting the decomposition of tetraethyl orthosilicate into monomers. The ethanol solvent ratio (C2H5OH / TEOS = 4) dilutes the reactant concentration, preventing excessively rapid condensation reactions that could lead to localized aggregation, thus facilitating the formation of a uniform three-dimensional network framework. Furthermore, this ratio provides a suitable sol viscosity, ensuring the formation of a porous structure during the aging process of the wet gel, resulting in nano-silica aerogels with a high specific surface area. Additionally, the concentration of the acidic catalyst HCl is 0.1-0.5 mol / L, and the pH is adjusted to 2-3. Under an acidic environment (pH 2-3), H… + This process catalyzes the hydrolysis of tetraethyl orthosilicate to generate silicic acid monomers, while simultaneously inhibiting premature condensation reactions. This avoids excessively short gelation times or localized dense structures. The catalytic activity is moderate, with a match between hydrolysis and condensation rates, reducing stress concentration within the gel and lowering the risk of cracking during subsequent drying. The hydrolysis temperature for the sol-gel process is 25-40℃. The low temperature slows the reaction rate, preventing excessive exothermic reactions that could lead to localized overheating or phase separation in the sol, thus improving the continuity of the gel network. No high-temperature conditions are required, making it suitable for industrial production. This process optimizes the nanoporous structure and mechanical stability of nano-silica aerogels.

[0076] In one embodiment, the flame retardant added to the obtained flame retardant particles is 10 wt%. That is, the amount of flame retardant added is 10% of the total mass of the flame retardant, POSS, and nano-silica aerogel contained in the flame retardant particles. If the amount of flame retardant added is too low, the flame retardant effect will be reduced; if the amount of flame retardant added is higher than 10 wt%, the flame retardant is likely to clog the pores of the nano-silica aerogel, which will also reduce the flame retardant effect.

[0077] In one embodiment, the heavy calcium carbonate is active heavy calcium carbonate with a particle size of less than or equal to 5 μm. Using active calcium carbonate with a small particle size can improve the decrease in mechanical properties caused by agglomeration.

[0078] Example 1

[0079] A flame-retardant and toughened cable material is prepared by the following components in parts by weight:

[0080] 90 parts of PVC resin;

[0081] 18 parts of dioctyl phthalate;

[0082] 12 parts of chlorinated paraffin;

[0083] 12 parts of dioctyl terephthalate;

[0084] 45 portions of triple calcium;

[0085] Stabilizer 5 parts;

[0086] 2 parts PE wax;

[0087] 1 part stearic acid;

[0088] 25 parts flame retardant granules;

[0089] The preparation process of flame-retardant particles is as follows:

[0090] Tetraethyl orthosilicate, water, ethanol, and acidic catalyst HCl were mixed and stirred. The molar ratio of tetraethyl orthosilicate, water, and ethanol was 1:4:4, the concentration of acidic catalyst HCl was 0.3 mol / L, and the pH was adjusted to 2.5. This caused tetraethyl orthosilicate to hydrolyze to form silicic acid sol at a hydrolysis temperature of 28°C. The silicic acid then underwent a condensation reaction to form a wet gel with a three-dimensional network structure.

[0091] The flame retardant is pre-dispersed in a solvent, and then added at the initial stage of the polycondensation reaction of silicic acid, so that the flame retardant is embedded in the gel. The flame retardant is a composite flame retardant of ammonium polyphosphate and melamine cyanurate.

[0092] POSS was modified with epoxy groups and then dispersed in an ethanol solution by ultrasonic stirring.

[0093] During the silica polycondensation stage, a POSS solution is added and a ring-opening reaction occurs, allowing the POSS to covalently connect to the Si-O-Si network.

[0094] The wet gel was pretreated using a supercritical drying process. The solvent in the wet gel was removed under supercritical liquid CO2 conditions. The pressurization process of the liquid CO2 was divided into three stages, with pressures of 2 MPa, 5 MPa and 7.38 MPa in the three stages, and each stage was maintained for 10-15 minutes.

[0095] The composite wet gel containing flame retardant and modified POSS was atomized into micron-sized composite microspheres by spray drying, and the average particle size of the obtained composite microspheres was 25 μm.

[0096] According to the component ratio of Example 1 above, raw materials are prepared, each component is accurately measured and mixed, and the measured component raw materials are added to a high-speed mixer for preliminary mixing; the mixed material is added to an internal mixer for further deep mixing and plasticization, and the plasticization temperature is 165-170℃; the plasticized material is granulated by a granulator at a granulation temperature of 165-170℃ to obtain uniform PVC cable material granules.

[0097] Example 2

[0098] A flame-retardant and toughened cable material is prepared by the following components in parts by weight:

[0099] 98 parts of PVC resin;

[0100] 15 parts of dioctyl phthalate;

[0101] 10 parts of chlorinated paraffin;

[0102] 10 parts of dioctyl terephthalate;

[0103] 50 servings of triple calcium carbonate;

[0104] Stabilizer 5 parts;

[0105] 3 parts PE wax;

[0106] Stearic acid 2 parts;

[0107] 30 parts flame-retardant granules;

[0108] The preparation process of flame-retardant particles is as follows:

[0109] Tetraethyl orthosilicate, water, ethanol, and acidic catalyst HCl were mixed and stirred. The molar ratio of tetraethyl orthosilicate, water, and ethanol was 1:4:4, the concentration of acidic catalyst HCl was 0.5 mol / L, and the pH was adjusted to 2. This caused tetraethyl orthosilicate to hydrolyze to form silicic acid sol. The hydrolysis temperature was 25℃, and the silicic acid then underwent a condensation reaction to form a wet gel with a three-dimensional network structure.

[0110] The flame retardant is pre-dispersed in a solvent, and then added at the initial stage of the polycondensation reaction of silicic acid, so that the flame retardant is embedded in the gel. The flame retardant is a composite flame retardant of ammonium polyphosphate and melamine cyanurate.

[0111] POSS was modified with epoxy groups and then dispersed in an ethanol solution by ultrasonic stirring.

[0112] During the silica polycondensation stage, a POSS solution is added and a ring-opening reaction occurs, allowing the POSS to covalently connect to the Si-O-Si network.

[0113] The wet gel was pretreated using a supercritical drying process. The solvent in the wet gel was removed under supercritical liquid CO2 conditions. The pressurization process of the liquid CO2 was divided into three stages, with pressures of 2 MPa, 5 MPa and 7.38 MPa in the three stages, and each stage was maintained for 10-15 minutes.

[0114] The composite wet gel containing flame retardant and modified POSS was atomized into micron-sized composite microspheres by spray drying, and the average particle size of the obtained composite microspheres was 15 μm.

[0115] According to the component ratio of Example 2 above, raw materials are prepared, each component raw material is accurately measured and mixed, and the measured component raw materials are added to a high-speed mixer for preliminary mixing; the mixed material is added to an internal mixer for further deep mixing and plasticization, and the plasticization temperature is 165-170℃; the plasticized material is granulated by a granulator, and the granulation temperature is also 165-170℃ to obtain uniform PVC cable material granules.

[0116] Example 3

[0117] A flame-retardant and toughened cable material is prepared by the following components in parts by weight:

[0118] 85 parts of PVC resin;

[0119] 20 parts of dioctyl phthalate;

[0120] 15 parts of chlorinated paraffin;

[0121] 15 parts of dioctyl terephthalate;

[0122] 40 servings of triple calcium;

[0123] Stabilizer 5 parts;

[0124] 2 parts PE wax;

[0125] 1 part stearic acid;

[0126] 20 parts flame retardant granules;

[0127] The preparation process of flame-retardant particles is as follows:

[0128] Tetraethyl orthosilicate, water, ethanol, and acidic catalyst HCl were mixed and stirred. The molar ratio of tetraethyl orthosilicate, water, and ethanol was 1:4:4, the concentration of acidic catalyst HCl was 0.1 mol / L, and the pH was adjusted to 2. This caused tetraethyl orthosilicate to hydrolyze to form silicic acid sol. The hydrolysis temperature was 40℃, and the silicic acid then underwent a condensation reaction to form a wet gel with a three-dimensional network structure.

[0129] The flame retardant is pre-dispersed in a solvent, and then added at the initial stage of the polycondensation reaction of silicic acid, so that the flame retardant is embedded in the gel. The flame retardant is a composite flame retardant of ammonium polyphosphate and melamine cyanurate.

[0130] POSS was modified with epoxy groups and then dispersed in an ethanol solution by ultrasonic stirring.

[0131] During the silica polycondensation stage, a POSS solution is added and a ring-opening reaction occurs, allowing the POSS to covalently connect to the Si-O-Si network.

[0132] The wet gel was pretreated using a supercritical drying process. The solvent in the wet gel was removed under supercritical liquid CO2 conditions. The pressurization process of the liquid CO2 was divided into three stages, with pressures of 2 MPa, 5 MPa and 7.38 MPa in the three stages, and each stage was maintained for 10-15 minutes.

[0133] The composite wet gel containing flame retardant and modified POSS was atomized into micron-sized composite microspheres by spray drying, and the average particle size of the obtained composite microspheres was 10 μm.

[0134] According to the component ratio of Example 3 above, raw materials are prepared, each component raw material is accurately measured and mixed, and the measured component raw materials are added to a high-speed mixer for preliminary mixing; the mixed material is added to an internal mixer for further deep mixing and plasticization, and the plasticization temperature is 165-170℃; the plasticized material is granulated by a granulator, and the granulation temperature is also 165-170℃ to obtain uniform PVC cable material granules.

[0135] The performance test data of the cable materials prepared in Examples 1, 2, and 3 are shown in Table 1:

[0136] Table 1 Performance test data of cable material

[0137]

[0138] In summary, the flame-retardant and toughened cable material provided in this application has good voltage resistance, insulation performance, high tensile strength and elongation at break, good toughness, and also has the advantages of being environmentally friendly and flame-retardant, making it suitable for use as an insulating sheath for wires and cables.

[0139] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A flame-retardant and toughened cable material, characterized in that, It is prepared from the following components in parts by mass: 85-100 parts of PVC resin; 15-20 parts of dioctyl phthalate; 10-15 parts of chlorinated paraffin; 10-15 parts of dioctyl terephthalate; 40-50 servings of triple calcium supplement; Stabilizer 5 parts; 2-3 parts PE wax; 1-2 parts stearic acid; 20-30 parts flame retardant granules; The flame-retardant particles are composite microspheres formed by loading flame retardants onto nano-silica aerogel and grafting POSS onto its surface. The preparation method of the flame-retardant particles includes the following steps: Tetraethyl orthosilicate, water, ethanol, and acidic catalyst HCl are mixed and stirred to hydrolyze tetraethyl orthosilicate into silica sol, and silica sol is then converted into a three-dimensional network structure wet gel through a condensation reaction. The flame retardant is pre-dispersed in a solvent, and then added at the initial stage of the condensation reaction of silicic acid, so that the flame retardant is embedded in the gel. POSS was modified with epoxy groups, with each POSS molecule carrying multiple epoxy groups. POSS was then dispersed in an ethanol solution by ultrasonic stirring. During the silica polycondensation stage, a POSS solution is added and a ring-opening reaction occurs, allowing the POSS to covalently connect to the Si-O-Si network. The composite wet gel containing flame retardant and modified POSS is atomized into micron-sized composite microspheres by spray drying. Before spray drying, the wet gel is pretreated using a supercritical drying process to remove the solvent from the wet gel under supercritical liquid CO2 conditions. In the supercritical drying process, the pressurization process of liquid CO2 is divided into three stages, with pressures of 2 MPa, 5 MPa and 7.38 MPa in sequence, and each stage is maintained for 10-15 minutes.

2. The flame-retardant and toughened cable material as described in claim 1, characterized in that, The particle size of the prepared composite microspheres is 10-30 μm.

3. The flame-retardant and toughened cable material as described in claim 1, characterized in that, The flame retardant is a composite flame retardant of ammonium polyphosphate and melamine cyanurate.

4. The flame-retardant and toughened cable material as described in claim 1, characterized in that, The molar ratio of tetraethyl orthosilicate, water, and ethanol is 1:4:4, the concentration of the acidic catalyst HCl is 0.1-0.5 mol / L, the pH value is adjusted to 2-3, and the hydrolysis temperature is 25-40℃.

5. The flame-retardant and toughened cable material according to any one of claims 1-4, characterized in that, The flame retardant added to the obtained flame retardant granules is 10 wt%.

6. The flame-retardant and toughened cable material according to any one of claims 1-4, characterized in that, The heavy calcium carbonate is an active heavy calcium carbonate with a particle size of less than or equal to 5 μm.

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