High-temperature-resistant high-flame-retardant polyurethane cable material and preparation process thereof

Abstract

The invention discloses a high-temperature-resistant high-flame-retardant polyurethane cable material and a preparation process thereof, and relates to the technical field of cable sheaths and insulating materials. The cable material comprises thermoplastic polyurethane, organosilicon modified polyurethane containing boric acid ester bonds, a microencapsulated phosphorus-nitrogen-silicon synergistic flame retardant, a graphene oxide / fluorophlogopite hybrid filler and other auxiliaries. By introducing the dynamic borate bond, the core-shell packaged flame retardant and the hybrid reinforcing filler, all the components generate a synergistic effect, the problem that flame retardance, heat resistance and mechanical properties of a traditional material are difficult to consider is effectively solved, good processing performance is kept, meanwhile, excellent flame retardance, high temperature resistance, toughness and long-term thermal stability are achieved, and the flame-retardant and heat-resistant composite material is suitable for large-scale popularization and application. And the cable is suitable for cable sheaths and insulating layers with harsh performance requirements.

Description

Technical Field

[0001] This invention relates to the field of cable sheathing and insulation materials, specifically to a high-temperature resistant and high-flame-retardant polyurethane cable material and its preparation process. Background Technology

[0002] Thermoplastic polyurethane elastomers are widely used as outer sheath materials for cables, especially flexible cables such as charging pile cables and robot cables, due to their excellent flexibility, abrasion resistance, oil resistance, and good mechanical properties. However, unmodified thermoplastic polyurethane has a low oxygen index, making it a flammable material. Furthermore, it produces molten droplets and releases toxic fumes during combustion, severely limiting its application in environments with stringent safety requirements. Therefore, flame-retardant modification of thermoplastic polyurethane to prepare halogen-free flame-retardant polyurethane cable materials that combine good mechanical properties, processability, and high flame-retardant ratings has become an important research direction in the field of cable materials.

[0003] Currently, the main approach to improving the flame retardant properties of polyurethane is to add flame retardants. Common halogen-free flame retardant systems include phosphorus-based flame retardants (such as ammonium polyphosphate and hypophosphite), nitrogen-based flame retardants (such as melamine and its derivatives), inorganic hydroxides (such as magnesium hydroxide and aluminum hydroxide), and silicon-based flame retardants (such as silicone resins and silsesquioxanes). To overcome the limitations of single flame retardants, researchers often use a combination of multiple flame retardants, utilizing the synergistic effects between elements such as phosphorus-nitrogen and phosphorus-silicon to improve flame retardant efficiency. For example, ammonium polyphosphate is combined with melamine as an intumescent flame retardant system, or inorganic fillers modified with silane coupling agents are used to improve dispersibility.

[0004] Despite some progress in existing technologies, numerous challenges remain. First, the addition of large amounts of flame-retardant fillers often leads to a significant decrease in the mechanical properties of the polyurethane matrix, particularly its flexibility and elongation at break. Second, small-molecule flame retardants are prone to migration and precipitation during processing or use, affecting not only flame retardant durability but also potentially damaging the material's appearance and electrical properties. Furthermore, many flame retardants exhibit poor interfacial compatibility with the polyurethane matrix, easily inducing stress concentration points and reducing the material's fatigue and torsional resistance. In addition, achieving high flame retardant ratings (such as UL94 V-0) typically requires high amounts of flame retardant, which further deteriorates the material's processing flowability and the surface quality of the final product. While some solutions aiming to improve performance through chemical modification or the construction of complex cross-linked networks may improve certain properties, they often come at the cost of sacrificing the material's reprocessability or making processes more complex and sensitive.

[0005] Therefore, developing a new type of polyurethane cable material that can achieve efficient, durable, and stable halogen-free flame retardancy without significantly compromising its inherent excellent mechanical and processing properties, and that also possesses good high-temperature resistance and resistance to complex mechanical stress, is of great practical significance for meeting the stringent requirements of high-end cables, especially charging pile cables in dynamic operating environments. Summary of the Invention

[0006] The purpose of this invention is to provide a high-temperature resistant and high-flame-retardant polyurethane cable material and its preparation process, so as to solve the problems mentioned in the background art.

[0007] In a first aspect, the present invention provides a high-temperature resistant and high-flame-retardant polyurethane cable material, comprising the following raw materials in parts by weight: 60-90 parts of thermoplastic polyurethane; 10-25 parts of organosilicon-modified polyurethane containing borate ester bonds; 15-30 parts of microencapsulated phosphorus-nitrogen-silicon synergistic flame retardant; 5-15 parts of graphene oxide / fluorophlogopite hybrid filler; 3-8 parts of aluminum diethylphosphonate synergist; Antioxidant 1010: 0.3-1 part; Antioxidant 168, 0.3-1 part; 0.5-1.5 parts of calcium stearate; UV absorber UV-531 0.5-2 parts.

[0008] As a preferred embodiment of the present invention, the method for preparing the organosilicon-modified polyurethane containing boron ester bonds is as follows: Polytetrahydrofurandiol, α,ω-dihydroxypolydimethylsiloxane, 1,4-butanediol, and dibutyltin dilaurate were added to a dry reactor and stirred and dehydrated at 80°C under nitrogen protection for 30 min. The temperature was then lowered to 60°C, and isophorone diisocyanate was added. The reaction was carried out at 80°C for 2 h to obtain isocyanate-terminated polyurethane prepolymer. The system was then cooled to 50°C, and 2-hydroxyphenylboronic acid was added. The reaction was continued for 1.5 h. The product was poured into a polytetrafluoroethylene mold and cured at 100°C for 6 h. After cooling, the product was crushed and granulated to obtain the final product. The molecular weight of the polytetrahydrofuran diol is 2000; The molecular weight of the polydimethylsiloxane is 1000; The mass ratio of polytetrahydrofuran diol, α,ω-dihydroxypolydimethylsiloxane, 1,4-butanediol, dibutyltin dilaurate, isophorone diisocyanate, and 2-hydroxyphenylboronic acid is 100:15:5:0.1:45:8.

[0009] It should be noted that by introducing polysiloxane segments as soft segments into the polyurethane backbone and utilizing the reaction of the hydroxyl groups of 2-hydroxyphenylboronic acid with the terminal isocyanate groups of the prepolymer, phenylboronic acid structural units are incorporated into the polymer side chains. During subsequent curing or application, the boric acid groups on the side chains can undergo reversible dehydration condensation with the hydroxyl groups in the system to form dynamic borate bonds. This structure enables the material to exhibit thermoplastic elastomer characteristics at room temperature, while under stress or thermal action, the reversible breakage and recombination of the dynamic borate bonds can effectively dissipate energy, endowing the material with certain damping properties and potential self-healing capabilities. When applied to cable materials, the silicone segments help improve the heat resistance and flexibility of the matrix, while the dynamic cross-linked network can preferentially rearrange at high temperatures in the early stages of a fire, relieving internal stress and preventing sheath cracking. Its decomposition products and the dynamic network structure help promote the formation of a continuous and dense char layer at high temperatures.

[0010] As a preferred embodiment of the present invention, the preparation method of the microencapsulated phosphorus-nitrogen-silicon synergistic flame retardant is as follows: Melamine cyanurate and aluminum hypophosphite were mixed evenly in a high-speed mixer to obtain a mixed powder. The mixed powder was dispersed in a mixed solvent. Vinyltrimethoxysilane and tetraethyl orthosilicate were added, and the pH was adjusted to 9-10 with ammonia. The mixture was stirred at 45°C for 4 hours, filtered, washed with ethanol, and dried under vacuum at 80°C for 12 hours to obtain the final product. The mixed solvent is an ethanol / water mixed solution with a volume ratio of 1:1. The mass ratio of melamine cyanurate, aluminum hypophosphite, mixed solvent, vinyltrimethoxysilane, and tetraethyl orthosilicate is 70:30:300:10:5.

[0011] It should be noted that the microencapsulated phosphorus-nitrogen-silicon synergistic flame retardant uses a compound of melamine cyanurate and aluminum hypophosphite as its core. This core is formed by the co-hydrolysis and condensation of vinyltrimethoxysilane and tetraethyl orthosilicate in an alkaline ethanol / water system, coating the surface with a polysiloxane / silica hybrid shell. The microencapsulation structure encapsulates the gas source (cyanurate) and acid source (aluminum hypophosphite), forming the core of the intumescent flame retardant system. The thermally stable silicon-based shell improves the hydrophobicity and dispersibility of the flame retardant in the polymer matrix. When the cable material is heated, the shell delays the premature decomposition and migration of the flame-retardant components in the core. When the temperature continues to rise until the shell softens or cracks, the phosphorus-nitrogen components in the core are rapidly released, exerting flame-retardant and smoke-suppressing effects in both the gas and condensed phases. Simultaneously, the decomposition products of the silicon-based shell participate in the formation of a thermally insulating and insulating silicate ceramic layer, achieving spatiotemporal synergistic flame retardancy of phosphorus, nitrogen, and silicon elements.

[0012] As a preferred embodiment of the present invention, the preparation method of the graphene oxide / fluorophlogopite hybrid filler is as follows: Expandable graphite was added to concentrated sulfuric acid and stirred in an ice bath. Hydrogen peroxide solution was slowly added to obtain a mixture. Fluorophyllite powder was added to the mixture, and the temperature was raised to 40°C and stirred for 4 hours. After the reaction was completed, the mixture was diluted, filtered, and washed until neutral. The filter cake was redispersed in deionized water, and the pH was adjusted to 4-5 with acetic acid. γ-(2,3-epoxypropyl)propyltrimethoxysilane was added, and the mixture was refluxed at 70°C for 6 hours. After the reaction was completed, the mixture was filtered, washed with deionized water and ethanol until neutral, dried under vacuum at 60°C for 24 hours, and then gently ground to obtain the final product. The fluorophlogopite powder has a flake diameter of 10-50 μm; The concentration of the concentrated sulfuric acid is 98%; The concentration of the hydrogen peroxide solution is 30%; The mass ratio of expandable graphite, fluorophlogopite powder, concentrated sulfuric acid, hydrogen peroxide solution, and γ-(2,3-epoxypropyl)propyltrimethoxysilane is 5:5:50:10:2.

[0013] It should be noted that the expansionable graphite is partially oxidized and intercalated through treatment with strong acid and oxidants to generate graphene oxide. This process may also cause some etching and hydroxylation of the fluorophlogopite surface. The epoxy groups of the silane coupling agent KH-560 react with the oxygen-containing functional groups on the graphene oxide, and its methoxy groups hydrolyze and condense with the silanol groups on the mica surface, covalently linking the graphene oxide and mica sheets to form a hybrid lamellar structure with high-modulus mica as the framework and graphene oxide anchored to the surface. At room temperature, this filler, due to the high aspect ratio and rigidity of the mica sheets, mainly acts as a reinforcing phase, improving the mechanical strength and dimensional stability of the cable material. When the ambient temperature reaches the thermal expansion temperature of graphene oxide, the intercalated material between the graphene layers decomposes thermally, generating gas and causing a dramatic volume expansion. However, this expansion process is restricted and guided by the covalently bonded rigid mica sheets, thus transforming into a huge expansion stress perpendicular to the lamellar plane. When the cable sheath is exposed to fire, this directional expansion force can actively act on the forming, loose initial carbon layer, apply radial expansion stress to it, and force viscous degradation products to fill the space between them, physically reconstructing an expanded carbon layer with higher strength and more closed-cell structure, significantly improving the integrity of the thermal insulation barrier.

[0014] A second aspect of the present invention provides a preparation process for a high-temperature resistant and high-flame-retardant polyurethane cable material, specifically including the following steps: S1. Weigh the raw materials according to the stated weight proportions, place them in a high-speed mixer, and mix them at a speed of 800-1200 r / min for 5-8 minutes at room temperature to obtain a premix. S2. The premixed material is fed into the hopper of a co-rotating twin-screw extruder, and after melt blending, extrusion, water cooling, and traction, strip-shaped material is obtained. The temperature settings for each section of the twin-screw extruder from the feed inlet to the die head are as follows: Zone 1 150-155℃, Zone 2 165-170℃, Zone 3 175-180℃, Zone 4 180-185℃, Zone 5 175-180℃, and Die head 170-175℃. The screw speed of the twin-screw extruder is 200-300 r / min; S3. The strip-shaped material obtained in step S2 is fed into a pelletizer for granulation, and then dried by blowing at 70-80℃ for 4-6 hours to obtain the high temperature resistant and high flame retardant polyurethane cable material.

[0015] It is important to note that when the borate ester bond-containing silicone-modified polyurethane exists alone, it primarily functions as a toughening and heat-resistant modifier for the matrix, alleviating processing and usage stresses through dynamic bonding. When the microencapsulated phosphorus-nitrogen-silicon synergistic flame retardant exists alone, it serves as the main flame-retardant component, achieving high-efficiency flame retardancy through core-shell controlled release and multi-element synergy. When the graphene oxide / fluorophlogopite hybrid filler exists alone, it acts as a reinforcing and thermally conductive filler, undergoing physical expansion at high temperatures.

[0016] When borate-containing silicone-modified polyurethane works in conjunction with microencapsulated phosphorus-nitrogen-silicon synergistic flame retardants, the viscoelastic precursor formed by the borate-containing silicone-modified polyurethane at high temperature provides a good dispersion and reaction carrier for the active flame retardant components released by the microencapsulated phosphorus-nitrogen-silicon synergistic flame retardants, which helps to form a denser and more adhesive expanded char layer. The two exhibit chemical synergy in the condensed phase char formation process.

[0017] When organosilicon-modified polyurethane containing borate ester bonds works together with graphene oxide / fluorophlogopite hybrid filler, under high-temperature fire conditions, the directional expansion stress generated by the graphene oxide / fluorophlogopite hybrid filler and the viscoelasticity provided by the dynamic network rearrangement of organosilicon-modified polyurethane containing borate ester bonds combine to create a carbon layer that is physically expanded while gaining better plastic deformation capacity. This results in a carbon layer with both high expansion ratio and good structural stability, which is a synergy between mechanical behavior and material rheology.

[0018] When microencapsulated phosphorus-nitrogen-silicon synergistic flame retardants work together with graphene oxide / fluorophlogopite hybrid fillers, the porous framework structure formed by the high-temperature expansion of the graphene oxide / fluorophlogopite hybrid fillers provides a physical space for the dispersion and bonding of gaseous flame-retardant substances and molten silicates generated by the decomposition of the microencapsulated phosphorus-nitrogen-silicon synergistic flame retardants. The flame-retardant substances, combined with the expanded carbon body, ultimately form a ceramic-carbon composite shielding layer with effectively dispersed phosphorus-nitrogen-silicon elements and optimized microstructure within the carbon layer.

[0019] Compared with the prior art, the present invention has the following beneficial effects: This invention constructs a multi-mechanism synergistic material system by introducing three functional components: organosilicon-modified polyurethane with borate ester bonds, microencapsulated phosphorus-nitrogen-silicon synergistic flame retardant, and graphene oxide / fluorophlogopite hybrid filler. This system not only balances the mechanical strength, flexibility, and heat resistance required for cable materials but also enhances the flame retardancy rating and fire safety performance through multiple mechanisms, including chemical flame retardancy, physical expansion enhancement, and dynamic network energy dissipation. The synergistic effects among the functional components exceed their individual effects, resulting in a denser and more stable protective layer structure with more prominent thermal insulation and barrier properties. The microencapsulation technology employed in this invention improves the interfacial compatibility and durability of the flame retardant, while the design of the dynamically covalently modified PU and hybrid filler alleviates, to some extent, the problems of material embrittlement or processing difficulties caused by traditional flame retardant additives, contributing to the acquisition of high-performance cable sheath materials with more balanced overall performance. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Preparation Example 1 The preparation method of organosilicon-modified polyurethane containing borate ester bonds is as follows: 100g of polytetrahydrofuran diol, 15g of α,ω-dihydroxypolydimethylsiloxane, 5g of 1,4-butanediol, and 0.1g of dibutyltin dilaurate were added to a dry reactor and stirred and dehydrated at 80℃ under nitrogen protection for 30 min. The temperature was then lowered to 60℃, and 45g of isophorone diisocyanate was added. The reaction was carried out at 80℃ for 2 h to obtain isocyanate-terminated polyurethane prepolymer. The system was then cooled to 50℃, and 8g of 2-hydroxyphenylboronic acid was added. The reaction was continued for 1.5 h, and the product was poured into a polytetrafluoroethylene mold and cured at 100℃ for 6 h. After cooling, the product was crushed and granulated to obtain the final product.

[0022] Preparation Example 2 The preparation method of microencapsulated phosphorus-nitrogen-silicon synergistic flame retardant is as follows: 70g of melamine cyanurate and 30g of aluminum hypophosphite were mixed evenly in a high-speed mixer to obtain a mixed powder. The mixed powder was dispersed in a mixed solvent of 300g of ethanol and water in a volume ratio of 1:1. 10g of vinyltrimethoxysilane and 5g of tetraethyl orthosilicate were added, and the pH was adjusted to 9-10 with ammonia. The mixture was stirred at 45°C for 4 hours, filtered, washed with ethanol, and dried under vacuum at 80°C for 12 hours to obtain the final product. Preparation Example 3 The preparation method of graphene oxide / fluorophlogopite hybrid filler is as follows: Add 5g of expandable graphite to 50g of 98% concentrated sulfuric acid, stir under ice bath, and slowly add 10g of 30% hydrogen peroxide solution to obtain a mixture. Add 5g of fluorophlogopite powder to the mixture, heat to 40℃ and stir for 4h. After the reaction, dilute, filter, and wash until neutral. Redisperse the filter cake in deionized water, adjust the pH to 4.5 with acetic acid, add 2g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and reflux at 70℃ for 6h. After the reaction, filter, wash with deionized water and ethanol until neutral, dry under vacuum at 60℃ for 24h, and gently grind to obtain the final product.

[0023] Example 1 A preparation process for a high-temperature resistant and high-flame-retardant polyurethane cable material specifically includes the following steps: S1. Weigh out 75 parts by weight of thermoplastic polyurethane, 17.5 parts by weight of silicone-modified polyurethane containing borate ester bonds, 22.5 parts by weight of microencapsulated phosphorus-nitrogen-silicon synergistic flame retardant, 10 parts by weight of graphene oxide / fluorophlogopite hybrid filler, 5.5 parts by weight of aluminum diethylphosphinate synergist, 0.65 parts by weight of antioxidant 1010, 0.65 parts by weight of antioxidant 168, 1 part by weight of calcium stearate and 1.3 parts by weight of ultraviolet absorber UV-531, place them in a high-speed mixer and mix at 1000 r / min for 6 min at room temperature to obtain a premix. S2. The premixed material is fed into the hopper of a co-rotating twin-screw extruder. The temperature of each section of the twin-screw extruder from the feed inlet to the die head is set as follows: Zone 1 155℃, Zone 2 165℃, Zone 3 175℃, Zone 4 185℃, Zone 5 180℃, and the die head 170℃. The screw speed of the twin-screw extruder is 250 r / min. After melt blending, extrusion, water cooling, and traction, strip-shaped material is obtained. S3. The strip-shaped material obtained in step S2 is fed into a pelletizer for granulation, and then dried at 75°C for 5 hours to obtain the high-temperature resistant and high-flame-retardant polyurethane cable material.

[0024] In this embodiment, some of the raw materials used are the same as those obtained in Preparation Examples 1-3, and the other examples are the same.

[0025] Example 2 A preparation process for a high-temperature resistant and high-flame-retardant polyurethane cable material specifically includes the following steps: S1. Weigh out 60 parts by weight of thermoplastic polyurethane, 10 parts by weight of silicone-modified polyurethane containing borate ester bonds, 15 parts by weight of microencapsulated phosphorus-nitrogen-silicon synergistic flame retardant, 5 parts by weight of graphene oxide / fluorophlogopite hybrid filler, 3 parts by weight of aluminum diethylphosphinate synergist, 0.3 parts by weight of antioxidant 1010, 0.3 parts by weight of antioxidant 168, 0.5 parts by weight of calcium stearate and 0.5 parts by weight of ultraviolet absorber UV-531, place them in a high-speed mixer, and mix at 1000 r / min for 6 min at room temperature to obtain a premix. S2. The premixed material is fed into the hopper of a co-rotating twin-screw extruder. The temperature of each section of the twin-screw extruder from the feed inlet to the die head is set as follows: Zone 1 155℃, Zone 2 165℃, Zone 3 175℃, Zone 4 185℃, Zone 5 180℃, and the die head 170℃. The screw speed of the twin-screw extruder is 250 r / min. After melt blending, extrusion, water cooling, and traction, strip-shaped material is obtained. S3. The strip-shaped material obtained in step S2 is fed into a pelletizer for granulation, and then dried at 75°C for 5 hours to obtain the high-temperature resistant and high-flame-retardant polyurethane cable material.

[0026] Example 3 A preparation process for a high-temperature resistant and high-flame-retardant polyurethane cable material specifically includes the following steps: S1. Weigh out 90 parts by weight of thermoplastic polyurethane, 25 parts by weight of silicone-modified polyurethane containing borate ester bonds, 30 parts by weight of microencapsulated phosphorus-nitrogen-silicon synergistic flame retardant, 15 parts by weight of graphene oxide / fluorophlogopite hybrid filler, 8 parts by weight of aluminum diethylphosphinate synergist, 1 part by weight of antioxidant 1010, 1 part by weight of antioxidant 168, 1.5 parts by weight of calcium stearate and 2 parts by weight of ultraviolet absorber UV-531, place them in a high-speed mixer, and mix at 1000 r / min for 6 min at room temperature to obtain a premix. S2. The premixed material is fed into the hopper of a co-rotating twin-screw extruder. The temperature of each section of the twin-screw extruder from the feed inlet to the die head is set as follows: Zone 1 155℃, Zone 2 165℃, Zone 3 175℃, Zone 4 185℃, Zone 5 180℃, and the die head 170℃. The screw speed of the twin-screw extruder is 250 r / min. After melt blending, extrusion, water cooling, and traction, strip-shaped material is obtained. S3. The strip-shaped material obtained in step S2 is fed into a pelletizer for granulation, and then dried at 75°C for 5 hours to obtain the high-temperature resistant and high-flame-retardant polyurethane cable material.

[0027] Comparative Example 1 The difference between this comparative example and Example 1 is that the organosilicon-modified polyurethane containing borate ester bonds prepared in Example 1 was not added; instead, an equal part by weight of commercially available hydroxyl-terminated polydimethylsiloxane-modified polyurethane elastomer was added.

[0028] The commercially available hydroxyl-terminated polydimethylsiloxane-modified polyurethane elastomer was purchased from Xi'an Qiyue Biotechnology Co., Ltd., with product number Q-0015090.

[0029] Comparative Example 2 The difference between this comparative example and Example 1 is that the microencapsulated phosphorus-nitrogen-silicon synergistic flame retardant prepared in Example 2 was not added. Instead, an equal weight of a flame retardant made by a simple physical mixture of melamine cyanurate and aluminum hypophosphite in a mass ratio of 7:3 was added.

[0030] Comparative Example 3 The difference between this comparative example and Example 1 is that the graphene oxide / fluorophlogopite hybrid filler prepared in Example 3 was not added. Instead, an equal weight of filler consisting of a simple physical mixture of expandable graphite and fluorophlogopite powder in a mass ratio of 1:1 was added.

[0031] test: I. Limiting Oxygen Index The determination was conducted in accordance with GB / T 2406.2-2009 Determination of Combustion Behavior by Oxygen Index Method for Plastics - Part 2: Room Temperature Test.

[0032] II. Vertical Combustion Rating According to GB / T 2408-2021 "Determination of flammability of plastics - Horizontal and Vertical Methods", the UL94 vertical burning method was used for the determination.

[0033] III. Heat distortion temperature According to GB / T 1634.2-2019 Determination of temperature of deformation under load for plastics - Part 2: Plastics and hard rubber, the temperature was determined under a bending stress of 1.8 MPa.

[0034] IV. Tensile Properties According to GB / T 1040.2-2006 Determination of tensile properties of plastics - Part 2: Test conditions for molded and extruded plastics, tensile strength and elongation at break were determined.

[0035] V. Impact Strength According to GB / T 1843-2008 "Determination of Impact Strength of Plastic Cantilever Beams", the impact strength of cantilever beams with notches was determined.

[0036] VI. Performance retention rate after thermal aging The samples were placed in a 135℃ forced-air oven for 168 hours of hot air aging, according to GB / T 7141-2008 "Test Method for Thermal Aging of Plastics". The changes in tensile strength and impact strength before and after aging were tested. The calculation formula is as follows: Tensile strength retention rate = (Tensile strength after aging / Tensile strength before aging) × 100%; Impact strength retention rate = Impact strength after aging / Impact strength before aging × 100%.

[0037] VII. Summary of Results Table 1

[0038] VII. Discussion of Results As shown in Table 1, the high-temperature resistant and high-flame-retardant polyurethane cable materials prepared in Examples 1-3 of the present invention have excellent comprehensive performance, including high flame retardancy, high heat resistance, good mechanical properties and excellent long-term thermal stability.

[0039] Compared to Examples 1-3, Comparative Example 1 showed a significant decrease in heat distortion temperature, impact strength, and performance retention rate after thermal aging. This indicates that the organosilicon-modified polyurethane containing borate ester bonds, through its dynamically reversible borate ester bonds, effectively improves the material's heat resistance, impact toughness, and long-term thermal stability while imparting good processability and flexibility.

[0040] Compared to Examples 1-3, Comparative Example 2 exhibited the lowest limiting oxygen index. This indicates that microencapsulation not only delays the decomposition and migration of the flame retardant through the siloxane shell, thereby improving flame retardant efficiency, but its surface properties may also improve compatibility with the matrix, thus achieving a high flame retardant rating while minimizing negative impacts on the material's mechanical properties.

[0041] Compared to Examples 1-3, Comparative Example 3 exhibited the worst overall performance, with significantly lower flame retardancy, mechanical properties, and heat resistance compared to the examples. This indicates that the synergistic structure formed by the chemical bonding of the graphene oxide / fluorophlogopite hybrid filler can more effectively construct a three-dimensional reinforcement and barrier network within the matrix, thereby simultaneously improving material performance in multiple dimensions such as flame retardancy, reinforcement, and heat resistance, far exceeding the capabilities of simple physical mixing.

[0042] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0043] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the scope defined by the invention, and all such modifications and additions should fall within the protection scope of the present invention.

Claims

1. A high-temperature resistant and high-flame-retardant polyurethane cable material, characterized in that: Including the following parts by weight of raw materials: 60-90 parts of thermoplastic polyurethane; 10-25 parts of organosilicon-modified polyurethane containing borate ester bonds; 15-30 parts of microencapsulated phosphorus-nitrogen-silicon synergistic flame retardant; 5-15 parts of graphene oxide / fluorophlogopite hybrid filler; 3-8 parts of aluminum diethylphosphonate synergist; Antioxidant 1010: 0.3-1 part; Antioxidant 168, 0.3-1 part; 0.5-1.5 parts of calcium stearate; UV absorber UV-531 0.5-2 parts.

2. The high-temperature resistant and high-flame-retardant polyurethane cable material according to claim 1, characterized in that: The preparation method of the organosilicon-modified polyurethane containing borate ester bonds is as follows: Polytetrahydrofuran diol, α,ω-dihydroxypolydimethylsiloxane, 1,4-butanediol, and dibutyltin dilaurate were added to a dry reactor and stirred and dehydrated at 80°C under nitrogen protection for 30 min. The temperature was then lowered to 60°C, and isophorone diisocyanate was added. The reaction was carried out at 80°C for 2 h to obtain isocyanate-terminated polyurethane prepolymer. The system was then cooled to 50°C, and 2-hydroxyphenylboronic acid was added. The reaction was continued for 1.5 h. The product was then poured into a polytetrafluoroethylene mold and cured at 100°C for 6 h. After cooling, the product was crushed and granulated to obtain the final product.

3. The high-temperature resistant and high-flame-retardant polyurethane cable material according to claim 2, characterized in that: The molecular weight of the polytetrahydrofurandiol is 2000; the molecular weight of the polydimethylsiloxane is 1000; and the mass ratio of the polytetrahydrofurandiol, α,ω-dihydroxypolydimethylsiloxane, 1,4-butanediol, dibutyltin dilaurate, isophorone diisocyanate, and 2-hydroxyphenylboronic acid is 100:15:5:0.1:45:

8.

4. The high-temperature resistant and high-flame-retardant polyurethane cable material according to claim 1, characterized in that: The preparation method of the microencapsulated phosphorus-nitrogen-silicon synergistic flame retardant is as follows: Melamine cyanurate and aluminum hypophosphite were mixed evenly in a high-speed mixer to obtain a mixed powder. The mixed powder was dispersed in a mixed solvent. Vinyltrimethoxysilane and tetraethyl orthosilicate were added, and the pH was adjusted to 9-10 with ammonia. The mixture was stirred at 45°C for 4 hours, filtered, washed with ethanol, and dried under vacuum at 80°C for 12 hours to obtain the final product.

5. The high-temperature resistant and high-flame-retardant polyurethane cable material according to claim 4, characterized in that: The mixed solvent is an ethanol / water mixed solution with a volume ratio of 1:1; the mass ratio of melamine cyanurate, aluminum hypophosphite, mixed solvent, vinyltrimethoxysilane and tetraethyl orthosilicate is 70:30:300:10:

5.

6. The high-temperature resistant and high-flame-retardant polyurethane cable material according to claim 1, characterized in that: The preparation method of the graphene oxide / fluorophlogopite hybrid filler is as follows: Expandable graphite was added to concentrated sulfuric acid and stirred in an ice bath. Hydrogen peroxide solution was slowly added to obtain a mixture. Fluorophyllite powder was added to the mixture, and the temperature was raised to 40°C and stirred for 4 hours. After the reaction was completed, the mixture was diluted, filtered, and washed until neutral. The filter cake was redispersed in deionized water, and the pH was adjusted to 4-5 with acetic acid. γ-(2,3-epoxypropoxy)propyltrimethoxysilane was added, and the mixture was refluxed at 70°C for 6 hours. After the reaction was completed, the mixture was filtered, washed with deionized water and ethanol until neutral, and dried under vacuum at 60°C for 24 hours. After gentle grinding, the final product was obtained.

7. The high-temperature resistant and high-flame-retardant polyurethane cable material according to claim 6, characterized in that: The fluorophlogopite powder has a flake diameter of 10-50 μm; the concentrated sulfuric acid has a concentration of 98%; the hydrogen peroxide solution has a concentration of 30%; and the mass ratio of expandable graphite, fluorophlogopite powder, concentrated sulfuric acid, hydrogen peroxide solution, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane is 5:5:50:10:

2.

8. A preparation process for a high-temperature resistant and high-flame-retardant polyurethane cable material as described in any one of claims 1-7, characterized in that: Specifically, the following steps are included: S1. Weigh the raw materials according to the stated weight proportions, place them in a high-speed mixer, and mix them at a speed of 800-1200 r / min for 5-8 minutes at room temperature to obtain a premix. S2. The premixed material is fed into the hopper of a co-rotating twin-screw extruder, and after melt blending, extrusion, water cooling, and traction, strip-shaped material is obtained. S3. The strip-shaped material obtained in step S2 is fed into a pelletizer for granulation, and then dried by blowing at 70-80℃ for 4-6 hours to obtain the high temperature resistant and high flame retardant polyurethane cable material.

9. The preparation process of a high-temperature resistant and high-flame-retardant polyurethane cable material according to claim 8, characterized in that: In step S2, the temperature of each section of the twin-screw extruder from the feed inlet to the die head is set as follows: Zone 1 150-155℃, Zone 2 165-170℃, Zone 3 175-180℃, Zone 4 180-185℃, Zone 5 175-180℃, and the die head 170-175℃.

10. The preparation process of a high-temperature resistant and high-flame-retardant polyurethane cable material according to claim 8, characterized in that: In step S2, the screw speed of the twin-screw extruder is 200-300 r / min.

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