Flexible carbonized flame-retardant thermal insulation material and preparation method and application thereof

Abstract

The application provides a flexible carbonized flame-retardant thermal insulation material and a preparation method and application thereof, and belongs to the technical field of composite materials; a polyurethane main chain is formed by the reaction of polytetrahydrofuran and isophorone diisocyanate, and 2,2'-dithiodiethanol is introduced to construct a dynamic crosslinking structure, so that the material is endowed with flexibility, self-repairing property and carbonization capacity, and the cell stability and flame-retardant property are simultaneously enhanced; a graft copolymer containing an amide bond is generated by the reaction of polycaprolactone diol and N-(2-aminoethyl) ethanolamine, a hydrogen bond network is formed, and the toughness, tear strength and flame-retardant thermal insulation property are improved; phenol-terminated isocyanate is reacted with polyethylene glycol to form an in-situ crosslinking plasticizer, self-reaction is avoided, and the flexibility, processability and carbonization denseness are improved; in combination with the action of an antimony trioxide auxiliary agent and the like, the cell structure is stabilized, the mechanical property, thermal stability and flame-retardant effect are improved, and the composite material is endowed with excellent comprehensive performance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of composite materials, and relates to a flexible carbonized flame-retardant thermal insulation material as well as a preparation method and application thereof. BACKGROUND

[0002] In order to cope with fire accidents, the demand for flame-retardant materials is increasingly urgent. Flame-retardant fabrics, as a kind of key protective materials, are widely used in firefighting clothes, work clothes, military equipment, aerospace suits and other applications that need to resist flames and high temperatures. These fabrics not only have to withstand extreme heat and flames, but also need to maintain a certain degree of comfort and flexibility while ensuring the safety of the users.

[0003] Traditional flame-retardant materials have deficiencies in fireproof performance, which may fail to effectively prevent the spread of flames when a fire occurs, or release toxic gases during combustion, affecting the health and safety of the users.

[0004] In addition, existing flame-retardant materials may become brittle or lose elasticity after long-term use or high-temperature exposure, leading to a decline in structural performance and affecting the overall protective effect. SUMMARY

[0005] In view of the above problems, the present application aims to provide a flexible carbonized flame-retardant thermal insulation material as well as a preparation method and application thereof. In this application, polytetrahydrofuran is reacted with isophorone diisocyanate to form a polyurethane backbone, and 2,2'-dithiodiethanol is introduced to build a dynamic cross-linking structure, giving the material flexibility, self-repairing property and carbonization ability, while enhancing the stability of the foam and the flame-retardant performance. A graft copolymer containing amide bonds is formed by the reaction of polycaprolactone diol and N-(2-aminoethyl) ethanolamine, forming a hydrogen bond network to improve the toughness, tear strength and flame-retardant thermal insulation performance. Phenol-terminated isocyanate is reacted with polyethylene glycol to form an in-situ cross-linking plasticizer, avoiding self-reaction and improving flexibility, processing performance and carbonization density. With the action of antimony trioxide and other additives, the foam structure is stabilized, and the mechanical properties, thermal stability and flame-retardant effect are improved.

[0006] To achieve this purpose, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a preparation method of a flexible carbonized flame-retardant thermal insulation material, which comprises:

[0008] S1: polytetrahydrofuran 2000 and isophorone diisocyanate are added to tetrahydrofuran to obtain reaction liquid A, and after reaction, 2,2'-dithiodiethanol and 1,4-diazabicyclo[2.2.2]octane are added to obtain reaction liquid B, and the reaction is continued, and the dynamic cross-linking prepolymer is obtained after post-treatment;

[0009] S2: Polycaprolactone diol and N-(2-aminoethyl)ethanolamine are placed in a molten reaction vessel and reacted under a nitrogen atmosphere to obtain a pretreated product, which is then post-treated to obtain a hydrogen-bonded toughened graft copolymer.

[0010] S3: Hexamethylene diisocyanate and phenol are melt-mixed and reacted to obtain phenol-terminated isocyanate; it is then mixed with polyethylene glycol to obtain reaction solution C, reacted, and post-treated to obtain an in-situ crosslinking plasticizer.

[0011] S4: Polyvinyl chloride, in-situ crosslinking plasticizer, and dioctyl phthalate are added to a mixer and mixed until homogeneous. Polyurethane and dynamic crosslinking prepolymer are added and mixed until homogeneous. Finally, nitrile rubber, hydrogen-bonded toughening graft copolymer, silica, stearic acid, zinc oxide, and antimony trioxide are added to obtain a preliminary mixture. After preliminary mixing, the mixture is mixed at a second speed to obtain a mitered compound. After cooling, it is placed in an open mill, and AC foaming agent and urea are added and mixed. Sulfur and accelerator are added and mixed until homogeneous. The mixture is then slit to obtain mixed slices, which are placed on a flat vulcanizing machine and pressed. After depressurization and foaming, flexible carbonized flame-retardant thermal insulation material is obtained.

[0012] Specifically, S1: Polytetrahydrofuran 2000 and isophorone diisocyanate were added to tetrahydrofuran, and dibutyltin dilaurate was added to obtain reaction solution A. After the reaction, 2,2ʹ-dithiodiethanol and 1,4-diazabicyclo[2.2.2]octane were added to obtain reaction solution B. The reaction was continued, and the product was obtained by vacuum distillation and drying to obtain the dynamic crosslinked prepolymer.

[0013] S2: Polycaprolactone diol and N-(2-aminoethyl)ethanolamine are placed in a molten reaction vessel, preheated under a nitrogen atmosphere, and reacted to obtain a pretreated product. After cooling, the product is washed, dried, pulverized, and sieved to obtain a hydrogen-bonded toughened graft copolymer.

[0014] S3: Hexamethylene diisocyanate and phenol are melt-mixed, and dibutyltin dilaurate is added. After reaction, vacuum distillation and treatment are carried out to obtain phenol-terminated isocyanate. It is then mixed with polyethylene glycol to obtain reaction solution C. After reaction, vacuum distillation and treatment are carried out to obtain an in-situ crosslinking plasticizer.

[0015] S4: Polyvinyl chloride, in-situ crosslinking plasticizer, and dioctyl phthalate are added to a mixer and mixed at the first speed until homogeneous. Polyurethane and dynamic crosslinking prepolymer are added and mixed evenly. Finally, nitrile rubber, hydrogen-bonded toughening graft copolymer, silica, stearic acid, zinc oxide, and antimony trioxide are added to obtain a preliminary mixture. After preliminary mixing, the mixture is mixed at the second speed to obtain a mitered compound. After cooling, it is placed in a two-roll mill, and AC foaming agent and urea are added and mixed. Sulfur and accelerator are added and mixed until homogeneous. The mixture is then slit to obtain mixed slices, which are placed on a flat vulcanizing machine and pressed. After depressurization and foaming, flexible carbonized flame-retardant thermal insulation material is obtained.

[0016] As a preferred technical solution of the present invention, in step S1, the mass ratio of polytetrahydrofuran 2000 to isophorone diisocyanate is 1:(0.2-0.25), for example, it can be 1:0.2, 1:0.205, 1:0.21, 1:0.215, 1:0.22, 1:0.225, 1:0.23, 1:0.235, 1:0.24, 1:0.245 or 1:0.25, but it is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0017] In some optional embodiments, the amount of dibutyltin dilaurate is 0.2-0.4% of the total mass of polytetrahydrofuran 2000 and isophorone diisocyanate, for example, it can be 0.2%, 0.22%, 0.24%, 0.26%, 0.28%, 0.3%, 0.32%, 0.34%, 0.36%, 0.38% or 0.4%, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0018] In some alternative embodiments, the reaction temperature of the reaction solution A is 50-60°C, for example, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C or 60°C, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0019] In some alternative embodiments, the reaction time of the reaction solution A is 1-2 hours, for example, it can be 1 hour, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours or 2 hours, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0020] In some optional embodiments, the amount of 2,2ʹ-dithiodiethanol fed is 8-12% of the total mass of polytetrahydrofuran 2000 and isophorone diisocyanate, for example, it can be 8%, 8.4%, 8.8%, 9.2%, 9.6%, 10%, 10.4%, 10.8%, 11.2%, 11.6% or 12%, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0021] In some alternative embodiments, the amount of 1,4-diazabicyclo[2.2.2]octane fed is 0.4-0.5% of the total mass of polytetrahydrofuran 2000 and 2,2ʹ-dithiodiethanol, for example, it can be 0.4%, 0.41%, 0.42%, 0.43%, 0.44%, 0.45%, 0.46%, 0.47%, 0.48%, 0.49% or 0.5%, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0022] In some alternative embodiments, the reaction temperature of the reaction solution B is 70-80°C, for example, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C or 80°C, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0023] In some alternative embodiments, the reaction time of the reaction solution B is 2-3 hours, for example, 2 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3 hours, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0024] As a preferred technical solution of the present invention, in step S2, the mass ratio of the polycaprolactone diol to N-(2-aminoethyl)ethanolamine is (3-4):1, for example, it can be 3:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1, 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1 or 4:1, but it is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0025] In some optional embodiments, the preheating temperature of the polycaprolactone diol and N-(2-aminoethyl)ethanolamine in the molten reaction vessel is 50-60°C, for example, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C or 60°C, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0026] In some optional embodiments, the preheating time of the polycaprolactone diol and N-(2-aminoethyl)ethanolamine in the molten reactor is 30-60 min, for example, 30 min, 33 min, 36 min, 39 min, 42 min, 45 min, 48 min, 51 min, 54 min, 57 min or 60 min, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0027] In some optional embodiments, the reaction temperature of the polycaprolactone diol and N-(2-aminoethyl)ethanolamine in the molten reactor is 160-180°C, for example, 160°C, 162°C, 164°C, 166°C, 168°C, 170°C, 172°C, 174°C, 176°C, 178°C or 180°C, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0028] In some optional embodiments, the reaction time of the polycaprolactone diol and N-(2-aminoethyl)ethanolamine in the molten reactor is 5-6 h, for example, 5 h, 5.1 h, 5.2 h, 5.3 h, 5.4 h, 5.5 h, 5.6 h, 5.7 h, 5.8 h, 5.9 h or 6 h, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0029] As a preferred technical solution of the present invention, in step S3, the molar ratio of the hexamethylene diisocyanate and phenol melt-mixed is 1:(1-1.2), for example, it can be 1:1, 1:1.02, 1:1.04, 1:1.06, 1:1.08, 1:1.1, 1:1.12, 1:1.14, 1:1.16, 1:1.18 or 1:1.2, but it is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0030] In some alternative embodiments, the reaction temperature of the hexamethylene diisocyanate with phenol is 100-110°C, for example, 100°C, 101°C, 102°C, 103°C, 104°C, 105°C, 106°C, 107°C, 108°C, 109°C or 110°C, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0031] In some alternative embodiments, the reaction time of the hexamethylene diisocyanate with phenol is 6-8 hours, for example, 6 hours, 6.2 hours, 6.4 hours, 6.6 hours, 6.8 hours, 7 hours, 7.2 hours, 7.4 hours, 7.6 hours, 7.8 hours or 8 hours, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0032] In some alternative embodiments, the molar ratio of the phenol-terminated isocyanate to polyethylene glycol is 1:(1-1.2), for example, it can be 1:1, 1:1.02, 1:1.04, 1:1.06, 1:1.08, 1:1.1, 1:1.12, 1:1.14, 1:1.16, 1:1.18 or 1:1.2, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0033] In some optional embodiments, the reaction temperature of the reaction solution C is 140-150°C, for example, it can be 140°C, 141°C, 142°C, 143°C, 144°C, 145°C, 146°C, 147°C, 148°C, 149°C or 150°C, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0034] In some alternative embodiments, the reaction time of the reaction solution C is 2-3 hours, for example, 2 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3 hours, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0035] As a preferred technical solution of the present invention, in step S4, the mixing temperature of the internal mixer is 150-155℃, for example, it can be 150℃, 150.5℃, 151℃, 151.5℃, 152℃, 152.5℃, 153℃, 153.5℃, 154℃, 154.5℃ or 155℃, but it is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0036] In some alternative embodiments, the first mixing speed of the internal mixer is 60-80 rpm, for example, it can be 60 rpm, 62 rpm, 64 rpm, 66 rpm, 68 rpm, 70 rpm, 72 rpm, 74 rpm, 76 rpm, 78 rpm or 80 rpm, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0037] In some alternative embodiments, the initial mixture is initially mixed for 1-2 minutes, for example, 1 minute, 1.1 minutes, 1.2 minutes, 1.3 minutes, 1.4 minutes, 1.5 minutes, 1.6 minutes, 1.7 minutes, 1.8 minutes, 1.9 minutes or 2 minutes, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0038] In some alternative embodiments, the second rotational speed is 140-150 rpm, for example, it can be 140 rpm, 141 rpm, 142 rpm, 143 rpm, 144 rpm, 145 rpm, 146 rpm, 147 rpm, 148 rpm, 149 rpm or 150 rpm, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0039] In some alternative embodiments, the initial mixture is kneaded at a second rotation speed for 5-10 minutes, for example, 5 minutes, 5.5 minutes, 6 minutes, 6.5 minutes, 7 minutes, 7.5 minutes, 8 minutes, 8.5 minutes, 9 minutes, 9.5 minutes, or 10 minutes, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0040] In some alternative embodiments, the temperature at which the mixed chips are placed on a flat vulcanizing machine and pressurized is 150-160°C, for example, 150°C, 151°C, 152°C, 153°C, 154°C, 155°C, 156°C, 157°C, 158°C, 159°C or 160°C, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0041] In some alternative embodiments, the mixed chips are placed in a flat vulcanizing machine and pressurized to 8-10 MPa, for example, 8 MPa, 8.2 MPa, 8.4 MPa, 8.6 MPa, 8.8 MPa, 9 MPa, 9.2 MPa, 9.4 MPa, 9.6 MPa, 9.8 MPa or 10 MPa, but are not limited to such values, and values ​​not mentioned in this range are also applicable.

[0042] In some alternative embodiments, the foam is depressurized and foamed after being pressurized for 5-8 minutes, for example, 5 minutes, 5.3 minutes, 5.6 minutes, 5.9 minutes, 6.2 minutes, 6.5 minutes, 6.8 minutes, 7.1 minutes, 7.4 minutes, 7.7 minutes or 8 minutes, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0043] The main materials are nitrile rubber, polyurethane, and polyvinyl chloride, wherein the mass ratio of nitrile rubber, polyurethane, and polyvinyl chloride is 3:1:1.

[0044] The accelerator is accelerator CZ and / or accelerator TMTD;

[0045] Secondly, the present invention provides a flexible carbonized flame-retardant thermal insulation material. The mass ratio of the main material, in-situ crosslinking plasticizer, dioctyl phthalate, dynamic crosslinking prepolymer, hydrogen-bonded toughening graft copolymer, silica, stearic acid, zinc oxide, antimony trioxide, AC foaming agent, urea, sulfur, and accelerator in the flexible carbonized flame-retardant thermal insulation material is 100:(10-20):(10-20):(5-10):(5-8):(10-15):(2-3):(3-5):(5-8):(8-12):(0.1-2):(1-1.5):(1-2).

[0046] In this application, polytetrahydrofuran (PTF) reacts with isophorone diisocyanate (IOD). The terminal hydroxyl groups of PTF react with the isocyanate groups of IOD to form urethane bonds, thus forming the initial polyurethane backbone. PTF provides a long-chain flexible structure, imparting good flexibility and elasticity to the material; IOD forms certain hard segments, ensuring mechanical strength.

[0047] Based on this, 2,2ʹ-dithiodiethanol is introduced for the reaction. 2,2ʹ-dithiodiethanol contains two hydroxyl groups, which can react with residual isocyanate groups to form a reversible dynamic cross-linked structure, achieving reversible breakage and recombination of sulfur bonds. This dynamic cross-linking improves the material's plasticity and self-healing ability during processing and use, and also promotes the formation of a dense carbonized layer under high temperatures, reducing the generation of flammable products. The carbonized layer can block further heat and oxygen intrusion under heat sources, thus achieving a dual effect of flame retardancy and heat insulation.

[0048] The prepared dynamic crosslinked prepolymer can stabilize the melt and prevent cell collapse during the subsequent foaming stage. During vulcanization and high-temperature treatment, the dynamic bond recombination and carbonization layer formation endow the material with excellent resilience and resistance to permanent compression deformation. It can also form a heat-insulating carbonized shell in a timely manner under flame or high-temperature environment, playing a role in flame retardancy and thermal protection.

[0049] This application also involves the reaction of polycaprolactone diol with N-(2-aminoethyl)ethanolamine. During the high-temperature reaction, the ester bonds are attacked by the amine groups, generating a graft copolymer of amide bonds and hydroxyl groups. The multiple amide bonds provide a rich hydrogen bond network, which can repeatedly break and reform under external force or high temperature, providing toughness and structural stability to the matrix. The hydrogen bond network not only enhances the bonding at multiphase interfaces and prevents crack propagation, but also works in conjunction with the carbonized layer generated by dynamic crosslinking to further stabilize the material's skeletal structure under high-temperature conditions, reducing thermal decomposition and protecting the internal matrix. Therefore, this hydrogen-bonded toughened graft copolymer not only improves the tear strength of the material, but also promotes the uniform formation of the carbonized layer, enhancing flame retardancy and thermal insulation effects.

[0050] Simultaneously, this application utilizes the reaction of phenol with hexamethylene diisocyanate to prepare phenol-terminated isocyanate, thereby avoiding spontaneous reactions of isocyanate groups during storage or compounding; it then reacts with polyethylene glycol to generate a cross-linked polymer network. This in-situ cross-linking plasticizer is decapsulated during the vulcanization stage, and the released isocyanate groups further cross-link with the residual hydroxyl and amino groups in the system, forming a denser chemical cross-linked network, while also promoting the integrity of carbonization of the material when heated. This plasticizer can improve flow and processing properties and provide flexibility at room temperature, while also providing flame retardancy and heat insulation at high temperatures, avoiding the problems of migration or volatilization of traditional plasticizers.

[0051] During the mixing stage, the dynamically cross-linked prepolymer enhances the stability of the cell structure through the reversible cross-linking of sulfur bonds, preventing the cells from collapsing or merging due to external forces or thermal stress. The hydrogen-bonded toughened graft copolymer inhibits crack propagation by forming a hydrogen bond network, improving the overall mechanical properties and thermal stability of the material. The combined effect of polyvinyl chloride, in-situ cross-linking plasticizer, and dioctyl phthalate gives the material both a certain degree of flexibility and the ability to form a carbonized protective layer under heat; nitrile rubber enhances oil resistance and overall mechanical properties.

[0052] Antimony trioxide exhibits a synergistic flame-retardant effect with chlorine-containing groups and other halogen sources in materials: during combustion, antimony trioxide reacts with halogen compounds or halogen free radicals produced during decomposition to generate antimony halide compounds with stronger flame-retardant properties, inhibiting the combustion chain reaction; simultaneously, at high temperatures, antimony trioxide catalyzes the carbonization process on the material surface, and together with the formed char layer, it provides oxygen and heat insulation. Therefore, antimony trioxide can both synergize with the halogen-containing elements inherent in the material to suppress flames and promote the densification of the char layer during combustion, effectively slowing down the release of heat and combustible gases.

[0053] Furthermore, stearic acid and zinc oxide synergistically form zinc stearate, promoting vulcanization and improving filler dispersibility. Zinc oxide also further enhances the material's heat resistance and anti-aging properties, improving stability during the foaming process. Silica increases the density of the network structure to improve overall mechanical strength, while also playing a stabilizing role in the early formation and template formation of cells. AC foaming agent and urea work together to stabilize the cell gradient and cell size, ensuring the material's lightweight and thermal insulation properties after foaming; further vulcanization and crosslinking are completed with the assistance of sulfur and accelerators. The resulting multiphase crosslinked foam material can rapidly form a carbonized thermal insulation layer under high-temperature conditions, achieving excellent flexible carbonization, flame retardancy, and thermal insulation properties.

[0054] Thirdly, the present invention provides the application of a flexible carbonized flame-retardant thermal insulation material in flame-retardant fabrics.

[0055] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0056] In this application, a preliminary polyurethane backbone containing urethane bonds is formed by reacting polytetrahydrofuran with isophorone diisocyanate. Polytetrahydrofuran provides flexibility and elasticity, while isophorone diisocyanate ensures mechanical strength. Based on this, 2,2ʹ-dithiodiethanol is introduced, reacting with the remaining isocyanate groups to form a reversible dynamic crosslinked structure. This achieves plasticity, self-healing properties, and the formation of a carbonized layer under heat treatment, reducing flammable products and blocking heat and oxygen. The prepared dynamic crosslinked prepolymer prevents cell collapse during subsequent foaming stages and provides excellent resilience, compression resistance, flame retardancy, and thermal protection properties through dynamic bond recombination and the carbonized layer.

[0057] This application utilizes the reaction of polycaprolactone diol with N-(2-aminoethyl)ethanolamine to generate a graft copolymer containing amide bonds and hydroxyl groups, forming a hydrogen bond network that can be repeatedly broken and recombined, thus endowing the material with toughness, structural stability, and tear strength. Simultaneously, the hydrogen bond network and the dynamically cross-linked carbonized layer work synergistically to stabilize the skeletal structure at high temperatures, reduce thermal decomposition, and enhance the material's flame retardancy and thermal insulation properties.

[0058] This application utilizes phenol-terminated isocyanate to prevent spontaneous reaction of isocyanate groups and reacts with polyethylene glycol to form a cross-linked network. This in-situ cross-linking plasticizer is de-encapsulated during the vulcanization stage, further cross-linking to form a dense network, improving carbonization integrity, and combining improved flexibility and processing performance at room temperature with flame retardancy and heat insulation effects at high temperatures, while avoiding the migration or volatilization problems of traditional plasticizers.

[0059] This application utilizes the synergistic effects of dynamic cross-linked prepolymers, hydrogen-bonded toughened graft copolymers, and various additives to stabilize the cell structure and enhance mechanical properties and thermal stability. Antimony trioxide and halogen-containing groups synergistically retard flame, promote densification of the carbonized layer, and inhibit combustion chain reactions. Zinc stearate improves vulcanization and filler dispersibility, while zinc oxide enhances heat resistance and anti-aging properties. Silica enhances network density and stabilizes cell formation. AC foaming agent and urea optimize the cell gradient and lightweight thermal insulation properties. The resulting multiphase cross-linked foam material can rapidly form a dense carbonized layer at high temperatures, exhibiting flexible carbonization, flame retardancy, and thermal insulation properties. Detailed Implementation

[0060] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The embodiments described herein are specific implementations of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be construed as limiting the implementation of the present invention or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application. These technical solutions include technical solutions that employ any obvious substitutions and modifications made to the embodiments described herein.

[0061] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone further purification or processing.

[0062] Nitrile rubber type: NBR2907;

[0063] Polyurethane model: Qilu Petrochemical S-1300;

[0064] Polyvinyl chloride model: Yuyao Huihong MU-2068.

[0065] Example 1

[0066] This embodiment provides a flexible carbonized flame-retardant thermal insulation material and its preparation method. The preparation method of the flexible carbonized flame-retardant thermal insulation material specifically includes the following steps:

[0067] S1: Polytetrahydrofuran 2000 and isophorone diisocyanate were added to tetrahydrofuran at a mass ratio of 1:0.23. Dibutyltin dilaurate was added to obtain reaction solution A, wherein the amount of dibutyltin dilaurate was 0.3% of the total mass of polytetrahydrofuran 2000 and isophorone diisocyanate. The reaction was carried out at 50°C for 1.8 h. 2,2ʹ-dithiodiethanol and 1,4-diazabicyclo[2] were added. 2.2]Octane was used to obtain reaction solution B, wherein the amount of 2,2ʹ-dithiodiethanol was 8% of the total mass of polytetrahydrofuran 2000 and isophorone diisocyanate, and the amount of 1,4-diazabicyclo[2.2.2]octane was 0.45% of the total mass of polytetrahydrofuran 2000 and 2,2ʹ-dithiodiethanol. The reaction was continued at 78°C for 2 hours, and the product was obtained by vacuum distillation and drying to obtain a dynamically crosslinked prepolymer.

[0068] S2: Polycaprolactone diol and N-(2-aminoethyl)ethanolamine were placed in a molten reactor at a mass ratio of 3.5:1. Under a nitrogen atmosphere, the mixture was preheated at 50°C for 40 min and then reacted at 170°C for 5 h to obtain a pretreated product. After cooling, the product was washed, dried, pulverized, and sieved to obtain a hydrogen-bonded toughened graft copolymer.

[0069] S3: Hexamethylene diisocyanate and phenol were melt-mixed at a molar ratio of 1:1.1, and dibutyltin dilaurate was added. The mixture was reacted at 105°C for 6 hours, followed by vacuum distillation and treatment to obtain phenol-terminated isocyanate. This isocyanate was then mixed with polyethylene glycol at a molar ratio of 1:1.15 to obtain reaction solution C, which was reacted at 145°C for 2.5 hours. The mixture was then subjected to vacuum distillation and treatment to obtain an in-situ crosslinking plasticizer.

[0070] S4: Polyvinyl chloride, in-situ crosslinking plasticizer, and dioctyl phthalate are added to a mixer and mixed at the first speed until homogeneous. The mixing temperature of the mixer is 153℃ and the first speed is 60 rpm. Polyurethane and dynamic crosslinking prepolymer are added and mixed evenly. Finally, nitrile rubber, hydrogen bond toughening graft copolymer, silica, stearic acid, zinc oxide, and antimony trioxide are added to obtain a preliminary mixture. After preliminary mixing for 1 min, the mixture is mixed at the second speed of 145 rpm for 8 min to obtain a mitered material. After cooling, it is placed in a two-roll mill. AC foaming agent and urea are added and mixed evenly. Sulfur and accelerator CZ are added and mixed evenly. After mixing, the mixture is cut into slices and placed on a flat vulcanizing machine at 150℃ and pressurized to 8 MPa. After holding the pressure for 5 min, the pressure is released and foaming is performed to obtain a flexible carbonized flame-retardant thermal insulation material. The mass ratio of the main material, in-situ crosslinking plasticizer, dioctyl phthalate, dynamic crosslinking prepolymer, hydrogen-bonded toughening graft copolymer, silica, stearic acid, zinc oxide, antimony trioxide, AC foaming agent, urea, sulfur, and accelerator is 100:18:12:8:7:12:2.5:4:6:11:1.5:1.2:1.8.

[0071] The main materials are nitrile rubber, polyurethane, and polyvinyl chloride, with a mass ratio of nitrile rubber, polyurethane, and polyvinyl chloride of 3:1:1.

[0072] Example 2

[0073] This embodiment provides a flexible carbonized flame-retardant thermal insulation material and its preparation method. The preparation method of the flexible carbonized flame-retardant thermal insulation material specifically includes the following steps:

[0074] S1: Polytetrahydrofuran 2000 and isophorone diisocyanate were added to tetrahydrofuran at a mass ratio of 1:0.22. Dibutyltin dilaurate was added to obtain reaction solution A, wherein the amount of dibutyltin dilaurate added accounted for 0.2% of the total mass of polytetrahydrofuran 2000 and isophorone diisocyanate. The reaction was carried out at 55°C for 1.5 h. 2,2ʹ-dithiodiethanol and 1,4-diazabicyclo[2.2] were added. [2.2.2]octane was used to obtain reaction solution B, wherein the amount of 2,2ʹ-dithiodiethanol was 11% of the total mass of polytetrahydrofuran 2000 and isophorone diisocyanate, and the amount of 1,4-diazabicyclo[2.2.2]octane was 0.4% of the total mass of polytetrahydrofuran 2000 and 2,2ʹ-dithiodiethanol. The reaction was continued at 80°C for 2.5 h, and the product was obtained by vacuum distillation and drying to obtain dynamic crosslinked prepolymer.

[0075] S2: Polycaprolactone diol and N-(2-aminoethyl)ethanolamine were placed in a molten reactor at a mass ratio of 3.8:1. Under a nitrogen atmosphere, the mixture was preheated at 55°C for 30 min and then reacted at 160°C for 5.5 h to obtain a pretreated product. After cooling, the product was washed, dried, pulverized, and sieved to obtain a hydrogen-bonded toughened graft copolymer.

[0076] S3: Hexamethylene diisocyanate and phenol were melt-mixed at a molar ratio of 1:1, and dibutyltin dilaurate was added. The mixture was reacted at 108°C for 7 h, followed by vacuum distillation and treatment to obtain phenol-terminated isocyanate. This isocyanate was then mixed with polyethylene glycol at a molar ratio of 1:1.1 to obtain reaction solution C, which was reacted at 148°C for 2.8 h. The mixture was then subjected to vacuum distillation and treatment to obtain an in-situ crosslinking plasticizer.

[0077] S4: Polyvinyl chloride, in-situ crosslinking plasticizer, and dioctyl phthalate are added to a mixing mill and mixed at the first speed until homogeneous. The mixing temperature of the mixing mill is 154℃ and the first speed is 70 rpm. Polyurethane and dynamic crosslinking prepolymer are added and mixed evenly. Finally, nitrile rubber, hydrogen bond toughening graft copolymer, silica, stearic acid, zinc oxide, and antimony trioxide are added to obtain a preliminary mixture. After preliminary mixing for 1.5 min, the mixture is mixed at the second speed of 148 rpm for 5 min to obtain a mixed material. After cooling, it is placed in a two-roll mill, and AC foaming agent and urea are added and mixed evenly. Then, sulfur and accelerator TMTD are added and mixed evenly. After mixing, the mixture is cut into slices and placed on a flat vulcanizing machine at 155℃ and pressurized to 9 MPa. After holding the pressure for 6 min, the pressure is released and foaming is performed to obtain a flexible carbonized flame-retardant thermal insulation material. The mass ratio of the main material, in-situ crosslinking plasticizer, dioctyl phthalate, dynamic crosslinking prepolymer, hydrogen-bonded toughening graft copolymer, silica, stearic acid, zinc oxide, antimony trioxide, AC foaming agent, urea, sulfur, and accelerator is 100:10:15:5:6:14:2:4.5:5:10:1:1.3:1.

[0078] The main materials are nitrile rubber, polyurethane, and polyvinyl chloride, with a mass ratio of nitrile rubber, polyurethane, and polyvinyl chloride of 3:1:1.

[0079] Example 3

[0080] This embodiment provides a flexible carbonized flame-retardant thermal insulation material and its preparation method. The preparation method of the flexible carbonized flame-retardant thermal insulation material specifically includes the following steps:

[0081] S1: Polytetrahydrofuran 2000 and isophorone diisocyanate were added to tetrahydrofuran at a mass ratio of 1:0.2. Dibutyltin dilaurate was added to obtain reaction solution A, wherein the amount of dibutyltin dilaurate was 0.35% of the total mass of polytetrahydrofuran 2000 and isophorone diisocyanate. The reaction was carried out at 58°C for 1 h. 2,2ʹ-dithiodiethanol and 1,4-diazabicyclo[2.2] were added. 2] Octane was used to obtain reaction solution B, wherein the amount of 2,2ʹ-dithiodiethanol was 12% of the total mass of polytetrahydrofuran 2000 and isophorone diisocyanate, and the amount of 1,4-diazabicyclo[2.2.2]octane was 0.48% of the total mass of polytetrahydrofuran 2000 and 2,2ʹ-dithiodiethanol. The reaction was continued at 70°C for 2.8 h, and the product was obtained by vacuum distillation and drying to obtain dynamic crosslinked prepolymer;

[0082] S2: Polycaprolactone diol and N-(2-aminoethyl)ethanolamine were placed in a molten reactor at a mass ratio of 3:1. Under a nitrogen atmosphere, the mixture was preheated at 60°C for 50 min and then reacted at 175°C for 5.8 h to obtain a pretreated product. After cooling, the product was washed, dried, pulverized, and sieved to obtain a hydrogen-bonded toughened graft copolymer.

[0083] S3: Hexamethylene diisocyanate and phenol were melt-mixed at a molar ratio of 1:1.15, and dibutyltin dilaurate was added. The mixture was reacted at 100°C for 7.5 h, followed by vacuum distillation and treatment to obtain phenol-terminated isocyanate. This isocyanate was then mixed with polyethylene glycol at a molar ratio of 1:1 to obtain reaction solution C. The mixture was reacted at 140°C for 2 h, followed by vacuum distillation and treatment to obtain an in-situ crosslinking plasticizer.

[0084] S4: Polyvinyl chloride, in-situ crosslinking plasticizer, and dioctyl phthalate are added to a mixing mill and mixed at the first speed until homogeneous. The mixing temperature of the mixing mill is 150℃ and the first speed is 75 rpm. Polyurethane and dynamic crosslinking prepolymer are added and mixed evenly. Finally, nitrile rubber, hydrogen-bonded toughening graft copolymer, silica, stearic acid, zinc oxide, and antimony trioxide are added to obtain a preliminary mixture. After preliminary mixing for 1.8 min, the mixture is mixed at the second speed of 140 rpm for 7 min to obtain a mixed material. After cooling, it is placed in a two-roll mill, and AC foaming agent and urea are added and mixed evenly. Then, sulfur, accelerator CZ, and accelerator TMTD are added and mixed evenly. After mixing, the mixture is cut into slices and placed on a flat vulcanizing machine at 157℃ and pressurized to 9.5 MPa. After holding the pressure for 7 min, the pressure is released and foaming is performed to obtain a flexible carbonized flame-retardant thermal insulation material. The mass ratio of the main material, in-situ crosslinking plasticizer, dioctyl phthalate, dynamic crosslinking prepolymer, hydrogen-bonded toughening graft copolymer, silica, stearic acid, zinc oxide, antimony trioxide, AC foaming agent, urea, sulfur, and accelerator is 100:20:10:7:5:10:3:3:7:8:2:1:2.

[0085] The main materials are nitrile rubber, polyurethane, and polyvinyl chloride, with a mass ratio of nitrile rubber, polyurethane, and polyvinyl chloride of 3:1:1.

[0086] Example 4

[0087] This embodiment provides a flexible carbonized flame-retardant thermal insulation material and its preparation method. The preparation method of the flexible carbonized flame-retardant thermal insulation material specifically includes the following steps:

[0088] S1: Polytetrahydrofuran 2000 and isophorone diisocyanate were added to tetrahydrofuran at a mass ratio of 1:0.25. Dibutyltin dilaurate was added to obtain reaction solution A, wherein the amount of dibutyltin dilaurate was 0.4% of the total mass of polytetrahydrofuran 2000 and isophorone diisocyanate. The reaction was carried out at 60°C for 2 hours. 2,2ʹ-dithiodiethanol and 1,4-diazabicyclo[2.2.2]octane were added to obtain reaction solution B, wherein the amount of 2,2ʹ-dithiodiethanol was 10% of the total mass of polytetrahydrofuran 2000 and isophorone diisocyanate, and the amount of 1,4-diazabicyclo[2.2.2]octane was 0.5% of the total mass of polytetrahydrofuran 2000 and 2,2ʹ-dithiodiethanol. The reaction was carried out at 75°C for 3 hours. The product was then distilled under reduced pressure and dried to obtain a dynamically crosslinked prepolymer.

[0089] S2: Polycaprolactone diol and N-(2-aminoethyl)ethanolamine were placed in a molten reactor at a mass ratio of 4:1. Under a nitrogen atmosphere, the mixture was preheated at 58°C for 60 min and then reacted at 180°C for 6 h to obtain a pretreated product. After cooling, the product was washed, dried, pulverized, and sieved to obtain a hydrogen-bonded toughened graft copolymer.

[0090] S3: Hexamethylene diisocyanate and phenol were melt-mixed at a molar ratio of 1:1.2, and dibutyltin dilaurate was added. The mixture was reacted at 110°C for 8 hours, followed by vacuum distillation and treatment to obtain phenol-terminated isocyanate. This isocyanate was then mixed with polyethylene glycol at a molar ratio of 1:1.2 to obtain reaction solution C, which was reacted at 150°C for 3 hours. The mixture was then subjected to vacuum distillation and treatment to obtain an in-situ crosslinking plasticizer.

[0091] S4: Polyvinyl chloride, in-situ crosslinking plasticizer, and dioctyl phthalate are added to a mixer and mixed at the first speed until homogeneous. The mixing temperature of the mixer is 155℃ and the first speed is 80 rpm. Polyurethane and dynamic crosslinking prepolymer are added and mixed evenly. Finally, nitrile rubber, hydrogen bond toughening graft copolymer, silica, stearic acid, zinc oxide, and antimony trioxide are added to obtain a preliminary mixture. After preliminary mixing for 2 minutes, the mixture is mixed at the second speed of 150 rpm for 10 minutes to obtain a mitered material. After cooling, it is placed in a two-roll mill. AC foaming agent and urea are added and mixed evenly. Sulfur and accelerator CZ are added and mixed evenly. After mixing, the mixture is cut into slices and placed on a flat vulcanizing machine at 160℃ and pressurized to 10 MPa. After holding the pressure for 8 minutes, the pressure is released and foaming is performed to obtain a flexible carbonized flame-retardant thermal insulation material. The mass ratio of the main material, in-situ crosslinking plasticizer, dioctyl phthalate, dynamic crosslinking prepolymer, hydrogen-bonded toughening graft copolymer, silica, stearic acid, zinc oxide, antimony trioxide, AC foaming agent, urea, sulfur, and accelerator is 100:15:20:10:8:15:2.8:5:8:12:1.7:1.5:1.4.

[0092] The main materials are nitrile rubber, polyurethane, and polyvinyl chloride, with a mass ratio of nitrile rubber, polyurethane, and polyvinyl chloride of 3:1:1.

[0093] Comparative Example 1

[0094] This comparative example provides a flexible carbonized flame-retardant thermal insulation material. The difference from Example 1 is that in S1, 2,2ʹ-dithiodiethanol and 1,4-diazabicyclo[2.2.2]octane are not added, and only ordinary polyurethane prepolymer is prepared. Other operating steps and process parameters are exactly the same as in Example 1.

[0095] Comparative Example 2

[0096] This comparative example provides a flexible carbonized flame-retardant thermal insulation material. The difference from Example 1 is that S1 and S4 are omitted and dynamic cross-linked prepolymer is not added. Other operating steps and process parameters are exactly the same as in Example 1.

[0097] Comparative Example 3

[0098] This comparative example provides a flexible carbonized flame-retardant thermal insulation material. The difference from Example 1 is that in S4, the traditional plasticizer dioctyl phthalate is used instead of the in-situ crosslinking plasticizer. Other operating steps and process parameters are exactly the same as in Example 1.

[0099] Comparative Example 4

[0100] This comparative example provides a flexible carbonized flame-retardant thermal insulation material. The difference from Example 1 is that S2 and S4 are omitted and no hydrogen-bonded toughening graft copolymer is added. Other operating steps and process parameters are exactly the same as in Example 1.

[0101] The performance of the flexible carbonized flame-retardant thermal insulation materials of Examples 1-4 and Comparative Examples 1-4 was tested, and the specific process is as follows:

[0102] The thermal conductivity and thermal resistance of the sample were tested according to GB / T 10294-2008, where the sample thickness was 20 mm.

[0103] The tensile strength of the samples was tested according to GB / T 528-2009;

[0104] The flame retardant properties of the samples were tested according to GB / T 2408-2021;

[0105] The test results are shown in Table 1.

[0106] Table 1. Performance test results of flexible carbonized flame-retardant thermal insulation materials in Examples 1-4 and Comparative Examples 1-4

[0107] Thermal conductivity coefficient / (W / (m k)) thermal resistance / ((m 2 • k) / W) Tensile strength (MPa) Vertical burn test Example 1 0.023 0.87 3.2 V-0 Example 2 0.025 0.84 3.0 V-0 Example 3 0.024 0.85 3.1 V-0 Example 4 0.026 0.83 2.9 V-0 Comparative Example 1 0.031 0.67 2.6 V-1 Comparative Example 2 0.033 0.64 1.6 V-2 Comparative Example 3 0.028 0.74 1.4 Severe dripping Comparative Example 4 0.030 0.68 2.9 V-1

[0108] The test results of Example 1 and Comparative Example 1 show that the introduction of 2,2ʹ-dithiodiethanol and 1,4-diazabicyclo[2.2.2]octane can form a reversible dynamic sulfur bond cross-linking structure, which promotes the formation of a dense carbonized layer at high temperatures and reduces heat transfer and diffusion. Without adding 2,2ʹ-dithiodiethanol and 1,4-diazabicyclo[2.2.2]octane, when preparing ordinary polyurethane prepolymers, the reversible recombination of sulfur bonds cannot be achieved due to the lack of a dynamic crosslinking network, resulting in decreased thermal stability and weakened carbonization ability, which in turn increases the thermal conductivity. Ordinary polyurethane prepolymers lack the support of a dynamic crosslinking structure, and the cell distribution may be uneven or collapse, thereby increasing the heat transfer path and reducing the thermal insulation performance. Due to the low crosslinking density of ordinary polyurethane prepolymers, heat is more easily transferred inside the material, resulting in deteriorated thermal insulation performance. Without a dynamic crosslinking network, stress transfer and synergistic effects cannot be formed between the phases, resulting in decreased tensile strength. Dynamic crosslinking promotes the formation of a dense carbonized layer at high temperatures, but without a dynamic crosslinking network, its flame retardant rating decreases.

[0109] The test results from Example 1 and Comparative Example 2 show that the dynamic crosslinking prepolymer is an important modifying component in the material. Its dynamic sulfur bond structure not only improves the mechanical properties of the material but also forms a dense carbonized layer at high temperatures, preventing further intrusion of heat and oxygen. Without the dynamic crosslinking prepolymer, the ability to form a carbonized layer decreases significantly, the thermal resistance of the material decreases, and the insulation effect weakens. During the foaming process, the dynamic crosslinking prepolymer stabilizes the cell structure through the dynamic recombination of sulfur bonds. If this component is lacking, the cells are prone to collapse or merge during mixing and vulcanization, resulting in uneven cell distribution and increased thermal conductivity. The dynamic crosslinking prepolymer promotes the integrity and density of the carbonized layer at high temperatures through sulfur bond recombination. Omitting this component reduces the material's high-temperature resistance and flame retardancy, leading to deterioration of thermal conductivity. Without the dynamic crosslinking prepolymer, the system cannot provide a long-chain flexible structure and a basic crosslinking network, resulting in decreased tensile strength. Without the prepolymer, fewer carbon layers are formed during combustion, which cannot effectively block heat and oxygen, thus reducing the flame retardancy rating.

[0110] Based on the test results of Example 1 and Comparative Example 3, in S4, the traditional plasticizer dioctyl phthalate was used instead of the in-situ crosslinking plasticizer. Dioctyl phthalate is a physical plasticizer, which is prone to migration or volatilization. Especially under high temperature conditions, its thermal stability is poor, and it cannot effectively participate in the crosslinking of the system, resulting in a decrease in the thermal insulation and flame retardancy of the material. The in-situ crosslinking plasticizer can improve the flowability and cell uniformity of the material during the processing stage, while the volatility of the traditional plasticizer may lead to uneven cell wall thickness and increase the heat conduction path. The migration of dioctyl phthalate will lead to a decrease in the long-term thermal resistance of the material, especially under high temperature aging conditions, the thermal conductivity will further increase. The traditional plasticizer cannot effectively participate in crosslinking, resulting in a decrease in tensile strength. Moreover, the traditional plasticizer acts as an additional fuel during combustion, which will aggravate the degree of combustion and cause severe melt dripping.

[0111] The test results from Example 1 and Comparative Example 4 show that the hydrogen-bonded toughening graft copolymer constructs a multi-layered hydrogen bond network through its abundant amide bonds and hydroxyl groups. These hydrogen bond networks can repeatedly break and reform at high temperatures, enhancing the mechanical and thermal resistance properties of the material. Omitting this component reduces the microstructural stability of the material, making cracks easier to propagate, decreasing cell wall strength, and increasing the heat conduction path. The hydrogen-bonded toughening graft copolymer synergistically works with the dynamically cross-linked structure at high temperatures, promoting the uniformity and density of the carbonized layer. Removing this component reduces the structural integrity of the carbonized layer and weakens its ability to block heat transfer. The hydrogen-bonded toughening graft copolymer improves the material's compressive strength and resilience, preventing deformation of the cell structure during processing and use. Removing this component may cause irreversible deformation of the cells, further reducing thermal resistance. The carbon layer formed after omitting this component is less uniform and more fragile, thus reducing the protective efficiency of the carbon layer and lowering its flame retardant rating. The impact on tensile strength is relatively small.

[0112] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a flexible carbonized flame-retardant thermal insulation material, characterized in that, The preparation method includes: S1: Polytetrahydrofuran 2000 and isophorone diisocyanate were added to tetrahydrofuran to obtain reaction solution A. After the reaction, 2,2ʹ-dithiodiethanol and 1,4-diazabicyclo[2.2.2]octane were added to obtain reaction solution B. The reaction was continued and post-treated to obtain dynamic crosslinked prepolymer. S2: Polycaprolactone diol and N-(2-aminoethyl)ethanolamine are placed in a molten reaction vessel and reacted under a nitrogen atmosphere to obtain a pretreated product, which is then post-treated to obtain a hydrogen-bonded toughened graft copolymer. S3: Hexamethylene diisocyanate and phenol are melt-mixed and reacted to obtain phenol-terminated isocyanate; it is then mixed with polyethylene glycol to obtain reaction solution C, reacted, and post-treated to obtain an in-situ crosslinking plasticizer. S4: Polyvinyl chloride, in-situ crosslinking plasticizer, and dioctyl phthalate are added to a mixer and mixed until homogeneous. Polyurethane and dynamic crosslinking prepolymer are added and mixed until homogeneous. Finally, nitrile rubber, hydrogen-bonded toughening graft copolymer, silica, stearic acid, zinc oxide, and antimony trioxide are added to obtain a preliminary mixture. After preliminary mixing, the mixture is mixed at a second speed to obtain a mitered compound. After cooling, it is placed in an open mill, and AC foaming agent and urea are added and mixed. Sulfur and accelerator are added and mixed until homogeneous. The mixture is then slit to obtain mixed slices, which are placed on a flat vulcanizing machine and pressed. After depressurization and foaming, flexible carbonized flame-retardant thermal insulation material is obtained.

2. The method for preparing a flexible carbonized flame-retardant thermal insulation material according to claim 1, characterized in that, In S1: the mass ratio of polytetrahydrofuran 2000 to isophorone diisocyanate is 1:(0.2-0.25).

3. The method for preparing a flexible carbonized flame-retardant thermal insulation material according to claim 1, characterized in that, In S1: The amount of 2,2ʹ-dithiodiethanol added accounts for 8-12% of the total mass of polytetrahydrofuran 2000 and isophorone diisocyanate; The amount of 1,4-diazabicyclo[2.2.2]octane fed is 0.4-0.5% of the total mass of polytetrahydrofuran 2000 and 2,2ʹ-dithiodiethanol.

4. The method for preparing a flexible carbonized flame-retardant thermal insulation material according to claim 1, characterized in that, In S2: the mass ratio of the polycaprolactone diol to N-(2-aminoethyl)ethanolamine is (3-4):

1.

5. The method for preparing a flexible carbonized flame-retardant thermal insulation material according to claim 1, characterized in that, In S3: The molar ratio of the hexamethylene diisocyanate to phenol in the melt mixture is 1:(1-1.2). The molar ratio of the phenol-terminated isocyanate to polyethylene glycol is 1:(1-1.2).

6. The method for preparing a flexible carbonized flame-retardant thermal insulation material according to claim 1, characterized in that, In S4: The mixing temperature in the internal mixer is 150-155℃; The first rotational speed of the internal mixer for mixing is 60-80 rpm; The second rotation speed of the internal mixer for mixing is 140-150 rpm.

7. The method for preparing a flexible carbonized flame-retardant thermal insulation material according to claim 1, characterized in that, In S4: The main materials are nitrile rubber, polyurethane, and polyvinyl chloride, wherein the mass ratio of nitrile rubber, polyurethane, and polyvinyl chloride is 3:1:

1. The accelerator is accelerator CZ and / or accelerator TMTD.

8. The method for preparing a flexible carbonized flame-retardant thermal insulation material according to claim 7, characterized in that, In S4: the mass ratio of the main material, in-situ crosslinking plasticizer, dioctyl phthalate, dynamic crosslinking prepolymer, hydrogen bond toughening graft copolymer, silica, stearic acid, zinc oxide, antimony trioxide, AC foaming agent, urea, sulfur, and accelerator is 100:(10-20):(10-20):(5-10):(5-8):(10-15):(2-3):(3-5):(5-8):(8-12):(01-2):(1-1.5):(1-2).

9. A flexible carbonized flame-retardant thermal insulation material, characterized in that, It is prepared according to any one of claims 1-8.

10. The application of a flexible carbonized flame-retardant thermal insulation material prepared by the preparation method according to any one of claims 1-8 in flame-retardant fabrics.